Planet--planet scattering in circumstellar gas disks

Hydrodynamical simulations of two giant planets embedded in a gaseous disk have shown that in case of a smooth convergent migration they end up trapped into a mean motion resonance. These findings have led to the conviction that the onset of dynamical instability causing close encounters between the planets can occur only after the dissipation of the gas when the eccentricity damping is over. We show that a system of three giant planets may undergo planet-planet scattering when the gaseous disk, with density values comparable to that of the Minimum Mass Solar Nebula, is still interacting with the planets. The hydrodynamical code FARGO--2D--1D is used to model the evolution ofthe disk and planets, modified to properly handle close encounters between the massive bodies. Our simulations predict a variety of different outcomes of the scattering phase which includes orbital exchange, planet merging and scattering of a planet in a hyperbolic orbit. This implies thatthe final fate of a multiplanet system under the action of the disk torques is not necessarily a packed resonant configuration.Comment: Astronomy and Astrophysics Letters, in pres

Scientific Knowledge of the Human Side of Information Security as a Basis for Sustainable Trainings in Organizational Practices

Comprehensive digitization leads to new chal-lenges because of cybercrime and related security countermeasures. There is no doubt that this will fundamentally affect our lives and is leading to an increase in the importance of information security (IS). However, technology solutions alone are not sufficient to ensure IS countermeasures. The human side of security is important to protect organizational assets like user information and systems. The paper illustrates these relationships in terms of information security awareness (ISA), examining its goals and the factors influencing it through the systematic analysis and review of scientific literature and the transfer of scientific knowledge for practical purposes. We reviewed the publications of leading academic journals in the field of IS over the past decade

Simple heuristics for the assembly line worker assignment and balancing problem

We propose simple heuristics for the assembly line worker assignment and balancing problem. This problem typically occurs in assembly lines in sheltered work centers for the disabled. Different from the classical simple assembly line balancing problem, the task execution times vary according to the assigned worker. We develop a constructive heuristic framework based on task and worker priority rules defining the order in which the tasks and workers should be assigned to the workstations. We present a number of such rules and compare their performance across three possible uses: as a stand-alone method, as an initial solution generator for meta-heuristics, and as a decoder for a hybrid genetic algorithm. Our results show that the heuristics are fast, they obtain good results as a stand-alone method and are efficient when used as a initial solution generator or as a solution decoder within more elaborate approaches.Comment: 18 pages, 1 figur

Triaxiality and the determination of the cubic shape parameter K3 from five observables

The absolute and the relative quadrupole shape invariants q3 and K3 provide a model independent measure of triaxiality for beta-rigid nuclei. We will show that one can obtain q3 and K3 from a small number of observables. The approximations which are made will be shown to hold within a few percent both in the rigid triaxial rotor model and the interacting boson model. The shape parameter K3 is given for an exemplary set of nuclei and is translated into effective values of the geometrical deformation parameters beta and gamma.Comment: 16 pages, 4 figure

System for measuring passenger reaction to transportation-vehicle vibration

Equipment is capable of measuring frequencies from 0 to 50 Hz and is portable, light, inexpensive, and easily adaptable to field operations. System could be used in situations where it is necessary to record simultaneously subject response to other types of physical measurement or stimuli, such as temperature, noise, or pressure

Quantum theory of impact ionization in coherent high-field semiconductor transport

Generation of carriers in semiconductors by impact ionization is studied under the influence of a constant, arbibrarily high electric field. Using the density-matrix approach a system of equations for the coherent dynamics of electrons and holes in the presence of impact ionization and Auger recombination is derived, which extends the semiconductor Bloch equations by the inclusion of impact-ionization density-correlation functions as additional dynamic variables. From these equations we recover the pure (Zener) and the photon-induced (Franz-Keldysh) carrier tunneling rate and derive an expression for the field-assisted impact-ionization scattering rate. Different levels of approximation of the kinetic equations are discussed. It is shown that in contrast to the semiclassical treatment in the presence of an electric field, a fixed impact-ionization threshold does no longer exist, and the impact-ionization scattering rate is drastically enhanced around the semiclassical threshold by the intracollisional field effect. The close connection of field-assisted impact ionization to the Franz-Keldysh effect is emphasized