Essays on within-platform competitive dynamics

This dissertation contains three studies on competitive dynamics within digital platforms. All of my three essays focus on platform complementors (producers of complementary products to the platform) and their competitive landscape within the platform. The empirical settings of my dissertation are based on novel datasets that I constructed from multiple sources in the context of the U.S. leading mobile platforms. The first study investigates the factors associated with performance in digital platforms’ complementor markets, focusing on two product strategies: a) the extent to which complementors imitate features from competitors’ products and b) their reaction speed to changes introduced by the platform owner. The paper suggests an inverted U-shaped relationship between imitation and performance. The analysis also finds that the speed by which complementors react to owner-induced changes is positively associated with product performance. The paper further identifies platform-wide contingent factors which moderate the hypothesized relationships. The second study explores the coopetitive dynamics within a platform. The paper explores under-researched competitive dynamics between a platform owner and its complementors, focusing on an owner’s entry into its complementors’ product space – a phenomenon termed as intra-platform envelopment in this paper. The analysis shows that the overall effect of intra-platform envelopment on complementor performance is negative with a pooled data of Apple and Google platforms together. However, interesting divergent effects are found when analyzing each platform separately. These differences can be explained by idiosyncratic platform characteristics, particularly differences in the way that platform owners implemented their intra-platform envelopment actions. Further, the effect of these actions is found to vary not only across platforms, but with complementor-specific characteristics within a given platform. The third study investigates platform complementors’ strategic decision process of innovation adoption within the platform. The paper conceptualizes and empirically shows how competitive rivalry shapes platform entrepreneurs’ propensity to adopt innovation brought by the platform owner – that is, a rule-setter of the institution. The analysis finds that competition generally discourages adoption. The adoption by peer rivals has an inverted U-shaped effect on adoption likelihood where decreasing curve is driven by competitive rivalry, and competition from the institutional rule-setter negatively affects adoption likelihood.2020-06-30T00:00:00

Only-Train-Once MR Fingerprinting for Magnetization Transfer Contrast Quantification

Magnetization transfer contrast magnetic resonance fingerprinting (MTC-MRF) is a novel quantitative imaging technique that simultaneously measures several tissue parameters of semisolid macromolecule and free bulk water. In this study, we propose an Only-Train-Once MR fingerprinting (OTOM) framework that estimates the free bulk water and MTC tissue parameters from MR fingerprints regardless of MRF schedule, thereby avoiding time-consuming process such as generation of training dataset and network training according to each MRF schedule. A recurrent neural network is designed to cope with two types of variants of MRF schedules: 1) various lengths and 2) various patterns. Experiments on digital phantoms and in vivo data demonstrate that our approach can achieve accurate quantification for the water and MTC parameters with multiple MRF schedules. Moreover, the proposed method is in excellent agreement with the conventional deep learning and fitting methods. The flexible OTOM framework could be an efficient tissue quantification tool for various MRF protocols.Comment: Accepted at 25th International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI'22

Latino Retail Entrepreneurship in Minnesota: Implications for Extension Educators

Minnesota has become a “new destination” state for Latino migrants in the United States. What has made Latinos in Minnesota successful? In a narrower sense, what has provided them with a route out of poverty and an alternative to unemployment or discrimination in the labor market? Our purpose was to (a) compile characteristics associated with the Latino community and successful Latino-owned retail businesses in Minnesota, (b) identify unique problems encountered by Latino retail entrepreneurs, and (c) develop recommendations to overcome obstacles encountered. To meet our objectives, we employed two methods: a Delphi study with Latino community leaders and a case study with Latino retail entrepreneurs. Implications for Extension educators are discussed

Effects of LGBT Nursing Education Using Simulation

PURPOSE: As health care needs for Lesbian, Gay, Bisexual and Transgender (LGBT) are becoming increasingly important, it has become imperative for the nurses to be attentive towards their health problems and provide nursing care with an open-minded attitude. Due to limited opportunity to provide direct nursing care to LGBT patients, it is hypothesized that simulation would provide good opportunity for students to experience LGBT nursing care in a safe environment. This study was conducted to develop and apply simulation of LGBT nursing care to ultimately provide unbiased nursing care for LGBT population and prepare basic data for LGBT nursing education. METHODS: This study was a single-group pre-post experimental design study for 57 senior nursing students based on the comparison of existing LGBT knowledge, general attitude towards LGBT, and nursing attitude towards LGBT before and after simulation. The scenario content included discussion of coming out issue, providing sexual health information, and supportive nursing care for LGBT population. Data were analyzed with descriptive statistics and Wilcoxon signed rank. RESULTS: Simulation education-led to a significant increase in LGBT knowledge and nursing attitude. However, there was no change in the general attitude towards LGBT. CONCLUSION: The results of this study suggest that LGBT education using simulation may be effective for nursing students and nurses from the point of concern for LGBT population. It is hypothesized that future LGBT educational programs might need more detailed information from both care recipients and nurses. Finally, LGBT education needs to be included in the nursing education curriculum

Blockade of Airway Inflammation by Kaempferol via Disturbing Tyk-STAT Signaling in Airway Epithelial Cells and in Asthmatic Mice

Asthma is characterized by bronchial inflammation causing increased airway hyperresponsiveness and eosinophilia. The interaction between airway epithelium and inflammatory mediators plays a key role in the asthmatic pathogenesis. The in vitro study elucidated inhibitory effects of kaempferol, a flavonoid found in apples and many berries, on inflammation in human airway epithelial BEAS-2B cells. Nontoxic kaempferol at ≤20 μM suppressed the LPS-induced IL-8 production through the TLR4 activation, inhibiting eotaxin-1 induction. The in vivo study explored the demoting effects of kaempferol on asthmatic inflammation in BALB/c mice sensitized with ovalbumin (OVA). Mouse macrophage inflammatory protein-2 production and CXCR2 expression were upregulated in OVA-challenged mice, which was attenuated by oral administration of ≥10 mg/kg kaempferol. Kaempferol allayed the airway tissue levels of eotaxin-1 and eotaxin receptor CCR3 enhanced by OVA challenge. This study further explored the blockade of Tyk-STAT signaling by kaempferol in both LPS-stimulated BEAS-2B cells and OVA-challenged mice. LPS activated Tyk2 responsible for eotaxin-1 induction, while kaempferol dose-dependently inhibited LPS- or IL-8-inflamed Tyk2 activation. Similar inhibition of Tyk2 activation by kaempferol was observed in OVA-induced mice. Additionally, LPS stimulated the activation of STAT1/3 signaling concomitant with downregulated expression of Tyk-inhibiting SOCS3. In contrast, kaempferol encumbered STAT1/3 signaling with restoration of SOCS3 expression. Consistently, oral administration of kaempferol blocked STAT3 transactivation elevated by OVA challenge. These results demonstrate that kaempferol alleviated airway inflammation through modulating Tyk2-STAT1/3 signaling responsive to IL-8 in endotoxin-exposed airway epithelium and in asthmatic mice. Therefore, kaempferol may be a therapeutic agent targeting asthmatic diseases

Respiratory Syncytial Virus-Like Nanoparticle Vaccination Induces Long-Term Protection Without Pulmonary Disease by Modulating Cytokines and T-cells Partially Through Alveolar Macrophages

The mechanisms of protection against respiratory syncytial virus (RSV) are poorly understood. Virus-like nanoparticles expressing RSV glycoproteins (eg, a combination of fusion and glycoprotein virus-like nanoparticles [FG VLPs]) have been suggested to be a promising RSV vaccine candidate. To understand the roles of alveolar macrophages (AMs) in inducing long-term protection, mice that were 12 months earlier vaccinated with formalin-inactivated RSV (FI-RSV) or FG VLPs were treated with clodronate liposome prior to RSV infection. FI-RSV immune mice with clodronate liposome treatment showed increases in eosinophils, plasmacytoid dendritic cells, interleukin (IL)-4+ T-cell infiltration, proinflammatory cytokines, chemokines, and, in particular, mucus production upon RSV infection. In contrast to FI-RSV immune mice with severe pulmonary histopathology, FG VLP immune mice showed no overt sign of histopathology and significantly lower levels of eosinophils, T-cell infiltration, and inflammatory cytokines, but higher levels of interferon-γ, which are correlated with protection against RSV disease. FG VLP immune mice with depletion of AMs showed increases in inflammatory cytokines and chemokines, as well as eosinophils. The results in this study suggest that FG nanoparticle vaccination induces long-term protection against RSV and that AMs play a role in the RSV protection by modulating eosinophilia, mucus production, inflammatory cytokines, and T-cell infiltration

Prevalence and characteristics of foodborne pathogens from slaughtered pig carcasses in Korea

The introduction of bacteria into slaughterhouses can lead to microbial contamination in carcasses during slaughter, and the initial level of bacteria in carcasses is important because it directly affects spoilage and the shelf life. This study was conducted to investigate the microbiological quality, and the prevalence of foodborne pathogens in 200 carcasses from 20 pig slaughterhouses across Korea. Distribution of microbial counts were significantly higher for aerobic bacteria at 3.01–4.00 log10 CFU/cm2 (42.0%) and 2.01–3.00 log10 CFU/cm2 (28.5%), whereas most of Escherichia coli showed the counts under 1.00 log10 CFU/cm2 (87.0%) (P < 0.05). The most common pathogen isolated from 200 carcasses was Staphylococcus aureus (11.5%), followed by Yersinia enterocolitica (7.0%). In total, 17 S. aureus isolates from four slaughterhouses were divided into six pulsotypes and seven spa types, and showed the same or different types depending on the slaughterhouses. Interestingly, isolates from two slaughterhouses carried only LukED associated with the promotion of bacterial virulence, whereas, isolates from two other slaughterhouses carried one or more toxin genes associated with enterotoxins including sen. In total, 14 Y. enterocolitica isolates from six slaughterhouses were divided into nine pulsotypes, 13 isolates belonging to biotype 1A or 2 carried only ystB, whereas one isolate belonging to bio-serotype 4/O:3 carried both ail and ystA. This is the first study to investigate microbial quality and the prevalence of foodborne pathogens in carcasses from slaughterhouses nationally, and the findings support the need for ongoing slaughterhouse monitoring to improve the microbiological safety of pig carcasses