Molecular dynamics study of nanoconfined TIP4P/2005 water: how confinement and temperature affect diffusion and viscosity.

In the past few decades great effort has been devoted to the study of water confined in hydrophobic geometries at the nanoscale (tubes and slit pores) due to the multiple technological applications of such systems, ranging from drug delivery to water desalination devices. To our knowledge, neither numerical/theoretical nor experimental approaches have so far reached a consensual understanding of structural and transport properties of water under these conditions. In this work, we present molecular dynamics simulations of TIP4P/2005 water under different nanoconfinements (slit pores or nanotubes, with two degrees of hydrophobicity) within a wide temperature range. It has been found that water is more structured near the less hydrophobic walls, independently of the confining geometries. Meanwhile, we observe an enhanced diffusion coefficient of water in both hydrophobic nanotubes. Finally, we propose a confined Stokes-Einstein relation to obtain the viscosity from diffusivity, whose result strongly differs from the Green-Kubo expression that has been used in previous works. While viscosity computed with the Green-Kubo formula (applied for anisotropic and confined systems) strongly differs from that of the bulk, viscosity computed with the confined Stokes-Einstein relation is not so much affected by the confinement, independently of its geometry. We discuss the shortcomings of both approaches, which could explain this discrepancy.

Maternal BMI and migration status as predictors of childhood obesity in Mexico.

OBJECTIVE: To assess the association of maternal migration to Baja California, body mass index (BMI) status, children's perceived food insecurity, and childhood lifestyle behaviors with overweight (BMI > 85% ile), obesity (BMI > 95% ile) and abdominal obesity (Waist Circumference > 90% ile). METHODS: Convenience sampling methods were used to recruit a cross-sectional sample of 4th, 5th and 6th grade children and their parents at Tijuana and Tecate Public Schools. Children's and parents' weights and heights were measured. Children were considered to have migrant parents if parents were not born in Baja California. RESULTS: One hundred and twenty-two children and their parents were recruited. The mean age of the children was 10.1 ± 1.0 years. Forty nine per cent of children were overweight or obese. Children with obese parents (BMI > 30) had greater odds of being obese, Odds Ratio (OR) 4.9 (95% Confidence Interval (CI), 1.2-19, p = 0.03). Children with migrant parents had greater odds of being obese, OR= 3.7 (95% CI, 1.6-8.3), p = 0.01) and of having abdominal obesity, OR = 3.2 (95% CI, 1.4-7.1, p = 0.01). Children from migrant parents have greater risk of higher consumption of potato chips, OR = 8.0 (95% CI, 2.1-29.1, p = 0.01). Children from non-migrant parents had greater odds of being at risk of hunger. CONCLUSIONS: Parental obesity and migration are associated with increased risk of obesity among Mexican children. Children whose parents were born in Baja California have greater odds of being at risk of hunger. Further studies should evaluate the role of migration on risk for childhood obesity.

Perception of body size among Mexican teachers and parents.

Obesity in Mexico has reached epidemic proportions; and body image and body satisfaction might be culturally related. Body dissatisfaction has been related to low self-esteem. The aim of this study was to assess the range of perception among Mexican teachers and parents of the ideal body size of adults, boys and girls. Two-hundred and five teachers and eighty parents from Tijuana and Tecate schools participated in the study. Participants were asked to indicate the ideal body size for each group, as well as their own ideal body size. Average perception of ideal body weight for adults 35 to 45 years of age was 4.0 +/- 0.84. Average perception for boys and girls was 4.6. Positive correlations were shown between self-perception of body size and body mass index (0.62, P < 001), waist circumference (0.55, P < 0.001). Self-perception of body size was associated with perception of ideal body size for boys (0.23, P 0.001) and girls (0.22, P < 0.001), but BMI was not associated to perception of ideal body size for boys and girls. These results suggest that teachers and parents should be taught to more accurately assess excess weight status and to initiate action to prevent or correct excessive weight among children and adults.

Sindrome de zollinger-ellison: análisis de tres casos / Zollinger-ellison syndrome: analysis of three case

Los gastrinomas están entre los tumores neuroendocrinos pancreáticos más frecuentes, y el 60 por ciento son malignos. Al momento del diagnóstico el 50 por ciento ya presentan matástasis aunque se trata de lesiones de bajo grado de malignidad, y el 60 por ciento de estas lesiones se originan en lugares extrapancreáticos. Los tres casos que se analizaron demostraron la utilidad de los niveles de gastrina seriados, la ecoendoscopia y la sintigrafía para receptores de somatostatina marcados con Indio 111 en la detección de lesiones metastásicas