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Light
\"In this book, young readers will discover interesting facts about light, and discover a variety of fun experiments to test their knowledge.\"-- Provided by publisher.
Book
Imaging by flat lens using negative refraction
The positive refractive index of conventional optical lenses means that they need curved surfaces to form an image, whereas a negative index of refraction allows a flat slab of a material to behave as a lens and focus electromagnetic waves to produce a real image.
Journal Article
Sources of light
Takes a look at sources of light, and explains the difference between things that make light and things that don't.
Book
Plasmonic Nanodomains Decorated on Two-Dimensional Oxide Semiconductors for Photonic-Assisted COsub.2 Conversion
Plasmonic nanostructures ensure the reception and harvesting of visible lights for novel photonic applications. In this area, plasmonic crystalline nanodomains decorated on the surface of two-dimensional (2D) semiconductor materials represent a new class of hybrid nanostructures. These plasmonic nanodomains activate supplementary mechanisms at material heterointerfaces, enabling the transfer of photogenerated charge carriers from plasmonic antennae into adjacent 2D semiconductors and therefore activate a wide range of visible-light assisted applications. Here, the controlled growth of crystalline plasmonic nanodomains on 2D Ga[sub.2]O[sub.3] nanosheets was achieved by sonochemical-assisted synthesis. In this technique, Ag and Se nanodomains grew on 2D surface oxide films of gallium-based alloy. The multiple contribution of plasmonic nanodomains enabled the visible-light-assisted hot-electron generation at 2D plasmonic hybrid interfaces, and therefore considerably altered the photonic properties of the 2D Ga[sub.2]O[sub.3] nanosheets. Specifically, the multiple contribution of semiconductor-plasmonic hybrid 2D heterointerfaces enabled efficient CO[sub.2] conversion through combined photocatalysis and triboelectric-activated catalysis. The solar-powered acoustic-activated conversion approach of the present study enabled us to achieve the CO[sub.2] conversion efficiency of more than 94% in the reaction chambers containing 2D Ga[sub.2]O[sub.3]-Ag nanosheets.
Journal Article
Light show
\"Light Show explores how artists working over the past fifty years have used that power to create some of the most innovative and compelling sculpture in contemporary art.\"--Page 4 of cover.
Book
Dark photon production via Formula omitted
The dark photon is a new gauge boson which arises from an extra [Formula omitted] gauge symmetry. In this paper, a novel dark photon production mechanism based on MeV-scale [Formula omitted]- [Formula omitted] collider is considered: [Formula omitted]. With the aid of PACKAGE-X, differential cross section of [Formula omitted] is obtained, as a function of the kinetic mixing parameter [Formula omitted] and dark photon mass [Formula omitted]. Taking the light-by-light scattering as background, the constraints on the dark photon parameter space for different time intervals in a MeV-scale [Formula omitted]- [Formula omitted] collider are also given.
Journal Article
The science of light
A look at the science behind the creation, travel, and appearance of light.
Book
0070 The Effects of Acute Blue Wavelength Light Exposure on Functional Brain Connectivity and Mood
Abstract
Introduction
Blue wavelength light is an effective treatment for delayed sleep phase syndrome, seasonal affective disorder and bipolar depression. The role of blue light in regulating melatonin production has been extensively studied, but other potential neurophysiological effects remain poorly understood. Some studies have suggested that daily blue light exposure may modulate functional brain responses within the amygdala and prefrontal cortex (PFC), potentially explaining blue light’s antidepressant effect. In this study we investigated the effects of a single 30-minute session of blue light exposure on functional resting state connectivity between the amygdala and PFC.
Methods
Twenty-nine healthy 18–32 year olds were randomly assigned to either receive 30 minutes of blue (n=17) or non-blue (amber) light (n=12) exposure followed by a 7-minute resting state scan. Pre- and post light exposure, participants completed the Positive and Negative Affect Scale, as a measure of state affect.
Results
Individuals who received blue versus amber light showed greater positive connectivity between the right amygdala and the left dorsolateral prefrontal cortex (DLPFC) (x=-24, y=46, z=18, k=90, volume p-FDR corrected, p<0.001). Increased amygdala-DLFC connectivity correlated with greater decreases in negative mood for the blue (ρ=-.55, p=0.03), but not the amber group. Using Granger Causality, we found that the directionality of information flow between these two areas was bidirectional (p<0.0025).
Conclusion
Blue light exposure appears to facilitate greater information flow between the amygdala and the DLPFC at rest, potentially enhancing cognitive processes that regulate arousal and mood. As blue light exposure has been shown to enhance attention and learning, using blue light exposure during practice of emotional regulation strategies, such as reappraisal, may further increase the beneficial effects of blue light on mood. In order to use blue light exposure in a more targeted manner for sleep and mood disorders, further research into the underlying neurophysiological mechanisms is needed.
Support
This research was supported by a USAMRAA grant to WDSK (W81XWH-14-1-0571) as well as by an Arizona Health Education Centers (AHEC) Research Grant to AA.
Journal Article
0079 Blue Light Exposure Enhances Neural Efficiency of the Task Positive Network During a Cognitive Interference Task
Abstract
Introduction
Light exposure has powerful effects on the circadian timing of sleep and wake, primarily through the regulation of the secretion of melatonin. However, it is becoming clear that light has additional alerting effects beyond its primary effect on the circadian system. Exposure to light, particularly blue-wavelength light, has been shown to acutely increase brain activation, alertness, and some elementary aspects of cognitive performance such as working memory and emotional anticipation during the day. Whether blue light exposure can have longer-lasting effects on brain activation and performance during more complex cognitive control tasks up to 30-minutes after light cessation is unknown.
Methods
In a sample of 30 healthy adults, we examined the effects of a single 30-minute exposure to either blue (n=14) or amber placebo (n=16) light on subsequent brain activation and performance during the Multi-Source Interference Task (MSIT) measured a half-hour after light cessation using functional magnetic resonance imaging. Mean activation in all regions showing increased task-related activation (i.e., Task Positive Network; TPN) and regions showing decreased activation (i.e., Default Mode Network; DMN) at p<.001 (FWE corrected) was extracted separately for each network in SPM12 and compared between light conditions.
Results
Performance metrics for the MSIT, including accuracy, response time, and cognitive throughput, did not differ between the blue and amber conditions, suggesting that performance was sustained equally between light conditions. However, brain activation within the TPN to the interference condition of the MSIT was significantly lower (p=.024) in the blue relative to the amber condition, with no group differences observed for suppression of the DMN.
Conclusion
Compared to amber, a single exposure to blue light was associated with enhanced neural efficiency a half-hour later as demonstrated by reduced TPN activation to achieve the same level of cognitive performance. Blue light may be an effective method for optimizing neurocognitive performance under some conditions.
Support
US Army Medical Research and Materiel Command: W81XWH-14-1-0571
Journal Article