Low-energy elastic electron scattering by acetylene

We report measurements and first-principles calculations of the differential cross sections for elastic scattering of low-energy electrons by acetylene, C_2H_2, at collision energies from 1 to 100 eV, with an emphasis on energies near and below that of the π* shape resonance. The measurements cover angles from 5° to 130°. We compare our results to previous experimental and theoretical values

Instability of insular tree communities in an Amazonian mega-dam is driven by impaired recruitment and altered species composition

Mega-dams create highly fragmented archipelagos, affecting biodiversity and ecosystem functioning in remnant forest isolates. This study assessed the long-term impact of dam-induced fragmentation on insular tropical tree communities, with the aim of generating robust recommendations to mitigate some of the detrimental biodiversity impacts associated with future dam development. We inventoried adult and sapling trees across 89 permanent plots, located on 36 islands and in three mainland continuous forest sites in the Balbina Dam, Brazilian Amazon. We examined differences in recruitment, structure, and composition of sapling and adult tree communities, in relation to plot-, patch- and landscape-scale attributes including area, isolation, and fire severity. Islands harboured significantly lower sapling (mean ± 95% CI 48.6 ± 3.8) and adult (5 ± 0.2) tree densities per 0.01 ha, than nearby mainland continuous forest (saplings, 65.7 ± 7.5; adults, 5.6 ± 0.3). Insular sapling and adult tree communities were more dissimilar than in mainland sites, and species compositions showed a directional shift away from mainland forests, induced by fire severity, island area, and isolation. Insular sapling recruitment declined with increasing fire severity; tree communities with higher community-weighted mean wood density showed the greatest recruitment declines. Our results suggest that insular tree communities are unstable, with rare species becoming extinction-prone due to reduced tree recruitment and density on islands, potentially leading to future losses in biodiversity and ecosystem functioning across Balbina's >3,500 reservoir islands. Policy implications. In Balbina, fire and reduced habitat area and connectivity were drivers of tree community decay after only 28 years of insularization, despite strict protection provided by the ~940,000 ha Uatumã Biological Reserve. Given that many dams are planned for lowland, moderately undulating Amazonia, we recommend that dam development strategy explicitly considers (a) dam location, aiming to minimize creation of small (<10 ha) and isolated islands, (b) maintaining reservoir water levels during droughts to reduce fire risk, and (c) including aggregate island area in environmental impact and offset calculations. Ideally, we recommend that alternatives to hydropower be sought in lowland tropical regions, due to the far-reaching biodiversity losses and ecosystem disruption caused by river impoundment

Community‐wide validation of geospace model ground magnetic field perturbation predictions to support model transition to operations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98787/1/swe20056.pd

Validation of a Medicare Claims-based Algorithm for Identifying Breast Cancers Detected at Screening Mammography

The breast cancer detection rate is a benchmark measure of screening mammography quality, but its computation requires linkage of mammography interpretive performance information with cancer incidence data. A Medicare claims-based measure of detected breast cancers could simplify measurement of this benchmark and facilitate mammography quality assessment and research

Insights from wildfire science: A resource for fire policy discussions

Record blazes swept across parts of the US in 2015, burning more than 10 million acres. The four biggest fire seasons since 1960 have all occurred in the last 10 years, leading to fears of a ‘new normal’ for wildfire. Fire fighters and forest managers are overwhelmed, and it is clear that the policy and management approaches of the past will not suffice under this new era of western wildfires. In recent decades, state and federal policymakers, tribes, and others are confronting longer fire seasons (Jolly et al. 2015), more large fires (Dennison et al. 2014), a tripling of homes burned, and a doubling of firefighter deaths (Rasker 2015). Federal agencies now spend $2 to$3 billion annually fighting fires (and in the case of the US Forest Service, over 50% of their budget), and the total cost to society may be up to 30 times more than the direct cost of firefighting. If we want to contain these costs and reduce risks to communities, economies, and natural systems, we can draw on the best available science when designing fire management strategies, as called for in the recent federal report on Wildland Fire Science and Technology. Here, we highlight key science insights that can contribute to the public discourse on wildfire policy and associated management of forests, woodlands, and shrublands. This information is fundamental to decisions that will promote resilient communities and landscapes facing more fire in the future

Segmentation of Skin Lesions Using Level Set Method

Diagnosis of skin cancers with dermoscopy has been widely accepted as a clinical routine. However, the diagnostic accuracy using dermoscopy relies on the subjective judgment of the dermatologist. To solve this problem, a computer-aided diagnosis system is demanded. Here, we propose a level set method to fulfill the segmentation of skin lesions presented in dermoscopic images. The differences between normal skin and skin lesions in the color channels are combined to define the speed function, with which the evolving curve can be guided to reach the boundary of skin lesions. The proposed algorithm is robust against the influences of noise, hair, and skin textures, and provides a flexible way for segmentation. Numerical experiments demonstrated the effectiveness of the novel algorithm

Community‐wide validation of geospace model local K‐index predictions to support model transition to operations

We present the latest result of a community‐wide space weather model validation effort coordinated among the Community Coordinated Modeling Center (CCMC), NOAA Space Weather Prediction Center (SWPC), model developers, and the broader science community. Validation of geospace models is a critical activity for both building confidence in the science results produced by the models and in assessing the suitability of the models for transition to operations. Indeed, a primary motivation of this work is supporting NOAA/SWPC’s effort to select a model or models to be transitioned into operations. Our validation efforts focus on the ability of the models to reproduce a regional index of geomagnetic disturbance, the local K‐index. Our analysis includes six events representing a range of geomagnetic activity conditions and six geomagnetic observatories representing midlatitude and high‐latitude locations. Contingency tables, skill scores, and distribution metrics are used for the quantitative analysis of model performance. We consider model performance on an event‐by‐event basis, aggregated over events, at specific station locations, and separated into high‐latitude and midlatitude domains. A summary of results is presented in this report, and an online tool for detailed analysis is available at the CCMC.Key PointsReport community‐wide model validation resultsEvaluate ability of models to predict a local index of magnetic perturbationAnalysis directly led to selection of models to transition to operations at NOAA/SWPCPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134170/1/swe20333-sup-0001-supplementary.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134170/2/swe20333_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134170/3/swe20333.pd

Low-energy elastic electron scattering by acetaldehyde

We report results from a combined experimental and computational study of low-energy electron interactions with acetaldehyde in the gas phase. Differential cross sections for elastic electron scattering were measured at selected incident energies from 1 to 50 eV, while corresponding first-principles calculations were carried out up to 30 eV. Integral and momentum-transfer cross sections were derived from the angle-differential data. The role of resonances in the scattering is examined and comparison is made to previous results for acetaldehyde and for its analogs, formamide and formic acid