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Sample records for infrared contrast ratio

  1. Improving the Visible and Infrared Contrast Ratio of Microshutter Arrays

    NASA Technical Reports Server (NTRS)

    Jhabvala, Murzy; Li, Mary; Moseley, Harvey; Franz, Dave; Yun, Zheng; Kutyrev, Alexander

    2009-01-01

    Three device improvements have been developed that dramatically enhance the contrast ratio of microshutters. The goal of a microshutter is to allow as much light through as possible when the shutters are in the open configuration, and preventing any light from passing through when they are in the closed position. The ratio of the transmitted light that is blocked is defined here as the contrast ratio. Three major components contribute to the improved performance of these microshutters: 1. The precise implementation of light shields, which protect the gap around the shutters so no light can leak through. It has been ascertained that without the light shield there would be a gap on the order of 1 percent of the shutter area, limiting the contrast to a maximum of 100. 2. The precise coating of the interior wall of each microshutter was improved with an insulator and metal using an angle deposition technique. The coating prevents any infrared light that finds an entrance on the surface of the microshutter cell from being emitted from a sidewall. Since silicon is in effect transparent to any light with a wavelength longer than .1 micrometer, these coatings are essential to blocking any stray signals when the shutters are closed. 3. A thin film of molybdenum nitride (MoN) was integrated onto the surface of the microshutter blade. This film provides the majority of light blockage over the microshutter and also ensures that the shutter can be operated over a wide temperature range by maintaining its flatness. These improvements were motivated by the requirements dictated by the James Webb Space Telescope NIRSpec instrument. The science goals of the NIRSpec require observing some of the very faintest objects in a given field of view that also may contain some very bright objects. To observe the faint objects, the light from the bright objects - which could be thousands of times brighter - must be completely blocked. If a closed microshutter is even slightly transmissive, a

  2. Flash Infrared Thermography Contrast Data Analysis Technique

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay

    2014-01-01

    This paper provides information on an IR Contrast technique that involves extracting normalized contrast versus time evolutions from the flash thermography inspection infrared video data. The analysis calculates thermal measurement features from the contrast evolution. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat-bottom holes in the subject material. The measurement features and the contrast simulation are used to evaluate flash thermography data in order to characterize delamination-like anomalies. The thermal measurement features relate to the anomaly characteristics. The contrast evolution simulation is matched to the measured contrast evolution over an anomaly to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat-bottom hole (EFBH) similar to that used as input to the simulation. A similar analysis, in terms of diameter and depth of an equivalent uniform gap (EUG) providing a best match with the measured contrast evolution, is also provided. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH/EUG diameter are compared to evaluate the anomaly. The information provided here is geared towards explaining the IR Contrast technique. Results from a limited amount of validation data on reinforced carbon-carbon (RCC) hardware are included in this paper.

  3. In vivo imaging with near-infrared fluorescence lifetime contrast

    NASA Astrophysics Data System (ADS)

    Akers, Walter J.; Berezin, Mikhail Y.; Lee, Hyeran; Achilefu, Samuel

    2009-02-01

    Fluorescence imaging is a mainstay of biomedical research, allowing detection of molecular events in both fixed and living cells, tissues and whole animals. Such high resolution fluorescence imaging is hampered by unwanted signal from intrinsic background fluorescence and scattered light. The signal to background ratio can be improved by using extrinsic contrast agents and greatly enhanced by multispectral imaging methods. Unfortunately, these methods are insufficient for deep tissue imaging where high contrast and speedy acquisition are necessary. Fluorescence lifetime (FLT) is an inherent characteristic of each fluorescent species that can be independent of intensity and spectral properties. Accordingly, FLT-based detection provides an additional contrast mechanism to optical measurements. This contrast is particularly important in the near-infrared (NIR) due to relative transparency of tissue as well as the broad absorption and emission spectra of dyes that are active in this region. Here we report comparative analysis of signal distribution of several NIR fluorescent polymethine dyes in living mice and their correlations with lifetimes obtained in vitro using solution models. The FLT data obtained from dyes dissolved in serum albumin solution correlated well with FLTs measured in vivo. Thus the albumin solution model could be used as a good predictive model for in vivo FLT behavior of newly developed fluorescent reporters. Subsequent experiments in vivo, including monitoring slow release kinetics and detecting proteinuria, demonstrate the complementary nature of FLT for fluorescence intensity imaging.

  4. An adaptive algorithm for low contrast infrared image enhancement

    NASA Astrophysics Data System (ADS)

    Liu, Sheng-dong; Peng, Cheng-yuan; Wang, Ming-jia; Wu, Zhi-guo; Liu, Jia-qi

    2013-08-01

    An adaptive infrared image enhancement algorithm for low contrast is proposed in this paper, to deal with the problem that conventional image enhancement algorithm is not able to effective identify the interesting region when dynamic range is large in image. This algorithm begin with the human visual perception characteristics, take account of the global adaptive image enhancement and local feature boost, not only the contrast of image is raised, but also the texture of picture is more distinct. Firstly, the global image dynamic range is adjusted from the overall, the dynamic range of original image and display grayscale form corresponding relationship, the gray scale of bright object is raised and the the gray scale of dark target is reduced at the same time, to improve the overall image contrast. Secondly, the corresponding filtering algorithm is used on the current point and its neighborhood pixels to extract image texture information, to adjust the brightness of the current point in order to enhance the local contrast of the image. The algorithm overcomes the default that the outline is easy to vague in traditional edge detection algorithm, and ensure the distinctness of texture detail in image enhancement. Lastly, we normalize the global luminance adjustment image and the local brightness adjustment image, to ensure a smooth transition of image details. A lot of experiments is made to compare the algorithm proposed in this paper with other convention image enhancement algorithm, and two groups of vague IR image are taken in experiment. Experiments show that: the contrast ratio of the picture is boosted after handled by histogram equalization algorithm, but the detail of the picture is not clear, the detail of the picture can be distinguished after handled by the Retinex algorithm. The image after deal with by self-adaptive enhancement algorithm proposed in this paper becomes clear in details, and the image contrast is markedly improved in compared with Retinex

  5. Multiphoton microscopy with near infrared contrast agents

    NASA Astrophysics Data System (ADS)

    Yazdanfar, Siavash; Joo, Chulmin; Zhan, Chun; Berezin, Mikhail Y.; Akers, Walter J.; Achilefu, Samuel

    2010-05-01

    While multiphoton microscopy (MPM) has been performed with a wide range of excitation wavelengths, fluorescence emission has been limited to the visible spectrum. We introduce a paradigm for MPM of near-infrared (NIR) fluorescent molecular probes via nonlinear excitation at 1550 nm. This all-NIR system expands the range of available MPM fluorophores, virtually eliminates background autofluorescence, and allows for use of fiber-based, turnkey ultrafast lasers developed for telecommunications.

  6. Infrared contrast of crude-oil-covered water surfaces.

    PubMed

    Shih, Wei-Chuan; Andrews, A Ballard

    2008-12-15

    Infrared oil spill detection utilizes either temperature or emissivity contrast of native and oil-covered water surfaces. In particular, the thickness dependent radiance contrast due to thin film interference has been studied. Together with detection boundaries derived from the radiative transfer equation, we can explain historically observed daytime contrast reversal and our observations during nighttime, better contrast from thin oil slicks than from thick films, which to our knowledge has not been mentioned in the literature. These findings have important implications to long-wavelength infrared (LWIR) instrument design and data interpretation for crude oil spill detection. PMID:19079527

  7. Infrared Contrast Analysis Technique for Flash Thermography Nondestructive Evaluation

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay

    2014-01-01

    The paper deals with the infrared flash thermography inspection to detect and analyze delamination-like anomalies in nonmetallic materials. It provides information on an IR Contrast technique that involves extracting normalized contrast verses time evolutions from the flash thermography infrared video data. The paper provides the analytical model used in the simulation of infrared image contrast. The contrast evolution simulation is achieved through calibration on measured contrast evolutions from many flat bottom holes in the subject material. The paper also provides formulas to calculate values of the thermal measurement features from the measured contrast evolution curve. Many thermal measurement features of the contrast evolution that relate to the anomaly characteristics are calculated. The measurement features and the contrast simulation are used to evaluate flash thermography inspection data in order to characterize the delamination-like anomalies. In addition, the contrast evolution prediction is matched to the measured anomaly contrast evolution to provide an assessment of the anomaly depth and width in terms of depth and diameter of the corresponding equivalent flat-bottom hole (EFBH) or equivalent uniform gap (EUG). The paper provides anomaly edge detection technique called the half-max technique which is also used to estimate width of an indication. The EFBH/EUG and half-max width estimations are used to assess anomaly size. The paper also provides some information on the "IR Contrast" software application, half-max technique and IR Contrast feature imaging application, which are based on models provided in this paper.

  8. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner.

    PubMed

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed. PMID:26724040

  9. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    SciTech Connect

    Müller, Mark Yaroshenko, Andre; Velroyen, Astrid; Tapfer, Arne; Bech, Martin; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-15

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

  10. Contrast-to-noise ratio optimization for a prototype phase-contrast computed tomography scanner

    NASA Astrophysics Data System (ADS)

    Müller, Mark; Yaroshenko, Andre; Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Pauwels, Bart; Bruyndonckx, Peter; Sasov, Alexander; Pfeiffer, Franz

    2015-12-01

    In the field of biomedical X-ray imaging, novel techniques, such as phase-contrast and dark-field imaging, have the potential to enhance the contrast and provide complementary structural information about a specimen. In this paper, a first prototype of a preclinical X-ray phase-contrast CT scanner based on a Talbot-Lau interferometer is characterized. We present a study of the contrast-to-noise ratios for attenuation and phase-contrast images acquired with the prototype scanner. The shown results are based on a series of projection images and tomographic data sets of a plastic phantom in phase and attenuation-contrast recorded with varying acquisition settings. Subsequently, the signal and noise distribution of different regions in the phantom were determined. We present a novel method for estimation of contrast-to-noise ratios for projection images based on the cylindrical geometry of the phantom. Analytical functions, representing the expected signal in phase and attenuation-contrast for a circular object, are fitted to individual line profiles of the projection data. The free parameter of the fit function is used to estimate the contrast and the goodness of the fit is determined to assess the noise in the respective signal. The results depict the dependence of the contrast-to-noise ratios on the applied source voltages, the number of steps of the phase stepping routine, and the exposure times for an individual step. Moreover, the influence of the number of projection angles on the image quality of CT slices is investigated. Finally, the implications for future imaging purposes with the scanner are discussed.

  11. Enhancement of multispectral thermal infrared images - Decorrelation contrast stretching

    NASA Technical Reports Server (NTRS)

    Gillespie, Alan R.

    1992-01-01

    Decorrelation contrast stretching is an effective method for displaying information from multispectral thermal infrared (TIR) images. The technique involves transformation of the data to principle components ('decorrelation'), independent contrast 'stretching' of data from the new 'decorrelated' image bands, and retransformation of the stretched data back to the approximate original axes, based on the inverse of the principle component rotation. The enhancement is robust in that colors of the same scene components are similar in enhanced images of similar scenes, or the same scene imaged at different times. Decorrelation contrast stretching is reviewed in the context of other enhancements applied to TIR images.

  12. Limitations of contrast enhancement for infrared target identification

    NASA Astrophysics Data System (ADS)

    Du Bosq, Todd W.; Fanning, Jonathan D.

    2009-05-01

    Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content. Automatic contrast enhancement techniques do not always achieve this improvement. In some cases, the contrast can increase to a level of target saturation. This paper assesses the range-performance effects of contrast enhancement for target identification as a function of image saturation. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing contrast enhancement processed images at various levels of saturation. Contrast enhancement is modeled in the U.S. Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of specific feature saturation or enhancement. The measured results follow the predicted performance based on the target task difficulty metric used in NVThermIP for the non-saturated cases. The saturated images reduce the information contained in the target and performance suffers. The model treats the contrast of the target as uniform over spatial frequency. As the contrast is enhanced, the model assumes that the contrast is enhanced uniformly over the spatial frequencies. After saturation, the spatial cues that differentiate one tank from another are located in a limited band of spatial frequencies. A frequency dependent treatment of target contrast is needed to predict performance of over-processed images.

  13. Visible and infrared polarization ratio spectroreflectometer

    NASA Technical Reports Server (NTRS)

    Batten, C. E. (Inventor)

    1980-01-01

    The instrument assists in determining the refractive index and absorption index, at different spectral frequencies, of a solid sample by illuminating the sample at various angles in incidence and measuring the corresponding reflected intensities at various spectral frequencies and polarization angles. The ratio of the intensity of the reflected light for parallel polarized light to that for perpendicular polarized light at two different angles of incidence can be used to determine the optical constants of the sample. The invention involves an apparatus for facilitating the utilization of a wide variety of angles of incidence. The light source and polarizing element are positioned on an outer platform; the sample is positioned on an inner platform. The two platforms rotate about a common axis and cooperate in their rotation such that the sample is rotated one degree for every two degrees of rotation of the light source. This maintains the impingement of the reflected light upon the detector for any angle of incidence without moving or adjusting the detector which allows a continuous change in the angle of incidence.

  14. Measuring and Estimating Normalized Contrast in Infrared Flash Thermography

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay M.

    2013-01-01

    Infrared flash thermography (IRFT) is used to detect void-like flaws in a test object. The IRFT technique involves heating up the part surface using a flash of flash lamps. The post-flash evolution of the part surface temperature is sensed by an IR camera in terms of pixel intensity of image pixels. The IR technique involves recording of the IR video image data and analysis of the data using the normalized pixel intensity and temperature contrast analysis method for characterization of void-like flaws for depth and width. This work introduces a new definition of the normalized IR pixel intensity contrast and normalized surface temperature contrast. A procedure is provided to compute the pixel intensity contrast from the camera pixel intensity evolution data. The pixel intensity contrast and the corresponding surface temperature contrast differ but are related. This work provides a method to estimate the temperature evolution and the normalized temperature contrast from the measured pixel intensity evolution data and some additional measurements during data acquisition.

  15. High ratio long-wave infrared continuous zoom system

    NASA Astrophysics Data System (ADS)

    Yan, Jing; Sun, Quan; Liu, Ying; Zhou, Hao; Huan, Kewei; Shi, Xiao-guang

    2013-09-01

    As infrared zoom systems change the focal length continuously, remain images stability and keep good image quality during the process of zoom, it is widely applied to infrared navigation, infrared detection, infrared-guided etc vehicular and airborne area. In order to satisfy the growing demand of infrared continuous zoom system, a zoom ratio of ten times long-wave infrared continuous zoom optical system that based on an uncooled detector was designed. System guided by the zoom theory of positive groups of compensation, calculated the initial structure of the system and according to the system of optical parameters with using ZEMAX software for optical design did an aberration balance and optimized, then the optical system image quality was systematically analyzed and evaluated. The result showed that the modulation transfer function (MTF) was above 0.4 within the whole focal range at spatial frequency 16 lp/mm, the root mean square radius of maximum dispersion spot was smaller than a pixel dimension and it met the requirements of the system imaging quality when F/# was 2, continuous zoom range was from 40 mm to 400 mm and the image size was 12 mm. The design of the system realized the requirements of compact structure, large zoom ratio, easily assembled and excellent image quality to optical system for infrared imaging.

  16. Infrared contrast data analysis method for quantitative measurement and monitoring in flash infrared thermography

    NASA Astrophysics Data System (ADS)

    Koshti, Ajay M.

    2015-04-01

    The paper provides information on a new infrared (IR) image contrast data post-processing method that involves converting raw data to normalized contrast versus time evolutions from the flash infrared thermography inspection video data. Thermal measurement features such as peak contrast, peak contrast time, persistence time, and persistence energy are calculated from the contrast evolutions. In addition, simulation of the contrast evolution is achieved through calibration on measured contrast evolutions from many flat bottom holes in a test plate of the subject material. The measurement features are used to monitor growth of anomalies and to characterize the void-like anomalies. The method was developed to monitor and analyze void-like anomalies in reinforced carbon-carbon (RCC) materials used on the wing leading edge of the NASA Space Shuttle Orbiters, but the method is equally applicable to other materials. The thermal measurement features relate to the anomaly characteristics such as depth and size. Calibration of the contrast is used to provide an assessment of the anomaly depth and width which correspond to the depth and diameter of the equivalent flat bottom hole (EFBH) from the calibration data. An edge detection technique called the half-max is used to measure width and length of the anomaly. Results of the half-max width and the EFBH diameter are compared with actual widths to evaluate utility of IR Contrast method. Some thermal measurements relate to gap thickness of the delaminations. Results of IR Contrast method on RCC hardware are provided. Keywords: normalized contrast, flash infrared thermography.

  17. Color contrast enhancement method of infrared polarization fused image

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Xie, Chen

    2015-10-01

    As the traditional color fusion method based on color transfer algorithm has an issue that the color of target and background is similar. A kind of infrared polarization image color fusion method based on color contrast enhancement was proposed. Firstly the infrared radiation intensity image and the polarization image were color fused, and then color transfer technology was used between color reference image and initial fused image in the YCbCr color space. Secondly Otsu segmentation method was used to extract the target area image from infrared polarization image. Lastly the H,S,I component of the color fusion image which obtained by color transfer was adjusted to obtain the final fused image by using target area in the HSI space. Experimental results show that, the fused result which obtained by the proposed method is rich in detail and makes the contrast of target and background more outstanding. And then the ability of target detection and identification can be improved by the method.

  18. Quantitative analysis of contrast to noise ratio using a phase contrast x-ray imaging prototype

    NASA Astrophysics Data System (ADS)

    Ghani, Muhammad U.; Wu, Di; Li, Yuhua; Kang, Minhua; Chen, Wei R.; Wu, Xizeng; Liu, Hong

    2013-02-01

    The purpose of this study was to determine the Contrast to Noise Ratio (CNR) of the x-ray images taken with the phase contrast imaging mode and compare them with the CNR of the images taken under the conventional mode. For each mode, three images were taken under three exposure conditions of 100 kVp (2.8mAs), 120 kVp (1.9mAs) and 140kVp (1.42mAs). A 1.61cm thick contrast detail phantom was used as an imaging object. For phase contrast, the source to image detector distance (SID) was 182.88 cm and the source to object (SOD) distance was 73.15 cm. The SOD was the same as SID in the conventional imaging mode. A computed radiography (CR) plate was used as a detector and the output CR images were converted to linear form in relation with the incident x-ray exposure. To calculate CNR, an image processing software was used to determine the mean pixel value and the standard deviation of the pixels in the region of interest (ROI) and in the nearby background around ROI. At any given exposure condition investigated in this study, the CNR values for the phase contrast images were better as compared to the corresponding conventional mode images. The superior image quality in terms of CNR is contributed by the phase-shifts resulted contrast, as well as the reduced scatters due to the air gap between the object and the detector.

  19. Contrast to Noise Ratio and Contrast Detail Analysis in Mammography:A Monte Carlo Study

    NASA Astrophysics Data System (ADS)

    Metaxas, V.; Delis, H.; Kalogeropoulou, C.; Zampakis, P.; Panayiotakis, G.

    2015-09-01

    The mammographic spectrum is one of the major factors affecting image quality in mammography. In this study, a Monte Carlo (MC) simulation model was used to evaluate image quality characteristics of various mammographic spectra. The anode/filter combinations evaluated, were those traditionally used in mammography, for tube voltages between 26 and 30 kVp. The imaging performance was investigated in terms of Contrast to Noise Ratio (CNR) and Contrast Detail (CD) analysis, by involving human observers, utilizing a mathematical CD phantom. Soft spectra provided the best characteristics in terms of both CNR and CD scores, while tube voltage had a limited effect. W-anode spectra filtered with k-edge filters demonstrated an improved performance, that sometimes was better compared to softer x-ray spectra, produced by Mo or Rh anode. Regarding the filter material, k-edge filters showed superior performance compared to Al filters.

  20. Polarization enhancement of contrast in infrared ship/background imaging

    NASA Astrophysics Data System (ADS)

    Cooper, A. W.; Lentz, W. J.; Walker, P. L.; Chan, P. M.

    1995-02-01

    During the MAPTIP (Marine Aerosol Properties and Thermal Imager Performance) experiment series in Dutch coastal waters in October 1993 shore-based polarized infrared images were recorded of air (fixed wing and helicopter) and sea targets in sea and air backgrounds, including a number of vertically and horizontally polarized image pairs of the Dutch oceanographic research vessel Hr Ms Tydeman. Complete characterization of the environmental conditions in the measurement area will be available through other MAPTIP participants. These images show no significant polarization features in ship images (less than 5%) or in sky background, but a considerable degree of vertical ('p') polarization in the sea background radiance at low emission (near grazing) angles, which is ascribed to surface emission polarization. This phenomenon for all observed times of day and sun positions, and more strongly in the LWIR than in the MWIR. A horizontal polarization filter provided 10 to 20% ship-to-sea contrast improvement due to suppression of sea background, and enhances horizon sea/sky contrast by up to 15%. These results are consistent with our previous measurements of polarization in the sun glint channel.

  1. Infrared Supernova Remnants and their Infrared-to-X-ray Flux Ratios

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul; Lee, Jae-Joon; Jeong, Il-Gyo; Seok, Ji Yeon; Kim, Hyun-Jeong

    2016-04-01

    Recent high-resolution infrared space missions have revealed supernova remnants (SNRs) of diverse morphology in infrared (IR) dust emission that are often very different from their X-ray appearance. The observed range of infrared-to-X-ray (IRX) flux ratios of SNRs is also wide. For a sample of 20 Galactic SNRs, we obtain their IR and X-ray properties and investigate the physical causes for such large differences. We find that the observed IRX flux ratios ({R}{{IRX,obs}}) are related to the IRX morphology, with SNRs with the largest {R}{{IRX,obs}} showing anticorrelated IRX morphology. By analyzing the relation of {R}{{IRX,obs}} to X-ray and IR parameters, we show that the {R}{{IRX,obs}} of some SNRs agrees with theoretical ratios of SNR shocks in which dust grains are heated and destroyed by collisions with plasma particles. For the majority of SNRs, however, {R}{{IRX,obs}} values are either significantly smaller or significantly larger than the theoretical ratios. The latter SNRs have relatively low dust temperatures. We discuss how the natural and/or environmental properties of SNRs could have affected the IRX flux ratios and the IRX morphology of these SNRs. We conclude that the SNRs with largest {R}{{IRX,obs}} are probably located in a dense environment and that their IR emission is from dust heated by shock radiation rather than by collisions. Our result suggests that the IRX flux ratio, together with dust temperature, can be used to infer the nature of unresolved SNRs in external galaxies.

  2. Infrared moving point target detection based on spatial-temporal local contrast filter

    NASA Astrophysics Data System (ADS)

    Deng, Lizhen; Zhu, Hu; Tao, Chao; Wei, Yantao

    2016-05-01

    Infrared moving point target detection is a challenging task. In this paper, we define a novel spatial local contrast (SLC) and a novel temporal local contrast (TLC) to enhance the target's contrast. Based on the defined spatial local contrast and temporal local contrast, we propose a simple but powerful spatial-temporal local contrast filter (STLCF) to detect moving point target from infrared image sequences. In order to verify the performance of spatial-temporal local contrast filter on detecting moving point target, different detection methods are used to detect the target from several infrared image sequences for comparison. The experimental results show that the proposed spatial-temporal local contrast filter has great superiority in moving point target detection.

  3. Tailored Near-Infrared Contrast Agents for Image Guided Surgery

    PubMed Central

    Njiojob, Costyl N.; Owens, Eric A.; Narayana, Lakshminarayana; Hyun, Hoon; Choi, Hak Soo; Henary, Maged

    2015-01-01

    The success of near-infrared (NIR) fluorescence to be employed for intraoperative imaging relies on the ability to develop a highly stable, NIR fluorescent, nontoxic, biocompatible, and highly excreted compound that retains a reactive functionality for conjugation to a cancer-recognizing peptide. Herein, systematic modifications to previously detailed fluorophore ZW800-1 are explored. Specific modifications, including the isosteric replacement of the O atom of ZW800-1, include nucleophilic amine and sulfur species attached to the heptamethine core. These novel compounds have shown similar satisfactory results in biodistribution and clearance while also expressing increased stability in serum. Most importantly, all of the synthesized and evaluated compounds display a reactive functionality (either a free amino group or carboxylic acid moiety) for further bioconjugation. The results obtained from the newly prepared derivatives demonstrate that the central substitution with the studied linking agents retains the ultralow background in vivo performance of the fluorophores regardless of the total net charge. PMID:25711712

  4. 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

  5. Large infrared absorptance of bimaterial microcantilevers based on silicon high contrast grating

    NASA Astrophysics Data System (ADS)

    Kwon, Beomjin; Seong, Myunghoon; Liu, Jui-Nung; Rosenberger, Matthew R.; Schulmerich, Matthew V.; Bhargava, Rohit; Cunningham, Brian T.; King, William P.

    2013-10-01

    Manufacturing sensors for the mid-IR spectral region (3-11 μm) are especially challenging given the large spectral bandwidth, lack of convenient material properties, and need for sensitivity due to weak sources. Here, we present bimaterial microcantilevers based on silicon high contrast grating (HCG) as alternatives. The grating integrated into the cantilevers leverages the high refractive index contrast between the silicon and its surrounding medium, air. The cantilevers with HCG exhibit larger active spectral range and absorptance in mid-IR as compared to cantilevers without HCG. We design and fabricate two types of HCG bimaterial cantilevers such that the HCG resonance modes occur in mid-IR spectral region. Based on the measurements using a Fourier transform infrared (FTIR) microspectrometer, we show that the HCG cantilevers have 3-4X wider total IR absorptance bandwidths and 30% larger absorptance peak amplitude than the cantilever without HCG, over the 3-11 μm wavelength region. Based on the enhanced IR absorptance, HCG cantilevers show 13-47X greater responsivity than the cantilever without HCG. Finally, we demonstrate that the enhanced IR sensitivity of the HCG cantilever enables transmission IR spectroscopy with a Michelson interferometer. The HCG cantilever shows comparable signal to noise ratio to a low-end commercial FTIR system and exhibits a linear response to incident IR power.

  6. Practical method and device for enhancing pulse contrast ratio for lasers and electron accelerators

    DOEpatents

    Zhang, Shukui; Wilson, Guy

    2014-09-23

    An apparatus and method for enhancing pulse contrast ratios for drive lasers and electron accelerators. The invention comprises a mechanical dual-shutter system wherein the shutters are placed sequentially in series in a laser beam path. Each shutter of the dual shutter system has an individually operated trigger for opening and closing the shutter. As the triggers are operated individually, the delay between opening and closing first shutter and opening and closing the second shutter is variable providing for variable differential time windows and enhancement of pulse contrast ratio.

  7. Design of high ratio middle infrared continuous zoom optical system

    NASA Astrophysics Data System (ADS)

    Fan, Zheyuan; Cao, Jianzhong; Yang, Hongtao; Qu, Enshi; Wu, Dengshan

    2011-08-01

    In recent years, the demand for infrared zoom systems is increasing in proportion with the development of infrared technology and its applications. To meet this demand a variety of zoom lenses have been designed. Infrared cameras operating in the 3-5μm spectral band are used in a wide variety of applications such as targeting, rescue, guidance and surveillance systems as well as other equipment. This paper using cool 320×240 detector with staring focal plane array and secondary imaging, a mid-wave optical system using mechanical-compensated with large-aperture and a zoom range of 10:1 is designed. The Pixel Dimensions of the detector is 30μm, and the wavelength between 3.7μm ~4.8μm.The system adopts negative group variable times and positive group of compensation which can realize 33mm~330mm continuous zoom and FOV =20.61°~2.08° ,it consists of 7 lenses including 3 aspheric surface. The length of the system is 262mm with the reflection mirror multipass optical path. The results show that the modulation transfer function(MTF)are above 0.4 within the whole focal range at spatial frequency of 17 lp/mm, and Root Mean Square (RMS) value of spot diameter were smaller than the Pixel Dimensions. After the image quality being optimized, the narcissus analysis is done and 100% cold shield efficiency is obtained. Finallythe monotonic and smooth Cam curve is given. The curve shows that the imaging plane is stable and the cam is easy to process. The system has advantages of simple structure, high image quality and short zoom path etc.

  8. Calculation of Intensity Ratios of Observed Infrared [Fe II] Lines

    NASA Astrophysics Data System (ADS)

    Deb, Narayan C.; Hibbert, Alan

    2010-03-01

    Two recent observational studies of the [Fe II] λ12567/λ16435 line ratio by Smith & Hartigan and Rodriguez-Ardila et al. have suggested that the available theoretical A-values could be incorrect to 10%-40%. We have carried out an extensive configuration interaction calculation of [Fe II] lines to investigate this claim, as well as the variability in observed line ratios for λ8617/λ9052 and λ8892/λ9227 of Dennefeld. For these transitions, we are generally in good agreement with the results of Nussbaumer & Storey, less so with those of Quinet et al. In comparison, the ratios derived from observations appear either to be less secure, or other factors influence those results.

  9. Visualized numerical assessment for near infrared diffuse optical tomography with contrast-and-size detail analysis

    NASA Astrophysics Data System (ADS)

    Chen, Liang-Yu; Pan, Min-Cheng; Pan, Min-Chun

    2013-01-01

    The purpose of this study is to propose an objective contrast-and-size detail (CSD) analysis for near infrared diffuse optical tomography (NIR DOT), of which the concept is derived from the subjective contrast detail (CD) analysis. We define a measure for numerical CSD analysis based on the resolution estimation of contrast and size. Following that, the contrast-and-size map of resolution can be calculated and displayed for each corresponding image in the map; furthermore, a CSD resolution curve can be plotted by calculating the average value of the projection corresponding to the physical quantity/axis (size or contrast). To provide some worked examples about the proposed CSD analysis evaluating the imaging performance of different reconstruction methods, Tikhonov regularization and edge-preserving regularization with different weighting functions were employed. Results suggested that using edge-preserving regularization with the generalized Lorentzian weighting function is the most attractive for the estimation of absorption-coefficient images.

  10. Rock-type discrimination from ratioed infrared scanner images of Pisgah Crater, California.

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.; Thomson, F. J.

    1972-01-01

    The radiances in two thermal infrared channels of an airborne scanner system were ratioed to produce images that recorded compositionally diagnostic emittance variations for several silicate rock types near Pisgah Crater, California. The images demonstrate that the ratio method is capable of enhancing emittance variations in the presence of temperature extremes that differ by no more than 25 C, with no temperature corrections.

  11. Measurement of the optimum surround ratio inducing the highest perceived image contrast

    NASA Astrophysics Data System (ADS)

    Baek, Ye Seul; Kim, Youn Jin; Kim, Hong-Suk; Park, Seung-Ok

    2010-10-01

    Much research has shown that perceived image contrast increases as the surround luminance increases, but a number of recent studies reported opposite trends under higher surround luminance levels. We measured the change in perceived image contrast under a wide range of surround luminance levels covering from dark up to 2087 cd/m2. A large-area illuminator was used to illuminate the surround. It consists of 23 dimmable fluorescent lamps and a diffuser. Its maximum luminance is 2087 cd/m2 and could be adjusted to six lower levels. A set of paired comparison experiments was conducted to compare the perception of image contrast under seven different surround luminance levels. The results showed that the perceived image contrast varies with surround luminance and the maximum perceived image contrast is found near a surround ratio (SR) of 1. As SR increases from 0 to 1, the z score is increased, which can be fully expected by the Bartleson and Breneman effect. However, it is drastically decreased in the region of SR > 1; thus, the perceived image contrast is eventually decreased.

  12. Display characterization by eye: contrast ratio and discrimination throughout the grayscale

    NASA Astrophysics Data System (ADS)

    Gille, Jennifer; Arend, Larry; Larimer, James O.

    2004-06-01

    We have measured the ability of observers to estimate the contrast ratio (maximum white luminance / minimum black or gray) of various displays and to assess luminous discrimination over the tonescale of the display. This was done using only the computer itself and easily-distributed devices such as neutral density filters. The ultimate goal of this work is to see how much of the characterization of a display can be performed by the ordinary user in situ, in a manner that takes advantage of the unique abilities of the human visual system and measures visually important aspects of the display. We discuss the relationship among contrast ratio, tone scale, display transfer function and room lighting. These results may contribute to the development of applications that allow optimization of displays for the situated viewer / display system without instrumentation and without indirect inferences from laboratory to workplace.

  13. High ambient contrast ratio OLED and QLED without a circular polarizer

    NASA Astrophysics Data System (ADS)

    Tan, Guanjun; Zhu, Ruidong; Tsai, Yi-Shou; Lee, Kuo-Chang; Luo, Zhenyue; Lee, Yuh-Zheng; Wu, Shin-Tson

    2016-08-01

    A high ambient contrast ratio display device using a transparent organic light emitting diode (OLED) or transparent quantum-dot light-emitting diode (QLED) with embedded multilayered structure and absorber is proposed and its performance is simulated. With the help of multilayered structure, the device structure allows almost all ambient light to get through the display device and be absorbed by the absorber. Because the reflected ambient light is greatly reduced, the ambient contrast ratio of the display system is improved significantly. Meanwhile, the multilayered structure helps to lower the effective refractive index, which in turn improves the out-coupling efficiency of the display system. Potential applications for sunlight readable flexible and rollable displays are emphasized.

  14. Suspended Si/air high contrast subwavelength gratings for long-wavelength infrared reflectors

    NASA Astrophysics Data System (ADS)

    Foley, Justin M.; Phillips, Jamie D.

    2013-03-01

    We report broadband reflectance in the long-wavelength infrared (LWIR, 8-12 μm) utilizing suspended-Si, high-index-contrast subwavelength gratings (HCGs). Iterative design optimization using finite element analysis software has been performed accounting for silicon's wavelength-dependent index of refraction and extinction coefficient. Grating arrays were fabricated using commercial silicon-on-insulator (SOI) substrates, photolithography and reactive ion etching; subsequent selective wet etching of SiO2 was used to provide suspended Si/air gratings. Fourier transform infrared (FTIR) spectroscopy demonstrates broadband, polarization-dependent reflectance between 8.5 and 12 μm, which agrees with the simulated response.

  15. Small animal imaging platform for quantitative assessment of short-wave infrared-emitting contrast agents

    NASA Astrophysics Data System (ADS)

    Hu, Philip; Mingozzi, Marco; Higgins, Laura M.; Ganapathy, Vidya; Zevon, Margot; Riman, Richard E.; Roth, Charles M.; Moghe, Prabhas V.; Pierce, Mark C.

    2015-03-01

    We report the design, calibration, and testing of a pre-clinical small animal imaging platform for use with short-wave infrared (SWIR) emitting contrast agents. Unlike materials emitting at visible or near-infrared wavelengths, SWIR-emitting agents require detection systems with sensitivity in the 1-2 μm wavelength region, beyond the range of commercially available small animal imagers. We used a collimated 980 nm laser beam to excite rare-earth-doped NaYF4:Er,Yb nanocomposites, as an example of a SWIR emitting material under development for biomedical imaging applications. This beam was raster scanned across the animal, with fluorescence in the 1550 nm wavelength region detected by an InGaAs area camera. Background adjustment and intensity non-uniformity corrections were applied in software. The final SWIR fluorescence image was overlaid onto a standard white-light image for registration of contrast agent uptake with respect to anatomical features.

  16. Modeling of thickness dependent infrared radiance contrast of native and crude oil covered water surfaces.

    PubMed

    Shih, Wei-Chuan; Andrews, A Ballard

    2008-07-01

    We present a model for infrared radiance contrast of native and crude oil covered water surfaces. This model is based on the so called "direct" approach by treating individual volumetric elements as incoherent radiators. The total emitted radiation is calculated by the sum of individual contributions from the oil film and the underlying water, respectively. Therefore, different temperatures can be assigned to the oil film and water assuming quasi-static temperature distribution, enabling modeling of differential heating of the oil film during daytime. This model can be applied to remote sensing, particularly, to explain the historically observed thickness-dependent contrast in native and crude oil covered sea surfaces. PMID:18607467

  17. Calculation of signal-to-noise ratio (SNR) of infrared detection system based on MODTRAN model

    NASA Astrophysics Data System (ADS)

    Lu, Xue; Li, Chuang; Fan, Xuewu

    2013-09-01

    Signal-to-noise ratio (SNR) is an important parameter of infrared detection system. SNR of infrared detection system is determined by the target infrared radiation, atmospheric transmittance, background infrared radiation and the detector noise. The infrared radiation flux in the atmosphere is determined by the selective absorption of the gas molecules, the atmospheric environment, and the transmission distance of the radiation, etc, so the atmospheric transmittance and infrared radiance flux are intricate parameters. A radiometric model for the calculation of SNR of infrared detection system is developed and used to evaluate the effects of various parameters on signal-to-noise ratio (SNR). An atmospheric modeling tool, MODTRAN, is used to model wavelength-dependent atmospheric transmission and sky background radiance. Then a new expression of SNR is deduced. Instead of using constants such as average atmospheric transmission and average wavelength in traditional method, it uses discrete values for atmospheric transmission and sky background radiance. The integrals in general expression of SNR are converted to summations. The accuracy of SNR obtained from the new method can be improved. By adopting atmospheric condition of the 1976 US standard, no clouds urban aerosols, fall-winter aerosol profiles, the typical spectrum characters of sky background radiance and transmittance are computed by MODTRON. Then the operating ranges corresponding to the threshold quantity of SNR are calculated with the new method. The calculated operating ranges are more close to the measured operating range than those calculated with the traditional method.

  18. Two-dimensional maps of the infrared-to-radio ratio in spiral galaxies

    NASA Technical Reports Server (NTRS)

    Marsh, Kenneth A.; Helou, George

    1994-01-01

    We have produced two-dimensional maps of the intensity ratio Q(sub 60) of 60 micron infrared to 20 cm radio continuum emission, for a set of 25 nearby galaxies, mostly spirals. The ratio maps were obtained from infrared images made using Infrared Astronomical Satellite (IRAS) data with the Maximum Correlation Method, and radio images made using VLA data. Before taking the ratio, the radio images were processed so as to have the same resolution properties as the infrared images; the final spatial resolution in all cases is approximately 1 min, corresponding to 1-2 kpc for most galaxies. These images allow us to study the variations for the Q(sub 60) ratio with unprecedented spatial resolution, and thus represents a major improvement over earlier work. Our new high-resolution maps confirm the slow decrease of Q(sub 60) with increasing radial distance from the nucleus, but show additional structure which is probably associated with separate sites of active star formation in the spiral arms. The maps show Q(sub 60) to be more closely related to infrared surface brightness than to the radial distance in the galaxy disk. We expect that the results will provide improved constraints on the evolution (diffusion, decay and escape) of cosmic-ray electrons in the magnetic field of the disks.

  19. IMPROVEMENTS IN ELASTOGRAPHIC CONTRAST-TO-NOISE RATIO USING SPATIAL-ANGULAR COMPOUNDING

    PubMed Central

    Techavipoo, Udomchai; Varghese, Tomy

    2005-01-01

    Spatial-angular compounding is a new technique developed for improving the signal-to-noise ratio (SNR) in elastography. Under this method, elastograms of a region-of-interest (ROI) are obtained from a spatially weighted average of local strain estimated along different insonification angles. In this article, we investigate the improvements in the strain contrast and contrast-to-noise ratio (CNR) of the spatially compounded elastograms. Spatial angular compounding is also applied and evaluated in conjunction with global temporal stretching. Quantitative experimental results obtained using a single-inclusion tissue-mimicking phantom demonstrate that the strain contrast reduces slightly but the CNR improves by around 8 to 13 dB. We also present experimental spatial angular compounding results obtained from an in vitro thermal lesion in canine liver tissue embedded in a gelatin phantom that demonstrate the improved visual characteristics (due to the improved CNR) of the compound elastogram. The experimental results provide guidelines for the practical range of maximum insonification angles and estimates of the optimum angular increment. (E-mail: tvarghese@wisc.edu) PMID:15831331

  20. Infrared and multi-type images fusion algorithm based on contrast pyramid transform

    NASA Astrophysics Data System (ADS)

    Xu, Hua; Wang, Yan; Wu, Yujing; Qian, Yunsheng

    2016-09-01

    A fusion algorithm for infrared and multi-type images based on contrast pyramid transform (CPT) combined with Otsu method and morphology is proposed in this paper. Firstly, two sharpened images are combined to the first fused image based on information entropy weighted scheme. Afterwards, two enhanced images and the first fused one are decomposed into a series of images with different dimensions and spatial frequencies. To the low-frequency layer, the Otsu method is applied to calculate the optimal segmentation threshold of the first fused image, which is subsequently used to determine the pixel values in top layer fused image. With respect to the high-frequency layers, the top-bottom hats morphological transform is employed to each layer before maximum selection criterion. Finally, the series of decomposed images are reconstructed and then superposed with the enhanced image processed by morphological gradient operation as a second fusion to get the final fusion image. Infrared and visible images fusion, infrared and low-light-level (LLL) images fusion, infrared intensity and infrared polarization images fusion, and multi-focus images fusion are discussed in this paper. Both experimental results and objective metrics demonstrate the effectiveness and superiority of the proposed algorithm over the conventional ones used to compare.

  1. Epitaxial growth of quantum rods with high aspect ratio and compositional contrast

    SciTech Connect

    Li, L. H.; Patriarche, G.

    2008-12-01

    The epitaxial growth of quantum rods (QRs) on GaAs was investigated. It was found that GaAs thickness in the GaAs/InAs superlattice used for QR formation plays a key role in improving the QR structural properties. Increasing the GaAs thickness results in both an increased In compositional contrast between the QRs and surrounding layer, and an increased QR length. QRs with an aspect ratio of up to 10 were obtained, representing quasiquantum wires in a GaAs matrix. Due to modified confinement and strain potential, such nanostructure is promising for controlling gain polarization.

  2. Use of near infrared/red radiance ratios for estimating vegetation biomass and physiological status

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.

    1977-01-01

    The application of photographic infrared/red (ir/red) reflectance or radiance ratios for the estimation of vegetation biomass and physiological status were investigated by analyzing in situ spectral reflectance data from experimental grass plots. Canopy biological samples were taken for total wet biomass, total dry biomass, leaf water content, dry green biomass, dry brown biomass, and total chlorophyll content at each sampling date. Integrated red and photographic infrared radiances were regressed against the various canopy or plot variables to determine the relative significance between the red, photographic infrared, and the ir/red ratio and the canopy variables. The ir/red ratio is sensitive to the photosynthetically active or green biomass, the rate of primary production, and actually measures the interaction between the green biomass and the rate of primary production within a given species type. The ir/red ratio resulted in improved regression significance over the red or the ir/radiances taken separately. Only slight differences were found between ir/red ratio, the ir-red difference, the vegetation index, and the transformed vegetation index. The asymptotic spectral radiance properties of the ir, red, ir/red ratio, and the various transformations were evaluated.

  3. Highly photostable, reversibly photoswitchable fluorescent protein with high contrast ratio for live-cell superresolution microscopy.

    PubMed

    Zhang, Xi; Zhang, Mingshu; Li, Dong; He, Wenting; Peng, Jianxin; Betzig, Eric; Xu, Pingyong

    2016-09-13

    Two long-standing problems for superresolution (SR) fluorescence microscopy are high illumination intensity and long acquisition time, which significantly hamper its application for live-cell imaging. Reversibly photoswitchable fluorescent proteins (RSFPs) have made it possible to dramatically lower the illumination intensities in saturated depletion-based SR techniques, such as saturated depletion nonlinear structured illumination microscopy (NL-SIM) and reversible saturable optical fluorescence transition microscopy. The characteristics of RSFPs most critical for SR live-cell imaging include, first, the integrated fluorescence signal across each switching cycle, which depends upon the absorption cross-section, effective quantum yield, and characteristic switching time from the fluorescent "on" to "off" state; second, the fluorescence contrast ratio of on/off states; and third, the photostability under excitation and depletion. Up to now, the RSFPs of the Dronpa and rsEGFP (reversibly switchable EGFP) families have been exploited for SR imaging. However, their limited number of switching cycles, relatively low fluorescence signal, and poor contrast ratio under physiological conditions ultimately restrict their utility in time-lapse live-cell imaging and their ability to reach the desired resolution at a reasonable signal-to-noise ratio. Here, we present a truly monomeric RSFP, Skylan-NS, whose properties are optimized for the recently developed patterned activation NL-SIM, which enables low-intensity (∼100 W/cm(2)) live-cell SR imaging at ∼60-nm resolution at subsecond acquisition times for tens of time points over broad field of view. PMID:27562163

  4. Infrared-active quadruple contrast FePt nanoparticles for multiple scale molecular imaging.

    PubMed

    Chou, Shang-Wei; Liu, Chien-Liang; Liu, Tzu-Ming; Shen, Yu-Fang; Kuo, Lun-Chang; Wu, Cheng-Ham; Hsieh, Tsung-Yuan; Wu, Pei-Chun; Tsai, Ming-Rung; Yang, Che-Chang; Chang, Kai-Yao; Lu, Meng-Hua; Li, Pai-Chi; Chen, Shi-Ping; Wang, Yu-Hsin; Lu, Chen-Wen; Chen, Yi-An; Huang, Chih-Chia; Wang, Churng-Ren Chris; Hsiao, Jong-Kai; Li, Meng-Lin; Chou, Pi-Tai

    2016-04-01

    A single nanomaterial with multiple imaging contrasts and functions is highly desired for multiscale theragnosis. Herein, we demonstrate single 1-1.9 μm infrared-active FePt alloy nanoparticles (FePt NPs) offering unprecedented four-contrast-in-one molecular imaging - computed tomography (CT), magnetic resonance imaging (MRI), photoacoustic (PA) imaging, and high-order multiphoton luminescence (HOMPL) microscopy. The PA response of FePt NPs outperforms that of infrared-active gold nanorods by 3- to 5.6-fold under identical excitation fluence and particle concentrations. HOMPL (680 nm) of an isolated FePt NP renders spatial full-width-at-half-maximum values of 432 nm and 300 nm beyond the optical diffraction limit for 1230-nm and 920-nm excitation, respectively. The in vivo targeting function was successfully visualized using HOMPL, PA imaging, CT, and MRI, thereby validating FePt as a single nanomaterial system covering up to four types (Optical/PA/CT/MRI) of molecular imaging contrast, ranging from the microscopic level to whole-body scale investigation. PMID:26854391

  5. An infrared small target detection algorithm based on high-speed local contrast method

    NASA Astrophysics Data System (ADS)

    Cui, Zheng; Yang, Jingli; Jiang, Shouda; Li, Junbao

    2016-05-01

    Small-target detection in infrared imagery with a complex background is always an important task in remote sensing fields. It is important to improve the detection capabilities such as detection rate, false alarm rate, and speed. However, current algorithms usually improve one or two of the detection capabilities while sacrificing the other. In this letter, an Infrared (IR) small target detection algorithm with two layers inspired by Human Visual System (HVS) is proposed to balance those detection capabilities. The first layer uses high speed simplified local contrast method to select significant information. And the second layer uses machine learning classifier to separate targets from background clutters. Experimental results show the proposed algorithm pursue good performance in detection rate, false alarm rate and speed simultaneously.

  6. A novel use of near-infrared fluorescence imaging during robotic surgery without contrast agents.

    PubMed

    Hockenberry, Mark S; Smith, Zachary L; Mucksavage, Phillip

    2014-05-01

    We describe a novel use of near-infrared fluorescence (NIRF) imaging without contrast agents, like indocyanine green, to identify otherwise obscured intraluminal areas of interest during robot-assisted laparoscopic (RAL) surgery marked by the white light (WL) of endoscopic instruments. By filtering light wavelengths below near-infrared, NIRF imaging causes the WL of the endoscopes to illuminate green while allowing simultaneous vision of the surrounding tissues. With this visualization, intraoperative ureteroscopy was used to identify the extent of a ureteral stricture in a patient undergoing RAL partial ureterectomy. Cystoscopy was used to identify bladder diverticula and tumor locations in three patients undergoing RAL partial cystectomy with or without diverticulectomy and the ureteral orifice in another patient undergoing RAL nephroureterectomy. This technique enabled more precise identification of important areas and successful completion of RAL surgery in these five patients, which serves as proof of concept for broader applications in RAL surgery. PMID:24354630

  7. Mechanically compensated type for midwave infrared zoom system with a large zoom ratio

    NASA Astrophysics Data System (ADS)

    Hao, Zhou; Ying, Liu; Qiang, Sun; Chun, Li; Xiaolong, Zhang; Jianbo, Huang

    2013-01-01

    In some circumstances, there is a need for a midwave infrared (MWIR) zoom system with a large zoom ratio. Using traditional four-component mechanically compensated types of MWIR zoom systems cannot achieve a large zoom ratio. To meet this demand, we describe a six-component mechanically compensated type. The thin-lens theory of this type is developed and equations are presented. Using the six-component mechanically compensated type, a MWIR continuous zoom system with a zoom ratio of 45 is designed, and it has high image quality over the entire zoom range.

  8. Preparation of near-infrared-labeled targeted contrast agents for clinical translation

    NASA Astrophysics Data System (ADS)

    Olive, D. Michael

    2011-03-01

    Targeted fluorophore-labeled contrast agents are moving toward translation to human surgical use. To prepare for future clinical use, we examined the performance of potential ligands targeting the epidermal growth factor receptor, α5β3 integrins, and GLUT transporters for their suitability as directed contrast agents. Each agent was labeled with IRDye 800CW, and near-infrared dye with excitation/emission wavelengths of 789/805 nm, which we determined had favorable toxicity characteristics. The probe molecules examined consisted of Affibodies, nanobodies, peptides, and the sugar 2-deoxy-D-glucose. Each probe was tested for specific and non-specific binding in cell based assays. All probe types showed good performance in mouse models for detecting either spontaneous tumors or tumor xenografts in vivo. Each of the probes tested show promise for future human clinical studies.

  9. Noise and contrast comparison of visual and infrared images of hazards as seen inside an automobile

    NASA Astrophysics Data System (ADS)

    Meitzler, Thomas J.; Bryk, Darryl; Sohn, Eui J.; Lane, Kimberly; Bednarz, David; Jusela, Daniel; Ebenstein, Samuel; Smith, Gregory H.; Rodin, Yelena; Rankin, James S., II; Samman, Amer M.

    2000-06-01

    The purpose of this experiment was to quantitatively measure driver performance for detecting potential road hazards in visual and infrared (IR) imagery of road scenes containing varying combinations of contrast and noise. This pilot test is a first step toward comparing various IR and visual sensors and displays for the purpose of an enhanced vision system to go inside the driver compartment. Visible and IR road imagery obtained was displayed on a large screen and on a PC monitor and subject response times were recorded. Based on the response time, detection probabilities were computed and compared to the known time of occurrence of a driving hazard. The goal was to see what combinations of sensor, contrast and noise enable subjects to have a higher detection probability of potential driving hazards.

  10. Pedestal cleaning for high laser pulse contrast ratio with a 100 TW class laser system.

    PubMed

    Fourmaux, S; Payeur, S; Buffechoux, S; Lassonde, P; St-Pierre, C; Martin, F; Kieffer, J C

    2011-04-25

    Laser matter interaction at relativistic intensities using 100 TW class laser systems or higher is becoming more and more widespread. One of the critical issues of such laser systems is to let the laser pulse interact at high intensity with the solid target and avoid any pre-plasma. Thus, a high Laser Pulse Contrast Ratio (LPCR) parameter is of prime importance. We present the LPCR characterization of a high repetition 100 TW class laser system. We demonstrate that the generated Amplified Spontaneous Emission (ASE) degrades the overall LPCR performance. We propose a simple way to clean the pulse after the first amplification stage by introducing a solid state saturable absorber which results in a LPCR improvement to better than 10(10) with only a 30% energy loss at a 10 Hz repetition rate. We finally correlated this cleaning method with experimental results. PMID:21643098

  11. Contrast ratio enhancement in a saturable absorber-based photonic analog-to-digital converter

    NASA Astrophysics Data System (ADS)

    Hayduk, Michael J.; Bussjager, Rebecca J.; Johns, Steven T.; Gerhardstein, Cheryl M.; Wicks, Gary W.

    2002-07-01

    Optical processing techniques are expected to play a key role in the next generation of advanced high-speed analog- to-digital converters (ADCs). These techniques will alleviate the current limitations inherent in conventional electronic ADCs. We are currently developing a novel photonic ADC module that incorporates the use of semiconductor saturable absorbers to perform the data quantization at speeds in the tens of GHz regime. Results will be presented for the experimental material characterization of the semiconductor saturable absorbers used in the data conversion process. Enhancement of the contrast ratio of the saturable absorber between the 'on' state and the 'off' state can also be greatly enhanced by the use of an asymmetric Fabry-Perot etalon. Initial experimental results for a saturable absorber contained within an etalon will also be presented.

  12. Extreme Contrast Ratio Imaging of Sirius with a Charge Injection Device

    NASA Astrophysics Data System (ADS)

    Batcheldor, D.; Foadi, R.; Bahr, C.; Jenne, J.; Ninkov, Z.; Bhaskaran, S.; Chapman, T.

    2016-02-01

    The next fundamental steps forward in understanding our place in the universe could be a result of advances in extreme contrast ratio (ECR) imaging and point-spread function (PSF) suppression. For example, blinded by quasar light we have yet to fully understand the processes of galaxy and star formation and evolution, and there is an ongoing race to obtain a direct image of an exo-Earth lost in the glare of its host star. To fully explore the features of these systems, we must perform observations in which contrast ratios (CRs) of at least one billion can be regularly achieved with sub 0.″1 inner working angles. Here, we present the details of a latest-generation 32-bit charge injection device (CID) that could conceivably achieve CRs on the order of one billion. We also demonstrate some of its ECR imaging abilities for astronomical imaging. At a separation of two arcminutes, we report a direct CR of {{Δ }}{m}v=18.3,{log}({CR})=7.3, or 1 part in 20 million, from observations of the Sirius field. The atmospheric conditions present during the collection of this data prevented less modest results, and we expect to be able to achieve higher CRs, with improved inner working angles, simply by operating a CID at a world-class observing site. However, CIDs do not directly provide any PSF suppression. Therefore, combining CID imaging with a simple PSF suppression technique like angular differential imaging could provide a cheap and easy alternative to the complex ECR techniques currently being employed.

  13. Virus-mimicking nano-constructs as a contrast agent for near infrared photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Gupta, Sharad; Chatni, Muhammad R.; Rao, Ayala L. N.; Vullev, Valentine I.; Wang, Lihong V.; Anvari, Bahman

    2013-02-01

    We report the first proof-of-principle demonstration of photoacoustic imaging using a contrast agent composed of a plant virus protein shell, which encapsulates indocyanine green (ICG), the only FDA-approved near infrared chromophore. These nano-constructs can provide higher photoacoustic signals than blood in tissue phantoms, and display superior photostability compared to non-encapsulated ICG. Our preliminary results suggest that the constructs do not elicit an acute immunogenic response in healthy mice.We report the first proof-of-principle demonstration of photoacoustic imaging using a contrast agent composed of a plant virus protein shell, which encapsulates indocyanine green (ICG), the only FDA-approved near infrared chromophore. These nano-constructs can provide higher photoacoustic signals than blood in tissue phantoms, and display superior photostability compared to non-encapsulated ICG. Our preliminary results suggest that the constructs do not elicit an acute immunogenic response in healthy mice. Electronic supplemental information (ESI) available: Information on experimental procedure for fabrication of the nano-constructs, photoacoustic imaging, and immunogenic studies. See DOI: 10.1039/c3nr34124k

  14. A consideration of the signal-to-noise ratio in phase contrast mammography

    NASA Astrophysics Data System (ADS)

    Kato, Yuri; Fujita, Naotoshi; Kodera, Yoshie

    2010-04-01

    Recently, with developments in medicine, digital systems such as computed radiography (CR) and flat-panel detector (FPD) systems are being employed for mammography instead of analog systems such as the screen-film system. Phase-contrast mammography (PCM) is a commercially available digital system that uses images with a magnification of 1.75x. To study the effect of the air gap in PCM, we measured the scatter fraction ratio (SFR) and calculated the signal-to-noise ratio (SNR) in PCM, and compared it to that in conventional mammography (CM). Then, to extend the SNR to the spatial frequency domain, we calculated the noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) used by the modulation transfer function (MTF), noise power spectrum of the pixel value (NPSΔPV), gradient of the digital characteristic curve, and number of X-ray photons. The obtained results indicated that the SFR of the PCM was as low as that of the CM with a grid. When the exposure dose was constant, the SNR of the PCM was the highest in all systems. Moreover, the NEQ and DQE for the PCM were higher than those for the CM (G-) in the spatial frequency domain over 2.5 cycles/mm. These results showed that the number of scattered X-rays was reduced sufficiently by the air gap in the PCM and the NEQ and DQE for PCM were influenced by the presampled MTF in the high-spatial-frequency domain.

  15. GaAs/AlOx high-contrast grating mirrors for mid-infrared VCSELs

    NASA Astrophysics Data System (ADS)

    Almuneau, G.; Laaroussi, Y.; Chevallier, C.; Genty, F.; Fressengeas, N. s.; Cerutti, L.; Gauthier-Lafaye, Olivier

    2015-02-01

    Mid-infrared Vertical cavity surface emitting lasers (MIR-VCSEL) are very attractive compact sources for spectroscopic measurements above 2μm, relevant for molecules sensing in various application domains. A long-standing issue for long wavelength VCSEL is the large structure thickness affecting the laser properties, added for the MIR to the tricky technological implementation of the antimonide alloys system. In this paper, we propose a new geometry for MIR-VCSEL including both a lateral confinement by an oxide aperture, and a high-contrast sub-wavelength grating mirror (HCG mirror) formed by the high contrast combination AIOx/GaAs in place of GaSb/A|AsSb top Bragg reflector. In addition to drastically simplifying the vertical stack, HCG mirror allows to control through its design the beam properties. The robust design of the HCG has been ensured by an original method of optimization based on particle swarm optimization algorithm combined with an anti-optimization one, thus allowing large error tolerance for the nano-fabrication. Oxide-based electro-optical confinement has been adapted to mid-infrared lasers, byusing a metamorphic approach with (Al) GaAs layer directly epitaxially grown on the GaSb-based VCSEL bottom structure. This approach combines the advantages of the will-controlled oxidation of AlAs layer and the efficient gain media of Sb-based for mid-infrared emission. We finally present the results obtained on electrically pumped mid-IR-VCSELs structures, for which we included oxide aperturing for lateral confinement and HCG as high reflectivity output mirrors, both based on AlxOy/GaAs heterostructures.

  16. The branching ratio in the infrared predissociation of aniline-water-methanol + ion

    NASA Astrophysics Data System (ADS)

    Alauddin, Md.; Song, Jae Kyu; Park, Seung Min

    2010-09-01

    The infrared (IR) photodissociation of aniline-water-methanol cluster ion was investigated in the 2600-3900 cm -1 region to examine the factors which play key roles in determining the branching ratio of a concurrent predissociation reaction. The dominant channel in the IR predissociation of AWM + (A: aniline, W: water, M: methanol) was AWM + → AM + at all vibrational modes although the calculated binding energies of water and methanol were nearly the same. Also, the branching ratio was slightly dependent on the specific excited mode, ranging from 0.036 to 0.074; the most effective mode to kick out methanol was OH vibration of methanol.

  17. Fine-structure collision strengths and line ratios for [Ne V] in infrared and optical sources

    NASA Astrophysics Data System (ADS)

    Dance, Michael; Palay, Ethan; Nahar, Sultana N.; Pradhan, Anil K.

    2013-10-01

    New collisions' strengths for the mid-infrared (mid-IR) and optical transitions in Ne V are presented. Breit-Pauli-R-Matrix calculations for electron impact excitation are carried out with fully resolved near-threshold resonances at very low energies. In particular, the fine-structure lines at 14 and 24 μm due to transitions among the ground state levels 1s22s22p3 3P0, 1, 2, and the optical/near-ultraviolet lines at 2973, 3346 and 3426 Å transitions among the 3P0, 1, 2, 1D2, 1S0 levels are described. Maxwellian-averaged collision strengths are tabulated for all forbidden transitions within the ground configuration. While some significant differences are found for both the far infrared and the optical transitions compared to previous results, computed line emissivity ratios are in good agreement, but change rapidly in the low temperature range Te < 10 000 K. An analysis of the 14/24 μm ratio in low-energy-density (LED) plasma conditions reveals considerable variation; the effective rate coefficient may be dominated by the very low energy behaviour rather than the Maxwellian-averaged collision strengths. Computed values suggest a possible solution to the anomalous mid-IR ratios found to be lower than theoretical limits observed from planetary nebulae and Seyfert galaxies. While such LED conditions may be present in infrared sources, they might be inconsistent with photoionization equilibrium models.

  18. High contrast ratio and fast-switching dual polymer electrochromic devices

    SciTech Connect

    Sapp, S.A.; Sotzing, G.A.; Reynolds, J.R.

    1998-08-01

    A series of dual polymer electrochromic devices (ECDs) based on 12 complementary pairs of conducting polymer films have been constructed using 3,4-ethylenedioxythiophene-containing conducting polymers. Poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-methylcarbazole] (PBEDOT-NCH{sub 3}Cz), poly[3,6-bis(2-(3,4-ethylenedioxythiophene))-N-eicosylcarbazole] (PBEDOT-NC{sub 20}H{sub 41}Cz), and poly[4,4{prime}-bis(2-(3,4-ethylenedioxythiophene))biphenyl] (PBEDOT-BP) were utilized as anodically coloring polymers that electrochemically switch between an oxidized deep blue absorptive state and a transmissive (orange or yellow) reduced state. Poly(3,4-ethylenedioxythiophene)(PEDOT) and its alkyl derivatives (PEDOT-C{sub 14}H{sub 29} and PEDOT-C{sub 16}H{sub 33}) have been used as high-contrast cathodically coloring polymers that switch between a deep blue absorptive state in the reduced form and a sky blue, highly transmissive state in the oxidized form. The dual polymer ECDs were constructed by separating complementary pairs of EC polymer films, deposited on ITO glass, with a gel electrolyte composed of a lithium salt and plasticized poly(methyl methacrylate) (PMMA). Device contrast ratios, measured as {Delta}%T, ranged from 27% to 63%, and subsecond switching times for full color change were achieved. These devices were found to exhibit extremely high coloration efficiencies of up to 1400 cm{sup 2}/C over narrow (ca. 100 nm) wavelength ranges and to retain up to 60% of their optical response after 10,000 deep, double potential steps, rendering them useful for EC applications.

  19. Sedimentary Sulphur:Iron Ratio Indicates Vivianite Occurrence: A Study from Two Contrasting Freshwater Systems

    PubMed Central

    Rothe, Matthias; Kleeberg, Andreas; Grüneberg, Björn; Friese, Kurt; Pérez-Mayo, Manuel; Hupfer, Michael

    2015-01-01

    An increasing number of studies constrain the importance of iron for the long-term retention of phosphorus (P) under anoxic conditions, i.e. the formation of reduced iron phosphate minerals such as vivianite (Fe3(PO4)2⋅8H2O). Much remains unknown about vivianite formation, the factors controlling its occurrence, and its relevance for P burial during early sediment diagenesis. To study the occurrence of vivianite and to assess its relevance for P binding, surface sediments of two hydrologically contrasting waters were analysed by heavy-liquid separation and subsequent powder X-ray diffraction. In Lake Arendsee, vivianite was present in deeper sediment horizons and not in the uppermost layers with a sharp transition between vivianite and non-vivianite bearing layers. In contrast, in lowland river Lower Havel vivianite was present in the upper sediment layers and not in deeper horizons with a gradual transition between non-vivianite and vivianite bearing layers. In both waters, vivianite occurrence was accompanied by the presence of pyrite (FeS2). Vivianite formation was favoured by an elevated iron availability through a lower degree of sulphidisation and was present at a molar ratio of total sulphur to reactive iron smaller than 1.1, only. A longer lasting burden of sediments by organic matter, i.e. due to eutrophication, favours the release of sulphides, and the formation of insoluble iron sulphides leading to a lack of available iron and to less or no vivianite formation. This weakening in sedimentary P retention, representing a negative feedback mechanism (P release) in terms of water quality, could be partly compensated by harmless Fe amendments. PMID:26599406

  20. Sedimentary Sulphur:Iron Ratio Indicates Vivianite Occurrence: A Study from Two Contrasting Freshwater Systems.

    PubMed

    Rothe, Matthias; Kleeberg, Andreas; Grüneberg, Björn; Friese, Kurt; Pérez-Mayo, Manuel; Hupfer, Michael

    2015-01-01

    An increasing number of studies constrain the importance of iron for the long-term retention of phosphorus (P) under anoxic conditions, i.e. the formation of reduced iron phosphate minerals such as vivianite (Fe3(PO4)2⋅8H2O). Much remains unknown about vivianite formation, the factors controlling its occurrence, and its relevance for P burial during early sediment diagenesis. To study the occurrence of vivianite and to assess its relevance for P binding, surface sediments of two hydrologically contrasting waters were analysed by heavy-liquid separation and subsequent powder X-ray diffraction. In Lake Arendsee, vivianite was present in deeper sediment horizons and not in the uppermost layers with a sharp transition between vivianite and non-vivianite bearing layers. In contrast, in lowland river Lower Havel vivianite was present in the upper sediment layers and not in deeper horizons with a gradual transition between non-vivianite and vivianite bearing layers. In both waters, vivianite occurrence was accompanied by the presence of pyrite (FeS2). Vivianite formation was favoured by an elevated iron availability through a lower degree of sulphidisation and was present at a molar ratio of total sulphur to reactive iron smaller than 1.1, only. A longer lasting burden of sediments by organic matter, i.e. due to eutrophication, favours the release of sulphides, and the formation of insoluble iron sulphides leading to a lack of available iron and to less or no vivianite formation. This weakening in sedimentary P retention, representing a negative feedback mechanism (P release) in terms of water quality, could be partly compensated by harmless Fe amendments. PMID:26599406

  1. C/O abundance ratios, iron depletions, and infrared dust features in galactic planetary nebulae

    SciTech Connect

    Delgado-Inglada, Gloria; Rodríguez, Mónica E-mail: mrodri@inaoep.mx

    2014-04-01

    We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O ≳ 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

  2. C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Delgado-Inglada, Gloria; Rodríguez, Mónica

    2014-04-01

    We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O <1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O >~ 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

  3. Assessment of the Contrast to Noise Ratio in PET Scanners with Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Karpetas, G. E.; Fountos, G. P.; Valais, I. G.; Nikolopoulos, D.; Kandarakis, I. S.; Panayiotakis, G. S.

    2015-09-01

    The aim of the present study was to assess the contrast to noise ratio (CNR) of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction. The PET scanner simulated was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution. Image quality was assessed in terms of the CNR. CNR was estimated from coronal reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL. OSMAPOSL reconstruction was assessed by using various subsets (3, 15 and 21) and various iterations (2 to 20). CNR values were found to decrease when both iterations and subsets increase. Two (2) iterations were found to be optimal. The simulated PET evaluation method, based on the TLC plane source, can be useful in image quality assessment of PET scanners.

  4. A novel method for contrast-to-noise ratio (CNR) evaluation of digital mammography detectors.

    PubMed

    Baldelli, P; Phelan, N; Egan, G

    2009-09-01

    The purpose of this study was to test a new, simple method of evaluating the contrast-to-noise ratio (CNR) over the entire image field of a digital detector and to compare different mammography systems. Images were taken under clinical exposure conditions for a range of simulated breast thicknesses using poly(methyl methacrylate) (PMMA). At each PMMA thickness, a second image which included an additional 0.2-mm Al sheet was also acquired. Image processing software was used to calculate the CNR in multiple regions of interest (ROI) covering the entire area of the detector in order to obtain a 'CNR image'. Five detector types were evaluated, two CsI-alphaSi (GE Healthcare) flat panel systems, one alphaSe (Hologic) flat panel system and a two generations of scanning photon counting digital detectors (Sectra). Flat panel detectors exhibit better CNR uniformity compared with the first-generation scanning photon counting detector in terms of mean pixel value variation. However, significant improvement in CNR uniformity was observed for the next-generation scanning detector. The method proposed produces a map of the CNR and a measurement of uniformity throughout the entire image field of the detector. The application of this method enables quality control measurement of individual detectors and a comparison of detectors using different technologies. PMID:19424702

  5. Contrast-to-noise ratio improvement in volume-of-interest cone beam breast CT

    NASA Astrophysics Data System (ADS)

    Shen, Youtao; Liu, Xinming; Lai, Chao-Jen; Zhong, Yuncheng; Yi, Ying; You, Zhicheng; Wang, Tianpeng; Shaw, Chris C.

    2012-03-01

    In this study, we demonstrated the contrast-to-noise ratio (CNR) improvement in breast cone beam CT (CBCT) using the volume-of-interest (VOI) scanning technique. In VOI breast CBCT, the breast is first scanned at a low exposure level. A pre-selected VOI is then scanned at a higher exposure level with collimated x-rays. The two image sets are combined together to reconstruct high quality 3-D images of the VOI. A flat panel detector based system was built to demonstrate and investigate the CNR improvement in VOI breast CBCT. The CNRs of the 8 plastic cones (Teflon, Delrin, polycarbonate, Lucite, solid water, high density polystyrene, nylon and polystyrene) in a breast phantom were measured in images obtained with the VOI CBCT technique and compared to those measured in standard full field CBCT images. CNRs in VOI CBCT images were found to be higher than those in regular CBCT images in all plastic cones. The mean glandular doses (MGDs) from the combination of a high exposure VOI scan and a low exposure full-field scan was estimated to be similar to that from regular full-field scan at standard exposure level. The VOI CBCT technique allows a VOI to be imaged with enhanced image quality with an MGD similar to that from regular CBCT technique.

  6. Surface roughness limited contrast to clutter ratios THz medical imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sung, Shijun; Bajwa, Neha; Goell, Jacob; Taylor, Zachary

    2016-03-01

    The THz electromagnetic properties of rough surface are explored and their effect on the observed contrast in THz images is quantified. Rough surface scatter is a major source of clutter in THz imaging as the rough features of skin and other tissues result in non-trivial reflection signal modulation. Traditional approaches to data collection utilize dielectric windows to flatten surfaces for THz imaging. However, there is substantial interest surrounding window free imaging as contact measurements are not ideal for a range of candidate diseases and injuries. In this work we investigate the variation in reflected signal in the specular direction from rough surfaces targets with known roughness parameters. Signal to clutter ratios are computed and compared with that predicted by Rayleigh Rough surface scattering theory. It is shown that Rayleigh rough surface scattering theory, developed for rough features larger than the interacting wavelength, holds acceptable at THz frequencies with rough features much smaller than the wavelength. Additionally, we present some biological tissue imaging examples to illustrate the impact of rough surface scattering in image quality.

  7. Near infrared transillumination imaging of breast cancer with vasoactive inhalation contrast

    PubMed Central

    Dixit, Sanhita S.; Kim, Hanyoup; Comstock, Christopher; Faris, Gregory W.

    2010-01-01

    Inhalation of vasoactive gases such as carbon dioxide and oxygen can provide strong changes in tissue hemodynamics. In this report, we present a preliminary clinical study aimed at assessing the feasibility of inhalation-based contrast with near infrared continuous wave transillumination for breast imaging. We describe a method for fitting the transient absorbance that provides the wavelength dependence of the optical pathlength as parametrized by tissue oxygenation and scatter power as well as the differential changes in oxy- and deoxy-hemoglobin. We also present a principal component analysis data reduction technique to assess the dynamic response from the tissue that uses coercion to provide single temporal eigenvalues associated with both oxy- and deoxy-hemoglobin changes. PMID:21258467

  8. D/H RATIO OF TITAN FROM OBSERVATIONS OF THE CASSINI/COMPOSITE INFRARED SPECTROMETER

    SciTech Connect

    Abbas, M. M.; LeClair, A.; Kandadi, H. E-mail: andre.c.leClair@nasa.go

    2010-01-01

    The Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft, launched in 1997 October and inserted into Saturn's orbit in 2004 July for exploration of the Saturnian system, has been making observations of Titan during its close flybys. The infrared spectra of Titan observed over a wide range of latitudes cover the 10-1400 cm{sup -1} spectral region with variable apodized resolutions from 0.53 to 15 cm{sup -1}. The spectra exhibit features of the nu{sub 4} band of methane (CH{sub 4}) in the 1300 cm{sup -1} region, and the deuterated isotope of methane (CH{sub 3}D) centered around 1156 cm{sup -1}, along with features of many trace constituents in other spectral regions, comprising hydrocarbons and nitriles in Titan's atmosphere. An analysis of the observed infrared spectra in the 1300 cm{sup -1} and 1156 cm{sup -1} regions, respectively, permits retrieval of the thermal structure and the CH{sub 3}D distributions of Titan's atmosphere. In this paper, we present a comprehensive analysis of the CIRS infrared spectra for retrieval of the CH{sub 3}D abundance and the corresponding D/H ratio in Titan's atmosphere. The analysis is based on the 0.53 cm{sup -1} resolution infrared spectra obtained during the Titan flybys from 2004 July 3 to 2008 May 28 over a range of latitudes extending from 74.{sup 0}4 N to 84.{sup 0}9 S. Using the CH{sub 4} mixing ratio of 1.4 x 10{sup -2} as measured by the Gas Chromatograph and Mass Spectrometer on the Huygens probe on the Cassini mission, we determine the D/H ratio of Titan as (1.58 +- 0.16) x 10{sup -4}, where the 1sigma uncertainty includes the standard deviation due to spectral noise and the estimated errors arising from uncertainties in the temperature retrieval, the mixing ratio of CH{sub 4}, and the spectral line parameters. Comparison of this value with the previously measured values for Titan as well as in other astrophysical sources, and its possible implications are discussed.

  9. Real-Time Intraoperative Near-Infrared Fluorescence Identification of the Extrahepatic Bile Ducts using Clinically-Available Contrast Agents

    PubMed Central

    Matsui, Aya; Tanaka, Eiichi; Choi, Hak Soo; Winer, Joshua H.; Kianzad, Vida; Gioux, Sylvain; Laurence, Rita G.; Frangioni, John V.

    2009-01-01

    Background Iatrogenic bile duct injuries are serious complications with patient morbidity. We hypothesized that the invisible near-infrared (NIR) fluorescence properties of methylene blue (MB) and indocyanine green (ICG) could be exploited for real-time, intraoperative imaging of the extrahepatic bile ducts during open and laparoscopic surgeries. Methods 2.0 mg/kg of MB and 0.05 mg/kg of ICG were intravenously injected into 35-kg female Yorkshire pigs and the extrahepatic bile ducts imaged over time using either the FLARE™ image-guided surgery system (open surgery) or a custom NIR fluorescence laparoscopy system. Surgical anatomy was confirmed using x-ray cholangiography. Contrast-to-background ratio (CBR), contrast-to-liver ratio (CLR), and chemical concentrations in the cystic duct (CD) and common bile duct (CBD) were measured, and the performance of each agent quantified. Results Using NIR fluorescence of MB, the CD and CBD could be identified with good sensitivity (CBR and CLR ≥ 4), during both open and laparoscopic surgeries, from 10 to 120 min post-injection. Functional impairment of the ducts, including constriction and injury were immediately identifiable. Using NIR fluorescence of ICG, extrahepatic bile ducts did not become visible until 90 min post-injection due to strong residual liver retention, however, between 90 to 240 min, ICG provided exquisitely high sensitivity for both CD and CBD, with CBR ≥ 8 and CLR ≥ 4. Conclusions We demonstrate that two clinically available NIR fluorophores, MB fluorescing at 700 nm and ICG fluorescing at 800 nm, provide sensitive, prolonged identification of the extrahepatic bile ducts and assessment of their functional status. PMID:20117813

  10. Classification of structurally related commercial contrast media by near infrared spectroscopy.

    PubMed

    Yip, Wai Lam; Soosainather, Tom Collin; Dyrstad, Knut; Sande, Sverre Arne

    2014-03-01

    Near infrared spectroscopy (NIRS) is a non-destructive measurement technique with broad application in pharmaceutical industry. Correct identification of pharmaceutical ingredients is an important task for quality control. Failure in this step can result in several adverse consequences, varied from economic loss to negative impact on patient safety. We have compared different methods in classification of a set of commercially available structurally related contrast media, Iodixanol (Visipaque(®)), Iohexol (Omnipaque(®)), Caldiamide Sodium and Gadodiamide (Omniscan(®)), by using NIR spectroscopy. The performance of classification models developed by soft independent modelling of class analogy (SIMCA), partial least squares discriminant analysis (PLS-DA) and Main and Interactions of Individual Principal Components Regression (MIPCR) were compared. Different variable selection methods were applied to optimize the classification models. Models developed by backward variable elimination partial least squares regression (BVE-PLS) and MIPCR were found to be most effective for classification of the set of contrast media. Below 1.5% of samples from the independent test set were not recognized by the BVE-PLS and MIPCR models, compared to up to 15% when models developed by other techniques were applied. PMID:24374816

  11. Dynamic range reduction and contrast adjustment of infrared images in surveillance scenarios

    NASA Astrophysics Data System (ADS)

    Rossi, Alessandro; Acito, Nicola; Diani, Marco; Corsini, Giovanni

    2013-10-01

    The high thermal sensitivity of modern infrared (IR) cameras allows us to distinguish objects with small temperature variations. In comparison with the dynamics of standard displays, the sensed IR images have a high dynamic range (HDR). In this context, suitable techniques to display HDR images are required in order to improve the visibility of the details without introducing distortions. In the recent literature of IR image processing, a common framework to perform HDR image visualization relies on DR reduction (DRR) with a cascaded processing for local contrast adjustment (CA). In this work, a novel method, named cluster-based DRR and contrast adjustment (CDCA) is introduced for the visualization of IR images. The CDCA method is composed of two cascaded steps: (1) DRR clustering-based approach and (2) a CA module specifically designed to account for IR image features. The effectiveness of the introduced technique is analyzed using IR images of surveillance scenarios collected in different operating conditions. The results are compared with those given by other IR-HDR visualization methods and show the benefits of the proposed CDCA in terms of details enhancement, robustness against the horizon effect and presence of hot objects.

  12. Low-dose, phase-contrast mammography with high signal-to-noise ratio.

    PubMed

    Gromann, Lukas B; Bequé, Dirk; Scherer, Kai; Willer, Konstantin; Birnbacher, Lorenz; Willner, Marian; Herzen, Julia; Grandl, Susanne; Hellerhoff, Karin; Sperl, Jonathan I; Pfeiffer, Franz; Cozzini, Cristina

    2016-02-01

    Differential phase-contrast X-ray imaging using a Talbot-Lau interferometer has recently shown promising results for applications in medical imaging. However, reducing the applied radiation dose remains a major challenge. In this study, we consider the realization of a Talbot-Lau interferometer in a high Talbot order to increase the signal-to-noise ratio for low-dose applications. The quantitative performance of π and π/2 systems at high Talbot orders is analyzed through simulations, and the design energy and X-ray spectrum are optimized for mammography. It is found that operation even at very high Talbot orders is feasible and beneficial for image quality. As long as the X-ray spectrum is matched to the visibility spectrum, the SNR continuously increases with the Talbot order for π-systems. We find that the optimal X-ray spectra and design energies are almost independent of the Talbot order and that the overall imaging performance is robust against small variations in these parameters. Discontinuous spectra, such as that from molybdenum, are less robust because the characteristic lines may coincide with minima in the visibility spectra; however, they may offer slightly better performance. We verify this hypothesis by realizing a prototype system with a mean fringe visibility of above 40% at the seventh Talbot order. With this prototype, a proof-of-principle measurement of a freshly dissected breast at reasonable compression to 4 cm is conducted with a mean glandular dose of only 3 mGy but with a high SNR. PMID:26977347

  13. Low-dose, phase-contrast mammography with high signal-to-noise ratio

    PubMed Central

    Gromann, Lukas B.; Bequé, Dirk; Scherer, Kai; Willer, Konstantin; Birnbacher, Lorenz; Willner, Marian; Herzen, Julia; Grandl, Susanne; Hellerhoff, Karin; Sperl, Jonathan I.; Pfeiffer, Franz; Cozzini, Cristina

    2016-01-01

    Differential phase-contrast X-ray imaging using a Talbot-Lau interferometer has recently shown promising results for applications in medical imaging. However, reducing the applied radiation dose remains a major challenge. In this study, we consider the realization of a Talbot-Lau interferometer in a high Talbot order to increase the signal-to-noise ratio for low-dose applications. The quantitative performance of π and π/2 systems at high Talbot orders is analyzed through simulations, and the design energy and X-ray spectrum are optimized for mammography. It is found that operation even at very high Talbot orders is feasible and beneficial for image quality. As long as the X-ray spectrum is matched to the visibility spectrum, the SNR continuously increases with the Talbot order for π-systems. We find that the optimal X-ray spectra and design energies are almost independent of the Talbot order and that the overall imaging performance is robust against small variations in these parameters. Discontinuous spectra, such as that from molybdenum, are less robust because the characteristic lines may coincide with minima in the visibility spectra; however, they may offer slightly better performance. We verify this hypothesis by realizing a prototype system with a mean fringe visibility of above 40% at the seventh Talbot order. With this prototype, a proof-of-principle measurement of a freshly dissected breast at reasonable compression to 4 cm is conducted with a mean glandular dose of only 3 mGy but with a high SNR. PMID:26977347

  14. Trabecular bone histomorphometric measurements and contrast-to-noise ratio in CBCT

    PubMed Central

    Smedby, Ö; Brismar, T B; Moreno, R

    2014-01-01

    Objectives: The aim of this study was to evaluate how imaging parameters at clinical dental CBCT affect the accuracy in quantifying trabecular bone structures, contrast-to-noise ratio (CNR) and radiation dose. Methods: 15 radius samples were examined using CBCT (Accuitomo FPD; J. Morita Mfg., Kyoto, Japan). Nine imaging protocols were used, differing in current, voltage, rotation degree, voxel size, imaging area and rotation time. Radiation doses were measured using a kerma area product-meter. After segmentation, six bone structure parameters and CNRs were quantified. Micro-CT (μCT) images with an isotropic resolution of 20 μm were used as a gold standard. Results: Structure parameters obtained by CBCT were strongly correlated to those by μCT, with correlation coefficients >0.90 for all studied parameters. Bone volume and trabecular thickness were not affected by changes in imaging parameters. Increased tube current from 5 to 8 mA, decreased isotropic voxel size from 125 to 80 μm and decreased rotation angle from 360° to 180° affected correlations for trabecular termini negatively. Decreasing rotation degree also weakened correlations for trabecular separation and trabecular number at 80 μm voxel size. Changes in the rotation degree and tube current affected CNR significantly. The radiation dose varied between 269 and 1153 mGy cm2. Conclusions: Trabecular bone structure can be accurately quantified by clinical dental CBCT in vitro, and the obtained structure parameters are strongly related to those obtained by μCT. A fair CNR and strong correlations can be obtained with a low radiation dose, indicating the possibility for monitoring trabecular bone structure also in vivo. PMID:25168811

  15. Vibrational mid-infrared photothermal spectroscopy using a fiber laser probe: asymptotic limit in signal-to-baseline contrast.

    PubMed

    Totachawattana, Atcha; Liu, Hui; Mertiri, Alket; Hong, Mi K; Erramilli, Shyamsunder; Sander, Michelle Y

    2016-01-01

    We report on a mid-infrared photothermal spectroscopy system with a near-infrared fiber probe laser and a tunable quantum cascade pump laser. Photothermal spectra of a 6 μm-thick 4-octyl-4'-cyanobiphenyl liquid crystal sample are measured with a signal-to-baseline contrast above 103. As both the peak photothermal signal and the corresponding baseline increase linearly with probe power, the signal-to-baseline contrast converges to an asymptotic limit for a given pump power. This limit is independent of the probe power and characterizes the best contrast achievable for the system. This enables sensitive quantitative spectral characterization of linear infrared absorption features directly from photothermal spectroscopy measurements. PMID:26696188

  16. Stable oxygen and hydrogen isotopes of brines - comparing isotope ratio mass spectrometry and isotope ratio infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Ahrens, Christian; Koeniger, Paul; van Geldern, Robert; Stadler, Susanne

    2013-04-01

    Today's standard analytical methods for high precision stable isotope analysis of fluids are gas-water equilibration and high temperature pyrolysis coupled to isotope ratio mass spectrometers (IRMS). In recent years, relatively new laser-based analytical instruments entered the market that are said to allow high isotope precision data on nearly every media. This optical technique is referred to as isotope ratio infrared spectroscopy (IRIS). The objective of this study is to evaluate the capability of this new instrument type for highly saline solutions and a comparison of the analytical results with traditional IRMS analysis. It has been shown for the equilibration method that the presence of salts influences the measured isotope values depending on the salt concentration (see Lécuyer et al, 2009; Martineau, 2012). This so-called 'isotope salt effect' depends on the salt type and salt concentration. These factors change the activity in the fluid and therefore shift the isotope ratios measured by the equilibration method. Consequently, correction factors have to be applied to these analytical data. Direct conversion techniques like pyrolysis or the new laser instruments allow the measurement of the water molecule from the sample directly and should therefore not suffer from the salt effect, i.e. no corrections of raw values are necessary. However, due to high salt concentrations this might cause technical problems with the analytical hardware and may require labor-intensive sample preparation (e.g. vacuum distillation). This study evaluates the salt isotope effect for the IRMS equilibration technique (Thermo Gasbench II coupled to Delta Plus XP) and the laser-based IRIS instruments with liquid injection (Picarro L2120-i). Synthetic salt solutions (NaCl, KCl, CaCl2, MgCl2, MgSO4, CaSO4) and natural brines collected from the Stassfurt Salt Anticline (Germany; Stadler et al., 2012) were analysed with both techniques. Salt concentrations ranged from seawater salinity

  17. CONSTRAINING MASS RATIO AND EXTINCTION IN THE FU ORIONIS BINARY SYSTEM WITH INFRARED INTEGRAL FIELD SPECTROSCOPY

    SciTech Connect

    Pueyo, Laurent; Hillenbrand, Lynne; Hinkley, Sasha; Dekany, Richard; Roberts, Jenny; Vasisht, Gautam; Roberts, Lewis C. Jr.; Shao, Mike; Burruss, Rick; Cady, Eric; Oppenheimer, Ben R.; Brenner, Douglas; Zimmerman, Neil; Monnier, John D.; Crepp, Justin; Parry, Ian; Beichman, Charles; Soummer, Remi

    2012-09-20

    We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0.''5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 {mu}m interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, A{sub V} = 8-12, with an effective temperature of {approx}4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

  18. Constraining Mass Ratio and Extinction in the FU Orionis Binary System with Infrared Integral Field Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pueyo, Laurent; Hillenbrand, Lynne; Vasisht, Gautam; Oppenheimer, Ben R.; Monnier, John D.; Hinkley, Sasha; Crepp, Justin; Roberts, Lewis C., Jr.; Brenner, Douglas; Zimmerman, Neil; Parry, Ian; Beichman, Charles; Dekany, Richard; Shao, Mike; Burruss, Rick; Cady, Eric; Roberts, Jenny; Soummer, Rémi

    2012-09-01

    We report low-resolution near-infrared spectroscopic observations of the eruptive star FU Orionis using the Integral Field Spectrograph (IFS) Project 1640 installed at the Palomar Hale telescope. This work focuses on elucidating the nature of the faint source, located 0farcs5 south of FU Ori, and identified in 2003 as FU Ori S. We first use our observations in conjunction with published data to demonstrate that the two stars are indeed physically associated and form a true binary pair. We then proceed to extract J- and H-band spectro-photometry using the damped LOCI algorithm, a reduction method tailored for high contrast science with IFS. This is the first communication reporting the high accuracy of this technique, pioneered by the Project 1640 team, on a faint astronomical source. We use our low-resolution near-infrared spectrum in conjunction with 10.2 μm interferometric data to constrain the infrared excess of FU Ori S. We then focus on estimating the bulk physical properties of FU Ori S. Our models lead to estimates of an object heavily reddened, AV = 8-12, with an effective temperature of ~4000-6500 K. Finally, we put these results in the context of the FU Ori N-S system and argue that our analysis provides evidence that FU Ori S might be the more massive component of this binary system.

  19. Crimson carrier, a long-acting contrast agent for in vivo near-infrared imaging of injured and diseased muscle.

    PubMed

    Prajapati, Suresh I; Martinez, Carlo O; Abraham, Jinu; McCleish, Amanda T; Michalek, Joel E; McManus, Linda M; Rubin, Brian P; Shireman, Paula K; Keller, Charles

    2010-08-01

    The near-infrared wavelengths (700-900 nm) are the most suitable optical window for light penetration and deep tissue imaging in small animals. Herein we report a near-infrared fluorescent contrast agent, crimson carrier, which acts as a blood pool contrast agent to detect and quantify injury and disease in live animals. After determining the excitation-emission spectra and pharmacokinetics, crimson carrier was injected into myoinjured mice to monitor their recovery. Crimson carrier was also used to image transgenic mice with spontaneous tumors. Crimson carrier has maximal excitation and emission wavelengths of 745 nm and 820 nm, respectively. Elimination occurs predominantly via urinary excretion. We demonstrate the utility of this contrast agent for serial imaging of traumatized muscle as well as muscle tumors. The unique long-acting pharmacokinetics and urinary excretion route characteristics make crimson carrier a contrast agent of choice for the visualization of tumors and injured muscle or other tissues in live animal studies. PMID:20544935

  20. Development and Airborne Operation of a Compact Water Isotope Ratio Infrared Spectrometer

    NASA Technical Reports Server (NTRS)

    Iannone, Rosario Q.; Kassi, Samir; Jost, Hans-Juerg; Chenevier, Marc; Romanini, Daniele; Meijer, Harro A. J.; Dhaniyala, Suresh; Snels, Marcel; Kerstel, Erik R. T.

    2009-01-01

    A sensitive laser spectrometer, named IRIS (water isotope ratio infrared spectrometer), was developed for the in situ detection of the isotopic composition of water vapour in the upper troposphere and the lower stratosphere. Isotope ratio measurements can be used to quantify troposphere stratosphere exchange, and to study the water chemistry in the stratosphere. IRIS is based on the technique of optical feedback cavity-enhanced absorption spectroscopy. It uses a room temperature near-infrared laser, and does not require cryogenic cooling of laser or detectors. The instrument weighs 51 kg including its support structure. Airborne operation was demonstrated during three flights aboard the European M55-Geophysica stratospheric research aircraft, as part of the AMMA/SCOUT-03 (African Monsoon Multidisciplinary Analysis/Stratospheric Climate links with emphasis on the Upper Troposphere and lower stratosphere) campaign in Burkina Faso in August 2006. The data are discussed with reference to a Rayleigh distillation model. As expected, there is no indication of non-mass-dependent fractionation (also known as mass-independent fractionation) in the troposphere. Furthermore, improvements to the thermal management system and a move to a (cryogen-free) longer-wavelength laser source are discussed, which together should result in approximately two orders of magnitude improvement of the sensitivity

  1. Experimental evaluation of a hyperspectral imager for near-infrared fluorescent contrast agent studies

    NASA Astrophysics Data System (ADS)

    Luthman, A. S.; Bohndiek, Sarah E.

    2015-03-01

    Hyperspectral imaging (HSI) systems have the potential to combine morphological and spectral information to provide detailed and high sensitivity readouts in biological and medical applications. As HSI enables simultaneous detection in several spectral bands, the technology has significant potential for use in real-time multiplexed contrast agent studies. Examples include tumor detection in intraoperative and endoscopic imaging as well as histopathology. A multiplexed readout from multiple disease targets, such as cell surface receptors overexpressed in cancer cells, could improve both sensitivity and specificity of tumor identification. Here, we evaluate a commercial, compact, near-infrared HSI sensor that has the potential to enable low cost, video rate HSI for multiplexed fluorescent contrast agent studies in biomedical applications. The hyperspectral imager, based on a monolithically integrated Fabry-Perot etalon, has 70 spectral bands between 600-900 nm, making it ideal for this application. Initial calibration of the imager was performed to determine wavelength band response, quantum efficiency and the effect of F-number on the spectral response. A platform for wide-field fluorescence imaging in reflectance using fluorophore specific LED excitation was then developed. The applicability of the imaging platform for simultaneous readout of multiple fluorophore signals was demonstrated using a dilution series of Alexa Fluor 594 and Alexa Fluor 647, showing that nanomolar fluorophore concentrations can be detected. Our results show that the HSI system can clearly resolve the emission spectra of the two fluorophores in mixtures of concentrations across several orders of magnitude, indicating a high dynamic range performance. We therefore conclude that the HSI sensor tested here is suitable for detecting fluorescence in biomedical imaging applications.

  2. Analytical techniques in biomedical stable isotope applications: (isotope ratio) mass spectrometry or infrared spectrometry?

    PubMed

    Stellaard, Frans; Elzinga, Henk

    2005-12-01

    An overview is presented of biomedical applications of stable isotopes in general, but mainly focused on the activities of the Center for Liver, Digestive and Metabolic Diseases of the University Medical Center Groningen. The aims of metabolic studies in the areas of glucose, fat, cholesterol and protein metabolism are briefly explained, as well as the principle of breath testing and the techniques to study body composition and energy expenditure. Much attention is paid to the analytical considerations based upon metabolite concentrations, sample size restrictions, the availability of stable isotope labelled substrates and dose requirements in relation to compound-specific isotope analysis. The instrumental advantages and limitations of the generally used techniques gas chromatography/reaction/isotope ratio mass spectrometry and gas chromatography/mass spectrometry are described as well as the novelties of the recently commercialised liquid chromatography/combustion/isotope ratio mass spectrometry. The present use and future perspective of infrared (IR) spectrometry for clinical and biomedical stable isotope applications are reviewed. In this respect, the analytical demands on IR spectrometry are discussed to enable replacement of isotope ratio mass spectrometry by IR spectrometry, in particular, for the purpose of compound-specific isotope ratio analysis in biological matrices. PMID:16543190

  3. Land surface phenologies viewed in the middle infrared: seasonal contrasts between vegetation, soils, and impervious surfaces

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.; Krehbiel, C.; Kovalskyy, V.

    2012-12-01

    The middle infrared (MIR) region of the electromagnetic spectrum spans 3-5 microns. It is the mixing zone between reflected sunlight and emitted earthlight in roughly equal proportions. This region has received very little attention in terrestrial remote sensing. Yet the MIR merits exploration of how it could be used for monitoring land surface phenologies (LSP) and seasonalities due to five characteristics. First, green vegetation is MIR-dark, reflecting just 2-5% of the incident radiation. Second, soils are MIR-bright, reflecting up to one-third of the incident radiation. Third, impervious surfaces, such as concretes, asphalts, and other building and paving materials are also MIR-bright. Fourth, the resulting seasonal contrast in MIR between vegetated and non-vegetated surfaces lets urbanized areas emerge from the vegetated landscape. Fifth, MIR wavelengths penetrate anthropogenic haze and smoke because the particle radii are smaller. Here we use MODIS (MYD02) image time series to illustrate the temporal progressions of MIR at various wavelengths and how they compare to and diverge from the more familiar NDVI and derived LSP metrics.IR portrait of the USA east of W98: maximum value composite of Aqua MODIS MIR band 23 during DOY 219-233 of 2010.

  4. A multiscale contrast direction adaptation approach for the fusion of multispectral and multifocus infrared images

    NASA Astrophysics Data System (ADS)

    Karali, A. O.; Cakir, Serdar; Aytaç, Tayfun

    2015-10-01

    Infrared (IR) cameras are widely used in latest surveillance systems because spectral characteristics of objects provide valuable information for object detection and identification. To assist the surveillance system operator and automatic image processing tasks, fusing images in IR band is proposed as a solution to increase situational awareness and different fusion techniques are developed for this purpose. Proposed techniques are generally developed for specific scenarios because image content may vary dramatically depending on the spectral range, the optical properties of the cameras, the spectral characteristics of the scene, and the spatial resolution of the interested targets in the scene. A general purpose IR image fusion technique that is suitable for real-time applications is proposed. The proposed technique can support different scenarios by applying a multiscale detail detection and can be applied to images captured from different spectral regions of the spectrum by adaptively adjusting the contrast direction through cross checking between the source images. The feasibility of the proposed algorithm is demonstrated on registered multi-spectral and multi-focus IR images. Fusion results are presented and the performance of the proposed technique is compared with the baseline fusion methods through objective and subjective tests. The technique outperforms baseline methods in the subjective tests and provide promising results in objective quality metrics with an acceptable computational load. Besides, the proposed technique preserves object details and prevents undesired artifacts better than the baseline techniques in the image fusion scenario that contains four source images.

  5. Infrared differential interference contrast microscopy for overlay metrology on 3D-interconnect bonded wafers

    NASA Astrophysics Data System (ADS)

    Ku, Yi-sha; Shyu, Deh-Ming; Lin, Yeou-Sung; Cho, Chia-Hung

    2013-04-01

    Overlay metrology for stacked layers will be playing a key role in bringing 3D IC devices into manufacturing. However, such bonded wafer pairs present a metrology challenge for optical microscopy tools by the opaque nature of silicon. Using infrared microscopy, silicon wafers become transparent to the near-infrared (NIR) wavelengths of the electromagnetic spectrum, enabling metrology at the interface of bonded wafer pairs. Wafers can be bonded face to face (F2F) or face to back (F2B) which the stacking direction is dictated by how the stacks are carried in the process and functionality required. For example, Memory stacks tend to use F2B stacking enables a better managed design. Current commercial tools use single image technique for F2F bonding overlay measurement because depth of focus is sufficient to include both surfaces; and use multiple image techniques for F2B overlay measurement application for the depth of focus is no longer sufficient to include both stacked wafer surfaces. There is a need to specify the Z coordinate or stacking wafer number through the silicon when visiting measurement wafer sites. Two shown images are of the same (X, Y) but separate Z location acquired at focus position of each wafer surface containing overlay marks. Usually the top surface image is bright and clear; however, the bottom surface image is somewhat darker and noisier as an adhesive layer is used in between to bond the silicon wafers. Thus the top and bottom surface images are further processed to achieve similar brightness and noise level before merged for overlay measurement. This paper presents a special overlay measurement technique, using the infrared differential interference contrast (DIC) microscopy technique to measure the F2B wafer bonding overlay by a single shot image. A pair of thinned wafers at 50 and 150 μm thickness is bonded on top of a carrier wafer to evaluate the bonding overlay. It works on the principle of interferometry to gain information about the

  6. A Widely Tunable Infrared Laser Spectrometer for Measurements of Isotopic Ratios of Carbon Cycle Gases

    SciTech Connect

    Joanne H. Shorter; J. Barry McManus; David D. Nelson; Charles E. Kolb; Mark S. Zahniser; Ray Bambha; Uwe Lehmann; Tomas Kulp; Stanley C. Tyler

    2005-01-31

    The atmospheric abundances of carbon dioxide and methane have increased dramatically during the industrial era. Measurements of the isotopic composition of these gases can provide a powerful tool for quantifying their sources and sinks. This report describes the development of a portable instrument for isotopic analysis CO{sub 2} and CH{sub 4} using tunable infrared laser absorption spectroscopy. This instrument combines novel optical design and signal processing methods with a widely tunable mid-infrared laser source based on difference frequency generation (DFG) which will can access spectral regions for all the isotopes of CO{sub 2} and CH{sub 4} with a single instrument. The instrument design compensates for the large difference in concentration between major and minor isotopes by measuring them with path lengths which differ by a factor of 100 within the same multipass cell. During Phase I we demonstrated the basic optical design and signal processing by determining {sup 13}CO{sub 2} isotopic ratios with precisions as small as 0.2{per_thousand} using a conventional lead salt diode laser. During Phase II, the DFG laser source was coupled with the optical instrument and was demonstrated to detect {sup 13}CH{sub 4}/{sup 12}CH{sub 4} ratios with a precision of 0.5{per_thousand} and an averaging time of 20 s using concentrated methane in air with a mixing ratio of 2700 ppm. Methods for concentrating ambient air for isotopic analysis using this technique have been evaluated. Extensions of this instrument to other species such as {sup 13}CO{sub 2}, C{sup 18}OO, and CH{sub 3}D are possible by substituting lasers at other wavelengths in the DFG source module. The immediate commercial application of this instrument will be to compete with existing mass spectrometric isotope instruments which are expensive, large and relatively slow. The novel infrared source developed in this project can be applied to the measurement of many other gas species and will have wide

  7. Mid-infrared-selected Quasars. I. Virial Black Hole Mass and Eddington Ratios

    NASA Astrophysics Data System (ADS)

    Dai, Y. Sophia; Elvis, Martin; Bergeron, Jacqueline; Fazio, Giovanni G.; Huang, Jia-Sheng; Wilkes, Belinda J.; Willmer, Christopher N. A.; Omont, Alain; Papovich, Casey

    2014-08-01

    We provide a catalog of 391 mid-infrared-selected (MIR; 24 μm) broad-emission-line (BEL; type 1) quasars in the 22 deg2 SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S 24 > 400 μJy, jointly with an optical magnitude limit of r (AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ~ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  8. Mid-infrared-selected quasars. I. Virial black hole mass and eddington ratios

    SciTech Connect

    Dai, Y. Sophia; Elvis, Martin; Fazio, Giovanni G.; Huang, Jia-Sheng; Wilkes, Belinda J.; Bergeron, Jacqueline; Omont, Alain; Willmer, Christopher N. A.; Papovich, Casey

    2014-08-20

    We provide a catalog of 391 mid-infrared-selected (MIR; 24 μm) broad-emission-line (BEL; type 1) quasars in the 22 deg{sup 2} SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with S {sub 24} > 400 μJy, jointly with an optical magnitude limit of r (AB) < 22.5 for broad line identification. The catalog is based on MMT and Sloan Digital Sky Survey (SDSS) spectroscopy to select BEL quasars, extending the SDSS coverage to fainter magnitudes and lower redshifts, and recovers a more complete quasar population. The MIR-selected quasar sample peaks at z ∼ 1.4 and recovers a significant and constant (20%) fraction of extended objects with SDSS photometry across magnitudes, which were not included in the SDSS quasar survey dominated by point sources. This sample also recovers a significant population of z < 3 quasars at i > 19.1. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The supermassive black hole mass shows evidence of downsizing, although the Eddington ratios remain constant at 1 < z < 4. Compared to point sources in the same redshift range, extended sources at z < 1 show systematically lower Eddington ratios. The catalog and spectra are publicly available online.

  9. Methods and Systems for Measurement and Estimation of Normalized Contrast in Infrared Thermography

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay M. (Inventor)

    2015-01-01

    Methods and systems for converting an image contrast evolution of an object to a temperature contrast evolution and vice versa are disclosed, including methods for assessing an emissivity of the object; calculating an afterglow heat flux evolution; calculating a measurement region of interest temperature change; calculating a reference region of interest temperature change; calculating a reflection temperature change; calculating the image contrast evolution or the temperature contrast evolution; and converting the image contrast evolution to the temperature contrast evolution or vice versa, respectively.

  10. Improved collision strengths and line ratios for forbidden [O III] far-infrared and optical lines

    NASA Astrophysics Data System (ADS)

    Palay, Ethan; Nahar, Sultana N.; Pradhan, Anil K.; Eissner, Werner

    2012-06-01

    Far-infrared and optical [O III] lines are useful temperature-density diagnostics of nebular as well as dust obscured astrophysical sources. Fine-structure transitions among the ground state levels 1 s22 s22 p33 P 0,1,2 give rise to the 52- and 88-?m lines, whereas transitions among the 3 P 0,1,2, 1 D 2, 1 S 0 levels yield the well-known optical lines λλ4363, 4959 and 5007 Å. These lines are excited primarily by electron impact excitation. However, despite their importance in nebular diagnostics collision strengths for the associated fine-structure transitions have not been computed taking full account of relativistic effects. We present Breit-Pauli R-matrix calculations for the collision strengths with highly resolved resonance structures. We find significant differences of up to 20 per cent in the Maxwellian averaged rate coefficients from previous works. We also tabulate these to lower temperatures down to 100 K to enable determination of physical conditions in cold dusty environments such photodissociation regions and ultraluminous infrared galaxies observed with the Herschel Space Observatory. We also examine the effect of improved collision strengths on temperature- and density-sensitive line ratios.

  11. Time-resolved spectroscopy and near infrared imaging enhanced by receptor-targeted contrast agents for prostate cancer detection

    NASA Astrophysics Data System (ADS)

    Pu, Y.; Wang, W. B.; Tang, G. C.; Achilefu, S.; Alfano, R. R.

    2011-03-01

    Time-resolved spectroscopy and near infrared imaging enhanced by receptor-targeted contrast agents for prostate cancer detection will be presented. Two contrast agents, Cybesin and Cytate, were investigated using time-resolved spectroscopy in aqueous solution and cancerous and normal prostate tissues. The time evolution of the fluorescent dipole in solution was studied using a system of first-order linear differential equations containing two main parameters: the decay rate of emission and the rate of one orthogonal emission component transferring to another. An analytical polarization model was developed and used to extract rotational times and fluorescence anisotropies of the contrast agents in prostate tissues. The differences of rotational times and polarization anisotropies were observed for Cybesin (Cytate) in cancerous and normal prostate tissue, which reflect preferred bond of contrast agents and cancerous tissue cells. The conjugation of Cybesin (Cytate) to prostate cancerous cells offers high contrast between normal and cancerous tissues.

  12. High Contrast In vitro and In vivo Photoluminescence Bioimaging Using Near Infrared to Near Infrared Up-Conversion in Tm3+ and Yb3+ Doped Fluoride Nanophosphors

    PubMed Central

    Nyk, Marcin; Kumar, Rajiv; Ohulchanskyy, Tymish Y.; Bergey, Earl J.; Prasad, Paras N.

    2012-01-01

    A new approach for photoluminescence imaging in vitro and in vivo has been shown, utilizing near infrared to near infrared (NIR-to-NIR) up-conversion in nanophosphors. This NIR-to-NIR up-conversion process provides deeper light penetration into biological specimen and results in high contrast optical imaging due to absence of an autofluorescence background and decreased light scattering. Aqueous dispersible fluoride (NaYF4) nanocrystals (20–30 nm size) co-doped with the rare earth ions, Tm3+ and Yb3+, were synthesized and characterized by TEM, XRD and photoluminescence (PL) spectroscopy. In vitro cellular uptake was shown by the PL microscopy visualizing the characteristic emission of Tm3+ at ~ 800 nm excited with 975 nm. No apparent cytotoxicity was observed. Subsequent animal imaging studies were performed using Balb-c mice injected intravenously with up-converting nanophosphors, demonstrating the high contrast PL imaging in vivo. PMID:18928324

  13. Development and airborne operation of a compact water isotope ratio infrared spectrometer.

    PubMed

    Iannone, Rosario Q; Kassi, Samir; Jost, Hans-Jürg; Chenevier, Marc; Romanini, Daniele; Meijer, Harro A J; Dhaniyala, Suresh; Snels, Marcel; Kerstel, Erik R T

    2009-12-01

    A sensitive laser spectrometer, named IRIS (water isotope ratio infrared spectrometer), was developed for the in situ detection of the isotopic composition of water vapour in the upper troposphere and the lower stratosphere. Isotope ratio measurements can be used to quantify troposphere-stratosphere exchange, and to study the water chemistry in the stratosphere. IRIS is based on the technique of optical feedback cavity-enhanced absorption spectroscopy. It uses a room temperature near-infrared laser, and does not require cryogenic cooling of laser or detectors. The instrument weighs 51 kg including its support structure. Airborne operation was demonstrated during three flights aboard the European M55-Geophysica stratospheric research aircraft, as part of the AMMA/SCOUT-03 (African Monsoon Multidisciplinary Analysis/Stratospheric Climate links with emphasis on the Upper Troposphere and lower stratosphere) campaign in Burkina Faso in August 2006. One-second averaged, vertical profiles of delta(2)H, delta(17)O and delta(18)O in the upper troposphere are shown, as are the delta(17)O-delta(18)O and delta(2)H-delta(18)O relations. The data are discussed with reference to a Rayleigh distillation model. As expected, there is no indication of non-mass-dependent fractionation (also known as mass-independent fractionation) in the troposphere. Furthermore, improvements to the thermal management system and a move to a (cryogen-free) longer-wavelength laser source are discussed, which together should result in approximately two orders of magnitude improvement of the sensitivity. PMID:19670069

  14. Search for novel contrast materials in dual-energy x-ray breast imaging using theoretical modeling of contrast-to-noise ratio

    NASA Astrophysics Data System (ADS)

    Karunamuni, R.; Maidment, A. D. A.

    2014-08-01

    Contrast-enhanced (CE) dual-energy (DE) x-ray breast imaging uses a low- and high-energy x-ray spectral pair to eliminate soft-tissue signal variation and thereby increase the detectability of exogenous imaging agents. Currently, CEDE breast imaging is performed with iodinated contrast agents. These compounds are limited by several deficiencies, including rapid clearance and poor tumor targeting ability. The purpose of this work is to identify novel contrast materials whose contrast-to-noise ratio (CNR) is comparable or superior to that of iodine in the mammographic energy range. A monoenergetic DE subtraction framework was developed to calculate the DE signal intensity resulting from the logarithmic subtraction of the low- and high-energy signal intensities. A weighting factor is calculated to remove the dependence of the DE signal on the glandularity of the breast tissue. Using the DE signal intensity and weighting factor, the CNR for materials with atomic numbers (Z) ranging from 1 to 79 are computed for energy pairs between 10 and 50 keV. A group of materials with atomic numbers ranging from 42 to 63 were identified to exhibit the highest levels of CNR in the mammographic energy range. Several of these materials have been formulated as nanoparticles for various applications but none, apart from iodine, have been investigated as CEDE breast imaging agents. Within this group of materials, the necessary dose fraction to the LE image decreases as the atomic number increases. By reducing the dose to the LE image, the DE subtraction technique will not provide an anatomical image of sufficient quality to accompany the contrast information. Therefore, materials with Z from 42 to 52 provide nearly optimal values of CNR with energy pairs and dose fractions that provide good anatomical images. This work is intended to inspire further research into new materials for optimized CEDE breast functional imaging.

  15. Hafnia (HfO2) nanoparticles as an X-ray contrast agent and mid-infrared biosensor.

    PubMed

    McGinnity, Tracie L; Dominguez, Owen; Curtis, Tyler E; Nallathamby, Prakash D; Hoffman, Anthony J; Roeder, Ryan K

    2016-07-14

    The interaction of hafnium oxide (HfO2) nanoparticles (NPs) with X-ray and mid-infrared radiation was investigated to assess the potential as a multifunctional diagnostic probe for X-ray computed tomography (CT) and/or mid-infrared biosensing. HfO2 NPs of controlled size were prepared by a sol-gel process and surface functionalized with polyvinylpyrrolidone, resulting in relatively spherical and monodispersed NPs with a tunable mean diameter in the range of ∼7-31 nm. The X-ray attenuation of HfO2 NPs was measured over 0.5-50 mM concentration and compared with Au NPs and iodine, which are the most prominent X-ray contrast agents currently used in research and clinical diagnostic imaging, respectively. At clinical CT tube potentials >80 kVp, HfO2 NPs exhibited superior or similar X-ray contrast compared to Au NPs, while both exhibited significantly greater X-ray contrast compared to iodine, due to the favorable location of the k-shell absorption edge for hafnium and gold. Moreover, energy-dependent differences in X-ray attenuation enabled simultaneous quantitative molecular imaging of each agent using photon-counting spectral (multi-energy) CT. HfO2 NPs also exhibited a strong mid-infrared absorption in the Reststrahlen band from ∼250-800 cm(-1) and negative permittivity below 695 cm(-1), which can enable development of mid-infrared biosensors and contrast agents, leveraging surface enhanced mid-infrared and/or phonon polariton absorption. PMID:27364973

  16. Hafnia (HfO2) nanoparticles as an X-ray contrast agent and mid-infrared biosensor

    NASA Astrophysics Data System (ADS)

    McGinnity, Tracie L.; Dominguez, Owen; Curtis, Tyler E.; Nallathamby, Prakash D.; Hoffman, Anthony J.; Roeder, Ryan K.

    2016-07-01

    The interaction of hafnium oxide (HfO2) nanoparticles (NPs) with X-ray and mid-infrared radiation was investigated to assess the potential as a multifunctional diagnostic probe for X-ray computed tomography (CT) and/or mid-infrared biosensing. HfO2 NPs of controlled size were prepared by a sol-gel process and surface functionalized with polyvinylpyrrolidone, resulting in relatively spherical and monodispersed NPs with a tunable mean diameter in the range of ~7-31 nm. The X-ray attenuation of HfO2 NPs was measured over 0.5-50 mM concentration and compared with Au NPs and iodine, which are the most prominent X-ray contrast agents currently used in research and clinical diagnostic imaging, respectively. At clinical CT tube potentials >80 kVp, HfO2 NPs exhibited superior or similar X-ray contrast compared to Au NPs, while both exhibited significantly greater X-ray contrast compared to iodine, due to the favorable location of the k-shell absorption edge for hafnium and gold. Moreover, energy-dependent differences in X-ray attenuation enabled simultaneous quantitative molecular imaging of each agent using photon-counting spectral (multi-energy) CT. HfO2 NPs also exhibited a strong mid-infrared absorption in the Reststrahlen band from ~250-800 cm-1 and negative permittivity below 695 cm-1, which can enable development of mid-infrared biosensors and contrast agents, leveraging surface enhanced mid-infrared and/or phonon polariton absorption.

  17. Isotope-ratio infrared spectroscopy: a reliable tool for the investigation of plant-water sources?

    PubMed

    Martín-Gómez, Paula; Barbeta, Adrià; Voltas, Jordi; Peñuelas, Josep; Dennis, Kate; Palacio, Sara; Dawson, Todd E; Ferrio, Juan Pedro

    2015-08-01

    Stable isotopes are extensively used as tracers for the study of plant-water sources. Isotope-ratio infrared spectroscopy (IRIS) offers a cheaper alternative to isotope-ratio mass spectroscopy (IRMS), but its use in studying plant and soil water is limited by the spectral interference caused by organic contaminants. Here, we examine two approaches to cope with contaminated samples in IRIS: on-line oxidation of organic compounds (MCM) and post-processing correction. We assessed these methods compared to IRMS across 136 samples of xylem and soil water, and a set of ethanol- and methanol-water mixtures. A post-processing correction significantly improved IRIS accuracy in both natural samples and alcohol dilutions, being effective with concentrations up to 8% of ethanol and 0.4% of methanol. MCM outperformed the post-processing correction in removing methanol interference, but did not effectively remove interference for high concentrations of ethanol. By using both approaches, IRIS can overcome with reasonable accuracy the analytical uncertainties associated with most organic contaminants found in soil and xylem water. We recommend the post-processing correction as the first choice for analysis of samples of unknown contamination. Nevertheless, MCM can be more effective for evaluating samples containing contaminants responsible for strong spectral interferences at low concentrations, such as methanol. PMID:25790288

  18. FE-XIII Infrared / FE-XIV Green Line Ratio Diagnostics (P55)

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; et al.

    2006-11-01

    aks.astro.itbhu@gmail.com We consider the first 27-level atomic model of Fe XIII (5.9 < log Te < 6.4 K) to estimate its ground level populations, taking account of electron as well as proton collisional excitations and de-excitations, radiative cascades, radiative excitations and de-excitations. Radiative cascade is important but the effect of dilution factor is negligible at higher electron densities. The 3 P1-3P0 and 3P2-3P1 transitions in the ground configuration 3s2 3p2 of Fe XIII result in two forbidden coronal emission lines in the infrared region, namely 10747 Å and 10798 Å., while the 5303 Å green line is formed in the 3s2 3p 2 2 ground configuration of Fe XIV as a result of P3 / 2 - P1 / 2 magnetic dipole transition. The line-widths of appropriate pair of forbidden coronal emission lines observed simultaneously can be useful diagnostic tool to deduce temperature and non-thermal velocity in the large scale coronal structures using intensity ratios of the lines as the temperature signature, instead of assuming ion temperature to be equal to the electron temperature. Since the line intensity ratios IG5303/IIR10747 and IG5303/IIR10798 have very week density dependence, they are ideal monitors of temperature mapping in the solar corona.

  19. A far-infrared study of N/O abundance ratio in galactic H 2 regions

    NASA Technical Reports Server (NTRS)

    Lester, D. F.; Dinerstein, H. L.; Werner, M. W.; Watson, D. M.; Genzel, R. L.

    1983-01-01

    Far-infrared lines of N++ and O++ in several galactic H II regions were measured in an effort to probe the abundance ratio N/O. New measurements are presented for W32 (630.8-0.0), Orion A, and G75.84+0.4. The combination of (N III) 57.3 millimicrons and (O III) 88.4 and 51.8 millimicrons yields measurements of N++/O++ that are largely insensitive to electron temperature, density uncertainties, and to clumping of the ionized gas, due to the similarity of the critical densities for these transitions. In the observed nebulae, N++/O++ should be indicative of N/O, a ratio that is of special importance in nucleosynthesis theory. Measurements are compared with previous measurements of M17 and W51. For nebulae in the solar circle, N++/O++ is greater than the N/O values derived from optical studies of N+/O+ in low ionization zones of the same nebulae. We find that N++/O++ in W43 is significantly higher than for the other H II regions in the sample. Since W43 is located at R = 5 kpc, which is the smallest galactocentric distance in our sample, our data appear consistent with the presence of a negative abundance gradient d(N/O)dR.

  20. On-site isotopic analysis of dissolved inorganic carbon using an isotope ratio infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Stoltmann, Tim; Mandic, Magda; Stöbener, Nils; Wapelhorst, Eric; Aepfler, Rebecca; Hinrichs, Kai-Uwe; Taubner, Heidi; Jost, Hj; Elvert, Marcus

    2016-04-01

    An Isotope Ratio Infrared Spectrometer (IRIS) has been adapted to perform measurements of δ13C of dissolved inorganic carbon (DIC) in marine pore waters. The resulting prototype allowed highly automated analysis of δ13C isotopic ratios and CO2 concentration. We achieved a throughput of up to 70 samples per day with DIC contents as low as 1.7 μmol C. We achieved an internal precision of 0.066 ‰ and an external precision of 0.16 ‰, which is comparable to values given for Isotope Ratio Mass Spectrometers (IRMS). The prototype instrument is field deployable, suitable for shipboard analysis of deep sea core pore waters. However, the validation of the prototype was centered around a field campaign in Eckernförde Bay, NW- Baltic Sea. As a proof of concept, a shallow site within an area of submarine groundwater discharge (SGD) and a site outside this area was investigated. We present profiles of δ13C of DIC over 50 cm exhibiting well understood methane turnover processes (anaerobic oxidation of methane). At the lowest point below the seafloor, microbial reduction of CO2 to CH4 dominates. 12CO2 is reduced preferentially over 13CO2, leading to more positive δ13C values in the remaining DIC pool; in layers closer to the surface, the oxidation of CH4 to CO2 becomes more prominent. Since the CH4 pool is enriched in 12C a shift to more negative δ13C can be observed in the DIC pool. In the upper 15 cm, the pore water DIC mixes with the sea water DIC, increasing δ13C again. Finally, we will present recent developments to further improve performance and future plans for deployments on research cruises.

  1. High-Contrast Near-Infrared Imaging and Modeling of Planets and Debris Disks

    NASA Astrophysics Data System (ADS)

    Rodigas, Timothy; Hinz, P.; Weinberger, A. J.; Close, L. M.; Debes, J. H.

    2014-01-01

    Planets are thought to form in circumstellar disks, leaving behind planetesimals that collide to produce dusty debris disks. Characterizing the architectures of planetary systems, along with the structures and compositions of debris disks, can therefore help answer questions about how planets form. In this talk, I will present the results of five papers concerning the properties of extrasolar planetary systems and their circumstellar environments. First I will discuss bias affecting radial velocity (RV) orbital eccentricity. For years astronomers have been puzzled about the large number of RV-detected planets that have eccentric orbits (e > 0.1). I will show that this problem can partially be explained by showing that two circular-orbit planets can masquerade as a single planet on an eccentric orbit. I use this finding to predict that planets with mildly eccentric orbits are the most likely to have massive companions on wide orbits, potentially detectable by future direct imaging observations. Next I will present recent high-contrast 2-4 μm imaging studies of the edge-on debris disks around HD 15115 and HD 32297. HD 15115’s color is found to be gray, implying large grains 1-10 μm in size reside in stable orbits in the disk. HD 32297’s disk color is red from 1-4 μm. Cometary material (carbon, silicates, and porous water ice) are a good match at 1-2 μm but not at L‧. Tholins, organic material that is found in outer solar system bodies, or small silicates can explain the disk’s red color but not the short wavelength data. I will then present my work on the dynamics of dust grains in the presence of massive planets. I will show that the width of a debris disk increases proportionally with the mass of its shepherding planet. I use this result to make predictions for the masses and orbits of putative planets in five well-known disks. Finally, I will present recent MagAO/Clio near-infrared imaging results on the debris disk around HR4796A spanning the 0.5-4 um

  2. Optimization of contrast-to-tissue ratio through pulse windowing in dual-frequency “acoustic angiography” imaging

    PubMed Central

    Lindsey, Brooks D.; Shelton, Sarah E.; Dayton, Paul A.

    2016-01-01

    Early-stage tumors in many cancers are characterized by vascular remodeling, indicative of transformations in cell function. We have previously presented a high-resolution ultrasound imaging approach for detecting these changes which is based on microbubble contrast agents. In this technique, images are formed from only the higher harmonics of microbubble contrast agents, producing images of vasculature alone with 100–200 μm resolution. In this article, shaped transmit pulses are applied to imaging the higher broadband harmonic echoes of microbubble contrast agents, and the effects of varying pulse window and phasing on microbubble and tissue harmonic echoes are evaluated using a dual-frequency transducer in vitro and in vivo. An increase in contrast-to-tissue ratio of 6.8 ± 2.3 dB was observed in vitro by using an inverted pulse with a cosine window relative to a non-inverted pulse with a rectangular window. The increase in mean image intensity due to contrast enhancement in vivo in five rodents was 13.9 ± 3.0 dB greater for an inverted cosine-windowed pulse and 17.8 ± 3.6 dB greater for a non-inverted Gaussian-windowed relative to a non-inverted pulse with a rectangular window. Implications for pre-clinical and diagnostic imaging are also discussed. PMID:25819467

  3. Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images.

    PubMed

    Goodsitt, Mitchell M; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C; Carson, Paul L

    2014-10-01

    The effect of acquisition geometry in digital breast tomosynthesis was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R = 0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R = 0.83). PMID:25211509

  4. Increasing the darkfield contrast-to-noise ratio using a deconvolution-based information retrieval algorithm in X-ray grating-based phase-contrast imaging.

    PubMed

    Weber, Thomas; Pelzer, Georg; Bayer, Florian; Horn, Florian; Rieger, Jens; Ritter, André; Zang, Andrea; Durst, Jürgen; Anton, Gisela; Michel, Thilo

    2013-07-29

    A novel information retrieval algorithm for X-ray grating-based phase-contrast imaging based on the deconvolution of the object and the reference phase stepping curve (PSC) as proposed by Modregger et al. was investigated in this paper. We applied the method for the first time on data obtained with a polychromatic spectrum and compared the results to those, received by applying the commonly used method, based on a Fourier analysis. We confirmed the expectation, that both methods deliver the same results for the absorption and the differential phase image. For the darkfield image, a mean contrast-to-noise ratio (CNR) increase by a factor of 1.17 using the new method was found. Furthermore, the dose saving potential was estimated for the deconvolution method experimentally. It is found, that for the conventional method a dose which is higher by a factor of 1.66 is needed to obtain a similar CNR value compared to the novel method. A further analysis of the data revealed, that the improvement in CNR and dose efficiency is due to the superior background noise properties of the deconvolution method, but at the cost of comparability between measurements at different applied dose values, as the mean value becomes dependent on the photon statistics used. PMID:23938672

  5. Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images

    NASA Astrophysics Data System (ADS)

    Goodsitt, Mitchell M.; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A.; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C.; Carson, Paul L.

    2014-10-01

    The effect of acquisition geometry in digital breast tomosynthesis was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R = 0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R = 0.83).

  6. Digital breast tomosynthesis: Studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images

    PubMed Central

    Goodsitt, Mitchell M.; Chan, Heang-Ping; Schmitz, Andrea; Zelakiewicz, Scott; Telang, Santosh; Hadjiiski, Lubomir; Watcharotone, Kuanwong; Helvie, Mark A.; Paramagul, Chintana; Neal, Colleen; Christodoulou, Emmanuel; Larson, Sandra C.; Carson, Paul L.

    2014-01-01

    The effect of acquisition geometry in digital breast tomosynthesis (DBT) was evaluated with studies of contrast-to-noise ratios (CNRs) and observer preference. Contrast-detail (CD) test objects in 5 cm thick phantoms with breast-like backgrounds were imaged. Twelve different angular acquisitions (average glandular dose for each ~1.1 mGy) were performed ranging from narrow angle 16° with 17 projection views (16d17p) to wide angle 64d17p. Focal slices of SART-reconstructed images of the CD arrays were selected for CNR computations and the reader preference study. For the latter, pairs of images obtained with different acquisition geometries were randomized and scored by 7 trained readers. The total scores for all images and readings for each acquisition geometry were compared as were the CNRs. In general, readers preferred images acquired with wide angle as opposed to narrow angle geometries. The mean percent preferred was highly correlated with tomosynthesis angle (R=0.91). The highest scoring geometries were 60d21p (95%), 64d17p (80%), and 48d17p (72%); the lowest scoring were 16d17p (4%), 24d9p (17%) and 24d13p (33%). The measured CNRs for the various acquisitions showed much overlap but were overall highest for wide-angle acquisitions. Finally, the mean reader scores were well correlated with the mean CNRs (R=0.83). PMID:25211509

  7. Crimson Carrier, A Long-Acting Contrast Agent for In Vivo Near-Infrared Imaging of Injured and Diseased Muscle

    PubMed Central

    Prajapati, Suresh I.; Martinez, Carlo O.; Abraham, Jinu; McCleish, Amanda T.; Michalek, Joel E.; McManus, Linda M.; Rubin, Brian P.; Shireman, Paula K.; Keller, Charles

    2010-01-01

    Introduction The near-infrared wavelengths (700nm–900nm) are the most suitable optical window for light penetration and deep tissue imaging in small animals. Herein we report a near-infrared fluorescent contrast agent, crimson carrier, which acts as a blood pool contrast agent to detect and quantify injury and disease in live animals. Methods After determining the excitation-emission spectra and pharmacokinetics, crimson carrier was injected into myoinjured mice to monitor their recovery. Crimson carrier was also used to image transgenic mice with spontaneous tumors. Results Crimson carrier has maximal excitation and emission wavelengths of 745 nm and 820 nm, respectively. Elimination occurs predominantly via urinary excretion. Discussion We demonstrate the utility of this contrast agent for serial imaging of traumatized muscle as well as muscle tumors. The unique long-acting pharmacokinetics and urinary excretion route characteristics make crimson carrier a contrast agent of choice for the visualization of tumors and injured muscle or other tissues in live animal studies. PMID:20544935

  8. High ambient-contrast-ratio display using tandem reflective liquid crystal display and organic light-emitting device

    NASA Astrophysics Data System (ADS)

    Lee, Jiun-Haw; Zhu, Xinyu; Lin, Yi-Hsin; Kit Choi, Wing; Lin, Tien-Chun; Hsu, Sheng-Chih; Lin, Hoang-Yan; Wu, Shin-Tson

    2005-11-01

    A high ambient-contrast-ratio (A-CR) and large aperture-ratio display is conceptually demonstrated and experimentally validated by stacking a normally black reflective liquid crystal display (NB-RLCD) and an organic light-emitting device (OLED). Such a tandem device can be switched between the NB-RLCD mode and the OLED mode under bright and dark ambient light, respectively. The normally black characteristic of the RLCD also helps to boost the A-CR under OLED-mode operation. To obtain a better image quality in the RLCD mode, a bumpy and transmissive structure is used to eliminate the specular reflection and to increase the viewing angle performance that results in CR>2:1 over 55° viewing cone. Besides, such a structure can also increase the external quantum efficiency of the OLED by 49.4%. In our experiments, regardless of the ambient intensity the A-CR is kept higher than 100:1.

  9. [Comparison of Contrast to Noise Ratio and Signal Difference to Noise Ratio Based on QA and QC Guidelines in CR Mammography].

    PubMed

    Nagami, Akiko; Ishii, Mie; Ishii, Rie; Kodama, Sayaka; Sanada, Taizo; Yoshida, Akira

    2016-06-01

    The measurement methods of contrast to noise ratio (CNR) and signal difference to noise ratio (SDNR) in digital mammography are different among several quality assurance (QA) guidelines, that is, the type of pixel value (PV), phantom shape, location of aluminum plate, and the size of region of interest (ROI) principally differ in data acquisition. We compared CNR (SDNR) obtained from three QA guidelines. They are the European Reference Organisation for Quality Assured Breast Screening and Diagnostic Services (EUREF), the International Electrotechnical Commission (IEC), and the International Atomic Energy Agency (IAEA). In EUREF and IEC, CNR was calculated using linearized pixel value (LPV). In IAEA, because the type of pixel value to use in SDNR was not specified, SDNR was calculated using PV and LPV, and CNR was calculated using LPV. Target/filter combinations are molybdenum/molybdenum (Mo/Mo) and molybdenum/rhodium (Mo/Rh). Applied various tube voltages are 25, 30, and 35 kV, and various phantom thicknesses are 20, 45, and 70 mm of polymethyl methacrylate (PMMA). The PV-SDNR of IAEA showed the largest value among the three methods, following LPV-CNR of IEC, LPV-CNR of EUREF at 20 mm PMMA thickness. In IAEA, SDNR changed by the kind of pixel value (PV or LPV). When CNR is calculated, every researcher should describe the type of guidelines, the kind of pixel value, and formula for calculation. PMID:27320154

  10. Contrast reversal of the eyes impairs infants' face processing: a near-infrared spectroscopic study.

    PubMed

    Ichikawa, Hiroko; Otsuka, Yumiko; Kanazawa, So; Yamaguchi, Masami K; Kakigi, Ryusuke

    2013-11-01

    Human can easily detect other's eyes and gaze from early in life. Such sensitivity is supported by the contrast polarity of human eyes, which have a white sclera contrasting with the darker colored iris (Kobayashi & Kohshima, (1997). Nature, 387, 767-768; Kobayashi & Kohshima, (2001). Journal of Human Evolution, 40, 419-435). Recent studies suggest that the contrast polarity around the eyes plays an important role in infants' face processing. Newborns preferred upright face images to inverted ones in contrast-preserved faces, but not in contrast-reversed faces (Farroni et al., (2005). Proceedings of National Academy of Sciences of the United States of America, 102, p. 17245-17250). Seven- to 8-month-old infants failed to discriminate between faces when the contrast polarity of eyes was reversed (Otsuka et al., (2013). Journal of Experimental Child Psychology, 115, 598-606). Neuroimaging study with adults revealed that full-negative faces induced less activation in the right fusiform gyrus than either full-positive faces or negative faces with contrast-preserved eyes (Gilad et al., (2009). Proceedings of National Academy of Sciences of the United States of America, 106, p. 5353-5358). In the present study, we investigated whether contrast-reversed eyes diminish infants' brain activity related to face processing. We measured hemodynamic responses in the bilateral temporal area of 5- to 6-month-old infants. Their hemodynamic responses to faces with positive eyes and those with negative eyes were compared against the baseline activation during the presentation of object images. We found that the presentation of faces with positive eyes increased the concentration of oxy-Hb in the right temporal area and those of total-Hb in the bilateral temporal areas. No such change occurred for faces with negative eyes. Our results suggest the importance of contrast polarity of the eyes in the face-selective neural responses from early development. PMID:24012650

  11. Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit

    NASA Astrophysics Data System (ADS)

    Kishikawa, Hiroki; Makimoto, Yoshihiro; Inoshita, Kensuke; Igarashi, Sanae; Goto, Nobuo; Yanagiya, Shin-ichiro

    2016-05-01

    In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed waveguide-type optical circuits for recognition of optical labels encoded in quadriphase-shift-keying (QPSK) form. A basic device for the circuits consists of a 3-dB directional coupler, two Y-branches, and an asymmetric X-junction coupler. We employed a scheme of complete interference of optical waves between each coded pulse and a reference pulse in our previously reported paper. The contrast ratio of the output at the destination output port to the outputs at the other ports was reported to decrease to 1.6, 1.28, and 1.13 for two-, three-, and four-stage circuits for recognition of 16, 64, and 256 QPSK labels, respectively. We find optimum circuits with improved contrast ratio of 1.8, 1.6, and 1.47 for 16, 64, and 256 labels, respectively. The recognition operation with the improved circuits is numerically confirmed using the beam propagation method. Noise tolerance of the proposed circuits is also clarified by numerical simulation. The improved circuits are optimum from the viewpoint of efficient use of optical power and noise tolerance.

  12. HIGH-CONTRAST NEAR-INFRARED IMAGING POLARIMETRY OF THE PROTOPLANETARY DISK AROUND RY TAU

    SciTech Connect

    Takami, Michihiro; Karr, Jennifer L.; Kim, Hyosun; Chou, Mei-Yin; Hashimoto, Jun; Kandori, Ryo; Kusakabe, Nobuhiko; Kwon, Jungmi; Wisniewski, John; Henning, Thomas; Brandner, Wolfgang; Grady, Carol A.; Hodapp, Klaus W.; Kudo, Tomoyuki; Itoh, Yoichi; Momose, Munetake; Mayama, Satoshi; Currie, Thayne; Follette, Katherine B.; Abe, Lyu; and others

    2013-08-01

    We present near-infrared coronagraphic imaging polarimetry of RY Tau. The scattered light in the circumstellar environment was imaged at the H band at a high resolution ({approx}0.''05) for the first time, using Subaru/HiCIAO. The observed polarized intensity (PI) distribution shows a butterfly-like distribution of bright emission with an angular scale similar to the disk observed at millimeter wavelengths. This distribution is offset toward the blueshifted jet, indicating the presence of a geometrically thick disk or a remnant envelope, and therefore the earliest stage of the Class II evolutionary phase. We perform comparisons between the observed PI distribution and disk models with (1) full radiative transfer code, using the spectral energy distribution (SED) to constrain the disk parameters; and (2) monochromatic simulations of scattered light which explore a wide range of parameters space to constrain the disk and dust parameters. We show that these models cannot consistently explain the observed PI distribution, SED, and the viewing angle inferred by millimeter interferometry. We suggest that the scattered light in the near-infrared is associated with an optically thin and geometrically thick layer above the disk surface, with the surface responsible for the infrared SED. Half of the scattered light and thermal radiation in this layer illuminates the disk surface, and this process may significantly affect the thermal structure of the disk.

  13. High-Contrast Near-Infrared Imaging Polarimetry of the Protoplanetary Disk around RY Tau

    NASA Technical Reports Server (NTRS)

    Takami, Michihiro; Karr, Jennifer L.; Hashimoto, Jun; Kim, Hyosun; Wisenewski, John; Henning, Thomas; Grady, Carol; Kandori, Ryo; Hodapp, Klaus W.; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Chou, Mei-yin; Itoh, Yoichi; Momose, Mumetake; Mayama, Satoshi; Currie, Thayne; Follette, Katherine B.; Kwon, Jungmi; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph; Egner, Sebastian E.; McElwain, Michael W.; Serabyn, Eugene

    2013-01-01

    We present near-infrared coronagraphic imaging polarimetry of RY Tau. The scattered light in the circumstellar environment was imaged at H-band at a high resolution (approx. 0.05) for the first time, using Subaru-HiCIAO. The observed polarized intensity (PI) distribution shows a butterfly-like distribution of bright emission with an angular scale similar to the disk observed at millimeter wavelengths. This distribution is offset toward the blueshifted jet, indicating the presence of a geometrically thick disk or a remnant envelope, and therefore the earliest stage of the Class II evolutionary phase. We perform comparisons between the observed PI distribution and disk models with: (1) full radiative transfer code, using the spectral energy distribution (SED) to constrain the disk parameters; and (2) monochromatic simulations of scattered light which explore a wide range of parameters space to constrain the disk and dust parameters. We show that these models cannot consistently explain the observed PI distribution, SED, and the viewing angle inferred by millimeter interferometry. We suggest that the scattered light in the near-infrared is associated with an optically thin and geometrically thick layer above the disk surface, with the surface responsible for the infrared SED. Half of the scattered light and thermal radiation in this layer illuminates the disk surface, and this process may significantly affect the thermal structure of the disk.

  14. Reconstruction of cerebral hemodynamics with dynamic contrast-enhanced time-resolved near-infrared measurements before and during ischemia

    NASA Astrophysics Data System (ADS)

    Elliott, Jonathan T.; Diop, Mamadou; Morrison, Laura B.; Lee, Ting-Yim; St. Lawrence, Keith

    2013-03-01

    We present a dynamic contrast-enhanced near-infrared (DCE-NIR) technique that is capable of non-invasive quantification of cerebral hemodynamics in adults. The challenge of removing extracerebral contamination is overcome through the use of multi-distance time-resolved DCE-NIR combined with the kinetic deconvolution optical reconstruction (KDOR) analytical method. As proof-of-principle, cerebral blood flow, cerebral blood volume and mean transit time recovered with DCE-NIR are compared with CT perfusion values in an adult pig during normocapnia, hypocapnia, and ischemia. Measurements of blood flow acquired with DCE-NIR were compared against concomitant measurements using CT Perfusion.

  15. Solvothermally Synthesized Sb2Te3 Platelets Show Unexpected Optical Contrasts in Mid-Infrared Near-Field Scanning Microscopy.

    PubMed

    Hauer, Benedikt; Saltzmann, Tobias; Simon, Ulrich; Taubner, Thomas

    2015-05-13

    We report nanoscale-resolved optical investigations on the local material properties of Sb2Te3 hexagonal platelets grown by solvothermal synthesis. Using mid-infrared near-field microscopy, we find a highly symmetric pattern, which is correlated to a growth spiral and which extends over the entire platelet. As the origin of the optical contrast, we identify domains with different densities of charge carriers. On Sb2Te3 samples grown by other means, we did not find a comparable domain structure. PMID:25868047

  16. An Explanation for the Observed Spectral Contrast Reduction Between Field and Laboratory Infrared Measurements of Soils

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Lucey, P. G.; Horton, K. A.; Williams, T.; Winter, E. M.; Stocker, A. D.

    1996-03-01

    Comparison of emission spectra (7-14 m) of pristine soils in the field with bidirectional reflectance spectra of soils obtained in the laboratory shows that laboratory spectra tend to have less contrast than field spectra. We investigated this phenomenon by measuring emission spectra of both pristine (in situ) and sampled soils (prepared as if for transport to the laboratory). The sampled soils had much less spectral contrast than the pristine soils in the reststrahlen region near 9 m. We hypothesize that this effect is due to a difference in grainsize distribution of the optically active layer (i.e., fine particle coatings). This concept was proposed by Salisbury et al. to explain their observations that soils washed free of small particles adhering to larger grains exhibited greater spectral contrast than unwashed soils. Unrecognized, this phenomenon could influence interpretations of remote sensing data since it is a common practice to use spectra of materials obtained in the laboratory to interpret spectra obtained remotely.

  17. Infrared measurements of pristine and disturbed soils 1. Spectral contrast differences between field and laboratory data

    USGS Publications Warehouse

    Johnson, J. R.; Lucey, P.G.; Horton, K.A.; Winter, E.M.

    1998-01-01

    Comparison of emissivity spectra (8-13 ??m) of pristine soils in the field with laboratory reflectance spectra of the same soils showed that laboratory spectra tend to have less spectral contrast than field spectra (see following article). We investigated this the phenomenon by measuring emission spectra of both undisturbed (in situ) and disturbed soils (prepared as if for transport to the laboratory). The disturbed soils had much less spectral contrast than the undisturbed soils in the reststrahlen region near 9 ??m. While the increased porosity of a disturbed soil can decrease spectral contrast due to multiple scattering, we hypothesize that the effect is dominantly the result of a difference in grain-size distribution of the optically active layer (i.e., fine particle coatings). This concept was proposed by Salisbury et al. (1994) to explain their observations that soils washed free of small particles adhering the larger grains exhibited greater spectral contrast than unwashed soils. Our laboratory reflectance spectra of wet- and dry-sieved soils returned from field sites also show greater spectral contrast for wet-sieved (washed) soils. We therefore propose that undisturbed soils in the field can be characterized as 'clean' soils (washed free of fine particles at the surface due to rain and wind action) and that disturbed soils represent 'dirty' soils (contaminated with fine particle coatings). The effect of packing soils in the field and laboratory also increases spectral contrast but not to the magnitude of that observed for undisturbed and wet-sieved soils. Since it is a common practice to use laboratory spectra of field samples to interpret spectra obtained remotely, we suggest that the influence of fine particle coatings on disturbed soils, if unrecognized, could influence interpretations of remote sensing data.Comparison of emissivity spectra (8-13 ??m) of pristine soils in the field with laboratory reflectance spectra of the same soils showed that

  18. The local stellar luminosity function and mass-to-light ratio in the near-infrared

    NASA Astrophysics Data System (ADS)

    Just, A.; Fuchs, B.; Jahreiß, H.; Flynn, C.; Dettbarn, C.; Rybizki, J.

    2015-07-01

    A new sample of stars, representative of the solar neighbourhood luminosity function (LF), is constructed from the Hipparcos catalogue and the Fifth Catalogue of Nearby Stars. We have cross-matched to sources in the Two Micron All Sky Survey catalogue so that for all stars individually determined near-infrared (NIR) photometry is available on a homogeneous system (typically Ks). The spatial completeness of the sample has been carefully determined by statistical methods, and the NIR LF of the stars has been derived by direct star counts. We find a local volume luminosity of 0.121 ± 0.004 LK⊙ pc-3, corresponding to a volumetric mass-to-light ratio (M/L) of M/L_K = 0.31 ± 0.02 {M}_{⊙}/L_{K⊙}, where giants contribute 80 per cent to the light but less than 2 per cent to the stellar mass. We derive the surface brightness of the solar cylinder with the help of a vertical disc model. We find a surface brightness of 99 LK⊙ pc-2 with an uncertainty of approximately 10 per cent. This corresponds to an M/L for the solar cylinder of M/L_K = 0.34 {M}_{⊙}/L_{K⊙}. The M/L for the solar cylinder is only 10 per cent larger than the local value despite the fact that the local population has a much larger contribution of young stars. It turns out that the effective scaleheights of the lower main sequence carrying most of the mass is similar to that of the giants, which are dominating the NIR light. The corresponding colour for the solar cylinder is V - K = 2.89 mag compared to the local value of V - K = 2.46 mag. An extrapolation of the local surface brightness to the whole Milky Way yields a total luminosity of MK = -24.2 mag. The Milky Way falls in the range of K band Tully-Fisher relations from the literature.

  19. Developments Toward Diagnostic Breast Cancer Imaging Using Near-Infrared Optical Measurements and Fluorescent Contrast Agents1

    PubMed Central

    Hawrysz, Daniel J; Sevick-Muraca, Eva M

    2000-01-01

    Abstract The use of near-infrared (NIR) light to interrogate deep tissues has enormous potential for molecular-based imaging when coupled with NIR excitable dyes. More than a decade has now passed since the initial proposals for NIR optical tomography for breast cancer screening using time-dependent measurements of light propagation in the breast. Much accomplishment in the development of optical mammography has been demonstrated, most recently in the application of time-domain, frequency-domain, and continuous-wave measurements that depend on endogenous contrast owing to angiogenesis and increased hemoglobin absorbance for contrast. Although exciting and promising, the necessity of angiogenesis-mediated absorption contrast for diagnostic optical mammography minimizes the potential for using NIR techniques to assess sentinel lymph node staging, metastatic spread, and multifocality of breast disease, among other applications. In this review, we summarize the progress made in the development of optical mammography, and focus on the emerging work underway in the use of diagnostic contrast agents for the molecular-based, diagnostic imaging of breast. PMID:11191107

  20. Noninvasive photoacoustic angiography of animal brains in vivo with near-infrared light and an optical contrast agent

    NASA Astrophysics Data System (ADS)

    Wang, Xueding; Ku, Geng; Wegiel, Malgorzata A.; Bornhop, Darryl J.; Stoica, George; Wang, Lihong V.

    2004-04-01

    Optical contrast agents have been widely applied to enhance the sensitivity and specificity of optical imaging with near-infrared (NIR) light. However, because of the overwhelming scattering of light in biological tissues, the spatial resolution of traditional optical imaging degrades drastically as the imaging depth increases. Here, for the first time to our knowledge, we present noninvasive photoacoustic angiography of animal brains in vivo with NIR light and an optical contrast agent. When indocyanine green polyethylene glycol, a novel absorption dye with prolonged clearance, is injected into the circulatory system of a rat, it obviously enhances the absorption contrast between the blood vessels and the background tissues. Because NIR light can penetrate deep into the brain tissues through the skin and skull, we are able to successfully reconstruct the vascular distribution in the rat brain from the photoacoustic signals. On the basis of differential optical absorption with and without contrast enhancement, a photoacoustic angiograph of a rat brain is acquired that matches the anatomical photograph well and exhibits high spatial resolution and a much-reduced background. This new technology demonstrates the potential for dynamic and molecular biomedical imaging.

  1. Measurement of contrast of phantom and in vivo subsurface blood vessels using two near-infrared imaging systems

    NASA Astrophysics Data System (ADS)

    Hebden, Jeremy C.; Alkhaja, Aysha; Mahe, Laure; Powell, S.; Everdell, N. L.

    2015-03-01

    A quantitative comparison has been performed between two commercial near-infrared (NIR) vein-viewing systems which are designed to supplement the clinician's traditional skills in locating veins by means of visualization and palpation. The AccuVein AV300 and Novarix IV-eye real-time imaging systems employ very different imaging geometries; the former generates an image from reflected NIR light produced by a beam scanned across the surface, while the latter illuminates the viewed region at four points on the periphery and records the resulting distribution of diffusely transmitted light. The comparison involved measuring the contrast produced by absorbing rods (simulated blood vessels) in a cylindrical phantom with tissue-like optical properties, and the contrast of superficial blood vessels in the arms of healthy volunteers. The locations and sizes of the blood vessels were independently verified using a clinical ultrasound imaging system. The phantom measurements suggested that the AV300 displays the most superficial vessels with greater contrast, but the IV-eye is able to detect vessels when they are at a depth up to 2 mm greater than the limit observed for the AV300. The results for thirty healthy volunteers also indicated that the AV300 typically displays vessels with higher overall contrast, but the effectiveness of the IV-eye at visualizing deeper vessels was even more pronounced, with a maximum depth several millimeters greater than that achieved by the AV300, and more than ten times as many vessels observed at depths below 4 mm.

  2. The effect of particle size and porosity on spectral contrast in the mid-infrared

    USGS Publications Warehouse

    Salisbury, J.W.; Eastes, J.W.

    1985-01-01

    Contrary to previous work, we find that the decreasing intensity of fundamental molecular vibration bands with decreasing particle size is due primarily to increasing porosity of the finer particle size ranges, rather than to particle size per se. This implies that laser reflectance measurements from orbiting spacecraft should avoid loss of spectral contrast for fine particulate surfaces, because such measurements near zero phase angle will benefit from the opposition effect. ?? 1985.

  3. Ratio

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

    2014-12-01

    Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

  4. High ambient-contrast-ratio display using tandem reflective liquid crystal display and organic light-emitting device.

    PubMed

    Lee, Jiun-Haw; Zhu, Xinyu; Lin, Yi-Hsin; Choi, Wing; Lin, Tien-Chun; Hsu, Sheng-Chih; Lin, Hoang-Yan; Wu, Shin-Tson

    2005-11-14

    A high ambient-contrast-ratio (A-CR) and large aperture-ratio display is conceptually demonstrated and experimentally validated by stacking a normally black reflective liquid crystal display (NB-RLCD) and an organic light-emitting device (OLED). Such a tandem device can be switched between the NB-RLCD mode and the OLED mode under bright and dark ambient light, respectively. The normally black characteristic of the RLCD also helps to boost the A-CR under OLED-mode operation. To obtain a better image quality in the RLCD mode, a bumpy and transmissive structure is used to eliminate the specular reflection and to increase the viewing angle performance that results in CR>2:1 over 55 degrees viewing cone. Besides, such a structure can also increase the external quantum efficiency of the OLED by 49.4%. In our experiments, regardless of the ambient intensity the A-CR is kept higher than 100:1. PMID:19503145

  5. Mid-infrared High-contrast Imaging of HD 114174 B: An Apparent Age Discrepancy in a "Sirius-like" Binary System

    NASA Astrophysics Data System (ADS)

    Matthews, Christopher T.; Crepp, Justin R.; Skemer, Andrew; Hinz, Philip M.; Gianninas, Alexandros; Kilic, Mukremin; Skrutskie, Michael; Bailey, Vanessa P.; Defrere, Denis; Leisenring, Jarron; Esposito, Simone; Puglisi, Alfio

    2014-03-01

    We present new observations of the faint "Sirius-like" companion discovered to orbit HD 114174. Previous attempts to image HD 114174 B at mid-infrared wavelengths using NIRC2 at Keck have resulted in a non-detection. Our new L'-band observations taken with the Large Binocular Telescope and L/M-band InfraRed Camera recover the companion (ΔL = 10.15 ± 0.15 mag, ρ = 0.''675 ± 0.''016) with a high signal-to-noise ratio (10σ). This measurement represents the deepest L' high-contrast imaging detection at subarcsecond separations to date, including extrasolar planets. We confirm that HD 114174 B has near-infrared colors consistent with the interpretation of a cool white dwarf (WD; J - L' = 0.76 ± 0.19 mag, K - L' = 0.64 ± 0.20). New model fits to the object's spectral energy distribution indicate a temperature T eff = 4260 ± 360 K, surface gravity log g = 7.94 ± 0.03, a cooling age tc ≈ 7.8 Gyr, and mass M = 0.54 ± 0.01 M ⊙. We find that the cooling ages given by theoretical atmospheric models do not agree with the age of HD 114174 A derived from both isochronological and gyrochronological analyses. We speculate on possible scenarios to explain the apparent age discrepancy between the primary and secondary. HD 114174 B is a nearby benchmark WD that will ultimately enable a dynamical mass estimate through continued Doppler and astrometric monitoring. Efforts to characterize its physical properties in detail will test theoretical atmospheric models and improve our understanding of WD evolution, cooling, and progenitor masses.

  6. MID-INFRARED HIGH-CONTRAST IMAGING OF HD 114174 B: AN APPARENT AGE DISCREPANCY IN A ''SIRIUS-LIKE'' BINARY SYSTEM

    SciTech Connect

    Matthews, Christopher T.; Crepp, Justin R.; Skemer, Andrew; Hinz, Philip M.; Bailey, Vanessa P.; Defrere, Denis; Leisenring, Jarron; Gianninas, Alexandros; Kilic, Mukremin; Skrutskie, Michael; Esposito, Simone; Puglisi, Alfio

    2014-03-10

    We present new observations of the faint ''Sirius-like'' companion discovered to orbit HD 114174. Previous attempts to image HD 114174 B at mid-infrared wavelengths using NIRC2 at Keck have resulted in a non-detection. Our new L'-band observations taken with the Large Binocular Telescope and L/M-band InfraRed Camera recover the companion (ΔL = 10.15 ± 0.15 mag, ρ = 0.''675 ± 0.''016) with a high signal-to-noise ratio (10σ). This measurement represents the deepest L' high-contrast imaging detection at subarcsecond separations to date, including extrasolar planets. We confirm that HD 114174 B has near-infrared colors consistent with the interpretation of a cool white dwarf (WD; J – L' = 0.76 ± 0.19 mag, K – L' = 0.64 ± 0.20). New model fits to the object's spectral energy distribution indicate a temperature T {sub eff} = 4260 ± 360 K, surface gravity log g = 7.94 ± 0.03, a cooling age t{sub c} ≈ 7.8 Gyr, and mass M = 0.54 ± 0.01 M {sub ☉}. We find that the cooling ages given by theoretical atmospheric models do not agree with the age of HD 114174 A derived from both isochronological and gyrochronological analyses. We speculate on possible scenarios to explain the apparent age discrepancy between the primary and secondary. HD 114174 B is a nearby benchmark WD that will ultimately enable a dynamical mass estimate through continued Doppler and astrometric monitoring. Efforts to characterize its physical properties in detail will test theoretical atmospheric models and improve our understanding of WD evolution, cooling, and progenitor masses.

  7. Quantitative analysis of melamine in milk powders using near-infrared hyperspectral imaging and band ratio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since 2008, the detection of the adulterant melamine (2,4,6-triamino-1,3,5-triazine) in food products has become the subject of research due to several food safety scares. Near-infrared (NIR) hyperspectral imaging offers great potential for food safety and quality research because it combines the fe...

  8. Near-infrared absorbing polymer nano-particle as a sensitive contrast agent for photo-acoustic imaging.

    PubMed

    Aoki, Hiroyuki; Nojiri, Mayumi; Mukai, Rieko; Ito, Shinzaburo

    2015-01-01

    Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 10(10) M(-1) cm(-1). This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grüneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10(-13) M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging. PMID:25407911

  9. Nitrogen Isotopic Ratio in Jupiter's Atmosphere from Observations by Composite Infrared Spectrometer (CIRS) on the Cassini Spacecraft

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; LeClair, A.; Owen, T.; Conrath, B. J.; Flasar, F. M.; Kunde, V. G.; Nixon, C. A..; Achterberg, R. K.; Bjoraker, G.; Jennings, D. J.

    2003-01-01

    The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft made infrared observations of Jupiter's atmosphere during the flyby in December 2000 to January 2001. The unique database in the 600-1400/cm region with 0.53 and 2.8/cm spectral resolutions obtained from the observations permits retrieval of global maps of the thermal structure and composition of Jupiter's atmosphere including the distributions of (14)NH3 and (15)NH3. Analysis of Jupiter's ammonia distributions from three isolated (15)NH3 spectral lines in eight latitudes is presented for evaluation of the nitrogen isotopic ratio. The nitrogen isotopic ratio (14)N/(15)N (or (15)N/(14)N) in Jupiter's atmosphere in this analysis is calculated to be: 448 +/- 62 ((2.23 +/- 0.31) x 10(exp -3)). This value of the ratio determined from CIRS data is found to be in very close agreement with the value previously obtained from the measurements by the Galileo Probe Mass Spectrometer. Some possible mechanisms to account for the variation of Jupiter's observed isotopic ratio relative to various astrophysical environments are discussed.

  10. Contrast, size, and orientation-invariant target detection in infrared imagery

    NASA Astrophysics Data System (ADS)

    Zhou, Yi-Tong; Crawshaw, Richard D.

    1991-08-01

    Automatic target detection in IR imagery is a very difficult task due to variations in target brightness, shape, size, and orientation. In this paper, the authors present a contrast, size, and orientation invariant algorithm based on Gabor functions for detecting targets from a single IR image frame. The algorithms consists of three steps. First, it locates potential targets by using low-resolution Gabor functions which resist noise and background clutter effects, then, it removes false targets and eliminates redundant target points based on a similarity measure. These two steps mimic human vision processing but are different from Zeevi's Foveating Vision System. Finally, it uses both low- and high-resolution Gabor functions to verify target existence. This algorithm has been successfully tested on several IR images that contain multiple examples of military vehicles with different size and brightness in various background scenes and orientations.

  11. A fusion method for visible and infrared images based on contrast pyramid with teaching learning based optimization

    NASA Astrophysics Data System (ADS)

    Jin, Haiyan; Wang, Yanyan

    2014-05-01

    This paper proposes a novel image fusion scheme based on contrast pyramid (CP) with teaching learning based optimization (TLBO) for visible and infrared images under different spectrum of complicated scene. Firstly, CP decomposition is employed into every level of each original image. Then, we introduce TLBO to optimizing fusion coefficients, which will be changed under teaching phase and learner phase of TLBO, so that the weighted coefficients can be automatically adjusted according to fitness function, namely the evaluation standards of image quality. At last, obtain fusion results by the inverse transformation of CP. Compared with existing methods, experimental results show that our method is effective and the fused images are more suitable for further human visual or machine perception.

  12. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope

    NASA Astrophysics Data System (ADS)

    Pandya, Shwetang N.; Peterson, Byron J.; Mukai, Kiyofumi; Sano, Ryuichi; Enokuchi, Akito; Takeyama, Norihide

    2014-07-01

    An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the square root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ0 = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details.

  13. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope.

    PubMed

    Pandya, Shwetang N; Peterson, Byron J; Mukai, Kiyofumi; Sano, Ryuichi; Enokuchi, Akito; Takeyama, Norihide

    2014-07-01

    An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the square root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ0 = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details. PMID:25085127

  14. Improved signal to noise ratio and sensitivity of an infrared imaging video bolometer on large helical device by using an infrared periscope

    SciTech Connect

    Pandya, Shwetang N. Sano, Ryuichi; Peterson, Byron J.; Mukai, Kiyofumi; Enokuchi, Akito; Takeyama, Norihide

    2014-07-15

    An Infrared imaging Video Bolometer (IRVB) diagnostic is currently being used in the Large Helical Device (LHD) for studying the localization of radiation structures near the magnetic island and helical divertor X-points during plasma detachment and for 3D tomography. This research demands high signal to noise ratio (SNR) and sensitivity to improve the temporal resolution for studying the evolution of radiation structures during plasma detachment and a wide IRVB field of view (FoV) for tomography. Introduction of an infrared periscope allows achievement of a higher SNR and higher sensitivity, which in turn, permits a twofold improvement in the temporal resolution of the diagnostic. Higher SNR along with wide FoV is achieved simultaneously by reducing the separation of the IRVB detector (metal foil) from the bolometer's aperture and the LHD plasma. Altering the distances to meet the aforesaid requirements results in an increased separation between the foil and the IR camera. This leads to a degradation of the diagnostic performance in terms of its sensitivity by 1.5-fold. Using an infrared periscope to image the IRVB foil results in a 7.5-fold increase in the number of IR camera pixels imaging the foil. This improves the IRVB sensitivity which depends on the square root of the number of IR camera pixels being averaged per bolometer channel. Despite the slower f-number (f/# = 1.35) and reduced transmission (τ{sub 0} = 89%, due to an increased number of lens elements) for the periscope, the diagnostic with an infrared periscope operational on LHD has improved in terms of sensitivity and SNR by a factor of 1.4 and 4.5, respectively, as compared to the original diagnostic without a periscope (i.e., IRVB foil being directly imaged by the IR camera through conventional optics). The bolometer's field of view has also increased by two times. The paper discusses these improvements in apt details.

  15. Facile and high spatial resolution ratio-metric luminescence thermal mapping in microfluidics by near infrared excited upconversion nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Cao, Wenbin; Li, Shunbo; Wen, Weijia

    2016-02-01

    A local area temperature monitor is important for precise control of chemical and biological processes in microfluidics. In this work, we developed a facile method to realize micron spatial resolution of temperature mapping in a microfluidic channel quickly and cost effectively. Based on the temperature dependent fluorescence emission of NaYF4:Yb3+, Er3+ upconversion nanoparticles (UCNPs) under near-infrared irradiation, ratio-metric imaging of UCNPs doped polydimethylsiloxane can map detailed temperature distribution in the channel. Unlike some reported strategies that utilize temperature sensitive organic dye (such as Rhodamine) to achieve thermal sensing, our method is highly chemically inert and physically stable without any performance degradation in long term operation. Moreover, this method can be easily scaled up or down, since the spatial and temperature resolution is determined by an optical imaging system. Our method supplied a simple and efficient solution for temperature mapping on a heterogeneous surface where usage of an infrared thermal camera was limited.

  16. The C-12/C-13 ratio in Jupiter from the Voyager infrared investigation

    NASA Technical Reports Server (NTRS)

    Courtin, R.; Gautier, D.; Marten, A.; Kunde, V.

    1983-01-01

    An analysis of the v(4) band of CH4 in the spectra recorded by the Voyager 1 IRIS experiment has yielded a C-12/C-13 ratio in Jupiter that is 160 plus 40 or minus 55, or 1.8 plus 0.4 or minus 0.6 times the terrestrial value. It is noted that while no plausible theory predicts such a difference between the C-12/C-13 ratio values of Jupiter and the inner solar system, values of this ratio in the solar neighborhood 4.5 million years ago, inferred from recent interstellar medium measurements, are compatible with the present determination in Jupiter. The Jovian, rather than the terrestrial value, would then be representative of the carbon isotope ratio in the primitive solar nebula.

  17. Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Seong, Myeongsu; Phillips, Zephaniah; Mai, Phuong Minh; Yeo, Chaebeom; Song, Cheol; Lee, Kijoon; Kim, Jae Gwan

    2016-02-01

    A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements. In order to validate the system, a flow phantom test and an arm occlusion protocol for arterial and venous occlusion were performed. Shorter exposure times (<1 ms) show a higher drop (between 50% and 66%) and recovery of 1/KS2 values after occlusion (approximately 150%), but longer exposure time (3 ms) shows more consistent hemodynamic changes. For four subjects, the 1/KS2 values dropped to an average of 82.1±4.0% during the occlusion period and the average recovery of 1/KS2 values after occlusion was 109.1±0.8%. There was also an approximately equivalent amplitude change in oxyhemoglobin (OHb) and deoxyhemoglobin (RHb) during arterial occlusion (max RHb=0.0085±0.0024 mM/DPF, min OHb=-0.0057±0.0044 mM/DPF). The sensitivity of the system makes it a suitable modality to observe qualitative hemodynamic trends during induced physiological changes.

  18. High-contrast near-infrared studies of planetary systems and their circumstellar environments

    NASA Astrophysics Data System (ADS)

    Rodigas, Timothy John

    Planets are thought to form in circumstellar disks, leaving behind planetesimals that collide to produce dusty debris disks. Characterizing the architectures of planetary systems, along with the structures and compositions of debris disks, can therefore help answer questions about how planets form. In this thesis, I present the results of five papers (three published, two in preparation) concerning the properties of extrasolar planetary systems and their circumstellar environments. Chapters 2 and 3 are studies of radial velocity (RV) exoplanetary systems. For years astronomers have been puzzled about the large number of RV-detected planets that have eccentric orbits (e > 0.1). In Chapter 2 I show that this problem can partially be explained by showing that two circular-orbit planets can masquerade as a single planet on an eccentric orbit. I use this finding to predict that planets with mildly eccentric orbits are the most likely to have massive companions on wide orbits, potentially detectable by future direct imaging observations. Chapter 3 presents such a direct imaging study of the 14 Her planetary system. I significantly constrain the phase space of the putative candidate 14 Her c and demonstrate the power of direct imaging/RV overlap. Chapters 4 and 5 are high-contrast 2-4 micron imaging studies of the edge-on debris disks around HD 15115 and HD 32297. HD 15115's color is found to be gray, implying large grains 1-10 microns in size reside in stable orbits in the disk. HD 32297's disk color is red from 1-4 microns. Cometary material (carbon, silicates, and porous water ice) are a good match at 1-2 microns but not at L'. Tholins, organic material that is found in outer solar system bodies, or small silicates can explain the disk's red color but not the short wavelength data. Chapter 6 presents a dynamical study of dust grains in the presence of massive planets. I show that the width of a debris disk increases proportionally with the mass of its shepherding

  19. Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction using isotope ratio infrared spectroscopy.

    PubMed

    Chesson, Lesley A; Bowen, Gabriel J; Ehleringer, James R

    2010-11-15

    Hydrogen (δ(2)H) and oxygen (δ(18)O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy (IRIS; specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk 'as is' using IRIS. For IRIS analysis, four sequential injections of each sample were measured and data were corrected for sample-to-sample memory using injections (a) 1-4, (b) 2-4, and (c) 3-4. The variation between δ(2)H and δ(18)O values calculated using the three correction methods was larger for unextracted (i.e., complex) beverages than for waters. The memory correction was smallest when using injections 3-4. Beverage water δ(2)H and δ(18)O values generally fit the Global Meteoric Water Line, with the exception of water from fruit juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data and fit 1:1 lines, with the exception of sodas and juices (δ(2)H values) and beers (δ(18)O values). The δ(2)H and δ(18)O values of waters extracted from beer, soda, juice, and milk were correlated with complex beverage δ(2)H and δ(18)O values (r = 0.998 and 0.997, respectively) and generally fit 1:1 lines. We conclude that it is possible to analyze complex beverages, without water extraction, using IRIS although caution is needed when analyzing beverages containing sugars, which can clog the syringe and increase memory, or alcohol, a known spectral interference. PMID:20941769

  20. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.

    PubMed

    Keenan, F P; Aller, L H; Ryans, R S; Hyung, S

    2001-08-14

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676

  1. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae

    PubMed Central

    Keenan, Francis P.; Aller, Lawrence H.; Ryans, Robert S. I.; Hyung, Siek

    2001-01-01

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d6 levels of Fe III and among the 3d2 levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures Te = 7,000–20,000 K and densities Ne = 102-108 cm−3, whereas those for [Fe VII] are provided for Te = 10,000–30,000 K and Ne = 102-108 cm−3. The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027. PMID:11493676

  2. Quality assurance in MRI breast screening: comparing signal-to-noise ratio in dynamic contrast-enhanced imaging protocols.

    PubMed

    Kousi, Evanthia; Borri, Marco; Dean, Jamie; Panek, Rafal; Scurr, Erica; Leach, Martin O; Schmidt, Maria A

    2016-01-01

    MRI has been extensively used in breast cancer staging, management and high risk screening. Detection sensitivity is paramount in breast screening, but variations of signal-to-noise ratio (SNR) as a function of position are often overlooked. We propose and demonstrate practical methods to assess spatial SNR variations in dynamic contrast-enhanced (DCE) breast examinations and apply those methods to different protocols and systems. Four different protocols in three different MRI systems (1.5 and 3.0 T) with receiver coils of different design were employed on oil-filled test objects with and without uniformity filters. Twenty 3D datasets were acquired with each protocol; each dataset was acquired in under 60 s, thus complying with current breast DCE guidelines. In addition to the standard SNR calculated on a pixel-by-pixel basis, we propose other regional indices considering the mean and standard deviation of the signal over a small sub-region centred on each pixel. These regional indices include effects of the spatial variation of coil sensitivity and other structured artefacts. The proposed regional SNR indices demonstrate spatial variations in SNR as well as the presence of artefacts and sensitivity variations, which are otherwise difficult to quantify and might be overlooked in a clinical setting. Spatial variations in SNR depend on protocol choice and hardware characteristics. The use of uniformity filters was shown to lead to a rise of SNR values, altering the noise distribution. Correlation between noise in adjacent pixels was associated with data truncation along the phase encoding direction. Methods to characterise spatial SNR variations using regional information were demonstrated, with implications for quality assurance in breast screening and multi-centre trials. PMID:26605957

  3. Quality assurance in MRI breast screening: comparing signal-to-noise ratio in dynamic contrast-enhanced imaging protocols

    NASA Astrophysics Data System (ADS)

    Kousi, Evanthia; Borri, Marco; Dean, Jamie; Panek, Rafal; Scurr, Erica; Leach, Martin O.; Schmidt, Maria A.

    2016-01-01

    MRI has been extensively used in breast cancer staging, management and high risk screening. Detection sensitivity is paramount in breast screening, but variations of signal-to-noise ratio (SNR) as a function of position are often overlooked. We propose and demonstrate practical methods to assess spatial SNR variations in dynamic contrast-enhanced (DCE) breast examinations and apply those methods to different protocols and systems. Four different protocols in three different MRI systems (1.5 and 3.0 T) with receiver coils of different design were employed on oil-filled test objects with and without uniformity filters. Twenty 3D datasets were acquired with each protocol; each dataset was acquired in under 60 s, thus complying with current breast DCE guidelines. In addition to the standard SNR calculated on a pixel-by-pixel basis, we propose other regional indices considering the mean and standard deviation of the signal over a small sub-region centred on each pixel. These regional indices include effects of the spatial variation of coil sensitivity and other structured artefacts. The proposed regional SNR indices demonstrate spatial variations in SNR as well as the presence of artefacts and sensitivity variations, which are otherwise difficult to quantify and might be overlooked in a clinical setting. Spatial variations in SNR depend on protocol choice and hardware characteristics. The use of uniformity filters was shown to lead to a rise of SNR values, altering the noise distribution. Correlation between noise in adjacent pixels was associated with data truncation along the phase encoding direction. Methods to characterise spatial SNR variations using regional information were demonstrated, with implications for quality assurance in breast screening and multi-centre trials.

  4. Detailed assessment of isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters.

    PubMed

    Zhao, Liangju; Xiao, Honglang; Zhou, Jian; Wang, Lixin; Cheng, Guodong; Zhou, Maoxian; Yin, Li; McCabe, Matthew F

    2011-10-30

    As an alternative to isotope ratio mass spectrometry (IRMS), the isotope ratio infrared spectroscopy (IRIS) approach has the advantage of low cost, continuous measurement and the capacity for field-based application for the analysis of the stable isotopes of water. Recent studies have indicated that there are potential issues of organic contamination of the spectral signal in the IRIS method, resulting in incorrect results for leaf samples. To gain a more thorough understanding of the effects of sample type (e.g., leaf, root, stem and soil), sample species, sampling time and climatic condition (dry vs. wet) on water isotope estimates using IRIS, we collected soil samples and plant components from a number of major species at a fine temporal resolution (every 2 h for 24-48 h) across three locations with different climatic conditions in the Heihe River Basin, China. The hydrogen and oxygen isotopic compositions of the extracted water from these samples were measured using both an IRMS and an IRIS instrument. The results show that the mean discrepancies between the IRMS and IRIS approaches for δ(18) O and δD, respectively, were: -5.6‰ and -75.7‰ for leaf water; -4.0‰ and -23.3‰ for stem water; -3.4‰ and -28.2‰ for root water; -0.5‰ and -6.7‰ for xylem water; -0.06‰ and -0.3‰ for xylem flow; and -0.1‰ and 0.3‰ for soil water. The order of the discrepancy was: leaf > stem ≈ root > xylem > xylem flow ≈ soil. In general, species of the same functional types (e.g., woody vs. herbaceous) within similar habitats showed similar deviations. For different functional types, the differences were large. Sampling at nighttime did not remove the observed deviations. PMID:21953962

  5. Discrepancies between isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters.

    PubMed

    West, Adam G; Goldsmith, Gregory R; Brooks, Paul D; Dawson, Todd E

    2010-07-30

    The use of isotope ratio infrared spectroscopy (IRIS) for the stable hydrogen and oxygen isotope analysis of water is increasing. While IRIS has many advantages over traditional isotope ratio mass spectrometry (IRMS), it may also be prone to errors that do not impact upon IRMS analyses. Of particular concern is the potential for contaminants in the water sample to interfere with the spectroscopy, thus leading to erroneous stable isotope data. Water extracted from plant and soil samples may often contain organic contaminants. The extent to which contaminants may interfere with IRIS and thus impact upon data quality is presently unknown. We tested the performance of IRIS relative to IRMS for water extracted from 11 plant species and one organic soil horizon. IRIS deviated considerably from IRMS for over half of the samples tested, with deviations as large as 46 per thousand (delta(2)H) and 15.4 per thousand (delta(18)O) being measured. This effect was reduced somewhat by using activated charcoal to remove organics from the water; however, deviations as large as 35 per thousand (delta(2)H) and 11.8 per thousand (delta(18)O) were still measured for these cleaned samples. Interestingly, the use of activated charcoal to clean water samples had less effect than previously thought for IRMS analyses. Our data show that extreme caution is required when using IRIS to analyse water samples that may contain organic contaminants. We suggest that the development of new cleaning techniques for removing organic contaminants together with instrument-based software to flag potentially problematic samples are necessary to ensure accurate plant and soil water analyses using IRIS. PMID:20552579

  6. Detailed assessment of isotope ratio infrared spectroscopy and isotope ratio mass spectrometry for the stable isotope analysis of plant and soil waters

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Xiao, H.; Zhou, J.; Wang, L.; Cheng, G.; Zhou, M.; Yin, L.; McCabe, M. F.

    2011-12-01

    As an alternative to isotope ratio mass spectrometry (IRMS) the isotope ratio infrared spectroscopy (IRIS) approach has the advantage of low cost, continuous measurement and capacity for field based application for the analysis of stable water isotopes. Recent studies have indicated that there are potential issues of organic contamination of the spectral signal in the IRIS method, resulting in errant readings for leaf samples. To gain a more thorough understanding of the effects of sample type (e.g., leaf, root, stem and soil), sample species, sampling time and climatic condition (dry vs. wet) on water isotope estimates using IRIS, we collected soil samples and plant components from a number of major species at a fine temporal resolution (every two hours for 24-48 hours) across three locations with different climatic conditions in the Heihe River Basin, China. The hydrogen and oxygen isotopic composition of the extracted water from these samples was measured using both an IRMS and IRIS instrument. Results show that the mean discrepancy between the IRMS and IRIS approach, for δ18O and δD respectively, was: -5.6% and -75.7% for leaf water; -4.0% and -23.3% for stem water; -3.4% and -28.2% for root water; -6.7% and -0.5% for xylem water; -0.06% and -0.3% for xylem flow; and -0.1% and 0.3% for soil water. The order of the discrepancy followed: leaf > stem ≈ root > xylem > xylem flow ≈ soil. In general, species of the same functional types (e.g., woody vs. herbaceous) within similar habitats showed similar deviations. For different functional types, the differences were large. Sampling during the nighttime did not remove the observed deviations.

  7. The C/H ratio in Jupiter from the Voyager infrared investigation

    NASA Technical Reports Server (NTRS)

    Gautier, D.; Bezard, B.; Marten, A.; Baluteau, J. P.; Scott, N.; Chedin, A.; Kunde, K.; Hanel, R.

    1982-01-01

    From a selection Voyager IRIS spectra corresponding to cloud-free areas of Jupiter, the CH4/H2 volume ratio in the atmosphere of this planet has been determined to be equal to 0.00195 + or - 0.00022, which corresponds to 2.07 + or - 0.24 times the solar value of Lambert (C/H = 0.00047). The estimate of errors includes both instrument noise and systematic uncertainties. Implications of this result for the formation and evolution of Jupiter are discussed.

  8. C/H ratio in Jupiter from the Voyager infrared investigation

    SciTech Connect

    Gautier, D.; Bezard, B.; Marten, A.; Baluteau, J.P.; Scott, N.; Chedin, A.; Kunde, V.; Hanel, R.

    1982-06-15

    From a selection of Voyager IRIS spectra corresponding to cloud-free areas of Jupiter, we have determined the CH/sub 4//H/sub 2/ volume ratio in the atmosphere of this planet as equal to (1.95 +- 0.22)10/sup -3/ which corresponds to 2.07 +- 0.24 times the solar value of Lambert (C/H = 4.7 x 10/sup -4/). Estimate of errors includes both instrument noise and systematic uncertainties. Implications of this result on the formation and evolution of Jupiter are discussed.

  9. Monte Carlo evaluation of the relationship between absorbed dose and contrast-to-noise ratio in coherent scatter breast CT

    NASA Astrophysics Data System (ADS)

    Ghammraoui, B.; Popescu, L. M.; Badal, A.

    2015-03-01

    The objective of this work was to evaluate the advantages and shortcomings associated with Coherent Scatter Computed Tomography (CSCT) systems for breast imaging and study possible alternative configurations. The relationship between dose in a breast phantom and a simple surrogate of image quality in pencil-beam and fan-beam CSCT geometries was evaluated via Monte Carlo simulation, and an improved pencil-beam setup was proposed for faster CSCT data acquisition. CSCT projection datasets of a simple breast phantom have been simulated using a new version of the MC-GPU code that includes an improved model of x-ray coherent scattering using experimentally measured molecular interference functions. The breast phantom was composed of an 8 cm diameter cylinder of 50/50 glandular/adipose material and nine rods with different diameters of cancerous, adipose and glandular tissues. The system performance has been assessed in terms of the contrast-to-noise ratio (CNR) in multiple regions of interest within the reconstructed images, for a range of exposure levels. The enhanced pencil-beam setup consisted of multiplexed pencil beams and specific post-processing of the projection data to calculate the scatter intensity coming from each beam separately. At reconstruction spatial resolution of 1×1×1 mm3 and from 1 to 10 mGy of received breast dose, fan-beam geometry showed higher statistical noise and lower CNR than pencil-beam geometry. Conventional CT acquisition had the highest CNR per dose. However, the CNR figure of merit did not combine yet all the information available at different scattering angles in the CSCT, which has potential for increased discrimination of materials with similar attenuation properties. Preliminary evaluation of the multiplexed pencil-beam geometry showed that the scattering profiles simulated with the new approach are similar to those of the single pencil-beam geometry. Conclusion: It has been shown that the GPU-accelerated MC-GPU code is a practical

  10. Enhancing the Efficiency and Contrast Ratio of White Organic Light-Emitting Diode Using Energy-Recyclable Photovoltaic Cells

    NASA Astrophysics Data System (ADS)

    Yokoyama, Meiso; Wu, Chung-Ming; Su, Shui-Hsiang

    2012-03-01

    We demonstrate that power recycling is feasible by using a semitransparent strip of Al electrode as an interconnecting layer to merge a white organic light-emitting device (WOLED) and an organic photovoltaic (OPV) cell. The device is called a photovoltaic organic light-emitting device (PVOLED). It has a glass/indium tin oxide (ITO)/copper phthalocyanine (CuPc)/4,4,4-tris(3-methyl-phenylphenylamino) triphenylamine (m-MTDATA):V2O5/2-N',N-bis(1-naphthyl)-N,N'-diphenyl-1'-biphenyl-4,4'-diamine (NPB)/4,4'-bis(carbazol-9-yl)biphenyl (CBP):bis[3,5-difluoro-2-(2-pyridyl) phenyl-(2-carboxypyridyl)] iridium(II) (FIrpic):4-(dicyanomethylene)-2-t-butyl-6 (1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB)/4,7-diphenyl-1,10-phenanthroline (BPhen)/LiF/Al/poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61 butyric acid methyl ester (PCBM)/V2O5/Al structure. A power recycling efficiency of 10.133% is achieved using the WOLED of the PVOLED operated at 9 V and a brightness of 2110 cd/m2 when the conversion efficiency of the OPV cell is 2.3%. We found that the power recycling efficiency decreases at a high brightness and a high applied voltage owing to an increase in the input power of the WOLED. A high efficiency (18.3 cd/A) and a high contrast ratio (9.3) are obtained in the device operated at 2500 cd/m2 under an ambient illumination of 24000 lx. Reasonable white light emission with Commission Internationale De L'Eclairage (CIE) color coordinates of (0.32, 0.44) at 20 mA/cm2 and a slight color shift occur in spite of the high current density of 50 mA/cm2.

  11. Evaluating calibration strategies for isotope ratio infrared spectroscopy for atmospheric 13CO2/12CO2 measurement

    NASA Astrophysics Data System (ADS)

    Wen, X.-F.; Meng, Y.; Zhang, X.-Y.; Sun, X.-M.; Lee, X.

    2013-01-01

    Isotope ratio infrared spectroscopy (IRIS) provides an in-situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies. We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003) and that based on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005) yielded accuracy better than 0.06‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers differed by 9.44 ± 1.65‰ (mean ± 1 standard deviation of hourly values) before calibration and agreed to within -0.02 ± 0.18‰ after properly calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis resulting in a much larger difference of 2.44‰ for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research.

  12. Evaluating calibration strategies for isotope ratio infrared spectroscopy for atmospheric 13CO2 / 12CO2 measurement

    NASA Astrophysics Data System (ADS)

    Wen, X.-F.; Meng, Y.; Zhang, X.-Y.; Sun, X.-M.; Lee, X.

    2013-06-01

    Isotope ratio infrared spectroscopy (IRIS) provides an in situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies. We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003) and on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005) yielded accuracy better than 0.06‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers agreed to within -0.02 ± 0.18‰ after proper calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis, resulting in a much larger difference of 2.44‰ for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research.

  13. A new concept for sensitive in situ stable isotope ratio infrared spectroscopy based on sample modulation.

    PubMed

    Werle, Peter; Dyroff, Christoph; Zahn, Andreas; Mazzinghi, Piero; D'amato, Francesco

    2005-12-01

    Diode-laser absorption spectroscopy finds increasing applications in the emerging field of stable isotope research. To meet the requirements of the water isotopes measurement challenge in environmental research, ways have to be found to cope with the present limitations of spectroscopic systems. In this article, we discuss an approach based on the Stark effect in molecular spectra to reduce the influence of time-dependent, unwanted background structures generally superimposed on the desired signal from the spectral feature under investigation. A road map to high-sensitivity isotopic ratio measurements of water isotopes is presented. On the basis of an Allan Variance analysis of measured data, the detection limits have been calculated as a function of the integration time. To achieve the required optical density of about 6 x 10(-7) for H(2)(17)O measurements, the duty cycle has to be optimized and the implementation of a sample modulation within an optical multipass cell is a promising approach to increase the stability of spectroscopic instrumentation required for ecosystem research and airborne atmospheric platforms. PMID:16543188

  14. Evaluation of infrared spectra analyses using a likelihood ratio approach: A practical example of spray paint examination.

    PubMed

    Muehlethaler, Cyril; Massonnet, Geneviève; Hicks, Tacha

    2016-03-01

    Depending on the forensic disciplines and on the analytical techniques used, Bayesian methods of evaluation have been applied both as a two-step approach (first comparison, then evaluation) and as a continuous approach (comparison and evaluation in one step). However in order to use the continuous approach, the measurements have to be reliably summarized as a numerical value linked to the property of interest, which occurrence can be determined (e.g., refractive index measurement of glass samples). For paint traces analyzed by Fourier transform infrared spectroscopy (FTIR) however, the statistical comparison of the spectra is generally done by a similarity measure (e.g., Pearson correlation, Euclidean distance). Although useful, these measures cannot be directly associated to frequencies of occurrence of the chemical composition (binders, extenders, pigments). The continuous approach as described above is not possible, and a two-step evaluation, 1) comparison of the spectra and 2) evaluation of the results, is therefore the common practice reported in most of the laboratories. Derived from a practical question that arose during casework, a way of integrating the similarity measure between spectra into a continuous likelihood ratio formula was explored. This article proposes the use of a likelihood ratio approach with the similarity measure of infrared spectra of spray paints based on distributions of sub-populations given by the color and composition of spray paint cans. Taking into account not only the rarity of paint composition, but also the "quality" of the analytical match provides a more balanced evaluation given source or activity level propositions. We will demonstrate also that a joint statistical-expertal methodology allows for a more transparent evaluation of the results and makes a better use of current knowledge. PMID:26976462

  15. ``Smart'' theranostic lanthanide nanoprobes with simultaneous up-conversion fluorescence and tunable T1-T2 magnetic resonance imaging contrast and near-infrared activated photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Das, Gautom Kumar; Vijayaragavan, Vimalan; Xu, Qing Chi; Padmanabhan, Parasuraman; Bhakoo, Kishore K.; Tamil Selvan, Subramanian; Tan, Timothy Thatt Yang

    2014-10-01

    The current work reports a type of ``smart'' lanthanide-based theranostic nanoprobe, NaDyF4:Yb3+/NaGdF4:Yb3+,Er3+, which is able to circumvent the up-converting poisoning effect of Dy3+ ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent.The current work reports a type of ``smart'' lanthanide-based theranostic nanoprobe, NaDyF4:Yb3+/NaGdF4:Yb3+,Er3+, which is able to circumvent the up-converting poisoning effect of Dy3+ ions to give efficient near infrared (980 nm) triggered up-conversion fluorescence, and offers not only excellent dark T2-weighted MR contrast but also tunable bright and T1-weighted MR contrast properties. Due to the efficient up-converted energy transfer from the nanocrystals to chlorin e6 (Ce6) photosensitizers loaded onto the nanocrystals, cytotoxic singlet oxygen was generated and photodynamic therapy was demonstrated. Therefore, the current multifunctional nanocrystals could be potentially useful in various image-guided diagnoses where bright or dark MRI contrast could be selectively tuned to optimize image quality, but also as an efficient and more penetrative near-infrared activated photodynamic therapy agent. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01717j

  16. Reducing and correcting for contamination of ecosystem water stable isotopes measured by isotope ratio infrared spectroscopy.

    PubMed

    Schmidt, Markus; Maseyk, Kadmiel; Lett, Céline; Biron, Philippe; Richard, Patricia; Bariac, Thierry; Seibt, Ulli

    2012-01-30

    Concern exists about the suitability of laser spectroscopic instruments for the measurement of the (18)O/(16)O and (2)H/(1)H values of liquid samples other than pure water. It is possible to derive erroneous isotope values due to optical interference by certain organic compounds, including some commonly present in ecosystem-derived samples such as leaf or soil waters. Here we investigated the reliability of wavelength-scanned cavity ring-down spectroscopy (CRDS) (18)O/(16)O and (2)H/(1)H measurements from a range of ecosystem-derived waters, through comparison with isotope ratio mass spectrometry (IRMS). We tested the residual of the spectral fit S(r) calculated by the CRDS instrument as a means to quantify the difference between the CRDS and IRMS δ-values. There was very good overall agreement between the CRDS and IRMS values for both isotopes, but differences of up to 2.3‰ (δ(18)O values) and 23‰ (δ(2)H values) were observed in leaf water extracts from Citrus limon and Alnus cordata. The S(r) statistic successfully detected contaminated samples. Treatment of Citrus leaf water with activated charcoal reduced, but did not eliminate, δ(2)H(CRDS) - δ(2)H(IRMS) linearly for the tested range of 0-20% charcoal. The effect of distillation temperature on the degree of contamination was large, particularly for δ(2)H values but variable, resulting in positive, negative or no correlation with distillation temperature. S(r) and δ(CRDS) - δ(IRMS) were highly correlated, in particular for δ(2)H values, across the range of samples that we tested, indicating the potential to use this relationship to correct the δ-values of contaminated plant water extracts. We also examined the sensitivity of the CRDS system to changes in the temperature of its operating environment. We found that temperature changes ≥4 °C for δ(18)O values and ≥10 °C for δ(2)H values resulted in errors larger than the CRDS precision for the respective isotopes and advise the use of such

  17. Comparing CO2 flux data from eddy covariance methods with bowen ratio energy balance methods from contrasting soil management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measuring CO2 fluxes from contrasting soil management practices is important for understanding the role of agriculture in source-sink relationship with CO2 flux. There are several micrometeorological methods for measuring CO2 emissions, however all are expensive and thus do not easily lend themselve...

  18. Performance of isotope ratio infrared spectroscopy (IRIS) for analyzing waters containing organic contaminants: Problems and solutions (Invited)

    NASA Astrophysics Data System (ADS)

    West, A. G.; Goldsmith, G. R.; Dawson, T. E.

    2010-12-01

    The development of isotope ratio infrared spectroscopy (IRIS) for simultaneous δ2H and δ18O analysis of liquid water samples shows much potential for affordable, simple and potentially portable isotopic analyses. IRIS has been shown to be comparable in precision and accuracy to isotope ratio mass spectrometry (IRMS) when analyzing pure water samples. However, recent studies have shown that organic contaminants in analyzed water samples may interfere with the spectroscopy leading to errors of considerable magnitude in the reported stable isotope data. Many environmental, biological and forensic studies require analyses of water containing organic contaminants in some form, yet our current methods of removing organic contaminants prior to analysis appear inadequate for IRIS. Treated plant water extracts analyzed by IRIS showed deviations as large as 35‰ (δ2H) and 11.8‰ (δ18O) from the IRMS value, indicating that trace amounts of contaminants were sufficient to disrupt IRIS analyses. However, not all organic contaminants negatively influence IRIS. For such samples, IRIS presents a labour saving method relative to IRMS. Prior to widespread use in the environmental, biological and forensic sciences, a means of obtaining reliable data from IRIS needs to be demonstrated. One approach is to use instrument-based software to flag potentially problematic spectra and output a corrected isotope value based on analysis of the spectra. We evaluate this approach on two IRIS systems and discuss the way forward for ensuring accurate stable isotope data using IRIS.

  19. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  20. Spectral analysis software improves confidence in plant and soil water stable isotope analyses performed by isotope ratio infrared spectroscopy (IRIS).

    PubMed

    West, A G; Goldsmith, G R; Matimati, I; Dawson, T E

    2011-08-30

    Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be

  1. Near-Infrared Emitters: Stepwise Assembly of Two Heteropolynuclear Clusters with Tunable Ag(I):Zn(II) Ratio.

    PubMed

    Wang, Zhi; Zhuang, Gui-Lin; Deng, Yong-Kai; Feng, Zhen-Yu; Cao, Zhao-Zhen; Kurmoo, Mohamedally; Tung, Chen-Ho; Sun, Di

    2016-05-16

    Two 3d-4d heteropolynuclear clusters with Ag-Zn ratios of 9:2 and 9:4 were stepwise constructed from a robust nonanuclear silver cluster. Their crystal structures consist of a common bucket-shaped [Ag9(mba)9](9-) (H2mba = 2-mercaptobenzoic acid) core with different numbers of Zn(II) connected by different exo-oriented carboxylates. Most fascinating is the observation of emission (∼703 nm) in the near-infrared (NIR) region at 300 K that may be compared to the related Ag9Zn3 cluster with aliphatic polyamine as auxiliary ligand that emits from the visible (∼580 nm). The shift is associated with the change of ligand field of the 2,2'-bipyridine. The emission intensity and lifetime were dramatically enhanced along with the slight bathochromic shift upon cooling from 300 K to 80 K. The results raise two significant issues: (a) the structural and electronic effects of the secondary metal binding to the metalloligand and the factors influencing the heteropolynuclear cluster assembly and (b) the use of NIR fluorescence, introduced by integrating two luminophores into one heteropolynuclear entity, in detecting free-moving zinc in biological systems both in vivo and in vitro. PMID:27110839

  2. Multispectral measurement of contrast in tissue-mimicking phantoms in near-infrared spectral range of 650 to 1600 nm

    PubMed Central

    Salo, Daniel; Zhang, Hairong; Kim, David M.; Berezin, Mikhail Y.

    2014-01-01

    Abstract. In order to identify the optimal imaging conditions for the highest spatial contrast in biological tissue, we explored the properties of a tissue-mimicking phantom as a function of the wavelengths in a broad range of near-infrared spectra (650 to 1600 nm). Our customized multispectral hardware, which featured a scanning transmission microscope and imaging spectrographs equipped with silicon and InGaAs charge-coupled diode array detectors, allowed for direct comparison of the Michelson contrast obtained from a phantom composed of a honeycomb grid, Intralipid, and India ink. The measured contrast depended on the size of the grid, luminance, and the wavelength of measurements. We demonstrated that at low thickness of the phantom, a reasonable contrast of the objects can be achieved at any wavelength between 700 and 1400 nm and between 1500 and 1600 nm. At larger thicknesses, such contrast can be achieved mostly between 1200 and 1350 nm. These results suggest that distinguishing biological features in deep tissue and developing contrast agents for in vivo may benefit from imaging in this spectral range. PMID:25104414

  3. Processes affecting oxygen isotope ratios of atmospheric and ecosystem sulfate in two contrasting forest catchments in Central Europe

    SciTech Connect

    Martin Novak; Myron J. Mitchell; Iva Jackova; Frantisek Buzek; Jana Schweigstillova; Lucie Erbanova; Richard Prikryl; Daniela Fottova

    2007-02-15

    Sulfate aerosols are harmful as respirable particles. They also play a role as cloud condensation nuclei and have radiative effects on global climate. A combination of {delta}{sup 18}O-SO{sub 4} data with catchment sulfur mass balances was used to constrain processes affecting S cycling in the atmosphere and spruce forests of the Czech Republic. Extremely high S fluxes via spruce throughfall and runoff were measured at Jezeri (49 and 80 kg S ha{sup -1} yr{sup -1}, respectively). The second catchment, Na Lizu, was 10 times less polluted. In both catchments, {delta}{sup 18}O-SO{sub 4} decreased in the following order: open-area precipitation {gt} throughfall {gt} runoff. The 180-SO{sub 4} values of throughfall exhibited a seasonal pattern at both sites, with maxima in summer and minima in winter. This seasonal pattern paralleled {delta}{sup 18}O-H{sub 2}O values, which were offset by -18{per_thousand}. Sulfate in throughfall was predominantly formed by heterogeneous (aqueous) oxidation of SO{sub 2}. Wet-deposited sulfate in an open area did not show systematic {delta}{sup 18}O-SO{sub 4} trends, suggesting formation by homogeneous (gaseous) oxidation and/or transport from large distances. The percentage of incoming S that is organically cycled in soil was similar under the high and the low pollution. High-temperature {sup 18}O-rich sulfate was not detected, which contrasts with North American industrial sites. 29 refs., 4 figs., 3 tabs.

  4. Monitoring CO2 concentration and δ13C in an underground cavity using a commercial isotope ratio infrared spectrometer

    NASA Astrophysics Data System (ADS)

    Guillon, Sophie; Agrinier, Pierre; Pili, Éric

    2015-04-01

    CO2 stable carbon isotopes are very attractive in environmental research to investigate both natural and anthropogenic carbon sources. Laser-based isotope ratio infrared spectrometers (IRIS) allow in situ continuous monitoring of CO2 isotopes, and therefore they have a potential for unprecedented understanding of carbon sources and dynamics with a high temporal resolution. Here we present the performance assessment of a commercial IRIS analyzer, including the measurement setup and the data processing scheme that we used. Even if the analyzer performs 1-Hz measurements, an integration time of the order of 1 h is commonly needed to obtain acceptable precision for δ13C. The main sources of uncertainty on δ13C come from the concentration dependence and from the temporal instability of the analyzer. The method is applied to the in situ monitoring of the CO2 carbon isotopes in an underground cavity (Roselend Natural Laboratory, France) during several months. On a weekly timescale, the temporal variability of CO2 is dominated by transient contamination by human breath. Discarding these anthropogenic contaminations, CO2 and δ13C backgrounds do not show diurnal or seasonal fluctuations. A CO2 flux released into the tunnel by the surrounding rocks is measured. The carbon isotope composition of this CO2, identified with a Keeling plot, is consistent with a main production by microbial respiration and a minor production from weathering of carbonate minerals. The presented instrument and application study are relevant to cave monitoring, whether to understand CO2 dynamics in visited and/or painted caves for preservation purposes or to understand paleoclimate recording in speleothems.

  5. Airborne ultraviolet imaging system for oil slick surveillance: oil-seawater contrast, imaging concept, signal-to-noise ratio, optical design, and optomechanical model.

    PubMed

    Shi, Zhenhua; Yu, Lei; Cao, Diansheng; Wu, Qingwen; Yu, Xiangyang; Lin, Guanyu

    2015-09-01

    The airborne ultraviolet imaging system, which assesses oil slick areas better than visible and infrared optical systems, was designed to monitor and track oil slicks in coastal regions. A model was built to achieve the upwelling radiance distribution of oil-covered sea and clean seawater, based on the radiance transfer software. With this model, the oil-seawater contrast, which affects the detection of oil-covered coastal areas, was obtained. The oil-seawater contrast, fundamental imaging concept, analog calculation of SNR, optical design, and optomechanical configuration of the airborne ultraviolet imaging system are illustrated in this paper. The study of an airborne ultraviolet imaging system with F-number 3.4 and a 40° field of view (FOV) in near ultraviolet channel (0.32-0.38 μm) was illustrated and better imaging quality was achieved. The ground sample distance (GSD) is from 0.35 to 0.7 m with flight height ranges from 0.5 to 1 km. Comparisons of detailed characteristics of the airborne ultraviolet imaging system with the corresponding characteristics of previous ultraviolet systems were tabulated, and these comparisons showed that this system can achieve a wide FOV and a relative high SNR. A virtual mechanical prototype and tolerances analysis are illustrated in this paper to verify the performance of fabrication and assembly of the ultraviolet system. PMID:26368888

  6. Use of YbIII-centered near-infrared (NIR) luminescence to determine the hydration state of a 3,2-HOPO-based MRI contrast agent.

    PubMed

    Moore, Evan G; Seitz, Michael; Raymond, Kenneth N

    2008-10-01

    The synthesis, structure, and characterization of a [Yb(Tren-Me-3,2-HOPO)(H 2O) 2] complex are reported. As a result of its Yb (III) emission in the near-infrared region, sensitized by the Me-3,2-HOPO chromophore, this complex can be utilized for the first time to determine the hydration state, q, via the luminescence lifetimes and hence the solution structure of these Me-3,2-HOPO-type ligands, which have attracted significant interest in complex with Gd (III) as possible next-generation magnetic resonance imaging contrast agents. PMID:18729353

  7. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent

    PubMed Central

    Moore, Evan G.; Seitz, Michael

    2011-01-01

    The synthesis, structure, and characterization of a [Yb(Tren-Me-3,2-HOPO)(H2O)2] complex are reported. As a result of its Yb(III) emission in the Near Infra-Red (NIR) region, sensitized by the Me-3,2-HOPO chromophore, this complex can be utilized for the first time to determine the hydration state, q, via the luminescence lifetimes and hence the solution structure of these Me-3,2-HOPO type ligands which have attracted significant interest in complex with Gd(III) as possible next generation magnetic resonance imaging contrast agents (MRI-CA). PMID:18729353

  8. DESIGN, FABRICATION, ASSEMBLY AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF REACTION CHAMBER TEMPERATURE

    SciTech Connect

    Tom Leininger

    2001-03-31

    Reliable measurement of gasifier reaction chamber temperature is important for the proper operation of slagging, entrained-flow gasification processes. Historically, thermocouples have been used as the main measurement technique, with the temperature inferred from syngas methane concentration being used as a backup measurement. While these have been sufficient for plant operation in many cases, both techniques suffer from limitations. The response time of methane measurements is too slow to detect rapid upset conditions, and thermocouples are subject to long-term drift, as well as slag attack, which eventually leads to failure of the thermocouple. Texaco's Montebello Technology Center (MTC) has developed an infrared ratio pyrometer system for measuring gasifier reaction chamber temperature. This system has a faster response time than both methane and thermocouples, and has been demonstrated to provide reliable temperature measurements for longer periods of time when compared to thermocouples installed in the same MTC gasifier. In addition, the system can be applied to commercial gasifiers without any significant scale-up issues. The major equipment items, the purge system, and the safety shutdown system in a commercial plant are essentially identical to the prototypes at MTC. The desired result of this DOE program is ''a bench-scale prototype, either assembled or with critical components (laboratory) tested in a convincing manner.'' The prototype of the pyrometer system (including gasifier optical access port) that was designed, assembled and tested for this program, has had previous prototypes that have been built and successfully tested under actual coal and coke gasification conditions in three pilot units at MTC. It was the intent of the work performed under the auspices of this program to review and update the existing design, and to fabricate and bench test an updated system that can be field tested in one or more commercial gasifiers during a follow on phase

  9. Self-assembled dual-modality contrast agents for non-invasive stem cell tracking via near-infrared fluorescence and magnetic resonance imaging.

    PubMed

    Liu, Hong; Tan, Yan; Xie, Lisi; Yang, Lei; Zhao, Jing; Bai, Jingxuan; Huang, Ping; Zhan, Wugen; Wan, Qian; Zou, Chao; Han, Yali; Wang, Zhiyong

    2016-09-15

    Stem cells hold great promise for treating various diseases. However, one of the main drawbacks of stem cell therapy is the lack of non-invasive image-tracking technologies. Although magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging have been employed to analyse cellular and subcellular events via the assistance of contrast agents, the sensitivity and temporal resolution of MRI and the spatial resolution of NIRF are still shortcomings. In this study, superparamagnetic iron oxide nanocrystals and IR-780 dyes were co-encapsulated in stearic acid-modified polyethylenimine to form a dual-modality contrast agent with nano-size and positive charge. These resulting agents efficiently labelled stem cells and did not influence the cellular viability and differentiation. Moreover, the labelled cells showed the advantages of dual-modality imaging in vivo. PMID:27299677

  10. Aspect ratio-related three-photon absorption and mechanism of α-FeOOH nanorods in the near-infrared

    NASA Astrophysics Data System (ADS)

    Zhu, Baohua; Wang, Fangfang; Wang, Chong; Cao, Yawan; Guo, Lijun; Zhang, Jiayu; Gu, Yuzong

    2016-07-01

    Tuning a semiconductor nanomaterial with large three-photon absorption (3PA) cross section in the near infrared and investigating the relationship between the nanostructure and nonlinear optical properties is a challenging topic, which is of significance in potential applications. Here, we report the aspect ratio-related 3PA response of α-FeOOH nanorods (NRs) in the near infrared. Large 3PA cross section at room temperature is achieved as high as ~10‑77 cm6 s2 photon‑2 when the distribution of photo-induced and intrinsic surface polarization charges of excitons to both ends of NRs is tuned through the aspect ratio, yielding total enhancement more than three times larger than that of NRs with 12.1 nm diameter.

  11. Aspect ratio-related three-photon absorption and mechanism of α-FeOOH nanorods in the near-infrared.

    PubMed

    Zhu, Baohua; Wang, Fangfang; Wang, Chong; Cao, Yawan; Guo, Lijun; Zhang, Jiayu; Gu, Yuzong

    2016-07-20

    Tuning a semiconductor nanomaterial with large three-photon absorption (3PA) cross section in the near infrared and investigating the relationship between the nanostructure and nonlinear optical properties is a challenging topic, which is of significance in potential applications. Here, we report the aspect ratio-related 3PA response of α-FeOOH nanorods (NRs) in the near infrared. Large 3PA cross section at room temperature is achieved as high as ~10(-77) cm(6) s(2) photon(-2) when the distribution of photo-induced and intrinsic surface polarization charges of excitons to both ends of NRs is tuned through the aspect ratio, yielding total enhancement more than three times larger than that of NRs with 12.1 nm diameter. PMID:27218307

  12. Cyanine dyes as contrast agents for near-infrared imaging in vivo: acute tolerance, pharmacokinetics, and fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Ebert, Bernd; Riefke, Björn; Sukowski, Uwe; Licha, Kai

    2011-06-01

    We compare pharmacokinetic, tolerance, and imaging properties of two near-IR contrast agents, indocyanine green (ICG) and 1,1'-bis-(4-sulfobutyl) indotricarbocyanine-5,5'-dicarboxylic acid diglucamide monosodium salt (SIDAG). ICG is a clinically approved imaging agent, and its derivative SIDAG is a more hydrophilic counterpart that has recently shown promising imaging properties in preclinical studies. The rather lipophilic ICG has a very short plasma half-life, thus limiting the time available to image body regions during its vascular circulation (e.g., the breast in optical mammography where scanning over several minutes is required). In order to change the physicochemical properties of the indotricarbocyanine dye backbone, several derivatives were synthesized with increasing hydrophilicity. The most hydrophilic dye SIDAG is selected for further biological characterization. The acute tolerance of SIDAG in mice is increased up to 60-fold compared to ICG. Contrary to ICG, the pharmacokinetic properties of SIDAG are shifted toward renal elimination, caused by the high hydrophilicity of the molecule. N-Nitrosomethylurea (NMU)-induced rat breast carcinomas are clearly demarcated, both immediately and 24 h after intravenous administration of SIDAG, whereas ICG shows a weak tumor contrast under the same conditions. Our findings demonstrate that SIDAG is a high potential contrast agent for optical imaging, which could increase the sensitivity for detection of inflamed regions and tumors.

  13. Differential Tuning of the Electron Transfer Parameters in 1,3,5-Triarylpyrazolines: A Rational Design Approach for Optimizing the Contrast Ratio of Fluorescent Probes

    PubMed Central

    Cody, John; Mandal, Subrata; Yang, Liuchun; Fahrni, Christoph J.

    2010-01-01

    A large class of cation-responsive fluorescent sensors utilizes a donor-spacer-acceptor (D-A) molecular framework that can modulate the fluorescence emission intensity through a fast photoinduced intramolecular electron transfer (PET) process. The emission enhancement upon binding of the analyte defines the contrast ratio of the probe, a key property that is particularly relevant in fluorescence microscopy imaging applications. Due to their unusual electronic structure, 1,3,5-triaryl-pyrazoline fluorophores allow for the differential tuning of the excited state energy ΔE00 and the fluorophore acceptor potential E(A/A−), both of which are critical parameters that define the ET thermodynamics and thus the contrast ratio. By systematically varying the number and attachment positions of fluoro-substituents on the fluorophore π-system, ΔE00 can be adjusted over a broad range (0.4 eV) without significantly altering the acceptor potential E(A/A−). Experimentally measured D-A coupling and reorganization energies were used to draw a potential map for identifying the optimal ET driving force that is expected to give a maximum fluorescence enhancement for a given change in donor potential upon binding of the analyte. The rational design strategy was tested by optimizing the fluorescence response of a pH sensitive probe, thus yielding a maximum emission enhancement factor of 400 upon acidification. Furthermore, quantum chemical calculations were used to reproduce the experimental trends of reduction potentials, excited state energies, and ET driving forces within the framework of linear free energy relationships (LFER). Such LFERs should be suitable to semi-empirically predict ET driving forces with an average unsigned error of 0.03 eV, consequently allowing for the computational prescreening of substituent combinations to best match the donor potential of a given cation receptor. Within the scaffold of the triarylpyrazoline platform, the outlined differential tuning of

  14. Laser-based K α X-ray emission characterization using a high contrast ratio and high-power laser system

    NASA Astrophysics Data System (ADS)

    Fourmaux, S.; Kieffer, J. C.

    2016-06-01

    We characterized a laser-based K_α X-ray source produced onto a Mo solid target. We used a laser system with a high laser pulse contrast ratio (LPCR) and an instantaneous power ˜30 TW. We investigated simultaneously the K_α X-ray conversion efficiency, the X-ray source size, and the proton front surface emission. We found a high K_α X-ray conversion efficiency up to 2× 10^{-4} associated with an X-ray source size only ˜1.8 times larger than the laser focal spot for the highest intensities. We found that using a high LPCR laser pulse with 245 mJ per pulse is of interest to develop a laser-based X-ray imaging system as it can combine a high conversion efficiency with a small increase in the X-ray source size compared to the laser focal spot.

  15. FAR-INFRARED LINE DEFICITS IN GALAXIES WITH EXTREME L{sub FIR}/M{sub H{sub 2}} RATIOS

    SciTech Connect

    Gracia-Carpio, J.; Sturm, E.; Hailey-Dunsheath, S.; Contursi, A.; Poglitsch, A.; Genzel, R.; Davies, R.; Feuchtgruber, H.; De Jong, J. A.; Lutz, D.; Tacconi, L. J.; Fischer, J.; Gonzalez-Alfonso, E.; Sternberg, A.; Verma, A.; Christopher, N.

    2011-02-10

    We report initial results from the far-infrared fine structure line observations of a sample of 44 local starbursts, Seyfert galaxies, and infrared luminous galaxies obtained with the PACS spectrometer on board Herschel. We show that the ratio between the far-infrared luminosity and the molecular gas mass, L{sub FIR}/M{sub H{sub 2}}, is a much better proxy for the relative brightness of the far-infrared lines than L{sub FIR} alone. Galaxies with high L{sub FIR}/M{sub H{sub 2}} ratios tend to have weaker fine structure lines relative to their far-infrared continuum than galaxies with L{sub FIR}/M{sub H{sub 2}} , or approx. 80 L{sub {circle_dot}}M{sub {circle_dot}}{sup -1}. A deficit of the [C II] 158 {mu}m line relative to L{sub FIR} was previously found with the Infrared Space Observatory, but now we show for the first time that this is a general aspect of all far-infrared fine structure lines, regardless of their origin in the ionized or neutral phase of the interstellar medium. The L{sub FIR}/M{sub H{sub 2}} value where these line deficits start to manifest is similar to the limit that separates between the two modes of star formation recently found in galaxies on the basis of studies of their gas-star formation relations. Our finding that the properties of the interstellar medium are also significantly different in these regimes provides independent support for the different star-forming relations in normal disk galaxies and major merger systems. We use the spectral synthesis code Cloudy to model the emission of the lines. The expected increase of the ionization parameter with L{sub FIR}/M{sub H{sub 2}} can simultaneously explain the line deficits in the [C II], [N II], and [O I] lines.

  16. Characterizing accuracy of total hemoglobin recovery using contrast-detail analysis in 3D image-guided near infrared spectroscopy with the boundary element method

    PubMed Central

    Ghadyani, Hamid R.; Srinivasan, Subhadra; Pogue, Brian W.; Paulsen, Keith D.

    2010-01-01

    The quantification of total hemoglobin concentration (HbT) obtained from multi-modality image-guided near infrared spectroscopy (IG-NIRS) was characterized using the boundary element method (BEM) for 3D image reconstruction. Multi-modality IG-NIRS systems use a priori information to guide the reconstruction process. While this has been shown to improve resolution, the effect on quantitative accuracy is unclear. Here, through systematic contrast-detail analysis, the fidelity of IG-NIRS in quantifying HbT was examined using 3D simulations. These simulations show that HbT could be recovered for medium sized (20mm in 100mm total diameter) spherical inclusions with an average error of 15%, for the physiologically relevant situation of 2:1 or higher contrast between background and inclusion. Using partial 3D volume meshes to reduce the ill-posed nature of the image reconstruction, inclusions as small as 14mm could be accurately quantified with less than 15% error, for contrasts of 1.5 or higher. This suggests that 3D IG-NIRS provides quantitatively accurate results for sizes seen early in treatment cycle of patients undergoing neoadjuvant chemotherapy when the tumors are larger than 30mm. PMID:20720975

  17. 3D laser-written silica glass step-index high-contrast waveguides for the 3.5 μm mid-infrared range.

    PubMed

    Martínez, Javier; Ródenas, Airán; Fernandez, Toney; Vázquez de Aldana, Javier R; Thomson, Robert R; Aguiló, Magdalena; Kar, Ajoy K; Solis, Javier; Díaz, Francesc

    2015-12-15

    We report on the direct laser fabrication of step-index waveguides in fused silica substrates for operation in the 3.5 μm mid-infrared wavelength range. We demonstrate core-cladding index contrasts of 0.7% at 3.39 μm and propagation losses of 1.3 (6.5) dB/cm at 3.39 (3.68) μm, close to the intrinsic losses of the glass. We also report on the existence of three different laser modified SiO₂ glass volumes, their different micro-Raman spectra, and their different temperature-dependent populations of color centers, tentatively clarifying the SiO₂ lattice changes that are related to the large index changes. PMID:26670520

  18. In-lab ALOHA mid-infrared up-conversion interferometer with high fringe contrast @λ = 3.39 μm

    NASA Astrophysics Data System (ADS)

    Szemendera, L.; Darré, P.; Baudoin, R.; Grossard, L.; Delage, L.; Herrmann, H.; Silberhorn, C.; Reynaud, F.

    2016-04-01

    We report on the implementation of a mid-infrared (MIR) interferometer prototype for furthermore application in the framework of high-resolution imaging in astronomy. This paper demonstrates the possibility to extend to the L band our experimental study performed on the up-conversion interferometer in H band. This in-laboratory preliminary experiment allowed us to get the first fringes with the MIR Astronomical Light Optical Hybrid Analysis (ALOHA) @3.39 μm up-conversion interferometer with a bright quasi monochromatic source (HeNe 3.39 μm). A stable contrast greater than 98 per cent has been reached. This opens the possibility to propose an alternative instrument for the demanding domain of high resolution imaging in the MIR domain.

  19. Real-time visualization of low contrast targets from high-dynamic range infrared images based on temporal digital detail enhancement filter

    NASA Astrophysics Data System (ADS)

    Garcia, Frederic; Schockaert, Cedric; Mirbach, Bruno

    2015-11-01

    An image detail enhancement method to effectively visualize low contrast targets in high-dynamic range (HDR) infrared (IR) images is presented regardless of the dynamic range width. In general, high temperature dynamics from real-world scenes used to be encoded in a 12 or 14 bits IR image. However, the limitations of the human visual perception, from which no more than 128 shades of gray are distinguishable, and the 8-bit working range of common display devices make necessary an effective 12/14 bits HDR mapping into the 8-bit data representation. To do so, we propose to independently treat the base and detail image components that result from splitting the IR image using two dedicated guided filters. We also introduce a plausibility mask from which those regions that are prominent to present noise are accurately defined to be explicitly tackled to avoid noise amplification. The final 8-bit data representation results from the combination of the processed detail and base image components and its mapping to the 8-bit domain using an adaptive histogram-based projection approach. The limits of the histogram are accommodated through time in order to avoid global brightness fluctuations between frames. The experimental evaluation shows that the proposed noise-aware approach preserves low contrast details with an overall contrast enhancement of the image. A comparison with widely used HDR mapping approaches and runtime analysis is also provided. Furthermore, the proposed mathematical formulation enables a real-time adjustment of the global contrast and brightness, letting the operator adapt to the visualization display device without nondesirable artifacts.

  20. Multivariate determination of 13CO2/12CO2 ratios in exhaled mouse breath with mid-infrared hollow waveguide gas sensors.

    PubMed

    Seichter, Felicia; Wilk, Andreas; Wörle, Katharina; Kim, Seong-Soo; Vogt, Josef A; Wachter, Ulrich; Radermacher, Peter; Mizaikoff, Boris

    2013-05-01

    The (12)CO2/(13)CO2 isotope ratio is a well-known marker in breath for a variety of biochemical processes and enables monitoring, e.g., of the glucose metabolism during sepsis. Using animal models-here, at a mouse intensive care unit-the simultaneous determination of (12)CO2 and (13)CO2 within small volumes of mouse breath was enabled by coupling a novel low-volume hollow waveguide gas cell to a compact Fourier transform infrared spectrometer combined with multivariate data evaluation based on partial least squares regression along with optimized data preprocessing routines. PMID:23503745

  1. The Micro-Angiographic Fluoroscope (MAF) in High Definition (HD) Mode for Improved Contrast-to-Noise Ratio and Resolution in Fluoroscopy and Roadmapping

    PubMed Central

    Panse, Ashish; Ionita, C. N.; Wang, W.; Natarajan, S. K.; Jain, A.; Bednarek, D. R.; Rudin, S.

    2011-01-01

    During image guided interventional procedures, superior resolution and image quality is critically important. Operating the MAF in the new High Definition (HD) fluoroscopy mode provides high resolution and increased contrast-to-noise ratio. The MAF has a CCD camera and a 300 micron cesium iodide x-ray convertor phosphor coupled to a light image intensifier (LII) through a fiber-optic taper. The MAF captures 1024 × 1024 pixels with an effective pixel size of 35 microns, and is capable of real-time imaging at 30 fps. The HD mode uses the advantages of higher exposure along with a small focal spot effectively improving the contrast-to-noise ratio (CNR) and the spatial resolution. The Control Acquisition Processing and Image Display System (CAPIDS) software for the MAF controls the LII gain. The interventionalist can select either fluoroscopic or angiographic modes using the two standard foot pedals. When improved image quality is needed and the angiography footpedal is used for HD mode, the x-ray machine will operate at a preset higher exposure rate using a small focal spot, while the CAPIDS will automatically adjust the LII gain to achieve proper image brightness. HD mode fluoroscopy and roadmapping are thus achieved conveniently during the interventional procedure. For CNR and resolution evaluation we used a bar phantom with images taken in HD mode with both the MAF and a Flat Panel Detector (FPD). It was seen that the FPD could not resolve more than 2.8 lp/mm whereas the MAF could resolve more than 5 lp/mm. The CNR of the MAF was better than that of the FPD by 60% at lower frequencies and by 600% at the Nyquist frequency of the FPD. The HD mode has become the preferred mode during animal model interventions because it enables detailed features of endovascular devices such as stent struts to be visualized clearly for the first time. Clinical testing of the MAF in HD mode is imminent. PMID:21766062

  2. The Micro-Angiographic Fluoroscope (MAF) in High Definition (HD) Mode for Improved Contrast-to-Noise Ratio and Resolution in Fluoroscopy and Roadmapping.

    PubMed

    Panse, Ashish; Ionita, C N; Wang, W; Natarajan, S K; Jain, A; Bednarek, D R; Rudin, S

    2010-10-30

    During image guided interventional procedures, superior resolution and image quality is critically important. Operating the MAF in the new High Definition (HD) fluoroscopy mode provides high resolution and increased contrast-to-noise ratio. The MAF has a CCD camera and a 300 micron cesium iodide x-ray convertor phosphor coupled to a light image intensifier (LII) through a fiber-optic taper. The MAF captures 1024 × 1024 pixels with an effective pixel size of 35 microns, and is capable of real-time imaging at 30 fps. The HD mode uses the advantages of higher exposure along with a small focal spot effectively improving the contrast-to-noise ratio (CNR) and the spatial resolution. The Control Acquisition Processing and Image Display System (CAPIDS) software for the MAF controls the LII gain. The interventionalist can select either fluoroscopic or angiographic modes using the two standard foot pedals. When improved image quality is needed and the angiography footpedal is used for HD mode, the x-ray machine will operate at a preset higher exposure rate using a small focal spot, while the CAPIDS will automatically adjust the LII gain to achieve proper image brightness. HD mode fluoroscopy and roadmapping are thus achieved conveniently during the interventional procedure. For CNR and resolution evaluation we used a bar phantom with images taken in HD mode with both the MAF and a Flat Panel Detector (FPD). It was seen that the FPD could not resolve more than 2.8 lp/mm whereas the MAF could resolve more than 5 lp/mm. The CNR of the MAF was better than that of the FPD by 60% at lower frequencies and by 600% at the Nyquist frequency of the FPD. The HD mode has become the preferred mode during animal model interventions because it enables detailed features of endovascular devices such as stent struts to be visualized clearly for the first time. Clinical testing of the MAF in HD mode is imminent. PMID:21766062

  3. Contrasted enzymatic cocktails reveal the importance of cellulases and hemicellulases activity ratios for the hydrolysis of cellulose in presence of xylans.

    PubMed

    Dondelinger, Eve; Aubry, Nathalie; Ben Chaabane, Fadhel; Cohen, Céline; Tayeb, Jean; Rémond, Caroline

    2016-03-01

    Various enzymatic cocktails were produced from two Trichoderma reesei strains, a cellulase hyperproducer strain and a strain with β-glucosidase activity overexpression. By using various carbon sources (lactose, glucose, xylose, hemicellulosic hydrolysate) for strains growth, contrasted enzymatic activities were obtained. The enzymatic cocktails presented various levels of efficiency for the hydrolysis of cellulose Avicel into glucose, in presence of xylans, or not. These latter were also hydrolyzed with different extents according to cocktails. The most efficient cocktails (TR1 and TR3) on Avicel were richer in filter paper activity (FPU) and presented a low ratio FPU/β-glucosidase activity. Cocktails TR2 and TR5 which were produced on the higher amount of hemicellulosic hydrolysate, possess both high xylanase and β-xylosidase activities, and were the most efficient for xylans hydrolysis. When hydrolysis of Avicel was conducted in presence of xylans, a decrease of glucose release occurred for all cocktails compared to hydrolysis of Avicel alone. Mixing TR1 and TR5 cocktails with two different ratios of proteins (1/1 and 1/4) resulted in a gain of efficiency for glucose release during hydrolysis of Avicel in presence of xylans compared to TR5 alone. Our results demonstrate the importance of combining hemicellulase and cellulase activities to improve the yields of glucose release from Avicel in presence of xylans. In this context, strategies involving enzymes production with carbon sources comprising mixed C5 and C6 sugars or combining different cocktails produced on C5 or on C6 sugars are of interest for processes developed in the context of lignocellulosic biorefinery. PMID:27001439

  4. DETECTION OF A COMPANION LENS GALAXY USING THE MID-INFRARED FLUX RATIOS OF THE GRAVITATIONALLY LENSED QUASAR H1413+117

    SciTech Connect

    MacLeod, Chelsea L.; Agol, Eric; Kochanek, Christopher S.

    2009-07-10

    We present the first resolved mid-infrared (IR) (11 {mu}m) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a 'flux anomaly', where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to reproduce the mid-IR flux ratios, which are insensitive to extinction and microlensing, by modeling the main lens as a singular isothermal ellipsoid. This model fails to reproduce the flux ratios. However, we can explain the flux ratios simply by adding to the model a nearby galaxy detected in the H band by the Hubble Space Telescope. This perturbing galaxy lies 4.''0 from the main lens and it has a critical radius of 0.''63 {+-} 0.''02 which is similar to that of the main lens, as expected from their similar H-band fluxes. More remarkably, this galaxy is not required to obtain a good fit to the system astrometry, so this represents the first clear detection of an object through its effect on the image fluxes of a gravitational lens. This is a parallel to the detections of visible satellites from astrometric anomalies, and provides a proof of the concept of searching for substructure in galaxies using anomalous flux ratios.

  5. Single-Step 3-D Image Reconstruction in Magnetic Induction Tomography: Theoretical Limits of Spatial Resolution and Contrast to Noise Ratio

    PubMed Central

    Hollaus, Karl; Rosell-Ferrer, Javier; Merwa, Robert

    2006-01-01

    Magnetic induction tomography (MIT) is a low-resolution imaging modality for reconstructing the changes of the complex conductivity in an object. MIT is based on determining the perturbation of an alternating magnetic field, which is coupled from several excitation coils to the object. The conductivity distribution is reconstructed from the corresponding voltage changes induced in several receiver coils. Potential medical applications comprise the continuous, non-invasive monitoring of tissue alterations which are reflected in the change of the conductivity, e.g. edema, ventilation disorders, wound healing and ischemic processes. MIT requires the solution of an ill-posed inverse eddy current problem. A linearized version of this problem was solved for 16 excitation coils and 32 receiver coils with a model of two spherical perturbations within a cylindrical phantom. The method was tested with simulated measurement data. Images were reconstructed with a regularized single-step Gauss–Newton approach. Theoretical limits for spatial resolution and contrast/noise ratio were calculated and compared with the empirical results from a Monte-Carlo study. The conductivity perturbations inside a homogeneous cylinder were localized for a SNR between 44 and 64 dB. The results prove the feasibility of difference imaging with MIT and give some quantitative data on the limitations of the method. PMID:17031597

  6. Application of contrast-to-noise ratio in optimizing beam quality for digital chest radiography: comparison of experimental measurements and theoretical simulations

    NASA Astrophysics Data System (ADS)

    Doyle, P.; Martin, C. J.; Gentle, D.

    2006-06-01

    The contrast-to-noise ratio (CNR) has been employed in optimizing beam quality for imaging a chest phantom using digital radiography. The relationship between CNR and tube potential has been studied for regions of different attenuations representing the lung, heart and abdomen, and a figure of merit (FOM) incorporating effective dose has been calculated to enable dose performance to be included. Direct measurements of imaging performance have been compared with simulations based on a model representing object attenuations. The study has shown reasonable agreement between measurements of CNR and calculated values. The CNR values in the lung and heart regions are higher at 60-80 kV, while those for the abdomen are higher at 90-110 kV. Incorporating a 0.2 mm copper filter has minimal effect on image quality and the FOM is higher because of the reduction in dose. For imaging the heart and abdomen, performance was improved through use of a technique to remove scatter, with an air-gap technique giving a higher FOM because of the lower dose. The CNR and FOM can provide useful quantities for evaluating imaging performance to optimize beam quality for different imaging tasks.

  7. Contrasting effects of age on the plasma/whole blood lead ratio in men and women with a history of lead exposure

    SciTech Connect

    Barbosa, Fernando; Curtius, Adilson J.; Buzalaf, Marilia R.; Tanus-Santos, Jose E.

    2006-09-15

    We examined the effect of age and sex on the relationship between the concentrations of Pb in blood (Pb-B) and in plasma (Pb-P) in an adult population with a history of lead exposure. Pb-P was determined by inductively coupled plasma mass spectrometry (ICP-MS) and Pb-B by graphite furnace atomic absorption spectrometry (GF AAS). We studied 154 adults (56 men and 98 women) from 18 to 60-year old. Pb-B levels varied from 10.0 to 428.0 {mu}g/L, with a mean of 76 {mu}g/L. Blood lead levels varied from 10.0 to 428.0 {mu}g/L in men (mean, 98.3 {mu}g/L) and from 10.0 to 263.0 {mu}g/L (mean, 62.8 {mu}g/L) in women. Corresponding Pb-Ps were 0.02-2.9 {mu}g/L (mean, 0.66 {mu}g/L) and 0.02-1.5 {mu}g/L (mean, 0.42 {mu}g/L) in men and women, respectively. The relationship between Pb-B and Pb-P was found to be curvilinear (r=0.757, P<0.001 Spearman's correlation). The two quantities are related by the line y=0.0006x {sup 1492} (y=Pb-P, and x=Pb-B). The %Pb-P/Pb-B ratio ranged from 0.03% to 1.85%. A positive association was found between %Pb-P/Pb-B ratio and Pb-B levels. When data were separated by sex, this association was also relevant for men (y=0.0184x {sup 0.702}) and women (y=0.0534x {sup 0.5209}) (y=%Pb-P/Pb-B and x=Pb-B). Moreover, we found an interesting positive correlation between Log (Pb-P/Pb-B) and age for women (r=0.31, P<0.0001) and a negative correlation for men (r=-0.164, P=0.07). Taken together, these results suggest contrasting effects of age on the plasma/whole blood lead ratio in men and women with a history of lead exposure. Moreover, sex might play an important role in the metabolism of lead, implying further consideration on the kinetic models constructed of lead toxicity.

  8. Measurement and analysis of perceivable signal-to-noise ratio for infrared imaging system with human vision

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Zhao, Jing; Chang, Honghua; Ma, Lin

    2012-12-01

    The relationship between correct discrimination probability of the human eye and perceivable signal-to-noise (SNR) threshold is studied for different equilateral triangle sizes with specified luminance through combining theoretical calculation with practical experiment based on triangle orientation discrimination (TOD) performance evaluation method. Specifically, the simulation images of triangle patterns are generated by an infrared imaging system (IRIS) simulation model. And the perceivable SNRs for these images are calculated by establishing the system theoretical model and the human vision system model. Meanwhile, the Four-Alternative Forced-Choice experiment is performed. Experiment results of several observers are averaged statistically and the curves of perceivable SNR threshold which change with the correct discrimination probability are obtained. Finally, the analyses of these results show that these changes are in accordance with the psychometric function and that the fitting curves become steep with the increase of triangle sizes. These data and conclusions are helpful to modify the existing TOD performance model of an IRIS.

  9. Maximizing Iodine Contrast-to-Noise Ratios in Abdominal CT Imaging through Use of Energy Domain Noise Reduction and Virtual Monoenergetic Dual-Energy CT1

    PubMed Central

    Leng, Shuai; Yu, Lifeng; Fletcher, Joel G.; McCollough, Cynthia H.

    2015-01-01

    Purpose To determine the iodine contrast-to-noise ratio (CNR) for abdominal computed tomography (CT) when using energy domain noise reduction and virtual monoenergetic dual-energy (DE) CT images and to compare the CNR to that attained with single-energy CT at 80, 100, 120, and 140 kV. Materials and Methods This HIPAA-compliant study was approved by the institutional review board with waiver of informed consent. A syringe filled with diluted iodine contrast material was placed into 30-, 35-, and 45-cm-wide water phantoms and scanned with a dual-source CT scanner in both DE and single-energy modes with matched scanner output. Virtual monoenergetic images were generated, with energies ranging from 40 to 110 keV in 10-keV steps. A previously developed energy domain noise reduction algorithm was applied to reduce image noise by exploiting information redundancies in the energy domain. Image noise and iodine CNR were calculated. To show the potential clinical benefit of this technique, it was retrospectively applied to a clinical DE CT study of the liver in a 59-year-old male patient by using conventional and iterative reconstruction techniques. Image noise and CNR were compared for virtual monoenergetic images with and without energy domain noise reduction at each virtual monoenergetic energy (in kiloelectron volts) and phantom size by using a paired t test. CNR of virtual monoenergetic images was also compared with that of single-energy images acquired with 80, 100, 120, and 140 kV. Results Noise reduction of up to 59% (28.7/65.7) was achieved for DE virtual monoenergetic images by using an energy domain noise reduction technique. For the commercial virtual monoenergetic images, the maximum iodine CNR was achieved at 70 keV and was 18.6, 16.6, and 10.8 for the 30-, 35-, and 45-cm phantoms. After energy domain noise reduction, maximum iodine CNR was achieved at 40 keV and increased to 30.6, 25.4, and 16.5. These CNRs represented improvement of up to 64% (12.0/18.6) with

  10. A far-infrared study of the N/O abundance ratio in galactic H II regions

    NASA Technical Reports Server (NTRS)

    Lester, D. F.; Dinerstein, H. L.; Werner, M. W.; Watson, D. M.; Genzel, R. L.

    1983-01-01

    New measurements are presented for W43 (G30.8-0.0), Orion A, and G75.84+0.4, which are located at widely varying distances from the galactic center. The combination of the forbidden N III 57.3 microns and forbidden O III 88.4 and 51.8 microns yields measurements of N(++)/O(++) that are for the most part insensitive to electron temperature and density uncertainties and to clumping of the ionized gas. This is due to the similarity of the critical densities for these transitions. It is contended that for the observed nebulae, N(++)/O(++) should be indicative of N/O, a ratio that is of signal importance in nucleosynthesis theory. The measurements are compared with previous measurements of M17 and W51, which lie at intermediate galactocentric distances. For nebulae in the solar circle, it is found that N(++)/O(++) is greater than the N/O values derived from optical studies of N(+)/O(+) in low-ionization zones of the same nebulae. Possible sources of this discrepancy are considered. It is found that N(++)/O(++) in W43 is significantly higher than for the other H II regions in the sample. Since W43 is located at R = 5 kpc, which is the smallest galactocentric distance in the sample, the data are seen as consistent with the presence of a negative abundance gradient d(N/O)/dR.

  11. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent

    SciTech Connect

    Moore, Evan G.; Seitz, Michael; Raymond, Kenneth N.

    2008-06-09

    It has been more than a decade since the first reports of [Gd(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] as a potential new class of magnetic resonance imaging contrast agent (MRI-CA). The defining feature of these 1-methyl-3-hydroxypyridin-2-one (Me-3,2-HOPO) based compounds has been the use of a hexadentate ligand design, and hence an increase in the number of metal bound water molecules, without sacrificing complex stability compared to the typically octadentate contrast agents used commercially. Since that time, significant advances in the properties of these chelates have been steadily reported, including improvements in relaxivity, incorporation into macromolecular architectures and, recently, the first direct verification of solution structure using the discovery of Eu(III) centered luminescence with the isomeric 1-hydroxypyridin-2-one (1,2-HOPO) chelate as a sensitizing chromophore. Nonetheless, it has remained frustrating that direct measurements of the inner sphere hydration state, q, using luminescence techniques with the parent Me-3,2-HOPO compounds have remained elusive, even when direct laser excitation of weakly absorbing f-f transitions were employed (eg. for Eu(III) complexes). This failing can likely be traced to the presence of a low lying LMCT state which efficiently quenches metal based emission. Instead, estimates of the q and hence solution structure have relied on the fitting of relaxivity data to the Solomon-Bloembergen-Morgan equations or, where sufficiently soluble in aqueous solution, studies on the temperature dependence of the paramagnetic contribution to the water {sup 17}O NMR transverse relaxation rate. Recently, Beeby et al reported on a qualitative equation to determine inner sphere hydration based on the change in lifetimes for Yb(III) in going from H{sub 2}O to D{sub 2}O solution, and we reasoned that the lower energy accepting state of Yb(III) may lie below the LMCT state which quenches Eu(III) emission, and hence may facilitate

  12. Solid Phase Extraction Using C-18 Sorbents to Treat Organics in Water and Eliminate Spectral Interference in Isotope Ratio Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chang, E.; Caylor, K. K.; Gerlein-Safdi, C.; Wolf, A.

    2015-12-01

    Although isotope ratio infrared spectroscopy (IRIS) provides an inexpensive, convenient instrumentation for water isotope analysis, analyzing δ2H and δ18O becomes much less accurate if the water contains organic contaminants. Alcohols such as Ethanol and Methanol cause significant changes in the apparent isotope values such that the more these species are present in the water, the more erroneous the IRIS data becomes. Although activated charcoal and pre-combustion methods have typically been used to mitigate this inaccuracy, a new application of Solid Phase Extraction (SPE) using C-18 sorbents shows promising results in eliminating more organics and reducing spectral interferences more than current treatment techniques. SPE's can be prepared in the field and can quickly treat samples upon collection: this study focuses on developing a consistent method for use both in field and lab to allow isotope hydrology measurements to be unhampered by potential organics. To study the adsorption effect of SPE's, we used H-NMR technology to calculate absolute concentrations of Ethanol and Methanol in water pre- and post- treatment. SPE removed up to 90% Ethanol and 60% Methanol in water, and the corresponding measured isotopic values after alcohol removal were much closer to the pure water reference.

  13. Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Halo Occupation Number, Mass-to-Light Ratios and Omega(M)

    SciTech Connect

    Muzzin, Adam; Yee, H.K.C.; Hall, Patrick B.; Lin, Huan; /Fermilab

    2007-03-01

    Using K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters we examine the near-infrared properties of moderate-redshift (0.19 < z < 0.55) galaxy clusters. We find that the number of K-band selected cluster galaxies within R{sub 500} (the Halo Occupation Number, HON) is well-correlated with the cluster dynamical mass (M{sub 500}) and X-ray Temperature (T{sub x}); however, the intrinsic scatter in these scaling relations is 37% and 46% respectively. Comparison with clusters in the local universe shows that the HON-M{sub 500} relation does not evolve significantly between z = 0 and z {approx} 0.3. This suggests that if dark matter halos are disrupted or undergo significant tidal-stripping in high-density regions as seen in numerical simulations, the stellar mass within the halos is tightly bound, and not removed during the process. The total K-band cluster light (L{sub 200},K) and K-band selected richness (parameterized by B{sub gc,K}) are also correlated with both the cluster T{sub x} and M{sub 200}. The total (intrinsic) scatter in the L{sub 200,K}-M{sub 200} and B{sub gc,K}-M{sub 200} relations are 43%(31%) and 35%(18%) respectively and indicates that for massive clusters both L{sub 200,K} and B{sub gc,K} can predict M{sub 200} with similar accuracy as T{sub x}, L{sub x} or optical richness (B{sub gc}). Examination of the mass-to-light ratios of the clusters shows that similar to local clusters, the K-band mass-to-light ratio is an increasing function of halo mass. Using the K-band mass-to-light ratios of the clusters, we apply the Oort technique and find {Omega}{sub m,0} = 0.22 {+-} 0.02, which agrees well with recent combined concordance cosmology parameters, but, similar to previous cluster studies, is on the low-density end of preferred values.

  14. A single diamagnetic catalyCEST MRI contrast agent that detects cathepsin B enzyme activity by using a ratio of two CEST signals

    PubMed Central

    Hingorani, Dina V.; Montano, Luis A.; Randtke, Edward A.; Lee, Yeon Sun; Cárdenas-Rodríguez, Julio; Pagel, Mark D.

    2016-01-01

    CatalyCEST MRI can detect enzyme activity by monitoring the change in chemical exchange with water after a contrast agent is cleaved by an enzyme. Often these molecules use paramagnetic metals and are delivered with an additional non-responsive reference molecule. To improve this approach for molecular imaging, a single diamagnetic agent with enzyme-responsive and enzyme-unresponsive CEST signals was synthesized and characterized. The CEST signal from the aryl amide disappeared after cleavage of a dipeptidyl ligand with cathepsin B, while a salicylic acid moiety was largely unresponsive to enzyme activity. The ratiometric comparison of the two CEST signals from the same agent allowed for concentration independent measurements of enzyme activity. The chemical exchange rate of the salicylic acid moiety was unchanged after enzyme catalysis, which further validated that this moiety was enzyme-unresponsive. The temperature dependence of the chemical exchange rate of the salicylic acid moiety was non-Arrhenius, suggesting a two-step chemical exchange mechanism for salicylic acid. The good detection sensitivity at low saturation power facilitates clinical translation, along with the potentially low toxicity of a non-metallic MRI contrast agent. The modular design of the agent constitutes a platform technology that expands the variety of agents that may be employed by catalyCEST MRI for molecular imaging. PMID:26633584

  15. Contrasting winter and summer VOC mixing ratios at a forest site in the Western Mediterranean Basin: the effect of local biogenic emissions

    NASA Astrophysics Data System (ADS)

    Seco, R.; Peñuelas, J.; Filella, I.; Llusià, J.; Molowny-Horas, R.; Schallhart, S.; Metzger, A.; Müller, M.; Hansel, A.

    2011-12-01

    Atmospheric volatile organic compounds (VOCs) are involved in ozone and aerosol generation, thus having implications for air quality and climate. VOCs and their emissions by vegetation also have important ecological roles as they can protect plants from stresses and act as communication cues between plants and between plants and animals. In spite of these key environmental and biological roles, the reports on seasonal and daily VOC mixing ratios in the literature for Mediterranean natural environments are scarce. We conducted seasonal (winter and summer) measurements of VOC mixing ratios in an elevated (720 m a.s.l.) holm oak Mediterranean forest site near the metropolitan area of Barcelona (NE Iberian Peninsula). Methanol was the most abundant compound among all the VOCs measured in both seasons. While aromatic VOCs showed almost no seasonal variability, short-chain oxygenated VOCs presented higher mixing ratios in summer, presumably due to greater emission by vegetation and increased photochemistry, both enhanced by the high temperatures and solar radiation in summer. Isoprenoid VOCs showed the biggest seasonal change in mixing ratios: they increased by one order of magnitude in summer, as a result of the vegetation's greater physiological activity and emission rates. The maximum diurnal concentrations of ozone increased in summer too, most likely due to more intense photochemical activity and the higher levels of VOCs in the air. The daily variation of VOC mixing ratios was mainly governed by the wind regime of the mountain, as the majority of the VOC species analyzed followed a very similar diel cycle. Mountain and sea breezes that develop after sunrise advect polluted air masses to the mountain. These polluted air masses had previously passed over the urban and industrial areas surrounding the Barcelona metropolitan area, where they were enriched in NOx and in VOCs of biotic and abiotic origin. Moreover, these polluted air masses receive additional biogenic

  16. Contrasting winter and summer VOC mixing ratios at a forest site in the Western Mediterranean Basin: the effect of local biogenic emissions

    NASA Astrophysics Data System (ADS)

    Seco, R.; Peñuelas, J.; Filella, I.; Llusià, J.; Molowny-Horas, R.; Schallhart, S.; Metzger, A.; Müller, M.; Hansel, A.

    2011-07-01

    Atmospheric volatile organic compounds (VOCs) are involved in ozone and aerosol generation, thus having implications for air quality and climate. VOCs and their emissions by vegetation also have important ecological roles as they can protect plants from stresses and act as communication cues between plants and between plants and animals. In spite of these key environmental and biological roles, the reports on seasonal and daily VOC mixing ratios in the literature for Mediterranean natural environments are scarce. We conducted seasonal (winter and summer) measurements of VOC mixing ratios in an elevated (720 m a.s.l.) holm oak Mediterranean forest site near the metropolitan area of Barcelona (NE Iberian peninsula). Methanol was the most abundant compound among all the VOCs measured in both seasons. While aromatic VOCs showed almost no seasonal variability, short-chain oxygenated VOCs presented higher mixing ratios in summer, presumably due to greater emission by vegetation and increased photochemistry, both enhanced by the high temperatures and solar radiation in summer. Isoprenoid VOCs showed the biggest seasonal change in mixing ratios: they increased by one order of magnitude in summer, as a result of the vegetation's greater physiological activity and emission rates. The maximum diurnal concentrations of ozone increased in summer too, most likely due to more intense photochemical activity and the higher levels of VOCs in the air. The daily variation of VOC mixing ratios was mainly governed by the wind regime of the mountain, as the majority of the VOC species analyzed followed a very similar diel cycle. Mountain and sea breezes that develop after sunrise advect polluted air masses to the mountain. These polluted air masses had previously passed over the urban and industrial areas surrounding the Barcelona metropolitan area, where they were enriched in NOx and in VOCs of biotic and abiotic origin. Moreover, these polluted air masses receive additional biogenic

  17. 13C-methacetin breath test: isotope-selective nondispersive infrared spectrometry in comparison to isotope ratio mass spectrometry in volunteers and patients with liver cirrhosis.

    PubMed

    Adamek, R J; Goetze, O; Boedeker, C; Pfaffenbach, B; Luypaerts, A; Geypens, B

    1999-12-01

    The 13C-methacetin breath test (MBT) has been proposed for the noninvasive evaluation of the hepatic mixed function oxidase activity. Up to now, stable isotope analysis of carbon dioxide of the MBT has been carried out with isotope ratio mass spectrometry (IRMS). The aim of the present study was to test a recently developed isotope-selective nondispersive infrared spectrometer (NDIRS) in comparison to IRMS in healthy volunteers and patients with liver cirrhosis. Ten healthy volunteers (range 22 to 76 years) and ten patients with histologically proven liver cirrhosis (range 47 to 71 years; Child Pugh score A = 5, B = 3, C = 2) were studied. After an overnight fast each subject received 2 mg/kg BW of 13C-methacetin dissolved in 100 ml of tea. Breath samples were obtained before substrate administration and after 5, 10, 15, 20, 30, 40, 50, 60, 80, 100, 120, 150, 180 min. The 13C/12C-ratio was analyzed in each breath sample both by NDIRS (IRIS, Wagner Analysen Technik, Worpswede, Germany) and CF-IRMS (ABCA, Europa Scientific, Crewe, UK). Results were expressed as delta over baseline (DOB [/1000]) and as cumulative percentage doses of 13C recovered (cPDR [%]) at each time interval. Correlations between IRMS and NDIRS were tested by linear regression correlation. For measuring agreement an Altman-Bland-plot was performed. Applying correlation analysis a linear correlation was found (DOB: y = 1.068 +/- 0.0012.x + 2.088 +/- 0.2126, r = 0.98, p < 0.0001; cPDR: y = 1.148 +/- 0.0109.x + 0.569 +/- 0.172; r = 0.99, p < 0.0001). For DOB the mean difference (d) was 2.9/1000 and the standard deviation (SD) of the difference was 2.7/1000. The limits of agreement (d +/- SD) were -2.5/1000 and 8.3/1000. The comparison of DOB- and cPDR-values by NDIRS and IRMS shows a high linear correlation. However, the distance of the limits of agreement is wide. Consequently, the validity of the MBT could be influenced which could make MBT by NDIRS unprecise for exact evaluation of hepatocellular

  18. The contrast study of anammox-denitrifying system in two non-woven fixed-bed bioreactors (NFBR) treating different low C/N ratio sewage.

    PubMed

    Gao, Fan; Zhang, Hanmin; Yang, Fenglin; Qiang, Hong; Zhang, Guangyi

    2012-06-01

    Two non-woven fixed-bed bioreactors (NFBR) based on different substrates (nitrite and nitrate) were constructed to study the environmental adaptability for temperature and organic matter of anammox-denitrifying system and nitrogen removal performance. The two reactors were successfully operated for 200 days. The average removal rates of nitrogen and COD of R2 were 81% and 93%, respectively. Besides, the nitrogen removal rate of R1 was 95% under not more than 105 mg/l of COD. The experimental results indicated that the R2 based on nitrate had a good nitrogen removal performance at room temperature (25 °C). Additionally, the analysis results of fluorescence in situ hybridization (FISH) showed that the percentage compositions of anammox in R1 and R2 were 84% and 65% on day 189. Finally, the possible nitrogen removal model of anammox-denitrifying system was constructed. According to nitrogen balance and C/N ratios of denitrification, the nitrogen removal approaches of R1 and R2 were obtained. PMID:22446054

  19. Comparison of S/N Ratios for Magnesium diboride (MgB2) Superconducting detectors vs Bi-Te thermopiles when used in an infrared radiometer.

    NASA Astrophysics Data System (ADS)

    lakew, b.; Aslam, S.

    2014-04-01

    Mapping the surface temperature of cold Jovian moons like Europa or Ganymede requires an accurate measurement of their infrared spectral radiance. One measurement technique employs a radiometer with thermopile linear arrays. Each array is in turn integrated with infrared filters of the appropriate wavelength pass bands. The performance of such a radiometer when using an array of thermopile detectors vs an array of superconducting magnesium-diboride (MgB2) detectors.

  20. Comparison of Fourier Transform Infrared Spectroscopy (FTIR) and Tunable Diode Laser Absorption Spectroscopy (TDLAS) Methods for Determining Stable Isotope Ratios of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Ubierna Lopez, N.; Cambaliza, M. L.; Griffith, D. W.; Mount, G. H.; Cousins, A. B.

    2011-12-01

    Worldwide, biosphere-atmosphere carbon exchange and net ecosystem exchange (NEE) are determined using eddy-covariance methods. Information from isotopic CO2 measurements provides valuable constraints to partition NEE into its component fluxes. Stable isotope measurements have traditionally been constrained in frequency by the need to collect and analyze field samples in a laboratory using isotope ratio mass spectrometry (MS). New techniques based on absorption spectroscopy allow for high temporal sampling resolution in the field, but with concerns about precision and accuracy of the isotope-ratios. We tested two absorption spectroscopy systems, a Fourier transformed infrared analyzer (FTIR, Vector 22, Bruker Optics, Ettlingen, Germany) and a tunable diode laser absorption spectrometer (TDLAS, model TGA 100, Campbell Scientific, Inc. Logan, UT, USA), by comparing them with continuous-flow MS (Delta plus XP IRMS, ThermoFinnigan, Bremen, Germany). We conducted a laboratory comparison of gases mixed with various CO2 concentrations and isotopic signatures as well as field-collected samples. The mixed tanks were balanced in ultra-zero air with CO2 concentrations ranging from 353 to 553 ppm, and isotopic compositions (δ13C) between -11.7% to -39.3%. The field samples were collected at four different locations (forest, wheat field, dairy farm, and paper mill) by pumping ambient air into 44- L tanks. Gas from each sample tank was simultaneously delivered to the FTIR and TDLAS systems and subsequently analyzed with continuous-flow MS. The [CO2] determined with the TDLAS or FTIR differed by <1 ppm for CO2-tanks and <2.4 ppm for ambient air samples. The δ13C offset of the CO2 tanks between the MS and the TDLAS and FTIR were on average 0.1% and 0.3%, respectively. However, the offset in TDLAS δ13C values increased for ambient air samples to values of 0.4%, with a maximum of 0.9% for the dairy farm and paper mill samples. Ambient air samples analyzed with the FTIR were on

  1. Contrast studies.

    PubMed

    Anderson, Susan M

    2006-01-01

    Contrast media plays an important role in imaging soft tissues and organs. Though contrast imaging is considered safe, radiologic technologists can improve the safety of contrast examinations by reviewing institutional safety procedures, safe practices for different methods of contrast administration and possible complications. The need for efficient communication and attention to detail during contrast procedures is essential for patient safety. PMID:16998193

  2. Near-infrared fluorescence imaging of experimentally collagen-induced arthritis in rats using the nonspecific dye tetrasulfocyanine in comparison with gadolinium-based contrast-enhanced magnetic resonance imaging, histology, and clinical score

    NASA Astrophysics Data System (ADS)

    Gemeinhardt, Ines; Puls, Dorothee; Gemeinhardt, Ole; Taupitz, Matthias; Wagner, Susanne; Schnorr, Beatrix; Licha, Kai; Schirner, Michael; Ebert, Bernd; Petzelt, Diethard; Macdonald, Rainer; Schnorr, Jörg

    2012-10-01

    Using 15 rats with collagen-induced arthritis (30 joints) and 7 control rats (14 joints), we correlated the intensity of near-infrared fluorescence (NIRF) of the nonspecific dye tetrasulfocyanine (TSC) with magnetic resonance imaging (MRI), histopathology, and clinical score. Fluorescence images were obtained in reflection geometry using a NIRF camera system. Normalized fluorescence intensity (INF) was determined after intravenous dye administration on different time points up to 120 min. Contrast-enhanced MRI using gadodiamide was performed after NIRF imaging. Analyses were performed in a blinded fashion. Histopathological and clinical scores were determined for each ankle joint. INF of moderate and high-grade arthritic joints were significantly higher (p<0.005) than the values of control and low-grade arthritic joints between 5 and 30 min after TSC-injection. This result correlated well with post-contrast MRI signal intensities at about 5 min after gadodiamide administration. Furthermore, INF and signal increase on contrast-enhanced MRI showed high correlation with clinical and histopathological scores. Sensitivities and specificities for detection of moderate and high-grade arthritic joints were slightly lower for NIRF imaging (89%/81%) than for MRI (100%/91%). NIRF imaging using TSC, which is characterized by slower plasma clearance compared to indocyanine green (ICG), has the potential to improve monitoring of inflamed joints.

  3. Hybrid Lyot coronagraph for wide-field infrared survey telescope-astrophysics focused telescope assets: occulter fabrication and high contrast narrowband testbed demonstration

    NASA Astrophysics Data System (ADS)

    Seo, Byoung-Joon; Gordon, Brian; Kern, Brian; Kuhnert, Andy; Moody, Dwight; Muller, Richard; Poberezhskiy, Ilya; Trauger, John; Wilson, Daniel

    2016-01-01

    Hybrid Lyot coronagraph (HLC) is one of the two operating modes of the WFIRST-AFTA coronagraph instrument. It produces starlight suppression over the full 360-deg annular region and thus is particularly suitable to improve the discovery space around WFIRST-AFTA targets. Since being selected by the National Aeronautics and Space Administration in December 2013, the coronagraph technology is being matured to technology readiness level 5 by September 2016. We present the progress of HLC key component fabrication and testbed demonstrations with the WFIRST-AFTA pupil. For the first time, a circular HLC occulter mask consisting of metal and dielectric layers is fabricated and characterized. Wavefront control using two deformable mirrors is successfully demonstrated in a vacuum testbed with narrowband light (<1-nm bandwidth at 516 nm) to obtain repeatable convergence below 8×10-9 mean contrast in the 360-deg dark hole with a working angle between 3λ/D and 9λ/D with arbitrary polarization. We detail the hardware and software used in the testbed, the results, and the associated analysis.

  4. An improved infrared technique for sorting pecans

    NASA Astrophysics Data System (ADS)

    Graeve, Thorsten; Dereniak, Eustace L.; Lamonica, John A., Jr.

    1991-10-01

    This paper presents the results of a study of pecan spectral reflectances. It describes an experiment for measuring the contrast between several components of raw pecan product to be sorted. An analysis of the experimental data reveals high contrast ratios in the infrared spectrum, suggesting a potential improvement in sorting efficiency when separating pecan meat from shells. It is believed that this technique has the potential to dramatically improve the efficiency of current sorting machinery, and to reduce the cost of processing pecans for the consumer market.

  5. Ultraviolet and near-infrared femtosecond temporal pulse shaping with a new high-aspect-ratio one-dimensional micromirror array.

    PubMed

    Weber, Stefan M; Extermann, Jérôme; Bonacina, Luigi; Noell, Wilfried; Kiselev, Denis; Waldis, Severin; de Rooij, Nico F; Wolf, Jean-Pierre

    2010-09-15

    We demonstrate the capabilities of a new optical microelectromechanical systems device that we specifically developed for broadband femtosecond pulse shaping. It consists of a one-dimensional array of 100 independently addressable, high-aspect-ratio micromirrors with up to 3 μm stroke. We apply linear and quadratic phase modulations demonstrating the temporal compression of 800 and 400 nm pulses. Because of the device's surface flatness, stroke, and stroke resolution, phase shaping over an unprecedented bandwidth is attainable. PMID:20847792

  6. Target detection in desert backgrounds: infrared hyperspectral measurements and analysis

    NASA Astrophysics Data System (ADS)

    Eismann, Michael T.; Seldin, John H.; Schwartz, Craig R.; Maxwell, James R.; Ellis, Kenneth K.; Cederquist, Jack N.; Stocker, Alan D.; Oshagan, Ara; Johnson, Ray O.; Shaffer, William A.; Surette, Marc R.; McHugh, Martin J.; Schaum, Alan P.; Stotts, Larry B.

    1995-09-01

    Infrared multispectral sensors are being investigated as a means for day and night target detection. Infrared multispectral sensors would exploit high spectral band-to-band correlation to reject high background clutter. An infrared Fourier transform spectrometer-based field measurement system was used to collect spectral signature data of targets and desert scrub and sand backgrounds from a 100 foot tower at White Sands Missile Range. The measurements include target-to-background spectral contrast, subpixel targets, background spectral correlation, and background spatial power spectra. The measurements have been analyzed to determine multispectral signal-to-clutter ratios versus target, background, diurnal, and weather variations, background correlation versus temperature clutter variations, and spectral correlation versus spatial scale. These measurements contribute to the expanding target and background infrared hyperspectral signature database. The results of the analysis demonstrate the utility and robustness of infrared multispectral techniques for target detection.

  7. Contrastive Lexicology.

    ERIC Educational Resources Information Center

    Hartmann, R. R. K.

    This paper deals with the relation between etymologically related words in different languages. A survey is made of seven stages in the development of contrastive lexicology. These are: prelinguistic word studies, semantics, lexicography, translation, foreign language learning, bilingualism, and finally contrastive analysis. Concerning contrastive…

  8. Contrast Materials

    MedlinePlus

    ... or other reactions to contrast materials are rare, radiology departments are well-equipped to deal with them. ... is given. However, both the American College of Radiology (ACR) and the European Society of Urogenital Radiology ...

  9. The investigations of changes in mineral-organic and carbon-phosphate ratios in the mixed saliva by synchrotron infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Seredin, Pavel; Goloshchapov, Dmitry; Kashkarov, Vladimir; Ippolitov, Yuri; Bambery, Keith

    The objective of this study was to investigate the efficiency of the saturation of mixed saliva by mineral complexes and groups necessary for the remineralisation of tooth enamel using exogenous and endogenous methods of caries prevention. Using IR spectroscopy and high-intensity synchrotron radiation, changes in the composition of the human mixed saliva were identified when exogenous and endogenous methods of caries prevention are employed. Based on the calculations of mineral/organic and carbon/phosphate ratios, changes in the composition of the human mixed saliva depending on a certain type of prevention were identified. It is shown that the use of a toothpaste (exogenous prevention) alone based on a multi-mineral complex including calcium glycerophosphate provides only a short-term effect of saturating the oral cavity with mineral complexes and groups. Rinsing of the oral cavity with water following the preventive use of a toothpaste completely removes the effect of the saturation of the mixed saliva with mineral groups and complexes. The use of tablets of a multi-mineral complex with calcium glycerophosphate (endogenous prevention) in combination with exogenous prevention causes an average increase of ∼10% in the content of mineral groups and complexes in the mixed saliva and allows long-term saturation of the oral fluid by them. This method outperforms the exogenous one owing to a long-term effect of optimal concentrations of endogenous and biologically available derivatives of phosphates on the enamel surface.

  10. Time delay and excitation mode induced tunable red/near-infrared to green emission ratio of Er doped BiOCl

    NASA Astrophysics Data System (ADS)

    Avram, Daniel; Florea, Mihaela; Tiseanu, Ion; Tiseanu, Carmen

    2015-09-01

    Herein, we report on the emission color tunability of Er doped BiOCl measured under up—conversion as well as x-ray excitation modes. The dependence of red (670 nm) to green emission (543 nm) ratio on Er concentration (1 and 5%), excitation wavelength into different (656.4, 802 and 976 nm) or across single Er absorption levels (965 ÷ 990 nm) and delay after the laser pulse (0.001 ÷ 1 ms) is discussed in terms of ground state absorption/excited state absorption and energy transfer up-conversion mechanisms. A first example of extended Er x-ray emission measured in the range of 500 to 1700 nm shows comparable emission intensities corresponding to 543 nm and 1500 nm based transitions. The present results together with our earlier report on the upconversion emission of Er doped BiOCl excited at 1500 nm, suggest that Er doped BiOCl may be considered an attractive system for optical and x-ray imaging applications.

  11. Contrast lipocryolysis

    PubMed Central

    Pinto, Hernán; Melamed, Graciela

    2014-01-01

    Alternative crystal structures are possible for all lipids and each different crystal structure is called a polymorphic form. Inter-conversion between polymorphisms would imply the possibility of leaning crystal formation toward the most effective polymorphism for adipocyte destruction. Food industry has been tempering lipids for decades. Tempering technology applied to lipocryolysis gave birth to “contrast lipocryolysis”, which involves pre- and post-lipocryolysis fat layer heating as part of a specific tempering protocol. In this study, we evaluated the skinfold thickness of 10 subjects after a single contrast lipocryolysis session and witnessed important and fast reductions. PMID:25068088

  12. Analysis of Infrared Signature Variation and Robust Filter-Based Supersonic Target Detection

    PubMed Central

    Sun, Sun-Gu; Kim, Kyung-Tae

    2014-01-01

    The difficulty of small infrared target detection originates from the variations of infrared signatures. This paper presents the fundamental physics of infrared target variations and reports the results of variation analysis of infrared images acquired using a long wave infrared camera over a 24-hour period for different types of backgrounds. The detection parameters, such as signal-to-clutter ratio were compared according to the recording time, temperature and humidity. Through variation analysis, robust target detection methodologies are derived by controlling thresholds and designing a temporal contrast filter to achieve high detection rate and low false alarm rate. Experimental results validate the robustness of the proposed scheme by applying it to the synthetic and real infrared sequences. PMID:24672290

  13. Infrared retina

    DOEpatents

    Krishna, Sanjay; Hayat, Majeed M.; Tyo, J. Scott; Jang, Woo-Yong

    2011-12-06

    Exemplary embodiments provide an infrared (IR) retinal system and method for making and using the IR retinal system. The IR retinal system can include adaptive sensor elements, whose properties including, e.g., spectral response, signal-to-noise ratio, polarization, or amplitude can be tailored at pixel level by changing the applied bias voltage across the detector. "Color" imagery can be obtained from the IR retinal system by using a single focal plane array. The IR sensor elements can be spectrally, spatially and temporally adaptive using quantum-confined transitions in nanoscale quantum dots. The IR sensor elements can be used as building blocks of an infrared retina, similar to cones of human retina, and can be designed to work in the long-wave infrared portion of the electromagnetic spectrum ranging from about 8 .mu.m to about 12 .mu.m as well as the mid-wave portion ranging from about 3 .mu.m to about 5 .mu.m.

  14. Silicates in Ultraluminous Infrared Galaxies

    NASA Astrophysics Data System (ADS)

    Sirocky, M. M.; Levenson, N. A.; Elitzur, M.; Spoon, H. W. W.; Armus, L.

    2008-05-01

    We analyze the mid-infrared (MIR) spectra of ultraluminous infrared galaxies (ULIRGs) observed with the Spitzer Space Telescope's Infrared Spectrograph. Dust emission dominates the MIR spectra of ULIRGs, and the reprocessed radiation that emerges is independent of the underlying heating spectrum. Instead, the resulting emission depends sensitively on the geometric distribution of the dust, which we diagnose with comparisons of numerical simulations of radiative transfer. Quantifying the silicate emission and absorption features that appear near 10 and 18 μm requires a reliable determination of the continuum, and we demonstrate that including a measurement of the continuum at intermediate wavelength (between the features) produces accurate results at all optical depths. With high-quality spectra, we successfully use the silicate features to constrain the dust chemistry. The observations of the ULIRGs and local sight lines require dust that has a relatively high 18 μm/10 μm absorption ratio of the silicate features (around 0.5). Specifically, the cold dust of Ossenkopf et al. is consistent with the observations, while other dust models are not. We use the silicate feature strengths to identify two families of ULIRGs, in which the dust distributions are fundamentally different. Optical spectral classifications are related to these families. In ULIRGs that harbor an active galactic nucleus, the spectrally broad lines are detected only when the nuclear surroundings are clumpy. In contrast, the sources of lower ionization optical spectra are deeply embedded in smooth distributions of optically thick dust.

  15. Optically measured microvascular blood flow contrast of malignant breast tumors.

    PubMed

    Choe, Regine; Putt, Mary E; Carlile, Peter M; Durduran, Turgut; Giammarco, Joseph M; Busch, David R; Jung, Ki Won; Czerniecki, Brian J; Tchou, Julia; Feldman, Michael D; Mies, Carolyn; Rosen, Mark A; Schnall, Mitchell D; DeMichele, Angela; Yodh, Arjun G

    2014-01-01

    Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS), a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval) tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63); tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66), and using normal tissue in the contralateral breast was 2.27 (1.90-2.70). Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography. PMID:24967878

  16. Infrared Investigations.

    ERIC Educational Resources Information Center

    Lascours, Jean; Albe, Virginie

    2001-01-01

    Describes a series of simple and nontraditional experiments that enable students to discover the properties of infrared radiation by studying the propagation, reflection, diffusion, and refraction of infrared. The experiments rely on two modules, an infrared transmitter and an infrared receiver. (SAH)

  17. Psychophysical contrast calibration

    PubMed Central

    To, Long; Woods, Russell L; Goldstein, Robert B; Peli, Eli

    2013-01-01

    Electronic displays and computer systems offer numerous advantages for clinical vision testing. Laboratory and clinical measurements of various functions and in particular of (letter) contrast sensitivity require accurately calibrated display contrast. In the laboratory this is achieved using expensive light meters. We developed and evaluated a novel method that uses only psychophysical responses of a person with normal vision to calibrate the luminance contrast of displays for experimental and clinical applications. Our method combines psychophysical techniques (1) for detection (and thus elimination or reduction) of display saturating nonlinearities; (2) for luminance (gamma function) estimation and linearization without use of a photometer; and (3) to measure without a photometer the luminance ratios of the display’s three color channels that are used in a bit-stealing procedure to expand the luminance resolution of the display. Using a photometer we verified that the calibration achieved with this procedure is accurate for both LCD and CRT displays enabling testing of letter contrast sensitivity to 0.5%. Our visual calibration procedure enables clinical, internet and home implementation and calibration verification of electronic contrast testing. PMID:23643843

  18. 10-7 contrast ratio at 4.5λ/D: New results obtained in laboratory experiments using nano-fabricated coronagraph and multi-Gaussian shaped pupil masks

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhijit; Thompson, Laird A.; Rogosky, Michael

    2005-04-01

    We present here new experimental results on high contrast imaging of 10-7 at 4.λ/D (λ=0.820 microns) by combining a circular focal plane mask (coronagraph) of 2.5λ/D diameter and a multi-Gaussian pupil plane mask. Both the masks were fabricated on very high surface quality (λ/30) BK7 optical substrates using nano-fabrication techniques of photolithography and metal lift-off. This process ensured that the shaped masks have a useable edge roughness better than λ/4 (rms error better than 0.2 microns), a specification that is necessary to realize the predicted theoretical limits of any mask design. Though a theoretical model predicts a contrast level of 10-12, the background noise of the observed images was speckle dominated which reduced the contrast level to 4x10-7 at 4.5λ/D. The optical setup was built on the University of Illinois Seeing Improvement System (UnISIS) optics table which is at the Coude focus of the 2.5-m telescope of the Mt. Wilson Observatory. We used a 0.820 micron laser source coupled with a 5 micron single-mode fiber to simulate an artificial star on the optical test bench of UnISIS.

  19. 10(-7) contrast ratio at 4.5lambda/D: New results obtained in laboratory experiments using nano-fabricated coronagraph and multi-Gaussian shaped pupil masks.

    PubMed

    Chakraborty, Abhijit; Thompson, Laird; Rogosky, Michael

    2005-04-01

    We present here new experimental results on high contrast imaging of 10-7 at 4.lambda/D (lambda=0.820 microns) by combining a circular focal plane mask (coronagraph) of 2.5lambda/D diameter and a multi-Gaussian pupil plane mask. Both the masks were fabricated on very high surface quality (lambda/30) BK7 optical substrates using nano-fabrication techniques of photolithography and metal lift-off. This process ensured that the shaped masks have a useable edge roughness better than lambda/4 (rms error better than 0.2 microns), a specification that is necessary to realize the predicted theoretical limits of any mask design. Though a theoretical model predicts a contrast level of 10-12, the background noise of the observed images was speckle dominated which reduced the contrast level to 4x10-7 at 4.5lambda/D. The optical setup was built on the University of Illinois Seeing Improvement System (UnISIS) optics table which is at the Coude focus of the 2.5-m telescope of the Mt. Wilson Observatory. We used a 0.820 micron laser source coupled with a 5 micron single-mode fiber to simulate an artificial star on the optical test bench of UnISIS. PMID:19495130

  20. Deep infrared galaxies

    NASA Technical Reports Server (NTRS)

    Ashby, Matthew; Houck, J. R.; Hacking, Perry B.

    1992-01-01

    High signal-to-noise ratio optical spectra of 17 infrared-bright emission-line galaxies near the north ecliptic pole are presented. Reddening-corrected line ratios forbidden O III 5007/H-beta, N II 6583/H-alpha, S II (6716 + 6731)/H-alpha, and O I 6300/H-alpha are used to discriminate between candidate energy generation mechanisms in each galaxy. These criteria have frequently been applied to optically selected samples of galaxies in the past, but this is the first time they have been applied to a set of faint flux-limited infrared-selected objects. The analysis indicates the sample contains seven starburst galaxies and three (AGN). However, seven galaxies in the present sample elude the classification scheme based on these line ratios. It is concluded that a two-component (starburst plus AGN) model for energy generation is inadequate for infrared galaxies.

  1. Clouds of high contrast on Uranus.

    PubMed

    Karkoschka, E

    1998-04-24

    Near-infrared images of Uranus taken with the Hubble Space Telescope in July and October 1997 revealed discrete clouds with contrasts exceeding 10 times the highest contrast observed before with other techniques. At visible wavelengths, these 10 clouds had lower contrasts than clouds seen by Voyager 2 in 1986. Uranus' rotational rates for southern latitudes were identical in 1986 and 1997. Clouds in northern latitudes rotate slightly more slowly than clouds in opposite southern latitudes. PMID:9554844

  2. Infrared thermography

    SciTech Connect

    Roberts, C.C. Jr.

    1982-12-01

    Infrared thermography is a useful tool for the diagnosis of problems in building systems. In instances where a building owner has several large buildings, an investment in a typical $30,000 infrared system may be cost effective. In most instances, however, the rental of an infrared system or the hiring of an infrared consulting service is a cost effective alternative. As can be seen from the several applications presented here, any mechanical problem manifesting itself in an atypical temperature pattern can usually be detected. The two primary savings generated from infrared analysis of building systems are maintenance and energy.

  3. Enhancing the contrast of subcutaneous veins

    NASA Astrophysics Data System (ADS)

    Zeman, Herbert D.; Lovhoiden, Gunnar

    1999-07-01

    A technique for enhancing the contrast of subcutaneous veins has been demonstrated. This technique uses a near infrared light source and one or more infrared sensitive CCD TV cameras to produce a contrast enhanced image of the subcutaneous veins. This video image of the veins is projected back onto the patient's skin using an LCD vein projector. The use of an infrared transmitting filter in front of the video cameras prevents any positive feedback from the visible light from the video projector from causing instabilities in the projected image. The demonstration contrast enhancing illuminator has been tested on adults, both Caucasian and African-American, and it enhances veins quite well in most cases. Preliminary studies on a 9 month old girl indicate promise for pediatric use.

  4. A study of infrared spectroscopy de-noising based on LMS adaptive filter

    NASA Astrophysics Data System (ADS)

    Mo, Jia-qing; Lv, Xiao-yi; Yu, Xiao

    2015-12-01

    Infrared spectroscopy has been widely used, but which often contains a lot of noise, so the spectral characteristic of the sample is seriously affected. Therefore the de-noising is very important in the spectrum analysis and processing. In the study of infrared spectroscopy, the least mean square (LMS) adaptive filter was applied in the field firstly. LMS adaptive filter algorithm can reserve the detail and envelope of the effective signal when the method was applied to infrared spectroscopy of breast cancer which signal-to-noise ratio (SNR) is lower than 10 dB, contrast and analysis the result with result of wavelet transform and ensemble empirical mode decomposition (EEMD). The three evaluation standards (SNR, root mean square error (RMSE) and the correlation coefficient (ρ)) fully proved de-noising advantages of LMS adaptive filter in infrared spectroscopy of breast cancer.

  5. Far-infrared observations of Sagittarius B2: Reconsideration of source structure

    NASA Technical Reports Server (NTRS)

    Thronson, H. A., Jr.; Harper, D. A.

    1985-01-01

    New moderate-angular-resolution far-infrared observations of the Sagittarius B2 star-forming region are presented, discussed, and compared with recent radio molecular and continuum observations of this source. In contrast to previous analyses, its far-infrared spectrum is interpreted as the result of a massive frigid cloud overlying a more-or-less normal infrared source, a natural explanation for the object's previously-noted pecularities. The characteristics derived for the obscuring cloud are similar to those found for the W51 MAIN object. Both sources have high sub-millimeter surface brightness, a high ratio of sub-millimeter to far-infrared flux, and numerous regions of molecular maser emission.

  6. NASA MUST Paper: Infrared Thermography of Graphite/Epoxy

    NASA Technical Reports Server (NTRS)

    Comeaux, Kayla; Koshti, Ajay

    2010-01-01

    The focus of this project is to use Infrared Thermography, a non-destructive test, to detect detrimental cracks and voids beneath the surface of materials used in the space program. This project will consist of developing a simulation model of the Infrared Thermography inspection of the Graphite/Epoxy specimen. The simulation entails finding the correct physical properties for this specimen as well as programming the model for thick voids or flat bottom holes. After the simulation is completed, an Infrared Thermography inspection of the actual specimen will be made. Upon acquiring the experimental test data, an analysis of the data for the actual experiment will occur, which includes analyzing images, graphical analysis, and analyzing numerical data received from the infrared camera. The simulation will then be corrected for any discrepancies between it and the actual experiment. The optimized simulation material property inputs can then be used for new simulation for thin voids. The comparison of the two simulations, the simulation for the thick void and the simulation for the thin void, provides a correlation between the peak contrast ratio and peak time ratio. This correlation is used in the evaluation of flash thermography data during the evaluation of delaminations.

  7. The Infrared Hunter

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    This image composite compares infrared and visible views of the famous Orion nebula and its surrounding cloud, an industrious star-making region located near the hunter constellation's sword. The infrared picture is from NASA's Spitzer Space Telescope, and the visible image is from the National Optical Astronomy Observatory, headquartered in Tucson, Ariz.

    In addition to Orion, two other nebulas can be seen in both pictures. The Orion nebula, or M42, is the largest and takes up the lower half of the images; the small nebula to the upper left of Orion is called M43; and the medium-sized nebula at the top is NGC 1977. Each nebula is marked by a ring of dust that stands out in the infrared view. These rings make up the walls of cavities that are being excavated by radiation and winds from massive stars. The visible view of the nebulas shows gas heated by ultraviolet radiation from the massive stars.

    Above the Orion nebula, where the massive stars have not yet ejected much of the obscuring dust, the visible image appears dark with only a faint glow. In contrast, the infrared view penetrates the dark lanes of dust, revealing bright swirling clouds and numerous developing stars that have shot out jets of gas (green). This is because infrared light can travel through dust, whereas visible light is stopped short by it.

    The infrared image shows light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.

  8. Why Infrared?

    ERIC Educational Resources Information Center

    Harris, J. R.

    1973-01-01

    Discusses applications of techniques developed for the remote sensing of infrared radiation. In addition to military applications, remote sensing has become important in collecting environmental data and detecting ecological problems. (JR)

  9. Pulsed thermography in multiple infrared spectral bands

    NASA Astrophysics Data System (ADS)

    Netzelmann, U.; Abuhamad, M.

    2010-03-01

    Spectrally resolved active thermography by flash pulse excitation was performed in four sub-bands of a mid-wave infrared camera using spectral filtering and in the full long-wave band of a second infrared camera. On zirconia thermal barrier coatings on steel and PVC blocks, spectrally dependent decay rates of the thermal contrast were found. The observed behaviour can be explained by the infrared spectra of the specimens.

  10. Multi-step contrast sensitivity gauge

    SciTech Connect

    Quintana, Enrico C; Thompson, Kyle R; Moore, David G; Heister, Jack D; Poland, Richard W; Ellegood, John P; Hodges, George K; Prindville, James E

    2014-10-14

    An X-ray contrast sensitivity gauge is described herein. The contrast sensitivity gauge comprises a plurality of steps of varying thicknesses. Each step in the gauge includes a plurality of recesses of differing depths, wherein the depths are a function of the thickness of their respective step. An X-ray image of the gauge is analyzed to determine a contrast-to-noise ratio of a detector employed to generate the image.

  11. Infrared Camera

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A sensitive infrared camera that observes the blazing plumes from the Space Shuttle or expendable rocket lift-offs is capable of scanning for fires, monitoring the environment and providing medical imaging. The hand-held camera uses highly sensitive arrays in infrared photodetectors known as quantum well infrared photo detectors (QWIPS). QWIPS were developed by the Jet Propulsion Laboratory's Center for Space Microelectronics Technology in partnership with Amber, a Raytheon company. In October 1996, QWIP detectors pointed out hot spots of the destructive fires speeding through Malibu, California. Night vision, early warning systems, navigation, flight control systems, weather monitoring, security and surveillance are among the duties for which the camera is suited. Medical applications are also expected.

  12. Correlation of infrared reflectance ratios at 2.3 microns/1.6 micron and 1.1 micron/1.6 micron with delta O-18 values delineating fossil hydrothermal systems in the Idaho batholith

    NASA Technical Reports Server (NTRS)

    Gillespie, A. R.; Criss, R. E.

    1983-01-01

    Reflectance ratios from laboratory spectra and airborne multispectral images are found to be strongly correlated with delta O-18 values of granite rocks in the Idaho batholith. The correlation is largely a result of interactions between hot water and rock, which lowered the delta O-18 values of the rocks and produced secondary hydrous material. Maps of the ratio of reflectivities at 2.3 and 1.6 microns should delineate fossil hydrothermal systems and provide estimates of alteration intensity. However, hydrous minerals produced during deuteric alteration or weathering cannot be unambiguously distinguished in remotely sensed images from the products of propylitic alteration without the use of narrow-band scanners. The reflectivity at 1.6 micron is strongly correlated with rock density and may be useful in distinguishing rock types in granitic terranes.

  13. Infrared Thermometer

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Diatek Corporation, San Diego, CA and the Jet Propulsion Lab developed the Diatek Model 7000 aural thermometer which weighs only eight ounces, and measures temperature in less than two seconds using infrared astronomy technology to measure the amount of infrared energy emitted by the eardrum (the same way temperature of stars and planets is measured). This method avoids contact with mucous membranes, virtually eliminating the possibility of cross infection, and permits temperature measurement of newborn, critically ill, or incapacitated patients. Diatek Corporation was purchased by Welch Allyn Inc. The Diatek Model 7000 is now marketed as SureTemp.

  14. Infrared astronomy

    NASA Technical Reports Server (NTRS)

    Gillett, Frederick; Houck, James; Bally, John; Becklin, Eric; Brown, Robert Hamilton; Draine, Bruce; Frogel, Jay; Gatley, Ian; Gehrz, Robert; Hildebrand, Roger

    1991-01-01

    The decade of 1990's presents an opportunity to address fundamental astrophysical issues through observations at IR wavelengths made possible by technological and scientific advances during the last decade. The major elements of recommended program are: the Space Infrared Telescope Facility (SIRTF), the Stratospheric Observatory For Infrared Astronomy (SOFIA) and the IR Optimized 8-m Telescope (IRO), a detector and instrumentation program, the SubMilliMeter Mission (SMMM), the 2 Microns All Sky Survey (2MASS), a sound infrastructure, and technology development programs. Also presented are: perspective, science opportunities, technical overview, project recommendations, future directions, and infrastructure.

  15. Infrared Scanning

    NASA Technical Reports Server (NTRS)

    1987-01-01

    United Scanning Technologies, Inc.'s Infrared thermography is a relatively new noncontact, nondestructive inspection and testing tool which makes temperatures visible to the human eye. Infrared scanning devices produce images that show, by color or black and white shading differences, heat losses through damaged or inadequately insulated walls or roofs. The MISS Aeroscan services are designed to take the guesswork out of industrial roof maintenance and provide companies big savings by identifying the location of moisture damage from roof leaks, effectively targeting maintenance attention.

  16. Advancing High Contrast Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Ammons, M.; Poyneer, L.; GPI Team

    2014-09-01

    A long-standing challenge has been to directly image faint extrasolar planets adjacent to their host suns, which may be ~1-10 million times brighter than the planet. Several extreme AO systems designed for high-contrast observations have been tested at this point, including SPHERE, Magellan AO, PALM-3000, Project 1640, NICI, and the Gemini Planet Imager (GPI, Macintosh et al. 2014). The GPI is the world's most advanced high-contrast adaptive optics system on an 8-meter telescope for detecting and characterizing planets outside of our solar system. GPI will detect a previously unstudied population of young analogs to the giant planets of our solar system and help determine how planetary systems form. GPI employs a 44x44 woofer-tweeter adaptive optics system with a Shack-Hartmann wavefront sensor operating at 1 kHz. The controller uses Fourier-based reconstruction and modal gains optimized from system telemetry (Poyneer et al. 2005, 2007). GPI has an apodized Lyot coronal graph to suppress diffraction and a near-infrared integral field spectrograph for obtaining planetary spectra. This paper discusses current performance limitations and presents the necessary instrumental modifications and sensitivity calculations for scenarios related to high-contrast observations of non-sidereal targets.

  17. Retinex enhancement of infrared images.

    PubMed

    Li, Ying; He, Renjie; Xu, Guizhi; Hou, Changzhi; Sun, Yunyan; Guo, Lei; Rao, Liyun; Yan, Weili

    2008-01-01

    With the ability of imaging the temperature distribution of body, infrared imaging is promising in diagnostication and prognostication of diseases. However the poor quality of the raw original infrared images prevented applications and one of the essential problems is the low contrast appearance of the imagined object. In this paper, the image enhancement technique based on the Retinex theory is studied, which is a process that automatically retrieve the visual realism to images. The algorithms, including Frackle-McCann algorithm, McCann99 algorithm, single-scale Retinex algorithm, multi-scale Retinex algorithm and multi-scale Retinex algorithm with color restoration, are experienced to the enhancement of infrared images. The entropy measurements along with the visual inspection were compared and results shown the algorithms based on Retinex theory have the ability in enhancing the infrared image. Out of the algorithms compared, MSRCR demonstrated the best performance. PMID:19163132

  18. Variability of SO2 and HDO at the cloudtop of Venus from high-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Encrenaz, T.; Greathouse, T.; Richter, M.; DeWitt, C.; Lacy, J.; Widemann, T.; Bézard, B.; Fouchet, T.; Atreya, S.; Sagawa, H.

    2015-10-01

    Since January 2012, we have mapped the SO2 and HDO mixing ratios at the cloudtop of Venus using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the Infrared Telescope Fac ility (IRTF). The HDO maps appear homogeneous over the Venus disk. In contrast, the SO2 maps show strong variations over the disk and within a time scale of two hours. Both molecules show longterm variations with no apparent correlation between the two species.

  19. Infrared Thermometers

    ERIC Educational Resources Information Center

    Schaefers, John

    2006-01-01

    An infrared (IR) thermometer lab offers the opportunity to give science students a chance to measure surface temperatures, utilizing off-the-shelf technology. Potential areas of study include astronomy (exoplanets), electromagnetic spectrum, chemistry, evaporation rates, anatomy, crystal formation, and water or liquids. This article presents one…

  20. Infrared telescope

    NASA Technical Reports Server (NTRS)

    Karr, G. R.; Hendricks, J. B.

    1985-01-01

    The development of the Infrared Telescope for Spacelab 2 is discussed. The design, development, and testing required to interface a stationary superfluid helium dewar with a scanning cryostate capable of operating in the zero-g environment in the space shuttle bay is described.

  1. Infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Lopez, B. A.

    1984-11-01

    Infrared spectroscopic analysis is reviewed. Applications to chemical analysis of preimpregnated carbon fiber materials, including polystyrene spectra, epoxy resin analysis, mineral loads analysis, determination of epoxy groups and identification of spurious organic materials are discussed. The advantages of the method for quality control are pointed out.

  2. [Contrast sensitivity in glaucoma].

    PubMed

    Bartos, D

    1989-05-01

    Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance. PMID:2743444

  3. MERTIS: identifiability of spectral mineralogical features in dependence of the signal to noise ratio

    NASA Astrophysics Data System (ADS)

    Paproth, Carsten; Säuberlich, Thomas

    2011-09-01

    The ESA deep-space mission BepiColombo to planet Mercury will contain the advanced infrared remote sensing instrument MERTIS (MErcury Radiometer and Thermal infrared Imaging Spectrometer). The mission has the goal to explore the planets inner and surface structure and its environment. With MERTIS, investigations of Mercury's surface layer within a spectral range of 7 μm to 14μm shall be conducted to specify and map Mercury's mineralogical composition with a spatial resolution of 500 m. Due to the limited mass and power budget, the used micro-bolometer detector array will only have a temperature-stabilization and will not be cooled. The performance of the instrument is estimated by the theoretical description of the signal to noise ratio and the optics including the Offner spectrometer. The expected signal to noise ratio will be in the order of 100 and is mainly dependent on the surface temperature and the wavelength. The derived theoretical models are used to execute simulations to compute the passage of the infrared radiation of a hypothetical mineralogical surface composition and surface temperature through the optical system of MERTIS. The resulting noisy spectra are used to determine spectral features of the minerals. So it is possible to evaluate the conditions which are necessary to achieve the scientific goals of MERTIS. The intent is to estimate the spectral positions of mineralogical features like the Christiansen feature. This will be difficult because of the low signal to noise ratio and the low contrast of real mineral spectra.

  4. Infrared small target detection based on bilateral filtering algorithm with similarity judgments

    NASA Astrophysics Data System (ADS)

    Li, Yanbei; Li, Yan

    2014-11-01

    Infrared small target detection is part of the key technologies in infrared precision-guided, search and track system. Resulting from the relative distance of the infrared image system and the target is far, the target becomes small, faint and obscure. Furthermore, the interference of background clutter and system noise is intense. To solve the problem of infrared small target detection in a complex background, this paper proposes a bilateral filtering algorithm based on similarity judgments for infrared image background prediction. The algorithm introduces gradient factor and similarity judgment factor into traditional bilateral filtering. The two factors can enhance the accuracy of the algorithm for smooth region. At the same time, spatial proximity coefficients and gray similarity coefficient in the bilateral filtering are all expressed by the first two of McLaughlin expansion, which aiming at reducing the time overhead. Simulation results show that the proposed algorithm can effectively suppress complex background clutter in the infrared image and enhance target signal compared with the improved bilateral filtering algorithm, and it also can improve the signal to noise ratio (SNR) and contrast. Besides, this algorithm can reduce the computation time. In a word, this algorithm has a good background rejection performance.

  5. Infrared floodlight

    DOEpatents

    Levin, Robert E.; English, George J.

    1986-08-05

    An infrared floodlight assembly designed particularly for security purposes and including a heat-conducting housing, a lens secured to the housing to provide a closure therefor, and a floodlight located within (and surrounded by) the housing. The floodlight combines the use of a tungsten halogen light source and dichroic hot and cold mirrors for directing substantially only infrared radiation toward the assembly's forward lens. Visible radiation is absorbed by the housing's interior wall(s) and, optionally, by a filter located between the floodlight and lens. An optional means may be used within the floodlight to reflect all forward radiation back toward the paraboloidal hot mirror or, alternatively, to reflect only visible radiation in this direction. The dichroic hot and cold mirrors preferably each comprise a glass substrate having multiple layers of titanium dioxide and silicon dioxide thereon.

  6. Infrared backscattering

    NASA Technical Reports Server (NTRS)

    Bohren, Craig F.; Nevitt, Timothy J.; Singham, Shermila Brito

    1989-01-01

    All particles in the atmosphere are not spherical. Moreover, the scattering properties of randomly oriented nonspherical particles are not equivalent to those of spherical particles no matter how the term equivalent is defined. This is especially true for scattering in the backward direction and at the infrared wavelengths at which some atmospheric particles have strong absorption bands. Thus calculations based on Mie theory of infrared backscattering by dry or insoluble atmospheric particles are suspect. To support this assertion, it was noted that peaks in laboratory-measured infrared backscattering spectra show appreciable shifts compared with those calculated using Mie theory. One example is ammonium sulfate. Some success was had in modeling backscattering spectra of ammonium sulfate particles using a simple statistical theory called the continuous distribution of ellipsoids (CDE) theory. In this theory, the scattering properties of an ensemble are calculated. Recently a modified version of this theory was applied to measured spectra of scattering by kaolin particles. The particles were platelike, so the probability distribution of ellipsoidal shapes was chosen to reflect this. As with ammonium sulfate, the wavelength of measured peak backscattering is shifted longward of that predicted by Mie theory.

  7. Contrast Intravasation During Hysterosalpingography

    PubMed Central

    Bhoil, Rohit; Sood, Dinesh; Sharma, Tanupriya; Sood, Shilpa; Sharma, Jiten; Kumar, Nitesh; Ahluwalia, Ajay; Parekh, Dipen; Mistry, Kewal A.; Sood, Saurav

    2016-01-01

    Summary Hysterosalpingography is an imaging method to evaluate the endometrial and uterine morphology and fallopian tube patency. Contrast intravasation implies backflow of injected contrast into the adjoining vessels mostly the veins and may be related to factors altering endometrial vascularity and permeability. Radiologists and gynaecologists should be well acquainted with the technique of hysterosalpingography, its interpretation, and intravasation of contrast agents for safer procedure and to minimize the associated complications. PMID:27279925

  8. Isotopic Ratio, Isotonic Ratio, Isobaric Ratio and Shannon Information Uncertainty

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Wei, Hui-Ling

    2014-11-01

    The isoscaling and the isobaric yield ratio difference (IBD) probes, both of which are constructed by yield ratio of fragment, provide cancelation of parameters. The information entropy theory is introduced to explain the physical meaning of the isoscaling and IBD probes. The similarity between the isoscaling and IBD results is found, i.e., the information uncertainty determined by the IBD method equals to β - α determined by the isoscaling (α (β) is the parameter fitted from the isotopic (isotonic) yield ratio).

  9. Toward Critical Contrastive Rhetoric

    ERIC Educational Resources Information Center

    Kubota, Ryuko; Lehner, Al

    2004-01-01

    A traditional approach to contrastive rhetoric has emphasized cultural difference in rhetorical patterns among various languages. Despite its laudable pedagogical intentions to raise teachers' and students' cultural and rhetorical awareness in second language writing, traditional contrastive rhetoric has perpetuated static binaries between English…

  10. Far infrared supplement: Catalog of infrared observations

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1984-01-01

    The Far Infrared Supplement: catalog of infrared observations summarizes all infrared astronomical observations at far infrared wavelengths published in the scientific literature between 1965 and 1982. The Supplement list contains 25% of the observations in the full catalog of infrared observations (C10), and essentially eliminates most visible stars from the listings. The Supplement is more compact than the main Catalog (it does not contain the bibliography and position index of the C10), and is intended for easy reference during astronomical observations.