Clubs in an urban setting

In this paper the properties of a congestable concentrated local public good (CCoLPG) are described, taking into account both locational aspects and congestion. This discussion, therefore, completes the analysis of congestable local public goods (LPG) which was started in our earlier paper (Congestable local public goods in an urban setting, J. Urban Econ., 290–310 (1982). It is here shown that the optimal provision of CCoLPG leads to the creation of clubs, where the government has to determine the location and provide the optimal quantity of LPG in each club and also levy congestion tolls on users according to their level of utilization of the club. Congestion tolls cover the αest part of the costs, where α is the level of congestability of the CCoLPG. The rest of the costs are covered by taxing land rents. Clubs will form, possibly more than one per city, even if the LPG is pure (i.e., α = 0) and they will contain a single household if the LPG is private (i.e., α = 1). The difference between these results and those of classical club theorists stem from the fact that here we also take into account the limited supply of land of given accessibility (i.e., locational aspects), which like congestion lead to the creation of clubs. When these two factors are considered together, it explains why congestion tolls alone are not sufficient to finance clubs' operations, or why pure LPGs also have to be provided locally, etc.     

Beyond Circular Thinking: Geographies of Transit‐Oriented Development

Transit‐oriented development (TOD) plays a significant role within contemporary planning policies for ‘smart growth’ and sustainable development, particularly in Europe and North America. As a well‐rehearsed practice, this planning model is due for critical assessment and improvement in terms of its ability to incorporate dynamic and heterogeneous socio‐spatial processes as matters of concern. Analyses of the conditions for ‘making TOD work’ in the scholarly and professional literatures tend to focus on the ‘node’ and ‘place’ qualities. While elaborations on node analysis (primarily based on accessibility measurements) abound within empirical research, discussions of place‐specific assets are limited in scope and often spatially bounded by the circle defined by a 10‐minute walk. This essay examines the use of this generic ‘circle’ model, and how it normatively frames how place is understood in TOD studies. We argue that the circle enhances a Euclidean understanding of the site, which favours a static and homogeneous spatial analysis of accessibility and density rather than (other) place qualities relating to dynamic socio‐spatial processes. Finally, we argue that relational geography can facilitate an analysis of place qualities beyond the circle—one in which both the continuities and shifting settings of the wider context are meaningfully taken into consideration.     

The influence of supply network structure on firm innovation

In this study, we examine the structural characteristics of supply networks and investigate the relationship between a firm's supply network accessibility and interconnectedness and its innovation output. We also examine potential moderating effects of absorptive capacity and supply network partner innovativeness on innovation output. We hypothesize that firms will experience greater innovation output from (1) higher levels of supply network accessibility and supply network interconnectedness, (2) the interaction between the levels of these two structural characteristics, (3) the moderating role of absorptive capacity on supply network accessibility and the moderating role of supply network partner innovativeness on supply network interconnectedness. Supply network partner relationships are drawn in the context of the electronics industry using data from multiple sources. We use social network analysis to create measures for each supply network structural characteristic. Using regression techniques to test the relationship between these structural characteristics and firm innovation for a sample of 390 firms, our findings suggest that supply network accessibility has a significant association with a firm's innovation output. The results also indicate that interconnected supply networks strengthen the association between supply network accessibility and innovation output. Moreover, the influence of the two structural characteristics on innovation output can be enhanced by a firm's absorptive capacity and level of supply network partner innovativeness. By addressing the need for deeper structural analysis, this study contributes to supply chain research by accounting for the embedded nature of ties in supply networks, and showing how these structural characteristics influence the knowledge and information flows residing within a firm's supply network.     

The effects of high-speed rail on accessibility and equity: Evidence from the Turin-Lyon case-study

According to EU directives, cost-benefit analysis (CBA) is adopted to assess the impacts of high-speed rail (HSR). CBA evaluates the effectiveness of such infrastructure, determining whether and to what extent the present benefits overcome the present opportunity costs. However, it fails to include equity issues, which are the key aspects of transport planning. After a general discussion of equity in HSR and its link with the concept of accessibility, this study describes some complementary methods to calculate the variation in equity. Four of them (i.e. the potential accessibility index, spatial rail equity index, Gini index, and coefficient of variation) were adopted to assess the equity impacts for the Italian municipalities along the Turin-Lyon HSR. The results of the analysis reveal that despite a generalised increase in overall accessibility, equity implications are more contradictory, with main localities gaining further benefits compared to medium- and small-sized municipalities. In particular, the latter register a further increase in peripheralization. However, since they account for 36% of the total surface but represent only approximately 1% of the total population, the overall balance for the population served by the infrastructure may be considered positive. These results are particularly useful in contexts where the acceptance of HSR is weak, as they allow policymakers to identify adequate compensation measures to reduce the gap and increase territorial cohesion.     

Classification of various attacks and their defence mechanism in online social networks: a survey

Due to the popularity and user friendliness of the Internet, numbers of users of online social networks (OSNs) and social media have grown significantly. However, globally utilised, social networks are the consequence of the lack of understanding of secrecy and protection on OSN and media has increased. Secrecy and surety of OSNs need to be inquired from various positions. According to recent studies, OSN users expose their private information such as email address, phone number etc. In this paper, we have presented a high-level classification of recent OSN attacks for recognising the problem and analysing the blow of such attacks on World Wide Web. We have also discussed OSN attacks on different social networking web applications by citing certain recent reports such as Kaspersky security network and Sophos security threat report. We also offer some simple-to-implement user practice tips to protect the system and user’s information. In addition to this, we have discussed a comprehensive analysis of numerous defensive approaches on OSN security. Lastly, based on the acknowledged strength and faults of these defensive approaches, we have explained open research issues.     

Spatial social networks

We introduce a spatial cost topology in the network formation model analyzed by Jackson and Wolinsky, Journal of Economic Theory (1996), 71: 44–74. This cost topology might represent geographical, social, or individual differences. It describes variable costs of establishing social network connections. Participants form links based on a cost-benefit analysis. We examine the pairwise stable networks within this spatial environment. Incentives vary enough to show a rich pattern of emerging behavior. We also investigate the subgame perfect implementation of pairwise stable and efficient networks. We construct a multistage extensive form game that describes the formation of links in our spatial environment. Finally, we identify the conditions under which the subgame perfect Nash equilibria of these network formation games are stable. We are very grateful for the constructive comments of Matt Jackson and an anonymous referee. We also like to thank Vince Crawford, Marco Slikker, Edward Droste, Hans Haller, Dimitrios Diamantaras, and Sudipta Sarangi for comments on previous drafts of this paper.We acknowledge Jay Hogan for his programming support. Part of this research was done while visiting the CentER for Economic Research, Tilburg University, Tilburg, The Netherlands.Financial support from the Netherlands Organization for Scientific Resrarch (NWO), grant B46-390, is gratefully acknowledged.-->,     

Including deprivation costs in facility location models for humanitarian relief logistics

Humanitarian assistance is meant to save lives and alleviate human suffering during and in the aftermath of man-made and natural disasters. To prevent and strengthen preparedness for the occurrence of such situations, having available relief supplies in the short-term becomes crucial. The lack of access to life-sustaining items implies a loss in people's welfare, treated as an externality called deprivation costs which must be incorporated into decision-making processes. Since typical humanitarian applications are extensions of commercial logistic models, they usually do not account for externalities, leading to high social costs and likely to unfeasible or suboptimal solutions.This paper develops a facility location model for prepositioning supplies in preparation for disasters; the key feature of this formulation being the fact that it explicitly considers deprivation costs in the objective function. The model attempts to minimize the global social costs, as the sum of both private costs (i.e. costs of transportation, inventory costs and fixed costs of facilities) and deprivation costs, determining the amount per type of product to be prepositioned for serving the areas affected by a disaster during the initial response. The model focuses on those assistance interventions that should be carried out immediately, i.e. within the first 24 h of a humanitarian crisis. We applied the model, using real information, to the Colombian Caribbean region, which was affected by floods in 2010 and 2011. Results demonstrate that deprivation costs represent more than 50% of the total social cost.     

Measuring trustworthiness of information diffusion by risk discovery process in social networking services

Most of current social network services are vulnerable to malicious actions. For example, rumor (e.g., contaminated and distorted information) can be diffused along the social links. In this paper, given a social network service, we design a peer-to-peer (P2P) network, and propose a robust information diffusion model to efficiently detect the malicious peers from which a risk (i.e., rumor) has been generated on the P2P network. Thereby, by aggregating social interactions among users, a set of interaction sequences are obtained. Given a set of interaction sequences, statistical sequence mining method is exploited to discover a certain social position which provides peculiar patterns on the P2P networks. For evaluating the proposed method, we conducted two experimentations with NetLogo simulation platform for risk discovery on social network.     

The maximal covering location problem with accessibility indicators and mobile units

We study the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units that maximizes the facilities coverage, the accessibility of the zones to the open facilities, and the spatial disaggregation. The main characteristic of our problem is that mobile units can be deployed from open facilities to extend the coverage, accessibility, and opportunities for the inhabitants of the different demand zones. We formulate the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units as a mixed-integer linear programming model. To solve larger instances, we propose a matheuristic (combination of exact and heuristic methods) composed of an Estimation of Distribution Algorithm and a parameterized Maximal Covering Location Problem with Accessibility Indicators and Mobile Units integer model. To test our methodology, we consider the Maximal Covering Location Problem with Accessibility Indicators and Mobile Units model to cover the low-income zones with Severe Acute Respiratory Syndrome Coronavirus 2 patients. Using official databases, we made a set of instances where we considered the poverty index, number of population, locations of hospitals, and Severe Acute Respiratory Syndrome Coronavirus 2 patients. The experimental results show the efficiency of our methodologies. Compared to the case without mobile units, we drastically improve the coverage and accessibility for the inhabitants of the demand zones.     

Spatial market equilibria with flow-dependent supply and demand: The single commodity case

Existence and uniqueness of spatial price equilibria are analyzed for a single commodity market network in which supply and demand levels are allowed to depend on commodity flows as well as market prices. This framework makes possible the explicit incorporation of flow-dependent shipment costs into market supply and demand functions. Moreover, since many quantity signals are also expressible as flow-dependent variables, it is possible to incorporate a number of recent models of supply and demand behavior which allow for quantity signals as well as price signals. In this context, the main result of the paper is to establish the existence of spatial price equilibria for such market networks under quite general conditions. In addition, certain uniqueness results are established for the case of arc-generated networks.     

Infringing use as a path to legal consumption: Evidence from a field experiment

Digitization has transformed how users find and use copyrighted goods, but many existing legal options remain difficult to access, possibly leading to infringement. In a field experiment, we contact firms that are caught infringing on expensive digital images. E-mails to all firms include a link to the licensing page of the infringed image; for treated firms, we add links to a significantly cheaper licensing option. Making infringers aware of the cheaper option leads to a 14-fold increase in the ex-post licensing rate, albeit from an extremely low baseline for the control firms. Two additional experimental interventions, designed to reduce search costs for (i) price and (ii) product information, also have large positive effects. Our results suggest that ex-post monetization (e.g., licensing after use) may expand the market, and that rights holders can create value by minimizing search and transactions costs.     

Emergence of innovation networks from R&D cooperation with endogenous absorptive capacity

This paper extends the existing literature on strategic R&D alliances by presenting a model of innovation networks with endogenous absorptive capacity. The networks emerge as a result of dynamic cooperation between firms occupying different locations in the knowledge space. Partner selection is driven by absorptive capacity which is itself influenced by cognitive distance and R&D investment allocation. Under different knowledge regimes, we examine the structure of networks that emerge and how firms perform within such networks. We find networks that exhibit small world properties which are generally robust to changes in the knowledge regime. Certain network strategies such as occupying brokerage positions or maximising accessibility to potential partners pay off, especially in ‘young’ industries with limited involuntary but abundant voluntary spillovers. This particular result is driven by endogenous absorptive capacity.     

Aspects of complexity in citizen–bureaucrat corruption: an agent-based simulation model

In this paper, the complexity-based approach is used to analyse corruption and its internal economics and dynamics. To better understand the drivers of corruption, we employ an agent-based model with heterogeneous agents (bureaucrats and citizens), the interactions of which determine the level of corruption in a society. The emergence of a prevailing social norm of corruption is shown to be significantly influenced by the initial conditions (i.e., history and habits). A cost analysis demonstrates that a relatively limited financial investment is required for the phase transition from the corrupt to the non-corrupt state. The concept of opportunity costs is used to express the value of information shared within an agent’s social group that improves agent decision-making. Incomplete information and uncertainty in the legal system help to reduce corruption by promoting a fear of engaging in corruption in a society. The results of this research may offer useful insights for informing an effective anti-corruption policy.

     

A Huff model with firm heterogeneity and selection. Application to the Italian retail sector

ABSTRACT

In this paper, firm heterogeneity (in terms of productivity, i.e., marginal costs) is incorporated into a Huff model of competition in the Italian retail sector. A higher market potential in the trade area is associated with higher average productivity and lower productivity dispersion through selection of the best stores. The analysis, based on a unique data set encompassing 14,212 Italian retailers, finds support for this relationship in Southern Italy, but not in Northern and Central Italy (where opposite results are obtained in some cases), suggesting the selection dynamics are affected by context factors (other than provincial/regional accessibility) related to an upper geographical scale. The results are robust to controlling for local context factors such as financial risk and floor size restrictions. Floor size restrictions are found to enhance selection.     

Modelling international sovereign risk information spillovers: A multilayer network approach

Applying the TVP-VAR model, we creatively construct multilayer information spillover networks containing return spillover layer, volatility spillover layer and extreme risk spillover layer among 23 countries in the G20 to explore international sovereign risk spillovers. From the perspective of system-level and country-level measures, this article explores the topological structures of static and dynamic multilayer networks. We observe that (i) at the system-level, multilayer measures containing uniqueness edge ratio and average edge overlap show each layer has unique network structures and spillover evolution behavior, especially for dynamic networks. Average connectedness strength shows volatility and extreme risk spillover layers are more sensitive to extreme events. Meanwhile, three layers have highly intertwined and interrelated relations. Notably, their spillovers all show a great upsurge during the crisis (financial and European debt crisis) and the COVID-19 pandemic period. (ii) At the country-level, average overlapping net-strength shows that countries’ roles are different during distinct periods. Multiplex participation coefficient on out-strength indicates we’ll focus on countries with highly heterogeneous connectedness among three layers during the stable period since their underestimated spillovers soar in extreme events or crises. Multilayer networks supply comprehensive information that cannot obtain by single-layer.     

Risk-sharing networks and farsighted stability

Evidence suggests that in developing countries, agents rely on mutual insurance agreements to deal with income or expenditure shocks. This paper analyzes which risk-sharing networks can be sustained in the long run when individuals are farsighted, in the sense that they are able to forecast how other agents would react to their choice of insurance partners. In particular, we study whether the farsightedness of the agents leads to a reduction of the tension between stability and efficiency that arises when individuals are myopic. We find that for extreme values of the cost of establishing a mutual insurance agreement, myopic and farsighted agents form the same risk-sharing networks. For small costs, farsighted agents form efficient networks while myopic agents don’t.     

Campaign dynamics of cognitive accessibility of political judgments: measuring the impact of campaigns and campaign events using response latencies in two German rolling cross section studies

Do campaigns matter? Based on two rolling cross-section computer-assisted telephone surveys conducted in the run-up to the 2009 and 2013 German Federal Election, we test whether we can detect campaign effects on the accessibility of voters’ judgments: how do response latencies of political judgments evolve over the course of campaigns? The study uses response latencies, i.e. the standardized time it takes respondents to answer a survey question, as a proxy measurement of cognitive accessibility of political judgments. If campaigns do help voters to make up their minds, we should be able to observe changes at the implicit level of response latencies. Do people answer questions about their voting behavior and political attitudes faster as Election Day comes closer? Our results suggest that attitudes towards candidates and voting intentions become more cognitively accessible during campaigns whereas the accessibility of party identification is conditional on the contextual features of campaigns. In addition we find specific short-term effects of TV debates.     

Bilevel optimization for the reorganization of inland river ports: A niche perspective

To address the problems of duplicate construction, disorderly competition, small scale, and weak functionality, we examine the reorganization optimization of an inland river port group to realize its coordinated development. Considering port customers' decision-making behaviors, we propose a bilevel programming model for inland river port group reorganization based on niche theory. More specifically, an upper-level model is used to develop a reorganization plan, including the inland river port spatial layout and expansion extent, to maximize the value contributed by the port group to its region and industry and minimize the competition among the ports from the perspective of port management. More specifically, two upper-level objectives can be creatively measured by niche breadth and niche overlap. A lower-level model oriented to port customers aims to reduce their respective logistics costs by designing a transportation plan and providing feedback to the upper-level model to facilitate adjustments for port group reorganization. Since the dynamic interaction between the upper- and lower-level models significantly increases model complexity, we develop a hybrid heuristic algorithm by incorporating a genetic algorithm and an exact solution method. To verify the applicability of the proposed model and the efficiency of the developed hybrid approach, we conduct a series of numerical experiments on a real-world case study concerning Jining City, Shandong Province, China. Our case study also provides managerial insights into investment scale, land-use intensification, and the balance of planning objectives that may be useful for port managers.     

A strategic analysis of network reliability

Abstract. We consider a non-cooperative model of information networks where communication is costly and not fully reliable. We examine the nature of Nash networks and efficient networks. We find that if the society is large, and link formation costs are moderate, Nash networks as well as efficient networks will be ‘super-connected’ i.e. every link is redundant in the sense that the network remains connected even after the link is deleted. This contrasts with the properties of a deterministic model of information decay, where Nash networks typically involve unique paths between agents. We also find that if costs are very low or very high, or if links are highly reliable then there is virtually no conflict between efficiency and stability. However, for intermediate values of costs and link reliability, Nash networks may be underconnected relative to the social optimum.     

Knowledge networks and universities: Locational and organisational aspects of knowledge transfer interactions

The aim of this paper is to explore the inter-organisational knowledge networks that universities in the UK engage in through their knowledge transfer activities. In particular, it analyses the extent to which organisational and locational factors are associated with the nature of these networks. Based on a UK-wide survey of universities, it is shown that the nature and formation of inter-organisational knowledge networks is related principally to the organisational characteristics of network actors, and secondarily to their spatial location. The characteristics of a network actor, in this case a university, are likely to influence the type, diversity and location of other actors with which it networks. Nevertheless, spatial location is an important secondary factor influencing network formation, especially the geographic reach of a university's network. It is further found that the value generated by universities from their knowledge networks is associated with the type of organisations within which they interact as well as their spatial location. It is concluded that such networks impact both regional innovation capability and regional competitiveness. The results have implications for policymakers, especially in terms of the spatial scale at which the demand and supply for university knowledge can be best mediated.