19,990 research outputs found

    No Evidence for [O III] Variability in Mrk 142

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    Using archival data from the 2008 Lick AGN Monitoring Project, Zhang & Feng (2016) claimed to find evidence for flux variations in the narrow [O III] emission of the Seyfert 1 galaxy Mrk 142 over a two-month time span. If correct, this would imply a surprisingly compact size for the narrow-line region. We show that the claimed [O III] variations are merely the result of random errors in the overall flux calibration of the spectra. The data do not provide any support for the hypothesis that the [O III] flux was variable during the 2008 monitoring period.Comment: Response to Zhang & Feng 2016, MNRAS Letters, 457, L64 (arXiv:1512.07673). Accepted for publication in MNRAS Letters. 5 pages, 2 figure

    Investigation of a lineament expressed in an oblique Apollo 9 photograph

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    The author has identified the following significant results. A linear topographic feature, referred to as the New York Mountains lineament, was recognized in an oblique Apollo 9 photograph to extend from the Providence Mountains of California to near Lake Mead, Arizona. In subsequent vertical ERTS-1 imagery this feature was found to have vague and indistinct expression. A study was conducted to determine the possible geologic origin(s) of the lineament and to explain its anomalous expression in the Apollo 9 photograph. The results suggest that the apparent expression of the lineament is due to a combination of the oblique view of the Apollo photograph, low sun angle illumination of southeast facing slopes, shadowing of northwest facing slopes, and linear snow line along the southeastern flank of the New York Mountains. No geologic or structural causes for the lineament have been found

    Model for Cumulative Solar Heavy Ion Energy and Linear Energy Transfer Spectra

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    A probabilistic model of cumulative solar heavy ion energy and LET spectra is developed for spacecraft design applications. Spectra are given as a function of confidence level, mission time period during solar maximum and shielding thickness. It is shown that long-term solar heavy ion fluxes exceed galactic cosmic ray fluxes during solar maximum for shielding levels of interest. Cumulative solar heavy ion fluences should therefore be accounted for in single event effects rate calculations and in the planning of space missions

    Pentaquark searches at FOCUS

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    We find no evidence for high-energy photoproduction of pentaquarks at 1540 MeV/c2c^2, 1862 MeV/c2c^2, or 3099 MeV/c2c^2 using decay modes pKS0pK_S^0, Ξπ\Xi^-\pi^-, and D()pD^{(*)-}p, respectively.Comment: Proceedings from talk at 2004 DPF Meeting at University of California, Riversid

    Carbon isotope fractionation during aerobic biodegradation of trichloroethene by Burkholderia cepacia G4: a tool to map degradation mechanisms

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    The strain Burkholderia cepacia G4 aerobically mineralized trichloroethene (TCE) to CO2 over a time period of similar to20 h. Three biodegradation experiments were conducted with different bacterial optical densities at 540 nm (OD(540)s) in order to test whether isotope fractionation was consistent. The resulting TCE degradation was 93, 83.8, and 57.2% (i.e., 7.0, 16.2, and 42.8% TCE remaining) at OD(540)s of 2.0, 1.1, and 0.6, respectively. ODs also correlated linearly with zero-order degradation rates (1.99, 1.11, and 0.64 mumol h(-1)). While initial nonequilibrium mass losses of TCE produced only minor carbon isotope shifts (expressed in per mille delta C- 13(VPDB)), they were 57.2, 39.6, and 17.0parts per thousand between the initial and final TCE levels for the three experiments, in decreasing order of their OD(540)s. Despite these strong isotope shifts, we found a largely uniform isotope fractionation. The latter is expressed with a Rayleigh enrichment factor, E, and was -18.2 when all experiments were grouped to a common point of 42.8% TCE remaining. Although, decreases of epsilon to -20.7 were observed near complete degradation, our enrichment factors were significantly more negative than those reported for anaerobic dehalogenation of TCE. This indicates typical isotope fractionation for specific enzymatic mechanisms that can help to differentiate between degradation pathways
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