Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe

The Extragalactic Background Light (EBL) includes photons with wavelengths from ultraviolet to infrared, which are effective at attenuating gamma rays with energy above ~10 GeV during propagation from sources at cosmological distances. This results in a redshift- and energy-dependent attenuation of the gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts (GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using photons above 10 GeV collected by Fermi over more than one year of observations for these sources, we investigate the effect of gamma-ray flux attenuation by the EBL. We place upper limits on the gamma-ray opacity of the Universe at various energies and redshifts, and compare this with predictions from well-known EBL models. We find that an EBL intensity in the optical-ultraviolet wavelengths as great as predicted by the "baseline" model of Stecker et al. (2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A. Reimer, L.C. Reye

Referrals from community optometrists to the hospital eye service in Scotland and England

Objectives: This audit assesses communication between community optometrists (COs) and hospital eye service (HES) in Scotland and England. Methods: Optometric referrals and replies were extracted from six practices in Scotland and England. If no reply was found, replies/records were copied from HES records. De-identified referrals, replies and records were audited against established standards, evaluating whether referrals were necessary, accurate and directed to the appropriate professional. The referral rate (RR) and referral reply rate (RRR) were calculated. Results: From 905 de-identified referrals, RR ranged from 2.6 to 8.7%. From COs’ perspective, the proportion of referrals for which they received replies ranged from 37 to 84% (Scotland) and 26 to 49% (England). A total of 88–96% of referrals (Scotland) and 63–76% (England) were seen in the HES. Adjusting for cases when it is reasonable to expect replies, RRR becomes 45–92% (Scotland) and 38–62% (England) with RRR significantly greater in Scotland (P = 0.015). Replies were copied to patients in 0–21% of cases. Referrals were to the appropriate service and judged necessary in ≥90% of cases in both jurisdictions. Accuracy of referral ranged from 89 to 97% (Scotland) and 81 to 98% (England). The reply addressed the reason for referral in 94–100% of cases (Scotland) and 93–97% (England) and was meaningful in 95–100% (Scotland) and 94–99% (England). Conclusions: Despite the interdisciplinary joint statement on sharing patient information, this audit highlights variable standard of referrals and deficits in replies to the referring COs, with one exception in Scotland. Replies from HES to COs are important for patient care, benefitting patients and clinicians and minimising unnecessary HES appointments

Randomised controlled trial of HOYA one-day multifocal contact lenses: The HOMCL trial

Trial design Double-masked crossover RCT (Research Registry: #8136) comparison of a new HOYA one-day disposable multifocal contact lens (HOMCL) with Alcon DAILIES TOTAL1® Multifocal (ADT1). Methods Sixty presbyopic participants from three countries attended for baseline measurements and fitting of both lens types and then for a fortnight completed daily diaries of symptoms with habitual optical correction, and VF-14 questionnaire. Participants collected either HOMCL or ADT1, when the vision was measured again, and they wore this product for a fortnight, completing daily diaries and VF-14. Participants then collected the other type and had vision and symptoms recorded in the same way. Results There were no serious adverse events. Primary outcomes were no significant differences between the lens types in willingness to purchase nor stated preference; no significant differences in the daily symptom ratings of comfort; statistically significant findings with the daily symptom ratings and VF-14 of better near vision with HOMCL and better distance vision with ADT1. Secondary outcomes were better high contrast distance visual acuity with ADT1 (<1 line), better low contrast distance visual acuity with ADT1; faster Wilkins rate of reading test with HOMCL; no significant differences in near visual acuity, wearing time, or number of lenses required during fitting process. Exploratory analyses were better handling scores with ADT1; and some, but not all of the dry eye data indicating better acceptance of HOMCL by patients with relatively dry eyes. For all measures, there were some participants who preferred/performed better with each lens type. Conclusions The differences between the performance of the two products were small. There was a trend in some clinical measurements and the daily diary data and VF-14 questionnaire, for HOMCL to outperform ADT1 for near vision and vice versa for distance vision

The circadian control of retinomotor movements in a teleost fish, the glowlight tetra (Hemigrammus erythrozonus)

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Randomised controlled trial of an accommodative support lens designed for computer users

Purpose: Accommodative support (AS) lenses are a low add progressive addition spectacle lens designed to ease symptoms in computer vision syndrome (CVS). The study aims to investigate if (1) AS lenses improve CVS symptoms; (2) binocular/accommodative functions predict a benefit from AS lenses and (3) wearing AS lenses for six months impacts on binocular/accommodative functions. Methods: Pre-presbyopic adults with symptoms of CVS (Computer Vision Syndrome Questionnaire, CVS-Q©, score ≥ 6) were randomly allocated to wear AS lenses or control single vision (SV) lenses. The CVS-Q© and a battery of optometric tests were applied at baseline and after three and six months. Participants and researchers were masked to participant group. After six months, the SV group were unmasked and changed to AS lenses and one week later asked to choose which they preferred. Results: The change in CVS-Q© scores from baseline to six months did not differ significantly in the two groups. At the end of the one week period, when the control group wore the AS lenses, control group participants were significantly more likely to prefer AS lenses to SV lenses. No optometric functions correlated with the benefit from AS lenses. AS lenses did not have any adverse effects on binocular or accommodative function. Conclusions: In pre-presbyopic adults, there was no greater improvement in CVS-Q© scores in the group wearing AS lenses than in the control group. No adverse effects on optometric function (including accommodation) are associated with wearing AS lenses.Funded by Hoya Holdings NV

Referrals from community optometrists to the hospital eye service in Scotland and England

Abstract Objectives This audit assesses communication between community optometrists (COs) and hospital eye service (HES) in Scotland and England. Methods Optometric referrals and replies were extracted from six practices in Scotland and England. If no reply was found, replies/records were copied from HES records. De-identified referrals, replies and records were audited against established standards, evaluating whether referrals were necessary, accurate and directed to the appropriate professional. The referral rate (RR) and referral reply rate (RRR) were calculated. Results From 905 de-identified referrals, RR ranged from 2.6 to 8.7%. From COs’ perspective, the proportion of referrals for which they received replies ranged from 37 to 84% (Scotland) and 26 to 49% (England). A total of 88–96% of referrals (Scotland) and 63–76% (England) were seen in the HES. Adjusting for cases when it is reasonable to expect replies, RRR becomes 45–92% (Scotland) and 38–62% (England) with RRR significantly greater in Scotland (P = 0.015). Replies were copied to patients in 0–21% of cases. Referrals were to the appropriate service and judged necessary in ≥90% of cases in both jurisdictions. Accuracy of referral ranged from 89 to 97% (Scotland) and 81 to 98% (England). The reply addressed the reason for referral in 94–100% of cases (Scotland) and 93–97% (England) and was meaningful in 95–100% (Scotland) and 94–99% (England). Conclusions Despite the interdisciplinary joint statement on sharing patient information, this audit highlights variable standard of referrals and deficits in replies to the referring COs, with one exception in Scotland. Replies from HES to COs are important for patient care, benefitting patients and clinicians and minimising unnecessary HES appointments. </jats:sec