Monte Carlo calculations of high energy nucleon meson cascades and applications to galactic cosmic ray transport

Results obtained using a recently developed calculational method for determining the nucleon-meson cascade induced in thick materials by high-energy nucleons and charged pions are presented. The calculational method uses the intranuclear-cascade-evaporation model to treat nonelastic collisions by particles with energies approximately or smaller than GeV and an extrapolation model at higher energies. The following configurations are considered: (1) 19.2-GeV/c protons incident on iron; (2) 30.3-GeV/c protons incident on iron; (3) solar and galactic protons incident on the moon, and (4) galactic protons incident on tissue. For the first three configurations, experimental results are available and comparisons between the experimental and calculated results are given

Apollo experience report: The cryogenic storage system

A review of the design, development, and flight history of the Apollo cryogenic storage system and of selected components within the system is presented. Discussions are presented on the development history of the pressure vessels, heaters, insulation, and selected components. Flight experience and operational difficulties are reported in detail to provide definition of the problems and applicable corrective actions

Dynamics on the Way to Forming Glass: Bubbles in Space-time

We review a theoretical perspective of the dynamics of glass forming liquids and the glass transition. It is a perspective we have developed with our collaborators during this decade. It is based upon the structure of trajectory space. This structure emerges from spatial correlations of dynamics that appear in disordered systems as they approach non-ergodic or jammed states. It is characterized in terms of dynamical heterogeneity, facilitation and excitation lines. These features are associated with a newly discovered class of non-equilibrium phase transitions. Equilibrium properties have little if anything to do with it. The broken symmetries of these transitions are obscure or absent in spatial structures, but they are vivid in space-time (i.e., trajectory space). In our view, the glass transition is an example of this class of transitions. The basic ideas and principles we review were originally developed through the analysis of idealized and abstract models. Nevertheless, the central ideas are easily illustrated with reference to molecular dynamics of more realistic atomistic models, and we use that illustrative approach here.Comment: 21 pages, 8 figures. Submitted to Annu. Rev. Phys. Che

Early Cementation of the Short Creek Oolite Member, Boone Formation (Osagean, Lower Mississippian), Northern Arkansas

The Short Creek Oolite is the only formally named member of the Boone Formation in northern Arkansas. It lacks bedding features, and oolith concentrations that would suggest a shoal environment, and it occurs at variable stratigraphic horizons within the upper Boone Formation consistent with episodic deposition as grainflow slurries. As with modern oolite examples, such as Joulters Cays, Bahamas, the Short Creek preserves numerous intraclasts, and at least one large olistolith indicating an early cementation history

Structure and thermodynamics of colloid-polymer mixtures: a macromolecular approach

The change of the structure of concentrated colloidal suspensions upon addition of non-adsorbing polymer is studied within a two-component, Ornstein-Zernicke based liquid state approach. The polymers' conformational degrees of freedom are considered and excluded volume is enforced at the segment level. The polymer correlation hole, depletion layer, and excess chemical potentials are described in agreement with polymer physics theory in contrast to models treating the macromolecules as effective spheres. Known depletion attraction effects are recovered for low particle density, while at higher densities novel many-body effects emerge which become dominant for large polymers.Comment: 7 pages, 4 figures; to be published in Europhys. Let

Potential model calculations and predictions for heavy quarkonium

We investigate the spectroscopy and decays of the charmonium and upsilon systems in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which allows us to compare the results for both perturbative and nonperturbative treatments of the potential. As well as comparing the mass spectra, radiative widths and leptonic widths with the available data, we include a discussion of the errors on the parameters contained in the potential, the effect of mixing on the leptonic widths, the Lorentz nature of the confining potential and the possible $c\bar{c}$ interpretation of recently discovered charmonium-like states.Comment: Physical Review published versio

Imaging the Ionized Disk of the High-Mass Protostar Orion-I

We have imaged the enigmatic radio source-I (Orion-I) in the Orion-KL nebula with the VLA at 43 GHz with 34 mas angular resolution. The continuum emission is highly elongated and is consistent with that expected from a nearly edge-on disk. The high brightness and lack of strong molecular lines from Orion-I can be used to argue against emission from dust. Collisional ionization and H-minus free-free opacity, as in Mira variables, require a central star with >10^5 Lsun, which is greater than infrared observations allow. However, if significant local heating associated with accretion occurs, lower total luminosities are possible. Alternatively, photo-ionization from an early B-type star and p+/e- bremsstrahlung can explain our observations, and Orion-I may be an example of ionized accretion disk surrounding a forming massive star. Such accretion disks may not be able to form planets efficiently.Comment: 16 pages, 1 table, 3 figure