1,050 research outputs found
Predicting species composition in an eastern hardwood forest with the use of digitally derived terrain variables
This thesis addresses the need for improved classification of remotely sensed imagery in the complex hardwood forests of West Virginia. A geographic information system (GIS) was used in conjunction with forest plot data to develop a model to predict species composition in the eastern hardwood forest of West Virginia. The study area was located on the West Virginia University Research Forest (WVURF) in northern West Virginia. Terrain variables including aspect, curvature and slope change drastically at a local scale within the forest to greatly influence species composition. Light Detection and Ranging (LiDAR) data was collected for the entire WVURF, which produced an extremely detailed digital elevation model (DEM), with 1 m spatial resolution. Individual tree crown polygons were created from the LiDAR data so that individual trees could be co-registered to the DEM eliminating the bias of misplaced inventory points. Forest-plot data was collected and each individual tree crown polygon that was created from the LiDAR was assigned actual ground data. Terrain variable values were then sampled for each plot. The data was analyzed using a classification and regression tree (CART) to produce a binomial decision tree that was used within GIS to create a prediction grid of species distribution based on terrain variables. With the decreasing price of data acquisition and with new technology this method is likely to become more widespread and useful to various management agencies
Immigration Enforcement and Fairness to Would-Be Immigrants
This chapter argues that governments have a duty to take reasonably effective and humane steps to minimize the occurrence of unauthorized migration and stay. While the effects of unauthorized migration on a country’s citizens and institutions have been vigorously debated, the literature has largely ignored duties of fairness to would-be immigrants. It is argued here that failing to take reasonable steps to prevent unauthorized migration and stay is deeply unfair to would-be immigrants who are not in a position to bypass visa regulations. Importantly, the argument here is orthogonal to the debate as to how much and what kinds of immigration ought to be allowed
Confronting the Limits of Dialogue: Charlottesville, 2017
Chapter 3: Confronting the Limits of Dialogue: Charlottesville, 2017 in Libraries Promoting Reflective Dialogue in a Time of Political Polarization. ISBN 978-0-8389-4652-
Potential formulation of the dispersion relation for a uniform, magnetized plasma with stationary ions in terms of a vector phasor
The derivation of the helicon dispersion relation for a uniform plasma with
stationary ions subject to a constant background magnetic field is reexamined
in terms of the potential formulation of electrodynamics. Under the same
conditions considered by the standard derivation, the nonlinear self-coupling
between the perturbed electron flow and the potential it generates is
addressed. The plane wave solution for general propagation vector is determined
for all frequencies and expressed in terms of a vector phasor. The behavior of
the solution as described in vacuum units depends upon the ratio of
conductivity to the magnitude of the background field. Only at low conductivity
and below the cyclotron frequency can significant propagation occur as
determined by the ratio of skin depth to wavelength.Comment: 10 pages, 6 figures, major revision, final version, to appear in Po
Multisensory integration supports configural learning of a home refuge in the whip spider \u3ci\u3ePhrynus marginemaculatus\u3c/i\u3e
Predator diets represent a potential interaction between local prey availability, prey antipredator defenses, and predator foraging behavior. Female spider-specialist muddauber wasps (Hymenoptera: Sphecidae) collect spiders and provision them intact, but paralyzed, to their developing larvae, providing a unique means of quantifying the diversity and abundance of prey that they capture. Mud-dauber wasps are hypothesized to be a major source of selection on antipredator defenses in web-building spiders, and the spiny and thickened abdomens of female spiny orb-weaving spiders (Araneae: Araneidae) are hypothesized to function as antiwasp defenses. We inventoried spider prey from nests of the mud-dauber wasps Sceliphron caementarium (Drury) and Chalybion californicum (Saussure), and surveyed for spider fauna in areas surrounding nest collection sites, to specifically investigate if the spiny orb-weaver Micrathena gracilis (Walckenaer) was collected as prey by these wasps. We collected nests from six sites in southeastern Nebraska from two regions that we classify based on habitat—a forest corridor and agricultural land. We collected 761 intact spider prey from 87 nests and identified them to the family level. None of these spiders were M. gracilis. Micrathena gracilis were rare in faunal surveys on agricultural land and, surprisingly, absent in forest corridor surveys. Mud-dauber wasps were more common; we collected more spiders on agricultural land than in the forest corridor. We propose that in agricultural landscapes, the lack of certain spiders in mud-dauber wasp nests is driven by habitat use differences between predators and prey rather than physical antipredator defenses
Stationary and Axisymmetric Solutions of Higher-Dimensional General Relativity
We study stationary and axisymmetric solutions of General Relativity, i.e.
pure gravity, in four or higher dimensions. D-dimensional stationary and
axisymmetric solutions are defined as having D-2 commuting Killing vector
fields. We derive a canonical form of the metric for such solutions that
effectively reduces the Einstein equations to a differential equation on an
axisymmetric D-2 by D-2 matrix field living in three-dimensional flat space
(apart from a subclass of solutions that instead reduce to a set of equations
on a D-2 by D-2 matrix field living in two-dimensional flat space). This
generalizes the Papapetrou form of the metric for stationary and axisymmetric
solutions in four dimensions, and furthermore generalizes the work on Weyl
solutions in four and higher dimensions. We analyze then the sources for the
solutions, which are in the form of thin rods along a line in the
three-dimensional flat space that the matrix field can be seen to live in. As
examples of stationary and axisymmetric solutions, we study the
five-dimensional rotating black hole and the rotating black ring, write the
metrics in the canonical form and analyze the structure of the rods for each
solution.Comment: 43 pages, v2: typos fixed, refs adde
Macrophage migration inhibitory factor downregulation: a novel mechanism of resistance to anti-angiogenic therapy.
Anti-angiogenic therapies for cancer such as VEGF neutralizing antibody bevacizumab have limited durability. While mechanisms of resistance remain undefined, it is likely that acquired resistance to anti-angiogenic therapy will involve alterations of the tumor microenvironment. We confirmed increased tumor-associated macrophages in bevacizumab-resistant glioblastoma patient specimens and two novel glioblastoma xenograft models of bevacizumab resistance. Microarray analysis suggested downregulated macrophage migration inhibitory factor (MIF) to be the most pertinent mediator of increased macrophages. Bevacizumab-resistant patient glioblastomas and both novel xenograft models of resistance had less MIF than bevacizumab-naive tumors, and harbored more M2/protumoral macrophages that specifically localized to the tumor edge. Xenografts expressing MIF-shRNA grew more rapidly with greater angiogenesis and had macrophages localizing to the tumor edge which were more prevalent and proliferative, and displayed M2 polarization, whereas bevacizumab-resistant xenografts transduced to upregulate MIF exhibited the opposite changes. Bone marrow-derived macrophage were polarized to an M2 phenotype in the presence of condition-media derived from bevacizumab-resistant xenograft-derived cells, while recombinant MIF drove M1 polarization. Media from macrophages exposed to bevacizumab-resistant tumor cell conditioned media increased glioma cell proliferation compared with media from macrophages exposed to bevacizumab-responsive tumor cell media, suggesting that macrophage polarization in bevacizumab-resistant xenografts is the source of their aggressive biology and results from a secreted factor. Two mechanisms of bevacizumab-induced MIF reduction were identified: (1) bevacizumab bound MIF and blocked MIF-induced M1 polarization of macrophages; and (2) VEGF increased glioma MIF production in a VEGFR2-dependent manner, suggesting that bevacizumab-induced VEGF depletion would downregulate MIF. Site-directed biopsies revealed enriched MIF and VEGF at the enhancing edge in bevacizumab-naive patients. This MIF enrichment was lost in bevacizumab-resistant glioblastomas, driving a tumor edge M1-to-M2 transition. Thus, bevacizumab resistance is driven by reduced MIF at the tumor edge causing proliferative expansion of M2 macrophages, which in turn promotes tumor growth
Horn-Coupled, Commercially-Fabricated Aluminum Lumped-Element Kinetic Inductance Detectors for Millimeter Wavelengths
We discuss the design, fabrication, and testing of prototype horn-coupled,
lumped-element kinetic inductance detectors (LEKIDs) designed for cosmic
microwave background (CMB) studies. The LEKIDs are made from a thin aluminum
film deposited on a silicon wafer and patterned using standard
photolithographic techniques at STAR Cryoelectronics, a commercial device
foundry. We fabricated twenty-element arrays, optimized for a spectral band
centered on 150 GHz, to test the sensitivity and yield of the devices as well
as the multiplexing scheme. We characterized the detectors in two
configurations. First, the detectors were tested in a dark environment with the
horn apertures covered, and second, the horn apertures were pointed towards a
beam-filling cryogenic blackbody load. These tests show that the multiplexing
scheme is robust and scalable, the yield across multiple LEKID arrays is 91%,
and the noise-equivalent temperatures (NET) for a 4 K optical load are in the
range 26\thinspace\pm6 \thinspace \mu \mbox{K} \sqrt{\mbox{s}}
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