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Sample records for red spectral edge

  1. Red edge spectral measurements from sugar maple leaves

    NASA Technical Reports Server (NTRS)

    Vogelmann, J. E.; Rock, B. N.; Moss, D. M.

    1993-01-01

    Many sugar maple stands in the northeastern United States experienced extensive insect damage during the 1988 growing season. Chlorophyll data and high spectral resolution spectrometer laboratory reflectance data were acquired for multiple collections of single detached sugar maple leaves variously affected by the insect over the 1988 growing season. Reflectance data indicated consistent and diagnostic differences in the red edge portion (680-750 nm) of the spectrum among the various samples and populations of leaves. These included differences in the red edge inflection point (REIP), a ratio of reflectance at 740-720 nm (RE3/RE2), and a ratio of first derivative values at 715-705 nm (D715/D705). All three red edge parameters were highly correlated with variation in total chlorophyll content. Other spectral measures, including the Normalized Difference Vegetation Index (NDVI) and the Simple Vegetation Index Ratio (VI), also varied among populations and over the growing season, but did not correlate well with total chlorophyll content. Leaf stacking studies on light and dark backgrounds indicated REIP, RE3/RE2 and D715/D705 to be much less influenced by differences in green leaf biomass and background condition than either NDVI or VI.

  2. SENTINEL-2A red-edge spectral indices suitability for discriminating burn severity

    NASA Astrophysics Data System (ADS)

    Fernández-Manso, Alfonso; Fernández-Manso, Oscar; Quintano, Carmen

    2016-08-01

    Fires are a problematic and recurrent issue in Mediterranean ecosystems. Accurate discrimination between burn severity levels is essential for the rehabilitation planning of burned areas. Sentinel-2A MultiSpectral Instrument (MSI) record data in three red-edge wavelengths, spectral domain especially useful on agriculture and vegetation applications. Our objective is to find out whether Sentinel-2A MSI red-edge wavelengths are suitable for burn severity discrimination. As study area, we used the 2015 Sierra Gata wildfire (Spain) that burned approximately 80 km2. A Copernicus Emergency Management Service (EMS)-grading map with four burn severity levels was considered as reference truth. Cox and Snell, Nagelkerke and McFadde pseudo-R2 statistics obtained by Multinomial Logistic Regression showed the superiority of red-edge spectral indices (particularly, Modified Simple Ratio Red-edge, Chlorophyll Index Red-edge, Normalized Difference Vegetation Index Red-edge) over conventional spectral indices. Fisher's Least Significant Difference test confirmed that Sentinel-2A MSI red-edge spectral indices are adequate to discriminate four burn severity levels.

  3. Vegetation Red-edge Spectral Modeling for Solar-induced Chlorophyll Fluorescence Retrieval at O2-B Band

    NASA Astrophysics Data System (ADS)

    Huang, C.; Zhang, L.; Qiao, N.; Zhang, X.; Li, Y.

    2015-12-01

    Remotely sensed solar-induced chlorophyll fluorescence (SIF) has been considered an ideal probe in monitoring global vegetation photosynthesis. However, challenges in accurate estimate of faint SIF (less than 5% of the total reflected radiation in near infrared bands) from the observed apparent reflected radiation greatly limit its wide applications. Currently, the telluric O2-B (~688nm) and O2-A (~761nm) have been proved to be capable of SIF retrieval based on Fraunhofer line depth (FLD) principle. They may still work well even using conventional ground-based commercial spectrometers with typical spectral resolutions of 2~5 nm and high enough signal-to-noise ratio (e.g., the ASD spectrometer). Nevertheless, almost all current FLD based algorithms were mainly developed for O2-A, a few concentrating on the other SIF emission peak in O2-B. One of the critical reasons is that it is very difficult to model the sudden varying reflectance around O2-B band located in the red-edge spectral region (about 680-800 nm). This study investigates a new method by combining the established inverted Gaussian reflectance model (IGM) and FLD principle using diurnal canopy spectra with relative low spectral resolutions of 1 nm (FluorMOD simulations) and 3 nm (measured by ASD spectrometer) respectively. The IGM has been reported to be an objective and good method to characterize the entire vegetation red-edge reflectance. Consequently, the proposed SIF retrieval method (hereinafter called IGMFLD) could exploit all the spectral information along the whole red-edge (680-800 nm) to obtain more reasonable reflectance and fluorescence correction coefficients than traditional FLD methods such as the iFLD. Initial results show that the IGMFLD can better capture the spectrally non-linear characterization of the reflectance in 680-800 nm and thereby yields much more accurate SIFs in O2-B than typical FLD methods, including sFLD, 3FLD and iFLD (see figure 1). Finally, uncertainties and prospect

  4. Unravelling remote sensing signatures of plants contaminated with gasoline and diesel: an approach using the red edge spectral feature.

    PubMed

    Sanches, I D; Souza Filho, C R; Magalhães, L A; Quitério, G C M; Alves, M N; Oliveira, W J

    2013-03-01

    Pipeline systems used to transport petroleum products represent a potential source of soil pollution worldwide. The design of new techniques that may improve current monitoring of pipeline leakage is imperative. This paper assesses the remote detection of small leakages of liquid hydrocarbons indirectly, through the analysis of spectral features of contaminated plants. Leaf and canopy spectra of healthy plants were compared to spectra of plants contaminated with diesel and gasoline, at increasing rates of soil contamination. Contamination effects were observed both visually in the field and thorough changes in the spectral reflectance patterns of vegetation. Results indicate that the remote detection of small volumes of gasoline and diesel contaminations is feasible based on the red edge analysis of leaf and canopy spectra of plants. Brachiaria grass ranks as a favourable choice to be used as an indicator of HCs leakages along pipelines. PMID:23246622

  5. Red-Edge Spectral Reflectance as an Indicator of Surface Moisture Content in an Alaskan Peatland Ecosystem

    NASA Astrophysics Data System (ADS)

    McPartland, M.; Kane, E. S.; Turetsky, M. R.; Douglass, T.; Falkowski, M. J.; Montgomery, R.; Edwards, J.

    2015-12-01

    Arctic and boreal peatlands serve as major reservoirs of terrestrial organic carbon (C) because Net Primary Productivity (NPP) outstrips C loss from decomposition over long periods of time. Peatland productivity varies as a function of water table position and surface moisture content, making C storage in these systems particularly vulnerable to the climate warming and drying predicted for high latitudes. Detailed spatial knowledge of how aboveground vegetation communities respond to changes in hydrology would allow for ecosystem response to environmental change to be measured at the landscape scale. This study leverages remotely sensed data along with field measurements taken at the Alaska Peatland Experiment (APEX) at the Bonanza Creek Long Term Ecological Research site to examine relationships between plant solar reflectance and surface moisture. APEX is a decade-long experiment investigating the effects of hydrologic change on peatland ecosystems using water table manipulation treatments (raised, lowered, and control). Water table levels were manipulated throughout the 2015 growing season, resulting in a maximum separation of 35 cm between raised and lowered treatment plots. Water table position, soil moisture content, depth to seasonal ice, soil temperature, photosynthetically active radiation (PAR), CO2 and CH4 fluxes were measured as predictors of C loss through decomposition and NPP. Vegetation was surveyed for percent cover of plant functional types. Remote sensing data was collected during peak growing season, when the separation between treatment plots was at maximum difference. Imagery was acquired via a SenseFly eBee airborne platform equipped with a Canon S110 red-edge camera capable of detecting spectral reflectance from plant tissue at 715 nm band center to within centimeters of spatial resolution. Here, we investigate empirical relationships between spectral reflectance, water table position, and surface moisture in relation to peat carbon balance.

  6. Benefits of Red-Edge Spectral Band and Texture Features for the Object-based Classification using RapidEye sSatellite Image data

    NASA Astrophysics Data System (ADS)

    Kim, H. O.; Yeom, J. M.

    2014-12-01

    Space-based remote sensing in agriculture is particularly relevant to issues such as global climate change, food security, and precision agriculture. Recent satellite missions have opened up new perspectives by offering high spatial resolution, various spectral properties, and fast revisit rates to the same regions. Here, we examine the utility of broadband red-edge spectral information in multispectral satellite image data for classifying paddy rice crops in South Korea. Additionally, we examine how object-based spectral features affect the classification of paddy rice growth stages. For the analysis, two seasons of RapidEye satellite image data were used. The results showed that the broadband red-edge information slightly improved the classification accuracy of the crop condition in heterogeneous paddy rice crop environments, particularly when single-season image data were used. This positive effect appeared to be offset by the multi-temporal image data. Additional texture information brought only a minor improvement or a slight decline, although it is well known to be advantageous for object-based classification in general. We conclude that broadband red-edge information derived from conventional multispectral satellite data has the potential to improve space-based crop monitoring. Because the positive or negative effects of texture features for object-based crop classification could barely be interpreted, the relationships between the textual properties and paddy rice crop parameters at the field scale should be further examined in depth.

  7. Comparing Broad-Band and Red Edge-Based Spectral Vegetation Indices to Estimate Nitrogen Concentration of Crops Using Casi Data

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Liao, Qinhong; Yang, Guijun; Feng, Haikuan; Yang, Xiaodong; Yue, Jibo

    2016-06-01

    In recent decades, many spectral vegetation indices (SVIs) have been proposed to estimate the leaf nitrogen concentration (LNC) of crops. However, most of these indices were based on the field hyperspectral reflectance. To test whether they can be used in aerial remote platform effectively, in this work a comparison of the sensitivity between several broad-band and red edge-based SVIs to LNC is investigated over different crop types. By using data from experimental LNC values over 4 different crop types and image data acquired using the Compact Airborne Spectrographic Imager (CASI) sensor, the extensive dataset allowed us to evaluate broad-band and red edge-based SVIs. The result indicated that NDVI performed the best among the selected SVIs while red edge-based SVIs didn't show the potential for estimating the LNC based on the CASI data due to the spectral resolution. In order to search for the optimal SVIs, the band combination algorithm has been used in this work. The best linear correlation against the experimental LNC dataset was obtained by combining the 626.20nm and 569.00nm wavebands. These wavelengths correspond to the maximal chlorophyll absorption and reflection position region, respectively, and are known to be sensitive to the physiological status of the plant. Then this linear relationship was applied to the CASI image for generating an LNC map, which can guide farmers in the accurate application of their N fertilization strategies.

  8. The red edge of plant leaf reflectance

    NASA Technical Reports Server (NTRS)

    Horler, D. N. H.; Dockray, M.; Barber, J.

    1983-01-01

    A detailed study of the red edge spectral feature of green vegetation based on laboratory reflectance spectrophotometry is presented. A parameter lambda is defined as the wavelength is defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration. Species, development stage, leaf layering, and leaf water content of vegetation also influences lambda. The maximum slope parameter is found to be independent of simulated ground area coverage. The results are interpreted in terms of Beer's Law and Kubelka-Munk theory. The chlorophyll concentration dependence of lambda seems to be explained in terms of a pure absorption effect, and it is suggested that the existence of two lambda components arises from leaf scattering properties. The results indicate that red edge measurements will be valuable for assessment of vegetative chlorophyll status and leaf area index independently of ground cover variations, and will be particularly suitable for early stress detection.

  9. Red edge measurements for remotely sensing plant chlorophyll content

    NASA Technical Reports Server (NTRS)

    Horler, D. N. H.; Dockray, M.; Barber, J.; Barringer, A. R.

    1983-01-01

    The feasibility of using the wavelength of the maximum slope of the red edge of leaf reflectance spectra, Lambda(re), as an indication of plant chlorophyll status was examined in the laboratory for single leaves of several species. Lambda(re) for each sample was determined by derivative reflectance spectroscopy. A high positive correlation was found between Lambda(re) and leaf chlorophyll content for all species, although there were some differences in the quantitative nature of the relationship for plants of different types. The position of the red edge was found to be unaffected by simulated change in ground cover, but multiple leaf layers produced a shift in its position. Appropriate spectral measurements and processing for obtaining useful information from the red edge are discussed, and the potential of the red edge in relation to other spectral measurements is considered.

  10. The Red Edge Problem in asteroid band parameter analysis

    NASA Astrophysics Data System (ADS)

    Lindsay, Sean S.; Dunn, Tasha L.; Emery, Joshua P.; Bowles, Neil E.

    2016-04-01

    Near-infrared reflectance spectra of S-type asteroids contain two absorptions at 1 and 2 μm (band I and II) that are diagnostic of mineralogy. A parameterization of these two bands is frequently employed to determine the mineralogy of S(IV) asteroids through the use of ordinary chondrite calibration equations that link the mineralogy to band parameters. The most widely used calibration study uses a Band II terminal wavelength point (red edge) at 2.50 μm. However, due to the limitations of the NIR detectors on prominent telescopes used in asteroid research, spectral data for asteroids are typically only reliable out to 2.45 μm. We refer to this discrepancy as "The Red Edge Problem." In this report, we evaluate the associated errors for measured band area ratios (BAR = Area BII/BI) and calculated relative abundance measurements. We find that the Red Edge Problem is often not the dominant source of error for the observationally limited red edge set at 2.45 μm, but it frequently is for a red edge set at 2.40 μm. The error, however, is one sided and therefore systematic. As such, we provide equations to adjust measured BARs to values with a different red edge definition. We also provide new ol/(ol+px) calibration equations for red edges set at 2.40 and 2.45 μm.

  11. Vegetation's red edge: a possible spectroscopic biosignature of extraterrestrial plants.

    PubMed

    Seager, S; Turner, E L; Schafer, J; Ford, E B

    2005-06-01

    Earth's deciduous plants have a sharp order-of-magnitude increase in leaf reflectance between approximately 700 and 750 nm wavelength. This strong reflectance of Earth's vegetation suggests that surface biosignatures with sharp spectral features might be detectable in the spectrum of scattered light from a spatially unresolved extrasolar terrestrial planet. We assess the potential of Earth's step-function-like spectroscopic feature, referred to as the "red edge," as a tool for astrobiology. We review the basic characteristics and physical origin of the red edge and summarize its use in astronomy: early spectroscopic efforts to search for vegetation on Mars and recent reports of detection of the red edge in the spectrum of Earthshine (i.e., the spatially integrated scattered light spectrum of Earth). We present Earthshine observations from Apache Point Observatory (New Mexico) to emphasize that time variability is key to detecting weak surface biosignatures such as the vegetation red edge. We briefly discuss the evolutionary advantages of vegetation's red edge reflectance, and speculate that while extraterrestrial "light-harvesting organisms" have no compelling reason to display the exact same red edge feature as terrestrial vegetation, they might have similar spectroscopic features at different wavelengths than terrestrial vegetation. This implies that future terrestrial-planet-characterizing space missions should obtain data that allow time-varying, sharp spectral features at unknown wavelengths to be identified. We caution that some mineral reflectance edges are similar in slope and strength to vegetation's red edge (albeit at different wavelengths); if an extrasolar planet reflectance edge is detected care must be taken with its interpretation. PMID:15941381

  12. On the Red Edge an Optical Biomarker for Detecting Extrateresstrial Plants

    NASA Astrophysics Data System (ADS)

    Ford, E. B.; Seager, S.; Turner, E. L.

    2005-12-01

    Earth's deciduous plants have a sharp order-of-magnitude increase in leaf reflectance between approximately 700 and 750 nm wavelength. This strong reflectance of Earth's vegetation suggests that surface biosignatures with sharp spectral features might be detectable in the spectrum of scattered light from a spatially unresolved extrasolar terrestrial planet. We assess the potential of Earth's step-function-like spectroscopic feature, referred to as the ``red edge,'' as a tool for astrobiology. First, we review the basic characteristics and physical origin of the red edge. Then, we discuss the challenges involved in detecting the red edge in Earthshine (i.e., a spatially integrated scattered light spectrum of the Earth), as evidenced by recent attempts to detect the red edge using spectroscopic observations of the dark side of the moon (which is illuminated by Eartshine). We present Earthshine observations from Apache Point Observatory (New Mexico) to emphasize that time variability is key to detecting weak surface biosignatures such as the vegetation red edge. We briefly discuss the evolutionary advantages of vegetation's red edge reflectance, and speculate that while extraterrestrial ``light-harvesting organisms'' have no compelling reason to display the exact same red edge feature as terrestrial vegetation, they might have similar spectroscopic features at different wavelengths than terrestrial vegetation. This implies that future terrestrial-planet characterizing space missions should obtain data that allow time-varying, sharp spectral features at unknown wavelengths to be identified. We caution that some mineral reflectance edges are similar in slope and strength to vegetation's red edge (albeit at different wavelengths). Due to the small amplitude of the terrestrial red edge, the temporal variability of atmospheric water vapor, and the potential for similar mineralogical features, we conclude that great care must be taken in the interpretation of any

  13. Evaluating the impact of red-edge band from Rapideye image for classifying insect defoliation levels

    NASA Astrophysics Data System (ADS)

    Adelabu, Samuel; Mutanga, Onisimo; Adam, Elhadi

    2014-09-01

    The prospect of regular assessments of insect defoliation using remote sensing technologies has increased in recent years through advances in the understanding of the spectral reflectance properties of vegetation. The aim of the present study was to evaluate the ability of the red edge channel of Rapideye imagery to discriminate different levels of insect defoliation in an African savanna by comparing the results of obtained from two classifiers. Random Forest and Support vector machine classification algorithms were applied using different sets of spectral analysis involving the red edge band. Results show that the integration of information from red edge increases classification accuracy of insect defoliation levels in all analysis performed in the study. For instance, when all the 5 bands of Rapideye imagery were used for classification, the overall accuracies increases about 19% and 21% for SVM and RF, respectively, as opposed to when the red edge channel was excluded. We also found out that the normalized difference red-edge index yielded a better accuracy result than normalized difference vegetation index. We conclude that the red-edge channel of relatively affordable and readily available high-resolution multispectral satellite data such as Rapideye has the potential to considerably improve insect defoliation classification especially in sub-Saharan Africa where data availability is limited.

  14. The effect of a red leaf pigment on the relationship between red edge and chlorophyll concentration

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Macler, Bruce A.; Plummer, Stephen E.

    1991-01-01

    The effect of a leaf pigment - red amaranthin - on red edge and chlorophyll concentration is investigated in amaranth leaves by means of treatments with nitrate and salts. A near-linear relationship between red edge and chlorophyll concentration is observed for leaves with low amaranthin concentration, and no relationship is noted at high concentrations. The study demonstrates the limitation inherent in estimating chlorophyll concentration by using remotely sensed red edge.

  15. Spectral Tuning of Deep Red Cone Pigments†

    PubMed Central

    Amora, Tabitha L.; Ramos, Lavoisier S.; Galan, Jhenny F.; Birge, Robert R.

    2008-01-01

    Visual pigments are G-protein-coupled receptors that provide a critical interface between organisms and their external environment. Natural selection has generated vertebrate pigments that absorb light from the far-UV (360 nm) to the deep red (630 nm) while using a single chromophore, in either the A1 (11-cis-retinal) or A2 (11-cis-3,4-dehydroretinal) form. The fact that a single chromophore can be manipulated to have an absorption maximum across such an extended spectral region is remarkable. The mechanisms of wavelength regulation remain to be fully revealed, and one of the least well-understood mechanisms is that associated with the deep red pigments. We investigate theoretically the hypothesis that deep red cone pigments select a 6-s-trans conformation of the retinal chromophore ring geometry. This conformation is in contrast to the 6-s-cis ring geometry observed in rhodopsin and, through model chromophore studies, the vast majority of visual pigments. Nomographic spectral analysis of 294 A1 and A2 cone pigment literature absorption maxima indicates that the selection of a 6-s-trans geometry red shifts M/LWS A1 pigments by ~1500 cm−1 (~50 nm) and A2 pigments by ~2700 cm−1 (~100 nm). The homology models of seven cone pigments indicate that the deep red cone pigments select 6-s-trans chromophore conformations primarily via electrostatic steering. Our results reveal that the generation of a 6-s-trans conformation not only achieves a significant red shift but also provides enhanced stability of the chromophore within the deep red cone pigment binding sites. PMID:18370404

  16. An asymmetric BODIPY triad with panchromatic absorption for high-performance red-edge laser emission.

    PubMed

    Duran-Sampedro, Gonzalo; Agarrabeitia, Antonia R; Garcia-Moreno, Inmaculada; Gartzia-Rivero, Leire; de la Moya, Santiago; Bañuelos, Jorge; López-Arbeloa, Íñigo; Ortiz, María J

    2015-07-21

    A rational design of an unprecedented asymmetric cassette triad based entirely on BODIPY chromophores allows efficient light harvesting over the UV-vis spectral region, leading to a bright and stable red-edge laser emission via efficient energy-transfer processes. PMID:26084606

  17. Exploring the Relationship Between Reflectance Red Edge and Chlorophyll Content in Slash Pine

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Gholz, Henry L.

    1990-01-01

    Chlorophyll is a key indicator of the physiological status of a forest canopy. However, its distribution may vary greatly in time and space, so that the estimation of chlorophyll content of canopies or branches by extrapolation from leaf values obtained by destructive sampling is labor intensive and potentially inaccurate. Chlorophy11 content is related positively to the point of maximum slope in vegetation reflectance spectra which occurs at wavelengths between 690-740 nm and is known as the "red edge." The red edge of needles on individual slash pine (Piniis elliottii Engelm.) branches and in whole forest canopies was measured with a spectroradiometer. Branches were measured on the ground against a spectrally flat reflectance target and canopies were measured from observation towers against a spectrally variable understory and forest floor. There was a linear relationship between red edge and chlorophyll content of branches (R(exp 2) = 0.91). Measurements of the red edge and this relationship were used to estimate the chlorophyll content of other branches with an error that was lower than that associated with the colorimetric (laboratory) method. There was no relationship between the red edge and the chlorophyll content of whole canopies. This can be explained by the overriding influence of the understory and forest floor, an influence that was illustrated by spectral mixture modeling. The results suggest that the red edge could be used to estimate the chlorophyll content in branches but it is unlikely to be of value for the estimation of chlorophyll content in canopies unless the canopy cover is high.

  18. Dependence of red edge on eddy viscosity model parameters

    NASA Technical Reports Server (NTRS)

    Deupree, R. G.; Cole, P. W.

    1980-01-01

    The dependence of the red edge location on the two fundamental free parameters in the eddy viscosity treatment was extensively studied. It is found that the convective flux is rather insensitive to any reasonable or allowed value of the two free parameters of the treatment. This must be due in part to the fact that the convective flux is determined more by the properties of the hydrogen ionization region than by differences in convective structure. The changes in the effective temperature of the red edge of the RR Lyrae gap resulting from these parameter variations is quite small (approximately 150 K). This is true both because the parameter variation causes only small changes and because large changes in the convective flux are required to produce any significant change in red edge location. The possible changes found are substantially less than the approximately 600 K required to change the predicted helium abundance mass fraction from 0.3 to 0.2.

  19. [Using extraction of red edge position to validate consistency of hyperspectral imaging and non-imaging data].

    PubMed

    Wang, Da-Cheng; Zhang, Dong-Yan; Zhao, Jin-Ling; Li, Cun-Jun; Zhu, Da-Zhou; Huang, Wen-Jiang; Li, Yu-Fei; Yang, Xiao-Dong

    2011-09-01

    Using Pushbroom imaging spectrometer (PIS) and FieldSpec ProFR2500 (ASD), spectral reflectances of winter wheat and maize at different stages were collected synchronously. In order to validate the reliability of imaging spectral data, the red edge position of hyperspectral data for PIS and ASD were extracted by different algorithms, respectively. The following results were obtained: (1) The original spectrum of both instruments had high inosculation in red light region (670-740 nm); (2) With the spectra collected under laboratory condition (maize leaf), the extracted red edge position was is concentrated between 700 and 720 nm for the two instruments; (3) With the spectra collected undre field condition (wheat leaf), the extracted red edge position for PIS and ASD were different, the red edge position of PIS data was in 760 nm, while it was in 720 nm for ASD data. The main reason might be that the imaging spectral data were influenced by oxygen absorbtion; (4) the red edge rangeability of PIS and ASD were different, but the trends were the same. The above results could provide some references for hyperspectral imaging data's extensive application. PMID:22097847

  20. Solvent reorganizational red-edge effect in intramolecular electron transfer.

    PubMed Central

    Demchenko, A P; Sytnik, A I

    1991-01-01

    Polar solvents are characterized by statistical distributions of solute-solvent interaction energies that result in inhomogeneous broadening of the solute electronic spectra. This allows photoselection of the high interaction energy part of the distribution by excitation at the red (long-wavelength) edge of the absorption bands. We observe that intramolecular electron transfer in the bianthryl molecule from the locally excited (LE) to the charge-transfer (CT) state, which requires solvent relaxation and does not occur in vitrified polar solutions, is dramatically facilitated in low-temperature propylene glycol glass by the red-edge excitation. This allows one to obtain spectroscopically the pure CT form and observe its dependence upon the relaxational properties of the solvent. A qualitative potential model of this effect is presented. PMID:11607224

  1. Spectral Information Retrieval for Sub-Pixel Building Edge Detection

    NASA Astrophysics Data System (ADS)

    Avbelj, J.

    2012-07-01

    Building extraction from imagery has been an active research area for decades. However, the precise building detection from hyperspectral (HSI) images solely is a less often addressed research question due to the low spatial resolution of data. The building boundaries are usually represented by spectrally mixed pixels, and classical edge detector algorithms fail to detect borders with sufficient completeness. The idea of the proposed method is to use fraction of materials in mixed pixels to derive weights for adjusting building boundaries. The building regions are detected using seeded region growing and merging in a HSI image; for the initial seed point selection the digital surface model (DSM) is used. Prior to region growing, the seeds are statistically tested for outliers on the basis of their spectral characteristics. Then, the border pixels of building regions are compared in spectrum to the seed points by calculating spectral dissimilarity. From this spectral dissimilarity the weights for weighted and constrained least squares (LS) adjustment are derived. We used the Spectral Angle Mapper (SAM) for spectral similarity measure, but the proposed boundary estimation method could benefit from soft classification or spectral unmixing results. The method was tested on a HSI image with spatial resolution of 4 m, and buildings of rectangular shape. The importance of constraints to the relations between building parts, e.g. perpendicularity is shown on example with a building with inner yards. The adjusted building boundaries are compared to the laser DSM, and have a relative accuracy of boundaries 1/4 of a pixel.

  2. Identification and Spectral Classification of Close Red Dwarf Binary Stars

    NASA Astrophysics Data System (ADS)

    Chivers, James

    2015-01-01

    The position angle, angular and linear separation, distance, and spectral class of 713 red dwarf binary star systems are reported based on data-mining the Sloan Digital Sky Survey Data Release 10. 707 of these systems are new discoveries.

  3. Spectral characteristics analysis of red tide water in mesocosm experiment

    NASA Astrophysics Data System (ADS)

    Cui, Tingwei; Zhang, Jie; Zhang, Hongliang; Ma, Yi; Gao, Xuemin

    2003-05-01

    Mesocosm ecosystem experiment with seawater enclosed of the red tide was carried out from July to September 2001. We got four species of biology whose quantities of bion are dominant in the red tide. During the whole process from the beginning to their dying out for every specie, in situ spectral measurements were carried out. After data processing, characteristic spectra of red tide of different dominant species are got. Via comparison and analysis of characteristics of different spectra, we find that in the band region between 685 and 735 nanometers, spectral characteristics of red tide is apparently different from that of normal water. Compared to spectra of normal water, spectra of red tide have a strong reflectance peak in the above band region. As to spectra of red tide dominated by different species, the situations of reflectance peaks are also different: the second peak of Mesodinium rubrum spectrum lies between 726~732 nm, which is more than 21nm away from the other dominant species spectra"s Leptocylindrus danicus"s second spectral peak covers 686~694nm; that of Skeletonema costatum lies between 691~693 nm. Chattonella marina"s second spectral peak lies about 703~705 nm. Thus we can try to determine whether red tide has occurred according to its spectral data. In order to monitor the event of red tide and identify the dominant species by the application of the technology of hyperspectral remote sensing, acquiring spectral data of different dominant species of red tide as much as possible becomes a basic work to be achieved for spectral matching, information extraction and so on based on hyperspectral data.

  4. Spectral CT using multiple balanced K-edge filters.

    PubMed

    Rakvongthai, Yothin; Worstell, William; El Fakhri, Georges; Bian, Junguo; Lorsakul, Auranuch; Ouyang, Jinsong

    2015-03-01

    Our goal is to validate a spectral computed tomography (CT) system design that uses a conventional X-ray source with multiple balanced K-edge filters. By performing a simultaneously synthetic reconstruction in multiple energy bins, we obtained a good agreement between measurements and model expectations for a reasonably complex phantom. We performed simulation and data acquisition on a phantom containing multiple rods of different materials using a NeuroLogica CT scanner. Five balanced K-edge filters including Molybdenum, Cerium, Dysprosium, Erbium, and Tungsten were used separately proximal to the X-ray tube. For each sinogram bin, measured filtered vector can be defined as a product of a transmission matrix, which is determined by the filters and is independent of the imaging object, and energy-binned intensity vector. The energy-binned sinograms were then obtained by inverting the transmission matrix followed by a multiplication of the filter measurement vector. For each energy bin defined by two consecutive K-edges, a synthesized energy-binned attenuation image was obtained using filtered back-projection reconstruction. The reconstructed attenuation coefficients for each rod obtained from the experiment was in good agreement with the corresponding simulated results. Furthermore, the reconstructed attenuation coefficients for a given energy bin, agreed with National Institute of Standards and Technology reference values when beam hardening within the energy bin is small. The proposed cost-effective system design using multiple balanced K-edge filters can be used to perform spectral CT imaging at clinically relevant flux rates using conventional detectors and integrating electronics. PMID:25252276

  5. Spectral CT Using Multiple Balanced K-Edge Filters

    PubMed Central

    Rakvongthai, Yothin; Worstell, William; Fakhri, Georges El; Bian, Junguo; Lorsakul, Auranuch; Ouyang, Jinsong

    2015-01-01

    Our goal is to validate a spectral CT system design that uses a conventional X-ray source with multiple balanced K-edge filters. By performing a simultaneously synthetic reconstruction in multiple energy bins, we obtained a good agreement between measurements and model expectations for a reasonably complex phantom. We performed simulation and data acquisition on a phantom containing multiple rods of different materials using a NeuroLogica CT scanner. Five balanced K-edge filters including Molybdenum, Cerium, Dysprosium, Erbium, and Tungsten were used separately proximal to the X-ray tube. For each sinogram bin, measured filtered vector can be defined as a product of a transmission matrix, which is determined by the filters and is independent of the imaging object, and energy-binned intensity vector. The energy-binned sinograms were then obtained by inverting the transmission matrix followed by a multiplication of the filter measurement vector. For each energy bin defined by two consecutive K-edges, a synthesized energy-binned attenuation image was obtained using filtered back-projection reconstruction. The reconstructed attenuation coefficients for each rod obtained from the experiment was in good agreement with the corresponding simulated results. Furthermore, the reconstructed attenuation coefficients for a given energy bin, agreed with National Institute of Standards and Technology reference values when beam hardening within the energy bin is small. The proposed cost-effective system design using multiple balanced K-edge filters can be used to perform spectral CT imaging at clinically relevant flux rates using conventional detectors and integrating electronics. PMID:25252276

  6. The red edge in arid region vegetation: 340-1060 nm spectra

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Murray, Bruce C.; Chehbouni, A.; Njoku, Eni

    1993-01-01

    The remote sensing study of vegetated regions of the world has typically been focused on the use of broad-band vegetation indices such as NDVI. Various modifications of these indices have been developed in attempts to minimize the effect of soil background, e.g., SAVI, or to reduce the effect of the atmosphere, e.g., ARVI. Most of these indices depend on the so-called 'red edge,' the sharp transition between the strong absorption of chlorophyll pigment in visible wavelengths and the strong scattering in the near-infrared from the cellular structure of leaves. These broadband indices tend to become highly inaccurate as the green canopy cover becomes sparse. The advent of high spectral resolution remote sensing instrument such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) has allowed the detection of narrow spectral features in vegetation and there are reports of detection of the red edge even for pixels with very low levels of green vegetation cover by Vane et al. and Elvidge et al., and to characterize algal biomass in coastal areas. Spectral mixing approaches similar to those of Smith et al. can be extended into the high spectral resolution domain allowing for the analysis of more endmembers, and potentially, discrimination between material with narrow spectral differences. Vegetation in arid regions tends to be sparse, often with small leaves such as the creosote bush. Many types of arid region vegetation spend much of the year with their leaves in a senescent state, i.e., yellow, with lowered chlorophyll pigmentation. The sparseness of the leaves of many arid region plants has the dual effect of lowering the green leaf area which can be observed and of allowing more of the sub-shrub soil to be visible which further complicates the spectrum of a region covered with arid region vegetation. Elvidge examined the spectral characteristics of dry plant materials showing significant differences in the region of the red edge and the diagnostic ligno

  7. Stimulated Emission of Active Media in the Red Spectral Range

    NASA Astrophysics Data System (ADS)

    Kopylova, T. N.; Gadirov, R. M.; Nikonov, S. Yu.; Valiev, R. R.; Tel'minov, E. N.; Nikonova, E. N.; Solodova, T. A.; Alekseeva, V. I.; Marinina, L. E.; Savvina, L. P.

    2016-05-01

    Spectral, luminescent, and lasing characteristics of chromene dyes and their julolidine analogs emitting in the red spectral range are investigated experimentally and theoretically. It is shown that the cause for a low lasing efficiency of oxochromene compared with iminochromene is a high intersystem crossing to the T 1 state and the presence of the induced T 1→T n absorption in the region of the luminescence band.

  8. [Using the distance between hyperspectral red edge position and yellow edge position to identify wheat yellow rust disease].

    PubMed

    Jiang, Jin-Bao; Chen, Yun-Hao; Huang, Wen-Jiang

    2010-06-01

    The objective of the present paper is to identify healthy wheat and disease wheat by using hyeprspectral remote sensing as soon as possible. The canopy spectral reflectance of winter wheat infected by different severity yellow rust was measured and the disease indices (DI) were investigated in the field respectively. Smoothing the canopy spectra and calculating the first derivative values, the two methods were used to calculate the red edge position (REP) and yellow edge position (YEP) of the first derivative values: (a) maximum of the first derivative value; (b) Cho and Skidmore method. The result showed that REP gradually shifted to short-wave band, and the YEP gradually shifted to long-wave band with disease severity increasing, however, REP-YEP quickly became smaller. Analyzing and comparing the prediction precision of REP, YEP and REP-YEP for DI, the result indicated that the model REP-YEP as variable has the best estimation precision for DI than REP and YEP, the model estimation error is 6.22, and relative error is 14.3%, and it could identify healthy and disease wheat 12 days before the disease symptom apparently appeared. Therefore, this study not only can provide theory and technology for large areas monitoring of wheat disease by using hyperspectral remote sensing in the future, but also has the important meaning and practical application value for implementing precision agriculture. PMID:20707161

  9. Estimating fresh grass/herb biomass from HYMAP data using the red edge position

    NASA Astrophysics Data System (ADS)

    Cho, Moses A.; Sobhan, Istiak M.; Skidmore, Andrew K.

    2006-08-01

    Remote sensing of grass/herb quantity is essential for rangeland management of livestock and wildlife. Spectral indices such as NDVI, determined from red and near infrared bands are affected by variable soil and atmospheric conditions and saturate in dense vegetation. Alternatively, the wavelength of maximum slope in the red-NIR transition, termed the red edge position (REP) has potential to mitigate these effects. But the utility of the REP using air- and space-borne imagery is determined by the availability of narrow bands in the region of the red edge and the simplicity of the extraction method. Very recently, we proposed a simple technique for extracting the REP called the linear extrapolation method [Cho and Skidmore, Remote Sens. Environ., 101(2006)118.]. The purpose of this study was to evaluate the potential of the linear extrapolation method for estimating fresh grass/herb biomass and compare its performance with the four-point linear interpolation and three-point Lagrangian interpolation methods. The REPs were derived from atmospherically corrected HYMAP images collected over Majella National Park, Italy in July 2004. The predictive capabilities of various REP linear regression models were evaluated using leave-one-out cross validation and test set validation methods. For both validation methods, the linear extrapolation REP models produced higher correlations with grass/herb biomass and lower prediction errors compared with the linear interpolation and Lagrangian REP models. This study demonstrates the potential of REPs extracted by the linear extrapolation method using HYMAP data for estimating fresh grass/herb biomass.

  10. NIMS Spectral Maps of Jupiter's Great Red Spot

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Near-Infrared Mapping Spectrometer (NIMS) instrument looks at Jupiter's Great Red Spot, in these views from June 26, 1996. NIMS studies infrared wavelengths of light that our eye cannot see. These maps are at four different infrared wavelengths, each one picked to reveal something different about the atmosphere.

    The top image is a false color map of a wavelength that is at the red edge of our ability to see. It shows the shapes of features that we would see with our eyes.

    The second map is of ammonia ice, red showing where the most ice is, blue where none exists. The differences between this and the first image are due to the amount and size of ammonia ice crystals.

    The third map down is from a wavelength that shows cloud heights, with the highest clouds in red, and the lowest in blue.

    The bottom map uses a wavelength that shows the hot Jupiter shining through the clouds. Red represents the thinnest clouds, and blue is thickest where it is more difficult to see below. Comparing the bottom two images, note that the highest clouds are in the center of the Great Red Spot, while there are relatively few clouds around the edges.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  11. Spectral comparison and stability of red regions on Jupiter

    NASA Astrophysics Data System (ADS)

    Simon, Amy A.; Sanchez-Lavega, Agustin; Legarreta, Jon; Francisco Sanz-Requena, Jose; Perez-Hoyos, Santiago; Garcia-Melendo, Enrique; Carlson, Robert W.

    2015-03-01

    A rare red cyclone visible on Jupiter in 1994 and 1995 falls in a class of vortices that are intensely colored, yet low altitude, unlike the Great Red Spot (GRS). Dynamical modeling indicates that the presence of nearby anticyclones both aids in formation and lead to the destruction of the cyclone. A study of absolute spectral reflectance from Hubble Space Telescope imaging data shows that GRS is not typically the "reddest" region of the planet. Rather, transient red cyclones and the reddest parts of the North Equatorial Belt show less reflectance than the GRS at all wavelengths, with enhanced absorption at wavelengths near 500 nm. Temporal analysis shows that the darkest regions of the North Equatorial Belt and transient red cyclones are relatively constant in color from 1995 to 2014, while the spectral slope and absolute brightness of the GRS core vary over time. Laboratory data of colored materials that yield a good qualitative fit to the GRS spectrum do not match the spectra of other regions, and wavelengths from 400 to 700 nm may be most diagnostic of chromophore identification.

  12. Dynamic insight into protein structure utilizing red edge excitation shift.

    PubMed

    Chattopadhyay, Amitabha; Haldar, Sourav

    2014-01-21

    Proteins are considered the workhorses in the cellular machinery. They are often organized in a highly ordered conformation in the crowded cellular environment. These conformations display characteristic dynamics over a range of time scales. An emerging consensus is that protein function is critically dependent on its dynamics. The subtle interplay between structure and dynamics is a hallmark of protein organization and is essential for its function. Depending on the environmental context, proteins can adopt a range of conformations such as native, molten globule, unfolded (denatured), and misfolded states. Although protein crystallography is a well established technique, it is not always possible to characterize various protein conformations by X-ray crystallography due to transient nature of these states. Even in cases where structural characterization is possible, the information obtained lacks dynamic component, which is needed to understand protein function. In this overall scenario, approaches that reveal information on protein dynamics are much appreciated. Dynamics of confined water has interesting implications in protein folding. Interfacial hydration combines the motion of water molecules with the slow moving protein molecules. The red edge excitation shift (REES) approach becomes relevant in this context. REES is defined as the shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of absorption spectrum. REES arises due to slow rates (relative to fluorescence lifetime) of solvent relaxation (reorientation) around an excited state fluorophore in organized assemblies such as proteins. Consequently, REES depends on the environment-induced motional restriction imposed on the solvent molecules in the immediate vicinity of the fluorophore. In the case of a protein, the confined water in the protein creates a dipolar field that acts as the solvent for a fluorophore

  13. Sensitivity of Sentinel-2 Red-Edge Bands to Leaf Chlorophyll Concentration in Winter Wheat

    NASA Astrophysics Data System (ADS)

    Vincini, Massimo; Amaducci, Stefano; Frazzi, Ermes

    2012-04-01

    The present work addresses the comparison between the sensitivity of several narrow-band and broad-band vegetation indices (VI) to leaf chlorophyll concentration at the canopy scale in winter wheat field trials with different nitrogen fertilization levels. Spectral signatures were collected on three dates (Feekes growth stages 5-6-9) over experimental plots with a portable spectroradiometer (ASD FieldSpec HH), along with Minolta SPAD measures of leaf optical thickness as a proxy of leaf chlorophyll concentration. Considered broad-band indices included classical slope-based VI (i.e.: NDVI, SR and OSAVI) and some indices incorporating green reflectance (i.e. Green NDVI, Green SR, CVI and MTVI), whereas narrow-band indices included VI specifically proposed as leaf chlorophyll estimators at the canopy scale (i.e. MCARI/OSAVI, TCARI/OSAVI, TCI/OSAVI, NOAC, REIP and MTCI). Broad-band VI were obtained from average reflectance in spectral ranges corresponding to SPOT HRG bands and from average reflectance in Sentinel-2 visible and NIR bands whereas narrow-band VI were obtained from reflectance at the original spectral resolution of the spectroradiometer and from average reflectance in Sentinel-2 Red-Edge bands. Among VI obtained from Sentinel-2 bands REIP and MTCI indices were the best narrow-band estimators of winter wheat leaf chlorophyll concentration, whereas CVI was the best estimator among broad-band VI.

  14. Joint spatio-spectral based edge detection for multispectral infrared imagery.

    SciTech Connect

    Krishna, Sanjay; Hayat, Majeed M.; Bender, Steven C.; Sharma, Yagya D.; Jang, Woo-Yong; Paskalva, Biliana S.

    2010-06-01

    Image segmentation is one of the most important and difficult tasks in digital image processing. It represents a key stage of automated image analysis and interpretation. Segmentation algorithms for gray-scale images utilize basic properties of intensity values such as discontinuity and similarity. However, it is possible to enhance edge-detection capability by means of using spectral information provided by multispectral (MS) or hyperspectral (HS) imagery. In this paper we consider image segmentation algorithms for multispectral images with particular emphasis on detection of multi-color or multispectral edges. More specifically, we report on an algorithm for joint spatio-spectral (JSS) edge detection. By joint we mean simultaneous utilization of spatial and spectral characteristics of a given MS or HS image. The JSS-based edge-detection approach, termed Spectral Ratio Contrast (SRC) edge-detection algorithm, utilizes the novel concept of matching edge signatures. The edge signature represents a combination of spectral ratios calculated using bands that enhance the spectral contrast between the two materials. In conjunction with a spatial mask, the edge signature give rise to a multispectral operator that can be viewed as a three-dimensional extension of the mask. In the extended mask, the third (spectral) dimension of each hyper-pixel can be chosen independently. The SRC is verified using MS and HS imagery from a quantum-dot in a well infrared (IR) focal plane array, and the Airborne Hyperspectral Imager.

  15. Evaluation of Sentinel-2 Red-Edge Bands for Empirical Estimation of Green LAI and Chlorophyll Content

    PubMed Central

    Delegido, Jesús; Verrelst, Jochem; Alonso, Luis; Moreno, José

    2011-01-01

    ESA’s upcoming satellite Sentinel-2 will provide Earth images of high spatial, spectral and temporal resolution and aims to ensure continuity for Landsat and SPOT observations. In comparison to the latter sensors, Sentinel-2 incorporates three new spectral bands in the red-edge region, which are centered at 705, 740 and 783 nm. This study addresses the importance of these new bands for the retrieval and monitoring of two important biophysical parameters: green leaf area index (LAI) and chlorophyll content (Ch). With data from several ESA field campaigns over agricultural sites (SPARC, AgriSAR, CEFLES2) we have evaluated the efficacy of two empirical methods that specifically make use of the new Sentinel-2 bands. First, it was shown that LAI can be derived from a generic normalized difference index (NDI) using hyperspectral data, with 674 nm with 712 nm as best performing bands. These bands are positioned closely to the Sentinel-2 B4 (665 nm) and the new red-edge B5 (705 nm) band. The method has been applied to simulated Sentinel-2 data. The resulting green LAI map was validated against field data of various crop types, thereby spanning a LAI between 0 and 6, and yielded a RMSE of 0.6. Second, the recently developed “Normalized Area Over reflectance Curve” (NAOC), an index that derives Ch from hyperspectral data, was studied on its compatibility with simulated Sentinel-2 data. This index integrates the reflectance curve between 643 and 795 nm, thereby including the new Sentinel-2 bands in the red-edge region. We found that these new bands significantly improve the accuracy of Ch estimation. Both methods emphasize the importance of red-edge bands for operational estimation of biophysical parameters from Sentinel-2. PMID:22164004

  16. Evaluation of Sentinel-2 red-edge bands for empirical estimation of green LAI and chlorophyll content.

    PubMed

    Delegido, Jesús; Verrelst, Jochem; Alonso, Luis; Moreno, José

    2011-01-01

    ESA's upcoming satellite Sentinel-2 will provide Earth images of high spatial, spectral and temporal resolution and aims to ensure continuity for Landsat and SPOT observations. In comparison to the latter sensors, Sentinel-2 incorporates three new spectral bands in the red-edge region, which are centered at 705, 740 and 783 nm. This study addresses the importance of these new bands for the retrieval and monitoring of two important biophysical parameters: green leaf area index (LAI) and chlorophyll content (Ch). With data from several ESA field campaigns over agricultural sites (SPARC, AgriSAR, CEFLES2) we have evaluated the efficacy of two empirical methods that specifically make use of the new Sentinel-2 bands. First, it was shown that LAI can be derived from a generic normalized difference index (NDI) using hyperspectral data, with 674 nm with 712 nm as best performing bands. These bands are positioned closely to the Sentinel-2 B4 (665 nm) and the new red-edge B5 (705 nm) band. The method has been applied to simulated Sentinel-2 data. The resulting green LAI map was validated against field data of various crop types, thereby spanning a LAI between 0 and 6, and yielded a RMSE of 0.6. Second, the recently developed "Normalized Area Over reflectance Curve" (NAOC), an index that derives Ch from hyperspectral data, was studied on its compatibility with simulated Sentinel-2 data. This index integrates the reflectance curve between 643 and 795 nm, thereby including the new Sentinel-2 bands in the red-edge region. We found that these new bands significantly improve the accuracy of Ch estimation. Both methods emphasize the importance of red-edge bands for operational estimation of biophysical parameters from Sentinel-2. PMID:22164004

  17. Stabilization of Polar Step Edges on Calcite (10.4) by the Adsorption of Congo Red.

    PubMed

    Momper, Rebecca; Nalbach, Martin; Lichtenstein, Karin; Bechstein, Ralf; Kühnle, Angelika

    2015-07-01

    In this work, we present the stabilization of polar step edges along the [010] direction of calcite (10.4) by the presence of a water-soluble organic molecule, namely Congo Red. While characteristic etch pits are observed on the surface in the absence of the additive, no etch pits can be found in the presence of the additive. Using atomic force microscopy, we can directly follow the restructuring of the surface. Upon addition of Congo Red, the charge-neutral step edges confining the characteristic etch pits vanish, while polar step edges along the [010] direction appear on the surface, which are entirely decorated by well-ordered molecular islands of the additive. After the restructuring has taken place, the surface exclusively exhibits these polar step edges. Our results give direct evidence of the fact that these polar step edges become thermodynamically favored when Congo Red is present. PMID:26053526

  18. Regional estimation of savanna grass nitrogen using the red-edge band of the spaceborne RapidEye sensor

    NASA Astrophysics Data System (ADS)

    Ramoelo, A.; Skidmore, A. K.; Cho, M. A.; Schlerf, M.; Mathieu, R.; Heitkönig, I. M. A.

    2012-10-01

    The regional mapping of grass nutrients is of interest in the sustainable planning and management of livestock and wildlife grazing. The objective of this study was to estimate and map foliar and canopy nitrogen (N) at a regional scale using a recent high resolution spaceborne multispectral sensor (i.e. RapidEye) in the Kruger National Park (KNP) and its surrounding areas, South Africa. The RapidEye sensor contains five spectral bands in the visible-to-near infrared (VNIR), including a red-edge band centered at 710 nm. The importance of the red-edge band for estimating foliar chlorophyll and N concentrations has been demonstrated in many previous studies, mostly using field spectroscopy. The utility of the red-edge band of the RapidEye sensor for estimating grass N was investigated in this study. A two-step approach was adopted involving (i) vegetation indices and (ii) the integration of vegetation indices with environmental or ancillary variables using a stepwise multiple linear regression (SMLR) and a non-linear spatial least squares regression (PLSR). The model involving the simple ratio (SR) index (R805/R710) defined as SR54, altitude and the interaction between SR54 and altitude (SR54 * altitude) yielded the highest accuracy for canopy N estimation, while the non-linear PLSR yielded the highest accuracy for foliar N estimation through the integration of remote sensing (SR54) and environmental variables. The study demonstrated the possibility to map grass nutrients at a regional scale provided there is a spaceborne sensor encompassing the red edge waveband with a high spatial resolution.

  19. Edge detection of red hind grouper vocalizations in the littorals

    NASA Astrophysics Data System (ADS)

    Matthews, Cameron A.; Beaujean, Pierre-Philippe

    2016-05-01

    Littoral regions typically present to passive sensors as a high noise acoustic environment, particularly with respect to port and harbor regions where tidal variation, often characterized as pink, mixes with reverberation from on-shore business and commercial shipping, often characterized as white. Some fish in these regions, in particular epiphenalius Guttatus or more commonly the red hind grouper, emit relatively narrowband tones in low frequencies to communicate with other fish in such regions. The impact of anthropogenic noise sources on the red Hind and other fish is a topical area of interest for wildlife fisheries, private sportsmen and military offices that is not considered here; the fact that fish species continue to populate and communicate in these regions in the presence of high noise content lends some study to the signal content and modeling of a potential biologically inspired receiver structure.

  20. Spectral Comparison and Stability of Red Regions on Jupiter

    NASA Technical Reports Server (NTRS)

    Simon, A. A.; Carlson, R. W.; Sanchez-Lavega, A.

    2013-01-01

    A study of absolute color on Jupiter from Hubble Space Telescope imaging data shows that the Great Red Spot (GRS) is not the reddest region of the planet. Rather, a transient red cyclone visible in 1995 and the North Equatorial Belt both show redder spectra than the GRS (i.e., more absorption at blue and green wavelengths). This cyclone is unique among vortices in that it is intensely colored yet low altitude, unlike the GRS. Temporal analysis shows that the darkest regions of the NEB are relative constant in color from 1995 to 2008, while the slope of the GRS core may vary slightly. Principal component analysis shows several spectral components are needed, in agreement with past work, and further highlights the differences between regions. These color differences may be indicative of the same chromophore(s) under different conditions, such as mixing with white clouds, longer UV irradiation at higher altitude, and thermal processing, or may indicate abundance variations in colored compounds. A single compound does not fit the spectrum of any region well and mixes of multiple compounds including NH4SH, photolyzed NH3, hydrocarbons, and possibly P4, are likely needed to fully match each spectrum.

  1. Angular and spectral distribution of infrared synchrotron radiation emitted by an undulator and its edges

    NASA Astrophysics Data System (ADS)

    Nucara, Alessandro; Cestelli Guidi, Mariangela; Marcouille, Oliver; Roy, Pascale; Calvani, Paolo; Giura, P.; Paolone, A.; Mathis, Yves-Laurent

    1999-10-01

    Both the angular and the spectral distribution of the Infrared Synchrotron Radiation emitted by an undulator of Super-ACO have been measured. Structures due to undulator edges, as well as contributions from the edge emission of a bending magnet placed behind the undulator, have been observed. Detailed calculations including all these sources are in excellent agreement with the measurements, provided that both velocity and acceleration terms are considered.

  2. Edge effects in graphene nanostructures: Semiclassical theory of spectral fluctuations and quantum transport

    NASA Astrophysics Data System (ADS)

    Wurm, Jürgen; Richter, Klaus; Adagideli, Inanç

    2011-11-01

    We investigate the effect of different edge types on the statistical properties of both the energy spectrum of closed graphene billiards and the conductance of open graphene cavities in the semiclassical limit. To this end, we use the semiclassical Green's function for ballistic graphene flakes [see J. Wurm, K. Richter, and İ. Adagideli, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.075468 84, 075468 (2011)]. First, we study the spectral two-point correlation function or, more precisely, its Fourier transform the spectral form factor, starting from the graphene version of Gutzwiller's trace formula for the oscillating part of the density of states. We calculate the two leading-order contributions to the spectral form factor, paying particular attention to the influence of the edge characteristics of the system. Then, we consider transport properties of open graphene cavities. We derive generic analytical expressions for the classical conductance, the weak localization correction, the size of the universal conductance fluctuations, and the shot-noise power of a ballistic graphene cavity. Again, we focus on the effects of the edge structure. For both the conductance and the spectral form factor, we find that edge-induced pseudospin interference affects the results significantly. In particular, intervalley coupling mediated through scattering from armchair edges is the key mechanism that governs the coherent quantum interference effects in ballistic graphene cavities.

  3. Sparsity-regularized image reconstruction of decomposed K-edge data in spectral CT

    NASA Astrophysics Data System (ADS)

    Xu, Qiaofeng; Sawatzky, Alex; Anastasio, Mark A.; Schirra, Carsten O.

    2014-05-01

    The development of spectral computed tomography (CT) using binned photon-counting detectors has garnered great interest in recent years and has enabled selective imaging of K-edge materials. A practical challenge in CT image reconstruction of K-edge materials is the mitigation of image artifacts that arise from reduced-view and/or noisy decomposed sinogram data. In this note, we describe and investigate sparsity-regularized penalized weighted least squares-based image reconstruction algorithms for reconstructing K-edge images from few-view decomposed K-edge sinogram data. To exploit the inherent sparseness of typical K-edge images, we investigate use of a total variation (TV) penalty and a weighted sum of a TV penalty and an ℓ1-norm with a wavelet sparsifying transform. Computer-simulation and experimental phantom studies are conducted to quantitatively demonstrate the effectiveness of the proposed reconstruction algorithms.

  4. A GIHS-based spectral preservation fusion method for remote sensing images using edge restored spectral modulation

    NASA Astrophysics Data System (ADS)

    Zhou, Xiran; Liu, Jun; Liu, Shuguang; Cao, Lei; Zhou, Qiming; Huang, Huawen

    2014-02-01

    High spatial resolution and spectral fidelity are basic standards for evaluating an image fusion algorithm. Numerous fusion methods for remote sensing images have been developed. Some of these methods are based on the intensity-hue-saturation (IHS) transform and the generalized IHS (GIHS), which may cause serious spectral distortion. Spectral distortion in the GIHS is proven to result from changes in saturation during fusion. Therefore, reducing such changes can achieve high spectral fidelity. A GIHS-based spectral preservation fusion method that can theoretically reduce spectral distortion is proposed in this study. The proposed algorithm consists of two steps. The first step is spectral modulation (SM), which uses the Gaussian function to extract spatial details and conduct SM of multispectral (MS) images. This method yields a desirable visual effect without requiring histogram matching between the panchromatic image and the intensity of the MS image. The second step uses the Gaussian convolution function to restore lost edge details during SM. The proposed method is proven effective and shown to provide better results compared with other GIHS-based methods.

  5. Joint demosaicking and zooming using moderate spectral correlation and consistent edge map

    NASA Astrophysics Data System (ADS)

    Zhou, Dengwen; Dong, Weiming; Chen, Wengang

    2014-07-01

    The recently published joint demosaicking and zooming algorithms for single-sensor digital cameras all overfit the popular Kodak test images, which have been found to have higher spectral correlation than typical color images. Their performance perhaps significantly degrades on other datasets, such as the McMaster test images, which have weak spectral correlation. A new joint demosaicking and zooming algorithm is proposed for the Bayer color filter array (CFA) pattern, in which the edge direction information (edge map) extracted from the raw CFA data is consistently used in demosaicking and zooming. It also moderately utilizes the spectral correlation between color planes. The experimental results confirm that the proposed algorithm produces an excellent performance on both the Kodak and McMaster datasets in terms of both subjective and objective measures. Our algorithm also has high computational efficiency. It provides a better tradeoff among adaptability, performance, and computational cost compared to the existing algorithms.

  6. Dynamic representation of spectral edges in guinea pig primary auditory cortex

    PubMed Central

    Montejo, Noelia

    2015-01-01

    The central representation of a given acoustic motif is thought to be strongly context dependent, i.e., to rely on the spectrotemporal past and present of the acoustic mixture in which it is embedded. The present study investigated the cortical representation of spectral edges (i.e., where stimulus energy changes abruptly over frequency) and its dependence on stimulus duration and depth of the spectral contrast in guinea pig. We devised a stimulus ensemble composed of random tone pips with or without an attenuated frequency band (AFB) of variable depth. Additionally, the multitone ensemble with AFB was interleaved with periods of silence or with multitone ensembles without AFB. We have shown that the representation of the frequencies near but outside the AFB is greatly enhanced, whereas the representation of frequencies near and inside the AFB is strongly suppressed. These cortical changes depend on the depth of the AFB: although they are maximal for the largest depth of the AFB, they are also statistically significant for depths as small as 10 dB. Finally, the cortical changes are quick, occurring within a few seconds of stimulus ensemble presentation with AFB, and are very labile, disappearing within a few seconds after the presentation without AFB. Overall, this study demonstrates that the representation of spectral edges is dynamically enhanced in the auditory centers. These central changes may have important functional implications, particularly in noisy environments where they could contribute to preserving the central representation of spectral edges. PMID:25744885

  7. Identification and Spectral Classification of Red Dwarf Common Proper Motion Binary Stars Part 2

    NASA Astrophysics Data System (ADS)

    Chivers, James

    2014-10-01

    The position angle, separation, and spectral class of 1042 common proper motion red dwarf binary stars are reported based on data-mining the Sloan Digital Sky Survey Data Release 10. 727 of these are new discoveries.

  8. On the location of spectral edges in \\ {Z}-periodic media

    NASA Astrophysics Data System (ADS)

    Exner, Pavel; Kuchment, Peter; Winn, Brian

    2010-11-01

    Periodic second-order ordinary differential operators on \\ {R} are known to have the edges of their spectra to occur only at the spectra of periodic and anti-periodic boundary value problems. The multi-dimensional analog of this property is false, as was shown in a 2007 paper by some of the authors of this paper. However, one sometimes encounters the claims that in the case of a single periodicity (i.e., with respect to the lattice \\ {Z}), the 1D property still holds, and spectral edges occur at the periodic and anti-periodic spectra only. In this work, we show that even in the simplest case of quantum graphs this is not true. It is shown that this is true if the graph consists of a 1D chain of finite graphs connected by single edges, while if the connections are formed by at least two edges, the spectral edges can already occur away from the periodic and anti-periodic spectra. This paper is dedicated to the memory of P Duclos.

  9. K-edge ratio method for identification of multiple nanoparticulate contrast agents by spectral CT imaging

    PubMed Central

    Ghadiri, H; Ay, M R; Shiran, M B; Soltanian-Zadeh, H

    2013-01-01

    Objective: Recently introduced energy-sensitive X-ray CT makes it feasible to discriminate different nanoparticulate contrast materials. The purpose of this work is to present a K-edge ratio method for differentiating multiple simultaneous contrast agents using spectral CT. Methods: The ratio of two images relevant to energy bins straddling the K-edge of the materials is calculated using an analytic CT simulator. In the resulting parametric map, the selected contrast agent regions can be identified using a thresholding algorithm. The K-edge ratio algorithm is applied to spectral images of simulated phantoms to identify and differentiate up to four simultaneous and targeted CT contrast agents. Results: We show that different combinations of simultaneous CT contrast agents can be identified by the proposed K-edge ratio method when energy-sensitive CT is used. In the K-edge parametric maps, the pixel values for biological tissues and contrast agents reach a maximum of 0.95, whereas for the selected contrast agents, the pixel values are larger than 1.10. The number of contrast agents that can be discriminated is limited owing to photon starvation. For reliable material discrimination, minimum photon counts corresponding to 140 kVp, 100 mAs and 5-mm slice thickness must be used. Conclusion: The proposed K-edge ratio method is a straightforward and fast method for identification and discrimination of multiple simultaneous CT contrast agents. Advances in knowledge: A new spectral CT-based algorithm is proposed which provides a new concept of molecular CT imaging by non-iteratively identifying multiple contrast agents when they are simultaneously targeting different organs. PMID:23934964

  10. Active-Optical Sensors Using Red NDVI Compared to Red Edge NDVI for Prediction of Corn Grain Yield in North Dakota, U.S.A.

    PubMed Central

    Sharma, Lakesh K.; Bu, Honggang; Denton, Anne; Franzen, David W.

    2015-01-01

    Active-optical sensor readings from an N non-limiting area standard established within a farm field are used to predict yield in the standard. Lower yield predictions from sensor readings obtained from other parts of the field outside of the N non-limiting standard area indicate a need for supplemental N. Active-optical sensor algorithms for predicting corn (Zea mays, L.) yield to direct in-season nitrogen (N) fertilization in corn utilize red NDVI (normalized differential vegetative index). Use of red edge NDVI might improve corn yield prediction at later growth stages when corn leaves cover the inter-row space resulting in “saturation” of red NDVI readings. The purpose of this study was to determine whether the use of red edge NDVI in two active-optical sensors (GreenSeeker™ and Holland Scientific Crop Circle™) improved corn yield prediction. Nitrogen rate experiments were established at 15 sites in North Dakota (ND). Sensor readings were conducted at V6 and V12 corn. Red NDVI and red edge NDVI were similar in the relationship of readings with yield at V6. At V12, the red edge NDVI was superior to the red NDVI in most comparisons, indicating that it would be most useful in developing late-season N application algorithms. PMID:26540057

  11. Active-Optical Sensors Using Red NDVI Compared to Red Edge NDVI for Prediction of Corn Grain Yield in North Dakota, U.S.A.

    PubMed

    Sharma, Lakesh K; Bu, Honggang; Denton, Anne; Franzen, David W

    2015-01-01

    Active-optical sensor readings from an N non-limiting area standard established within a farm field are used to predict yield in the standard. Lower yield predictions from sensor readings obtained from other parts of the field outside of the N non-limiting standard area indicate a need for supplemental N. Active-optical sensor algorithms for predicting corn (Zea mays, L.) yield to direct in-season nitrogen (N) fertilization in corn utilize red NDVI (normalized differential vegetative index). Use of red edge NDVI might improve corn yield prediction at later growth stages when corn leaves cover the inter-row space resulting in "saturation" of red NDVI readings. The purpose of this study was to determine whether the use of red edge NDVI in two active-optical sensors (GreenSeeker™ and Holland Scientific Crop Circle™) improved corn yield prediction. Nitrogen rate experiments were established at 15 sites in North Dakota (ND). Sensor readings were conducted at V6 and V12 corn. Red NDVI and red edge NDVI were similar in the relationship of readings with yield at V6. At V12, the red edge NDVI was superior to the red NDVI in most comparisons, indicating that it would be most useful in developing late-season N application algorithms. PMID:26540057

  12. Spectral cola or how to turn green laser light red

    NASA Astrophysics Data System (ADS)

    Forró, Csaba; Mettan, Xavier; Humair, Thibaud

    2014-11-01

    A green laser pointer shone through a glass of cola will appear red when looking from above the glass. Lowering the laser so that it is deeper in the cola, the colour will vary from orange to deep red. Fluorescence and absorption spectra were recorded consistent with the reddening of the laser. The depth dependence of the colour of the immersed laser is attributed to a more significant absorption of the short wavelengths by the cola, making the laser look redder as it is lowered deeper into the cola. To confirm this hypothesis, we simulated the fluorescence spectrum we would get at various depths by applying the Lambert law on our measured fluorescence spectrum. These spectra were then converted into red, green and blue (RGB) values. These values were compared to those measured on images of the immersed laser beam at corresponding depths.

  13. Red and near-infrared spectral reflectance of snow

    NASA Technical Reports Server (NTRS)

    Obrien, H. W.; Munis, R. H.

    1975-01-01

    The spectral reflectance of snow in the range of 0.60 to 2.50 microns wavelengths was studied in a cold laboratory using natural snow and simulated preparations of snow. A white barium sulfate powder was used as the standard for comparison. The high reflectance (usually nearly 100%) of fresh natural snow in visible wavelengths declines rapidly at wavelengths longer than the visible, as the spectral absorption coefficients of ice increase. Aging snow becomes only somewhat less reflective than fresh snow in the visible region and usually retains a reflectance greater than 80%. In the near infrared, aging snow tends to become considerably less reflective than fresh snow.

  14. Determination of optimal wavelet denoising parameters for red edge feature extraction from hyperspectral data

    NASA Astrophysics Data System (ADS)

    Shafri, Helmi Z. M.; Yusof, Mohd R. M.

    2009-05-01

    A study of wavelet denoising on hyperspectral reflectance data, specifically the red edge position (REP) and its first derivative is presented in this paper. A synthetic data set was created using a sigmoid to simulate the red edge feature for this study. The sigmoid is injected with Gaussian white noise to simulate noisy reflectance data from handheld spectroradiometers. The use of synthetic data enables better quantification and statistical study of the effects of wavelet denoising on the features of hyperspectral data, specifically the REP. The simulation study will help to identify the most suitable wavelet parameters for denoising and represents the applicability of the wavelet-based denoising procedure in hyperspectral sensing for vegetation. The suitability of the thresholding rules and mother wavelets used in wavelet denoising is evaluated by comparing the denoised sigmoid function with the clean sigmoid, in terms of the shift in the inflection point meant to represent the REP, and also the overall change in the denoised signal compared with the clean one. The VisuShrink soft threshold was used with rescaling based on the noise estimate, in conjunction with wavelets of the Daubechies, Symlet and Coiflet families. It was found that for the VisuShrink threshold with single level noise estimate rescaling, the Daubechies 9 and Symlet 8 wavelets produced the least distortion in the location of sigmoid inflection point and the overall curve. The selected mother wavelets were used to denoise oil palm reflectance data to enable determination of the red edge position by locating the peak of the first derivative.

  15. A novel edge-preserving nonnegative matrix factorization method for spectral unmixing

    NASA Astrophysics Data System (ADS)

    Bao, Wenxing; Ma, Ruishi

    2015-12-01

    Spectral unmixing technique is one of the key techniques to identify and classify the material in the hyperspectral image processing. A novel robust spectral unmixing method based on nonnegative matrix factorization(NMF) is presented in this paper. This paper used an edge-preserving function as hypersurface cost function to minimize the nonnegative matrix factorization. To minimize the hypersurface cost function, we constructed the updating functions for signature matrix of end-members and abundance fraction respectively. The two functions are updated alternatively. For evaluation purpose, synthetic data and real data have been used in this paper. Synthetic data is used based on end-members from USGS digital spectral library. AVIRIS Cuprite dataset have been used as real data. The spectral angle distance (SAD) and abundance angle distance(AAD) have been used in this research for assessment the performance of proposed method. The experimental results show that this method can obtain more ideal results and good accuracy for spectral unmixing than present methods.

  16. Seeing red in cyclic stratigraphy: Spectral noise estimation for astrochronology

    NASA Astrophysics Data System (ADS)

    Meyers, Stephen R.

    2012-09-01

    Fundamental to the development of astronomical time scales is the recognition of oscillatory variability within stratigraphic data and its evaluation relative to a null "noise" hypothesis. In this study, Monte Carlo simulations are used to investigate the suitability of two commonly used noise hypotheses (the "conventional" and "robust" AR1 approaches), and the results highlight important limitations in both for cyclostratigraphic application. Perhaps most problematic, the robust AR1 method can result in inflated confidence level estimates and excessive clumping of false positives within the low frequency portion of the spectrum, especially when the underlying noise process has a high lag-1 autocorrelation. Given typical cyclostratigraphic records, this technique will often impose "significant" eccentricity band variability, even in the case of pure AR1 noise. An alternative spectral noise estimation method is proposed to overcome these problems, which simultaneously allows for departures from the AR1 assumption, and obtains high statistical power—that is, the ability to accurately identify astronomical signals when they are present in the data. We apply the method to un-tunedδ18O data from Miocene sediments of the Ceara Rise, indicating statistically significant spectral power at frequencies that are consistent with the published orbital interpretation of Weedon et al. (1997). Furthermore, evaluation of the frequency arrangement of the significant spatial bedding periods, using the average spectral misfit method for astrochronologic testing, reveals that the null hypothesis of no orbital influence can be rejected with a high degree of confidence (the 99.8% confidence level).

  17. High-Resolution Spectral Analysis of KI Lines in Unusually Red & Blue L Dwarfs

    NASA Astrophysics Data System (ADS)

    Khalida Alam, Munazza; Camnasio, Sara; Rice, Emily L.; Cruz, Kelle L.; Faherty, Jacqueline K.; Mace, Gregory N.; Martin, Emily; Logsdon, Sarah E.; McLean, Ian S.; Brown Dwarfs in New York City (Bdnyc)

    2015-01-01

    L dwarfs have a range of near-infrared colors at a given optically-defined spectral subtype. L dwarfs of the same spectral subtype are thought to have similar surface temperatures, and the presence of extreme near-IR colors in some L dwarfs suggests that parameters other than temperature influence their spectra. For some of these objects, diagnostic spectral features indicate the cause of extreme near-IR color. Blue L dwarfs that have low metallicity spectral features, called subdwarfs, are known to have old ages. Red L dwarfs that have low surface gravity spectral features are known to be young. The spectra of some blue and red L dwarfs do not show evidence for low metallicity or low gravity. This project investigates the cause of extreme color in these photometric outliers by comparing spectral line measurements for a sample of red, blue, and standard L dwarfs to elucidate their underlying atmospheric and physical properties. We use KI lines to make these comparisons because they are pressure-broadened and therefore sensitive to temperature, gravity, and metallicity. We use high-resolution NIRSPEC J band spectra to measure equivalent widths, line depths, and full width at half maximum (FWHM) of KI lines at 1.1773 um, 1.1776 um, 1.2436 um, and 1.2525 um. Consistent with trends in the literature, our preliminary results suggest that unusually blue L dwarfs are field age or older.

  18. Hybrid integrated photodetector with flat-top steep-edge spectral response.

    PubMed

    Fan, Xinye; Huang, Yongqing; Ren, Xiaomin; Duan, Xiaofeng; Hu, Fuquan; Wang, Qi; Cai, Shiwei; Zhang, Xia

    2012-08-20

    Hybrid integrated photodetectors with flat-top steep-edge spectral responses that consist of an Si-based multicavity Fabry-Perot (F-P) filter and an InP-based p-i-n absorption structure (with a 0.2 μm In(0.53)Ga(0.47)As absorption layer), have been designed and fabricated. The performance of the hybrid integrated photodetectors is theoretically investigated by including key factors such as the thickness of each cavity, the pairs of each reflecting mirror, and the thickness of the benzocyclobutene bonding layer. The device is fabricated by bonding an Si-based multicavity F-P filter with an InP-based p-i-n absorption structure. A hybrid integrated photodetector with a peak quantum efficiency of 55% around 1549.2 nm, the -0.5 dB band of 0.43 nm, the 25 dB band of 1.06 nm, and 3 dB bandwidth more than 16 GHz, is simultaneously obtained. Based on multicavity F-P structure, this device has good flat-top steep-edge spectral response. PMID:22907001

  19. Living on the edge: Space use of Eurasian red squirrels in marginal high-elevation habitat

    NASA Astrophysics Data System (ADS)

    Romeo, Claudia; Wauters, Lucas A.; Preatoni, Damiano; Tosi, Guido; Martinoli, Adriano

    2010-11-01

    In marginal habitats located at the edge of a species' range, environmental conditions are frequently extreme and individuals may be subject to different selective pressures compared to central populations. These so-called edge or marginal populations tend to have lower densities and reproductive rates than populations located in more suitable habitats, but little is known about local adaptations in spacing behavior. We studied space use and social organization in a population of Eurasian red squirrels ( Sciurus vulgaris) in a high-elevation marginal habitat of dwarf mountain pine ( Pinus mugo) and compared it with spacing patterns in high-quality Scots pine ( Pinus sylvestris) forest at lower-elevation. Home ranges and core areas were larger in the marginal habitat. In both habitats, males used larger home ranges than females, but sex differences in core area size were significant only in the edge population. Patterns of core area overlap were similar in both habitats with intra-sexual territoriality among adult females and higher degrees of inter-sexual overlap, typical for the species throughout its range. However, low densities in the edge population resulted in higher female by males overlap in spring-summer, suggesting males increased home ranges and core areas during mating season to augment access to estrus females. Thus, in the marginal habitat, with low food abundance and low population densities, linked with extreme winter conditions, squirrels, especially males, used large home ranges. Finally, squirrels responded more strongly to variation in food availability (inverse relation between home range size and seed abundance), and even to fluctuations in density (inverse relation between core area size and density of animals of the same sex), in the marginal than in the high-quality habitat, suggesting high behavioral plasticity to respond to the ecological constraints in marginal habitats.

  20. Spectrally narrowed leaky waveguide edge emission and transient electrluminescent dynamics of OLEDs

    SciTech Connect

    Zhengqing, Gan

    2010-01-01

    In summary, there are two major research works presented in this dissertation. The first research project (Chapter 4) is spectrally narrowed edge emission from Organic Light Emitting Diodes. The second project (Chapter 5) is about transient electroluminescent dynamics in OLEDs. Chapter 1 is a general introduction of OLEDs. Chapter 2 is a general introduction of organic semiconductor lasers. Chapter 3 is a description of the thermal evaporation method for OLED fabrication. The detail of the first project was presented in Chapter 4. Extremely narrowed spectrum was observed from the edge of OLED devices. A threshold thickness exists, above which the spectrum is narrow, and below which the spectrum is broad. The FWHM of spectrum depends on the material of the organic thin films, the thickness of the organic layers, and length of the OLED device. A superlinear relationship between the output intensity of the edge emission and the length of the device was observed, which is probably due to the misalignment of the device edge and the optical fiber detector. The original motivation of this research is for organic semiconductor laser that hasn't been realized due to the extremely high photon absorption in OLED devices. Although we didn't succeed in fabricating an electrically pumped organic laser diode, we made a comprehensive research in edge emission of OLEDs which provides valuable results in understanding light distribution and propagation in OLED devices. Chapter 5 focuses on the second project. A strong spike was observed at the falling edge of a pulse, and a long tail followed. The spike was due to the recombination of correlated charge pair (CCP) created by trapped carriers in guest molecules of the recombination zone. When the bias was turned off, along with the decreasing of electric field in the device, the electric field induced quenching decreases and the recombination rate of the CCP increases which result in the spike. This research project provides a

  1. Correlation analysis of simulated MODIS vegetation indices and the red edge and rice agricultural parameter

    NASA Astrophysics Data System (ADS)

    Cheng, Qian; Wu, Xiuju

    2007-10-01

    In this study, Hyperspectral data of two variety of rice (common rice and hybrid rice) in whole growing stage during 2002 and 2003 was measured using the ASD FieldSpec UV/VNIR Spectroradiometer with resolution of 3 nm, and the LAI and leaf chlorophyll content of rice agricultural parameter were obtained. Analyses of the correlation between rice agricultural parameter, and hyperspectal data, normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and the red-edge position (REP) were studied. Results showed that a strong non-linear correlation was found between the rice LAI of two varieties and REP. The REP, EVI and NDVI were well related with LAI for the common rice, but the REP and EVI were more sensitive than the NDVI to rice LAI for the hybrid rice because of different body for two variety rice.

  2. Experimental spectral measurements of heavy K-edge filtered beams for x-ray computed mammotomography

    PubMed Central

    Crotty, D J; McKinley, R L; Tornai, M P

    2012-01-01

    A dual modality computed mammotomography (CmT) and single photon emission computed tomography (SPECT) system for dedicated 3D breast imaging is in development. Using heavy K-edge filtration, the CmT component narrows the energy spectrum of the cone-shaped x-ray beam incident on the patient’s pendant, uncompressed breast. This quasi-monochromatic beam is expected to improve discrimination of tissue with similar attenuation coefficients while restraining absorbed dose to below that of dual view mammography. Previous simulation studies showed the optimal energy that maximizes dose efficiency for a 50/50% adipose/glandular breast is between 30 and 40 keV. This study experimentally validates these results using pre-breast and post-breast spectral measurements made under tungsten tube voltages between 40 and 100 kVp using filter materials with K-edge values ranging from 15 to 70 keV. Different filter material thicknesses are used, approximately equivalent to the 200th and 500th attenuating value layer (VL) thickness. Cerium (K = 40.4 keV) filtered post-breast spectra for 8–18 cm breasts are measured for a range of breast compositions. Figures of merit include mean beam energy, spectral full-width at tenth-maximum, beam hardening and dose for the range of breast sizes. Measurements corroborate simulation results, indicating that for a given dose, a 200th VL of cerium filtration may have optimal performance in the dedicated mammotomography paradigm. PMID:17228108

  3. Photon counting spectral CT: improved material decomposition with K-edge-filtered x-rays

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2012-03-01

    Photon counting spectral computed tomography (PCSCT) provides material selective CT imaging at a single CT scan and fixed tube voltage. The PCSCT data are acquired in several energy ranges (bins) arranged over the x-ray spectrum. The quasi-monoenergetic CT images are acquired in these energy bins and are used for material decomposition. The PCSCT exhibits inherent limitations when material decomposition is performed using energy bins. For effective material decomposition, the energy bins used for material decomposition should be sufficiently narrow and well separated. However, when narrow bins are used, a large fraction of the detected x-ray counts is lost and statistical noise is increased. Alternatively, the x-ray spectrum can be split into a few larger bins with no gap in between and all detected x-ray photons can be used for material decomposition. However, in this case the energy bins are too wide and not well separated, which results in suboptimal material decomposition. The above contradictory requirements can be resolved if the x-ray photons are physically removed from the regions of the energy spectrum between the energy bins. Such a selective removal can be performed using filtration of the x-ray beam by high-Z filter materials with appropriate positions of K-edge energies. The K-edge filtration of x-rays can, therefore, provide necessary gaps between the energy bins with no dose penalty to the patient. In the current work, we proposed using selective K-edge filtration of x-rays in PCSCT and performed the first experimental investigation of this approach. The PCSCT system included a cadmium zinc telluride semiconductor detector with 2 × 256 pixels and 1 × 1 mm2 pixel size, and five energy bins. The CT phantom had 14 cm diameter and included contrast elements of iodine, gold and calcifications with clinically relevant concentrations. The tube voltages of 60, 90 and 120 kVp were used. K-edge filters based on Ba (Ek = 37.44 keV) were used for a 60 kVp tube

  4. Spectral Characterization of Suspected Acid Deposition Damage in Red Spruce (picea Rubens) Stands from Vermont

    NASA Technical Reports Server (NTRS)

    Vogelmann, J. E.; Rock, B. N.

    1985-01-01

    In an attempt to demonstrate the utility of remote sensing systems to monitor sites of suspected acid rain deposition damage, intensive field activities, coupled with aircraft overflights, were centered on red spruce stands in Vermont during August and September of 1984. Remote sensing data were acquired using the Airborne Imaging Spectrometer, Thematic Mapper Simulator, Barnes Model 12 to 1000 Modular Multiband Radiometer and Spectron Engineering Spectrometer (the former two flown on the NASA C-130; the latter two on A Bell UH-1B Iroquois Helicopter). Field spectral data were acquired during the week of the August overflights using a high spectral resolution spectrometer and two broad-band radiometers. Preliminary analyses of these data indicate a number of spectral differences in vegetation between high and low damage sites. Some of these differences are subtle, and are observable only with high spectral resolution sensors; others are less subtle and are observable using broad-band sensors.

  5. High Broadband Spectral Resolving Transition-Edge Sensors for High Count-Rate Astrophysical Applications

    NASA Technical Reports Server (NTRS)

    Smith, Stephen

    2011-01-01

    We are developing arrays of transition-edge sensor (TES) X-ray detectors optimized for high count-rate solar astronomy applications where characterizing the high velocity motions of X-ray jets in solar flares is of particular interest. These devices are fabricated on thick Si substrates and consist of 35x35micron^2 TESs with 4.5micron thick, 60micron pitch, electroplated absorbers. We have tested devices fabricated with different geometric stem contact areas with the TES and surrounding substrate area, which allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between the stem contact area and a non-Gaussian broadening in the spectral line shape consistent with athermal phonon loss. When the contact area is minimized we have obtained remarkable board-band spectral resolving capabilities of 1.3 plus or minus 0.leV at an energy of 1.5 keV, 1.6 plus or minus 0.1 eV at 5.9 keV and 2.0 plus or minus 0.1 eV at 8 keV. This, coupled with a capability of accommodating 100's of counts per second per pixel makes these devices an exciting prospect of future x-ray astronomy applications.

  6. Small Pitch Transition-Edge Sensors with Broadband High Spectral Resolution for Solar Physics

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Adams, J. S.; Eckart, M. E.; Smith, Adams; Bailey, C. N.; Bandler, S. R.; Chevenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.

    2012-01-01

    We are developing small pitch transition-edge sensor (TES) X-ray detectors optimized for solar astronomy. These devices are fabricated on thick Si substrates with embedded Cu heat-sink layer. We use 35 x 35 square micrometers Mo/Au TESs with 4.5 micrometer thick Au absorbers. We have tested devices with different geometric absorber stem contact areas with the TES and surrounding substrate area. This allows us to investigate the loss of athermal phonons to the substrate. Results show a correlation between thc stem contact area and a broadening in the spectral line shape indicative of athermal phonon loss. When the contact area is minimized we have obtained exceptional broadband spectral resolution of 1.28 plus or minus 0.03 eV at an energy of 1.5 keV, 1.58 plus or minus 0.07 eV at 5.9 keV and 1.96 plus or minus 0.08 eV at 8 keV. The linearity in the measured gain scale is understood in the context of the longitudinal proximity effect from the electrical bias leads resulting in transition characteristics that are strongly dependent upon TES size.

  7. Field and airborne spectral characterization of suspected damage in red spruce (picea rubens) from Vermont

    NASA Technical Reports Server (NTRS)

    Rock, B. N.; Vogelmann, J. E.; Williams, D. L.

    1985-01-01

    The utilization of remote sensing to monitor forest damage due to acid deposition is investigated. Spectral and water measurements and aircraft radiance data of red spruce and balsam fir, collected in Camels Hump Mountain and Ripton, Vermont between August 13-20, 1984, are analyzed to evaluate the damage levels of the trees. Variations in reflectance features and canopy moisture content are studied. It is observed that damage correlates with elevation (greater damage at higher elevations); xylem water column tension is greater at higher damage sites; and a 'blue shift' is indicated in the spectral data at high damage sites.

  8. Spectral fluorescent properties of tissues in vivo with excitation in the red wavelength range

    NASA Astrophysics Data System (ADS)

    Stratonnikov, Alexander A.; Loschenov, Victor B.; Klimov, D. V.; Edinac, N. E.; Wolnukhin, V. A.; Strashkevich, I. A.

    1997-12-01

    The spectral fluorescence analysis is a promising method for differential tissue diagnostic. Usually the UV and visible light is used for fluorescence excitation with emission registration in the visible wavelength range. The light penetration length in this wavelength range is very small allowing one to analyze only the surface region of the tissue. Here we present the tissue fluorescent spectra in vivo excited in the red wavelength region. As excitation light source we used compact He-Ne laser (632.8 nm) and observed the fluorescence in 650 - 800 nm spectral range. The various tissues including normal skin, psoriasis, tumors, necrosis as well as photosensitized tissues have been measured.

  9. [Comparison of red edge parameters of winter wheat canopy under late frost stress].

    PubMed

    Wu, Yong-feng; Hu, Xin; Lü, Guo-hua; Ren, De-chao; Jiang, Wei-guo; Song, Ji-qing

    2014-08-01

    In the present study, late frost experiments were implemented under a range of subfreezing temperatures (-1 - -9 degrees C) by using a field movable climate chamber (FMCC) and a cold climate chamber, respectively. Based on the spectra of winter wheat canopy measured at noon on the first day after the frost experiments, red edge parameters REP, Dr, SDr, Dr(min), Dr/Dr(min) and Dr/SDr were extracted using maximum first derivative spectrum method (FD), linear four-point interpolation method (FPI), polynomial fitting method (POLY), inverted Gaussian fitting method (IG) and linear extrapolation technique (LE), respectively. The capacity of the red edge parameters to detect late frost stress was explicated from the aspects of the early, sensitivity and stability through correlation analysis, linear regression modeling and fluctuation analysis. The result indicates that except for REP calculated from FPI and IG method in Experiment 1, REP from the other methods was correlated with frost temperatures (P < 0.05). Thereinto, significant levels (P) of POLY and LE methods all reached 0.01. Except for POLY method in Experiment 2, Dr/SDr from the other methods were all significantly correlated with frost temperatures (P < 0.01). REP showed a trend to shift to short-wave band with decreasing temperatures. The lower the temperature, the more obvious the trend is. Of all the REP, REP calculated by LE method had the highest correlation with frost temperatures which indicated that LE method is the best for REP extraction. In Experiment 1 and 2, only Dr(min) and Dr/Dr(min), calculated by FD method simultaneously achieved the requirements for the early (their correlations with frost temperatures showed a significant level P < 0.01), sensitivity (abso- lute value of the slope of fluctuation coefficient is greater than 2.0) and stability (their correlations with frost temperatures al- ways keep a consistent direction). Dr/SDr calculated from FD and IG methods always had a low sensitivity

  10. [Comparison of red edge parameters of winter wheat canopy under late frost stress].

    PubMed

    Wu, Yong-feng; Hu, Xin; Lü, Guo-hua; Ren, De-chao; Jiang, Wei-guo; Song, Ji-qing

    2014-08-01

    In the present study, late frost experiments were implemented under a range of subfreezing temperatures (-1 - -9 degrees C) by using a field movable climate chamber (FMCC) and a cold climate chamber, respectively. Based on the spectra of winter wheat canopy measured at noon on the first day after the frost experiments, red edge parameters REP, Dr, SDr, Dr(min), Dr/Dr(min) and Dr/SDr were extracted using maximum first derivative spectrum method (FD), linear four-point interpolation method (FPI), polynomial fitting method (POLY), inverted Gaussian fitting method (IG) and linear extrapolation technique (LE), respectively. The capacity of the red edge parameters to detect late frost stress was explicated from the aspects of the early, sensitivity and stability through correlation analysis, linear regression modeling and fluctuation analysis. The result indicates that except for REP calculated from FPI and IG method in Experiment 1, REP from the other methods was correlated with frost temperatures (P < 0.05). Thereinto, significant levels (P) of POLY and LE methods all reached 0.01. Except for POLY method in Experiment 2, Dr/SDr from the other methods were all significantly correlated with frost temperatures (P < 0.01). REP showed a trend to shift to short-wave band with decreasing temperatures. The lower the temperature, the more obvious the trend is. Of all the REP, REP calculated by LE method had the highest correlation with frost temperatures which indicated that LE method is the best for REP extraction. In Experiment 1 and 2, only Dr(min) and Dr/Dr(min), calculated by FD method simultaneously achieved the requirements for the early (their correlations with frost temperatures showed a significant level P < 0.01), sensitivity (abso- lute value of the slope of fluctuation coefficient is greater than 2.0) and stability (their correlations with frost temperatures al- ways keep a consistent direction). Dr/SDr calculated from FD and IG methods always had a low sensitivity

  11. Quantitative Spectral Morphology Analysis of Unusually Red and Blue L Dwarfs

    NASA Astrophysics Data System (ADS)

    Camnasio, Sara; Khalida Alam, Munazza; Rice, Emily L.; Cruz, Kelle L.; Faherty, Jacqueline K.; Mace, Gregory N.; Martin, Emily; Logsdon, Sarah E.; McLean, Ian S.; Brown Dwarfs in New York City (BDNYC)

    2016-01-01

    In an effort to constrain the properties of photometric color outliers, we present a quantitative spectral morphology analysis of medium-resolution NIRSPEC (R~2,000), SpeX cross-dispersed (R~2,000), Palomar TripleSpec (R~2600), and Magellan FIRE (R~6000) J-band spectra for a sample of unusually red and blue L dwarfs. Some red L dwarfs are low surface gravity, young objects whose spectra present weak Na I doublets and FeH absorption bands, but strong VO features (Cruz et al. 2009). Some blue L dwarfs are subdwarfs with low metallicity spectral features such as greater H2 absorption, stronger metal hydride bands, and enhanced TiO absorption (Burgasser et al 2008c). We fit 3rd order polynomials to the pseudo-continuum in order to provide a quantitative comparison of spectral morphology with other peculiar L dwarfs, field standards, young L dwarfs, and L subdwarf. The results indicated that the coefficients of the fit correlate with spectral type, but are independent of color. This newly found trend provides a parameter which can be utilized as an additional tool in characterizing quantifiable differences in the spectra of brown dwarfs. Furthermore, this method can be applied in studying the atmospheric properties of exoplanets, given their similarities with brown dwarfs in mass and photospheric properties.

  12. Red-edge vegetation indices for detecting and assessing disturbances in Norway spruce dominated mountain forests

    NASA Astrophysics Data System (ADS)

    Adamczyk, Joanna; Osberger, Antonia

    2015-05-01

    Here we propose an approach to enhance the detection and assessment of forest disturbances in mountain areas based on red-edge reflectance. The research addresses the need for improved monitoring of areas included in the European Natura 2000 network. Thirty-eight vegetation indices (VI) are assessed for sensitivity to topographic variations. A separability analysis is performed for the resulting set of ten VI whereby two VI (PSSRc2, SR 800/550) are found most suitable for threshold-based OBIA classification. With a correlation analysis (SRCC) between VI and the training samples we identify Datt4 as suitable to represent the magnitude of forest disturbance. The provided information layers illustrate two combined phenomena that were derived by (1) an OBIA delineation and (2) continuous representation of the magnitude of forest disturbance. The satisfactory accuracy assessment results confirm that the approach is useful for operational tasks in the long-term monitoring of Norway spruce dominated forests in mountainous areas, with regard to forest disturbance.

  13. SPECTRAL TYPES OF RED SUPERGIANTS IN NGC 6822 AND THE WOLF-LUNDMARK-MELOTTE GALAXY

    SciTech Connect

    Levesque, Emily M.; Massey, Philip

    2012-07-15

    We present moderate-resolution spectroscopic observations of red supergiants (RSGs) in the low-metallicity Local Group galaxies NGC 6822 (Z = 0.4 Z{sub Sun} ) and Wolf-Lundmark-Melotte (WLM; Z = 0.1 Z{sub Sun} ). By combining these observations with reduction techniques for multislit data reduction and flux calibration, we are able to analyze spectroscopic data of 16 RSGs in NGC 6822 and spectrophotometric data of 11 RSGs in WLM. Using these observations, we determine spectral types for these massive stars, comparing them to Milky Way and Magellanic Cloud RSGs and thus extending observational evidence of the abundance-dependent shift of RSG spectral types to lower metallicities. In addition, we have uncovered two RSGs with unusually late spectral types (J000158.14-152332.2 in WLM, with a spectral type of M3 I, and J194453.46-144552.6 in NGC 6822, with a spectral type of M4.5 I) and a third RSG (J194449.96-144333.5 in NGC 6822) whose spectral type has varied from an M2.5 in 1997 to a K5 in 2008. All three of these stars could potentially be members of a recently discovered class of extreme RSG variables.

  14. Spectrally resolved fluorescence lifetime imaging of Nile red for measurements of intracellular polarity

    NASA Astrophysics Data System (ADS)

    Levitt, James A.; Chung, Pei-Hua; Suhling, Klaus

    2015-09-01

    Spectrally resolved confocal microscopy and fluorescence lifetime imaging have been used to measure the polarity of lipid-rich regions in living HeLa cells stained with Nile red. The emission peak from the solvatochromic dye in lipid droplets is at a shorter wavelength than other, more polar, stained internal membranes, and this is indicative of a low polarity environment. We estimate that the dielectric constant, ɛ, is around 5 in lipid droplets and 25<ɛ<40 in other lipid-rich regions. Our spectrally resolved fluorescence lifetime imaging microscopy (FLIM) data show that intracellular Nile red exhibits complex, multiexponential fluorescence decays due to emission from a short lifetime locally excited state and a longer lifetime intramolecular charge transfer state. We measure an increase in the average fluorescence lifetime of the dye with increasing emission wavelength, as shown using phasor plots of the FLIM data. We also show using these phasor plots that the shortest lifetime decay components arise from lipid droplets. Thus, fluorescence lifetime is a viable contrast parameter for distinguishing lipid droplets from other stained lipid-rich regions. Finally, we discuss the FLIM of Nile red as a method for simultaneously mapping both polarity and relative viscosity based on fluorescence lifetime measurements.

  15. Molar absorptivity (ε) and spectral characteristics of cyanidin-based anthocyanins from red cabbage.

    PubMed

    Ahmadiani, Neda; Robbins, Rebecca J; Collins, Thomas M; Giusti, M Monica

    2016-04-15

    Red cabbage extract contains mono and di-acylated cyanidin (Cy) anthocyanins and is often used as food colorants. Our objectives were to determine the molar absorptivity (ε) of different red cabbage Cy-derivatives and to evaluate their spectral behaviors in acidified methanol (MeOH) and buffers pH 1-9. Major red cabbage anthocyanins were isolated using a semi-preparatory HPLC, dried and weighed. Pigments were dissolved in MeOH and diluted with either MeOH (0.1% HCl) or buffers to obtain final concentrations between 5×10(-5) and 1×10(-3) mol/L. Spectra were recorded and ε calculated using Lambert-Beer's law. The ε in acidified MeOH and buffer pH 1 ranged between ~16,000-30,000 and ~13,000-26,000 L/mol cm, respectively. Most pigments showed higher ε in pH 8 than pH 2, and lowest ε between pH 4 and 6. There were bathochromic shifts (81-105 nm) from pH 1 to 8 and hypsochromic shifts from pH 8 to 9 (2-19 nm). Anthocyanins molecular structures and the media were important variables which greatly influenced their ε and spectral behaviors. PMID:26617032

  16. Cochlodinium polykrikoides red tide detection in the South Sea of Korea using spectral classification of MODIS data

    NASA Astrophysics Data System (ADS)

    Son, Young Baek; Ishizaka, Joji; Jeong, Jong-Chul; Kim, Hyun-Choel; Lee, Taehee

    2011-12-01

    To distinguish true red tide water (particularly Cochlodinium polykrikoides blooms) from non-red tide water (false satellite high chlorophyll water) in the South Sea of Korea, we developed a systematic classification method using spectral information from MODIS level products and applied it to five different harmful algal bloom events. Red tide and nonred tide waters were classified based on four different criteria. The first step revealed that the radiance peaks of potential red tide water occurred at 555 and 678 nm. The second step separated optically different waters that were influenced by relatively low and high contributions of colored dissolved organic matter (CDOM) (including detritus) to chlorophyll. The third and fourth steps discriminated red tide water from non-red tide water based on the blue-to-green ratio in areas with lower and higher contributions of CDOM to chlorophyll, respectively. After applying the red tide classification (using the four criteria), the spectral response of the red tide water, which is influenced by pigment concentration, showed different slopes for the blue and green bands (lower slope at blue bands and higher slope at green bands). The opposite result was found for non-red tide water, due to decreasing phytoplankton absorption and increasing detritus/CDOM absorption at blue bands. The results were well matched with the discoloration of water (blue to dark red/brown) and delineated the areal coverage of C. polykrikoides blooms, revealing the nature of spatial and temporal variations in red tides. This simple spectral classification method led to increase user accuracy for C. polykrikoides and non-red tide blooms (>46% and >97%) and provided a more reliable and robust identification of red tides over a wide range of oceanic environments than was possible using chlorophyll a concentration, chlorophyll anomaly, fluorescence analysis, or proposed red tide detection algorithms.

  17. Land cover classification in Ukrainian Carpathians using the MERIS Terrestrial Chlorophyl Index and red edge position from ENVISAT MERIS data

    NASA Astrophysics Data System (ADS)

    Lyalko, V. I.; Shportyuk, Z. M.; Sakhatskyi, O. L.; Sybirtseva, O. M.

    We present some results of a preliminary study of the possibility to use MERIS data for land cover classification in the Ukrainian Carpathians. The ENVISAT MERIS data (16 April 2004) with a rough space resolution of 1200m are used to calculate the red edge indices: the Red Edge Position (REP), MERIS Terrestrial Chlorophyll Index (MTCI) and NDVI. The classification using REP and MTCI images gives better results than with reflectance by the method of minimum distance to means (MMDM). The calculation results showed that the MERIS image with a rough space resolution provided moderate classification results: only coniferous forests and snow are well classified. MTCI is sensitive to a broad range of the chlorophyll contents and much less sensitive to topographical effect in mountain region. The investigation results show a good correlation between REP and MTCI and a high potential for monitoring for the ecosystems in mountain regions using a combination of both indices.

  18. Dipolar relaxation within the protein matrix of the green fluorescent protein: a red edge excitation shift study.

    PubMed

    Haldar, Sourav; Chattopadhyay, Amitabha

    2007-12-27

    The fluorophore in green fluorescent protein (GFP) is localized in a highly constrained environment, protected from the bulk solvent by the barrel-shaped protein matrix. We have used the wavelength-selective fluorescence approach (red edge excitation shift, REES) to monitor solvent (environment) dynamics around the fluorophore in enhanced green fluorescent protein (EGFP) under various conditions. Our results show that EGFP displays REES in buffer and glycerol, i.e., the fluorescence emission maxima exhibit a progressive shift toward the red edge, as the excitation wavelength is shifted toward the red edge of the absorption spectrum. Interestingly, EGFP displays REES when incorporated in reverse micelles of sodium bis(2-ethylhexyl)sulfosuccinate (AOT), independent of the hydration state. We interpret the observed REES to the constrained environment experienced by the EGFP fluorophore in the rigid protein matrix, rather than to the dynamics of the bulk solvent. These results are supported by the temperature dependence of REES and characteristic wavelength-dependent changes in fluorescence anisotropy. PMID:18052368

  19. Modelling the spectral energy distribution of the red giant in RS Ophiuchi: evidence for irradiation

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.; Kaminsky, B.; Rushton, M. T.; Evans, A.; Woodward, C. E.; Helton, L. A.; O'Brien, T. J.; Jones, D.; Elkin, V.

    2016-02-01

    We present an analysis of optical and infrared spectra of the recurrent nova RS Oph obtained during between 2006 and 2009. The best fit to the optical spectrum for 2006 September 28 gives Teff = 3900 K for log g = 2.0, while for log g = 0.0 we find Teff = 4700 K, and a comparison with template stellar spectra provides Teff ˜ 4500 K. The observed spectral energy distribution (SED), and the intensities of the emission lines, vary on short (≲1 d) time-scales, due to disc variability. We invoke a simple one-component model for the accretion disc, and a model with a hot boundary layer, with high (˜3.9 × 10-6 M⊙ yr-1) and low (˜2 × 10-8 M⊙ yr-1) accretion rates, respectively. Fits to the accretion disc-extracted infrared spectrum (2008 July 15) yield effective temperatures for the red giant of {T_eff}= 3800 ± 100 K (log g = 2.0) and {T_eff}= 3700 ± 100 K (log g = 0.0). Furthermore, using a more sophisticated approach, we reproduced the optical and infrared SEDs of the red giant in the RS Oph system with a two-component model atmosphere, in which 90 per cent of the surface has Teff = 3600 K and 10 per cent has Teff = 5000 K. Such structure could be due to irradiation of the red giant by the white dwarf.

  20. Space station image captures a red tide ciliate bloom at high spectral and spatial resolution

    PubMed Central

    Dierssen, Heidi; McManus, George B.; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

    2015-01-01

    Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (106 cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity. PMID:26627232

  1. Space station image captures a red tide ciliate bloom at high spectral and spatial resolution.

    PubMed

    Dierssen, Heidi; McManus, George B; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

    2015-12-01

    Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (10(6) cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity. PMID:26627232

  2. Self-similar spectral structures and edge-locking hierarchy in open-boundary spin chains

    SciTech Connect

    Haque, Masudul

    2010-07-15

    For an anisotropic Heisenberg (XXZ) spin chain, we show that an open boundary induces a series of approximately self-similar features at different energy scales, high up in the eigenvalue spectrum. We present a nonequilibrium phenomenon related to this fractal structure, involving states in which a connected block near the edge is polarized oppositely to the rest of the chain. We show that such oppositely polarized blocks can be 'locked' to the edge of the spin chain and that there is a hierarchy of edge-locking effects at various orders of the anisotropy. The phenomenon enables dramatic control of quantum-state transmission and magnetization control.

  3. [Impacts of different alkaline soil on canopy spectral characteristics of overlying vegetation].

    PubMed

    Jia, Ke-Li; Zhang, Jun-Hua

    2014-03-01

    The relationship between alkalinity and pH of the soil, reflectance spectra and red-edge parameters of the sunflower canopy in different growth periods under different alkalinity soil were analyzed, respectively. The results showed that the spectral reflectance of the sunflower canopy in different stage under different alkalinity soil is the same as the spectral reflectance characters of the other greenery canopy. Along with the advancement of the sunflower growth period, sunflower canopy spectral reflectance increases gradually at different stages, the spectral reflectance is higher at flowering stage than 7-leaf stage and budding stage, and there exists a high reflection peak at 809nm at flowering period. At the same time, the spectral reflectance is affected by salinity-alkalinity stress at different stages, in the near infrared shortwave band, the spectral reflectance of the sunflower canopy in different stage increases with the decreases in soil alkalinity. When the derivatives are applied to determine the wavelength of the red-edge, there is a shift phenomenon of the red edge. The red edges were at 702-720 nm during every growth period of the sunflower. The "blue shift" phenomenon is also emerged for red edge position and red edge sloped with the increase in the soil alkalinity. Conversely, at the same growth periods, the red edge positions and red edge slope move to longer wave bands with the decrease in soil alkalinity. There is a "red shift" phenomenon before flowering period and "blue shift" phenomenon after flowering period for the red edge position and red edge slope of canopy spectrum at the same soil alkalinity. Respectively. The red edges at different growth stages of the sunflower show very significant positive correlation and quadratic polynomial to alkalinity and pH of the soil. Therefore, we thought used the red edge features of greenery could indicate the soil alkalization degree, it providing scientific basis for monitoring soil alkalization

  4. Integration of environmental and spectral data for sunflower stress determination. [Red River Valley, Minnesota

    NASA Technical Reports Server (NTRS)

    Lillesand, T.; Seeley, M.

    1983-01-01

    Stress in sunflowers was assessed in western and northwestern Minnesota. Weekly ground observations (acquired in 1980 and 1981) were analyzed in concert with large scale aerial photography and concurrent LANDSAT data. Using multidate supervised and unsupervised classification procedures, it was found that all crops grown in association with sunflowers in the study area are spectrally separable from one another. Under conditions of extreme drought, severely stressed plants were differentiable from those not severely stressed, but between-crop separation was not possible. Initial regression analyses to estimate sunflower seed yield showed a sensitivity to environmental stress during the flowering and seed development stages. One of the most important biological factors related to sunflower production in the Red River Valley area was found to be the extent and severity of insect infestations.

  5. Evolution of the stellar-merger red nova V1309 Scorpii: Spectral energy distribution analysis

    NASA Astrophysics Data System (ADS)

    Tylenda, R.; Kamiński, T.

    2016-08-01

    Context. One very important object for understanding the nature of red novae is V1309 Sco. Its pre-outburst observations showed that, before its red-nova eruption in 2008, it was a contact binary quickly evolving to the merger of the components. It thus provided us with a direct evidence that the red novae result from stellar mergers. Aims: We will study the evolution of the post-merger remnant of V1309 Sco over time. Methods: We analyse the spectral energy distribution (SED) of the object and its evolution with time. From various optical and infrared surveys and observing programmes carried out with OGLE, HST, VVV, Gemini South, WISE, Spitzer, and Herschel we constructed observed SED in 2010 and 2012. Some limited data are also available for the red-nova progenitor in 2007. We analyse the data with our model of a dusty envelope surrounding a central star. Results: Dust was present in the pre-outburst state of V1309 Sco. Its high temperature (900-1000 K) suggests that this was a freshly formed dust in a presumable mass-loss from the spiralling-in binary. Shortly after its 2008 eruption, V1309 Sco became almost completely embedded in dust. The parameters (temperature, dimensions) of the dusty envelope in 2010 and 2012 evidence that we then observed matter lost by the object during the 2008 outburst. Its mass is at least 10-3M⊙. The object remains quite luminous, although since its maximum brightness in September 2008, it has faded in luminosity by a factor of ~50 (in 2012). Far infrared data from Herschel reveal presence of a cold (~30 K) dust at a distance of a few thousand AU from the object. Conclusions: Similarly to other red novae, V1309 Sco formed a slowly-expanding, dense, and optically-thick dusty envelope during its 2008 outburst. The main remnant is thus hidden for us. Far infrared data suggests that the object passed an episode of intense mass loss in its recent history. This conclusion could be verified by submillimeter interferometric observations.

  6. Use of IRS-P4 Ocean Color Monitor (OCM) images for tracing the red edge of the terrestrial vegetation reflectance spectrum

    NASA Astrophysics Data System (ADS)

    Raychaudhuri, B.

    2016-04-01

    A methodology is put forward to retrieve the red edge for terrestrial vegetated regions of IRS P4 Ocean Color Monitor (OCM) images. The objective is to utilize land-related portions of the archived OCM images that contain a significant amount of digital information on land cover. OCM band data were simulated from spectroradiometric reflectance of fresh green leaves and hyperspectral reflectance of vegetated regions derived from EO-1 Hyperion images. The red edge recovered from these model data using numerical techniques of Lagrange interpolation and inverted Gaussian was compared with the original one and reasonable accuracy was obtained. The technique was then applied to the actual red and near-infrared bands of OCM images, and red edge reflectance curves were computed for evergreen, deciduous and mangrove forest regions of the images for winter and spring seasons. Consistent results were obtained for seasonal changes, and vegetated and non-vegetated areas could be distinguished.

  7. Effects of spectral parameters on the light properties of red-green-blue white light-emitting diodes.

    PubMed

    Xu, Mingsheng; Zhang, Haoxiang; Zhou, Quanbin; Wang, Hong

    2016-06-01

    Red-green-blue white light-emitting diodes (RGB-WLEDs) have great potential as commercial solid-state lighting devices, as well as visible light communication because of their high color-rendering index (CRI) and high response frequency. The quality of light of an RGB-WLED strongly depends on its spectral parameters. In this study, we fabricated RGB-WLEDs with red, blue, and green LEDs and measured the spectral power distribution (SPD). The experimental SPD is consistent with the calculated spectrum. We also measured the SPDs of LEDs with different peak wavelengths and extracted the spectral parameters, which were then used for modeling. We studied the effect of the wavelength and the full width at half-maximum (FWHM) on both the color rendering index and the luminous efficiency (LE) of the RGB-WLED using simulations. We find that the LE improves as the wavelength of the blue LED increases and the wavelength of the red LED decreases. When the wavelength of the green LED increases, the LE increases first, but later decreases. The CRI of the RGB-WLED increases with the wavelengths of the red, blue, and green LEDs first, but then decreases. The optimal wavelengths and FWHMs for maximum color-rendering and LE of the blue, green, and red LEDs are 466, 536, 606 nm; and 26.0, 34.0, and 19.5 nm, respectively. PMID:27411203

  8. Spectral sensitivity of the photointrinsic iris in the red-eared slider turtle (Trachemys scripta elegans).

    PubMed

    Sipe, Grayson O; Dearworth, James R; Selvarajah, Brian P; Blaum, Justin F; Littlefield, Tory E; Fink, Deborah A; Casey, Corinne N; McDougal, David H

    2011-01-01

    Our goal in this study was to examine the red-eared slider turtle for a photomechanical response (PMR) and define its spectral sensitivity. Pupils of enucleated eyes constricted to light by ∼11%, which was one-third the response measured in alert behaving turtles at ∼33%. Rates of constriction in enucleated eyes that were measured by time constants (1.44-3.70 min) were similar to those measured in turtles at 1.97 min. Dilation recovery rates during dark adaptation for enucleated eyes were predicted using line equations and computed times for reaching maximum sizes between 26 and 44 min. Times were comparable to the measures in turtles where maximum pupil size occurred within 40 min and possessed a time constant of 12.78 min. Hill equations were used to derive irradiance threshold values from enucleated hemisected eyes and then plot a spectral sensitivity curve. The analysis of the slopes and maximum responses revealed contribution from at least two different photopigments, one with a peak at 410 nm and another with a peak at 480 nm. Fits by template equations suggest that contractions are triggered by multiple photopigments in the iris including an opsin-based visual pigment and some other novel photopigment, or a cryptochrome with an absorbance spectrum significantly different from that used in our model. In addition to being regulated by retinal feedback via parasympathetic nervous pathways, the results support that the iris musculature is photointrinsically responsive. In the turtle, the control of its direct pupillary light response (dPLR) includes photoreceptive mechanisms occurring both in its iris and in its retina. PMID:20951155

  9. Spectral Gap and Edge Excitations of d-Dimensional PVBS Models on Half-Spaces

    NASA Astrophysics Data System (ADS)

    Bishop, Michael; Nachtergaele, Bruno; Young, Amanda

    2016-03-01

    We analyze a class of quantum spin models defined on half-spaces in the d-dimensional hypercubic lattice bounded by a hyperplane with inward unit normal vector min {R}^d. The family of models was previously introduced as the single species Product Vacua with Boundary States (PVBS) model, which is a spin-1/2 model with a XXZ-type nearest neighbor interactions depending on parameters λ _jin (0,∞), one for each coordinate direction. For any given values of the parameters, we prove an upper bound for the spectral gap above the unique ground state of these models, which vanishes for exactly one direction of the normal vector m. For all other choices of m we derive a positive lower bound of the spectral gap, except for the case λ _1 =\\cdots =λ _d=1, which is known to have gapless excitations in the bulk.

  10. Spectral Invariant Behavior of Zenith Radiance Around Cloud Edges Observed by ARM SWS

    NASA Technical Reports Server (NTRS)

    Marshak, A.; Knyazikhin, Y.; Chiu, J. C.; Wiscombe, W. J.

    2009-01-01

    The ARM Shortwave Spectrometer (SWS) measures zenith radiance at 418 wavelengths between 350 and 2170 nm. Because of its 1-sec sampling resolution, the SWS provides a unique capability to study the transition zone between cloudy and clear sky areas. A spectral invariant behavior is found between ratios of zenith radiance spectra during the transition from cloudy to cloud-free. This behavior suggests that the spectral signature of the transition zone is a linear mixture between the two extremes (definitely cloudy and definitely clear). The weighting function of the linear mixture is a wavelength-independent characteristic of the transition zone. It is shown that the transition zone spectrum is fully determined by this function and zenith radiance spectra of clear and cloudy regions. An important result of these discoveries is that high temporal resolution radiance measurements in the clear-to-cloud transition zone can be well approximated by lower temporal resolution measurements plus linear interpolation.

  11. Spectral relationships for atmospheric correction. II. Improving NASA's standard and MUMM near infra-red modeling schemes.

    PubMed

    Goyens, C; Jamet, C; Ruddick, K G

    2013-09-01

    Spectral relationships, reflecting the spectral dependence of water-leaving reflectance, ρw(λ), can be easily implemented in current AC algorithms with the aim to improve ρw(λ) retrievals where the algorithms fail. The present study evaluates the potential of spectral relationships to improve the MUMM [Ruddick et al., 2006, Limnol. Oceanogr. 51, 1167-1179] and standard NASA [Bailey et al., 2010, Opt. Express 18, 7521-7527] near infra-red (NIR) modeling schemes included in the AC algorithm to account for non-zero ρw(λNIR), based on in situ coastal ρw(λ) and simulated Rayleigh corrected reflectance data. Two modified NIR-modeling schemes are investigated: (1) the standard NASA NIR-modeling scheme is forced with bounding relationships in the red spectral domain and with a NIR polynomial relationship and, (2) the constant NIR ρw(λ) ratio used in the MUMM NIR-modeling scheme is replaced by a NIR polynomial spectral relationship. Results suggest that the standard NASA NIR-modeling scheme performs better for all turbidity ranges and in particular in the blue spectral domain (percentage bias decreased by approximately 50%) when it is forced with the red and NIR spectral relationships. However, with these new constraints, more reflectance spectra are flagged due to non-physical Chlorophyll-a concentration estimations. The new polynomial-based MUMM NIR-modeling scheme yielded lower ρw(λ) retrieval errors and particularly in extremely turbid waters. However, including the polynomial NIR relationship significantly increased the sensitivity of the algorithm to errors on the selected aerosol model from nearby clear water pixels. PMID:24103991

  12. The first step in vision occurs in femtoseconds: complete blue and red spectral studies.

    PubMed Central

    Peteanu, L A; Schoenlein, R W; Wang, Q; Mathies, R A; Shank, C V

    1993-01-01

    Femtosecond transient absorption measurements of the cis-trans isomerization of the visual pigment rhodopsin clarify the interpretation of the dynamics of the first step in vision. We present femtosecond time-resolved spectra as well as kinetic measurements at specific wavelengths between 490 and 670 nm using 10-fs probe pulses centered at 500 and 620 nm following a 35-fs pump pulse at 500 nm. The expanded spectral window beyond that available (500-570 nm) in our previous study [Schoenlein, R. W., Peteanu, L. A., Mathies, R. A. & Shank, C. V. (1991) Science 254, 412-415] provides the full differential absorption spectrum of the photoproduct as a function of delay time after photolysis. The high time-resolution data presented here contradict an alternative interpretation of the rhodopsin photochemistry offered by Callender and co-workers [Yan, M., Manor, D., Weng, G., Chao, H., Rothberg, L., Jedju, T. M., Alfano, R. R. & Callender, R. H. (1991) Proc. Natl. Acad. Sci. USA 88, 9809-9812]. Our results confirm that the red-shifted (lambda max approximately 570 nm) photo-product of the isomerization reaction is fully formed within 200 fs. Subsequent changes in the differential spectra between 200 fs and 6 ps are attributed to a combination of dynamic ground-state processes such as intramolecular vibrational energy redistribution, vibrational cooling, and conformational relaxation. Images Fig. 2 PMID:8265623

  13. Detecting cycles in stratigraphic data: Spectral analysis in the presence of red noise

    NASA Astrophysics Data System (ADS)

    Vaughan, S.; Bailey, R. J.; Smith, D. G.

    2011-12-01

    We discuss the detection of cyclic signals in stratigraphic `time series' using spectral methods. The dominant source of variance in the stratigraphic record is red noise, which greatly complicates the process of searching for weak periodic signals. We highlight two issues that are more significant than generally appreciated. The first is the lack of a correction for `multiple tests' - many independent frequencies are examined for periods but using a significance test appropriate for examination of a single frequency. The second problem is the poor choice of null hypothesis used to model the spectrum of non-periodic variations. Stratigraphers commonly assume the noise is a first-order autoregressive process - the AR(1) model - which in practice often gives a very poor match to real data; a fact that goes largely unnoticed because model checking is rarely performed. These problems have the effect of raising the number of false positives far above the expected rate, to the extent that the literature on spatial stratigraphic cycles is dominated by false positives. In turn these will distort the construction of astronomically calibrated timescales, lead to inflated estimates of the physical significance of deterministic forcing of the climate and depositional processes in the pre-Neogene, and may even bias models of solar system dynamics on very long timescales. We make suggestions for controlling the false positive rate, and emphasize the value of Monte Carlo simulations to validate and calibrate analysis methods.

  14. Primer on Use of Multi-Spectral and Infra Red Imaging for On-Site Inspections

    SciTech Connect

    Henderson, J R

    2010-10-26

    The purpose of an On-Site Inspection (OSI) is to determine whether a nuclear explosion has occurred in violation of the Comprehensive Nuclear Test Ban Treaty (CTBT), and to gather information which might assist in identifying the violator (CTBT, Article IV, Paragraph 35) Multi-Spectral and Infra Red Imaging (MSIR) is allowed by the treaty to detect observables which might help reduce the search area and thus expedite an OSI and make it more effective. MSIR is permitted from airborne measurements, and at and below the surface to search for anomalies and artifacts (CTBT, Protocol, Part II, Paragraph 69b). The three broad types of anomalies and artifacts MSIR is expected to be capable of observing are surface disturbances (disturbed earth, plant stress or anomalous surface materials), human artifacts (man-made roads, buildings and features), and thermal anomalies. The purpose of this Primer is to provide technical information on MSIR relevant to its use for OSI. It is expected that this information may be used for general background information, to inform decisions about the selection and testing of MSIR equipment, to develop operational guidance for MSIR use during an OSI, and to support the development of a training program for OSI Inspectors. References are provided so readers can pursue a topic in more detail than the summary information provided here. The following chapters will provide more information on how MSIR can support an OSI (Section 2), a short summary what Multi-Spectral Imaging and Infra Red Imaging is (Section 3), guidance from the CTBT regarding the use of MSIR (Section 4), and a description of several nuclear explosion scenarios (Section 5) and consequent observables (Section 6). The remaining sections focus on practical aspects of using MSIR for an OSI, such as specification and selection of MSIR equipment, operational considerations for deployment of MISR equipment from an aircraft, and the conduct of field exercises to mature MSIR for an OSI

  15. Observation of the "Red Edge" Effect in the Luminescence of Water Suspensions of Detonation Nanodiamonds

    NASA Astrophysics Data System (ADS)

    Dolenko, T. A.; Burikov, S. A.; Vervald, A. M.; Khomich, A. A.; Kudryavtsev, O. S.; Shenderova, O. A.; Vlasov, I. I.

    2016-05-01

    The variations in the luminescence spectra of detonation nanodiamond (DND) with probe light wavelength are studied and these dependences are compared for water suspensions of DND and graphene oxide (GO). It is found that changing the laser excitation wavelength from 405 to 532 nm shifts the broad-band luminescence peaks of DND and GO from 530 to 615 nm and from 490 to 580 nm. The observed dependences are explained by the luminescence ″red edge″ effect, which shows up when the electrostatic interaction (solvation) times of a luminophore with a polar solvent are comparable to the luminescence lifetime. These data confirm the common origin of luminescence in nanodiamonds and oxidized graphene nanoclusters.

  16. Why is the Great Red Spot Red? The Exogenic, Photolytic Origin of the UV/Blue-Absorbing Chromophores of Jupiter’s Great Red Spot as Determined by Spectral Analysis of Cassini/VIMS Observations using New Laboratory Optical Coefficients

    NASA Astrophysics Data System (ADS)

    Baines, Kevin H.; Carlson, Robert W.; Momary, Thomas W.

    2014-11-01

    For centuries, a major question for Jupiter has been: Why is the Great Red Spot red? In particular, two major theories have been proposed: (1) that the coloring is due to photolytic processes in the upper cloud layer, or (2) it is due to the upwellimg of red materials processed relatively deep within the troposphere. Utilizing indices of refraction for red choromophores generated by the photolysis of ammonia and acetylene in the laboratory, we present results of a spectral analysis of the core of Jupiter’s Great Red Spot (GRS) as observed by the visual channel of the Cassini/Visual Infrared Mapping Spectrometer (VIMS). Consistent with the physical origin of such laboratory-generated chromophores in Jupiter - i.e., by solar-driven UV photolysis within the upper levels of the GRS structure near ~ 0.3 bar - our spectral modeling yields satisfactory results for such Mie scattering chromophores only when they are confined to the upper ~ 100 mbar of the GRS. Beneath this reddish upper cloud layer, our models indicate that the remainder of the GRS cloud - assumed to extend down to at least the ammonia condensation level near 0.6 bar - must be relatively spectrally bright throughout the UV-red spectrum; that is, they must be predominantly a whitish or grey color at depth. Thus, our 0.35-1.0 micron spectral models of the GRS are inconsistent with an endogenic origin of the reddish coloring originating in the depths of Jupiter, but are consistent with a photolytic origin due to the photolysis of ammonia and acetylene in the upper troposphere.

  17. Effect of Spectral Transmittance through Red-Tinted Rodent Cages on Circadian Metabolism and Physiology in Nude Rats

    PubMed Central

    Dauchy, Robert T; Wren, Melissa A; Dauchy, Erin M; Hanifin, John P; Jablonski, Michael R; Warfield, Benjamin; Brainard, George C; Hill, Steven M; Mao, Lulu; Dupepe, Lynell M; Ooms, Tara G; Blask, David E

    2013-01-01

    Light entrains normal circadian rhythms of physiology and metabolism in all mammals. Previous studies from our laboratory demonstrated that spectral transmittance (color) of light passing through cages affects these responses in rats. Here, we addressed the hypothesis that red tint alters the circadian nocturnal melatonin signal and circadian oscillation of other metabolic and physiologic functions. Female nude rats (Hsd:RH-Foxn1rnu; n = 12 per group) were maintained on a 12:12-h light (300 lx; 123.0 μW/cm2; lights on 0600):dark regimen in standard polycarbonate translucent clear or red-tinted cages. After 1 wk, rats underwent 6 low-volume blood draws via cardiocentesis over a 4-wk period. Plasma melatonin levels were low during the light phase (1.0 ± 0.2 pg/mL) in rats in both types of cages but were significantly lower in red-tinted (105.0 ± 2.4 pg/mL) compared with clear (154.8 ± 3.8 pg/mL) cages during the dark. Normal circadian rhythm of plasma total fatty acid was identical between groups. Although phase relationships of circadian rhythms in glucose, lactic acid, pO2, and pCO2 were identical between groups, the levels of these analytes were lower in rats in red-tinted compared with clear cages. Circadian rhythms of plasma corticosterone, insulin, and leptin were altered in terms of phasing, amplitude, and duration in rats in red-tinted compared with clear cages. These findings indicate that spectral transmittance through red-colored cages significantly affects circadian regulation of neuroendocrine, metabolic, and physiologic parameters, potentially influencing both laboratory animal health and wellbeing and scientific outcomes. PMID:24351763

  18. The Relationship of Red and Photographic Infrared Spectral Data to Grain Yield Variation Within a Winter Wheat Field

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.; Holben, B. N.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

    1979-01-01

    Two band hand-held radiometer data from a winter wheat field, collected on 21 dates during the spring growing season, were correlated within field final grain yield. Significant linear relationships were found between various combinations of the red and photographic infrared radiance data collected and the grain yield. The spectral data explained approximately 64 percent of the within field grain yield variation. This variation in grain yield could not be explained using meteorological data as these were similar for all areas of the wheat field. Most importantly, data collected early in the spring were highly correlated with grain yield, a five week time window existed from stem elongation through antheses in which the spectral data were most highly correlated with grain yield, and manifestations of wheat canopy water stress were readily apparent in the spectral data.

  19. The dynamic atmospheres of red giant stars. Spectral synthesis in high resolution

    NASA Astrophysics Data System (ADS)

    Nowotny, W.

    2005-11-01

    giant stars generally have extremely extended atmospheres with extensions on the same order as the radii of the stars themselves (a few 100 R_sol). Within these cool and relatively dense environments, molecules can efficiently form. They have many internal degrees of freedom leading to a large number of possible transitions (electronic, vibrational, and rotational) and numerous absorption lines/bands. Thus, molecules significantly determine the spectral appearance of late-type stars which have characteristic line-rich spectra in the visual and infrared. At the upper part of the AGB, the stars become unstable to strong radial pulsations (e.g. Mira variables). Due to the large size variations of the stellar interior, the outer layers are levitated and the atmospheric structure is periodically modulated. Triggered by the pulsation, shock waves emerge and propagate outwards through the atmosphere. Efficient dust condensation can take place in the wake of the shock waves ( post-shock regions). Due to the large absorptivity of the formed dust grains, radiation pressure results in an outwards directed acceleration with the outflowing dust particles dragging along the surrounding gas. This leads to the development of a rather slow but dense stellar wind. The just mentioned dynamic effects -- pulsations of the stellar interior and dust-driven winds -- have substantial influence on the evolution of the outer layers of these red giants. As a consequence, the atmospheres of evolved AGB stars can eventually become even more extended. Being time-dependently changed on global and local scales, the resulting atmospheric structure strongly deviates from a hydrostatic configuration (e.g. shock fronts). Especially important in the context of this thesis are the complex, non-monotonic velocity fields with macroscopic motions on the order of 10 km/s, severly affecting the shapes of individual spectral lines (Doppler effect). Observational studies have demonstrated that time series high

  20. CHEMICAL ABUNDANCES IN FIELD RED GIANTS FROM HIGH-RESOLUTION H-BAND SPECTRA USING THE APOGEE SPECTRAL LINELIST

    SciTech Connect

    Smith, Verne V.; Cunha, Katia; Shetrone, Matthew D.; Meszaros, Szabolcs; Allende Prieto, Carlos; Bizyaev, Dmitry; Garcia Perez, Ana; Majewski, Steven R.; Schiavon, Ricardo; Holtzman, Jon; Johnson, Jennifer A.

    2013-03-01

    High-resolution H-band spectra of five bright field K, M, and MS giants, obtained from the archives of the Kitt Peak National Observatory Fourier transform spectrometer, are analyzed to determine chemical abundances of 16 elements. The abundances were derived via spectrum synthesis using the detailed linelist prepared for the Sloan Digital Sky Survey III Apache Point Galactic Evolution Experiment (APOGEE), which is a high-resolution near-infrared spectroscopic survey to derive detailed chemical abundance distributions and precise radial velocities for 100,000 red giants sampling all Galactic stellar populations. The red giant sample studied here was chosen to probe which chemical elements can be derived reliably from the H-band APOGEE spectral region. These red giants consist of two K-giants ({alpha} Boo and {mu} Leo), two M-giants ({beta} And and {delta} Oph), and one thermally pulsing asymptotic giant branch (TP-AGB) star of spectral type MS (HD 199799). Measured chemical abundances include the cosmochemically important isotopes {sup 12}C, {sup 13}C, {sup 14}N, and {sup 16}O, along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The K and M giants exhibit the abundance signature of the first dredge-up of CN-cycle material, while the TP-AGB star shows clear evidence of the addition of {sup 12}C synthesized during {sup 4}He-burning thermal pulses and subsequent third dredge-up. A comparison of the abundances derived here with published values for these stars reveals consistent results to {approx}0.1 dex. The APOGEE spectral region and linelist is thus well suited for probing both Galactic chemical evolution, as well as internal nucleosynthesis and mixing in populations of red giants via high-resolution spectroscopy.

  1. Flow injection mass spectral fingerprints demonstrate chemical differences in rio red grapefruit with respect to year, harvest time, and conventional versus organic farming

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectral fingerprints were acquired for Ruby Red grapefruit using direct injection-electrospray ionization with time-of-flight and ion trap mass spectrometry (DI-ESI-TOF-MS and DI-ESI-IT-MS). Rio Red grapefruits were harvested 3 times a year (early, mid, and late harvests) in 2005 and 2006 from con...

  2. Relationship of red and photographic infrared spectral radiances to alfalfa biomass, forage water content, percentage canopy cover, and severity of drought stress

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

    1979-01-01

    Red and photographic infrared spectral data were collected using a handheld radiometer for two cuttings of alfalfa. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover for the earlier alfalfa cutting. The alfalfa of later cutting experienced a period of severe drought stress which limited growth. The spectral variables were found to be highly correlated with the estimated drought scores for this alfalfa cutting.

  3. The red edge excitation shift phenomenon can be used to unmask protein structural ensembles: implications for NEMO-ubiquitin interactions.

    PubMed

    Catici, Dragana A M; Amos, Hope E; Yang, Yi; van den Elsen, Jean M H; Pudney, Christopher R

    2016-06-01

    To understand complex molecular interactions, it is necessary to account for molecular flexibility and the available equilibrium of conformational states. Only a small number of experimental approaches can access such information. Potentially steady-state red edge excitation shift (REES) spectroscopy can act as a qualitative metric of changes to the protein free energy landscape (FEL) and the equilibrium of conformational states. First, we validate this hypothesis using a single Trp-containing protein, NF-κB essential modulator (NEMO). We provide detailed evidence from chemical denaturation studies, macromolecular crowding studies, and the first report of the pressure dependence of the REES effect. Combination of these data demonstrate that the REES effect can report on the 'ruggedness' of the FEL and we present a phenomenological model, based on realistic physical interpretations, for fitting steady-state REES data to allow quantification of this aspect of the REES effect. We test the conceptual framework we have developed by correlating findings from NEMO ligand-binding studies with the REES data in a range of NEMO-ligand binary complexes. Our findings shed light on the nature of the interaction between NEMO and poly-ubiquitin, suggesting that NEMO is differentially regulated by poly-ubiquitin chain length and that this regulation occurs via a modulation of the available equilibrium of conformational states, rather than gross structural change. This study therefore demonstrates the potential of REES as a powerful tool for tackling contemporary issues in structural biology and biophysics and elucidates novel information on the structure-function relationship of NEMO and key interaction partners. PMID:27028374

  4. Limitations and design considerations for donor–acceptor systems in luminescent solar concentrators: the effect of coupling-induced red-edge absorption

    NASA Astrophysics Data System (ADS)

    MacQueen, Rowan W.; Tayebjee, Murad J. Y.; Webb, James E. A.; Falber, Alexander; Thordarson, Pall; Schmidt, Timothy W.

    2016-06-01

    Luminescent solar concentrators (LSCs) use luminescence and waveguiding to concentrate photons within thin dielectric slabs for use in photovoltaic, lighting, and photobioreactor applications. Donor–acceptor systems of organic chromophores are widely used in LSCs to broaden the sunlight absorption range and attempt to reduce loss-inducing reabsorption by the emitting chromophore. We use raytrace simulations across a large parameter space to model the performance of LSCs containing two novel donor–acceptor trimers based on the perylene moiety. We find that under certain conditions, trimers outperform single-dye LSCs as expected. However, at higher concentrations, a slight increase in red-edge absorption by the trimers increases reabsorption and has a deleterious effect on LSC performance. This underscores the large effect that even small changes in the red edge can have, and may discourage the use of donor–acceptor schemes with high interchromophore coupling that promotes red-edge absorption. Finally, we show that for a LSC-PV pair, selecting a PV cell that is well-matched with the LSC emission spectrum has a large effect on the flux gain of the system, and that the systems studied here are well-matched to emerging PV technologies.

  5. Spectral correlates of a quasi-stable depolarization in barnacle photoreceptor following red light.

    PubMed

    Brown, H M; Cornwall, M C

    1975-07-01

    1. Illumination of B. eburneus photoreceptors with intense red light produces a membrane depolarization that persists in darkness. This quasistable depolarization (latch-up) can be terminated with green light. The phenomenon was investigated with electrophysiological, spectrochemical, and microspectrophotometric techniques. 2. Latch-up was associated with a stable inward current in cells with the membrane potential voltage-clamped at the resting potential in darkness. The stable current could only be elicited at wave-lengths greater than 580 nm. 3. Light-induced current (LIC) was measured at various wave-lengths in dark-adapted photoreceptors with the membrane voltage-clamped to the resting potential. The minimum number of photons required to elicit a fixed amount of LIC occurred at 540 nm, indicating that the photoreceptor is maximally sensitive to this wave-length of light. The photoreceptor was also sensitive to wave-lengths in the near-U.V. region of the spectrum (380-420 nm). 4. Steady red adapting light reduced the magnitude of the LIC uniformly at all wave-lengths except in the near-U.V. region of the spectrum; sensitivity was reduced less in this region. 5. The spectrum for termination of the stable inward current following or during red light was shifted to the blue (peak about 510 nm) compared to the peak for LIC (peak about 540 nm). 6. Absorbance of single cells prepared under bright, red light decreased maximally at 480 nm following exposure to wave-lengths of light longer than 540 nm. 7. A pigment extract of 1000 barnacle ocelli prepared under dim, red light had a maximum absorbance change at 480 nm when bleached with blue-gree light. 8. There was no evidence in the latter two experiments of photointerconversion of pigments with absorbance maxima at 480 and 540 nm. Rather, the maximum absorption of the bleaching products seemed to occur at wave-lengths shorter than 420 nm. 9. Since latch-up induction occurs at wave-lengths longer than 580 nm, it may

  6. High-spectral-radiance, red-emitting tapered diode lasers with monolithically integrated distributed Bragg reflector surface gratings.

    PubMed

    Feise, David; John, Wilfred; Bugge, Frank; Fiebig, Christian; Blume, Gunnar; Paschke, Katrin

    2012-10-01

    A red-emitting tapered diode laser with a monolithically integrated distributed Bragg reflector grating is presented. The device is able to emit up to 1 W of spectrally stabilized optical output power at 5°C. Depending on the period of the tenth order surface grating the emission wavelengths of these devices from the same gain material are 635 nm, 637 nm, and 639 nm. The emission is as narrow as 9 pm (FWHM) at 637.6 nm. The lateral beam quality is M(2)(1/e(2)) = 1.2. Therefore, these devices simplify techniques such as wavelength multiplexing and fiber coupling dedicating them as light sources for µ-Raman spectroscopy, absolute distance interferometry, and holographic imaging. PMID:23188301

  7. Stress assessment and spectral characterization of suspected acid deposition damage in red spruce (Picea Rubens) from Vermont

    NASA Technical Reports Server (NTRS)

    Rock, B. N.; Vogelmann, J. E.

    1985-01-01

    The effects of acid deposition on Picea rubens are studied. The Picea rubens located at Camels Hump Mt., Mt. Ascutney, and Ripton, VT were analyzed using stress level evaluations, in situ spectral data, pressure bomb analysis, and aircraft sensors. Spruce stress per circular plot and percent spruce mortality are calculated. The relation between stress levels and elevation and exposure and weather patterns is examined. It is observed that variations in the reflectance curves of the foliage and branches are related to cellular health, the type of cellular arrangement, and the degree of leaf tissue hydration; the leaf and twig specimens from high stress sites are more reflective in the red portion of the visible and less reflective in the NIR portion of the spectrum. The pressure bomb data reveal that the xylem water tension is higher in specimens from high stress sites. It is noted that remote sensing permits discrimination and mapping of suspected acid deposition damage.

  8. Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea.

    PubMed

    Eyal, Gal; Wiedenmann, Jörg; Grinblat, Mila; D'Angelo, Cecilia; Kramarsky-Winter, Esti; Treibitz, Tali; Ben-Zvi, Or; Shaked, Yonathan; Smith, Tyler B; Harii, Saki; Denis, Vianney; Noyes, Tim; Tamir, Raz; Loya, Yossi

    2015-01-01

    The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50-60 m at the Interuniversity Institute for Marine Sciences (IUI) reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40-100 m). Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging. PMID:26107282

  9. Spectral Diversity and Regulation of Coral Fluorescence in a Mesophotic Reef Habitat in the Red Sea

    PubMed Central

    Eyal, Gal; Wiedenmann, Jörg; Grinblat, Mila; D’Angelo, Cecilia; Kramarsky-Winter, Esti; Treibitz, Tali; Ben-Zvi, Or; Shaked, Yonathan; Smith, Tyler B.; Harii, Saki; Denis, Vianney; Noyes, Tim; Tamir, Raz; Loya, Yossi

    2015-01-01

    The phenomenon of coral fluorescence in mesophotic reefs, although well described for shallow waters, remains largely unstudied. We found that representatives of many scleractinian species are brightly fluorescent at depths of 50–60 m at the Interuniversity Institute for Marine Sciences (IUI) reef in Eilat, Israel. Some of these fluorescent species have distribution maxima at mesophotic depths (40–100 m). Several individuals from these depths displayed yellow or orange-red fluorescence, the latter being essentially absent in corals from the shallowest parts of this reef. We demonstrate experimentally that in some cases the production of fluorescent pigments is independent of the exposure to light; while in others, the fluorescence signature is altered or lost when the animals are kept in darkness. Furthermore, we show that green-to-red photoconversion of fluorescent pigments mediated by short-wavelength light can occur also at depths where ultraviolet wavelengths are absent from the underwater light field. Intraspecific colour polymorphisms regarding the colour of the tissue fluorescence, common among shallow water corals, were also observed for mesophotic species. Our results suggest that fluorescent pigments in mesophotic reefs fulfil a distinct biological function and offer promising application potential for coral-reef monitoring and biomedical imaging. PMID:26107282

  10. Photoelectric spectrophotometry of OQ 172 and OH 471. [spectral energy distributions for red shift quasars

    NASA Technical Reports Server (NTRS)

    Oke, J. B.

    1974-01-01

    Absolute spectral energy distributions for the large redshift quasars OQ 172 and OH 471 are discussed along with similar data for two other quasars 4C05.34 and PHL 957. Assuming cosmological redshifts, OQ 172 and OH 471 are not as luminous as PHL 957. If these quasars are basically similar and if radiative processes dominate, the strength of Ly alpha and the behavior of the continuum at the Lyman limit strongly suggest that these objects consist of a central ionizing source surrounded by discrete clouds, filaments or a gaseous structure such as a disk. This gaseous matter does not cover the whole solid angle surrounding the source.

  11. Broadband beamsplitter for high intensity laser applications in the infra-red spectral range.

    PubMed

    Amotchkina, Tatiana; Fattahi, Hanieh; Pervak, Yurij A; Trubetskov, Michael; Pervak, Vladimir

    2016-07-25

    We report on design, production and characterization of an extremely broadband multilayer beamsplitter, covering wavelength range from 0.67 - 2.6 µm. The group delay dispersion has small oscillations in the above mentioned working range. We used a new algorithm with floating constants allowing us to obtain a smooth and near constant GDD. The optical element based on the beamsplitter is used for dividing a low-energy super-octave spectrum into several sub-spectral regions which are later amplified and coherently combined. PMID:27464129

  12. Inclusion complex of Alizarin Red S with β-cyclodextrin: Synthesis, spectral, electrochemical and computational studies

    NASA Astrophysics Data System (ADS)

    Chin, Yuk Ping; Abdul Raof, Siti Farhana; Sinniah, Subathra; Lee, Vannajan Sanghiran; Mohamad, Sharifah; Abdul Manan, Ninie Suhana

    2015-03-01

    Inclusion complex formation of Alizarin Red S (ARS) with β-cyclodextrin was studied by UV-visible, Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), cyclic voltammetry (CV) and molecular modeling methods. FTIR and NMR results had justified that ARS was partly included into the β-CD cavity. The inclusion complex has 1:1 stoichiometry, where the apparent formation constant achieved was 4.137 × 103 L/mol using Benesi-Hildebrand equation. Cyclic voltammetry results shows the peak current decreased as the ARS molecule entered the hydrophobic cavity of β-CD. Molecular modeling results showed that the aromatic ring of the ARS entered into the secondary hydroxyl rim of the CD cavity was more thermodynamically favorable. The lowest stabilization energy, ΔE was -17.80 kcal/mol, and dipole-dipole interaction is was one of the driving forces for the inclusion complex formation.

  13. Cyp27c1 Red-Shifts the Spectral Sensitivity of Photoreceptors by Converting Vitamin A1 into A2.

    PubMed

    Enright, Jennifer M; Toomey, Matthew B; Sato, Shin-ya; Temple, Shelby E; Allen, James R; Fujiwara, Rina; Kramlinger, Valerie M; Nagy, Leslie D; Johnson, Kevin M; Xiao, Yi; How, Martin J; Johnson, Stephen L; Roberts, Nicholas W; Kefalov, Vladimir J; Guengerich, F Peter; Corbo, Joseph C

    2015-12-01

    Some vertebrate species have evolved means of extending their visual sensitivity beyond the range of human vision. One mechanism of enhancing sensitivity to long-wavelength light is to replace the 11-cis retinal chromophore in photopigments with 11-cis 3,4-didehydroretinal. Despite over a century of research on this topic, the enzymatic basis of this perceptual switch remains unknown. Here, we show that a cytochrome P450 family member, Cyp27c1, mediates this switch by converting vitamin A1 (the precursor of 11-cis retinal) into vitamin A2 (the precursor of 11-cis 3,4-didehydroretinal). Knockout of cyp27c1 in zebrafish abrogates production of vitamin A2, eliminating the animal's ability to red-shift its photoreceptor spectral sensitivity and reducing its ability to see and respond to near-infrared light. Thus, the expression of a single enzyme mediates dynamic spectral tuning of the entire visual system by controlling the balance of vitamin A1 and A2 in the eye. PMID:26549260

  14. Do Additional Bands (coastal, NIR-2, Red-Edge and Yellow) in WORLDVIEW-2 Multispectral Imagery Improve Discrimination of AN Invasive Tussock, Buffel Grass (cenchrus Ciliaris)?

    NASA Astrophysics Data System (ADS)

    Marshall, V.; Lewis, M.; Ostendorf, B.

    2012-07-01

    Our goals is to determine if Worldview-2 8-band multispectral imagery can be used to discriminate an invasive grass species namely, Buffel grass (Cenchrus ciliaris) in the subtropical arid parts of central Australia and whether it offers a tangible improvement on 4-band (visible and near infra red) multispectral imagery. A Worldview-2 scene was acquired for a 10*10km area just west of Alice Springs in central Australia following heavy rains of early Summer. Mixture Tuned Matched Filtering was used to classify the image. Target and background spectra were selected in the field and extracted from the image. Linear discriminate analysis (LDA) was used to examine the spectral separability of each group of the target/ background spectra. The importance of the additional spectral bands on the image classification was assessed by running LDA for both 8 and 4 bands (red, green, blue and NIR). LDA did not indicate improved separability between groups when additional spectral bands were applied. Preliminary classification results indicate that Buffel grass (Cenchrus ciliaris) is detected with an omission error 44%, commission error of 11.8% and overall accuracy of 59.5%. We were surprised that the additional spectral bands did not improve spectral separability and in part attribute this to the high degree of variance we observed within groups of spectra, which was particularly observable in the NIR2 and Yellow bands. The analyses may be significantly improved by acquiring imagery following the first big rains at the end of the dry season. At this time, phonological differences between our focal species and the surrounding native vegetation should be maximised. We suspect that Worldview-2 will offer even greater potential for the discrimination of Buffel grass under these conditions, being able to fully utilise the yellow-band in particular.

  15. The role of geological surfaces in determining visible-near infra red spectral signatures

    NASA Technical Reports Server (NTRS)

    Sommer, S. E.; Buckingham, W. F.

    1981-01-01

    The goal of the study described here is to determine new criteria for improved target discrimination in areas of hydrothermal mineralization. It is noted that the portion of materials, that is, geological surfaces detected by sensing devices, must be accurately determined before elemental and mineralogical characterization. The depth from which visible-near infrared radiation is reflected from target surfaces depends on composition and fabric. Reflectance spectra are obtained from binary mixtures of hematite, goethite, kaolinite and montmorillonite with a reflecting sphere spectrometer over a wavelength range of 400-2500 nm. The reflection (or absorption) intensity is plotted vs. the sample thickness (determined by scanning electron microscopy) to determine the sample thickness at which absorption saturates. The optical depth is seen to vary as a function of mineralogy and wavelength. In general, the maximum depth from which reflection features are discerned is from 12 to 47 microns measured in the visible-near infrared spectral region.

  16. Master-oscillator power-amplifier in the red spectral range for holographic displays

    NASA Astrophysics Data System (ADS)

    Blume, G.; Pohl, J.; Feise, D.; Wiedmann, J.; Ressel, P.; Eppich, B.; Sahm, A.; Ginolas, A.; Nedow, O.; Jendrzejewski, M.; Johne, P.; Hofmann, J.; Schiemangk, M.; Sumpf, B.; Erbert, G.; Paschke, K.

    2016-03-01

    RGB-light sources with a coherence length of several meters are required for holographic displays. Furthermore, these emitters must feature a high luminance and must be sufficiently small in size, to be employed in today's consumer market products. Therefore, an all-semiconductor based solution is preferred. We developed red-emitting semiconductor lasers at 635 nm and 647 nm with internal distributed Bragg reflectors and suitable amplifiers at these wavelengths to boost the lasers output power. We investigated tapered amplifiers containing a ridge-waveguide section as well as truncated tapered designs in master-oscillator power-amplifier configuration (MOPA). This allowed the generation of diffraction limited single mode emission by the MO-chip and subsequent amplification of the radiation by the PA-chip by more than 10 dB, without significantly degrading the coherence properties. We successfully demonstrated an optical output power of more than 300 mW at 635 nm and 500 mW at 647 nm. The radiation featured a linewidth below 10 MHz, which corresponds to a coherence length of at least several meters, well suited for a holographic system.

  17. Flow Injection Mass Spectral Fingerprints Demonstrate Chemical Differences in Rio Red Grapefruit with Respect to Year, Harvest Time, and Conventional versus Organic Farming

    PubMed Central

    Chen, Pei; Harnly, James M.; Lester, Gene E.

    2013-01-01

    Spectral fingerprints were acquired for Rio Red grapefruit using flow injection electrospray ionization with ion trap and time-of-flight mass spectrometry (FI-ESI-IT-MS and FI-ESI-TOF-MS). Rio Red grapefruits were harvested 3 times a year (early, mid, and late harvests) in 2005 and 2006 from conventionally and organically grown trees. Data analysis using analysis of variance principal component analysis (ANOVA-PCA) demonstrated that, for both MS systems, the chemical patterns were different as a function of farming mode (conventional vs organic), as well as growing year and time of harvest. This was visually obvious with PCA and was shown to be statistically significant using ANOVA. The spectral fingerprints provided a more inclusive view of the chemical composition of the grapefruit and extended previous conclusions regarding the chemical differences between conventionally and organically grown Rio Red grapefruit. PMID:20337420

  18. Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns

    SciTech Connect

    Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E.

    2013-05-06

    This work reports on the selective area growth by plasma-assisted molecular beam epitaxy and characterization of InGaN/GaN nanocolumnar heterostructures. The optimization of the In/Ga and total III/V ratios, as well as the growth temperature, provides control on the emission wavelength, either in the blue, green, or red spectral range. An adequate structure tailoring and monolithic integration in a single nanocolumnar heterostructure of three InGaN portions emitting in the red-green-blue colors lead to white light emission.

  19. The electronic absorption edge of petroleum

    SciTech Connect

    Mullins, O.C.; Mitra-Kirtley, S.; Zhu, Yifu

    1992-09-01

    The electronic absorption spectra of more than 20 crude oils and asphaltenes are examined. The spectral location of the electronic absorption edge varies over a wide range, from the near-infrared for heavy oils and asphaltenes to the near-UV for gas condensates. The functional form of the electronic absorption edge for all crude oils (measured) is characteristic of the {open_quotes}Urbach tail,{close_quotes} a phenomenology which describes electronic absorption edges in wide-ranging materials. The crude oils all show similar Urbach widths, which are significantly larger than those generally found for various materials but are similar to those previously reported for asphaltenes. Monotonically increasing absorption at higher photon energy continues for all crude oils until the spectral region is reached where single-ring aromatics dominate absorption. However, the rate of increasing absorption at higher energies moderates, thereby deviating from the Urbach behavior. Fluorescence emission spectra exhibit small red shifts from the excitation wavelength and small fluorescence peak widths in the Urbach regions of different crude oils, but show large red shifts and large peak widths in spectral regions which deviate from the Urbach behavior. This observation implies that the Urbach spectral region is dominated by lowest-energy electronic absorption of corresponding chromophores. Thus, the Urbach tail gives a direct measure of the population distribution of chromophores in crude oils. Implied population distributions are consistent with thermally activated growth of large chromophores from small ones. 12 refs., 8 figs.

  20. Fermi edge singularity and finite-frequency spectral features in a semi-infinite one-dimensional wire

    NASA Astrophysics Data System (ADS)

    Sheikhan, A.; Snyman, I.

    2012-08-01

    We theoretically study a charge qubit interacting with electrons in a semi-infinite one-dimensional wire. The system displays the physics of the Fermi edge singularity. Our results generalize known results for the Fermi edge system to the regime where excitations induced by the qubit can resolve the spatial structure of the scattering region. We find resonant features in the qubit tunneling rate as a function of the qubit level splitting. They occur at integer multiples of hvF/l. Here vF is the Fermi velocity of the electrons in the wire, and l is the distance from the tip of the wire to the point where it interacts with the qubit. These features are due to the constructive interference of the amplitudes for creating single coherent left- or right-moving charge fluctuation (plasmon) in the electron gas. As the coupling between the qubit and the wire is increased, the resonances are washed out. This is a clear signature of the increasingly violent Fermi sea shake-up, associated with the creation of many plasmons whose individual energies are too low to meet the resonance condition.

  1. Comparability of red/near-infrared reflectance and NDVI based on the spectral response function between MODIS and 30 other satellite sensors using rice canopy spectra.

    PubMed

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-01-01

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from -12.67% to 36.30% for the red reflectance, -8.52% to -0.23% for the NIR reflectance, and -9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7-17 showed

  2. Comparability of Red/Near-Infrared Reflectance and NDVI Based on the Spectral Response Function between MODIS and 30 Other Satellite Sensors Using Rice Canopy Spectra

    PubMed Central

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-01-01

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from −12.67% to 36.30% for the red reflectance, −8.52% to −0.23% for the NIR reflectance, and −9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7

  3. PHOTOMETRIC REDSHIFTS AND SYSTEMATIC VARIATIONS IN THE SPECTRAL ENERGY DISTRIBUTIONS OF LUMINOUS RED GALAXIES FROM SDSS DR7

    SciTech Connect

    Greisel, N.; Seitz, S.; Bender, R.; Saglia, R. P.; Snigula, J.; Drory, N.

    2013-05-10

    We describe the construction of a template set of spectral energy distributions (SEDs) for the estimation of photometric redshifts of luminous red galaxies (LRGs) with a Bayesian template fitting method. By examining the color properties of several publicly available SED sets within a redshift range of 0 < z {approx}< 0.5 and comparing them to Sloan Digital Sky Survey (SDSS) Data Release 7 data, we show that only some of the investigated SEDs approximately match the colors of the LRG data throughout the redshift range, however not at the quantitative level required for precise photometric redshifts. This is because the SEDs of galaxies evolve with time (and redshift) and because at fixed redshift the LRG colors have an intrinsic spread such that they cannot be matched by one SED only. We generate new SEDs by superposing model SEDs of composite stellar populations with a burst model, allowing both components to be reddened by dust, in order to match the data in five different redshift bins. We select a set of SEDs which represents the LRG data in color space within five redshift bins, thus defining our new SED template set for photometric redshift estimates. The results we obtain with the new template set and our Bayesian template fitting photometric redshift code (PhotoZ) are nearly unbiased, with a scatter of {sigma}{sub {Delta}z} = 0.027 (including outliers), a fraction of catastrophic outliers (|z{sub phot} - z{sub spec}|/(1 + z{sub spec}) > 0.15) of {eta} = 0.12%, and a normalized median absolute rest frame deviation (NMAD) of {sigma}{sub NMAD} = 1.48 Multiplication-Sign MAD = 0.017 for non-outliers. We show that templates that optimally describe the brightest galaxies (-24.5 {<=} M{sub R} {<=} -22.7) indeed vary from z = 0.1 to z = 0.5, consistent with aging of the stellar population. Furthermore, we find that templates that optimally describe galaxies at z < 0.1 strongly differ as a function of the absolute magnitude of the galaxies, indicating an increase in

  4. THE ASSEMBLY OF THE RED SEQUENCE AT z {approx} 1: THE COLOR AND SPECTRAL PROPERTIES OF GALAXIES IN THE Cl1604 SUPERCLUSTER

    SciTech Connect

    Lemaux, B. C.; Gal, R. R.; Lubin, L. M.; Fassnacht, C. D.; and others

    2012-02-01

    We investigate the properties of the 525 spectroscopically confirmed members of the Cl1604 supercluster at z {approx} 0.9 as part of the Observations of Redshift Evolution in Large Scale Environments survey. In particular, we focus on the photometric, stellar mass, morphological, and spectral properties of the 305 member galaxies of the eight clusters and groups that comprise the Cl1604 supercluster. Using an extensive Keck Low-Resolution Imaging Spectrometer (LRIS)/DEep Imaging Multi-Object Spectrograph (DEIMOS) spectroscopic database in conjunction with ten-band ground-based, Spitzer, and Hubble Space Telescope imaging, we investigate the buildup of the red sequence in groups and clusters at high redshift. Nearly all of the brightest and most massive red-sequence galaxies present in the supercluster environment are found to lie within the bounds of the cluster and group systems, with a surprisingly large number of such galaxies present in low-mass group systems. Despite the prevalence of these red-sequence galaxies, we find that the average cluster galaxy has a spectrum indicative of a star-forming galaxy, with a star formation rate between those of z {approx} 1 field galaxies and moderate-redshift cluster galaxies. The average group galaxy is even more active, exhibiting spectral properties indicative of a starburst. The presence of massive, red galaxies and the high fraction of starbursting galaxies present in the group environment suggest that significant processing is occurring in group environments at z {approx} 1 and earlier. There is a deficit of low-luminosity red-sequence galaxies in all Cl1604 clusters and groups, suggesting that such galaxies transition to the red sequence at later times. Extremely massive ({approx}10{sup 12} M{sub sun}) red-sequence galaxies routinely observed in rich clusters at z {approx} 0 are also absent from the Cl1604 clusters and groups. We suggest that such galaxies form at later times through merging processes. There are

  5. Evaluation of spectral light management on growth of container-grown willow oak, nuttall oak and summer red maple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant response to blue, red, gray or black shade cloth was evaluated with willow oak (Quercus phellos L.), Nuttall oak (Quercus nuttallii Palmer, Nuttall) and Summer Red maple (Acer rubrum L. ‘Summer Red’) liners. Light transmitted through the colored shade cloth had no influence on germination of ...

  6. A Substantial Population of Red Galaxies at z > 2: Modeling of the Spectral Energy Distributions of an Extended Sample

    NASA Astrophysics Data System (ADS)

    Förster Schreiber, N. M.; van Dokkum, P. G.; Franx, M.; Labbé, I.; Rudnick, G.; Daddi, E.; Illingworth, G. D.; Kriek, M.; Moorwood, A. F. M.; Rix, H.-W.; Röttgering, H.; Trujillo, I.; van der Werf, P.; van Starkenburg, L.; Wuyts, S.

    2004-11-01

    We investigate the nature of the substantial population of high-redshift galaxies with Js-Ks>=2.3 colors recently discovered as part of our Faint Infrared Extragalactic Survey (FIRES). This color cut efficiently isolates galaxies at z>2 with red rest-frame optical colors (``distant red galaxies'' [DRGs]). We select Js-Ks>=2.3 objects in both FIRES fields, the ~2.5m×2.5m Hubble Deep Field-South (HDF-S) and the ~5'×5' field around the MS 1054-03 cluster at z=0.83; the surface densities at Ks,Vega<21 mag are 1.6+/-0.6 and 1.0+/-0.2 arcmin-2, respectively. We here discuss a subsample of 34 DRGs at 2<=z<=3.5: 11 at Ks,Vega<22.5 mag in HDF-S and 23 at Ks,Vega<21.7 mag in the MS 1054-03 field. This sample enables for the first time a robust assessment of the population properties of DRGs. We analyze the λ=0.3-2.2 μm spectral energy distributions (SEDs) constructed from our very deep near-infrared (NIR) and optical imaging collected at the ESO Very Large Telescope and from the Hubble Space Telescope. We develop diagnostics involving the I814-Js, Js-H, and H-Ks colors to argue that the red NIR colors of our DRG sample cannot be attributed solely to interstellar dust extinction and require for many the presence of an evolved stellar population with a prominent Balmer/4000 Å break. In the rest frame, the optical colors of DRGs fall within the envelope of normal nearby galaxies and the ultraviolet colors suggest a wide range in star formation activity and/or extinction. This is in stark contrast with the much bluer and more uniform SEDs of Lyman break galaxies (LBGs). From evolutionary synthesis modeling assuming constant star formation (CSF), we derive for the DRGs old ages, large extinctions, and high stellar masses, mass-to-light ratios, and star formation rates (SFRs). For solar metallicity, a Salpeter initial mass function (IMF) between 0.1 and 100 Msolar, and the Calzetti et al. extinction law, the median values for the HDF-S (MS 1054-03 field) sample are 1.7 (2

  7. Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. II. Spectral line formation in the atmosphere of a giant located near the RGB tip

    NASA Astrophysics Data System (ADS)

    Kučinskas, A.; Steffen, M.; Ludwig, H.-G.; Dobrovolskas, V.; Ivanauskas, A.; Klevas, J.; Prakapavičius, D.; Caffau, E.; Bonifacio, P.

    2013-01-01

    Aims: We investigate the role of convection in the formation of atomic and molecular lines in the atmosphere of a red giant star. For this purpose we study the formation properties of spectral lines that belong to a number of astrophysically important tracer elements, including neutral and singly ionized atoms (Li I, N I, O I, Na I, Mg I, Al I, Si I, Si II, S I, K I, Ca I, Ca II, Ti I, Ti II, Cr I, Cr II, Mn I, Fe I, Fe II, Co I, Ni I, Zn I, Sr II, Ba II, and Eu II), and molecules (CH, CO, C2, NH, CN, and OH). Methods: We focus our investigation on a prototypical red giant located close to the red giant branch (RGB) tip (Teff = 3660 K, log g = 1.0, [M/H] = 0.0). We used two types of model atmospheres, 3D hydrodynamical and classical 1D, calculated with the CO5BOLD and LHD stellar atmosphere codes, respectively. Both codes share the same atmospheric parameters, chemical composition, equation of state, and opacities, which allowed us to make a strictly differential comparison between the line formation properties predicted in 3D and 1D. The influence of convection on the spectral line formation was assessed with the aid of 3D-1D abundance corrections, which measure the difference between the abundances of chemical species derived with the 3D hydrodynamical and 1D classical model atmospheres. Results: We find that convection plays a significant role in the spectral line formation in this particular red giant. The derived 3D-1D abundance corrections rarely exceed ± 0.1 dex when lines of neutral atoms and molecules are considered, which is in line with the previous findings for solar-metallicity red giants located on the lower RGB. The situation is different with lines that belong to ionized atoms, or to neutral atoms with high ionization potential. In both cases, the corrections for high-excitation lines (χ > 8 eV) may amount to Δ3D-1D ~ -0.4 dex. The 3D-1D abundance corrections generally show a significant wavelength dependence; in most cases they are smaller in

  8. Fourier-spectral element approximation of the ion-electron Braginskii system with application to tokamak edge plasma in divertor configuration

    NASA Astrophysics Data System (ADS)

    Minjeaud, Sebastian; Pasquetti, Richard

    2016-09-01

    Due to the extreme conditions required to produce energy by nuclear fusion in tokamaks, simulating the plasma behavior is an important but challenging task. We focus on the edge part of the plasma, where fluid approaches are probably the best suited, and our approach relies on the Braginskii ion-electron model. Assuming that the electric field is electrostatic, this yields a set of 10 strongly coupled and non-linear conservation equations that exhibit multiscale and anisotropy features. The computational domain is a torus of complex geometrical section, that corresponds to the divertor configuration, i.e. with an "X-point" in the magnetic surfaces. To capture the complex physics that is involved, high order methods are used: The time-discretization is based on a Strang splitting, that combines implicit and explicit high order Runge-Kutta schemes, and the space discretization makes use of the spectral element method in the poloidal plane together with Fourier expansions in the toroidal direction. The paper thoroughly describes the algorithms that have been developed, provides some numerical validations of the key algorithms and exhibits the results of preliminary numerical experiments. In particular, we point out that the highest frequency of the system is intermediate between the ion and electron cyclotron frequencies.

  9. Spectral characterization of forest damage occurring on Whiteface Mountain, NY - Studies with the Fluorescence Line Imager (FLI) and ground-based spectrometers

    NASA Technical Reports Server (NTRS)

    Rock, B. N.; Moss, D. M.; Miller, J. R.; Freemantle, J. R.; Boyer, M. G.

    1990-01-01

    Ground-based spectral characteristics of fir wave damage and an analysis of calibrated FLI data acquired along the same fir wave utilized for the in situ measurements are presented. Derivative curve data were produced from both in situ and FLI reflectance measurements for the red edge spectral region for birch and for various portions of a fir wave. The results suggested that with proper atmospheric correction of airborne imaging spectrometer data sets, the derivative curve approach will provide an accurate means of assessing red edge parameters, and that such data will permit identification of specific types of forest damage on the basis of spectral fine features.

  10. Curie point depth beneath the Barramiya-Red Sea coast area estimated from spectral analysis of aeromagnetic data

    NASA Astrophysics Data System (ADS)

    Abd El Nabi, Sami Hamed

    2012-01-01

    The geothermal regime beneath the Barramiya-Red Sea coast area of the Central Eastern Desert of Egypt has been determined by using the Curie point depth, which is temperature dependent. This study is based on the analysis of aeromagnetic data. The depth to the tops and centroid of the magnetic anomalies are calculated by power spectrum method for the whole area. The result of this investigation indicates, two new maps of the Curie point depth (CPD) and the surface heat flow ( q) maps of the study area. The coastal regions are characterized by high heat flow (83.6 mW/m 2), due to the geothermic nature of the region, and shallow Curie depth (22.5 km), where (CPD) depends on the tectonic regime and morphology in the eastern part of the area. The western portion of the studied area has a lower heat flow (<50 mW/m 2) and deeper Curie depth (˜40 km), due to the existence of a large areal extent of negative Bouguer anomaly in the NE-SW direction. In addition to its bordering to the Red Sea margin, such high heat flow anomaly is associated with the increased earthquake swarms activity in the Abu Dabbab area.

  11. Influence of oxygen saturation on the optical scattering properties of human red blood cells in the spectral range 250 to 2,000 nm.

    PubMed

    Friebel, Moritz; Helfmann, Jürgen; Netz, Uwe; Meinke, Martina

    2009-01-01

    The intrinsic optical parameters absorption coefficient mu(a), scattering coefficient micros, anisotropy factor g, and effective scattering coefficient micros were determined for human red blood cell (RBC) suspensions of hematocrit 33.2% dependent on the oxygen saturation (SAT O(2)) in the wavelength range 250 to 2,000 nm, including the range above 1,100 nm, about which there are no data available in the literature. Integrating sphere measurements of light transmittance and reflectance in combination with inverse Monte Carlo simulation were carried out for SAT O(2) levels of 100 and 0%. In the wavelength range up to 1,200 nm, the absorption behavior is determined by the hemoglobin absorption. The spectral range above the cells' absorption shows no dependence on SAT O(2) and approximates the absorption of water with values 20 to 30% below the respective values for water. Parameters micros and g are significantly influenced by the SAT O(2)-induced absorption changes. Above 600 nm, micros decreases continuously from values of 85 mm(-1) to values of 30 mm(-1) at 2,000 nm. The anisotropy factor shows a slight decrease with wavelengths above 600 nm. In the spectral regions of 1,450 and 1,900 nm where water has local absorption maxima, g shows a significant decrease down to 0.85, whereas micros increases. PMID:19566295

  12. Spectral downshifting from blue to near infer red region in Ce3+-Nd3+ co-doped YAG phosphor

    NASA Astrophysics Data System (ADS)

    Sawala, N. S.; Omanwar, S. K.

    2016-07-01

    The YAG phosphors co-doped with Ce3+-Nd3+ ions by varying concentration of Nd3+ ion from 1 mol% to 15 mol% were successfully synthesized by conventional solid state reaction method. The phosphors were characterized by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied in near infra red (NIR) and ultra violet visible (UV-VIS) region. The synthesized phosphors can convert a blue region photon (453 nm) into photons of NIR region (1063 nm). The energy transfer (ET) process was studied by time decay curve and PL spectra. The theoretical value of energy transfer efficiency (ETE) was calculated from time decay luminescence measurement and the maximum efficiency approached up to 82.23%. Hence this phosphor could be prime candidate as a downshifting (DS) luminescent convertor (phosphor) in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss in the solar cells.

  13. Infra-red spectral microscopy of standing-wave resonances in single metal-dielectric-metal thin-film cavity

    NASA Astrophysics Data System (ADS)

    Nath, Janardan; Panjwani, Deep; Khalilzadeh-Rezaie, Farnood; Yesiltas, Mehmet; Smith, Evan M.; Ginn, James C.; Shelton, David J.; Hirschmugl, Carol; Cleary, Justin W.; Peale, Robert E.

    2015-09-01

    Resonantly absorbing thin films comprising periodically sub-wavelength structured metal surface, dielectric spacer, and metal ground plane are a topic of current interest with important applications. These structures are frequently described as "metamaterials", where effective permittivity and permeability with dispersion near electric and magnetic resonances allow impedance matching to free space for maximum absorption. In this paper, we compare synchrotron-based infrared spectral microscopy of a single isolated unit cell and a periodic array, and we show that the resonances have little to do with periodicity. Instead, the observed absorption spectra of usual periodically structured thin films are best described as due to standing-wave resonances within each independent unit cell, rather than as due to effective optical constants of a metamaterial. The effect of having arrays of unit cells is mainly to strengthen the absorption by increasing the fill factor, and such arrays need not be periodic. Initial work toward applying the subject absorbers to room-temperature bolometer arrays is presented.

  14. The characteristic analysis of spectral image for cabbage leaves damaged by diamondback moth pests

    NASA Astrophysics Data System (ADS)

    Lin, Li-bo; Li, Hong-ning; Cao, Peng-fei; Qin, Feng; Yang, Shu-ming; Feng, Jie

    2015-02-01

    Cabbage growth and health diagnosis are important parts for cabbage fine planting, spectral imaging technology with the advantages of obtaining spectrum and space information of the target at the same time, which has become a research hotspot at home and abroad. The experiment measures the reflection spectrum at different stages using liquid crystal tunable filter (LCTF) and monochromatic CMOS camera composed of spectral imaging system for cabbage leaves damaged by diamondback moth pests, and analyzes its feature bands and the change of spectral parameters. The study shows that the feature bands of cabbage leaves damaged by diamondback moth pests have a tendency to blue light direction, the red edge towards blue shift, and red valley raising in spectral characteristic parameters, which have a good indication in diagnosing the extent of cabbage damaged by pests. Therefore, it has a unique advantage of monitoring the cabbage leaves damaged by diamondback moth pests by combinating feature bands and spectral characteristic parameters in spectral imaging technology.

  15. Bimodal activation of different neuron classes with the spectrally red-shifted channelrhodopsin chimera C1V1 in Caenorhabditis elegans.

    PubMed

    Erbguth, Karen; Prigge, Matthias; Schneider, Franziska; Hegemann, Peter; Gottschalk, Alexander

    2012-01-01

    The C. elegans nervous system is particularly well suited for optogenetic analyses of circuit function: Essentially all connections have been mapped, and light can be directed at the neuron of interest in the freely moving, transparent animals, while behavior is observed. Thus, different nodes of a neuronal network can be probed for their role in controlling a particular behavior, using different optogenetic tools for photo-activation or -inhibition, which respond to different colors of light. As neurons may act in concert or in opposing ways to affect a behavior, one would further like to excite these neurons concomitantly, yet independent of each other. In addition to the blue-light activated Channelrhodopsin-2 (ChR2), spectrally red-shifted ChR variants have been explored recently. Here, we establish the green-light activated ChR chimera C1V1 (from Chlamydomonas and Volvox ChR1's) for use in C. elegans. We surveyed a number of red-shifted ChRs, and found that C1V1-ET/ET (E122T; E162T) works most reliable in C. elegans, with 540-580 nm excitation, which leaves ChR2 silent. However, as C1V1-ET/ET is very light sensitive, it still becomes activated when ChR2 is stimulated, even at 400 nm. Thus, we generated a highly efficient blue ChR2, the H134R; T159C double mutant (ChR2-HR/TC). Both proteins can be used in the same animal, in different neurons, to independently control each cell type with light, enabling a further level of complexity in circuit analyses. PMID:23056472

  16. High spectral resolution imaging of the dynamical atmosphere of the red supergiant Antares in the CO first overtone lines with VLTI/AMBER

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.; Hofmann, K.-H.; Schertl, D.; Weigelt, G.; Baffa, C.; Chelli, A.; Petrov, R.; Robbe-Dubois, S.

    2013-07-01

    Aims: We present aperture-synthesis imaging of the red supergiant Antares (α Sco) in the CO first overtone lines. Our goal is to probe the structure and dynamics of the outer atmosphere. Methods: Antares was observed between 2.28 μm and 2.31 μm with VLTI/AMBER with spectral resolutions of up to 12 000 and angular resolutions as high as 7.2 mas at two epochs with a time interval of one year. Results: The reconstructed images in individual CO lines reveal that the star appears differently in the blue wing, line center, and red wing. In 2009, the images in the line center and red wing show an asymmetrically extended component, while the image in the blue wing shows little trace of it. In 2010, however, the extended component appears in the line center and blue wing, and the image in the red wing shows only a weak signature of the extended component. Our modeling of these AMBER data suggests that there is an outer atmosphere (MOLsphere) extending to 1.2-1.4 R⋆ with CO column densities of (0.5-1) × 1020 cm-2 and a temperature of ~2000 K. The CO line images observed in 2009 can be explained by a model in which a large patch or clump of CO gas is infalling at only 0-5 km s-1, while the CO gas in the remaining region is moving outward much faster at 20-30 km s-1. The images observed in 2010 suggest that a large clump of CO gas is moving outward at 0-5 km s-1, while the CO gas in the remaining region is infalling much faster at 20-30 km s-1. In contrast to the images in the CO lines, the AMBER data in the continuum show only a slight deviation from limb-darkened disks and only marginal time variations. We derive a limb-darkened disk diameter of 37.38 ± 0.06 mas and a power-law-type limb-darkening parameter of (8.7 ± 1.6) × 10-2 (2009) and 37.31 ± 0.09 mas and (1.5 ± 0.2) × 10-1 (2010). We also obtain an effective temperature of 3660 ± 120 K (the error includes the effects of the temporal flux variation that is assumed to be the same as Betelgeuse) and a

  17. [The changes in spectral features of the staple-food bamboos of giant panda after flowering].

    PubMed

    Liu, Xue-Hua; Wu, Yan

    2012-12-01

    Large-area flowering of the giant pandas' staple food is an important factor which can influence their survival. Therefore, it is necessary to predict the bamboo flowering. Foping Nature Reserve was taken as the study area. The research selected the giant pandas' staple-food bamboos Bashania fargesii, Fargesia qinlingensis and Fargesia dracocephala with different flowering situations (i. e., flowering, potential flowering, non-flowering with far distance) to measure the spectral reflectance of bamboo leaves. We studied the influence of bamboo flowering on the spectral features of three bamboo species through analyzing the original spectral reflectance and their red edge parameters. The results showed that (1) the flowering changed the spectra features of bamboo species. The spectral reflectance of B. fargesii shows a pattern: flowering bamboo < potential flowering bamboo < non-flowering bamboo with far distance, while F. qinlingensis and F. dracocephala show the different pattern: flowering bamboo > or = potential flowering bamboo > non-flowering bamboo with far distance. Among three bamboo species, F. dracocephala showed the greatest change, and then F. qinlingensis. (2) After bamboo flowering, the red edge of B. fargesii has no obvious shifting, while the other two bamboos have distinctive shifting towards the shorter waves. The study found that the original spectral feature and the red edge all changed under various flowering states, which can be used to provide the experimental basis and theoretic support for the future prediction of bamboo flowering through remote sensing. PMID:23427564

  18. [Research on the spectral characteristics of grassland in arid regions based on hyperspectral image].

    PubMed

    Zhang, Chun-mei; Zhang, Jian-ming

    2012-02-01

    The grassland spectrum was got from Hyperion images of Shiyang River Basin using PPI, after FLAASH atmosphere correction, to understand the spectral characteristics quantitatively. The results show that red edge moves left, slope reduced, blue and yellow edge feature is abated, reflectance is higher in visible bands, and lower near-infrared bands when grassland is at decline stage relative to the spectrum characteristics of grassland at well growth. The red edge, green peaks, absorption valley location of blue and red light keep consistent for different coverage grassland, and spectrum absorption characteristics (band depth, width, area, symmetry) in visual bands change regularly as coverage increases, so it can be a basis for extraction or judgment of vegetation coverage. PMID:22512187

  19. Use of a Remote Sensing Method to Estimate the Influence of Anthropogenic Factors on the Spectral Reflectance of Plant Species

    NASA Astrophysics Data System (ADS)

    Krezhova, Dora D.; Yanev, Tony K.

    2007-04-01

    Results from a remote sensing study of the influence of stress factors on the leaf spectral reflectance of wheat and tomato plants contaminated by viruses and pea plants treated with herbicides are presented and discussed. The changes arising in the spectral reflectance characteristics of control and treated plants are estimated through statistical methods as well as through derivative analysis to determine specific reflectance features in the red edge region.

  20. [Spectral features analysis of Pinus massoniana with pest of Dendrolimus punctatus Walker and levels detection].

    PubMed

    Xu, Zhang-Hua; Liu, Jian; Yu, Kun-Yong; Gong, Cong-Hong; Xie, Wan-Jun; Tang, Meng-Ya; Lai, Ri-Wen; Li, Zeng-Lu

    2013-02-01

    Taking 51 field measured hyperspectral data with different pest levels in Yanping, Fujian Province as objects, the spectral reflectance and first derivative features of 4 levels of healthy, mild, moderate and severe insect pest were analyzed. On the basis of 7 detecting parameters construction, the pest level detecting models were built. The results showed that (1) the spectral reflectance of Pinus massoniana with pests were significantly lower than that of healthy state, and the higher the pest level, the lower the reflectance; (2) with the increase in pest level, the spectral reflectance curves' "green peak" and "red valley" of Pinus massoniana gradually disappeared, and the red edge was leveleds (3) the pest led to spectral "green peak" red shift, red edge position blue shift, but the changes in "red valley" and near-infrared position were complicated; (4) CARI, RES, REA and REDVI were highly relevant to pest levels, and the correlations between REP, RERVI, RENDVI and pest level were weak; (5) the multiple linear regression model with the variables of the 7 detection parameters could effectively detect the pest levels of Dendrolimus punctatus Walker, with both the estimation rate and accuracy above 0.85. PMID:23697126

  1. Identification of Cyanobacteriochromes Detecting Far-Red Light.

    PubMed

    Rockwell, Nathan C; Martin, Shelley S; Lagarias, J Clark

    2016-07-19

    The opacity of mammalian tissue to visible light and the strong attenuation of infrared light by water at ≥900 nm have contributed to growing interest in the development of far-red and near-infrared absorbing tools for visualizing and actuating responses within live cells. Here we report the discovery of cyanobacteriochromes (CBCRs) responsive to light in this far-red window. CBCRs are linear tetrapyrrole (bilin)-based light sensors distantly related to plant phytochrome sensors. Our studies reveal far-red (λmax = 725-755 nm)/orange (λmax = 590-600 nm) and far-red/red (λmax = 615-685 nm) photoswitches that are small (<200 amino acids) and can be genetically reconstituted in living cells. Phylogenetic analysis and characterization of additional CBCRs demonstrated that far-red/orange CBCRs evolved after a complex transition from green/red CBCRs known for regulating complementary chromatic acclimation. Incorporation of different bilin chromophores demonstrated that tuning mechanisms responsible for red-shifted chromophore absorption act at the A-, B-, and/or C-rings, whereas photoisomerization occurs at the D-ring. Two such proteins exhibited detectable fluorescence extending well into the near-infrared region. This work extends the spectral window of CBCRs to the edge of the infrared, raising the possibility of using CBCRs in synthetic biology applications in the far-red region of the spectrum. PMID:27295035

  2. Adapting photosynthesis to the near-infrared: non-covalent binding of phycocyanobilin provides an extreme spectral red-shift to phycobilisome core-membrane linker from Synechococcus sp. PCC7335.

    PubMed

    Miao, Dan; Ding, Wen-Long; Zhao, Bao-Qing; Lu, Lu; Xu, Qian-Zhao; Scheer, Hugo; Zhao, Kai-Hong

    2016-06-01

    Phycobiliproteins that bind bilins are organized as light-harvesting complexes, phycobilisomes, in cyanobacteria and red algae. The harvested light energy is funneled to reaction centers via two energy traps, allophycocyanin B and the core-membrane linker, ApcE1 (conventional ApcE). The covalently bound phycocyanobilin (PCB) of ApcE1 absorbs near 660 nm and fluoresces near 675 nm. In cyanobacteria capable of near infrared photoacclimation, such as Synechococcus sp. PCC7335, there exist even further spectrally red shifted components absorbing >700 nm and fluorescing >710 nm. We expressed the chromophore domain of the extra core-membrane linker from Synechococcus sp. PCC7335, ApcE2, in E. coli together with enzymes generating the chromophore, PCB. The resulting chromoproteins, PCB-ApcE2(1-273) and the more truncated PCB-ApcE2(24-245), absorb at 700 nm and fluoresce at 714 nm. The red shift of ~40 nm compared with canonical ApcE1 results from non-covalent binding of the chromophore by which its full conjugation length including the Δ3,3(1) double bond is preserved. The extreme spectral red-shift could not be ascribed to exciton coupling: dimeric PCB-ApcE2(1-273) and monomeric-ApcE2(24-245) absorbed and fluoresced similarly. Chromophorylation of ApcE2 with phycoerythrobilin- or phytochromobilin resulted in similar red shifts (absorption at 615 and 711 nm, fluorescence at 628 or 726 nm, respectively), compared to the covalently bound chromophores. The self-assembled non-covalent chromophorylation demonstrates a novel access to red and near-infrared emitting fluorophores. Brightly fluorescent biomarking was exemplified in E. coli by single-plasmid transformation. PMID:27045046

  3. Spectral Signatures of Photosynthesis. I. Review of Earth Organisms

    NASA Astrophysics Data System (ADS)

    Kiang, Nancy Y.; Siefert, Janet; Govindjee; Blankenship, Robert E.

    2007-02-01

    Why do plants reflect in the green and have a ``red edge '' in the red, and should extrasolar photosynthesis be the same? We provide (1) a brief review of how photosynthesis works, (2) an overview of the diversity of photosynthetic organisms, their light harvesting systems, and environmental ranges, (3) a synthesis of photosynthetic surface spectral signatures, and (4) evolutionary rationales for photosynthetic surface reflectance spectra with regard to utilization of photon energy and the planetary light environment. We found the `` near-infrared (NIR) end '' of the red edge to trend from blue-shifted to reddest for (in order) snow algae, temperate algae, lichens, mosses, aquatic plants, and finally terrestrial vascular plants. The red edge is weak or sloping in lichens. Purple bacteria exhibit possibly a sloping edge in the NIR. More studies are needed on pigment-protein complexes, membrane composition, and measurements of bacteria before firm conclusions can be drawn about the role of the NIR reflectance. Pigment absorbance features are strongly correlated with features of atmospheric spectral transmittance: P680 in Photosystem II with the peak surface incident photon flux density at ~685 nm, just before an oxygen band at 687.5 nm; the NIR end of the red edge with water absorbance bands and the oxygen A-band at 761 nm; and bacteriochlorophyll reaction center wavelengths with local maxima in atmospheric and water transmittance spectra. Given the surface incident photon flux density spectrum and resonance transfer in light harvesting, we propose some rules with regard to where photosynthetic pigments will peak in absorbance: (1) the wavelength of peak incident photon flux; (2) the longest available wavelength for core antenna or reaction center pigments; and (3) the shortest wavelengths within an atmospheric window for accessory pigments. That plants absorb less green light may not be an inefficient legacy of evolutionary history, but may actually satisfy the

  4. Characterization of red-near infrared transition for wheat and chickpea using 3 nm bandwidth data

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Vijayan, D.; Prasad, T. S.

    2001-01-01

    Enhancement of space based capabilities to discriminate different crops and different varieties of a particular crop needs measurement of (i) the shift in red edge and (ii) the slope of the sudden rise of reflectance in 680 - 760 nm spectral region as a function of Days After Sowing (DAS). To develop the knowledge base for catering to the analysis of future space-based hyperspectral measurements, ground based measurements in 3 nm bandwidth in visible - near Infrared region together with corresponding Leaf Area Index (LAI) observations were taken over the Crop Growth Cycle (CGC) of Wheat and Chickpea. The red edge for wheat crop was at 679 nm for 25 DAS and reached the upper limit i.e., 693.7 nm at 84 DAS and thereafter shifted backward to 679 nm at 108 DAS. There was no change in red edge value of 684.9 nm during 40 to 49 DAS and of 687.8 nm during 55 to 71 DAS. The slope of Red to NIR transition for wheat varied from 0.457 to peak value of 0.784 during 25 to 71 DAS and thereafter decreased to 0.073 at 108 DAS. The peak of Red to Near Infrared (NIR) transition slope and Ratio Vegetation Index (RVI) occurred at the same time i.e., 71 DAS. However, the upper most value of red edge shift occurred at 84 DAS. Paper discusses the above aspects including role of mid point of Red to NIR transition, interrelationships among the Red-NIR transition Slope, Red Edge, LAI and RVI for wheat and chickpea.

  5. Close-packed Arrays of Transition-edge X-ray Microcalorimeters with High Spectral Resolution at 5.9 keV

    NASA Technical Reports Server (NTRS)

    Iyomoto, N.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Figueroa-Feliciano, E.

    2007-01-01

    We present measurements of high fill-factor arrays of superconducting transition-edge x-ray microcalorimeters designed to provide rapid thermalization of the x-ray energy. We designed an x-ray absorber that is cantilevered over the sensitive part of the thermometer itself, making contact only at normal metal-features. With absorbers made of electroplated gold, we have demonstrated an energy resolution between 2.4 and 3.1 eV at 5.9 keV on 13 separate pixels. We have determined the thermal and electrical parameters of the devices throughout the superconducting transition, and, using these parameters, have modeled all aspects of the detector performance.

  6. Close-packed arrays of transition-edge x-ray microcalorimeters with high spectral resolution at 5.9 keV

    SciTech Connect

    Iyomoto, N.; Bandler, S. R.; Brekosky, R. P.; Brown, A.-D.; Chervenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Figueroa-Feliciano, E.

    2008-01-07

    We present measurements of high fill-factor arrays of superconducting transition-edge x-ray microcalorimeters designed to provide rapid thermalization of the x-ray energy. We designed an x-ray absorber that is cantilevered over the sensitive part of the thermometer itself, making contact only at normal-metal features. With absorbers made of electroplated gold, we have demonstrated an energy resolution between 2.4 and 3.1 eV at 5.9 keV on 13 separate pixels. We have determined the thermal and electrical parameters of the devices throughout the superconducting transition and, using these parameters, have modeled all aspects of the detector performance.

  7. [Plant Spectral Discrimination Based on Phenological Features].

    PubMed

    Zhang, Lei; Zhao, Jian-long; Jia, Kun; Li, Xiao-song

    2015-10-01

    Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation

  8. The Cenozoic rotational extrusion of the Chuan Dian Fragment: New paleomagnetic results from Paleogene red-beds on the southeastern edge of the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Tong, Ya-Bo; Yang, Zhenyu; Wang, Heng; Gao, Liang; An, Chun-Zhi; Zhang, Xu-Dong; Xu, Ying-Chao

    2015-09-01

    Paleomagnetic studies were conducted on the Eocene and Oligocene strata at the western part of the Chuan Dian Fragment in order to describe the crustal deformation induced by continuous penetration of the Indian plate into Eurasia during the late Cenozoic. High-temperature magnetic components with unblocking temperatures of ~ 680 °C were isolated, and positive fold and/or reversal tests reveal the primary nature of the magnetization. The tilt-corrected site-mean directions obtained from the Oligocene and middle-early Eocene strata are, respectively, Ds = 200.9°, Is = - 31.3°, k = 52.8, α95 = 7.7° and Ds = 29.7°, Is = 32.0°, k = 44.9, α95 = 5.6°. Comparison of these results with previous paleomagnetic data from the Chuan Dian Fragment shows that the western and central parts of the Chuan Dian Fragment experienced ~ 20° integral clockwise rotation relative to East Asia since the middle Miocene. However, the eastern part of the Chuan Dian Fragment has experienced different rotational deformation relative to East Asia since the Pliocene, because of the intense regional crustal deformation and activity on fault systems. The eastern boundary of the Chuan Dian Fragment was bounded by the Yuanmou-Luezhijiang left lateral strike-slip fault prior to the Pliocene, and then substituted by the Xiaojiang left lateral strike-slip fault since the Pliocene, due to the eastwards spreading of the clockwise rotational movement of the Chuan Dian Fragment. The evolutionary characteristics of the Ailaoshan-Red River and Xianshuihe-Xiaojiang strike-slip faults were controlled by the difference between the clockwise rotational extrusion velocities of the Chuan Dian Fragment and the Indochina Block.

  9. Spectral optimization of the color temperature tunable white light-emitting diode (LED) cluster consisting of direct-emission blue and red LEDs and a diphosphor conversion LED.

    PubMed

    Zhong, Ping; He, Guoxing; Zhang, Minhao

    2012-09-10

    The correlated color temperature (CCT) tunable white-light LED cluster, which consists of direct-emission blue and red LEDs as well as phosphor-conversion (PC) LEDs packaged by combining green and orange phosphors with a blue LED die, has been obtained by nonlinear program for maximizing luminous efficacy (LE) of radiation (LER) under conditions of both color rendering index (CRI) and special CRI of R9 for strong red above 90 at CCTs of 2700 K to 6500 K. The optimal peak wavelengths of blue LED, red LED, blue LED die, green and orange phosphors are 465 nm, 628 nm, 452 nm, 530 nm and 586 nm, respectively. The real CCT tunable PC/red/blue LED cluster with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W has been realized at CCTs of 2722 K to 6464 K. The deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance. PMID:23037535

  10. Effect of phosphorus deficiency on spectral reflectance and morphology of soybean plants

    USGS Publications Warehouse

    Milton, N.M.; Eiswerth, B.A.; Ager, C.M.

    1991-01-01

    Soybean plants were grown in hydroponic solutions having three concentration levels of phosphorus. Spectral reflectance changes included higher reflectance in the green and yellow portions of the electromagnetic spectrum in phosphorus-deficient plants and a difference in position of the long wavelength edge (the red edge) of the chlorophyll absorption band centered near 0.68 ??m. Plants having the least phosphorus in the growing medium did not show the normal shift of the red edge to longer wavelength which occurs as leaves mature. Shoot and root biomass were significantly lower in the phosphorus-deficient plants. These results are consistent with those obtained when soybean plants are dosed with elevated concentrations of metallic elements. We hypothesize that nutrient imbalances or anomalous metal concentrations in the soil set up physiological conditions at the soil/root interface that are responsible for the reflectance differences observed in laboratory and field studies of plants growing in substrates enriched in metallic elements. ?? 1991.

  11. Arsenic- and selenium-induced changes in spectral reflectance and morphology of soybean plants

    USGS Publications Warehouse

    Milton, N.M.; Ager, C.M.; Eiswerth, B.A.; Power, M.S.

    1989-01-01

    Soybean (Glycine max) plants were grown in hydroponic solutions treated with high concentrations of either arsenic or selenium. Spectral reflectance changes in arsenic-dosed plants included a shift to shorter wavelengths in the long-wavelength edge of the chlorophyll absorption band centered at 680 nm (the red edge) and higher reflectance in the 550-650 nm region. These results are consistent with vegetation reflectance anomalies observed in previous greenhouse experiments and in airborne radiometer studies. The selenium-dosed plants contrast, exhibited a shift to longer wavelengths of the red edge and lower reflectance between 550 nm and 650 wh when compared with control plants. Morphological effects of arsenic uptake included lower overall biomass, stunted and discolored roots, and smaller leaves oriented more vertically than leaves of control plants. Selenium-dosed plants also displayed morphological changes, but root and leaf biomass were less affected than were those of arsenic-dosed plants when compared to control plants. ?? 1989.

  12. Zwitterionic [4]helicene: a water-soluble and reversible pH-triggered ECD/CPL chiroptical switch in the UV and red spectral regions.

    PubMed

    Pascal, Simon; Besnard, Céline; Zinna, Francesco; Di Bari, Lorenzo; Le Guennic, Boris; Jacquemin, Denis; Lacour, Jérôme

    2016-05-18

    The chiroptical switching properties of a readily accessible and water-soluble diaza [4]helicene are disclosed. This zwitterionic dye displays pH-dependent absorption and emission properties and this enables a reversible turn on/off of electronic circular dichroism at 300 nm and of circularly polarized luminescence in the red region upon protonation/deprotonation. PMID:27139039

  13. Edge Bioinformatics

    Energy Science and Technology Software Center (ESTSC)

    2015-08-03

    Edge Bioinformatics is a developmental bioinformatics and data management platform which seeks to supply laboratories with bioinformatics pipelines for analyzing data associated with common samples case goals. Edge Bioinformatics enables sequencing as a solution and forward-deployed situations where human-resources, space, bandwidth, and time are limited. The Edge bioinformatics pipeline was designed based on following USE CASES and specific to illumina sequencing reads. 1. Assay performance adjudication (PCR): Analysis of an existing PCR assay in amore » genomic context, and automated design of a new assay to resolve conflicting results; 2. Clinical presentation with extreme symptoms: Characterization of a known pathogen or co-infection with a. Novel emerging disease outbreak or b. Environmental surveillance« less

  14. Edge Bioinformatics

    SciTech Connect

    Lo, Chien-Chi

    2015-08-03

    Edge Bioinformatics is a developmental bioinformatics and data management platform which seeks to supply laboratories with bioinformatics pipelines for analyzing data associated with common samples case goals. Edge Bioinformatics enables sequencing as a solution and forward-deployed situations where human-resources, space, bandwidth, and time are limited. The Edge bioinformatics pipeline was designed based on following USE CASES and specific to illumina sequencing reads. 1. Assay performance adjudication (PCR): Analysis of an existing PCR assay in a genomic context, and automated design of a new assay to resolve conflicting results; 2. Clinical presentation with extreme symptoms: Characterization of a known pathogen or co-infection with a. Novel emerging disease outbreak or b. Environmental surveillance

  15. Spectral characterization of the LANDSAT-D multispectral scanner subsystems

    NASA Technical Reports Server (NTRS)

    Markham, B. L. (Principal Investigator); Barker, J. L.

    1982-01-01

    Relative spectral response data for the multispectral scanner subsystems (MSS) to be flown on LANDSAT-D and LANDSAT-D backup, the protoflight and flight models, respectively, are presented and compared to similar data for the Landsat 1,2, and 3 subsystems. Channel-bychannel (six channels per band) outputs for soil and soybean targets were simulated and compared within each band and between scanners. The two LANDSAT-D scanners proved to be nearly identical in mean spectral response, but they exhibited some differences from the previous MSS's. Principal differences between the spectral responses of the D-scanners and previous scanners were: (1) a mean upper-band edge in the green band of 606 nm compared to previous means of 593 to 598 nm; (2) an average upper-band edge of 697 nm in the red band compared to previous averages of 701 to 710 nm; and (3) an average bandpass for the first near-IR band of 702-814 nm compared to a range of 693-793 to 697-802 nm for previous scanners. These differences caused the simulated D-scanner outputs to be 3 to 10 percent lower in the red band and 3 to 11 percent higher in the first near-IR band than previous scanners for the soybeans target. Otherwise, outputs from soil and soybean targets were only slightly affected. The D-scanners were generally more uniform from channel to channel within bands than previous scanners.

  16. [Research on spectral reflectance characteristics for Glycyrrhizae Radix].

    PubMed

    Li, Hui; Xie, Cai-Xiang; Li, Xiao-Jin; Wen, Mei-Jia; Jia, Guang-Lin; Shi, Ming-Hui; Guo, Bao-Lin; Jia, Xiao-Guang

    2014-02-01

    In order to study the spectral reflectance differences of Glycyrrhizae Radix under different growth conditions and lay the foundation for quantitative monitoring of Glycyrrhizae Radix remote sensing images, spectra of Glycyrrhiza species under different growth period and different varieties and different regions were measured by a portable spectrometer. The results showed that the reflectivity of annual G. uralensis was obviously higher than that of the two years plant in the visible light band own to the contents of crown layer chlorophyll. The reflectivity of two years G. pallidiflora was higher than that of G. uralensis in the near infrared band own to the leaf area index and the content of leaf water. The red edge spectrum of annual plant fluctuated largely than that of two years plant due to vegetation coverage and leaf area index. G. pallidiflora grew well than G. uralensis. Under different regions of the Glycyrrhiza species, spectral data analysis showed that within a certain range, the average annual precipitation and average annual evaporation were the major factors to affect the differences of Glycyrrhiza species spectral data under different regions owe to the leaf water content, the higher leaf water content, the lower spectral reflectance. The principal component analysis and continuum-removed method of the spectral data under different regions found that, within a certain range, the average annual precipitation and average annual evaporation were the major factors caused by the differences of Glycyrrhiza species spectral data under the different regions, Glycyrrhiza species spectral similarity related to the spatial distance. PMID:24946542

  17. Spectral edge: gradient-preserving spectral mapping for image fusion.

    PubMed

    Connah, David; Drew, Mark S; Finlayson, Graham D

    2015-12-01

    This paper describes a novel approach to image fusion for color display. Our goal is to generate an output image whose gradient matches that of the input as closely as possible. We achieve this using a constrained contrast mapping paradigm in the gradient domain, where the structure tensor of a high-dimensional gradient representation is mapped exactly to that of a low-dimensional gradient field which is then reintegrated to form an output. Constraints on output colors are provided by an initial RGB rendering. Initially, we motivate our solution with a simple "ansatz" (educated guess) for projecting higher-D contrast onto color gradients, which we expand to a more rigorous theorem to incorporate color constraints. The solution to these constrained optimizations is closed-form, allowing for simple and hence fast and efficient algorithms. The approach can map any N-D image data to any M-D output and can be used in a variety of applications using the same basic algorithm. In this paper, we focus on the problem of mapping N-D inputs to 3D color outputs. We present results in five applications: hyperspectral remote sensing, fusion of color and near-infrared or clear-filter images, multilighting imaging, dark flash, and color visualization of magnetic resonance imaging diffusion-tensor imaging. PMID:26831392

  18. [Spectral characteristics of Pinus tabulaeformis canopy with different damaged rates of needle leaf in western Liaoning Province, Northeast China].

    PubMed

    Feng, Rui; Zhang, Yu-Shu; Yu, Wen-Ying; Wu, Jin-Wen; Wang, Pei-Juan; Ji, Rui-Peng; Che, Yu-Sheng; Zhu, Yong-Ning

    2012-07-01

    Through the measurement of the spectral reflectance of large areas Chinese pine (Pinus tabulaeformis Carr. ) canopy in western Liaoning Province, this paper analyzed the difference of the spectral reflectance of the canopies with different damaged rates of needle leaf. In visible band, the characteristics of the spectral reflectance of P. tabulaeformis canopies with healthy and damaged needle leaf were in accordance with the spectral characteristics of green plants, but the position of red valley was not obvious when the damaged rate of needle leaf was higher than 60%. In near-infrared band, with the decrease of the damaged rate of needle leaf, the canopy spectral reflectance increased at 780-1350 nm, but decreased at 1450-1800 and 1950-2350 nm. With the increase of the damaged rate, the position of red-edge inflection moved to the short-wave direction. There were significant correlations between the damaged rate of needle leaf and the red edge feature variables and some vegetation indices. The model based on DVI (1470, 860) could be more reliable for predicting the damaged rate of needle leaf in P. tabulaeformis canopy in western Liaoning Province. PMID:23173448

  19. Defect correlated fluorescent quenching and electron phonon coupling in the spectral transition of Eu{sup 3+} in CaTiO{sub 3} for red emission in display application

    SciTech Connect

    Som, S. E-mail: swarthc@ufs.ac.za; Kumar, Vinod; Kumar, Vijay; Terblans, J. J.; Swart, H. C. E-mail: swarthc@ufs.ac.za; Kunti, A. K.; Dutta, S.; Chowdhury, M.; Sharma, S. K.

    2014-05-21

    This paper reports on the defect correlated self-quenching and spectroscopic investigation of calcium titanate (CaTiO{sub 3}) phosphors. A series of CaTiO{sub 3} phosphors doped with trivalent europium (Eu{sup 3+}) and codoped with potassium (K{sup +}) ions were prepared by the solid state reaction method. The X-ray diffraction results revealed that the obtained powder phosphors consisted out of a single-phase orthorhombic structure and it also indicated that the incorporation of the dopants/co-dopants did not affect the crystal structure. The scanning electron microscopy images revealed the irregular morphology of the prepared phosphors consisting out of μm sized diameter particles. The Eu{sup 3+} doped phosphors illuminated with ultraviolet light showed the characteristic red luminescence corresponding to the {sup 5}D{sub 0}→{sup 7}F{sub J} transitions of Eu{sup 3+}. As a charge compensator, K{sup +} ions were incorporated into the CaTiO{sub 3}:Eu{sup 3+} phosphors, which enhanced the photoluminescence (PL) intensities depending on the doping concentration of K{sup +}. The concentration quenching of Eu{sup 3+} in this host is discussed in the light of ion-ion interaction, electron phonon coupling, and defect to ion energy transfer. The spectral characteristics and the Eu-O ligand behaviour were determined using the Judd-Ofelt theory from the PL spectra instead of the absorption spectra. The CIE (International Commission on Illumination) parameters were calculated using spectral energy distribution functions and McCamy's empirical formula. Photometric characterization indicated the suitability of K{sup +} compensated the CaTiO{sub 3}:Eu{sup 3+} phosphor for pure red emission in light-emitting diode applications.

  20. The potential of Sentinel-2 spectral configuration to assess rangeland quality

    NASA Astrophysics Data System (ADS)

    Ramoelo, Abel; Cho, Moses; Mathieu, Renaud; Skidmore, Andrew K.

    2014-10-01

    The European Space Agency (ESA) has embarked on the development of the Sentinel constellation. Sentinel-2 is intended to improve vegetation assessment at local to global scale. Rangeland quality assessment is crucial for planning and management of grazing areas. Well managed and improved grazing areas lead to higher livestock production, which is a pillar of the rural economy and livelihoods, especially in many parts of the African continent. Leaf nitrogen (N) is an indicator of rangeland quality, and is crucial for understanding ecosystem function and services. Today, estimation of leaf N is possible using field and imaging spectroscopy. However, a few studies based on commercially available multispectral imageries such as WorldView-2 and RapidEye have shown the potential of a red-edge band for accurately predicting and mapping leaf N at the broad landscape scale. Sentinel-2 has two red edge bands. The objective of this study was to investigate the utility of the spectral configuration of Sentinel-2 for estimating leaf N concentration in rangelands and savannas of Southern Africa. Grass canopy reflectance was measured using the FieldSpec 3, Analytical Spectral Device (ASD) in concert with leaf sample collections for leaf N chemical analysis. ASD reflectances were resampled to the spectral bands of Sentinel-2 using published spectral response functions. Random Forest (RF) technique was used to predict leaf N using all thirteen bands. Using leave-one-out cross validation, the RF model explained 90% of leaf N variation, with the root mean square error (RMSE) of 0.04 (6% of the mean). Interestingly, spectral bands centred at 705 nm (red edge) and two shortwave infrared centred at 2190 and 1610 nm were found to be the most important bands in predicting leaf N. These findings concur with previous studies based on spectroscopy, airborne hyperspectral or multispectral imagery, e.g. RapidEye, on the importance of shortwave infrared and red-edge reflectance in the

  1. Comparative study of Er3+ and Tm3+ co-doped YOF and Y2O3 powders as red spectrally pure upconverters

    NASA Astrophysics Data System (ADS)

    Rakov, Nikifor; Maciel, Glauco S.

    2013-10-01

    We prepared Er3+ and Tm3+ co-doped yttrium oxyfluoride (YOF) powder by combustion synthesis and we observed that under near-infrared (λ = 980 nm) laser excitation the characteristic green (2H11/2, 4S3/2 → 4I15/2) emission of Er3+ was suppressed by energy transfer (ET) mechanisms between Tm3+ and Er3+. The ET process observed in YOF was much more efficient than that observed in standard Y2O3 powder prepared under similar conditions. YOF combines the superior mechanical and thermal properties of oxides with low phonon energy of fluorides. Our results show that this material is a serious candidate for use as a red upconversion phosphor.

  2. An ellipse detection algorithm based on edge classification

    NASA Astrophysics Data System (ADS)

    Yu, Liu; Chen, Feng; Huang, Jianming; Wei, Xiangquan

    2015-12-01

    In order to enhance the speed and accuracy of ellipse detection, an ellipse detection algorithm based on edge classification is proposed. Too many edge points are removed by making edge into point in serialized form and the distance constraint between the edge points. It achieves effective classification by the criteria of the angle between the edge points. And it makes the probability of randomly selecting the edge points falling on the same ellipse greatly increased. Ellipse fitting accuracy is significantly improved by the optimization of the RED algorithm. It uses Euclidean distance to measure the distance from the edge point to the elliptical boundary. Experimental results show that: it can detect ellipse well in case of edge with interference or edges blocking each other. It has higher detecting precision and less time consuming than the RED algorithm.

  3. NLTE and LTE Lick Indices for Red Giants from [Fe/H] 0.0 to -6.0 at SDSS and IDS Spectral Resolution

    NASA Astrophysics Data System (ADS)

    Short, C. Ian; Young, Mitchell E.; Layden, Nicholas

    2015-09-01

    We investigate the dependence of the complete system of 22 Lick indices on overall metallicity scaled from solar abundances, [{{M}}/{{H}}], from the solar value, 0.0, down to the extremely metal-poor (XMP) value of -6.0, for late-type giant stars (MK luminosity class III, {log}g=2.0) of MK spectral class late-K to late-F (3750\\lt {T}{eff}\\lt 6500 K) of the type that are detected as “fossils” of early galaxy formation in the Galactic halo and in extra-galactic structures. Our investigation is based on synthetic index values, I, derived from atmospheric models and synthetic spectra computed with PHOENIX in Local Thermodynamic Equilibrium (LTE) and Non-LTE (NLTE), where the synthetic spectra have been convolved to the spectral resolution, R, of both IDS and SDSS (and LAMOST) spectroscopy. We identify nine indices, that we designate “Lick-XMP,” that remain both detectable and significantly [{{M}}/{{H}}]-dependent down to [{{M}}/{{H}}] values of at least ˜ -5.0, and down to [{{M}}/{{H}}] ˜ -6.0 in five cases, while also remaining well-behaved (single-valued as a function of [{{M}}/{{H}}] and positive in linear units). For these nine indices, we study the dependence of I on NLTE effects, and on spectral resolution. For our LTE I values for spectra of SDSS resolution, we present the fitted polynomial coefficients, {C}{{n}}, from multi-variate linear regression for I with terms up to third order in the independent variable pairs ({T}{eff}, [{{M}}/{{H}}] ) and (V-K, [{{M}}/{{H}}]), and compare them to the fitted {C}{{n}} values of Worthey et al. at IDS spectral resolution. For this fitted I data-set we present tables of LTE partial derivatives, \\frac{\\partial I}{\\partial {T}{eff}}{| }[{{M}/{{H}}]}, \\frac{\\displaystyle \\partial I}{\\partial [{{M}}/{{H}}]}{| }{T{eff}}, \\frac{\\displaystyle \\partial I}{\\partial (V-K)}{| }[{{M}/{{H}}]}, and \\frac{\\partial I}{\\partial [{{M}}/{{H}}]}{| }(V-K), that can be used to infer the relation between a given

  4. Edge detection

    NASA Astrophysics Data System (ADS)

    Hildreth, E. C.

    1985-09-01

    For both biological systems and machines, vision begins with a large and unwieldly array of measurements of the amount of light reflected from surfaces in the environment. The goal of vision is to recover physical properties of objects in the scene such as the location of object boundaries and the structure, color and texture of object surfaces, from the two-dimensional image that is projected onto the eye or camera. This goal is not achieved in a single step: vision proceeds in stages, with each stage producing increasingly more useful descriptions of the image and then the scene. The first clues about the physical properties of the scene are provided by the changes of intensity in the image. The importance of intensity changes and edges in early visual processing has led to extensive research on their detection, description and use, both in computer and biological vision systems. This article reviews some of the theory that underlies the detection of edges, and the methods used to carry out this analysis.

  5. Reduction of airfoil trailing edge noise by trailing edge blowing

    NASA Astrophysics Data System (ADS)

    Gerhard, T.; Erbslöh, S.; Carolus, T.

    2014-06-01

    The paper deals with airfoil trailing edge noise and its reduction by trailing edge blowing. A Somers S834 airfoil section which originally was designed for small wind turbines is investigated. To mimic realistic Reynolds numbers the boundary layer is tripped on pressure and suction side. The chordwise position of the blowing slot is varied. The acoustic sources, i.e. the unsteady flow quantities in the turbulent boundary layer in the vicinity of the trailing edge, are quantified for the airfoil without and with trailing edge blowing by means of a large eddy simulation and complementary measurements. Eventually the far field airfoil noise is measured by a two-microphone filtering and correlation and a 40 microphone array technique. Both, LES-prediction and measurements showed that a suitable blowing jet on the airfoil suction side is able to reduce significantly the turbulence intensity and the induced surface pressure fluctuations in the trailing edge region. As a consequence, trailing edge noise associated with a spectral hump around 500 Hz could be reduced by 3 dB. For that a jet velocity of 50% of the free field velocity was sufficient. The most favourable slot position was at 90% chord length.

  6. Temporal registration of multispectral digital satellite images using their edge images

    NASA Technical Reports Server (NTRS)

    Nack, M. L.

    1975-01-01

    An algorithm is described which will form an edge image by detecting the edges of features in a particular spectral band of a digital satellite image. It is capable also of forming composite multispectral edge images. In addition, an edge image correlation algorithm is presented which performs rapid automatic registration of the edge images and, consequently, the grey level images.

  7. The Edge

    NASA Technical Reports Server (NTRS)

    2006-01-01

    6 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the edge (running diagonally from the lower left to the upper right) of a trough, which is part of a large pit crater complex in Noachis Terra. This type of trough forms through the collapse of surface materials into the subsurface, and often begins as a series of individual pit craters. Over time, continued collapse increases the diameter of individual pits until finally, adjacent pits merge to form a trough such as the one captured in this image. The deep shadowed area is caused in part by an overhang; layered rock beneath this overhang is less resistant to erosion, and thus has retreated tens of meters backward, beneath the overhang. A person could walk up inside this 'cave' formed by the overhanging layered material.

    Location near: 47.0oS, 355.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  8. Edge-based correlation image registration for multispectral imaging

    DOEpatents

    Nandy, Prabal

    2009-11-17

    Registration information for images of a common target obtained from a plurality of different spectral bands can be obtained by combining edge detection and phase correlation. The images are edge-filtered, and pairs of the edge-filtered images are then phase correlated to produce phase correlation images. The registration information can be determined based on these phase correlation images.

  9. [Extraction of spectral difference characteristics of Stellera chamaejasme in Qilian County of Qinghai Province, Northwest China].

    PubMed

    Cheng, Di; Liu, Yong-mei; Li, Jing-zhong; Mo, Chong-hui

    2015-08-01

    Stellera chamaejasme is one of the main poisonous weeds distributed in alpine meadow of Qinghai Province. Rapid spreading of S. chamaejasme has done serious harm to local animal husbandry and caused continuous grassland ecosystem degradation. This paper focused on the spectral differences between S. chamaejasme and herbage, taking the typical degraded alpine meadow dominated by S. chamaejasme in Qilian County of Haibei Region as the test site and using the spectral measurements acquired in the full-blossom period of S. chamaejasme from 2012 to 2014. The results showed that the spectral behavior of flowers of S. chamaejasme differed significantly from green background that included leaves of S. chamaejasme and herbage within 350-900 nm of VIS-NIR wavebands. The biggest reflectance difference between flowers of S. chamaejasme and green background was located in the red valley, followed by the blue valley. The reflectance of S. chamaejasme community increased with the rising of coverage, the biggest reflectance difference between S. chamaejasme and herbage communities lied in the near-infrared peak, and the best separability between S. chamaejasme communities with different coverage was also at the point. The difference of first derivative spectra between flowers of S. chamaejasme and green background located in amplitude of yellow edge was remarkable, followed by amplitude of blue edge, the same as differences between S. chamaejasme and herbage communities. Linear regression analysis between coverage of S. chamaejasme and spectral feature parameters showed best result for red valley (R2 = 0.94). Finally, the red valley, the blue valley and the near-infrared peak were proposed for discriminating S. chamaejasme from herbage in the full-blossom period of S. chamaejasme, and the combination of corresponding red, blue and near-infrared bands could be used to build sensitive indices for S. chamaejasme recognition. PMID:26685592

  10. Unified EDGE

    SciTech Connect

    2007-06-18

    UEDGE is an interactive suite of physics packages using the Python or BASIS scripting systems. The plasma is described by time-dependent 2D plasma fluid equations that include equations for density, velocity, ion temperature, electron temperature, electrostatic potential, and gas density in the edge region of a magnetic fusion energy confinement device. Slab, cylindrical, and toroidal geometries are allowed, and closed and open magnetic field-line regions are included. Classical transport is assumed along magnetic field lines, and anomalous transport is assumed across field lines. Multi-charge state impurities can be included with the corresponding line-radiation energy loss. Although UEDGE is written in Fortran, for efficient execution and analysis of results, it utilizes either Python or BASIS scripting shells. Python is easily available for many platforms (http://www.Python.org/). The features and availability of BASIS are described in “Basis Manual Set” by P.F. Dubois, Z.C. Motteler, et al., Lawrence Livermore National Laboratory report UCRL-MA-1 18541, June, 2002 and http://basis.llnl.gov. BASIS has been reviewed and released by LLNL for unlimited distribution. The Python version utilizes PYBASIS scripts developed by D.P. Grote, LLNL. The Python version also uses MPPL code and MAC Perl script, available from the public-domain BASIS source above. The Forthon version of UEDGE uses the same source files, but utilizes Forthon to produce a Python-compatible source. Forthon has been developed by D.P. Grote at LBL (see http://hifweb.lbl.gov/Forthon/ and Grote et al. in the references below), and it is freely available. The graphics can be performed by any package importable to Python, such as PYGIST.

  11. Unified EDGE

    Energy Science and Technology Software Center (ESTSC)

    2007-06-18

    UEDGE is an interactive suite of physics packages using the Python or BASIS scripting systems. The plasma is described by time-dependent 2D plasma fluid equations that include equations for density, velocity, ion temperature, electron temperature, electrostatic potential, and gas density in the edge region of a magnetic fusion energy confinement device. Slab, cylindrical, and toroidal geometries are allowed, and closed and open magnetic field-line regions are included. Classical transport is assumed along magnetic field lines,more » and anomalous transport is assumed across field lines. Multi-charge state impurities can be included with the corresponding line-radiation energy loss. Although UEDGE is written in Fortran, for efficient execution and analysis of results, it utilizes either Python or BASIS scripting shells. Python is easily available for many platforms (http://www.Python.org/). The features and availability of BASIS are described in “Basis Manual Set” by P.F. Dubois, Z.C. Motteler, et al., Lawrence Livermore National Laboratory report UCRL-MA-1 18541, June, 2002 and http://basis.llnl.gov. BASIS has been reviewed and released by LLNL for unlimited distribution. The Python version utilizes PYBASIS scripts developed by D.P. Grote, LLNL. The Python version also uses MPPL code and MAC Perl script, available from the public-domain BASIS source above. The Forthon version of UEDGE uses the same source files, but utilizes Forthon to produce a Python-compatible source. Forthon has been developed by D.P. Grote at LBL (see http://hifweb.lbl.gov/Forthon/ and Grote et al. in the references below), and it is freely available. The graphics can be performed by any package importable to Python, such as PYGIST.« less

  12. Spectral changes in conifers subjected to air pollution and water stress: Experimental studies

    NASA Technical Reports Server (NTRS)

    Westman, Walter E.; Price, Curtis V.

    1988-01-01

    The roles of leaf anatomy, moisture and pigment content, and number of leaf layers on spectral reflectance in healthy, pollution-stressed, and water-stressed conifer needles were examined experimentally. Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were exposed to ozone and acid mist treatments in fumigation chambers; red pine (Pinus resinosa) needles were artificially dried. Infrared reflectance from stacked needles rose with free water loss. In an air-drying experiment, cell volume reductions induced by loss of turgor caused near-infrared reflectance (TM band 4) to drop after most free water was lost. Under acid mist fumigation, stunting of tissue development similarly reduced band 4 reflectance. Both artificial drying and pollutant fumigation caused a blue shift of the red edge of spectral reflectance curves in conifers, attributable to chlorophyll denaturation. Thematic mapper band ratio 4/3 fell and 5/4 rose with increasing pollution stress on artificial drying. Loss of water by air-drying, freeze-drying, or oven-drying enhanced spectral features, due in part to greater scattering and reduced water absorption. Grinding of the leaf tissue further enhanced the spectral features by increasing reflecting surfaces and path length. In a leaf-stacking experiment, an asymptote in visible and infrared reflectance was reached at 7-8 needle layers of red pine.

  13. [Change of LAI and spectral response for rice under flood and waterlogging stress].

    PubMed

    Xu, Peng; Gu, Xiao-He; Meng, Lu-Min; Qiu, He; Wang, Hui-Fang

    2013-12-01

    In order to provide the foundational theoretical support for flood loss estimation of rice with RS, the change of leaf area index (LAI) and canopy spectral response during four developmental stages and three waterlogging depths were studied, and the LAI estimation model was established with spectra characteristics parameter using regression analysis method. The results show that LAI value decreases as water depth increases in tillering, jointing and heading stages, and LAI value under complete submergence decreased by 36. 36% than CK in jointing stages. "Double-Peak" presented in the canopy first derivative spectra of 680-760 nm where the red edge parameters existed, and the main peak is located in the 724-737 nm with 701 and 718 nm exhibiting secondary peak. With water depth increasing, "Triple-Peak" emerges especially. The red edge position moves to long-wavelength direction in each developmental stage. Blue shift of red edge amplitude and red edge area was detected in tillering, jointing and filling stages, while red shift appeared in heading stage. The relationship between spectra characteristics parameters and LAI were investigated during 4 growth stages, results were not consistently significant at any wavelengths, and the leaf area indices were significantly correlative to the spectra parameters before heading stage, so the spectra parameters before heading stage can be used to estimate the leaf area indices, and a regression model based on parameter D(lambda737)/D(lambda718) was recommended. Therefore the variation range of LAI for rice could response to the stress intensity directly, and the regression model LAI= 3. 138(D(lambda737)/D(lambda718))-0. 806 can precisely estimate the leaf area index under flooding and waterlogging stress. PMID:24611390

  14. Eye redness

    MedlinePlus

    Bloodshot eyes; Red eyes; Scleral infection; Conjunctival infection ... There are many causes of a red eye or eyes. Some are medical emergencies and some are a cause for concern, but not an emergency. Others are nothing to worry about. ...

  15. Red Clover

    MedlinePlus

    ... 17):2057–2071. Red clover. Natural Medicines Comprehensive Database Web site. Accessed at www.naturaldatabase.com on July 22, 2009. Red clover ( Trifolium pratense ). Natural Standard Database Web site. Accessed at www.naturalstandard.com on July ...

  16. Red clover

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red clover (Trifolium pratense L.) is an important forage legume grown on approximately 4 million hectares worldwide. An estimated 2.8 million kg of red clover seed per year was produced worldwide in 2005-2007. This amount of seed would be enough to maintain approximately 4 million hectares of red...

  17. Red Sea

    Atmospheric Science Data Center

    2013-04-16

    article title:  The Red Sea     View Larger Image ... Imaging SpectroRadiometer (MISR) image of the Red Sea was acquired on August 13, 2000. Located between the East African coast and the Saudi Arabian peninsula, the Red Sea got its name because the blooms of a type of algae,  Trichodesmium ...

  18. Seeing Red

    NASA Technical Reports Server (NTRS)

    2008-01-01

    volcanos. Though the plume deposits are red, the plume itself is blue, because it is composed of very tiny particles that preferentially scatter blue light, like smoke. Also faintly visible in the left image is the pale-colored Prometheus plume, almost on the edge of the disk on the equator at the 9 o'clock position.

    Io was 2.4 million kilometers from the spacecraft when the picture was taken, and the center of Io's disk is at 77 degrees West longitude, 5 degrees South latitude. The solar phase angle was 107 degrees.

  19. TCT measurements with slim edge strip detectors

    NASA Astrophysics Data System (ADS)

    Mandić, Igor; Cindro, Vladimir; Gorišek, Andrej; Kramberger, Gregor; Mikuž, Marko; Zavrtanik, Marko; Fadeyev, Vitaliy; Sadrozinski, Hartmut F.-W.; Christophersen, Marc; Phlips, Bernard

    2014-07-01

    Transient current technique (TCT) measurements with focused laser light on miniature silicon strip detectors (n+-type strips on p-type bulk) with one inactive edge thinned to about 100 μm using the Scribe-Cleave-Passivate (SCP) method are presented. Pulses of focused IR (λ=1064 nm) laser light were directed to the surface of the detector and charge collection properties near the slim edge were investigated. Measurements before and after irradiation with reactor neutrons up to 1 MeV equivalent fluence of 1.5×1015 neq/cm2 showed that SCP thinning of detector edge does not influence its charge collection properties. TCT measurements were done also with focused red laser beam (λ=640 nm) directed to the SCP processed side of the detector. The absorption length of red light in silicon is about 3 μm so with this measurement information about the electric field at the edge can be obtained. Observations of laser induced signals indicate that the electric field distribution along the depth of the detector at the detector edge is different than in the detector bulk: electric field is higher near the strip side and lower at the back side. This is a consequence of negative surface charge caused by passivation of the cleaved edge with Al2O3. The difference between bulk and edge electric field distributions gets smaller after irradiation.

  20. Spectral Reflectance and Vegetation Index Changes in Deciduous Forest Foliage Following Tree Removal: Potential for Deforestation Monitoring

    NASA Astrophysics Data System (ADS)

    Peng, D.; Hu, Y.; Li, Z.

    2016-05-01

    It is important to detect and quantify deforestation to guide strategic decisions regarding environment, socioeconomic development, and climate change. In the present study, we conducted a field experiment to examine spectral reflectance and vegetation index changes in poplar and locust tree foliage with different leaf area indices over the course of three sunny days, following tree removal from the canopy. The spectral reflectance of foliage from harvested trees was measured using an ASD FieldSpec Prospectroradiometer; synchronous meteorological data were also obtained. We found that reflectance in short-wave infrared and red-edge reflectance was more time sensitive after tree removal than reflectance in other spectral regions, and that the normalized difference water index (NDWI) and the red-edge chlorophyll index (CIRE) were the preferred indicators of these changes from several indices evaluated. Synthesized meteorological environments were found to influence water and chlorophyll contents after tree removal, and this subsequently changed the spectral canopy reflectance. Our results indicate the potential for such tree removal to be detected with NDWI or CIRE from the second day of a deforestation event.

  1. Spectroscopy of red dravite from northern Tanzania

    NASA Astrophysics Data System (ADS)

    Taran, Michail N.; Dyar, M. Darby; Naumenko, Ievgen V.; Vyshnevsky, Olexij A.

    2015-07-01

    Low-Fe dravite with a formula of Na0.66Ca0.16Mg2.62Fe0.33Mn0.02Ti0.02Al5.95B3Si6.04O27(OH)4 is described from Engusero Sambu, northern Tanzania (On maps, Engusero Sambu may be found to be marked as belonging to Kenya, but in reality, it is located near the border in northern Tanzania). The sample has an unusual red color that is distinctly different from the red dravite from the Osarara, Narok district, in Kenya that was formerly studied by Mattson and Rossman (Phys Chem Miner 14:225-234, 1984) and Taran and Rossman (Am Mineral 87:1148-1153, 2002). This unique sample has been characterized by optical and Mössbauer spectral measurements to investigate underlying cause of the intense bands in absorption spectra that give rise to the red color. These features are shown to be caused by exchange-coupled Fe3+-Fe3+ interactions. Thermal annealing of the samples causes an increase in Fe3+ contents due to oxidation of [Y]Fe2+. However, heat treatment does not change the high-energy absorption edge, which is probably caused by intense ligand-to-Fe3+ charge-transfer UV bands. In fact, Mössbauer results show that high-temperature annealing initiates breakdown of the tourmaline into an Fe oxide and causes accompanying redistribution of Fe3+ within the structure. Because of the popularity of tourmaline as a gemstone, this work has implications for understanding the causes of color in tourmaline, facilitating recognition of the distinctions between naturally occurring and treated tourmalines in the gem industry and enabling heat treatments for color enhancement.

  2. [The canopy and leaf spectral characteristics and nutrition diagnosis of tomato in greenhouse].

    PubMed

    Zhao, Rui-jiao; Li, Min-zan; Yang, Ce; Yang, Wei; Sun, Hong

    2010-11-01

    .7511. Meanwhile, red edge inflection points were analyzed under four nutrition treatments based on the first derivative of canopy spectral reflectance. The analysis results illustrated that red edge inflection position moved to direction of red light (long wavelength) with the nutrition supply. PMID:21284192

  3. Spectral characterization of the LANDSAT thematic mapper sensors

    NASA Technical Reports Server (NTRS)

    Markham, B. L.; Barker, J. L.

    1983-01-01

    Data collected on the spectral characteristics of the LANDSAT-4 and LANDSAT-4 backup thematic mapper instruments, the protoflight (TM/PF) and flight (TM/F) models, respectively, are presented and analyzed. Tests were conducted on the instruments and their components to determine compliance with two sets of spectral specifications: band-by-band spectral coverage and channel-by-channel within-band spectral matching. Spectral coverage specifications were placed on: (1) band edges--points at 50% of peak response, (2) band edge slopes--steepness of rise and fall-off of response, (3) spectral flatness--evenness of response between edges, and (4) spurious system response--ratio of out-of-band response to in-band response. Compliance with the spectral coverage specifications was determined by analysis of spectral measurements on the individual components contributing to the overall spectral response: filters, detectors, and optical surfaces.

  4. The edges of graphene.

    PubMed

    Zhang, Xiuyun; Xin, John; Ding, Feng

    2013-04-01

    The edge of two dimensional (2D) graphene, as the surface of a three dimensional (3D) crystal, plays a crucial role in the determination of its physical, electronic and chemical properties and thus has been extensively studied recently. In this review, we summarize the recent advances in the study of graphene edges, including edge formation energy, edge reconstruction, method of graphene edge synthesis and the recent progress on metal-passivated graphene edges and the role of edges in graphene CVD growth. We expect this review to provide a guideline for readers to gain a clear picture of graphene edges from several aspects, especially the catalyst-passivated graphene edges and their role in graphene CVD growth. PMID:23420074

  5. The edges of graphene

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuyun; Xin, John; Ding, Feng

    2013-03-01

    The edge of two dimensional (2D) graphene, as the surface of a three dimensional (3D) crystal, plays a crucial role in the determination of its physical, electronic and chemical properties and thus has been extensively studied recently. In this review, we summarize the recent advances in the study of graphene edges, including edge formation energy, edge reconstruction, method of graphene edge synthesis and the recent progress on metal-passivated graphene edges and the role of edges in graphene CVD growth. We expect this review to provide a guideline for readers to gain a clear picture of graphene edges from several aspects, especially the catalyst-passivated graphene edges and their role in graphene CVD growth.

  6. Effect of spectrally varying albedo of vegetation surfaces on shortwave radiation fluxes and direct aerosol forcing

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Martins, J. V.; Yu, H.

    2012-06-01

    This study develops an algorithm for the representation of large spectral variations of albedo over vegetation surfaces based on Moderate Resolution Imaging Spectrometer (MODIS) observations at 7 discrete channels centered at 0.47, 0.55, 0.67, 0.86, 1.24, 1.63, and 2.11 μm. The MODIS 7-channel observations miss several major features of vegetation albedo including the vegetation red edge near 0.7 μm and vegetation absorption features at 1.48 and 1.92 μm. We characterize these features by investigating aerosol forcing in different spectral ranges. We show that the correction at 0.7 μm is the most sensitive and important due to the presence of the red edge and strong solar radiation; the other two corrections are less sensitive due to the weaker solar radiation and strong atmospheric water absorption. Four traditional approaches for estimating the reflectance spectrum and the MODIS enhanced vegetation albedo (MEVA) are tested against various vegetation types: dry grass, green grass, conifer, and deciduous from the John Hopkins University (JHU) spectral library; aspens from the US Geological Survey (USGS) digital spectral library; and Amazon vegetation types. Compared to traditional approaches, MEVA improves the accuracy of the outgoing flux at the top of the atmosphere by over 60 W m-2 and aerosol forcing by over 10 W m-2. Specifically, for Amazon vegetation types, MEVA can improve the accuracy of daily averaged aerosol forcing at equator at equinox by 3.7 W m-2 (about 70% of the aerosol forcing calculated with high spectral resolution surface reflectance). These improvements indicate that MEVA can contribute to vegetation covered regional climate studies, and help to improve understanding of climate processes and climate change.

  7. Brown and green LAI mapping through spectral indices

    NASA Astrophysics Data System (ADS)

    Delegido, Jesús; Verrelst, Jochem; Rivera, Juan P.; Ruiz-Verdú, Antonio; Moreno, José

    2015-03-01

    When crops senescence, leaves remain until they fall off or are harvested. Hence, leaf area index (LAI) stays high even when chlorophyll content degrades to zero. Current LAI approaches from remote sensing techniques are not optimized for estimating LAI of senescent vegetation. In this paper a two-step approach has been proposed to realize simultaneous LAI mapping over green and senescent croplands. The first step separates green from brown LAI by means of a newly proposed index, 'Green Brown Vegetation Index (GBVI)'. This index exploits two shortwave infrared (SWIR) spectral bands centred at 2100 and 2000 nm, which fall right in the dry matter absorption regions, thereby providing positive values for senescent vegetation and negative for green vegetation. The second step involves applying linear regression functions based on optimized vegetation indices to estimate green and brown LAI estimation respectively. While the green LAI index uses a band in the red and a band in the red-edge, the brown LAI index uses bands located in the same spectral region as GBVI, i.e. an absorption band located in the region of maximum absorption of cellulose and lignin at 2154 nm, and a reference band at 1635 nm where the absorption of both water and dry matter is low. The two-step approach was applied to a HyMap image acquired over an agroecosystem at the agricultural site Barrax, Spain.

  8. Spectral and Spread Spectral Teleportation

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  9. The spectral and image characteristics of vegetation in the presence of heavy metals in southern China

    NASA Astrophysics Data System (ADS)

    Yang, Fengjie; Li, Na; Zhou, Guangzhu; Song, Cuiyu; Li, Qingting

    2008-10-01

    The principle and methodology to monitor the heavy metal pollution using hyperspectral remote sensing are put forward based on the study areas, copper mine in De-Xing and tin ore in GeJiu, and selected plants, China Sumac, Sweet Wormwood Herb, and Nephrolepis Cordifolia. In the areas defined by former information, vegetation samples and corresponding spectral data are gathered. The samples are then analyzed in chemical lab, telling us to what extent the vegetation is polluted by heavy metal. The spectral curves are also processed, and some spectral parameters are extracted, such as reflectance, blue-shift extent, position of red-edge, vegetation index, band-depth. Then the regression model from spectral characteristic parameters to heavy metal content can be built. At last, the conclusion can be attained. In copper mine area, the vegetation is polluted by seven kinds of heavy metals. As far as China Sumac, the reflectance of red band correlates the Pb content well. The reflectance of all study plants at 1240nm and 725/675(nm) correlates heavy metal content well. The reflectance of 450nm, 550nm, 670nm, 760nm, and 1240nm can be liner combined as a parameter to monitor heavy metal pollution. Besides, some band-depth can also be combined as parameters using "Enter". In a word, as an advanced technique to monitor environmental pollution, hyperspectral remote sensing has wild perspective.

  10. Effect of atomic density on propagation and spectral property of femtosecond chirped Gaussian pulses

    NASA Astrophysics Data System (ADS)

    Wang, Zhendong; Gao, Feng

    2015-05-01

    We theoretically investigate the effect of the atomic densities N on propagation and spectral property of femtosecond chirped Gaussian pulse in a three-level Λ-type atomic medium by using the numerical solution of the full Maxwell- Bloch equations. It is shown that, when the positive chirped pulse with area 3π, propagate in the medium with smaller N, pulse splitting doesn't occur and many small oscillations at the trailing edge of the pulse appear, in addition, the level |2< population ρ22 of the pulse exhibits an oscillation feature with time evolution, moreover, the spectral component near the central frequency of the pulse shows an oscillation characteristic too, and the propagation and spectral property of the negative chirped 3π pulse is very similar to that of the positive chirped 3π pulse. For the positive chirped 3π pulse pulses, propagate in the medium with larger N, pulse splitting also doesn't occur but many small oscillations both at leading edge and the trailing edge of the pulse appear, and the population ρ22 of the pulse only exhibits an scarcely oscillation feature with time evolution, at the same time many oscillations both in blue shift and red shift components of the pulse appear but the spectral component near the central frequency of the pulse oscillate more severely, and the propagation and spectral property of the negative chirped 3π pulse is very similar to that of the positive chirped 3π pulse, but comparing with the case of the negative chirped 3π pulse, the propagation of the positive chirped 3π pulse is delayed at the same distance and the delayed time becomes longer with the distance increasing.

  11. Red Sky with Red Mesa

    SciTech Connect

    2011-04-14

    The Red Sky/Red Mesa supercomputing platform dramatically reduces the time required to simulate complex fuel models, from 4-6 months to just 4 weeks, allowing researchers to accelerate the pace at which they can address these complex problems. Its speed also reduces the need for laboratory and field testing, allowing for energy reduction far beyond data center walls.

  12. Red Sky with Red Mesa

    ScienceCinema

    None

    2014-06-23

    The Red Sky/Red Mesa supercomputing platform dramatically reduces the time required to simulate complex fuel models, from 4-6 months to just 4 weeks, allowing researchers to accelerate the pace at which they can address these complex problems. Its speed also reduces the need for laboratory and field testing, allowing for energy reduction far beyond data center walls.

  13. Red Capes, Red Herrings, and Red Flags.

    ERIC Educational Resources Information Center

    Fiske, Donald W.

    The argument that the personality structures obtained from retrospective ratings reflect semantic similarity structures has been as provocative as a red cape in the bull ring. High congruence between those two kinds of structures seems well established. What is less clear is how and why those structures differ from that for immediate judgments of…

  14. Eye redness

    MedlinePlus

    ... Blepharitis : Swelling along the edge of the eyelid. Conjunctivitis : Swelling or infection of the clear tissue that ... Alvarenga LS, Ginsberg B, Mannis MJ.. Bacterial conjunctivitis. In: ... Williams & Wilkins; 2013:vol 4, chap 5. Rubenstein JB, Tannan ...

  15. [Vegetation index estimation by chlorophyll content of grassland based on spectral analysis].

    PubMed

    Xiao, Han; Chen, Xiu-Wan; Yang, Zhen-Yu; Li, Huai-Yu; Zhu, Han

    2014-11-01

    Comparing the methods of existing remote sensing research on the estimation of chlorophyll content, the present paper confirms that the vegetation index is one of the most practical and popular research methods. In recent years, the increasingly serious problem of grassland degradation. This paper, firstly, analyzes the measured reflectance spectral curve and its first derivative curve in the grasslands of Songpan, Sichuan and Gongger, Inner Mongolia, conducts correlation analysis between these two spectral curves and chlorophyll content, and finds out the regulation between REP (red edge position) and grassland chlorophyll content, that is, the higher the chlorophyll content is, the higher the REIP (red-edge inflection point) value would be. Then, this paper constructs GCI (grassland chlorophyll index) and selects the most suitable band for retrieval. Finally, this paper calculates the GCI by the use of satellite hyperspectral image, conducts the verification and accuracy analysis of the calculation results compared with chlorophyll content data collected from field of twice experiments. The result shows that for grassland chlorophyll content, GCI has stronger sensitivity than other indices of chlorophyll, and has higher estimation accuracy. GCI is the first proposed to estimate the grassland chlorophyll content, and has wide application potential for the remote sensing retrieval of grassland chlorophyll content. In addition, the grassland chlorophyll content estimation method based on remote sensing retrieval in this paper provides new research ideas for other vegetation biochemical parameters' estimation, vegetation growth status' evaluation and grassland ecological environment change's monitoring. PMID:25752061

  16. Species Discrimination of Mangroves using Derivative Spectral Analysis

    NASA Astrophysics Data System (ADS)

    Prasad, K. Arun; Gnanappazham, L.

    2014-11-01

    Mangroves are salt tolerant trees or shrubs commonly seen in mudflats of intertidal regions of tropical and subtropical coastlines. Recent advances in field spectroscopic techniques enabled the species level discrimination among closely related vegetation types. In this study we have analysed the laboratory spectroscopy data collected from eight species of Rhizophoraceaea family of mangroves. The spectral data ranges between the wavelength of 350 nm and 2500 nm at a very narrow bandwidth of 1 nm. Preprocessing techniques including smoothing were done on the spectra to remove the noise before compiling it to a spectral library. Derivative analysis of the spectra was done and its corresponding first and second derivatives were obtained. Statistical analysis such as parametric and non-parametric tests were implemented on the original processed spectra as well as their respective first and second order derivatives for the identification of significant bands for species discrimination. Results have shown that red edge region (680 nm - 720 nm) and water vapour absorption region around 1150 nm and 1400 nm are optimal as they were consistent in discriminating species in reflectance spectra as well as in its first and second derivative spectra. C. decandra species is found to be discriminable from other species while reflectance and its derivative spectra were used. Non-parametric statistical analysis gave better results than that of parametric statistical analysis especially in SWIR 2 spectral region (1831 nm - 2500 nm).

  17. Red Emitting VCSEL

    NASA Astrophysics Data System (ADS)

    Jetter, Michael; Roßbach, Robert; Michler, Peter

    This chapter describes the progress in development of vertical-cavity surface-emitting lasers (VCSEL) emitting in the red spectral region around 650 nm for data transmission over polymer optical fibers (POF). First, growth issues of red VCSEL using two different material systems, namely AlGaAs and AlGaInP, are introduced. In particular, the optical and electrical state-of-the-art characteristics as low threshold currents ({≤} 1 mA) and high output powers (several mW) are presented with a special focus on emission wavelength. Also the thermal budget and heat removal in the devices are pointed out with regard to the geometry of the VCSEL. Small-signal modulation response in terms of maximum resonance frequency in dependance on temperature behavior are discussed. Applications of these devices in optical interconnects are described and digital data transmission at data rates up to 2.1 Gbit/s over step-index POF is reported. These properties make red emitting VCSEL perfectly suited for high-speed low power consuming light sources for optical data communication via POF. By introducing InP quantum dots as gain material in red emitting VCSEL nearly temperature independent record low threshold current densities of around 10 A/cm2 could be observed.

  18. Spectral stratigraphy

    NASA Technical Reports Server (NTRS)

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  19. Edge-on Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA's Hubble Space Telescope has imaged an unusual edge-on galaxy, revealing remarkable details of its warped dusty disc and showing how colliding galaxies trigger the birth of new stars.

    The image, taken by Hubble's Wide Field and Planetary Camera 2 (WFPC2), is online at http://heritage.stsci.edu and http://www.jpl.nasa.gov/images/wfpc. The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. During observations of the galaxy, the camera passed a milestone, taking its 100,000th image since shuttle astronauts installed it in Hubble in 1993.

    The dust and spiral arms of normal spiral galaxies, like our Milky Way, look flat when seen edge- on. The new image of the galaxy ESO 510-G13 shows an unusual twisted disc structure, first seen in ground-based photographs taken at the European Southern Observatory in Chile. ESO 510-G13 lies in the southern constellation Hydra, some 150 million light-years from Earth. Details of the galaxy's structure are visible because interstellar dust clouds that trace its disc are silhouetted from behind by light from the galaxy's bright, smooth central bulge.

    The strong warping of the disc indicates that ESO 510-G13 has recently collided with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort galaxies as their stars, gas, and dust merge over millions of years. When the disturbances die out, ESO 510-G13 will be a single galaxy.

    The galaxy's outer regions, especially on the right side of the image, show dark dust and bright clouds of blue stars. This indicates that hot, young stars are forming in the twisted disc. Astronomers believe star formation may be triggered when galaxies collide and their interstellar clouds are compressed.

    The Hubble Heritage Team used WFPC2 to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty

  20. Use of spectral analogy to evaluate canopy reflectance sensitivity to leaf optical property

    NASA Technical Reports Server (NTRS)

    Baret, Frederic; Vanderbilt, Vern C.; Steven, Michael D.; Jacquemoud, Stephane

    1993-01-01

    The spectral variation of canopy reflectance is mostly governed by the absorption properties of the elements, hence the leaves, since their intrinsic scattering properties show very little spectral variation. The relationship between canopy reflectance and leaf reflectance measured at the red edge over sugar beet canopies was used to simulate canopy reflectance from leaf reflectance spectra measured over the whole spectral domain. The results show that the spectral analogies found allows accurate reconstruction of canopy reflectance spectra. Explicit assumptions about the very low spectral variation of leaf intrinsic scattering properties are thus indirectly justified. The sensitivity of canopy reflectance (rho(sub c)) to leaf optical properties can then be investigated from concurrent spectral variations of canopy (delta rho(sub c)/delta lambda) and leaf reflectance (delta rho(sub l)/delta lambda): (delta rho(sub c))/(delta rho(sub l)) = ((delta rho(sub c))/(delta lambda) ((delta rho( sub l))/(delta lambda))(sup -1)). This expression is strictly valid only when the optical properties of the soil background or the other vegetation elements such as bark are either spectrally flat or do not contribute significantly to canopy reflectance. Simulations using the SAIL and PROSPECT models demonstrate that the sensitivity of canopy reflectance to leaf reflectance is significant for large vegetation cover fractions in spectral domains where absorption is low. In these conditions, multiple, scattering enhances the leaf absorption features by a factor that can be greater than 2.0. To override the limitations of the SAIL model for the description of the canopy architecture, we tested the previous findings on experimental data. Concurrent canopy and leaf reflectance spectra were measured for a range of sugar beet canopies. The results show good agreement with the theoretical findings. Conclusions are drawn about the applicability of these findings, with particular attention to

  1. Spectral stratigraphy

    NASA Astrophysics Data System (ADS)

    Lang, Harold R.

    1991-09-01

    Stratigraphic and structural studies of the Wind River and Bighorn basins, Wyoming, and the Guerrero-Morelos basin, Mexico, have resulted in development of ''spectral stratigraphy.'' This approach to stratigraphic analysis uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. This paper reviews selected published examples that illustrate this new stratigraphic procedure. Visible to thermal infrared laboratory, spectral measurements of sedimentary rocks are the physical basis for spectral stratigraphy. Results show that laboratory, field, and remote spectroscopy can augment conventional laboratory and field methods for petrologic analysis, stratigraphic correlation, interpretation of depositional environments, and construction of facies models. Landsat thematic mapper data are used to map strata and construct stratigraphic columns and structural cross sections at 1:24,000 scale or less. Experimental multispectral thermal infrared aircraft data facilitate lithofacies/biofacies analyses. Visible short-wavelength infrared imaging spectrometer data allow remote determination of the stratigraphic distribution of iron oxides, quartz, calcite, dolomite, gypsum, specific clay species, and other minerals diagnostic of environments of deposition. Development of a desk-top, computer-based, geologic analysis system that provides for automated application of these approaches to coregistered digital image and topographic data portends major expansion in the use of spectral stratigraphy for purely scientific (lithospheric research) or practical (resource exploration) objectives.

  2. The Edge, Fall 1999.

    ERIC Educational Resources Information Center

    Edge, 1999

    1999-01-01

    "The Edge" is a Canadian publication for youth. The mandate of the Edge is to support and celebrate all career journeys embraced by youth. This issue contains career profile articles covering three jobs: crane operator, indoor climbing instructor, and product certification tester. Career trends and the state of today's workplace are also…

  3. Supersonic Leading Edge Receptivity

    NASA Technical Reports Server (NTRS)

    Maslov, Anatoly A.

    1998-01-01

    This paper describes experimental studies of leading edge boundary layer receptivity for imposed stream disturbances. Studies were conducted in the supersonic T-325 facility at ITAM and include data for both sharp and blunt leading edges. The data are in agreement with existing theory and should provide guidance for the development of more complete theories and numerical computations of this phenomena.

  4. Changes in spectral properties of detached leaves

    NASA Technical Reports Server (NTRS)

    Daughtry, C. S. T.; Biehl, L. L.

    1984-01-01

    If leaf senescence can be delayed for several days without significant changes in spectral properties, then samples of leaves at remote test sites could be prepared and shipped to laboratories to measure spectral properties. The changes in spectral properties of detached leaves were determined. Leaves from red birch and red pine were immersed in water or 0.001 M benzylaminopurine (BAP) and stored in plastic bags in the dark at either 5 or 25 C. Total directional-hemispherical reflectance and transmittance of the adaxial surface of birch leaves were measured over the 400 to 1100 nm wavelength region with a spectroradiometer and integrating sphere. Pine needles were taped together and reflectance of the mat of needles was measured. Spectral properties changed less than 5% of initial values during the first week when leaves were stored at 5 C. Storage at 25 C promoted rapid senescence and large changes in spectral properties. BAP delayed, but did not stop, senescence at 25 C.

  5. Flap-edge aeroacoustic measurements and predictions

    NASA Astrophysics Data System (ADS)

    Brooks, Thomas F.; Humphreys, William M.

    2003-03-01

    An aeroacoustic model test has been conducted to investigate the mechanisms of sound generation on high-lift wing configurations. This paper presents an analysis of flap side-edge noise, which is often the most dominant source. A model of a main element wing section with a half-span flap was tested at low speeds of up to a Mach number of 0.17, corresponding to a wing chord Reynolds number of approximately 1.7 million. Results are presented for flat (or blunt), flanged, and round flap-edge geometries, with and without boundary-layer tripping, deployed at both moderate and high flap angles. The acoustic database is obtained from a small aperture directional array (SADA) of microphones, which was constructed to electronically steer to different regions of the model and to obtain farfield noise spectra and directivity from these regions. The basic flap-edge aerodynamics is established by static surface pressure data, as well as by computational fluid dynamics (CFD) calculations and simplified edge flow analyses. Distributions of unsteady pressure sensors over the flap allow the noise source regions to be defined and quantified via cross-spectral diagnostics using the SADA output. It is found that shear layer instability and related pressure scatter is the primary noise mechanism. For the flat edge flap, two noise prediction methods based on unsteady-surface-pressure measurements are evaluated and compared to measured noise. One is a new causality spectral approach developed here. The other is a new application of an edge-noise scatter prediction method. The good comparisons for both approaches suggest that the prediction models capture much of the physics. Areas of disagreement appear to reveal when the assumed edge noise mechanism does not fully define the noise production. For the different edge conditions, extensive spectra and directivity are presented. The complexity of the directivity results demonstrate the strong role of edge source geometry and frequency in

  6. The Explorer of Diffuse Galactic Emission (edge)

    NASA Astrophysics Data System (ADS)

    Silverberg, Robert F.; Cheng, Edward S.; Cottingham, David A.; Fixsen, Dale J.; Knox, Lloyd; Meyer, Stephan S.; Timbie, Peter; Wilson, Grant

    Measurements of the large-scale anisotropy of the Cosmic Infared Background (CIB) can be used to determine the characteristics of the distribution of galaxies at the largest spatial scales. With this information important tests of galaxy evolution models and primordial structure growth are possible. In this paper we describe the scientific goals instrumentation and observing strategy of EDGE a mission using an Antarctic Long Duration Balloon (LDB) platform. EDGE will observe the anisotropy in the CIB in 8 spectral bands from 270 GHz-1.5 THz with 6' angular resolution over a region ~400 square degrees. EDGE uses a one-meter class off-axis telescope and an array of Frequency Selective Bololmeters (FSB) to provide the compact and efficient multi- color high sensitivity radiometer required to achieve its scientific objectives.

  7. Effects of Salinity on Leaf Spectral Reflectance and Biochemical Parameters of Nitrogen Fixing Soybean Plants (Glycine max L.)

    NASA Astrophysics Data System (ADS)

    Krezhova, Dora D.; Kirova, Elisaveta B.; Yanev, Tony K.; Iliev, Ilko Ts.

    2010-01-01

    Measurements of physiology and hyperspectral leaf reflectance were used to detect salinity stress in nitrogen fixing soybean plants. Seedlings were inoculated with suspension of Bradyrhizobium japonicum strain 273. Salinity was performed at the stage of 2nd-4th trifoliate expanded leaves by adding of NaCl in the nutrient solution of Helrigel in concentrations 40 mM and 80 mM. A comparative analysis was performed between the changes in the biochemical parameters - stress markers (phenols, proline, malondialdehyde, thiol groups), chlorophyll a and b, hydrogen peroxide, and leaf spectral reflectance in the spectral range 450-850 nm. The spectral measurements were carried out by an USB2000 spectrometer. The reflectance data of the control and treated plants in the red, green, red-edge and the near infrared ranges of the spectrum were subjected to statistical analysis. Statistically significant differences were found through the Student's t-criterion at the two NaCl concentrations in all of the ranges examined with the exception of the near infrared range at 40 mM NaCl concentration. Similar results were obtained through linear discriminant analysis. The tents of the phenols, malondialdehyde and chlorophyll a and b were found to decrease at both salinity treatments. In the spectral data this effect is manifested by decrease of the reflectance values in the green and red ranges. The contents of proline, hydrogen peroxide and thiol groups rose with the NaCl concentration increase. At 80 mM NaCl concentration the values of these markers showed a considerable increase giving evidence that the soybean plants were stressed in comparison with the control. This finding is in agreement with the results from the spectral reflectance analysis.

  8. Reconstruction of Fractional Quantum Hall Edges: Numerical Studies

    NASA Astrophysics Data System (ADS)

    Wan, Xin; Yang, Kun; Rezayi, E. H.

    2003-03-01

    The interplay of electron-electron interaction and confining potential can lead to the reconstruction of fractional quantum Hall edges (Xin Wan, Kun Yang, and E. H. Rezayi, Phys. Rev. Lett. 88, 056802 (2002).). We have performed exact diagonalization studies on microscopic models of fractional quantum Hall liquids, in finite size systems with disc geometry, and found numerical evidence that suggests edge reconstruction occurs under rather general conditions. Due to edge reconstruction, additional nonchiral edge modes can arise for both incompressible and compressible states. We have studied the electron dipole spectral function that is directly related to the microwave conductivity measurement of a two-dimensional electron gas with an array of antidots (P. D. Ye et al., Phys. Rev. B 65, 121305 (2002).). Our results are consistent with the enhanced microwave conductivity observed in experiments at low temperatures, and its suppression at higher temperatures. We also discuss the effects of the edge reconstruction on the fractional quantum Hall edge tunneling experiments.

  9. [Visible-NIR spectral feature of citrus greening disease].

    PubMed

    Li, Xiu-hua; Li, Min-zan; Won Suk, Lee; Reza, Ehsani; Ashish, Ratn Mishra

    2014-06-01

    Citrus greening (Huanglongbing, or HLB) is a devastating disease caused by Candidatus liberibacter which uses psyllids as vectors. It has no cure till now, and poses a huge threat to citrus industry around the world. In order to diagnose, assess and further control this disease, it is of great importance to first find a quick and effective way to detect it. Spectroscopy method, which was widely considered as a fast and nondestructive way, was adopted here to conduct a preliminary exploration of disease characteristics. In order to explore the spectral differences between the healthy and HLB infected leaves and canopies, this study measured the visible-NIR spectral reflectance of their leaves and canopies under lab and field conditions, respectively. The original spectral data were firstly preprocessed with smoothing (or moving average) and cluster average procedures, and then the first derivatives were also calculated to determine the red edge position (REP). In order to solve the multi-peak phenomenon problem, two interpolation methods (three-point Lagrangian interpolation and four-point linear extrapolation) were adopted to calculate the REP for each sample. The results showed that there were, obvious differences at the visible & NIR spectral reflectance between the healthy and HLB infected classes. Comparing with the healthy reflectance, the HLB reflectance was higher at the visible bands because of the yellowish symptoms on the infected leaves, and lower at NIR bands because the disease blocked water transportation to leaves. But the feature at NIR bands was easily affected by environmental factors such as light, background, etc. The REP was also a potential indicator to distinguish those two classes. The average REP was slowly moving toward red bands while the infection level was getting higher. The gap of the average REPs between the healthy and HLB classes reached to a maximum of 20 nm. Even in the dataset with relatively lower variation, the classification

  10. Agile robotic edge finishing

    SciTech Connect

    Powell, M.

    1996-08-01

    Edge finishing processes have seemed like ideal candidates for automation. Most edge finishing processes are unpleasant, dangerous, tedious, expensive, not repeatable and labor intensive. Estimates place the cost of manual edge finishing processes at 12% of the total cost of fabricating precision parts. For small, high precision parts, the cost of hand finishing may be as high as 305 of the total part cost. Up to 50% of this cost could be saved through automation. This cost estimate includes the direct costs of edge finishing: the machining hours required and the 30% scrap and rework rate after manual finishing. Not included in these estimates are the indirect costs resulting from cumulative trauma disorders and retraining costs caused by the high turnover rate for finishing jobs.. Despite the apparent economic advantages, edge finishing has proven difficult to automate except in low precision and/or high volume production environments. Finishing automation systems have not been deployed successfully in Department of Energy defense programs (DOE/DP) production, A few systems have been attempted but have been subsequently abandoned for traditional edge finishing approaches: scraping, grinding, and filing the edges using modified dental tools and hand held power tools. Edge finishing automation has been an elusive but potentially lucrative production enhancement. The amount of time required for reconfiguring workcells for new parts, the time required to reprogram the workcells to finish new parts, and automation equipment to respond to fixturing errors and part tolerances are the most common reasons cited for eliminating automation as an option for DOE/DP edge finishing applications. Existing automated finishing systems have proven to be economically viable only where setup and reprogramming costs are a negligible fraction of overall production costs.

  11. Edge detection: a tutorial review

    SciTech Connect

    Kunt, M.

    1982-01-01

    Major edge detection methods are reviewed from the signal processing and artificial intelligence point of views. In the first class, images are processed first to enhance edges. Then a decision is made to label each picture point as edge or not edge. In the second class edges are viewed as the border-lines of regions whose points share a common property. 21 references.

  12. Flap Edge Aeroacoustic Measurements and Predictions

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Humphreys, William M., Jr.

    2000-01-01

    An aeroacoustic model test has been conducted to investigate the mechanisms of sound generation on high-lift wing configurations. This paper presents an analysis of flap side-edge noise, which is often the most dominant source. A model of a main element wing section with a half-span flap was tested at low speeds of up to a Mach number of 0.17, corresponding to a wing chord Reynolds number of approximately 1.7 million. Results are presented for flat (or blunt), flanged, and round flap-edge geometries, with and without boundary-layer tripping, deployed at both moderate and high flap angles. The acoustic database is obtained from a Small Aperture Directional Array (SADA) of microphones, which was constructed to electronically steer to different regions of the model and to obtain farfield noise spectra and directivity from these regions. The basic flap-edge aerodynamics is established by static surface pressure data, as well as by Computational Fluid Dynamics (CFD) calculations and simplified edge flow analyses. Distributions of unsteady pressure sensors over the flap allow the noise source regions to be defined and quantified via cross-spectral diagnostics using the SADA output. It is found that shear layer instability and related pressure scatter is the primary noise mechanism. For the flat edge flap, two noise prediction methods based on unsteady surface pressure measurements are evaluated and compared to measured noise. One is a new causality spectral approach developed here. The other is a new application of an edge-noise scatter prediction method. The good comparisons for both approaches suggest that much of the physics is captured by the prediction models. Areas of disagreement appear to reveal when the assumed edge noise mechanism does not fully define the noise production. For the different edge conditions, extensive spectra and directivity are presented. Significantly, for each edge configuration, the spectra for different flow speeds, flap angles, and

  13. Flap Edge Aeroacoustic Measurements and Predictions

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Humphreys, William M., Jr.

    2000-01-01

    An aeroacoustic model test has been conducted to investigate the mechanisms of sound generation on high-lift wing configurations. This paper presents an analysis of flap side-edge noise, which is often the most dominant source. A model of a main element wing section with a half-span flap was tested at low speeds of up to a Mach number of 0.17, corresponding to a wing chord Reynolds number of approximately 1.7 million. Results are presented for flat (or blunt), flanged, and round flap-edge geometries, with and without boundary-layer tripping, deployed at both moderate and high flap angles. The acoustic database is obtained from a Small Aperture Directional Array (SADA) of microphones, which was constructed to electronically steer to different regions of the model and to obtain farfield noise spectra and directivity from these regions. The basic flap-edge aerodynamics is established by static surface pressure data, as well as by Computational Fluid Dynamics (CFD) calculations and simplified edge flow analyses. Distributions of unsteady pressure sensors over the flap allow the noise source regions to be defined and quantified via cross-spectral diagnostics using the SADA output. It is found that shear layer instability and related pressure scatter is the primary noise mechanism. For the flat edge flap, two noise prediction methods based on unsteady-surface-pressure measurements are evaluated and compared to measured noise. One is a new causality spectral approach developed here. The other is a new application of an edge-noise scatter prediction method. The good comparisons for both approaches suggest that much of the physics is captured by the prediction models. Areas of disagreement appear to reveal when the assumed edge noise mechanism does not fully define, the noise production. For the different edge conditions, extensive spectra and directivity are presented. Significantly, for each edge configuration, the spectra for different flow speeds, flap angles, and

  14. Polychromator for the edge Thomson scattering system in ITERa)

    NASA Astrophysics Data System (ADS)

    Yatsuka, E.; Hatae, T.; Fujie, D.; Kurokawa, A.; Kusama, Y.

    2012-10-01

    A new type polychromator has been designed for the edge Thomson scattering system in ITER. Signal light is parallelly dispersed into two parts at the first interference filter. Spectral transmissivities for some spectral channels may enhance better than the conventional type polychromator. In the new type polychromator, the misalignment due to the machine accuracy is expected to be within the margin of APD area. In order to calibrate the spectral transmissivity using the dual-laser injection method during the plasma discharge, it is preferred that the spectral channels are separated at the geometric mean of the injected two wavelengths.

  15. Mechanism of Pressure-Induced Phase Transitions, Amorphization, and Absorption-Edge Shift in Photovoltaic Methylammonium Lead Iodide.

    PubMed

    Szafrański, Marek; Katrusiak, Andrzej

    2016-09-01

    Our single-crystal X-ray diffraction study of methylammonium lead triiodide, MAPbI3, provides the first comprehensive structural information on the tetragonal phase II in the pressure range to 0.35 GPa, on the cubic phase IV stable between 0.35 and 2.5 GPa, and on the isostructural cubic phase V observed above 2.5 GPa, which undergoes a gradual amorphization. The optical absorption study confirms that up to 0.35 GPa, the absorption edge of MAPbI3 is red-shifted, allowing an extension of spectral absorption. The transitions to phases IV and V are associated with the abrupt blue shifts of the absorption edge. The strong increase of the energy gap in phase V result in a spectacular color change of the crystal from black to red around 3.5 GPa. The optical changes have been correlated with the pressure-induced strain of the MAPbI3 inorganic framework and its frustration, triggered by methylammonium cations trapped at random orientations in the squeezed voids. PMID:27538989

  16. Spectral Dictionaries

    PubMed Central

    Kim, Sangtae; Gupta, Nitin; Bandeira, Nuno; Pevzner, Pavel A.

    2009-01-01

    Database search tools identify peptides by matching tandem mass spectra against a protein database. We study an alternative approach when all plausible de novo interpretations of a spectrum (spectral dictionary) are generated and then quickly matched against the database. We present a new MS-Dictionary algorithm for efficiently generating spectral dictionaries and demonstrate that MS-Dictionary can identify spectra that are missed in the database search. We argue that MS-Dictionary enables proteogenomics searches in six-frame translation of genomic sequences that may be prohibitively time-consuming for existing database search approaches. We show that such searches allow one to correct sequencing errors and find programmed frameshifts. PMID:18703573

  17. Spectral Predictors

    SciTech Connect

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  18. LOFTrelated semiscale test scene. Water has been dyed red. Hot ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LOFT-related semiscale test scene. Water has been dyed red. Hot steam blowdown exits semiscale at TAN-609 at A&M complex. Edge of building is along left edge of view. Date: 1971. INEEL negative no. 71-376 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  19. Spectral clustering with epidemic diffusion.

    PubMed

    Smith, Laura M; Lerman, Kristina; Garcia-Cardona, Cristina; Percus, Allon G; Ghosh, Rumi

    2013-10-01

    Spectral clustering is widely used to partition graphs into distinct modules or communities. Existing methods for spectral clustering use the eigenvalues and eigenvectors of the graph Laplacian, an operator that is closely associated with random walks on graphs. We propose a spectral partitioning method that exploits the properties of epidemic diffusion. An epidemic is a dynamic process that, unlike the random walk, simultaneously transitions to all the neighbors of a given node. We show that the replicator, an operator describing epidemic diffusion, is equivalent to the symmetric normalized Laplacian of a reweighted graph with edges reweighted by the eigenvector centralities of their incident nodes. Thus, more weight is given to edges connecting more central nodes. We describe a method that partitions the nodes based on the componentwise ratio of the replicator's second eigenvector to the first and compare its performance to traditional spectral clustering techniques on synthetic graphs with known community structure. We demonstrate that the replicator gives preference to dense, clique-like structures, enabling it to more effectively discover communities that may be obscured by dense intercommunity linking. PMID:24229231

  20. Spectral clustering with epidemic diffusion

    NASA Astrophysics Data System (ADS)

    Smith, Laura M.; Lerman, Kristina; Garcia-Cardona, Cristina; Percus, Allon G.; Ghosh, Rumi

    2013-10-01

    Spectral clustering is widely used to partition graphs into distinct modules or communities. Existing methods for spectral clustering use the eigenvalues and eigenvectors of the graph Laplacian, an operator that is closely associated with random walks on graphs. We propose a spectral partitioning method that exploits the properties of epidemic diffusion. An epidemic is a dynamic process that, unlike the random walk, simultaneously transitions to all the neighbors of a given node. We show that the replicator, an operator describing epidemic diffusion, is equivalent to the symmetric normalized Laplacian of a reweighted graph with edges reweighted by the eigenvector centralities of their incident nodes. Thus, more weight is given to edges connecting more central nodes. We describe a method that partitions the nodes based on the componentwise ratio of the replicator's second eigenvector to the first and compare its performance to traditional spectral clustering techniques on synthetic graphs with known community structure. We demonstrate that the replicator gives preference to dense, clique-like structures, enabling it to more effectively discover communities that may be obscured by dense intercommunity linking.

  1. Correlating Species and Spectral Diversity using Remote Sensing in Successional Fields in Virginia

    NASA Astrophysics Data System (ADS)

    Aneece, I.; Epstein, H. E.

    2015-12-01

    Conserving biodiversity can help preserve ecosystem properties and function. As the increasing prevalence of invasive plant species threatens biodiversity, advances in remote sensing technology can help monitor invasive species and their effects on ecosystems and plant communities. To assess whether we could study the effects of invasive species on biodiversity using remote sensing, we asked whether species diversity was positively correlated with spectral diversity, and whether correlations differed among spectral regions along the visible and near-infrared range. To answer these questions, we established community plots in secondary successional fields at the Blandy Experimental Farm in northern Virginia and collected vegetation surveys and ground-level hyperspectral data from 350 to 1025 nm wavelengths. Pearson correlation analysis revealed a positive correlation between spectral diversity and species diversity in the visible ranges of 350-499 nm (Pearson correlation=0.69, p=0.01), 500-589 nm (Pearson=0.64, p=0.03), and 590-674 nm (Pearson=0.70, p=0.01), slight positive correlation in the red edge range of 675-754 nm (Pearson=0.56, p=0.06), and no correlation in the near-infrared ranges of 755-924 nm (Pearson=-0.06, p=0.85) and 925-1025 nm (Pearson=0.30, p=0.34). These differences in correlations across spectral regions may be due to the elements that contribute to signatures in those regions and spectral data transformation methods. To investigate the role of pigment variability in these correlations, we estimated chlorophyll, carotenoid, and anthocyanin concentrations of five dominant species in the plots using vegetation indices. Although interspecific variability in pigment levels exceeded intraspecific variability, chlorophyll (F value=118) was more varied within species than carotenoids (F=322) and anthocyanins (F=126), perhaps contributing to the lack of correlation between species diversity and spectral diversity in the red edge region. Interspecific

  2. The Edge supersonic transport

    NASA Technical Reports Server (NTRS)

    Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian

    1992-01-01

    As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).

  3. Camera Edge Response

    NASA Astrophysics Data System (ADS)

    Zisk, Stanley H.; Wittels, Norman

    1988-02-01

    Edge location is an important machine vision task. Machine vision systems perform mathematical operations on rectangular arrays of numbers that are intended to faithfully represent the spatial distribution of scene luminance. The numbers are produced by periodic sampling and quantization of the camera's video output. This sequence can cause artifacts to appear in the data with a noise spectrum that is high in power at high spatial frequencies. This is a problem because most edge detection algorithms are preferentially sensitive to the high-frequency content in an image. Solid state cameras can introduce errors because of the spatial periodicity of their sensor elements. This can result in problems when image edges are aligned with camera pixel boundaries: (a) some cameras introduce transients into the video signal while switching between sensor elements; (b) most cameras use analog low-pass filters to minimize sampling artifacts and these introduce video phase delays that shift the locations of edges. The problems compound when the vision system samples asynchronously with the camera's pixel rate. Moire patterns (analogous to beat frequencies) can result. In this paper, we examine and model quantization effects in a machine vision system with particular emphasis on edge detection performance. We also compare our models with experimental measurements.

  4. Temperature dependence of the absorption edge of vitreous silica

    NASA Technical Reports Server (NTRS)

    Bates, C. W., Jr.

    1976-01-01

    During an investigation of the optical properties of high-purity vitreous silica (fused quartz), which is being developed by NASA as a reflective and ablative heat shield, some interesting properties of theoretical and experimental nature have become apparent which otherwise may have remained unnoticed. Of particular interest for the NASA application is the shift of the absorption edge toward longer wavelengths with increasing temperature. The results of studies of this shift and of the spectral dependence of the absorption edge are summarized in the present paper. Plots of the absorption edge and the absorption spectrum of fused quartz vs temperature are given and discussed.

  5. Investigate the properties of red QSOs

    NASA Astrophysics Data System (ADS)

    Tsai, An-Li; Hwang, Chrong-Yuan

    2015-08-01

    QSOs are one type of AGNs. The spectral energy distribution of luminous QSOs usually peak at near-UV wavebands and have blue colors. However, recent observations discovered a population of red QSOs. The nature of these red QSOs are still not clear. The redness is obscured either by dusty torus or by dust associated with nuclear star formation. A better wavelength to study the obscuration of QSOs is from IR to radio, which can avoid the dust extinction at optical.We have selected a group of QSOs from the SDSS Quasar Catalog, the VLA FIRST Radio Survey Catalog, and the WISE All Sky Survey Data. We defined the color base on the flux ratio between two bands of continuum emission which avoid strong emission lines. We compare the difference between red QSOs and typical QSOs, and discuss the properties of the red color.

  6. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2016-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  7. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2015-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  8. Leading and trailing edge noise of an airfoil

    NASA Astrophysics Data System (ADS)

    Amiet, R. K.

    Theoretical and experimental predictions of the noise produced when a rigid surface, e.g., an airfoil, with a sharp edge is introduced into a turbulent flow are compared. For an airfoil in rectilinear motion agreement is good. It is better for leading edge than for trailing edge noise because of lack of knowledge of boundary layer surface pressure. For a rotating airfoil, leading edge noise produces spectral peaking around harmonics of blade passage frequency because of multiple eddy chopping. Trailing edge noise produces a broad spectrum. For skewed inflow to a rotor, e.g., a helicopter in forward flight, narrow band tones rapidly degenerate because of the turbulent eddies in the rotor plane. Theory and measurement agree well for helicopters, but not as closely as for airfoils.

  9. Cue combination and color edge detection in natural scenes.

    PubMed

    Zhou, Chunhong; Mel, Bartlett W

    2008-01-01

    Biological vision systems are adept at combining cues to maximize the reliability of object boundary detection, but given a set of co-localized edge detectors operating on different sensory channels, how should their responses be combined to compute overall edge probability? To approach this question, we collected joint responses of red-green and blue-yellow edge detectors both ON- and OFF-edges using a human-labeled image database as ground truth (D. Martin, C. Fowlkes, D. Tal, & J. Malik, 2001). From a Bayesian perspective, the rule for combining edge cues is linear in the individual cue strengths when the ON-edge and OFF-edge joint distributions are (1) statistically independent and (2) lie in an exponential ratio to each other. Neither condition held in the color edge data we collected, and the function P(ON cues)-dubbed the "combination rule"-was correspondingly complex and nonlinear. To characterize the statistical dependencies between edge cues, we developed a generative model ("saturated common factor," SCF) that provided good fits to the measured ON-edge and OFF-edge joint distributions. We also found that a divisive normalization scheme derived from the SCF model transformed raw edge detector responses into values with simpler distributions that satisfied both preconditions for a linear combination rule. A comparison to another normalization scheme (O. Schwartz & E. Simoncelli, 2001) suggests that apparently minor details of the normalization process can strongly influence its performance. Implications of the SCF normalization scheme for cue combination in biological sensory systems are discussed. PMID:18484843

  10. Swords with Blunt Edges

    ERIC Educational Resources Information Center

    Popham, W. James

    2004-01-01

    Many U.S. educators now wonder whether they're teachers or targets. This mentality stems from the specter of their school being sanctioned for failing the state accountability tests mandated under No Child Left Behind (NCLB). According to this author, most of those tests are like blunt-edged swords: They function badly in two directions. While…

  11. Oscillating edge-flames

    NASA Astrophysics Data System (ADS)

    Buckmaster, J.; Zhang, Yi

    1999-09-01

    It has been known for some years that when a near-limit flame spreads over a liquid pool of fuel, the edge of the flame can oscillate. It is also known that when a near-asphyxiated candle-flame burns in zero gravity, the edge of the (hemispherical) flame can oscillate violently prior to extinction. We propose that these oscillations are nothing more than a manifestation of the large Lewis number instability well known in chemical reactor studies and in combustion studies, one that is exacerbated by heat losses. As evidence of this we examine an edge-flame confined within a fuel-supply boundary and an oxygen-supply boundary, anchored by a discontinuity in data at the fuel-supply boundary. We show that when the Lewis number of the fuel is 2, and the Lewis number of the oxidizer is 1, oscillations of the edge occur when the Damköhler number is reduced below a critical value. During a single oscillation period there is a short premixed propagation stage and a long diffusion stage, behaviour that has been observed in flame spread experiments. Oscillations do not occur when both Lewis numbers are equal to 1.

  12. The Inner Urban Edge

    ERIC Educational Resources Information Center

    Ferebee, Ann; Carpenter, Edward K.

    1974-01-01

    In this article, renewal of the inner urban edge is discussed. Norfolk (Virginia) is attempting to blur the difference between old and new neighbor hoods through zoning and architectural controls. Cincinnati (Ohio) is developing an environmentally sound hillside design. Reading (Pennsylvania) is utilizing old railyards for greenbelts of hiking and…

  13. Dramatic Change in Jupiter's Great Red Spot

    NASA Technical Reports Server (NTRS)

    Simon, A. A.; Wong, M. H.; Rogers, J. H.; Orton, G. S.; de Pater, I.; Asay-Davis, X.; Carlson, R. W.; Marcus, P. S.

    2015-01-01

    Jupiter's Great Red Spot (GRS) is one of its most distinct and enduring features, having been continuously observed since the 1800's. It currently spans the smallest latitude and longitude size ever recorded. Here we show analyses of 2014 Hubble spectral imaging data to study the color, structure and internal dynamics of this long-live storm.

  14. Variable Red Giants--The MACHO View

    SciTech Connect

    Keller, S C; Cook, K H

    2003-01-03

    The authors present a study of the MACHO red variable population in the Large Magellanic Cloud. This study reveals six period-luminosity relations among the red variable population. Only two of these were known prior to MACHO. The results are consistent with Mira pulsation in the fundamental mode. A sequence comprising 26% of the red variable population can not be explained by pulsation. They propose a dust {kappa}-mechanism in the circumstellar environment is responsible for the long period variation of these objects. The luminosity function of the variables shows a sharp edge at the tip of the red giant branch (TRGB). This is the first clear indication of a population of variable stars within the immediate vicinity of the TRGB. The results indicate this population amounts to 8% of the RGB population near the TRGB.

  15. Superpixel edges for boundary detection

    DOEpatents

    Moya, Mary M.; Koch, Mark W.

    2016-07-12

    Various embodiments presented herein relate to identifying one or more edges in a synthetic aperture radar (SAR) image comprising a plurality of superpixels. Superpixels sharing an edge (or boundary) can be identified and one or more properties of the shared superpixels can be compared to determine whether the superpixels form the same or two different features. Where the superpixels form the same feature the edge is identified as an internal edge. Where the superpixels form two different features, the edge is identified as an external edge. Based upon classification of the superpixels, the external edge can be further determined to form part of a roof, wall, etc. The superpixels can be formed from a speckle-reduced SAR image product formed from a registered stack of SAR images, which is further segmented into a plurality of superpixels. The edge identification process is applied to the SAR image comprising the superpixels and edges.

  16. Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting

    NASA Technical Reports Server (NTRS)

    Brown, C. S.; Schuerger, A. C.; Sager, J. C.

    1995-01-01

    Light-emitting diodes (LEDs) are a potential irradiation source for intensive plant culture systems and photobiological research. They have small size, low mass, a long functional life, and narrow spectral output. In this study, we measured the growth and dry matter partitioning of 'Hungarian Wax' pepper (Capsicum annuum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation or under broad spectrum metal halide (MH) lamps. Additionally, we describe the thermal and spectral characteristics of these sources. The LEDs used in this study had a narrow bandwidth at half peak height (25 nm) and a focused maximum spectral output at 660 nm for the red and 735 nm for the far-red. Near infrared radiation (800 to 3000 nm) was below detection and thermal infrared radiation (3000 to 50,000 nm) was lower in the LEDs compared to the MH source. Although the red to far-red ratio varied considerably, the calculated phytochrome photostationary state (phi) was only slightly different between the radiation sources. Plant biomass was reduced when peppers were grown under red LEDs in the absence of blue wavelengths compared to plants grown under supplemental blue fluorescent lamps or MH lamps. The addition of far-red radiation resulted in taller plants with greater stem mass than red LEDs alone. There were fewer leaves under red or red plus far-red radiation than with lamps producing blue wavelengths. These results indicate that red LEDs may be suitable, in proper combination with other wavelengths of light, for the culture of plants in tightly controlled environments such as space-based plant culture systems.

  17. Spectroscopic behavior in whispering-gallery modes by edge formation of printed microdisk lasers

    NASA Astrophysics Data System (ADS)

    Chen, Cong; Li, Jifeng; Ryu, Soichiro; Yoshioka, Hiroaki; Ozawa, Masaaki; Oki, Yuji

    2015-12-01

    Dynamic and rapid spectral shifts of whispering-gallery mode (WGM) from microdisk laser were studied. The microdisks with diameter about 100 μm were fabricated by ink-jet printing of Rhodamine 590 doped polymer. Sharper edge microdisk and rounder edge microdisk were pumped with Q-switched Nd:YAG laser(@532 nm). A spectral shift -3.77×10-3 nm/(μJ·mm-2) was occurred in the case of the rounder edge microdisk, which is smaller than the spectral shift -4.21×10-3 nm/(μJ·mm-2) in the case of the sharper edge microdisk. Expecting the anomalous dispersion and Rhodamine 590 degradation affect, under the same excitation condition, the WGM spatial modification can also led to the shifts. And the modification was caused by interaction between the sharpened-edge and the increased optical gain.

  18. Spectral characterization of the LANDSAT Thematic Mapper sensors

    NASA Technical Reports Server (NTRS)

    Markham, B. L.; Barker, J. L.

    1984-01-01

    The spectral coverage characteristics of the two thematic mapper instruments were determined by analyses of spectral measurements of the optics, filters, and detectors. The following results are presented: (1) band 2 and 3 flatness was slightly below specification, and band 7 flatness was below specification; (2) band 5 upper-band edge was higher than specifications; (3) band 2 band edges were shifted upward about 9 nm relative to nominal; and (4) band 4, 5, and 7 lower band edges were 16 to 18 nm higher then nominal.

  19. Laboratory goniometer approach for spectral polarimetric directionality

    NASA Astrophysics Data System (ADS)

    Furey, John; Zahniser, Shellie; Morgan, Cliff

    2016-05-01

    A two meter inner diameter goniometer provides approximately 0.1° angular positioning precision for a series of spectral and polarimetric instruments to enable measurements of the directionality of polarized reflectance from soils in the laboratory, at 10° increments along the azimuth and zenith. Polarimetric imaging instruments to be mounted on the goniometer, with linear polarizers in rotators in front of each instrument, include broadband focal plane array imagers in the Visible band (Vis), Near InfraRed (NIR), Short Wave InfraRed (SWIR), and Long Wave InfraRed (LWIR) spectral bands, as well as a hyperspectral imager in the Vis through NIR. Two additional hyperspectral polarimetric imagers in the Vis through NIR, and SWIR, are to be mounted separately with angles measured by laser on the goniometer frame.

  20. [Research on ground scenery spectral radiation source with tunable spectra].

    PubMed

    Xiang, Jin-rong; Ren, Jian-wei; Li, Bao-yong; Wan, Zhi; Liu, Ze-xun; Liu, Hong-xing; Li, Xian-sheng; Sun, Jing-xu

    2015-02-01

    A spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a ground scenery spectral database was established in the control system. An improved genetic algorithm was proposed, and a large number of ground scenery spectra were produced by the simulator. Spectral similarity and the average spectral matching error of several typical ground scenery spectra were further analyzed. Spectral similarity of red bands, green bands, blue bands and near-infrared spectral band also was discussed. When the radiance of the target was 50 W x (m2 x sr)(-1), the average spectral matching error was less than 10% and spectral similarity was greater than 0.9, up to 0.983. Spectral similarity of red band, green band, blue band and near-infrared band (especially green band and near-infrared band) was less than that of full-band. Compared with blue band and red band, spectral similarity of green band and near-infrared band low-amplitude maximum can rearch 50%. Ground scenery spectrum radiation source can be used as radiometric calibration source for optical remote sensor, and calibration error, which is caused by objectives and calibration sources spectral mismatch, can be effectively reduced. PMID:25970881

  1. Edge detection by nonlinear dynamics

    SciTech Connect

    Wong, Yiu-fai

    1994-07-01

    We demonstrate how the formulation of a nonlinear scale-space filter can be used for edge detection and junction analysis. By casting edge-preserving filtering in terms of maximizing information content subject to an average cost function, the computed cost at each pixel location becomes a local measure of edgeness. This computation depends on a single scale parameter and the given image data. Unlike previous approaches which require careful tuning of the filter kernels for various types of edges, our scheme is general enough to be able to handle different edges, such as lines, step-edges, corners and junctions. Anisotropy in the data is handled automatically by the nonlinear dynamics.

  2. End-to-end sensor simulation for spectral band selection and optimization with application to the Sentinel-2 mission.

    PubMed

    Segl, Karl; Richter, Rudolf; Küster, Theres; Kaufmann, Hermann

    2012-02-01

    An end-to-end sensor simulation is a proper tool for the prediction of the sensor's performance over a range of conditions that cannot be easily measured. In this study, such a tool has been developed that enables the assessment of the optimum spectral resolution configuration of a sensor based on key applications. It employs the spectral molecular absorption and scattering properties of materials that are used for the identification and determination of the abundances of surface and atmospheric constituents and their interdependence on spatial resolution and signal-to-noise ratio as a basis for the detailed design and consolidation of spectral bands for the future Sentinel-2 sensor. The developed tools allow the computation of synthetic Sentinel-2 spectra that form the frame for the subsequent twofold analysis of bands in the atmospheric absorption and window regions. One part of the study comprises the assessment of optimal spatial and spectral resolution configurations for those bands used for atmospheric correction, optimized with regard to the retrieval of aerosols, water vapor, and the detection of cirrus clouds. The second part of the study presents the optimization of thematic bands, mainly driven by the spectral characteristics of vegetation constituents and minerals. The investigation is performed for different wavelength ranges because most remote sensing applications require the use of specific band combinations rather than single bands. The results from the important "red-edge" and the "short-wave infrared" domains are presented. The recommended optimum spectral design predominantly confirms the sensor parameters given by the European Space Agency. The system is capable of retrieving atmospheric and geobiophysical parameters with enhanced quality compared to existing multispectral sensors. Minor spectral changes of single bands are discussed in the context of typical remote sensing applications, supplemented by the recommendation of a few new bands for

  3. Spectral Lines Profiles of Be Star: Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Ahmad, N.; Zainuddin, Mohd. Z. Yahya, Mohd. S.

    2009-08-01

    The variation of spectral lines profiles has been studies on Beta Lyrae based on the data from Jun to Sept. 1999 taken from Ritter Observatory. The V/R between the violet and red intensity peaks of Halpha ratio radial velocity show the violet-shifting and the comparison on spectral profile with data taken in 2007 at Langkawi National Observatory shows some changes.

  4. Oil droplets of bird eyes: microlenses acting as spectral filters

    PubMed Central

    Stavenga, Doekele G.; Wilts, Bodo D.

    2014-01-01

    An important component of the cone photoreceptors of bird eyes is the oil droplets located in front of the visual-pigment-containing outer segments. The droplets vary in colour and are transparent, clear, pale or rather intensely yellow or red owing to various concentrations of carotenoid pigments. Quantitative modelling of the filter characteristics using known carotenoid pigment spectra indicates that the pigments’ absorption spectra are modified by the high concentrations that are present in the yellow and red droplets. The high carotenoid concentrations not only cause strong spectral filtering but also a distinctly increased refractive index at longer wavelengths. The oil droplets therefore act as powerful spherical microlenses, effectively channelling the spectrally filtered light into the photoreceptor's outer segment, possibly thereby compensating for the light loss caused by the spectral filtering. The spectral filtering causes narrow-band photoreceptor spectral sensitivities, which are well suited for spectral discrimination, especially in birds that have feathers coloured by carotenoid pigments. PMID:24395968

  5. Colors of Jupiter's large anticyclones and the interaction of a Tropical Red Oval with the Great Red Spot in 2008

    NASA Astrophysics Data System (ADS)

    Sánchez-Lavega, A.; Legarreta, J.; García-Melendo, E.; Hueso, R.; Pérez-Hoyos, S.; Gómez-Forrellad, J. M.; Fletcher, L. N.; Orton, G. S.; Simon-Miller, A.; Chanover, N.; Irwin, P.; Tanga, P.; Cecconi, M.

    2013-12-01

    nature and mechanisms producing the chromophore agents that provide color to the upper clouds and hazes of the atmospheres of the giant planets are largely unknown. In recent times, the changes in red coloration that have occurred in large- and medium-scale Jovian anticyclones have been particularly interesting. In late June and early July 2008, a particularly color intense tropical red oval interacted with the Great Red Spot (GRS) leading to the destruction of the tropical red oval and cloud dispersion. We present a detailed study of the tropical vortices, usually white but sometimes red, and a characterization of their color spectral signatures and dynamics. From the spectral reflectivity in methane bands we study their vertical cloud structure compared to that of the GRS and BA. Using two spectral indices we found a near correlation between anticyclones cloud top altitudes and red color. We present detailed observations of the interaction of the red oval with the GRS and model simulations of the phenomena that allow us to constrain the relative vertical extent of the vortices. We conclude that the vertical cloud structure, vertical extent, and dynamics of Jovian anticyclones are not the causes of their coloration. We propose that the red chromophore forms when background material (a compound or particles) is entrained by the vortex, transforming into red once inside the vortex due to internal conditions, exposure to ultraviolet radiation, or to the mixing of two chemical compounds that react inside the vortex, confined by a potential vorticity ring barrier.

  6. Spectral monitoring of moorland plant phenology to identify a temporal window for hyperspectral remote sensing of peatland

    NASA Astrophysics Data System (ADS)

    Cole, Beth; McMorrow, Julia; Evans, Martin

    2014-04-01

    Recognising the importance of the timing of image acquisition on the spectral response in remote sensing of vegetated ecosystems is essential. This study used full wavelength, 350-2500 nm, field spectroscopy to establish a spectral library of phenological change for key moorland species, and to investigate suitable temporal windows for monitoring upland peatland systems. Spectral responses over two consecutive growing seasons were recorded at single species plots for key moorland species and species sown to restore eroding peat. This was related to phenological change using narrowband vegetation indices (Red Edge Position, Photochemical Reflectance Index, Plant Senescence Reflection Index and Cellulose Absorption Index); that capture green-up and senescence related changes in absorption features in the visible to near infrared and the shortwave infrared. The selection of indices was confirmed by identifying the regions of maximum variation in the captured reflectance across the full spectrum. The indices show change in the degree of variation between species occurring from April to September, measured for plant functional types. A discriminant function analysis between indices and plant functional types determines how well each index was able to differentiate between the plant functional groups for each month. It identifies April and July as the two months where the species are most separable. What is presented here is not one single recommendation for the optimal temporal window for operational monitoring, but a fuller understanding of how the spectral response changes with the phenological cycle, including recommendations for what indices are important throughout the year.

  7. Spectral discrimination of giant reed (Arundo donax L.): A seasonal study in riparian areas

    NASA Astrophysics Data System (ADS)

    Fernandes, Maria Rosário; Aguiar, Francisca C.; Silva, João M. N.; Ferreira, Maria Teresa; Pereira, José M. C.

    2013-06-01

    The giant reed (Arundo donax L.) is amongst the one hundred worst invasive alien species of the world, and it is responsible for biodiversity loss and failure of ecosystem functions in riparian habitats. In this work, field spectroradiometry was used to assess the spectral separability of the giant reed from the adjacent vegetation and from the common reed, a native similar species. The study was conducted at different phenological periods and also for the giant reed stands regenerated after mechanical cutting (giant reed_RAC). A hierarchical procedure using Kruskal-Wallis test followed by Classification and Regression Trees (CART) was used to select the minimum number of optimal bands that discriminate the giant reed from the adjacent vegetation. A new approach was used to identify sets of wavelengths - wavezones - that maximize the spectral separability beyond the minimum number of optimal bands. Jeffries Matusita and Bhattacharya distance were used to evaluate the spectral separability using the minimum optimal bands and in three simulated satellite images, namely Landsat, IKONOS and SPOT. Giant reed was spectrally separable from the adjacent vegetation, both at the vegetative and the senescent period, exception made to the common reed at the vegetative period. The red edge region was repeatedly selected, although the visible region was also important to separate the giant reed from the herbaceous vegetation and the mid infrared region to the discrimination from the woody vegetation. The highest separability was obtained for the giant reed_RAC stands, due to its highly homogeneous, dense and dark-green stands. Results are discussed by relating the phenological, morphological and structural features of the giant reed stands and the adjacent vegetation with their optical traits. Weaknesses and strengths of the giant reed spectral discrimination are highlighted and implications of imagery selection for mapping purposes are argued based on present results.

  8. Spectral separation of Cr3+ optical centers in stoichiometric magnesium-doped lithium niobate crystals

    NASA Astrophysics Data System (ADS)

    Galutskii, V. V.; Stroganova, E. V.; Yakovenko, N. A.

    2011-03-01

    The broadband luminescence of chromium optical centers with strongly overlapping spectral lines and similar emission probabilities from excited 4 T 2 states of red and green Cr3+ centers in stoichiometric magnesium-doped lithium niobate crystals has been separated for the first time. The spectral-luminescence characteristics and parameters of intracenter interaction between red and green optical Cr3+ centers in stoichiometric lithium niobate have been calculated. The luminescence quantum efficiencies of red and green chromium centers are determined.

  9. Competing edge networks

    NASA Astrophysics Data System (ADS)

    Parsons, Mark; Grindrod, Peter

    2012-06-01

    We introduce a model for a pair of nonlinear evolving networks, defined over a common set of vertices, subject to edgewise competition. Each network may grow new edges spontaneously or through triad closure. Both networks inhibit the other's growth and encourage the other's demise. These nonlinear stochastic competition equations yield to a mean field analysis resulting in a nonlinear deterministic system. There may be multiple equilibria; and bifurcations of different types are shown to occur within a reduced parameter space. This situation models competitive communication networks such as BlackBerry Messenger displacing SMS; or instant messaging displacing emails.

  10. The cutting edge.

    PubMed

    Hagland, M; Lumsdon, K; Montague, J; Serb, C

    1995-08-01

    With managed care payment becoming the norm, employers actively pursuing keener benefits management, health care markets evolving at warp speed, and clinical and information technologies spawning new capabilities every day, the cutting edge in health care keeps slicing ever-deeper. With that in mind, we at Hospitals & Health Networks have developed a browser's compendium of some of the leading people, places (organizations and programs) and technologies that are helping move the field forward into the next stage. Each entry is unique; what they all share is an innovative quality that others will emulate. PMID:7627230