2,026 research outputs found
Some observations on the reproductive biology of the sixgill shark Hexanchus griseus (Bonnaterre, 1788) from South African waters
Observations are made of the maturation status of 81 male and 88 female sixgill sharks Hexanchus griseus from southern African waters. Males mature at about 310 cm total length (TL) with the calcification of the terminal cartilage elements of the claspers. Determination of maturity for females was problematic, but most were fully mature by at least 420 cm TL. Newborns were captured at the same location over three consecutive summer seasons, indicating the location of a possible pupping ground.Keywords: maturity size, pupping grounds, reproduction, sixgill sharksAfrican Journal of Marine Science 2002, 24: 359–36
First records of the longnose spiny dogfish Squalus blainvillei (Squalidae) and the deep-water stingray Plesiobatis daviesi (Urolophidae) from South African waters
Deep-set longline investigations of the slope waters off northern KwaZulu-Natal on the east coast of South Africa confirmed the first records of the longnose spiny dogfish Squalus blainvillei (Squalidae) and the deepwater stingray Plesiobatis daviesi (Urolophidae) from South African waters.Keywords: first records, Plesiobatis daviesi, Squalus blainvillei, South AfricaAfrican Journal of Marine Science 2002, 24: 355–35
B=1 Soliton of the Nambu - Jona-Lasinio model in medium}
The solitonic sector of the Nambu - Jona-Lasinio model with baryon number one
is solved in the presence of an external medium. The calculations fully include
the polarization of both the Dirac sea and the medium as well as the Pauli
blocking effect. We found that with an increasing density the medium
destabilizes the soliton. At finite medium density the soliton mass gets
reduced whereas the mean square baryon radius shows an increase - a swelling of
the soliton. At some critical density of about two times nuclear matter density
there is no localized solution - the soliton disappears.Comment: PHYSTEX, 14 pages, 5 figures (available upon request), Preprint
RUB-TPII-26/9
Revision of the genus Centrophorus (Squaliformes: Centrophoridae): Part 1-Redescription of Centrophorus granulosus (Bloch & Schneider), a senior synonym of C-acus Garman and C-niaukang Teng
The genus Centrophorus is one of the most taxonomically complex and confusing elasmobranch groups. A revision of this group is currently underway and this first paper sets an important foundation in this process by redescribing the type species of the genus-Centrophorus granulosus. This taxon name has been previously applied to two different morphotypes: a large species \u3e 1.5 m TL and a smaller species similar to 1 m TL. Centrophorus acus and C. niaukang are the most commonly used names applied to the larger morphotype. The original description of C. granulosus was based on a large specimen of similar to 1.5 m TL, but subsequent redescriptions were based on either of the large or small morphotypes. Centrophorus granulosus is herein redescribed as a large species and a neotype is designated. Centrophorus acus and C. niaukang are found to be junior synonyms of C. granulosus. Centrophorus granulosus is distinguishable from its congeners by its large size, dermal denticle shape, colouration and a number of morphological and biological characteristics. Ontogenetic changes in morphology, dentition and denticle shape for this species are described in detail
Dynamical chiral symmetry breaking by a magnetic field and multi-quark interactions
Catalysis of dynamical symmetry breaking by a constant magnetic field in
(3+1) dimensions is considered. We use the three flavour Nambu -- Jona-Lasinio
type model with 't Hooft and eight-quark interaction terms. It is shown that
the multi-quark interactions introduce new additional features to this
phenomenon: (a) the local minimum of the effective potential catalyzed by the
constant magnetic field is smoothed out with increasing strength of the field
at the characteristic scale H~10^{19} G, (b) the multi-quark forces generate
independently another local minimum associated with a larger dynamical fermion
mass. This state may exist even for multi-quark interactions with a subcritical
set of couplings, and is globally stable with respect to a further increase of
the magnetic field.Comment: 6 pages, 3 figures, added discussion and references, version to
appear in Phys.Lett.
Mães de crianças com transtorno autÃstico: percepções e trajetórias
O autismo infantil caracteriza-se por comprometimento grave e global em diversas áreas do desenvolvimento humano, o que gera ampla demanda de cuidados e dependência dos pais. Objetivou-se conhecer as percepções de mães de crianças com autismo quanto à s alterações apresentadas pelo filho e suas trajetórias percorridas na busca pelo diagnóstico de autismo. Trata-se de um estudo exploratório, descritivo, com abordagem qualitativa, no qual participaram dez mães. A coleta de dados ocorreu em 2013, com entrevistas semiestruturadas. Da análise de conteúdo temática emergiram as categorias: percepções de mães quanto a alterações no comportamento e/ou desenvolvimento de seus filhos; e trajetórias das mães na busca pelo diagnóstico do filho. Após a percepção das alterações no comportamento/desenvolvimento, as mães enfrentam uma peregrinação pelos serviços de saúde
A presença da Psicologia nas teses e dissertações dos cursos de pós-graduação da Faculdade de Educação da UFRGS
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Morphological Characters of the Thickbody Skate Amblyraja frerichsi (Krefft 1968) (Rajiformes: Rajidae), with Notes on Its Biology
Detailed descriptions of morphological features, morphometrics, neurocranium anatomy, clasper structure and egg case descriptions are provided for the thickbody skate Amblyraja frerichsi; a rare, deep-water species from Chile, Argentina and Falkland Islands. The species diagnosis is complemented from new observations and aspects such as colour, size and distribution are described. Geographic and bathymetric distributional ranges are discussed as relevant features of this taxońs biology. Additionally, the conservation status is assessed including bycatch records from Chilean fisheries
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