Thursday, April 17, 2008

The Raven

The Raven by Edgar Allan Poe, with beautiful illustrations by Gustave Doré at Project Gutenberg.

Elevators

Up and Then Down:The lives of elevators in the New Yorker Magazine.

Let's Beat Monty Hall to Death

There's a series of posts in the New York Times TiernyLab column about the famous Monty Hall problem: Is That a Fair Coin in Your Pocket?.
Partition–Edit–Count: Naive Extensional Reasoning in Judgment of Conditional Probability

Fog of War

The Fog of War the 2003 documentary about Robert S. McNamara, the secretary of defence under Kennedy/Johnson by director Erroll Morris. The film was made before 9/11 and the current Iraq war, but there are eerie similiaries.

Wednesday, April 16, 2008

Gardner Gathering

Penn and Teller hang out with magicians and mathematicians at a Gardner Gathering - meetings held in honor of the writer Martin Gardner.

Number Gossip

Number Gossip
Number Gossip: Plug in your number!

Find out which number is: composite, deficient, even, odious, palindromic, powerful, practical ...

The Tudors / Sweating Sickness

I've been watching the Showtime series The Tudors on DVD. It started out 'ok' but become more engrossing as it went on. Unfortunately, I made the mistake of looking up the historical figures in Wikipedia and found there were major historical inaccuracies in the show, which I found distracting. I should have waited until finishing the show!
The show mentions a devasting epidemic of "sweating sickness" in England at the time. I assumed that was another term for the bubonic plague, but apparently it's a completely different disease. The exact nature of the sweating sickness is still unknown.

The Early Universe

Let there be Light: the Emergence of Structure out of the Dark Ages in the Early Universe
The initial conditions of our Universe can be summarized on a single sheet of paper. Yet the Universe is full of complex structures today, such as stars, galaxies and groups of galaxies. In this review I describe the standard theoretical model for how complexity emerged from the simple initial state of the Universe at early cosmic times through the action of gravity. In order to test and inform the related theoretical calculations, large-aperture telescopes and arrays of radio antennae are currently being designed and constructed. The actual transition from simplicity to complexity has not been observed as of yet. The simple initial conditions were already traced in maps of the microwave background radiation, but the challenge of detecting the first generation of galaxies defines one of the exciting frontiers in the future of cosmology. Once at hand, the missing images of the infant Universe might potentially surprise us and revise our current ideas.

Polarisation vision

The secret world of shrimps: polarisation vision at its best
New Form of Vision Discovered

Monday, April 14, 2008

Earth Rise


This image is a still from a high-definition April 5, 2007 video of the Earth rising above the moon as seen by Japan's Kaguya lunar orbiter. The probe was about 236,121 miles (380,000 km) away from Earth at the time. Credit: JAXA/NHK.
High Resolution Video

John A. Wheeler Dies

John A. Wheeler, Physicist Who Coined the Term ‘Black Hole,’ Is Dead at 96 article in the New York Times.

Gecko Acrobatics

Active tails enhance arboreal acrobatics in geckos in PNAS.
Geckos are nature's elite climbers. Their remarkable climbing feats have been attributed to specialized feet with hairy toes that uncurl and peel in milliseconds. Here, we report that the secret to the gecko's arboreal acrobatics includes an active tail. We examine the tail's role during rapid climbing, aerial descent, and gliding. We show that a gecko's tail functions as an emergency fifth leg to prevent falling during rapid climbing. A response initiated by slipping causes the tail tip to push against the vertical surface, thereby preventing pitch-back of the head and upper body. When pitch-back cannot be prevented, geckos avoid falling by placing their tail in a posture similar to a bicycle's kickstand. Should a gecko fall with its back to the ground, a swing of its tail induces the most rapid, zero-angular momentum air-righting response yet measured. Once righted to a sprawled gliding posture, circular tail movements control yaw and pitch as the gecko descends. Our results suggest that large, active tails can function as effective control appendages. These results have provided biological inspiration for the design of an active tail on a climbing robot, and we anticipate their use in small, unmanned gliding vehicles and multisegment spacecraft.

Asian-American Birth Gender Bias

Son-biased sex ratios in the 2000 United States Census in PNAS.
We document male-biased sex ratios among U.S.-born children of Chinese, Korean, and Asian Indian parents in the 2000 U.S. Census. This male bias is particularly evident for third children: If there was no previous son, sons outnumbered daughters by 50%. By contrast, the sex ratios of eldest and younger children with an older brother were both within the range of the biologically normal, as were White offspring sex ratios (irrespective of the elder siblings' sex). We interpret the found deviation in favor of sons to be evidence of sex selection, most likely at the prenatal stage

Let's Not Have a Nuclear War, OK?


Total ozone deviations following 5-Tg soot injection in the upper troposphere.
http://www.pnas.org/cgi/content/full/105/14/5283
Atmospheric consequences of nuclear exchange Nuclear winter has been hypothesized to dramatically alter the Earth's climate. Michael Mills et al. have studied ozone depletion as a result of regional nuclear war, developing a computational model that links climate to atmospheric chemistry, and conducting 10-year simulations. The fires that would result from a total exchange of 100 Hiroshima-equivalent nuclear devices (yield 15 kilotons) would generate 5 million tonnes of soot that firestorms and solar heating would loft into the stratosphere. At altitudes up to 60 km, the soot would absorb solar radiation and heat surrounding gases, thus increasing the rate constants for several reactions that break down ozone. The authors found that two chemical reactions in particular would dominate alterations in ozone after a nuclear war: (i) the Chapman cycle, in which an oxygen free radical and ozone combine to form two diatomic molecules; and (ii) a coupled pair of reactions catalyzed by NO and NO2 that similarly produces diatomic oxygen. In the year after a nuclear war, the Chapman cycle would account for the greatest ozone loss, but NOx catalysis would then become dominant and persist for several more years. Mills et al.'s model predicts that the net result in both hemispheres would be an ozone hole extending from 20° north or south latitude to the poles. — K.M.

Massive global ozone loss predicted following regional nuclear conflict in PNAS.
We use a chemistry-climate model and new estimates of smoke produced by fires in contemporary cities to calculate the impact on stratospheric ozone of a regional nuclear war between developing nuclear states involving 100 Hiroshima-size bombs exploded in cities in the northern subtropics. We find column ozone losses in excess of 20% globally, 25–45% at midlatitudes, and 50–70% at northern high latitudes persisting for 5 years, with substantial losses continuing for 5 additional years. Column ozone amounts remain near or <220 Dobson units at all latitudes even after three years, constituting an extratropical "ozone hole." The resulting increases in UV radiation could impact the biota significantly, including serious consequences for human health. The primary cause for the dramatic and persistent ozone depletion is heating of the stratosphere by smoke, which strongly absorbs solar radiation. The smoke-laden air rises to the upper stratosphere, where removal mechanisms are slow, so that much of the stratosphere is ultimately heated by the localized smoke injections. Higher stratospheric temperatures accelerate catalytic reaction cycles, particularly those of odd-nitrogen, which destroy ozone. In addition, the strong convection created by rising smoke plumes alters the stratospheric circulation, redistributing ozone and the sources of ozone-depleting gases, including N2O and chlorofluorocarbons. The ozone losses predicted here are significantly greater than previous "nuclear winter/UV spring" calculations, which did not adequately represent stratospheric plume rise. Our results point to previously unrecognized mechanisms for stratospheric ozone depletion.

Is the Solar System Stable?

On the Dynamical Stability of the Solar System
The experiments yielded one evolution in which Mercury falls onto the Sun at ~1.261Gyr from now, and another in which Mercury and Venus collide in ~862Myr. In the latter solution, as a result of Mercury's unstable behavior, Mars was ejected from the Solar System at ~822Myr. We have performed a number of numerical tests that confirm these results, and indicate that they are not numerical artifacts.

What is a Galaxy?

What is a galaxy? How Cold is Cold Dark Matter? Recent progress in Near Field Cosmology
These data show that there is a bimodal distribution in half-light radii, with stable star clusters always being smaller than 35pc, while stable galaxies are always larger than 120pc. We extend the previously known observational relationships and interpret them in terms of a more fundamental pair of intrinsic properties of dark matter itself: dark matter forms cored mass distributions, with a core scale length of greater than about 100pc, and always has a maximum central mass density with a narrow range.
...
Galaxies are embedded in dark matter halos with these properties; smaller systems containing dark matter are not observed

SS433

SS433 a strange object in our own Galaxy. Aligned Molecular Clouds towards SS433 and L=348.5 degrees; Possible Evidence for Galactic "Vapor Trail" Created by Relativistic Jet

High speed cameras

Nice "slow-motion" videos on the site Vision Research.

Thursday, April 10, 2008

Bridge Technology

Super-Bridges Suspended Over Carbon Nanotube Cables
In this paper the new concept of super-bridges, i.e. kilometre-long bridges suspended over carbon nanotube cables, is introduced. The analysis shows that the use of realistic (thus defective) carbon nanotube bundles as suspension cables can enlarge the current limit main span by a factor of 3.

Sunday, April 06, 2008

What is the reason for Menopause?

Reproductive conflict and the separation of reproductive generations in humans in PNAS.
An enduring puzzle of human life history is why women cease reproduction midway through life. Selection can favor postreproductive survival because older females can help their offspring to reproduce. But the kin-selected fitness gains of helping appear insufficient to outweigh the potential benefits of continued reproduction. Why then do women cease reproduction in the first place? Here, we suggest that early reproductive cessation in humans is the outcome of reproductive competition between generations, and we present a simple candidate model of how this competition will be resolved. We show that among primates exhibiting a postreproductive life span, humans exhibit an extraordinarily low degree of reproductive overlap between generations. The rapid senescence of the human female reproductive system coincides with the age at which, in natural fertility populations, women are expected to encounter reproductive competition from breeding females of the next generation. Several lines of evidence suggest that in ancestral hominids, this younger generation typically comprised immigrant females. In these circumstances, relatedness asymmetries within families are predicted to give younger females a decisive advantage in reproductive conflict with older females. A model incorporating both the costs of reproductive competition and the benefits of grandmothering can account for the timing of reproductive cessation in humans and so offers an improved understanding of the evolution of menopause.

aMazing Lock


Chain style Doorlock forces you to solve a maze to exit
100% Titanium Alloy Construction

Friday, April 04, 2008

Very Hard, I would imagine

In the Wall Street Journal today: UBS Shares Rally on Breakup Push
By CARRICK MOLLENKAMP and KATHARINA BART

The article discusses UBS, a Swiss Bank that's been having problems recently
"It's hard to make a case to someone wealthy that you can manage their money well when you've just lost $37 billion yourself," said Dirk Hoffmann-Becking, an analyst at Bernstein Research in London.

Are Neutrinos their own antiparticles?

ARE NEUTRINOS MAJORANA PARTICLES?
Photons are their own antiparticles, could that be true of neutrinos as well? There is an experiment which can tell - neutrinoless double beta decay. Unfortunately this is a difficult experiment.

Nanowriting

Floating Tip Nanolithography
We demonstrate noncontact, high quality surface modification with spatial resolution of ~20 nm. The nanowriting is based on the interaction between the surface and the tip of an Atomic force microscope illuminated by a focused laser beam and hovering 1-4 nanometers above the surface without touching it. The floating tip nanowriting is compared to mechanical surface scratching, and is found to be much more reproducible, and of higher quality. In an Apertureless Scanning Near Field Optical Microscope geometry the tip is illuminated by a focused femtosecond laser, leading to two different, clearly identifiable mechanisms for removing material from the surface: when heated by the laser beam, the hot-tip thermally patterns the surface of low melting temperature soft materials, and when focused right at the apex of the sharp tip, the enhanced electric field of the laser beam causes ablation in high melting temperature metal films.

Thursday, April 03, 2008

Einstein's Relativity Song


The date it was posted on Youtube - April 1.

Wednesday, April 02, 2008

The Safest Rest You've Ever Had

The Quantum Sleeper
The Quantum Sleeper Unit is a high-level security system designed for maximum protection in various hostile environments

On Haircuts

No Country for Old Men with Javier Bardem as Anton Chigurh:
Chigurh's distinctive look was derived from a 1979 photo from a book supplied by Tommy Lee Jones which featured photos of brothel patrons on the Texas-Mexico border.[33] Describing his "extraordinary moptop haircut," he said, "You don't have to act the haircut. The haircut acts by itself."


Sensitive Optical Measurements

Beating the standard quantum limit: Phase super-sensitivity of N-photon interferometers
Quantum metrology promises greater sensitivity for optical phase measurements than could ever be achieved classically

Quantum enhancement of N-photon phase sensitivity by interferometric addition of down-converted photon pairs to weak coherent light

Quantum Heat Engines

Coherent Power Booster in Science Magazine.
According to the Second Law of Thermodynamics, a heat engine requires two heat baths to operate-a warm source of heat and a cooler dump for waste heat. In apparent violation of this law, Scully et al. propose a heat engine that uses quantum coherence to extract work from a single, warm gas. In his Perspective, Linke explains that the Second Law is not violated, because the power extracted from the bath is smaller than that required to achieve coherence. By combining quantum mechanics with traditional heat engines, the efficiencies of various kinds of motors could be enhanced.


Improving Carnot efficiency with quantum correlations

Tuesday, April 01, 2008

Was There a Big Bang?

Was There A Big Bang?
The big bang hypothesis is widely accepted despite numerous physics conflicts. It rests upon two experimental supports, galactic red shift and the cosmic microwave background. Both are produced by dark matter, shown here to be hydrogen dominated aggregates with a few percent of helium nodules. Scattering from these non-radiating intergalactic masses produce a red shift that normally correlates with distance. Warmed by our galaxy to an Eigenvalue of 2.735 K, drawn near the Earth, these bodies, kept cold by ablation, resonance radiate the Planckian microwave signal. Several tests are proposed that will distinguish between this model and the big bang.