Determination of the Deep Inelastic Contribution to the Generalised Gerasimov-Drell-Hearn Integral for the Proton and Neutron

The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2] for the proton and neutron have been determined from measurements of polarised cross section asymmetries in deep inelastic scattering of 27.5 GeV longitudinally polarised positrons from polarised 1H and 3He internal gas targets. The data were collected in the region above the nucleon resonances in the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the proton the contribution to the generalised Gerasimov-Drell-Hearn integral was found to be substantial and must be included for an accurate determination of the full integral. Furthermore the data are consistent with a QCD next-to-leading order fit based on previous deep inelastic scattering data. Therefore higher twist effects do not appear significant.Comment: 6 pages, 3 figures, 1 table, revte

Observation of a Coherence Length Effect in Exclusive Rho^0 Electroproduction

Exclusive incoherent electroproduction of the rho^0(770) meson from 1H, 2H, 3He, and 14N targets has been studied by the HERMES experiment at squared four-momentum transfer Q**2>0.4 GeV**2 and positron energy loss nu from 9 to 20 GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the nuclear transparency, was found to decrease with increasing coherence length of quark-antiquark fluctuations of the virtual photon. The data provide clear evidence of the interaction of the quark- antiquark fluctuations with the nuclear medium.Comment: RevTeX, 5 pages, 3 figure

Estimation and Mapping of Wet and Dry Mercury Deposition Across Northeastern North America

Whereas many ecosystem characteristics and processes influence mercury accumulation in higher trophic-level organisms, the mercury flux from the atmosphere to a lake and its watershed is a likely factor in potential risk to biota. Atmospheric deposition clearly affects mercury accumulation in soils and lake sediments. Thus, knowledge of spatial patterns in atmospheric deposition may provide information for assessing the relative risk for ecosystems to exhibit excessive biotic mercury contamination. Atmospheric mercury concentrations in aerosol, vapor, and liquid phases from four observation networks were used to estimate regional surface concentration fields. Statistical models were developed to relate sparsely measured mercury vapor and aerosol concentrations to the more commonly measured mercury concentration in precipitation. High spatial resolution deposition velocities for different phases (precipitation, cloud droplets, aerosols, and reactive gaseous mercury (RGM)) were computed using inferential models. An empirical model was developed to estimate gaseous elemental mercury (GEM) deposition. Spatial patterns of estimated total mercury deposition were complex. Generally, deposition was higher in the southwest and lower in the northeast. Elevation, land cover, and proximity to urban areas modified the general pattern. The estimated net GEM and RGM fluxes were each greater than or equal to wet deposition in many areas. Mercury assimilation by plant foliage may provide a substantial input of methyl-mercury (MeHg) to ecosystems.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44443/1/10646_2004_Article_6259.pd

Synthesis and characterisation of fluorescently doped mesoporous nanoparticles for two-photon excitation.

International audienc

Functionalization of two-photon dye-doped mesoporous silica nanoparticles with folic acid. Cytotoxicity studies with folate receptor positive cancer cells.

International audienc

Intenção de mudança de comportamento em adolescentes para a prática de atividades físicas de lazer

O objetivo deste estudo foi investigar a intenção da mudança de comportamento de adolescentes de diferentes níveis socioeconómicos (NSE) para a prática de atividades físicas de lazer, adotando o Modelo Transteorético e a Teoria do Comportamento Planejado (TCP). Foi realizado um estudo transversal com a participação de 416 adolescentes, pertencentes a escolas do ensino médio nas cidades de Belo Horizonte e Contagem/MG, com média de idade de 16,4 ± 1,2 anos. As análises foram feitas utilizando estatísticas descritivas e paramétricas (ANOVA e regressão logística). Os resultados encontrados demonstraram que a maioria dos adolescentes é inativa no lazer, e às variáveis, sexo, atitude e controle percebido são os fatores mais relevantes para classificar o nível de atividade física de lazer, sendo que as variáveis sociais (nível socioeconómico e norma subjetiva) têm pouca importância para predizer a intenção de mudança de comportamento para a prática dessas atividades.El objetivo de este estudio fue investigar la intención de cambiar el comportamiento de los adolescentes de diferentes niveles socioeconómicos (NSE) para la práctica de actividades físicas de ocio, por la que se aprueba el modelo Transteoretico y la teoría de la Conducta Planificada (TCP). Se realizó un estudio transversal con la participación de 416 adolescentes, pertenecientes a las escuelas de enseñanza secundaria de las ciudades de Belo Horizonte y Contagem/MG, con una edad media de 16,4 ±1,2 años. Los análisis se realizaron mediante estadísticas descriptivas y paramétrico (ANOVA y regresión logística), con p The aim of this study was to investigate the intention of behavior changing in adolescents from different socioeconomic status (SES) to leisure physical activities, adopting the transtheoretical model and the Theory of Planned Behavior (TPB). We conducted a cross-sectional study involving 416 adolescents belonging to high schools in the cities of Belo Horizonte and Contagem / MG, with a mean age of 16.4 ± 1.2 years. Analyses were performed using descriptive and parametric statistics (ANOVA and logistic regression). The results show that most of teenagers are inactive during leisure time, and the variables, sex, attitude and perceived control are the most relevant factors to rate the level of leisure physical activity, and social variables (socioeconomic status and standard subjective) are of less importance in predicting the intention to change behavior to practice these activities