2,359 research outputs found
Data science of stroke imaging and enlightenment of the penumbra.
Imaging protocols of acute ischemic stroke continue to hold significant uncertainties regarding patient selection for reperfusion therapy with thrombolysis and mechanical thrombectomy. Given that patient inclusion criteria can easily introduce biases that may be unaccounted for, the reproducibility and reliability of the patient screening method is of utmost importance in clinical trial design. The optimal imaging screening protocol for selection in targeted populations remains uncertain. Acute neuroimaging provides a snapshot in time of the brain parenchyma and vasculature. By identifying the at-risk but still viable penumbral tissue, imaging can help estimate the potential benefit of a reperfusion therapy in these patients. This paper provides a perspective about the assessment of the penumbral tissue in the context of acute stroke and reviews several neuroimaging models that have recently been developed to assess the penumbra in a more reliable fashion. The complexity and variability of imaging features and techniques used in stroke will ultimately require advanced data driven software tools to provide quantitative measures of risk/benefit of recanalization therapy and help aid in making the most favorable clinical decisions
Q-ball formation at the deconfinement temperature in large- QCD
The deconfinement phase transition in large- QCD is studied within the
framework of an effective Polyakov-loop model, where the potential has a U(1)
symmetry originating in the large- limit of a Z-symmetric model.
At the critical temperature, the shape of the effective potential allows the
existence of Q-balls as position-dependent fluctuations of the Polyakov loop.
Q-balls with spherical or axial symmetry are numerically obtained from the
equations of motion of the effective model under consideration. The physical
properties of these non-topological solitons (mass, charge and size) are
discussed, as well as their interpretation in terms of spinning "bubbles", with
various shapes, of deconfined matter surrounded by a confined environment.Comment: 21 pages, 8 figures ; v2 matches the published versio
On the effect of rotation on magnetohydrodynamic turbulence at high magnetic Reynolds number
This article is focused on the dynamics of a rotating electrically conducting
fluid in a turbulent state. As inside the Earth's core or in various industrial
processes, a flow is altered by the presence of both background rotation and a
large scale magnetic field. In this context, we present a set of 3D direct
numerical simulations of incompressible decaying turbulence. We focus on
parameters similar to the ones encountered in geophysical and astrophysical
flows, so that the Rossby number is small, the interaction parameter is large,
but the Elsasser number, defining the ratio between Coriolis and Lorentz
forces, is about unity. These simulations allow to quantify the effect of
rotation and thus inertial waves on the growth of magnetic fluctuations due to
Alfv\'en waves. Rotation prevents the occurrence of equipartition between
kinetic and magnetic energies, with a reduction of magnetic energy at
decreasing Elsasser number {\Lambda}. It also causes a decrease of energy
transfer mediated by cubic correlations. In terms of flow structure, a decrease
of {\Lambda} corresponds to an increase in the misalignment of velocity and
magnetic field.Comment: 18 pages, 12 figure
Developing a systems and informatics based approach to lifestyle monitoring within eHealth:part I - technology and data management
Lifestyle monitoring forms a subset of telecare in which data derived from sensors located in the home is used to identify variations in behaviour which are indicative of a change in care needs. Key to this is the performance of the sensors themselves and the way in which the information from multiple sources is integrated within the decision making process. The paper therefore considers the functions of the key sensors currently deployed and places their operation within the context of a proposed multi-level system structure which takes due cognisance of the requisite informatics framework
Bound state equivalent potentials with the Lagrange mesh method
The Lagrange mesh method is a very simple procedure to accurately solve
eigenvalue problems starting from a given nonrelativistic or semirelativistic
two-body Hamiltonian with local or nonlocal potential. We show in this work
that it can be applied to solve the inverse problem, namely, to find the
equivalent local potential starting from a particular bound state wave function
and the corresponding energy. In order to check the method, we apply it to
several cases which are analytically solvable: the nonrelativistic harmonic
oscillator and Coulomb potential, the nonlocal Yamaguchi potential and the
semirelativistic harmonic oscillator. The potential is accurately computed in
each case. In particular, our procedure deals efficiently with both
nonrelativistic and semirelativistic kinematics.Comment: 6 figure
Relativistic corrections for two- and three-body flux tube model
We generalize the relativistic flux tube model for arbitrary two- or
three-body systems. The spin-independent and spin-dependent contributions of
the flux tube to the total Hamiltonian are computed in perturbation. In
particular, we show that the spin-dependent part exhibits a universal
spin-orbit form: It does not depend on the nature of the confined particles.
The general equations we present, being well-defined for light particles, can
thus be applied to usual as well as exotic hadrons such as hybrid mesons and
glueballs.Comment: 10 pages; v2 accepted for publication (minor changes
A Multi-Modal Continuous-Systems Model of a Novel High-Q Disk Resonator in a Viscous Liquid
International audienc
Analytical Modeling of a Novel High-\u3cem\u3eQ\u3c/em\u3e Disk Resonator for Liquid-Phase Applications
To overcome the detrimental effects of liquid environments on microelectromechanical systems resonator performance, the in-fluid vibration of a novel disk resonator supported by two electrothermally driven legs is investigated through analytical modeling and the effects of the system’s geometric/material parameters on the dynamic response are explored. The all-shear interaction device (ASID) is based on engaging the surrounding fluid primarily through shearing action. The theory comprises a continuous-system, multimodal model, and a single-degree-of-freedom model, the latter yielding simple formulas for the fundamental-mode resonant characteristics that often furnish excellent estimates to the results based on the more general model. Comparisons between theoretical predictions and previously published liquid-phase quality factor (Q) data (silicon devices in heptane) show that the theoretical results capture the observed trends and also give very good quantitative estimates, particularly for the highest Q devices. Moreover, the highest Q value measured in the earlier study (304) corresponded to a specimen whose disk radius-to-thickness ratio was 2.5, a value that compares well with the optimal value of 2.3 predicted by the present model. The insight furnished by the proposed theory is expected to lead to further improvements in ASID design to achieve unprecedented levels of performance for a wide variety of liquid-phase resonator applications
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