Search results for "Statistica"

The Mean-Field Limit for Solid Particles in a Navier-Stokes Flow

2008

We propose a mathematical derivation of Brinkman's force for a cloud of particles immersed in an incompressible viscous fluid. Specifically, we consider the Stokes or steady Navier-Stokes equations in a bounded domain Omega subset of R-3 for the velocity field u of an incompressible fluid with kinematic viscosity v and density 1. Brinkman's force consists of a source term 6 pi rvj where j is the current density of the particles, and of a friction term 6 pi vpu where rho is the number density of particles. These additional terms in the motion equation for the fluid are obtained from the Stokes or steady Navier-Stokes equations set in Omega minus the disjoint union of N balls of radius epsilo…

Tracking cruise passengers' consumption: An analysis of the relationships between onshore mobility and expenditure

2022

This paper analyzes the relationships between the spatial behaviour and destination expenditures of cruise tourists by integrating customer surveys and GPS tracking technology. Based on data collated in 2018 and 2019 in Copenhagen, cruise passenger expenditure was modelled via logistic regression, using socio-demographic characteristics and mobility-related variables. In order to map the spatial behaviour and the key characteristics of the itinerary followed, tracking data were synthesized into meaningful mobility variables. An analysis of stops was performed to identify locations with the potential highest expenditure density. The results indicated that spatial movement and, in particular,…

Il mercato del lavoro degli stranieri in Italia

2010

Gli studenti stranieri negli atenei italiani: un’analisi statistica dell’ultimo decennio.

2020

La mobilità studentesca universitaria è un fenomeno che, negli anni recenti, ha assunto una rilevanza notevole, in ambito nazionale. Essa è, infatti, prevalentemente oggetto di numerosi studi sui flussi migratori Sud-Centro e Sud-Nord degli studenti universitari italiani che scelgono sedi universitarie in regioni diverse da quella della propria residenza. Nel tempo le dimensioni numeriche di questi flussi sono divenute sempre più consistenti, con ripercussioni non certo trascurabili sul tessuto socioeconomico delle zone di origine. La mobilità studentesca gioca un ruolo rilevante nell’ampliamento della “forbice” tra le macro-aree regionali (Nord-Centro e Sud e Isole), ovvero quel divario so…

Food consumer models: The case of the responsible consumer

2017

The profile of the responsible consumer, that is, an individual whose purchases strive to satisfy altruistic aims above and beyond one’s merely personal consumer necessities, is closely correlated to the one’s socio-economic conditions. All subjective aspects considered, the correlation between responsible consumption in the agri-food sector and the level of education of the individual was studied herein by way of a statistical survey, conducted on a sample of 108 individuals. Likewise, the correlation between the level of responsible consumption and the average monthly expenditures was also elucidated. The study was carried out using the statistical software environment R and the resul…

High-resolution crystal structure of an avidin-related protein: insight into high-affinity biotin binding and protein stability.

2004

The chicken avidin gene belongs to an extended gene family encoding seven avidin-related genes (AVRs), of which only avidin is expressed in the chicken. The sequences of AVR4 and AVR5 are identical and the common protein (AVR4) has been expressed both in insect and bacterial systems. The recombinant proteins are similarly hyperthermostable and bind biotin with similarly high affinities. AVR4 was crystallized in the apo and biotin-complexed forms and their structures were determined at high resolution. Its tertiary and quaternary structures are very similar to those of avidin and streptavidin. Its biotin-binding site shows only a few alterations compared with those of avidin and streptavidin…

Confined binary two-dimensional colloidal crystals: Monte Carlo simulation of crack formation.

2010

Binary mixtures (A, B) of colloidal particles of different sizes in two dimensions may form crystals with square lattice structure (the A-particles occupying the white sites and the B-particles the black sites of a checkerboard). Confining such a system by two parallel 'walls' a distance D apart, long-range order in the direction parallel to the walls is stabilized by 'corrugated walls' that are commensurate with the lattice structure but destabilized by structureless 'hard walls', even if there is no misfit between the strip width D and the crystal lattice spacing. The crossover to quasi-one-dimensional behavior is studied by Monte Carlo simulations, analyzing Lindemann parameters and disp…

Formation of dislocation patterns: Computer simulations

1996

Dislocations patterns have been extensively studied by means of TEM. In parallel, theoretical approaches have been developed by using two methods; reaction diffusion schemes and computer simulation models. This distinction is not rigid since some computer models include the former approach in their evolution equations. Independently from the difficulties each approach presents in formulating the collective behavior of dislocations, the aim of these studies is to exhibit simple dislocation patterns as persistent slip bands and/or cellular organization. In this context, computer simulations brought a methodology which undoubtedly is a complement to the existing approaches for dislocations. Ne…

1980

A phenomenological theory of the Phase Distribution Chromatography (PDC)-separation effect is outlined and a theoretical equation for the measured PDC-calibration curves is given. Assuming a reversible-thermodynamical equilibrium in the polystyrene-PDC-column, only a relatively small part of the measured PDC-calibration curves could be explained: namely those running below their tangents. In order to explain the whole sigmoidal shape of the experimental curves, a theory of steady state in the system sol/gel was developed assuming deformation of the polymer coil near the gel front due to the stress related to the velocity gradient. The resulting dynamical flow-equilibrium differs highly from…

A review of the general theory of thermoelastic stress analysis

2003

Thermoelastic stress analysis (TSA) is now a well-known experimental technique providing information on the surface stress field in structures. Many studies have assessed the potential of the technique for a number of applications and some useful and detailed reviews of these investigations are available, focusing mainly on the experimental aspects related to the measurement of the thermoelastic signal. In this work, instead, a complete and detailed insight into the origins of the various forms of the equations describing the thermoelastic effect is given with reference to the concepts of the thermodynamic theory of a continuum. A discussion on the theory leading to the thermoelastic effec…