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Richard M. Hill - One of the best experts on this subject based on the ideXlab platform.
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Influence of lens design on the tear Pump Efficiency associated with plus-power rigid contact lenses: a comparison of single cut, lenticular, and minus-carrier designs.
Optometry and Vision Science, 1993Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:In order to determine the tear Pump efficiencies associated with three plus-power rigid contact lens designs (single cut, lenticular, and minus-carrier), we measured corneal oxygen uptake rates on the right eyes of six human subjects under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of the contact lens, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lens. The differences among the corneal oxygen uptake rates measured under static and dynamic conditions, relative to those measured for the normal open eye, served as an index of tear Pump Efficiency. Under both static and dynamic conditions, no significant differences were found among the corneal oxygen uptake rates associated with the three plus-power lens designs. In addition, no significant differences were found in the differences among the static and dynamic condition data, an indication of tear Pump Efficiency, associated with the three plus-power lens designs. This was true for both the population data and for the data from each subject. Nevertheless, there were significant differences among subjects in the static condition, dynamic condition, and difference data.
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Influence of power changes in single cut rigid contact lenses on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:Differences between corneal oxygen uptake rates measured after 5 min of static (without blinking) and 5 min of dynamic (with blinking once every 5 s) non-gas permeable (polymethyl methacrylate) contact lens wear, referenced to the oxygen uptake rates of the normal open eye, were used as indications of tear Pump efficiencies associated with each of seven contact lens back vertex powers (-9.00 to +9.00 D, in 3.00 D steps). Measurements were made in vivo on six human corneas showing with-the-rule (0.25 to 0.87 D) toricity. Lens overall diameter was 8.8 mm, optic zone diameter was 7.4 mm, and base curve radius was fitted "on K." Lens center thickness was 0.14 mm for all minus-powered lenses, and 0.19, 0.26, 0.34, and 0.41 mm for the plano, +3.00, +6.00, and +9.00 D lenses, respectively, maintaining an edge thickness of 0.11 mm. Under both static and dynamic wearing conditions, no significant differences were found among the corneal oxygen uptake rates associated with the various contact lens back vertex powers; however, the difference between the static and dynamic condition data, an indication of tear Pump Efficiency, was greatest for the -3.00 D lens. The difference values associated with the +9.00 and +6.00 D lenses were significantly lower than those associated with the minus power lenses.
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Influence of rigid contact lens base curve radius on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Richard M. Hill, Leo G. CarneyAbstract:The effects of rigid contact lens base curve radius changes on tear Pump Efficiency were determined by measuring oxygen uptake on six with-the-rule corneas (with toricities between 0.37 and 1.00 D) under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of polymethyl methacrylate (non-gas permeable) contact lenses, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lenses. The difference between the oxygen uptake rates measured under static and dynamic conditions provides an index of tear Pump Efficiency. Each subject wore a series of five lenses: fitted on K and 0.05 or 0.10 mm steeper and flatter than the flattest corneal meridian. The overall diameter of all lenses was 8.8 mm, the optic zone was 7.4 mm, the axial edge lift was 0.09 mm, and all other parameters were constant. The contact lens fitted on K was associated with the greatest central corneal oxygen debt under static conditions, whereas the same lens also provided for the best tear exchange with the blink. In addition, better tear exchange was found to be associated with larger palpebral aperture sizes.
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Rigid lens tear Pump Efficiency: effects of overall diameter/base curve combinations.
Optometry and Vision Science, 1991Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:The effect of changes in rigid contact lens overall and optic zone diameters on tear Pump Efficiency were studied using a polarographic technique. Six overall diameters ranged from 7.6 to 10.6 mm in 0.6-mm steps, with the optic zone diameter always being 1.4 mm smaller. Base curve radii were made flatter as lens overall/optic zone diameters increased in order to maintain a constant tear layer thickness. All other parameters were held constant. Oxygen uptake rates were measured for the normal, open eye, as well as after 5 min of static (without blinking) and dynamic (with blinking once every 5 s) wear of each lens design. Under both static and dynamic conditions, oxygen uptake rates increased with increase in lens overall/optic zone diameter. The differences between the static and dynamic condition data served as an index of tear Pump Efficiency for each lens. These differences decreased with increase in lens overall/optic zone diameter.
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Rigid contact lens design: effects of overall diameter changes on tear Pump Efficiency.
Optometry and Vision Science, 1991Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:The effects of rigid contact lens overall diameter changes on tear Pump Efficiency were studied for lenses of 7 overall diameters (8.2 to 10.0 mm in 0.3-mm steps) while maintaining all other parameters (including a 7.4-mm optic zone diameter) constant. Oxygen uptake rates were measured in the normal, open eye and after static (without blinking) and dynamic (with blinking once every 5 s) wear of oxygen-impermeable (polymethyl methacrylate) contact lenses. Differences between uptake rates obtained under static vs. dynamic conditions served as an index of tear Pump Efficiency for each lens. Tear Pump Efficiency increased with the use of progressively smaller lens diameters and subjects with large palpebral aperture sizes were also found to have better tear exchange (r = 0.934, p = 0.006 for the 9.1-mm overall diameter reference lens).
Barbara A. Fink - One of the best experts on this subject based on the ideXlab platform.
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Influence of lens design on the tear Pump Efficiency associated with plus-power rigid contact lenses: a comparison of single cut, lenticular, and minus-carrier designs.
Optometry and Vision Science, 1993Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:In order to determine the tear Pump efficiencies associated with three plus-power rigid contact lens designs (single cut, lenticular, and minus-carrier), we measured corneal oxygen uptake rates on the right eyes of six human subjects under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of the contact lens, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lens. The differences among the corneal oxygen uptake rates measured under static and dynamic conditions, relative to those measured for the normal open eye, served as an index of tear Pump Efficiency. Under both static and dynamic conditions, no significant differences were found among the corneal oxygen uptake rates associated with the three plus-power lens designs. In addition, no significant differences were found in the differences among the static and dynamic condition data, an indication of tear Pump Efficiency, associated with the three plus-power lens designs. This was true for both the population data and for the data from each subject. Nevertheless, there were significant differences among subjects in the static condition, dynamic condition, and difference data.
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Influence of power changes in single cut rigid contact lenses on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:Differences between corneal oxygen uptake rates measured after 5 min of static (without blinking) and 5 min of dynamic (with blinking once every 5 s) non-gas permeable (polymethyl methacrylate) contact lens wear, referenced to the oxygen uptake rates of the normal open eye, were used as indications of tear Pump efficiencies associated with each of seven contact lens back vertex powers (-9.00 to +9.00 D, in 3.00 D steps). Measurements were made in vivo on six human corneas showing with-the-rule (0.25 to 0.87 D) toricity. Lens overall diameter was 8.8 mm, optic zone diameter was 7.4 mm, and base curve radius was fitted "on K." Lens center thickness was 0.14 mm for all minus-powered lenses, and 0.19, 0.26, 0.34, and 0.41 mm for the plano, +3.00, +6.00, and +9.00 D lenses, respectively, maintaining an edge thickness of 0.11 mm. Under both static and dynamic wearing conditions, no significant differences were found among the corneal oxygen uptake rates associated with the various contact lens back vertex powers; however, the difference between the static and dynamic condition data, an indication of tear Pump Efficiency, was greatest for the -3.00 D lens. The difference values associated with the +9.00 and +6.00 D lenses were significantly lower than those associated with the minus power lenses.
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Influence of rigid contact lens base curve radius on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Richard M. Hill, Leo G. CarneyAbstract:The effects of rigid contact lens base curve radius changes on tear Pump Efficiency were determined by measuring oxygen uptake on six with-the-rule corneas (with toricities between 0.37 and 1.00 D) under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of polymethyl methacrylate (non-gas permeable) contact lenses, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lenses. The difference between the oxygen uptake rates measured under static and dynamic conditions provides an index of tear Pump Efficiency. Each subject wore a series of five lenses: fitted on K and 0.05 or 0.10 mm steeper and flatter than the flattest corneal meridian. The overall diameter of all lenses was 8.8 mm, the optic zone was 7.4 mm, the axial edge lift was 0.09 mm, and all other parameters were constant. The contact lens fitted on K was associated with the greatest central corneal oxygen debt under static conditions, whereas the same lens also provided for the best tear exchange with the blink. In addition, better tear exchange was found to be associated with larger palpebral aperture sizes.
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A comparision of the effects of rigid contact lens overall diameter and axial edge lift changes on tear Pump Efficiency
1991Co-Authors: Barbara A. Fink, Leo G. CarneyAbstract:Corneal oxygen uptake was used to compare the effects of changes in lens overall and optic-zone diameter to changes in lens axial edge lift on tear Pump Efficiency. Measurements were made on the right cornea of six human subjects under three conditions; (1) normal open eye, (2) after 5 minutes of static (without blinking) wear of a poly(methyl methacrylate) (non-gas permeable) contact lens, and (3) after 5 minutes of dynamic (with blinking once every 5 seconds) wear of the same lens. The differences between the oxygen uptake rates measured under static and dynamic conditions for a given lens design provided an index of the tear Pump Efficiency for that design. Two sets of five lenses were worn by each subject. In the first set, lens overall diameter varied from 8.2 to 9.4 mm in 0.3 mm steps, with the optic-zone diameter being 1.4 mm smaller. All other parameters were constant, including a 0.09 mm axial edge lift. In the second set of lenses, axial edge lift varied from 0.05 to 0.13 mm in 0.02mm steps; overall diameter was 8.8 mm, optic, zone diameter was 7.4 mm, and all other parameters were the same as those in Set 1. Tear Pump Efficiency was greatest for small lenses and for lenses with large axial edge lifts. A 0.3 mm decrease in overall diameter was approximately equivalent to a 0.03 mm increase in axial edge lift as a means of enhancing tear Pump Efficiency.
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Rigid lens tear Pump Efficiency: effects of overall diameter/base curve combinations.
Optometry and Vision Science, 1991Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:The effect of changes in rigid contact lens overall and optic zone diameters on tear Pump Efficiency were studied using a polarographic technique. Six overall diameters ranged from 7.6 to 10.6 mm in 0.6-mm steps, with the optic zone diameter always being 1.4 mm smaller. Base curve radii were made flatter as lens overall/optic zone diameters increased in order to maintain a constant tear layer thickness. All other parameters were held constant. Oxygen uptake rates were measured for the normal, open eye, as well as after 5 min of static (without blinking) and dynamic (with blinking once every 5 s) wear of each lens design. Under both static and dynamic conditions, oxygen uptake rates increased with increase in lens overall/optic zone diameter. The differences between the static and dynamic condition data served as an index of tear Pump Efficiency for each lens. These differences decreased with increase in lens overall/optic zone diameter.
Blaine Hanson - One of the best experts on this subject based on the ideXlab platform.
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Water Encyclopedia - Deep‐Well Turbine Pumps
Water Encyclopedia, 2005Co-Authors: Blaine HansonAbstract:Deep-well turbine Pumps are used to Pump groundwater. They consist of a housing or bowl, impellers, and a shaft, all of which are installed in the well. Impeller types include closed and semi-open impellers. Submersible Pumps are a modification of deep-well turbines for which the electric motor is installed in the well, instead of at the ground surface. Performance curves, developed by Pump manufacturers, describe relationships between total head and capacity, Pump Efficiency and capacity, and horsepower demand and capacity. These curves can select new Pumps and evaluate existing Pumps. A common cause of declining Pump Efficiency with time is wear caused by sand in the Pumped water. Keywords: deep-well turbine; Pumps; Pump evaluation; performance curves
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Water Encyclopedia - Deep-Well Turbine Pumps
Water Encyclopedia, 2005Co-Authors: Blaine HansonAbstract:Deep-well turbine Pumps are used to Pump groundwater. They consist of a housing or bowl, impellers, and a shaft, all of which are installed in the well. Impeller types include closed and semi-open impellers. Submersible Pumps are a modification of deep-well turbines for which the electric motor is installed in the well, instead of at the ground surface. Performance curves, developed by Pump manufacturers, describe relationships between total head and capacity, Pump Efficiency and capacity, and horsepower demand and capacity. These curves can select new Pumps and evaluate existing Pumps. A common cause of declining Pump Efficiency with time is wear caused by sand in the Pumped water. Keywords: deep-well turbine; Pumps; Pump evaluation; performance curves
Aaron Praktiknjo - One of the best experts on this subject based on the ideXlab platform.
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Time series of heat demand and heat Pump Efficiency for energy system modeling
Scientific Data, 2019Co-Authors: Oliver Ruhnau, Lion Hirth, Aaron PraktiknjoAbstract:With electric heat Pumps substituting for fossil-fueled alternatives, the temporal variability of their power consumption becomes increasingly important to the electricity system. To easily include this variability in energy system analyses, this paper introduces the “When2Heat” dataset comprising synthetic national time series of both the heat demand and the coefficient of performance (COP) of heat Pumps. It covers 16 European countries, includes the years 2008 to 2018, and features an hourly resolution. Demand profiles for space and water heating are computed by combining gas standard load profiles with spatial temperature and wind speed reanalysis data as well as population geodata. COP time series for different heat sources – air, ground, and groundwater – and different heat sinks – floor heating, radiators, and water heating – are calculated based on COP and heating curves using reanalysis temperature data. The dataset, as well as the scripts and input parameters, are publicly available under an open source license on the Open Power System Data platform. Measurement(s) time sampled measurement data set • heating Technology Type(s) computational modeling technique • digital curation Factor Type(s) year Sample Characteristic - Environment anthropogenic environment Sample Characteristic - Location Austria • Belgium • Bulgaria • Czech Republic • Germany • French Republic • Great Britain • Croatia • Hungary • Republic of Ireland • Kingdom of the Netherlands • Poland • Romania • Slovenia • Slovak Republic Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.9878849
Leo G. Carney - One of the best experts on this subject based on the ideXlab platform.
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Influence of lens design on the tear Pump Efficiency associated with plus-power rigid contact lenses: a comparison of single cut, lenticular, and minus-carrier designs.
Optometry and Vision Science, 1993Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:In order to determine the tear Pump efficiencies associated with three plus-power rigid contact lens designs (single cut, lenticular, and minus-carrier), we measured corneal oxygen uptake rates on the right eyes of six human subjects under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of the contact lens, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lens. The differences among the corneal oxygen uptake rates measured under static and dynamic conditions, relative to those measured for the normal open eye, served as an index of tear Pump Efficiency. Under both static and dynamic conditions, no significant differences were found among the corneal oxygen uptake rates associated with the three plus-power lens designs. In addition, no significant differences were found in the differences among the static and dynamic condition data, an indication of tear Pump Efficiency, associated with the three plus-power lens designs. This was true for both the population data and for the data from each subject. Nevertheless, there were significant differences among subjects in the static condition, dynamic condition, and difference data.
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Influence of power changes in single cut rigid contact lenses on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:Differences between corneal oxygen uptake rates measured after 5 min of static (without blinking) and 5 min of dynamic (with blinking once every 5 s) non-gas permeable (polymethyl methacrylate) contact lens wear, referenced to the oxygen uptake rates of the normal open eye, were used as indications of tear Pump efficiencies associated with each of seven contact lens back vertex powers (-9.00 to +9.00 D, in 3.00 D steps). Measurements were made in vivo on six human corneas showing with-the-rule (0.25 to 0.87 D) toricity. Lens overall diameter was 8.8 mm, optic zone diameter was 7.4 mm, and base curve radius was fitted "on K." Lens center thickness was 0.14 mm for all minus-powered lenses, and 0.19, 0.26, 0.34, and 0.41 mm for the plano, +3.00, +6.00, and +9.00 D lenses, respectively, maintaining an edge thickness of 0.11 mm. Under both static and dynamic wearing conditions, no significant differences were found among the corneal oxygen uptake rates associated with the various contact lens back vertex powers; however, the difference between the static and dynamic condition data, an indication of tear Pump Efficiency, was greatest for the -3.00 D lens. The difference values associated with the +9.00 and +6.00 D lenses were significantly lower than those associated with the minus power lenses.
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Influence of rigid contact lens base curve radius on tear Pump Efficiency.
Optometry and Vision Science, 1992Co-Authors: Barbara A. Fink, Richard M. Hill, Leo G. CarneyAbstract:The effects of rigid contact lens base curve radius changes on tear Pump Efficiency were determined by measuring oxygen uptake on six with-the-rule corneas (with toricities between 0.37 and 1.00 D) under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of polymethyl methacrylate (non-gas permeable) contact lenses, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lenses. The difference between the oxygen uptake rates measured under static and dynamic conditions provides an index of tear Pump Efficiency. Each subject wore a series of five lenses: fitted on K and 0.05 or 0.10 mm steeper and flatter than the flattest corneal meridian. The overall diameter of all lenses was 8.8 mm, the optic zone was 7.4 mm, the axial edge lift was 0.09 mm, and all other parameters were constant. The contact lens fitted on K was associated with the greatest central corneal oxygen debt under static conditions, whereas the same lens also provided for the best tear exchange with the blink. In addition, better tear exchange was found to be associated with larger palpebral aperture sizes.
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A comparision of the effects of rigid contact lens overall diameter and axial edge lift changes on tear Pump Efficiency
1991Co-Authors: Barbara A. Fink, Leo G. CarneyAbstract:Corneal oxygen uptake was used to compare the effects of changes in lens overall and optic-zone diameter to changes in lens axial edge lift on tear Pump Efficiency. Measurements were made on the right cornea of six human subjects under three conditions; (1) normal open eye, (2) after 5 minutes of static (without blinking) wear of a poly(methyl methacrylate) (non-gas permeable) contact lens, and (3) after 5 minutes of dynamic (with blinking once every 5 seconds) wear of the same lens. The differences between the oxygen uptake rates measured under static and dynamic conditions for a given lens design provided an index of the tear Pump Efficiency for that design. Two sets of five lenses were worn by each subject. In the first set, lens overall diameter varied from 8.2 to 9.4 mm in 0.3 mm steps, with the optic-zone diameter being 1.4 mm smaller. All other parameters were constant, including a 0.09 mm axial edge lift. In the second set of lenses, axial edge lift varied from 0.05 to 0.13 mm in 0.02mm steps; overall diameter was 8.8 mm, optic, zone diameter was 7.4 mm, and all other parameters were the same as those in Set 1. Tear Pump Efficiency was greatest for small lenses and for lenses with large axial edge lifts. A 0.3 mm decrease in overall diameter was approximately equivalent to a 0.03 mm increase in axial edge lift as a means of enhancing tear Pump Efficiency.
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Rigid lens tear Pump Efficiency: effects of overall diameter/base curve combinations.
Optometry and Vision Science, 1991Co-Authors: Barbara A. Fink, Leo G. Carney, Richard M. HillAbstract:The effect of changes in rigid contact lens overall and optic zone diameters on tear Pump Efficiency were studied using a polarographic technique. Six overall diameters ranged from 7.6 to 10.6 mm in 0.6-mm steps, with the optic zone diameter always being 1.4 mm smaller. Base curve radii were made flatter as lens overall/optic zone diameters increased in order to maintain a constant tear layer thickness. All other parameters were held constant. Oxygen uptake rates were measured for the normal, open eye, as well as after 5 min of static (without blinking) and dynamic (with blinking once every 5 s) wear of each lens design. Under both static and dynamic conditions, oxygen uptake rates increased with increase in lens overall/optic zone diameter. The differences between the static and dynamic condition data served as an index of tear Pump Efficiency for each lens. These differences decreased with increase in lens overall/optic zone diameter.
