Greedy Selfish Network Creation

We introduce and analyze greedy equilibria (GE) for the well-known model of selfish network creation by Fabrikant et al.[PODC'03]. GE are interesting for two reasons: (1) they model outcomes found by agents which prefer smooth adaptations over radical strategy-changes, (2) GE are outcomes found by agents which do not have enough computational resources to play optimally. In the model of Fabrikant et al. agents correspond to Internet Service Providers which buy network links to improve their quality of network usage. It is known that computing a best response in this model is NP-hard. Hence, poly-time agents are likely not to play optimally. But how good are networks created by such agents? We answer this question for very simple agents. Quite surprisingly, naive greedy play suffices to create remarkably stable networks. Specifically, we show that in the SUM version, where agents attempt to minimize their average distance to all other agents, GE capture Nash equilibria (NE) on trees and that any GE is in 3-approximate NE on general networks. For the latter we also provide a lower bound of 3/2 on the approximation ratio. For the MAX version, where agents attempt to minimize their maximum distance, we show that any GE-star is in 2-approximate NE and any GE-tree having larger diameter is in 6/5-approximate NE. Both bounds are tight. We contrast these positive results by providing a linear lower bound on the approximation ratio for the MAX version on general networks in GE. This result implies a locality gap of $\Omega(n)$ for the metric min-max facility location problem, where n is the number of clients.Comment: 28 pages, 8 figures. An extended abstract of this work was accepted at WINE'1

Locating Depots for Capacitated Vehicle Routing

We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost functions for the MST and k-median parts. We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the uniform case. Nevertheless, we obtain a constant-factor approximation algorithm, using an LP based approach.Comment: 12 pages, 1 figur

Are traditional marketing channels of kinnow really bad?

846-860Kinnow is being widely cultivated in North-Western part of India comprising the states of Punjab, Haryana and Rajasthan. The analysis of 180 kinnow farmers of three districts of North Western India namely Fazilka and Bathinda districts of Punjab and Sirsa district of Haryana revealed the existence of several marketing channels for marketing of kinnow having varied efficiency levels. Contrary to the believe, the traditional marketing channels (TMC) offered 15 to 19% higher net benefit under the situation of price and yield risk associated with the farms. The efficiency of farms associated with strong value chain finance (TMC) is higher as compared to farms associated with the weak value chain finance comprising the emerging marketing channels (EMC). These facts explain the continued faith of farms in the TMC as revealed by the proportion of farms supplying their produce through different market channels. The study advocates the need for evolution of newer forms of marketing channels and also co-existence of all as each has its own merits and demerits. The study offers suggestions for strengthening of kinnow value chain so that all the stakeholders are benefited. The collectivization of farmers in the form of farmer producer organization, availability of technology from various governmental and non-governmental institutions, the effective implementation of e-marketing app, evolution of crop insurance scheme and price stabilization fund for risk reduction are strategies to improve the kinnow value chain

Are traditional marketing channels of kinnow really bad?

Kinnow is being widely cultivated in North-Western part of India comprising the states of Punjab, Haryana and Rajasthan. The analysis of 180 kinnow farmers of three districts of North Western India namely Fazilka and Bathinda districts of Punjab and Sirsa district of Haryana revealed the existence of several marketing channels for marketing of kinnow having varied efficiency levels. Contrary to the believe, the traditional marketing channels (TMC) offered 15 to 19% higher net benefit under the situation of price and yield risk associated with the farms. The efficiency of farms associated with strong value chain finance (TMC) is higher as compared to farms associated with the weak value chain finance comprising the emerging marketing channels (EMC). These facts explain the continued faith of farms in the TMC as revealed by the proportion of farms supplying their produce through different market channels. The study advocates the need for evolution of newer forms of marketing channels and also co-existence of all as each has its own merits and demerits. The study offers suggestions for strengthening of kinnow value chain so that all the stakeholders are benefited. The collectivization of farmers in the form of farmer producer organization, availability of technology from various governmental and non-governmental institutions, the effective implementation of e-marketing app, evolution of crop insurance scheme and price stabilization fund for risk reduction are strategies to improve the kinnow value chain

How and When Socially Entrepreneurial Nonprofit Organizations Benefit From Adopting Social Alliance Management Routines to Manage Social Alliances?

Social alliance is defined as the collaboration between for-profit and nonprofit organizations. Building on the insights derived from the resource-based theory, we develop a conceptual framework to explain how socially entrepreneurial nonprofit organizations (SENPOs) can improve their social alliance performance by adopting strategic alliance management routines. We test our framework using the data collected from 203 UK-based SENPOs in the context of cause-related marketing campaign-derived social alliances. Our results confirm a positive relationship between social alliance management routines and social alliance performance. We also find that relational mechanisms, such as mutual trust, relational embeddedness, and relational commitment, mediate the relationship between social alliance management routines and social alliance performance. Moreover, our findings suggest that different types of social alliance motivation can influence the impact of social alliance management routines on different types of the relational mechanisms. In general, we demonstrate that SENPOs can benefit from adopting social alliance management routines and, in addition, highlight how and when the social alliance management routines–social alliance performance relationship might be shaped. Our study offers important academic and managerial implications, and points out future research directions

Prostate cancer tumour features on template prostate-mapping biopsies: implications for focal therapy.

Focal therapy is being offered as a viable alternative for men with localised prostate cancer (PCa), but it is unclear which men may be suitable

Prostate cancer tumour features on template prostate-mapping biopsies: implications for focal therapy.

Focal therapy is being offered as a viable alternative for men with localised prostate cancer (PCa), but it is unclear which men may be suitable

Effective practices of international volunteering for health : perspectives from partner organizations

Abstract: The demand for international volunteer experiences to promote global health and nutrition is increasing and numerous studies have documented the experiences of the international volunteers who travel abroad; however, little is known about effective practices from the perspective of partner organizations. This study aims to understand how variables such as the skill-level of volunteers, the duration of service, cultural and language training, and other key variables affect partner organizations’ perceptions of volunteer effectiveness at promoting healthcare and nutrition..