Modeling Dynamic Laser Speckle Patterns of Plant Leaves

2013 ◽  
Vol 694-697 ◽  
pp. 1363-1367 ◽  
Author(s):  
Xu Zhong ◽  
Xue Zhi Wang ◽  
Peter Farrell ◽  
Nicola Cooley ◽  
Bill Moran
Keyword(s):  
Leaf Surface ◽  
Temporal Evolution ◽  
Water Status ◽  
Sample Surface ◽  
Laser Speckle ◽  
Plant Leaves ◽  
Electromagnetic Wave Scattering ◽  
Dynamic Speckle ◽  
Speckle Patterns ◽  
The Relationship

t is known that dynamic speckle patterns can be used to identify the temporal evolution of an active sample and some desired properties of the sample may therefore be detected via the dynamic laser speckle analysis. Mathematically understand the structure of sample surface which gives arise to the dynamic speckle patterns is crucial to the analysis. In this paper, a simulation model of the dynamic speckle patterns for plant leaves is proposed. The developed model is derived from the principle of coherent electromagnetic wave scattering off a randomly textured and time varying surface and is demonstrated via the simulation of dynamic speckle patterns of a fresh unattached leaf surface along the true laser speckle measurements. Both simulated and true measurements of the dynamic speckle patterns of the leaf are analyzed via several statistical techniques and a consistent agreement between the results of the two is observed. The proposed statistical model is helpful to gain the insight of the relationship between speckle dynamics and the activity of the leaf surface which is supposed to be an measurement of plant water stress and water status.

scholarly journals Preoperative endothelial dysfunction in cutaneous microcirculation is associated with postoperative organ injury after cardiac surgery using extracorporeal circulation: a prospective cohort study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Stanislas Abrard ◽  
Olivier Fouquet ◽  
Jérémie Riou ◽  
Emmanuel Rineau ◽  
Pierre Abraham ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Cohort Study ◽  
Endothelial Dysfunction ◽  
Postoperative Complications ◽  
Sofa Score ◽  
Primary Objective ◽  
Laser Speckle ◽  
Organ Injury ◽  
Contrast Imaging ◽  
The Relationship

Abstract Background Cardiac surgery is known to induce acute endothelial dysfunction, which may be central to the pathophysiology of postoperative complications. Preoperative endothelial dysfunction could also be implicated in the pathophysiology of postoperative complications after cardiac surgery. However, the relationship between preoperative endothelial function and postoperative outcomes remains unknown. The primary objective was to describe the relationship between a preoperative microcirculatory dysfunction identified by iontophoresis of acetylcholine (ACh), and postoperative organ injury in patients scheduled for cardiac surgery using cardiopulmonary bypass (CPB). Methods Sixty patients undergoing elective cardiac surgery using CPB were included in the analysis of a prospective, observational, single-center cohort study conducted from January to April 2019. Preoperative microcirculation was assessed with reactivity tests on the forearm (iontophoresis of ACh and nitroprusside). Skin blood flow was measured by laser speckle contrast imaging. Postoperative organ injury, the primary outcome, was defined as a Sequential Organ Failure Assessment score (SOFA) 48 h after surgery greater than 3. Results Organ injury at 48 h occurred in 29 cases (48.3%). Patients with postoperative organ injury (SOFA score > 3 at 48 h) had a longer time to reach the peak of preoperative iontophoresis of acetylcholine (133 s [104–156] vs 98 s [76–139] than patients without, P = 0.016), whereas endothelium-independent vasodilation to nitroprusside was similar in both groups. Beyond the proposed threshold of 105 s for time to reach the peak of preoperative endothelium-dependent vasodilation, three times more patients presented organ dysfunction at 48 h (76% vs 24% below or equal 105 s). In multivariable model, the time to reach the peak during iontophoresis of acetylcholine was an independent predictor of postoperative organ injury (odds ratio = 4.81, 95% confidence interval [1.16–19.94]; P = 0.030). Conclusions Patients who postoperatively developed organ injury (SOFA score > 3 at 48 h) had preoperatively a longer time to reach the peak of endothelium-dependent vasodilation. Trial registration Clinical-Trials.gov, NCT03631797. Registered 15 August 2018, https://clinicaltrials.gov/ct2/show/NCT03631797

CORRELATION BETWEEN ELECTRIC CHARGING OF THE SAMPLE SURFACE AND KINETICS OF OPTICALLY STIMULATED EXOELECTRON EMISSION (OSEE) FROM CRYOSOLIDIFIED NaCl SOLUTION

1990 ◽  
Vol 04 (03) ◽  
pp. 201-209
Author(s):  
A. GIEROSZYŃSKI
Keyword(s):  
Electric Fields ◽  
Surface Potential ◽  
Surface Region ◽  
Sample Surface ◽  
Exoelectron Emission ◽  
Nacl Solution ◽  
Emitter Surface ◽  
Emitter Layer ◽  
The Relationship ◽  
Kinetics Of

It was found that OSEE kinetics from electron bombarded cryosolidified NaCl solution, depend on electric charging of the sample surface. It was shown that from the relationship between the maximum surface potential and the parameters of OSEE kinetic, intensities of electric fields in the emitter layer could be estimated. It is supposed that nonhomogeneous electric fields existing in the emitter surface region, influence the emission levels responsible for the course of OSEE kinetics.

scholarly journals Fourier transforms for fast and quantitative Laser Speckle Imaging

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Buijs ◽  
J. van der Gucht ◽  
J. Sprakel
Keyword(s):  
Quantitative Data ◽  
Fourier Transforms ◽  
Imaging Technique ◽  
Laser Speckle ◽  
Frequency Range ◽  
Laser Speckle Imaging ◽  
Speckle Imaging ◽  
New Approach ◽  
Speckle Patterns ◽  
New Processing

Abstract Laser speckle imaging is a powerful imaging technique that visualizes microscopic motion within turbid materials. At current two methods are widely used to analyze speckle data: one is fast but qualitative, the other quantitative but computationally expensive. We have developed a new processing algorithm based on the fast Fourier transform, which converts raw speckle patterns into maps of microscopic motion and is both fast and quantitative, providing a dynamnic spectrum of the material over a frequency range spanning several decades. In this article we show how to apply this algorithm and how to measure a diffusion coefficient with it. We show that this method is quantitative and several orders of magnitude faster than the existing quantitative method. Finally we harness the potential of this new approach by constructing a portable laser speckle imaging setup that performs quantitative data processing in real-time on a tablet.

scholarly journals The Relationship Between Cloud Cover and Outgoing Longwave Radiation in the Southern of Vietnam

2018 ◽  
Vol 34 (1S) ◽  
Author(s):  
Chu Thi Thu Huong ◽  
Bui Thi Hop ◽  
Tran Dinh Linh ◽  
Vu Thanh Hang
Keyword(s):  
Spatial Distribution ◽  
Rainy Season ◽  
Outgoing Longwave Radiation ◽  
Cloud Cover ◽  
Temporal Evolution ◽  
El Nino ◽  
Longwave Radiation ◽  
Downward Trend ◽  
La Nina ◽  
The Relationship

Abstract: Based on the data that has the resolution is 1,00×1,00of the Outgoing Longwave Radiation (OLR) and the cloud cover from NCEP/NCAR in the 1981 – 2012 period, the relationship between the cloud cover and the OLR in the Southern of Vietnam wasinvestigated when analyze and compare the spatial distribution, temporal evolution and their correlation. The results show that the characteristics of the spatial distribution and the year cycle of cloud cover and OLR are inversely correlated. The region or time that the cloud cover is great, the OLR is small and vice versa. In the Southern of Vietnam, the OLR value isgreatest(or smallest) in the dry (or rainy) season and in the El-Nino (La-Nina) years. In addition, during the 1981-2012period, the OLR in this region shows a downward trend about 3.6 W/m2/decade, while the cloud cover tends to increase by 0.2%/decade. Keywords: Cloud cover, Outgoing Longwave Radiation, the Southern of Vietnam.

scholarly journals Remotely Sensed Water Limitation in Vegetation: Insights from an Experiment with Unmanned Aerial Vehicles (UAVs)

2019 ◽  
Author(s):  
Kelly Easterday ◽  
Chippie Kislik ◽  
Tod E. Dawson ◽  
Sean Hogan ◽  
Maggi Kelly
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Water Content ◽  
Water Deficit ◽  
Water Status ◽  
Field Measurements ◽  
Flying Height ◽  
Plant Water ◽  
Spectral Indices ◽  
Aerial Vehicles ◽  
The Relationship

Unmanned aerial vehicles (UAVs) equipped with multispectral sensors present an opportunity to monitor vegetation with on-demand high spatial and temporal resolution. In this study, we use multispectral imagery from quadcopter UAVs to monitor the progression of a water manipulation experiment on a common shrub, Baccharis pilularis (coyote brush), at the Blue Oak Ranch Reserve (BORR) near San Jose, California. We recorded multispectral data from the plants at several altitudes with nearly hourly intervals to explore the relationship between two common spectral indices, NDVI and NDRE, and plant water content and water potential, as physiological metrics of plant water status, across a gradient of water deficit. An examination of the spatial and temporal thresholds at which water limitations were most detectable revealed that the best separation between levels of water deficit were at higher resolution (lower flying height), and in the morning (NDVI) and early morning (NDRE). We found that both measures were able to identify moisture deficit in plants and distinguish them from control and watered plants; however, NDVI was better able to distinguish between treatments than NDRE and was more positively correlated with field measurements of plant water content than NDRE. Finally, we explored how relationships between spectral indices and water status changed when the imagery was scaled to courser resolutions provided by satellite-based imagery (PlanetScope) and found that PlanetScope data was able to capture the overall trend in treatments but was not able to capture subtle changes in water content. These kinds of experiments that evaluate the relationship between direct field measurements and UAV camera sensitivity are needed to enable translation of field-based physiology measurements to landscape or regional scales.

scholarly journals Thermal Imaging Reliability for Estimating Grain Yield and Carbon Isotope Discrimination in Wheat Genotypes: Importance of the Environmental Conditions

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2676 ◽  
Author(s):  
Sebastián Romero-Bravo ◽  
Ana María Méndez-Espinoza ◽  
Miguel Garriga ◽  
Félix Estrada ◽  
Alejandro Escobar ◽  
...  
Keyword(s):  
Grain Yield ◽  
Thermal Imaging ◽  
Mediterranean Climate ◽  
Vapor Pressure Deficit ◽  
Stress Condition ◽  
Water Status ◽  
Canopy Temperature ◽  
Spring Bread Wheat ◽  
Wheat Genotypes ◽  
The Relationship

Canopy temperature (Tc) by thermal imaging is a useful tool to study plant water status and estimate other crop traits. This work seeks to estimate grain yield (GY) and carbon discrimination (Δ13C) from stress degree day (SDD = Tc − air temperature, Ta), considering the effect of a number of environmental variables such as the averages of the maximum vapor pressure deficit (VPDmax) and the ambient temperature (Tmax), and the soil water content (SWC). For this, a set of 384 and a subset of 16 genotypes of spring bread wheat were evaluated in two Mediterranean-climate sites under water stress (WS) and full irrigation (FI) conditions, in 2011 and 2012, and 2014 and 2015, respectively. The relationship between the GY of the 384 wheat genotypes and SDD was negative and highly significant in 2011 (r2 = 0.52 to 0.68), but not significant in 2012 (r2 = 0.03 to 0.12). Under WS, the average GY, Δ13C, and SDD of wheat genotypes growing in ten environments were more associated with changes in VPDmax and Tmax than with the SWC. Therefore, the amount of water available to the plant is not enough information to assume that a particular genotype is experiencing a stress condition.

scholarly journals Measuring the Water Content in Wood Using Step-Heating Thermography and Speckle Patterns-Preliminary Results

Sensors ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 316 ◽  
Author(s):  
Francisco J. Madruga ◽  
Stefano Sfarra ◽  
Stefano Perilli ◽  
Elena Pivarčiová ◽  
José M. López-Higuera
Keyword(s):  
Speckle Interferometry ◽  
Thermophysical Parameters ◽  
Step Heating ◽  
Speckle Patterns ◽  
Experimental Values ◽  
The One ◽  
The Relationship ◽  
Fundamental Values ◽  
Integrated Study ◽  
Water Contents

The relationship between wood and its degree of humidity is one of the most important aspects of its use in construction and restoration. The wood presents a behavior similar to a sponge, therefore, moisture is related to its expansion and contraction. The nondestructive evaluation (NDE) of the amount of moisture in wood materials allows to define, e.g., the restoration procedures of buildings or artworks. In this work, an integrated study of two non-contact techniques is presented. Infrared thermography (IRT) was able to retrieve thermal parameters of the wood related to the amount of water added to the samples, while the interference pattern generated by speckles was used to quantify the expansion and contraction of wood that can be related to the amount of water. In twenty-seven wooded samples, a known quantity of water was added in a controlled manner. By applying advanced image processing to thermograms and specklegrams, it was possible to determine fundamental values controlling both the absorption of water and the main thermophysical parameters that link the samples. On the one hand, results here shown should be considered preliminary because the experimental values obtained by IRT need to be optimized for low water contents introduced into the samples. On the other hand, speckle interferometry by applying an innovative procedure provided robust results for both high and low water contents.

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