Essays on Market Design

“Market Design […] strives to understand how the design of marketplaces influences the functioning of markets” (Roth 2018, p. 1609). The simple but powerful rationale of market design is to improve markets by actively designing them, guided by economic theory, empirical data, and carefully designed economic experiments. In recent years, economists have been successful in designing a variety of institutions, including spectrum auctions, electricity markets, feedback systems, kidney exchanges, and school choice (Chen et al., 2020). This thesis consists of four chapters, all devoted to different aspects and areas of market design. Another unifying element of this thesis is the methodology. In all chapters, laboratory experiments are conducted, data are analyzed, and the results are linked to real-world applications. Laboratory experimental studies are a particularly useful tool in the context of market design. They are often compared to a wind tunnel, where the performance of existing designs is studied in a simplified environment or even new design ideas are tested in a controlled environment (Chen et al., 2020). The first chapter looks at auction design. We investigate the puzzle behind the popularity of a non-binding soft reserve price in practice. Here, we use the laboratory as a "wind tunnel" to compare the performance of different existing auction designs in a controlled environment. Chapter two focuses on the design of feedback systems. In this chapter, we propose a small but very effective modification to existing feedback withdrawal mechanisms. Therefore, we use the possibility of laboratory experiments to test a new design idea that has not yet been implemented in practice and for which, of course, no field data are available. The third chapter is concerned with the area of school choice. Here, I investigate the value of fairness to participants in school choice markets, which can guide a market designer in choosing an appropriate algorithm. A laboratory experiment allows for the observation and control of student preferences that are typically unobservable in field data. Finally, chapter four focuses on norm information acquisition. When designing real-world institutions, incentives must be aligned with behavior in terms of underlying goals (Bolton and Ockenfels 2012). Therefore, social norms, which are known to be a powerful force influencing behavior, are of great importance for market design. We study how economic agents choose between different types of norm information in a social choice context with uncertainty

Fixing feedback revision rules in online markets

Feedback withdrawal mechanisms in online markets aim to facilitate the resolution of conflicts during transactions. Yet, frequently used online feedback withdrawal rules are flawed and may backfire by inviting strategic transaction and feedback behavior. Our laboratory experiment shows how a small change in the design of feedback withdrawal rules, allowing unilateral rather than mutual withdrawal, can both reduce incentives for strategic gaming and improve coordination of expectations. This leads to less trading risk, more cooperation, and higher market efficiency.Series: Department of Strategy and Innovation Working Paper Serie

Beitrag zur Multiskalensimulation kurzfaserverstärkter Kunststoffe

Die vorliegende Arbeit befasst sich mit der Modellierung kurzfaserverstärkter Kunststoffe und der draus folgenden Berechnung effektiver Compositeeigenschaften. Die grundlegen-de Idee für alle Untersuchungen in dieser Arbeit ist, dass eine gesteigerte Information auf Mikrostrukturebene zu einer besseren Vorhersage der effektiven Compositeeigenschaften führt. Welche Informationen und wie sie genutzt und verarbeitet werden, wird in dieser Arbeit eingehend analysiert und bewertet. Insbesondere steht dabei die Information über die Faserorientierung im Vordergrund der durchgeführten Untersuchungen. Darüber hinaus werden weitere Informationen über die Mikrostruktur hinsichtlich ihrer Auswirkungen auf die effektiven Compositeeigenschaften untersucht. Hierzu werden zahlreiche mögliche Mikrostrukturen als Repräsentative Volumen Elemente mit veränderlichen Modellierungsparametern mit der Finite-Elemente Methode analysiert. Weiter wird in dieser Arbeit ein neuronales Netz auf Basis einer Datengrundlage von RVEs erarbeitet und vorgestellt. Hierzu werden RVEs mit zufällig gewählten Inputparametern erstellt und ausgewertet. Die RVEs unterscheiden sich dabei durch ihre Faserorientierung, Faser-länge, Faservolumenanteil und durch die verwendeten Eigenschaften der Matrix. Es wird eindeutig gezeigt, dass das neuronale Netz im Mittel die Ergebnisse der RVEs besser approximieren kann als eine zweistufige Homogenisierung auf Basis der Methode von Mori-Tanaka. Der Zielkonflikt zwischen genauerer Modellierung und schnellerer Berechnungen auf der Bauteilebene kann mit dem vorgestellten Vorgehen deutlich entschärft werden

Multi-heme Cytochromes in Shewanella oneidensis MR-1:Structures, functions and opportunities

Multi-heme cytochromes are employed by a range of microorganisms to transport electrons over distances of up to tens of nanometers. Perhaps the most spectacular utilization of these proteins is in the reduction of extracellular solid substrates, including electrodes and insoluble mineral oxides of Fe(III) and Mn(III/IV), by species of Shewanella and Geobacter. However, multi-heme cytochromes are found in numerous and phylogenetically diverse prokaryotes where they participate in electron transfer and redox catalysis that contributes to biogeochemical cycling of N, S and Fe on the global scale. These properties of multi-heme cytochromes have attracted much interest and contributed to advances in bioenergy applications and bioremediation of contaminated soils. Looking forward there are opportunities to engage multi-heme cytochromes for biological photovoltaic cells, microbial electrosynthesis and developing bespoke molecular devices. As a consequence it is timely to review our present understanding of these proteins and we do this here with a focus on the multitude of functionally diverse multi-heme cytochromes in Shewanella oneidensis MR-1. We draw on findings from experimental and computational approaches which ideally complement each other in the study of these systems: computational methods can interpret experimentally determined properties in terms of molecular structure to cast light on the relation between structure and function. We show how this synergy has contributed to our understanding of multi-heme cytochromes and can be expected to continue to do so for greater insight into natural processes and their informed exploitation in biotechnologies

Finite temperature quantum simulation of stabilizer Hamiltonians

We present a scheme for robust finite temperature quantum simulation of stabilizer Hamiltonians. The scheme is designed for realization in a physical system consisting of a finite set of neutral atoms trapped in an addressable optical lattice that are controllable via 1- and 2-body operations together with dissipative 1-body operations such as optical pumping. We show that these minimal physical constraints suffice for design of a quantum simulation scheme for any stabilizer Hamiltonian at either finite or zero temperature. We demonstrate the approach with application to the abelian and non-abelian toric codes.Comment: 13 pages, 2 figure

Investigation of hospital discharge cases and SARS-CoV-2 introduction into Lothian care homes

Background The first epidemic wave of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in Scotland resulted in high case numbers and mortality in care homes. In Lothian, over one-third of care homes reported an outbreak, while there was limited testing of hospital patients discharged to care homes. Aim To investigate patients discharged from hospitals as a source of SARS-CoV-2 introduction into care homes during the first epidemic wave. Methods A clinical review was performed for all patients discharges from hospitals to care homes from 1st March 2020 to 31st May 2020. Episodes were ruled out based on coronavirus disease 2019 (COVID-19) test history, clinical assessment at discharge, whole-genome sequencing (WGS) data and an infectious period of 14 days. Clinical samples were processed for WGS, and consensus genomes generated were used for analysis using Cluster Investigation and Virus Epidemiological Tool software. Patient timelines were obtained using electronic hospital records. Findings In total, 787 patients discharged from hospitals to care homes were identified. Of these, 776 (99%) were ruled out for subsequent introduction of SARS-CoV-2 into care homes. However, for 10 episodes, the results were inconclusive as there was low genomic diversity in consensus genomes or no sequencing data were available. Only one discharge episode had a genomic, time and location link to positive cases during hospital admission, leading to 10 positive cases in their care home. Conclusion The majority of patients discharged from hospitals were ruled out for introduction of SARS-CoV-2 into care homes, highlighting the importance of screening all new admissions when faced with a novel emerging virus and no available vaccine

SARS-CoV-2 Omicron is an immune escape variant with an altered cell entry pathway

Vaccines based on the spike protein of SARS-CoV-2 are a cornerstone of the public health response to COVID-19. The emergence of hypermutated, increasingly transmissible variants of concern (VOCs) threaten this strategy. Omicron (B.1.1.529), the fifth VOC to be described, harbours multiple amino acid mutations in spike, half of which lie within the receptor-binding domain. Here we demonstrate substantial evasion of neutralization by Omicron BA.1 and BA.2 variants in vitro using sera from individuals vaccinated with ChAdOx1, BNT162b2 and mRNA-1273. These data were mirrored by a substantial reduction in real-world vaccine effectiveness that was partially restored by booster vaccination. The Omicron variants BA.1 and BA.2 did not induce cell syncytia in vitro and favoured a TMPRSS2-independent endosomal entry pathway, these phenotypes mapping to distinct regions of the spike protein. Impaired cell fusion was determined by the receptor-binding domain, while endosomal entry mapped to the S2 domain. Such marked changes in antigenicity and replicative biology may underlie the rapid global spread and altered pathogenicity of the Omicron variant