The effect of ocular nutritional supplements on macular pigment optical density

This thesis describes the investigation of the effects of ocular supplements with different levels of nutrients on the macular pigment optical density (MPOD) in participants with healthy eyes. Abstract A review of the literature highlighted that ocular supplements are produced in various combinations of nutrients and concentrations. The ideal concentrations of nutrients such as lutein (L) have not been established. It was unclear whether different stages of eye disease require different concentrations of key nutrients, leading to the design of this study. The primary aim was to determine the effects of ocular supplements with different concentrations of nutrients on the MPOD of healthy participants. The secondary aim was to determine L and zeaxanthin (Z) intake at the start and end of the study through completion of food diaries. The primary study was split into two experiments. Experiment 1 was an exploratory study to determine sample size and experiment 2 the main study. Statistical power was calculated and a sample size of 38 was specified. Block stratification for age, gender and smoking habit was applied and from 101 volunteers 42 completed the study, 31 with both sets of food diaries. Four confounders were accounted for in the design of the study; gender, smoking habit, age and diet. Further factors that could affect comparability of results between studies were identified during the study and were not monitored; ethnicity, gastro-intestinal health, alcohol intake, body mass index and genetics. Comparisons were made between the sample population and the Sheffield general population according to recent demographic results in the public domain. Food diaries were analysed and shown to have no statistical difference when comparing baseline to final results. The average L and Z intake for the 31 participants who returned both sets of food diaries was initially 1.96mg and 1.51mg for the final food diaries. The effect of the two ocular supplements with different levels of xanthophyll (6mg lutein/zeaxanthin and 10mg lutein only) on MPOD was not significantly different over a four-month period.

Estimation of ocular volume from axial length

Background/aims - To determine which biometric parameters provide optimum predictive power for ocular volume. Methods - Sixty-seven adult subjects were scanned with a Siemens 3-T MRI scanner. Mean spherical error (MSE) (D) was measured with a Shin-Nippon autorefractor and a Zeiss IOLMaster used to measure (mm) axial length (AL), anterior chamber depth (ACD) and corneal radius (CR). Total ocular volume (TOV) was calculated from T2-weighted MRIs (voxel size 1.0 mm3) using an automatic voxel counting and shading algorithm. Each MR slice was subsequently edited manually in the axial, sagittal and coronal plane, the latter enabling location of the posterior pole of the crystalline lens and partitioning of TOV into anterior (AV) and posterior volume (PV) regions. Results - Mean values (±SD) for MSE (D), AL (mm), ACD (mm) and CR (mm) were −2.62±3.83, 24.51±1.47, 3.55±0.34 and 7.75±0.28, respectively. Mean values (±SD) for TOV, AV and PV (mm3) were 8168.21±1141.86, 1099.40±139.24 and 7068.82±1134.05, respectively. TOV showed significant correlation with MSE, AL, PV (all p<0.001), CR (p=0.043) and ACD (p=0.024). Bar CR, the correlations were shown to be wholly attributable to variation in PV. Multiple linear regression indicated that the combination of AL and CR provided optimum R2 values of 79.4% for TOV. Conclusion - Clinically useful estimations of ocular volume can be obtained from measurement of AL and CR.

Structural design of contact lens-based drug delivery systems; in vitro and in vivo studies of ocular triggering mechanisms

This study identifies and investigates the potential use of in-eye trigger mechanisms to supplement the widely available information on release of ophthalmic drugs from contact lenses under passive release conditions. Ophthalmic dyes and surrogates have been successfully employed to investigate how these factors can be drawn together to make a successful system. The storage of a drug-containing lens in a pH lower than that of the ocular environment can be used to establish an equilibrium that favours retention of the drug in the lens prior to ocular insertion. Although release under passive conditions does not result in complete dye elution, the use of mechanical agitation techniques which mimic the eyelid blink action in conjunction with ocular tear chemistry promotes further release. In this way differentiation between passive and triggered in vitro release characteristics can be established. Investigation of the role of individual tear proteins revealed significant differences in their ability to alter the equilibrium between matrix-held and eluate-held dye or drug. These individual experiments were then investigated in vivo using ophthalmic dyes. Complete elution was found to be achievable in-eye; this demonstrated the importance of that fraction of the drug retained under passive conditions and the triggering effect of in-eye conditions on the release process. Understanding both the structure-property relationship between drug and material and in-eye trigger mechanisms, using ophthalmic dyes as a surrogate, provides the basis of knowledge necessary to design ocular drug delivery vehicles for in-eye release in a controllable manner.

Queue Length Simulations in a Finite Single-line Queueing System with Repeated Calls

2000 Mathematics Subject Classification: 60K25.

Ocular dominance and handedness in golf putting

Purpose: In golf, the impact of eye-hand dominance on putting performance has long been debated. Eye-hand dominance is thought to impact how golfers judge the alignment of the ball with the target and the club with the ball, as well as how golfers visualize the line of the putt when making decisions about the force needed to hit the ball. Previous studies have all measured ocular dominance in primary gaze only, despite golfers spending a significant amount of their time in a putting stance (bent at the hips, head tilted down). Thus, the purpose of this study was to assess ocular dominance in both primary gaze (aligning the ball with the target) and putting gaze (addressing the ball and aligning the club). Methods: This study investigatedmeasuring pointing oculardominance in both primary and putting gaze positions on 31 golfers (14 amateur, 7 club professionals, and 10 top professionals). All playerswere right-handed golfers, although one reported having no hand dominance and one reported being strongly left hand dominant. Results: The results showed that (1) primary and putting gaze ocular dominances are not equal, nor are they predictive of each other; (2) themagnitude of putting ocular dominance is significantly less than themagnitude of primary gaze ocular dominance; (3) ocular dominance is not correlated with handedness in either primary or putting gaze; and (4) eye-hand dominance is not associated with increased putting skill, although ocular dominance may be associated with increased putting success. Conclusions: It is important that coaches assess golfers' ocular dominance in both primary and putting gaze positions to ensure they have the most accurate information upon which to base their vision strategy decisions.

Investigating ocular allergy:can we determine a better measurement?

Objective: Ocular allergy is a broad group of allergic conditions involving inflammation of the conjunctiva and the most common forms are seasonal allergic conjunctivitis (SAC; 90% of cases) and perennial allergic conjunctivitis (PAC; 5% of cases). The main symptom is ocular itching caused by mast cell degranulation leading to the release of histamine and other mediators such as tryptase. Tryptase is a neutral protease that is selectively concentrated in the secretory granules of human mast cells and has been shown to be a sensitive and specific marker of type I hypersensitivity reaction. The objective was to ascertain the best assay method for determining the tryptase levels in tear samples and whether this can be used to determine the efficacy of non-pharmacological treatments compared to no treatment or their combined effect with anti-allergic medication for SAC and PAC. Method: Thirty patients with a history of SAC were recruited into a randomised blind study during winter months when all the patients were asymptomatic. Suitability was determined by skin prick and conjunctival provocation tests. Patients were randomly assigned to either a non-pharmacological or a pharmacological Intervention group and received each test condition assigned to their group in a randomly assigned order. Symptoms were provoked by exposure to pollen in an environmental test chamber where the temperature, humidity and grass pollen levels were set to a high pollen count day. Tear samples were taken set intervals during the visit and then processed by enzyme linked immunosorbent assay (ELISA) for the detection of tryptase levels. Preliminary results: Results are still being analysed but the preliminary optimisation experiments tested four different ELISA systems; two indirect assays and two capture ‹sandwich› assays. The results suggest that in both sandwich assay systems non-specific binding occurred which could not be easily overcome. The indirect assay systems both showed specific reactions, and the sensitivity achieved was greater with the monoclonal than the polyclonal antibody. Using these findings the indirect assay system was optimised to provide a standardised system for measuring tryptase. Initial trials using human tear samples displayed tryptase levels between 23.1 and 175.1 ng/ml; levels which fall within the anticipated range for patients with SAC. Further statistical work is needed to determine whether tryptase levels vary between the treatments 75.

Use of the retinal vessel analyzer in ocular blood flow research

The present article describes a standard instrument for the continuous online determination of retinal vessel diameters, the commercially available retinal vessel analyzer. This report is intended to provide informed guidelines for measuring ocular blood flow with this system. The report describes the principles underlying the method and the instruments currently available, and discusses clinical protocol and the specific parameters measured by the system. Unresolved questions and the possible limitations of the technique are also discussed. © 2009 Acta Ophthalmol.

Ocular biotribology and the contact lens:Surface interactions and ocular response

Biotribology is essentially the study of friction, lubrication and wear in biological systems. The area has been widely studied in relation to the behaviour of synovial joints and the design and behaviour of hip joint prostheses, but only in the last decade have serious studies been extended to the eye. In the ocular environment - as distinct from articular joints - wear is not a major factor. Both lubrication and friction are extremely important, however; this is particularly the case in the presence of the contact lens, which is a medical device important not only in vision correction but also as a therapeutic bandage for the compromised cornea. This chapter describes the difficulty in replicating experimental conditions that accurately reflect the complex nature of the ocular environment together with the factors such as load and rate of travel of the eyelid, which is the principal moving surface in the eye. Results obtained across a range of laboratories are compared.

The ageing ocular surface:challenges for biomaterials design and function

Changing demographics and in particular an increasingly ageing population, in combination with improved longevity, will have a major impact on changing the face of human diseases and likewise the demand for appropriate biomaterials. The ocular surface is a multifaceted system that combines to create a unique mucosal surface, which includes the cornea, conjunctiva, sclera and lids of the eye. Physical parameters such as the eyelids and eyelashes, combined with the numerous secretory glands that produce the complex tear film, act together to protect and maintain the cornea. Unfortunately an ageing tear film and lacrimal functional unit can lead to impairment of this magnificently orchestrated structure. No single mechanism or modification is responsible but, whatever the cause, the consequence is a reduction in tear stability. An uncompromised tear film is fundamental to a healthy ocular surface. In the face of progressively changing demographics and consequent requirements for medical intervention and medical device developments, it is important to understand what effects the ageing process has on these anterior ocular structures.

Végtelen sokszor ismételt kiszerződés (Infinitely repeated outsourcing)

A cikk a kormányzat és a vállalat közti végtelen sokszor ismételt kiszerződésekkel foglalkozik. Vizsgálati eszköztárát a nem teljes szerződések elméletéből kölcsönzi. A szakirodalmat felhasználva megmutatja, hogy létezik olyan fenyegetési stratégia, köznapi szóhasználattal az adott szabályok esetén mindkét fél számára saját érdekében betartandó stratégia, ahol mind a vállalat, mind a kormányzat beruházásának értéke a társadalmilag optimális nagyság. Bebizonyítja, hogy annál valószínűbb, hogy mind a kormányzat, mind a vállalat a társadalmilag optimális beruházási szintet valósítja meg, minél nagyobb annak az esélye, hogy az adott vállalat kapja meg a következő periódusban is az ismétlődő munkafeladatot. Felhívja a figyelmet a szabályozó felelősségére az újabb szerződés valószínűségének indirekt meghatározásában. ____ The paper analyses the in¯nitely repeated contracts between the government and a firm. Methods from the incomplete contract theory are used for this analysis. Based on the literature, it is shown that there exist a trigger strategy, when both the government and the firm deploy the socially optimal amount of investment. The paper proves that the greater the chance that an excellently accomplished firm receives a new contract the higher is the probability that both actors' investments are on the socially optimal level. The regulator has a great liability in establishing indirectly the chance of receiving a new contract opportunity.

Predicting jurors' decisions: The effects of repeated expression and forewarning in civil voir dire

To help lawyers uncover jurors' attitudes and predict verdict, litigation experts recommend that attorneys encourage jurors to repeatedly express their attitudes during voir dire. While social cognitive literature has established that repeated expression of attitudes increases accessibility and behavior predictability, the persuasive twist on the method exercised in trials deserves empirical investigation. Only one study has examined the use of repeated expression within a legal context with the results finding that the tactic increased accessibility, but did not influence the attitude verdict relationship. This dissertation reexamines the ability of civil attitudes to predict verdict in a civil trial and investigates the use of repeated expression as a persuasive tactic utilized by both parties (Plaintiff and Defense) within a civil voir dire in an attempt to increase attitudinal strength, via accessibility, and change attitudes to better predict verdict. This project also explores potential moderators, repetition by the opposing party and the use of a forewarning, to determine their ability to counter the effects of repeated expression on attitudes and verdict.^ This dissertation project asked subjects to take on the role of jurors in a civil case. During the voir dire questioning session, the number of times the participants were solicited to express their attitudes towards litigation crisis by both parties was manipulated (one vs. five). Also manipulated was the inclusion of a forewarning statement from the plaintiff, within which mock jurors were cautioned about the repeated tactics that the defense may use to influence their attitudes. Subsequently, participants engaged in a response latency task which measured the accessibility of their attitudes towards various case-related issues. After reading a vignette of a fictitious personal injury case, participants rendered verdict decisions and responded to an attitude evaluation scale. Exploratory factor analyses, Probit regressions, and path analyses were used to analyze the data. Results indicated that the act of repeated expression influenced both the accessibility and value of litigation crisis attitudes thus increasing the attitude-verdict relationship, but only when only one party engaged in it. Furthermore, the forewarning manipulation did moderate the effect of repeated expression on attitude change and verdict, supporting our hypothesis.^

Effects of repeated readings on reading abilities of English language learners with specific learning disabilities

This study investigated the effects of repeated readings on the reading abilities of 4, third-, fourth-, and fifth-grade English language learners (ELLs) with specific learning disabilities (SLD). A multiple baseline probe design across subjects was used to explore the effects of repeated readings on four dependent variables: reading fluency (words read correctly per minute; wpm), number of errors per minute (epm), types of errors per minute, and answer to literal comprehension questions. Data were collected and analyzed during baseline, intervention, generalization probes, and maintenance probes. Throughout the baseline and intervention phases, participants read a passage aloud and received error correction feedback. During baseline, this was followed by fluency and literal comprehension question assessments. During intervention, this was followed by two oral repeated readings of the passage. Then the fluency and literal comprehension question assessments were administered. Generalization probes followed approximately 25% of all sessions and consisted of a single reading of a new passage at the same readability level. Maintenance sessions occurred 2-, 4-, and 6-weeks after the intervention ended. The results of this study indicated that repeated readings had a positive effect on the reading abilities of ELLs with SLD. Participants read more wpm, made fewer epm, and answered more literal comprehension questions correctly. Additionally, on average, generalization scores were higher in intervention than in baseline. Maintenance scores were varied when compared to the last day of intervention, however, with the exception of the number of hesitations committed per minute maintenance scores were higher than baseline means. This study demonstrated that repeated readings improved the reading abilities of ELLs with SLD and that gains were generalized to untaught passages. Maintenance probes 2-, 4-, and 6- weeks following intervention indicated that mean reading fluency, errors per minute, and correct answers to literal comprehensive questions remained above baseline levels. Future research should investigate the use of repeated readings in ELLs with SLD at various stages of reading acquisition. Further, future investigations may examine how repeated readings can be integrated into classroom instruction and assessments.

Comparison of repeated and two non-repeated readings conditions on reading abilities of students with emotional and/or behavioral disabilities

Students with emotional and/or behavioral disorders (EBD)present considerable academic challenges along with emotional and/or behavioral problems. In terms of reading, these students typically perform one-to-two years below grade level (Kauffman, 2001). Given the strong correlation between reading failure and school failure and overall success (Scott & Shearer-Lingo, 2002), finding effective approaches to reading instruction is imperative for these students (Staubitz, Cartledge, Yurick, & Lo, 2005). This study used an alternating treatments design to comparethe effects of three conditions on the reading fluency, errors, and comprehension of four, sixth-grade students with EBD who were struggling readers. Specifically, the following were compared: (a) Repeated readings in which participants repeatedly read a passage of about 100-150 words, three times, (b) Non-repeated readings in which participants sequentially read an original passage of about 100-150 words once, and (c) Equivalent non-repeated readings in which participants sequentially read a passage of about 300-450 words, equivalent to the number of words in the repeated readings condition. Also examined were the effects of the three repeated readings practice trials per sessions on reading fluency and errors. The reading passage difficulty and length established prior to commencing were used for all participants throughout the standard phase. During the enhanced phase, the reading levels were increased 6 months for all participants, and for two (the advanced readers), the length of the reading passages was increased by 50%, allowing for comparisons under more rigorous conditions. The results indicate that overall repeated readings had the best outcome across the standard and enhanced phases for increasing readers’ fluency, reducing their errors per minute, and supporting fluency answers to literal comprehension questions correctly as compared to non-repeated and equivalent non-repeated conditions. When comparing nonrepeated and equivalent non-repeated readings,there were mixed results. Under the enhanced phases, the positive effects of repeated readings were more demonstrative. Additional research is needed to compare the effects of repeated and equivalent non-repeated readings across other populations of students with disabilities or varying learning styles. This research should include collecting repeated readings practice trial data for fluency and errors to further analyze the immediate effects of repeatedly reading a passage.

The Effects of Repeated Readings on Reading Abilities of English Language Learners with Specific Learning Disabilities

This study evaluates the effects of repeated readings on the reading fluency and comprehension of 4 third through fifth grade English Language Learners (ELLs) with Specific Learning Disabilities (SLD). The results indicate gains in fluency, a decrease in errors, and an increase in correct answers to literal comprehension questions.

Pairing Repeated Reading and Systematic Error Correction: Impact on Fluency of 18 Year Old Students on a Small Caribbean Island

This study investigates the impact of a combined treatment of Systematic Error Correction and Repeated Reading on reading rate and errors for 18 year olds with undiagnosed reading difficulties on a Caribbean Island. In addition to direct daily measures of reading accuracy, the Reading Self Perception Scale was administered to determine whether the intervention was associated with changes in the way the student perceives himself as a reader.