2,989 research outputs found

    Notch filter

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    A notch filter for the selective attenuation of a narrow band of frequencies out of a larger band was developed. A helical resonator is connected to an input circuit and an output circuit through discrete and equal capacitors, and a resistor is connected between the input and the output circuits

    System for the measurement of ultra-low stray light levels

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    An apparatus is described for measuring the effectiveness of stray light suppression light shields and baffle arrangements used in optical space experiments and large space telescopes. The light shield and baffle arrangement and a telescope model are contained in a vacuum chamber. A source of short, high-powered light energy illuminates portions of the light shield and baffle arrangement and reflects a portion of same to a photomultiplier tube by virtue of multipath scattering. The resulting signal is transferred to time-channel electronics timed by the firing of the high energy light source allowing time discrimination of the signal thereby enabling the light scattered and suppressed by the model to be distinguished from the walls and holders around the apparatus

    Mycobacterium sp. as a possible cause of hypersensitivity pneumonitis in machine workers.

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    Hypersensitivity pneumonitis (HP) in workers exposed to metal removal fluids (MRFs) is increasing. This study supports the hypothesis that aerosolized mycobacteria colonizing the MRFs likely cause the disease. Three case studies of HP outbreaks among metal workers showed potentially high exposures to a rare and newly proposed Mycobacterium species. Retrospective review of samples submitted to our laboratory showed an association between presence of mycobacteria and HP

    An Effective Theory for Midgap States in Doped Spin Ladder and Spin-Peierls Systems: Liouville Quantum Mechanics

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    In gapped spin ladder and spin-Peierls systems the introduction of disorder, for example by doping, leads to the appearance of low energy midgap states. The fact that these strongly correlated systems can be mapped onto one dimensional noninteracting fermions provides a rare opportunity to explore systems which have both strong interactions and disorder. In this paper we show that the statistics of the zero energy midgap wave functions in these models can be effectively described by Liouville Quantum Mechanics. This enables us to calculate the disorder averaged N-point correlation functions of these states (the explicit calculation is performed for N=2,3). We find that whilst these midgap states are typically weakly correlated, their disorder averaged correlation are power law. This discrepancy arises because the correlations are not self-averaging and averages of the wave functions are dominated by anomalously strongly correlated configurations.Comment: 13 page latex fil

    Validation of an ICD code for accurately identifying emergency department patients who suffer an out-of-hospital cardiac arrest.

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    AIM: International classification of disease (ICD-9) code 427.5 (cardiac arrest) is utilized to identify cohorts of patients who suffer out-of-hospital cardiac arrest (OHCA), though the use of ICD codes for this purpose has never been formally validated. We sought to validate the utility of ICD-9 code 427.5 by identifying patients admitted from the emergency department (ED) after OHCA. METHODS: Adult visits to a single ED between January 2007 and July 2012 were retrospectively examined and a keyword search of the electronic medical record (EMR) was used to identify patients. Cardiac arrest was confirmed; and ICD-9 information and location of return of spontaneous circulation (ROSC) were collected. Separately, the EMR was searched for patients who received ICD-9 code 427.5. The kappa coefficient (κ) was calculated, as was the sensitivity and specificity of the code for identifying OHCA. RESULTS: The keyword search identified 1717 patients, of which 385 suffered OHCA and 333 were assigned the code 427.5. The agreement between ICD-9 code and cardiac arrest was excellent (κ = 0.895). The ICD-9 code 427.5 was both specific (99.4%) and sensitive (86.5%). Of the 52 cardiac arrests that were not identified by ICD-9 code, 33% had ROSC before arrival to the ED. When searching independently on ICD-9 code, 347 patients with ICD-9 code 427.5 were found, of which 320 were true arrests. This yielded a positive predictive value of 92% for ICD-9 code 427.5 in predicting OHCA. CONCLUSIONS: ICD-9 code 427.5 is sensitive and specific for identifying ED patients who suffer OHCA with a positive predictive value of 92%

    D-Terms from Generalized NS-NS Fluxes in Type II

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    Orientifolds of type II string theory admit a certain set of generalized NS-NS fluxes, including not only the three-form field strength H, but also metric and non-geometric fluxes, which are related to H by T-duality. We describe in general how these fluxes appear as parameters of an effective N=1 supergravity theory in four dimensions, and in particular how certain generalized NS-NS fluxes can act as charges for R-R axions, leading to D-term contributions to the effective scalar potential. We illustrate these phenomena in type IIB with the example of a certain orientifold of T^6/Z_4.Comment: 31+1 pages, uses utarticle.cls; v2: references adde

    Non-geometric flux vacua, S-duality and algebraic geometry

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    The four dimensional gauged supergravities descending from non-geometric string compactifications involve a wide class of flux objects which are needed to make the theory invariant under duality transformations at the effective level. Additionally, complex algebraic conditions involving these fluxes arise from Bianchi identities and tadpole cancellations in the effective theory. In this work we study a simple T and S-duality invariant gauged supergravity, that of a type IIB string compactified on a T6/(Z2xZ2)T^6/(Z_2 x Z_2) orientifold with O3/O7-planes. We build upon the results of recent works and develop a systematic method for solving all the flux constraints based on the algebra structure underlying the fluxes. Starting with the T-duality invariant supergravity, we find that the fluxes needed to restore S-duality can be simply implemented as linear deformations of the gauge subalgebra by an element of its second cohomology class. Algebraic geometry techniques are extensively used to solve these constraints and supersymmetric vacua, centering our attention on Minkowski solutions, become systematically computable and are also provided to clarify the methods.Comment: 47 pages, 10 tables, typos corrected, Accepted for Publication in Journal of High Energy Physic

    High definition systems in Japan

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    The successful implementation of a strategy to produce high-definition systems within the Japanese economy will favorably affect the fundamental competitiveness of Japan relative to the rest of the world. The development of an infrastructure necessary to support high-definition products and systems in that country involves major commitments of engineering resources, plants and equipment, educational programs and funding. The results of these efforts appear to affect virtually every aspect of the Japanese industrial complex. The results of assessments of the current progress of Japan toward the development of high-definition products and systems are presented. The assessments are based on the findings of a panel of U.S. experts made up of individuals from U.S. academia and industry, and derived from a study of the Japanese literature combined with visits to the primary relevant industrial laboratories and development agencies in Japan. Specific coverage includes an evaluation of progress in R&D for high-definition television (HDTV) displays that are evolving in Japan; high-definition standards and equipment development; Japanese intentions for the use of HDTV; economic evaluation of Japan's public policy initiatives in support of high-definition systems; management analysis of Japan's strategy of leverage with respect to high-definition products and systems

    Random-mass Dirac fermions in an imaginary vector potential: Delocalization transition and localization length

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    One dimensional system of Dirac fermions with a random-varying mass is studied by the transfer-matrix methods which we developed recently. We investigate the effects of nonlocal correlation of the spatial-varying Dirac mass on the delocalization transition. Especially we numerically calculate both the "typical" and "mean" localization lengths as a function of energy and the correlation length of the random mass. To this end we introduce an imaginary vector potential as suggested by Hatano and Nelson and solve the eigenvalue problem. Numerical calculations are in good agreement with the results of the analytical calculations.Comment: 4 page
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