Econstudentlog

Stuff

I spent the weekend with my family, but along the way I realized that I’m way behind on the blogging (compared to how much I’ve read). I’ll not write too much about each subject as it would otherwise become a very long post, but I hope you’ll click a few of the links:

i. 2008 WORLD DRUG REPORT by The United Nations’ Office on Drugs and Crime. ‘Read it for the data’, if you’re interested in that kind of stuff. Here’s one related article. Here’s another, not for the fainthearted.

ii. Revisiting Truth or Triviality: The External Validity of Research in the Psychological Laboratory, by Gregory Mitchell.

iii. A-not-B error.

iv. An interview with a guy who wrote a book. The book is called ‘Ignorance’. I’m currently considering buying said book.

v. Vaughan Bell: the truth about lie detectors.

vi. Coursera. I was considering signing up for the Introduction to logic course (I still am). If you haven’t heard about the site, go have a look.

vii. PLoS Biology: How Many Species Are There on Earth and in the Ocean? Short answer: We have no idea. “In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description.”

viii. To Detect Cheating in Chess, a Professor Builds a Better Program. According to the work this guy’s done, rating-inflation is not as much of a problem as some people like to think: Super-GMs today are just incredibly strong, also compared to top players, say, 50 years ago (so it makes sense that their ratings are higher):

“He has also discovered that the way people play has evolved. According to his analysis, the player now ranked No. 40 in the world plays as well as Anatoly Karpov did in the 1970s, when he was world champion and was described as a machine.”

ix. How does a gravity slingshot work?

x. Cartoon Laws of Physics. I knew many of these, but it’s nice to have them written down somewhere.

xi. I’ve linked to this on twitter too, but it’s worth including here as well: PLoS ONE: The Impact of Long-Term Exposure to Space Environment on Adult Mammalian Organisms: A Study on Mouse Thyroid and Testis. Short version: Judging from these results, long-term exposure to space (microgravity, radiation) is bad for your thyroid (and, if you’re a male, your testicles). A short spacetrip is probably not the way to boost your sperm-count: “Very low sperm numbers were noted in both WT and TG spaceflight mice (−90%, −94%, −92% and −89% vs. laboratory and ground controls, respectively”

xii. FUD (Fear, uncertainty and doubt).

xiii. Galaxy formation and evolution.

xiv. A video on why we have blind spots:

xv. Delian League.

xvi. Sometimes men like women like the Chinese like pork. A good post by Razib Khan, I really liked this one: “It it is sometimes said that women civilized men, but I have long held that men created civilization only to impress women.”

April 30, 2012 Posted by | Astronomy, Chess, History, Medicine, Papers, Physics, Psychology, Random stuff, Wikipedia | 4 Comments

I try to keep this in mind…

“Today, I told my boyfriend I was leaving him because he’s cheating on me. He then told me he will die without me. When I said that I didn’t care, he said ‘OK. I’ll kill myself!’ and then held his breath in attempt to suffocate himself. I can’t believe I dated this idiot.”

“Today, I had to take an emergency contraceptive. I was talking to my boyfriend about it, and I told him that my stomach really hurt. His response? “Aw. That’s just the baby dying.”

“Today, I finally found out whether or not my boyfriend is cheating on me. Turns out he isn’t. He is cheating on his wife, with me.”

“Today, I told my boyfriend I wanted to see more of his passionate side. He pushed my head down towards his lap.”

“Today, my 21 year old boyfriend asked me what foreplay is.”

“Today, my boyfriend confessed that he felt so insecure he submerged my $80 vibrator in water to eliminate the competition.”

“Today, I had to cancel my wedding because my fiancé is so hungover from his bachelor party, he’s throwing up all over the place, can’t stand up straight and is calling me by the stripper’s name he met yesterday night.”

All the quotes are from FML. Or what about this guy, he’s a real catch too:

Here’s a somewhat related post from the past. Of course this is somewhat hyperbolic, but it doesn’t really change the fact that actually, compared to a lot of males I’m a real catch.

I think a majority of the people whom I consider reasonably close friends in real life are in the IQ-130+ category. Granted, there aren’t all that many of them and there’s some uncertainty, but I’m reasonably sure about this. They’re also mostly pleasant people who behave well. Educated. Almost exclusively male.

Of course I’m biased – these are people who like spending time with me and whom I consider agreeable, and as Rochefoucauld would say: We hardly find any persons of good sense, save those who agree with us. But either way, in a social setting/sphere like this it is easy to get a messed up perspective when it comes to what other people are generally like, and about stuff like whom you are competing against in the dating/partnership setting. Sure, I do implicitly compete against some of these kinds of people too; but it’s worth always having in mind that most people aren’t like that. This is an easy thing to forget, and forgetting it might mean that you are drawing faulty inferences about other stuff. Faulty inferences you’re not even aware you’ve ever drawn.

Incidentally, on another note I think a lot of smart people sometimes behave as if they are not in fact very smart around people who are not very smart; social skills take time and effort to develop and maintain, and it is highly context-dependent which factors are actually important in the social equation. The fact that there does not just exist one single, all-encompassing social learning curve, but rather a variety of different social learning curves for different population segments, is an underappreciated insight. Sometimes the slopes are different. Sometimes the variables affecting the slopes are.

April 27, 2012 Posted by | dating, Personal, Random stuff | Leave a comment

The Pale Blue Dot

Wikipedia. Do go have a look at that image.

If you have time, I’ll once again recommend Khan Academy’s Cosmology and Astronomy section – if you have never read about this kind of stuff, the first 5 or 6 videos will blow your mind.

April 24, 2012 Posted by | Astronomy | Leave a comment

Wikipedia articles of interest

i. Ironclad warship.

“An ironclad was a steam-propelled warship in the early part of the second half of the 19th century, protected by iron or steel armor plates.[1] The ironclad was developed as a result of the vulnerability of wooden warships to explosive or incendiary shells. The first ironclad battleship, La Gloire, was launched by the French Navy in November 1859.[2] […]

The rapid evolution of warship design in the late 19th century transformed the ironclad from a wooden-hulled vessel that carried sails to supplement its steam engines into the steel-built, turreted battleships and cruisers familiar in the 20th century. This change was pushed forward by the development of heavier naval guns (the ironclads of the 1880s carried some of the heaviest guns ever mounted at sea), more sophisticated steam engines, and advances in metallurgy which made steel shipbuilding possible.

The rapid pace of change in the ironclad period meant that many ships were obsolete as soon as they were complete, and that naval tactics were in a state of flux. Many ironclads were built to make use of the ram or the torpedo, which a number of naval designers considered the crucial weapons of naval combat. There is no clear end to the ironclad period, but towards the end of the 1890s the term ironclad dropped out of use. New ships were increasingly constructed to a standard pattern and designated battleships or armored cruisers. […]

From the 1860s to the 1880s many naval designers believed that the development of the ironclad meant that the ram was again the most important weapon in naval warfare. With steam power freeing ships from the wind, and armor making them invulnerable to shellfire, the ram seemed to offer the opportunity to strike a decisive blow.

The scant damage inflicted by the guns of Monitor and Virginia at Battle of Hampton Roads and the spectacular but lucky success of the Austrian flagship Ferdinand Max sinking the Italian Re d’Italia at Lissa gave strength to the ramming craze.[30] From the early 1870s to early 1880s most British naval officers thought that guns were about to be replaced as the main naval armament by the ram. Those who noted the tiny number of ships that had actually been sunk by ramming struggled to be heard.[31]

The revival of ramming had a significant effect on naval tactics. Since the 17th century the predominant tactic of naval warfare had been the line of battle, where a fleet formed a long line to give it the best fire from its broadside guns. This tactic was totally unsuited to ramming, and the ram threw fleet tactics into disarray. The question of how an ironclad fleet should deploy in battle to make best use of the ram was never tested in battle, and if it had been, combat might have shown that rams could only be used against ships which were already stopped dead in the water.[32]”

This is how one of them looked like, click to view full size*:

ii. Allometry. John Hawks talked about this a bit in one of his lectures, I decided to look it up:

“Allometry is the study of the relationship of body size to shape,[1] anatomy, physiology and finally behaviour […] Allometry often studies shape differences in terms of ratios of the objects’ dimensions. Two objects of different size but common shape will have their dimensions in the same ratio. Take, for example, a biological object that grows as it matures. Its size changes with age but the shapes are similar. […]

In addition to studies that focus on growth, allometry also examines shape variation among individuals of a given age (and sex), which is referred to as static allometry. Comparisons of species are used to examine interspecific or evolutionary allometry […]

Isometric scaling occurs when changes in size (during growth or over evolutionary time) do not lead to changes in proportion. […] Isometric scaling is governed by the square-cube law. An organism which doubles in length isometrically will find that the surface area available to it will increase fourfold, while its volume and mass will increase by a factor of eight. This can present problems for organisms. In the case of above, the animal now has eight times the biologically active tissue to support, but the surface area of its respiratory organs has only increased fourfold, creating a mismatch between scaling and physical demands. Similarly, the organism in the above example now has eight times the mass to support on its legs, but the strength of its bones and muscles is dependent upon their cross-sectional area, which has only increased fourfold. Therefore, this hypothetical organism would experience twice the bone and muscle loads of its smaller version. This mismatch can be avoided either by being “overbuilt” when small or by changing proportions during growth […] Allometric scaling is any change that deviates from isometry. […]

In plotting an animal’s basal metabolic rate (BMR) against the animal’s own body mass, a logarithmic straight line is obtained. Overall metabolic rate in animals is generally accepted to show negative allometry, scaling to mass to a power ≈ 0.75, known as Kleiber’s law, 1932. This means that larger-bodied species (e.g., elephants) have lower mass-specific metabolic rates and lower heart rates, as compared with smaller-bodied species (e.g., mice), this straight line is known as the “mouse to elephant curve”.

iii. Arthropod.

“An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda (from Greek ἄρθρον árthron, “joint”, and ποδός podós “leg”, which together mean “jointed leg”), and include the insects, arachnids, crustaceans, and others. Arthropods are characterized by their jointed limbs and cuticles, which are mainly made of α-chitin; the cuticles of crustaceans are also biomineralized with calcium carbonate. The rigid cuticle inhibits growth, so arthropods replace it periodically by molting. The arthropod body plan consists of repeated segments, each with a pair of appendages. It is so versatile that they have been compared to Swiss Army knives, and it has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living animal species, and are one of only two animal groups that are very successful in dry environments – the other being the amniotes. They range in size from microscopic plankton up to forms a few meters long.”

Another way to put it – it’s these guys:

I thought the stuff on molting (Ecdysis) was interesting:

“The exoskeleton cannot stretch and thus restricts growth. Arthropods therefore replace their exoskeletons by molting, or shedding the old exoskeleton after growing a new one that is not yet hardened. Molting cycles run nearly continuously until an arthropod reaches full size.[22] […] In the initial phase of molting, the animal stops feeding and its epidermis releases molting fluid, a mixture of enzymes that digests the endocuticle and thus detaches the old cuticle. This phase begins when the epidermis has secreted a new epicuticle to protect it from the enzymes, and the epidermis secretes the new exocuticle while the old cuticle is detaching. When this stage is complete, the animal makes its body swell by taking in a large quantity of water or air, and this makes the old cuticle split along predefined weaknesses where the old exocuticle was thinnest. It commonly takes several minutes for the animal to struggle out of the old cuticle. At this point the new one is wrinkled and so soft that the animal cannot support itself and finds it very difficult to move, and the new endocuticle has not yet formed. The animal continues to pump itself up to stretch the new cuticle as much as possible, then hardens the new exocuticle and eliminates the excess air or water. By the end of this phase the new endocuticle has formed. Many arthropods then eat the discarded cuticle to reclaim its materials.[22]

Because arthropods are unprotected and nearly immobilized until the new cuticle has hardened, they are in danger both of being trapped in the old cuticle and of being attacked by predators. Molting may be responsible for 80 to 90% of all arthropod deaths.[22]”

It’s a long article, and it has a lot of good stuff (and lots of links).

iv. Scottish independence referendum, 2014. I did not know about this.

v. Coordination game.

“In game theory, coordination games are a class of games with multiple pure strategy Nash equilibria in which players choose the same or corresponding strategies. Coordination games are a formalization of the idea of a coordination problem, which is widespread in the social sciences, including economics, meaning situations in which all parties can realize mutual gains, but only by making mutually consistent decisions. […]

A typical case for a coordination game is choosing the side of the road upon which to drive, a social standard which can save lives if it is widely adhered to. […] In a simplified example, assume that two drivers meet on a narrow dirt road. Both have to swerve in order to avoid a head-on collision. If both execute the same swerving maneuver they will manage to pass each other, but if they choose differing maneuvers they will collide. […] In this case there are two pure Nash equilibria: either both swerve to the left, or both swerve to the right. In this example, it doesn’t matter which side both players pick, as long as they both pick the same. Both solutions are Pareto efficient. This is not true for all coordination games”

vi. Ostrogothic Kingdom. Of course Heather is the reason why I read that article. At its greatest extent, the kingdom looked roughly like this:

I have not yet read all of the relevant material covering this subject in Heather, so I don’t know the extent to which he (or others) disagrees with Bury (who seems to be the main source of the article). But if you didn’t know there was such a thing as an Ostrogothic Kingdom in the first place, reading the article will probably not be a step in the wrong direction.

vii. Speleology. Yet another one of those areas of research you have probably never thought about:

“Speleology (also spelled spelæology or spelaeology) is the scientific study of caves and other karst features, their make-up, structure, physical properties, history, life forms, and the processes by which they form (speleogenesis) and change over time (speleomorphology). The term speleology is also sometimes applied to the recreational activity of exploring caves, but this is more properly known as caving, spelunking or potholing. Speleology and caving are often connected, as the physical skills required for in situ study are the same.

Speleology is a cross-disciplinary field that combines the knowledge of chemistry, biology, geology, physics, meteorology and cartography to develop portraits of caves as complex, evolving systems.”

I thought the article on troglobites (small cave-dwelling animals which live permanently underground and cannot survive outside the cave environment), which it links to, was interesting too.

* I decided to present the readers with an alternative way to post images on the blog, which I’m considering applying in the future. I have been made aware that the current modus operandi, posting pictures full-size in the posts, is not always optimal given the readers’ preferences regarding browsers and which tools with which to access the site (‘modern gadgets’ vs PC). I should make it clear that if you read this blog using a PC in a firefox browser with a pretty standard screen resolution, it looks fine. Because that’s how I access and view the site.

I am, and have been for a very long time, afraid that the blog will turn too much into a wall of text and I keep reminding myself that I should take active countermeasures to prevent this from happening. I don’t care that much about illustrations and images, but I know that many people do. Is this way of presenting images which I have applied in the post – relatively small thumbs which you can click if you want to see them in full size – (much) better than the alternative?

One more thing. I know that it’s quite possible that the reason stuff like images sometimes look like crap is because the chosen theme for the blog is not optimal. But I also know that the last time I changed the theme, everything went to hell and it took me days to handle the problems which the theme change caused. That was, mind you, at a point in time where the number of posts was less than a fourth of what it is today. If I change the theme, it affects at least every post I’ve written in the last 4 years. I have no idea how it will impact stuff like videos. So even if the theme is not optimal, changing it is not an option if I can avoid it.

April 22, 2012 Posted by | Biology, blogging, Game theory, Geology, History, Paleontology, Wikipedia, Zoology | 1 Comment

Quotes

Many of the quotes below are from this book. I decided to post quite a few of the ones which were impossible for me to source. If you know the source to one or more of those quotes, please enlighten me in the comment section.

i. “Men dissimulate their dearest, most constant, and most virtuous inclination from weakness and a fear of being condemned.” (Luc de Clapiers, Marquis de Vauvenargues)

ii. “It usually takes two people to make one of them angry” (attributed (?) Laurence Peter)

iii. “Few men speak humbly of humility, chastely of chastity, skeptically of skepticism.” (Pascal)

iv. “The most trying of social duties is to appear interested in the things that don’t interest you.” (unknown)

v. “Good judgment comes from experience, and experience comes from bad judgment.” (Rita Mae Brown)

vi. “Nobody loses anything by being polite, but there are a lot of people who seem afraid to take the risk.” (unknown)

vii. “An inferiority complex is the only trait which enables us to see ourselves as others see us.” (unknown)

viii. “Many men come to grief from having too much confidence in their own inability.” (unknown)

ix. “People who make the best of things seldom try to make them any better” (Jacob Braude (maybe?))

x. “Trying to make an impression usually ends up in making merely an impression of trying” (unknown)

xi. “Egotism is the one thing nobody will forgive in others, and which everybody forgives in himself.” (unknown)

xii. “It’s only a good person who can have a bad conscience.” (unknown)

xiii. “It’s as hard to admit that your enemy has many virtues as to admit that you have many faults.” (unknown)

xiv. “If you are willing to admit faults, you have one less fault to admit.” (unknown)

xv. “The man who puts a woman on a pedestal is in danger of getting kicked in the face.” (Cute. The only source I can find is page 20 of The Greeley Daily Tribune, September 24, 1974).

xvi. “Being a molecular biologist I get so tired of people saying “Why cant we cure cancer?” Cancer is not one thing and as shown in this article even one “type” of cancer has many variables. Also, tangentially, I hate when people say “This food is good for you because it prevents cancer.” I always respond with “What type of cancer and what does it do exactly?” They have no idea.” (katlassi, here)

April 20, 2012 Posted by | Books, Cancer/oncology, Quotes/aphorisms | Leave a comment

Query

I’m thinking about expanding my almost nonexistent boardgame collection. Any input would be greatly appreciated. Preferably the game I’m looking for should be:

i) A game that rational, intelligent people would have fun playing against each others more than just a few times.
ii) A game that can be played by 2 players. If it can also be played by three or four players – even better.
iii) There should be a low level of randomness involved. Games which do not involve the use of dice are strongly preferred to the alternative.
iv) Game complexity should be reasonably high. Minimum acceptable duration of a game is probably something like 30-40 minutes. That said, I’m not looking for a 5- or 10-hour game.
v) It’s a plus if the game makes use of (/supports the implementation of) multiple game theoretic elements; such as signalling, countersignalling, (/potentially unstable?) equilibrium strategies, and imperfect- and asymmetric information. It’s a plus if the risk profiles of the players actually matter for gameplay and it is a plus if the game allows/encourages players to play ‘mind-games’ with each other during the game. Even if the level of randomness should be low, it should not be a game that can be ‘solved’ analytically. Player interactions and -dynamics should be emphasized.
vi) An example of the kind of game I am looking for is Citadels. (Though you should not recommend this particular game, as I already know it’s awesome and I play it on a regular basis).
vii) ‘Knowledge games’ are not bad, but I’ve never seen one that fulfils the criteria above. If you can win the game by knowing that the answer is hypertrophication, it’s not the game I’m looking for.

If you can’t think of a specific game that fulfils the criteria but you can still think of a different kind of game which you enjoy playing, or a game that shares some of the characteristics but not others, you are free to tell me about it below in a comment, as long as you remember to make it clear that it may not be precisely what I’m searching for (please don’t leave the comment section completely empty or I’ll be disappointed!).

April 19, 2012 Posted by | Random stuff | 5 Comments

Anthropology lectures

I’ve mentioned John Hawks’ anthropology lectures on the twitter, but I don’t think I’ve blogged about them. As I know that some (most?) people who read the blog don’t read my tweets, I thought it would be a good idea to give you a heads up. Yesterday I had some time to myself, and I spent a few hours watching this stuff. The category ‘lectures‘ on his blog unfortunately at this point does not include all his lectures. Some of the missing ones on that list are: Milk (actually most of it is not about milk, but rather about the energy expenditure differences between the sexes and related stuff like gender dimorphism), Premolars, Ears, Eyes and Hemoglobin.

The format is not completely optimal yet. Sometimes when Hawks talks about a specific slide it can be hard to follow because you can’t see what he’s pointing at. When a student answers one of his questions along the way, most of the time it is impossible to hear what the student is saying (however Hawks often repeats the answer to the class, ameliorating this problem somewhat). But these things aren’t a big deal, and I love the fact that lectures such as these are available for free online (which I’ve also told Hawks directly – the mail he quotes here was from me). If you’re interested, go have a look.

April 15, 2012 Posted by | Anthropology, Lectures | Leave a comment

Most people do not understand music?

Well, it depends on how you define ‘music’ (see also my comments below), but either way… From lesswrong:

Comment by Will_Newsome: “‘Aren’t there people who can hear sounds but not music?’

FWIW I’ve read a study that says about 50% of people can’t tell the difference between a major and a minor chord even when you label them happy/sad. [ETA: Happy/sad isn’t the relevant dimension, see the replies to this comment.] I have no idea how probable that is, but if true it would imply that half of the American population basically can’t hear music.”

[…]

Comment by army1987:

http://languagelog.ldc.upenn.edu/nll/?p=2074

It shocked the hell out of me, too.”

The stuff in army1987’s link I found frankly incredible and I’ll probably do a bit of googling later on to see what pops up. It seems that whereas commenters to the article do not generally seem to have problems with distinguishing the isolated chords, quite a few of them do have significant problems with the sequence in the post. I’m flabbergasted that anyone would have any problems with either of the examples.

Knowing this will probably radically change how I think about e.g. giving concerts to ‘normal people’. Before I’ve basically assumed that people heard what I heard, more or less, when I played something. But if people have problems with stuff as simple as the sequence in the link, I should really take people at their word when they tell me that they ‘do not understand this kind of music’. I’ve always thought such a statement was best translated: ‘I couldn’t tell Beethoven from Mozart (‘I mentioned those two names because they are the only ones I know…’) and I do not feel comfortable judging types of music I don’t know very well.’ (or something along those lines) But maybe a better way to translate it would be: ‘I can’t hear what’s going on.’ People have quite a few times in the past told me that I shouldn’t worry about anything when playing for them because they wouldn’t be able to tell if I made a mistake or not anyway. I’ve always assumed they were just being nice and that of course they would be able to tell if I made a mistake; I’ve never seriously considered the possibility that some of them might actually have told me the truth.

They – including perhaps some of the readers of this blog (go have a look at the link if you’re curious) – really don’t know what they are missing out on. I framed the post title the way I did because it in my mind requires a lot more than just being able to distinguish notes to actually understand in any meaningful way at least most of the music I prefer to listen to. Learning to play (badly) has given me a much greater understanding of just how complex some music really is, how nuanced and detailed it is when you take that closer look you need to take to get to the bottom of it; and I’m well aware that ‘even someone like me’ will miss some details along the way. People much better than me do that as well.

Also, this makes it a little easier for me to understand how stuff like pop music ever got, well, popular. It has always been somewhat hard for me to explain the musical preferences of ‘the majority’ in a satisfactory way, and I’ve usually just used some implicit explanation involving ‘preferences…’ (which did not really explain much). Of course there are still a huge number of variables at play here, but it never really occured to me that part of the explanation for the diverging preferences might be that what I hear with my ears might not be what a lot of other people hear.

April 13, 2012 Posted by | Biology, Music | 1 Comment

Education at a glance 2009: OECD Indicators

I thought about just giving you the link, but I guess I should probably post a bit of data here as well. There’s a lot more stuff at the link. Please refrain from asking me questions about the assumptions underlying these estimates in the comments; if you care enough to ask about that kind of stuff, then you also care enough to click the link and figure out what’s going on yourself.

April 11, 2012 Posted by | Data, Demographics, education | Leave a comment

The Neuropathology of Alcohol-Related Brain Damage

“Excessive alcohol use can cause structural and functional abnormalities of the brain and this has significant health, social and economic implications for most countries in the world. Even heavy social drinkers who have no specific neurological or hepatic problems show signs of regional brain damage and cognitive dysfunction. Changes are more severe and other brain regions are damaged in patients who have additional vitamin B1 (thiamine) deficiency (Wernicke–Korsakoff syndrome). Quantitative studies and improvements in neuroimaging have contributed significantly to the documentation of these changes but mechanisms underlying the damage are not understood.”

From the abstract of this paper. Some more stuff from the paper:

“It has long been accepted that excessive alcohol use can cause structural and functional abnormalities of the brain and other organs (Courville, 1955; Victor et al., 1959; Dreyfus and Victor, 1961). In the brain, this has been demonstrated clinically, with imaging techniques and pathologically. Many alcoholics can also develop cirrhosis of the liver that can impact on brain structure and function and others develop nutritional deficiency states (vitamin B1 deficiency) that can cause severe brain damage and dysfunction. These latter two groups of alcoholic cases are often defined as ‘complicated alcoholics’ to differentiate them from those who do not have liver disease or nutritional deficiency states (uncomplicated alcoholics). Nevertheless, ‘uncomplicated alcoholics’ who are cognitively impaired have abnormalities (Pfefferbaum et al., 1997). The risks of ‘moderate’ alcohol consumption are more difficult to assess. Ding and colleagues showed that the more alcohol consumed, the larger the cerebrospinal fluid-filled spaces of the brain became (Ding et al., 2004). This data correspond with a neuropathological study that showed an increase in the cerebrospinal fluid-filled spaces covering the brain (pericerebral space) in men drinking more than eight standard drinks per day and a similar distinctive trend in those drinking five to eight standard drinks per day (Harper et al., 1988). […]

The first quantitative neuropathological study on brain weights in alcoholics (Harper and Blumbergs, 1982) was inspired by the various reports of ‘brain shrinkage’ seen on CT scans in alcoholics (Cala et al., 1978; Ron et al., 1980). Alcoholics have a reduced brain weight compared to controls and the degree of brain atrophy has been shown to correlate with the rate and amount of alcohol consumed over a lifetime (Harding et al., 1996). […]

As noted above, the mechanism for alcoholism-related white matter loss, restoration with alcohol abstinence and disruption of micro structural integrity still remains unclear but probably involves changes in both myelination and axonal integrity. This has been inferred from in vivo human and experimental MR diffusion tensor imaging studies (Pfefferbaum et al., 2006b, 2007) and may explain why tissue volume recovery appears incomplete with abstinence. Thus, alcoholic brain pathology may have two components, one reflecting permanent change and one a transient change. Regarding permanent effects, alcohol-related neuronal loss has been documented in specific regions of the cerebral cortex (superior frontal association cortex), hypothalamus and cerebellum (Harper, 1998). Such loss will result in axonal (Wallerian) degeneration and a permanent reduction in white matter volume. Structural changes in myelin, however, could explain the reversible white matter shrinkage that has been documented with serial MRI studies following periods of abstinence from alcohol (Shear et al., 1994; Pfefferbaum et al., 1995; Gazdzinski et al., 2005). […]

Analysis of the types of neurons lost from the frontal cortex revealed that they were the larger ones with a somal area >90 μm (Harper and Kril, 1989). This population of neurons is also more vulnerable in both Alzheimer’s disease (Terry et al., 1981) and normal aging (Terry and Hansen, 1987). There does not appear to be any link between alcohol-related brain damage and Alzheimer’s disease (Morikawa et al., 1999), although there is some work that suggests a relationship between alcohol and aging (Harper et al., 1998a).”

April 9, 2012 Posted by | alcohol, Medicine, Neurology, Studies | Leave a comment

The planning fallacy

Abstract

The planning fallacy refers to a prediction phenomenon, all too familiar to many, wherein people underestimate the time it will take to complete a future task, despite knowledge that previous tasks have generally taken longer than planned. In this chapter, we review theory and research on the planning fallacy, with an emphasis on a programmatic series of investigations that we have conducted on this topic. We first outline a definition of the planning fallacy, explicate controversies and complexities surrounding its definition, and summarize empirical research documenting the scope and generality of the phenomenon. We then explore the origins of the planning fallacy, beginning with the classic inside–outside cognitive model developed by Kahneman and Tversky [Kahneman, D., & Tversky, A. (1979). Intuitive prediction: biases and corrective procedures. TIMS Studies in Management Science, 12, 313–327]. Finally, we develop an extended inside–outside model that integrates empirical research examining cognitive, motivational, social, and behavioral processes underlying the planning fallacy.”

From The Planning Fallacy: Cognitive, Motivational, and Social Origins by Buehler et al. A few snips of interest from the paper:

[…]

“3.1. The inside versus outside view
Given the prevalence of optimistic predictions, and ample empirical evidence of the planning fallacy, we now turn to examining the psychological mechanisms that underlie people’s optimistic forecasts. In particular, how do people segregate their general theories about their predictions (i.e., that they are usually unrealistically optimistic) from their specific expectations for an upcoming task? Kahneman and Tversky (1979) explained the prediction failure of the curriculum development team through the inside versus outside analysis of the planning fallacy. This analysis builds upon a perceptual metaphor of how people view a planned project. In the curriculum development example, the group of authors focused on the specific qualities of the current task, and seemed to look inside their representation of the developing project to assess its difficulty. The group of authors failed, however, to look outside of the specific project to evaluate the relevant distribution of comparable projects. Even when they asked for information about the outside viewpoint, they neglected to incorporate it in their predictions or even to moderate their confidence. An inside or internal view of a task focuses on singular information: specific aspects of the target task that might lead to longer or shorter completion times. An outside or external view of the task focuses on distributional information: how the current task fits into the set of related tasks. Thus, the two general approaches to prediction differ primarily in whether individuals treat the target task as a unique case or as an instance of a category or ensemble of similar problems. […]

We suggest that people often make attributions that diminish the relevance of past experiences to their current task. People are probably most inclined to deny the significance of their personal history when they dislike its implications (e.g., that a project will take longer than they hope). If they are reminded of a past episode that could challenge their optimistic plans, they may invoke attributions that render the experience uninformative for the present forecast. This analysis is consistent with evidence that individuals are inclined to explain away negative personal outcomes (for reviews, see Miller & Ross, 1975; Taylor & Brown, 1988). People’s use of others’ experiences are presumably restricted by the same two factors: a focus on the future reduces the salience of others’ experiences, and the tendency to attribute others’ outcomes to their dispositions (Gilbert & Malone, 1995) limits the inferential value of others’ experiences. Furthermore, our understanding of other people’s experiences is typically associated with uncertainty about what actually happened; consequently, we can readily cast doubt on the generalizability of those experiences. To quote Douglas Adams, ‘‘Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.’’ (Adams & Carwardine, 1991, p. 116) In sum, we note three particular impediments to using the outside perspective in estimating task completion times: the forward nature of prediction which elicits a focus on future scenarios, the elusive definition of ‘‘similar’’ experiences, and attributional processes that diminish the relevance of the past to the present.

3.3. Optimistic plans

People’s completion estimates are likely to be overly optimistic if their forecasts are based exclusively on plan-based, future scenarios. A problem with the scenario approach is that people generally fail to appreciate the vast number of ways in which the future may unfold (Arkes et al., 1988; Fischhoff et al., 1978; Hoch, 1985; Shaklee & Fischhoff, 1982). For instance, expert auto mechanics typically consider only a small subset of the possible things that can go wrong with a car, and hence underestimate the probability of a breakdown (Fischhoff et al., 1978). Similarly, when individuals imagine the future, they often fail to entertain alternatives to their favored scenario and do not consider the implications of the uncertainty inherent in every detail of a constructed scenario (Griffin et al., 1990; Hoch, 1985). When individuals are asked to predict based on ‘‘best guess’’ scenarios, their forecasts are generally indistinguishable from those generated by ‘‘best-case’’ scenarios (Griffin et al., 1990; Newby-Clark et al., 2000). The act of scenario construction itself may lead people to exaggerate the likelihood of the scenario unfolding as envisioned. Individuals instructed to imagine hypothetical outcomes for events ranging from football games to presidential elections subsequently regard these imagined events as more likely (for reviews, see Gregory & Duran, 2001; Koehler, 1991). Focusing on the target event (the successful completion of a set of plans) may lead a predictor to ignore or underweight the chances that some other event will occur. Even when a particular scenario is relatively probable, a priori, chance will still usually favor the whole set of possible alternative events because there are so many (Dawes, 1988; Kahneman & Lovallo, 1993).”

The paper has a lot more stuff and details.

April 7, 2012 Posted by | Psychology | 1 Comment

Wikipedia articles of interest

1. Trophic level.

“The trophic level of an organism is the position it occupies in a food chain. The word trophic derives from the Greek τροφή (trophē) referring to food or feeding. A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves. The number of steps an organism is from the start of the chain is a measure of its trophic level. Food chains start at trophic level 1 with primary producers such as plants, move to herbivores at level 2, predators at level 3 and typically finish with carnivores or apex predators at level 4 or 5. The path along the chain can form a one-way flow, or a food “web.” Ecological communities with higher biodiversity form more complex trophic paths. […]

The three basic ways organisms get food are as producers, consumers and decomposers.

*Producers (autotrophs) are typically plants or algae. Plants and algae do not usually eat other organisms, but pull nutrients from the soil or the ocean and manufacture their own food using photosynthesis. For this reason, they are called primary producers. In this way, it is energy from the sun that usually powers the base of the food chain.[1] An exception occurs in deep-sea hydrothermal ecosystems, where there is no sunlight. Here primary producers manufacture food through a process called chemosynthesis.[2]

*Consumers (heterotrophs) are animals which cannot manufacture their own food and need to consume other organisms. Animal that eat primary producers (like plants) are called herbivores. Animals that eat other animals are called carnivores, and animals that eat both plant and other animals are called omnivores.

*Decomposers (detritivores) break down dead plant and animal material and wastes and release it again as energy and nutrients into the ecosystem for recycling. Decomposers, such as bacteria and fungi (mushrooms), feed on waste and dead matter, converting it into inorganic chemicals that can be recycled as mineral nutrients for plants to use again.”

2. Charles de Gaulle.

3. Pareto distribution. You need to know a bit of statistics to make sense of this article.

4. Red Barn Murder.

“The Red Barn Murder was a notorious murder committed in Polstead, Suffolk, England, in 1827. A young woman, Maria Marten, was shot dead by her lover, William Corder. The two had arranged to meet at the Red Barn, a local landmark, before eloping to Ipswich. Maria was never heard from again. Corder fled the scene and although he sent Marten’s family letters claiming she was in good health, her body was later discovered buried in the barn after her stepmother spoke of having dreamt about the murder.

Corder was tracked down in London, where he had married and started a new life. He was brought back to Suffolk, and after a well-publicised trial, found guilty of murder. He was hanged in Bury St Edmunds in 1828; a huge crowd witnessed Corder’s execution. The story provoked numerous articles in the newspapers, and songs and plays. The village where the crime had taken place became a tourist attraction and the barn was stripped by souvenir hunters.”

5. SN 1987A. A little knowledge makes everything a little cooler, so of course I had to link to this after reading this awesome abstruse goose comic.

6. Structural history of the Roman military.

“The structural history of the Roman military concerns the major transformations in the organization and constitution of ancient Rome’s armed forces, “the most effective and long-lived military institution known to history.”[1] From its origins around 800 BC to its final dissolution in AD 476 with the demise of the Western Roman Empire, Rome’s military organization underwent substantial structural change. At the highest level of structure, the forces were split into the Roman army and the Roman navy, although these two branches were less distinct than in many modern national defense forces. Within the top levels of both army and navy, structural changes occurred as a result of both positive military reform and organic structural evolution. These changes can be divided into four distinct phases.

Phase I
*The army was derived from obligatory annual military service levied on the citizenry, as part of their duty to the state. During this period, the Roman army would wage seasonal campaigns against largely local adversaries.

Phase II
*As the extent of the territories falling under Roman control expanded and the size of the forces increased, the soldiery gradually became salaried professionals. As a consequence, military service at the lower (non-salaried) levels became progressively longer-term. Roman military units of the period were largely homogeneous and highly regulated. The army consisted of units of citizen infantry known as legions (Latin: legiones) as well as non-legionary allied troops known as auxilia. The latter were most commonly called upon to provide light infantry, logistical, or cavalry support.

Phase III
*At the height of the Roman Empire’s power, forces were tasked with manning and securing the borders of the vast provinces which had been brought under Roman control. Serious strategic threats were less common in this period and emphasis was placed on preserving gained territory. The army underwent changes in response to these new needs and became more dependent on fixed garrisons than on march-camps and continuous field operations.

Phase IV
*As Rome began to struggle to keep control over its sprawling territories, military service continued to be salaried and professional for Rome’s regular troops. However, the trend of employing allied or mercenary elements was expanded to such an extent that, these troops came to represent a substantial proportion of the armed forces. At the same time, the uniformity of structure found in Rome’s earlier military disappeared. Soldiery of the era ranged from lightly armed mounted archers to heavy infantry, in regiments of varying size and quality. This was accompanied by a trend in the late empire of an increasing predominance of cavalry rather than infantry troops, as well as a requirement for more mobile operations.” (the (featured) article has much more + plenty of links)

7. Megalodon.

“The megalodon (play /ˈmɛɡələdɒn/ MEG-ə-lə-don; meaning “big tooth”, from Greek μέγας (mega, “big”) and ὀδούς (odon, “tooth”)) is an extinct species of shark that lived roughly from 28 to 1.5 million years ago, during the Cenozoic Era (late Oligocene to early Pleistocene).

The taxonomic assignment of C. megalodon has been debated for nearly a century, and is still under dispute with two major interpretations; Carcharodon megalodon (under family Lamnidae) or Carcharocles megalodon (under family Otodontidae).[1] Consequently, the scientific name of this species has been commonly abbreviated to C. megalodon in literature.

C. megalodon is regarded as one of the largest and most powerful predators in vertebrate history.[2] C. megalodon likely had a profound impact on structuring of the marine communities. Fossil remains indicate that this giant shark reached a total length (TL) of more than 16 metres (52 ft),[1] and also affirm that it had a cosmopolitan distribution.[1] Scientists suggest that C. megalodon looked like a stockier version of the great white shark, Carcharodon carcharias, in life. […]

Somewhat related: In case you guys haven’t already heard about this, the remains of a huge feathered dinosaur was found in China recently. If you’re curious, you can read more here or here.

April 7, 2012 Posted by | Astronomy, Biology, Ecology, History, Paleontology, Statistics, Wikipedia | Leave a comment

The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems

“The impact of fishing on chondrichthyan stocks around the world is currently the focus of considerable international concern. Most chondrichthyan populations are of low productivity relative to teleost fishes, a consequence of their different life-history strategies. This is reflected in the poor record of sustainability of target shark fisheries.
Most sharks and some batoids are predators at, or near, the top of marine food webs. The effects of fishing are examined at the single-species level and through trophic interactions. We summarize the status of chondrichthyan fisheries from around the world. Some 50% of the estimated global catch of chondrichthyans is taken as by-catch, does not appear in official fishery statistics, and is almost totally unmanaged. When taken as by-catch, they are often subjected to high fishing mortality directed at teleost target species. Consequently, some skates, sawfish, and deep-water dogfish have been virtually extirpated from large regions. Some chondrichthyans are more resilient to fishing and we examine predictions on the vulnerability of different species based on their life-history and population parameters. At the species level, fishing may alter size structure and population parameters in response to changes in species abundance. We review the evidence for such density-dependent change. Fishing can affect trophic interactions and we examine cases of apparent species replacement and shifts in community composition. Sharks and rays learn to associate trawlers with food and feeding on discards may increase their populations.”

From the abstract of the study, which I found very interesting. Here’s some more stuff from the paper:

“Large-scale exploitation has led to changes in fish community structure. Fishers tend to remove the largest species first and then work their way down the food chain catching smaller species (Pauly et al., 1998). Consequently, changes in species composition of fished communities may be expected, with small, fastergrowing, and earlier-maturing species predominating. Small species may also be less desirable on the market, and may therefore be subjected to lower fishing mortality (Jennings and Kaiser, 1998; Jennings et al., 1999b). Within the chondrichthyans, the examples for skates discussed above reveal a broadly similar pattern. Similar patterns have also been reported in shark communities: as larger sharks were depleted smaller species proliferated (van der Elst, 1979). The general paradigm is that larger species decline while smaller species predominate.
There have also been declines in diversity associated with increasing fishing pressures, particularly in large predatory taxa (Jennings and Kaiser, 1998). Chondrichthyans tend to be high in the food web (Cortes, 1999) and, due to their greater vulnerability (relative to teleosts), are likely to be the first to decline from fishing. Rogers et al. (1999) suggested that fishing, through the differential vulnerability of elasmobranchs relative to teleosts, is responsible for major variations in fish diversity in the North-east Atlantic. […]

Discards from fisheries affect the amount of food available to scavengers and thus may be expected to have an effect on certain components of the ecosystem. Although some studies conclude that Australian prawn trawling had few significant, long-term impacts (Kennelly, 1995), about 95% of the by-catch in the Northern Prawn fishery is discarded, and most of it is dead (Wassenberg and Hill, 1989; Hill and Wassenberg, 1990). About half of the discards float and are scavenged by birds, dolphins, and sharks. The other half sinks and is preyed upon by sharks in mid-water and teleosts, sharks, and crustaceans on the bottom. […]

The predictions of the Venezuelan shelf ecosystem model under a mixed control assumption show that shark depletion could lead to strong and unforeseen changes in the abundances of many species (Fig. 4). According to the model, these changes would be permanent as long as shark populations remain depressed. Surprisingly, not all species whose abundances increased greatly are major prey of sharks. In fact, the species undergoing the greatest relative increases in abundance (croakers, snappers/groupers, grunts, catfish, and other demersals) are all minor components in the diet of the small triakid sharks, suggesting that shark depletion propagates through the food web in a complex way. Some changes are virtually demographic explosions of up to two and a half times the original biomass (i.e. croakers). Conversely, two of the major prey items of the sharks did not increase much in abundance; they even decreased (carangids and small pelagics). Squid and benthic producers, two groups not part of the diet, suffered abundance decreases of about 10% and 15%, respectively. Clearly, the outcomes are not as predictable as one might expect. […]

Conclusions
Chondrichthyans, by nature of their K-selected lifehistory strategies and high position in trophic food webs, are more likely to be affected by intense fishing activity than most teleosts. The group may in fact be indicators of fishing pressure. There is sufficient evidence from the history of fisheries around the world, both targeting these fishes and taking them as by-catch, of major declines in population size. For some groups, particularly certain skate species and sawfishes, there is mounting evidence suggesting that local if not global extinction is a distinct possibility. This problem is especially acute for species with restricted distributions. The massive and uncontrolled catch of chondrichthyans in the Indo-West Pacific, coupled with the higher diversity and rates of endemism in this region, are cause for major concern. There is increasing evidence that indirect effects of fishing are affecting the composition and diversity of chondrichthyan and total fish assemblages through trophic interactions. Differential vulnerability to fishing exists among sharks and rays and large, late maturing species appear to be most vulnerable. This has caused changes in the community through competitive release, although there is little evidence for species replacement. There is good evidence that selective fishing mortality can lead to changes in growth and juvenile survival for both sharks and batoids, leading to changes in population dynamics. However, the effects of removing large numbers of these top predators on the marine ecosystem are still largely unknown. Attention needs to be focused on this poorly studied group of fishes, particularly in the ecosystem context in terms of understanding trophic interactions.”

April 4, 2012 Posted by | Biology, Ecology, Evolutionary biology, Studies, Zoology | Leave a comment