Cenotes

I've just done a couple of dives at cenotes (sinkholes) in the Yucatan peninsula of Mexico. My favorite so far is Dos Ojos - extremely clear water, beautiful light, nice cave formations.

Carbon Tubes and Ribbons

Carbon nanoelectronics: unzipping tubes into graphene ribbons

We report on the transport properties of novel carbon nanostructures made of partially unzipped carbon nanotubes, which can be regarded as a seamless junction of a tube and a nanoribbon. We find that graphene nanoribbons act at certain energy ranges as a perfect valley filters for carbon nanotubes, with the maximum possible conductance. Our results show that a partially unzipped carbon nanotube is a magnetoresistive device, with a very large value of the magnetoresistance. We explore the properties of several structures combining nanotubes and graphene nanoribbons, demonstrating that they behave as optimal contacts for each other, and opening a new route for the design of mixed graphene/nanotube devices.

an extraordinary flare in the M87 jet

Hubble Space Telescope observations of an extraordinary flare in the M87 jet

HST-1, a knot along the M87 jet located 0.85 arcsec from the nucleus of the galaxy has experienced dramatic and unexpected flaring activity since early 2000. We present analysis of Hubble Space Telescope Near-Ultraviolet (NUV) imaging of the M87 jet from 1999 May to 2006 December that reveals that the NUV intensity of HST-1 has increased 90 times over its quiescent level and outshines the core of the galaxy. The NUV light curve that we derive is synchronous with the light curves derived in other wavebands. The correlation of X-ray and NUV light curves during the HST-1 flare confirms the synchrotron origin of the X-ray emission in the M87 jet. The outburst observed in HST-1 is at odds with the common definition of AGN variability usually linked to blazars and originating in close proximity of the central black hole. In fact, the M87 jet is not aligned with our line of sight and HST-1 is located at one million Schwarzchild radii from the super-massive black hole in the core of the galaxy.

Manta Rays

I've just returned from a wonderful experience with the Manta rays of San Benedicto Island, in the Pacific off the coast of Mexico. Thanks to Gregory Colbert, his film crew and friends, and the crew of the Nautilus Explorer for an amazing trip.

Thermodynanics from Quantum Mechanics

Origin of the Canonical Ensemble: Thermalization with Decoherence

It is shown that a system embedded in a closed quantum mechanical system relaxes to its canonical ensemble equilibrium state if the environment drives this system to a fully decoherent state and the excess energy can release from the system to the environment or backward. Our findings show that the canonical ensemble is a special state that may result from pure quantum dynamics, suggesting that quantum mechanics may be regarded as the foundation of quantum statistical mechanics

Statistical mechanics is one of cornerstones of modern physics but its foundations and basic postulates are still under debate [1, 2, 3, 4]. There is a common believe that a generic “system” that interacts with a generic environment evolves into a state described by the canonical ensemble. Experience shows that this is true but a detailed understanding of this process, which is crucial for a rigorous justification of statistical physics and thermodynamics, is still lacking.

Classical to quantum transition

Classical to quantum transition of a driven nonlinear nanomechanical resonator

Much experimental effort is invested these days in fabricating nanoelectromechanical systems (NEMS) that are sufficiently small, cold, and clean, so as to approach quantum mechanical behavior as their typical quantum energy scale $\hbar\Omega$ becomes comparable to that of the ambient thermal energy $k_{B}T$. Such systems will hopefully enable one to observe the quantum behavior of human-made objects, and test some of the basic principles of quantum mechanics. Here we expand and elaborate on our recent suggestion [PRL 99 (2007) 040404] to exploit the nonlinear nature of a nanoresonator in order to observe its transition into the quantum regime. We study this transition for an isolated resonator, as well as one that is coupled to a heat bath at either zero or finite temperature. We argue that by exploiting nonlinearities, quantum dynamics can be probed using technology that is almost within reach. Numerical solutions of the equations of motion display the first quantum corrections to classical dynamics that appear as the classical-to-quantum transition occurs. This provides practical signatures to look for in future experiments with NEMS resonators.

An empirical Gravity law up to galactic scales

An empirical Gravity law up to galactic scales

Modelling on the MOND proposal, we introduce an empirically motivated gravity law for galactic and sub-galactic scales. This, circumvents the need for the cumbersome and ill-defined transition regime which exists in MOND, when passing from the standard gravitational regime at high accelerations to the MOND regime at low accelerations. We show that the proposed force law does not violate dynamical constraints at sub-galactic and solar system scales, does not degrade the good fit of the MOND proposal at large galactic scales, and in fact, slightly improves the accordance with observations at dSph scales. The proposed gravity law hence yields a good description of gravitational phenomena from terrestrial to large galactic scales, within a unique framework, without the need to invoke the presence of the still undetected and hypothetically dominant dark matter. Isothermal equilibrium density profiles then yield projected surface density profiles for the local dSph galaxies in very good agreement with observational determinations, for values of the relevant parameters as inferred from recent observations of these Galactic satellites. The observed scaling relations for these systems are also naturally accounted for within the proposed scheme.

The Origin of Labor Division

In Bert Hölldobler, E.O. Wilson: "The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies", p39.

... solitary bees behave like semisocial species when forced forced together experimentally. ... the coerced partners proceed variously to divide labor in foraging, tunneling and guarding. ... The division of labor appears to be the result of a preexisting behavioral groundplan in which solitary individuals tend to move from one job to another after the first is completed. In eusocial special, the algorithm is transferred to the avoidance of a job already being filled by another nestmate. It is evident that progressively providing bees and wasps are already "spring loaded" for a rapid shift to eusociality once ecological factors favor the change.

Flying Micro Robot

UW researchers develop world's first flying microrobot for microscale applications it flys using magnetic levitation.
Credit: University of Waterloo

Nothing to Be Frightened Of

The first chapter of Nothing to Be Frightened Of by Julian Barnes.
The exchange below is between Barnes and his brother, they are discussing their neice C. and her boyfriend R.

Instead, I asked, "But you approve of R.?"

"It's irrelevant," my brother replied, "whether or not I approve of R."

"No, it's not. C. might want you to approve of him."

"On the contrary, she might want me not to approve of him."

"But either way, it's not irrelevant to her whether or not you approve or disapprove."

He thought this over for a moment. "You're right," he said.

You can perhaps tell from these exchanges that he is the elder brother.

Mapa de Cuauhtinchan No. 2

A Lost World on the Map a review of
Cave, City, and Eagle's Nest: An Interpretive Journey Through the Mapa de Cuauhtinchan No. 2
edited by Davíd Carrasco and Scott Sessions
University of New Mexico Press, 479 pp., $65.00
The indigenous map is from the sixteenth century Valley of Puebla in Mexico.

Measuring measurement

Measuring measurement

Measurement connects the world of quantum phenomena to the world of classical events. It plays both a passive role, observing quantum systems, and an active one, preparing quantum states and controlling them. Surprisingly - in the light of the central status of measurement in quantum mechanics - there is no general recipe for designing a detector that measures a given observable. Compounding this, the characterization of existing detectors is typically based on partial calibrations or elaborate models. Thus, experimental specification (i.e. tomography) of a detector is of fundamental and practical importance. Here, we present the realization of quantum detector tomography: we identify the optimal positive-operator-valued measure describing the detector, with no ancillary assumptions. This result completes the triad, state, process, and detector tomography, required to fully specify an experiment. We characterize an avalanche photodiode and a photon number resolving detector capable of detecting up to eight photons. This creates a new set of tools for accurately detecting and preparing non-classical light.

The Strong CP Problem

CP Violation occurs in weak but not strong nuclear reactions. Why? In theory, there could be a nonzero CP violating angle theta, but experimentally it is zero. One way that shows up is the neutron electron dipole moment, which is also zero experimentally. One possible explanation is a new particle, the axion.

Coronal Heating Problem

The temperature at surface of the sun is about 5800K, but the temperature of solar corona is millions of degrees kelvin. Why is the corona so hot? We don't yet know.
a solar coronal loop
The corona is a source for solar storms, in particular coronal mass ejections. The most powerful such storm on record was the solar storm of 1859.
Currently the sun is unusually quiet: Deep Solar Minimum.

Garbage Land

Garbage Land by Elizabeth Royte recounts the author's attempt to track the destiny of her household garbage and sewage.

The Bear Stearns Meltdown

I'm also reading House of Cards: A Tale of Hubris and Wretched Excess on Wall Street, about the Bear Stearns meltdown.

"when involved in a trade, look around the room and determine who the chump is and if the chump is not clear to you, assume it is YOU."

"So as an example, if a salesman and trader are talking about how they did a trade with a customer and they think there's a significant business opportunity that came of that trade, at Bear Stearns they might say, 'I just ripped that fucker's head off. I'm going to make a lot of money on this trade. That's fucking crazy.' But at Goldman Sachs a salesman and a trader would talk about, 'That's a great opportunity. That was a very attractive and commercial price you purchased those securities at and I think we'll have a very interesting economic opportunity in the near future.'

Whales Battle on the Silver Bank

There was a spectactular battle between two humpback whales on the Silver Bank this year (2009) here are the photographs.

The Baseline Scenario

The Baseline Scenario is a blog about the current global financial crisis, written by Simon Johnson and James Kwak. Here a couple of their other recent articles.
The Radicalization of Ben Bernanke in the Washington Post.
He is throwing trillions of dollars at the financial crisis. What happens if his gambles don't pay off?
The Quiet Coup in the Atlantic.

The crash has laid bare many unpleasant truths about the United States. One of the most alarming, says a former chief economist of the International Monetary Fund, is that the finance industry has effectively captured our government—a state of affairs that more typically describes emerging markets, and is at the center of many emerging-market crises. If the IMF’s staff could speak freely about the U.S., it would tell us what it tells all countries in this situation: recovery will fail unless we break the financial oligarchy that is blocking essential reform. And if we are to prevent a true depression, we’re running out of time.

The Global Oceanic Conveyer Belt

There's a nice simplifed explanation of global thermohaline ocean circulation at Oceanic Conveyer Belt. The rest of the site nicely explains other aspects of "ocean motion".

Social Motives for Syntax

Social Motives for Syntax in Science.
Book review of Origins of Human Communication by Michael Tomasello,
MIT Press, Cambridge, MA, 2008. 407 pp. $36, £23.95. ISBN 9780262201773.

Summary: Tomasello argues for the importance of social interactions in an evolutionary transformation from pointing and pantomiming to human vocal communication.

On the Origin of Flowering Plants

On the Origin of Flowering Plants

Summary: Which plant was the mother of all angiosperms? In the fourth essay in Science's series in honor of the Year of Darwin, Elizabeth Pennisi discusses efforts to answer Darwin's question about how flowering plants diversified and spread so rapidly across the globe.

Sleeping to Reset Overstimulated Synapses

Sleeping to Reset Overstimulated Synapses in Science.

Summary: In this week's issue of Science (pp. 105 and 109), two studies with fruit flies provide what some researchers say is the most compelling evidence to date for the provocative hypothesis that sleep dials down synapses that have been cranked up by a day's worth of neural activity, helping to conserve both energy and precious real estate in the brain.

The North Atlantic Oscillation and Medieval Climate

Persistent Positive North Atlantic Oscillation Mode Dominated the Medieval Climate Anomaly in Science.

The Medieval Climate Anomaly (MCA) was the most recent pre-industrial era warm interval of European climate, yet its driving mechanisms remain uncertain. We present here a 947-year-long multidecadal North Atlantic Oscillation (NAO) reconstruction and find a persistent positive NAO during the MCA. Supplementary reconstructions based on climate model results and proxy data indicate a clear shift to weaker NAO conditions into the Little Ice Age (LIA). Globally distributed proxy data suggest that this NAO shift is one aspect of a global MCA-LIA climate transition that probably was coupled to prevailing La Niña–like conditions amplified by an intensified Atlantic meridional overturning circulation during the MCA.

Exploring the Quantum Vacuum with Lasers

Quantum Vacuum Experiments Using High Intensity Lasers

The quantum vacuum constitutes a fascinating medium of study, in particular since near-future laser facilities will be able to probe the nonlinear nature of this vacuum. There has been a large number of proposed tests of the low-energy, high intensity regime of quantum electrodynamics (QED) where the nonlinear aspects of the electromagnetic vacuum comes into play, and we will here give a short description of some of these. Such studies can shed light, not only on the validity of QED, but also on certain aspects of nonperturbative effects, and thus also give insights for quantum field theories in general.

A Solar Twin?

High-Dispersion Spectroscopic Study of Solar Twins: HIP 56948, HIP 79672, and HIP 100963

An intensive spectroscopic study was performed for three representative solar twins (HIP 56948, HIP 79672, and HIP 100963) as well as for the Sun (Moon; reference standard), with an intention of (1) quantitatively discussing the relative-to-Sun similarities based on the precisely established differential parameters and (2) investigating the reason causing the Li abundance differences despite their similarities. It was concluded that HIP 56948 most resembles the Sun in every respect including the Li abundance (though not perfectly similar) among the three and deserves the name of "closest-ever solar twin", while HIP 79672 and HIP 100963 have somewhat higher effective temperature and appreciably higher surface Li composition. While there is an indication of Li being rotation-dependent because the projected rotation in HIP 56948 (and the Sun) is slightly lower than the other two, the rotational difference alone does not seem to be so large as to efficiently produce the marked change in Li. Rather, this may be more likely to be attributed (at least partly) to the slight difference in T_eff via some T_eff-sensitive Li-controlling mechanism. Since the abundance of beryllium was found to be essentially solar for all stars irrespective of Li, any physical process causing the Li diversity should work only on Li without affecting Be.

See also Age and mass of solar twins constrained by lithium abundance

Neutron Stars

The Behavior of Matter under Extreme Conditions

The cores of neutron stars harbor the highest matter densities known to occur in nature, up to several times the densities in atomic nuclei. Similarly, magnetic field strengths can exceed the strongest fields generated in terrestrial laboratories by ten orders of magnitude. Hyperon-dominated matter, deconfined quark matter, superfluidity, even superconductivity are predicted in neutron stars. Similarly, quantum electrodynamics predicts that in strong magnetic fields the vacuum becomes birefringent. The properties of matter under such conditions is governed by Quantum Chromodynamics (QCD) and Quantum Electrodynamics (QED), and the close study of the properties of neutron stars offers the unique opportunity to test and explore the richness of QCD and QED in a regime that is utterly beyond the reach of terrestrial experiments. Experimentally, this is almost virgin territory.

Local Void vs Dark Energy

Local Void vs Dark Energy: Confrontation with WMAP and Type Ia Supernovae

It is now a known fact that if we happen to be living in the middle of a large underdense region, then we will observe an "apparent acceleration", even when any form of dark energy is absent. In this paper, we present a "Minimal Void" scenario, i.e. a "void" with minimal underdensity contrast (of about -0.4) and radius (~ 200-250 Mpc/h) that can, not only explain the supernovae data, but also be consistent with the 3-yr WMAP data. We also discuss consistency of our model with various other measurements such as Big Bang Nucleosynthesis, Baryon Acoustic Oscillations and local measurements of the Hubble parameter, and also point out possible observable signatures.

Antimatter Annihilation Anomalies

PAMELA and other experiments are searching for antimatter annihilation, as possible evidence for Dark Matter and other astrophysical phenomenon. These experiments have observed excess positron annihilation, but not antiprotons, which is inconsistent with many popular Dark Matter models. See also Dark Matter Annihilation and the PAMELA and ATIC Anomaly and Discriminate different scenarios to account for the PAMELA and ATIC data by synchrotron and IC radiation and Is the PAMELA anomaly caused by the supernova explosions near the Earth?
See also A hint of dark matter? in Nature.

Cosmic ray positrons are known to be produced in interactions in the interstellar medium. As well as originating from this 'secondary source', positrons might also be generated in primary sources such as pulsars and microquasars — or by dark matter annihilation. A new measurement of the positron fraction in the cosmic radiation for the energy range 1.5–100 GeV has been made using data from the PAMELA satellite experiment. Previous measurements, made predominantly by balloon-borne instruments, yield a positron fraction compatible with 'secondary source' production from interactions between cosmic ray nuclei and interstellar matter. Above 10 GeV the new measurements deviate significantly from this expectation, pointing to the presence of a primary source, either a nearby astrophysical object or dark matter particle annihilations.

The cosmic ray lepton puzzle in the light of cosmological N-body simulations

The PAMELA and ATIC collaborations have recently reported an excess in the cosmic ray positron and electron fluxes. These lepton anomalies might be related to cold dark matter (CDM) particles annihilating within a nearby dark matter clump. We outline regions of the parameter space for both the dark matter subhalo and particle model, where data from the different experiments are reproduced. We then confront this interpretation of the data with the results of the cosmological N-body simulation Via Lactea II. Having a sizable clump (Vmax = 9km/s) at a distance of only 1.2 kpc could explain the PAMELA excess, but such a configuration has a probability of only 0.37 percent. Reproducing also the ATIC bump would require a very large, nearby subhalo, which is extremely unlikely (p~3.10^-5). In either case, we predict Fermi will detect the gamma-ray emission from the subhalo. We conclude that under canonical assumptions, the cosmic ray lepton anomalies are unlikely to originate from a nearby CDM subhalo.

Radio Emissions from the Center of the Milky Way

Modeling Emission from the Supermassive Black Hole in the Galactic Center with GRMHD Simulations

Sagittarius A* is a compact radio source at the Galactic center, powered by accretion of fully ionized plasmas into a supermassive black hole. However, the radio emission cannot be produced through the thermal synchrotron process by a gravitationally bounded flow. General relativistic magneto-hydrodynamical(GRMHD) simulations of black hole accretion show that there are strong unbounded outflows along the accretion. With the flow structure around the black hole given by GRMHD simulations, we investigate whether thermal synchrotron emission from these outflows may account for the observed radio emission. We find that simulations producing relatively high values of plasma beta cannot produce the radio flux level without exceeding the X-ray upper limit set by Chandra observations through the bremsstrahlung process. The predicted radio spectrum is also harder than the observed spectrum both for the one temperature thermal model and a simple nonthermal model with a single power-law electron distribution. The electron temperature needs to be lower than the gas temperature near the black hole to reproduce the observed radio spectrum. A more complete modeling of the radiation processes, including the general relativistic effects and transfer of polarized radiation, will give more quantitative constraints on physical processes in Sgr A* with the current multi-wavelength, multi-epoch, and polarimetric observations of this source.

The Origin of Galaxies

Early assembly of the most massive galaxies

The current consensus is that galaxies begin as small density fluctuations in the early Universe and grow by in situ star formation and hierarchical merging. Stars begin to form relatively quickly in sub-galactic sized building blocks called haloes which are subsequently assembled into galaxies. However, exactly when this assembly takes place is a matter of some debate. Here we report that the stellar masses of brightest cluster galaxies, which are the most luminous objects emitting stellar light, some 9 billion years ago are not significantly different from their stellar masses today. Brightest cluster galaxies are almost fully assembled 4-5 Gyrs after the Big Bang, having grown to more than 90% of their final stellar mass by this time. Our data conflict with the most recent galaxy formation models based on the largest simulations of dark matter halo development. These models predict protracted formation of brightest cluster galaxies over a Hubble time, with only 22% of the stellar mass assembled at the epoch probed by our sample. Our findings suggest a new picture in which brightest cluster galaxies experience an early period of rapid growth rather than prolonged hierarchical assembly.

An Unusual Galaxy Cluster

Galaxy Zoo: an unusual new class of galaxy cluster

Thanks to the visual inspection of SDSS images afforded by the Galaxy Zoo project, we have identified a new class of galaxy clusters which possess number of unusual properties. These clusters are unusually elongated, possess young and highly dynamic galaxy populations, and most unexpectedly, present neatly typeset, leftjustified, messages written in the English language. One interpretation for the existence of these galaxy clusters is as conclusive evidence for intelligent life elsewhere in the universe. Conversely, however, they could indicate that many phenomena usually attributed to intelligent life on Earth actually occur spontaneously, without any thought necessarily being involved at all.

Pliocene Warm Period

Greatly Expanded Tropical Warm Pool and Weakened Hadley Circulation in the Early Pliocene in Science.

The Pliocene warm interval has been difficult to explain. We reconstructed the latitudinal distribution of sea surface temperature around 4 million years ago, during the early Pliocene. Our reconstruction shows that the meridional temperature gradient between the equator and subtropics was greatly reduced, implying a vast poleward expansion of the ocean tropical warm pool. Corroborating evidence indicates that the Pacific temperature contrast between the equator and 32°N has evolved from 2°C 4 million years ago to 8°C today. The meridional warm pool expansion evidently had enormous impacts on the Pliocene climate, including a slowdown of the atmospheric Hadley circulation and El Niño–like conditions in the equatorial region. Ultimately, sustaining a climate state with weak tropical sea surface temperature gradients may require additional mechanisms of ocean heat uptake (such as enhanced ocean vertical mixing).

Orbital resonance and Solar cycles

Orbital resonance and Solar cycles
A detailed analysis of the couplings between the orbits of the planets and possible relationships with solar activity and the earth's climate. Nice graphics.

Is the Milky Way "Rotation Curve" Real?

Indications of an Unmodelled Component in Spectrographic Measurements of Local Stars
The Milky Way's rotation curve appears to be flat, based on the measured doppler shifts of interstellar gas. In contrast, the authors find that the rotation curve of the motions of local stars is not flat. Is the explanation an unmodelled component to the spectrographic measurements?

Solar System Dark Matter

Solar System Dark Matter by Stephen L. Adler:

I review constraints on solar system-bound dark matter, and discuss the possibility that dark matter could be gravitationally bound to the earth and other planets. I briefly survey various empirical constraints on such planet-bound dark matter, and discuss effects it could produce if present, including anomalous planetary heating and flyby velocity changes

Whales and Dolphins, Oh My

In addition to Humpback Whales, we sometimes see pods of small (~4 ft) Spotted Dolphins here on the Silver Bank (in the Dominican Republic). The two species sometimes interact: the dolphins "tease" the whales, often mothers with calves. The dolphins dart in and out, and the humpbacks typically respond by slapping the water with their long pectoral fins along with other apparently agitated behaviours, seemingly trying to get the dolphins to leave them alone. This week we observed a completely different and suprising interaction.

We found a male juvenile whale (~20 feet long, perhaps 3 years old) logging on the surface. We put people in the water and he swam right up to everyone several times, very nice and easy. At some point 20 spotted dolphins appeared and the juvenile started slashing away at them, behaviour we normally expect to see. But after a few minutes Lorenzo Martinez - a Dominican whale expert and National Park official -remarked that the juvy (whale) was actually following the dolphins. The young whale followed the dolphins for perhaps 4-5 miles. Whenever we couldn't find the juvy, we would just look for dolphins, go to them and the juvy would show up. Toward the end, Captain Denise Lawrence put us in the water just as the the pod of dolphins was approaching our tender. I saw 10-15 scattered dolphins go by, then five dolphins in a tight pack, followed immediately by the juvenile humpback whale.

Shortly afterwards, this remarkable inter-species interaction ended. A mother, calf and their adult male escort swam nearby. Our juvenile whale attempted to join the group, but the escort manuvered between the juvenile and the mother and calf, rolled onto his side and repeatedly slammed the water with his tremendous pectoral fin, warning the juvenile to stay away.

Tom Conlin, whale naturalist and our host on the Silver Bank, has been observing the humpbacks and dolphins here for nineteen years. He told us that we had been very lucky to see this dolphin-whale encounter which, from his experiences with cetaceans, is probably quite rare.

Cornelia Parker

Cornelia Parker
Cold Dark Matter: An Exploded View (1991),

Silver Bank 2009

I'm back again on the Silver Bank in the Dominican Republic with the humpback whales and Tom Conlin of Aquatic Adventures, aboard the Nekton Rorqual. Artist Gregory Colbert and his crew were on board for the last ten days filming free divers with the whales. They created some beautiful images, the divers and whales sometimes appeared to be falling together through outer space.

Spin Crisis

Spin is a fundamental intrinsic property of elementary particles. QCD, Quantum Chromodynamics, should allow us to calculate the spin of a nucleon, a proton or neutron, from its component quarks and gluons. Currently there is no satisfactory explanation of the nucleon spin in terms of QCD. See Spin Structure of the Nucleon - Status and Recent Results.

Water Bridge

Water doesn't mind the gap: Gravity-defying liquid bridge makes a splash.
in Nature (2007).

It could be the world's longest liquid bridge: researchers have coaxed water into leaping a 25-millimetre gap between two regular glass beakers in a gravity-defying stunt. The engineering feat could involve a hitherto unknown microstructure of water, the researchers say.

Is Dark Matter Neutrinos?

Do non-relativistic neutrinos constitute the dark matter?
The observed dark matter distribution of a supercluster of galaxies is modelled by non-relativistic neutrinos. There is other evidence against this, however, some of which is mentioned in the paper.

Saturn Orbit Anomaly

On the recently determined anomalous perihelion precession of Saturn

The astronomer E.V. Pitjeva, by analyzing with the EPM2008 ephemerides a large number of planetary observations including also two years (2004-2006) of normal points from the Cassini spacecraft, phenomenologically estimated a statistically significant non-zero correction to the usual Newtonian/Einsteinian secular precession of the longitude of the perihelion of Saturn, i.e. \Delta\dot\varpi_Sat = -0.006 +/- 0.002 arcsec/cy; the formal, statistical error is 0.0007 arcsec/cy. It can be explained neither by any of the standard classical and general relativistic dynamical effects mismodelled/unmodelled in the force models of the EPM2008 ephemerides nor by several exotic modifications of gravity recently put forth to accommodate certain cosmological/astrophysical observations without resorting to dark energy/dark matter. Both independent analyses by other teams of astronomers and further processing of larger data sets from Cassini will be helpful in clarifying the nature and the true existence of the anomalous precession of the perihelion of Saturn.

Volcanic Eruption in HD

Guatemala's Mt. Santiaguito

More than one Time Dimension

Multiple Time Dimensions

The possibility of physics in multiple time dimensions is investigated. Drawing on recent work by Walter Craig and myself, I show that, contrary to conventional wisdom, there is a well-posed initial value problem--deterministic, stable evolution--for theories in multiple time dimensions. Though similar in many ways to ordinary, single-time theories, multi-time theories have some rather intriguing properties which suggest new directions for the understanding of fundamental physics.

Cosmic Microwave Background (CMB) Asymmetry

Title: Power Asymmetry in Cosmic Microwave Background Fluctuations from Full Sky to Sub-degree Scales: Is the Universe Isotropic?

Our results indicate that the reported common asymmetric axis extending over a large range in scales is highly unlikely to be a statistical fluke. Foregrounds and systematic effects do not seem to be probable explanations. The CMB does seem to have an uneven power distribution on the sky over a large range of angular scales. An important task for further research is to find a physical explanation for this asymmetry which can predict possible effects on CMB polarization to be tested in future experiments.

Graphene Sheets

Graphene Recipe Yields Carbon Cornucopia in Science.

The hottest material in physics these days is graphene, sheets of carbon just a single atom thick. Graphene is flexible yet harder than diamond. It conducts electricity faster at room temperature than anything else. And it's nearly transparent, a handy property for devices such as solar cells and displays that need to let light through. The only trouble is that people have been able to make only small flakes of the stuff--until now.

"Axis of Evil"

Does the Universe Have a Handedness?

In this article I extend an earlier study of spiral galaxies in the Sloan Digital Sky Survey (SDSS) to investigate whether the universe has an overall handedness. A preference for spiral galaxies in one sector of the sky to be left-handed or right-handed spirals would indicate a parity-violating asymmetry in the overall universe and a preferred axis. The previous study used 2616 spiral galaxies with redshifts <0.04 and identified handedness. The new study uses 15872 with redshifts <0.085 and obtains very similar results to the first with a signal exceeding 5 sigma, corresponding to a probability of 2.5x10-7 for occurring by chance. The axis of the dipole asymmetry lies at approx. (l, b) =(32d,69d), roughly along that of our Galaxy and close to the so-called "Axis of Evil".

Strategic Pizza

How to eat 4/9 of a pizza

Given two players alternately picking pieces of a pizza sliced by radial cuts, in such a way that after the first piece is taken every subsequent chosen piece is adjacent to some previously taken piece, we provide a strategy for the starting player to get 4/9 of the pizza. This is best possible and settles a conjecture of Peter Winkler.

Red Rectangle Nebula

Red Rectangle Nebula

Human DNA weirdness

In PNAS: The human genome in the LINE of fire.

One of the most surprising revelations of the sequencing of the human genome was that nearly half of our DNA is derived from transposable element (TE) insertions, and this is likely to be an underestimate, because many TE-derived sequences have diverged beyond recognition (1). Remarkably, the vast majority of human TE sequences result from the activity of a single class of TEs known as LINE retrotransposons. Represented by the currently active LINE-1 or L1 elements, LINEs are autonomous TEs that propagate in the genome by making RNA copies of themselves that are subsequently reverse transcribed and integrated into the genome (2–4). As a result of their ongoing activity during the past 150 million years, L1 elements account for approximately one-third of the human genome ...

Eukaryotes are a kind of Archea?

Are there three great domains of life - the Archea, Eubacteria and Eukaryotes? Or are the Eukaryotes most closely related to the Eocytes, a particular group with the Archea. This paper in PNAS supports the latter: The archaebacterial origin of eukaryotes.

Missing Baryons

Evidence for the Missing Baryons in the Angular Correlation of the Diffuse X-ray Background

The amount of detected baryons in the local Universe is at least a factor of two smaller than measured at high redshift. It is believed that a significant fraction of the baryons in the current Universe is "hiding" in a hot filamentary structure filling the intergalactic space, the Warm-Hot Intergalactic Medium ($WHIM$). We found evidence of the missing baryons in the $WHIM$ by detecting their signature on the angular correlation of diffuse X-ray emission with the XMM-Newton satellite

The Center of the Milky Way

The warped young stellar disc in the Galactic Centre

Within the central parsec of the Galaxy, several tens of young stars orbiting a central supermassive black hole are observed. A subset of these stars forms a coherently rotating disc. Other observations reveal a massive molecular torus which lies at a radius ~1.5pc from the centre. In this paper we consider the gravitational influence of the molecular torus upon the stars of the stellar disc. We derive an analytical formula for the rate of precession of individual stellar orbits and we show that it is highly sensitive upon the orbital semi-major axis and inclination with respect to the plane of the torus as well as on the mass of the torus. Assuming that both the stellar disc and the molecular torus are stable on the time-scale >6Myr, we constrain the mass of the torus and its inclination with respect to the young stellar disc. We further suggest that all young stars observed in the Galactic Centre may have a common origin in a single coherently rotating structure with an opening angle <5deg, which was partially destroyed (warped) during its lifetime by the gravitational influence of the molecular torus.

Blood Simple

I just watched Blood Simple a clever, macabre, suspenseful DVD by the Coen Brothers.

Werner Herzog

I'm currently watching Even Dwarfs Started Small a rather eccentric film directed by Werner Herzog. I've also seen two other films by him recently: Grizzly Man and My Best Fiend both documentaries, both fascinating. Aguirre, the Wrath of God is another interesting and unusual film by the same director starting Klaus Kinski, who was also the subject of My Best Fiend.
poster for Aguirre

Eye Slideshow

Darwin 200: An eye for the eye: A celebration of one of evolution's crowning glories in Nature.
Darwin's Eye

The Agulhas leakage

Agulhas leakage dynamics affects decadal variability in Atlantic overturning circulation in Nature.

The Agulhas leakage around South Africa is the main source of the warm and salty waters carried towards the subpolar North Atlantic as the upper limb of the MOC. The Agulhas leakage region is characterized by vigorous variability on intraseasonal to interannual timescales9 shedding the largest mesoscale eddies in the world ocean10, which are the dominating vehicles transporting and releasing the Indian Ocean waters into the Atlantic11. Observational palaeoclimate studies have suggested a broken inter-ocean exchange on centurial to millennial timescales12, and ocean climate model studies13, 14 have elucidated the potential of the inter-ocean exchange of heat and salt to alter the long-term MOC response. However, large uncertainties in those studies remain, owing to unresolved mesoscale processes15 that govern the dynamics and strength of the Agulhas leakage16; the present study focuses on those effects on decadal timescales.

The MOC is the meridional overturning circulation see Thermohaline circulation in Wikipedia.

Unifying Nanophotonics and Nanomechanics

Photonics: Nanomechanics gets the shakes in Nature.

Photonic circuits can allow light to be tightly confined on a chip. A clever experiment reveals how this process can be exploited to create optical forces that drive a nanoscale mechanical oscillator.

Amazing New "Nanoscope"

Microscopy: A terahertz nanoscope in Nature.
Using a very small light source and scanning it very close to the sample they are able to beat the diffraction limit - by a lot.

Hacking Victoria's Secret

Victoria Secret competition gets hacked - MIT votes for Zion Bible College:)

It was too good to be true.

With more than 5 million votes registered, Drexel University had overwhelmed the Victoria's Secret online poll to become the first school to be added to the Pink Collegiate Collection.

The nearest competition - Texas Tech and George Mason University -trailed behind Drexel by at least two million votes.

Except a majority of the votes from Drexel, and many of the other top 25 schools in the poll, were generated by computer programs.

Benford's Law

Benford's Law in Wikipedia. The digit '1' should be the most common first digit in many datasets!

Cosmic Ray Hot Spots?

Cosmic-ray hot spots puzzle researchers in Nature:

In contrast, the Milagro team, led by Jordan Goodman at the University of Maryland, College Park, found cosmic-ray protons bunched up in two 'hot spots': one between the Orion and Taurus constellations, the other near Gemini. They think that the excess cosmic rays may be coming from exotic sources such as the rapidly rotating neutron stars known as pulsars, rather than dark-matter annihilations.

Milagro website - cool.

How Termites Get Their Nitrogen

Termites eat wood, and they require nitrogen, but wood contains very little. It turns out that a protist that lives inside the termite's gut contains a bacteria which in turn fixes atmospheric nitrogen!
How Termites Live on a Diet of Wood in the New York Times and Genome of an Endosymbiont Coupling N2 Fixation to Cellulolysis Within Protist Cells in Termite Gut in Science:

Termites harbor diverse symbiotic gut microorganisms, the majority of which are as yet uncultivable and their interrelationships unclear. Here, we present the complete genome sequence of the uncultured Bacteroidales endosymbiont of the cellulolytic protist Pseudotrichonympha grassii, which accounts for 70% of the bacterial cells in the gut of the termite Coptotermes formosanus. Functional annotation of the chromosome (1,114,206 base pairs) unveiled its ability to fix dinitrogen and recycle putative host nitrogen wastes for biosynthesis of diverse amino acids and cofactors, and import glucose and xylose as energy and carbon sources. Thus, nitrogen fixation and cellulolysis are coupled within the protist's cells. This highly evolved symbiotic system probably underlies the ability of the worldwide pest termites Coptotermes to use wood as their sole food.

In the same issue of Science there's an article about nitrogen fixation in the ocean:
Globally Distributed Uncultivated Oceanic N2-Fixing Cyanobacteria Lack Oxygenic Photosystem II

Oceanic cyanobacteria are the oxygen-producing, carbon- and nitrogen-fixing engines of our planet. Because oxygen is toxic for nitrogenase, nitrogen fixation is a bit problematic to fit into this metabolic mix. Multicellular cyanobacteria like Trichodesmium have evolved a range of temporal and compartmental strategies to protect their nitrogenase enzymes from being poisoned. A newly discovered and abundant group of unicellular cyanobacteria has dispensed with carbon fixation and oxygen production altogether and so it can run nitrogenase without hindrance. Zehr et al. (p. 1110) have extracted this group by cell sorting and, by genome analysis, show that indeed it lacks the genes both for photosystem II and for carbon fixation via the reductive pentose phosphate cycle. This finding makes it necessary to reevaluate current models of nitrogen and carbon cycling on Earth.

Proton Mass from Theory

The Standard Model of particle physics is supposed to describe the properties of the quarks and gluons which make up the proton and other particles. Yet until just now isn't hasn't even been possible to calculate the mass of the proton based on the Standard Model.
See
The Weight of the World Is Quantum Chromodynamics in Science.
Nuclear masses calculated from scratch in Nature.
Particle physics: Mass by numbers by Frank Wilczek in Nature.

A highly precise calculation of the masses of strongly interacting particles, based on fundamental theory, is testament to the age-old verity that physical reality embodies simple mathematical laws.

Massive Compact Galaxies

Compact galaxies in early Universe pack a big punch

Using the Near Infrared Camera and Multi-Object Spectrometer onboard of the Hubble NASA/ESA Hubble Space Telescope, astronomers have made observations of young, surprisingly compact galaxies, each only 5000 light-years across, but weighing 200 thousand million times the mass of the Sun.

Extremely Compact Massive Galaxies at 1.7 < z < 3

One of the most exciting discoveries in extragalactic astronomy in the last few years is that massive (M ≥ 1011M⊙) galaxies at z > 1 were extremely compact ( [1]; [2]). Since these objects are not found in the local Universe ( [3]) it is clear that significant growth in the sizes of these galaxies has occurred during cosmic history.

Literature

This is what I've been reading lately:
The Girl with the Dragon Tattoo a novel by Stieg Larsson
The Aubrey-Maturin series by Patrick O'Brian
also two books by Dean King:
A Sea of Words: Lexicon and Companion for Patrick O'Brian's Seafaring Tales;
Harbors and High Seas: Map Book and Geographical Guide to the Aubrey/Maturin Novels of Patrick O'Brian
are interesting and a big help in following the O'Brian books.

I'm currently reading Krakatoa: The Day the World Exploded by Simon Winchester

Why is there Oxygen in Our Atmosphere?

The Story of O2 in Science.
Atmospheric oxygen is produced by photosynthesis, but the production of gaseous oxygen tends to be balanced by its removal by respiration. Apparently it's actually the burial of organic material which allows oxygen to accumulate in the atmosphere.

Visual Cells

There are two principal types of visual cells in animals: ciliary-type, typically found in vertebrates and other deuterostomes; and rhabdomeric-type, found in insects, molluscs, and other protostomes. Recently there's evidence that prebilaterians, the common ancestors of deuterostomes and protostomes, may have had both types of cells and that indeed both types of cells can still be found within both groups.
See Jellyfish vision starts with cAMP signaling mediated by opsin-Gs cascade in PNAS and Evolutionary biology: Light on ancient photoreceptors in Science.

Enigma Illusion

Enigma Illusion I had to stare at the image for at least 30 seconds before it started rotating.
Microsaccades drive illusory motion in the Enigma illusion in PNAS.

Nice collection of Science Images

ScienceShots at Science Magazine.
Here are a couple of favorites:
Arp 147: Hubble
Hubble

Algae that Fix Nitrogen in Daylight

Marine Algae Try Alternative Lifestyle in Science.

By transforming sunlight into food for themselves, oceanic blue-green algae multiply and provide nourishing meals for most other marine creatures. But a newly discovered group of these microorganisms forgoes this photosynthesis and, in doing so, becomes a nitrogen-rich natural fertilizer for the oceans, according to research published today in Science (p. 1110). These findings, the authors say, have important implications for nitrogen and carbon cycling in the oceans.

Transparent, Thin Loudspeakers from Carbon Nanotubes

Big Noise From Little Tubes in Science.

Last year brought news of Lilliputian radios made from whiskerlike carbon nanotubes. Now, researchers in China have added ultrathin loudspeakers to go with them. The devices, made from transparent and flexible carbon nanotube films, don't require any of the bulky magnets and sound cones of conventional speakers. So they could lead to a new generation of nearly invisible, flat speakers that can be integrated into everything from ceilings and walls to clothing and curtains.

The Evolution of Childhood

The Birth of Childhood in Science.

Unlike other apes, humans depend on their parents for a long period after weaning. But when--and why--did our long childhood evolve?

Pretty Tilings

Beautiful tilings

An Unexpected New Particle?

Has new physics been found at the ageing Tevatron?

Last week, physicists announced that the Tevatron particle accelerator at Fermilab in Batavia, Illinois, has produced particles that they are unable to explain. Could it be a sign of new physics?

Nature News

Unexplained 'ghost particles' are mysteriously appearing inside a US-based high-energy physics experiment.

Galaxies appear simpler than expected

preprint

Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment, and feedback from supernova explosions and supermassive black holes. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter. The properties of an individual galaxy should be controlled by six independent parameters including mass, angular-momentum, baryon-fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a sample of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free of optical selection effects, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our dataset. Such a degree of organisation appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter paradigm in cosmology.

The possibility of life on other planets

There could be millions of planets orbiting other stars. Thomas Carlyle commented "A sad spectacle! If they be inhabited, what a scope for pain and folly; and if they be not inhabited, what a waste of space!"

Imaging Single Atoms on a Graphene Sheet

Single atoms spied on graphene sliver: Electron microscope spots hydrogen atoms resting on invisible carbon sheet.

Graphene is a single sheet of carbon atoms arranged in a hexagonal pattern. It can be used as a transparent "slide" so that a transmission electon microscope can image individual atoms, even hydrogen, the smallest.

A revolution occurred when it was discovered that the single atom sheets of graphene could be peeled off common graphite using adhesive tape!

Graphene at Wikipedia.

More Weird Quantum Behaviour

Paradoxical Reflection in Quantum Mechanics

This article concerns a phenomenon of elementary quantum mechanics that is quite counter-intuitive, very non-classical, and apparently not widely known: a quantum particle can get reflected at a potential step downwards. In contrast, classical particles get reflected only at upward steps. As a consequence, a quantum particle can be trapped for a long time (though not forever) in a region surrounded by downward potential steps, that is, on a plateau. Said succinctly, a quantum particle tends not to fall off a table. The conditions for this effect are that the wave length is much greater than the width of the potential step and the kinetic energy of the particle is much smaller than the depth of the potential step. We point out how the topic is accessible with elementary methods, but also with mathematical rigor and numerically.

An Exceptionally Simple Theory of Everything

This preprint by Garrett Lisi has been getting a lot of press in the popular media, in part because the author is a "surfer dude". Here's an article at the New Yorker: Surfing the Universe An academic dropout and the search for a Theory of Everything. Here's the discussion (some of it heated) at the backreaction physics blog and also at Woit's Not Even Wrong blog. Lisi himself comes off as an unassuming, pleasant, amiable fellow, much in contrast to many of the other commenters.
How can a "Theory of Everything" be "Exceptionally Simple"? Sorry, it's a pun, 'Exceptional' and 'Simple' are technical terms from mathematical Group Theory, the new theory relies on very advanced mathematics and theoretical physics.

Here's a pretty graphical illustration of the theory, but don't expect to watch it and actually understand anything.

Another Kieslowski Film

I'm watching No End, a little Polish film from the eighties.
Kieslowski is a genius.


Film poster

Surprising Ancient Zircons

Constraints on Hadean zircon protoliths from oxygen isotopes, Ti-thermometry, and rare earth elements one of the coauthors of this paper is named "Dustin Trail"!
Oxygen-isotope evidence from ancient zircons for liquid water at the Earth's surface 4,300 Myr ago
4.4 billion years of crustal maturation: oxygen isotope ratios of magmatic zircon

Here's a nice summary as of July 2007:GEOLOGY: Early Earth Mirrored in Zircon

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.

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

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.

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.

Anne Adams

Anne and Robert Adams

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

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.

Einstein's Relativity Song

The date it was posted on Youtube - April 1.

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

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.

Build your own Rebreather for $100 ...

... using a hot water bottle: A HOT WATER BOTTLE PENDULUM

Warning Warning Warning

REBREATHERS CAN AND DO KILL
I AM NOT RESPONSIBLE FOR YOU
YOU MAKE YOUR OWN DECISIONS
AND REAP THE CONSEQUENCES



You can die from too much oxygen by using pure oxygen below 20 feet of seawater. You can die from too little oxygen. You can drown. Screw up and you are likely to die. When you enter the water, you are on your own, even if a buddy is nearby. You alone must make the decision that you are capable of using a rebreather, you are up to the dive, and that your equipment is up to the dive. Even extensive open circuit experience will not prepare you for the details inherent with staying alive underwater on a rebreather. If you have any concerns about your abilities, take a course or do not dive. If you are foolish enough to dive rebreathers, be aware that it is a case of Evolution in Action. It is an effective sorting out process that has created many unhappy widows, mothers, and children. I recommend against it. This project is described for your amusement only. It is not the intent of the author that you build one of these and go out and kill yourself. As I have shown it, if you take the mouthpiece out of your mouth, water will flow in filling the scrubber, and your next breath is a caustic cocktail. If you don't know what you are doing, don't try this one at home. If you know what you are doing, I am sure you have a rig that makes this one look childish.

Information Storage in the Brain

Compartmentalized dendritic plasticity and input feature storage in neurons in Nature.

Although information storage in the central nervous system is thought to be primarily mediated by various forms of synaptic plasticity, other mechanisms, such as modifications in membrane excitability, are available. Local dendritic spikes are nonlinear voltage events that are initiated within dendritic branches by spatially clustered and temporally synchronous synaptic input. That local spikes selectively respond only to appropriately correlated input allows them to function as input feature detectors and potentially as powerful information storage mechanisms. However, it is currently unknown whether any effective form of local dendritic spike plasticity exists. Here we show that the coupling between local dendritic spikes and the soma of rat hippocampal CA1 pyramidal neurons can be modified in a branch-specific manner through an N-methyl-d-aspartate receptor (NMDAR)-dependent regulation of dendritic Kv4.2 potassium channels. These data suggest that compartmentalized changes in branch excitability could store multiple complex features of synaptic input, such as their spatio-temporal correlation. We propose that this 'branch strength potentiation' represents a previously unknown form of information storage that is distinct from that produced by changes in synaptic efficacy both at the mechanistic level and in the type of information stored.

Traffic Jams Just Happen

Traffic Jams Happen, Get Used to It in Science Magazine.

Roundabout.
Too many cars equals a traffic jam, even without an external cause.
Credit: Mathematical Society of Traffic Flow

Precision Clocks

A Milestone in Time Keeping in Science Magazine.

Researchers have made atomic clocks so precise that effects of general relativity are on the verge of complicating the concept of keeping time.

So much for "junk DNA"

Only 1-2% of the DNA in humans and other higher organisms appears to code for proteins. But the remaining so-called "junk DNA" may be transribed into RNA with numerous functions.
The Eukaryotic Genome as an RNA Machine in Science Magazine.

The past few years have revealed that the genomes of all studied eukaryotes are almost entirely transcribed, generating an enormous number of non–protein-coding RNAs (ncRNAs). In parallel, it is increasingly evident that many of these RNAs have regulatory functions. Here, we highlight recent advances that illustrate the diversity of ncRNA control of genome dynamics, cell biology, and developmental programming.

Cliche Mashups

Growing Pangs: growing pains / birth pangs --- attributed to Condi Rice

No Shit Jose: No Shit Sherlock / No Way Jose

Don't Bite the F---ing Horse: Don't Bite the Hand That Feeds You / Don't Look a Gift Horse in the Mouth

Green Behind the Ears: green / wet behind the ears --- Barack Obama in 2008 Presidential Debate

"They create a desolation and call it peace"

From Tacitus, Agricola, a rebel's comment about Rome.

Science as Art Competition

Image: Fanny Beron, École Polytechnique de Montréal, Montréal, Canada)
Science as Art competition held at the 2007 Materials Research Society (MRS) Fall Meeting

Speed Camera Irony

Cities that have installed speed cameras are discovering motorists are driving slower, which is decreasing revenues from fines. So they're turning the cameras off.

Schneier on Security

You First

Galaxy Rotation

Disk galaxy rotation curves and dark matter distribution

After explaining the motivation for this article, we briefly recapitulate the methods used to determine somewhat coarsely the rotation curves of our Milky Way Galaxy and other spiral galaxies, especially in their outer parts, and the results of applying these methods. Recent observations and models of the very inner central parts of galaxian rotation curves are only briefly described. We then present the essential Newtonian theory of (disk) galaxy rotation curves. The next two sections present two numerical simulation schemes and brief results. Application of modified Newtonian dynamics to the outer parts of disk galaxies is then described. Finally, attempts to apply Einsteinian general relativity to the dynamics are summarized. The article ends with a summary and prospects for further work in this area