142 research outputs found

    Preliminary measurements of lumbar spine kinematics and stiffness

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    The purpose of the presented study was the experimental measurement of lumbar spine stiffness and its range of motion. The dependence of torsion moment of lumbar spine segment on deflection of flexion, extension and torsion was observed during experiments. Stiffness of spine segment was determined from measured data. Human lumbar spine was used for verification of the experimental technique. The sample consisted of one lumbar vertebrae composed by five vertebral bodies and four intervertebral discs. All muscles were removed, however all ligaments were preserved. Experiments were ca rried out on the test system MTS 858.2 MiniBionix, where loading by axial force and torsion moment is possible at the same time. Special Modular Bionix Spine Test Fixator, attached to the test system was used for the measurements. Loading was controlled kinematically (gradual turning) by keeping the axial force equal zero. Measurement was timedependent. The results of these experiments are going to be used as input data for creating a model of artificial lumbar spine and new type of artificial disc replacement

    Hadro-Chemistry and Evolution of (Anti-) Baryon Densities at RHIC

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    The consequences of hadro-chemical freezeout for the subsequent hadron gas evolution in central heavy-ion collisions at RHIC and LHC energies are discussed with special emphasis on effects due to antibaryons. Contrary to naive expectations, their individual conservation, as implied by experimental data, has significant impact on the chemical off-equilibrium composition of hadronic matter at collider energies. This may reflect on a variety of observables including source sizes and dilepton spectra.Comment: 4 pages ReVTeX incl. 3 ps-figs, submitted to PR

    Thermal analysis of production of resonances in relativistic heavy-ion collisions

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    Production of resonances is considered in the framework of the single-freeze-out model of ultra-relativistic heavy ion collisions. The formalism involves the virial expansion, where the probability to form a resonance in a two-body channel is proportional to the derivative of the phase-shift with respect to the invariant mass. The thermal model incorporates longitudinal and transverse flow, as well as kinematic cuts of the STAR experiment at RHIC. We find that the shape of the pi+ pi- spectral line qualitatively reproduces the preliminary experimental data when the position of the rho peak is lowered. This confirms the need to include the medium effects in the description of the RHIC data. We also analyze the transverse-momentum spectra of rho, K*(892), and f_0(980), and find that the slopes agree with the observed values. Predictions are made for eta, eta', omega, phi, Lambda(1520), and Sigma(1385).Comment: minor modifications, a reference adde

    3D Fluid Flow Estimation with Integrated Particle Reconstruction

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    The standard approach to densely reconstruct the motion in a volume of fluid is to inject high-contrast tracer particles and record their motion with multiple high-speed cameras. Almost all existing work processes the acquired multi-view video in two separate steps, utilizing either a pure Eulerian or pure Lagrangian approach. Eulerian methods perform a voxel-based reconstruction of particles per time step, followed by 3D motion estimation, with some form of dense matching between the precomputed voxel grids from different time steps. In this sequential procedure, the first step cannot use temporal consistency considerations to support the reconstruction, while the second step has no access to the original, high-resolution image data. Alternatively, Lagrangian methods reconstruct an explicit, sparse set of particles and track the individual particles over time. Physical constraints can only be incorporated in a post-processing step when interpolating the particle tracks to a dense motion field. We show, for the first time, how to jointly reconstruct both the individual tracer particles and a dense 3D fluid motion field from the image data, using an integrated energy minimization. Our hybrid Lagrangian/Eulerian model reconstructs individual particles, and at the same time recovers a dense 3D motion field in the entire domain. Making particles explicit greatly reduces the memory consumption and allows one to use the high-res input images for matching. Whereas the dense motion field makes it possible to include physical a-priori constraints and account for the incompressibility and viscosity of the fluid. The method exhibits greatly (~70%) improved results over our recently published baseline with two separate steps for 3D reconstruction and motion estimation. Our results with only two time steps are comparable to those of sota tracking-based methods that require much longer sequences.Comment: To appear in International Journal of Computer Vision (IJCV

    Three-Dimensional two-pion source image from Pb+Pb Collisions at Sqrts_NN=17.3 GeV: New constraints for source breakup dynamics

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    Source imaging methodology is used to provide a three-dimensional two-pion source function for mid-rapidity pion pairs with pT<70p_T<70 MeV/c in central (0−70-7%) Pb+Pb collisions at sNN\sqrt s_{NN}=17.3 GeV. Prominent non-Gaussian tails are observed in the pion pair transverse momentum (outward) and in the beam (longitudinal) directions. Model calculations reproduce them with the assumption of Bjorken longitudinal boost invariance and transverse flow blast-wave dynamics coupled with "outside-in burning" in the transverse direction; they also yield a proper time for breakup and emission duration for the pion source.Comment: Six pages 4 figs. Submitted for publicatio

    Reconciling the professional and student identities of clinical psychology trainees

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    The study explored the ways in which qualified and trainee clinical psychologists perceived professional behaviour, as illustrated in a series of short vignettes, in student and clinical practice contexts. Comparisons were made to identify the extent to which ideas of professionalism differed across different learning contexts and between qualified and unqualified staff, with the aim of adding to the literature on which factors influence the development of professional identity in health professionals. An online questionnaire depicting a range of potentially unprofessional behaviours was completed by 265 clinical psychology trainees and 106 qualified clinical psychologists. The data were analysed using a general linear model with simultaneous entry in which rater (trainee vs qualified clinical psychologist), setting (student vs placement) and their interaction predicted acceptability ratings. We found that, in general, trainees and qualified staff agreed on those behaviours that were potentially unprofessional, although where significant differences were found, these were due to trainees rating the same behaviours as more professionally acceptable than qualified clinical psychologists. Despite trainees identifying a range of behaviours as professionally unacceptable, some percentage reported having engaged in a similar behaviour in the past. Irrespective of the status of the rater, the same behaviours tended to be viewed as more professionally unacceptable when in a placement (clinical) setting than in a student (university) setting. Generally, no support was found for a rater by setting interaction. The study suggests that trainee clinical psychologists are generally successful at identifying professional norms, although they do not always act in accordance with these. Conflicting student and professional norms may result in trainees viewing some potentially unprofessional behaviour as less severe than qualified staff. Health professional educators should be aware of this fact and take steps to shape trainee norms to be consistent with that of the professional group

    The Heroic and the Villainous: a qualitative study characterising the role models that shaped senior doctors’ professional identity

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    The successful development and sustaining of professional identity is critical to being a successful doctor. This study explores the enduring impact of significant early role models on the professional identity formation of senior doctors.Personal Interview Narratives were derived from the stories told by twelve senior doctors as they recalled accounts of people and events from the past that shaped their notions of being a doctor. Narrative inquiry methodology was used to explore and analyse video recording and transcript data from interviews.Role models were frequently characterised as heroic, or villainous depending on whether they were perceived as good or bad influences respectively. The degree of sophistication in participants' characterisations appeared to correspond with the stage of life of the participant at the time of the encounter. Heroes were characterised as attractive, altruistic, caring and clever, often in exaggerated terms. Conversely, villains were typically characterised as direct or covert bullies. Everyday events were surprisingly powerful, emotionally charged and persisted in participants' memories much longer than expected. In particular, unresolved emotions dating from encounters where bullying behaviour had been witnessed or experienced were still apparent decades after the event.The characterisation of role models is an important part of the professional identity and socialisation of senior doctors. The enduring impact of what role models say and do means that all doctors, need to consistently reflect on how their own behaviour impacts the development of appropriate professional behaviours in both students and training doctors. This is especially important where problematic behaviours occur as, if not dealt with, they have the potential for long-lasting undesirable effects. The importance of small acts of caring in building a nurturing and supportive learning atmosphere at all stages of medical education cannot be underestimated
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