Light Environment Research Articles

Evaluating the impact of road lighting on pedestrian reassurance through the day-dark approach

A field study in the urban area of Ljubljana, Slovenia, explored the impact of variations in lighting parameters on pedestrian perceptions of safety, visual comfort and risk. Utilising the day-dark approach with 35 participants, this research evaluates differences in perception under daytime and after dark (but with road lighting) environments to determine the optimal lighting conditions. The results suggested that a minimum horizontal illuminance of 1.8 lx, corresponding to a day-dark differential of 0.5 on a 5-point scale, and a minimum luminance of about 0.15 cd m−2 were optimal for perceived safety and comfort. The results suggest that minimum illuminance provided a more effective predictor of pedestrian reassurance than did the other lighting parameters considered.

Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests

Abstract Tropical forest understories tend to be light‐limited. The red‐to‐far‐red ratio (R:FR) is a useful and reliable index of light quality and its spatial variability can influence competition between native and non‐native seedlings. While per cent light transmittance has been quantified in some Hawaiian lowland wet forests (HLWF), no information exists on how the spatial distribution of understorey light varies in relation to species invasion, or if patterns of seedling regeneration and light are linked. We measured the R:FR of light in the understorey to assess light quality in three HLWF forest types: native‐dominated, partially invaded and Psidium cattleyanum‐ (strawberry guava) dominated to quantify light quality in the understorey (0–50 cm height). We also identified relationships between light quality and native and non‐native seedling presence, diversity and abundance. Together, these data can help to determine the restoration potential of HLWF. Linear mixed‐effect modelling showed that native‐dominated forests had significantly greater R:FR than P. cattleyanum‐dominated forests, demonstrating a transformation in the light environment with increased invasion. Heterogeneity in R:FR varied more across sites than among forest types. In both native‐dominated and partially invaded forests, there were more native seedlings in the low‐quality R:FR (0.0–0.40) category and fewer in the medium‐ (0.41–0.70), and high‐quality (≥0.71) light categories than would be expected by chance, and there were no native seedlings in the P. cattleyanum‐dominated forests. Native‐dominated forests had greater species richness and abundance of native seedlings than the partially invaded forests, likely due to propagule availability. However, the spatial clustering of seedlings, the mismatch of native seedlings in light environments less suitable, and a considerable proportion of open high‐quality microsites, highlights that conditions are not optimal for native species in HLWF in the long term. Synthesis and applications. The native‐dominated and partially invaded forests still hold conservation value, despite variation among sites. Seedling additions could be targeted to different R:FR environments and at different spatial scales, but the lack of a strong relationship between R:FR and seedling number suggests that other factors besides light quality should be considered in seedling enrichment or other management activities.

Efficacy of agomelatine on sleep disorders and lateral habenula neuronal activity in chronic restraint stress depression model mice.

Sleep disorders (SD) are one of the common manifestations of depression patients. This article aimed to explore the effect of Agomelatine (Ago) on SD in chronic restraint stress (CRS) depression model mice and its effect on the activity of neurons in the lateral habenula (LHb). 30 C57BL/6J mice were divided into normal (C57BL/6J) group, CRS group, and Ago group. CRS experiment was used to establish the depression model, and Ago was used to treat CRS mice. Based on behavioral tests in mice and electrophysiology record, SD and LHb neuron activity were assessed. The expression levels of brain-derived neurotrophic factor (BDNF) and nuclear phosphoprotein (c-Fos) in LHb were detected by Western blot (WB). As against the CRS group, the Ago group had a reduction in the immobility time during forced swimming training and an increase in the preference for sucrose in the sucrose preference test; The expression levels of c-Fos and BDNF proteins in the LHb neurons of the Ago group mice were lower than those in the CRS group (P < 0.05), and the values approached the levels of the normal control group. In both dark and light environments, the rapid eye movement (REM) sleep duration of the CRS group mice was significantly longer than that of the normal control group (P < 0.05). It was concluded that Ago may intervene in the depressive-like behavior and overall sleep patterns of CRS depression model mice by regulating the activity of LHb neurons and inhibiting the neuroinflammatory process. This provides a potential drug target for the development of new treatment strategies for depression.

How many surfaces can you distinguish by color? Real environmental lighting increases discriminability of surface colors.

Color supports object identification. However, two objects that differ in color under one light can appear indiscriminable under a second light, a phenomenon known as illuminant metamerism. Past studies evaluated the frequency of illuminant metamerism only under single, uniform illuminants. Here we used computer-graphics techniques to simulate a pair of planar surfaces placed under newly measured hyperspectral illumination maps that quantify the directional variability of real-world lighting environments. We counted the instances of illuminant metamerism that can be solved simply by viewing surfaces tilted to a different direction. Results show that most instances of illuminant metamerism can in theory be resolved for both trichromatic and dichromatic observers, suggesting that the physical directional variability available in natural lighting environments substantially mitigates the biological limitations of trichromacy or dichromacy.

Advanced understanding of the natural forces accelerating aging and release of black microplastics (tire wear particles) based on mechanism and toxicity analysis

Currently, tire wear particles (TWPs), a typical type of black microplastics (MPs), are frequently overlooked as the major source of MPs in aquatic environments. TWPs are widely distributed and exhibit complex environmental behaviors. However, how natural forces affect the aging and release behavior of TWPs at the nano(micro)scale remains inadequately explored. This study systematically investigated the aging behavior and mechanism of TWPs under the action of simulated natural light and high-temperature in both dry and wet environments, as well as the effect of aging treatment on the released leachate. The findings demonstrated that aging treatment significantly altered the physicochemical properties of TWPs, including chain scission and surface oxidation, and facilitated the release of heavy metals and organic additives in the meantime. In particular, the leaching concentration of Zn exhibited a positive linear relationship with exposure time. In the thermal-aging process, the oxidation of TWPs was primarily caused by superoxide anion (O2•-). During the photo-aging exposure, TWPs exhibited heightened electron-donating capacity, resulting in the formation of more O2•- and singlet oxygen (1O2) to attack TWPs. Moreover, the analysis of leachate produced under light and high-temperature conditions suggested that heavy metals exerted low ecological risks in water. Nonetheless, the photo-aging process enhanced the toxicity of released leachate to L929 cells, which could be attributed to highly toxic additive transformation products (such as HMMM-411 and 6PPD-Q) and more heavy metals. These findings shed light on the fate of TWPs and the ecological risks posed by aged TWPs in aquatic environments.

A framework of insole blanking robot based on adaptive edge detection and FSPS-BIT* path planning

Insole blanking production technology plays a vital role in contemporary machining and manufacturing industries. Existing insole blanking production models have limitations because most robots are required to accurately position the workpiece to a predetermined location, and special auxiliary equipment is usually required to ensure the precise positioning of the robot. In this paper, we present an adaptive blanking robotic system for different lighting environments, which consists of an industrial robot arm, an RGB-D camera configuration, and a customized insole blanking table and mold. We introduce an innovative edge detection framework that utilizes color features and morphological parameters optimized through particle swarm optimization (PSO) techniques to Adaptive recognition of insole edge contours. A path planning framework based on FSPS-BIT* is also introduced, which integrates the BIT* algorithm with the FSPS algorithm for efficient path planning of the robotic arm.

Chromatic acclimation in cyanobacteria renders robust photosynthesis and fitness in dynamic light environment: Recent advances and future perspectives.

Cyanobacteria are photoautotrophic organisms that use light and water as a source of energy and electrons, respectively, to fix atmospheric carbon dioxide and release oxygen as a by-product during photosynthesis. However, photosynthesis and fitness of organisms are challenged by seasonal and diurnal fluctuations in light environments. Also, the distribution of cyanobacteria in a water column is subject to changes in the light regime. The quality and quantity of light change significantly in low and bright light environments that either limit photochemistry or result in photoinhibition due to an excess amount of light reaching reaction centers. Therefore, cyanobacteria have to adjust their light-harvesting machinery and cell morphology for the optimal harvesting of light. This adjustment of light-harvesting involves remodeling of the light-harvesting complex called phycobilisome or incorporation of chlorophyll molecules such as chlorophyll d and f into their light-harvesting machinery. Thus, photoacclimation responses of cyanobacteria at the level of pigment composition and cell morphology maximize their photosynthetic ability and fitness under a dynamic light environment. Cyanobacteria exhibit different types of photoacclimation responses that are commonly known as chromatic acclimation (CA). In this work, we discuss different types of CA reported in cyanobacteria and present a molecular mechanism of well-known type 3 CA where phycoerythrin and phycocyanin of phycobilisome changes according to light signals. We also include other aspects of type 3 CA that have been recently studied at a molecular level and highlight the importance of morphogenes, cytoskeleton, and carboxysome proteins. In summary, CA gives a unique competitive benefit to cyanobacteria by increasing their resource utilization ability and fitness.

Ecological, genetic and geographical divergence explain differences in colouration among sunbird species (Nectariniidae).

How extravagant ornamental traits evolve is a key question in evolutionary biology. Bird plumages are among the most elaborate ornaments, displaying almost all colours of the rainbow. Why and how birds evolved to be so colourful remains an open question with multiple and sometimes competing hypotheses. Different colours in different patches (i.e. body parts) might have different functions and thus result from different forms of selection (e.g. natural vs. sexual selection). Here we test the influence of three factors on colour diversity in sunbirds: (1) geographical distance, (2) differences in light environment and (3) phylogenetic distances. We show that both natural and sexual selection affect the evolution of sunbird colouration, but that their extent and direction differs between sexes, and varies with the extent of species overlap and across different patches on the body. Even though overlap in light environment partially explains colour differences among species, no colour metric (brightness, hue or chroma) covaries with light environment. Our results suggest that multiple forms of selection influence the colouration of different colour patches in different ways across an organism's body, highlighting the need to investigate colouration as a network of individual but inter-connected colour patches. These results are likely to be generalizable across the multitude of colourful animals.

Evaluation of the roles of brassinosteroid, gibberellin and auxin for tomato internode elongation in response to low red:far-red light.

In this study, we explore the interplay between the plant hormones gibberellins (GA), brassinosteroids (BR), and Indole-3-Acetic Acid (IAA) in their collective impact on plant shade avoidance elongation under varying light conditions. We focus particularly on low Red:Far-red (R:FR) light conditions achieved by supplementing the background light with FR. We characterized the tomato internode response to low R:FR and, with RNA-seq analysis, we were able to identify some of the potential regulatory hormonal pathways. Through a series of exogenous pharmacological modulations of GA, IAA, and BR, we demonstrate that GA and BR are sufficient but also necessary for inducing stem elongation under low R:FR light conditions. Intriguingly, while IAA alone shows limited effects, its combination with GA yields significant elongation, suggesting a nuanced hormonal balance. Furthermore, we unveil the complex interplay of these hormones under light with low R:FR, where the suppression of one hormone's effect can be compensated by the others. This study provides insights into the hormonal mechanisms governing plant adaptation to light, highlighting the intricate and adaptable nature of plant growth responses. Our findings have far-reaching implications for agricultural practices, offering potential strategies for optimizing plant growth and productivity in various lighting environments.

Developing time-resolved x-ray diffraction diagnostics at the National Ignition Facility (invited).

As part of a program to measure phase transition timescales in materials under dynamic compression, we have designed new x-ray imaging diagnostics to record multiple x-ray diffraction measurements during a single laser-driven experiment. Our design places several ns-gated hybrid CMOS (hCMOS) sensors within a few cm of a laser-driven target. The sensors must be protected from an extremely harsh environment, including debris, electromagnetic pulses, and unconverted laser light. Another key challenge is reducing the x-ray background relative to the faint diffraction signal. Building on the success of our predecessor (Target Diffraction In Situ), we implemented a staged approach to platform development. First, we built a demonstration diagnostic (Gated Diffraction Development Diagnostic) with two hCMOS sensors to confirm we could adequately protect them from the harsh environment and also acquire acceptable diffraction data. This allowed the team to quickly assess the risks and address the most significant challenges. We also collected scientifically useful data during development. Leveraging what we learned, we recently developed a much more ambitious instrument (Flexible Imaging Diffraction Diagnostic for Laser Experiments) that can field up to eight hCMOS sensors in a flexible geometry and participate in back-to-back shots at the National Ignition Facility (NIF). The design also allows for future iterations, such as faster hCMOS sensors and an embedded x-ray streak camera. The enhanced capabilities of the new instrument required a much more complex design, and the unexpected issues encountered on the first few shots at NIF remind us that complexity has consequences. Our progress in addressing these challenges is described herein, as is our current focus on improving data quality by reducing x-ray background and quantifying the uncertainties of our diffraction measurements.

Effect of light environment controlled by red and blue LEDs on the growth of Lactuca genetic resources

Effect of light environment controlled by red and blue LEDs on the growth of <i>Lactuca</i> genetic resources

Computer vision that can ‘see’ in the dark

Insufficient lighting environment has raised challenges for night shift workers’ safety monitoring. Thus, we have developed a computer vision-based algorithm recognizing 11 actions based on action recognition in dark (ARID) dataset. A hybrid model of integrating convolutional neural network (CNN) into YOLOv7 has been proposed. YOLOv7 is an algorithm designed for real-time object detection in image or video, for fast and accurate detection in applications such as autonomous vehicles and surveillance systems. In this work, video in dark environment has first been enhanced using CNN algorithm before feeding into YOLOv7 network for activity recognition. Adaptive gamma intensity correction (GIC) has been integrated to further improving the overall result. The proposed model has been evaluated over different enhancement modes. The proposed model is able to handle dark video frames with 74.95% Top-1 accuracy with fast processing speed of 93.99 ms/frame on a 4 GB RTX 3050 graphical processing unit (GPU) and 17.59 ms/frame on 16 GB Tesla T4 GPU. The base size of the proposed model is tiny, only 74.8 MB, but with 36.54 M of total parameters indicating that it has more capacity to learn more meaningful information with limited hardware resources.

Efficacy of Light and Odor Barriers in Controlling Insect Pest Evasion by Modulating Light and Gas Environments

Efficacy of Light and Odor Barriers in Controlling Insect Pest Evasion by Modulating Light and Gas Environments

The impact of Artificial Light at Night (ALAN) on biodiversity: flora and fauna at Kebun Raya Bogor

Background: Artificial light at night (ALAN) poses significant ecological challenges by altering the natural light environment. Plants and animals have evolved to depend on natural light cycles for their physiological and behavioral processes. This study investigates the impact of ALAN on the biodiversity of flora and fauna at Kebun Raya Bogor (KRB), a key site for understanding these effects. Methods: This research employs a literature review approach to analyze the effects of ALAN on flora and fauna. By examining existing studies and data, the review focuses on changes in plant physiology, including photosynthesis and growth patterns, as well as alterations in animal behavior, such as foraging, mating, and migration. The review synthesizes findings from various sources to assess the impact of ALAN on biodiversity at KRB. Results: Findings indicate that ALAN disrupts plant photosynthesis and growth, particularly affecting deciduous trees and altering reproductive and growth patterns. For fauna, ALAN significantly impacts the behavior of nocturnal species such as bats and birds, affecting their feeding, mating, and migratory patterns. The disruption in natural light cycles due to ALAN leads to ecological imbalances and may compromise the biodiversity of KRB.

Observing fish behavior in towed fishing gear—is there an influence of artificial light?

Fish behavior is important to consider when developing selective fishing gear. In studies designed to investigate the size selective properties of towed fishing gears such as trawls, fish behavior is mainly documented by underwater video recordings. Because fishing gear can be operated at great depths or in other low light environments, artificial light is often required for underwater recordings. However, artificial light can influence fish behavior, which casts doubt on the validity of behavioral observations obtained in the presence of artificial light. However, removing artificial light disables video recordings and the possibility to study fish behavior in relation to selectivity devices towed fishing gears in low light environments. To date, little is known about the extent to which artificial light used for video observations affects fish behavior with respect to fishing gear. Therefore, we conducted fishing trials in the Barents Sea demersal trawl fishery to assess the effect of light sources on fish behavior by using size selectivity results in towed fishing gears. We found that the behavior of cod (Gadus morhua) was unaffected by the light sources, whereas the behavior of haddock (Melanogrammus aeglefinus), saithe (Pollachius virens) and redfish (Sebastes spp.) significantly changed when red light and white light were employed. Our results also demonstrated significant differences in fish behavior between white and red light.

Corrosion behavior of additively manufactured FeCrAl in out-of-pile light water reactor environments

Iron-Chromium-Aluminum (FeCrAl) alloys are candidate materials for the cladding of light water reactor (LWR) fuels. The FeCrAl alloys in general range in Cr composition from 12% (C26M) to 21% (APMT). In this work, the general corrosion behavior of Additively Manufactured (AM) C26M coupons was compared to the behavior of traditional Powder Metallurgy (PM) coupons. Immersion testing were conducted for 12 months at 288 °C and 330 °C in pure water containing either oxygen or hydrogen. Results show that the mass change of AM specimens in hydrogenated water was like the mass change of PM specimens. In oxygenated water, the mass change of AM coupons was higher and less reproducible than for the PM coupons. Porosity in the AM specimens makes their behavior less predictable in high-temperature water.

The influence of lighting and thermal environments on sleep and cognitive function in older adults

The influence of lighting and thermal environments on sleep and cognitive function in older adults

Research on an Indoor Light Environment Comfort Evaluation Index Based on Electroencephalogram and Pupil Signals

With the development of modern technology, many people work for a long time around various artificial light sources and electronic equipment, causing them to feel discomfort in their eyes and even eye diseases. The industry currently lacks an objective quantitative environmental–visual comfort index that combines subjective and objective indicators. For this experiment, objective eye movement and electroencephalogram (EEG) signals were collected in combination with a subjective questionnaire survey and a preference inquiry for comprehensive data mining. Finally, the results on a Likert scale show that high screen brightness can reduce the visual fatigue of subjects under high illuminance and high correlated color temperature (CCT). Pupil data show that, under medium and high ambient illuminance, visual perception sensitivity is more likely to be stimulated, and visual fatigue is more likely to deepen. EEG data show that visual fatigue is related to illuminance and screen brightness. On this basis, this study proposes a new evaluation index, the visual comfort level (0.6404 average at a low screen brightness, 0.4218 average at a medium screen brightness, and 0.5139 average at a high screen brightness), where a higher score for the visual comfort level represents a better visual experience. The visual comfort level provides a useful reference for enhancing the processing of multi-dimensional and biomedical signals and protecting the eyes.

Therapeutic Exercise Recognition Using a Single UWB Radar with AI-Driven Feature Fusion and ML Techniques in a Real Environment.

Physiotherapy plays a crucial role in the rehabilitation of damaged or defective organs due to injuries or illnesses, often requiring long-term supervision by a physiotherapist in clinical settings or at home. AI-based support systems have been developed to enhance the precision and effectiveness of physiotherapy, particularly during the COVID-19 pandemic. These systems, which include game-based or tele-rehabilitation monitoring using camera-based optical systems like Vicon and Microsoft Kinect, face challenges such as privacy concerns, occlusion, and sensitivity to environmental light. Non-optical sensor alternatives, such as Inertial Movement Units (IMUs), Wi-Fi, ultrasound sensors, and ultrawide band (UWB) radar, have emerged to address these issues. Although IMUs are portable and cost-effective, they suffer from disadvantages like drift over time, limited range, and susceptibility to magnetic interference. In this study, a single UWB radar was utilized to recognize five therapeutic exercises related to the upper limb, performed by 34 male volunteers in a real environment. A novel feature fusion approach was developed to extract distinguishing features for these exercises. Various machine learning methods were applied, with the EnsembleRRGraBoost ensemble method achieving the highest recognition accuracy of 99.45%. The performance of the EnsembleRRGraBoost model was further validated using five-fold cross-validation, maintaining its high accuracy.

Contrasting Dynamic Photoprotective Mechanisms under Fluctuating Light Environments between an Andean and a Mesoamerican Genotype of Phaseolus vulgaris L.

Plants have evolved various photosynthetic adaptations and photoprotective mechanisms to survive in fluctuating and extreme light environments. Many light-activated photosynthetic proteins and enzymes adjust to plant leaf anatomy and leaf pigments to facilitate these processes. Under excessive amounts of light, plants use non-photochemical quenching (NPQ) mechanisms to dissipate excess absorbed light energy as heat to prevent photoinhibition and, therefore, mitigate damage to the plant’s photosystems. In this study, we examined photosynthetic adaptations to the light environment in common beans using representative genotypes of the Andean (Calima) and the Mesoamerican (Jamapa) gene pools. We estimated their leaf chlorophyll fluorescence characteristics using dark- and light-adapted mature leaves from three-week-old plants. Our results indicated a higher chlorophyll fluorescence of the light-adapted leaves in the Mesoamerican genotype. NPQ induction was early and extended in the Andean genotype. A similar response in the Mesoamerican counterpart required high light intensity (≥1500 PAR). The NPQ relaxation was rapid in the Mesoamerican genotype (t1/2: 6.76 min) but sluggish in the Andean genotype (t1/2: 9.17 min). These results indicated variable adaptation to light environments between the two common bean genotypes and suggested different strategies for surviving fluctuating light environments that can be exploited for developing plants with environmentally efficient photosynthesis under light limitations.