Surface excitations in the modelling of electron transport for electron- beam-induced deposition experiments

The aim of the present overview article is to raise awareness of an essential aspect that is usually not accounted for in the modelling of electron transport for focused-electron-beam-induced deposition (FEBID) of nanostructures: surface excitations are on the one hand responsible for a sizeable fraction of the intensity in reflection-electron-energy-loss spectra for primary electron energies of up to a few keV and, on the other hand, they play a key role in the emission of secondary electrons from solids, regardless of the primary energy. In this overview work we present a general perspective of recent works on the subject of surface excitations and on low-energy electron transport, highlighting the most relevant aspects for the modelling of electron transport in FEBID simulations.Comment: 17 pages, 5 figure

Simulation of electron transport in electron beam induced deposition of nanostructures

We present a numerical investigation of energy and charge distributions during electron-beam-induced growth of W nanostructures on SiO2 substrates using Monte Carlo simulation of electron transport. This study gives a quantitative insight into the deposition of energy and charge in the substrate and in already existing metallic nanostructures in the presence of the electron beam. We analyze electron trajectories, inelastic mean free paths, and distribution of backscattered electrons in different deposit compositions and depths. We find that, while in the early stages of the nanostructure growth a significant fraction of electron trajectories still interact with the substrate, as the nanostructure becomes thicker the transport takes place almost exclusively in the nanostructure. In particular, a larger deposit density leads to enhanced electron backscattering. This work shows how mesoscopic radiation-transport techniques can contribute to a model which addresses the multi-scale nature of the electron-beam-induced deposition (EBID) process. Furthermore, similar simulations can aid in understanding the role played by backscattered electrons and emitted secondary electrons in the change of structural properties of nanostructured materials during post-growth electron-beam treatments.Comment: 22 pages, 14 figures, 1 tabl

Milk, from medicine to food in Mediterranean Europe: Catalonia, 19th-20th centuries.

The spread of milk consumption was a significant change in the diet of Europeans, however it is one that has not been greatly studied with regard to the populations of Mediterranean Europe. In this article we shall analyse the main circumstances that conditioned that process in Catalonia between the middle of the 19th century and 1936. In our study we shall argue that the consumption of milk in this area was only relevant in the 19th century in situations of illness or old age, and that it subsequently increased and acquired a new significance as a result of various factors. In particular, we shall emphasise: (a) the scientific advances in microbiology and nutrition, (b) the activities carried out by doctors and various public institutions to promote the consumption of fresh milk, and (c) the technological innovations in the milk producing sector. In Appendix 1 we show two maps representing the main territorial references that we shall mention.

Alimentació i nivells de vida : algunes reflexions sobre la transició nutricional a l'Europa occidental

Els canvis en la dieta durant els segles XIX i XX, han atret l'atenció de nombrosos investigadors des de la dècada de 1970 i el seu estudi ha acabat esdevenint, en els darrers anys, una de les principals àrees de recerca de disciplines científiques molt diverses. En aquest breu assaig farem unes reflexions molt generals sobre les interpretacions que es proposen més sovint des de l'Economia i la Història Econòmica de l'evolució del consum de proteïnes animals a les societats europees occidentals, des de la segona meitat del segle XIX

El consumo de leche fresca en Cataluña entre mediados del siglo XIX y 1935 : la difusión de un nuevo alimento

La difusión del consumo de leche fresca fue un cambio significativo en la dieta de los europeos, pero que ha sido poco estudiado con respecto a las poblaciones de la Europa Mediterránea. En este artículo analizaremos las principales circunstancias que condicionaron alquel proceso en Cataluña entre mediados del siglo XIX y 1936. En nuestra exposición argumentaremos que el consumo de leche en aquella zona sólo era relevante en el siglo XIX en situaciones de enfermedad o vejez, y que después aumentó y adquirió un nuevo significado como resultado de varios factores. En especial destacaremos: (a) los progresos científicos en microbiología y nutrición, (b) las actividades que realizaron los médicos y diversas instituciones públicas para fomentar el consumo de leche fresca, y (c) las innovaciones tecnológicas en el sector lechero

Variaciones regionales de los precios de consumo y de las dietas en España, en los inicios de la transición demográfica

Las estadísticas de precios y, en particular, las de alimentos son mucho más abundantes que las de consumo. Este artículo propone utilizar estas estadísticas para analizar las variaciones cualitativas en el consumo y, más concretamente, la composición de la dieta, una variable de difícil observación, pero con notables implicaciones en la evolución de las condiciones de vida, salud y mortalidad de las poblaciones. Concretamente, se han escogido los años comprendidos entre 1910 y 1912, en un periodo de importantes cambios en la mortalidad española, para analizar la variación provincial en los niveles y en las estructuras de precios al consumo. Los índices de precios relativos estimados sugieren que las diferencias regionales en la composición de las dietas eran muy significativas y que se deben tener en cuenta en los análisis de los niveles de vida y de mortalidad.Price statistics and, in particular, food price statistics are much more abundant that those of consumption. In this article we use price statistics to analyze the qualitative variations in consumption and, specifically, the diet composition, a variable which is difficult to observe, but has remarkable implications in the evolution of living standards, health and mortality. Our analysis focuses on the years between 1910 and 1912, in a period of important changes in Spanish mortality, in order to analyze the provincial variation in the level and structure of food prices. The estimated relative price indexes suggest significant regional differences in diets which should be taken into account in living standards and mortality studies

Aspectos políticos y científicos del modelo de la transición nutricional: evaluación crítica y nuevos desarrollos

This article examines the origin and early development of the demographic, epidemiological and nutrition transition models, which were defined in order to explain the evolution of biological living standards of the population, during the different phases of the modern economic growth. In particular, the paper shows that those models were developed from the changing processes observed in European countries, and that political factors were important in its original formulation. The paper also shows that rent initially played a very prominent place as an explanatory variable of these processes of transition, but especially in the case of the Nutrition Transition Model. More recent research, however, the model also considers other variables (environmental, institutional and cultural, scientific advances in nutrition and health). Finally, the article points out the main lines of research that are taking place on the nutrition transition, and the main problems they face, especially with regard to the possibility of making forecasts