Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-control led hydrothermal synthesis

A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes. i.e. with P(3)O(10)(5) as a complexing agent and as in orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO(4):Eu(3+)), green (LaPO(4):Ce(3+), Tb(3+)) and blue (LaPO(4):Tm(3+)) phosphors The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates) (C) 2009 Elsevier B V All rights reserved

QUADRANT-SEARCHING: A NEW TECHNIQUE TO REDUCE THE SEARCH SPACE OF THE INVERSE PROBLEM OF EIT USING BEM TO THE DIRECT PROBLEM

The image reconstruction using the EIT (Electrical Impedance Tomography) technique is a nonlinear and ill-posed inverse problem which demands a powerful direct or iterative method. A typical approach for solving the problem is to minimize an error functional using an iterative method. In this case, an initial solution close enough to the global minimum is mandatory to ensure the convergence to the correct minimum in an appropriate time interval. The aim of this paper is to present a new, simple and low cost technique (quadrant-searching) to reduce the search space and consequently to obtain an initial solution of the inverse problem of EIT. This technique calculates the error functional for four different contrast distributions placing a large prospective inclusion in the four quadrants of the domain. Comparing the four values of the error functional it is possible to get conclusions about the internal electric contrast. For this purpose, initially we performed tests to assess the accuracy of the BEM (Boundary Element Method) when applied to the direct problem of the EIT and to verify the behavior of error functional surface in the search space. Finally, numerical tests have been performed to verify the new technique.

Social and psychiatric influences on urban-rural differentials in Australian suicide

The purpose of this study was to investigate urban-rural differentials in Australian suicide rates, and to examine influences that previously have remained largely speculative. Suicide rates for males (all ages and young adults) were significantly higher in rural areas compared to urban areas. Urban-rural suicide rate differences in males were rendered nonsignificant after adjustment for migrant and area socioeconomic status. Adjusting for mental disorder prevalence, in addition to migrant status, reduced the excess suicide risk in rural areas; the excess was reduced further with addition of mental health service utilization. The implications of this study are that socioeconomic circumstances in rural populations contribute to higher male suicide rates compared to urban areas, but these conditions may be partly mediated by mental disorder prevalence and mental health service utilization.

Species richness, abundance, and body size relationships from a neotropical chironomid assemblage: Looking for patterns

We investigated two of the most studied relationships in the macroecological research program (species richness vs. body size and abundance vs. body size) of a local chironomid assemblage from southeastern Brazil. Although numerous Studies have examined these relationships, few have investigated how they vary at different temporal scales. We used data from a forested stream to document and examine these patterns at monthly intervals. Both the species body size distribution and the abundance-body size relationship varied temporally. In some months the body size distribution was skewed to the right. whereas in others it approached normality. We Found both linear relationships (with different values of slopes). and a polygonal pattern in the abundance-body size relationship. This temporal variation was not related to environmental variables. Our results suggest that body size relationships are temporally instable properties of this chironomid assemblage. (C) 2007 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

The fMRI response of the LGN and V1 to cardinal red-green, blue-yellow, and achromatic visual stimuli

We compared the responsiveness of the LGN and the early retinotopic cortical areas to stimulation of the two cone-opponent systems (red - green and blue - yellow) and the achromatic system. This was done at two contrast levels to control for any effect of contrast. MR images were acquired on seven subjects with a 4T Bruker MedSpec scanner. The early visual cortical areas were localised by phase encoded retinotopic mapping with a volumetric analysis (Dumoulin et al, 2003 NeuroImage 18 576 - 587). We initially located the LGN in four subjects by using flickering stimuli in a separate scanning session, but subsequently identified it using the experimental stimuli. Experimental stimuli were sine-wave counterphasing rings (2 Hz, 0.5 cycle deg-1), cardinal for the selective activation of the L/M cone-opponent (RG), S cone-opponent (BY), and achromatic (Ach) systems. A region of interest analysis was performed. When presented at equivalent absolute contrasts (cone contrast = 5% - 6%), the BOLD response of the LGN is strongest to isoluminant red - green stimuli and weakest to blue - yellow stimuli, with the achromatic response falling in between. Area V1, on the other hand, responds best to both chromatic stimuli, with the achromatic response falling below. The key change from the LGN to V1 is a dramatic boost in the relative blue - yellow response, which occurred at both contrast levels used. This greatly enhanced cortical response to blue - yellow relative to the red - green and achromatic responses may be due to an increase in cell number and/or cell response between the LGN and V1. We speculate that the effect might reflect the operation of contrast constancy across colour mechanisms at the cortical level.

Spatial bias and temporal lag in tactile space perception

Constructing a veridical spatial map by touch poses at least two problems for a perceptual system. First, as the hand is moved through space, the locations of features may be displaced if there is an uncorrected lag between the moment the hand encounters a feature and the time that feature is encoded on a spatial map. Second, due to the sequential nature of the process, some form of memory, which itself may be subject to spatial distortions, is required for integration of spatial samples. We investigated these issues using a task involving active haptic exploration with a stylus swept back and forth in the horizontal plane at the wrist. Remembered locations of tactile targets were shifted towards the medial axis of the forearm, suggesting a central tendency in haptic spatial memory, while evidence for a displacement of perceived locations in the direction of sweep motion was consistent with processing delays.

Predictors of Lethality in Severe Leptospirosis in Urban Brazil

To ascertain prognostic factors associated with fatal outcomes in severe leptospirosis, a retrospective case-control study was done using population-based surveillance data. Centralized death certificate reporting of leptospirosis mortality was combined with details of patients` hospitalizations, which were obtained from hospitals representing all sectors of Sao Paulo city. Among identified leptospirosis cases, 89 lethal cases and 281 survivor cases were analyzed. Predictors of death included age > 40 years, development of oliguria, platelet count < 70,000/mu L, creatinine > 3 mg/dL. and pulmonary involvement. The latter was the strongest risk Factor with all estimated odds ratio of 6.0 (95% confidence interval: 3.0-12.0). Serologic findings with highest titer against Leptospira interrogans serovar Copenhageni did not show significant differences between survivors and non-survivors. Lung involvement was an important predictor of death in leptospirosis in Sao Paulo, of relevance in leptospirosis-endemic regions where this complication is common.

Dictyosphaerin: A novel bicyclic lipid from a southern Australian marine green algae, Dictyosphaeria sericea

The novel bicyclic lipid, dictyosphaerin (1), has been isolated from the southern Australian marine green alga Dictyosphaeria sericea. The molecular structure for 1 was secured by chemical derivatization and detailed spectroscopic analysis.

The time course of vasoconstriction and endothelin receptor A expression in pulmonary arterioles of mice continuously exposed to ambient urban levels of air pollution

The present study aimed to verify the time course of the effects of environmental levels of urban air pollution toxicity on lung arterioles. BALB/c mice (n = 56) were continuously exposed to selective chambers equipped with (filtered, F) or without (non-filtered, NF) filter devices for particles and toxic gases for 24 h/day, over 14, 21, 30 or 45 days. After exposure, we evaluated the lumen-wall relationship (an estimator of arteriolar narrowing), endothelial nitric oxide synthase (eNOS) and endothelin type A receptor (ETAr) expression in the vascular wall and inflammatory influx of the peribronchiolar area. Concentrations of fine particulate matter (PM <= 2.5 mu g/m(3)), nitrogen dioxide (NO(2)), black smoke (BS), humidity and temperature in both the environment and inside the chambers were measured daily. Filters cleared 100% of BS and 97% of PM inside the F chamber. The arteriole wall of the lungs of mice from NF chamber had an increased ETAr expression (p <= 0.042) concomitant to a decrease in the lumen/wall ratio (p = 0.02) on the early days of exposure, compared to controls. They also presented a progressive increment of inflammatory influx in the peribronchiolar area during the study (p = 0.04) and decrement of the eNOS expression on the 45th day of exposure in both vascular layers (p <= 0.03). We found that after 14 days of exposure, the ambient levels of air pollutants in Sao Paulo induced vasoconstriction that was associated with an increase in ETAr expression. These vascular results do not appear to be coupled to the progressive inflammatory influx in lung tissue, suggesting a down-regulation of vasoconstrictive mechanisms through an imbalance in the cytokines network. It is likely that these responses are protective measures that decrease tissue damage brought about by continuous exposure to air pollutants. (C) 2010 Elsevier Inc. All rights reserved.

Derivation and external validation of a simple prediction model for the diagnosis of type 2 Diabetes Mellitus in the Brazilian urban population

A risk score model was developed based in a population of 1,224 individuals from the general population without known diabetes aging 35 years or more from an urban Brazilian population sample in order to select individuals who should be screened in subsequent testing and improve the efficacy of public health assurance. External validation was performed in a second, independent, population from a different city ascertained through a similar epidemiological protocol. The risk score was developed by multiple logistic regression and model performance and cutoff values were derived from a receiver operating characteristic curve. Model`s capacity of predicting fasting blood glucose levels was tested analyzing data from a 5-year follow-up protocol conducted in the general population. Items independently and significantly associated with diabetes were age, BMI and known hypertension. Sensitivity, specificity and proportion of further testing necessary for the best cutoff value were 75.9, 66.9 and 37.2%, respectively. External validation confirmed the model`s adequacy (AUC equal to 0.72). Finally, model score was also capable of predicting fasting blood glucose progression in non-diabetic individuals in a 5-year follow-up period. In conclusion, this simple diabetes risk score was able to identify individuals with an increased likelihood of having diabetes and it can be used to stratify subpopulations in which performing of subsequent tests is necessary and probably cost-effective.

Metabolic syndrome determinants in an urban population from Brazil: Social class and gender-specific interaction

Introduction: The metabolic syndrome (MS) is characterized by multiple cardiovascular risk factors such as central obesity, arterial hypertension, dislipidemia and hyperinsulinemia and is associated with a higher incidence of cardiovascular events and mortality. The aim of the present work is to describe the prevalence of MS in an urban population from a highly admixed developing country and to characterize the different correlations between this diagnosis, cardiovascular risk factors and demographic variables distributed in this population. Materials and methods: A cross-sectional study of risk factors for cardiovascular diseases was performed in the urban population of Vitoria, Brazil (n= 1507). Major cardiovascular risk factors such as smoking habits, alcohol intake, amount of physical activity, diabetes and hypertension were inquired. Blood biochemical assays were performed by standard techniques in 12 h fasting blood sample and Metabolic Syndrome (MS) was characterizes following the ATP III criteria. Results: The analysis of 1507 individuals showed a 25.43% general prevalence of MS without any significant difference between sexes, but a clear relation of the prevalence with progressing age (p=<0.0001). Even though both sexes showed similar prevalence rates, distribution of risk factors that defined MS was different between men and women, with the prevalence of hypertension, fasting hyperglycemia and hypertriglyceridemia being higher in men. Race was not an important risk factor for MS in this population as opposed to social economic class that was highly associated with the risk of MS in women as their social class was lower, but not in men. Conclusion: This cross-sectional study from a large urban population in Brazil showed a high general prevalence of MS (25.4%), which is increased as the population becomes older (especially in women) and poorer. Although prevalence was very similar in both genders, the frequency of components defining the syndrome varied greatly amongst them. In particular, a significant interaction between gender and social class was observed and may shed light in our understanding of the complex interplay between demographic and biological risk factors for metabolic syndrome. (C) 2007 Elsevier Ireland Ltd. All rights reserved.

Genetic algorithms for continuous optimization problems - a concept of parameter-space size adjustment

The concept of parameter-space size adjustment is pn,posed in order to enable successful application of genetic algorithms to continuous optimization problems. Performance of genetic algorithms with six different combinations of selection and reproduction mechanisms, with and without parameter-space size adjustment, were severely tested on eleven multiminima test functions. An algorithm with the best performance was employed for the determination of the model parameters of the optical constants of Pt, Ni and Cr.