4,615 research outputs found
Unilateral and Exclusionary/Strategic Effects of Common Agency: Price Impacts in a Repeated Common Value English Auction
The business justification for multiple principals to hire a common agent is efficiency. Our empirical study demonstrates that the creation of the common agent unilaterally depresses winning bids. Additionally, the common agent was not only observed to be the dominant bidder but also paid significantly lower prices than fringe competitors (price/quantity differential). The observed price/quantity differential is consistent with the almost common value English auction theory developed by Rose and Kagel (2008) in which a cost advantaged bidder is able to reduce competition by credibly raising the costs of disadvantaged rivals associated with the winner’s curse.Common Value Auctions, Common Agency, Antitrust, Industrial Organization, D44, K21, K23,
Experience-Based Teaching Methods in Legal Counseling
Lawyers spend more time in their offices, in person-to-person encounters counseling troubled individuals, than in any other single area. The alternative to this is litigation, an expensive, inefficient, disfunctional process. Lawyers are counselors, in the most Sartrean sense of the word; whether they intend to be or not. Legal educators like Harrop Freeman and Andrew S. Watson, and legal psychologists such as Robert S. Redmount, have pointed out the inevitability of legal counseling in practice, and the lack of adequate preparation we give our students for their lives as counselors
Modelización de datos de supervivencia en nidos: estudio comparativo de varios métodos desarrollados recientemente que pueden implementarse en MARK y SAS
Estimating nest success and evaluating factors potentially related to the survival rates of nests are key aspects of many studies of avian populations. A strong interest in nest success has led to a rich literature detailing a variety of estimation methods for this vital rate. In recent years, modeling approaches have undergone especially rapid development. Despite these advances, most researchers still employ Mayfield’s ad–hoc method (Mayfield, 1961) or, in some cases, the maximum–likelihood estimator of Johnson (1979) and Bart & Robson (1982). Such methods permit analyses of stratified data but do not allow for more complex and realistic models of nest survival rate that include covariates that vary by individual, nest age, time, etc. and that may be continuous or categorical. Methods that allow researchers to rigorously assess the importance of a variety of biological factors that might affect nest survival rates can now be readily implemented in Program MARK and in SAS’s Proc GENMOD and Proc NLMIXED. Accordingly, use of Mayfield’s estimator without first evaluating the need for more complex models of nest survival rate cannot be justified. With the goal of increasing the use of more flexible methods, we first describe the likelihood used for these models and then consider the question of what the effective sample size is for computation of AICc. Next, we consider the advantages and disadvantages of these different programs in terms of ease of data input and model construction; utility/flexibility of generated estimates and predictions; ease of model selection; and ability to estimate variance components. An example data set is then analyzed using both MARK and SAS to demonstrate implementation of the methods with various models that contain nest–, group– (or block–), and time–specific covariates. Finally, we discuss improvements that would, if they became available, promote a better general understanding of nest survival rates.La estimación del éxito de nidificación y la evaluación de los factores potencialmente relacionados con las tasas de supervivencia de los mismos son aspectos clave de numerosos estudios sobre poblaciones de aves. El gran interés por el éxito de nidificación se ha traducido en una rica literatura que detalla varios métodos de estimación de esta tasa vital. En los últimos años, los enfoques de modelización han experimentado un rápido desarrollo. No obstante, pese a estos avances, la mayoría de los investigadores siguen empleando el método ad–hoc de Mayfield (Mayfield, 1961) o, en algunos casos, el estimador de probabilidad máxima de Johnson (1979) y Bart & Robson (1982). Tales métodos permiten el análisis de datos estratificados, pero, en cambio, no permiten modelos más complejos y realistas de la tasa de supervivencia en nidos cuando se incluyen covariantes que cambian según el individuo, la edad del nido, el tiempo, etc., y que pueden ser continuas o categóricas. Actualmente, con la ayuda de Program MARK, así como de Proc GENMOD y Proc NLMIXED de SAS, es posible implementar métodos que permiten a los investigadores evaluar rigurosamente la importancia de varios factores biológicos susceptibles de incidir en las tasas de supervivencia en nidos. Por consiguiente, no está justificada la utilización del estimador de Mayfield sin antes evaluar la necesidad de emplear modelos más complejos para determinar la tasa de supervivencia en nidos. Con objeto de incrementar el empleo de métodos más flexibles, primero describimos la probabilidad empleada para estos modelos, para posteriormente tomar en consideración cuál es el tamaño de muestra eficaz para el cálculo de AICc. Seguidamente, tomamos en consideración las ventajas y desventajas de estos programas por lo que respecta a la facilidad de introducción de datos y de construcción de modelos, la utilidad/flexibilidad de las estimaciones y predicciones generadas, la facilidad de la selección de modelos y la capacidad para estimar los componentes de la varianza. A continuación, analizamos un conjunto de datos de ejemplo utilizando los programas MARK y SAS con objeto de demostrar la implementación de los métodos con varios modelos que contienen nido–, grupo– (o bloque–), y covariantes específicas al tiempo. Por último, comentamos varias mejoras que, si estuvieran disponibles, fomentarían una mejor comprensión general de las tasas de supervivencia en nidos
Market-Oriented Strategies to Improve Household Access to Food: Experience from Sub-Saharan Africa
The objectives of this report are to identify market-oriented strategies to alleviate both chronic and transitory food insecurity, and to examine the interactions between short-run targeting mechanisms and longer-run strategies designed to alleviate the chronic causes of inadequate access to food. The main premise of the report is that sustained improvements in household access to food in Sub-Saharan Africa require the development of more reliable food and input markets that (a) create incentives to adopt cost-reducing investments at various stages in the food system; and (b) offer incentives for rural households to shift from a subsistence-oriented pattern of production and consumption to more productive systems based on specialization and gains from exchange. Sustained productivity growth in most parts of the world has typically entailed some form of structural transformation, which, in the historical development processes of other regions, has been a prerequisite for broad-based and sustained growth in productivity, real incomes and purchasing power throughout society. Structural transformation involves a movement away from subsistence-oriented, household-level production toward an integrated economy based on specialization and exchange. But specialization makes households dependent on the performance of exchange systems. The ability to capture the productivity gains from new technology and specialization thus depends on reducing the risks and uncertainty of market-based exchange, thereby facilitating greater participation in the types of specialized production and consumption patterns involved in the process of structural transformation. Section 3 presents empirical evidence from research conducted in Africa to draw conclusions about how the design of agricultural policies and transfer programs have affected household access to food in both rural and urban areas. Based on the foregoing, section 4 presents the following guidelines for the design of strategies to promote access to food in Africa: (1.) Focus on achieving productivity gains in the food system. (2.) Focus on how food and income transfer programs can be designed to promote the long-run development of the food system- the basis for providing food for most people over the long run in addition to providing food to people in the short run. (3.) Focus on reducing consumer food costs by expanding the range of products available to produce and consume. (4.) Focus on the cost and reliability of food supplies to rural areas as a component of non-farm, livestock, and other income diversification strategies designed to promote access to food over the longer run. (5.) Focus on developing local analytical expertise to help guide food system development.Food Security and Poverty, Downloads July 2008-June 2009: 12,
ENVIROSAT-2000 report: Federal agency satellite requirements
The requirement of Federal agencies, other than NOAA, for the data and services of civil operational environmental satellites (both polar orbiting and geostationary) are summarized. Agency plans for taking advantage of proposed future Earth sensing space systems, domestic and foreign, are cited also. Current data uses and future requirements are addressed as identified by each agency
Calcium ionophore (A-23187) induced peritoneal eicosanoid biosynthesis: a rapid method to evaluate inhibitors of arachidonic acid metabolism in vivo
The present investigation characterizes calcium ionophore (A-23187) induced peritoneal eicosanoid biosynthesis in the rat. Intraperitoneal injection of A-23187 (20 μg/rat) stimulated marked biosynthesis of 6-keto-PGF1α (6-KPA), TxB2, LTC4 and LTB4, with no detectable changes on levels of PGE2. Levels of all eicosanoids decreased rapidly after a peak which was seen as early as 5 min. Enzyme markers of cellular contents of neutrophils and mononuclear cells, MPO and NAG respectively, decreased rapidly after ionophore injection; this was followed by increases after 60 min. Indomethacin, a selective cyclooxygenase inhibitor, and zileuton and ICI D-2138, two selective 5-lipoxygenase inhibitors attenuated prostaglandin and leukotriene pathways respectively. Oral administration of zileuton (20 mg/kg, p.o.) inhibited LTB4 biosynthesis for up to 6 h suggesting a long duration of pharmacological activity in the rats consistent with its longer half-life. The rapid onset and the magnitude of increases in levels of eicosanoids render the ionophore induced peritoneal eicosanoid biosynthesis a useful model to evaluate pharmacological profiles of inhibitors of eicosanoid pathways in vivo
Irreversibility and Polymer Adsorption
Physisorption or chemisorption from dilute polymer solutions often entails
irreversible polymer-surface bonding. We present a theory of the
non-equilibrium layers which result. While the density profile and loop
distribution are the same as for equilibrium layers, the final layer comprises
a tightly bound inner part plus an outer part whose chains make only fN surface
contacts where N is chain length. The contact fractions f follow a broad
distribution, P(f) ~ f^{-4/5}, in rather close agreement with strong
physisorption experiments [H. M. Schneider et al, Langmuir v.12, p.994 (1996)].Comment: 4 pages, submitted to Phys. Rev. Let
Enabling Small-Scale Maize Marketing and Processing to Assure Supplies of Low-Cost Staples
Crop Production/Industries, Downloads December 2008 - July 2009: 6,
From Oxford to Bristol and Back: The Invention of Scientific Wildlife Television
In the 1960s, two scientists from Oxford University, Niko Tinbergen and Gerald Thompson, began using film as part of their scientific practice. The BBC’s Natural History Unit (NHU) in Bristol quickly got wind of their work and started collaborating with them to develop a new approach to wildlife television making. Tinbergen, the founder of ethology, brought intellectual foundations to it, creating, with Christopher Parsons, stories of wildlife informed by the theory of evolution. Thompson provided a technological edge which enabled the Bristol NHU producers to bring a new perspective to the subject matter they were showing in their programmes. The two collaborations also led them to further define their identity as experts in wildlife television making
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