Background Information and behaviour can spread through interpersonal ties. By targeting influential individuals, health interventions that harness the distributive properties of social networks may be made more effective and efficient than those that do not. Methods In this block-randomised trial of network targeting methods, we delivered two dissimilar public health interventions to 32 villages in rural Honduras (22–541 participants each; total study population of 5,773): chlorine for water purification, and multivitamins for micronutrient deficiencies. We blocked villages on the basis of network size, socioeconomic status, and baseline rates of water purification. We then randomised villages, separately for each intervention, to one of three targeting methods, introducing the interventions to 5% samples composed either of: (1) randomly selected villagers (n=9 villages for each intervention), (2) villagers with the most social ties (n=9), or (3) nominated friends of random villagers (n=9; the last strategy exploiting the “friendship paradox” of social networks). Primary endpoints were the proportion of available products redeemed by the entire population under each targeting method. Participants and data collectors were not aware of the targeting methods. The trial is registered with ClinicalTrials.gov (NCT01672580). Findings For each intervention, 9 villages (each with 1–20 initial target individuals) were randomised to each of the three targeting methods. Targeting the most highly connected individuals produced no greater adoption of the interventions than random targeting. Targeting nominated friends, however, increased adoption of the nutritional intervention by 12·2% compared to random targeting (95% CI, 6·9 to 17·9). Interpretation Introducing a health intervention to the nominated friends of random individuals can enhance that intervention’s diffusion by exploiting intrinsic properties of human social networks. This method has the additional advantage of scalability because it can be implemented without mapping the network. Deploying certain types of health interventions via network targeting, without increasing the number of individuals targeted or the resources used, may enhance the adoption and efficiency of those interventions, thereby improving population health. Funding NIH, Bill and Melinda Gates Foundation, Star Family Foundation, and the Canadian Institutes of Health Research. We thank The Clorox Company and Tishcon Corporation for their donations of supplies used in the study in Honduras.

Continuous retention is a critically important measure of long-term success in HIV treatment and the crucial component of successful treatment-as-prevention but is infrequently evaluated. Single cross-sections may overestimate successful retention and virologic outcomes. A longitudinal HIV care continuum provides greater insight into long-term outcomes and exposes disparities not evident with traditional cross-sectional care continua.

Experimental evidence in cognitive psychology and behavioral economics is transforming the way political science scholars think about how humans make decisions in areas of high complexity, uncertainty, and risk. Nearly all those studies utilize convenience samples of university students, but in the real world political elites actually make most pivotal political decisions such as threatening war or changing the course of economic policy. Highly experienced elites are more likely to exhibit the attributes of rational decisionmaking; and over the last fifteen years a wealth of studies suggest that such elites are likely to be more skilled in strategic bargaining than samples with less germane experience. However, elites are also more likely to suffer overconfidence, which degrades decisionmaking skills. We illustrate implications for political science with a case study of crisis bargaining between the US and North Korea. Variations in the experience of US elite decision-makers between 2002 and 2006 plausibly explain the large shift in US crisis signaling better than other rival hypotheses such as "Iraq fatigue." Beyond crisis bargaining other major political science theories might benefit from attention to the attributes of individual decision-makers.F or decades, a cognitive revolution has been sweeping across the many fields of social science. The key insight from this revolution is that human decisionmaking is far from perfectly rational yet follows certain patterns that are relevant for economic and political behavior. Most of the evidence about human behavior has come from experimental studies on students and other subjects that are readily available to university professors in large numbers, at little cost. 1 Such studies have immediate relevance for understanding some kinds of political behavior, such as voting, that involves analogous populations. 2 Much of politics, however, hinges on the behavior of senior politicians and bureaucrats who run national governments and international organizations. Unfortunately, experienced elites are difficult to obtain as subjects because they are generally busy, wary of clinical poking, and skittish about revealing information about their decisionmaking processes and particular choices. 3 When elites do consent to such research, sample sizes are exceptionally small, making it hard to draw general inferences. While many political scientists do acknowledge that there are differences between how elites and novices reason, the literature generally downplays such differences.A small but growing number of experimental studies done mainly in the last two decades suggests that experienced elites act differently from the population of less experienced university students who have been the mainstay of research in political psychology, behavioral economics and related scholarship on the psychology of decision-making. 4 We make two arguments about the importance of this cognitive revolution for political science. First, on methods, when studying elite decision making it is importa...

We propose a new specification framework for information hiding properties such as anonymity and privacy. The framework is based on the concept of a function view, which is a concise representation of the attacker's partial knowledge about a function. We describe system behavior as a set of functions, and formalize different information hiding properties in terms of views of these functions. We present an extensive case study, in which we use the function view framework to systematically classify and rigorously define a rich domain of identity-related properties, and to demonstrate that privacy and anonymity are independent. The key feature of our approach is its modularity. It yields precise, formal specifications of information hiding properties for any protocol formalism and any choice of the attacker model as long as the latter induce an observational equivalence relation on protocol instances. In particular, specifications based on function views are suitable for any cryptographic process calculus that defines some form of indistinguishability between processes. Our definitions of information hiding properties take into account any feature of the security model, including probabilities, random number generation, timing, etc., to the extent that it is accounted for by the formalism in which the system is specified.

A cornerstone of the theory of proof nets for unit-free multiplicative linear logic (MLL) is the abstract representation of cut-free proofs modulo inessential commutations of rules. The only known extension to additives, based on monomial weights, fails to preserve this key feature: a host of cut-free monomial proof nets can correspond to the same cut-free proof. Thus the problem of finding a satisfactory notion of proof net for unit-free multiplicativeadditive linear logic (MALL) has remained open since the inception of linear logic in 1986. We present a new definition of MALL proof net which remains faithful to the cornerstone of the MLL theory.

BackgroundIntimate partner violence (IPV) is a complex global problem, not only because it is a human rights issue, but also because it is associated with chronic mental and physical illnesses as well as acute health outcomes related to injuries for women and their children. Attitudes, beliefs, and norms regarding IPV are significantly associated with the likelihood of both IPV experience and perpetration.MethodsWe investigated whether IPV acceptance is correlated across socially connected individuals, whether these correlations differ across types of relationships, and whether social position is associated with the likelihood of accepting IPV. We used sociocentric network data from 831 individuals in rural Honduras to assess the association of IPV acceptance between socially connected individuals across 15 different types of relationships, both within and between households. We also investigated the association between network position and IPV acceptance.ResultsWe found that having a social contact that accepts IPV is strongly associated with IPV acceptance among individuals. For women the clustering of IPV acceptance was not significant in between-household relationships, but was concentrated within households. For men, however, while IPV acceptance was strongly clustered within households, men’s acceptance of IPV was also correlated with people with whom they regularly converse, their mothers and their siblings, regardless of household. We also found that IPV was more likely to be accepted by less socially-central individuals, and that the correlation between a social contact’s IPV acceptance was stronger on the periphery, suggesting that, as a norm, it is held on the periphery of the community.ConclusionOur results show that differential targeting of individuals and relationships in order to reduce the acceptability and, subsequently, the prevalence of IPV may be most effective. Because IPV norms seem to be strongly held within households, the household is probably the most logical unit to target in order to implement change. This approach would include the possible benefit of a generational effect. Finally, in social contexts in which perpetration of IPV is not socially acceptable, the most effective strategy may be to implement change not at the center but at the periphery of the community.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-2893-4) contains supplementary material, which is available to authorized users.

Proofs are traditionally syntactic, inductively generated objects. This paper presents an abstract mathematical formulation of propositional calculus (propositional logic) in which proofs are combinatorial (graph-theoretic), rather than syntactic. It defines a combinatorial proof of a proposition φ as a graph homomorphism h : C → G(φ), where G(φ) is a graph associated with φ and C is a coloured graph. The main theorem is soundness and completeness: φ is true if and only if there exists a combinatorial proof h : C → G(φ).

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