436 research outputs found

    The response of the Western Equatorial Pacific ocean to Westerly wind bursts during november 1989 to january 1990

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    Several 5 to 10 m s-1 westerly wind bursts of 10-15 days' duration occurred in the Western Equatorial Pacific during november 1989 to January 1990. The response to these wind bursts was characterized by a 400- to 600 km wide eastward jet in the upper 100-150 m along the equator between 135°E and the date line. Flow in this jet accelarated to speeds of over 100 cm s-1 within 1 week after the onset of westerly winds in november 1989 in association with super thyphoon Irma. In addition, a 20 to 40 cm s-1 westward counterflow developed between 2°N and 2°S below the surface jet separating it from the eastward flow of the Equatorial undercurrent in the thermocline. Changes in surface layer zonal volume transport in the Western Pacific due to westerly wind bursts were 25-56 Sv based on comparison of three shipboard velocity transects in november and december 1989. Although fluctuations in current speeds in the thermocline were generally smaller and less directly related to local wind forcing than those in the surface layer, the Equatorial undercurrent decelerated to less than 20 cm s-1 (i.e., less than half its speed before the onset of westerlies) by early december 1989. (D'aprÚs résumé d'auteur

    Chloride movement in a de-watered saline soil profile

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    Surface ripping affected the downward movement of water and solutes within a saline dewatered duplex soil profile near Kellerberrin. Prior to ripping, 63% of the total rainfall ended up as runoff and there was little evidence from tensiometric measurements and soil solution samples of significant downward flows of water below a depth of 0.3m. Following ripping to a depth of 0.2m to break a near surface hard layer: runoff was reduced to around 13%; there was some change in soil matrix potential; some leaching of the surface soil occurred; and several preferred water fluxes were intercepted at a depth of 1.5m. These intercepted fluxes were recorded shortly after (<1hr) high intensity rainfall greater than 20mm, suggesting post ripping flow through macropores. The initial chloride storage in the profile was 162t ha-1, approximately 5t ha-1 chloride was leached during the field study (3%). The main leaching mechanism before ripping was runoff (0.5t ha-1). After ripping, flow through macropores and mesopores accounted for 0.5t ha-1 , runoff 0.09t ha-1 with the rest redistributed through the soil matrix

    Nonresonant Three-body Decays of D and B Mesons

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    Nonresonant three-body decays of D and B mesons are studied. It is pointed out that if heavy meson chiral perturbation theory (HMChPT) is applied to the heavy-light strong and weak vertices and assumed to be valid over the whole kinematic region, then the predicted decay rates for nonresonant charmless 3-body B decays will be too large and especially B^- --> pi^- K^+ K^- greatly exceeds the current experimental limit. This can be understood as chiral symmetry has been applied there twice beyond its region of validity. If HMChPT is applied only to the strong vertex and the weak transition is accounted for by the form factors, the dominant B^* pole contribution to the tree-dominated direct three-body B decays will become small and the branching ratio will be of order 10^{-6}. The decay modes B^- --> (K^- h^+ h^-)_{NR} and bar{B}^0 --> (bar{K}^0 h^+h^-)_{NR} for h = pi, K are penguin dominated. We apply HMChPT in two different cases to study the direct 3-body D decays and compare the results with experiment. Theoretical uncertainties are discussed.Comment: 24 pages, 2 figures. New experimental results of direct 3-body D decays as Reported at ICHEP2002 are included. To appear in Phys. Re

    Quantum central limit theorem for continuous-time quantum walks on odd graphs in quantum probability theory

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    The method of the quantum probability theory only requires simple structural data of graph and allows us to avoid a heavy combinational argument often necessary to obtain full description of spectrum of the adjacency matrix. In the present paper, by using the idea of calculation of the probability amplitudes for continuous-time quantum walk in terms of the quantum probability theory, we investigate quantum central limit theorem for continuous-time quantum walks on odd graphs.Comment: 19 page, 1 figure

    Quantum walk on distinguishable non-interacting many-particles and indistinguishable two-particle

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    We present an investigation of many-particle quantum walks in systems of non-interacting distinguishable particles. Along with a redistribution of the many-particle density profile we show that the collective evolution of the many-particle system resembles the single-particle quantum walk evolution when the number of steps is greater than the number of particles in the system. For non-uniform initial states we show that the quantum walks can be effectively used to separate the basis states of the particle in position space and grouping like state together. We also discuss a two-particle quantum walk on a two- dimensional lattice and demonstrate an evolution leading to the localization of both particles at the center of the lattice. Finally we discuss the outcome of a quantum walk of two indistinguishable particles interacting at some point during the evolution.Comment: 8 pages, 7 figures, To appear in special issue: "quantum walks" to be published in Quantum Information Processin

    Exploring morphological correlations among H2CO, 12CO, MSX and continuum mappings

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    There are relatively few H2CO mappings of large-area giant molecular cloud (GMCs). H2CO absorption lines are good tracers for low-temperature molecular clouds towards star formation regions. Thus, the aim of the study was to identify H2CO distributions in ambient molecular clouds. We investigated morphologic relations among 6-cm continuum brightness temperature (CBT) data and H2CO (111-110; Nanshan 25-m radio telescope), 12CO (1--0; 1.2-m CfA telescope) and midcourse space experiment (MSX) data, and considered the impact of background components on foreground clouds. We report simultaneous 6-cm H2CO absorption lines and H110\alpha radio recombination line observations and give several large-area mappings at 4.8 GHz toward W49 (50'\times50'), W3 (70'\times90'), DR21/W75 (60'\times90') and NGC2024/NGC2023 (50'\times100') GMCs. By superimposing H2CO and 12CO contours onto the MSX color map, we can compare correlations. The resolution for H2CO, 12CO and MSX data was about 10', 8' and 18.3", respectively. Comparison of H2CO and 12CO contours, 8.28-\mu m MSX colorscale and CBT data revealed great morphological correlation in the large area, although there are some discrepancies between 12CO and H2CO peaks in small areas. The NGC2024/NGC2023 GMC is a large area of HII regions with a high CBT, but a H2CO cloud to the north is possible against the cosmic microwave background. A statistical diagram shows that 85.21% of H2CO absorption lines are distributed in the intensity range from -1.0 to 0 Jy and the \Delta V range from 1.206 to 5 km/s.Comment: 18 pages, 22 figures, 5 tables. Accepted to be published in Astrophysics and Space Scienc

    Lepton polarization correlations in B→K∗τ−τ+B \to K^* \tau^- \tau^+

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    In this work we will study the polarizations of both leptons (τ\tau) in the decay channel B→K∗τ−τ+B\to K^* \tau^- \tau^+. In the case of the dileptonic inclusive decay B→K∗ℓ−ℓ+B\to K^* \ell^- \ell^+, where apart from the polarization asymmetries of single lepton ℓ\ell, one can also observe the polarization asymmetries of both leptons simultaneously. If this sort of measurement is possible then we can have, apart from decay rate, FB asymmetry and the six single lepton polarization asymmetries (three each for ℓ−\ell^- and ℓ+\ell^+), nine more double polarization asymmetries. This will give us a very useful tool in more strict testing of SM and the physics beyond. We discuss the double polarization asymmetries of τ\tau leptons in the decay mode B→K∗τ−τ+B\to K^* \tau^- \tau^+ within the SM and the Minimal Supersymmetric extensions of it.Comment: 21 pages, 21 figures; version to match paper to appear in PR

    DNA methylation is required to maintain both DNA replication timing precision and 3D genome organization integrity

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    DNA replication timing and three-dimensional (3D) genome organization are associated with distinct epigenome patterns across large domains. However, whether alterations in the epigenome, in particular cancer-related DNA hypomethylation, affects higher-order levels of genome architecture is still unclear. Here, using Repli-Seq, single-cell Repli-Seq, and Hi-C, we show that genome-wide methylation loss is associated with both concordant loss of replication timing precision and deregulation of 3D genome organization. Notably, we find distinct disruption in 3D genome compartmentalization, striking gains in cell-to-cell replication timing heterogeneity and loss of allelic replication timing in cancer hypomethylation models, potentially through the gene deregulation of DNA replication and genome organization pathways. Finally, we identify ectopic H3K4me3-H3K9me3 domains from across large hypomethylated domains, where late replication is maintained, which we purport serves to protect against catastrophic genome reorganization and aberrant gene transcription. Our results highlight a potential role for the methylome in the maintenance of 3D genome regulation
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