AIM:To compare the vergence mechanisms between good and poor sleepers in university students.METHODS:A total of 64 university students were recruited in this study.The validated Malay version of Pittsburgh Sleep Quali...AIM:To compare the vergence mechanisms between good and poor sleepers in university students.METHODS:A total of 64 university students were recruited in this study.The validated Malay version of Pittsburgh Sleep Quality Index questionnaire(PSQI-M)was used to measure the participants’sleep quality over the past month.Participants were categorized as good sleepers(n=32)and poor sleepers(n=32)based on the PSQI-M scores.Heterophoria and fusional vergences were measured at distance and near.Mann-Whitney U test was used to compare heterophoria,negative fusional vergence(NFV),and positive fusional vergence(PFV)at distance and near between good and poor sleepers.Spearman correlation analysis was used to study the relationship between PSQI-M score and PFV at distance.RESULTS:Both distance and near heterophorias were not significantly different between good and poor sleepers(P>0.05).There was a difference in distance PFV(P<0.05)between good and poor sleepers,but not in distance NFV,near NFV,and near PFV(P>0.05).Distance PFV was negatively correlated with PSQI-M score(rs=-0.33,P<0.05).CONCLUSION:University students with poor sleep quality demonstrates a reduced ability to maintain fusion with increasing convergence demand at distance.Sleep quality assessment during binocular vision examination in university students is recommended.展开更多
A control model of binocular vergence eye movements is presented. The control model can reduce blind areas caused by the double cameras in motion platform. In order to validate the model performance, an experimental p...A control model of binocular vergence eye movements is presented. The control model can reduce blind areas caused by the double cameras in motion platform. In order to validate the model performance, an experimental platform and its control system based on TMS320LF2407 are designed. The control system has its compacted configuration and high reliability. The simulation and experimental results show that the control system can realize binocular vergence movements. Compared with the conventional moving double cameras system, this new system can considerably reduce blind areas.展开更多
Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination.While studies have mapped and investigated the neural substrates of vergence,it is not well understood whet...Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination.While studies have mapped and investigated the neural substrates of vergence,it is not well understood whether vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits.The test-retest reliability of stimulus-induced vergence eye movement tasks during a functional magnetic resonance imaging(fMRI)experiment is important for future randomized clinical trials(RCTs).In this study,we established region of interest(ROI)masks for the vergence neural circuit.Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3 T Siemens scanner.The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four vergence eye movements.The test-retest reliability of task-activation was assessed using the intraclass correlation coefficient(ICC),and that of spatial extent was assessed using the Dice coefficient.Functional activation during the vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex(ICC=0.8),parietal eye fields(ICC=0.6),supplementary eye field(ICC=0.5),frontal eye fields(ICC=0.5),and oculomotor vermis(ICC=0.6).The results demonstrate significant test-retest reliability in the ROIs of the vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight vergence eye movements compared to sustained fixation.These ROIs can be used in future longitudinal RCTs to study patient populations with vergence dysfunctions.展开更多
In this paper, we establish the semi-local convergence theorem of the Breat method with regional estimation. By an in-depth investigation in to the algorithm structure of the method, we convert the Brent method iato a...In this paper, we establish the semi-local convergence theorem of the Breat method with regional estimation. By an in-depth investigation in to the algorithm structure of the method, we convert the Brent method iato an approximate Newton method with a special error term. Bsaed on such equivaleat variation, under a similar condition of the Newton-Kantorovich theorem of the Newton method, we establish a semi-local convergence theorem of the Breat method. This theorem provides a sufficient theoretical basis for initial choices of the Breat method.展开更多
The objective of this paper is to present a Bayesian approach based on Kullback- Leibler divergence for assessing local influence in a growth curve model with general co- variance structure. Under certain prior distri...The objective of this paper is to present a Bayesian approach based on Kullback- Leibler divergence for assessing local influence in a growth curve model with general co- variance structure. Under certain prior distribution assumption, the Kullback-Leibler di- vergence is used to measure the influence of some minor perturbation on the posterior distribution of unknown parameter. This leads to the diagnostic statistic for detecting which response is locally influential. As an application, the common covariance-weighted perturbation scheme is thoroughly considered.展开更多
AIM: To compare visual efficiency, specifically accommodation, vergence, and oculomotor functions among athletes and non-athletes. METHODS: A cross-sectional study on sports vision screening was used to evaluate the v...AIM: To compare visual efficiency, specifically accommodation, vergence, and oculomotor functions among athletes and non-athletes. METHODS: A cross-sectional study on sports vision screening was used to evaluate the visual skills of 214 elementary students(107 athletes, 107 non-athletes), aged between 13 and 16y. The visual screening assessed visual parameters such as ocular motor alignment, accommodation, and vergence functions. RESULTS: Mean visual parameters were compared between age-group matched athletes(mean age 14.82±0.98y) and non-athletes(mean age 15.00±1.04y). The refractive errors of all participants were corrected to maximal attainable best corrected visual acuity of log MAR 0.0. Accommodation function assessment evaluated amplitude of accommodation and accommodation facility. Vergence functions measured the near point of convergence, vergence facility, and distance fusional vergence at break and recovery point. Ocular motor alignment was not statistically significant between both groups. Athletes had a statistically significant amplitude of accommodation for both the right eye(t=2.30, P=0.02) and the left eye(t=1.99, P=0.05). Conversely, non-athletes had better accommodation facility(t=-2.54, P=0.01) and nearpoint of convergence(t=4.39, P<0.001) when compared to athletes. Vergence facility was found to be better among athletes(t=2.47, P=0.01). Nevertheless, non-athletes were significantly better for both distance negative and positive fusional vergence.CONCLUSION: Although the findings are still inconclusive as to whether athletes had superior visual skills as compared to non-athletes, it remains important to identify and elucidate the key visual skills needed by athletes in order for them to achieve higher performance in their sports.展开更多
Background Virtual Reality(VR)technologies have advanced fast and have been applied to a wide spectrum of sectors in the past few years.VR can provide an immersive experience to users by generating virtual images and ...Background Virtual Reality(VR)technologies have advanced fast and have been applied to a wide spectrum of sectors in the past few years.VR can provide an immersive experience to users by generating virtual images and displaying the virtual images to the user with a head-mounted display(HMD)which is a primary component of VR.Normally,an HMD contains a list of hardware components,e.g.,housing pack,micro LCD display,microcontroller,optical lens,etc.Settings of VR HMD to accommodate the user's inter-pupil distance(IPD)and the user's eye focus power are important for the user's experience with VR.Methods Although various methods have been developed towards IPD and focus adjustments for VR HMD,the increased cost and complexity impede the possibility for users who wish to assemble their own VR HMD for various purposes,e.g.,DIY teaching,etc.In our paper,we present a novel design towards building a customizable and adjustable HMD for VR in a cost-effective manner.Modular design methodology is adopted,and the VR HMD can be easily printed with 3D printers.The design also features adjustable IPD and variable distance between the optical lens and the display.It can help to mitigate the vergence and accommodation conflict issue.Results A prototype of the customizable and adjustable VR HMD has been successfully built up with off-the-shelf components.A VR software program running on Raspberry Pi board has been developed and can be utilized to show the VR effects.A user study with 20 participants is conducted with positive feedback on our novel design.Conclusions Modular design can be successfully applied for building up VR HMD with 3D printing.It helps to promote the wide application of VR at affordable costs while featuring flexibility and adjustability.展开更多
This article deals with the numerical solution to the magneto-thermoelasticity model,which is a system of the third order partial differential equations.By introducing a new function,the model is transformed into a sy...This article deals with the numerical solution to the magneto-thermoelasticity model,which is a system of the third order partial differential equations.By introducing a new function,the model is transformed into a system of the second order generalized hyperbolic equations.A priori estimate with the conservation for the problem is established.Then a three-level finite difference scheme is derived.The unique solvability,unconditional stability and second-order convergence in L∞-norm of the difference scheme are proved.One numerical example is presented to demonstrate the accuracy and efficiency of the proposed method.展开更多
Based on the equivalent integro-differential form of the considered problem, a numerical approach to solving the two-dimensional nonlinear time fractional wave equations(NTFWEs) is considered in this paper. To this e...Based on the equivalent integro-differential form of the considered problem, a numerical approach to solving the two-dimensional nonlinear time fractional wave equations(NTFWEs) is considered in this paper. To this end, an alternating direction implicit(ADI) numerical scheme is derived. The scheme is established by combining the secondorder convolution quadrature formula and Crank–Nicolson technique in time and afourth-order difference approach in space. The convergence and unconditional stability of the proposed compact ADI scheme are strictly discussed after a concise solvabilityanalysis. A numerical example is shown to demonstrate the theoretical analysis.展开更多
文摘AIM:To compare the vergence mechanisms between good and poor sleepers in university students.METHODS:A total of 64 university students were recruited in this study.The validated Malay version of Pittsburgh Sleep Quality Index questionnaire(PSQI-M)was used to measure the participants’sleep quality over the past month.Participants were categorized as good sleepers(n=32)and poor sleepers(n=32)based on the PSQI-M scores.Heterophoria and fusional vergences were measured at distance and near.Mann-Whitney U test was used to compare heterophoria,negative fusional vergence(NFV),and positive fusional vergence(PFV)at distance and near between good and poor sleepers.Spearman correlation analysis was used to study the relationship between PSQI-M score and PFV at distance.RESULTS:Both distance and near heterophorias were not significantly different between good and poor sleepers(P>0.05).There was a difference in distance PFV(P<0.05)between good and poor sleepers,but not in distance NFV,near NFV,and near PFV(P>0.05).Distance PFV was negatively correlated with PSQI-M score(rs=-0.33,P<0.05).CONCLUSION:University students with poor sleep quality demonstrates a reduced ability to maintain fusion with increasing convergence demand at distance.Sleep quality assessment during binocular vision examination in university students is recommended.
基金supported by the National Natural Science Foundation of China (Grant Nos.60605028, 50975168)National Hi-tech Research and Development Program of China (Grant Nos.2007AA04Z225, 2009AA04Z211)+1 种基金Program for Excellent Young Teachers of Shanghai (Grant Nos.07Q14024,07QH14006)Shuguang Program of Shanghai (Grant No.07SG47)
文摘A control model of binocular vergence eye movements is presented. The control model can reduce blind areas caused by the double cameras in motion platform. In order to validate the model performance, an experimental platform and its control system based on TMS320LF2407 are designed. The control system has its compacted configuration and high reliability. The simulation and experimental results show that the control system can realize binocular vergence movements. Compared with the conventional moving double cameras system, this new system can considerably reduce blind areas.
基金supported by the National Eye Institute of the National Institutes of Health,Department of Health and Human Services,Bethesda,MD,USA(NEI ROIEY023261 to TLA)。
文摘Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination.While studies have mapped and investigated the neural substrates of vergence,it is not well understood whether vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits.The test-retest reliability of stimulus-induced vergence eye movement tasks during a functional magnetic resonance imaging(fMRI)experiment is important for future randomized clinical trials(RCTs).In this study,we established region of interest(ROI)masks for the vergence neural circuit.Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3 T Siemens scanner.The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four vergence eye movements.The test-retest reliability of task-activation was assessed using the intraclass correlation coefficient(ICC),and that of spatial extent was assessed using the Dice coefficient.Functional activation during the vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex(ICC=0.8),parietal eye fields(ICC=0.6),supplementary eye field(ICC=0.5),frontal eye fields(ICC=0.5),and oculomotor vermis(ICC=0.6).The results demonstrate significant test-retest reliability in the ROIs of the vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight vergence eye movements compared to sustained fixation.These ROIs can be used in future longitudinal RCTs to study patient populations with vergence dysfunctions.
文摘In this paper, we establish the semi-local convergence theorem of the Breat method with regional estimation. By an in-depth investigation in to the algorithm structure of the method, we convert the Brent method iato an approximate Newton method with a special error term. Bsaed on such equivaleat variation, under a similar condition of the Newton-Kantorovich theorem of the Newton method, we establish a semi-local convergence theorem of the Breat method. This theorem provides a sufficient theoretical basis for initial choices of the Breat method.
基金Supported by the fund of the Yunnan Education Committee!(NO.9941072)
文摘The objective of this paper is to present a Bayesian approach based on Kullback- Leibler divergence for assessing local influence in a growth curve model with general co- variance structure. Under certain prior distribution assumption, the Kullback-Leibler di- vergence is used to measure the influence of some minor perturbation on the posterior distribution of unknown parameter. This leads to the diagnostic statistic for detecting which response is locally influential. As an application, the common covariance-weighted perturbation scheme is thoroughly considered.
基金Supported by the Ministry of Higher Education Malaysia Sports Grant[No.KPT.N.660-7 Jld 7(3)]UKM Research Code NN-2013-069
文摘AIM: To compare visual efficiency, specifically accommodation, vergence, and oculomotor functions among athletes and non-athletes. METHODS: A cross-sectional study on sports vision screening was used to evaluate the visual skills of 214 elementary students(107 athletes, 107 non-athletes), aged between 13 and 16y. The visual screening assessed visual parameters such as ocular motor alignment, accommodation, and vergence functions. RESULTS: Mean visual parameters were compared between age-group matched athletes(mean age 14.82±0.98y) and non-athletes(mean age 15.00±1.04y). The refractive errors of all participants were corrected to maximal attainable best corrected visual acuity of log MAR 0.0. Accommodation function assessment evaluated amplitude of accommodation and accommodation facility. Vergence functions measured the near point of convergence, vergence facility, and distance fusional vergence at break and recovery point. Ocular motor alignment was not statistically significant between both groups. Athletes had a statistically significant amplitude of accommodation for both the right eye(t=2.30, P=0.02) and the left eye(t=1.99, P=0.05). Conversely, non-athletes had better accommodation facility(t=-2.54, P=0.01) and nearpoint of convergence(t=4.39, P<0.001) when compared to athletes. Vergence facility was found to be better among athletes(t=2.47, P=0.01). Nevertheless, non-athletes were significantly better for both distance negative and positive fusional vergence.CONCLUSION: Although the findings are still inconclusive as to whether athletes had superior visual skills as compared to non-athletes, it remains important to identify and elucidate the key visual skills needed by athletes in order for them to achieve higher performance in their sports.
基金Supported by the Computing Science Program jointly offered by Singapore Institute of Technology and University of Glasgow.
文摘Background Virtual Reality(VR)technologies have advanced fast and have been applied to a wide spectrum of sectors in the past few years.VR can provide an immersive experience to users by generating virtual images and displaying the virtual images to the user with a head-mounted display(HMD)which is a primary component of VR.Normally,an HMD contains a list of hardware components,e.g.,housing pack,micro LCD display,microcontroller,optical lens,etc.Settings of VR HMD to accommodate the user's inter-pupil distance(IPD)and the user's eye focus power are important for the user's experience with VR.Methods Although various methods have been developed towards IPD and focus adjustments for VR HMD,the increased cost and complexity impede the possibility for users who wish to assemble their own VR HMD for various purposes,e.g.,DIY teaching,etc.In our paper,we present a novel design towards building a customizable and adjustable HMD for VR in a cost-effective manner.Modular design methodology is adopted,and the VR HMD can be easily printed with 3D printers.The design also features adjustable IPD and variable distance between the optical lens and the display.It can help to mitigate the vergence and accommodation conflict issue.Results A prototype of the customizable and adjustable VR HMD has been successfully built up with off-the-shelf components.A VR software program running on Raspberry Pi board has been developed and can be utilized to show the VR effects.A user study with 20 participants is conducted with positive feedback on our novel design.Conclusions Modular design can be successfully applied for building up VR HMD with 3D printing.It helps to promote the wide application of VR at affordable costs while featuring flexibility and adjustability.
基金National Natural Science Foundation of China(No.11271068)the Research and Innovation Project for College Graduates of Jiangsu Province(No.CXLX110093).
文摘This article deals with the numerical solution to the magneto-thermoelasticity model,which is a system of the third order partial differential equations.By introducing a new function,the model is transformed into a system of the second order generalized hyperbolic equations.A priori estimate with the conservation for the problem is established.Then a three-level finite difference scheme is derived.The unique solvability,unconditional stability and second-order convergence in L∞-norm of the difference scheme are proved.One numerical example is presented to demonstrate the accuracy and efficiency of the proposed method.
基金This survey is supported by the National Natural Science Foundation of China(Grant No.11371029)the Quality Engineering Project of Colleges and Universities in Anhui Province(Grant No.2018kfk136).
文摘Based on the equivalent integro-differential form of the considered problem, a numerical approach to solving the two-dimensional nonlinear time fractional wave equations(NTFWEs) is considered in this paper. To this end, an alternating direction implicit(ADI) numerical scheme is derived. The scheme is established by combining the secondorder convolution quadrature formula and Crank–Nicolson technique in time and afourth-order difference approach in space. The convergence and unconditional stability of the proposed compact ADI scheme are strictly discussed after a concise solvabilityanalysis. A numerical example is shown to demonstrate the theoretical analysis.
