Myopia induced by flickering light in guinea pigs: a detailed assessment on susceptibility of different frequencies

AIM: To investigate the effectiveness and feasibility of inducing myopia in guinea pigs by flickering light (FL) stimulation with different frequencies. METHODS: Seventy 2 -week-old guinea pigs were randomly assigned to six groups: five FL groups and a control group (n =12 for each). Animals in the five FL groups were raised under 500lx illumination with a duty diurnal cycle of 50% at a flash rate of 5, 1, 0.5, 0.25 and 0.1Hz respectively. Those in the control group were reared under steady 250lx illumination. Refraction, axial length, and radius of curvature were measured before and at 2, 4, 6, 8, 10 and 12 weeks after treatment. At week 12, the eyeballs were taken out and three ocular dimensions and dry weight of sclera were measured. RESULTS: A myopic shift and axial eye length increase developed in the five FL groups. Stimulation at 0.5Hz caused greater changes in myopic shift, axial elongation, eyeball dimension, and dry weight of sclera than stimulation at other frequencies. Compared with controls, eyes in 0.5Hz group were approximately -5.5 ±1.5D more myopic with increase in horizontal, vertical, axial dimensions by 0.89 ±0.3mm, 0.69 ±0.2mm, 1.12 ±0.2mm respectively and with increase in dry weight of sclera by 0.44mg. CONCLUSION: Chronic exposure to periodic illumination at temporal frequency is attended by development of excessive ocular enlargement and myopic refractive error. Emmetropization could bedisrupted differently by frequency alteration.

光照对ADS模式TFT-LCD Flicker漂移的影响

在挠曲电效应的基础上,研究了光照对ADS模式TFT-LCD Flicker漂移的影响。首先研究了正常点灯下Flicker漂移情况,然后测试了不加背光和降低背光亮度下的Flicker漂移,最后研究了光照panel一段时间后Flicker漂移情况。实验结果表明,光照使Cell盒内产生了离子,驱动信号电压存在时液晶发生极化,产生的"力"吸附离子,从而形成了直流偏压,产生了Flicker漂移。降低光照强度Flicker漂移程度减弱。利用该结果在一定程度上对显示器整体设计和品质的改善有重要指导意义。

Critical flicker frequency for diagnosis and assessment of recovery from minimal hepatic encephalopathy in patients with cirrhosis

BACKGROUND:Minimal hepatic encephalopathy (MHE) impairs quality of life and predicts overt hepatic encephalopathy (HE) in cirrhotic patients.Diagnosis of MHE requires cumbersome tests.Lactulose is effective in the treatment of MHE.This study aimed to evaluate the use of critical flicker frequency (CFF) for the diagnosis of MHE in cirrhotic patients after treatment.METHODS:One hundred and ten patients were evaluated by psychometry (number connection tests A,B or figure connection tests A,B),P300 auditory event related potential (P300ERP),venous ammonia,and CFF for MHE.MHE was diagnosed by abnormal psychometry (>2SD age matched controls) and P300ERP.MHE patients were treated with lactulose for one month.Response was defined by normalization (<2SD of matched controls) of both psychometry and P300ERP.RESULTS:Of the 110 patients [Child Turcott Pugh score A:B:C 39:42:29,(age 41.6±11.6 years,M:F 82:28)],75 (68%) had abnormal results of psychometric tests,and 74 (67%) had prolonged P300ERP.Fifteen (20%) patients with abnormal results of psychometric tests had normal P300ERP.Thus sixty (54.5%) patients were diagnosed as having MHE.After treatment for one month,34 (57%) recovered while 26 (43%) continued to have abnormal resents of psychometric or P300ERP tests.CFF was <39 Hz in 72 (65.4%) patients before treatment and in 20 (33.3%) after treatment.CFF sensitivity,specificity,positive predictive value,negative predictive value,and diagnostic accuracy for the assessment of recovery of MHE were 65%,91%,85%,77% and 80%,respectively.CONCLUSION:CFF is a simple,relatively reliable,and accurate test without any dependence on age or literacy in the diagnosis and assessment of recovery of patients with MHE.

TFT-LCD屏的Flicker和DC残留的研究及改善

由于平面电场的非对称设计和挠曲电效应的存在,导致正负帧作用下透过率不同,目视有很明显的闪烁。本文在396 mm(15.6 in)FHD(1 920×1 080)竖双畴结构的基础上,通过LCD expert软件模拟平面电场显示模式正负帧作用下电压-穿透率(Voltage-Transmittance,V-T)曲线,同时,实测了像素电极(pixel-ITO)不同线宽线距产品的残留DC(Direct Current)值/Flrcker数值等,得出较好的实验条件,对今后的像素设计有一定的指导意义。

A User-Friendly SSVEP-Based BCI Using Imperceptible Phase-Coded Flickers at 60Hz

A brain-computer interface(BCI)system based on steady-state visual evoked potentials(SSVEP)was developed by four-class phase-coded stimuli.SSVEPs elicited by flickers at 60Hz,which is higher than the critical fusion frequency(CFF),were compared with those at 15Hz and 30Hz.SSVEP components in electroencephalogram(EEG)were detected using task related component analysis(TRCA)method.Offline analysis with 17 subjects indicated that the highest information transfer rate(ITR)was 29.80±4.65bpm with 0.5s data length for 60Hz and the classification accuracy was 70.07±4.15%.The online BCI system reached an averaged classification accuracy of 87.75±3.50%at 60Hz with 4s,resulting in an ITR of 16.73±1.63bpm.In particular,the maximum ITR for a subject was 80bpm with 0.5s at 60Hz.Although the BCI performance of 60Hz was lower than that of 15Hz and 30Hz,the results of the behavioral test indicated that,with no perception of flicker,the BCI system with 60Hz was more comfortable to use than 15Hz and 30Hz.Correlation analysis revealed that SSVEP with higher signal-to-noise ratio(SNR)corresponded to better classification performance and the improvement in comfortableness was accompanied by a decrease in performance.This study demonstrates the feasibility and potential of a user-friendly SSVEP-based BCI using imperceptible flickers.

LED Flicker: A Drawback or an Opportunity?

In this paper we examine the flicker of commercial LED lamps and with the help of volunteers we explore the parameter space (frequency and duty cycle) in order to find pulsing operating conditions under which the light fluctuations are not visually perceived. The results show that LEDs under mains voltage manifest the most extreme cases of flicker and we also confirm that under pulsing mode the overall impression is of higher brightness which is an opportunity for energy savings. The results also show that the background color and luminance contrast is of high importance. Finally we propose an easy method for consumers to detect flickering of light sources under mains voltage.

FLICKER INDEX METHOD FOR EVALUATING FLICKER IN COLOR PDPs

Objective In order to red uc e the flicker in color plasma display panel (PDP), the highly peaked light outpu t at certain positions and the strong luminance difference among subfields, whic h cause flicker in PDP, is analyzed; and a flicker index method is developed to evaluate flicker in PDP based on the flicker theory and the electroencephalograp h response model for luminance. Methods This method considers f licker as a main result of the fundamental frequency component of luminance supe rimposed on the DC-component, the flicker index is defined as ratio between the positive square roots of the sum of the two square components. Results & Conclusion The calculation results of flicker index indicate that flicker can be obviously weakened via increase of subfield number, symmetrical s election and homogeneous interlaced distribution of major weight subfields . Fli cker can be further reduced by choosing the suitable subfield order according to gray scale region of image.

Flicker defined form and RareBit measurements lack in specificity of visual pathways

AIM:To evaluate the different visual pathways represented by the Heidelberg Engineering Perimeter flicker defined form and RareBit(magnocellular and parvocellular respectively)in different age-groups and according to the fatigue.METHODS:Totally 64 eyes of 32 healthy subjects were included in the prospective study.Each participant underwent screening—ophthalmic examination including best-corrected visual acuity,anterior and posterior segment assessment,and visual field examination with Heidelberg Edge Perimetry(HEP)-standard automated perimeter(SAP)24-2.They were observed for 2 y previously to the enrollment.This helped to define that the enrolled patients did not bear the glaucoma-developing potential.During the screening and after two years the HEP had been conducted in the standard protocol 24-2 and RareBit perimetry(RBP)in accordance with the manufacturer’s description.Participants were randomly assigned to the groups:flicker defined form(FDF)-first or RBP-first.This defined from which additional visual field test the participant started.Participants were additionally subdivided to younger and older study groups.The effect of subject variables was explored with Mann-Whitney U-test.Testing for the presence of correlations between parameters was performed using the Spearman Rank Order Correlations and confirmed by the parametric tests.For the influence of additional factors,the Kruskal-Wallis test was performed.RESULTS:The positive correlation between meandeviation(MD)and mean hit rate(MHR)and pattern standard deviation(PSD)and standard deviation of MHR(±MHR)were found in younger study group(P=0.005,r=0.481 and P=0.0074,r=0.465),whereas in the older subgroup no correlation was observed.Additionally,the randomization protocol helped in defining the role of fatigue on the HEP-FDF results.Participant for whom the HEPFDF was performed after RareBit had significantly worse results than those for whom the HEP-FDF was first.In the younger group,the MHR and±MHR depend from age in that group(P<0.05,r=0.43 and r=-0.57 respectively)while no age-dependent differences were found in HEPrelated parameters.On the contrary in the older group the MD and PSD varies with age(P<0.05,r=0.47 and r=-0.44 respectively)while the RBP parameters remained unchanged.The questionnaire showed that participants preferred RareBit over HEP-FDF in terms of a duration time,comfort,understanding of the test procedures,and ocular pain(P<0.05).CONCLUSION:The influence of patient’s fatigue should be considered during HEP-FDF examination.An overlap hypothesis should be reevaluated after determining of other factors that affect HEP-FDF and RareBit results.

Quantitative Evaluation of Flicker ERG Waveforms in Low Vision Patients

Flicker electroretinograms(FERGs)of 30Hz were recorded for 46eyes(23 cases)of low vision,including 38 eyes with retinal diseases and 8eyes with optic neuropathy,and for 39 normal eyes(33 cases).The recordedwave forms were analysed by two methods:(1)to measure the peak to peakamplitude and pseudophase directly,and(2)to measure the amplitude andphase of fundamental response component(30Hz)by discrete Fourier trans-form(DFT).The abnormality ratios between these two methods were com-pared in low vision pati...

一种基于CMOS图像传感器的flicker自动检测方法

由于交流电的能量按照正弦波的形式周期性变化,当外界光源为灯光时,在曝光时间不满足交流电能量周期的整数倍的情况下,会使图像亮度随着行数的变化产生周期性变化,动态的图像看起来有条带(banding)在表面闪烁,即产生flicker.本文详细分析了fllicker产生的原因,并提出了一种自动检测flicker的方法,能够简单而有效检测到flicker的存在并进行消除.

The motion analysis of fire video images based on moment features and flicker frequency

In this paper, motion analysis methods based on the moment features and flicker frequency features for early fire flame from ordinary CCD video camera were proposed, and in order to describe the changing of flame and disturbance of non-flame phenomena further more, the average changing pixel number of the first-order moments of consecutive flames has been defined in the moment analysis as well. The first-order moments of all kinds of flames used in our experiments present irregularly flickering, and their average changing pixel numbers of first-order moments are greater than fire-like disturbances. For the analysis of flicker frequency of flame, which is extracted and calculated in spatial domain, and therefore it is computational simple and fast. The method of extracting flicker frequency from video images is not affected by the catalogues of combustion material and distance. In experiments, we adopted two kinds of flames, i. e. , fixed flame and movable flame. Many comparing and disturbing experiments were done and verified that the methods can be used as criteria for early fire detection.

干法刻蚀工艺对TFT-LCD Flicker改善的研究

为了对TFT-LCD中的闪烁不良进行改善,本文通过研究TFT-LCD中干法刻蚀（Nplus Etch）对TFT特性的影响,以此对刻蚀条件（Power、Gas）进行优化,达到降低Photo-Ioff的目的。实验结果表明,当干法刻蚀主工艺条件为：Source/Bias=4k/5k、Press=90mT、SF6/O2=1.1k/3kml/min,AT Step条件为：Source/Bias=2k/2k、Press=100mT、SF6/O2=3k/3kmL/min时,Photo-Ioff由量产最初的58.15降至20.52,闪烁由15%-30%降至10%以下。干法刻蚀工艺条件的优化对TFT特性以及闪烁有明显改善效果。

TFT漏电流对Flicker影响及测试方法研究

薄膜晶体管(TFT)作为像素单元充放电的开关,其漏电流(Ioff)大小是影响液晶屏性能的重要参数之一。文章利用薄膜晶体管的非晶硅层为光敏材料的特点,通过液晶屏翻转实验、背光亮度变化实验、min flicker-Vcom变化实验测量了flicker的大小,验证了光照强度增强导致Ioff增加后,出现了flicker增大的现象,确定了Ioff过高导致flicker的测试方法,通过实验进一步确定了Ioff大小对flicker的影响。

A Novel Automatic Method for Removal of Flicker in Video

Intensity flicker is a common form of degradation in archived film. Most algorithms on this distortion are complicated and uncontrolled. This paper presented a discrete mathematical model of flicker, designed a block-based estimation method of the model’s parameters according to their features of intensity variation in large area. With this estimation result it constructed a compensation model to repair the current frame. This restoration approach is full automatic and the repair process of current frame does not need the information of frames behind it. The algorithm was realized to establish a simple and adjustable repair system. The experimental results show that the proposed algorithm can remove most intensity flicker and preserve the wanted effects.

基于TFT-LCD下的Flicker研究与优化

针对面板闪烁性能进行因子排查优化,着重关注材料相关因素的研究,使面板闪烁性能得以提升,总体跨阶得到增大。通过对TFT-LCD面板闪烁性能进行评估优化,包括评估手法建立、性能仿真模拟以及样品性能量测等,收敛性能优化方向,最终结合实验产品测试验证,提出了面板闪烁性能提升的优化方向。而相较于常规电性,包括器件漏流、器件电容(Cst)的优化方向,本文的研究内容更关注材料的研究优化,具体为液晶响应时间参数等的研究优化,而其主要研究手法为对不同响应时间液晶下面板的闪烁性能仿真、实际性能测量以及亮度探测等。研究发现,随着液晶响应时间参数从8 ms增大至10 ms,其面板有效闪烁跨阶可从8阶提升至10阶。实验结果表明,面板可通过液晶材料响应时间的参数优化提升面板闪烁性能。

The theory of critical flicker fusion frequency and its application in cataracts

Background:Due to media opacity,it is usually difficult to accurately evaluate the postoperative visual acuity in cataracts patients.As a small and portable tool,the critical flicker fusion frequency(CFF)device reflects the temporal resolution of visual function and has been widely used in clinical research.However,poor understanding of the technique and equipment limitations have restricted its clinical application in China.Main text:There was a decrease in the CFF value in various ophthalmic diseases,indicating that the CFF is sensitive to detect visual functional changes.A number of studies have shown that the CFF test can accurately distinguish patients with simple cataracts from those with cataracts combined with fundus disease,and,as a visual test,it can more accurately predict postoperative visual acuity without being affected by media opacity.This study comprehensive reviews the basic principles of CFF and its application in ophthalmology,especially in cataracts.Conclusions:As one of the tools for dynamic visual function detection,the CFF test could help doctors to assess the possible presence of fundus disease in cataracts patients,especially in eyes with dense cataracts,and more precisely provide a reasonable visual prognosis than other available visual tests.

多频谐和与噪声作用下Flickering振子的安全盆侵蚀与混沌

研究了催化反应Flickering振子在多频率确定性谐和外力和有界随机噪声联合作用下,系统安全盆的侵蚀和混沌现象.将Melnikov方法推广到包含有限多个频率外力和随机噪声联合作用的情形,推导出了系统的随机Melnikov过程,根据Melnikov过程在均方意义上出现简单零点的条件给出了系统出现混沌的临界值,然后用数值模拟方法计算了系统的安全盆分岔点.结果表明,由于随机扰动的影响,系统的安全盆分岔点发生了偏移,并且使得混沌容易发生.同时证明,激励频率数目的增加扩大了参数空间上的混沌区域,也使得安全盆分岔提前发生,系统变得不安全.

文艺中的真理——间谍小说、幽灵书写与闪烁主体

艺术与真理的关系,自古至今向来是聚讼纷争的主题。在当今这个数字合成异常兴盛的时代,这个问题再度引发我们深思。要对此进行回应,首先要突破真与假之间的二元对立,进而将其纳入到复杂的互渗、交织和转化的动态关联中。文学创作尤其是间谍小说为审视此种关系提供了可资借鉴的线索。以勒卡雷为代表的当代间谍小说,不仅深刻延续了克拉考尔等学者所阐释的对空洞现实的诊视,更是围绕背叛这个要点引发我们重思主体性与自由这个根本的主题。结合海德格尔晚期对无基和离基的思辨,以及德里达对幽灵书写的阐发,我们试图将间谍小说中所塑造的背叛性主体视作数字时代见证真理、探索自由的未来可能。

光色周期变化对视觉疲劳影响的研究

本研究旨在探究道路照明中光色及其周期性变化对驾驶员视觉疲劳的影响。通过在高速动态条件下进行视觉特性研究,分析了综合条件下光谱光色与视觉疲劳之间的关系,并从抑制视觉疲劳的角度对光谱进行了筛选。利用闪光融合频率值对被试的视觉疲劳程度进行了量化,测试了三种不同的光色以及五组不同光色变化周期对视觉疲劳程度的影响。研究结果表明,相较于白光,蓝光光谱更具有抑制驾驶员视觉疲劳的效果;而90 s的光色变化周期对驾驶员视觉疲劳抑制效果最为显著。

红外焦平面探测器复合条件工作点闪元标定方法

针对闪元传统标定方法的不足,提出一种结合灰度域图像和能量域图像进行复合条件工作点闪元标定的方法。该方法解决了单一工作点对闪元激发条件不够充分和探测器非均匀性所造成的闪元漏检等问题。实验验证表明,单一工作点上闪元检测率平均提高了12.49%,与传统方法相比,整体闪元检测率提高了9.41%。本文所提方法有效提高了闪元的检出率。