Behavioural homogenisation with spillovers in a normative domain

The importance of culture for human social evolution hinges largely on the extent to which culture supports outcomes that would not otherwise occur. An especially controversial claim is that social learning leads groups to coalesce around group-typical behaviours and associated social norms that spill over to shape choices in asocial settings. To test this, we conducted an experiment with 878 groups of participants in 116 communities in Sudan. Participants watched a short film and evaluated the appropriate way to behave in the situation dramatized in the film. Each session consisted of an asocial condition in which participants provided private evaluations and a social condition in which they provided public evaluations. Public evaluations allowed for social learning. Across sessions, we randomized the order of the two conditions. Public choices dramatically increased the homogeneity of normative evaluations. When the social condition was first, this homogenizing effect spilled over to subsequent asocial conditions. The asocial condition when first was thus alone in producing distinctly heterogeneous groups. Altogether, information about the choices of others led participants to converge rapidly on similar normative evaluations that continued to hold sway in subsequent asocial settings. These spillovers were at least partly owing to the combined effects of conformity and self-consistency. Conformity dominated self-consistency when the two mechanisms were in conflict, but self-consistency otherwise produced choices that persisted through time. Additionally, the tendency to conform was heterogeneous. Females conformed more than males, and conformity increased with the number of other people a decision-maker observed before making her own choice

A Novel Ultrasonic Method for Accurate Characterization of Microstructural Gradients in Monolithic and Composite Tubular Structures

Prior studies have shown that ultrasonic velocity/time-of-flight imaging that uses back surface echo reflections to gauge volumetric material quality is well suited (perhaps more so than is the commonlyused peak amplitude c-scanning) for quantitative characterization of microstructural gradients. Such gradients include those due to pore fraction, density, fiber fraction, and chemical composition variations [11–15]. Variations in these microstructural factors can affect the uniformity of physical performance (including mechanical [stiffness, strength], thermal [conductivity], and electrical [conductivity, superconducting transition temperature], etc. performance) of monolithic and composite [1,3,6,12]. A weakness of conventional ultrasonic velocity/time-of-flight imaging (as well as to a lesser extent ultrasonic peak amplitude c-scanning where back surface echoes are gated [17] is that the image shows the effects of thickness as well as microstructural variations unless the part is uniformly thick. This limits this type of imaging’s usefulness in practical applications. The effect of thickness is easily observed from the equation for pulse-echo waveform time-of-flight (2τ) between the first front surface echo (FS) and the first back surface echo (B1), or between two successive back surface echoes where: 2τ=(2d)V (1) where d is the sample thickness and V is the velocity of ultrasound in the material. Interpretation of the time-of-flight image is difficult as thickness variation effects can mask or overemphasize the true microstructural variation portrayed in the image of a part containing thickness variations. Thickness effects on time-of-flight can also be interpreted by rearranging equation (1) to calculate velocity: V=(2d)2τ (2) such that velocity is inversely proportional to time-of-flight. Velocity and time-of-flight maps will be affected similarly (although inversely in terms of magnitude) by thickness variations, and velocity maps are used in this investigation to indicate time-of-flight variations.</p

Cooperation and Contagion in Web-Based, Networked Public Goods Experiments

A longstanding idea in the literature on human cooperation is that cooperation should be reinforced when conditional cooperators are more likely to interact. In the context of social networks, this idea implies that cooperation should fare better in highly clustered networks such as cliques than in networks with low clustering such as random networks. To test this hypothesis, we conducted a series of web-based experiments, in which 24 individuals played a local public goods game arranged on one of five network topologies that varied between disconnected cliques and a random regular graph. In contrast with previous theoretical work, we found that network topology had no significant effect on average contributions. This result implies either that individuals are not conditional cooperators, or else that cooperation does not benefit from positive reinforcement between connected neighbors. We then tested both of these possibilities in two subsequent series of experiments in which artificial seed players were introduced, making either full or zero contributions. First, we found that although players did generally behave like conditional cooperators, they were as likely to decrease their contributions in response to low contributing neighbors as they were to increase their contributions in response to high contributing neighbors. Second, we found that positive effects of cooperation were contagious only to direct neighbors in the network. In total we report on 113 human subjects experiments, highlighting the speed, flexibility, and cost-effectiveness of web-based experiments over those conducted in physical labs

System Theoretic Process Analysis: a literature survey on the approaches used for improving the safety in complex systems

Computer systems are becoming increasingly complex, specially interactive software systems, namely software user interfaces. The scientic community relies on dierent methods to assess their safety. This article provides an updated literature survey on hazard analysis approaches used to improve the safety of complex systems. To support the survey, we conceptualise complex systems, highlighting the challenge in terms of assessing their safety. We provide a brief overview on the approaches historically available to tackle issues in those systems, along with their most common methods. Finally, the article focuses in one method of a non-traditional approach, which is described in more details, along with some of its extensions, which seeks to improve the hazard analysis in complex systems

A verified algorithm enumerating event structures

An event structure is a mathematical abstraction modeling concepts as causality, conflict and concurrency between events. While many other mathematical structures, including groups, topological spaces, rings, abound with algorithms and formulas to generate, enumerate and count particular sets of their members, no algorithm or formulas are known to generate or count all the possible event structures over af inite set of events. We present an algorithm to generate such a family, along with a functional implementation verified using Isabelle/HOL. As byproducts, we obtain a verified enumeration of all possible preorders and partial orders. While the integer sequences counting preorders and partial orders are already listed on OEIS (On-line Encyclopedia of Integer Sequences), the one counting event structures is not. We therefore used our algorithm to submit a formally verified addition, which has been successfully reviewed and is now part of the OEIS.Postprin

Altruism can proliferate through group/kin selection despite high random gene flow

The ways in which natural selection can allow the proliferation of cooperative behavior have long been seen as a central problem in evolutionary biology. Most of the literature has focused on interactions between pairs of individuals and on linear public goods games. This emphasis led to the conclusion that even modest levels of migration would pose a serious problem to the spread of altruism in group structured populations. Here we challenge this conclusion, by analyzing evolution in a framework which allows for complex group interactions and random migration among groups. We conclude that contingent forms of strong altruism can spread when rare under realistic group sizes and levels of migration. Our analysis combines group-centric and gene-centric perspectives, allows for arbitrary strength of selection, and leads to extensions of Hamilton's rule for the spread of altruistic alleles, applicable under broad conditions.Comment: 5 pages, 2 figures. Supplementary material with 50 pages and 26 figure

Emerging communities of child-healthcare practice in the management of long-term conditions such as chronic kidney disease: Qualitative study of parents' accounts

Background: Parents of children and young people with long-term conditions who need to deliver clinical care to their child at home with remote support from hospital-based professionals, often search the internet for care-giving information. However, there is little evidence that the information available online was developed and evaluated with parents or that it acknowledges the communities of practice that exist as parents and healthcare professionals share responsibility for condition management. Methods. The data reported here are part of a wider study that developed and tested a condition-specific, online parent information and support application with children and young people with chronic-kidney disease, parents and professionals. Semi-structured interviews were conducted with 19 fathers and 24 mothers who had recently tested the novel application. Data were analysed using Framework Analysis and the Communities of Practice concept. Results: Evolving communities of child-healthcare practice were identified comprising three components and several sub components: (1) Experiencing (parents making sense of clinical tasks) through Normalising care, Normalising illness, Acceptance & action, Gaining strength from the affected child and Building relationships to formalise a routine; (2) Doing (Parents executing tasks according to their individual skills) illustrated by Developing coping strategies, Importance of parents' efficacy of care and Fear of the child's health failing; and (3) Belonging/Becoming (Parents defining task and group members' worth and creating a personal identity within the community) consisting of Information sharing, Negotiation with health professionals and Achieving expertise in care. Parents also recalled factors affecting the development of their respective communities of healthcare practice; these included Service transition, Poor parent social life, Psycho-social affects, Family chronic illness, Difficulty in learning new procedures, Shielding and avoidance, and Language and cultural barriers. Health care professionals will benefit from using the communities of child-healthcare practice model when they support parents of children with chronic kidney disease. Conclusions: Understanding some of the factors that may influence the development of communities of child-healthcare practice will help professionals to tailor information and support for parents learning to manage their child's healthcare. Our results are potentially transferrable to professionals managing the care of children and young people with other long-term conditions. © 2014 Carolan et al.; licensee BioMed Central Ltd

Expression of transforming growth factor-β (TGF-β) in chronic idiopathic cough

In patients with chronic idiopathic cough, there is a chronic inflammatory response together with evidence of airway wall remodelling and an increase in airway epithelial nerves expressing TRPV-1. We hypothesised that these changes could result from an increase in growth factors such as TGFβ and neurotrophins

No evidence for an association between the -36A>C phospholamban gene polymorphism and a worse prognosis in heart failure

Background: In Brazil, heart failure leads to approximately 25,000 deaths per year. Abnormal calcium handling is a hallmark of heart failure and changes in genes encoding for proteins involved in the re-uptake of calcium might harbor mutations leading to inherited cardiomyopathies. Phospholamban (PLN) plays a prime role in cardiac contractility and relaxation and mutations in the gene encoding PLN have been associated with dilated cardiomyopathy. In this study, our objective was to determine the presence of the -36A>C alteration in PLN gene in a Brazilian population of individuals with HF and to test whether this alteration is associated with heart failure or with a worse prognosis of patients with HF. Methods: We genotyped a cohort of 881 patients with HF and 1259 individuals from a cohort of individuals from the general population for the alteration -36A>C in the PLN gene. Allele and genotype frequencies were compared between groups (patients and control). In addition, frequencies or mean values of different phenotypes associated with cardiovascular disease were compared between genotypic groups. Finally, patients were prospectively followed-up for death incidence and genotypes for the -36A>C were compared regarding mortality incidence in HF patients. Results: No significant association was found between the study polymorphism and HF in our population. In addition, no association between PLN -36A>C polymorphism and demographic, clinical and functional characteristics and mortality incidence in this sample of HF patients was observed. Conclusion: Our data do not support a role for the PLN -36A>C alteration in modulating the heart failure phenotype, including its clinical course, in humans