Networking - A Statistical Physics Perspective

Efficient networking has a substantial economic and societal impact in a broad range of areas including transportation systems, wired and wireless communications and a range of Internet applications. As transportation and communication networks become increasingly more complex, the ever increasing demand for congestion control, higher traffic capacity, quality of service, robustness and reduced energy consumption require new tools and methods to meet these conflicting requirements. The new methodology should serve for gaining better understanding of the properties of networking systems at the macroscopic level, as well as for the development of new principled optimization and management algorithms at the microscopic level. Methods of statistical physics seem best placed to provide new approaches as they have been developed specifically to deal with non-linear large scale systems. This paper aims at presenting an overview of tools and methods that have been developed within the statistical physics community and that can be readily applied to address the emerging problems in networking. These include diffusion processes, methods from disordered systems and polymer physics, probabilistic inference, which have direct relevance to network routing, file and frequency distribution, the exploration of network structures and vulnerability, and various other practical networking applications.Comment: (Review article) 71 pages, 14 figure

Social distancing strategies against disease spreading

The recurrent infectious diseases and their increasing impact on the society has promoted the study of strategies to slow down the epidemic spreading. In this review we outline the applications of percolation theory to describe strategies against epidemic spreading on complex networks. We give a general outlook of the relation between link percolation and the susceptible-infected-recovered model, and introduce the node void percolation process to describe the dilution of the network composed by healthy individual, $i.e$, the network that sustain the functionality of a society. Then, we survey two strategies: the quenched disorder strategy where an heterogeneous distribution of contact intensities is induced in society, and the intermittent social distancing strategy where health individuals are persuaded to avoid contact with their neighbors for intermittent periods of time. Using percolation tools, we show that both strategies may halt the epidemic spreading. Finally, we discuss the role of the transmissibility, $i.e$, the effective probability to transmit a disease, on the performance of the strategies to slow down the epidemic spreading.Comment: to be published in "Perspectives and Challenges in Statistical Physics and Complex Systems for the Next Decade", Word Scientific Pres

The Silent Epidemic: Perspectives of High School Dropouts

Presents findings from a survey that examines why some students do not complete their high school education, and what academic and personal supports would have helped them stay in school. Includes recommendations for improving graduation rates

Epidemic Thresholds with External Agents

We study the effect of external infection sources on phase transitions in epidemic processes. In particular, we consider an epidemic spreading on a network via the SIS/SIR dynamics, which in addition is aided by external agents - sources unconstrained by the graph, but possessing a limited infection rate or virulence. Such a model captures many existing models of externally aided epidemics, and finds use in many settings - epidemiology, marketing and advertising, network robustness, etc. We provide a detailed characterization of the impact of external agents on epidemic thresholds. In particular, for the SIS model, we show that any external infection strategy with constant virulence either fails to significantly affect the lifetime of an epidemic, or at best, sustains the epidemic for a lifetime which is polynomial in the number of nodes. On the other hand, a random external-infection strategy, with rate increasing linearly in the number of infected nodes, succeeds under some conditions to sustain an exponential epidemic lifetime. We obtain similar sharp thresholds for the SIR model, and discuss the relevance of our results in a variety of settings.Comment: 12 pages, 2 figures (to appear in INFOCOM 2014

ROLE OF INFORMATION AND COMMUNICATION TECHNOLOGY (ICT) IN HIV/AIDS HEALTH COMMUNICATION IN SLUMS (A Case of Kawangware Division, Nairobi Kenya)

Purpose: Information and Communication Technologies are key elements of a civil society response to the HIV/AIDS epidemic, enabling advocacy, mobilization, and empowerment of People Living with HIV (PLWHA), women, and other vulnerable groups. This study sought to investigate the role of Information and Communication Technology (ICT) in HIV/AIDS Health Communication in slums through a case study of a project sponsored by AfriAfya in Kawangware division, Nairobi Kenya. AfriAfya, also known as the African Network for Health Knowledge Management and Communication, is a consortium of health NGOs namely: Aga Khan Health Services; African Medical and Research Foundation (AMREF); CARE Kenya; Christian Health Association of Kenya; HealthNet Kenya; the Ministry of Health, Kenya; PLAN International; and World Vision International, Kenya. AfriAfya was set up in April 2000 to explore the ways of harnessing ICTs for community health in rural and marginalized communities.  The study was guided by the following specific objectives: (i) to analyze the ICT interventions and tools used in the fight against HIV/AIDS in Kenya; to examine the benefits derived from adoption of ICTs in the fight against HIV/AIDS in Kenyan slums; to assess the challenges faced in the adoption of ICTs in the fight against HIV/AIDS in the slums in Kenya; and to recommend strategies on how best to employ ICTs in the fight against HIV/AIDS in Kenyan slums. Methods: The data collected by this study was analyzed by descriptive statistics such as percentages, frequencies and tables. In addition, standard deviations and mean scores were used to present information pertaining to the study objectives. The information was presented and discussed as per the objectives and research questions of the study. Findings: Findings of the study indicate that all the four objectives were met as follows:- The tools used in the fight against HIV/AIDS in Kenya were established as being e-mail discussion groups, Internet, Dissemination of information on World Wide Web (www), Radio, Television, and  Distance learning systems. The interventions used in the fight against HIV/AIDS in Kenya were established as being Prevention:-Dissemination of prevention messages as well as prevention services to target groups such as commercial sex workers; School Based Education:- Education and life skills training in the schools for effecting appropriate behavioral changes among youth; and Education of Health Care Workers :- ICTs are being used to improve access to information, education, and communication for health workers using, Internet, email discussion groups, and distance learning systems. The benefits derived from adoption of ICTs in the fight against HIV/AIDS in Kenyan slums were determined as being Social change; empowerment and reduction of vulnerability; advocacy, mobilization, networking and capacity building; Remote consultations and diagnosis; Information sharing; Remote mentoring; Facilitation of Distance learning teaching; and Online Counseling. The challenges of adoption of the ICTs in HIV/AIDS Health Communication were established as being: - Limited connectivity; Poor ICT infrastructure status; High costs of accessing the Internet; and Language barrier. Key Words: Information & Communication Technology, HIV/AIDS, Community Based Organizations

The Behavior of Epidemics under Bounded Susceptibility

We investigate the sensitivity of epidemic behavior to a bounded susceptibility constraint -- susceptible nodes are infected by their neighbors via the regular SI/SIS dynamics, but subject to a cap on the infection rate. Such a constraint is motivated by modern social networks, wherein messages are broadcast to all neighbors, but attention spans are limited. Bounded susceptibility also arises in distributed computing applications with download bandwidth constraints, and in human epidemics under quarantine policies. Network epidemics have been extensively studied in literature; prior work characterizes the graph structures required to ensure fast spreading under the SI dynamics, and long lifetime under the SIS dynamics. In particular, these conditions turn out to be meaningful for two classes of networks of practical relevance -- dense, uniform (i.e., clique-like) graphs, and sparse, structured (i.e., star-like) graphs. We show that bounded susceptibility has a surprising impact on epidemic behavior in these graph families. For the SI dynamics, bounded susceptibility has no effect on star-like networks, but dramatically alters the spreading time in clique-like networks. In contrast, for the SIS dynamics, clique-like networks are unaffected, but star-like networks exhibit a sharp change in extinction times under bounded susceptibility. Our findings are useful for the design of disease-resistant networks and infrastructure networks. More generally, they show that results for existing epidemic models are sensitive to modeling assumptions in non-intuitive ways, and suggest caution in directly using these as guidelines for real systems