Theoretical Models for Video on Demand Services on Peer-to-Peer Networks

Peer-to-peer networks (P2Ps) are becoming more and more popular in video content delivery services, such as TV broadcast and Video on Demand (VoD), thanks to their scalability feature. Such characteristic allows for higher numbers of simultaneous users at a given server load and bandwidth with respect to alternative solutions. However, great efforts are still required to study and design reliable and QoS-guaranteed solutions. In this paper, within the scenario of P2P-based VoD services, we study the phenomenon of peer churns and propose four models of the peer behaviour to evaluate its impact on the system performance, which are based on the Gilbert-Elliot chain, the fluidic representation of the user behavior, and a queuing analysis of the system. The models are compared by computing the resources the system has to add on top of the P2P network to satisfy all the download requests. Simulations show important relationships between playback buffer length, peer request rate, peer average lifetime, and server upload rate

Architectures and technologies for quality of service provisioning in next generation networks

A NGN is a telecommunication network that differs from classical dedicated networks because of its capability to provide voice, video, data and cellular services on the same infrastructure (Quadruple-Play). The ITU-T standardization body has defined the NGN architecture in three different and well-defined strata: the transport stratum which takes care of maintaining end-to-end connectivity, the service stratum that is responsible for enabling the creation and the delivery of services, and finally the application stratum where applications can be created and executed. The most important separation in this architecture is relative to transport and service stratum. The aim is to enable the flexibility to add, maintain and remove services without any impact on the transport layer; to enable the flexibility to add, maintain and remove transport technologies without any impact on the access to service, application, content and information; and finally the efficient cohesistence of multiple terminals, access technologies and core transport technologies. The Service Oriented Architecture (SOA) is a paradigm often used in systems deployment and integration for organizing and utilizing distributed capabilities under the control of different ownership domains. In this thesis, the SOA technologies in network architetures are surveyed following the NGN functional architecture as defined by the ITU-T. Within each stratum, the main logical functions that have been the subject of investigation according to a service-oriented approach have been highlighted. Moreover, a new definition of the NGN transport stratum functionalities according to the SOA paradigm is proposed; an implementation of the relevant services interfaces to analyze this approach with experimental results shows some insight on the potentialities of the proposed strategy. Within NGN architectures research topic, especially in IP-based network architectures, Traffic Engineering (TE) is referred to as a set of policies and algorithms aimed at balancing network traffic load so as to improve network resource utilization and guarantee the service specific end-to-end QoS. DS-TE technology extends TE functionalities to a per-class basis implementation by introducing a higher level of traffic classification which associates to each class type (CT) a constraint on bandwidth utilization. These constraints are set by defining and configuring a bandwidth constraint (BC) model whih drives resource utilization aiming to higher load balancing, higher QoS performance and lower call blocking rate. Default TE implementations relies on a centralized approach to bandwidth and routing management, that require external management entities which periodically collect network status information and provide management actions. However, due to increasing network complexity, it is desiderable that nodes automatically discover their environment, self-configure and update to adapt to changes. In this thesis the bandwidth management problem is approached adopting an autonomic and distributed approach. Each node has a self-management module, which monitors the unreserved bandwidth in adjacent nodes and adjusts the local bandwidth constraints so as to reduce the differences in the unreserved bandwidth of neighbor nodes. With this distributed and autonomic algorithm, BC are dinamically modified to drive routing decision toward the traffic balancing respecting the QoS constraints for each class-type traffic requests. Finally, Video on Demand (VoD) is a service that provides a video whenever the customer requests it. Realizing a VoD system by means of the Internet network requires architectures tailored to video features such as guaranteed bandwidths and constrained transmission delays: these are hard to be provided in the traditional Internet architecture that is not designed to provide an adequate quality of service (QoS) and quality of experience (QoE) to the final user. Typical VoD solutions can be grouped in four categories: centralized, proxy-based, Content Delivery Network(CDN) and Hybrid architectures. Hybrid architectures combine the employment of a centralized server with that of a Peer-to-peer (P2P) network. This approach can effectively reduce the server load and avoid network congestions close to the server site because the peers support the delivery of the video to other peers using a cache-and-relay strategy making use of their upload bandwidth. Anyway, in a peer-to-peer network each peer is free to join and leave the network without notice, bringing to the phenomena of peer churns. These dynamics are dangerous for VoD architectures, affecting the integrity and retainability of the service. In this thesis, a study aimed to evaluate the impact of the peer churn on the system performance is proposed. Starting from important relationships between system parameters such as playback buffer length, peer request rate, peer average lifetime and server upload rate, four different analytic models are proposed

An Updated Review of Cribriform Carcinomas with Emphasis on Histopathological Diagnosis and Prognostic Significance

Cribriform is a histopathological term used to describe a neoplastic epithelial proliferation in the form of large nests perforated by many quite rounded different-sized spaces. This growth pattern may be seen in carcinomas arising in different organs, and shows important prognostic implications. Therefore, recent data in literature suggest that cribriform carcinoma is a histologically and clinically distinctive type of tumour that should be separated from other similar tumour types. In this article, the pathology of cribriform adenocarcinoma of the prostate, lung, breast, stomach, colon, thyroid, and skin is discussed with particular reference to morphologic and immunohistochemical features, differential diagnosis, and clinical behaviour

Effect of corn and beet pulp based concentrate on ruminal parameters in wethers fed with fresh forage

Four wethers housed in individual pens and fitted with ruminal cannulae were grouped (two wethers per group) and fed fresh forage (Italian ryegrass, Lolium multiflorum) with either beet pulp (BP) or corn based concentrate (C) as supplements, using a crossover experimental design. The experiment was carried out during two experimental periods: the growing phase (early spring, G) and the reproductive phase (late spring, R) of the ryegrass. The diet of each animal was changed as the grass moved from the vegetative phase to the reproductive phase. The intake, the chemical composition of the diet and ruminal parameters such as pH, ammonia and volatile fatty acid were determined. Total dry matter intake (DMI) decreased from early to late spring (1081 vs 767 g/d; P<0.0001). Herbage DMI in particular decreased more (811 vs 543 g/d; P<0.05) than concentrate DMI (271 vs 224 g/d; P<0.054). There were marked differences in the chemical composition of the diet in wethers fed with the forage from early or late spring. This was because of changes in the characteristics of the forage. In detail, DM, NDF and ADF increased from early to late spring while CP, and EE decreased (P<0.05). Ruminal pH was lower in G than in R (6.24 vs 6.57, P<0.05). The concentrate used had no effect on the pH value. The ammonia concentration in the rumen fluid decreased from early to late spring (10.79 vs 6.68 mg/100 ml, P<0.05) and it was not influenced by the source of carbohydrates from the concentrate. VFA rumen fluid concentration increased (P<0.05) after feeding and decreased before the second meal. In the rumen fluid, the maximum total VFA concentration and the lowest pH were observed 2 h after the morning meal. Acetate and butyrate concentrations in the rumen fluid were influenced by the period (P<0.05) but not by the concentrate source. By contrast, the concentrate source significantly influenced the rumen fermentation patterns of propionate and VFA ratios, with higher propionic acid and lower acetate to propionate ratios in C than BP. This highlights the importance of the carbohydrate source in supplements for pasture based rations which varied according to the proportion of beet pulp and corn in the ingested diet

Photodetectors fabricated from a self-assembly of a deoxyguanosine derivative

A metal–semiconductor–metal (MSM) photodetector has been fabricated using as the semiconductor, a self-assembled layer of a DNA basis, namely a deoxyguanosine derivative, deposited between two gold electrodes. These were defined lithographically on a SiO2 substrate, separated by a distance of about 120 nm. The resulting self-assembled guanosine crystal has been deposited in such a way to achieve striking semiconducting properties. We show that with these conditions, the I–V characteristics are independent of the crystal orientation. The device shows a high current response (differential resistance at room temperature ranges in MΩ) which is symmetric with respect to bias sign and dependent on the illumination conditions. This behavior can be explained by taking into account the standard MSM theory and its applications as a photodetector

Biomolecular electronic devices based on self-organized deoxyguanosine nanocrystals.

We report on a new class of hybrid electronic devices based on a DNA nucleoside (deoxyguanosine lipophilic derivative) whose assembled polymeric ribbons interconnect a submicron metallic gate. The device exhibits large conductivity at room temperature, rectifying behavior and strong current-voltage hysteresis. The transport mechanism through the molecules is investigated by comparing films with different self-assembling morphology. We found that the main transport mechanism is connected to pi-pi interactions between guanosine molecules and to the formation of a strong dipole along ribbons, consistently with the results of our first-principles calculations

Evidence of immune system morpho-functional damages induced by Cadmium in Apis mellifera

In previous researches severe damages induced by Cadmium (an ubiquitary environmental pollutant whose intracellular oxidative effects are increasingly lethal) exposure in human have been demonstrated. Morphologic effects were observed in Central Nervous System, liver, kidney, placenta. Recently, the involvement of immune system in Cadmium intoxication was demonstrated in mammalians; we, therefore, tried to evidence such effect in a simple model as Apis Mellifera. In this animal the immune system is represented by “fat bodies” which produce proteins active in defense against pathogenic agents. It is important to stress out that a dangerous syndrome causing the collapse of Apis mellifera hives has intensified recently, in Europe and North America. Current research in this field is oriented towards identifying a synergy of contributing factors to the weakening of the hive. In this paper, we aim to determine whether contamination by cadmium may have an immunosuppressive effect on the insect. Preliminary results denote that the heavy metal causes a severe damage in fat bodies, leading to substantial immunodeficiency in exposed bees, suggesting that in polluted areas the hives may have difficulty in dealing with pests and pathogens that threaten them

Monitoring the December 2015 summit eruptions of Mt. Etna (Italy): Implications on eruptive dynamics

A lengthy period of eruptive activity fromthe summit craters ofMt. Etna started in January 2011. It culminated in early December 2015 with a spectacular sequence of intense eruptive events involving all four summit craters (Voragine, Bocca Nuova,NewSoutheast Crater, and Northeast Crater). The activity consisted of high eruption columns, Strombolian explosions, lava flows andwidespread ash falls that repeatedly interferedwith air traffic. The most powerful episode occurred on 3 December 2015 from the Voragine. After three further potent episodes fromthe Voragine, activity shifted to the NewSoutheast Crater on 6 December 2015, where Strombolian activity and lava flow emission lasted for two days and were fed by the most primitive magma of the study period. Activity once more shifted to the Northeast Crater, where ash emission and weak Strombolian activity took place for several days. Sporadic ash emissions from all craters continued until 18 December, when all activity ceased. Although resembling the summit eruptions of 1998–1999, which also involved all four summit craters, thismultifaceted eruptive sequence occurred in an exceptionally short time window of less than three days, unprecedented in the recent activity of Mt. Etna. It also produced important morphostructural changes of the summit area with the coalescence of Voragine and Bocca Nuova in a single large crater, the “Central Crater”, reproducing themorphological setting of the summit cone before the formation of Bocca Nuova in 1968. The December 2015 volcanic crisis was followed closely by the staff of the Etna Observatory to monitor the on-going activity and forecast its evolution, in accordance with protocols agreed with the Italian Civil Protection Department.Published53-695V. Dinamica dei processi eruttivi e post-eruttiviJCR Journa

Cultures in Mountain Areas / Culture in aree di montagna / Kulturen in Gebirgsregionen

Comparative studies of mountain areas have long been at the core of the discussion about the relations between nature and culture as well as on environmental and social change. This volume searches for ways to develop further critical comparative perspectives in the study of cultures in mountain areas by drawing inter- and transdisciplinary links amongst anthropology, geography, folklore studies, montology, and global history. Drawing on examples mostly from the Alps and the Andes, but also extending to the global mountains, the authors explore socioecological environments, historical and political processes, borderscapes, demographic dynamics, forms of domestic organization, rituals, religiosities, and human-non-humanrelations.Gli studi comparativi sulle aree montane sono da tempo al centro del dibattito sul rapporto tra natura e cultura e sui cambiamenti ecologici e sociali. Questo volume è alla ricerca di nuovi percorsi per sviluppare ulteriormente prospettive comparative critiche per lo studio delle culture delle aree montane, tracciando collegamenti inter- e transdisciplinari tra antropologia, geografia, studi di folklore, montologia e storia globale. Basandosi su esempi provenienti soprattutto dalle Alpi e dalle Ande, ma estendendo l’orizzonte anche ad altre regioni montane a livello globale, le autrici e gli autori esplorano ambienti socio-ecologici, processi storici e politici, paesaggi di confine, dinamiche demografiche, forme di organizzazione domestica, rituali, religiosità e relazioni tra umani e non-umani.Vergleichende Studien über Bergregionen stehen seit langem im Zentrum der Debatte über das Verhältnis zwischen Natur und Kultur sowie über den ökologischen und sozialen Wandel. Dieser Band sucht nach Wegen, kritische vergleichende Perspektiven in der Erforschung von Kulturen in Bergregionen weiterzuentwickeln, indem er inter- und transdisziplinäre Verbindungen zwischen Anthropologie, Geographie, Volkskunde, Montologie und (Welt-)Geschichte herstellt. Anhand von Beispielen vor allem aus den Alpen und den Anden, aber auch aus anderen Gebirgsregionen der Welt, untersuchen die Autor:innen sozioökologische Umwelten, historische und politische Prozesse, Grenzlandschaften, demografische Dynamiken, Formen der häuslichen Organisation, Rituale, Religiosität und Mensch-/Nicht-Mensch-Beziehungen