Low energy neutron propagation in MCNPX and GEANT4

Simulations of neutron background from rock for underground experiments are presented. Neutron propagation through two types of rock, lead and hydrocarbon material is discussed. The results show a reasonably good agreement between GEANT4, MCNPX and GEANT3 in transporting low-energy neutrons.Comment: 9 Figure

Study of methane fuel for subsonic transport aircraft

The cost and performance were defined for commercial transport using liquid methane including its fuel system and the ground facility complex required for the processing and storage of methane. A cost and performance comparison was made with Jet A and hydrogen powered aircraft of the same payload and range capability. Extensive design work was done on cryogenic fuel tanks, insulation systems as well as the fuel system itself. Three candidate fuel tank locations were evaluated, i.e., fuselage tanks, wing tanks or external pylon tanks

Use of linear discriminant function analysis in seed morphotype relationship study in 31 Lima bean (Phaseolus lunatus L.) accessions in Ghana

Variation in seed morphology of the Lima bean in 31 accessions was studied. Data were collected on 100-seed weight, seed length and seed width. The differences among the accessions were significant, based on the three seed characteristics. K-means cluster analysis grouped the 31 accessions into four distinct groups, representing four different morphotypes. Mahalanobis distances (D2) among the groups were highly significant. The four different morphotypes were attributed to the Mesoamerican gene pool, comprising the cultigroups Sieva-Big Lima, Potato-Sieva and Potato. Sub-cultigroups of the Sieva-Big Lima and Potato cultigroups due to differences in seed weight were suggested.Variation en morphologie de graine du haricot de Lima en trente accessions était étudiée. Des données étaient collectées sur poids de 100 graines, longueur de graine et largeur de graine. Il y avait des différences considérables parmi les accessions basées sur les trois caractéristiques de graine. Analyse du régime par K-moyens groupait les 31 accessions en quatre groupes distincts, représentant quatre morphotypes différents. Les distances (D2) Mahalanobis parmi les groupes étaient hautement considérables. Les quatre morphotypes différents étaient attribués au bagage héréditaire de Mesoaméricain, comprenant les groupes de cultures: Sieva-Grand Lima, Patate-Sieva et Patate. Les groupes de sous-cultures de Sieva-Grand Lima et Patate groupes de culture dû aux différences en poids de graine étaient suggérées. Ghana Journal of Agricultural Science Vol. 39 (1) 2006: pp. 87-9

Interrelationships Within the Bacterial Flora of the Female Genital Tract

Analysis of 240 consecutive vaginal swabs using the compatibility profile technique revealed that only 2 bacteria have the ability to be a sole isolate and as such a candidate to be a major aerobic regulator of the bacterial flora of the female genital tract (BFFGT). Compatibility profiles of Lactobacillus and Gardnerella vaginalis have shown that these organisms shared compatibility profiling for the majority of the normal bacterial constituents of the female genital tract. Dominance disruption appears to come from the addition of compatible co-isolates and presumed loss of numerical superiority. These phenomena appear to be the keys to reregulation of BFFGT. Lactobacillus appears to be the major regulator of both G. vaginalis and anaerobic bacteria. When additional organisms are added to the bacterial flora, they may add to or partially negate the inhibitory influence of Lactobacillus on the BFFGT. Inhibitor interrelationships appear to exist between coagulase-negative staphylococci and Staphylococcus aureus and the group B streptococci (GBS) and other beta hemolytic streptococci. Facilitating interrelationships appear to exist between S. aureus and the GBS and selected Enterobacteriaceae

Mach 4 free-jet tunnel starting experiments for a hypersonic research engine model causing high blockage

Tests of a full scale hypersonic research engine (HRE) were conducted in the hypersonic tunnel facility at Mach numbers of 5, 6, and 7. Since the HRE would cause a rather high blockage (48.83 percent of the nozzle area), subscale tests were conducted in various available small wind tunnels prior to the full scale tests to study the effects of model blockage on tunnel starting. The results of the Mach 4 subscale tests which utilized a model system at 0.0952 scale which simulated the HRE in the test section of the tunnel are presented. A satisfactory tunnel starting could not be achieved by varying the free jet length or diffuser size nor by inserting the model into the test stream after tunnel starting. However, the installation of a shroud around the HRE model allowed the tunnel to start with the model preset in the tunnel at a tunnel stagnation pressure to atmospheric exit pressure ratio of 13.4. The simulation of the discharge of instrumentation cooling water and the addition of test hardware at the aft end of the HRE model did not have a significant effect on the tunnel starting

A Distance-Limited Imaging Survey of Sub-Stellar Companions to Solar Neighborhood Stars

We report techniques and results of a Palomar 200-inch (5 m) adaptive optics imaging survey of sub-stellar companions to solar-type stars. The survey consists of Ks coronagraphic observations of 21 FGK dwarfs out to 20 pc (median distance about 17 pc). At 1-arcsec separation (17 projected AU) from a typical target system, the survey achieves median sensitivities 7 mag fainter than the parent star. In terms of companion mass, that corresponds to sensitivities of 50MJ (1 Gyr), 70MJ (solar age), and 75MJ (10 Gyr), using the evolutionary models of Baraffe and colleagues. Using common proper motion to distinguish companions from field stars, we find that no system shows positive evidence of a previously unknown substellar companion (searchable separation about 20-250 projected AU at the median target distance).Comment: 29 pages, 5 figures. Carson et al. 2008, AJ, in pres

Sphaleron Effects Near the Critical Temperature

We discuss one-loop radiative corrections to the sphaleron-induced baryon number-violating transition rate near the electroweak phase transition in the standard model. We emphasize that in the case of a first-order transition a rearrangement of the loop expansion is required close to the transition temperature. The corresponding expansion parameter, the effective 3-dimensional gauge coupling approaches a finite $\lambda$ dependent value at the critical temperature. The $\lambda$ (Higgs mass) dependence of the 1-loop radiative corrections is discussed in the framework of the heat kernel method. Radiative corrections are small compared to the leading sphaleron contribution as long as the Higgs mass is small compared to the W mass. To 1-loop accuracy, there is no Higgs mass range compatible with experimental limits where washing-out of a B+L asymmetry could be avoided for the minimal standard model with one Higgs doublet.Comment: 17 pages, RevTeX, (4 figures in a separate uuencoded file), HD-THEP-93-23re