1,721,050 research outputs found
Modellazione numerica del comportamento meccanico delle volte catalane
No full textIl presente lavoro riguarda la modellazione numerica del comportamento costitutivo delle cosiddette volte in foglio (le bóvedas tabicadas) che rappresentano una delle tecniche edilizie tradizionali catalane più diffusamente impiegate da alcuni tra i più grandi architetti spagnoli (primo fra tutti Gaudí) alla fine del XIX secolo [1-3]. Tali volte risultano fondamentalmente costituite da strati alternati di spessore in generale pressoché uguale di mattoni e di malta. Questa particolare caratteristica viene studiata in questo lavoro nel quale si vuole confrontare la modellazione del comportamento costitutivo considerando il materiale come ideale omogeneo con quella ottenuta modellando il materiale come stratificato. Tale studio consente di valutare in modo più aderente alla realtà la capacità portante delle volte catalane, il ruolo svolto dai diversi strati di malta e, ai fini dell’eventuale riabilitazione strutturale, l’incremento della capacità portante della stessa struttura rinforzata aggiungendo un numero opportuno di strati dello stesso materiale.
La caratterizzazione fisico-chimico-petrografica dei materiali viene effettuata prelevando opportuni campioni costituenti una struttura reale, mentre quella meccanica degli elementi strutturali viene effettuata attraverso prove di compressione centrata, flessione e presso flessione su elementi prelevati da strutture reali e rappresentativi di pannelli murari. Ancora, le caratteristiche meccaniche dei mattoni sono ottenute da prove di compressione e di flessione su provini estratti da elementi reali, mentre quelle della malta sono ottenute ai sensi delle vigenti normative in materia.
Una volta determinato il comportamento costitutivo dei materiali le prove sperimentali vengono riprodotte utilizzando il programma agli elementi finiti ADINA 8.6.1 modellando il materiale sia come omogeneo che come stratificato con i parametri meccanici ottenuti in precedenza. Le modellazioni ottenute vengono implementate per effettuare analisi computazionali di volte reali sulle quali sono state preventivamente effettuate delle prove di carico. Il confronto tra i risultati ottenuti consente di valutare il ruolo svolto dagli strati di malta e la loro influenza sul comportamento complessivo del materiale
A short introduction to pharmacokinetics
No full textPhamacokinetics is proposed to study the absorption, the distribution, the biotransformations and the elimination of drugs in man and animals. A single kinetic profile may be well summarized by Cmax, Tmax, t1/2 and AUC and, having more than one profile, 8 parameters at least, the mean and standard deviation of these parameters, may well summarize the drug kinetics in the whole population. A more carefull description of the data can be obtained interpolating and extrapolating the drug concentrations with some mathematical functions. These functions may be used to reduce all the data in a small set of parameters, or to verify if the hypotheses incorporated in the functions are confirmed by the observations. In the first case, we can say that the task is to get a simulation of the data, in the second to get a model. The functions used to interpolate and reduce the pharmacokinetic data are the multiexponential functions and the reference models are the compartmental models whose solutions are just the multiexponential functions. Using models, new meaningfull pharmacokinetic parameters may be defined which can be used to find relationships between the drug kinetic profile and the physiological process which drive the drug absorption, distribution and elimination. For example, compartmental models allow to define easily the clearance which is dependent on the drug elimination process, or the volume of distribution which depends on the drug distribution in the tissues. Models provide also an easy way to get an estimate of drug absorption after extravasculare drug administration (bioavailability). Model building is a complex multistep process where, experiment by experiment and simulation by simulation, new hypothesis are proven and disproven through a continuous interaction between the experimenter and the computer
Tecnologie e materiali innovativi per il restauro strutturale di edifici in c.a. di interesse storico – il teatro Finocchiaro a Palermo
No full textLa premessa fondamentale per la redazione di un progetto di restauro è la conoscenza del fabbricato, oggetto di intervento, delle sue evoluzioni nel tempo, dei materiali e delle tecnologie impiegate durante la sua realizzazione. Soltanto l’approfondimento di questa fase preliminare salvaguarda il progettista dal commettere errori e valutazioni sbagliate circa i materiali e le tecnologie da impiegare nel rapporto di compatibilità con l’esistente che si va a modificare, spesso integrare, comunque alterare. Per il teatro Finocchiaro a Palermo si è resa necessaria un’attenta e minuziosa indagine preliminare, culminata nel rilievo geometrico della fabbrica, con particolare attenzione alla valutazione della struttura portante mista in muratura e calcestruzzo armato
Renin–angiotensin system at the crossroad of hypertension and hypercholesterolemia
No full textAim The aim of this study is to discuss the reliable scientific evidence of an interactive link between hypertension and hypercholesterolemia considering the metabolic pathways and the pathogenetic mechanisms connecting the two risk factors. Data synthesis Hypertension and hypercholesterolemia are highly prevalent in the general population and their coexistence in the same subjects additively increases the risk of cardiovascular disease. Probably, hypercholesterolemia is also a risk factor for the development of hypertension. On the other side, it is also possible that lipid-lowering treatment could improve blood pressure control. Although the mechanisms of interaction between these two risk factors have not been completely elucidated thus far, there is rapidly growing evidence that the involvement of the renin–angiotensin system (RAS) can be considered as the common link between hypertension and hypercholesterolemia. In particular, hypercholesterolemia seems to promote the upregulation of type 1 angiotensin II (AT1) receptor genes because of an increase in the stability of mRNA followed by structural overexpression of vascular AT1 receptors for angiotensin II. The treatment of both risk factors greatly improves individual risk profile, especially when statins and RAS blockers are used together. Conclusions Hypertension and hypercholesterolemia are highly coprevalent and strongly related from a pathophysiological point of view. The RAS could be the main mediator of this link
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Moulds isolated from Istrian dried ham at the pre-ripening level
No full textThe aim of this study is to define the mould strains growing on the surface during the pre-ripening and the ripening phases of Istrian ham, and their toxic potential. The mould microflora was predominantly represented by five genera, which were isolated on the ham surfaces of three different producers investigated. The identified species were similar in the both tested periods, demonstrating that the contamination came mainly from the air and the ripening chambers (seasoning rooms), rather than the raw meat. Eurotium spp., Aspergillus spp. and Penicillium spp. were the main strains isolated. The presence and growth of the different strains depended on the temperature of ripening and the relative humidity in the ripening chambers, since the hams were home made products and not matured in controlled conditions. The toxic potential of isolated strains was also investigated. None of the tested moulds can produce mycotoxins and for this reason the Istrian hams do not represent a health hazard. © 2004 Elsevier B.V. All rights reserved
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