Purpose-To investigate the location and fixation stability of preferred retinal locations (PRLs) in patients with macular disease, and the relationship among areas of abnormal fundus autofluorescence, the PRL and visual sensitivity.Methods-Fifteen patients (15 eyes) were studied. Seven had Stargardt disease, 1 bull's eye maculopathy, 5 age-related macular degeneration, 1 Best disease, and 1 pattern dystrophy. All tested eyes had areas of abnormal fundus autofluorescence. The PRL was evaluated with fundus photography and the Nidek microperimeter. Visual field sensitivity was measured with the Nidek microperimeter.Results-Of the 15 eyes, 4 had foveal and 11 had eccentric fixation. Eccentric PRLs were above the atrophic lesion and their stability did not depend on the degree of eccentricity from the fovea. Visual sensitivity was markedly decreased in locations corresponding to hypofluorescent areas. Sensitivity was not decreased in hyperfluorescent areas corresponding to flecks but was decreased if hyperfluorescence was in the form of dense annuli. Conclusion-EccentricPRLs were in the superior retina in regions of normal fundus autofluorescence. Fixation stability was not correlated with the degree of eccentricity from the fovea. To assess the outcomes of treatment trials it is important to use methods that relate retinal morphology to visual function. KeywordsPreferred retinal location (PRL); microperimetry; fundus autofluorescence; Stargardt disease; agerelated macular degeneration Patients with macular disease and central visual loss affecting the fovea often adopt an eccentric preferred retinal location (PRL). The existence of eccentric PRLs has been known for many years 1 ; however, their characteristics are still not fully understood. Studies have shown that their location can change as a function of the type of macular disease, the luminance level, and the functional task. 2-6 Information as to their location and stability is not only useful for the clinician in planning future treatment of patients with macular disease but also is essential for the correct interpretation of measures of local function such as visual field sensitivity and focal Copyright © Ophthalmic Communications Society, Inc. or multifocal electroretinography. The information may also prove to be an indicator of disease progression. Recently a microperimeter, the Nidek microperimeter (MP-1) (Nidek Technologies Inc., Padova, Italy) has been developed that may be a useful clinical tool for assessing the location and stability of fixation while simultaneously measuring visual field sensitivity. The MP-1 combines fundus tracking microperimetry with color fundus photography. The examiner selects a landmark with high reflectivity on the fundus and stimuli are projected onto the retina in relation to this landmark using an LCD. An automatic eye tracker compensates for eye movements. A color fundus photograph is taken at the end of the examination and a registration technique is used to overlay the perimetric and fixation results on the fu...
Capacity Planning is one of the activities developed by Information Technology departments over the years, it aims at estimating the amount of resources needed to offer a computing service. This activity contributes to achieving high Quality of Service levels and also to pursuing better economic results for companies. In the Cloud Computing context, one plausible scenario is to have Software-as-a-Service (SaaS) providers that build their IT infrastructure acquiring resources from Infrastructure-as-a-Service (IaaS) providers. SaaS providers can reduce operational costs and complexity by buying instances from a reservation market, but then need to predict the number of instances needed in the long-term. This work investigates how important is the capacity planning in this context and how simple business-driven heuristics for long-term capacity planning impact on the profit achieved by SaaS providers. Simulation experiments were performed using synthetic e-commerce workloads. Our analysis show that proposed heuristics increase SaaS provider profit, on average, at 9.6501% per year. Analysing such results we demonstrate that capacity planning is still an important activity, contributing to the increase of SaaS providers profit. Besides, a good capacity planning may also avoid bad reputation due to unacceptable performance, which is a gain very hard to measure.
The study of ceramic drying is theme of several researches today. In most case, this research is realized experimentally, making possible measurements errors that reverberating in data slightly out of the expected, or erroneous. Numerical simulation emerges like a tool that allows the reproduction of experiments using computers and suitable software’s. The use of numerical simulation enables fast changes in boundary conditions and help in the improvement of an unit operation. This paper aims to predict the drying process of an industrial hollow ceramic brick using the liquid diffusion model to describe the behavior of the temperature and moisture content inside the brick and drying kinetics along time, with the help of the Ansys® CFX commercial package. Predicted results of the average moisture content and temperature of the brick were compared with experimental results, and good agreements were obtained. It was verified that regions with smaller thickness dry and heat faster than the others.
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