New simple explicit solutions of perfect fluid hydrodynamics and phase-space evolution

New exact solutions of relativistic perfect fluid hydrodynamics are described, including the first family of exact rotating solutions. The method used to search for them is an investigation of the relativistic hydrodynamical equations and the collisionless Boltzmann equation. Possible connections to the evolution of hot and dense partonic matter in heavy-ion collisions is discussed.Comment: 7 pages, 2 figures, two column format. First version substantially rewritten, typos corrected. Results unchange

Anomalous diffusion of pions at RHIC

After pointing out the difference between normal and anomalous diffusion, we consider a hadron resonance cascade (HRC) model simulation for particle emission at RHIC and point out, that rescattering in an expanding hadron resonance gas leads to a heavy tail in the source distribution. The results are compared to recent PHENIX measurements of the tail of the particle emitting source in Au+Au collisions at RHIC. In this context, we show, how can one distinguish experimentally the anomalous diffusion of hadrons from a second order QCD phase transition.Comment: 12 pages, 26 figures. Presented by T. Csorgo at the 2nd Workshop on Particle Femtoscopy and Correlations - WPCF in Sao Paulo, sept 2006. Brazilian Journal of Physics in press, minor misprints fixe

Utilizing Community Resources to Reduce the Presence of Type 2 Diabetes in Rural Youth

The purpose of this study was to implement a program designed to promote diabetes prevention activities among preadolescents in a rural southern setting using a day camp intervention. Participants in the study were eleven youth from a rural Alabama county who participated in a week-long half-day camp administered by local and community volunteers. Change scores were used to compare pre- to post- to follow-up measures for camp participant responses. Program results consistently demonstrated that the day camp was theoretically sound and that program activities positively impacted behavioral antecedents. This study demonstrated the feasibility of conducting a diabetes prevention day camp in a rural environment. Insights from this intervention can assist planners in rural environments to tailor similar initiatives in rural settings. Given the complicated nature of behavior change, a day camp approach of this length does not modify the behaviors of participants. Behavior changes may take considerably longer to initiate

Oscillator Models of the Solar Cycle and the Waldmeier Effect

We study the behaviour of the van der Pol oscillator when either its damping parameter $\mu$ or its nonlinearity parameter $\xi$ is subject to additive or multiplicative random noise. Assuming various power law exponents for the relation between the oscillating variable and the sunspot number, for each case we map the parameter plane defined by the amplitude and the correlation time of the perturbation and mark the parameter regime where the sunspot number displays solar-like behaviour. Solar-like behaviour is defined here as a good correlation between the rise rate and cycle amplitude {\it and} the lack of a good correlation between the decay rate and amplitude, together with significant (\ga 10\,%) r.m.s. variation in cycle lengths and cycle amplitudes. It is found that perturbing $\mu$ alone the perturbed van der Pol oscillator does not show solar-like behaviour. When the perturbed variable is $\xi$, solar-like behaviour is displayed for perturbations with a correlation time of about 3--4 years and significant amplitude. Such studies may provide useful constraints on solar dynamo models and their parameters.Comment: 4 pages, 2 figure

A New Family of Simple Solutions of Perfect Fluid Hydrodynamics

A new class of accelerating, exact and explicit solutions of relativistic hydrodynamics is found - more than 50 years after the previous similar result, the Landau-Khalatnikov solution. Surprisingly, the new solutions have a simple form, that generalizes the renowned, but accelerationless, Hwa-Bjorken solution. These new solutions take into account the work done by the fluid elements on each other, and work not only in one temporal and one spatial dimensions, but also in arbitrary number of spatial dimensions. They are applied here for an advanced estimation of initial energy density and life-time of the reaction in ultra-relativistic heavy ion collisions.Comment: 10 pages, 5 figures. EOS is generalized to include a bag constant, clarity of the presentation is improved and a misprinted label is corrected in Fig. 2.

Similar final states from different initial states using new exact solutions of relativistic hydrodynamics

We present exact, analytic and simple solutions of relativistic perfect fluid hydrodynamics. The solutions allow us to calculate the rapidity distribution of the particles produced at the freeze-out, and fit them to the measured rapidity distribution data. We also give an advanced estimation of the energy density reached in heavy ion collisions, and an improved estimation of the life-time of the reaction.Comment: This article is a written-up version of the talk given by M. Csanad on the Zimanyi '75 Memorial Workshop held in Budapest, June 200