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There are few experiences better than watching hummingbirds fly over a vineyard while sitting outside in the sunshine eating waffles. My wife and I have just been travelling through California for some much-needed rest and relaxation. We spent the last two days in the incredible Seven Quails vineyard (if you’re looking for accommodation near Paso Robles, stay there) and each morning, we delighted to see hummingbirds flitter between the trees of their back garden, against panoramic vistas of vines and rolling hills.

I’m assuming all of these photos are of the black-chinned hummingbird but if anyone has any other identification ideas, let me know. The money shots of the bird in flight were taken by my wife. The ones in the tree were me.

John Huchra, a leading astronomer at the Harvard-Smithsonian Center for Astrophysics, passed away on Friday. I’m not sure of the cause, but he had been suffering from heart problems; he was 61 years old.

John was most obviously known for his scientific accomplishments, especially as a guiding force behind the CfA Redshift Survey. For you youngsters out there, this project was the pioneering effort at mapping the large-scale structure of the universe. It revealed, to the surprise of many, that there was a lot of structure out there! The iconic image of cosmology in the 1980’s was the “CfA Stickman” reveal in the famous A Slice of the Universe paper by Valerie de Lapparent, Margaret Geller, and Huchra.

The stickman was not the universe being playfully anthropomorphic, it was simply the Coma cluster as distorted in redshift space. (You measure positions on the sphere of the sky, but velocities along the line of sight; converting these velocities to distances is inevitably distorted because galaxies in a cluster have peculiar motions inside the cluster.) Before this map was released in 1986, many people assumed that the galaxy distribution would be basically uniform on these scales. They shouldn’t have thought that, in retrospect (you need to go to larger scales before the uniformity becomes apparent), but sometimes it takes real data to get a point across. The survey went on to discover the Great Wall of galaxies, arguably the largest known “object” in the universe.

John had a number of other important contributions, including measurements of the Hubble constant and the discovery of Huchra’s Lens, one of the most dramatic early examples of gravitational lensing. He was also very active in the community, serving as president of the American Astronomical Society and numerous other roles.

But many of us will remember him mostly for his spirit and good humor. When I was a graduate student at CfA, he was one of the most friendly and helpful senior faculty members around, someone you were always happy to bump into in the hallways. There is a guestbook here for people to leave their reminiscences about John; he will be greatly missed.

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Have you ever been to an aquarium where large swarms of jellyfish swim around each other in a beautifully lit tank? Have you ever wondered how those drifting tentacles managed to stay untangled, when humans can’t even manage to put a set of headphones in our pocket without ending up with a series of mind-bending knots? Have you ever wondered what would happen if jellyfish did get their tentacles in a twist?

Well, thanks to Monterey Bay Aquarium’s jellyfish exhibit, I can tell you the answer to that last question: hilarity ensues. These are lion’s mane jellyfish. They have no brain or central nervous system, which is fortunate because otherwise, they would probably die of embarrassment.

I shot these photos/videos myself yesterday. The aquarium is incredible. More photos to come later today, and then tomorrow, some brand new science for you.

I guess there were some reporters in the crowd for my debate on Friday with PZ Myers and Victor Stenger (and with Eugenie Scott, who was in my broad camp). Here’s from an LA Times story that just appeared:

With that background, and with the legacy of 9/11 providing impetus to those who see religious fundamentalism as a threat, there was a sense of urgency at the Biltmore conference about finding the right approach. Should nonbelievers confront the religious or try to get along?

Even “accommodationist” atheists are not known for mincing words, and although there were periodic reminders that those at the gathering shared “99% of our intellectual DNA,” as author Chris Mooney put it, the disagreements were not exactly gentle.

When Mooney, a leading voice for accommodation, said there was nothing to stop a nonreligious person from being spiritual, Myers’ reaction was nearly physical. “Whenever we start talking about spirituality,” he said, “I just want to puke.”

Mooney said nonbelievers need to pick their fights and to form alliances with religious people who share their views on particular subjects, such as the importance of stem cell research.

I’m pleased that my sound bite about how we share “99 percent of our intellectual DNA” got in there, because it was central to my message. And while there’s certainly still a sharp debate here, my sense at the conference is that it’s actually turning somewhat healthier, more dialogue-like.

That’s a good thing.

You can read the full LA Times story here. Meanwhile, the next episode of Point of Inquiry, which should be available shortly, will have much more about this….

Click here to view the embedded video.

A bit of a tour of a shuttle on Pad39A by astronaut Mike Massimino.

Source

Published on 10/10/10 at 10:10

In astronomy, a Trojan is an asteroid or moon that shares an orbit with a larger asteroid or moon, but does not collide with it.  The Trojan orbits within one of the Lagrangian points of stability ahead or behind the main body.

Usually the asteroids which accompany Jupiter around its orbit come to mind when you mention the Trojans.  The Jupiter asteroids were the first discovered, and are believed to be almost as numerous as those in the asteroid belt.  Since the Jupiter Trojans were discovered, scientist have found “Trojans” in the orbits of Mars, Neptune, and Saturn.

Discovered in Jupiter’s orbit in 1906 (588 Achilles was the first one), there have been 4,076 Jupiter Trojans found so far.  There are believed to be over a million Jupiter Trojans larger than 1 km in diameter.  As in the main asteroid belt, the Trojans form asteroid “families”.  Currently, most scientist believe the Trojans are “captured” Kuiper Belt Objects.  Sometimes the “capture” appears to imperfect.  The comet Shoemaker-Levy 9 is believed to have been one such imperfect capture.

Currently there are only four known Mars Trojans, and seven around Neptune.  There may be many more Trojans than those recorded so far; we’re just not in a position to see them yet.  Perhaps when New Horizons passes Neptune…

Martian Trojans, image by Andrew Buck, all rights reserved

There is some speculation that the Trojans are a source for new short-period comets and Centaurs.  Considering the four discovered around Mars, that puts them in our very near back yard.

Miriam Goldstein was kind enough to alert me of this charming panel up at Comically Vintage entitled, “When scientists meet.” For obvious reasons, it goes straight into the Science of Kissing Gallery!

Submit your original photo or artwork for consideration here.

I have a strange job. A few weeks back I was wandering through the aisles of the local Walmart, searching for bug spray, when my phone rang. A very excited Robert Krulwich was calling. As I drifted past the potato chips and plasma-screen TVs, he declared to me with great excitement that I was going to be on the cable series Weeds.

Now, I’m pretty sure that if I had actually auditioned for the show, I would remember it. Or at least I could find some trace of the experience over on IMDB, searching for my name in the role of Pothead #8. So there I was at the store, getting totally lost trying to figure out what Krulwich was saying.

Gradually, the story emerged: a few months ago, I joined Krulwich and his partner in radio crime, Jad Abumrad to tape a couple segments for their fine show, RadioLab. In one of those segments, I describe the glories of parasites, focusing on one surgically fiendish wasp. Apparently the people at Weeds are RadioLab fans and sometimes work bits of it into their own show. And apparently, they are using my ramblings–at great length, I’m reliably informed–in the season premiere. What deeper meaning that Jad, Robert, and I could bring to their show, I can’t say–in part because I don’t have cable TV, so I’m not a regular viewer.

Suffice to say, it was a very long bug spray run. The new season airs tonight. If anyone sees it, fill me in! And if I can get my mitts on the clip, I’ll post it.

[Update: We've got it]

There is a lot of space to explore and a limited amount of money to spend. So every ten years the National Research Council’s “Decadal Survey“ recommends which astronomy and astrophysics projects should get first dibs. Last week, the committee released their recommendations for 2012 through 2021. The projects that got the thumbs-up from astronomers would tackle big tasks, like hunting for dark energy and seeking out new exoplanets.

Though funding agencies (like NASA, the National Science Foundation, and the Department of Energy), Congressional committees, and the scientific community often use the survey to select the observatories on which to focus attention and resources, some were skeptical about this report given the 2001 survey’s recommendations and results.

Although these reports have always been influential—policymakers like scientists to rank their needs—only two of the seven major projects that appeared on the wish list in the 2001 survey have been funded, leading astronomers to wonder if the exercise is as useful as they’d like it to be. Previous surveys have also been faulted for providing unrealistic cost estimates, as low as a fifth of what certain missions have ended up costing. As a result, there has been considerable pressure on the committee that authored [Friday's] report to prioritize projects more effectively and estimate costs better. [Science Insider]

This time, the committee hoped to avoid these budget underestimates by evaluating the financial and technical risk of each project.

“I think at the time of the previous decadal survey, people didn’t appreciate the importance of taking a second look at the cost of things and not just taking the word of the people submitting the projects,” says astronomer Claire Max of the University of California in Santa Cruz, a member of the final survey committee. This time around, the panel hired an outside expert to help estimate the funding and technical risk of each project. [Nature News]

Nature News outlines the survey’s funding recommendations for a wide range of projects, but two observatories–one in space and one on the ground–seem most promising to the committee, fitting with the survey’s major three priorities.

The committee highlighted three main areas of science, none of which should be too surprising to those who follow the field: Cosmic Dawn, New Worlds and the Physics of the Universe. Or, how did all of this get here, are there planets like Earth nearby, and what makes up the universe? Projects that are well suited to answer these questions, as well as technologically feasible, were given high recommendations. [Discovery News]

In Space

The survey recommends the most funding for the Wide Field Infrared Survey Telescope (WFIRST), a joint project between NASA and the Department of Energy, which has an estimated cost of $1.6 billion. After an expected launch in 2020, WFIRST will record light from distant supernova among other things, and hopefully provide insights into the universe’s expansion and dark energy. Committee members also believe the telescope may help in the hunt for exoplanets.

“WFIRST not only gets at all the dark energy [priorities], but it also has significant capability in exoplanet science and will do outstanding work in infrared survey science,” Michael Turner, a cosmologist at the University of Chicago and the Kavli Institute for Cosmological Physics told physicsworld.com. Turner, who served on the 23-member committee for the decadal survey, also notes that the survey did not reject the idea of a possible collaboration with the European Space Agency (ESA) to combine its planned Euclid dark-energy mission with WFIRST. [Physics World]

On the Ground

The survey also recommends support for the $463 million Large Synoptic Survey Telescope (pictured above). When completed, the telescope will survey the entire sky every week with a three-billion pixel digital camera to help researchers understand dark matter, dark energy, supernovae, near-Earth asteroids, and Kuiper belt objects.

In placing the LSST atop its priority list, the report highlighted the telescope’s technical readiness and its “compelling science case and capacity to address so many of the science goals of this survey,” including exploring the fundamental physical makeup of the universe by probing the nature of dark matter and dark energy. [Scientific American]

The DISCOVER blog Cosmic Variance has more on all this: 
The Next 10 Years of Astronomy explains what the Decadal Survey means to astronomers 
The Next Decade of US Space Astronomy
The Next Decade of US Ground Based Astronomy

Image: LSST Corporation

They only wanted to show their disapproval. Friends eager to counterbalance all those Facebook “Likes” rushed to “Download the official DISLIKE button now” as received in a message. But, sadly, no dislike button was in store. Instead, installing the application provided users with several surveys and left their profiles vulnerable to spammer control. If there was ever a time to unleash their Dislike, this was it.

Yet, as Graham Cluley of the security firm Sophos told the BBC–mentioning a similar ploy that offered Facebookers the chance to see an anaconda vomiting up a hippo–such “survey scam” applications are nothing new:

“Anyone can write a Facebook app–these scams are constantly springing up.”

Perhaps Facebook should take note: Users were willing to sacrifice their security for the mere power to express negative feedback. Or, at least, the mere power to express negative feedback without typing.

Perhaps a compromise is in order? Unfortunately, a new Meh button application seems to need some tweaking. As in the Atlantic Wire:

Turns out, every time you click the “meh” button it registers your vote—allowing an individual user to “meh” something 10,000 times or more. That’s a lot of indifference.

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There are great plays and bad ones, but the playwright’s actual text is only one aspect of a production. The very same words can take on radically different meanings depending on the whims of the director, the abilities of the actors and the setting of the stage. The same is true of our genes and our environments. In cases where genes affect our behaviour, the same stretch of DNA can lead to very different deeds, depending on individual circumstances. Just as a production defines a play, environments and cultures alter the effects of certain genes.

Heejung Kim from the University of California has discovered a great example of this effect by studying a gene called OXTR (or the ‘oxytocin receptor’, in full). The gene creates a docking station for a hormone called oxytocin, which is involved in all sorts of emotions and social behaviours, from trust to sexual arousal to empathy.

Kim looked at a specific version of the OXTR gene, whose carriers are allegedly more social and sensitive. But this link between gene and behaviour depends on culture; it exists among American people, who tend to look for support in troubled times, but not in Korean cultures, where such support is less socially acceptable. Culture sets the stage on which the OXTR gene expresses itself.

OXTR varies from person to person, and the DNA ‘letters’ at particular spots can affect the way we behave. According to previous studies, people with a ‘G’ at one specific site tend to be more sensitive parents, more empathetic and less lonely than those with an ‘A’. But most of these studies have been done with white, Western people who are hardly representative of the world at large – in fact, they’re positively W.E.I.R.D.

To looked outside this “thin and rather unusual slice of humanity”, Kim compared 134 Korean students with 140 American ones, all with comparable splits of age, gender and background. Using a questionnaire, she measured how stressed each volunteer was feeling at that point in their lives, and how they cope with stress. As with previous studies, Kim found that Koreans are less likely than Americans to turn to their social circle for support and they get less out of doing so; they are more concerned about burdening their friends and straining their relationships.

The OXTR gene exerts its influence against the background of these contrasting cultural conventions. Distressed Americans with one or more copies of the G version were more likely to seek emotional support from their friends, compared to those with two copies of the A version. But for the Koreans, the opposite was true – G carriers were less likely to look for support among their peers in times of need (although this particular trend was not statistically significant). In both cases, the G carriers were more sensitive to the social conventions of their own cultures. But the differences between these conventions led to different behaviour.

And in a further example of the influence of the environment, Kim only found this pattern among people who were experiencing a lot of stress. In the low stress group, she found that Americans were indeed more likely to seek emotional support than Koreans, but their OXTR gene had no bearing on their choices.

Of course, Koreans and Americans differ not just in their cultures, but in their genes (including many others beyond OXTR). To account for that, Kim also worked with a small group of 32 Korean-Americans who were born and raised in the US, but were genetically Korean. Kim found that the link between OXTR and emotional support among these volunteers was much closer to the culturally similar Americans than the genetically similar Koreans.

Richard Ebstein, who has worked on OXTR before, says, “Overall, I would say it’s a very interesting finding… These types of studies are needed to help us get a better understanding of how it’s not just nature or nurture but rather the interplay between the two that contributes to how we deal with the social environment.” However, he’s not convinced (and nor am I) that Kim looked at enough people, particularly in the extra experiment with the Korean-Americans. Ebstein wants to see them repeat the results in a much larger group.

Even so, Kim’s results are compelling. They’re also unusual in looking for an interaction between genes and culture. Many studies have looked at how nature and nurture work together but in most cases, the “nurture” bit involves something social that’s either harsh or kind, such as loving or abusive parenting. In one of the most famous examples, people with the ‘low-activity’ version of the MAOA gene tend to be more aggressive than those with the ‘high-activity’ one, but only if they’ve been abused or neglected as children. Kim’s study stands out because it looks as cultural conventions instead, and Ebstein says that it “provides an interesting new avenue for researching gene-environment interactions.”

Kim also hopes that her work will encourage more scientists to investigate the ways in which genes and culture evolve together. She notes that the G version of OXTR is more common among white Americans than Korea. It’s tantalisingly possible that American culture has come to emphasise social support partly because more people have genes that skew them towards social behaviour. So genes constrain culture, while culture creates the stage on which genes exact their influence.

Reference: PNAS http://dx.doi.org/10.1073/pnas.1010830107

More on genes and environment:

• Good teachers help students to realise their genetic potential at reading
• The MAOA guide to misusing genetics
• Ask an IVF baby: does smoking while pregnant lead to antisocial behaviour?
• Saucy study reveals a gene that affects aggression after provocation
• Making sense of obesity genes

If the citation link isn’t working, read why here

In early 2010, some scientists offered their predictions for the new decade which this blog covered in the post, “Scientists Predict: The 2010s Will Be Freakin’ Awesome–With Lasers.” In what could be an early sign of that sunny prognostication coming true, researchers have announced that they’ve controlled the beating of an embryonic heart with an infrared laser beam. While the work is in its early stages, researchers say this remarkable advance will help them study heart disease and could one day lead to optical pacemakers.

The embryonic hearts in question came from quail eggs. Each quail embryo was only two or three days old so the heart measured just 2 cubic millimeters in volume; at that stage, the heart is essentially a clump of cells that hasn’t yet developed its four-chambered structure. The pulses of infrared light were delivered by an optical fiber that ended 500 micrometres from the embryo.

Before they switched on the laser, the heart beat once every 1.5 seconds, but firing the laser twice a second quickened the heartbeat to match the laser rate as long as the laser fired…. ”It worked beautifully: the heart rate was in lockstep with the laser pulse rate,” says [study coauthor] Duco Jansen of Vanderbilt University in Nashville, Tennessee. [New Scientist]

Several years ago, a different scientific team showed that laser pulses could set the pace of a cluster of heart cells in a petri dish, but the new study, published in Nature Photonics, marks the first time a laser has set the pace of an entire heart. Lead author Michael Jenkins of Case Western Reserve University says the technique will offer a new way to study heart development. 

“We want to know how congenital heart defects form, and how the heart’s rhythms during development affect it later on,” he says. “Having a noninvasive way to modify the heart rate would be useful.” [ScienceNOW]

At the energy level used the laser pulses didn’t appear to damage the cells, but the researchers intend to thoroughly investigate the safety of the process. They’ll also be looking into other details–like how exactly this mechanism works. At the moment, it’s still unclear.

They suggest that it might create a temperature gradient that can stimulate “action potential in excitable tissues,” as was also proposed in earlier work on clusters of cardiomyocytes. [Scientific American]

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Image: Salma Shaikhouni

Over on Randi’s site, they just posted this image of His Skepticalness and a familiar spaceship:

When I saw it, my first thought was, "I find your lack of faith… refreshing."

How would you caption this picture?

In my post on Empires of the Word I observed that quite often the written record is silent on many matters which only language or genes tell us must have occurred. The Indo-Aryan character of the dominant language on the island of Sri Lanka seems to be a geographical anomaly in the least, but perhaps most strange of all is the existence of a language and ethnic group of clear Southeast Asian provenance on the island of Madagascar. To my knowledge Arab, Persian and South Asian sources do not record the existence of a prominent Southeast Asian maritime diaspora which spanned the Indian ocean in the years before 1000 A.D., but we know that it did exist. A new paper on the genetics of the island of Comoros fleshes out another piece of the puzzle, Genetic diversity on the Comoros Islands shows early seafaring as major determinant of human biocultural evolution in the Western Indian Ocean:

The Comoros Islands are situated off the coast of East Africa, at the northern entrance of the channel of Mozambique. Contemporary Comoros society displays linguistic, cultural and religious features that are indicators of interactions between African, Middle Eastern and Southeast Asian (SEA) populations. Influences came from the north, brought by the Arab and Persian traders whose maritime routes extended to Madagascar by 700–900 AD. Influences also came from the Far East, with the long-distance colonisation by Austronesian seafarers that reached Madagascar 1500 years ago. Indeed, strong genetic evidence for a SEA, but not a Middle Eastern, contribution has been found on Madagascar, but no genetic trace of either migration has been shown to exist in mainland Africa. Studying genetic diversity on the Comoros Islands could therefore provide new insights into human movement in the Indian Ocean. Here, we describe Y chromosomal and mitochondrial genetic variation in 577 Comorian islanders. We have defined 28 Y chromosomal and 9 mitochondrial lineages. We show the Comoros population to be a genetic mosaic, the result of tripartite gene flow from Africa, the Middle East and Southeast Asia. A distinctive profile of African haplogroups, shared with Madagascar, may be characteristic of coastal sub-Saharan East Africa. Finally, the absence of any maternal contribution from Western Eurasia strongly implicates male-dominated trade and religion as the drivers of gene flow from the North. The Comoros provides a first view of the genetic makeup of coastal East Africa.

In the paper they note that ~6% of the Y chromosomal lineages were Southeast Asian, while ~15% of mtDNA lineages were. That indicates that the Southeast Asian presence on the Indian ocean was a case of folk migration, men, women and children on the move. The data from Madagascar indicate something similar, both male and female lineages show Southeast Asian imprint among the highland Malagasy (I don’t make much of the proportional difference because this is just one sample). In contrast, they show in this paper that there’s a substantial West Eurasian (probably Arab, Indian and Persian) Y chromosomal gene flow into the population of Comoros, but no West Eurasian mtDNA. So in this case you have a clear contrast with that of the Southeast Asian seafarers, the Muslim merchants who settled on the Comoros did not bring their children or womenfolk. It was not a folk migration, but a mercantile network. Because of the nature of the sources, and the cultural influence of the West Asians, we know of their presence from the historical record. In contrast, the arguably more substantial folk migration of Southeast Asian seafarers from Borneo is hidden in the text. They may have been of no concern or beneath mention from the perspective of the Muslim merchant princes, but the fact that they were no longer on the high seas by the time the Portuguese arrive may also indicate that they were driven off by the same Muslim merchant princes in the years after 1000. If the latter is the case the silence may be due to the inclination to forget an unpleasant rivalry.

All this goes to show that history’s reliance on text can mislead and obscure real dynamics. Even social and economic history which attempts to tunnel-down to the level of the populace is still heavily reliant on written records. In the case of seafarers it seems likely that even archaeologists would be unable to detect their movements because of the liminal nature of their settlements. The linguistic and cultural influences in Madagascar and in East Africa indicate a sojourn by Austronesians in that coast, but there is no physical or textual record. There is the “dark history” which we ignore because of current ideological preferences, and then there is the dark history which has fallen outside of our methodological window.

Dienekes has more on this paper.

That grease trail you’ve smeared on your smart phone’s touchscreen could give away more than your lightsaber skills or virtual girlfriend’s whims: Would-be smudge attackers, a recent paper argues, could follow your finger oils as a clue to your passcode.

In the paper “Smudge Attacks on Smartphone Touchscreens,” which we first saw on Gizmodo, a team in the computer science department at the University of Pennsylvania tried to pick out grease patterns from Android phones by photographing the phones and enhancing the patterns with photo-editing software. From the paper’s introduction:

“We believe smudge attacks are a threat for three reasons. First, smudges are surprisingly persistent in time. Second, it is surprisingly difficult to incidentally obscure smudges through wiping or pocketing the device. Third and finally, collecting and analyzing oil residue smudges can be done with readily-available equipment such as a camera and a computer.”

Though the smudge alone can’t confirm the exact passcode, the study’s authors hint that it may help an attacker rule out possibilities. In the paper, the authors describe the three by three number grid of “contact points” that some earlier Android phones employed for entering passcodes. The team assumed three limitations on smudge patterns using this grid: it must have four or more contact points; it cannot use any contact point more than once; and if there is any contact point between two others on a smudge trail, then it must also be a contact point. They calculate that using just the last of these restrictions, an attacker could reduce the number of possible patterns from 1 million to 389,112 patterns–a way to reduce a phone lockout during hacking.

The study also investigated the best conditions for identifying a smudge pattern. A particularly easy partial pattern to find, the researchers say, appeared when the phone was “dirty prior to password entry,” i.e. after the user had just finished chatting, allowing the phone’s screen to soak up some extra face dirt for finger smudge contrast.

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Image: flickr / p_kim

Cadavers and mummies as therapeutic means

“Sickness befallen onto him, man found that plant and animal derivatives invigorated him. Thereafter, he found a therapeutic benefit in using man as a means of self cure and especially, dead man from violent death. The foam of the skull of cadaver was an excellent antiepileptic as well as blood coming out from a freshly decapitated man. By applying on diseased parts of his body, so as to get rid of inflammation or infection, cadaver’s hands were used against tumors of all kinds. Dead human skin were processed into belts and used therein for helping delivery of parturition women. The mummy must be blackish, foul smelling and hard. Those who were whitish, odorless and powder-like, were unfit for use. Mummy powder applied to the nose would stop nose bleeding. Ambroise Paré (1510-1590) was an adversary of those practices.”

Photo: flickr/Michael Scheltgen

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This morning, astronauts at the International Space Station are once again venturing outside of the ISS, undertaking the third spacewalk in their attempt to fix the station’s cooling system.

The crew is in no immediate danger, as their backup cooling system is working. However, the ammonia leak in the coolant system caused the astronauts to turn off some experiments and backup systems keep keep the ISS from overheating.

The space station has been working at reduced cooling capacity since the pump first failed on 31 July. The enormous pumps circulate ammonia in heat exchangers outside the station, where water cannot be used because it would freeze [BBC News].

During their first two spacewalks, one of which went on for eight hours, astronauts Douglas Wheelock and Tracy Caldwell Dyson removed the leaking old pump. This morning they managed to free the new one from the platform where spare parts are kept. It should take one more spacewalk after today’s to complete the job.

NASA station managers have said the ammonia pump failure has been one of the most challenging repairs for the International Space Station ever attempted. The cooling system is so critical to station operations that a pump repair is one of 14 major failures for which NASA engineers have prepared emergency plans for in advance, they added. There are four spare ammonia pumps on the space station, one of which will be used for this repair. Each pump weighs 780 pounds (353 kg) and is 5 1/2 feet long (1.6 meters) by 4 feet wide (1.2 meters) [Space.com].

Those of you who stayed up late last week to catch the Perseid meteor shower might be wondering whether all those rocks pose a threat to astronauts floating around outside the ISS. But NASA meteor experts say that even with Earth traveling through this haze of comet leftovers, the threat to astronauts is still less than that posed by the space junk orbiting our planet.

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Image: NASA (2006 spacewalk)

If you’re trapped in a building, it’s probably not the best time to start setting fire to things. But this is exactly what some bacteria do when they find themselves in a human; they cause diseases that are potentially fatal but not contagious. Without an escape, they risk going down with their host. This seems like a ludicrous strategy but we’re looking at it from the wrong perspective – our own. In truth, humans often have nothing to do with the diseases that plague us; we’re just collateral damage in an invisible war.

Like all living things, bacteria have to defend themselves against predators like amoebas. Some species do so using resistance genes that turn them from passive victims into aggressive fighters. And by coincidence, these same adaptations make them more virulent (good at causing disease) in human bodies. We’re just caught in the crossfire.

The idea that virulent bacteria have adapted to entirely different problems is called the “coincidental evolution hypothesis”. Sandrine Adiba from Pierre and Marie Curie University found evidence to support it by showing that the typically harmless gut bacterium Escherichia coli can cause disease in mice after it’s exposed to the threat of amoebas.

E.coli is mostly harmless, but some strains can cause severe food poisoning. When it’s not colonising the guts of mammals, it’s found in the soil; in both environments, it’s threatened by roving amoebas, which effectively engulf and digest it. Adiba found that one such predator – an amoeba called Dictyostelium discoideum – was very good at munching its way through harmless strains of E.coli, but a disease-causing strain known as 536 was too much to swallow.

Once engulfed, this hardy strain actually managed to reproduce inside the amoeba, weakening and eventually killing it. And if it can do that in a hungry amoeba, it can do that in a mammal cell; from its point of view, the two environments aren’t that different. Adiba confirmed that by pitting 31 different strains of E.coli against Dictyostelium. She found that those which tend to live in harmony with mammals also succumbed to amoebas, while resistant strains tend to cause disease.

The resistant strains had several genes that allowed them to avoid death by digestion. Some shield E.coli from enzymes called lysozymes that break down the outer walls of their cells. Others allow it to find food, by scavenging iron from within the amoeba’s body. These genes help to foil predators, but they’re also “virulence factors” that allow E.coli to successfully infect mammal cells. In fact, 76% of the resistant strains carry these weapons compared to just 16% of the vulnerable strains.

This was a single case study but it probably reflects a very common trend. Some scientists have suggested that for many bacteria, the ability to resist grazing amoebas came before the ability to cause disease in humans and other mammals. The former skill opened up the door to the latter.

There are many other examples that support this idea. Some E.coli strains wield poisons called Shiga toxins that are bad news for their hosts, but that also ward off a predator called Tetrahymena. When Salmonella enterica, another food poisoning germ, is threatened by amoebas, it ends up with more genetic variation at a part of its genome that affects how virulent it is.

Legionella pneumophila, which causes Legionnaires’ disease, might never even have been able to harm humans at all, were it not for amoebas. Legionella specialises in infecting our immune cells, including the macrophages that vacuum up foreign invaders. This ability to outsmart our defenders may again be coincidental; it’s more likely that the bacterium originally evolved to resist the digestive powers of amoebas, which also suck them up in the same way as macrophages.

And so far, we have just considered predators, which form one small part of the life of a bacterium. Competitors also shape their evolution. Earlier this year, I described how the normally harmless nose bacterium Streptococcus pneumonia becomes infectious when it battles against another species called Haemophilius influenzae. This competitor summons white blood cells to do away with Streptococcus, which can defend itself by producing a thicker coat. But this armour also allows Streptococcus to evade our own immune system, resulting in pneumonia, meningitis and other diseases. As I wrote back then, “many human diseases really have nothing to do with us at all.”

Reference: Adiba, S., Nizak, C., van Baalen, M., Denamur, E., & Depaulis, F. (2010). From Grazing Resistance to Pathogenesis: The Coincidental Evolution of Virulence Factors PLoS ONE, 5 (8) DOI: 10.1371/journal.pone.0011882

More on bacteria:

• When bacteria fight bacteria, we lose
• Fighting bacteria with bacteria – common nose germ provides new weapon against superbugs
• When enslaved bacteria go bad
• The bacterial zoo in your bowel
• Cooperating bacteria are vulnerable to slackers

If the citation link isn’t working, read why here

In June, I posted about a pinup calendar where the model was somewhat more naked than naked: in fact, the pictures were all X-rays!

I was fascinated by the implied raciness of the pictures, given that at best all you could see was a hint of curves. The poses themselves were provocative as well, and I wanted to spark a discussion of it.

One thing that should have occurred to me but didn’t was how the pictures themselves were made. Was a model exposed to X-rays? How much were the images enhanced? Were they real at all?

Well, now I know. An article at Radiology Daily gives the lowdown: no models were irradiated in the making of the calendar. The pictures were all CGI, though based on models in Playboy.

The interesting thing about the article, though, is that they do discuss the implied raciness, just as I did:

"Obviously, we didn’t want to expose models to dangerous radiation," [calendar art director] Schlichte said told Financial Times Deutschland. So the artists consulted a few issues of Playboy to determine "what poses look erotic if you’re not actually seeing anything," she said. Then they had a computer generate those poses in skeletal form.

As for "not actually seeing anything," that’s not quite accurate. Schlichte noted, "Anyone taking a close look at Miss April can see two silicon bags floating in front of her thorax."

Ha! I was thinking of using April in my original article, but decided the more obvious breasts (and the more suggestive pose, truth be told) made it a bit too adult for the blog. I chose February, where they’re a bit less ostentatious.

All in all, I think this was an interesting idea, and it certainly did get the conversation going in the comments!

Tip o’ the lead fedora to Babloggee Eric B.

In my recent OpEd with Michael Webber, we discuss the energy embedded in food waste–which accounts for at least 2% of the nation’s energy budget. We point out some ways to waste less such as reducing standard portion sizes and providing the right incentives for businesses, but acknowledge that ultimately, it comes down to consumer choices:

Foremost, the public needs to be better educated about proper storage of foods to keep them edible for longer. Shoppers could be supplied with easy-to-digest, accurate information about the proper shelf life of products, so that they are able to plan meals more carefully and end up with less spoilt food at the end of the week.

Another problem is “use by” dates, which are extremely conservative and can encourage consumers to throw away perfectly edible food. Similarly, “sell by” dates are usually meant as guidelines for retailers to ensure they do not keep stock too long, not as guidance to consumers about when the food will spoil. We need to improve the way we label foods.

Initiatives targeted at consumers could also have ripple-out effects: not only will educating people about food waste reduce pressure on their wallets, it would also lead to fewer trips to the store, saving on gasoline and reducing carbon emissions. Most important, it would help to promote a culture that places a higher value on food, energy, and the way their complex relationship affects us all.

But tackling this issue will be very tricky. Consider: Everyday bakeries throw out day old goods, catering companies dump excess meals, supermarkets do away with blemished fruits, and that’s just the tip of the iceberg…

I’ve long been a firm believer in the power of personal choice and am curious to hear your ideas. How might we shift public attitudes to be less wasteful and save energy on a massive scale?