Bilayer manganites: polarons in the midst of a metallic breakdown

The exact nature of the low temperature electronic phase of the manganite materials family, and hence the origin of their colossal magnetoresistant (CMR) effect, is still under heavy debate. By combining new photoemission and tunneling data, we show that in La{2-2x}Sr{1+2x}Mn2O7 the polaronic degrees of freedom win out across the CMR region of the phase diagram. This means that the generic ground state is that of a system in which strong electron-lattice interactions result in vanishing coherent quasi-particle spectral weight at the Fermi level for all locations in k-space. The incoherence of the charge carriers offers a unifying explanation for the anomalous charge-carrier dynamics seen in transport, optics and electron spectroscopic data. The stacking number N is the key factor for true metallic behavior, as an intergrowth-driven breakdown of the polaronic domination to give a metal possessing a traditional Fermi surface is seen in the bilayer system.Comment: 7 pages, 2 figures, includes supplementary informatio

Sensibilidade e especificidade no diagnóstico de hipertensão por diferentes métodos

OBJECTIVE: To evaluate sensitivity and specificity of different protocols for blood pressure measurement for the diagnosis of hypertension in adults. METHODS: Cross-sectional study conducted in a non-probabilistic sample of 250 public servants of both sexes aged 35 to 74 years in Vitória, southeastern Brazil, between 2008 and 2010. The participants had their blood pressure measured using three different methods: clinic measurement, self-measured and 24-hour ambulatory measurement. They were all interviewed to obtain sociodemographic information and had their anthropometric data (weight, height, waist circumference) collected. Clinic measurement and self-measured were analyzed against the gold standard ambulatory measurement. Measures of diagnostic performance (sensitivity, specificity, accuracy and positive and negative predictive values) were calculated. The Bland & Altman method was used to evaluate agreement between ambulatory measurement (standard deviation for daytime measurements) and self-measured (standard deviation of four measurements). A 5% significance level was used for all analyses. RESULTS: Self-measured blood pressure showed higher sensitivity (S=84%, 95%CI 75;93) and overall accuracy (0.817, pOBJETIVO: Avaliar a sensibilidade e a especificidade de diferentes protocolos de medida da pressão arterial para o diagnóstico da hipertensão em adultos. MÉTODOS: Estudo transversal com amostra não probabilística de 250 funcionários de ambos os sexos de instituição pública na faixa etária de 35 a 74 anos em Vitória, ES, entre 2008 e 2010. Os participantes tiveram suas pressões arteriais aferidas por três métodos: medida clínica, automedida e medida ambulatorial por 24 horas. Foram coletados dados antropométricos (peso, estatura e circunferências) e realizada entrevista. Os métodos foram confrontados e analisados em relação à medida ambulatorial 24 h (padrão-ouro). Foram calculadas as medidas de desempenho diagnóstico: sensibilidade, especificidade, valores preditivos positivos e negativos e acurácia. A metodologia de Bland & Altman foi utilizada para verificar a concordância entre a variabilidade pressórica na medida ambulatorial (desvio-padrão relativo ao período diurno) e a variabilidade pressórica na automedida (desvio-padrão das quatro medidas). Adotou-se nível de significância de 5% para todos os testes. RESULTADOS: A automedida apresentou maior sensibilidade (S = 84%; IC95%: 75;93) e acurácia global (0,817; p < 0,001) no diagnóstico da hipertensão que a medida clínica (S = 79%; IC95%: 73;86 e AG = 0,815; p < 0,001). Apesar da forte correlação com o método de medida ambulatorial durante a vigília (r = 0,843; p = 0,000), a automedida não mostrou boa concordância com o referido método para a medida sistólica (viés = 5,82; IC95%: 4,49;7,15). Foram identificados sete (2,8%) indivíduos com hipertensão do avental branco, 26 (10,4%) com hipertensão mascarada e 46 (18,4%) com efeito do avental branco. CONCLUSÕES: Os resultados sugerem que a automedida apresenta sensibilidade superior à medida clínica para identificar verdadeiros hipertensos na população. Os valores de predição negativa encontrados confirmam a superioridade da automedida em relação à medida clínica no que tange à capacidade do teste em apontar os indivíduos verdadeiramente normotensos. Contudo, não pode substituir a medida clínica, que ainda é o método mais fidedigno.OBJETIVO: Evaluar la sensibilidad y la especificidad de diferentes protocolos de medida de la presión arterial para el diagnóstico de la hipertensión en adultos. MÉTODOS: Estudio transversal con muestra no probabilística de 250 funcionarios de ambos sexos de institución pública en el grupo etáreo de 35 a 74 años en Vitoria, Sureste de Brasil, entre 2008 y 2010. Los participantes tuvieron sus presiones arteriales medidas por tres métodos: medida clínica, automedida y medida por ambulatorio por 24 horas. Se colectaron datos antropométricos (peso, estatura y circunferencias) y se realizó entrevista. Los métodos fueron confrontados y analizados con relación a la medida por ambulatorio 24h (patrón-oro). Se calcularon las medidas de desempeño diagnóstico: sensibilidad, especificidad, valores predictivos positivos y negativos y precisión. La metodología de Bland & Altman fue utilizada para verificar la concordancia entre la variable presórica en la automedida (desviación estándar de las cuatro medidas). Se adoptó nivel de 5% de significancia para todas las pruebas. RESULTADOS: La automedida presentó mayor sensibilidad (S=84%; IC95%: 75;93) y precisión global (0,817;

Nutritional status of pre-school children from low income families

<p>Abstract</p> <p>Background</p> <p>We evaluated growth and nutritional status of preschool children between 2 and 6 years old from low income families from 14 daycare centers.</p> <p>Methods</p> <p>Cross-sectional study with 1544 children from daycare centers of Santo Andre, Brazil. Body weight (W), height (H) and body mass index (BMI) were classified according to the 2000 National Center for Health Statistics (CDC/NCHS). Cutoff points for nutritional disorders: -2 z scores and 2.5 and 10 percentiles for malnutrition risk, 85 to 95 percentile for overweight and above BMI 95 percentile for obesity. Stepwise Forward Regression method was used including age, gender, birth weight, breastfeeding duration, age of mother at birth and period of time they attended the daycare center.</p> <p>Results</p> <p>Children presented mean z scores of H, W and BMI above the median of the CDC/NCHS reference. Girls were taller and heavier than boys, while we observed similar BMI between both genders. The z scores tended to rise with age. A Pearson Coefficient of Correlation of 0.89 for W, 0.93 for H and 0.95 for BMI was documented indicating positive association of age with weight, height and BMI. The frequency of children below -2 z scores was lower than expected: 1.5% for W, 1.75% for H and 0% for BMI, which suggests that there were no malnourished children. The other extremity of the distribution evidenced prevalence of overweight and obesity of 16.8% and 10.8%, respectively.</p> <p>Conclusion</p> <p>Low income preschool children are in an advanced stage of nutritional transition with a high prevalence of overweight.</p

European propolis is highly active against trypanosomatids including Crithidia fasciculata.

Extracts of 35 samples of European propolis were tested against wild type and resistant strains of the protozoal pathogens Trypanosoma brucei, Trypanosoma congolense and Leishmania mexicana. The extracts were also tested against Crithidia fasciculata a close relative of Crithidia mellificae, a parasite of bees. Crithidia, Trypanosoma and Leishmania are all members of the order Kinetoplastida. High levels of activity were obtained for all the samples with the levels of activity varying across the sample set. The highest levels of activity were found against L. mexicana. The propolis samples were profiled by using liquid chromatography with high resolution mass spectrometry (LC-MS) and principal components analysis (PCA) of the data obtained indicated there was a wide variation in the composition of the propolis samples. Orthogonal partial least squares (OPLS) associated a butyrate ester of pinobanksin with high activity against T. brucei whereas in the case of T. congolense high activity was associated with methyl ethers of chrysin and pinobanksin. In the case of C. fasciculata highest activity was associated with methyl ethers of galangin and pinobanksin. OPLS modelling of the activities against L. mexicana using the mass spectrometry produced a less successful model suggesting a wider range of active components

Long-term carbon sink in Borneo's forests halted by drought and vulnerable to edge effects

Less than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha‾¹ per year (95% CI 0.14—0.72, mean period 1988-2010) above-ground live biomass. These results closely match those from African and Amazonian plot networks, suggesting that the world's remaining intact tropical forests are now en masse out-of-equilibrium. Although both pan-tropical and long-term, the sink in remaining intact forests appears vulnerable to climate and land use changes. Across Borneo the 1997-1998 El Niño drought temporarily halted the carbon sink by increasing tree mortality, while fragmentation persistently offset the sink and turned many edge-affected forests into a carbon source to the atmosphere