8,462 research outputs found

    Mariculture in California

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    Mariculture in California is currently under development by several private concerns, universities, and by the California Department of Fish and Game. At present, most of these efforts classify as research and development with a few in the pilot production phase. The Department of Fish and Game is presently conducting research in the culture of mortality resistant strains of Pacific oyster, Crassostrea virginica, the red abalone, Haliotis rufescens, and the spot prawn, Pandalus platyceros. (18pp.

    Spin projection and spin current density within relativistic electronic transport calculations

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    A spin projection scheme is presented which allows the decomposition of the electric conductivity into two different spin channels within fully relativistic abab initioinitio transport calculations that account for the impact of spin-orbit coupling. This is demonstrated by calculations of the spin-resolved conductivity of Fe1−x_{1-x}Crx_x and Co1−x_{1-x}Ptx_x disordered alloys on the basis of the corresponding Kubo-Greenwood equation implemented using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) band structure method. In addition, results for the residual resistivity of diluted Ni-based alloys are presented that are compared to theoretical and experimental ones that rely on Mott's two-current model for spin-polarized systems. The application of the scheme to deal with the spin-orbit induced spin Hall effect is discussed in addition

    Masses of light tetraquarks and scalar mesons in the relativistic quark model

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    Masses of the ground state light tetraquarks are dynamically calculated in the framework of the relativistic diquark-antidiquark picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark-gluon interaction in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV: f_0(600) (\sigma), K^*_0(800) (\kappa), f_0(980) and a_0(980) agree well with the light tetraquark interpretation.Comment: 9 pages, Report-no adde

    Coherent description of the intrinsic and extrinsic anomalous Hall effect in disordered alloys on an abab initioinitio level

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    A coherent description of the anomalous Hall effect (AHE) is presented that is applicable to pure as well as disordered alloy systems by treating all sources of the AHE on equal footing. This is achieved by an implementation of the Kubo-St\v{r}eda equation using the fully relativistic Korringa-Kohn-Rostoker (KKR) Green's function method in combination with the Coherent Potential Approximation (CPA) alloy theory. Applications to the pure elemental ferromagnets bcc-Fe and fcc-Ni led to results in full accordance with previous work. For the alloy systems fcc-Fex_xPd1−x_{1-x} and fcc-Nix_xPd1−x_{1-x} very satisfying agreement with experiment could be achieved for the anomalous Hall conductivity (AHC) over the whole range of concentration. To interpret these results an extension of the definition for the intrinsic AHC is suggested. Plotting the corresponding extrinsic AHC versus the longitudinal conductivity a linear relation is found in the dilute regimes, that allows a detailed discussion of the role of the skew and side-jump scattering processes.Comment: * shortened manuscript * slight rewordings * changed line style in Fig 1 * corrected misprinted S (skewness) factor * merged Fig. 3 with Fig. 1 * new citation introduce

    Ab-initio calculation of the Gilbert damping parameter via linear response formalism

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    A Kubo-Greenwood-like equation for the Gilbert damping parameter α\alpha is presented that is based on the linear response formalism. Its implementation using the fully relativistic Korringa-Kohn-Rostoker (KKR) band structure method in combination with Coherent Potential Approximation (CPA) alloy theory allows it to be applied to a wide range of situations. This is demonstrated with results obtained for the bcc alloy system Fex_xCo1−x_{1-x} as well as for a series of alloys of permalloy with 5d transition metals. To account for the thermal displacements of atoms as a scattering mechanism, an alloy-analogy model is introduced. The corresponding calculations for Ni correctly describe the rapid change of α\alpha when small amounts of substitutional Cu are introduced

    Bosonization in Particle Physics

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    Path integral techniques in collective fields are shown to be a useful analytical tool to reformulate a field theory defined in terms of microscopic quark (gluon) degrees of freedom as an effective theory of collective boson (meson) fields. For illustrations, the path integral bosonization approach is applied to derive a (non)linear sigma model from a Nambu-Jona-Lasinio (NJL) quark model. The method can be extended to include higher order derivative terms in meson fields or heavy-quark symmetries. It is also approximately applicable to QCD.Comment: 12 pages, LaTeX, uses lamuphys.sty, 5 LaTeX figures, talk given at the Workshop "Field Theoretical Tools in Polymer and Particle Physics", University Wuppertal, June 17-19, 199

    Mesons and diquarks in neutral color superconducting quark matter with β\beta-equilibrium

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    The spectrum of meson and diquark excitations in cold color-superconducting (2SC) quark matter is investigated under local color and electric neutrality constraints with β\beta-equilibrium. A 2-flavored Nambu--Jona-Lasinio type model including a baryon μB\mu_B, color μ8\mu_8, and electric μQ\mu_Q chemical potentials is used. Two relations between coupling constants HH and GG in the diquark- and quark-antiquark channels, correspondingly, are treated, H=3G/4H=3G/4 and H=GH=G. At H=3G/4H=3G/4 the gapless- and at H=GH=G the gapped neutral color superconductivity is realized. It is shown that color and electrical neutrality together with β\beta-equilibrium lead to a strong mass splitting within the pion isotriplet in the 2SC phase (both gapped and gapless), in contrast with non--neutral matter. It is also shown that the properties of the physical SU(2)cSU(2)_c-singlet diquark excitation in the 2SC ground state varies for different parameterization schemes. Thus, for H=3G/4H=3G/4 one finds a heavy resonance with mass ∼\sim 1100 MeV in the non--neutral (gapped) case, whereas, if neutrality is imposed, a stable diquark with mass ∼μQ∼\sim\mu_Q\sim 200 MeV appears in the gapless 2SC phase. For H=GH=G, there is again a resonance (with the mass ∼\sim 300 MeV) in the neutral gapped 2SC phase. Hence, the existence of the stable massive SU(2)c_c-singlet diquark excitation is a new peculiarity of the gapless 2SC.Comment: 18 pages, 9 figures; version accepted for publication in PR

    Diablo canyon power plant site ecological study Quarterly Report No. 1; July 1 - September 30, 1973

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    The second phase of ecological studies at the Diablo Canyon Power Plant site was initiated in July 1973. The first, phase conducted during 1970-71 involved baseline ecological surveys with special reference to abalone and bony fishes. The objectives of this second phase are to quantitativey monitor abalone and algal communities, including predators and competitors, along permanent intertidal and subtidal transects established during the first phase. During the quarter nine permanent transects were located and marked with new buoys. Surveys on seven of these transects were completed, and the commercial sea urchin and red abalone fisheries operating in the Diablo Cove area were monitored. Sea otter activities between Diablo Cove and Pt. Buchon were recorded to determine the location of the herd and their general food habits. Little evidence of feeding activity has been observed in Diablo Cove. Temperature tolerance studies, began in March 1973 on red abalones, were continued. Problems in obtaining viable abalone larvae hampered this project.(11pp.

    Diablo Canyon Power Plant site ecological study Quarterly Report No. 2; October 1 - December 31, 1973

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    During the period October 1 - December 31, 1973, Fall surveys of permanent subtidal stations were completed with one station being surveyed. We were unable to locate 3 subtidal stations. Intertidal studies were initiated in November. A total of 12 random stations was surveyed. Interviews were conducted with commercial abalone fishermen working between Pt. Buchon to Pecho Rock. We continued to monitor the sea otter herd foraging between Pt. Buchon and Lion Rock. Progress was achieved in the abalone temperature tolerance studies when a successful spawning occurred. (20pp.
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