12,142 research outputs found

    Home Ranges and Movements of Adult Deer on Fort Chaffee, Arkansas

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    We radio-tracked 27 white-tailed deer (Odocoileus virginianus) weekly for one year on Fort Chaffee, Arkansas, to investigate their seasonal home ranges and movements between hunted areas and refuges on this military base. This work resulted in2,123 separate radiolocations, of which 85% (1,799) were suitable for use in home range analyses. We used the McPAAL computer package to estimate home range using the Harmonic Mean and minimum convex polygon (MCP) methods. Harmonic mean estimates were based on 95% contour lines. Home range size differed between the sexes and methods. Male home ranges were larger than those of females (t= 3.32, P\u3c0.01; harmonic mean) (t=2.07, P\u3c0.05; MCP). Average home range sizes for males and females based on the harmonic mean method were estimated to be 483 ha and 181 ha, respectively, whereas home range estimates for males and females using the MCP method were 636 ha and 289 ha, respectively. The average home range size for all deer was 259 ha (harmonic mean) and 379 ha (MCP). We found no evidence that females restricted their home ranges during the fawning period. However, females\u27 home ranges expanded during the breeding season, perhaps to find mates. Few deer moved to refuge areas that were off-limits to hunters during the hunting season

    Mortality of Adult White-Tailed Deer on Fort Chaffee, Arkansas

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    We conducted a telemetry study on Fort Chaffee, Arkansas, to estimate the extent, timing, and causes of mortality among resident adult white-tailed deer {Odocoileus virginianus). Twenty-seven deer were captured, radio-collared and monitored for 1 yr to assess seasonal mortality. Annual mortality rates differed considerably between sexes, with males exhibiting a much higher rate (86.1%) than females (5.3%). The primary causes of death among males were poaching, predation by coyotes, and legal harvest. Legal harvest by a gun-hunter accounted for the only female mortality. No mortalities were attributed to military exercises, which occurred frequently on the study area. Our results suggest that the male segment of the population would benefit from increased enforcement efforts to reduce illegal harvests and that continued liberal harvest of the female segment is advisable to maintain a balanced population sex ratio

    Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions

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    We have measured the running coupling constant of SU(3) gauge theory coupled to Nf=2 flavors of symmetric representation fermions, using the Schrodinger functional scheme. Our lattice action is defined with hypercubic smeared links which, along with the larger lattice sizes, bring us closer to the continuum limit than in our previous study. We observe that the coupling runs more slowly than predicted by asymptotic freedom, but we are unable to observe fixed point behavior before encountering a first order transition to a strong coupling phase. This indicates that the infrared fixed point found with the thin-link action is a lattice artifact. The slow running of the gauge coupling permits an accurate determination of the mass anomalous dimension for this theory, which we observe to be small, gamma_m < 0.6, over the range of couplings we can reach. We also study the bulk and finite-temperature phase transitions in the strong coupling region.Comment: 17 pages, 16 figures. Substantial modifications to explain why the fat-link result for the beta function supersedes our thin-link result; also updated the phase diagram to reflect additional numerical work. Added references. Final versio

    Importance of Tests for the Complete Lorentz Structure of the t --> W+ b vertex at Hadron Colliders

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    The most general Lorentz-invariant decay-density-matrix for tW+b(l+ν)bt\to W^{+}b\to (l^{+}\nu)b, or for tW+b(jdˉju)bt\to W^{+}b\to (j_{\bar d}j_u)b, is expressed in terms of eight helicity parameters. The parameters are physically defined in terms of partial-width-intensities for polarized-final-states in tW+bt\to W^{+}b decay. The parameters are the partial width, the bb quark's chirality parameter ξ\xi, the W+W^+ polarimetry parameter σ\sigma, a "pre-SSB" test parameter ζ\zeta, and four WLW_{L}-WTW_{T} interference parameters η\eta, η\eta^{'}, ω\omega, ω\omega^{'} which test for T~FS\tilde T_{FS} violation. They can be used to test for non-CKM-type CP violation, anomalous ΓL,T\Gamma_{L,T}'s, top weak magnetism, weak electricity, and second-class currents. By stage-two spin-correlation techniques, percent level statistical uncertainites are typical for measurements at the Tevatron, and several mill level uncertainites are typical at the LHC.Comment: Minor clarifications. Expression for r_{+-} corrected. 19 pages LaTex + Tables + 1 Figur

    Analyzing and improving throughput of Automated Storage and Retrieval Systems in personal computer manufacturing

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    Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2005.Includes bibliographical references (leaf 85).The content of this thesis draws heavily on work completed during a 6.5 month MIT Leaders for Manufacturing (LFM) internship at Dell Corporation's personal computer manufacturing facility in Lebanon, Tennessee (EG1) from June 2004 to December 2004. This work relates primarily to efforts to analyze and improve the throughput of the Automated Storage and Retrieval System (ASRS) in that factory. Wherever possible, the thesis abstracts from the EG1 factory case study to provide lessons for improving the throughput of ASRSs and accumulative manufacturing systems in general. In addition to this core of the thesis, specific implementation challenges encountered during the EG 1 case study are addressed. Finally, general cultural observations about Dell's manufacturing environment are discussed. The author believes the two most unique aspects of this work are the Crane Frontier framework developed for analyzing ASRS throughput (Section 2.6) and the range and taxonomy of ASRS throughput improvement solutions (Chapter 3).by G. Thomas Heaps-Nelson.S.M.M.B.A

    Rigid Chiral Membranes

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    Statistical ensembles of flexible two-dimensional fluid membranes arise naturally in the description of many physical systems. Typically one encounters such systems in a regime of low tension but high stiffness against bending, which is just the opposite of the regime described by the Polyakov string. We study a class of couplings between membrane shape and in-plane order which break 3-space parity invariance. Remarkably there is only {\it one} such allowed coupling (up to boundary terms); this term will be present for any lipid bilayer composed of tilted chiral molecules. We calculate the renormalization-group behavior of this relevant coupling in a simplified model and show how thermal fluctuations effectively reduce it in the infrared.Comment: 11 pages, UPR-518T (This replaced version has fonts not used removed.

    The Minimal Moose for a Little Higgs

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    Recently a new class of theories of electroweak symmetry breaking have been constructed. These models, based on deconstruction and the physics of theory space, provide the first alternative to weak-scale supersymmetry with naturally light Higgs fields and perturbative new physics at the TeV scale. The Higgs is light because it is a pseudo-Goldstone boson, and the quadratically divergent contributions to the Higgs mass are cancelled by new TeV scale ``partners'' of the {\em same} statistics. In this paper we present the minimal theory space model of electroweak symmetry breaking, with two sites and four link fields, and the minimal set of fermions. There are very few parameters and degrees of freedom beyond the Standard Model. Below a TeV, we have the Standard Model with two light Higgs doublets, and an additional complex scalar weak triplet and singlet. At the TeV scale, the new particles that cancel the 1-loop quadratic divergences in the Higgs mass are revealed. The entire Higgs potential needed for electroweak symmetry breaking--the quartic couplings as well as the familiar negative mass squared--can be generated by the top Yukawa coupling, providing a novel link between the physics of flavor and electroweak symmetry breaking.Comment: 15 pages. References added. Included clarifying comments on the origin of quartic couplings, and on power-counting. More elegant model for generating Higgs potential from top Yukawa coupling presente

    Steric repulsion and van der Waals attraction between flux lines in disordered high Tc superconductors

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    We show that in anisotropic or layered superconductors impurities induce a van der Waals attraction between flux lines. This attraction together with the disorder induced repulsion may change the low B - low T phase diagram significantly from that of the pure thermal case considered recently by Blatter and Geshkenbein [Phys. Rev. Lett. 77, 4958 (1996)].Comment: Latex, 4 pages, 1 figure (Phys. Rev. Lett. 79, 139 (1997)
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