2009年02月28日

Moving memories

The transfer of information between the entities that do the processing and memory is crucial - and problematic - for quantum computation. In classical systems, information transfer can include a copying step, where errors can be spotted and crrected, but in quantum systems copying is fundamentally precluded.

Morton et al. demonstrate a technology that could solve the problem : the coherent storage and readout of information between electron-spin processing elements and memory elemrnts based on a nuclear spin. The system utilizes phosphourus-31 spin donors in a silicon -28 crystal.

The nuclear spin acts as a memory element that can store the full state of the electron spin for over a second, then transfer it back to the electron spin at about 90% sfficiency.


### DataBace ###
nature Vol.455 1007-1148 Issue no.7216 23 October 2008
Letter p.1085 / Solid-state quantum memory using the ^31~P nuclear spin / J J L Morton et al. (Oxford Univirsity)
* refarence

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posted by 0≠素子 at 13:37| Comment(0) | quantum information | このブログの読者になる | 更新情報をチェックする

2009年02月27日

Galaxies made simple

At farst glance a galaxy looks pretty complex : each contains bilions of stars subject to many influences including gravity, rotation and radiation.

The hierarchical theory of galaxy formation - currently fashinoable - holds that they are assembled from smaller pieces, through many mergers of cold dark matter, and that the properties of individual galaxies are determinied by six independent parameters.

Now a survey of 200 individual galaxies suggests that things are simpler than that, and that galactic structure is controlled by a single parameter. Though frustratingly, it is not yet clear which parameter that is.

This lebel of organization is at odds with hierarchical galaxy formation and the predictions of cold dark matter cosmology.


### DataBace ###
nature Vol.455 1007-1148 Issue no.7216 23 October 2008
News and Vews p.1049/ ASTROPHYSICS : How do galaxies from? / Sidney van den
Letter p.1082 / Galaxies appear simpler than expected M J Disney et al. (cardiff University)

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posted by 0≠素子 at 23:10| Comment(0) | cosmos | このブログの読者になる | 更新情報をチェックする

2009年02月26日

Apoptosis : Stabbed in the BAX

Apoptptic cell death is an intricate and highly regulated process. To isitiate apoptosis, the protein BIM binds to a hitherto unrecognized site on the BAX protain to trigger permeabilization of the outer mitochondrial membrane.

Cell death in animals mainly proceeds throuth the programmed prosess of apoptosis. In vertebrates, this usually occurs by means of pathway involving the mitochondrion, a cellular organelle (Green,D.R. Cell 121,671-674/2005).

Following damaging callular stress, the outer mitochondrial membrane becomes permeable, and factrors are released into the sytoplasm that precipitate apoptosis. the pro-apoptotic effector proteins of the BCL-2 family - BAK and BAX are responsible for permeabilizing the membrene, yet there is little structural information on the main protain-protein interactions necessary to promote this mitochondrial event. On page 1076 of this issue, Walensky, Tjandra and calleagues present an ontriguing structural analysis of the interactions between BAX and one of its activators, reavealing an unsuspected binding site.

Proteins of the BCL-2family control the integrity of the outer mitocondrial membrane and are divided into three subfamilies : anti-apoptotic proteins, pro-apoptotic effectors and BH3-only proteins (so called because, of the for evolutinarily conserved BCL-2-homology(BH)domains, only BH3 is present in these proteins).

Anti-apoptotic BCL-2 proteins prevent apoptosis by inhibiting permerbilization of the membrene, whereas the BH3-only proteins promote it.

When BAK and BAK are activated, they 'homo-oligomerize' - that is, they from complexes of either BAX-only or BAK-only molecules.

These olgomers assemble in the outer mitochondrial membrene, cousing its disruption. proteins localized between the outer and inner nenbreans, such as cytochrome ι,can then diffuse into the cytosol. Cytochrome ιand other released proteins cooperate with cytosolic factors, leading to the activation of caspase enzymes that are responsible for the features of apoptosis. But even without caspase activation, permeabilzed outer mitochondrial membrances can be sufficiently catasrophic to couse cell death.

The BH3-only protenis promote permeabilization ofthe outer mitochondrial membrane by regulating the other two subfamilies.


### DataBace ###
nature Vol.455 1007-1148 Issue no.7216 23 October 2008
News and Vews p.1047/ Apoptosis : Stabbed in the BAX / Douglas R. Green and Jerry E. Chipuk
posted by 0≠素子 at 21:05| Comment(0) | genome | このブログの読者になる | 更新情報をチェックする

Neuromotor prosthics

Brain-machine interfaces are a promising approach for treating parelysis due to spinal cord injury, by reroutting control signals from the brain to the muscles. Previous work showed that monkeys can be traibed to move robotic arms using signals from electrodes inplated in the brain.

Now it is reported that monkeys can learn move a temporariky paralysed wrist using signals artificially routed from single neurons in the brain that had not previously been associated with that movement. This may have significant implications for future design of blain-machine interfaces, which have tradidionally relied on the activity of dedecated populations of nurons.

### DataBace ###
nature Vol.456 545-674 Issue no.7222 4 December 2008
Letter p.639/Direct control of paralysed muscles by cortical neurons/ C T Moritz et al. (University of Washington)


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posted by 0≠素子 at 16:29| Comment(0) | neuron | このブログの読者になる | 更新情報をチェックする

Arctic methane revisited

A late-autum 'shoulder' is a regular fuature of the seasonal cycles of atomospheric methane at high latitudes, but the soureces of this burst of methane remain obscure. Mastepanov et al.

now report metthane flux measurements from a high Arctic setting during the onset of soilfeezing. The total emissions during this freezein period are roughly equal to the amount of methane emitted during the entire summer season. Including the observed methane burst in an atomospheric chemistry and transport model inproves agreement between the simulated seasonal cycle and atmospheric data from latitudes noeth of 60°N.

These results suggest that permafrost-associated freeze-in bursts of methane from tundra regoins may be an important previously unrecognized component of the seasonal distribution of methane emissions at high latitudes.

### DataBace ###
nature Vol.456 545-674 Issue no.7222 4 December 2008
Letters p.628 / Large tundra methane burst durring onset of freezing / M Mastepanov et al. (Lund University:Sweden)

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posted by 0≠素子 at 13:17| Comment(0) | climate | このブログの読者になる | 更新情報をチェックする

Hello

DOE and
European Commission Energy

As a Nobel prize winner of EU pointed it out in the past, over barbon reduction accomplishment is a survival crisis problem of the human who does not come true if people in the world do not make an effort.

It was the thing which gave it up from this twice three times more than once, but I had a look at data and decided to think about problem solving once again.


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posted by 0≠素子 at 06:19| Comment(0) | diary | このブログの読者になる | 更新情報をチェックする
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