High temperature ferromagnetism of Li-doped vanadium oxide nanotubes

The nature of a puzzling high temperature ferromagnetism of doped mixed-valent vanadium oxide nanotubes reported earlier by Krusin-Elbaum et al., Nature 431 (2004) 672, has been addressed by static magnetization, muon spin relaxation, nuclear magnetic and electron spin resonance spectroscopy techniques. A precise control of the charge doping was achieved by electrochemical Li intercalation. We find that it provides excess electrons, thereby increasing the number of interacting magnetic vanadium sites, and, at a certain doping level, yields a ferromagnetic-like response persisting up to room temperature. Thus we confirm the surprising previous results on the samples prepared by a completely different intercalation method. Moreover our spectroscopic data provide first ample evidence for the bulk nature of the effect. In particular, they enable a conclusion that the Li nucleates superparamagnetic nanosize spin clusters around the intercalation site which are responsible for the unusual high temperature ferromagnetism of vanadium oxide nanotubes.Comment: with some amendments published in Europhysics Letters (EPL) 88 (2009) 57002; http://epljournal.edpsciences.or

Associations between physical fitness and adiposity among school-age children from Monteria, Colombia

Los niveles bajos de condición física se han asociado con adiposidad elevada. Ambas condiciones pueden predecir alteraciones cardiovasculares y metabólicas. El objetivo fue analizar la relación entre la condición física y los indicadores antropométricos de adiposidad. Estudio transversal, en 534 escolares de 6 a 12 años de edad del municipio de Montería. Se midió la condición cardiorrespiratoria (CCR), flexibilidad, fuerza explosiva de miembros inferiores (FEMI), fuerza resistencia abdominal (FRA), Índice de Masa Corporal (IMC), masa adiposa (PMA), y perímetro abdominal (PA). Las asociaciones entre adiposidad y la condición física se analizaron con modelos de regresión logística. Se encontró que el sobrepeso está asociado a baja CCR (ORa = 2,7, p<0,0001); el PA elevado está asociado a baja FRA (ORa = 2,2, p<0,02), y a baja CCR (ORa = 3,3, p<0,001); el PMA elevado está asociado a baja CCR (ORa = 2,7, p<0,0001). Conclusión, la condición física está asociada a la adiposidadLow physical fitness levels have been associated with elevated adiposity. Both conditions may predict cardiovascular and metabolic alterations. The objective was to analyze the associations between health-related physical fitness and adipose. A cross-sectional study in 534 school-age children aged 6-12 in Monteria, Colombia. Measurements included cardiorespiratory fitness (CCR), flexibility, explosive strength of lower limbs (FEMI), abdominal strength endurance (ASE), body mass index (BMI), percentage of adipose mass (PAM), and waist circumference (WC). The associations between adiposity and physical fitness were calculated by logistic regression models. Results indicate that overweight is associated with low CCR (aOR = 2.7, p<0.0001). Elevated PA was associated with low ASE (aOR = 2.2, p<0.02), and with low CCR (aOR = 3.3, p<0.001). Elevated PMA was associated with low CCR (aOR=2.7, p<0.0001). In conclusion, physical fitness is associated with adiposity

A wetting and drying scheme for ROMS

This paper is not subject to U.S. copyright. The definitive version was published in Computers & Geosciences 58 (2013): 54-61, doi:10.1016/j.cageo.2013.05.004.The processes of wetting and drying have many important physical and biological impacts on shallow water systems. Inundation and dewatering effects on coastal mud flats and beaches occur on various time scales ranging from storm surge, periodic rise and fall of the tide, to infragravity wave motions. To correctly simulate these physical processes with a numerical model requires the capability of the computational cells to become inundated and dewatered. In this paper, we describe a method for wetting and drying based on an approach consistent with a cell-face blocking algorithm. The method allows water to always flow into any cell, but prevents outflow from a cell when the total depth in that cell is less than a user defined critical value. We describe the method, the implementation into the three-dimensional Regional Oceanographic Modeling System (ROMS), and exhibit the new capability under three scenarios: an analytical expression for shallow water flows, a dam break test case, and a realistic application to part of a wetland area along the Georgia Coast, USA.We acknowledge support for studies demonstrated in this manuscript that were supported by the National Science Foundation,Division of Industrial Innovation and Partnerships (IIP)under the 3470Z. Defne etal./ Renewable Energy 36(2011)3461e3471 Partnerships for Innovation Program Grant IIP-0332613,and from the Strategic Energy Institute at Georgia Institute of Technology via a Creating Energy Options grant and the 104B Georgia Water Resources Institute Funding Program,and also by the Department of Energy,Wind and Hydropower Technologies Program award number DE-FG36-08GO18174 and by the state of Georgia

Entanglement and Timing-Based Mechanisms in the Coherent Control of Scattering Processes

The coherent control of scattering processes is considered, with electron impact dissociation of H$_2^+$ used as an example. The physical mechanism underlying coherently controlled stationary state scattering is exposed by analyzing a control scenario that relies on previously established entanglement requirements between the scattering partners. Specifically, initial state entanglement assures that all collisions in the scattering volume yield the desirable scattering configuration. Scattering is controlled by preparing the particular internal state wave function that leads to the favored collisional configuration in the collision volume. This insight allows coherent control to be extended to the case of time-dependent scattering. Specifically, we identify reactive scattering scenarios using incident wave packets of translational motion where coherent control is operational and initial state entanglement is unnecessary. Both the stationary and time-dependent scenarios incorporate extended coherence features, making them physically distinct. From a theoretical point of view, this work represents a large step forward in the qualitative understanding of coherently controlled reactive scattering. From an experimental viewpoint, it offers an alternative to entanglement-based control schemes. However, both methods present significant challenges to existing experimental technologies

Association between the perceived environment and physical activity among adults in Latin America: a systematic review

BACKGROUND: Activity friendly environments have been identified as promising strategies to increase physical activity levels in the population. Associations between perceived environmental attributes and physical activity in Latin America may vary from those observed in high income countries. The objective of this systematic review is to identify which perceived environmental attributes are associated with physical activity in Latin America. METHODS: Systematic literature search of articles published in English, Portuguese, and Spanish in four databases was conducted (PubMed, Virtual Health Library, EBSCO, and Web of Science). Associations with environmental attributes were analyzed separately for physical activity domains. Fifteen articles were included in the analysis. RESULTS: All studies had cross-sectional designs. The majority of associations were statistically non-significant, and only four associations were found in the unexpected direction. Leisure-time and transport-related physical activity were the domains most frequently included in the studies and had higher number of associations in the expected direction. Leisure-time physical activity showed a convincing association in the expected direction with safety during the day. Transport-related physical activity had a convincing association with presence of street lighting. CONCLUSIONS: This study shows that perceived environmental attributes and their relationship with physical activity appears to be domain, and context specific. In addition, findings from this study show inconsistencies with the information gathered from high-income countries

Percepción de la violencia en niños y niñas de 4to., 5to. y 6to. grado de primaria que asisten a la Escuela Oficial Urbana Mixta Tipo Federación No. 2, 17 de abril de 1763, Villa Nueva.

Interpretó la percepción que tienen los niños y niñas de nivel primario de la violencia. Implementó un programa de prevención de la violencia, se logró promover formas de relación pacíficas y se desarrollar habilidades de comunicación que favorecieron la libre y sana convivencia en la comunidad educativa, se contribuyó en la construcción de una cultura de paz. La investigación fue desarrollada en la Escuela Oficial Urbana Mixta Tipo Federación No.2 “17 de Abril de 1763”, jornada matutina; ubicada en el municipio de Villa Nueva, durante los meses de febrero a junio del año 2014. La muestra estuvo conformada por 46 niños y niñas de 4to., 5to. y 6to. primaria. Para recolectar datos se utilizó la observación participativa, el dibujo técnico, entrevista en profundidad, cuestionario para maestros acerca de percepción de violencia y talleres participativos. Para el análisis estadístico de los resultados se utilizaron: codificación abierta, codificación axial y teorización. Con el programa se logró que, los estudiantes adquirieran conciencia de su realidad y de su responsabilidad, se logró mejores relaciones interpersonales y habilidades sociales asertivas

Magnetic properties of the low-dimensional spin-1/2 magnet \alpha-Cu_2As_2O_7

In this work we study the interplay between the crystal structure and magnetism of the pyroarsenate \alpha-Cu_2As_2O_7 by means of magnetization, heat capacity, electron spin resonance and nuclear magnetic resonance measurements as well as density functional theory (DFT) calculations and quantum Monte Carlo (QMC) simulations. The data reveal that the magnetic Cu-O chains in the crystal structure represent a realization of a quasi-one dimensional (1D) coupled alternating spin-1/2 Heisenberg chain model with relevant pathways through non-magnetic AsO_4 tetrahedra. Owing to residual 3D interactions antiferromagnetic long range ordering at T_N\simeq10K takes place. Application of external magnetic field B along the magnetically easy axis induces the transition to a spin-flop phase at B_{SF}~1.7T (2K). The experimental data suggest that substantial quantum spin fluctuations take place at low magnetic fields in the ordered state. DFT calculations confirm the quasi-one-dimensional nature of the spin lattice, with the leading coupling J_1 within the structural dimers. QMC fits to the magnetic susceptibility evaluate J_1=164K, the weaker intrachain coupling J'_1/J_1 = 0.55, and the effective interchain coupling J_{ic1}/J_1 = 0.20.Comment: Accepted for publication in Physical Review

Bayesian hierarchical clustering for studying cancer gene expression data with unknown statistics

Clustering analysis is an important tool in studying gene expression data. The Bayesian hierarchical clustering (BHC) algorithm can automatically infer the number of clusters and uses Bayesian model selection to improve clustering quality. In this paper, we present an extension of the BHC algorithm. Our Gaussian BHC (GBHC) algorithm represents data as a mixture of Gaussian distributions. It uses normal-gamma distribution as a conjugate prior on the mean and precision of each of the Gaussian components. We tested GBHC over 11 cancer and 3 synthetic datasets. The results on cancer datasets show that in sample clustering, GBHC on average produces a clustering partition that is more concordant with the ground truth than those obtained from other commonly used algorithms. Furthermore, GBHC frequently infers the number of clusters that is often close to the ground truth. In gene clustering, GBHC also produces a clustering partition that is more biologically plausible than several other state-of-the-art methods. This suggests GBHC as an alternative tool for studying gene expression data. The implementation of GBHC is available at https://sites. google.com/site/gaussianbhc

Mental disorders in primary health care: a study of their frequency and diagnosis in four developing countries

1624 patients who were attending primary health facilities in 4 developing countries were examined to determine how many were suffering from mental disorder. Using stringent criteria to establish the presence of psychiatric morbidity, 225 cases were found, indicating an overall frequency of 13·9 %. The great majority of cases were suffering from neurotic illnesses and for most the presenting complaint was of a physical symptom, such as headache, abdominal pain, cough or weakness. The health workers following their normal procedure correctly detected one third of the psychiatric case