Are neighbors welcome ? e-buyer search, price competition and coalition strategy in the Internet retailing

On étudie les forces qui régissent l'agrégation des sites Web marchands (B-to-C) en concurrence sur un marché électronique différencié, où le coût de recherche pour les consommateurs est indépendant du coût d'adaptation/transport supporté lorsque le bien trouvé ne correspond pas à leur préférence. On s'intéresse à la possibilité pour les sites Internet de se coaliser, ce qui se traduit par une réduction du coût de recherche pour trouver d'autres sites à l'intérieur de la coalition. On effectue la statique comparative des structures de coalitions (en fonction du degré de différenciation de ses partenaires) lorsque les sites se font une concurrence en prix. On montre qu'un site préfère se coaliser avec un partenaire fortement différencié et fixe dans ce cas un prix unique plus bas.En vendant au détail;Coûts de recherche;Coalition

Consumers' Search Cost and Emerging Structure of Web Sites Coalitions : a multi-agent based simulation of an electronic market

On développe un modèle multi-agent, extension d'un modèle analytique qui étudie la structure des coalitions de sites B-to-C, lorsque les consommateurs-internautes ont un coût de recherche pour trouver le bien qui correspond à leur préférence, et lorsque les coalitions de sites permettent de réduire ces coûts de recherche via des moteurs de recherche spécialisés. Ce modèle multi-agent comporte des agents hétérogènes à rationnalité limitée: sites et internautes, dont on défini l'état et les règles de comportement. Notre objectif est de faire des simultations qui mettent en jeu ces deux types d'agents (une populations de sites marchands et une population de consommateurs), de les faire intéragir à travers une procédure de recherche des consommateurs et un processus de formation des coalitions des sites, et d'observer la dynamique du système, en particulier en ce qui concerne la structure de coalition émergente. Le modèle multi-agent étends ainsi les résultats obtenus dans le modèle analytique, avec des hypothèses moins restrictives. En plus du processus de formation des coalitions, le modèle théorique se voit aussi enrichi par d'autres règles de comportement pour les sites (entrée sur le marché, faillite), ce qui apporte des enseignements sur la dynamique de la concurrence lorsque la formation des coalition permet d'accroître la demande au détriment des sites peu ou non coalisées.Commerce électronique;Multi-agents;formation de coalitions

Are neighbors welcome ? e-buyer search, price competition and coalition strategy in the Internet retailing

We study the forces that drive the phenomenon of aggregation of merchant Web sites (B-to-C) competing in a differentiated electronic market, where the search cost for the consumers is independent from the adaptation/transportation cost they incur when the good they find does not match with their preference. We focus on the possibility for Internet sites to coalesce, which results in a reduction of the search cost to find other sites within the coalition. We do the static comparative of coalition structures (depending on whether there is little or high differentiation between partners), when firms compete in price. We find that firms prefer to coalesce with highly differentiated partners, and set in this case lower prices.On étudie les forces qui régissent l'agrégation des sites Web marchands (B-to-C) en concurrence sur un marché électronique différencié, où le coût de recherche pour les consommateurs est indépendant du coût d'adaptation/transport supporté lorsque le bien trouvé ne correspond pas à leur préférence. On s'intéresse à la possibilité pour les sites Internet de se coaliser, ce qui se traduit par une réduction du coût de recherche pour trouver d'autres sites à l'intérieur de la coalition. On effectue la statique comparative des structures de coalitions (en fonction du degré de différenciation de ses partenaires) lorsque les sites se font une concurrence en prix. On montre qu'un site préfère se coaliser avec un partenaire fortement différencié et fixe dans ce cas un prix unique plus bas

Irreversibility and Uncertainty in Multifunctional Forest Management Allocation

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Consumers' Search Cost and Emerging Structure of Web Sites Coalitions : a multi-agent based simulation of an electronic market

We have developed an agent-based computational model, extension of an analytical model that studies the structure of coalitions of B-to-C web sites, when Internet buyers incur search costs for finding the good that matches their preferences, and coalitions of sites reduce this cost through specialized search engines. This multi-agent model consists of heterogeneous, bounded rational agents: sites and web users, which have states and rules of behavior. Our goal is to run simulations by instantiating two agent populations (a population of sites/sellers and a population of web users/consumers), let the agents interact through the consumer search process and the coalition formation process, and monitor the evolution of the simulations in order to study the emerging dynamics, in particular the emerging coalition structure. The agent-based model extends the analytical results for less restricting assumptions. Moreover, beyond the coalition formation process, the analytical model is enriched by additional behaviors for the sites (entry and death), which give insights on the dynamics of competition when building coalition matters for increasing demand at the expense of non or less coalesced sites.On développe un modèle multi-agent, extension d'un modèle analytique qui étudie la structure des coalitions de sites B-to-C, lorsque les consommateurs-internautes ont un coût de recherche pour trouver le bien qui correspond à leur préférence, et lorsque les coalitions de sites permettent de réduire ces coûts de recherche via des moteurs de recherche spécialisés. Ce modèle multi-agent comporte des agents hétérogènes à rationnalité limitée: sites et internautes, dont on défini l'état et les règles de comportement. Notre objectif est de faire des simultations qui mettent en jeu ces deux types d'agents (une populations de sites marchands et une population de consommateurs), de les faire intéragir à travers une procédure de recherche des consommateurs et un processus de formation des coalitions des sites, et d'observer la dynamique du système, en particulier en ce qui concerne la structure de coalition émergente. Le modèle multi-agent étends ainsi les résultats obtenus dans le modèle analytique, avec des hypothèses moins restrictives. En plus du processus de formation des coalitions, le modèle théorique se voit aussi enrichi par d'autres règles de comportement pour les sites (entrée sur le marché, faillite), ce qui apporte des enseignements sur la dynamique de la concurrence lorsque la formation des coalition permet d'accroître la demande au détriment des sites peu ou non coalisées

Pedagogical memory and the space of the postcolonial classroom : reading Dangarembga's Nervous Conditions

This article addresses issues of the mnemonic space of the literature classroom by interrogating a classic text of African women’s writing, Tsitsi Dangaremnga’s Nervous Conditions (1988) for the ways it speaks about education in 1960s and 1970s late-colonial Rhodesia. The article suggests that the novel reviews and critiques a number of memorial strategies that were crucial to the colonial educational system, thereby facilitating a reflexive application of the novel’s concerns to the contexts in which it is often taught, that of today’s postcolonial classrooms. The article seeks to place Dangarembga’s novel in the context of its present moment, contemporary South Africa – that of the present critic’s site of practice, both pedagogical and scholarly, and that of many of this article’s readers. This present moment, in turn, is made up the many sites, successive and simultaneous, in which the novel’s work of memory is being re-activated in the minds of students as readers and writers. Via a dialogue between the textual past and the pedagogical present, one which is often subject to critical amnesia, the article seeks to inaugurate a debate on the nature of pedagogical memory in the space of the postcolonial university or high school literature classroom.http://www.informaworld.com/RSCRhb2013gv201

Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats

In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Development’s (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Bilan économique du stockage en réserve qualitative de vin de Champagne

Une version préliminaire a été publiée dans : Cahier du LORIA ; 2003-08Dans le cadre des appellations d'origine, la régulation de l'offre effectuée par les groupements de producteurs est sensée pallier de trop fortes variations de qualité du vin dues aux aléas climatiques qui conditionnent le rendement et la qualité du raisin récolté. Néanmoins, ce type de régulation pourrait s'avérer préjudiciable à l'intérêt des consommateurs en raison de l'élévation des prix résultant du stockage. Un logiciel basé sur un algorithme de contrôle stochastique nous permet de quantifier les effets d'une telle politique sur le surplus du producteur et du consommateur