Is streamflow increasing? Trends in the coterminous United States

International audienceAn increasing trend in global streamflow has been variously attributed to climate change, land use, and a reduction in plant transpiration under higher CO2 levels. To separate these influences, we use a subset of ~1000 United States Geological Survey stream gauges primarily from small, minimally disturbed watersheds to estimate annual streamflow per unit area since 1920 on a uniform grid over the coterminous United States. We find that although streamflow has indeed increased over this period taken as a whole, this increase has not been uniform in time but concentrated in the late 1960s, when precipitation increased. Since the early 1990s, both precipitation and streamflow show nonsignificant declining trends. Multiple regression of streamflow against precipitation, temperature and CO2 suggests that higher CO2 levels may increase streamflow, presumably due to the physiological plant response to CO2, but that this positive response is more than offset by the concomitant increasing evaporation due to global warming, so that the net impact of greenhouse gas emissions has been to increase evaporation and reduce streamflow. The suppression of plant transpiration through higher CO2 levels seems to be particularly important for sustaining high streamflow in recent decades in the Great Plains, where precipitation is concentrated during the growing season

Computational neurorehabilitation: modeling plasticity and learning to predict recovery

Despite progress in using computational approaches to inform medicine and neuroscience in the last 30 years, there have been few attempts to model the mechanisms underlying sensorimotor rehabilitation. We argue that a fundamental understanding of neurologic recovery, and as a result accurate predictions at the individual level, will be facilitated by developing computational models of the salient neural processes, including plasticity and learning systems of the brain, and integrating them into a context specific to rehabilitation. Here, we therefore discuss Computational Neurorehabilitation, a newly emerging field aimed at modeling plasticity and motor learning to understand and improve movement recovery of individuals with neurologic impairment. We first explain how the emergence of robotics and wearable sensors for rehabilitation is providing data that make development and testing of such models increasingly feasible. We then review key aspects of plasticity and motor learning that such models will incorporate. We proceed by discussing how computational neurorehabilitation models relate to the current benchmark in rehabilitation modeling – regression-based, prognostic modeling. We then critically discuss the first computational neurorehabilitation models, which have primarily focused on modeling rehabilitation of the upper extremity after stroke, and show how even simple models have produced novel ideas for future investigation. Finally, we conclude with key directions for future research, anticipating that soon we will see the emergence of mechanistic models of motor recovery that are informed by clinical imaging results and driven by the actual movement content of rehabilitation therapy as well as wearable sensor-based records of daily activity

d_{x^2-y^2} Symmetry and the Pairing Mechanism

An important question is if the gap in the high temperature cuprates has d_{x^2-y^2} symmetry, what does that tell us about the underlying interaction responsible for pairing. Here we explore this by determining how three different types of electron-phonon interactions affect the d_{x^2-y^2} pairing found within an RPA treatment of the 2D Hubbard model. These results imply that interactions which become more positive as the momentum transfer increases favor d_{x^2-y^2} pairing in a nearly half-filled band.Comment: 9 pages and 2 eps figs, uses revtex with epsf, in press, PR

Experimental chronic noise is related to elevated fecal corticosteroid metabolites in lekking male greater Sage-Grouse (Centrocercus urophasianus).

There is increasing evidence that individuals in many species avoid areas exposed to chronic anthropogenic noise, but the impact of noise on those who remain in these habitats is unclear. One potential impact is chronic physiological stress, which can affect disease resistance, survival and reproductive success. Previous studies have found evidence of elevated stress-related hormones (glucocorticoids) in wildlife exposed to human activities, but the impacts of noise alone are difficult to separate from confounding factors. Here we used an experimental playback study to isolate the impacts of noise from industrial activity (natural gas drilling and road noise) on glucocorticoid levels in greater sage-grouse (Centrocercus urophasianus), a species of conservation concern. We non-invasively measured immunoreactive corticosterone metabolites from fecal samples (FCMs) of males on both noise-treated and control leks (display grounds) in two breeding seasons. We found strong support for an impact of noise playback on stress levels, with 16.7% higher mean FCM levels in samples from noise leks compared with samples from paired control leks. Taken together with results from a previous study finding declines in male lek attendance in response to noise playbacks, these results suggest that chronic noise pollution can cause greater sage-grouse to avoid otherwise suitable habitat, and can cause elevated stress levels in the birds who remain in noisy areas

Quantitative Patterns of Stylistic Influence in the Evolution of Literature

Literature is a form of expression whose temporal structure, both in content and style, provides a historical record of the evolution of culture. In this work we take on a quantitative analysis of literary style and conduct the first large-scale temporal stylometric study of literature by using the vast holdings in the Project Gutenberg Digital Library corpus. We find temporal stylistic localization among authors through the analysis of the similarity structure in feature vectors derived from content-free word usage, nonhomogeneous decay rates of stylistic influence, and an accelerating rate of decay of influence among modern authors. Within a given time period we also find evidence for stylistic coherence with a given literary topic, such that writers in different fields adopt different literary styles. This study gives quantitative support to the notion of a literary “style of a time” with a strong trend toward increasingly contemporaneous stylistic influence

Mapping and attribution of change in streamflow in the coterminous United States

An increasing trend in global streamflow has been variously attributed to global warming, land use, and a reduction in plant transpiration under higher CO<sub>2</sub> levels. To separate these influences for the coterminous United States, we use a set of over 1000 United States Geological Survey stream gauges primarily from small, minimally disturbed watersheds to estimate annual streamflow per unit area since 1920 on a uniform grid. We find that changing precipitation, which is not clearly correlated with greenhouse gas concentrations or global warming, explains most of the interannual and longer term variability in streamflow. While streamflow has indeed increased since 1920, this increase has not been steady but rather concentrated in the late 1960s, when precipitation increased. Since the early 1990s, both precipitation and streamflow show nonsignificant declining trends. Multiple regression of streamflow against precipitation, temperature and CO<sub>2</sub> suggests that higher CO<sub>2</sub> levels may increase streamflow, presumably from lower transpiration due to the physiological plant response to CO<sub>2</sub>, but that this positive response is offset by concomitant increasing evaporation due to global warming. The net impact of the opposing climate and physiological effects of CO<sub>2</sub> emissions for streamflow is close to zero for the coterminous United States taken as a whole, but shows regional variation. Streamflow at a given amount of annual precipitation has decreased in the Pacific west, where most precipitation occurs in winter. Suppression of plant transpiration through higher CO<sub>2</sub> levels may be particularly important for sustaining high streamflow in recent decades in the Great Plains, where precipitation is concentrated during the growing season

The 51^{51}Cr neutrino source and Borexino: a desirable marriage

Exposure to a $^{51}$Cr neutrino source as that used in Gallex will provide an excellent overall performance test of Borexino, which should collect about 1400 source induced events, with an initial rate of about 35 counts per day. This will be particularly important if MSW-small-angle turns out to be the solution of the solar neutrino problem. In addition, if an independent, accurate calibration is available, one will have an interesting experiment on neutrino properties: as an example, a neutrino magnetic moment of the order $5\cdot10^{-11}\mu_B$could be detected/excluded at the 90\% C.L.Comment: 7 pages, RevTeX, plus 3 postscripts figures, tarred, compresse