Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Amazonian functional assembly [Ecology]
    [Apr 2014]

    Patterns of tropical forest functional diversity express processes of ecological assembly at multiple geographic scales and aid in predicting ecological responses to environmental change. Tree canopy chemistry underpins forest functional diversity, but the interactive role of phylogeny and environment in determining the chemical traits of tropical trees is poorly known....
    Categories: Journal Articles
  • Behavior thwarts thermal danger [Ecology]
    [Apr 2014]

    Physiological thermal-tolerance limits of terrestrial ectotherms often exceed local air temperatures, implying a high degree of thermal safety (an excess of warm or cold thermal tolerance). However, air temperatures can be very different from the equilibrium body temperature of an individual ectotherm. Here, we compile thermal-tolerance limits of ectotherms across...
    Categories: Journal Articles
  • Americans are ill prepared for the ACA [Economic Sciences]
    [Apr 2014]

    This paper investigates whether individuals are sufficiently informed to make reasonable choices in the health insurance exchanges established by the Affordable Care Act (ACA). We document knowledge of health reform, health insurance literacy, and expected changes in healthcare using a nationally representative survey of the US population in the 5...
    Categories: Journal Articles
  • Olive bioeconomics under climate warming [Economic Sciences]
    [Apr 2014]

    The Mediterranean Basin is a climate and biodiversity hot spot, and climate change threatens agro-ecosystems such as olive, an ancient drought-tolerant crop of considerable ecological and socioeconomic importance. Climate change will impact the interactions of olive and the obligate olive fruit fly (Bactrocera oleae), and alter the economics of olive...
    Categories: Journal Articles
  • Dynamic Archean sulfur cycle [Evolution]
    [Apr 2014]

    Many aspects of Earth’s early sulfur cycle, from the origin of mass-anomalous fractionations to the degree of biological participation, remain poorly understood—in part due to complications from postdepositional diagenetic and metamorphic processes. Using a combination of scanning high-resolution magnetic superconducting quantum interference device (SQUID) microscopy and secondary ion mass spectrometry...
    Categories: Journal Articles
  • Dangers and constructions in models of randomness [Mathematics]
    [Apr 2014]

    The certification, construction, and delineation of individual, infinite-length “random” sequences have been longstanding yet incompletely resolved problems. We address this topic via the study of normal numbers, which often have been viewed as reasonable proxies for randomness, given their limiting equidistribution of subblocks of all lengths. However, limitations arise within...
    Categories: Journal Articles
  • Lattice dynamics by ultrafast Kikuchi diffraction [Physics]
    [Apr 2014]

    In materials, the nature of the strain–stress relationship, which is fundamental to their properties, is determined by both the linear and nonlinear elastic responses. Whereas the linear response can be measured by various techniques, the nonlinear behavior is nontrivial to probe and to reveal its nature. Here, we report the...
    Categories: Journal Articles
  • Oxytocin promotes group-serving dishonesty [Psychological and Cognitive Sciences]
    [Apr 2014]

    To protect and promote the well-being of others, humans may bend the truth and behave unethically. Here we link such tendencies to oxytocin, a neuropeptide known to promote affiliation and cooperation with others. Using a simple coin-toss prediction task in which participants could dishonestly report their performance levels to benefit...
    Categories: Journal Articles
  • In This Issue [This Week in PNAS]
    [Apr 2014]

    Past climate change and marine carbon dioxide release The abrupt endings of glacial periods during the Pleistocene have led researchers to investigate the drivers of such ancient climate cycles. One hypothesis states that glacial melting may have interrupted global ocean circulation patterns in the North Atlantic, triggering a widespread release...
    Categories: Journal Articles
  • Algal phytochromes [Plant Biology]
    [Apr 2014]

    The maritime palette is blue because light of this hue alone penetrates through the upper ocean. Longer wavelengths of visible light are absorbed by water; red light is found only within the top 5–20 m of coastal ocean, and yellow and green light are lost by ∼50 and ∼70 m,...
    Categories: Journal Articles
  • Predicting species vulnerability to climate change [Ecology]
    [Apr 2014]

    Cole (1) remarked [it is] “axiomatic that the reproductive potentials of existing species are related to their requirements for survival”; this logic applies to understanding species’ capacities to respond to anthropogenic climate change. Extant species reflect the ghost of environments past: species traits such as physiological performance and tolerance are...
    Categories: Journal Articles
  • Cryptic refuges for life during glaciation [Evolution]
    [Apr 2014]

    A long-standing paradigm in ecology has been that contemporary biodiversity requires a diverse array of life to have survived through repeated Pleistocene glaciations when much of the higher latitudes on earth were covered in thick ice sheets. The notion that isolated pockets of ice-free land or “cryptic refugia” also persisted...
    Categories: Journal Articles
  • Imaging peptidoglycan with NIR fluorogenic azides [Biochemistry]
    [Apr 2014]

    Fluorescent probes designed for activation by bioorthogonal chemistry have enabled the visualization of biomolecules in living systems. Such activatable probes with near-infrared (NIR) emission would be ideal for in vivo imaging but have proven difficult to engineer. We present the development of NIR fluorogenic azide probes based on the Si-rhodamine...
    Categories: Journal Articles
  • Methanogenic burst in the end-Permian carbon cycle [Evolution]
    [Apr 2014]

    The end-Permian extinction is associated with a mysterious disruption to Earth’s carbon cycle. Here we identify causal mechanisms via three observations. First, we show that geochemical signals indicate superexponential growth of the marine inorganic carbon reservoir, coincident with the extinction and consistent with the expansion of a new microbial metabolic...
    Categories: Journal Articles
  • Supersized viruses [Science and Culture]
    [Apr 2014]

    On February 22, festival-goers at Melbourne’s dusk-to-dawn White Night celebration lined up in droves outside the State Library of Victoria for an intimate evening with herpes. And they got it, in a big way: Bobbling around on the 40-meter-diameter central dome on the ceiling of the library’s La Trobe Reading...
    Categories: Journal Articles
  • Signal or noise, a statistical perspective [Social Sciences]
    [Apr 2014]

    Best practices about the appropriate use of statistical tools in sport and clinical sciences are increasingly being fostered. For the sake of science, the interpretation of the result of an experiment is the central key, which features the interpretation of the phenomenon. Recently, an interesting article in PNAS (1) shows...
    Categories: Journal Articles
  • Jymmin, easy to implement [Social Sciences]
    [Apr 2014]

    Padulo et al. (1) comment on our recent PNAS article (2). Here, we give a response to each of their points and rebut each point. Their major concern seems to be that the musical feedback technology we used is too complex to allow for replication by other laboratories. We do...
    Categories: Journal Articles
  • MFS evolved without 3-TMS unit rearrangements [Biological Sciences]
    [Apr 2014]

    Based on alleged functional residue correspondences, a recent study proposed a model of 3-transmembrane segment (TMS) repeat unit rearrangements in Major Facilitator Superfamily (MFS) carriers (1). A rebuttal of “Evolutionary mix-and-match with MFS transporters” (1) is currently in press in the Journal of Molecular Microbiology and Biotechnology (2). In their...
    Categories: Journal Articles
  • Microclimate integral to modeled climate responses [Biological Sciences]
    [Apr 2014]

    It is becoming increasingly evident that microclimate has a large influence on the current distributions of species and their likely responses to climate change (1, 2). De Frenne et al. (3) attempt to highlight the importance of this issue, by assessing how changes in canopy cover have influenced subcanopy microclimates,...
    Categories: Journal Articles
  • Robust thermophilization estimation [Biological Sciences]
    [Apr 2014]

    We recently assessed plant community responses to macroclimate warming across European and North American temperate forests (1). To do so, we inferred the temperature preferences of understory species from distribution data by means of ecological niche, or species distribution models (SDMs). Harwood et al. (2) propose that subcanopy temperatures, instead...
    Categories: Journal Articles