120 resultados para peer to peer networks


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Taking advantage of the huge potential of consumers’ untapped computing power, self-organizing cloud is a novel computing paradigm where the consumers are able to contribute/sell their computing resources. Meanwhile, host machines held by the consumers are connected by a peer-to-peer (P2P) overlay network on the Internet. In this new architecture, due to large and varying multitudes of resources and prices, it is inefficient and tedious for consumers to select the proper resource manually. Thus, there is a high demand for a scalable and automatic mechanism to accomplish resource allocation. In view of this challenge, this paper proposes two novel economic strategies based on mechanism design. Concretely, we apply the Modified Vickrey Auction (MVA) mechanism to the case where the resource is sufficient; and the Continuous Double Auction (CDA) mechanism is employed when the resource is insufficient. We also prove that aforementioned mechanisms have dominant strategy incentive compatibility. Finally, extensive experiment results are conducted to verify the performance of the proposed strategies in terms of procurement cost and execution efficiency.

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AIM: To describe the support needs of parents caring for a child with an intellectual disability in the first year of life. BACKGROUND: Parents of children with intellectual disabilities face significant challenges during the first year of their child's life which is an important developmental period not previously addressed in the literature. The provision of support by health professionals, particularly nurses and midwives, during this crucial period can impact on parental well-being and on the health and developmental outcomes of their children. However, parents often feel unsupported. DESIGN: The study used a qualitative descriptive methodology. METHODS: Semi-structured interviews were conducted with parents of eleven children with an intellectual disability in Victoria, Australia, during 2014. Interviews were digitally recorded, transcribed verbatim and analysed using thematic data analysis. FINDINGS: Three key areas of support need were identified to assist parents to provide effective care for their child with an intellectual disability in the first year of life: (1) emotional support as parents adjusted to their role of caring for a child with an intellectual disability; (2) information support as they embarked on a quest for knowledge; and (3) support to facilitate their connection to peer networks. The findings highlighted inconsistent provision of support for parents. CONCLUSION: This study informs health professionals about how to provide holistic, timely support to parents of children with intellectual disabilities in the first year of life. There is an urgent need to review how nurses and midwives can provide relevant support that is responsive to parents' needs.

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Mobile users connected to wireless networks expect performance comparable to those on wired networks for interactive multimedia applications. Satisfying Quality of Service (QoS) requirements for such applications in wireless networks is a challenging problem due to limitations of low bandwidth, high error rate and frequent disconnections of wireless channels. In addition, wireless networks suffer from varying bandwidth. In this paper we investigate object prefetching during times of connectedness and bandwidth availability to enhance user perceived connectedness. This paper presents an access model that is suitable for multimedia access in wireless networks. Access modelling for the purpose of predicting future accesses in the context of speculative prefetching has received much attention in the literature. The model recognizes that a web page, instead of just a single file, is typically a compound of several files. When it comes to making prefetch decisions, most previous studies in speculative prefetching resort to simple heuristics, such as prefetching an item with access probabilities larger than a manually tuned threshold. This paper takes a different approach. Specifically, it models the performance of the prefetcher, taking into account access predictions and resource parameters, and develops a prefetch policy based on a theoretical analysis of the model. Since the analysis considers cache as one of the resource parameters, the resulting policy integrates prefetch and cache replacement decisions. The paper investigates the effect of prefetching on network load. In order to make effective use of available resources and maximize access improvement, it is beneficial to prefetch all items with access probabilities exceeding certain threshold.

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Herb Feith came to Australia as a Jewish refugee from Europe as it was on the bring of war in 1939 and went on to become an internationally renowned and passionate scholar of Indonesia. He died tragically in Melbourne in 2001. This engaging biography tells his own extraordinary story and traces his interest in Indonesia, his determination to establish networks of serious study of Indonesia and Southeast Asia and his commitment to peace activism.

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Background: Little is known about what support the United Kingdom (UK) armed forces require when they return from operations. Aims: To investigate the perceived psychological support requirements for service personnel on peacekeeping deployments when they return home from operations and examine their views on the requirement for formal psychological debriefings. Methods: A retrospective cohort study examined the perceived psychological needs of 1202 UK peacekeepers on return from deployment. Participants were sent a questionnaire asking about their perceived needs relating to peacekeeping deployments from April 1991 to October 2000. Results: Results indicate that about two-thirds of peacekeepers spoke about their experiences. Most turned to informal networks, such as peers and family members, for support. Those who were highly distressed reported talking to medical and welfare services. Overall, speaking about experiences was associated with less psychological distress. Additionally, two thirds of the sample was in favour of a formalised psychological debriefing on return to the UK. Conclusions: This study suggests that most peacekeepers do not require formalised interventions on homecoming and that more distressed personnel are already accessing formalised support mechanisms. Additionally social support from peers and family appears useful and the UK military should foster all appropriate possibilities for such support. Declaration of Interest: The Stage 1 study was funded by the US Department of Defence (DoD) and the follow up study by the Medical Research Counsel (MRC). Neither the DoD nor MRC had any input into the design, conduct, analysis or reporting of the study. The views expressed are not those of any US or UK governmental organisation. We thank Mr Nick Blatchley of MOD for help in identifying the cohorts.

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Group extension methods are widely recognized as the most effective extension method in agricultural development internationally. Research in this area tends to look at group function, and factors that inhibit or promote successful group activity. Most development projects start with an analysis of whether groups exist or may need to be formed, and then focus on group function. However, very little research to date has considered the farmer group from a whole community context, when assessing knowledge and information dissemination in rural areas. This paper presents and discusses research finding from a case study with three communities in Gulu district of Northern Uganda, where household surveys were used to map networks within andbetween community members and external organizations identified as promoting agricultural development in the region. The potential impact of inclusion or exclusion in such a group within small communities emerged as a significant issue, as well as the strong disconnect between community and external organizational perceptions of group existence, function and impact.

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The telecommunication industry is entering a new era. The increased traffic demands imposed by the huge number of always-on connections require a quantum leap in the field of enabling techniques. Furthermore, subscribers expect ever increasing quality of experience with its joys and wonders, while network operators and service providers aim for cost-efficient networks. These requirements require a revolutionary change in the telecommunications industry, as shown by the success of virtualization in the IT industry, which is now driving the deployment and expansion of cloud computing. Telecommunications providers are currently rethinking their network architecture from one consisting of a multitude of black boxes with specialized network hardware and software to a new architecture consisting of “white box” hardware running a multitude of specialized network software. This network software may be data plane software providing network functions virtualization (NVF) or control plane software providing centralized network management — software defined networking (SDN). It is expected that these architectural changes will permeate networks as wide ranging in size as the Internet core networks, to metro networks, to enterprise networks and as wide ranging in functionality as converged packet-optical networks, to wireless core networks, to wireless radio access networks.

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This article reflects findings from a long term case study of an online community of practice established through a network for the professional education of teachers in Ontario, Canada. The Education Network of Ontario/Réseau éducatif de l'Ontario (ENO/REO) was created in 1992–1993 to support and connect teachers from kindergarten to grade 12 in the province of Ontario. Its mandate was to ensure that all teachers had free access to the Internet and to each other and to encourage the development of skills in the area of information and communication technology with the ultimate goal of using those skills to improve classroom practice. The study investigated whether information technology had the potential to connect teachers to each other in order to build the capacity to create networks where professional learning could take place in a cost-efficient and flexible time and/or place. It was found that participants were early adopters who enjoyed innovation, that online networkswere supportive for learning but hard to maintain over time, and though they supported the integration of technology in the classroom, other barriers within schools could challenge this effect.

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The peer-to-peer content distribution network (PCDN) is a hot topic recently, and it has a huge potential for massive data intensive applications on the Internet. One of the challenges in PCDN is routing for data sources and data deliveries. In this paper, we studied a type of network model which is formed by dynamic autonomy area, structured source servers and proxy servers. Based on this network model, we proposed a number of algorithms to address the routing and data delivery issues. According to the highly dynamics of the autonomy area, we established dynamic tree structure proliferation system routing, proxy routing and resource searching algorithms. The simulations results showed that the performance of the proposed network model and the algorithms are stable.

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When older people enter residential care facilities, disruption to social networks may occur, with detrimental effects on health and wellbeing. This article reports on a study undertaken in an aged care facility in Melbourne, Australia, that explored the potential for a visiting companion animal programme to improve the health and wellbeing of residents and to promote their capacity for building relationships. Results back assertions in the literature that companion animals foster relationships by giving people opportunities to interact with others, but further study is needed to verify the link

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Background : General Practitioners and community nurses rely on easily accessible, evidence-based online information to guide practice. To date, the methods that underpin the scoping of user-identified online information needs in palliative care have remained under-explored. This paper describes the benefits and challenges of a collaborative approach involving users and experts that informed the first stage of the development of a palliative care website.

Method : The action research-inspired methodology included a panel assessment of an existing palliative care website based in Victoria, Australia; a pre-development survey (n = 197) scoping potential audiences and palliative care information needs; working parties conducting a needs analysis about necessary information content for a redeveloped website targeting health professionals and caregivers/patients; an iterative evaluation process involving users and experts; as well as a final evaluation survey (n = 166).

Results : Involving users in the identification of content and links for a palliative care website is time-consuming and requires initial resources, strong networking skills and commitment. However, user participation provided crucial information that led to the widened the scope of the website audience and guided the development and testing of the website. The needs analysis underpinning the project suggests that palliative care peak bodies need to address three distinct audiences (clinicians, allied health professionals as well as patients and their caregivers).

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Web developers should pay close attention to the content, language, and accessibility needs of these groups. Given the substantial cost associated with the maintenance of authoritative health information sites, the paper proposes a more collaborative development in which users can be engaged in the definition of content to ensure relevance and responsiveness, and to eliminate unnecessary detail. Access to volunteer networks forms an integral part of such an approach.

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Grid Web Services are still relevantly a new to business systems, and as more systems are being attached to it, any threat to it could bring collapse and huge harm. Some of these potential threats to Grid Web services come in a new form of a new denial of service attack (DoS), called XML Denial of Service or XDOS attacks. Though, as yet, there have not been any reported attacks from the media, we have observed these attacks are actually far less complex to implement than any previous Denial of Service (DoS), but still just as affective. Current security applications for grid web services (WS-Security for example), based on our observations, and are not up to job of handling the problem. In this paper, we build on our previous work called Service Oriented Traceback Architecture (SOTA), and apply our model to Grid Networks that employ web services. We further introduce a filter defence system, called XDetector, to work in combination with SOTA. Our results show that SOTA in conjunction with XDetector makes for an effective defence against XDoS attacks and upcoming DXDoS.

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The aim of this research is to understand how stakeholder interactions can facilitate the patient flow process within a hospital. An analysis of the findings reveals that nurses are in a perfect position to be a conduit between doctors and managers. This is due to several factors including the nurses understanding of both the clinical and control worlds, as well as nurses ability to form networks based on their pivotal characteristics. As a result of these findings, a model for better understanding stakeholder relationships is developed. In this research, a mixed methods approach was used by undertaking a cultural assessment via survey questionnaire, complemented by observations of interactions between organisational actors, including formal semi-structured interviews and reflections of many hours of observation. Glouberman and Mintzberg’s four world’s models is used as a foundation for the arguments of this paper. Mitchell, Agle and Wood’s (1997) model is used to discuss the three stakeholder groups of this research including doctors, nurses, and managers.

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Various attempts have been made to minimise energy consumption of rail vehicles by means of regenerative power from electric braking of traction motors. This paper describes energy efficiency methods in electrified railways based on recovery of energy. Direct recovery methods that return regenerative power to electrified networks, and recovery methods based on energy storage systems are elaborated. The benefits of developing recovery methods and advantages of energy storage systems are discussed.

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Online communications, multimedia, mobile computing and face-to-face learning create blended learning environments to which some Virtual Design Studios (VDS) have reacted to. Social Networks (SN), as instruments for communication, have provided a potentially fruitful operative base for VDS. These technologies transfer communication, leadership, democratic interaction, teamwork, social engagement and responsibility away from the design tutors to the participants. The implementation of Social Network VDS (SNVDS) moved the VDS beyond its conventional realm and enabled students to develop architectural design that is embedded into a community of learners and expertise both online and offline. Problem-based learning (PBL) becomes an iterative and reflexive process facilitating deep learning. The paper discusses details of the SNVDS, its pedagogical implications to PBL, and presents how the SNVDS is successful in enabling architectural students to collaborate and communicate design proposals that integrate a variety of skills, deep learning, knowledge and construction with a rich learning experience.