Correlation Clustering Based Coalition Formation For Multi-Robot Task Allocation

In this paper, we study the multi-robot task allocation problem where a group of robots needs to be allocated to a set of tasks so that the tasks can be finished optimally. One task may need more than one robot to finish it. Therefore the robots need to form coalitions to complete these tasks. Multi-robot coalition formation for task allocation is a well-known NP-hard problem. To solve this problem, we use a linear-programming based graph partitioning approach along with a region growing strategy which allocates (near) optimal robot coalitions to tasks in a negligible amount of time. Our proposed algorithm is fast (only taking 230 secs. for 100 robots and 10 tasks) and it also finds a near-optimal solution (up to 97.66% of the optimal). We have empirically demonstrated that the proposed approach in this paper always finds a solution which is closer (up to 9.1 times) to the optimal solution than a theoretical worst-case bound proved in an earlier work

Matchings with externalities and attitudes

Two-sided matchings are an important theoretical tool used to model markets and social interactions. In many real-life problems the utility of an agent is influenced not only by their own choices, but also by the choices that other agents make. Such an influence is called an externality. Whereas fully expressive representations of externalities in matchings require exponential space, in this paper we propose a compact model of externalities, in which the influence of a match on each agent is computed additively. Under this framework, we analyze many-to-many matchings and one-to-one matchings where agents take different attitudes when reasoning about the actions of others. In particular, we study optimistic, neutral and pessimistic attitudes and provide both computational hardness results and polynomial-time algorithms for computing stable outcomes

Neutralizing antibody response during acute and chronic hepatitis C virus infection

Little is known about the role of Abs in determining the outcome of hepatitis C virus (HCV) infection. By using infectious retroviral pseudotypes bearing HCV glycoproteins, we measured neutralizing Ab (nAb) responses during acute and chronic HCV infection. In seven acutely infected health care workers, only two developed a nAb response that failed to associate with viral clearance. In contrast, the majority of chronically infected patients had nAbs. To determine the kinetics of strain-specific and crossreactive nAb emergence, we studied patient H, the source of the prototype genotype 1a H77 HCV strain. An early weak nAb response, specific for the autologous virus, was detected at seroconversion. However, neutralization of heterologous viruses was detected only between 33 and 111 weeks of infection. We also examined the development of nAbs in 10 chimpanzees infected with H77 clonal virus. No nAb responses were detected in three animals that cleared virus, whereas strain-specific nAbs were detected in six of the seven chronically infected animals after approximately 50 weeks of infection. The delayed appearance of high titer crossreactive nAbs in chronically infected patients suggests that selective mechanism(s) may operate to prevent the appearance of these Abs during acute infection. The long-term persistence of these nAbs in chronically infected patients may regulate viral replication

The new paradigm of hepatitis C therapy: integration of oral therapies into best practices.

Emerging data indicate that all-oral antiviral treatments for chronic hepatitis C virus (HCV) will become a reality in the near future. In replacing interferon-based therapies, all-oral regimens are expected to be more tolerable, more effective, shorter in duration and simpler to administer. Coinciding with new treatment options are novel methodologies for disease screening and staging, which create the possibility of more timely care and treatment. Assessments of histologic damage typically are performed using liver biopsy, yet noninvasive assessments of histologic damage have become the norm in some European countries and are becoming more widespread in the United States. Also in place are new Centers for Disease Control and Prevention (CDC) initiatives to simplify testing, improve provider and patient awareness and expand recommendations for HCV screening beyond risk-based strategies. Issued in 2012, the CDC recommendations aim to increase HCV testing among those with the greatest HCV burden in the United States by recommending one-time testing for all persons born during 1945-1965. In 2013, the United States Preventive Services Task Force adopted similar recommendations for risk-based and birth-cohort-based testing. Taken together, the developments in screening, diagnosis and treatment will likely increase demand for therapy and stimulate a shift in delivery of care related to chronic HCV, with increased involvement of primary care and infectious disease specialists. Yet even in this new era of therapy, barriers to curing patients of HCV will exist. Overcoming such barriers will require novel, integrative strategies and investment of resources at local, regional and national levels

Association between proton pump inhibitor therapy and clostridium difficile infection: a contemporary systematic review and meta-analysis.

Abstract Introduction Emerging epidemiological evidence suggests that proton pump inhibitor (PPI) acid-suppression therapy is associated with an increased risk of Clostridium difficile infection (CDI). Methods Ovid MEDLINE, EMBASE, ISI Web of Science, and Scopus were searched from 1990 to January 2012 for analytical studies that reported an adjusted effect estimate of the association between PPI use and CDI. We performed random-effect meta-analyses. We used the GRADE framework to interpret the findings. Results We identified 47 eligible citations (37 case-control and 14 cohort studies) with corresponding 51 effect estimates. The pooled OR was 1.65, 95% CI (1.47, 1.85), I2 = 89.9%, with evidence of publication bias suggested by a contour funnel plot. A novel regression based method was used to adjust for publication bias and resulted in an adjusted pooled OR of 1.51 (95% CI, 1.26–1.83). In a speculative analysis that assumes that this association is based on causality, and based on published baseline CDI incidence, the risk of CDI would be very low in the general population taking PPIs with an estimated NNH of 3925 at 1 year. Conclusions In this rigorously conducted systemic review and meta-analysis, we found very low quality evidence (GRADE class) for an association between PPI use and CDI that does not support a cause-effect relationship

Machinability of natural fibre reinforced polymeric composites

From an industrial perspective, there are some issues with the machinability of synthetic fibre/polymer composites (glass fibres), including hole accuracy, delamination, appearance and energy consumption. These are mainly due to the abrasive nature of the synthetic fibres. Introducing natural fibres as reinforcement to the polymeric composite may overcome some of these issues, as natural fibres have less abrasive effects compared to synthetic fibres. Moreover, natural fibres are becoming an attractive candidate to replace synthetic fibres for several applications. In the current study, epoxy composites based on date palm fibres were developed. The interfacial adhesion of the date palm fibres with the matrix is first evaluated for optimum fibre diameter and NaOH concentrations through a single fibre pull out test. With regards to machinability of the composite, drilling experiments were conducted on neat epoxy, glass/epoxy and date/epoxy composites. A new dynamometer was developed and fabricated locally. The influence of the cutting speed, feed rate and drill diameter on the machinability of the composites was evaluated in terms of hole accuracy, inner and outer delamination, specific cutting pressure and machining power. Scanning electron microscopy and optical microscopy were used to examine the damaged features in the experiments of interfacial adhesion and machinability. The ANOVA approach was used to identify the most effective parameters on the machinability of the composites. The results revealed that NaOH concentration in the treatment solution affects the strength and the interfacial adhesion of the fibre with the matrix. Six per cent NaOH concentration is the optimum concentration in which there was less damage to the strength of the fibre and enhancement to the interfacial adhesion of the fibre with the matrix. Tensile properties of the epoxy were found to be improved with the addition of either natural or synthetic fibres. However, glass fibres improved the tensile strength of the epoxy significantly compared to the date palm fibre, even though glass fibres suffered from detachment and a pull out mechanism during loading conditions. In the drilling process for all materials, there were three regions observed: inner, intermediate and outer. The thrust and torque behaviour with the drilling time was divided into these three regions. The peak values were observed in the intermediate regions in which the shears occurred at a higher level with the thrust force. The presence of glass fibres in the epoxy composites assisted in reducing crack propagation at the inlet regions; however, it highly deteriorated the outlet region, as detachments and a decomposition mechanism were observed. For neat epoxy, cracks and fractures were the main damage features noticed. Meanwhile, the presence of date palm fibre in the epoxy improved the machinability of the composites, as it required similar values of torque and thrust to that of neat epoxy, while glass fibres needed more power. Date palm fibres assisted in reducing cracks in the inner and outer regions of the hole of the composites, even though pull out and detachments were observed. Hole accuracy is highly controlled by the operating parameters, as an increase in the drilling speed and feed rate resulted in high error percentage of hole accuracy for all materials. The addition of date palm fibres had a lower error percentage to the hole accuracy compared to the glass fibres, and this was mainly due to the abrasive nature of the glass fibres. Micrographs show fragmentations and pull out of fibres for neat epoxy and glass/epoxy composites, respectively. Meanwhile, date/epoxy exhibited fragmentation at the edge of the holes, which was considered less damage compared to the glass/epoxy. The specific cutting pressure reduced significantly with an increase in the feed rate. However, there was no clear effect from the drilling speeds on the specific cutting pressure. The most influential parameter was the drill diameter, as there was a large increase in the specific cutting pressure with an increase of the drill diameter. Conversely, the drilling process for all materials resulted in high roughness values for the inner surface of the holes. The highest roughness for the inner surface was recorded when the glass/epoxy was drilled. Nevertheless, the addition of the date palm fibre also contributed to an increase of surface roughness of the composites. However, there was less of an increase in the roughness of the inner surface with the addition of date palm fibres to the composite compared to glass fibres. Machining power was influenced by the higher operating parameter values; however, for the intermediate and low range operating parameter values, there was not much difference in the machining power of all materials. Interestingly, the machining power for the date/epoxy composite was competitive when compared to the neat epoxy, which is a promising result for the use of date palm fibre from a machinability perspective

Articles of Faith: Freedom of Expression and Religious Freedom in Contemporary Multiculture

This article examines the relationship between freedom of religion and freedom of speech and expression within contemporary multicultural liberal democracies. These two fundamental human rights have increasingly been seen, in public and political discourse, in terms of tension if not outright opposition, a view reinforced by the Charlie Hebdo killings in January 2015. And yet in every human rights charter they are proximate to one another. This essay argues that this adjacency is not coincidental, that it has a history and that, in illuminating this history, it is possible to explore how the contemporary framing of these two rights as being in opposition has come about. Looking back to the framing of the First Amendment of the US Constitution, the essay offers an historical perspective that, in turn, facilitates a reappraisal and re-evaluation of these two liberties that is the necessary, albeit insufficient, predicate to the task of addressing the problematic of multicultural ‘crisis' in the contemporary liberal democracies of Western Europe, North America and Australasia, in which the presence of certain religious communities (Muslims, in particular) and the role of religion in public and political life more generally (and, conversely, of secularism) has assumed a central importance

Charge Transfer and Tunable Ambipolar Effect Induced by Assembly of Cu (II) Binuclear Complexes on Carbon Nanotube Field Effect Transistor Devices

International audienceAssembly of paramagnetic Cu2 complexes with a Schiff base scaffold possessing extended electron delocalization together with a quasi-planar structure onto carbon nanotubes induces a diameter-selective charge transfer from the complex to the nanotubes leading to an interestingly large and tunable ambipolar effect. We used complementary techniques such as electron paramagnetic resonance, absorption spectroscopy, and photoluminescence to ensure the success of the assembly process and the integrity of the complex in the nanohybrid. We carried out density functional theory type calculations to rationalize the experimental results,evidencing the selective enhanced interaction of the metal complexes with one type of nanotube