82 research outputs found
Use of incompatible displacement modes in a finite element model to analyze the dynamic behavior of unreinforced masonry panels
No full textA finite element model, where a non-conforming quadrilateral element is utilized, capable of analyzing the dynamic nonlinear behavior in a biaxial stress field of unreinforced masonry panels is presented. For the material, the linear elastic-plastic constitutive law is adopted. The formulation for the linear element and the extension for the linear elastic-plastic element are proposed. The solution is carried out by a direct step by step integration procedure in time domain, based on the Newmark method of the equilibrium equations, inclusive of inertial and damping actions, the latter evaluated using the Rayleigh hypothesis. The procedure was implemented in a computer program and verified by the analysis of an unreinforced masonry shear panel, the dynamic behavior of which was analyzed experimentally [1, 2]. The comparisons between the numeric results and laboratory test measurements show good agreement, proving the good performance of the non-conforming quadrilateral element also for time-dependent and markedly nonlinear analyses. In addition, the case of Parma Cathedral Bell-Tower subjected to a dynamic excitation available in literature, was analyzed using the proposed model. The same case was approached by a reliable finite element code [3], using quadratic serendipity elements and a more dense mesh than in the previous analysis. The results, in terms of kinematic parameters, stress and strain fields, etc. obtained by the two models, agree, proving that the use of a non-conforming quadrilateral element leads to analyses which are computationally economical and simple to use in input
L'importanza del calcio e i caseinofosfopeptidi: dalla nutrizione all'ingegneria tissutale
No full textBone is characterized by a physiologic turnover, in adult too: 0.05% of calcium, about 500 mg/die, is daily removed (osteoclastic activity) and hidden (osteoblastic activity). This mean that, in the adult, in about six years all bone minerals is changed.
Bone mass level remain the same when deposition rate is equal to reabsorption rate, that is when osteoclastic and osteoblastic activity are in equilibrium. This turnover is most fast in the infant, in this population all bone minerals is changed in about one year. About the total bone mass (Peak Bone Mass, PBM) is stored up within 18-20 years old. An inadequate intake of calcium in this period may lead to a low bone mineral density, which may have implications for bone health, notably risk of osteoporosis, in later life.
The PBM attainment constitutes a very important goal: grater bone mass in adult life means lower fractures in old age.
Calcium is an essential aliment: all calcium in the body comes from diet. Many foods contain calcium, but the amount of calcium, provided per 100 g or per serving, and is bioavailability vary considerably. The major source of calcium is milk and milk products.
The high bioavailability of calcium in milk is essential due to the presence of caseinphosphopeptides, CPPs, bioactive peptides which are formed by proteolytic digestium of casein in the ileum. Thanks to the presence, in their aminoacidic sequence, of an “acidic motive”, constitutes by three phosphorilated serine and two glutammate, Ser(P)-Ser(P)-Ser(P)-Glu-Glu, these peptides are able to prevent the formation of insoluble Ca-phosphate precipitates in the intestinal by complexing ionized calcium in soluble chelates which enhance the amount of intraluminal calcium available for transport across the mucosa by the non-saturable pathway.
Many searchers have proved their ability to increase the amount of calcium absorption and its utilization in bone tissue. Nevertheless, specially in humans searchers have not only obtained positive but also non-significant results. Long term clinical studies are necessary to better investigate CPPs role in humans.
More positive results are obtained in oral health: pre-formed CPPs and amorphous calcium phosphate nanocomplex (CPP-APC) have the potential to provide superior clinical efficacy in preventing dental caries, treating and reparing early stage of disease.
In present study we are demostrated that CPPs are able to iduce calcium uptake in osteoblasts, likewise they do in intestinal cells, both cell types involved in calcium metabolism in vivo. CPPs have instead no action in other cell types, like fibroblasts or neuronal cells. In particular, in osteoblast, kinetics and morphology CPPs cells response are different versus intestinal cells. This difference can be explained by different functions that they are assigned in vivo: intestinal cells are delegated to the calcium absorption instead osteoblast cells are delegated to the right calcemia maintenance.
Moreover, in osteoblasts, CPPs action is mediated by L-type calcium channel activation and this calcium influx in response to CPPs somministration activates cellular function, such as differenziating activity to mature osteoblasts stadium, likewise in the presence of vitamin D3, osteoblasts lineage physiological growth factor.
This results allow to suppose a role for CPPs not only as a functional food, as integration in prevention strategy of these pathologys and life styles characterized by an inadeguate calcium absorption and intake; but also as possible candidates in bone tissue engineering clinical strategies, for example by their integration in scaffolds. Nevertheless this is only the first step and more studies are necessary to better understand CPPs biological role and effect in vivo.
In last years many scientific reports have open the doors to a new research area, in which bioactive components from foods are the protagonists. They not only contribute to as adequate nutritional value, but generate advantages for health, reducing the risk to untle
several pathologys, without the contribution of body foreign chemical substances
Model order reduction for object-oriented models: a control systems perspective
No full textIn recent years several concepts and tools for modelling and simulation of nonlinear heterogeneous and multi-domain systems have been developed, speeding up to a great extent the process of an accurate analysis by simulation of increasingly complex technological systems. In parallel, for dimensioning and, above all, for control system design purposes, the need of models of reduced complexity
has emerged, together with the need of tools capable of extracting, from the overall dynamic
model, reduced models, representing the dominant behaviour. The paper reviews recent results in
nonlinear model order reduction, originally developed with reference to computer aided analysis and
design of electronic circuits, and puts them in a control system design oriented perspective, pointing
out interesting future research directions
Role of the Caseinophosphopeptides and Vitamin D on calcium uptake and cell functions in human cancer intestinal cell lines differentiated in culture : a possible correlation between nutrients and colon cancer. A.A. 2006-2007
No full textAutomatic classification of acquisition problems affecting fingerprint images in automated border controls
No full textAutomated Border Control (ABC) systems are technologies designed to increase the speed and accuracy of the identity verifications performed at international borders. A great number of ABCs deployed in different countries use fingerprint recognition techniques because of their high accuracy and user acceptability. However, the accuracy of fingerprint recognition methods can drastically decrease in this application context due to user-sensor interaction factors. This paper presents two main contributions. The first of them consists in an experimental evaluation performed to search the main negative aspects that could affect the usability and accuracy in ABCs based on fingerprint biometrics. The mainly considered aspects consists in the presence of luggage and cleanness of the finger skin. The second contribution consists in a novel approach for automatically identifying the type of user-sensor interaction that caused quality degradations in fingerprint samples. This method uses a specific feature set and computational intelligence techniques to detect non-idealities in the acquisition process and to suggest corrective actions to travelers and border guards. To the best of our knowledge, this is the first method in the literature designed to detect problems in user-sensor interaction different from improper pressures on the acquisition surface. We validated the proposed approach using a dataset of 2880 images simulating different scenarios typical of ABCs. Results shown that the proposed approach is feasible and can obtain satisfactory performance, with a classification error of 0.098
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