High mobility one- and two-dimensional electron systems in nanowire-based quantum heterostructures.

Free-standing semiconductor nanowires in combination with advanced gate-architectures hold an exceptional promise as miniaturized building blocks in future integrated circuits. However, semiconductor nanowires are often corrupted by an increased number of close-by surface states, which are detrimental with respect to their optical and electronic properties. This conceptual challenge hampers their potentials in high-speed electronics and therefore new concepts are needed in order to enhance carrier mobilities. We have introduced a novel type of core-shell nanowire heterostructures that incorporate modulation or remote doping and hence may lead to high-mobility electrons. We demonstrate the validity of such concepts using inelastic light scattering to study single modulation-doped GaAs/Al0.16Ga0.84As core-multishell nanowires grown on silicon. We conclude from a detailed experimental study and theoretical analysis of the observed spin and charge density fluctuations that one- and two-dimensional electron channels are formed in a GaAs coaxial quantum well spatially separated from the donor ions. A total carrier density of about 3 × 10(7) cm(-1) and an electron mobility in the order of 50,000 cm(2)/(V s) are estimated. Spatial mappings of individual GaAs/Al0.16Ga0.84As core-multishell nanowires show inhomogeneous properties along the wires probably related to structural defects. The first demonstration of such unambiguous 1D- and 2D-electron channels and the respective charge carrier properties in these advanced nanowire-based quantum heterostructures is the basis for various novel nanoelectronic and photonic devices.

Recomendaciones nutricionales y alimentarias para una dieta cardiosaludable / Nutrition recommendations and guidelines for a healthy heart diet

A lo largo de las últimas décadas la epidemiología nutricional ha experimentado un importante avance y, en consecuencia, también la evidencia científica sobre la relación dieta-salud. En este trabajo se realiza una profusa revisión sobre los fundamentos epidemiológicos Y de otra índole que sirven de base para formular recomendaciones nutricionales y guías alimentarias para la prevención de las enfermedades cardiovasculares (AU)

Through out the last decades nutritional epidemiology has experienced an important development. As a consequence, the body of scientific evidence relating diet and health has increased as well. In this paper a thorough review of the epidemiological and other kind of sound basis tor the formulation of nutritional recommendations and dietary guidelines for the prevention of cardiovascular disease is presented (AU)

Consumption of bakery products, sweetened soft drinks and yogurt among children aged 6-7 years: association with nutrient intake and overall diet quality.

The present study tests the hypothesis that higher consumption of bakery products, sweetened soft drinks and yogurt is associated with higher intake of energy, saturated fats, sugars and worse overall diet quality among Spanish children. This is a cross-sectional study covering 1112 children aged 6.0-7.0 years in four Spanish cities. Nutrient and food intake were obtained through a food-frequency questionnaire, and overall diet quality calculated using the healthy-eating index (HEI) developed by Kennedy et al. (1995). Standardized methods were used to measure anthropometric variables. Associations of interest were summarized as the difference in nutrient and food consumption between the value of the fifth and the first quintile of consumption (dq) of bakery products, sweetened soft drinks or yogurt, adjusted for energy intake and BMI. Bakery products, sweetened soft drinks and yogurt supplied 15.5, 1.0 and 5.6 % energy intake respectively. Higher consumption of these three foods was associated with greater energy intake (P<0.001), but not with higher BMI. Consumption of bakery products was associated with the proportion of energy derived from intake of total carbohydrates (dq 4.5 %, P<0.001) and sugars (dq 2 %, P<0.001), but did not show association with the HEI. Consumption of sweetened soft drinks was associated with a lower consumption of milk (dq -88 ml, P<0.001) and Ca (dq -175 mg/d, P<0.001), and worse HEI (dq -2, P<0.01). Consumption of yogurt, while associated with higher energy intake from saturated fats (dq 1.77 %, P<0.001) and sugars (dq 2.02 %, P<0.001), showed no association with the HEI. Differences in the intake of nutrients and foods across quintiles of consumption of bakery products, sweetened soft drinks and yogurt were usually very small. We conclude that the impact of the consumption of bakery products, sweetened soft drinks and yogurt on the quality of the diet of Spanish children is only modest, although it may contribute to aggravating certain unhealthy characteristics of their diet, particularly excess energy, saturated fats and sugars. Therefore, consumption of bakery products and sweetened soft drinks should be moderated, and priority given to consumption of low-fat, low-sugar yogurt.