Comments on alternative calculations of the broadening of spectral lines of neutral sodium by H-atom collisions

With the exception of the sodium D-lines recent calculations of line broadening cross-sections for several multiplets of sodium by Leininger et al (2000) are in substantial disagreement with cross-sections interpolated from the tables of Anstee and O'Mara (1995) and Barklem and O'Mara (1997). The discrepancy is as large as a factor of three for the 3p-4d multiplet. The two theories are tested by using the results of each to synthesize lines in the solar spectrum. It is found that generally the data from the theory of Anstee, Barklem and O'Mara produce the best match to the observed solar spectrum. It is found, using a simple model for reflection of the optical electron by the potential barrier between the two atoms, that the reflection coefficient is too large for avoided crossings with the upper states of subordinate lines to contribute to line broadening, supporting the neglect of avoided ionic crossings by Anstee, Barklem and O'Mara for these lines. The large discrepancies between the two sets of calculations is a result of an approximate treatment of avoided ionic crossings for these lines by Leininger et al (2000).Comment: 18 pages, 5 ps figures included, to appear in J Phys B: At. Mol. Opt. Phy

Lesbian and bisexual women's human rights, sexual rights and sexual citizenship: negotiating sexual health in England.

Lesbian and bisexual women's sexual health is neglected in much Government policy and practice in England and Wales. This paper examines lesbian and bisexual women's negotiation of sexual health, drawing on findings from a small research project. Themes explored include invisibility and lack of information, influences on decision-making and sexual activities and experiences of services and barriers to sexual healthcare. Key issues of importance in this respect are homophobic and heterosexist social contexts. Drawing on understandings of lesbian, gay and bisexual human rights, sexual rights and sexual citizenship, it is argued that these are useful lenses through which to examine and address lesbian and bisexual women's sexual health and related inequalities

Multi-Messenger Measurements of the Static Structure of Shock-Compressed Liquid Silicon at 100 GPa

Ionic structure of high pressure, high temperature fluids is a challenging theoretical problem with applications to planetary interiors and fusion capsules. Here we report a multi-messenger platform using velocimetry and \textit{in situ} angularly and spectrally resolved X-ray scattering to measure the thermodynamic conditions and ion structure factor of materials at extreme pressures. We document the pressure, density, and temperature of shocked silicon near 100 GPa with uncertainties of 6%, 2%, and 20%, respectively. The measurements are sufficient to distinguish between and rule out some ion screening models.Comment: Main Paper: 5 pages, 4 figures. Supplementary Material: 9 pages, 8 figure

The scattering of line radiation-II. Velocity-noncorrelated scattering

An investigation is carried out into the effects of using different atomic models of the radiation scattering event with velocity-noncorrelated scattering (a physical process introduced in a previous paper). Special emphasis is placed on those models of the scattering event which lead to complete frequency redistribution in the radiation viewed by an observer at a large from the atmosphere being investigated. Of the three different models of the atomic radiation scattering event used, two were found to produce complete frequency redistribution. It is pointed out that the significance of the derivation of the mathematical forms describing complete frequency redistribution does not lie in the functional forms themselves, which have known and used with great effect for many years, but rather in the physical interpretation of the radiation scattering event which must be used to obtain the particular mathematical expressions

The Use of Computational Fluid Dynamics in the Thermal Design of Rotating Electrical Machines

Thermal constraints impose limitations on the power capability of many electric motors and generators. However, inadequate data on ventilation air flows and convection heat transfer coefficients hamper the design process. Computational fluid dynamics (CFD) presents an opportunity to predict air flow and heat transfer in many situations. However, the complex geometries combined with rotation in the end regions of electric motors and generators present significant difficulties for CFD. An experimental study of air flow and heat transfer in the end region of a 200 kW 2 pole totally enclosed, fan cooled (TEFC) induction motor was carried out. Detailed measurements of heat transfer coefficient around the end windings and frame were made along with measurements of windage loss and airflow at particular locations within the end region. These were compared with a detailed model of the end region using the CFD software Fluent UNS and good agreement was found. The results are presented and the reasons for the difference between the measured values and CFD predictions are discussed. It is concluded that general purpose CFD software is now at a stage of development where it can be used in a design office environment to undertake design analysis of electrical machines