Spatial variations of the 3 micron emission features within nebulae

The 3 micron spectra is presented for the Orion bar region and the Red Rectangle. In both objects spectra were obtained at more than one location, corresponding to different distances from the excitation source. The well known 3.3 and 3.4 micron emission bands are seen in both objects as well as the recently discovered features at 3.46, 3.51, and 3.57 microns in the Orion bar spectra. The spectra show that the relative strengths of the 3 micron emission features vary within the Orion bar. As distance from the exciting star increases, the 3.4 and 3.51 micron features increase, and the 3.46 micron feature decreases in strength, relative to the strong 3.3 micron feature. These are two possible interpretations which are postulated, each of which involves the breaking of bonds by UV radiation, which removes the modes responsible for the 3.4 micron emission near the star. The two possible bond ruptures are the CH bond in small polycyclic aromatic hydrocarbons (PAHs), or the bond to an aliphatic subgroup. It has to be pointed out that neither interpretation appears entirely satisfactory. The vibrational overtone interpretation cannot explain the presence or behavior of the 3.46 micron feature, whereas the laboratory spectra of aliphatic sidegroups contain many more features in the 3 micron region than are observed in the astronomical sources

UK-wide support infrastructure for low frequency noise sufferers ('LFN Network')

The project was set up to meet a need for improved treatment of Low Frequency Noise (LFN) complaints in cases where no noise source could be found. Such cases can be highly distressing for the complainant and difficult to handle by the Environmental Health Officers (EHOs) concerned and so tend to result in disproportionate use of resources. The hypothesis is that, irrespective of the (unknown) cause of the LFN perception, the perception may be lessened through application of techniques specifically adapted from the field of tinnitus and hyperacusis therapy. The aim of the project was therefore to establish, on a trial basis, a national network of treatment centres for sufferers of LFN located within the existing network of tinnitus clinics in the UK. A network of nine audiology centres was established, including eight with a good geographical spread in England and one in Scotland. A treatment protocol, specific to LFN cases, was then developed through discussions with the centres and a referral pathway was also established. Each centre made contact initially with EHOs in one or two local authorities in their vicinity to offer the service which was widened to a larger catchment area if sufficient referrals were not forthcoming. Fourteen subjects took part, eleven of which were referred from EHOs, the remaining three being self-referred. Outcome measures were based on a combination of validated questionnaires for general health, anxiety, depression, tinnitus handicap (with LFN substituted for tinnitus) and hyperacusis, combined with visual-analogue scales specifically developed for LFN to measure the pitch and loudness of the perceived LFN and the associated distress. Qualitative and open questions were also used. Potential benefits to EHOs of being able to make referrals were evaluated by semi-structured telephone interviews in which five EHOs participated. Generally, EHOs were very positive about the service and wanted it to continue. It was clear that LFN cases require significant resources which can be reduced if the referral service is available. Audiologists’ experience was evaluated in a similar way: they were generally willing to take part in the scheme and wanted it to continue and there was a feeling that they would have liked more referrals to get more experience in the use of the protocol. The results showed a mixed picture with some clients, three in particular, showing improved scores across a range of measures with little or no benefit for others and a worsening for one case. The improvement of some clients is positive given the lack of options available for this client group, however, the success of the approach can be considered partial at best. The questionnaire scores indicated that individuals taking part were significantly agitated, stressed and distressed. Those individuals with LFN complaint have a significant clinical need although in the main they were not clinically anxious or depressed. The model proposed of stress and increased auditory gain is a plausible explanation for the symptoms noted in LFN cases. In particular, the involvement of the sympathetic autonomic nervous system, and of the emotional brain, is likely to be a faithful representation of the clinical situation. A number of useful signposts for future development were derived. First, EHOs as well as audiologists should ideally receive training in best practice to help them to handle the particular sensitivities of LFN cases. More awareness and information for GPs is also recommended. A simplification of the referral route, potentially going direct to the audiologist rather than via the GP would also be beneficial. A strong argument for the continuation of the service is that some EHOs are now taking the initiative in contacting audiologists independently to refer LFN complainants in ‘No Noise Found’ cases. Without adequate training things could be made worse but access to a specific LFN protocol and associated training is likely to increase the chances of success significantly. It is recommended that existing guidance for EHOs be extended to include details of audiology services, guidelines for EHOs in making referrals and reference to the LFN treatment protocol. Using data from the study two independent estimates of the incidence rates of LFN cases can be derived. It is estimated that there are up to 160 complainants per year in the NHS corresponding to 0.32 cases per 100 thousand per year. The incidence rate based on referrals made by EHOs is 1.01 per 100 thousand per year within local authorities. It is not known to what extent, if any, these populations overlap

Sub-Micron Diffractive Optical Elements Facilitated by Intrinsic Deswelling of Auxetic Liquid Crystal Elastomers

Diffractive optical elements (DOEs) enable precise control over the direction and filtering of light, making them common components in spectrometers, waveguides, and sensors. There is great interest in tunable and sub-micron diffractive optical elements in flexible photonics and for responsive structural colors. Here this study presents sub-micron tunable diffraction gratings produced by patterning a liquid crystal elastomer (LCE). The intrinsic anisotropic deswelling of the liquid crystal elastomer enables sub-micron (707 nm) pitch structures to be produced from a micron-scale (1040 nm) surface relief grating. Using atomic force microscopy (AFM) and diffraction measurements, a thermal pitch tunability is demonstrated of +212 nm (+31%) or −322 nm (−33%) over a temperature range of 215 °C depending on grating orientation. A mechanical pitch tunability is demonstrate of +1110 nm by applying strains of up to 157% to the liquid crystal elastomer. The height of the diffraction grating is preserved over strain due to the negative Poisson-ratio, or “auxetic”, behavior exhibited by this chosen family of the liquid crystal elastomers. This report opens the possibility of using LCEs to facilitate flexible sub-micron diffractive optical elements, with a high degree of tunability for sensing and structural color applications

Infrared images of reflection nebulae and Orion's bar: Fluorescent molecular hydrogen and the 3.3 micron feature

Images were obtained of the (fluorescent) molecular hydrogen 1-0 S(1) line, and of the 3.3 micron emission feature, in Orion's Bar and three reflection nebulae. The emission from these species appears to come from the same spatial locations in all sources observed. This suggests that the 3.3 micron feature is excited by the same energetic UV-photons which cause the molecular hydrogen to fluoresce

Understanding the determinants and consequences of HIV status disclosure in Manicaland, Zimbabwe: cross-sectional and prospective analyses

Few longitudinal studies have measured trends and effects of disclosure over ART scale-up in general-population samples. We investigated levels, determinants and outcomes of disclosure to relatives and partners in a large general-population cohort in Zimbabwe. Trends in disclosure levels from 2003-2013 were analysed, and multivariable logistic regression was used to identify determinants. Longitudinal analyses were conducted testing associations between disclosure and prevention/treatment-related outcomes. Disclosure to anyone increased from 79% to 100% in men and from 63% to 98% in women from 2003-2008; but declined to 89% in both sexes in 2012-2013. More women than men disclosed to relatives (67.8% versus 44.4%; p<0.001) but fewer women disclosed to partners (85.3% versus 95.0%; p<0.001). In 2012-13, younger age, secondary/higher education, being single, and experience of stigma were associated with disclosure to relatives in both sexes. Partner characteristics and HIV-group attendance were associated with disclosure to partners for women. Reactions to disclosure were generally supportive but less so for females than males disclosing to partners (92.0% versus 97.4%). Partner disclosure was associated with greater social support and treatment adherence in females. To conclude, this study shows disclosure is vital to HIV prevention and treatment, and programmes to facilitate disclosure should be re-invigorated

Excitation and Disruption of a Giant Molecular Cloud by the Supernova Remnant 3C391

Using the IRAM 30-m telescope, we observed the supernova remnant 3C 391 (G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2), and CS(5-4) lines. The ambient molecular gas at the distance (9 kpc) of the remnant comprises a giant molecular cloud whose edge is closely parallel to a ridge of bright non-thermal radio continuum, which evidently delineates the blast-wave into the cloud. We found that in a small (0.6 pc) portion of the radio shell, the molecular line profiles consist of a narrow (2 km/s) component, plus a very wide (> 20 km/s) component. Both spectral components peak within 20" of a previously-detected OH 1720 MHz maser. We name this source 3C 391:BML (broad molecular line); it provides a new laboratory, similar to IC 443 but on a larger scale, to study shock interactions with dense molecular gas. The wide spectral component is relatively brighter in the higher-excitation lines. We interpret the wide spectral component as post-shock gas, either smoothly accelerated or partially dissociated and reformed behind the shock. The narrow component is either the pre-shock gas or cold gas reformed behind a fully dissociative shock. Using the 3 observed CS lines, we measured the temperature, CS column density, and H2 volume density in a dense clump in the parent molecular cloud as well as the wide-line and narrow-line portions of the shocked clump. The physical conditions of the narrow-line gas are comparable to the highest-density clumps in the giant molecular cloud, while the wide-line gas is both warmer and denser. The mass of compressed gas in 3C 391:BML is high enough that its self-gravity is significant, and eventually it could form one or several stars

Polarisation Independent Liquid Crystal Lenses and Contact Lenses using Embossed Reactive Mesogens

Liquid crystal lenses have promise in optical systems owing to their tunability combined with low electrical power, cost, and weight. A good example of such a system is switchable contact lenses for the correction of age‐related presbyopia. Sufficiently large phase modulation can be done using nematic liquid crystals in a meniscus lens configuration. However, the birefringent materials are inherently polarisation dependent, usually requiring orthogonal polarisations to be focussed separately. A novel method is presented for producing polarisation independent lenses based on reactive mesogens. Results are presented for a 2‐level and 3‐level diffractive Fresnel lenses, and the promise of the technique for use in refractive lenses such as contact lenses is discussed

An Exact Calculation of the Energy Density of Cosmological Gravitational Waves

In this paper we calculate the Bogoliubov coefficients and the energy density of the stochastic gravitational wave background for a universe that undergoes inflation followed by radiation domination and matter domination, using a formalism that gives the Bogoliubov coefficients as continous functions of time. By making a reasonable assumption for the equation of state during reheating, we obtain in a natural way the expected high frequency cutoff in the spectral energy density.Comment: 12 pages+5 figures, uuencoded file,DF/IST-2.9

Polarisation Independent Liquid Crystal Lenses using Embossed Reactive Mesogens

Liquid crystal lenses have promise in optical systems owing to their tunability combined with low electrical power, cost and weight. A good example of such a system is switchable contact lenses for the correction of age‐related presbyopia. Large phase modulation can be done using nematic liquid crystals. However, the birefringent materials are inherently polarisation dependent, usually requiring orthogonal polarisations to be focused separately. A novel method is presented for producing polarisation independent lenses based on reactive mesogens