Forensic Study on Objective Evaluation of Visual Acuity of Ametropia with the Event-related Potential P3

Objective In this study,we aimed to assess the characteristics of the P3 component from an event-related potential(ERP)that was induced by visual acuity(VA)processing.Furthermore,we sought to provide electrophysiological evidence for the objective evaluation of VA.Methods We recruited 32 participants with myopia-related ametropia.They reported no other ocular diseases and had an uncorrected VA of 4.0 in both eyes.We used the block letter“E”at different visual angles and orientations as the graphic stimuli.The oddball paradigm,consisting of 4 modules,was used for ERP analysis.The standard stimuli of each module were identical,with a visual angle of 1°15′.The visual angles of the target stimuli were 1°15′,55′,24′,and 15′.The VA test was performed on each eye separately for all participants,and all characteristics of the P3 component were analyzed.Results There was no significant difference in the P3 peak letencies between the target stimulation angle 1°15′group and the 55′group,or between the target stimulation angle 24′group and the 15′group.There was a significant difference in the P3 peak letencies between the target stimulation angle 1°15′group and the 24′group as well as the 15′group.There was a significant difference in the P3 peak letencies between the target stimulation angle 55′group and the 24′group as well as the 15′group.No significant differences were observed in the P3 amplitude between modules.Conclusion In the oddball paradigm,P3 elicitation indicated a cognitive response to the target stimuli.These data showed that the characteristics of P3 can be used as an objective evaluation of VA.

Characteristics of Pattern Visual Evoked Potential in Two Eyes with Varying Visual Acuity in One Eye and Forensic Application

In this study, we aimed to study the pattern visual evoked potentials （P-VEPs） in two eyes with varying visual acuity in one eye and to provide an objective estimation of visual acuity by comparing P-VEPs in one and two eyes. Thirty subjects were chosen, who had one eye with an acuity of 5.0, 4.85, 4.6, 4.0, or scieropia and obstructed vision and the other eye with an acuity of 5.0, respectively. P-VEPs were detected under the large grating stimuli at 3x4 spatial frequency, moderate grating stimuli （12× 16 spatial frequency） and small grating stimuli （48×64 spatial frequency）. Under large grating stimuli, there was no significant difference in P100 peak latency between the groups, nor was there a significant difference between the amplitude of two eyes and the amplitude of one normal-vision eye. Under moderate and small grating stimuli, there was a significant difference in P100 peak latency between the group with both eyes having an acuity of 5.0 and the group with visual acuity below 4.0 in one eye. There was a significant difference in P100 amplitude between the group with visual acuity of 5.0 in both eyes and the group with one normal-vision eye. There was no significant difference in the amplitude of two eyes and the amplitude of one normal-vision eye between any other two groups. In forensic identification, characteristics and variability of P-VEPs in one and two eyes can be used to identify malingering or decline in visual acuity.

Effect of w(MgO)/w(Al_(2)O_(3)) ratio and basicity on microstructure and metallurgical properties of blast furnace slag

The CaO–SiO_(2)–Al_(2)O_(3)–MgO system is the main component unit in the slag formation process in blast furnace smelting.Its structural changes directly affect the high-temperature metallurgical properties of slag.Molecular dynamics simulations were thus conducted to analyze the microstructure changes of the quaternary slag system under different basicities and w(MgO)/w(Al_(2)O_(3))ratios.The changes in w(MgO)/w(Al_(2)O_(3))ratio and basicity could affect the stability of each ion-oxygen.Increasing the basicity and w(MgO)/w(Al_(2)O_(3))ratio,the average coordination number of O surrounding Si atom only changed a little and remained approximately 4,indicating that Si exists as a stable structure of the[SiO4]4−tetrahedron in the slag structure,while the average coordination number of O surrounding Al atom changed greatly from 4 to 6,which indicated that the Al existence form could be transformed from[AlO_(4)]^(5−) tetrahedron to[AlO_(5)]^(7−) pentahedron and[AlO_(6)]^(9−) octahedron.Also,the diffusion rate of ions was accelerated with the increase in w(MgO)/w(Al_(2)O_(3))ratio and basicity.Moreover,the self-diffusion coefficients of each ion were obtained,and the magnitudes were observed to be in the following order:Mg^(2+)>Ca^(2+)>Al^(3+)>Si^(4+).The calculation and analysis of the slag viscosity and activation energy of viscous flow under different basicities and w(MgO)/w(Al_(2)O_(3))ratios revealed that the metallurgical properties of slag at high temperature depend on the flow-unit diffusivity and the microstructure stability,simultaneously,the basicity should be controlled between 1.0 and 1.2,and the w(MgO)/w(Al_(2)O_(3))ratio could be controlled between 0.45 and 0.55.