A New Stable Peer-to-Peer Protocol with Non-persistent Peers

Recent studies have suggested that the stability of peer-to-peer networks may rely on persistent peers, who dwell on the network after they obtain the entire file. In the absence of such peers, one piece becomes extremely rare in the network, which leads to instability. Technological developments, however, are poised to reduce the incidence of persistent peers, giving rise to a need for a protocol that guarantees stability with non-persistent peers. We propose a novel peer-to-peer protocol, the group suppression protocol, to ensure the stability of peer-to-peer networks under the scenario that all the peers adopt non-persistent behavior. Using a suitable Lyapunov potential function, the group suppression protocol is proven to be stable when the file is broken into two pieces, and detailed experiments demonstrate the stability of the protocol for arbitrary number of pieces. We define and simulate a decentralized version of this protocol for practical applications. Straightforward incorporation of the group suppression protocol into BitTorrent while retaining most of BitTorrent's core mechanisms is also presented. Subsequent simulations show that under certain assumptions, BitTorrent with the official protocol cannot escape from the missing piece syndrome, but BitTorrent with group suppression does.Comment: There are only a couple of minor changes in this version. Simulation tool is specified this time. Some repetitive figures are remove

ON THE RELIABILITY AND EFFICIENCY OF INFORMATION TRANSMISSION SYSTEMS

174 pagesWe make notable advances on the reliability and efficiency of several different information transmission systems by providing theoretical results supported by numerical evaluations. A known stability issue in peer-to-peer networks and our solution in the form of a new peer-to-peer protocol take the center stage in the first part of this dissertation. The second part of the dissertation focuses on finding the best possible efficiency for given reliability levels in a couple of multiple-encoder and one-decoder multiterminal source-coding information transmission systems. In the language of information theory, this reads as finding the rate region for a given set of distortions on the sources to be reconstructed at the central decoder. Recent studies have suggested that the stability of peer-to-peer networks may rely on persistent peers, who dwell on the network after they obtain the entire file. It has been proven that if peers depart the peer-to-peer network immediately after they complete the pieces of the file of interest, then one piece becomes extremely rare in the network, which leads to instability. Technological developments, however, are poised to reduce the incidence of persistent peers, giving rise to a need for a protocol that guarantees stability with non-persistent peers. We propose a novel peer-to-peer protocol, the group suppression protocol, to ensure the stability of peer-to-peer networks under the scenario that all the peers adopt non-persistent behavior. Using a suitable Lyapunov potential function, the group suppression protocol is proven to be stable when the file is broken into two pieces, and detailed experiments demonstrate the stability of the protocol for arbitrary number of pieces. We define and simulate a decentralized version of this protocol for practical applications. Straightforward incorporation of the group suppression protocol into BitTorrent while retaining most of BitTorrent's core mechanisms is also presented. Subsequent simulations show that under certain assumptions, BitTorrent with the official protocol cannot escape from the missing piece syndrome, but BitTorrent with group suppression does. We start the second part of the dissertation by revisiting the quadratic Gaussian two-encoder source-coding problem, for which a Gaussian quantize-and-bin scheme, also known as the Berger-Tung scheme, is known to achieve the entire rate region. We present a new proof of the impossibility half of the rate-region optimality result that is arguably more direct. Next, we consider the quadratic Gaussian one-help-two source-coding problem with Markovity, in which three encoders separately encode the components of a memoryless vector-Gaussian source that form a Markov chain and the central decoder aims to reproduce the first and the second components in the chain subject to individual distortion constraints. For this problem, we determine that the Gaussian quantize-and-bin scheme achieves the rate region if the distortion on the second source is small enough. The proof technique makes heavy use of the approach we first successfully applied to the quadratic Gaussian two-encoder source-coding problem. Finally, we present a method for outer bounding the rate-distortion region of Gaussian distributed compression problems in which the source variables can be embedded in a Gauss-Markov tree. The outer bound so obtained takes the form of a convex optimization problem. Numerical evaluations demonstrate that the outer bound is close to the Berger-Tung inner bound, coinciding with it in many cases

TURF TOE IN A TAEKWANDOO PLAYER: CASE REPORT

Metatarsophalengeal joint injuries of great toe termed as ''turf toe'' can occur in many sportive activities. However, it has not been reported before in taekwondoo players. These injuries may result in significant morbidity. Turf toe injuries, which are mainly treated with conservative methods, occasionally require surgery. In this case report, we present a surgically treated turf toe in a taekwondoo playe

Vitamin D Receptor Gene Polymorphisms in Rheumatoid Arthritis

Objectives: In this study, we investigated the association of BsmI, TaqI, and FokI polymorphisms in the vitamin D receptor gene in rheumatoid arthritis patients with rheumatoid factor positivity and erosive disease of rheumatoid arthritis

Is There Any Correlation Between The Elevated Plasma Levels and Gene Variations of Factor VIII in Turkish Thrombosis Patients?

We investigated factor VIII (FVIII) gene mutations in 20 thrombosis patients with high level of FVIII and 20 control healthy participants. Blood samples were used for the determination of FVIII levels using static timing analyze (STA) kits. Informed consent forms were collected from all participants. Factor VIII level was 237 +/- 46 IU/dL in patients group; however, it was 122 +/- 38 IU/dL in healthy control participants. Isolated genomic DNAs were screened using 37 pairs of primers covering promoter region and 26 exons of FVIII gene. Single-strand conformation analysis (SSCA) technique was performed for polymorphism/mutation analyses. We observed polymorph patterns in exon 6, exon 13, exon 14F, exon 19, and exon 25 regions. However, we found no evidence of an association between observed single nucleotide polymorphisms and high thrombosis levels. In conclusion, observed exons polymorphisms do not seem to be associated with a venous thromboembolism

Is There An Overlap Of Antineutrophil Cytoplasmic Antibody-Associated Vasculitides With Igg4-Related Disease Or Not?

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Evaluation of Peripheral Zone Prostate Cancer Aggressiveness Using the Ratio of Diffusion Tensor Imaging Measures

Purpose. To evaluate the aggressiveness of peripheral zone prostate cancer by correlating the Gleason score (GS) with the ratio of the diffusion tensor imaging (DTI) measures. Materials and Methods. Forty-two peripheral zone prostate tumors were imaged using DTI. Regions of interest focusing on the center of tumor foci and noncancerous tissue were used to extract statistical measures of mean diffusivity (MD) and fractional anisotroy (FA). Measure ratio was calculated by dividing tumor measure by noncancerous tissue measure. Results. Strong correlations are observable between GS and MD measures while weak correlations are present between GS and FA measures. Minimum tumor MD (MDmin) and the ratio of minimum MD (rMDmin) show the same highest correlation with GS (both ρ=-0.73). Between GS ≤ 7 (3 + 4) and GS ≥ 7 (4 + 3), differences are significant for all MD measures but for some FA measures. MD measures perform better than FA measures in discriminating GS ≥ 7 (4 + 3). Conclusion. Ratios of MD measures can be used in evaluation of peripheral zone prostate cancer aggressiveness; however tumor MD measures alone perform similarly

Do ANCA-associated vasculitides and IgG4-related disease really overlap or not?

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and immunoglobulin G4-related disease (IgG4-RD) have some common features. The co-occurrence/concurrence of AAV and IgG4-RD was recently published by the collaborative European Vasculitis Study Group. First, we aimed to investigate ANCA positivity of our IgG4-RD cohort. Second, a literature review of co-occurrence/concurrence of AAV and IgG4-RD was done. Methods: Data of 62 patients with IgG4-RD in Hacettepe Vasculitis Center Database were used. Patient dataset was designed to include demographic data, clinical characteristics, imaging and IgG4-RD, AAV and ANCA test results. At the next step, we performed a systematic literature review in PUBMED database covering the time period from 1976 until April 2018. Relevant publications were searched using these MeSH terms ''IgG4-related disease and Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis'', "IgG4-related disease and Eosinophilic Granulomatosis with Polyangiitis", "IgG4-related disease and Microscopic Polyangiitis" and "IgG4-related disease and Granulomatosis with Polyangiitis". Results: Three (10.3%) of 29 patients had low titer ANCA positivity. These three patients didn't have any findings of vasculitis and no granuloma was seen in biopsy. In the literature review, we found 17 cases had features of both IgG4-RD and AAV. These cases were re-evaluated according to the Comprehensive Diagnostic Criteria for IgG4-RD. ANCA were positive in 15 of 17 patients (88%). Conclusion: None of our IgG4-RD patients overlapped with AAV. Only two patients in the literature review seemed to be fully compatible with both diseases. Even though AAV and IgG4-RD share similar clinical features, we think this might be a co-occurrence instead of a histopathological link.PubMe

Avascular necrosis less frequently found in systemic lupus erythematosus patients with the use of alternate day corticosteroid

Background/aim: Avascular necrosis (AVN) is the death of bone due to compromise of blood flow. The etiology of AVN is multifactorial; corticosteroid usage is the second most significant factor after trauma, and systemic lupus erythematosus (SLE) is the most common underlying disease. The objective of this study was to assess the factors of AVN in SLE patients. Materials and methods: The study included 127 patients with SLE who fulfilled 1997 American College of Rheumatology (ACR) revised criteria. Demographic data, age at SLE diagnosis, disease duration, disease activity, body mass index, clinical findings, antiphospholipid syndrome, steroid usage, dose and duration, comorbid diseases, and smoking history were recorded. Results: AVN was found in 11 of 127 (8.7%) SLE patients. Hyperlipidemia (P < 0.001), cushingoid body habitus (P < 0.001), and proteinuria (P = 0.013) were found at higher rates in the AVN group. All of the 11 AVN cases had osteoporosis (P < 0.02). In multivariate regression analysis, daily steroid usage was the only factor for development of AVN in SLE. Conclusion: The hypothesis of our study was that an alternate day steroid regimen may decrease AVN frequency in SLE patients.PubMe