271 research outputs found

    Monte Carlo Simulation Calculation of Critical Coupling Constant for Continuum \phi^4_2

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    We perform a Monte Carlo simulation calculation of the critical coupling constant for the continuum {\lambda \over 4} \phi^4_2 theory. The critical coupling constant we obtain is [{\lambda \over \mu^2}]_crit=10.24(3).Comment: 11 pages, 4 figures, LaTe

    Influence of the Coriolis force in atom interferometry

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    In a light-pulse atom interferometer, we use a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation and to characterize configuration space wave packets. For interferometers with large momentum transfer and large pulse separation time, we improve the contrast by up to 350% and suppress systematic effects. We also reach what is to our knowledge the largest spacetime area enclosed in any atom interferometer to date. We discuss implications for future high performance instruments.Comment: 4 pages, 5 figures, 1 tabl

    Immunologic Investigations of T-Cell Regulation of Human IgE Antibody Secretion and Allergic Responses

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    The pathophysiology of allergic disease is multifactorial, involving an intricate network of interactions among cells, mediators, and cytokines. Substantial progress has been made in defining the role of antigen-specific T cells and cytokines in the regulation of immunoglobulin E (IgE) synthesis and the atopic diseases. The development of antigen-specific T-cell lines and clones has facilitated efforts to characterize human T-cell subsets and their cytokine repertoires. Molecular methods currently available include techniques for the quantitative analysis of cytokine gene expression and secretion from activated T cells ex vivo as well as in tissues. The availability of these newly developed techniques has become essential to the investigation of the pharmacologic regulation of T cells and cytokines both in vitro and in vivo. Future investigations will contribute to our understanding of the differential regulation of T-cell subsets and their relationships to allergic diseases, ultimately leading to a better understanding of the molecular pathogenesis of allergic diseases and the design of more effective therapeutic interventions

    Evaluation of Liquefaction Potential and Post-Liquefaction Settlement of Tzuoswei River Alluvial Plain in Western Taiwan

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    Taiwan is located in the conjunction area between Eurasia Plate and Philippine Sea Plate. As a result, the geology condition of the island is complex and the earthquake activity is frequent. On September 21, 1999, a severe earthquake (ML = 7.3) hit Chi-chi Town and resulted in significant damages and casualties in the mid-west plain of Taiwan. The alluvial deposits of Tzuoswei River, the largest river system of the island, had also experienced serious liquefaction damages during the shaking. The aim of the study was to as-sess the potential of liquefaction and the associated post-liquefaction settlement of the area. A total of about 1200 effective boreholes were collected. Three types of liquefaction analysis procedures were adopted, including Seed, Tokimatsu & Yoshimi, and the new version of Japanese Roadway Authority methods. A weighing technique suggested by Iwasaki was then used to evaluate the overall liquefaction potential. In addition, post-liquefaction settlements were estimated based on the procedures proposed by Ishihara. Con-tours of liquefaction potential and post-liquefaction settlement were also generated for the entire study area. Finally, results of the analyses were compared with the regional topography, geology, environmental factors, as well as the locations of critical projects in this area

    Chiral Vertex Operators in Off-Conformal Theory: The Sine-Gordon Example

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    We study chiral vertex operators in the sine-Gordon [SG] theory, viewed as an off-conformal system. We find that these operators, which would have been primary fields in the conformal limit, have interesting and, in some ways, unexpected properties in the SG model. Some of them continue to have scale- invariant dynamics even in the presence of the non-conformal cosine interaction. For instance, it is shown that the Mandelstam operator for the bosonic representation of the Fermi field does {\it not} develop a mass term in the SG theory, contrary to what the real Fermi field in the massive Thirring model is expected to do. It is also shown that in the presence of the non-conformal interactions, some vertex operators have unique Lorentz spins, while others do not.Comment: 32 pages, Univ. of Illinois Preprint # ILL-(TH)-93-1

    Gravitational Redshift, Equivalence Principle, and Matter Waves

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    We review matter wave and clock comparison tests of the gravitational redshift. To elucidate their relationship to tests of the universality of free fall (UFF), we define scenarios wherein redshift violations are coupled to violations of UFF ("type II"), or independent of UFF violations ("type III"), respectively. Clock comparisons and atom interferometers are sensitive to similar effects in type II and precisely the same effects in type III scenarios, although type III violations remain poorly constrained. Finally, we describe the "Geodesic Explorer," a conceptual spaceborne atom interferometer that will test the gravitational redshift with an accuracy 5 orders of magnitude better than current terrestrial redshift experiments for type II scenarios and 12 orders of magnitude better for type III.Comment: Work in progress. 11 page

    Cysteine oxidation targets peroxiredoxins 1 and 2 for exosomal release through a novel mechanism of redox-dependent secretion

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    Non-classical protein secretion is of major importance as a number of cytokines and inflammatory mediators are secreted via this route. Current evidence indicates that there are several mechanistically distinct methods of non-classical secretion. We have recently shown that peroxiredoxin (Prdx) 1 and Prdx2 are released by various cells upon exposure to inflammatory stimuli such as LPS or TNF-α. The released Prdx then acts to induce production of inflammatory cytokines. However, Prdx1 and 2 do not have signal peptides and therefore must be secreted by alternative mechanisms as has been postulated for the inflammatory mediators IL-1β and HMGB1. We show here that circulating Prdx1 and 2 are present exclusively as disulphide-linked homodimers. Inflammatory stimuli also induce in vitro release of Prdx1 and 2 as disulfide-linked homodimers. Mutation of cysteines Cys51 or Cys172 (but not Cys70) in Prdx2, and Cys52 or Cys173 (but not Cys71 or Cys83) in Prdx1 prevented dimer formation and this was associated with inhibition of their TNF-α-induced release. Thus, the presence and oxidation of key cysteine residues in these proteins are a prerequisite for their secretion in response to TNF-α and this release can be induced with an oxidant. In contrast, the secretion of the nuclear-associated danger signal HMGB1 is independent of cysteine oxidation, as shown by experiments with a cysteine-free HMGB1 mutant. Release of Prdx1 and 2 is not prevented by inhibitors of the classical secretory pathway; instead, both Prdx1 and 2 are released in exosomes from both HEK cells and monocytic cells. Serum Prdx1 and 2 are also associated with the exosomes. These results describe a novel pathway of protein secretion mediated by cysteine oxidation that underlines the importance of redox-dependent signalling mechanisms in inflammation

    Mortality of wild golden grey mullet (Liza auratus) in Iranian waters of the Caspian Sea, associated with viral nervous necrosis-like agent

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    An acute mortality caused by an uncertain agent occurred in wild golden grey mullet (Liza auratus) population in the Iranian side of the Caspian Sea in February, 2004. Clinical signs of the moribund fish were erratic behavior such as spiral swimming, belly-up at rest and over inflation of swim bladder. Histological examination of brain of dead fish revealed hyperaemia, degeneration and necrosis in external granular layers as well as focal extension in intestine. Severe leucopenia was also observed. No putative causal factors were suggested by bacteriological, parasitological or environmental examinations. In virological examinations, however brains of affected golden grey mullet were positive in the reverse transcriptase-polymerase chain reaction test for piscine nodavirus (Nodaviridae, Betanodavirus), the causative agent of Encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN) in a variety of cultured marine fishes worldwide. Nucleotide sequence of the PCR amplicons is closely related with the coat protein gene of piscine nodaviruses, particularly red spotted grouper nervous necrosis virus (RGNNV). Although, it was not succeeded to isolate the virus, experimental infection with the brain homogenates of the affected fish in sevenband grouper (Epinephelus septemfasciatus), which is highly susceptible to RGNNV, produced neurological abnormality followed by mortality. These results suggest that the mortality observed in golden grey mullet in the Caspian Sea might have been associated with piscine nodavirus infection
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