A Ricardian Model of the Tragedy of the Commons

Nous étudions la tragédie des richesses communes dans un cadre où des agents qui diffèrent par leurs capacités productives et par leurs aptitudes à la prédation, choisissent d'allouer leur temps entre ces deux activités. Sous des hypothèses peu restrictives sur les technologies, les revenus attendus d'un agent sont convexes par rapport à ses actions, si bien que les individus se spécialisent et que la société se divise, à l'équilibre, en deux groupes au maximum: les prédateurs et les producteurs. La répartition s'opère selon un critère d'avantage comparatif. Il y a plusieurs équilibres. La tragédie des richesses communes (aucun producteur) est toujours l'un d'eux; l'allocation Pareto optimale pas toujours. Nous montrons que des changements mineurs dans la mise en vigueur des droits de propriété peuvent mener à des améliorations majeures pour la société. Les jeux convexes tels celui-ci appellent l'hypothèse de rationalité limitée; nous introduisons un concept d'équilibre de Nash local qui en est le pendant analytique naturel.This paper revisits the tragedy of the commons when agents have different capabilities in both production and encroachment activities, and can allocate their time between them. Under fairly general assumptions on production and encroachment technologies, an individual's expected income is convex with respect his actions so that individuals specialize. Consequently, in equilibrium, the economy is divided into at most two homogenous groups: encroachers and producers. The partition obeys a relative advantage criterion. Several equilibria may exist. The tragedy of the commons equilibrium without production always does; the Pareto optimal allocation of activities may not be an equilibrium. We show that minute changes in property right enforcement may lead to drastic improvements for society. We argue that, in convex games such as this paper's role choice game, bounded rationality is a natural assumption, and the concept of local Nash equilibrium is the natural analytical tool to handle it

A Ricardian Model of the tragedy of the Commons

This paper revisits the tragedy of the commons when agents have different capabilities in both production and encroachment activities, and can allocate their time between them. Under fairly general assumptions on production and encroachment technologies, an individual's expected income is convex with respect his actions so that individuals specialize. Consequently, in equilibrium, the economy is divided into at most two homogenous groups: encroachers and producers. The partition obeys a relative advantage criterion. Several equilibria may exist. The 'tragedy of the commons' equilibrium without production always does; the Pareto optimal allocation of activities may not be an equilibrium. We show that minute changes in property right enforcement may lead to drastic improvements for society. We argue that, in convex games such as this paper's role choice game, bounded rationality is a natural assumption, and the concept of local Nash equilibrium is the natural analytical tool to handle it. Nous étudions la tragédie des richesses communes dans un cadre où des agents qui diffèrent par leurs capacités productives et par leurs aptitudes à la prédation, choisissent d'allouer leur temps entre ces deux activités. Sous des hypothèses peu restrictives sur les technologies, les revenus attendus d'un agent sont convexes par rapport à ses actions, si bien que les individus se spécialisent et que la société se divise, à l'équilibre, en deux groupes au maximum: les prédateurs et les producteurs. La répartition s'opère selon un critère d'avantage comparatif. Il y a plusieurs équilibres. La tragédie des richesses communes (aucun producteur) est toujours l'un d'eux; l'allocation Pareto optimale pas toujours. Nous montrons que des changements mineurs dans la mise en vigueur des droits de propriété peuvent mener à des améliorations majeures pour la société. Les jeux convexes tels celui-ci appellent l'hypothèse de rationalité limitée; nous introduisons un concept d'équilibre de Nash local qui en est le pendant analytique naturel.Property rights, institutions, commons, convex games, general equilibrium, bounded rationality - droits de propriété, propriété commune, jeux convexes, équilibre général, rationalité limitée

Optimal Justice in a General Equilibrium Model with Non Observable Individual Productivities

In this general equilibrium model, justice and police institutions are treated as a mechanism that induces individuals to extend some desirable productive effort. This determines individual encroachment activities which in turn determine the proportion of aggregate production that fails to be appropriated, and the private incentives to choose productive activities. Since individuals have different productive abilities society would ideally take both equity and efficiency into consideration in the design of its institutions: encroachment is a form of redistribution from the most talented individuals to the least talented ones. We study the stylized properties that should arise when individual productivities are not observable by the system, and when both detection levels and justice accurary are costly instruments. Nous étudions dans un modèle d'équilibre général le rôle du système judiciaire comme instrument d'allocation des activités de production et de prédation. Les décisions individuelles se prennent compte tenu, à la fois des sentences que l'on peut escompter à la suite d'activités prohibées, et de la mesure dans laquelle, à l'équilibre, les producteurs peuvent s'approprier le fruit de leurs efforts. Comme les capacités productives diffèrent d'une personne à l'autre, il est socialement désirable de prendre en compte des considérations d'équité et d'efficacité dans la conception des institutions : la prédation est une forme de redistribution des plus productifs vers les moins productifs. Nous étudions les faits stylisés qui caractériseraient un tel système lorsque les productivités individuelles ne sont pas observables et que tant le niveau de détection que la précision des décisions de justice sont des caractéristiques coûteuses des institutions.Justice, institutions, incentives, crime, information, observability, agency, general equilibrium, Justice, institutions, incitations, crime, information, observabilité, agence, équilibre général

A Ricardian Model of the Tragedy of the Commons

This paper revisits the tragedy of the commons when agents have different capabilities in both production and encroachment activities, and can allocate their time between them. Under fairly general assumptions on production and encroachment technologies, an individual's expected income is convex with respect his actions so that individuals specialize. Consequently, in equilibrium, the economy is divided into at most two homogenous groups: encroachers and producers. The partition obeys a relative advantage criterion. Several equilibria may exist. The tragedy of the commons equilibrium without production always does; the Pareto optimal allocation of activities may not be an equilibrium. We show that minute changes in property right enforcement may lead to drastic improvements for society. We argue that, in convex games such as this paper's role choice game, bounded rationality is a natural assumption, and the concept of local Nash equilibrium is the natural analytical tool to handle it. Nous étudions la tragédie des richesses communes dans un cadre où des agents qui diffèrent par leurs capacités productives et par leurs aptitudes à la prédation, choisissent d'allouer leur temps entre ces deux activités. Sous des hypothèses peu restrictives sur les technologies, les revenus attendus d'un agent sont convexes par rapport à ses actions, si bien que les individus se spécialisent et que la société se divise, à l'équilibre, en deux groupes au maximum: les prédateurs et les producteurs. La répartition s'opère selon un critère d'avantage comparatif. Il y a plusieurs équilibres. La tragédie des richesses communes (aucun producteur) est toujours l'un d'eux; l'allocation Pareto optimale pas toujours. Nous montrons que des changements mineurs dans la mise en vigueur des droits de propriété peuvent mener à des améliorations majeures pour la société. Les jeux convexes tels celui-ci appellent l'hypothèse de rationalité limitée; nous introduisons un concept d'équilibre de Nash local qui en est le pendant analytique naturel.Property rights, institutions, commons, convex games, general equilibrium, bounded rationality, Droits de propriété, institutions, propriété commune, jeux convexes, équilibre général, rationalité limitée

Early Initiation of Highly Active Antiretroviral Therapies (HAART) for HIV/aids: The Contribution of a Stochastic Dynamic Model of Choice

Criteria for initiation of highly active antiretroviral treatments (HAART) in HIV-infected patients remain a matter of debate world-wide because short-term benefits have to be balanced with costs of these therapies, and restrictions placed on future treatment options if resistant viral strains develop. In order to take into account irreversibility and inertia effects associated with ex ante choices, we propose a simple stochastic dynamic model of sequential therapeutic choice with intermediary revelation of information, in which the efficiency gains from a new effective Therapy in second period are conditional on the results of the treatment in the previous period. We find that identical patients may be administered different treatments at the optimum; for parameters implying an all or nothing cut decision in period 2, a more forward looking decision rule is required in period 1 because there will be little space for adjustment to its consequences. Another finding is that as soon as risks of resistance due to therapeutic failure of initial treatments are significant, as perhaps in developing countries and in marginalized groups of developed countries, differences in the estimation of this risk should not influence the optimal decision about the size of the HIV-infected population eligible for early antiretroviral Therapy. The decision should then be based on pure efficiency/cost considerations. Le bien-fondé d'administrer précocement des traitements antirétroviraux à haute activité (HAART) aux personnes infectées par le VIH reste l'objet de débats dans le monde car leurs bienfaits à court terme peuvent compromettre les traitements futurs si des souches résistantes du virus se développent. Nous formulons un modèle qui combine irréversibilité et inertie dans un cadre de décision thérapeutique séquentielle. L'information se révèle entre la première et la deuxième période, si bien que la décision thérapeutique de deuxième période est conditionnelle à cette information. Il s'avère que des patients identiques peuvent se voir administrer des traitements différents à l'optimum; de plus, pour des paramètres justifiant des décisions bien tranchées en période 2 (à patients identiques traitement identique), la décision de période 1 est plus complexe car il est alors trop tard pour en renverser les conséquences en période 2. Autre résultat: supposons que le risque de résistance est élevé en cas d'échec thérapeutique du traitement initial (pays en développement; groupes défavorisés); nous montrons alors que les différences dans l'estimation de ce risque n'interviennent pas dans le choix optimal de la taille de la population qui se voit administrer le traitement antirétroviral. L'introduction du traitement relève alors purement de considérations d'efficacité et de coût.therapeutic decisions, uncertainty, information, irreversibility, treatment, learning, errors, décisions thérapeutiques, incertitude,information, irréversibilité, traitement, apprentissage, erreurs

Early Initiation of Highly Active Antiretroviral Therapies for Aids: Dynamic choice with Endogenous and Exogenous Learning

Criteria for initiation of highly active antiretroviral treatments (HAART) in HIV-infected patients remain a matter of debate world-wide because short-term benefits have to be balanced with costs of these therapies, and restrictions placed on future treatment options if resistant viral strains develop. On the other hand, postponing the introduction of HAART may involve a therapeutic opportunity cost if a patient’s health is allowed to deteriorate to such an extent of becoming unable to benefit from new treatments currently under development when they become available. We introduce a two period model where period one treatment adoption is an irreversible act with future, but uncertain, consequences. New information, both endogenous and exogenous, arises over time and shapes the conditions surrounding the second period therapeutic decision. A surprising result is that, under conditions that appear close to those surrounding the HAART debate, the magnitude of the feared resistance effect has no effect on leaves the optimal treatment decision as far as it is high enough. Le bien-fondé d’administrer précocement des traitements antirétroviraux à haute activité (HAART) aux personnes infectées par le VIH reste objet de débats dans le monde, car leurs bienfaits à court terme peuvent compromettre les traitements futurs si se développent des souches résistantes du virus. Par ailleurs retarder le recours aux HAART comporte un coût d’opportunité thérapeutique si la santé du patient se dégrade au point qu’il ne peut plus bénéficier par la suite des traitements encore en cours de développement. Nous formulons un modèle à deux périodes où l’adoption du traitement de première période est irréversible et engage le futur, alors que des informations et connaissances nouvelles, exogènes et endogènes, déterminent les conditions entourant la décision thérapeutique de deuxième période. Paradoxalement, sous des conditions reflétant bien les enjeux du recours aux HAART, il s’avère que l’effet résistance éventuel a d’autant moins de chance d’importer pour la décision optimale, que sa gravité est élevée.therapeutic decisions, uncertainty, information, irreversibility, treatment, endogenous learning, exogenous learning, décisions thérapeutiques, incertitude, information, irréversibilité, traitement, apprentissage endogène, apprentissage exogène

Optimal Justice in a General Equilibrium Model with Non Observable Individual Productivities

Nous étudions dans un modèle d'équilibre général le rôle du système judiciaire comme instrument d'allocation des activités de production et de prédation. Les décisions individuelles se prennent compte tenu, à la fois des sentences que l'on peut escompter à la suite d'activités prohibées, et de la mesure dans laquelle, à l'équilibre, les producteurs peuvent s'approprier le fruit de leurs efforts. Comme les capacités productives diffèrent d'une personne à l'autre, il est socialement désirable de prendre en compte des considérations d'équité et d'efficacité dans la conception des institutions : la prédation est une forme de redistribution des plus productifs vers les moins productifs. Nous étudions les faits stylisés qui caractériseraient un tel système lorsque les productivités individuelles ne sont pas observables et que tant le niveau de détection que la précision des décisions de justice sont des caractéristiques coûteuses des institutions.In this general equilibrium model, justice and police institutions are treated as a mechanism that induces individuals to extend some desirable productive effort. This determines individual encroachment activities which in turn determine the proportion of aggregate production that fails to be appropriated, and the private incentives to choose productive activities. Since individuals have different productive abilities society would ideally take both equity and efficiency into consideration in the design of its institutions: encroachment is a form of redistribution from the most talented individuals to the least talented ones. We study the stylized properties that should arise when individual productivities are not observable by the system, and when both detection levels and justice accurary are costly instruments

Exploring Determinants of Interdisciplinary Collaboration within a Geriatric Oncology Setting: A Mixed-Method Study

Therapeutic challenges regarding the population of elderly cancer patients and their heterogeneity lead to the need to implement person-centered approaches in order to optimize care strategies and adapt oncology treatments to each pattern of aging. The International Society of Geriatric Oncology recommends a multidisciplinary evaluation of these patients and the use of screening tools prior to the initiation of treatments. However, previous research shows a poor implementation of these recommendations in geriatric oncology. Although some studies have identified how different perceptions of geriatric oncology might hinder routine teamwork, little is known about the impact of other factors on promoting the collaboration between the two specialties. This mixed-method exploratory study used an online questionnaire to assess the perception of a group of 22 geriatricians and oncology physicians on different determinants of oncology care and teamwork. In this sample, older oncology patients benefited from geriatric care. However, there was a variability regarding age criteria and a limited use of screening tools. The multidimensional framework for interprofessional teamwork by Reeves has been used to analyze some of the determinants of the collaboration between oncology physicians and geriatricians. This study has identified systematic issues to consider when promoting communication and common values between the two disciplines, including available resources in terms of shared time, space and routine actions

Calcium Independent Effect of Orai1 and STIM1 in Non-Hodgkin B Cell Lymphoma Dissemination

International audienceCa 2+ release-activated Ca 2+ channels, composed of Orai1 and STIM1 (stromal interaction molecule 1) proteins, are the main Ca 2+ entry mechanism in lymphocytes. Their role in cell migration and metastasis is demonstrated in solid cancers but it remains elusive in malignant hemopathies. Diffuse large B cell lymphoma (DLBCL) is characterized by the dissemination of neoplastic B cells throughout the organism which is under the control of chemokines such as Stromal Derived Factor 1 (SDF-1) and its receptor CXCR4. CXCR4 activation triggers a complex intracellular signaling including an increase in intracellular Ca 2+ concentration whose role is still unclear. Using pharmacological and genetic approaches, we revealed that STIM1 and Orai1 were responsible for Ca 2+ influx induced by SDF-1. Furthermore, we provide in vitro and in vivo evidence that they are necessary for basal or SDF-1-induced DLBCL cell migration which is independent of Ca 2+ entry. We identify that they act as effectors coupling RhoA and ROCK dependent signaling pathway to MLC2 phosphorylation and actin polymerization. Finally, we revealed an alteration of Orai1 and STIM1 expression in extra-nodal DLBCL. Thus, we discovered a novel Ca 2+-independent but Orai1 and STIM1-dependent signaling pathway involved in basal and CXCR4 dependent cell migration, which could be relevant for DLBCL physiopathology

Patient Preferences for Treatment Outcomes in Oncology with a Focus on the Older Patient:A Systematic Review

SIMPLE SUMMARY: In oncology, treatment outcomes can be competing, which means that one treatment could benefit one outcome, like survival, and negatively influence another, like independence. The choice of treatment therefore depends on the patient’s preference for outcomes, which needs to be assessed explicitly. Especially in older patients, patient preferences are important. Our systematic review summarizes all studies that assessed patient preferences for various treatment outcome categories. A total of 28 studies with 4374 patients were included, of which only six studies included mostly older patients. Although quality of life was only included in half of the studies, overall quality of life (79%) was most frequently prioritized as highest or second highest, followed by overall survival (67%), progression- and disease-free survival (56%), absence of severe or persistent treatment side effects (54%), treatment response (50%), and absence of transient short-term side effects (16%). In shared decision-making, these results can be used by healthcare professionals to better tailor the information provision and treatment recommendations to the individual patient. ABSTRACT: For physicians, it is important to know which treatment outcomes are prioritized overall by older patients with cancer, since this will help them to tailor the amount of information and treatment recommendations. Older patients might prioritize other outcomes than younger patients. Our objective is to summarize which outcomes matter most to older patients with cancer. A systematic review was conducted, in which we searched Embase and Medline on 22 December 2020. Studies were eligible if they reported some form of prioritization of outcome categories relative to each other in patients with all types of cancer and if they included at least three outcome categories. Subsequently, for each study, the highest or second-highest outcome category was identified and presented in relation to the number of studies that included that outcome category. An adapted Newcastle–Ottawa Scale was used to assess the risk of bias. In total, 4374 patients were asked for their priorities in 28 studies that were included. Only six of these studies had a population with a median age above 70. Of all the studies, 79% identified quality of life as the highest or second-highest priority, followed by overall survival (67%), progression- and disease-free survival (56%), absence of severe or persistent treatment side effects (54%), and treatment response (50%). Absence of transient short-term side effects was prioritized in 16%. The studies were heterogeneous considering age, cancer type, and treatment settings. Overall, quality of life, overall survival, progression- and disease-free survival, and severe and persistent side effects of treatment are the outcomes that receive the highest priority on a group level when patients with cancer need to make trade-offs in oncologic treatment decisions