The Extent Of Wetland Vegetation And Wetness Change At Eufaula National Wildlife Refuge From 1984-2012 Examined Using Landsat Thematic Mapper And Enhanced Thematic Mapper Plus Imagery

Wetlands provide functions such as reducing flooding of surrounding areas and acting as a rest stop for migrating birds. Eufaula National Wildlife Refuge in Alabama has a natural wetland and six artificial wetlands that are differentiated by how they are drained. Remote sensing derived normalized difference vegetation index and normalized difference wetness indexes were used to obtain information about vegetation and wetness at the wetlands from 1984-2011. A correlation analysis was performed to assess the degree of association between vegetation and wetness as a function of management practices. An ANOVA and agglomerative hierarchical clustering were performed to assess the degree of similarity among the different wetlands based on vegetation and wetness. From the results of the correlation analysis, it was found that there is a statistically significant association between vegetation and wetness. The ANOVA and agglomerative hierarchical clustering suggest that wetlands that are managed similarly have a similar association between vegetation and wetness

Graphs, Matrices, and the GraphBLAS: Seven Good Reasons

The analysis of graphs has become increasingly important to a wide range of applications. Graph analysis presents a number of unique challenges in the areas of (1) software complexity, (2) data complexity, (3) security, (4) mathematical complexity, (5) theoretical analysis, (6) serial performance, and (7) parallel performance. Implementing graph algorithms using matrix-based approaches provides a number of promising solutions to these challenges. The GraphBLAS standard (istc- bigdata.org/GraphBlas) is being developed to bring the potential of matrix based graph algorithms to the broadest possible audience. The GraphBLAS mathematically defines a core set of matrix-based graph operations that can be used to implement a wide class of graph algorithms in a wide range of programming environments. This paper provides an introduction to the GraphBLAS and describes how the GraphBLAS can be used to address many of the challenges associated with analysis of graphs.Comment: 10 pages; International Conference on Computational Science workshop on the Applications of Matrix Computational Methods in the Analysis of Modern Dat

The Feasibility of Using Data-Driven Algorithmic Recommendations for Refugee Placement in Norway

A growing body of research suggests that refugees’ initial settlement area can have a long-run impact on subsequent integration outcomes. As a result, matching refugees and asylum seekers to initial locations where they are likely to succeed holds the potential to improve their labor market integration. In this report we focus on the GeoMatch algorithm, which is a recommendation tool that provides settlement officers with data-driven location recommendations for incoming refugees and asylum seekers. Leveraging machine learning on historical data, the tool predicts labor market outcomes for individuals across possible settlement areas. A flexible allocation algorithm then provides location recommendations for each family unit while taking capacity constraints into account. Drawing on administrative data from Statistics Norway and incorporating a set of realistic constraints, we find that using GeoMatch recommendations could improve refugees’ monthly earnings by up to 55% over baseline. The report ends with a discussion of how the tool can be implemented in the Norwegian context.The Feasibility of Using Data-Driven Algorithmic Recommendations for Refugee Placement in NorwaypublishedVersio

On the Independent Domination Number of Regular Graphs

A set S of vertices in a graph G is an independent dominating set of G if S is an independent set and every vertex not in S is adjacent to a vertex in S. In this paper, we consider questions about independent domination in regular graphs

Attention-deficit hyperactivity disorder symptoms and brain morphology:Addressing potential selection bias with inverse probability weighting

The goal of this study was to examine what happens to established associations between attention deficit hyperactivity disorder (ADHD) symptoms and cortical surface and thickness regions once we apply inverse probability of censoring weighting (IPCW) to address potential selection bias. Moreover, we illustrate how different factors that predict participation contribute to potential selection bias. Participants were 9- to 11-year-old children from the Generation R study (N = 2707). Cortical area and thickness were measured with magnetic resonance imaging (MRI) and ADHD symptoms with the Child Behavior Checklist. We examined how associations between ADHD symptoms and brain morphology change when we weight our sample back to either follow-up (ages 9–11), baseline (cohort at birth), or eligible (population of Rotterdam at time of recruitment). Weights were derived using IPCW or raking and missing predictors of participation used to estimate weights were imputed. Weighting analyses to baseline and eligible increased beta coefficients for the middle temporal gyrus surface area, as well as fusiform gyrus cortical thickness. Alternatively, the beta coefficient for the rostral anterior cingulate decreased. Removing one group of variables used for estimating weights resulted in the weighted regression coefficient moving closer to the unweighted regression coefficient. In addition, we found considerably different beta coefficients for most surface area regions and all thickness measures when we did not impute missing covariate data. Our findings highlight the importance of using inverse probability weighting (IPW) in the neuroimaging field, especially in the context of mental health-related research. We found that including all variables related to exposure-outcome in the IPW model and combining IPW with multiple imputations can help reduce bias. We encourage future psychiatric neuroimaging studies to define their target population, collect information on eligible but not included participants and use inverse probability of censoring weighting (IPCW) to reduce selection bias.</p

Attention-deficit hyperactivity disorder symptoms and brain morphology:Addressing potential selection bias with inverse probability weighting

The goal of this study was to examine what happens to established associations between attention deficit hyperactivity disorder (ADHD) symptoms and cortical surface and thickness regions once we apply inverse probability of censoring weighting (IPCW) to address potential selection bias. Moreover, we illustrate how different factors that predict participation contribute to potential selection bias. Participants were 9- to 11-year-old children from the Generation R study (N = 2707). Cortical area and thickness were measured with magnetic resonance imaging (MRI) and ADHD symptoms with the Child Behavior Checklist. We examined how associations between ADHD symptoms and brain morphology change when we weight our sample back to either follow-up (ages 9–11), baseline (cohort at birth), or eligible (population of Rotterdam at time of recruitment). Weights were derived using IPCW or raking and missing predictors of participation used to estimate weights were imputed. Weighting analyses to baseline and eligible increased beta coefficients for the middle temporal gyrus surface area, as well as fusiform gyrus cortical thickness. Alternatively, the beta coefficient for the rostral anterior cingulate decreased. Removing one group of variables used for estimating weights resulted in the weighted regression coefficient moving closer to the unweighted regression coefficient. In addition, we found considerably different beta coefficients for most surface area regions and all thickness measures when we did not impute missing covariate data. Our findings highlight the importance of using inverse probability weighting (IPW) in the neuroimaging field, especially in the context of mental health-related research. We found that including all variables related to exposure-outcome in the IPW model and combining IPW with multiple imputations can help reduce bias. We encourage future psychiatric neuroimaging studies to define their target population, collect information on eligible but not included participants and use inverse probability of censoring weighting (IPCW) to reduce selection bias.</p

Preparing for operation GRITROCK : military medical ethics challenges encountered in the planning stages of the UK Ebola response mission

In early September 2014, Médecins sans Frontières (MSF) took the unusual step of calling on governments to deploy military, as well as civilian, assets to help combat the Ebola Virus Disease (EVD) epidemic raging in West Africa (MSF, 2014). The UK government announced a package of aid in response to the outbreak, including the deployment of military experts, targeted primarily on Sierra Leone. (Gov.UK 2014) The scale of the outbreak and the responses to it attracted comment from many quarters and raised ethical issues. We were interested in the ethical challenges that would confront the troops on the ground in Sierra Leone, particularly those who were healthcare professionals. We successfully secured UK funding council research funds to explore these challenges. During the preparatory stages of this project, however, it became clear that ethical decisions had also been made during the planning stages of the deployment in anticipation of issue that may be faced on the deployment. These planning issues are of interest in their own right, even though they fell outside the aims of our project, and we explore of some these in this chapter

Panchromatic Imaging of a Transitional Disk: The Disk of GM Aur in Optical and FUV Scattered Light

We have imaged GM Aur with HST, detected its disk in scattered light at 1400A and 1650A, and compared these with observations at 3300A, 5550A, 1.1 microns, and 1.6 microns. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300A shows no evidence of the 24AU radius cavity that has been previously observed in sub-mm observations. Comparison with dust grain opacity models indicates the surface of the entire disk is populated with sub-micron grains. We have compiled an SED from 0.1 microns to 1 mm, and used it to constrain a model of the star+disk system that includes the sub-mm cavity using the Monte Carlo Radiative Transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of sub-microns grains interior to the sub-mm cavity wall. We suggest one explanation for this which could be due to a planet of mass <9 Jupiter masses interior to 24 AU. A unique cylindrical structure is detected in the FUV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semi-minor axis, but does not resemble an accretion-driven jet. The structure is limb-brightened and extends 190 +/- 35 AU above the disk midplane. The inner radius of the limb-brightening is 40 +/- 10 AU, just beyond the sub-millimeter cavity wall.Comment: 40 pages, 11 figures, 4 tables, accepted to Ap

Low-Mass Proto-Planet Migration in T-Tauri Alpha-Disks

We present detailed estimates of ''type-I'' migration rates for low-mass proto-planets embedded in steady-state T-Tauri alpha-disks, based on Lindblad torque calculations ignoring feedback on the disk. Differences in migration rates for several plausible background disk models are explored and we contrast results obtained using the standard two dimensional formalism of spiral density wave theory with those obtained from a simple treatment of three-dimensional effects. Opacity transitions in the disk result in sudden radial variations of the migration rates. Regions with minimal migration rates may be preferred sites of gravitational interactions between proto-planets. Three-dimensional torques are significantly weaker than two-dimensional ones and they are sensitive to the surface density profile of the background disk. We find that migration times in excess of runaway envelope accretion times or T-Tauri disk lifetimes are possible for Earth-mass proto-planets in some background disk models, even at sub-AU distances. We conclude that an understanding of the background disk structure and ''viscosity'', as well as a proper treatment of three-dimensional effects in torque calculations, are necessary to obtain reliable estimates of ``type-I'' migration rates.Comment: Minor revisions, 31 pages, 7 figures, accepted for publication in Ap