243 research outputs found

    Hertz potentials approach to the dynamical Casimir effect in cylindrical cavities of arbitrary section

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    We study the creation of photons in resonant cylindrical cavities with time dependent length. The physical degrees of freedom of the electromagnetic field are described using Hertz potentials. We describe the general formalism for cavities with arbitrary section. Then we compute explicitly the number of TE and TM motion-induced photons for cylindrical cavities with rectangular and circular sections. We also discuss the creation of TEM photons in non-simply connected cylindrical cavities.Comment: 13 pages, 3 figures, revtex

    Inflammation, organomegaly, and muscle wasting despite hyperphagia in a mouse model of burn cachexia.

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    BACKGROUND: Burn injury results in a chronic inflammatory, hypermetabolic, and hypercatabolic state persisting long after initial injury and wound healing. Burn survivors experience a profound and prolonged loss of lean body mass, fat mass, and bone mineral density, associated with significant morbidity and reduced quality of life. Understanding the mechanisms responsible is essential for developing therapies. A complete characterization of the pathophysiology of burn cachexia in a reproducible mouse model was lacking. METHODS: Young adult (12-16 weeks of age) male C57BL/6J mice were given full thickness burns using heated brass plates or sham injury. Food and water intake, organ and muscle weights, and muscle fiber diameters were measured. Body composition was determined by Piximus. Plasma analyte levels were determined by bead array assay. RESULTS: Survival and weight loss were dependent upon burn size. The body weight nadir in burned mice was 14 days, at which time we observed reductions in total body mass, lean carcass mass, individual muscle weights, and muscle fiber cross-sectional area. Muscle loss was associated with increased expression of the muscle ubiquitin ligase, MuRF1. Burned mice also exhibited reduced fat mass and bone mineral density, concomitant with increased liver, spleen, and heart mass. Recovery of initial body weight occurred at 35 days; however, burned mice exhibited hyperphagia and polydipsia out to 80 days. Burned mice had significant increases in serum cytokine, chemokine, and acute phase proteins, consistent with findings in human burn subjects. CONCLUSIONS: This study describes a mouse model that largely mimics human pathophysiology following severe burn injury. These baseline data provide a framework for mouse-based pharmacological and genetic investigation of burn-injury-associated cachexia

    Diagnosis and Management of Esophageal Injuries: A Western Trauma Association Critical Decisions Algorithm

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    ABSTRACT: This is a recommended management algorithm from the Western Trauma Association addressing the diagnostic evaluation and management of esophageal injuries in adult patients. Because there is a paucity of published prospective randomized clinical trials that have generated Class I data, the recommendations herein are based primarily on published observational studies and expert opinion of Western Trauma Association members. The algorithms and accompanying comments represent a safe and sensible approach that can be followed at most trauma centers. We recognize that there will be patient, personnel, institutional, and situational factors that may warrant or require deviation from the recommended algorithm. We encourage institutions to use this guideline to formulate their own local protocols. The algorithm contains letters at decision points; the corresponding paragraphs in the text elaborate on the thought process and cite pertinent literature. The annotated algorithm is intended to (a) serve as a quick bedside reference for clinicians; (b) foster more detailed patient care protocols that will allow for prospective data collection and analysis to identify best practices; and (c) generate research projects to answer specific questions concerning decision making in the management of adults with esophageal injuries

    Linear canonical transformations and quantum phase:a unified canonical and algebraic approach

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    The algebra of generalized linear quantum canonical transformations is examined in the prespective of Schwinger's unitary-canonical basis. Formulation of the quantum phase problem within the theory of quantum canonical transformations and in particular with the generalized quantum action-angle phase space formalism is established and it is shown that the conceptual foundation of the quantum phase problem lies within the algebraic properties of the quantum canonical transformations in the quantum phase space. The representations of the Wigner function in the generalized action-angle unitary operator pair for certain Hamiltonian systems with the dynamical symmetry are examined. This generalized canonical formalism is applied to the quantum harmonic oscillator to examine the properties of the unitary quantum phase operator as well as the action-angle Wigner function.Comment: 19 pages, no figure

    The recent shift in early summer Arctic atmospheric circulation

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    1 The last six years (2007-2012) show a persistent change in early summer Arctic wind patterns relative to previous decades. The persistent pattern, which has been previously recognized as the Arctic Dipole (AD), is characterized by relatively low sea-level pressure over the Siberian Arctic with high pressure over the Beaufort Sea, extending across northern North America and over Greenland. Pressure differences peak in June. In a search for a proximate cause for the newly persistent AD pattern, we note that the composite 700 hPa geopotential height field during June 2007-2012 exhibits a positive anomaly only on the North American side of the Arctic, thus creating the enhanced mean meridional flow across the Arctic. Coupled impacts of the new persistent pattern are increased sea ice loss in summer, long-lived positive temperature anomalies and ice sheet loss in west Greenland, and a possible increase in Arctic-subarctic weather linkages through higheramplitude upper-level flow. The North American location of increased 700 hPa positive anomalies suggests that a regional atmospheric blocking mechanism is responsible for the presence of the AD pattern, consistent with observations of unprecedented high pressure anomalies over Greenland since 2007. ©2012. American Geophysical Union. All Rights Reserved

    Ethnicity and sexuality

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    This paper explores the connections between ethnicity and sexuality. Racial, ethnic, and national boundaries are also sexual boundaries. The borderlands dividing racial, ethnic, and national identities and communities constitute ethnosexual frontiers, erotic intersections that are heavily patrolled, policed, and protected, yet regularly are penetrated by individuals forging sexual links with ethnic "others." Normative heterosexuality is a central component of racial, ethnic, and nationalist ideologies; both adherence to and deviation from approved sexual identities and behaviors define and reinforce racial, ethnic, and nationalist regimes. To illustrate the ethnicity/sexuality nexus and to show the utility of revealing this intimate bond for understanding ethnic relations, I review constructionist models of ethnicity and sexuality in the social sciences and humanities, and I discuss ethnosexual boundary processes in several historical and contemporary settings: the sexual policing of nationalism, sexual aspects of US-American Indian relations, and the sexualization of the black-white color line

    I moder ni processi fotomeccanici

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