An anytime approximation method for the inverse Shapley value problem

Coalition formation is the process of bringing together two or more agents so as to achieve goals that individuals on their own cannot, or to achieve them more efficiently. Typically, in such situations, the agents have conflicting preferences over the set of possible joint goals. Thus, before the agents realize the benefits of cooperation, they must find a way of resolving these conflicts and reaching a consensus. In this context, cooperative game theory offers the voting game as a mechanism for agents to reach a consensus. It also offers the Shapley value as a way of measuring the influence or power a player has in determining the outcome of a voting game. Given this, the designer of a voting game wants to construct a game such that a players Shapley value is equal to some desired value. This is called the inverse Shapley value problem. Solving this problem is necessary, for instance, to ensure fairness in the players voting powers. However, from a computational perspective, finding a players Shapley value for a given game is #p-complete. Consequently, the problem of verifying that a voting game does indeed yield the required powers to the agents is also #P-complete. Therefore, in order to overcome this problem we present a computationally efficient approximation algorithm for solving the inverse problem. This method is based on the technique of successive approximations; it starts with some initial approximate solution and iteratively updates it such that after each iteration, the approximate gets closer to the required solution. This is an anytime algorithm and has time complexity polynomial in the number of players. We also analyze the performance of this method in terms of its approximation error and the rate of convergence of an initial solution to the required one. Specifically, we show that the former decreases after each iteration, and that the latter increases with the number of players and also with the initial approximation error. Copyright © 2008, International Foundation for Autonomous Agents and Multiagent Systems (www.ifaarnas.org). All rights reserved

On efficient procedures for multi-issue negotiation

This paper studies bilateral, multi-issue negotiation between self-interested agents with deadlines. There are a number of procedures for negotiating the issues and each of these gives a different outcome. Thus, a key problem is to decide which one to use. Given this, we study the three main alternatives: the package deal, the simultaneous procedure, and the sequential procedure. First, we determine equilibria for the case where each agent is uncertain about its opponent’s deadline. We then compare the outcomes for these procedures and determine the one that is optimal (in this case, the package deal is optimal for each party). We then compare the procedures in terms of their time complexity, the uniqueness and Pareto optimality of their solutions, and their time of agreement

Polyhexamethylene Biguanide and Nadifloxacin Self-Assembled Nanoparticles: Antimicrobial Effects against Intracellular Methicillin-Resistant Staphylococcus aureus

The treatment of skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge, partly due to localization of the bacteria inside the host’s cells, where antimicrobial penetration and efficacy is limited. We formulated the cationic polymer polyhexamethylene biguanide (PHMB) with the topical antibiotic nadifloxacin and tested the activities against intracellular MRSA in infected keratinocytes. The PHMB/nadifloxacin nanoparticles displayed a size of 291.3 ± 89.6 nm, polydispersity index of 0.35 ± 0.04, zeta potential of +20.2 ± 4.8 mV, and drug encapsulation efficiency of 58.25 ± 3.4%. The nanoparticles killed intracellular MRSA, and relative to free polymer or drugs used separately or together, the nanoparticles displayed reduced toxicity and improved host cell recovery. Together, these findings show that PHMB/nadifloxacin nanoparticles are effective against intracellular bacteria and could be further developed for the treatment of skin and soft tissue infections

Kinetically driven helix formation during the homopolymer collapse process

Using Langevin simulations, we find that simple 'generic' bead-and-spring homopolymer chains in a sufficiently bad solvent spontaneously develop helical order during the process of collapsing from an initially stretched conformation. The helix formation is initiated by the unstable modes of the straight chain, which drive the system towards a long-lived metastable transient state. The effect is most pronounced if hydrodynamic interactions are screened.Comment: 4 pages, 4 figure

Role of transvaginal sonography and hysteroscopy in abnormal uterine bleeding: does the diagnostic yield increase by combining transvaginal sonography, hysteroscopy and biopsy?

Background: Abnormal uterine bleeding is the most common complaint of perimenopausal and postmenopausal women. The aim of this study was 1) To evaluate the causes of abnormal uterine bleeding using transvaginal sonography, hysteroscopy and endometrial curettage to achieve the greatest diagnostic accuracy. 2) To determine the sensitivity and specificity of TVS and hysteroscopy in the detection of various uterine pathologies.Methods: This was a descriptive cross sectional study between January 2013 to June2014 in Sri Manakula Vinayagar medical college and hospital. After obtaining ethics committee approval, 100 consecutive patients with abnormal uterine bleeding between the age group of 35 and 55 years, who consented to participate in the study, were subjected to transvaginal sonography followed by diagnostic hysteroscopy combined with a directed biopsy. TVS and hysteroscopy was performed by two different investigators. The endometrial curettings and any intracavitary lesion were subjected to histopathological examination. Results tabulated and analysed using MS EXCEL and cross tabulation using Epi-info. Sensitivity, specificity, PPV, NPV for each pathology by TVS and hysteroscopy with HPE as the gold standard was calculated. Also the pathology causing abnormal uterine bleeding was computed by taking into account the endometrial characteristics and the associated lesions diagnosed by TVS, hysteroscopy and histopathological examination report.Results: 61 patients had only single lesions in the form of normal endometrium, atrophic endometrium, endometrial hyperplasia, endometrial polyp, malignancy and IU synechiae whereas 39 patients had lesions like intramural fibroids, adenomyosis, submucus myoma and polyps associated with different types of endometrium. The diagnostic accuracy of TVS and hysteroscopy were comparable for normal endometrium whereas hysteroscopy was found to be more accurate for endometrial polyps, endometrial hyperplasia and atrophic endometrium.Conclusions: The combination of transvaginal sonography, hysteroscopy and directed biopsy was found to increase the diagnostic yield in patients with abnormal uterine bleeding. As the diagnostic accuracy increased by combining the three modalities, an effective and appropriate management can be planned.

Evaluation of the resistance of few citrus rootstocks to alkalinity by applying a faste test of secreening

Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO(3)/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials

Knowledge, attitude and practices of pregnant women regarding anemia, iron rich diet and iron supplement

Background: Anemia in pregnancy has detrimental effects on maternal and child health and prevalence of anemia during pregnancy is alarmingly high, inspite of the implementation of  the national nutritional anemia prophylaxis programme which provides iron and folic acid which are the essential nutrients lacking in  their diet. The purpose of this study was to assess the knowledge, attitude and practices of pregnant women regarding anemia, Iron rich food and iron supplements and also to assess the impact of these factors and other socio demographic variables on the hemoglobin levels of these vulnerable groups of women.Methods: This is a cross sectional, descriptive institution based study conducted at Sri Manakula Vinayagar medical college hospital, Puducherry, India. Sample size was calculated using formula for single proportion with 5% marginal error and 95% CI and a non-response rate of 10% and was found to be 316. Data collection was carried out using a predesigned, self-administered questionnaire in local language in the antenatal clinic at the time of routine antenatal checkup, from pregnant women who consented to participate in the study. At the same sitting, 1 ml of blood was collected for hemoglobin estimation, analyzed and the result was recorded and disclosed to the patient. The data was entered in SPSS and analyzed using descriptive and inferential statistics (Chi square test).  A p value of <0.05 was considered to be statistically significant.Results: Assessment of knowledge revealed that only 39.87% of the participants were aware of and understood the term anemia. 53.8% of the participants accepted that pregnant women were more vulnerable to anemia and 66.1% responded correctly that the fetus will be affected by severe anemia. Only 32.6% gave the correct response that pregnant women should take iron supplementation in spite of taking a healthy diet. Only 44.62% of the participants were aware of their hemoglobin level in the current pregnancy. Knowledge about food rich in iron was poor among the participants. At least 1/5th of the participants have not received educational information regarding anemia from     any source. The overall attitude towards antenatal checkup, healthy diet and the benefits of iron supplementation was generally good among the participants 49.36% of the participants were taking only the usual diet during their pregnancy. 74.36% claimed to have taken iron supplementation regularly whereas 9.8% had not taken iron supplementation. On hemoglobin estimation it was found that 62.97% of the participants were anemic taking 11 grams as the cut off for anemia.  The only significant determinants of hemoglobin levels were regular intake of iron supplements   (p value   0.006) and timing of iron consumption (p value 0.0262).Conclusions: The present study indicated the lack of knowledge regarding anemia, iron rich foods and the importance of iron supplementation during pregnancy. Targeted estimation of hemoglobin levels in adolescent girls and women in reproductive age group, intensive counseling and motivation of pregnant women to consume Iron and folic acid and ensuring adequate supply to them, intensive de-worming, provision of toilet facilities to all households would help in reducing the incidence of anemia in pregnant women

Uterovaginal prolapse with myiasis: a case report

Myiasis is the infestation of the tissues of vertebrate animals by the larvae of flies. Genital myiasis is a rare condition, as it commonly presents as mucocutaneous form. We present a case of 80 year old lady with third degree uterovaginal prolapse and maggot infestation of an ulcer over the posterior aspect of the prolapse

Highlights of the 2nd Bioinformatics Student Symposium by ISCB RSG-UK [version 1]

Following the success of the 1 (st) Student Symposium by ISCB RSG-UK, a 2 (nd) Student Symposium took place on 7 (th) October 2015 at The Genome Analysis Centre, Norwich, UK. This short report summarizes the main highlights from the 2 (nd) Bioinformatics Student Symposium