An Experimental Study on Peer Selection in a P2P Network over PlanetLab

Peer-reviewed

Privacy-Aware Peer-to- Peer Content Distribution Using Automatically Recombined Fingerprints

Peer-reviewed

Security, Privacy and Anonymity in Legal Distribution of Copyrighted Multimedia Content over Peer-to-Peer Networks: A Brief Overview

Peer-reviewed

Secure and Anonymous Multimedia Content Distribution in Peer-to-Peer Networks

Peer-reviewed

Software Security Vulnerabilities in Mobile Peer-to-peer Environment

Increase of computational power and emergence of new computer technologies led to popularity of local communications between personal trusted devices. By-turn, it led to emergence of security problems related to user data utilized in such communications. One of the main aspects of the data security assurance is security of software operating on mobile devices. The aim of this work was to analyze security threats to PeerHood, software intended for performing personal communications between mobile devices regardless of underlying network technologies. To reach this goal, risk-based software security testing was performed. The results of the testing showed that the project has several security vulnerabilities. So PeerHood cannot be considered as a secure software. The analysis made in the work is the first step towards the further implementation of PeerHood security mechanisms, as well as taking into account security in the development process of this project.

Design and implementation of a peer-to-peer client for device management

The aim of this master’s thesis was to specify a system requiring minimal configuration and providing maximal connectivity in the vein of Skype but for device management purposes. As peer-to-peer applications are pervasive and especially as Skype is known to provide this functionality, the research was focused on these technologies. The resulting specification was a hybrid of a tiered hierarchical network structure and a Kademlia based DHT. A prototype was produced as a proof-of-concept for the hierarchical topology, demonstrating that the specification was feasible.

Online peer to peer lending: clustering borrowers using self-organizing maps

The purpose of this thesis is to find out whether all the peer to peer lenders are unworthy of credit and also if there are single qualities or combinations of qualities that determine the probability of default of a person or group of people. Distinguishing qualities are searched with self-organizing maps (SOM). Qualities and groups of people found by the self-organizing map are then compared to the average. The comparison is carried out by looking how big proportion of borrowers meeting the criteria is two months or more behind with their payments. Research data used is collected by an Estonian peer to peer lending company during the years of 2011-2014. Data consists of peer to peer borrowers and information gathered from them.

Individual learner, peer group and teacher roles in fostering autonomous language-learning behaviour

Julkaisumaa: Bulgaria

Expression of CD40 ligand, interferon-gamma and Fas ligand genes in endomyocardial biopsies of human cardiac allografts: correlation with acute rejection

The purpose of the present study was to investigate the expression (mRNA) of CD40 ligand (CD40L), interferon-gamma (IFN-gamma) and Fas ligand (FasL) genes in human cardiac allografts in relation to the occurrence of acute cardiac allograft rejection as well as its possible value in predicting acute rejection. The mRNA levels were determined by a semiquantitative reverse transcriptase-polymerase chain reaction method in 39 samples of endomyocardial biopsies obtained from 10 adult cardiac transplant recipients within the first six months after transplantation. Biopsies with ongoing acute rejection showed significantly higher CD40L, IFN-gamma and FasL mRNA expression than biopsies without rejection. The median values of mRNA expression in biopsies with and without rejection were 0.116 and zero for CD40L (P<0.003), 0.080 and zero for IFN-gamma (P<0.0009), and 0.156 and zero for FasL (P<0.002), respectively. In addition, the levels of IFN-gamma mRNA were significantly increased 7 to 15 days before the appearance of histological evidence of rejection (median of 0.086 in pre-rejection biopsies), i.e., they presented a predictive value. This study provides further evidence of heightened expression of immune activation genes during rejection and shows that some of these markers may present predictive value for the occurrence of acute rejection.

The role of CD8+ T cells during allograft rejection

Organ transplantation can be considered as replacement therapy for patients with end-stage organ failure. The percent of one-year allograft survival has increased due, among other factors, to a better understanding of the rejection process and new immunosuppressive drugs. Immunosuppressive therapy used in transplantation prevents activation and proliferation of alloreactive T lymphocytes, although not fully preventing chronic rejection. Recognition by recipient T cells of alloantigens expressed by donor tissues initiates immune destruction of allogeneic transplants. However, there is controversy concerning the relative contribution of CD4+ and CD8+ T cells to allograft rejection. Some animal models indicate that there is an absolute requirement for CD4+ T cells in allogeneic rejection, whereas in others CD4-depleted mice reject certain types of allografts. Moreover, there is evidence that CD8+ T cells are more resistant to immunotherapy and tolerance induction protocols. An intense focal infiltration of mainly CD8+CTLA4+ T lymphocytes during kidney rejection has been described in patients. This suggests that CD8+ T cells could escape from immunosuppression and participate in the rejection process. Our group is primarily interested in the immune mechanisms involved in allograft rejection. Thus, we believe that a better understanding of the role of CD8+ T cells in allograft rejection could indicate new targets for immunotherapy in transplantation. Therefore, the objective of the present review was to focus on the role of the CD8+ T cell population in the rejection of allogeneic tissue.

The Rejection of Prioritarianism

Since the late 1990’s, a group of moral doctrines called prioritarianism has received a lot of interest from many moral philosophers. Many contemporary moral philosophers are attracted to prioritarianism to such an extent that they can be called prioritarians. In this book, however, I reject prioritarianism, including not only “pure” prioritarianism but also hybrid prioritarian views which mix one or more non-prioritarian elements with prioritarianism. This book largely revolves around certain problems and complications of prioritarianism and its particular forms. Those problems and complications are connected to risk, impartiality, the arbitrariness of prioritarian weightings and possible future individuals. On the one hand, I challenge prioritarianism through targeted objections to various specific forms of prioritarianism. All those targeted objections are connected to risk or possible future individuals. It seems to me that together they give good grounds for believing that prioritarianism is not the way to go. On the other hand, I challenge prioritarianism by pointing out and discussing certain general problems of prioritarianism. Those general problems are connected to impartiality and the arbitrariness of prioritarian weightings. They may give additional grounds for believing that all prioritarian views should be rejected. Prioritarianism can be seen as a type of weighted utilitarianism and thus as an extension of utilitarianism. Utilitarianism is morally ultimately concerned, and morally ultimately concerned only, with some kind of maximization of utility or expected utility. Prioritarianism, on the other hand, is morally ultimately concerned, and morally ultimately concerned only, with some kind of maximization of priority-weighted utility, expected priority-weighted utility or priority-weighted expected utility. Thus prioritarianism, unlike utilitarianism, is a distribution-sensitive moral view. Besides rejecting prioritarianism, I reject also various other distribution-sensitive moral views in this book. However, I do not reject distribution-sensitivity in morality, as I end up endorsing a type of distribution-sensitive hybrid utilitarianism which mixes non-utilitarian elements with utilitarianism.

Induction of oral tolerance and the effect of interleukin-4 on murine skin allograft rejection

We studied the effect of oral and portal vein administration of alloantigens on mouse skin allograft survival. Graft receptor BALB/c mice received spleen cells (30, 90, 150 or 375 x 10(6)) from donor C57BL/6 mice intragastrically on three successive days, starting seven days before the skin graft. Allograft survival was significantly increased with the feeding of 150 x 10(6) allogeneic spleen cells by one gavage (median survival of 12 vs 14 days, P <= 0.005) or when 300 x 10(6) cells were given in six gavage (12 vs 14 days, P < 0.04). A similar effect was observed when 150 x 10(6) spleen cells were injected into the portal vein (12 vs 14 days, P <= 0.03). Furthermore, prolonged allograft survival was observed with subcutaneous (12 vs 16 days, P <= 0.002) or systemic (12 vs 15 days, P <= 0.016) application of murine interleukin-4 (IL-4), alone or in combination with spleen cell injection into the portal vein (12 vs 18 days, P <= 0.0018). Taken together, these results showed that tolerance induction with spleen cells expressing fully incompatible antigens by oral administration or intraportal injection partially down-modulates skin allograft rejection. Furthermore, these findings demonstrated for the first time the effect of subcutaneous or systemic IL-4 application on allograft skin survival suggesting its use as a beneficial support therapy in combination with a tolerance induction protocol.