We introduce a scheme where a time-dependent source excites "complex-frequency" modes in uniform plasmonic heterostructures, enabling complete and dispersionless stopping of light pulses, resilient to realistic levels of dissipative, radiative, and surface-roughness losses. Using transparent conducting oxides at telecommunication wavelengths we show how, without increasing optical losses, multiple light pulses can decay with time precisely at their injection points, unable to propagate despite the complete absence of barriers in front or behind them. Our results theoretically demonstrate extraordinary large light-deceleration factors (of the order of 1.5×107) in integrated nanophotonic media, comparable only to those attainable with ultracold atomic vapors or with quantum coherence effects, such as coherent population oscillations, in ruby crystals.
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http://dx.doi.org/10.1103/PhysRevLett.112.167401 | DOI Listing |
Clin Cosmet Investig Dermatol
January 2025
Department of Basic Biomedical Science, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Sosnowiec, Poland.
Purpose: The aim was to quantitatively evaluate the effectiveness of LED light therapy combined with photoacceptor substances having anti-acne properties in reducing the symptoms of acne vulgaris.
Patients And Methods: 15 subjects aged 20 to 24 who suffered from moderate or severe acne lesions. The treatments were performed using a LED device (465-880 nm).
Exp Neurol
January 2025
Brain and Mind Research Institute, Department of Biology, University of Ottawa, Ottawa, Ontario, Canada. Electronic address:
Spasticity is a common comorbidity of spinal cord injury (SCI), disrupting motor function and resulting in significant discomfort. While elements of post-SCI spasticity can be assessed using pre-clinical SCI models, the robust measurement of spasticity severity can be difficult due to its periodic and spontaneous appearance. Electrical stimulation of sensory afferents can elicit spasticity-associated motor responses, such as spasms; however, placing surface electrodes on the hindlimbs of awake animals can induce stress or encumbrance that could influence the expression of behaviour.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Research Centre for Biomedical Engineering, City St George's, University of London, London, EC1V 0HB, UK.
Over the past ten years, there has been an increasing demand for reliable consumer wearables as users are inclined to monitor their health and fitness metrics in real-time, especially since the COVID-19 pandemic. Reflectance pulse oximeters in fitness trackers and smartwatches provide convenient, non-invasive SpO measurements but face challenges in achieving medical-grade accuracy, particularly due to difficulties in capturing physiological signals, which may be affected by skin pigmentation. Hence, this study sets out to investigate the influence of skin pigmentation, particularly in individuals with darker skin, on the accuracy and reliability of SpO measurement in consumer wearables that utilise reflectance pulse oximeters.
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January 2025
School of Sciences, Xi'an Technological University, Xi'an 710021, China.
A solution to address the issues of environmental light interference in Remote Photoplethysmography (rPPG) methods is proposed in this paper. First, signals from the face's region of interest (ROI) and background noise signals are simultaneously collected, and the two signals are processed by a differential to obtain a more accurate rPPG signal. This method effectively suppresses background noise and enhances signal quality.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Research Centre for Biomedical Engineering, City St George's, University of London, London EC1V 0HB, UK.
The effect of skin pigmentation on photoplethysmography and, specifically, pulse oximetry has recently received a significant amount of attention amongst researchers, especially since the COVID-19 pandemic. With most computational studies observing overestimation of arterial oxygen saturation (SpO) in individuals with darker skin, this study seeks to further investigate the root causes of these discrepancies. This study analysed intensity changes from Monte Carlo-simulated reflectance PPG signals across light, moderate, and dark skin types at oxygen saturations of 70% and 100% in MATLAB R2024a.
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