Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Oxysterols are agonist ligands of ROR{gamma}t [Immunology and Inflammation]
    [Aug 2014]

    The RAR-related orphan receptor gamma t (RORγt) is a nuclear receptor required for generating IL-17–producing CD4+ Th17 T cells, which are essential in host defense and may play key pathogenic roles in autoimmune diseases. Oxysterols elicit profound effects on immune and inflammatory responses as well as on cholesterol and lipid...
    Categories: Journal Articles
  • Circulating miRNA in patients with hepatotoxicity [Medical Sciences]
    [Aug 2014]

    We have identified, by quantitative real-time PCR, hundreds of miRNAs that are dramatically elevated in the plasma or serum of acetaminophen (APAP) overdose patients. Most of these circulating microRNAs decrease toward normal levels during treatment with N-acetyl cysteine (NAC). We identified a set of 11 miRNAs whose profiles and dynamics...
    Categories: Journal Articles
  • Multimonth small molecule release [Medical Sciences]
    [Aug 2014]

    Long-term, localized delivery of small molecules from a biodegradable thin film is challenging owing to their low molecular weight and poor charge density. Accomplishing highly extended controlled release can facilitate high therapeutic levels in specific regions of the body while significantly reducing the toxicity to vital organs typically caused by...
    Categories: Journal Articles
  • Artificial selection for structural colors [Physics]
    [Aug 2014]

    Brilliant animal colors often are produced from light interacting with intricate nano-morphologies present in biological materials such as butterfly wing scales. Surveys across widely divergent butterfly species have identified multiple mechanisms of structural color production; however, little is known about how these colors evolved. Here, we examine how closely related...
    Categories: Journal Articles
  • Nonliteral understanding of number words [Psychological and Cognitive Sciences]
    [Aug 2014]

    One of the most puzzling and important facts about communication is that people do not always mean what they say; speakers often use imprecise, exaggerated, or otherwise literally false descriptions to communicate experiences and attitudes. Here, we focus on the nonliteral interpretation of number words, in particular hyperbole (interpreting unlikely...
    Categories: Journal Articles
  • Environmental costs of animal-based categories [Sustainability Science]
    [Aug 2014]

    Livestock production impacts air and water quality, ocean health, and greenhouse gas (GHG) emissions on regional to global scales and it is the largest use of land globally. Quantifying the environmental impacts of the various livestock categories, mostly arising from feed production, is thus a grand challenge of sustainability science....
    Categories: Journal Articles
  • In This Issue [This Week in PNAS]
    [Aug 2014]

    Printed diode connects Internet-of-things with mobile networks All-printed e-tag activated by placing a call from a mobile phone. Image courtesy of Peter Modin (Linköping University, Linköping, Sweden) and Acreo Swedish ICT. In the future, physical objects may interact with humans through a proposed Internet-like network known as the Internet-of-things (IoT)....
    Categories: Journal Articles
  • Profile of Alexander D. Johnson [Profiles]
    [Aug 2014]

    Discussing the yeast Candida albicans, biochemist Alexander Johnson describes a resident of the human gut that can turn into a fatal pathogen in the immunocompromised. Johnson, a professor of microbiology and immunology at the University of California, San Francisco, appreciates the genetic intricacies of this eukaryote that changed his views...
    Categories: Journal Articles
  • Neuroadaptive changes in marijuana abusers [Neuroscience]
    [Aug 2014]

    The current watershed in legal status and rising use of marijuana can be traced to a California ballot initiative (Prop. 215, its legal successor SB420), that enabled widespread access to smokeable or edible forms of marijuana for self-reported medical conditions. Circumventing the Food and Drug Administration (FDA) drug approval process,...
    Categories: Journal Articles
  • Ultrafast printed diode rectifiers [Applied Physical Sciences]
    [Aug 2014]

    Printing electronics is a revolutionary approach for fabricating mechanically flexible, low-cost, lightweight, roll-to-roll manufacturable, and large-area optoelectronic devices (1–3). This disruptive technology relies on unconventional electronic materials (semiconductors, dielectrics, conductors, passives) that can be formulated into inks and then printed into specific patterns using processes borrowed from the graphic arts...
    Categories: Journal Articles
  • PCB dechlorinases revealed at last [Environmental Sciences]
    [Aug 2014]

    It has taken three decades from the first report of microbial polychlorinated biphenyl (PCB) dechlorination to identify even one of the enzymes responsible. By combining conventional techniques with their own ingenuity, the latest technologies, and a bit of luck, Wang et al., in PNAS, have identified not one, but three...
    Categories: Journal Articles
  • Urination time does not change with body size [Applied Biological Sciences]
    [Aug 2014]

    Many urological studies rely on models of animals, such as rats and pigs, but their relation to the human urinary system is poorly understood. Here, we elucidate the hydrodynamics of urination across five orders of magnitude in body mass. Using high-speed videography and flow-rate measurement obtained at Zoo Atlanta, we...
    Categories: Journal Articles
  • Singlet-triplet qubit with micromagnet [Applied Physical Sciences]
    [Aug 2014]

    The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double-quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micromagnet, the magnetic field difference...
    Categories: Journal Articles
  • All-printed diode operating at 1.6 GHz [Applied Physical Sciences]
    [Aug 2014]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile...
    Categories: Journal Articles
  • Vibrations and elasticity in disordered solids [Applied Physical Sciences]
    [Aug 2014]

    In the recent years, much attention has been devoted to the inhomogeneous nature of the mechanical response at the nanoscale in disordered solids. Clearly, the elastic heterogeneities that have been characterized in this context are expected to strongly affect the nature of the sound waves which, in contrast to the...
    Categories: Journal Articles
  • Thr4 of the yeast CTD mediates Htz1 dynamics [Biochemistry]
    [Aug 2014]

    The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (RNAP II) consists of repeated YSPTSPS heptapeptides and connects transcription with cotranscriptional events. Threonine-4 (Thr4) of the CTD repeats has been shown to function in histone mRNA 3′-end processing in chicken cells and in transcriptional elongation in human...
    Categories: Journal Articles
  • Scalable NMR spectroscopy with semiconductor chips [Chemistry]
    [Aug 2014]

    State-of-the-art NMR spectrometers using superconducting magnets have enabled, with their ultrafine spectral resolution, the determination of the structure of large molecules such as proteins, which is one of the most profound applications of modern NMR spectroscopy. Many chemical and biotechnological applications, however, involve only small-to-medium size molecules, for which the...
    Categories: Journal Articles
  • Testing for ontological errors [Earth, Atmospheric, and Planetary Sciences]
    [Aug 2014]

    Probabilistic forecasting models describe the aleatory variability of natural systems as well as our epistemic uncertainty about how the systems work. Testing a model against observations exposes ontological errors in the representation of a system and its uncertainties. We clarify several conceptual issues regarding the testing of probabilistic forecasting models...
    Categories: Journal Articles
  • Nonvolcanic sulfur-isotope anomaly in atmosphere [Earth, Atmospheric, and Planetary Sciences]
    [Aug 2014]

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ33S = +1.66‰ and Δ36S =...
    Categories: Journal Articles
  • Universal mobile electrochemical detector [Engineering]
    [Aug 2014]

    This paper describes an inexpensive, handheld device that couples the most common forms of electrochemical analysis directly to “the cloud” using any mobile phone, for use in resource-limited settings. The device is designed to operate with a wide range of electrode formats, performs on-board mixing of samples by vibration, and...
    Categories: Journal Articles