Residence Time Distribution Models Derived from Non-Ideal Laminar Velocity Profiles in Tubes

The theoretical E-curve for the laminar flow of non-Newtonian fluids in circular tubes may not be accurate for real tubular systems with diffusion, mechanical vibration, wall roughness, pipe fittings, curves, coils, or corrugated walls. Deviations from the idealized laminar flow reactor (LFR) cannot be well represented using the axial dispersion or the tanks-in-series models of residence time distribution (RTD). In this work, four RTD models derived from non-ideal velocity profiles in segregated tube flow are proposed. They were used to represent the RTD of three tubular systems working with Newtonian and pseudoplastic fluids. Other RTD models were considered for comparison. The proposed models provided good adjustments, and it was possible to determine the active volumes. It is expected that these models can be useful for the analysis of LFR or for the evaluation of continuous thermal processing of viscous foods.

Crystallization conditions and controls on trace element residence in the main minerals from the Pedra Branca Syenite, Brazil: An electron microprobe and LA-ICPMS study

Major and trace-element microanalyses of the main minerals from the 610 Ma Pedra Branca Syenite, southeast Brazil, allow inferences on intensive parameters of magmatic crystallization and on the partition of trace-elements among these minerals, with important implications for the petrogenetic evolution of the pluton. Two main syenite types make up the pluton, a quartz-free syenite with tabular alkali feldspar (laminated silica-saturated syenite, LSS, with Na-rich augite + phlogopite + hematite + magnetite + titanite + apatite) and a quartz-bearing syenite (laminated silica-oversaturated syenite, LSO, with scarce corroded plagioclase plus diopside + biotite +/- hornblende + ilmenite magnetite +/- titanite + apatite). Both types share a remarkable enrichment in incompatible elements as K, Ba, Sr, P and LREE. Apatite saturation temperatures of similar to 1060-1090 degrees C are the best estimates of liquidus, whereas the pressure of emplacement, based on Al-in-hornblende barometry, is estimated as 3.3 to 4.8 khan Although both units crystallized under oxidizing conditions, oxygen fugacity was probably higher in LSS, as shown by higher mg# of the mafic minerals and higher hematite contents in Hem-Ilm(ss). In contrast with the Ca-bearing alkali-feldspar from LSO, which hosts most of the whole-rock Sr and Pb, virtually Ca-free alkali-feldspar from LSS hosts similar to 50% of whole-rock Sr and similar to 80% of Pb, the remainder of these elements being shared by apatite, pyroxene and titanite. This contrast reflects a strong crystal-chemical control, whereby a higher proportion of an element with similar ratio and charge (Ca2+) enhances the residence of Sr and Pb in the M-site of alkali feldspar. The more alkaline character of the LSS magma is inferred to have inhibited zircon saturation; Zr + Hf remained in solution until late in the crystallization, and were mostly accommodated in the structure of Ca-Na pyroxene and titanite, which are one order of magnitude richer in these elements compared to the same minerals in LSO, where most of Zr and Hf are inferred to reside in zircon. The REE, Th and U reside mostly in titanite and apatite; D(REE)Tit/Ap raises steadily from 1 to 6 from La to Tb then remains constant up to Lu in the LSO sample; these values are about half as much in the LSS sample, where lower contents of incompatible elements in titanite are attributed to its greater modal abundance and earlier crystallization. (C) 2012 Elsevier B.V. All rights reserved.

Anemia prevalence and its determinants in Brazilian institutionalized elderly

Objective: To estimate the prevalence of anemia and analyze the factors associated with anemia in elderly residents of long-term care institutions. Methods: This cross-sectional study was performed in male and female elderly volunteers selected in a two-stage random sampling from long-term care institutions in the city of Maringa, Brazil (2008). A diagnosis of anemia was based on the plasma hemoglobin concentration. The independent variables analyzed were gender, age, time of residence at an institution, body mass index, and serum iron and albumin concentrations. The association between anemia and the variables was assessed using the Poisson regression with robust variance in unadjusted and adjusted analyses, considering a complex sample and a significance level of 5%. Results: The sample included 124 adults older than 60 y residing in long-term care institutions (53.0% female). The prevalence of anemia was 29% and was not significantly associated with gender, serum iron concentration, time of residence at an institution, or body mass index. Conversely, hypoalbuminemia was considered a risk factor for anemia. Conclusion: There is a high prevalence of anemia in the institutionalized elderly and hypoalbuminemia is a factor associated with this outcome. Interventions are necessary to promote improvements in the health and welfare of this population. (C) 2012 Published by Elsevier Inc.

Spatial regimes: dynamics of intentional homicides in the city of Sao Paulo between 2000 and 2008

Objective. To identify the existence of spatial and temporal patterns in the occurrence of intentional homicides in the municipality of Sao Paulo (MSP), Brazil, and to discuss the analytical value of taking such patterns into account when designing studies that address the dynamics and factors associated with the incidence of homicides. Methods. A longitudinal ecological study was conducted, having as units of analysis 13 205 census tracts and the 96 census districts that congregate these sectors in Sao Paulo. All intentional homicides reported in the city between 2000 and 2008 were analyzed. The gross homicide rates per 100 000 population was calculated as well as the global and local Bayesian estimates for each census tract during the study period. To verify the possibility of identifying different patterns of the spatial distribution of homicides, we used BoxMap and Moran's I index. Results. The homicide trends in the city of Sao Paulo in the last decade were not homogeneous and systematic. Instead, seven patterns of spatial distribution were identified; that is, seven spatial regimes for the occurrence of intentional homicides, considering the homicide rates within each census tract as well as the rates in adjacent tracts. These spatial distribution regimes were not contained within the limits of the census tracts and districts. Conclusions. The results show the importance of analyzing the spatial distribution of social phenomena without restriction of political and administrative boundaries.

Mayaro Virus Infection in Amazonia: A Multimodel Inference Approach to Risk Factor Assessment

Background: Arboviral diseases are major global public health threats. Yet, our understanding of infection risk factors is, with a few exceptions, considerably limited. A crucial shortcoming is the widespread use of analytical methods generally not suited for observational data - particularly null hypothesis-testing (NHT) and step-wise regression (SWR). Using Mayaro virus (MAYV) as a case study, here we compare information theory-based multimodel inference (MMI) with conventional analyses for arboviral infection risk factor assessment. Methodology/Principal Findings: A cross-sectional survey of anti-MAYV antibodies revealed 44% prevalence (n = 270 subjects) in a central Amazon rural settlement. NHT suggested that residents of village-like household clusters and those using closed toilet/latrines were at higher risk, while living in non-village-like areas, using bednets, and owning fowl, pigs or dogs were protective. The "minimum adequate" SWR model retained only residence area and bednet use. Using MMI, we identified relevant covariates, quantified their relative importance, and estimated effect-sizes (beta +/- SE) on which to base inference. Residence area (beta(Village) = 2.93 +/- 0.41; beta(Upland) = -0.56 +/- 0.33, beta(Riverbanks) = -2.37 +/- 0.55) and bednet use (beta = -0.95 +/- 0.28) were the most important factors, followed by crop-plot ownership (beta = 0.39 +/- 0.22) and regular use of a closed toilet/latrine (beta = 0.19 +/- 0.13); domestic animals had insignificant protective effects and were relatively unimportant. The SWR model ranked fifth among the 128 models in the final MMI set. Conclusions/Significance: Our analyses illustrate how MMI can enhance inference on infection risk factors when compared with NHT or SWR. MMI indicates that forest crop-plot workers are likely exposed to typical MAYV cycles maintained by diurnal, forest dwelling vectors; however, MAYV might also be circulating in nocturnal, domestic-peridomestic cycles in village-like areas. This suggests either a vector shift (synanthropic mosquitoes vectoring MAYV) or a habitat/habits shift (classical MAYV vectors adapting to densely populated landscapes and nocturnal biting); any such ecological/adaptive novelty could increase the likelihood of MAYV emergence in Amazonia.

Modeling of continuous thermal processing of a non-Newtonian liquid food under diffusive laminar flow in a tubular system

The classic conservative approach for thermal process design can lead to over-processing, especially for laminar flow, when a significant distribution of temperature and of residence time occurs. In order to optimize quality retention, a more comprehensive model is required. A model comprising differential equations for mass and heat transfer is proposed for the simulation of the continuous thermal processing of a non-Newtonian food in a tubular system. The model takes into account the contribution from heating and cooling sections, the heat exchange with the ambient air and effective diffusion associated with non-ideal laminar flow. The study case of soursop juice processing was used to test the model. Various simulations were performed to evaluate the effect of the model assumptions. An expressive difference in the predicted lethality was observed between the classic approach and the proposed model. The main advantage of the model is its flexibility to represent different aspects with a small computational time, making it suitable for process evaluation and design. (C) 2012 Elsevier Ltd. All rights reserved.

Income inequality and elderly self-rated health in Sao Paulo, Brazil

Purpose: To test the association between income inequality and elderly self-rated health and to propose a pathway to explain the relationship. Methods: We analyzed a sample of 2143 older individuals (60 years of age and over) from 49 distritos of the Municipality of Sao Paulo, Brazil. Bayesian multilevel logistic models were performed with poor self-rated health as the outcome variable. Results: Income inequality (measured by the Gini coefficient) was found to be associated with poor self-rated health after controlling for age, sex, income and education (odds ratio, 1.19; 95% credible interval, 1.01-1.38). When the practice of physical exercise and homicide rate were added to the model, the Gini coefficient lost its statistical significance (P>.05). We fitted a structural equation model in which income inequality affects elderly health by a pathway mediated by violence and practice of physical exercise. Conclusions: The health of older individuals may be highly susceptible to the socioeconomic environment of residence, specifically to the local distribution of income. We propose that this association may be mediated by fear of violence and lack of physical activity. (C) 2012 Elsevier Inc. All rights reserved.

Is income area level associated with blood pressure in adults regardless of individual-level characteristics? A multilevel approach

This population-based health survey was carried out in Florianopolis, Brazil, to assess the association between adult systolic blood pressure (SBP) and contextual income level, after controlling for potential individual-level confounders. A statistically significant negative association between SBP levels and contextual income was identified after adjusting for individual-level characteristics. SBP levels in the highest and in the intermediate tertiles of contextual income were 5.78 and 2.82 mmHg lower, respectively, than that observed in the bottom tertile. The findings suggest an association between income area level and blood pressure, regardless of well-known individual-level hypertension risk factors. (C) 2012 Elsevier Ltd. All rights reserved.

Soil properties in a sugarcane plantation after the application of treated sewage effluent and phosphogypsum in Brazil

In a field experiment performed in Lins County (Sao Paulo State, Brazil), treated sewage effluent (TSE) irrigation increased sugarcane yield but caused an excessive increase in the exchangeable sodium percentage (ESP) and clay dispersion after 16 months due to an intense irrigation regime (2500 mm/16 months) with sodium rich effluents. After two additional complete cycles with lower TSE irrigation rates (1200 mm year(-1)), 1700 kg ha(-1) of phosphogypsum was added to a section of the irrigated plots to evaluate its residence time and its implications on Na+ dynamics and other soil properties. Undisturbed soil cores were taken 2 years after phosphogypsum application to verify soil physical properties up to 0.2 m depth, and disturbed soil samples were taken every year up to 1 m depth for chemical analyses. After 5 years of consecutive TSE irrigation (2005-2010), soil acidity (pH approximate to 5) and basic cations (Ca approximate to 12, Mg approximate to 6 and K approximate to 2 mmol(c) kg(-1)) were maintained in adequate conditions for plant development without the necessity of liming, while acidity was increased (pH approximate to 4.5) and Ca (approximate to 9 mmol(c) kg(-1)), and the Mg (approximate to 4.5 mmol(c) kg(-1)) concentration decreased in the rainfed without phosphogypsum treatment. An increase in water retention capacity at -30 (from 0.14 to 0.17 m(3) m(-3)) and -1500 kPa (from 0.08 to 0.12 m(3) m(-3)) potentials was also observed in all TSE irrigated treatments. The plots with a phosphogypsum treatment showed average increases of 2 mmol(c) kg(-1) of Ca2+ and 7 mg kg(-1) of S-SO42- in all soil profiles and an average reduction of 2 mmol(c) kg(-1) of Na+ up to 0.4 m from 2008 to 2009. However, the extent of the chemical effects was greater after the first year compared to the second year. The high concentration of Na+ found in previous studies performed in the same area returned to low concentrations after continued TSE irrigation at lower rates, even without the phosphogypsum application. An unusual phosphorus migration was observed to the 0.4-0.8 m soil layer as a result of TSE irrigation, most likely due to a high pH and a Na carbonate-dominated TSE. (C) 2012 Elsevier B.V. All rights reserved.

Plant invasions research in Latin America: fast track to a more focused agenda

While many developed countries have invested heavily in research on plant invasions over the last 50 years, the immense region of Latin America has made little progress. Recognising this, a group of scientists working on plant invasions in Latin America met in Chile in late 2010 to develop a research agenda for the region based on lessons learned elsewhere. Our three main findings are as follows. (1) Globalisation is inevitable, but the resultant plant introductions can be slowed or prevented by effective quarantine and early intervention. Development of spatially explicit inventories, research on the invasion process and weed risk assessments can help prioritise and streamline action. (2) Eradication has limited application for plants and control is expensive and requires strict prioritisation and careful planning and evaluation. (3) Accepting the concept of novel ecosystems, new combinations of native and introduced species that no longer depend on human intervention, may help optimise invasive species management. Our vision of novel ecosystem management is through actions that: (a) maintain as much native biodiversity and ecosystem functionality as possible, (b) minimise management intervention to invasives with known impact, and (c) maximise the area of intervention. We propose the creation of a Latin American Invasive Plants Network to help focus the new research agenda for member countries. The network would coordinate research and training and establish funding priorities, develop and strengthen tools to share knowledge, and raise awareness at the community, governmental and intergovernmental levels about the social, economic and environmental costs of plant invasions.

Sero-epidemiological evaluation of changes in Plasmodium falciparum and Plasmodium vivax transmission patterns over the rainy season in Cambodia

Background: In Cambodia, malaria transmission is low and most cases occur in forested areas. Seroepidemiological techniques can be used to identify both areas of ongoing transmission and high-risk groups to be targeted by control interventions. This study utilizes repeated cross-sectional data to assess the risk of being malaria sero-positive at two consecutive time points during the rainy season and investigates who is most likely to sero-convert over the transmission season. Methods: In 2005, two cross-sectional surveys, one in the middle and the other at the end of the malaria transmission season, were carried out in two ecologically distinct regions in Cambodia. Parasitological and serological data were collected in four districts. Antibodies to Plasmodium falciparum Glutamate Rich Protein (GLURP) and Plasmodium vivax Merozoite Surface Protein-119 (MSP-119) were detected using Enzyme Linked Immunosorbent Assay (ELISA). The force of infection was estimated using a simple catalytic model fitted using maximum likelihood methods. Risks for sero-converting during the rainy season were analysed using the Classification and Regression Tree (CART) method. Results: A total of 804 individuals participating in both surveys were analysed. The overall parasite prevalence was low (4.6% and 2.0% for P. falciparum and 7.9% and 6.0% for P. vivax in August and November respectively). P. falciparum force of infection was higher in the eastern region and increased between August and November, whilst P. vivax force of infection was higher in the western region and remained similar in both surveys. In the western region, malaria transmission changed very little across the season (for both species). CART analysis for P. falciparum in the east highlighted age, ethnicity, village of residence and forest work as important predictors for malaria exposure during the rainy season. Adults were more likely to increase their antibody responses to P. falciparum during the transmission season than children, whilst members of the Charay ethnic group demonstrated the largest increases. Discussion: In areas of low transmission intensity, such as in Cambodia, the analysis of longitudinal serological data enables a sensitive evaluation of transmission dynamics. Consecutive serological surveys allow an insight into spatio-temporal patterns of malaria transmission. The use of CART enabled multiple interactions to be accounted for simultaneously and permitted risk factors for exposure to be clearly identified.

Perceived neighborhood problems: multilevel analysis to evaluate psychometric properties in a Southern adult Brazilian population

Abstract Background Physical attributes of the places in which people live, as well as their perceptions of them, may be important health determinants. The perception of place in which people dwell may impact on individual health and may be a more telling indicator for individual health than objective neighborhood characteristics. This paper aims to evaluate psychometric and ecometric properties of a scale on the perceptions of neighborhood problems in adults from Florianopolis, Southern Brazil. Methods Individual, census tract level (per capita monthly familiar income) and neighborhood problems perception (physical and social disorders) variables were investigated. Multilevel models (items nested within persons, persons nested within neighborhoods) were run to assess ecometric properties of variables assessing neighborhood problems. Results The response rate was 85.3%, (1,720 adults). Participants were distributed in 63 census tracts. Two scales were identified using 16 items: Physical Problems and Social Disorder. The ecometric properties of the scales satisfactory: 0.24 to 0.28 for the intra-class correlation and 0.94 to 0.96 for reliability. Higher values on the scales of problems in the physical and social domains were associated with younger age, more length of time residing in the same neighborhood and lower census tract income level. Conclusions The findings support the usefulness of these scales to measure physical and social disorder problems in neighborhoods.