Contrast Detection Learning Improves Visual Contrast Sensitivity of Cat

Psychological studies on human subjects show that contrast detection learning promote learner＇s sensitivity to visual stimulus contrast. The underlying neural mechanisms remain unknown. In this study, three cats （Felis catus） were trained to perform monocularly a contrast detection task by two-altemative forced choice method. The perceptual ability of each cat improved remarkably with learning as indicated by a significantly increased contrast sensitivity to visual stimuli. The learning effect displayed an evident specificity to the eye employed for learning but could partially transfer to the naive eye, prompting the possibility that contrast detection learning might cause neural plasticity before and after the information from both eyes are merged in the visual pathway. Further, the contrast sensitivity improvement was evident basically around the spatial frequency （SF） used for learning, which suggested that contrast detection learning effect showed, to some extent, a SF specificity. This study indicates that cat exhibits a property of contrast detection learning similar to human subjects and can be used as an animal model for subsequent investigations on the neural correlates that mediate learning-induced contrast sensitivity improvement in humans.

Multi-year Simulations and Experimental Seasonal Predictions for Rainy Seasons in China by Using a Nested Regional Climate Model (RegCM_NCC). Part Ⅰ: Sensitivity Study

A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP （Institute of Atmospheric Physics） T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year （2001 to 2004） prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process paraxneterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme （MFS） and Betts-Miller scheme （BM） for convective precipitation, the LPMI （land surface process model I） and LPMII （land surface process model Ⅱ） for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE （turbulent kinetic energy） scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 （RegCM_NCC） has been set up for climate simulations and seasonal predictions.

Spatial and temporal patterns of the sensitivity of radial growth response by Picea schrenkiana to regional climate change in the Tianshan Mountains

Climate change significantly impacts forest ecosystems in arid and semi-arid regions.However,spatiotemporal patterns of climate-sensitive changes in individual tree growth under increased climate warming and precipitation in north-west China is unclear.The dendrochronological method was used to study climate response sensitivity of radial growth of Picea schrenkiana from 158 trees at six sites during 1990-2020.The results show that climate warming and increased precipitation significantly promoted the growth of trees.The response to temperature first increased,then decreased.However,the response to increased precipitation and the self-calibrating Palmer Drought Severity Index(scPDSI)increased significantly.In most areas of the Tianshan Mountains,the proportion of trees under increased precipitation and scPDSI positive response was relatively high.Over time,small-diameter trees were strongly affected by drought stress.It is predicted that under continuous warming and increased precipitation,trees in most areas of the Tianshan Mountains,especially those with small diameters,will be more affected by precipitation.

Specificity and sensitivity of visual evoked potentials P100 latency to different events exercise

Visual evoked potentials (VEPs) are a series of signals about visual occipital cortex in response to visual stimuli and can be used as one of ob-jective non-invasive neuro-physiological pa-rameters to reflect the visual organs and central visual pathway’s functional integrity. Previous studies have shown that acute and chronic ex-ercise could affect VEPs independent from body temperature and other physiological parameters. VEPs may well be used as neuro-physiological criteria in defining the performances of the ath-letes. Different sports training have different effects on VEPs, but the results are not consis-tent. P100 latency is the representative compo-nent of VEPs and it is of high, steady amplitude and of slight intra- and inter-individual variabil-ity so that the index is most commonly used. The purpose of this study was to investigate the specificity and sensitivity of P100 latency to dif-ferent physical activities. The neural electricity device of NDI-200 was used to measure the pattern reversal VEPs of all subjects, including the values of the resting state before and after different events exercise. Different events exer-cise contained an aerobic cycloergometric ex-ercise (7 subjects were conducted to a Bruce Graded Exercise Test on the Monark Ergomedic 839E cycloergometer, THR (target heart rate) = 85% HRmax, 3 times/week, about 10 minutes once time, 6 weeks), tennis training (16 volun-teers, 2 hours/day, 3 days/week, 8 weeks), aerobic Latin exercise (7 subjects, 1 hour/day, 3 days/week, 6 weeks) and the Baduanjin of Health Qigong training (6 subjects, 1 hour/day, 3 days/week, 6 weeks). The VEPs recordings of the control groups obtained synchronized with the experimental groups. SPSS 11.5 for win-dows was used for statistical analysis. A level of P﹤0.05 was accepted as statistically significant. The VEPs P100 latency of post-exercise of all experimental groups except Baduanjin group became shorter significantly compared with those of pre-exercise (P﹤0.05). No significant difference was found between pre-and post- exercise for the control groups. This study showed that exercise could shorten the P100 la-tency significantly. Moreover, it also indicated that VEPs were sensitive to exercise to a certain extent. We concluded that VEPs might well be used as neuro-physiological criteria in defining the performances of the athletes. It was found that the VEPs P100 latency became shorter after most training programs;furthermore, it demon-strated that P100 latency of VEPs had little specificity to different events.

Macular thickness as a predictor of loss of visual sensitivity in ethambutol-induced optic neuropathy

Ethambutol is a common cause of drug-related optic neuropathy.Prediction of the onset of ethambutol-induced optic neuropathy and consequent drug withdrawal may be an effective method to stop visual loss.Previous studies have shown that structural injury to the optic nerve occurred earlier than the damage to visual function.Therefore,we decided to detect structural biomarkers marking visual field loss in early stage ethambutol-induced optic neuropathy.The thickness of peripapillary retinal nerve fiber layer,macular thickness and visual sensitivity loss would be observed in 11 ethambutol-induced optic neuropathy patients（22 eyes） using optical coherence tomography.Twenty-four healthy age-and sex-matched participants（48 eyes） were used as controls.Results demonstrated that the temporal peripapillary retinal nerve fiber layer thickness and average macular thickness were thinner in patients with ethambutol-induced optic neuropathy compared with healthy controls.The average macular thickness was strongly positively correlated with central visual sensitivity loss（r2=0.878,P=0.000）.These findings suggest that optical coherence tomography can be used to efficiently screen patients.Macular thickness loss could be a potential factor for predicting the onset of ethambutol-induced optic neuropathy.

基于Visual MODFLOW大水矿山深部开采矿坑涌水量预测

矿产资源的不断开发导致矿坑涌、突水现象愈加频繁,此类问题多发生于大水矿山,为更好指导大水矿山深部开采工作,准确预测矿山深部开采矿坑涌水量至关重要。结合某矿区勘察资料、水文地质条件和观测井实测水位数据,利用Visual MODFLOW软件建立矿区水文地质数值模型,进行稳态与非稳态校正以及相关参数敏感性分析;根据该矿区-150 m水平矿坑真实涌水量拟合分析Drain模块水力传导系数值,运用识别后模型对矿山深部开采矿坑涌水量预测,结果表明-200、-250、-300、-350 m等不同水平矿坑正常涌水量为17209.82、18896.20、21299.31、23494.10 m^(3)/d,预测结果可为矿山防治水工作提供依据,以及为工程安全开挖提供保障。

Predictive visual field outcomes after optic chiasm decompressive surgery by retinal vessels parameters using optical coherence tomography angiography

AIM:To evaluate the predictive value of superficial retinal capillary plexus(SRCP)and radial peripapillary capillary(RPC)for visual field recovery after optic cross decompression and compare them with peripapillary nerve fiber layer(pRNFL)and ganglion cell complex(GCC).METHODS:This prospective longitudinal observational study included patients with chiasmal compression due to sellar region mass scheduled for decompressive surgery.Generalized estimating equations were used to compare retinal vessel density and retinal layer thickness preand post-operatively and with healthy controls.Logistic regression models were used to assess the relationship between preoperative GCC,pRNFL,SRCP,and RPC parameters and visual field recovery after surgery.RESULTS:The study included 43 eyes of 24 patients and 48 eyes of 24 healthy controls.Preoperative RPC and SRCP vessel density and pRNFL and GCC thickness were lower than healthy controls and higher than postoperative values.The best predictive GCC and pRNFL models were based on the superior GCC[area under the curve(AUC)=0.866]and the tempo-inferior pRNFL(AUC=0.824),and the best predictive SRCP and RPC models were based on the nasal SRCP(AUC=0.718)and tempo-inferior RPC(AUC=0.825).There was no statistical difference in the predictive value of the superior GCC,tempo-inferior pRNFL,and tempo-inferior RPC(all P>0.05).CONCLUSION:Compression of the optic chiasm by tumors in the saddle area can reduce retinal thickness and blood perfusion.This reduction persists despite the recovery of the visual field after decompression surgery.GCC,pRNFL,and RPC can be used as sensitive predictors of visual field recovery after decompression surgery.

Visual navigation in orchard based on multiple images at different shooting angles

The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve autonomous navigation in orchard,a visual navigation method based on multiple images at different shooting angles is proposed in this paper.A dynamic image capturing device is designed for camera installation and multiple images can be shot at different angles.Firstly,the obtained orchard images are classified into sky and soil detection stage.Each image is transformed to HSV space and initially segmented into sky,canopy and soil regions by median filtering and morphological processing.Secondly,the sky and soil regions are extracted by the maximum connected region algorithm,and the region edges are detected and filtered by the Canny operator.Thirdly,the navigation line in the current frame is extracted by fitting the region coordinate points.Then the dynamic weighted filtering algorithm is used to extract the navigation line for the soil and sky detection stage,respectively,and the navigation line for the sky detection stage is mirrored to the soil region.Finally,the Kalman filter algorithm is used to fuse and extract the final navigation path.The test results on 200 images show that the accuracy of visual navigation path fitting is 95.5%,and single frame image processing costs 60 ms,which meets the real-time and robustness requirements of navigation.The visual navigation experiments in Camellia oleifera orchard show that when the driving speed is 0.6 m/s,the maximum tracking offset of visual navigation in weed-free and weedy environments is 0.14 m and 0.24 m,respectively,and the RMSE is 30 mm and 55 mm,respectively.

RESEARCH ON IMPERFECTION SENSITIVE REGION OF SINGLE-LAYER LATTICED DOMES

The concept of the imperfection sensitive region is given. The advanced stochastic imperfection method is used to research the imperfection sensitive region of single-layer latticed domes. Taking a K6 single-layer latticed dome with a diameter of 50 m as an example, its imperfection sensitive region is made up of the first 12 kinds of joints. The influence of the imperfections of support joints on the stability of the K6 single-layer latticed dome is negligible. Influences of the joint imperfections of the main rib and the secondary rib on the structural stability are similar. The initial deviations of these joints all greatly lower the critical load of the dome. Results show that the method can analyze the structural imperfection sensitive region quantitatively and accurately.

Visual MODFLOW在郎家水源地供水预测中的应用

为确定郎家水源地20年内地下水水质、水量是否满足供水要求,构建了数学模型并运用Visual MODFLOW进行了模拟预测。模拟预测结果表明,所建立的数学模型能够反映真实的地下水状况,当浑河来水为Ⅲ类水质时,郎家水源地水质能够满足供水要求,但是应合理控制浑河来水,以保持水源地水质。

基于Visual MODFLOW的地下水流数值模拟——以四川垮梁子滑坡为例

以四川省中江县冯店镇垮梁子滑坡为研究对象,通过工程地质勘察查明了研究区基本地层结构,结合水文地质调查与现场试验(电阻率成像法、直流充电法、示踪试验、注水试验等)获得的水文地质参数和边界条件,建立了滑坡区水文地质概念模型,并运用Visual MODFLOW软件构建了垮梁子岩质滑坡体中地下水各向异性三维渗流模型,经过模型的识别及验证,对模型的水文地质参数进行了敏感性分析。结果显示:渗透系数对模型的准确性影响较大,后缘水位对滑坡的稳定性起关键作用。模拟结果可以对垮梁子滑坡预警预报模型的建立提供科学依据。

Simulations of a Hydrological Model as Coupled to a Regional Climate Model

Considering a detailed hydrologic model in the land surface scheme helps to improve the simulation of regional hydro-climatology. A hydrologic model, which includes spatial heterogeneities in precipitation and infiltration, is constructed and incorporated into the land surface scheme BATS. Via the coupled-model (i.e., a regional climate model) simulations, the following major conclusions are obtained: the simulation of surface hydrology is sensitive to the inclusion of heterogeneities in precipitation and infiltration; the runoff ratio is increased after considering the infiltration heterogeneity, a result which is more consistent with the observations of surface moisture balance over humid areas; the introduction of the parameterization of infiltration heterogeneity can have a greater influence on the regional hydro-climatology than the precipitation heterogeneity; and the consideration of the impermeable fraction for the region reveals some features that are closer to the trend of aridification over northern China.

Contrast visual acuity after multifocal intraocular lens implantation: aspheric versus spherical design

AIM: To evaluate contrast visual acuity(CVA) after implantation of an aspheric apodized diffractive intraocular lens(IOL) or a spherical apodized diffractive IOL in cataract surgery. ·METHODS: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL(30 eyes) and a spherical AcrySof ReSTOR SN60D3 IOL(30 eyes). CVA with best distance correction was measured at 4 contrast levels(100%,25%,10% and 5%) under 3 levels of chart luminance [250,85 and 25 candelas per square meter(cd/m2)] using a multi-functional visual acuity tester(MFVA-100). ·RESULTS: At 12 months after surgery,there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m2(P100% =0.875 and P25% =0.057) and 85cd/m2(P100% =0.198 and P25% =0.193) between the aspheric group and the spherical group. However,the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m2(P10% =0.042 and P5% = 0.007) and 85cd/m2(P10% =0.002 and P5%=0.039). Under the luminance level of 25cd/m 2,no significant differences was found in the 100% CVA between the 2 group(P100% = 0.245),while aspheric group had better visual acuity in the remaining 3 contracts(P25% =0.023,P10% =0.026 and P5% = 0.002,respectively). ·CONCULSION: The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.

Visual performance after conventional LASIK and wavefront-guided LASIK with iris-registration:results at 1 year

AIM:To compare visual performance of wavefrontguided laser in situ keratomileusis(LASIK) with iris-registration(Wg-LASIK group) and conventional LASIK(LASIK group) one year after surgery and analyze the correlation between wavefront aberrations and visual performance.·METHODS:Eight hundred and fifty-two myopic eyes of 430 patients were enrolled in this prospective study and divided into two groups:Wg-LASIK group(436eyes) and LASIK group(416 eyes).A Wavescan Wavefront aberrometer was used to analyze Zernike coefficients and the root-mean-square(RMS) of higher order aberrations,and Optec 6500 visual function instrument was used to measure contrast sensitivity(CS)before and 3,6,12 months after surgery.·RESULTS:The mean spherical equivalent(SE) in WgLASIK group was significantly better than those in LASIK group one year after surgery(P =0.024).Wg-LASIK eyes showed better CS values than LASIK eyes at all spatial frequencies with and without glare after surgery(P all【0.01).Moreover,the increase of higher RMS(RMSh),coma,RMS3,RMS4,RMS5 in Wg-LASIK group were significantly lower than those in LASIK group 1 year after surgery(P all 【0.05).The increase of coma,spherical aberration(SA),RMS3 and RMS4 in Wg-LASIK and coma and RMS3 in LASIK group were negatively correlated with reduction of contrast sensitivity 1 year after surgery.·CONCLUSION:A significant better visual performance is got in Wg-LASIK group compared with LASIK group 1year after surgery,and the Wg-LASIK is particularly suitable for eyes with high-magnitude RMSh.

Sensitivity and vulnerability of water resources in the arid Shiyang River Basin of Northwest China

The sensitivity and vulnerability of water resources to climate change is difficult to assess. In this study, we used a conceptual hydrologic model to investigate the sensitivity of streamflow to climate change. We also pro- posed a framework to evaluate the vulnerability of water resources in arid regions. We applied this framework to a case study of the Shiyang River Basin in Northwest China. Results showed that the precipitation and streamflow in Shiyang River Basin exhibited no significant trends of change from 1956 to 2010. In the past five decades, however, the temperature increased significantly by 0.37℃ per decade. According to the sensitivity assessment, a 10% in- crease in precipitation and a 1℃ increase in temperature altered mean annual streamflow by averages of 14.6% and -0.5%, respectively, from 1988 to 2005. In the 2000s, the calculated vulnerability of water resources in Shiyang River Basin was more than 0.95, indicating severe vulnerability. The increase in the amount of precipitation and the imple- mentation of water-saving measures can reduce the vulnerability of water resources in the future; if precipitation in- creases by 10% per decade and the use of irrigation water decreases by 15% in the 2030s, the evaluated value of water resources vulnerability will be reduced to 0.79. However, the region remains highly vulnerable. The proposed framework for vulnerability assessment can be applied to the arid regions in Northwest China, and the results of our efforts can identify adaptation strategies and improve the management of water resources in such regions.

Study on the Effects of Land Surface Heterogeneities in Temperature and Moisture on Annual Scale Regional Climate Simulation

The ＂combined approach＂, which is suitable to represent subgrid land surface heterogeneity in both interpatch and intra-patch variabilities, is employed in the BiOsphere/Atmosphere Transfer Scheme （BATS） as a land surface component of the regional climate model RegCM3 to consider the heterogeneities in temperature and moisture at the land surface, and then annual-scale simulations for 5 years （1988-1992） were conducted. Results showed that on the annual scale, the model＇s response to the heterogeneities is quite sensitive, and that the effect of the temperature heterogeneity （TH） is more pronounced than the moisture heterogeneity （MH）. On the intraannual scale, TH may lead to more （less） precipitation in warm （cold） seasons, and hence lead to larger intraannual variability in precipitation; the major MH effects may be lagged by about 1 month during the warm, rainy seasons, inducing -6% more precipitation for some sub-regions. Additionally, the modeled climate for the northern sub-regions shows larger sensitivities to the land surface heterogeneities than those for the southern sub-regions. Since state-of-art land surface models seldom account for surface intra-patch variabilities, this study emphasizes the importance of including this kind of variability in the land surface models.

Effects of upper lid blepharoplasty on visual quality in patients with lash ptosis and dermatochalasis

AIM：To assess the effects of upper lid blepharoplasty on visual quality.METHODS：Seventy-three eyelids of 39 patients were subjected to upper lid blepharoplasty.Pre- and postoperative contrast sensitivity,visual acuity,vertical palpebral aperture and the degree of lash ptosis were measured.RESULTS：The mean log contrast sensitivities under photopic（P =0.017） and scotopic conditions（P =0.009）were improved after surgery,and these differences were significant.The degree of lash ptosis was also decreased after blepharoplasty（P〈0.001）.CONCLUSION：In our study,a significant increase in contrast sensitivity was found after surgery.These results suggest that upper lid blepharoplasty can be helpful for improving visual quality.

A Visual Attention Model for Robot Object Tracking

Inspired by human behaviors, a robot object tracking model is proposed on the basis of visual attention mechanism, which is fit for the theory of topological perception. The model integrates the image-driven, bottom-up attention and the object-driven, top-down attention, whereas the previous attention model has mostly focused on either the bottom-up or top-down attention. By the bottom-up component, the whole scene is segmented into the ground region and the salient regions. Guided by top-down strategy which is achieved by a topological graph, the object regions are separated from the salient regions. The salient regions except the object regions are the barrier regions. In order to estimate the model, a mobile robot platform is developed, on which some experiments are implemented. The experimental results indicate that processing an image with a resolution of 752 × 480 pixels takes less than 200 ms and the object regions are unabridged. The analysis obtained by comparing the proposed model with the existing model demonstrates that the proposed model has some advantages in robot object tracking in terms of speed and efficiency.

CNOP-P-based parameter sensitivity for double-gyre variation in ROMS with simulated annealing algorithm

Reducing the error of sensitive parameters by studying the parameters sensitivity can reduce the uncertainty of the model,while simulating double-gyre variation in Regional Ocean Modeling System(ROMS).Conditional Nonlinear Optimal Perturbation related to Parameter(CNOP-P)is an effective method of studying the parameters sensitivity,which represents a type of parameter error with maximum nonlinear development at the prediction time.Intelligent algorithms have been widely applied to solving Conditional Nonlinear Optimal Perturbation(CNOP).In the paper,we proposed an improved simulated annealing(SA)algorithm to solve CNOP-P to get the optimal parameters error,studied the sensitivity of the single parameter and the combination of multiple parameters and verified the effect of reducing the error of sensitive parameters on reducing the uncertainty of model simulation.Specifically,we firstly found the non-period oscillation of kinetic energy time series of double gyre variation,then extracted two transition periods,which are respectively from high energy to low energy and from low energy to high energy.For every transition period,three parameters,respectively wind amplitude(WD),viscosity coefficient(VC)and linear bottom drag coefficient(RDRG),were studied by CNOP-P solved with SA algorithm.Finally,for sensitive parameters,their effect on model simulation is verified.Experiments results showed that the sensitivity order is WD>VC>>RDRG,the effect of the combination of multiple sensitive parameters is greater than that of single parameter superposition and the reduction of error of sensitive parameters can effectively reduce model prediction error which confirmed the importance of sensitive parameters analysis.

NEW VISUAL PERCEPTUAL POOLING STRATEGY FOR IMAGE QUALITY ASSESSMENT

Most of Image Quality Assessment (IQA) metrics consist of two processes. In the first process, quality map of image is measured locally. In the second process, the last quality score is converted from the quality map by using the pooling strategy. The first process had been made effective and significant progresses, while the second process was always done in simple ways. In the second process of the pooling strategy, the optimal perceptual pooling weights should be determined and computed according to Human Visual System (HVS). Thus, a reliable spatial pooling mathematical model based on HVS is an important issue worthy of study. In this paper, a new Visual Perceptual Pooling Strategy (VPPS) for IQA is presented based on contrast sensitivity and luminance sensitivity of HVS. Experimental results with the LIVE database show that the visual perceptual weights, obtained by the proposed pooling strategy, can effectively and significantly improve the performances of the IQA metrics with Mean Structural SIMilarity (MSSIM) or Phase Quantization Code (PQC). It is confirmed that the proposed VPPS demonstrates promising results for improving the performances of existing IQA metrics.