A Brief History of Planet Earth

The Earth – For Physicists is an article by John Baez with a somewhat unfortunate title. You don't actually need a background in physics to follow this synopsis of the origin and development of our planet.

Definitions in Kindle

Though the Kindle user interface is admittedly rather rudimentary, there's one seemingly minor feature that works great in practice. While reading a document, when you move the cursor onto a word it gives you a one line definition at the bottom of the screen. Hit return and it switches to a screen with the complete definition. I use this feature quite frequently. Even when I'm more or less familiar with a word, it's sometimes nice to check the exact definition. I don't check definitions nearly enough when I read normally, due to laziness, but the Kindle makes it painless enough that I've been actually doing it.

Kindle Shines in the Sun

I recently purchased a Kindle DX from Amazon, mainly hoping to use it while travelling. I've more or less ignored it since the first couple of days after it arrived. But today is a gorgeous sunny day for a change here in Boston, so I decided to try to read something out on my deck, which is blazingly bright today. I brought out the Kindle and was pleasantly surprised by how easy it was to read while wearing a pair of extremely dark polarized sunglasses. I found reading on the Kindle easier on my eyes than a paperback book, perhaps in part because the print is somewhat larger on the Kindle. As a joke, I brought out my laptop. I could barely see anything on the laptop screen in the sunlight without my sunglasses and absolutely nothing with the sunglasses on.
On a nice sunny day I often would like to read outdoors, but usually find the eye strain too much. The Kindle seems to help in this situation.

On the other hand the E Ink display used by the Kindle has its quirks too: there's a dramatic flash when the page is changed and there's long decay time when erasing the cursor, etc. However, I don't really even notice the page change flash anymore, though I certainly did when I first got it.

This Snake is a Fake Out Artist

The Tentacled Snake, an aquatic reptile of southeast Asia, does a nice job of faking out its fish prey: Tentacled snakes turn C-starts to their advantage and predict future prey behavior.

Many People Reject Unfair Offers Even When They Screw Only Themselves

The private rejection of unfair offers and emotional commitment

In a series of experiments, we demonstrate that certain players of an economic game reject unfair offers even when this behavior increases rather than decreases inequity. A substantial proportion (30–40%, compared with 60–70% in the standard ultimatum game) of those who responded rejected unfair offers even when rejection reduced only their own earnings to 0, while not affecting the earnings of the person who proposed the unfair split (in an impunity game). Furthermore, even when the responders were not able to communicate their anger to the proposers by rejecting unfair offers in a private impunity game, a similar rate of rejection was observed. The rejection of unfair offers that increases inequity cannot be explained by the social preference for inequity aversion or reciprocity; however, it does provide support for the model of emotion as a commitment device. In this view, emotions such as anger or moral disgust lead people to disregard the immediate consequences of their behavior, committing them to behave consistently to preserve integrity and maintain a reputation over time as someone who is reliably committed to this behavior.

Giant Kangaroo was probably wiped out by Humans

The largest-ever kangaroo, Procoptodon goliah disappeared about the time that humans arrived in Australia. It appears that was not a coincidence: Extinction implications of a chenopod browse diet for a giant Pleistocene kangaroo.

A Tight Biological Loop

Prochlorococcus, a tiny photosynthesing marine bacteria, is one of the smallest and most abundant forms of life. It needs nitrogen which is often a limiting factor in its growth. Apparently a major source of its nitrogen is nitrate, which is produced by organsims which mainly feed on Prochlorococcus itself: Prochlorococcus: Approved for export!

The Economics of Piracy

Aaaargh-onomics a blog post in the New York Times by Edward L. Glaeser of Harvard, reviews Peter Leeson’s book “The Invisible Hook: The Hidden Economics of Pirates.”

Mr. Leeson’s book represents a serious attempt to use the tools of economics to make sense of the institutions of piracy. The book is another example of economic imperialism, the use of economics to make sense of real world phenomena that are outside the standard realm of economic science. It addresses an important force that did, and does, impact world trade. But as the skull and crossbones on its spine suggests, the book is also just fun.

Benford, Zipf and Pareto

In this blog post Benford’s law, Zipf’s law, and the Pareto distribution Fields medalist Terence Tao discusses three remarkable real-world statistical patterns: Benford’s law, Zipf’s law, and the Pareto distribution.

Isn't it Ironic?

How to Think, Say, or Do Precisely the Worst Thing for Any Occasion

In slapstick comedy, the worst thing that could happen usually does: The person with a sore toe manages to stub it, sometimes twice. Such errors also arise in daily life, and research traces the tendency to do precisely the worst thing to ironic processes of mental control. These monitoring processes keep us watchful for errors of thought, speech, and action and enable us to avoid the worst thing in most situations, but they also increase the likelihood of such errors when we attempt to exert control under mental load (stress, time pressure, or distraction). Ironic errors in attention and memory occur with identifiable brain activity and prompt recurrent unwanted thoughts; attraction to forbidden desires; expression of objectionable social prejudices; production of movement errors; and rebounds of negative experiences such as anxiety, pain, and depression. Such ironies can be overcome when effective control strategies are deployed and mental load is minimized.

Hurricane Prediction

There appears to be a connection between Central Pacific Warming events and the severity and pattern of hurricanes in the North Atlantic. Central Pacific Warming events occur around the international dateline and are apparently distinct from Eastern Pacific Warming events - El Nino: Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones and Predicting El Niño's Impacts.

The Russians are going to Phobos

Phobos, one of the moons of Mars, is a strange object. The Russians are launching a sample return mission this year: Russia's Dark Horse Plan to Get to Mars.

Valentini's Critique of Quantum Theory

Is Quantum Mechanics Tried, True, Wildly Successful, and Wrong?

A skeptical physicist charges that his field has been wandering in a philosophical wilderness for 80 years. The good news: He thinks he knows the way out.

Many of Antony Valentini's other papers can also be found at arXiv by clicking on the author's name in this link: Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference

We reconsider the crucial 1927 Solvay conference in the context of current research in the foundations of quantum theory. Contrary to folklore, the interpretation question was not settled at this conference and no consensus was reached; instead, a range of sharply conflicting views were presented and extensively discussed. Today, there is no longer an established or dominant interpretation of quantum theory, so it is important to re-evaluate the historical sources and keep the interpretation debate open. In this spirit, we provide a complete English translation of the original proceedings (lectures and discussions), and give background essays on the three main interpretations presented: de Broglie's pilot-wave theory, Born and Heisenberg's quantum mechanics, and Schroedinger's wave mechanics. We provide an extensive analysis of the lectures and discussions that took place, in the light of current debates about the meaning of quantum theory. The proceedings contain much unexpected material, including extensive discussions of de Broglie's pilot-wave theory (which de Broglie presented for a many-body system), and a "quantum mechanics" apparently lacking in wave function collapse or fundamental time evolution. We hope that the book will contribute to the ongoing revival of research in quantum foundations, as well as stimulate a reconsideration of the historical development of quantum physics. A more detailed description of the book may be found in the Preface. (Copyright by Cambridge University Press (ISBN: 9780521814218), expected publication date 2007.)

Cosmic Reionization

Computer Simulations of Cosmic Reionization

The cosmic reionization of hydrogen was the last major phase transition in the evolution of the universe, which drastically changed the ionization and thermal conditions in the cosmic gas. To the best of our knowledge today, this process was driven by the ultra-violet radiation from young, star-forming galaxies and from first quasars. We review the current observational constraints on cosmic reionization, as well as the dominant physical effects that control the ionization of intergalactic gas. We then focus on numerical modeling of this process with computer simulations. Over the past decade, significant progress has been made in solving the radiative transfer of ionizing photons from many sources through the highly inhomogeneous distribution of cosmic gas in the expanding universe. With modern simulations, we have finally converged on a general picture for the reionization process, but many unsolved problems still remain in this young and exciting field of numerical cosmology.

Graphene

Graphene: Status and Prospects

Graphene is a wonder material with many superlatives to its name. It is the thinnest material in the universe and the strongest ever measured. Its charge carriers exhibit giant intrinsic mobility, have the smallest effective mass (it is zero) and can travel micrometer-long distances without scattering at room temperature. Graphene can sustain current densities 6 orders higher than copper, shows record thermal conductivity and stiffness, is impermeable to gases and reconciles such conflicting qualities as brittleness and ductility. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a bench-top experiment. What are other surprises that graphene keeps in store for us? This review analyses recent trends in graphene research and applications, and attempts to identify future directions in which the field is likely to develop.

The Evolution of Sex

On the Origin of Sexual Reproduction

Sexual reproduction is costly, so what are the benefits? One of the hypotheses has a catchy name: the Red Queen theory - from the Lewis Carroll character who tells Alice she must keep running faster just to stay in the same place. In biology it's the theory that organisms have to keep changing to keep ahead of their parasites. The recombination of characteristics in sexual reproduction may help.
The widespread system of sexual reproduction found in humans and many other eukaryotes alternates haploid and diploid stages. In humans the gametes (egg and sperm) are hapolid, they only have one copy of each chromosome, while embryos and adult forms are diploid, they have two copies of each chromosome. There's an elaborate mechanism, meiosis, which converts the diploid form into the haploid form. There's another mechanism, ferilizaton, which goes from two haploid forms (the egg and sperm) to the diploid form.

The Evolution of Meiosis From Mitosis

... if there is one event in the whole evolutionary sequence at which my own mind lets my awe still overcome my instinct to analyse, and where I might concede that there may be a difficulty in seeing a Darwinian gradualism hold sway throughout almost all, it is this event—the initiation of meiosis. W. J. HAMILTON (999, p. 419)

THE origins of meiosis in early eukaryotic history have never been satisfactorily explained. Since the reduction-division process in meiosis is essential for sexual life cycles, discussion of the origins of meiosis has been closely tied to debates about the evolutionary value of sex itself and the selective pressures for its maintenance. Yet the cytological events involved in the origins of meiosis are as puzzling as the question of selective pressures. While meiosis almost certainly evolved from mitosis, it has not one but four novel steps: the pairing of homologous chromosomes, the occurrence of extensive recombination between non-sister chromatids during pairing, the suppression of sister-chromatid separation during the first meiotic division, and the absence of chromosome replication during the second meiotic division. This complexity presents a challenge to any Darwinian explanation of meiotic origins. While the simultaneous creation of these new features in one step seems impossible, their step-by-step acquisition via selection of separate mutations seems highly problematic, given that the entire sequence is required for reliable production of haploid chromosome sets. Both Maynard Smith (1978) and Hamilton (1999) regarded the origins of meiosis as one of the most difficult evolutionary problems.

This article discusses something which always bothered me. In meiosis, the chromosomes are replicated first, resulting in four copies of each homolog chromosome. But each gamete requires only one copy. Why not seperate into two gametes directly, without the initial replication - it seems simpler. Apparently, since meiosis evolved from mitosis, and the initial replication is very similiar to what happens in mitosis, it is a relatively simple evolutionary change.

Thus, and perhaps counterintuitively, the evolution of two-step meiosis requires fewer new events than the seemingly simpler one-step process

This article proposes that the main benefit of meiosis is prevention of damage during recombination. Recombination itself is helpful for repairing damaged chromosomes.

Wavefunction Uncollapse

Uncollapsing the wavefunction by undoing quantum measurements

We review and expand on recent advances in theory and experiments concerning the problem of wavefunction uncollapse: Given an unknown state that has been disturbed by a generalized measurement, restore the state to its initial configuration. We describe how this is probabilistically possible with a subsequent measurement that involves erasing the information extracted about the state in the first measurement.

Fool's Gold

Fool's Gold: How the Bold Dream of a Small Tribe at J.P. Morgan Was Corrupted by Wall Street Greed and Unleashed a Catastrophe. Author Gillian Tett follows the staff of J.P. Morgan as they developed new financial instruments (various kinds of derivatives) to better manage risk - and which ended up being used in very risky ways that significantly contributed to the current financial meltdown.

Carlos Castenada

Carlos Castenada was a UCLA anthropology student who wrote a popular series of books in the 1970's about his research into the practices of native Mexican "sorcerers" which included the consumption of psychoactive plants. As it turns out, he also had a cult, based in Los Angeles, largely of women devotees, some of whom were supposed to be witches. When Castenada died of cancer in the late nineties, five of the women disappeared without a trace - it is assumed they committed suicide. A skeleton found in Death Valley was identified as one of the "witches" in 2006. See The dark legacy of Carlos Castaneda in Salon and The Sorcerer's Apprentice: My Life with Carlos Castaneda by Amy Irving.

Isotope Separation

SWU for U and Me by Jeremy Bernstein. Urananium isotope seperation has been in the news of late because of Iran's efforts in this arena. This paper explains some of the theory behind gas centrifuges and some of the fascinating history as well. If equations aren't your cup of tea, try skipping past those sections to the ancedotes.

The Evolution of Cell membranes

Cell membranes are largely composed of phospholipids. Phospholipids in turn are built on a glycerol phosphate. The are two different glycerol phosphates in use, glycerol-1-phosphate (G1P) and glycerol-3-phosphate (G3P). The archaea use G1P and the eubacteria and the eukaryotes use G3P. The two phospholipids are synthesized in entirely different ways. The mystery is, how did two such different systems evolve, and what was the nature of the common ancestor? Compounding the mystery, eukaryote transciption and translation is similiar to the archea, while eukaryote cell membranes are similar to bacteria. See Ancestral lipid biosynthesis and early membrane evolution and archea cell membranes.

Julian Schnabel

The Nerve and the Will is a beautiful review of the work of Julian Schnabel, in the New York Review of Books.

Machiavellian Monkeys

Never Trust a Hungry Monkey
Monkeys give false alarms and then take food when the other monkeys run off.

Mechanical Entanglement

Quantum mechanics: Entanglement goes mechanical

A neat experiment shows that the mechanical vibration of two ion pairs separated by a few hundred micrometres is entangled — their motions are intrinsically and inseparably connected in a quantum way.

Entangled mechanical oscillators

Hallmarks of quantum mechanics include superposition and entanglement. In the context of large complex systems, these features should lead to situations as envisaged in the 'Schrödinger's cat'1 thought experiment (where the cat exists in a superposition of alive and dead states entangled with a radioactive nucleus). Such situations are not observed in nature. This may be simply due to our inability to sufficiently isolate the system of interest from the surrounding environment2, 3—a technical limitation. Another possibility is some as-yet-undiscovered mechanism that prevents the formation of macroscopic entangled states4. Such a limitation might depend on the number of elementary constituents in the system5 or on the types of degrees of freedom that are entangled. Tests of the latter possibility have been made with photons, atoms and condensed matter devices6, 7. One system ubiquitous to nature where entanglement has not been previously demonstrated consists of distinct mechanical oscillators. Here we demonstrate deterministic entanglement of separated mechanical oscillators, consisting of the vibrational states of two pairs of atomic ions held in different locations. We also demonstrate entanglement of the internal states of an atomic ion with a distant mechanical oscillator. These results show quantum entanglement in a degree of freedom that pervades the classical world. Such experiments may lead to the generation of entangled states of larger-scale mechanical oscillators8, 9, 10, and offer possibilities for testing non-locality with mesoscopic systems11. In addition, the control developed here is an important ingredient for scaling-up quantum information processing with trapped atomic ions

Giant Neutrinos from the Big Bang

Quantum physics: Attack of the giant neutrinos
Quantum Coherence of Relic Neutrinos

What is the entropy of the universe?

What is the entropy of the universe?

Standard calculations suggest that the entropy of our universe is dominated by black holes, whose entropy is of order their area in Planck units, although they comprise only a tiny fraction of its total energy. Statistical entropy is the logarithm of the number of microstates consistent with the observed macroscopic properties of a system, hence a measure of uncertainty about its precise state. Therefore, assuming unitarity in black hole evaporation, the standard results suggest that the largest uncertainty in the future quantum state of the universe is due to the Hawking radiation from evaporating black holes. However, the entropy of the matter precursors to astrophysical black holes is enormously less than that given by area entropy. If unitarity relates the future radiation states to the black hole precursor states, then the standard results are highly misleading, at least for an observer that can differentiate the individual states of the Hawking radiation.

The Mass Gap

In THE PROBLEM OF GAUGE THEORY Edward Witten discusses the mass gap in quantum field theory, one of the Clay Institute Millenium Prize problems.

The White Tiger

While on a scuba diving trip to Cocos Island last week, I read The White Tiger the 2008 Man Booker award winner, a coming-of-age story about a poor young man in India.

Self Control Studies in the New Yorker

Don’t! The secret of self-control

William Blake - Auguries of Innocence

William Blake - Auguries of Innocence

To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour.

...

Joy and woe are woven fine,
A clothing for the soul divine.
Under every grief and pine
Runs a joy with silken twine.

Lepton Oscillations

Do charged leptons oscillate?

The question of whether charged leptons oscillate is discussed in detail, with a special emphasis on the coherence properties of the charged lepton states created via weak interactions. This analysis allows one to clarify also an important issue of the theory of neutrino oscillations.

The Fall of the Roman Empire

I just finished reading How Rome Fell by Adrian Goldsworthy. I found the story of the last "pagan" emperor Julian the Apostate most fascinating.

The Cartwheel Galaxy

The Cartwheel Galaxy may be the result of a collision with one of the two nearby galaxies to its right.
Hubble Space Telescope - NASA

Sahara Dust and Atlantic Ocean Temperatures

The Role of Aerosols in the Evolution of Tropical North Atlantic Ocean Temperature Anomalies

Observations and models show that northern tropical Atlantic surface temperatures are sensitive to regional changes in stratospheric volcanic and tropospheric mineral aerosols. However, it is unknown whether the temporal variability of these aerosols is a key factor in the evolution of ocean temperature anomalies. We used a simple physical model, incorporating 26 years of satellite data, to estimate the temperature response of the ocean mixed layer to changes in aerosol loadings. Our results suggest that the mixed layer’s response to regional variability in aerosols accounts for 69% of the recent upward trend, and 67% of the detrended and 5-year low pass–filtered variance, in northern tropical Atlantic Ocean temperatures.

Free Will

The Sources of Human Volition

Every day we make actions that seem to depend on our "free will" rather than on any obvious external stimulus. This capacity not only differentiates humans from other animals, but also gives us the clear sense of controlling our bodies and lives. It therefore forms a key element of our personal identity. However, such voluntary actions are a puzzle for modern neuroscience. Where do they come from? A study by Desmurget et al. (1) on page 811 of this issue reveals how the brain may produce our experience of initiating voluntary action.

Edgar Allan Poe - Cosmologist

If the universe is infinite and homogeneous why is the night sky dark? There's an argument that really the entire sky should be just as bright as the sun. That's called Olbers' paradox. Edgar Allan Poe was athe first to suggest a solution to this problem - that perhaps the universe had a beginning in time.

Face Recognition

Symmetry, probability, and recognition in face space

e essential midline symmetry of human faces is shown to play a key role in facial coding and recognition. This also has deep and important connections with recent explorations of the organization of primate cortex, as well as human psychophysical experiments. Evidence is presented that the dimension of face recognition space for human faces is dramatically lower than previous estimates. One result of the present development is the construction of a probability distribution in face space that produces an interesting and realistic range of (synthetic) faces. Another is a recognition algorithm that by reasonable criteria is nearly 100% accurate.

Green Fluorescent Protein

Green glow deciphered - Mysterious jellyfish gene widely used in biology find its place in nature.

Space Clocks

Title: Orbit determination for next generation space clocks

Over the last decade of the 20th century and the first few years of the 21st, the uncertainty of atomic clocks has decreased by about two orders of magnitude, passing from the low 10^-14 to below 10^-16, in relative frequency . Space applications in fundamental physics, geodesy, time/frequency metrology, navigation etc... are among the most promising for this new generation of clocks. Onboard terrestrial or solar system satellites, their exceptional frequency stability and accuracy makes them a prime tool to test the fundamental laws of nature, and to study gravitational potentials and their evolution.
In this paper, we study in more detail the requirements on orbitography compatible with operation of next generation space clocks at the required uncertainty based on a completely relativistic model. Using the ACES (Atomic Clock Ensemble in Space) mission as an example, we show that the required accuracy goal can be reached with relatively modest constraints on the orbitography of the space clock, much less stringent than expected from "naive" estimates. Our results are generic to all space clocks and represent a significant step towards the generalised use of next generation space clocks in fundamental physics, geodesy, and time/frequency metrology

Time

Time as an Illusion

We review the idea, due to Einstein, Eddington, Hoyle and Ballard, that time is a subjective label, whose primary purpose is to order events, perhaps in a higher-dimensional universe. In this approach, all moments in time exist simultaneously, but they are ordered to create the illusion of an unfolding experience by some physical mechanism. This, in the language of relativity, may be connected to a hypersurface in a world that extends beyond spacetime. Death in such a scenario may be merely a phase change.

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.