ADAMANT

Another Flavor Of Thunderbolt

The atmospheric chemistry of the largest planet in the solar system, and the other gas giants as well, has taken an oddly solid turn with the announcement that ,at what pass for moderate pressures in the outer reaches of Jupiter's atmosphere ( there's metallic hydrogen further down ) , ammonia undergoes a phase transition that disproportionates it into solid ammonium amide --  so  NH3 rain  may turn to sleet even when falling into warmer regions.-

Nature Materials 7, 775 - 779 (2008) 
Published online: 24 August 2008 | doi:10.1038/nmat2261

Subject Category: Computation, modelling and theory

Highly compressed ammonia forms an ionic crystal

Chris J. Pickard¹ & R. J. Needs²

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Ammonia is an important compound with many uses, such as in the manufacture of fertilizers, explosives and pharmaceuticals. As an archetypal hydrogen-bonded system, the properties of ammonia under pressure are of fundamental interest, and compressed ammonia has a significant role in planetary physics. We predict new high-pressure crystalline phases of ammonia (NH₃) through a computational search based on first-principles density-functional-theory calculations¹. Ammonia is known to form hydrogen-bonded solids^{2, 3, 4, 5, 6}, but we predict that at higher pressures it will form ammonium amide ionic solids consisting of alternate layers of NH₄⁺ and NH₂^- ions. These ionic phases are predicted to be stable over a wide range of pressures readily obtainable in laboratory experiments. The occurrence of ionic phases is rationalized in terms of the relative ease of forming ammonium and amide ions from ammonia molecules, and the volume reduction on doing so. We also predict that the ionic bonding cannot be sustained under extreme compression and that, at pressures beyond the reach of current static-loading experiments, ammonia will return to hydrogen-bonded structures consisting of neutral NH₃ molecules.

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1. Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
2. Theory of Condensed Matter Group, Cavendish Laboratory, Cambridge CB3 0HE, UK

Correspondence to: Chris J. Pickard¹ e-mail: [email protected]

Reweaving The Rainbow

If you're wondering what 's next in non-linear optics:

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Nature Physics 4, 716 - 720 (2008)
Published online: 31 August 2008 | doi:10.1038/nphys1056

Linked and knotted beams of light

William T. M. Irvine^1,2 & Dirk Bouwmeester^2,3

Maxwell's eqations allow for curious solutions characterized by the property that all electric and magnetic field lines are closed loops with any two electric (or magnetic) field lines linked. These little-known solutions, constructed by Rañada¹, are based on the Hopf fibration. Here we analyse their physical properties to investigate how they can be experimentally realized. We study their time evolution and uncover, through a decomposition into a spectrum of spherical harmonics, a remarkably simple representation. Using this representation, first, a connection is established to the Chandrasekhar–Kendall curl eigenstates², which are of broad importance in plasma physics and fluid dynamics. Second, we show how a new class of knotted beams of light can be derived, and third, we show that approximate knots of light may be generated using tightly focused circularly polarized laser beams. We predict theoretical extensions and potential applications, in fields ranging from fluid dynamics, topological optical solitons and particle trapping to cold atomic gases and plasma confinement.

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1. Center for Soft Condensed Matter Research, Department of Physics, New York University, New York 10003, USA
2. Department of Physics, University of California, Santa Barbara, California 93106, USA
3. Huygens Laboratory, Leiden University, PO Box 9504, 2300 RA Leiden, The Netherlands

Correspondence to: William T. M. Irvine^1,2 e-mail: [email protected]

The Plurality Of Worlds

Lots Of Them

Scientists often see farther by standing on the shoulders of  their tallest colleagues , but the latest extension of  astronomical insight comes from an arid but remarkably un-dusty mountaintop in Chile called La Silla ,which hosts what can only described as a telescope theme park, sporting glass giants that are outliers of the world's great observatories

In recent years, a Swiss group headed by  Michel Mayor of the University Of Geneva  has used the 3.6 meter instrument of  The European Organisation for Astronomical Research in the Southern Hemisphere  to gather light for 'HARPS.'  The  High Accuracy Radial Velocity Planet Searcher detects the small wobbles in star motion that signal orbiting planets

At a conference in Nantes ,France, the group has announced finding a triple system of super-Earths  - planets intermediate in mass between ours and Neptune-  orbiting the star HD 40307.

Looking at HARPS scans to date  , they count a total of 45  such objects with orbital periods shorter than 50 days, implying s that one sun-like star  star out of three harbors such planets.

"Does every single star harbor planets and, if yes, how many?" wonders Mayor "We may not yet know the answer but we are making huge progress towards it."

Since the discovery  of a planet around the star 51 Pegasi in 1995, more than 270 exoplanets have been found,  the majority around solar-like stars. Most are hot , Jupiter sized giants of a sort current statistics suggest can be found orbiting  1 out of 14 stars. "With the advent of much more precise instruments such as the HARPS spectrograph on ESO's 3.6-m telescope at La Silla, we can now discover smaller planets, with masses between 2 and 10 times the Earth's mass," says  Stéphane Udry,adding  that "“Detection of planets with masses of about 2 Earth-masses --maybe less-- is possible,”

To do much better, astronomers will have to look through the next generation of NASA  deep  space telescopes- the first of which, the Webb Telescope,  should be orbited  within a decade.

There is a  double  irony in where the Swiss group announced its confirmation of the once-heretical doctrine of the Plurality Of Worlds. At  Nantes in 1598 was declared the Edict granting  freedom of religion to  the French Protestant followers of John Calvin of Geneva. Two years later, putting too much faith in freedom of conscience , Giordano Bruno  foolishly voiced the belief that ours might not be the only world  riven by wars of religion, and was burnt at the stake for his trouble.This  had a chilling effect on  further speculation, despite  the rapid advance of astronomical instruments in the decades that followed.

in 1624, Gallileo died under house arrest , his persecution by The Inquisition  preceding by several decades the excommunication from his synagogue of Dutch lens grinder,  Benedictus Spinoza, purveyor of telescope objectives to Christian Huygens and  the Royal Society and author of the explicit phrase ' the plurality of worlds.'  Thirteen years after he died in poverty,the Edict Of Nantes was revoked, and St Augustine's condemnation of scientific curiousity was restored to the reverence it still enjoys in some quarters to this day.

It takes a tough man to raise a tender T. Rex

In today's Science , Lewis C. Cantley and John Asara  of Harvard announce the results of DNA workup on  bones of a  T. Rex John Horner, right,  excavated in Montana five years ago
“Our results at the genetic level basically agree with what has been seen in skeletal data,” John M. Asara of Harvard said in a telephone interview. “There is more than a 90 percent probability that the grouping of T. rex with living birds is real.” Asara said.

This will cause a major shakeup in the family tree of vertebrates , as  T. rex  genetic makeup  overlaps more with ostriches and chickens than such toothy modern reptiles as alligators. Mary H. Schweitzer of North Carolina State University discovered the  still smelly preserved soft tissues in the bones.
Evolutionary biologists compared the dinosaur protein with similar protein from several dozen species of modern birds , reptiles and  amphibians.

Claire De Lune

The giant outer planets vast magnetospheres  gather  in the solar wind  like spinnakers , concentrating protons into radiation belts that dwarf the earth's . Our Van Allen belts deliver enough radiation to keep astronauts from lingering - but the vortices of charged particles  whirling around  Jupiter and Saturn and their moons  would strike a human dead in a matter of hours .

The magnetic fields also peel off ions from the moons,  so the plumes of volcanic eruptions on Io end up  as ion beams spiraling into Jupiters magnetic poles rather as the solar wind is concentrated into the Northern Lights on Earth, witness this eerie  ultraviolet image of Io's ionic doppelganger  focused into a point by the capture of field lines linking the magnetosphere of Jupiter and its satellites.  The moon in turn gets roasted by the capture of ions from the gas giant's magnetosphere, inflicting  xenomict radiation damage on the  minerals on its cold surface- an area of astrophysics on which I recently published in Naturwissenschaften , and wrote of here.

Meanwhile on Saturn's moon Enceladus, things are warming up mysteriously- the ice geysers at its south pole have been imaged in the far infrared, and though the false color highs in this photo are still far below freezing  a the data suggest a deep lying liquid water ocean beneath a thick mantle of ice . Since both methane and ammonia are being ejected as well,  the possibility of a life sustaining environment cannot be excluded at this stage

Ein Kleine Rapmusik

The opponents of Expelled have mustered an OK Chorale , and something utterly missing in Ben Stein's  corner of the latest Culture Wars battlefield-a sense of humor:

The Oldest Sight Yet Seen

                                                                 

   NASA's Swift gamma ray satellite  was struck last week by a blast of gamma rays from an event half as old as the observable universe.  so violent was the event that had it occurred in  the center of our galaxy, the milky Way would have lit up brighter than the noonday sun. Alerted by Swift, the Very Large Telescope in Chile swung to focus on the burst coordinates and captured a spectrum - the peak luminosity was such that the event was probably visible to the naked eye , making it the oldest sight  so far seen by man  .

Although visible light  photons from events so distant are ordinarily shifted into the infrared and out of sight, this explosion was so violent that its expansion front approached the speed of light , offsetting the red shift due to the expanding universe and rendering it visible

  British Swift researcher Julian Osborne said yesterday :

" the explosion took place 7.5 billion years ago, the photons have only just reached us. Are the photon's wavelength affected? Yes, the cosmological redshift almost doubled the wavelengths by the time they reached us. (The emitting surface was travelling towards us at a very high fraction of the speed of light however, this causes the pre-cosmologically-redshited photons to have a very much shorter wavelength than they would have in the inertial frame of the emitting surface.

There was no prompt dispersed spectrum obtained unfortunately, although the redshift (and thus distance) was determined from a dispersed spectrum of the afterglow about an hour after the burst. .. were  photons emitted in the visible detected?', then the answer is probably, as the REM Italian IR telescope in Chile pointed at the burst within 43 sec and it was still very bright at that time. "

ON THE BEACH

Mar's  Holden crater, as recently imaged by  by NASA's Mars Reconnaissance Orbiter shows every sign of being a lakefront beach short of a lifeguard stand and a game of volleyball in progress.  It would of course be nice if the water were still there , and  a hundred degrees warmer, ...

The   finely layered  calm water sediments speak for themselves , and  MRO's instruments also detected clay and other wet environment minerals , researchers report in  Geology . They also assert that  lake lasted long enough to be a potentially habitable environment. This puts Holden hugh on the list of  candidate sites for landing  NASA's Mars Science Laboratory in 2010. (Photo: NASA/JPL/University of Arizona)

DARK LIGHT

Dark-field X-rays Dissipate Structural Fog

It used to take an ultra brilliant synchotron x-ray source about as portable as a Swiss  bank vault to provide the high contrast high-quality dark-field scatter images using reflective optics .

Now they have been obtained using conventional X-ray tubes, an advance that could pave the way to revealing micro-cracks in aircraft or boat hulls, bone splinters  and on the analytical side , identifying explosives Pfeiffer et al., Nature Materials.          

A team from Switzerland and Denmark has incorporated a  nanostructured grating interferometer into an X-ray setup that allows brightness and bandwidth restrictions to be overcome.          
Nanostructured gratings permit the use of a broad energy spectrum, including the standard range of energies that are used in traditional X-ray equipment. Current imaging equipment can be adapted to include dark-field imaging data obtained from small-angle scattering, revealing information on the microporous or microcrystalline structure of the material. Another possibility is Lang topographs to fingerprint gemstones.

Potential applications include security screening as explosives with microcrystalline structures can be identified by their ability to scatter X-rays.The literally stark contrast between these  chicken wing images demonstrates the potential of dark-field imaging  in medical applications.

“In cases of complicated bone fractures, where small splinters can intrude into the surrounding tissue, dark-field contrast could provide the necessary specificity to visualize subtle details"

lead author Franz Pfeiffer of the Paul Scherrer Institut, Switzerland, told Nature          

Ring Tones From The Edge

Another dazzling result  debuted at the annual meeting of the American Astronomical Society. The Hubble Space Telescope has recorded a double Einstein ring, a cosmic mirage  arising from the gravitational lensing predicted by Einstein in the theory of general relativity.

Hubble has found a triplet of galaxies  2 , 6  and 11 billion light-years away--lying exactly behind each other in the line of sight from the solar system  The light from the more distant is bent by the gravity of the nearer one, creating  two nested rings. If more double rings are found, spectroscopy  may tell if  the expansion rate of the universe has changed over time.

The Rocket's Black Glare

The two main classes of black holes pose no threat to distant bystanders. Small ones , of a few solar masses  simply sit in the middle of their former solar systems, lit up like lighthouses by infalling matter , and giving fair warning to stay clear.

Giant black holes in galactic centers,like this, the quasar Abel-3, though capable of stellar genocide,devouring or gravitationally  disrupting any stars that  spiral in, are too deep in their own massive gravity wells to be  released by anything short of an inter-galactic  core collision .

But now  astronomers have circumstantial evidence for the existence of a third class that weigh in at a few hundred to a few thousand suns. They might form within dense, spherical swarms of hundreds of thousands of stars known as globular clusters, although no one is sure how.

General relativity dictates that the merger of two black holes produces a burst of gravitational waves,  expanding ripples in spacetime itself. If the merger is eccentric, or if the two black holes spin at different rates or in different directions, gravity  waves emerge asymmetrically,and can act like a rocket on the product of the  black hole merger  flinging it out of the cluster with a velocity of thousands of kilometers per second.

At this weeks  meeting of the American Astronomical Society in Austin Texas   Kelly Holley-Bockelmann of Vanderbilt University reported  that, If intermediate-mass black holes do exist they will be prone to merger, triggering the sort of  gravity wave cusps that could  spit them  out of  the clusters and send them tearing through space at several per cent of the speed of light

Isn't astrophysics wonderful- the worst thing that can happen to the solar system just keeps getting better and better. The good news is that even if hundreds are being generated annually, the odds against our getting clobbered by one of these double barreled monstrosities are a quadrillion to one.

Under the Superdome

A Megatelescope Will Dwell

Thanks to Gordon Moore, astronomical telescope size will continue to double fast as the number of well heeled Silicon Valley foundations. The next generation, scheduled to collect its first light in 2016, is this 100 foot monster

A decade long commitment by his foundation will provide much of the three hundred million dollar cost of developing the Thirty Meter Telescope. The TMT will consist of a primary mirror with 492 individual 1.45-meter segments together measuring 30 meters in diameter, more than eight times the collecting area of the biggest instruments extant, the Keck telescopes in Hawaii. Thanks to Moore's Law, the mirror segments will be under ever more precise computer control  as software and sensors co-evolve, so that they will ever more closely approximate a perfect single mirror. This revolutionary technology was developed for the 10-meter Keck mirrors in the two Keck telescopes in Hawaii

Adaptive optics (AO) will enable the Thirty Meter Telescope to exceed the resolution of the Hubble Space Telescope despite being immersed in the Earth's wobbly ocean of air. The TMT AO system will use six intense metal vapor laser beams to create six glowing pinpoints of light in a layer of sodium atoms sixty miles overhead in the Earth's ionosphere.

These bright artificial stars serve as references for measuring turbulence, allowing the AO system to compensate for blurring of starlight by light path variations in the air. This virtual guide star technology was first used to halt the  twinklingof the stars   through the nearly century old 100 inch Hooker telescope of Los Angeles Lick Observatory, and has since been developed further using  the Palomar 5-meter and  the paired Keck 10-meter telescopes.

The Big Dark

DO DARK DARK STARS EXIST?

Odd things may happen if and when a pre-stellar cloud condenses into the gravity well of a clot of neutralinos

Such a circumstance may have been commonplace shortly after the big bang, for dark matter outweighs the normal sort by a factor of six . Now a paper has appeared calculating the consequences- the  virial theorem predicts heating of the mixture by dark matter annihilation as neutralinos collide may be too great to allow condensation to normal stellar densities, resulting in giants stars that glow without nuclear fusion., kept from igniting by the radiation pressure of annihilation gamma rays within the enormous sphere

Up to 15,000 solar masses , and the size of the Earth's orbit, or larger, these  Dark Matter Stars may stlll be sulking out of observational sight but detectable by their energetic gamma rays-- over 100 gev for nu-nu driven processes

Douglas Spolyar , Katherine Freese and Paolo Gondolo give a preliminary account in a paper available from Arxiv Astrophysics --

http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.0521v2.pdf

and Science has a news report  for subscribers as well

Rhesus Pieces

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Will I Be A Stem Cell's Uncle?
Steve Connor, Science Editor of Britain's Independent has broken the story of a forthcoming Nature article  announcing the successful cloning  of a  rhesus monkey by a group led by Shoukhrat Mitalipov at the National Primate Research Center in Beaverton,Oregon.

Dr Mitalipov's group  has pioneered  primate egg handling techniques that avoid damaging ultraviolet light and fluorescent tags in fusing an egg with a nucleus taken from an adult primate skin cell. This has led to the  creation of dozens of cloned embryos from adult monkeys, which raises the prospect of similar procedures leading to cloned human embryos despite prior efforts plagued by technical problems and charges of research fraud and questionable ethics.

The latest primate work is believed to have involved implanting about 100 cloned embryos into around 50 surrogate rhesus macaque mother , who have not yet succeed in carrying any to term. Dr Mitalipov can't comment on the Nature paper, but told colleagues at a meeting this year that tests on two batches of stem cells from 20 cloned embryos indicated they were true clones. Professor Alan Trounson of Monash University said " This is 'proof of concept' for the primate.

Professor Don Wolf, who led Mitalpov's  laboratory  until recently said.

"We could now produce cloned blastocysts [embryos] in the monkey at a reasonable frequency...It's possible that we're still just having bad luck. We're producing may be one in 20 or one in 30 cloned blastocysts that are 'normal' and capable of producing a pregnancy and we just haven't got them into the animal recipient at the right time to allow implantation and pregnancy to occur,"

"The focus now is going to be on therapeutic cloning and using the non-human primate as a paradigm for therapeutic cloning for what you might be able to do clinically,"

First Light

Non-linear optics has dealt physics another wild card:

Here's part of A.V.Gorbach & D.V. Skryabin's abstract, from Nature Photonics 1, 653 - 657 (1 Nov. 2007)

Light trapping in gravity-like potentials and expansion of supercontinuum spectra in photonic-crystal fibres

 

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Femtosecond pulses of light propagating along photonic-crystal fibres can generate a broad optical supercontinuum ... Among the physical principles underlying supercontinuum generation are soliton emission⁷, a variety of four-wave mixing processes , Raman-induced soliton self-frequency shift
, and dispersive wave generation mediated by solitons...all of the above effects contribute to supercontinuum generation, none of them can explain the generation of blue and violet light from infrared femtosecond pump pulses.

we argue that the most profound role in the shaping of the short-wavelength edge of the continuum is played by the effect of radiation trapping in a gravity-like potential created by accelerating solitons. The underlying physics...has a straightforward analogy with the inertial forces acting on an observer moving with a constant acceleration.

Hot Day On A Cold Comet

Comet Holmes, until last month a dim 3km dustball even as imaged in powerful telescopes, has erupted like a nova, brightening a million fold into naked-eye brilliance in a matter of weeks.

Where did it acquire the energy needed to pop into a cloud the size of Jupiter? An asteroid impact? A satellite body ?

By  an odd coincidence, I weighed in on one new energy storage  mechanism that can lead to comet outbursts far from the warming sun  in a scientific paper in Naturwissenschaften whose basics were  reviewed in Adamant earlier this year.

This is not to imply we yet know what is happening to Comet Holmes which only takes seven years to complete an orbit , but that we have a lot to find out about energetic  phenomena out in the Big Cold-at present, the surface temperature of comet  Holmes is barely high enough to allow ice to sublimate.

Canned light

Now that light has been slowed to a crawl, researches are pondering how to cage photons for life--

Nature Materials 6, 862 - 865 (2007) Published online: 2 September 2007 | doi:10.1038/nmat1994

Dynamic control of the Q factor in a photonic crystal nanocavityYoshinori Tanaka¹, Jeremy Upham¹, Takushi Nagashima¹, Tomoaki Sugiya¹, Takashi Asano¹ & Susumu Noda^1,2

High-quality (Q) factor photonic-crystal nanocavities^{1, 2, 3, 4, 5, 6, 7, 8} are currently the focus of much interest because they can strongly confine photons in a tiny space. Nanocavities with ultrahigh Q factors of up to 2,000,000 and modal volumes of a cubic wavelength have been realized⁸. If the Q factor could be dynamically controlled within the lifetime of a photon, significant advances would be expected in areas of physics and engineering such as the slowing and/or stopping of light^{9, 10} and quantum-information processing^{11, 12}. For these applications, the transfer, storage and exchange of photons in nanocavity systems on such a timescale are highly desirable. Here, we present the first demonstration of dynamic control of the Q factor, by constructing a system composed of a nanocavity, a waveguide with nonlinear optical response and a photonic-crystal hetero-interface mirror. The Q factor of the nanocavity was successfully changed from 3,000 to 12,000 within picoseconds.

SLIMEWIRE

Bacteria , writes Phillip Ball in Nature, "can sprout webs of electrical wiring that transform the soil into a geological battery"

D. Ntarlagiannis et al  report in Geophys. Res. Lett. 34, L17305; 2007, that ome soil bacteria form networks of tiny wires linking individual bacterial cells into a web-like electrical circuit. The wires allow the bacteria to get rid of electrons generated during metabolism, transporting them to distant 'electron dumps'.

This leads Venter research Institute scientist Yuri Gorby to speculate soil may act as a circuit built by microbes to power their metabolic systems,. As the bacteria consume nutrients for energy, they spit out unwanted electrons into the circuit.

Last year, Gorby and his colleagues discovered that Shewanella oneidensis bacteria can grow 100 nanometer ( 1000 atom wide ) filaments  which conduct electricity (Y. A. Gorby et al . Proc. Natl Acad. Sci. USA 103, 11358–11363; 2006). The researchers presented evidence that the microbes use these 'nanowires' to shunt electrons produced during metabolic reactions onto the surface of mineral grains in the soil, to be taken up by metal ions. Without an electron acceptor, the bacteria cannot function properly and die.

Nixes Mate

Last year, the Hubble Space Telescope nearly fried its eye gathering enough off axis photons to reveal Pluto's two new and unsuspected moons, Nix and Hydra.Now  ten images gathered by the adaptive optics of the giant ground-based Keck telescope in Hawaii have been integrated into a clearer view

As to  Hydra, Nix's companion in the Plutonian  suburbs, I hope they leave it off the star charts, lest dyslexic New England astrogators confound it  with  the eponymous rock in Boston Harbor, formerly the site of a gibbet for showing off freshly hanged pirates, quakers and such.

Another Day, Another Cosmology

Astrophysicists Liang Gao and  Tom Theuns have floated an alternative to the theory of primordial matter condensing into star-forming clouds withing clumps of cold dark matter that does not interact with radiation. In their computer model, dark matter can  emit radiation,and radiation pressure would resist clumping forces and cause elongation of dark matter concentrations instead

Their paper in  Science suggests such  warm dark matter would stretch out into  million solar mass filaments kiloparsecs long , attracting  primordial hydrogen and helium gas to form the first stars and nucleate  supermassive black holes in galactic centers.

Cosmic renaissance. This supercomputer simulation shows a primordial star of 100 solar masses, formed inside a dark matter minihalo and surrounded by a bubble of ionizing radiation (light blue). The bubble is embedded in the still-neutral cosmic gas -- an initial step in the process of cosmic reionization.  Volker Bromm notes n Science:

",Their simulations demonstrate how sensitively the formation of the first stars depended on the detailed properties of the still mysterious dark matter."

I's Got Plenty Of Nothing

A Billion Billion Billion Cubic Light-Year Blank

Extragalactic Radio Sources     and the WMAP Cold Spot

a paper that is to appear soon in The Astrophysical Journal by  astrophysicists  Lawrence Rudnick , Shea Brown,and Liliya R. Williams of the U.Minn Department of Astronomy,  reports that  the WMAP microwave background spacecraft has  detected a void in the  universe a billion light years across --

"Our results suggest that the dip in extragalactic brightness and number counts and the WMAP cold spot are physically related, i.e., that the coincidence is neither a statistical anomaly nor a WMAP foreground correction problem... To create the magnitude and angular size of the WMAP cold spot requires a 140 Mpc radius completely empty void... far outside the current expectations of the concordance cosmology, and adds to the anomalies seen in the Cosmic Microwave Background"  Its discovery began as a blank spot in radio telescope maps, but optical surveys saw neither galaxies or stars, and x-ray  telescopes no sign of blackholes, quasars,or even dark matter.

''This is 1,000 times the volume of what we sort of expected to see in terms of a typical void,''   Rudnick told The New York Times  ''It's not clear that we have the right word yet ... This is too much of a surprise.''

The Times reports Rudnick was examining a sky survey from the National Radio Astronomy Observatory, which essentially takes radio pictures of a broad expanse of the universe. But one area of the universe had radio pictures indicating there was up to 45 percent less matter in that region...The rest of the matter in the radio pictures can be explained as stars and other cosmic structures between here and the void, which is about 5 to 10 billion light years away.

Rudnick then checked observations of cosmic microwave background radiation and found a cold spot. The only explanation, Rudnick said, is it's empty of matter.It could also be a statistical freak of nature, but that's probably less likely than a giant void, said James Condon, an astronomer at the National Radio Astronomy Observatory.

The Dark Hole Paradox

This just released image  shows an X-ray view from the orbiting Chandra X-ray observatory overlaid on a visible light image of galaxy cluster Abell 520  The optical  part shows stars in our Milky Way and galaxies belonging to the cluster. The red glow is the x-rays from normal matter heated to millions of degrees in the cluster. The blue denotes  the location of the dark matter in the cluster, inferred by its distortion of the coordinates of background galaxies.

Bad Astonomy Blog  describes how  here

Paradoxically, more dark matter appears near the center of the cluster, where galaxies are few , while some areas where there are lots of galaxies show little dark matter.

This is antithetic to what theory predicts- astronomers are baffled that the collision of the Abell 520 cluster  tore galaxies away from both dark matter (blue) and the x-ray emitting hot gas clouds (magenta). The circles show where astronomers had expected the galaxies to end up.
Credit: NASA/CXC/M. Weiss

And now for some Completely Different Cosmology...

TOAST

In 2005, E. E. Becklin et al reported in The Astrophysical Journal on " A Dusty Disk around GD 362, a White Dwarf with a Uniquely High Photospheric Metal Abundance"  Eighteen years earlier, an infrared excess was discovered associated with the white dwarf G29-38/m .

Now new Keck telescope observations of  GD 362 show a ring of dust inside the  Roche limit of the star, leading to the disconcerting conclusion that the hot white dwarf's metal emission spectrum  arises from its having recently smashed and  swallowed an earth-like planet.   Which former world is, to put it mildly, toast.

The good  news, in Science 's words, is that the" discovery bolsters astronomers' suspicion that solar systems similar to ours must exist around other stars." It notes most white dwarfs

"have atmospheres that consist almost entirely of helium and hydrogen. But GD 362 is different. Using spectrometers attached to the Keck I and II telescopes at Mauna Kea Observatory in Hawaii and to several other telescopes, a team of astronomers including Michael Jura of the University of California, Los Angeles, identified the signatures of 17 elements in GD 362, including sodium, magnesium, aluminum, iron, and nickel... the levels of these elements in GD 362's atmosphere occur in similar proportions as those on Earth...the team reports in an upcoming issue of The Astrophysical Journal.

...says astrophysicist Alan Boss of the Carnegie Institution of Washington, D.C. "It gives us more proof that planetary systems resembling our own are likely to be common in the galaxy, and that life may be commonplace in the universe."

The View From The Bridge

Forget What You've Seen On Star Trek

As  camera pixels grow smaller, telescopic Infrared images of the  sky are growing ever more refined. This new mosaic of the whole Milky Way just released  by Japan's JAXA program, shows energy radiated by the black hole at the galactic center  turning the sky into a horizon to horizon toaster oven.  1.6 and 3.2 gigapixel cameras will render it even more striking in the decade to come.

There's more to relativistic visual effects in space travel than rainbows. High enough speeds can shift wavelengths clear out of the range of human vision--and render the unseen visible. In a realistic view from a starship bridge racing toward the galactic center at near light speed, the familiar  luminosity of the Great White Way could be blue-shifted into ultraviolet invisibility, and the galaxy's central infrared glow might emerge into something very like the tawny image JAXA has assembled .

 

Cold Light and Hot Rocks

If  you are fascinated by the cold blue lights that wink from the latest laptops,recall that color was unobtainable when solid state lighting debuted two decades ago.

It's a wonder that gallium nitride technology exists at all. Light emitting diodes got their start at the red end of the visible spectrum by an arduous process of material improvement. It took decades to perfect the chemistry of growing pure and perfect crystals of a class of light emitting diode materials with the same symmetry as silicon. Getting to  gallium arsenide was hard because arsenic is volatile. It tends to boil off at the temperatures needed to grow crystals  directly from a melt, so it took decades to  perfect it and a class of chemically related crystals , the so called III-V compounds , in ways that allowed the direct conversion of  electrons into photons-- the quantized stuff of light.

Can Exobiology Recapituate Exomineralogy ?

Funded by an effort rooted in science fiction, the  scientific search for extraterrestrial intelligence ( SETI)  began three decades ago.  But searching for  intelligence  is very different from searching for life. SETI asumes we can eavesdrop on distant civilizations talking to themselves , whether as broadcast journalism or the extraterestrial equivalent of the Internet. This human effort has coincided with the dawn of synthetic biology, and some hope that discovering earthly  life's origins will provide insight into how distant intelligences may be embodied. Yet strangely, very little has been done to  discover what  can happen on alien planets in the eons before life evolves.One of their stranger--and more colorful--sights may be metal saturated drops of ammonia rain.

On planets where that happens, crystals of hard to synthesize semiconductors may be as commonplace as those of fools gold are on Earth .

Conditions on Earth scarcely resemble those elsewhere in our own solar system. We live on a wet and tepid exception to the chemical and physical norms of the planets that contain most of the solar sysytems mass. Being made largely of water like the rest of the life on Earth, we think nothing of life's inorganic substrate being the product of wet chemistry- most of the material in the Earths crust has been transformed by interaction with superheated water, often several times over, as the tectonic conveyor belt recycles rocks from the mid-ocean ridges and subducts those at the edges of the continents.

Earthly quartz and feldspars, micas and clays , all contain water and have been re-arranged by it. Likewise, compounds that are decomposed by water and elements that react vigorously with it are largely alien to the surface of the Earth . Not only have we never seen them in the state of nature , but  they scarcely figure in our imagined view of the chemistry that gave rise to life. 19th century mineralogists cataloged species  representing  the entire Periodic Chart long before modern chemistry isolated  most of the elements it contains. Yet no earthly mineralogist is likely to encounter crystals of many of the semiconductor compounds on which modern technology depends - the superheated water  useful for growing quartz crystals would simply decompose transistors or light emitting diodes made of the nitrides , phosphides, and arsenides of metals like aluminum , gallium and indium.

It's A Minimal Life

    Frankenstein Lite:

 It's Alive, more or less.

Tom Knight has always liked to build things from scratch.  I first knew him as one of MIT's Artificial Intelligence Laboratory's foremost firmware hackers,but he has  evolved into a founder of synthetic biology , the emerging discipline that addresses the debugging-- and embodiment--of genetic codes . “I gave it a name at least,” he told Nature at a  Swiss conference last week.

Unlike Systems Biology  or Artificial Life, Synthetic Biology is an engineer's game. Biologists have been building computer models for years , but Syn Bio's goal is to create  new and functional gene sequences, or edit old ones to reduce their encumbrance by  junk or random  DNA sequences that help parse  gene expression, but destabilize the storage and replication of 'useful'  information.  Just as byzantine Windows software doomed early PC's to terminal systems crashes , off-the-shelf DNA also leads to eventual  cellular complications, like death.

The  conference climaxed in a announcement awaited--and feared-- ever since Vitalism went infarct with the synthesis of  urea seven generations ago .  A dead ringer for life has at last been created in the lab.

Having sequenced the tiny genome of Mycoplasma genitalium, Venter Institute  molecular biologists assembled a copy of a vital part of that sequence from Certifiably Not Alive off-the-shelf synthetic amino acids. Stuck inside partially  eviscerated, and hence very dead,  Mycoplasma capsids, the  molecular assembly kick-started the nanocorpses' metabolism. The former cells are once again alive, and by the mycoplasmae's minimalist standards , frisky as the ceiling of the Sistine Chapel.

Unlike Systems Biology  or Artificial Life, Synthetic Biology is an engineer's game. Biologists have been building computer models for years , but Syn Bio's goal is to create  new and functional gene sequences, or edit old ones to reduce their encumbrance by  junk or random  DNA sequences that help parse  gene expression, but destabilize the storage and replication of 'useful'  information.  Just as byzantine Windows software doomed early PC's to terminal systems crashes , off-the-shelf DNA also leads to eventual  cellular complications, like death.

The  conference climaxed in a announcement awaited--and feared-- ever since Vitalism went infarct with the synthesis of  urea seven generations ago .  A dead ringer for life has at last been created in the lab.

Having sequenced the tiny genome of Mycoplasma genitalium, Venter Institute  molecular biologists assembled a copy of a vital part of that sequence from Certifiably Not Alive off-the-shelf synthetic amino acids. Stuck inside partially  eviscerated, and hence very dead,  Mycoplasma capsids, the  molecular assembly kick-started the nanocorpses' metabolism. The former cells are once again alive, and by the mycoplasmae's minimalist standards , frisky as the ceiling of the Sistine Chapel.

His Dark Materials

The Hubble telescope has revealed a bright ring of light from galactic clusters in collision lensed into shape by  'dark matter' .

The ring of background galaxy images , defocused by dark matter's  gravity into a light blue haze , is  2.6 million light-years across. It was found in the cluster CL0024+17, located five billion light-years from Earth. A member of the team that spotted the dark matter ring, said they  unexpectedly found the ring while mapping the distribution of dark matter within the cluster, by observing how its gravity bends the light of more distant background galaxies.  Computer simulations of the gravitatonal refraction reveal that as the clusters collide, the dark matter falls to the centre of the combined cluster and "sloshes" back out. As the dark matter moves out, it begins to slow under the pull of gravity and pile up into the  ripple that left this distinct footprint. The report  has been accepted for publication in Astrophysical Journal.

LAST LIGHT

Will it ruin the neighborhood or save a lot of carbon permits?

Pictures are coming online of the brightest stellar explosion ever recorded. Supernova SN 2006gy used to be  a star some 150 times the mass of our Sun, in a galaxy a quarter billion light-years away.

Its explosion was "so powerful that it may require a new type of mechanism that's been predicted theoretically but never seen before ," says Nathan Smith of UCal Berkeley of images  obtained late last year — by optical telescopes and NASA's orbiting Chandra X-ray Observatory of a superova 100 times brighter than any seen before . The initial explanation was that it was an exploding white dwarf. But for a white dwarf to shine so  would require a surrounding cloud of hydrogen generating x-rays about 1,000 times brighter than those the Chandra telescope detected. Smith's UCal colleague  David Pooley says :
....Is   ETA CARINAE    Too Close For  Comfort ?

"We didn't think we'd see anything like this in the local Universe," Instead of  collapse into a black hole, the intensity of the light emitted suggests an explosion  hot enough for gamma ray protons to turn into electron-positron pairs, that annihilating each other blew the entire star away into space- no black hole or spinning neutron remnant remains. The abrupt pulse of radiation energy overwhelmed the doomed star's gravity and blew upwards of 20 solar masses away and  left behind a cloud spidery as the afterimage of a star shell  detonated on the Fourth of July.

That means that SN 2006gy may provide a unique insight into how the Universe's first generation of stars met their end, says Mario Livio of NASA's Space Telescope Science Institute. Even before SN 2006 gy exploded, the star expelled a lot of mass - several Suns' worth, in an eruption like that now seen spewing from Eta Carinae, a massive star that is all too close to us , at  7,500 light years away in our own galaxy.

SN 2006gy  raises fears that Eta Carinae could detonate in a similar way at any time — tomorrow or a millennium from now. If it does, you can expect to read the newspapers announcing Supernova Two Thousand Whatever by its own light in the middle of the night. Never mind the cosmic ray storm and fried satellites to follow-  Jim Hansen's NASA Goddard  cohorts should rejoice. That much starlight means we  can turn off the streetlights for a month , and spare Gaia tons and  tons of CO2 emission. It will also get rid of that pesky ozone hole- by temporarily destroying the O3 layer entirely. However , one weather proverb may survive in modified form: "Red Sky At Morning : Nitric Acid Rain Warning."

The Man Who Lit The Sun

Carl Freiherr von Weizsäcker      1912 - 2007
Before Hitler's dark star eclipsed the golden age of quantum mechanics, Carl-Frederich von Weizsacker worked on theoretical physics with Werner Heisenberg in Leipzig. In 1935 he derived the eponymous formula for computing the masses of nuclear isotopes , which Lise Meitner and Otto Frisch used to explain that what Otto Hahn had discovered in Berlin in 1938 was the fission of uranium.

In 1938 von Weizsäcker theorized that solar energy was produced by hydrogen fusion, but averred the proton- proton reaction might be too weak to make the sun shine , as it yields a neutrino. Hans Bethe and Charles Critchfield's later calculations demonstrated it works like blazes.

Grisly End To T.Rex Tale

The trouble with sequencing dinosaur DNA is that you have to find some first -- absent refrigeration it tends to go off if left on the fossil shelf for more than an eon or two.

Sequencing  proteins is another matter. Dried gelatin , AKA collagen  glue . can last for ages. Digging into the interior of the femur of a less than usually rotten tempered T. Rex that paleontologists found in a  68 million year old sandstone formation in Montana , molecular biologists have found  still supplecollagen.Their success in sequencing its amino acids could help push the limit  of reptile DNA recovery and amplification  back in time towards the age of the dinosaurs as techniques evolve.

The previous record for protein sequence recovery was set by the same grisly  sort of stringy connective tissue from a roughly quarter million year old mammoth. Seven fragments of protein sequence have been gleaned from the T. rex fossil . This is a long way short of Jurassic Park, which may be just as well. Clawing through the limited information on collagen sequences available , the authors from the American Museum of Natural History have so far determined that T Rex gristle resembles the collagen of chickens.

No lawyers were devoured in conducting the research thus far published, and evidencing professional courtesy , the Board Dining Room of the AMNH has yet to put a plate of  reconstituted T.Rex consomme' in front of the General Counsel.

Diamonds Aren't Forever

At least they're not long for this world in the incandescent interiors of giant planets - or even medium sized ones . Though diamond's melting point rises all the way up to over twice the pressure at the center of the Earth , it nosedives shortly thereafter .

So, suggests a new paper in Nature Materials you should abandon all hope if you drop the Hope Diamond overboard on Neptune  --It's going to melt before it hits bottom, and encounter something even weirder as it sinks:

Because several of the high pressure polymorphs of solid water melt at temperatures higher than its Earthly boiling point , the forlorn Hope may encounter a lot of hot ice on the way  down.

Laser-shock compression of diamond and evidence of a negative-slope melting curve Stéphanie Brygoo , Emeric Henry et al.

"In spite of its fundamental and planetary importance, the stability domain of this strong covalent material is largely unknown. After decades of experimental efforts, ... Accurate Hugoniot data of diamond exist up to 590 GPa.  Higher-pressure measurements along the diamond Hugoniot have recently been achieved by laser shocks, showing that diamond probably melts to a conducting fluid.

We report here laser-shock Hugoniot data across the melting transition. The shocked diamond crystal begins to melt around 750 GPa. Furthermore, a negative volume discontinuity at melting is observed. This requires a negative melting slope and thus supports the existence of a maximum on the diamond melting curve...the stability domain of the diamond crystal is now constrained in a relevant region for Uranus-like planetary interiors.

Back After 400 Years: The New Moon

Galileo's own llustrations of the Moon’s surface as he saw it through his telescope have come to light after four centuries and were unveiled this week at Padua University. The five watercolours , showing the Moon with ochre highlighting of  its craters and valleys are in Galileo’s own copy of  Sidereus Nuncius (The Starry Messenger) , helped overturn the belief that the Sun revolved around the Earth ,and provoked a show-down with the Vatican that saw the scientist imprisoned for heresy. They do not feature in any other copy of the book.

They were authenticated by Professor Horst Bredekamp, head of the Art History Institute at Humboldt University in Berlin, and Professor William R. Shea, who holds the Galileo Chair of the History of Science at Padua.

“I initially suspected that they were forgeries" Bredekamp said. “But when I realised after close examination and tests that they were authentic, I was overcome with emotion.”  Shea said that he had been contacted by Richard Lan, an art dealer in New York, for help in authenticating the book, which was published in Venice in 1610. Mr Lan would only say that it had turned up in a collection in South America.

Pop Goes The Boson

At long last , Europe's Large Hadron Collider is ready to accelerate particle beams to unprecedented energies- high enough to pop the virtual Higgs boson that embodies the Weak Force responsible for radioactive decay out of the vacuum in which it lurks. B ut  not all physicists are happy at the prospect. Science reports :

" At the energies the LHC will reach, the standard model goes haywire, spitting out negative probabilities and other nonsense. So the collider has to cough up something new, researchers say. If it spits out only the Higgs, however, the new golden age of discovery could end as soon as it begins.

If the lone Higgs has just the right mass--about 190 times the mass of a proton--it would tie up the standard model's loose ends and leave physicists even more thoroughly stymied than before, says Jonathan Ellis, a theorist at CERN. "This would be the real five-star disaster,"

WRIT IN STONE

Science 9 March 2007:Vol. 315. no. 5817, pp. 1365 - 1366   Letters
Did the Olmec Know How to Write?
In their Research Article "Earliest writing in America" (15 Sept. 2006, p. 1610), Ma. del Carmen Rodríguez Martínez et al. suggest that the inscribed "Cascajal block" is the first discovery of Olmec writing. Although we agree with the authors that it is possible that the Olmec did write, we have strong reservations concerning this artifact and its incised motifs.

1) Being found by persons unknown in a pile of bulldozer debris does not constitute reliable provenance.

2) The block does not fit any known category of Mesoamerican inscribed artifact; it is not a stela, celt, sculpture, or jewel. The heartland Olmec did not build in stone; therefore, it cannot be an architectural inscription. Indeed, there are many hundreds of similar serpentine blocks known at La Venta that were used as basal ornament on earthen platforms and in the buried pavements, but not a single one of these has engraving or relief carving. The authors' musings about the block being used for practice and repeatedly erased (resulting in a concave surface) are farfetched.

3) Known Mesoamerican writing systems are written either vertically or linearly (or a combination of the two, as in Maya glyph blocks); they do not randomly "bunch" glyphs as on the Cascajal block [c.f. (1)].

4) Many of the so-called glyphs replicate decorative motifs found on a wide range of largely unprovenanced (i.e., their authenticity is not proven, nor can it be proved) small-scale artifacts. None of these motifs in their original context has been identified as a form of writing. For example, "glyph" # 2/24/38/52 is found as part of the headdress assemblage on a number of the celts (nos. 116, 117, 118, 119) reproduced in Olmec Art of Ancient Mexico (2); "glyph" # 28/58 is found on another celt (no. 114), and "glyph" # 4 is inscribed on a stone figure (no. 47) again in the same catalog.

5) What we can only describe as the "cootie" glyph (# 1/23/50) fits no known category of Mesoamerican glyph and, together with the context of the discovery, strongly suggests a practical joke.

Karen O. Bruhns San Francisco State University ; Nancy L. Kelker Middle Tennessee State University

Response
We thank Bruhns and Kelker for articulating several issues that others have raised concerning the Cascajal block and for providing us the opportunity to lay them to rest.

1) The provenance of the block is what it is, reported by nonarchaeologists but still fixed to an area of a few square meters within a known archaeological site in Veracruz, Mexico. Many other bona fide examples of ancient writing have even less secure find spots, including every known example of Mesoamerica's Isthmian Script and Egypt's Rosetta Stone. Such objects will continue to appear in the future, and each will require careful study for evidence of reliability. We have done this to the extent of our ability with the Cascajal block and stand by our considered and, to most scholars, valid assessment that it is a key addition to the corpus of inscriptions in Mesoamerica.

2) The authors claim that "[t]he heartland Olmec did not build in stone; therefore, it cannot be an architectural inscription." Then, in their next sentence, they cite precisely such architectural ornaments at the Olmec site of La Venta. We now suspect that the block may have served such a function. Such texts, especially from coastal Veracruz and the Maya region, characteristically are executed in shallow lines. Indeed, the celebrated La Mojarra Stela 1, found in circumstances much like those of the Cascajal block, was housed in the Museo de Antropología, Xalapa, for more than a year before anyone noticed the more than 500 glyphs on its face. It took some further time to see that an additional text appeared on its side, this on a sculpture under exceptionally thorough scrutiny (1). Therefore, we would not be surprised to learn that other previously discovered examples went unnoticed.

3) The signs form purposeful sequences; they do not "randomly 'bunch,' " as Bruhns and Kelker assert. The patterns in the Cascajal text are spelled out carefully in our paper.

4) The block contains signs found on objects with provenance and others that lack it. Some of the latter have been known since the 19th century (i.e., the "Humboldt Celt") (2). One previously unknown sign (glyph 19) appeared years after the discovery of the block in a secure archaeological context at Canton Corralito, Chiapas, Mexico (3). All known hieroglyphic systems in the world relate to pre-existing iconography or codified symbolism; new signs appear when warranted by scribal needs. Any hieroglyphic system that deviated from local iconography would be not only unique but, indeed, an inexplicable phenomenon.

5) If the "insect glyph" was a practical joke, the jokester was an Olmec. The motif is shown three-dimensionally in the diminutive Monument 43 at San Lorenzo, discovered and excavated by one of us (Coe) in 1966 and published by Coe and Diehl in 1980 (4).

We reject the author's specific criticisms and their implicit claim that the block is a modern forgery. However, we appreciate the fact that such challenges are the essence of scientific enquiry and that they eventually lead to truth. We still affirm that the Cascajal block is the oldest example of writing in the New World and among the most important finds ever made in Mesoamerica.

Ma. del Carmen Rodríguez Martínez
Centro del Instituto Nacional de Antropología e Historia Veracruz, Mexico

Ponciano Ortíz Ceballos
Instituto de Antropología de La Universidad Veracruzana , Xalapa, Mexico

Michael D. Coe
Professor Emeritus , Yale University

Richard A. Diehl
Department of Anthropology , University of Alabama

Stephen D. Houston
Department of Anthropology , Brown University

Karl A. Taube
Department of Anthropology University of California Riverside

Alfredo Delgado Calderón
Centro del Instituto Nacional de Antropología e Historia ,Veracruz, Mexico

Less than meets the eye

There is less to this Nature cover than meets the eye.

Though atomic force microscopy  crisply shows the difference between small silicon, medium sized tin and large lead atoms in an alloy crystal, this ten nanometer wide field of view affords no clue as to whether those atoms are relatively light or heavy.

There are two stable isotopes of siicon, nine of tin and four of lead, and despite this visual tour de force of size resolution, atomic force microscopy still lacks the finesse to feel the difference between neutron rich and neutron deficient atoms of the same element. 

The Biggest Picture

Here is the first map of  most of the mass in the observable universe.
New techniques allow the drawing of contours between regions of equally weak gravitational lensing of distant galaxies, caused by intervening distortion of spacetime by dark matter drawing ordinary matter after it . This may have formed  the  filament and clump structures whence star and galaxy evolution proceeded not too long after the Big Bang. Details in this week's Nature, Nobel prize coming soon to a decade near you.

Hot stuff in the Big Cold

A HOT DAY ON ENCELADUS

 As much as we love natural history , we hold  environments that would kill us in short order in limited esteem. Living on the Earth’s well-shielded surface ,at the bottom of a virtual ocean of air,  we rarely encounter materials that have suffered the ravages of irradiation in the vaccum of deep space We're used to a fraction of one rad a year of background radiation, , but the state of nature elsewhere in the solar system is far more hostile ,including the moons of its giant planets.

 Jupiter and Saturn have immense magnetospheres , and radiation belts that are to  Earth's Van Allen belt as a blast furnace is to a toaster oven. Close to Jupiter, space  is filled with particles enough to deliver up to 10 rads an hour , and the thousand rad flux on Europa would  deliver enough Grays (Joules of absorbed ionizing energy) to bring you to death's door in an hour.

On Saturn’s moon  Enceladus, the environment is almost as hostile, because while Saturn traps solar wind ions and electrons at a somewhat lower density,  its  moons sweep up  disproportionate amounts of radiation damage because  its magnetosphere can trap energetic solar wind particles for years, and focus cosmic rays, amplifying the particle flux. If cells perish in hours out in the ionizing heat of the Big Cold, what happens to inorganic dust exposed over geological time? to find out,  Read on, or take a look at  Seitz et al: 'Xenomict energy in cold solids in space' Naturwissenschaften, March 2006

Feeling Really Jaded

                                           The Hunt for Olmec Blue

To undo the mischief wrought by Stephen Spielberg and Angela Jolie, Archaeology students must be carefully  taught the work is about as romantic as Certified Public Accounting , focused on digging up data in dusty archives , not loot in tropical jungles. Yet this anti-cliche has its problems - neat stuff  does end up underground , and lost mines ,and languages somehow manage to  get lost . 

And found -- Karl Taube   with whom  I've written on the Olmec  mines discovery in Antiquity, and in the most recent monograph from Harvard's Dumbarton Oaks-    http://www.doaks.org/OlmecArt.pdf
has just published another major Olmec find in Science, 5 September, P 1610 :

Oldest Writing in the New World