1,908 research outputs found

    4-H First Aid Kit.

    Get PDF
    2 p

    Unbiased flux calibration methods for spectral-line radio observations

    Full text link
    Position and frequency switching techniques used for the removal of the bandpass dependence of radio astronomical spectra are presented and discussed in detail. Both methods are widely used, although the frequency dependence of the system temperature and/or noise diode is often neglected. This leads to systematic errors in the calibration that potentially have a significant impact on scientific results, especially when using large-bandwidth receivers or performing statistical analyses. We present methods to derive an unbiased calibration using a noise diode, which is part of many heterodyne receivers. We compare the proposed methods and describe the advantages and bottlenecks of the various approaches. Monte Carlo simulations are used to qualitatively investigate both systematics and the error distribution of the reconstructed flux estimates about the correct flux values for the new methods but also the 'classical' case. Finally, the determination of the frequency-dependent noise temperature of the calibration diode using hot-cold measurements or observations of well-known continuum sources is also briefly discussed.Comment: 25 pages, 30 figures. Accepted for publication in A&

    Planetary observations at millimeter wavelengths

    Get PDF
    Observations of the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn were made at 3.1 mm and 8.6 mm wavelengths with a 16-foot radio telescope between March and August, 1971. Absolute brightness temperature data are given. All errors are one standard deviation and include uncertainties in antenna gain calibration. The solar and lunar temperatures are in excellent agreement with published observations. The planetary measurements at 3.1 mm are consistently higher than previous results. The implications of higher temperatures with respect to existing atmospheric and surface models are discussed

    Team Up Against Accidents.

    Get PDF
    2 p

    Motion Picture Production: To Run or Stay Made in the U.S.A.

    Get PDF

    Mars riometer system

    Get PDF
    A riometer (relative ionospheric opacity meter) measures the intensity of cosmic radio noise at the surface of a planet. When an electromagnetic wave passes through the ionosphere collisions between charged particles (usually electrons) and neutral gases remove energy from the wave. By measuring the received signal intensity at the planet's surface and comparing it to the expected value (the quietday curve) a riometer can deduce the absorption (attenuation) of the trans-ionospheric signal. Thus the absorption measurements provide an indication of ionisation changes occurring in the ionosphere. To avoid the need for orbiting sounders riometers use the cosmic noise background as a signal source. Earth-based systems are not subject to the challenging power, volume and mass restriction that would apply to a riometer for Mars. Some Earth-based riometers utilise phased-array antennas in order to provide an imaging capability.UnpublishedVienna - Austria3.9. Fisica della magnetosfera, ionosfera e meteorologia spazialeope

    Removing Green Scum from Tanks and Reservoirs with Bluestone.

    Get PDF
    3p

    Social relations in teacher\u27s daily routine. Empirical findings in the context of current professional problems

    Full text link
    Prestigeverluste und schlechtere Arbeitsbedingungen beeinträchtigen derzeit die Situation der Lehrer/innen, die ohnehin schon unter hohen Belastungen leiden. Eine zunehmend heterogene und wenig motivierte Schülerschaft, anspruchsvolle und kritische Eltern sowie Kooperations- und Konkurrenzprobleme im Kollegium erschweren die pädagogische Tätigkeit. Entlastung und bessere Beziehungen lassen sich nur durch günstigere Rahmenbedingungen und eine effizientere Interessenvertretung erreichen. (DIPF/Orig.)A loss of status and worsening work conditions negatively affect the present situation of teachers already suffering from a high workload. An increasingly heterogeneous and poorly motivated student body on the one hand and exacting and critical parents on the other hand as well as problems of weak cooperation and rivalry among the members of the teaching staff put a heavy strain on the pedagogical work. In order to reduce strains and to improve social relations better (financial) conditions and a more effective representation of interests are necessary. (DIPF/Orig.

    Review of socialization at school. A qualitative study with teacher students

    Full text link
    Lehramtsstudierende haben ihre eigene Schulzeit häufig in guter oder in negativer Erinnerung. Positive Effekte sehen sie in der persönlichen Entwicklung, im Zuwachs sozialer Kompetenzen und in den Freundschaften zu Mitschülern, negativ werden vor allem Leistungsdruck und das Verhalten der Lehrerinnen und Lehrer bewertet. (DIPF/Orig.)Teacher students recollect their own school experience often as good or bad. They value as positive influences on their personal development, an increase of social competence and the friendship to fellow-pupils, as negative they remember above all achievement pressure and the behavior of male and female teachers. (DIPF/Orig.

    Induction, characterization, and cell transfer of autoimmune tubulointerstitial nephritis

    Get PDF
    Induction, characterization, and cell transfer of autoimmune tubulointerstitial nephritis. Autoimmune tubulointerstitial nephritis (TIN) was induced in Lewis (LEW) rats by immunization with homologous Brown–Norway (BN) rat renal basement membrane (RBM), complete Freund's adjuvant and Bordetella pertussis vaccine. The BN strain has a tubular basement membrane (TBM) antigen (Ag+) detectable by immunofluorescence which is lacking in unmodified LEW rat TBM. Development of TIN in LEW rats correlated with TBM Ag+ immunogens from homologous and heterologous RBM preparations. By day 14 after immunization TIN developed characterized by elevated serum creatinine levels and by tubular destruction with focal, circumscribed lesions containing epithelioid cells, giant cells and mononuclear cell infiltrates. Approximately 60% of the mononuclear cells bore T cell antigens with most cells expressing la markers. Immunofluorescence and elution studies revealed no selective IgG fixation to TBM at day 14 despite high titers of circulating alloantibody reactive with the immunizing TBM. Intravenous transfer of LNC and/or splenic cells (3.5 to 7 × 108) to naive LEW rats resulted in less severe but histologically identical TIN in seven days with T cell subpopulations similar to those seen in the active model. This model strongly suggests an initiating role for cell–mediated immunity in TIN in the rat and may provide a parallel to human TIN
    • …
    corecore