Sled Dog Blog Blue-eyed Humans Have A Single, Common Ancestor New research shows that people with blue eyes have a single, common ancestor. A team at the University of Copenhagen have tracked down a genetic mutation which took place 6-10,000 years ago and is the cause of the eye colour of all blue-eyed humans alive on the planet today. What is the genetic mutation "Originally, we all had brown eyes," said Professor Hans Eiberg from the Department of Cellular and Molecular Medicine. "But a genetic mutation affecting the OCA2 gene in our chromosomes resulted in the creation of a "switch," which literally "turned off" the ability to produce brown eyes." The OCA2 gene codes for the so-called P protein, which is involved in the production of melanin, the pigment that gives colour to our hair, eyes and skin. Limited genetic variation Variation in the colour of the eyes from brown to green can all be explained by the amount of melanin in the iris, but blue-eyed individuals only have a small degree of variation in the amount of melanin in their eyes.
First-ever high-resolution images of a molecule as it breaks and reforms chemical bonds When Felix Fischer of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) set out to develop nanostructures made of graphene using a new, controlled approach to chemical reactions, the first result was a surprise: spectacular images of individual carbon atoms and the bonds between them. "We weren't thinking about making beautiful images; the reactions themselves were the goal," says Fischer, a staff scientist in Berkeley Lab's Materials Sciences Division (MSD) and a professor of chemistry at the University of California, Berkeley. "But to really see what was happening at the single-atom level we had to use a uniquely sensitive atomic force microscope in Michael Crommie's laboratory." Crommie is an MSD scientist and a professor of physics at UC Berkeley. What the microscope showed the researchers, says Fischer, "was amazing." The researchers report their results in the June 7, 2013 edition of the journal Science , available in advance on Science Express .
Quackwatch Understanding the Fourier transform » #AltDevBlogADay Yes, I realize that after reading the title of this post, 99% of potential readers just kept scrolling. So to the few of you who clicked on it, welcome! Don’t worry, this won’t take long. A very long time ago, I was curious how to detect the strength of the bass and treble in music, in order to synchronize some graphical effects. What I found was the Discrete Fourier Transform (DFT), which looks like this: This formula, as anyone can see, makes no sense at all. Eventually, I was able to visualize how it works, which was a bit of a lightbulb for me. Disclaimer: my math skills are pitch-patch at best, and this is just intended to be an informal article, so please don’t expect a rigorous treatment. A quick bit of background – what does the Fourier transform do? The time domain representation (a series of evenly spaced samples over time)The frequency domain representation (the strength and phase of waves, at different frequencies, that can be used to reconstruct the signal)
Bayes' Theorem An Intuitive Explanation of Bayes' Theorem Bayes' Theorem for the curious and bewildered; an excruciatingly gentle introduction. Your friends and colleagues are talking about something called "Bayes' Theorem" or "Bayes' Rule", or something called Bayesian reasoning. They sound really enthusiastic about it, too, so you google and find a webpage about Bayes' Theorem and... It's this equation. That's all. So you came here. Why does a mathematical concept generate this strange enthusiasm in its students? Soon you will know. While there are a few existing online explanations of Bayes' Theorem, my experience with trying to introduce people to Bayesian reasoning is that the existing online explanations are too abstract. Or so they claim. And let's begin. Here's a story problem about a situation that doctors often encounter: What do you think the answer is? Next, suppose I told you that most doctors get the same wrong answer on this problem - usually, only around 15% of doctors get it right. E. E.
Pole of inaccessibility A pole of inaccessibility marks a location that is the most challenging to reach owing to its remoteness from geographical features that could provide access. Often it refers to the most distant point from the coastline. The term describes a geographic construct, not an actual physical phenomenon. Subject to varying definitions, it is of interest mostly to explorers. Northern pole of inaccessibility[edit] Northern pole of inaccessibility The northern pole of inaccessibility ( WikiMiniAtlas 84°03′N 174°51′W / 84.050°N 174.850°W / 84.050; -174.850 (Northern Pole of Inaccessibility)), sometimes known as the Arctic pole of inaccessibility, or just Arctic pole, is located on the Arctic Oceanpack ice at a distance farthest from any land mass. According to some reports, the first person to reach the spot on foot was Sir Wally Herbert, who arrived by dogsled in 1968. Southern pole of inaccessibility[edit] Southern pole of inaccessibility Oceanic pole of inaccessibility[edit] Eurasia[edit]
Are you smarter than a Hyena? « Laelaps Spotted Hyena (Crocuta crocuta), the “bad guys” of the African plains. My wife is repulsed by them, but I find something oddly intriguing about these predators; any social carnivore in which the female has a functioning pseudo-phallus nearly indistinguishable from the male’s is bound to stand out. Spotted Hyena are extremely effective, social predators, being much more effective hunters than many people think. The classic African battleground, at least in the mind of the public, features a pride of lions valiantly defending a kill from a pack of dastardly hyenas, laughing and yipping in a way that can only be described as disturbing. Just as likely as not, however, the favored lions are trying to steal prey killed by hyenas, both groups of carnivores vying for the top position in their habitats (cheetahs, wild dogs, leopards, and other smaller predators typically give up their kills to the more formidable lions and hyenas). But wait, there’s more! Like this: Like Loading...
Hyenas Cooperate, Problem-solve Better Than Primates Spotted hyenas may not be smarter than chimpanzees, but a new study shows that they outperform the primates on cooperative problem-solving tests. Captive pairs of spotted hyenas (Crocuta crocuta) that needed to tug two ropes in unison to earn a food reward cooperated successfully and learned the maneuvers quickly with no training. Experienced hyenas even helped inexperienced partners do the trick. When confronted with a similar task, chimpanzees and other primates often require extensive training and cooperation between individuals may not be easy, said Christine Drea, an evolutionary anthropologist at Duke University. Drea's research, published online in the October issue of Animal Behavior, shows that social carnivores like spotted hyenas that hunt in packs may be good models for investigating cooperative problem solving and the evolution of social intelligence. "No one wanted anything but primate cognition studies back then," Drea said. Drea and co-author Allisa N.
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