July 17, 2009
09:23 AM
615 views

Junior doctors pressed into taking HIV tests

by Helen Jaques in In Sickness and In Health

Junior doctors are undergoing HIV tests as part of pre-employment occupational health checks without being made aware that such testing is not mandatory, according to research published in the Journal of Medical Ethics. Many junior doctors interviewed by Lee Salkeld and colleagues held the misperception that HIV testing was compulsory and felt unable to decline the test. In [...]... Read more »

Salkeld, L., McGeehan, S., Chaudhuri, E., & Kerslake, I. (2009) HIV testing of junior doctors: exploring their experiences, perspectives and accounts. Journal of Medical Ethics, 35(7), 402-406. DOI: 10.1136/jme.2008.027052

July 17, 2009
09:18 AM
886 views

Friday Picture: Have your coral and eat it, too?

by Peter Etnoyer in Deep Sea News

People accept the idea of echinoderm predation on shallow reef building corals. The voracious Crown of Thorns seastar Acanthaster planci is a familiar coral antagonist on the Great Barrier Reef, part of a natural process that may or may not be amplified by anthropogenic disturbance. Asteroid predation on deep-sea corals is more difficult to demonstrate. [...]... Read more »

Etnoyer, P. (2008) A new species of Isidella bamboo coral (Octocorallia: Alcyonacea: Isididae) from northeast Pacific Seamounts. Proceedings of the Biological Society of Washington, 121(4), 541-553. DOI: 10.2988/08-16.1

Mosher, C., & Watling, L. (2009) Partners for life: a brittle star and its octocoral host. Marine Ecology Progress Series. DOI: 10.3354/meps08113

July 17, 2009
09:00 AM
1,098 views

Guest post: Neil Walker on the curious case of the schizophrenia GWAS

by dgmacarthur in Genetic Future

Purcell et al. (2009). Common polygenic variation contributes to risk of schizophrenia and bipolar disorder Nature DOI: 10.1038/nature08185Neil Walker has been doing a spectacular job of serving up useful information in the comments recently, so I asked him to write the first ever guest post on Genetic Future - something that (as I will be announcing shortly) I intend to do fairly regularly over the next couple of months.The topic is a paper that has created a rather perplexed buzz recently in the complex disease genetics community: the genome-wide association study (GWAS) for schizophrenia published in Nature last week. This paper takes a novel and (at first glance) rather alarming approach to exploring the genetic basis of this complex disease, so I asked Neil to provide some insight into what he thought about the approach used in this paper and what it means for complex disease genetics.Without further comment, I present Neil's post: Read the rest of this post... | Read the comments on this post...... Read more »

Purcell, S., Wray, N., Stone, J., Visscher, P., O'Donovan, M., Sullivan, P., Sklar, P., Purcell (Leader), S., Stone, J., Sullivan, P.... (2009) Common polygenic variation contributes to risk of schizophrenia and bipolar disorder. Nature. DOI: 10.1038/nature08185

July 17, 2009
09:00 AM
1,194 views

Mechanisms of Drug Tolerance

by Shaheen Lakhan in Brain Blogger

New data emerging from the investigation of the death of Michael Jackson reveal that the iconic pop star was taking very high doses of sedative medications during the course of his career. At the time of his death, it was reported that he was taking at least ten tablets of the powerful sedative Xanax every [...]... Read more »

Christie, M. (2008) Cellular neuroadaptations to chronic opioids: tolerance, withdrawal and addiction. British Journal of Pharmacology, 154(2), 384-396. DOI: 10.1038/bjp.2008.100

Bateson, A. (2002) Basic Pharmacologic Mechanisms Involved in Benzodiazepine Tolerance and Withdrawal. Current Pharmaceutical Design, 8(1), 5-21. DOI: 10.2174/1381612023396681

Hutchinson, M. (1996) The behavioural and neuronal effects of the chronic administration of benzodiazepine anxiolytic and hypnotic drugs. Progress in Neurobiology, 49(1), 73-97. DOI: 10.1016/0301-0082(96)00011-1

Medicine

July 17, 2009
08:15 AM
735 views

What does this anthropologist think about hormonal birth control? Part III

by Kate Clancy in Laboratory for Evolutionary Endocrinology

In parts I and II of this series, I discussed the basic no-nos around contraception, the reason some advocate its continuous use, and what constitutes a normal menstrual cycle. Today, I'll explain a bit about population variation in reproductive function, and how it may relate to the conversation.Population variationBoth the efficacy of hormonal contraception and its non-contraceptive benefits are reduced if women do not take their prescriptions properly, and there are many reasons women do this: poor education regarding what constitutes ‘perfect use,’ ambivalence about their choice of contraception, or dissatisfaction regarding side effects. Baerwald and colleagues found different degrees of suppressed ovulation depending on when contraceptives were started; if hormonal contraception was initiated at or before ovarian follicles had reached 10mm, suppression occurred in all cases, but became increasingly less likely as follicles increased in size (Baerwald et al. 2006). One of the methods of initiating hormonal contraceptives involves the idea of a ‘Sunday Start’ where women start taking the medication the first Sunday after their last menses, rather than on the first day of menses. The reasoning is that it is easier to keep track of pills (or patches or rings) when one starts each week on a Sunday rather than on whatever day menses happens to begin. Unfortunately, significant follicular growth can occur between menses and the start of the contraception, depending on the individual and the day menses began. This can mean a woman can think she is protected from pregnancy for that cycle, but has ovulated and thus at a much greater risk for unwanted pregnancy. If a woman stops and starts – due to difficulties obtaining her prescription, traveling, or dissatisfaction with the brand of contraceptive she chooses – she may have many ovulatory cycles, or at the least many cycles where her follicles are growing and regressing. My worry is that this could lead to polycystic ovaries or even mutations during tissue remodeling that could lead to ovarian cancer (this is a hypothesis, not an observation or statement of empirical evidence).Other reasons a woman may not stay on hormonal contraception and thus may not have ‘perfect use’ is that her normal range of variation in endogenous hormones is different from the American norm. Women from developing countries tend to have lower circulating levels of reproductive hormones (for examples directly related to contraception, see Bentley 1996; Ellison 1990; Vitzthum et al. 2004); this means their responsiveness to the exogenous hormones of contraceptives will be different, just like with overweight American women but at the other end of the spectrum. Bentley (1996) reports significant interpopulation variation in pharmacokinetic properties of hormonal contraceptives; this means that different women have different physiological responses to hormones, even when taking the same dose. She also reviewed the literature regarding interpopulation variation in side effects experienced by women on hormonal contraception (Bentley 1996). Vitzthum and colleagues (2001) report shorter duration of menses for samples of Bolivian versus Chicago women, and significantly lower endogenous hormone concentrations in Bolivian versus Chicago women (Vitzthum et al. 2004). The penultimate paragraph of the 2004 article is the most telling:“The present study also reaffirms the conclusion of others that hormonal contraceptive dosages designed for U.S. women and other industrialized countries may be excessively high for women in developing countries, resulting in severe side-effects leading to discontinuation and, potentially, unplanned pregnancy. We have often heard Bolivian women and health workers express concern about negative experiences with hormonal contraceptives. Contrary to arguments that noncompliance is more a matter of education than biology, these data succinctly support the reports of these women that negative sequelae of hormonal contraceptives are more than an imagined problem.”Thus we have Bentley’s review of variation in effects on contraception, several decades of literature on population variation in ovarian function via ecology, and anecdotal evidence from the mouths of women from developing countries; put together, they tell a story about a broad spectrum of women who may respond differently to hormonal contraceptives. On Monday I'll cover whether hormonal contraceptives create any behavior or cognition changes in those who take them.ReferencesBaerwald A, Olatunbosun O, & Pierson R (2006). Effects of oral contraceptives administered at defined stages of ovarian follicular development Fertility and Sterility, 86 (1), 27-35Bentley GR. 1996. Evidence for interpopulation variation in normal ovarian function and consequences for hormonal contraception. In: Rosetta LaM-T, C.G.N., editor. Variability in human fertility. Cambridge, UK: Cambridge University Press. p 46-65.Ellison PT (1990). Human ovarian function and reproductive ecology: new hypotheses American Anthropologist, 94 (2), 933-952Vitzthum VJ, Spielvogel H, Caceres E, & Miller A (2001). Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss Contraception, 64, 319-325Vitzthum VJ, Spielvogel H, & Thornburg J (2004). Interpopulational differences in progesterone levels during conception and implantation in humans Proceedings of the National Academy of Sciences, 101 (6), 1443-1448This post was written by Kathryn Clancy for the Laboratory for Evolutionary Endocrinology Blog. Except as noted, it is (C)Kathryn Clancy and licensed under a Creative Commons License. The opinions on this blog are the opinions of the blog author only, not the author's employer or colleagues.... Read more »

Baerwald A, Olatunbosun O, & Pierson R. (2006) Effects of oral contraceptives administered at defined stages of ovarian follicular development. Fertility and Sterility, 86(1), 27-35.

Ellison PT. (1990) Human ovarian function and reproductive ecology: new hypotheses. American Anthropologist, 94(2), 933-952.

Vitzthum VJ, Spielvogel H, Caceres E, & Miller A. (2001) Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss. Contraception, 319-325.

Vitzthum VJ, Spielvogel H, & Thornburg J. (2004) Interpopulational differences in progesterone levels during conception and implantation in humans. Proceedings of the National Academy of Sciences, 101(6), 1443-1448.

July 17, 2009
08:05 AM
1,029 views

Gaps in climate knowledge! Oh no!

by James Hrynyshyn in Class M

If predicting climate trends was as easy as predicting the reaction of global warming pseudoskeptics there wouldn't be any deniers left. When I came across a new study in Nature Geoscience on the cause of the massive shift in the climate 55 million years ago, my first reaction was, "How long will it take before someone completely misrepresents this paper as evidence that undermines anthropogenic global warming?"

Not long. See here, here and here, if you have the time. Read the rest of this post... | Read the comments on this post...... Read more »

Zeebe, R., Zachos, J., & Dickens, G. (2009) Carbon dioxide forcing alone insufficient to explain Palaeocene–Eocene Thermal Maximum warming. Nature Geoscience. DOI: 10.1038/ngeo578

Geosciences

July 17, 2009
08:00 AM
1,498 views

The Scincus that swims through sand like a snake

by Zen Faulkes in NeuroDojo

In old Disney comics, Scrooge McDuck would often be shown swimming in his money bin, diving through the coins like an exuberant dolphin. Leading many young minds to wonder, “How does he do that?” Coins don’t move like water; they’re arguably closer to something like dry sand.A new paper shows that one lizard may not be able to get through McDuck’s nine cubic acres of money, but it comes a lot closer than anything else we know about so far. Scincus scincus is a cute little lizard a few winches long, whose common name, “sandfish,” tells you a lot about its behaviour. These lizards dive through sand like Unca Scrooge dives through silver dollars. Previously, people had suspected they paddled though the sand using their legs, much like some fish might use their pectoral fins in addition to their trunk. The problem with testing an hypothesis like this is that sand has this irritating property of being opaque – a problem I had significant personal experience with, I might add. I solved it using wires and recording from muscles.Maladen and colleagues went to high speed X-ray videography. I suspect that they probably spent a long time trying to find a combination of materials with the right combination of transparencies to X-rays, but they did it. And they found that the sandfish might better be described as a sand eel. The swimming that these lizards did (rather fast, about 10 cm per second) was entirely driven by the trunk. The legs were simply held in position and didn’t play a part after the animal got under the sand. There are some fantastic movies of this in the supplemental material.From here, the paper looks into the physics of the situation. To be entirely honest, it’s fairly difficult stuff for me. When they write:It is remarkable that η does not change significantlyfor different φ...I have to take their word for the remarkable nature of those Greek letters. I am rather hoping that some physics blogger out there can walk through the granular materials math in this paper.Maladen and company end by noting that they have helped to show how organisms can exploit the alternately solid-like and fluid-like properties of sand to move through it. And this is indeed a substantial achievement, but what if you turn that around? If animals can do this, why haven’t more done so? To the best of my knowledge, no animals besides other lizards swim through sand like sandfish do. And I doubt that this is due to visibility problems; I think it is just that digging organisms are relatively rare.There is so much nice stuff in this paper that I might forgive them for citing a sand crab digging paper from the 1970s instead of more recent and more detailed articles.ReferenceRyan D. Maladen, Yang Ding, Chen Li, & Daniel I. Goldman (2009). Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard Science, 325 (5938), 314-318 DOI: 10.1126/science.1172490Sandfish photo by user thew...g's on Flickr. Used under Creative Commons license.... Read more »

Ryan D. Maladen, Yang Ding, Chen Li, & Daniel I. Goldman. (2009) Undulatory Swimming in Sand: Subsurface Locomotion of the Sandfish Lizard. Science, 325(5938), 314-318. DOI: 10.1126/science.1172490

July 17, 2009
07:33 AM
1,273 views

The mystery of the rotating seeds

by Katherine Porter in Galley Proofs

If you live in a temperate deciduous climate, you probably know what a maple tree is. And if you’ve been in a maple forest during spring or fall—or, really, any time of year—you’ve probably seen maple seeds. They look a bit like badminton birdies, only flattened: a heavy, solid "nut" at the bottom, with a single "wing" above. The wing helps the seed fly relatively long distances (for a plant)—up to a few kilometers in some cases. A maple seed. From http://commons.wikimedia.org/wiki/File:Maple-seed.jpg. Watching a maple seed fly is an interesting experience—they flutter and twist very rapidly. Because they twist and spin as they fall, scientists say they autorotate. In fact, they autorotate quite stably—a factor that allows the wind to carry them far from their parent trees. Maples aren't the only trees with autorotating seeds—hornbeams, for example, have similar winged seeds. In all of these seeds, the autorotation is thought to help create extra lift on the seed, enabling it to travel farther from the parent tree. (Rambling offspring are a benefit for plants, because plant seedlings compete with surrounding plants for soil nutrients, sunlight, and water. If they land too close to the parent tree, they end up competing with their own parents—which benefits neither parent nor offspring, and therefore is detrimental to the survival of the species.) Maple seeds and other autorotating seeds produce surprisingly large amounts of lift as they fall, considering how small and relatively slow they are. This is similar to the wings of many insects, which can produce a lot of lift from a relatively small surface area. Insect wings create this lift through the production of a leading edge vortex (LEV)—that is, a maelstrom of disrupted air along the edge of the seed that is "cutting through" the air as the seed falls. (Think of a wing—one edge of it is pushing through the air as it moves forward. The other edge trails along behind. The edge cutting through the air is the leading edge.) In the 12 June issue of Science, Lentink et al report results of an investigation into the motions of maple seeds as they fall. Because the LEVs generated by insect wings help the insects produce significant lift, the researchers reasoned that maple seeds might produce similar LEVs. Maple seeds are relatively small, and studying them while they fall can be challenging. This is especially true if one is interested in observing the flow of air over and around the seed as it falls. Therefore, as an initial test, Lentink et al built a scale model of a maple seed that was somewhat larger than a real seed. To make studying the movement of the air over the seed easier, they attached the model seed to a large arm inside a tank of mineral oil. It may not be immediately clear how putting a model seed in mineral oil can be used to study the flow of air around a real seed. It turns out that this works because air and mineral oil are both fluids—substances that can flow in response to stress (pressure). As it happens, all fluids behave pretty much the same way under specific kinds of stress, provided that their differences in viscosity (resistance to flow, or thickness) are taken into account. The main difference viscosity makes is in the force required to move through the fluid—as you know if you've ever tried to walk under water. The more viscous the fluid, the more force is required to push through it, and the more slowly it returns to its original position. This latter property is the reason that many fluid dynamics studies are performed in oil or water, rather than air: the higher viscosity of a liquid makes observing its flow paths much easier. The path the liquid follows around the object is the same as the path that air would follow, so the results of the study are easily transferred to air. Lentink et al used digital particle image velocimetry (DPIV) to make an image of the fluid flow around the model seed as it "fell" through the oil. DPIV is a technique that uses laser light, high-speed cameras, and computer integration to determine the velocity (speed and direction) of the fluid moving around an object in various locations. In DPIV, tiny particles are suspended in the fluid. During the experiment, as the fluid is moving, rapid flashes of laser light shine on the fluid, making the suspended particles visible for brief instances. A high-speed camera photographs the particles during each flash. The images are fed into a computer, which analyzes the locations of the particles during each instant. Because the computer knows the location of each particle at specific instances in time, it can calculate the velocity of each particle over time. Once the computer has calculated the velocities of the particles, it can create a three-dimensional image of how they move (and, by extension, how the fluid moves). Using DPIV, Lentink et al identified a very pronounced LEV along the model seed. To confirm that their model seed accurately represents real seeds, they placed real maple seeds in a vertical wind tunnel. They adjusted the wind speed in the tunnel so that it matched the air speed the seeds would experience as they fell. As a result, the seeds hovered in place, but still spun the same way they would if they were actually falling. They recorded the motions of the seeds as they rotated. They were also able to create images of the flow of air around the seeds. The experiments with the real seeds confirmed the results seen in the model studies: maple seeds do, indeed, produce significant LEVs as they fall. By comparing the maple seeds to other plant seeds, Lentink et al showed that the rotation of the maple seeds, and the resulting development of the LEVs, allows maple seeds to fall more slowly than non-rotating seeds of a similar wing loading (wing loading is the ratio of seed weight to surface area). Therefore, maple trees (or hornbeam trees, or other trees with rotating seeds) can produce heavier seeds (which can contain more food for the embryonic tree), but those seeds can still travel far enough from the parent trees to avoid competition. Maple and hornbeam trees are not the only organisms to make use of the extra lift provided by LEVs, though. Hovering insects, bats, and possibly some birds also benefit from the production of LEVs along their wing edges. It makes me wonder whether "winged" marine organisms might generate similar vortices along their wings as they "fly" through the water. Lentink, D., Dickson, W., van Leeuwen, J., & Dickinson, M. (2009). Leading-Edge Vortices Elevate Lift of Autorotating Plant Seeds Science, 324 (5933), 1438-1440 DOI: 10.1126/science.1174196... Read more »

Lentink, D., Dickson, W., van Leeuwen, J., & Dickinson, M. (2009) Leading-Edge Vortices Elevate Lift of Autorotating Plant Seeds. Science, 324(5933), 1438-1440. DOI: 10.1126/science.1174196

July 17, 2009
07:20 AM
1,847 views

Baldwin and Bot Flies

by bug_girl in Bug Girl's Blog

Because, as busy as I am, I can always stop and bring you news of a celebrity-insect nexus.

I don’t watch much TV–and so I REALLY had no plans to watch “I’m a Celebrity, Get Me Out of Here!” (although if Rob Blagojevich had been on, that might have been worth it, just to see what [...]... Read more »

Catts, E. (1982) Biology of New World Bot Flies: Cuterebridae. Annual Review of Entomology, 27(1), 313-338. DOI: 10.1146/annurev.en.27.010182.001525

Marty, Francisco M., Whiteside, Kristen R. (2005) Myiasis Due to Dermatobia hominis (Human Botfly). New England Journal of Medicine, 352(23), 21. DOI: http://content.nejm.org/cgi/content/short/352/23/e21

July 17, 2009
07:17 AM
699 views

What does this anthropologist think about hormonal contraception? Part III

by Kate Clancy in Laboratory for Evolutionary Endocrinology

Part three of my ongoing series on hormonal contraception and reproductive function, from the perspective of anthropology.... Read more »

Baerwald A, Olatunbosun O, & Pierson R. (2006) Effects of oral contraceptives administered at defined stages of ovarian follicular development. Fertility and Sterility, 86(1), 27-35.

Ellison PT. (1990) Human ovarian function and reproductive ecology: new hypotheses. American Anthropologist, 94(2), 933-952.

Vitzthum VJ, Spielvogel H, Caceres E, & Miller A. (2001) Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss. Contraception, 319-325.

Vitzthum VJ, Spielvogel H, & Thornburg J. (2004) Interpopulational differences in progesterone levels during conception and implantation in humans. Proceedings of the National Academy of Sciences, 101(6), 1443-1448.

July 17, 2009
12:59 AM
1,106 views

Friday Weird Science: Refridgerator Mothers vs Refridgerator Kids

by Evil Monkey in Neurotopia

One of the great things about weird AND historical science is the great quotes that old-fashioned writing styles tend to produce. Today's quote, for example "information on the force effects of children". The force effects of children? When merely thrown? Or when using some sort of specialized device, such as a child-size trebuchet or slingshot?

(Kid sized!)

Well, no, this paper is not about forces of children when used as objects. It's about the forces of children used for doors. Refrigerator doors, actually. A study like this would probably never fly now, but heck, the world of child psychology was young. It was 1958.

Bain, Feagre, Wyly. "Behavior of young children under conditions simulating entrapment in refrigerators." Pediatrics, 1958.

Sci got this paper some time ago, and unfortunately, when she tried to go back online and get the pictures, was THWARTED. Grr. No pics. Too bad, some of them were incredibly 1950s. If anyone has a copy, pass it along? I can edit pics in! Read the rest of this post... | Read the comments on this post...... Read more »

Katherine Bain M.D., Marion L. Faegre B.A., and Robert S. Wyly B.S. (1958) BEHAVIOR OF YOUNG CHILDREN UNDER CONDITIONS SIMULATING ENTRAPMENT IN REFRIGERATORS . PEDIATRICS, 22(4), 628-647. DOI: http://pediatrics.aappublications.org/cgi/content/abstract/22/4/628

July 17, 2009
12:00 AM
1,480 views

Typocerus deceptus in Missouri

by Ted MacRae in Beetles in the Bush

Photographs and comments on the discovery of the rare longhorned beetle, Typocerus deceptus (Coleoptera: Cerambycidae) in Missouri.... Read more »

McDowell, W., & MacRae, T. (2008) First record of Typocerus deceptus Knull, 1929 (Coleoptera: Cerambycidae) in Missouri, with notes on additional species from the state. The Pan-Pacific Entomologist, 84(4), 341-343. DOI: 10.3956/2008-23.1

July 16, 2009
07:09 PM
1,058 views

Natural Resources & Armed Conflict

by Randy Borum in Science of Global Security & Armed Conflict

Natural resources can make conflicts more deadly. When gems or oil/gas production exist inside a conflict zone, more combat deaths tend to result. This finding comes from an analysis of 258 worldwide conflicts conducted by Paivi Lujala from the Norwegian University of Science and Technology.Lujala's research builds on earlier studies showing linking the presence of natural resources to the onset and likelihood of armed conflict in a given area. His analysis extends this knowledge by focusing on the impact of these resources on conflict severity. Severity was measured by the total number of combat deaths and the average rate of combat deaths (which he refers to as a measure of "intensity"). He also was able to compare effects inside vs outside of conflict zones within a given country, rather than just using the country as a single geographic unit.The study examined three commonly occurring natural resources: (1) gemstone mining; (2) Hydrocarbon (crude oil/natrual gas) production; and (3) illicit drug cultivation (cocoa, opium poppy, & cannabis). Results are interesting and some are a bit surprising.Think for a moment about which of these three resources - gems, hydrocarbons, or drugs - you would immediately associate with an increase in combat deaths. Here's a hint - Two of them are linked to an increase in deaths and one is associated with fewer deaths. OK - if you read the headline, you know the answer. Drug cultivation inside conflict zones is linked to fewer - yes, fewer - combat deaths and a lower battle death rate. Tony Addison and colleagues - in analyzing African conflicts - have suggested that this kind of effect may occur because combatants on both sides of a conflict spend some proportion of their time looting resources rather than just killing each other.Gems and hydrocarbons, on the other hand, significantly raised the risk of severity. Gemstone production inside the conflict zone basically doubled the the number of conflict fatalities . Similarly, when oil and gas production existed inside the zone, more than twice as many combat deaths occurred as when that production was absent. The effect was most pronounced in secessionist conflicts. A seemingly significant mechanism in both cases is that conflicts seem to go on longer when these resources are inside the conflict zone. Longer conflicts, of course, tend to produce more deaths.Drilling down further (no pun intended), though, oil and gas production was associated with lower severity (lower rate and fewer deaths) when it was present in the country/region, but existed outside the conflict zone. Perhaps this is because the resources are less accessible to rebel combatants, and they continue to provide a source of revenue for the government/military, which may then be able to invest more in quashing the rebellion and ending the conflict sooner (shortening the duration).Though not the focus of this particular study, a: couple of incidental severity predictors emerged and are worth noting:The comparative size/strength of state military and rebel forces affects severity. The death toll tends to be highest when both force sizes are more equal. When the rebel forces are notable weaker, the rate of overall combat deaths seems to be lower.Conflicts tended to be more severe when they:occurred during the Cold War periodwere fought in mountainous terrainwere fought in more populated countries andwere internationalized internal conflictsConflicts tended to be less severe in countries that were more democratic and ethnically heterogeneous.Lujala, P. (2008). Deadly Combat over Natural Resources: Gems, Petroleum, Drugs, and the Severity of Armed Civil Conflict Journal of Conflict Resolution, 53 (1), 50-71 DOI: 10.1177/0022002708327644... Read more »

Lujala, P. (2008) Deadly Combat over Natural Resources: Gems, Petroleum, Drugs, and the Severity of Armed Civil Conflict. Journal of Conflict Resolution, 53(1), 50-71. DOI: 10.1177/0022002708327644

July 16, 2009
06:02 PM
839 views

In search of moons of Venus

by Niall in we are all in the gutter

Venus still has no moons, not the most interesting start to an article, but I thought I may as well start this post by giving the ending away. Why? Partly because I get a strange kick out of spoiling your enjoyment of my own blog post (by the way, Murder on the Orient Express, turns out Poirot did it) and partly because I don't want to leave you under the misapprehension that this article is about the greatest discovery in modern Solar System astronomy, it's not. What it is about is this interesting paper which set out to find moons around Venus and (you may know this already) found none.... Read more »

Sheppard, S., & Trujillo, C. (2009) A survey for satellites of Venus. Icarus, 202(1), 12-16. DOI: 10.1016/j.icarus.2009.02.008

Astronomy

July 16, 2009
05:49 PM
1,046 views

Fiddler crabs - more than just cute to look at

by Christie Wilcox in Observations of a Nerd

I know everyone is going to jump at once to talk about this mind-blowing research by some of the greatest scientists that have ever been associated with ecology, and I hate just writing about papers that everyone will talk about anyhow, but I decided I still had to comment on this paper. It may very well be the most important paper of the year, even more influential and ground-breaking than Ida (though I wouldn't mention that to her directly). Of course, I'm talking about the newest paper published in Marine Biology's "Online First", Fiddler crab burrowing affects growth and production of the white mangrove (Laguncularia racemosa) in a restored Florida coastal marsh.This paper, written by three, top-notch biologists out of Eckerd College, explores the relationship between fiddler crab burrowing activity and the growth of young white mangroves through two different pathways. The first was a transect study, where mangrove growth variables were compared to burrow density and other plant density in a natural setting. The other used mesh cages to selectively reduce or allow burrowing activity around seedlings to study not only the growth differences but changes in the soil chemistry without the affects of other plants in the area. The sum results of the two were clear - fiddler crabs had a big impact. By digging burrows, they increased mangrove growth and proliferation by ~25%, and dramatically changed the soil chemistry. Their presence decreased salinity from over 44.2 to 32.4 and changed the oxidation potential, meaning they made the soils far more mangrove-friendly. While this might seem like a small study, it's actually quite important. Mangroves are some of the most important ecosystems in the tropics, providing food and shelter for many commercially and ecologically important species. And, most importantly, we've done a fantastic job of destroying them as humans have decided that treed, swampy coasts are far less pretty to build a house on than just pristine, bulldozed sand. Now, millions of dollars are being pumped into restoration efforts, and the more we know about how to cultivate and encourage the growth of these fickle but critical trees, the better.There might also be one other reason that I think this paper is so damned important... but I'll let you figure that one out for yourselves.Smith, N., Wilcox, C., & Lessmann, J. (2009). Fiddler crab burrowing affects growth and production of the white mangrove (Laguncularia racemosa) in a restored Florida coastal marsh Marine Biology DOI: 10.1007/s00227-009-1253-7... Read more »

Smith, N., Wilcox, C., & Lessmann, J. (2009) Fiddler crab burrowing affects growth and production of the white mangrove (Laguncularia racemosa) in a restored Florida coastal marsh. Marine Biology. DOI: 10.1007/s00227-009-1253-7

Biology

July 16, 2009
03:57 PM
1,566 views

Music participation doesn't appear to diminish performance in other schoolwork

by Dave Munger in Cognitive Daily

When school budgets are cut, programs in music and the arts are often the first to get axed. While this makes a certain amount of sense because music isn't always considered "essential" to education, recently in the U.S. we're starting to see another justification for cutting music out of schools. The No Child Left Behind Act demands that students meet a certain basic level of academic success, or a school's budget can be cut. "Extras" like music classes and recess only distract from the primary goals of learning English, math, science, and history, some say.

But does music participation actually cause students to do worse in the core academic subjects? Some studies have found the opposite, with kids' IQ scores improving after a year of music lessons. Other studies have found that students who participate in music tend to have higher grades and test scores in other subjects. This, however, is only a correlation--we don't know if music caused the improvement. Kids in music classes might be better in other subjects just because better students are more likely to take music classes. Maybe these kids would do even better in school if they weren't distracted by music.

Peter Miksza took a look at data from the 1988 National Educational Longitudinal Study to see if he could find stronger evidence of the impact of music on performance in school. He analyzed the records of 5,335 students who either participated in school music programs from 8th through 12th grade or did not participate at all (students who participated only part of the time were excluded from the analysis). Here are some of the results:

Read the rest of this post... | Read the comments on this post...... Read more »

Peter Miksza. (2007) Music participation and socioeconomic status as correlates of change: A longitudinal analysis of academic achievement. Bulletin of the Council for Research in Music Education, 41-57. info:/

July 16, 2009
02:46 PM
719 views

What does this anthropologist think about hormonal birth control? Part II

by Kate Clancy in Laboratory for Evolutionary Endocrinology

So I've covered a bit of my bias against hormonal contraception ads, and the basic no-nos. But one of the things you may have heard a lot lately is that women don't "need" a period, or even that it is "useless." I'd like to spend a little time unpacking this in the second part of my series.What is normal?Recently, in the beginning of an evolutionary medicine volume, I read in the editors’ opening comments that there is “nothing biologically normal” about monthly menses, as a way to put forward the idea that women should take continuous oral contraceptives (Stearns and Koella 2008, p. 4). Nothing biologically normal? Whether we like it or not, frequent menses in the United States is biologically normal, due to the fact that we eat a lot and don’t move around much at all. We’re at the far end of the spectrum of variation in reproductive function, but we have not fallen off the end of the continuum. On the one hand, I appreciate the attempt of the authors to try to shake things up and introduce the possibility that American physiology is not the global standard, but any body that responds appropriately to its ecology is, by definition, normal. Does this appropriate and evolutionary response to environment have its own consequences? Yes; you can lay the blame for the increased incidence of reproductive cancers in developed countries mostly on the flexible responsiveness and resource allocation capabilities of our reproductive systems. Your genes are important in determining your chances of breast cancer, but so are cumulated years of cheese fries and driving to work. (And before you think this is some sort of diatribe against overweight folks, plenty of normal weight folks – normal for Americans – have more unhealthy eating patterns than overweight folks. It’s not how you look but how you live, even when in broad strokes evidence can initially suggest it’s about the weight one carries.)Here is the reason Stearns and Koella (2008), and Eaton (Eaton et al. 1994; Eaton et al. 2002), and others have been advocating continuous hormonal contraceptive use: it may decrease reproductive cancer rates. Let’s take a step back and first understand the context under which the human female reproductive system evolved: once upon a time we were eating less and moving more. Age at menarche (that’s when we get our first menstrual period) used to be much later, menses itself wasn’t particularly heavy or cumbersome, and few cycles were ovulatory (meaning that an egg is released for possible fertilization). Soon after reaching menarche (as in, within a few years) a woman has her first child. She breastfeeds intensively for the first few years, but continues to breastfeed at least occasionally for four years, maybe more. At some point towards the end of breastfeeding, or sometimes not even until breastfeeding was done, she would resume cycling, and in a few cycles likely get pregnant again.This pattern would continue, with some variations based on miscarriages, increasing age, seasonal variation in food availability, and other issues, until the woman hit menopause. Of course, for many women, their lives ended around that point or even before, but some number of women certainly survived to be grandmothers, if observation of current forager populations is any indication. This means that for most of a woman’s reproductive life she was pregnant or breastfeeding, and cycling only occasionally. Strassmann has a great analysis of this and comparison between populations (Strassmann 1997): the punchline is that an industrialized woman of today has around 400 menstrual cycles, while our ancestors, if modern foragers are an indication, had 50-100.Now let’s look at today’s industrialized, or developed-country woman: like men, she eats more and moves around less, largely because she is in school or working rather than getting her own food. She hits menarche earlier, and menses are more frequent and copious than her ancestors, which creates lots of tissue remodeling in the endometrium (the lining of the uterus). Many of her cycles are ovulatory, necessitating frequent tissue remodeling for the ovaries. She may cycle for years before having her first child, even decades, and with those frequent cycles come a higher exposure to endogenous (coming from within the body rather than a pill) sex steroids like estradiol and progesterone. Even if she breastfeeds for years, she will likely resume menstrual cycling sooner than her ancestors because she is better fed. She will probably have fewer pregnancies and births than her ancestors, which means more cycles in between pregnancies. She will most likely make it to menopause and beyond; because she is so much more likely to make it past menopause we are far more likely to notice the negative effects of all that hormone exposure, in the form of reproductive cancers.So while I disagree with the idea that there is “nothing biologically normal” about frequent menstrual cycles, I certainly agree that they are not doing us any favors. But is it the reproductive system that is at fault or the lifestyle? Should we artificially suppress the system in order to promote health, or make changes to the way we live? I’m sure the answer lies somewhere in between, at least as we move towards building more sustainable neighborhoods and taking better care of our environment in developed countries.The third part of this series will address population variation in reproductive function, and how this impacts the efficacy and side effect incidence of hormonal contraceptives.ReferencesEaton SB, Pike MC, Short RV, Lee NC, Trussell J, Hatcher RA, Wood JW, Worthman CM, Blurton-Jones NG, Konner MJ, Hill KR, & Bailey R (1994). Women's reproductive cancers in evolutionary context Quarterley Review of Biology, 69 (3), 353-367Eaton, S.B., Strassmann, B.I., Nesse, R.M., Neel, J.V., Ewald, P.W., Williams, G.C., Weder, A.B., Eaton III, S.B., Lindeberg, S., Konner, M.J., Mysterud, I., & Cordain, L. (2002). Evolutionary health promotion Preventive Medicine, 34, 109-118Stearns S, and Koella J, editors. 2008. Evolution in health and disease. 2nd ed. Oxford: Oxford University Press.Strassmann, BI (1997). The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population Current Anthropology, 38 (1), 123-129 DOI: A1997WD24700015This post was written by Kathryn Clancy for the Laboratory for Evolutionary Endocrinology Blog. Except as noted, it is (C)Kathryn Clancy and licensed under a Creative Commons License. The opinions on this blog are the opinions of the blog author only, not the author's employer or colleagues.... Read more »

Eaton SB, Pike MC, Short RV, Lee NC, Trussell J, Hatcher RA, Wood JW, Worthman CM, Blurton-Jones NG, Konner MJ.... (1994) Women's reproductive cancers in evolutionary context. Quarterley Review of Biology, 69(3), 353-367.

Eaton, S.B., Strassmann, B.I., Nesse, R.M., Neel, J.V., Ewald, P.W., Williams, G.C., Weder, A.B., Eaton III, S.B., Lindeberg, S., Konner, M.J.... (2002) Evolutionary health promotion. Preventive Medicine, 109-118.

Strassmann, BI. (1997) The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population. Current Anthropology, 38(1), 123-129. DOI: A1997WD24700015

July 16, 2009
02:40 PM
1,068 views

No spikes in this worm: Motor neurons without action potentials

by Zen Faulkes in NeuroDojo

If you know a little bit about neurons, even really basic stuff, you probably know that neurons send signals with action potentials (a.k.a. spikes). What fewer people know is that there is great diversity in how neurons signal. There are many sensory neurons and interneurons that work entirely without action potentials. I once asked my Ph.D. supervisor, Dorothy Paul, “Is there such a thing as a non-spiking motor neuron?” Dorothy did most of her research working on non-spiking sensory neurons in the west coast mole crab, Emerita analoga. She didn’t give me the answer, but told me it was an excellent question and I should think about it. Some time later, I heard another student asking the same question to another researcher at a poster at a Society for Neuroscience poster, and the person said, “No.”This paper says the answer is, “Yes.” There are non-spiking motor neurons. Qiang Liu and colleagues did their research on the little nematode worm, Caenorhabditis elegans, and were able to take advantage of the huge knowledge of the genetics of this beast, and our ability to manipulate this animal’s genes. They recorded the output of muscle cells using standard electrical recordings, but instead of using electricity to stimulate the motor neurons controlling those muscles – the classical way of doing things – they genetically engineered the worm.The authors were able to make the worms express a protein called channelrhodopsin in certain neurons. Rhodopsin is a visual pigment that responds to light. When you flash a light on these worms (did I mention they’re transparent?), the channelrhodopsin opens up a channel that allows electrical current to flow into the neuron. Thus, you can use a flash of light to fire neurons of your choosing.In neurons with action potentials, activity is like a light switch: flipping the switch harder doesn’t make the light from the bulb any brighter. A key set of data is to increase the light intensity stimulating the motor neurons (shown by different line colours in the figure here), and record the response of the motor neurons. If there was a classic action potential in the motor neuron, you’d expect there to be no response until you hit a threshold, and always the same response in the muscle. But the effect is more like a dimmer than a switch: the greater the light intensity to the motor neurons, the more the muscles responded. This is just what you would as expect for a non-spiking neuron.There rest of this paper revolves around characterizing the synaptic connections between motor neuron and muscle in much more detail. It mainly looks at how the strength of connections between the cells change with repeated stimulation of the motor neurons.This is not the first demonstration of non-spiking motor neurons. Another nematode, Ascaris, probably claimed that honor two decades ago (Stretton and Davis 1989). So while I did learn quite a bit from this paper (I didn’t know about the Ascaris work) and am impressed with the techniques in this paper, I am still a bit puzzled as to why it’s in Proceedings of the National Academy of Science (PNAS). PNAS is one of those exclusive high profile journals, sometimes disparagingly called a “glamour mag,” that publishes on what it considers to be “high impact” science. I guess this paper made it in because C. elegans has become such an important model organism, because this paper doesn’t show any previously unknown or unexpected kind of phenomenon.But considering that the Ascaris work was published before I asked my supervisor about non-spiking motor neurons, I suppose that the phenomenon could stand to be much better known in the neurobiology community.ReferencesLiu, Q., Hollopeter, G., & Jorgensen, E. (2009). Graded synaptic transmission at the Caenorhabditis elegans neuromuscular junction Proceedings of the National Academy of Sciences, 106 (26), 10823-10828 DOI: 10.1073/pnas.0903570106Davis RE, Stretton AO. 1989. Signaling properties of Ascaris motorneurons: graded active responses, graded synaptic transmission, and tonic transmitter release. J Neurosci 9(2):415-425. http://www.jneurosci.org/cgi/content/abstract/9/2/415... Read more »

Liu, Q., Hollopeter, G., & Jorgensen, E. (2009) Graded synaptic transmission at the Caenorhabditis elegans neuromuscular junction. Proceedings of the National Academy of Sciences, 106(26), 10823-10828. DOI: 10.1073/pnas.0903570106

July 16, 2009
01:47 PM
720 views

What does this anthropologist think about hormonal contraception? Part II

by Kate Clancy in Laboratory for Evolutionary Endocrinology

The second part in the series on biological anthropology, ecology, variation, and hormonal contraception.... Read more »

Eaton SB, Pike MC, Short RV, Lee NC, Trussell J, Hatcher RA, Wood JW, Worthman CM, Blurton-Jones NG, Konner MJ.... (1994) Women's reproductive cancers in evolutionary context. Quarterley Review of Biology, 69(3), 353-367.

Eaton, S.B., Strassmann, B.I., Nesse, R.M., Neel, J.V., Ewald, P.W., Williams, G.C., Weder, A.B., Eaton III, S.B., Lindeberg, S., Konner, M.J.... (2002) Evolutionary health promotion. Preventive Medicine, 109-118.

Strassmann, BI. (1997) The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population. Current Anthropology, 38(1), 123-129. DOI: A1997WD24700015

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