32 research outputs found

    Government-Industry Cooperative Fisheries Research in the North Pacific under the MSFCMA

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    The National Marine Fisheries Service’s Alaska Fisheries Science Center (AFSC) has a long and successful history of conducting research in cooperation with the fishing industry. Many of the AFSC’s annual resource assessment surveys are carried out aboard chartered commercial vessels and the skill and experience of captains and crew are integral to the success of this work. Fishing companies have been contracted to provide vessels and expertise for many different types of research, including testing and evaluation of survey and commercial fishing gear and development of improved methods for estimating commercial catch quantity and composition. AFSC scientists have also participated in a number of industry-initiated research projects including development of selective fishing gears for bycatch reduction and evaluating and improving observer catch composition sampling. In this paper, we describe the legal and regulatory provisions for these types of cooperative work and present examples to illustrate the process and identify the requirements for successful cooperative research

    Rapid Tunneling and Percolation in the Landscape

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    Motivated by the possibility of a string landscape, we reexamine tunneling of a scalar field across single/multiple barriers. Recent investigations have suggested modifications to the usual picture of false vacuum decay that lead to efficient and rapid tunneling in the landscape when certain conditions are met. This can be due to stringy effects (e.g. tunneling via the DBI action), or by effects arising due to the presence of multiple vacua (e.g. resonance tunneling). In this paper we discuss both DBI tunneling and resonance tunneling. We provide a QFT treatment of resonance tunneling using the Schr\"odinger functional approach. We also show how DBI tunneling for supercritical barriers can naturally lead to conditions suitable for resonance tunneling. We argue using basic ideas from percolation theory that tunneling can be rapid in a landscape where a typical vacuum has multiple decay channels and discuss various cosmological implications. This rapidity vacuum decay can happen even if there are no resonance/DBI tunneling enhancements, solely due to the presence of a large number of decay channels. Finally, we consider various ways of circumventing a recent no-go theorem for resonance tunneling in quantum field theory.Comment: 47 pages, 16 figures. Acknowledgements adde

    Search for Interstellar Water in the Translucent Molecular Cloud toward HD 154368

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    We report an upper limit of 9 x 10^{12} cm-2 on the column density of water in the translucent cloud along the line of sight toward HD 154368. This result is based upon a search for the C-X band of water near 1240 \AA carried out using the Goddard High Resolution Spectrograph of the Hubble Space Telescope. Our observational limit on the water abundance together with detailed chemical models of translucent clouds and previous measurements of OH along the line of sight constrain the branching ratio in the dissociative recombination of H_3O+ to form water. We find at the 3σ3\sigma level that no more than 30% of dissociative recombinations of H_3O+ can lead to H_2O. The observed spectrum also yielded high-resolution observations of the Mg II doublet at 1239.9 \AA and 1240.4 \AA, allowing the velocity structure of the dominant ionization state of magnesium to be studied along the line of sight. The Mg II spectrum is consistent with GHRS observations at lower spectral resolution that were obtained previously but allow an additional velocity component to be identified.Comment: Accepted by ApJ, uses aasp

    Understanding earthquake hazards in southern California - the "LARSE" project - working toward a safer future for Los Angeles

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    The Los Angeles region is underlain by a network of active faults, including many that are deep and do not break the Earth’s surface. These hidden faults include the previously unknown one responsible for the devastating January 1994 Northridge earthquake, the costliest quake in U.S. history. So that structures can be built or strengthened to withstand the quakes that are certain in the future, the Los Angeles Region Seismic Experiment (LARSE) is locating hidden earthquake hazards beneath the region to help scientists determine where the strongest shaking will occur

    Calibration of Northern Anchovy Spawning Biomass Estimates Derived by Egg Production and Larval Census Methods

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    ABSTRACT A mathematical procedure is developed for converting estimates of northern anchovy spawning biomass derived by egg production methods to values equivalent to those derived by larval census methods. This calibration is based on the results of concurrent spawning biomass surveys conducted for both methods in 1980 and 1981. Two egg production surveys were made in 1981. The coefficient of proportionality for the two biomass estimators is not a simple constant but a function of egg survival, daily population fecundity, and larval mortality rate-all of which may vary from year to year. The common link between these two biomass estimators is the daily production of larvae at the time of hatching. The coefficient of proportionality between the hatching rates derived from the two estimators is relatively constant for the three test cases. The proposed equation for converting egg production estimates of spawning biomass to equivalent larval census estimates may result in a bias of 3.1% in the equivalent larval census estimate. RESUMEN Se desarrolla un procedimiento matemitico para convertir estimaciones de la biomasa de la puesta de Engraulis mordax (anchoa), derivado de 10s mktodos equivalentes para la produccion de huevos y del censo larval. Esta calibracion esti basada en 10s resultados obtenidos sobre la biomasa de la puesta utilizando ambos mCtodos, durante exploraciones en 1980 y 1981. En 1981 se efectuaron dos exploraciones para determinar la produccion de huevos. El coeficiente de proporcionalidad para 10s dos valores en la estimacion de la biomasa, no es una constante simple, sino una funcion de la supervivencia de huevos, fecundidad diaria de la poblacion y valor de la mortalidad larval, factores que varian de un afio para otro. El eslabon comun entre estas dos estimaciones de la biomasa es la eclosi6n diaria de larvas. El coeficiente de proporcionalidad entre 10s valores de eclosion derivados de 10s dos valores estimados result6 relativamente constante para las tres pruebas efectuadas. La ecuacion que se propone para convertir la estimacion de la produccion de huevos en la estimacion de la biomasa de la puesta y la estimacidn equivalente del censo de larvas, puede resultar con una desviacion del 3.1% en la estimacion equivalente del censo de larvas

    Human aging and CD31+ T-cell number, migration, apoptotic susceptibility, and telomere length

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    CD31+ T cells, or so-called “angiogenic T cells,” have been shown to demonstrate vasculoprotective and neovasculogenic qualities. The influence of age on CD31+ T-cell number and function is unclear. We tested the hypothesis that circulating CD31+ T-cell number and migratory capacity are reduced, apoptotic susceptibility is heightened, and telomere length is shortened with advancing age in adult humans. Thirty-six healthy, sedentary men were studied: 12 young (25 ± 1 yr), 12 middle aged (46 ± 1 yr), and 12 older (64 ± 2 yr). CD31+ T cells were isolated from peripheral blood samples by magnetic-activated cell sorting. The number of circulating CD31+ T cells (fluorescence-activated cell sorting analysis) was lower (P < 0.01) in older (24% of CD3+ cells) compared with middle-aged (38% of CD3+ cells) and young (40% of CD3+ cells) men. Migration (Boyden chamber) to both VEGF and stromal cell-derived factor-1α was markedly blunted (P < 0.05) in cells harvested from middle-aged [306.1 ± 45 and 305.6 ± 46 arbitrary units (AU), respectively] and older (231 ± 65 and 235 ± 62 AU, respectively) compared with young (525 ± 60 and 570 ± 62 AU, respectively) men. CD31+ T cells from middle-aged and older men demonstrated greater apoptotic susceptibility, as staurosporine-stimulated intracellular caspase-3 activation was ∼40% higher (P < 0.05) than young. There was a progressive age-related decline in CD31+ T-cell telomere length (young: 10,706 ± 220 bp; middle-aged: 10,179 ± 251 bp; and older: 9,324 ± 192 bp). Numerical and functional impairments in this unique T-cell subpopulation may contribute to diminished angiogenic potential and greater cardiovascular risk with advancing age
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