Characterization and Proteolytic Maturation of Head Proteins in a Giant Salmonella Virus

Giant phages are of interest for biocontrol of pathogenic bacteria, however, there is limited knowledge about their biology. We study the Salmonella phage SPN3US to better understand virion structure and function. SPN3US has a contractile tail and a large T=27 icosahedral capsid that contains its 240-kb genome. Previous analyses showed the SPN3US virion is highly unusual because it contains \u3e80 different proteins, a number that is highly unusual for a tailed phage. In addition, there is a mass (\u3e40 MDa) of proteins ( ejection proteins ) within the head that enter the Salmonella cell, possibly with roles in host takeover at the onset of infection. However, there is limited knowledge of the composition of the mature particle, the roles of individual proteins and how the SPN3US head and virion assemble. To address this gap in knowledge this research characterized both wild-type phage and a tailless mutant of SPN3US using high performance mass spectrometry to more accurately define the head proteome. These data confirm the high structural complexity of the SPN3US virion with it containing 92 different proteins. The head was found to contain 54 proteins, of which 9 were determined to have undergone proteolytic cleavage by a phage-encoded protease. All of these processed proteins were cleaved C-terminal to the sequence motif AXE, including the protease responsible for these cleavages. These data provide new insight into head maturation events during virion assembly and form a strong foundation for future studies on the roles of individual head proteins. Overall, these experiments illustrate that mass spectrometry is a powerful tool for defining the composition of highly complex viral particles, including the identification of post-translational modifications indicative of maturation events during viral assembly, and could be more broadly implemented in the field

Essays on FinTech

FinTech typically describes the application of novel technologies in the financial services sector. These technological innovations aim to compete with traditional financial technologies and improve user experience on a broad range of financial applications. Examples range from peer-to-peer investing services and new settlement procedures to the use of smartphones for mobile banking. Each chapter of this dissertation deals with one of these examples with the goal to draw conclusions for broader economic questions. In the first chapter, Crowdfunding and Demand Uncertainty, I analyze the potential of reward-based crowdfunding to elicit demand information and improve the screening of viable projects vis-à-vis traditional external financing. Crowdfunding allows entrepreneurs to sell claims on future products directly to consumers to finance their investments. At the same time, this peer-to-peer sale of claims generates demand information that benefits the screening process for viable projects. I provide a characterization of the profit-maximizing crowdfunding mechanism when an entrepreneur knows neither the number of consumers who positively value the product nor their reservation prices. Using mechanism design theory, I show that the entrepreneur can finance all viable projects by committing to prices that decrease as the number of pledgers increases. This pricing strategy grants ex-post information rents to consumers with high reservation prices. However, if these information rents are large, then the entrepreneur prefers fixed high prices that lead to underinvestment since consumers with low valuations never participate. The second chapter, Building Trust Takes Time: Limits to Arbitrage in Blockchain-Based Markets, is a joint project with Nikolaus Hautsch and Stefan Voigt. We analyze the potential implications of distributed ledger technologies, such as blockchain, for cross-market trading. Distributed ledgers replace trusted clearing counterparties and security depositories with time-consuming consensus protocols to record the transfer of ownership. We argue that this settlement latency exposes cross-market arbitrageurs to price risk and theoretically derive arbitrage bounds that increase with expected latency, latency uncertainty, volatility in the underlying asset, and arbitrageurs' risk aversion. We then use Bitcoin order book and network data to estimate arbitrage bounds of, on average, 121 basis points, which in fact explain 91% of the observed cross-market price differences in our sample period. Consistent with our theoretical framework, we also find that periods of high latency-implied price risk exhibit large price differences, while asset flows across exchanges chase arbitrage opportunities. Our main conclusion is that blockchain-based settlement introduces a non-trivial friction that impedes arbitrageurs' activity. The third chapter, Perceived Precautionary Savings Motives: Evidence from FinTech, is coauthored with Francesco D'Acunto, Thomas Rauter, and Michael Weber. We use data from a European FinTech banking app provider to study the consumption response to the introduction of a mobile overdraft facility. In addition, we use the banking app to elicit consumers' preferences, beliefs, and motives. We find that users increase their spending permanently, lower their savings rate, and reallocate spending from non-discretionary to discretionary goods. Interestingly, users with a lot of deposits relative to their income react more than others but do not tap into negative deposits. We demonstrate that these results are not fully consistent with conventional models of financial constraints, buffer stock models, or present-bias preferences. We hence label this channel perceived precautionary savings motives: users with a lot of liquidity behave as if they had strong precautionary savings motives even though no observables, including the elicited preferences and beliefs, suggest they should

Quantitative analysis of historical material as the basis for a new cooperation between history and sociology

Der Autor erklärt die partielle Gegnerschaft zwischen Soziologen und Historikern aus ihren unterschiedlichen Zielstellungen und Ansätzen. Zur Verdeutlichung werden der evolutionäre, der funktionalistische und der empirisch-soziologische Ansatz vorgestellt. Diese Ansätze werden, aus Sicht des Historikers und des Autors, dem historischen Quellenmaterial nur bedingt gerecht. Die Entwicklung von quantitativen Analysen für historisches Material durch die Historiker bietet für den Autor eine Möglichkeit einer fruchtbaren Zusammenarbeit zwischen beiden Wissenschaften. Vor allen Dingen kann das so aufbereitete historische Material Fehleinschätzungen der Soziologen korrigieren, die bei der Suche nach generalisierenden Momenten in der Geschichte dem wirklichen Verlauf nicht gerecht werden. (BG

The use of ISSP for comparative research

Im Mittelpunkt der methodologischen Erörterungen steht die Frage nach dem Umgang mit komplexen Datensätzen aus dem 'International Social Survey Program' (ISSP) im Rahmen der vergleichenden Sozialforschung. Insbesondere die Tatsache, dass die Anzahl der im ISSP kooperierenden Länder von ursprünglich vier auf nunmehr dreissig gestiegen ist, wirft neue methodologische Forschungsprobleme hinsichtlich der unterschiedlichen Art und Weise der Datenerhebung auf. Der Autor diskutiert die Frage, ob es sich hier tatsächlich um ein neues Problem oder nur um ein differentes Problemverständnis in den einzelnen Ländern handelt, und stellt Überlegungen an, inwiefern es sinnvoll ist, alle Datensätze eines bestimmten Jahres aus dem ISSP zu verwenden. Er geht ferner auf die sich wandelnde Rolle des Nationalstaats und die Konsequenzen für die ISSP-Daten ein und stellt die Bedeutung der Mesoebene in international vergleichenden Studien heraus. Die Hauptprobleme sind seiner Meinung nach nicht technischer, sondern theoretischer Natur. Als Fazit hält er fest, dass mehr spezifische Kenntnisse über die untersuchten Länder und Teamarbeit mit einheimischen Sozialforschern für ein adäquates Untersuchungsdesign und die Analyse in der vergleichenden Forschung benötigt werden. (ICI

The cross-cultural use of sample surveys: problems of comparability

Der vorliegende Beitrag (zuerst 1968 erschienen) diskutiert die folgenden methodologischen und theoretischen Probleme der 'cross-cultural research': Der Wandel bei der Identifikation von Problembereichen; Fragen der Bedeutung und der verbalen Kommunikation; die Äquivalenz von Indikatoren; der Befragte als Einheit in design und Analyse; der Gebrauch des Kulturkonzepts im interkulturellen Vergleich; politische und verwaltungstechnische Probleme und einige soziale Auswirkungen dieses Ansatzes auf die vergleichende Sozialforschung. (pmb)'This article (first published in 1968) deals with the following problems of cross-cultural research: change in the identification of problems of cross-cultural research: change in the identification of problem areas; question meaning and problems of verbal communication; equivalence of indicators; the respondent as a unit in design and analysis; the usage of 'culture' in cross-cultural surveys; administrative and diplomatic problems; and some social effects of comparative social research.' (author's abstract