774 resultados para peer-to-peer (P2P) computing


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The eradication of BVD in the UK is technically possible but appears to be socially untenable. The following study explored farmer attitudes to BVD control schemes in relation to advice networks and information sharing, shared aims and goals, motivation and benefits of membership, notions of BVD as a priority disease and attitudes toward regulation. Two concepts from the organisational management literature framed the study: citizenship behaviour where actions of individuals support the collective good (but are not explicitly recognised as such) and peer to peer monitoring (where individuals evaluate other’s behaviour). Farmers from two BVD control schemes in the UK participated in the study: Orkney Livestock Association BVD Eradication Scheme and Norfolk and Suffolk Cattle Breeders Association BVD Eradication Scheme. In total 162 farmers participated in the research (109 in-scheme and 53 out of scheme). The findings revealed that group helping and information sharing among scheme members was low with a positive BVD status subject to social censure. Peer monitoring in the form of gossip with regard to the animal health status of other farms was high. Interestingly, farmers across both schemes supported greater regulation with regard to animal health, largely due to the mistrust of fellow farmers following voluntary disease control measures. While group cohesiveness varied across the two schemes, without continued financial inducements, longer-term sustainability is questionable

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The perils of peer review come home to roost in academe.

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Program directors and department chairs require different means of assessing faculty quality due to the unreliability of student course evaluation data. This report outlines alternative strategies for review committees to assess faculty instructional quality. This report also details incorporation of annual performance reviews for tenure-track faculty into tenure decisions.

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Previous works have studied the characteristics and peculiarities of P2P networks, especially security information aspects. Most works, in some way, deal with the sharing of resources and, in particular, the storage of files. This work complements previous studies and adds new definitions relating to this kind of systems. A system for safe storage of files (SAS-P2P) was specified and built, based on P2P technology, using the JXTA platform. This system uses standard X.509 and PKCS # 12 digital certificates, issued and managed by a public key infrastructure, which was also specified and developed based on P2P technology (PKIX-P2P). The information is stored in a special file with XML format which is especially prepared, facilitating handling and interoperability among applications. The intention of developing the SAS-P2P system was to offer a complementary service for Giga Natal network users, through which the participants in this network can collaboratively build a shared storage area, with important security features such as availability, confidentiality, authenticity and fault tolerance. Besides the specification, development of prototypes and testing of the SAS-P2P system, tests of the PKIX-P2P Manager module were also performed, in order to determine its fault tolerance and the effective calculation of the reputation of the certifying authorities participating in the system

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This paper presents the work in progress of an on-demand software deployment system based on application virtualization concepts which eliminates the need of software installation and configuration on each computer. Some mechanisms were created, such as mapping of utilization of resources by the application to improve the software distribution and startup; a virtualization middleware which give all resources needed for the software execution; an asynchronous P2P transport used to optimizing distribution on the network; and off-line support where the user can execute the application even when the server is not available or when is out of the network. © Springer-Verlag Berlin Heidelberg 2010.

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In the past few years, vehicular ad hoc networks(VANETs) was studied extensively by researchers. VANETs is a type of P2P network, though it has some distinct characters (fast moving, short lived connection etc.). In this paper, we present several limitations of current trust management schemes in VANETs and propose ways to counter them. We first review several trust management techniques in VANETs and argue that the ephemeral nature of VANETs render them useless in practical situations. We identify that the problem of information cascading and oversampling, which commonly arise in social networks, also adversely affects trust management schemes in VANETs. To the best of our knowledge, we are the first to introduce information cascading and oversampling to VANETs. We show that simple voting for decision making leads to oversampling and gives incorrect results in VANETs. To overcome this problem, we propose a novel voting scheme. In our scheme, each vehicle has different voting weight according to its distance from the event. The vehicle which is more closer to the event possesses higher weight. Simulations show that our proposed algorithm performs better than simple voting, increasing the correctness of voting. © 2012 Springer Science + Business Media, LLC.

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[EN]Introduction to Content Language and Integrated Learning ( CLIL) is a 60 hour on line course offered by Universidad de Las Palmas de Gran Canaria within its extracurricular courses. During three years we have had 76 students whose final assessment has been to create a CLIL lesson which was evaluated by their peers. The tool for the peer assessment has been the Moodle platform; forums. The assessment was guided by a list of questions they had to apply when evaluating the lessons, but the replies from the CLIL lesson creators did not have any predetermined structure or guidelines to be followed. We have analysed the assessments and replies by grouping them according to content similarities.

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Being able to positively interact and build relationships with playmates in preschool years is crucial to achieve positive adjustment. An update review and two studies on such topics were provided. Study 1 is observational; it investigates the type of social experience in groups (N = 443) of children (N = 120) at preschool age in child-led vs. teacher-led contexts. The results revealed that in child-led contexts children were more likely to be alone, in dyads, and in small peer groups; groups were mostly characterized by same-gender playmates who engaged in joint interactions, with few social interactions with teachers. In teacher-led contexts, on the other hand, children were more likely to be involved in small, medium and large groups; groups were mostly characterized by other-gender playmates, involved in parallel interactions, with teachers playing a more active role. The purpose of Study 2 was to describe the development of socio-emotional competence, temperamental traits and linguistic skill. It examined the role of children’s reciprocated nominations (=RNs) with peers, assessed via sociometric interview, in relation to socio-emotional competence, temperamental traits and linguistic skill. Finally, the similarity-homophily tendency was investigated. Socio-emotional competence and temperamental traits were assessed via teacher ratings, linguistic skill via test administration. Eighty-four preschool children (M age = 62.53) were recruited within 4 preschool settings. Those children were quite representative of preschool population. The results revealed that children with higher RNs showed higher social competence (tendency), social orientation, positive emotionality, motor activity and linguistic skill. They exhibited lower anxiety-withdrawal. The results also showed that children prefer playmates with similar features: social competence, anger-aggression (tendency), social orientation, positive emotionality, inhibition to innovation, attention, motor activity (tendency) and linguistic skill. Implications for future research were suggested.

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Il video streaming in peer-to-peer sta diventando sempre più popolare e utiliz- zato. Per tali applicazioni i criteri di misurazione delle performance sono: - startup delay: il tempo che intercorre tra la connessione e l’inizio della ripro- duzione dello stream (chiamato anche switching delay), - playback delay: il tempo che intercorre tra l’invio da parte della sorgente e la riproduzione dello stream da parte di un peer, - time lag: la differenza tra i playback delay di due diversi peer. Tuttavia, al giorno d’oggi i sistemi P2P per il video streaming sono interessati da considerevoli ritardi, sia nella fase di startup che in quella di riproduzione. Un recente studio su un famoso sistema P2P per lo streaming, ha mostrato che solitamente i ritardi variano tra i 10 e i 60 secondi. Gli autori hanno osservato anche che in alcuni casi i ritardi superano i 4 minuti! Si tratta quindi di gravi inconvenienti se si vuole assistere a eventi in diretta o se si vuole fruire di applicazioni interattive. Alcuni studi hanno mostrato che questi ritardi sono la conseguenza della natura non strutturata di molti sistemi P2P. Ogni stream viene suddiviso in blocchi che vengono scambiati tra i peer. A causa della diffusione non strutturata del contenuto, i peer devono continuamente scambiare informazioni con i loro vicini prima di poter inoltrare i blocchi ricevuti. Queste soluzioni sono estremamente re- sistenti ai cambiamenti della rete, ma comportano una perdita notevole in termini di prestazioni, rendendo complicato raggiungere l’obiettivo di un broadcast in realtime. In questo progetto abbiamo lavorato su un sistema P2P strutturato per il video streaming che ha mostrato di poter offrire ottimi risultati con ritardi molto vicini a quelli ottimali. In un sistema P2P strutturato ogni peer conosce esattamente quale blocchi inviare e a quali peer. Siccome il numero di peer che compongono il sistema potrebbe essere elevato, ogni peer dovrebbe operare possedendo solo una conoscenza limitata dello stato del sistema. Inoltre il sistema è in grado di gestire arrivi e partenze, anche raggruppati, richiedendo una riorganizzazione limitata della struttura. Infine, in questo progetto abbiamo progettato e implementato una soluzione personalizzata per rilevare e sostituire i peer non più in grado di cooperare. Anche per questo aspetto, l’obiettivo è stato quello di minimizzare il numero di informazioni scambiate tra peer.

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Obbiettivo: Valutazione delle eventuali differenze nel trattamento ortodontico di un gruppo di bambini con particolari necessità sanitarie (SHCN) rispetto ad un gruppo di bambini non diagnosticati con SHCN. Materiali e Metodi: Il gruppo campione (SHCN) è costituito da 50 bambini con SHCN. Il gruppo di controllo (NO SHCN) è costituito da 50 bambini non diagnosticati con SHCN pienamente corrispondenti per età, genere e tipo di apparecchio ortodontico utilizzato con i pazienti del gruppo di studio. I dati riguardanti i gruppi SHCN e NO SHCN sono stati analizzati in modo retrospettivo, valutando: - il punteggio pre- e post-trattamento e la riduzione finale dei valori dell'indice PAR (Peer Assessment Rating), della componente DHC (Dental Health Component) e della componente AC (Aesthetic Component) dell'indice IOTN (Orthodontic Treatment Need Index), - il numero di appuntamenti, - il numero di sedute semplici e complesse, - la durata complessiva del trattamento, - l'età all’inizio ed alla fine della terapia. Risultati: Non sono state rilevate differenze statisticamente significative tra i due gruppi per quanto concerne il numero di appuntamenti, la durata complessiva del trattamento, l'età all’inizio ed alla fine della terapia ortodontica (valori del p-value:0.682, 0.458, 0.535, 0.675). Sono state rilevate differenze statisticamente significative tra i due gruppi per quanto riguarda i punteggi dell’indice PAR, delle componenti DHC e AC dello IOTN pre- e post-trattamento, il numero di sedute semplici e complesse (valori del p-value:0.030, 0.000, 0.020, 0.023, 0.000, 0.000, 0.043, 0.037). Per quanto concerne la riduzione finale del valore dell’indice PAR, della componente DHC e di quella AC dello IOTN non sono state riscontrate differenze statisticamente significative tra i due gruppi (valori del p-value:0.060, 0.765, 0.825). Conclusioni: Lo studio incoraggia gli ortodontisti a trattare i bambini con SHCN nell'obiettivo di migliorarne la qualità di vita, pur evidenziando la necessità di un maggior numero di sedute complesse.

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Publishing is an essential means of validation and communication of research. This is no different in transdisciplinary research, where publishing also aims at contributing to the development of society through sharing of knowledge. In the scientific world, authors need to disseminate and validate results, reflect on issues, and participate in debates. On the other hand, institutions and individuals are assessed according to their publication record – as probably the most influential of all current evaluation criteria. Occupying the space between article production and counting impact factors, journal editors and reviewers play an important role in defining and using rules to assess and improve the work submitted to them. Publishing transdisciplinary research poses specific challenges, in particular with regard to peer-review processes, as it addresses different knowledge communities with different value systems and purposes.

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This study examined the influence of single peer to peer interventions on participants' recovery attitudes.

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This study examines the influence of recovery-oriented peer events on participants' recovery attitudes and explores who benefits most from such events. Changes in participants' recovery attitudes were evaluated (pre, post, follow-up), and compared with changes of control groups. Distributions of recovery-related values in subgroups were analyzed descriptively. The results of non-parametric tests (Friedman) showed participants with significantly higher values in the dimension Recovery is possible directly after the interventions (P = 0.006), but not 6 months later, and not in comparison with members of control groups. On a descriptive level, women, participants with schizophrenia and with two or more episodes of the disorder showed higher recovery-related values compared to men, participants with an affective disorder and only one episode. Within their feedback, organizations and peers express a positive view of peer support, but evidence for a positive impact of the evaluated peer events on recovery attitude is limited.