1,283 research outputs found

    Incidents and injuries in foot launched flying extreme sports: a snap shot from the UK

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    Background. Participation rates in extreme sports have grown exponentially in the last 40 years,often surpassing traditional sporting activities. The purpose of this study was to examine injury rates in foot launched flying sports, i.e. sports in which a pilot foot-launches into flight with a wing already deployed. Method. This paper is based on a retrospective analysis of the reports of incidents that occurred between 2000 and 2014 among the British Hang Gliding and Paragliding Association members. Results. The majority of the 1411 reported injuries were in the lower limb, followed by the upper limb. The most common lower limb injury was to the ankle and included fractures sprains and dislocations. The distribution of injures was different in each discipline. The calculated yearly fatality rate (fatalities /100,000 participants) was 40.4 in hang gliding, 47.1 in paragliding, 61.9 in powered hang gliding and 83.4 in powered paragliding; the overall value for foot launched flight sports was 43.9. Discussion. Significant differences in injury rates and injury patterns were found among different sport disciplines that can be useful to steer research on safety, and adopt specific safety rules about flying, protective clothing and safety systems in each of these sports

    Comparison Between the Biomechanical Responses of the Hand and Foot When Exposed to Vertical Vibration

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    Workers can be exposed daily to foot-transmitted vibration (FTV) from standing on mobile equipment or vibrating platforms and surfaces. This results in a consistent risk of developing neurological, vascular, and musculoskeletal problems. To date, there are no international stand-ards describing procedures with which to evaluate the health risks deriving from long-term ex-posure to FTV. To study the applicability of hand–arm vibration (HAV) standards to the foot, the biomechanical responses of the hand and foot in terms of the frequency response function upon varying contact conditions were compared. Results evidenced similarities between the responses of the wrist and ankle, with differences in resonance for the fingers and toes. The study confirms that HAV standards are more suitable than whole-body vibration standards for evaluating higher frequency exposure to FTV

    Deployment requirements for deorbiting electrodynamic tether technology

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    In the last decades, green deorbiting technologies have begun to be investigated and have raised a great interest in the space community. Among the others, electrodynamic tethers appear to be a promising option. By interacting with the surrounding ionosphere, electrodynamic tethers generate a drag Lorentz force to decrease the orbit altitude of the satellite, causing its re-entry in the atmosphere without using propellant. In this work, the requirements that drive the design of the deployment mechanism proposed for the H2020 Project E.T.PACK\u2014Electrodynamic Tether Technology for Passive Consumable-less Deorbit Kit\u2014are presented and discussed. Additionally, this work presents the synthesis of the reference profiles used by the motor of the deployer to make the tethered system reach the desired final conditions. The result is a strategy for deploying electrodynamic tape-shaped tethers used for deorbiting satellites at the end of their operational life

    Deorbit kit demonstration mission

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    In Low Earth Orbit, it is possible to use the ambient plasma and the geomagnetic field to exchange momentum with the Earth's magnetosphere without using propellant. A device that allows an efficient momentum exchange is the electrodynamic tether (EDT), a long conductor attached to the satellite. EDT technology has been demonstrated in several past missions, being the Plasma Motor Generator mission (NASA 1993) one of the most successful. Nevertheless, it is not until today that reality has imposed a strong need and a concrete use case for developing this technology. In March 2019, the European Commission project Electrodynamic Tether technology for PAssive Consumable-less deorbit Kit (E.T.PACK) started the design of a new generation EDT. After completing the design phase, the consortium manufactured and is currently testing a Deorbit Kit Demonstrator (DKD) breadboard based on EDT technology. The objective of E.T.PACK is to reach Technology Readiness Level equal to 4 by 2022. The DKD is a standalone 24-kg satellite with the objective to demonstrate the performances of the improved EDT solution and validate its ultra-compact deployment system. The DKD is composed of two modules that will separate in orbit extending a 500-m long tape-like tether. The deployed bare-Aluminium tether will capture electrons from the ambient plasma passively and the circuit will be closed with the ionospheric plasma by using an active electron emitter. E.T.PACK tether will take advantage of several novelties with respect to the mission flown in the past that will allow to optimize the system volume and mass. Once successful demonstrated in orbit, the team plans to develop a suite of EDT systems capable of deorbiting satellites between 200 and 1000 kg from an altitude up to 1200 km in a few months. The work presents the current design status of the de-orbit kit demonstrator breadboard, the simulations of the system deorbit performances and the development approach.This work was supported by the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No.828902 (3M€ E.T.PACK project) and No.101034874 (100K€ BMOM project). SG is supported by an Industrial Ph.D funded by Comunidad de Madrid (135K€ IND2019/TIC17198). The team has recently got 2.5M€ additional financial support from European Union (ETPACK-F project No. 101058166) for the manufacturing and qualification of the In Orbit Demonstration (IOD) by the end of 2025

    Four degree-of-freedom lumped parameter model of the foot-ankle system exposed to vertical vibration from 10 to 60 Hz with varying centre of pressure conditions

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    Modelling the foot-ankle system (FAS) while exposed to foot-transmitted vibration (FTV) is essential for designing inhibition methods to prevent the effects of vibration-induced white-foot. K-means analysis was conducted on a data set containing vibration transmissibility from the floor to 24 anatomical locations on the right foot of 21 participants. The K-means analysis found three locations to be sufficient for summarising the FTV response. A three segment, four degrees-of-freedom lumped parameter model of the FAS was designed to model the transmissibility response at three locations when exposed to vertical vibration from 10 to 60 Hz. Reasonable results were found at the ankle, midfoot, and toes in the natural standing position (mean-squared error (Δ) = 0.471, 0.089, 0.047) and forward centre of pressure (COP) (Δ = 0.539, 0.058, 0.057). However, when the COP is backward, the model does not sufficiently capture the transmissibility response at the ankle (Δ = 1.09, 0.219, 0.039).This work was supported by a Natural Science and Engineering Council of Canada Discovery Grant [RGPIN/ 4252-2015]

    La estrategia Educativa 2020 o las limitaciones del Banco Mundial para promover el "aprendizaje para todos"

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    La nueva Estrategia Educativa 2020 del Banco Mundial establece las prioridades de reforma educativa en paises en vias de desarrollo para la decada siguiente. El titulo explicito de la estrategia, Aprendizaje para Todos, es un claro reconocimiento de que, mas alla de politicas centradas en el acceso, se debe hacer algo mas para asegurar que la educacion derive en experiencias positivas de aprendizaje. Sin embargo, como este articulo sostiene, las opciones de politicas explicitas y latentes en la Estrategia 2020 no son las mas adecuadas para lograr el Aprendizaje para Todos. El articulo desarrolla tres tipos de argumentos al respecto. El primero se refiere al fuerte apego del Banco a un conocimiento disciplinario y un enfoque metodológico que es insufi ciente para entender lo que aprenden los niños en la escuela y por que. El segundo argumento se refiere al sesgo pro-mercado de la Estrategia por lo que respecta a la reforma del sector publico y a nuevas formas de oferta educativa. En tercer lugar, el articulo senala las principales ausencias de la Estrategia, con especial atencion a las omisiones relacionadas con la compleja relación entre educación y pobreza.The World Bank's 2020 Education Strategy establishes the new education priorities in developing countries for the next decade. Its title, Learning for All, clearly recognizes that, beyond policies focusing on access, something else must be done to ensure that schooling involves positive learning experiences. However, as this paper argues, the 2020 Strategy explicit and latent policy options might not be adequate to achieve Learning for All. This paper develops three arguments on that matter. The fi rst one refers to the Bank's strong attachment to a disciplinary knowledge and a methodological approach that do not suffi ce to understand what children learn at school and why. The second one addresses its pro-market bias when it approaches the public sector reforms and the new forms of providing education. The last argument points out the main omissions of this Strategy, especially in what regards the complex relation between education and poverty

    La educaciĂłn inclusiva frente a las desigualdades sociales: un estado de la cuestion y algunas reflexiones geograficas

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    Este artĂ­culo establece un estado de la cuestiĂłn e la educaciĂłn inclusiva en el mundo y sugiere algunas reflexiones al respecto. El primer apartado recuerda las conexiones ineludibles entre las preocupaciones educativas por la educaciĂłn inclusiva y las preocupaciones mĂĄs generales por la desigualdad. El segundo consigna los criterios de bĂșsqueda de las publicaciones acadĂ©micas, y observa dos grandes temas en sus contenidos: sobre todo, el cambio interno de las escuelas atrae las miradas, pero en segundo plano tambiĂ©n el entorno territorial despierta algunas inquietudes. El tercero anota los criterios de bĂșsqueda de la documentaciĂłn del Banco Mundial, la OCDE y la UNESCO. En este ĂĄmbito los simposios de la Oficina Internacional de la EducaciĂłn de UNESCO revelan una interpretaciĂłn dispar, aunque convergente, del concepto de educaciĂłn inclusiva en las distintas regiones mundiales. Asimismo, todas las publicaciones oficiales muestran una atenciĂłn prioritaria a las dinĂĄmicas internas de las escuelas, puesto que apenas algunas esbozan ciertas relaciones entre la educaciĂłn inclusiva y las polĂ­ticas pĂșblicas. El Ășltimo apartado adelanta varios argumentos a favor de una mayor consideraciĂłn de las escalas local y estatal de la educaciĂłn inclusiva. Las principales razones para atender a la dimensiĂłn local provienen de la causalidad acumulativa de las privaciones sociales, de la necesidad de articular la acciĂłn de las escuelas y de la posibilidad de abrir un espacio significativo para la participaciĂłn ciudadana. Asimismo, las principales razones para atender a la dimensiĂłn estatal surgen de las posibles sinergias entre la educaciĂłn inclusiva y la expansiĂłn educativa (p. ej. Âżes correlativo el avance de la escolarizaciĂłn en los distintos ciclos escolares?) como tambiĂ©n entre la educaciĂłn inclusiva y la protecciĂłn social (p. ej. Âżtienen una implicaciĂłn pedagĂłgica consistente las abundantes condiciones educativas de las transferencias sociales?

    Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20−-300 GeV/c

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    The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly readout by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.Comment: To be submitted to JINS

    Combined searches for the production of supersymmetric top quark partners in proton–proton collisions at √s=13Te

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    A combination of searches for top squark pair production using proton–proton collision data at a center-of-mass energy of 13TeV at the CERN LHC, corresponding to an integrated luminosity of 137fb−1^{-1} collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325GeV for a massless neutralino, and a neutralino mass up to 700GeV for a top squark mass of 1150GeV. Top squarks with masses from 145 to 295GeV, for neutralino masses from 0 to 100GeV, with a mass difference between the top squark and the neutralino in a window of 30GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420GeV

    Observation of the Bc+_\mathrm{c}^+ Meson in Pb-Pb and pp Collisions at sNN\sqrt{s_{\mathrm{NN}}} = 5.02 TeV and Measurement of its Nuclear Modification Factor

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    The Bc+_\mathrm{c}^+ meson is observed for the first time in heavy ion collisions. Data from the CMS detector are used to study the production of the Bc+_\mathrm{c}^+ meson in lead-lead (Pb-Pb) and proton-proton (pp) collisions at a center-of-mass energy per nucleon pair of sNN\sqrt{s_{\mathrm{NN}}} = 5.02 TeV , via the Bc+_\mathrm{c}^+ → (J/ψ → ÎŒ+^+Ό−^−)ÎŒ+^+ΜΌ_ÎŒ decay. The Bc+_\mathrm{c}^+ nuclear modification factor, derived from the PbPb-to-pp ratio of production cross sections, is measured in two bins of the trimuon transverse momentum and of the PbPb collision centrality. The Bc+_\mathrm{c}^+meson is shown to be less suppressed than quarkonia and most of the open heavy-flavor mesons, suggesting that effects of the hot and dense nuclear matter created in heavy ion collisions contribute to its production. This measurement sets forth a promising new probe of the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma
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