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The price of oil is hovering at around US$100 a barrel, a psychologically powerful level that experts and analysts once discussed in purely theoretical terms. John Deutch, a chemistry professor at the Massachusetts Institute of Technology in Cambridge and former director of the US Central Intelligence Agency under President Clinton, gives his thoughts on the issue.
The next US president could lead the country into meaningful action on controlling greenhousegas emissions, but only if he, or she, can seize the moment. Jeff Tollefson reports.
For the first time, the US Congress has begun crafting comprehensive legislation to tackle global warming. Naturebrought together five experts with various backgrounds to discuss the current political climate as the United States moves towards mandatory emissions caps. A full transcript of this discussion can be downloaded here .
If you want to lead the free world, you'd better know your physics. That's the lesson from a popular undergraduate class, called 'Physics for future presidents', taught by Richard A. Muller at the University of California, Berkeley. Here he sets some typical questions. An interactive version of this quiz with extended answers is online at http://www.nature.com/news/specials/climatepolitics/index.html
50 years after the appointment of the first presidential science adviser, the White House is flooded with scientific information. Roger Pielke Jr suggests how the next administration might develop ways to use it best.
To save lives and livelihoods, natural and social scientists must work with decision-makers and politicians in the time between natural disasters as well as during them.
G-protein-coupled receptors govern many biological functions, yet little is known about the molecular basis of their activity. The structure of a prominent example of these receptors is now revealed.
The Moon could have been derived from a well-mixed disk of rock vapour that was produced after the early Earth collided with another planet. This persuasive idea offers a fresh perspective on the history of both bodies.
“Do not speak — unless it improves on silence” is generally wise advice, and is even vital for a subset of essential genes. New studies describe how, when appropriate, the silence of these genes is broken.
The amount of river-borne carbon that is buried upon reaching the sea affects Earth's atmospheric composition. A study of rivers draining the Himalaya shows that carbon burial may occur more efficiently than was thought.
To set the scene for its replication, the bacterium Legionella pneumophila exploits its host cells' Rab1 protein. This pathogen seems to use minimal resources to mimic the normal cycle of Rab1 activity.
The most sensitive phase-measuring instrument yet uses quantum trickery and a scaled-down version of the notorious Schrödinger's cat. It means that more sensitive devices for metrology and imaging could be on the way.
Legionella pneumophila directs maturation of its intracellular host compartment through effector secretion through the type 4 secretion system Dot/Icm. In addition to its GEF activity, L. pneumophila DrrA is shown to possess GDF for Rab1 GTPase, an acitivty which has until now only been described for one eukaryotic protein.
One of two papers that demonstrates the importance of the lipid-exposed 'paddle' motif in voltage-dependant ion channels by showing that paddle function can be faithfully conserved when transplanted into distantly-related channels. The work also underscores the mobility of this motif within the membrane.
The second of two papers about the mechanism of voltage-activation of ion channels describes a high resolution structure of a modified Kv1.2 potassium channel surrounded by a bilayer-like arrangement of lipids. The work reveals how critical positive charges in the paddle are stabilized by both lipid and protein interactions and suggests a way in which the paddle may move in response to voltage to open the channel pore.
High resolution structural information for G protein-coupled receptors has so far been limited to rhodopsin; here a crystal structure of the β2AR adrenaline receptor is presented.
Supernova 2006gy in the galaxy NGC 1260 is the most luminous one recorded. Its progenitor might have been a very massive star, but that is incompatible with hydrogen in the spectrum of the supernova. Instead, it might have arisen from the merger of two massive stars. However, the collision frequency of massive stars in a dense and young cluster is sufficient to provide a reasonable chance that SN 2006gy resulted from such a bombardment.
This paper reports that the brightest supernovae arise from collisions between shells of matter ejected by massive stars. An electron-positron 'pair instability' leads to explosive burning that ejects many solar masses of material. When the next explosion occurs, several solar masses of material are again ejected, which collide with the earlier ejecta, radiating 1050 erg of light.
At the fundamental level, measurement precision is limited by the number of quantum resources that are used. Standard measurement schemes lead to a phase uncertainty that scales with this number. In principle, it should be possible to achieve a precision limited only by the Heisenberg uncertainty principle. Here, an approach using unentangled single-photon states enables the achievement of Heisenberg-limited phase estimation. This represents a drastic reduction in the complexity of achieving quantum-enhanced measurement precision.
A new approach for achieving strong coupling between optical emitters and their environment is demonstrated by combining techniques and ideas from plasmon and quantum optics. The emitter is a semiconductor quantum dot that is placed near a silver nanowire. Light from the quantum dot can couple directly to guided surface plasmons inside the metallic nanowire, which causes the ends of the nanowire to light up. Spectroscopy measurements indicate that this is the result of single plasmons scattering from the wire end.
A comprehensive organic carbon budget for the Himalayan erosional system is presented, and finds that organic carbon export is controlled by sediment properties and that oxidative loss is negligible during transport and deposition to the ocean. The results indicate that 70 to 85 per cent of the organic carbon is recent organic matter captured during transport, which serves as a net sink for atmospheric carbon dioxide.
Several bacterial pathogens including Pseudomonas aeruginosa use cell-to-cell signalling to regulate virulence factor expression. The cost of communication is believed to allow for cheaters and this paper provides experimental evidence that this is the case, signal and signal-receptor mutants display a fitness advantage. But this advantage decreases with an increase in relatedness of the competing strains, a phenomenon known as kin selection.
The SMRT transcriptional co-repressor is shown to have a crucial role in forebrain development and in maintaining neural stem cells, and it represses expression of a histone H3 trimethyl K27 demethylase, which can activate components of the neurogenic programme.
Apoptotic cells must be removed by phagocytes to avoid local inflammation. They expose phosphatidylserine, which is normally restricted to the inner leaflet of the plasma membrane, on their surface, acting as an 'eat-me' signal. This paper shows that the BAI1 protein is an upstream receptor for phosphatidylserine in mammalian macrophages
Apoptotic cells expose phosphatidylserine as an 'eat-me' signal for macrophages. This paper shows that the receptors Tim4 and Tim1 are implicated in phagocyte recognition of phosphatidylserine.
SUV39H1 is the major methyltransferase responsible for tri-methylation of histone H3 at lysine 9 in heterochromatin. The histone deacetylase SIRT1 is shown to target the SUV39H1 enzyme and contribute to elevated levels of SUV39H1 activity and H3K9me3 in heterochromatin.
RNA polymerase II (Pol II) uses a DNA template to direct RNA synthesis during transcription, but there is also emerging evidence that it can use RNA as a template. In this paper the RNA-dependent RNA polymerase activity of Pol II is biochemically and structurally characterized.
