Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • 2,200 y of ENSO, cyclones, and Australian floods [Earth, Atmospheric, and Planetary Sciences]
    [Apr 2015]

    Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term “direct” storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integrated analysis of meteorological...
    Categories: Journal Articles
  • Seafloor ecosystems and abrupt climate change [Earth, Atmospheric, and Planetary Sciences]
    [Apr 2015]

    Anthropogenic climate change is predicted to decrease oceanic oxygen (O2) concentrations, with potentially significant effects on marine ecosystems. Geologically recent episodes of abrupt climatic warming provide opportunities to assess the effects of changing oxygenation on marine communities. Thus far, this knowledge has been largely restricted to investigations using Foraminifera, with...
    Categories: Journal Articles
  • Behavioral contagion in mobile animal groups [Ecology]
    [Apr 2015]

    Coordination among social animals requires rapid and efficient transfer of information among individuals, which may depend crucially on the underlying structure of the communication network. Establishing the decision-making circuits and networks that give rise to individual behavior has been a central goal of neuroscience. However, the analogous problem of determining...
    Categories: Journal Articles
  • Plethora of transitions during filament breakup [Engineering]
    [Apr 2015]

    Thinning and breakup of liquid filaments are central to dripping of leaky faucets, inkjet drop formation, and raindrop fragmentation. As the filament radius decreases, curvature and capillary pressure, both inversely proportional to radius, increase and fluid is expelled with increasing velocity from the neck. As the neck radius vanishes, the...
    Categories: Journal Articles
  • Environmental tipping points and climate policies [Environmental Sciences]
    [Apr 2015]

    Most current cost−benefit analyses of climate change policies suggest an optimal global climate policy that is significantly less stringent than the level required to meet the internationally agreed 2 °C target. This is partly because the sum of estimated economic damage of climate change across various sectors, such as energy...
    Categories: Journal Articles
  • Energy allocation under ocean acidification [Environmental Sciences]
    [Apr 2015]

    Energy is required to maintain physiological homeostasis in response to environmental change. Although responses to environmental stressors frequently are assumed to involve high metabolic costs, the biochemical bases of actual energy demands are rarely quantified. We studied the impact of a near-future scenario of ocean acidification [800 µatm partial pressure...
    Categories: Journal Articles
  • The uncertain climate footprint of wetlands [Environmental Sciences]
    [Apr 2015]

    Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on...
    Categories: Journal Articles
  • Photoreduction of birnessite (MnO2) nanosheets [Environmental Sciences]
    [Apr 2015]

    The photoreductive dissolution of Mn(IV) oxide minerals in sunlit aquatic environments couples the Mn cycle to the oxidation of organic matter and fate of trace elements associated with Mn oxides, but the intrinsic rate and mechanism of mineral dissolution in the absence of organic electron donors is unknown. We investigated...
    Categories: Journal Articles
  • Mammal loss in Australia [Environmental Sciences]
    [Apr 2015]

    The highly distinctive and mostly endemic Australian land mammal fauna has suffered an extraordinary rate of extinction (>10% of the 273 endemic terrestrial species) over the last ∼200 y: in comparison, only one native land mammal from continental North America became extinct since European settlement. A further 21% of Australian...
    Categories: Journal Articles
  • The Cambrian Explosion [Evolution]
    [Apr 2015]

    The fossil record offers unique insights into the environmental and geographic partitioning of biodiversity during global diversifications. We explored biodiversity patterns during the Cambrian radiation, the most dramatic radiation in Earth history. We assessed how the overall increase in global diversity was partitioned between within-community (alpha) and between-community (beta) components...
    Categories: Journal Articles
  • Association between mRNA expression and phenotype [Genetics]
    [Apr 2015]

    High-throughput gene expression profiling has revealed substantial leaky and extraneous transcription of eukaryotic genes, challenging the perceptions that transcription is strictly regulated and that changes in transcription have phenotypic consequences. To assess the functional implications of mRNA transcription directly, we analyzed mRNA expression data derived from microarrays, RNA-sequencing, and in...
    Categories: Journal Articles
  • TOP3{alpha} and RECQ4 limit meiotic crossovers [Genetics]
    [Apr 2015]

    Meiotic crossovers (COs) have two important roles, shuffling genetic information and ensuring proper chromosome segregation. Despite their importance and a large excess of precursors (i.e., DNA double-strand breaks, DSBs), the number of COs is tightly regulated, typically one to three per chromosome pair. The mechanisms ensuring that most DSBs are...
    Categories: Journal Articles
  • Immune activation in human Ebola virus infection [Immunology and Inflammation]
    [Apr 2015]

    Four Ebola patients received care at Emory University Hospital, presenting a unique opportunity to examine the cellular immune responses during acute Ebola virus infection. We found striking activation of both B and T cells in all four patients. Plasmablast frequencies were 10–50% of B cells, compared with less than 1%...
    Categories: Journal Articles
  • Inflammatory, bladder-cancer-promoting cells [Immunology and Inflammation]
    [Apr 2015]

    Nonresolving chronic inflammation at the neoplastic site is consistently associated with promoting tumor progression and poor patient outcomes. However, many aspects behind the mechanisms that establish this tumor-promoting inflammatory microenvironment remain undefined. Using bladder cancer (BC) as a model, we found that CD14-high cancer cells express higher levels of numerous...
    Categories: Journal Articles
  • G{alpha}i1 and G{alpha}i3 regulate macrophage polarization [Immunology and Inflammation]
    [Apr 2015]

    Heterotrimeric G proteins have been implicated in Toll-like receptor 4 (TLR4) signaling in macrophages and endothelial cells. However, whether guanine nucleotide-binding protein G(i) subunit alpha-1 and alpha-3 (Gαi1/3) are required for LPS responses remains unclear, and if so, the underlying mechanisms need to be studied. In this study, we demonstrated...
    Categories: Journal Articles
  • Giant temperature response of nanobionic materials [Plant Biology]
    [Apr 2015]

    Conventional approaches to create biomaterials rely on reverse engineering of biological structures, on biomimicking, and on bioinspiration. Plant nanobionics is a recent approach to engineer new materials combining plant organelles with synthetic nanoparticles to enhance, for example, photosynthesis. Biological structures often outperform man-made materials. For example, higher plants sense temperature...
    Categories: Journal Articles
  • Family environment and cognitive ability [Psychological and Cognitive Sciences]
    [Apr 2015]

    Cognitive ability strongly aggregates in families, and prior twin and adoption studies have suggested that this is the result of both genetic and environmental factors. In this study, we used a powerful design—home-reared and adopted-away cosibling controls—to investigate the role of the rearing environment in cognitive ability. We identified, from...
    Categories: Journal Articles
  • Water conservation and food security in China [Sustainability Science]
    [Apr 2015]

    China’s economic growth is expected to continue into the next decades, accompanied by sustained urbanization and industrialization. The associated increase in demand for land, water resources, and rich foods will deepen the challenge of sustainably feeding the population and balancing agricultural and environmental policies. We combine a hydrologic model with...
    Categories: Journal Articles
  • Capturing cancer's complexity [News Feature]
    [Apr 2015]

    Some researchers believe that a tumor's heterogeneity provides crucial clues about how cancers respond to treatment. Looking down from an airplane window, it’s hard to appreciate the diversity of plants that thrive in a lush forest thousands of feet below. The shade of green might hint at a dominant species,...
    Categories: Journal Articles
  • Plausible reductions in future population growth [Biological Sciences]
    [Feb 2015]

    Bradshaw and Brook (1) conclude that a substantial slowing of global population growth is infeasible over this century short of drastic reductions in fertility, and therefore could not contribute much to lessening pressure on the environment. However, their methodology is too crude to produce credible results. Bradshaw and Brook’s (1)...
    Categories: Journal Articles