20 research outputs found
Nature of topological protection in photonic spin and valley Hall insulators
Recent interest in optical analogs to the quantum spin Hall and quantum valley Hall effects is driven by the
promise to establish topologically protected photonic edge modes at telecommunication and optical wavelengths
on a simple platform suitable for industrial applications. While first theoretical and experimental efforts have
been made, these approaches so far both lack a rigorous understanding of the nature of topological protection and
the limits of backscattering immunity. We here use a generic group theoretical methodology to fill this gap and
obtain general design principles for purely dielectric two-dimensional topological photonic systems. The method
comprehensively characterizes possible two-dimensional hexagonal designs and reveals their topological nature,
potential, and limits
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Diabetic Macular Edema: Current Understanding, Pharmacologic Treatment Options, and Developing Therapie
Perioperative administration of propranolol to women undergoing ovarian cancer surgery: A pilot study
A neural network model for development of reaching and pointing based on the interaction of forward and inverse transformations
Pointing is one of the communicative actions that infants acquire during their first year of life. Based on a hypothesis that early pointing is triggered by emergent reaching behavior toward objects placed at outâofâreach distances, we proposed a neural network model that acquires reaching without explicit representation of âtargetsâ. The proposed model controls a twoâjoint arm in a horizontal plane, and it learns a loop of internal forward and inverse transformations; the former predicts the visual feedback of hand position and the latter generates motor commands from the visual input through random generation of the motor commands. In the proposed model, the motor output and visual input were represented by broadly tuned neural units. Even though explicit âtargetsâ were not presented during learning, the simulation successfully generated reaching toward visually presented objects at withinâreach and outâofâreach distances