Econstudentlog

Stuff we don’t know much about (/yet?) (…/a continuing series?)

“Water is essential for maintaining life on Earth but can also serve as a media for many pathogenic organisms, causing a high disease burden globally. However, how the global distribution of water-associated infectious pathogens/diseases looks like and how such distribution is related to possible social and environmental factors remain largely unknown. In this study, we compiled a database on distribution, biology, and epidemiology of water-associated infectious diseases and collected data on population density, annual accumulated temperature, surface water areas, average annual precipitation, and per capita GDP at the global scale. From the database we extracted reported outbreak events from 1991 to 2008 and developed models to explore the association between the distribution of these outbreaks and social and environmental factors. […]

Worldwide, water-associated infectious diseases are a major cause of morbidity and mortality [11], [12], [13]. A conservative estimate indicated that 4.0% of global deaths and 5.7% of the global disease burden (in DALYs) were attributable to a small subset of water, sanitation, and hygiene (WSH) related infectious diseases including diarrheal diseases, schistosomiasis, trachoma, ascariasis, trichuriasis, and hookworm infections [11], [14], [15]. Although unknown, the actual disease burden attributable to water-associated pathogens is expected to be much higher. A total of 1415 species of microorganisms have been reported to be pathogenic, among which approximately 348 are water-associated, causing 115 infectious diseases [5].Yet, their distribution and associated factors at the global scale remain largely unexplored. […]

The population density was shown to be a significant risk factor for reported outbreaks of all categories of water-associated infectious diseases and the probability of outbreak occurrence increased with the population density. The accumulated temperature was a significant risk factor for water-related diseases only. The analysis suggested that occurrence of water-washed diseases had significantly inverse relationship with surface water areas. Such inverse relationship was also observed between the average annual rainfall and water-borne diseases (including water-carried) and water-related diseases.”

From Global Distribution of Outbreaks of Water-Associated Infectious Diseases by Yang, LeJeune et al.

February 27, 2012 Posted by | Epidemiology, Infectious disease, Medicine, Studies | Leave a comment

Wikipedia articles of interest

i. Control of fire by early humans. I read about this stuff in The Human Past as well, but like in so many other cases wikipedia actually has a lot of stuff if you care to look for it. Wikipedia’s treatment of this subject does not seem to be out of line with the evidence presented in THP; generally it seems to be the case that people knew how to make fire around 125-130.000 years ago, but it is not clear when/where this ability first evolved (THP sums it up like this: “Spreads of burned sediment, ash, and charcoal that almost certainly signal fireplaces are conspicuous in many sites occupied by the European Neanderthals and their near-modern African contemporaries after 130,000 years ago, and it is generally assumed that people everywhere after 130,000 years ago could make fire when they needed it. The question is when this ability evolved, or perhaps more precisely, whether a stage of full control followed on one when fire use was sporadic and opportunistic. This issue is difficult to address since sites older than 130,000 years ago are relatively rare and they are mostly open-air localities.” […] caves are far more likely to preserve fossil fireplaces.” p.117. The problem is that at an open-air site, it’s much more difficult to tell if the fire was made by humans or natural processes.)

ii. Danish phonology. Some interesting aspects:

“Unlike the neighboring Mainland Scandinavian languages Swedish and Norwegian, the prosody of Danish does not have phonemic pitch. Stress is phonemic and distinguishes words like billigst [ˈb̥ilisd̥] “cheapest” and bilist [b̥iˈlisd̥] “car driver”. The main rules for the position of the stress are:

1. Inherited words are normally stressed on the first syllable.
2. The prefixes be-, for-, ge-, u- are unstressed, e.g. for’stå “understand”, be’tale “pay”, u’mulig “impossible” (NB there is also a stressed for- in nouns corresponding to the verbal prefix fore-).
3. In many compound adjectives, especially those ending in -ig and -lig, the stress is replaced from the first to the second syllable, e.g. vidt’løftig “circumstantial”, sand’synlig “probable”.
4. Words of French origin are stressed on the last syllable (except /ə/), e.g. renæ’ssance, mil’jø.
5. Words of Greek and Latin origin are stressed according to the Latin accent rules, i.e. stress on the penultimate if it is long or else on the antepenultimate, e.g. Ari’stoteles, Ho’rats.
6. The learned suffixes -aner, -ansk, -ance, -a/ens, -a/ent, -ere, -i, -ik, -ion, -itet, -ør are stressed, e.g. finge’rere, situa’tion, poli’tik, århusi’aner. The preceding syllable is stressed before the learned suffixes -isk, -iker, -or, e.g. po’lemisk, po’litiker, radi’ator. The suffix -or is stressed in the plural: radia’torer (colloquial: radi’atorer).
7. Verbs lose their stress (and stød, if any) in certain positions:

With an object without a definite or indefinite article: e.g. ’Jens ’spiser et ’barn [ˈjɛns ˈsb̥iːˀsɐ ed̥ ˈb̥ɑːˀn] “Jens eats a child” ~ ’Jens spiser ’børn [ˈjɛns sb̥isɐ ˈb̥ɶɐˀn] “Jens eats children”.
In a fixed phrase with an adverb or an adverbial: ’Helle ’sov ’længe [ˈhɛlə ˈsʌʊˀ ˈlɛŋə] “Helle slept for a long time” ~ ’Helle sov ’længe [ˈhɛlə sʌʊ ˈlɛŋə] “Helle slept late”.
Before the direction adverbs af, hen, hjem, ind, indad, ned, nedad, op, opad, over, ud, udad, under (but not the location adverbs henne. inde, nede, oppe, ovre, ude): e.g. han ’går ’ude på ’gaden [hæn ˈɡɒːˀ ˈuːð̪̩ pʰɔ ˈɡ̊æːð̪̩n] “he walks on the street” ~ han går ’ud på ’gaden [hæn ɡɒ ˈuð̪ˀ pʰɔ ˈɡ̊æːð̪̩n] “he walks into the street”.

Stød

The original pitch tone has been replaced by an opposition between syllables with and without the stød. The stød is not a separate phoneme, but a suprasegmental feature that may accompany certain syllables; those with a long vowel or that end with a voiced consonant.

The stød is phonemic since many words are kept apart on the basis of the presence or absence of the stød alone, e.g. løber “runner” [ˈløːb̥ɐ] ≠ løber “runs” [ˈløːˀb̥ɐ / ˈløʊ̯ˀɐ], ånden “breathing” [ˈʌnn̩] ≠ ånden “the spirit” [ˈʌnˀn̩].

It is impossible to predict the presence or absence of the stød; it has to be learned. However there are some main rules:

1. Original monosyllabic words have stød. Words that ended in consonant + r, l, n in Old Danish have the stød even though an anaptyctic vowel was later developed. The postposed definite article, which has become an inseparable part of the word, does not influence the word.
2. All umlauting plurals in -er (ODan. -r) have the stød, e.g. hænder [ˈhɛnˀɐ] “hands”.
3. Most presents from strong verbs (ODan. -r) have the stød, e.g. finder [ˈfenˀɐ] “finds”. Many of the presents of verbs with a preterite in -te have the stød as well (but not the presents of verbs with a preterite in -ede).
4. Monosyllabic words that originally ended in a short vowel + a single n, r, l, v, ð, g do not have the stød. However, when the definite suffix is added, the stød “returns”, e.g. ven [ˈʋɛn] ~ vennen [ˈʋɛnˀn̩] “friend”.
5. Stød is frequently avoided in words with the combinations rp, rt, rk, rs, e.g. vers [ˈʋæɐ̯s] “verse”, kort [ˈkʰɒːd̥] “card, map”/”short”.
6. Most (non-derived) words in -el, -er have the stød. Most words in -en do not have the stød. Nomina agentis in -er do not have the stød.
7. All words with the unstressed prefixes be-, for-, ge- have the stød.
8. There is stød in most compounds that have a replacement of the stress from first to the second syllable.
9. There is frequently the stød in the second part of compound verbs.
10. Monosyllables regularly lose the stød when they are the first part of a compound: mål [ˈmɔːˀl] “target, goal” ~ målmand [ˈmɔːlˌmænˀ] “goalkeeper”. The vowel is sometimes shortened: tag [ˈtˢæːˀ] “roof” ~ tagterrasse [ˈtˢɑʊ̯tˢaˌʁɑsə] ”roof terrace”
11. Words of Greek or Latin origin have the stød on a stressed antepenultimate syllable or a stressed last syllable. A stressed penultimate syllable has the stød if the word ends in -er.”

The non-verbal aspects of human interaction increase the demands on the human brain to deal with complexity immensely in ways we don’t think about, but let’s not pretend that the verbal aspects are necessarily simple and easy to deal with. It’s very hard to remember how much you need to know and learn to master a human language unless you’re in the process of actively doing it.

iii. Borromean rings.

“In mathematics, the Borromean rings[1] consist of three topological circles which are linked and form a Brunnian link, i.e., removing any ring results in two unlinked rings.”

They are weird, that’s what they are. Here’s an image from the article:

iv. Terminal velocity. From the article:

“In fluid dynamics an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving.

A free-falling object achieves its terminal velocity when the downward force of gravity (FG) equals the upward force of drag (Fd). This causes the net force on the object to be zero, resulting in an acceleration of zero.[1]

As the object accelerates (usually downwards due to gravity), the drag force acting on the object increases, causing the acceleration to decrease. At a particular speed, the drag force produced will equal the object’s weight (mg). At this point the object ceases to accelerate altogether and continues falling at a constant speed called terminal velocity (also called settling velocity). An object moving downward with greater than terminal velocity (for example because it was thrown downwards or it fell from a thinner part of the atmosphere or it changed shape) will slow down until it reaches terminal velocity. […]

The reason an object reaches a terminal velocity is that the drag force resisting motion is approximately proportional to the square of its speed. At low speeds, the drag is much less than the gravitational force and so the object accelerates. As it accelerates, the drag increases, until it equals the weight. Drag also depends on the projected area. This is why objects with a large projected area relative to mass, such as parachutes, have a lower terminal velocity than objects with a small projected area relative to mass, such as bullets.”

v. Gyromitrin.

vi. Caspase.

“Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis (programmed cell death), necrosis, and inflammation.[2]

Caspases are essential in cells for apoptosis, or programmed cell death, in development and most other stages of adult life, and have been termed “executioner” proteins for their roles in the cell. Some caspases are also required in the immune system for the maturation of lymphocytes. Failure of apoptosis is one of the main contributions to tumour development and autoimmune diseases; this, coupled with the unwanted apoptosis that occurs with ischemia or Alzheimer’s disease, has stimulated interest in caspases as potential therapeutic targets since they were discovered in the mid-1990s.”

vii. Darien scheme.

viii. Cinderella effect.

“The Cinderella effect is a term used by psychologists to describe the high incidence of stepchildren being physically abused, emotionally abused, sexually abused, neglected, murdered, or otherwise mistreated at the hands of their stepparents at significantly higher rates than at the hands of their genetic parents. It takes its name from the fairy tale character Cinderella, who in the story was cruelly mistreated by her stepmother and stepsisters.”

The article is messy and I mostly included it in this post to give you the above (most people don’t click the links anyway – which is fine!).

ix. Rotavirus. I remember reading a Danish article at some point about whether the vaccine against the Rotavirus A should be part of a national vaccine-program, but I can’t remember where I read about it. Why would you want a vaccine? Well:

“Rotavirus is the most common cause of severe diarrhoea among infants and young children,[1] and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five, nearly every child in the world has been infected with rotavirus at least once.[2] However, with each infection, immunity develops, and subsequent infections are less severe; adults are rarely affected.[3] There are five species of this virus, referred to as A, B, C, D, and E.[4] Rotavirus A, the most common, causes more than 90% of infections in humans.

The virus is transmitted by the faecal-oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis. Although rotavirus was discovered in 1973[5] and accounts for up to 50% of hospitalisations for severe diarrhoea in infants and children,[6] its importance is still not widely known within the public health community, particularly in developing countries.[7] In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock.[8]

Rotavirus is usually an easily managed disease of childhood, but worldwide nearly 500,000 children under five years of age still die from rotavirus infection each year[9] and almost two million more become severely ill.[7] […]

Rotavirus causes 37% of deaths attributable to diarrhoea and 5% of all deaths in children younger than five.[9]”

[my emphasis]

I think perhaps the numbers of some of the sources in the article are incorrect or mixed up, presumably because new sources have been added at a later point – maybe I’ll go have a closer look and/or edit it later. Anyway, [6] from above tempts me to add a ‘not in source given’ tag, because I could not see how that claim was supported by the article after searching the document and skimming it to figure out where the claim came from. Maybe I’ll do that later. The article linked to from [6] is on the economics of RV gastroenteritis and vaccination. On the other hand, this article (found through Scholar, maybe it’s also one of the sources in the article – I haven’t looked) – Nosocomial rotavirus infection in European countries: a review of the epidemiology, severity and economic burden of hospital-acquired rotavirus disease – does support the claim in the wikipedia article:

“The data currently available on the epidemiology, severity and economic burden of nosocomial rotavirus (RV) infections in children younger than 5 years of age in the major European countries are reviewed. In most studies, RV was found to be the major etiologic agent of pediatric nosocomial diarrhea (31-87%), although the number of diarrhea cases associated with other virus infections (eg, noroviruses, astroviruses, adenoviruses) is increasing quickly and almost equals that caused by RVs. Nosocomial RV (NRV) infections are mainly associated with infants 0-5 months of age, whereas community-acquired RV disease is more prevalent in children 6-23 months of age. NRV infections are seasonal in most countries, occurring in winter; this coincides with the winter seasonal peak of other childhood virus infections (eg, respiratory syncytial virus and influenza viruses), thus placing a heavy burden on health infrastructures. A significant proportion (20-40%) of infections are asymptomatic, which contributes to the spread of the virus and might reduce the efficiency of prevention measures given as they are implemented too late. The absence of effective surveillance and of reporting of NRV infections in any of the 6 countries studied (France, Germany, Italy, Poland, Spain and the United Kingdom) results in severe underreporting of NRV cases in hospital databases and therefore in limited awareness of the importance of NRV disease at country level. The burden reported in the medical literature is potentially significant and includes temporary reduction in the quality of children’s lives, increased costs associated with the additional consumption of medical resources (increased length of hospital stay) and constraints on parents’/hospital staff’s professional lives.”

If you, like me, didn’t know what a nocosomial infection is, well that’s just a hospital-acquired infection. RV-infections are not nocosomial infections.

Citations in the wikipedia article are also problematic because I became aware that not all of them are direct citations; for instance, [2] leads to this article – Rotavirus Overview: The Pediatric Infectious Disease Journal – but that’s a secondary source to the claim. The primary source is a CDC-report: “Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases. Atkinson W, Hamborsky J, McIntyre L, et al, eds. 10th ed. Washington, DC: Public Health Foundation; 2007:295-306.”

(Sorry for the lack of updates, this is a difficult time for me.)

February 26, 2012 Posted by | Anthropology, Archaeology, Data, History, Immunology, Infectious disease, Mathematics, Medicine, Physics, Psychology, Studies, Wikipedia | Leave a comment

Having fun

(Click to view full size:)

I spent most of the day doing exercises. 10 hours or so. Then an hour’s worth of reading on the side. I think perhaps I’d have found this stuff interesting 4-5 years ago.

Imagine how much fun it is to spend your Saturday doing this stuff while feeling guilty about not doing even more of it, even though you pretty much hate every second of your life you spend on it, all the while feeling that it’s futile anyway because you’ll probably just fail.

The funny thing is that if you add the total number of hours I’ve spent on this course (combined, remember that I’m retaking it this semester), I doubt anyone who got less than an A would be even close to that total time expenditure. I’ll consider myself very lucky if I get a C. I think he failed something like one-fourth/one-third of the class at the original exam in January.

Don’t expect answers to this post, I’ve been offline all day and I’m not sure I’ll go online again before the exam.

February 18, 2012 Posted by | Economics, education, Personal | Leave a comment

‘Why Nerds are Unpopular’ (some comments)

I have made this letter longer than usual, because I lack the time to make it short (Pascal)

I read Paul Graham’s essay some time ago, but I don’t think I’ve ever linked to it here. Since I recently had an excuse to read it again, I figured I might as well put up a link. It’s a very US-centric piece, but worth reading. A few passages from the post:

“And that, I think, is the root of the problem. Nerds serve two masters. They want to be popular, certainly, but they want even more to be smart. And popularity is not something you can do in your spare time, not in the fiercely competitive environment of an American secondary school. […]

For example, teenage kids pay a great deal of attention to clothes. They don’t consciously dress to be popular. They dress to look good. But to who? To the other kids. Other kids’ opinions become their definition of right, not just for clothes, but for almost everything they do, right down to the way they walk. And so every effort they make to do things “right” is also, consciously or not, an effort to be more popular.

Nerds don’t realize this. They don’t realize that it takes work to be popular. In general, people outside some very demanding field don’t realize the extent to which success depends on constant (though often unconscious) effort. For example, most people seem to consider the ability to draw as some kind of innate quality, like being tall. In fact, most people who “can draw” like drawing, and have spent many hours doing it; that’s why they’re good at it. Likewise, popular isn’t just something you are or you aren’t, but something you make yourself.

The main reason nerds are unpopular is that they have other things to think about. Their attention is drawn to books or the natural world, not fashions and parties.

But I think the main reason other kids persecute nerds is that it’s part of the mechanism of popularity. Popularity is only partially about individual attractiveness. It’s much more about alliances. To become more popular, you need to be constantly doing things that bring you close to other popular people, and nothing brings people closer than a common enemy.

Like a politician who wants to distract voters from bad times at home, you can create an enemy if there isn’t a real one. By singling out and persecuting a nerd, a group of kids from higher in the hierarchy create bonds between themselves. Attacking an outsider makes them all insiders. This is why the worst cases of bullying happen with groups.”

I think he overstates the case here:

“In almost any group of people you’ll find hierarchy. When groups of adults form in the real world, it’s generally for some common purpose, and the leaders end up being those who are best at it. The problem with most schools is, they have no purpose. But hierarchy there must be. And so the kids make one out of nothing.

We have a phrase to describe what happens when rankings have to be created without any meaningful criteria. We say that the situation degenerates into a popularity contest. And that’s exactly what happens in most American schools.”

However I couldn’t really say for sure because I’ve never set foot in an American high school. I don’t think this is the case in Denmark.

A funny thing about reading the essay was that while it would be easy for me to use my own experiences to affirm the theory of the ‘unpopular nerd’ in the 7-8th grade, a period where I was periodically bullied in school, I find that it does not very well match the (Danish) high-school experience. I btw. didn’t much think of myself as a nerd before the age of, what, 20? Nerds were other people, people much more strange than me – in my self-narrative, I didn’t get bullied because I was a nerd but because those other kids were jerks. I wasn’t really all that different from anyone else (so I told myself). I was told sometimes that I was a nerd in high school, but I shrugged it off because it didn’t matter, because I wasn’t. I didn’t have much clue when it came to the social dynamics of the high school environment, but I don’t think I was ever unpopular. I don’t think I was all that popular either – if so I didn’t notice – it was just that I didn’t pay much attention to that kind of stuff (about this part Graham is right). But an important observation here is that I was allowed not to care by the others.

Graham’s treatment of status as a unidimensional variable is of course a gross simplification of the actual dynamics. One thing I’d add related to the ‘important observation’ above is that whereas status might not be too complex to be semi-reliably measured on a unidimensional scale, it should indeed surprise us a great deal if people who did not do all that well on such a scale would care much about their ordering on such a scale, at least if given any choice in the matter. Any sort of aggregate popularity function would have to be constructed by aggregating stuff that in many cases has little to nothing to do with each other and we should expect people, especially people at the lower ends of the status spectrum, to actually only really care much about the status markers on which they do well. Everyone wants be think that s/he is better than other people, more deserving, so most people just pick a narrative that makes this (…idea? …delusion?) come true, which is one major reason why most people care about but a few dimensions of the social hierarchy. The flip side of the ‘nerds don’t care about being (conventionally) popular’ is that ‘there’s a lot of stuff non-nerds also don’t care about which makes them less popular among nerds’ (and/or other sub-groups) – so why do you care so much about the popularity functions of non-nerds?

Graham spends some time on that one, on why nerds care about the opinions of non-nerds. You have a real problem when you can find no dimensions where you do better than others, or at least no dimensions that many other people care about in the status game. One thing Graham isn’t explicit about though (have thought about?) is that status – like safety (…and money, and…) – is something that people will very often start to care a lot about when they don’t really have much of it. This angle is not really explored in his piece and I find it quite important: A very unpopular nerd probably is more status-conscious than the higher-status bully who makes his life miserable, because he’s forced to confront this aspect of his existence all the time; the bully isn’t. As a general rule, bullied people spend orders of magnitude more time thinking about bullying and related status-stuff than do bullies. I think Graham is missing that part of the equation – being unpopular makes you status-conscious, just like being poor makes you care more about money (maybe I should write a post about that one too? It seems to me that a lot of people with abundant resources are unaware of the fact that part of the reason why they don’t much ‘care about money’ is due to the fact that they have a lot of it, which is precisely what enables them to not care). Anyway, moving along that diagonal; perhaps the people who are (conventionally) popular in the eyes of people who are not don’t really know that they are popular? Perhaps it doesn’t even necessarily take a lot of work to become (conventionally) popular? That would be unfair, but that doesn’t make it wrong. Perhaps some popular high schoolers are just likeable people who do not need to actually do much to stay popular? Perhaps some of them – many of them? – are quite smart and could have become ‘nerds’ but instead decided not to?

Update: I decided to just get rid of four paragraphs because I didn’t much like how they turned out. If you were wondering about that Pascal quote in the beginning, the post used to be a lot longer. It turned out I did have the time to use the mouse to select those passages and delete them.

February 15, 2012 Posted by | Personal, Psychology | 5 Comments

The genetics of type 1 diabetes

There’s this question I’ve been asked many times: “Type 1 diabetes? Is that genetic?”

I was asked it again a couple of weeks ago and it caught me off-guard so I don’t think I was being quite as precise as I’d have liked to be – by having now written this post, I hope that I’ll do better next time (oh yes, there’ll be a next time…). Before going any further I should probably note here that even though I don’t know much about genetics, I estimate that I do know (/significantly?) more than most people who would choose to ask such a question: Having been exposed to stuff like Khan Academy, Razib Khan’s blog, Wikipedia (way too much to link to here), Russell, Dawkins and Majerus for instance means that I know the difference between a recessive allele and a linkage disequilibrium. It also means that I’m very inclined to answer a question like that one by asking another question: “What do you mean by ‘is it genetic?'” Genetics is complex stuff and there are many kinds of genetic disorders. I’ve tended to assume that people who ask do so more because of the implied blame-angle inherent in the question (‘it’s not your own fault you’re sick, right?’) than because of their deep interest in the disease etiology of type 1 diabetes – but I shouldn’t let that affect the way I respond, given that a reasonably clear answer to the question (…I assume they think they are asking) exists today (wikipedia):

“Type 1 diabetes is partly inherited and then triggered by certain infections, with some evidence pointing at Coxsackie B4 virus. There is a genetic element in individual susceptibility to some of these triggers which has been traced to particular HLA genotypes (i.e., the genetic “self” identifiers relied upon by the immune system). However, even in those who have inherited the susceptibility, type 1 diabetes mellitus seems to require an environmental trigger.”

So the simple version is that ‘genetics’ increases disease susceptibility and an infection then triggers the disease process. Here’s the abstract of a new study, Genetics of Type 1 Diabetes, by Steck and Rewers, providing a little more detail:

“BACKGROUND: Type 1 diabetes, a multifactorial disease with a strong genetic component, is caused by the autoimmune destruction of pancreatic β cells. The major susceptibility locus maps to the HLA class II genes at 6p21, although more than 40 non-HLA susceptibility gene markers have been confirmed.

CONTENT: Although HLA class II alleles account for up to 30%–50% of genetic type 1 diabetes risk, multiple non-MHC loci contribute to disease risk with smaller effects. These include the insulin, PTPN22, CTLA4, IL2RA, IFIH1, and other recently discovered loci. Genomewide association studies performed with high-density single-nucleotide–polymorphism genotyping platforms have provided evidence for a number of novel loci, although fine mapping and characterization of these new regions remain to be performed.

Children born with the high-risk genotype HLADR3/4-DQ8 comprise almost 50% of children who develop antiislet autoimmunity by the age of 5 years. Genetic risk for type 1 diabetes can be further stratified by selection of children with susceptible genotypes at other diabetes genes, by selection of children with a multiple family history of diabetes, and/or by selection of relatives that are HLA identical to the proband.

SUMMARY: Children with the HLA-risk genotypes DR3/4-DQ8 or DR4/DR4 who have a family history of type 1 diabetes have more than a 1 in 5 risk for developing islet autoantibodies during childhood, and children with the same HLA-risk genotype but no family history have approximately a 1 in 20 risk. Determining extreme genetic risk is a prerequisite for the implementation of primary prevention trials, which are now underway for relatives of individuals with type 1 diabetes.”

“Children born with the high-risk genotype HLADR3/4-DQ8 comprise almost 50% of children who develop antiislet autoimmunity by the age of 5 years” – in plain English, this means that almost half of all type 1 diabetics who show disease development before the age of 5 have this specific high-risk genotype. Note also how complex this disease is in terms of the genetics – ‘more than 40 non-HLA susceptibility gene markers have been confirmed’. Maybe some of them are just flukes due to p-value hunting, but that’s a lot of genes impacting disease risk.

Steno has some stuff in Danish here if people are interested. According to their numbers, if the mother has type 1 diabetes there’s a 2% risk that her child will have the disease. If the father has the disease the risk is 5%. Lægehåndbogen states that for monozygotic twins, if one twin develops the disease the risk that the other twin will also get it is 50%.

February 11, 2012 Posted by | Diabetes, Epidemiology, Genetics, Immunology, Medicine, Studies | 1 Comment

Wikipedia articles of interest

1. Economy of the Han Dynasty. I’ve read about this elsewhere as well, but it turns out that wikipedia has some good stuff on the subject (‘Han Dynasty’ is one of Wikipedia’s featured topics).

2. Effect of psychoactive drugs on animals. It’s not a long article, but I had to link to it because of these awesome images:

If you’d rather read about the caffeine that’s having such a huge effect on spiders, here’s the article. Here’s one bit that I found interesting:

“Extreme overdose can result in death.[48][49] The median lethal dose (LD50) given orally, is 192 milligrams per kilogram in rats. The LD50 of caffeine in humans is dependent on individual sensitivity, but is estimated to be about 150 to 200 milligrams per kilogram of body mass or roughly 80 to 100 cups of coffee for an average adult.[4] Though achieving lethal dose with caffeine would be exceptionally difficult with regular coffee, there have been reported deaths from overdosing on caffeine pills, with serious symptoms of overdose requiring hospitalization occurring from as little as 2 grams of caffeine. An exception to this would be taking a drug such as fluvoxamine or levofloxacin, which blocks the liver enzyme responsible for the metabolism of caffeine, thus increasing the central effects and blood concentrations of caffeine five-fold.[47][48][49][50] Death typically occurs due to ventricular fibrillation brought about by effects of caffeine on the cardiovascular system.”

3. Schwarzschild radius.

“The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is the distance from the center of an object such that, if all the mass of the object were compressed within that sphere, the escape speed from the surface would equal the speed of light.” (The article has much more.)

4. Peasants’ Revolt.

“The Peasants’ Revolt, Wat Tyler’s Rebellion, or the Great Rising of 1381 was one of a number of popular revolts in late medieval Europe and is a major event in the history of England. Tyler’s Rebellion was not only the most extreme and widespread insurrection in English history but also the best-documented popular rebellion to have occurred during medieval times. The names of some of its leaders, John Ball, Wat Tyler and Jack Straw, are still familiar in popular culture, although little is known of them.

The revolt later came to be seen as a mark of the beginning of the end of serfdom in medieval England, although the revolt itself was a failure. It increased awareness in the upper classes of the need for the reform of feudalism in England and the appalling misery felt by the lower classes as a result of their enforced near-slavery.”

5. Przewalski’s horse.

I found the information about the conservation efforts fascinating – this species was saved even though it was about as close to extinction as a species could possibly get. And not only did they survive, some have even been succesfully reintroduced into the wild:

“Przewalski’s horse […] or Dzungarian horse, is a rare and endangered subspecies of wild horse (Equus ferus) native to the steppes of central Asia, specifically China and Mongolia.[3] At one time extinct in the wild, it has been reintroduced to its native habitat in Mongolia at the Khustain Nuruu National Park, Takhin Tal Nature Reserve and Khomiin Tal. […]

The world population of these horses are all descended from 9 of the 31 horses in captivity in 1945.[9] These nine horses were mostly descended from approximately 15 captured around 1900. A cooperative venture between the Zoological Society of London and Mongolian scientists has resulted in successful reintroduction of these horses from zoos into their natural habitat in Mongolia; and as of 2011 there is an estimated free-ranging population of over 300 in the wild.[10] The total number of these horses according to a 2005 census was about 1,500.”

Here are some related links.

6. Strategic dominance (game theory).

7. Collatz conjecture.

“Take any natural number n. If n is even, divide it by 2 to get n / 2. If n is odd, multiply it by 3 and add 1 to obtain 3n + 1. Repeat the process (which has been called “Half Or Triple Plus One”, or HOTPO[4]) indefinitely. The conjecture is that no matter what number you start with, you will always eventually reach 1. The property has also been called oneness.[5]” (long article, lots of stuff including several examples.)

February 9, 2012 Posted by | Astronomy, Biology, economic history, Economics, Game theory, History, Mathematics, Physics, Wikipedia, Zoology | Leave a comment

Quotes

1. “Books are the best things, well used: abused, among the worst.” (Ralph Waldo Emerson)

2. “Manners are a sensitive awareness of the feelings of others. If you have that awareness, you have good manners, no matter what fork you use.” (Emily Post)

3. “Susan: ‘Lemont, have you ever noticed how in comic strips and sitcoms, the men are usually clueless victims of life, while the women are wise and have their lives in order?’
Lemont: ‘Another bad day at work Susan?’
Susan: ‘Why can’t my life be like a f*ckin’ comic strip!!!'” (Candorville, via tvtropes)

4. “To doubt everything or to believe everything are two equally convenient solutions; both dispense with the necessity of reflection.” (Henri Poincaré)

5. “When even the brightest mind in our world has been trained up from childhood in a superstition of any kind, it will never be possible for that mind, in its maturity, to examine sincerely, dispassionately, and conscientiously any evidence or any circumstance which shall seem to cast a doubt upon the validity of that superstition. I doubt if I could do it myself.” (Mark Twain)

6. “It is well for one to know more than he says.” (Plautus).

7. “I recommend you to take care of the minutes, for the hours will take care of themselves.” (Philip Stanhope, 4th Earl of Chesterfield)

8. “A thought is often original, though you have uttered it a hundred times.” (Oliver Wendell Holmes, Sr.)

9. “I watched a nature program on TV last night. Afterward, I asked dad if life was really nothing more than trying to survive long enough to reproduce before you became food for something else.” “What did he say?” “Well, he looked at me a minute, and said he didn’t know anything about the rest of it, but he thought that the importance of reproducing was greatly overrated.” (Calvin and Hobbes)

10. Calvin: “You know what I’ve noticed, Hobbes? Things don’t bug you if you don’t think about them. So from now on, I simply won’t think about anything I don’t like, and I’ll be happy all the time.” Hobbes: “Don’t you think that’s a pretty silly and irresponsible way to live?” Calvin [looking away from Hobbes, up into the sky]: “What a pretty afternoon.” (Calvin and Hobbes)

11. “Unwanted favours gain no gratitude.” (Sophocles)

12. “Events will take their course, it is no good of being angry at them; he is happiest who wisely turns them to the best account.” (Euripides)

13. “You are not the king of your brain. You are the creepy guy standing next to the king going “a most judicious choice, sire”.” (Steven Kaas, via lesswrong)

February 7, 2012 Posted by | Quotes/aphorisms | Leave a comment

Random thoughts on dating

In general, it is “the act of meeting and engaging in some mutually agreed upon social activity in public, together, as a couple.” I’ll limit the following to the ‘go have something to eat together’-variation, but many of these considerations are general enough to be applied in other contexts as well. I’ve been thinking a bit about this stuff now, and I thought it’d be a good idea to just write down some of the ideas I’ve had. This is not well-known territory to me, so I’d not be surprised if most of it is stuff you guys have already internalized.

So anyway: The basic idea is that you meet, you go have a meal together (or do some other activity, but let’s stick with the meal for now). While you’re having the meal you talk, and after you’re done you either go someplace else to talk some more or you go your separate ways right away. I know that some dates end differently, but let’s disregard those here. It should be easy, right? Not too complicated. Then you start to think about it.

It’s very easy to forget how complex human social interaction is.

Before the date ever starts X […one of the daters; Y denotes the other dater – the terms are not gender-specific] needs to think about a few things. The good old: What to wear? Clothes are signalling devices, whether used consciously that way or not. Worth remembering here is that signals can be misinterpreted, so the concept of risk and how an individual deals with it enters the equation long before the date actually starts. The weights of many of the relevant variables here are somewhat gender-specific – it seems that women spend more time getting ready than do men on average. Clothes is but one element: A male will for instance be likely to ask himself whether he should shave, or whether to put on a deodorant or aftershave; females will on the other hand often think about whether to put on make-up, how much -ll-, how to set their hair, whether to use nail-polish or not, which earrings, if any, to wear – and lots of other things I haven’t thought about. Note that not taking a conscious decision about these variables is itself a decision, a signal. There is no way to opt out of the signalling game even though perhaps you’d like to do that.

There are a few other considerations which are of relevance to the date but enter the equation before the date ever takes place: Where and when to meet, who gets to decide that/-what, which mode of transport to use to get there? There’s hidden complexity behind all these variables: The decisions about where to meet and who decides confer information about the price of the date, which can be thought of as both a signal related to willingness to spend and income. Willingness to spend can easily be interpreted as a signal of the commitment level from the outset. This pre-date variable can also confer information about traits like aggressiveness and dominance (if one partner really wants to go somewhere specific or refuses to go to one specific restaurant), which again relates to status (an individual that considers him/herself lower status than the other is ceteris paribus less likely to make demands). Willingness- and ability to compromise, variables which tend to be quite important when it comes to long-term relationship success, also indirectly enter the equation at this point. Mode of transport relates to distance, which again might in some cases relate to commitment, but it also relates to the risk profile; how much trouble does/did an individual go through to avoid being late? Which again can, but needn’t necessarily, be interpreted as a signal regarding the initial commitment level. Note here that a signal conferring a high initial commitment level need not necessarily be interpreted by the other party in a positive way: If X puts a lot of time/effort into a date, X might do it because X really likes Y or want to get to know Y – but perhaps it might also be the case that X has limited options, a factor which most often will impact Y’s evaluation of X negatively.

Having all that stuff out of the way: So now you meet, you sit down somewhere, you order food and you start to talk. Before getting to the whole interaction part it’s worth noting that this social exchange does not take place in a vacuum. There are other people around, perhaps many people. How close do you sit to the next table, how often will a waiter or owner intrude upon your conversation, what’s the noise level, is it at an ‘exposed’ location or somewhat private? In cases where the venue was decided upon by one party and the other party did not know anything about the venue, what the place is like both relates to what will be going on during the date (some subjects will probably not come up during the discussion if there are 10 other strangers sitting within 20 feet..) and it also enters the equation in relation to which variables the deciding party might have emphasized in the pre-date phase, and what this tells the other party. Some people don’t handle lots of people very well and others do, some people perhaps don’t handle background noise (like music playing in the background) very well. There can be multiple reasons for such differences in the ability to deal with the environment and they need not all relate to innate personality traits; perhaps the difference is rather due to a factor like hearing impairment. It’s actually quite easy for a deciding party to send a signal he or she is not even remotely aware of, especially on a first date where neither party will have an extensive knowledge about the other party’s preferences. Which sort of venue is chosen will probably generally depend on the number of dates; if it’s a first date, the most convenient place to meet for most people will be somewhere very public, close to a lot of people and a place where it is easy to get away quite fast. Females in particular will focus on these aspects to have easy exit routes in case it turns out the guy is a creep; other steps to minimize risk that might deserve consideration, particularly for a female on her way to a first date with a stranger, would be to share information like time and place about the date with a friend or family member and/or have someone call during or after the date to make sure nothing bad has happened. On subsequent dates such considerations will of course carry less weight. Note that past experiences can have a significant impact on the evaluation of the date, especially if the other party has had a bad experience in the past.

When evaluating the course of the date it is important to note that there are many things besides external environmental factors that potentially need to be taken into account; multiple other factors more or less completely outside the control of an individual can impact the experience positively or negatively: X might be stressed from work, X might be tired because s/he didn’t sleep well the day before, X might have a cold. Biological factors which neither individual perhaps knows about can even impact behaviour during the date: Female ovulation impacts both the behaviour of the female herself and the behaviour of nearby males.

Next, the interaction part. Before going into the verbal exchanges that take place during such an encounter, remember that a lot of human communication is non-verbal. Does the other person initiate eye contact, and if not what does this mean – does it mean that the person in front of you is a convicted serial killer on the run from the law, or is the explanation perhaps that the person is just insecure? Recall here that there can be many reasons for insecurity, and that not all of them are equally impermissible in the status game. Recall also that there is a double standard at work here, because female insecurity is less likely to have a negative impact on (/potential) partner evaluation than is male insecurity. A few other examples of body language that might be important to pick up on: Does Y tilt the head while X is talking, and does X pick up on it? What does head tilting mean – that Y is bored, that Y is interested or that Y did not have a lot of sleep last night? Does X slouch and if so, what does that mean? When Y frequently looks at his or her watch, that’s probably most often a bad sign indicating boredom. Body language is usually very dynamic and it conveys important information, but when you don’t know the other party very well, it can be hard to interpret. Sometimes commenting on body language can be risky, especially if it indicates that the date is perhaps not going very well; in those cases, it will sometimes be preferable to make a mental note of the non-verbal signal and try to change the subject or in some other way engage the problem. Some people have a harder time interpreting body language than others, something one might wish to take into account when evaluating later on – social skills will often be important when evaluating partner potential, but trouble with body language need not equate or indicate lack of interest.

When it comes to verbal interaction, there are a few key variables here. One is the total information supplied during the date. Another is the total time spent talking. A third is communication efficiency (information/unit of time spent talking). Some people are more efficient communicators than others and in some cases this variable will be of interest to the other dater. If a person talks a lot but doesn’t say much, it can be an indicator of insecurity, it can be an indicator of below-average communication skills or perhaps it can be an indicator of egocentrism and/or inconsideration. It is possible to interpret behaviour like that in a positive light (‘he’s already falling in love with me and that’s why he behaves like a third-grader!), but most often such behaviour will probably be considered a liability rather than an asset. If X spends a lot of time talking about himself, something most people love to do if given the chance, it might indicate that he doesn’t have a great deal of interest in Y (or he would ask questions about Y). If Y keeps asking X questions and seems unwilling to share much information about him-/herself, that might also be a signal of insecurity. Or it might be a signal that X is very interested in Y. Or it might be a signal that Y considers him/herself higher status than X, and is entitled to more information than X. Having the evolutionary context of human mating behaviour in mind, it’s probably the case that females will on average share less information about themselves and demand more information about the other than will males, especially over the course of the first dates. If the male is low-quality, the female will want to know as soon as possible and screening requires information.

What to talk about? That question is opening up a whole can of worms and I will not go into much detail here. It will generally depend on the education level of the parties present, the (/shared?) interests, the feedback supplied over the course of the date (including non-verbal cues), the age, etc. Path dependence can turn out to be important, which is another way of saying that people should be careful about what to share and what to ask about, perhaps particularly when on a first date with a person one doesn’t know. This brings me to another key variable: What not to say. This one is very context-dependent, but in general a male is probably required to share a bit more information than is a female and thus he is less likely to ‘get a free pass’ on a particular question. Even though the information requirements are not symmetric, there are still some norms regarding what constitutes a ‘proper ratio’ of information exchange. Diverging from the norms and the proper information exchange ratios can be risky, as I alluded to earlier. In a similar vein, it’s important to give some thought as to how to deal with a refusal to answer a specific question. It might be a red flag. It might be nothing. Perhaps it’s something, but something Y is not comfortable talking about. If Y says that talking about a particular subject makes him/her uncomfortable, in my mind it would be beyond inconsiderate for X to refuse to change the subject. Some people however would consider the efficiency argument more important; they’d weigh the value of getting a dealbreaking red flag out into the open right away, regardless of the feelings of the other party, higher than the risk that the other partner would lose interest because of bad manners. Either way, naturally it’s impossible to avoid all ‘unpleasant questions’, as many implicit screening questions will necessarily be somewhat unpleasant to answer for people who do not meet the criteria required (and an important part of the dating process is precisely to weed out the incompatible matches).

When dating, there’s always stuff you don’t want the other party to know (/now, /yet, /ever?). There’s stuff you want to emphasize and stuff you don’t want to talk about. People who date are never fully committed to the ‘just be yourself’-advice. At best, people commit to a ‘be who I think I am’ or a ‘be who I’d like to be’-strategy. Sometimes people lie more or less openly when they are dating. This is a risky strategy which probably decreases the likelihood of a successful long-term relationship but might be an effective strategy when it comes to increasing the potential for short-term success. But nobody is completely honest during a date – either with themselves or with the partner – and that’s worth remembering when you find out something about the other person that makes the other individual look less trustworthy. The funny thing is that most people who lie to themselves about who they are before they meet the partner and then act in a deceitful manner while they are dating because of the lies they’ve told themselves, probably most often think that they are behaving in a perfectly honest manner. Some people are better liars than others and the best lie is the lie that you yourself believe to be true.

If you wanted a conclusion of some sort, I know very well that the above considerations amount to little more than just saying that ‘dating is complex’. That was part of the whole point. Here’s xkcd on related matters. If you haven’t already read it, I also encourage you to read this previous post on ‘Rational romantic relationships‘.

February 5, 2012 Posted by | dating, Psychology | Leave a comment

Promoting the unknown, a continuing series

(as to the last one, I know I’ve said it before: Alkan isn’t for everyone. But if your reaction is something along the lines of: ‘Yeah, well, I mean, it’s a nice piece and all – but nothing special’ – then you should probably think about the fact that Hamelin plays this piece with only one hand. Here’s another one of those performances with image as well as sound. Here’s yet another (the second piece played))

February 3, 2012 Posted by | Music | Leave a comment

Divorce and marriage patterns, some Danish data

I decided to follow up on this post and have a closer look at the Danish numbers. In the post I’ve used data from Statistics Denmark’s public database (Statistikbanken). First, let’s just have a look at the raw numbers (from: ‘SKI107: Skilsmisser fordelt efter parternes bopæl, alder og ægteskabets varighed’):

The above graph displays the total number of divorces as a function of the length of marriage for the divorces that happened in Denmark during the year 2010. To take an example, 911 couples divorced after 3 years of marriage. Divorce risk as a function of marriage duration is pretty much (though not completely) monotonically decreasing over time (yes, I know it’s problematic to extrapolate from cross-sectional data like this, but let’s just pretend for a moment that this makes sense anyway…) after the first decade of marriage. When looking only at the first 10-15 years the distribution looks a bit bimodal. Actually, I can’t help remarking here more specifically that when it comes to the 7th year, the divorce risk is actually lower than it is for any other marriage duration in the 0-9 year span except for the first two years of marriage – i.e. the 7 year mark is a local minimum. There were 148 divorces at the 25-year mark, but only 93 divorced after 27 years of marriage. This is not to say that the risk of divorce at the 25-year mark is high – it’s almost twice as high for marriages that have lasted exactly 20 years (291) – but the risk doesn’t really tail off there, rather it does it a couple years later (in terms of marriage duration). The total number of divorces in 2010 was 14292, or about 39 each day of the year. I found it interesting that whereas people are much more likely to marry during the summer, there does not seem to be much systematic variation in the divorce rate over the course of the year – but you can judge yourself, here are the data from 2010 (‘BEV3C: Vielser og skilsmisser på måneder’):

[‘2010M01’ = First month of 2010 (and so on)]

Back to the other data set, if we once again assume that the age/duration profile of divorcees/divorces do not change much over time so that we can extrapolate from the data we have, and you then decide to condition on a divorce actually happening during a marriage, what is then the likelihood that a marriage that will fail will end at year X? (To make this absolutely clear: This is not the probability that a marriage that has lasted X years will end in divorce during that year.)

If you instead look at the cumulative distribution function, it looks like this:

I cut it off after 20 years – more than 85% of all divorces are accounted for by then and adding more numbers seemed counterproductive because it made it harder to see what was going on to the left of the graph – where the most important stuff’s going on – in detail. More than half of the marriages that ended in divorce in 2010 were marriages between partners who had been together for 9 years or less. 73% of them were between partners who’d been together for 15 years or less. Almost one fourth of them (24%) had only lasted 4 years or less.

February 1, 2012 Posted by | Data, Demographics, marriage | Leave a comment