111 research outputs found
Genera Euastrum Ehrenberg ex Ralfs and Micrasterias C.Agardh (Conjugatophyceae-Desmidiaceae) from two Amazon black water environments (Manaus,Amazonas-Brazil)
An investigation of genera Euastrum Ehrenberg ex Ralfs and Micrasterias C.Agardh from an Amazon floodplain lake of the Negro river Basin was undertaken. The samples were collected using a plankton net in four stations on the Tupe Lake and one station near a lake on the Negro river. The species were identified and described on the basis of morphological and morphometrical characteristics. A total of 12 species were identified, five species of Euastrum genus (E. evolutum var. perornatum; E. gemmatum var. monocyclum; E. ornans; E. sinuosum; E. spinulosum), and seven of Micrasterias genus (M. borgei; M. radiata var. brasiliensis; M. torreyi; M. laticeps var. acuminata; M. mahabuleshwarensis var. amazonensis; M. rotata var. rotata; M. siolii). All species, except M. radiata Hassal var. brasiliensis Grönblad, were found in the Negro river; on the other hand, only seven species were found in the TupĂ© lake, three of Euastrum and four of Micrasterias.Foi realizado um inventĂĄrio das espĂ©cies dos gĂȘneros Euastrum Ehrenberg ex Ralfs e Micrasterias C.Agardh de dois ambientes de ĂĄguas pretas do municĂpio de Manaus, um lago de inundação (lago TupĂ©), e o rio Negro. As coletas foram realizadas com rede de plĂąncton em quatro estaçÔes no lago e uma no rio Negro, situada prĂłxima ao lago. Um total de 93 amostras foi analisado, coletadas em escala mensal no perĂodo de março de 2002 a outubro de 2003. As espĂ©cies foram descritas e ilustradas com base na sua morfologia e morfometria. Um total de 12 espĂ©cies foi identificado, sendo cinco do gĂȘnero Euastrum (E. evolutum var. perornatum; E. gemmatum var. monocyclum; E. ornans; E. sinuosum e E. spinulosum), e sete do gĂȘnero Micrasterias (M. borgei; M. radiata var. brasiliensis; M. torreyi; M. laticeps var. acuminata; M. mahabuleshwarensis var. amazonensis; M. rotata var. rotata; M. siolii). Todas as espĂ©cies, exceto M. radiata Hassal var. brasiliensis Grönblad, foram registradas no rio Negro, enquanto no lago TupĂ© foi registrado, no geral, apenas sete espĂ©cies, trĂȘs de Euastrum e quatro de Micrasterias
Four-dimensional anti-de Sitter black holes from a three-dimensional perspective: Full complexity
The dimensional reduction of black hole solutions in four-dimensional (4D)
general relativity is performed and new 3D black hole solutions are obtained.
Considering a 4D spacetime with one spacelike Killing vector, it is possible to
split the Einstein-Hilbert-Maxwell action with a cosmological term in terms of
3D quantities. Definitions of quasilocal mass and charges in 3D spacetimes are
reviewed. The analysis is then particularized to the toroidal charged rotating
anti-de Sitter black hole. The reinterpretation of the fields and charges in
terms of a three-dimensional point of view is given in each case, and the
causal structure analyzed.Comment: 26 pages, 1 figure, Uses revtex
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