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The transition to a low-carbon economy is one of the main challenges of our time. In this context, solar energy, along with many other technologies, has been developed to optimize performance. For example, solar trackers follow the sun's path to increase the generation capacity of photovoltaic plants. However, several factors need consideration to further optimize this process. Important variables include the distance between panels, surface reflectivity, bifacial panels, and climate variations throughout the day. Thus, this paper proposes an artificial intelligence-based algorithm for solar trackers that takes all these factors into account-mainly weather variations and the distance between solar panels. The methodology can be replicated anywhere in the world, and its effectiveness has been validated in a real solar plant with bifacial panels located in northeastern Brazil. The algorithm achieved gains of up to 7.83% on a cloudy day and obtained an average energy gain of approximately 1.2% when compared to a commercial solar tracker algorithm.

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BACKGROUND: This study investigated effects of rapid high-intensity light-curing (3 s) on increasing transdentinal temperature and cell viability. METHODS: A total of 40 dentin discs (0.5 mm) obtained from human molars were prepared, included in artificial pulp chambers (4.5 × 5 mm), and subjected to four light-curing protocols (n = 5), with a Valo Grand light curing unit: (i) 10 s protocol with a moderate intensity of 1000 mW/cm2 (Valo-10 s); (ii) 3 s protocol with a high intensity of 3200 mW/cm2 (Valo-3 s); (iii) adhesive system + Filtek Bulk-Fill Flow bulk-fill composite resin in 10 s (FBF-10 s); (iv) adhesive system + Tetric PowerFlow bulk-fill composite resin in 3 s (TPF-3 s). Transdentinal temperature changes were recorded with a type K thermocouple. Cell viability was assessed using the MTT assay. Data were analyzed using one-way ANOVA and Tukey tests for comparison between experimental groups (p < 0.05). RESULTS: The 3 s high-intensity light-curing protocol generated a higher temperature than the 10 s moderate-intensity standard (p < 0.001). The Valo-10 s and Valo-3 s groups demonstrated greater cell viability than the FBF-10s and TPF-3 s groups and statistical differences were observed between the Valo-3 s and FBF-10 s groups (p = 0.023) and Valo-3 s and TPF-3 s (p = 0.025), with a potential cytotoxic effect for the FBF-10 s and TPF-3 s groups. CONCLUSIONS: The 3 s rapid high-intensity light-curing protocol of bulk-fill composite resins caused a temperature increase greater than 10 s and showed cell viability similar to and comparable to the standard protocol.

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OBJECTIVE: To evaluate the accuracy of five brands of radiometers in reporting the irradiance (mW/cm2 ) from twelve brands of LCUs compared to a 'Gold Standard' (GS) reference obtained from a hand-held laboratory-grade radiometer. MATERIALS AND METHODS: The irradiance was measured from two examples of twelve brands of previously used LCUs on two examples of five brands of dental radiometers. The emission spectrum was also obtained. Irradiance data from each brand of LCU against each meter was analyzed using the Shapiro-Wilk test for normality. The irradiance values were subjected to a two-way ANOVA followed by Bonferroni tests for each LCU brand. Finally, a descriptive analysis was made using a 95% confidence interval around the mean irradiance. RESULTS: The power output from the LCUs ranged from 271 mW to 1005 mW. Among the tested radiometers, only the Bluephase Meter II could accurately report the irradiance from 11 out of the 12 brands of LCU evaluated in this study. When measured using the "GS" system, the mean irradiance values from the two examples of nine brands of previously used LCU were not always within ±10% of the irradiance values stated by the manufacturer. CONCLUSIONS: The mean irradiance values from 9 of the 12 brands of used LCUs were beyond ±10% of the irradiance values stated by the manufacturer. Only the Bluephase Meter II could accurately report the irradiance from 11 out of the 12 brands of LCU evaluated in this study. CLINICAL SIGNIFICANCE: There was a wide range in the power output from the LCUs tested. It was impossible to accurately measure the irradiance from all the LCUs using the dental radiometers examined. However, dental radiometers should still be used in dental offices to monitor the light output from LCUs and verify that they are working correctly before they are used on patients.

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Flowering and fruiting phenology have been infrequently studied in the ever-wet hyperdiverse lowland forests of northwestern equatorial Amazonía. These Neotropical forests are typically called aseasonal with reference to climate because they are ever-wet, and it is often assumed they are also aseasonal with respect to phenology. The physiological limits to plant reproduction imposed by water and light availability are difficult to disentangle in seasonal forests because these variables are often temporally correlated, and both are rarely studied together, challenging our understanding of their relative importance as drivers of reproduction. Here we report on the first long-term study (18 years) of flowering and fruiting phenology in a diverse equatorial forest, Yasuní in eastern Ecuador, and the first to include a full suite of on-site monthly climate data. Using twice monthly censuses of 200 traps and >1000 species, we determined whether reproduction at Yasuní is seasonal at the community and species levels and analyzed the relationships between environmental variables and phenology. We also tested the hypothesis that seasonality in phenology, if present, is driven primarily by irradiance. Both the community- and species-level measures demonstrated strong reproductive seasonality at Yasuní. Flowering peaked in September-November and fruiting peaked in March-April, with a strong annual signal for both phenophases. Irradiance and rainfall were also highly seasonal, even though no month on average experienced drought (a month with <100 mm rainfall). Flowering was positively correlated with current or near-current irradiance, supporting our hypothesis that the extra energy available during the period of peak irradiance drives the seasonality of flowering at Yasuní. As Yasuní is representative of lowland ever-wet equatorial forests of northwestern Amazonía, we expect that reproductive phenology will be strongly seasonal throughout this region.

La fenología de floración y fructificación ha sido poco estudiada en los bosques bajos, lluviosos e hiperdiversos de la Amazonía noroccidental. Estos bosques neotropicales son típicamente llamados no estacionales debido a su clima siempre lluvioso y se asume que son no estacionales con respecto a la fenología. Los límites fisiológicos a la reproducción de las plantas impuestos por la disponibilidad de agua y luz en estos bosques son difíciles de desentrañar debido a que estas variables están a menudo correlacionadas temporalmente y las dos se estudian usualmente por separado, lo que desafía nuestra comprensión de su importancia relativa como desencadenantes de la reproducción. Este es el primer estudio de largo plazo (18 años) de la fenología de floración y fructificación en un bosque hiperdiverso de la Amazonía noroccidental ecuatorial, Yasuní, ubicado al este de Ecuador, y el primero en incluir un completo set de datos climáticos mensuales. Usando censos quincenales de 200 trampas y > 1000 especies, examinamos si la reproducción en Yasuní es estacional a nivel de comunidad y de especies y analizamos las relaciones de las variables ambientales con la fenología. También nos interesaba probar si la estacionalidad en la fenología, en caso de que esté presente está causada por la irradiancia. Tanto a nivel de comunidad como de especies, los datos demuestran una fuerte estacionalidad reproductiva en Yasuní. La floración alcanzó un máximo en septiembre-noviembre y la fructificación alcanzó un máximo en marzo-abril, con una fuerte y consistente señal anual en las dos fenofases. A su vez, la irradiancia y la lluvia fueron también marcadamente estacionales, aunque ningún mes en promedio experimentó sequía (i.e. <100 mm de lluvia). La floración fue positivamente correlacionada con la irradiación, apoyando nuestra hipótesis de que la energía extra disponible durante los periodos de mayor irradiación causa la estacionalidad de la floración en Yasuní. Debido a que Yasuní representa a los bosques ecuatoriales lluviosos de tierras bajas de la Amazonía noroccidental, esperamos que la fenología reproductiva sea fuertemente estacional a lo largo de esta región.

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Objective: Evaluate the mechanical properties of experimental adhesive models with different photoinitiators (PI) polymerized by LED units of different power densities. Material and Methods: Three groups of adhesive models based on HEMA/BisGMA (45/55) were prepared in association with different PI combinations: G2 (control) ­ 2 PI: 0.5% CQ, 0.5% EDMAB; G3 - 3 PI: 0.5% CQ; 0.5% DMAEMA, 0.5% DPIHP; G4 - 4 PI: 0.5% CQ; 0.5% EDMAB; 0.5% DMAEMA; 0.5% DPIHP. The three formulations were polymerized at two different LED power densities: 550 mW/cm2 and 1200 mW/cm2. The degree of conversion (DC) of adhesive monomers was monitored in situ through the FTIR for 600 s. Specimens were prepared for each formulation for analysis mong adhesive systems (G2

Objetivo: Avaliar as propriedades mecânicas de modelos adesivos experimentais com diferentes fotoiniciadores (PI) polimerizados por unidades de LED de diferentes densidades de energia. Material e Métodos: Três grupos de modelos adesivos baseados em HEMA/BisGMA (45/55) foram preparados em associação com diferentes combinações de PI: G2 (controle) ­ 2 PI: 0,5% CQ, 0,5% EDMAB; G3 - 3PI: 0,5% CQ; 0,5% DMAEMA, 0,5% DPIHP; G4 - 4 PI: 0,5% CQ; 0,5% EDMAB; 0,5% DMAEMA; 0,5% DPIHP. As três formulações foram polimerizadas em duas densidades de potência de LED: 550 mW/cm2 e 1200 mW/cm2. O grau de conversão (DC) dos monômeros adesivos foi monitorado in situ através do FTIR durante 600 s. Amostras foram preparadas para cada formulação para análise de resistência à flexão (FS), módulo de elasticidade (ME), sorção (SOR) e solubilidade (SOL). Os dados foram submetidos aos testes ANOVA 2-fatores e Tukey (5%). Resultados: DC: houve diferença significativa entre os sistemas adesivos (G2

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Rituximab is a monoclonal antibody used in the treatment of lymphoma non-Hodgkin. This mAb is photosensitive as it is administrated to the patient by infusion/perfusion; therefore, photostability is a decisive factor in the efficacy of this biologic. To better understand the photodegradation mechanisms of Rituximab, this biologic was exposed to different irradiance conditions. We show in this study that this mAb photodegrade proportionally to irradiance intensities. The main modifications of Rituximab by irradiance correlate to the increase in aggregates, decrease in its Tm, acidic charge variants, oxidation of the Trp (36) in the heavy chain, and decrease in complement-dependent cytotoxicity (CDC) potency. To understand the relationship between real-life photo-exposition conditions and ICH standardized light tests, a full characterization was set up. Worst photo-stress cases were evaluated, 1 and 2 h under direct sunlight through a window, mimicking the ID65 electromagnetic radiation profile. Our results show that only exposition to direct sun irradiance during 2 h, (≈ 150 kluxes•h), increases critically soluble and insoluble aggregates, diminishing Tm, increasing acidic charge variants, and the photooxidation of the Trp (36) in the heavy chain measured by peptide mapping-RP-UPLC-MS. A decrease in CDC below 80% resulted under this condition, which correlates with physicochemical analyses. While inside light-room exposition (similar to ICH test) and ICH conditions do not have any contribution to the degradation of Rituximab measured by these physicochemical and biological analytical methods. These results indicate that exposition of Rituximab to below ≈ 75 kluxes•h of sun light cannot photodegrade critically this biologic inside of its primary container.

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Mixotrophic protists display contrasting nutritional strategies and are key groups connecting planktonic food webs. They comprise constitutive mixotrophs (CMs) that have an innate photosynthetic ability and non-constitutive mixotrophs (NCMs) that acquire it from their prey. We modelled phototrophy and phagotrophy of two mixotrophic protists as a function of irradiance and prey abundance. We hypothesised that differences in their physiology (constitutive versus non-constitutive mixotrophy) can result in different responses to light gradients. We fitted the models with primary production and bacterivory data from laboratory and field experiments with the nanoflagellate Chrysochromulina parva (CM) and the ciliate Ophrydium naumanni (NCM) from north Andean Patagonian lakes. We found a non-monotonic response of phototrophy and phagotrophy to irradiance in both mixotrophs, which was successfully represented by our models. Maximum values for phototrophy and phagotrophy were found at intermediate irradiance coinciding with the light at the deep chlorophyll maxima in these lakes. At lower and higher irradiances, we found a decoupling between phototrophy and phagotrophy in the NCM while these functions were more coupled in the CM. Our modelling approach revealed the difference between both mixotrophic functional types on the balance between their nutritional strategies under different light scenarios. Thus, our proposed models can be applied to account how changing environmental conditions affect both primary and secondary production within the planktonic microbial food web.

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Global Horizontal Irradiance was measured using a thermopile-type pyranometer during more than three years using a sample time of two seconds, with the purpose of capturing fast transient events of irradiance which are notable in tropical regions as the one where these data were collected: Bogotá, Colombia. The date and time of each measurement were registered along with the irradiance values. In addition, other related quantities were calculated and included for each one of the measurement instants: Optical Air Mass, Zenith angle, Extraterrestrial Solar Irradiance, and Clearness Index. Daily aggregated statistics of irradiance were calculated and are provided here too. Data points corresponding to nights were discarded. The raw data was analyzed to remove incomplete days, to guarantee that daily statistics are accurate and meaningful. After this data cleaning process, 1016 complete days remain, having a total of 21,959,912 data points. These data are useful for studying the effect of irradiance transients over photovoltaic systems, including power electronics, batteries and electric loads; it can also be used in studies about the stability of the radiative regime or the variability of irradiance such as Avila et al. (2019) (where part of these data was effectively used) and other related works cited there.

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The incidence angle of solar irradiance is an important parameter for sizing and locate photovoltaic systems, which affects the installation design and has a high influence in the power production of photovoltaic panels. This angle is traditionally estimated considering the geographical position, however, this approach ignores the existence of local elements that affect the generation, such as weather conditions, topography, constructions with high reflection, among others. Therefore, this work presents the design and construction of a measurement device with nine irradiance sensors, which are located at different angles on two orthogonal axes within a semisphere. Since the angles of the sensors are known, a model to determine the direction of the maximum incidence irradiance, at each instant of time, can be calculated from the on-site measurements. In this way, it is also possible to calculate the panel inclination and orientation producing the maximum power for a particular location. The device acquires the irradiance magnitude in the nine sensors in real time, and it is transmitted using the Internet to simplify data recollection. Finally, the device uses a low-cost platform, which makes possible the adoption of this solution in a wide range of applications, e.g. design, diagnostic or reconfiguration of PV arrays.

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The development and optimization of renewable energy systems are some of the most necessary topics to advance towards secure and sustainable energy models. Photovoltaic energy is one of those sustainable options that could contribute to the reduction of greenhouse gas emissions. The optimal angle of solar incidence producing the highest absorption in a day is an important parameter to install photovoltaic systems. This value is often estimated using simulation models based on geographic location; however, those models ignore the influence of nearby obstruction objects, albedo, and local weather conditions. Such a problem is addressed in this work by designing a system to estimate the optimum angle of solar incidence for the photovoltaic panels. The system is based on an arrangement of 33 measurement points spaced in arcs every 45 degrees in azimuth and every 22.5 degrees in elevation, which provides a wide range for analysis. The light captured by each optical fiber is transmitted to a flat array where the power is measured using a single RGB camera.

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Microalgae are a valuable natural resource for a variety of biocompounds such as carotenoids. The use of different light spectra and irradiance has been considered as a promising option to improve the production of these compounds. The objective of this study was to evaluate the influence of different wavelengths (white, red, and blue) and irradiances (80 and 350 µmol photons/m2/s) on the photosynthetic state, total carotenoids and lutein productivity (HPLC), lipids (Nile red method) and antioxidant activity (DPPH) of the microalgae Muriellopsis sp. (MCH-35). This microalga, which is a potential source of lutein, was isolated from the coastal desert of Antofagasta, Chile, and adapted to grow in seawater. The results indicate that the culture exposed to high-intensity red light showed the highest biomass yield (2.5 g/L) and lutein productivity (>2.0 mg L−1day−1). However, blue light was found to have a stimulating effect on the synthesis of lutein and other carotenoids (>0.8% dry wt). Furthermore, a direct relationship between lipid accumulation and high light intensity was evidenced. Finally, the highest antioxidant activity was observed with high-intensity white light, these values have no direct relationship with lutein productivity. Therefore, the findings of this study could be utilized to obtain biocompounds of interest by altering certain culture conditions during the large-scale cultivation of MCH-35.

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OBJECTIVES: This study characterized a violet LED light (V-LED; bright max whitening) tooth whitening device and evaluated its efficacy on stained enamel compared to hydrogen peroxide (HP). MATERIALS AND METHODS: Characterization of the V-LED beam profile was performed using a laser beam-profiler. The irradiance was measured throughout an exposure cycle at 0- and 8-mm distances using an integrating sphere and a spectral radiometer. Bovine enamel/dentin blocks stained with black tea (BT), cigarette smoke (CS), or without staining (CONT) were subjected to V-LED or 40% HP (n = 10/group). Color parameters (ΔL, Δa, Δb, and ΔE00) were measured using a digital spectrophotometer. Light transmission was estimated through 1-mm-thick bovine enamel slices (n = 5). ΔL, Δb, ΔE00, and irradiance were analyzed by two-way ANOVAs and Tukey's tests, Δa by Kruskal-Wallis and Mann-Whitney tests, and light transmission by t-test (α = 5%). RESULTS: Heterogeneous beam distribution was observed for the emitting V-LED chips. After 20 sequential exposures, irradiance levels were reduced 25-50%, regardless of the distance from V-LED. Localized irradiance values were statistically different between beam locations and different distances from the target. V-LED produced lower ΔE00, ΔL, Δa, and Δb values than HP for CONT and BT, with no differences for CS. Light transmittance decreased approximately 98% through 1-mm thick enamel. CONCLUSIONS: V-LED irradiance was heterogeneous and decreased throughout the exposure cycles and was also greatly reduced with increasing tip distance. V-LED produced a significantly lower whitening effect on BT and control teeth. CLINICAL RELEVANCE: This study contributes to the knowledge of V-LED and its clinical use.

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The coexistence of plant species in tropical rainforests is related to specific abiotic resources, varying according to the occurrence microhabitat of each species. Light quality is the main abiotic factor influencing germination of small seeds; however, studies often do not discriminate its effect from that of light irradiance. This study compared specific requirements for seed germination of ten small-seeded species, with restricted occurrence in only one of three contrasting microhabitats: forest understorey, edge of clearings and open areas. Laboratory experiments were carried out to test temperature regime (constant or fluctuating), light quality (R:FR) and light irradiance (PAR), which reproduce high and low conditions commonly found in the microhabitats. Seed germination of all species occurred between 20 and 30 °C, only seeds of open area species were able to germinate at 35 °C and no species required alternating temperatures to germinate. Irrespective of species and microhabitat, a decrease in the R:FR reduced the germination percentage; however, there were differences in the capacity to germinate at low R:FR. The values of R:FR50% were higher for open area and edge species (0.441-0.345) than for understorey species (0.181-0.109), with few exceptions. For all species and most of the tests, germination was not influenced by PAR. Light quality is the most important light signal for germination of small seeds; irradiance has little effect. Our results suggest two distinct patterns of germination for small-seeded species: open area and edge species are light-demanding and require high R:FR to germinate, while understorey species are shade-tolerant and germinate at low R:FR. These differences are responsible for distinct microhabitat occurrence and help to explain the coexistence of species in tropical forests.

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Biological invasions have become increasingly prevalent in marine ecosystems, modifying biodiversity and altering the way ecosystems function. Understanding how variation in environmental factors influences the success of non-native species, especially their early life stages, can be a crucial step in identifying habitats that are under threat of invasion, and in predicting how rapidly and far these species may spread once they arrive in novel habitats. The invasive marine macroalga Sargassum horneri was first observed in Long Beach Harbor, CA, USA in 2003, and has since spread throughout the Southern California Bight and along the Baja California Peninsula, MEX where it now forms dense stands on subtidal rocky reefs and displaces native habitat-forming macroalgae. We examined how variation in temperature, nutrients, and irradiance affect survival, growth, and development in S. horneri early life stages over a three-week period. Our experimental treatments consisted of orthogonally crossed temperatures (10, 15, 20, and 25°C), nutrient concentrations (ambient and nutrient-enriched seawater), and irradiances (50 and 500 µmol photons · m-2 · s-1 ). Overall, temperature exerted the greatest influence on S. horneri's germling and juvenile life stages, with moderate temperatures facilitating their greatest survival, growth, and development. In contrast, fewer germlings developed fully under the lowest or highest temperatures, and juvenile survival and growth were reduced, especially when combined with low irradiances. Together, our data suggest that ocean temperatures of or below 10˚C and of or above 25°C may slow, but likely not stop, S. horneri's northward and southward expansion along the California and Baja California coasts.

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The study evaluated the potential and antioxidant stability of nanoencapsulated carotenoid-rich extract (CE) from Cantaloupe melon (EPG). DPPH and ABTS radical scavenging assays were used to investigate the nanoencapsulation effect on antioxidant potential. CE and EPG stability were evaluated at 25 °C and 5 °C, with and without light (1600 lx) for 60 days, determining the ß-carotene concentration by UHPLC and antioxidant potential by ABTS. The antioxidant potential of carotenoids increased after nanoencapsulation (57-59%). After 60 days, there was low retention of ß-carotene (0-43.6%) in the CE, mainly at 25 °C light (0.00%) and dark (10.0%), and total loss of activity in the four conditions. EPG preserved the ß-carotene concentration in the dark at 25 °C (99.0%) and in the light (83.1%) and dark (99.0%) at 5 °C, maintaining the antioxidant potential (68.7-48.3%). Therefore, EPG enhanced and stabilized the antioxidant potential of carotenoids, beneficial to human health.

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Purpose To evaluate the effect of glass-reinforced ceramics (leucite and lithium disilicate) with different thicknesses (1, 2, and 3 mm) on the wavelength and irradiance spectrum of blue and violet lights. In addition, the effect of the ceramics on four current light-curing units (LCUs) was evaluated: a halogen lamp, a single peak LED, and two multi-peak LEDs.Methods Ceramic discs of different thicknesses (1, 2, and 3 mm) were obtained from computer-aided design and computer-aided manufacturing (CAD-CAM) blocks. The irradiance, radiant exposure, and emission spectrum of the four LCUs were analyzed using a spectrometer-based instrument. To evaluate the violet and blue lights, a specific device that provides a narrow emission spectrum was used.Results The ceramics reduced the irradiance of all the tested LCUs. However, the wavelength of the transmitted light was only altered slightly. The effect of leucite and lithium disilicate varied according to the type of LCU and thickness of the ceramic disc evaluated .Conclusions From the results, it could be concluded that the thickness of the leucite and lithium disilicate ceramic significantly reduced the irradiance of the light emitted by the LCUs, with minimal changes on the wavelength spectrum of the lights. The effects of the ceramic on irradiance and transmitted wavelengths of the blue and violet lights was slightly different.

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Accurate measurements of diffuse irradiance are essential to design a solar photovoltaic system. However, in-situ radiation measurements in Colombia, South America, can be limited by the costs of the implementation of meteorological stations equipped with a pyranometer mounted on a sun tracker with a shading device, which is required to measure diffuse irradiance. Furthermore, the databases found in Colombia contain missing data, which raises the need for implementing models that are trained with very few features. In this paper, we introduce a methodology based on simple angle calculations and a regression model to predict half-hourly diffuse horizontal solar irradiance from only the measure of global horizontal irradiance and a geographic coordinate as inputs. Using measurements taken from the national solar radiation database for 6 different sites in Colombia and state-of-the-art machine learning models for regression, we validated the accuracy prediction of the proposed methodology. The results showed a prediction error ranging from 5.86 to 9.36 [W/m 2], and a coefficient of determination ranging from 0.9974 to 0.9983. The data-set used along with the feature engineering process and the deep neural network model created can be found in a Github repository referenced in the paper.

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Currently, photobiomodulation therapy (PBMT) is gaining space in the scientific and clinical environment. To help elucidate the importance of irradiance, this study evaluated the effect of two different PBMT irradiances (3.5 and 90 mW/cm2), given a fixed wavelength of 630 nm and a dose of 2 J/cm2, on mechanical hyperalgesia following Complete Freund's Adjuvant (CFA) intraplantar (i.pl.) injection in mice. Additionally, we investigated the role of peripheral opioid and endothelin-B receptors (ETB-R), as well as sex differences in treatment outcome. Different groups of male or female mice were evaluated 6 and 96 h after CFA. Mechanical hyperalgesia was evaluated 30 min after treatments. Naloxone or Bq-788 administration, fifteen minutes before PBMT or Sarafotoxin S6c, helped determine the involvement of peripheral opioid and ETB-Rs on PBMT. Lastly, ETB-Rs skin immunocontent in both sexes was quantified after PBMT consecutive daily treatments. PBMT at an irradiance of 90 mW/cm2, was more effective than 3.5 mW/cm2. Bq-788 and naloxone administration prevented the effects of PBMT and SRTX S6c; however, PBMT did not influence peripheral ETB-Rs immunocontent. The results suggest that irradiance influences PMBT effect; and that activation of ETB-R play a role in peripheral PBMT opioid induced analgesia. Lastly, PMBT effects do not appear to be sex-dependent.

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Abstract The growth in the use of solar energy has encouraged the development of techniques for short-term prediction of solar photovoltaic energy generation (PSPEG). Machine learning with Artificial Neural Networks (ANNs) is the most widely used technique to solve this problem. However, comparative studies of these networks with distinct structural configurations, input parameters and prediction horizon, have not been observed in the literature. In this context, the aim of this study is to evaluate the prediction accuracy of the Global Horizontal Irradiance (GHI), which is often used in the PSPEG, generated by ANN models with different construction structures, sets of input meteorological variables and in three short-term prediction horizons, considering a unique database. The analyses were performed with controlled environment and experimental configuration. The results suggest that ANNs using the input GHI variable provide better accuracy (approximately 10%), and their absence increases error variability. No significant difference (p>0.05) was identified in the prediction error models trained with distinct meteorological input data sets. The prediction errors were similar for the same ANN model in the different prediction horizons, and ANNs with 30 and 60 neurons with one hidden layer demonstrated similar or higher accuracy than those with two hidden layers.

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solar irradiance and cell temperature are the most significant aspects when assessing the production of a photovoltaic system. To avoid the need of specific sensors for quantifying such parameters, recent literature presents methods to estimate them through electrical measurements, using the photovoltaic module itself as a sensor. This work presents an application of such methods to data recorded using a research platform at University of Corsica, in France. The methods and the platform are briefly presented and the results are shown and discussed in terms of normalized mean absolute errors (nMAE) and root mean square errors (nRMSE) for various irradiance and cell temperature levels. The nMAE (and nRMSE) for solar irradiance are respectively between 3.5% and 3.9% (4.2% and 4.7%). Such errors on computed irradiance are in the same order of magnitude as those found in the literature, with a simple implementation. For cell temperatures estimation, the nMAE and nRMSE were found to be in the range 3.4%-8.2% and 4.3%-10.7%. These results show that using such methods could provide an estimation for the values of irradiance and cell temperature, even if the modules are not new and are not regularly cleaned, but of course not partially shaded.

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