The gluon contribution to the polarized structure function g2g_2

We compute the structure function $g_2$ for a gluon target in perturbative QCD at order \as. We show that its first moment vanishes, as predicted by the Burkhardt-Cottingham sum rule.Comment: 9 pages Latex, uses epsfig.sty, 1 eps figure include

Comparison of two DEM strategies for modelling cortical meshes

This work deals with the particle-based modelling of cortical wire meshes. Such meshes are being used in many engineering applications but their modelling is particularly complex because of the common large displacement serviceability conditions, the chance of localized failures, and the intrinsic geometrical and mechanical anisotropies. The discrete element method has proved to be an excellent numerical tool for the investigation of such structures. Here, two modelling strategies are compared using a wire-node description and a wire-cylinder description: in the first the wire mesh is described by a collection of spheres at nodes linked by long-range interaction forces, in the second the wires are represented by means of interconnected cylinders. The force-displacement constitutive model of the interactions is calibrated based on specific tensile tests. The comparison is performed on results of tensile tests and punch tests on a reference mesh panel

STUDIO DI TECNOLOGIE DI AMPLIFICAZIONE E GENOTIPIZZAZIONE DEL GENOMA SU CAMPIONI DI DNA PROVENIENTI DA SANGUE E DA CELLULE DELLA BOCCA PER APPLICAZIONI IN AMBITO EPIDEMIOLOGICO

In epidemiological studies the amount of biological material available is a limiting factor. Many studies use DNA as biological sample obtained by venipuncture, but this collection method is invasive especially if donors are children and the elderly. The use of mouth cells can be an alternative source, although you get DNA of poor quality and quantity. To increase the amount of DNA extracted from buccal cells, you can use the "Whole Genome Amplification\u201d. The aim of my PhD project was to develop a method to extract DNA from buccal cells and to study amplification technologies and subsequent genotyping of DNA extracted from blood and buccal cells. The accuracy of WGA was evaluated with different techniques of molecular biology and genotyping: direct sequencing, allelic discrimination assays, microsatellite genotyping and \u201dgenome wide analysis\u201d. Our analysis showed that the WGA can be used to increase the amount of starting biological material, however, it has some limitations, the fact that direct sequencing and analysis with microsatellites in some cases, may cause a loss of 'genetic information\u2019. According to the data found using DNA from buccal cells and WGA, we have genotyped GSTP1 gene polymorphism Ile105/Val105 about 103 people in the Milan area through Real Time. The study of allele frequencies of this polymorphism in the GSTP1 gene is part of a project aiming to determine whether in patients with respiratory diseases there is an interaction between individual genetic predisposition and exposure to a common external agent coming from urban pollution. The genotypic frequencies obtained in our population were not significantly different from those of Tuscany population genotyped for the HapMap project, so our samples will be used as reference for future studies. Furthermore, we showed that both buccal cells and the WGA can be used in epidemiological analysis for genotyping through Real Time PCR. WGA may be a useful way to increase the amount of DNA; DNA extracted from buccal cells can be a valuable resource for genetic studies

Federico Cesi's Mycological Codex and its copies

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Who benefits from reducing the cost of formality? Quantile regression discontinuity analysis

This chapter studies the effect of increasing formality via tax reduction and simplification schemes on micro-firm performance. We develop a simple theoretical model that yields two intuitive results. First, low- and high-ability entrepreneurs are unlikely to be affected by a tax reduction and therefore, the reduction has an impact only on a segment of the microfirm population. Second, the benefits to such reduction, as measured by profits and revenues, are increasing in the entrepreneur's ability. Then, we estimate the effect of formality on the entire conditional distribution (quantiles) of revenues using the 1996 Brazilian SIMPLES program and a rich survey of formal and informal micro-firms. The econometric approach compares eligible and non-eligible firms, born before and after SIMPLES in a local interval about the introduction of SIMPLES. We develop an estimator that combines both quantile regression and the regression discontinuity design. The econometric results corroborate the positive effect of formality on micro-firms' performance and produce a clear characterization of who benefits from these programs

Continuous flow analysis method for determination of soluble iron and aluminium in ice cores

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Self-Perceived Loneliness and Depression During the COVID-19 Pandemic: a Two-Wave Replication Study

COVID-19 studies to date have documented some of the initial health consequences of lockdown restrictions adopted by many countries. Combining a data-driven machine learning paradigm and a statistical analysis approach, our previous paper documented a U-shape pattern in levels of self-perceived loneliness in both the UK and Greek populations during the first lockdown (17 April to 17 July 2020). The current paper aimed to test the robustness of these results. Specifically, we tested a) for the dependence of the chosen model by adopting a new one - namely, support vector regressor (SVR). Furthermore, b) whether the patterns of self-perceived loneliness found in data from the first UK national lockdown could be generalizable to the second wave of the UK lockdown (17 October 2020 to 31 January 2021). The first part of the study involved training an SVR model on the 75% of the UK dataset from wave 1 (n total = 435). This SVR model was then tested on the remaining 25% of data (MSE training = 2.04; MSE test = 2.29), which resulted in depressive symptoms to be the most important variable - followed by self-perceived loneliness. Statistical analysis of depressive symptoms by week of lockdown resulted in a significant U-shape pattern between week 3 to 7 of lockdown. In the second part of the study, data from wave 2 of the UK lockdown (n = 263) was used to conduct a graphical and statistical inspection of the week-by-week distribution of scores regarding self-perceived loneliness. Despite a graphical U-shaped pattern between week 3 and 9 of lockdown, levels of loneliness were not between weeks of lockdown. Consistent with past studies, study findings suggest that self-perceived loneliness and depressive symptoms may be two of the most relevant symptoms to address when imposing lockdown restrictions