A comparison of incompressible limits for resistive plasmas

The constraint of incompressibility is often used to simplify the magnetohydrodynamic (MHD) description of linearized plasma dynamics because it does not affect the ideal MHD marginal stability point. In this paper two methods for introducing incompressibility are compared in a cylindrical plasma model: In the first method, the limit $\gamma \to \infty$ is taken, where $\gamma$ is the ratio of specific heats; in the second, an anisotropic mass tensor $\mathbf{\rho}$ is used, with the component parallel to the magnetic field taken to vanish, $\rho_{\parallel} \to 0$. Use of resistive MHD reveals the nature of these two limits because the Alfv\'en and slow magnetosonic continua of ideal MHD are converted to point spectra and moved into the complex plane. Both limits profoundly change the slow-magnetosonic spectrum, but only the second limit faithfully reproduces the resistive Alfv\'en spectrum and its wavemodes. In ideal MHD, the slow magnetosonic continuum degenerates to the Alfv\'en continuum in the first method, while it is moved to infinity by the second. The degeneracy in the first is broken by finite resistivity. For numerical and semi-analytical study of these models, we choose plasma equilibria which cast light on puzzling aspects of results found in earlier literature.Comment: 14 pages, 10 figure

Osteology and myology of the head and neck of the pied-billed grebes (Podilymbus)

http://deepblue.lib.umich.edu/bitstream/2027.42/56383/1/MP139.pd

Protein Kinase D-Mediated Anterograde Membrane Trafficking Is Required for Fibroblast Motility

AbstractBackground: Locomoting cells exhibit a constant retrograde flow of plasma membrane (PM) proteins from the leading edge lamellipodium backward, which when coupled to substrate adhesion, may drive forward cell movement. However, the intracellular source of these PM components and whether their continuous retrograde flow is required for cell motility is unknown.Results: To test the hypothesis that the anterograde secretion pathway supplies PM components for retrograde flow that are required for lamellipodial activity and cell motility, we specifically inhibited transport of cargo from the trans-Golgi network (TGN) to the PM in Swiss 3T3 fibroblasts and monitored cell motility using time-lapse microscopy. TGN-to-PM trafficking was inhibited with a dominant-negative, kinase-dead (kd) mutant of protein kinase D1 (PKD) that specifically blocks budding of secretory vesicles from the TGN and does not affect other transport pathways. Inhibition of PKD on the TGN inhibited directed cell motility and retrograde flow of surface markers and filamentous actin, while inhibition of PKD elsewhere in the cell neither blocked anterograde membrane transport nor cell motile functions. Exogenous activation of Rac1 in PKD-kd-expressing cells restored lamellipodial dynamics independent of membrane traffic. However, lamellipodial activity was delocalized from a single leading edge, and directed cell motility was not fully recovered.Conclusions: These results indicate that PKD-mediated anterograde membrane traffic from the TGN to the PM is required for fibroblast locomotion and localized Rac1-dependent leading edge activity. We suggest that polarized secretion transmits cargo that directs localized signaling for persistent leading edge activity necessary for directional migration

Long-term Benefits of GM crops: Potential for Diabrotica Suppression in Europe using Bt Maize

Transgenic crops producing insecticidal proteins from _Bacillus thuringiensis_ (Bt) have been widely adopted since 1996 in the United States of America to combat important pests of maize and cotton. There is growing evidence that several target pest populations have been dramatically reduced in areas where the Bt crops have been most intensively adopted over multiple years. The evidence is most dramatic for nonmigratory monophagous and oligophagous species that show high mortality on Bt crops, such as European corn borer (_Ostrinia nubilalis_), and tobacco budworm (_Heliothis virescens_). Bt cotton is currently being used in the southwestern USA as part of an area-wide eradication program for pink bollworm (_Pectinophora gossypiella_). Single, stacked, and pyramided Bt maize lines producing coleopteran-active insecticidal proteins have been shown in some cases to cause >99% mortality of western corn rootworm (_Diabrotica virgifera virgifera_) larvae every year. Simulation models suggest that long-term area-wide cultivation of these Bt corn lines can lead to dramatic population reduction, and even local extinction, of corn rootworms. An eradication program for this economically important pest, based around Bt maize and incorporating a combination of other tools, would benefit European agriculture and the environment. Post-commercial monitoring programs should be designed to investigate long-term benefits to agricultural production systems that can be reasonably expected from the widespread cultivation of Bt crops in Europe

The Situational-Cognitive Model of Adolescent Bystander Behavior: Modeling Bystander Decision-Making in the Context of Bullying and Teen Dating Violence.

Objective: Despite the proliferation of bystander approaches to prevent aggression among youth, theoretical models of violence-related bystander decision making are underdeveloped, particularly among adolescents. The purpose of this research was to examine the utility of 2 theories, the Situational Model of Bystander behavior (SMB) and the Theory of Planned Behavior (TPB), for identifying mechanisms underlying adolescent bystander behavior in the context of bullying and teen dating violence (TDV). Method: Data were collected via face to face (local) and online (national) focus groups with 113 U.S. adolescents aged 14-18 and were subsequently analyzed using deductive and inductive coding methods. Results: Youth endorsed beliefs consistent with both the SMB and TPB and with additional constructs not captured by either theory. Adolescents reported a higher proportion of barriers relative to facilitators to taking action, with perceptions of peer norms and social consequences foremost among their concerns. Many influences on bystander behavior were similar across TDV and bullying. Implications: Findings are organized into the proposed Situational-Cognitive Model of Adolescent Bystander Behavior, which synthesizes the SMB and TPB, and supports the tailoring of bystander interventions. For teens, intervening is a decision about whether and how to navigate potential social consequences of taking action that unfold over time; intervention approaches must assess and acknowledge these concerns. (PsycINFO Database Record (c) 2016 APA, all rights reserved

A Pilot Study of Transplanting Methods for Wilding American Beech (Fagus grandifolia)

American beech is facing pressure from a number of emergent health issues including beech bark disease, beech leaf disease, beech leaf mining weevil, and climate and habitat change. Interest has increased in the propagation of American beech in response to the demand for more disease-resistant American beech for use in restoration. This study describes the first steps towards publishing methods for transplanting beech in order to supplement commercially available beech seedlings in an area with multiple agencies depleting the existing stock of slow growing species. American beech seedlings were purchased from a nursery in northern Michigan and were excavated from natural stands in the Hiawatha National Forest. Survival rates for these cohorts were compared after a growing season and by the relative amounts of fine roots present on the trees. Generally, the wildling seedlings had a higher survivability than the purchased bare root seedlings. Future work is proposed that could clarify the conditions leading to the higher survival in these wildling seedlings, including the potential for handling the time or age of the seedlings to influence survival

Are all my volunteers here to help out? Clustering events volunteers by their motivations

Posed as a question that an event organizer might contemplate in terms of how best to attract and retain event volunteers, this study adds to the event volunteering literature by cluster analysing volunteers sampled at four sports events using items from the Special Event Volunteer Motivation Scale (SEVMS). The 28 items were first subjected to Exploratory Factor Analysis resulting in four factors (Solidary, Purposive, External Traditions/Commitments, and Spare Time), followed by a two-step clustering procedure and a series of post hoc tests to describe and validate the clusters. As a result of this procedure, three distinct clusters were formed: the Altruists, Socials, and Indifferents. The Altruists and Socials were primarily driven by two distinct internal factors, which respectively represented the Purposive and Solidary factors. The Indifferents appeared to be pushed into volunteering by external forces, rather than intrinsic motivations. Validation revealed that the Indifferents were significantly less satisfied with their volunteer experience than the other two clusters and were also less likely to volunteer in the future. Across the four events sampled, there were distinct patterns of cluster representation, with one event in particular substantially overrepresented by the more negatively inclined Indifferents. The management and research implications of these findings are discussed

Simulations of Dense Atomic Hydrogen in the Wigner Crystal Phase

Path integral Monte Carlo simulations are applied to study dense atomic hydrogen in the regime where the protons form a Wigner crystal. The interaction of the protons with the degenerate electron gas is modeled by Thomas-Fermi screening, which leads to a Yukawa potential for the proton-proton interaction. A numerical technique for the derivation of the corresponding action of the paths is described. For a fixed density of rs=200, the melting is analyzed using the Lindemann ratio, the structure factor and free energy calculations. Anharmonic effects in the crystal vibrations are analyzed.Comment: Proceedings article of the Study of Matter at Extreme Conditions (SMEC) conference in Miami, Florida; submitted to Journal of Physics and Chemistry of Solids (2005

Regulation of steroid hormone receptor function by the 52-kDa FK506-binding protein (FKBP52)

The large FK506-binding protein FKBP52 has been characterized as an important positive regulator of androgen, glucocorticoid and progesterone receptor signaling pathways. FKBP52 associates with receptor-Hsp90 complexes and is proposed to have roles in both receptor hormone binding and receptor subcellular localization. Data from biochemical and cellular studies have been corroborated in whole animal models as fkbp52-deficient male and female mice display characteristics of androgen, glucocorticoid and/or progesterone insensitivity. FKBP52 receptor specificity and the specific phenotypes displayed by the fkbp52-deficient mice have firmly established FKBP52 as a promising target for the treatment of a variety of hormone-dependent diseases. Recent studies demonstrated that the FKBP52 FK1 domain and the proline-rich loop within this domain are functionally important for FKBP52 regulation of receptor function. Based on these data, efforts are currently underway to target the FKBP52 FK1 domain and the proline-rich loop with small molecule inhibitors.Fil: Sivils, Jeffrey C. University Of Texas At El Paso; Estados UnidosFil: Storer, Cheryl L.. University Of Texas At El Paso; Estados UnidosFil: Galigniana, Mario Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Cox, Marc B.. University Of Texas At El Paso; Estados Unido

Methotrexate-induced cutaneous ulceration in patients with erythrodermic mycosis fungoides

Methotrexate-induced cutaneous ulceration has rarely been reported in patients with mycosis fungoides. We report 4 patients with mycosis fungoides who developed cutaneous ulceration as an initial manifestation of methotrexate toxicity. Methotrexate dose at the time of ulceration ranged from 10–60 mg. All 4 patients were erythrodermic, which may have predisposed them to this toxic effect. It is important to recognize cutaneous ulceration as an uncommon, but potentially serious, side effect of methotrexate in these patients, and to differentiate it from ulceration due to progressive lymphoma