Sowing depth and light intensity in the emergence and development of monocotyledonous weeds

This study aimed to evaluate the effects of different sowing depths and light intensities on the emergence and development of the monocot weed species, Urochloa decumbens and Cenchrus echinatus, under field conditions. Each species constituted an experiment, and the experimental design was completely randomized with four replicates. The treatments were arranged in a 6 x 4 factorial scheme, with six sowing depths (0.5, 1.0, 2.0, 4.0, 8.0, and 12.0 cm) associated with four solar radiation intensities (100%, 70%, 50%, and 30%) obtained through the use of shading screens. Seedling emergence capacity was evaluated daily to obtain the emergence percentage and speed index. Plant height, floral induction time, and plant dry matter at flowering were measured. Even when subjected to different solar radiation intensities, U. decumbens and C. echinatus seedlings emerged at all the sowing depths. Sowing between 2.0- and 4.0-cm depths favored the emergence of seedlings of U. decumbens and C. echinatus. However, sowing at 12-cm depth reduced the emergence of both species regardless of the solar radiation intensity. Urichloa decumbens plants grown under conditions of greater shading showed the lowest values of height and dry matter accumulation during flowering. High levels of shading facilitated only the etiolation of C. echinatus plants. Increased shading flowering time in both species compared to full sunlight.

A power law study of the edge influence on the perceived filling-in brightness magnitude

Abstract: Background: Edge plays a special role in spatial perception and as well as in determining the brightness of a surface within borders. The aim of our study was to measure threshold brightness in different levels of edges thickness. Methods: Steven's power law for circles modulating in luminance was estimated for 30 subjects (mean age 24 years, SD 3.3, 13 female). Stimuli were presented on the iMac display using the 11-bit graphic board and consisted of two circles of 3° of visual angle, separated by 10°. We tested 7 levels of Michelson contrast: 7, 8, 10, 15, 26, 50, and 100. Three edges filtering were tested (0.3, 0.8, and 1.5° of smoothing). The subjects' task was to judge the brightness of the edge filtered circle compared with the circle of the hard edge which was considered the modulus and received an arbitrary level of 50, representing the amount of brightness perception. In each trial, the same contrast level was presented in both circles. Five judgments were performed for each contrast level in edge filtering. Results: We found an increase in the power law exponent as the increase of the edge filtering (for sigma of 0.3 = 0.43, sigma of 0.8 = 0.73, and sigma 1.5 = 0.97). All power function fitting had high correlation coefficients (r2 = .94, r2 = .95, r2 = .97, respectively to sigma 0.3, 0.8, and 1.5) passing to the model's adhesion criteria. Conclusions: There was a progressive distortion on the figure brightness perception as increasing the edge filtering suggesting the control of edges on the polarity of the overall brightness. Also, perceived brightness was increasingly veridical with increased filtering, approaching 1:1 correspondence at 1.5 sigmas. (AU)

Differential Effect of Light Emitting Diode Light on Electroencephalographic Oscillations in Young and Old Healthy Subjects

OBJECTIVES: To investigate brain oscillatory characteristics according to brightness and color temperature of light emitting diode (LED) light in young and elderly subjects. METHODS: We analyzed 22 young (age, 29.0±5.2 years) and 23 elderly (age, 64.8±4.5 years) healthy subjects. A LED light source was used with a combination of two color temperature (6,500 K vs. 3,000 K) and two brightness (700 lx vs. 300 lx) conditions. Participants were exposed to each light condition in relaxed wakefulness. Then, we analyzed power spectral density and functional connectivity from eye-open electroencephalography. RESULTS: A main effect of brightness on delta (p=0.044) and theta (p=0.038) power was significant in the elderly subjects. Bright light enhanced delta and theta power in the frontal region. By contrast, power spectral density of young subjects was affected by color temperature; high color temperature significantly increased beta-band power of the central region (p=0.034). Regarding functional connectivity, a significant effect of color temperature was observed in delta (p=0.006) and beta (p=0.046) frequencies. High color temperature light enhanced beta connectivity of young subjects (p=0.007), while not affecting that of elderly subjects (p=0.979). CONCLUSIONS: The present study demonstrated that spectral power and functional connectivity as well as subjective feelings are affected by the brightness and color temperature of LED light. These results might help us to understand the neurophysiological effects of light and identify the optimal indoor lighting conditions for an individual's environment.

Application value of fluorescent intravenous indwelling catheter in dogs under different brightness conditions / 中国比较医学杂志

Objective To evaluate the clinical effectiveness of venipuncture using the fluorescent intravenous indwelling catheter in dark environment in dog experiments. Methods Six dogs were randomly divided into three groups of two dogs each, and each dog was subjected to 40 times of venipuncture performed on a foreleg with normal intravenous indwelling catheter and fluorescent intravenous indwelling catheter, respectively, under high(101 -105 lux), moderate (10.2-100 lux)or low(5 -10 lux)brightness conditions. The success rates and time consumption of those two procedures were analyzed and compared statistically. Results The success rate and time consumption for venipuncture using fluorescent and normal intravenous indwelling catheter under low brightness were 82.5% and(204.36 ± 13.13)s vs. 40.0% and(249.35 ± 17.98)s, those performed under moderate(simulating morning and dawn)brightness were 90.0% and(194.86 ± 8.60)s vs. 67.5% and(206.37 ± 9.70)s, all showed a significantly higher efficiency of the venipuncture using fluorescent intravenous indwelling catheter(P < 0.05). Conclusions The use of fluorescent intravenous indwelling catheter has the advantages of higher success rate and shorter time consumption for venipuncture under low and moderate brightness conditions.

Functional vision barriers: a new concept analyzed in terms of human visual performance

In this work we introduce a new category of barriers that we call "functional vision barriers." This expression refers to lighting and visual elements that may complicate or hinder functional vision and may make life even more difficult for people with visual defects. These barriers appear as a consequence of certain negative effects caused by the poor design of the visual stimulus or visual environment that surrounds it in which lighting is one of the main factors. We use the term "functional vision" because this expression refers to the ability of the visual system to perform everyday tasks. We analyzed some of our previous results with regard to situations that can be considered "functional vision barriers": (1) stimuli with low luminance contrast information in which the addition of chromatic contrast improves visual performance and (2) tasks that are performed in the presence of a glare source in the visual field, diminishing visual performance and reducing brightness perception...

Effects of Color Temperature and Brightness on Electroencephalogram Alpha Activity in a Polychromatic Light-emitting Diode

OBJECTIVE: It has been reported that working and learning efficiency might be increased through artificially controlling the color temperature and brightness of light. However, the neurological bases of these outcomes are not well established. Our study was designed to observe whether electroencephalogram (EEG) alpha frequency, as a candidate biological marker, demonstrates significant changes in response to alterations of specific light parameters. METHODS: Thirty-two healthy subjects performed cognitive tasks under four different polychromatic light conditions: a combination of two different levels of color temperature (2766K vs. 5918K) and brightness (300 lux vs. 600 lux). Spectrum analyses were performed on alpha frequency. RESULTS: Subjects reported that they felt more pleasant in bright conditions and more relaxed in warm color temperature conditions. Our findings indicate that alpha power increases in warm, low-light and cool, high-light conditions, and there is a significant interaction between color temperature and brightness. CONCLUSION: EEGs might serve as a useful biological marker for further research related to the effects of polychromatic light on cognitive function.

Simple luminosity normalization of greenness, yellowness and redness/greenness for comparison of leaf spectral profiles in multi-temporally acquired remote sensing images.

Observation of leaf colour (spectral profiles) through remote sensing is an effective method of identifying the spatial distribution patterns of abnormalities in leaf colour, which enables appropriate plant management measures to be taken. However, because the brightness of remote sensing images varies with acquisition time, in the observation of leaf spectral profiles in multi-temporally acquired remote sensing images, changes in brightness must be taken into account. This study identified a simple luminosity normalization technique that enables leaf colours to be compared in remote sensing images over time. The intensity values of green and yellow (green+red) exhibited strong linear relationships with luminosity (R2>0.926) when various invariant rooftops in Bangkok or Tokyo were spectralprofiled using remote sensing images acquired at different time points. The values of the coefficient and constant or the coefficient of the formulae describing the intensity of green or yellow were comparable among the single Bangkok site and the two Tokyo sites, indicating the technique’s general applicability. For single rooftops, the values of the coefficient of variation for green, yellow, and red/green were 16% or less (n=6−11), indicating an accuracy not less than those of well-established remote sensing measures such as the normalized difference vegetation index. After obtaining the above linear relationships, raw intensity values were normalized and a temporal comparison of the spectral profiles of the canopies of evergreen and deciduous tree species in Tokyo was made to highlight the changes in the canopies’ spectral profiles. Future aspects of this technique are discussed herein.

Comparison of tooth crown discoloration with Epiphany and AH26 sealer in terms of chroma and value: an in vitro study

Tooth crown discoloration may possess a heavy emotional burden and esthetic concern, especially when the anterior teeth are affected. Residue of sealers within the pulp chamber is a major contributor to the occurrence of tooth discoloration. Aim: The aim of this study was to evaluate the degree of crown discoloration when recently introduced sealer, Epiphany, is used. Methods: Forty human incisors were examined in vitro. Fifteen teeth were sealed with either AH26 or Epiphany sealer as experimental groups and root canals of the remaining 10 teeth with distilled water. Digital photographs of the buccal aspect of teeth were then examined in terms of brightness (value) and saturation (chroma) using Photoshop software at the beginning and consecutive 3, 6 and 9 months. Degree of brightness and saturation changes was defined as follows: less than 5% as slight, 10% to 15% as moderate and 15% to 20% as severe. Results: Fifteen, 14 and 10 teeth entered in Epiphany, AH26 and control groups, respectively. Significant brightness deterioration was noticed by time in both experimental groups [F (2, 8) =29.16, p<0.001], with no differences in Epiphany compared with AH26 (p=0.086). Saturation differed neither by time [F (2, 8) =0.129, p=0.881, nor by sealer type (p=0.136) during 9-month observation. At 9th month, crown segments (incisal, middle and cervical thirds) were not contrasted by the sealer type (p=0.982) or discoloration type (either brightness or saturation) (p=0.50). All changes in the experimental groups were significantly higher than the control group (p<0.001). Conclusions: Epiphany was equal to AH26 sealer in terms of relative long-term crown discoloration. One clinical correlation learned from the results of the present study is that Epiphany may safely be used interchangeably with the traditional AH26 sealer.

Monitor selection of imaging diagnostic workstation configuration for PACS / 医疗卫生装备

With growing dependence on picture archiving and communication systems(PACS) for viewing images,a quality assurance program to the condition of workstation displays and image quality guidelines for better cost-efficacy and diagnostic accuracy has become increasingly important.This article analyses and synthesizes the quality control of the PACS phantom workstation mainly from such aspects as the monitor resolution and brightness,the environment degree of illumination,statistics assessment method(ROC curve) and so on.