Essays on the interaction between users and information systems

The role of information systems has evolved from providing decision support into enabling the majority of our daily operations, and the way users interact with information systems has changed dramatically as a result. The goal of this dissertation is to study phenomena that stem from the close interaction between users and information systems using empirical methodologies. The first essay of this dissertation focuses on the issue of sentiment manipulation. We show that strategic players might be incentivized to manufacture content on social media platforms and opinion forums, in the context of the movie industry. We then identify unusual patterns on Twitter that are consistent with sentiment manipulation. We study the effectiveness of social media advertising in the second essay. Advertisers on popular social media platforms such as Facebook are able to publish ads with popularity and social information. We design and conduct a randomized field experiment to study the extent to which these types of information have an effect on ad performance. In the third essay we study how individuals might be biased toward contents that appear to be written more politely. We use data from an online question answering platform, StackExchange, to show that an individual who posts a question on the platform tends to prefer polite answers to clear answers.Information, Risk, and Operations Management (IROM

Manipulation: Online Platforms’ Inescapable Fate

Online platforms are prone to abuse and manipulation from strategic parties. For example, social media and review websites suffer from the presence of opinion spam and fake reviews. Applying the economic concept of rational expectation equilibrium (REE), we explore the impact of manipulation on consumer welfare in a Twitter-like environment. We argue that the REE outcome can be decomposed into a firm-centric effect and a rational expectation effect, and the relative strength of these effects determines the final level of manipulation. We also examine the effect of competition on firms’ manipulation levels. We find that the combination of a competition effect and a rational expectation effect determines the overall effect of competition on strategic manipulation. This research sheds light on the reliability of opinion mining, and contributes to our understanding of strategic manipulation in the context of sentiment analysis

Incentive Provision and Pro-Social Behaviors

Individuals’ pro-social behaviors are driven by altruistic and selfish motivations. In this paper we explore how the introduction of external incentives would influence one’s pro-social behavior both in the short term and in the long run. Using a large data set on Amazon product reviews, we design a quasi-experimental approach where we combine a propensity score matching (PSM) and a difference-in-differences (DiD) method to empirically study the effect of incentive provision on reviewer’s behavior. We apply techniques from linguistics, language processing, and machine learning to propose several novel measures to capture reviews’ writing style and quality. We find evidences consistent with crowding-out and overjustification effects. Our study contributes to the understanding of pro-social behavior and sheds light on how incentives would shift individual behavior

COVID-19 Demand Shocks Revisited: Did Advertising Technology Help Mitigate Adverse Consequences for Small and Midsize Businesses?

Research has investigated the impact of the COVID-19 pandemic on business performance and survival, indicating particularly adverse effects for small and midsize businesses (SMBs). Yet only limited work has examined whether and how online advertising technology may have helped shape these outcomes, particularly for SMBs. The aim of this study is to address this gap. By constructing and analyzing a novel data set of more than 60,000 businesses in 49 countries, we examine the impact of government lockdowns on business survival. Using discrete-time survival models with instrumental variables and staggered difference-in-differences estimators, we find that government lockdowns increased the likelihood of SMB closure around the world but that use of online advertising technology attenuates this adverse effect. The findings show heterogeneity in country, industry, and business size, consistent with theoretical expectations

Consecutive Tumor Lysis Syndrome and Hepatic Failure after Transarterial Chemoembolization for Treatment of Hepatocellular Aarcinoma: A Case Report and Literature Review

Introduction: Acute tumor lysis syndrome (ATLS) and hepatic failure are fatal complications that can occur in patients with hepatocellular carcinoma (HCC) who undergo transarterial chemoembolization (TACE).Presentation of Case: We report the case of a 78-year-old man with HCC who had successive ATLS and hepatic failure after the first course of TACE. He succumbed due to rapid deterioration of his condition.Conclusion: We therefore concluded that awareness of the risks of ATLS and hepatic failure before administration of TACE is crucial in patients with HCC

The modulation of hypoxia-inducible factor-1α/plasminogen activator inhibitor-1 axis in human gingival fibroblasts stimulated with cyclosporine A

Background/PurposeThe prominent side effect of the immunosuppressive drug cyclosporine A (CsA) is gingival overgrowth. Hypoxia-inducible factor (HIF)-1α regulates a wide variety of profibrogenic genes, which are closely associated with tissue fibrosis. The aim of this study was to compare HIF-1α expression in normal gingival tissues and CsA-induced gingival overgrowth specimens and further explore the potential mechanisms that may lead to induction of HIF-1α expression.MethodsFifteen CsA-induced gingival overgrowth specimens and five normal gingival tissues were examined by immunohistochemistry. Western blot was used to investigate the effects of CsA on the expression of HIF-1α in cultured human gingival fibroblasts. The effects of CsA on plasminogen activator inhibitor (PAI)-1 expression were evaluated in environmental hypoxia.ResultsHIF-1α staining in gingival tissue was stronger in CsA-induced gingival overgrowth group than normal gingival group (p < 0.05). The expression of HIF-1α was significantly higher in CsA-induced gingival overgrowth specimens with higher levels of inflammatory infiltrates (p = 0.041). CsA was found to upregulate HIF-1α protein in a dose-dependent manner (p < 0.05). Hypoxia increased CsA-induced PAI-1 protein expression than normoxic conditions (p < 0.05).ConclusionThese results suggest that HIF-1α expression is significantly upregulated in CsA-induced gingival overgrowth specimens. The activation of HIF-1α may promote fibrogenesis by an increase of PAI-1 expression and a subsequent elevation of extracellular matrix production in gingival tissues

Transgenic Plants: Gene Constructs, Vector and Transformation Method

The human population has reached 7 billion by 2015 and is estimated to exceed 10 billion by the end of 2050. As such, crops which are the main food source must be produced at a higher pace in order to cater in tandem with the food demand. In the past, traditional plant breeders practice classical breeding techniques to propagate plants with desirable traits. However, traditional breeding technique lies in that only individuals of the same or closely related species can be crossbred. Moreover, traditional breeders will not be able to obtain traits which are not inherent within the gene pool of their target plants through classical breeding. With recent advancements in the field of genetic engineering, it is now possible to insert beneficial genes from a completely different species or even kingdom into a target plant, yielding transgenic plants with multiple ideal traits. To develop a transgenic plant, parameters such as vector constructions, transformation methods, transgene integration, and inheritance of transgene need to be carefully considered to ensure the success of the transformation event. Hence, this chapter aimed to provide an overview of transgenic plants’ development, its advantages and disadvantages, as well as its application for the betterment of mankind

Drosophila Sensory Neurons Require Dscam for Dendritic Self-Avoidance and Proper Dendritic Field Organization

SummaryA neuron's dendrites typically do not cross one another. This intrinsic self-avoidance mechanism ensures unambiguous processing of sensory or synaptic inputs. Moreover, some neurons respect the territory of others of the same type, a phenomenon known as tiling. Different types of neurons, however, often have overlapping dendritic fields. We found that Down's syndrome Cell Adhesion Molecule (Dscam) is required for dendritic self-avoidance of all four classes of Drosophila dendritic arborization (da) neurons. However, neighboring mutant class IV da neurons still exhibited tiling, suggesting that self-avoidance and tiling differ in their recognition and repulsion mechanisms. Introducing 1 of the 38,016 Dscam isoforms to da neurons in Dscam mutants was sufficient to significantly restore self-avoidance. Remarkably, expression of a common Dscam isoform in da neurons of different classes prevented their dendrites from sharing the same territory, suggesting that coexistence of dendritic fields of different neuronal classes requires divergent expression of Dscam isoforms