Constraining Isocurvature Initial Conditions with WMAP 3-year data

We present constraints on the presence of isocurvature modes from the temperature and polarization CMB spectrum data from the WMAP satellite alone, and in combination with other datasets including SDSS galaxy survey and SNLS supernovae. We find that the inclusion of polarization data allows the WMAP data alone, as well as in combination with complementary observations, to place improved limits on the contribution of CDM and neutrino density isocurvature components individually. With general correlations, the upper limits on these sub-dominant isocurvature components are reduced to ~60% of the first year WMAP results, with specific limits depending on the type of fluctuations. If multiple isocurvature components are allowed, however, we find that the data still allow a majority of the initial power to come from isocurvature modes. As well as providing general constraints we also consider their interpretation in light of specific theoretical models like the curvaton and double inflation.Comment: 8 pages, 7 figures. Revised Sec 4 and Figs 3-4 post-publication to correct an error for models with varying isocurvature spectral inde

Explaining variation in GP referral rates for x-rays for back pain

BACKGROUND: Despite the availability of clinical guidelines for the management of low back pain (LBP), there continues to be wide variation in general practitioners' (GPs') referral rates for lumbar spine x-ray (LSX). This study aims to explain variation in GPs' referral rates for LSX from their accounts of the management of patients with low back pain. METHODS: Qualitative, semi-structured interviews with 29 GPs with high and low referral rates for LSX in North East England. Thematic analysis used constant comparative techniques. RESULTS: Common and divergent themes were identified among high- and low-users of LSX. Themes that were similar in both groups included an awareness of current guidelines for the use of LSX for patients with LBP and the pressure from patients and institutional factors to order a LSX. Differentiating themes for the high-user group included: a belief that LSX provides reassurance to patients that can outweigh risks, pessimism about the management options for LBP, and a belief that denying LSX would adversely affect doctor-patient relationships. Two specific differentiating themes are considered in more depth: GPs' awareness of their use of lumbar spine radiology relative to others, and the perceived risks associated with LSX radiation. CONCLUSION: Several key factors differentiate the accounts of GPs who have high and low rates of referral for LSX, even though they are aware of clinical guideline recommendations. Intervention studies that aim to increase adherence to guideline recommendations on the use of LSX by changing the ordering behaviour of practitioners in primary care should focus on these factors

Cognates, competition and control in bilingual speech production

If an individual speaks more than one language, there are always at least two ways of verbalising any thought to be expressed. The bilingual speaker must then have a means of ensuring that their utterances are produced in the desired language. However, prominent models of speech production are based almost exclusively on monolingual considerations and require substantial modification to account for bilingual production. A particularly important feature to be explained is the way bilinguals control the language of speech production: for instance, preventing interference from the unintended language, and switching from one language to another. One recent model draws a parallel between bilinguals control of their linguistic system and the control of cognitive tasks more generally. The first two experiments reported in this thesis explore the validity of this model by comparing bilingual language switching with a monolingual switching task, as well as to the broader task-switching literature. Switch costs did not conform to the predictions of the task-set inhibition hypothesis in either experiment, as the paradoxical asymmetry of switch costs was not replicated and some conditions showed benefits, rather than costs, for switching between languages or tasks. Further experiments combined picture naming with negative priming and semantic competitor priming paradigms to examine the role of inhibitory and competitive processes in bilingual lexical selection. Each experiment was also conducted in a parallel monolingual version. Very little negative priming was evident when speaking the second language, but the effects of interlingual cognate status were pronounced. There were some indications of cross-language competition at the level of lexical selection: participants appeared unable to suppress the irrelevant language, even when doing so would make the task easier. Across all the experiments, there was no evidence for global inhibition of the language-not-in-use during speech production. Overall results were characterised by a remarkable flexibility in the mechanisms of bilingual control. A striking dissociation emerged between the patterns of results for cognate and non-cognate items, which was reflected throughout the series of experiments and implicates qualitative differences in the way these lexical items are represented and interconnected

Snapshot of Internet Innovation: Using e-Philanthropy to Expand Volunteering, Giving and Community Building

A report on the 3rd e-Philanthropy Conference in McLean, Virginia, USA, exploring the strategic issues and promising practices of the Internet to increase various forms of civic engagement including giving, volunteering, and community buildin

Graduates’ orientations to Higher Education and their retrospective experiences of teaching and learning

In this article, we sought a relation between orientation to higher education and curricular experiences, and elucidated the nature of transformative curricular experiences. Twenty-four graduates from humanities and science degrees in the year 2000 were interviewed approximately five years later to obtain their retrospective views on the purpose of higher education, as well as their undergraduate experiences of teaching and learning. Drawing on phenomenographic principles, four orientations to higher education were generated. Four participant cases are analyzed, representing each orientation to higher education. In the ‘gaining a qualification’ orientation, graduates valued being told what to learn, as well as learning practical skills. For the ‘preparation for a job’ orientation, graduates wanted lecturers who were good at conveying information, but they also valued project work, having some autonomy over learning and practical applications. In the ‘developing skills and learning how to think’ orientation, graduates valued being challenged and learning in groups, but also wanted to learn professional skills. In the ‘growing as an individual’ orientation, graduates valued being challenged, gaining different perspectives, developing critical thinking, learning about theory, interacting with lecturers, research, and study for its own sake. Some curricular experiences transformed thinking about the purpose of higher education, including learning through discussion in small groups, authentic learning tasks including inquiry-based assignments, exercises in developing critical thinking, opportunities to interact with teachers, opportunities to develop practical skills, experiencing different cultures and personal growth through lifestyle and social experiences. Our research has implications for advising students, as well as for teachers aiming to encourage a deep approach to learning

Light-Element Abundance Variations at Low Metallicity: the Globular Cluster NGC 5466

We present low-resolution (R~850) spectra for 67 asymptotic giant branch (AGB), horizontal branch and red giant branch (RGB) stars in the low-metallicity globular cluster NGC 5466, taken with the VIRUS-P integral-field spectrograph at the 2.7-m Harlan J. Smith telescope at McDonald Observatory. Sixty-six stars are confirmed, and one rejected, as cluster members based on radial velocity, which we measure to an accuracy of 16 km s-1 via template-matching techniques. CN and CH band strengths have been measured for 29 RGB and AGB stars in NGC 5466, and the band strength indices measured from VIRUS-P data show close agreement with those measured from Keck/LRIS spectra previously taken of five of our target stars. We also determine carbon abundances from comparisons with synthetic spectra. The RGB stars in our data set cover a range in absolute V magnitude from +2 to -3, which permits us to study the rate of carbon depletion on the giant branch as well as the point of its onset. The data show a clear decline in carbon abundance with rising luminosity above the luminosity function "bump" on the giant branch, and also a subdued range in CN band strength, suggesting ongoing internal mixing in individual stars but minor or no primordial star-to-star variation in light-element abundances.Comment: 10 pages, emulateapj format, AJ accepte

Delayed Recombination and Standard Rulers

Measurements of Baryonic Acoustic Oscillations in galaxy surveys have been recognized as a powerful tool for constraining dark energy. However, this method relies on the knowledge of the size of the acoustic horizon at recombination derived from Cosmic Microwave Background Anisotropy measurements. This estimate is typically derived assuming a standard recombination scheme; additional radiation sources can delay recombination altering the cosmic ionization history and the cosmological inferences drawn from CMB and BAO data. In this paper we quantify the effect of delayed recombination on the determination of dark energy parameters from future BAO surveys such as BOSS and WFMOS. We find the impact to be small but still not negligible. In particular, if recombination is non-standard (to a level still allowed by CMB data), but this is ignored, future surveys may incorrectly suggest the presence of a redshift dependent dark energy component. On the other hand, in the case of delayed recombination, adding to the analysis one extra parameter describing deviations from standard recombination, does not significantly degrade the error-bars on dark energy parameters and yields unbiased estimates.Comment: 8 pages, 5 figure