Contributions in Merlin

Data often contains sensitive information, which poses a major obstacle to publishing it. Some suggest to obfuscate the data or only releasing some data statistics. These approaches have, however, been shown to provide insufficient safeguards against de-anonymisation. Recently, differential privacy (DP), an approach that injects noise into the query answers to provide statistical privacy guarantees, has emerged as a solution to release sensitive data. This study investigates how to continuously release privacy-preserving histograms (or distributions) from online streams of sensitive data by combining DP and semantic web technologies. We focus on distributions, as they are the basis for many analytic applications. Specifically, we propose SihlQL, a query language that processes RDF streams in a privacy-preserving fashion. SihlQL builds on top of SPARQL and the w-event DP framework. We show how some peculiarities of w-event privacy constrain the expressiveness of SihlQL queries. Addressing these constraints, we propose an extension of w-event privacy that provides answers to a larger class of queries while preserving their privacy. To evaluate SihlQL, we implemented a prototype engine that compiles queries to Apache Flink topologies and studied its privacy properties using real-world data from an IPTV provider and an online e-commerce web site.

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The US dollar and also increasingly the euro and in some instances the Swiss franc exhibit risk-minimizing capabilities in a wide range of international portfolios. From 1975 until the end of 2019, these currencies moved against both equity markets as well as additional asset classes such as bonds, real estate and commodities. This presents the possibility of holding specific amounts of currencies in an attempt to reduce risk in international portfolios. Given the expected return structure of an initial investment, a risk-minimizing investor can include such positions in a portfolio in order to reduce overall volatility. The financing of these long positions can be established by short selling other foreign exchange positions that are positively correlated with an investor’s initial investment. This is especially the case for the Australian and Canadian dollars as well as most emerging market currencies when investing in equities and beyond. Optimal hedging demands largely depend on investor sentiment, return expectations and preferred risk exposure. Defining these metrics alongside preferred asset classes can lead to substantial risk reduction, primarily in more aggressive portfolios. In the empirical part of the work, we show that di↵erent asset classes exhibit similar hedging demands but deviate substantially in the amount of currency held. This leads to a real estate or commodities investor holding a considerably larger amount of US dollars compared to an equity or bond investor. Moreover, we demonstrate that currency demands also tend to change over time, leading to sizeably distinct optimal allocations for di↵erent time periods.

The present article provides an efficient and accurate hybrid method to price American standard options in certain jump-diffusion models as well as American barrier-type options under the Black & Scholes framework. Our method generalizes the quadratic approximation scheme of Barone-Adesi & Whaley (1987) and several of its extensions. Using perturbative arguments, we decompose the early exercise pricing problem into sub-problems of different orders and solve these sub-problems successively. The obtained solutions are combined to recover approximations to the original pricing problem of multiple orders, with the 0-th order version matching the general Barone-Adesi & Whaley ansatz. We test the accuracy and efficiency of the approximations via numerical simulations. The results show a clear dominance of higher order approximations over their respective 0-th order version and reveal that significantly more pricing accuracy can be obtained by relying on approximations of the first few orders. Additionally, they suggest that increasing the order of any approximation by one generally refines the pricing precision, however that this happens at the expense of greater computational costs.

In this paper, we review the burgeoning but dispersed literature on chief executive officer (CEO) advice seeking, which has important effects on strategic decision making, the CEO’s and the board of directors’ effectiveness, and firms’ entrepreneurial orientation, innovativeness, and financial performance. We synthesize research findings about the key features of CEO advice seeking and its antecedents and outcomes across multiple levels of analysis. On the basis of our review, we identify important research gaps and develop a future research agenda that outlines new research questions and empirical foci that extend the current scope of analysis. We also highlight promising new theories and underutilized methods suitable for this area of research. With an integrative review and research agenda, we hope to stimulate cross-fertilization of different lines of inquiry and encourage new research that shines a spotlight on the remaining puzzles of CEO advice-seeking research.

Adolescence is a developmental period of increased sensitivity to social emotional cues, but it is less known whether young adults demonstrate similar social emotional sensitivity. The current study tested variation in reaction times to emotional face cues during different phases of emotional development. Ex-Gaussian parameters mu, sigma, and tau were computed, in addition to mean, median and standard deviation (SD) in reaction times (RT) during an emotional go/nogo-paradigm with fearful, happy, and calm facial expressions in 377 participants, 6-30 years of age. Across development, mean RT showed slowing to fearful facial expressions relative to both calm and happy facial cues, but mu revealed that this pattern was specific to adolescence. In young adulthood, increased variability to fearful expressions relative to both happy and calm ones was captured by SD and tau. The findings that adolescents had longer response latencies to fearful faces, whereas young adults demonstrated greater response variability to fearful faces, together reflect how social emotional processing continues to evolve from adolescence into early adulthood. The findings suggest that young adulthood is also a vulnerable period for processing social emotional cues that ultimately may be important to better understand why different psychopathologies emerge in early adulthood.

We investigate the compensation of counterparty exposure in the prices of structured products. Our analysis reveals that product issuers do not compensate retail investors for counterparty exposure before the Lehman default. Post-Lehman, retail prices no longer neglect this risk. We also measure retail investor attention towards issuer credit risk. For a given level of issuer credit risk, counterparty exposure is compensated more when attention is higher. Furthermore, issuers tend to construct products with larger counterparty exposure. Overall, our results shed light on the conditions under which financial engineering generates neglected risk.

Blockchain comes with the promise of being a disruptive technology with the potential for novel ways of interaction in a wide range of applications. Following broader application, scholarly interest in the technology is growing, though an extensive analysis of blockchain applications from a governance perspective is lacking to date. This research pays special attention to the governance of blockchain systems and illustrates decision problems in 14 blockchain systems from four application domains. Based on academic literature, semi-structured interviews with representatives from those organizations, and content analysis of grey literature, common problems in blockchain governance have been singled out and contextualized. Studying their enactment revealed their relevance to major organizational theories in what we labelled “Patrolling the borders,” “External Legitimation,” “Reduction of Discretionality,” and “Temporal Management.” The identification of these problems enriches the scarce body of knowledge on the governance of blockchain systems, resulting in a better understanding of how blockchain governance links to existing concepts and how it is enacted in practice.

STUDY OBJECTIVES: Stress can adversely impact sleep health by eliciting arousal increase and a cascade of endocrine reactions that may impair sleep. To date, little is known regarding continuous effects of real-world stress on physiological sleep characteristics and potential effects on stress-related psychopathology. We examined effects of stress on heart-rate (HR) during sleep and total sleep time (TST) during prolonged real-world stress exposure in medical interns. Moreover, we investigated the influence of previous stress and childhood trauma exposure on HR during sleep, TST, and its interaction in predicting anxiety. METHODS: We examined a sample of 50 medical students prior to and during their first internship, a well described real-world stressor. Heartrate and total sleep time were continuously collected over 12 weeks non-invasively by a wrist-worn activity monitor. Prior to starting the internship, at baseline, participants reported on their sleep, anxiety and childhood trauma exposure. They also tracked stress exposure during internship and reported on their anxiety symptoms after 3 months after this professional stress. RESULTS: Mean HR during sleep increased over time, while TST remained unchanged. This effect was more pronounced in interns exposed to childhood trauma exposure. In multilevel models, childhood trauma exposure also moderated the relation between individual HR increase and development of anxiety. CONCLUSIONS: Prolonged stress may lead to increased HR during sleep, whereas individuals with childhood trauma exposure are more vulnerable. childhood trauma exposure also moderated the relation between individual HR increase and development of anxiety. These findings may inform prevention and intervention measures.