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http://dx.doi.org/10.1152/ajpcell.00494.2006 | DOI Listing |
J Comput Neurosci
January 2025
Computational Brain Science Lab, Division of Computational Science and Technology, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden.
This paper presents an in-depth theoretical analysis of the orientation selectivity properties of simple cells and complex cells, that can be well modelled by the generalized Gaussian derivative model for visual receptive fields, with the purely spatial component of the receptive fields determined by oriented affine Gaussian derivatives for different orders of spatial differentiation. A detailed mathematical analysis is presented for the three different cases of either: (i) purely spatial receptive fields, (ii) space-time separable spatio-temporal receptive fields and (iii) velocity-adapted spatio-temporal receptive fields. Closed-form theoretical expressions for the orientation selectivity curves for idealized models of simple and complex cells are derived for all these main cases, and it is shown that the orientation selectivity of the receptive fields becomes more narrow, as a scale parameter ratio , defined as the ratio between the scale parameters in the directions perpendicular to vs.
View Article and Find Full Text PDFBy utilizing the time inversion of radiation from spatial dipole arrays, we propose a method for constructing the spatial lattice-type skyrmion arrays under 4 focusing conditions, including Néel-, Bloch-, and Anti-skyrmions/merons. The Richards-Wolf vector diffraction theory is applied to analyze the radiation field emitted by dipole arrays, aiming to determine the incident field required under a high numerical aperture (NA=0.95).
View Article and Find Full Text PDFTerahertz reconfigurable intelligent surfaces (RIS) stand out from conventional phased arrays thanks to their unique electromagnetic properties and intelligent interconnect paradigms. They are a vital technology for terahertz wireless communication and radar detection systems. Compared with 1-bit coding metasurfaces, 2-bit coding metasurfaces offer significant advantages such as single beam steering and reduced quantization errors.
View Article and Find Full Text PDFMode-selective converters (MSCs) play an indispensable role in mode division multiplexing (MDM) systems, and the commonly used cascaded waveguide-based MSCs not only have a relatively large size but also increase the insertion loss and mode crosstalk during the conversion process. In this paper, a parallel six-mode-selective converter (6-MSC) is proposed to enhance the integration of the device, which consists of a photonic crystal fiber (PCF) and six step-index fibers (SIFs). Here, a PCF without any holes in the cladding is proposed.
View Article and Find Full Text PDFThis paper proposes a reflective metasurface composed of a single unit structure, yet capable of achieving precise control of two degrees of freedom. By grooving two orthogonal slots on the copper ring, it enables the independent conversion of the two orthogonal components of the incident waves. Consequently, incident linearly-polarized waves can be rotated by an arbitrary angle.
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