18,472 research outputs found
Extended Conformal Symmetry in : Conformal Symmetry of Abelian Gauge Theory in the Physical Sector
Abelian gauge theory in 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 . We prove the invariance of the Maxwell theory in 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
The structure of the matrix elements of the energy-momentum tensor play an
important role in determining the properties of the form factors ,
and 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 . In contrast to the literature, we explicitly demonstrate that
the vanishing of the anomalous gravitomagnetic moment and the condition
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
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
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
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
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
We investigate the ballistic electron transport in a two dimensional Quantum
Wire under the action of an electric field (). 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
Author name used in this publication: Qiping Shen2004-2005 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
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