3,818 research outputs found

    A Comparison of AVIRIS and Landsat for Land Use Classification at the Urban Fringe

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    In this study we tested whether AVIRIS data allowed for improved land use classification over synthetic Landsat ETM+ data for a location on the urban-rural fringe of Colorado. After processing the AVIRIS image and creating a synthetic Landsat image, we used standard classification and post-classification procedures to compare the data sources for land use mapping. We found that, for this location, AVIRIS holds modest, but real, advantages over Landsat for the classification of heterogeneous and vegetated land uses. Furthermore, this advantage comes almost entirely from the large number of sensor spectral bands rather than the high Signal-to-Noise Ratio (SNR)

    Estimating the Creation and Removal Date of Fracking Ponds Using Trend Analysis of Landsat Imagery

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    Hydraulic fracturing, or fracking, is a process of introducing liquid at high pressure to create fractures in shale rock formations, thus releasing natural gas. Flowback and produced water from fracking operations is typically stored in temporary open-air earthen impoundments, or frack ponds. Unfortunately, in the United States there is no public record of the location of impoundments, or the dates that impoundments are created or removed. In this study we use a dataset of drilling-related impoundments in Pennsylvania identified through the FrackFinder project led by SkyTruth, an environmental non-profit. For each impoundment location, we compiled all low cloud Landsat imagery from 2000 to 2016 and created a monthly time series for three bands: red, near-infrared (NIR), and the Normalized Difference Vegetation Index (NDVI). We identified the approximate date of creation and removal of impoundments from sudden breaks in the time series. To verify our method, we compared the results to date ranges derived from photointerpretation of all available historical imagery on Google Earth for a subset of impoundments. Based on our analysis, we found that the number of impoundments built annually increased rapidly from 2006 to 2010, and then slowed from 2010 to 2013. Since newer impoundments tend to be larger, however, the total impoundment area has continued to increase. The methods described in this study would be appropriate for finding the creation and removal date of a variety of industrial land use changes at known locations

    Control system for hunger and its implications in animals and man

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    Migrant Farmworkers\u27 Perceptions of Pesticide Risk Exposure in Adams County, Pennsylvania: A Cultural Risk Assessment

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    Agricultural exceptionalism, a system in which regular labor laws and standards do not apply to farm labor, makes migrant farmworkers particularly vulnerable populations—economically, socially, and in terms of environmental health. To address inequities inherent in migrant farmworker margin­aliza­tion, studies advocate for actively engaging the migrant farmworker population in the conversation surrounding these issues. We conducted 40 semi­structured interviews with migrant farmworkers in Adams County, Pennsylvania, to understand pesti­cide risk exposure perceptions and practices. We employed the Health Belief Model as our cultural risk assessment frame, using it in combination with technical risk assessment, which uses government calculations (from the Environmental Protection Agency) to quantify pesticide risk exposure. We used mixed methods analyses (quantitative and qualitative) to compare and understand farmworker demographics, perceived risk, perceived control, and risk behavior. Results show that demo­graphics —e.g., age, education, visa status—are important factors in risk perception. They also confirm observations present in many earlier studies. While trainings and educational materials are valuable to help build awareness of risk, a systemic lack of control over their circumstances make it hard for migrant farmworkers to engage in safe behavior. Results also highlight the limitations of technical risk assessment. Such calculations, however, rarely account for risk perceptions and experiences of farm­workers themselves. Acknowledging the voices of migrant farmworkers is an essential first step in rebalancing inequities of power in our food systems, and cultural risk assessment can help frame recommendations that target different stake­holders across the pesticide regulatory spectrum to ensure migrant farmworker needs and safety

    Detailed Geant4 simulations of the ANITA and ANITA-CUP neutron facilities

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    Simulations of the ANITA spallation neutron source at The Svedberg Laboratory (TSL) are described. Neutron radiation calculations show close agreement with measurements at both standard and close user positions. Gamma radiation characteristics are also predicted

    Letter from H. V. Platt to [John Muir], [ca. 1907].

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    Form 2191 C. B. After transmitting telegrams which in their judgment would have served the Company\u27s interest if sent by train mail, or appear unnecessarily long operators are required to attach a copy of them to proper Form and forward and forward same to Superintendent of Telegraph.3:10PM Pink Yum8 13thCendr No 8.Please advice Mr. John Muir on your train wait at ImperialJet for Mr. Hrrimans Special.H V Platt0400

    The Effect of Internal Migration on Local Labor Markets: American Cities During the Great Depression

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    During the Great Depression, as today, migrants were accused of taking jobs and crowding relief rolls. At the time, protest concerned internal migrants rather than the foreign born. We investigate the effect of net migration on local labor markets, instrumenting for migrant flows to a destination with extreme weather events and variation in New Deal programs in typical sending areas. Migration had little effect on the hourly earnings of existing residents. Instead, migration prompted some residents to move away and others to lose weeks of work and/or access to relief jobs. Given the period's high unemployment, these lost work opportunities were costly to existing residents.

    Differences between European birthweight standards: impact on classification of ‘small for gestational age’

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    We describe a quantitative and comparative review of a selection of European birthweight standards for gestational age for singletons, to enable appropriate choices to be made for clinical and research use. Differences between median values at term across standards in 10 regions and misclassification of ‘small for gestational age’ (SGA), were studied. Sex and parity differences, exclusion criteria, and methods of construction were considered. There was wide variation between countries in exclusion criteria, methods of calculating standards, and median birthweight at term. The lightest standards (e.g. France's medians are 255g lower than Norway's medians) were associated with fewer exclusion criteria. Up to 20% of the population used in the construction of the Scottish standard would be classified as SGA using the Norwegian standard. Substantial misclassification of SGA is possible. Assumptions about variation used in the construction of some standards were not justified. It is not possible to conclude that there are real differences in birthweight standards between European countries. Country-based standards control for some population features but add misclassification due to the differing ways in which standards are derived. Standards should be chosen to reflect clinical or research need. If standards stratified by sex or parity are not available, adjustments should be made. In multinational studies, comparisons should be made between results using both a common standard and country-based standards

    Exploring barriers to 'Respondent driven sampling' in sex worker and drug-injecting sex worker populations in Eastern Europe

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    Respondent driven sampling (RDS) has been used in several counties to sample injecting drug users, sex workers (SWs) and men who have sex with men and as a means of collecting behavioural and biological health data. We report on the use of RDS in three separate studies conducted among SWs between 2004 and 2005 in the Russian Federation, Serbia, and Montenegro. Findings suggest that there are limitations associated with the use of RDS in SW populations in these regions. Findings highlight three main factors that merit further investigation as a means of assessing the feasibility and appropriateness of RDS in this high risk population: the network characteristics of SWs; the appropriate level of participant incentives; and lack of service contact. The highly controlled and hidden nature of SW organizations and weak SW social networks in the region can combine to undermine assumptions underpinning the feasibility of RDS approaches and potentially severely limit recruitment. We discuss the implications of these findings for recruitment and the use of monetary and non-monetary incentives in future RDS studies of SW populations in Eastern Europe
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