Sviluppo di sistemi mobile ad alta densita basati su comunicazioni opportunistiche wireless

In questa tesi ci si pone l'obiettivo di sviluppare sistemi distribuiti composti da device mobile che si scambiano informazioni tramite comunicazioni opportunistiche wireless peer-to-peer. Vengono inizialmente analizzate le principali tecnologie di comunicazione wireless adatte allo scopo, soffermandosi sulle reti Wifi ad hoc, delle quali vengono studiate le performance in sistemi di larga scala tramite il simulatore di reti ns-3. Successivamente viene esposto lo sviluppo di componenti software, basati su Akka Stream, per la costruzione di campi computazionali tramite comunicazioni opportunistiche tra device Android, effettuate tramite reti Wifi ad hoc.

The Design of XML-Based Model and Experiment Description Languages for Network Simulation

The Simulation Automation Framework for Experiments (SAFE) is a project created to raise the level of abstraction in network simulation tools and thereby address issues that undermine credibility. SAFE incorporates best practices in network simulationto automate the experimental process and to guide users in the development of sound scientific studies using the popular ns-3 network simulator. My contributions to the SAFE project: the design of two XML-based languages called NEDL (ns-3 Experiment Description Language) and NSTL (ns-3 Script Templating Language), which facilitate the description of experiments and network simulationmodels, respectively. The languages provide a foundation for the construction of better interfaces between the user and the ns-3 simulator. They also provide input to a mechanism which automates the execution of network simulation experiments. Additionally,this thesis demonstrates that one can develop tools to generate ns-3 scripts in Python or C++ automatically from NSTL model descriptions.

Visualization Techniques For The Analysis Of Network Simulation Results

The Simulation Automation Framework for Experiments (SAFE) streamlines the de- sign and execution of experiments with the ns-3 network simulator. SAFE ensures that best practices are followed throughout the workflow a network simulation study, guaranteeing that results are both credible and reproducible by third parties. Data analysis is a crucial part of this workflow, where mistakes are often made. Even when appearing in highly regarded venues, scientific graphics in numerous network simulation publications fail to include graphic titles, units, legends, and confidence intervals. After studying the literature in network simulation methodology and in- formation graphics visualization, I developed a visualization component for SAFE to help users avoid these errors in their scientific workflow. The functionality of this new component includes support for interactive visualization through a web-based interface and for the generation of high-quality, static plots that can be included in publications. The overarching goal of my contribution is to help users create graphics that follow best practices in visualization and thereby succeed in conveying the right information about simulation results.

Hepatitis C virus drug resistance and immune-driven adaptations: relevance to new antiviral therapy

The efficacy of specifically targeted anti-viral therapy for hepatitis C virus (HCV) (STAT-C), including HCV protease and polymerase inhibitors, is limited by the presence of drug-specific viral resistance mutations within the targeted proteins. Genetic diversity within these viral proteins also evolves under selective pressures provided by host human leukocyte antigen (HLA)-restricted immune responses, which may therefore influence STAT-C treatment response. Here, the prevalence of drug resistance mutations relevant to 27 developmental STAT-C drugs, and the potential for drug and immune selective pressures to intersect at sites along the HCV genome, is explored. HCV nonstructural (NS) 3 protease or NS5B polymerase sequences and HLA assignment were obtained from study populations from Australia, Switzerland, and the United Kingdom. Four hundred five treatment-naïve individuals with chronic HCV infection were considered (259 genotype 1, 146 genotype 3), of which 38.5% were coinfected with human immunodeficiency virus (HIV). We identified preexisting STAT-C drug resistance mutations in sequences from this large cohort. The frequency of the variations varied according to individual STAT-C drug and HCV genotype/subtype. Of individuals infected with subtype 1a, 21.5% exhibited genetic variation at a known drug resistance site. Furthermore, we identified areas in HCV protease and polymerase that are under both potential HLA-driven pressure and therapy selection and identified six HLA-associated polymorphisms (P

14-3-3 proteins interact with the beta-thymosin repeat protein Csp24.

Conditioned stimulus pathway protein 24 (Csp24) is a beta-thymosin-like protein that is homologous to other members of the family of beta-thymosin repeat proteins that contain multiple actin binding domains. Actin co-precipitates with Csp24 and co-localizes with it in the cytosol of type-B photoreceptor cell bodies. Several signal transduction pathways have been shown to regulate the phosphorylation of Csp24 and contribute to cellular plasticity. Here, we report the identification of the adapter protein 14-3-3 in lysates of the Hermissenda circumesophageal nervous system and its interaction with Csp24. Immunoprecipitation experiments using an antibody that is broadly reactive with several isoforms of the 14-3-3 family of proteins showed that Csp24 co-precipitates with 14-3-3 protein, and nervous systems stimulated with 5-HT exhibited a significant increase in co-precipitated Csp24 probed with a phosphospecific antibody as compared with controls. These results indicate that post-translational modifications of Csp24 regulate its interaction with 14-3-3 protein, and suggest that this mechanism may contribute to the control of intrinsic enhanced excitability.

Glycogen Synthase Kinase 3 is Required for Optimal AKT Activation

The phosphatidylinositol 3-kinase (PI3K) pathway, through its major effector node AKT, is critical for the promotion of cell growth, division, motility and apoptosis evasion. This signaling axis is therefore commonly targeted in the form of mutations and amplifications in a myriad of malignancies. Glycogen synthase kinase 3 (GSK3) was first discovered as the kinase responsible for phosphorylating and inhibiting the activity of glycogen synthase, ultimately antagonizing the storage of glucose as glycogen. Its activity counteracts the effects of insulin in glucose metabolism and AKT has long been recognized as one of the key molecules capable of phosphorylating GSK3 and inhibiting its activity. However, here we demonstrate that GSK3 is required for optimal phosphorylation and activation of AKT in different malignant cell lines, and that this effect is independent of the type of growth factor stimulation and can happen even in basal states. Both GSK3 alpha and GSK3 beta isoforms are necessary for AKT to become fully active, displaying a redundant role in the setting. We also demonstrate that this effect of GSK3 on AKT phosphorylation and full activation is dependent on its kinase activity, since highly specific inhibitors targeting GSK3 catalytic activity also promote a reduction in phosphorylated AKT. Analysis of reverse phase protein array screening of MDA-MB-231 breast cancer cells treated with RNA interference targeting GSK3 unexpectedly revealed an increase in levels of phosphorylated MAPK14 (p38). Treatment with the selective p38 inhibitor SB 202190 rescued AKT activation in that cell line, corroborating the importance of unbiased proteomic analysis in exposing cross-talks between signaling networks and demonstrating a critical role for p38 in the regulation of AKT phosphorylation.

Distributed Rate Allocation in Inter-Session Network Coding

In this work, we propose a distributed rate allocation algorithm that minimizes the average decoding delay for multimedia clients in inter-session network coding systems. We consider a scenario where the users are organized in a mesh network and each user requests the content of one of the available sources. We propose a novel distributed algorithm where network users determine the coding operations and the packet rates to be requested from the parent nodes, such that the decoding delay is minimized for all clients. A rate allocation problem is solved by every user, which seeks the rates that minimize the average decoding delay for its children and for itself. Since this optimization problem is a priori non-convex, we introduce the concept of equivalent packet flows, which permits to estimate the expected number of packets that every user needs to collect for decoding. We then decompose our original rate allocation problem into a set of convex subproblems, which are eventually combined to obtain an effective approximate solution to the delay minimization problem. The results demonstrate that the proposed scheme eliminates the bottlenecks and reduces the decoding delay experienced by users with limited bandwidth resources. We validate the performance of our distributed rate allocation algorithm in different video streaming scenarios using the NS-3 network simulator. We show that our system is able to take benefit of inter-session network coding for simultaneous delivery of video sessions in networks with path diversity.

Evaluating the Harris County TexHealth 3-Share Plan: An exploratory study

An important health issue in the United States today is the large number of people who have problems accessing needed health care because they lack health insurance coverage. Providing health insurance coverage for the working uninsured is a particularly significant challenge in Texas, which has the highest percentage of uninsured in the nation. In response to the low rate of employer-sponsored coverage in the Houston area and the growing numbers of uninsured, the Harris County Health Care Alliance (HCHA) developed and implemented the Harris County 3-Share Plan. A 3-Share Plan is not insurance, but provides health coverage in the form of a benefits package to employers who subscribe to the program and offer it to their employees. ^ A cross sectional study design was conducted to describe 3-Share employer and employee participants and evaluate their outcomes after its first year of operation. Between September and December 2011, 85% of employers enrolled in the 3-Share Plan completed a survey about the affordability of the 3-Share Plan, their satisfaction with the Plan, and the Plan's impact on employee recruitment, retention, productivity, and absenteeism. Forty-five percent of employees enrolled in the 3-Share Plan responded to a survey asking about the affordability of the 3-Share plan, accessibility of health care, availability of providers on the plan, health plan availability, utilization of primary care providers and the ER, and satisfaction with the plan. ^ A summary of the findings shows employers and employees say that they joined the plan because of the low-cost, and once they had participated in the Plan, the majority of employers and employees found that it is affordable for them. The majority of employees say they are getting access easily and without delay, but for those who aren't able to get access, or are delayed, the main cause is related to non-financial barriers to care. Ultimately, employees are satisfied with the 3-Share, and they plan to continue with health coverage under the 3-Share Plan. The 3-Share Plan will keep people in a system of care, and promote health, which will benefit the individuals, the businesses and the community of Harris County.^

Evaluating the Harris County TexHealth 3-Share plan: An exploratory study

An important health issue in the United States today is the large number of people who have problems accessing needed health care because they lack health insurance coverage. Providing health insurance coverage for the working uninsured is a particularly significant challenge in Texas, which has the highest percentage of uninsured in the nation. In response to the low rate of employer-sponsored coverage in the Houston area and the growing numbers of uninsured, the Harris County Health Care Alliance (HCHA) developed and implemented the Harris County 3-Share Plan. A 3-Share Plan is not insurance, but provides health coverage in the form of a benefits package to employers who subscribe to the program and offer it to their employees. ^ A cross sectional study design was conducted to describe 3-Share employer and employee participants and evaluate their outcomes after its first year of operation. Between September and December 2011, 85% of employers enrolled in the 3-Share Plan completed a survey about the affordability of the 3-Share Plan, their satisfaction with the Plan, and the Plan's impact on employee recruitment, retention, and productivity. Forty-five percent of employees enrolled in the 3-Share Plan responded to a survey asking about the affordability of the 3-Share plan, accessibility of providers on the plan, satisfaction, and utilization of primary care providers and the ER. ^ A summary of the findings shows employers and employees say that they joined the plan because of the low-cost, and once they had participated in the Plan, the majority of employers and employees found that it is affordable for them. The majority of employees say they are getting access easily and without delay, but for those who aren't able to get access, or are delayed, the main cause is related to non-financial barriers to care. Ultimately, employees are satisfied with the 3-Share, and they plan to continue with health coverage under the 3-Share Plan. The 3-Share Plan will keep people in a system of care, and promote health, which will benefit the individuals, the businesses and the community of Harris County.^