Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • MoS2/WSe2 van der Waals heterostructures [Applied Physical Sciences]
    [Apr 2014]

    Semiconductor heterostructures are the fundamental platform for many important device applications such as lasers, light-emitting diodes, solar cells, and high-electron-mobility transistors. Analogous to traditional heterostructures, layered transition metal dichalcogenide heterostructures can be designed and built by assembling individual single layers into functional multilayer structures, but in principle with atomically sharp...
    Categories: Journal Articles
  • Inhibition of tyrosine-phosphorylated STAT3 [Biochemistry]
    [Apr 2014]

    Signal transducer and activator of transcription 3 (STAT3) is a multifunctional protein that participates in signaling pathways initiated by various growth factors and cytokines. It exists in multiple forms including those phosphorylated on Tyr705 (pYSTAT3) or Ser727 (pSSTAT3) as well as the unphosphorylated protein (USTAT3). In addition to the canonical...
    Categories: Journal Articles
  • Molecular basis of NpmA action on the 30S subunit [Biochemistry]
    [Apr 2014]

    Aminoglycosides are potent, broad spectrum, ribosome-targeting antibacterials whose clinical efficacy is seriously threatened by multiple resistance mechanisms. Here, we report the structural basis for 30S recognition by the novel plasmid-mediated aminoglycoside-resistance rRNA methyltransferase A (NpmA). These studies are supported by biochemical and functional assays that define the molecular features necessary...
    Categories: Journal Articles
  • Molecular basis of [2Fe-2S] cluster transfer [Chemistry]
    [Apr 2014]

    Monothiol glutaredoxins play a crucial role in iron–sulfur (Fe/S) protein biogenesis. Essentially all of them can coordinate a [2Fe-2S] cluster and have been proposed to mediate the transfer of [2Fe-2S] clusters from scaffold proteins to target apo proteins, possibly by acting as cluster transfer proteins. The molecular basis of [2Fe-2S]...
    Categories: Journal Articles
  • Mn2O3 transforms to Mn3O4 via water chemisorption [Earth, Atmospheric, and Planetary Sciences]
    [Apr 2014]

    Chemisorption of water onto anhydrous nanophase manganese oxide surfaces promotes rapidly reversible redox phase changes as confirmed by calorimetry, X-ray diffraction, and titration for manganese average oxidation state. Surface reduction of bixbyite (Mn2O3) to hausmannite (Mn3O4) occurs in nanoparticles under conditions where no such reactions are seen or expected on...
    Categories: Journal Articles
  • Younger Dryas warming and deglaciation in Scotland [Earth, Atmospheric, and Planetary Sciences]
    [Apr 2014]

    The Younger Dryas Stadial (YDS; ∼12,900–11,600 y ago) in the Northern Hemisphere is classically defined by abrupt cooling and renewed glaciation during the last glacial–interglacial transition. Although this event involved a global reorganization of atmospheric and oceanic circulation [Denton GH, Alley RB, Comer GC, Broecker WS (2005) Quat Sci Rev...
    Categories: Journal Articles
  • Arctic and Antarctic ozone depletion [Earth, Atmospheric, and Planetary Sciences]
    [Apr 2014]

    Antarctic ozone depletion is associated with enhanced chlorine from anthropogenic chlorofluorocarbons and heterogeneous chemistry under cold conditions. The deep Antarctic “hole” contrasts with the generally weaker depletions observed in the warmer Arctic. An unusually cold Arctic stratospheric season occurred in 2011, raising the question of how the Arctic ozone chemistry...
    Categories: Journal Articles
  • Reconfigurable acoustic metamaterials [Engineering]
    [Apr 2014]

    Photonic and phononic crystals are metamaterials with repeating unit cells that result in internal resonances leading to a range of wave guiding and filtering properties and are opening up new applications such as hyperlenses and superabsorbers. Here we show the first, to our knowledge, 3D colloidal phononic crystal that is...
    Categories: Journal Articles
  • Size effects on strength [Engineering]
    [Apr 2014]

    The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field...
    Categories: Journal Articles
  • Methane emission from a shale gas field [Environmental Sciences]
    [Apr 2014]

    The identification and quantification of methane emissions from natural gas production has become increasingly important owing to the increase in the natural gas component of the energy sector. An instrumented aircraft platform was used to identify large sources of methane and quantify emission rates in southwestern PA in June 2012....
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  • Modeling domestication history [Evolution]
    [Apr 2014]

    The domestication of plants and animals marks one of the most significant transitions in human, and indeed global, history. Traditionally, study of the domestication process was the exclusive domain of archaeologists and agricultural scientists; today it is an increasingly multidisciplinary enterprise that has come to involve the skills of evolutionary...
    Categories: Journal Articles
  • Domestication beyond the single gene [Evolution]
    [Apr 2014]

    Domestication is a multifaceted evolutionary process, involving changes in individual genes, genetic interactions, and emergent phenotypes. There has been extensive discussion of the phenotypic characteristics of plant domestication, and recent research has started to identify the specific genes and mutational mechanisms that control domestication traits. However, there is an apparent...
    Categories: Journal Articles
  • (100 x 100)-dimensional entangled quantum system [Physics]
    [Apr 2014]

    Entangled quantum systems have properties that have fundamentally overthrown the classical worldview. Increasing the complexity of entangled states by expanding their dimensionality allows the implementation of novel fundamental tests of nature, and moreover also enables genuinely new protocols for quantum information processing. Here we present the creation of a (100...
    Categories: Journal Articles
  • Convergent evolution in plant domestication [Anthropology]
    [Apr 2014]

    Recent increases in archaeobotanical evidence offer insights into the processes of plant domestication and agricultural origins, which evolved in parallel in several world regions. Many different crop species underwent convergent evolution and acquired domestication syndrome traits. For a growing number of seed crop species, these traits can be quantified by...
    Categories: Journal Articles
  • Glucose and intimate partner violence [Psychological and Cognitive Sciences]
    [Apr 2014]

    Intimate partner violence affects millions of people globally. One possible contributing factor is poor self-control. Self-control requires energy, part of which is provided by glucose. For 21 days, glucose levels were measured in 107 married couples. To measure aggressive impulses, each evening participants stuck between 0 and 51 pins into...
    Categories: Journal Articles
  • Optimal provision of ecosystem services [Sustainability Science]
    [Apr 2014]

    Many ecosystem services are public goods whose provision depends on the spatial pattern of land use. The pattern of land use is often determined by the decisions of multiple private landowners. Increasing the provision of ecosystem services, though beneficial for society as a whole, may be costly to private landowners....
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  • The forgotten half of scientific thinking [Opinion]
    [Apr 2014]

    Although thinking is the core business of scientists, we rarely ponder how it thrives best; this is ironic, as there is abundant scientific insight to draw upon. For example, it is now known that thinking has two complementary modes: roughly, association versus reasoning (1). We systematically underestimate the role of...
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  • Freeze-mediated expansion of mangroves [Biological Sciences]
    [Apr 2014]

    Giri and Long (1) agree with our conclusion (2) that the expansion of mangroves from 1984 to 2011 near their range limit on the Atlantic coast of Florida is a threshold response to fewer days below −4 °C. However, they suggest that our conclusions would have been “substantially different” had...
    Categories: Journal Articles
  • Strong evidence for protein epistasis [Biological Sciences]
    [Apr 2014]

    A recent paper by Ashenberg et al. (1) reports protein stability measurements and computational simulations that they claim contradict the results of our previous paper describing a “Stokes shift” in protein evolution (2). They make strong assertions that coevolutionary interactions among amino acids due to effects on stability do not...
    Categories: Journal Articles
  • CD133 and kidney repair [Biological Sciences]
    [Apr 2014]

    Kusaba et al. provide additional evidence using genetic lineage analysis that epithelial cell dedifferentiation is responsible for repair of proximal tubules after injury in mouse (1). These data challenge the hypothesis of the implication of scattered stem cells in such a process or highlight a potential distinction between rodent and...
    Categories: Journal Articles