Stochastic Hard-Sphere Dynamics for Hydrodynamics of Non-Ideal Fluids

A novel stochastic fluid model is proposed with non-ideal structure factor consistent with compressibility, and adjustable transport coefficients. This Stochastic Hard Sphere Dynamics (SHSD) algorithm is a modification of the Direct Simulation Monte Carlo (DSMC) algorithm and has several computational advantages over event-driven hard-sphere molecular dynamics. Surprisingly, SHSD results in an equation of state and pair correlation function identical to that of a deterministic Hamiltonian system of penetrable spheres interacting with linear core pair potentials. The fluctuating hydrodynamic behavior of the SHSD fluid is verified for the Brownian motion of a nano-particle suspended in a compressible solvent.Comment: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 (LLNL-JRNL-401745). To appear in Phys. Rev. Lett. 200

A Thermodynamically-Consistent Non-Ideal Stochastic Hard-Sphere Fluid

A grid-free variant of the Direct Simulation Monte Carlo (DSMC) method is proposed, named the Isotropic DSMC (I-DSMC) method, that is suitable for simulating dense fluid flows at molecular scales. The I-DSMC algorithm eliminates all grid artifacts from the traditional DSMC algorithm; it is Galilean invariant and microscopically isotropic. The stochastic collision rules in I-DSMC are modified to yield a non-ideal structure factor that gives consistent compressibility, as first proposed in [Phys. Rev. Lett. 101:075902 (2008)]. The resulting Stochastic Hard Sphere Dynamics (SHSD) fluid is empirically shown to be thermodynamically identical to a deterministic Hamiltonian system of penetrable spheres interacting with a linear core pair potential, well-described by the hypernetted chain (HNC) approximation. We apply a stochastic Enskog kinetic theory for the SHSD fluid to obtain estimates for the transport coefficients that are in excellent agreement with particle simulations over a wide range of densities and collision rates. The fluctuating hydrodynamic behavior of the SHSD fluid is verified by comparing its dynamic structure factor against theory based on the Landau-Lifshitz Navier-Stokes equations. We also study the Brownian motion of a nano-particle suspended in an SHSD fluid and find a long-time power-law tail in its velocity autocorrelation function consistent with hydrodynamic theory and molecular dynamics calculations.Comment: 30 pages, revision adding some clarifications and a new figure. See also arXiv:0803.035

Sexualmedizin für Gynäkologen

Zusammenfassung: Die Sexualität der Frau ist ein Paradigma für das Zusammenwirken biologischer, psychologischer und sozialer Faktoren. Die wichtigsten Störungen sind Mangel an sexuellem Verlangen, Erregungsstörungen, Störungen des Orgasmus und Schmerzen bei sexueller Aktivität. Häufig kommen diese Störungen kombiniert vor. In den letzten Jahren hat sich das Wissen um die neurophysiologischen, neuroendokrinen, vasomotorischen Prozesse bei der sexuellen Reaktion enorm erweitert und zur Entwicklung neuer Medikamente geführt. Gleichzeitig haben sich die psychologischen und soziologischen Erkenntnisse entwickelt und gewandelt. Als oft erste Ansprechpartner müssen sich Gynäkologinnen und Gynäkologen kontinuierlich weiterbilden, gleichzeitig müssen sie ihre kommunikativen Fertigkeiten in diesem sensiblen Bereich schulen. Ärztliches Gespräch, Diagnostik und Therapie folgen dabei dem Modell einer biopsychosozialen Sexualmedizin, die biomedizinischen Fortschritt mit psychosozialen Interventionen verbindet, um Patientinnen bei der Entfaltung ihrer selbstbestimmten und selbstgewählten Sexualität zu helfe

Voidness and voidability in administrative law

It is proposed to investigate whether the distinction between a void and a voidable act, is a necessary incident of the law governing judicial review of administrative decisions, whether the consequences of the distinction are utilised by the Courts, and whether the distinction has a useful role to play in administrative law. The theoretical and historical basis of the distinction is first examined with the conclusion that void and voidable decisions are a necessary result of a system of review based upon the ultra vires doctrine. The notion of jurisdiction is examined to ascertain whether there is any general formula with which to distinguish between decisions producing nullity and those resulting in a voidable decision. It is concluded that such a formula is undesirable in principle and can not in the light of existing authority be produced. The various reviewable defects are then analysed to determine whether the Courts regard them as void or voidable. There is considerable inconsistency in the cases, but it is reasonably clear that some procedural defects, breach of natural justice, and serious abuse of discretion are jurisdictional and produce nullity. As a result of this an investigation of the various consequences of the distinction in connection with remedies, leous standi, estoppel, and privative clauses leads to the conclusion that the Courts do not consistently apply the logical consequences of nullity, and indeed that to do so would produce inconvienience. However, in the field of actions in tort and privative clauses the distinction is consistently relied upon. Finally voidable decisions are examined to determine whether a doctrine of retroactivity operates with the conclusion that it does not. In conclusion the technical difficulties arising from the existing system of review based upon the notion of jurisdiction are criticised, and a broader basis for judicial review is proposed which would involve the ultra vires doctrine and therefore the void voidable distinction having only a subordinate role

Phase transition in inelastic disks

This letter investigates the molecular dynamics of inelastic disks without external forcing. By introducing a new observation frame with a rescaled time, we observe the virtual steady states converted from asymptotic energy dissipation processes. System behavior in the thermodynamic limit is carefully investigated. It is found that a phase transition with symmetry breaking occurs when the magnitude of dissipation is greater than a critical value.Comment: 9 pages, 6 figure