Light Intensity Pattern Research Articles

Optogenetic Fine-Tuning of Sus scrofa Basic Fibroblast Growth Factor Expression in Escherichia coli

Basic fibroblast growth factor (bFGF) is a crucial protein with diverse applications in biotechnology and medicine. This study aims to investigate the use of EL222-based optogenetic control systems to fine-tune the expression of porcine (Sus scrofa) bFGF in Escherichia coli. The bioactivity and the productivity of blue light-induced bFGF were demonstrated to be comparable to those achieved using a conventional T7-expression system. Secondly, through systematic optimization of regulatory elements, optimal expression of bFGF was achieved using a medium-strength promoter for EL222 expression, a strong RBS upstream of the bFGF gene, and an optimized C120 configuration within the blue light-inducible promoter. Moreover, various parameters of blue light illumination during fermentation were investigated, including initial cell density, light intensity, illumination duration, and pulsed illumination patterns. The results identified optimal conditions for maximizing bFGF yield in E. coli, specifically an initial OD600 of 0.6, 800 lux blue light intensity, and 8 h total illumination in a 2 h on/off pattern. Overall, this successful implementation of optogenetically controlled bFGF expression in E. coli serves as a proof-of-concept for light-responsive systems in industrial biotechnology, highlighting the potential of optogenetic control for biologically active protein production.

Vertical farming goes dynamic: optimizing resource use efficiency, product quality, and energy costs

Vertical farming is considered to be a key enabler for transforming agrifood systems, especially in or nearby urbanized areas. Vertical farming systems (VFS) are advanced indoor cropping systems that allow for highly intensified and standardized plant production. The close control of environmental parameters makes crop production stable and repeatable, ensuring year-round uniform product quality and quantity irrespective of location. However, due to continuous changes in plant physiology and development, as well as frequent changes in electricity prices, the optimum conditions for crop production and its associated costs can change within days or even minutes. This makes it beneficial to dynamically adjust setpoints for light (intensity, spectrum, pattern, and daylength), CO2, temperature, humidity, air flow, and water and nutrient availability. In this review, we highlight the beneficial effects that dynamic growth conditions can have on key plant processes, including improvements in photosynthetic gas exchange, transpiration, organ growth, development, light interception, flowering, and product quality. Our novel findings based on modeling and experimentation demonstrate that a dynamic daily light intensity pattern that responds to frequent changes in electricity prices can save costs without reducing biomass. Further, we argue that a smart, dynamic VFS climate management requires feedback mechanisms: several mobile and immobile sensors could work in combination to continuously monitor the crop, generating data that feeds into crop growth models, which, in turn, generate climate setpoints. In addition, we posit that breeding for the VFS environment is at a very early stage and highlight traits for breeding for this specialized environment. We envision a continuous feedback loop between dynamic crop management, crop monitoring, and trait selection for genotypes that are specialized for these conditions.

Shining light on diurnal variation of non‐photochemical quenching: Impact of gradual light intensity patterns on short‐term NPQ over a day

AbstractMaximal sunlight intensity varies diurnally due to the earth's rotation. Whether this slow diurnal pattern influences the photoprotective capacity of plants throughout the day is unknown. We investigated diurnal variation in NPQ, along with NPQ capacity, induction, and relaxation kinetics after transitions to high light, in tomato plants grown under diurnal parabolic (DP) or constant (DC) light intensity regimes. DP light intensity peaked at midday (470 μmol m‐2 s‐1) while DC stayed constant at 300 μmol m‐2 s‐1 at a similar 12‐hour photoperiod and daily light integral. NPQs were higher in the morning and afternoon at lower light intensities in DP compared to DC, except shortly after dawn. NPQ capacity increased from midday to the end of the day, with higher values in DP than in DC. At high light ΦPSII did not vary throughout the day, while ΦNPQ varied consistently with NPQ capacity. Reduced ΦNO suggested less susceptibility to photodamage at the end of the day. NPQ induction was faster at midday than at the start of the day and in DC than in DP, with overshoot occurring in the morning and midday but not at the end of the day. NPQ relaxation was faster in DP than in DC. The xanthophyll de‐epoxidation state and reduced demand for photochemistry could not explain the observed diurnal variations in photoprotective capacity. In conclusion, this study showed diurnal variation in regulated photoprotective capacity at moderate growth light intensity, which was not explained by instantaneous light intensity or increasing photoinhibition over the day and was influenced by acclimation to constant light intensity.

Group Control of Photo-Responsive Colloidal Motors with a Structured Light Field

Using structured light to drive colloidal motors, due to its advantages of remote manipulation, energy tunability, programmability, and the controllability of spatiotemporal distribution, has been attracting much attention in the fields of targeted drug delivery, environmental control, chemical agent detection, and smart device design. Here, we focus on studying the group control of colloidal motors made from a photo-responsive organic polymer molecule NO-COP (N,O-Covalent organic polymer). These colloidal motors mainly respond to light intensity patterns. Considering its merits of fast refreshing speed, good programmability, and high-power threshold, we chose a digital micromirror device (DMD) to modulate the structured light field shining on the sample. It was found that under ultraviolet or green light modulation, such colloidal motors exhibit various group behaviors including group spreading, group patterning, and group migration. A qualitative interpretation is also provided for these observations.

Future Scenarios of Urban Nighttime Lights: A Method for Global Cities and Its Application to Urban Expansion and Carbon Emission Estimation

As of 2018, approximately 55% of the world’s population resides in cities, and it is projected that this proportion will reach 68% by 2050. Population growth in urban areas leads to various impacts on society and the environment. In this study, we have developed a method for generating future scenarios of nighttime lights. What makes this method unique is its ability to (1) generate future gridded nighttime light intensity scenarios for cities, (2) generate future scenarios that preserve the distribution pattern of nighttime light intensity, and (3) generate scenarios that reflect urban policies. By applying this developed method, we have estimated nighttime light data for 555 cities worldwide and predicted future urban expansion and changes in carbon emissions for each SSP scenario. Consequently, both urban areas and carbon emissions are estimated to increase for the entire set of target cities, with patterns varying among cities and scenarios. This study contributes to the advancement of urban scenario research, including the estimation of future urban area expansion and carbon emissions.

Illumination Effects on Bacteriorhodopsin Accumulation in Archaeon Halobacterium Halobium

Highlights Effects of varying illumination conditions, including light intensity, light color, and illumination pattern on archaeon Halobacterium halobium growth and bacteriorhodopsin (BR) accumulation were first evaluated. LED green light was much more energy-efficient than the red and blue lights in this research. If energy consumption was not a concern, LED blue and red lights (or their combinations) were more effective for cell growth and BR accumulation, respectively, with a similar light intensity. Abstract. This study was to understand the effect of LED light intensity, color, and illumination pattern on the growth of and bacteriorhodopsin (BR) accumulation in archaeon Halobacterium halobium. Experimental results showed that archaeon growth and BR content increased with increasing white light intensity. Green and white LED lights were found to be the most effective for archaeon growth and BR accumulation; here, effectiveness is defined based on photons shined on the bioreactor. The 12-h light/12-h dark cycle illumination pattern resulted in longer lag phase but achieved higher final cell growth and BR accumulation than continuous white light or an instant flash of light/dark illumination. The fade pattern that had smooth transitioning among green, blue, and red lights was better than the jump pattern without transitioning. The highest cell dry weight and BR content of H. halobium were 1.84 g l-1 and 11.76 mg l-1, respectively, under 29.85 µmol/m2s LED white light illumination. The green LED light of 1.39 µmol/m2s had the highest energy-specific conversion effectiveness and saved energy consumption by 84 and 87% per cell biomass and BR dry weight, respectively, compared to the worst case of LED white light of 29.85 µmol/m2s. Keywords: Archaeon, Bacteriorhodopsin, Halobacterium halobium, Illumination pattern, LED light, Light color.

A spatial and temporal signal fusion based intelligent event recognition method for buried fiber distributed sensing system

Due to the characteristics of high sensitivity, fast response speed and multi-point monitoring, Phase-sensitive optical time-domain reflectometry (Φ-OTDR) has attracted attention in the field of perimeter security. However, the intrusion signals are susceptible to interference by ambient signals and difficult to be recognized. In the field of the vibration event recognition of Φ-OTDR system, the deep-learning based methods achieve great recognition ability. However, the previous works are mostly built on single signal source like temporal signal and may not completely adapt to different environment. In this work, a novel phenomenon is reported that a specific variation pattern of light intensity, which is related to the type of vibration source, is hided in the backscattering traces in spatial domain. Inspired by this, a lightweight model and data composition method is proposed to fuse spatial information with temporal correlation information based on end-to-end CNN-LSTM combined model and bicubic scaling. The experiment is conducted on a portable computer (a Nvidia GPU RTX 2080 with 2944 compute unified device architecture cores) with 8 event types and shows that this method can achieve 95.56% validation accuracy through less than 6 min training. Compared with previous method trained by single image structure signal, this lightweight work can achieve higher validation accuracy faster.

Adaptive museum lighting using CNN-based image segmentation

Modern smart lighting systems have the potential to improve lighting conditions by employing adaptive dimming. However, the light intensity pattern of the individual luminaires is often not optimally matching with the region(s) of interest. By using adaptive lighting fixtures with a tunable radiation pattern, much more targeted illumination can be enabled. The already demonstrated adaptive lighting fixtures are typically quite bulky, and require user input to optimize the emitted light. In this paper, a compact lighting fixture is proposed that consists of a high-power LED, a sequence of lenses, an adjustable mirror and tunable diffuser, to achieve an adaptive lighting functionality. This adaptive luminaire is integrated with an embedded system and camera, to realize autonomous beam adjustment based on computer vision in a museum setting. The embedded system performs semantic segmentation to detect painting masks, and adapts the light beam direction and spot size to the detected painting frame via a feedback loop. The system can be considered as a first demonstration of the integration between state-of-the-art computer vision and adaptive light fixtures for indoor lighting.

LIPAuth : Hand-dependent Light Intensity Patterns for Resilient User Authentication

Authentication mechanisms deployed on access control systems undertake the responsibility of judging user identity to prevent unauthorized individuals from illegally approaching. In this article, we propose LIPAuth leveraging hand-dependent L ight I ntensity P attern to Auth enticate users. To be specific, lights released by a screen, are blocked and reflected by one hand above it; in this propagation process, hands exhibit user-specific ability in driving light absorption and attenuation due to owning unique structures, thereby outputting discriminative intensity patterns representing user identity. To implement LIPAuth , we first study the impact of screen contents on light intensity patterns, also explore the possibility of embedding hand structure biometrics into these patterns. We then design a customized dynamic stimulus-response mechanism for LIPAuth and make it resilient to the risks of potential registration profile leakage. Subsequently, we construct a joint pipeline consisting of signal processing and a learning-based generative adversarial network to overcome interference from variable user behaviors. More importantly, LIPAuth just utilizes common sensors to capture light signals, hence achieving low cost. We finally conduct extensive experiments in three scenarios to evaluate the authentication performance of LIPAuth prototype.

Long-exposure NuSTAR constraints on decaying dark matter in the Galactic halo

We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In the first, we utilize the known intensity pattern of unfocused stray light across the detector planes -- the dominant source of photons from diffuse sources -- to separate astrophysical emission from internal instrument backgrounds using ${\sim}$7-Ms/detector deep blank-sky exposures. In the second, we present an updated parametric model of the full NuSTAR instrument background, allowing us to leverage the statistical power of an independent ${\sim}$20-Ms/detector stacked exposures spread across the sky. Finding no evidence of anomalous x-ray lines using either method, we set limits on the active-sterile mixing angle $\sin^2(2\theta)$ for sterile-neutrino masses 6--40 keV. The first key result is that we strongly disfavor a ${\sim}$7-keV sterile neutrino decaying into a 3.5-keV photon. The second is that we derive leading limits on sterile neutrinos with masses ${\sim}$15--18 keV and ${\sim}$25--40 keV, reaching or extending below the Big Bang Nucleosynthesis limit. In combination with previous results, the parameter space for the Neutrino Minimal Standard Model ($\nu$MSM) is now nearly closed.

Mapping complex profiles of light intensity with interferometric lithography.

Solving Maxwell's equations numerically to map electromagnetic fields in the vicinity of nanostructured metal surfaces can be a daunting task when studying non-periodic, extended patterns. However, for many nanophotonic applications such as sensing or photovoltaics it is often important to have an accurate description of the actual, experimental spatial field distributions near device surfaces. In this article, we show that the complex light intensity patterns formed by closely-spaced multiple apertures in a metal film can be faithfully mapped with sub-wavelength resolution, from near-field to far-field, in the form of a 3D solid replica of isointensity surfaces. The permittivity of the metal film plays a role in shaping of the isointensity surfaces, over the entire examined spatial range, which is captured by simulations and confirmed experimentally.

Dynamic threats of nighttime light-represented human activities to giant pandas and their habitat

Human activities are one of the main factors threatening the long-term survival of wild giant pandas. Long-term and large-scale human activities can be quickly assessed by night light remote sensing data, which has been more and more widely used. In this paper, we analyzed the spatial patterns of nighttime light intensity and their dynamic changes from 2000 to 2020 in the entire giant panda distribution area using long-term nighttime light remote sensing data, and evaluated the dynamic threats of nighttime light-represented human activities to giant panda populations by proximity of light source and its intensity. We also assessed the relationships between the nighttime light dynamics and the trends of habitat fragmentation. Results showed that the intensity and range of the nighttime light around panda habitat had increased significantly from 2000 to 2020. The nighttime light intensity inside the natural reserves is significantly lower than outside, and it becomes more obvious over time. The intensity and range of nighttime light inside the natural reserves first increased and then decreased during the two decades, indicating that the protection inside the natural reserves effectively reversed the rapid increase in human activities in the previous decade. From 2000 to 2020, nighttime light sources became closer to local panda populations. In particular, they approached the pandas in the first decade, and stayed away in the second decade. This is mainly reflected in the weakened threats of nighttime light-represented human activities on the core large populations of the Qinling, Minshan and Qionglai Mountains from 2010 to 2020, but the threats on the peripheral populations continued to strengthen, where nighttime light became not only closer but also more intensified. The increase in nighttime light intensity and range were also significantly positively correlated with the increase in habitat fragmentation, especially during 2000–2010. Our study reveals the dynamic changes of nighttime light-represented human activities’ threats to wild giant panda and its habitat, gives advices for effectively protecting giant pandas and their habitats from human activities, and has implications for the assessment of human activities’ threats to other species in the world.

Manufacturing Functional Polymer Surfaces by Direct Laser Interference Patterning (DLIP): A Polymer Science View

Direct laser interference patterning (DLIP) involves the formation of patterns of light intensity using coherent laser light beams that interfere between them. Light on the ultraviolet (<350 nm) and NIR (800–2000 nm) is absorbed in chromophores present in the polymer structure or in loaded absorbing species (dyes, polymers, nanoparticles). The absorbed light induces photothermal/photochemical processes, which alter permanently the topography of the polymer surface. The success of DLIP at different wavelengths is discussed in relation to the optical/thermal properties of the polymers and previous data on laser ablation of polymers. The size of the pattern is related directly to the wavelength of the light and inversely to the sine of the angle between beams and the refractive index of the external medium. In that way, nanometric structures (<100 nm) could be produced. Since the patterning occurs in a single short pulse (<10 ns), large surfaces can be modified. Both bacterial biofilm inhibition and human cell differentiation/orientation have been achieved. Large improvements in technological devices (e.g., thin film solar cells) using DLIP structured surfaces have also been demonstrated. Prospective application of DLIP to common polymers (e.g., Teflon®) and complex polymeric systems (e.g., layer-by-layer multilayers) is discussed on the basis of reported polymer data.

Propagation characteristics of cosine-Gaussian cross-phase beams in strongly nonlocal nonlinear media

In this paper, the propagation expression of cosine-Gaussian cross-phase beams (CGCPBs) is derived based on the nonlocal nonlinear Schrödinger equation and the propagation characteristics of CGCPBs in strongly nonlocal nonlinear media (SNNM) are researched. It is worth noting that the mode of CGCPBs can be controlled by modifying the parameters of cosine term and cross phase term. CGCPBs can form generalized high-order breathers, which signifies that the multi-peak light intensity pattern and the beam width evolve periodically during the transmission process. Apart from that, the impact of the parameters on the light intensity mode, the phase and the beam width is discussed by changing the parameters in the initial incident transmission expression. The research content of this paper provides reference value for controlling beams.

Propagation properties of controllable anomalous hollow beams in strongly nonlocal nonlinear media

The evolution properties of controllable anomalous hollow beams (CAHBs) in strongly nonlocal nonlinear medium are studied theoretically and numerically. The CAHB has a circular light intensity distribution, but there is a solid light intensity peak in the center. By changing initial parameters, the central and peripheral light intensities can be adjusted, so the CAHB can represent many different types of beams. The CAHBs in strongly nonlocal media shows a very rich variety of propagation characteristics. The transmission evolution properties of CAHBs, such as the light intensity distribution, the beam width and the on-axis light intensity, are mainly studied. The results show that by choosing appropriate initial parameters, the light intensity pattern of CAHBs can remain unchanged and form solitons, but also change periodically. The beam width of CAHBs can be widened or compressed in two transverse directions at the same time, or widened in one direction and compressed in the other direction. Some typical transmission characteristics are illustrated by numerical simulation, and the role of various parameters in transmission evolution is analyzed.

Transient optically induced grating and underlying transport process in bent-core nematics

In this paper, we have applied a holographic time-of-flight technique with a nanosecond laser pulse to perform time-resolved measurements of optically induced gratings in bent-core nematics formed by a new kind of liquid crystal (LC). The effects of the electric field, laser pulse energy, temperature, and light intensity pattern on the photocharge transport process were investigated systematically. The results indicate that some peculiar features, such as high photosensitivity, relatively large mobility, and negative conductivity anisotropy, were present in the studied soft-matter system. Furthermore, a coupling between the optically induced grating and electrically induced convection was observed, which revealed a competitive state between them via the transport process. Thus, a better understanding of the carrier transport process involving photosensitivity and response time will help to tailor LC devices toward novel optical applications.

A new contour balancing rearrangement technique to enhance the solar PV array power under a realistic partial shading condition

Under partial shading conditions, the solar photovoltaic (PV) array receives an irregular pattern of solar light intensity which results in the creation of multiple peaks in the power vs voltage (P-V) and current vs voltage (I-V) plot and ultimately leads to hot spots creation and reduced power generation. Therefore, in this paper, redistribution of the shadow effect is assessed using a newly proposed reconfiguration method for the PV array called Contour Balancing Rearrangement (CBR) method. The proposed CBR method is based on the “Smash n′ Throw” approach which is applied to reconfigure the total-cross-tied (TCT) topology of the PV array that redistributes the shading pattern in such a way that the average irradiance of each row is almost the same. Further, a novel pragmatic dynamic cloud model is formulated to realize the partial shading condition as in realistic form at a particular location of the earth’s surface. For a more realistic analysis, the movement and acceleration of moving clouds are taken into account along with the coordinates of the place of interest for more accurate values of solar irradiation. Furthermore, different comparative studies are also carried out among the proposed and existing methods of various PV array reconfiguration methods to show the efficacy.

UFLPlus: An Underwater Fish Lamp Technology as an Innovation of Fish-Luring Aids on Boat Lift Net

Highlight ResearchDipped lamp technology with CCTV (UFLPlus) to catch fish was designed in such a way that the placement of components contained was integrated, water-proof, and having a good light distribution.The existence of a CCTV in new innovated UFLPlus that can record events in the water and greatly assist fishing activities of fishermen on passive fishing gear such as boat charts.UFLPlus worked well to increase the number of hauling every night of fishing (from 20-30 kg to 50-60 kg per hauling).AbstractThe usage of underwater immersion lights outfitted with CCTV is a technological innovation that is expected to solve the inadequacies of the acoustic work system while also improving the existing underwater immersion light work system. Underwater Fish Lamp Plus (UFLPlus) technology can attract attention and directly monitor the condition of fish in the sea from the boat. The purpose of this study was to understand how the UFLPlus was designed and constructed; to test its performance using lamplight, waterproof, and immersion tests; to learn how the light distribution pattern is formed; and to learn the state of the catch. The study was separated into two phases: the design and fabrication of UFLPlus, and numerous laboratory-scale experiments and outdoor trials with boat lift net fishing gear. The results reveal that UFLPlus performed effectively in the field after all of its physical components were tested in the laboratory, and that the values of light intensity and light distribution patterns are still in accordance with the level of adaptation to light reception on the fish retina. During the trial catch, 62 kg of anchovy (Stolephorus sp.), 27 kg of ponyfishes (Leiognathus sp.), 32.5 kg of fringe-scale sardinella (Sardinella fimbriata), and 17.5 kg of yellow-stripe scad (Selaroides leptolepis) were caught. UFLPlus was capable of functioning as an underwater immersion lamp that attracts fish attention and directly monitors the arrival of fish in the water in the fishing area.

Periodic propagation of complex-valued hyperbolic-cosine-Gaussian solitons and breathers with complicated light field structure in strongly nonlocal nonlinear media

In this study, the propagation characteristics of complex-valued hyperbolic-cosine-Gaussian (CVHCG) beams were studied based on the nonlocal nonlinear Schrödinger equation in strongly nonlocal nonlinear media (SNNM). The CVHCG beams exhibited some unique propagation characteristics. By adjusting the complex-valued parameters, CVHCG beams can propagate with different forms in SNNM, including Gaussian-like, nearly flat-topped, multi-peak, and four-peak forms. CVHCG beams can form shape-invariant solitons and breathers under certain incident parameters. In addition, CVHCG beams can also form generalized shape-variant high-order spatial solitons and breathers. In general, the beam width and light intensity pattern of the CVHCG beams always change periodically. A complete theoretical model was constructed, and the expressions for the propagation, light intensity, and second-order moment beam width were obtained analytically. Some typical propagation characteristics were demonstrated via numerical simulations. The results of this study can be extended to investigate other complex-valued beams.

Optimal control as a tool to investigate the profitability of a Chinese plant factory - lettuce production system

Although optimal control has been used extensively for greenhouse climate management, its application to plant factories is still in its infancy. In this paper, profitability of growing lettuce in a Chinese plant factory is investigated by means of optimal control computations. To that end, first, a lettuce growth model is adapted to fit a plant factory environment. Next, this model is calibrated and validated using nine sets of experimental data with different LED light intensities. Using the calibrated and validated model, optimal control computations are used to produce a 3D plot revealing the influence of the electricity and lettuce price on maximum profit. Lettuce's physiological demand for dark periods during artificial lighting is incorporated by fixing this dark period to eight hours a day. Therefore, the optimal LED light intensity pattern obtained from the optimal control computations could be used in the actual production process. Maximum profit can reach 264.88 RMB m −2 assuming a Chinese plant factory fresh lettuce price of 34.5 RMB kg −1 . When lettuce must be sold at 5.01 RMB kg −1 , which represents the price for an open field product, profit always comes out negative. Besides, LED lighting is not advised when the electricity price is greater than 0.84 RMB kWh −1 under these circumstances. Profit is only positive when the lettuce price is over 20 RMB kg −1 . • LED light intensity in a plant factory is optimised to compute profitability. • Dark periods for proper crop growth are implemented through a switching function. • The dynamic lettuce growth model was calibrated on 9 sets of experimental data. • Maximum profit is positive when the fresh lettuce price is over 20 RMB kg −1 . • The maximum profit is 264.88 RMB m −2 in the case of a Chinese plant factory.