830 research outputs found

    Evaluating Brazilian mutual funds with stochastic frontiers

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    We evaluate the performance of 307 Brazilian stock mutual funds employing stochastic frontiers. We list the top ten actively managed funds and the bottom ten for the period April 2001-July 2003, and show that a fund's efficiency increases with management skill to beat the market. We also find that portfolios with low volatility tend to be more efficient. Yet we find no relationship between fund size and performance, though this might be blurred by a survivorship bias.

    Separating C-stars from Dust in the Central Region of the Seyfert 2 Galaxy NGC 1241

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    The Sy 2 galaxy NGC 1241 presents a 1.5 kpc large circumnuclear ring of star formation (CNR) embracing a small bar plus leading arms. Those structures are P alpha emitters, but barely seen in H alpha. It presents also stellar trailing arms inside the CNR. GEMINI and HST imagery allow the construction of high resolution (V-H) and (J-K_s) color maps as well as a (J-K_s) vs. K color-magnitude diagram (CMD) of this complex region. The CNR is heavily obscured in V, but a fairly transparent window appears in the direction of the nucleus. Nonetheless, the nucleus presents a (J-K_s) color that is redder than the CNR. The CNR is composed of extremely young HII regions still enshrouded in their dust cocoons. However, the nuclear (J-K_s) color can not be explained in this manner. Therefore, we propose the contribution of C-Stars as the most feasible mechanism for explaining the colors. If the nuclear stellar population is comparable to that of the LMC bar, 500 C-stars and 25000 AGB O-rich stars inside 50 pc may reproduce the observed colors. C-Stars release enriched material to the nuclear environment, probably fueling the central engine of this Sy 2 galaxy during the lifetime of stars with masses between 2 M_sun < M_C-star < 6 M_sun (C-star phase). The ejected material that remains trapped in the central potential might also explain the systematically observed increased strength of the optical CN-bands in Sy 2 galaxies and is consistent with the significant contribution of intermediate age stars to the optical continuum of low luminosity AGNs.Comment: The Astrophysical Journal Letters, accepted. 5 figure

    LANDSCAPE FRAGMENTATION AND FIRE VULNERABILITY IN PRIMARY FOREST ADJACENT TO RECENT LAND CLEARINGS IN THE AMAZON ARC OF DEFORESTATION

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    Deforestación extensiva en el Amazonas ha creado una selva bastante fragmentada en regiones con tasas altas de deforestación y de uso del fuego para limpia y mantenimiento de terrenos. El bosque en la interfase con estas deforestaciones sufre cambios drásticos en microclima, vegetación y procesos ecológicos, los cuales son favorables para la combustión bajo las copas después de una sequía prolongada. Un incremento en el uso del fuego, aunado a una mayor área de bosque vulnerable a incendios es una amenaza para la integridad y sustentabilidad de selvas tropicales. Se presentan resultados de estudios conducidos en Mato Groso de 1997 al 2003 como parte de experimentos para estudiar combustión de biomasa, tasas de liberación de carbono y flamabilidad de selvas. Se monitorearon cambios en susceptibilidad a incendios en la interfase entre el bosque y áreas recientemente deforestadas durante la temporada de sequía, al final de la cual se desarrollaron quemas experimentales. Abstract Extensive deforestation in the Amazon has created a highly fragmented forest in regions with an extensive rate of land use conversion and use of fire for land clearing, agriculture and grassland maintenance. The forest on the interface with land clearings suffers drastic changes in micro weather, vegetation, and ecological processes. Those altered conditions are favorable to sustaining understory fires after a prolonged drought. An increasing amount of fire usage, coupled with large areas of forest vulnerable to fire creates a new threat to the integrity and sustainability of the tropical forests in Amazonia and elsewhere in the tropical world. This paper presents the results of experimental burnings conducted from 1997 to 2003 in Mato Grosso. The study monitored the change in vulnerability of the interface between primary forest and recent deforested patches, monitored fire behavior and depth of fire penetration in the undisturbed forest on the edge of land clearing

    Integrated Near-Infrared Colors of Star Clusters: Analysis of the Stochastic Effects on the IMF

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    We examine the influence of stochastic effects on the integrated near-infrared light of star clusters with ages between 7.5<log(t)<9.25. To do this, we use stellar evolution models and a Monte Carlo technique to simulate the effects of stochastic variations in the numbers of main sequence, giant, and supergiant stars for single-generation stellar populations. The fluctuations in the integrated light produced by such variations are evaluated for the VJHK bands. We show that the VJHKVJHK light of the star clusters can be strongly affected by plausible stochastic fluctuations in the numbers of bright but scarce stars. In particular, the inclusion of thermally pulsing AGB stars in the stellar evolution models yields integrated colors with values in agreement with the spread seen for Large Magellanic Cloud clusters that are known to have significant number of AGB stars. Implications of this analysis are important for studies of the integrated light of stellar populations where it is not possible to resolve individual stars.Comment: 23 pages, AASTeX, 7 postscript figures, submitted to ApJ, revised versio

    Position statement of the Brazilian Academy of Rhinology on the use of antihistamines, antileukotrienes, and oral corticosteroids in the treatment of inflammatory sinonasal diseases

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    Introduction: Inflammatory conditions of the nose and paranasal sinuses are very prevalent in the general population, resulting in marked loss of quality of life in affected patients, as well as significant work, leisure, and social activity losses. These patients require specific and specialized treatment. A wide range of oral medications are available. Objective: The present document is aimed to clarify, for professionals treating patients with inflammatory sinonasal diseases, both specialists and general practitioners, specific oral therapies in noninfectious nasal inflammatory conditions. Methods: The methodology used to create this article included the search for the key words: oral corticosteroids, antihistamines, antileukotrienes, rhinitis, rhinosinusitis in the MEDLINE and EMBASE databases in the last 5 years. Since no relevant article was found for the text on the subject of interest in the last 5 years, the search was extended for another 5 years, and so on, according to the authors' needs. Results: Relevant literature was found regarding the use of antihistamines, antileukotrienes and oral corticosteroids in these conditions. The Brazilian Academy of Rhinology emphasizes, after extensive discussion by the collegiate, key points in the treatment with these drugs. Conclusion: There is support in the literature for the use of these drugshowever, final considerations about the role of each of them have been made. (C) 2017 Published by Elsevier Editora Ltda. on behalf of Associacao Brasileira de Otorrino-laringologia e Cirurgia Cervico-Facial.Univ Sao Paulo, Disciplina Otorrinolaringol, Sao Paulo, SP, BrazilUniv Sao Paulo, Fac Med, Sao Paulo, SP, BrazilUniv Sao Paulo, Fac Med, Dept Otorrinolaringol, Sao Paulo, SP, BrazilUniv Sao Paulo, Fac Med Ribeirao Preto, Dept Otorrinolaringol, Ribeirao Preto, SP, BrazilUniv Fed Sao Paulo, Ciencias Saude, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Otorrinolaringol, Sao Paulo, SP, BrazilUniv Fed Minas Gerais, Fac Med, Belo Horizonte, MG, BrazilUniv Sao Paulo, Fac Med Ribeirao Preto, Ribeirao Preto, SP, BrazilUniv Fed Bahia, Fac Med, Disciplina Otorrinolaringol, Salvador, BA, BrazilHosp Inst Paranaense Otorrinolaringol, Centro Rinite & Alergia, Curitiba, PR, BrazilUniv Estado Rio De Janeiro, Rio De Janeiro, RJ, BrazilUniv Brasilia, Fac Med, Brasilia, DF, BrazilUniv Fed Sao Paulo, Dept Otorrinolaringol & Cabeca & Pescoco, Sao Paulo, SP, BrazilUniv Luterana Brasil, Fac Med, Otorrinolaringol, Canoas, RS, BrazilMt Sinai Hosp, Dept Othorhinolaryngol, Toronto, ON, CanadaUniv Sao Paulo, Fac Med, Ciencias, Sao Paulo, SP, BrazilUniv Sao Paulo, Fac Med Ribeirao Preto, Dept Oftalmol Otorrinolaringol & Cirurgia Cabeca, Ribeirao Preto, SP, BrazilUniv Fed Sao Paulo, Ciencias Saude, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Otorrinolaringol, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Otorrinolaringol & Cabeca & Pescoco, Sao Paulo, SP, BrazilWeb of Scienc

    Guidelines for the management of neuroendocrine tumours by the Brazilian gastrointestinal tumour group

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    Neuroendocrine tumours are a heterogeneous group of diseases with a significant variety of diagnostic tests and treatment modalities. Guidelines were developed by North American and European groups to recommend their best management. However, local particularities and relativisms found worldwide led us to create Brazilian guidelines. Our consensus considered the best feasible strategies in an environment involving more limited resources. We believe that our recommendations may be extended to other countries with similar economic standards.Univ Sao Paulo, Inst Canc Estado Sao Paulo, BR-01246000 Sao Paulo, BrazilUniv Sao Paulo, Fac Med, Dept Radiol & Oncol, BR-01246903 Sao Paulo, BrazilHosp Sirio Libanes, BR-01308050 Sao Paulo, BrazilHosp Moinhos de Vento Porto Alegre, BR-90035000 Porto Alegre, RS, BrazilOncoctr, BR-30360680 Belo Horizonte, MG, BrazilUniv Fed Rio Grande do Sul, Dept Cirurgia, BR-90040060 Porto Alegre, RS, BrazilHosp Clin Porto Alegre, BR-90035903 Porto Alegre, RS, BrazilUniv Fed Ceara, Fac Med, Dept Fisiol & Farmacol, BR-60020180 Fortaleza, Ceara, BrazilHosp Univ Walter Cantidio, BR-60430370 Fortaleza, Ceara, BrazilInst Nacl Canc, BR-20230240 Rio De Janeiro, BrazilUniv Sao Paulo, Fac Med, Disciplina Endocrinol & Metabol, BR-01246903 Sao Paulo, BrazilAC Camargo Canc Ctr, Dept Surg, BR-01509010 Sao Paulo, BrazilUniv Sao Paulo, Fac Med, Dept Gastroenterol, Sao Paulo, BrazilUniv Fed Ciencias Saude Porto Alegre, BR-90050170 Porto Alegre, RS, BrazilHosp Albert Einstein, BR-05652900 Sao Paulo, BrazilHosp Base, Fac Med Sao Jose do Rio Preto, BR-15090000 Sao Paulo, BrazilSanta Casa Sao Jose do Rio Preto, BR-15025500 Sao Jose Do Rio Preto, BrazilPontificia Univ Catolica Parana, Hosp Erasto Gaertner, BR-81520060 Curitiba, Parana, BrazilUniv Fed Rio Grande do Norte, BR-59300000 Natal, RN, BrazilUniv Sao Paulo, Inst Coracao, BR-05403900 Sao Paulo, BrazilAC Camargo Canc Ctr, Med Oncol, BR-01509010 Sao Paulo, BrazilUniv Fed Sao Paulo, Disciplina Gastroenterol, BR-04021001 Sao Paulo, BrazilHosp Sao Rafael, BR-41253190 Salvador, BA, BrazilHosp Canc Barretos, Dept Cirurgia Aparelho Digest Alto & Hepatobiliop, BR-14784400 Sao Paulo, BrazilUniv Sao Paulo, Fac Med, Dept Patol, BR-01246903 Sao Paulo, BrazilClin AMO, BR-1950640 Salvador, BA, BrazilHosp Sao Jose, BR-01323001 Sao Paulo, BrazilUniv Nove de Julho, BR-02111030 Sao Paulo, BrazilUniv Fed Sao Paulo, Disciplina Gastroenterol, BR-04021001 Sao Paulo, BrazilWeb of Scienc

    Mitochondrial physiology

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    As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
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