1,720,998 research outputs found
The tumours of the endocrine pancreas
No full textTumours of the endocrine pancreas are rare entities with evidence of endocrine cell differentiation. Immunohistochemistry is the most reliable method used to study such tumours either for the identification of their hormonal product(s) or to explore functional aspects like proliferative activity or oncoprotein overexpression (e.g. p53). Most of the endocrine tumours of the pancreas are well differentiated and behave as benign or low grade malignant tumours. Poorly differentiated (small cell) endocrine carcinomas are rare and have a poor prognosi
Thermal convection in monodisperse and bidisperse granular gases: A simulation study
No full textWe present results of a simulation study of inelastic hard disks vibrated in a vertical container. An event-driven molecular dynamics method is developed for studying the onset of convection. Varying the relevant parameters (inelasticity, number of layers at rest, intensity of the gravity) we are able to obtain a qualitative agreement of our results with recent hydrodynamical predictions. Increasing the inelasticity, a first continuous transition from the absence of convection to one convective roll is observed, followed by a discontinuous transition to two convective rolls, with hysteretic behavior. At fixed inelasticity and increasing gravity, a transition from no convection to one roll can be evidenced. If the gravity is further increased, the roll is eventually suppressed. Increasing the number of monolayers the system eventually localizes mostly at the bottom of the box: in this case multiple convective rolls as well as surface waves appear. We analyze the density and temperature fields and study the existence of symmetry breaking in these fields in the direction perpendicular to the injection of energy. We also study a binary mixture of grains with different properties (inelasticity or diameters). The effect of changing the properties of one of the components is analyzed, together with density, temperature, and temperature ratio fields. Finally, the presence of a low fraction of quasielastic impurities is shown to determine a sharp transition between convective and nonconvective steady states
Granular gases in compartmentalized systems
No full textThis contribution considers recent developments in understanding the behaviour of vibro-fluidized beads in containers partitioned into several connected chambers. The system is studied theoretically by means of a phenomenological mean-field approach. The equations governing the evolution of the average occupancy and the average kinetic energy of each compartment are derived by means of a simplified treatment of the Boltzmann equation. Some applications of the method are presented. These include the study of a simple granular gas in a many-compartment container and a binary granular mixture in a two-compartment container
Participatory Online Surveillance as a Supplementary Tool to Sentinel Doctors for Influenza-Like Illness Surveillance in Italy
No full textThe monitoring of seasonal influenza yearly epidemics remains one of the main activity of national syndromic surveillance systems. The development of internet-based surveillance tools has brought an innovative approach to seasonal influenza surveillance by directly involving self-selected volunteers among the general population reporting their health status on a weekly basis throughout the flu season. In this paper, we explore how Influweb, an internet-based monitoring system for influenza surveillance, deployed in Italy since 2008 has performed during three years from 2012 to 2015 in comparison with data collected during the same period by the Italian sentinel doctors surveillance system
Systemic liquidity contagion in the European interbank market
Full text linkSystemic liquidity risk, defined by the International Monetary Fund as "the risk of simultaneous liquidity difficulties at multiple financial institutions," is a key topic in financial stability studies and macroprudential policy-making. In this context, the complex web of interconnections of the interbank market plays the crucial role of allowing funding liquidity shortages to propagate between financial institutions. Here, we introduce a simple yet effective model of the interbank market in which liquidity shortages propagate through an epidemic-like contagion mechanism on the network of interbank loans. The model is defined by using aggregate balance sheet information of European banks, and it exploits country and bank-specific risk features to account for the heterogeneity of financial institutions. Moreover, in order to obtain the European-wide topology of the interbank network, we define a block reconstruction method based on the exchange flows between the various countries. We show that the proposed contagion model is able to estimate systemic liquidity risk across different years and countries. Results suggest that our effective contagion approach can be successfully used as a viable alternative to more realistic but complicated models, which not only require more specific balance sheet variables with high time resolution but also need assumptions on how banks respond to liquidity shocks
Bistable clustering in driven granular mixtures
No full textThe behavior of a bidisperse inelastic gas vertically shaken in a cornpartmentalized container is investigated using two different approaches: the first is a mean-field dynamical model, which treats the number of particles in the two compartments and the associated kinetic temperatures in a self-consistent fashion; the second is an event-driven numerical simulation. Both approaches reveal a non-stationary regime, which has no counterpart in the case of monodisperse granular gases. Specifically, when the mass difference between the two species exceeds a certain threshold the populations display a bistable behavior, with particles of each species switching back and forth between compartments. The reason for such all unexpected behavior is attributed to the interplay of kinetic energy non-equipartition due to inelasticity with the energy redistribution induced by collisions. The mean-field model and numerical simulation are found to agree qualitatively
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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