19,785 research outputs found

    Positional estimation techniques for an autonomous mobile robot

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    Techniques for positional estimation of a mobile robot navigation in an indoor environment are described. A comprehensive review of the various positional estimation techniques studied in the literature is first presented. The techniques are divided into four different types and each of them is discussed briefly. Two different kinds of environments are considered for positional estimation; mountainous natural terrain and an urban, man-made environment with polyhedral buildings. In both cases, the robot is assumed to be equipped with single visual camera that can be panned and tilted and also a 3-D description (world model) of the environment is given. Such a description could be obtained from a stereo pair of aerial images or from the architectural plans of the buildings. Techniques for positional estimation using the camera input and the world model are presented

    Event anisotropy in 4.2A GeV/c C+C collisions

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    The directed and elliptic flow of protons and negative pions in 4.2A GeV/c C+C collisions is studied using the Fourier analysis of azimuthal distributions. It is found that the protons exhibit pronounced directed flow, while the flow of pions is either non existent or too weak to be detected experimentally. Also, it is found that in the entire rapidity interval the elliptic flow is very small if not zero. These results are confirmed by the Quark-Gluon-String Model (QGSM) and the relativistic transport model (ART 1.0), except that these models predict very weak antiflow of pions. The more detailed comparison with the QGSM suggests that the decay of resonances and rescattering of secondaries dominantly determine the proton and negative pion flow at this energy.Comment: 7 pages, 3 figures, TeX file changed from double to single-spacin

    On fixed linear systems with a generalized performance criteria

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    Fixed linear systems with generalized performance criteri

    Extending local features with contextual information in graph kernels

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    Graph kernels are usually defined in terms of simpler kernels over local substructures of the original graphs. Different kernels consider different types of substructures. However, in some cases they have similar predictive performances, probably because the substructures can be interpreted as approximations of the subgraphs they induce. In this paper, we propose to associate to each feature a piece of information about the context in which the feature appears in the graph. A substructure appearing in two different graphs will match only if it appears with the same context in both graphs. We propose a kernel based on this idea that considers trees as substructures, and where the contexts are features too. The kernel is inspired from the framework in [6], even if it is not part of it. We give an efficient algorithm for computing the kernel and show promising results on real-world graph classification datasets.Comment: To appear in ICONIP 201

    Investigation of high pt_{t} events in Nucleus-Nucleus collisions using the Hijing event generator

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    In recent years lot of interest has been observed in the nucleus-nucleus collisions at RHIC energies in phenomena related to high ptp_{t} physics \cite{ref1}. The suppression of high ptp_{t} particles and disappearance of back-to-back jets compared to the scaling with number of binary nucleon-nucleon collisions indicates that a nearly perfect liquid is produced in these collisions. Results on self shadowing of high ptp_{t} events are presented using hadron multiplicity associated to high ptp_{t} and unbiased events in nucleus-nucleus collisions \cite{ref2} obtained from the hijing event generator.Comment: 4 pages, 3 figures, Proceedings of the poster presented at Quark Matter 200

    Comparative Outcomes of Resident vs Attending Performed Surgery: A Systematic Review and Meta-Analysis

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    OBJECTIVE: To determine whether outcomes are different when surgery is performed by resident or attending surgeons, and which variables may affect outcomes. DESIGN: MEDLINE, EMBASE, and the Cochrane Library were searched from inception to May 2014 alongside the bibliographies of all included or relevant studies. Any study comparing outcomes from surgery performed by resident vs attending surgeons was eligible for inclusion. The main outcome measures were surgical complications (classified by Clavien-Dindo grade), death, operative time, and length of stay. Data were extracted independently by 2 authors and analyzed using the random-effects model. RESULTS: The final analysis included 182 eligible studies that enrolled 141 555 patients. Resident performed surgery took longer by 10.2 minutes (95% confidence interval (CI): 8.38-11.95), and had more Clavien-Dindo grade 1 (rate ratio = 1.14, 95% CI: 1.02-1.29) and grade 3a complications (rate ratio = 1.22, 95% CI: 1.04-1.44). Resident performed surgery resulted in fewer deaths (risk ratio = 0.83, 95% CI: 0.70-0.999) with a shorter length of stay of -0.49 days (95% CI: -0.77 to -0.21). Significant heterogeneity was present in 7 of 10 outcomes, which persisted during multiple subgroup analyses. CONCLUSIONS: Resident performed surgery appears to be safe in carefully selected patients. The significant amount of heterogeneity present in the study outcomes prevents generalizability of these results to specific clinical contexts
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