Inclusiones fluídas e isótopos de Pb y Sr en Chipmo y Poracota, región minera de Orcopampa, Perú. Implicaciones para la exploración

Chipmo y Poracota forman parte de los depósitos epitermales miocénicos de oro y plata de los Andes centrales en el sur del Perú, entre los 3900 y 4900 metros sobre nivel del mar. Figura 1. Políticamente pertenecen a las provincias de Castilla y Condesuyos en la región de Arequipa y actualmente representan la mayor producción subterranea de oro del Perú. La producción total, a finales del 2009 fue de 2.1 Moz Au – 2.0 Moz Chipmo y 0.1 Moz Poracota–, cuentan con reservas del orden de 0.7 Moz Au y recursos estimados superan los 1.0 Moz Au. Chipmo es el deposito mas importante de la región de Orcopampa, en los últimos 15 años importantes publicaciones se han venido desarrollando: Swanson, 1998; Noble, 1999; Caddey and Sabastizagal, 1999; Mayta, 1999, Salazar et al., 2009 y Salazar 2008 y en Poracota cabe destacar a Bradford, 1999; Miranda Vidal, 2006 y Sarmiento, 2008

Testando as previsões de trade-off e pecking order sobre dividendos e dívida no Brasil

This article shows that the Brazilian companies have a low target payout ratio, although the local tax code favors dividends' distributions. The dividends paid present fast adjustment to current earnings, but part of the short-term variation in earnings is still absorbed by debt. Confirming predictions shared by the trade-off and pecking order models, more profitable firms and less levered firms have higher dividend payouts. Consistent with the pecking order model, dividends do not vary in the short-term to accommodate investments. Finally, more profitable firms and firms with fewer investments are less levered, accepting the pecking order hypothesis against the trade-off one.Este trabalho mostra que as companhias brasileiras distribuem uma proporção pequena dos lucros em dividendos apesar da legislação favorável. Os dividendos pagos são rapidamente ajustados ao lucro corrente, mas parte da variação de curto prazo nos lucros é absorvida por dívida. De acordo com a previsão comum dos modelos de trade-off e pecking order, as firmas mais lucrativas e menos endividadas distribuem uma maior proporção. Ainda de acordo com a pecking order, os dividendos não sofrem variações de curto prazo para acomodar os investimentos. Finalmente, as firmas mais lucrativas e que menos investem são as menos endividadas, favorecendo a pecking order contra trade-off

Estudio del efecto del tamaño en la estructura cristalina de nanopartículas de CoFe2O4

Se estudió como afecta el tamaño de nanopartículas de ferrita de cobalto en el desorden cristalino por efecto de superficie. Las nanopartículas se obtuvieron por el método de coprecipitación de sales. Para controlar el tamaño realizaron diferentes tratamientos térmicos posteriores a la síntesis. La estructura cristalina y la morfología se evaluaron por medio de Difracción de rayos-X y Microscopía Electrónica de Transmisión de Alta Resolución. Los resultados obtenidos demuestran en forma cuantitativa, cómo la variación en la relación superficie/volumen es responsable de las deformaciones presentes en las nanoestructuras.Fil: Menchaca Nal, Sandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologia En Polimeros y Nanotecnologia; ArgentinaFil: Londoño Calderon, Cesar Leandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologia En Polimeros y Nanotecnologia; ArgentinaFil: Pardo Saavedra, D. C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Pampillo, L. G.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Socolovsky, Leandro Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería; ArgentinaFil: Martinez Garcia, Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologia En Polimeros y Nanotecnologia; Argentin

Incidence and duration of breast-feeding by pattern of delivery: a longitudinal study in Southeastern Brazil

OBJETIVO: Comparar a incidência de amamentação conforme o tipo de parto. MATERIAL E MÉTODO: Estudo de coorte prospectivo de base populacional com 655 crianças brasileiras nascidas no ano de 1993 e acompanhadas durante o primeiro trimestre de vida, através de duas visitas domiciliares. RESULTADOS: A duração da amamentação foi similar entre os nascidos por parto vaginal e cesariana emergencial. Os nascidos por cesariana eletiva apresentaram um risco três vezes maior de interromper a lactação no primeiro mês de vida, após controle de fatores de confusão (razão de odds=3,09; 95% IC 1,3-7,2). Este aumento de risco não persitiu até o terceiro mês de vida. CONCLUSÕES: Recomenda-se aos serviços de saúde atenção especial a lactantes submetidas a cesarianas eletivas, para que seja promovido o aleitamento desde as primeiras semanas, evitando a interrupção precoce.OBJECTIVE: To compare the incidence of breastfeeding according to type of delivery. METHODOLOGY: Population-based cohort study of 655 children born in 1993 and followed up during the first three months of life through home visits. RESULTS: Breastfeeding duration was similar among babies born either by vaginal delivery or by emergency cesarean section. Babies born by elective cesarean section, however, presented a three times higher risk of stopping brestfeeding in the first month of life, after adjusting for possible confounding factors (odds ratio=3.09; 95% CI 1.3-7.2). The increased risk did not persist into the third month of life. CONCLUSIONS: It is recommended that health services pay special attention, in the promotion of breastfeeding, to babies born by elective cesarean section, as a way to avoid early weaning

Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil

Background Breastfeeding has clear short-term benefi ts, but its long-term consequences on human capital are yet to be established. We aimed to assess whether breastfeeding duration was associated with intelligence quotient (IQ), years of schooling, and income at the age of 30 years, in a setting where no strong social patterning of breastfeeding exists. Methods A prospective, population-based birth cohort study of neonates was launched in 1982 in Pelotas, Brazil. Information about breastfeeding was recorded in early childhood. At 30 years of age, we studied the IQ (Wechsler Adult Intelligence Scale, 3rd version), educational attainment, and income of the participants. For the analyses, we used multiple linear regression with adjustment for ten confounding variables and the G-formula. Findings From June 4, 2012, to Feb 28, 2013, of the 5914 neonates enrolled, information about IQ and breastfeeding duration was available for 3493 participants. In the crude and adjusted analyses, the durations of total breastfeeding and predominant breastfeeding (breastfeeding as the main form of nutrition with some other foods) were positively associated with IQ, educational attainment, and income. We identifi ed dose-response associations with breastfeeding duration for IQ and educational attainment. In the confounder-adjusted analysis, participants who were breastfed for 12 months or more had higher IQ scores (diff erence of 3·76 points, 95% CI 2·20–5·33), more years of education (0·91 years, 0·42–1·40), and higher monthly incomes (341·0 Brazilian reals, 93·8–588·3) than did those who were breastfed for less than 1 month. The results of our mediation analysis suggested that IQ was responsible for 72% of the eff ect on income. Interpretation Breastfeeding is associated with improved performance in intelligence tests 30 years later, and might have an important eff ect in real life, by increasing educational attainment and income in adulthood

Forage production and quality of common vetch mixtures with barley, oat and triticale in four phenological stages

Para determinar la producción y la calidad del forraje de la mezcla de veza común con cebada, avena, y triticale en dos proporciones de semilla (65:35; 35:65) durante cuatro etapas fenológicas, se estableció un experimento en un diseño de bloques completos al azar con arreglo factorial (3x4x4) con cuatro repeticiones. En mezclas de cultivos la mayor producción de materia seca (MS) la obtuvo la asociación avena-veza con 16.6 t ha-1 y en proporción de cultivos la avena-veza (65:35) produjo 19.9 t ha-1, durante la etapa grano masoso (P<0.001). La mayor cantidad de proteína cruda la obtuvieron las mezclas avena-veza (178 g kg-1 MS) y triticale-veza (161 g kg-1 MS) durante la etapa de embuche. Los menores valores de fibra detergente neutra los presentaron el monocultivo veza y su mezcla con avena (35:65), durante la etapa grano maduro (P<0.001). Las menores cantidades de fibra detergente ácida lo obtuvieron los monocultivos avena, veza y triticale durante la etapa grano lechoso (P<0.001). El mayor porcentaje de nutrientes digestibles totales lo obtuvo el monocultivo veza y su mezcla con cebada (65:35) durante la etapa grano lechoso, respectivamente (P<0.001). El contenido de energía neta de lactación y el valor relativo de forraje fue mayor para el monocultivo veza (P<0.001). Se concluye que la producción y calidad del forraje en mezcla de veza con cereales (cebada, avena y triticale) dependen de la etapa de cosecha. En este estudio, la mezcla avena-veza logró mayor producción de materia seca y mejor contenido de proteína cruda. Además, el valor relativo del forraje fue más alto durante la etapa grano maduro.The objective was to determine forage yield and quality of vetch mixtures with barley, oat and triticale in two seeding ratios (65:35; 35:65) at four phenological stages. To this end, a randomized block design with factorial array (3x4x4) and four replications was established. The greatest dry matter yield was obtained from the oat-vetch mixture at the grain doughy stage of maturity (16.6 t ha-1; P<0.00), while the seed proportion with the highest production was from the oat-vetch (65:35) ratio with 19.9 t ha-1 during the dough grain stage. The highest amount of crude protein was obtained from the oat-vetch (178 g kg-1 MS) and triticale-vetch (161 g kg-1 MS) mixtures during booting stage. The monoculture vetch and oats-vetch (35:65) proportion, both had lower amounts of neutral detergent fiber at the mature grain stage (P<0.001). The oat, vetch and triticale monocultures showed the lowest acid detergent fiber during milky grain stage (P<0.001). The greatest percentage of TDN was observed in vetch monoculture and its mixtures with barley (65:35) during the milky grain stage, respectively (P<0.001). The monoculture vetch provided highest values for NEL and RFV (P<0.001). In conclusion, the forage yield and quality of vetch mixtures with barley, oat and triticale depend on the maturity stage. Also, the oat-vetch mixture showed the greatest dry matter yield and high CP concentration. In addition, forage relative value was higher during the mature grain stage

Promoção da amamentação em localidade urbana da região sul do Brasil: estudo de intervenção randomizado

A randomized intervention trial to promote breast-feeding was carried out in southern Brazil. A group of 450 mothers and babies was visited at home 5, 10 and 20 days after birth and compared to a non-visited control group of the same size. Ninety-two per cent of the families visited received the three home visits planned. The evaluation of breast-feeding patterns and reasons for weaning took place 6 months after birth for both groups. Ninety-four per cent of the group visited and 92% of the non-visited controls group were traced on the occasion of the assessment. The intervention increased the duration of breastfeeding (median duration of 120 days in the group visited and 105 days in the controls; p=0.03) and delayed the introduction of milk bottles (median age of introduction of 90 days in the group visited and 60 days in the controls; p=0,01), Causes of weaning were classified as underlying, intermediate and immediate. The most common underlying cause of weaning was "the baby cried too much", which suggests that mothers should be taught about normal patterns of infant behaviour in the first weeks of life, particularly the need for crying, and the fact that this not necessarily reflects hunger.Foi realizado em Pelotas, RS, Brasil, estudo de intervenção randomizado, para a promoção do aleitamento materno. Grupo de 450 mães e lactentes foram visitados em casa aos 5, 10 e 20 dias após o nascimento, e comparados com um grupo-controle do mesmo número. Noventa e dois por cento das famílias no grupo de intervenção receberam as três visitas planejadas. A avaliação do padrão de aleitamento materno e causas de desmame aconteceu seis meses depois do nascimento para ambos os grupos. Noventa e quatro por cento do grupo de intervenção e noventa e dois por cento do grupo-controle foram encontrados na visita de avaliação. A intervenção aumentou a duração do aleitamento (mediana de 120 dias no grupo de intervenção, contra 105 dias no grupo-controle; p=0,03) e retardou a introdução do leite artificial (mediana de idade de 90 dias no grupo de intervenção e 60 dias no grupo-controle; p=0,01). As causas de desmame foram classificadas como subjacentes, intermediárias, e imediatas. A causa subjacente mais comum foi "o bebê chora muito", sugerindo que as mães devem ser instruídas a respeito dos padrões normais de comportamento do lactente nas primeiras semanas de vida, em particular da necessidade que a criança tem de chorar e o fato de que isto, não necessariamente, significa fome

Fatores de risco para mortalidade perinatal em Pelotas, RS, 1993

INTRODUCTION: Although there was a considerable reduction in infant mortality in Pelotas, Rio Grande do Sul in the last decade, its perinatal causes were reduced only by 28%. The associated factors of these causes were analised. MATERIAL AND METHOD: All hospital births and perinatal deaths were assessed by daily visits to all the maternity hospitals in the city, throughout 1993 and including the first week of 1994. RESULTS: The perinatal mortality rate was 22.1 per thousand births. The multivariate analysis showed the following risk factors: low socioeconomic level, male sex and maternal age above 35 years . Among multigravidae women, the fetal mortality rate was significantly increased for mothers with a previously low birthweight and a previous stillbirth. For early neonatal mortality the risk was significantly increased by a smaller number of antenatal visits than 5 and low birthweight. CONCLUSIONS: Main risk factors for perinatal mortality: low socioeconomic level, maternal age above 35 years and male sex. For early neonatal mortality the risk was significantly increased by a smaller number of antenatal visits than 5 and low birthweight.INTRODUÇÃO: Apesar de importante redução da mortalidade infantil em Pelotas, RS, na última década, as causas perinatais foram reduzidas em apenas 28%. Analisou-se os principais fatores associados a essas causas. MATERIAL E MÉTODO: Todos os nascimentos hospitalares e óbitos perinatais, em Pelotas, foram acompanhados através de visitas diárias aos hospitais, durante 1993 até a primeira semana de 1994. RESULTADOS: O coeficiente de mortalidade perinatal foi 22,1/1.000 nascimentos. A análise multivariada apontou os seguintes fatores de risco: baixo nível socioeconômico, sexo masculino e idade materna acima de 35 anos. Nas multíparas, encontrou-se maior risco para a mortalidade fetal naquelas que relatavam baixo peso prévio e natimorto prévio. A mortalidade neonatal precoce esteve associada com número de consultas pré-natais inferior a 5 e baixo peso ao nascer. CONCLUSÕES: Principais fatores de risco para mortalidade perinatal: baixo nível socioeconômico, idade materna elevada e sexo masculino. Para mortalidade neonatal precoce, o risco maior foi para consultas pré-natai

Effects of molecular contamination and sp2^2 carbon on oxidation of (100) single-crystal diamond surfaces

The efficacy of oxygen (O) surface terminations of specific moieties and densities on diamond depends on factors such as crystallinity, roughness, and crystal orientation. Given the wide breadth of diamond-like materials and O-termination techniques, it can be difficult to discern which method would yield the highest and most consistent O coverage on a particular subset of diamond. We first review the relevant physical parameters for O-terminating single-crystalline diamond (SCD) surfaces and summarize prior oxidation work on (100) SCD. We then report on our experimental study on X-ray Photoelectron Spectroscopy (XPS) characterization of (100) diamond surfaces treated with oxidation methods that include wet chemical oxidation, photochemical oxidation with UV illumination, and steam oxidation using atomic layer deposition. We describe a rigorous XPS peak-fitting procedure for measuring the functionalization of O-terminated samples and recommend that the reporting of peak energy positions, line shapes, and full-width-half-maximum values of the individual components, along with the residuals, are important for evaluating the quality of the peak fit. Two chemical parameters on the surface, sp$^2$ C and molecular contaminants, are also crucial towards interpreting the O coverage on the diamond surface and may account for the inconsistency in prior reported values in literature

Fatores de risco associados à hospitalização por bronquiolite aguda no período pós-neonatal

OBJECTIVE: To investigate the relationship between socioeconomic factors, maternal characteristics, breastfeeding, and hospitalization for bronchiolitis in the post-neonatal period. METHODS: A nested case-control study with a cohort of 5,304 children born in the city of Pelotas, Brazil, was conducted. The cohort study consisted of four sub-studies with their own methods and logistics. Mothers were interviewed using a standard questionnaire during in-hospital and home visits. Cases were defined as any child aged 28 to 364 days who had been hospitalized for bronchiolitis. RESULTS: Among 5,304 cohort children, 113 (2.1%) were hospitalized for bronchiolitis. The hierarchical multivariate analysis performed using logistic regression showed the following results: family income and gestational age were inversely associated with the risk of hospitalization for bronchiolitis. Breastfeeding showed to have a protective effect; children who were breastfed for less than one month had 7 times less risk for being hospitalized for acute bronchiolitis in the first three months of life. The risk for hospitalization for bronchiolitis is 57% higher in those exposed to maternal smoking than in those non-exposed. CONCLUSIONS: Hospitalization for acute bronchiolitis is inversely associated with family income, gestational age and duration of breastfeeding and positively associated with maternal smoking. There was not an association with either parity or maternal history of asthma.OBJETIVO: Investigar a relação entre fatores socioeconômicos, características maternas, aleitamento e hospitalização por bronquiolite no período pós-neonatal. MÉTODOS: Estudo caso-controle, aninhado a estudo de coorte de 5.304 crianças nascidas na cidade de Pelotas, RS. O estudo de coorte constitui-se de quatro subestudos, cada um com métodos e logística específicos. As mães foram entrevistadas por meio de questionário padronizado, em visitas hospitalares e domiciliares. Foram definidos como casos as crianças com idade entre 28 e 364 dias, que haviam sido hospitalizadas por bronquiolite. RESULTADOS: De 5.304 crianças da coorte, 113 (2,1%) foram hospitalizadas por bronquiolite. A análise multivariada hierarquizada, realizada pela regressão logística, mostrou os seguintes resultados: renda familiar, assim como idade gestacional, estiveram inversamente relacionadas ao risco de hospitalização por bronquiolite. O aleitamento materno desempenhou um fator protetor; crianças com tempo de aleitamento materno inferior a um mês tiveram risco 7 vezes maior de serem hospitalizadas por bronquiolite aguda nos primeiros três meses de vida. O risco de hospitalização por bronquiolite foi 57% maior naquelas expostas ao fumo materno. CONCLUSÕES: A hospitalização por bronquiolite está inversamente relacionada com renda familiar, idade gestacional e tempo de aleitamento materno, e diretamente relacionada com exposição a fumo materno. Não foi evidenciada associação com paridade ou história materna de asma brônquica