bluuebunny/crossref_metadata_2025 huggingface dataset:
Ética na pesquisa em ciências humanas: novos desafios
Authors: Diniz Debora
Published: February 2008

O objetivo deste artigo é discutir como princípios já consolidados da ética em pesquisa podem ser incorporados à prática de revisão ética de pesquisas em Ciências Humanas, em particular etnografias ou pesquisas que utilizem as técnicas de observação participantes e entrevista aberta. Para a discussão, o fio condutor será a análise dos procedimentos metodológicos e éticos utilizados na produção do documentário etnográfico "Uma História Severina". A análise do filme sugere como ampliar os horizontes do debate sobre ética em pesquisa para além dos fundamentos biomédicos do campo é uma tarefa urgente.
Reviewing the environmental and human health knowledge base of carbon nanotubes
Authors: Helland Aasgeir , Wick Peter , Koehler Andreas , Schmid Kaspar , Som Claudia
Published: February 2008

Carbon nanotubes (CNTs) are one of the most promising materials in nanotechnology. The various synthesis, purification and postprocessing methods produce CNTs with diverse physical characteristics, appliable in many fields. Their extensive projected use makes it important to understand their potential harmful effects. Besides showing a notable range of results of some toxicology studies, this review concluded that: a) there are different types of CNTs; thus, they cannot be considered a uniform group of substances; and b) in environmental compartments, CNTs can be bioavailable to organisms. Their properties suggest a possible accumulation along the food chain and high persistence. In organisms, CNT absorption, distribution, metabolism, excretion and toxicity depend on the inherent physical and chemical characteristics (e.g., functionalization, coating, length and agglomeration state), influenced by external environmental conditions during CNT production, use, and disposal. Thus, characterized exposure scenarios could be useful in toxicology studies. However, upon reaching the lungs in enough quantity, CNTs produce a toxic response (time and dose-dependent). The risks to human health and environment should be identified for a successful introduction of CNTs in future applications.
Corpos e prazeres nos circuitos de homossociabilidade masculina do Centro do Rio de Janeiro
Authors: Rios Luis Felipe
Published: February 2008

O artigo apresenta resultados de pesquisa etnográfica sobre as bases culturais que orientam a formação de eventos corporais, em especial os relacionados ao sexo-erotismo, no circuito de homossociabilidade do Centro do Rio de Janeiro. A coleta de dados envolveu a realização de observações participantes, entrevistas com enfoque biográfico e pesquisa-intervenção entre integrantes do circuito mencionado. O principal argumento apresentado neste texto é que os diferentes eventos corporais da comunidade investigada se alicerçam em uma mesma estrutura conceptual, que foca numa transgressão ao "corpo-carne", nos moldes da filosofia de São Paulo. Uma exaltação do 'tesão', o prazer erótico proibido, que só deveria ser "utilizado" para fins reprodutivos. 'Carne' que, em vez de sublimada, é exaltada; constantemente insuflada e encantada por acréscimos de mais 'tesão'.
Hipertensão em segmentos sociais pauperizados da região do Vale do Paraíba São Paulo
Authors: Martins Ignez Salas , Oliveira Denize Cristina de , Marinho Sheila Pita , Araújo Eutália Aparecida Cândico de
Published: February 2008

O objetivo deste trabalho foi verificar as relações entre fatores socioeconômicos, ambientais e biológicos com a hipertensão, segundo gênero. A população estudada foi formada por adultos residentes em dois municípios do Vale do Paraíba (SP), uma das regiões mais pobres do estado de São Paulo. Foi composta por 274 (39,8%) homens e 415 (60,2 %) mulheres. O estudo foi realizado por meio de um modelo de regressão logística hierarquizada, aplicado separadamente para homens e mulheres. Foram estimados os odds ratios ajustados (ORaj), com intervalo de confiança de 95% e a = 0,05. Para os homens, os seguintes fatores de risco estiveram associados à hipertensão: viver na zona rural (ORaj=2,00; p=0,01); etilismo (ORaj= 1,90; p=0,03) e idade acima de 40 anos (ORaj=3,10; p<0,0001). Famílias numerosas, com mais de seis pessoas exerceram efeito protetor (ORaj=0,46; p=0,02). Para mulheres, os fatores de risco associados foram: ausência de escolaridade (ORaj= 2,37; p=0,0003); sedentarismo (ORaj=1,71; p=0,04); obesidade acompanhada de baixa estatura (ORaj= 4,66; p <0,0001) e idade acima de 40 anos ( ORaj=5,29; p=0,01). A obesidade isolada não se associou à hipertensão, nos níveis pressóricos iguais ou maiores do que os correspondentes ao estágio II do padrão de referência.
Proteção, promoção e apoio ao aleitamento materno em um hospital universitário
Authors: Almeida Gabriela Gracia de , Spiri Wilza Carla , Juliani Carmen Maria Casquel Monti , Paiva Bianca Sakamoto Ribeiro
Published: February 2008

Estudo de natureza quantitativa descritiva em um Hospital Universitário do Estado de São Paulo, teve como objetivo avaliar a promoção, proteção e apoio ao aleitamento materno através da verificação do cumprimento dos "dez passos para o sucesso do aleitamento" de acordo com a iniciativa Hospital Amigo da Criança, proposta pelo Ministério da Saúde. A avaliação revela práticas facilitadoras da amamentação, no entanto, faz-se necessário algumas mudanças nas rotinas hospitalares para a efetivação dos "dez passos". Em média, 79% das respostas foram afirmativas para o cumprimento dos passos, o que está próximo aos 80% preconizado. No entanto, se analisarmos as respostas para cada passo, identificamos pontos para serem melhorados. Chamou-nos a atenção o fato de que a prática de colocar o recém-nascido junto à mãe logo após o nascimento, permitindo a amamentação na primeira meia hora, foi relatada por 100% das mães entrevistadas que tiveram parto normal e por 80% daquelas que tiveram parto cesárea. Investimentos e mudanças em direção ao cumprimento dos dez passos contribuirão para um melhor atendimento à população e para a formação de profissionais amigos da criança.
A dieta ayurvédica e a consulta de enfermagem: uma proposta de cuidado
Authors: Gasperi Patrícia De , Raduns Vera , Ghiorzi Ângela Rosa
Published: February 2008

Neste trabalho, proponho a implementação de consultas de enfermagem, com o auxílio da compreensão ayurvédica sobre alimentação e nutrição, na realidade das Unidades Básicas de Saúde, como uma forma de cuidar de pessoas portadoras de diabetes mellitus (DM) e hipertensão arterial sistêmica (HAS). Para uma melhor compreensão, trago uma breve revisão sobre a medicina e sobre a dieta ayurvédica, dando destaque à harmonização dos doshas com o intuito de manter ou alcançar uma boa qualidade de vida. Acredito que, através da dieta ayurvédica, é possível para nós, enfermeiros, contribuirmos com a saúde de nossos pacientes através de algo que todos nós precisamos, a alimentação adequada ao nosso biótipo. Outro resultado positivo que se pode vislumbrar com a prática dessa proposta filosófica e metodológica diz respeito à convivência, ao relacionamento com o outro, ou seja, a importância de conhecer as características dos doshas, pois através desse conhecimento pode-se auxiliar as pessoas em suas conquistas e perdas.
Prevalência de sintomas osteomusculares e fatores associados em trabalhadores de uma indústria metalúrgica de Canoas - RS
Authors: Picoloto Daiana , Silveira Elaine da
Published: February 2008

A saúde do trabalhador é um campo da saúde coletiva que vem criando espaços para a identificação e prevenção de doenças relacionadas ao trabalho, em especial as osteomusculares, em função da sua abrangência e magnitude. Desta forma, foi realizado um estudo objetivando conhecer os sintomas osteomusculares apresentados pelos trabalhadores de uma indústria metalúrgica do município de Canoas-RS e a associação destes com variáveis sociodemográficas e ocupacionais. Trata-se de um estudo transversal, realizado na maior indústria metalúrgica de Canoas-RS, com a utilização de dois questionários para coleta de dados, o primeiro para obtenção das variáveis demográficas, ocupacionais e hábitos de vida e o segundo para identificar a prevalência de sintomas osteomusculares (Questionário Nórdico de Sintomas Osteomusculares). Como resultado, encontrou-se que 75,2% dos trabalhadores relataram algum tipo de sintoma osteomuscular nos últimos doze meses, 53,3% nos últimos sete dias e 38,5% já tiveram afastamento devido ao problema. Observou-se, também, associação entre sintoma osteomuscular e as variáveis sexo, faixa etária, ocupação e escolaridade. Por conseguinte, constata-se que a prevalência de sintomas osteomusculares em trabalhadores é alta, necessitando de ações de prevenção e promoção à saúde nos ambientes de trabalho.
Exposição ocupacional por uso de mercúrio em odontologia: uma revisão bibliográfica
Authors: Grigoletto Jamyle Calencio , Oliveira Aline da Silva , Muñoz Susana Inés Segura , Alberguini Leny Borghesan Albertini , Takayanagui Angela Maria Magosso
Published: February 2008

Este trabalho visa apresentar dados referentes ao gerenciamento de resíduos perigosos na área da saúde, com ênfase no uso de mercúrio em odontologia. Foi elaborado com base numa revisão bibliográfica sobre o uso do mercúrio em amálgama dentário e seus potenciais riscos toxicológicos ligados à exposição, tanto de profissionais quanto de pacientes. Os estudos levantados baseiam-se também em recomendações de alguns organismos internacionais e nacionais em relação ao uso do mercúrio e seus limites de exposição ocupacional. Os dados da literatura revelam o potencial tóxico do mercúrio, tanto para o ambiente quanto para a saúde humana. Tendo em vista que o amálgama ainda é muito utilizado na odontologia, considera-se necessário uma tomada de decisão político-administrativa que vise minimizar os riscos relacionados ao uso de amálgama em procedimentos odontológicos, voltados para a segurança ocupacional, dos indivíduos e do ambiente, baseada em diretrizes e orientações técnicas sobre seu uso, descarte e disposição final.
Nitrate‐Nitrogen Concentrations in the Perched Ground Water under Seepage‐Irrigated Potato Cropping Systems
Authors: Munoz‐Arboleda F. , Mylavarapu R. , Hutchinson C. , Portier K.
Published: February 2008

Excessive nitrogen rates for potato production in northeast Florida have been declared as a potential source of nitrate pollution in the St. Johns River watershed. This 3‐yr study examined the effect of N rates (0, 168, and 280 kg ha−1) split between planting and 40 d after planting on the NO3–N concentration in the perched ground water under potato (Solanum tuberosum cv. Atlantic) in rotation with sorghum sudan grass hybrid (Sorghum vulgare × Sorghum vulgare var. sudanese, cv. SX17), cowpea (Vigna unguiculata cv. Iron Clay), and greenbean (Phaseolus vulgare cv. Espada). Soil solution from the root zone and water from the perched ground water under potato were sampled periodically using lysimeters and wells, respectively. Fertilization at planting increased the NO3–N concentration in the perched ground water, but no effect of the legumes in rotation with potatoes on nitrate leaching was detected. Fertilization of green bean increased NO3–N concentration in the perched ground water under potato planted in the following season. The NO3–N concentration in the soil solution within the potato root zone followed a similar pattern to that of the perched ground water but with higher initial values. The NO3–N concentration in the perched ground water was proportional to the rainfall magnitude after potato planting. A significant increase in NO3–N concentration in the perched ground water under cowpea planted in summer after potato was detected for the side‐dressing of 168 kg ha−1 N applied to potato 40 d after planting but not at the 56 kg ha−1 N side‐dress. Elevation in NO3–N concentration in the perched ground water under sorghum was not significant, supporting its use as an effective N catch crop.
Chemical and Isotopic Compositions of the Minjiang River, A Headwater Tributary of the Yangtze River
Authors: Li Xiao‐Dong , Masuda Harue , Liu Cong‐Qiang
Published: February 2008

We describe the anthropogenic impacts on the major dissolved elements (Cl−, NO3−–N, SO42−, and Na+) in the water from the Minjiang River (a headwater tributary of the Yangtze River) and upper Yangtze River in relation to increasing human activity. The major element chemistry and hydrogen, oxygen, and sulfur isotopic compositions were investigated. When the Minjiang River flows through the populated Sichuan Basin, the concentrations of Cl−, NO3−–N, SO42−, and Na+ gradually increase. The increasing SO42− in the highly polluted Minjiang River had high δ34S values (+6.3 to approximately +13.6‰), implicating the anthropogenic sources of sulfur from air pollutants, domestic wastewater, industrial effluents, and agricultural fertilizers. The water quality of the upper Yangtze River does not worsen after receiving the Minjiang River because the water from the lightly polluted Jinshajiang River contributes most of the total flux in the Yangtze River. However, these rivers deserve attention and further research because the Yangtze River is the most important river in China in terms of water quality.
Evaluation of Phosphorus Characterization in Broiler Ileal Digesta, Manure, and Litter Samples: 31P‐NMR vs. HPLC
Authors: Leytem A. B. , Kwanyuen P. , Plumstead P. W. , Maguire R. O. , Brake J.
Published: February 2008

Using 31‐phosphorus nuclear magnetic resonance spectroscopy (31P‐NMR) to characterize phosphorus (P) in animal manures and litter has become a popular technique in the area of nutrient management. To date, there has been no published work evaluating P quantification in manure/litter samples with 31P‐NMR compared to other accepted methods such as high performance liquid chromatography (HPLC). To evaluate the use of 31P‐NMR to quantify myo‐inositol hexakisphosphate (phytate) in ileal digesta, manure, and litter from broilers, we compared results obtained from both 31P‐NMR and a more traditional HPLC method. The quantification of phytate in all samples was very consistent between the two methods, with linear regressions having slopes ranging from 0.94 to 1.07 and r2 values of 0.84 to 0.98. We compared the concentration of total monoester P determined with 31P‐NMR with the total inositol P content determined with HPLC and found a strong linear relationship between the two measurements having slopes ranging from 0.91 to 1.08 and r2 values of 0.73 to 0.95. This suggests that 31P‐NMR is a very reliable method for quantifying P compounds in manure/litter samples.
Fluorescence Imaging Applied to Tracer Distributions in Variably Saturated Fractured Clayey Till
Authors: Rosenbom Annette E. , Ernstsen Vibeke , Flühler Hannes , Jensen Karsten H. , Refsgaard Jens Christian , Wydler Hannes
Published: February 2008

The study of mechanisms controlling preferential flow and transport in variably saturated fractured clayey till is often hindered by insufficient spatial resolution or unknown measuring volume. With the objective to study these mechanisms while circumventing the obstacles, tracer experiments with two fluorescent tracers Acid Yellow 7 (AY7) and Sulforhodamine B (SB) were performed at three different rain events for a fall and a summer season. Irrigated areas were excavated down to depths of 2.8 m and the movement of both tracers in the exposed profiles was delineated simultaneously by high spatial resolution apparent concentration maps (pixel ∼1 mm2) obtained with an imaging device. The device consists of a light source and a CCD camera, both equipped with tracer‐specific‐filters for fluorescent light. The fluorescence images were corrected for nonuniform lighting, changing surface roughness, and varying optical properties of the soil profile. The resulting two‐dimensional apparent concentration distribution profiles of the tracers showed that: (i) relative low water content in the upper 10 cm of the irrigated till in summer had a pronounced retardation effect on the AY7‐migration and no effect on the SB‐migration; (ii) the dead‐end biopores were not activated in the fall season; (iii) only 3D fracture‐plans connected to hydraulically active 1D‐biopores contributed to the leaching; (iv) the tracer migration primary followed macropores during both seasons, though AY7 also followed a topsoil piston transport in summer; (v) the highest tracer pixel apparent concentrations were often found in macropores and most pronounced in the summer season; and (vi) 3D‐dilution in fractures seems to play a dominating role in AY7‐migration in the fall season.
Effects of Elevated Atmospheric CO2 on Invasive Plants: Comparison of Purple and Yellow Nutsedge (Cyperus rotundus L. and C. esculentus L.)
Authors: Rogers H. H. , Runion G. B. , Prior S. A. , Price A. J. , Torbert H. A. , Gjerstad D. H.
Published: February 2008

The rise in atmospheric CO2 concentration coupled with its direct, often positive, effect on the growth of plants raises the question of the response of invasive plants to elevated atmospheric CO2 levels. Response of two invasive weeds [purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (Cyperus esculentus L.)] to CO2 enrichment was tested. Plants were exposed to ambient (375 μmol mol−1) or elevated CO2 (ambient + 200 μmol mol−1) for 71 d in open top chambers. Photosynthetic rate did not differ between CO2 treatments for either species. Conductance was lower in purple nutsedge and tended to be lower in yellow nutsedge. Purple nutsedge had higher instantaneous water use efficiency; a similar trend was noted for yellow nutsedge. Purple nutsedge had greater leaf area, root length and numbers of tubers and tended to have more tillers under high CO2 In yellow nutsedge, only tuber number increased under CO2 enrichment. Leaf dry weight was greater for both species when grown under elevated CO2 Only purple nutsedge made seed heads; CO2 level did not change seed head dry weight. Root dry weight increased under the high CO2 treatment for purple nutsedge only, but tuber dry weight increased for both. Total dry weight of both species increased at elevated CO2 Purple nutsedge (under elevated CO2) tended to increase allocation belowground, which led to greater root‐to‐shoot ratio (R:S); R:S of yellow nutsedge was unaffected by CO2 enrichment. Findings suggest both species, purple more than yellow nutsedge, may be more invasive in a future high‐CO2 world.
Mitigation Assessment of Vegetated Drainage Ditches for Collecting Irrigation Runoff in California
Authors: Moore M.T. , Denton D.L. , Cooper C.M. , Wrysinski J. , Miller J.L. , Reece K. , Crane D. , Robins P.
Published: February 2008

Widespread contamination of California water bodies by the organophosphate insecticides diazinon and chlorpyrifos is well documented. While their usage has decreased over the last few years, a concomitant increase in pyrethroid usage (e.g., permethrin) (replacement insecticides) has occurred. Vegetated agricultural drainage ditches (VADD) have been proposed as a potential economical and environmentally efficient management practice to mitigate the effects of pesticides in irrigation and storm runoff. Three ditches were constructed in Yolo County, California for a field trial. A U‐shaped vegetated ditch, a V‐shaped vegetated ditch, and a V‐shaped unvegetated ditch were each amended for 8 h with a mixture of diazinon, permethrin, and suspended sediment simulating an irrigation runoff event. Water, sediment, and plant samples were collected spatially and temporally and analyzed for diazinon and permethrin concentrations. Pesticide half‐lives were similar between ditches and pesticides, ranging from 2.4 to 6.4 h. Differences in half‐distances (distance required to reduce initial pesticide concentration by 50%) among pesticides and ditches were present, indicating importance of vegetation in mitigation. Cis‐permethrin half‐distances in V ditches ranged from 22 m (V‐vegetated) to 50 m (V‐unvegetated). Half‐distances for trans‐permethrin were similar, ranging from 21 m (V‐vegetated) to 55 m (V‐unvegetated). Diazinon half‐distances demonstrated the greatest differences (55 m for V‐vegetated and 158 m for V‐unvegetated). Such economical and environmentally successful management practices will offer farmers, ranchers, and landowners a viable alternative to more conventional (and sometimes expensive) practices.
The Use of Ion Exchange Membranes for Isotope Analyses on Soil Water Sulfate: Laboratory Experiments
Authors: Kwon Jang‐Soon , Mayer Bernhard , Yun Seong‐Taek , Nightingale Michael
Published: February 2008

To investigate the potential use of anion exchange membranes (plant root simulator [PRS] probes) for isotope investigations of the soil sulfur cycle, laboratory experiments were performed to examine the sulfate exchange characteristics and to determine the extent of sulfur and oxygen isotope fractionation during sulfate sorption and desorption on the probes in aqueous solutions and simulated soil solutions. The sulfate‐exchange tests in aqueous solutions under varying experimental conditions indicated that the amount of sulfate exchanged onto PRS probes increased with increasing reaction time, initial sulfate concentration, and the number of probes used (= surface area), whereas the percentage of removal of available sulfate was constant irrespective of the initial sulfate concentration. The competition of nitrate and chloride in the solution lowered the amount of exchanged sulfate. The exchange experiments in a simulated soil under water‐saturated and water‐unsaturated conditions showed that a considerable proportion of the soil sulfate was exchanged by the PRS probes after about 10 d. There was no evidence for significant sulfur and oxygen isotope fractionation between soil sulfate and sulfate recovered from the PRS probes. Therefore, we recommend the use of PRS probes as an efficient and easy way to collect soil water sulfate for determination of its isotope composition.
Effects of Ionic Strength, Temperature, and pH on Degradation of Selected Antibiotics
Authors: Loftin Keith A. , Adams Craig D. , Meyer Michael T. , Surampalli Rao
Published: February 2008

Aqueous degradation rates, which include hydrolysis and epimerization, for chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TET), lincomycin (LNC), sulfachlorpyridazine (SCP), sulfadimethoxine (SDM), sulfathiazole (STZ), trimethoprim (TRM), and tylosin A (TYL) were studied as a function of ionic strength (0.0015, 0.050, or 0.084 mg/L as Na2HPO4), temperature (7, 22, and 35°C), and pH (2, 5, 7, 9, and 11). Multiple linear regression revealed that ionic strength did not significantly affect (α = 0.05) degradation rates for all compounds, but temperature and pH affected rates for CTC, OTC, and TET significantly (α = 0.05). Degradation also was observed for TYL at pH 2 and 11. No significant degradation was observed for LNC, SCP, SDM, STZ, TRM, and TYL (pH 5, 7, and 9) under study conditions. Pseudo first‐order rate constants, half‐lives, and Arrhenius coefficients were calculated where appropriate. In general, hydrolysis rates for CTC, OTC, and TET increased as pH and temperature increased following Arrhenius relationships. Known degradation products were used to confirm that degradation had occurred, but these products were not quantified. Half‐lives ranged from less than 6 h up to 9.7 wk for the tetracyclines and for TYL (pH 2 and 11), but no degradation of LIN, the sulfonamides, or TRM was observed during the study period. These results indicate that tetracyclines and TYL at pH 2 and 11 are prone to pH‐mediated transformation and hydrolysis in some cases, but not the sulfonamides, LIN nor TRM are inclined to degrade under study conditions. This indicates that with the exception of CTC, OTC, and TET, pH‐mediated reactions such as hydrolysis and epimerization are not likely removal mechanisms in surface water, anaerobic swine lagoons, wastewater, and ground water.
Effect of Nitrogen Fertilizer Application on Growing Season Soil Carbon Dioxide Emission in a Corn–Soybean Rotation
Authors: Al‐Kaisi Mahdi M. , Kruse Marc L. , Sawyer John E.
Published: February 2008

Nitrogen application can have a significant effect on soil carbon (C) pools, plant biomass production, and microbial biomass C processing. The focus of this study was to investigate the short‐term effect of N fertilization on soil CO2emission and microbial biomass C. The study was conducted from 2001 to 2003 at four field sites in Iowa representing major soil associations and with a corn (Zea maysL.)–soybean (Glycine maxL. Merr.) rotation. The experimental design was a randomized complete block with four replications of four N rates (0, 90, 180, and 225 kg ha−1). In the corn year, season‐long cumulative soil CO2emission was greatest with the zero N application. There was no effect of N applied in the prior year on CO2emission in the soybean year, except at one of three sites, where greater applied N decreased CO2emission. Soil microbial biomass C (MBC) and net mineralization in soil collected during the corn year was not significantly increased with increase in N rate in two out of three sites. At all sites, soil CO2emission from aerobically incubated soil showed a more consistent declining trend with increase in N rate than found in the field. Nitrogen fertilization of corn reduced the soil CO2emission rate and seasonal cumulative loss in two out of three sites, and increased MBC at only one site with the highest N rate. Nitrogen application resulted in a reduction of both emission rate and season‐long cumulative emission of CO2–C from soil.
Transport and Reaction Processes Affecting the Attenuation of Landfill Gas in Cover Soils
Authors: Molins S. , Mayer K. U. , Scheutz C. , Kjeldsen P.
Published: February 2008

Methane and trace organic gases produced in landfill waste are partly oxidized in the top 40 cm of landfill cover soils under aerobic conditions. The balance between the oxidation of landfill gases and the ingress of atmospheric oxygen into the soil cover determines the attenuation of emissions of methane, chlorofluorocarbons, and hydrochlorofluorocarbons to the atmosphere. This study was conducted to investigate the effect of oxidation reactions on the overall gas transport regime and to evaluate the contributions of various gas transport processes on methane attenuation in landfill cover soils. For this purpose, a reactive transport model that includes advection and the Dusty Gas Model for simulation of multicomponent gas diffusion was used. The simulations are constrained by data from a series of counter‐gradient laboratory experiments. Diffusion typically accounts for over 99% of methane emission to the atmosphere. Oxygen supply into the soil column is driven exclusively by diffusion, whereas advection outward offsets part of the diffusive contribution. In the reaction zone, methane consumption reduces the pressure gradient, further decreasing the significance of advection near the top of the column. Simulations suggest that production of water or accumulation of exopolymeric substances due to microbially mediated methane oxidation can significantly reduce diffusive fluxes. Assuming a constant rate of methane production within a landfill, reduction of the diffusive transport properties, primarily due to exopolymeric substance production, may result in reduced methane attenuation due to limited O2–ingress.
Regulatory T-Cells Protect From Type 1 Diabetes After Induction by Coxsackievirus Infection in the Context of Transforming Growth Factor-β
Authors: Richer Martin J. , Straka Nadine , Fang Dianne , Shanina Iryna , Horwitz Marc S.
Published: February 2008

OBJECTIVE—Coxsackievirus infections have long been associated with the induction of type 1 diabetes. Infection with coxsackievirus B4 (CB4) enhances type 1 diabetes onset in NOD mice by accelerating the presentation of β-cell antigen to autoreactive T-cells. It has been reported that a progressive defect in regulatory T-cell (Treg) function is, in part, responsible for type 1 diabetes onset in NOD mice. This defect may contribute to susceptibility to viral-induced type 1 diabetes. We asked whether the immune response after CB4 infection could be manipulated to reestablish peripheral tolerance while maintaining the immune response to virus.

RESEARCH DESIGN AND METHODS—NOD mice expressing transforming growth factor-β (TGF-β) specifically in the β-cells were infected with CB4, and the functional role of Tregs in disease protection was measured. Systemic treatments with TGF-β were used to assess its therapeutic potential.

RESULTS—Here, we report that Tregs induced after CB4 infection in the presence of TGF-β prevented type 1 diabetes. The capacity to directly infect pancreatic β-cells correlated with increased numbers of pancreatic Tregs, suggesting that presentation of β-cell antigen is integral to induction of diabetogenic protective Tregs. Furthermore, the presence of these viral induced Tregs correlated with protection from type 1 diabetes without altering the antiviral response. Finally, when TGF-β was administered systemically to NOD mice after infection, the incidence of type 1 diabetes was reduced, thereby signifying a potential therapeutic role for TGF-β.

CONCLUSIONS—We demonstrate manipulations of the immune response that result in Treg-mediated protection from type 1 diabetes without concomitant loss of the capacity to control viral infection.
Persistent Hyperinsulinemic Hypoglycemia and Maturity-Onset Diabetes of the Young Due to Heterozygous HNF4A Mutations
Authors: Kapoor Ritika R. , Locke Jonathan , Colclough Kevin , Wales Jerry , Conn Jennifer J. , Hattersley Andrew T. , Ellard Sian , Hussain Khalid
Published: February 2008

OBJECTIVE—Mutations in the human HNF4A gene encoding the hepatocyte nuclear factor (HNF)-4α are known to cause maturity-onset diabetes of the young (MODY), which is characterized by autosomal-dominant inheritance and impaired glucose-stimulated insulin secretion from pancreatic β-cells. HNF-4α has a key role in regulating the multiple transcriptional factor networks in the islet. Recently, heterozygous mutations in the HNF4A gene were reported to cause transient hyperinsulinemic hypoglycemia associated with macrosomia.

RESEARCH DESIGN AND METHODS—Three infants presented with macrosomia and severe hypoglycemia with a positive family history of MODY. The hypoglycemia was confirmed to be due to hyperinsulinism, and all three patients required diazoxide therapy to maintain normoglycemia. Two of the three infants are still requiring diazoxide therapy at 8 and 18 months, whereas one of them had resolution of hyperinsulinemic hypoglycemia at 32 months of age.

RESULTS—Sequencing of the HNF4A gene identified heterozygous mutations in all three families. In family 1, a frameshift mutation L330fsdel17ins9 (c.987 1003del17ins9; p.Leu330fs) was present in the proband; a mutation affecting the conserved A nucleotide of the intron 2 branch site (c.264–21A>G) was identified in the proband of family 2; and finally a nonsense mutation, Y16X (c.48C>G, p.Tyr16X), was found in the proband of family 3.

CONCLUSIONS—Heterozygous HNF4A mutations can therefore cause both transient and persistent hyperinsulinemic hypoglycemia associated with macrosomia. We recommend that macrosomic infants with transient or persistent hyperinsulinemic hypoglycemia should be screened for HNF4A mutations if there is a family history of youth-onset diabetes.
On recrystallization texture formation in polycrystalline fcc alloys with low stacking fault energies
Authors: Sztwiertnia Krzysztof
Published: February 2008

The texture and microstructure transformations during the annealing of highly cold-rolled silver, α-brass and phosphorus copper were studied using electron microscopy and calorimetry. The results imply that recrystallization is a superposition of several local processes which proceed in two stages. In all materials analyzed, the first stage is governed by oriented nucleation, comprising the nucleation of new grains in the areas of localized strain and their further growth accompanied by the generation of recrystallization twins. The orientation distributions of nuclei and the new grains of all materials analyzed have certain features in common at the beginning of recrystallization. The second stage in phosphorus copper is governed by oriented nucleation, while in silver and in α-brass, it is dominated by oriented growth of grains, characterized by low orientation pinning.
Hardening precipitation and mechanical properties in new Mg–Mn–Y–Gd alloys
Authors: Antion Caroline , Donnadieu Patricia , Blandin Jean-Jacques , Bley Françoise , Deschamps Alexis , Tassin Catherine , Pisch Alexander
Published: February 2008

Precipitation microstructures and mechanical properties of two new Mg–Mn–Y–Gd alloys have been studied. Small Angle X-ray Scattering and Transmission Electron Microscopy carried out on homogeneous and aged states (200°C and 250°C) have revealed Guinier–Preston zones formed from the homogeneous state at ambient temperature and first stages of precipitation consisting in DO19 type monolayer precipitates. These ultrafine precipitates show further organisation leading to the orthorhombic β′ phase. Peak-hardness microstructure is characterised by a high density of connected β′ precipitates. Overaged samples show a high level of mechanical strength and creep resistance. The related microstructure consists of stable β′ phase precipitates forming connected strings giving rise to a local strain within the matrix. Comparison with previous studies confirms the strong relationship between rare earth elements choice, precipitation microstructure and mechanical resistance.
The surface tension and density of Ag–Bi–Sn alloys
Authors: Fima Przemysław , Kucharski Marian
Published: February 2008

The sessile drop method has been used to measure the density and surface tension of liquid Ag–Bi–Sn mixtures. The density of these alloys shows linear dependence on temperature for all the compositions investigated. However, the surface tension shows curvilinear dependence on temperature for all of the compositions, except for those of a low silver content. The experimental values of the surface tension of Ag–Bi–Sn alloys are compared with those computed from the model, and relatively good agreement is observed.
Study of hydrogen absorption of aluminum melt
Authors: Wu Ruizhi , Sun Baode , Shu Da , Wang Jun
Published: February 2008

Hydrogen absorption of aluminum melt during melt treatment is one of the important factors that affect the hydrogen content of aluminum melt. In this paper, the effects of several factors (melt temperature, atmosphere humidity, and rotary speed in the rotary impellor degassing process) on hydrogen absorption are investigated quantitatively. It is found that, the higher the melt temperature, the higher the atmospheric humidity, and the higher the rotary speed in the rotary impellor degassing process, the more serious the hydrogen absorption of melt will become.
Modelling of work-hardening behaviour for laser welded magnesium alloy
Authors: Cao X. , Jahazi M. , Al-Kazzaz H. , Medraj M.
Published: February 2008

To investigate the reliability of the laser welding process for the magnesium alloy ZE41A-T5, eight butt joints were welded using the same processing parameters. These joints were tensile tested in the as-welded and aged conditions and the tensile data were analyzed from work-hardening characteristics. The flow curves cannot entirely be satisfactorily described by the Kocks–Mecking model; however, the model is still applicable to the high strain zone of the flow curves where work-hardening rate decreases linearly with flow stress. The reproducibility of the initial work-hardening rate and saturation stress is statistically analyzed. The initial work-hardening rates for the base castings and welded joints vary from approximately 4000 to 7000 MPa, i. e. 1/4 to 1/3 of the base material shear modulus. The as-welded joints have slightly higher initial work-hardening rates than the base castings. Artificial aging produces lower initial work-hardening rates compared with the base material. The saturation stress ranges approximately from 260 to 320 MPa, i. e. about 2 % of the shear modulus. The saturation stress for the welded joints is lower than that for the base material. Compared with the as-weld joints, aging decreases initial work-hardening rate but slightly increases saturation stress. Both initial work-hardening rate and saturation stress become more scattered after aging.
Thermodynamic simulation of the Bayer process
Authors: Königsberger Erich
Published: February 2008

The Gibbs energy minimiser incorporated in the thermodynamic subroutine library ChemApp and a thermodynamically consistent, ten-component Bayer liquor model were applied to a simulation of the Bayer process employed worldwide for the refining of alumina from bauxite ores. As well as the liquor cycle from digestion, clarification, precipitation, evaporation and back to digestion (including flash cooling and heating steps), calcination to alumina in a circulating fluid bed furnace was simulated. The present study not only covers temperature and concentration ranges from boehmite digestion to gibbsite precipitation, it also permits exploration of boehmite precipitation as a potential energy saving modification of the process. Furthermore, the simulation is able to predict the accumulation and precipitation of undesirable impurities in various stages of the liquor circuit. It also identifies possible reductions in the overall energy consumption of the Bayer process.
Tribological behavior of short carbon fiber or hybrid with SiCp reinforced Al alloy composites
Authors: Tang Yiping , Huang Ziyang , Liu Yuwen , Liu Lei , Hu Wenbin
Published: February 2008

Aluminum alloy matrix samples reinforced with short carbon fibers or hybrid SiCp composites were prepared, and friction and wear tests were carried out on a wear test machine using a rotation ring on a stationary disk at high load. Optical microscopy, scanning electron microscopy and energy-dispersive analysis of X-rays were used to investigate the composites, worn surface, wear debris and composition changes after wear. By comparison with Al alloy, Al/SCF and Al/SCF/SiCp, the results indicate that the incorporation of SCF into Al alloys improves the wear resistance significantly, the combination of a mechanically mixed layer formed on the worn surface and hard SiCp are responsible for the good tribological properties of the hybrid Al/SCF/SiCp composites at high load. During sliding, an obvious decrease in the temperature rise with SCF addition is attributed to the good anti-friction of SCF.
Elevated temperature compressive behavior of Nb-22Ti-16Si-7Cr-3Al-3Ta-2Hf alloy with minor Ho addition
Authors: Tian Y. X. , Guo J. T. , Cheng G. M. , Sheng L. Y. , Zhou L. Z. , He L. L. , Ye H. Q.
Published: February 2008

The microstructure and elevated temperature compressive behavior of Nb-22Ti-16Si-7Cr-3Al-3Ta-2Hf alloys with and without 0.1 at.% Ho were investigated by using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and compression tests. The results show that the addition of 0.1 at.% Ho to the matrix alloy significantly increases its elevated temperature strength at a higher strain rate, while the strengthening effect becomes weak at a lower strain rate. The elevated temperature compressive deformation behavior of the Ho-doped alloy can be adequately described by the power-law equation. The mechanism of Ho addition on elevated-temperature compressive behavior of the alloy is discussed in the paper.
Astrocytes and Brain Signalling
Authors: Panatier Aude , Robitaille Richard
Published: February 2008

Astrocytes are active, receptive and complex cells that are intimately related to neurons and synapses. They are involved in the regulation of nerve cell activity and in processing neuronal information.
Fungal Cells
Authors: Mishra Nawin C
Published: February 2008

Fungal cells have been used to produce a variety of useful items such as bread, beer, cheese and antibiotics. The study of fungal cells has also facilitated advances in medicine and agriculture.
Viruses
Authors: Minor Philip D
Published: February 2008

Viruses are microbial parasites which make the infected host manufacture more virus. They do this purely by inserting information diverting the host system to their own ends, in ways which are both subtle and profound.
Semantides and Modern Bacterial Systematics
Authors: Fuerst John A
Published: February 2008

Bacterial systematics can be defined as the scientific study of the kinds and diversity of bacterial microorganisms (i.e. prokaryotes including those in both domains Bacteria and Archaea) and their relationships.
Caulimoviridae (Plant Pararetroviruses)
Authors: Hull Roger
Published: February 2008

The Caulimoviridae family comprises six genera whose members replicate by reverse transcription and whose virus particles contain double‐stranded deoxyribonucleic acid (DNA); hence they are also called pararetroviruses. It is the only plant virus taxon whose members have double‐stranded DNA genomes.
Translation Control by Proteins
Authors: Goldman Emanuel
Published: February 2008

Translation control by proteins refers to the process by which protein synthesis of specific products is regulated by external
trans
‐acting proteins, often by repression and sometimes autoregulatory on the messenger ribonucleic acid (mRNA) encoding the very protein being synthesized, and also by activation in some systems.
Messenger
RNA
in Eukaryotes
Authors: Akusjärvi Göran , Kreivi Jan‐Peter , Petersen‐Mahrt Svend
Published: February 2008

Posttranscriptional regulation of gene expression represents an important level at which eukaryotes can expand the coding capacity of their genomes. The concept that one gene makes one protein does not apply to higher eukaryotes. Thus, a eukaryotic cell can use alternative ribonucleic acid (RNA) splicing, alternative polyadenylation and RNA editing to produce hundreds or even several thousands of protein isoforms from a single gene.
Chromosome Structure
Authors: Patrick Higgins N
Published: February 2008

Genes are organized into discrete cellular structures called chromosomes that coordinate deoxyribonucleic acid (DNA) replication and distribution of replicated genetic copies between two daughter cells. As vehicles of genetic transmission, chromosomes play a central role in Darwinian evolution.
Hepatitis: Clinical Features and Treatment
Authors: Thomas Howard , Wright Mark
Published: February 2008

There are five hepatitis viruses, A–E.

Hepatitis A and E are enterically transmitted, cause an acute hepatitis, often asymptomatic, rarely fulminant and never resulting in chronic infection. The vaccine for prevention of hepatitis A infection is well established and the vaccine against hepatitis E is currently completing clinical evaluation in field trials.

Hepatitis B causes acute and chronic hepatitis, the latter resulting in cirrhosis and hepatocellular carcinoma. Infection in adult life is usually the result of sexual activity or IV drug use, results in a symptomatic self‐limiting illness and causes chronic infection in 5–10% of cases. Infection at birth or
in utero
invariably results in chronic infection. The chronic infection requires treatment with either pegylated interferon or nucleoside analogues, if there is evidence of continuing hepatitis B virus (HBV) replication (HBV DNA >10
5
genomes mL
−1
) and evidence on liver biopsy of significant liver disease.

Hepatitis D co‐infection or super‐infection is seen in some cases of HBV infection and generally results in more rapidly progressive disease.

Hepatitis C causes acute self‐limiting hepatitis in 30–40% of cases, usually after parenteral transmission as a result of inadequate sterilization of medical equipment, IV drug use or rarely after blood transfusion in countries where adequate testing of donations is not undertaken. Sexual and neonatal transmission are rare. Most cases of chronic infection develop some degree of hepatitis and fibrosis over several decades and those with cirrhosis are at risk of developing hepatocellular carcinoma. Treatment with pegylated interferon and ribavirin produces a sustained viral response with resolution of the liver disease (cure) in 50–60% of cases with 6–12 months treatment. Response rates vary from 40% in genotypes 1 and 4 to 80% in genotypes 2 and 3.
Somatic and Stem Cell Differentiationin vitro: Model Systems
Authors: Coffman Frederick D , Studzinski George P
Published: February 2008

Because conditions of culturein vitrocannot be identical to those in the living system, cell lines culturedin vitroare referred to as ‘model systems’. Not all cell types are capable of differentiationin vitro. Procedures for studying differentiation in model systems depend on the type of culture that can be employed. Techniques employed include liquid suspension cultures, monolayer cultures and complex culture systems involving semisolid matrices or liquid overlay methods. Recent developments include systems optimized for stem cell differentiation. Suchin vitroculture techniques have applications to the study of differentiation in basic research and clinical applications.
Posttranslational Processing: Peptide Hormones and Neuropeptide Transmitters
Authors: Varro Andrea
Published: February 2008

The regulatory peptides that act as hormones, paracrine messengers or neurotransmitters are generally synthesized initially as large, inactive precursors that are converted to their active forms by a variety of different posttranslational processing steps including cleavage of the peptide chain and modification to individual residues for example by sulfation, phosphorylation, glycosylation and COOH‐terminal amidation.
Tropical Forest Animal Communities
Authors: Kricher John
Published: February 2008

Equatorial forests are unique for their high plant and animal diversities. Diversity results from speciation and is historically related to patterns of biogeography that result in part from plate tectonics. Causal factors that generate high tropical diversity are warm and wet climate, equitable seasonality, large area, high plant productivity and complex biotic interactions leading to ecological specialization. Within the tropics, wet forests exhibit the highest animal diversity, likely due to greater plant productivity and less harsh seasonality. Some species of long‐distance migrant birds have evolved in the tropics and are integral components of tropical forests during their winter residencies. Fragmentation of forests has accelerated globally and threatens numerous animal species with potential extinction. Conservation efforts must recognize factors such as importance of large area, need for animal‐assisted pollination and seed dispersal, minimal hunting pressure and habitat connectivity.
Primates and the Origin of Culture
Authors: McGrew W C
Published: February 2008

Clues to the origins of culture may lie in the diversity of behaviour seen in living large‐brained creatures with complex cognition. Comparison across apes, monkeys and other species may help us to understand what is unique and universal about human culture and what is not.
Humans: Demographic History
Authors: Harpending Henry
Published: February 2008

The genome of our species preserves a record of population dynamics – changes in size and of subdivision into partially isolated demes. Genetic data have revealed that our humans arose from a small population, with as few as several thousand members, during the last interglacial period. Since then, we have spread rapidly over the earth.
Evolution: Convergent and Parallel Evolution
Authors: Stewart Caro‐Beth
Published: February 2008

Convergence and parallelism are two forms of independent evolution of similar or identical traits; they are often taken as evidence for adaptive evolution, but can also occur due to design limitations or by chance.
DNA
Methylation: Evolution
Authors: Razin Aharon , Shemer Ruth
Published: February 2008

The understanding of how a biological feature has evolved is limited to the existing knowledge concerning this feature and the ability to interpret the available data. In an account of evolution of DNA methylation, similarities and differences in the structure of DNA methyltransferases should be considered, as well as the diversity of methylation patterns and the variety of biological processes that involve DNA methylation.