The fate of the Mach cone in covariant transport theory

An intriguing potential signature of hydrodynamic behavior in relativistic A+A reactions at Relativistic Heavy Ion Collider (RHIC) energies is conical flow induced by fast supersonic particles traversing the hot and dense medium. Here I present first results on the evolution of Mach shocks in 2->2 covariant transport theory, in a static uniform medium.Comment: Presentation at CIPANP 2009 (Tenth Conference on the Intersections of Particle and Nuclear Physics), May 26-31, 2009, Torrey Pines, California, US

Multimode pulsation of the ZZ Ceti star GD 154

We present the results of a comparative period search on different time-scales and modelling of the ZZ Ceti (DAV) star GD 154. We determined six frequencies as normal modes and four rotational doublets around the ones having the largest amplitude. Two normal modes at 807.62 and 861.56 microHz have never been reported before. A rigorous test revealed remarkable intrinsic amplitude variability of frequencies at 839.14 and 861.56 microHz over a 50 d time-scale. In addition, the multimode pulsation changed to monoperiodic pulsation with an 843.15 microHz dominant frequency at the end of the observing run. The 2.76 microHz average rotational split detected led to a determination of a 2.1 d rotational period for GD 154. We searched for model solutions with effective temperatures and log g close to the spectroscopically determined ones. The best-fitting models resulting from the grid search have M_H between 6.3 x 10^-5 and 6.3 x 10^-7 M*, which means thicker hydrogen layer than the previous studies suggested. Our investigations show that mode trapping does not necessarily operate in all of the observed modes and the best candidate for a trapped mode is at 2484 microHz.Comment: 11 pages, 11 figures, accepted for publication in MNRA

Freeze out in narrow and wide layers

The freeze out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze out distributions. The dependence of the resulting distribution on the thickness of the layer is presented and discussed for a space-like freeze out scenario.Comment: Minor corrections to improve the presentation. 4 pages, 2 figures, to appear in the Proceedings of "Quark Matter 2005", August 4-9, 2005, Budapest, Hungar

Covariant kinetic freeze out description through a finite space-time layer

We develop and analyze a covariant FO probability valid for a finite space-time layer.Comment: Proceedings of "Quark Matter 2005", 4 pages, 3 figures, with correction

Consumer Purchasing Behaviors and Attitudes toward Shopping at Public Markets

This paper identifies and empirically evaluates factors that explain the variations in consumers’ attitudes toward shopping at farmers markets in general and public markets in particular. The analysis draws on data from a telephone survey conducted in Jefferson County, Alabama. Logit model results point to several factors that seem to be strongly correlated with consumer purchasing behaviors and attitudes toward shopping at public markets, including income, education, age of household head, household size, and price and quality of produce. The insights gained from the study should help farmers increase the profitability of their operations and improve the likelihood that they will continue farming.Consumer/Household Economics,

Jet-like correlations between Forward- and Mid- rapidity in p+p, d+Au and Au+Au collisions from STAR at 200 GeV

In this proceedings we present STAR measurements of two particle azimuthal correlations between trigger particles at mid-rapidity ($|\eta|<$ 1) and associated particles at forward rapidities (2.7 $<|\eta|<$ 3.9) in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV. Two particle azimuthal correlations between a mid-rapidity trigger particle and forward-rapidity associated particles preferably probe large-x quarks scattered off small-x gluons in RHIC collisions. Comparison of the separate d- and Au-side measurements in d+Au collisions may potentially probe gluon saturation and the presence of Color Glass Condensate. In Au+Au collisions quark energy loss can be probed at large rapidities, which may be different from gluon energy loss measured at mid-rapidity.Comment: Quark Matter 06 Conference proceedings, submitted to Journal of Phys.

The 3rd Flow Component as a QGP Signal

Earlier fluid dynamical calculations with QGP show a softening of the directed flow while with hadronic matter this effect is absent. On the other hand, we indicated that a third flow component shows up in the reaction plane as an enhanced emission, which is orthogonal to the directed flow. This is not shadowed by the deflected projectile and target, and shows up at measurable rapidities, $y_cm = 1-2$. To study the formation of this effect initial stages of relativistic heavy ion collisions are studied. An effective string rope model is presented for heavy ion collisions at RHIC energies. Our model takes into account baryon recoil for both target and projectile, arising from the acceleration of partons in an effective field. The typical field strength (string tension) for RHIC energies is about 5-12 GeV/fm, what allows us to talk about "string ropes". The results show that QGP forms a tilted disk, such that the direction of the largest pressure gradient stays in the reaction plane, but deviates from both the beam and the usual transverse flow directions. The produced initial state can be used as an initial condition for further hydrodynamical calculations. Such initial conditions lead to the creation of third flow component. Recent $v_1$ measurements are promising that this effect can be used as a diagnostic tool of the QGP

Non-parabolicity of the conduction band of wurtzite GaN

Using cyclotron resonance, we measure the effective mass, $m$*, of electrons in AlGaN/GaN heterostructures with densities, $n_{2D}\sim 1-6\times10^{12}$cm$^{-2}$. From our extensive data, we extrapolate a band edge mass of $(0.208\pm0.002) m_e$. By comparing our $m$* data with the results of a multi-band \textbf{k.p} calculation we infer that the effect of remote bands is essential in explaining the observed conduction band non-parabolicity (NP). Our calculation of polaron mass corrections -- including finite width and screening - suggests those to be negligible. It implies that the behavior of $m*(n_{2D})$ can be understood solely in terms of NP. Finally, using our NP and polaron corrections, we are able to reduce the large scatter in the published band edge mass values