Magnetoroton scattering by phonons in the fractional quantum Hall regime

Motivated by recent phonon spectroscopy experiments in the fractional quantum Hall regime we consider processes in which thermally excited magnetoroton excitations are scattered by low energy phonons. We show that such scattering processes can never give rise to dissociation of magnetorotons into unbound charged quasiparticles as had been proposed previously. In addition we show that scattering of magnetorotons to longer wavelengths by phonon absorption is possible because of the shape of the magnetoroton dispersion curve and it is shown that there is a characteristic cross-over temperature above which the rate of energy transfer to the electron gas changes from an exponential (activated) to a power law dependence on the effective phonon temperature.Comment: LaTex document, 3 eps figures. submitted to Phys Rev

Mid-infrared Period-Luminosity Relations of RR Lyrae Stars Derived from the WISE Preliminary Data Release

Interstellar dust presents a significant challenge to extending parallax-determined distances of optically observed pulsational variables to larger volumes. Distance ladder work at mid-infrared wavebands, where dust effects are negligible and metallicity correlations are minimized, have been largely focused on few-epoch Cepheid studies. Here we present the first determination of mid-infrared period-luminosity (PL) relations of RR Lyrae stars from phase-resolved imaging using the preliminary data release of the Wide-Field Infrared Survey Explorer (WISE). We present a novel statistical framework to predict posterior distances of 76 well-observed RR Lyrae that uses the optically constructed prior distance moduli while simultaneously imposing a power-law PL relation to WISE-determined mean magnitudes. We find that the absolute magnitude in the bluest WISE filter is M_W1 = (-0.421+-0.014) - (1.681+-0.147)*log(P/0.50118 day), with no evidence for a correlation with metallicity. Combining the results from the three bluest WISE filters, we find that a typical star in our sample has a distance measurement uncertainty of 0.97% (statistical) plus 1.17% (systematic). We do not fundamentalize the periods of RRc stars to improve their fit to the relations. Taking the Hipparcos-derived mean V-band magnitudes, we use the distance posteriors to determine a new optical metallicity-luminosity relation which we present in Section 5. The results of this analysis will soon be tested by HST parallax measurements and, eventually, with the Gaia astrometric mission.Comment: 33 pages, 12 figures, 2 tables. Accepted for publication in ApJ, June 27th, 201

Using Intermittent Sand Filters of Various Depths to Remove NH3-N, NO3N and NO2N from the Wastewater of Sugar Milling Factory

Intermittent sand filter systems have been used in wastewater treatment according to Selecky (2012) especially their application for on-site wastewater management. Intermittent sand filters have not been used to treat effluent from sugar factories in Kenya. There is very limited information on how to optimize their application in treating effluent from sugar factory in Kenya. This study focused on optimization of intermittent sand filter used in treatment of wastewater from sugar factory. Samples of wastewater were randomly taken from Kibos Sugar and Allied factories. These samples were loaded into sand filters with different sand depths of 0.30, 0.45 and 0.60m. Different loading rates, volumes and frequencies were applied for each depth. Samples from the filtrate were collected and analyzed in the laboratory for NH3-N, NO3-N and NO2-N values. The data was subjected to analysis of variance for fractional factorial (ANOVA) using the GenStat Version 13.2 computer programme. Wastewater generated from the sugar factories had NH3-N, NO3-N and NO2-N were within the WHO acceptable limits. The sugar factory managers targeting to remove NO3-N should use a sand filter with a depth of 0.45m by loading it at a rate of 2L/min, volume of 30L and frequency of 12hrs. To remove NO2N using a sand filter of 0.45 m deep, they should use a loading rate of 4L/min, loading volume of 10L and loading frequency of 12hrs. Keywords: Effluent, factory, filter, intermittent, sand, sugar, wastewater

Modeling Multi-Wavelength Stellar Astrometry. I. SIM Lite Observations of Interacting Binaries

Interacting binaries consist of a secondary star which fills or is very close to filling its Roche lobe, resulting in accretion onto the primary star, which is often, but not always, a compact object. In many cases, the primary star, secondary star, and the accretion disk can all be significant sources of luminosity. SIM Lite will only measure the photocenter of an astrometric target, and thus determining the true astrometric orbits of such systems will be difficult. We have modified the Eclipsing Light Curve code (Orosz & Hauschildt 2000) to allow us to model the flux-weighted reflex motions of interacting binaries, in a code we call REFLUX. This code gives us sufficient flexibility to investigate nearly every configuration of interacting binary. We find that SIM Lite will be able to determine astrometric orbits for all sufficiently bright interacting binaries where the primary or secondary star dominates the luminosity. For systems where there are multiple components that comprise the spectrum in the optical bandpass accessible to SIM Lite, we find it is possible to obtain absolute masses for both components, although multi-wavelength photometry will be required to disentangle the multiple components. In all cases, SIM Lite will at least yield accurate inclinations, and provide valuable information that will allow us to begin to understand the complex evolution of mass-transferring binaries. It is critical that SIM Lite maintains a multi-wavelength capability to allow for the proper deconvolution of the astrometric orbits in multi-component systems.Comment: 12 pages, 6 figures, 6 tables. Accepted for publication in the Astrophysical Journa

Interferometric Astrometry of Proxima Centauri and Barnard's Star Using Hubble Space Telescope Fine Guidance Sensor 3: Detection Limits for sub-Stellar Companions

We report on a sub-stellar companion search utilizing interferometric fringe-tracking astrometry acquired with Fine Guidance Sensor 3 (FGS 3) on the Hubble Space Telescope. Our targets were Proxima Centauri and Barnard's Star. We obtain absolute parallax values for Proxima Cen pi_{abs} = 0.7687 arcsecond and for Barnard's Star pi_{abs} = 0.5454 arcsecond. Once low-amplitude instrumental systematic errors are identified and removed, our companion detection sensitivity is less than or equal to one Jupiter mass for periods longer than 60 days for Proxima Cen. Between the astrometry and the radial velocity results we exclude all companions with M > 0.8M_{Jup} for the range of periods 1 < P < 1000 days. For Barnard's Star our companion detection sensitivity is less than or equal to one Jupiter mass for periods long er than 150 days. Our null results for Barnard's Star are consistent with those of Gatewood (1995).Comment: 35 pages, 13 figures, to appear in August 1999 A

Geology of the Northwestern Krania Basin

The Greveniotiki Pindos Mountains of Greece showcases the tectonics affecting the Central Mediterranean; however no detailed geological maps have been produced of the region. In this study we present a 1:10000 geological map of Mount Orliakas and its surrounding areas, including westernmost parts of the Pindos Ophiolite complex and the Mesohellenic basin. We also provide new lithological, structural, and palaeontological discussions of the region and give new evidence for the provenance of the Kranea Formation