We present the results from a Monte Carlo computer simulation of adaptive optics (AO) pre-compensated laser uplink propagation through the Earth's atmospheric turbulence from the ground to orbiting satellites. The simulation includes the so-called point-ahead angle and tests several potential AO mitigation modes such as tip/tilt or full AO from the downlink beam, and a laser guide star at the point ahead angle. The performance of these modes, as measured by metrics relevant for free-space optical communication, are compared with no correction and perfect correction. The aim of the study is to investigate fundamental limitations of free-space optical communications with AO pre-compensation and a point-ahead angle, therefore the results represent an upper bound of AO corrected performance, demonstrating the potential of pre-compensation technology. Performance is assessed with varying launch aperture size, wavelength, launch geometry, ground layer turbulence strength (i.e. day/night), elevation angle and satellite orbit (Low-Earth and Geostationary). By exploring this large parameter space we are able examine trends on performance with the aim of informing the design of future optical ground stations and demonstrating and quantifying the potential upper bounds of adaptive optics performance in free-space optical communications.
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http://dx.doi.org/10.1364/OE.413013 | DOI Listing |
Chem Senses
December 2024
Department of Biological Science, Florida State University, Tallahassee, FL.
Although animals can reliably locate and recognize odorants embedded in complex environments, the neural circuits for accomplishing these tasks remain incompletely understood. Adaptation is likely to be important as it could allow neurons in a brain area to adjust to the broader sensory environment. Adaptive processes must be flexible enough to allow the brain to make dynamic adjustments, while maintaining sufficient stability so that organisms do not forget important olfactory associations.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Hunan International Scientific and Technological Cooperation Base of Neurodegenerative and Neurogenetic Diseases, Xiangya Hospital, Central South University, Changsha, Hunan, China.
Background: Aging exhibits significant variation among individuals, with biological age as a more reliable predictor of current health status compared to chronological age. Predicting biological age is crucial for facilitating timely interventions aimed at improving the adaptation to the aging process. Given the intricate and multifactorial nature of aging, a scientific approach involves constructing a prediction model for biological age that incorporates multiple dimensions systematically.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Whole-Body Sensorimotor Lab, UCL Queen Square Institute of Neurology, London, UK.
Background: Posterior cortical atrophy (PCA) is often considered the most common atypical Alzheimer's disease phenotype, being characterized by progressive loss of visual and other posterior cortical functions. Early reading and other visuoperceptual difficulties prompt PCA patients presenting to eye clinics and receiving ocular misdiagnoses. Patients also report altered perception of body position- for example, difficulty locating ones' arm during dressing.
View Article and Find Full Text PDFElife
January 2025
Werner Reichardt Centre for Integrative Neuroscience, University of Tübingen, Tübingen, Germany.
Neuromodulators have major influences on the regulation of neural circuit activity across the nervous system. Nitric oxide (NO) has been shown to be a prominent neuromodulator in many circuits and has been extensively studied in the retina. Here, it has been associated with the regulation of light adaptation, gain control, and gap junctional coupling, but its effect on the retinal output, specifically on the different types of retinal ganglion cells (RGCs), is still poorly understood.
View Article and Find Full Text PDFJ Neuroophthalmol
January 2025
Scheie Eye Institute (YC, TL, SW, TP, PAA, G-sY, CAB, MAT), University of Pennsylvania, Philadelphia, Pennsylvania; Divisions of Neuro-ophthalmology (MAT), Oculoplastics (CAB), and Biostatistics (PAA, G-sY), Kansas Health Science Center, Kansas College of Osteopathic Medicine; and Kansas Health Science Center (GM), Kansas College of Osteopathic Medicine, Kansas, Missouri.
Background: To characterize the retreatment course of patients with thyroid eye disease (TED), who had reactivation after initial therapy with teprotumumab.
Methods: This was a single-center longitudinal cohort study of patients who received an initial course of teprotumumab for active TED and were followed for at least 6 months. Reactivation was defined as the increase of proptosis of 2 mm or more or an increase in Clinical Activity Score (CAS) of two points or more, as adapted from the Optic-X study.
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