1,900 research outputs found

    Yang-Lee Edge Singularity on a Class of Treelike Lattices

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    The density of zeros of the partition function of the Ising model on a class of treelike lattices is studied. An exact closed-form expression for the pertinent critical exponents is derived by using a couple of recursion relations which have a singular behavior near the Yang-Lee edge.Comment: 9 pages AmsTex, 2 eps figures, to appear in J.Phys.

    Continuously-variable survival exponent for random walks with movable partial reflectors

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    We study a one-dimensional lattice random walk with an absorbing boundary at the origin and a movable partial reflector. On encountering the reflector, at site x, the walker is reflected (with probability r) to x-1 and the reflector is simultaneously pushed to x+1. Iteration of the transition matrix, and asymptotic analysis of the probability generating function show that the critical exponent delta governing the survival probability varies continuously between 1/2 and 1 as r varies between 0 and 1. Our study suggests a mechanism for nonuniversal kinetic critical behavior, observed in models with an infinite number of absorbing configurations.Comment: 5 pages, 3 figure

    Anomalous f-electron Hall Effect in the Heavy-Fermion System CeTIn5_{5} (T = Co, Ir, or Rh)

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    The in-plane Hall coefficient RH(T)R_{H}(T) of CeRhIn5_{5}, CeIrIn5_{5}, and CeCoIn5_{5} and their respective non-magnetic lanthanum analogs are reported in fields to 90 kOe and at temperatures from 2 K to 325 K. RH(T)R_{H}(T) is negative, field-independent, and dominated by skew-scattering above \sim 50 K in the Ce compounds. RH(H0)R_{H}(H \to 0) becomes increasingly negative below 50 K and varies with temperature in a manner that is inconsistent with skew scattering. Field-dependent measurements show that the low-T anomaly is strongly suppressed when the applied field is increased to 90 kOe. Measurements on LaRhIn5_{5}, LaIrIn5_{5}, and LaCoIn5_{5} indicate that the same anomalous temperature dependence is present in the Hall coefficient of these non-magnetic analogs, albeit with a reduced amplitude and no field dependence. Hall angle (θH\theta_{H}) measurements find that the ratio ρxx/ρxy=cot(θH)\rho_{xx}/\rho_{xy}=\cot(\theta_{H}) varies as T2T^{2} below 20 K for all three Ce-115 compounds. The Hall angle of the La-115 compounds follow this T-dependence as well. These data suggest that the electronic-structure contribution dominates the Hall effect in the 115 compounds, with ff-electron and Kondo interactions acting to magnify the influence of the underlying complex band structure. This is in stark contrast to the situation in most 4f4f and 5f5f heavy-fermion compounds where the normal carrier contribution to the Hall effect provides only a small, T-independent background to RH.R_{H}.Comment: 23 pages and 8 figure

    Hemodynamic impact of isobaric levobupivacaine versus hyperbaric bupivacaine for subarachnoid anesthesia in patients aged 65 and older undergoing hip surgery

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    BackgroundThe altered hemodynamics, and therefore the arterial hypotension is the most prevalent adverse effect after subarachnoid anesthesia. The objective of the study was to determine the exact role of local anesthetic selection underlying spinal anesthesia-induced hypotension in the elderly patient. We conducted a descriptive, observational pilot study to assess the hemodynamic impact of subarachnoid anesthesia with isobaric levobupivacaine versus hyperbaric bupivacaine for hip fracture surgery.DescriptionHundred twenty ASA status I-IV patients aged 65 and older undergoing hip fracture surgery were enrolled. The primary objective of our study was to compare hemodynamic effects based on systolic blood pressure (SBP) and dyastolic blood pressure (DBP) values, heart rate (HR) and hemoglobin (Hb) and respiratory effects based on partial oxygen saturation (SpO2%) values. The secondary objective was to assess potential adverse events with the use of levobupivacaine versus bupivacaine. Assessments were performed preoperatively, at 30 minutes into surgery, at the end of anesthesia and at 48 hours and 6 months after surgery.Among intraoperative events, the incidence of hypotension was statistically significantly higher (p <0.05) in group BUPI (38.3%) compared to group LEVO (13.3%). There was a decrease (p <0.05) in systolic blood pressure (SBP) and diastolic blood pressure (DBP) at 30 minutes intraoperatively (19% in group BUPI versus 17% in group LEVO). SpO2% increased at 30 minutes after anesthesia onset (1% in group BUPI versus 1.5% in group LEVO). Heart rate (HR) decreased at 30 minutes after anesthesia onset (5% in group BUPI versus 9% in group L). Hemoglobin (Hb) decreased from time of operating room (OR) admission to the end of anesthesia (9.3% in group BUPI versus 12.5% in group LEVO). The incidence of red blood cell (RBC) transfusion was 13.3% in group BUPI versus 31.7% in group LEVO, this difference was statistically significant. Among postoperative events, the incidence of congestive heart failure (CHF) was significantly higher in group BUPI (8,3%). At 6 months after anesthesia, no differences were found.ConclusionsGiven the hemodynamic stability and lower incidence of intraoperative hypotension observed, levobupivacaine could be the agent of choice for subarachnoid anesthesia in elderly patients

    Efficient Experimental and Data-Centered Workflow for Microstructure-Based Fatigue Data – Towards a Data Basis for Predictive AI Models

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    Background Early fatigue mechanisms for various materials are yet to be unveiled for the (very) high-cycle fatigue (VHCF) regime. This can be ascribed to a lack of available data capturing initial fatigue damage evolution, which continues to adversely affect data scientists and computational modeling experts attempting to derive microstructural dependencies from small sample size data and incomplete feature representations. Objective The aim of this work is to address this lack and to drive the digital transformation of materials such that future virtual component design can be rendered more reliable and more efficient. Achieving this relies on fatigue models that comprehensively capture all relevant dependencies. Methods To this end, this work proposes a combined experimental and data post-processing workflow to establish multimodal fatigue crack initiation and propagation data sets efficiently. It evolves around fatigue testing of mesoscale specimens to increase damage detection sensitivity, data fusion through multimodal registration to address data heterogeneity, and image-based data-driven damage localization. Results A workflow with a high degree of automation is established, that links large distortion-corrected microstructure data with damage localization and evolution kinetics. The workflow enables cycling up to the VHCF regime in comparatively short time spans, while maintaining unprecedented time resolution of damage evolution. Resulting data sets capture the interaction of damage with microstructural features and hold the potential to unravel a mechanistic understanding. Conclusions The proposed workflow lays the foundation for future data mining and data-driven modeling of microstructural fatigue by providing statistically meaningful data sets extendable to a wide range of materials

    Participatory Imaging Mapping of Cultural Heritage Across Internal Borders Stolac, Bosnia and Herzegovina

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    During the war in Bosnia and Herzegovina (1992&ndash;1995) cultural heritage was explicitly targeted and the state of destruction was extensive to both sacral and secular monuments. Two decades after the end of hostilities the perception of the historic environment is still defined from the angles of national, religious or ethnic belonging. Enabling recognition, reconciliation, tolerance and respect within the community of Stolac, Bosnia & Herzegovina through a better understanding and sharing of cultural heritage was the focus of this project. Stolac is representative of the problems in the region and stands out for its particularly sharp divisions. Until recently there was segregation with local schools and their curriculum was divided with cultural heritage generally not addressed. How can this small community engage with heritage and develop a dialogue that encourages tolerance, respect and as a base for development? How does one understand, then document areas significance to the community? Finally, how can technology assist? The focus of this paper is to relate the experiences and findings of a project that incorporated participatory imaging mapping and the use of technology to bridge between the internal borders of this small community. It will outline a methodology, experiences of the participants and results from their exercises in order to assist other communities facing similar issues

    Exploiting the Enumeration of All Feature Model Configurations

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    .Feature models are widely used to encode the configurations of a software product line in terms of mandatory, optional and exclusive features as well as propositional constraints over the features. Numerous computationally expensive procedures have been developed to model check, test, configure, debug, or compute relevant information of feature models. In this paper we explore the possible improvement of relying on the enumeration of all configurations when performing automated analysis operations. We tackle the challenge of how to scale the existing enumeration techniques by relying on distributed computing. We show that the use of distributed computing techniques might offer practical solutions to previously unsolvable problems and opens new perspectives for the automated analysis of software product lines.Junta de Andalucía P12-TIC-1867Ministerio de Economía y Competitividad TIN2015- 70560-
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