764 research outputs found

    Self-gravitating Newtonian models of fermions with anisotropy and cutoff energy in their distribution function

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    Systems of self-gravitating fermions constitute a topic of great interest in astrophysics, due to the wide field of applications. In this paper, we consider the gravitational equilibrium of spherically symmetric Newtonian models of collisionless semidegenerate fermions. We construct numerical solutions by taking into account the effects of the anisotropy in the distribution function and considering the prevalence of tangential velocity. In this way, our models generalize the solutions obtained for isotropic Fermi-Dirac statistics. We also extend the analysis to equilibrium configurations in the classical regime and in the fully degenerate limit, recovering, for different levels of anisotropy, hollow equilibrium configurations obtained in Maxwellian regime. Moreover, in the limit of full degeneracy, we find a direct expression relating the anisotropy with the mass of the particles composing the system.Comment: 32 pages, 10 figures, accepted for publication in Physical Review

    Self-Gravitating Relativistic Models of Fermions with Anisotropy and Cutoff Energy in their Distribution Function

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    In this paper we study the equilibrium configurations of anisotropic self-gravitating fermions, by extending to general relativity the solutions obtained in a previous paper. This treatment also generalizes to anisotropic systems the relativistic self-gravitating Fermi gas model, by considering different degrees of anisotropy. We discuss some important characteristics of the models and the obtained density profiles, and generalize the relation between the anisotropy and the mass of particles in the relativistic regime. These relativistic models may also be applied to the study of superdense neutron stars with anisotropic pressure or super-Chandrasekhar white dwarfs generated by the presence of a magnetic field.Comment: 28 pages, 9 figures, 5 tables. Accepted for publication in Phys. Rev.

    A CHR-based Implementation of Known Arc-Consistency

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    In classical CLP(FD) systems, domains of variables are completely known at the beginning of the constraint propagation process. However, in systems interacting with an external environment, acquiring the whole domains of variables before the beginning of constraint propagation may cause waste of computation time, or even obsolescence of the acquired data at the time of use. For such cases, the Interactive Constraint Satisfaction Problem (ICSP) model has been proposed as an extension of the CSP model, to make it possible to start constraint propagation even when domains are not fully known, performing acquisition of domain elements only when necessary, and without the need for restarting the propagation after every acquisition. In this paper, we show how a solver for the two sorted CLP language, defined in previous work, to express ICSPs, has been implemented in the Constraint Handling Rules (CHR) language, a declarative language particularly suitable for high level implementation of constraint solvers.Comment: 22 pages, 2 figures, 1 table To appear in Theory and Practice of Logic Programming (TPLP

    Trop-2 inhibits prostate cancer cell adhesion to fibronectin through the β1 integrin-RACK1 axis.

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    Trop-2 is a transmembrane glycoprotein upregulated in several human carcinomas, including prostate cancer (PrCa). Trop-2 has been suggested to regulate cell-cell adhesion, given its high homology with the other member of the Trop family, Trop-1/EpCAM, and its ability to bind the tight junction proteins claudin-1 and claudin-7. However, a role for Trop-2 in cell adhesion to the extracellular matrix has never been postulated. Here, we show for the first time that Trop-2 expression in PrCa cells correlates with their aggressiveness. Using either shRNA-mediated silencing of Trop-2 in cells that endogenously express it, or ectopic expression of Trop-2 in cells that do not express it, we show that Trop-2 inhibits PrCa cell adhesion to fibronectin (FN). In contrast, expression of another transmembrane receptor, α(v) β(5) integrin, does not affect cell adhesion to this ligand. We find that Trop-2 does not modulate either protein or activation levels of the prominent FN receptors, β(1) integrins, but acts through increasing β(1) association with the adaptor molecule RACK1 and redistribution of RACK1 to the cell membrane. As a result of Trop-2 expression, we also observe activation of Src and FAK, known to occur upon β(1) -RACK1 interaction. These enhanced Src and FAK activities are not mediated by changes in either the activity of IGF-IR, which is known to bind RACK1, or IGF-IR\u27s ability to associate with β(1) integrins. In summary, our data demonstrate that the transmembrane receptor Trop-2 is a regulator of PrCa cell adhesion to FN through activation of the β(1) integrin-RACK1-FAK-Src signaling axis

    Uso integrato di sistemi di video monitoraggio e di misura delle prestazioni per migliorare il livello di sicurezza sul lavoro

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    Una delle tecnologie spesso presenti nelle aziende è rappresentata dai sistemi di videosorveglianza. Se da un lato l’efficacia di tali sistemi ai fini della sicurezza antintrusione è ampiamente riconosciuta, le potenzialità di un loro utilizzo per scopi di sicurezza sul lavoro non risultano ancora indagate. Il presente articolo illustra un progetto di ricerca applicata sviluppato dal gruppo di Impianti Industriali della Facoltà di Ingegneria dell’Università degli Studi di Brescia volto ad analizzare la potenziale utilità dell’utilizzo di sistemi di videosorveglianza per monitorare efficacemente le attività lavorative al fine di misurare, e quindi incrementare, il livello di salute e sicurezza sul lavoro. Nell’ambito del progetto, un sistema di video monitoraggio affiancato da un sistema di misura delle performance è stato implementato in un’azienda manifatturiera. La sperimentazione, resa possibile da un accordo tra parte datoriale e sindacale, ha consentito l’identificazione di interventi prioritari da attuare in azienda per il miglioramento del livello di sicurezza. Infatti, grazie all’analisi delle videoriprese è stato possibile individuare sia condizioni a rischio, che comportamenti a rischio o sicuri, connaturati con la specifica tipologia di attività dell’azienda. Le informazioni ed i dati così raccolti hanno consentito la quantificazione degli indicatori definiti dal sistema di misura delle prestazioni. Dall’analisi dell’andamento degli indicatori, si è evidenziato un aumento dei comportamenti sicuri durante il periodo di sperimentazione. Tale andamento può essere interpretato come conseguenza di breve periodo dell’effetto deterrenza legato all’installazione delle videocamere nei reparti produttivi. Una valutazione dell’efficacia di lungo periodo del sistema in termini di miglioramento del livello di sicurezza sul lavoro sarà possibile solamente a valle di ulteriori sperimentazioni. ------ Video surveillance systems represent one of the types of technology often available in companies. Even though the effectiveness of such systems for security reasons is well recognized, their potential for occupational safety reasons have not been investigated yet. This paper describes a research project, developed by the Industrial Plant group of the Engineering Faculty of the University of Brescia. The aim of the project is to analyse the potential of the use of video surveillance systems with the objective of effectively monitoring the working activity in order to measure, and therefore increase, the level of health and safety at work. Within the project, a video surveillance system coupled with a performance measurement system has been implemented in a manufacturing company. Through the experimentation of the system, that was possible because of an agreement between employer and unions, the priority interventions to implement in order to improve the safety level in the company have been identified. In fact, by means of the analysis of the video records, it was possible to identify both conditions at risk, and safe or at risk behaviours specific for the company. The gathered data made it possible to quantify the indicators included in the performance measurement system. A trend analysis of the indicators showed that the amount of safe behaviours increased during the experimentation period. This trend could be considered as a consequence in the short term of the deterrence effect connected to video cameras installation in the plant. An assessment of the long term effectiveness of the system in terms of safety level improvement will be possible only after further experimentations

    Design of experiments for the optimization of a new process for the stabilization of air pollution control residues

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    This work is part of the Cosmos-rice project (http://www.cosmos-rice.csmt.eu/), which was funded by the European Union under the Life+ program (LIFE11/ENV/IT000256). The aim of the Cosmos-rice project is to develop and optimise a new process, named Cosmos-rice process, for the stabilisation of Air Pollution Control (APC) residues coming from Municipal Solid Waste Incineration (MSWI) using rice husk ash as stabilizing agent (Bosio et al., 2014). The objective of this work is to present and discuss the optimisation of the Cosmos-rice process parameters by means of the statistical Design of Experiments (DoE) methodology. The DoE refers to the process of planning the experiments so that appropriate data that can be analysed by statistical methods can be collected, resulting in valid and objective conclusions (Montgomery, 2001). In the first part of this work, after a presentation of the Cosmos-rice process, the selection of the appropriate input and output factors (i.e. the variables that can influence the process performance and the variables selected to represent the process performance) is discussed. In particular, the input factors include the percentage of rice husk ash, the mixing temperature and time and the environmental conditions (air temperature and humidity) during the seasoning phase, while the output factors include the concentrations of Pb and Zn in the leachate of the treated APC residues. In the second part, the plan of experiments set up for the optimisation of the Cosmos-rice process is presented. In particular, after showing the levels adopted for each of the input parameters, the resulting plan of 16 experiments is shown. Finally, the results obtained from the experiments, carried out by the Chem4Tech laboratory of the University of Brescia (Italy), are analysed by means of the Multivariate Analysis of Variance (MANOVA). The MANOVA represents an extension of the univariate analysis of variance to the case of multiple dependent variables and allows for a direct test of the null hypothesis with respect to all the dependent variables in an experiment. Thanks to the statistical analysis, the relationships between input and output parameters have been identified, along with the best combination of the input factors levels. In particular, the environmental conditions during the seasoning phase have been found to be the parameter most affecting the effectiveness of the stabilisation process

    Kinematics and Kinetics of Bulgarian-Bag-Overloaded Sprints in Young Athletes

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    Background: Eective sprinting requires large acceleration capabilities. To accelerate, large amount of force must be produced and applied eectively. The use of dierent implements such as sleds and vests can increase the amount of force produced and alter sprinting eectiveness. We propose the use of increasing overload via the Bulgarian Bag (BB) as a means to modify athletes\u2019 sprint and acutely increase force and power production. Methods: 24 young athletes performed three sprints over 20 m in three dierent conditions: unloaded (BW) and loaded with BB weighing 2.5% (BB2.5) and 5% (BB5) of the athlete\u2019s body mass. Sprint times at 2.5, 5, 10, 15, and 20 m were acquired and used to compute the force\u2013velocity relationship for the sprints. Maximal velocity (V0), peak force (F0), peak power (PP), and decrease in ratio of force (DRF) were computed. Results: the additional load caused a decrease in sprint times (p < 0.05) and V0 (p = 0.028), conversely no dierences were found for F0 (p = 0.21), PP (p = 0.50), and DRF (p = 0.83). Conclusions: Based on those findings, BB can be an alternative method to eectively overload sprint training toward improving sprinting performance
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