Search results for "SLI"
showing 10 items of 1729 documents
Meßfehlerschätzung bei der MR-tomographischen Volumetrie des linken Ventrikels mit Mehrschicht-Technik
1992
A multi-slice technique for MRT measurements of the left ventricular volume is much faster than the use of single-slice methods and is therefore better tolerated, leaving time for additional measurements. The end-diastolic left ventricular volume can be reliably measured by this method (123.3 +/- 13.5 ml vs. 124.1 +/- ml). The end-systolic volume is consistently overestimated by 23.7 +/- 18.3% compared with the reference value obtained by single slice measurements (47.9 +/- 8.9 ml vs 39.1 +/- 7.9 ml). Correspondingly, stroke volume and ejection fraction is underestimated on average by 10.6 +/- 9.7% and 10.6 +/- 7.6% respectively).
Λc± production in pp collisions with a new fragmentation function
2020
We study inclusive ${\mathrm{\ensuremath{\Lambda}}}_{c}^{\ifmmode\pm\else\textpm\fi{}}$-baryon production in $pp$ collisions in the general-mass variable-flavor-number scheme and compare with data from the LHCb, ALICE, and CMS collaborations. We perform a new fit of the $c\ensuremath{\rightarrow}{\mathrm{\ensuremath{\Lambda}}}_{c}^{+}$ fragmentation function combining ${e}^{+}{e}^{\ensuremath{-}}$ data from OPAL and Belle. The agreement with LHC data is slightly worse compared with a calculation using an older fragmentation function, and the tension between different determinations of ${\mathrm{\ensuremath{\Lambda}}}_{c}^{\ifmmode\pm\else\textpm\fi{}}$ production cross sections from the LHC…
The parameter identification in the Stokes system with threshold slip boundary conditions
2020
The paper is devoted to an identification of the slip bound function g in the Stokes system with threshold slip boundary conditions assuming that g depends on the tangential velocity 𝑢𝜏 . To this end the optimal control approach is used. To remove its nonsmoothness we use a regularized form of the slip conditions in the state problem. The mutual relation between solutions to the original optimization problem and the problems with regularized states is analyzed. The paper is completed by numerical experiments. peerReviewed
Numerical study of the primitive equations in the small viscosity regime
2018
In this paper we study the flow dynamics governed by the primitive equations in the small viscosity regime. We consider an initial setup consisting on two dipolar structures interacting with a no slip boundary at the bottom of the domain. The generated boundary layer is analyzed in terms of the complex singularities of the horizontal pressure gradient and of the vorticity generated at the boundary. The presence of complex singularities is correlated with the appearance of secondary recirculation regions. Two viscosity regimes, with different qualitative properties, can be distinguished in the flow dynamics.
Hyperboloidal slicing approach to quasinormal mode expansions: The Reissner-Nordström case
2018
We study quasi-normal modes of black holes, with a focus on resonant (or quasi-normal mode) expansions, in a geometric frame based on the use of conformal compactifications together with hyperboloidal foliations of spacetime. Specifically, this work extends the previous study of Schwarzschild in this geometric approach to spherically symmetric asymptotically flat black hole spacetimes, in particular Reissner-Nordstr\"om. The discussion involves, first, the non-trivial technical developments needed to address the choice of appropriate hyperboloidal slices in the extended setting as well as the generalization of the algorithm determining the coefficients in the expansion of the solution in te…
Non-smooth modelling of billiard- and superbilliard-ball collisions
2008
Abstract A description of billiard-ball collisions using a ‘discontinuous’ model is presented considering a two-step situation corresponding to the ball–ball interaction followed by ball-supporting surface interaction. It is applied to the inelastic impact of a cue ball having arbitrary pivotment and ‘English’ spins against an object ball initially at rest. This formulation provides a simplified approximation to the ‘continuous’ models of impact and considers two different regimes of impact: gross slip, and slip–stick, described in terms of coefficients of friction and restitution. As a result, the angles of scattering of the balls just after the impact (post-collision angles) and when the …
Structural quantities of quasi-two-dimensional fluids
2014
Quasi-two-dimensional fluids can be generated by confining a fluid between two parallel walls with narrow separation. Such fluids exhibit an inhomogeneous structure perpendicular to the walls due to the loss of translational symmetry. Taking the transversal degrees of freedom as a perturbation to an appropriate 2D reference fluid we provide a systematic expansion of the $m$-particle density for arbitrary $m$. To leading order in the slit width this density factorizes into the densities of the transversal and lateral degrees of freedom. Explicit expressions for the next-to-leading order terms are elaborated analytically quantifying the onset of inhomogeneity. The case $m=1$ yields the densit…
Superconductivity in one dimension
2008
Superconducting properties of metallic nanowires can be entirely different from those of bulk superconductors because of the dominating role played by thermal and quantum fluctuations of the order parameter. For superconducting wires with diameters below $ \sim 50$ nm quantum phase slippage is an important process which can yield a non-vanishing wire resistance down to very low temperatures. Further decrease of the wire diameter, for typical material parameters down to $\sim 10$ nm, results in proliferation of quantum phase slips causing a sharp crossover from superconducting to normal behavior even at T=0. A number of interesting phenomena associated both with quantum phase slips and with …
Negative magnetoresistance of ultra-narrow superconducting nanowires in the resistive state
2008
We present a phenomenological model qualitatively explaining negative magnetoresistance in quasi-one-dimensional superconducting channels in the resistive state. The model is based on the assumption that fluctuations of the order parameter (phase slips) are responsible for the finite effective resistance of a narrow superconducting wire sufficiently close to the critical temperature. Each fluctuation is accompanied by an instant formation of a quasi-normal region of the order of the non-equilibrium quasiparticle relaxation length 'pinned' to the core of the phase slip. The effective time-averaged voltage measured in experiment is a sum of two terms. First one is the conventional contributio…
E-sail test payload of the ESTCube-1 nanosatellite
2014
The scientific mission of ESTCube-1, launched in May 2013, is to measure the electric solar wind sail (E-sail) force in orbit. The experiment is planned to push forward the development of the E-sail, a propulsion method recently invented at the Finnish Meteorological Institute. The E-sail is based on extracting momentum from the solar wind plasma flow by using long thin electrically charged tethers. ESTCube-1 is equipped with one such tether, together with hardware capable of deploying and charging it. At the orbital altitude of ESTCube-1 (660–680 km) there is no solar wind present. Instead, ESTCube-1 shall observe the interaction between the charged tether and the ionospheric plasma. The E…