A Frictional Cooling Demonstration Experiment with Protons

Muon cooling is the main technological obstacle in the building of a muon collider. A muon cooling scheme based on Frictional Cooling holds promise in overcoming this obstacle. An experiment designed to demonstrate the Frictional Cooling concept using protons was undertaken. Although the results were inconclusive in the observation of cooling, the data allowed for the qualification of detailed simulations which are used to simulate the performance of a muon collider.Comment: 24 Pages 16 figures 2 table

Rayleigh Scattering Density Measurements, Cluster Theory, and Nucleation Calculations at Mach 10

In an exploratory investigation, quantitative unclustered laser Rayleigh scattering measurements of density were performed in the air in the NASA Langley Research Center's 31 in. Mach 10 wind tunnel. A review of 20 previous years of data in supersonic and Mach 6 hypersonic flows is presented where clustered signals typically overwhelmed molecular signals. A review of nucleation theory and accompanying nucleation calculations are also provided to interpret the current observed lack of clustering. Data were acquired at a fixed stagnation temperature near 990Kat five stagnation pressures spanning 2.41 to 10.0 MPa (350 to 1454 psi) using a pulsed argon fluoride excimer laser and double-intensified charge-coupled device camera. Data averaged over 371 images and 210 pixels along a 36.7mmline measured freestream densities that agree with computed isentropic-expansion densities to less than 2% and less than 6% at the highest and lowest densities, respectively. Cluster-free Mach 10 results are compared with previous clustered Mach 6 and condensation-free Mach 14 results. Evidence is presented indicating vibrationally excited oxygen and nitrogen molecules are absorbed as the clusters form, release their excess energy, and inhibit or possibly reverse the clustering process. Implications for delaying clustering and condensation onset in hypersonic and hypervelocity facilities are discussed

The Effects of Nano-Hydroxyapatite in a Double Antibiotic Paste-Loaded Methycellulose Carrier on Dental Pulp Stem Cells

Indiana University-Purdue University Indianapolis (IUPUI)The effects of hydroxyapatite in a DAP-loaded MC carrier on dental pulp stem cells Introduction: Regenerative endodontic procedures (REP) require disinfection techniques to eliminate bacteria from the infected immature root canal system and promote new growth of the pulp-dentin complex. Double antibiotic paste (DAP), a mixture of ciprofloxacin and metronidazole, has shown efficacy in doing so while minimizing cytotoxicity on dental pulp stem cells (DPSC). Stem cells, scaffolding, and growth factors are necessary in the maturation, proliferation, and differentiation of mesenchymal stem cells into the root canal system. Nano-hydroxyapatite (n-HA) has a history of biocompatibility and, in addition, has shown promising effects as a tissue bioengineering material. Objective: The aim of this in vitro study was to investigate the proliferation and mineralization of DPSC in the presence of 1% DAP and methylcellulose (MC) with varying concentrations of nano-hydroxyapatite. Materials and Methods: DPSC were plated in 24-well plates containing culture media. The next day, semi-permeable 0.1 mm Transwell chambers were inserted into the wells to separate the reservoirs for medicaments. Treatment paste composed of methylcellulose containing 1% DAP with either 0.25%, 0.50%, or 1.0% nano-hydroxyapatite was added along with culture media. Methylcellulose alone and calcium hydroxide (Ultracal) were used as control groups. After 3 days, cells were evaluated for cytotoxic effects using an MTS proliferation assay (n = 10, in triplicate). DPSCs were also cultured with these medicaments for 7 days in osteogenic media and evaluated for alkaline phosphatase (ALP) activity and mineralization activity (n = 13, in triplicate). Comparisons between groups for differences in mineralization, BSA, and ALP activity were performed using analysis of variance (ANOVA), with different variances allowed for each group and a random effect included in the model to account for correlation within each of the three trials. A simulation-based model was used to adjust for multiple comparisons. Results: Addition of n-HA treatment groups increased mineralization significantly greater than calcium hydroxide, with MC alone and MC+DAP+0.5% HA providing the greatest effect. Regarding ALP, all HA concentrations performed significantly greater than MC and DAP concentrations. Proliferation demonstrated similar metabolic activity in all experimental groups with few comparisons significant. Conclusion: The challenge in REPs is to maintain survival, and preferably promote the proliferation and development of DPSCs into the pulp-dentin complex with a consistent treatment outcome. The combination of DAP with hydroxyapatite may allow for both disinfection and improved mineralization and cellular differentiation. This contribution has shown significant ability to increase stem cell differentiation into an osteogenic lineage as well as calcium deposition, indicating end goal results of regenerative procedures

The Resonant Dynamical Evolution of Small Body Orbits Among Giant Planets

Mean motion resonances (MMRs) can lead either to chaotic or regular motion. We report on a numerical experiment showing that even in one of the most chaotic regions of the Solar System - the region of the giant planets, there are numerous bands where MMRs can stabilize orbits of small bodies in a time span comparable to their lifetimes. Two types of temporary stabilization were observed: short period ($\sim10^{4}$ years) when a body was in a MMR with only one planet and long period (over $10^{5}$ years) when a body is located in overlapping MMRs with two or three planets. The experiment showed that the Main Belt region can be enriched by cometary material in its pre-active state due to temporary resonant interactions between small bodies and giant planets.Comment: 8 pages, 6 figure

Limits to the planet candidate GJ 436c

We report on H-band, ground-based observations of a transit of the hot Neptune GJ 436b. Once combined to achieve sampling equivalent to archived observations taken with Spitzer, our measurements reach comparable precision levels. We analyze both sets of observations in a consistent way, and measure the rate of orbital inclination change to be of 0.02+/-0.04 degrees in the time span between the two observations (253.8 d, corresponding to 0.03+/-0.05 degrees/yr if extrapolated). This rate allows us to put limits on the relative inclination between the two planets by performing simulations of planetary systems, including a second planet, GJ 436c, whose presence has been recently suggested (Ribas et al. 2008). The allowed inclinations for a 5 M_E super-Earth GJ 436c in a 5.2 d orbit are within ~7 degrees of the one of GJ 436b; for larger differences the observed inclination change can be reproduced only during short sections (<50%) of the orbital evolution of the system. The measured times of three transit centers of the system do not show any departure from linear ephemeris, a result that is only reproduced in <1% of the simulated orbits. Put together, these results argue against the proposed planet candidate GJ 436c.Comment: Replaced with accepted version. Minor language corrections. 4 pages, 4 figures, to appear in A&A Letter

Order statistics and heavy-tail distributions for planetary perturbations on Oort cloud comets

This paper tackles important aspects of comets dynamics from a statistical point of view. Existing methodology uses numerical integration for computing planetary perturbations for simulating such dynamics. This operation is highly computational. It is reasonable to wonder whenever statistical simulation of the perturbations can be much more easy to handle. The first step for answering such a question is to provide a statistical study of these perturbations in order to catch their main features. The statistical tools used are order statistics and heavy tail distributions. The study carried out indicated a general pattern exhibited by the perturbations around the orbits of the important planet. These characteristics were validated through statistical testing and a theoretical study based on Opik theory.Comment: 9 pages, 12 figures, submitted for publication in Astronomy and Astrophysic

Population structure and phenotypic variation of \u3ci\u3eSclerotinia sclerotiorum\u3c/i\u3e from dry bean (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e) in the United States

The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries (wmn) with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries (a) reflect the genetic diversity of the populations in the surrounding region and (b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns.We genotyped 366 isolates of S. sclerotiorum from producer fields and wmn surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n = 18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several wmn across the United States to account for both the phenotypic and genotypic variation that exists across regions