3,269 research outputs found

    Investigation of a generalized Obukhov Model for Turbulence

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    We introduce a generalization of Obukhov's model [A.M. Obukhov, Adv. Geophys. 6, 113 (1959)] for the description of the joint position-velocity statistics of a single fluid particle in fully developed turbulence. In the presented model the velocity is assumed to undergo a continuous time random walk. This takes into account long time correlations. As a consequence the evolution equation for the joint position-velocity probability distribution is a Fokker-Planck equation with a fractional time derivative. We determine the solution of this equation in the form of an integral transform and derive a relation for arbitrary single time moments. Analytical solutions for the joint probability distribution and its moments are given.Comment: 10 page

    Public perceptions of sharks: Gathering support for shark conservation

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    With increasing evidence of the destructive impacts of human activities on the ocean there is a growing call for stronger public engagement in marine governance. An understanding of marine issues and pro-environmental values are key elements that influence an individual[U+05F3]s engagement in conservation and pro-environmental behaviour. This paper presents a study on public perceptions of sharks and shark conservation in the UK. The study investigated knowledge of and attitudes towards sharks of a group of individuals with a clear interest in the marine environment, as well as possible factors that might influence their perceptions of sharks, in order to make recommendations on how to foster engagement in shark conservation. The key finding was that important prerequisites for engagement in shark conservation exist among parts of the UK public. However, this does not seem to be enough to motivate actual engagement. The study discusses a number of specific challenges with regard to sharks which might be influencing the way in which society connects to shark related issues. It concludes with priority recommendations for further investigation into potential catalysts for public engagement in shark conservation. © 2014 Elsevier Ltd

    Gedichte. Bd. 1

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    http://tartu.ester.ee/record=b2410205~S1*es

    Die Taufe und die Todtenfeier : zwei poetische Versuche

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    http://tartu.ester.ee/record=b2410209~S1*es

    Does rating the operation videos with a checklist score improve the effect of E-learning for bariatric surgical training? Study protocol for a randomized controlled trial

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    Background: Laparoscopic training has become an important part of surgical education. Laparoscopic Roux-en-Y gastric bypass (RYGB) is the most common bariatric procedure performed. Surgeons must be well trained prior to operating on a patient. Multimodality training is vital for bariatric surgery. E-learning with videos is a standard approach for training. The present study investigates whether scoring the operation videos with performance checklists improves learning effects and transfer to a simulated operation. Methods/design: This is a monocentric, two-arm, randomized controlled trial. The trainees are medical students from the University of Heidelberg in their clinical years with no prior laparoscopic experience. After a laparoscopic basic virtual reality (VR) training, 80 students are randomized into one of two arms in a 1:1 ratio to the checklist group (group A) and control group without a checklist (group B). After all students are given an introduction of the training center, VR trainer and laparoscopic instruments, they start with E-learning while watching explanations and videos of RYGB. Only group A will perform ratings with a modified Bariatric Objective Structured Assessment of Technical Skill (BOSATS) scale checklist for all videos watched. Group B watches the same videos without rating. Both groups will then perform an RYGB in the VR trainer as a primary endpoint and small bowel suturing as an additional test in the box trainer for evaluation. Discussion: This study aims to assess if E-learning and rating bariatric surgical videos with a modified BOSATS checklist will improve the learning curve for medical students in an RYGB VR performance. This study may help in future laparoscopic and bariatric training courses. Trial registration: German Clinical Trials Register, DRKS00010493. Registered on 20 May 2016

    Reply to Comment on "High-Precision Determination of the Electric and Magnetic Form Factors of the Proton"

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    In arXiv:1108.3058v1 [nucl-ex], Arrington criticizes the Coulomb corrections we applied in the analysis of high precision form factor data (see Phys.Rev.Lett.105:242001, 2010, arXiv:1007.5076v3 [nucl-ex]). We show, by comparing different calculations cited in the Comment, that the criticism of the Comment neglects the large uncertainty of "more modern" TPE corrections. This uncertainty has also been seen in recent polarized measurements. We rerun our analysis using one of these calculations. The results show that the Comment exaggerates the quantitative effect at small Q^2.Comment: 1 page, 2 figure, To appear as a Reply Comment in Physical Review Letter

    High-precision determination of the electric and magnetic form factors of the proton

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    New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q^2=1 (GeV/c)^2 with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be r_E=0.879(5)(stat.)(4)(syst.)(2)(model)(4)(group) fm and r_M=0.777(13)(stat.)(9)(syst.)(5)(model)(2)(group) fm.Comment: 5 pages, 2 figures, published in Phys. Rev. Lett. v3: added references, updated text, color figure
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