Rainer Gerling

Munich University of Applied Sciences | HM · Department of Computer Science and Mathematics

Zusammenfassung Seit 2015 gibt es im Rahmen der IT-Sicherheitsgesetzgebung für den KRITIS-Bereich IT- Sicherheitsvorgaben für große Krankenhäuser. 2019 wurde der Regelungsrahmen für kassenärztliche und kassenzahnärztliche Praxen geschaffen (§ 75b SGB V). Der noch fehlende Regelungsbereich für kleine Krankenhäuser wurde 2020 mit dem § 75c SGB V gesc...

Zusammenfassung Der Beitrag analysiert die Praxis einiger Datenschutzaufsichtsbehörden bei der Bewertung von Videokonferenzlösungen vor dem Hintergrund des Stands der Technik. Die Informationspraxis der Datenschutzaufsichtsbehörden wird anschließend hinsichtlich der rechtlichen Auswirkungen auf Anbieter und Verantwortliche bewertet.

Political elections are still conducted using paper ballots. In an age when we use the internet to find information and do our shopping, use apps to control home heating and even use online functions for ID cards, this is quite astounding. Wouldn’t it be much easier and more convenient to vote for our politicians from our home computers or smartpho...

HTTPS is the standard for confidential and integrity-protected communication on the Web. However, it authenticates the server, not its content. We present WebTrust, the first comprehensive authenticity and integrity framework that allows on-the-fly verification of static, dynamic, and real-time streamed Web content from untrusted servers. Our frame...

Das sicherere, geschlossene E-Mail-System De-Mail ist eigentlich nur ein konsequenter Schritt, den Unternehmen schon vor Jahren gemacht haben, nachdem zahlreiche PKI-Projekte gescheitert waren: Nutzer sahen entweder die Notwendigkeit dafür nicht ein („Wer interessiert sich schon für meine E-Mail?“) oder verstanden die Schutzkonzepte nicht. Mit „E-M...

Der Entwurf der Europäischen Datenschutz-Grundverordnung fordert in Artikel 17 ein „Recht auf Vergessenwerden“. Dies ist als organisatorische Regel sicherlich sinnvoll; es stellt sich aber sofort die Frage, inwieweit so etwas auch technisch realisierbar ist. Die existierenden Lösungen und Ansätze werden bewertet und im Licht der Vorgaben der Verord...

Datenschutz und Forschungsfreiheit scheinen sich in manchen Situationen zu widersprechen. Die ethische Verantwortung des Wissenschaftlers muss für einen fairen Ausgleich zwischen den Grundrechten sorgen. Der Gesetzgeber hat dem Wissenschaftler aber Grenzen gesetzt. Im internationalen Wettbewerb entstehen zusätzliche Probleme.

The zero-field parallel and perpendicular susceptibility and the zero-field specific heat of the quantum easy-plane S=1 Heisenberg spin chains are calculated numerically and applied to TMNB, TMNC and CsNiF3. New values of the model parameters are estimated from fitting procedures. As to CsNiF3, the in-plane specific heat, the field-dependent magnet...

Aus vielen Kommunikationsbeziehungen ist E-Mail wegen seiner Einfachheit und Schnelligkeit nicht mehr wegzudenken. Aber es gibt auch noch Probleme bei der Einführung und Nutzung der E-Mail als sicheres Kommunikationsmittel. Die Einfuhrung eines E-Mail Systems, das allen organisatorischen und technischen Anforderungen gerecht wird, erfordert einiges...

Kryptographie galt viele Jahre als eine Domäne für Geheimdienste und auch heute kämpft man beim Einsatz kryptographische Verfahren gegen das Vorurteil, „dies seien Relikte des Kalten Krieges und nicht mehr zeitgemäß“.

Wer heute ein Rechenzentrum betreibt, sieht sich einer Vielzahl von rechtlichen Problemen aus nahezu allen Rechtsbereichen gegenüber. Dazu kommt als besondere juristische Delikatesse die Problematik des Internets, das sich aufgrund seiner teilweise nahezu chaotischen internationalen Strukturen einer Beurteilung nach nationalem Recht fast schon entz...

The use of and the communication via computer becomes widespread. Along with this more and more confidential data are stored in computers or send through computer networks. The unauthorized access to the confidential data has to be restricted. The standard to do so is the use of modern cryptographic tools. A short introduction to cryptography is gi...

A scaling theory for the parallel efficiency of simulations on MIMD computers is presented. It is successfully applied to the performance results recently reported by Kohring and Stauffer for different algorithms on an Intel i860 Hypercube. The discrepancies between the measured scaling exponents and our predictions are resolved within the framewor...

We investigate the performance of two-dimensional cellular automata simulations on two parallel computers of the message-passing type, namely a small Transputer system and one SUPRENUM-cluster. The timing results can be fitted with a simple modelling function with parameters directly connected to properties of the algorithm and the computer system....

A knowledge of the density of states () of a many particle system ( is the energy per particle) contains the complete information about its thermal behaviour. In this paper it will be demonstrated that () can very efficiently and precisely be determined by a Monte Carlo calculation in an ensemble where the system of interest is coupled to another s...

The classical one-dimensional XY model in a symmetry-breaking Gaussian-distributed random magnetic field was studied using an ultrafast, vectorized spin-dynamics program on a Cray Y-MP. We calculated the time- and space-displaced spin-spin correlation functions, which was then Fourier-transformed to get the neutron-scattering law S(q,ω). We see a c...

A Comment on the Letter by de Alcantara Bonfim, G. Reiter, Phys. Rev. Lett. 69, 367 (1992).

Histogram techniques have been used to study phase transitions in the simple cubic Ising model with competing nearest- and next-nearest-neighbor interactions at a point in the phase diagram where the ground state is infinitely degenerate in the thermodynamic limit.

The time dependent behavior of the classical, ferromagnetic xy-chain and the anisotropic Heisenberg chain in a symmetry breaking magnetic field was studied using a very fast, vectorized spin-dynamics method. The equations of motion were integrated using starting configurations determined by Monte-Carlo simulations. By calculating spin-spin correlat...

Using a sophisticated vectorised spin-dynamics simulation algorithm, we have studied magnetic excitations in the one-dimensional xy-model with antiferromagnetic nearest neighbor exchange J and a magnetic field h in the x-direction. We have followed the time development out to time t=100J-1 for temperatures as low as kBT=0.1J and fields as large as...

Dynamics of the ferromagnetic easy-plane Heisenberg chain has been simulated by a standard Monte Carlo algorithm and the accurate numerical integration of the equations of motion for the spin variables. The dynamic structure factors S(q, omega) have been calculated for a wide range of field and temperatures and interpreted in terms of spin-wave and...

The numerical finite-size technique has been applied to study thermodynamic properties of the S = 1 quasi-one-dimensional magnets CsNiF3, (CH3)4NNiBr3 (TMNB), (CH3)4NNiCl3 (TMNC) and CsNiCl3, the latter showing the Haldane gap. The length of chains has been extended up to N ≤ 8 and the successful fitting procedure has been performed to match the pa...

We present the first high resolution spin dynamics simulation of critical dynamics in the classical, two-dimensional XY-model. Using square lattices as large as 204 × 204 with periodic boundaries, we integrate coupled equations of motion and determine the scattering function S(q, ω). At the critical temperature we find a rich structure which is not...

We present a universal scaling law for all geometrically parallelized computer simulation algorithms. For algorithms with local interaction laws we calculate the scaling exponents for zero and infinite lattice size. The scaling is tested on local (cellular automata, Metropolis Ising) as well as cluster (Swendsen-Wang) algorithms. The practical aspe...

``Dissident'' sites in random Boolean automata always differ from all their four nearest neighbors. We check how their number decreases if for each such site the rule which it obeys is inverted in regular intervals. We updated 0.9 sites per nanosecond on one NEC-SX3 processor; for simple one-dimensional exclusive-or automata, we updated 14 sites pe...

Cellular automata are studied on a variety of different lattices. The results for the classification and for damage spreading are reported. Details of the algorithm and the implementation on different computers are also presented.

An ultrafast, vectorized spin-dynamics method is used to study the time-dependent properties of classical XY and Heisenberg spin chains at infinite temperature. The decay of the energy-energy and spin-spin correlation functions is oscillatory for short times and at long times is consistent with classical diffusion, although the approach to the asym...

Cellular automata with 2, 3, and 4 states on a one-dimensional lattice are classified according to their fixed points and periods. Also the spreading of damage in these systems is studied.

We have investigated the time-dependent behavior of the classical XY chain in a symmetry-breaking anisotropy field using an ultrafast spin-dynamics method in which we integrate the equation of motion with equilibrium spin configurations determined by Monte Carlo simulations. All three polarizations of the scattering function S(q,ω) were determined...

We studied a simple model for translational-rotational coupling. Our system is made up from four harmonic oscillators driven by a stochastic force and hindered by friction, which move on the four sides of a square. In the center of the square is a rotating dumbbell molecule, which is coupled to the four oscillators via an attractiver −1 potential....

The time-dependent behavior of the classical, ferromagnetic xy chain in a symmetry-breaking magnetic field was studied using a very fast, vectorized spin-dynamics method. The equations of motion were integrated using starting configurations determined by Monte Carlo simulations. By calculating spin-spin correlation functions and taking space-time F...

Cellular automata on a two-dimensional triangular and honeycomb lattice are classified according to their fixed points and periods. The results are compared with other lattices in one of three dimensions. We also compare the totalistic rules for all mentioned lattices. Present and permanent address: Institut für Theoretische Physik I der Universitä...

Cellular automata on a simple cubic lattice are classified according to their fixed points and periods. The computer simulations show drastic differences with respect to two dimensions. Present and permanent address: Institut für Theoretische Physik Uder Universität Erlangen-Nürnberg, Staudtstrasse 7, D-8520 Erlangen, Fed. Rep. Germany.

The application of the Langevin-formalism for the study of rotating molecules is demonstrated with three examples: The rotational motion of the NH4 tetrahedron in the molecular crystal NH4Cl. A numerical solution of the nonlinear Langevin equation. A simple model for translational-rotational coupling.

A Comment on the Letter by G. Müller, Phys. Rev. Lett. 60, 2785 (1988).

A variant of the quantum transfer-matrix method is used to obtain numerically accurate results for the specific heat of an easy-plane spin chain with an in-plane field, corresponding to the ferromagnetic compound CHAB. They are contrasted with predictions of the classical sine-Gordon approximation for the chain and with experimental data.

We have studied the time-dependent behavior of the classical XY chain in a symmetry breaking magnetic field using an ultrafast spin-dynamics method in which we integrate the equations of motion using starting configurations determined by Monte Carlo simulations. We calculated the three polarizations of S(q,ω) separately for temperatures from 0.1 to...

We present extensive computer-simulation results for the static and dynamic properties of the one-dimensional classical XY model in a symmetry-breaking magnetic field. In-plane solitons are directly observed and their density is determined as a function of field and temperature. The bulk properties and the scattering function S(q,omega) are also de...

The interest in one-dimensional magnetic systems has been great over the years. The fact that this type of systems exhibit soliton or soliton-like features has launched quite some activities, experimentally as well as theoretically. The field is shortly summarized before the results of a numerical study of the one-dimensional classical xy-model in...

Thermal properties of the one-dimensional classical XY-model in a symmetry-breaking field are studied by using the transfer-kernel method. The results complete earlier data from Monte-Carlo simulations.

Over the past decade, there has been increasing interest in the study of solitons in magnetic chains. Motivation for this interest has come from the beautiful neutron scattering studies of CSNiF3 by Steiner and Kjems [1] and from the theoretical work by Mikeska and co-workers [2] who mapped the anisotropic Heisenberg chain onto the sine-Gordon equa...

In the last decade the interest in one-dimensional magnetic systems has been great. The reason for this is two-fold: (i) there exist beautiful experimental results [1–6] for quasi one-dimensional systems and (ii) these systems are theoretically much easier to treat than the corresponding two- or three-dimensional models.

The classical one-dimensional xy-model is studied using Monte Carlo and spin-dynamic methods. We demonstrate the existence of solitons in both ferromagnetic and antiferromagnetic chains, and compare their behavior with existing theory.

An important sampling Monte Carlo method is used to study the classical, antiferromagnetic, XY chain in a symmetry breaking uniform magnetic field. From equilibrium configurations we extract values for the bulk properties as well as explicit pictures showing individual spin directions. An analysis of the angles which the spin makes with the field s...

Using Monte Carlo and spin dynamics methods we present evidence for the existence of solitons in the classical one dimensional xy-chain. From the simulation results we calculated the specific heat to see the contribution of the solitons. Using special computer programs we were able to see the moving solitons directly and to determine the soliton ve...

A one-dimensional Langevin Equation in which the friction term and the stochastic force term depend nonlinearly on the velocity is presented. Assuming that the Maxwell distribution is the stationary solution of the Fokker Planck Equation (which is equivalent to the nonlinear Langevin Equation) we derive a generalization of the Fluctuation Dissipati...

It has been known For some time [1–4] that the classical XY-model in one and two dimensions shows behavior which is governed by nonlinear excitations.

We present results for the static and dynamic behavior of a one-dimensional classical XY chain. Equilibrium configurations are produced by an importance-sampling Monte Carlo method. Static properties are evaluated from these data and a spin-dynamics method is then used to evaluate time-displaced correlation functions and to calculate the scattering...

The ammonium tetrahedron in NH+4Cl− experiences an orientational potential of considerable strength. Changes of orientation occur through thermally activated jumps across the potential barriers (rotational jumps). Whereas the experimentally determined overall jump rate is in general agreement with deductions from model potentials, the detailed jump...

The rotational motion of a linear molecule in a potential of cubic symmetry is treated in the framework of the Langevin equation. The corresponding Langevin equation is solved numerically. From these numerical data, time-dependent correlation functions are extracted and compared with the results of other models. It is found that the harmonic approx...

Results are presented for the static and dynamic behavior of a classical XY‐chain in a magnetic field. Equilibrium configurations were produced by an importance sampling Monte Carlo method.Static properties are evaluated from these data and a spin‐dynamics method is then used to evaluate time displaced correlation functions. The energy‐energy corre...

The problem of a uniaxial rotator in anN-fold potential is described in the framework of the Langevin model. In this model the molecule is driven by a stochastic torque and hindered by a friction term. The resulting equation of motion is solved by numerical methods and in some limiting cases an analytic solution is given, too. Symmetry adapted auto...

Globular molecules in dense gases, liquids, and orientationally disordered crystals experience an incessant fluctuating torque of rather weak magnitude. In gases and liquids the fluctuating torque perturbs the otherwise free rotational motion which becomes diffusive. We treat the rotational diffusion within the Langevin model where the molecules ar...