Links for February 2015

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Links for January 2015

  • There’s been some coverage of using etching to produce superhydrophobic metals. Unfortunately, it probably suffers from the same durability issues (no resistance to being destroyed through normal wear) as previous techniques that used special chemical coatings.
  • A funnel plot is a quick graphical way to check for publication bias on a topic.
  • Apparently, the best way to avoid a fight with a confrontational Red Kangaroo (the largest kangaroo species) is to give a deep cough. This is a signal of submission by subdominant males, and can assure the dominant male that you aren’t challenging him. Otherwise…

  • Daniel Dennett, synthesizing Anatol Rapoport, on how to compose a successful critical commentary:

    • You should attempt to re-express your target’s position so clearly, vividly, and fairly that your target says, “Thanks, I wish I’d thought of putting it that way.
    • You should list any points of agreement (especially if they are not matters of general or widespread agreement).
    • You should mention anything you have learned from your target.
    • Only then are you permitted to say so much as a word of rebuttal or criticism.

    If only the same code of conduct could be applied to critical commentary online, particularly to the indelible inferno of comments.

    But rather than a naively utopian, Pollyannaish approach to debate, Dennett points out this is actually a sound psychological strategy that accomplishes one key thing: It transforms your opponent into a more receptive audience for your criticism or dissent, which in turn helps advance the discussion.

    (H/t Rob Wiblin.) Although most folks have heard and approve of many of these tips, it’s common for people to get lazy about implementing them because, frankly, it’s kind of a lot of work.

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Links for December 2014

  • Steve Hsu notes that BGI has applied preimplantation genetic diagnosis (PGD) using next-generation sequencing techniques. Previous uses of PGD have only used simple screening methods, like searching for single-nucleotide polymorphisms, to avoid implanting embryos with a handful of well-understood genetic defects (which are then destroyed). Next generation methods have the potential to sequence most/all of the genome, allowing for traits influences by many genes to be selected for, like height and intelligence.
  • Crab housing exchange.
  • That the National Reconnaissance Office publicly releases the mission patches for their highly classified satellites is well-known on the internet, but I hadn’t realized that there was reason to think that classified details had been accidentally leaked through them in the past.
  • If correct, this is a surprisingly comprehensive and intuitive answer to many aspects of human bilateral (a)symmetry:

    Most of our asymmetry is due to just two organ systems: the GI tract and the heart. The concept that best explains the shape of both of these systems is the idea that a long organ that has to fit in a small body does so by being wound up.

    The heart could be composed of a linear arrangement of a pump, the lungs, and then a second pump. In some organisms like the worm, the heart is a linear pump. However the human body cannot accommodate a linear arrangement and thus we have what is effectively a tube curled up on itself.

    The GI tract is the same story. It would be hugely long if a linear, thus it has to be wound up inside of us. There is no symmetrical way to wind it up. Many organs like the pancreas and the liver actually bud off of the GI tract during development so the asymmetry of the GI tract explains the asymmetry of many of the other abdominal organs.

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Links for November 2014

Almost all the links this month are space related. I promise I spend time thinking about other things but…there’s just a lot of cool space-related links on the internet.

  • Video of the night sky with the stars stabilized so you can watch the ground spin around.
  • For several years the ESA worked on a spacecraft that would test the idea of deflecting a comet with a high-speed impactor. It was brilliantly named Don Quijote, with the rash impactor craft “Hidalgo” rushing in to the target with the observation craft “Sancho” watching from a safe distance. Unfortunately, it looks like the project stalled years ago, but a proposed joint NASA-ESA mission Asteroid Impact & Deflection Assessment (AIDA) could carry the torch [PDF] by targeting the asteroid 65803 Didymos. Didymos is actually a binary system, with a large primary asteroid and a smaller secondary asteroid orbiting it. When the impactor strikes the primary (speed ~ 6.25 km/s), it would induce perturbations to the orbit of the secondary observable from Earth. A 2019 launch and 2022 impact date have been chosen so that Didymos will be passing close to the Earth and the impact event will be visible to ground-based radar.
  • Half of all stars are not in galaxies?

    Astronomers have spotted a faint cosmic glow, unseen until now, that may come from stars that float adrift between galaxies. The discovery suggests that as many as half of all stars in the Universe lurk outside galactic boundaries….The stars were probably tossed there when galaxies collided.

    I don’t understand how this is still uncertain given our knowledge of galaxy and structure formation. But in any case, it’s interesting to note that the large majority (85%) of all the stars we see in the night sky are within 1,000 light years of Earth.

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Links for October 2014

  • Total moving face reconstruction“:

    We present an approach that takes a single video of a person’s face and reconstructs a high detail 3D shape for each video frame. We target videos taken under uncontrolled and uncalibrated imaging conditions, such as youtube videos of celebrities. In the heart of this work is a new dense 3D flow estimation method coupled with shape from shading. Unlike related works we do not assume availability of a blend shape model, nor require the person to participate in a training/capturing process. Instead we leverage the large amounts of photos that are available per individual in personal or internet photo collections. We show results for a variety of video sequences that include various lighting conditions, head poses, and facial expressions.

  • What’s changed since the days when theft was worse than murder? I would really love to see whether a “historical economist” (or whatever those are called) could estimate the statistical value of a human life as defined by people’s own revealed preferences. This is the sort of calculation where we infer how much each of us values our own lives based on the amount we are willing to pay to avoid small chances of death. In the US today, the number is about $8 million now, and is surprisingly consistent (within a factor of 2) over many possible inference methods. (Of course, there are exceptions where people effectively pay rates of many billion dollars per life to avoid emotionally salient risks, like terrorism.)

    The Nautilus article gives the misleading impression that society’s changing values are mostly due to moral progress (presumably arising, I guess, from people being persuaded by moral arguments, or from certain societal norms taking hold).

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Links for September 2014

  • In discussions about the dangers of increasing the prevalence of antibiotic-resistant bacteria by treating farm animals with antibotics, it’s a common (and understandable) misconception that antibiotics serve the same purpose with animals as for people: to prevent disease. In fact, antibiotics serve mainly as a way to increase animal growth. We know that this arises from the effect on bacteria (and not, say, by the effect of the antibiotic molecule on the animal’s cells), but it is not because antibiotics are reducing visible illness among animals:

    Studies conducted in germ free animals have shown that the actions of these AGP [antimicrobial growth promoters] substances are mediated through their antibacterial activity. There are four hypotheses to explain their effect (Butaye et al., 2003). These include: 1) antibiotics decrease the toxins produced by the bacteria; 2) nutrients may be protected against bacterial destruction; 3) increase in the absorption of nutrients due to a thinning of the intestinal wall; and 4) reduction in the incidence of sub clinical infections. However, no study has pinpointed the exact mechanism by which the AGP work in the animal intestine. [More.]

  • You’ve probably noticed that your brain will try to reconcile contradictory visual info. Showing different images to each eye will causes someone to essentially see only one or the other at a time (although it will switch back and forth). Various other optical illusions bring out the brain’s attempts to solve visual puzzles. But did you know the brain jointly reconciles visual info with audio info? Behold, the McGurk effect:

  • The much-hyped nanopore technique for DNA sequencing is starting to mature. Eventually this should dramatically lower the cost and difficulty of DNA sequencing in the field, but the technology is still buggy.

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Links for August 2014

  • Jester (Adam Falkowski) on physics breakthroughs:

    This year’s discoveries follow the well-known 5-stage Kübler-Ross pattern: 1) announcement, 2) excitement, 3) debunking, 4) confusion, 5) depression. While BICEP is approaching the end of the cycle, the sterile neutrino dark matter signal reported earlier this year is now entering stage 3.

  • The ultimate bounds on possible nuclides are more-or-less known from first principles.
  • UPower Technologies is a nuclear power start-up backed by Y-Combinator.
  • It is not often appreciated that “[s]mallpox eradication saved more than twice the number of people 20th century world peace would have achieved.” Malaria eradication would be much harder, but the current prospects are encouraging. Relatedly, the method for producing live but attenuated viruses is super neat:

    Attenuated vaccines can be made in several different ways. Some of the most common methods involve passing the disease-causing virus through a series of cell cultures or animal embryos (typically chick embryos). Using chick embryos as an example, the virus is grown in different embryos in a series. With each passage, the virus becomes better at replicating in chick cells, but loses its ability to replicate in human cells. A virus targeted for use in a vaccine may be grown through—“passaged” through—upwards of 200 different embryos or cell cultures. Eventually, the attenuated virus will be unable to replicate well (or at all) in human cells, and can be used in a vaccine. All of the methods that involve passing a virus through a non-human host produce a version of the virus that can still be recognized by the human immune system, but cannot replicate well in a human host.

    When the resulting vaccine virus is given to a human, it will be unable to replicate enough to cause illness, but will still provoke an immune response that can protect against future infection.

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