Knowledge of Bat Rabies and Human Exposure Among United States Cavers

We surveyed cavers who attended the National Speleological Society convention in June 2000. Fifteen percent of respondents did not consider a bat bite a risk for acquiring rabies; only 20% had received preexposure prophylaxis against the disease. An under-appreciation of the risk for rabies from bat bites may explain the preponderance of human rabies viruses caused by variant strains associated with bats in the United States

Incidence and public health burden of sunburn among beachgoers in the United States.

The beach environment creates many barriers to effective sun protection, putting beachgoers at risk for sunburn, a well-established risk factor for skin cancer. Our objective was to estimate incidence of sunburn among beachgoers and evaluate the relationship between sunburn incidence and sun-protective behaviors. A secondary analysis, of prospective cohorts at 12 locations within the U.S. from 2003 to 2009 (n = 75,614), were pooled to evaluate sunburn incidence 10-12 days after the beach visit. Behavioral and environmental conditions were cross-tabulated with sunburn incidence. Multivariable logistic regression was used to estimate the association between new sunburn and sun-protective behaviors. Overall, 13.1% of beachgoers reported sunburn. Those aged 13-18 years (16.5%), whites (16.0%), and those at beach locations along the Eastern Seaboard (16.1%), had the highest incidence of sunburn. For those spending ≥5 h in the sun, the use of multiple types of sun protection reduced odds of sunburn by 55% relative to those who used no sun protection (Odds Ratio = 0.45 (95% Confidence Interval:0.27-0.77)) after adjusting for skin type, age, and race. Acute health effects of sunburn tend to be mild and self-limiting, but potential long-term health consequences are more serious and costly. Efforts to encourage and support proper sun-protective behaviors, and increase access to shade, protective clothing, and sunscreen, can help prevent sunburn and reduce skin cancer risk among beachgoers

Identifying evolving priorities in national river governance from Parliamentary Questions

Rivers and their surrounding land provide resources and services that result in trade-offs requiring legislative and institutional interventions, for which the perspectives of law-policymakers and their societal values and political expediencies play a major role in decision-making. This study critically evaluates the evolving land–river governance in large democratically elected governments with complex developmental priorities and how law-policymakers’ recognition of emerging issues of river management influences common pool environmental resources governance. We selected an emerging economy – India – and analysed Parliamentary Questions (PQs) between 1999 and 2020 using a mixed method approach. Conflicting priorities over economic development, pollution management, socio-cultural values and inter-state–centre issues shape the evolving priorities of land–river governance. A declining focus on large-scale dams coupled with increasing attention on inter-basin water transfers, river conservation and pollution abatement, demonstrates an evolution away from the earlier narrow view of rivers for irrigation and hydropower. Our analysis demonstrates how the priorities of law-policymakers and political expedience play a critical role in river governance and thereby provide important insights into common pool environmental resources governance for sustainable development while also identifying important knowledge gaps and suggesting scopes for interdisciplinary studies

Quantification of sand bar morphology : a video technique based on wave dissipation

A technique is presented to remotely measure the scales and morphology of natural sandbars based on the preferential dissipation of wind waves and swell over the crests of the bar. Photographic or video images are recorded and statistical uncertainties associated with incident wave height modulations removed by averaging (time exposures). Ground truth testing of the technique was carried out as part of the SUPERDUCK experiment in October 1986. The time exposures generally provided a good mapping of underlying morphology, allowing detection of the bar and determination of cross-shore and longshore length scales. However, during high waves, persistent surface foam obscures the relationship of image intensity to local dissipation (modeled theoretically by dissipation of a random wave field), and an enhancement technique of image differencing must be done to remove the bias. Errors in the estimate of bar crest distance from the shoreline are generally less than 35%, but this value depends on the geometry of the particular bar. Logistic simplicity and quantitative capabilities make this technique very attractive

Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates

We report on the orbital architectures of Kepler systems having multiple planet candidates identified in the analysis of data from the first six quarters of Kepler data and reported by Batalha et al. (2013). These data show 899 transiting planet candidates in 365 multiple-planet systems and provide a powerful means to study the statistical properties of planetary systems. Using a generic mass-radius relationship, we find that only two pairs of planets in these candidate systems (out of 761 pairs total) appear to be on Hill-unstable orbits, indicating ~96% of the candidate planetary systems are correctly interpreted as true systems. We find that planet pairs show little statistical preference to be near mean-motion resonances. We identify an asymmetry in the distribution of period ratios near first-order resonances (e.g., 2:1, 3:2), with an excess of planet pairs lying wide of resonance and relatively few lying narrow of resonance. Finally, based upon the transit duration ratios of adjacent planets in each system, we find that the interior planet tends to have a smaller transit impact parameter than the exterior planet does. This finding suggests that the mode of the mutual inclinations of planetary orbital planes is in the range 1.0-2.2 degrees, for the packed systems of small planets probed by these observations.Comment: Accepted to Ap

Catchment and climatic influences on spatio-temporal variations in suspended sediment transport dynamics in rivers

Suspended sediment concentration (SSC) is an important attribute for water resources management. However, the interactions between climate and catchment characteristics that control the temporal variability of SSC in rivers are not fully resolved. The study aim is to evaluate how these variables influence spatial and seasonal variations in SSC dynamics at a continental scale. Daily SSC (mg/l) and site attribute data from 120 sites (USA) with minimum 10 years of record (1971–2000) were analysed. New indicators of SSC dynamics (magnitude and frequency) were developed and applied annually and seasonally. Geographically weighted regression (GWR) models were created for each ordinary least squares (OLS) regression model, and GWR coefficients were analysed by ecoregion. Land cover, rainfall and erosivity, baseflow index and soil texture were the most common variables in the OLS models. GWR coefficients displayed significant variation across the continent. Agricultural cover was positively associated with low frequency SSC events, while urban and forest cover predicted higher frequency events, except in the desert areas. PPT30 was generally a negative predictor for SSC magnitude, except the marine west coasts forests. These findings on catchment and climate controls on SSC will support future predictive models of SS transport dynamics

An optical technique for the measurement of longshore currents

We present an optical method (optical current meter) to measure the longshore component of nearshore surface currents by measuring the alongshore drift of persistent sea foam in the surf zone. The method uses short time series of video data collected from an alongshore array of pixels. These space-time data are first Fourier transformed to a frequency-wave number spectrum and, finally, to a velocity spectrum. A model of the velocity spectrum is fit to the observed spectrum to estimate the foam drift velocity. Confidence intervals and other measures of the input and output data quality are calculated. Field test comparisons were made against an in situ bidirectional electromagnetic current meter on the basis of 1 month of video data from the 1997 Sandy Duck field experiment. The root mean square error between the two approaches was 0.10 m/s. Linear regression analysis showed the gain between the two instruments to not be statistically different from one. Differences between the surface and interior measurements were compared to forcing mechanisms that may cause surface velocity shear. Velocity offsets and alongshore wind stress were well correlated for cases when waves and wind were not aligned to within ±45°, when wind- and wave-forced currents are reasonably separable. Calculated wind-dependent surface current shear, modeled as a surface boundary layer, correlated well with the observed velocity offsets for observations of nonalignment between wind and waves. This technique can be applied to study large-scale coastal behavior

Indicators of suspended sediment transport dynamics in rivers

Suspended sediment (SS) is a natural component of rivers, but elevated SS concentrations (SSCs) can impact aquatic ecosystems and engineering infrastructures. However, a significant gap remains in predicting SSC dynamics, which are influenced by catchment and climate factors that control sediment erosion, transport and deposition. The research aim is to develop and apply new SS transport dynamics indicators to determine how SSC varies spatially and temporally at a continental scale. Daily SSC data (mg/l) from 1,425 gauging stations in the US were used to calculate indicators of magnitude, frequency and timing (MFT). A filtering approach was applied to calculate frequency indicators that capture SSC events of differing durations. Spatial patterns in indicators were examined and integrated using K-means clustering. High SSC was identified at sites in dry and mountainous regions, but longer-duration SSC events were found in the northern US. The western coastal region and Puerto Rico had consistent timings of high SSC (winter and autumn, respectively). SSC magnitude had a decreasing trend over time across most of the US, but increasing trends were identified for the duration of SSC events. The use of MFT indicators is recommended for future studies to support prediction of climate change impacts on SSC

An optical technique for the measurement of longshore currents

We present an optical method (optical current meter) to measure the longshore component of nearshore surface currents by measuring the alongshore drift of persistent sea foam in the surf zone. The method uses short time series of video data collected from an alongshore array of pixels. These space-time data are first Fourier transformed to a frequency-wave number spectrum and, finally, to a velocity spectrum. A model of the velocity spectrum is fit to the observed spectrum to estimate the foam drift velocity. Confidence intervals and other measures of the input and output data quality are calculated. Field test comparisons were made against an in situ bidirectional electromagnetic current meter on the basis of 1 month of video data from the 1997 Sandy Duck field experiment. The root mean square error between the two approaches was 0.10 m/s. Linear regression analysis showed the gain between the two instruments to not be statistically different from one. Differences between the surface and interior measurements were compared to forcing mechanisms that may cause surface velocity shear. Velocity offsets and alongshore wind stress were well correlated for cases when waves and wind were not aligned to within ±45°, when wind- and wave-forced currents are reasonably separable. Calculated wind-dependent surface current shear, modeled as a surface boundary layer, correlated well with the observed velocity offsets for observations of nonalignment between wind and waves. This technique can be applied to study large-scale coastal behavior