Monday Science Links

This week's yummy science:

• Carl Zimmer at The Loom looks at E. coli (well, it's his latest book): There’s no better way to kick off Microcosm Week than with some chocolate chip cookies. Or, to be specific, some raw cookie dough carrying a dangerous cargo of toxic E. coli. The name "E. coli" embraces a veritable empire of bacteria. While all E. coli share the same backbone of certain genes, they can be divvied up into a vast number of strains, each with a distinctive genetic profile. Many of those strains are harmless. You have a couple dozen strains of E. coli dwelling inside you right now, quietly grazing on the extra sugar in your gut. But some strains are extremely nasty. One strain, known as E. coli O157:H7, can stick to the walls of the intestines and build needles through which it can inject molecules into host cells that can alter them in many ways, so that the cells disgorge food the microbe can eat. Typically this manipulation leads to painful, bloody diarrhea but little more. On rare occasion, however, the bacteria unleash toxins that can spread through the blood stream, killing cells and leading to kidney failure.
  
• Darren Naish at Tetrapod Zoology blogs on a new species of salamander: The naming of new amphibian species is a fairly routine thing. This doesn't mean that - despite the global amphibian crisis - amphibians are actually ok and that we can stop worrying; it means that we haven't been paying enough attention, and indeed many of the species that are being named anew are endangered, or threatened, or with tiny ranges. The current edition of Journal of Zoology includes the description of a new plethodontid salamander (aka lungless salamander): the Patch-nosed salamander Urspelerpes brucei Camp et al., 2009. The big deal about this entirely new species is that it's from the Appalachian foothills of Georgia, USA.


• Lee at Cocktail Party Physics looks at radiation around your home: The most common sources for ionizing radiation are nuclear reactions natural and man-made (fusion and fission) and natural radioisotopes. Don't know an isotope from an antelope? An isotope is a version of an element that has a different than usual number of neutrons (a different mass number) but the same chemical properties. A radioisotope emits enough EM energy to strip away the normally tightly bound electrons from an atom, making it a charged particle, like x-rays. Only the shortwave end of the EM spectrum has enough energy to do this—not the electrons coming out of your CRT TV. While it's true that every appliance in your house that uses an electric current is surrounded by an extremely low frequency (EMF) electrical field, that radiation is of the non-ionizing sort, even the microwave. The health hazards of this type of radiation are probably negligible in the low concentrations we're exposed to.There are some exceptions, of course. Stick your head in the microwave and you'll cook yourself, but that's because microwaves excite the water molecules until they give off heat. You won't be radioactive afterwards, just cooked. Likewise infrared radiation, which makes some beautiful photographs!). IR filters allow viewers to see differences in ambient temperature, which is why they're used in night scopes, but the radiation itself is not up to much more in everyday concentrations than heating you up a little.


• Kristjan Wagner at Pro-Science takes up cudgels against David Klinghoffer's DNA claims: One of the token non-Christian of the Discovery Institute, David Klinghoffer, has once again open his mouth to talk about stuff he knows nothing about. This time in the Jerusalem Post. "The alphabet of life DNA are three letters full of paradox. What they represent remains little understood by the public, yet they are on everyone's tongue. Amid the chatter of popular culture, the truth gets lost that DNA is one of the most powerful clues we have of the existence of a spiritual reality, maybe to the existence of God." One has to be in awe of Klinghoffer's ability to start up an article with something as mindbogglingly stupid as this paragraph. Yes, DNA is widely talked about by people who has little understanding of what it is. Klinghoffer is a good example of this. DNA is not in any way or sense a clue for "a spiritual reality, maybe to the existence of God".


• And Brian at Laelaps offers us a look at a new crocodylian: When I was trying to come up with a title for this post I almost went with "Armadillosuchus: An armored crocodylian you wouldn't want to mess with." Obviously I changed my mind. Not only was the title too long, but it was redundant to boot. All crocodylians are "armored" in that they have little bony plates called osteoderms (primarily on the dorsal, or top, side of their bodies) beneath their scales, which in turn overlay a layer of bony plates called osteoscutes. Crocodylians are tough! The newly-described crocodylian Armadillosuchus from the Late Cretaceous deposits of Brazil, however, was carrying a more bizarre complement of armor. Right behind its head was an armored dome of hexagonal plates. This bony buckler was rigid, but could be moved independently of the head so that the neck was not always locked in one position. Now comes the really interesting part. Behind this "cervical shield" was a series of about seven mobile armored bands. (What the researchers call "mobile-banded body armor.") This is very similar to what is seen in living armadillos, hence the croc's name Armadillosuchus. This crocodylian had "armadillo-like" armor even before the mammals did!