18,472 research outputs found

    Extended Conformal Symmetry in d4d\neq 4: Conformal Symmetry of Abelian Gauge Theory in the Physical Sector

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    Abelian gauge theory in d4d\neq 4 spacetime dimensions is an example of a scale invariant theory which does not possess conformal symmetry -- the special conformal transformation(SCT) explicitly breaks the gauge invariance of the theory. In this work, we construct a non-local gauge-invariant extension of the SCT, which is compatible with the BRST formalism and defines a new symmetry of the physical Hilbert space of the Maxwell theory for any dimension d3d\geqslant 3. We prove the invariance of the Maxwell theory in d3d\geqslant 3 by explicitly showing that the gauge-invariant two-point correlation functions, the action, and the classical equation of motion are unchanged under such a transformation.Comment: 23 page

    Rigorous constraints on the matrix elements of the energy-momentum tensor

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    The structure of the matrix elements of the energy-momentum tensor play an important role in determining the properties of the form factors A(q2)A(q^{2}), B(q2)B(q^{2}) and C(q2)C(q^{2}) which appear in the Lorentz covariant decomposition of the matrix elements. In this paper we apply a rigorous frame-independent distributional-matching approach to the matrix elements of the Poincar\'{e} generators in order to derive constraints on these form factors as q0q \rightarrow 0. In contrast to the literature, we explicitly demonstrate that the vanishing of the anomalous gravitomagnetic moment B(0)B(0) and the condition A(0)=1A(0)=1 are independent of one another, and that these constraints are not related to the specific properties or conservation of the individual Poincar\'{e} generators themselves, but are in fact a consequence of the physical on-shell requirement of the states in the matrix elements and the manner in which these states transform under Poincar\'{e} transformations.Comment: 11 pages; v2: additional comments added, matches published versio

    Patellar Tendon Morphology in Trans-tibial Amputees Utilizing a Prosthesis with a Patellar-tendon- Bearing Feature

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    A patellar-tendon-bearing (PTB) bar is a common design feature used in the socket of trans-tibial prostheses to place load on the pressure-tolerant tissue. As the patellar tendon in the residual limb is subjected to the perpendicular compressive force not commonly experienced in normal tendons, it is possible for tendon degeneration to occur over time. The purpose of this study was to compare patellar tendon morphology and neovascularity between the residual and intact limbs in trans-tibial amputees and healthy controls. Fifteen unilateral trans-tibial amputees who utilized a prosthesis with a PTB feature and 15 age- and sex- matched controls participated. Sonography was performed at the proximal, mid-, and distal portions of each patellar tendon. One-way ANOVAs were conducted to compare thickness and collagen fber organization and a chi-square analysis was used to compare the presence of neovascularity between the three tendon groups. Compared to healthy controls, both tendons in the amputees exhibited increased thickness at the mid- and distal portions and a higher degree of collagen fber disorganization. Furthermore, neovascularity was more common in the tendon of the residual limb. Our results suggest that the use of a prosthesis with a PTB feature contributes to morphological changes in bilateral patellar tendons

    Building Momentum to Sustain Social Change Evaluation of the of Katrina Women's Response Fund

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    In the time that has passed since powerful hurricanes decimated the Gulf Coast region in 2005, the recovery and rebuilding process continues to expose the deep vulnerabilities of a society that has not effectively addressed the legacy of racism. In response to the injustices, human suffering, destruction, and massive displacement caused by Hurricanes Katrina and Rita, the Ms. Foundation for Women, WFN and its partner funds, with the $1.3 million support of the W.K. Kellogg Foundation, continued to strengthen the Katrina Women's Response Fund (KWRF)

    Influence of blade aerodynamic model on prediction of helicopter rotor aeroacoustic signatures

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    Brown’s vorticity transport model has been used to investigate how the local blade aerodynamic model influences the quality of the prediction of the high-frequency airloads associated with blade–vortex interactions, and thus the accuracy with which the acoustic signature of a helicopter rotor can be predicted. The vorticity transport model can accurately resolve the structure of the wake of the rotor and allows significant flexibility in the way that the blade loading can be represented. The Second Higher-Harmonic Control Aeroacoustics Rotor Test was initiated to provide experimental insight into the acoustic signature of a rotor in cases of strong blade–vortex interaction. Predictions of two models for the local blade aerodynamics are compared with the test data. A marked improvement in accuracy of the predicted high-frequency airloads and acoustic signature is obtained when a lifting-chord model for the blade aerodynamics is used instead of a lifting-line-type approach. Errors in the amplitude and phase of the acoustic peaks are reduced, and the quality of the prediction is affected to a lesser extent by the computational resolution of the wake, with the lifting-chord model producing the best representation of the distribution of sound pressure below the rotor

    Quenching of Spin Hall Effect in Ballistic nano-junctions

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    We show that a nanometric four-probe ballistic junction can be used to check the presence of a transverse spin Hall current in a system with a Spin Orbit coupling not of the Rashba type, but rather due to the in-plane electric field. Indeed, the spin Hall effect is due to the presence of an effective small transverse magnetic field corresponding to the Spin Orbit coupling generated by the confining potential. The strength of the field and the junction shape characterize the quenching Hall regime, usually studied by applying semi-classical approaches. We discuss how a quantum mechanical relativistic effect, such as the Spin Orbit one, can be observed in a low energy system and explained by using classical mechanics techniques.Comment: 5 pages, 4 figures, PACS: 72.25.-b, 72.20.My, 73.50.Jt, to appear in Phys. Rev.

    Integer Spin Hall Effect in Ballistic Quantum Wires

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    We investigate the ballistic electron transport in a two dimensional Quantum Wire under the action of an electric field (EyE_y). We demonstrate how the presence of a Spin Orbit coupling, due to the uniform electric confinement field gives a non-commutative effect as in the presence of a transverse magnetic field. We discuss how the non commutation implies an edge localization of the currents depending on the electron spins also giving a semi-classical spin dependent Hall current. We also discuss how it is possible obtain a quantized Spin Hall conductance in the ballistic transport regime by developing the Landauer formalism and show the coupling between the spin magnetic momentum and the orbital one due to the presence of a circulating current.Comment: 7 pages, 5 figures, accepted for publication in Phys. Rev. B, PACS: 72.25.-b, 72.10.-d, 72.15.Rn, 73.23.-b, 71.10.P

    Application of value management in project briefing

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    Author name used in this publication: Qiping Shen2004-2005 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
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