503 research outputs found
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Forecasting Seasonal Habitat Connectivity in a Developing Landscape
Connectivity and wildlife corridors are often key components to successful conservation and management plans. Connectivity for wildlife is typically modeled in a static environment that reflects a single snapshot in time. However, it has been shown that, when compared with dynamic connectivity models, static models can underestimate connectivity and mask important population processes. Therefore, including dynamism in connectivity models is important if the goal is to predict functional connectivity. We incorporated four levels of dynamism (individual, daily, seasonal, and interannual) into an individual-based movement model for black bears (Ursus americanus) in Massachusetts, USA. We used future development projections to model movement into the year 2050. We summarized habitat connectivity over the 32-year simulation period as the number of simulated movement paths crossing each pixel in our study area. Our results predict black bears will further colonize the expanding part of their range in the state and move beyond this range towards the greater Boston metropolitan area. This information is useful to managers for predicting and addressing human–wildlife conflict and in targeting public education campaigns on bear awareness. Including dynamism in connectivity models can produce more realistic models and, when future projections are incorporated, can ensure the identification of areas that offer long-term functional connectivity for wildlife
Municipal Responses to 'Illegality': Urban Sanctuary across National Contexts
Cities often seek to mitigate the highly precarious situation of Illegalized (or undocumented) migrants. In this context, "sanctuary cites" are an innovative urban response to exclusionary national policies. In this article, we expand the geographical scope of sanctuary policies and practices beyond Canada, the USA, and the UK, where the policies and practices are well-known. In particular, we explore corresponding urban initiatives in Chile, Germany, and Spain. We find that varying kinds of urban-sanctuary policies and practices permit illegalized migrants to cope with their situations in particular national contexts. However, different labels, such as "city of refuge," "commune of reception," or "solidarity city" are used to describe such initiatives. While national, historical, and geopolitical contexts distinctly shape local efforts to accommodate illegalized migrants, recognizing similarities across national contexts is important to develop globally-coordinated and internationally-inspired responses at the urban scale
Ice volume distribution and implications on runoff projections in a glacierized catchment
A dense network of helicopter-based ground-penetrating radar (GPR) measurements was used to determine the ice-thickness distribution in the Mauvoisin region. The comprehensive set of ice-thickness measurements was combined with an ice-thickness estimation approach for an accurate determination of the bedrock. A total ice volume of 3.69 &plusmn; 0.31 km<sup>3</sup> and a maximum ice thickness of 290 m were found. The ice-thickness values were then employed as input for a combined glacio-hydrological model forced by most recent regional climate scenarios. This model provided glacier evolution and runoff projections for the period 2010–2100. Runoff projections of the measured initial ice volume distribution show an increase in annual runoff of 4% in the next two decades, followed by a persistent runoff decrease until 2100. Finally, we checked the influence of the ice-thickness distribution on runoff projections. Our analyses revealed that reliable estimates of the ice volume are essential for modelling future glacier and runoff evolution. Wrong estimations of the total ice volume might even lead to deviations of the predicted general runoff trend
A Spectral Line Survey from 138.3 to 150.7 GHZ toward Orion-KL
We present the results of a spectral line survey from 138.3 to 150.7 GHz
toward Orion-KL. The observations were made using the 14 m radio telescope of
Taeduk Radio Astronomy Observatory. Typical system temperatures were between
500 and 700 K, with the sensitivity between K in units of .
A total of 149 line spectra are detected in this survey. Fifty lines have
been previously reported, however we find 99 new detections. Among these new
lines, 32 are `unidentified', while 67 are from molecular transitions with
known identifications. There is no detection of H or He recombination lines.
The identified spectra are from a total of 16 molecular species and their
isotopic variants. In the range from 138.3 to 150.7 GHz, the strongest spectral
line is the J=3-2 transition of CS molecule, followed by transitions of the
, , , and . Spectral lines from
the large organic molecules such as , , , and are prominent; with 80 % of the
identified lines arising from transitions of these molecules. The rotational
temperatures and column densities are derived using the standard rotation
diagram analysis for (), , and with and . These estimates are fairly comparable to the values for the
same molecule in other frequency regions by other studies.Comment: 10 figures, 2 tex files for a manuscript and tables, accepted to Ap
Growth and structure characterization of EuSi₂ films and nanoislands on vicinal Si(001) surface
Social response to population change and migration: the impact of population change on individuals and institutions
Population change over the last 40 years has greatly redistributed Midwest populations. Migration has long been a social response to change—both to changing capacities in the agricultural system and to socio-cultural attractions and opportunities in the urban-industrial areas. Some of the surplus agricultural population has moved to cities and suburbs. The result is a selective dismembering of many communities and an inordinate growth of others.https://lib.dr.iastate.edu/specialreports/1037/thumbnail.jp
Common climatic signal from glaciers in the European Alps over the last 50 years
Conventional glacier-wide mass balances are commonly used to study the effect of climate forcing on glacier melt. Unfortunately, the glacier-wide mass balances are also influenced by the glacier's dynamic response. Investigations on the effects of climate forcing on glaciers can be largely improved by analyzing point mass balances. Using a statistical model, we have found that 52% of the year-to-year deviations in the point mass balances of six glaciers distributed across the entire European Alps can be attributed to a common variability. Point mass balance changes reveal remarkable regional consistencies reaching 80% for glaciers less than 10 km apart. Compared to the steady state conditions of the 1962–1982 period, the surface mass balance changes are −0.85 m water equivalent (w.e.) a⁻¹ for 1983–2002 and −1.63 m w.e. a⁻¹ for 2003–2013. This indicates a clear and regionally consistent acceleration of mass loss over recent decades over the entire European Alps
Rescue and homogenization of 140 years of glacier mass balance data in Switzerland
Glacier monitoring in Switzerland has resulted in some of the longest and most complete data series globally. Mass balance observations at individual locations, starting in the 19th century, are the backbone of the monitoring as they represent the raw and original glaciological data demonstrating the response of snow accumulation and snow/ice melt to changes in climate forcing.
So far, however, the variety of sources of historic measurements has not been systematically processed and documented. Here, we present a new complete and extensive point glacier mass balance dataset for the Swiss Alps that provides attributes for data quality and corresponding uncertainties. Original sources were digitized or re-assessed to validate or to correct existing entries and to identify metadata. The sources of data are highly diverse and stem from almost 140 years of records, originating from handwritten field notes, unpublished project documents, various digital sources, published reports, and meta-knowledge of the observers. The project resulted in data series with metadata for 63 individual Swiss glaciers, including more than 60 000 point observations of mass balance.
Data were systematically analysed and homogenized, e.g. by supplementing partly missing information based on correlations inferred from direct measurements. A system to estimate uncertainty in all individual observations was developed indicating that annual point balance is measured with a typical error of 0.07 m water equivalent (w.e.), while the average error in winter snow measurements is 0.20 m w.e. Our dataset permits further investigating the climate change impacts on Swiss glaciers. Results show an absence of long-term trends in snow accumulation over glaciers while melt rates have substantially increased over the last 3 decades. The complete dataset is available at DOI https://doi.org/10.18750/massbalance.point.2021.r2021 (GLAMOS, 2021).</p
Regional and Annual Variability in Subglacial Sediment Transport by Water for Two Glaciers in the Swiss Alps
Glaciers expel large amounts of water and sediments, and the discharge of both is influenced by glacier retreat. Because the majority of sediment originates subglacially, as opposed to proglacially, focus must be given to subglacial sediment discharge. The latter, however, is poorly constrained. We present a subglacial sediment transport time-series from the Gornergletscher and Aletschgletscher catchments in the Swiss Alps, based on hourly suspended sediment transport data and bedload transport estimates. This dataset is used to identify interannual and regional variability and to quantify the relationship between sediment transport and water discharge. Analysis of the relationship suggests that the access of water to subglacial sediment exerts substantial control on the quantity of sediment discharged. Historical data from Gornergletscher since the 1970's show that elevated amounts of sediment were discharged in the 1980's, following the onset of increasing glacier melt. However, by 2016 and 2017, the sediment discharge had returned to quantities below those in the 1970's, suggesting that sediment discharge may return to an equilibrium over decadal times scales following the onset of a new hydrological regime. Erosion rates for the two catchments (0.28 mm a−1 to 0.49 mm a−1) are lower than in other glacierized catchments of the Swiss Alps (~1 mm a−1). In some years in both catchments, these rates are even less than a third of those reported in earlier decades, highlighting substantial regional and interannual variability in catchment-scale erosion. Empirical models of the relationship between sediment concentration and water discharge, calibrated with the presented 2016–2017 data, fail to capture the elevated sediment discharge over the 1980's. This suggests that processes other than runoff, such as changing access to subglacial sediment by meltwater, were responsible for the increase. Subglacial sediment discharge depends on both water discharge and sediment availability. Therefore, we argue that physically-based models of subglacial sediment transport, that can capture its complex temporal and spatial evolution in response to glacier retreat, are needed to predict and understand a glacier's sediment yield
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