Contributions in Merlin

We identify the effects of the Basel III macroprudential tool Counter-Cyclical Capital Buffer on mortgage lending. Using the first dataset on responses from multiple banks to each household, we find no evidence of explicit rationing. But as the CCyB applied only to mortgages, banks with higher mortgage specialization or lower capital cushions raise prices by an extra eight basis points. Bank level data then show that this allows them to slow their mortgage growth and rebuild capital cushions. While market-wide mortgage growth did not slow down significantly, the composition of mortgage suppliers thus moved to previously less exposed banks.

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We study the intra-horizon value at risk (iVaR) in a general jump diffusion setup and propose a new model of asset returns called displaced mixed-exponential model, which can arbitrarily closely approximate finite-activity jump-diffusions and completely monotone Levy processes. We derive analytical results for the iVaR and disentangle the risk contribution of jumps from diffusion. Estimating the iVaR for several popular jump models using on S&P 100 option data, we find that option-implied estimates are much more responsive to market changes relative to their historical counterparts. Moreover, disentangling jumps from diffusion, jump account for about 90 percent of iVaR on average.

Wireless Sensor Networks (WSN) are networks composed of constrained devices. One problem related to WSN is how to secure the communication between the nodes of such a network, as cryptographic algorithms are usually resource intensive. Therefore, in this thesis, ECCforContiki, a security solution for WSNs is presented. ECCforContiki uses elliptic curve cryptography (ECC) for key generation and key exchange, and various symmetric key techniques for encryption between the network nodes. It does not rely on a certificate authority to provide authenticity, but uses asymmetric pre-shared keys. The solution was implemented on a WSN running the aggregation protocol TinyIPFIX on the operating system Contiki. As shown by the performed evaluation, the presented solution successfully secures the communication between sensor nodes without a central certificate authority.

Refactoring is a well-established practice that aims at improving the internal structure of a software system without changing its external behavior. Existing literature provides evidence of how and why developers perform refactoring in practice. In this paper, we continue on this line of research by performing a large-scale empirical analysis of refactoring practices in 200 open source systems. Specifically, we analyze the change history of these systems at commit level to investigate: (i) whether developers perform refactoring operations and, if so, which are more diffused and (ii) when refactoring operations are applied, and (iii) which are the main developer-oriented factors leading to refactoring. Based on our results, future research can focus on enabling automatic support for less frequent refactorings and on recommending refactorings based on the developer's workload, project's maturity and developer's commitment to the project.

In 2002, Switzerland began to adopt free movement of workers with the European Union. We study the effects of the resulting immigration wave on resident workers. We focus on the level of national skill groups and propose an Instrumental Variable approach to address the endogeneity of immigration in this setting. Mostly relying on administrative data on the 2002–2011 period, we find that immigration of foreign workers reduced unemployment of residents and had limited adverse effects on their wages and employment. One reason is that younger residents changed to more demanding jobs as a response to the arrival of immigrants.

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The time-use (or activity) patterns individuals perform on a typical day – their individual lifestyles – fundamentally shape our society and the environment we live in. Not only are lifestyles evolving over time, driven by societal and technological change, they also significantly contribute to the achievement of Sustainable Development Goal 12 “responsible consumption and production”, namely through the resource use and emissions associated with goods and services consumed to perform activities. We created an interactive, browser-based tool to visualize and intuitively explore statistical time-use data. The visualization helps to gain an overview about the available data, identify and compare common time-use patterns and draw up hypotheses about the relationship between changes in lifestyles and their social and environmental consequences. We use the tool to compare time-use data from different regions, time periods as well as socio-economic and demographic backgrounds and estimate the associated energy consumption. From a time-use perspective, any technological change which triggers changes in time allocation can only be environmentally sustainable if the environmental impact of the total of the activities performed after the change is lower than before.

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Stakeholder participation is a key success factor of Requirements Engineering (RE). Typically, the techniques used for identifying and involving stakeholders in RE assume that stakeholders can be identified among the members of the organizations involved when a software system is ordered, developed or maintained—and that these stakeholders can be told or even mandated to contribute. However, these assumptions no longer hold for many of today’s software systems where significant stakeholders (in particular, end-users and people affected by a system) are outside organizational reach: They are neither known nor can they easily be identified in the involved organizations nor can they be told to participate in RE activities. We have developed the GARUSO approach to address this problem. It uses a strategy for identifying stakeholders outside organizational reach and a social media platform that applies gamification for motivating these stakeholders to participate in RE activities. In this article, we describe the GARUSO approach and report on its empirical evaluation. We found that the identification strategy attracted a crowd of stakeholders outside organizational reach to the GARUSO platform and motivated them to participate voluntarily in collaborative RE activities. From our findings, we derived a first set of design principles on how to involve stakeholders outside organizational reach in RE. Our work expands the body of knowledge on crowd RE regarding stakeholders outside organizational reach.