1,721,170 research outputs found
Repeatability and reproducibility of XRPD measurements via Diffraction Instrumental Monotoring: results of the Italian Round Robin on KCl
No full textVI European Powder Diffraction Conference, Budapes
Dal Commonitorium al De vitiis: per un'esegesi del testo di Orienzio
Full text linkIl contributo raccoglie alcune proposte interpretative dell'opera orienziana, invitando a considerare in autonomia la sezione centrale dedicata alla riflessione sui vizi e i peccati, guardando alla quale si comprende il senso pieno dell'intera trattazione; si analizzano, inoltre, le fonti bibliche e patristiche, oltre che le idee teologiche di base, che costituiscono l'ambiente di gestazione del pensiero orienziano
Displacement vs. non-displacement axially loaded pile behaviour in sand from centrifuge tests
No full textRisposta sismica locale: la MS come strumento discriminante per l’utilizzo di approcci semplificati o di specifiche analisi
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Evaluation of site effects: development of the semiquantitative abacuses in Regione Lazio (Italy)
No full textA discrete particle model reproducing collective dynamics of a bee swarm
Full text linkIn this article, we present a microscopic discrete mathematical model describing collective dynamics of a bee swarm. More specifically, each bee is set to move according to individual strategies and social interactions, the former involving the desire to reach a target destination, the latter accounting for repulsive/attractive stimuli and for alignment processes. The insects tend in fact to remain sufficiently close to the rest of the population, while avoiding collisions, and they are able to track and synchronize their movement to the flight of a given set of neighbors within their visual field. The resulting collective behavior of the bee cloud therefore emerges from non-local short/long-range interactions. Differently from similar approaches present in the literature, we here test different alignment mechanisms (i.e., based either on an Euclidean or on a topological neighborhood metric), which have an impact also on the other social components characterizing insect behavior. A series of numerical realizations then shows the phenomenology of the swarm (in terms of pattern configuration, collective productive movement, and flight synchronization) in different regions of the space of free model parameters (i.e., strength of attractive/repulsive forces, extension of the interaction regions). In this respect, constraints in the possible variations of such coefficients are here given both by reasonable empirical observations and by analytical results on some stability characteristics of the defined pairwise interaction kernels, which have to assure a realistic crystalline configuration of the swarm. An analysis of the effect of unconscious random fluctuations of bee dynamics is also provided
Prove di trazione su pali modello in sabbia: Modellazione fisica in centrifuga geotecnica.
No full textCollective migration and patterning during early development of zebrafish posterior lateral line
Full text linkThe morphogenesis of zebrafish posterior lateral line (PLL) is a good predictive model largely used in biology to study cell coordinated reorganization and collective migration regulating pathologies and human embryonic processes. PLL development involves the formation of a placode formed by epithelial cells with mesenchymal characteristics which migrates within the animal myoseptum while cyclically assembling and depositing rosette-like clusters (progenitors of neuromast structures). The overall process mainly relies on the activity of specific diffusive chemicals, which trigger collective directional migration and patterning. Cell proliferation and cascade of phenotypic transitions play a fundamental role as well. The investigation on the mechanisms regulating such a complex morphogenesis has become a research topic, in the last decades, also for the mathematical community. In this respect, we present a multiscale hybrid model integrating a discrete approach for the cellular level and a continuous description for the molecular scale. The resulting numerical simulations are then able to reproduce both the evolution of wild-type (i.e. normal) embryos and the pathological behaviour resulting form experimental manipulations involving laser ablation. A qualitative analysis of the dependence of these model outcomes from cell-cell mutual interactions, cell chemical sensitivity and internalization rates is included. The aim is first to validate the model, as well as the estimated parameter values, and then to predict what happens in situations not tested yet experimentally. This article is part of the theme issue 'Multi-scale analysis and modelling of collective migration in biological systems'
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