Washington University Medical Center
Washington University St. Louis: Open ScholarshipNot a member yet
26344 research outputs found
Sort by
Reputational Effects of Backchannel Communications: Gender and Fourth-Party Perceptions of Workplace Gossip
No full textGossip—defined here as unsanctioned conversations about an absent third-party—is ubiquitous in human life, universal across cultures and contexts, making up to two-thirds of all interpersonal communication. I empirically investigate the form and content of workplace gossip across contexts and explore the perceptions of gossip from a fourth-party perspective. This perspective recognizes that although gossip is a triadic construct involving a sender, receiver, and target, gossip spreads to fourth-parties within the broader organizational network. Prior and ongoing work suggests that with gossip spreads information about the gossipers themselves, leading to substantive reputational effects. This perspective takes a more global view of the effects of gossip in organizations by including downstream recipients in its analysis. Across four studies I collect evidence for the types of positive and negative, work-related and personal gossip employees engage in at disparate workplaces (Study 1), perform correlational analyses to test whether gossip characteristics such as work-relatedness and valence predict various perceptions of gossipers (Study 2), conduct vignette experiments to test the causal impact of gossip on person perception (Study 3) and a moderated mediation model of attitudinal and behavioral responses to gossip, influenced by gossiper gender (Study 4). I find that gossip is viewed unfavorably not only in terms of warmth and morality, but also in terms of assertiveness and competence. Mediation analyses suggest this results in both positive and negative gossip senders as being deemed untrustworthy and evaluators’ intentions to socially exclude them. I do not find support for gender backlash against women—i.e., my data do not suggest moderation of the effects of gossip by gossiper gender
Essays in Corporate Governance and Financial Intermediation
Get PDFAntitrust regulations in banking have historically targeted commercial banking activities. In the first chapter, I ask does the consolidation of investment banks have competitive effects? Using the geographically fragmented municipal bond underwriting market as a natural laboratory and employing a stacked difference-in-differences specification, I find that the underwriting spread increases by 4.8% of its sample mean following within-market consolidation. The effects double for larger M&As or in more concentrated markets and do not dissipate over time. These M&As do not generate efficiency gains that manifest as lower bond yields or substitution of other issuer-paid services. The findings remain robust when examining M&As less prone to endogeneity concerns and are absent in several placebo tests. Further, Census data suggest that such consolidation is followed by higher financing costs and reduced issuance. My findings offer a novel perspective on bank antitrust regulations, which are currently in the spotlight for revision and modernization. In the second chapter, coauthored with Radha Gopalan and ALminas Zaldokas, we investigate another question at the intersection of finance and antitrust: the consequences of interlocking directorates between competing firms. We document that a firm’s gross margin increases by 0.8 p.p. after forming a new direct board connection to a product market peer. Gross margin also rises by 0.4 p.p. after a connection is formed to a peer indirectly through a third intermediate firm. Further, using barcode-level data of 2.7 million products, we show that new board connections are related to higher consumer good prices, a greater tendency for market allocation, and slower new product introductions. The effects are stronger when the newly connected peers share corporate customers or have similar business descriptions and hold when controlling for other inter-firm relationships. In the third chapter, coauthored with Paul Gertler, Brett Green, and David Sraer, we study Pay-as-you-go (PAYGo) financing, a novel contract that has recently become a popular form of credit, especially in low- and middle-income countries (LMICs). PAYGo financing relies on lockout technology that enables the lender to remotely disable the flow benefits of collateral when the borrower misses payments. This paper quantifies the welfare implications of PAYGo financing. We develop a dynamic structural model of consumers and estimate the model using a multi-arm, large scale pricing experiment conducted by a fintech lender that offers PAYGo financing for smartphones. We find that the welfare gains from access to PAYGo financing are equivalent to a 3.4% increase in income while remaining highly profitable for the lender. The welfare gains are larger for low-risk consumers and consumers in the middle of the income distribution. Under reasonable assumptions, PAYGo financing outperforms traditional secured loans for all but the riskiest consumers. We explore contract design and identify variations of the PAYGo contract that further improve welfare
Single-molecule orientation and localization microscopy
No full textSingle-molecule localization microscopy (SMLM) offers enhanced spatial resolution in optical microscopy, providing detailed insights into the spatial organization of proteins in cells at the nanoscale. Over the past decade, SMLM has progressively incorporated the capability to retrieve the orientations of single molecules using their polarized dipolar emission pattern. Here we explore recent advancements in single-molecule orientation and localization microscopy (SMOLM), which yields super-resolved images of molecular three-dimensional (3D) orientations, wobble and 3D positions. This advancement opens possibilities to explore the nanoscale organization and conformation of biological molecules as well as to monitor and design local 3D optical fields in nanophotonics. We cover the principles of SMOLM, discuss recent advances and applications in biology and photonics, and finally highlight exciting future directions and challenges in the field
On Expertise Change: The Use and Misuse of Cultural Evolutionary Models
Get PDFExpertise is a major topic in the thoughts of Socrates, Plato, and Aristotle in the West, as well as in the thoughts of Daoist and Buddhist philosophers in the East. Expertise interests ancient philosophers due to the distinctive phenomenology of expertise, the puzzle surrounding the relationship between declarative knowledge and expertise, the practical process of expertise formation, and the use of expertise acquisition as a model for ethical and epistemic development. Philosophical interest in expertise has resurfaced in the last century, particularly regarding the phenomenology of expert performance, the relation between knowledge and expertise, and expertise-based models of ethical and epistemic virtues. What is missing from current philosophy is an account of expertise change. The ancients are concerned with how expertise changes within an individual’s lifetime. With the advent of Darwin’s evolutionary theory, the question of expertise change adds another dimension: how does expertise change within a human group over successive generations? My dissertation is about both types of expertise change. I define expertise as skills that take at least years of effective training for most people to develop. A proper account of expertise change needs to describe its pattern since the beginning of our species. Foragers in the late Pleistocene were already experts at crafting and hunting. Take hunting as an example. Modern foragers’ children follow older children to play hunting games using toy weapons; adolescents hunt with adults and copy hunting tricks from the mature hunters (for a recent review, see Lew-Levy et al. 2017). For certain types of prey, average hunting proficiency reaches its peak after decades of social learning. Richerson, Boyd, Henrich, and Heyes propose to explain change in expertise through cultural evolutionary theory (Boyd and Richerson 2005; Henrich 2015; Boyd 2018; Birch and Heyes 2021). They define culture as socially inherited information stored in the brain capable of explaining behavior. Expertise is a subcategory of culture that no individual can invent alone, or what I call NICIA culture (Richerson and Boyd 2005; Henrich 2015; Boyd 2018). NICIA culture is produced through the historical accumulation of cultural innovations, which I call historical cultural change. The possibility of historical cultural change is supported by population models analogous to those in population genetics. Godfrey-Smith (2009, chapter 8) describes population models as a broader category that subsumes selectionist models as a subset. In population models, individuals within the population are of a similar type, sharing many common properties. Formal analysis or simulation, when applied to population models, can help derive population-level dynamics from the aggregated effect of one-on-one interactions at the individual level. I follow Lewens (2015) by referring to Richerson, Boyd, and Henrich’s population models as kinetic models. My dissertation aims to criticize the use of kinetic models to explain historical cultural change. I think that the primary utility for explaining historical cultural change is to explain expertise change, but if we look closer at how individuals develop expertise, kinetic explanations of expertise change lose their attraction. In chapter 2, I argue that the primary utility for positing historical cultural change is to explain expertise change. Cultural evolutionary theorists posit historical cultural change to explain the emergence and maintenance of NICIA culture. However, NICIA culture is defined in a negative way, which renders it notoriously difficult to operationalize. A more useful conceptual framework needs a positive description of the kind of culture that requires historical explanation. I argue that the positive description of developmental complexity, i.e., the required time for learning, can partially replace the role of NICIA culture in specifying the scope of cultural evolutionary models. Since expertise is a developmentally complex skill, the main point of explaining historical cultural change is to enhance our understanding of expertise change. If a cultural evolutionary model fails to explain expertise change, then the model loses significant motivation. The phenomena subsumed under the category of expertise are still too heterogeneous. In Chapter 3, I argue that expertise can be roughly classified in a three-dimensional space according to three types of training required to acquire it: the demands of virtuosic training, the demands of improvisational training, and the demands of physical training. Effective virtuosic training depends on deliberate practice (Ericsson et al. 1993). Effective physical training depends on repeating the same training activity at appropriate temporal intervals. Sustenance expertise of late Pleistocene foragers, as well as moral expertise, scientific expertise, chess, and psychotherapy, are expertise domains that are high in improvisational demands, but not necessarily high in virtuosic and physical demands. I argue that expertise in these domains is mostly gained through effective improvisational training, which crucially depends on the variation in training experience. I argue that neither selectionist models nor the more liberal kinetic models are useful in explaining change in improvisational expertise. I discuss problems with selectionist models of expertise change in Chapter 4 and problems with kinetic models in Chapter 5. What causes problems for both types is the vague teacher-student lineages of improvisational expertise. One cannot attribute the development of improvisational expertise solely to the teaching of one master; the result of training must always be attributed to the entire guild, including its environment. In the latter half of Chapter 5, I delimit the proper scope for cultural selectionist models in explaining expertise change. I think they are useful at least when (1) the focal traits are much simpler than expertise but still relevant for expertise acquisition, and (2) the aspect of expertise change being explained is limited to the maintenance and stabilization of expertise acquisition. I situate this aspect within a more fine-grained description of the historical patterns of expertise change. The last chapter, chapter 6, critically examines the popular description of cultural change at the population level as being faster than biological change. Richerson and Boyd use this seemingly obvious statement to explain why sustenance expertise remains a cultural trait instead of being genetically assimilated. I analyze the kind of evolutionary speed comparison between cultural and biological change that is required to support this built-for-speed explanation of the stable cultural status of expertise, and I reject such speed comparisons as inoperationalizable. It may seem that some cultural traits transform faster than some morphological traits, but very little can be inferred from such cross-trait speed comparisons
The Effects of Electoral Outcomes and Cross-party Relationships on Affective Polarization
Get PDFThis dissertation explores several under-studied aspects of affective polarization through four chapters. The first chapter discusses the history of polarization research and the measurement challenges facing polarization scholars. The second chapter analyzes how electoral outcomes differentially influence Democrats\u27 and Republicans\u27 inparty, outparty, and general affect. I find that winning elections affects both outparty and inparty attitudes, but the size and direction of these effects varies by party: electoral success reduces Republicans\u27 inparty affect, but for Democrats success reduces outparty affect. The third and fourth chapters contain survey experiment data measuring the effects of cross-partisan relationships. I find that positive relationships with typical outparty supporters result in more positive assessments of the outparty. I put forth a theory of chosen versus circumstantial relationships, contending that choosing to include a cross-party contact in one\u27s life affects attitudes differently than cross-party contacts that are within one\u27s social circle by chance or life circumstances. I find support for this theory, with chosen relationships relating to lower partisan animosity and greater propensity to form new cross-party relationships. Taken together, this dissertation reveals that affective polarization is a nuanced and complicated phenomenon. I find considerable evidence that affective polarization remains high in today\u27s society. However, these results demonstrate that negative attitudes are positively influenced by cross-party contact, and are not extremely exacerbated by electoral outcomes. This dissertation provides a cautiously optimistic outlook on the state of affective polarization in contemporary American society
Staging Suffering: Depictions of the Family Space in German Naturalist Drama
No full textThis dissertation engages with depictions of middle class families in six Naturalist dramas: August Strindberg’s Der Vater (Fadren) (1887), Gerhart Hauptmann’s Das Friedensfest (1890) and Einsame Menschen (1891), Arno Holz and Johannes Schlaf’s Die Familie Selicke (1890), Elsa Bernstein’s (pseudonym Ernst Rosmer) Wir Drei (1893), and Hermann Sudermann’s Heimat (1893), by examining how conflicts are realized within the family space and the impact of the family space on familial suffering. The family space may be understood as a collective, relational arrangement of figures, objects, and perceptions—components of space as theorized by sociologist Martina Löw—that creates a representation of the family in these six dramatic works. In addition to Löw’s conception of space, this project considers elements of dramatic space that are important to these texts as performative works. The introduction provides an overview of the German family, Löw’s theory, the spatial turn more broadly, and the approaches taken by the dissertation. The first chapter centers on Einsame Menschen and Wir Drei, two works that depict familial conflict where figures alter their emotional and physical proximity to one another in order to deal with marital discord brought on by the presence of an additional female figure. The second chapter engages with Die Familie Selicke and Der Vater, two plays focused on families whose main conflict(s) are focused on the uncertainty of the future and individuals’ struggles to assert their familial identities. In both dramas, the family space emphasizes impressions of entrapment and the futility of fantasizing about the future with no means of escaping present circumstances, and the family space is reconfigured through figures’ abilities to uphold or upend their familial roles. The final chapter focuses on Das Friedensfest and Heimat, two plays that center on familial conflicts rooted in the past, and it explores how figures are brought back into the family space in order to reconcile with one another but are ultimately unsuccessful in doing so. Both of these dramas engage with whether the past can be overcome as figures reenter the space of the family home, and the space is ultimately a reflection of the past’s impact on the present. Taken together, these six dramas present the family space and its reconfigurations as a means of highlighting familial tensions and conflicts in the texts and on the stage, as familial suffering among the middle classes in the last decades of the nineteenth century is particularly showcased through the family space
Spectral Mixture Analyses of Hematite-Rich and Clay-Bearing Terrains in Meridiani and Oxia Planum, Mars
No full textMinerals have characteristic absorption features in the visible and near-infrared wavelength range, which can be detected in remotely sensed observations using methods such as spectral parameter maps or modeled via spectral mixtures. My dissertation uses both methods on orbital and ground-based single-scattering albedo data to assess the surface compositions of Meridiani Planum and Oxia Planum, regions of Mars that are rich in secondary minerals. A probabilistic approach to spectral unmixing was adopted to account for the nonuniqueness of model solutions, with endmember abundance and grain size maps being produced for Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) orbital images. For the Oxia Planum study, the probabilistic algorithm was modified to accommodate a sparse unmixing technique, in order to determine the optimal combination of endmembers on a per-pixel basis. The unmixing results for Meridiani Planum CRISM data, together with Panoramic Camera-based spectral mixing models from the Mars Exploration Rover Opportunity, suggest that modern winds are enhancing ferric absorption signatures in this area by removing dust from surfaces. In Oxia Planum, spectral parameter maps are consistent with detections of clay-bearing materials in previous works. Model results from the sparse probabilistic unmixing corroborate the clay detections and show that carbonates may also associate with the clays in some terrains, offering more insight into the formation history of the region. This research demonstrates the continued usefulness of spectral mixture analysis for compositional studies, helping us to better understand the geology of Mars and to aid future exploration of its surface
Brahminical Infrastructures: States, Roads, and Lands in Dolpo, Nepal
No full textStudies focusing on infrastructures have predominantly examined the presence of the state (Carse, 2014; Harvey and Knox, 2015; Von Schnitzler, 2017). However, this top-down approach to analyzing infrastructural development has obscured the ways in which individuals value land and how that relationship evolves. While anti-colonial studies emphasize the significance of land-based resistance for colonized peoples, these studies are somewhat marginalized within the anthropology of infrastructure (Fanon 1961; Coulthard 2014; Estes 2019). The road construction project, which fortifies infrastructural links between Nepal and China, traverses Indigenous Dolpo territories and is predominantly managed by government and non-government officials from high-caste groups who espouse ideas of progress that engender inequalities in Dolpo. In collaboration with the Dolpo community, the project explores the following questions: How does infrastructure sustain a Brahmanical capitalist state? How do local populations respond to and resist the caste-based regimes of land ownership? Drawing theoretical insights from the studies on enduring colonial impacts on Indigenous communities, anthropology of infrastructure, political ecology, and caste studies, it examines: (1) how state-led infrastructure development sustains settler colonialism; (2) how values and practices around Indigenous lands change because of state infrastructures; and (3) how state infrastructures shape Indigenous land collectives. Based on eighteen months of ethnographic fieldwork in Nepal, my principal assertions are: Road construction sustains the Brahmanical capitalist state and its political order on Indigenous lands. Indigenous peoples actively reaffirm their own processes of world-making to oppose the prevailing political order that negates Indigenous sovereignty. Ethnography involving interviews, participant observation, case studies, and surveys of the community and its various organizations centers on indigenous knowledge, perspectives, and experiences. This research aims to foreground the analysis of the evolving meanings, valuations, and relations to the land, providing an in-depth understanding of the local disparities precipitated by the ongoing road construction and its impact on land tenure and valuation. The goal is not to reduce every process to the land, but rather to use land valuation – both economic and semiotic – as a means to understand how indigenous meanings, practices, and strategies of land usage are linked to a broader universe of historical and material conditions in which Dolpo developed and continues to do so. This study is committed to documenting the understanding and expression of Dolpo\u27s struggles for survivance, dignity, and rights in response to historically ingrained caste, class, and ethnic discrimination. This research will contribute to the scant understanding of how different social groups experience the landlord state and enact new meanings and practices in an attempt to keep state appropriation at a distance
Mechanisms of ssDNA Gap Resection in BRCA1-proficient and -deficient Cells
Get PDFSingle-stranded (ss) DNA gaps are potentially genome-destabilizing structures that require prompt repair (or filling) to prevent DNA breakage and genome instability. We previously showed that gap repair is defective in cancer cells with deficiencies in the breast cancer susceptibility gene BRCA1. These findings explain why ssDNA gaps accumulate in BRCA1-deficient cells in response to therapies that target DNA, such as platinum-based compounds, or therapies that inhibit specific repair pathways, such as PARP inhibitors (PARPi). We also discovered that gap repair can be restored in BRCA1-deficient cells by inhibiting MRE11 nuclease activity, indicating that nuclease processing plays a central role in ssDNA gap metabolism. While processing of DNA double-stranded breaks has been widely studied, the corresponding molecular details are missing for ssDNA gaps. This thesis begins by first elucidating the molecular mechanism that regulates ssDNA gap processing in BRCA1-proficient and -deficient cells by combining electron microscopy and single-molecule DNA fiber approaches with in vitro biochemical assays. We discovered that MRE11 resects the 3’ end of the ssDNA gaps, whereas the long-range resection nucleases EXO1 and DNA2 process the 5’ end. We also discovered that DNA2 works in concert with either BLM or WRN and that both the EXO1 and the DNA2/BLM or DNA2/WRN resection pathways are utilized to resect the 5’ end of the gap. Importantly, we also found that this nuclease resection pathway is deregulated in BRCA1-deficient cells, leading to larger ssDNA gaps compared to BRCA1-proficient cells. These larger ssDNA gaps cannot be efficiently repaired by the canonical gap repair pathways and are converted into double-stranded breaks, leading to genomic instability. Our studies provide the first complete model for ssDNA gap resection following treatment with PARPi or DNA-damaging agents. This is critical to explain why ssDNA gaps cannot be repaired in BRCA1-deficient cells and to better understand the molecular mechanisms that modulate PARPi response in BRCA1-deficient tumors. Lastly, we investigated whether factors involved the ssDNA gap resection pathway are mutated in BRCA1-deficient cancers. In collaboration with Dr. Cynthia Ma, we combed through approximately 50 BRCA-mutated patient’s data who were treated with PARPi, providing the framework for future analysis
The Given, The Loved, and The Found: A Series of Communications Regarding My Ever-Changing Book Collection
Get PDFUndergraduate winner: 2nd place, 2025, 38th Annual Carl Neureuther Student Book Collection Competitio