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Volume 466 Issue 7307, 5 August 2010

Chemical reactions are triggered by the dynamics of valence electrons in molecular orbitals. A proof-of-principle demonstration reported in this issue shows how attosecond spectroscopy can be adapted to follow the hyperfast (subfemtosecond) motion of electron wavepackets in the valence shell - the bond-forming electrons - of krypton ions. Attosecond transient absorption spectroscopy of this type has the potential to reveal the elementary electron motions in molecules and solid-state materials that determine physical, chemical and biological properties. The cover depicts a sequence of snapshots of the oscillatory motion of a valence electron inside an atomic ion, reconstructed from attosecond pump-probe measurements. Credit: Christian Hackenberger, Ludwig Maximilians University of Munich.

Postdoc Journal

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    Life as a postdoc entails short-lived but infinitely enriching encounters.

    • Marwan Azar

Editorial

  • Editorial |

    Although China is a world leader in renewable-energy technology, it is missing the chance to deploy this equipment on a suitably grand scale at home.

  • Editorial |

    US cap-and-trade legislation has fallen victim to politics. But all is not lost.

Research Highlights

Journal Club

News

News Feature

Column

  • Column |

    More and earlier public involvement is required to steer powerful new technologies wisely, says Daniel Sarewitz.

    • Daniel Sarewitz

Correspondence

Opinion

  • Opinion |

    Telecommunications companies and oceanographers should work together to plug old and new submarine cables into research projects, says Yuzhu You. A global network could monitor climate change.

    • Yuzhu You

Books & Arts

  • Books & Arts |

    A broad account of the science of pain offers hope to patients but highlights how the culture of medicine needs to change, explains Lucy Odling-Smee.

    • Lucy Odling-Smee
  • Books & Arts |

    X-ray scans reveal Leonardo's remarkable control of glaze thickness, explains Philip Ball.

    • Philip Ball
  • Books & Arts |

    Sophisticated multimedia experiments offer platforms for learning about science through play, Aleks Krotoski finds.

    • Aleks Krotoski

News & Views

  • News & Views |

    An ingenious proposal holds that Earth's inner core is solidifying in the western hemisphere and melting in the east. The process is consequent on, and reinforces, its easterly slippage — or translation.

    • Michael I. Bergman
  • News & Views |

    In tropical rainforests, tree seedlings growing close to their parent are more likely to die. This mortality, caused by soil organisms, helps to explain the coexistence and relative abundance of species.

    • Owen T. Lewis
  • News & Views |

    Variations in several genes can increase an individual's susceptibility to complex disorders. But what tips the balance to cause the full-blown disease? For Crohn's disease, viruses could provide part of the answer.

    • Alison Simmons
  • News & Views |

    Attosecond spectroscopy has been used to track the real-time motion of electrons in a krypton ion, and to probe the entanglement between an electron removed from the atom and the ion left behind.

    • Olga Smirnova
  • News & Views |

    One of the hallmarks of cellular biochemistry is the ability to extract energy efficiently from available substrates. The malaria parasite, however, deviates from the norm, and has come up with its own solution.

    • Hagai Ginsburg
  • News & Views |

    What is the new gold standard for genome-wide association studies? As exemplified by analyses of blood lipids, it is collaboration to amass huge sample sizes and functional studies of the genes identified.

    • Alan R. Shuldiner
    • Toni I. Pollin
  • News & Views |

    The field of actinide chemistry is still young, not least because the radioactivity of these elements makes them difficult to work with. A study now reveals details of how actinide compounds might behave in water.

    • Polly L. Arnold

Article

  • Article |

    Lipid concentration in the serum is one of the most important risk factors for coronary artery disease and can be targeted for therapeutic intervention. A genome-wide association study in >100,000 individuals of European ancestry now finds 95 significantly associated loci that also affect lipid traits in non-European populations. Among associated loci are those involved in cholesterol metabolism, known targets of cholesterol-lowering drugs and those that contribute to normal variation in lipid traits and to extreme lipid phenotypes.

    • Tanya M. Teslovich
    • Kiran Musunuru
    • Sekar Kathiresan
  • Article |

    A non-coding polymorphism at a locus associated with myocardial infarction in humans creates a CCAAT/enhancer binding protein transcription factor binding site and alters the hepatic expression of the SORT1 gene. These authors show that modulating Sort1 levels in mouse liver alters levels of plasma low-density lipoprotein cholesterol and very low-density lipoprotein, potentially explaining why polymorphisms at this locus are associated with heart disease.

    • Kiran Musunuru
    • Alanna Strong
    • Daniel J. Rader
  • Article | | Open Access

    These authors report and analyse the draft genome sequence of the demosponge Amphimedon queenslandica. Sponges lie on the earliest branching lineage in the animal kingdom and thus have been important in studies of the origins of multicellularity. Comparative genomic analyses presented here provide significant insights into evolutionary origins of genes and pathways related to the hallmarks of metazoan multicellularity and to cancer biology.

    • Mansi Srivastava
    • Oleg Simakov
    • Daniel S. Rokhsar

Letter

  • Letter |

    Ground-based telescopes can in principle make high-resolution, wide-field observations when fitted with ground-layer adaptive optics (GLAO). These authors report observations of the core of the globular cluster M3 after a recent upgrade to their GLAO system. In natural seeing of 0.7″, the point spread function at 2.2-µm wavelength was sharpened to 0.3″ over a field of at least 2′. The wide-field resolution was enhanced by a factor of two to three over previous work, and extends to a wavelength of 1.2 ′m.

    • M. Hart
    • N. M. Milton
    • E. Bendek
  • Letter |

    Quantum entanglement is widely used in fundamental tests of quantum mechanics and applications such as quantum cryptography. Previous experiments have demonstrated entanglement of optical photons with trapped atoms, ions and atomic ensembles. These authors realize quantum entanglement between the polarization of a single optical photon and a solid-state qubit associated with a single electronic spin. This may provide a key building block for the solid-state realization of quantum optical networks.

    • E. Togan
    • Y. Chu
    • M. D. Lukin
  • Letter |

    Metamaterials have the counterintuitive optical property of negative refraction index. They have a wide range of possible applications, including 'invisibility cloaks' and perfect lenses, but their performance is severely limited by absorption losses. These authors have incorporated an optical gain medium within a metamaterial as a way to compensate the intrinsic loss, and show that optical pumping leads to a significantly improved negative refraction index and figure of merit within the 722–738-nm visible wavelength range.

    • Shumin Xiao
    • Vladimir P. Drachev
    • Vladimir M. Shalaev
  • Letter |

    Attosecond technology (1 as = 10−18 S) promises the tools needed to directly probe electron motion in real time. These authors report attosecond pump–probe measurements that track the movement of valence electrons in krypton ions. This first proof-of-principle demonstration uses a simple system, but the expectation is that attosecond transient absorption spectroscopy will ultimately also reveal the elementary electron motions that underlie the properties of molecules and solid-state materials.

    • Eleftherios Goulielmakis
    • Zhi-Heng Loh
    • Ferenc Krausz
  • Letter |

    These authors show that simultaneous crystallization and melting at the surface of the Earth's inner core can result in a translational mode of thermal convection within the inner core, producing the observed stratified layer of reduced seismic velocity at the base of the outer core. The dynamical model they propose also introduces an asymmetry between hemispheres that may explain the enigmatic East–West asymmetry in seismic properties of the inner core.

    • Thierry Alboussière
    • Renaud Deguen
    • Mickaël Melzani
  • Letter |

    A spectacular adaptive radiation among notosuchian crocodyliforms in the southern continents of Gondwana led to all manner of strange forms; in particular, their teeth, rather than being undifferentiated conical fangs, were often differentiated into biting and crushing types, as seen in mammals. These authors describe a new form from the Cretaceous period of Tanzania in which upper and lower dentitions were capable of occlusion, a feature otherwise known only from mammals.

    • Patrick M. O’Connor
    • Joseph J. W. Sertich
    • Jesuit Temba
  • Letter |

    One potential mechanism for maintaining biodiversity is negative feedback between a species and its specific enemies, meaning that other species can grow in its vicinity better than further individuals of the species in question. These authors show that in a tropical forest it is the soil biota that is the main cause of this feedback, and that this effect can explain the diversity.

    • Scott A. Mangan
    • Stefan A. Schnitzer
    • James D. Bever
  • Letter |

    Predicting the structure of a folded protein from first principles for any given amino-acid sequence remains a formidable computational challenge. To recruit human abilities to the task, these authors turned their Rosetta structure prediction algorithm into an online multiplayer game in which thousands of non-scientists competed and collaborated to produce new algorithms and search strategies for protein structure refinement. This shows that computationally complex problems can be effectively 'crowd-sourced' through interactive multiplayer games.

    • Seth Cooper
    • Firas Khatib
    • Foldit players

    Collection:

  • Letter |

    Network theory has become pervasive in all sectors of biology, from biochemical signalling to human societies, but identification of relevant functional communities has been impaired by many nodes belonging to several overlapping groups at once, and by hierarchical structures. These authors offer a radically different viewpoint, focusing on links rather than nodes, which allows them to demonstrate that overlapping communities and network hierarchies are two faces of the same issue.

    • Yong-Yeol Ahn
    • James P. Bagrow
    • Sune Lehmann
  • Letter |

    Chronic myelogenous leukaemia (CML) can progress from a chronic to an acute phase. These authors show in mouse models that leukaemia progression is controlled by the cell-fate regulator Musashi2, which in turn regulates Numb, Notch and p53 to block cellular differentiation. Musashi2 expression can be increased by aberrant transcription factors found in leukaemia, is observed during cancer progression in human CML patients and is associated with poorer prognosis.

    • Takahiro Ito
    • Hyog Young Kwon
    • Tannishtha Reya
  • Letter |

    The ability of retrotransposons to mobilize and insert into genes presents a challenge to a cell needing to maintain its genomic integrity. These authors have studied retrotransposition in embryonic carcinoma-derived cells. On insertion into DNA, the retrotransposon is quickly silenced, but the retrotransposon-specificity of this process implies that multiple silencing mechanisms may exist. Once cells differentiate, the ability to silence newly introduced retrotransposons is lost but previously inactivated retrotransposons remain inactive.

    • Jose L. Garcia-Perez
    • Maria Morell
    • John V. Moran
  • Letter |

    A central hub of carbon metabolism is the tricarboxylic acid (TCA) cycle, which serves to connect the processes of glycolysis, gluconeogenesis, respiration, amino acid synthesis and other biosynthetic pathways. These authors show that TCA metabolism in the human malaria parasite Plasmodium falciparum is largely disconnected from glycolysis and is organized along a fundamentally different architecture — not cyclic, but branched — from the canonical textbook pathway.

    • Kellen L. Olszewski
    • Michael W. Mather
    • Manuel Llinás
  • Letter |

    Metalloproteins are important in many biological processes, including respiration, photosynthesis and drug metabolism. Using genome sequences to predict the numbers and types of metal an organism uses is currently very challenging. These authors used a proteomics approach to identify and characterize a large number of a microorganism's metalloproteins on a genome-wide scale, and successfully separated and identified its cytoplasmic metalloproteins.

    • Aleksandar Cvetkovic
    • Angeli Lal Menon
    • Michael W. W. Adams

Careers and Recruitment

  • Careers and Recruitment |

    Marine biologists are developing an appreciation for conservation, a change that is creating new jobs. Emma Marris reports.

    • Emma Marris

Futures

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