Archaeal ubiquity

In the seventeenth century, Antoine von Leeuwenhook used a simple microscope to discover that we live within a previously undetected microbial world containing an enormously diverse population of creatures. The late nineteenth and early twentieth century brought advances in microbial culture techniques and in biochemistry, uncovering the roles that microbes play in all aspects of our world, from causing disease to modulating geochemical cycles. In the last 25 years, molecular biology has revealed the complexity and pervasiveness of the microbial world and its importance for understanding the interactions that maintain living systems on the planet. The paper by Preston et al. (1) in this issue of the Proceedings provides a clear illustration of the power of these molecular techniques to describe new biological relationships and to pose important questions about the mechanisms that drive evolution. The analysis of ribosomal RNA gene sequences is one molecular approach that has radically altered our view of microbial diversity. Its application can be extended and expedited by the use of PCR. The confluence of these techniques has stimulated the rapid assembly of sequence information from homologues rRNA gene regions derived from virtually all classes of organisms. The data collected thus far support the scheme first presented by Woese et al. (2), which holds that the relationships among organisms can be summarized in the form of a universal phylogenetic tree comprised of one eukaryotic and two prokaryotic domains: the Eucarya, the Bacteria, and the Archaea (Fig. 1)

Parton branching at amplitude level

We present an algorithm that evolves hard processes at the amplitude level by dressing them iteratively with (massless) quarks and gluons. The algorithm interleaves collinear emissions with soft emissions and includes Coulomb/Glauber exchanges. It includes all orders in $N_{\mathrm{c}}$, is spin dependent and is able to accommodate kinematic recoils. Although it is specified at leading logarithmic accuracy, the framework should be sufficient to go beyond. Coulomb exchanges make the factorisation of collinear and soft emissions highly non-trivial. In the absence of Coulomb exchanges, we show how factorisation works out and how a partial factorisation is manifest in the presence of Coulomb exchanges. Finally, we illustrate the use of the algorithm by deriving DGLAP evolution and computing the resummed thrust, hemisphere jet mass and gaps-between-jets distributions in $e^+ e^-$.Comment: 54 pages, minor changes in version

The Welfare Impact of Reducing Choice in Medicare Part D: A Comparison of Two Regulation Strategies

Motivated by widely publicized concerns that there are “too many” plans, we structurally estimate (and validate) an equilibrium model of the Medicare Part D market to study the welfare impacts of two feasible, similar-sized approaches for reducing choice. One reduces the maximum number of firm offerings regionally; the other removes plans providing donut hole coverage – consumers’ most valued dimension. We find welfare losses are far smaller when coupled with elimination of a dimension of differentiation, as in the latter approach. We illustrate our findings’ relevance under current health care reforms, and consider the merits of instead imposing ex ante competition for entry.

Do Incumbents Improve Service Quality in Response to Entry? Evidence from Airlines’ On-Time Performance

We examine if and how incumbent firms respond to entry, and entry threats, using non-price modes of competition. Our analysis focuses on service quality within the airline industry. We find that incumbent on-time performance actually worsens in response to entry, and even entry threats, by Southwest Airlines. Given Southwest’s general superiority in on-time performance, this result is consistent with equilibria of theoretical models of quality and price competition, which generally predict differentiation along quality. We corroborate this intuition with further analysis, showing there is no notable response by incumbents when an airline with average on-time performance (Continental) threatens to enter or enters a route.

The Welfare Impact of Reducing Choice in Medicare Part D: A Comparison of Two Regulation Strategies

Medicare’s prescription drug benefit (Part D) has been its largest expansion of benefits since 1965. Since the implementation of Part D, many regulatory proposals have been advanced in order to improve this government-created market. Among the most debated are proposals to limit the number of options, in response to concerns that there are “too many” plans. In this paper we study the welfare impact of two feasible approaches (of similar magnitude) toward limiting the number of Part D plans: reducing the maximum number of plans each firm can offer per region and removing plans that provide doughnut hole coverage. To this end, we propose and estimate a model of market equilibrium, which we later use to evaluate the impact of regulating down the number of Part D plans. Our counterfactuals provide an important assessment of the losses to consumers (and producers) resulting from government limitations on choice. These losses must be weighed against the widely discussed expected gains due to reduced search costs from limiting options. We find that the annual search costs should be at least two thirds of the average monthly premium in order to justify a regulation that allows only two plans per firm. However, this number would be substantially lower if the limitation in the number of plans is coupled with a decrease in product differentiation (e.g., by removing plans that cover the doughnut hole). For validation purposes, we also assess the impact of a recent major merger, and find that our model performs very well out of sample.Medicare Part D, regulation, number of plans, product differentiation, discrete choice

The impact of regulation, ownership and business culture on managing corporate risk within the water industry

Although the specifics of water utility ownership, regulation and management culture have been explored in terms of their impact on economic and customer value, there has been little meaningful engagement with their influence on the risk environment and risk management. Using a literature review as the primary source of information, this paper maps the existing knowledge base onto two critical questions: what are the particular features of regulation, ownership and management culture which influence the risk dynamic, and what are the implications of these relationships in the context of ambitions for resilient organizations? In addressing these queries, the paper considers the mindful choices and adjustments a utility must make to its risk management strategy to manage strategic tensions between efficiency, risk and resilience. The conclusions note a gap in understanding of the drivers required for a paradigm shift within the water sector from a re-active to a pro-active risk management culture. A proposed model of the tensions between reactive risk management and pro-active, adaptive risk management provides a compelling case for measured risk management approaches which are informed by an appreciation of regulation, ownership and business culture. Such approaches will support water authorities in meeting corporate aspirations to become "high reliability" services while retaining the capacity to out-perform financial and service level targets

Wine Taxes, Production, Aging and Quality

We consider the impact of taxes on the quantity and quality produced of goods, such as wine, for which market value accrues with age by a competitive producer. Any pair of taxes that includes a volumetric sales tax and any one of three other types of tax – an ad valorem sales tax, an ad valorem storage tax, or a volumetric storage tax – spans the full range of feasible tax revenues with positive tax rates. For any tax system that reduces quality relative to the firm’s no-tax equilibrium, there is another tax system that increases tax revenues, eliminates the quality distortion, and does not increase the quantity distortion. Many wine industry observers believe that most, if not all, existing tax systems tend to result in the suboptimal provision of quality. Our results suggest that the wide variety of wine tax systems is not prima facie evidence that these systems, or most of them, are inefficient. Provided the system includes a volumetric sales tax it may be efficient, regardless of which of the other instruments, or how many of them, are used. Assertions regarding inefficiency must be evaluated on an empirical case-by-case basis. Our analysis provides a theoretical framework for such research.aging, Alchian-Allen effect, tax policy, wine

Is Dual Agency in Real Estate Transactions a Cause for Concern?

We study dual agency in residential real estate, where the same agent/agency represents both the buyer and seller. We assess the extent to which dual agency suffers from an inherent conflict of interest, where the dual agent furthers the interest of one client at the expense of the other client’s, as well as principal-agent incentive misalignment where the agent furthers her own interest at the expense of one or both clients. And, we examine how these incentive conflicts affect agent behavior and transaction outcomes. To do so, we analyze 10,891 residential real estate transactions in Long Island, NY, from 2004- 2007. Specifically, we (i) identify how dual agency is correlated with house prices and time-to-sale, (ii) describe and assess agent behaviors that could generate these correlations, and (iii) provide some intuition as to the economic effects of prohibiting dual agency in real estate transactions. We find that the incidence of dual agency is uncorrelated with sale price and negatively correlated with time-to-sale. However, on very fast deals, list prices and sale prices are significantly higher on houses sold via dual agency. These findings are consistent with first-resort selling (agents first showing houses to in-house buyer clients) and strategic pricing (agents inducing their seller clients to set a higher list price in anticipation of an internal client agreeing to it) on some deals, in conjunction with agents leaning on sellers to accept a lower sale price on other deals. First-resort selling is indicative of incentive misalignment, while the latter two behaviors reflect a conflict of interest: strategic pricing transfers surplus from the buyer to the seller, and leaning on the seller transfers surplus from the seller to the buyer. Further, our results indicate little difference between dual-agent (same agent) and within-agency (same agency, but different agent) deals. Our findings provide some evidence of distorted outcomes associated with dual agency, mainly on fast deals, but the evidence indicates mild overall effects, suggesting that prohibiting the practice is not likely to substantially increase welfare.