NEWS THREAD 3

[towhom]

Fast Growth Increases the Selective Advantage of a Mutation Arising Recurrently during Evolution under Metal Limitation
PLoS Genetics
Received: May 20, 2009; Accepted: August 17, 2009; Published: September 18, 2009
www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1000652;jsessionid=34D64D2EAABF543E16AB5DD9246470AF

Abstract
Understanding the evolution of biological systems requires untangling the molecular mechanisms that connect genetic and environmental variations to their physiological consequences. Metal limitation across many environments, ranging from pathogens in the human body to phytoplankton in the oceans, imposes strong selection for improved metal acquisition systems. In this study, we uncovered the genetic and physiological basis of adaptation to metal limitation using experimental populations of Methylobacterium extorquens AM1 evolved in metal-deficient growth media. We identified a transposition mutation arising recurrently in 30 of 32 independent populations that utilized methanol as a carbon source, but not in any of the 8 that utilized only succinate. These parallel insertion events increased expression of a novel transporter system that enhanced cobalt uptake. Such ability ensured the production of vitamin B₁₂, a cobalt-containing cofactor, to sustain two vitamin B₁₂–dependent enzymatic reactions essential to methanol, but not succinate, metabolism. Interestingly, this mutation provided higher selective advantages under genetic backgrounds or incubation temperatures that permit faster growth, indicating growth-rate–dependent epistatic and genotype-by-environment interactions. Our results link beneficial mutations emerging in a metal-limiting environment to their physiological basis in carbon metabolism, suggest that certain molecular features may promote the emergence of parallel mutations, and indicate that the selective advantages of some mutations depend generically upon changes in growth rate that can stem from either genetic or environmental influences.

Author Summary
Effects of mutations can change under different genetic backgrounds or environmental factors, also known as epistasis and genotype-by-environment interactions (G×E), respectively. Though epistasis and G×E are traditionally treated as distinct phenomena, our study of a beneficial mutation highlights their commonality. This mutation resulted from insertion of the same transposable element upstream of a novel cobalt transport system in 30 of 32 independent populations during evolution in metal-limited media. The resulting increased cobalt uptake provided a selective benefit that depended upon two environmental factors: cobalt limitation and growth substrates whose metabolism requires a particular vitamin B₁₂ (which contains cobalt) -dependent biochemical pathway. Furthermore, this mutation exhibited epistatic and G×E interactions with other cellular processes in a generic way, such that its selective advantage increased as cells were able to grow faster. This growth-rate dependence accords with a simple model: the slowest of multiple physiological processes needed for growth exerts the greatest control over an organism's growth rate. It suggests that as growth results from the performance of the entire physiological system, genes or environmental factors that affect distinct physiological processes may thus interact through their convergent effects on growth phenotypes.

Complete article available for download at the link displayed above.

This is an interesting article.

[towhom]

Testing the link between terrestrial climate change and Galactic spiral arm transit
arXiv
Andrew C. Overholt, Adrian L. Melott (University of Kansas), Martin K. Pohl (Iowa State University)
[v1] Mon, 15 Jun 2009 19:59:50 GMT
[v2] Wed, 16 Sep 2009 20:23:52 GMT (this is v2)
Subjects: Galaxy Astrophysics (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph); Geophysics (physics.geo-ph); Populations and Evolution (q-bio.PE)
arxiv.org/abs/0906.2777

Abstract
We re-examine past suggestions of a close link between terrestrial climate change and the Sun's transit of spiral arms in its path through the Milky Way galaxy. These links produced concrete fits, deriving the unknown spiral pattern speed from terrestrial climate correlations. We test these fits against new data on spiral structure based on CO data that does not make simplifying assumptions about symmetry and circular rotation. If we compare the times of these transits to changes in the climate of Earth, not only do the claimed correlations disappear, but also we find that they cannot be resurrected for any reasonable pattern speed.

Complete article available for download at the link displayed above.

[poeteanglais]

@ Towhom: Thanks for the extract of congresswoman Carol Shea-Porter's newsletter. Puts the whole d**n argument into perspective, doesn't it. I must say, I thought as much.

Blessings and light to all

[towhom]

Ganymede Makes Big Impression On Jupiter's Auroral Lightshows
ScienceDaily
Sep. 19, 2009
www.sciencedaily.com/releases/2009/09/090916223913.htm

Studies of features in Jupiter’s spectacular and rapidly changing aurorae have given new insights into the complex electromagnetic interactions between the giant planet and two of its innermost moons.

As Ganymede and Io orbit Jupiter, they interact with regions of plasma and generate electromagnetic waves that are projected along Jupiter’s magnetic field lines towards Jupiter’s poles where they cause auroral bright spots. Scientists from the University of Liège in Belgium have used thousands of images taken by the Hubble Space Telescope in ultraviolet wavelengths to monitor these auroral features in unprecedented detail.

“Each of these auroral structures is telling an ongoing story about vast transfers of energy taking place far away from the planet. By analysing the exact locations of these features and how their shape and brightness changes as Io and Ganymede move in their orbit around Jupiter, we have created the most detailed picture to date of how Jupiter and these moons are electromagnetically interconnected,” said Dr Denis Grodent, who will be presenting results at the European Planetary Science Congress in Potsdam, Germany, on Thursday 17 September.

Uniquely amongst Jupiter’s moons, Ganymede has a strong enough magnetic field to carve a protective magnetic bubble within Jupiter’s powerful magnetosphere. Analysis of the Hubble images by Grodent and his colleagues has allowed them to measure accurately the size of the Ganymede auroral footprint for the first time. They have found that it is too big to be a simple projection of Ganymede’s cross-section. However, using a three-dimensional computer model to map the footprint back along the field lines, the team has found that it corresponds well with the diameter of Ganymede’s mini-magnetosphere.

In addition, the sequences of Hubble images revealed unexpected brightness variations of Ganymede’s auroral footprint at three different timescales: 100 seconds, 10 to 40 minutes, and 5 hours.

“Each of these timescales appears to refer to a specific aspect of the Ganymede-Jupiter interaction and allows us to identify possible actors of this interaction. The 5 hour variation appears to be linked to the rotational period of Jupiter’s magnetic field and the movement of Ganymede through the tilted plasma sheet that surrounds the planet. The 10-40 minute variations could be due to sudden changes in energy due to plasma being injected into the system and the 100 second pulses may be linked to bursts of magnetic energy being suddenly released when Jupiter and Ganymede’s magnetic field lines connect. However, we are not sure at this stage,” said Dr Grodent.

The team has also mapped the positions of all possible locations of the auroral footprint of Jupiter’s volcanically active moon, Io, with unprecedented accuracy. Io’s footprint consists of a series of spots and a long tail that swirls out about 30 000 km in the direction of the planet’s rotation. The angle of observation in some of the Hubble images has allowed the team to measure the altitude of the tail for the first time with accuracy.

“We found that the tail is at an altitude of approximately 900 km above Jupiter’s cloud tops. Interestingly, although the brightness of the tail decreases as it gets further away from the main spot, the altitude remains relatively constant. We also saw spectral absorption indicating that methane is present, which is unexpected at such a high altitude,” said Dr Bertrand Bonfond.

Io’s footprint arises as a result of the moon’s motion through a doughnut-shaped torus of charged particles, which accumulates along Io’s orbit from material ejected by its volcanoes. In this flow of particles Io acts as a boulder in a stream, generating powerful waves that propagate towards Jupiter's poles. These waves have the special property to project electrons in both directions along the magnetic field lines and when these electrons finally hit Jupiter's atmosphere they create aurora in the form of luminous spots. In addition, Io drags on the plasma, briefly slowing it down, and when the plasma is reaccelerated to normal speed it generates electric currents that form the tail.

The team’s analysis shows that the charged particles that generate Io’s auroral features have a wide range of energies, meaning that some electrons penetrate deep into the atmosphere while others lose most of their energy in the upper atmosphere.

Adapted from materials provided by Europlanet Media Centre, via AlphaGalileo.

[towhom]

Gates lashes out at critics of U.S. missile plan
NewsDaily
Posted 2009/09/19 at 8:07 pm EDT
www.newsdaily.com/stories/tre58j002-us-usa-shield-gates/

WASHINGTON, DC — U.S. Defense Secretary Robert Gates on Saturday lashed out at critics of a new missile defense plan for Europe and insisted it was not a concession to Russia, as some charge.

Gates, a Republican who served in senior positions under former President George H.W. Bush and his son, former President George W. Bush, wrote in an opinion article for the New York Times that the criticism of the plan is misguided.

"I believe this is a very pragmatic proposal. I have found since taking this post that when it comes to missile defense, some hold a view bordering on theology that regards any change of plans or any cancellation of a program as abandonment or even breaking faith," Gates said.

The objective of the missile plan is to counter the threat of missile attack from Iran, not Russia.

The Bush plan was intended to intercept long-range Iranian missiles, but Iran has yet to develop long-range missiles and U.S. intelligence recently determined that Tehran is unlikely to have such missiles until between 2015 and 2020.

As a result, Gates changed the plan to counter the possibility of short- and medium-range missiles.

Moscow had protested the Bush plan because it would be based in the Czech Republic and Poland. Leaders in the Czech Republic and Poland had found comfort in the Bush plan because they saw it as some protection against nearby Russia.

Under Obama's new plan, the United States would initially deploy ships with missile interceptors and in a second phase would field land-based defense systems.

Since the plan was announced, Gates has been taking fire from Republicans as well as many military analysts. Democrats and arms control experts have welcomed the plan.

Senate John McCain, ranking Republican on the Senate Armed Services Committee, called the new plan "misguided" and said it was a concession to Russia and an abrogation of an agreement between the United States, the Czech Republic and Poland.

Gates, however, said it was "a better way forward" and argued that Europe will still have missile defense under it. He said it was a distortion to call the new plan "some sort of concession to Russia."

"Russia's attitude and possible reaction played no part in my recommendation to the president on this issue. Of course, considering Russia's past hostility toward American missile defense in Europe, if Russia's leaders embrace this plan, then that will be an unexpected -- and welcome -- change of policy on their part," he said.

Misguided, huh...

Just how many nuclear "anythings" do we really need? We probably have enough "weaponry" to disintegrate the entire planet.

That's "misguided". It's also "stupid".

Another "skewer tactic" from "Goober-R-Us". After all, much of their accumulated wealth and power was and still is based on "War Economics" and "Control through Conflict Instigation".

A quote from the movie "Armageddon":

"GET OFF THE NUCLEAR WARHEAD...NOW"

You people protesting the reduction of these armaments have "Nukes-on-the-Brain" disease...

[towhom]

Coldest Place in Solar System: Our Moon
Discovery News
June 18, 2009
dsc.discovery.com/news/2009/09/18/coldest-moon.html

Astronomers have found the coldest spot in our solar system and it may be a little close for comfort. It's on our moon, right nearby. NASA's new Lunar Reconnaissance Orbiter is making the first complete temperature map of the moon. It found that at the moon's south pole, it's colder than far away Pluto. The area is inside craters that are permanently shadowed so they never see sun.

"It's sort of like a faint glow and that's your only source of heat," said David Paige, a University of California, Los Angeles, scientist who is part of the NASA team. "Right here in our own backyard are definitely the coldest things we've seen in real measurements."

Temperatures there were measured at 397 degrees below zero. That's just 62 degrees higher than the lowest temperature possible.

Pluto is at least a degree warmer even though it is about 40 times farther away from the sun.

The coldest temperatures on the moon were usually in craters that were within bigger craters, hiding farther from the sun, Paige said. Three craters where the cold temperatures were noted were Faustini, Shoemaker and Haworth. And some of the coldest places are so remote and unexplored they don't even have names yet, he said.

Soon, the moon's south pole will slightly warm up with the change of seasons and the north pole will get chillier, he said.

That ultra-cold temperature is important because it can trap volatile chemicals, such as water and methane, said NASA probe project scientist Richard Vondrak. Trapped volatiles would give any future astronauts resources to mine and could help scientists understand more about the origin of the early solar system, he said.

The moon probe, only a week into its science mission, has also found lots of indications of hydrogen, which could indicate trapped ice below the moon's surface, Vondrak said.

While NASA has been to the moon with astronauts and explored it many times decades ago, this is the first close-up look in about a decade and is focusing on the tantalizing south pole, where there is the best chance for hidden ice.

"It's unexplored," Paige said. "Nobody's seen what it's like in these areas before at this resolution."

And the closer NASA's instruments look at the craters, the more nuanced they look.

"The moon is not just a billiard ball with dimples," Paige said. "It's got interesting cracks and crevices."

This is interesting - especially since they're (NASA) releasing the information NOW and it's dated June 18, 2009. It could be a typo - but given the source, it could also be another "timely" release from the "Space Guys"...

[towhom]

Merck backs $150M vax developer in India
FierceBiotech
September 17, 2009 — 11:24am ET
www.fiercebiotech.com/story/merck-backs-150m-vax-developer-india/2009-09-17

The Wellcome Trust in the U.K. and pharma giant Merck are joining forces to fund a $150 million non-profit vaccine developer to be based in India. The new joint venture will focus on developing inexpensive jabs for use in developing countries. And researchers will pursue a special focus on high-risk vaccine programs for neglected diseases.

"The center will bring the scientific and technical skills of an extremely advanced vaccine company like Merck to bear," says Marie-Paule Kieny, vaccine-research director at the World Health Organization. It will also operate as an independent outfit, able to ink development pacts with other companies, researchers in academia, philanthropies and government agencies.

For now, the backers are concentrating on finding a site in India for the new company. Once in operation, the researchers will also be free to focus on near-term opportunities, such as improving existing vaccines.

Here's the release
Read the report from Nature

Now look at this article:

No H1N1 vaccine contracts for India
FierceVaccines
August 28, 2009 — 4:32pm ET
www.fiercevaccines.com/story/no-h1n1-vaccine-contracts-india/2009-08-28

Some are questioning India's response to the swine flu pandemic. While many countries have been buying up vaccines before they have even been produced, Indian officials continue to watch from the sidelines, the Times of India reports. "Indian health authorities have failed to move fast enough," according to the publication.

The Indian government has not signed a single contract for swine flu vaccines with foreign or domestic manufacturers, which include Serum Institute, Panacea Biotec, Bharat Biotech and Cadila Pharma (which is developing a vaccine in collaboration with Rockville, MD-based Novavax). ‘‘No talks have been held with procurement agencies regarding their plans of stockpiling the vaccine, including the quantity required and target group of population," Serum Institute executive director SS Jadhav told the Times of India. As a result, Indian manufacturers are unsure of the amount of vaccine they should produce.

‘‘We have asked global companies like Novartis to include Indians in their clinical trials to test efficacy of the vaccine on our population. We are waiting for their reply," said Dr. Vishwa Mohan Katoch, secretary of India's department of health research.

Here's the TOI article

[towhom]

Sept 19, 2009 14:16:11 GMT 4 @poeteanglais said:

@ Towhom: Thanks for the extract of congresswoman Carol Shea-Porter's newsletter. Puts the whole d**n argument into perspective, doesn't it. I must say, I thought as much.

Blessings and light to all

Hello poeteaglais,

Check this article out...from Senator Baucus' home state (Montana):


Who Does Senator Baucus Listen To
Physicians for a National Health Care Program (PNHP)
Posted on January 26, 2009
Unions for Single Payer Health Care
January 25, 2009
www.pnhp.org/news/2009/january/who_does_senator_bau.php

Montana Senator Max Baucus, Chairman of the Senate Finance Committee, has said that in writing his new healthcare legislation “everything is on the table” except single payer. One wonders if Senator Baucus has been reading his home state newspapers or just listening to the lobbyists for the private insurance industry. (www.Opensecrets.org).

After Baucus ruled single payer “off the table” in his search for an “American” solution to the healthcare crisis, Montana’s newspapers have carried several articles calling for Senator Baucus to put single payer back on the table.

Writing in “The Great Falls Tribune” under the headline “Tell Sen. Baucus Single-payer Should Be On the Table,” Gene Fenderson, who served for twenty-five years as a union trustee of a Taft-Hartley joint healthcare fund, wrote: “I maintain that a single-payer system must be on the table because it can help save our present and future economic well being as a state and nation.” Fenderson criticized the Baucus plan directly saying: “Unfortunately, the Baucus plan simply adds even more layers of confusion to this hodgepodge, which is already driving costs up and up for all Americans. We can do better. We must do better. That is why a single-payer system must be on the table.”

Fenderson concluded: “We need real change in health-care and we need it now. Please join me in urging Sen. Baucus, all of our congressional delegation and President-elect Obama to keep single-payer on the table and a part of the discussion.”

www.greatfallstribune.com/apps/pbcs.dll/article?AID=/200901050500/OPINION/901050304

As if to add emphasis to Fenderson’s argument, a second article, this time in the Helena Independent Record, reported on results of meetings held throughout Montana at the urging of President Obama’s healthcare transition team. The meetings were to report to the transition team what ordinary citizens think about healthcare reform.

“The consensus of (our group) was that we did not see a lot of change coming unless we went to a single-payer, universal health system,” said Deborah Hanson of Miles City, who organized a meeting of local citizens at the behest of Obama’s transition team. “That was sort of a general consensus - knowing, of course, that may not happen.”

“The Miles City meeting, held Dec. 21 at Hanson’s home, was one of several in Montana and thousands held across the nation during the last two weeks of December.”

www.helenair.com/articles/2009/01/07/top/53lo_09017_healthcare.txt

Meanwhile, back in Washington, Senator Baucus was attending a lavish pre-inaugural ball at a posh nightclub where he told Brian Ross of ABC News that “lobbyists just want what’s best for America.” Baucus also had praise for the drug, insurance and other lobbyists who paid for the party, saying: “They really care about our country.”

abcnews.go.com/Video/playerIndex?id=6694754

So the question remains. Who does Senator Baucus listen to?

Call, write or Fax Senator Baucus and tell him single payer should be on the table and should be given a full and fair hearing by the Senate Finance Committee.

Senator Max Baucus
511 Hart Senate Office Bldg.
Washington, D.C. 20510
[phone](Office)
[phone] (Fax)

I guess he's suffering from "Funderferous Oral Flatulence". This "illness" targets the pocketbooks of those "infected" and triggers outrageous statements that are proportional to the bulge of one's campaign contributions and their contributors.

[towhom]

Resolving the network synchronization landscape: Compensatory structures, quantization, and the positive effect of negative interactions
arXiv
Takashi Nishikawa, Adilson E. Motter
[v1] Tue, 15 Sep 2009 20:26:26 GMT
Subjects: Disordered Systems and Neural Networks (cond-mat.dis-nn); Adaptation and Self-Organizing Systems (nlin.AO)
arxiv.org/abs/0909.2874

Abstract
Synchronization, in which individual dynamical units keep in pace with each other in a decentralized fashion, depends both on the dynamical units and on the properties of the interaction network. Yet, the role played by the network has resisted comprehensive characterization within the prevailing paradigm that interactions facilitating pair-wise synchronization also facilitate collective synchronization. Here we challenge this paradigm and show that networks with best complete synchronization, least coupling cost, and maximum dynamical robustness, have arbitrary complexity but quantized total interaction strength that constrains the allowed number of connections. It stems from this characterization that negative interactions as well as link removals can be used to systematically improve and optimize synchronization properties in both directed and undirected networks. These results extend the recently discovered compensatory perturbations in metabolic networks to the realm of oscillator networks and demonstrate why "less can be more" in network synchronization.

Complete article available for download in multiple formats at the link displayed above.

[towhom]

Direct search for exact solutions to the nonlinear Schroedinger equation
arXiv
Wen-Xiu ma, Min Chen
[v1] Thu, 17 Sep 2009 22:05:30 GMT
Subjects: Exactly Solvable and Integrable Systems (nlin.SI); Pattern Formation and Solitons (nlin.PS)
arxiv.org/abs/0909.3330

Abstract
A five-dimensional symmetry algebra consisting of Lie point symmetries is firstly computed for the nonlinear Schroedinger equation, which, together with a reflection invariance, generates two five-parameter solution groups. Three ansaetze of transformations are secondly analyzed and used to construct exact solutions to the nonlinear Schroedinger equation. Various examples of exact solutions with constant, trigonometric function type, exponential function type and rational function amplitude are given upon careful analysis. A bifurcation phenomenon in the nonlinear Schroedinger equation is clearly exhibited during the solution process.

Complete article available for download in multiple formats at the link displayed above.

[towhom]

Impact of Epistasis on Evolutionary Adaptation
arXiv
Bjorn Ostman, Arend Hintze, Christoph Adami (Keck Graduate Institute)
[v1] Fri, 18 Sep 2009 19:00:26 GMT
Subjects: Populations and Evolution (q-bio.PE)
arxiv.org/abs/0909.3506

Abstract
Background
Evolutionary adaptation is a process where a population increases its “fit” to the world it inhabits, and is often likened to climbing a hill or peak. While this process is trivial for fitness landscapes where each mutation provides an advantage (or disadvantage) to the organism that is independent of the fitness effect of a mutation on a different locus, the interaction between mutations (epistasis) is crucial in complex and realistic fitness landscapes.

Methodology/principal findings
We investigate the impact of epistasis on adaptive evolution in a multiplicative NK model, by evolving a population of asexual haploid organisms with circular binary genomes of length N, where each locus interacts with K neighbors. We use a quantitative measure of epistasis and find that epistasis is a monotonically increasing function of K. At high mutation rates selection favors epistatic interactions between mutations, whereas at low mutation rates epistatic interactions hinder adaptation, and are selected against. Higher fitness is attained when more epistatic interactions are possible, with an optimum at an intermediate amount of epistasis. Increasing epistasis transforms the fitness landscape from smooth to rugged, and it is this ruggedness that enables mutations to have a larger fitness effect compared to non-epistatic landscapes.

Conclusions/Significance
When the environment changes and the population finds itself at a suboptimal location of an epistatic landscape, the interactions between loci enables the population to increase fitness drastically with only a few mutational steps. Crossing valleys between peaks in the fitness landscape requires deleterious mutations, which then become essential for adaptation by interacting with subsequent mutations. Because of this sign epistasis, both deleterious and beneficial mutations contribute to adaptation, underscoring the benefit of initially deleterious mutations and epistasis in adaptive evolution.

Author Summary
Fitness landscapes are the result of the interaction of genomes with the environment, via the organisms that the genomes give rise to. Depending on the complexity of the environment and the encoding of information in the genome, these landscapes can be very complex. Darwinian adaptation can be viewed as a walk within that landscape that attempts to find the highest peaks. Whether or not these peaks can be found depends on the ruggedness of the landscape, a feature that is determined by the degree of interaction between genes, a phenomenon called epistasis. In a computational model of evolution in a fixed landscape with a tunable amount of epistasis, we find that the degree of epistasis has a profound influence on the dynamics of adaptation. In landscapes with more epistasis, the average number of mutations that are necessary to reach high fitness is lower, but each mutation itself is more beneficial on average, so that the attained fitness is also higher. Epistatic interactions between mutations make it possible for genomes to cross fitness valleys, an effect that is more pronounced for higher mutation rates. Too much epistasis, on the other hand, leads to the segregation of the population on suboptimal peaks.

Complete article available for download in multiple formats at the link displayed above.

[towhom]

Experimental demonstration of associative memory with memristive neural networks
arXiv
Yuriy V. Pershin, Massimiliano Di Ventra
[v1] Mon, 18 May 2009 17:16:03 GMT
[v2] Fri, 18 Sep 2009 16:00:11 GMT [this is version 2]
Subjects: Neurons and Cognition (q-bio.NC); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Molecular Networks (q-bio.MN)
arxiv.org/abs/0905.2935

Abstract
When someone mentions the name of a known person we immediately recall her face and possibly many other traits. This is because we possess the so-called associative memory, that is the ability to correlate different memories to the same fact or event. Associative memory is such a fundamental and encompassing human ability (and not just human) that the network of neurons in our brain must perform it quite easily. The question is then whether electronic neural networks (electronic schemes that act somewhat similarly to human brains) can be built to perform this type of function. Although the field of neural networks has developed for many years, a key element, namely the synapses between adjacent neurons, has been lacking a satisfactory electronic representation. The reason for this is that a passive circuit element able to reproduce the synapse behaviour needs to remember its past dynamical history, store a continuous set of states, and be "plastic" according to the pre-synaptic and post-synaptic neuronal activity. Here we show that all this can be accomplished by a memory-resistor (memristor for short). In particular, by using simple and inexpensive off-the-shelf components we have built a memristor emulator which realizes all required synaptic properties. Most importantly, we have demonstrated experimentally the formation of associative memory in a simple neural network consisting of three electronic neurons connected by two memristor-emulator synapses. This experimental demonstration opens up new possibilities in the understanding of neural processes using memory devices, an important step forward to reproduce complex learning, adaptive and spontaneous behaviour with electronic neural networks.

Complete article available for download in multiple formats at the link displayed above.

This bears watching. Indeed, given this is mainstream research, it gives rise to the question: What have the "secured" research facilities developed and are experimenting with? Synthetic biology, artificial intelligence and robotics applications come roaring to the front...

[towhom]

Fundamental Theoretical Bias in Gravitational Wave Astrophysics and the Parameterized Post-Einsteinian Framework
arXiv
Nicolas Yunes, Frans Pretorius
[v1] Thu, 17 Sep 2009 22:16:20 GMT
Subjects: General Relativity and Quantum Cosmology (gr-qc)
PACS numbers: 04.80.Cc,04.80.Nn,04.30.-w,04.50.Kd
arxiv.org/abs/0909.3328

Abstract
We consider the concept of fundamental bias in gravitational wave astrophysics as the assumption that general relativity is the correct theory of gravity during the entire wave-generation and propagation regime. Such an assumption is valid in the weak-field, as verified by precision experiments and observations, but it need not hold in the dynamical strong-field regime where tests are lacking. Fundamental bias can cause systematic errors in the detection and parameter estimation of signals, which can lead to a mischaracterization of the universe through incorrect inferences about source event rates and populations. We propose a remedy through the introduction of the parameterized post-Einsteinian framework, which consists of the enhancement of waveform templates via the inclusion of post-Einsteinian parameters. These parameters would ostensibly be designed to interpolate between templates constructed in general relativity and well-motivated alternative theories of gravity, and also include extrapolations that follow sound theoretical principles, such as consistency with conservation laws and symmetries. As an example, we construct parameterized post-Einsteinian templates for the binary coalescence of equal-mass, non-spinning compact objects in a quasi-circular inspiral. The parametrized post-Einsteinian framework should allow matched filtered data to select a specific set of post-Einsteinian parameters without a priori assuming the validity of the former, thus either verifying general relativity or pointing to possible dynamical strong-field deviations.

Complete article available for download in multiple formats at the link displayed above.

[towhom]

Spontaneous Dimensional Reduction in Short-Distance Quantum Gravity?
arXiv
Steven Carlip
[v1] Thu, 17 Sep 2009 22:02:32 GMT
Subjects: General Relativity and Quantum Cosmology (gr-qc)
PACS: 04.60.-m,04.60.Ds,04.60.Kz,04.60.Nc,02.40.Vh
arxiv.org/abs/0909.3329

Abstract
Several lines of evidence suggest that quantum gravity at very short distances may behave effectively as a two-dimensional theory. I summarize these hints, and offer an additional argument based on the strong-coupling limit of the Wheeler-DeWitt equation. The resulting scenario suggests a novel approach to quantum gravity at the Planck scale.

Complete article available for download in multiple formats at the link displayed above.

[towhom]

Antigravitation
Why No Negative Gravitational Charges?
arXiv
Sabine Hossenfelder
[v1] Fri, 18 Sep 2009 15:00:40 GMT
Subjects: General Relativity and Quantum Cosmology (gr-qc)
PACS: 04.20.Cv, 11.30.-j, 11.30.Cp
arxiv.org/abs/0909.3456

Abstract
We discuss why there are no negative gravitational sources in General Relativity and show that it is possible to extend the classical theory such that repulsive gravitational interaction occurs.

Comments
This is the summary of a talk given at the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions in Boston, June 2009.

Complete article available for download in multiple formats at the link displayed above.