Phase equilibrium constraints on the production and storage of peralkaline silicic magmas: insights from Kenya and Pantelleria.

The origin of peralkaline silicic rocks is still obscure and stands perhaps as one of the last major unsettled issues in classic igneous petrology. The debate goes back to the end of the 18th century and despite intensive petrological, geochemical and laboratory efforts the consensus has yet to emerge as to which mechanisms produce peralkaline derivatives. Bowen (1937) first proposed that the shift from metaluminous to peralkaline field was due to extensive fractionation of calcic plagioclase. Perhaps the best illustration of such an hypothesis is provided by the Boina rock series in the Ethiopian rift studied by Barberi et al. (1975). However, such an hypothesis still awaits experimental confirmation. A different view has been expressed for the origin of peralkaline rhyolites erupted in the central part of the Kenya Rift Valley. There, a partial melting of crustal protoliths has been advocated on the basis of geochemical arguments (Macdonald et al., 1987). The origin of peralkaline rocks at Pantelleria, the type locality of peralkaline rhyolites, is also a matter of debate. Mahood et al (1990) have proposed an origin via partial melting of Fe-rich differentiates of transitional basalts, whilst Civetta et al. (1998) have argued that pantellerites could be produced via extensive fractionation of their putative parent basalts. The diversity of opinions reflects in part that, presumably, there is not only one mechanism at work. But it is also due to the fact that most experimental studies devoted to the clarification of this problem have failed in producing decisive arguments during more than one century of intense debate

Oltre il Segno/OltreMare

La realizzazione di un volume contenente le incisioni scelte all’interno della Scuola di Grafica d’Arte dell’Accademia di Belle Arti di Palermo, coordinata dai Proff. Giovanni D’Alessandro e Riccardo Mazzarino rappresenta motivo di orgoglio e di soddisfazione per la nostra Istituzione che costruisce i percorsi didattici dei propri corsi a partire dall’esperienza laboratoriale. L’incisione grafica è tra le tecniche artistiche più antiche ma nel contempo più contemporanee. La gestualità intrinseca al segno, che si manifesta nella carta, svela universi della visione inaspettati.(Mario Zito - Direttore dell’Accademia di Belle Arti di Palermo) Il segno è il risultato di un gesto a volte deciso, a volte contorto, a volte leggero, i cui risultati spesso sono inattesi e sorprendenti. Il volume contiene esemplari di incisioni fortemente caratterizzanti della scuola di Grafica d’Arte che vanta all’interno del proprio corso di studi docenti-artisti che consapevoli della ricchezza del loro bagaglio esperienziale offrono agli studenti gli strumenti necessari per far sì che l’arte del saper fare artigianale, si trasformi in mera poetica artistica

La piccola impresa cinematografica in Italia

Analisi dell'industria cinematografica italiana specializzata nella produzione di tecnologi

Phase equilibrium constraints on the production and storage of peralkaline silicic magmas: insights from Kenya and Pantelleria.

The origin of peralkaline silicic rocks is still obscure and stands perhaps as one of the last major unsettled issues in classic igneous petrology. The debate goes back to the end of the 18th century and despite intensive petrological, geochemical and laboratory efforts the consensus has yet to emerge as to which mechanisms produce peralkaline derivatives. Bowen (1937) first proposed that the shift from metaluminous to peralkaline field was due to extensive fractionation of calcic plagioclase. Perhaps the best illustration of such an hypothesis is provided by the Boina rock series in the Ethiopian rift studied by Barberi et al. (1975). However, such an hypothesis still awaits experimental confirmation. A different view has been expressed for the origin of peralkaline rhyolites erupted in the central part of the Kenya Rift Valley. There, a partial melting of crustal protoliths has been advocated on the basis of geochemical arguments (Macdonald et al., 1987). The origin of peralkaline rocks at Pantelleria, the type locality of peralkaline rhyolites, is also a matter of debate. Mahood et al (1990) have proposed an origin via partial melting of Fe-rich differentiates of transitional basalts, whilst Civetta et al. (1998) have argued that pantellerites could be produced via extensive fractionation of their putative parent basalts. The diversity of opinions reflects in part that, presumably, there is not only one mechanism at work. But it is also due to the fact that most experimental studies devoted to the clarification of this problem have failed in producing decisive arguments during more than one century of intense debate

Suspense cinematografica e creazione dell'attenzione: analisi comparata di due sequenze hitchcockiane

Il saggio indaga il rapporto tra testo cinematografico e spettatore tenendo conto di due meccanismi: quello semiotico del film e quello psicologico di chi lo guarda

Phase Equilibrium Constraints on Pre-eruptive Conditions of Recent Felsic Explosive Volcanism at Pantelleria Island, Italy

We present experimental phase equilibria carried out on a pantelleritic bulk-rock composition with a peralkalinity index [PI molar (Na2O þK2O)/Al2O3] 1·4, which is representative of the most energetic pumice fall eruption of the resurgent post-caldera volcanism on Pantelleria island. For the explored conditions (P 25^ 150 MPa; T 680^8008C; H2Omelt up to 6 wt %; fO2 NNO, where NNO is nickel^nickel oxide buffer) clinopyroxene is the liquidus phase followed by alkali feldspar and then quartz. The crystallization of amphibole is limited to temperatures below 7008C. Aenigmatite crystallizes near the liquidus for P 100 MPa. When clinopyroxene is the sole liquidus phase, the coexisting melt is characterized by a decrease in peralkalinity index to 1·2, if compared with the starting material, approaching comendite composition. In contrast, when alkali feldspar joins the liquidus phase assemblage, residual melts become extremely peralkaline (PI 3·2), with Fe

Screening and Management of Coronary Artery Disease in Kidney Transplant Candidates

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD), especially in end-stage renal disease (ESRD) patients and during the first year after transplantation. For these reasons, and due to the shortage of organs available for transplant, it is of utmost importance to identify patients with a good life expectancy after transplant and minimize the transplant peri-operative risk. Various conditions, such as severe pulmonary diseases, recent myocardial infarction or stroke, and severe aorto-iliac atherosclerosis, need to be ruled out before adding a patient to the transplant waiting list. The effectiveness of systematic coronary artery disease (CAD) treatment before kidney transplant is still debated, and there is no universal screening protocol, not to mention that a nontailored screening could lead to unnecessary invasive procedures and delay or exclude some patients from transplantation. Despite the different clinical guidelines on CAD screening in kidney transplant candidates that exist, up to today, there is no worldwide universal protocol. This review summarizes the key points of cardiovascular risk assessment in renal transplant candidates and faces the role of noninvasive cardiovascular imaging tools and the impact of coronary revascularization versus best medical therapy before kidney transplant on a patient’s cardiovascular outcome

Coronary Arteries Aneurysms: A Case-Based Literature Review

Abstract: Coronary artery aneurysm (CAA) is an abnormal dilatation of a coronary artery segment; those coronary artery aneurysms that are very large in size are defined as giant. However, a standardized dimension cut-off to define giant CAAs is still missing. The reported prevalence of coronary aneurysms in the population who underwent coronary angiography ranges from 0.3% to 5%, and often CAAs are found in patient with aneurysms in other sites, such as the ascending or abdominal aorta. In half of the cases an atherosclerotic etiology could be recognized; often, CAA is found in the context of acute coronary syndrome. Seldomly, CAA is found at the autopsy of patients who died due to sudden cardiac death. Currently, very few data exist about CAA management and their prognostic relevance; moreover, CAA treatment is still not clearly codified, but rather case-based. Indeed, currently there are no published dedicated studies exploring the best medical therapy, i.e., with antiplatelets or anticoagulant agents rather than an interventional approach such as an endovascular or surgical technique. In this review, through two clinical cases, the current evidence regarding diagnostic tools and treatment options of CAAs will be described

Coronary artery fistulas: symptoms may not correlate to size. An emblematic case and literature review

Fistulous communication of coronary with pulmonary arteries in the adults is a common type of coronary artery fistula (CAF)1—3. In most reported cases, the fistula usually arises from the proximal left and/or right coronary arteries via the anterior conal branches that connect to the anterior wall of the main pulmonary artery. These anteriorly located abnormal communications are usually asymptomatic and are incidentally found during an angiography of the coronary arteries in 0.2—0.3% of the exams