Econstudentlog

The Incas and their Ancestors: The archaeology of Peru (1)

Here’s the link, the average goodreads rating is 3.55. I found the book via the AskAnthropology reading list.

It’s not the first book I read on this specific subject (THP also covers some of this stuff, but in much less detail), however we know a lot more now than we did when Métraux wrote his book (as Moseley puts it in the introduction, “Due to a tremendous escalation in Andean studies, more archaeological, historical, and anthropological research has been carried out during the current generation than during all prior centuries.”) so I’m learning a lot. A really nice thing about the book is that although it deals only with a very specific group of people, it still has some focus on highlighting general principles regarding human development. Of course a book like Boyd and Richerson’s The Origin and Evolution of Cultures (I’m planning on reading this at some point..) presumbly deals with such matters in much more detail, but it’s still nice to have at least some big-picture stuff in a book like this.

Some stuff from the first half or so of the book, as well as a few comments:

“Just as the historical accounts of Tahuantinsuyu are not without prejudice, the archaeological record did not remain unbiased by the Spanish arrival. The conquering forces quickly learned that great stores of precious metal existed in the ground. Much was purely geological in context, but the tombs of past lords and nobles also contained enormous stores of gold and silver. Within a generation of the conquest, looting operations grew so large and financially rewarding that they became legally synonymous with mining. Ancient monuments were divided into claim areas with titles registered in notarial archives. Title holders established chartered corporations to mobilize massive work forces and systematically quarry ruins. As with geological mines, the Castilian king was entitled to a 20 percent tax on all wealth extracted from the ground. Within a short span the Crown established a royal smelter in the Moche valley, not because of any local geological wealth but because the royal mausoleums of Chan Chan had been discovered and looting of the nearby Pyramid of the Sun was underway. […] the Andean Cordillera is probably the most intensively looted ancient center of civilization in the world.”

“Thanks to the rugged Cordillera, which is characterized by global extremes in environmental conditions, Andean civilization differs from other great civilizations of antiquity. If thriving civilizations had matured atop the Himalayas while simultaneously accomodating a Sahara desert, a coastal fishery richer than the Bering Sea, and a jungle larger than the Congo, then Tahuantinsuyu might seem less alien. Fundamental contrasts in the Andean Cordillera’s habitats confronted humans with radically disparate conditions and dissimilar ressources. […] The mountain, marine, desert and jungle habitats required distinctive adaptive strategies and promoted different evolutionary pathways, called Arid Montane, Maritime-Oasis, and Tropical Forest lifeways. The Incas were a montane society, but the land of the four quarters incorporated people adapted to other conditions.” (Many large civilizations of the past have had huge environmental variation within their borders, so I think Moseley may be overemphasizing here how unique the Inca empire was in this regard (see e.g. here), but it seems beyond argument that environmental factors played a major role in the structure and development of the Inca state.)

“About 90 percent of Andean runoff descends to the Atlantic watershed, while only 10 percent descends to the Pacific.”

“cold and anoxia oblige people to eat more, and highlanders are estimated to need around 11.5 percent more calories than lowlanders. Consequently, it costs measurably more to support life and civilization in mountains than in lowlands. Life is also more precarious because comparable food shortages, caused by drought and other disasters, exert greater nutritional duress at higher elevations than at lower ones. […] [But on the other hand…] High-altitude rainfall farming fluctuates less severely than low-elevation runoff farming and irrigation. Arid mountain soils, like sponges, absorb fixed amounts of moisture and must reach saturation before rainfall will produce runoff. […] if rainfall fluctuates by 10 percent […] then runoff [may] fluctuate on the order of 36 percent. […] the flow of Andean rivers fluctuates dramatically from year to year. […] Normally, runoff farming generates much higher yields than rainfall farming. […] During drought, rainfall farming is depressed less severely than runoff farming and coastal irrigation suffers the most because it is furthest away from mountain precipitation.”

“Seasonal variation increases with elevation, and plant-growth cycles are successively shorter at progressively higher altitudes. In the towering mountains, ecological zones are compressed and stacked atop one another. Andean people can trek 100 km as the crow flies and go from hilly jungle to alpine tundra, crossing counterparts of the major continental life zones. Mountain populations around the world pursue farming, herding, and the exploitation of multiple ecological zones because stacked habitats with different growing seasons are close together and the productivity of different zones fluctuates from year to year. In the Andes, this exploitation pattern moves people and produce up and down the mountains, and it is called ‘verticality’ in contrast to ‘horizontality’ which typifies lowland movement.
Verticality and horizontality are associated with different means of procuring resources. Mountain families typically exploit three or more ecological zones […] Consequently, they directly procure commodities from a series of habitats by moving produce along a vertical or elevational axis […] Alternatively, in desert and tropical lowlands people generally make their living in a single continental life zone. Because major zones are far apart, resources from distant habitats are procured indirectly by trade, barter, or exchange with other people […] In the world’s highest mountains many forces of natural selection are similar, including anoxia, cold temperatures, frost, hail, poor soils, short growing seasons, very limited crop diversity [few crops can survive in very high altitudes – US], rugged topography, and marked fainfall variation over short distances. Consequently, human populations in the Alps, Himalayas, and Andes exhibit many parallel adaptions, including symbiotic integration of agricultural and pastoral production, exploitation of multiple ecological zones, reliance on different crops from different altitudes, sequential timing of work in different ecological tiers, dependence upon dung fertilizer, frequent fallowing of fields, emphasis on long-term storage of food products, relatively little sexual division of labor in subsistence tasks, and a mixture of household and communal control of land use.”

“Mountain political centers, such as Cuzco, Huari, and Tiwanaku, expanded both through the uplands as well as down into the lowlands where resource diversity was greatest. In contrast, coastal centers, such as Chimor and Moche, expanded along the Pacific littoral, with little penetration into the highlands above 2000 m”

“Labor was the coin of the realm and the imperial economy extracted tribute in the form of work. […] [There were] three types of labor for the state that can be called agricultural taxation, mit’a service, and textile taxation. […] Agricultural taxation extracted work from both men and women. Commoners did not own land – it belonged to the ayllu. It was Inca practice to divide conquered agricultural land into three categories, ideally of equal size, all of which the peasantry was obliged to farm. The first category was dedicated to the support of the gods […] These lands were cultivated first, before other categories of fields. Yields went to support religious functionaries, priests, and shrine attendants […] The second category of fields belonged to the emperor […] Imperial fields were tended after religious ones, and yields went to support the imperial court and the needs of government. […] agrarian tribute from both religious and imperial lands was largely under Cuzco’s direct control. […] The third category of land was assigned to the local community for its support, redistributed annually to village members by the local kuraka. This allotment was not in equal parts, but proportional to the size of a family and the number of dependents under each head-of-household. As households grew or shrank, their share of land changed. […] Puna pasture lands and llama and alpaca resources were organized in a similar three-fold manner.”

August 31, 2013 Posted by | anthropology, archaeology, books | Leave a comment

David Hume: Essays on Suicide and the Immortality of the Soul

Here’s a link to the text, here’s a goodreads link. I read Hume’s essays and parts of the responses. The responses make it more clear which kinds of competing mental frameworks people applied back then and so they are of historical interest; but I didn’t have to read a lot of that stuff to figure out that the competing mental frameworks were quite stupid and so were not worth my time reading in full. The quotes below are from Hume’s essays:

“A man who retires from life does no harm to society: He only ceases to do good; which, if it is an injury, is of the lowest kind. — All our obligations to do good to society seem to imply something reciprocal. I receive the benefits of society, and therefore ought to promote its interests; but when I withdraw myself altogether from society, can I be bound any longer? But allowing that our obligations to do good were perpetual, they have certainly some bounds; I am not obliged to do a small good to society at the expence of a {19} great harm to myself; why then should I prolong a miserable existence, because of some frivolous advantage which the public may perhaps receive from me? If upon account of age and infirmities, I may lawfully resign any office, and employ my time altogether in fencing against these calamities, and alleviating, as much as possible, the miseries of my future life: why may I not cut short these miseries at once by an action which is no more prejudicial to society? — But suppose that it is no longer in my power to promote the interest of society, suppose that I am a burden to it, suppose that my life hinders some person from being much more useful to society. In such cases, my resignation of life must not only be innocent, but laudable.”

“That Suicide may often be consistent with interest and with our duty to ourselves, no one can question, who allows that age, {21} sickness, or misfortune, may render life a burthen, and make it worse even than annihilation. I believe that no man ever threw away life, while it was worth keeping. For such is our natural horror of death, that small motives will never be able to reconcile us to it; and though perhaps the situation of a man’s health or fortune did not seem to require this remedy, we may at least be assured that any one who, without apparent reason, has had recourse to it, was curst with such an incurable depravity or gloominess of temper as must poison all enjoyment, and render him equally miserable as if he had been loaded with the most grievous misfortunes.”

In related matters I recently watched this lecture and the first half of this. I wouldn’t really recommend them and I didn’t embed them here because I don’t think those lectures are very good; he uses a lot of words to say very little.

August 29, 2013 Posted by | books, Lectures, philosophy | 23 Comments

A couple more Christie novels..

I’ve read Evil Under the Sun and One, Two, Buckle My Shoe. I gave both books four stars. They were enjoyable reads, but in both cases I was closer to three stars than five; some of the previous Christie novels I’ve read I consider to be better written. Evil Under the Sun takes a while to get going, but I’m not sure how to evaluate that book on account of probably having read the first part too fast; it seems reading George Martin recently established a habit of ‘just reading along’ without thinking too much about where you’re going, a habit which took a bit of time to become aware of/get rid of. I only realized that I was reading rather fast after I’d half finished the book, after reading roughly 70 pages/hour during the first couple of hours – that’s not a good way to read a Christie novel, at least I don’t think it is. Not helping was the fact that I believe I’ve read the story before (spoilers hidden in rot-13 below):

V fbzrubj erzrzorerq, gubhtu V jnfa’g pbzcyrgryl fher guvf jnf pbeerpg fb vg jnf cnegyl whfg n ulcbgurfvf, gung gur obql sbhaq ba gur ornpu jnf abg gur obql bs Neyran Znefunyy ohg engure gung bs na nppbzcyvpr jub unq snxrq orvat qrnq sbe gur checbfr bs pbashfvat znggref. Vapvqragnyyl gung fghag gb zr jnf obgu fghcvq naq uvtu evfx; vg pbhyq fb rnfvyl unir onpxsverq – jung vs gur Oerjfgre ynql unq ernpgrq qvssreragyl, unq eha hc gb gur obql gb unir n pybfre ybbx? Ng gur irel yrnfg gur nppbzcyvpr jbhyq unq unq n ybg bs rkcynvavat gb qb. Cerfhznoyl gur vzcynhfvovyvgl nffbpvngrq jvgu fhpprffshyyl chyyvat guvf cneg bs gur pevzr bss jnf cneg bs jul V erzrzorerq guvf fcrpvsvp nfcrpg bs gur fgbel, ohg abg bgure cnegf – V qba’g yvxr vg jura jung V pbafvqre gb or vzcynhfvoyr fgengrtvrf juvpu va n erny-jbeyq frggvat jbhyq or uvtuyl hayvxryl gb jbex ner chyyrq bss jvgu rnfr va obbxf yvxr gurfr. V qvqa’g erzrzore nal bgure fcrpvsvpf ncneg sebz guvf nfcrpg bs gur pevzr gubhtu – V pregnvayl qvqa’g erzrzore jub gur nppbzcyvpr jnf, jung jnf gur zbgvir rgp. – naq V jnf nyjnlf cnegyl va qbhog nobhg jurgure V jnf erzrzorevat pbeerpgyl, fb univat (ernq? jngpurq? Vg znl unir orra n zbivr nqncgvba..) qvq abg ernyyl fcbvy nalguvat.

One, Two, Buckle My Shoe I have never read before, and I deliberately slowed myself down a bit when I started reading it so as not to repeat my mistake. I liked it better than Evil Under the Sun, but it’s not in my opinion quite ‘up there’ with the greatest of her books.

August 28, 2013 Posted by | books | Leave a comment

Handbook of critical care (II)

I finished the book. It was hard to rate, in part because I as mentioned in the first post am not exactly part of the main target audience. However I think the book is reasonably well written and it’s certainly not the authors’ fault that I couldn’t always figure out exactly what was going on because I’m an ignorant fool (compared to most people who’ll read this). I ended up giving it four stars.

I covered the first chapters in my first post about the book, but I’ll not cover the rest of the book in as much detail as I did the first part. Topics covered in the remaining chapters were acute renal failure, neurological emergencies, the endocrine system, gastrointestinal disorders, infection and inflammation, hematologic emergencies, nutritional support, physical injury (including things like burns and electrical injuries, as well as near-drowning, hypothermia and heat stroke – which is incidentally quite a bit more dangerous than I’d imagined), toxicology, a chapter on scoring systems used to assess severity of illness among patients in the ICU, and lastly a brief chapter about obstetric emergencies (pre-/eclampsia and HELLP-syndrome). So a lot of ground is covered here, meaning of course also that they do not go into as much detail in many of these chapters as they did in some of the first ones from which I quoted earlier.

I think reading a book like this may cause your viewing experience associated with watching medical dramas to change at least marginally. Some stuff from the remaining part of the book, as well as some comments:

“Traumatic brain injury
Primary brain injury occurs on impact and is considered irreversible. Secondary brain injury […] results from processes initiated by primary insult that occur some time later and may be prevented or ameliorated. Management of traumatic brain injury (TBI) aims to prevent secondary brain injury.”

“Management of organ donors
Once a potential organ donor has been identified, the regional transplant coordinator should be contacted, but he or she should not be involved in the process of diagnosing brain death or obtaining consent for organ donation. In general, the following features exclude eligibility for organ donation: malignancy (except for primary cerebral, skin, or lip), HIV, hepatitis, intravenous drug abuse, active tuberculosis, and sepsis. However, the regional transplant coordinator should make the determination of eligibility. Once brain death has been declared and the family has consented to organ donation, an aggressive approach to preservation of organ function is crucial.”

“Management of hyponatremia
Correction must not exceed 20 mol/L per 48 h and generally at a rate of no more than 0.5 mmol/L per h.” I was curious to know why, so I looked it up – it turns out that really bad things can happen if adjustment is too fast – this may lead to CPM (central pontine myelinolysis). It’s a recurring theme in the book that adjustment speeds matter, and that optimal treatment does not always imply fast adjustment; to give but one other example this is also the case when it comes to treatment of DKA (“The initial aim is to inhibit ketogenesis, which is achieved with modest doses of insulin. Rapid reductions in blood glucose should be avoided”).

“Within 24 h of admission the majority of critically ill patients will develop stress-related mucosal damage. Clinically relevant bleeding causes hematemesis and/or melena; hypotension, tachycardia, or anemia occurs in 1–4% of patients. Those who develop stress-related mucosal disease, endoscopic signs of bleeding, or clinically important bleeding have a higher risk of death. […] Maintenance of an elevated intragastic pH has the potential to prevent stress-related mucosal disease. Studies have demonstrated that a pH of more than 4.0 is adequate to prevent stress ulceration. However, a pH greater than 6.0 may be necessary to maintain clotting in patients at risk from rebleeding in peptic ulcer disease. […] There are, however, concerns that the elevation in pH in patients may lead to increased episodes of pneumonia.”

“Hypergastrinemia from a gastrinoma tumor causes Zollinger–Ellison syndrome (ZES) leading to gastric acid hypersecretion. Gastrin leads to hypertrophy and hyperplasia of the parietal cells which, in turn, also results in gastric acid hypersecretion. Although a rare disease, it is life threatening. […] ZES can be cured in 30% of patients by surgical resection. More than 50% of patients with control of acid hypersecretion who are not cured will die of tumor-related causes. Surgical resection should, therefore, be pursued whenever possible.” (‘More than 50% of patients with control of acid hypersecretion who are not cured will die of tumor-related causes’ – I’m starting to like my diabetes…)

In chapter 8 it’s noted that 50% of acute liver failure cases in the UK are caused by acetaminophen overdose, and that the various forms of viral hepatitis are behind another 40% of cases.

“Severe infection is not only a common cause of admission to intensive care, but also the most common complication suffered by critically ill patients. […] Hospital-acquired pneumonia (HAP) is defined as a pneumonia diagnosed 48 h or more after admission, which was not incubating at the time of admission. In contrast to the hospital population as a whole (in whom urinary tract and wound infections are more frequent), it is the most common infection in the critically ill, and is associated with a mortality rate of up to 50%.”

No, these are not all caused by the poor hand hygiene of nurses and doctors; 10 specific risk factors are listed and it’s made clear that:

“Although community-acquired pathogens can cause HAP, there is a much higher incidence of infection caused by aerobic Gram-negative bacilli. This is possibly the result of overgrowth of the stomach with intestinal bacteria, or the direct vascular spread of organisms that have translocated across the intestinal wall into the circulation.” On a related note, “There is no clear evidence that duration of residence in itself increases the risk of [nosocomial] bacteremia.” The chapter has some great (and/but brief) descriptions of various antibiotics, antivirals and antifungal medications. Some of the descriptions make it very obvious why such drugs are not always as great as they tend to be made out to be – here’s a presumably well-known example:

“Vancomycin inhibits cell wall synthesis. It is the drug of choice in the treatment of MRSA and coagulase-negative staphylococci that are resistant to meticillin.” Sounds great. But here’s the next sentence: “However, it is nephrotoxic and ototoxic, and serum levels must be monitored carefully.” (To those who don’t speak medical textbook, vancomycin may cause kidney failure and cause you to go deaf.)

“Respiratory function is often compromised in patients with cervical cord injury […] The level of injury critically influences the effect on ventilation […] Patients with lesions above C5 (unable to move hands or arms) usually require ventilation. Patients with intact C5 innervation (can shrug shoulders and externally rotate arms) may maintain adequate respiratory function in the absence of any other pulmonary insult. Patients with lesions at C6 will usually manage without ventilatory support in the acute phase.” Spinal cord damage can cause a lot of ugly stuff to happen besides ‘just’ being unable to move limbs – there may also be systemic problems such as various gastrointestinal problems, bladder distension and urinary retention, and loss of ability to regulate normal body temperature (Poikilothermia) as well as other metabolic problems.

“Supportive care is the basis of all treatment in poisoned patients. A medical history and physical examination can help direct which toxins or poisons are involved. It is important to seek out all sources of information because obtaining a history from an attempted suicide patient may be difficult. There may be deliberate misinformation in this setting. One must always assess for coingestions, as most patients who attempt suicide will use two or more toxins. […] Specific poison assays are often unhelpful as absorption is variable and a poor guide to prognosis. […] There are a limited number of poisons that have specific antidotes […] Many antidotes are toxic in their own right and should be reserved for life-threatening poisonings.”

August 26, 2013 Posted by | books, health care, medicine | Leave a comment

Handbook of critical care (1)

Here’s a link. From the description:

“Written as a teaching aid for residents and fellows in intensive care and emergency medicine, this revised edition of the Handbook of Critical Care is also a valuable reference for all medical professionals in the critical care team. The 15 chapters in this pocket-sized basic intensive care manual include eight substantial sections covering the major organ systems, as well as infection, nutrition, physical injury and toxicology, and brief chapters on scoring systems and obstetrics. The chapters feature numerous pictures, comparative tables, diagrams and lists, and provide essential information for juniors training in intensive care medicine. The definitions, etiology, clinical features and differential diagnoses are well covered, while extensive use of bullet points and numbering increases the clarity of presentation enabling readers to quickly get to the key learning points.”

I’m not a medical professional who’s part of a critical care team (surprise!) and so I don’t understand everything that’s going on in this book, but I still feel like I’m learning quite a bit. I think it’s an interesting book, but I certainly wouldn’t recommend it to someone who’s not spent more time than most obtaining an understanding of the human body, pathophysiology, some pharmacology, etc. – if you’re new to the field of medicine I think you’ll simply get blown away here and you’ll have little clue what’s going on most of the time. Khan Academy has a lot of stuff about the heart, and I’ve watched a lot of the videos dealing with this kind of stuff, though far from all of them – but a couple of textbooks plus learning all the material covered in the lectures I link to above is probably the bare minimum you need in order to understand everything that’s going on in chapter 3 alone. So, yeah…

As pointed out, even though I don’t understand everything doesn’t mean I don’t learn a lot by reading this stuff – that’s not how it works. So so far I’m enjoying this – if I could have been bothered to look up all the new terms I’ve come across here so far, I’d have learned more than I did, but that would have been too much work. I did rewatch a few Khan Academy videos to brush up on some of the concepts, but that’s pretty much all I’ve done, aside from an occasional visit to wikipedia. So I’ve read and understood some of it, and I’ve read and not fully understood other parts. That’s okay.

One thing that I’ve achieved a greater understanding of is how stuff like adverse drug reactionsnosocomial infections etc. may be much harder to avoid and deal with than I’ve tended to believe in the past. All drugs have side effects, and as a general rule I don’t think it’d be wrong to say that the more sick you are, the more extensive health interventions are required to make you better (or simply stop you from getting worse). A patient in the ICU who develops pneumonia as a (more or less direct) consequence of having been on a mechanical ventilator for an extended period of time and dies from it would most likely have died even sooner if he had not been put on a ventilator – he was so sick in the first place that he couldn’t even satisfy his own body’s oxygen demands through breathing… Many treatment options critically ill patients have to choose from (or their medical proxy has to choose from) are quite risky, but it should be kept in mind that the risks associated with not treating the conditions in question are usually much worse. Adding to all of this is the fact that quite a few diseases progress much too fast for treatment to follow diagnosis chronologically; in such cases you need to engage in treatment before you’re even certain what’s wrong. Some drugs will work one way when dosed in a specific manner, but will have more or less the opposite effect if given in a higher dose; now add interpersonal differences in drug metabolism, absorption rates, measurement problems, etc. to the mix… This is not to say that attempts to minimize errors and treatment-associated complications should not be undertaken, far from it, but I think I understand a little better at this point why these problems may sometimes be very hard to address satisfactorily, and why some of these problems are probably even best perceived of as inherent risks which simply cannot be avoided.

I decided to add a few quotes below from the first four chapters (95 pages) of the book. I’ve only added quotes from the stuff I understand. I added some wikipedia links along the way in order to make the stuff a little easier to read.

“Several types of sedative available are commonly used in the ICU […] Drug regimens should of course be matched to the particular needs of individual patients; however, generally speaking, no single drug is ideal and what follows is a summary of the advantages and disadvantages of each drug. […] All sedatives can accumulate in critically ill patients, leading to a prolonged sedative effect. This may increase the duration of mechanical ventilation, length of stay in the ICU, and length of stay in the hospital, and lead to complications such as ventilator-associated pneumonia. A strategy to reduce drug accumulation should be implemented […]

“studies that have failed to demonstrate an improved outcome in critical patients have cast doubt on the clinical value of PACs. [PAC: Pulmonary Artery Catheter, US] Nevertheless, traditional indications include the following: [Long list omitted here] […] To date, the use of PAC monitoring has not been shown to confer a clinical benefit in any of these settings.”

“A wide range of inotropes and vasopressors is available to help support CO [cardiac output] or blood pressure (BP). […] Inotropes that vasodilate and vasoconstrict are known as inodilators and inoconstrictors, respectively. Vasoconstrictors should always increase blood pressure, but may have a variable effect on CO. Many of these drugs have the potential to cause myocardial ischemia due to increases in cardiac workload, tachycarrhythmias, etc, and thus as electrocardiogram (EKG) and (preferably direct) arterial pressure monitoring are mandatory during their use. Vasoconstrictor drugs must be given into a central vein.”

“Hypertension is not uncommon in critically ill patients and may worsen myocardial ischemia and increase oxygen requirements. […] Injudicious use of hypotensive drugs reduces perfusion pressure (eg, kidney, brain, myocardium) and may lead to organ dysfunction.”

Heart failure occurs when the heart fails to maintain a CO sufficient for the metabolic needs of the body, or when it can only do so at the expense of abnormally elevated end-diastolic pressures. Heart failure is not a diagnosis as such, but a clinical syndrome; consequently the underlying disease must always be sought and treated.
Chronic heart failure has increased in incidence due to a decline in mortality from acute myocardial infarction, and an increase in the elderly population. It carries a significant mortality risk, with a 5-year survival rate of approximately 30%.
Acute cardiac failure is a medical emergency with a high mortality rate […] in which diagnosis of the cause and empirical treatment may have to be carried out simultaneously.”

“Pathogenesis of AMI
Rupture of an atheromatous plaque within the lumen of a coronary artery, and the subsequent formation of fresh thrombus, leads to vascular occlusion and (total) cessation of blood flow to the region of the myocardium supplied by that artery. Hypotension, hypoxemia, and local vasospasm may extend the size of the resulting infarct by compromising the blood supply of surrounding ischemic muscle. […] There is ischemic pain, typically retrosternal, spreading across the chest, and possibly radiating to the arms, throat, jaw, and back. The pain lasts for more than 20 min and may be atypical (eg, epigastric) which may confuse the diagnosis. A silent (ie, painless) infarction is more common in elderly people and those with diabetes. […] Less than 10% of patients with enzyme-proven infarcts will have two normal EKGs performed 30 min apart in the hyperacute phase. This establishes electrocardiography as an important initial investigation in the patient with a history suggestive of AMI. […] Aspirin combined with streptokinase improves the reduction in mortality rate from 25% to 42% by preventing reocclusion of thrombolyzed arteries. A dose of 150–300 mg should be given as soon as possible after the onset of symptoms […] The in-hospital mortality rate from AMI is now less than 10%, with most deaths occurring within the first few hours, often due to ventricular fibrillation (VF).”

Cardiogenic shock is a low-cardiac output state with clinical evidence of inadequate blood flow. It has been defined clinically as a syndrome characterized by hypotension (eg, systolic blood pressure <90 mmHg or 30 mmHg less than normal) or evidence of reduced tissue blood flow (eg, cold clammy skin, urine output <30 mL/h, confusion). […] Most cases of cardiogenic shock are caused by severe left ventricular failure, and will present with pulmonary edema […] The mortality rate of cardiogenic shock overall is around 80%, although this improves to approximately 50% in patients with a surgically correctable lesion. Many survivors are left with significant cardiac pathology such as angina or limiting heart failure.”

“The lungs have two major functions: to provide adequate arterial oxygenation for tissue needs and to eliminate CO2. These two functions are largely independent of each other. Respiratory failure can be classified according to the underlying pathophysiologic derangement. All types of respiratory failure may present with arterial hypoxemia and/or arterial hypercapnia.”

“In the normal resting state, 1–5% of the cardiac output is delivered to the respiratory muscles. This can increase up to tenfold in patients with shock and respiratory distress. Mechanical ventilation allows resting of the respiratory muscles.”

“Patients who have been ventilated for brief periods of time (eg, overnight ventilation following major surgery) may be liberated from mechanical ventilation rapidly […] This is in marked contrast to patients who have been critically ill for long periods of time (days), in whom the process of withdrawing ventilatory support is often protracted. Day-to-day changes in the patient’s condition during this period of respiratory convalescence often necessitate the temporary reintroduction of more substantial mechanical ventilatory support.”

“ARDS is a syndrome causing acute respiratory failure characterized by severe hypoxemia, poorly compliant (‘stiff ’) lungs, and diffuse patchy infiltration on the chest X-ray in patients in whom cardiogenic pulmonary edema has been excluded. Rather than being an isolated condition, it is recognized as the pulmonary manifestation of systemic inflammation. ARDS is now recognized as the extreme end of a spectrum of ALI [Acute Lung Injury, US – though see also this], and is defined in terms of the severity of the gas exchange defect […] The mortality rate of ARDS ranges from 30% to 40%, and has improved significantly in recent years with the advent of new ventilator strategies.”

“Pneumonia can be defined as an acute lower respiratory tract illness, which is associated with fever, symptoms and signs in the chest, and abnormalities on the chest X-ray. In patients admitted to the hospital, it carries an overall mortality of about 10%. Mortality is strongly correlated with age, chronic comorbidities, severely abnormal vital signs upon presentation, and laboratory abnormalities (eg, pH, blood urea nitrogen, Na+, glucose, hemoglobin, and PaO2).”

“[Hospital-acquired (nosocomial) pneumonia] is defined as pneumonia developing more than 2 days after admission to hospital. It is particularly common in the ICU and postoperative patients, and carries a mortality rate of up to 50%. […] Diagnosis often proves difficult, particularly in ventilated patients, because features are nonspecific and may be confused with other conditions ”

“Pulmonary embolism (PE) occurs in 15–20 patients per 1,000 of the general hospital population, of which 2–5 cases are fatal. At least 50% of patients who die from PE have had some indication of thromboembolism within the preceding 7 days. Failure to diagnose PE has adverse consequences, since 30% of patients with untreated PE die compared with 8% of treated PE. […] Pulmonary emboli usually result from the formation of asymptomatic deep vein thromboses (DVTs) in deep veins of the lower limbs, pelvis, and abdomen. Upper extremity DVTs are usually associated with indwelling catheters and may account for up to 15% of DVTs. […] Factors promoting the formation of thrombi are described by Virchow’s triad of venous stasis, abnormal vessel walls, and increased coagulability […] Thrombolytic therapy is indicated for massive PE with associated shock. Its role in massive PE, with echocardiographic evidence of right heart failure or massive PE with severe pulmonary hypertension, has demonstrated improved secondary outcomes compared with heparin, though no survival benefit has been noted. Allergic reactions and hemorrhage are the principal complications of thrombolytics, and restrict their use considerably.”

August 25, 2013 Posted by | books, data, health care, medicine | Leave a comment

Stuff

i. PlosOne: Underestimating Calorie Content When Healthy Foods Are Present: An Averaging Effect or a Reference-Dependent Anchoring Effect?

“Previous studies have shown that estimations of the calorie content of an unhealthy main meal food tend to be lower when the food is shown alongside a healthy item (e.g. fruit or vegetables) than when shown alone. This effect has been called the negative calorie illusion and has been attributed to averaging the unhealthy (vice) and healthy (virtue) foods leading to increased perceived healthiness and reduced calorie estimates. The current study aimed to replicate and extend these findings to test the hypothesized mediating effect of ratings of healthiness of foods on calorie estimates. […] The first two studies failed to replicate the negative calorie illusion. In a final study, the use of a reference food, closely following a procedure from a previously published study, did elicit a negative calorie illusion. No evidence was found for a mediating role of healthiness estimates. […] The negative calorie illusion appears to be a function of the contrast between a food being judged and a reference, supporting the hypothesis that the negative calorie illusion arises from the use of a reference-dependent anchoring and adjustment heuristic and not from an ‘averaging’ effect, as initially proposed. This finding is consistent with existing data on sequential calorie estimates, and highlights a significant impact of the order in which foods are viewed on how foods are evaluated.” […]

The basic idea behind the ‘averaging effect’ above is that your calorie estimate depends on how ‘healthy’ you assume the dish to be; the intuition here is that if you see an apple next to an icecream, you may think of the dish as more healthy than if the apple wasn’t there and that might lead to faulty (faultier) estimates of the actual number of calories in the dish (incidentally presumably such an effect is possible to detect even if people correctly infer that the latter dish has more calories than does the former; what’s of interest here is the estimate error, not the actual estimate). These guys have a hard time finding a negative calorie illusion at all (they don’t in the first two studies), and in the case where they do the mechanism is different from the one initially proposed; it seems to them that the story to be told is a story about anchoring effects. I like when replication attempts get published, especially when they fail to replicate – such studies are important. Here are a few more remarks from the study, about ‘real-world implications’:

“Calorie estimates are a simple measure of participant’s perception of foods; however they almost certainly do not reflect actual factual knowledge about a food’s calorie content. It is not currently known whether calorie estimates are related to the expected satiety for a food, or anticipated tastiness. The data from the current studies fail to show that calorie estimates are derived directly from the healthiness ratings of foods. Other studies have shown that calorie estimates are influenced by the restaurant from which a food is purchased [12], as well as the order in which foods are presented [current study, 11], very much supporting the contextually sensitive nature of calorie estimates. And there is some evidence that erroneous calorie estimates alter portion size selection [13] and that lower calorie estimates for a main meal item have been shown to alter selection for drinks and side dishes [12].

Based on the current data, a negative calorie illusion is unlikely to be driving systematic failures in calorie estimations when incidental “healthy foods”, such as fruit and vegetables, are viewed alongside energy dense nutrition poor foods in advertisements or food labels. Foods would need to be viewed in a pre-determined sequence for systematic errors in real-world instances of calorie estimates. A couple of examples when this might occur are when food items are viewed in a meal with courses (starter, main, dessert) or when foods are seen in a specified order as they are positioned on a food menu or within the pathway around a supermarket from the entrance to the checkout tills.”

ii. A couple of reddit book lists that may be of interest: AskHistorians book list. AskAnthropology reading list. I’ve added a couple of books from those lists to my to-read list.

iii. You can read some pages from Popper’s Conjectures and Refutations here. A few quotes:

“I found that those of my friends who were admirers of Marx, Freud, and Adler, were impressed by a number of points common to these theories, and especially by their apparent explanatory power. These theories appeared to be able to explain practically everything that happened within the fields to which they referred. The study of any of them seemed to have the effect of an intellectual conversion or revelation, opening your eyes to a new truth hidden from those not yet initiated. Once your eyes were thus opened you saw confirming instances everywhere: the world was full of verifications of the theory. Whatever happened always confirmed it. Thus its truth appeared manifest; and unbelievers were clearly people who did not want to see the manifest truth; who refused to see it, either because it was against their class interest, or because of their repressions which were still ʺun‐analysedʺ and crying aloud for treatment.

The most characteristic element in this situation seemed to me the incessant stream of confirmations, of observations which ʺverifiedʺ the theories in question; and this point was constantly emphasized by their adherents. A Marxist could not open a newspaper without finding on every page confirming evidence for his interpretation of history; not only in the news, but also in its presentation ‐ which revealed the class bias of the paper ‐ and especially of course in what the paper did not say. The Freudian analysts emphasized that their theories were constantly verified by their ʺclinical observations.” […] I could not think of any human behaviour which could not be interpreted in terms of either theory [Freud or Adler]. It was precisely this fact ‐ that they always fitted, that they were always confirmed ‐ which in the eyes of their admirers constituted the strongest argument in favour of these theories. It began to dawn on me that this apparent strength was in fact their weakness. […]

These considerations led me in the winter of 1919 ‐ 20 to conclusions which I may now reformulate as follows.
(1) It is easy to obtain confirmations, or verifications, for nearly every theory ‐ if we look for confirmations.
(2) Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory ‐ an event which would have refuted the theory.
(3) Every ʺgoodʺ scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
(4) A theory which is not refutable by any conceivable event is nonscientific. Irrefutability is not a virtue of theory (as people often think) but a vice.
(5) Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability; some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
(6) Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of ʺcorroborating evidence.ʺ)
(7) Some genuinely testable theories, when found to be false, are still upheld by their admirers ‐ for example by introducing ad hoc some auxiliary assumption, or by re‐interpreting theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a ʺconventionalist twistʺ or a ʺconventionalist stratagem.ʺ)

One can sum up all this by saying that the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.”

iv. A couple of physics videos:

v. The hidden threat that could prevent Polio’s global eradication.

“Global eradication of polio has been the ultimate game of Whack-a-Mole for the past decade; when it seems the virus has been beaten into submission in a final refuge, up it pops in a new region. Now, as vanquishing polio worldwide appears again within reach, another insidious threat may be in store from infection sources hidden in plain view.

Polio’s latest redoubts are “chronic excreters,” people with compromised immune systems who, having swallowed weakened polioviruses in an oral vaccine as children, generate and shed live viruses from their intestines and upper respiratory tracts for years. Healthy children react to the vaccine by developing antibodies that shut down viral replication, thus gaining immunity to infection. But chronic excreters cannot quite complete that process and instead churn out a steady supply of viruses. The oral vaccine’s weakened viruses can mutate and regain wild polio’s hallmark ability to paralyze the people it infects. After coming into wider awareness in the mid-1990s, the condition shocked researchers. […] Chronic excreters are generally only discovered when they develop polio after years of surreptitiously spreading the virus.”

Wikipedia incidentally has a featured article about Poliomyelitis here.

August 24, 2013 Posted by | medicine, papers, philosophy, Physics, Psychology, random stuff, science | Leave a comment

A Dance With Dragons (ii) (no spoilers)

I finished the book today. It’s taken a bit of time to finish it because I put it away for a while after reading half of it. I should point out that I did so not because I disliked the book; rather the problem was the opposite, it was great but it was taking up time I figured I ought to be spending in a different manner.

I liked it much better than the 4th book, and I gave it five stars on goodreads. This is good stuff. I’m looking forward to the 6th book in the series, but I may have to wait a while for that one. Don’t let the page-count scare you away from reading these books – I should remind you that I read all of the books in this series this summer (on top of a lot of other stuff), and I’d hardly call myself a particularly fast reader.

I haven’t quoted much from the book, but I figured I should add at least a few quotes. The four quotes below will give you a little information about how the book is written, but they will tell you next to nothing else – at least nothing which could conceivably spoil the reading (-watching?) experience. All names have been removed and I do belive I’ve been very careful to avoid giving anything at all away here:

“”So many years, so many wars, so many kings … you’d think someone would have made a peace.”
“Someone did, my lord. Many someones. We’ve had a hundred peaces with the [others], many sealed with marriages. […] But then some fresh quarrel broke out, and the old wounds opened and began to bleed again. That’s how it always happens, my father says. So long as men remember the wrongs done to their forebears, no peace will ever last. So we go on century after century, with us hating the [others] and them hating us. My father says there will never be an end to it.”
“There could be.”
“How, my lord? The old wounds never heal” […]
“Never wound a foe when you can kill him. Dead men don’t claim vengeance.”
“Their sons do,” […]
“Not if you kill the sons as well.””

“”You cannot trust in sellswords.”
“They are men like any other men. They want gold, glory, power. That’s all I am trusting in.””

“The most insidious thing about bondage was how easy it was to grow accustomed to it. The life of most slaves was not all that different from the life of a serving man [in Westeros], it seemed […] Slaves were chattels, aye. They could be bought and sold, whipped and branded, used for the carnal pleasure of their owners, bred to make more slaves. In that sense they were no more than dogs or horses. But most lords treated their dogs and horses well enough. Proud men might shout that they would sooner die free than live as slaves, but pride was cheap. When the steel struck the flint, such men were rare as dragon’s teeth; elsewise the world would not have been so full of slaves. There has never been a slave who did not choose to be a slave. […] Their choice may be between bondage and death, but the choice is always there.

“”You cannot marry her. She has a husband.”
“She does not love [her husband].”
“What has love to do with marriage? [You] should know better.”

August 23, 2013 Posted by | books | Leave a comment

Quotes

i. “Without the aid of statistics nothing like real medicine is possible.” (Pierre Charles Alexandre Louis)

ii. “Before the eighteenth century the demographic impact of the profession of medicine remained negligible. Relatively few persons could afford to pay a doctor for his often very expensive services; and for every case in which the doctor’s attendance really made a difference between life and death, there were other instances in which even the best available professional services made little difference to the course of the disease, or actually hindered recovery. …Only with the eighteenth century did the situation begin to change; and it was not until after 1850 or so that the practice of medicine and the organization of medical services begin to make large-scale differences in human survival rates and population growth.” (William Hardy McNeill, Plagues and Peoples)

iii. “The unbiased opinion of most medical men of sound judgment and long experience … [holds that] the amount of death and disaster in the world would be less, if all disease were left to itself.” (Harvard professor Jacob Bigelow, 1835).

iv. “No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavors to establish.” (David Hume)

v. “If you hide your ignorance, no one will hit you, and you’ll never learn.” (Ray Bradbury)

vi. “It doesn’t matter who you are. You mustn’t go around saying who you are, or else you get captured by the mask of false identity. It’s the work that identifies you.” (-ll-)

vii. “Whereas back then I wrote about the tyranny of the majority, today I’d combine that with the tyranny of the minorities. These days, you have to be careful of both.” (-ll-)

viii. “What you would seem to be, be really.” (Benjamin Franklin)

ix. “He’s a Fool that cannot conceal his Wisdom.” (-ll-)

x. “The Sting of a Reproach, is the Truth of it.” (-ll-)

xi. “We are not so sensible of the greatest Health as of the least Sickness.” (-ll-)

xii. “Lost Time is never found again.” (-ll-)

xiii. “Most Fools think they are only ignorant.” (-ll-)

xiv. “Many a Man thinks he is buying Pleasure when he is really selling himself a Slave to it.” (-ll-)

xv. “It is the mind which creates the world around us, and even though we stand side by side in the same meadow, my eyes will never see what is beheld by yours, my heart will never stir to the emotions with which yours is touched.” (George Gissing. Related link.)

xvi. “Time is money — says the vulgarest saw known to any age or people. Turn it round about, and you get a precious truth — money is time. […] What are we doing all our lives but purchasing, or trying to purchase, time? And most of us, having grasped it with one hand, throw it away with the other.” (-ll-)

xvii. “A real failure does not need an excuse. It is an end in itself.” (Gertrude Stein)

xviii. “Everybody thinks that this civilization has lasted a very long time but it really does take very few grandfathers’ granddaughters to take us back to the dark ages.” (-ll-)

xix. “The world is made up, for the most part, of fools and knaves, both irreconcileable foes to truth.” (George Viliers, 2nd Duke of Buckingham)

xx. “People never want to be told anything they do not believe already.” (James Branch Cabell)

August 22, 2013 Posted by | quotes/aphorisms | Leave a comment

The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature

Here’s a link.

I’ve read roughly half the book. It’s interesting, but quite speculative. As with all popular science books it sort of assumes the reader doesn’t know very much about anything, and this of course means that there’s quite a bit of known stuff covered here along the way. The notes/references do quite a bit of the work. So far I’ve enjoyed reading the book, but I’m not that impressed; I’m probably currently at a three-star evaluation, but a little closer to four than two. Compared to a textbook it’s very easy to read.

Some quotes from the first half of the book:

“most experimental psychology views the human mind exclusively as a computer that learns to solve problems, not as an entertainment system that evolved to attract sexual partners.”

“Natural selection [refer] to competition within or between species that affect relative survival ability. Sexual selection [refer] to sexual competition within a species that affects relative rates of reproduction. […] Under natural selection, species adopt to their environments. […] Under sexual selection, species adapt too, but they adapt to themselves. Females adapt to males, males adapt to females. Sexual preferences adapt to the sexual ornaments available, and sexual ornaments adapt to sexual preferences.
This can make things quite confusing. In sexual selection, genes do not code just for the adaptions used in courtship, such as sexual ornaments. They also code for the adaptions used in mate choice, the sexual preferences themselves.”

“brain size within each sex is correlated about 40 percent with general intelligence” (I did not know that!)

“Short-term mating is exciting and sexy, but it is not necessarily where sexual selection has the greatest effect. Human females, much more than other great apes, conceal when they are ovulating. This means that a single act of short-term copulation rarely results in pregnancy. Almost all human pregnancies arise in sexual relationships that have lasted at least several months, if not years. Modern contraception has merely reinforced this effect. […] when it comes to choosing sexual partners for long-term relationships, men and women increase their choosiness to almost identical levels. They also converge in the features they prefer.”

“By suggesting that sexual selection plays a major but neglected role in evolutionary innovation in general and the human mind’s evolution in particular, I am proposing a sort of marketing revolution in biology. Survival is like production, and courtship is like marketing. Organisms are like products, and the sexual preferences of the opposite sex are like consumer preferences. Courtship displays are not a mysterious luxury soaking up excess energy after the business of survival is accomplished. Rather, they are the only way to get one’s genes into the next generation, by fullfilling the sexual preferences of the opposite sex. Survival only matters insofar as it contributes to courtship. If nobody wants to mate with an animal, there’s no evolutionary point in the animal surviving.”

“Our ancestors did not spend all their time worrying about survival problems. They were among the longest-lived species on the planet, which implies that their daily risk of death was miniscule. Like most great apes, they probably spent their time worrying about social and sexual problems.”

“In most primate species, the distribution of food in the environment determines the distribution of females, and the distribution of females determines the distribution of males. When food is so dispersed that females do best by foraging on their own, males disperse to pair up with the lone females. This gives rise to monogamous couples. It is a fairly rare pattern among primates […] When food comes in patches large enough for several females to share, they tend to band together in small groups to find the food, and to protect each other against predators, unwanted males, and competing female groups. As long as the female band is not too large, a single male can exclude other males from sexual access to the band […] This ‘harem’ system of single-male polygyny is fairly common in primates. […] When food comes in still larger patches, female groups can grow too large for any single male to defend them. the males must then form coalitions, resulting in a complex multi-male, multi-female group […] Our hominid ancestors probably lived in such groups, in which sexual selection gets more complicated. […] Most children were probably born to couples who stayed together only a few years. Exclusive lifelong monogamy was practically unknown. The more standard pattern would have been ‘serial monogamy’: a sequence of nearly exclusive sexual partnerships that were socially recognized and jealously defended.” (This last part I consider to be highly speculative, and the notes/references are basically doing all the work here. Given the paucity of the available archaeological evidence – which I’m familar with – and the uncertainties involved when drawing conclusions and inferences based on the behaviours of other great apes, I think there’s a fair amount of uncertainty related to to which extent this account is true. There’s a lot we don’t know and can’t ever know about what was going on back then.)

“David Buss has amassed a lot of evidence that human females across many cultures tend to prefer males who have high social status, good income, ambition, intelligence, and energy – contrary to the views of some cultural anthropologists, who assume that people vary capriciously in their sexual preferences across different cultures. […] [It is a] universal, cross-cultural pattern that men care more about a partner’s age than women do, men generally preferring partners younger than themselves, and women generally preferring partners older than themselves. […] There is strong evidence from evolutionary psychology that men in modern societies generally prefer the physical appearance of women around 20 years old to those who are older (or younger). […] there has been much less research on the age at which women’s minds are most attractive.”

“our ancestors were highly social primates living in groups with children, relatives, and friends. Sexual relationships began and ended within family and tribal contexts.
If mate choice favours good genes, it can be useful to meet a potential mate’s blood relatives, because they share some of the same genes. An individual’s kin give additional information about their heritable fitness. If an intelligent man has foolish brothers or a beautiful woman has ugly sisters, this may lower their attractiveness as potential partners […] Given two sexual prospects who appear to display equal fitness, the one whose relatives appear healthier, brighter, more attractive, more fertile, and more successful probably has higher actual fitness. Since our ancestors tended to live in kin groups, there were plentiful opportunities for mate choice to take into account this sort of kin equality.”

August 21, 2013 Posted by | anthropology, books, evolution | 3 Comments

Mechanism and Causality in Biology and Economics

First, here’s a link. Some quotes below, some comments in the last part of the post:

“I refer to an account of causal order based on Simon’s seminal analysis as the structural account.2 It is structural in the sense that what matters for determining the causal order is the relationship among the parameters and the variables and among the variables themselves. The parameterization – that is, the identification of privileged set of parameters that govern the functional relationships – is the source of the causal asymmetries that define the causal order. The idea of a privilege parameterization can be made more precise, by noting that a set of parameters is privileged when its members are, in the terminology of the econometricians, variation-free. A parameter is variation-free if, and only if, the fact that other parameters take some particular values in their ranges does not restrict the range of admissible values for that parameter.
Defining parameters as variation-free variables has a similar flavor to Hans Reichenbach’s (1956) Principle of the Common Cause: any genuine correlation among variables has a causal explanation – either one causes the other, they are mutual causes, or they have a common cause. Since we represent causal connections as obtaining only between variables simpliciter,we insist that parameters not display any mutual constraints. […] the variation-freeness of parameters is only a representational convention. Any situation in which it appears that putative parameters are mutually constraining can always be rewritten so that the constraints are moved into the functional forms that connect variables to each other.” […]

“John Anderson’s (1938, p. 128) notion of a causal field is helpful (see also Mackie 1980, p. 35; Hoover 2001, pp. 41–49). The causal field consists of background conditions that, for analytical or pragmatic reasons, we would like to set aside in order to focus on some more salient causal system. We are justified in doing so when, in fact, they do not change or when the changes are causally irrelevant. In terms of representation within the structural account, setting aside causes amounts to fixing certain parameters to constant values. The effect is not unlike Pearl’s or Woodward’s wiping out of a causal arrow, though somewhat more delicate. The replacement of a parameter by a constant amounts to absorbing that part of the causal mechanism into the functional form that connects the remaining parameters and variables.” (From chapter 3, ‘Identity, Structure, and Causal Representation in Scientific Models’. This was one of the better chapters).

“Certain substantial idealisations need to be taken also when the RD model [replicator dynamics model, US] is interpreted biologically. A different set of substantial idealisations needs to be taken when the RD model is interpreted socially. By making these different idealisations, we adapt the model for its respective representative uses. This is standard scientific practice: most, and possibly all, model uses involve idealisations. Yet when the same formal structure is employed to construct different, more specific mechanistic models, and each of these models involves different idealisations, one has to be careful when inferring purported similarities between these different mechanisms based on the common formal structure. […] the RD equation is adapted for its respective representative tasks. In the course of each adaptation, certain features of the RD are drawn on – others are accepted as useful or at least harmless idealisations. Which features are drawn on and which are accepted as idealisations differ with each adaptation. The mechanism that each adaptation of the RD represents is substantially different from each other and does not share any or little causal structure between each other.” (From Chapter 5: ‘Models of Mechanisms: The Case of the Replicator Dynamics’).

“Before formulating [a] claim, it is necessary first to clear up some terminology. Leuridan[‘s] definition ignores three traditional distinctions that have brought much-needed clarity to the discussions of laws in the philosophy of science. First, we distinguish laws (metaphysical entities that produce or are responsible for regularities) and law statements (descriptions of laws). If one does not respect this distinction, one runs the risk (as Leuridan does) of unintentionally suggesting that sentences, equations, or models are responsible for the fact that certain stable regularities hold. In like fashion, we distinguish regularities, which are statistical patterns of dependence and independence among magnitudes, from generalizations, which describe regularities. Finally, we distinguish regularities from laws, which produce or otherwise explain the patterns of dependence and independence among magnitudes (or so one might hold). […]

Strict law statements, as Leuridan understands them, are nonvacuous, universally quantified, and exceptionless statements that are unlimited in scope, apply in all times and places, and contain only purely qualitative predicates (2010, p. 318). Noting that few law statements in any science live up to these standards, Leuridan argues that the focus on strict law statements (and presumably also on strict laws) is unhelpful for understanding science. Instead, he focuses on the concept of a pragmatic law (or p-law). Following Sandra Mitchell (1997, 2000, 2003, 2009), Leuridan understands p-law statements as descriptions of stable and strong regularities that can be used to predict, explain, and manipulate phenomena. A regularity is stable in proportion to the range of conditions under which it continues to hold and to the size of the space-time region in which it holds (2010, p. 325). A regularity is strong if it is deterministic or frequent. p-law statements need not satisfy the criteria for strict law statements.” (From chapter 7: ‘Mechanisms and Laws: Clarifying the Debate’)

“This section has illustrated two central points concerning extrapolation. First, it is not necessary that the causal relationship to be extrapolated is the same in the model as in the target. Given knowledge of the probability distributions for the model and target along with the selection diagram, it can be possible to make adjustments to account for differences. Secondly, the conditions needed for extrapolation vary with the type of claim to extrapolated. In general, the more informative the causal claim, the more stringent the background assumptions needed to justify its transfer. This second point is very important for explaining how extrapolation can remain possible even when substantial uncertainty exists about the selection diagram. […]

I should emphasize that the point here is definitely not to insist upon the infirmity of causal inferences grounded in extrapolation and observational data. Uncertainties frequently arise in experiments too, especially those involving human subjects (for instance, due to noncompliance, i.e., the failure of some subjects in the experiment to follow the experimental protocol). Such uncertainties are inherent in any attempts to learn about causation in large complex systems wherein numerous practical and ethical concerns restrict the types of studies that are possible. Consequently, scientific inference in such situations usually must build a cumulative case from a variety of lines of evidence none of which is decisive in isolation. Although that may seem a rather obvious point, it does seem to get overlooked in some critical discussions of extrapolation. […] critiques which observe that extrapolations rarely if ever constitute definitive evidence sail wide of the mark. Building a case based on the coherence of multiple lines of imperfect evidence is the norm for social science and other sciences that study complex systems that are widely diffused across space and time. To insist otherwise is to misconstrue the nature of science and to obstruct applications of scientific knowledge to many pressing real-world problems.” (From chapter 10: ‘Mechanisms and Extrapolation in the Abortion-Crime Controversy’.)

“In 1992, Heckman published a seminal paper containing ‘most of the standard objections’ against randomised experiments in the social sciences. Heckman focused on the non-comparative evaluation of social policy programmes, where randomisation simply decided who would join them (without allocating the rest to a control group). Heckman claimed that even if randomisation allows the experimenters to reduce selection biases, it may produce a different bias. Specifically, experimental subjects might behave differently if joining the programme did not require ‘a lottery’. Randomisation can thus interfere with the decision patterns (the causes of action) presupposed in the programme under evaluation. […] Heckman’s main objection is that randomisation tends to eliminate risk-averse persons. This is only acceptable if risk aversion is an irrelevant trait for the outcome under investigation […] However, even if irrelevant, it compels experimenters to deal with bigger pools of potential participants in order to meet the desired sample size, so the exclusion of risk-averse subjects does not disrupt recruitment. But bigger pools may affect in turn the quality of the experiment, if it implies higher costs. One way or another, argues Heckman, randomisation is not neutral regarding the results of the experiment.” (…known stuff, but I figured I should quote it anyway as it’s unlikely that all readers are familiar with this problem. From chapter 11: ‘Causality, Impartiality and Evidence-Based Policy’. How to deal with the problem? Here’s what they conclude:)

“To sum up, in RFEs [Randomized Field Experiments – US], randomisation may generate a self-selection bias; we can only avoid with a partial or total masking of the allocation procedure. We have argued that this is a viable solution only insofar as the trial participants do not have strong preferences about the trial outcome. If they do, we cannot assume that blinded randomisation will be a control for their preferences unless we test for its success. We will only be able to claim that the trial has been impartial regarding the participants’ preferences if we have a positive proof of them being ignorant of the comparative nature of the experiment. Hence, in RFEs, randomisation is not a strong warrant of impartiality per se: we need to prove in addition that it has been masked successfully.1”

On a general note, I found some of the stuff in this book interesting, but there was some confusing stuff in there as well. I had at least some background knowledge about quite a few of the subjects covered, but a lot of the stuff in the book is written by people with a completely different background (many of the contributors are philosophers of science), and in some chapters I had a hard time ‘translating’ a specific contributor’s (gibberish? It’s not a nice word to use, but I’m tempted to use it here anyway) into stuff related to the science/the real world – I was quite close to walking away from the book while reading chapters 8 and 9, dealing with natural selection and causal processes. I didn’t, but you should most certainly not pick up this book in order to figure out how natural selection ‘actually works’; if that’s your goal, read Dawkins instead. A few times I had an ‘I knew this, but that’s actually an interesting way to think about it’-experience and I generally like having those. As in all books with multiple contributors, there’s some variation in the quality of the material across chapters – and as you might infer from the comments above, I didn’t think very highly of chapters 8 and 9. But there were other chapters as well which also did not really interest me much. I did read it all though.

Overall I’m a little disappointed, but it’s not all bad. I gave it 2 stars on goodreads, and towards the end I moved significantly closer to the 3 star rating than the one star rating. I wouldn’t recommend it though; considering how much you’re likely to get out of this, it’s probably for most people simply too much work – it’s not an easy book to read.

August 19, 2013 Posted by | books, economics, philosophy, science, statistics | Leave a comment

Mensa

After a long time of badgering (I shall not mention any names – Miao…), a month or two ago I was finally talked into signing up for an admissions test to Mensa in order to see if I could get in. I took the test last week and I received the results today. I got 44 out of the 45 questions correct, corresponding to an IQ performance in the top 1 % and an IQ of 135 (using a standard deviation of 15). So I’m in if I want to be.

This is of course a great opportunity for me to expand my social network and meet new people, and I’ll give it a try.

In unrelated news, currently the FIDE World Cup 2013 is being played in Tromsø, Norway. Official site here, live coverage here. Of particular interest I think is the young Chinese player Yi Wei. He’s only fourteen years old, yet he’s defeated both Ian Nepomniachtchi and Alexei Shirov – outplaying Shirov completely yesterday – and he has now moved on to the third round. This is crazy! He won’t win this event, but I’m thinking this is a player who’ll go far.

Update – documentation added below, in case some readers are skeptical (people often lie about such things, especially online…). It’s in Danish, but at least you can verify that all the numbers reported above are in the document (44, 45, 1 %, 135, 15):

DSCN3693

(The ’empty box’ I added in MS Paint in order to obscure my name and birth date).

August 16, 2013 Posted by | Chess, IQ, personal | 9 Comments

A Dance with Dragons (I) (no spoilers)

“The man is cold, brooding, sullen, deaf to humor. And those are his good points.”

“What has this poor child done to you that you would wish her dead?” […] “Queen her, I said. Not kill her.” […] “To queen her is to kill her.”

“Tales are told of you […] I hear them everywhere. People fear you.”
“Good.”
“You are mistaken. It is not good. No tales were ever told of me. Do you think I would be sitting here if it were otherwise? Your amusements are your own, I will not chide you on that count, but you must be more discreet.”

“He’s not afraid of anyone, m’lord.”
“He should be. Fear is what keeps a man alive in this world of treachery and deceit.”

“When treating with liars, even an honest man must lie.”

“Give me priests who are fat and corrupt and cynical […] It’s the ones who believe in gods who make the trouble.”

“”His Grace is not an easy man. Few are, who wear a crown. Many good men have been bad kings […] and some bad men have been good kings.”

“That sweet man does not mean to take us to Mereen. He was too quick to accept your offer. He’ll take thrice the usual fee, no doubt, and once he has us aboard and out of sight of land, he’ll slit our throats and take the rest of our gold as well.”

I was recently reminded that I still had one book to go in this series, and as mentioned before I’ve sort of decided I want to read/finish the series this summer. The part of the series which has been written and published at this point, anyway. I’ve read roughly the first 600 pages over the last couple of days, meaning that I’m a little more than halfway through the book. I like it much better than A Feast for Crows – unless the second half of this book turns out to be very disappointing, I’ll probably give it 5 stars on goodreads.

August 15, 2013 Posted by | books | Leave a comment

Stuff

i. How To Write Badly Well. The blog is no longer active, but there’s a lot of good stuff in the archives. A collection of good links here. Some posts from the blog that made me smile or laugh: Choose a narrator who is peripheral to the story, Select words for their impressiveness rather than their relevance, Find the bone mote, Let your characters explain themselves, Underestimate your audience.

ii. Preschool Children’s Behavioral Tendency toward Social Indirect Reciprocity.

“The tendency for genetically unrelated individuals to build large-scale cooperative networks in human societies is a major exception in the animal kingdom [1]. Researchers have suggested that the principle of indirect reciprocity–the idea that altruistic (or prosocial) behavior toward an individual is returned by another individual–is crucial in enabling these cooperative networks [2], [3]. Three different forms of indirect reciprocity exist: social indirect (downstream) [4][6], generalized (upstream) [7], [8], and generalized indirect [3]. In this study, we focus on social indirect reciprocity (SIR), which means that if A helps B, then C will help A, who acted cooperatively toward B; this is based on individuals’ evaluations of others’ prior behaviors toward third parties [4][6]. SIR is associated with social evaluation or moral judgment in humans and seems to be most important form for human prosociality. SIR is more elaborate than the other two forms of indirect reciprocity and requires individuals to recognize and select those with whom they cooperate [2], [3]. Through computer simulations and analytic models, previous studies have demonstrated that SIR could evolve when individuals act according to particular strategies [2], [6]. In all such strategies, individuals have the tendency (1) to reward helpful individuals and (2) to detect and avoid helping cheaters [2], [6].

In reality, studies with human adults have demonstrated a behavioral tendency toward SIR in the decision to cooperate or defect in game experiments [9], [10]. However, there are relatively few studies on SIR in children. Therefore, investigating whether young children have a tendency toward SIR, as well as the manner in which such reciprocity develops during the early developmental stages, will help us understand how and when this tendency, that is so fundamental in organizing cooperative interactions between adults, takes root in people’s lives.

Prosocial behavior can be observed from the first year of a child’s life [11] and becomes common between ages 1 and 2 [12]. Additionally, even 14-month-olds have been shown to be capable of helping others achieve their goals [13]. However, this early prosocial tendency does not seem to be selective with regard to recipients [14], [15]. Such selectivity begins to appear between toddlerhood and the preschool period. For example, prosocial behavior becomes selective in terms of partners’ gender and personality [11], [16], familiarity between partners [17], [18], or the existence of prior prosocial behavior from the partners, thereby suggesting that children engage in direct reciprocity [19][23]. However, this selectivity is based on the partners’ own characteristics or behavior toward the potential helper itself. In order to build cooperative relationships through SIR, children require a more elaborate selective ability based on the social evaluation of a partner’s behavior toward a third party. […]

In this study, we investigated whether preschool children, in their natural interactions, have a tendency to behave prosocially or affiliatively toward a peer after they have directly observed the peer behaving prosocially toward a third party. The results showed that bystanders performed prosocial and affiliative behaviors toward focal children more frequently after the focal children’s prosocial behavior toward third parties, compared with control situations. This indicates that 5- to 6-year-olds have a behavioral tendency toward prosocial and affiliative behaviors according to the recipient peers’ prior prosocial behavior toward another peer. […] bystanders tended to engage in prosocial and affiliative behaviors toward peers more frequently soon after observing the peers’ prosocial behavior toward other peers than in control situations, even when the possibility that bystanders had imitated the first recipient’s or other bystanders’ prosocial behavior was eliminated. […]

we conclude that preschool children have an essential behavioral tendency to establish SIR when interacting with their peers in naturalistic settings, as well as in their interactions with puppets or adult actors, as found in previous studies [27][29]. Our results, which extend the findings of previous studies [27][29], suggest that preschool children not only have the ability to evaluate partners on the basis of their prosocial behavior toward a third party, they can also use this ability in natural interactions with their peers. This study is the first to provide evidence indicating that children’s prosocial interactions can be formed for the benefits derived from exchanging prosocial behaviors according to the mechanism of SIR in natural interactions with their peers. […]

SIR arises from two aspects of motivation: reward helpful individuals and avoid helping (or punish) harmful individuals [2], [4][6]. The present study explored only the behavioral tendency related to the former aspect and did not examine the latter. Previous studies have demonstrated that a “negativity bias” (a greater impact of negative information as compared with positive information) affects the behavioral tendencies of infants [24], [28], [66]. Vaish et al. [28] has shown that 3-year-olds’ prosocial behavior decreased toward a harmful individual but did not increase toward a helpful individual. Negativity bias has also been demonstrated in nonhuman primate: capuchin monkeys avoided non-reciprocal and non-helpful individuals with intentionality rather than express a preference for reciprocal or helpful ones [63], [64].”

iii. Benford’s very strange law:

I don’t actually think this lecture is all that great, but I watched it all and figured I might as well blog it. I think I’ve written about it before, I’ve certainly read about it before. Here’s wikipedia on the subject.

iv. I couldn’t help noticing the results of a new study suggesting that alcohol consumption (/during adolescence?) may be a significant risk factor for young-onset dementia (note the hazard ratio). I assume the study will be put up on the author’s website at some point – I’m annoyed I can’t access it yet.

This is a huge study (n=488,484), so it’s the kind of thing you’ll want to check out if you want to know more about this topic. Alcohol consumption has incidentally been linked to mental decline and dementia risk for a very long time, see e.g. this publication from around the year 2001.

v. A little stuff about mitochondrial DNA and related matters, via John Hawks. Do watch the video – it’s not long. Perhaps not surprisingly, Dawkins covered related stuff in The Ancestor’s Tale.

vi. In one of his recent posts, Ed Yong tells you a little about what happens inside you when a mosquito bites.

vii. Eyjafjallajökull and 9/11: The Impact of Large-Scale Disasters on Worldwide Mobility. I’ve only just briefly skimmed this, but it looks interesting. A quote:

“We model the impact of Eyjafjallajökull and 9/11 on the WAN [worldwide air transportation network] by removing the same set of airports that were closed in response to these events (see Text S1 Sec. S2.1) together with the non-stop flights to and from these airports. Our method captures the dynamic re-routing of passengers at functional airports to avoid obstructed multi-stop connections through airports that close. At their peak, on April 16th 2010, the closures due to Eyjafjallajökull’s ash cloud interrupted 20.5% of the total traffic and closed 10.5% of all airports. The closure of American and Canadian airspace as a response to the 9/11 attacks was even more severe, removing 37.7% of air traffic and 19.6% of all airports.”

August 13, 2013 Posted by | biology, Lectures, mathematics, papers | Leave a comment

The Knowledgeable Patient: Communication and Participation in Health (A Cochrane Handbook)

Here’s the link.

The book wasn’t particularly good (I gave it a 2 star rating on goodreads) and I didn’t spend much time on it, so I also don’t plan on spending much time on it here. There’s too much fluff and too little hard data for it to be all that interesting to me. This is not to say that it’s not a research-oriented book; it very much is, but apparently communication research at this stage is, well, yeah… There’s a lot of stuff here, but a lot of it wasn’t particularly interesting. I’d expected more from a Cochrane Handbook.

Anyway, some quotes (my bold):

“communication-related difficulties affect not only people’s feelings but also the quality, efficacy and safety of the medical and surgical treatments […] attempts to overcome the difficulties are more than just feel-good strategies. Rather, they are critical to improving people’s health and ensuring that medical mistakes are avoided. […] Communication failures can cause not only dissatisfaction but serious adverse events (an ‘injury caused by medical care’ [19]). In 2008–2009, the report on such events in Victorian hospitals identified that communication was a contributing factor in 20% of these events, with health information a factor in another 8% of cases [20]. […]

A study of 1308 complaints made at a major South Australian hospital over a 30-month period found that fully 45% (n = 621) of complaints were about communication problems […] Poor communication is known to be a key contributing factor in litigation
against primary care physicians [28]. […]

There is a long recorded history in research indicating that patients want more information than they receive. […] There is clear evidence that people want more information than they are given and that clinicians tend to overestimate the amount of information they have provided [15,16]. Roter and Makoul have noted that only 58% of people studied said their healthcare provider told them things in a way they could understand [17]. […]

People are usually presented as the recipients of information and communication, such as advice on what to do to keep healthy, get screened, take up needed healthcare and so on. The importance of information coming from consumers or the reality of many consumers communicating with each other does not receive the same attention.
Analysis of thousands of interventions for communication and participation in fact identifies that communication and participation can be readily conceived as multidirectional. […]

People cannot change risk factors unless they know about them, want to change them, understand how to change them and receive support and assistance in that process. This makes communication – and risk communication in particular – a key component of any strategy to reduce the impact of chronic disease, particularly where there are a number of known modifiable risk factors. […] Risk communication involves informing or educating people who are exposed to a risk factor (e.g. smoking) about their risk of disease. Information on the qualitative and quantitative dimensions of the risk may be presented with a view to enabling people to make decisions about changes in lifestyle or medications to reduce that risk [8]. A fundamental requirement for risk communication is to have concrete data from which to estimate the risk of an individual developing a disease. This is achieved by use of epidemiological research […] Risk communication is challenging for health professionals. General practitioners (GPs), and increasingly nurse practitioners, may be the first point of contact and information for many people. Apart from accurate calculation [10] and application to an individual patient, complex statistical concepts have to be communicated in ways that are easy to understand and motivating too [11]. Consumers’ existing understandings of risk information, their individual personal life circumstances [12] and individual preferences for the formats used to communicate risk [13, 14] add another level of complexity. This chapter presents findings from qualitative research into the views of health consumers and GPs on how risk for CVD should be discussed in consultations. […]

Percentages were frequently misunderstood by consumers [/patients, US], hampering their understanding of the degree of risk. […] Clear visual representations of risk assists comprehension [19]. […] Whilst GPs’ format preferences aligned with consumers, some felt that their patients did not respond well to numbers or charts. […] Reflecting other research findings, and highlighting their own experiences of consumers’ health literacy (or innumeracy), a number of GPs thought that the use of numbers, statistics, percentages, ratios and proportions was too difficult for some of their patients to understand or that their use might be confusing [25]. Several GPs also commented that since they did not understand particular numbers (such as odds) themselves, they would not expect that their patients would understand such measures accurately. […]

The people who expressed high levels of satisfaction with their experiences were those who felt that their physicians treated them as equals and that their treatment decision was made with input from both the physician and the patient. Positive health outcomes, including symptom resolution and pain control, have been linked to effective communication and agreement between the physician and the patient [8,9]. […]

Adverse events are incidents in which a patient experiences unintended harm while receiving medical treatment [1]. […] some may be due to treatment (e.g. prescribing or administering the wrong medicine or dosage), they may be known risks of a procedure (e.g. complications of a surgery or therapy) or they may be indirectly related to treatment (e.g. healthcare-acquired infection or exposure to a disease or disease risk). […] Communication following adverse events is especially sensitive and challenging. Doctors may be reluctant to apologise or inform patients that mistakes have occurred, as it may be seen as an admission of culpability and could raise liability concerns [4, 5]. Patients may suffer secondary harms, such as confusion, anxiety or distress, if poor communication strategies are used when disclosing information about adverse events, such as exposure to a disease risk [6]. […] When an adverse event has occurred in healthcare, people generally want to be informed [4, 11]. Even with the current increasing emphasis on open disclosure, there are indications that many adverse events remain unreported, and historically, this was often the case [4, 5, 11]. Several studies of people’s preferences for disclosure indicate that communication should contain detailed information, explaining the event, how it will affect them, what steps are being taken to prevent future occurrences of the same problem and, significantly, an expression of regret. People also want access to ongoing emotional support [4, 11]. […] People at risk, in general, would prefer to be notified of their risk status even if it is distressing [6, 12–14]. […]

Information found through individual research can […] be confusing or contradictory, as indicated by Glenton’s study on the information provided by government-run online health portals. Glenton and colleagues found that health portal information is rarely supported by systematic reviews, and is frequently confusing, vague or incomplete [20]. […]

Most of the reviews suggest that interventions to improve communication between clinicians and patients have only modest benefits on consultation processes and patient satisfaction. […]

There is no guarantee that evidence synthesised in a systematic review will lead to a clear conclusion. However, this does not make the review any less useful. As Light and Pillemer suggest, disagreements between research findings offer a valuable opportunity for the reader. Divergent outcomes may result from carrying out the same intervention in different settings, from an intervention being implemented differently or even different interventions sharing the same name. Exploring conflicting findings may teach the reader how to implement an intervention in their setting successfully in the future [1]. […] When confronted with the huge quantity and variable quality of available research, it may be tempting to take a short cut and use one study from a reputable journal to inform a decision. […] A health professional who looks at only a few of the individual BCN trials might have difficulty assessing their quality or comparing their results, and may reach a conclusion about the effectiveness of BCNs not actually supported by all the evidence. With a systematic review, all the available evidence is brought together in one place. Though this review shows no certain outcome for the intervention, it is preferable to know this, rather than basing future decisions and programmes on limited or poorer quality evidence. […]

The pharmaceutical industry alone accounts for 25% of the United Kingdom’s business investment in R&D […]

Whilst policy and supportive initiatives can increase patient involvement in setting research agendas, the question remains: does it make a difference? Indeed, there is some concern that involving non-researchers in the process may compromise research rigour in some way [15]. […]

At present, research evidence and the information materials derived from it for both doctors and consumers principally focus on one disease and largely ignore the interaction of diseases in patients’ lives [33]. This means that there may be little or no information for patients with multimorbidity to support treatment, self-management or other health actions [25, 27, 36]. There may also be little information that is suitable for doctors to share with their patients when multimorbidity is present. A further problem arises because it is not possible to simply apply what is known from research and information derived from single diseases to people with multimorbidity [12, 24]. […] although many interventions exist which might theoretically be able to help improve medicines use in multimorbidity, the reality is that the research evidence that evaluates these strategies does not consider, in most cases, issues of the growing number and complexity of medicines for multimorbidity. This means we have almost no research evidence to guide practice or policy on medicines in multimorbidity even though multimorbidity is a known risk factor for medicine-related adverse events [38]. […]

At its simplest, health literacy is the ability to seek, find, understand and use health information [3]. […] Health literacy can be built, but the effects of poorer literacy have been the focus of much of the research so far. […] Poorer health literacy is linked to more adverse events. […] People with limited health literacy are more likely to report their health as poor. They have poorer health outcomes [7, 8]. […]

In recent years, television and the internet have become the most important resources for health information [31, 32] […in China, US], with more than half of Chinese people gaining their health knowledge from television [31].”

August 11, 2013 Posted by | books, health care, medicine | Leave a comment

Promoting the unknown, a continuing series

i. This one is just wonderful (..mostly because I really love the setup with the rabbit – the performance isn’t flawless..):

ii.

iii.

iv.

v.

(Thank you for that one, Miao!)

I don’t know what the words mean, and I don’t care. You don’t need to understand the words to appreciate the music. This is wonderful stuff.

August 10, 2013 Posted by | music | Leave a comment

A few lectures

First, a link. I hadn’t heard about Gresham College until yesterday, so I’m assuming that some readers are at this point unaware of the existence of this resource. With that out of the way – some lectures!

i.

ii.

iii.

I don’t want to talk a lot about the stuff covered here, but I probably should mention that I’m pretty sure I read an article not long ago showing that biennial eye screenings are more cost-effective than annual screenings, and that expected outcomes in the two cases are pretty similar. I’m too lazy to look up the article though, this is just to say that if you’re a diabetic getting your eyes screened regularly, you probably shouldn’t lose sleep about the fact that they only look at your eyes every second year.

iv.

I think I may have mentioned this before, but in my childhood I caught myself wondering if our cat could actually tell the difference between me and some other person – that question related to the bigger question of how the cat perceived the world; if I looked different enough for it to tell that I wasn’t somebody else. Well, if I’d had a pet sheep instead there’d have been no doubt:

“So this is sheep, showing that they can discriminate between faces by pressing panels with their nose […] they’re extremely good at doing this, they can remember or discriminate up to about 50 different sheep faces … it’s probably more than that, this is as far as we went – and at least 10 different human faces, and they can remember them for several years.” (from the video, roughly 40 minutes in)

August 10, 2013 Posted by | diabetes, Lectures, mathematics, medicine, science | Leave a comment

The Ancestor’s Tale (II)

I finished the book yesterday, after having put it away for almost a month. According to a count I did after finishing the book, this was the 40th book I’ve completed this year so far, meaning that I’ve read roughly five and a half books per month on average, or roughly one book per five and a half days (such an average is deceiving though, as the amount of book reading varies widely throughout the year; more than half the books I’ve read this year I’ve read during the summer, i.e. since the beginning of June…). Let’s just say that getting to 50 (or 52?) before the end of the year should not be an impossible task at this point – I didn’t realize I was that far already.

Back to the book – below is my goodreads review of the Dawkins book:

“Parts of this book is pure awesome, and the best parts are really among the greatest things I’ve read on the subject.

But other parts are not quite so great. The treatment is not as systematic as I’d have liked. At one point an (in my opinion) off-topic political rant in the middle of a book about the evolutionary past of our species made me so angry I simply put the book away for almost a month. I’d pretty much decided not to finish it at that point.

I eventually did pick it up again though, and I’m glad I did. But some parts are much better than others, and it’s a damn shame the variation in the quality of the material is as high as it is.”

I gave it 4 stars, but it was difficult to pick a rating. I really liked the last 100-200 pages. Incidentally I pointed out in my first post that “he talks about different speciation methods/mechanisms throughout the pages, but he doesn’t mention what they are called” – and I should probably add here that he does add the names later on, though the last half of that original comment still applies (“his coverage is non-systematic and spread out over many pages”). I think if you’re the kind of curious mind who’d enjoy reading a book about the history of life on Earth, you have to read this. I think it could have been a bit better, and that’s basically why I didn’t end up with a five star rating – but this account is still probably about as good as it’s going to get, so I think if you’re limiting yourself to one book on the subject, this is probably the book to read. Even if it isn’t, I’m sure you could do a lot worse.

Below I’ve added some quotes from the last few hundred pages; I’ve tried to quote from ‘the good stuff’ only. The book has 600+ pages, so naturally a lot of good stuff didn’t make the cut, and in fact much of the best stuff I decided not to include here because it was too hard to quote out of context, because ‘too much stuff’ had to be included in each quote in order to make sense of it for someone who’d not read the rest of the book – indeed in a few cases basically the rest of the book had been building up to it (the last quote included in the post below is sort of like this, but it can stand on its own as well):

“A mutant animal has a certain probability of being better off as a consequence of its new mutation. ‘Better off’ means better compared to the premutated parental type. […] the smaller the mutation, the more likely it is to be an improvement. […] The essential point, as I have put it before, is that there are many more ways of being dead than of being alive. […] In the multidimensional landscape of all possible animals, living creatures are islands of viability separated from other islands by gigantic oceans of grotesque deformity. Starting from any one island, you can evolve away from it one step at the time, here inching out a leg, there shaving the tip of a horn, or darkening of a feather. Evolution is a trajectory through multidimensional space, in which every step of the way has to represent a body capable of surviving and reproducing as well as the parental type […] Almost inevitably, a megamutation […] will land in the middle of the ocean of inviability …” […]

“The key to efficient digestion is to expose a large area of absorptive surface to the food. We achieve that by chewing the food into small pieces and passing the fragments through a long coiled gut whose already large area is compounded by a forest of tiny projections, or villi, covering its lining. Each villus in turn has a brush border of hair-like micro-villi, so the total absorptive area of an adult human intestine is millions of square centimeters. A fungus such as the well-named Phallus […] spreads its mycelium over a similar area of soil, secreting digestive enzymes and digesting the soil material where it lies. The fungus doesn’t walk about devouring food and digesting it inside its body as a pig or a rat would. Instead it spreads its ‘intestines’, in the form of thread-like mycelia, right through the food and digests it on the spot. From time to time hyphae come together to form a single solid structure with recognisable form: a mushroom (or toadstool, or bracket). This structure manufactures spores that float high and far on the wind, spreading its genes for making new mycelium and, eventually, new mushrooms.” […]

“By far the largest single organisms that ever lived are plants, and an impressive percentage of the world’s biomass is locked up in plants. This doesn’t just happen to be so. Some such high proportion follows necessarily from the fact that almost* all biomass comes ultimately from the sun via photosynthesis, most of it in green plants, and the transaction at every link of the food chain is only about 10 per cent efficient. The surface of the land is green because of plants, and the surface of the sea would be green too if its floating carpet of photosynthesisers were macroscopic plants instead of microorganisms too small to reflect noticeable quantities of green light. It is as though plants are going out of their way to cover every square centimetre with green, leaving none uncovered. And that is pretty much what they are doing […] From a plant’s point of view, a square centimetre of the Earth’s surface that is anything but green amounts to a negligently wasted opportunity to sweep up photons.” […]

“The really astonishing thing about Kleiber’s Law is that it holds good from the smallest bacterium to the largest whale. That’s about 20 orders of magnitude. You need to multiply by ten 20 times – or add 20 noughts – in order to get from the smallest bacterium to the largest mammal, and Kleiber’s Law holds right across the board. […]
A very small organism has such a large surface area compared to its volume that it can get all the oxygen it needs through its body wall. […] But a large organism has a transport problem because most of its cells are far away from the supplies they need. They need to pipe stuff from place to place. […] if you double the number of cells that need to be supplied, the network volume more than doubles because more pipes are needed to plumb the network into the main system, pipes which themselves occupy space. […] whether you are a mouse or a whale, the most efficient transport system – the one that wastes the least energy in moving stuff around – is one that takes up a fixed percentage of your body. That’s how the mathematics works out […] For example, mammals, whether mice, humans, or whales, have a volume of blood (i.e. the size of the transport system) which occupies between six and seven per cent of their body.
Taking these two points together, it means that if we wish to double the number of cells to be supplied, but still keep the most efficient transport system, we need a more sparsely distributed supply network. And a more sparse network means that less stuff is supplied per cell, meaning that the metabolic rate must go down.” […]

“A nucleus is huge compared to an electron but tiny compared to an electron’s orbit. Your hand, consisting mostly of empty space, meets hard resistance when it strikes a block of iron, also consisting mostly of empty space, because forces associated with the atoms in the two solids interact in such a way as to prevent them passing through each other. Consequently iron and stone seem solid to us because our brains most usefully serve us by constructing an illusion of solidity.” […]

“one of the most momentous events in the history of life was the formation of the eukaryotic cell. Eukaryotic cells are the large and complex cells, with walled nuclei and mitochondria, that make up the bodies of all animals, plants, and indeed […] all living creatures except the true bacteria and the archaea, which used to be called bacteria.” […] […a big exception, it turns out:] “bacteria and archaea are biochemically more versatile than the rest of the living kingdoms put together. Animals and plants perform a fraction of the biochemical mix of tricks available to bacteria. […] At least as a chemist would see it, if you wiped out all life except bacteria, you’d still be left with the greater part of life’s range. […] For the great majority of its career on this planet life has been nothing but prokaryotic life. We animals are a recent afterthought.” […]

“Depriving somebody of oxygen is a swift way to kill them. Yet our own cells, unaided, wouldn’t know what to do with oxygen. It is only mitochondria, and their bacterial cousins, that do.
As with chloroplasts, molecular comparison tells us the particular group of bacteria from which mitochondria are drawn. Mitochondria sprang from the socalled alpha-proteo bacteria and they are therefore related to the rickettsias that cause typhus and other nasty diseases. Mitochondria themselves have lost much of their original genome, and have become completely adapted to life inside the eukaryotic cells. But, like chloroplasts, they still reproduce autonomously by division, making populations within each eukaryotic cell.”

Of course he couldn’t help himself in the end from adding the remarks below in his conclusion (with which I of course agree):

“If it’s amazement you want, the real world has it all. […] although this book […629 pages, US…] has been written from a human point of view, another book could have been written in parallel for any of 10 million starting pilgrims. […] My objection to supernatural beliefs is precisely that they miserably fail to do justice to the sublime grandeur of the real world. They represent a narrowing-down from reality, an impoverishment of what the real world has to offer.”

August 9, 2013 Posted by | biology, books, evolution | Leave a comment

Wikipedia articles of interest

i. Battle of Passchendaele.

624px-Chateau_Wood_Ypres_1917

“The Battle of Passchendaele (or Third Battle of Ypres or “Passchendaele”) [Note 2] was a campaign of the First World War, fought by the British and their allies against the German empire. The battle took place on the Western Front, between June and November 1917, for control of the ridges south and east of the Belgian city of Ypres in West Flanders, as part of a strategy decided by the Allies at conferences in November 1916 and May 1917.[3] Passchendaele lay on the last ridge east of Ypres, five miles from a railway junction at Rouselare, which was a vital part of the supply system of the German Fourth Army.[4][Note 3] The next stage of the Allied strategy was an advance to Torhout – Couckelaere, to close the German-controlled railway running through Roeselare and Torhout, which did not take place until 1918. Further operations and a British supporting attack along the Belgian coast from Nieuwpoort, combined with an amphibious landing, were to have reached Bruges and then the Dutch frontier.[6] The resistance of the German Fourth Army, unusually wet weather, the onset of winter and the diversion of British and French resources to Italy, following the Austro-German victory at the Battle of Caporetto (24 October – 19 November) allowed the Germans to avoid a general withdrawal, which had seemed inevitable to them in October.[7] The campaign ended in November when the Canadian Corps captured Passchendaele.[8] In 1918 the Battle of the Lys[9] and the Fifth Battle of Ypres,[10] were fought before the Allies occupied the Belgian coast and reached the Dutch frontier.[11]

A campaign in Flanders was controversial in 1917 and has remained so. […] Matters of dispute by the participants and writers and historians since the war have included: the wisdom of pursuing an offensive strategy in the wake of the failed Nivelle Offensive, rather than waiting for the arrival of the American armies in France; the choice of Flanders over areas further south or the Italian front; the climate and weather in Flanders; Haig’s selection of General Hubert Gough and the Fifth Army to conduct the offensive; debates over the nature of the opening attack between advocates of shallow and deeper objectives; the passage of time between the Battle of Messines and the opening attack of the Battles of Ypres; the extent to which the internal troubles of the French armies motivated British persistence in the offensive; the effect of mud on operations; the decision to continue the offensive in October once the weather had broken, and the human cost of the campaign on the soldiers of the German[15] and British armies.[16] […]

Various casualty figures have been published, sometimes with much acrimony, although the highest estimates for British and German casualties appear to be discredited.[152] In the Official History, (1948) Brigadier-General James E. Edmonds put British wounded and killed at 244,897 and claimed that equivalent German figures were not available, estimating German losses at 400,000. Edmonds considered that 30% needed to be added to German statistcs to make them comparable with British casualty criteria.[153][Note 9] In 2007 Jack Sheldon rejected Edmonds’s calculations, suggesting that although German casualties 1 June – 10 November were 217,194, a figure available in Volume III of the Sanitätsbericht (1934, Medical Report Concerning the German Army 1914 – 1918) Edmonds may not have included them as they did not fit his case. Sheldon noted 182,396 slightly wounded and sick soldiers not struck off unit strength which if included would make German losses 399,590.[163] As yet the British claim to have captured 24,065 prisoners has not been disputed.[164]

ii. n-body problem.

“The n-body problem is the problem of predicting the motion of a group of celestial objects that interact with each other gravitationally. Solving this problem has been motivated by the need to understand the motion of the Sun, planets and the visible stars. Its first complete mathematical formulation appeared in Isaac Newton‘s Principia […]

The 2-body problem has been completely solved. For n = 3, solutions exist for special cases. A general solution in terms of first integrals is known to be impossible. An exact theoretical solution for arbitrary n can be given in terms of Taylor series, but in practice such an infinite series must be truncated, giving an approximate solution. In addition, many solutions by numerical integration exist, but these too are approximate solutions.”

Given the nature of the material covered, this article is of course somewhat technical.

iii. Ming Dynasty (featured).

“The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China for 276 years (1368–1644) following the collapse of the Mongol-led Yuan Dynasty. The Ming, described by some as “one of the greatest eras of orderly government and social stability in human history”,[5] was the last dynasty in China ruled by ethnic Han Chinese. Although the primary capital of Beijing fell in 1644 to a rebellion led by Li Zicheng (who established the Shun Dynasty, soon replaced by the Manchu-led Qing Dynasty), regimes loyal to the Ming throne – collectively called the Southern Ming – survived until 1662.

The Hongwu Emperor (ruled 1368–98) attempted to create a society of self-sufficient rural communities ordered in a rigid, immobile system that would guarantee and support a permanent class of soldiers for his dynasty:[6] the empire’s standing army exceeded one million troops and the navy‘s dockyards in Nanjing were the largest in the world.[7] He also took great care breaking the power of the court eunuchs[8] and unrelated magnates, enfeoffing his many sons throughout China and attempting to guide these princes through published dynastic instructions. This failed spectacularly when his teen-aged successor attempted to curtail his uncles’ power, prompting the uprising that placed the Prince of Yan upon the throne as the Yongle Emperor in 1402. The Yongle Emperor established Yan as a secondary capital and renamed it Beijing, constructed the Forbidden City, and restored the Grand Canal and the primacy of the imperial examinations in official appointments. He rewarded his eunuch supporters and employed them as a counterweight against the Confucian scholar-bureaucrats. One, Zheng He, led seven enormous voyages of exploration into the Indian Ocean as far as Arabia and the coast of Africa.

The rise of new emperors and new factions diminished such extravagances; the capture of the Zhengtong Emperor during the 1449 Tumu Crisis ended them completely. The imperial navy was allowed to fall into disrepair while forced labor constructed the Liaodong palisade and connected and fortified the Great Wall of China into its modern form. Wide-ranging censuses of the entire empire were conducted decennially, but the desire to avoid labor and taxes and the difficulty of storing and reviewing the enormous archives at Nanjing hampered accurate figures.[6] Estimates for the late-Ming population vary from 160 to 200 million,[9] but necessary revenues were squeezed out of smaller and smaller numbers of farmers as more disappeared from the official records or “donated” their lands to tax-exempt eunuchs or temples.[6] Haijin laws intended to protect the coasts from “Japanese” pirates instead turned many into smugglers and pirates themselves.” […]

Ming-Empire2

“The Mongol-led Yuan Dynasty (1271–1368) ruled before the establishment of the Ming Dynasty. Alongside institutionalized ethnic discrimination against Han Chinese that stirred resentment and rebellion, other explanations for the Yuan’s demise included overtaxing areas hard-hit by inflation, and massive flooding of the Yellow River as a result of the abandonment of irrigation projects.[10] Consequently, agriculture and the economy were in shambles and rebellion broke out among the hundreds of thousands of peasants called upon to work on repairing the dykes of the Yellow River.[10] […]

The Ming sporadically sent armed forays into Tibet during the 14th century, which the Tibetans successfully resisted.[34][35] Several scholars point out that unlike preceding Mongols, the Ming Dynasty did not garrison permanent troops in Tibet.[36][37] The Wanli Emperor (r. 1572–1620) attempted to reestablish Sino-Tibetan relations in the wake of a Mongol-Tibetan alliance initiated in 1578, an alliance which affected the foreign policy of the subsequent Manchu Qing Dynasty (1644–1912) in their support for the Dalai Lama of the Yellow Hat sect.[26][38][39][40] By the late 16th century, the Mongols proved to be successful armed protectors of the Yellow Hat Dalai Lama after their increasing presence in the Amdo region, culminating in Güshi Khan‘s (1582–1655) conquest of Tibet in 1642.[26][41][42] […]

The imperial household was staffed almost entirely by eunuchs and ladies with their own bureaus.[90] […] as eunuch power at court increased, so did their administrative offices, with eventual twelve directorates, four offices, and eight bureaus.[90] The dynasty had a vast imperial household, staffed with thousands of eunuchs, who were headed by the Directorate of Palace Attendants. The eunuchs were divided into different directorates in charge of staff surveillance, ceremonial rites, food, utensils, documents, stables, seals, apparel, and so on.[91] The offices were in charge of providing fuel, music, paper, and baths.[91] The bureaus were in charge of weapons, silverwork, laundering, headgear, bronzework, textile manufacture, wineries, and gardens.[91] At times, the most influential eunuch in the Directorate of Ceremonial acted as a de facto dictator over the state.[92] […] Eunuchs during the Ming Dynasty gained unprecedented power over state affairs. […]

After the reign of Hongwu—who from 1373 to 84 staffed his bureaus with officials gathered through recommendations only—the scholar-officials who populated the many ranks of bureaucracy were recruited through a rigorous examination system that was first established by the Sui Dynasty (581–618).[96][97][98] Theoretically the system of exams allowed anyone to join the ranks of imperial officials (although frowned upon for merchants to join); in reality the time and funding needed to support the study in preparation for the exam generally limited participants to those already coming from the landholding class. However, the government did exact provincial quotas while drafting officials.[99] This was an effort to curb monopolization of power by landholding gentry who came from the most prosperous regions, where education was the most advanced.[100] The expansion of the printing industry since Song times enhanced the spread of knowledge and number of potential exam candidates throughout the provinces.[101] For young schoolchildren there were printed multiplication tables and primers for elementary vocabulary; for adult examination candidates there were mass-produced, inexpensive volumes of Confucian classics and successful examination answers.[102] […] The exams increased in difficulty as the student progressed from the local level, and appropriate titles were accordingly awarded successful applicants. Officials were classified in nine hierarchic grades, each grade divided into two degrees, with ranging salaries (nominally paid in piculs of rice) according to their rank. […]

Compared to the flourishing of science and technology in the Song Dynasty, the Ming Dynasty perhaps saw fewer advancements in science and technology compared to the pace of discovery in the Western world. In fact, key advances in Chinese science in the late Ming were spurred by contact with Europe. […]

Sinologist historians still debate the actual population figures for each era in the Ming Dynasty. The historian Timothy Brook notes that the Ming government census figures are dubious since fiscal obligations prompted many families to underreport the number of people in their households and many county officials to underreport the number of households in their jurisdiction.[193] Children were often underreported, especially female children, as shown by skewed population statistics throughout the Ming.[194] Even adult women were underreported;[195] for example, the Daming Prefecture in North Zhili reported a population of 378 167 males and 226 982 females in 1502.[196] The government attempted to revise the census figures using estimates of the expected average number of people in each household, but this did not solve the widespread problem of tax registration.[197] Some part of the gender imbalance may be attributed to the practice of female infanticide. The practice is well documented in China, going back over two thousand years, and it was described as “rampant” and “practiced by almost every family” by contemporary authors.[198] However, the dramatically skewed sex ratios, which many counties reported exceeding 2:1 by 1586, can’t likely be explained by infanticide alone.[195]

iv. Lung cancer (featured).

Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue or other parts of the body. Most cancers that start in lung, known as primary lung cancers, are carcinomas that derive from epithelial cells. The main types of lung cancer are small-cell lung carcinoma (SCLC), also called oat cell cancer, and non-small-cell lung carcinoma (NSCLC). The most common symptoms are coughing (including coughing up blood), weight loss and shortness of breath.[1]

The most common cause of lung cancer is long-term exposure to tobacco smoke,[2] which causes 80–90% of lung cancers.[1] Nonsmokers account for 10–15% of lung cancer cases,[3] and these cases are often attributed to a combination of genetic factors,[4] radon gas,[4] asbestos,[5] and air pollution[4] including second-hand smoke.[6][7] Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy[8] which is usually performed by bronchoscopy or CT-guidance. Treatment and long-term outcomes depend on the type of cancer, the stage (degree of spread), and the person’s overall health, measured by performance status. […]

Overall, 15% of people in the United States diagnosed with lung cancer survive five years after the diagnosis.[10] Worldwide, lung cancer is the most common cause of cancer-related death in men and women …”

v. Fick’s laws of diffusion.

vi. Hox genes.

August 7, 2013 Posted by | genetics, history, medicine, Physics, wikipedia | Leave a comment

The ABC murders

Read the book today. I decided to give this one a three star rating (average goodreads rating is 3.88). I can’t really talk about my motivations for doing so without providing spoilers.

A good thing about the book is that she once or twice moves very close to the fourth wall – I love when authors play around with that stuff. I decided to add a few illustrative quotes from the book (which I highly doubt will spoil the book for you) below:

[Poirot is bored, and so he and Hastings start talking about what a ‘creamy crime’ (the ideal mystery) for them to investigate would be like:]

“”Robbery? Forgery? No, I think not. Rather too vegetarian. It must be murder […] “Who shall the victim be — man or woman? Man, I think. Some bigwig. American millionaire. Prime Minister. Newspaper proprietor. Scene of the crime — well, what’s wrong with the good old library? Nothing like it for atmosphere. As for the weapon — well, it might be a curiously twisted dagger — or some blunt instrument — a carved stone idol—”
Poirot sighed.
“Or, of course,” I said, “there’s poison—but that’s always so technical. Or a revolver shot echoing in the night. Then there must be a beautiful girl or two—”
“With auburn hair,” murmured my friend.
“Your same old joke. One of the beautiful girls, of course, must be unjustly suspected — and there’s some misunderstanding between her and a young man. And then, of course, there must be  some other suspects — an older woman — dark, dangerous type — and some friend or rival of the dead man’s — and a quiet secretary  — dark horse — and a hearty man with a bluff manner — and a couple of discharged servants or gamekeepers or somethings — and a damn fool of a detective rather like Japp — and well — that’s about all.”
“That’s your idea of the cream, eh?”
“I gather you don’t agree?”
Poirot looked at me sadly.
“You have made there a very pretty résumé of nearly all detective stories that have ever been written.””

“”You have the melodramatic soul, Hastings. You would like, not one murder, but a series of murders.”
“I admit,” I said, “that a second murder in a book often cheers things up. If the murder happens in the first chapter, and you have to wait to follow up everybody’s alibi until the last page but one — well, it does get a bit tedious.”

“”Your aunt never thought of freeing herself by legal means from this persecution?”
“Well, you see, he was her husband, sir, you couldn’t get away from that.”
The girl spoke simply but with finality.
“Tell me, Mary, he threatened her, did he not?”
“Oh, yes, sir, it was awful the things he used to say. That he’d cut her throat, and such like.”” (but then again he was her husband, so… Aargh!)

[Setting: They’ve almost only just started out with the case, there were zero witnesses to the crime and pretty much no clues. Poirot and Hastings are talking to each other…]
“”The crime,” said Poirot, “was committed by a man of medium height with red hair and a cast in the left eye. He limps slightly on the right foot and has a mole just below the shoulder blade.”
“Poirot?” I cried.
For the moment I was completely taken in. Then the twinkle in my friend’s eye undeceived me.
“Poirot!” I said again, this time in reproach.
Mon ami, what will you? You fix upon me a look of dog-like devotion and demand of me a pronouncement à la Sherlock Holmes! Now for the thruth – I do not know what the murderer looks like, nor where he lives, nor how to set hands upon him.

August 5, 2013 Posted by | books | 2 Comments

Gender, Physical Activity, and Aging (2)

I’ve finished the book. I gave it four stars. There’s a lot of research covered here, lots of ground covered, and most of it is well written. When findings are conflicting we are told so, and the reasons for discrepancies across studies are often investigated in some detail. Conclusions drawn are often of a tentative nature, and the uncertainties involved are often emphasized. Given the amount of material covered, detailed coverage of specific studies and their limitations is somewhat limited, but stuff like differences in study design across studies and consequences of these are occasionally emphasized; the lack of longitudinal studies in specific areas of research covered are for example a few times highlighted as a potential problem regarding which causal inferences to draw from the research. Sometimes the controls included in a specific study are mentioned, sometimes they’re not, and that bothered me a little a few times as it was for example unclear in some cases whether a specific study had controlled for initial health status or not; the inclusion of this variable might not deal completely with the endogeneity problem (exercise affects health status, but health status also affects exercise ability – or at the very least perceived exercise ability), but without including it in some specific cases you’re quite likely to get into trouble, and it seems very probably that some older studies have overlooked this problem. In the book the results of quite a few RCTs are covered, which is nice – but there are also a lot of cross-sectional studies, epidemiological studies of various kinds, survey-based stuff… Natural experiments are almost (? can’t remember now if the proper word is ‘completely’…) absent in this work, but then again I guess this book was written before IV estimation really took off, and besides such methods would be most useful in areas which although related to the areas covered in the book are still sufficiently different in scope for it to (arguably) make sense not to include that kind of stuff in the book.

In general the stuff’s not easy to read if you don’t know a lot of stuff about biology, physiology and related fields, and I felt more than a few times that I was in over my head (though some chapters were a lot easier than others; because of my knowledge of diabetes and the physiological consequences of adiposity chapter 10 was an easy read) – but stuff like study methodology should not cause you problems as most of the -designs applied are quite uncomplicated. The stuff included about health impacts of health interventions (e.g. exercise) deals mainly with ‘idealized’ high-compliance settings; they do talk a bit about the adherence-/compliance problems which are observed when doing intervention studies, but more focus on this aspect might have been a good idea – at least I think the book sells the idea that exercise is good for the individual much better than it does the idea that large-scale policy interventions undertaken in order to improve health that way might be a good idea. I believe quite a bit of work has been done in that area since then, so you can find out about that stuff elsewhere.

I haven’t ‘punished’ the authors for not defining all terms applied in the work and for including stuff I was supposed to know but didn’t – it’s not their fault I’m an ignorant fool. But you should have in mind when interpreting my rating that a person like me is borderline too ignorant about stuff like immunology, microbiology, and cardiology to read and understand all the stuff in the book, despite having, among other things, read textbooks dealing with all three areas before. I got a lot of stuff out of this book, but I’d have gotten more out of it if I’d have known more about some of the things they cover.

I have included some observations from the book below. I’ve mostly stayed clear of the technical stuff:

“It has been suggested that declines in functional capacity with age reflect age-related reductions in physical activity. Inactivity has been estimated to account for 50% of the age-related loss in function. […]

The ability to move with purpose and to remain independent with increasing age depends to a large degree on retaining an adequate functional capacity in the neuromuscular system. This system, which governs the generation and control of muscle force, typically undergoes a substantial decline in functional capacity with age […] Beginning at approximately 30 years of age, human muscular strength declines at a rate of 10 to 15% per decade1 […] Because the activities of daily living usually do not require maximal muscular efforts, the gradual loss of strength for most individuals does not become functionally significant until after 55 to 60 years of age. […]

Evidence is accumulating that progressive resistance exercise is an efficacious, nonpharmacological treatment for age-related losses in muscle mass, quality, and function. The benefits of regular physical activity throughout the life span have been a major focus of exercise physiologists for many decades. […] Taken together, these results suggest that, if sustained over a lifetime, regular physical activity has a significant protective effect on muscle strength, function, and oxidative capacity. Benefits appear to relate not only to function, but also to longevity.9,10 […]

Evidence from both animal and human models suggests that there are age-related differences in the susceptibility of skeletal muscle to exercise-induced damage and ability for post-damage repair. One such difference is in the amount of work required to induce muscle damage. […] Human studies have […] tended to demonstrate a greater degree of exercise-induced muscle damage in elderly than in younger adults. […] Most animal and human studies agree that recovery from acute exercise-induced muscle damage is impaired in older subjects. […]

evidence is mounting that estrogen may be a key hormone for maintaining muscle strength in women.96 […] although gender differences in tissue antioxidant potential, partially due to estrogen, may exist, their importance in influencing exercise-induced peroxidative muscle damage is still undefined. […] whether females are afforded greater protection from postexercise muscle inflammatory damage and/or are delayed in muscle healing rates as a consequence of their higher estrogen levels is not yet firmly established. […]

The elderly appear to be more susceptible to exercise-induced muscle damage than younger adults. In addition, following such damage, there seems to be a relative impairment in muscle repair and adaptation in the sedentary elderly. Nevertheless, evidence suggests that the ability of older muscle to adapt to a resistance training program remains robust, and the physiological mechanisms associated with muscle repair and hypertrophy are still able to function even in older adults. […] regular resistance exercise may be one of the best intrinsic methods of protecting muscles from exercise-induced muscle damage and helping to normalize the rate and quality of muscle repair processes and adaptation to muscular activity in older individuals. […]

Over half of the older population is afflicted by arthritis, and approximately one-third of postmenopausal women will experience an osteoporotic fracture in their lifetime.1 […] distinguishing between disease processes and disease consequences of arthritis and normal aging is complex. […] More than 80% of people over the age of 75 years have clinical osteoarthritis and more than 80% of people over the age of 50 have radiologic evidence of the condition. Before the age of 50 years, the prevalence of osteoarthritis in most joints is higher in men than in women. […] The prevalence of rheumatoid arthritis increases with age and is found in about 10% of adults older than 65 years of age. […] The association between obesity and osteoarthritis has been evident for many years, but whether obesity was a cause or a consequence of the disease was unclear. It now appears that obesity not only predates osteoarthritis, but also increases the rate of disease progression, especially in women and in those with osteoarthritis of the knee.26,27 […] Occupational or recreational activities associated with excessive, repetitive, or high-impact joint loads are risk factors for osteoarthritis. In contrast, moderate physical activity such as running decreases the risk for osteoarthritis, at least in men.28 […] General exercise and physical activities are not harmful to the arthritic process, as was once thought. […] Despite many interstudy differences of methodology, there is consistent support for the notion that exercise and physical activity can and should play a role in both prevention and rehabilitation. […]

The one fairly robust finding across studies of exercise adherence is past exercise behavior. […] The fact that current exercise behavior appears to be best predicted by past exercise behavior is not surprising, but it is disconcerting, given that those individuals who most need to exercise are also those who are least likely to exercise. […]

Based upon […] systematic reviews of randomized investigations, the effect of exercise on bone mass appears to be a gain of approximately 1% per year, regardless of menopausal status. Data comparing male and female subjects are limited […]

Aging, per se, appears to have only a small effect on glucose intolerance and insulin resistance. The majority of insulin resistance that develops in older women and men is explained by increased adiposity, particularly in the abdominal region. […] life style appears to be a much stronger determinant of insulin resistance than aging per se. […]

Overall, exercise training in later life reduces the magnitude of catecholamine and pituitary hormone responses to a given bout of exercise, and increases the resistance to physical stress. Given that stress hormones are in general immunosuppressive, appropriate exercise training may be beneficial for the aging immune system, raising the threshold level of immunosuppressive (i.e., strenuous and/or prolonged) physical exercise. […] Strenuous exercise increases concentrations of various proinflammatory and anti-inflammatory cytokines, naturally occurring cytokine inhibitors, and chemokines.43 Given that aging is associated with increased inflammatory activity, strenuous exercise may induce the cytokine cascade more markedly in aging adults than in young peers. […] The results seem to imply that older adults should adopt a more cautious approach to strenuous exercise. […]

Human immune function undergoes adverse changes with aging. The T cells, which have a central role in cellular immunity, show the largest age-related differences in distribution and function. The underlying causes include thymus involution and continuous attrition caused by chronic antigenic overload. Immune function is apparently sexually dimorphic; women have more vigorous immunologic activity than do men, thus reducing their risks of infection. However, the same mechanisms make women more susceptible to various autoimmune diseases. The sexual dimorphism in immune function may become less apparent with aging, although it persists into later life […]

In Canada, by the age of 65 years, 37% of women and 31% of men have noted some limitations in their physical activity.28 As early as 55 years of age, 2% of men and 10% of women are unable to carry their groceries, and in those over the age of 80 years, the prevalence of this particular handicap rises to 20% of men and 30% of women.81 […] When interpreting functional changes, it is often difficult to disentangle what is a consequence of normal aging from the effects of disuse and chronic disease. One U.S. study estimated that as much as half of age-related decline in functional capacity was self-imposed, due to an accumulation of body fat and a failure to take adequate physical activity.32 […] in Denmark, Avelund et al.5 noted a substantial inverse relationship between levels of habitual physical activity and the loss of functional capacity. […]

Although an age-related loss of function can in itself cause disability, chronic disease is the usual source of impairment. […] A major part of the age-related loss of functional capacity, with the associated social and economic costs of prolonged disability, is due to adoption of an inappropriate lifestyle. […] The apparent prevalence of various disease conditions varies according to the diagnostic criteria applied. For example, aging is inevitably associated with a progressive increase in blood pressure, but when a certain arbitrary level of pressure is surpassed, hypertension is diagnosed […] Similarly, when the age-related decrease in bone mineral content reaches an arbitrary figure, clinical osteoporosis is diagnosed. […]

Many elderly people have multiple disorders, and it is then difficult to assess the contribution of specific conditions to the reported level of disability. In young and middle old age, the main causes of disability are chronic disease and a restriction of mobility, but in the oldest old mental deterioration and a loss of the special senses become important sources of impairment.62 […]

the main social costs associated with aging are incurred in the final year of life, as heroic attempts are made to prolong the survival of sedentary and severely disabled individuals.9,17 Regular physical activity decreases the risk of chronic disease and thus the scope for heroic treatment; it increases healthy life expectancy.17 […] there is little evidence that regular physical activity prolongs survival into advanced old age. What it does is to avert premature death, at a time when an individual is contributing to society rather than drawing upon its resources. The survival curves for active and sedentary individuals converge around the age of 80 years […]

The muscle force and aerobic power required to undertake many of the tasks important to the independence of an elderly person (for example, rising from a chair or climbing a flight of stairs) are almost directly proportional to an individual’s body mass. Thus, a 10% reduction in body mass will effectively increase muscle strength and maximal aerobic power by some 10%, equivalent to a 10-year reversal of the effects of aging.”

August 4, 2013 Posted by | books, data, demographics, health, medicine | 2 Comments