Maximum Light Intensity Research Articles

Technical Reports: Methods—The Application of Temperature and Light Intensity as Intermittency Sensors in a Temporary Pond

AbstractAs climate change progresses, hydrological regimes of temporary and perennial water bodies are projected to change, affecting biodiversity and ecosystem functioning. Researchers have successfully employed the use of satellite imagery, camera traps and site visits to map these changes in hydrological regimes. Data loggers of conductivity have also been used in mapping hydrological regimes, but the use of data loggers of temperature and light intensity is uncommon. Using validated data of 213 days of the aquatic and terrestrial phases of a temporary pond, we show that metrics of temperature and light intensity can be used to discern hydrological state. The aquatic phase had lower measures of both parameters when compared to the terrestrial phase. This was attributed to the high specific heat of the aquatic environment and the absorption and redirection of light in water. The most powerful metrics in discerning hydrological state were diel temperature range, diel maximum temperature and light intensity standard deviation. Greater distinctive power was obtained through the use of multiple metrics of the parameters. In addition, key events such as flooding and drying were identifiable within metrics of both parameters. High‐resolution temperature and light intensity data are able to aid in understanding the dynamics of hydrological state and can be used to monitor ecosystem functions amid changes in temporary and perennial water bodies.

A high-stable self-referenced PGC demodulation algorithm for fiber-optic interferometric sensor

A self-referenced phase generation carrier (SR-PGC) algorithm is proposed in this paper. The influence related to modulation depth, light intensity and carrier phase delay can be theoretically eliminated. In classical PGC algorithm, the orthogonal components are obtained by mixing the detected signal with the proper multiples of carrier frequency and low-pass filtering, which are related to several parameters (modulation depth, light intensity, carrier phase delay, etc.). We notice that the differential signals of them also contain the parameters above. In the proposed SR-PGC algorithm, the orthogonal components are taken as the reference signals, and they are divided by their own differential signals, so that the parameters above can be eliminated in real-time. The algorithm was implemented in the field-programmable gate array-based electronic processing circuit, and a large dynamic range of 178.2 dB@200 Hz was achieved. Within 1 kHz bandwidth, the phase resolution reached 2 μrad/Hz1/2. A maximum light intensity rejection ratio of 37.0 dB was obtained. While the modulation depth is between 1 rad and 3.5 rad, the signal-to-noise-and-distortion (SINAD) and the total harmonic distortion (THD) can reach as good as 74.0 dB and −76.8 dB respectively, and the fluctuation of the SINAD and THD in 4 h were both within 1.2%. These experimental results prove the high stability of SR-PGC algorithm.

Graded optogenetic activation of the auditory pathway for hearing restoration

Optogenetic control of neural activity enables innovative approaches to improve functional restoration of diseased sensory and motor systems. For clinical translation to succeed, optogenetic stimulation needs to closely match the coding properties of the targeted neuronal population and employ optimally operating emitters. This requires the customization of channelrhodopsins, emitters and coding strategies. Here, we provide a framework to parametrize optogenetic neural control and apply it to the auditory pathway that requires high temporal fidelity of stimulation. We used a viral gene transfer of ultrafast targeting-optimized Chronos into spiral ganglion neurons (SGNs) of the cochlea of mice. We characterized the light-evoked response by in vivo recordings from individual SGNs and neurons of the anteroventral cochlear nucleus (AVCN) that detect coincident SGN inputs. Our recordings from single SGNs demonstrated that their spike probability can be graded by adjusting the duration of light pulses at constant intensity, which optimally serves efficient laser diode operation. We identified an effective pulse width of 1.6 ms to maximize encoding in SGNs at the maximal light intensity employed here (∼35 mW). Alternatively, SGNs were activated at lower energy thresholds using short light pulses (<1 ms). An upper boundary of optical stimulation rates was identified at 316 Hz, inducing a robust spike rate adaptation that required a few tens of milliseconds to recover. We developed a semi-stochastic stimulation paradigm to rapidly (within minutes) estimate the input/output function from light to SGN firing and approximate the time constant of neuronal integration in the AVCN. By that, our data pave the way to design the sound coding strategies of future optical cochlear implants.

Evaluation of Virtual Reality Perimetry and Standard Automated Perimetry in Normal Children.

The Olleyes VisuALL-K is a pediatric videogame-based static threshold perimeter using a virtual reality headset. We determined normal threshold sensitivities for the 24-2 test locations using the virtual reality perimetry (VRP) and also tested patients on the Humphrey Field Analyzer (HFA). Patient satisfaction for the two instruments was compared. This exploratory study tested 50 normal pediatric participants aged 8 to 17 years on the HFA and VRP. The main outcome measure was threshold sensitivity at the 24-2 test locations for the two instruments. The mean participant age was 13.0 ± 2.6 years; 50% were female. The threshold values for VRP are reported as measured on the device and after conversion to an HFA-equivalent scale. Age-adjusted thresholds showed a mean sensitivity of 31.8 ± 1.1 dB (46.1 ± dB HFA equivalent) diminution from the maximum light intensity in the VRP and 31.0 ± 1.5 dB diminution from the maximum light intensity in the HFA; interparticipant variability in mean threshold sensitivity was 2.7 ± 0.4 dB for the VRP and 2.7 ± 0.6 dB for the HFA. The HFA demonstrated decreased threshold sensitivity with increasing eccentricity, whereas the VRP threshold did not seem to vary with eccentricity. Mild age effects on threshold sensitivity were seen in the VRP and the HFA (R2 = 0.11, P < 0.001 and R2 = 0.05, P < 0.05, respectively). The mean time to completion for VRP and HFA was 7.6 ± 1.5 and 5.3 ± 0.9 min/eye, respectively (P < 0.0001). Patient satisfaction scores favored VRP (P < 0.01) despite the longer test duration. The Olleyes game-based VRP and HFA can be used to map out the peripheral vision in normal children. The VRP has a higher patient satisfaction when used in children than the HFA. The portability of the test allows it to be performed in a myriad of environments, lending a flexibility that can benefit this population. This virtual reality perimetry device provides an alternative to the Humphrey Field Analyzer for children.

Efeect of Environmental Parameters on Chrysanthemum Different Colour Low Tunnel Shade Nets and Different Colour Mulches

Shade nets are used for controlling the crop growth and improving crop productivity. A field experiment was conducted under shade net to determine the effect of environmental parameters on chrysanthemum under on different colour low tunnel shade nets. The experiment had split plot design consisting of different colour shade nets as main plots i.e., white shade net, green shade net, black shade net and open field condition and different mulches as a sub plots i.e., white colour plastic mulch, silver colour plastic mulch, black colour plastic mulch, jute mulch and no mulch. White colour shade net significantly increased the soil moisture and lowered the soil temperature compared to other colour shade nets. During the experimental period, maximum temperature (37.90 °C) was recorded under control condition followed by black shade net (35.80 °C) and green shade net (34.60 °C). Minimum temperature (33.00 °C) was recorded under white shade net. Maximum relative humidity (86.20 %) was recorded under white shade net followed by green shade net (82.30 %) and black shade net (79 %). Minimum relative humidity (77 %) was recorded under control condition. Maximum light intensity (49600 Lux) was recorded under control condition followed by white shade net (46800 Lux) and green shade net (37,000 Lux). Minimum light intensity was recorded under black shade net (33210 Lux). The results of biometric parameters depicted higher growth and yield parameters for chrysanthemum grown under white shade net with white plastic mulch. The yield of Chrysanthemum was increased in white shade net (8.75 t ha-1) than the black shade net (4.43 t ha-1). Chrysanthemum grown in open fields and without mulch produced lower growth and yield.

A Sensor With Coating Pt/WO Powder With an Erbium-Doped Fiber Amplifier to Detect the Hydrogen Concentration

A highly sensitive hydrogen sensor (HS) coated with Pt/WO3 powder with an erbium-doped fiber amplifier (EDFA) is proposed and experimentally demonstrated. The sensing head is constructed by splicing a short Section of tapered small-diameter coreless fiber (TSDCF diameter of 62.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> and tapered to 14.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> ) between two single-mode fibers (SMFs). The Pt/WO3 powder adheres to the surface of polydimethylsiloxane (PDMS) film coated on the TSDCF structure, which is sensitive to hydrogen. An EDFA is introduced into the sensor system to improve the quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> -factor) of the output spectrum and thus improve the sensor’s resolution. As the hydrogen concentration varies from 0% to 1.44%, the measured maximum light intensity variation and the sensor’s sensitivity are −32.41 dB and −21.25 dB/%, respectively. The sensor demonstrates good stability with the light intensity fluctuation of < 1.26 dB over a 30-min duration.

High-precision measurement on the extinction ratio of linear polarizers

The extinction ratio is an important optical parameter that determines the quality of the linear polarizers. Here, we propose a high-precision measurement method for linear polarization extinction ratio, which is based on two uniform and consistent unknown linear polarizers, an integrating sphere, a precision turntable, and a spectrometer. The precision turntable is used to change the relative angle between the two unknown linear polarizers. The Mueller matrixs with the optical parameters including relative angles of the two unknown linear polarizers are established, and the linear polarization extinction ratio is obtained by numerical calculation. This method does not require a reference linear polarizer with a high extinction ratio, nor does it require fine adjustment of the angle between the two unknown linear polarizers to obtain the maximum and minimum light intensity grayscale response of the detector, which has an important engineering significance for high-precision measurement of linear polarization extinction ratio.

Impacts of artificial light at night on the vegetative growth and yield attributes of fodder oat (Avena sativa)

Aim: The present investigation was designed to study the impact of artificial light at night on the phenological phases and yield contributing traits of fodder oat variety Kent for holistic breeding along the roadsides or highways. Methodology: The experiment was conducted at Central Research Farm of ICAR-IGFRI, Jhansi, India, in a plot under natural conditions. The treatment Lc (controlled) was under natural conditions receiving normal daylight and dark periods. However, treatment L1 (300-350 lux), L2 (200-300 lux), L3 (100-200 lux), and L4 (10-50 lux) were different light affected areas having distances 0, 5, 10, and 15 m from the light source. Duncan's test, OPSTAT, and SPSS version 16.0 software were used for statistical analysis. Results: The vegetative growth parameters such as plant height, total leaf area, flag leaf area, days to 50% flowering, panicle length, total dry biomass, and test weight were increased linearly as the distance increased from the artificial light source (minimum value for L1 treatment and maximum for Lc). However, plant population per meter square was maximum for L1 treatment and minimum for local control (Lc; no night light effect). Moreover, it is the first report of artificial light at night on the fodder oat from India and concluded that night light significantly affects the plant phenology and yield potential, and opens a new research paradigm on plant-artificial light at night interactions. Interpretation: Plants close to the light source received maximum intensity of night light (L1) than distantly located treatments (L2, L3, and L4). Artificial light at night-time had adverse effects on the yield-contributing traits and showed a significant negative relationship. Key words: Artificial light, Fodder oat, Light intensity, Morphological traits, Night time

Effect of Direction and Distance of Moringa oleifera on Growth and Yield of Cabbage (Brassica oleracea)

A field experiment was conducted at the moringa-based experimental farm of the Department of Agroforestry and Environment, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur from November 2020 to September 2021. The aim of the study was to assess how well cabbage performed and adapted to various orientations and distances from the moringa tree. The experiment was carried out in a Randomized Complete Block Design (RCBD) with three replications. Four different directions along with one control plot were used as factor A and different distances from tree base was treated as factor B. The data of some ecophysiological parameters like maximum light intensity and soil temperature were noticed in south direction and the widest distance from tree base. The highest soil moisture was found at north direction. Most of the growth parameters showed better performance in open field compared to shade condition. In the case of interaction effect, the south direction and the widest distance (180 cm) from moringa tree base showed the highest number of outer leaves, head length, width, head diameter, head length, and head weight compared to other directions and distances. Concurrently, the maximum total yield and marketable yield were recorded from 180 cm in south direction whereas the lowest yield was found at the closest distance (80 cm) and east direction. The marketable yield of south, west, north, and east directions were reduced by 8.43, 14.87, 23.86 and 31.52% as compared to open field. At 130 cm and 80 cm distance the yield was reduced by 16.42 and 32.26% as compared to 180 cm distance from tree base. The current findings suggested that cabbage may be grown in partial shade in moringa-based agroforestry production systems without enduring significant yield losses.

Interference enhancement effect in a single Airyprime beam propagating in free space.

An analytical expression of a single Airyprime beam propagating in free space is derived. Upon propagation in free space, a single Airyprime beam in arbitrary transverse direction is the coherent superposition of the Airyprime and the Airy-related modes, which results in the interference enhancement effect under the appropriate condition. The Airy-related mode is the conventional propagating Airy mode with an additional π/2 phase shift and a weight coefficient of half the normalized propagation distance. Due to the peak light intensity in the initial plane being set to be 1, the strength of interference enhancement effect is characterized by the maximum light intensity. The maximum light intensity of a single Airyprime beam propagating in free space is independent of the scaling factor and is only decided by the exponential decay factor. When the exponential decay factor is above the saturated value, the interference enhancement effect disappears. When the exponential decay factor decreases from the saturated value, the maximum light intensity of a single propagating Airyprime beam increases, and the position of maximum light intensity is getting farther away. With the increase of the scaling factor, the position of maximum light intensity of a single propagating Airyprime beam is extended. The intensity distribution and the transverse Poynting vector of a single propagating Airyprime beam are demonstrated in different observation planes of free space. The flow direction of transverse energy flux effectively supports the interference enhancement effect of a single propagating Airyprime beam. The Airyprime beam is experimentally generated, and the interference enhancement effect is experimentally confirmed. The interference enhancement effect is conducive to the practical application of a single Airyprime beam.

Thermal design strategy for enhanced freshwater harvesting with interfacial evaporation

Solar driven interfacial evaporation is considered to be a low-carbon, environment-friendly technology for achieving efficient evaporation, but the solar still equipped with the interfacial evaporation structure is found to process low fresh water production rate and production efficiency. In this work, an optimization scheme for the interfacial evaporation structure of the solar still is proposed through the theoretical analysis of the heat and mass transfer process of the interfacial evaporation solar still. The theoretical results show that there are significant differences in the optimization design between the interfacial evaporation solar still and conventional solar stills. The fresh water production rate of interfacial evaporative solar still is less sensitive to the insulation performance of the solar still, while is greatly affected by the convective heat transfer process inside and outside the solar still. The solar still with interfacial evaporation structure can reduce the use of insulation materials to improve the illumination area and reduce the construction cost, without affecting the production efficiency of fresh water. Under the input energy intensity of 1 kW·m−2, when the convective heat transfer process inside the solar still is strengthened, the theoretical fresh water production rate of the interfacial evaporation solar still can be increased by 28 %, and the efficiency can reach 73 %. However, different from the optimization results of the traditional solar still, the enhancement of convective heat transfer process outside the glass cover will lead to the decline of the efficiency of the solar still. The experimental results show that in a monoclinic interfacial evaporation solar still with an evaporation surface area of 60 cm * 60 cm, a high system performance can be achieved by attaching a thin layer of insulation material to the inner wall and using a 2 W fan for forced convection of internal air. Under the outdoor environment with the maximum light intensity of 1 kW·m−2, the production efficiency of fresh water can be stabilized at 62.6 %. This work provides important guidelines for the design and optimization of solar still with interfacial evaporation structure.

The effect of the photoacoustic Field-Photoacoustic cell coupling term on the performance of the gas detection system

The optimization of the photoacoustic cell (PAC) has always been a research hotspot in the photoacoustic spectroscopy (PAS) based gas detection technology. Herein, a new influential factor of the PA signals intensity, photoacoustic field (PAF)-PAC coupling term was proposed. In addition, the simulation of the sound pressure distribution in the PAC and the PAS gas detection experiment were carried out. The results show that: the length LC and radius RC of the resonator both have an impact on the sound pressure distribution, the strongest sound pressure intensity appears when LC = 95 mm. Besides, when LC is in the range of 35 ∼ 65 mm, the sound pressure intensity decreases with the increased RC, whereas it increases with RC when LC is in the range of 80 ∼ 125 mm. With the shortening of the focal length F0, the dimension of the light beam and the maximum light intensity reduces and enhances, respectively. In particular, when F0 = 16 mm, the integral value along the major axis of the light spot has the peak value, which also changes with the distance l2 from the laser head to the convex lens, and the peak value appears when l2 = 4 mm. In addition, the optimal response of the gas detection system (GDS) occurs when l1 = 0 mm, l2 = 2 mm, l3 = 2 mm. LC has a significant impact on the representative signal intensity(RSI), and the influence is mainly result from the PAF-PAC coupling term. However, the effect of the RC on the RSI can be approximately negligible.

Agroforestry: Viable alternatives for ensuring green fodder production around the year

Agroforestry is an integration of tree species with agricultural crops or livestock that can be directly used to enhance agro biodiversity, rural livelihood and to meet the demand of green fodder throughout the year. Considering this fact, a study was done at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana to assess the productivity of fodder crops under poplar based agroforestry system. In February 2016, poplar was planted in six different spacing of 3× 3 m, 4×3 m, 5×3 m, 6×3 m, 7×3 m and 8×3 m. In this study, fodder crops (sorghum during Kharif season and oat and berseem during Rabi season) were intercropped in different spacing’s of poplar and compared with control in three replications. The results revealed that the maximum DBH (13.92 cm), basal diameter (16.90 cm) and crown spread (6.79 m) attained in 8×3 m spacing while maximum height (9.61 m) is attained in 3×3 m spacing. The highest pH (7.94) and EC (0.27 dS/m) were recorded in 8×3 m spacing while highest SOC (0.47 %), N (158.5 kg/ha), P (16.8 kg/ha) and K (343.8 kg/ha) were recorded in 3×3 m spacing. Green fodder biomass of sorghum (38.45 t/ha), berseem (64.56 t/ha) and oat (52.62 t/ha) was recorded higher in wider spacing (8×3 m) as compared to sole crops. The maximum light intensity (672.4 Lux) was recorded in 8×3 m at 1.00 pm in the month of July, 2018. Higher value of BCR was observed for poplar with oat (2.44) followed by poplar with sorghum (2.31) and poplar with berseem (2.28) under 3×3 m spacing indicating that closer spacing of 3×3 m of poplar is more economic than the other spacings due to more number of trees per unit area and more production of wood.

Fabrication of biodegradable films using &lt;sc&gt;l&lt;/sc&gt;-lactate as a chiral material to produce circularly polarized light

&lt;abstract&gt; &lt;p&gt;Optical activity and its relation to molecular chirality are significant in the measurement of optical rotation or circular dichroism characteristics to determine the absolute configuration of a chiral molecule. A quarter-wave plate, which is usually made from quartz, can convert linearly polarized light into circularly polarized light. In this study, we suggest using &lt;sc&gt;l&lt;/sc&gt;-lactic acid (&lt;sc&gt;l&lt;/sc&gt;-LA), a chiral material, and a water-based transparent glue to produce biodegradable films. Adjusting the number of thin layers, which are deposited from the mixture of &lt;sc&gt;l&lt;/sc&gt;-LA and polyvinyl alcohol, leads to different phase differences, forming &lt;sc&gt;l&lt;/sc&gt;-LA films. A modified microscope system was used to observe the appearance of the &lt;sc&gt;l&lt;/sc&gt;-LA wave plates. Six layers and 0.8% &lt;sc&gt;l&lt;/sc&gt;-LA solution were the optimal conditions to fabricate an &lt;sc&gt;l&lt;/sc&gt;-LA film. The circular polarization experiment showed that the changes in maximum and minimum light intensity were within 2% compared to the average light intensity at a specific angle of the &lt;sc&gt;l&lt;/sc&gt;-LA film. The performance of the &lt;sc&gt;l&lt;/sc&gt;-LA film was consistent with that of a commercial quarter-wave plate. In conclusion, circularly polarized light was successfully produced using the &lt;sc&gt;l&lt;/sc&gt;-LA film. The biodegradable &lt;sc&gt;l&lt;/sc&gt;-LA film has widespread application in the field of biomedicine. Featured Application: &lt;sc&gt;l&lt;/sc&gt;-Lactic acid film uses biodegradable and biocompatible materials. It can produce circularly polarized light and is beneficial for application in biomedicine.&lt;/p&gt; &lt;/abstract&gt;

Numerical study of self-focusing and filament formation of intense vortex beams in plasmas

We have studied the self-focusing and filamentation of vortex laser beams propagating in underdense plasmas with different values of the topological charge and initial laser powers. The self-focusing dynamics of vortex laser beams is closely related to the topological charge, which has attracted widespread attention. Based on the paraxial approximation of the Helmholtz equation, the steady-state solution of vortex beams propagating in underdense plasmas is deduced, and the expression for critical power of vortex laser beams is obtained. Furthermore, using the split-step Fourier method to solve the wave equation, we analyze the numerical images of vortex laser beams propagating in underdense plasma under different parameters. The simulation results show that the critical power for self-focusing is positively correlated with the topological charge of vortex laser beams. When the initial laser power is high enough, the vortex laser beam will first be focused into a thin ring, and then the modulation amplitude increases continuously, which eventually leads to the ring structure breaking into filaments. The number of filaments has an integer multiple relationship with the topological charge. In the process of filamentation, the radius and the maximum light intensity of vortex laser beam both change drastically. After the filamentation process is completed, the vortex laser beam continues to propagate with a new topological type. We further increase the incident laser power and find that the number of filaments of the vortex laser beam increases. The increased number of filaments is the value of its topological charge at each time. With the development of filament instability, higher-order modulation instability can be excited in the later stage, and the intensity of filaments will exhibit angular modulation. Our results show that in compared with the standard Gaussian beam, the propagation behavior of vortex laser beams in underdense plasmas is much more stable under the same power, wavelength and plasma parameters. The propagation characteristics of vortex laser beams are helpful to the theoretical and experimental study of stimulated backward Raman amplification of ultra-strong vortex beam in underdense plasmas.

MSLM-RF: A Spatial Feature Enhanced Random Forest for On-Board Hyperspectral Image Classification

Hyperspectral imaging (HSI) greatly improves the capacity to identify and monitor ground objects due to the high spectral resolution. As the real-time remote sensing monitoring and warning tasks are getting more attention, new algorithms for low-power on-board classification are required to reduce the transmission time of satellite downlink. In this paper, we propose the Multi-Scale Local Maximum Random Forest (MSLM-RF) to significantly reduce the energy consumption while retaining high classification accuracy. The proposed MSLM-RF uses multi-scale maximum filters for spatial feature extraction and Random Forest for classification after spectral and spatial features fusion. The spatial features are efficiently extracted with low computational complexity by regarding the maximum light intensity values in different ranges of pixels as anchor points. MSLM-RF only consists of integer comparisons and a few additions, thereby eliminating the energy-hungry operations such as multiplication and exponentiation. According to experimental results on the HSI benchmark datasets, MSLM-RF delivers a better trade-off in accuracy and computational complexity than the state-of-the-art classification algorithms. Besides, MSLM-RF gets higher average classification accuracy and lower energy consumption than the previous on-board algorithms. The obtained results show the suitability of the proposed algorithm to accomplish practical real-time classification tasks on-board with low energy consumption.

Optogenetic Stimulation of Gi Signaling Enables Instantaneous Modulation of Cardiomyocyte Pacemaking.

G-protein signaling pathways are central in the regulation of cardiac function in physiological and pathophysiological conditions. Their functional analysis through optogenetic techniques with selective expression of opsin proteins and activation by specific wavelengths allows high spatial and temporal precision. Here, we present the application of long wavelength-sensitive cone opsin (LWO) in cardiomyocytes for activation of the Gi signaling pathway by red light. Murine embryonic stem (ES) cells expressing LWO were generated and differentiated into beating cardiomyocytes in embryoid bodies (EBs). Illumination with red light (625 nm) led to an instantaneous decrease up to complete inhibition (84–99% effectivity) of spontaneous beating, but had no effect on control EBs. By using increasing light intensities with 10 s pulses, we determined a half maximal effective light intensity of 2.4 μW/mm2 and a maximum effect at 100 μW/mm2. Pre-incubation of LWO EBs with pertussis toxin completely inhibited the light effect proving the specificity for Gi signaling. Frequency reduction was mainly due to the activation of GIRK channels because the specific channel blocker tertiapin reduced the light effect by ~80%. Compared with pharmacological stimulation of M2 receptors with carbachol with slow kinetics (>30 s), illumination of LWO had an identical efficacy, but much faster kinetics (<1 s) in the activation and deactivation demonstrating the temporal advantage of optogenetic stimulation. Thus, LWO is an effective optogenetic tool for selective stimulation of the Gi signaling cascade in cardiomyocytes with red light, providing high temporal precision.

INVESTIGATION OF LIGHT INTENSITY OF LIGHT CURING UNITS AFTER DIFFERENT PERIODS OF USE

Quartz-tungsten halogen light curing units (LCUs) have been the main source of light for the polymerization of resin based composites (RBCs) for several decades. Since the beginning of the 20th century, however, their use has been reduced due to the invention and improvement of LED LCUs. Various factors can cause a decrease in the light intensity of LED LCUs, one of which is diode aging. The aim of the present paper is to study the change in light intensity of LCUs after different periods of intensive use. For this purpose, the light intensity of 94 regularly used LED LCUs aged between 1 and 10 years was measured with a digital radiometer. The devices were used in conventional mode with maximum light intensity. It was found that regardless of the type and model of LCU, there is a direct relationship between the time of use and light intensity - the longer the operation period of a device is and the more used it is, the lower its intensity is. The decrease in light intensity as devices age is different for different models, as well as for different devices of the same model. In the studied LCUs with a 10-year period of use, 77.5% have light intensity lower than the required minimum of 400 mW/cm2, which makes them unusable. It can be concluded that dentists should regularly monitor and measure the light intensity of their LCUs, especially as they age, to ensure the longevity of their restorative procedures.

DOONIES: A process-based ecogeomorphological functional community model for coastal dune vegetation and landscape dynamics

In ecogeomorphic systems, such as beach-dune habitats, complex couplings exist between geomorphology and ecology. Abiotic conditions influence vegetation growth and distribution while vegetation imposes a geomorphic feedback, impacting topography. Communities affect storm response by impacting pre-storm state, post-storm recovery, and landscape evolution. Despite their importance, beach-dune and other ecogeomorphic land-sea systems are deteriorating with increased anthropogenic modification and amplified natural disaster impact linked to climate change. A structured approach is needed to develop a more comprehensive understanding of coastal vegetation community interactions with the environment as these interactions underpin topographic change, strom response, and restoration and management efforts. Toward this goal, a spatially explicit process-based grid model, the DOONIES Model, encompassing biological, physiological, and geomorphological drivers of landscape change is presented. DOONIES simulates critical biotic and abiotic processes of vegetation growth, abundance, and spatial distribution dynamics impacting topography and storm response. Biological processes and ecogeomorphic responses are tailored to generalizable dune functional-communities with species-specific representatives. Estimates of the balance between photosynthesis and respiration dictate plant growth and morphology spatiotemporally which in turn impact sediment erosion and deposition. Relative sensitivity analyses indicate that the model is fundamentally driven by the photosynthesis formulation, where parameters such as maximum daily photosynthesis (grams of carbohydrate per day) and light intensity impact vegetation growth. These in turn, indirectly impact topographic change in modeled ecogeomorphic links. DOONIES is standalone and with a biological focus making it unique compared to more physical morphodynamic and hydrodynamic models with which this model is designed to couple. The model was evaluated by comparing simulation topography to actual across 6 years at Island Beach State Park, NJ while modeling Hurricane Sandy and daily wind conditions driving sediment input and output events. The predicted results were within the measurement error for the elevation datasets that the simulations were based on. This new model affords dynamic predictions of the response of naturally occurring and planted dune vegetation communities to typical abiotic conditions, as a tool for supporting and exploring restoration decisions.

Optical and Thermal Analysis of Secondary Optics in Light Emitting Diodes’ Packaging: Analysis of MR16 Lamp

Optical and thermal control are two main factors in package design process of lighting products, specifically light emitting diodes (LEDs). This research is aimed to study the role of secondary optics in opto-thermal characterization of LED packages. Novel thin total internal reflection (TIR) multifaceted reflector (MR) lens is modelled and optimized in Monte-Carlo ray-tracing simulations for MR16 package, regarded as one of the widely used LED lighting products. With criteria of designing an optical lens with 50% reduced thickness in comparison to commercially available lenses utilized in MR16 packages, nearly same light extraction efficiency and more uniform beam angles are achieved. Optical performance of the new lens is compared with the experimental results of the MR16 lamp with conventional lens. Only 2.3% reduction in maximum light intensity is obtained while lens size reduction was more than 25%. Based on the detailed CAD design, heat transfer simulations are performed comparing the lens thickness effect on heat dissipation of MR16 lamp. It was observed that using thinner lenses can reduce the lens and chip temperature, which can result in improved light quality and lifetime of both lens and light source.