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para-Nitrophenyl Sulfate Activation of Human Sulfotransferase 1A1 Is Consistent with Intercepting the E·PAP Complex and Reformation of E·PAPS*

Tyapochkin, Eduard; Cook, Paul F.; Chen, Guangping
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
15.74%
Cytosolic sulfotransferase (SULT)-catalyzed sulfation regulates biological activities of various biosignaling molecules and metabolizes hydroxyl-containing drugs and xenobiotics. The universal sulfuryl group donor for SULT-catalyzed sulfation is adenosine 3′-phosphate 5′-phosphosulfate (PAPS), whereas the reaction products are a sulfated product and adenosine 3′,5′-diphosphate (PAP). Although SULT-catalyzed kinetic mechanisms have been studied since the 1980s, they remain unclear. Human SULT1A1 is an important phase II drug-metabolizing enzyme. Previously, isotope exchange at equilibrium indicated steady-state ordered mechanism with PAPS and PAP binding to the free SULT1A1 (Tyapochkin, E., Cook, P. F., and Chen, G. (2008) Biochemistry 47, 11894–11899). On the basis of activation of SULT1A1 by para-nitrophenyl sulfate (pNPS), an ordered bypass mechanism has been proposed where pNPS sulfates PAP prior to its release from the E·PAP complex regenerating E·PAPS. Data are consistent with uncompetitive substrate inhibition by naphthol as a result of formation of the E·PAP·naphthol dead-end complex; formation of the complex is corroborated by naphthol/PAP double inhibition experiments. pNPS activation data demonstrate an apparent ping-pong behavior with pNPS adding to E·PAP...

On the Communication Requirements of Verifying the VCG Outcome

Lahaie, Sébastien; Parkes, David C.
Fonte: Association for Computing Machinery Publicador: Association for Computing Machinery
Tipo: Monograph or Book
EN_US
Relevância na Pesquisa
55.98%
We consider the amount of communication required to verify the outcome of the Vickrey-Clarke-Groves (VCG) mechanism: an efficient allocation together with incentivizing VCG payments. We compare this to the communication required to verify the efficient decision rule alone, to assess the overhead imposed by VCG payments. Our characterizations are obtained by leveraging a connection between the VCG outcome and a price equilibrium concept known as universal competitive equilibrium. We consider four related environments within a common framework: the classic single-item setting, the multi-unit setting with decreasing marginal values, the classic assignment problem with unit-demand valuations, and the multi-unit assignment problem with substitutes valuations. We find that the single-unit settings have zero overhead, whereas the multi-unit settings can have significant positive overhead. With multiple units, the naïve VCG protocol that runs several efficient protocols in sequence (one with all agents, and ones with an agent removed, for each agent) is asymptotically optimal for several parameter settings of the number of agents, commodities, and units.; Engineering and Applied Sciences

Ascending Price Vickrey Auctions for General Valuations

Mishra, Debasis; Parkes, David C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
66.07%
Ascending price auctions involving a single price path and buyers paying their final bid price cannot achieve the Vickrey–Clarke–Groves (VCG) outcome in the combinatorial auctions setting. Using a notion called universal competitive equilibrium prices, shown to be necessary and sufficient to achieve the VCG outcome using ascending price auctions, we define a class of ascending price auctions in which buyers bid on a single price path. Truthful bidding by buyers is an ex post Nash equilibrium in such auctions. By giving discounts to buyers from the final price, the VCG outcome is achieved for general valuations.; Engineering and Applied Sciences

An Ascending-Price Generalized Vickrey Auction

Parkes, David C.; Ungar, Lyle H.
Fonte: Harvard University Publicador: Harvard University
Tipo: Conference Paper
EN_US
Relevância na Pesquisa
36.01%
A simple characterization of the equilibrium conditions required to compute Vickrey payments in the Combinatorial Allocation Problem leads to an ascending price Generalized Vickrey Auction. The ascending auc- tion, iBundle Extend & Adjust (iBEA), maintains non-linear and perhaps non-anonymous prices on bundles of items, and terminates with the ef- cient allocation and the Vickrey payments in ex post Nash equilibrium. Crucially, iBEA is able to implement the Vickrey outcome even when the Vickrey payments are not supported in a single competitive equilibrium. The auction closes with Universal competitive equilibrium prices, which provide enough information to compute individualized discounts to adjust the nal prices and implement Vickrey payments.; Engineering and Applied Sciences

Social Health Insurance for Developing Nations

Hsiao, William C.; Shaw, R. Paul
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
EN_US
Relevância na Pesquisa
25.74%
Good health is necessary for well-being but also has another critical impact: it causes poverty, in that large health expenditures can bankrupt families. Many nations are now hoping that formally mandated social health insurance (SHI), involving payroll taxes, will provide a solution. This report examines the principles, design, and practices of SHI for low and middle-income nations and the necessary conditions for its viability and sustainability, with a focus on design and implementation issues. This volume presents five country case studies to provide evidence and greater detail on key issues that arise at different stages of implementation in low-income countries. They have been selected to reflect on a continuum and timeline of operational stages, beginning with the initial design and legislation of SHI, the first phase of implementation, the expansion to cover larger segments of the population, and on up to completion, whereby SHI becomes the predominant form of health care financing in a country. Accordingly...

Modeling Services Liberalization : The Case of Tanzania

Jensen, Jesper; Rutherford, Thomas F.; Tarr, David G.
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
Relevância na Pesquisa
25.83%
This paper employs a 52-sector, small, open-economy computable general equilibrium model of the Tanzanian economy to assess the impact of the liberalization of regulatory barriers against foreign and domestic business service providers in Tanzania. The model incorporates productivity effects in both goods and services markets endogenously, through a Dixit-Stiglitz framework. It summarizes policy notes on the key business service sectors that were prepared for this work, and estimates the ad valorem equivalent of barriers to foreign direct investment based on these policy notes and detailed questionnaires completed by specialists in Tanzania. The authors estimate that Tanzania will gain about 5.3 percent of the value of Tanzanian consumption in the medium run (or about 4.8 percent of gross domestic product) from a full reform package that also includes uniform tariffs. The estimated gains increase to about 16 percent of consumption in the long-run, steady-state model, where the impact on the accumulation of capital from an improvement in the productivity of capital is taken into account. Decomposition exercises reveal that the largest gains to Tanzania will derive from liberalization of costly regulatory barriers that are non-discriminatory in their impacts between Tanzanian and multinational service providers.

Kazakhstan : Country Economic Memorandum, Getting Competitive, Staying Competitive, The Challenge of Managing Kazakhstan's Oil Boom

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Economic & Sector Work :: Country Economic Memorandum; Economic & Sector Work
ENGLISH; EN_US
Relevância na Pesquisa
25.9%
Kazakhstan has made substantial progress in its economic transition, and faces a potentially bright future thanks to its oil wealth. The challenge is to increase the country's competitiveness, and expand the benefits of growth, while avoiding the economic and social risks typically associated with oil wealth. The overarching theme of the report is how to exploit the strengths of the Kazakhstan economy in the new oil environment, while avoiding the pitfalls that oil income typically brings. The report provides benchmarks for key aspects of competitiveness in Kazakhstan vis a vis Ukraine, Russia, and the eight most recent members of the EU rather than with other rich countries. This is for two reasons: 1) Kazakhstan's strategic objectives are to level with the European Union (EU) over the long run in terms of living and production standards, and levels of productivity and income; and, 2) although oil and gas already represents a large portion of exports, it does not mean the direct impact of oil in Kazakhstan is as large as in, say, Saudi Arabia or Venezuela. The policy agenda needs to formulate detailed policies and public investments. In this regard, interventions in six broad areas must be developed and prioritized. The six areas discussed entail economic policy...

Multi-Item Vickrey-Dutch Auctions

Mishra, Debasis; Parkes, David C.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
35.83%
Descending price auctions are adopted for goods that must be sold quickly and in private values environments, for instance in flower, fish, and tobacco auctions. In this paper, we introduce efficient descending auctions for two environments: multiple non-identical items and buyers with unit-demand valuations; and multiple identical items and buyers with non-increasing marginal values. Our auctions are designed using the notion of universal competitive equilibrium (UCE) prices and they terminate with UCE prices, from which the Vickrey payments can be determined. For the unit-demand setting, our auction maintains linear and anonymous prices. For the homogeneous items setting, our auction maintains a single price and adopts Ausubel's notion of “clinching” to compute the final payments dynamically. The auctions support truthful bidding in an ex post Nash equilibrium and terminate with an efficient allocation. In simulation, we illustrate the speed and elicitation advantages of these auctions over their ascending price counterparts.; Engineering and Applied Sciences

Bead, Hoop, and Spring as a Classical Spontaneous Symmetry Breaking Problem

Ochoa, Fredy; Clavijo, Jorge
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/06/2005
Relevância na Pesquisa
15.74%
We describe a simple mechanical system that involves Spontaneous Symmetry Breaking. The system consists of two beads constrained to slide along a hoop and attached each other through a spring. When the hoop rotates about a fixed axis, the spring-beads system will change its equilibrium position as a function of the angular velocity. The system shows two different regions of symmetry separated by a critical point analogous to a second order transition. The competitive balance between the rotational diynamics and the interaction of the spring causes an Spontaneous Symmetry Breaking just as the balance between temperature and the spin interaction causes a transition in a ferromagnetic system. In addition, the gravitational potential act as an external force that causes explicit symmetry breaking and a feature of first-order transition. Near the transition point, the system exhibits a universal critical behavior where the changes of the parameter of order is described by the critical exponent beta =1/2 and the susceptibility by gamma =1. We also found a chaotic behavior near the critical point. Through a demostrative device we perform some qualitative observations that describe important features of the system.; Comment: 7 pages, 2 tables...

An Experimental Investigation of the Patterns of International Trade

Noussair, Charles N.; Plott, Charles R.; Riezman, Raymond G.
Fonte: American Economic Association Publicador: American Economic Association
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /06/1995
Relevância na Pesquisa
25.93%
This paper studies a laboratory economy with some of the prominent features of an international economic system. The patterns of trade and output predicted by the law of comparative advantage are observed evolving within the experimental markets. Market prices and quantities move in the direction of the competitive equilibrium, but the quantitative predictions of the (risk neutral) competitive equilibrium are rejected. Considerable amounts of economic activity occur as disequilibria. Factor-price equalization is observed, but there is a universal tendency for factors of production to trade at prices below their marginal products.