4,950 research outputs found

    Multi-use lunar telescopes

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    The objective of multi-use telescopes is to reduce the initial and operational costs of space telescopes to the point where a fair number of telescopes, a dozen or so, would be affordable. The basic approach is to develop a common telescope, control system, and power and communications subsystem that can be used with a wide variety of instrument payloads, i.e., imaging CCD cameras, photometers, spectrographs, etc. By having such a multi-use and multi-user telescope, a common practice for earth-based telescopes, development cost can be shared across many telescopes, and the telescopes can be produced in economical batches

    CP-PACS Result for the Quenched Light Hadron Spectrum

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    The quenched hadron spectrum in the continuum obtained with the Wilson quark action in recent simulations on the CP-PACS is presented. Results for the light quark masses and the QCD scale parameter are reported.Comment: Talk presented by K. Kanaya at Lattice97, Edinburg

    CP-PACS results for quenched QCD spectrum with the Wilson action

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    We present progress report of a CP-PACS calculation of quenched QCD spectrum with the Wilson quark action. Light hadron masses and meson decay constants are obtained at ÎČ=\beta=5.9, 6.1, and 6.25 on lattices with a physical extent of 3 fm, and for the range of quark mass corresponding to mπ/mρ≈0.75m_\pi/m_\rho \approx 0.75 −- 0.4. Nucleon mass at each ÎČ\beta appears to be a convex function of quark mass, and consequently the value at the physical quark mass is much smaller than previously thought. Hadron masses extrapolated to the continuum limit exhibits a significant deviation from experimental values: with KK meson mass to fix strange quark mass, strange meson and baryon masses are systematically lower. Light quark masses determined from the axial Ward identity are shown to agree with those from perturbation theory in the continuum limit. Decay constants of mesons are also discussed.Comment: 12 pages, Latex(espcrc2,epsf), 17 ps figures. Talk presented by T.Yoshi\'e at the International Workshop on ``LATTICE QCD ON PARALLEL COMPUTERS'', 10-15 March 1997, Center for Computational Physics, University of Tsukub

    Radiative D∗D^* Decay Using Heavy Quark and Chiral Symmetry

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    The implications of chiral SU(3)L×SU(3)RSU(3)_L \times SU(3)_R symmetry and heavy quark symmetry for the radiative decays D∗0→D0ÎłD^{*0}\to D^0\gamma, D∗+→D+ÎłD^{*+}\to D^+\gamma, and Ds∗→DsÎłD_s^*\to D_s\gamma are discussed. Particular attention is paid to SU(3)SU(3) violating contributions of order mq1/2m_q^{1/2}. Experimental data on these radiative decays provide constraints on the D∗DπD^* D\pi coupling.Comment: 9 pages plus 3 pages of figures in POSTSCRIPT file appended to TeX file (uses harvmac.tex and tables.tex), UCSD/PTH 92-31, CALT-68-1816, EFI-92-45, CERN-TH.6650/9

    Quenched Light Hadron Spectrum with the Wilson Quark Action: Final Results from CP-PACS

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    We report the final results of the CP-PACS calculation for the quenched light hadron spectrum with the Wilson quark action. Our data support the presence of quenched chiral singularities, and this motivates us to use mass formulae based on quenched chiral perturbation theory in order to extrapolate hadron masses to the physical point. Hadron masses and decay constants in the continuum limit show unambiguous systematic deviations from experiment. We also report the results for light quark masses.Comment: LATTICE98(spectrum). The poster at Lattice98 can be obtained from http://www.rccp.tsukuba.ac.jp/people/yoshie/Lat98.Poster

    Surface ocean-lower atmosphere study: Scientific synthesis and contribution to Earth system science

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    The domain of the surface ocean and lower atmosphere is a complex, highly dynamic component of the Earth system. Better understanding of the physics and biogeochemistry of the air-sea interface and the processes that control the exchange of mass and energy across that boundary define the scope of the Surface Ocean-Lower Atmosphere Study (SOLAS) project. The scientific questions driving SOLAS research, as laid out in the SOLAS Science Plan and Implementation Strategy for the period 2004-2014, are highly challenging, inherently multidisciplinary and broad. During that decade, SOLAS has significantly advanced our knowledge. Discoveries related to the physics of exchange, global trace gas budgets and atmospheric chemistry, the CLAW hypothesis (named after its authors, Charlson, Lovelock, Andreae and Warren), and the influence of nutrients and ocean productivity on important biogeochemical cycles, have substantially changed our views of how the Earth system works and revealed knowledge gaps in our understanding. As such SOLAS has been instrumental in contributing to the International Geosphere Biosphere Programme (IGBP) mission of identification and assessment of risks posed to society and ecosystems by major changes in the Earth́s biological, chemical and physical cycles and processes during the Anthropocene epoch. SOLAS is a bottom-up organization, whose scientific priorities evolve in response to scientific developments and community needs, which has led to the launch of a new 10-year phase. SOLAS (2015–2025) will focus on five core science themes that will provide a scientific basis for understanding and projecting future environmental change and for developing tools to inform societal decision-making

    CD2AP links cortactin and capping protein at the cell periphery to facilitate formation of lamellipodia

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    Understanding the physiology of complex relationships between components of signaling pathways and the actin cytoskeleton is an important challenge. CD2AP is a membrane scaffold protein implicated in a variety of physiological and disease processes. The physiological function of CD2AP is unclear, but its biochemical interactions suggest that it has a role in dynamic actin assembly. Here, we report that CD2AP functions to facilitate the recruitment of actin capping protein (CP) to the Src kinase substrate, cortactin, at the cell periphery, and that this is necessary for formation of the short branched filaments that characterize lamellipodium formation and are required for cell migration. Superresolution fluorescence microscopy demonstrated that the efficient colocalization of CP and cortactin at the cell periphery required CD2AP. As both cortactin and CP function to enhance branched actin filament formation, CD2AP functions synergistically to enhance the function of both proteins. Our data demonstrate how the interplay between specialized actin regulatory molecules shapes the actin cytoskeleton

    From Notes to Chords in QCD

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    After a very brief overview recollecting the `classic' parts of QCD, that is its application to describe hard processes and static properties of hadrons, I survey recent work -- some very recent -- on QCD at non-zero temperature and density. At finite temperature and zero density there is a compelling theoretical framework allowing us to predict highly specific, non-trivial dependence of the phase structure on the number of flavors and colors. Several aspects have been rigorously, and successfully, tested against massive numerical realizations of the microscopic theory. The theoretical description of high density is nowhere near as mature, but some intriguing possibilities have been put forward. The color/flavor locked state recently proposed for three flavors has many remarkable features connected to its basic symmetry structure, notably including chiral symmetry re-breaking and the existence (unlike for two flavors) of a gauge invariant order parameter. I survey potential applications to heavy ion collisions, astrophysics, and cosmology. A noteworthy possibility is that stellar explosions are powered by release of QCD latent heat.Comment: LaTeX, 13 pages, 1 figure. Reference added. Will appear in Proceedings of QCD at Finite Baryon Density Conference, April 1998, Universitaet Bielefeld, German

    Full QCD simulation on CP-PACS

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    A status report is made of an on-going full QCD study on the CP-PACS aiming at a comparative analysis of the effects of improving gauge and quark actions on hadronic quantities and static quark potential. Simulations are made for four action combinations, the plaquette or an RG-improved action for gluons and the Wilson or SW-clover action for quarks, at a−1≈1.1a^{-1} \approx 1.1-1.3GeV and mπ/mρ≈0.7m_\pi/m_\rho \approx 0.7-0.9. Results demonstrate clearly that the clover term markedly reduces discretization errors for hadron spectrum, while adding six-link terms to the plaquette action leads to much better rotational symmetry in the potential. These results extend experience with quenched simulations to full QCD.Comment: Talk presented by K. Kanaya at the International Workshop on ``LATTICE QCD ON PARALLEL COMPUTERS'', 10-15 March 1997, Center for Computational Physics, University of Tsukub
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