Influence Of Light Conditions Research Articles

Lobelia Lakes' Vegetation and Its Photosynthesis Pathways Concerning Water Parameters and the Stable Carbon Isotopic Composition of Plants' Organic Matter.

Most of the aquatic vegetation produces organic substances via the C3 photosynthetic pathway (mosses, isoetids-Lobelia dortmanna L., Luronium natans (L.) Raf., and vascular plants) or Crassulacean acid metabolism (CAM, e.g., Littorella uniflora (L.) Asch. and Isoëtes lacustris L.) or by their ability to use HCO3- via carbon concentration mechanisms (CCMs-some elodeids and charophytes). Differentiating these predominant photosynthetic pathways in aquatic vegetation based on their organic matter (OM) carbon stable isotopes (δ13CORG) is a complex task, in contrast to terrestrial plants. This study investigates the OM deposition, characterized by δ13CORG values in 10 macrophyte species with different photosynthetic pathways (C3, CAM, and CCM) collected from 14 softwater Lobelia lakes in northern Poland. The higher δ13CORG values distinguish the CCM group, indicating their use of 13C-enriched HCO3¯ in photosynthesis. CAM species show slightly higher δ13CORG values than C3, particularly in lower pH lakes. Principal component analysis of isotopic and environmental data did not yield clear distinctions by the groups, but still, they significantly differ in light of analyzed parameters and isotopic signals (PRMANOVA = 5.08, p < 0.01; K-W H = 27.01, p < 0.001). The first two PCA dimensions showed that the water pH and Ca2+ concentration positively influenced δ13C values. The influence of light conditions on δ13CORG values revealed by third PCA components seems to also be important. In summary, northern Polish Lobelia lakes serve as a key differentiation point between vegetation employing CCMs and those relying on C3/CAM photosynthesis without HCO3- utilization, providing insights into transitions in plant communities within these ecosystems.

Modification in ICU Design May Affect Delirium and Circadian Melatonin: A Proof of Concept Pilot Study.

Nonpharmacologic delirium management is recommended by current guidelines, but studies on the impact of ICU design are still limited. The study's primary purpose was to determine if a multicomponent change in room design prevents ICU delirium. Second, the influence of lighting conditions on serum melatonin was assessed. Prospective observational cohort pilot study. The new design concept was established in two two-bed ICU rooms of a university hospital. Besides modifications aimed at stress relief, it includes a new dynamic lighting system. Seventy-four adult critically ill patients on mechanical ventilation with an expected ICU length of stay of at least 48 hours, treated in modified or standard rooms. None. The clinical examination included a prospective assessment for depth of sedation, delirium, and pain every 8 hours using validated scores. Blood samples for serum melatonin profiles were collected every 4 hours for a maximum of three 24-hour periods. Seventy-four patients were included in the analysis. Seventy-six percent ( n = 28) of patients in the standard rooms developed delirium compared with 46% of patients ( n = 17) in the modified rooms ( p = 0.017). Patients in standard rooms (vs. modified rooms) had a 2.3-fold higher delirium severity (odds ratio = 2.292; 95% CI, 1.582-3.321; p < 0.0001). Light intensity, calculated using the measure of circadian effective irradiance, significantly influenced the course of serum melatonin ( p < 0.0001). Significant interactions ( p < 0.001) revealed that differences in serum melatonin between patients in standard and modified rooms were not the same over time but varied in specific periods of time. Modifications in ICU room design may influence the incidence and severity of delirium. Dedicated light therapy could potentially influence delirium outcomes by modulating circadian melatonin levels.

Influence of light conditions on the production of chrysolaminarin using Phaeodactylum tricornutum in artificially illuminated photobioreactors.

The light conditions are of utmost importance in any microalgae production process especially involving artificial illumination. This also applies to a chrysolaminarin (soluble 1,3-β-glucan) production process using the diatom Phaeodactylum tricornutum. Here we examine the influence of the amount of light per gram biomass (specific light availability) and the influence of two different biomass densities (at the same amount of light per gram biomass) on the accumulation of the storage product chrysolaminarin during nitrogen depletion in artificially illuminated flat-panel airlift photobioreactors. Besides chrysolaminarin, other compounds (fucoxanthin, fatty acids used for energy storage [C16 fatty acids], and eicosapentaenoic acid) are regarded as well. Our results show that the time course of C-allocation between chrysolaminarin and fatty acids, serving as storage compounds, is influenced by specific light availability and cell concentration. Furthermore, our findings demonstrate that with increasing specific light availability, the maximal chrysolaminarin content increases. However, this effect is limited. Beyond a certain specific light availability (here: 5 µmolphotons gDW -1 s-1 ) the maximal chrysolaminarin content no longer increases, but the rate of increase becomes faster. Furthermore, the conversion of light to chrysolaminarin is best at the beginning of nitrogen depletion. Additionally, our results show that a high biomass concentration has a negative effect on the maximal chrysolaminarin content, most likely due to the occurring self-shading effects.

Saliency prediction in 360° architectural scenes: Performance and impact of daylight variations

Saliency models are image-based prediction models that estimate human visual attention. Such models, when applied to architectural spaces, could pave the way for design decisions where visual attention is taken into account. In this study, we tested the performance of eleven commonly used saliency models that combine traditional and deep learning methods on 126 rendered interior scenes with associated head tracking data. The data was extracted from three experiments conducted in virtual reality between 2016 and 2018. Two of these datasets pertain to the perceptual effects of daylight and include variations of daylighting conditions for a limited set of interior spaces, thereby allowing to test the influence of light conditions on human head movement. Ground truth maps were extracted from the collected head tracking logs, and the prediction accuracy of the models was tested via the correlation coefficient between ground truth and prediction maps. To address the possible inflation of results due to the equator bias, we conducted complementary analyses by restricting the area of investigation to the equatorial image regions. Although limited to immersive virtual environments, the promising performance of some traditional models such as GBVS360eq and BMS360eq for colored and textured architectural rendered spaces offers us the prospect of their possible integration into design tools. We also observed a strong correlation in head movements for the same space lit by different types of sky, a finding whose generalization requires further investigations based on datasets more specifically developed to address this question.

Understory junipers, and light environment effects on biomass, chemical composition, and nutrient contents of black pine seedlings

In forest environments, the establishment, survival, and recruitment of seedlings of desired species can often be influenced by biotic interactions between the competing understory shrubs and the seedlings, as well as by the understory light environment. Previous studies regarding competing effects were mostly focused on the survival and growth of seedlings, but it is still largely unclear how competition with shrubs impacts the biomass of the seedlings and physiological traits connected to photosynthesis and nitrogen metabolism in various forest ecosystems. Moreover, there is limited knowledge on the influence of light conditions on the biomass of understory seedlings is limited for different species. The main objectives of this study were to examine the effects of understory junipers and light conditions on the above and belowground biomass of black pine seedlings (Pinus nigra Arnold). This study also examined the changes in chemical composition and plant nutrient contents in the organs of black pine seedlings (i.e., root, stem, and needle) with the presence of junipers in the understory. Seedling biomass was significantly affected by understory light conditions, while the presence of junipers negatively affected the root-biomass of black pine seedlings. Moreover, understory junipers influenced some photosynthetic pigments in black pine seedlings.

Response Catharanthus roseus to Plant Growth Regulators in vitro

This experiment was conducted in the tissue culture laboratory for postgraduate studies of the Department of Life Sciences in the College of Science, Al-Qadisiyah University to obtain a study of the response of Catharanthus roseus to the external growth stimuli, which include plant growth regulators, auxins (IAA, NAA, IBA) and cytokines (Kin, BA), under the influence of light conditions. On the characteristics of explants and callus growth that incubated in the growth room, 16 hours of light and 8 hours of darkness or continuous darkness. A high rate dilution of sterilization was prepared for plant growth, and all experiments showed that the medium (MS) at a concentration of 4.44 gm with sucrose at a concentration of 30 gm and the agar at a concentration of 7 gm with growth regulators that resulted in a group of growths, which was represented by the vegetative growth of the plant as a result of its development on a medium in which the best combination was (NAA and Kin) At a concentration of 1 mg each of auxin with cytokines. Where the highest levels of interaction between auxin and cytokinin in illumination for the growing apex were (96.6%) and for single nodules it was (83.3%). As for the incubation period in the continuous darkness, the highest rates of bilateral overlap for the developing peaks and for the single nodes were (85.7%) and (42.8%), respectively.

Effect of Light Conditions on Polyphenol Production in Transformed Shoot Culture of Salvia bulleyana Diels.

Various strategies have been used to increase the efficiency of secondary metabolite production in Salvia plants. This report is the first to examine the spontaneous development of Salvia bulleyana shoots transformed by Agrobacterium rhizogenes on hairy roots and the influence of light conditions on the phytochemical profile of this shoot culture. The transformed shoots were cultivated on solid MS medium with 0.1 mg/L of IAA (indole-3-acetic acid) and 1 mg/L of m-Top (meta-topolin), and their transgenic characteristic was confirmed by PCR-based detection of the rolB and rolC genes in the target plant genome. This study assessed the phytochemical, morphological, and physiological responses of the shoot culture under stimulation by light-emitting diodes (LEDs) with different wavelengths (white, WL; blue, B; red, RL; and red/blue, ML) and under fluorescent lamps (FL, control). Eleven polyphenols identified as phenolic acids and their derivatives were detected via ultrahigh-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (UPLC-DAD/ESI-MS) in the plant material, and their content was determined using high-performance liquid chromatography (HPLC). Rosmarinic acid was the predominant compound in the analyzed extracts. The mixed red and blue LEDs gave the highest levels of polyphenol and rosmarinic acid accumulation (respectively, 24.3 mg/g of DW and 20.0 mg/g of DW), reaching two times greater concentrations of polyphenols and three times greater rosmarinic acid levels compared to the aerial parts of two-year-old intact plants. Similar to WL, ML also stimulated regeneration ability and biomass accumulation effectively. However, the highest total photosynthetic pigment production (1.13 mg/g of DW for total chlorophyll and 0.231 mg/g of DW for carotenoids) was found in the shoots cultivated under RL followed by BL, while the culture exposed to BL was characterized as having the highest antioxidant enzyme activities.

A device-independent method for the colorimetric quantification on microfluidic sensors using a color adaptation algorithm.

Ageneral and adaptable method is proposedto reliably extract quantitative information from smartphone images of microfluidic sensors. By analyzing and processing the color information of selected standard substances, the influence of light conditions, device differences, and human factors could be significantly reduced. Machine learning and multivariate fitting methods were proved to be effective for chroma correction, and a key element was the training ofsample size and the fitting form, respectively. A custom APP was developed and validated using a high-sensitivity chromium ion quantification paper chip. The average chroma deviations under different conditions were reduced by more than 75% in RGB color space, and the concentration test error was reduced by more than half compared with the commonly used method. The proposed approach could be a beneficial supplement to existing and potential colorimetry-based detection methods.

Photoreception and transcriptomic response to light during early development of a teleost with a life cycle tightly controlled by seasonal changes in photoperiod.

Light cues vary along the axis of periodicity, intensity and spectrum and perception of light is dependent on the photoreceptive capacity encoded within the genome and the opsins expressed. A global approach was taken to analyze the photoreceptive capacity and the effect of differing light conditions on a developing teleost prior to first feeding. The transcriptomes of embryos and alevins of Atlantic salmon (Salmo salar) exposed to different light conditions were analyzed, including a developmental series and a circadian profile. The results showed that genes mediating nonvisual photoreception are present prior to hatching when the retina is poorly differentiated. The clock genes were expressed early, but the circadian profile showed that only two clock genes were significantly cycling before first feeding. Few genes were differentially expressed between day and night within a light condition; however, many genes were significantly different between light conditions, indicating that light environment has an impact on the transcriptome during early development. Comparing the transcriptome data from constant conditions to periodicity of white light or different colors revealed overrepresentation of genes related to photoreception, eye development, muscle contraction, degradation of metabolites and cell cycle among others, and in constant light, several clock genes were upregulated. In constant white light and periodicity of green light, genes associated with DNA replication, chromatin remodeling, cell division and DNA repair were downregulated. The study implies a direct influence of light conditions on the transcriptome profile at early developmental stages, by a complex photoreceptive system where few clock genes are cycling.

Influence of lightculture on obtaining planting material of Ipomoea batatas (L.) in vitro

The current article presents the results of the influence of lighting conditions on the morphogenetic potential of Ipomoea batatas (L.) microcuttings in vitro. The studied objects were 4 sweet potato cultivars - Jewel, Purple, Porto Rico, Vinnitsa pink. Microcuttings of I. batatas were cultivated in vitro. We used nutrient medium with mineral salts (according to the prescription of Murashige and Skoog (MS)) and medium only with distilled water (without mineral salts). All nutrient media contained sucrose 2% and agar 0.7%. Hormones were not added to the nutrient media. We studied the influence of the different red (R) and far red (FR) ratios, as well as the red and blue light spectrum on the formation of microshoots and the root system. It was shown that the lighting regimes (R and FR ratio) had a stimulating effect on the roots and shoots growth regardless of the medium composition. Moreover, significant results were obtained under conditions of complete nutrition (mineral salts according to MS) in contrast to the control treatment (fluorescent lamps) and the treatment without salts. The best results were obtained at the R=FR treatment. This light treatment can be recommended for inclusion in the technology of clonal micropropagation of sweet potato. When red and blue spectra were added to normal illumination in different proportions, it did not lead to an increase in the morphogenetic potential of cultivated explants. The growth rate (μ) of the main shoot from axillary buds was about 2 times less than in the control treatment.

Influence of light conditions (colour temperature and illuminance) on the evaluation of root translucency for the application of Lamendin’s age-at-death estimation technique

Estimation of age-at-death represents a central focus in forensic human identification, as it is a key parameter used in the identification of unidentified bodies. In 1992, Lamendin et al. published a simple technique for estimating the age-at-death of adult skeletal remains based on two dental criteria: the gingival regression and the extent of dentine translucency. Although Lamendin’s technique is widely used in forensic contexts and the evaluation of root translucency is a key element in the technique, the light conditions for measuring this parameter have not been adequately established. The aim of the present study is to analyse the influence of colour temperature and illuminance level of a LED light source when root translucency is evaluated to optimize the use of Lamendin’s technique for age-at-death estimation. The results describe how light settings may affect the visual perception of root translucency by different examiners and, therefore, affect the accuracy of the age-at-death estimation methods and techniques based on this parameter.

Recognition Method of Knob Gear in Substation Based on YOLOv4 and Darknet53-DUC-DSNT.

When unattended substations are popular, the knob is a vital monitoring object for unattended substations. However, in the actual scene of the substation, the recognition method of a knob gear has low accuracy. The main reasons are as follows. Firstly, the SNR of knob images is low due to the influence of lighting conditions, which are challenging to extract image features. Secondly, the image deviates from the front view affected by the shooting angle; that knob has a certain deformation, which causes the feature judgment to be disturbed. Finally, the feature distribution of each kind of knob is inconsistent, which interferes with image extraction features and leads to weak spatial generalization ability. For the above problems, we propose a three-stage knob gear recognition method based on YOLOv4 and Darknet53-DUC-DSNT models for the first time and apply key point detection of deep learning to knob gear recognition for the first time. Firstly, YOLOv4 is used as the knob area detector to find knobs from a picture of a cabinet panel. Then, Darknet53, which can extract features, is used as the backbone network for keypoint detection of knobs, combined with DUC structure to recover detailed information and DSNT structure to enhance feature extraction and improve spatial generalization ability. Finally, we obtained the knob gear by calculating the angle between the line of the rotating center point and the pointing point and horizontal direction. The experimental results show that this method effectively solves the above problems and improves the performance of knob gear detection.

A Robust Space Target Detection Algorithm Based on Target Characteristics

In space-based observations, there are large numbers of targets with large size ranges and intensities in a given image. However, the current detection studies mostly emphasize the saliency of targets but neglect their distribution characteristics, which may result in incorrect or missed detection results. In this letter, an effective detection algorithm based on target characteristics is proposed to pursue good multitarget detection performance. First, a space target model is studied to obtain its characteristics. Next, operators are applied to reduce the influence and search for suspected target-center points. Then, local regions around these points are extracted and normalized to reduce the intensity differences among targets and the influence of light conditions. Finally, three features are designed to confirm these suspected regions and their scale information. Furthermore, the threshold setting process is intuitive and significant while keeping the developed method robust in different cases. Compared with other current algorithms, the proposed algorithm achieves superior detection performance in terms of the number of detected targets, accuracy rate, false alarm rate, and computational cost.

Influence of Light Conditions on Microalgae Growth and Content of Lipids, Carotenoids, and Fatty Acid Composition.

Simple SummaryMicroalgae are a valuable natural resource for a variety of value-added products. This determines the relevance of developments aimed at increasing the efficiency of their cultivation. First of all, the growth of microalgae is determined by the impact of light. The main parameters characterizing the light conditions during the cultivation of microalgae are light intensity, duration of lighting, and the use of rays of different spectral composition. Manipulations with the duration of the photoperiod and the use of pulsed light can avoid photodamage of microalgae cells and create conditions for the most efficient absorption of light photons. The optimal light conditions for photosynthesis, growth, accumulation of lipids, fatty acid composition, and carotenes content differ both in different taxonomic groups of microalgae and in different strains of the same species.Microalgae are a valuable natural resource for a variety of value-added products. The growth of microalgae is determined by the impact of many factors, but, from the point of view of the implementation of autotrophic growth, light is of primary importance. This work presents an overview of the influence of light conditions on the growth of microalgae, the content of lipids, carotenoids, and the composition of fatty acids in their biomass, taking into account parameters such as the intensity, duration of lighting, and use of rays of different spectral composition. The optimal light intensity for the growth of microalgae lies in the following range: 26−400 µmol photons m−2 s−1. An increase in light intensity leads to an activation of lipid synthesis. For maximum lipid productivity, various microalgae species and strains need lighting of different intensities: from 60 to 700 µmol photons m−2 s−1. Strong light preferentially increases the triacylglyceride content. The intensity of lighting has a regulating effect on the synthesis of fatty acids, carotenoids, including β-carotene, lutein and astaxanthin. In intense lighting conditions, saturated fatty acids usually accumulate, as well as monounsaturated ones, and the number of polyunsaturated fatty acids decreases. Red as well as blue LED lighting improves the biomass productivity of microalgae of various taxonomic groups. Changing the duration of the photoperiod, the use of pulsed light can stimulate microalgae growth, the production of lipids, and carotenoids. The simultaneous use of light and other stresses contributes to a stronger effect on the productivity of algae.

Plastic leachates lead to long-term toxicity in fungi and promote biodegradation of heterocyclic dye

The hazardous effects of plastic and plastic leachates on organisms, even bacteria, have attracted widespread attention, but only a limited effort has been devoted to explore the response of fungi to plastic leachate induced by light irradiation. Here, we performed plastic leaching experiments to obtain leachates from polyethylene (PE), polyethylene terephthalate (PET) and polypropylene (PP), and optical properties of plastic leachates were analysed to determine the influence of light conditions and plastic materials on that. The effects of plastic leachates on the production of fungal enzyme and the biodegradation of heterocyclic dye by fungi were evaluated. Results indicated that the UV light greatly enhanced the release of leachates from the three plastics. Both plastic polymers and light irradiation affected the plastic-derived dissolved organic carbon (DOC) and their aromaticity, but the molecular weight of plastic leachates showed no dependency on light irradiation types, and PE was the easiest to photo age and leached more DOC. Plastic leachates had no dose-effect on the production of extracellular enzymes by fungi. PE leachates showed long-term toxicities to fungi, and no manganese peroxidase activities were detected after a 42-day incubation, while that of controls were up to 73.64 ± 8.81 U/L. However, the PE and PP leachates greatly promoted methylene blue degradation by the fungi, but PET leachates relieved the decolouration of methylene blue, probably because of the benzene ring structure in the PET monomer. Fusarium oxysporum had a stronger degradation ability than Phanerochaete chrysosporium. Our results indicate that plastic leachates can influence the production and secretion of fungi ligninolytic extracellular enzymes, and regulate the fungal degradation of heterocyclic dye.

Evaluation of Light-Dependent Photosynthetic Reactions in Reynoutria japonica Houtt. Leaves Grown at Different Light Conditions.

The Japanese knotweed (Reynoutria japonica Houtt.) is considered as one of the most aggressive and highly successful invasive plants with a negative impact on invaded habitats. Its uncontrolled expansion became a significant threat to the native species throughout Europe. Due to its extensive rhizome system, rapid growth, and allelopathic activity, it usually forms monocultures that negatively affect the nearby vegetation. The efficient regulation of partitioning and utilization of energy in photosynthesis enables invasive plants to adapt rapidly a variety of environmental conditions. Therefore, we aimed to determine the influence of light conditions on photosynthetic reactions in the Japanese knotweed. Plants were grown under two different light regimes, namely, constant low light (CLL, 40 μmol/m2/s) and fluctuating light (FL, 0–1,250 μmol/m2/s). To evaluate the photosynthetic performance, the direct and modulated chlorophyll a fluorescence was measured. Plants grown at a CLL served as control. The photosynthetic measurements revealed better photosystem II (PSII) stability and functional oxygen-evolving center of plants grown in FL. They also exhibited more efficient conversion of excitation energy to electron transport and an efficient electron transport beyond the primary electron acceptor QA, all the way to PSI. The enhanced photochemical activity of PSI suggested the formation of a successful adaptive mechanism by regulating the distribution of excitation energy between PSII and PSI to minimize photooxidative damage. A faster oxidation at the PSI side most probably resulted in the generation of the cyclic electron flow around PSI. Besides, the short-term exposure of FL-grown knotweeds to high light intensity increased the yield induced by downregulatory processes, suggesting that the generation of the cyclic electron flow protected PSI from photoinhibition.

Influence of Light Conditions and Medium Composition on Morphophysiological Characteristics of Stevia rebaudiana Bertoni In Vitro and In Vivo

We investigated the influence of different conditions (light composition and plant growth regulators (PGRs) in culture media) on the morphophysiological parameters of Stevia rebaudiana Bertoni in vitro and in vivo. Both PGRs and the light spectra applied were found to significantly affect plant morphogenesis. During the micropropagation stage of S. rebaudiana, optimal growth, with a multiplication coefficient of 15, was obtained in an MS culture medium containing 2,4-epibrassinolide (Epin) and indole-3-acetic acid (IAA) at concentrations of 0.1 and 0.5 mg L−1, respectively. During the rooting stage, we found that the addition of 0.5 mg L−1 hydroxycinnamic acid (Zircon) to the MS medium led to an optimal root formation frequency of 85% and resulted in the formation of strong plants with well-developed leaf blades. Cultivation on media containing 0.1 mg L−1 Epin and 0.5 mg L−1 IAA and receiving coherent light irradiation on a weekly basis resulted in a 100% increase in the multiplication coefficient, better adventitious shoot growth, and a 33% increase in the number of leaves. S. rebaudiana microshoots, cultured on MS media containing 1.0 mg L−1 6-benzylaminopurine (BAP) and 0.5 mg L−1 IAA with red monochrome light treatments, increased the multiplication coefficient by 30% compared with controls (white light, media without PGRs).

Effect of different treatments and light quality on Ulmus pumila L. germination and seedling growth

Ulmus pumila L. has potential benefits for erosion control, landscape ornamentals, and the bark contains substances that may have therapeutic value. To determine optimal growth conditions, we investigated the effect of water, sucrose, and exogenous plant growth regulator (6 benzylaminopurine: BA, indolebutyric acid: IBA and gibberellic acid: GA3) treatments as well as light quality (dark, fluorescence, and 2:1 or 4:1 Red:Blue (R:B) LED) on U. pumila seed germination and seedling growth. Seeds soaked in a 3% sucrose solution had the highest germination rate and germination energy in addition to the shortest germination time compared to seeds treated with water or PGRs, except the control. Light quality only affected germination energy, with seeds exposed to 2:1 R:B LED light having the highest germination energy and those exposed to fluorescent light having the lowest. Following transfer to a greenhouse with exposure to natural sunlight, the performance of seedlings varied depending on the light conditions under which they were germinated. In contrast, treatments during the germination stage such as incubation with PGRs had no effect on seedling growth in the greenhouse. Seedlings that germinated under 2:1 or 4:1 R:B LED lights grew taller and had thicker root collars compared to those grown in the dark or under fluorescent lights. The influence of light conditions persisted for at least seven months after the germination, even though the chlorophyll content was similar among seedlings exposed to different growth conditions. Taken together, these results show that light quality in particular during the germination stage can positively affect the growth of the U. pumila seedlings.

INFLUENCE OF ILLUMINATION CHANGES ON IMAGE-BASED 3D SURFACE RECONSTRUCTION

Abstract. The paper investigates the influence of lighting conditions on image-based 3D surface reconstruction, with particular focus on periodic photogrammetric surveys for monitoring and 3D mapping applications. The analyses focus on the accuracy and completeness of each DSM and the daily and hourly repeatability of repeated photogrammetric surveys. Three test sites with rock slopes with a different orientation to the sun and different slope characteristics (slope, pattern, amount of outcropping elements that cast shadows) have been considered to ensure that results can give a general indication of the behaviours in different light conditions. In addition, a simulated virtual test site is included in the study to allow controlled image acquisition and evaluate the effect of the sun’s inclination on the DSM accuracy without influence of other weather conditions. The results show that, although there is an optimal time for the acquisitions, if particularly unfavourable light conditions are excluded, the accuracy reduction with time variation is always below 30%. The repeatability analyses by day and by time highlight a good consistence between DEMs belonging to the same day but acquired at different times and, also, between DEMs acquired at the same time but on different days. This suggests that reliable results can be obtained during continuous monitoring of, for instance, rock faces to identify rockfalls.

Wearable Smart Band for American Sign Language Recognition With Polymer Carbon Nanocomposite-Based Pressure Sensors

The conventional camera-based systems and electronic gloves for gesture recognition are limited by the influence of lighting conditions, occlusions, and movement restrictions. A wearable smart band with integrated nanocomposite pressure sensors has been developed to overcome these shortcomings. The sensors consist of homogeneously dispersed carbon nanotubes in a polydimethylsiloxane polymer matrix prepared by an optimized synthesis process. The sensor band can actively monitor contractions/relaxations of muscles in the arm due to the sensor's high sensitivity in the low forces and stability. The band has eight sensors placed on a stretchable adhesive textile material and connected to a data logger with a multiplexed sensor interface and wireless communication capabilities. The novel smart band was validated by measurements on ten subjects to perform numerical gestures in American sign language from 0 to 9 with ten trials each. The data were recorded at 100 Hz, and a total of 100 datasets were generated for each subject. By feeding the datasets to an extreme machine learning algorithm that selects features, weights, and biases to classify the gestures, an overall gesture recognition accuracy of 93% could be achieved.