Compact Fluorescent Research Articles

Exploring the Hidden World of Lighting Flicker with a High-Speed Camera

Alternating current can result in flickering—or pulsing—in the brightness of light emitted by luminaires. Lighting flicker typically occurs in the range of 100 to 140 cycles per second (Hz), which is too fast for visual perception by most organisms. However, evidence indicates that many organisms perceive flicker with non-visual photoreceptors present on the retinas. Exposure to flickering lights at night disrupts the circadian rhythm of organisms, leading to symptoms similar to blue light exposure at night. The traditional method for detecting flickering is with a flickermeter held near a single light. In this paper, we explore the use of high-speed camera data in the collection of temporal profiles for groups of luminaires simultaneously at distances ranging from several meters to several kilometers. Temporal profiles are extracted for individual lighting features and the full scene. The identification of luminaire types is based on their spectral signatures. With the camera data, it is possible to identify flickering and non-flickering lights, to determine the flicker frequency, to calculate percent flicker and the flicker index, and to identify groups of lights whose flickers are synchronized. Both flickering and non-flickering luminaires can be found for LED, metal halide, fluorescent, and compact fluorescent lights. To date, flickering has been detected in all of the incandescent, high-pressure sodium, and low-pressure sodium luminaires that we measured. We found that flicker synchronization is often present for lights installed within a single facility and also for strings of streetlights. We also found that flicker exposure can come from the light reflected off of the earth’s surface. Luminaires designed to illuminate large areas often saturate high-speed camera data collection. This saturation can be reduced or eliminated using neutral density filters on the camera. Published experimental data on the impacts of flicker on organisms remains sparse. Many studies have drawn inferences on the impacts of spectral and lighting brightness on organisms without controlling for flicker. Our conclusion is that lighting flicker is a type of light pollution. The use of high-speed camera data makes it easier to include flicker as a variable in studies regarding the impacts of lighting on organisms.

Effect of night-break on growth and flower production in Kalanchoe

Kalanchoe blossfeldiana is a popular potted flowering plant with extended flowering periods and low demand for nutrients and water. Understanding photoperiodic response is a prerequisite for the management of the flowering period in photoperiodic crops like Kalanchoe. The night-break treatments were provided by an artificial light source (CFL bulbs) starting from 7th October 2019 for 20 (7th October - 26th October), 30 (7th October - 5th November) and 40 (7th October - 15th November) days as night interruption (NI) for 30 min. and 60 min. from 11:30 PM to 00:00 AM and 11:30 PM to 00:30 AM. Exposing the plants to a 60 min. night interruption for 20 days has proven to be crucial in achieving essential qualitative criteria for potted plants, specifically ensuring compact plant growth with minimal plant height (26.20 cm) and a controlled plant spread (19.17 cm). The maximum number of days to flower bud appearance (138.07 days), days to colour break stage (203.79 days) and days to 50% opening of flowers (232.23 days) was under 60 min. of night interruption for 40 days. Therefore, delayed flower production in Kalanchoe for up to 45 days can be achieved by 60 min. of night interruption for 40 days along with acceptable quality pot plants. A significant amount of anthocyanins and total phenols reported with photoperiodic treatment confirms that photoperiod influenced the biosynthesis of anthocyanin and phenoliccompounds in Kalanchoe.

The benefits and limitations of using blue-blocking filters – a review of results of clinical trials

Introduction and aim. Blue light is part of the natural light spectrum and plays a role in regulating the circadian rhythm. However, with the increasing use of electronic devices and energy-efficient lighting emitting high levels of artificial blue light, concerns are raised regarding its potential effect on human health. Blue-blocking filters have been developed and are adver tised as a solution to be used in spectacles or intraocular lenses. This review aims to provide an in-depth analysis of the use of blue-blocking filters based on the results of clinical trials. Material and methods. This review included relevant original papers reporting on clinical trial results from PubMed, Science Direct, and Google Scholar databases using specified keywords. Analysis of the literature. Trials conducted with patients reveal mixed results, with some showing no significant changes in vision and reading abilities, while others indicating potential limitations such as reduced contrast vision. However, blue-blocking filters have demonstrated potential benefits in improving sleep quality and mood, particularly in patients with sleep disturbances or psychiatric disorders. The efficacy of blue-blocking filters in mitigating symptoms of digital eye strain remains inconclusive. Conclusion. Overall, this paper provides a comprehensive assessment of the benefits and limitations associated with the use of blue-blocking filters, highlighting the need for further investigation in certain areas.

Low UV radiation influenced DNA methylation, gene regulation, cell proliferation, viability, and biochemical differentiation in the cell suspension cultures of Cannabis indica

The effect of low artificial Ultraviolet (UV) on the DNA methylation remains controversial. This study addresses how differential photoperiods of UV radiation affect the biochemical and molecular behaviors of Cannabis indica cell suspension cultures. The cell suspensions were illuminated with the compact fluorescent lamps (CFL), emitting a combination of 10% UVB, 30% UVA, and the rest visible wavelengths for 0, 4, 8, and 16 h. The applied photoperiods influenced cell morphological characteristics. The 4 h photoperiod was the most effective treatment for improving biomass, growth index and cell viability percentage while these indices remained non-significant in the 16 h treatment. The methylation-sensitive amplified polymorphism (MASP) assay revealed that the UV radiation was epigenetically accompanied by DNA hypermethylation. The light-treated cells significantly displayed higher relative expression of the cannabidiolic‌ acid synthase (CBDAS) and delta9-tetrahydrocannabinolic acid synthase (THCAS) genes about 4-fold. The expression of the olivetolic acid cyclase (OAC) and olivetol synthase (OLS) genes exhibited an upward trend in response to the UV radiation. The light treatments also enhanced the proline content and protein concentration. The 4 h illumination was significantly capable of improving the cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) concentrations, in contrast with 16 h. By increasing the illumination exposure time, the activity of the phenylalanine ammonia-lyase (PAL) enzyme linearly upregulated. The highest amounts of the phenylpropanoid derivatives were observed in the cells cultured under the radiation for 4 h. Taken collective, artificial UV radiation can induce DNA methylation modifications and impact biochemical and molecular differentiation in the cell suspensions in a photoperiod-dependent manner.

An Experimental Analysis of Three-Phase Low-Voltage Power Factor Controllers Used in a Deforming Regime

In industry, to improve the power factor in low-voltage power substations, a power factor controller (the most used method) can be installed which connects capacitors banks (connected, or not, with coils) in the electrical installation. The most important parameters of power engineering are the power factors that indicate the efficiency of energy use. Currently, many non-linear consumers (more single-phase than three-phase) are used on low voltages. Harmonics (currents and/or voltages) are the most important dynamic component of power quality, affecting electrical equipment performance and also reducing power factors. The purpose of this analysis is to increase the displacement power factor and to decrease the total harmonic distortion (for the current) in the conditions where there are linear and non-linear consumers, where the power factor must be improved with capacitors banks. Relevant different consumers have been selected for both the industry and the home sector, as follows: inductive motors that are linear, inductive consumers, compact fluorescent lamps that are non-linear, and capacitive consumers. This analysis was carried out depending on the number of steps used for the power factor controller, the values of the capacitors banks, the AC reactor (connected in series with all consumers), and the LC shunt filters. For a slight deformation regime, a large number of capacitors banks with different values ensure a finer adjustment of the displacement factor. The maximum number of steps that regulators can command should not necessarily be used (the reliability of the installation decreases with the increase in the number of capacitors banks), but a reduced number of steps can be used, which can lead to higher values of displacement power factors. To improve the deforming regime and to increase the displacement power factor, the use of LC shunt filters, connected to a small number of steps, will also increase the displacement power factor (over 0.9) and decrease the total harmonic distortion (up to 7–10%) for the current. Weaker results were obtained with AC reactors connected to the power supply phases of consumers and, if a larger number of stages were used, to which LC shunt filters were connected, these filters become difficult to calibrate (resonances occur).

Pulsed operation of perovskite LEDs: a study on the role of mobile ions

ABSTRACT Metal halide perovskite light-emitting diodes (PeLEDs) are a promising technology for energy-efficient and cost-effective lighting and displays, thanks to their tunable color emission, high brightness, color purity and low-temperature fabrication. However, the mixed ionic-electronic conductivity of perovskite materials presents unique challenges, as ionic defects can redistribute under operation, affecting the energy landscape and charge recombination mechanisms. Our drift-diffusion simulations establish a connection between the transient electroluminescence (TrEL) signals of PeLEDs under pulsed operation and the influence of mobile ions. We find that the TrEL plateau value’s dependence on the duty cycle and end-of-pulse overshoot can be explained by the time-varying distribution of ionic defects. The inclusion of mobile ions is crucial to understand the TrEL response. Moreover, the simulations highlight injection barriers at the perovskite/charge-transport layer interfaces, such as is the case for the hole transport layer in our example, as a significant source of non-radiative charge recombination. These findings contribute to the understanding of transient ionic processes in perovskite-based devices.

A COMPREHENSIVE REVIEW OF ENERGY-EFFICIENT LIGHTING TECHNOLOGIES AND TRENDS

Energy-efficient lighting technologies have undergone significant advancements in recent years, driving a transformation in the lighting industry. This comprehensive review explores various energy-efficient lighting technologies and trends, aiming to provide insights into their applications, benefits, and future prospects. The review begins with an overview of energy-efficient lighting technologies, including light-emitting diodes (LEDs), compact fluorescent lamps (CFLs), and advanced lighting controls. It examines the key characteristics and advantages of each technology, highlighting their energy-saving potential and environmental benefits. Next, the review discusses the trends shaping the energy-efficient lighting market, such as the transition to solid-state lighting, the emergence of smart lighting systems, and the growing emphasis on human-centric lighting design. It explores how these trends are driving innovation and transforming the way lighting is used and managed in various settings. The review also examines the benefits of energy-efficient lighting technologies, including reduced energy consumption, lower maintenance costs, and enhanced lighting quality. It discusses how these technologies contribute to energy conservation, sustainability, and improved lighting experiences for users. Furthermore, the review discusses the challenges and barriers to the widespread adoption of energy-efficient lighting technologies, such as high upfront costs, technical complexity, and the need for regulatory support. It explores strategies to overcome these challenges and accelerate the adoption of energy-efficient lighting solutions. Finally, the review provides insights into the future outlook for energy-efficient lighting technologies, highlighting emerging trends, innovative applications, and potential areas for further research and development. It emphasizes the importance of continued innovation and collaboration in driving the evolution of energy-efficient lighting technologies towards a more sustainable and efficient future. In summary, this comprehensive review offers a detailed analysis of energy-efficient lighting technologies and trends, providing valuable insights for researchers, policymakers, and industry stakeholders seeking to understand and leverage the potential of energy-efficient lighting for a sustainable future.
 Keywords: Energy-Efficient, Lighting, Technologies, Trend, Review.

A Field Study of Individual, Energy-Efficient, and Human-Centered Indoor Electric Lighting: Its Impact on Comfort and Visual Performance in an Open-Plan Office Part 1

In this field study, we examined the impact of human-centered lighting on an open-plan office environment, involving the participation of sixty office workers. The objective was to investigate the effects of the Circadian Stimulus (CS) and Equivalent Melanopic Lux (EML) metrics. This study took place at Istanbul Technical University in Istanbul, Turkey. The office was equipped with single Correlated Color Temperature (CCT) light emitting diode (LED) sources, featuring two different light beam distributions: Direct Suspended Linear (L1) and Direct and Indirect Suspended Linear (L2). To minimize energy consumption, we proposed simulations for a suspended individual lighting system. The office workers were invited to complete visual cognitive performance tests, proofreading tasks, and the Karolinska Sleepiness Scale (KSS) test to measure alertness. Additionally, participants were asked to provide feedback on the comfort criteria associated with the designed human-centered lighting concept. The preliminary findings from part 1 of this field study shed light on the potential of office lighting modifications in enhancing energy efficiency and meeting the standards set by WELL v2 2023 Q4 and UL Design Guideline 24480 (2019). Part 2 of this study will further optimize the proposed lighting quality concept to determine the most suitable individual lighting solution for office workers.

Aspects Regarding of Passive Filters Sustainability for Non-Linear Single-Phase Consumers

The efficient use of electrical energy (an important component of sustainability) has become increasingly important for electrical consumers (industrial and non-industrial) as we face the challenges of climate change and the need to protect the environment. This theme is essential for guaranteeing a secure and sustainable future for both present and future generations. The power quality and the efficiency of electrical energy are connected to each other. Some power quality problems are caused by natural and unpredictable events, but many disturbances affecting power quality are caused by suppliers and consumers. One of the most important parameters in power engineering is the power factor, which indicates the degree of efficient use of electrical energy. Harmonics is the most important dynamic component of power quality, which affects the operation of electrical equipment and, at the same time, reduces the power factor. Harmonic sources in power systems are generally associated with nonlinear loads. To analyze the operating of passive filters (series L, shunt LC, T type LCL), two groups of experiments (relevant consumers were chosen for the industry as well as from the household sector) were carried out with single-phase nonlinear consumers: in the first group of experiments, a variable-frequency drive is used to supply a three-phase induction motor with variable load; in the second group of experiments, compact fluorescent lamps and LED lamps were used. Following the experiments, it was found that the difficulty of calibrating coils (to size a filter), especially the coils with a core, and the change in electrical properties over time for capacitors. For a certain type of consumer, the improvement of the current waveform depends on the type of filter used, the possibility of improving the power factor (to use electrical energy efficiently), and the role of the source impedance, which is particularly important to improve the efficiency of passive filters. Through the appropriate choice of the passive filter, a decrease in the deforming regime is obtained, with a slight decrease in the active power, and by increasing the power factor, a decrease in the losses of electrical energy from the electrical networks is obtained, with direct implications for the emission of greenhouse gases.

Life cycle assessment of high-power white LEDs for indoor lighting in the context of Hong Kong

The introduction of white light-emitting diodes (LEDs) is one of the key innovations that has revolutionized the lighting industry due to its multiple benefits. Despite their advantages, there is a gap in the environmental impact information of the recently developed high-power LED products within the whole lifecycle, which is a key step to achieve sustainable and green development. This life cycle assessment (LCA) is conducted by considering the cradle-to-grave system boundary. The functional units considered are a LED and compact fluorescent lamp (CFL) of 40 million lumen-hours (lm-h) used for indoor applications over an operating time of 20 000 h. In this study, the LCA was carried out using the SimaPro software and built-in ecoinvent database V2.2 with appropriate life cycle inventory data. The analysis results indicate that: (1) the LED-package has a dominant environmental impact followed by the LED driver while the housing and corrugated-board packaging materials showed the least negative effect to the ecosystem during the manufacturing phase. On the contrary, the CFL drivers are dominant followed by the light sources in the case of CFLs. From the lifecycle stages, the usage-phase showed a predominant environmental effect, mainly due to the energy consumption and sources of energy production. (2) A scenario analysis on the sources of electricity production revealed that prospective sources (70% natural gas, 25% nuclear and 5% pumped storage) of energy production lowered the environmental impact compared to the current electricity mix. These proposed electricity generation production sources provide a 61% reduction in the global warming potential in light sources for Hong Kong.

Designing Ionic Ir(III) Cyclometalated Complexes as Photocatalysts for Light Assisted ATRP of MMA. A Combined Experimental and Mechanistic Study.

A new family of ionic Ir(III) cyclometalated complexes with general formula [Ir(CN)2(NN)][Br], was designed and prepared to be assessed as photocalysts for the visible light assisted ATRP polymerization of MMA. To this purpose, our design strategy involved both: i) the decoration of the cyclometalating (CN) and the ancillary (NN) ligands with various electron withdrawing and/or electron donor substituents and, ii) the use of Br- as the counter anion for these cationic Ir(III) species. After an extensive screening in which the [Ir(CN)2(NN)][Br]-type compounds were compared to the model neutral complex fac-[Ir(ppy)3], the "fully" amino-substituted ion pairs abbreviated as [10][Br] and [11][Br], exhibited the best photocatalytic performances under irradiation with CFL lamps. It is worth noting that the outcomes of transient absorption spectroscopy (TAS) experiments combined with theoretical DFT calculations, enlightened the role played by the Ir(III) complexes in the mechanism of the photoATRP process, and suggested the rationalization of the different performances that were highlighted by our Ir(III) catalyst in the visible light assisted photopolymerization of MMA.

The Role of Nanotechnology in Energy-Efficient Lighting: Evaluating Store Building Lighting Using Dialux and MsExcel

The Role of Nanotechnology in Energy-Efficient Lighting: Evaluating Store Building Lighting Using Dialux and MsExcel

Analysis of Losses Associated with Series Resistance (Rs) in Simple-Structured c-Si Solar Cells

The assessment of photovoltaic devices, which convert light energy into electricity, has become significantly more relevant due to the aspiration to reduce pollution on a global scale. In this context, the pursuit of optimizing the efficiency of converting light energy into electrical energy involves exhaustive studies and structural analyses of solar cells, all directed toward achieving this goal. This study introduces a research proposal aimed at analyzing the losses associated with series resistance (Rs). The analysis takes into account each component comprising this resistance, proposing a network of resistances that precisely models each of these elements. The aforementioned research focused on simple-structured crystalline silicon cells. During this investigation, the junction depth (xj) of the n-p materials was varied, with the aim of achieving efficiencies in the range of 12%. However, in the pursuit of this desired efficiency, a significant impact on series resistance was observed when analyzing the I-V curves of the cells obtained in each manufacturing process.

AN ANALYSIS OF DIFFERENCE IN FEMALES AND MALES ATTITUDE TOWARDS ECO-FRIENDLY PRACTICES AT HOME

Background: Eco-friendly behavior, sometimes referred to as green behavior or eco-behavior, is the idea that people, groups, and communities should make decisions and take activities to reduce their environmental effect and advance ecological sustainability. Ecological behavior is essential for maintaining biodiversity, protecting ecosystems, and conserving natural resources. The current study focuses on the environmentally conscious actions that Bhopal city’s men and women take at home. Objective: The objective of the study was to examine the attitude of men and women towards eco friendly habits at home. Methodology: The present research is quantitative, in nature. The study was conducted in the Bhopal city. Convenience sampling was used for the collection of the data. Respondents were asked closed-ended questions on 5-point Likert scale related to their demographic profile and their attitude towards eco friendly practices at home. 270 responses from162 male and 108 were female respondents aged more than 18 years was collected. Descriptive statistics was adopted to get the results of present research. Results: In order of importance male showcased importance for saving water (84%), switch the light off when leaving a room (76.5%), use of energy efficient light bulbs (76.5%) and turn AC off in unoccupied rooms (75.3%) are the top four eco-friendly practices. For female switching the light off when leaving a room (90.7%), saving water (83.3%), turning AC off in unoccupied rooms (81.5%) and turning heat off in unoccupied rooms (79.6%) were the top four eco-friendly practices followed at their homes. Conclusion: Saving water, switching the light off when leaving a room, using of energy efficient light bulbs and turning AC off in unoccupied rooms were the top four eco-friendly practices which are mostly practiced by males at their homes. For female switching the light off when leaving a room, saving water, Turning AC off in unoccupied rooms and Turning heat off in unoccupied rooms were the top four eco-friendly practices.

Influence of the Supply Voltage Variation on the Conducted Emission in the Frequency Range up to 150 kHz Injected into the Power Grid by CFL and LED Lamps—Case Study

In normal operating conditions, the mains voltage level provided by low-voltage distribution networks follows time-varying patterns within permissible limits. The statistical characterisation of disturbances inserted into the power grid by nonlinear electrical devices is useful since operators are able to establish power quality limits and assess the residual capacity of networks for new smart installations, which may include a multitude of power electronic devices. Existing standards related to emission tests recommend using a power supply source in the measurement circuit with a nominal voltage parameter. However, the range of permissible variations of relevant supply voltage parameters may have an impact on conducted emissions. It can also be considered that the symptoms of supply voltage variations may manifest themselves differently depending on the equipment’s architecture and also the range of frequency observation with reference to harmonics and supraharmonics. The purpose of this study is to measure and analyze non-intentional conducted emissions injected into the power grid by lighting devices, methodically, by numbers of studies under different supply voltage conditions within two frequency bands. The emission is evaluated separately in two ranges: up to 2 kHz and 9-150 kHz. Obtained results show that the level of conducted emission introduced into the low voltage network by modern lighting sources like fluorescent and LED lamps varies with the supply voltage level compared to the emission generated in the nominal voltage level condition. Additionally, in the case of a spectrum of higher frequencies, some trends of shifting of the characteristic frequency bands are recorded. The potential of the obtained results is to complement the knowledge of the emission of modern lighting sources, which can be further used for digital models of these devices and to estimate the impact on the grid under real working conditions.

Facile preparation of environmental benign LED white light active humic acid nanolayer coated titanium dioxide photocatalyst for bisphenol A degradation

Natural organic matter is a mixture of microbial decomposition products widely found in surface and groundwater. These organic materials have great potential as carbon-based precursors for chemical synthesis. This work demonstrated the development of a green photocatalyst via a facile adsorption process that combined colloidal titanium dioxide (TiO2) with humic acid. The resulting photocatalyst was visible light active and able to completely degrade 5 mg/L of BPA within 6 h under the irradiation of energy-efficient LED white light. The first-order kinetic rate constant of the reaction was determined to be 1.7 × 10−2 min−1. The enhanced photocatalytic activity was attributed to the decreased band gap energy and effective charge separation that limits the photogenerated electron-hole recombination. The outcome of this research opened an opportunity for the development of sustainable functional materials using natural organic matter.

Satellite Hyperspectral Nighttime Light Observation and Identification with DESIS

The satellite imagery of nighttime lights (NTLs) has been studied to understand human activities, economic development, and more recently, the ecological impact of brighter night skies. The Visible Infrared Imaging Radiometer Suite (VIIRS) Day–Night Band (DNB) offers perhaps the most advanced nighttime imaging capabilities to date, but its large pixel size and single band capture large-scale changes in NTL while missing granular but important details, such as lighting type and brightness. To better understand individual NTL sources in a region, the spectra of nighttime lights captured by the DLR Earth Sensing Imaging Spectrometer (DESIS) were extracted and compared against near-coincident VIIRS DNB imagery. The analysis shows that DESIS’s finer spatial and spectral resolutions can detect individual NTL locations and types beyond what is possible with the DNB. Extracted night light spectra, validated against ground truth measurements, demonstrate DESIS’s ability to accurately detect and identify narrow-band atomic emission lines that characterize the spectra of high-intensity discharge (HID) light sources and the broader spectral features associated with different light-emitting diode (LED) lights. These results suggest the possible application of using hyperspectral data from moderate-resolution sensors to identify lamp construction details, such as illumination source type and light quality in low-light contexts. NTL data from DESIS and other hyperspectral sensors may improve the scientific understanding of light pollution, lighting quality, and energy efficiency by identifying, evaluating, and mapping individual and small groups of light sources.

Enhanced efficiency and thermal performance of multistage gradient doping Ce:YAG transparent ceramics for laser lighting

The key to realizing the applications of ceramic based laser lighting devices depends on the heat management capability of color converters. In order to sufficiently absorb the blue light and smoothen the temperature gradient of luminescent ceramics, multistage gradient doping Ce3+:Y3Al5O12 (Ce:YAG) transparent ceramics (TCs) with five different concentrations were designed, including 0.01 at%, 0.05 at%, 0.1 at%, 0.2 at% and 0.4 at% Ce. The composite green bodies were prepared by aqueous tape casting and multistage gradient doping Ce:YAG TCs, with concentrations from low to high, were fabricated by vacuum sintering. The in-line transmission values at 800 nm of composite structure Ce:YAG TCs could reach 80.3%. Under 21.13 W/mm2 blue laser excitation, the gradient doping Ce:YAG TC (1.32 mm) realized a high luminous efficacy of 280.3 lm/W, which was 15.8% higher than that of 0.15 at% Ce:YAG TC (240.27 lm/W). Finally, during lighting process, the input-output temperature differences (Tin-Tout) between excitation surface and light-exit surface of 0.15 at% Ce:YAG TC was 5 ℃, while that in gradient doping TC reduced by 50% (2.5 ℃). The results indicate that the multistage gradient doping Ce:YAG TCs will be an interesting color converter for high-power and energy-saving laser-driven lighting.

Coping with darkness: residents’ experience of reduced outdoor lighting in neighbourhoods

Despite ongoing replacement of old lighting installations with new energy-efficient light emitting diodes, the energy crisis has led to the implementation of strategies for reducing energy use for public outdoor lighting in neighbourhood environments. This would save money and reduce light pollution; however, the situations should be evaluated from the residents’ perspective. This paper presents a pilot study, which aimed to explore how residents experience and respond to reduced outdoor lighting in their neighbourhoods during dark hours, by applying the adapted Human-Environment Interaction model to understand the relation between outdoor lighting quality, neighbourhood quality and local independent mobility from the residents’ perspective. The pilot study was based on a short questionnaire (N =76, 29 males, 47 females, Mage = 66.66 years) and telephone or online interviews (N = 13, 5 males, 8 females, Mage = 68.08 years) with the residents living in the neighbourhood areas, in Southern Sweden, where strategies were employed for reducing the use of public outdoor lighting. Data were collected between February and March 2023. Overall, the results affirmed the important role of outdoor lighting quality in residents’ experience of neighbourhood environments and local independent mobility (i.e. the ability of residents to walk or move around on their own in their neighbourhood area), whereas the effect of reduced outdoor lighting was rather insignificant. The interviews further showed different experiences of the reduced outdoor lighting and how the residents coped with the lighting conditions by using solutions (i.e. headlamps, flashlights, bike lamps and reflectors), and that high-level perceived safety from crime in the neighbourhoods was found to play an important role in local independent mobility during dark hours. The adapted conceptual model allowed for the evaluation of outdoor lighting conditions considering both internal and external factors from the residents’ perspective, and could provide a basis for discussion about potential changes in public outdoor lighting.

The Physiological Basis of Alfalfa Plant Height Establishment.

Plant height plays an important role in crop yield, product quality, and cultivation management. However, the physiological mechanisms that regulate the establishment of plant height in alfalfa plants remain unclear. Herein, we measured plant height traits, leaf characteristics, photosynthetic physiology, cell wall composition, and endogenous hormone contents of tall- and short-stalked alfalfa materials at different reproductive periods. We analyzed the physiology responsible for differences in plant height. The results demonstrated that the number of internodes in tall- and short-stalked alfalfa materials tended to converge with the advancement of the fertility period. Meanwhile, the average internode length (IL) of tall-stalked materials was significantly higher than that of short-stalked materials at different fertility periods, with internode length identified as the main trait determining the differences in alfalfa plant height. Leaf characteristics, which are closely related to photosynthetic capacity, are crucial energy sources supporting the expression of plant height traits, and we found that an increase in the number of leaves contributed to a proportional increase in plant height. Additionally, a significant positive correlation was observed between plant height and leaf dry weight per plant during the branching and early flowering stages of alfalfa. The leaves of alfalfa affect plant height through photosynthesis, with the budding stage identified as the key period for efficient light energy utilization. Plant height at the budding stage showed a significant positive correlation with soluble sugar (SS) content and a significant negative correlation with intercellular CO2 concentration. Moreover, we found that alfalfa plant height was significantly correlated with the contents of indole-3-acetic acid in stem tips (SIAA), gibberellin A3 in leaves (LGA3), zeatin in stem tips (SZT), and abscisic acid in leaves (LABA). Further investigation revealed that SS, SIAA, and LGA3 contents were important physiological indicators affecting alfalfa plant height. This study provides a theoretical basis for understanding the formation of alfalfa plant height traits and for genetic improvement studies.