Extracting Several Resource Deposits of Unknown Size: Optimal Order

Oil companies often announce revised estimates of their reserves. This indicates that stock uncertainty is a prevalent feature of natural resource industries. In this paper we consider the multi-deposit case where resource extraction produces information about the size of reserves. We show that the optimal order of extracting resource deposits depends both on the informational characteristics of the extraction process and on the extraction costs. Differences in extraction costs, a key consideration highlighted in Solow and Wan (1976), must be balanced against the relative value of information generated by the extraction of various deposits. Our model supplies an explanation of why high cost deposits are sometimes extracted when lower cost deposits have not been exhausted. Les compagnies pétrolières révisent souvent les chiffres de leurs réserves, ce qui indique que l’incertitude concernant les stocks est prévalente. Nous considérons le cas où l’extraction donne des informations sur la taille des réserves. Nous prouvons que l’ordre optimal d’exploitation des stocks dépend des propriétés du processus d’extraction concernant la révélation d’information et des coûts. La différence des coûts, qui est une considération importante dans Solow and Wan (1976), doit être balancée contre la valeur informative des réserves. Notre modèle fournit une explication du fait que les réserves plus coûteuses sont parfois exploitées avant l’épuisement des réserves moins coûteuses.order of extraction, value of information, uncertainty, ordre d’extraction, valeur de l’information, incertitude

Development Aid in the Presence of Corruption: Differential Games among Donors

In this paper, we complement the work of Kemp and Shimomura (2002) by considering the case of many donors playing a dynamic non-cooperative game of foreign aid. We consider two models. Model 1 deals with the case where donor countries continually feel the warm glow of from the act of giving. Model 2 postulates that donors will stop giving aid when a target level of development is reached. One of the main results of Model 1 is that there are multiple equilibria that can be Pareto ranked. Another interesting result is that an increase in the level of corruption in the recipient country will reduce the aid level of the low aid equilibrium, but increase that of the high aid equilibrium. In Model 2, the equilibrium strategies are non-linear functions of the level of development. The flow of aid falls at a faster and faster rate as the target is approached. An increase in corruption will increase the flow of aid in this model. On présente deux modèles d’aide internationale dans lesquels deux pays avancés s’engagent dans un jeu dynamique. Dans le premier modèle, les aides apportent aux donateurs des gains moraux. On montre qu’une hausse de la corruption du pays sous-développé peut augmenter les aides. Il y a une multiplicité d’équilibres de Nash, qui peuvent être ordonnés sous le critère de Pareto. Dans le deuxième modèle, les pays donateurs cessent de donner aussitôt que le niveau du développement atteint un but fixé. On montre que l’équilibre de ce modèle implique que le flux d’aide devient de plus en plus faible au fur et à mesure que le niveau de développement s’approche du but fixé. Les pays avancés donnent plus si le taux de corruption augmente.development aid, corruption, dynamic games, differential games, aide internationale, corruption, jeux dynamiques, jeux différentiels

A Differential Game Model of Tariff War

We present a simple two(-country) by two(-good) differental game model of international trade in which the governments of the two countries play a tariff-setting game. We explicitly derive a unilateral optimum tarifff rate and then a Markov-perfect equilibrium pair of tariff strategies (bilateral optimum tariff strategies) and compare the welfare level of each country among autarchic, free-trade, unilateral and bilateral optimum-tariff equilibria.Tariff-setting game, Durbale consumption good, Markov-perfect strategies, The rate of time preference

Structural determinants of the outer shell of β-carboxysomes in synechococcus elongatus PCC 7942: roles for CcmK2, K3-K4, CcmO, and CcmL

Cyanobacterial CO(2)-fixation is supported by a CO(2)-concentrating mechanism which improves photosynthesis by saturating the primary carboxylating enzyme, ribulose 1, 5-bisphosphate carboxylase/oxygenase (RuBisCO), with its preferred substrate CO(2). The site of CO(2)-concentration is a protein bound micro-compartment called the carboxysome which contains most, if not all, of the cellular RuBisCO. The shell of β-type carboxysomes is thought to be composed of two functional layers, with the inner layer involved in RuBisCO scaffolding and bicarbonate dehydration, and the outer layer in selective permeability to dissolved solutes. Here, four genes (ccmK2-4, ccmO), whose products were predicted to function in the outer shell layer of β-carboxysomes from Synechococcus elongatus PCC 7942, were investigated by analysis of defined genetic mutants. Deletion of the ccmK2 and ccmO genes resulted in severe high-CO(2)-requiring mutants with aberrant carboxysomes, whilst deletion of ccmK3 or ccmK4 resulted in cells with wild-type physiology and normal ultrastructure. However, a tandem deletion of ccmK3-4 resulted in cells with wild-type carboxysome structure, but physiologically deficient at low CO(2) conditions. These results revealed the minimum structural determinants of the outer shell of β-carboxysomes from this strain: CcmK2, CcmO and CcmL. An accessory set of proteins was required to refine the function of the pre-existing shell: CcmK3 and CcmK4. These data suggested a model for the facet structure of β-carboxysomes with CcmL forming the vertices, CcmK2 forming the bulk facet, and CcmO, a "zipper protein," interfacing the edges of carboxysome facets.The work was supported by an Australian National University PhD scholarship and partial funding from an Australian Research Council grant to GDP and MRB

Functions, Compositions, and Evolution of the Two Types of Carboxysomes: Polyhedral Microcompartments That Facilitate CO 2 Fixation in Cyanobacteria and Some Proteobacteria

Cyanobacteria are the globally dominant photoautotrophic lineage. Their success is dependent on a set of adaptations collectively termed the CO 2-concentrating mechanism (CCM). The purpose of the CCM is to support effective COCO2 fixation by enhancing th

Point X-ray sources in the SNR G 315.4-2.30 (MSH 14-63, RCW 86)

We report the results of a search for a point X-ray source (stellar remnant) in the southwest protrusion of the supernova remnant G 315.4-2.30 (MSH 14-63, RCW 86) using the archival data of the Chandra X-ray Observatory. The search was motivated by a hypothesis that G 315.4-2.30 is the result of an off-centered cavity supernova explosion of a moving massive star, which ended its evolution just near the edge of the main-sequence wind-driven bubble. This hypothesis implies that the southwest protrusion in G 315.4-2.30 is the remainder of a pre-existing bow shock-like structure created by the interaction of the supernova progenitor's wind with the interstellar medium and that the actual location of the supernova blast center is near the center of this hemispherical structure. We have discovered two point X-ray sources in the "proper" place. One of the sources has an optical counterpart with the photographic magnitude $13.38\pm0.40$, while the spectrum of the source can be fitted with an optically thin plasma model. We interpret this source as a foreground active star of late spectral type. The second source has no optical counterpart to a limiting magnitude $\sim 21$. The spectrum of this source can be fitted almost equally well with several simple models (power law: photon index $=1.87$; two-temperature blackbody: $kT_1 =0.11$ keV, $R_1 =2.34$ km and $kT_2 =0.71$ keV, $R_2 =0.06$ km; blackbody plus power law: $kT =0.07$ keV, photon index $=2.3$). We interpret this source as a candidate stellar remnant (neutron star), while the photon index and non-thermal luminosity of the source (almost the same as those of the Vela pulsar and the recently discovered pulsar PSR J 0205+6449 in the supernova remnant 3C 58) suggest that it can be a young "ordinary" pulsar.Comment: 7 pages, 6 figures,revised version accepted for publication in A&

Combating torture and other ill-treatment: a manual for action [2nd edition]

This manual seeks to support the global efforts to prevent and eradicate torture and other cruel, inhuman or degrading treatment or punishment (other ill-treatment). It is the second edition of Amnesty International’s Combating torture: A manual for action, first published in 2003. It updates the first edition by including recent developments in international law such as new treaties, standards, jurisprudence, findings and observations of human rights bodies, and expert opinions. It is designed to be a practical guide to international and regional standards that prohibit and seek to prevent torture and other ill-treatment worldwide. The manual provides advice on the implementation of these standards, drawing upon the ideas, activities and achievements of anti-torture activists and experts around the world. Amnesty International’s positions on specific issues are also provided. It is hoped that the manual will be of use not only to Amnesty International staff but to anyone working to expose and combat torture and other ill-treatment, including other human rights defenders, lawyers, judges, law enforcement officers and other public officials, legislators, health professionals and the media

What New Faculty Need to Know, But Don\u27t Know to Ask

A smooth transition to life at an academic institution and the surrounding community is essential to the professional careers of new faculty members. The transition begins during the hiring process and startup package negotiations. Once at an institution, aspects of academia including teaching, proposal writing, and the tenure process inevitably generate issues and concerns for new faculty members. Research has shown that mentoring new faculty members early in their academic career can have significant impact on professional success. This is especially true at a research-based institution where the demands of funded scholarship add an extra level of complexity. A survey was conducted of faculty members at Missouri University of Science & Technology (Missouri S&T) in their first three years of a tenure track appointment to determine areas of concern for new faculty members. This paper presents the survey results, discusses the issues raised by the survey, and makes recommendations for effective mentoring relationships. Specific questions for new faculty members discussed in this paper include: What to look for in a mentor? What to consider in selecting where to submit papers? When to say yes and when to say no to service? Where to begin the hunt for research funding? What are quality resources for teaching? The paper also provides insight to mentors relative to junior faculty members\u27 concerns. This paper evaluates issues that are critical to forming effective mentoring relationships. Guidance offered provides value to mentors in understanding which areas are of greatest concern to new faculty. It provides information to proteges as well in determining key characteristics of an effective mentor