Theoretical Overview on (Hidden) Charm in High-Energy Heavy-Ion Collisions

Recent developments in the theoretical evaluation of charmonium production in ultrarelativistic heavy-ion collisions (URHIC's) are discussed. In particular, the consequences of equilibrium properties of open and hidden charm states -- accessible, {\it e.g.}, in QCD lattice gauge calculations -- are assessed. These include abundances as well as formation and dissociation rates of charmonia in both hadronic and quark-gluon matter.Comment: Invited Talk at 7. Int. Conf. on Strangeness in Quark Matter (Atlantic Beach, NC, USA, 12.-17.03.03); 10 pages LaTeX including 11 Figures and iop style files; v3: Section 3.4 (Continuity) revise

Two-Component Approach to J/ΨJ/\Psi Production in High-Energy Heavy-Ion Collisions

The production of charmonia in ultrarelativistic heavy-ion collisions is investigated including two sources. These are a primordial contribution coupled with various phases of dissociation, and a statistical coalescence of $c$ and $\bar{c}$ quarks at the hadronization phase transition. Within a schematic fireball evolution, SPS data on $J/\Psi$ production can be reasonably well reproduced. Remaining discrepancies in the $\Psi'/\Psi$ ratio are discussed. Predictions for the $J/\Psi$ centrality dependence at RHIC energies are confronted with first data from PHENIX. The pertinent excitation function of the $N_{J/\Psi}/N_{c\bar{c}}$ ratio exhibits a characteristic minimum structure signaling the transition from the standard $J/\Psi$ suppression scenario (SPS) to predominantly statistical production (RHIC).Comment: 4 pages (incl. 4 postscript figures); v2: Typos corrected; uses espcrc1.sty. Talk given at Quark Matter 2002, Nantes, July 18-24, 2002, to appear in the proceedings in Nucl. Phys.

Thermal versus Direct J/ΨJ/\Psi Production in Ultrarelativistic Heavy-Ion Collisions

The production of $J/\Psi$ mesons in central collisions of heavy nuclei is investigated as a function of collision energy. Two contributions are considered simultaneously: early (hard) production coupled with subsequent suppression in a Quark-Gluon Plasma, as well as thermal recombination of primordially produced $c$ and $\bar c$ quarks at the hadronization transition. Whereas the former still constitutes the major fraction of the observed $J/\Psi$ abundance at SpS energies, the latter dominates the yield at RHIC. The resulting excitation function for the number of $J/\Psi$'s over open charm pairs exhibits nontrivial structure around $\sqrt{s} \simeq 30$ AGeV, evolving into a significant rise towards maximal RHIC energy. We study this feature within different (thermal) scenarios for $J/\Psi$ suppression, including parton-induced quasifree destruction as a novel mechanism.Comment: 6 pages ReVTeX, including 4 eps-figures; Revised version accepted for publication in Phys. Lett.

Reliability studies of integrated modular engine system designs

A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented

Characterization of aluminum/RP-1 gel propellant properties

Research efforts are being conducted by the NASA Lewis Research Center to formulate and characterize the properties of Al/RP-1 and RP-1 gelled propellants for rocket propulsion systems. Twenty four different compositions of gelled fuels were formulated with 5 and 16 micron, atomized aluminum powder in RP-1. The total solids concentration in the propellant varied from 5 to 60 wt percent. Tests were conducted to evaluate the stability and rheological characteristics of the fuels. Physical separation of the solids occurred in fuels with less than 50 wt percent solids concentration. The rheological characteristics of the Al/RP-1 fuels varied with solids concentration. Both thixotropic and rheopectic gel behavior were observed. The unmetallized RP-1 gels, which were formulated by a different technique than the Al/RP-1 gels, were highly viscoelastic. A history of research efforts which were conducted to formulate and characterize the properties of metallized propellants for various applications is also given

Medium Modifications of Charm and Charmonium in High-Energy Heavy-Ion Collisions

The production of charmonia in heavy-ion collisions is investigated within a kinetic theory framework simultaneously accounting for dissociation and regeneration processes in both quark-gluon plasma (QGP) and hadron-gas phases of the reaction. In-medium modifications of open-charm states (c-quarks, D-mesons) and the survival of J/psi mesons in the QGP are included as inferred from lattice QCD. Pertinent consequences on equilibrium charmonium abundances are evaluated and found to be especially relevant to explain the measured centrality dependence of the psi'/psi ratio at SPS. Predictions for recent In-In experiments, as well as comparisons to current Au-Au data from RHIC, are provided.Comment: 4 Latex pages including 4 eps figures and IOP style files. Talk given at the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter 2004, Oakland, CA USA, 11-17 Jan 2004. To appear in J. Phys.

The determination of gravity anomalies from geoid heights using the inverse Stokes' formula, Fourier transforms, and least squares collocation

A numerical method for the determination of gravity anomalies from geoid heights is described using the inverse Stokes formula. This discrete form of the inverse Stokes formula applies a numerical integration over the azimuth and an integration over a cubic interpolatory spline function which approximates the step function obtained from the numerical integration. The main disadvantage of the procedure is the lack of a reliable error measure. The method was applied on geoid heights derived from GEOS-3 altimeter measurements in the calibration area of the GEOS-3 satellite

Quarkonia and Heavy-Quark Relaxation Times in the Quark-Gluon Plasma

A thermodynamic T-matrix approach for elastic 2-body interactions is employed to calculate spectral functions of open and hidden heavy-quark systems in the Quark-Gluon Plasma. This enables the evaluation of quarkonium bound-state properties and heavy-quark diffusion on a common basis and thus to obtain mutual constraints. The two-body interaction kernel is approximated within a potential picture for spacelike momentum transfers. An effective field-theoretical model combining color-Coulomb and confining terms is implemented with relativistic corrections and for different color channels. Four pertinent model parameters, characterizing the coupling strengths and screening, are adjusted to reproduce the color-average heavy-quark free energy as computed in thermal lattice QCD. The approach is tested against vacuum spectroscopy in the open (D, B) and hidden (Psi and Upsilon) flavor sectors, as well as in the high-energy limit of elastic perturbative QCD scattering. Theoretical uncertainties in the static reduction scheme of the 4-dimensional Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are used to calculate Euclidean correlators which are discussed in light of lattice QCD results, while heavy-quark relaxation rates and diffusion coefficients are extracted utilizing a Fokker-Planck equation.Comment: 33 pages, 28 figure

Funding Long-Term Services and Supports (LTSS) for Working Aged Disabled Americans

There are a multitude of dilemmas faced today by over 3 million significantly disabled Americans, many of whom depend on Medicaid for Long-Term Services and Supports (LTSS) in obtaining the services they need to simply live. While the landmark 1990 Americans with Disabilities Act (ADA) has done a lot to improve the lives of people with disabilities, the reality is that using Medicaid as the vehicle for funding LTSS places unreasonable restrictions on disabled people who want to live independent lives and be as successful as possible. The Federal Government must change funding for LTSS in order to provide disabled Americans with real choices regarding living arrangements and maximize their earning potential without fear of being deprived of support they cannot live without. Part II of this note provides background information on LTSS (what they are, who uses them, what they cost, and how they are currently funded). Part III examines the Medicaid Program and specifically Medicaid HCBS17 Waiver Programs, which provide the bulk of LTSS funding today. A brief history of the federal laws, amendments, and policies that have impacted Medicaid LTSS are provided. Part IV analyzes an alternative to Medicaid for LTSS funding for those working-age disabled individuals who would not otherwise be Medicaid eligible. This section specifically focuses on recommendations from the congressionally established Commission on Long-Term Care and a pilot program proposed by the American Association for People with Disabilities (AAPD). Finally, Part V concludes that the Federal government must take action to establish a stand-alone, non-Medicaid Program to provide LTSS for working-age disabled Americans who are capable of working and living independently