A theory of moving form perception: Synergy between masking, perceptual grouping, and motion computation in retinotopic and non-retinotopic representations

Because object and self-motion are ubiquitous in natural viewing conditions, understanding how the human visual system achieves a relatively clear perception for moving objects is a fundamental problem in visual perception. Several studies have shown that the visible persistence of a briefly presented stationary stimulus is approximately 120 ms under normal viewing conditions. Based on this duration of visible persistence, we would expect moving objects to appear highly blurred. However, in human vision, objects in motion typically appear relatively sharp and clear. We suggest that clarity of form in dynamic viewing is achieved by a synergy between masking, perceptual grouping, and motion computation across retinotopic and non-retinotopic representations. We also argue that dissociations observed in masking are essential to create and maintain this synergy

Structure and Functions of Pediatric Aerodigestive Programs: A Consensus Statement

Aerodigestive programs provide coordinated interdisciplinary care to pediatric patients with complex congenital or acquired conditions affecting breathing, swallowing, and growth. Although there has been a proliferation of programs, as well as national meetings, interest groups and early research activity, there is, as of yet, no consensus definition of an aerodigestive patient, standardized structure, and functions of an aerodigestive program or a blueprint for research prioritization. The Delphi method was used by a multidisciplinary and multi-institutional panel of aerodigestive providers to obtain consensus on 4 broad content areas related to aerodigestive care: (1) definition of an aerodigestive patient, (2) essential construct and functions of an aerodigestive program, (3) identification of aerodigestive research priorities, and (4) evaluation and recognition of aerodigestive programs and future directions. After 3 iterations of survey, consensus was obtained by either a supermajority of 75% or stability in median ranking on 33 of 36 items. This included a standard definition of an aerodigestive patient, level of participation of specific pediatric disciplines in a program, essential components of the care cycle and functions of the program, feeding and swallowing assessment and therapy, procedural scope and volume, research priorities and outcome measures, certification, coding, and funding. We propose the first consensus definition of the aerodigestive care model with specific recommendations regarding associated personnel, infrastructure, research, and outcome measures. We hope that this may provide an initial framework to further standardize care, develop clinical guidelines, and improve outcomes for aerodigestive patients

Effects of Structure on the Activity, Selectivity, and Stability of Pt-Sn-DeAlBEA for Propane Dehydrogenation

Recent research has found that dealuminated zeolite BEA (DeAlBEA) is an attractive support for the dispersion of Pt and PtSn species that serve as catalysts for propane dehydrogenation (PDH). In this study, we report the preparation, structural characterization, and PDH activities of Pt-Sn-DeAlBEA catalysts as a function of the Pt/Al ratio (here Al represents the amount of Al present in the parent zeolite H-BEA). The support Sn-DeAlBEA was prepared by introduction of Sn to DeAlBEA. Characterization of this material by X-ray absorption spectroscopy (XAS) and UV–vis spectroscopy revealed that the Sn incorporated into the BEA framework as Sn(IV) cations. Pt-Sn-DeAlBEA catalysts were prepared with Pt/Al ratios (0.001–0.026) and were characterized with infrared (IR) spectroscopy of adsorbed probe molecules and XAS to understand the effect of changing Pt loading on the structure of Pt in Pt-Sn-DeAlBEA. Pt dispersion on DeAlBEA (i.e., Pt-DeAlBEA) produced Pt nanoparticles with an average Pt–Pt coordination number of 9 (∼25 Å) for Pt/Al ratios of 0.001 and above. By contrast, dispersion of Pt on Sn-DeAlBEA (Sn/Al = 0.15) produced Pt oligomers with an average Pt–Pt coordination number of 3 for Pt/Al = 0.001, but for Pt/Al ratios >0.013, Pt nanoparticles formed with a Pt–Pt coordination number of 9. Pt-Sn-DeAlBEA exhibited high selectivity to propene (>97%) and high dehydrogenation rates. Forward rate constants were calculated and compared with values determined for various Pt and PtSn catalysts reported in the literature. The Pt-Sn-DeAlBEA catalysts prepared in this study exhibited significantly higher forward rate constants than those previously reported for Pt and PtSn catalysts. The kinetics of PDH were measured for Pt-Sn-DeAlBEA catalysts with different Pt/Al ratios but identical Sn/Al ratios. In all cases, the kinetics are described by a Langmuir–Hinshelwood rate expression, which is first order in propane and is inhibited by propane adsorption. The similarity of the apparent activation energies and enthalpies of propane adsorption for all three catalysts suggests that the active species are very small Pt3Sn clusters strongly bound to the framework of DeAlBEA

Treatment of human lens epithelium with high levels of nanoceria leads to reactive oxygen species mediated apoptosis

Nanoceria (cerium oxide nanoparticles) have been shown to protect human lens epithelial cells (HLECs) from oxidative stress when used at low concentrations. However, there is a lack of understanding about the mechanism of the cytotoxic and genotoxic effects of nanoceria when used at higher concentrations. Here, we investigated the impact of 24-hour exposure to nanoceria in HLECs. Nanoceria’s effects on basal reactive oxygen species (ROS), mitochondrial morphology, membrane potential, ATP, genotoxicity, caspase activation and apoptotic hallmarks were investigated. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) studies on isolated mitochondria revealed significant uptake and localization of nanoceria in the mitochondria. At high nanoceria concentrations (400 µg mL−1), intracellular levels of ROS were increased and the HLECs exhibited classical hallmarks of apoptosis. These findings concur with the cells maintaining normal ATP levels necessary to execute the apoptotic process. These results highlight the need for nanoceria dose-effect studies on a range of cells and tissues to identify therapeutic concentrations in vitro or in viv