The recombination spectrum of Carbon II

The determination of the physical parameters of various astrophysical plasmas requires accurate calculation of the radiative and collisional processes involved. The recombination spectrum of Carbon II lends itself to investigating regions such as gaseous nebulae and low temperature stellar winds. In this thesis, a detailed treatment of the recombination processes of CII has been carried out, covering a wide range of temperatures and densities. Accurate photoionisation calculations, using the R-matrix solution to the close coupling equations have been performed. In the process, bound state energy levels have been determined and new weighted oscillator strengths calculated, over a larger range and with a greater accuracy, than had been previously achieved. With careful attention to resonances, which dominate the recombination at low temperatures, recombination coefficients have been evaluated for all states up to n = 15, L = 4. As well as radiative processes, all important collisional processes have been included, creating a full collisional-radiative-cascade model, in order to determine the populations of the states of CII at varying temperatures and densities. Detailed comparison with previous theoretical work has been made. The application of the CII recombination spectrum to the observed spectra of two contrasting astrophysical plasmas such as cold nova shells and Wolf-Rayet stellar winds is considered. The usefulness and applicability of the CII recombination spectrum as a diagnostic tool is ably demonstrated

Cross-sectional study of ethnic differences in the utility of area deprivation measures to target socioeconomically deprived individuals

Area deprivation measures provide a pragmatic tool for targeting public health interventions at socioeconomically deprived individuals. Ethnic minority groups in the UK experience higher levels of socioeconomic deprivation and certain associated diseases than the White population. The aim of this study was to explore ethnic differences in the utility of area deprivation measures as a tool for targeting socioeconomically deprived individuals. We carried out a cross-sectional study using the Health Survey for England 2004. 7,208 participants aged 16-64 years from the four largest ethnic groups in England (White, Indian, Pakistani and Black Caribbean) were included. The main outcome measures were percentage agreement, sensitivity and positive predictive value (PPV) of area deprivation, measured using Index of Multiple Deprivation 2004, in relation to individual socioeconomic position (measured by education, occupation, income, housing tenure and car access). We found that levels of both area and individual deprivation were higher in the Pakistani and Black Caribbean groups compared to the White group. Across all measures, agreement was lower in the Pakistani (50.9-63.4%) and Black Caribbean (61.0-70.1%) groups than the White (67.2-82.4%) group. However, sensitivity was higher in the Pakistani (0.56-0.64) and Black Caribbean (0.59-0.66) groups compared to the White group (0.24-0.38) and PPV was at least as high. The results for the Indian group were intermediate. We conclude that, in spite of lower agreement, area deprivation is better at identifying individual deprivation in ethnic minority groups. There was no evidence that area based targeting of public health interventions will disadvantage ethnic minority groups

Effects of diamagnetic levitation on bacterial growth in liquid

Diamagnetic levitation is a technique that uses a strong, spatially-varying magnetic field to levitate diamagnetic materials, such as water and biological cells. This technique has the potential to simulate aspects of weightlessness, on the Earth. In common with all ground-based techniques to simulate weightlessness, however, there are effects introduced by diamagnetic levitation that are not present in space. Since there have been few studies that systematically investigate these differences, diamagnetic levitation is not yet being fully exploited. For the first time, we critically assess the effect of diamagnetic levitation on a bacterial culture in liquid. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 hours, in a series of experiments to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture. The speed of sedimentation of the bacterial cells to the bottom of the container is considerably reduced. Further experiments and microarray gene analysis show that the growth enhancement is due to greater oxygen availability in the magnetically levitated sample. We demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid, an effect not present in microgravity. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause the liquid to become unstable to convection when the consumption of oxygen by the bacteria generates an oxygen concentration gradient. We propose that this convection enhances oxygen availability by transporting oxygen around the sample. Since convection is absent in space, these results are of significant importance and timeliness to researchers considering using diamagnetic levitation to explore weightless effects on living organisms and a broad range of other topics in the physical and life sciences

A randomised trial of subcutaneous intermittent interleukin-2 without antiretroviral therapy in HIV-infected patients: the UK-Vanguard Study

Objective: The objective of the trial was to evaluate in a pilot setting the safety and efficacy of interleukin-2 (IL-2) therapy when used without concomitant antiretroviral therapy as a treatment for HIV infection. Design and Setting: This was a multicentre randomised three-arm trial conducted between September 1998 and March 2001 at three clinical centres in the United Kingdom. Participants: Participants were 36 antiretroviral treatment naive HIV-1-infected patients with baseline CD4 T lymphocyte counts of at least 350 cells/mm(3). Interventions: Participants were randomly assigned to receive IL-2 at 15 million international units (MIU) per day ( 12 participants) or 9 MIU/day ( 12 participants) or no treatment ( 12 participants). IL-2 was administered by twice-daily subcutaneous injections for five consecutive days every 8 wk. Outcome Measures: Primary outcome was the change from baseline CD4 T lymphocyte count at 24 wk. Safety and plasma HIV RNA levels were also monitored every 4 wk through 24 wk. The two IL-2 dose groups were combined for the primary analysis. Results: Area under curve (AUC) for change in the mean CD4 T lymphocyte count through 24 wk was 129 cells/mm(3) for those assigned IL-2 ( both dose groups combined) and 13 cells/mm(3) for control participants (95% CI for difference, 51.3 - 181.2 cells/mm(3); p = 0.0009). Compared to the control group, significant increases in CD4 cell count were observed for both IL-2 dose groups: 104.2/mm(3) ( p = 0.008) and 128.4 cells/mm(3) ( p = 0.002) for the 4.5 and 7.5 MIU dose groups, respectively. There were no significant differences between the IL-2 (0.13 log(10) copies/ ml) and control (0.09 log(10) copies/ml) groups for AUC of change in plasma HIV RNA over the 24-wk period of follow- up ( 95% CI for difference, - 0.17 to 0.26; p = 0.70). Grade 4 and dose-limiting side effects were in keeping with those previously reported for IL-2 therapy. Conclusions: In participants with HIV infection and baseline CD4 T lymphocyte counts of at least 350 cells/mm(3), intermittent subcutaneous IL-2 without concomitant antiretroviral therapy was well tolerated and produced significant increases in CD4 T lymphocyte counts and did not adversely affect plasma HIV RNA levels