Browsing by Subject "movement"
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Item AMS :: ATX October 2011 Blog Archive(2011-10) Department of American StudiesAMS :: ATX is a blog dedicated to representing the many activities and interests of the department of American Studies at The University of Texas at Austin. Together with the department’s Twitter feed, this blog exists to serve the AMS and Austin communities by acting as a hub for up-to-date information on events and opportunities at UT and beyond. This archive includes the following blog posts: Read This: The Carbon Diaries (October 5, 2011); Watch This: Time Lapse of Migrant Mother (in pumpkin form!) (October 12, 2011); 5 Questions with Dr. Karl Hagstrom Miller (October 19, 2011); List: Top Picks at the Texas Book Festival (October 20, 2011); American Studies and Occupy Wall Street (October 25, 2011); Grad Research: AMS Dissertations Infographic, 2010-2011 (October 27, 2011).Item The Changing World Of Mental Measurement And Its Social Significance(Hogg Foundation for Mental Health, 1971) Hotlzman, Wayne H.Item The Effect Of Travel Loss On Evolutionarily Stable Distributions Of Populations In Space(2011-07) DeAngelis, Donald L.; Wolkowicz, Gail S. K.; Lou, Yuan; Jiang, Yuexin X.; Novak, Mark; Svanback, Richard; Araujo, Márcio S.; Jo, YoungSeung; Cleary, Erin A.; Jiang, Yuexin X.A key assumption of the ideal free distribution (IFD) is that there are no costs in moving between habitat patches. However, because many populations exhibit more or less continuous population movement between patches and traveling cost is a frequent factor, it is important to determine the effects of costs on expected population movement patterns and spatial distributions. We consider a food chain (tritrophic or bitrophic) in which one species moves between patches, with energy cost or mortality risk in movement. In the two-patch case, assuming forced movement in one direction, an evolutionarily stable strategy requires bidirectional movement, even if costs during movement are high. In the N-patch case, assuming that at least one patch is linked bidirectionally to all other patches, optimal movement rates can lead to source-sink dynamics where patches with negative growth rates are maintained by other patches with positive growth rates. As well, dispersal between patches is not balanced (even in the two-patch case), leading to a deviation from the IFD. Our results indicate that cost-associated forced movement can have important consequences for spatial metapopulation dynamics. Relevance to marine reserve design and the study of stream communities subject to drift is discussed.Item Superdiffusive trajectories in Brownian motion(2013-02) Duplat, Jerome; Kheifets, Simon; Li, Tongcang; Raizen, Mark G.; Villermaux, Emmanuel; Li, Tongcang; Raizen, Mark G.The Brownian motion of a microscopic particle in a fluid is one of the cornerstones of statistical physics and the paradigm of a random process. One of the most powerful tools to quantify it was provided by Langevin, who explicitly accounted for a short-time correlated "thermal" force. The Langevin picture predicts ballistic motion, < x(2)> similar to t(2) at short-time scales, and diffusive motion < x(2)> similar to t at long-time scales, where x is the displacement of the particle during time t, and the average is taken over the thermal distribution of initial conditions. The Langevin equation also predicts a superdiffusive regime, where < x(2)> similar to t(3), under the condition that the initial velocity is fixed rather than distributed thermally. We analyze the motion of an optically trapped particle in air and indeed find t(3) dispersion. This observation is a direct proof of the existence of the random, rapidly varying force imagined by Langevin. DOI: 10.1103/PhysRevE.87.020105