Corneal Biomechanics, Retinal Nerve Fiber Layer, and Optic Disc in Children

Purpose: To evaluate the possible associations between corneal biomechanical parameters, optic disc morphology, and retinal nerve fiber layer (RNFL) thickness in healthy white Spanish children. Methods: This cross-sectional study included 100 myopic children and 99 emmetropic children as a control group, ranging in age from 6 to 17 years. The Ocular Response Analyzer was used to measure corneal hysteresis (CH) and corneal resistance factor. The optic disc morphology and RNFL thickness were assessed using posterior segment optical coherence tomography (Cirrus HD-OCT). The axial length was measured using an IOLMaster, whereas the central corneal thickness was measured by anterior segment optical coherence tomography (Visante OCT). Results: The mean (±SD) age and spherical equivalent were 12.11 (±2.76) years and −3.32 (±2.32) diopters for the myopic group and 11.88 (±2.97) years and +0.34 (±0.41) diopters for the emmetropic group. In a multivariable mixed-model analysis in myopic children, the average RNFL thickness and rim area correlated positively with CH (p = 0.007 and p = 0.001, respectively), whereas the average cup-to-disc area ratio correlated negatively with CH (p = 0.01). We did not observe correlation between RNFL thickness and axial length (p = 0.05). Corneal resistance factor was only positively correlated with the rim area (p = 0.001). The central corneal thickness did not correlate with the optic nerve parameters or with RNFL thickness. These associations were not found in the emmetropic group (p > 0.05 for all). Conclusions: The corneal biomechanics characterized with the Ocular Response Analyzer system are correlated with the optic disc profile and RNFL thickness in myopic children. Low CH values may indicate a reduction in the viscous dampening properties of the cornea and the sclera, especially in myopic children.

Role of dietary fibers in the nutritional management of hyperuricemia

Foods rich in adenine and hypoxanthine may contribute to the increase of uricemia. Hyperuricemia is associated with other pathological conditions pertaining to metabolic syndrome. Objective: the assessement of the impact of fiber rich diet on uricemia in patients with metabolic syndrome. Methods: the study involved 46 male patients with metabolic syndrome who claimed to have reduced mobility in fingers, hypertension, obesity, hyperglycemia and hyperuricemia. A validated questionnaire about dietary habits was applied at the beginning of the study and after 6 weeks of fiber-rich diet by eliminating from patients diet preparations of animal food and increased intake of vegetable foods. Blood presure, body mass index, blood glucose and uric acids were measured at the beginning of the study and after 6 weeks of fiber rich diet by daily consumption of 2 servings of added grains - 60g totally and vegetables 200g, fruits 300g respectively. Results: The study shows that at baseline all patients had an inadequate dietary intake of dietary fiber, 28.5 ± 2.2 g/day instead of 38 g per day.The increase in fiber intake of 10 ± 5 g/day was associated with a decrease of serum uric acid by 69.87% from 8.3  0.6 mg/dL to 5.8  0.5 mg/dL, p = 0.008, non-significant decrease of BMI (from 26.8  4.5 to 26.4  4.6 kg/m2, p<0.01), significant decrease of glycemia (from 130  0.8 to 105  4.2mg/dL, p <0.001) and significant decrease in blood pressure (from 150  10.6 to 130  8.4 mmHg, p <0.001). Conclusion: The fiber rich diet decreased blood uric acid, blood glucose levels an arterial pressure in patients with metabolic syndrome.

Effects of the fibers distribution in the human eardrum: A biomechanical study

The eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.

Effects of the fibers distribution in the human eardrum: A biomechanical study

The eardrum separates the external ear from the middle ear and it is responsible to convert the acoustical energy into mechanical energy. It is divided by pars tensa and pars flaccida. The aim of this work is to analyze the susceptibility of the four quadrants of the pars tensa under negative pressure, to different lamina propria fibers distribution. The development of associated ear pathology, in particular the formation of retraction pockets, is also evaluated. To analyze these effects, a computational biomechanical model of the tympano-ossicular chain was constructed using computerized tomography images and based on the finite element method. Three fibers distributions in the eardrum middle layer were compared: case 1 (eardrum with a circular band of fibers surrounding all quadrants equally), case 2 (eardrum with a circular band of fibers that decreases in thickness in posterior quadrants), case 3 (eardrum without circular fibers in the posterior/superior quadrant). A static analysis was performed by applying approximately 3000Pa in the eardrum. The pars tensa of the eardrum was divided in four quadrants and the displacement of a central point of each quadrant analyzed. The largest displacements of the eardrum were obtained for the eardrum without circular fibers in the posterior/superior quadrant.

A detector based on silica fibers for ion beam monitoring in a wide current range

A detector based on doped silica and optical fibers was developed to monitor the profile of particle accelerator beams of intensity ranging from 1 pA to tens of µA. Scintillation light produced in a fiber moving across the beam is measured, giving information on its position, shape and intensity. The detector was tested with a continuous proton beam at the 18 MeV Bern medical cyclotron used for radioisotope production and multi-disciplinary research. For currents from 1 pA to 20 µA, Ce3+ and Sb3+ doped silica fibers were used as sensors. Read out systems based on photodiodes, photomultipliers and solid state photomultipliers were employed. Profiles down to the pA range were measured with this method for the first time. For currents ranging from 1 pA to 3 µA, the integral of the profile was found to be linear with respect to the beam current, which can be measured by this detector with an accuracy of ∼1%. The profile was determined with a spatial resolution of 0.25 mm. For currents ranging from 5 µA to 20 µA, thermal effects affect light yield and transmission, causing distortions of the profile and limitations in monitoring capabilities. For currents higher than ∼1 µA, non doped optical fibers for both producing and transporting scintillation light were also successfully employed.

Final environmental assessment/environmental impact report for the American Telephone and Telegraph Company fiber optic cable right-of-way project, Cheyenne, Wyoming to Sacramento, California /

On cover: AT&T fiber optics cable project, Cheyenne, Wyoming to Sacramento, California ... December 1987."

Optobundle : a unique fiber optic multiplier /

Includes bibliographical references.

A theoretical analysis of the modulation characteristics of an electro-optic light value.

"C00-1469-0108"

Fused-quartz fibers : a survey of properties, applications, and production methods /

Bibliography: p. 18-26.

Vegetable fibers and their uses.

Includes bibliography.

High strength, high modulus fibers by pyrolysis of polymeric fibers

Mode of access: Internet.

Wool statistics, including mohair and other animal fibers.

Cover-title.

A possible application of organic fibers in high temperature environment /

This report was prepared by Fabric Research Laboratories, Inc. under USAF Contract No. AF33 (616)--6234 under Project No. 7320, Task No. 73201.