Effect of Physical Exercise on the Release of Microparticles with Angiogenic Potential

Cellular communication has a fundamental role in both human physiological and pathological states and various mechanisms are involved in the crosstalk between organs. Among these, microparticles (MPs) have an important involvement. MPs are a subtype of extracellular vesicles produced by a variety of cells following activation or apoptosis. They are normally present in physiological conditions, but their concentration varies in pathological states such as cardiovascular disease, diabetes mellitus, or cancer. Acute and chronic physical exercise are able to modify MPs amounts as well. Among various actions, exercise-responsive MPs affect angiogenesis, the process through which new blood vessels grow from pre-existing vessels. Usually, the neo vascular growth has functional role; but an aberrant neovascularization accompanies several oncogenic, ischemic, or inflammatory diseases. In addition, angiogenesis is one of the key adaptations to physical exercise and training. In the present review, we report evidence regarding the effect of various typologies of exercise on circulating MPs that are able to affect angiogenesis

The Influence of Maturity Status on Anthropometric Profile and Body Composition of Youth Goalkeepers

The anthropometric profile assessment is an important aspect to consider during the growth stages of youth sport practitioners due to its usefulness in controlling maturity status and overall health. We performed an anthropometric profile evaluation in a sample of youth goalkeepers (n = 42) during a training camp, dividing them into three categories based on their years from peak height velocity (YPHV). We also checked if the selection of goalkeepers was associated with the birth quartile. The results showed that most of the participants’ anthropometric parameters followed the normal trend according to the maturation stages. However, several subjects showed an overweight/obese condition and/or high waist circumference. Non-optimal values were found, mostly in the group of goalkeepers around the PHV. In addition, no selection based on birth quartile was seen. Therefore, the anthropometric profile and body composition of youth goalkeepers are physiologically affected by maturity status. However, several subjects were found to be overweight/obese and at cardiometabolic risk, suggesting that children and adolescents, although practicing sport, should pay attention to potentially contributing factors such as the attainment of the recommended levels of physical activity, lowering sedentary time, and adopt a healthy lifestyle

Metodo Energetico agli Elementi di Contorno per problemi di Elastodinamica 2D nel dominio del tempo

Questa tesi è incentrata sull’applicazione del Boundary Element Method di tipo energetico per la risoluzione di problemi elastodinamici, con propagazione esterna ad un ostacolo aperto o ad una regione limitata da un contorno chiuso Lipschitziano. A partire dalla soluzione fondamentale di Green, il problema differenziale può essere riscritto in termini di diversi tipi di equazioni integrali di contorno (BIE), utili alla risoluzione di problemi con dato di Dirichlet o di Neumann sull’ostacolo e ridefinite in formulazioni deboli nel dominio del tempo, basate sull’energia del sistema. Le formulazioni deboli considerate, una volta discretizzate, producono sistemi lineari con matrici triangolari inferiori di Toeplitz, i cui elementi sono integrali quadrupli in spazio e tempo. In una consistente parte di tesi vengono discusse le formule di quadratura impiegate nell’approssimazione numerica, ad alta precisione, degli integrali di contorno, tenendo conto delle singolarità caratteristiche degli operatori integrali: O(log(r)) per l’operatore di strato singolo, O(1/r) per quello di doppio strato e O(1/r^2) per quello ipersingolare. Inoltre, un accurato studio del dominio di integrazione in variabili locali permette di evitare l’integrazione diretta delle funzioni Heaviside, comuni a tutti i tipi di nuclei integrali. È inoltre descritta l’analisi teorica basata sulla rappresentazione indiretta di strato singolo, con l’obbiettivo di dimostrare proprietà di continuità e coercività della forma bilineare associata, e numerosi test numerici vengono presentati a conferma della correttezza e dell’efficacia del BEM energetico, mostrando in particolare soluzioni delle BIE stabili nel tempo. In alternativa alla decomposizione uniforme dell’ostacolo, vengono presi in considerazione diversi tipi di discretizzazione spaziale, con l’obbiettivo di carpire il comportamento asintotico della soluzione della BIE di strato singolo verso gli estremi di un ostacolo aperto o nei pressi degli angoli di un arco poligonale chiuso. In particolare, l’incognita di tale BIE, in un problema di tipo Dirichlet, ha un andamento O(r^-1/2) agli estremi di un segmento e si comporta come O(r^-w) nei pressi di un angolo, la cui ampiezza è legata all’esponente w. Un raffinamento di tipo geometrico o algebrico della mesh vicino a questi punti critici dell’ostacolo migliora la convergenza verso la soluzione della BIE: viene mostrata pertanto un’analisi approfondita del decadimento dell’errore in norma energetica rispetto all’uso di vari metodi di approssimazione, verificando numericamente l’andamento stimato dell’errore per ogni tipo di discretizzazione (tecnica h, tecnica p e tecnica h-p). Considerazioni e test numerici vengo presentati anche per la formulazione indiretta con operatore ipersingolare applicata a problemi di Neumann. Infine, osserviamo che, con l’utilizzo di funzioni di base lagrangiane, la matrice BEM è composta da blocchi temporali che diventano generalmente densi con l’avanzare del tempo. La memoria totale occupata pertanto è O(M^2N), con M ed N gradi di libertà rispettivamente spaziali e temporali. Questo rende l’applicazione del BEM onerosa per problemi realistici su larga scala. In questa tesi viene proposta una tecnica veloce, basata sull’Adaptive Cross Approximation (ACA), che permette un’approssimazione a basso rango dei blocchi temporali, riducendo drasticamente il numero degli elementi originari della matrice da valutare. Ciò porta anche ad una riduzione della memoria richiesta, dei tempi di assemblaggio e di risoluzione del sistema lineare. La fattibilità della strategia è teoricamente dimostrata nello specifico per la formulazione debole di singolo strato e diversi test numerici sono presentati e discussi.This thesis deals with the application of the Energetic Boundary Element Method (BEM) for the resolution of elastodynamic problems in bidimensional unbounded domains, outside an open regular obstacle or external to a region with a closed Lipschitz boundary. Starting from the fundamental Green’s tensor, the differential problem is rewritten in terms of different Boundary Integral Equations (BIEs), suitable to solve problems equipped by Dirichlet or Neumann datum at the boundary. These BIEs are then set in a space-time weak form, based on energy arguments, and numerically solved by means of Energetic BEM. All the considered weak BIEs, once discretized, give rise to linear systems with lower triangular Toeplitz matrix, whose entries are quadruple space-time integrals. A consistent part of the thesis discusses the quadrature formulas employed to compute numerically the integrals in space variables on the boundary with high accuracy, and taking into account the characteristic space singularities: O(log(r)) for the single layer integral operator, O(1/r) for the double layer integral operator and O(1/r^2) for the hypersingular integral operator. Moreover, an accurate study of the integration domain in local variables allows to overcome the issues of the integration of peculiar step functions that feature all the integral kernels. A theoretical analysis of the indirect weak form with single layer operator has been executed, in order to prove properties of coercivity and continuity of the associated energetic bilinear operator, and numerous numerical results are presented to confirm the correctness and the effectiveness of the energetic BEM, showing in particular long time stability of the BIE solutions. In alternative to the uniform decomposition of the obstacle, I have taken into account different types of discretization that turn out to be useful, for instance, to catch the asymptotic behaviour of the single layer BIE solution at the endpoints of an open obstacle or at the corners of a polygonal closed arc. In particular, the solution of this BIE for a Dirichlet problem behaves like O(r^-1/2) at the extremes of a crack and like O(r^-w) near a corner, with the exponent w related to the amplitude of the angle. Meshes geometrically or algebraically refined at these critical points improve the convergence towards the solution: therefore, an in dept analysis of the error decay in energy norm is shown with respect to the type of refinement (h-version, p-version and hp-version have been in particular considered). The numerical results verify the theoretical slope of the estimated error for the various discretization method. Similar remarks and numerical experiments are also presented for Neumann problems, solved by indirect weak form depending on the hypersingular operator. Lastly, I take into account the following issue: when standard Lagrangian basis functions are considered, the BEM matrices are made by time-dependent blocks that are generally fully populated. The overall memory cost of the energetic BEM is O(M^2N), M and N being the number of space and time degrees of freedom, respectively. This can prevent the application of BEM to large scale realistic problems. Thus, in this thesis, a fast technique, based on the Adaptive Cross Approximation (ACA), is provided in order to get a low rank approximation of the time blocks, reducing drastically the number of the original entries to be evaluated. This procedure leads to a drop in the computational time, spent for the assembly and the resolution of the linear system, and in the memory storage requirements, which are generally relevant. The effectiveness of this strategy is theoretically proved for the single layer weak formulation and several numerical results are presented and discussed