Dynamics of the transverse Ising model with next-nearest-neighbor interactions.

We study the effects of next-nearest-neighbor (NNN) interactions on the dynamics of the one-dimensional spin-1/2 transverse Ising model in the high-temperature limit. We use exact diagonalization to obtain the time-dependent transverse correlation function and the corresponding spectral density for a tagged spin. Our results for chains of 13 spins with periodic boundary conditions produce results which are valid in the infinite-size limit. In general we find that the NNN coupling produces slower dynamics accompanied by an enhancement of the central mode behavior. Even in the case of a strong transverse field, if the NNN coupling is sufficiently large, then there is a crossover from collective mode to central mode behavior. We also obtain several recurrants for the continued fraction representation of the relaxation function.

Synchronisation and stability in river metapopulation networks.

Spatial structure in landscapes impacts population stability. Two linked components of stability have large consequences for persistence: first, statistical stability as the lack of temporal fluctuations; second, synchronisation as an aspect of dynamic stability, which erodes metapopulation rescue effects. Here, we determine the influence of river network structure on the stability of riverine metapopulations. We introduce an approach that converts river networks to metapopulation networks, and analytically show how fluctuation magnitude is influenced by interaction structure. We show that river metapopulation complexity (in terms of branching prevalence) has nonlinear dampening effects on population fluctuations, and can also buffer against synchronisation. We conclude by showing that river transects generally increase synchronisation, while the spatial scale of interaction has nonlinear effects on synchronised dynamics. Our results indicate that this dual stability - conferred by fluctuation and synchronisation dampening - emerges from interaction structure in rivers, and this may strongly influence the persistence of river metapopulations.

The nested assembly of individual-resource networks.

1. Much of the current understanding of ecological systems is based on theory that does not explicitly take into account individual variation within natural populations. However, individuals may show substantial variation in resource use. This variation in turn may be translated into topological properties of networks that depict interactions among individuals and the food resources they consume (individual-resource networks). 2. Different models derived from optimal diet theory (ODT) predict highly distinct patterns of trophic interactions at the individual level that should translate into distinct network topologies. As a consequence, individual-resource networks can be useful tools in revealing the incidence of different patterns of resource use by individuals and suggesting their mechanistic basis. 3. In the present study, using data from several dietary studies, we assembled individual-resource networks of 10 vertebrate species, previously reported to show interindividual diet variation, and used a network-based approach to investigate their structure. 4. We found significant nestedness, but no modularity, in all empirical networks, indicating that (i) these populations are composed of both opportunistic and selective individuals and (ii) the diets of the latter are ordered as predictable subsets of the diets of the more opportunistic individuals. 5. Nested patterns are a common feature of species networks, and our results extend its generality to trophic interactions at the individual level. This pattern is consistent with a recently proposed ODT model, in which individuals show similar rank preferences but differ in their acceptance rate for alternative resources. Our findings therefore suggest a common mechanism underlying interindividual variation in resource use in disparate taxa.

Eggplant (Solanum melongena) infusion has a modest and transitory effect on hypercholesterolemic subjects.

Eggplant (Solanum melongena) is consumed extensively in Brazil. It has been believed that infusion of a powdered preparation of the fruit may reduce serum cholesterol. However, there are few documented reports on its effects on cholesterol metabolism and its possible hypocholesterolemic effect has not been proved by well-controlled studies. The aim of the present study was to observe the effects of S. melongena on the serum cholesterol and triglycerides of 38 hypercholesterolemic human volunteers ingesting S. melongena infusion for five weeks. Thirty-eight hypercholesterolemic subjects receiving either S. melongena infusion (N = 19) or placebo (N = 19) participated in two clinical experiments in which the effect of S. melongena infusion was studied with (N = 16) or without (N = 38) dietary orientation. Total cholesterol and its fractions, triglycerides, and apolipoproteins A and B were measured in blood at the beginning of the experiment and three and five weeks thereafter. No differences were observed compared to control. Intraindividual analysis showed that S. melongena infusion significantly reduced the blood levels of total and LDL cholesterol and of apolipoprotein B. After dietary orientation, no intra- or intergroup differences were seen for any of the parameters analyzed. The results suggest that S. melongena infusion had a modest and transitory effect, which was not different from that obtained with standard orientation for dyslipidemia patients (diet and physical activities).

Eggplant (Solanum melongena) infusion has a modest and transitory effect on hypercholesterolemic subjects

Eggplant (Solanum melongena) is consumed extensively in Brazil. It has been believed that infusion of a powdered preparation of the fruit may reduce serum cholesterol. However, there are few documented reports on its effects on cholesterol metabolism and its possible hypocholesterolemic effect has not been proved by well-controlled studies. The aim of the present study was to observe the effects of S. melongena on the serum cholesterol and triglycerides of 38 hypercholesterolemic human volunteers ingesting S. melongena infusion for five weeks. Thirty-eight hypercholesterolemic subjects receiving either S. melongena infusion (N = 19) or placebo (N = 19) participated in two clinical experiments in which the effect of S. melongena infusion was studied with (N = 16) or without (N = 38) dietary orientation. Total cholesterol and its fractions, triglycerides, and apolipoproteins A and B were measured in blood at the beginning of the experiment and three and five weeks thereafter. No differences were observed compared to control. Intraindividual analysis showed that S. melongena infusion significantly reduced the blood levels of total and LDL cholesterol and of apolipoprotein B. After dietary orientation, no intra- or intergroup differences were seen for any of the parameters analyzed. The results suggest that S. melongena infusion had a modest and transitory effect, which was not different from that obtained with standard orientation for dyslipidemia patients (diet and physi

[Prevalence and risk factors for anemia in Southern Brazil]. / Prevalência e fatores de risco para anemia no Sul do Brasil.

OBJECTIVE: To measure the prevalence and evaluate the risk factors of anemia. METHODS: Cross sectional populational based study of the urban area of Criciuma town, in the state of Santa Catarina, Southern Brazil. The study population was a probabilistic sample of 476 children aged under three years. RESULTS: The prevalence of anemia found in the sample was 60.4% for children aged 0 to 35.9 months according to the Brault-Dubuc criteria and 54% for children aged 6 to 35.9 months according to the OMS criteria. The prevalence of anemia increases with age up to 18 months-old and then decreases. It is less prevalent in families where the father has a higher education level and where there is a higher total family income. Nevertheless, even within the 25% higher income group 40% of the children are anemic. The prevalence of anemia is higher among children living in unfinished and overcrowded houses, where the toilet is not equipped with flush, and among children who have two or more older brothers. It is also higher among teenager mothers (<20 years), and 35 years old or older mothers. The prevalence of anemia is lower among women who had 5 to 9 prenatal visits during pregnancy. Low weight at birth was associated with iron deficiency. The nutritional condition was associated with anemia only according to weight/age criteria. Hospitalizations in the last 12 months were not associated with the disease. In the hierarchical multivariate analysis children age, family income, and crowded house were the only significant variables. Reproductive health history, health service visits, birth weight, breast-feeding, anthropometry, and morbidity did not characterize a risk factor of anemia in the multivariate analysis. CONCLUSIONS: The study makes it evident that social inequality is a strong determinant of anemia. The risk imposed by anemia to children in regard to their health and intellectual development requires immediate action.

[The Children's Pastoral in Criciúma, Southern Brazil: coverage and socio-demographic characteristics of participating families]. / A Pastoral da Criança em Criciúma, Santa Catarina, Brasil: cobertura e características sócio-demográficas das famílias participantes.

This study describes the main social, economic, biological, and demographic characteristics of children and families who participate or have participated in the Children's Pastoral as compared to the overall urban population of Criciúma (Southern Brazil). A population-based cross-sectional study with a probabilistic sample of 2208 children under three years of age was conducted; 16.7% of the mothers confirmed having participated in the Pastoral at any given time, of whom 4.8% were currently participating, while the rest had dropped out. Black children and those over 12 months old or with two or more older siblings participated more frequently in the Pastoral. The main family factors associated with participation were mother's age (over 25), mother not working outside the home, low per capita income, low parental schooling, living in the neighborhood for more than 4 years, and death of sibling before age five. Reasons most often given by mothers for dropping out were migration, lack of time, and interruption of the Pastoral's activities in the neighborhood. The conclusion was that the Pastoral should prioritize the poorest of the poor and adopt measures to reduce drop-out rates.

[Assessment of the performance of Pastoral de Criança, a health support group, in promoting child survival and health education in Criciúma,a city in southern Brazil]. / Desempenho da Pastoral da Criança na promoção de ações de sobrevivência infantil e na educação em saúde em Criciúma, uma cidade do sul do Brasil.

Thousands of children younger than 5 years of age still die all over the world as a result of preventable diseases. Community intervention measures emphasizing primary health and nutritional care have been identified as one of the solutions to this problem. This article describes a population-based cross-sectional study of the Pastoral da Criança, a Roman Catholic health support group in Brazil. The study assesses whether mothers and children assisted by the Pastoral present better health indicators and have a better knowledge of basic child survival actions than non-assisted mothers and children. The study was carried out in 1996 in an urban area of the municipality of Criciúma, in the state of Santa Catarina, in southern Brazil. The sample was composed of 2,208 children under 3 years of age. The adjusted analysis taking into consideration possible confounding factors showed that the presence of the Pastoral was significantly associated with maternal knowledge of appropriate feeding measures during diarrheal episodes, optimal duration of exclusive breast-feeding, implications of feeding powdered milk to infants, correct interpretation of the infant growth curve, and knowledge of the proper vaccination schedule for infants. Participation in the Pastoral was positively associated with longer total breast-feeding duration, later introduction of bottle-feeding, higher frequency of growth monitoring visits in the quarter before the study, and availability in the home of measuring spoons for oral rehydration. No significant association was found between participation in the Pastoral and duration of predominant or exclusive breast-feeding, or correct diarrhea management. The results showed Pastoral actions have a positive effect and also revealed areas in which greater investments are needed. It is recommended that the Pastoral, as well as other similar institutions, give priority to educating mothers on child care and to recruiting mothers early in pregnancy, when the impact of these actions is potentially greater.

[Value of transthoracic Doppler echocardiography in the diagnosis and management of massive pulmonary embolism]. / Valor da ecocardiografia Doppler transtorácica no diagnóstico e conduta em pacientes com embolia pulmonar maciça.

We report the case of a 62-year-old man with massive pulmonary embolism and severe hemodynamic impairment. Transthoracic Doppler echocardiography was fundamental in confirming the diagnosis by direct visualization of intra-atrial thrombus and signs of right chamber overload. It allowed prompt administration of thrombolytic drug and follow-up monitoring. Doppler echocardiography is a non-invasive, available technique and its early application should be considered in the evaluation of patients with suspected massive pulmonary embolism.

[Longitudinal study of the mother and child population in an urban region of southern Brazil, 1993: methodological aspects and preliminary results]. / Estudo longitudinal da população materno-infantil da região urbana do Sul do Brasil, 1993: aspectos metodológicos e resultados preliminares.

All babies born in the hospitals of the city of Pelotas, Brazil, in 1982 were studied soon after delivery and followed up prospectively during the first years of their lives. In 1993, this study was repeated with a similar methodology, with the aim of assessing eventual changes in the level of maternal and child health. All five maternity hospitals in the city were visited daily and the 5,304 babies born included in the study. They were weighed and measured, and their gestational age was assessed using the Dubowitz method. Their mothers were examined and interviewed regarding a large number of risk factors. The mortality of these children was studied through the surveillance of all hospitals, cemeteries and death registries, and all hospital admissions were also recorded. Two nested case-control studies were carried out to assess risk factors for mortality and hospital morbidity. A systematic sample of 655 children were examined at home at one and three months of age, and these infants, as well as another sample of 805 children including all low-birthweight babies were also examined at the ages of six and twelve months. Their psychomotor development was also assessed. Losses to follow-up were only 6.6% at twelve months. Relative to the 1982 indicators, perinatal mortality fell by about 30% and infant mortality by almost 50%. The median duration of breastfeeding increased from 3.1 to 4.0 months. On the other hand, there was little change in the prevalences of low birthweight or of length for age at twelve months. The article that refers this abstract describes the methodology of the study and forthcoming publications will present detailed results.

PIP: All babies born in the hospitals of the city of Pelotas, Brazil, in 1982 were studied soon after delivery and followed up prospectively during the first years of their lives. In 1993 this study was repeated with a similar methodology, with the aim of assessing eventual changes in the level of maternal and child health. All five maternity hospitals in the city were visited daily and the 5304 babies born included in the study. They were weighed and measured, and their gestational age was assessed using the Dubowitz method. Their mothers were examined and interviewed regarding a large number of risk factors. The mortality of these children was studied through the surveillance of all hospitals, cemeteries, and death registries, and all hospital admissions were also recorded. Two nested case-control studies were carried out to assess risk factors for mortality and hospital morbidity. A systematic sample of 655 children was examined at home at 1 and 3 months of age, and these infants, as well as another sample of 805 children including all low-birth-weight babies, were also examined at the ages of 6 and 12 months. Their psychomotor development was also assessed. Losses to follow-up were only 6.6% at 12 months. Relative to the 1982 indicators, perinatal mortality fell by about 30% and infant mortality by almost 50%. The median duration of breast feeding increased from 3.1 to 4.0 months. On the other hand, there was little change in the prevalences of low birth weight or of length for age at 12 months. The methodology of the study is described, and forthcoming publications will present detailed results. (author's modified)