Superiority of Simulator-Based Training Compared With Conventional Training Methodologies in the Performance of Transseptal Catheterization

ObjectivesThis study aims to compare the performance of electrophysiology fellows in transseptal catheterization (TSP-C) after conventional (Conv-T) or simulator training (Sim-T).BackgroundCurrent training for TSP-C, an increasingly used procedure, relies on performance on patients with supervision by an experienced operator. Virtual reality, a new training option, could improve post-training performance.MethodsFellows inexperienced in TSP-C were enrolled and randomly assigned to Conv-T or Sim-T. The post-training performance of each fellow was evaluated and scored in 3 consecutive patient-based procedures by an experienced operator blinded to the fellow's training assignment.ResultsFourteen fellows were randomized to Conv-T (n = 7) or to Sim-T (n = 7) and, after training, performed 42 TSP-Cs independently. Training time was significantly longer for Conv-T than for Sim-T (median 30 days vs. 4 days; p = 0.0175). The Conv-T fellows had significantly lower post-training performance scores (median 68 vs. 95; p = 0.0001) and a higher number of recurrent errors (median 3 vs. 0; p = 0.0006) when compared with Sim-T fellows.ConclusionsThe TSP-C training with virtual reality results in shorter training times and superior post-training performance

Strange metal behaviour from charge density fluctuations in cuprates

Besides the mechanism responsible for high critical temperature superconductivity, the grand unresolved issue of the cuprates is the occurrence of a strange metallic state above the so-called pseudogap temperature T-*. Even though such state has been successfully described within a phenomenological scheme, the so-called Marginal Fermi-Liquid theory, a microscopic explanation is still missing. However, recent resonant X-ray scattering experiments identified a new class of charge density fluctuations characterized by low characteristic energies and short correlation lengths, which are related to the well-known charge density waves. These fluctuations are present over a wide region of the temperature-vs-doping phase diagram and extend well above T-*. Here we investigate the consequences of charge density fluctuations on the electron and transport properties and find that they can explain the strange metal phenomenology. Therefore, charge density fluctuations are likely the long-sought microscopic mechanism underlying the peculiarities of the metallic state of cuprates. The strange metallic state of cuprates occurring in a broad region of their phase diagram outside the superconducting and pseudogapped regions remains a mystery. Here the authors consider the charge density fluctuations recently discovered in resonant X-ray experiments as a possible source of scattering and show that these fluctuations can account for the strange metallic behavior

La famiglia transnazionale 3. Dalle Ande agli Appennini: contesti di partenza e migrazioni

L’America Meridionale è spesso percepita, in Europa, come una realtà omogenea e definita, viceversa essa presenta una rara varietà di caratteri climatici, etnici, sociali, politici, giuridici, tanto da essere indicata un “continente mondo”. Il volume vuole dare ragione di questa diversità offrendo un'analisi interdisciplinare utile alla comprensione e contestualizzazione delle migrazioni che oggi coinvolgono persone e famiglie che da questi territori si dirigono verso l’Europa e in particolare l’Italia. In tale contesto, queste pagine offrono un approfondimento sui paesi della costa pacifica e del rilievo andino, completando il quadro dell’analisi sulla famiglia transnazionale proposta nei precedenti volumi dedicati all’Ecuador e al Perù

Accogliere gli immigrati. Testimonianze di inclusione socio-economica

Il volume presenta i risultati di un'indagine sull'inclusione socio-economica dei migranti in Italia. La ricerca ha preso in considerazione due casi-studio: quello della comunità romena residente nella provincia di Roma e quello della comunità boliviana presente a Bergamo. Attraverso interviste a testimoni privilegiati e la ricostruzione dei percorsi dei migranti, si sono individuati e analizzati i fallimenti ma anche i successi degli itinerari intrapresi, evidenziando gli aspetti su cui oggi è necessario lavorare ai fini di una migliore integrazione

Preliminary Sizing of the Wing-Box Structure by Multi-Level Approach

The paper describes a procedure, dedicated to the preliminary sizing of an aircraft wing-box, based on a two level decomposition and on two independent optimizations. An engineering approach is followed and the most suitable model is exploited at each level in order to generate information about the wing-box structure without the need of a previous knowledge, a very important feature in the case of unconventional structures. The first level uses a commercial structural multidisciplinary optimization code and a stick model of the wing primary structure to minimize the structural mass under global design constraints; a set of physical design variables are used referring to a schematic representation of the cross-section in terms of equivalent axial thickness supporting pure axial stress and the thickness of a box resisting to both axial and shear stresses. The second level, based on a genetic optimization, provides the minimum mass optimal design of the wing cross sections, in terms of local design variables, which safely support the internal loads supplied by the first level, under local constraints, e.g. panel buckling and stiffeners crippling, providing also a cross section stiffness in compliance with the first level. The reported example, concerning the B747-100 wing structure, shows the capability of the approach to predict the structural weight of the wing box, an information to be used mainly in an early stage of the aircraft design, and to suggest a set of cross sections design solutions all in compliance with both global and local requirements

Multilevel Structural Optimization for Preliminary Wing-Box Weight Estimation

This paper deals with the weight estimation of the wing box of a commercial aircraft by means of a procedure suitable for very large liners and/or unconventional configurations for which statistical data and empirical formulas may not be sufficiently reliable. Attention is focused on the need to account for aeroelastic interaction from a very preliminary stage of the design cycle. The procedure exploits the first of three levels of a multilevel structural optimization system conceived for the preliminary design of the wing primary structure and a simplified evaluation of the cross-sectional properties. The comparison between weight estimates obtained with the present procedure and predictions supplied by available literature shows a satisfactory agreement