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The human circadian system responds to light as low as 30 photopic lux. Furthermore, recent evidence shows that there are huge individual differences in light sensitivity, which may help to explain why some people are more susceptible to sleep and circadian disruption than others. The biological mechanisms underlying the differences in light sensitivity remain largely unknown. A key variable of interest in understanding these individual differences in light sensitivity is biological sex. It is possible that in humans, males and females differ in their sensitivity to light, but the evidence is inconclusive. This is in part due to the historic exclusion of women in biomedical research. Hormonal fluctuations across the menstrual cycle in women has often been cited as a confound by researchers. Attitudes, however, are changing with funding and publication agencies advocating for more inclusive research frameworks and mandating that women and minorities participate in scientific research studies. In this article, we distill the existing knowledge regarding the relationship between light and the menstrual cycle. There is some evidence of a relationship between light and the menstrual cycle, but the nature of this relationship seems dependent on the timing of the light source (sunlight, moonlight, and electric light at night). Light sensitivity may be influenced by biological sex and menstrual phase but there might not be any effect at all. To better understand the relationship between light, the circadian system, and the menstrual cycle, future research needs to be designed thoughtfully, conducted rigorously, and reported transparently. [ABSTRACT FROM AUTHOR]

Activated Astrocytes Attenuate Neocortical Seizures in Rodent Models Through Driving Na(+)-K(+)-ATPase Zhao J, Sun J, Zheng Y, Zheng Y, Shao Y, Li Y, Fei F, Xu C, Liu X, Wang S, Ruan Y, Liu J, Duan S, Chen Z, Wang Y. Nat Commun. 2022;13(1):7136. doi:10.1038/s41467-022-34662-2 Epileptic seizures are widely regarded to occur as a result of the excitation-inhibition imbalance from a neuro-centric view. Although astrocyte-neuron interactions are increasingly recognized in seizure, elementary questions about the causal role of astrocytes in seizure remain unanswered. Here we show that optogenetic activation of channelrhodopsin-2-expressing astrocytes effectively attenuates neocortical seizures in rodent models. This anti-seizure effect is independent from classical calcium signaling, and instead related to astrocytic Na+-K+-ATPase-mediated buffering K+, which activity-dependently inhibits firing in highly active pyramidal neurons during seizure. Compared with inhibition of pyramidal neurons, astrocyte stimulation exhibits anti-seizure effects with several advantages, including a wider therapeutic window, large-space efficacy, and minimal side effects. Finally, optogenetic-driven astrocytic Na+-K+-ATPase shows promising therapeutic effects in a chronic focal cortical dysplasia epilepsy model. Together, we uncover a promising anti-seizure strategy with optogenetic control of astrocytic Na+-K+-ATPase activity, providing alternative ideas and a potential target for the treatment of intractable epilepsy. [ABSTRACT FROM AUTHOR]

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000–0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra. [ABSTRACT FROM AUTHOR]

The structural design of vehicles plays an important role in improving vehicle safety and driving performance. In this study, the frame structure of a van-type electric truck was taken as a research object. Stress, strain, and modal analyses of this frame structure were performed using Abaqus, a finite element software, to verify the rationality and safety of the structural design. The frame structure was optimized by numerical analysis. The fourth beam was moved 524 mm forward between the installation points of the power battery pack and the rear lifting lug of the front leaf spring. Results showed that the optimized frame bending, the full-load braking condition, and the full-load torsional operating condition stresses decreased by 44.499%, 23.364%, and 31.303%, respectively. The bending stiffness of an optimized frame increased by 4.026%, whereas the front and rear torsional stiffnesses increased by 4.442% and 4.092%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the modelling, design and power management of a hybrid energy storage system for a three-wheeled light electric vehicle under Indian driving conditions. The hybrid energy storage system described in this paper is characterized by effective coupling of Li-ion battery (primary energy source) and ultracapacitor (auxiliary source) interfaced with an efficient bi-directional converter. A design methodology related to vehicle modelling, choice of motor rating, converter design, sizing of Li-ion battery and ultracapacitor pack for the Indian driving cycle are presented. An improved real-time power-split management control strategy is proposed for proper power flow control of the hybrid energy storage system under various operating modes. The hybridized energy storage system with proposed control strategy improves the life of the battery and helps in effective utilization of the ultracapacitor. Furthermore, a relative comparison of the hybrid energy storage system with the battery energy storage system based on battery parameters and capital cost is also presented. Simulations are carried out in MATLAB/Simulink environment to verify the effectiveness of the proposed control strategy with modelled system components of three-wheeled light electric vehicle. A downscaled experimental prototype is built to validate the power-split between hybrid energy storage systems. [ABSTRACT FROM AUTHOR]

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production. [ABSTRACT FROM AUTHOR]

Within the human population, there is large interindividual variability in the timing of sleep and circadian rhythms. This variability has been attributed to individual differences in sleep physiology, circadian physiology, and/or light exposure. Recent experimental evidence suggests that the latter is necessary to evoke large interindividual differences in sleep and circadian timing. We used a validated model of human sleep and circadian physiology to test the hypothesis that intrinsic differences in sleep and circadian timing are amplified by self-selected use of artificial light sources. We tested the model under 2 conditions motivated by an experimental study (Wright et al., 2013): (1) a “natural” light cycle, and (2) a “realistic” light cycle that included attenuation of light due to living indoors when natural light levels are high and use of electric light when natural light levels are low. Within these conditions, we determined the relationship between intrinsic circadian period (within the range of 23.7-24.6 h) and timing of sleep onset, sleep offset, and circadian rhythms. In addition, we simulated a work week, with fixed wake time for 5 days and free sleep times on weekends. Under both conditions, a longer intrinsic period resulted in later sleep and circadian timing. Compared to the natural condition, the realistic condition evoked more than double the variation in sleep timing across the physiological range of intrinsic circadian periods. Model predictions closely matched data from the experimental study. We found that if the intrinsic circadian period was long (>24.2 h) under the realistic condition, there was significant mismatch in sleep timing between weekdays and weekends, which is known as social jetlag. These findings indicate that individual tendencies to have very delayed schedules can be greatly amplified by self-selected modifications to the natural light/dark cycle. This has important implications for therapeutic treatment of advanced or delayed sleep phase disorders. [ABSTRACT FROM AUTHOR]

Solar Electric Lighting Company (SELCO) was established in 1995 to serve the energy needs of people living at the base of the pyramid in Karnataka, India. The CEO, Dr Satish Hande, focused on developing need-based customized solar energy products for off-grid customers. During the initial years, the company faced financial problems to meet its operational needs, which was eventually overcome. Solar Electric Lighting Company came up with several innovative products that increased productivity of customers. Though the products sold were priced low, care was taken to ensure that product quality was not compromised. The company subsequently faced several challenges. The appointment of dealers in lieu of its own branches did not deliver desired results. Increase in input costs landed SELCO in losses. Pressure from investors for profits when the company was facing financial crisis was the toughest of them all. Having overcome the obstacles, SELCO became profitable, expanded operations in six states of India and installed 200,000 solar lighting systems in a period of two decades. Several growth options presented themselves to Dr Hande. The most prominent being the need to make a choice of staying focused on customized products for the poor or cater to the upmarket, high-growth and profitable segment. [ABSTRACT FROM AUTHOR]

Drawing from ethnographic research in Canadian off-grid homes, this paper examines the notion of visual comfort. Like other types of comfort, visual comfort is an affective sensibility whose intensity and achievement are highly variable. Through their unique historical trajectories grid-connected homes have achieved and normalized visual comfort in particular ways, but--as the experiences of off-grid homes show--in no way is domestic visual comfort achievable only by flicking on an electric lightbulb powered by distant sociotechnical assemblages. Comfort is, in fact, not a uniform experience and off-gridders' practices show vividly what it means to achieve it differently--in variable intensities and through alternative entanglements of nature and culture. In particular, we argue that off-gridders' comfort is a direct reflection of their involvement in its production, ensuing from their participation in electricity generation. [ABSTRACT FROM AUTHOR]

In Hong Kong, many buildings are high-rise blocks constructed close to each other resulting in severe sky obstructions, more particularly for rooms at the lower floors. Innovative daylighting technologies that transport natural light from outside towards the inner part of deep plan rooms are appropriate devices to improve daylight uniformity and visual comfort. Good visual effects and less lighting energy use may result if proper designs are employed. This paper studies the performance of light redirection systems via scale model under real sky conditions. The results demonstrate that laser cut panels can generally increase the interior daylight in the rear of the scale model room, improve the daylight uniformity and have the potential to reduce the electric lighting energy use. [ABSTRACT FROM AUTHOR]

The amount of energy used to light homes in the UK continues to rise, despite the availability of compact fluorescent light (CFL) bulbs and significant policy efforts to reduce energy demand for domestic lighting. This paper examines household lighting demand, in the UK, from a socio-technical perspective, drawing on recent in-depth interview data. This research indicates that mood lighting is becoming increasingly significant, that a desire to have stylish interiors can override environmental principles, and that household lighting practices are heavily influenced by the media. The paper concludes that lighting policy must place greater emphasis on engaging with those involved in the design and promotion of household lighting, if we are to significantly reduce energy demand in this sector. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the effect of the color of light in a room on muscular strength and power. A convenience sample of 18 men (M age = 20.4 yr., SD = 1.2) performed a modified Wingate Anaerobic Cycle Test for muscular power and a hand grip strength test in each of the following conditions: red, blue, and white (neutral) ambient light. A repeated-measures multivariate analysis of variance indicated that average muscular power was significantly higher when performing the test in the room with red light compared to rooms lit with blue light or white light. The results also indicated that grip strength was significantly higher in the room lit with white light as compared to the room lit with blue light. [ABSTRACT FROM AUTHOR]

Solar energy conversion systems and daylighting schemes are recognized as important strategies to generate clean energy, reduce peak electrical and cooling demands, and save overall building electricity expenditures. A solar façade is a building component generating electricity via photovoltaic (PV) modules and allowing daylight entering into the interior spaces to reduce electric lighting use. A key design issue for such façades is determining the overall energy benefits. The work for estimating building energy performances and savings using these building components is presented. The computer simulation tool, EnergyPlus, was used to demonstrate the likely electricity generation and saving, peak air-conditioning load, and electrical demand reductions for the façades with various window and PV panel areas. The weather database in 1989 was employed for the analysis. Important features for daylighting schemes and implications for building integrated photovoltaic designs were highlighted and elaborated. The environmental benefits and cost indications were also considered. The findings showed that proper solar façade designs could significantly contribute to environmental, energy, and economic aspects. [ABSTRACT FROM AUTHOR]

Since its invention, electric lighting has had a decisive impact on the psychogeography of urban space. Concentrating on the period from 1880 to World War II, the author argues that electrical lighting has been a major factor in the emergence of modern urban environments, in which the traditional function of architecture as a stable ground has increasingly given way to a growing mutability of forms and fluidity of appearances. This tendency both paralleled and converged with the effects of modern media technologies such as cinema, contributing to the emergence of a new environment characterized by "relational space," in which the city is increasingly defined by the overlap of material and immaterial spatial regimes. [ABSTRACT FROM AUTHOR]

The article examines the influence of electric light on the media theories of Canadian scholar and philosopher Marshall McLuhan. It describes how McLuhan viewed electric light has having no other medium as its content as well as having the ability to change human affairs. The article goes on to discuss how McLuhan stated the transformative powers of electric light were key to understanding the effects of mass media on everyday life.