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Issue linkage is often advocated as a powerful mechanism to encourage cooperation on issues where free-riding incentives are significant. The basic idea is to link cooperation on such issues with cooperation on issues that provide (partially) excludable benefits and are therefore less susceptible to free-riding. In this paper, we take a coalition formation approach and study the effects of issue linkage on overall cooperation levels and welfare. We show that, when the linked issues are independent, issue linkage is not necessarily welfare improving; in fact, unless the less critical issue is almost perfectly excludable, issue linkage leads to a welfare loss. By contrast, a generalized enlargement of cooperation and an increase in welfare are obtainable when the linked issues are "complements". Using concepts from network theory, we further provide insights into the design of cost-effective (minimally connected) linkage architectures when more than two issues are at stake. [ABSTRACT FROM AUTHOR]

This paper examines experimentally how reputational uncertainty and the rate of change of the social environment determine cooperation. Reputational uncertainty significantly decreases cooperation, while a fast-changing social environment only causes a second-order qualitative increase in cooperation. At the individual level, reputational uncertainty induces more leniency and forgiveness in imposing network punishment through the link proposal and removal processes, inhibiting the formation of cooperative clusters. However, this effect is significant only in the fast-changing environment and not in the slow-changing environment. A substitution pattern between network punishment and action punishment (retaliatory defection) explains this discrepancy across the two social environments. [ABSTRACT FROM AUTHOR]

We consider a fixed network of players endowed with idiosyncratic preferences over actions and involved in interactions of various types. The aim is to investigate the interplay between idiosyncratic preferences and interactional incentives on a network. The earlier literature demonstrated the conflict between players' intrinsic preferences and coordination incentives. This paper shows that such a conflict is also present in contexts in which players do not necessarily aim at coordination with their peers. The introduction of action preferences changes equilibrium outcomes in a non-trivial fashion: some equilibria disappear, while other, qualitatively new ones, appear. We characterize equilibria for a large class of games, including games of strategic complements and strategic substitutes, and outline a subclass with a unique equilibrium in which all players follow their idiosyncratic action preferences. This equilibrium is Pareto optimal and for many games is also a unique efficient profile. [ABSTRACT FROM AUTHOR]

Several approaches and techniques exist to resolve load balancing problem in general and torus topology networks. Graph methods are natural ways to perform balancing of routing paths. A routing balancing algorithm must operate within the constraints of the underlying network architecture that limits several parameters, such as the number of logical paths in the network. In this paper, we consider a torus topology that is one of the common topologies that are used in high performance computing systems. We introduce a routing graph that corresponds to a interconnect topology, abstracts interconnect routing rules, providing one-to-one correspondence of network routes and graph paths. We propose a deadlock-free routing algorithm based on a fast single-source shortest path algorithm in a routing graph for the deterministic routing of a torus topology interconnect with a single virtual channel. The proposed algorithm is a tradeoff between two existing routing algorithms, also the algorithm is optimized for multidimensional torus topology and can be applied to any torus topology HPC system. We present a complete description of a routing graph that abstracts the Angara interconnect with 4D torus topology. We evaluated the proposed routing algorithm and benchmarked the maximum performance improvement of 71% for the Alltoall pattern for torus topology systems up to 432 nodes on the Angara interconnect simulator. The performance improvement of more than 5% was obtained for the NPB FT and IS application kernels on a 32-node supercomputer. • A routing graph abstracts network routing rules. • A deadlock-free routing algorithm is based on a fast single-source shortest path algorithm and optimized for a torus topology. • A routing graph for the Angara network reflects the restrictions on a further packet route with the previous route steps in mind. • The maximum performance improvement is 71% for the Alltoall pattern on the simulated torus topology systems up to 432 nodes. • The performance improvement on the 32-node Angara based cluster is 5% for the NPB FT and IS application kernels. [ABSTRACT FROM AUTHOR]

This research explores the networks of technological knowledge that influenced changes in the iron production practices of western Uganda in the second half of the second millennium AD. Temporal and spatial variability in technological processes were observed within the research area, in terms of the style and construction of the furnaces, the use of a manganese-rich flux, and the configuration of tuyères. These shifts were considered in relation to the social dimensions of iron production, specifically the protection of technical knowledge. Informed by ethnographic data from the study area, variations were noted in the participation in, or exclusion from, iron production activity on the basis of gender and clan affiliation. This stands in contrast to ethno-historic accounts that speak of a strongly regulated production environment. This paper considers that an uncritical emphasis on conservatism provides an inadequate framework for addressing long-term change in iron production technologies. It suggests that constellations of knowledge in western Uganda fostered the potential for innovation and experimentation, resulting in dynamic technological practice. This paper urges a more nuanced discussion of how complex metallurgical technologies transform and move within cultural and physical landscapes, with ramifications for how we conceptualize the emergence and adoption of early technologies. [ABSTRACT FROM AUTHOR]

How does the structure of an organization affect corruption? This paper analyzes a model that views organizations as networks on which coalitions of corrupt accomplices may form. This network approach to corruption provides new insights into the problem: (i) corruption will arise in enclaves, i.e. coalitions that minimize joint exposure to witnesses, (ii) making the organization more connected may increase corruption, and (iii) corruption will involve larger coalitions under better monitoring. Simulation results also suggest that more hierarchical organizations are more corrupt than flatter organizations. I test these predictions in the lab. Results confirm the predictions and reveal a systematic deviation that has implications for why better monitoring reduces corruption: participants disproportionately fail to realize larger coalitions, which are more necessary under good monitoring. Results suggest it would be sensible to redesign public agencies to puncture the isolation of enclaves. [ABSTRACT FROM AUTHOR]

This paper studies fictitious play in networks of noncooperative two-person games. We show that continuous-time fictitious play converges to the set of Nash equilibria if the overall n -person game is zero-sum. Moreover, the rate of convergence is 1 / τ , regardless of the size of the network. In contrast, arbitrary n -person zero-sum games with bilinear payoff functions do not possess the continuous-time fictitious-play property. As extensions, we consider networks in which each bilateral game is either strategically zero-sum, a weighted potential game, or a two-by-two game. In those cases, convergence requires a condition on bilateral payoffs or, alternatively, that the network is acyclic. Our results hold also for the discrete-time variant of fictitious play, which implies, in particular, a generalization of Robinson's theorem to arbitrary zero-sum networks. Applications include security games, conflict networks, and decentralized wireless channel selection. [ABSTRACT FROM AUTHOR]

This paper provides an in-depth understanding of social dynamics in the form of kinship ties in matrilineal societies. It unpacks gender roles and relationships at the community level to understand how social structures, created by the pattern of relations, enhance or hinder coping initiatives during lake recessions in the Lake Chilwa socio-ecological system. Using qualitative and quantitative methods including in-depth interviews, Focus Group Discussions (FGD) and household questionnaires, this paper provides insights into how people in the Lake Chilwa social-ecological system prepare for and cope with Lake Chilwa water recessions by capitalising on their social networks. The findings have shown that during lake recessions poor households in the Lake Chilwa socio-ecological system are cushioned by fellow households through lineage networks. There is strong tradition secured through kinship ties where the generic term ‘mwambo wathu’ (our tradition) embraces a group of formative norms enforced via a series of rules and rituals. Based in a matrilineal system, women have strong rights over land allocation and use in which the female sorority group ‘mbumba’ is very stable. There is a great deal of reciprocity and food redistribution among the households. This self-organization provides deeper meaning about how people assimilate the dynamics affecting their social and natural environments. Specifically the findings provide evidence on how households, communities and their livelihoods in Africa are reconstructed as natural resources fluctuate. [ABSTRACT FROM AUTHOR]

Abstract Geometric gradient flows for elastic energies of Willmore type play an important role in mathematics and in many applications. The evolution of elastic curves has been studied in detail both for closed as well as for open curves. Although elastic flows for networks also have many interesting features, they have not been studied so far from the point of view of mathematical analysis. So far it was not even clear what are appropriate boundary conditions at junctions. In this paper we give a well-posedness result for Willmore flow of networks in different geometric settings and hence lay a foundation for further mathematical analysis. A main point in the proof is to check whether different proposed boundary conditions lead to a well posed problem. In this context one has to check the Lopatinskii–Shapiro condition in order to apply the Solonnikov theory for linear parabolic systems in Hölder spaces which is needed in a fixed point argument. We also show that the solution we get is unique in a purely geometric sense. [ABSTRACT FROM AUTHOR]

Abstract In this paper two cost sharing solutions for minimum cost spanning tree problems are introduced, the degree adjusted folk solution and the cost adjusted folk solution. These solutions overcome the problem of the classical reductionist folk solution as they have considerable strict ranking power, without breaking established axioms. As such they provide an affirmative answer to an open question, put forward in Bogomolnaia and Moulin (2010). [ABSTRACT FROM AUTHOR]

This paper investigates the welfare effect of income redistribution in the private provision of public goods on networks. We first show that the welfare effect of income redistribution is determined by Bonacich centrality. Then we develop an index based on the network structure of interactions, which, roughly speaking, measures the welfare effect of income redistribution confined to a component of contributors. The proposed index vanishes when applied to large components of contributors that display special segregated interactions, which suggests an “asymptotic neutrality” of redistributive policies. [ABSTRACT FROM AUTHOR]

The paper analyzes the optimal targeting strategies of a planner (a governmental agency, a firm) who aims to increase the aggregate action of a population. The agents interact through a social network and react to their exposure to neighbors' actions. The reaction function describes, for example, the best response in a strategic game, a mechanical influence in a contagion disease or a mimetic behavior. The reaction is assumed to be increasing in exposure, resulting in complementarity in actions. When it is linear, the optimal planner's strategies are explicit, characterized by well-known centralities indices computed on the bilateral impacts. When the reaction function is concave or convex, the optimal strategies depend not only on the impacts but also on the pattern of agents' attentions. The value of information on the interaction structure is shown to be (almost always) positive and related to some form of heterogeneity between agents. [ABSTRACT FROM AUTHOR]

The study of functional connectivity using magnetoencephalography (MEG) is an expanding area of neuroimaging, and adds an extra dimension to the more common assessments made using fMRI. The importance of such metrics is growing, with recent demonstrations of their utility in clinical research, however previous reports suggest that whilst group level resting state connectivity is robust, single session recordings lack repeatability. Such robustness is critical if MEG measures in individual subjects are to prove clinically valuable. In the present paper, we test how practical aspects of experimental design affect the intra-subject repeatability of MEG findings; specifically we assess the effect of co-registration method and data recording duration. We show that the use of a foam head-cast, which is known to improve co-registration accuracy, increased significantly the between session repeatability of both beamformer reconstruction and connectivity estimation. We also show that recording duration is a critical parameter, with large improvements in repeatability apparent when using ten minute, compared to five minute recordings. Further analyses suggest that the origin of this latter effect is not underpinned by technical aspects of source reconstruction, but rather by a genuine effect of brain state; short recordings are simply inefficient at capturing the canonical MEG network in a single subject. Our results provide important insights on experimental design and will prove valuable for future MEG connectivity studies. [ABSTRACT FROM AUTHOR]

While, in theory, the school matching problem is a static non-cooperative one-shot game, in reality the “matching game” is played by parents who choose their strategies after consulting or chatting with other parents in their social networks. In this paper we compare the performance of the Boston and the Gale–Shapley mechanisms in the presence of chatting through social networks. Our results indicate that allowing subjects to chat has an important impact on the likelihood that subjects change their strategies and also on the welfare and stability of the outcomes determined by the mechanism. [ABSTRACT FROM AUTHOR]

Increasing concerns about climate change have given rise to the formation of International Environmental Agreements (IEAs) as a possible solution to limit global pollution effects. In this paper, we study the stability of IEAs in a repeated game framework where we restrict to strategies which are simple and invariant to renegotiation. Our main contribution is that we characterize necessary and sufficient conditions for stability of an IEA when pollution has both a global and local effect. Local pollution spillovers are represented by a network structure. We find that stable IEAs exist if the network structure is balanced. Too large asymmetries in the degree of local spillovers may, however, lead to non-existence of stable structures. We also discuss the implications of our results for welfare. The generality of our approach allows for several applications, in particular the provision of public goods. [ABSTRACT FROM AUTHOR]

Markov dynamics constitute one of the most fundamental models of random motion between the states of a system of interest. Markov dynamics have diverse applications in many fields of science and engineering, and are particularly applicable in the context of random motion in networks. In this paper we present a two-dimensional gauging method of the randomness of Markov dynamics. The method–termed Markov Stochasticity Coordinates –is established, discussed, and exemplified. Also, the method is tweaked to quantify the stochasticity of the first-passage-times of Markov dynamics, and the socioeconomic equality and mobility in human societies. [ABSTRACT FROM AUTHOR]

In this paper we construct high order finite volume schemes on networks of hyperbolic conservation laws with coupling conditions involving ODEs. We consider two generalized Riemann solvers at the junction, one of Toro–Castro type and a solver of Harten, Enquist, Osher, Chakravarthy type. The ODE is treated with a Taylor method or an explicit Runge–Kutta scheme, respectively. Both resulting high order methods conserve quantities exactly if the conservation is part of the coupling conditions. Furthermore we present a technique to incorporate lumped parameter models, which arise from simplifying parts of a network. The high order convergence and the robust capturing of shocks are investigated numerically in several test cases. [ABSTRACT FROM AUTHOR]

The new approach to classification of the epilepsies emphasizes the role of dysfunction in networks in defining types of epilepsies. This paper reviews the structural and neuropsychological deficits in two types of childhood epilepsy: frontal lobe and temporal lobe epilepsy. The evidence for and against a pattern of specificity of deficits in executive function and memory associated with these two types of epilepsies is presented. The evidence varies with the methodologies used in the studies, but direct comparison of the two types of epilepsies does not suggest a clear-cut mapping of function onto structure. These findings are discussed in light of the concept of network dysfunction. The evidence supports the conceptualization of epilepsy as a network disease. Implications for future work in the neuropsychology of pediatric epilepsy are suggested. This article is part of a Special Issue entitled “The new approach to classification: Rethinking cognition and behavior in epilepsy”. [ABSTRACT FROM AUTHOR]

Information on which weed species are present within agricultural fields is important for site specific weed management. This paper presents a method that is capable of recognising plant species in colour images by using a convolutional neural network. The network is built from scratch trained and tested on a total of 10,413 images containing 22 weed and crop species at early growth stages. These images originate from six different data sets, which have variations with respect to lighting, resolution, and soil type. This includes images taken under controlled conditions with regard to camera stabilisation and illumination, and images shot with hand-held mobile phones in fields with changing lighting conditions and different soil types. For these 22 species, the network is able to achieve a classification accuracy of 86.2%. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyzes the impact of infrastructure investment on Spanish economic growth between 1850 and 1935. Using new infrastructure data and VAR techniques, this paper shows that the growth impact of local-scope infrastructure investment was positive, but returns to investment in large nation-wide networks were not significantly different from zero. Two complementary explanations are suggested for the last result. On the one hand, public intervention and the application of non-efficiency investment criteria were very intense in large network construction. On the other hand, returns to new investment in large networks might have decreased dramatically once the basic links were constructed. [Copyright &y& Elsevier]

This paper describes and validates a novel framework using the Approximate Bayesian Computation (ABC) algorithm for parameter estimation and model selection in models of mesoscale brain network activity. We provide a proof of principle, first pass validation of this framework using a set of neural mass models of the cortico-basal ganglia thalamic circuit inverted upon spectral features from experimental, in vivo recordings. This optimization scheme relaxes an assumption of fixed-form posteriors (i.e. the Laplace approximation) taken in previous approaches to inverse modelling of spectral features. This enables the exploration of model dynamics beyond that approximated from local linearity assumptions and so fit to explicit, numerical solutions of the underlying non-linear system of equations. In this first paper, we establish a face validation of the optimization procedures in terms of: (i) the ability to approximate posterior densities over parameters that are plausible given the known causes of the data; (ii) the ability of the model comparison procedures to yield posterior model probabilities that can identify the model structure known to generate the data; and (iii) the robustness of these procedures to local minima in the face of different starting conditions. Finally, as an illustrative application we show (iv) that model comparison can yield plausible conclusions given the known neurobiology of the cortico-basal ganglia-thalamic circuit in Parkinsonism. These results lay the groundwork for future studies utilizing highly nonlinear or brittle models that can explain time dependant dynamics, such as oscillatory bursts, in terms of the underlying neural circuits. [ABSTRACT FROM AUTHOR]

In finite populations the action of neutral mutations is balanced by genetic drift, leading to a stationary distribution of alleles that displays a transition between two different behaviors. For small mutation rates most individuals will carry the same allele at equilibrium, whereas for high mutation rates of the alleles will be randomly distributed with frequencies close to one half for a biallelic gene. For well-mixed haploid populations the mutation threshold is μ c = 1 / 2 N , where N is the population size. In this paper we study how spatial structure affects this mutation threshold. Specifically, we study the stationary allele distribution for populations placed on regular networks where connected nodes represent potential mating partners. We show that the mutation threshold is sensitive to spatial structure only if the number of potential mates is very small. In this limit, the mutation threshold decreases substantially, increasing the diversity of the population at considerably low mutation rates. Defining k c as the degree of the network for which the mutation threshold drops to half of its value in well-mixed populations we show that k c grows slowly as a function of the population size, following a power law. Our calculations and simulations are based on the Moran model and on a mapping between the Moran model with mutations and the voter model with opinion makers. [ABSTRACT FROM AUTHOR]

Simulations of spatial interaction in archaeology have been successful in predicting the emergence of central sites, and political and economic hierarchies that match observed long-term settlement patterns. It still remains unclear, however, to what degree such models can effectively allow for uncertainty in the archaeological record, especially when it comes to incomplete and unevenly distributed settlement data, and how best they might incorporate artefact-scale evidence. This paper aims to address these issues, while attempting to tackle widely debated aspects of socio-political organisation and cultural interaction in the prehistoric Cretan landscape at the period immediately before and after the foundation of the first palace of Phaistos, one of the less well documented Bronze Age phases. We employ a simulation of spatial interaction inspired by approaches first developed in urban geography and combine this with regression-based predictive modelling to address the uncertainty introduced by missing settlements. We use evidence from artefact analysis partly to calibrate and partly to validate our model. We conclude that such an approach can contribute to more convincing archaeological theories about socio-political organisation, cultural affinity and regional identity by providing new evidence even in the presence of very fragmented data. [ABSTRACT FROM AUTHOR]

The extensive literature on sanctions has mainly focused on a dyadic interaction between sender and target. In contrast, this paper examines sanctions when the sender and target are embedded in a network of linkages to other agents. The sender can assemble a sanctioning coalition of neighbors to sever their links (execute multi-link cuts) to the target and her allies. Efficacy of sanctions is now crucially dependent on the network architecture. We characterize the structural properties of networks in which a sender can effectively sanction a target in the short run (when links can only be deleted) and the long run (when links can be both deleted and added). [ABSTRACT FROM AUTHOR]

Bibliometric indicators are used to characterize the research activity of institutions worldwide with production in the period 2003–2013 in journals that are indexed in Scopus's Food Science thematic category. Basic, normalized indicators were used to compare the institutions' performances, together with highly cited papers (top-10% and top-1%). An interactive map was generated, displaying the 645 institutions with at least 100 documents produced during this period. The greatest numbers of those institutions are in the United States, South Korea, Spain, and China. National collaboration networks were detected on the East and West Coasts of the United States, and in Canada, Ireland, France, Spain, Holland, Denmark, China, South Korea, Malaysia, Brazil, India, Argentina, and Nigeria. There was no significant research activity in many developing and food exporting countries located in sub-Saharan Africa, North and East Africa, the Middle East, Latin America, the Caribbean, Eastern Europe, Central Asia, and South East Asia. The need to take into account other criteria based on qualitative attributes and the inherent limitations in the bibliometric indicators are discussed. [ABSTRACT FROM AUTHOR]

Epilepsy is both a disease of the brain and the mind. Here, we present the first of two papers with extended summaries of selected presentations of the Third International Congress on Epilepsy, Brain and Mind (April 3–5, 2014; Brno, Czech Republic). Epilepsy in history and the arts and its relationships with religion were discussed, as were overviews of epilepsy and relevant aspects of social cognition, handedness, accelerated forgetting and autobiographical amnesia, and large-scale brain networks. [ABSTRACT FROM AUTHOR]

This paper explores how unequal resources and social and economic polarization affects the size of social networks and their use to access resources. We argue that individual resource position generates divergent expectations with regard to the impact of polarization on the size of networks on one hand, and their usefulness for accessing resources on the other. Social and economic polarization encourages reliance on informal networks, but those at the bottom of the social structure are forced to rely on more extensive networks than the wealthy to compensate for their isolated and underprivileged position. At the same time, social and economic polarization limits the resources the poor can access through their networks. We provide evidence consistent with these propositions, based on data derived from the International Social Survey Programme 2001 “Social Networks” dataset combined with contextual information on the levels of economic inequality in particular countries along with whether they experienced postcommunism. [ABSTRACT FROM AUTHOR]

Abstract: Network theory can be employed in two ways in archaeology: it can be used to analyse archaeological data, or it can be used to model a historical process for the purpose of simulating the data. This paper focuses on the first approach. In such analyses, similar archaeological contexts are often connected to form a similarity network. Similarity is treated as a proxy for social or causal relationships. Most often, similarity is defined by the presence of the same kind of find in two contexts. However, to detect relationships effectively, we have to allow any kind of similarity relation to be a criterion for connection, in which different kinds of attributes that characterise the contexts may be mixed. We discuss how such general similarity networks can be used to disclose relational patterns hidden in archaeological data. Statistical tests are necessary to distinguish significant patterns from random patterns. We argue that random permutation tests are well suited for this task, and we introduce appropriate tests of this kind. The methods outlined are compared to other kinds of quantitative data analysis, such as correspondence analysis. We discuss which approach is more suitable for which kind of data. The choice of approach also depends on the questions addressed to the archaeological material. [Copyright &y& Elsevier]

Abstract: Clustering is typically measured by the ratio of triangles to all triples regardless of whether open or closed. Generating clustered networks, and how clustering affects dynamics on networks, is reasonably well understood for certain classes of networks (Volz et al., 2011; Karrer and Newman, 2010), e.g. networks composed of lines and non-overlapping triangles. In this paper we show that it is possible to generate networks which, despite having the same degree distribution and equal clustering, exhibit different higher-order structure, specifically, overlapping triangles and other order-four (a closed network motif composed of four nodes) structures. To distinguish and quantify these additional structural features, we develop a new network metric capable of measuring order-four structure which, when used alongside traditional network metrics, allows us to more accurately describe a network׳s topology. Three network generation algorithms are considered: a modified configuration model and two rewiring algorithms. By generating homogeneous networks with equal clustering we study and quantify their structural differences, and using SIS (Susceptible-Infected-Susceptible) and SIR (Susceptible-Infected-Recovered) dynamics we investigate computationally how differences in higher-order structure impact on epidemic threshold, final epidemic or prevalence levels and time evolution of epidemics. Our results suggest that characterising and measuring higher-order network structure is needed to advance our understanding of the impact of network topology on dynamics unfolding on the networks. [Copyright &y& Elsevier]

Abstract: In this paper we study the problem of price competition and free entry in congested markets. In particular, we consider a network with multiple origins and a common destination node, where each link is owned by a firm that sets prices in order to maximize profits, whereas users want to minimize the total cost they face, which is given by the congestion cost plus the prices set by firms. In this environment, we introduce the notion of Markovian Traffic Equilibrium to establish the existence and uniqueness of a pure strategy price equilibrium, without assuming that the demand functions are concave nor imposing particular functional forms for the latency functions. We derive explicit conditions to guarantee existence and uniqueness of equilibria. Given this existence and uniqueness result, we apply our framework to study entry decisions and welfare, and establish that in congested markets with free entry, the number of firms exceeds the social optimum. [Copyright &y& Elsevier]

Abstract: Computational modeling can be a powerful tool for an experimentalist, providing a rigorous mathematical model of the system you are studying. This can be valuable in testing your hypotheses and developing experimental protocols prior to experimenting. This paper reviews models of seizures and epilepsy at different scales, including cellular, network, cortical region, and brain scales by looking at how they have been used in conjunction with experimental data. At each scale, models with different levels of abstraction, the extraction of physiological detail, are presented. Varying levels of detail are necessary in different situations. Physiologically realistic models are valuable surrogates for experimental systems because, unlike in an experiment, every parameter can be changed and every variable can be observed. Abstract models are useful in determining essential parameters of a system, allowing the experimentalist to extract principles that explain the relationship between mechanisms and the behavior of the system. Modeling is becoming easier with the emergence of platforms dedicated to neuronal modeling and databases of models that can be downloaded. Modeling will never be a replacement for animal and clinical experiments, but it should be a starting point in designing experiments and understanding their results. [Copyright &y& Elsevier]

Abstract: The modelling of past settlement and landscape structure from incomplete evidence is a well-established archaeological agenda. This paper highlights a model of spatial interaction and settlement evolution that has long been popular in urban geography and which was first applied to model historical settlement hierarchies some twenty-five years ago, but whose use since then for archaeological purposes has been very limited. Via a case study from Bronze Age Crete, we extend the analytical range of this model by suggesting ways in which it can (a) remain effective in the presence of missing data, (b) be given a stronger grounding in the physical landscape, and/or (c) be used to consider the evolutionary trajectory of settlements and physical routes over time. [Copyright &y& Elsevier]

Abstract: A substantial literature has found that religiosity is positively related to individuals’ civic engagement and informal helping behavior. Concurrently, social networks as sources of information and encouragement have been suggested as the mechanism underlying phenomena including successful job searches, improved health and greater subjective well-being. In this paper we use data from the Portraits of American Life Study (PALS) to examine whether religiously based social networks explain the well-established relationship between religion and civic engagement. We test potential mechanisms including beliefs, affiliation, and social networks, and we find that having a strong network of religious friends explains the effect of church attendance for several civic and neighborly outcomes. We suggest this phenomenon may exist in other, non-religious, spheres that also produce strong friendship networks. [Copyright &y& Elsevier]

Abstract: At its best, connectivity mapping can offer researchers great insight into how spatially disparate regions of the human brain coordinate activity during brain processing. A recent investigation conducted by Smith and colleagues (2011) on methods for estimating connectivity maps suggested that those which attempt to ascertain the direction of influence among ROIs rarely provide reliable results. Another problem gaining increasing attention is heterogeneity in connectivity maps. Most group-level methods require that the data come from homogeneous samples, and misleading findings may arise from current methods if the connectivity maps for individuals vary across the sample (which is likely the case). The utility of maps resulting from effective connectivity on the individual or group levels is thus diminished because they do not accurately inform researchers. The present paper introduces a novel estimation technique for fMRI researchers, Group Iterative Multiple Model Estimation (GIMME), which demonstrates that using information across individuals assists in the recovery of the existence of connections among ROIs used by Smith and colleagues (2011) and the direction of the influence. Using heterogeneous in-house data, we demonstrate that GIMME offers a unique improvement over current approaches by arriving at reliable group and individual structures even when the data are highly heterogeneous across individuals comprising the group. An added benefit of GIMME is that it obtains reliable connectivity map estimates equally well using the data from resting state, block, or event-related designs. GIMME provides researchers with a powerful, flexible tool for identifying directed connectivity maps at the group and individual levels. [Copyright &y& Elsevier]

Abstract: Using accumulated cost surfaces and various pathfinding techniques within Geographic Information Systems (GIS) software, archaeologists and other spatial scientists have developed increasingly sophisticated models of human movement. Despite their utility, these approaches can be limited because standard GIS software cannot model movement (1) from many origins to many destinations or (2) without specific origins and destinations. Absent these capabilities, it is particularly difficult to model networks of movement over a given tract of land if you are interested in obtaining a more general sense of movement dynamics, not specific site-to-site patterns. In this paper, we present an innovative way of modeling past movement that generates both natural-looking networks and also indicates the degree of traffic that may have existed on any particular segment of those networks. The “From Everywhere to Everywhere” (FETE) model generates networks based on topography and landcover without requiring that origin and destination points be supplied in advance. We apply the FETE model to a case from the southern Mexican state of Oaxaca, a region that has extensive archaeological and ethnohistoric data sets that serve as a test of the efficacy of our technique. A comparison of the FETE output with known late precolumbian and early colonial movement corridors indicates that the method is effective and should be useful for modeling networks in other areas. [Copyright &y& Elsevier]

Abstract: Some behaviors, ideas or technologies spread and become persistent in society, whereas others vanish. This paper analyzes the role of social influence in determining such distinct collective outcomes. Agents are assumed to acquire information from others through a certain sampling process, that generates an influence network, and they use simple rules to decide whether to adopt or not depending on the behavior of the observed sample. We characterize, as a function of the primitives of the model, the diffusion threshold (i.e., the spreading rate above which the adoption of the new behavior becomes persistent in the population) and the endemic state (i.e., the fraction of adopters in the stationary state of the dynamics). We find that an increase in the correlation between the out-degree (information level) and in-degree (visibility level) of agents may favor or harm diffusion; the effect actually depends on the specific details of the adoption process. [Copyright &y& Elsevier]

Abstract: This paper reports the results of an experimental investigation of dynamic games in networks. In each period, the subjects simultaneously choose whether or not to make an irreversible contribution to the provision of an indivisible public good. Subjects observe the past actions of other subjects if and only if they are connected by the network. Networks may be incomplete so subjects are asymmetrically informed about the actions of other subjects in the same network, which is typically an obstacle to the attainment of an efficient outcome. For all networks, the game has a large set of (possibly inefficient) equilibrium outcomes. Nonetheless, the network architecture makes certain strategies salient and this in turn facilitates coordination on efficient outcomes. In particular, asymmetries in the network architecture encourage two salient behaviors, strategic delay and strategic commitment. By contrast, we find that symmetries in the network architecture can lead to mis-coordination and inefficient outcomes. [Copyright &y& Elsevier]

Abstract: In this paper, we propose a discrete version of the following semilinear heat equation with absorption with , which is said to be the ω-heat equation with absorption on a network. Using the discrete Laplacian operator on a weighted graph, we define the ω-heat equations with absorption on networks and give their physical interpretations. The main concern is to investigate the large time behaviors of nontrivial solutions of the equations whose initial data are nonnegative and the boundary data vanish. It is proved that the asymptotic behaviors of the solutions as t tends to +∞ strongly depend on the sign of . [Copyright &y& Elsevier]

Abstract: Consciousness has been related to the amount of integrated information that the brain is able to generate. In this paper, we tested the hypothesis that the loss of consciousness caused by propofol anesthesia is associated with a significant reduction in the capacity of the brain to integrate information. To assess the functional structure of the whole brain, functional integration and partial correlations were computed from fMRI data acquired from 18 healthy volunteers during resting wakefulness and propofol-induced deep sedation. Total integration was significantly reduced from wakefulness to deep sedation in the whole brain as well as within and between its constituent networks (or systems). Integration was systematically reduced within each system (i.e., brain or networks), as well as between networks. However, the ventral attentional network maintained interactions with most other networks during deep sedation. Partial correlations further suggested that functional connectivity was particularly affected between parietal areas and frontal or temporal regions during deep sedation. Our findings suggest that the breakdown in brain integration is the neural correlate of the loss of consciousness induced by propofol. They stress the important role played by parietal and frontal areas in the generation of consciousness. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to extend the range of current analytical procedures that archaeologists use to understand movement. In particular, how a landscape becomes ordered by simply defining a destination. More specifically, this study proposes the derivation of a focal mobility network, i.e. the network of most likely paths towards a given destination, and explores several of its applications within a landscape archaeology framework. The suggested extensions are based on existing standard procedures within most GIS. A series of synthetic control surfaces and an archaeological study focused around Iron Age hillforts in Galicia (NW Spain) are used as case studies to illustrate different analytical possibilities. [Copyright &y& Elsevier]

Abstract: This paper focuses on the interaction between network structure, the role of information, and the level of trust and trustworthiness in 3-node networks. We extend the investment game with one Sender and one Receiver to networked versions — one characterized by one Sender and two Receivers ([1s-2r]) and one characterized by two Senders and one Receiver ([2s-1r]) — under two information conditions, full and partial. We develop a comparative model of trust for the networked exchange environments and generate two hypotheses: (1) what counts as a signal of trust depends on investment behavior along the other link in the network and (2) this type of trust can be leveraged under full information, increasing the rate of cooperation on the side of the exchange with multiple traders. The results generally support our hypotheses: trust is comparative and under full information, the [1s-2r] network shows higher trustworthiness and the [2s-1r] network displays higher trust. [Copyright &y& Elsevier]

Abstract: This paper proves the generic determinacy of Nash equilibrium in network-formation games: for a generic assignment of utilities to networks, the set of probability distributions on networks induced by Nash equilibria is finite. [Copyright &y& Elsevier]

Abstract: Rheology of sepiolite-based epoxy suspensions as well as morphology and dynamic mechanical properties of the corresponding nanocomposites are discussed in this paper. The influence of the type of sepiolite used, i.e. non-modified, aminosilane and glycidylsilane surface modified, and of the process developed to prepare the epoxy suspensions were investigated. Except for low amount of filler, a shear thinning behavior was observed in the others sepiolite-based epoxy suspensions. The interactions developed between the sepiolite and the epoxy matrix are responsible for the magnitude of the shear thinning effect and are related to the morphology of the nanocomposites. The best dispersion of sepiolite was achieved using either an emulsion process or a glycidyl functionalized sepiolite. [Copyright &y& Elsevier]

Abstract: The McCormick Harvesting Machine Co. displayed its harvesting machinery at world fairs and agricultural fairs, using these events to build respectability for its machines and in support of sales and advertising claims. Records of the company reveal the firm''s competitive behaviour at these fairs and their associated field trials for agricultural machinery. Analysis of company advertisements, catalogues, and correspondence on fairs and field trials reveals the way McCormick used these events, the extent and nature of international competition, and the nature of the world stage for industrial competition. Cyrus Hall McCormick, founder of the company, learning from his Crystal Palace success of 1851 and his even earlier experience with fairs in the USA, represented his reaper as a global product, made in America and internationally successful. Indeed, at the fairs McCormick''s machines were embroiled in internecine warfare among an international brotherhood of manufacturers in pursuit of common goals and using a common repertoire of tactics, if not identical machines. This is because ‘American harvesting machines’ were a trans-national phenomenon. The paper concludes that globalisation was occurring in harvesting machinery and suggests that problems emerge from considering international competition in this industry as a contest among distinct national economies. [Copyright &y& Elsevier]

Abstract: This paper explores the character, density and likely importance of connections between directors of a sample of 12 early-twentieth century British multinational companies. Drawing on the notion of ‘gentlemanly capitalism’, a reconstruction of multiple and interlocking directorships for 1899–1900 and 1929–1930 indicates that a complex network existed that comprised links, respectively, to 255 and 497 companies. We explore the social, cultural and political characteristics of the directors of our sample and argue that the ways in which members of this group interacted with each other would have influenced business attitudes, facilitated transfers of knowledge and promoted interdependencies, thereby shaping commercial behaviour. We argue that the directors of early multinationals formed the kind of definable ‘power geometries’ within the wider corporate elite that have been identified amongst today''s business elites. Our results indicate that a distinct and increasingly dynamic multinational corporate community existed in the early 1900s, which was in many respects like its modern counterparts. A key finding is that the complexity of dyadic connections between directors and their personal networks of contacts increased markedly between 1899–1900 and 1929–1930. [Copyright &y& Elsevier]

Abstract: Researchers have established that individual religiosity influences sexual behavior and that religious support can increase consistency between personal religiosity and behavior. Researchers are less certain, however, of the effect that religious friendship networks have on sexual behavior. In addition, the effects of network characteristics such as density and one’s position in a social network have not been established. This paper uses a network subsample of the National Longitudinal Study of Adolescent Health (Add Health) to examine the effect of friends’ religiosity on the probability of first sex. We find that friends’ religiosity has an independent influence on adolescent sexual behavior that is similar in magnitude to personal religiosity. We also find evidence that friends’ religiosity has the strongest influence on the sexual behavior of adolescents who are embedded in dense social networks, in which teens’ friends are also friends with one another. These results support the hypothesis that group influences depend on the degree of embeddedness within the network and highlight the importance of studying religion as a property of groups as well as individuals. [Copyright &y& Elsevier]

This paper develops a simple model to examine the interaction between partner choice and individual behavior in games of coordination. An important ingredient of our approach is the way we model partner choice: we suppose that a player can establish ties with other players by unilaterally investing in costly pairwise links. In this context, individual efforts to balance the costs and benefits of links are shown to lead to a unique equilibrium interaction architecture. The dynamics of network formation, however, has powerful effects on individual behavior: if costs of forming links are below a certain threshold then players coordinate on the risk-dominant action, while if costs are above this threshold then they coordinate on the efficient action. These findings are robust to modifications in the link formation process, different specifications of link formation costs, alternative models of mutations as well as the possibility of interaction among indirectly connected players. [Copyright &y& Elsevier]

Abstract: This paper describes the parallel implementation of a transport network model. ‘Single-Program, Multiple Data’ (SPMD) paradigm is employed using a simple data decomposition approach where each processor runs the same program but acts on a different subset of the data. The objective is to reduce the execution time of the model. The computationally intensive part of the model is within the assignment and simulation section and therefore this section is parallelised and executed using 1, 2, 4, 8 and 16 processors. The convergence, accuracy and performance of the parallel model are then assessed and compared to the linear implementation. The results indicate a performance increase of over 8 for the parallelised module and a speedup of 5 for the total model when the model is run using 16 processors. The efficiency, average parallelism and efficiency-execution time profile are also discussed. In the context of time savings with 16 processors compared with 1, the time saving on the IBM SP2 are of the order of 80%, and, compared to a linear implementation on a dual processor Intel machine are of the order of 86%. [Copyright &y& Elsevier]

In this paper, we consider a local public goods environment. The agents are faced with the task of providing local public goods that will benefit some or all of them. We propose a bidding mechanism whereby agents bid for the right to decide upon the organization of the economic activity. The subgame perfect equilibria of the mechanism generate efficient outcomes. We also show how to adapt the mechanism to network economies where the economic activity takes place via the formation of links. [Copyright &y& Elsevier]

Corporate innovation is often argued to result from, and be encouraged by, market competition. The tradition is to test such arguments with market concentration data; firms with stronger control over their market can afford the long-run investment of R&D. Network theory has broadened our understanding of how competition is a function of structure within and beyond a market. Producers earn high profit margins to the extent they are few and their customers and suppliers are many and disorganized. The first condition is measured by the traditional concentration ratio for a market. The second condition is measured by the network constraint of suppliers and customers. My purpose in this paper is to describe how our understanding of the market competition effect on innovation is enriched when the concentration measure of market competition tradition in economics is replaced with the network model of market competition now prevalent in sociology. Results indicate that markets facing competitive environments, in high constraint market positions, show greater R&D intensity and faster rates of innovation than do industries facing less competitive pressure. These effects persist even with controls for technological opportunity and appropriability, in contrast to traditional models using only concentration data to measure competition. [ABSTRACT FROM AUTHOR]