Current Uncertainties in the Use of Cepheids as Distance Indicators

The methods of calibrating the luminosities of galactic Cepheids and determining Cepheid reddenings are considered in some detail. Together with work on NGC4258 this suggests that the calibration presented is valid to about 0.1mag (s.e.) at least for Cepheids with near-solar abundances. Metallicity effects are considered, partly through the use of non-Cepheid moduli of the LMC. To reduce the uncertainty substantially below 0.1mag will require extensive work on metallicity effects. Non-linearities in the period-luminosity and period-colour relations will also need to be considered as will the need to distinguish unambiguously between fundamental and overtone pulsators.Comment: 26 pages, no figs, to appear in "Stellar Candles for the Extragalactic Distance Scale" Lecture Notes in Physics (Springer) ed. D. Alloin and W. Giere

Carbon-Rich Mira Variables: Kinematics and Absolute Magnitudes

The kinematics of galactic C-Miras are discussed on the basis of the bolometric magnitudes and radial velocities of Papers I and II of this series. Differential galactic rotation is used to derive a zero-point for the bolometric period-luminosity relation which is in satisfactory agreement with that inferred from the LMC C-Miras. We find for the galactic Miras, Mbol = -2.54logP + 2.06 (+/- 0.24), where the slope is taken from the LMC. The mean velocity dispersion, together with the data of Nordstroem et al. and the Padova models, leads to a mean age for our sample of C-Miras of 1.8 +/- 0.4 Gyr and a mean initial mass of 1.8 +/-0.2 solar masses. Evidence for a variation of velocity dispersion with period is found, indicating a dependence of period on age and initial mass, the longer period stars being younger. We discuss the relation between the O- and C-Miras and also their relative numbers in different systems.Comment: 8 pages, 2 figures, accepted for publication in MNRA

San Pedro Meeting on Wide Field Variability Surveys: Some Concluding Comments

This is a written version of the closing talk at the 22nd Los Alamos Stellar pulsation conference on wide field variability surveys. It comments on some of the issues which arise from the meeting. These include the need for attention to photometric standardization (especially in the infrared) and the somewhat controversial problem of statistical bias in the use of parallaxes (and other methods of distance determination). Some major advances in the use of pulsating variables to study Galactic structure are mentioned. The paper includes a clarification of apparently conflicting results from classical Cepheids and RR Lyrae stars in the inner Galaxy and bulge. The importance of understanding non-periodic phenomena in variable stars,particularly AGB variables and RCB stars is stressed, especially for its relevance to mass-loss, in which pulsation may only play a minor role.Comment: Conference on wide field variability surveys: a 21st-century perspective, 8 pages in pres

Enigmas of the Equality Act 2010 - "Three uneasy pieces"

The Equality Act 2010 was designed to simplify as well as unify British discrimination law. While there has been some significant unification, there are a number of areas where it has fallen short with regard to simplification, indeed it has introduced or cemented complexity and confusion. This article examines three such areas concerning two of the protected characteristics (pregnancy/maternity and gender reassignment) and one of the claims (victimisation) within the Equality Act 2010. Subjects: Employment Law; English Law; Human Rights Law & Civil Liberties Keywords: discrimination; Equality Act 2010; victimisation; gender reassignment; pregnancy/ maternity discriminatio

A question of religion or orientation: Hall & Preddy v Bull and the possible effect of the Equality Act 2010

A consideration of the interplay of religion and sexual orientation discrimination following decisions in recent English cases and the potential impact of the Equality Act 2010 on notions of direct and indirect discrimination. Article by James Hand and Pat Feast (School of Law, University of Portsmouth) published in Amicus Curiae – Journal of the Society for Advanced Legal Studies at the Institute of Advanced Legal Studies. The Journal is produced by SALS at the IALS (Institute of Advanced Legal Studies, School of Advanced Study, University of London)