Mini-BRU/BIPS foil bearing development

The analysis revealed the failure agent to be a combination of poor teflon coating adhesion, a decrease in bearing sway space and, possibly, lack of flushing flow through the bearing. A change in Teflon coating vendors provided substantially improved coating quality and surface finish. The sway space was increased and the cooling bleed flow was adjusted to flush the bearing. These changes were included in a test conducted in the WHL from 6 April to 22 May 1978 which resulted in the completion of 1006.9 hours of operation at temperature and load. Post-test inspection revealed the bearings to be in excellent condition and capable of completing a much longer test

Is nonhelical hydromagnetic turbulence peaked at small scales?

Nonhelical hydromagnetic turbulence without an imposed magnetic field is considered in the case where the magnetic Prandtl number is unity. The magnetic field is entirely due to dynamo action. The magnetic energy spectrum peaks at a wavenumber of about 5 times the minimum wavenumber in the domain, and not at the resistive scale, as has previously been argued. Throughout the inertial range the spectral magnetic energy exceeds the kinetic energy by a factor of about 2.5, and both spectra are approximately parallel. At first glance, the total energy spectrum seems to be close to k^{-3/2}, but there is a strong bottleneck effect and it is suggested that the asymptotic spectrum is k^{-5/3}. This is supported by the value of the second order structure function exponent that is found to be \zeta_2=0.70, suggesting a k^{-1.70} spectrum.Comment: 6 pages, 6 figure

Evidence Of Dark Matter Annihilations In The WMAP Haze

The WMAP experiment has revealed an excess of microwave emission from the region around the center of our Galaxy. It has been suggested that this signal, known as the ``WMAP Haze'', could be synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. In this letter, we revisit this possibility. We find that the angular distribution of the WMAP Haze matches the prediction for dark matter annihilations with a cusped density profile, $\rho(r) \propto r^{-1.2}$ in the inner kiloparsecs. Comparing the intensity in different WMAP frequency bands, we find that a wide range of possible WIMP annihilation modes are consistent with the spectrum of the haze for a WIMP with a mass in the 100 GeV to multi-TeV range. Most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, $\sigma v \sim 3 \times 10^{-26}$ cm$^3$/s. No boost factors are required. If dark matter annihilations are in fact responsible for the WMAP Haze, and the slope of the halo profile continues into the inner Galaxy, GLAST is expected to detect gamma rays from the dark matter annihilations in the Galactic Center if the WIMP mass is less than several hundred GeV.Comment: 4 pages, 3 figure

Indoor Navigation with MEMS sensors

AbstractAccurate positioning becomes extremely important for modern application like indoor navigation and location-based services. Standalone GPS cannot meet this accuracy. In this paper a method to couple GPS and a high resolution MEMS pressure sensor is presented to improve vertical as well as horizontal (in urban canyon environment) positioning. Further, a step counter based on an accelerometer is improved with an altimeter for stair detection and automatic step length adaptation for dead reckoning inside buildings. Finally, a stand-alone system accurately tracks floor levels inside buildings, using only a pressure sensor

Analysis of WMAP 7-year Temperature Data: Astrophysics of the Galactic Haze

We analyse WMAP 7-year temperature data, jointly modeling the cosmic microwave background (CMB) and Galactic foreground emission. We use the Commander code based on Gibbs sampling. Thus, from the WMAP7 data, we derive simultaneously the CMB and Galactic components on scales larger than 1deg with sensitivity improved relative to previous work. We conduct a detailed study of the low-frequency foreground with particular focus on the "microwave haze" emission around the Galactic center. We demonstrate improved performance in quantifying the diffuse galactic emission when Haslam 408MHz data are included together with WMAP7, and the spinning and thermal dust emission is modeled jointly. We also address the question of whether the hypothetical galactic haze can be explained by a spatial variation of the synchrotron spectral index. The excess of emission around the Galactic center appears stable with respect to variations of the foreground model that we study. Our results demonstrate that the new galactic foreground component - the microwave haze - is indeed present.Comment: 16 pages, 16 figures, Published on Ap

Effectiveness of Topical Antibiotics in Treating Corals Affected by Stony Coral Tissue Loss Disease

Since 2014, Stony Coral Tissue Loss Disease (SCTLD) has led to mass mortality of the majority of hard coral species on the Florida Reef Tract. Following the successful treatment of SCTLD lesions on laboratory corals using water dosed with antibiotics, two topical pastes were developed as vehicles to directly apply antibiotic treatments to wild corals. These pastes were tested as placebos and with additions of amoxicillin on active SCTLD lesions on multiple coral species. The effectiveness of the pastes without antibiotics (placebo treatments) was 4% and 9%, no different from untreated controls. Adding amoxicillin to both pastes significantly increased effectiveness to 70% and 84%. Effectiveness with this method was seen across five different coral species, with success rates of the more effective paste ranging from 67% (Colpophyllia natans) to 90% (Orbicella faveolata and Montastraea cavernosa). Topical antibiotic application is a viable and effective tool for halting disease lesions on corals affected by SCTLD

Magnetic field generation in fully convective rotating spheres

Magnetohydrodynamic simulations of fully convective, rotating spheres with volume heating near the center and cooling at the surface are presented. The dynamo-generated magnetic field saturates at equipartition field strength near the surface. In the interior, the field is dominated by small-scale structures, but outside the sphere by the global scale. Azimuthal averages of the field reveal a large-scale field of smaller amplitude also inside the star. The internal angular velocity shows some tendency to be constant along cylinders and is ``anti-solar'' (fastest at the poles and slowest at the equator).Comment: 12 pages, 11 figures, 2 tables, to appear in the 10 Feb issue of Ap

Understanding micro-image configurations in quasar microlensing

The micro-arcsecond scale structure of the seemingly point-like images in lensed quasars, though unobservable, is nevertheless much studied theoretically, because it affects the observable (or macro) brightness, and through that provides clues to substructure in both source and lens. A curious feature is that, while an observable macro-image is made up of a very large number of micro-images, the macro flux is dominated by a few micro-images. Micro minima play a key role, and the well-known broad distribution of macro magnification can be decomposed into narrower distributions with 0,1,2,3,... micro minima. This paper shows how the dominant micro-images exist alongside the others, using the ideas of Fermat's principle and arrival-time surfaces, alongside simulations.Comment: Accepted for publication in MNRA