Sunday, November 30, 2008

Eye Slideshow

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

Friday, November 28, 2008

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.

Thursday, November 27, 2008

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.

Tuesday, November 25, 2008

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.

Saturday, November 22, 2008

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.
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.

Wednesday, November 19, 2008

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.

Tuesday, November 18, 2008


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

Sunday, November 16, 2008

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.

Saturday, November 15, 2008

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

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?

Tuesday, November 11, 2008

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

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.