Mobile application service networks: Apple’s App Store

In fast-moving and complex App Store, there is a need for exploring the content of mobile application services themselves. Thus, this research empirically analyzes the relationships among mobile application services to identify their structures and positions through a text-mining-based network analysis. Associations among categories and applications are visualized as macro-level category network and micro-level app network; network indexes gauge the structural properties and positional characteristics of each network. Mobile service categories are compared according to their values and grouped according to network properties using cluster analysis, offering implications for the sectoral characteristics of mobile services in App Store.     

Privacy and security concerns in online health services

There is a growing interest in Internet privacy and security concerns. This article investigates Internet privacy and security concerns to determine whether such concerns hinder online health service use under different policies that enhance privacy and security protection. Empirical findings show a negative association between online privacy and security concerns and the use of online health services. Regulations enhancing customers’ privacy and security moderate the negative relation.     

Convergent Validity of Contingent Behavior Responses in Models of Recreation Demand

Recreation demand modeling efforts are often limited by the range of variation in observed environmental quality. To address this limitation, the practitioners increasingly make use of contingent behavior (CB) data; i.e., asking survey respondents to forecast their trip patterns under hypothetical quality conditions. However, relatively little is known as to whether these stated responses are consistent with how households response to actual quality variation. The purpose of this paper is to investigate the convergent validity of CB data with observed trip patterns. Toward this end, we jointly model recreational lake usage in Iowa using observed and CB trip data collected from the 2004 Iowa Lake Survey. The Iowa lakes Survey collected three sets of trip data for 131 lakes in the state: (a) actual trips in 2004, (b) anticipated trips in 2005 to the same lakes given current lake conditions and (c) anticipated trips in 2005 given hypothetical improvements to a subset of the lakes. The three types of recreation demand data provide a unique opportunity to investigate the convergent validity of individual responses to actual versus hypothetical environmental conditions.     

Joint Taxation and the Labour Supply of Married Women: Evidence from the Canadian Tax Reform of 1988*

The Canadian federal tax reform of 1988 replaced a spousal tax exemption with a non‐refundable tax credit. This reduced the‘jointness’of the tax system: after the reform, secondary earners’effective‘first dollar’marginal tax rates no longer depended on the marginal tax rates of their spouses. In practice, the effective‘first dollar’marginal tax rates faced by women with high‐income husbands were particularly reduced. Using difference‐indifference estimators, we find a significant increase in labour force participation among women married to higher‐income husbands.     

Physical properties and degradability of PHB/chitosan blend films

Synthetic polymers are rarely degraded in nature and cause environmental pollution. Biodegradable films have been developed to alleviate the pollution. Many countries have great interests in biodegradable food packaging films. Poly (3‐hydroxy butyric acid) (PHB) is a natural biodegradable plastic with biocompatibility. However, PHB has some problems of application to the food system because it is brittle and stiff. Because PHB has a poor site for chemical modification, the blends of PHB with flexible polymers can overcome these undesirable properties. Therefore, we prepared the blend films of PHB with chitosan, analysed the mechanical properties and barrier properties against water vapour, oxygen and lipid and monitored biodegradability of PHB/chitosan films in this study. The degree of crystallinity of PHB/chitosan films by X‐ray diffraction decreased with increasing chitosan concentration. The granular sizes of the films were reduced with the addition of chitosan to the film in the micro structural observation by a scanning electron microscope. Mechanical properties, including tensile strength and percent elongation of the blend films increased with increasing chitosan ration in the films. It is demonstrated that mechanical properties of the films were improved by the addition of chitosan. The water vapour permeability (WVP) of the PHB film was the highest and WVP was decreased by the addition of chitosan. Oxygen permeability of the films decreased as chitosan amount increased. The films had very good barrier property against lipid. The consumed oxygen of PHB film was greater than that of chitosan film for incubation on the biodegradability determination of the films. Therefore, the blend films could be expected to increase the rate of degradation in natural environments.     

Net Neutrality,Network Capacity,and Innovation at the Edges

We study how net neutrality regulations affect a high‐bandwidth content provider (CP)'s investment incentives to enhance its quality of services in content delivery to end users. We find that the effects crucially depend on whether the CP's entry is constrained by the Internet service provider's network capacity. If the capacity is relatively large, the prioritization reduces the investment as CP's investment and prioritization form substitutes. With limited capacity, however, they become complements and the prioritization can facilitate the entry of congestion‐sensitive content. Our analysis suggests that the optimal policy may call for potentially asymmetric regulations across mobile and fixed networks.     

Uncertainty and the volatility forecasting power of option-implied volatility

This study investigates the impact of uncertainty on the volatility forecasting power of option-implied volatility. Option-implied volatility is a powerful predictor of future volatility, particularly during periods of high uncertainty. This is consistent with option-implied volatility being largely determined by volatility-informed traders (rather than directional traders) when uncertainty is high. New volatility forecasting models that incorporate such interaction outperform benchmark models, both in- and out-of-sample. The new models also better predict future volatility during the 2008 global financial crisis, for which benchmark models perform poorly. The results are robust to alternative choices of benchmark models, loss functions, and estimation windows.     

Cost-effectiveness of sequential urate lowering therapies for the management of gout in Singapore

Abstract

Aims: Allopurinol is the most common urate lowering therapy (ULT) used to treat gout but may cause life-threatening severe cutaneous adverse reactions (SCAR) in a small number of patients. Risk of SCAR is increased for patients with the HLA-B*58:01 genotype. When alternative ULT is required, febuxostat or probenecid are recommended. The aim of this study was to conduct a cost-utility analysis of sequential ULT treatment strategies for gout, including strategies with and without HLA-B*58:01 genotyping prior to treatment initiation, with a view to inform optimal gout management in Singapore.

Materials and methods: A Markov model was developed from the Singapore healthcare payer perspective. Reflecting local practice, 12 different treatment strategies containing at least one ULT (allopurinol, febuxostat, probenecid) were evaluated in adults with gout. Response rates (SUA < 6mg/dL) were derived from an in-house network meta-analysis and from published literature. Incremental cost-effectiveness ratios (ICERs) were calculated over a 30-year time horizon, with costs and benefits discounted at 3% per annum. Sensitivity analyses were conducted to explore uncertainties.

Results: Sequential treatment of allopurinol 300?mg/day-allopurinol 600?mg/day-probenecid (“standard of care”) was cost-effective compared to no ULT, with an ICER of SGD1,584/QALY. Allopurinol300-allopurinol600-probenecid-febuxostat sequence compared to allopurinol300-allopurinol600-probenecid had an ICER of SGD11,400/QALY. All other treatment strategies were dominated by preceding strategies. Treatment strategies incorporating HLA-B*58:01 genotyping before ULT use were dominated by the corresponding non-genotyping strategy.

Conclusions: Current standard of care (allopurinol300-allopurinol 600-probenecid) for gout is cost-effective compared with no ULT in the local context. Febuxostat is unlikely to be cost-effective in Singapore at current prices unless it is used last-line.     

Firms’ Beliefs and Learning: Models,Identification, and Empirical Evidence

Review of Industrial Organization - This paper reviews recent literature on structural models of oligopoly competition where firms have biased beliefs about the primitives of the model—e.g....     

How you see yourself influences your color preference: Effects of self-construal on evaluations of color combinations

The present study examines the role of self-construal in the preference for analogous versus complementary color combinations. The majority of previous research on color has been limited to exploration of single colors. However, designers and marketers often use a mix of colors whose harmony must be taken into consideration, which includes choosing whether to use colors placed next to each other on the color wheel (analogous combination) or to combine colors that are opposite each other (complementary combination). The current study proposes that self-construal influences the perception of and preference for color combinations. Individuals with interdependent self-construals tend to focus on relational similarity and value harmony, whereas individuals with independent self-construals tend to view objects as discrete and disconnected. Accordingly, the authors posited that individuals with interdependent self-construals would be more sensitive to the relationship between two colors and perceive analogous colors as more harmonious, thus preferring brands and products featuring analogous colors to those featuring complementary colors. Contrariwise, individuals with independent self-construals would display indifference in this regard. The hypotheses were confirmed in four studies employing various colors to form analogous and complementary color combinations.