Formal Modelling and Automated Trade-off Analysis of Enforcement Architectures for Cryptographic Access Control in the Cloud

To facilitate the adoption of cloud by organizations, Cryptographic Access Control (CAC) is the obvious solution to control data sharing among users while preventing partially trusted Cloud Service Providers (CSP) from accessing sensitive data. Indeed, several CAC schemes have been proposed in the literature. Despite their differences, available solutions are based on a common set of entities—e.g., a data storage service or a proxy mediating the access of users to encrypted data—that operate in different (security) domains—e.g., on-premise or the CSP. However, the majority of these CAC schemes assumes a fixed assignment of entities to domains; this has security and usability implications that are not made explicit and can make inappropriate the use of a CAC scheme in certain scenarios with specific trust assumptions and requirements. For instance, assuming that the proxy runs at the premises of the organization avoids the vendor lock-in effect but may give rise to other security concerns (e.g., malicious insiders attackers). To the best of our knowledge, no previous work considers how to select the best possible architecture (i.e., the assignment of entities to domains) to deploy a CAC scheme for the trust assumptions and requirements of a given scenario. In this article, we propose a methodology to assist administrators in exploring different architectures for the enforcement of CAC schemes in a given scenario. We do this by identifying the possible architectures underlying the CAC schemes available in the literature and formalizing them in simple set theory. This allows us to reduce the problem of selecting the most suitable architectures satisfying a heterogeneous set of trust assumptions and requirements arising from the considered scenario to a decidable Multi-objective Combinatorial Optimization Problem (MOCOP) for which state-of-the-art solvers can be invoked. Finally, we show how we use the capability of solving the MOCOP to build a prototype tool assisting administrators to preliminarily perform a “What-if” analysis to explore the trade-offs among the various architectures and then use available standards and tools (such as TOSCA and Cloudify) for automated deployment in multiple CSPs.

The Downside of Heterogeneity: How Established Relations Counteract Systemic Adaptivity in Tasks Assignments

We study the lock-in effect in a network of task assignments. Agents have a heterogeneous fitness for solving tasks and can redistribute unfinished tasks to other agents. They learn over time to whom to reassign tasks and preferably choose agents with higher fitness. A lock-in occurs if reassignments can no longer adapt. Agents overwhelmed with tasks then fail, leading to failure cascades. We find that the probability for lock-ins and systemic failures increase with the heterogeneity in fitness values. To study this dependence, we use the Shannon entropy of the network of task assignments. A detailed discussion links our findings to the problem of resilience and observations in social systems.

Study on the Evolution of the Source-Flow-Sink Pattern of China’s Chunyun Population Migration Network: Evidence from Tencent Big Data

We construct a comprehensive analysis framework of population flow in China. To do so, we take prefecture-level administrative regions as the basic research unit of population flow and use source-sink theory and flow space theory. Additionally, we reveal the dynamic differentiation of population flow patterns and the evolution of population source-flow-sink systems. We try to provide a theoretical basis for the formulation of population development policies and regional spatial governance. The results show the following: (1) The Hu Huanyong Line has a strong spatial lock-in effect on population flow. Additionally, provincial capital cities, headed by Hangzhou, Nanjing, and Hefei, have played an increasingly prominent role in population flow. (2) The developed eastern coastal areas have undertaken China’s main population outflow. The net population flow is spatially high in the middle of the region and low on the two sides, exhibiting an “inverted U-shaped” pattern. Furthermore, the borders of the central provinces form a continuous population inflow area. (3) The hierarchical characteristics of the population flow network are obvious. Strong connections occur between developed cities, and the effect of distance attenuation is weakened. The medium connection network is consistent with the traffic skeleton, and population flow exhibits a strong “bypass effect”. (4) The source and sink areas are divided into four regions similar to China’s three major economic belts. The 10 regions can be refined to identify the main population source and sink regions, and the 18 regions can basically reflect China’s level of urbanization. The network of the population flow source-flow-sink system exhibits notable nesting characteristics. As a result, it creates a situation in which the source areas on both sides of the east and the west are convective to the middle. The hierarchical differentiation of the source-flow sink system is related to the differences between the east and the west and between the north and the south, as well as local differences in China.

Complaint behaviour in multichannel retailing: a cross-stage approach

PurposeThis paper analyses how the purchase channel and customer complaint goals affect the sequential choice of post–purchase complaint channels when customers experience a service failure followed by a service recovery failure (double deviation).Design/methodology/approachAn online survey involving a scenario manipulation was conducted with 577 apparel shoppers. The study employs multi-group latent class analysis to estimate latent customer segments within both online and offline groups of shoppers and compare latent classes between the two groups.FindingsThe results show that the purchase channel has a lock-in effect on the complaint channel, which is stronger for offline buyers. Moreover, there is evidence of channel synergy effects in the case of having to complain twice: shoppers who complain in store in the first attempt turn to online channels in the second complaint attempt, and vice versa. Complaint goals shape the choice of complaint channels and define different shopper segments.Originality/valueThe present study is the first to adopt a cross-stage approach that analyses the dependencies between the purchase channel and the complaint channel used on two subsequent occasions: the first complaint after a service failure and the second following a service recovery failure.

Analysis of the Cause of Household Carbon Lock-In for Chinese Urban Households

Household energy conservation is an important contributor to achieve the carbon emission reduction target. However, the actual energy-saving effect of Chinese households is under expectation. One reason for this is because household energy consumption is locked in at a certain level, which has become an obstacle to household carbon emission reduction. In order to reduce this obstacle, this study explored the cause of household carbon lock-in based on grounded theory, targeting newly furnished households. A theoretical model was developed to reveal the formation mechanism of carbon lock-in effect in the purchasing process of household energy-using appliances. NVivo 12 software was used to analyze the decoration diaries of 616 sample households, and the results showed that (1) the direct antecedent of the household carbon lock-in effect was the lock-in of purchasing behavior, and the household carbon lock-in effect was mainly exhibited in the consumption path dependence (of energy-using appliances) and the solidification of energy structure; (2) the willingness to purchase household appliances was the direct antecedent of purchasing behavioral lock-in, and the cost had a moderating effect on the transformation from purchase willingness to behavioral lock-in; and (3) in the process of purchasing household appliances, reference groups, value perception, and ecological awareness can promote purchasing behavioral lock-in by affecting willingness of purchase. Suggestions to promote unlocking of household carbon were also proposed.

Fractal Characteristics of Discontinuous Growth of Digital Company: An Entrepreneurial Bricolage Perspective

Digital companies exhibit discontinuous growth in the process of shifting from their existing core business to a newer and less familiar business. This pattern of growth often ends in failure mainly because companies invest most of their resources in maintaining the value network of their existing core business, which ultimately results in a “lock-in” effect. The fractal theory assumes that there are similarities among fractals within companies. These similarities may reduce the threats posed by the value network lock-in effect and increase the chances of successful discontinuous growth. In this study, we applied fractal theory to consider the following questions: (1) in what aspects does the successful discontinuous growth of digital companies exhibit fractal characteristics? (2) What strategy does digital companies use to ensure these fractal characteristics? We adopted an exploratory single-case study method and chose ByteDance as the case company to analyze its successful shift from Toutiao (a media platform) to Douyin (a short-video sharing platform). Our results show that (1) a necessary condition for the successful discontinuous growth of digital companies is that similarities exist (e.g., in technology or customer base) between the existing core business and the new business and (2) entrepreneurial bricolage is a strategy used by digital companies to ensure the existence of fractal characteristics of similarities. We discuss the theoretical contributions and practical implications of this finding.

JavaSMT 3: Interacting with SMT Solvers in Java

Satisfiability Modulo Theories (SMT) is an enabling technology with many applications, especially in computer-aided verification. Due to advances in research and strong demand for solvers, there are many SMT solvers available. Since different implementations have different strengths, it is often desirable to be able to substitute one solver by another. Unfortunately, the solvers have vastly different APIs and it is not easy to switch to a different solver (lock-in effect). To tackle this problem, we developed JavaSMT, which is a solver-independent framework that unifies the API for using a set of SMT solvers. This paper describes version 3 of JavaSMT, which now supports eight SMT solvers and offers a simpler build and update process. Our feature comparisons and experiments show that different SMT solvers significantly differ in terms of feature support and performance characteristics. A unifying Java API for SMT solvers is important to make the SMT technology accessible for software developers. Similar APIs exist for other programming languages.

Stay or switch? Investigating lock-in effect in multi-channel apparel retailing

The emergence of new sales channels, the irruption of new technologies and changes in personal and professional lifestyles have transformed purchasing behaviors throughout the shopping process. Prior research has addressed the effect of these changes in each channel separately, neglecting the study of such effects in multi-channel environments. This research investigates the relation between channel preference and spillover effect—and more particularly, lock-in effect—in apparel multi-channel retailing, with data collected from a survey of 432 Spanish shoppers. The results of the study facilitate further understanding of spillover effect and help companies improve their omnichannel strategies.

The Energy Lock-In Effect of Solar Home Systems: A Case Study in Rural Nigeria

Ongoing reductions in the costs of solar PV and battery technologies have contributed to an increased use of home energy systems in Sub-Saharan African regions without grid access. However, such systems can normally support only low-power end uses, and there has been little research regarding the impact on households unable to transition to higher-wattage energy services in the continued absence of the grid. This paper examines the challenges facing rural energy transitions and whether households feel they are energy ‘locked in’. A mixed-methods approach using questionnaire-based household energy surveys of rural solar home system (SHS) users was used to collect qualitative and quantitative data. Thematic analysis and a mixture of descriptive and inferential statistical analyses were applied. The results showed that a significant number of households possessed appliances that could not be powered by their SHS and were willing to spend large sums to connect were a higher-capacity option available. This implied that a significant number of the households were locked into a low-energy future. Swarm electrification technology and energy efficient, DC-powered plug-and-play appliances were suggested as means to move the households to higher tiers of electricity access.

Bi-Directional Feedback to the Welfare State and Public Opinion

Policy feedback between public opinion and social policy is likely bi-directional. At least theory suggests. However, most research uses a uni-directional model. By conceiving the relationship as bi-directional it is possible to extend Pierson’s increasing returns theory to the neoliberal era, mostly after the 1980s, when welfare states of the rich democracies saw many forms of retrenchment. By testing a bi-directional theory using bi-directional models, this paper argues that public opinion likely updated in response to retrenchment and contributes to a new lock-in effect of institutionalized retrenchment paths. The models use ISSP data and a measure of the size of the welfare state based on SOCX spending data combined with a neoliberal indicator form the Fraser institute for the period 1990-2016 across the rich democracies for which data are available.