261 research outputs found
Origin of G Magnetic Fields in the Central Engine of Gamma Ray Bursts
Various authors have suggested that the gamma-ray burst (GRB) central engine
is a rapidly rotating, strongly magnetized, G) compact
object. The strong magnetic field can accelerate and collimate the relativistic
flow and the rotation of the compact object can be the energy source of the
GRB. The major problem in this scenario is the difficulty of finding an
astrophysical mechanism for obtaining such intense fields. Whereas, in
principle, a neutron star could maintain such strong fields, it is difficult to
justify a scenario for their creation. If the compact object is a black hole,
the problem is more difficult since, according to general relativity it has "no
hair" (i.e., no magnetic field). Schuster, Blackett, Pauli, and others have
suggested that a rotating neutral body can create a magnetic field by
non-minimal gravitational-electromagnetic coupling (NMGEC). The
Schuster-Blackett form of NMGEC was obtained from the Mikhail and Wanas's
tetrad theory of gravitation (MW). We call the general theory NMGEC-MW.
We investigate here the possible origin of the intense magnetic fields G in GRBs by NMGEC-MW. Whereas these fields are difficult to
explain astrophysically, we find that they are easily explained by NMGEC-MW. It
not only explains the origin of the G fields when the
compact object is a neutron star, but also when it is a black hole.Comment: 9 pages, accepted for publication in JCA
Inter-relation between soybean yield and soil compaction under degraded pasture in Brazilian Savannah
Estimativa da radiação global incidente em superfÃcies inclinadas por modelos isotrópicos e Ãndice de claridade
Physical properties and particle-size fractions of soil organic matter in crop-livestock integration
Screening, production and biochemical characterization of a new fibrinolytic enzyme produced by Streptomyces sp. (Streptomycetaceae) isolated from Amazonian lichens
Thrombosis is a pathophysiological disorder caused by accumulation of fibrin in the blood. Fibrinolytic proteases with potent thrombolytic activity have been produced by diverse microbial sources. Considering the microbial biodiversity of the Amazon region, this study aimed at the screening, production and biochemical characterization of a fibrinolytic enzyme produced by Streptomyces sp. isolated from Amazonian lichens. The strain Streptomyces DPUA1576 showed the highest fibrinolytic activity, which was 283 mm2. Three variables at two levels were used to assess their effects on the fibrinolytic production. The parameters studied were agitation (0.28 - 1.12 g), temperature (28 - 36 ºC) and pH (6.0 - 8.0); all of them had significant effects on the fibrinolytic production. The maximum fibrinolytic activity (304 mm2) was observed at 1.12 g, 28 ºC, and pH of 8.0. The crude extract of the fermentation broth was used to assess the biochemical properties of the enzyme. Protease and fibrinolytic activities were stable during 6 h, at a pH ranging from 6.8 to 8.4 and 5.8 to 9.2, respectively. Optimum temperature for protease activity ranged between 35 and 55 °C, while the highest fibrinolytic activity was observed at 45 ºC. Proteolytic activity was inhibited by Cu2+ and Co2+ ions, phenylmethylsulfonyl fluoride (PMSF) and pepstatin A, which suggests that the enzyme is a serine protease. Enzymatic extract cleaved fibrinogen at the subunits A-chain, A-chain, and -chain. The results indicated that Streptomyces sp. DPUA 1576 produces enzymes with fibrinolytic and fibrinogenolytic activity, enzymes with an important application in the pharmaceutical industry.The authors grateful acknowledge the financial support of Fundação de Amparo a Pesquisa do Estado de Pernambuco (FACEPE, Pernambuco, Brazil, N. 0158-2.12/11), CNPq/ RENORBIO (National Counsel of Technological and Scientific Development, N.55146/2010-3) and National Council for the Improvement of Higher Education (CAPES, Brazil) for the scholarship. The author thanks editor and reviewers for their review and comments.info:eu-repo/semantics/publishedVersio
Produtividade da soja correlacionada com a porosidade e a densidade de um Latossolo Vermelho do cerrado brasileiro
Intake, performance and nutrient digestibility of sheep fed sugarcane treated and ensiled with calcium oxide or urea
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