We provide a model in which consumers search for firms directly or through platforms. Platforms lower search costs but charge firms for the transactions they facilitate. Platform fees raise the possibility of showrooming, in which consumers search on a platform but then switch and buy directly to take advantage of lower direct prices. In settings like this, search platforms like Booking.com have adopted price parity clauses, requiring firms to offer their best prices on the platform, arguing this is needed to prevent showrooming. However, despite allowing for showrooming in our model, we find that price parity clauses often harm consumers.

We study welfare effects of horizontal mergers under a successive oligopoly model and find that downstream mergers can increase welfare if they reduce input prices. The lower input price shifts some input production from costinefficient upstream firms to cost-efficient ones. Also, the lower input price makes upstream entry less attractive, reduces the number of upstream entrants, and decreases their average costs in the presence of fixed entry costs. We identity necessary and sufficient conditions for a reduction in input prices and welfare-improving horizontal mergers under a general demand function. Qualitative nature of our findings remains unchanged for upstream mergers.

In this paper we study the optimal monetary and fiscal policies of a general equilibrium model of unemployment and money with search frictions both in labor and goods markets as in Berentsen, Menzio and Wright (2010). We abstract from revenue-raising motives to focus on the welfare-enhancing properties of optimal policies. We show that some of the inefficiencies in the Berentsen, Menzio and Wright (2010) framework can be restored with appropriate fiscal policies. In particular, when lump sum monetary transfers are possible, a production subsidy financed by money printing can increase output in the decentralized market and a vacancy subsidy financed by a dividend tax even when the Hosios' rule does not hold. JEL Classification: E52, E63.

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This article examines a monopoly firm's incentive to disclose information through advertising when consumers can choose between buying immediately and searching for additional information. Because sales drop when search reveals low match values to consumers, the firm has an incentive to deter search. We show that partial information disclosure emerges as a useful tool for search deterrence when search costs are low. Informative advertising and consumer search can be viewed as complements in producing information. Although transparency policies reduce search expenditures and improve purchase decisions, whether they are socially desirable depends on the magnitude of search costs.

Copper nanoparticles are low-cost plasmonic materials with the ability of manipulating light at the nanometer scale. The exploration of copper nanoparticles toward photonic applications suffers instability due to the easy prone oxidation. In this paper, we developed the in situ formation of copper nanoparticles with a diameter between 40 and 50 nm in a natural plagioclase mineral crystal matrix by controlling the Cu+–Na+ ion exchange process in the temperature range of 1050–1200 °C. By combining quantitative element distribution characterization and spectroscopic measurement, we illustrate the in situ formation process and mechanism of Cu nanoparticles in natural plagioclase mineral crystals. Moreover, we determined the nonlinear optical properties of the materials by using the picosecond Z-scan technique. The third-order nonlinear optical susceptibility χ(3) at 1064 and 532 nm was estimated to be (1.046 ± 0.213) × 10–10 esu and (3.236 ± 0.198) × 10–10 esu, respectively. The natural plagioclase mineral crystals embedded with copper nanoparticles are believed to hold great potential to serve as plasmonic materials for a variety of practical applications, especially in nonlinear optics.

Imperfect observability and costly informative advertising are introduced into a standard directed search framework. Capacity-constrained sellers send costly advertisements to direct buyers' uncoordinated search by specifying their location and terms of trade. We show that the equilibrium advertising intensity is nonmonotonic in the buyer-seller ratio. In addition, we also find that price posting dominates auctions since both mechanisms yield the same expected revenue, but the latter results in higher advertising expense. Finally, we find a positive comovement between market transparency and price for low market tightness when the measure of informed buyers is endogenous. * Manuscript

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