On the existence of optimum cyclic burst-correcting codes

It is shown that for each integer b >= 1 infinitely many optimum cyclic b-burst-correcting codes exist, i.e., codes whose length n, redundancy r, and burst-correcting capability b, satisfy n = 2^{r-b+1} - 1. Some optimum codes for b = 3, 4, and 5 are also studied in detail

Femtosecond Spectroscopy with Vacuum Ultraviolet Pulse Pairs

We combine different wavelengths from an intense high-order harmonics source with variable delay at the focus of a split-mirror interferometer to conduct pump-probe experiments on gas-phase molecules. We report measurements of the time resolution (<44 fs) and spatial profiles (4 {\mu}m x 12 {\mu}m) at the focus of the apparatus. We demonstrate the utility of this two-color, high-order-harmonic technique by time resolving molecular hydrogen elimination from C2H4 excited into its absorption band at 161 nm

Agreement in dry eye management between optometrists and general practitioners in primary health care in the Netherlands

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.clae.2015.03.005 © 2015. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Purpose: To investigate the agreement in dry eye care management between general practitioners (GPs) and optometrists in the Netherlands. Methods: A web-based survey was used to investigate the agreement in symptoms associated with dry eye, causes of developing dry eye, and investigative techniques used in practice, between GPs and optometrists. Additional questions surveyed knowledge of the latest research, and co-management of dry eye disease in primary healthcare. The anonymised questionnaire contained 16 forced-choice questions with Likert scales, and was sent to 1471 general medical practitioners and 870 registered optometrists. The response data was stored on an online database, and was converted directly to text format for analysis using SPSS 21 statistical analysis software. Results: 138 optometrists and 93 GPs responded to the survey (Cronbach α = 0.885, optometrists, and 0.833, GPs). Almost no agreement was found for all the questions: a statistically significant difference (Chi-square p 0.0001), and dry eye symptoms, except for ‘burning sensation of the eye’ and ‘irritation of the eye’ as agreed symptoms, and agreement that dry eye is an age-related disease. Conclusions: As the optometrist and the GP are the gatekeepers for secondary healthcare, the fundamental differences in the methods of investigation and interpretation of dry eye-related symptoms, the possible cause of developing dry eye disease, and the therapy given by GPs and optometrists in the Netherlands, may have a significant impact on consistency of patient care.The authors extend their appreciation to the University of Applied Sciences Utrecht for funding this researc

Identification of the ribosome binding sites of translation initiation factor IF3 by multidimensional heteronuclear NMR spectroscopy

Titrations of Escherichia coli translation initiation factor IF3, isotopically labeled with 15N, with 30S ribosomal subunits were followed by NMR by recording two-dimensional (15N,1H)-HSQC spectra. In the titrations, intensity changes are observed for cross peaks belonging to amides of individual amino acids. At low concentrations of ribosomal subunits, only resonances belonging to amino acids of the C-domain of IF3 are affected, whereas all those attributed to the N-domain are still visible. Upon addition of a larger amount of 30S subunits cross peaks belonging to residues of the N-terminal domain of the protein are also selectively affected. Our results demonstrate that the two domains of IF3 are functionally independent, each interacting with a different affinity with the ribosomal subunits, thus allowing the identification of the individual residues of the two domains involved in this interaction. Overall, the C-domain interacts with the 30S subunits primarily through some of its loops and a-helices and the residues involved in ribosome binding are distributed rather symmetrically over a fairly large surface of the domain, while the N-domain interacts mainly via a small number of residues distributed asymmetrically in this domain. The spatial organization of the active sites of IF3, emerging through the comparison of the present data with the previous chemical modification and mutagenesis data, is discussed in light of the ribosomal localization of IF3 and of the mechanism of action of this factor

Age Related Visual Pathologies among Nursing Home Residents: An Evaluation of Light Conditions and Recording in Client Files

Objective: Reflection on visual problems in nursing homes. Data Sources: Eye examinations, documented visual problems and illuminance levels. Study design: The optometric examinations and recorded visual problems were combined with illuminance data. Data collection: In seven nursing homes, 259 residents underwent an optometric examination. Their client records were analyzed for information regarding visual functioning. The illuminance data were ranked to set the quality of the lighting conditions. Principal findings: 50% of the referred residents had problems with cataracts, retinal problems (21%), suspected glaucoma (13%), and other pathologies (16%). The information was not current in 56% of the records. The quality of lighting conditions was low or moderate. Conclusion: The finding of poor lighting conditions in nursing homes in combination with a high prevalence of visual problems (with cataract found to be the most common age related pathology), stretches the need of enhanced awareness of eye care by professional caregivers

The effect of sodium fluorescein on anterior eye surface measurements

Purpose During image acquisition, certain topographers require the addition of sodium fluorescein (NaFl) dye to the tear film. This study investigates the effect of NaFl dye on corneal topography and tear surface quality. Method The E300 corneal topographer (Medmont International Pty Ltd., Victoria, Australia) was used to measure ocular surface topography and quality of 57 eyes of 57 healthy individuals without dry eye symptoms, age 35.1 ± 15.2 years (mean ± standard deviation) ranging between 19 and 65 years. The mean of three simulated keratometry values, a variety of corneal shape descriptors, and Tear Film Surface Quality (TFSQ) were measured under three different conditions; without NaFl (baseline), with the addition of a single dose NaFl, and using a double dose of NaFl. Results Compared to baseline, the Inferior-Superior (IS) index decreased significantly after a single dose (P = 0.034) or double dose of NaFl (P = 0.030). The corneal surface was significantly more regular without NaFl (P = 0.003) or one insertion of NaFl (P = 0.024) when compared to two doses of NaFl. There was no association with age, or dry eye signs or symptoms on the variance observed in any of the indices between baseline, intervention I, and intervention II (P > 0.05). Agreement between corneal surface indices reduced following the addition of NaFl. Conclusion In comparison to measurements taken without an ocular dye, one dose of NaFl resulted in increased reliability and consistency in corneal topography measurements using the E300 topographer, but 2 doses decreased reliability and consistency. Practitioners ought to be aware that tear film surface regularity and inferior-superior corneal power changed significantly following the addition of NaFl in those with healthy corneas. Its effect in diseased corneas is unknown

Comparison between subjective fluorescein breakup time and automated tear breakup time measurements using the E300 corneal topographer

Purpose Comparison of invasive fluorescein tear film breakup time (FBUT) and the automated measurement of tear film stability known as Tear Film Surface Quality (TFSQ) breakup time using placido disc videokeratography measured with and without fluorescein sodium (NaFl). Method In 57 eyes of 57 subjects (males n=23, females n=34), FBUT using a single dose of NaFl was measured three times and automated TSFQ breakup time was measured twice under two different conditions: non-invasively (without NaFl), and using a single dose NaFl, using the E300 corneal topographer (Medmont International Pty Ltd., Victoria, Australia). Mean age (± SD) was 35.1±15.2 years ranging from 19 to 65 years. There was no history of ocular diseases, contact lens wear, or previously diagnosed dry eye. Subjects were grouped by age (12 [n=21]). Results There were no significant differences between the three consecutive measures of FBUT (p=0.62), two measures of TFSQ breakup time without NaFl (p=0.67) or with NaFl (p=0.96). There were strong significant correlations between TFSQ without and with NaFl (r=0.709, p<0.0005) and moderate significant correlations between the FBUT and TFSQ breakup time without NaFl (r=0.583, p<0.0005) and with NaFl (r=0.432, p=0.001). Average FBUT was significantly shorter (8.1 ± 6.9 sec) compared to TFSQ breakup time without NaFl (12.6 ± 12.9 sec) and with NaFl (13.6 ± 12.6 sec; p=0.002, partially eta squared=0.21), irrespective of age group (p=0.36) or gender (p=0.60) or OSDI score (p=0.67). Conclusion Automated TFSQ break up time measured with the Medmont E300 topographer is repeatable when measured with and without the addition of NaFl dye; however, the TFSQ break up time is overall significantly increased compared to subjective FBUT. Both measures of tear breakup time are therefore not interchangeable

The effect of fluorescein sodium volume on anterior eye surface measurements using the Medmont corneal topographer

Purpose This study investigates the effect of fluorescein sodium (NaFl) volume on the regularity of the anterior eye surface using the Medmont corneal topographer measurements. Method The simulated keratometry values (flat = Kf; steep = Ks), Inferior Superior Index (ISI), Surface Asymmetry Index (SAI), and Surface Regularity Index (SRI) measurements, using the E300 corneal topographer (Medmont International Pty Ltd., Victoria, Australia), were taken three times under three different conditions: baseline (without NaFl), including a single dose NaFl, and a double dose NaFl. Of the 57 participants (males n=23, females n=34) only the right eye was included. Mean age (± SD) was 35.1±15.2 years (range 19 to 65 years); grouped by age (<40 years [n=34] versus ≥40 years [n=23]). There was no history of ocular diseases, contact lens wear, or previously diagnosed dry eye. Results At baseline, there were no significant differences between the three consecutive measures of Kf (p=0.30), Ks (p=0.71), ISI (p=0.10), SAI (p=0.53) and SRI (p=0.34). This was comparable to any amount of NaFl (p>0.05). Median ISI values following the addition of 1 or 2 doses NaFl significantly decreased compared to baseline (both z=3.2, effect size 0.43; p=0.001), irrespective of age group (p=0.74). No significant differences between the three conditions for any other parameter (p>0.05) were found. The intraclass correlation coefficient (ICC) improved for Kf (0.99), Ks (0.99) and SRI (0.60) with one dose of NaFl, compared to baseline or 2 doses of NaFl. For IS and SAI, ICC was most reliable without NaFl (0.85 and 0.77 respectively). Conclusion One drop NaFl increases reliability in corneal topography and regularity measurements using the E300 topographer. Corneal asymmetry measurements (IS and SAI) are more reliable without any ocular dye. It is possible that the addition of NaFl enhances tear film reflection during topography measurements, but the addition of a liquid solution decreases symmetry