Differenze emodinamiche dopo test da sforzo rettangolari di diversa intensità e durata

La risposta emodinamica all'esercizio dinamico è stata oggetto di numerosi studi scientifici. Poca attenzione è stata invece rivolta agli aggiustamenti cardiovascolari che si verificano quando si interrompe uno sforzo dinamico. Al cessare dell' esercizio, la frequenza cardiaca e la contrattilità miocardica subiscono un decremento repentino e vengono rilasciati in quantità i prodotti finali del metabolismo muscolare, come lattato, ioni idrogeno, adenosina, sostanze in grado di indurre vasodilatazione nei gruppi muscolari precedentemente attivati determinando una riduzione del precarico, post-carico cardiaco, contrattilità miocardica e una dilatazione delle arteriole periferiche, così da mantenere le resistenze vascolari periferiche a un basso livello. Inoltre, si verificano alterazioni della concentrazione ematica di elettroliti, diminuzione delle catecolamine circolanti e si verifica un ipertono vagale : tutti questi fenomeni possono avere un effetto significativo sullo stato emodinamico. In questo studio si voleva valutare in che misura l’eventuale effetto ipotensivo dovuto all’esercizio fosse legato all’intensità del carico lavorativo applicato ed alla sua durata. Il campione esaminato comprendeva 20 soggetti maschi attivi. I soggetti venivano sottoposti a quattro test in giornate diverse. La prova da sforzo preliminare consisteva in una prova da sforzo triangolare massimale eseguita al cicloergometro con un protocollo incrementale di 30 Watt al minuto. Il test si articolava in una prima fase della durata di 3 minuti nei quali venivano registrati i dati basali, in una seconda fase della durata di tre minuti in cui il soggetto compiva un riscaldamento al cicloergometro, che precedeva l’inizio dello sforzo, ad un carico di 20 W. Al termine della prova venivano calcolati il massimo carico lavorativo raggiunto (Wmax) ed il valore di soglia anaerobica (SA). Dopo la prova da sforzo preliminare il soggetto effettuava 3 esercizi rettangolari di diversa intensità in maniera randomizzata così strutturati: test 70% SA; test 130% SA, 130% Wmax : prove da sforzo rettangolari ad un carico lavorativo pari alla percentuale indicatain relazione ai valori di SA e Wmax ottenuti nella prova da sforzo preliminare. Tali test duravano dieci minuti o fino all'esaurimento del soggetto. Le prova erano precedute da tre minuti di riposo e da tre minuti di riscaldamento. Il recupero aveva una durata di 30 minuti. La PA veniva misurata ogni 5 minuti durante lo sforzo, ogni minuto nei primi 5 minuti di recupero e successivamente ogni 5 minuti fino alla conclusione del recupero. Dai risultati emerge come l'effetto ipotensivo sia stato più marcato nel recupero dall'intensità di carico lavorativo meno elevata, cioè dopo il test 70%SA. C'è da considerare che la più bassa intensità di sforzo permetteva di praticare un esercizio significativamente più lungo rispetto ai test 130%SA e 130%Wmax. È quindi verosimile che anche la durata dell'esercizio e non solo la sua intensità abbia avuto un ruolo fondamentale nel determinare l'ipotensione nel recupero evidenziata in questo studio. L’effetto ipotensivo più evidente si è manifestato nelle prove a più bassa intensità ma con carico lavorativo totale più elevato. I dati supportano la tendenza a considerare non tanto l’intensità e la durata dell’esercizio in modo isolato, quanto piuttosto il carico lavorativo totale (intensità x durata). L'effetto ipotensivo registrato nello studio è da ascriversi soprattutto ad una persistente vasodilatazione susseguente allo sforzo. Infatti, nel recupero dal test 70%SA, le RVP si mantenevano basse rispetto ai valori di riposo. Tale dato potrebbe avere un grande valore clinico nella prescrizione dell'attività fisica più idonea nei soggetti ipertesi,che potrebbero beneficiare di un eventuale effetto ipotensivo successivo all'attività praticata. Pertanto in futuro bisognerà estendere lo studio ai soggetti ipertesi. La conferma di tale risultato in questi soggetti permetterebbe di scegliere correttamente l'intensità e la durata del carico lavorativo, in modo da calibrare lo sforzo al grado di patologia del soggetto.

Sostanzialismo e relazionalismo dello spaziotempo alla luce della relatività generale

Until recently the debate on the ontology of spacetime had only a philosophical significance, since, from a physical point of view, General Relativity has been made "immune" to the consequences of the "Hole Argument" simply by reducing the subject to the assertion that solutions of Einstein equations which are mathematically different and related by an active diffeomorfism are physically equivalent. From a technical point of view, the natural reading of the consequences of the "Hole Argument” has always been to go further and say that the mathematical representation of spacetime in General Relativity inevitably contains a “superfluous structure” brought to light by the gauge freedom of the theory. This position of apparent split between the philosophical outcome and the physical one has been corrected thanks to a meticulous and complicated formal analysis of the theory in a fundamental and recent (2006) work by Luca Lusanna and Massimo Pauri entitled “Explaining Leibniz equivalence as difference of non-inertial appearances: dis-solution of the Hole Argument and physical individuation of point-events”. The main result of this article is that of having shown how, from a physical point of view, point-events of Einstein empty spacetime, in a particular class of models considered by them, are literally identifiable with the autonomous degrees of freedom of the gravitational field (the Dirac observables, DO). In the light of philosophical considerations based on realism assumptions of the theories and entities, the two authors then conclude by saying that spacetime point-events have a degree of "weak objectivity", since they, depending on a NIF (non-inertial frame), unlike the points of the homogeneous newtonian space, are plunged in a rich and complex non-local holistic structure provided by the “ontic part” of the metric field. Therefore according to the complex structure of spacetime that General Relativity highlights and within the declared limits of a methodology based on a Galilean scientific representation, we can certainly assert that spacetime has got "elements of reality", but the inevitably relational elements that are in the physical detection of point-events in the vacuum of matter (highlighted by the “ontic part” of the metric field, the DO) are closely dependent on the choice of the global spatiotemporal laboratory where the dynamics is expressed (NIF). According to the two authors, a peculiar kind of structuralism takes shape: the point structuralism, with common features both of the absolutist and substantival tradition and of the relationalist one. The intention of this thesis is that of proposing a method of approaching the problem that is, at least at the beginning, independent from the previous ones, that is to propose an approach based on the possibility of describing the gravitational field at three distinct levels. In other words, keeping the results achieved by the work of Lusanna and Pauri in mind and following their underlying philosophical assumptions, we intend to partially converge to their structuralist approach, but starting from what we believe is the "foundational peculiarity" of General Relativity, which is that characteristic inherent in the elements that constitute its formal structure: its essentially geometric nature as a theory considered regardless of the empirical necessity of the measure theory. Observing the theory of General Relativity from this perspective, we can find a "triple modality" for describing the gravitational field that is essentially based on a geometric interpretation of the spacetime structure. The gravitational field is now "visible" no longer in terms of its autonomous degrees of freedom (the DO), which, in fact, do not have a tensorial and, therefore, nor geometric nature, but it is analyzable through three levels: a first one, called the potential level (which the theory identifies with the components of the metric tensor), a second one, known as the connections level (which in the theory determine the forces acting on the mass and, as such, offer a level of description related to the one that the newtonian gravitation provides in terms of components of the gravitational field) and, finally, a third level, that of the Riemann tensor, which is peculiar to General Relativity only. Focusing from the beginning on what is called the "third level" seems to present immediately a first advantage: to lead directly to a description of spacetime properties in terms of gauge-invariant quantites, which allows to "short circuit" the long path that, in the treatises analyzed, leads to identify the "ontic part” of the metric field. It is then shown how to this last level it is possible to establish a “primitive level of objectivity” of spacetime in terms of the effects that matter exercises in extended domains of spacetime geometrical structure; these effects are described by invariants of the Riemann tensor, in particular of its irreducible part: the Weyl tensor. The convergence towards the affirmation by Lusanna and Pauri that the existence of a holistic, non-local and relational structure from which the properties quantitatively identified of point-events depend (in addition to their own intrinsic detection), even if it is obtained from different considerations, is realized, in our opinion, in the assignment of a crucial role to the degree of curvature of spacetime that is defined by the Weyl tensor even in the case of empty spacetimes (as in the analysis conducted by Lusanna and Pauri). In the end, matter, regarded as the physical counterpart of spacetime curvature, whose expression is the Weyl tensor, changes the value of this tensor even in spacetimes without matter. In this way, going back to the approach of Lusanna and Pauri, it affects the DOs evolution and, consequently, the physical identification of point-events (as our authors claim). In conclusion, we think that it is possible to see the holistic, relational, and non-local structure of spacetime also through the "behavior" of the Weyl tensor in terms of the Riemann tensor. This "behavior" that leads to geometrical effects of curvature is characterized from the beginning by the fact that it concerns extensive domains of the manifold (although it should be pointed out that the values of the Weyl tensor change from point to point) by virtue of the fact that the action of matter elsewhere indefinitely acts. Finally, we think that the characteristic relationality of spacetime structure should be identified in this "primitive level of organization" of spacetime.

Algorithms for network design and routing problems

In this thesis we study three combinatorial optimization problems belonging to the classes of Network Design and Vehicle Routing problems that are strongly linked in the context of the design and management of transportation networks: the Non-Bifurcated Capacitated Network Design Problem (NBP), the Period Vehicle Routing Problem (PVRP) and the Pickup and Delivery Problem with Time Windows (PDPTW). These problems are NP-hard and contain as special cases some well known difficult problems such as the Traveling Salesman Problem and the Steiner Tree Problem. Moreover, they model the core structure of many practical problems arising in logistics and telecommunications. The NBP is the problem of designing the optimum network to satisfy a given set of traffic demands. Given a set of nodes, a set of potential links and a set of point-to-point demands called commodities, the objective is to select the links to install and dimension their capacities so that all the demands can be routed between their respective endpoints, and the sum of link fixed costs and commodity routing costs is minimized. The problem is called non- bifurcated because the solution network must allow each demand to follow a single path, i.e., the flow of each demand cannot be splitted. Although this is the case in many real applications, the NBP has received significantly less attention in the literature than other capacitated network design problems that allow bifurcation. We describe an exact algorithm for the NBP that is based on solving by an integer programming solver a formulation of the problem strengthened by simple valid inequalities and four new heuristic algorithms. One of these heuristics is an adaptive memory metaheuristic, based on partial enumeration, that could be applied to a wider class of structured combinatorial optimization problems. In the PVRP a fleet of vehicles of identical capacity must be used to service a set of customers over a planning period of several days. Each customer specifies a service frequency, a set of allowable day-combinations and a quantity of product that the customer must receive every time he is visited. For example, a customer may require to be visited twice during a 5-day period imposing that these visits take place on Monday-Thursday or Monday-Friday or Tuesday-Friday. The problem consists in simultaneously assigning a day- combination to each customer and in designing the vehicle routes for each day so that each customer is visited the required number of times, the number of routes on each day does not exceed the number of vehicles available, and the total cost of the routes over the period is minimized. We also consider a tactical variant of this problem, called Tactical Planning Vehicle Routing Problem, where customers require to be visited on a specific day of the period but a penalty cost, called service cost, can be paid to postpone the visit to a later day than that required. At our knowledge all the algorithms proposed in the literature for the PVRP are heuristics. In this thesis we present for the first time an exact algorithm for the PVRP that is based on different relaxations of a set partitioning-like formulation. The effectiveness of the proposed algorithm is tested on a set of instances from the literature and on a new set of instances. Finally, the PDPTW is to service a set of transportation requests using a fleet of identical vehicles of limited capacity located at a central depot. Each request specifies a pickup location and a delivery location and requires that a given quantity of load is transported from the pickup location to the delivery location. Moreover, each location can be visited only within an associated time window. Each vehicle can perform at most one route and the problem is to satisfy all the requests using the available vehicles so that each request is serviced by a single vehicle, the load on each vehicle does not exceed the capacity, and all locations are visited according to their time window. We formulate the PDPTW as a set partitioning-like problem with additional cuts and we propose an exact algorithm based on different relaxations of the mathematical formulation and a branch-and-cut-and-price algorithm. The new algorithm is tested on two classes of problems from the literature and compared with a recent branch-and-cut-and-price algorithm from the literature.

Biomasse e loro quantificazione economica per un efficiente uso dell'energia

Biomasses and their possible use as energy resource are of great interest today, and the general problem of energy resources as well. In the present study the key questions of the convenience, from both energy and economy standpoints, have been addressed without any bias: the problem has been handled starting from “philosophical” bases disregarding any pre-settled ideology or political trend, but simply using mathematical approaches as logical tools for defining balances in a right way. In this context quantitative indexes such as LCA and EROEI have been widely used, together with multicriteria methods (such as ELECTRE) as decision supporting tools. This approach permits to remove mythologies, such as the unrealistic concept of clean energy, or the strange idea of biomasses as a magic to solve every thing in the field of the energy. As a consequence the present study aims to find any relevant aspect potentially useful for the society, looking at any possible source of energy without prejudices but without unrealistic expectations too. For what concerns biomasses, we studied in great details four very different cases of study, in order to have a scenario as various as much we can. A relevant result is the need to use biomasses together with other more efficient sources, especially recovering by-products from silviculture activities: but attention should be paid to the transportation and environmental costs. Another relevant result is the very difficult possibility of reliable evaluation of dedicated cultures as sources for “biomasses for energy”: the problem has to be carefully evaluated case-by-case, because what seems useful in a context, becomes totally disruptive in another one. In any case the concept itself of convenience is not well defined at a level of macrosystem: it seems more appropriate to limit this very concept at a level of microsystem, considering that what sounds fine in a limited well defined microsystem may cause great damage in another slightly different, or even very similar, microsystem. This approach seems the right way to solve the controversy about the concept of convenience.

Ruolo dell'Infliximab nella terapia della colite ulcerosa moderato-severa

Background: Almost 10-15% of patients with active Ulcerative Colitis are refractory to conventional therapy. Infliximab is a treatment of proven efficacy in this group of patients. Aims: To evaluate the role of Inliximab in inducing and maintaining remission in patients with chronically active moderate-severe Ulcerative Colitis. Materials and methods: 53 patients were enrolled, 47 patients entered the study and were treated with a dose of 5 mg/kg. The remission was evaluated through endoscopy and clinical criteria. (Mayo Score). The primary endpoint were clinical and endoscopic remission in moderate-severe Ulcerative Colitis refractory to standard therapy, the secondary out point was the maintenance of remission in the long period. Results: 47 patients started the study, 43 completed the study, 4 dropped out for worsening disease or adverse events; 27 patients were treated with 3 infusions, 9 patients with 4 infusions, 7 patients with > o = 5 infusions. 34 /47 patients (72.3%) were responders 12 (25.5%) improved their symptoms, 22 ( 46.8%) were in remission after the treatment. Among the responders, 21/34 (61.8%) stopped the steroid therapy after 3 infusions, the others reduced the dose or maintained just topic therapy. 13/47 patients (27.7%) were non responders (p <0.001). After 3 months all 22 patients which had reached remission maintained low Mayo Score; 10/12 (83.3%) patients with clinical response maintained their low score, 2 relapsed . Conclusions: Infliximab is a valid therapy for the treatment of Ulcerative Colitis and can avoid surgery in selected patients.

Theoretical and Experimental Study of the Magnetic Separation of Pollutants from Wastewater

This Thesys reports the study of a HGMS (High GradientMagnetic Separation) process for the treatment of industrialwastewaters that considers an assisted chemical-physical pre-treatment for the removal of heavy metals through the bound by adsorption with added iron-oxide particulate matter (hematite). The considered filter, constituted by ferromagnetic stainless steel wool and permanent magnets, is studied with a new approach based on a statistical analysis that requires the study of the trajectories of the particles. Experimental activity on a laboratory device has been carried out in order to test the model.

L'istituto dell'incompatibilità nel pubblico impiego

Dopo aver brevemente ricostruito l’evoluzione dell’istituto dell’incompatibilità nel pubblico impiego, tra la sua introduzione nell’Ordinamento italiano nel 1908 e la sua attuale formulazione (attraverso le riforme del 1923 e del 1957), l’autore –contestando un’opinione diffusa nella letteratura giuslavoristica- esclude che l’art. 98 Cost. obblighi il legislatore ordinario ad imporre un dovere di esclusività al lavoratore dipendente dalle pubbliche amministrazioni. Successivamente si osserva come nel corso di più di un secolo la Dottrina, comunque poco interessata al tema, non abbia saputo giustificare in maniera unitaria e coerente la disciplina delle incompatibilità (se non ricorrendo ad argomentazioni di natura etica o sociale); diversamente la Giurisprudenza, soprattutto in epoca repubblicana, ha cercato di ricondurre la ratio dell’istituto alla specificità del rapporto lavorativo, riuscendo a giustificare le previsioni (e a individuarne i confini di applicazione) solo in relazione alla specialità del rapporto di lavoro pubblico. Nel secondo capitolo si evidenzia come, in occasione della riforma di fine XX secolo, la scelta di riservare alla legge la disciplina delle incompatibilità nel pubblico impiego non sia necessariamente in contrasto con la privatizzazione del lavoro pubblico. Si descrivono inoltre le linee generali dell’istituto, evidenziandone gli aspetti problematici (in particolare rapporto tra art. 53 del D.Lgvo 165/01 e l’art. 1 commi 57 e ss. della L. 662/96) e la collocazione nell’ambito complessivo della riforma di privatizzazione (con particolare attenzione al tema della natura degli atti). Nell’ultimo capitolo, si evidenziano le criticità della disciplina vigente, anche alla luce della discutibile interpretazione datane dalla Corte di Cassazione. In particolare si sottolinea come il sistema sanzionatorio non sia coerente con la contrattualizzazione del rapporto di lavoro e mantenga una forte connotazione pubblicistica. Si rileva quindi come le critiche all’istituto si possano sostanzialmente ricondurre al fatto che il legislatore, mantenendo in vita un istituto risalente e riconducibile a esigenze di varia natura, non ha individuato univocamente nè il fine ultimo delle norme nè quale sia il bene che si intende proteggere; in tal modo si è disegnato un sistema che vieta irragionevolmente le sole attività remunerative, implica una profonda differenziazione pubblico/privato, comporta un sacrificio significativo per il lavoratore pubblico. Dopo aver negato la possibilità di ricondurre l’istituto alle previsioni di cui all’art. 2105 c.c., l’autore, riflettendo sulle ragioni fondanti l’esistenza di tale ultima previsione e in considerazione del dato incontrovertibile che oggi l’ordinamento fonda sul contratto sia i rapporti di impiego pubblico sia quelli di impiego privato, giunge ad individuare un unitario principio secondo il quale è illecito lo svolgimento, da parte del lavoratore, di attività inconciliabili con gli interessi che costituiscono la giustificazione profonda dell’attività del datore di lavoro. Si tratterebbe, insomma, di “un generale principio di tutela dell’interesse pubblico al regolare svolgimento dell’attività del datore, che si concretizza in entrambi i casi nel sorgere di obbligazioni negative (di non fare/di astenersi) in capo al lavoratore, riferite alle attività concorrenziali e a quelle incompatibili”(Cap III, 3.3) rispettivamente nel privato e nel pubblico Alla luce della esposta conclusione, l’autore auspica che tutto il sistema delle incompatibilità venga ridisegnato in una prospettiva che tenga conto dell’esigenza di uniformare al massimo le regole che governano il lavoro, indipendentemente dalla soggettività (pubblica o privata) dei datori. Un simile obiettivo, in termini di coerenza ed efficacia, appare perseguibile a partire dal modello disegnato dall’art. 53 del D.Lgvo 165/01 in materia di incarichi autorizzabili.

La psicologia della Gestalt. Ricerche teoriche e sperimentali sulla percezione sonora e musicale (1890-1939)

The aim of the present work is a historical survey on Gestalt trends in psychological research between late 19th and the first half of 20th century with privileged reference to sound and musical perception by means of a reconsideration of experimental and theoretical literature. Ernst Mach and Christian von Ehrenfels gave rise to the debate about Gestaltqualität which notably grew thanks to the ‘Graz School’ (Alexius Meinong, Stephan Witasek, Anton Faist, Vittorio Benussi), where the object theory and the production theory of perception were worked out. Stumpf’s research on Tonpsychologie and Franz Brentano’s tradition of ‘act psychology’ were directly involved in this debate, opposing to Wilhelm Wundt’s conception of the discipline; this clearly came to light in Stumpf’s controversy with Carl Lorenz and Wundt on Tondistanzen. Stumpf’s concept of Verschmelzung and his views about consonance and concordance led him to some disputes with Theodor Lipps and Felix Krueger, lasting more than two decades. Carl Stumpf was responsible for education of a new generation of scholars during his teaching at the Berlin University: his pupils Wolfgang Köhler, Kurt Koffka and Max Wertheimer established the so-called ‘Berlin School’ and promoted the official Gestalt theory since the 1910s. After 1922 until 1938 they gave life and led together with other distinguished scientists the «Psychologische Forschung», a scientific journal in which ‘Gestalt laws’ and many other acoustical studies on different themes (such as sound localization, successive comparison, phonetic phenomena) were exposed. During the 1920s Erich Moritz von Hornbostel gave important contributions towards the definition of an organic Tonsystem in which sound phenomena could find adequate arrangement. Last section of the work contains descriptions of Albert Wellek’s studies, Kurt Huber’s vowel researches and aspects of melody perception, apparent movement and phi-phenomenon in acoustical field. The work contains also some considerations on the relationships among tone psychology, musical psychology, Gestalt psychology, musical aesthetics and musical theory. Finally, the way Gestalt psychology changed earlier interpretations is exemplified by the decisive renewal of perception theory, the abandon of Konstanzannahme, some repercussions on theory of meaning as organization and on feelings in musical experience.