60,460 research outputs found
Biomechanics
Biomechanics is a vast discipline within the field of Biomedical Engineering. It explores the underlying mechanics of how biological and physiological systems move. It encompasses important clinical applications to address questions related to medicine using engineering mechanics principles. Biomechanics includes interdisciplinary concepts from engineers, physicians, therapists, biologists, physicists, and mathematicians. Through their collaborative efforts, biomechanics research is ever changing and expanding, explaining new mechanisms and principles for dynamic human systems. Biomechanics is used to describe how the human body moves, walks, and breathes, in addition to how it responds to injury and rehabilitation. Advanced biomechanical modeling methods, such as inverse dynamics, finite element analysis, and musculoskeletal modeling are used to simulate and investigate human situations in regard to movement and injury. Biomechanical technologies are progressing to answer contemporary medical questions. The future of biomechanics is dependent on interdisciplinary research efforts and the education of tomorrow’s scientists
Superscaling of non-quasielastic electron-nucleus scattering
The present study is focused on the superscaling behavior of electron-nucleus
cross sections in the region lying above the quasielastic peak, especially the
region dominated by electroexcitation of the Delta. Non-quasielastic cross
sections are obtained from all available high-quality data for Carbon 12 by
subtracting effective quasielastic cross sections based on the superscaling
hypothesis. These residuals are then compared with results obtained within a
scaling-based extension of the relativistic Fermi gas model, including an
investigation of violations of scaling of the first kind in the region above
the quasielastic peak. A way potentially to isolate effects related to
meson-exchange currents by subtracting both impulsive quasielastic and
impulsive inelastic contributions from the experimental cross sections is also
presented.Comment: RevTeX, 34 pages including 11 figure
A Neural Circuit Model for Prospective Control of Interceptive Reaching
Two prospective controllers of hand movements in catching -- both based on required velocity control -- were simulated. Under certain conditions, this required velocity controlled to overshoots of the future interception point. These overshoots were absent in pertinent experiments. To remedy this shortcoming, the required velocity model was reformulated in terms of a neural network, the Vector Integration To Endpoint model, to create a Required Velocity Integration To Endpoint modeL Addition of a parallel relative velocity channel, resulting in the Relative and Required Velocity Integration To Endpoint model, provided a better account for the experimentally observed kinematics than the existing, purely behavioral models. Simulations of reaching to intercept decelerating and accelerating objects in the presence of background motion were performed to make distinct predictions for future experiments.Vrije Universiteit (Gerrit-Jan van Jngen-Schenau stipend of the Faculty of Human Movement Sciences); Royal Netherlands Academy of Arts and Sciences; Defense Advanced Research Projects Agency and Office of Naval Research (N00014-95-1-0409
Using Electron Scattering Superscaling to predict Charge-changing Neutrino Cross Sections in Nuclei
Superscaling analyses of few-GeV inclusive electron scattering from nuclei
are extended to include not only quasielastic processes, but now also into the
region where -excitation dominates. It is shown that, with reasonable
assumptions about the basic nuclear scaling function extracted from data and
information from other studies of the relative roles played by correlation and
MEC effects, the residual strength in the resonance region can be accounted for
through an extended scaling analysis. One observes scaling upon assuming that
the elementary cross section by which one divides the residual to obtain a new
scaling function is dominated by the transition and employing a
new scaling variable which is suited to the resonance region. This yields a
good representation of the electromagnetic response in both the quasielastic
and regions. The scaling approach is then inverted and predictions are
made for charge-changing neutrino reactions at energies of a few GeV, with
focus placed on nuclei which are relevant for neutrino oscillation
measurements. For this a relativistic treatment of the required weak
interaction vector and axial-vector currents for both quasielastic and
-excitation processes is presented.Comment: 42 pages, 9 figures, accepted for publication in Physical Review
Modeling the kinematics and Dynamics of Compliant Contact
In this paper, we discuss the modeling of the kinematics and dynamics of compliant contact between bodies moving in Euclidean space. First, we derive the kinematic equations describing the motion of the contact point when two rigid bodies are rolling on each other. Secondly, we extend these results to describe the motion of the closest points between two rigid bodies moving freely in space. Then, we use these results to model compliant contact between bodies, using a spatial spring and a damper to model energy stored and dissipated during contact
Kinematics and Mass Modeling of Messier 33: Halpha observations
As part of a long-term project to revisit the kinematics and dynamics of the
large disc galaxies of the Local Group, we present the first deep, wide-field
(42' x 56') 3D-spectroscopic survey of the ionized gas disc of Messier 33.
Fabry-Perot interferometry has been used to map its Ha distribution and
kinematics at unprecedented angular resolution (<3'') and resolving power
(12600), with the 1.6m telescope at the Observatoire du Mont Megantic. The
ionized gas distribution follows a complex, large-scale spiral structure,
unsurprisingly coincident with the already-known spiral structures of the
neutral and molecular gas discs. The kinematical analysis of the velocity field
shows that the rotation center of the Ha disc is distant from the photometric
center by 170 pc (sky projected distance) and that the kinematical major-axis
position angle and disc inclination are in excellent agreement with photometric
values. The Ha rotation curve agrees very well with the HI rotation curves for
0 6.5 kpc.
The reason for this discrepancy is not well understood. The velocity dispersion
profile is relatively flat around 16 km/s, which is at the low end of velocity
dispersions of nearby star-forming galactic discs. A strong relation is also
found between the Ha velocity dispersion and the Ha intensity. Mass models were
obtained using the Ha rotation curve but, as expected, the dark matter halo's
parameters are not very well constrained since the optical rotation curve only
extends out to 8 kpc.Comment: 26 pages, 18 figures, accepted for publication in MNRA
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