1,725 research outputs found

    A Brief History of Bycatch Management Measures for Eastern Bering Sea Groundfish Fisheries

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    Bycatch management measures instituted for groundfish fisheries of the eastern Bering Sea have focused on reducing the incidental capture and injury of species traditionally harvested by other fisheries. These species include king crab, Paralithodes and Lithodes spp.; Tanner crab, Chionoecetes spp.; Pacific herring, Clupea harengus pallasi; Pacific halibut, Hippoglossus stenolepis; and Pacific salmon and steelhead trout, Oncorhynchus spp. Collectively, these species are called "prohibited species," as they cannot be retained as bycatch in groundfish fisheries and must be discarded with a minimum of injury

    Beauty Quark Fragmentation Into Strange B Mesons

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    Using the recent measurement of the total production rate for BsB_s and BsB_s^* mesons in electron-positron annihilation to determine the strange quark mass parameter in the bˉBs,Bs\bar b\to B_s,\, B_s^* fragmentation functions we calculate the momentum distributions of the BsB_s and BsB_s^* mesons.Comment: 8 pages, 2 figures (not included but available upon request), standard LaTeX file, Report # NUHEP-TH-94-1

    Ecosystem-based Management for Protected Species in the North Pacific Fisheries

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    In the North Pacific Ocean, an ecosystem-based fishery management approach has been adopted. A significant objective of this approach is to reduce interactions between fishery-related activities and protected species. We review management measures developed by the North Pacific Fishery Management Council and the National Marine Fisheries Service to reduce effects of the groundfish fisheries off Alaska on marine mammals and seabirds, while continuing to provide economic opportunities for fishery participants. Direct measures have been taken to mitigate known fishery impacts, and precautionary measures have been taken for species with potential (but no documented) interactions with the groundfish fisheries. Area closures limit disturbance to marine mammals at rookeries and haulouts, protect sensitive benthic habitat, and reduce potential competition for prey resources. Temporal and spatial dispersion of catches reduce the localized impact of fishery removals. Seabird avoidance measures have been implemented through collaboration with fishery participants and have been highly successful in reducing seabird bycatch. Finally, a comprehensive observer monitoring program provides data on the location and extent of bycatch of marine mammals and seabirds. These measures provide managers with the flexibility to adapt to changes in the status of protected species and evolving conditions in the fisheries. This review should be useful to fishery managers as an example of an ecosystem-based approach to protected species management that is adaptive and accounts for multiple objectives

    Calculating the Shear and Divergence of Light Rays

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    The purpose of this research was to calculate the shear and divergence of light rays bundles as they pass black holes. We defined a Lagrangian using the Schwarzchild metric then used the Euler-Lagrangian equation to create 6 first order OED’s for the light rays path. Next we found tangent vectors to the light ray so we could calculate Ψ0. In order to calculate the shear and divergence the method of calculation required simultaneously solving 16 ordinary differential equations. We used Mathematica to calculate how these light rays act but first we had to use calculus and algebra to derive these equations. We started from the Schwarzchild metric to find the Langrangian for the motion of the light rays. We then got results which were 6 ODE’s that gave velocity and acceleration in (Τ, r, θ, ϕ). Then we found the tangent vectors to these paths which allows us to solve for Ψ0 and finally we solved for the divergence and shear of the light rays

    On the Determination of a1a_1 and a2a_2 from Hadronic Two Body BB Decays

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    {}From Class I decays : B^o \ra \pi^+ ( \rho^+ ) + D^- ( {D^*}^- ), we determine a1a_1, and from Class III decays : B^+ \ra \pi^+ ( \rho^+ ) + \ol{D}^o ( {\ol{D}^*}^o ), we determine an allowed domain in the (a1,a2)( a_1, a_2 ) plane. We find that within one standard deviation errors, the allowed band of a1a_1 from Class I decays is at least three standard deviations removed from the allowed domain (a1,a2)( a_1, a_2 ) from Class III decays.If we expand the experimental errors to two standard deviations we do find a small intersection between the a1a_1 band and the allowed (a1,a2)( a_1, a_2 ) domain. The results usually quoted in the literature lie in this intersection. We suggest : (1) an independent measurement of the branching ratio for the Class III decay, B^+ \ra \rho^+ \ol{D}^o , (2) a high-statistics measurement of the branching ratio of the Class I decay, B \ra \ol{D} ( \ol{D}^* ) + D_s ( D_s^* ) in both charged states, and (3) a measurement of the longitudinal polarization fraction in the Class III decay B^+ \ra \rho^+ {\ol{D}^*}^o to shed more light on the questions involved .Comment: 9pages(Latex)+4 figures(PS file appended), PAR/LPTHE/94-2

    Implications of factorization for the determination of hadronic form factors in D_s^+ \ra \phi transition

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    Using factorization we determine the allowed domains of the ratios of form factors, x=A2(0)/A1(0)x = A_2(0)/A_1(0) and y=V(0)/A1(0)y = V(0)/A_1(0), from the experimentally measured ratio R_h \equiv \Gamma(D_s^+ \ra \phi \rho^+)/\Gamma(D_s^+ \ra \phi \pi^+) assuming three different scenarios for the q2q^2-dependence of the form factors. We find that the allowed domains overlap with those obtained by using the experimentally measured ratio R_{s\ell} = \Gamma(D^+_s \ra \phi \ell^+ \nu_{\ell})/\Gamma(D^+_s \ra \phi \pi^+) provided that the phenomenological parameter a1a_1 is 1.231.23. Such a comparison presents a genuine test of factorization. We calculate the longitudinal polarization fraction, \Gamma_L/\Gamma \equiv \Gamma(D_s^+ \ra \phi_L \rho^+_L)/\Gamma(D_s^+ \ra \phi \rho^+), in the three scenarios for the q2q^2-dependence of the form factors and emphasize the importance of measuring ΓL/Γ\Gamma_L/\Gamma . Finally we discuss the q2q^2-distribution of the semileptonic decay and find that it is rather insensitive to the scenarios for the q2q^2-dependence of the form factors, and unless very accurate data can be obtained it is unlikely to discriminate between the different scenarios. Useful information on the value of xx might be obtained by the magnitude of the q2q^2-distribution near q2=0q^2 = 0. However the most precise information on xx and yy would come from the knowledge of the longitudinal and left-right transverse polarizations of the final vector mesons in hadronic and/or semileptonic decays.Comment: Latex 10 pages( 4 figures), PAR/LPTHE/94-3

    AIERO: An algorithm for identifying engineering relationships in ontologies

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    Semantic technologies are playing an increasingly popular role as a means for advancing the capabilities of knowledge management systems. Among these advancements, researchers have successfully leveraged semantic technologies, and their accompanying techniques, to improve the representation and search capabilities of knowledge management systems. This paper introduces a further application of semantic techniques. We explore semantic relatedness as a means of facilitating the development of more “intelligent” engineering knowledge management systems. Using semantic relatedness quantifications to analyze and rank concept pairs, this novel approach exploits semantic relationships to help identify key engineering relationships, similar to those leveraged in change management systems, in product development processes. As part of this work, we review several different semantic relatedness techniques, including a meronomic technique recently introduced by the authors. We introduce an aggregate measure, termed “An Algorithm for Identifying Engineering Relationships in Ontologies,” or AIERO, as a means to purposely quantify semantic relationships within product development frameworks. To assess its consistency and accuracy, AIERO is tested using three separate, independently developed ontologies. The results indicate AIERO is capable of returning consistent rankings of concept pairs across varying knowledge frameworks. A PCB (printed circuit board) case study then highlights AIERO’s unique ability to leverage semantic relationships to systematically narrow where engineering interdependencies are likely to be found between various elements of product development processes

    Form Factor Relations for Heavy-to-Light Transitions

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    Assuming simple properties of the spectator particle in weak decays the form factors of hadronic current matrix elements are shown to be related to a single universal function. The Isgur-Wise result for heavy-to-heavy transitions follows as well as similar relations for heavy-to-light decay processes. The approximation should hold for total energies of the final particle large compared to the confinement scale. A comparison with experimentally determined D-decay form factors and QCD sum rule results for B-decays is very encouraging.Comment: 12 pages, Latex; Relativistic covariant form, results unchanged, references added, to be published in Physics Lett.
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