Weak Mirror Symmetry of Complex Symplectic Algebras

A complex symplectic structure on a Lie algebra \lie h is an integrable complex structure $J$ with a closed non-degenerate $(2,0)$-form. It is determined by $J$ and the real part $\Omega$ of the $(2,0)$-form. Suppose that \lie h is a semi-direct product \lie g\ltimes V, and both \lie g and $V$ are Lagrangian with respect to $\Omega$ and totally real with respect to $J$. This note shows that \lie g\ltimes V is its own weak mirror image in the sense that the associated differential Gerstenhaber algebras controlling the extended deformations of $\Omega$ and $J$ are isomorphic. The geometry of $(\Omega, J)$ on the semi-direct product \lie g\ltimes V is also shown to be equivalent to that of a torsion-free flat symplectic connection on the Lie algebra \lie g. By further exploring a relation between $(J, \Omega)$ with hypersymplectic algebras, we find an inductive process to build families of complex symplectic algebras of dimension $8n$ from the data of the $4n$-dimensional ones.Comment: 22 page

Curvature decomposition of G_2 manifolds

Explicit formulas for the $G_2$-components of the Riemannian curvature tensor on a manifold with a $G_2$ structure are given in terms of Ricci contractions. We define a conformally invariant Ricci-type tensor that determines the 27-dimensional part of the Weyl tensor and show that its vanishing on compact $G_2$ manifold with closed fundamental form forces the three-form to be parallel. A topological obstruction for the existence of a $G_2$ structure with closed fundamental form is obtained in terms of the integral norms of the curvature components. We produce integral inequalities for closed $G_2$ manifold and investigate limiting cases. We make a study of warped products and cohomogeneity-one $G_2$ manifolds. As a consequence every Fern\'andez-Gray type of $G_2$ structure whose scalar curvature vanishes may be realized such that the metric has holonomy contained in $G_2$.Comment: LaTeX 2e, 26 pages, 2 tables. Changes in version 2: shortened, reorganized, misprints corrected, several remarks and new introduction. A formula in the proof of Theorem 1.2a has been corrected. Submitte

Pesquisadores e suas táticas discursivas no debate sobre populaç��es tradicionais e proteção à biodiversidade

The debate over the relationship between biodiversity and traditional populations today is much divided. Such a polarized atmosphere is expressed in the interface that marks the researchers’ scientific workand political action around the subject. As I argue, one of the effects of this phenomenon has been the crystallization of a general controversy: on the one hand, a search for evidence from those who support the thesis that traditional peoples always vandalized nature; on the other hand, a similar effort from scientists that look for evidence to prove that these peoples protect biodiversity. As a result, we have a debate in which scientists and their research become very powerful weapons of persuasion. Like in a trial, their researches are used to prosecute or defend traditional populations and/or protected areas, which play the part of defendants or victims. As a result, experts who invest in this discussion are often called on to make argumentative choices. These argumentative choices are the main point of this article. Aiming at accessing the universe of expert discourse on policies in support of traditional populations and stricter policies to protect biodiversity, I will then take the antagonisms that emerge as a laboratory for observing the dynamics of arguments and counterarguments that follow. Finally, I question the possibility that in discussing the issue from the logic of “either/or” (traditional populations either “save” or “destroy” biodiversity) chances are that the endless disputes for either party lead to an analytically barren controversy without answers

A incidência de broncoaspiração e o impacto da prevenção em pacientes internados em um hospital terciário. / The incidence of bronchoaspiration and the impact of prevention in patients admitted to a tertiary care hospital.

A broncoaspiração é considerada o evento adverso que mais agrava o quadro clínico do paciente disfágico. Pode aumentar tempo de internação, custo para o sistema de saúde e possibilidade de óbito do paciente. O presente estudo, pretendeu avaliar a incidência de broncoaspiração em indivíduos internados num hospital terciário no período de um ano, bem como os efeitos das medidas preventivas. A pesquisa foi de caráter longitudinal e retrospectivo. Dentre os 16.242 indivíduos  admitidos na unidade durante um ano, 11.041 (68,0%)  apresentaram risco para broncoaspiração. Estes pacientes passaram por avaliação fonoaudiológica para determinação da presença do quadro aspirativo. 26 indivíduos incluídos neste estudo, a maioria era do sexo masculino e apresentaram o episódio broncoaspiração durante o período de internação hospitalar. As doenças de base mais frequentes nestas pessoas foram as de origem neurológica e oncológicos. Em relação a via de alimentação, grande parte era nutrido por via oral e enteral.  14 (53,8%) passaram a utilizar via alternativa de alimentação e em 18 (69,2%) participantes a broncoaspiração se deu pela presença de vômito. Há elevada prevalência de risco de broncoaspiração, com maior prevalência em idosos, cuja doença de base tem origem neurológica. A maior causa de broncoaspiração nestes pacientes foi o vômito e o óbito foi apontado como um desfecho prevalente. As medidas intra-hospitalares de prevenção contribuíram para a prevenção da broncoaspiração