Abstract-We develop an approach to identify and test for bid rigging in procurement auctions. First, we introduce a general auction model with asymmetric bidders. Second, we study the problem of identi cation in our model. We state a set of conditions that are both necessary and suf cient for a distribution of bids to be generated by a model with competitive bidding. Third, we discuss how to elicit a prior distribution over a rm's structural cost parameters from industry experts. Given this prior distribution, we use Bayes's theorem to compare competitive and collusive models of industry equilibrium. Finally, we apply our methodology to a data set of bidding by construction rms in the Midwest. The techniques we propose are not computationally demanding, use exible functional forms, and can be programmed using most standard statistical packages.

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In many retail markets, prices rise faster than they fall. We develop a model of search with learning to explain this phenomenon of asymmetric price adjustments. By extending our static game analysis to the dynamic setting, we demonstrate that asymmetric price adjustments arise naturally. When a positive cost shock occurs, all the searchers immediately learn the true state; the search intensity, and hence the prices fully adjust in the next period. When a negative cost shock occurs, it takes longer for non-searchers to learn the true state, and the search intensity increases gradually, leading to slow falling of prices. __________________________ * The Ohio State University; yang.1041@osu.edu. * * The Ohio State University; lixinye@econ.ohio-state.edu.We thank Matt Lewis, Howard Marvel, James Peck, and the seminar participants in the Third Summer Savannah) for valuable comments and suggestions. We also benefit from insightful comments and suggestions from two anonymous referees. All remaining errors are our own.

We analyze costly quality disclosure with horizontally differentiated products under duopoly and a cartel, and characterize the effect of competition on disclosure and welfare. We show that expected disclosure is higher under a cartel than under duopoly, and the welfare comparison depends on the level of disclosure cost: when the disclosure cost is low, welfare is higher under a cartel than duopoly, but when the disclosure cost is high, welfare is higher under duopoly. In either market structure, disclosure is excessive in terms of total surplus, but insufficient in terms of consumer surplus. I INTRODUCTIONA free and efficient flow of information is important for modern, information driven economies. Although prices are the main carriers of information critical for decision making, important information is revealed to consumers directly by firms, either voluntarily or as mandated by law. For example, drug manufacturers must incur substantial costs in order to certify the safety and efficacy of new * We are very grateful to the editor and three anonymous referees for their insightful comments. All remaining errors are our own.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most common X-linked enzymopathies caused by G6PD gene variant. We aimed to provide the characteristics of G6PD deficiency and G6PD gene variant distribution in a large Chinese newborn screening population. We investigated the prevalence of G6PD in China from 2013 to 2017. Then, we examined G6PD activity and G6PD gene in representative Chinese birth cohort to explore the distribution of G6PD gene variant in 2016. We then performed multicolor melting curve analysis to classify G6PD gene variants in 10,357 neonates with activity-confirmed G6PD deficiency, and DNA

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Saturated hydraulic conductivity ( K s ) is one of the most important soil properties that determines water flow behavior in terrestrial ecosystems. However, the K s of forest soils is difficult to predict due to multiple interactions, such as anthropological and geomorphic processes. In this study, we examined the impacts of vegetation type on K s and associated mechanisms. We found that K s differed with vegetation type and soil depth, and the impact of vegetation type on K s was dependent on soil depth. K s did not differ among vegetation types at soil depths of 0–10 and 20–30 cm, but was significantly lower in managed forest types (mixed evergreen broad-leaved and coniferous forests, bamboo forests, and tea gardens) than native evergreen broadleaf forests at a depth of 10–20 cm. Boosted regression tree analysis indicated that total porosity, non-capillary porosity, and macro water-stable aggregates were the primary factors that influenced K s . Our results suggested that vegetation type was a key factor that influences hydraulic properties in subtropical forest soils through the alteration of soil properties, such as porosity and macro water-stable aggregates.