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We introduce a dynamic network formation model with incomplete information and asymmetric players who are partitioned into ordered groups. At each stage, a pair of players is randomly selected to update the link connecting them. The feature of the model is that the cost of a link depends on the distance between the labels of the groups players belong to. As a result, information about the other player's label is significant in the decision to form a link. Assuming incomplete information, players initially do not know each other's labels, but learn them upon being connected. Comparing the topologies of stable networks for cases of complete and incomplete information indicates that the presence of the latter can have deep implications. Furthermore, our simulation experiments are focused on three issues: the stabilization time, the heterogeneity index, and the impact of the group size gap. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In a social network in which friendly and rival bilateral links can be formed, how do alliances between decision-makers form, and what determines whether a conflict will arise? We study a network formation game between ex-ante symmetric players in the laboratory to examine the dynamics of alliance formation and conflict evolution. A peaceful equilibrium yields the greatest social welfare, while a successful bullying attack transfers the victimized player's resources evenly to the attackers at a cost. In within-subject and between-subject laboratory experiments, we find that the relative frequency of peaceful and bullying outcomes increases in the cost of attack. We further examine the dynamics leading to the final network and find that groups tend to coordinate quickly on a first target for attack, while the first attacker entails a non-negligible risk of successful counter-attack. These findings provide insights for understanding social dynamics in group coordination. [ABSTRACT FROM AUTHOR]

This paper studies a simple model inspired by the seminal connections model of Jackson and Wolinsky (1996). Node-players can invest in links to connect with other nodes forming networks, but only direct links transmit value. Nodes may have different values and different decreasing returns abilities/technologies to form/strengthen links. The strength of a link depends on the amounts invested in it by the two nodes that it connects and is determined by a separable function of the investments of the players which form the link. Nash-stable and efficient networks are characterized, and a variety of their architectures identified for different configurations of values and technologies. • Network formation with heterogeneity in nodes' values and in endogenous links. • Characterization of Nash and efficient networks. • Core–periphery, nested split graph and bipartite networks emergence. [ABSTRACT FROM AUTHOR]

Bolletta (2021) studies a model in which a network is strategically formed and then agents play a linear best-response investment game in it. The model is motivated by an application in which people choose both their study partners and their levels of educational effort. Agents have different one-dimensional types – private returns to effort. A main result claims that (pairwise Nash) stable networks have a locally complete structure consisting of possibly overlapping cliques: if two agents are linked, they are part of a clique composed of all agents with types between theirs. A counterexample shows that the claimed characterization is incorrect. We specify where the analysis errs and discuss implications for network formation models. [ABSTRACT FROM AUTHOR]

We show that the entry of formal financial institutions can have far-reaching and long-lasting impacts on informal lending and social networks more generally. We first study the introduction of microfinance in 75 villages in Karnataka, India, 43 of which were exposed to microfinance. Using difference-in-differences, we show that networks shrank more in exposed villages. Moreover, links between households that were both unlikely to borrow from microfinance were at least as likely to disappear as links involving likely borrowers. We replicate these surprising findings in the context of a randomised controlled trial (RCT) in Hyderabad, where a microfinance institution randomly selected 52 of 104 neighbourhoods to enter first. Four years after all neighbourhoods were treated, households in early-entry neighbourhoods had credit access longer and had larger loans. We again find fewer social relationships between households in these neighbourhoods, even among those ex-ante unlikely to borrow. Because the results suggest global spillovers, atypical in usual models of network formation, we develop a new dynamic model of network formation that emphasizes chance meetings, where efforts to socialize generate a global network-level externality. Finally, we analyse informal borrowing and the sensitivity of consumption to income fluctuations. Households unlikely to take up microcredit suffer the greatest loss of informal borrowing and risk sharing, underscoring the global nature of the externality. [ABSTRACT FROM AUTHOR]

The preparation of polythioethers has gained importance again after the development of click chemistry reactions. The thiol-X reactions, i.e., thiol-ene reactions based on free radical mechanism facilitated by light or heat, and thiol-Michael and thiol-epoxy reactions, which are the main synthetic pathways for the synthesis of polymers (linear, hyperbranched (HB), and network) with thioether linkages and meet most of the features of click reactions strategy, have currently been revisited. For a while, our group has focused on synthesizing linear, HB, and network polythioethers based on electron-deficient alkyne-containing precursors. We have shown that electron-deficient alkyne-containing monomers and polymers offer a suitable platform for thiol-Michael (i.e., thiol-yne) click reactions to yield linear, HB, and network structures rapidly under ambient conditions. The central structure in these polythioether syntheses is electron-deficient alkyne bonds of acetylenedicarboxylates, which are then reacted with dithiols in chloroform through an organobase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at ambient temperatures. Moreover, acetylenedicarboxylates are functionalized using copper-free azide-alkyne cycloaddition reaction followed by reacting with multifunctional allyl and SH derivatives through thiol-ene photopolymerization resulting in polymeric networks with thioether linkages. This feature article highlights our contribution to the synthesis of linear, HB, and network polythioether based on various electron-deficient alkyne precursors. [ABSTRACT FROM AUTHOR]

A standard policy to reduce the spread of infection is increasing the use of testing that enables the isolation of infected individuals, slowing down the infection. In "Testing, Voluntary Social Distancing, and the Spread of an Infection," the authors argue the possibility of unintended behavioral consequences from increased testing: greater testing reduces voluntary social distancing or increases social activity, exacerbating the spread of the virus. They show that the effect of testing on infections is nonmonotone. This nonmonotonicity also implies that the optimal testing policy may leave some of the testing capacity of society unused and that increasing testing should be used together with mandatory social distancing to reduce the spread of infection. We study the effects of testing policy on voluntary social distancing and the spread of an infection. Agents decide their social activity level, which determines a social network over which the virus spreads. Testing enables the isolation of infected individuals, slowing down the infection. However, greater testing also reduces voluntary social distancing or increases social activity, exacerbating the spread of the virus. We show that the effect of testing on infections is nonmonotone. This nonmonotonicity also implies that the optimal testing policy may leave some of the testing capacity of society unused. Funding: The authors acknowledge support from C3.DTI funding. Supplemental Material: The online appendix is available at https://doi.org/10.1287/opre.2021.2220. [ABSTRACT FROM AUTHOR]

This study investigates how people provide public goods in a network formation game. In this game, players form a network through bilateral linking, with or without a link cost; the players then contribute to a public good, which can benefit both themselves and their direct neighbors. Theoretically, two equilibrium goods provision strategies exist: splitting and alternation. Efficient networks are conditioned on a goods provision strategy and are less dense when the link cost increases. Our laboratory experiment indicates that subjects predominantly converge to splitting instead of alternation and can often form efficient networks. Subjects form fewer links under a higher link cost and tend to form too many links. [ABSTRACT FROM AUTHOR]

The Internet of Things – Low-Power and Lossy Networks (IoT-LLN) can operate with low power consumption and support reliable communication even in noisy and congested environments. Minimal 6TiSCH Configuration (6TiSCH-MC) and Routing Protocol for Low-Power and Lossy Networks (RPL) protocols bootstrap the IoT-LLN with minimum resources. The 6TiSCH and RPL protocols transmit different control messages for network bootstrapping and maintenance. The 6TiSCH-MC allows only a single minimal cell in each slotframe for transferring and receiving control messages. All network-associated nodes transmit their control messages simultaneously, using the same channel, which leads to collisions. Due to these control message collisions, new nodes waiting to associate with the network are not receiving the required control messages. It delays network formation, and nodes consume more energy. This research work proposes Two Minimal Cells with Dynamic ChannelOffset (TMDC) to overcome the bootstrapping issue of the 6TiSCH-MC. The TMDC increases the minimal cell count to two and provides mutual synchronization between parent and child nodes for transmitting and receiving control messages. The Contiki-NG's COOJA simulator was used for extensive simulation analysis. The TMDC bootstraps networks quicker with less energy and associates more nodes into the network than the 6TiSCH-MC. [ABSTRACT FROM AUTHOR]

Determining when team production is beneficial requires understanding how a team's characteristics affect its productive capabilities. This study proposes a model of team formation and production in which the number of teams established and the characteristics of each are determined by the structure of an endogenous network and synergies between team members. The results of a laboratory experiment, which varies the costs and benefits associated with forming teams, reveal that contributions to team production are generally in line with predictions despite considerable deviations in the team formation process. Overall, there are high rates of efficiency loss in the experiment, with groups obtaining less than half of the aggregate earnings possible, on average, and it is shown that this is largely attributable to sub-optimal network (team) formation. These findings indicate that self-formed teams are unlikely to be optimally constructed. • This study employs a networks approach to examine the endogenous formation of teams. • Contributions to team production are generally in line with theoretical predictions. • Deviations in the team formation process lead to high rates of inefficiency. • Self-formed teams are unlikely to be constructed in an optimal way. [ABSTRACT FROM AUTHOR]

Advice-seeking typically occurs across organizational boundaries through informal connections. By using Stochastic Actor-Oriented Models (SAOM), previous research has tried to identify the micro-level mechanisms behind these informal connections. Unfortunately, these models assume perfect network information, require agents to perform too cognitively demanding decisions, and do not account for threshold-based critical events, such as simultaneous tie changes. In the context of knowledge-intensive organizations, the shortage of high-skilled professionals could determine complex network effects given that many less-skilled professionals would seek advice from a few easily overloaded, selective high-skilled, who are also sensitive to status demotion. To capture these context-specific organizational features, we have elaborated on SAOM with an agent-based model that assumes local information, status-based tie selection, and simultaneous re-direction of multiple ties. By fitting our simulated networks to Lazega's advice network used in previous research, we reproduced the same set of macro-level network metrics with a parsimonious model based on more empirically plausible assumptions than previous research. Our findings show the advantage of exploring multiple generative paths of network formation with different models. • Preferences for ties with high-status advisors drive advice network formation. • We present a model that considers local information and status-related tie selection. • We fit Lazega advice network metrics as in previous research with simpler assumptions. [ABSTRACT FROM AUTHOR]

In any society, the relationship between economy and politics is characterized by controversy, enigmas and mysteries. Economic performance affects political results, and the political environment and its process produce financial results. Brazil was hit by economic and political crises from 2012 to 2016. Such crises made it possible to redesign the correlation network between the assets negotiated on the B3 (Brazil Stock Exchange and Over‐the‐Counter Market). This paper aimed to analyse the main aspects related to the topological structure of the assets negotiated on the B3 and its volatility between the pre‐and post‐2014 electoral periods. Results showed the hierarchical clusters and the evolution of the systemic risk, with the banks leading the concentration in the post‐electoral period. The closeness centrality indices for the minimum variance portfolios were modified by approximately 80% between the pre‐electoral and post‐electoral periods. It was concluded that the political events significantly changed the structure, the risk and the possibility of selecting assets for portfolios in the Brazilian market. [ABSTRACT FROM AUTHOR]

Copyright of Corporate Management Review is the property of College of Management, National Chiao Tung University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a parsimonious model of network formation with introductions in the presence of intermediation rents. Introductions allow two nodes to form a new connection on favorable terms with the help of a common neighbor. The decision to form links via introductions is subject to a trade-off between the gains from having a direct connection at lower cost and the potential losses for the introducer from lower intermediation rents. When nodes take advantage of introductions, stable networks tend to exhibit a minimum amount of clustering. At the same time, intermediary nodes have incentives to protect their position, and stable networks can exhibit nodes exploiting structural holes, that is, bridges across otherwise unconnected parts of the network earning intermediation rents. [ABSTRACT FROM AUTHOR]

When a founder cell and its progeny divide with incomplete cytokinesis, a network forms in which each intercellular bridge corresponds to a past mitotic event. Such networks are required for gamete production in many animals, and different species have evolved diverse final network topologies. Although mechanisms regulating network assembly have been identified in particular organisms, we lack a quantitative framework to understand network assembly and inter-species variability. Motivated by cell networks responsible for oocyte production in invertebrates, where the final topology is typically invariant within each species, we devised a mathematical model for generating cell networks, in which each node is an oscillator and, after a full cycle, the node produces a daughter to which it remains connected. These cell cycle oscillations are transient and coupled via diffusion over the edges of the network. By variation of three biologically motivated parameters, our model generates nearly all such networks currently reported across invertebrates. Furthermore, small parameter variations can rationalize cases of intra-species variation. Because cell networks outside of the ovary often form less deterministically, we propose model generalizations to account for sources of stochasticity. [ABSTRACT FROM AUTHOR]

Loss-of-function mutations in the contactin-associated protein-like 2 (CNTNAP2) gene are causal for neurodevelopmental disorders, including autism, schizophrenia, epilepsy, and intellectual disability. CNTNAP2 encodes CASPR2, a single-pass transmembrane protein that belongs to the neurexin family of cell adhesion molecules. These proteins have a variety of functions in developing neurons, including connecting presynaptic and postsynaptic neurons, and mediating signaling across the synapse. To study the effect of loss of CNTNAP2 function on human cerebral cortex development, and how this contributes to the pathogenesis of neurodevelopmental disorders, we generated human induced pluripotent stem cells from one neurotypical control donor null for full-length CNTNAP2 , modeling cortical development from neurogenesis through to neural network formation in vitro. CNTNAP2 is particularly highly expressed in the first two populations of early-born excitatory cortical neurons, and loss of CNTNAP2 shifted the relative proportions of these two neuronal types. Live imaging of excitatory neuronal growth showed that loss of CNTNAP2 reduced neurite branching and overall neuronal complexity. At the network level, developing cortical excitatory networks null for CNTNAP2 had complex changes in activity compared with isogenic controls: an initial period of relatively reduced activity compared with isogenic controls, followed by a lengthy period of hyperexcitability, and then a further switch to reduced activity. Complete loss of CNTNAP2 contributes to the pathogenesis of neurodevelopmental disorders through complex changes in several aspects of human cerebral cortex excitatory neuron development that culminate in aberrant neural network formation and function. [ABSTRACT FROM AUTHOR]

We study a coevolutionary model of network formation in minimum-effort games. Agents dynamically choose both their effort levels and their interaction partners, but face heterogeneous constraints on how many partners they can interact with. The dynamics under heterogeneity behaves very differently from the one in the homogeneous case, with gradual transitions spreading across the population stepwise instead of sudden adoptions. The long-run outcomes depend crucially on the distribution of interaction constraints. The efficient (highest-effort) convention prevails in the long run even when many agents have loose constraints, if enough agents have tight constraints. The lowest-effort convention dominates if too many agents have loose constraints. The coexistence of conventions is also possible for certain distributions of constraints. [ABSTRACT FROM AUTHOR]

This study aims to identify the driving forces behind interorganizational networks in China following disasters. Using the theory of complex adaptive systems, we identified the self‐organization process of disaster response as the network formation process. We identified interorganizational networks that emerged in response to two natural hazards and two technical disasters by collecting data from multiple sources. The exponential random model analysis is performed to analyze the effects of structures and organizational attributes on network formation. In structuring networks for disaster response, findings demonstrate that bonding structures take precedence over bridging structures for organizations. Meanwhile, the sector and jurisdiction‐based homophily effects facilitate network formation in disaster response. On the basis of research findings, five propositions describing the network formation process in China's disaster response are proposed. Such a theoretical model is essential for advancing research and practice in complex disaster network management. [ABSTRACT FROM AUTHOR]

Abstract Many industrial components, especially those realized through 3D printing undergo surface finishing processes, predominantly, in the form of mechanical polishing. The polishing processes for custom components remain manual and iterative. Determination of the polishing endpoints, i.e., when to stop the process to achieve a desired surface finish, remains a major obstacle to process automation and in the cost-effective custom/3D printing process chains. With the motivation to automate the polishing process of 3D printed materials to a desired level of surface smoothness, we propose a dynamic model of surface morphology evolution of 3D printed materials during a polishing process. The dynamic model can account for both material removal and redistribution during the polishing process. In addition, the model accounts for increased material flow due to heat generated during the polishing process. We also provide an initial random surface model that matches the initial surface statistics. We propose an optimization problem for model parameter estimation based on empirical data using KL-divergence and surface roughness as two metrics of the objective. We validate the proposed model using data from polishing of a 3D printed sample. The procedures developed makes the model applicable to other 3D printed materials and polishing processes. We obtain a network formation model as a representation of the surface evolution from the heights and radii of asperities. We use the network connectivity (Fiedler number) as a metric for surface smoothness that can be used to determine whether a desired level of smoothness is reached or not. [ABSTRACT FROM AUTHOR]

Independently addressing photoreactive sites within one molecule with two colours of light is a formidable challenge. Here, we combine two sequence independent λ‐orthogonal chromophores in one heterotelechelic dilinker molecule, to exploit their disparate reactivity utilizing the same reaction partner, a maleimide‐containing polymer. We demonstrate that polymer network formation only proceeds if two colours of light are employed. Upon single colour irradiation, linker‐decorated post‐functionalized polymers are generated at either wavelength and in either sequence. Network formation, however, is only achieved by sequential or simultaneous two colour irradiation. The herein introduced photoreactive system demonstrates the power of wavelength orthogonal chemistry in macromolecular synthesis. [ABSTRACT FROM AUTHOR]

Competition in research has led to the emergence of new regional spaces and interorganizational arrangements, designed to improve their participants' visibility, at the crossroads of regional systems and global exchanges. This article investigates the determinants of the formation of interregional scientific alliances through the in-depth case study of a federation of research laboratories in green chemistry in western France. Working from bibliometric and qualitative data and using a network analysis approach to evidence interurban network failures in this scientific field, we examine the federation's geographical scope. We highlight the decisive role of (1) the spatial organization of the field (structure effect), (2) interpersonal ties between consortium members (network effect) and (3) national scientific guidelines and incentives (policy effect). We propose a novel mixed-method approach to understand interregional alliances and defend its potential to uncover the importance of interregional institutional arrangements in prompting interurban knowledge exchanges. [ABSTRACT FROM AUTHOR]

We model the formation of networks as the result of a game where by players act selfishly to get the portfolio of links they desire most. The integration of player strategies into the network formation model is appropriate for organizational networks because in these smaller networks, dynamics are not random, but the result of intentional actions carried through by players maximizing their own objectives. This model is a better framework for the analysis of influences upon a network because it integrates the strategies of the players involved. We present an Integer Program that calculates the price of anarchy of this game by finding the worst stable graph and the best coordinated graph for this game. We simulate the formation of the network and calculated the simulated price of anarchy, which we find tends to be rather low. [ABSTRACT FROM AUTHOR]

We consider a model of social coordination and network formation where agents decide on an action in a coordination game and on whom to form costly links with. We explore the role of linking friction, where an agent cannot change all of her links simultaneously when choosing an alternative linking decision. Given linking friction, interaction structures are not fully flexible. We introduce a new solution concept of static equilibria, local Nash equilibria, and find that the set of local Nash equilibria may include action-heterogenous strategy profiles. Furthermore, risk-dominant strategy profiles are stochastically stable when linking friction is restrictive, and payoff-dominant strategy profiles are stochastically stable when linking friction becomes less restrictive. More importantly, linking friction can greatly accelerate the emergence of payoff-dominant strategy profiles. [ABSTRACT FROM AUTHOR]

Strategic complementarities influence various social and economic activities. This study introduces a model to design a weighted and directed complementarity network to achieve a planner's objectives. The network represents the direction and intensity of complementarities between agents, influencing their best-responses to one another and determining equilibrium efforts. The planner's objective function can be convex, as commonly assumed in prior research, or arbitrarily concave to represent scenarios with diminishing marginal returns to each agent's effort. In all scenarios, optimal networks are generalized nested split graphs (GNSGs) which exhibit a link-dominance hierarchy among agents. These optimal networks are often strictly hierarchical, leading to inequality between ex ante identical agents. Additional analysis of a non-cooperative network formation game reveals that all decentralized equilibrium networks are inefficient GNSGs. [ABSTRACT FROM AUTHOR]

How to Avoid Polarization in Social Networks In order to facilitate social interactions and the design of deliberative and efficient institutions, a social planner should ensure that diverse opinions can be sustained and debated and ensuring social cohesion. Grabisch et al. provide a theory of the efficient design of public debate. They develop a model of the coevolution of opinions and social relations that allow them to frame this problem in a formal setting. This model of opinion dynamics accounts for the persistence of heterogeneous opinions in society ("strong diversity") and the dynamic interactions between opinions and social connections. The social planner faces a trade-off between fostering the convergence of opinions in society and increasing the risk of polarization and instability. To resolve this trade-off, the social planner must account for both structural and behavioral characteristics: how fragile is the social network and to what extent individuals tolerate disagreement with their peers. We propose a model of the joint evolution of opinions and social relationships in a setting in which social influence decays over time. The dynamics are based on bounded confidence: social connections between individuals with distant opinions are severed, whereas new connections are formed between individuals with similar opinions. Our model naturally gives rise to strong diversity, that is, the persistence of heterogeneous opinions in connected societies, a phenomenon that most existing models fail to capture. The intensity of social interactions is the key parameter that governs the dynamics. First, it determines the asymptotic distribution of opinions. In particular, increasing the intensity of social interactions brings society closer to consensus. Second, it determines the risk of polarization, which is shown to increase with the intensity of social interactions. Our results allow us to frame the problem of the design of public debates in a formal setting. We, hence, characterize the optimal strategy for a social planner who controls the intensity of the public debate and, thus, faces a trade-off between the pursuit of social consensus and the risk of polarization. We also consider applications to political campaigning and show that both minority and majority candidates can have incentives to lead society toward polarization. Funding: The authors acknowledge financial support from the European Union's Horizon 2020 research and innovation program [Grants 721846, "Expectations and Social Influence Dynamics in Economics (ExSIDE)" and 956107 "Economic Policy in Complex Environments"]. A. Mandel acknowledges support from the European Union's Horizon 2020 research and innovation program [Grants 884565, "Enabling Positive Tipping Points Toward Clean-Energy Transitions in Coal and Carbon Intensive Regions"]. [ABSTRACT FROM AUTHOR]

We study a model of innovation with a large number of firms that create new technologies by combining several discrete ideas. These ideas are created via private investment and spread between firms. Firms face a choice between secrecy, which protects existing intellectual property, and openness, which facilitates learning from others. Their decisions determine interaction rates between firms, and these interaction rates enter our model as link probabilities in a learning network. Higher interaction rates impose both positive and negative externalities, as there is more learning but also more competition. We show that the equilibrium learning network is at a critical threshold between sparse and dense networks. At equilibrium, the positive externality from interaction dominates: the innovation rate and welfare would be dramatically higher if the network were denser. So there are large returns to increasing interaction rates above the critical threshold. Nevertheless, several natural types of interventions fail to move the equilibrium away from criticality. One effective policy solution is to introduce informational intermediaries, such as public innovators who do not have incentives to be secretive. These intermediaries can facilitate a high-innovation equilibrium by transmitting ideas from one private firm to another. [ABSTRACT FROM AUTHOR]

We study a model of over-the-counter trading in which ex ante identical traders invest in a contact technology and participate in bilateral trade. We show that a rich market structure emerges both in equilibrium and in an optimal allocation. There is continuous heterogeneity in market access under weak regularity conditions. If the cost per contact is constant, heterogeneity is governed by a power law and there are middlemen, market participants with unboundedly high contact rates who account for a positive fraction of meetings. Externalities lead to overinvestment in equilibrium, and policies that reduce investment in the contact technology can improve welfare. We relate our findings to important features of real-world trading networks. [ABSTRACT FROM AUTHOR]

We examine the statistical and dynamic properties of board networks connected through interlocking directorates. We find that the degree distribution of a board network follows a power-law distribution. Furthermore, the evolution of the core–periphery structure of board networks over time is related to market stability. This result implies that firms, when densely connected to other boards, would like to keep their position as core groups in board networks. Firm value shows a statistically positive relationship with firms centrally positioned in a board network. Overall, we suggest that board networks can help us understand market stability and serve as an alternative information channel for increasing the firm value. These findings imply that the statistical and dynamic properties of board networks uncover information transmission during the global financial crisis. This paper contributes to interdisciplinary applications of physics in economics and finance in terms of the dynamics of a core–periphery structure of board networks.

The rheological and mechanical properties of elastomers are defined by their different networks: The crosslink network and the filler network. The crosslink network is influenced by the polymer structure. The filler network – particularly in case of silica as filler – depends on the interaction between the filler particles and the polymer. Liquid polymers can affect these networks by their lower molecular weight and with certain types by their functional groups. The goal of the present work is to gain a better understanding of the network formation: 1. During the sulfur curing of pure liquid polybutadienes with different concentrations of sulfur and curatives, and 2. Through differently added liquid polymer-silica-masterbatches in sulfur cured silica/SSBR mixtures. For the first point, the pre-cured liquid polymer samples were analyzed by gel permeation chromatography. The results indicate an association between weight concentration and the polymer chain length. For the second point, stress-strain analysis according to Mooney-Rivlin provides information about the interaction of liquid polymers with silica and the main polymer when it is added differently throughout the masterbatch approach.

The study of network formation is pervasive in economics, sociology, and many other fields. In this article, we model network formation as a 'choice' that is made by nodes of a network to connect to other nodes. We study these 'choices' using discrete-choice models, in which agents choose between two or more discrete alternatives. We employ the 'repeated-choice' (RC) model to study network formation. We argue that the RC model overcomes important limitations of the multinomial logit (MNL) model, which gives one framework for studying network formation, and that it is well-suited to study network formation. We also illustrate how to use the RC model to accurately study network formation using both synthetic and real-world networks. Using edge-independent synthetic networks, we also compare the performance of the MNL model and the RC model. We find that the RC model estimates the data-generation process of our synthetic networks more accurately than the MNL model. Using a patent citation network, which forms sequentially, we present a case study of a qualitatively interesting scenario—the fact that new patents are more likely to cite older, more cited, and similar patents—for which employing the RC model yields interesting insights. [ABSTRACT FROM AUTHOR]

Studies on network formation employ rather different assumptions on link formation and make different predictions. We propose a constant elasticity of substitution (CES) link formation specification that generalizes commonly used link formation assumptions and parametrizes a factor that could affect network formation, namely, link investment substitutability (LIS). We apply this approach to the model by Galeotti and Goyal (2010) that studies public good provision on an endogenously formed network and find that results on equilibria differ significantly depending on whether link investments are substitutes or complements. Additionally, when link investments are complements, we find that LIS governs the unequalness of equilibrium structures. We also explore how LIS influences the relationship between the public good provision of a player and her utility. [ABSTRACT FROM AUTHOR]

A long-lasting open question in the literature of strategic network formation is the characterization of nonminimal Nash networks in the context of twoway ow model with nonrival information. In this note, I provide a partial answer to this question for the class of nonminimal networks such that every chain between two agents has the length of at most two and heterogeneity in information value possessed by each agent is assumed. I show that every strict Nash network is a strongly nested split graph. I also show that every strict Nash network is also efficient given a specific structure of information value. [ABSTRACT FROM AUTHOR]

We examine a model of network formation in single-layer and multiplex networks in which individuals have positive incentives for social ties, closed triangles, and spillover edges. In particular, we investigate the influence of shocks to the network in which the cost of social ties changes after an initial equilibrium. We highlight the emergence of structural entrenchment: the retention of structural features, such as closed triangles and spillover edges, which are formed under historically different conditions from those currently driving network evolution. This work has broad implications for understanding path dependence in the structure and dynamics of single-layer and multiplex networks.

Various contents of graphene nanoplatelets (GNPs), ranging from 0 to 0.7 wt%, with an efficient solvent method were used to reinforce flax/epoxy composites and thereby correlate GNPs network formation with the degree of reinforcement in resultant nanocomposites. The microstructural features characterised by wide X-ray diffraction (WAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) determined a correlation between GNPs reinforcing efficiency, nanolayers network formation and the number of layers. TEM analysis clarified that with a change in GNPs content, the distribution of nanolayers transformed from a zonal distribution to efficiently bridged networks contributing to maximum improvement in tensile and flexural properties at 0.5 wt% of GNPs. This was supported by morphological observations developed by SEM confirming various reinforcing mechanisms thanks to GNPs networks leading to enhanced interfacial adhesion between fibre and matrix. Likewise, with formation of networks, crack length at the interface of fibre and matrix and crack density in nanocomposites, determined from optical microscopy images of tensile-tested samples, received a significant decrease. TEM observations also proved that plane-to-plane and edge-to-edge contact areas of GNPs had paramount influences on reinforcement efficiency in nanocomposites. Exceeding the optimum content (0.5 wt%), the load transfer capability induced by GNPs network formation was adversely affected by plane-to-plane contacts of GNPs eventually leading to substantial reductions in mechanical properties. In drop weight impact analysis, GNPs networks also enhanced crack initiation energy and consequently reduced crack propagation energy and damage area in nanocomposites.

In this research article, we introduce a methodology we developed in order to collect and analyze data from 42 Spanish-language magazines which were published between 1891 and 1936. The example of the imagery found in these magazines will be used here to illustrate some of the research findings which came out of the project “Cultural Magazines from Modernismo to Avantgarde: Processes of Modernization and Transnational Networks”. In this project, the focus was both on network formation and on the transnational exchanges established by the cultural magazines examined. Analysis is performed by establishing bimodal networks that enable the examination of transatlantic transfers between Europe and Hispanic America. Beyond the question of transfers, major insights from the project are presented, such as the observation that in the cultural field, taste dominates and limits the number of possible connections between contributors and magazines. The limitations of the chosen methodology lie in the explanatory power of centrality measures applied to bimodal networks, which provide questionable results with respect to relevant research questions. As a remedy, we propose the use of a ‘cultural transfer rate’ which can be calculated from the data established within the project. While this research project focused on the cultural exchanges facilitated by Spanish-language magazines, further research avenues that can be explored in the future, on the basis of the data provided by the project, are also discussed. The first of these avenues consists of transforming the data at hand into one-mode social networks, which would enable the analysis of the social dimensions relevant to the material, especially with regard to groups of artists and the synergies created within them. The second avenue describes how the aggregation of further data would enable researchers to trace the trajectories of individuals within the network and determine their accumulation of symbolic capital.

Objectives: To explore historical and contemporary factors and processes that influenced the emergence of WANEL and analyse how the formation process has influenced the network’s continued existence and sustainability and lesson for sub-regional health policy and systems research (HPSR) networking in Low –and –Middle –Income Countries (LMICs) Design: Qualitative explanatory case study which used process tracing to chart the formation and development of WANEL. Methods: Data was obtained through document reviews, semi-structured interviews, group discussions, and participant observation. Data was analysed using thematic content analysis. Results: The emergence of WANEL was made possible by several factors, including support from a network of senior HPSR champions and institutions across West Africa; sustained funding from IDRC Canada, a reputable funder with a track record in supporting research capacity development in LMICs; learning and networking opportunities provided by CHEPSAA Emerging Leaders and the Institute of Tropical Medicine Antwerp Emerging Voices for Global Health initiative. Its formation followed a mix of emergent and engineered processes. Conclusion: WANEL is the first and currently the only sub-regional network for early and mid-career health policy and systems researchers and practitioners in West Africa. To ensure its long-term sustainability, the network needs to put in place mechanisms to constantly attract and develop the next generation of early and mid-career researchers, maintain links with senior researchers, strengthen its capacity for coordination and facilitation, and develop a plan for its long-term financial sustainability. [ABSTRACT FROM AUTHOR]

We consider a model where players can actively form a limited number of links with other players to play a general class of size-dependent coordination games. This class of games includes multi-person binary action coordination games, minimum effort games, average opinion games, and others, and it is mainly characterized by strategic complementarities among actions. Whenever players may only support links to a relatively small number of other players, the most efficient convention will be selected, irrespective of the details of the size-dependent coordination games. When the linking constraint becomes less restrictive, the most efficient convention will still be selected, provided that the most efficient action delivers a relatively high output when played against a small group also using it. Furthermore, for the special case of size-dependent minimum effort games, the second most efficient convention may be selected. [ABSTRACT FROM AUTHOR]

Fueled by recent advances in statistical modeling and the rapid growth of network data, social network analysis has become increasingly popular in sociology and related disciplines. However, a significant amount of work in the field has been descriptive and correlational, which prevents the findings from being more rigorously translated into practices and policies. This article provides a review of the popular models and methods for causal network analysis, with a focus on causal inference threats (such as measurement error, missing data, network endogeneity, contextual confounding, simultaneity, and collinearity) and potential solutions (such as instrumental variables, specialized experiments, and leveraging longitudinal data). It covers major models and methods for both network formation and network effects and for both sociocentric networks and egocentric networks. Lastly, this review also discusses future directions for causal network analysis. [ABSTRACT FROM AUTHOR]

Biopolymer networks play a major role as part of the cytoskeleton. They provide stable structures and act as a medium for signal transport. These features encourage the application of such networks as organic computation devices. While research on this topic is not advanced yet, previous results are very promising. The protein actin in particular appears advantageous. It can be arranged to various stable structures and transmit several signals. In this study aster shaped networks were self-assembled via entropic forces by the crowding agent methyl cellulose. These networks are characterised by a regular and uniquely thick bundle structure, but have so far only been accounted in droplets of 100 μm diameter. We report now regular asters in an area of a few mm2 that could be observed even after months. Such stability outside of an organism is striking and underlines the great potential actin aster networks display.

This study considers a network formation model in which each dyad of agents strategically determines the link status. Our model allows the agents to have unobserved group heterogeneity in the propensity of link formation. For the model estimation, we propose a three-step maximum likelihood method, in which the latent group structure is estimated using the binary segmentation algorithm in the second step. As an empirical illustration, we focus on the network data of international visa-free travels. The results indicate the presence of significant strategic complementarity and a certain level of degree heterogeneity in the network formation behavior. [ABSTRACT FROM AUTHOR]

The ability of light to remotely control the properties of soft matter materials in a dynamic fashion has fascinated material scientists and photochemists for decades. However, only recently has our ability to map photochemical reactivity in a finely wavelength resolved fashion allowed for different colors of light to independently control the material properties of polymer networks with high precision, driven by monochromatic irradiation enabling orthogonal reaction control. The current concept article highlights the progress in visible light‐induced photochemistry and explores how it has enabled the design of polymer networks with dynamically adjustable properties. We will explore current applications ranging from dynamic hydrogel design to the light‐driven adaptation of 3D printed structures on the macro‐ and micro‐scale. While the alternation of mechanical properties via remote control is largely reality for soft matter materials, we herein propose the next frontiers for adaptive properties, including remote switching between conductive and non‐conductive properties, hydrophobic and hydrophilic surfaces, fluorescent or non‐fluorescent, and cell adhesive vs. cell repellent properties. [ABSTRACT FROM AUTHOR]

This paper develops a model that captures which contracts are signed and on what terms in a market with a network of firms. This paper develops a model of vertical markets with multiple upstream and downstream firms. Networks of vertical relationships, negotiated contract terms for those relationships, and downstream prices charged to end customers all arise endogenously. In addition, I provide an estimation procedure to fully rationalize the observed network and contracts in a computationally scaleable manner. I empirically apply the framework to the market between hospitals and health insurers. I use the model to quantify the effects of "network adequacy regulations," which are designed to broaden patients' hospital choice sets but can backfire by increasing prices. I show that "tight" regulations have adverse effects. I also show market response is substantially impacted by complex mechanisms involving the interplay among multiple insurers and between upstream negotiation and downstream pricing. [ABSTRACT FROM AUTHOR]

The 6TiSCH standard provides minimum latency and reliability in mission-critical IoT applications. To optimize resource allocation during 6TiSCH network formation, IETF released the 6TiSCH minimal configuration (6TiSCH-MC) standard. 6TiSCH-MC considered IETF’s IPv6 Routing Protocol for Low power and Lossy network (RPL) as a routing protocol for both upward and downward routing. In RPL, new joining nodes or joined nodes transmit DODAG Information Solicitation (DIS) requests to get routing information from the network. However, we observe that malicious node(s) can severely affect 6TiSCH networks by sending multiple DIS requests. In this letter, we show and experimentally evaluate on real devices the impact of the DIS attack during 6TiSCH networks formation. We show that the attacker does not need expensive resources or access to the network’s sensitive information to execute the DIS attack. Our testbed experiments show that the DIS attack significantly degrades the nodes’ joining time and energy consumption, increasing them by 34% and 16%, respectively, compared to normal functioning during 6TiSCH network formation. [ABSTRACT FROM AUTHOR]