1,358,732 research outputs found
Liolà
No full textGiuseppe Liotta ha curato la ragia teatrale dello spettacolo "Liolà" dal l'opera di Luigi Pirandello, nel piazzale del Kaos a Porto Empedocle. (Agrigento
Correlations Among Game of Thieves and Other Centrality Measures in Complex Networks
No full textSocial Network Analysis (SNA) is used to study the exchange of resources among individuals, groups, or organizations. The role of individuals or connections in a network is described by a set of centrality metrics which represent one of the most important results of SNA. Degree, closeness, betweenness and clustering coefficient are the most used centrality measures. Their use is, however, severely hampered by their computation cost. This issue can be overcome by an algorithm called Game of Thieves (GoT). Thanks to this new algorithm, we can compute the importance of all elements in a network (i.e. vertices and edges), compared to the total number of vertices. This calculation is done not in a quadratic time, as when we use the classical methods, but in polylogarithmic time. Starting from this we present our results on the correlation existing between GoT and the most widely used centrality measures. From our experiments emerge that a strong correlation exists, which makes GoT eligible as a centrality measure for large scale complex networks
A peek at the future internet
No full text\u3cp\u3eThe Internet connectivity machine is the generative engine of our modern digital society. It has been the launching pad of the Web (now the Web 2.0), truly the largest and most versatile information system ever built. While the Web phenomenon relentlessly continues, scientists worldwide are now living the dream of yet a more generative next-generation network. This chapter explores some prominent research directions, discussing the Internet of Things, context-aware networks, small world networks, scale-free networks, autonomic networks, dependable networks, the privacy vs. security dichotomy and the two facets of energy-efficient networks.\u3c/p\u3
Statistical Assessment of IP Multimedia Subsystem in a Softwarized Environment: A Queueing Networks Approach
No full textThe Next Generation 5G Networks can greatly benefit from the synergy between virtualization paradigms, such as the Network Function Virtualization (NFV), and service provisioning platforms such as the IP Multimedia Subsystem (IMS). The NFV concept is evolving towards a lightweight solution based on containers that, by contrast to classic virtual machines, do not carry a whole operating system and result in more efficient and scalable deployments. On the other hand, IMS has become an integral part of the 5G core network, for instance, to provide advanced services like Voice over LTE (VoLTE). In this paper we combine these virtualization and service provisioning concepts, deriving a containerized IMS infrastructure, dubbed cIMS, providing its assessment through statistical characterization and experimental measurements. Specifically, we: i) model cIMS through the queueing networks methodology to characterize the utilization of virtual resources under constrained conditions; ii) draw an extended version of the Pollaczek-Khinchin formula, which is useful to deal with bulk arrivals; iii) afford an optimization problem focused at maximizing the whole cIMS performance in the presence of capacity constraints, thus providing new means for the service provider to manage service level agreements (SLAs); iv) evaluate a range of cIMS scenarios, considering different queuing disciplines including also multiple job classes. An experimental testbed based on the open source platform Clearwater has been deployed to derive some realistic values of key parameters (e.g., arrival and service times)
Brevi note sul principio di gratuità nello sport.
No full textIl lavoro si sofferma su tutti i profili significativi dell'ordinamento sportivo (assetto istituzionale, soggetti, responsabilità, giustizia sportiva
An Experimental Evaluation and Characterization of VoIP over an LTE-A Network
No full textMobile telecommunications are converging towards all-IP solutions. This is the case of the Long Term Evolution (LTE) technology that, having no circuit-switched bearer to support voice traffic, needs a dedicated VoIP infrastructure, which often relies on the IP Multimedia Subsystem architecture. Most telecom operators implement LTE-A, an advanced version of LTE often marketed as 4{G} + , which achieves data rate peaks of 300 Mbps. Yet, although such novel technology boosts the access to advanced multimedia contents and services, telco operators continue to consider the VoIP market as the major revenue for their business. In this work, the authors propose a detailed performance assessment of VoIP traffic by carrying out experimental trials across a real LTE-A environment. The experimental campaign consists of two stages. First, we characterize VoIP calls between fixed and mobile terminals, based on a data-set that includes more than 750,000 data-voice packets. We analyze quality-of-service metrics such as round-trip time (RTT) and jitter, to capture the influence of uncontrolled factors that typically appear in real-world settings. In the second stage, we further consider VoIP flows across a range of codecs, looking at the trade-offs between quality and bandwidth consumption. Moreover, we propose a statistical characterization of jitter and RTT (representing the most critical parameters), identifying the optimal approximating distribution, namely the Generalized Extreme Value (GEV). The estimation of parameters through the Maximum Likelihood criterion, leads us to reveal both the short- and long-tail behaviour for jitter and RTT, respectively
Evolution of the in-patient hospital expenditure for the elderly in Italy: 1996-2001 comparison
No full textHospital expenditure constitutes the main component of public health spending in Western countries. Among the elements most frequently indicated as a cause of the increase in expenditure is the aging of the population. All Italian hospitalizations of more than one day during the year 2001, involving persons over 65 years of age, were analyzed on the basis of the data gathered by the Ministry of Health, starting from the hospital discharge forms. A comparison between the same data gathered for the 1996 has been carried out. The analysis reveals the impact of both the aging of the population and the use of more expensive technology on the cost increase related to 30 most frequent diagnosis-related groups (DRG) reported from the hospital discharge form. The comparison highlight the relation between the level of the fee assigned to each DRG and the size of the percentage variation of cases between 2001 and 1996 expressed by a linear regression model (R-2 = 0.45; p < 0.00 1). The results of the study rise questions about the impact of several factors on the increase of hospitalization cost: notably the DRG-based payment system could affect negatively the cost of inpatient services if an outside supervision will not allow the needed correction. (c) 2006 Elsevier Ireland Ltd. All fights reserved
Almost Bend-Optimal Planar Orthogonal Drawings of Biconnected Degree-3 Planar Graphs in Quadratic Time
No full textLet G be a degree-3 planar biconnected graph with n vertices. Let Opt(G) be the minimum number of bends in any orthogonal planar drawing of G.We show that G admits a planar orthogonal drawing D with at most Opt(G)+3 bends that can constructed in O(n 2) time. The fastest known algorithm for constructing a bend-minimum drawing of G has time-complexity O(n 5log n) and therefore, we present a significantly faster algorithm that constructs almost bend-optimal drawings
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