Micro-beam and pulsed laser beam techniques for the micro-fabrication of diamond surface and bulk structures

Micro-fabrication in diamond is involved in a wide set of emerging technologies, exploiting the exceptional characteristics of diamond for application in bio-physics, photonics, radiation detection. Micro ion-beam irradiation and pulsed laser irradiation are complementary techniques, which permit the implementation of complex geometries, by modification and functionalization of surface and/or bulk material, modifying the optical, electrical and mechanical characteristics of the material. In this article we summarize the work done in Florence (Italy) concerning ion beam and pulsed laser beam micro-fabrication in diamond.Comment: 14 pages, 5 figure

The impact of food assistance on food insecure populations during conflict: evidence from a quasi-experiment in Mali

Mali, a vast landlocked country at the heart of West Africa in the Sahel region, is one of the least developed and most food insecure countries in the world. Mali suffered from a series of political, constitutional and military crises since January 2012, including the loss of government control of northern territories from April 2012 until January 2013. A range of humanitarian aid interventions were scaled up in response to these complex crises. In this study, we exploit data from a unique pre-crisis baseline to evaluate the impact of humanitarian aid on the food security of rural populations. We design a quasi-experimental study based on two survey rounds, five years apart, in the Mopti region in Northern Mali. Data was collected from 66 communities randomly selected from within food-insecure districts. Study outcomes include household expenditures and food consumption and a proxy for child nutritional status (height measurements). We estimate program impact by combining propensity score matching and difference-in-difference. Food assistance was found to increase household non-food and food expenditures and micro-nutrient availability. Disaggregating by degree of conflict exposure showed that the effects on children’s height and caloric and micro-nutrient consumption were mostly concentrated in areas not in the immediate vicinity of the conflict, unlike the increase in food expenditures that were driven by households located in close proximity to armed groups. The effects were also concentrated on households receiving at least two forms of food assistance. In villages where armed groups were present, food assistance improved household zinc consumption and also appeared to support food expenditures. Food transfers are thus found to exert a protective effect among food insecure population in conflict context

Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions

An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium emission has been evidenced and attributed both to entrance channel effects favoured by the cluster nature of reaction partners and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.Comment: 4 pages, 2 figures, Contribution to conference proceedings of the 25th International Nuclear Physics Conference (INPC 2013

Examination of Fluconazole-Induced Alopecia in an Animal Model and Human Cohort.

Fluconazole-induced alopecia is a significant problem for patients receiving long-term therapy. We evaluated the hair cycle changes of fluconazole in a rat model and investigated potential molecular mechanisms. Plasma and tissue levels of retinoic acid were not found to be causal. Human patients with alopecia attributed to fluconazole also underwent detailed assessment and in both our murine model and human cohort fluconazole induced telogen effluvium. Future work further examining the mechanism of fluconazole-induced alopecia should be undertaken

Response of microchannel plates to single particles and to electromagnetic showers

We report on the response of microchannel plates (MCPs) to single relativistic particles and to electromagnetic showers. Particle detection by means of secondary emission of electrons at the MCP surface has long been proposed and is used extensively in ion time-of-flight mass spectrometers. What has not been investigated in depth is their use to detect the ionizing component of showers. The time resolution of MCPs exceeds anything that has been previously used in calorimeters and, if exploited effectively, could aid in the event reconstruction at high luminosity colliders. Several prototypes of photodetectors with the amplification stage based on MCPs were exposed to cosmic rays and to 491 MeV electrons at the INFN-LNF Beam-Test Facility. The time resolution and the efficiency of the MCPs are measured as a function of the particle multiplicity, and the results used to model the response to high-energy showers.Comment: Paper submitted to NIM

Response of microchannel plates in ionization mode to single particles and electromagnetic showers

Hundreds of concurrent collisions per bunch crossing are expected at future hadron colliders. Precision timing calorimetry has been advocated as a way to mitigate the pileup effects and, thanks to their excellent time resolution, microchannel plates (MCPs) are good candidate detectors for this goal. We report on the response of MCPs, used as secondary emission detectors, to single relativistic particles and to electromagnetic showers. Several prototypes, with different geometries and characteristics, were exposed to particle beams at the INFN-LNF Beam Test Facility and at CERN. Their time resolution and efficiency are measured for single particles and as a function of the multiplicity of particles. Efficiencies between 50% and 90% to single relativistic particles are reached, and up to 100% in presence of a large number of particles. Time resolutions between 20ps and 30ps are obtained.Comment: 20 pages, 9 figures. Paper submitted to NIM

Examination of isospin effects in multi-dimensional Langevin fission dynamics

One-dimensional and three-dimensional dynamical fission calculations based on Langevin equations are performed for the compound nuclei Pb-194, Pb-200, Pb-206, Hg-182, and Hg-204 to investigate the influence of the compound nucleus isospin on the prescission particle multiplicities and oil the fission fragment mass-energy distribution It is found that the prescission neutron, proton, and alpha particle multiplicities have approximately the same sensitivity to the dissipation strength for a given nucleus This is at variance with Conclusions of recent papers The sensitivity of the calculated prescission particle Multiplicities to the dissipation strength becomes higher with decreasing isospin of fissioning compound nucleus, and the increase of prescission particle multiplicities could reach 200%, when the reduction coefficient of one-body viscosity k(s) increases from 0 1 to 1, for the most neutron deficient nuclei considered The variances of fission fragment mass and kinetic energy distributions are less sensitive to the change of dissipation strength than the prescission light particle multiplicities A comparison to experimental data concerning Pb-200 nucleus is also presented

Trade-offs in costs, diet quality and regional diversity: An analysis of the nutritional value of school meals in Ghana

There is a paucity of studies in the literature regarding the nutrient content and costs of school meals provided across West Africa. Where studies exist, comparative analysis is constrained by inconsistencies in measurements of portion sizes, meal composition and costs. This study reviews the available literature on the nutritional value of school meals in West Africa and reinterprets the meal contributions to the recommended daily intake for the 9-10 year old age group. The nutritional content of school meals from the Ghana School Feeding Programme is then analyzed through a linear modelling analysis of menus obtained from 34 districts in the country. Meal composition and associated nutritional content were constrained by the Government per child budget allocation of GHS 0.40 (USD $0.26) per meal. Prices were compiled from two of Ghana’s major markets including Tamale in the north and Accra in the south. Descriptive statistics were used to analyze regional and seasonal variations with respect to energy, protein, fat, vitamin A and iron content. Adequacy was set at 30% of daily requirements for the relevant age group. The combined mean nutritional values of meals, using the mean yearly price of ingredients in each market, were as follows: energy – 654 kcal, protein - 13g, fat – 24g, iron – 4mg and vitamin A – 19mcg. The corresponding mean weight of the raw ingredients used to prepare a meal was 208g. The findings suggest that the majority of meals provided adequate amounts of protein and additionally in the North, most meals also had sufficient calories. However, meals were found to contain insufficient amounts of vitamin A and iron. Seasonal variations in the nutritional value of meals were not identified. This analysis shows that the current per child per day budget allocation is likely sufficient to meet some, but not all, of the nutritional adequacy targets for the programme. In the short term, there are opportunities to optimize the nutritional content of school meals in Ghana, including the use of fortification, although in the medium term, fostering healthy eating habits and consuming diets composed of nutrient rich varieties will see more enduring results. Strengthening both the meal planning and the monitoring of the school meal service provision could enhance programme implementation.Keywords: School meals, health, nutrition, meal quality, nutrient content, costs, evaluation

Refractive index variation in a free-standing diamond thin film induced by irradiation with fully transmitted high-energy protons

Ion irradiation is a widely employed tool to fabricate diamond micro- and nano-structures for applications in integrated photonics and quantum optics. In this context, it is essential to accurately assess the effect of ion-induced damage on the variation of the refractive index of the material, both to control the side effects in the fabrication process and possibly finely tune such variations. Several partially contradictory accounts have been provided on the effect of the ion irradiation on the refractive index of single crystal diamond. These discrepancies may be attributable to the fact that in all cases the ions are implanted in the bulk of the material, thus inducing a series of concurrent effects (volume expansion, stress, doping, etc.). Here we report the systematic characterization of the refractive index variations occurring in a 38 µm thin artificial diamond sample upon irradiation with high-energy (3 MeV and 5 MeV) protons. In this configuration the ions are fully transmitted through the sample, while inducing an almost uniform damage profile with depth. Therefore, our findings conclusively identify and accurately quantify the change in the material polarizability as a function of ion beam damage as the primary cause for the modification of its refractive index