Improving methods in gap ecology: Revisiting size and shape distributions using a model selection approach

Questions: We assess gap size and shape distributions, two important descriptors of the forest disturbance regime, by asking: which statistical model best describes gap size distribution; can simple geometric forms adequately describe gap shape; does gap size or shape vary with forest type, gap age or the method used for gap delimitation; and how similar are the studied forests and other tropical and temperate forests? Location: Southeastern Atlantic Forest, Brazil. Methods: Analysing over 150 gaps in two distinct forest types (seasonal and rain forests), a model selection framework was used to select appropriate probability distributions and functions to describe gap size and gap shape. The first was described using univariate probability distributions, whereas the latter was assessed based on the gap area-perimeter relationship. Comparisons of gap size and shape between sites, as well as size and age classes were then made based on the likelihood of models having different assumptions for the values of their parameters. Results: The log-normal distribution was the best descriptor of gap size distribution, independently of the forest type or gap delimitation method. Because gaps became more irregular as they increased in size, all geometric forms (triangle, rectangle and ellipse) were poor descriptors of gap shape. Only when small and large gaps (> 100 or 400m2 depending on the delimitation method) were treated separately did the rectangle and isosceles triangle become accurate predictors of gap shape. Ellipsoidal shapes were poor descriptors. At both sites, gaps were at least 50% longer than they were wide, a finding with important implications for gap microclimate (e.g. light entrance regime) and, consequently, for gap regeneration. Conclusions: In addition to more appropriate descriptions of gap size and shape, the model selection framework used here efficiently provided a means by which to compare the patterns of two different types of forest. With this framework we were able to recommend the log-normal parameters μ and σ for future comparisons of gap size distribution, and to propose possible mechanisms related to random rates of gap expansion and closure. We also showed that gap shape varied highly and that no single geometric form was able to predict the shape of all gaps, the ellipse in particular should no longer be used as a standard gap shape. © 2012 International Association for Vegetation Science.

Strain- and electric field-induced band gap modulation in nitride nanomembranes

The hexagonal nanomembranes of the group III-nitrides are a subject of interest due to their novel technological applications. In this paper, we investigate the strain- and electric field-induced modulation of their band gaps in the framework of density functional theory. For AlN, the field-dependent modulation of the bandgap is found to be significant whereas the strain-induced semiconductor-metal transition is predicted for GaN. A relatively flat conduction band in AlN and GaN nanomembranes leads to an enhancement of their electronic mobility compared to that of their bulk counterparts. © 2013 IOP Publishing Ltd.

A success in Toxinology translational research in Brazil: Bridging the gap

Basic research is fundamental for discovering potential diagnostic and therapeutic tools, including drugs, vaccines and new diagnostic techniques. On this basis, diagnosis and treatment methods for many diseases have been developed. Presently, discovering new candidate molecules and testing them in animals are relatively easy tasks that require modest resources and responsibility. However, crossing the animal-to-human barrier is still a great challenge that most researchers tend to avoid. Thus, bridging this current gap between clinical and basic research must be encouraged and elucidated in training programmes for health professionals. This project clearly shows the challenges faced by a group of Brazilian researchers who, after discovering a new fibrin sealant through 20 years of painstaking basic work, insisted on having the product applied clinically. The Brazilian government has recently become aware of this challenge and has accordingly defined the product as strategic to the public health of the country. Thus, in addition to financing research and development laboratories, resources were invested in clinical trials and in the development of a virtual platform termed the Virtual System to Support Clinical Research (SAVPC); this platform imparts speed, reliability and visibility to advances in product development, fostering interactions among sponsors, physicians, students and, ultimately, the research subjects themselves. This pioneering project may become a future model for other public institutions in Brazil, principally in overcoming neglected diseases, which unfortunately continue to afflict this tropical country. © 2013 Elsevier Ltd.

Gap solitons in a spin-orbit-coupled bose-einstein condensate

We report a diversity of stable gap solitons in a spin-orbit-coupled Bose-Einstein condensate subject to a spatially periodic Zeeman field. It is shown that the solitons can be classified by the main physical symmetries they obey, i.e., symmetries with respect to parity (P), time (T), and internal degree of freedom, i.e., spin (C), inversions. The conventional gap and gap-stripe solitons are obtained in lattices with different parameters. It is shown that solitons of the same type but obeying different symmetries can exist in the same lattice at different spatial locations. PT and CPT symmetric solitons have antiferromagnetic structure and are characterized, respectively, by nonzero and zero total magnetizations. © 2013 American Physical Society.

Implant-abutment gap versus microbial colonization: Clinical significance based on a literature review

Microorganisms from the oral cavity may settle at the implant-abutment interface (IAI). As a result, tissue inflammation could occur around these structures. The databases MEDLINE/PubMed and PubMed Central were used to identify articles published from 1981 through 2012 related to the microbial colonization in the implant-abutment gap and its consequence in terms of crest bone loss and osseointegration. The following considerations could be put forward, with respect to the clinical importance of IAI: (a) the space present at the IAI seems to allow bacterial leakage to occur, in spite of the size of this space; (b) bacterial leakage seems to occur at the IAI, irrespective of the type of connection. More studies are necessary to clarify the relationship between leakage at IAI and abutment connection designs; (c) losses at the peri-implant bone crests cannot be related to the IAI size, since few studies have shown no relationship. Also, the microbial leakage at the IAI cannot be related to the bone crest loss, since there are no articles reporting this relationship; remains controversial the influence of the IAI position on the bone crest losses. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 1321-1328, 2013. Copyright © 2013 Wiley Periodicals, Inc.

Dynamical chiral symmetry breaking: the fermionic gap equation with dynamical gluon mass and confinement

Pós-graduação em Física - IFT

The Transport and Trade Infrastructure Growth Gap in Latin America

This edition of the FAL Bulletin addresses the topic of transport infrastructure growth and its relationship to trade in Latin America. This study, examining the cases of four Latin American countries.

The economic infrastructure gap in Latin America and the Caribbean

This edition of the FAL Bulletin analyzes the impact of economic infrastructure on development in Latin America and the Caribbean and looks at future investment needs for 2006-2020. It reviews the specialized literature and updates the statistical information available on public and private investment in developing economic infrastructure in some countries in the region.

Inequality in education in Costa Rica: The gap between students in public and private schools. An analysis of the results of the Programme for International Student Assessment (PISA)

Includes bibliography.

The economic infrastructure gap and investment in Latin America

This edition of the FAL Bulletin aims to present and encourage the use of the economic infrastructure investment database for Latin America and the Caribbean (EII-LAC-DB), built by the Infrastructure Services Unit of the Economic Commission for Latin America and the Caribbean (ECLAC). The information contained refers to the period 1980-2012, in keeping with measurements undertaken by the World Bank, ECLAC and under the cooperation agreement between ECLAC and the Development Bank of Latin America (CAF).

The equity gap: Latin America, the Caribbean and the Social Summit

The World Summit for Social Development, held in Copenhagen, Denmark, from 6 to 12 March 1995, brought together a large number of heads of State and Government and official representatives from States Members of the United Nations and culminated in the adoption of the Copenhagen Declaration on Social Development and the Programme of Action of the World Summit for Social Development. These two documents —the first containing policy statements, the other dealing with their practical application— imply commitments at the national, regional and international levels. Barely two years have passed since this summit was held, too short a period to permit an evaluation of the impact of the actions that the Latin American and Caribbean Governments set out to undertake. On the other hand, most of the countries were already implementing a variety of official policies related to the great objectives of the World Summit for Social Development. Al reunirse ahora los países miembros de la CEPAL para examinar, por vez primera, los avances hacia la aplicación de los resultados de la Cumbre,1 la Secretaría ha centrado su estudio en tres aspectos. Primero, en examinar, desde la óptica latinoamericana y del Caribe, la situación actual en materia de pobreza, empleo e integración social, los principales temas de la Cumbre. Segundo, en el ámbito de las políticas, en reseñar las tendencias que resultan más relevantes para el cumplimiento de los compromisos antes mencionados. Tercero, en proponer algunas orientaciones adicionales sobre el contenido y alcance de las políticas tendientes a facilitar el pleno cumplimiento futuro de dichos compromisos. Se procura con ello orientar el debate de los gobiernos y de la sociedad civil en América Latina y el Caribe acerca de cómo se están instrumentando en la región los compromisos de la Cumbre de Copenhague.

A gap analysis of ornithological research in the brazilian state of Roraima

Neste artigo, o esforço de investigação ornitológica no estado de Roraima será investigado utilizando abordagens de análises de lacunas. Basicamente, apresentaremos uma síntese sobre todo o esforço ornitológico feito até o momento em Roraima, visando responder as seguintes questões: (a) quais os locais bem amostrados para aves? (b) quais são as lacunas geográficas de investigação? (c) em que estágio de descobertas está o inventário das espécies de aves em Roraima? (d) quais são os macro-hábitats prioritários para investigação? (e) quais os tipos de vegetação bem investigados e quais os que podem ser classificados como prioritários para investigação? Como resultados, detectamos Oitenta e duas localidades com algum tipo de informação ornitológica. Dentre essas, a Estação Ecológica de Maracá (442 sp), seguido pelo Parque Nacional do Viruá (420 sp), Colônia do Apiaú (320 sp), Mucajaí (267 sp), e Pacaráima (212 sp), são as cinco localidades com maior grau de conhecimento ornitológico dentro do estado. Nos últimos 20 anos apenas duas localidades ornitológicas em Roraima podem ser acrescidas à lista de sítios bem estudados de acordo com o critério de pelo menos 100 espécies registradas (peles, gravações de voz e observações visuais): Parque Nacional do Viruá e a Fazenda Paraense. Cinco áreas são aqui apontadas como lacunas de amostragem da avifauna de Roraima e devem receber prioridade para novos inventários e estudos sobre a avifauna dessa região, são elas: Noroeste do estado, nas áreas junto à fronteira com a Venezuela e divisa com o Estado do Amazonas; Baixo Rio Branco, desde a cidade de Caracaraí à sua foz; Florestas de terra firme no sudeste do Estado; As savanas do nordeste junto à fronteira com a Guiana e as regiões de floresta montana e os tepuis.

Cardiorespiratory effects of gap junction blockade in the locus coeruleus in unanesthetized adult rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)