3D shape discrimination using relative disparity derivatives

Stereopsis provides a constant feed to visual shape representation

The contribution of stereopsis in human visual shape perception was examined using stimuli with either null, normal, or reversed binocular disparity in an old/new object recognition task. The highest levels of recognition performance were observed with null and normal binocular disparity displays, which did not differ. However, reversed disparity led to significantly worse performance than either of the other display conditions. This indicates that stereopsis provides a continuous input to the mechanisms involved in shape perception.

Stereoscopic depth constancy from a different direction

To calibrate stereoscopic depth from disparity our visual system must compensate for an object's egocentric location. Ideally, the perceived three-dimensional shape and size of objects in visual space should be invariant with their location such that rigid objects have a consistent identity and shape. These percepts should be accurate enough to support both perceptual judgments and visually-guided interaction. This theoretical note reviews the relationship of stereoscopic depth constancy to the geometry of stereoscopic space and seemingly esoteric concepts like the horopter. We argue that to encompass the full scope of stereoscopic depth constancy, researchers need to consider not just distance but also direction, that is 3D egocentric location in space. Judgements of surface orientation need to take into account the shape of the horopter and the computation of metric depth (when tasks depend on it) must compensate for direction as well as distance to calibrate disparities. We show that the concept of the horopter underlies these considerations and that the relationship between depth constancy and the horopter should be more explicit in the literature.

Theoretical and practical study of the cefoxitin-Escherichia coli PBP5 complex interaction by molecular dynamics to obtain computational prototype of antimicrobial susceptibility to Gram negative bacteria

The penicillin-binding proteins (PBPs) are important biological target for new antibacterial drugs development. This study focused on molecular interaction between cefoxitin and the Escherichia coli PBP5 by molecular dynamics (MD) using hybrid quantum mechanics/molecular mechanics (QM/MM) simulations approach, searching to develop a computational simulations prototype method on antimicrobial susceptibility of gram-negative bacteria against antibiotics. Escherichia coliATCC 8739 strain susceptibility for the drugs used in the antimicrobial susceptibility testing and selection of bioactive molecules against resistant strain. The protonation revealed a deprotonate state for His146, His151, His216, and His320 residues. The complex was stabilized after 0.6 ns of MD simulation. The global interaction means for inhibition zone diameters of E. coliATCC8739 strain and cefoxitin were 24.33 mm no showing significant difference between computational and experimental methods. Our computational simulation method can reliably be performed as a molecular modeling prototype for gram-negative antimicrobial susceptibility testing bacteria.

Stereo-Curvature Aftereffect Is Due to More Than Shape Curvature Adaptation

For stereo-curvature aftereffect (sCAE), there is no agreement on whether adaptation occurs at the disparity-specified stage, the percept-specified stage, or both. Additionally, it remains uncertain whether retinal-position-dependent sCAE can be induced by possible adaptation to disparity-specified sources. Our study aimed to investigate the dependency and processing levels of adaptation underlying sCAE using dynamic spherical adaptation stimuli with static fixation. Experiment I examined the dependency by dynamically altering the location or size of adaptation stimuli. Experiment 2 investigated the adaptation levels via three sub-experiments: Experiment 2.1 examined how eccentricity influenced adaptation strength using static adaptation stimuli with different eccentricities, Experiment 2.2 tested a hypothesis about adaptation to a percept-specified primitive shape index (PSI) using dynamic size change of adaptation stimuli, and Experiment 2.3 tested another hypothesis on adapting disparity-specified average disparity information (ADI) using dynamic PSI change of adaptation stimuli. The results showed retinal-position-dependent and scale-independent sCAE. In addition to a possible eccentricity effect, the retinal-position dependence can result from ADI adaptation while the scale independence can be attributed to PSI adaptation. Therefore, sCAE is caused by adaptation at both the disparity-specified and percept-specified stages. Additionally, sCAE endows two coexisting adaptation processes with one dependent on retinal position and one independent of retinal position.