Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Discontinuation of the Prearranged Editor process [Editorials]
    [Oct 2014]

    Although the largest number of submissions to PNAS are through the Direct Submission route, there continues to linger a general perception that to publish a paper in PNAS, an author requires sponsorship of an NAS member. In July 2010, the member Communicated route was eliminated, but to ensure and promote...
    Categories: Journal Articles
  • Stephen F. Heinemann: A true original [Retrospectives]
    [Oct 2014]

    Steve Heinemann, one of the founders of 21st century neuroscience, died on August 6, 2014. To those who had the honor to know him, “Stevie” was a man of personal and professional generosity, contagious energy, scientific integrity, and genuine enthusiasm. His death is a profound loss for all. Stephen F....
    Categories: Journal Articles
  • Frequencies mark the direction of communication [Neuroscience]
    [Oct 2014]

    The capacity of the nervous system to perceive sensory information, form new memories, navigate through space, and make decisions relies on complex communication within and between brain areas. Anatomical studies have identified the routes by which information flows within the six layers of the neocortex and between hierarchically organized cortical...
    Categories: Journal Articles
  • Unwiring the transcriptional heat circuit [Developmental Biology]
    [Oct 2014]

    Mature adipocytes are postmitotic (1), and therefore development of adipocytes requires the proliferation and differentiation of progenitor cells into mature adipocytes. The identity of adipose precursor cells and the molecular mechanisms that control their proliferation and differentiation are only partially understood. Brown adipose tissue (BAT) is specialized for energy expenditure...
    Categories: Journal Articles
  • HCN channel gating [Physiology]
    [Oct 2014]

    Proteins possess the uncanny ability to telegraph signals over long distances. The presence of a ligand, snugly bound to a site on one end of a molecule, can be “felt” by an effector domain several nanometers away. Determining precisely how this task is accomplished is a major challenge for structural...
    Categories: Journal Articles
  • Chiral nanopore arrays [Applied Physical Sciences]
    [Oct 2014]

    A series of simple hierarchical self-assembly steps achieve self-organization from the centimeter to the subnanometer-length scales in the form of square-centimeter arrays of linear nanopores, each one having a single chiral helical nanofilament of large internal surface area and interfacial interactions based on chiral crystalline molecular arrangements.
    Categories: Journal Articles
  • Vivid, full-color aluminum plasmonic pixels [Applied Physical Sciences]
    [Oct 2014]

    Aluminum is abundant, low in cost, compatible with complementary metal-oxide semiconductor manufacturing methods, and capable of supporting tunable plasmon resonance structures that span the entire visible spectrum. However, the use of Al for color displays has been limited by its intrinsically broad spectral features. Here we show that vivid, highly...
    Categories: Journal Articles
  • Telomeric G-quadruplexes captured in {alpha}-hemolysin [Biochemistry]
    [Oct 2014]

    Human telomeric DNA consists of tandem repeats of the sequence 5′-TTAGGG-3′ that can fold into various G-quadruplexes, including the hybrid, basket, and propeller folds. In this report, we demonstrate use of the α-hemolysin ion channel to analyze these subtle topological changes at a nanometer scale by providing structure-dependent electrical signatures...
    Categories: Journal Articles
  • Dynamical traps hinder energy flow [Chemistry]
    [Oct 2014]

    The phenomenon of intramolecular vibrational energy redistribution (IVR) is at the heart of chemical reaction dynamics. Statistical rate theories, assuming instantaneous IVR, predict exponential decay of the population with the properties of the transition state essentially determining the mechanism. However, there is growing evidence that IVR competes with the reaction...
    Categories: Journal Articles
  • Mechanochemical actuator of epithelial contraction [Developmental Biology]
    [Oct 2014]

    Spatiotemporal regulation of cell contractility coordinates cell shape change to construct tissue architecture and ultimately directs the morphology and function of the organism. Here we show that contractility responses to spatially and temporally controlled chemical stimuli depend much more strongly on intercellular mechanical connections than on biochemical cues in both...
    Categories: Journal Articles
  • Atmospheric controls on NE Pacific temperature [Earth, Atmospheric, and Planetary Sciences]
    [Oct 2014]

    Over the last century, northeast Pacific coastal sea surface temperatures (SSTs) and land-based surface air temperatures (SATs) display multidecadal variations associated with the Pacific Decadal Oscillation, in addition to a warming trend of ∼0.5–1 °C. Using independent records of sea-level pressure (SLP), SST, and SAT, this study investigates northeast (NE)...
    Categories: Journal Articles
  • Alpha and gamma propagate in opposite directions [Neuroscience]
    [Oct 2014]

    Cognitive functions rely on the coordinated activity of neurons in many brain regions, but the interactions between cortical areas are not yet well understood. Here we investigated whether low-frequency (α) and high-frequency (γ) oscillations characterize different directions of information flow in monkey visual cortex. We recorded from all layers of...
    Categories: Journal Articles
  • Emergence of LR order in sheets of magnetic dimers [Physics]
    [Oct 2014]

    Quantum spins placed on the corners of a square lattice can dimerize and form singlets, which then can be transformed into a magnetic state as the interactions between dimers increase beyond threshold. This is a strictly 2D transition in theory, but real-world materials often need the third dimension to stabilize...
    Categories: Journal Articles
  • Quantum spin Hall state on Si surface [Physics]
    [Oct 2014]

    Formation of topological quantum phase on a conventional semiconductor surface is of both scientific and technological interest. Here, we demonstrate epitaxial growth of 2D topological insulator, i.e., quantum spin Hall state, on Si(111) surface with a large energy gap, based on first-principles calculations. We show that the Si(111) surface functionalized...
    Categories: Journal Articles
  • Scaling description of the yielding transition [Physics]
    [Oct 2014]

    Yield stress materials flow if a sufficiently large shear stress is applied. Although such materials are ubiquitous and relevant for industry, there is no accepted microscopic description of how they yield, even in the simplest situations in which temperature is negligible and in which flow inhomogeneities such as shear bands...
    Categories: Journal Articles
  • Preferring sex dimorphic faces may be novel [Psychological and Cognitive Sciences]
    [Oct 2014]

    A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data...
    Categories: Journal Articles
  • Stewardship of the human microbiome [Opinion]
    [Oct 2014]

    Many studies have shown how the human gut microbiome can be altered by diet, antibiotics, and other factors. All of these factors can contribute to dysbiosis, where the services typically provided by symbiotic microflora are disrupted because of shifts in function or diversity. Just as humans have impacted many large...
    Categories: Journal Articles
  • Furan fatty acids [Microbiology]
    [Aug 2014]

    Fatty acids play important functional and protective roles in living systems. This paper reports on the synthesis of a previously unidentified 19 carbon furan-containing fatty acid, 10,13-epoxy-11-methyl-octadecadienoate (9-(3-methyl-5-pentylfuran-2-yl)nonanoic acid) (19Fu-FA), in phospholipids from Rhodobacter sphaeroides. We show that 19Fu-FA accumulation is increased in cells containing mutations that increase the transcriptional...
    Categories: Journal Articles
  • Blocking TGF-{beta} signaling restricts medulloblastoma [Neuroscience]
    [Aug 2014]

    Cancer cell secretion of TGF-β is a potent mechanism for immune evasion. However, little is known about how central nervous system tumors guard against immune eradication. We sought to determine the impact of T-cell TGF-β signaling blockade on progression of medulloblastoma (MB), the most common pediatric brain tumor. Genetic abrogation...
    Categories: Journal Articles
  • Curvature-processing network [Neuroscience]
    [Aug 2014]

    Our visual environment abounds with curved features. Thus, the goal of understanding visual processing should include the processing of curved features. Using functional magnetic resonance imaging in behaving monkeys, we demonstrated a network of cortical areas selective for the processing of curved features. This network includes three distinct hierarchically organized...
    Categories: Journal Articles