748 research outputs found
The weight of institutions on women's capabilities
The objective of this paper is to assess the links between institutions and quality of life, within Nussbaum's capability framework approach, exploring a relevant empirical issue: microfinance. Microfinance appears more and more as a tool for women's empowerment. Available results of impact studies call for circumspection; microfinance can free women from certain links of dependence. But microfinance can also forge new kinds of dependence and subordination, thereby strengthening the disparities between men and women, but also among women themselves.microfinance, capabilities, institutions, Martha Nussbaum, Amartya Sen, women, empowerment
Towards a Practical and Fair Rate Allocation for Multihop Wireless Networks based on a Simple Node Model
IEEE 802.11 is often considered as the underlying wireless technology of multihop wireless networks. But the use of 802.11 in such networks raises issues, like efficiency and/or fairness issues. Different kinds of solutions have been proposed to overcome these problems. One approach is to design new MAC protocols that provide alternatives to the IEEE 802.11 MAC protocol. Although these solutions are of some interest, it should probably take some time before new wireless network interface cards based on one of these solutions are developed and released. Another approach is to consider that 802.11 will remain the underlying wireless technology and to design solutions above it. Several solutions based on rate allocation have been proposed so far. The main drawback of the proposed solutions is that they rely on a radio medium sharing model that is difficult to compute in a wireless, distributed and mobile environment. Indeed, very few of these solutions have been derived into a network protocol. In this article, we propose a distributed and dynamic rate allocation solution that is based on a simple sharing model. Due to its simplicity, we can derive a network protocol that can be practically used in multihop wireless networks. This protocol provides a fair bandwidth sharing between end-to-end flows while maintaining an efficient overall throughput in the network. This solution has been implemented in NS2 and evaluated by simulations
BRuIT : Bandwidth Reservation under Interferences Influence
This paper deals with the bandwidth reservation problem in ad hoc networks and with the influence that interferences between signals have on this problem. We show that interferences could decrease the applications rates. This can be a real problem for applications that need guarantees. We propose a distributed protocol (called BRuIT) for bandwidth reservation in ad hoc networks that takes into account the existence of interferences from far transmissions. The protocol is analyzed through simulations carried out under NS: we evaluate the signaling overhead required for maintaining the knowledge of existing interferences ; we show that this knowledge reduces delays in case of congestion ; we measure the time for rebuilding broken routes ; and finally we show that this protocol maintains the rate of accepted applications.Cet article traite du problème de réservation de bande passante dans les réseaux ad-hoc et de l’influence des interférences hertziennes sur ce problème. Nous montrons que le phénomène d’interférences peut être à l’origine de pertes de bande passante qui peuvent être problématique pour les applications nécessitant des garanties. nous proposons un protocole distribué de réservation de bande passante pour réseaux ad-hoc appelé BRuIT. Ce protocole prend en compte l’existence d’interférences entre transmissions lointaines. Les performances de BRuIT sont analysées au moyen de simulations sous NS
Generating Random Permutations in the Framework of Parallel Coarse Grained Models
We present three algorithms for generating random permutations in the coarse grained model CGM. For each of the proposed algorithms, we study the number of supersteps, the size of the local memory, the overall communicat- ion cost and we check if it gives a permutation with the uniform distribution or not. The proposed algorithms are intended to be simple and of practical relevance. The difficulty, in this paper, lies in proving that they are the desired properties
SBA : un algorithme simple de backoff pour les réseaux ad hoc
National audienceLes performances d'un réseau ad hoc utilisant 802.11 se dégradent quand la charge du réseau augmente. Cette surcharge du réseau peut provenir de sa densité ou du trafic généré. La perte de performance vient essentiellement du protocole MAC (Medium Access Control) mis en place dans le mode DCF du standard 802.11. On trouve dans la littérature plusieurs solutions au niveau MAC permettant de maintenir les performances telles que l'équité ou l'efficacité mais peu de ces solutions n'abordent le problème de l'équité et de l'efficacité conjointement. Dans cet article nous proposons un algorithme de backoff, SBA (Simple Backoff Algorithm), permettant d'obtenir un bon compromis équité-efficacité quand le réseau est surchargé. De plus, notre algorithme est simple car il ne s'appuie que sur des informations locales. L'analyse et les simulations montrent que SBA permet d'obtenir un meilleur compromis entre équité, efficacité et simplicité comparé à certains protocoles décrits dans la littérature
SBA: A Simple Backoff Algorithm for Wireless Ad Hoc Networks
International audienceThe performance of ad hoc networks based on IEEE 802.11 DCF degrade when congestion increases. The issues concern efficiency and fairness. Many solutions can be found at the MAC layer in the literature, but very few solutions improve fairness and efficiency at the same time. In this paper, we design a new backoff solution, called SBA. SBA uses only local information and two contention window sizes. By simulations, we compare SBA with IEEE 802.11 and several alternatives to 802.11 in ad hoc networks. We show that SBA achieves a good trade-off between fairness, simplicity and efficiency
Estimating Average End-to-End Delays in IEEE 802.11 Multihop Wireless Networks
In this paper, we present a new analytic model for evaluating average end-to-end delay in IEEE 802.11 multihop wireless networks. Our model gives closed expressions for the end-to-end delay in function of arrivals and service time patterns. Each node is modeled as a M/M/1/K queue from which we can derive expressions for service time via queueing theory. By combining this delay evaluation with different admission controls, we design a protocol called DEAN (Delay Estimation in Ad hoc Networks). DEAN is able to provide delay guarantees for QoS applications in function of the application level requirements. Through extensive simulations, we compare performance evaluation of DEAN with other approaches like, for instance, DDA
L'étalon-or des évaluations randomisées : du discours de la méthode à l'économie politique
La dernière dĂ©cennie a vu l'Ă©mergence d'un nouveau champ de recherche en Ă©conomie du dĂ©veloppement : les mĂ©thodes expĂ©rimentales d'Ă©valuation d'impacts par assignation alĂ©atoire. Cet article explore le contraste entre d’une part les limites (nombreuses) et la circonscription (très Ă©troite) du champ rĂ©el d'application de ces mĂ©thodes et d’autre part leur succès, attestĂ© Ă la fois par leur nombre et leur forte mĂ©diatisation. L’analyse suggère que ce contraste est le fruit d’une conjonction Ă©conomique et politique particulière, Ă©manant de stratĂ©gies novatrices de la part des chercheurs de cette nouvelle Ă©cole, et d’intĂ©rĂŞts et de prĂ©fĂ©rences spĂ©cifiques provenant Ă la fois du monde acadĂ©mique et de la communautĂ© des donateurs
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