In an optical communication link between an optical ground station and a geostationary satellite the main problems appear in the uplink and are due to beam wander and to scintillation. Reliable methods for modeling both effects simultaneously are needed to provide an accurate tool with which the robustness of the communication channel can be tested. Numerical tools, especially the split-step method (also referred to as the fast-Fourier-transform beam propagation method), have demonstrated their ability to deal with problems of optical propagation during atmospheric turbulence. However, obtaining statistically significant results with this technique is computationally intensive. We present an analytical-numerical hybrid technique that provides good information on the variance in optical irradiance with an important saving of time and computational resources.
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http://dx.doi.org/10.1364/ao.43.003866 | DOI Listing |
PLoS One
January 2025
Division of Kinesiology and Health, University of Wyoming, Laramie, WY, United States of America.
The inversion effect in biological motion suggests that presenting a point-light display (PLD) in an inverted orientation impairs the observer's ability to perceive the movement, likely due to the observer's unfamiliarity with the dynamic characteristics of inverted motion. Vertical dancers (VDs), accustomed to performing and perceiving others to perform dance movements in an inverted orientation while being suspended in the air, offer a unique perspective on this phenomenon. A previous study showed that VDs were more sensitive to the artificial inversion of PLDs depicting dance movements when compared to typical and non-dancers if given sufficient dynamic information.
View Article and Find Full Text PDFJ Dent Sci
January 2025
School of Dentistry, National Yang Ming Chiao Tung University, Taipei, Taiwan.
Background/purpose: Identifying crestal bone level (CBL) on the buccal and lingual aspects poses challenges in conventional dental radiographs. Given that optical coherence tomography (OCT) has the capability to non-invasively provide in-depth information about the periodontium, this in vitro study aimed to assess whether OCT can effectively identify periodontal landmarks and measure CBL in the presence of gingiva.
Materials And Methods: An in-house handheld scanning probe connected to a 1310-nm swept-source OCT (SS-OCT) system, along with self-developed algorithms were employed to measure the CBL in dental models with artificial gingiva.
Chemistry
January 2025
Jadavpur University, Chemistry, 188 Raja S. C. Mallick Road, 700032, Kolkata, INDIA.
Two π-radical complexes containing bisazo-aromatic-centered radical anion (1•-) were synthesized through in-situ electron transfer from metal-to-ligand using [IrI] and 2-(2-Pyridylazo)azobenzene (1) in inert hydrocarbon solvent. These are characterized as diradical [IrIII(1•-)2]+[2]+ and monoradical [IrIII(1•-)Cl2(PPh3)] 3. In contrast, a rare metal-mediated hydrolytic cleavage of the C(sp2)-N bond occurred in protic solvent resulting in quaternary radical complex [IrIII(1•-)(1')(PPh3)]+(4)+.
View Article and Find Full Text PDFACS Cent Sci
January 2025
Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States.
In quantum information science and sensing, electron spins are often purified into a specific polarization through an optical-spin interface, a process known as optically detected magnetic resonance (ODMR). Diamond-NV centers and transition metals are both excellent platforms for these so-called color centers, while metal-free molecular analogues are also gaining popularity for their extended polarization lifetimes, milder environmental impacts, and reduced costs. In our earlier attempt at designing such organic high-spin π-diradicals, we proposed to spin-polarize by shelving triplet = ±1 populations as singlets.
View Article and Find Full Text PDFEPJ Quantum Technol
January 2025
Institute for Quantum Computing and Department of Physics & Astronomy, University of Waterloo, 200 University Ave W, Waterloo, N2L 3G1 Ontario Canada.
Satellite-based quantum communication channels are important for ultra-long distances. Given the short duration of a satellite pass, it can be challenging to efficiently connect multiple users of a city-wide network while the satellite is passing over that area. We propose a network with dual-functionality: during a brief satellite pass, the ground network is configured as a multipoint-to-point topology where all ground nodes establish entanglement with a satellite receiver.
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