IRIS - UNIRSM (Univ. degli Studi della Repubblica di San Marino)
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Una dimensione complessa
No full textIl problema della continuità educativa, nelle sue dimensioni teoriche e operative, è apparso nel dibattito pedagogico sulla scuola italiana solo alla fine del secolo scorso. Lo stesso termine "continuità", che caratterizza da qualche tempo una discreta parte dei percorsi di aggiornamento e dei progetti di sperimentazione avviati nella scuola, fino a qualche anno fa non apparteneva sostanzialmente al lessico familiare dell'insegnante o, in ogni caso, ricopriva un ruolo decisamente secondario
Prevalenza di OSAS nella provincia di Pesaro-Urbino : dati derivati da uno screening su titolari di patente superiore e /o professionale afferenti alla CML dell'Area Vasta 1
No full textFree Vibration Analysis of Functionally Graded Porous Doubly-Curved Shells Based on the First-Order Shear Deformation Theory
No full textDue to some technical issues that can appear during the manufacturing process of Functionally Graded Materials (FGMs), it can be extremely difficult to produce perfect materials. Indeed, one of the biggest problems is the presence of porosities. For this purpose, the vibrational behavior of doubly-curved shells made of FGM including porosities is investigated in this paper. With respect to previous research, the porosity has been added to the mechanical model that characterizes the through-the-thickness distribution of the graded constituents and applied to doubly-curved shell structures. Few papers have been published on this topic. In fact, it is easier to find works related to one-dimensional structures and beam models that take account the effect of porosities. The First-order Shear Deformation Theory (FSDT) is considered as the theoretical framework. In addition, themechanical properties of the constituents vary along the thickness direction. For this purpose, two power-law distributions are employed to characterize their volume fraction. Strain components are established in an orthogonal curvilinear coordinate system and the governing equations are derived according to the Hamilton’s principle. Finally, Navier’s solution method is used and the numerical results concerning three different types of shell structures are presented
Influence of Winkler-Pasternak Foundation on the Vibrational Behavior of Plates and Shells Reinforced by Agglomerated Carbon Nanotubes
No full textThis paper aims to investigate the effect of the Winkler-Pasternak elastic foundation on the natural frequencies of Carbon Nanotube (CNT)-reinforced laminated composite plates and shells. The micromechanics of reinforcing CNT particles are described by a two-parameter agglomeration model. CNTs are gradually distributed along the thickness direction according to various functionally graded laws. Elastic foundations are modeled according to the Winkler-Pasternak theory. The theoretical model considers several Higher-order Shear Deformation Theories (HSDTs) based on the so-called Carrera Unified Formulation (CUF). The theory behind CNTs is explained in detail. The theoretical model presented is solved numerically by means of the Generalized Differential Quadrature (GDQ) method. Several parametric studies are conducted, and their results are discussed
Teacher agency: perspectives and limits
No full textAlthough many of the elements of the concept of teacher-agency have been present in Italian-language scientific debate for some time, the related international literature appears to be wholly refocusing its reflections to critically analyse the figure of the teacher in substantially new terms: according to a precious perspective in the light of the current opening to new areas of development of both initial and lifelong in-service teacher training. This paper, that discussed and referred to 17 articles on the issue of agency in teachers’ professional learning and development by selecting of the international literature, is divided into two parts. The first offers a pedagogical understanding of agency within a continuum in which this term can be interpreted in problematic way both as a teacher’s individual and collective characteristic and as a collective relational process. The second part, instead, reflects on teacher agency considering the interactions of this construct with individual and collective professional development and the school and community system as a whole
Bifid median nerve and carpal tunnel syndrome. An uncommon anatomical variation
No full textDear sir, one of the most common entrapment neuropathy syndromes in clinical practice is "Entrapment of median nerve in carpal tunnel" also called "Carpal tunnel syndrome (CTS)" (Aydin et al., 2007; Huisstede et al., 2010). This syndrome is caused by entrapment of the median nerve in the wrist (Preston and Shapiro, 2005) when the pressure increases in the carpal tunnel. A high division of the median nerve proximal to the carpal tunnel, also known as a bifid median nerve, is a rare anatomic variation that may be associated with CTS and with persistent median vessels (Lanz, 1977). This anatomic variation has an incidence of 0,8% to 2,3% in patients with CTS. Lanz (1977) has characterized this anatomic condition of the median nerve in the carpal tunnel. These anatomic variants have been classified into four groups: - Group 0: extraligamentous thenar branch (standard anatomy); - Group 1: variations of the course of the thenar branch; - Group 2: accessory branches at the distal portion of the carpal tunnel; - Group 3: divided or duplicated median nerve inside the carpal tunnel; - Group 4: accessory branches proximal to the carpal tunnel. During dissection of the wrist performed for the treatment of a CTS under local anesthesia, we found an anatomical variation of the median nerve that was divided in two branches inside the carpal tunnel (Group 3 of Lanz Classification) and in which its radial branch passed through its own compartment. The two parts of the nerve seems to be unequal in size (Fig. 1). Moreover the nerve passed in carpal tunnel associated with a median artery, so we classified this variation in the group 3b of Lanz Classification (Fig. 2). The persistence of median artery coexisting with a bifid median nerve has been widely reported in surgical literature (Lanz, 1977; Barbe et al., 2005). Before surgical intervention clinical evaluation of patient and electrophysiological examination showed no differences compared to a non bifid median nerve entrapment syndrome. In conclusion the bifid median nerve may facilitate compression of median nerve in the carpal tunnel because of its increased cross sectional area even if it has no electrophysiological or clinical differential diagnosis in case of CTS. The aim of this letter is aware the physicians in order to borne in mind the possible presence of a median nerve variation during dissection of carpal tunnel in order to avoid the damage of this non common anatomical structures
Finite Elements Based on Strong and Weak Formulations for Structural Mechanics: Stability, Accuracy and Reliability
No full textThe authors are presenting a novel formulation based on the Differential Quadrature (DQ) method which is used to approximate derivatives and integrals. The resulting scheme has been termed strong and weak form finite elements (SFEM or WFEM), according to the numerical scheme employed in the computation. Such numerical methods are applied to solve some structural problems related to the mechanical behavior of plates and shells, made of isotropic or composite materials.
The main differences between these two approaches rely on the initial formulation – which is strong or weak (variational) – and the implementation of the boundary conditions, that for the former include the continuity of stresses and displacements, whereas in the latter can consider the continuity of the displacements or both.
The two methodologies consider also a mapping technique to transform an element of general shape described in Cartesian coordinates into the same element in the computational space. Such technique can be implemented by employing the classic Lagrangian-shaped elements with a fixed number of nodes along the element edges or blending functions which allow an “exact mapping” of the element. In particular, the authors are employing NURBS (Not-Uniform Rational B-Splines) for such nonlinear mapping in order to use the “exact” shape of CAD designs
Teresa Noce Le avventure di Layka cagnetta spaziale
No full textAla fine degli anni Cinquanta Teresa Noce, figura di primo piano del rivoluzionarismo comunista, scrive una favola dedicata alla cagnetta Layka, il primo essere vivente lanciato nello spazio nel 1957. La favola è concepita come la scoperta nel cosmo di una utopica società socialista