1,214 research outputs found

    Search for Lorentz Invariance and CPT Violation with the MINOS Far Detector

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    We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the standard-model extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20–510 over the current best limits found by using the MINOS near detector

    Improved Measurement of Muon Antineutrino Disappearance in MINOS

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    We report an improved measurement of ν̅_μ disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a ν̅_μ-enhanced configuration. From a total exposure of 2.95×10^20 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Δm̅^2=[2.62_(-0.28)^(+0.31)(stat)±0.09(syst)]×10^(-3)  eV^2 and constrain the ν_μ mixing angle sin^(2)(2θ̅)>0.75 (90% C.L.). These values are in agreement with Δm^2 and sin^(2)(2θ) measured for νμ, removing the tension reported in [ P. Adamson et al. Phys. Rev. Lett. 107 021801 (2011)]

    Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy x-ray diffraction

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    Structure factors for Cax/2AlxSi1-xO2 glasses (x=0,0.25,0.5,0.67) extended to a wave vector of magnitude Q= 40 1/A have been obtained by high-energy x-ray diffraction. For the first time, it is possible to resolve the contributions of Si-O, Al-O and Ca-O coordination polyhedra to the experimental atomic pair distribution functions (PDF). It has been found that both Si and Al are four-fold coordinated and so participate in a continuous tetrahedral network at low values of x. The number of network breaking defects in the form of non-bridging oxygens (NBO's) increases slowly with x until x=0.5 (NBO's ~ 10% at x=0.5). By x=0.67 the network breaking defects become significant as evidenced by the significant drop in the average coordination number of Si. By contrast, Al-O tetrahedra remain free of NBO's and fully integrated in the Al/Si-O network for all values of x. Calcium maintains a rather uniform coordination sphere of approximately 5 oxygen atoms for all values of x. The results suggest that not only Si/Al-O tetrahedra but Ca-O polyhedra, too, play a role in determining the glassy structure

    DISPERSION HARDENING OF A Mo--1 AT. PERCENT Hf ALLOY BY INTERNAL HARDENING.

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    Acoustical and Noise Control Criteria and Guidelines for Building Design and Operations

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    Noise, vibration and acoustical design, construction, commissioning and operation practices influence building cost, efficiency, performance and effectiveness. Parameters for structural vibration, building systems noise, acoustics and environmental noise crossing property boundaries will be presented with brief case studies illustrating noise and vibration problems with successful solutions. Building mechanical, power, and plumbing systems contribute to building operations noise and vibration, which affects building occupants, sensitive installations, and functional uses. Various noise and vibration design criteria, field measurements, design concepts and specifications can be applied in facilities to achieve noise mitigation and vibration control to enhance building operations and reduce tenant or neighbor problems. Concepts for enhancement will be presented that achieve specific program criteria and improve the built environment for occupants and functional uses, including items to incorporate in specifications and construction documents. Concepts relating to noise and vibration control can also reduce short and long-term operations costs and save energy. Acoustical designs can be implemented in new construction to achieve specific requirements for LEED certification in healthcare and educational facilities. Common problems, objective criteria, sensitive installations, and solutions will be presented to offer a basic understanding of effective noise and vibration control for central plant equipment, power systems, transformers, standby generators, and roof mounted HVAC equipment

    Paradigmatic status of an endo- and exoglucanase and its effect on crystalline cellulose degradation

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    BACKGROUND: Microorganisms employ a multiplicity of enzymes to efficiently degrade the composite structure of plant cell wall cellulosic polysaccharides. These remarkable enzyme systems include glycoside hydrolases (cellulases, hemicellulases), polysaccharide lyases, and the carbohydrate esterases. To accomplish this challenging task, several strategies are commonly observed either separately or in combination. These include free enzyme systems, multifunctional enzymes, and multi-enzyme self-assembled designer cellulosome complexes. RESULTS: In order to compare these different paradigms, we employed a synthetic biology approach to convert two different cellulases from the free enzymatic system of the well-studied bacterium, Thermobifida fusca, into bifunctional enzymes with different modular architectures. We then examined their performance compared to those of the combined parental free-enzyme and equivalent designer-cellulosome systems. The results showed that the cellulolytic activity displayed by the different architectures of the bifunctional enzymes was somewhat inferior to that of the wild-type free enzyme system. CONCLUSIONS: The activity exhibited by the designer cellulosome system was equal or superior to that of the free system, presumably reflecting the combined proximity of the enzymes and high flexibility of the designer cellulosome components, thus enabling efficient enzymatic activity of the catalytic modules

    PRECIPITATION HARDENING OF Mo--1 AT. PERCENT Hf BY INTERNAL NITRIDING.

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