Essays In Information Economics

This dissertation is composed of three chapters on topics in information economics. They investigate how competition and limited information affect firms\u27 strategies in different markets. The first chapter focuses on the market for online platforms, and the other two chapters on the luxury goods market. The first chapter studies how competition between online platforms alters their incentives to comply with regulations through a unique empirical example: censorship via content removal by three major live-streaming platforms in China. Adopting an event study approach, I show that platforms of different sizes censor a different number of keywords with notably different delays. Motivated by the event study results, I develop and estimate a discrete choice model where the platform\u27s profit depends on its own censorship action as well as that of its competitors. The model allows me to conduct counterfactual analysis while accounting for the strategic interaction between platforms. I derive policy implications for regulating social media in both authoritarian regimes and western democracies. The second and third chapters, which I co-authored with Pinar Yildirim and Z. John Zhang, theoretically investigate two different signaling phenomena in the context of luxury goods market. The second chapter studies the linkage between high-quality counterfeits and an emerging trend of minimalist luxury, where the wealthy purposefully restrain from the consumption of luxury goods to separate themselves from the rest. The third chapter studies the optimal product line decision in combating high-quality counterfeits. We show that the mechanism through which the wealthy can still stand out is to purchase more units of authentic luxury goods leveraging the shopping economies of scope at authorized stores. Our analysis in both chapters draws managerial implications for luxury brands

Spectral Compressive Sensing with Model Selection

The performance of existing approaches to the recovery of frequency-sparse signals from compressed measurements is limited by the coherence of required sparsity dictionaries and the discretization of frequency parameter space. In this paper, we adopt a parametric joint recovery-estimation method based on model selection in spectral compressive sensing. Numerical experiments show that our approach outperforms most state-of-the-art spectral CS recovery approaches in fidelity, tolerance to noise and computation efficiency.Comment: 5 pages, 2 figures, 1 table, published in ICASSP 201

Conspicuous Consumption on the Long Tail: How can Luxury Brands Benefit from Counterfeits?

We study how luxury brands can use product line expansion as a strategy when facing a threat from the counterfeit market. Consumers who are status-conscious consider the benefits and costs of buying luxury items in order to strengthen the beliefs of others about their status. Our findings suggest that product line expansion strategy serves these high-end consumers and their motives to strengthen their status image. In a market with counterfeiters, consumers have an incentive to buy additional products in order to reduce the uncertainty of their status signals. Increasing consumption makes it harder for others to imitate status when authentic brands signal quality and status with higher precision compared to counterfeits. Since each luxury item purchased contributes to one\u27s status in a marginally declining fashion, it is rational for a luxury brand to expand its product line such that it maintains its core product and introduces peripheral products with lower status signalling benefits and prices. We further show that an increasing counterfeit market share can increase status-conscious consumers\u27 willingness to pay for luxury goods. As a result, presence of counterfeiters can increase the profit of a luxury brand

Development and validation of vectors containing multiple siRNA expression cassettes for maximizing the efficiency of gene silencing

BACKGROUND: RNA interference (RNAi) was originally identified as a biological process in which short double-stranded RNA (dsRNA) suppress the expression of genes complimentary to the dsRNA. This cellular intrinsic gene silencing mechanism has subsequently been developed as a useful tool for studies of gene function. A major strategy for producing small interfering RNA (siRNA) in cultured cells involves the use of siRNA expression vectors in which a RNA polymerase III (Pol III) promoter and transcription stop signal are designed to constitute a functional siRNA expression cassette for production of siRNA. However, most of the available vectors contain only one siRNA expression cassette. RESULTS: In order to maximize the efficiency and versatility of the vector-based siRNA approach, we have developed vectors containing multiple (up to six) tandem siRNA expression cassettes. Moreover, we demonstrated that these vectors can be used not only to produce different siRNA to simultaneously suppress the expression of multiple genes but also to maximize the silencing of a singe gene. CONCLUSION: The vectors containing multiple siRNA expression cassettes can serve as useful tools for maximizing the efficiency of gene silencing

Shapes of distal tibiofibular syndesmosis are associated with risk of recurrent lateral ankle sprains

Distal tibiofibular syndesmosis (DTS) has wide anatomic variability in depth of incisura fibularis and shape of tibial tubercles. We designed a 3-year prospective cohort study of 300 young physical training soldiers in an Army Physical Fitness School. Ankle computed tomography (CT) scans showed that 56% of the incisura fibularis were a "C" shape, 25% were a "1" shape, and 19% were a "Gamma"shape. Furthermore, we invited a randomly selected subcohort of 6 participants in each shape of DTS to undergo a three-dimensional (3D) laser scanning. The "1" shape group showed widest displacement range of the DTS in the y-axis, along with the range of motion (ROM) on the position more than 20 degrees of the ankle dorsiflexion, inversion and eversion. During the 3-year study period, 23 participants experienced recurrent lateral ankle sprains. 7 cases of the incisura fibularis were "C" shape, 13 cases were "1" shape, and 3 cases were "Gamma"shape. The "1" shape showed highest risk among the three shapes in incident recurrent lateral ankle sprains. We propose that it is possible to classify shapes of DTS according to the shapes of incisura fibularis, and people with "1" shape may have more risk of recurrent lateral ankle sprains

Ranolazine recruits muscle microvasculature and enhances insulin action in rats: Ranolazine, microvasculature and insulin action

Ranolazine, an anti-anginal compound, has been shown to significantly improve glycaemic control in large-scale clinical trials, and short-term ranolazine treatment is associated with an improvement in myocardial blood flow. As microvascular perfusion plays critical roles in insulin delivery and action, we aimed to determine if ranolazine could improve muscle microvascular blood flow, thereby increasing muscle insulin delivery and glucose use. Overnight-fasted, anaesthetized Sprague-Dawley rats were used to determine the effects of ranolazine on microvascular recruitment using contrast-enhanced ultrasound, insulin action with euglycaemic hyperinsulinaemic clamp, and muscle insulin uptake using 125I-insulin. Ranolazine's effects on endothelial nitric oxide synthase (eNOS) phosphorylation, cAMP generation and endothelial insulin uptake were determined in cultured endothelial cells. Ranolazine-induced myographical changes in tension were determined in isolated distal saphenous artery. Ranolazine at therapeutically effective dose significantly recruited muscle microvasculature by increasing muscle microvascular blood volume (∼2-fold, P < 0.05) and increased insulin-mediated whole body glucose disposal (∼30%, P= 0.02). These were associated with an increased insulin delivery into the muscle (P < 0.04). In cultured endothelial cells, ranolazine increased eNOS phosphorylation and cAMP production without affecting endothelial insulin uptake. In ex vivo studies, ranolazine exerted a potent vasodilatatory effect on phenylephrine pre-constricted arterial rings, which was partially abolished by endothelium denudement. In conclusion, ranolazine treatment vasodilatates pre-capillary arterioles and increases microvascular perfusion, which are partially mediated by endothelium, leading to expanded microvascular endothelial surface area available for nutrient and hormone exchanges and resulting in increased muscle delivery and action of insulin. Whether these actions contribute to improved glycaemic control in patients with insulin resistance warrants further investigation

Tuning ice nucleation with counterions on polyelectrolyte brush surfaces

Heterogeneous ice nucleation (HIN) on ionic surfaces is ubiquitous in a wide range of atmospheric aerosols and at biological interfaces. Despite its great importance in cirrus cloud formation and cryopreservation of cells, organs, and tissues, it remains unclear whether the ion-specific effect on ice nucleation exists. Benefiting from the fact that ions at the polyelectrolyte brush (PB)/water interface can be reversibly exchanged, we report the effect of ions on HIN on the PB surface, and we discover that the distinct efficiency of ions in tuning HIN follows the Hofmeister series. Moreover, a large HIN temperature window of up to 7.8°C is demonstrated. By establishing a correlation between the fraction of ice-like water molecules and the kinetics of structural transformation from liquid- to ice-like water molecules at the PB/water interface with different counterions, we show that our molecular dynamics simulation analysis is consistent with the experimental observation of the ion-specific effect on HIN