9,585 research outputs found

    Fire Retardancy in 2001

    Get PDF
    Fire is a world-wide problem which claims lives and causes significant loss of property. Some of the problems are discussed and the solution delineated. This peer-reviewed volume is designed to be as the state-of-the-art. This chapter provides a perspective for current work

    A Class of Stationary Electromagnetic Vacuum Fields

    Get PDF
    This is the published version, also available here: http://dx.doi.org/10.1063/1.1666066.It is shown how a new class of stationary electromagnetic vacuum fields can be generated from solutions of Laplace's equation. These fields are a stationary generalization of the static electromagnetic vacuum fields of Weyl, Majumdar, and Papapetrou, and are plausibly interpreted as exterior fields of static or steadily moving distributions of charged dust having numerically equal charge and mass densities

    Effects of thermal motion on electromagnetically induced absorption

    Full text link
    We describe the effect of thermal motion and buffer-gas collisions on a four-level closed N system interacting with strong pump(s) and a weak probe. This is the simplest system that experiences electromagnetically induced absorption (EIA) due to transfer of coherence via spontaneous emission from the excited to ground state. We investigate the influence of Doppler broadening, velocity-changing collisions (VCC), and phase-changing collisions (PCC) with a buffer gas on the EIA spectrum of optically active atoms. In addition to exact expressions, we present an approximate solution for the probe absorption spectrum, which provides physical insight into the behavior of the EIA peak due to VCC, PCC, and wave-vector difference between the pump and probe beams. VCC are shown to produce a wide pedestal at the base of the EIA peak, which is scarcely affected by the pump-probe angular deviation, whereas the sharp central EIA peak becomes weaker and broader due to the residual Doppler-Dicke effect. Using diffusion-like equations for the atomic coherences and populations, we construct a spatial-frequency filter for a spatially structured probe beam and show that Ramsey narrowing of the EIA peak is obtained for beams of finite width

    Women and the Scottish Clerks' Association: from contempt to collegiality

    Get PDF
    First paragraph: This paper will trace the evolution of the attitudes expressed by the Scottish Clerks' Association (SCA) towards women in clerical work in the late nineteenth and early twentieth century. For women trying to establish careers in office work it was necessary to be accepted as colleagues by men in organisations like the SCA. But, as Sylvia Walby noted, explanations of the increasing presence of women in clerical work in the late nineteenth and early twentieth century have emphasised the role of employers as the main actors in the feminisation of clerical work, while the resistance (or acceptance) by male clerks has been given less attention. The evolution of the SCA's attitudes illustrates such resistance and then the growth of a kind of acceptance of women clerks in the early twentieth century; but this acceptance was within the context of male clerks' attempts to restructure their occupational group in order to preserve the better jobs for themselves
    • …
    corecore