Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • 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
  • LB1 discovery as a rare event in earth history [Evolution]
    [Aug 2014]

    The original centrally defining features of “Homo floresiensis” are based on bones represented only in the single specimen LB1. Initial published values of 380-mL endocranial volume and 1.06-m stature are markedly lower than later attempts to confirm them, and facial asymmetry originally unreported, then denied, has been established by our...
    Categories: Journal Articles
  • LB1 from Flores, Indonesia, exhibits Down syndrome [Evolution]
    [Aug 2014]

    Human skeletons from Liang Bua Cave, Flores, Indonesia, are coeval with only Homo sapiens populations worldwide and no other previously known hominins. We report here for the first time to our knowledge the occipitofrontal circumference of specimen LB1. This datum makes it possible to link the 430-mL endocranial volume of...
    Categories: Journal Articles
  • How to light a cosmic candle [News Feature]
    [Aug 2014]

    Astronomers are still struggling to identify the companions that help white dwarf stars self-destruct in violent supernovae explosions. Billions of years ago, an ill-fated star not so different from our Sun began to age and balloon outward. As it grew, the star’s glow darkened to a deep, foreboding red, and...
    Categories: Journal Articles