745 research outputs found

    Towards the Coevolution of Incentives in BitTorrent

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    BitTorrent is a peer-to-peer file sharing system that is open to variant behavior at the peer level through modification of the client software. A number of different variants have been released and proposed. Some are successful and become widely used whereas others remain in a small minority or are not used at all. In previous work we explored the performance of a large set of client variants over a number of dimensions by applying Axelrod’s round-robin pairwise tournament approach. However, this approach does not capture the dynamics of client change over time within pairwise tournaments. In this work we extend the tournament approach to include a limited evolutionary step, within the pairwise tournaments, in which peers copy their opponents strategy (client variant) if it outperforms their own and also spontaneously change to the opponents strategy with a low mutation probability. We apply a number of different evolutionary algorithms and compare them with the previous non-evolutionary tournament results. We find that in most cases cooperative (sharing) strategies outperformed free riding strategies. These results are comparable to those previously obtained using the round-robin approach without evolution. We selected this limited form of evolution as a step towards understanding the full coevolutionary dynamics that would result from evolution between a large space of client variants in a shared population rather than just pairs of variants. We conclude with a discussion on how such future work might proceed. © 2015, Budapest Tech Polytechnical Institution. All rights reserved

    Friends for Free: Self-Organizing Artificial Social Networks for Trust and Cooperation

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    By harvesting friendship networks from e-mail contacts or instant message "buddy lists" Peer-to-Peer (P2P) applications can improve performance in low trust environments such as the Internet. However, natural social networks are not always suitable, reliable or available. We propose an algorithm (SLACER) that allows peer nodes to create and manage their own friendship networks. We evaluate performance using a canonical test application, requiring cooperation between peers for socially optimal outcomes. The Artificial Social Networks (ASN) produced are connected, cooperative and robust - possessing many of the disable properties of human friendship networks such as trust between friends (directly linked peers) and short paths linking everyone via a chain of friends. In addition to new application possibilities, SLACER could supply ASN to P2P applications that currently depend on human social networks thus transforming them into fully autonomous, self-managing systems

    Hotspots: Modelling capacity for vector-borne disease risk analysis in New Zealand: A case study of Ochlerotatus camptorhynchus incursions in New Zealand

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    This Hotspots case study of Oc. camptorhynchus in New Zealand forms part of the wider aims and objectives of the Hotspots project. The overall aims of the case study were: 1. To evaluate the performance of the Hotspots model as a risk analysis tool for Oc. camptorhynchus; 2. To use and learn from the experience of the various incursions of Oc. camptorhynchus in order to critically assess and improve the model; 3. To gain experience in using the model for risk analysis for Oc. camptorhynchus in particular, and in so doing, also develop experience applicable to risk analysis for other vectors of concern (Table 1); and, 4. To develop an experience and knowledge base as well as guidelines for future use of the model in its various applications related to biosecurity, surveillance and risk assessment and management

    Hotspots: Exotic mosquito risk profiles for New Zealand

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    This document reports the main findings of the first systematic, spatial analyses of risks to New Zealand associated with exotic mosquitoes of current public health concern

    Indexing Archival Films: Alaska Archival Motion Picture Program

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    Since the turn of the twentieth century, the state of Alaska has attracted professional and amateur filmmakers eager to document the northern wilderness and its inhabitants. Existing films on Alaska include thousands of feet of historically precious, unedited footage as well as studio productions; they are in demand by research specialists, educators, and filmmakers, as well as nonprofessional Alaskan citizens. Responding to that demand, administrators of the Rasmuson Library at the University of Alaska in Fairbanks launched the Alaska Archival Motion Picture Program to preserve film footage on Alaska and the circumpolar regions and to make it available to a variety of user groups

    Student Success: A Literature Review of Faculty to Student Mentoring

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    This review summarizes the literature on university faculty to student mentoring programs. There has been a proliferation of mentoring programs because of the perceived benefit to student persistence and retention. While mentoring programs have become common, the research on these programs has not kept pace. Shortcomings identified thirty years ago such as lack of theoretical guidance, lack of operational definition of mentoring, and poor design continue to plague mentoring research. Recommendations to address these shortcomings and improve internal and external validity are examined. As universities continue to have increasingly constrained resources, and pressure to demonstrate strategies to help students be successful, evidence-based research will be increasingly desired. If shortcomings in mentoring research can be addressed, mentoring programs hold the potential to be part of a university’s strategic plan to help students be successful
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