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Search Results: 1 - 10 of 2942 matches for " Albuquerque "
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Escherichia coli in seafood: A brief overview  [PDF]
Renata Albuquerque Costa
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.43A060
Abstract:

Considering the importance of researching the bacteriological quality of seafood, the following study aimed to make a brief overview on the occurrence of Escherichia coli in marine fish and shellfish, and to discuss the sanitary importance that the isolation of this enterobacteria represents to public health.

Resenha: Shozo Motoyama (org.) - Prelúdio para uma História: Ciência e Tecnologia no Brasil
Rui Albuquerque
Revista Brasileira de Inova??o , 2005,
Abstract:
From dropout to continuation in a higher education course
Teresa Albuquerque
Sísifo : Educational Sciences Journal , 2008,
Abstract: The study set out to ascertain how students, who begin a Higher Education course which is not their first option, adapt to the Faculty and why they do not drop out.Data was obtained by means of questionnaires and semi-structured interviews given to students who had entered Higher Education for the first time in 2004/2005.The findings indicated that students began to understand the profession, the type of population they are likely to work with and the type of work they may perform through the practical academic activities carried out during the course. Student involvement in the course and their pedagogical relationship were seen to be the most important factors in their decision to stay on the course.
Remarks on symplectic twistor spaces
Rui Albuquerque
Mathematics , 2007, DOI: 10.1007/s10231-008-0082-5
Abstract: We consider some classical fibre bundles furnished with almost complex structures of twistor type, deduce their integrability in some cases and study \textit{self-holomorphic} sections of a \textit{symplectic} twistor space. With these we define a moduli space of $\omega$-compatible complex structures. We recall the theory of flag manifolds in order to study the Siegel domain and other domains alike, which is the fibre of the referred twistor space. Finally the structure equations for the twistor of a Riemann surface with the canonical symplectic-metric connection are deduced, based on a given conformal coordinate on the surface. We then relate with the moduli space defined previously.
Homotheties and topology of tangent sphere bundles
Rui Albuquerque
Mathematics , 2010,
Abstract: We prove a Theorem on homotheties between two given tangent sphere bundles $S_rM$ of a Riemannian manifold $M,g$ of $\dim\geq 3$, assuming different variable radius functions $r$ and weighted Sasaki metrics induced by the conformal class of $g$. New examples are shown of manifolds with constant positive or with constant negative scalar curvature, which are not Einstein. Recalling results on the associated almost complex structure $I^G$ and symplectic structure ${\omega}^G$ on the manifold $TM$, generalizing the well-known structure of Sasaki by admitting weights and connections with torsion, we compute the Chern and the Stiefel-Whitney characteristic classes of the manifolds $TM$ and $S_rM$.
Weighted metrics on tangent sphere bundles
Rui Albuquerque
Mathematics , 2010, DOI: 10.1093/qmath/haq051
Abstract: Natural metric structures on the tangent bundle and tangent sphere bundles $S_rM$ of a Riemannian manifold $M$ with radius function $r$ enclose many important unsolved problems. Admitting metric connections on $M$ with torsion, we deduce the equations of induced metric connections on those bundles. Then the equations of reducibility of $TM$ to the almost Hermitian category. Our purpose is the study of the natural contact structure on $S_rM$ and the $G_2$-twistor space of any oriented Riemannian 4-manifold.
Variations of gwistor space
Rui Albuquerque
Mathematics , 2011, DOI: 10.4171/PM/1929
Abstract: We study natural variations of the G2 structure {\sigma}_0 \in {\Lambda}^3_+ existing on the unit tangent sphere bundle SM of any oriented Riemannian 4-manifold M. We find a circle of structures for which the induced metric is the usual one, the so-called Sasaki metric, and prove how the original structure has a preferred role in the theory. We deduce the equations of calibration and cocalibration, as well as those of W3 pure type and nearly-parallel type.
On the characteristic connection of gwistor space
Rui Albuquerque
Mathematics , 2011, DOI: 10.2478/s11533-012-0082-y
Abstract: We give a brief presentation of gwistor space, which is a new concept from G_2 geometry. Then we compute the characteristic torsion T^c of the gwistor space of an oriented Riemannian 4-manifold with constant sectional curvature k and deduce the condition under which T^c is \nabla^c-parallel; this allows for the classification of the G_2 structure with torsion and the characteristic holonomy according to known references. The case with the Einstein base manifold is envisaged.
Curvatures of weighted metrics on tangent sphere bundles
Rui Albuquerque
Mathematics , 2011,
Abstract: We determine the curvature equations of natural metrics on tangent bundles and radius r tangent sphere bundles S_rM of a Riemannian manifold M. A family of positive scalar curvature metrics on S_rM is found, for any M with bounded sectional curvature and any chosen constant r.
On vector bundle manifolds with spherically symmetric metrics
Rui Albuquerque
Mathematics , 2014,
Abstract: We give a general description of the construction of weighted spherically symmetric metrics on vector bundle manifolds, i.e. the total space of a vector bundle $E\longrightarrow M$, over a Riemannian manifold $M$, when $E$ is endowed with a metric connection. The tangent bundle of $E$ admits a canonical decomposition and thus it is possible to define an interesting class of `two weights' metrics with such weight functions depending on the fibre norm of $E$; hence the generalized concept of spherically symmetric metrics. We study its main properties and curvature equations. Finally we compute the holonomy of Bryant-Salamon type $\mathrm{G}_2$ manifolds.
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