375 research outputs found
Biomechanical role and motion contribution of ligaments and bony constraints in the elbow stability: A preliminary study
In flexion-extension motion, the interaction of several ligaments and bones characterizes the elbow joint stability. The aim of this preliminary study was to quantify the relative motion of ulna respect to humerus in two human elbow specimens and to investigate the constraints role for maintaining the joint stability in different dissections condition. Two clusters of 4 markers were fixed respectively to ulna and humerus, and their trajectory was recorded by a motion capture system during orthopedic maneuver. Considering the medial ulnar collateral posterior bundle (pMUCL) and the coronoid, two dissection sequences were executed. The orthopedic maneuver of compression, pronation and varus force was repeated at 30°, 60°, 90° flexion for the functional investigation of constraints. Ulna deflection was compared to a baseline flexion condition. Respect to intact elbow, the coronoid osteotomy influences the elbow stability at 90° (deflection=11.49±17.39 mm), while small differences occur at 30° and 60°, due to ligaments constraint. The contemporary pMUCL dissection and coronoid osteotomy causes elbow instability, with large deflection at 30° (deflection=34.40±9.10 mm), 60° (deflection=45.41±18.47 mm) and 90° (deflection=52.16±21.92 mm). Surgeons may consider the pMUCL reconstruction in case of unfixable coronoid fracture
Penrose type inequalities for asymptotically hyperbolic graphs
In this paper we study asymptotically hyperbolic manifolds given as graphs of
asymptotically constant functions over hyperbolic space \bH^n. The graphs are
considered as subsets of \bH^{n+1} and carry the induced metric. For such
manifolds the scalar curvature appears in the divergence of a 1-form involving
the integrand for the asymptotically hyperbolic mass. Integrating this
divergence we estimate the mass by an integral over an inner boundary. In case
the inner boundary satisfies a convexity condition this can in turn be
estimated in terms of the area of the inner boundary. The resulting estimates
are similar to the conjectured Penrose inequality for asymptotically hyperbolic
manifolds. The work presented here is inspired by Lam's article concerning the
asymptotically Euclidean case.Comment: 29 pages, no figure, includes a proof of the equality cas
Ess target performance for different beam pulses
Last trends in the design of linear accelerators for high power spallation sources point to the use of ion beams of larger energies and shorter pulse lengths in order to enhance the reliability of the system. In this sense the recommendations for ESS are to increase the energy of the proton beam from 1.3GeV to 2-2.5GeV and to reduce the length of the beam pulse from 2ms to 1-1.5ms, keeping the source average power at 5MW. Different values for the repetition rate are also being discussed (16 2/3, 20, 25 Hz). ESS Bilbao is analyzing the impact of these modifications on the design of the target system. In this paper the effects of the different beam energies on the target disc thermohydraulics and the neutron performance of the source are discussed. Initial calculations were performed for a rotating target with ESS 2002 parameters. During the development of the work âthat are being performed in collaboration with SNSâ the decision was made to use the SNS-STS Target-Moderator-Reflector Assembly (TMRA) âslightly modified to accommodate the target design being studied for ESSâ which presents a state of the art design with a cylindrical liquid para-hydrogen moderator in wing configuration aimed to enhance cold neutron productio
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Factors influencing spawner success in a spring Chinook salmon (Oncorhynchus tshawytscha) reintroduction program
Dams have contributed to the decline of migratory fishes by blocking access to historical habitat. The active transport (trap and haul) of migratory fish species above existing dams can sometimes support population recovery when the use of fish ladders or dam removal is infeasible. However, little is known about the efficacy of trap and haul conservation strategies. Here we used genetic parentage assignments to evaluate the efficacy of reintroducing adult Chinook salmon above Cougar Dam on the South Fork McKenzie River, Oregon, USA from 2008-2011. We found that mean reproductive success (RS) declined as adults were released later in the spawning season in 2009 and 2010; however release location did not affect RS. In 2010 and 2011, we tested for RS differences between hatchery and natural origin (HOR and NOR) adults. HOR males were consistently less fit than NOR males, but little evidence for fitness differences was apparent between HOR and NOR females. Interestingly, the effect of origin on RS was not significant after accounting for variation explained by body length. Our results indicate that release date and location have inconsistent or no effect on the reproductive success of reintroduced adults when active transport strategies are employed for migratory fishes.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Canadian Science Publishing, NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/10.1139/cjfas-2015-0007#.VuHGB3rci0jKeywords: hatchery and natural origin, reproductive success, genetic parentage, reintroduction, active transportKeywords: hatchery and natural origin, reproductive success, genetic parentage, reintroduction, active transpor
REMOVABLE SETS FOR LIPSCHITZ HARMONIC FUNCTIONS ON CARNOT GROUPS
Abstract. Let G be a Carnot group with homogeneous dimension Q â„ 3 and let L be a sub-Laplacian on G. We prove that the critical dimension for removable sets of Lipschitz L-harmonic functions is (Q â 1). Moreover we construct self-similar sets with positive and finite H Qâ1 measure which are removable. 1
Adaptation of the generic PDE's results to the notion of prevalence
Many generic results have been proved, especially concerning the qualitative
behaviour of solutions of partial differential equations. Recently, a new
notion of "almost always", the prevalence, has been developped for vectorial
spaces. This notion is interesting since, for example, prevalence sets are
equivalent to the full Lebesgue measure sets in finite dimensional spaces. The
purpose of this article is to adapt the generic PDE's results to the notion of
prevalence. In particular, we consider the cases where Sard-Smale theorems or
arguments of analytic perturbations of the parameters are used
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Search for charmed particles
We propose to use the CCM spectrometer to carry out a sensitive search for charmed particles produced in strong interactions at a nominal beam energy of 150 GeV/c. We limit ourselves to production in the beam diffraction region for reasons of acceptance and reconstruction. We present results of a test run undertaken in April 1975 to demonstrate the feasibility of K{sub S}{sup 0} trigger, which we incorporate in the present proposal. Results of the test are combined with new insights which increase our sensitivity to charmed particle production by a large factor. We request a total of 2 x 10{sup 11} negative pions at a rate of 10{sup 6} per pulse. With this illumination we estimate that we can measure a large number of hadronic decay modes. We make estimates of enhancements in mass spectra from charmed particle production and decay and calculate expected backgrounds using data from existing experiments. With conservative assumptions about the charmed particle model, we calculate effects corresponding to ten or more standard deviations in our most favorable channels
The Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission
86 pags., 49 figs., 24 tabs.NASAâs Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at âŒ1.5 m and âŒ0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.This work has been funded by the Spanish Ministry of Economy and Competitiveness, through the projects No. ESP2014-54256-C4-1-R (also -2-R, -3-R and -4-R) and AYA2015-65041-P; Ministry of Science, Innovation and Universities, projects No. ESP2016-79612-C3-1-R (also -2-R and -3-R),
ESP2016-80320-C2-1-R, RTI2018-098728-B-C31 (also -C32 and -C33) and RTI2018-099825-B-C31; Instituto Nacional de TĂ©cnica Aeroespacial; Ministry of Science and Innovationâs Centre for the Development of Industrial Technology; Grupos Gobierno Vasco IT1366-19; and European Research Council Consolidator Grant no 818602. The US co-authors performed their work under sponsorship from NASAâs Mars 2020 project, from the
Game Changing Development program within the Space Technology Mission Directorate and from the Human Exploration and Operations Directorate
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