2,685 research outputs found

    Virgo Early-Type Dwarfs in ALFALFA

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    Early-type dwarf galaxies dominate cluster populations, but their formation and evolutionary histories are poorly understood. The ALFALFA (Arecibo Legacy Fast ALFA) survey has completed observations of the Virgo Cluster in the declination range of 6 - 16 degrees. Less than 2% of the early-type dwarf population is detected, a significantly lower fraction than reported in previous papers based on more limited samples. In contrast ~30 of the irregular/BCD dwarf population is detected. The detected early-type galaxies tend to be located in the outer regions of the cluster, with a concentration in the direction of the M Cloud. Many show evidence for ongoing/recent star formation. Galaxies such as these may be undergoing morphological transition due to cluster environmental effects.Comment: 2 pages. To be published in proceedings of IAU Symposium 244: 'Dark Galaxies and Lost Baryons', J. I. Davies & M. D. Disney. eds., Cambridge University Pres

    Aid for trade and the political economy of trade liberalization

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    The Aid for Trade (AfT) initiative has gained much popularity since its launch at the World Trade Organization's Ministerial Conference in 2005, and there are ongoing discussions on its effectiveness and potential to improve the integration of developing countries into the world economy. This paper contributes to the debate by analyzing AfT in a political economy context. We find that the delivery of AfT is a precondition for trade reform in developing countries, as well as for trade liberalization and trade-enhancing rule-making in regional and international forums. Accordingly, AfT may be a catalyst of trade reforms domestically and internationally. --Aid for Trade,Trade Liberalization,Trade Policy,Trade Reform

    Model studies of Helmholtz resonances in rooms with windows and doorways

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    Numerical analysis of Helmholtz resonator system established between windows and open doors when subjected to sonic boom impulsive load

    Veterinary treatment in organic husbandry

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    The organic farming regulations put emphasis on the preservation of animal health by prophylaxis in the agriculture. The No 5 of the regulation EC 1804/99 (EC organic regulation) Appendix I B defines the veterinary treatments in organic animal husbandry. The veterinarian can use any medicine, which is effective for the indication and the animal species. If possible, effective homeopathics, phytotherapeutics or the like should have priority. Problems of implementing the EC organic regulation into the daily farm practice arise mostly from the doubling of the withdrawal period and the restriction of the numbers of treatments. The strict ban on prophylactic treatments is not mentioned any longer in the new regulation 834/2007, which shall apply as from 1st January 2009. Clarification of the guidelines for animal treatments in organic farming seems to be useful for farmers, veterinarians and boards of control

    The cultural shaping of compassion

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    In this chapter, we first review the existing literature on cross-cultural studies on compassion. While cultural similarities exist, we demonstrate cultural differences in the conception, experience, and expression of compassion. Then we present our own work on the cultural shaping of compassion by introducing Affect Valuation Theory ( e.g., Tsai, Knutson, & Fung, 2006), our theoretical framework. We show how the desire to avoid feeling negative partly explains cultural differences in conceptualizations and expressions of compassion. Specifically, the more people want to avoid feeling negative, the more they focus on the positive (e.g., comforting memories) than the negative (e.g., the pain of someone\u27s death) when responding to others\u27 suffering, and the more they regard responses as helpful that focus on the positive (vs. negative). Finally, we discuss implications of our work for counseling, health care, and public service settings, as well as for interventions that aim to promote compassion

    Ram pressure stripping of disc galaxies: The role of the inclination angle

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    We present 3D hydrodynamical simulations of ram pressure stripping of massive disc galaxies in clusters. Studies of galaxies that move face-on have predicted that in such a geometry the galaxy can lose a substantial amount of its interstellar medium. But only a small fraction of galaxies is moving face-on. Therefore, in this work we focus on a systematic study of the effect of the inclination angle between the direction of motion and the galaxy's rotation axis. In agreement with some previous works, we find that the inclination angle does not play a major role for the mass loss as long as the galaxy is not moving close to edge-on. We can predict this behaviour by extending Gunn & Gott's estimate of the stripping radius, which is valid for face-on geometries, to moderate inclinations. The inclination plays a role as long as the ram pressure is comparable to pressures in the galactic plane, which can span two orders of magnitude. For very strong ram pressures, the disc will be stripped completely, and for very weak ram pressures, mass loss is negligible independent of inclination. We show that in non-edge-on geometries the stripping proceeds remarkably similar. A major difference between different inclinations is the degree of asymmetry introduced in the remaining gas disc. We demonstrate that the tail of gas stripped from the galaxy does not necessarily point in a direction opposite to the galaxy's direction of motion. Therefore, the observation of a galaxy's gas tail may be misleading about the galaxy's direction of motion.Comment: 14 pages, 14 figures, submitted to MNRAS. pdf version with high resolution figures available at http://www.faculty.iu-bremen.de/eroediger/PLOTLINKS/eroediger_rps.pd

    Fisher-Wright model with deterministic seed bank and selection

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    Seed banks are a common characteristics to many plant species, which allow storage of genetic diversity in the soil as dormant seeds for various periods of time. We investigate an above-ground population following a Fisher-Wright model with selection coupled with a deterministic seed bank assuming the length of the seed bank is kept constant and the number of seeds is large. To assess the combined impact of seed banks and selection on genetic diversity, we derive a general diffusion model. The applied techniques outline a path of approximating a stochastic delay differential equation by an appropriately rescaled stochastic differential equation, which is a common issue in statistical physics. We compute the equilibrium solution of the site-frequency spectrum and derive the times to fixation of an allele with and without selection. Finally, it is demonstrated that seed banks enhance the effect of selection onto the site-frequency spectrum while slowing down the time until the mutation-selection equilibrium is reached
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