The geochemical behavior of metalloids and their effect on the highly siderophile elements during the crystallization of a magmatic sulfide liquid in relation to the formation of Ni-Cu-PGE magmatic sulfide deposits

The highly siderophile elements (HSE), which include Re, Au and the platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt) are of scientific and economic interest because they are tracers of geological processes (e.g., planetary differentiation) or have industrial or investment value. In most ore deposits, HSE are usually mined as by-products of Ni-Cu mineralization, such as those of the Sudbury district (Canada). Although at high temperature HSE are expected to be in lattice of sulfides they are usually found as discrete phases or platinum-group minerals (PGM). Many of PGM have metalloids (As, Se, Sb, Te and Bi) as essential constituents but, despite this relationship, the role of metalloids on HSE mineralization is still unclear. This dissertation documents the results of three experimental studies undertaken to investigate the effect of metalloids on the geochemistry of HSE. The first study examined whether the metalloids can mobilize HSE in an anhydrous environment. The results show that metalloids do not transport the HSE but also that Au, Pd and Pt can be efficiently fractionated from the other HSE and transported away from a sulfide assemblage through a relatively low-porosity, low-permeability medium in absence of hydrothermal fluids. The second study investigated the solubility of metalloids in monosulfide solid solution (mss) and intermediate solid solution (iss), to asses the conditions required for the formation of immiscible metalloid liquids and their effect on HSE partitioning. The results show that the metalloids form two separate phases, one that is As-rich and strongly sequestered Pt from the sulfides and another that is Bi-Te rich and affected mostly Pd and Au. The results also show that the other HSE (Ru, Rh, Re, Os, Ir) are largely unaffected by the presence of metalloids. In addition the results show that mss can dissolve significant amounts of metalloids (hundreds of ppm) before metalloid V saturation can occur. The third study constrained the geochemical behavior of metalloids and HSE in a pyrite-bearing sulfide system. The results show that Co-Ni-rich and HSE bearing pyrite can form during cooling of a sulfide melt and also that the HSE partition roughly equally between mss and pyrite, whereas Pd that partitions preferentially into mss and Au partitions preferentially into iss. Moreover, pyrite showed compositional zonation of many elements similar to that documented in natural pyrite samples that are also Co-rich and HSE-bearing. Thus, identification of such pyrite in natural assemblages is consistent with a magmatic origin.Doctor of Philosophy (Ph.D.) in Mineral Deposits and Precambrian Geolog

Libertà del volere e concetto di persona nella filosofia dello spirito di Hegel

Hegel’s definition of ‘free will’ and ‘person’ gets over a phenomenological or psychological definition of these concepts. My essay explains how Hegel justifies the placing of his theory of free will in a philosophy of Mind analyzing the concept of ‘recognition’ in the Phenomenology as a section of the Encyclopedia of Philosophical Sciences as well as the main steps of The practical Spirit, the second part of the section Psychology. With regard to this last science my essay clarifies the essential differences between freedom of the will and freedom of choice. These differences only explain how the free will could develop as objective Spirit in the third science involved by Hegel towards a proper definition of freedom, i.e. the philosophy of Right. In the philosophy of Right as a part of Hegel’s System of philosophical sciences the free will finds its own adequate reality and the concept of a person can be explained without the mistakes caused by a phenomenological or psychological approach to it. Against some interpretations which identify Hegel’s definition of free will with communitarian practices, the final part of my essay focuses on the importance of the concept of a person to explain the general structure of the philosophy of Right

Significado formativo e participação democrática: uma pesquisa sobre o ensino da história e da literatura

The research presented here aims to be part of debate of the importance of the humanities and to offer its contribution from an educational point of view. The matter in question is the teaching of the humanities, in particular history and literature though dealt with in an unusual and exploratory way, albeit with a clear purpose: listening to students to find out how and to what extent their voice and intimate involvement in the topic of the study can contribute to a greater understanding of the teaching-learning process and to an improvement in terms of effectiveness of teaching practices, in reference specifically to the two humanistic subjects under scrutiny

Educational level and 30-day outcomes after hospitalization for acute myocardial infarction in Italy

Background There is a growing interest in the factors that influence short-term mortality and readmission after hospitalization for acute myocardial infarction (AMI) since such outcomes are commonly considered as hospital performance measures. Socioeconomic status (SES) is one of the factors contributing to healthcare outcomes after hospitalization for AMI. However, no study has been published on education and 30-day readmission in Europe. The objective of this study is to examine the association between educational level and 30-day mortality and readmission among patients hospitalized for AMI in Tuscany (Italy). Methods A retrospective cohort study using data from hospital discharge records was conducted. The analysis included all patients discharged with a principal diagnosis of AMI between January 1, 2011, and November 30, 2014, from all hospitals in Tuscany. Educational level was categorized as low (no middle school diploma), mid (middle school diploma) and high (high school diploma or more). Three multilevel models were developed, sequentially controlling for patient-level socio-demographic and clinical variables and hospital-level variables. Patients were stratified by age (≤75 and >75 years). Results Mortality analysis included 23,402 patients, readmission analysis included 22,181 patients. In both unadjusted and full-adjusted models, patients with a high education had lower odds of 30-day mortality compared to those patients with low education (OR age ≤ 75 years 0.67, 95% CI:0.47–0.94; OR age > 75 years 0.72, 95% CI:0.54–0.95). With regard to 30-day readmission, only patients aged over 75 years with a high education had lower odds of short-term readmission compared to those patients with low education (OR age > 75 0.73, 95% CI:0.58–0.93). Conclusions Among patients hospitalized in Tuscany for AMI, low levels of education were associated with increased odds of 30-day mortality for both age groups and increased odds of 30-day readmission only for patients aged over 75 years. Our findings suggest that the educational component should not be underestimated in order to improve short-term outcomes, which are considered as performance measures at the hospital level. Hospital managers might consider strategies that are sensitive to patients with low SES, such as providing post-hospitalization support to less-educated patients and promoting a healthier lifestyle, to improve both health equity and performance outcomes

Economic sustainability of biogas production from animal manure: a regional circular economy model

Purpose: This paper aims to understand the implementation of a circular economic business where animal manure is used to produce biogas and alternative fertilizer in a regional network of manure suppliers and biogas producers and to reveal the impacts of five variables (manure quantity, transportation distance, manure dry content, manure price and manure discharge price) on the economic sustainability of manure-based biogas supply chains. Design/methodology/approach: An enterprise input-output approach is used to model physical and monetary flows of the manure-based biogas supply chain. Computational experiments are performed on all variables to identify under which conditions the cooperation is beneficial for all actors. Findings: The cooperation is profitable for a large-scale farm (>20,000 t/year) if biogas producer (b) pays farmer (f) to receive its manure (5 €/t) or if f sells manure for free and manure disposal costs are >10 €/t. Cooperation is always profitable for b if f pays b to supply its manure (5€/t). If b receives manure for free, benefits are always positive if b is a medium-large-scale plant (>20,000 t/year). For a small-scale plant, benefits are positive if manure dry content (MDC) is ≥12 per cent and transportation distance is ≤10 km. Originality/value: The paper adds value to the biogas production research, as it makes holistic analysis of five variables which might change under different policy and geographical conditions. The investors in biogas production, suppliers and transportation companies can find correspondence to empirical findings for their own site-specific cases