bluuebunny/crossref_metadata_2025 huggingface dataset:
Caracterização de tubo e adesivo utilizados em tubulações de plástico reforçado com fibras de vidro aplicados em plataformas marítimas
Authors: Pessanha Maikon C. R. , Dias Dylmar P. , Filgueira Marcello , Paranhos Ronaldo P. R. , Farias Otávio L. de
Published: May 2008

Na indústria de exploração e produção de petróleo, principalmente no setor offshore, os plásticos reforçados por fibras de vidro (PRFV) têm apresentado grande destaque. Isso se deve à intrínseca capacidade destes de resistir à corrosão em ambientes salinos, bem como serem materiais que apresentam elevada resistência mecânica específica. O presente trabalho buscou caracterizar tubo e adesivo utilizados em plataformas marítimas. Para tanto, as técnicas utilizadas foram: espectroscopia na região do infravermelho com transformada de Fourier (FTIR), análise termogravimétrica (TGA), análise termodinâmico-mecânica (DMTA) e temperatura de amolecimento de Vicat. Amostras do tubo de PRFV e dos componentes do adesivo (denominados de A e B) foram estudadas individualmente. Além disso, foram confeccionadas misturas, em massa, nas seguintes proporções: 40%A-60%B, 50%A-50%B e 60%A-40%B. Foi possível determinar a composição e a estrutura química dos materiais, além do comportamento mecânico à degradação térmica. Foi verificado que adesivo e tubo apresentaram desempenho satisfatório à temperatura ambiente quanto à degradação e à rigidez. Por outro lado, quando submetido ao calor, principalmente os adesivos, apresentaram queda brusca de desempenho.
Croce, Gramsci e a "autonomia da política"
Authors: Bianchi Álvaro
Published: May 2008

Na reflexão que Gramsci desenvolveu nos Quaderni del carcere, o tema da autonomia da política ocupa uma importante posição. Foi com base nessa reflexão que Gramsci desenvolveu sua pesquisa a respeito de política e da possibilidade de uma ciência política. Segundo Benedetto Croce, cabia a Nicolau Maquiavel o mérito de ter afirmado pela primeira vez a autonomia da política. Para Croce, essa autonomia permitia estabelecer uma distinção radical entre ética e política e entre "filosofia da política" e "ciência empírica da política". Gramsci tomou criticamente a reflexão croceana como ponto de partida de sua leitura de Maquiavel. O reconhecimento da autonomia da política implicava que esta não poderia ser reduzida à religião ou à ética. Como campo do conhecimento e como atividade, a ciência política e a política tinham regras próprias, que as distinguiam de outras formas do conhecimento e da atividade humana. Mas tal "autonomia" não implicava, para o marxista sardo, uma separação radical entre política e moral. Por essa razão, Gramsci encontrava em Maquiavel um precursor da filosofia da práxis em sentido pleno, ou seja, o criador de uma "ciência-ação revolucionária".
Política, burocracia e redes sociais: as nomeações para o alto escalão do Banco Central do Brasil
Authors: Olivieri Cecília
Published: May 2008

O estudo das nomeações para os cargos de direção do Banco Central do Brasil, pela análise de redes sociais, permite compreender aspectos fundamentais do sistema político-administrativo brasileiro. A escolha dos dirigentes públicos afeta a governabilidade e a governança do país. A troca entre cargos e o apoio parlamentar podem garantir a estabilidade do governo, mas também podem reduzir o controle do Presidente da República sobre a burocracia e sobre a direção das políticas públicas. A análise de redes sociais permite a construção dos critérios de escolha dos dirigentes públicos, revela novos padrões de interface entre Estado e sociedade e ilumina o estudo da accountability entre dirigentes públicos e a burocracia e entre governo e sociedade.
Reconhecimento em debate: os modelos de Honneth e Fraser em sua relação com o legado Habermasiano
Authors: Mendonça Ricardo Fabrino
Published: May 2008

O presente artigo busca delinear o debate travado por Axel Honneth e Nancy Fraser acerca da noção de reconhecimento, buscando compreender, especificamente, alguns dos aspectos que atravessam o projeto habermasiano de teoria crítica. Se a proposta de Honneth (de uma teoria da justiça calcada na noção de auto-realização) e a de Fraser (baseada no princípio da paridade de participação) parecem, à primeira vista, inconciliáveis, alguns elementos comuns podem ser encontrados quando se tem em mente o pano de fundo sobre o qual trabalham. Acreditamos que a possível produção de um modelo de reconhecimento capaz de combinar proposições de Fraser e Honneth depende da explicitação de alguns pressupostos habermasianos que permanecem implícitos nas perspectivas aqui em análise. O presente artigo traça comparações e aproximações entre os três autores no que se refere, basicamente, a três aspectos: a importância das interações ordinárias, a dimensão material das lutas sociais e as relações entre direito e moral.
Comportamento à compressão de argamassas reforçadas com fibras vegetais da Amazônia
Authors: Picanço Marcelo de Souza , Ghavami Khosrow
Published: May 2008

A busca por materiais alternativos que possam substituir as fibras de amianto, compondo o fibrocimento, tem-se tornado objeto de estudos recorrentes. As fibras vegetais surgem como opção econômica, salubre e ecologicamente adequada. O objetivo desse trabalho foi estudar o comportamento da adição da fibra de curauá em compósitos cimentícios, visando a substituir o amianto. Essa fibra mineral é bastante conhecida pelos danos que provoca à saúde humana, já tendo sido banida em muitos países industrializados. Desde 1979, o Grupo de Pesquisas em Materiais não Convencionais da PUC-Rio tem desenvolvido trabalhos sobre a aplicação das fibras vegetais, disponíveis em abundância no Brasil, na fabricação de componentes para a construção civil, visando, principalmente, à produção de habitação popular. A fibra de curauá é de uso popular, na região conhecida como Baixo-Amazonas, oeste do Estado do Pará, na manufatura de cordas, cestas e tapetes, já existindo os primeiros plantios em escala comercial. Pouco conhecida nas demais regiões do país, a fibra de curauá ainda carece de estudos específicos sobre suas propriedades físicas, químicas e mecânicas, que possibilitem sua aplicação segura em compósitos para a construção civil. Nesse artigo, foi estudado o comportamento em compressão de argamassas reforçadas com fibras de curauá. Buscou-se comparar o desempenho das fibras de curauá e de seus compósitos, com as fibras e compósitos de amianto e de outras fibras vegetais, tais como sisal e juta. Para os compósitos cimentícios com reforços de juta e de sisal, foram obtidos dados através de ensaios realizados no escopo desse trabalho. Os resultados mostraram que a fibra de curauá possui características físicas e mecânicas que a habilitam à aplicação como reforço de matrizes cimentícias, principalmente quando for almejada uma maior ductilidade e uma maior capacidade de resistência após a fissuração da matriz.
Experimento para quantificar a eficiência de aspersão de líquidos: aplicação em distribuidores espinha de peixe
Authors: Moraes Marlene Silva de , Lima José Renato Baptista de , Moraes Júnior Deovaldo de , Lia Luis Renato Bastos , Pizzo Sandro Megale
Published: May 2008

O presente texto descreve um equipamento na escala-piloto e um método simples para comparar a eficiência de distribuidores de líquido. A técnica consiste basicamente em analisar a massa do líquido coletado em 21 tubos verticais de 52mm de diâmetro interno e 800 mm de comprimento dispostos em arranjo quadrático colocados abaixo do distribuidor. Uma manta acrílica que não dispersa o líquido com 50 mm de espessura foi fixada entre o distribuidor e o banco de tubos para evitar respingos. Como exemplo de aplicação foram realizados ensaios com nove distribuidores do tipo espinha de peixe de 4 tubos paralelos cada, para uma coluna com 400 mm de diâmetro. Variaram-se o número (n) de furos (95, 127 e 159 furos/m²), o diâmetro (d) dos furos (2, 3 e 4 mm) e as vazões (q) de (1,2; 1,4 e 1,6m³/h). A melhor eficiência de espalhamento pelo menor desvio-padrão foi obtida com n de 159, d de 2 e q de 1,4 indicando as limitações de regras práticas de projeto. A pressão (p), na entrada do distribuidor, para essa condição, foi de apenas 51000 Pa (0,51 kgf/cm²) e a velocidade média (v) em cada orifício foi de 6,3 m/s.
Aplicação de emulsões na flotação do minério de zinco
Authors: Silva Tiago Alvarenga Vitorino da , Carvalho Marly Ávila de , Sigueira Marcel Guimarães , Teixeira Thiago Nantes , Pereira Carlos Alberto
Published: May 2008

Várias linhas de flotação de minérios oxidados de zinco já foram estudadas e, segundo a maioria dos pesquisadores, a flotação catiônica com altas concentrações de sulfeto de sódio, usando amina primária como coletor, tem sido a opção mais adequada para concentrar esses minérios. Nesse trabalho, investigou-se a aplicação de novos sistemas de reagentes para flotar o minério de zinco com willemita, em etapas de depressão de gangas, dispersão, sulfetização e flotação do zinco. Os testes de flotação, usando emulsão de amina com óleos vegetais e diesel, mostraram que a amina emulsificada apresentou um desempenho na flotação superior à amina não emulsificada, além de permitir uma redução significativa de sulfeto de sódio. Dos óleos vegetais estudados destacaram-se a mamona e o coco-babaçu, porém os resultados de recuperação foram inferiores ao óleo diesel.
Inclusões fluidas crepitadas, fluidos hipersalinos e aquo-carbônicos em quartzo associado a rochas micáceas no Granito Xinguara - Terreno Granito-Greenstone de Rio Maria, PA
Authors: Weber Marcelo Leopoldo , Ronchi Luiz Henrique , Althoff Fernando Jacques , Leite Albano Antônio da Silva , Dall'Agnol Roberto , Fuzikawa Kazuo
Published: May 2008

As rochas micáceas encontradas no Granito Xinguara, terreno Granito-Greenstone de Rio Maria, Pará, são compostas por muscovita e clorita com níveis de quartzo intercalados, que formam uma xistosidade bem desenvolvida. Essa xistosidade é cortada por veios de quartzo. Ambas as gerações de quartzo apresentam os mesmos tipos de inclusões fluidas em halos ou trilhas secundárias de composições variadas entre aquosas, aquo-carbônicas e saturadas em torno de grandes inclusões primárias crepitadas ou em trilhas transgranulares secundárias. A grande variação de temperaturas de homogeneização, a alta salinidade, as evidências de estrangulamento e a existência das inclusões crepitadas permitem supor forte influência de alterações pós-formacionais e reequilíbrio relacionados à intrusão do granito. Essas rochas foliadas são, portanto, enclaves metassedimentares afetados por fluidos graníticos hipersalinos aquo-carbônicos.
Caracterização Mineralógica das Argilas da Península de Santa Elena, Equador
Authors: Morales Carrera Ana Mercedes , Varajão Angélica Fortes Drummond Chicarino , Gonçalves Marcos Andrade
Published: May 2008

A Península de Santa Elena, localizada a sudoeste do litoral equatoriano, é formada por rochas ígneas e sedimentares do Cretáceo até o Quaternário. As argilas pesquisadas são provenientes da alteração de cinzas vulcânicas andinas e encontram-se inseridas nos argilitos das unidades do Eoceno Médio ao Mioceno Médio (Grupo Ancón, Formações Tosagua e Progreso). Análises mineralógicas (DRX, ATG e ATD), análises texturais (distribuição granulométrica, superfície especifica e estudo morfológico por microscopia eletrônica de varredura) e análises químicas (fluorescência de raios-X e capacidade de troca catiônica) permitiram a seleção de quatro depósitos, cujo principal argilomineral é a montmorilonita com ferro, em associação com caulinita e traços de mica. As argilas desses depósitos foram caracterizadas como bentonitas cálcicas.
Resultados preliminares da artroplastia do quadril metal-metal de superfície: análise dos primeiros 40 casos com seguimento médio de 3 anos
Authors: Moraes Mauricio de , Rodrigues Rubens , Barr Robert , Ono Nelson Keiske , Fujiki Edson Noboru , Milani Carlo
Published: May 2008

Quarenta quadris (39 pacientes) foram submetidos à artroplastia total metal-metal de superficie "resurfacing" entre 2002 e 2005. Todos foram estudados e analisados clinicamente e radiograficamente. Foram utilizados critérios clínicos, no pré e pós-operatório, pela avaliação de D'Aubigné e Postel. Radiograficamente, as áreas de radiolucência ao redor do acetábulo foram classificadas de acordo com DeLee e Charnley e, no fêmur nas zonas descritas por Amstutz et al. A idade média foi de 54,40 anos. O seguimento mínimo foi de 14 meses e o máximo de 51(média de 37,36 meses). 94,44% dos resultados clínicos foram satisfatórios no pós-operatório. Ocorreram 2 casos de soltura asséptica. Não houve fratura do fêmur durante o seguimento. Os autores consideraram esta opção técnica e de implante satisfatória e, com bons resultados no seguimento médio de 3 anos.
Brazilian Portuguese version of the Iowa Gambling Task: transcultural adaptation and discriminant validity
Authors: Malloy-Diniz Leandro Fernandes , Leite Wellington Borges , Moraes Paulo Henrique Paiva de , Correa Humberto , Bechara Antoine , Fuentes Daniel
Published: May 2008

OBJECTIVE: The Iowa Gambling Task is a neuropsychological task developed in English, most widely used to assess decision-making. The aim of this work was to adapt the Iowa Gambling Task to Brazilian Portuguese, compare it with the original version and assess its validity. METHOD: We assessed 75 Brazilian adults divided into three groups: 1) 25 healthy volunteers holding the Proficiency Certificate in English tested using the English version of the Iowa Gambling Task; 2) 25 healthy volunteers who did not speak or read English tested using the Iowa Gambling Task-Portuguese; 3) 25 Attention Deficit Hyperactivity Disorder subjects tested with the Iowa Gambling Task-Portuguese. RESULTS: No difference between groups 1 and 2 was observed. Nonetheless, we found significant differences between Attention Deficit Hyperactivity Disorder subjects and the other 2 groups on blocks 3, 4, 5, and on net score. CONCLUSION: Our results are similar to those previously described in the literature concerning adults without neuropsychiatric diseases. Since those two versions were equivalent and Attention Deficit Hyperactivity Disorder subjects performed significantly worse than healthy volunteers we can conclude that the adaptation of the Iowa Gambling Task to Brazilian Portuguese is valid and can be used for research purposes in the Brazilian context.
Distribution of grasshoppers (Othoptera: Acridoidea) in the Tapacurá ecological station (São Lourenço da Mata, PE / Brazil)
Authors: Almeida AV. , Câmara CAG.
Published: May 2008

Over the last five years, collection and periodic observation in the Tapacurá Ecological Station, São Lourenço da Mata, Pernambuco, Brazil, have been carried out to produce a systematic ecological inventory of grasshopper distribution within the station based on the classifying criteria for Acridoidea, providing new data on families, subfamilies, tribes, genera and species related to the various types of vegetation and environments the station affords.
Hypoxic environments as refuge against predatory fish in the Amazonian floodplains
Authors: Anjos MB. , De Oliveira RR. , Zuanon J.
Published: May 2008

Several groups of Amazonian fishes exhibit behavioral, morphological and physiological characteristics that allow occupying hypoxic environments, despite the energetic costs of living in such harsh conditions. One of the supposed advantages of occupying hypoxic habitats would be a lower predation pressure resulting from a lower number of piscivorous fishes in those environments. We tested this hypothesis in an area of the Amazon River floodplain through gill net fishing in normoxic and hypoxic habitats. From the 103 species caught, 38 were classified as piscivores. We found no difference in the number of piscivorous species captured in hypoxic and normoxic habitats (chi2 = 0.23; p = 0.63; df = 1) but piscivorous individuals were more numerous in normoxic than in hypoxic sampling stations (chi2 = 104.4; p < 0.001; df = 1). This indicates that environments submitted to low oxygen conditions may in fact function as refuges against piscivorous fishes in the Amazonian floodplains.
Oxygen demand during mineralization of aquatic macrophytes from an oxbow lake
Authors: Bianchini Jr. I. , Cunha-Santino MB. , Peret AM.
Published: May 2008

This study presents a kinetic model of oxygen consumption during aerobic decomposition of detritus from seven species of aquatic macrophytes: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Oxycaryum cubense and Utricularia breviscapa. The aquatic macrophytes were collected from Óleo Lagoon situated in the Mogi-Guaçu river floodplain (SP, Brazil). Mineralization experiments were performed using the closed bottles method. Incubations made with lake water and macrophytes detritus (500 mL and 200 mg.L-1 (DM), respectively) were maintained during 45 to 80 days at 20 °C under aerobic conditions and darkness. Carbon content of leachates from aquatic macrophytes detritus and dissolved oxygen concentrations were analyzed. From the results we concluded that: i) the decomposition constants differ among macrophytes; these differences being dependent primarily on molecular and elemental composition of detritus and ii) in the short term, most of the oxygen demand seems to depend upon the demineralization of the dissolved carbon fraction.
Oxygen uptake during mineralization of photosynthesized carbon from phytoplankton of the Barra Bonita Reservoir: a mesocosm study
Authors: Cunha-Santino MB. , Gouvêa SP. , Bianchini Jr I. , Vieira AAH.
Published: May 2008

This study aimed to discuss and describe the oxygen consumption during aerobic mineralization of organic products (cells and excretion products) from five unialgal cultures: Cryptomonas sp., Microcystis aeruginosa, Anabaena spiroides, Thalassiosira sp. and Aulacoseira granulata. These species were isolated from Barra Bonita reservoir (22º 29’ S and 48º 34’ W) and cultivated in the laboratory. From each culture, two decomposition chambers were prepared; each chamber contained about 130 mg.L-1 of carbon from water samples of the reservoir. The chambers were aerated and incubated in the dark at 20.0 ºC. The concentration of dissolved oxygen, pH values and electrical conductivity of the solutions were determined during a period of 10 days. The results indicated increases in oxygen consumption for all the solutions studied and also for electrical conductivity. The pH values presented a decreasing tendency throughout the experiment. Oxygen consumption varied from 43 (Aulacoseira granulata chamber) to 345 mg O2 g-1 C (Anabaena spiroides chamber). Decrease in pH values was probably due to increase in CO2 concentration from microbial respiration. Increase in electrical conductivity might be due to the liberation of ions during decomposition. The results demonstrate the potentiality of the studied genera in influencing oxygen availability followed by a die-off event. It also indicates the possibility of changing of the electrical conductivity and pH values in the water column due the aerobic algae mineralization.
Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil
Authors: Bautista AIN. , Necchi-Júnior O.
Published: May 2008

Photoacclimation of photosynthesis was investigated in a tropical population of C. glomerata (São Paulo State, southeastern Brazil, 20º 48’ 24" S and 49º 22’ 24" W) by chlorophyll fluorescence parameters and chlorophyll a content. Plants were acclimated to two levels of irradiance: low (65 ± 5 µmol.m-2.s-1) and high (300 ± 10 µmol.m-2.s-1) and exposed short-term (4 days) and long-term (28 days) under a light-dark cycle of 12:12 hours. Photosynthesis-irradiance (PI) curves revealed distinct strategies of photoacclimation. In long-term exposure, plants acclimated by altering the photosynthetic units (PSU) number and keeping fixed the PSU size, revealed by increased rates of maximum photosynthesis (Pmax), lower photosynthetic efficiency (alpha) and higher values of the saturation parameter (Ik) under high irradiance. The short-term acclimation strategy consisted of changing the PSU size, with a fixed number of PSUs, as revealed by similar Pmax but higher alpha and lower Ik under low irradiance. Chlorophyll a contents followed the general pattern reported in green algae of higher concentrations under lower irradiance. Dark/light induction curves revealed consistently higher values of potential quantum yield under low irradiance. Initial and final values showed a higher recovery capacity in the short (84.4-90.6%) term exposure than in the long-term case (81.4-81.5%). ETR (electron transport rate) and NPQ (non-photochemical quenching) values were consistently higher under low irradiance. ETR showed a continuous and steady increase along the light exposure period in the short and long-term experiments, whereas NPQ values revealed a rapid increase after 15 seconds of light exposure, kept a slightly increasing trend and stabilized in most treatments. Lower photosynthetic performance (ETR) and recovery capacity of potential quantum yield were observed, particularly in long-term exposure, suggesting that this population is constrained by the typical high light environment of tropical regions.
Population traits of the burrowing toad Rhinella fernandezae (Gallardo, 1957) (Anura, Bufonidae)
Authors: Sanchez LC. , Busch M.
Published: May 2008

Size distribution, sex ratio and use of burrows of the burrowing toad Rhinella fernandezae were studied in Buenos Aires province, Argentina. Two sites separated by approximately 300 m were studied: one was a road next to a swamp, and the other a garden of a country house located further from the swamp. We identified toad burrows, and individuals were sexed, measured and given an individual mark. Burrows were examined in subsequent months after the first sampling to assess the presence of toads. We found significant differences in the size distribution between areas, being the proportion of juveniles greater at the site next to the swamp where the reproduction of the species was observed. This result may suggest that the site located near to the swamp functions as a source habitat of individuals that migrate to the other site, where recruitment would be very scarce. Sex proportion of adults did not differ from 1:1 in neither the total population nor in each site, suggesting that there was not differential mortality by sex. Some toads changed burrows throughout the study period, but there were not differences in the frequency of change between adults and juveniles.
BTCI enhances guanylin-induced natriuresis and promotes renal glomerular and tubular effects
Authors: Carvalho AF. , Santos-Neto MS. , Monteiro HSA. , Freitas SM. , Morhy L. , Nascimento NRF. , Fonteles MC.
Published: May 2008

Guanylin and uroguanylin are small cysteine-rich peptides involved in the regulation of fluid and electrolyte homeostasis through binding and activation of guanylyl cyclases signaling molecules expressed in intestine and kidney. Guanylin is less potent than uroguanylin as a natriuretic agent and is degraded in vitro by chymotrypsin due to unique structural features in the bioactive moiety of the peptide. Thus, the aim of this study was to verify whether or not guanylin is degraded by chymotrypsin-like proteases present in the kidney brush-border membranes. The isolated perfused rat kidney assay was used in this regard. Guanylin (0.2 µM) induced no changes in kidney function. However, when pretreated by the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI - 1.0 µM; guanylin - 0.2 µM) it promoted increases in urine flow (deltaUF of 0.25 ± 0.09 mL.g-1/min, P < 0.05) and Na+ excretion (% delta ENa+ of 18.20 ± 2.17, P < 0.05). BTCI (1.0 µM) also increased %ENa+ (from 22.8 ± 1.30 to 34.4 ± 3.48, P < 0.05, 90 minutes). Furthermore, BTCI (3.0 µM) induced increases in glomerular filtration rate (GFR; from 0.96 ± 0.02 to 1.28 0.02 mL.g-1/min, P < 0.05, 60 minutes). The present paper strongly suggests that chymotrypsin-like proteases play a role in renal metabolism of guanylin and describes for the first time renal effects induced by a member of the Bowman-Birk family of protease inhibitors.
The early phyllosoma stages of spiny lobster Panulirus echinatus Smith, 1869 (Decapoda: Palinuridae) reared in the laboratory
Authors: Abrunhosa FA. , Santiago AP. , Abrunhosa JP.
Published: May 2008

The early stages of the Panulirus echinatus were hatched and reared in the laboratory. Ovigerous females were captured in their habitat and carefully transported to the laboratory. Larvae were transferred in a recirculation water tank at a density of 10 larvae.L-1. The larvae were fed on Artemia and gonads of mussel Brachydonts sp. Microalgae Dunaliella viridis was added at a concentration of 150 x 10(4) cell.mL-1. Larvae and exuviae of each zoeal stage were preserved in an alcohol 70% + glycerin (1:1) solution. The phyllosomas moulted eight times; the intermoulting period of each instar averaged about 7 to 10 days. The main morphological changes of each appendage were described in detail, illustrated and compared with previous reports.
Larval ecomorphology of 13 Libellulidae (Anisoptera, Odonata) of the Middle Rio Doce Valley, Minas Gerais, Brazil
Authors: Giacomini HC. , De Marco Jr. P.
Published: May 2008

In the lakes of the Middle Rio Doce, Minas Gerais (MG), two groups of larval Libellulidae are distinguished by preferences of habitat use: one uses mainly aquatic macrophytes and the other uses the bottom substrate. The goal of this work was to verify if there is a morphological distinction between the two groups of species. Thirteen body measures were taken from the larvae and analyzed. No difference was found between the two groups of species regarding the body size, but shape differences were observed for two morphological variables. The species that use mainly macrophytes tend to have larger relative measures of the labium and smaller measures of the abdomen width. Advantages in resource obtainment and in vulnerability to predation are probably the explanations for the morphological divergence among these larval groups.
Detectando Earnings management no Brasil: estimando os accruals discricionários
Authors: Martinez Antonio Lopo
Published: May 2008

Este artigo analisa os modelos clássicos existentes na literatura acadêmica internacional para estimar os accruals discricionários, que são uma proxy empírica para detectar Earnings Manangement. Adicionalmente, evidencia que as Cias. Brasileiras "gerenciam" os seus resultados contábeis como resposta a estímulos do mercado de capitais. O primeiro passo é elucidar o significado de alguns conceitos relevantes tais como: accruals totais e accruals discricionários. Posteriormente, após uma análise crítica dos principais modelos de accruals agregados, implementar no contexto de empresas brasileiras, o modelo Kang e Silvaramakrishnan (1995), diagnosticado como o tecnicamente mais acurado para o Brasil. Para atestar a validade do modelo aplicado, investigamse circunstâncias em que o incentivo para gerenciamento de resultados é particularmente forte. Os resultados corroboram as hipóteses de gerenciamento de resultados para: a) Evitar reportar perdas; b) Sustentar o desempenho recente e c) Piorar o resultado presente em prol de resultados futuros (take a bath).
Modelo de classificação de risco de crédito de empresas
Authors: Brito Giovani Antonio Silva , Assaf Neto Alexandre
Published: May 2008

O processo de gerenciamento de risco de crédito em instituições financeiras vem passando por uma revisão ao longo dos últimos anos. Nesse contexto, diversas novas técnicas de mensuração de risco de crédito e tomadores têm sido desenvolvidas e implementadas por grandes Bancos. O objetivo desta pesquisa é desenvolver um modelo de classificação de risco para avaliar o risco de crédito de empresas no mercado brasileiro. O modelo foi construído com base em uma amostra de empresas de capital aberto classificadas como solventes ou insolventes no período entre 1994 e 2004. A técnica estatística utilizada no desenvolvimento do modelo foi a regressão logística. As variáveis independentes são índices financeiros calculados a partir das demonstrações contábeis e utilizados para representar a situação econômico-financeira das empresas. A validação do modelo foi efetuada utilizando o método Jackknife e uma Curva ROC. Os resultados do estudo indicam que o modelo de classificação de risco desenvolvido prevê eventos de default com um ano de antecedência com bom nível de acurácia. Os resultados, também, indicam que as demonstrações contábeis contêm informações que possibilitam a classificação das empresas como prováveis solventes ou prováveis insolventes.
Um estudo sobre a aderência do Balanced Scorecard às empresas abertas e fechadas
Authors: Dietschi Daniel Augusto , Nascimento Auster Moreira
Published: May 2008

Diversos estudos têm apontado que a busca das empresas abertas em atender às expectativas dos acionistas pode muitas vezes ter como conseqüência a tomada de decisões com foco no lucro imediato. Isso teria como conseqüência a perda de oportunidades de investimento em projetos mais lucrativos, com retorno a médio e longoprazo. Alguns pesquisadores entendem que esse fato pode ser sanado com o uso de instrumentos de gestão que proporcionem o equilíbrio entre aspectos financeiros e não-financeiros na empresa. Dentre esses pesquisadores, Kaplan e Norton afirmam ser essa a principal virtude do Balanced Scorecard (BSC). Considerando o problema a que esse instrumento visa a solucionar, o presente estudo buscou identificar se as suas características são mais aderentes às empresas abertas do que às fechadas. A questão foi investigada através de uma survey envolvendo a participação de executivos de 77 empresas com faturamento acima de R$10 milhões. Análises de distribuições de freqüência, testes qui-quadrado e testes Phi e Cramérs V foram realizados com o apoio da ferramenta SPSS. Os resultados indicam que as características do BSC são mais aderentes às empresas abertas do que às fechadas, sendo os aspectos financeiros predominantes nas empresas com ações negociadas na Bolsa de Valores.
Ecophysiological factors underpinning productivity of Hevea brasiliensis
Authors: Rodrigo V.H.L.
Published: May 2008

High land productivity is a must for any commercial cultivation including Hevea brasiliensis (rubber). Also, the high demand for natural rubber has placed great pressure on expanding rubber cultivation to new and non-traditional areas. Understanding the ecophysiological principles behind the measures of productivity improvements is vital for wide application of these measures and to assess their sustainability. This review discusses the ecophysiological principles and tools used, along with the measures taken, to address productivity needs in terms of: genotype selection, determination of optimum planting density, and establishment of intercropping systems. Breeding for high yields and selection of suitable genotypes for different growing conditions are a top priority throughout the research history of rubber, however, early selection tools are necessary to reduce the time required for this process. As for any crop, photosynthesis drives the productivity of the rubber crop and, therefore, factors that govern and/or parameters that indicate the efficiency of photosynthetic productivity under field conditions could be used as tools in the selection of Hevea genotypes. Particularly for the early selection of genotypes in breeding programmes, mature crop characteristics which determine crop photosynthesis and productivity, should be linked to juvenile plant characteristics. The spatial and temporal efficiency by which plants acquire growth resources determines the overall productivity of the rubber crop, hence the optimum planting density and suitable crop combinations in intercropping systems. Changes in crop microclimate influence the efficiency of resource capture and thereby can be important for determining planting density and intercrops. Research needs regarding all the above aspects are also discussed.
Physiological characteristics of cassava tolerance to prolonged drought in the tropics: implications for breeding cultivars adapted to seasonally dry and semiarid environments
Authors: El-Sharkawy Mabrouk A.
Published: May 2008

The paper summarizes research conducted at International Center for Tropical Agriculture (CIAT) on responses of cassava to extended water shortages in the field aided by modern gas-exchange and water-relation techniques as well as biochemical assays. The aim of the research was to coordinate basic and applied aspects of crop physiology into a breeding strategy with a multidisciplinary approach. Several physiological characteristics/traits and mechanisms underpinning tolerance of cassava to drought were elucidated using a large number of genotypes from the CIAT core germplasm collection grown in various locations representing ecozones where cassava is cultivated. Most notable among these characteristics are the high photosynthetic capacity of cassava leaves in favorable environments and the maintenance of reasonable rates throughout prolonged water deficits, a crucial characteristic for high and sustainable productivity. Cassava possess a tight stomatal control over leaf gas exchange that reduces water losses when plants are subjected to soil water deficits as well as to high atmospheric evaporative demands, thus protecting leaves from severe dehydration. During prolonged water deficits, cassava reduces its canopy by shedding older leaves and forming smaller new leaves leading to less light interception, another adaptive trait to drought. Though root yield is reduced (but much less than the reduction in top growth) under water stress, the crop can recover when water becomes available by rapidly forming new canopy leaves with much higher photosynthetic rates compared to unstressed crops, thus compensating for yield losses with final yields approaching those in well-watered crops. Cassava can extract slowly water from deep soils, a characteristic of paramount importance in seasonally dry and semiarid environments where deeply stored water needs to be tapped. Screening large accessions under seasonally dry and semiarid environments showed that yield is significantly correlated with upper canopy leaf photosynthetic rates, and the association was attributed mainly to nonstomatal (anatomical/biochemical) factors. Parental materials with both high yields and photosynthetic rates were identified for incorporation into breeding and selection programs for cultivars adapted to prolonged drought coupled with high temperatures and dry air, conditions that might be further aggravated by global climate changes in tropical regions.
Ecophysiology of papaya: a review
Authors: Campostrini Eliemar , Glenn David M.
Published: May 2008

Papaya (Carica papaya L.) is a principal horticultural crop of tropical and subtropical regions. Knowledge of how papaya responds to environmental factors provides a scientific basis for the development of management strategies to optimize fruit yield and quality. A better understanding of genotypic responses to specific environmental factors will contribute to efficient agricultural zoning and papaya breeding programs. The objective of this review is to present current research knowledge related to the effect of environmental factors and their interaction with the photosynthetic process and whole-plant physiology. This review demonstrates that environmental factors such as light, wind, soil chemical and physical characteristics, temperature, soil water, relative humidity, and biotic factors such as mycorrhizal fungi and genotype profoundly affect the productivity and physiology of papaya. An understanding of the environmental factors and their interaction with physiological processes is extremely important for economically sustainable production in the nursery or in the field. With improved, science-based management, growers will optimize photosynthetic carbon assimilation and increase papaya fruit productivity and quality.
Physiology of cashew plants grown under adverse conditions
Authors: Bezerra Marlos A. , Lacerda Claudivan F. de , Gomes Filho Enéas , Abreu Carlos E. B. de , Prisco José T.
Published: May 2008

The cashew (Anacardium occidentale L.) is an important crop for semi-arid agriculture and contributes to the social and economical development of several world regions, including the northeast of Brazil. In spite of its importance, very few studies aim to understand the effects of abiotic stresses on the development and yield of the cashew. This review covers the research on cashew ecophysiology, with emphasis on the effects of water and salt stress on its development, mineral nutrition and gas exchange processes. The results presented here were obtained at different plant growth stages and under different environmental conditions of soil and climate. The ecophysiological significance of this information is also discussed.
Ecophysiology of coffee growth and production
Authors: DaMatta Fábio M. , Ronchi Cláudio P. , Maestri Moacyr , Barros Raimundo S.
Published: May 2008

After oil, coffee is the most valuable traded commodity worldwide. In this review we highlighted some aspects of coffee growth and development in addition to focusing our attention on recent advances on the (eco)physiology of production in both Coffea arabica and C. canephora, which together account for 99% of the world coffee bean production. This review is organized into sections dealing with (i) climatic factors and environmental requirements, (ii) root and shoot growth, (iii) blossoming synchronisation, fruiting and cup quality, (iv) competition between vegetative and reproductive growth and branch die-back, (v) photosynthesis and crop yield, (vi) physiological components of crop yield, (vii) shading and agroforestry systems, and (viii) high-density plantings.
High free thyroxine levels are associated with QTc prolongation in males
Authors: van Noord Charlotte , van der Deure Wendy M , Sturkenboom Miriam C J M , Straus Sabine M J M , Hofman Albert , Visser Theo J , Kors Jan A , Witteman Jacqueline C M , Stricker Bruno H Ch
Published: May 2008

The literature on the effect of excess thyroid hormone on ventricular repolarization is controversial. To study whether free thyroxine (T4) and TSH are associated with QTc prolongation we conducted population-based cohort study. This study was conducted as part of the Rotterdam Study and included 365 men and 574 women aged 55 years and older with an electrocardiogram, who were randomly sampled for the assessment of thyroid status (free T4/TSH) at baseline, after exclusion of participants with hypothyroidism, use of antithyroid drugs, thyroid hormones or digoxin, left ventricular hypertrophy, and left and right bundle branch block. Endpoints were the length of the QTc interval and risk of borderline QTc prolongation. The associations were examined by means of linear and logistic regression analysis, adjusted for age and gender, diabetes mellitus, myocardial infarction, hypertension, and heart failure. Overall, there was no significant association between TSH and QTc interval (0.8 ms (95% confidence interval (CI) −3.5, 5.2) in the first quintile compared with the fifth quintile). Subjects in the fifth quintile of free T4 did not have an increased QTc interval (3.2 ms (95% CI −1.1, 7.6)); stratification on gender showed an increment of 10.9 ms (95% CI 3.4, 18.3) in the fifth quintile in men and 1.1 ms (95% CI −4.2, 6.3) in the fifth quintile of free T4 in women. When compared with subjects in the first quintile, male subjects in the fifth quintile of free T4 had a significantly increased risk of a borderline QTc interval and QTc prolongation (odds ratio 2.40 (95% CI 1.20, 4.80)). High levels of free T4 are associated with substantial QTc prolongation in men of up to 10 ms. The fact that free T4 is also associated with a significantly increased risk of borderline and prolonged QTc values with its risk of sudden cardiac death, endorses the clinical importance of our findings.
Hypoxia induces leptin gene expression and secretion in human preadipocytes: differential effects of hypoxia on adipokine expression by preadipocytes
Authors: Wang Bohan , Wood I Stuart , Trayhurn Paul
Published: May 2008

The effect of hypoxia on the expression and secretion of major adipokines by human preadipocytes has been examined. Hypoxia (1% O2) led to an increase in the HIF-1α transcription factor subunit in cultured preadipocytes, as did incubation with the hypoxia mimetic CoCl2. Leptin mRNA was essentially undetectable in preadipocytes incubated under normoxia (21% O2), but exposure to 1% O2, or CoCl2, for 4 or 24 h resulted in an induction of leptin gene expression (measured by real-time PCR). Immunoreactive leptin was not detected in the medium from normoxic preadipocytes, but was present in the medium from the hypoxic cells. Hypoxia stimulated expression of the GLUT-1 facilitative glucose transporter gene and the vascular endothelial growth factor (VEGF) gene in preadipocytes, as in adipocytes. PPARγ and aP2 mRNA levels, markers of adipocyte differentiation, were reduced by hypoxia in both cell types. In marked contrast to adipocytes, interleukin-6 (IL-6), angiopoietin-like protein 4, and plasminogen activator inhibitor-1 expression by preadipocytes was not stimulated by low O2 tension. Consistent with the gene expression results, VEGF release into the medium from preadipocytes was increased by hypoxia, but there was no change in IL-6 secretion. It is concluded that hypoxia induces human preadipocytes to synthesize and secrete leptin. Preadipocytes and adipocytes differ in their responsiveness to low O2 tension, maturation of the response to hypoxia developing on differentiation.
Response of the bivalveUnio tumidusand freshwater communities in artificial streams for hazard assessment of methyl methacrylate
Authors: Coffinet Stéphanie , Cossu-Leguille Carole , Bassères Anne , Gonnet Jean-François , Vasseur Paule
Published: May 2008

In artificial streams (pilot rivers) supplied with the river water of Gave de Pau (France), we studied the effects of methyl methacrylate (MMA) on the autochthonous bivalve Unio tumidus transferred into the streams and on natural freshwater communities colonizing the channels. Unio tumidus and freshwater communities were exposed to MMA for 15 and 30 d, respectively, at measured concentrations ranging from 0.6 to 122 mg/L. Biomarkers studied in the digestive gland and gills of U. tumidus comprised detoxication systems (namely, antioxidant enzyme activities and glutathione status) and lipid peroxidation as a marker of cytotoxicity. Biocoenotic indicators were used to evaluate effects on benthic invertebrates and diatoms. In bivalves, a decrease in antioxidant levels was found at the lowest concentrations tested (0.6 and 6 mg/L), whereas an increase in lipid peroxidation and mortality was registered at 30 mg/L after 15 d of exposure. Disturbances in freshwater communities occurred after 30 d at MMA concentrations of greater than 30 mg/L. Antioxidant responses in bivalves were recorded at the lowest MMA concentration tested, which was close to the predicted no-effect concentration (0.74 mg/L), and cytotoxicity was registered at a concentration corresponding to the 21-d no-observed-effect concentration for Daphnia magna. On the basis of the criteria studied, antioxidant biomarkers of bivalves appeared to be more sensitive than biocoenotic indicators to MMA.
Effect of pulse herbicidal exposure onScenedesmus vacuolatus: A comparison of two photosystem II inhibitors
Authors: Vallotton Nathalie , Eggen Rik Ilda Lambertus , Escher Beate Isabella , Krayenbühl Jérôme , Chèvre Nathalie
Published: May 2008

Herbicide concentrations fluctuate in rivers following crop application and can reach high levels after rain events, yet the duration of these pulses is short. In the present study, we assessed the effect of atrazine and isoproturon pulse exposure on Scenedesmus vacuolatus (Chlorophyceae; strain 211–8b, Kessler) as well as the recovery in the postexposure period. We further explored whether the time-dependent toxicity is similar for herbicides inhibiting the photosystem II (PSII). The growth rate was assessed for different exposure durations, and in addition the inhibition of the effective quantum yield of PSII was measured to monitor the response at the target site. Atrazine and isoproturon did not have similar time-dependent effects on growth rate, despite their same primary mode of action on PSII. Atrazine was less toxic than isoproturon after 10 h of exposure, but the toxicity of both herbicides was similar after 48 h of exposure. However, both compounds inhibited the PSII effective quantum yield within 1 h following exposure. Similarly, the effective quantum yield recovered completely within 4 h after removal of the toxicants, leading to rapid recovery of algal growth. The rapid onset of effects of isoproturon on the growth of the alga during exposure suggests that a single pulse to this herbicide is likely to induce greater effects than an atrazine pulse at the same concentration, even if these effects are reversible. The information gained in the present study should support the effect assessment of sequential exposures as well as the risk evaluation of fluctuating herbicidal exposure.
Effects of bisphenol a on the development, growth, and sex ratio of the houseflyMusca domestica
Authors: Izumi Nanae , Yanagibori Ryoko , Shigeno Seiichi , Sajiki Junko
Published: May 2008

The effects of bisphenol A (BPA) on the life cycle of the housefly Musca domestica were examined. The sex ratio of the imago shifted in favor of males when eggs and larvae were exposed to BPA in culture media at concentrations of 1,000 μg kg−1 for five generations and 100 μg kg−1 for seven generations. Notably, at an initial concentration of 100 μg kg−1, BPA levels in the growth medium decreased 61% at 4 h after egg inoculation, and no BPA was detected after 24 h. Pupal weight increased upon exposure to 100 μg kg−1 BPA but decreased after exposure to 1,000 μg kg−1, suggesting highly variable concentration-dependent toxicity. Both the survival ratio of eggs to the third instar larval stage and the ratio of pupae to larvae decreased, indicating that BPA affected both eggs and larvae. A delay in the timing of emergence typically was observed in insects exposed to >100 μg kg−1 BPA. Compared to the control group, juvenile hormones II and III levels were elevated significantly in larvae between days 4 and 7 in medium spiked with 100 μg kg−1 BPA. These results suggest that exposure to environmentally relevant concentrations of BPA during the early stages of the housefly life cycle can result in various disorders (pupal weight and sex ratio) that may be a consequence of endocrine disruption.