Search results for "quantitative"
showing 10 items of 2409 documents
A comment on “Research on the nonlinear pulse propagation by numerical analysis” by Li and Yin [Optik 12 (13) (2011) 1195–1200]
2012
In the article entitled "Research on the nonlinear pulse propagation by numerical analysis" , Li Li and Aihan Yin summarize the key elements affecting the nonlinear propagation of an optical pulse in an optical fiber. We comment these results.
Quantitative Determination of Renal 99mTc-MAG3 Clearance. A Comparison of Results Acquired Simultaneously in Whole Body Geometry and with a Gamma Cam…
1997
289 patients were simultaneously investigated with a partially shielded whole body counter (Oberhausen) and in camera technique to correlate the values of the MAG3-clearance. Good correlation was found for the often used times schedules of taking blood samples. Late blood samples increase high clearance values in both methods slighly. The shape of the ROI has no influence using camera technique. We conclude, that camera technique can replace the Oberhausen method with a partially shielded whole body counter.
Periodic Motion for an Imperfect Solar Sail Near an Asteroid
2014
In this paper we consider the Hill 3-body problem with the extra effect of the solar radiation pressure as a model for the motion of a solar sail close to an asteroid. To model the sail’s acceleration, we include both reflectivity and absorption of the sail’s material. We describe the most relevant dynamical properties of the system for different reflectivity and absorption coefficients as well as different fixed sail orientations. We show families of periodic orbits, describe how they relate to the parameters of the sail and discuss their stability.
Suppression of noise in FitzHugh–Nagumo model driven by a strong periodic signal
2005
Abstract The response time of a neuron in the presence of a strong periodic driving in the stochastic FitzHugh–Nagumo model is investigated. We analyze two cases: (i) the variable that corresponds to membrane potential is subjected to fluctuations, and (ii) the recovery variable associated with the refractory properties of a neuron is noisy. The influence of noise sources on the delay of the response of a neuron is analyzed. In both cases we observe a resonant activation-like phenomenon and suppression of noise: the negative effect of fluctuations on the process of spike generation is minimal near the resonance region. The phenomenon of noise enhanced stability is also observed in both case…
Synchronized rotation in swarms of magnetotactic bacteria.
2017
Self-organizing behavior has been widely reported in both natural and artificial systems, typically distinguishing between temporal organization (synchronization) and spatial organization (swarming). Swarming has been experimentally observed in systems of magnetotactic bacteria under the action of external magnetic fields. Here we present a model of ensembles of magnetotactic bacteria in which hydrodynamic interactions lead to temporal synchronization in addition to the swarming. After a period of stabilization during which the bacteria form a quasiregular hexagonal lattice structure, the entire swarm begins to rotate in a direction opposite to the direction of the rotation of the magnetic …
Anomalous Fluctuations of Nematic Order in Solutions of Semiflexible Polymers
2016
The nematic ordering in semiflexible polymers with contour length $L$ exceeding their persistence length $\ell_p$ is described by a confinement of the polymers in a cylinder of radius $r_{eff}$ much larger than the radius $r_\rho$, expected from the respective concentration of the solution. Large scale Molecular Dynamics simulations combined with Density Functional Theory are used to locate the Isotropic-Nematic ($I-N$)-transition and to validate this cylindrical confinement. Anomalous fluctuations, due to chain deflections from neighboring chains in the nematic phase are proposed. Considering deflections as collective excitations in the nematically ordered phase of semiflexible polymers el…
Lepton asymmetries and primordial hypermagnetic helicity evolution
2012
The hypermagnetic helicity density at the electroweak phase transition (EWPT) exceeds many orders of magnitude the galactic magnetic helicity density. Together with previous magnetic helicity evolution calculations after the EWPT and hypermagnetic helicity conversion to the magnetic one at the EWPT, the present calculation completes the description of the evolution of this important topological feature of cosmological magnetic fields. It suggests that if the magnetic field seeding the galactic dynamo has a primordial origin, it should be substantially helical. This should be taken into account in scenarios of galactic magnetic field evolution with a cosmological seed.
Perturbations of the classical Lotka-Volterra system by behavioral sequences
1995
The complexity and the variability of parameters occurring in ecological dynamical systems imply a large number of equations.
A theory for long-memory in supply and demand
2004
Recent empirical studies have demonstrated long-memory in the signs of orders to buy or sell in financial markets [2, 19]. We show how this can be caused by delays in market clearing. Under the common practice of order splitting, large orders are broken up into pieces and executed incrementally. If the size of such large orders is power law distributed, this gives rise to power law decaying autocorrelations in the signs of executed orders. More specifically, we show that if the cumulative distribution of large orders of volume v is proportional to v to the power -alpha and the size of executed orders is constant, the autocorrelation of order signs as a function of the lag tau is asymptotica…
EnCurv: Simple Technique of Maintaining Global Membrane Curvature in Molecular Dynamics Simulations.
2021
The EnCurv method for maintaining membrane curvature in molecular dynamics simulations is introduced. The method allows maintaining any desired curvature in a sector of lipid membrane bent in a single plane without adding any unphysical interactions into the system and without restrictions on lateral and transversal lipid diffusion and distribution. The current implementation is limited to the membranes curved in a single plane but generalization to arbitrary curvature and membrane topology is possible. The method is simple, easy to implement, and scales linearly with the system size. EnCurv is agnostic to the force field, simulation parameters, and membrane composition. The proof of princi…