First-Principles Study of Substitutional Metal Impurities in Graphene: Structural, Electronic and Magnetic Properties

We present a theoretical study using density functional calculations of the structural, electronic and magnetic properties of 3d transition metal, noble metal and Zn atoms interacting with carbon monovacancies in graphene. We pay special attention to the electronic and magnetic properties of these substitutional impurities and found that they can be fully understood using a simple model based on the hybridization between the states of the metal atom, particularly the d shell, and the defect levels associated with an unreconstructed D3h carbon vacancy. We identify three different regimes associated with the occupation of different carbon-metal hybridized electronic levels: (i) bonding states are completely filled for Sc and Ti, and these impurities are non-magnetic; (ii) the non-bonding d shell is partially occupied for V, Cr and Mn and, correspondingly, these impurties present large and localized spin moments; (iii) antibonding states with increasing carbon character are progressively filled for Co, Ni, the noble metals and Zn. The spin moments of these impurities oscillate between 0 and 1 Bohr magnetons and are increasingly delocalized. The substitutional Zn suffers a Jahn-Teller-like distortion from the C3v symmetry and, as a consequence, has a zero spin moment. Fe occupies a distinct position at the border between regimes (ii) and (iii) and shows a more complex behavior: while is non-magnetic at the level of GGA calculations, its spin moment can be switched on using GGA+U calculations with moderate values of the U parameter.Comment: 13 figures, 4 tables. Submitted to Phys. Rev. B on September 26th, 200

Arsenic Exposure and the Induction of Human Cancers

Arsenic is a metalloid, that is, considered to be a human carcinogen. Millions of individuals worldwide are chronically exposed through drinking water, with consequences ranging from acute toxicities to development of malignancies, such as skin and lung cancer. Despite well-known arsenic-related health effects, the molecular mechanisms involved are not fully understood; however, the arsenic biotransformation process, which includes methylation changes, is thought to play a key role. This paper explores the relationship of arsenic exposure with cancer development and summarizes current knowledge of the potential mechanisms that may contribute to the neoplastic processes observed in arsenic exposed human populations

Pharmacokinetics of β-Lactam Antibiotics:Clues from the Past to Help Discover Long-Acting Oral Drugs in the Future

β-Lactams represent perhaps the most important class of antibiotics yet discovered. However, despite many years of active research, none of the currently approved drugs in this class combine oral activity with long duration of action. Recent developments suggest that new β-lactam antibiotics with such a profile would have utility in the treatment of tuberculosis. Consequently, the historical β-lactam pharmacokinetic data have been compiled and analyzed to identify possible directions and drug discovery strategies aimed toward new β-lactam antibiotics with this profile

Crescimento e acúmulo de nutrientes em plantas de Shorgum bicolor L Moench sob irrigação com águas de diferentes concentrações salinas.

: Em muitas áreas irrigadas do mundo, o suprimento de água de boa qualidade pode não ser suficiente para a manutenção da agricultura irrigada, ou seu custo ser elevado, buscando-se alternativas com o uso de água do lençol freático ou mesmo de drenagem. Todavia, geralmente, essas águas não são de boa qualidade e uma das alternativas para viabilizar seu uso é misturá-las com água de baixa concentração de sais. Assim, o objetivo desse trabalho foi avaliar o desenvolvimento inicial e o acúmulo de sais pelo Shorgum bicolor L Moench, irrigado com água de diferentes concentrações salinas originadas da mistura de águas de qualidade diferentes. O experimento foi realizado em condições de casa de vegetação e os tratamentos foram constituídos da aplicação continuada de água de cacimba, do Rio São Francisco e de diferentes misturas entre elas. As unidades experimentais foram constituídas de sacolas plásticas com capacidade para 1,5 dm-3 de solo e o sorgo utilizado como planta indicadora. Os tratamentos foram dispostos em delineamento experimental inteiramente casualizado, com quatro repetições. O aumento da CEa e da RAS da água de irrigação influenciou no crescimento das plantas, reduzindo a produção de matéria fresca e seca da parte aérea, assim como na altura das plantas e número de folhas. O Na+ foi o elemento mais absorvido pela planta, tendo seu teor e acúmulo na matéria aumentado de forma linear e quadrática, respectivamente, em função da concentração salina da água de rrigação. Palavras-chave: RAS, CE, irrigação, sorg

A causal model of radiating stellar collapse

We find a simple exact model of radiating stellar collapse, with a shear-free and non-accelerating interior matched to a Vaidya exterior. The heat flux is subject to causal thermodynamics, leading to self-consistent determination of the temperature $T$. We solve for $T$ exactly when the mean collision time $\tau_{c}$ is constant, and perturbatively in a more realistic case of variable $\tau_{c}$. Causal thermodynamics predicts temperature behaviour that can differ significantly from the predictions of non-causal theory. In particular, the causal theory gives a higher central temperature and greater temperature gradient.Comment: Latex [ioplppt style] 9 pages; to appear Class. Quantum Gra

The Mediterranean diet protects against waist circumference enlargement in 12Ala carriers for the PPARgamma gene: 2 years' follow-up of 774 subjects at high cardiovascular risk.

The PPARgamma gene regulates insulin sensitivity and adipogenesis. The Pro12Ala polymorphism of this gene has been related to fat accumulation. Our aim was to analyse the effects of a 2-year nutritional intervention with Mediterranean-style diets on adiposity in high-cardiovascular risk patients depending on the Pro12Ala polymorphism of the PPARgamma gene. The population consisted of a substudy (774 high-risk subjects aged 55-80 years) of the Prevención con Dieta Mediterránea (PREDIMED) randomised trial aimed at assessing the effect of the Mediterranean diet for CVD prevention. There were three nutritional intervention groups: two of them of a Mediterranean-style diet and the third was a control group advised to follow a conventional low-fat diet. All the participants were genotyped by PCR-restriction fragment length polymorphism (RFLP). The results showed that carriers of the 12Ala allele allocated to the control group had a statistically significant higher change in waist circumference (adjusted difference coefficient = 2.37 cm; P = 0.014) compared with wild-type subjects after 2 years of nutritional intervention. This adverse effect was not observed among 12Ala carriers allocated to both Mediterranean diet groups. In diabetic patients a statistically significant interaction between Mediterranean diet and the 12Ala allele regarding waist circumference change was observed ( - 5.85 cm; P = 0.003). In conclusion, the Mediterranean diet seems to be able to reduce waist circumference in a high-cardiovascular risk population, reversing the negative effect that the 12Ala allele carriers of the PPARgamma gene appeared to have. The beneficial effect of this dietary pattern seems to be higher among type 2 diabetic subjects

La obesidad y su asociación con los demás factores de riesgo cardiovascular en escolares de Itapetininga, Brasil

BACKGROUND: Paucity of data on childhood obesity and cardiovascular risk in Brazil. OBJECTIVE: To determine the prevalence of hypertension, dyslipidemia, obesity and their correlations in a sample of school children in Itapetininga, State of São Paulo, Brazil. METHODS: Cross-sectional study with systematic collection of anthropometric data (weight, height, waist circumference, BMI and blood pressure levels) and determination of glucose, total cholesterol, LDL, HDL, uric acid, and apolipoproteins A and B in a random sample representative of school children from the public education system in Itapetininga, State of São Paulo. For data analysis, we used population parameters from the NCHS curves (2000), blood pressure categories from NHBPEP (2004), and the serum cholesterol levels proposed by the AHA for children and adolescents (2003). RESULTS: A total of 494 children and adolescents participated in the study. Of these, 11.7% had HBP, 51% increased total cholesterol, 40.5% increased LDL-cholesterol, 8.5% increased triglycerides, and 6.1% low HDL-cholesterol levels. Mean (± standard deviation) TC, HDL-cholesterol, LDL-cholesterol and triglycerides were 172.1(27.9), 48.1(10.0), 105.7(23.1) and 90.9(43.8), respectively. Obesity and overweight were detected in 12.8% and 9.7% of the sample, respectively. Individuals of the obese group had a greater chance of presenting with dyslipidemia and hypertension in comparison with those of the other groups. CONCLUSION: This study supports the hypothesis of different prevalences of excess weight among school children from the public education system of the northeastern and southeastern regions of Brazil, with higher rates in the latter. Additionally, it demonstrates an association of obesity with dyslipidemia and hypertension in that group. In light of the paucity of Brazilian data on this issue, our study provides important data for further comparisons.FUNDAMENTO: La escasez de datos sobre la obesidad infantil y el riesgo cardiovascular en Brasil. OBJETIVO: Determinar la prevalencia de hipertensión, dislipidemia, obesidad y sus correlaciones en una muestra de escolares de Itapetininga-SP. MÉTODOS: Corte transversal con recolección sistematizada de datos antropométricos (peso, altura, cintura, índice de masa corporal y niveles de presión) y dosificaciones de glucosa, colesterol (total y fracciones), ácido úrico y apolipoproteína A y B, en una muestra aleatoria, representativa de escolares del sistema público de Itapetininga-SP. Análisis de los datos utilizando parámetros poblacionales de las curvas del NCHS (2000), categorías de presión arterial del NHBPEP(2004) y categorías de los niveles séricos de colesterol propuestos por la AHA para niños y adolescentes (2003). RESULTADOS: Un total de 494 niños y adolescentes participaron en el estudio. De los participantes, el 11,7% presentó HAS, el 51% presentó aumento del colesterol total, el 40,5% presentó aumento del LDL-colesterol, el 8,5% presentó aumento de los triglicéridos y el 6,1% tuvieron valores bajos de HDL-colesterol. Los promedios (+desviación estándar) del CT, HDL-colesterol, LDL-colesterol y triglicéridos fueron respectivamente 172,1 (27,9), 48,1 (10,0), 105,7 (23,1) y 90,9 (43,8). La obesidad y el sobrepeso se detectaron en el 12,8% y el 9,7% de la muestra, teniendo en cuenta que la obesidad determinó una mayor probabilidad de detectarse la dislipidemia y la hipertensión cuando comparada con los demás grupos. CONCLUSIÓN: Este estudio suministra los argumentos a la hipótesis de una distinta prevalencia de exceso de peso entre escolares del sistema público de las regiones nordeste y sudeste, hallándose mayor en ésta última. Adicionalmente, demuestra una asociación de la obesidad con la dislipidemia y la hipertensión en aquel grupo. Ante la condición incipiente de los datos en el Brasil sobre la cuestión estudiada, nuestro trabajo suministra importantes datos para futuras comparaciones.FUNDAMENTO: A escassez de dados sobre a obesidade infantil e o risco cardiovascular no Brasil. OBJETIVO: Determinar a prevalência de hipertensão, dislipidemia, obesidade e suas correlações em uma amostra de escolares de Itapetininga-SP. MÉTODOS: Corte transversal com coleta sistematizada de dados antropométricos (peso, altura, cintura, índice de massa corporal e níveis pressóricos) e dosagens de glicose, colesterol (total e frações), ácido úrico e apolipoproteina A e B, em uma amostra aleatória, representativa de escolares da rede pública de Itapetininga-SP. Análise dos dados utilizando parâmetros populacionais das curvas do NCHS(2000), categorias de pressão arterial do NHBPEP(2004) e categorias dos níveis séricos de colesterol propostos pela AHA para crianças e adolescentes(2003). RESULTADOS: Um total de 494 crianças e adolescentes participaram do estudo. Dos participantes, 11,7% apresentaram HAS, 51% apresentaram aumento do colesterol total, 40,5% apresentaram aumento do LDL-colesterol, 8,5% apresentaram aumento dos triglicérides e 6,1% tiveram valores baixos de HDL-colesterol. As médias (±desvio padrão) do CT, HDL-colesterol, LDL-colesterol e triglicérides foram respectivamente 172,1(27,9), 48,1(10,0), 105,7(23,1) e 90,9(43,8). A obesidade e o sobrepeso foram detectados em 12,8% e 9,7% da amostra, sendo que a obesidade determinou uma maior chance de se detectar a dislipidemia e a hipertensão quando comparada com os demais grupos. CONCLUSÃO: Este estudo fornece subsídios para a hipótese de uma distinta prevalência de excesso de peso entre escolares da rede pública das regiões nordeste e sudeste, maior nesta última. Adicionalmente, demonstra uma associação da obesidade com a dislipidemia e a hipertensão naquele grupo. Diante da incipiência de dados no Brasil sobre a questão estudada, o nosso trabalho fornece dados importantes para futuras comparações.Universidade de São Paulo Faculdade de Medicina Hospital das ClínicasUniversidade Federal de São Paulo (UNIFESP) Departamento de MedicinaUNIFESP, Depto. de MedicinaSciEL

Voltage dip generator for testing wind turbines connected to electrical networks

This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time–voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device

The NUHM2 after LHC Run 1

We make a frequentist analysis of the parameter space of the NUHM2, in which the soft supersymmetry (SUSY)-breaking contributions to the masses of the two Higgs multiplets, $m^2_{H_{u,d}}$, vary independently from the universal soft SUSY-breaking contributions $m^2_0$ to the masses of squarks and sleptons. Our analysis uses the MultiNest sampling algorithm with over $4 \times 10^8$ points to sample the NUHM2 parameter space. It includes the ATLAS and CMS Higgs mass measurements as well as their searches for supersymmetric jets + MET signals using the full LHC Run~1 data, the measurements of $B_s \to \mu^+ \mu^-$ by LHCb and CMS together with other B-physics observables, electroweak precision observables and the XENON100 and LUX searches for spin-independent dark matter scattering. We find that the preferred regions of the NUHM2 parameter space have negative SUSY-breaking scalar masses squared for squarks and sleptons, $m_0^2 < 0$, as well as $m^2_{H_u} < m^2_{H_d} < 0$. The tension present in the CMSSM and NUHM1 between the supersymmetric interpretation of $g_\mu - 2$ and the absence to date of SUSY at the LHC is not significantly alleviated in the NUHM2. We find that the minimum $\chi^2 = 32.5$ with 21 degrees of freedom (dof) in the NUHM2, to be compared with $\chi^2/{\rm dof} = 35.0/23$ in the CMSSM, and $\chi^2/{\rm dof} = 32.7/22$ in the NUHM1. We find that the one-dimensional likelihood functions for sparticle masses and other observables are similar to those found previously in the CMSSM and NUHM1.Comment: 20 pages latex, 13 figure