1,916 research outputs found

    Effects of DDT on the Density and Diversity of Tardigrades

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    Twenty lichen-bearing tree bark samples were collected from DDT sprayed American elm trees (Ulmus Americana L.) in central Iowa. Twenty comparable samples were collected from an adjacent nontreated habitat. A tardigrade density of 4 individuals collected from the treated habitat was found to differ significantly (P \u3c .01) from a density of 97 individuals collected from the non-treated area. Margalef\u27s diversity index (D=S-1/1n N) determinations were found to be 0.00 and 0.44 for the treated and non-treated habitats, respectively. Tardigrade species organization within the nontreated habitat did not differ significantly from that as predicted by MacArthur\u27s broken-stick model, suggesting that tardigrade species occupy contiguous, non-overlapping niches within a lichen-bearing tree bark ecosystem. It is suggested that measurements depicting microfauna-lichen-tree bark relationships might serve as useful criteria in evaluating pesticide stress effects on total forest ecosystems

    Josephson Coupling through a Quantum Dot

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    We derive, via fourth order perturbation theory, an expression for the Josephson current through a gated interacting quantum dot. We analyze our expression for two different models of the superconductor-dot-superconductor (SDS) system. When the matrix elements connecting dot and leads are featureless constants, we compute the Josephson coupling J_c as a function of the gate voltage and Coulomb interaction. In the diffusive dot limit, we compute the probability distribution P(J_c) of Josephson couplings. In both cases, pi junction behavior (J_c < 0) is possible, and is not simply dependent on the parity of the dot occupancy.Comment: 9 pages; 3 encapsulated PostScript figure

    An analysis of integrative outcomes in the Dayton peace negotiations

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    The nature of the negotiated outcomes of the eight issues of the Dayton Peace Agreement was studied in terms of their integrative and distributive aspects. in cases where integrative elements were Sound, further analysis was conducted by concentrating on Pruitt's five types of integrative solutions: expanding the pie, cost cutting, non-specific compensation, logrolling, and bridging. The results showed that real world international negotiations can arrive at integrative agreements even when they involve redistribution of resources tin this case the redistribution of former Yugoslavia). Another conclusion was that an agreement can consist of several distributive outcomes and several integrative outcomes produced by different kinds of mechanisms. Similarly, in single issues more than one mechanism can be used simultaneously. Some distributive bargaining was needed in order to determine how much compensation was required. Finally, each integrative formula had some distributive aspects as well

    Random tree growth by vertex splitting

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    We study a model of growing planar tree graphs where in each time step we separate the tree into two components by splitting a vertex and then connect the two pieces by inserting a new link between the daughter vertices. This model generalises the preferential attachment model and Ford's α\alpha-model for phylogenetic trees. We develop a mean field theory for the vertex degree distribution, prove that the mean field theory is exact in some special cases and check that it agrees with numerical simulations in general. We calculate various correlation functions and show that the intrinsic Hausdorff dimension can vary from one to infinity, depending on the parameters of the model.Comment: 47 page

    Clubbing masculinities: Gender shifts in gay men's dance floor choreographies

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    This is an Author's Accepted Manuscript of an article published in Journal of Homosexuality, 58(5), 608-625, 2011 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/10.1080/00918369.2011.563660This article adopts an interdisciplinary approach to understanding the intersections of gender, sexuality, and dance. It examines the expressions of sexuality among gay males through culturally popular forms of club dancing. Drawing on political and musical history, I outline an account of how gay men's gendered choreographies changed throughout the 1970s, 80s, and 90s. Through a notion of “technologies of the body,” I situate these developments in relation to cultural levels of homophobia, exploring how masculine expressions are entangled with and regulated by musical structures. My driving hypothesis is that as perceptions of cultural homophobia decrease, popular choreographies of gay men's dance have become more feminine in expression. Exploring this idea in the context of the first decade of the new millennium, I present a case study of TigerHeat, one of the largest weekly gay dance club events in the United States

    Between overt and covert research: concealment and disclosure in an ethnographic study of commercial hospitality

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    This article examines the ways in which problems of concealment emerged in an ethnographic study of a suburban bar and considers how disclosure of the research aims, the recruitment of informants, and elicitation of information was negotiated throughout the fieldwork. The case study demonstrates how the social context and the relationships with specific informants determined overtness or covertness in the research. It is argued that the existing literature on covert research and covert methods provides an inappropriate frame of reference with which to understand concealment in fieldwork. The article illustrates why concealment is sometimes necessary, and often unavoidable, and concludes that the criticisms leveled against covert methods should not stop the fieldworker from engaging in research that involves covertness

    Many Body Theory of Charge Transfer in Hyperthermal Atomic Scattering

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    We use the Newns-Anderson Hamiltonian to describe many-body electronic processes that occur when hyperthermal alkali atoms scatter off metallic surfaces. Following Brako and Newns, we expand the electronic many-body wavefunction in the number of particle-hole pairs (we keep terms up to and including a single particle-hole pair). We extend their earlier work by including level crossings, excited neutrals and negative ions. The full set of equations of motion are integrated numerically, without further approximations, to obtain the many-body amplitudes as a function of time. The velocity and work-function dependence of final state quantities such as the distribution of ion charges and excited atomic occupancies are compared with experiment. In particular, experiments that scatter alkali ions off clean Cu(001) surfaces in the energy range 5 to 1600 eV constrain the theory quantitatively. The neutralization probability of Na+^+ ions shows a minimum at intermediate velocity in agreement with the theory. This behavior contrasts with that of K+^+, which shows ... (7 figures, not included. Figure requests: [email protected])Comment: 43 pages, plain TeX, BUP-JBM-

    Adam Sandler as (questionable) masculine ‘role model’: towards an analysis of disgust and violence in Adam Sandler's comedian comedy

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    © 2018 Informa UK Limited, trading as Taylor & Francis Group Adam Sandler's film work has been critically vilified and paid little attention by academics. This article suggests that his work justifies sustained academic attention, yet I conclude that he offers questionable masculine role models dependent on masculinity being asserted via ambivalent dis-identification with gay men and women. I argue this case via critique of the most sustained analyses of his workand via close readings of aspects of Sandler's films. I dispute Chapman's contextualisation of Sandler's film comedies in relation to thinking about masculinity and gay men. These changes have arisen in response to feminism and the lesbian and gay movement. I argue that Chapman's contextualisation of, and the ambiguities of Sandler's engagement with, feminism and gay men needs more critical attention. Further, I argue that we should actively read Sandler's films using Seidman's idea of comedian comedy and that focusing attention on such comedies’ tensions with narrative film enable us to direct our critical attention on the ambivalences present in Sandler's movies. His films show resistance to relinquishing some privileges of dominant forms of masculinity (physical violence) and demonstrate disgust withthe sexuality, bodies and behaviour of gay men

    Understanding Dwarf Galaxies in order to Understand Dark Matter

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    Much progress has been made in recent years by the galaxy simulation community in making realistic galaxies, mostly by more accurately capturing the effects of baryons on the structural evolution of dark matter halos at high resolutions. This progress has altered theoretical expectations for galaxy evolution within a Cold Dark Matter (CDM) model, reconciling many earlier discrepancies between theory and observations. Despite this reconciliation, CDM may not be an accurate model for our Universe. Much more work must be done to understand the predictions for galaxy formation within alternative dark matter models.Comment: Refereed contribution to the Proceedings of the Simons Symposium on Illuminating Dark Matter, to be published by Springe
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