20,820 research outputs found

    High spatial resolution observations of CUDSS14A: a SCUBA-selected ultraluminous galaxy at high redshift

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    The definitive version is available at www.blackwell-synergy.com '. Copyright Blackwell Publishing DOI : 10.1046/j.1365-8711.2000.03822.xWe present a high-resolutionmillimetre interferometric image of the brightest SCUBA- selected galaxy from the Canada-UK deep SCUBA survey (CUDSS). We make a very clear detection at 1.3 mm, but fail to resolve any structure in the source.Peer reviewe

    Response of selected microorganisms to experimental planetary environments

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    The anaerobic utilization of phosphite or phosphine and the significance of this conversion to potential contamination of Jupiter were investigated. A sporeforming organism was isolated from Cape Canaveral soil which anaerobically converts hypophosphite to phosphate. This conversion coincides with an increase in turbidity of the culture and with phosphate accumulation in the medium. Investigations of omnitherms (organisms which grow over a broad temperature range, i.e. 3 -55 C were also conducted. The cellular morphology of 28 of these isolates was investigated, and all were demonstrated to be sporeformers. Biochemical characterizations are also presented. Procedures for replicate plating were evaluated, and those results are also presented. The procedures for different replicate-plating techniques are presented, and these are evaluated on the basis of reproducibility, percentage of viable transfer, and ease of use. Standardized procedures for the enumeration of microbial populations from ocean-dredge samples from Cape Canaveral are also presented

    Array Processing of Rayleigh Waves for Shear Structure

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    Site response to earthquakes is strongly dependent on shallow shear wave velocity structure β(z), and evidence suggests that soil strength and liquefaction potential depends on it as well. We have determined β(z) at several sites by inversion of dispersion data from Rayleigh waves recorded on linear arrays of geophones using artificial sources. Improved methods have been developed for extracting phase and group velocities that lead to significantly more stable and accurate inversion results

    Non-abelian dynamics in first-order cosmological phase transitions

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    Bubble collisions in cosmological phase transitions are explored, taking the non-abelian character of the gauge fields into account. Both the QCD and electroweak phase transitions are considered. Numerical solutions of the field equations in several limits are presented.Comment: 8 pages, 2 figures. Contribution to the CosPA 2003 Cosmology and Particle Astrophysics Symposium. Typos correcte

    Efficacy of B-cell-targeted therapy with rituximab in patients with rheumatoid arthritis.

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    BACKGROUND: An open-label study indicated that selective depletion of B cells with the use of rituximab led to sustained clinical improvements for patients with rheumatoid arthritis. To confirm these observations, we conducted a randomized, double-blind, controlled study. METHODS: We randomly assigned 161 patients who had active rheumatoid arthritis despite treatment with methotrexate to receive one of four treatments: oral methotrexate (> or =10 mg per week) (control); rituximab (1000 mg on days 1 and 15); rituximab plus cyclophosphamide (750 mg on days 3 and 17); or rituximab plus methotrexate. Responses defined according to the criteria of the American College of Rheumatology (ACR) and the European League against Rheumatism (EULAR) were assessed at week 24 (primary analyses) and week 48 (exploratory analyses). RESULTS: At week 24, the proportion of patients with 50 percent improvement in disease symptoms according to the ACR criteria, the primary end point, was significantly greater with the rituximab-methotrexate combination (43 percent, P=0.005) and the rituximab-cyclophosphamide combination (41 percent, P=0.005) than with methotrexate alone (13 percent). In all groups treated with rituximab, a significantly higher proportion of patients had a 20 percent improvement in disease symptoms according to the ACR criteria (65 to 76 percent vs. 38 percent, P< or =0.025) or had EULAR responses (83 to 85 percent vs. 50 percent, P< or =0.004). All ACR responses were maintained at week 48 in the rituximab-methotrexate group. The majority of adverse events occurred with the first rituximab infusion: at 24 weeks, serious infections occurred in one patient (2.5 percent) in the control group and in four patients (3.3 percent) in the rituximab groups. Peripheral-blood immunoglobulin concentrations remained within normal ranges. CONCLUSIONS: In patients with active rheumatoid arthritis despite methotrexate treatment, a single course of two infusions of rituximab, alone or in combination with either cyclophosphamide or continued methotrexate, provided significant improvement in disease symptoms at both weeks 24 and 48

    A Routh-like algorithm in system identification and adaptive control

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    This paper introduces algorithms to be used for finding the Cauchy index of a transfer function and for solving the Diophantine equation. The algorithms are similar to the Routh-Hurwitz array in structure and are simple to implement. The first algorithm also provides a simple check for the presence of almost common factors between two polynomials, and so is useful as a computationally inexpensive alternative to the sylvester determinant. It also finds the almost common factor, and so is potentially useful as an alternative to [8] in implementing self-tuning regulators for nonminimum-phase systems [6]

    Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

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    A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C60_{60} molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH2_2, or methyl group CH3_3, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range 0.1á0.30.1\div 0.3 eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

    Offensive Cyber Working Group: Scoping Workshop Report

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    Radiative convective equilibrium as a framework for studying the interaction between convection and its large-scale environment

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    An uncertain representation of convective clouds has emerged as one ofthe key barriers to our understanding of climate sensitivity. The largegap in resolved spatial scales between General Circulation Models (GCMs)and high resolution models has made a systematic study of convectiveclouds across model configurations difficult. It is shown here that thesimulated atmosphere of a GCM in Radiative Convective Equilibrium (RCE)is sufficiently similar across a range of domain sizes to justify theuse of RCE to study both a GCM and a high resolution model on the samedomain with the goal of improved constraints on the parameterizedclouds. Simulations of RCE with parameterized convection have beenanalyzed on domains with areas spanning more than two orders ofmagnitude (0.80-204x10(6)km(2)), all having the same grid spacing of13km. The simulated climates on different domains are qualitativelysimilar in their degree of convective organization, the precipitationrates, and the vertical structure of the clouds and water vapor, withthe similarity increasing as the domain size increases. Sea surfacetemperature perturbation experiments are used to estimate the climatefeedback parameter for the differently configured experiments, and thecloud radiative effect is computed to examine the role which clouds playin the response. Despite the similar climate states between the domainsthe feedback parameter varies by more than a factor of two; thehydrological sensitivity parameter is better behaved, varying by afactor of 1.4. The sensitivity of the climate feedback parameter todomain size is related foremost to a nonsystematic response of low-levelclouds as well as an increasingly negative longwave feedback on largerdomains

    Worker heterogeneity, new monopsony, and training

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    A worker's output depends not only on his/her own ability but also on that of colleagues, who can facilitate the performance of tasks that each individual cannot accomplish on his/her own. We show that this common-sense observation generates monopsony power and is sufficient to explain why employers might expend resources on training employees even when the training is of use to other firms. We show that training will take place in better-than-average or ‘good’ firms enjoying greater monopsony power, whereas ‘bad’ firms will have low-ability workers unlikely to receive much training
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