Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]

BACKGROUND: There is no generally accepted medical or surgical treatment to stop the progressive course of retinitis pigmentosa. Previous studies have suggested lutein as a potential treatment with positive effects on macular pigment density. The objective of this study was to examine the effect of lutein supplementation on preservation of visual function in patients with retinitis pigmentosa (RP) METHODS: In a double-masked randomized placebo-controlled phase I/II clinical trial with a cross-over design, 34 adult patients with RP were randomized to two groups. One group, consisted of 16 participants, received lutein supplementation (10 mg/d for 12 wks followed by 30 mg/d) for the first 24 weeks and then placebo for the following 24 weeks, while the other group included 18 participants for whom placebo (24 weeks) was administered prior to lutein. Visual acuity, contrast sensitivity, and central visual field were measured at different illumination levels at baseline and every week using a PC-based test at home. RESULTS: For visual acuity (VA) at normal illumination level, treatment with lutein reduced logMAR, i.e. improved VA, but this effect was not statistically significant. The changes in normal (100%), low (4%), and very low (0.1%) illumination log CS were not statistically significant (p-values: 0.34, 0.23, and 0.32, respectively). Lutein had a statistically significant effect on visual field (p-value: 0.038) and this effect increased in the model assuming a 6-week delay in effect of lutein. Comparing the development of vision measures against the natural loss expected to occur over the course of 48 weeks, most measures showed reduced decline, and these reductions were significant for normal illumination VA and CS. CONCLUSION: These results suggest that lutein supplementation improves visual field and also might improve visual acuity slightly, although these results should be interpreted cautiously. As a combined phase I and II clinical trial, this study demonstrated the efficacy and safety of lutein supplementation

Crosstalk between DGP branes

If two DGP branes carry U(1) gauge theories and overlap, particles of one brane can interact with the photons from the other brane. This coupling modifies in particular the Coulomb potentials between charges from the same brane in the overlapping regions. The coupling also introduces Coulomb interactions between charges from the different branes which can generate exotic bound states. The effective modification of the fine structure constant in the overlap region generates a trough in signals at the redshift of the overlap region and an increase at smaller or larger redshift, depending on the value of the crosstalk parameter. This implies potentially observable perturbations in the Lyman-alpha forest if our 3-brane overlapped with another 3-brane in a region with redshift z<6. Crosstalk can also affect structure formation by enhancing or suppressing radiative cooling

Quasar environment in the context of large-scale structure at z similar to 0.3

We look at quasar environment in the context of large-scale structure (LSS) - a new approach, giving a more informed interpretation of quasar-galaxy correlations. This paper presents our first results for a sample of z ∼ 0.3 quasars. We use Voronoi tessellation applied in colour (BJ - R) slices for the detection of galaxy clusters and the minimal spanning tree (MST) to delineate the large-scale structure. This new cluster detection method allows us to find reliably galaxy clusters at z &lt; 0.3 from SuperCOSMOS measurements of UK Schmidt Telescope plates. By reconstructing the large-scale structure in a relatively narrow redshift band (0.2 &lt; z &lt; 0.3), we show that quasars follow the large-scale structure traced by galaxy clusters. None of the quasars in our radio-quiet sample is located in the central area of a galaxy cluster. Two quasars, found in a very rich environment, are actually located between two very close galaxy clusters, consistent with results on z ∼ 1 quasars, suggesting that cluster mergers may be involved in one of the quasar formation mechanisms

Relation of radio-quiet quasars to galaxy clusters z<0.3

We investigate whether radio-quiet quasars (RQQs) with z < 0.3 (and predominantly of low luminosity) are located preferentially in specific regions with respect to the centres and boundaries of neighbouring galaxy clusters. This way of characterizing the environment of RQQs differs from previous studies, which relied on the galaxy excess statistics within small radii around the quasars. For the detection of galaxy clusters we use a robust, semiparametric method based on a maximum likelihood estimate applied to Voronoi tessellation and enhanced by a colour-cut approach, allowing boundary determination and redshift estimates. We find that most of the RQQs reside within 3 h -1 Mpc of the centre of a galaxy cluster with comparable redshift and that none of them lies in the core itself. About 20 per cent of the investigated quasars reside between two galaxy clusters, which are possibly at an early stage of merger. Consequently, we suggest that quasars found in rich environments are associated with cluster mergers whereas those found in poorer environments are associated with infall towards a cluster. The information on larger scales provided by our analysis thus allows a clearer interpretation of the diverse environments that have for many years been reported in the literature for smaller scales. We discuss our findings in the context of existing quasar formation models and suggest that at least two formation mechanisms coexist. Additionally, we confirm, using multiple data sets, that low-redshift quasars follow a narrow channel of width ∼10 h -1 Mpc around the large-scale structure (LSS) traced by galaxy clusters, in agreement with the first report of this effect by Söchting, Clowes and Campusano. Such a result, if it applies to quasars at higher redshifts, has the potential to explain the clustering of quasars on scales <10 h -1 Mpc found initially by Shanks et al. The association of the LSS in clusters with the spatial distribution of quasars is not reproduced by samples of narrow emission-line galaxies (NELGs), indicating that the occurrence of NELGs does not require the same environmental conditions as that of quasars

Quasar Spectroscopy with FLAIR

We demonstrate that the multi-object fibre-spectroscopy system 'FLAIR' on the UKST can be used to observe efficiently and effectively the brighter (B < 18.5) high-grade quasar candidates identified from UKST low-dispersion objective-prism plates. The quasar candidiates were selected objectively by the application of AQD (auotmatic quasar detection) to prism paltes that have been digitised using the COSMOS measuring machine. Thirteen high-grade quasar candidates with B <= 18.5 from a prism plate of ESO/SERC survey fileld 296 were observed with a 35-fibre version of FLAIR. From a total observing time of only 3 hours at a resolution of 8.4 angstroms/pixel six candidates were confirmed as quasars and four were identified as stars. The planned upgrade to a thinned, back-illuminated CCD in 1994 should yield a 3-fold increaase in sensitivity and further enhance the capabilities of FLAIR for performing useful spectroscopic observations of quasars of medrate faintness oerlarge areas of sky

Relation of radio-quiet quasars to galaxy clusters at z &lt; 0.3

We investigate whether radio-quiet quasars (RQQs) with z &lt; 0.3 (and predominantly of low luminosity) are located preferentially in specific regions with respect to the centres and boundaries of neighbouring galaxy clusters. This way of characterizing the environment of RQQs differs from previous studies, which relied on the galaxy excess statistics within small radii around the quasars. For the detection of galaxy clusters we use a robust, semiparametric method based on a maximum likelihood estimate applied to Voronoi tessellation and enhanced by a colour-cut approach, allowing boundary determination and redshift estimates. We find that most of the RQQs reside within 3 h -1 Mpc of the centre of a galaxy cluster with comparable redshift and that none of them lies in the core itself. About 20 per cent of the investigated quasars reside between two galaxy clusters, which are possibly at an early stage of merger. Consequently, we suggest that quasars found in rich environments are associated with cluster mergers whereas those found in poorer environments are associated with infall towards a cluster. The information on larger scales provided by our analysis thus allows a clearer interpretation of the diverse environments that have for many years been reported in the literature for smaller scales. We discuss our findings in the context of existing quasar formation models and suggest that at least two formation mechanisms coexist. Additionally, we confirm, using multiple data sets, that low-redshift quasars follow a narrow channel of width ∼10 h -1 Mpc around the large-scale structure (LSS) traced by galaxy clusters, in agreement with the first report of this effect by Söchting, Clowes and Campusano. Such a result, if it applies to quasars at higher redshifts, has the potential to explain the clustering of quasars on scales &lt;10 h -1 Mpc found initially by Shanks et al. The association of the LSS in clusters with the spatial distribution of quasars is not reproduced by samples of narrow emission-line galaxies (NELGs), indicating that the occurrence of NELGs does not require the same environmental conditions as that of quasars