Constraints on the Pion-Nucleus Optical Potential from the (p,pi) Reaction

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Energy Dependence of the NN t-matrix in the Optical Potential for Elastic Nucleon-Nucleus Scattering

The influence of the energy dependence of the free NN t-matrix on the optical potential of nucleon-nucleus elastic scattering is investigated within the context of a full-folding model based on the impulse approximation. The treatment of the pole structure of the NN t-matrix, which has to be taken into account when integrating to negative energies is described in detail. We calculate proton-nucleus elastic scattering observables for $^{16}$O, $^{40}$Ca, and $^{208}$Pb between 65 and 200 MeV laboratory energy and study the effect of the energy dependence of the NN t-matrix. We compare this result with experiment and with calculations where the center-of-mass energy of the NN t-matrix is fixed at half the projectile energy. It is found that around 200 MeV the fixed energy approximation is a very good representation of the full calculation, however deviations occur when going to lower energies (65 MeV).Comment: 11 pages (revtex), 6 postscript figure

Bycatch of franciscana dolphins Pontoporia blainvillei and the dynamic of artisanal fisheries in the species' southernmost area of distribution

Na Argentina, a toninha é um dos cetáceos mais vulneráveis devido às capturas por rede de pesca artesanal. O presente estudo teve como objetivo estimar as capturas acidentais no sul da província de Buenos Aires, através de entrevistas aos capitães de barcos de pesca artesanal, entre os anos 2006-2009. As capturas foram reportadas para redes de emalhe e de camarão; com as mais altas frequências entre outubro e fevereiro, a 5 km da costa e 10-20 m de profundidade. A mortalidade acidental média anual estimada foi de 107 golfinhos (IC 95% = 87-129), 92 em redes de emalhe (IC 95% = 73-112) e 15 em redes de camarão (IC 95% = 8-25), com uma captura de 0,029 golfinhos/km de rede de emalhe (IC 95% = 0,023-0,036) e 0,024/rede de camarão (IC 95% = 0,012-0,035). As flutuações anuais responderam principalmente às diferenças nos dias de pesca. Considerando o último levantamento estimativo feito para o norte costeiro da província, estima-se uma mortalidade entre 360-539 golfinhos/ano em toda a província de Buenos Aires. Esses valores correspondem de 2,5-3,7% da abundância populacional da Argentina; o que traria como consequência um declínio populacional da espécie, tornando-se fundamental encontrar alternativas de pesca para a área.In Argentina, the franciscana dolphin is one of the most vulnerable cetaceans regularly entangled in coastal artisanal fishery nets. The aim of this paper is to estimate the species' incidental mortality on the Southern coast of Buenos Aires province through interviews with the captains of artisanal fishing vessels, in the period 2006-2009. Franciscana bycatch was reported for gillnets and shrimper gear all year round but it occurred more frequently between October and February, at 5 km offshore and 10-20 m depth. The estimated mean annual incidental mortality was 107 dolphins (CI 95% = 87-129), 92 caught in gillnets (CI 95% = 73-112) and 15 in shrimpers' gear (CI 95% = 8-25) with a capture per unit effort of 0.029 dolphins per km of gillnet (CI 95% = 0.023-0.036) and 0.022 per shrimpe r's net (CI 95% = 0.012-0.035). Annual fluctuations were due to differences in the number of gillnetting fishing days. If mortality estimates for the Northern coast are also taken into account, values attain a maximum of 360-539 dolphins bycaught in the entire Buenos Aires province, representing 2.5-3.7% of the species' abundance in Argentina. This will inevitably lead to the decline of franciscana dolphin populations in the near future unless alternative fishing grounds are identified and alternative gearadopted

Development of nuclear models for higher energy calculations

Two nuclear models for higher energy calculations have been developed in the regions of high and low energy transfer, respectively. In the former, a relativistic hybrid-type preequilibrium model is compared with data ranging from 60 to 800 MeV. Also, the GNASH exciton preequilibrium-model code with higher energy improvements is compared with data at 200 and 318 MeV. In the region of low energy transfer, nucleon-nucleus scattering is predominately a direct reaction involving quasi-elastic collisions with one or more target nucleons. We discuss various aspects of quasi-elastic scattering which are important in understanding features of cross sections and spin observables. These include (1) contributions from multi-step processes; (2) damping of the continuum response from 2p-2h excitations; (3) the ''optimal'' choice of frame in which to evaluate the nucleon-nucleon amplitudes; and (4) the effect of optical and spin-orbit distortions, which are included in a model based on the RPA the DWIA and the eikonal approximation. 33 refs., 15 figs

Sightings of franciscana dolphins (pontoporia blainvillei): the discovery of a population in the Paranaguá estuarine complex, Southern Brazil

Submitted by Guilherme Lemeszenski ([email protected]) on 2013-08-22T18:43:45Z No. of bitstreams: 1 S1679-87592009000100006.pdf: 999687 bytes, checksum: ec72a0f80ee9b16f18b9ef407272949e (MD5)Made available in DSpace on 2013-08-22T18:43:45Z (GMT). No. of bitstreams: 1 S1679-87592009000100006.pdf: 999687 bytes, checksum: ec72a0f80ee9b16f18b9ef407272949e (MD5) Previous issue date: 2009-03-01Made available in DSpace on 2013-09-30T19:31:36Z (GMT). No. of bitstreams: 2 S1679-87592009000100006.pdf: 999687 bytes, checksum: ec72a0f80ee9b16f18b9ef407272949e (MD5) S1679-87592009000100006.pdf.txt: 23630 bytes, checksum: 40f2ef6e6f7220229634a1173c194406 (MD5) Previous issue date: 2009-03-01Submitted by Vitor Silverio Rodrigues ([email protected]) on 2014-05-20T15:08:38Z No. of bitstreams: 2 S1679-87592009000100006.pdf: 999687 bytes, checksum: ec72a0f80ee9b16f18b9ef407272949e (MD5) S1679-87592009000100006.pdf.txt: 23630 bytes, checksum: 40f2ef6e6f7220229634a1173c194406 (MD5)Made available in DSpace on 2014-05-20T15:08:38Z (GMT). No. of bitstreams: 2 S1679-87592009000100006.pdf: 999687 bytes, checksum: ec72a0f80ee9b16f18b9ef407272949e (MD5) S1679-87592009000100006.pdf.txt: 23630 bytes, checksum: 40f2ef6e6f7220229634a1173c194406 (MD5) Previous issue date: 2009-03-01Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências Departamento de ZoologiaUniversidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências Departamento de ZoologiaFAPESP: 05/59439-5FAPESP: 05/54149-

On the recommended vernacular names of <i>Mesoplodon peruvianus</i> Reyes, Mead & Van Waerebeek, 1991 (Cetacea, Ziphiidae) in several world languages

Relevant and distinctive vernacular species names are essential to assure efficient communication among scientists under field and laboratory conditions, but also among non-specialists including the public at large. We provide a rationale for recommended vernacular and alternative names for the lesser beaked whale Mesoplodon peruvianus Reyes, Mead & Van Waerebeek, 1991 in 11 major world languages which encompass most of cetacean literature. Principal criteria for name endorsement are unambiguity and nonrepetitiveness with respect to other aquatic mammal species