The Least-core and Nucleolus of Path Cooperative Games

Cooperative games provide an appropriate framework for fair and stable profit distribution in multiagent systems. In this paper, we study the algorithmic issues on path cooperative games that arise from the situations where some commodity flows through a network. In these games, a coalition of edges or vertices is successful if it enables a path from the source to the sink in the network, and lose otherwise. Based on dual theory of linear programming and the relationship with flow games, we provide the characterizations on the CS-core, least-core and nucleolus of path cooperative games. Furthermore, we show that the least-core and nucleolus are polynomially solvable for path cooperative games defined on both directed and undirected network

Superconductivity in Cu_xTiSe_2

Charge density waves (CDWs) are periodic modulations of the conduction electron density in solids. They are collective states that arise from intrinsic instabilities often present in low dimensional electronic systems. The layered dichalcogenides are the most well-studied examples, with TiSe_2 one of the first CDW-bearing materials known. The competition between CDW and superconducting collective electronic states at low temperatures has long been held and explored, and yet no chemical system has been previously reported where finely controlled chemical tuning allows this competition to be studied in detail. Here we report how, upon controlled intercalation of TiSe_2 with Cu to yield Cu_xTiSe_2, the CDW transition is continuously suppressed, and a new superconducting state emerges near x = 0.04, with a maximum T_c of 4.15 K found at x = 0.08. Cu_xTiSe_2 thus provides the first opportunity to study the CDW to Superconductivity transition in detail through an easily-controllable chemical parameter, and will provide new insights into the behavior of correlated electron systems.Comment: Accepted to Nature Physic

Veterans Affairs Health System and Mental Health Treatment Retention among Patients with Serious Mental Illness: Evaluating Accessibility and Availability Barriers

We examine the impact of two dimensions of access—geographic accessibility and availability—on VA health system and mental health treatment retention among patients with serious mental illness (SMI). Methods . Among 156,631 patients in the Veterans Affairs (VA) health care system with schizophrenia or bipolar disorder in fiscal year 1998 (FY98), we used Cox proportional hazards regression to model time to first 12-month gap in health system utilization, and in mental health services utilization, by the end of FY02. Geographic accessibility was operationalized as straight-line distance to nearest VA service site or VA psychiatric service site, respectively. Service availability was assessed using county-level VA hospital beds and non-VA beds per 1,000 county residents. Patients who died without a prior gap in care were censored. Results . There were 32, 943 patients (21 percent) with a 12-month gap in health system utilization; 65,386 (42 percent) had a 12-month gap in mental health services utilization. Gaps in VA health system utilization were more likely if patients were younger, nonwhite, unmarried, homeless, nonservice-connected, if they had bipolar disorder, less medical morbidity, an inpatient stay in FY98, or if they lived farther from care or in a county with fewer VA inpatient beds. Similar relationships were observed for mental health, however being older, female, and having greater morbidity were associated with increased risks of gaps, and number of VA beds was not significant. Conclusions . Geographic accessibility and resource availability measures were associated with long-term continuity of care among patients with SMI. Increased distance from providers was associated with greater risks of 12-month gaps in health system and mental health services utilization. Lower VA inpatient bed availability was associated with increased risks of gaps in health system utilization. Study findings may inform efforts to improve treatment retention.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73433/1/j.1475-6773.2006.00642.x.pd

No exit from the euro-rescuing trap?

This paper attempts a normative assessment of the input and output-oriented legitimacy of the present euro-rescuing regime on the basis of policy analyses examining the causes of present crises, the available policy options, and the impact of the policies actually chosen. Concluding that the regime lacks input-oriented legitimacy and that its claim to output-oriented legitimacy is ambivalent at best, the paper explores potential – majoritarian or unilateral – exits from the present institutional constellation that is characterized by the synthesis of a non-democratic expertocracy and an extremely asymmetric intergovernmental bargaining system.Die hier präsentierte normative Bewertung der input- und outputorientierten Legitimität des gegenwärtigen Euro-Rettungs-Regimes stützt sich auf empirisch fundierte Aussagen zu den Ursachen der Eurokrise, den prinzipiell verfügbaren Politik-Optionen und den Wirkungen der gewählten Politik. Im Ergebnis wird eine inputorientierte Legitimation verneint, während die outputorientierte Bewertung höchst ambivalent erscheint. Im Schlussteil untersucht der Text mögliche – majoritäre oder einseitige – Auswege aus einer institutionellen Konstellation, die ein nicht demokratisches Expertenregime mit inem extrem asymmetrischen intergouvernementalen Verhandlungsregime verbindet

ARPES: A probe of electronic correlations

Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct methods of studying the electronic structure of solids. By measuring the kinetic energy and angular distribution of the electrons photoemitted from a sample illuminated with sufficiently high-energy radiation, one can gain information on both the energy and momentum of the electrons propagating inside a material. This is of vital importance in elucidating the connection between electronic, magnetic, and chemical structure of solids, in particular for those complex systems which cannot be appropriately described within the independent-particle picture. Among the various classes of complex systems, of great interest are the transition metal oxides, which have been at the center stage in condensed matter physics for the last four decades. Following a general introduction to the topic, we will lay the theoretical basis needed to understand the pivotal role of ARPES in the study of such systems. After a brief overview on the state-of-the-art capabilities of the technique, we will review some of the most interesting and relevant case studies of the novel physics revealed by ARPES in 3d-, 4d- and 5d-based oxides.Comment: Chapter to appear in "Strongly Correlated Systems: Experimental Techniques", edited by A. Avella and F. Mancini, Springer Series in Solid-State Sciences (2013). A high-resolution version can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Reviews/ARPES_Springer.pdf. arXiv admin note: text overlap with arXiv:cond-mat/0307085, arXiv:cond-mat/020850

Role of seminal plasma in the anti-HIV-1 activity of candidate microbicides

BACKGROUND: Evaluation of microbicides for prevention of HIV-1 infection in macaque models for vaginal infection has indicated that the concentrations of active compounds needed for protection by far exceed levels sufficient for complete inhibition of infection in vitro. These experiments were done in the absence of seminal plasma (SP), a vehicle for sexual transmission of the virus. To gain insight into the possible effect of SP on the performance of selected microbicides, their anti-HIV-1 activity in the presence, and absence of SP, was determined. METHODS: The inhibitory activity of compounds against the X4 virus, HIV-1 IIIB, and the R5 virus, HIV-1 BaL was determined using TZM-bl indicator cells and quantitated by measuring β-galactosidase induced by infection. The virucidal properties of cellulose acetate 1,2-benzene-dicarboxylate (CAP), the only microbicide provided in water insoluble, micronized form, in the presence of SP was measured. RESULTS: The HIV-1 inhibitory activity of the polymeric microbicides, poly(naphthalene sulfonate), cellulose sulfate, carrageenan, CAP (in soluble form) and polystyrene sulfonate, respectively, was considerably (range ≈ 4 to ≈ 73-fold) diminished in the presence of SP (33.3%). Formulations of micronized CAP, providing an acidic buffering system even in the presence of an SP volume excess, effectively inactivated HIV-1 infectivity. CONCLUSION: The data presented here suggest that the in vivo efficacy of polymeric microbicides, acting as HIV-1 entry inhibitors, might become at least partly compromised by the inevitable presence of SP. These possible disadvantages could be overcome by combining the respective polymers with acidic pH buffering systems (built-in for formulations of micronized CAP) or with other anti-HIV-1 compounds, the activity of which is not affected by SP, e.g. reverse transcriptase and zinc finger inhibitors

Estimation, planning, and mapping for autonomous flight using an RGB-D camera in GPS-denied environments

RGB-D cameras provide both color images and per-pixel depth estimates. The richness of this data and the recent development of low-cost sensors have combined to present an attractive opportunity for mobile robotics research. In this paper, we describe a system for visual odometry and mapping using an RGB-D camera, and its application to autonomous flight. By leveraging results from recent state-of-the-art algorithms and hardware, our system enables 3D flight in cluttered environments using only onboard sensor data. All computation and sensing required for local position control are performed onboard the vehicle, reducing the dependence on an unreliable wireless link to a ground station. However, even with accurate 3D sensing and position estimation, some parts of the environment have more perceptual structure than others, leading to state estimates that vary in accuracy across the environment. If the vehicle plans a path without regard to how well it can localize itself along that path, it runs the risk of becoming lost or worse. We show how the belief roadmap algorithm prentice2009belief, a belief space extension of the probabilistic roadmap algorithm, can be used to plan vehicle trajectories that incorporate the sensing model of the RGB-D camera. We evaluate the effectiveness of our system for controlling a quadrotor micro air vehicle, demonstrate its use for constructing detailed 3D maps of an indoor environment, and discuss its limitations.United States. Office of Naval Research (Grant MURI N00014-07-1-0749)United States. Office of Naval Research (Science of Autonomy Program N00014-09-1-0641)United States. Army Research Office (MAST CTA)United States. Office of Naval Research. Multidisciplinary University Research Initiative (Grant N00014-09-1-1052)National Science Foundation (U.S.) (Contract IIS-0812671)United States. Army Research Office (Robotics Consortium Agreement W911NF-10-2-0016)National Science Foundation (U.S.). Division of Information, Robotics, and Intelligent Systems (Grant 0546467

Do bone mineral content and density determine fracture in children? A possible threshold for physical activity

BackgroundRelations between bone parameters, physical exertion, and childhood fractures are complex. We aimed to estimate the associations between fracture history and bone mineral content (BMC) and areal bone mineral density (aBMD) at 7 years of age, by levels of physical activity, as a proxy for trauma frequency.MethodsWe used data collected from 2,261 children of the Generation XXI birth cohort, assembled in 2005/6 in Porto, Portugal. At the age of 7 years (2012/4), fracture history, time spent per week in active play, and sports practice were reported by parents. Subtotal and lumbar spine (LS) BMC and aBMD were measured using whole-body dual-energy X-ray absorptiometry.ResultsBoys and girls in the highest categories of time spent in sports practice or active play generally had higher BMC and aBMD. Among girls, BMC and aBMD were protective of fracture only in the highest quarter of active play (>660 min/week)-odds ratios (OR; 95% confidence interval (95% CI)) for subtotal BMC=0.27 (0.11-0.67), subtotal aBMD=0.18 (0.06-0.49), and LS aBMD=0.41 (0.22-0.75). For boys in the highest quarter of sports practice (>240 min/week), subtotal and LS BMC were protective of fracture-OR=0.39 (0.16-0.98) and 0.51 (0.27-0.96), respectively.ConclusionIn prepubertal children, BMC and aBMD predicted fracture history only in the highest levels of physical activity.info:eu-repo/semantics/publishedVersio