WorldWideScience

Sample records for polarimetric glucose sensing

  1. Glucose Sensing

    CERN Document Server

    Geddes, Chris D

    2006-01-01

    Topics in Fluorescence Spectroscopy, Glucose Sensing is the eleventh volume in the popular series Topics in Fluorescence Spectroscopy, edited by Drs. Chris D. Geddes and Joseph R. Lakowicz. This volume incorporates authoritative analytical fluorescence-based glucose sensing reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. Glucose Sensing is an essential reference for any lab working in the analytical fluorescence glucose sensing field. All academics, bench scientists, and industry professionals wishing to take advantage of the latest and greatest in the continuously emerging field of glucose sensing, and diabetes care & management, will find this volume an invaluable resource. Topics in Fluorescence Spectroscopy Volume 11, Glucose Sensing Chapters include: Implantable Sensors for Interstitial Fluid Smart Tattoo Glucose Sensors Optical Enzyme-based Glucose Biosensors Plasmonic Glucose Sens...

  2. Nanomaterials in glucose sensing

    CERN Document Server

    Burugapalli, Krishna

    2013-01-01

    The smartness of nano-materials is attributed to their nanoscale and subsequently unique physicochemical properties and their use in glucose sensing has been aimed at improving performance, reducing cost and miniaturizing the sensor and its associated instrumentation. So far, portable (handheld) glucose analysers were introduced for hospital wards, emergency rooms and physicians' offices; single-use strip systems achieved nanolitre sampling for painless and accurate home glucose monitoring; advanced continuous monitoring devices having 2 to 7 days operating life are in clinical and home use; and continued research efforts are being made to develop and introduce increasingly advanced glucose monitoring systems for health as well as food, biotechnology, cell and tissue culture industries. Nanomaterials have touched every aspect of biosensor design and this chapter reviews their role in the development of advanced technologies for glucose sensing, and especially for diabetes. Research shows that overall, nanomat...

  3. On the possibility of noninvasive polarimetric determination of glucose content in skin

    Science.gov (United States)

    Pravdin, A. B.; Spivak, V. A.; Yakovlev, D. A.

    2016-01-01

    Based on real structure and optical properties of the dermis, we analyzed the possibility of polarimetric measurement of glucose content in the skin. It was shown that, at physiological concentrations of glucose in the interstitial fluid, the optical activity of glucose is not manifested in the polarization and optical properties of the tissue, since the optical activity of glucose is almost completely suppressed by the linear birefringence of the dermis.

  4. The Danish polarimetric SAR for remote sensing applications

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Madsen, Søren Nørvang; Dall, Jørgen

    1994-01-01

    Presents the Danish polarimetric SAR system, EMISAR, and the approach taken in the system design to achieve a reliable high performance system. The design and implementation of the antenna system as well as the analog and digital hardware are discussed. The SAR utilises a dual polarised microstri...

  5. Millimeter Wave Polarimetric Radar Remote Sensing of Ice Clouds.

    Science.gov (United States)

    Tang, Chengxian

    Ice clouds play important roles in many practical and theoretical researches. This thesis investigates the electromagnetic scattering properties of ice crystals at 94 and 220 GHz, and polarimetric radar techniques for ice crystal type discrimination and ice mass content estimation. The scattering amplitude matrix is computed for pristine ice crystals of different sizes and from different incidence directions using the Finite Difference Time Domain method. Hexagonal plates, stellar crystals, and hexagonal columns with empirical aspect ratios are considered. The results show that the co-polarized scattering amplitudes are not sensitive to the azimuthal incidence angle but dependent on the polar incidence angle theta as functions of costheta or sintheta raised to a power which depends on particle size. Cross-polarized scattering amplitudes are negligible when the wave polarization is aligned with respect to the particle symmetry axis. Numerical computations are performed to examine the dependence of polarimetric radar parameters on the parameters in the gamma size and Gaussian canting angle distributions, and on radar elevation angle. The computed Mueller matrix elements related to the cross-correlation of the co-polarized and cross-polarized scattering amplitudes are less than 5% of the total irradiance. The linear depolarization ratio, circular depolarization ratio, and dual-frequency ratio are found depolarization ratio, circular depolarization ratio, and dual-frequency ratio are found useful for differentiating between planar ice crystals and columns. Five relationships between ice mass content and polarimetric radar parameters are derived based on numerical simulations representing various assumed ice mass contents and gamma size distributions. The specific differential phase at incidence angles away from the zenith, and effective reflectivity factor together with dual-frequency ratio can provide reasonable estimates for ice mass content. Simulations based on in

  6. Glucose-Sensing in the Reward System

    NARCIS (Netherlands)

    Koekkoek, Laura L.; Mul, Joram D.; la Fleur, Susanne E.

    2017-01-01

    Glucose-sensing neurons are neurons that alter their activity in response to changes in extracellular glucose. These neurons, which are an important mechanism the brain uses to monitor changes in glycaemia, are present in the hypothalamus, where they have been thoroughly investigated. Recently,

  7. Hypothalamic glucose sensing: making ends meet

    Directory of Open Access Journals (Sweden)

    Vanessa eRouth

    2014-12-01

    Full Text Available The neuroendocrine system governs essential survival and homeostatic functions. For example, growth is needed for development. Thermoregulation maintains optimal core temperature in a changing environment. Reproduction ensures species survival. Stress and immune responses enable an organism to overcome external and internal threats. The circadian system regulates arousal and sleep such that vegetative and active functions do not overlap. All of these functions require a significant portion of the body’s energy. As the integrator of the neuroendocrine system, the hypothalamus carefully assesses the energy status of the body in order to appropriately partition resources to provide for each system without compromising the others. While doing so the hypothalamus must ensure that adequate glucose levels are preserved for brain function since glucose is the primary fuel of the brain. To this end, the hypothalamus contains specialized glucose sensing neurons which are scattered throughout the nuclei controlling distinct neuroendocrine functions. We hypothesize that these neurons play a key role in enabling the hypothalamus to partition energy to meet these peripheral survival needs without endangering the brain’s glucose supply. The goal of this review is to describe the varied mechanisms underlying glucose sensing in neurons within discrete hypothalamic nuclei. We will then evaluate the way in which peripheral energy status regulates glucose sensitivity. For example, during energy deficit such as fasting specific hypothalamic glucose sensing neurons become sensitized to decreased glucose. This increases the gain of the information relay when glucose availability is a greater concern for the brain. Finally, changes in glucose sensitivity under pathological conditions (e.g., recurrent insulin-hypoglycemia, diabetes will be addressed. The overall goal of this review is to place glucose sensing neurons within the context of hypothalamic control of

  8. Design and development of a microwave multifrequency polarimetric scatterometer for biosphere remote sensing

    International Nuclear Information System (INIS)

    Stjernman, A.

    1995-05-01

    The main topic of this research report is the design and development of a multifrequency, polarimetric scatterometer for biosphere remote sensing. The system was developed using a standard HP network analyzer, a crossed log-periodic dipole antenna and a reflector. The scatterometer functions in a linear polarization basis between the L- and X-bands and gathers full-polarimetric information. The standard S-parameter measurements using the network analyzer were related to surface and volume scattering coefficients of rough surface, snow cover and vegetation media. The scatterometer measurements were carried out in the frequency domain to make use of narrow band filters in the receiver chain. The fast Fourier transform was used to convert the frequency domain measurements to the time domain. The range resolution of the system was 20 cm; azimuthal and elevation resolutions are determined by the antenna beam widths. Range side lobes were reduced by making use of appropriate weighting (Kaiser-Bessel window) functions. The accuracy of target characterization depends on the quality of scatterometer calibration. A novel technique to estimate the absolute gain and crosstalk of the radar system was developed. Using a distortion matrix approach, the cross-polarization response of the system was improved by 10 to 25 dB. The radar measurements were validated by comparing point target radar observations with the corresponding theoretical values. Also, measurements of fading decorrelation distance and decorrelation bandwidth or rough surfaces were in good agreement with the theory. Backscatter observations of vegetation and snow cover were comparable to earlier published values for a similar environment. 50 refs, 56 figs, 1 tab

  9. Design and development of a microwave multifrequency polarimetric scatterometer for biosphere remote sensing

    Energy Technology Data Exchange (ETDEWEB)

    Stjernman, A.

    1995-05-01

    The main topic of this research report is the design and development of a multifrequency, polarimetric scatterometer for biosphere remote sensing. The system was developed using a standard HP network analyzer, a crossed log-periodic dipole antenna and a reflector. The scatterometer functions in a linear polarization basis between the L- and X-bands and gathers full-polarimetric information. The standard S-parameter measurements using the network analyzer were related to surface and volume scattering coefficients of rough surface, snow cover and vegetation media. The scatterometer measurements were carried out in the frequency domain to make use of narrow band filters in the receiver chain. The fast Fourier transform was used to convert the frequency domain measurements to the time domain. The range resolution of the system was 20 cm; azimuthal and elevation resolutions are determined by the antenna beam widths. Range side lobes were reduced by making use of appropriate weighting (Kaiser-Bessel window) functions. The accuracy of target characterization depends on the quality of scatterometer calibration. A novel technique to estimate the absolute gain and crosstalk of the radar system was developed. Using a distortion matrix approach, the cross-polarization response of the system was improved by 10 to 25 dB. The radar measurements were validated by comparing point target radar observations with the corresponding theoretical values. Also, measurements of fading decorrelation distance and decorrelation bandwidth or rough surfaces were in good agreement with the theory. Backscatter observations of vegetation and snow cover were comparable to earlier published values for a similar environment. 50 refs, 56 figs, 1 tab.

  10. Airborn Ku-band polarimetric radar remote sensing of terrestrial snow cover

    Science.gov (United States)

    Simon H. Yueh; Steve J. Dinardo; Ahmed Akgiray; Richard West; Donald W. Cline; Kelly Elder

    2009-01-01

    Characteristics of the Ku-band polarimetric scatterometer (POLSCAT) data acquired from five sets of aircraft flights in the winter months of 2006-2008 for the second Cold Land Processes Experiment (CLPX-II) in Colorado are described in this paper. The data showed the response of the Ku-band radar echoes to snowpack changes for various types of background vegetation in...

  11. Ratiometric glucose sensing based on fluorescent oxygen films and glucose oxidase

    Directory of Open Access Journals (Sweden)

    Fengyu Su

    2017-06-01

    Full Text Available A new two-layer sensor film was constructed for sensing glucose based on glucose oxidase and oxygen sensing material. The first layer of film containing the oxygen sensor and intra-reference material was polymerized, then the second layer of glucose oxidase and glutaraldehyde was formed on the oxygen sensor layer. The two-layer sensor film has a resolution up to 0.05 mM and a detection range from 0 to 5 mM to glucose. The effects of pH and temperature on the sensing performance were systematically investigated. The selective detection of glucose among other monosaccharides, such as fructose, mannose and galactose indicated that the sensing film has excellent selectivity. The prepared sensor was successfully applied for glucose sample detection of glucose concentration in artificial tears.

  12. Conditions With High Intracellular Glucose Inhibit Sensing Through Glucose Sensor Snf3 in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Karhumaa, Kaisa; Wu, B.Q.; Kielland-Brandt, Morten

    2010-01-01

    as for amino acids. An alternating-access model of the function of transporter-like sensors has been previously suggested based on amino acid sensing, where intracellular ligand inhibits binding of extracellular ligand. Here we studied the effect of intracellular glucose on sensing of extracellular glucose...... through the transporter-like sensor Snf3 in yeast. Sensing through Snf3 was determined by measuring degradation of Mth1 protein. High intracellular glucose concentrations were achieved by using yeast strains lacking monohexose transporters which were grown on maltose. The apparent affinity...... of extracellular glucose to Snf3 was measured for cells grown in non-fermentative medium or on maltose. The apparent affinity for glucose was lowest when the intracellular glucose concentration was high. The results conform to an alternating-access model for transporter-like sensors. J. Cell. Biochem. 110: 920...

  13. Ground-Based Polarimetric Remote Sensing of Dust Aerosol Properties in Chinese Deserts near Hexi Corridor

    Directory of Open Access Journals (Sweden)

    Hua Xu

    2014-01-01

    Full Text Available One-year observation of dust aerosol properties near Hexi Corridor was obtained from polarimetric measurements by ground-based sunphotometer in the county of Minqin in northwestern China from March 2012 to February 2013. We observed an annual mean AOD of 0.22±0.22 at 0.50 μm and Ångström exponents of 0.1–1.0 fitting a bimode normal distribution centered at 0.18 and 0.50, respectively. The effective radii of fine (0.13–0.17 μm and coarse (2.49–3.49 μm modes were found stable at all seasons together with the appearance of a third mode of particle radius at 0.4–1.0 μm when AOD was larger than 0.6. It is noticeable that the real (1.5–1.7 and imaginary (0.0005 to 0.09 parts of complex refractive indices were higher than other studies performed in other desert regions of China, while single scattering albedo was relatively lower (~0.84–0.89 at wavelengths of 0.44, 0.67, 0.87, and 1.02 μm. This is partially due to calcite or hematite in the soil in Minqin or the influence of anthropogenic aerosols containing carbon. Moreover, from our novel polarimetric measurement, the scattering phase function (F11 and degree of linear polarization for incident unpolarized light (-F12/F11 of dust aerosols were also obtained within this deserted area.

  14. Nervous glucose sensing regulates postnatal β cell proliferation and glucose homeostasis

    OpenAIRE

    Tarussio, David; Metref, Salima; Seyer, Pascal; Mounien, Lourdes; Vallois, David; Magnan, Christophe; Foretz, Marc; Thorens, Bernard

    2013-01-01

    How glucose sensing by the nervous system impacts the regulation of β cell mass and function during postnatal development and throughout adulthood is incompletely understood. Here, we studied mice with inactivation of glucose transporter 2 (Glut2) in the nervous system (NG2KO mice). These mice displayed normal energy homeostasis but developed late-onset glucose intolerance due to reduced insulin secretion, which was precipitated by high-fat diet feeding. The β cell mass of adult NG2KO mice wa...

  15. Nervous glucose sensing regulates postnatal beta cell proliferation and glucose homeostasis

    OpenAIRE

    Tarussio, David; Metref, Salima; Seyer, Pascal; Mounien, Lourdes; Vallois, David; Magnan, Christophe; Foretz, Marc; Thorens, Bernard

    2014-01-01

    How glucose sensing by the nervous system impacts the regulation of â cell mass and function during postnatal development and throughout adulthood is incompletely understood. Here we studied mice with inactivation of glucose transporter 2 (Glut2) in the nervous system (NG2KO mice). These mice displayed normal energy homeostasis but developed late onset glucose intolerance due to reduced insulin secretion which was precipitated by high fat diet feeding. The â cell mass of adult NG2KO mice was ...

  16. SERS Nanosensors for in Vivo Glucose Sensing

    Science.gov (United States)

    2017-09-01

    monitoring, medical device W81XWH-16-1-0376 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF...SERS, Raman scattering, spectroscopy, hydrogel, microneedle array, continuous glucose monitoring, medical device 3. ACCOMPLISHMENTS Major...stronger particle-particle interaction. Therefore, the electrostatic attraction between particles must be overcome to bring the particles closer to the

  17. Regression Methods for Ophthalmic Glucose Sensing Using Metamaterials

    Directory of Open Access Journals (Sweden)

    Philipp Rapp

    2011-01-01

    Full Text Available We present a novel concept for in vivo sensing of glucose using metamaterials in combination with automatic learning systems. In detail, we use the plasmonic analogue of electromagnetically induced transparency (EIT as sensor and evaluate the acquired data with support vector machines. The metamaterial can be integrated into a contact lens. This sensor changes its optical properties such as reflectivity upon the ambient glucose concentration, which allows for in situ measurements in the eye. We demonstrate that estimation errors below 2% at physiological concentrations are possible using simulations of the optical properties of the metamaterial in combination with an appropriate electrical circuitry and signal processing scheme. In the future, functionalization of our sensor with hydrogel will allow for a glucose-specific detection which is insensitive to other tear liquid substances providing both excellent selectivity and sensitivity.

  18. Glucose- and nitrogen sensing and regulatory mechanisms in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Rødkaer, Steven V; Færgeman, Nils J.

    2014-01-01

    steps and by numerous different regulators. As numerous of these regulating proteins, biochemical mechanisms, and cellular pathways are evolutionary conserved, complex biochemical information relevant to humans can be obtained by studying simple organisms. Thus, the yeast Saccharomyces cerevisiae has...... been recognized as a powerful model system to study fundamental biochemical processes. In the present review, we highlight central signaling pathways and molecular circuits conferring nitrogen- and glucose sensing in S. cerevisiae....

  19. A novel reagentless sensing system for measuring glucose based on the galactose/glucose-binding protein

    Science.gov (United States)

    Salins, L. L.; Ware, R. A.; Ensor, C. M.; Daunert, S.

    2001-01-01

    The galactose/glucose-binding protein (GBP) is synthesized in the cytoplasm of Escherichia coli in a precursor form and exported into the periplasmic space upon cleavage of a 23-amino-acid leader sequence. GBP binds galactose and glucose in a highly specific manner. The ligand induces a hinge motion in GBP and the resultant protein conformational change constitutes the basis of the sensing system. The mglB gene, which codes for GBP, was isolated from the chromosome of E. coli using the polymerase chain reaction (PCR). Since wild-type GBP lacks cysteines in its structure, introducing this amino acid by site-directed mutagenesis ensures single-label attachment at specific sites with a sulfhydro-specific fluorescent probe. Site-directed mutagenesis by overlap extension PCR was performed to prepare three different mutants to introduce a single cysteine residue at positions 148, 152, and 182. Since these residues are not involved in ligand binding and since they are located at the edge of the binding cleft, they experience a significant change in environment upon binding of galactose or glucose. The sensing system strategy is based on the fluorescence changes of the probe as the protein undergoes a structural change on binding. In this work a reagentless sensing system has been rationally designed that can detect submicromolar concentrations of glucose. The calibration plots have a linear working range of three orders of magnitude. Although the system can sense galactose as well, this epimer is not a potential interfering substance since its concentration in blood is negligible. Copyright 2001 Academic Press.

  20. Sweet taste receptor in the hypothalamus: a potential new player in glucose sensing in the hypothalamus.

    Science.gov (United States)

    Kohno, Daisuke

    2017-07-01

    The hypothalamic feeding center plays an important role in energy homeostasis. The feeding center senses the systemic energy status by detecting hormone and nutrient levels for homeostatic regulation, resulting in the control of food intake, heat production, and glucose production and uptake. The concentration of glucose is sensed by two types of glucose-sensing neurons in the feeding center: glucose-excited neurons and glucose-inhibited neurons. Previous studies have mainly focused on glucose metabolism as the mechanism underlying glucose sensing. Recent studies have indicated that receptor-mediated pathways also play a role in glucose sensing. This review describes sweet taste receptors in the hypothalamus and explores the role of sweet taste receptors in energy homeostasis.

  1. Optical polarimetry for noninvasive glucose sensing enabled by Sagnac interferometry.

    Science.gov (United States)

    Winkler, Amy M; Bonnema, Garret T; Barton, Jennifer K

    2011-06-10

    Optical polarimetry is used in pharmaceutical drug testing and quality control for saccharide-containing products (juice, honey). More recently, it has been proposed as a method for noninvasive glucose sensing for diabetic patients. Sagnac interferometry is commonly used in optical gyroscopes, measuring minute Doppler shifts resulting from mechanical rotation. In this work, we demonstrate that Sagnac interferometers are also sensitive to optical rotation, or the rotation of linearly polarized light, and are therefore useful in optical polarimetry. Results from simulation and experiment show that Sagnac interferometers are advantageous in optical polarimetry as they are insensitive to net linear birefringence and alignment of polarization components.

  2. The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI: a new tool for aerosol and cloud remote sensing

    Directory of Open Access Journals (Sweden)

    D. J. Diner

    2013-08-01

    Full Text Available The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI is an eight-band (355, 380, 445, 470, 555, 660, 865, 935 nm pushbroom camera, measuring polarization in the 470, 660, and 865 nm bands, mounted on a gimbal to acquire multiangular observations over a ±67° along-track range. The instrument has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. AirMSPI employs a photoelastic modulator-based polarimetric imaging technique to enable accurate measurements of the degree and angle of linear polarization in addition to spectral intensity. A description of the AirMSPI instrument and ground data processing approach is presented. Example images of clear, hazy, and cloudy scenes over the Pacific Ocean and California land targets obtained during flights between 2010 and 2012 are shown, and quantitative interpretations of the data using vector radiative transfer theory and scene models are provided to highlight the instrument's capabilities for determining aerosol and cloud microphysical properties and cloud 3-D spatial distributions. Sensitivity to parameters such as aerosol particle size distribution, ocean surface wind speed and direction, cloud-top and cloud-base height, and cloud droplet size is discussed. AirMSPI represents a major step toward realization of the type of imaging polarimeter envisioned to fly on NASA's Aerosol-Cloud-Ecosystem (ACE mission in the next decade.

  3. Carbon dots from tryptophan doped glucose for peroxynitrite sensing

    Energy Technology Data Exchange (ETDEWEB)

    Simões, Eliana F.C. [CIQ-UP, Grupo de Ciências Biológicas e Bioanalíticas, Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); CIQ-UP, Departamento de Química, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal); Esteves da Silva, Joaquim C.G. [CIQ-UP, Departamento de Química, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal); Leitão, João M.M., E-mail: jleitao@ff.uc.pt [CIQ-UP, Grupo de Ciências Biológicas e Bioanalíticas, Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal)

    2014-12-10

    Highlights: • Synthesis of tryptophan doped carbon dots. • Experimental design optimization of the tryptophan doped carbon dots synthesis. • Fluorescence sensing of peroxynitrite by tryptophan doped carbon dots. • Peroxynitrite quantification in serum samples by tryptophan doped carbon dots. - Abstract: Tryptophan doped carbon dots (Trp-CD) were microwave synthesized. The optimum conditions of synthesizing of the Trp-CD were established by response surface multivariate optimization methodologies and were the following: 2.5 g of glucose and 300 mg of tryptophan diluted in 15 mL of water exposed for 5 min to a microwave radiation of 700 W. Trp-CD have an average size of 20 nm, were fluorescent with a quantum yield of 12.4% and the presence of peroxynitrite anion (ONOO{sup −}) provokes quenching of the fluorescence. The evaluated analytical methodology for ONOO{sup −} detection shows a linear response range from 5 to 25 μM with a limit of detection of 1.5 μM and quantification of 4.9 μM. The capability of the ONOO{sup −} quantification was evaluated in standard solutions and in fortified serum samples.

  4. Utilizing hyaluronic acid as a versatile platform for fluorescence resonance energy transfer-based glucose sensing.

    Science.gov (United States)

    Ge, Minghao; Bai, Pengli; Chen, Mingli; Tian, Jingjing; Hu, Jun; Zhi, Xu; Yin, Huancai; Yin, Jian

    2018-03-01

    Here, we utilized the ultrasonic emulsification technique to generate hyaluronic acid microspheres incorporating a fluorescence-based glucose biosensor. We synthesized a novel lanthanide ion luminophore based on Eu 3+ . Eu sulfosuccinimidyl dextran (Eu-dextran) and Alexa Fluor 647 sulfosuccinimidyl-ConA (Alexa Fluor 647-ConA) were encapsulated in hyaluronic acid hydrogel to generate microspheres. Glucose sensing was carried out using a fluorescence resonance energy transfer (FRET)-based assay principle. A proportional fluorescence intensity increase was found within a 0.5-10-mM glucose concentration range. The glucose-sensing strategy showed an excellent tolerance for potential interferents. Meanwhile, the fluorescent signal of hyaluronic acid microspheres was very stable after testing for 72 h in glucose solution. Overall, hyaluronic acid microspheres encapsulating sensing biomolecules offer a stable and biocompatible biosensor for a variety of applications including cell culture systems, tissue engineering, detection of blood glucose, etc. Graphical abstract We report an ingenious biosensor encapsulated in hyaluronic acid microspheres for monitoring of glucose. Glucose sensing is carried out using a fluorescence resonance energy transfer-based assay principle with a novel lanthanide ions luminophore. The glucose detection system has excellent biocompatibility and stability for monitoring of glucose.

  5. Polarimetric Multispectral Imaging Technology

    Science.gov (United States)

    Cheng, L.-J.; Chao, T.-H.; Dowdy, M.; Mahoney, C.; Reyes, G.

    1993-01-01

    The Jet Propulsion Laboratory is developing a remote sensing technology on which a new generation of compact, lightweight, high-resolution, low-power, reliable, versatile, programmable scientific polarimetric multispectral imaging instruments can be built to meet the challenge of future planetary exploration missions. The instrument is based on the fast programmable acousto-optic tunable filter (AOTF) of tellurium dioxide (TeO2) that operates in the wavelength range of 0.4-5 microns. Basically, the AOTF multispectral imaging instrument measures incoming light intensity as a function of spatial coordinates, wavelength, and polarization. Its operation can be in either sequential, random access, or multiwavelength mode as required. This provides observation flexibility, allowing real-time alternation among desired observations, collecting needed data only, minimizing data transmission, and permitting implementation of new experiments. These will result in optimization of the mission performance with minimal resources. Recently we completed a polarimetric multispectral imaging prototype instrument and performed outdoor field experiments for evaluating application potentials of the technology. We also investigated potential improvements on AOTF performance to strengthen technology readiness for applications. This paper will give a status report on the technology and a prospect toward future planetary exploration.

  6. Near-infrared fluorescence glucose sensing based on glucose/galactose-binding protein coupled to 651-Blue Oxazine

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Faaizah; Pickup, John C., E-mail: john.pickup@kcl.ac.uk

    2013-08-30

    Highlights: •We showed that the NIR fluorophore, 651-Blue Oxazine, is solvatochromic (polarity sensitive). •Blue Oxazine was covalently attached to mutants of glucose/galactose-binding protein (GBP). •Fluorescence intensity of GBP-Blue Oxazine increased with addition of glucose. •Fluorescence from bead-immobilised GBP-Blue Oxazine was detectable through skin in vitro. •This shows proof-of-concept for non-invasive glucose sensing using GBP-Blue Oxazine. -- Abstract: Near-infrared (NIR) fluorescent dyes that are environmentally sensitive or solvatochromic are useful tools for protein labelling in in vivo biosensor applications such as glucose monitoring in diabetes since their spectral properties are mostly independent of tissue autofluorescence and light scattering, and they offer potential for non-invasive analyte sensing. We showed that the fluorophore 651-Blue Oxazine is polarity-sensitive, with a marked reduction in NIR fluorescence on increasing solvent polarity. Mutants of glucose/galactose-binding protein (GBP) used as the glucose receptor were site-specifically and covalently labelled with Blue Oxazine using click chemistry. Mutants H152C/A213R and H152C/A213R/L238S showed fluorescence increases of 15% and 21% on addition of saturating glucose concentrations and binding constants of 6 and 25 mM respectively. Fluorescence responses to glucose were preserved when GBP-Blue Oxazine was immobilised to agarose beads, and the beads were excited by NIR light through a mouse skin preparation studied in vitro. We conclude GBP-Blue Oxazine shows proof-of-concept as a non-invasive continuous glucose sensing system.

  7. Construction of a novel glucose-sensing molecule based on a substrate-binding protein for intracellular sensing.

    Science.gov (United States)

    Sakaguchi-Mikami, Akane; Taniguchi, Akiyoshi; Sode, Koji; Yamazaki, Tomohiko

    2011-04-01

    A novel transcriptional regulator responding to glucose was designed with a substrate-binding protein (SBP) as a probe towards intracellular sensing system for glucose in mammalian cells. A chimeric protein of an SBP for glucose (GBP) and a LacI-type regulator, LacI (SLCP(GL) ), was designed, constructed and characterized using Escherichia coli recombinant protein. We report that SLCP(GL) has a glucose-specific binding ability and an operator-sequence specific DNA-binding ability. The loss of its DNA-binding ability in the presence of glucose suggests a role as a transcriptional regulator in vitro. The glucose-dependent gene regulation function of SLCP(GL) in cells was investigated using mammalian cells co-transfected with SLCP(GL) and Lac operator-fused luciferase gene constructs. The luciferase activity of the transfected cells increased with the glucose concentration in the medium, showing that the expression of the luciferase gene is regulated by SLCP(GL) , which can dissociate from DNA in a glucose concentration-dependent manner. Therefore, we demonstrated that SLCP(GL) functions as a glucose-sensitive transcriptional regulator in mammalian cells. These results reveal the possibility of developing an SBP-based regulator as a probe of intracellular sensing and gene regulation system for mammalian cells in response to a desired ligands depending on the SBP ligand specificity. Copyright © 2010 Wiley Periodicals, Inc.

  8. Closed-loop controlled noninvasive ultrasonic glucose sensing and insulin delivery

    Science.gov (United States)

    Park, Eun-Joo; Werner, Jacob; Jaiswal, Devina; Smith, Nadine Barrie

    2010-03-01

    To prevent complications in diabetes, the proper management of blood glucose levels is essential. Previously, ultrasonic transdermal methods using a light-weight cymbal transducer array has been studied for noninvasive methods of insulin delivery for Type-1 diabetes and glucose level monitoring. In this study, the ultrasound systems of insulin delivery and glucose sensing have been combined by a feedback controller. This study was designed to show the feasibility of the feedback controlled ultrasound system for the noninvasive glucose control. For perspective human application, in vivo experiments were performed on large animals that have a similar size to humans. Four in vivo experiments were performed using about 200 lbs pigs. The cymbal array of 3×3 pattern has been used for insulin delivery at 30 kHz with the spatial-peak temporal-peak intensity (Isptp) of 100 mW/cm2. For glucose sensing, a 2×2 array was operated at 20 kHz with Isptp = 100 mW/cm2. Based on the glucose level determined by biosensors after the ultrasound exposure, the ultrasound system for the insulin delivery was automatically operated. The glucose level of 115 mg/dl was set as a reference value for operating the insulin delivery system. For comparison, the glucose levels of blood samples collected from the ear vein were measured by a commercial glucose meter. Using the ultrasound system operated by the close-loop, feed-back controller, the glucose levels of four pigs were determined every 20 minutes and continuously controlled for 120 minutes. In comparison to the commercial glucose meter, the glucose levels determined by the biosensor were slightly higher. The results of in vivo experiments indicate the feasibility of the feedback controlled ultrasound system using the cymbal array for noninvasive glucose sensing and insulin delivery. Further studies on the extension of the glucose control will be continued for the effective method of glucose control.

  9. Hypothalamic glucose-sensing: role of Glia-to-neuron signaling.

    Science.gov (United States)

    Tonon, M C; Lanfray, D; Castel, H; Vaudry, H; Morin, F

    2013-12-01

    The hypothalamus senses hormones and nutrients in order to regulate energy balance. In particular, detection of hypothalamic glucose levels has been shown to regulate both feeding behavior and peripheral glucose homeostasis, and impairment of this regulatory system is believed to be involved in the development of obesity and diabetes. Several data clearly demonstrate that glial cells are key elements in the perception of glucose, constituting with neurons a "glucose-sensing unit". Characterization of this interplay between glia and neurons represents an exciting challenge, and will undoubtedly contribute to identify new candidates for therapeutic intervention. The purpose of this review is to summarize the current data that stress the importance of glia in central glucose-sensing. The nature of the glia-to-neuron signaling is discussed, with a special focus on the endozepine ODN, a potent anorexigenic peptide that is highly expressed in hypothalamic glia. © Georg Thieme Verlag KG Stuttgart · New York.

  10. Efficient Estimation of Spectral Moments and the Polarimetric Variables on Weather Radars, Sonars, Sodars, Acoustic Flow Meters, Lidars, and Similar Active Remote Sensing Instruments

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method for estimation of Doppler spectrum, its moments, and polarimetric variables on pulsed weather radars which uses over sampled echo components at a rate...

  11. Glucose sensing by carotid body glomus cells: potential implications in disease

    Directory of Open Access Journals (Sweden)

    Lin eGao

    2014-10-01

    Full Text Available The carotid body (CB is a key chemoreceptor organ in which glomus cells sense changes in blood O2, CO2, and pH levels. CB glomus cells have also been found to detect hypoglycemia in both non-primate mammals and humans. O2 and low-glucose responses share a common final pathway involving membrane depolarization, extracellular calcium influx, increase in cytosolic calcium concentration, and neurotransmitter secretion, which stimulates afferent sensory fibers to evoke sympathoadrenal activation. On the other hand, hypoxia and low glucose induce separate signal transduction pathways. Unlike O2 sensing, the response of the CB to low glucose is not altered by rotenone, with the low glucose-activated background cationic current unaffected by hypoxia. Responses of the CB to hypoglycemia and hypoxia can be potentiated by each other. The counter-regulatory response to hypoglycemia by the CB is essential for the brain, an organ that is particularly sensitive to low glucose. CB glucose sensing could be altered in diabetic patients, particularly those under insulin treatment, as well as in other medical conditions such as sleep apnea or obstructive pulmonary diseases, where chronic hypoxemia presents with plastic modifications in CB structure and function. The current review will focus on the following main aspects: 1 the CB as a low glucose sensor in both in vitro and in vivo models; 2 molecular and ionic mechanisms of low glucose sensing by glomus cells, 3 the interplay between low glucose and O2 sensing in CB, and 4 the role of CB low glucose sensing in the pathophysiology of cardiorespiratory and metabolic diseases, and how this may serve as a potential therapeutic target.

  12. Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Jon Stefan Hansen

    2013-12-01

    Full Text Available Continuous glucose monitoring (CGM is crucial in order to avoid complications caused by change in blood glucose for patients suffering from diabetes mellitus. The long-term consequences of high blood glucose levels include damage to the heart, eyes, kidneys, nerves and other organs, among others, caused by malign glycation of vital protein structures. Fluorescent monitors based on arylboronic acids are promising candidates for optical CGM, since arylboronic acids are capable of forming arylboronate esters with 1,2-cis-diols or 1,3-diols fast and reversibly, even in aqueous solution. These properties enable arylboronic acid dyes to provide immediate information of glucose concentrations. Thus, the replacement of the commonly applied semi-invasive and non-invasive techniques relying on glucose binding proteins, such as concanavalin A, or enzymes, such as glucose oxidase, glucose dehydrogenase and hexokinases/glucokinases, might be possible. The recent progress in the development of fluorescent arylboronic acid dyes will be emphasized in this review.

  13. Sensing of Salivary Glucose Using Nano-Structured Biosensors.

    Science.gov (United States)

    Du, Yunqing; Zhang, Wenjun; Wang, Ming L

    2016-03-17

    The anxiety and pain associated with frequent finger pricking has always been troublesome for diabetics measuring blood glucose (BG) in their daily lives. For this reason, a reliable glucose monitoring system that allows noninvasive measurements is highly desirable. Our main objective is to develop a biosensor that can detect low-level glucose in saliva (physiological range 0.5-20 mg/dL). Salivary glucose (SG) sensors were built using a layer-by-layer self-assembly of single-walled carbon nanotubes, chitosan, gold nanoparticles, and glucose oxidase onto a screen-printed platinum electrode. An electrochemical method was utilized for the quantitative detection of glucose in both buffer solution and saliva samples. A standard spectrophotometric technique was used as a reference method to validate the glucose content of each sample. The disposable glucose sensors have a detection limit of 0.41 mg/dL, a sensitivity of 0.24 μA·s·dL·mg(-1), a linear range of 0.5-20 mg/dL in buffer solution, and a response time of 30 s. A study of 10 healthy subjects was conducted, and SG levels between 1.1 to 10.1 mg/dL were successfully detected. The results revealed that the noninvasive SG monitoring could be an alternative for diabetes self-management at home. This paper is not intended to replace regular BG tests, but to study SG itself as an indicator for the quality of diabetes care. It can potentially help patients control and monitor their health conditions, enabling them to comply with prescribed treatments for diabetes.

  14. Sensing of Salivary Glucose Using Nano-Structured Biosensors

    Science.gov (United States)

    Du, Yunqing; Zhang, Wenjun; Wang, Ming L.

    2016-01-01

    The anxiety and pain associated with frequent finger pricking has always been troublesome for diabetics measuring blood glucose (BG) in their daily lives. For this reason, a reliable glucose monitoring system that allows noninvasive measurements is highly desirable. Our main objective is to develop a biosensor that can detect low-level glucose in saliva (physiological range 0.5–20 mg/dL). Salivary glucose (SG) sensors were built using a layer-by-layer self-assembly of single-walled carbon nanotubes, chitosan, gold nanoparticles, and glucose oxidase onto a screen-printed platinum electrode. An electrochemical method was utilized for the quantitative detection of glucose in both buffer solution and saliva samples. A standard spectrophotometric technique was used as a reference method to validate the glucose content of each sample. The disposable glucose sensors have a detection limit of 0.41 mg/dL, a sensitivity of 0.24 μA·s·dL·mg−1, a linear range of 0.5–20 mg/dL in buffer solution, and a response time of 30 s. A study of 10 healthy subjects was conducted, and SG levels between 1.1 to 10.1 mg/dL were successfully detected. The results revealed that the noninvasive SG monitoring could be an alternative for diabetes self-management at home. This paper is not intended to replace regular BG tests, but to study SG itself as an indicator for the quality of diabetes care. It can potentially help patients control and monitor their health conditions, enabling them to comply with prescribed treatments for diabetes. PMID:26999233

  15. Hepatic glucose sensing via the CREB coactivator CRTC2.

    Science.gov (United States)

    Dentin, Renaud; Hedrick, Susan; Xie, Jianxin; Yates, John; Montminy, Marc

    2008-03-07

    Chronic hyperglycemia contributes to the development of diabetes-associated complications. Increases in the concentration of circulating glucose activate the hexosamine biosynthetic pathway (HBP) and promote the O-glycosylation of proteins by O-glycosyl transferase (OGT). We show that OGT triggered hepatic gluconeogenesis through the O-glycosylation of the transducer of regulated cyclic adenosine monophosphate response element-binding protein (CREB) 2 (TORC2 or CRTC2). CRTC2 was O-glycosylated at sites that normally sequester CRTC2 in the cytoplasm through a phosphorylation-dependent mechanism. Decreasing amounts of O-glycosylated CRTC2 by expression of the deglycosylating enzyme O-GlcNAcase blocked effects of glucose on gluconeogenesis, demonstrating the importance of the HBP in the development of glucose intolerance.

  16. Closed-Loop Noninvasive Ultrasound Glucose Sensing and Insulin Delivery

    Science.gov (United States)

    2006-09-01

    They have always supported me in my education and I owe my success to them. Esta sequnda tesis es para ustedes y gracias por siempre creer en mi. xi...Glucose monitoring: state of the art and future possibilities,” Medical Engineering Physics, vol.18, no.4, 196, pp.273-288. [21] K. Ogata, Modern

  17. Glucose Sensing Using Capacitive Biosensor Based on Polyvinylidene Fluoride Thin Film

    Directory of Open Access Journals (Sweden)

    Ambran Hartono

    2018-01-01

    Full Text Available A polyvinylidene fluoride (PVDF film-based capacitive biosensor was developed for glucose sensing. This device consists of a PVDF film sandwiched between two electrodes. A capacitive biosensor measures the dielectric properties of the dielectric layers at the interface between the electrolyte and the electrode. A glucose oxidase (GOx enzyme was immobilized onto the electrode to oxidize glucose. In practice, the biochemical reaction of glucose with the GOx enzyme generates free electron carriers. Consequently, the potential difference between the electrodes is increased, resulting in a measurable voltage output of the biosensor. The device was tested for various glucose concentrations in the range of 0.013 to 5.85 M, and various GOx enzyme concentrations between 4882.8 and 2.5 million units/L. We found that the sensor output increased with increasing glucose concentration up to 5.85 M. These results indicate that the PVDF film-based capacitive biosensors can be properly applied to glucose sensing and provide opportunities for the low-cost fabrication of glucose-based biosensors based on PVDF materials.

  18. Functional CuO Microstructures for Glucose Sensing

    Science.gov (United States)

    Ali, Gulzar; Tahira, Aneela; Mallah, Arfana Begum; Mallah, Sarfraz Ahmed; Ibupoto, Akila; Khand, Aftab Ahmed; Baradi, Waryani; Willander, Magnus; Yu, Cong; Ibupoto, Zafar Hussain

    2018-02-01

    CuO microstructures are produced in the presence of water-soluble amino acids by hydrothermal method. The used amino acids include isoleucine, alpha alanine, and arginine as a soft template and are used for tuning the morphology of CuO nanostructures. The crystalline and morphological investigations were carried out by x-ray diffraction (XRD) and scanning electron microscopy techniques. The XRD study has shown that CuO material obtained in the presence of different amino acids is of high purity and all have the same crystal phase. The CuO microstructures prepared in the presence of arginine were used for the development of sensitive and selective glucose biosensor. The linear range for the glucose detection are from 0.001 mM to 30 mM and limit of detection was found to be 0.0005 mM. The sensitivity was estimated around 77 mV/decade. The developed biosensor is highly selective, sensitive, stable and reproducible. The glucose biosensor was used for the determination of real human blood samples and the obtained results are satisfactory. The CuO material is functional therefore can be capitalized in wide range of applications such as lithium ion batteries, all oxide solar cells and supercapacitors.

  19. A new paradigm for constraining PM2.5 speciation by combining multiangular and polarimetric remote sensing with chemical transport model information

    Science.gov (United States)

    Kalashnikova, O.; Xu, F.; Ge, C.; Wang, J.; Garay, M. J.; Diner, D. J.

    2014-12-01

    Exposure to ambient particulate matter (PM) has been consistently linked to cardiovascular and respiratory health effects. Although PM is currently monitored by a network of surface stations, these are too sparsely distributed to provide the level of spatial detail needed to link different aerosol species to given health effects, and expansion to denser coverage is impractical and cost prohibitive. We present a methodology for combining Chemical Transport Model (CTM) aerosol type information and multiangular spectropolarimetric data to establish the signature of specific aerosol types in top-of-atmosphere measurements, and relate it to speciated surface PM2.5 loadings. In particular, we employ the WRF-Chem model run at the University of Nebraska, and remote sensing data from the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) to explore the feasibility of this approach. We demonstrate that the CTM does well in predicting the types of aerosols present at a given location and time, however large uncertainties currently exist in CTM estimates of the concentration of the various aerosol species (e.g., black carbon, sulfate, dust, etc.) leading to large uncertainties to model-derived speciated PM 2.5. In order to constrain CTM aerosol surface concentrations we use AirMSPI UV-VIS-NIR observations of intensity, and blue, red, and NIR observations of the Q and U Stokes parameters. We select specific scenes observed by AirMSPI and use WRF-Chem to generate an initial distribution of aerosol composition. The relevant optical properties for each aerosol species are used to calculate aerosol light scattering information. This is then used in a vector (polarized) 1-D radiative transfer model to determine at-instrument Stokes parameters for the specific AirMSPI viewing geometries. As a first step, a match is sought between the CTM-predicted radiances and the AirMSPI observations. Then, the total aerosol optical depth and fractions of various aerosol species are modified

  20. Multitarget sensing of glucose and cholesterol based on Janus hydrogel microparticles.

    Science.gov (United States)

    Sun, Xiao-Ting; Zhang, Ying; Zheng, Dong-Hua; Yue, Shuai; Yang, Chun-Guang; Xu, Zhang-Run

    2017-06-15

    A visualized sensing method for glucose and cholesterol was developed based on the hemispheres of the same Janus hydrogel microparticles. Single-phase and Janus hydrogel microparticles were both generated using a centrifugal microfluidic chip. For glucose sensing, concanavalin A and fluorescein labeled dextran used for competitive binding assay were encapsulated in alginate microparticles, and the fluorescence of the microparticles was positively correlated with glucose concentration. For cholesterol sensing, the microparticles embedded with γ-Fe 2 O 3 nanoparticles were used as catalyst for the oxidation of 3,3',5,5'-Tetramethylbenzidine by H 2 O 2 , an enzymatic hydrolysis product of cholesterol. And the color transition was more sensitive in the microparticles than in solutions, indicating the microparticles are more applicable for visualized determination. Furthermore, Janus microparticles were employed for multitarget sensing in the two hemespheres, and glucose and cholesterol were detected within the same microparticles without obvious interference. Besides, the particles could be manipulated by an external magnetic field. The glucose and cholesterol levels were measured in human serum utilizing the microparticles, which confirmed the potential application of the microparticles in real sample detection. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Science data collection with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Woelders, Kim; Madsen, Søren Nørvang

    1996-01-01

    Discusses examples on the use of polarimetric SAR in a number of Earth science studies. The studies are presently being conducted by the Danish Center for Remote Sensing. A few studies of the European Space Agency's EMAC programme are also discussed. The Earth science objectives are presented......, and the potential of polarimetric SAR is discussed and illustrated with data collected by the Danish airborne EMISAR system during a number of experiments in 1994 and 1995. The presentation will include samples of data acquired for the different studies...

  2. Mesoporous Nickel Oxide (NiO) Nanopetals for Ultrasensitive Glucose Sensing

    Science.gov (United States)

    Mishra, Suryakant; Yogi, Priyanka; Sagdeo, P. R.; Kumar, Rajesh

    2018-01-01

    Glucose sensing properties of mesoporous well-aligned, dense nickel oxide (NiO) nanostructures (NSs) in nanopetals (NPs) shape grown hydrothermally on the FTO-coated glass substrate has been demonstrated. The structural study based investigations of NiO-NPs has been carried out by X-ray diffraction (XRD), electron and atomic force microscopies, energy dispersive X-ray (EDX), and X-ray photospectroscopy (XPS). Brunauer-Emmett-Teller (BET) measurements, employed for surface analysis, suggest NiO's suitability for surface activity based glucose sensing applications. The glucose sensor, which immobilized glucose on NiO-NPs@FTO electrode, shows detection of wide range of glucose concentrations with good linearity and high sensitivity of 3.9 μA/μM/cm2 at 0.5 V operating potential. Detection limit of as low as 1 μΜ and a fast response time of less than 1 s was observed. The glucose sensor electrode possesses good anti-interference ability, stability, repeatability & reproducibility and shows inert behavior toward ascorbic acid (AA), uric acid (UA) and dopamine acid (DA) making it a perfect non-enzymatic glucose sensor.

  3. Contact lenses for real-time colorimetric sensing of glucose

    OpenAIRE

    Bruen, Danielle; Albatal, Rami; Florea, Larisa; Diamond, Dermot

    2015-01-01

    Diabetes is a worldwide incurable disease1 known to have acute and chronic health affects2. This disease affects the cardiovascular and peripheral nervous systems, and the kidneys, also known to have fatal side affects1-3, including heart or kidney failure2. Monitoring physiological blood-glucose concentrations is a means of managing diabetes, however few monitoring methods currently exist1-3. ‘Finger-pricking’ is the most common method, although invasive and non-continuous. This method is in...

  4. Radially oriented nanostrand electrodes to boost glucose sensing in mammalian blood.

    Science.gov (United States)

    Akhtar, Naeem; El-Safty, Sherif A; Abdelsalam, Mamdouh E; Shenashen, Mohamed A; Kawarada, Hiroshi

    2016-03-15

    Architecture of nanoscale electrochemical sensors for ultra-trace detection of glucose in blood is important in real-life sampling and analysis. To broaden the application of electrochemical sensing of glucose, we fabricated, for the first time, a glucose sensor electrode based on radially oriented NiO nanostrands (NSTs) onto 3D porous Ni foam substrate for monitoring, as well as selective and sensitive sensing of glucose in mammalian blood. The simple, scalable one-pot fabrication of this NST-Ni sensor design enabled control of the pattern of radially oriented NSTs onto 3D porous Ni foam substrate. The radial orientation of NST-Ni electrode onto the interior of the 3D porous substrate with controlled crystal structure size and atomic arrangement along the axis of the strands, intrinsic surface defects, and superior surface properties, such as hydrophilicity, high surface energy, and high density led to highly exposed catalytic active sites. The hierarchical NST-Ni electrode was used to develop a sensitive and selective sensor over a wide range of glucose concentrations among actively competitive ions, chemical species and molecular agents, and multi-cyclic sensing assays. The NST-Ni electrode shows significant glucose sensing performance in terms of unimpeded diffusion pathways, a wide range of concentration detection, and lower limit of detection (0.186 µM) than NiO nanosheet (NS)-Ni foam electrode pattern, indicating the effectiveness of the shape-dependent structural architecture of NST-Ni electrode. In this study, the NST-Ni electrode is fabricated to develop a simple, selective method for detecting glucose in physiological fluids (e.g., mammalian blood). Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Potential Roles of GLUT12 for Glucose Sensing and Cellular Migration in MCF-7 Human Breast Cancer Cells Under High Glucose Conditions.

    Science.gov (United States)

    Matsui, Chihiro; Takatani-Nakase, Tomoka; Maeda, Sachie; Nakase, Ikuhiko; Takahashi, Koichi

    2017-12-01

    Recent reports have indicated that hyperglycaemia is associated with breast cancer progression. High glucose conditions corresponding to hyperglycaemia significantly promote migration of MCF-7 human breast cancer cells, however, little is known about the mechanisms of glucose sensing for the acquisition of migratory properties by MCF-7 cells. This study investigated glucose sensing and mediation, which are responsible for the high motility of MCF-7 cells. We evaluated the migration of MCF-7 cells cultured in high glucose-containing medium and essential regulatory factors from the perspective of the glucose transport system. We demonstrated that glucose transporter 12 (GLUT12) protein level increased in MCF-7 cells and co-localized with actin organization under high glucose conditions. Moreover, GLUT12-knockdown completely abrogated high glucose-induced migration, indicating that GLUT12 functionally participates in sensing high glucose concentrations. GLUT12 plays a critical role in the model of breast cancer progression through high glucose concentrations. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  6. Recurrent potential pulse technique for improvement of glucose sensing ability of 3D polypyrrole

    Science.gov (United States)

    Cysewska, Karolina; Karczewski, Jakub; Jasiński, Piotr

    2017-07-01

    In this work, a new approach for using a 3D polypyrrole (PPy) conducting polymer as a sensing material for glucose detection is proposed. Polypyrrole is electrochemically polymerized on a platinum screen-printed electrode in an aqueous solution of lithium perchlorate and pyrrole. PPy exhibits a high electroactive surface area and high electrochemical stability, which results in it having excellent electrocatalytic properties. The studies show that using the recurrent potential pulse technique results in an increase in PPy sensing stability, compared to the amperometric approach. This is due to the fact that the technique, under certain parameters, allows the PPy redox properties to be fully utilized, whilst preventing its anodic degradation. Because of this, the 3D PPy presented here has become a very good candidate as a sensing material for glucose detection, and can work without any additional dopants, mediators or enzymes.

  7. Non-Enzymatic Glucose Sensing Using Carbon Quantum Dots Decorated with Copper Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Houcem Maaoui

    2016-10-01

    Full Text Available Perturbations in glucose homeostasis is critical for human health, as hyperglycemia (defining diabetes leads to premature death caused by macrovascular and microvascular complications. However, the simple and accurate detection of glucose in the blood at low cost remains a challenging task, although it is of great importance for the diagnosis and therapy of diabetic patients. In this work, carbon quantum dots decorated with copper oxide nanostructures (CQDs/Cu2O are prepared by a simple hydrothermal approach, and their potential for electrochemical non-enzymatic glucose sensing is evaluated. The proposed sensor exhibits excellent electrocatalytic activity towards glucose oxidation in alkaline solutions. The glucose sensor is characterized by a wide concentration range from 6 µM to 6 mM, a sensitivity of 2.9 ± 0.2 µA·µM−1·cm−2, and a detection limit of 6 µM at a signal-to-noise ratio S/N = 3. The sensors are successfully applied for glucose determination in human serum samples, demonstrating that the CQDs/Cu2O-based glucose sensor satisfies the requirements of complex sample detection with adapted potential for therapeutic diagnostics.

  8. Transient Congenital Hypothyroidism Alters Gene Expression of Glucose Transporters and Impairs Glucose Sensing Apparatus in Young and Aged Offspring Rats

    Directory of Open Access Journals (Sweden)

    Hanieh Gholami

    2017-10-01

    Full Text Available Background/Aims: Transient congenital hypothyroidism (TCH could disturb carbohydrate metabolism in adulthood. Aging is associated with increased risk of type 2 diabetes. This study aims to address effects of TCH on mRNA expressions of glucose transporters (GLUTs and glucokinase (GcK in islets and insulin target tissues of aged offspring rats. Methods: The TCH group received water containing 0.025% 6-propyl-2-thiouracil during gestation. Offspring from control and TCH groups (n=6 in each group were followed until month 19. Gene expressions of GLUTs and GcK were measured at months 3 and 19. Results: Compared to controls, aged TCH rats had higher GLUT4 expression in heart (4.88 fold and soleus (6.91 fold, while expression was lower in epididymal fat (12%. In TCH rats, GLUT2 and GcK expressions in islets were lower in young (12% and 10%, respectively and higher in aged (10.85 and 8.42 fold, respectively rats. In addition, liver GLUT2 and GcK expressions were higher in young (13.11 and 21.15 fold, respectively and lower in aged rats (44% and 5%, respectively. Conclusion: Thyroid hormone deficiency during fetal period impaired glucose sensing apparatus and changed glucose transporter expression in insulin-sensitive tissues of aged offspring rats. These changes may contribute to impaired carbohydrate metabolism.

  9. Transient Congenital Hypothyroidism Alters Gene Expression of Glucose Transporters and Impairs Glucose Sensing Apparatus in Young and Aged Offspring Rats.

    Science.gov (United States)

    Gholami, Hanieh; Jeddi, Sajad; Zadeh-Vakili, Azita; Farrokhfall, Khadije; Rouhollah, Fatemeh; Zarkesh, Maryam; Ghanbari, Mahboubeh; Ghasemi, Asghar

    2017-01-01

    Transient congenital hypothyroidism (TCH) could disturb carbohydrate metabolism in adulthood. Aging is associated with increased risk of type 2 diabetes. This study aims to address effects of TCH on mRNA expressions of glucose transporters (GLUTs) and glucokinase (GcK) in islets and insulin target tissues of aged offspring rats. The TCH group received water containing 0.025% 6-propyl-2-thiouracil during gestation. Offspring from control and TCH groups (n=6 in each group) were followed until month 19. Gene expressions of GLUTs and GcK were measured at months 3 and 19. Compared to controls, aged TCH rats had higher GLUT4 expression in heart (4.88 fold) and soleus (6.91 fold), while expression was lower in epididymal fat (12%). In TCH rats, GLUT2 and GcK expressions in islets were lower in young (12% and 10%, respectively) and higher in aged (10.85 and 8.42 fold, respectively) rats. In addition, liver GLUT2 and GcK expressions were higher in young (13.11 and 21.15 fold, respectively) and lower in aged rats (44% and 5%, respectively). Thyroid hormone deficiency during fetal period impaired glucose sensing apparatus and changed glucose transporter expression in insulin-sensitive tissues of aged offspring rats. These changes may contribute to impaired carbohydrate metabolism. © 2017 The Author(s). Published by S. Karger AG, Basel.

  10. Hypoxia-Inducible Factor Directs POMC Gene to Mediate Hypothalamic Glucose Sensing and Energy Balance Regulation

    Science.gov (United States)

    Zhang, Hai; Zhang, Guo; Gonzalez, Frank J.; Park, Sung-min; Cai, Dongsheng

    2011-01-01

    Hypoxia-inducible factor (HIF) is a nuclear transcription factor that responds to environmental and pathological hypoxia to induce metabolic adaptation, vascular growth, and cell survival. Here we found that HIF subunits and HIF2α in particular were normally expressed in the mediobasal hypothalamus of mice. Hypothalamic HIF was up-regulated by glucose to mediate the feeding control of hypothalamic glucose sensing. Two underlying molecular pathways were identified, including suppression of PHDs by glucose metabolites to prevent HIF2α degradation and the recruitment of AMPK and mTOR/S6K to regulate HIF2α protein synthesis. HIF activation was found to directly control the transcription of POMC gene. Genetic approach was then employed to develop conditional knockout mice with HIF inhibition in POMC neurons, revealing that HIF loss-of-function in POMC neurons impaired hypothalamic glucose sensing and caused energy imbalance to promote obesity development. The metabolic effects of HIF in hypothalamic POMC neurons were independent of leptin signaling or pituitary ACTH pathway. Hypothalamic gene delivery of HIF counteracted overeating and obesity under conditions of nutritional excess. In conclusion, HIF controls hypothalamic POMC gene to direct the central nutrient sensing in regulation of energy and body weight balance. PMID:21814490

  11. Hypoxia-inducible factor directs POMC gene to mediate hypothalamic glucose sensing and energy balance regulation.

    Directory of Open Access Journals (Sweden)

    Hai Zhang

    2011-07-01

    Full Text Available Hypoxia-inducible factor (HIF is a nuclear transcription factor that responds to environmental and pathological hypoxia to induce metabolic adaptation, vascular growth, and cell survival. Here we found that HIF subunits and HIF2α in particular were normally expressed in the mediobasal hypothalamus of mice. Hypothalamic HIF was up-regulated by glucose to mediate the feeding control of hypothalamic glucose sensing. Two underlying molecular pathways were identified, including suppression of PHDs by glucose metabolites to prevent HIF2α degradation and the recruitment of AMPK and mTOR/S6K to regulate HIF2α protein synthesis. HIF activation was found to directly control the transcription of POMC gene. Genetic approach was then employed to develop conditional knockout mice with HIF inhibition in POMC neurons, revealing that HIF loss-of-function in POMC neurons impaired hypothalamic glucose sensing and caused energy imbalance to promote obesity development. The metabolic effects of HIF in hypothalamic POMC neurons were independent of leptin signaling or pituitary ACTH pathway. Hypothalamic gene delivery of HIF counteracted overeating and obesity under conditions of nutritional excess. In conclusion, HIF controls hypothalamic POMC gene to direct the central nutrient sensing in regulation of energy and body weight balance.

  12. Mathematical Modeling of Interacting Glucose-Sensing Mechanisms and Electrical Activity Underlying Glucagon-Like Peptide 1 Secretion.

    Directory of Open Access Journals (Sweden)

    Michela Riz

    2015-12-01

    Full Text Available Intestinal L-cells sense glucose and other nutrients, and in response release glucagon-like peptide 1 (GLP-1, peptide YY and other hormones with anti-diabetic and weight-reducing effects. The stimulus-secretion pathway in L-cells is still poorly understood, although it is known that GLP-1 secreting cells use sodium-glucose co-transporters (SGLT and ATP-sensitive K+-channels (K(ATP-channels to sense intestinal glucose levels. Electrical activity then transduces glucose sensing to Ca2+-stimulated exocytosis. This particular glucose-sensing arrangement with glucose triggering both a depolarizing SGLT current as well as leading to closure of the hyperpolarizing K(ATP current is of more general interest for our understanding of glucose-sensing cells. To dissect the interactions of these two glucose-sensing mechanisms, we build a mathematical model of electrical activity underlying GLP-1 secretion. Two sets of model parameters are presented: one set represents primary mouse colonic L-cells; the other set is based on data from the GLP-1 secreting GLUTag cell line. The model is then used to obtain insight into the differences in glucose-sensing between primary L-cells and GLUTag cells. Our results illuminate how the two glucose-sensing mechanisms interact, and suggest that the depolarizing effect of SGLT currents is modulated by K(ATP-channel activity. Based on our simulations, we propose that primary L-cells encode the glucose signal as changes in action potential amplitude, whereas GLUTag cells rely mainly on frequency modulation. The model should be useful for further basic, pharmacological and theoretical investigations of the cellular signals underlying endogenous GLP-1 and peptide YY release.

  13. Nonenzymatic glucose sensing based on deposited palladium nanoparticles on epoxy-silver electrodes

    International Nuclear Information System (INIS)

    Gutes, Albert; Carraro, Carlo; Maboudian, Roya

    2011-01-01

    Highlights: → New nonenzymatic glucose sensor material. → Modified epoxy-silver electrodes with palladium nanoparticles. → Simple electroless surface modification. → Wide linear response range. → Easy implementation. - Abstract: A new approach for nonenzymatic glucose sensing, based on a simple modification of epoxy-silver surfaces deposited on the tip of commercial copper electric wires, is presented. Palladium was galvanically displaced on the surface of the epoxy-silver surface in order to obtain metal nanoparticles that act as catalyst for the direct oxidation of glucose. Scanning electron microscopy revealed the formation of the metal nanoparticles. X-ray photoelectron spectroscopy confirmed the metallic nature of the formed nanostructures on the surface. Electrochemical characterization and calibration of the palladium-modified epoxy-silver electrode is reported, obtaining a linear range of 1-20 mM for the detection of glucose with low interference of ascorbic acid and uric acid. A simple 3-step coulometry was used as the detection technique. The developed sensing material is believed to be a great candidate for integration in small devices for clinical essays, due to the simplicity and cost effectiveness of the presented approach, compared to the state-of-the-art devices reported recently in the literature. Simplicity in the coulometry determinations makes these Pd-modified epoxy-silver sensors a good candidate for easy glucose determinations.

  14. Nonenzymatic glucose sensing based on deposited palladium nanoparticles on epoxy-silver electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Gutes, Albert, E-mail: agutes@gmail.com [Department of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States); Carraro, Carlo; Maboudian, Roya [Department of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, CA 94720 (United States)

    2011-07-01

    Highlights: > New nonenzymatic glucose sensor material. > Modified epoxy-silver electrodes with palladium nanoparticles. > Simple electroless surface modification. > Wide linear response range. > Easy implementation. - Abstract: A new approach for nonenzymatic glucose sensing, based on a simple modification of epoxy-silver surfaces deposited on the tip of commercial copper electric wires, is presented. Palladium was galvanically displaced on the surface of the epoxy-silver surface in order to obtain metal nanoparticles that act as catalyst for the direct oxidation of glucose. Scanning electron microscopy revealed the formation of the metal nanoparticles. X-ray photoelectron spectroscopy confirmed the metallic nature of the formed nanostructures on the surface. Electrochemical characterization and calibration of the palladium-modified epoxy-silver electrode is reported, obtaining a linear range of 1-20 mM for the detection of glucose with low interference of ascorbic acid and uric acid. A simple 3-step coulometry was used as the detection technique. The developed sensing material is believed to be a great candidate for integration in small devices for clinical essays, due to the simplicity and cost effectiveness of the presented approach, compared to the state-of-the-art devices reported recently in the literature. Simplicity in the coulometry determinations makes these Pd-modified epoxy-silver sensors a good candidate for easy glucose determinations.

  15. Nonenzymatic glucose sensing by CuO nanoparticles decorated nitrogen-doped graphene aerogel.

    Science.gov (United States)

    Yang, Jing; Tan, Wensheng; Chen, Chuanxiang; Tao, Yongxin; Qin, Yong; Kong, Yong

    2017-09-01

    CuO nanoparticles decorated N-doped graphene aerogel (NGA-CuO) was facilely synthesized via a mild hydrothermal method followed by freeze-drying and calcination, which was characterized by TEM, FT-IR, XPS, XRD and electrochemical impedance spectroscopy (EIS). The obtained NGA-CuO was used for the construction of a nonenzymatic sensing platform for glucose, exhibiting wide linear range, low detection limit, high sensitivity, reproducibility, selectivity and stability. The excellent analytical performances of the NGA-CuO based glucose sensor might be attributed to the synergistic effect of CuO nanoparticles and N-doped graphene aerogel (NGA). The practical applications of the proposed sensor was verified by determining glucose concentrations in five human serum samples, and the obtained results were quite comparable to those measured on the standard clinical instrument. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Development and Validation of a Polarimetric-MCScene 3D Atmospheric Radiation Model

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., Burlington, MA (United States); Hawes, Frederick [Spectral Sciences, Inc., Burlington, MA (United States); Fox, Marsha [Spectral Sciences, Inc., Burlington, MA (United States)

    2016-03-15

    measurement program in collaboration with the Remote Sensing and Exploitation group at Sandia National Laboratories (SNL) in which data from their ongoing polarimetric field and laboratory measurement program will be shared and, to the extent allowed, tailored for model validation in exchange for model predictions under conditions and for geometries outside of their measurement domain.

  17. Fast, Highly-Sensitive, and Wide-Dynamic-Range Interdigitated Capacitor Glucose Biosensor Using Solvatochromic Dye-Containing Sensing Membrane.

    Science.gov (United States)

    Khan, Md Rajibur Rahaman; Khalilian, Alireza; Kang, Shin-Won

    2016-02-20

    In this paper, we proposed an interdigitated capacitor (IDC)-based glucose biosensor to measure different concentrations of glucose from 1 μM to 1 M. We studied four different types of solvatochromic dyes: Auramine O, Nile red, Rhodamine B, and Reichardt's dye (R-dye). These dyes were individually incorporated into a polymer [polyvinyl chloride (PVC)] and N,N-Dimethylacetamide (DMAC) solution to make the respective dielectric/sensing materials. To the best of our knowledge, we report for the first time an IDC glucose biosensing system utilizing a solvatochromic-dye-containing sensing membrane. These four dielectric or sensing materials were individually placed into the interdigitated electrode (IDE) by spin coating to make four IDC glucose biosensing elements. The proposed IDC glucose biosensor has a high sensing ability over a wide dynamic range and its sensitivity was about 23.32 mV/decade. It also has fast response and recovery times of approximately 7 s and 5 s, respectively, excellent reproducibility with a standard deviation of approximately 0.023, highly stable sensing performance, and real-time monitoring capabilities. The proposed IDC glucose biosensor was compared with an IDC, potentiometric, FET, and fiber-optic glucose sensor with respect to response time, dynamic range width, sensitivity, and linearity. We observed that the designed IDC glucose biosensor offered excellent performance.

  18. Noninvasive glucose sensing in scattering media using OCT, PAS, and TOF techniques

    Science.gov (United States)

    Alarousu, Erkki; Hast, Jukka T.; Kinnunen, Matti T.; Kirillin, Mikhail Y.; Myllyla, Risto A.; Plucinski, Jerzy; Popov, Alexey P.; Priezzhev, Alexander V.; Prykari, Tuukka; Saarela, Juha; Zhao, Zuomin

    2004-08-01

    In this paper, optical measurement techniques, which enable non-invasive measurement, are superimposed to glucose sensing in scattering media. Used measurement techniques are Optical Coherence Tomography (OCT), Photoacoustic spectroscopy (PAS) and laser pulse Time-of-Flight (TOF) measurement using a streak camera. In parallel with measurements, a Monte-Carlo (MC) simulation models have been developed. Experimental in vitro measurements were performed using Intralipid fat emulsion as a tissue simulating phantom for OCT and TOF measurements. In PAS measurements, a pork meat was used as a subject but also preliminary in vivo measurements were done. OCT measurement results show that the slope of the OCT signal's envelope changes as a function of glucose content in the scattering media. TOF measurements show that the laser pulse full width of half maximum (FWHM) changes a little as function of glucose content. An agreement with MC-simulations and measurements with Intralipid was also found. Measurement results of PAS technique show that changes in glucose content in the pork meat tissue can be measured. In vivo measurements with a human volunteer show that other factors such as physiological change, blood circulation and body temperature drift may interfere the PA response of glucose.

  19. Blood plasma separation in ZnO nanoflowers-supported paper based microfluidic for glucose sensing

    Science.gov (United States)

    Muhimmah, Luthviyah Choirotul; Roekmono, Hadi, Harsono; Yuwono, Rio Akbar; Wahyuono, Ruri Agung

    2018-04-01

    Blood plasma separation is essential to analyze and quantify the bio-substances in the human blood and hence, allows for diagnosing various diseases. This paper presents the two layer paper-based microfluidic analytical devices coated with ZnO nanoflowers (ZnO NF-µPAD) for a rapid blood plasma separation and glucose sensing. Plasma separation in ZnO NF-µPAD was evaluated experimentally and numerically using computational fluid dynamics package for a flow over porous networks. Glucose detection was carried out using Fourier-transform infrared (FTIR) measurements. The glucose concentrations in the red blood samples investigated here vary in the range of 150 - 310 mg.dl-1. The plasma separation process on ZnO NF-μPAD requires 240 ± 93 s. The spectroscopic data reveals that the IR absorptions and Raman signals at the typical vibrational frequencies of glucose are increasing at higher glucose concentration. After subtraction from absorption background arising from ZnO NF and the paper, linearly increasing IR absorption (913 and 1349 cm-1) and Raman signals (1346 and 1461 cm-1) are observable with a relatively good sensitivity.

  20. Composite Hydrogels with Engineered Microdomains for Optical Glucose Sensing at Low Oxygen Conditions

    Directory of Open Access Journals (Sweden)

    Lindsey R. Bornhoeft

    2017-01-01

    Full Text Available There is a growing need for advanced tools that enable frequent monitoring of biomarkers for precision medicine. In this work, we present a composite hydrogel-based system providing real-time optical bioanalyte monitoring. The responsive material, alginate-in-alginate (AnA, is comprised of an alginate hydrogel with embedded bioactive, nanofilm-coated phosphorescent microdomains; palladium tetracarboxyphenylporphyrin serves as an optical indicator, glucose oxidase as a model enzyme, and layer-by-layer deposited polyelectrolyte multilayers (PEMs as the diffusion barrier. Glutaraldehyde crosslinking of the nanofilms resulted in a dramatic reduction in glucose diffusion (179% while oxygen transport was not significantly affected. The responses of the AnA hydrogels to step changes of glucose at both ambient and physiological oxygen levels were evaluated, revealing controlled tuning of sensitivity and dynamic range. Stability, assessed by alternately exposing the responsive AnA hydrogels to extremely high and zero glucose concentrations, resulted in no significant difference in the response over 20 cycles. These AnA hydrogels represent an attractive approach to biosensing based on biocompatible materials that may be used as minimally-invasive, implantable devices capable of optical interrogation. The model glucose-responsive composite material studied in this work will serve as a template that can be translated for sensing additional analytes (e.g., lactate, urea, pyruvate, cholesterol and can be used for monitoring other chronic conditions.

  1. The GNSS polarimetric radio-occultation technique to sense precipitation events: a new concept to be tested aboard PAZ Low Earth Satellite

    Science.gov (United States)

    Tomás, Sergio; Oliveras, Santi; Cardellach, Estel; Rius, Antonio

    2013-04-01

    The Radio Occultation and Heavy Precipitation (ROHP) experiment, to be conducted aboard the Spanish PAZ satellite, consists of a radio occultation (RO) mission provided with dual-polarization capabilities. The research with polarimetric RO data has the goal of assessing the capabilities and limitations of this technique to infer profiles of heavy precipitation. The technique aims to provide vertical profiles of precipitation simultaneously to the vertical profiles of thermodynamic parameters (standard RO products) perfectly collocated both in space and time. If successful, the polarimetric RO will represent the first technique able to provide these complementary information on precipitation. This is a relevant input for studies on heavy and violent rainfall events, which being poorly represented by the current-generation of Numerical Weather Prediction and General Circulation Models appear to be difficult to forecast on all time-scales. The Low Earth Orbiter hosting this experiment, to be launched in 2013, will orbit at 500 km altitude in a near-Polar orbit. The Radio Occulation payload includes a RO GNSS receiver and a dual polarization (H/V) limb oriented antenna to capture the signals of setting GNSS transmitters. NOAA and UCAR participate in the ground-segment of the radiometric experiment to enable near-real time dissemination of the level-1 standard RO products. The space-based GNSS RO technique scans the atmosphere vertically at fine resolution (close to 300 meter in the troposphere) by precisely measure the delay between a GNSS transmitter and a GNSS receiver aboard a Low Earth Orbiter, when the former is setting below or rising above the Earth limb. The standard, thermodynamical, products are extracted from the excess delay induced by the atmosphere at different layers. This presentation will not focus on this well-established application, but a novel concept using polarimetry to also retrieve rain information. The precipitation-measurement principle is

  2. Alteration of hypothalamic glucose and lactate sensing in 48h hyperglycemic rats.

    Science.gov (United States)

    Allard, Camille; Carneiro, Lionel; Collins, Stephan C; Chrétien, Chloé; Grall, Sylvie; Pénicaud, Luc; Leloup, Corinne

    2013-02-08

    Hypothalamic detection of nutrients is involved in the control of energy metabolism and is altered in metabolic disorders. Although hypothalamic detection of blood lactate lowers hepatic glucose production and food intake, it is unknown whether it also modulates insulin secretion. To address this, a lactate injection via the right carotid artery (cephalad) was performed in Wistar rats. This triggered a transient increase in insulin secretion. Rats made hyperglycemic for 48h exhibited prolonged insulin secretion in response to a glucose injection via the carotid artery, but lactate injection induced two types of responses: half of the HG rats showed no difference compared to controls and the other half had markedly decreased insulin secretion. Astroglial monocarboxylates transporters MCT1 and MCT4 isoforms transfer lactate from blood to astrocytes and release lactate to the extracellular space, whilst the neuronal MCT2 isoform permits neuronal lactate uptake. We found that astroglial MCT1 and MCT4, and neuronal MCT2 protein levels in the medio-basal hypothalamus (MBH) were not modified by 48h-hyperglycemia. Together, these results indicate that hypothalamic sensing of circulating lactate triggers insulin secretion. Both glucose and lactate sensing are altered in a model of hyperglycemia, without alteration of MBH MCTs protein levels. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  3. Archetypal sandwich-structured CuO for high performance non-enzymatic sensing of glucose

    Science.gov (United States)

    Meher, Sumanta Kumar; Rao, G. Ranga

    2013-02-01

    In the quest to enhance the selectivity and sensitivity of novel structured metal oxides for electrochemical non-enzymatic sensing of glucose, we report here a green synthesis of unique sandwich-structured CuO on a large scale under microwave mediated homogeneous precipitation conditions. The physicochemical studies carried out by XRD and BET methods show that the monoclinic CuO formed via thermal decomposition of Cu2(OH)2CO3 possesses monomodal channel-type pores with largely improved surface area (~43 m2 g-1) and pore volume (0.163 cm3 g-1). The fascinating surface morphology and pore structure of CuO is formulated due to homogeneous crystallization and microwave induced self assembly during synthesis. The cyclic voltammetry and chronoamperometry studies show diffusion controlled glucose oxidation at ~0.6 V (vs. Ag/AgCl) with extremely high sensitivity of 5342.8 μA mM-1 cm-2 and respective detection limit and response time of ~1 μM and ~0.7 s, under a wide dynamic concentration range of glucose. The chronoamperometry measurements demonstrate that the sensitivity of CuO to glucose is unaffected by the absence of dissolved oxygen and presence of poisoning chloride ions in the reaction medium, which essentially implies high poison resistance activity of the sandwich-structured CuO. The sandwich-structured CuO also shows insignificant interference/significant selectivity to glucose, even in the presence of high concentrations of other sugars as well as reducing species. In addition, the sandwich-structured CuO shows excellent reproducibility (relative standard deviation of ~2.4% over ten identically fabricated electrodes) and outstanding long term stability (only ~1.3% loss in sensitivity over a period of one month) during non-enzymatic electrochemical sensing of glucose. The unique microstructure and suitable channel-type pore architecture provide structural stability and maximum accessible electroactive surface for unimpeded mobility of glucose as well as the

  4. Flexible electronics-compatible non-enzymatic glucose sensing via transparent CuO nanowire networks on PET films

    Science.gov (United States)

    Bell, Caroline; Nammari, Abdullah; Uttamchandani, Pranay; Rai, Amit; Shah, Pujan; Moore, Arden L.

    2017-06-01

    Diabetic individuals need simple, accurate, and cost effective means by which to independently assess their glucose levels in a non-invasive way. In this work, a sensor based on randomly oriented CuO nanowire networks supported by a polyethylene terephthalate thin film is evaluated as a flexible, transparent, non-enzymatic glucose sensing system analogous to those envisioned for future wearable diagnostic devices. The amperometric sensing characteristics of this type of device architecture are evaluated both before and after bending, with the system’s glucose response, sensitivity, lower limit of detection, and effect of applied bias being experimentally determined. The obtained data shows that the sensor is capable of measuring changes in glucose levels within a physiologically relevant range (0-12 mM glucose) and at lower limits of detection (0.05 mM glucose at +0.6 V bias) consistent with patient tears and saliva. Unlike existing studies utilizing a conductive backing layer or macroscopic electrode setup, this sensor demonstrates a percolation network-like trend of current versus glucose concentration. In this implementation, controlling the architectural details of the CuO nanowire network could conceivably allow the sensor’s sensitivity and optimal sensing range to be tuned. Overall, this work shows that integrating CuO nanowires into a sensor architecture compatible with transparent, flexible electronics is a promising avenue to realizing next generation wearable non-enzymatic glucose diagnostic devices.

  5. Polarimetric neutron scattering

    International Nuclear Information System (INIS)

    Tasset, F.

    2001-01-01

    Polarimetric Neutron Scattering in introduced, both by, explaining methodological issues and the corresponding instrumental developments. After a short overview of neutron spin polarization and the neutron polarization 3d-vector a pictorial approach of the microscopic theory is used to show how a polarized beam interacts with lattice and magnetic Fourier components in a crystal. Examples are given of using Spherical Neutron Polarimetry (SNP) and the corresponding Cryopad polarimeter for the investigation of non-collinear magnetic structures. (R.P.)

  6. Cu₂O-Au nanocomposites for enzyme-free glucose sensing with enhanced performances.

    Science.gov (United States)

    Hu, Qiyan; Wang, Fenyun; Fang, Zhen; Liu, Xiaowang

    2012-06-15

    A facile method for the synthesis of Cu(2)O-Au nanocomposites has been reported by injecting Cu(2)O nanocubes into Au precursor directly with the assistance of ultrasound radiation at room temperature. The ultrasound radiation is not a necessary requirement but can make the distribution of Au nanoparticles more homogenous. The formation of Cu(2)O-Au nanocomposites is attributed to following two reasons. The first one is the difference in the reduction potential between Cu(2+)/Cu(2)O and AuCl(4)(-)/Au, which can also be considered as the driving force for the redox reaction. The other one is the low lattice mismatch between (200) planes of Cu(2)O and (200) facets of Au, which is favorable for the formation of heterostructure. The electrochemical investigation demonstrates that the performances of Cu(2)O nanocubes in enzyme-free glucose sensing have been improved significantly after the decoration of Au nanoparticles which may be derived from the polarization effect provided by Au nanoparticles. As-prepared Cu(2)O-Au nanocomposites have great potential in enzyme-free glucose sensing. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Polarimetric imagery collection experiment

    Science.gov (United States)

    Romano, Joao M.; Felton, Melvin; Chenault, David; Sohr, Brian

    2010-04-01

    The Spectral and Polarimetric Imagery Collection Experiment (SPICE) is a collaborative effort between the US Army ARDEC and ARL that is focused on the collection of mid-wave and long-wave infrared imagery using hyperspectral, polarimetric, and broadband sensors. The objective of the program is to collect a comprehensive database of the different modalities over the course of 1 to 2 years to capture sensor performance over a wide variety of weather conditions, diurnal, and seasonal changes inherent to Picatinny's northern New Jersey location. Using the Precision Armament Laboratory (PAL) tower at Picatinny Arsenal, the sensors will autonomously collect the desired data around the clock at different ranges where surrogate 2S3 Self-Propelled Howitzer targets are positioned at different viewing perspectives in an open field. The database will allow for: 1) Understanding of signature variability under adverse weather conditions; 2) Development of robust algorithms; 3) Development of new sensors; 4) Evaluation of polarimetric technology; and 5) Evaluation of fusing the different sensor modalities. In this paper, we will present the SPICE data collection objectives, the ongoing effort, the sensors that are currently deployed, and how this work will assist researches on the development and evaluation of sensors, algorithms, and fusion applications.

  8. Studies on electrochemical glucose sensing, antimicrobial activity and cytotoxicity of fabricated copper nanoparticle immobilized chitin nanostructure.

    Science.gov (United States)

    Solairaj, Dhanasekaran; Rameshthangam, Palanivel; Muthukumaran, Palanisamy; Wilson, Jeyaraj

    2017-08-01

    In this study, copper nanoparticle immobilized chitin nanocomposite (CNP/CuNP) was synthesized and used for the development of non-enzymatic electrochemical sensor. The CNP/CuNP was characterized by X-ray diffraction (XRD), fourier transform infra red (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM) analysis. The glucose sensing property of CNP/CuNP was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). As a result of the synergistic effect of CNP and CuNP, the modified electrode displayed effective electro-oxidation of glucose in 0.1M NaOH solution. At 0.45V potential the modified electrode showed response towards glucose in the linear range of 1-1000μM with a lowest detection limit of 0.776μM with better selectivity and stability. In addition, the antimicrobial activity of CNP/CuNP was evaluated against bacterial and fungal strains. CNP/CuNP displayed enhanced antimicrobial activity when compared to CNP and CuNP alone. Similarly, cytotoxicity of CNP/CuNP was tested against Artemia salina, which showed no toxic effect in the tested concentration. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Pulse Laser Deposition Fabricating Gold Nanoclusters on a Glassy Carbon Surface for Nonenzymatic Glucose Sensing.

    Science.gov (United States)

    Shu, Honghui; Chang, Gang; Wang, Zhiqiang; Li, Pai; Zhang, Yuting; He, Yunbin

    2015-01-01

    A One-step technique for depositing gold nanoclusters (GNCs) onto the surface of a glassy carbon (GC) plate was developed by using pulse laser deposition (PLD) with appropriate process parameters. The method is simple and clean without using any templates, surfactants, or stabilizers. The experimental factors (pulse laser number and the pressure of inert gas (Ar)) that affect the morphology and structure of GNCs, and thus affect the electrocatalytic oxidation performance towards glucose were systematically investigated by means of transmission electron microscopy (TEM) and electrochemical methods (cyclic voltammograms (CV) and chronoamperometry methods). The GC electrode modified by GNCs exhibited a rapid response time (about 2 s), a broad linear range (0.1 to 20 mM), and good stability. The sensitivity was estimated to be 31.18 μA cm(-2) mM(-1) (vs. geometric area), which is higher than that of the Au bulk electrode. It has a good resistance to the common interfering species, such as ascorbic acid (AA), uric acid (UA) and 4-acetaminophen (AP). Therefore, this work has demonstrated a simple and effective sensing platform for the nonenzymatic detection of glucose, and can be used as a new material for a novel non-enzymatic glucose sensor.

  10. The Development of Polarimetric and Nonpolarimetric Multiwavelength Focal Plane Arrays, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance polarimetric and nonpolarimetric sensing is crucial to upcoming NASA missions, including ACE and CLARREO and the multi-agency VIIRS NPP project. The...

  11. Polarimetric Multiwavelength Focal Plane Arrays for ACE and CLARREO, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — High-performance polarimetric and nonpolarimetric sensing is crucial to upcoming NASA missions, including ACE and CLARREO and the multi-agency VIIRS NPP project. The...

  12. On-chip highly sensitive saliva glucose sensing using multilayer films composed of single-walled carbon nanotubes, gold nanoparticles, and glucose oxidase

    Directory of Open Access Journals (Sweden)

    Wenjun Zhang

    2015-06-01

    Full Text Available It is very important for human health to rapidly and accurately detect glucose levels in biological environments, especially for diabetes mellitus. We proposed a simple, highly sensitive, accurate, convenient, low-cost, and disposable glucose biosensor on a single chip. A working (sensor electrode, a counter electrode, and a reference electrode are integrated on a single chip through micro-fabrication. The working electrode is functionalized through a layer-by-layer (LBL assembly of single-walled carbon nanotubes (SWNTs and multilayer films composed of chitosan (CS, gold nanoparticles (GNp, and glucose oxidase (GOx to obtain high sensitivity and accuracy. The glucose sensor has following features: (1 direct electron transfer between GOx and the electrode surface; (2 on-a-chip; (3 glucose detection down to 0.1 mg/dL (5.6 μM; (4 good sensing linearity over 0.017–0.81 mM; (5 high sensitivity (61.4 μA/mM-cm2 with a small reactive area (8 mm2; (6 fast response; (7 high reproducibility and repeatability; (8 reliable and accurate saliva glucose detection. Thus, this disposable biosensor will be an alternative for real time tracking of glucose levels from body fluids, e.g. saliva, in a noninvasive, pain-free, accurate, and continuous way. In addition to being used as a disposable glucose biosensor, it also provides a suitable platform for on-chip electrochemical sensing for other chemical agents and biomolecules.

  13. Pulse electrodeposited nickel-indium tin oxide nanocomposite as an electrocatalyst for non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sivasakthi, P.; Ramesh Bapu, G.N.K., E-mail: rameshbapugnk@cecri.res.in; Chandrasekaran, Maruthai

    2016-01-01

    Nickel and nickel-ITO nanocomposite on mild steel substrate were prepared by pulse electrodeposition method from nickel sulphamate electrolyte and were examined as electrocatalysts for non-enzymatic glucose sensing. The surface morphology, chemical composition, preferred orientation and oxidation states of the nickel metal ion in the deposits were characterized by SEM, EDAX, XRD and XPS. Electrochemical sensing of glucose was studied by cyclic voltammetry and amperometry. The modified Ni-ITO nanocomposite electrode showed higher electrocatalytic activity for the oxidation of glucose in alkaline medium and exhibited a linear range from 0.02 to 3.00 mM with a limit of detection 3.74 μM at a signal-to-noise ratio of 3. The higher selectivity, longer stability and better reproducibility of this electrode compared to nickel in the sensing of glucose are pointers for exploitation in practical clinical applications. - Highlights: • Ni-ITO nanocomposites are prepared by pulse electrocodeposition method from nickel sulphamate solutions. • Ni-ITO nanocomposites are characterized using SEM, EDAX, XRD and XPS. • Electrochemical characteristics of the Ni and Ni-ITO nanocomposite deposits are studied by CV and amperometry techniques. • Ni-ITO nanocomposite electrode could be used as sensing material for detection of glucose in practical condition.

  14. Temperature-driven growth of reduced graphene oxide/copper nanocomposites for glucose sensing

    Science.gov (United States)

    Zhang, Qi; Wu, Zhong; Xu, Chen; Liu, Lei; Hu, Wenbin

    2016-12-01

    A one-spot method was developed for the synthesis of graphene sheet decorated with copper nanoparticles using different reduction temperatures via a molecular level mixing process. Here, we demonstrate that the reduction temperature is a crucial determinant of the properties of reduced graphene oxide (RGO)/metal composite and its electrocatalytic application in glucose sensing. To show this, we prepared a series of RGO/Cu composites at different reduction temperatures and examined the change rules of size, loading and dispersion of Cu particles, and the reduction extent of the RGO. Results showed that the Cu particle size increased with increasing reduction temperatures due to the Ostwald ripening process. Meanwhile, the Cu loading decreased with increasing reduction temperatures and the aggregation had not appeared in the high Cu loading situation. Additionally, the increasing reduction temperatures led to the decreasing concentrations of various oxygen-containing functional group of RGO with various degrees. The cyclic voltammogram showed that the RGO/metal composites fabricated under lower reduction temperatures exhibited higher electrocatalytic activity for glucose sensing, which was attributed to the higher surface area from larger loading of RGO/metal composites with smaller particle size. It can be concluded that the above factors play more significant roles in electrocatalytic efficiency than the decreased electron transfer rate between RGO and Cu within a certain range. These results highlight the importance of the reduction temperature influencing the properties of the RGO/metal composite and its application. We believe that these findings can be of great value in the further developing RGO/metal-based sensors for electrochemical detection of different analytes in emerging fields.

  15. Bisphenol A impairs hepatic glucose sensing in C57BL/6 male mice.

    Directory of Open Access Journals (Sweden)

    Leigh Perreault

    Full Text Available AIMS/HYPOTHESIS: Glucose sensing (eg. glucokinase activity becomes impaired in the development of type 2 diabetes, the etiology of which is unclear. Estrogen can stimulate glucokinase activity, whereas the pervasive environmental pollutant bisphenol A (BPA can inhibit estrogen action, hence we aimed to determine the effect of BPA on glucokinase activity directly. METHODS: To evaluate a potential acute effect on hepatic glucokinase activity, BPA in water (n = 5 vs. water alone (n = 5 was administered at the EPA's purported "safe dose" (50 µg/kg by gavage to lean 6-month old male C57BL/6 mice. Two hours later, animals were euthanized and hepatic glucokinase activity measured over glucose levels from 1-20 mmol/l in liver homogenate. To determine the effect of chronic BPA exposure on hepatic glucokinase activity, lean 6-month old male C57BL/6 mice were provided with water (n = 15 or water with 1.75 mM BPA (∼50 µg/kg/day; n = 14 for 2 weeks. Following the 2-week exposure, animals were euthanized and glucokinase activity measured as above. RESULTS: Hepatic glucokinase activity was signficantly suppressed after 2 hours in animals given an oral BPA bolus compared to those who received only water (p = 0.002-0.029 at glucose 5-20 mmol/l; overall treatment effect p<0.001. Exposure to BPA over 2 weeks also suppressed hepatic glucokinase activity in exposed vs. unexposed mice (overall treatment effect, p = 0.003. In both experiments, the Hill coefficient was higher and Vmax lower in mice treated with BPA. CONCLUSIONS/INTERPRETATION: Both acute and chronic exposure to BPA significantly impair hepatic glucokinase activity and function. These findings identify a potential mechanism for how BPA may increase risk for diabetes.

  16. Observations on the polarimetric imagery collection experiment database

    Science.gov (United States)

    Woolley, Mark; Michalson, Jacob; Romano, Joao

    2011-10-01

    The Spectral and Polarimetric Imagery Collection Experiment (SPICE) is an ongoing collaborative effort that commenced in February 2010 between the US Army ARDEC and Army Research Laboratory (ARL). SPICE is focused on the collection of mid-wave and long-wave infrared imagery using hyperspectral, polarimetric, and broadband sensors. The overall objective of SPICE is to collect a comprehensive database of the different modalities spanning multiple years to capture sensor performance encompassing a wide variety of meteorological (MET) conditions, diurnal, and seasonal changes inherent to Picatinny's northern New Jersey location. Utilizing the Precision Armament Laboratory (PAL) tower at Picatinny Arsenal, the sensors are autonomously collecting the desired data around the clock at multiple ranges containing surrogate 2S3 Self-Propelled Howitzer targets positioned at different orientations in an open woodland field. This database allows for: 1) Understanding of signature variability under adverse weather conditions; 2) Development of robust algorithms; 3) Development of new sensors; 4) Evaluation of polarimetric technology; and 5) Evaluation of fusing the different sensor modalities. In this paper, we will revisit the SPICE data collection objectives and the sensors deployed. We will present, in a statistical sense, the integrity of the data in the long-wave infrared (LWIR) polarimetric database collected from February through September 2010 and issues and lessons learned associated with a fully autonomous, around the clock data collection. We will also demonstrate sample LWIR polarimetric imagery and the performance of the Stokes parameters under adverse weather conditions.

  17. Polarimetric Scattering Properties of Landslides in Forested Areas and the Dependence on the Local Incidence Angle

    Directory of Open Access Journals (Sweden)

    Takashi Shibayama

    2015-11-01

    Full Text Available This paper addresses the local incidence angle dependence of several polarimetric indices corresponding to landslides in forested areas. Landslide is deeply related to the loss of human lives and their property. Various kinds of remote sensing techniques, including aerial photography, high-resolution optical satellite imagery, LiDAR and SAR interferometry (InSAR, have been available for landslide investigations. SAR polarimetry is potentially an effective measure to investigate landslides because fully-polarimetric SAR (PolSAR data contain more information compared to conventional single- or dual-polarization SAR data. However, research on landslide recognition utilizing polarimetric SAR (PolSAR is quite limited. Polarimetric properties of landslides have not been examined quantitatively so far. Accordingly, we examined the polarimetric scattering properties of landslides by an assessment of how the decomposed scattering power components and the polarimetric correlation coefficient change with the local incidence angle. In the assessment, PolSAR data acquired from different directions with both spaceborne and airborne SARs were utilized. It was found that the surface scattering power and the polarimetric correlation coefficient of landslides significantly decrease with the local incidence angle, while these indices of surrounding forest do not. This fact leads to establishing a method of effective detection of landslide area by polarimetric information.

  18. CuO nanoparticles supported on nitrogen and sulfur co-doped graphene nanocomposites for non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meixia [Hebei University of Engineering, Faculty of Material Science and Engineering (China); Guo, Qingbin, E-mail: guoqingbinhue@163.com [Hebei University of Engineering, Academic Affairs office (China); Xie, Juan; Li, Yongde; Feng, Yapeng [Hebei University of Engineering, Faculty of Material Science and Engineering (China)

    2017-01-15

    Developing highly active catalysts to promote the electrocatalytic glucose oxidation (EGO) is a crucial demand for non-enzymatic glucose sensing. Herein, we reported the use of nitrogen and sulfur co-doped graphene (NSG) as a novel support material for anchoring CuO nanoparticles and obtained CuO/NSG was employed as an efficient EGO catalyst for non-enzymatic glucose sensing. The results showed that the NSG endowed the CuO/NSG with large surface area, increased structural defects, improved conductivity, and strong covalent coupling between NSG and CuO. Owing to the significant contribution of NSG and the synergistic effect of NSG and CuO, the CuO/NSG exhibited a remarkably higher EGO activity than CuO and CuO/reduced graphene oxide. The CuO/NSG-based sensor displayed excellent glucose sensing performances with a considerably low detection limit of 0.07 μM. These findings elucidate that the NSG is a promising support material for non-enzymatic glucose detection.

  19. Synthesis of Three Dimensional Nickel Cobalt Oxide Nanoneedles on Nickel Foam, Their Characterization and Glucose Sensing Application

    Science.gov (United States)

    Hussain, Mushtaque; Ibupoto, Zafar Hussain; Abbasi, Mazhar Ali; Liu, Xianjie; Nur, Omer; Willander, Magnus

    2014-01-01

    In the present work, NiCo2O4 nanostructures are fabricated in three dimensions (3D) on nickel foam by the hydrothermal method. The nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The nanostructures exhibit nanoneedle-like morphology grown in 3D with good crystalline quality. The nanomaterial is composed of nickel, cobalt and oxygen atoms. By using the favorable porosity of the nanomaterial and the substrate itself, a sensitive glucose sensor is proposed by immobilizing glucose oxidase. The presented glucose sensor has shown linear response over a wide range of glucose concentrations from 0.005 mM to 15 mM with a sensitivity of 91.34 mV/decade and a fast response time of less than 10 s. The NiCo2O4 nanostructures-based glucose sensor has shown excellent reproducibility, repeatability and stability. The sensor showed negligible response to the normal concentrations of common interferents with glucose sensing, including uric acid, dopamine and ascorbic acid. All these favorable advantages of the fabricated glucose sensor suggest that it may have high potential for the determination of glucose in biological samples, food and other related areas. PMID:24647124

  20. Synthesis of Three Dimensional Nickel Cobalt Oxide Nanoneedles on Nickel Foam, Their Characterization and Glucose Sensing Application

    Directory of Open Access Journals (Sweden)

    Mushtaque Hussain

    2014-03-01

    Full Text Available In the present work, NiCo2O4 nanostructures are fabricated in three dimensions (3D on nickel foam by the hydrothermal method. The nanomaterial was characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS. The nanostructures exhibit nanoneedle-like morphology grown in 3D with good crystalline quality. The nanomaterial is composed of nickel, cobalt and oxygen atoms. By using the favorable porosity of the nanomaterial and the substrate itself, a sensitive glucose sensor is proposed by immobilizing glucose oxidase. The presented glucose sensor has shown linear response over a wide range of glucose concentrations from 0.005 mM to 15 mM with a sensitivity of 91.34 mV/decade and a fast response time of less than 10 s. The NiCo2O4 nanostructures-based glucose sensor has shown excellent reproducibility, repeatability and stability. The sensor showed negligible response to the normal concentrations of common interferents with glucose sensing, including uric acid, dopamine and ascorbic acid. All these favorable advantages of the fabricated glucose sensor suggest that it may have high potential for the determination of glucose in biological samples, food and other related areas.

  1. Performance and acceptability of a combined device for insulin infusion and glucose sensing in the home setting

    DEFF Research Database (Denmark)

    Nørgaard, K.; Shin, J.; Welsh, J. B.

    2015-01-01

    The use of sensor-augmented insulin pump (SAP) therapy is increasing. Currently, glucose sensors and insulin infusion cannulas are inserted separately. A new device, MiniMed Duo, combines sensing and infusion capabilities on the same platform and is intended to simplify device insertion and site...... connected to insulin pumps over 15 days (3 days/device) and test capillary blood glucose (SMBG) 7 times/day. The primary endpoint was the percentage of sensor-SMBG paired values within 20% of one another. Subject experiences were assessed via questionnaires. Overall, 74.8% of sensor-SMBG paired values were...... management. We evaluated the device's performance with respect to insulin delivery and glucose sensing, and its acceptability with patients. Forty-five patients (mean +/- SD age, 45.5 +/- 10.9 years, 48% female) with type 1 diabetes and previous use of SAP participated. Each subject was to wear 5 devices...

  2. Non-enzymatic glucose sensing properties of MoO3 nanorods: experimental and density functional theory investigations

    Science.gov (United States)

    Sharma, Maneesha; Gangan, Abhijeet; Chakraborty, Brahmananda; Sekhar Rout, Chandra

    2017-11-01

    We report the growth of monoclinic MoO3 nanorods by a simple and highly reproducible hydrothermal method. Structural and morphological studies provide significant insights about the phase and crystalline structure of the synthesized samples. Further, the non-enzymatic glucose sensing properties were investigated and the MoO3 nanorods exhibited a sensitivity of 15.4 µA µM‑1 cm‑2 in the 5–175 µM linear range. Also, a quick response time of 8 s towards glucose molecules was observed, exhibiting an excellent electrochemical activity. We have also performed density functional theory (DFT) simulations to qualitatively support our experimental observations by investigating the interactions and charge-transfer mechanism of glucose on MoO3. There is a strong interaction between glucose and the MoO3 surface due to charge transfer from a bonded O atom of glucose to a Mo atom of MoO3 resulting in a strong hybridization between the p orbital of O and d orbital of Mo. Thus, the MoO3 nanorod-based electrodes are found to be good glucose sensing materials for practical industrial applications.

  3. Synthesis of tremella-like CoS and its application in sensing of hydrogen peroxide and glucose.

    Science.gov (United States)

    Wu, Wenqin; Yu, Beibei; Wu, Huimin; Wang, Shengfu; Xia, Qinghua; Ding, Yu

    2017-01-01

    Different phases of cobalt sulfides have been fabricated by one-pot hydrothermal method. Comparing all of the prepared materials, and the results revealed that CoS was the most conductive and could accelerate electron transfer. The CoS presented tremella-like and excellent catalytic activities towards hydrogen peroxide and glucose. The sensor based on CoS performed amperometric sensing of hydrogen peroxide in a linear range between 5.00μM and 14.82mM. Meanwhile, sensing of glucose with double-linear range, one is between 5.00μM and 1.10mM, the other is between 1.20mM and 10.20mM. These due to the fact that more and more intermediate species absorb onto electrode surface with increasing the concentration of glucose, which limit the following glucose oxidation. Furthermore, the hydrogen peroxide and glucose sensors based on tremella-like CoS also exhibited excellent selectivity, stability, and reproducibility. Thus, the sensor showed potential utilities in hydrogen peroxide and glucose detection. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Symmetry of the Matrix Model of Anisotropic Media with Orthogonal Eigenmodes and its Application for the Developing of Remote Sensing Polarimetric Measurement Systems in Visible

    Science.gov (United States)

    2011-10-01

    with a quite high speed and accuracy without mechanical moving. Disadvantages of electrically controlled polarization transducers are: 1) nonlinear...www.meadowlark.com), the switching speed is symmetric and approximately 150 microseconds. Fig.1. Meadowlark’s Liquid Crystal Variable Retarder (LCVR...15. Tyo J.S., Goldstein D.L., Chenault D.B., and Shaw J.A. Review of passive imaging polarimetry for remote sensing applications // Appl. Opt

  5. Extensibility effect of poly(3-hexylthiophene) on the glucose sensing performance of mixed poly(3-hexylthiophene)/octadecylamine/glucose oxidase Langmuir-Blodgett films.

    Science.gov (United States)

    Wang, Ke-Hsuan; Hsu, Wen-Ping; Chen, Liang-Huei; Lin, Wei-Don; Lee, Yuh-Lang

    2017-07-01

    Poly(3-hexylthiophene) (P3HT) is utilized as a material to enhance the glucose sensing performance of glucose oxidase (GOx) Langmuir-Blodgett (LB) films. To enhance the extensibility and homogeneity of the P3HT in the LB films, octadecylamine (ODA) is introduced. The characteristics of the mixed P3HT/ODA Langmuir monolayers are investigated first and then, utilized as template layers to adsorb GOx from the subphase, preparing P3HT/ODA/GOx Langmuir-Blodgett films for glucose sensing. The results show that P3HT molecules tend to aggregate at the air/liquid interface and, furthermore, the P3HT monolayer has a weak ability to adsorb GOx from the subphase. By using mixed P3HT/ODA monolayer, the presence of ODA not only inhibits the aggregation of P3HT, but also increases the adsorption ability of the monolayer to GOx. The extensibility of P3HT and the homogeneity of the P3HT/ODA monolayers are closely related to the concentration of P3HT/ODA stock solutions. On the glucose sensing experiments, the performance of the P3HT/ODA/GOx LB film is greatly improved due to the presence of P3HT and, furthermore, the sensibility increases with increasing extensibility of P3HT molecules. The best sensitivity achieved for the P3HT/ODA/GOx film is 5.4μAmM -1 cm -2 which is over two times the value obtained by the ODA/GOx film (2.3μAmM -1 cm -2 ). Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Highly sensitive in-line microfluidic sensor based on microfiber-assisted Mach-Zehnder interferometer for glucose sensing

    Science.gov (United States)

    Xie, Nanjie; Zhang, Hao; Liu, Bo; Wu, Jixuan; Song, Binbin; Han, Tingting

    2017-11-01

    A highly sensitive microfluidic sensor based on a microfiber-assisted Mach-Zehnder interferometer (MAMZI) is proposed and experimentally demonstrated for the detection of low-concentration glucose solution. A segment of microfiber tapered from standard single-mode fiber (SMF) is spliced between two SMFs with pre-designed lateral offset to constitute the miniaturized MAMZI probe. The transmission spectral response to environmental refractive index variation has been experimentally investigated for glucose concentration ranges of 300 mg dL-1 to 3000 mg dL-1 and 0 to 270 mg dL-1 and the glucose concentration detection limit is 3 mg dL-1, and the experimentally observed transmission spectral responses are in accordance with our theoretical simulation results. Owing to its high sensitivity, non-enzymatic operation method, ease of fabrication and compact size, our proposed MAMZI for glucose sensing is anticipated to be employed in biomedical applications.

  7. Effect of platinum-nanodendrite modification on the glucose-sensing properties of a zinc-oxide-nanorod electrode

    Energy Technology Data Exchange (ETDEWEB)

    Abdul Razak, Khairunisak, E-mail: khairunisak@usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research & Innovation (NanoBRI), INFORMM, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Neoh, Soo Huan; Ridhuan, N.S.; Mohamad Nor, Noorhashimah [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2016-09-01

    Highlights: • Effect of PtNDs on ZnONRs/ITO glucose sensor was studied. • Well-defined PtNDs synthesis using 20 mM K{sub 2}PtCl{sub 4} produced good dispersion between nanodendrites with uniform particle size. • Nafion coating significantly improved the catalytic oxidation of glucose sensor. • Nafion/GO{sub x}/PtNDs/ZnONRs/ITO demonstrated better properties compared with Nafion/GO{sub x}/PtNDs/ITO and Nafion/GO{sub x}/ZnONRs/ITO electrodes. - Abstract: The properties of ZnO nanorods (ZnONRs) decorated with platinum nanodendrites (PtNDs) were studied. Various sizes of PtNDs were synthesized and spin coated onto ZnONRs, which were grown on indium–titanium–oxide (ITO) substrates through a low-temperature hydrothermal method. Scanning electron microscopy and X-ray diffraction analyses were conducted to analyze the morphology and structural properties of the electrodes. The effects of PtND size, glucose concentration, and Nafion amount on glucose-sensing properties were investigated. The glucose-sensing properties of electrodes with immobilized glucose oxidase (GO{sub x}) were measured using cyclic voltammetry. The bio-electrochemical properties of Nafion/GO{sub x}/42 nm PtNDs/ZnONRs/ITO glucose sensor was observed with linear range within 1–18 mM, with a sensitivity value of 5.85 μA/mM and a limit of detection of 1.56 mM. The results of this study indicate that PtNDs/ZnONRs/ITO has potential in glucose sensor applications.

  8. Approaching to DM2 through sodium-glucose cotransporter-2: does it make sense?

    Science.gov (United States)

    Segura, Julián

    2016-11-01

    The kidney is involved in glucose homeostasis through three main mechanisms: renal gluconeogenesis, renal glucose consumption and glucose reabsorption in the proximal tubule. Glucose reabsorption is one of the most relevant physiological functions of the kidney, through which filtered glucose is fully recovered, urine is free of glucose, and calorie loss is prevented. Approximately 90% of the glucose is reabsorbed in the S1 segment of the proximal tubule, where GLUT2 and SGLT2 transporters are located, while the remaining 10% is reabsorbed in the S3 segment by SGLT1 and GLUT1 transporters. In patients with hyperglycaemia, the kidney continues reabsorbing glucose, and hyperglycaemia is maintained. Most renal glucose reabsorption is mediated by the SGLT2 transporter. Several experimental and clinical studies suggest that pharmacological blockade of this transporter might be beneficial in the management of hyperglycemia in patients with type 2 diabetes. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

  9. The effects of critical illness on intestinal glucose sensing, transporters, and absorption.

    Science.gov (United States)

    Deane, Adam M; Rayner, Chris K; Keeshan, Alex; Cvijanovic, Nada; Marino, Zelia; Nguyen, Nam Q; Chia, Bridgette; Summers, Matthew J; Sim, Jennifer A; van Beek, Theresia; Chapman, Marianne J; Horowitz, Michael; Young, Richard L

    2014-01-01

    Providing effective enteral nutrition is important during critical illness. In health, glucose is absorbed from the small intestine via sodium-dependent glucose transporter-1 and glucose transporter-2, which may both be regulated by intestinal sweet taste receptors. We evaluated the effect of critical illness on glucose absorption and expression of intestinal sodium-dependent glucose transporter-1, glucose transporter-2, and sweet taste receptors in humans and mice. Prospective observational study in humans and mice. ICU and university-affiliated research laboratory. Human subjects were 12 critically ill patients and 12 healthy controls. In the laboratory 16-week-old mice were studied. Human subjects underwent endoscopy. Glucose (30 g) and 3-O-methylglucose (3 g), used to estimate glucose absorption, were infused intraduodenally over 30 minutes. Duodenal mucosa was biopsied before and after infusion. Mice were randomized to cecal ligation and puncture to model critical illness (n = 16) or sham laparotomy (control) (n = 8). At day 5, mice received glucose (100 mg) and 3-O-methylglucose (10 mg) infused intraduodenally prior to mucosal tissue collection. Quantitative polymerase chain reaction was performed to measure absolute (human) and relative levels of sodium-dependent glucose transporter-1, glucose transporter-2, and taste receptor type 1 member 2 (T1R2) transcripts. Blood samples were assayed for 3-O-methylglucose to estimate glucose absorption. Glucose absorption was three-fold lower in critically ill humans than in controls (p = 0.002) and reduced by a similar proportion in cecal ligation and puncture mice (p = 0.004). In critically ill patients, duodenal levels of sodium-dependent glucose transporter-1, glucose transporter-2, and T1R2 transcript were reduced 49% (p absorption, associated with reduced intestinal expression of glucose transporters (sodium-dependent glucose transporter-1 and glucose transporter-2) and sweet taste receptor transcripts

  10. Tunable emission in surface passivated Mn-ZnS nanophosphors and its application for Glucose sensing

    Directory of Open Access Journals (Sweden)

    Manoj Sharma

    2012-03-01

    Full Text Available The present work describes the tunable emission in inorganic-organic hybrid NPs which can be useful for optoelectronic and biosensing applications. In this work, Mn- ZnS nanoparticles emitting various colors, including blue and orange, were synthesized by simple chemical precipitation method using chitosan as a capping agent. Earlier reports describe that emission color characteristics in nanoparticles are tuned by varying particle size and with doping concentration. Here in this article tunable emission has been achieved by varying excitation wavelength in a single sample. This tunable emission property with high emission intensity was further achieved by changing capping concentration keeping host Mn-ZnS concentration same. Tunable emission is explained by FRET mechanism. Commission Internationale de l’Eclairage (CIE chromaticity coordinates shifts from (0.273, 0.20 and (0.344, 0.275 for same naocrystals by suitably tuning excitation energy from higher and lower ultra-violet (UV range. Synthesized nanoparticles have been characterized by X-ray diffraction, SEM, HRTEM, UV- Visible absorption and PL spectroscopy for structural and optical studies. Using tunable emission property, these highly emissive nanoparticles functionalized with biocompatible polymer chitosan were further used for glucose sensing applications.

  11. Bird Migration Echoes Observed by Polarimetric Radar

    OpenAIRE

    MINDA, Haruya; FURUZAWA, Fumie A.; SATOH, Shinsuke; NAKAMURA, Kenji

    2008-01-01

    A C-band polarimetric radar on Okinawa Island successfully observed large-scale bird migrations over the western Pacific Ocean. The birds generated interesting polarimetric signatures. This paper describes the signatures and speculates bird behavior.

  12. Sensitivity of Multiangle, Multispectral Polarimetric Remote Sensing Over Open Oceans to Water-Leaving Radiance: Analyses of RSP Data Acquired During the MILAGRO Campaign

    Science.gov (United States)

    Chowdhary, Jacek; Cairns, Brian; Waquet, Fabien; Knobelspiesse, Kirk; Ottaviani, Matteo; Redemann, Jens; Travis, Larry; Mishchenko, Michael

    2012-01-01

    For remote sensing of aerosol over the ocean, there is a contribution from light scattered underwater. The brightness and spectrum of this light depends on the biomass content of the ocean, such that variations in the color of the ocean can be observed even from space. Rayleigh scattering by pure sea water, and Rayleigh-Gans type scattering by plankton, causes this light to be polarized with a distinctive angular distribution. To study the contribution of this underwater light polarization to multiangle, multispectral observations of polarized reflectance over ocean, we previously developed a hydrosol model for use in underwater light scattering computations that produces realistic variations of the ocean color and the underwater light polarization signature of pure sea water. In this work we review this hydrosol model, include a correction for the spectrum of the particulate scattering coefficient and backscattering efficiency, and discuss its sensitivity to variations in colored dissolved organic matter (CDOM) and in the scattering function of marine particulates. We then apply this model to measurements of total and polarized reflectance that were acquired over open ocean during the MILAGRO field campaign by the airborne Research Scanning Polarimeter (RSP). Analyses show that our hydrosol model faithfully reproduces the water-leaving contributions to RSP reflectance, and that the sensitivity of these contributions to Chlorophyll a concentration [Chl] in the ocean varies with the azimuth, height, and wavelength of observations. We also show that the impact of variations in CDOM on the polarized reflectance observed by the RSP at low altitude is comparable to or much less than the standard error of this reflectance whereas their effects in total reflectance may be substantial (i.e. up to >30%). Finally, we extend our study of polarized reflectance variations with [Chl] and CDOM to include results for simulated spaceborne observations.

  13. Flexible 3D porous CuO nanowire arrays for enzymeless glucose sensing: in situ engineered versus ex situ piled

    Science.gov (United States)

    Huang, Jianfei; Zhu, Yihua; Yang, Xiaoling; Chen, Wei; Zhou, Ying; Li, Chunzhong

    2014-12-01

    Convenient determination of glucose in a sensitive, reliable and cost-effective way has aroused sustained research passion, bringing along assiduous investigation of high-performance electroactive nanomaterials to build enzymeless sensors. In addition to the intrinsic electrocatalytic capability of the sensing materials, electrode architecture at the microscale is also crucial for fully enhancing the performance. In this work, free-standing porous CuO nanowire (NW) was taken as a model sensing material to illustrate this point, where an in situ formed 3D CuO nanowire array (NWA) and CuO nanowires pile (NWP) immobilized with polymer binder by conventional drop-casting technique were both studied for enzymeless glucose sensing. The NWA electrode exhibited greatly promoted electrochemistry characterized by decreased overpotential for electro-oxidation of glucose and over 5-fold higher sensitivity compared to the NWP counterpart, benefiting from the binder-free nanoarray structure. Besides, its sensing performance was also satisfying in terms of rapidness, selectivity and durability. Further, the CuO NWA was utilized to fabricate a flexible sensor which showed excellent performance stability against mechanical bending. Thanks to its favorable electrode architecture, the CuO NWA is believed to offer opportunities for building high-efficiency flexible electrochemical devices.Convenient determination of glucose in a sensitive, reliable and cost-effective way has aroused sustained research passion, bringing along assiduous investigation of high-performance electroactive nanomaterials to build enzymeless sensors. In addition to the intrinsic electrocatalytic capability of the sensing materials, electrode architecture at the microscale is also crucial for fully enhancing the performance. In this work, free-standing porous CuO nanowire (NW) was taken as a model sensing material to illustrate this point, where an in situ formed 3D CuO nanowire array (NWA) and CuO nanowires

  14. A preliminary verification of the floating reference measurement method for non-invasive blood glucose sensing

    Science.gov (United States)

    Min, Xiaolin; Liu, Rong; Fu, Bo; Xu, Kexin

    2017-06-01

    In the non-invasive sensing of blood glucose by near-infrared diffuse reflectance spectroscopy, the spectrum is highly susceptible to the unstable and complicated background variations from the human body and the environment. In in vitro analyses, background variations are usually corrected by the spectrum of a standard reference sample that has similar optical properties to the analyte of interest. However, it is hard to find a standard sample for the in vivo measurement. Therefore, the floating reference measurement method is proposed to enable relative measurements in vivo, where the spectra under some special source-detector distance, defined as the floating reference position, are insensitive to the changes in glucose concentration due to the absorption effect and scattering effect. Because the diffuse reflectance signals at the floating reference positions only reflect the information on background variations during the measurement, they can be used as the internal reference. In this paper, the theoretical basis of the floating reference positions in a semi-infinite turbid medium was discussed based on the steady-state diffusion equation and its analytical solutions in a semi-infinite turbid medium (under the extrapolated boundary conditions). Then, Monte-Carlo (MC) simulations and in vitro experiments based on a custom-built continuous-moving spatially resolving double-fiber NIR measurement system, configured with two types of light source, a super luminescent diode (SLD) and a super-continuum laser, were carried out to verify the existence of the floating reference position in 5%, 10% and 20% Intralipid solutions. The results showed that the simulation values of the floating reference positions are close to the theoretical results, with a maximum deviation of approximately 0.3 mm in 1100-1320 nm. Great differences can be observed in 1340-1400 nm because the optical properties of Intralipid in this region don not satisfy the conditions of the steady

  15. Silver nanocluster films for glucose sensing by Surface Enhanced Raman Scattering (SERS

    Directory of Open Access Journals (Sweden)

    Raju Botta

    2016-07-01

    Full Text Available The detection of glucose by Surface Enhanced Raman Scattering (SERS is a challenging problem because glucose molecules have a small Raman scattering cross-section and they have a low affinity for adsorption on metal nanoparticle surfaces. In this study we used 2-Thienylboronic acid (2-TBA as a bridge or linker molecule between the metal surface and the glucose molecule and observed an intense Raman line at 986 cm−1 that was used to quantify the glucose concentration in the molar concentration range 1 μM–500 μM. A good correlation was observed between the intensity of this line and molar concentration of glucose. These results would find applications in the development of a non-invasive glucose sensor for diabetic patients using saliva as the body fluid instead of blood serum. Keywords: SERS, Nanoclusters, Raman Spectroscopy, 2-Thienylboronic acid, d-Glucose

  16. Continuous sensing of hydrogen peroxide and glucose via quenching of the UV and visible luminescence of ZnO nanoparticles

    International Nuclear Information System (INIS)

    Sodzel, Dzmitry; Kolesneva, Ekaterina; Dubovskaya, Lyudmila; Volotovski, Igor; Khranovskyy, Volodymyr; Eriksson, Martin O.; Holtz, Per-Olof; Yakimova, Rositsa; Beni, Valerio; Turner, Anthony P. F.; Ubelis, Arnolds; Smyntyna, Valentyn; Viter, Roman; Janot, Jean-Marc; Bechelany, Mikhael; Balme, Sebastien

    2015-01-01

    We report on an indirect optical method for the determination of glucose via the detection of hydrogen peroxide (H 2 O 2 ) that is generated during the glucose oxidase (GOx) catalyzed oxidation of glucose. It is based on the finding that the ultraviolet (∼374 nm) and visible (∼525 nm) photoluminescence of pristine zinc oxide (ZnO) nanoparticles strongly depends on the concentration of H 2 O 2 in water solution. Photoluminescence is quenched by up to 90 % at a 100 mM level of H 2 O 2 . The sensor constructed by immobilizing GOx on ZnO nanoparticles enabled glucose to be continuously monitored in the 10 mM to 130 mM concentration range, and the limit of detection is 10 mM. This enzymatic sensing scheme is supposed to be applicable to monitoring glucose in the food, beverage and fermentation industries. It has a wide scope in that it may be extended to numerous other substrate or enzyme activity assays based on the formation of H 2 O 2 , and of assays based on the consumption of H 2 O 2 by peroxidases. (author)

  17. An Icon-Based Synoptic Visualization of Fully Polarimetric Radar Data

    Directory of Open Access Journals (Sweden)

    Iain H. Woodhouse

    2012-03-01

    Full Text Available The visualization of fully polarimetric radar data is hindered by traditional remote sensing methodologies for displaying data due to the large number of parameters per pixel in such data, and the non-scalar nature of variables such as phase difference. In this paper, a new method is described that uses icons instead of image pixels to represent the image data so that polarimetric properties and geographic context can be visualized together. The icons are parameterized using the alpha-entropy decomposition of polarimetric data. The resulting image allows the following five variables to be displayed simultaneously: unpolarized power, alpha angle, polarimetric entropy, anisotropy and orientation angle. Examples are given for both airborne and laboratory-based imaging.

  18. CLEAN Technique for Polarimetric ISAR

    Directory of Open Access Journals (Sweden)

    M. Martorella

    2008-01-01

    Full Text Available Inverse synthetic aperture radar (ISAR images are often used for classifying and recognising targets. To reduce the amount of data processed by the classifier, scattering centres are extracted from the ISAR image and used for classifying and recognising targets. This paper addresses the problem of estimating the position and the scattering vector of target scattering centres from polarimetric ISAR images. The proposed technique is obtained by extending the CLEAN technique, which was introduced in radar imaging for extracting scattering centres from single-polarisation ISAR images. The effectiveness of the proposed algorithm, namely, the Polarimetric CLEAN (Pol-CLEAN is tested on simulated and real data.

  19. POLCAL - POLARIMETRIC RADAR CALIBRATION

    Science.gov (United States)

    Vanzyl, J.

    1994-01-01

    Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the

  20. Polarimetric optimization for clutter suppression in spectral polarimetric weather radar

    NARCIS (Netherlands)

    Yin, J.; Unal, C.M.H.; Russchenberg, H.W.J.

    2017-01-01

    For the polarimetric-Doppler weather radar, sometimes there are artifacts caused by radar system itself or external sources displaying in the radar plan position indicator (PPI). These artifacts are not confined to specific range bins and also they are non-stationary when observed in the Doppler

  1. Forest biomass estimation from polarimetric SAR interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Mette, T.

    2007-07-01

    Polarimetric SAR interferometry (Pol-InSAR) is a radar remote sensing technique that allows extracting forest heights by means of model-based inversions. Forest biomass is closely related to forest height, and can be derived from it with allometric relations. This work investigates the combination of the two methods to estimate forest biomass from Pol-InSAR. It develops a concept for the use of height-biomass allometry, and outlines the Pol-InSAR height inversion. The methodology is validated against a set of forest inventory data and Pol-InSAR data at L-band of the test site Traunstein. The results allow drawing conclusions on the potential of Pol-InSAR forest biomass missions. (orig.)

  2. Utilizing microfluidics to synthesize polyethylene glycol microbeads for Förster resonance energy transfer based glucose sensing

    Science.gov (United States)

    Kantak, Chaitanya; Zhu, Qingdi; Beyer, Sebastian; Bansal, Tushar; Trau, Dieter

    2012-01-01

    Here, we utilize microfluidic droplet technology to generate photopolymerizeable polyethylene glycol (PEG) hydrogel microbeads incorporating a fluorescence-based glucose bioassay. A microfluidic T-junction and multiphase flow of fluorescein isothiocyanate dextran, tetramethyl rhodamine isothiocyanate concanavalin A, and PEG in water were used to generate microdroplets in a continuous stream of hexadecane. The microdroplets were photopolymerized mid-stream with ultraviolet light exposure to form PEG microbeads and were collected at the outlet for further analysis. Devices were prototyped in PDMS and generated highly monodisperse 72 ± 2 μm sized microbeads (measured after transfer into aqueous phase) at a continuous flow rate between 0.04 ml/h—0.06 ml/h. Scanning electron microscopy analysis was conducted to analyze and confirm microbead integrity and surface morphology. Glucose sensing was carried out using a Förster resonance energy transfer (FRET) based assay. A proportional fluorescence intensity increase was measured within a 1–10 mM glucose concentration range. Microfluidically synthesized microbeads encapsulating sensing biomolecules offer a quick and low cost method to generate monodisperse biosensors for a variety of applications including cell cultures systems, tissue engineering, etc. PMID:22655010

  3. The global regulatory system Csr senses glucose through the phosphoenolpyruvate: carbohydrate phosphotransferase system.

    Science.gov (United States)

    Pérez-Morales, Deyanira; Bustamante, Víctor H

    2016-02-01

    A novel connection between two regulatory systems controlling crucial biological processes in bacteria, the carbon storage regulator (Csr) system and the glucose-specific phosphotransferase system (PTS), is reported by Leng et al. in this issue. This involves the interaction of unphosphorylated EIIA(Glc), a component of the glucose-specific PTS, with the CsrD protein, which accelerates the decay of the CsrB and CsrC small RNAs via RNase E in Escherichia coli. As unphosphorylated EIIA(G) (lc) is generated in the presence of glucose, the PTS thus acts as a sensor of glucose for the Csr system. Interestingly, another pathway can operate for communication between the Csr system and the glucose-specific PTS. The absence of glucose generates phosphorylated EIIA(Glc) , which activates the enzyme adenylate cyclase to produce cyclic adenosine monophosphate (cAMP) that, in turn, binds to the regulator cAMP receptor protein (CRP). Leng et al. show that the complex cAMP-CRP modestly reduces CsrB decay independently of CsrD. On the other hand, a previous study indicates that the complex cAMP-CRP positively regulates the transcription of CsrB and CsrC in Salmonella enterica. Therefore, EIIA(G) (lc) could work as a molecular switch that regulates the activity of the Csr system, in response to its phosphorylation state determined by the presence or absence of glucose, in order to control gene expression. © 2015 John Wiley & Sons Ltd.

  4. Investigation on how to choose measurement sites for non-invasive near-infrared blood glucose sensing

    Science.gov (United States)

    Jiang, Jingying; Zou, Da; Min, Xiaolin; Ma, Zhenhe; Xu, Kexin

    2012-03-01

    With the changing of human diet and the future of an aging society, the number of diabetic patients is growing rapidly and steadily. The major therapeutic method to that disease is monitoring the blood glucose concentration frequently to adjust the dose of the drugs and insulin. In order to avoid the painful finger prick, we choose the ear lobe as a measurement site with finger as a reference. Firstly, we compare the blood glucose concentration results of ear lobe and finger during an oral glucose tolerance test, the results showed a good correlation of the two sites. Secondly, the three-layered skin structure of finger and ear lobe has been studied by using optical coherence tomography (OCT) technique. The result shows that the thickness of each layer at ear lobe is thinner. Finally, the difference between reflectance spectra of finger and ear lobe is compared due to the diverse skin thickness. The results still show a higher absorbance value for ear lobe. In conclusion, the ear lobe is an ideal measurement site for noninvasive blood glucose sensing.

  5. All-Plastic Electrochemical Transistor for Glucose Sensing Using a Ferrocene Mediator

    Directory of Open Access Journals (Sweden)

    George G. Malliaras

    2009-12-01

    Full Text Available We demonstrate a glucose sensor based on an organic electrochemical transistor (OECT in which the channel, source, drain, and gate electrodes are made from the conducting polymer poly(3,4-ethylenedioxythiophene doped with poly(styrene sulfonate (PEDOT:PSS. The OECT employs a ferrocene mediator to shuttle electrons between the enzyme glucose oxidase and a PEDOT:PSS gate electrode. The device can be fabricated using a one-layer patterning process and offers glucose detection down to the micromolar range, consistent with levels present in human saliva.

  6. A large-area, wide-incident-angle, and polarization-independent plasmonic color filter for glucose sensing

    Science.gov (United States)

    Lin, Yu-Sheng; Chen, Wenjun

    2018-01-01

    We develop an effective method for glucose sensing by using a plasmonic color filter (PCF) integrated with a microfluidic chip. The morphology of PCF is composed of hybrid nanopillars fabricated with SiO2 and Au thin-films on silicon substrate. It exhibits angle-independence, polarization-independence and wafer-level fabrication, which are the most important factors for color filters for industrial applications. The shift of resonant wavelength is 56 nm with a stable bandwidth (∼30 nm) by varying concentration of glucose solution. The sensitivity is 157.61 nm/RIU and the corresponding figure-of-merit is 5.25. Such strategy can be exploited to further increase the detection and potentially enter the ultra-strong coupling regime in chemical solution sensors.

  7. High-performance electrochemical glucose sensing enabled by Cu(TCNQ) nanorod array

    Science.gov (United States)

    Wu, Xiufeng; Lu, Wenbo

    2018-04-01

    It is highly attractive to construct stable enzyme-free glucose sensors based on three-dimensional direct electrochemical detection of glucose. In this paper, a copper 7,7,8,8-tetracyanoquinodimethane (Cu(TCNQ)) nanorod array on Cu foam (Cu(TCNQ) NA/CF) is proposed as an efficient catalyst for electrochemical glucose oxidation in alkaline conditions. When Cu(TCNQ) NA/CF was used as the enzyme-free sensory of glucose, the sensor showed a response time within 3 s, a wide linear detection in the range 0.001-10.0 mM, the minimum limit of detection was as low as 10 nM (S/N = 3), and it had a high sensitivity of 26 987 μA mM-1 cm-2. Moreover, this sensor also possesses long-term stability, high selectivity, reproducibility, and actual applications for fresh human serum sample analysis is also successfully accepted.

  8. Facile fabrication of nanoporous PdFe alloy for nonenzymatic electrochemical sensing of hydrogen peroxide and glucose

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinping [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Wang, Zhihong [School of Basic Medical Sciences, Shandong University of Traditional Chinese Medicine, Jinan 250355 (China); Zhao, Dianyun [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Xu, Caixia, E-mail: chm_xucx@ujn.edu.cn [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2014-06-01

    Graphical abstract: Nanoporous PdFe alloy, characterized by open three-dimensional bicontinuous nanospongy architecture, was easily fabricated by selectively dealloying PdFeAl source alloys, which exhibits greatly enhanced sensing performance and structure stability towards H{sub 2}O{sub 2} and glucose compared with NP-Pd and Pd/C catalysts. - Highlights: • NP-PdFe alloy is fabricated by a simple dealloying method. • NP-PdFe possesses open three-dimensional bicontinuous spongy morphology. • NP-PdFe shows high electrochemical sensing activities towards H{sub 2}O{sub 2} and glucose. • NP-PdFe shows good long-term stability for H{sub 2}O{sub 2} and glucose detection. • NP-PdFe shows good reproducibility for H{sub 2}O{sub 2} and glucose detection. - Abstract: Nanoporous (NP) PdFe alloy is easily fabricated through one step mild dealloying of PdFeAl ternary source alloy in NaOH solution. Electron microscopy characterization demonstrates that selectively dissolving Al from PdFeAl alloy generates three-dimensional bicontinuous nanospongy architecture with the typical ligament size around 5 nm. Electrochemical measurements show that the NP-PdFe alloy exhibits the superior electrocatalytic activity and durability towards hydrogen peroxide (H{sub 2}O{sub 2}) detection compared with NP-Pd and commercial Pd/C catalysts. In addition, NP-PdFe performs high sensing performance towards H{sub 2}O{sub 2} in a wide linear range from 0.5 to 6 mM with a low detection limit of 2.1 μM. This nanoporous structure also can sensitively detect glucose over a wide concentration range (1–32 mM) with a low detection limit of 1.6 μM and high resistance against chloride ions. Along with these attractive features, the as-made NP-PdFe alloy also has a good anti-interference towards ascorbic acid, uric acid, and dopamine.

  9. Palladium nanoparticles deposited on graphene and its electrochemical performance for glucose sensing

    Science.gov (United States)

    Mijowska, Ewa; Onyszko, Magdalena; Urbas, Karolina; Aleksandrzak, Malgorzata; Shi, Xiaoze; Moszyński, Dariusz; Penkala, Krzysztof; Podolski, Jacek; El Fray, Mirosława

    2015-11-01

    This paper reports on the fabrication and characterization of glucose oxidase (GOx) immobilized onto a glassy carbon electrode (GCE) modified with reduced graphene oxide/palladium nanocomposite (RGO-Pd). Characterization tools showed well dispersed uniform Pd nanoparticles on a partly reduced graphene oxide surface. Cyclic voltammetry demonstrated successful immobilization of GOx on RGO-Pd modified GCE (GCE-RGO-Pd) using covalent bonding of GOx with RGO-Pd (RGO-Pd-GOx). Therefore, it was used as an electrochemical biosensor of glucose. RGO-Pd-GOx exhibited good electrocatalysis toward glucose in different glucose concentrations (from 2 to 10 mM, which includes the blood glucose levels of both normal and diabetic persons) with O2 saturated phosphate buffer solution (PBS) at pH 7.4. The system showed a linear increase in current at potential -0.085 V in the concentration range examined, with a correlation coefficient of 0.996. The sensitivity of the biosensor was 41.3 μA cm-2 mM-1, suggesting that RGO-Pd-GOx-modified GCE could be a potential candidate as a glucose sensor.

  10. EMISAR: A Dual-frequency, Polarimetric Airborne SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2002-01-01

    . The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry....... Thermal control and several calibration loops have been built into the system to ensure system stability and absolute calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key......EMISAR is a fully polarimetric, dual frequency (L- and C-band) SAR system designed for remote sensing applications. The data are usually processed to 2×2 m resolution. The system has the capability of C-band cross-track single-pass interferometry and fully polarimetric repeat-pass interferometry...

  11. Polarimetric Segmentation Using Wishart Test Statistic

    DEFF Research Database (Denmark)

    Skriver, Henning; Schou, Jesper; Nielsen, Allan Aasbjerg

    2002-01-01

    ) approach, which is a merging algorithm for single channel SAR images. The polarimetric version described in this paper uses the above-mentioned test statistic for merging. The segmentation algorithm has been applied to polarimetric SAR data from the Danish dual-frequency, airborne polarimetric SAR, EMISAR......A newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic has been used in a segmentation algorithm. The segmentation algorithm is based on the MUM (merge using moments....... The results show clearly an improved segmentation performance for the full polarimetric algorithm compared to single channel approaches....

  12. ASTEROID POLARIMETRIC DATABASE V3.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  13. ASTEROID POLARIMETRIC DATABASE V4.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  14. ASTEROID POLARIMETRIC DATABASE V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  15. ASTEROID POLARIMETRIC DATABASE V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is compiled by Dmitrij Lupishko of Kharkov University. This database tabulates the original data comprising degree of...

  16. The potential of Internet of m-health Things "m-IoT" for non-invasive glucose level sensing.

    Science.gov (United States)

    Istepanian, R S H; Hu, S; Philip, N Y; Sungoor, A

    2011-01-01

    An amalgamated concept of Internet of m-health Things (m-IoT) has been introduced recently and defined as a new concept that matches the functionalities of m-health and IoT for a new and innovative future (4G health) applications. It is well know that diabetes is a major chronic disease problem worldwide with major economic and social impact. To-date there have not been any studies that address the potential of m-IoT for non-invasive glucose level sensing with advanced opto-physiological assessment technique and diabetes management. In this paper we address the potential benefits of using m-IoT in non-invasive glucose level sensing and the potential m-IoT based architecture for diabetes management. We expect to achieve intelligent identification and management in a heterogeneous connectivity environment from the mobile healthcare perspective. Furthermore this technology will enable new communication connectivity routes between mobile patients and care services through innovative IP based networking architectures.

  17. Electrodeposition of copper nanoparticles using pectin scaffold at graphene nanosheets for electrochemical sensing of glucose and hydrogen peroxide

    International Nuclear Information System (INIS)

    Mani, Veerappan; Devasenathipathy, Rajkumar; Chen, Shen-Ming; Wang, Sea-Fue; Devi, Parvathy; Tai, Yian

    2015-01-01

    A simple electrodeposition approach has been described for the preparation of copper nanoparticles (CuNPs) using biopolymer pectin as a scaffold and graphene as a support. The formation of graphene/pectin-CuNPs was confirmed by scanning electron microscopy, UV-Visible spectroscopy and X-ray diffraction studies. The graphene/pectin-CuNPs film modified electrode was prepared and its electrocatalytic applications to the oxidation of glucose and reduction of H 2 O 2 have been explored. An amperometric glucose sensor was fabricated which exhibited excellent sensor performance in terms of wide linear range (10 μM–5.5 mM), low detection limit (2.1 μM) and high sensitivity (0.0457 μAμM −1 cm −2 ). Likewise, an amperometric sensor has been fabricated for the determination of H 2 O 2 which displayed linear range of 1 μM–1 mM, detection limit of 0.35 μM and sensitivity of 0.391 μAμM −1 cm −2 . The sensor displayed appreciable repeatability, reproducibity and stability. Furthermore, practical feasibility of the sensor has been demonstrated in human serum and contact lens cleaning solution to determine glucose and H 2 O 2 , respectively. The main advantages of sensor include simple and green fabrication approach, roughed and stable electrode matrix, high sensitivity and stability, fast in sensing and highly reproducible

  18. Science Drivers for Polarimetric Exploration

    Science.gov (United States)

    Yanamandra-Fisher, Padma

    2017-04-01

    The versatility of polarimetric exploration is exploited to address: (1) understanding the formation of planetary systems and their diversity; and (2) search for habitability. Polarized light occurs in three states: unpolarized, linear and circularized. Each mode of polarized light provides information about the scattering medium, from atmospheres to search for signatures of habitability. Spectral dependence of polarization is important to separate the macroscopic (bulk) properties of the scattering medium from the microscopic (particulate) properties of the scattering medium. Linear polarization of reflected light by solar system objects provides insight into the scattering characteristics of aerosols and hazes in atmospheres and surficial properties of atmosphereless objects, circular polarization and related chirality (or handedness, a property of molecules that exhibit mirror-image symmetry, similar to right and left hands) can serve as diagnostic of biological activity. Atmospheric phenomena such as rainbows, clouds and haloes exhibit polarimetric signatures that can be used as diagnostics to probe the atmosphere and may be possible to extend this approach to other planets and exoplanets. Biological molecules exhibit an inherent handedness or circular polarization or chirality, assisting in search for the identification of astrobiological material in the solar system. Polarimetry is also utilized in the exploration of comets, asteroids, dust/regoliths. Renewed efforts for ground-based polarimetry are emerging, from probing planetary atmospheres to the study of magnetic field lines and taxonomy of asteroids. While imaging and spectroscopy are routinely performed by amateurs, there is growing interest and progress in developing polarimetric exploration amongst the amateur community, with encouraging results.I will present a review of these efforts and the goal to create a global " PACA* Polarimetry Network" of observers, modelers and instrument experts to fully

  19. O-GlcNAcylation links ChREBP and FXR to glucose-sensing

    Directory of Open Access Journals (Sweden)

    Fadila eBenhamed

    2015-01-01

    Full Text Available Accumulating evidence suggests that O-GlcNAc transferase (OGT, an enzyme responsible for O-GlcNAc post-translational modification acts as a nutrient sensor that links glucose and the hexosamine biosynthetic pathway to the regulation of transcriptional factors involved in energy homeostasis. In liver, glucose signaling is mediated by ChREBP (carbohydrate response element binding protein which stimulates glycolytic and lipogenic gene expression through its binding on a specific ChoRE DNA sequence. Modulation of ChREBP by O-GlcNAcylation increases its DNA binding affinity and its activity. ChREBP transcriptional activity also depends on the presence of several other co-factors and transcriptional factors. Among them, the nuclear Farnesoid X Receptor (FXR, a key transcription factor of bile acid metabolism involved in the gut-liver axis homeostasis was recently shown to directly interact with ChREBP, acting as a repressor on the ChoRE of glycolytic genes. Interestingly, similarly to ChREBP, FXR is O-GlcNAcylated in response to glucose. This review discusses the importance of ChREBP and FXR modification through O-GlcNAcylation in liver and how glucose can modify their mutual affinity and transcriptional activity.

  20. Brain Glucose Metabolism Controls Hepatic Glucose and Lipid Production

    OpenAIRE

    Lam, Tony K.T.

    2007-01-01

    Brain glucose-sensing mechanisms are implicated in the regulation of feeding behavior and hypoglycemic-induced hormonal counter-regulation. This commentary discusses recent findings indicating that the brain senses glucose to regulate both hepatic glucose and lipid production.

  1. Glycogen metabolism in the glucose-sensing and supply-driven β-cell.

    Science.gov (United States)

    Andersson, Lotta E; Nicholas, Lisa M; Filipsson, Karin; Sun, Jiangming; Medina, Anya; Al-Majdoub, Mahmoud; Fex, Malin; Mulder, Hindrik; Spégel, Peter

    2016-12-01

    Glycogen metabolism in β-cells may affect downstream metabolic pathways controlling insulin release. We examined glycogen metabolism in human islets and in the rodent-derived INS-1 832/13 β-cells and found them to express the same isoforms of key enzymes required for glycogen metabolism. Our findings indicate that glycogenesis is insulin-independent but influenced by extracellular glucose concentrations. Levels of glycogen synthase decrease with increasing glucose concentrations, paralleling accumulation of glycogen. We did not find cAMP-elicited glycogenolysis and insulin secretion to be causally related. In conclusion, our results reveal regulated glycogen metabolism in human islets and insulin-secreting cells. Whether glycogen metabolism affects insulin secretion under physiological conditions remains to be determined. © 2016 Federation of European Biochemical Societies.

  2. RADARSAT-2 Polarimetric Radar Imaging for Lake Ice Mapping

    Science.gov (United States)

    Pan, F.; Kang, K.; Duguay, C. R.

    2016-12-01

    Changes in lake ice dates and duration are useful indicators for assessing long-term climate trends and variability in northern countries. Lake ice cover observations are also a valuable data source for predictions with numerical ice and weather forecasting models. In recent years, satellite remote sensing has assumed a greater role in providing observations of lake ice cover extent for both modeling and climate monitoring purposes. Polarimetric radar imaging has become a promising tool for lake ice mapping at high latitudes where meteorological conditions and polar darkness severely limit observations from optical sensors. In this study, we assessed and characterized the physical scattering mechanisms of lake ice from fully polarimetric RADARSAT-2 datasets obtained over Great Bear Lake, Canada, with the intent of classifying open water and different ice types during the freeze-up and break-up periods. Model-based and eigen-based decompositions were employed to construct the coherency matrix into deterministic scattering mechanisms. These procedures as well as basic polarimetric parameters were integrated into modified convolutional neural networks (CNN). The CNN were modified via introduction of a Markov random field into the higher iterative layers of networks for acquiring updated priors and classifying ice and open water areas over the lake. We show that the selected polarimetric parameters can help with interpretation of radar-ice/water interactions and can be used successfully for water-ice segmentation, including different ice types. As more satellite SAR sensors are being launched or planned, such as the Sentinel-1a/b series and the upcoming RADARSAT Constellation Mission, the rapid volume growth of data and their analysis require the development of robust automated algorithms. The approach developed in this study was therefore designed with the intent of moving towards fully automated mapping of lake ice for consideration by ice services.

  3. Target detection and recognition with polarimetric SAR

    NARCIS (Netherlands)

    Dekker, R.J.; Broek, A.C. van den

    2000-01-01

    Target detection and recognition using polarimetric SAR data has been studied by using PHARUS and RAMSES data collected during the MIMEX campaign. Additionally very high-resolution ISAR data was used. A basic detection and recognition scheme has been developed, which includes polarimetric

  4. Space-borne polarimetric SAR sensors or the golden age of radar polarimetry

    Directory of Open Access Journals (Sweden)

    Pottier E.

    2010-06-01

    Full Text Available SAR Polarimetry represents an active area of research in Active Earth Remote Sensing. This interest is clearly supported by the fact that nowadays there exists, or there will exist in a very next future, a non negligible quantity of launched Polarimetric SAR Spaceborne sensors. The ENVISAT satellite, developed by ESA, was launched on March 2002, and was the first Spaceborne sensor offering an innovative dualpolarization Advanced Synthetic Aperture Radar (ASAR system operating at C-band. The second Polarimetric Spaceborne sensor is ALOS, a Japanese Earth-Observation satellite, developed by JAXA and was launched in January 2006. This mission includes an active L-band polarimetric radar sensor (PALSAR whose highresolution data may be used for environmental and hazard monitoring. The third Polarimetric Spaceborne sensor is TerraSAR-X, a new German radar satellite, developed by DLR, EADS-Astrium and Infoterra GmbH, was launched on June 2007. This sensor carries a dual-polarimetric and high frequency X-Band SAR sensor that can be operated in different modes and offers features that were not available from space before. At least, the Polarimetric Spaceborne sensor, developed by CSA and MDA, and named RADARSAT-2 was launched in December 2007 The Radarsat program was born out the need for effective monitoring of Canada’s icy waters, and some Radarsat-2 capabilities that benefit sea- and river ice applications are the multi-polarization options that will improve ice-edge detection, ice-type discrimination and structure information. The many advances in these different Polarimetric Spaceborne platforms were developed to respond to specific needs for radar data in environmental monitoring applications around the world, like : sea- and river-ice monitoring, marine surveillance, disaster management, oil spill detection, snow monitoring, hydrology, mapping, geology, agriculture, soil characterisation, forestry applications (biomass, allometry, height

  5. CuO nanowire/microflower/nanowire modified Cu electrode with enhanced electrochemical performance for non-enzymatic glucose sensing.

    Science.gov (United States)

    Li, Changli; Yamahara, Hiroyasu; Lee, Yaerim; Tabata, Hitoshi; Delaunay, Jean-Jacques

    2015-07-31

    CuO nanowire/microflower structure on Cu foil is synthesized by annealing a Cu(OH)2 nanowire/CuO microflower structure at 250 °C in air. The nanowire/microflower structure with its large surface area leads to an efficient catalysis and charge transfer in glucose detection, achieving a high sensitivity of 1943 μA mM(-1) cm(-2), a wide linear range up to 4 mM and a low detection limit of 4 μM for amperometric glucose sensing in alkaline solution. With a second consecutive growth of CuO nanowires on the microflowers, the sensitivity of the obtained CuO nanowire/microflower/nanowire structure further increases to 2424 μA mM(-1) cm(-2), benefiting from an increased number of electrochemically active sites. The enhanced electrocatalytic performance of the CuO nanowire/microflower/nanowire electrode compared to the CuO nanowire/microflower electrode, CuO nanowire electrode and CuxO film electrode provides evidence for the significant role of available surface area for electrocatalysis. The rational combination of CuO nanowire and microflower nanostructures into a nanowire supporting microflower branching nanowires structure makes it a promising composite nanostructure for use in CuO based electrochemical sensors with promising analytical properties.

  6. Forest Structure Characterization Using Jpl's UAVSAR Multi-Baseline Polarimetric SAR Interferometry and Tomography

    Science.gov (United States)

    Neumann, Maxim; Hensley, Scott; Lavalle, Marco; Ahmed, Razi

    2013-01-01

    This paper concerns forest remote sensing using JPL's multi-baseline polarimetric interferometric UAVSAR data. It presents exemplary results and analyzes the possibilities and limitations of using SAR Tomography and Polarimetric SAR Interferometry (PolInSAR) techniques for the estimation of forest structure. Performance and error indicators for the applicability and reliability of the used multi-baseline (MB) multi-temporal (MT) PolInSAR random volume over ground (RVoG) model are discussed. Experimental results are presented based on JPL's L-band repeat-pass polarimetric interferometric UAVSAR data over temperate and tropical forest biomes in the Harvard Forest, Massachusetts, and in the La Amistad Park, Panama and Costa Rica. The results are partially compared with ground field measurements and with air-borne LVIS lidar data.

  7. Application of Deep Networks to Oil Spill Detection Using Polarimetric Synthetic Aperture Radar Images

    Directory of Open Access Journals (Sweden)

    Guandong Chen

    2017-09-01

    Full Text Available Polarimetric synthetic aperture radar (SAR remote sensing provides an outstanding tool in oil spill detection and classification, for its advantages in distinguishing mineral oil and biogenic lookalikes. Various features can be extracted from polarimetric SAR data. The large number and correlated nature of polarimetric SAR features make the selection and optimization of these features impact on the performance of oil spill classification algorithms. In this paper, deep learning algorithms such as the stacked autoencoder (SAE and deep belief network (DBN are applied to optimize the polarimetric feature sets and reduce the feature dimension through layer-wise unsupervised pre-training. An experiment was conducted on RADARSAT-2 quad-polarimetric SAR image acquired during the Norwegian oil-on-water exercise of 2011, in which verified mineral, emulsions, and biogenic slicks were analyzed. The results show that oil spill classification achieved by deep networks outperformed both support vector machine (SVM and traditional artificial neural networks (ANN with similar parameter settings, especially when the number of training data samples is limited.

  8. Polarimetric microlensing of circumstellar discs

    Science.gov (United States)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  9. Wavelength selection-based nonlinear calibration for transcutaneous blood glucose sensing using Raman spectroscopy

    Science.gov (United States)

    Dingari, Narahara Chari; Barman, Ishan; Kang, Jeon Woong; Kong, Chae-Ryon; Dasari, Ramachandra R.; Feld, Michael S.

    2011-01-01

    While Raman spectroscopy provides a powerful tool for noninvasive and real time diagnostics of biological samples, its translation to the clinical setting has been impeded by the lack of robustness of spectroscopic calibration models and the size and cumbersome nature of conventional laboratory Raman systems. Linear multivariate calibration models employing full spectrum analysis are often misled by spurious correlations, such as system drift and covariations among constituents. In addition, such calibration schemes are prone to overfitting, especially in the presence of external interferences that may create nonlinearities in the spectra-concentration relationship. To address both of these issues we incorporate residue error plot-based wavelength selection and nonlinear support vector regression (SVR). Wavelength selection is used to eliminate uninformative regions of the spectrum, while SVR is used to model the curved effects such as those created by tissue turbidity and temperature fluctuations. Using glucose detection in tissue phantoms as a representative example, we show that even a substantial reduction in the number of wavelengths analyzed using SVR lead to calibration models of equivalent prediction accuracy as linear full spectrum analysis. Further, with clinical datasets obtained from human subject studies, we also demonstrate the prospective applicability of the selected wavelength subsets without sacrificing prediction accuracy, which has extensive implications for calibration maintenance and transfer. Additionally, such wavelength selection could substantially reduce the collection time of serial Raman acquisition systems. Given the reduced footprint of serial Raman systems in relation to conventional dispersive Raman spectrometers, we anticipate that the incorporation of wavelength selection in such hardware designs will enhance the possibility of miniaturized clinical systems for disease diagnosis in the near future. PMID:21895336

  10. ASTEROID POLARIMETRIC DATABASE V6.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  11. ASTEROID POLARIMETRIC DATABASE V7.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko and S.V. Vasiliev of Karazin Kharkiv National...

  12. ASTEROID POLARIMETRIC DATABASE V8.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  13. ASTEROID POLARIMETRIC DATABASE V5.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Polarimetric Database (APD) is a collection of asteroid polarimetry results compiled by D.F. Lupishko of Karazin Kharkiv National University, Ukraine....

  14. Novel Polarimetric SAR Interferometry Algorithms, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...

  15. Novel Polarimetric SAR Interferometry Algorithms, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  16. Tuning the pure monoclinic phase of WO3 and WO3-Ag nanostructures for non-enzymatic glucose sensing application with theoretical insight from electronic structure simulations

    Science.gov (United States)

    Ponnusamy, Rajeswari; Gangan, Abhijeet; Chakraborty, Brahmananda; Sekhar Rout, Chandra

    2018-01-01

    Here, we report the controlled hydrothermal synthesis and tuning of the pure monoclinic phase of WO3 and WO3-Ag nanostructures. Comparative electrochemical nonenzymatic glucose sensing properties of WO3 and WO3-Ag were investigated by cyclic voltammetry and chronoamperometric tests. We observed enhanced glucose sensing performance of WO3-Ag porous spheres as compared to bare WO3 nanoslabs. The sensitivity of the pure WO3 nanoslabs is 11.1 μA μM-1 cm-2 whereas WO3-Ag porous spheres exhibit sensitivity of 23.3 μA μM-1 cm-2. The WO3-Ag porous spheres exhibited a good linear range (5-375 μM) with excellent anti-interference property. Our experimental observations are qualitatively supported by density functional theory simulations through investigation of bonding and charge transfer mechanism of glucose on WO3 and Ag doped WO3. As the binding energy of glucose is more on the Ag doped WO3 (100) surface compared to the bare WO3 (100) surface and the Ag doped WO3 (100) surface becomes more conducting due to enhancement of density of states near the Fermi level, we can infer that Ag doped WO3 exhibits a better charge transfer media compared to bare WO3 resulting in enhanced glucose sensitivity in consistency with our experimental data.

  17. PolSAR Land Cover Classification Based on Roll-Invariant and Selected Hidden Polarimetric Features in the Rotation Domain

    Directory of Open Access Journals (Sweden)

    Chensong Tao

    2017-07-01

    Full Text Available Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR. Target polarimetric response is strongly dependent on its orientation. Backscattering responses of the same target with different orientations to the SAR flight path may be quite different. This target orientation diversity effect hinders PolSAR image understanding and interpretation. Roll-invariant polarimetric features such as entropy, anisotropy, mean alpha angle, and total scattering power are independent of the target orientation and are commonly adopted for PolSAR image classification. On the other aspect, target orientation diversity also contains rich information which may not be sensed by roll-invariant polarimetric features. In this vein, only using the roll-invariant polarimetric features may limit the final classification accuracy. To address this problem, this work uses the recently reported uniform polarimetric matrix rotation theory and a visualization and characterization tool of polarimetric coherence pattern to investigate hidden polarimetric features in the rotation domain along the radar line of sight. Then, a feature selection scheme is established and a set of hidden polarimetric features are selected in the rotation domain. Finally, a classification method is developed using the complementary information between roll-invariant and selected hidden polarimetric features with a support vector machine (SVM/decision tree (DT classifier. Comparison experiments are carried out with NASA/JPL AIRSAR and multi-temporal UAVSAR data. For AIRSAR data, the overall classification accuracy of the proposed classification method is 95.37% (with SVM/96.38% (with DT, while that of the conventional classification method is 93.87% (with SVM/94.12% (with DT, respectively. Meanwhile, for multi-temporal UAVSAR data, the mean overall classification accuracy of the proposed method is up to 97.47% (with SVM/99.39% (with DT, which is also higher

  18. Microphysical retrievals from simultaneous polarimetric and profiling radar observations

    Directory of Open Access Journals (Sweden)

    M. P. Morris

    2009-12-01

    Full Text Available The character of precipitation detected at the surface is the final product of many microphysical interactions in the cloud above, the combined effects of which may be characterized by the observed drop size distribution (DSD. This necessitates accurate retrieval of the DSD from remote sensing data, especially radar as it offers large areal coverage, high spatial resolution, and rigorous quality control and testing. Combined instrument observations with a UHF wind profiler, an S-band polarimetric weather radar, and a video disdrometer are analyzed for two squall line events occuring during the calendar year 2007. UHF profiler Doppler velocity spectra are used to estimate the DSD aloft, and are complemented by DSDs retrieved from an exponential model applied to polarimetric data. Ground truth is provided by the disdrometer. A complicating factor in the retrieval from UHF profiler spectra is the presence of ambient air motion, which can be corrected using the method proposed by Teshiba et al. (2009, in which a comparison between idealized Doppler spectra calculated from the DSDs retrieved from KOUN and those retrieved from contaminated wind profiler spectra is performed. It is found that DSDs measured using the distrometer at the surface and estimated using the wind profiler and polarimetric weather radar generally showed good agreement. The DSD retrievals using the wind profiler were improved when the estimates of the vertical wind were included into the analysis, thus supporting the method of Teshiba et al. (2009. Furthermore, the the study presents a method of investigating the time and height structure of DSDs.

  19. Validation of Distributed Soil Moisture: Airborne Polarimetric SAR vs. Ground-based Sensor Networks

    Science.gov (United States)

    Jagdhuber, T.; Kohling, M.; Hajnsek, I.; Montzka, C.; Papathanassiou, K. P.

    2012-04-01

    The knowledge of spatially distributed soil moisture is highly desirable for an enhanced hydrological modeling in terms of flood prevention and for yield optimization in combination with precision farming. Especially in mid-latitudes, the growing agricultural vegetation results in an increasing soil coverage along the crop cycle. For a remote sensing approach, this vegetation influence has to be separated from the soil contribution within the resolution cell to extract the actual soil moisture. Therefore a hybrid decomposition was developed for estimation of soil moisture under vegetation cover using fully polarimetric SAR data. The novel polarimetric decomposition combines a model-based decomposition, separating the volume component from the ground components, with an eigen-based decomposition of the two ground components into a surface and a dihedral scattering contribution. Hence, this hybrid decomposition, which is based on [1,2], establishes an innovative way to retrieve soil moisture under vegetation. The developed inversion algorithm for soil moisture under vegetation cover is applied on fully polarimetric data of the TERENO campaign, conducted in May and June 2011 for the Rur catchment within the Eifel/Lower Rhine Valley Observatory. The fully polarimetric SAR data were acquired in high spatial resolution (range: 1.92m, azimuth: 0.6m) by DLR's novel F-SAR sensor at L-band. The inverted soil moisture product from the airborne SAR data is validated with corresponding distributed ground measurements for a quality assessment of the developed algorithm. The in situ measurements were obtained on the one hand by mobile FDR probes from agricultural fields near the towns of Merzenhausen and Selhausen incorporating different crop types and on the other hand by distributed wireless sensor networks (SoilNet clusters) from a grassland test site (near the town of Rollesbroich) and from a forest stand (within the Wüstebach sub-catchment). Each SoilNet cluster

  20. Some OFDM waveforms for a fully polarimetric weather radar

    NARCIS (Netherlands)

    Van Genderen, P.; Krasnov, O.A.; Wang, Z.; Tigrek, R.F.

    2012-01-01

    Retrieval of cloud parameters in weather radar benefits from polarimetric measurements. Most polarimetric radars measure the full backscatter matrix (BSM) using a few alternating polarized sounding signals. Using specially encoded orthogonal frequency division multiplexing (OFDM) signals however,

  1. Research on visible and near infrared spectral-polarimetric properties of soil polluted by crude oil

    Science.gov (United States)

    Shen, Hui-yan; Zhou, Pu-cheng; Pan, Bang-long

    2017-10-01

    Hydrocarbon contaminated soil can impose detrimental effects on forest health and quality of agricultural products. To manage such consequences, oil leak indicators should be detected quickly by monitoring systems. Remote sensing is one of the most suitable techniques for monitoring systems, especially for areas which are uninhabitable and difficulty to access. The most available physical quantities in optical remote sensing domain are the intensity and spectral information obtained by visible or infrared sensors. However, besides the intensity and wavelength, polarization is another primary physical quantity associated with an optical field. During the course of reflecting light-wave, the surface of soil polluted by crude oil will cause polarimetric properties which are related to the nature of itself. Thus, detection of the spectralpolarimetric properties for soil polluted by crude oil has become a new remote sensing monitoring method. In this paper, the multi-angle spectral-polarimetric instrument was used to obtain multi-angle visible and near infrared spectralpolarimetric characteristic data of soil polluted by crude oil. And then, the change rule between polarimetric properties with different affecting factors, such as viewing zenith angle, incidence zenith angle of the light source, relative azimuth angle, waveband of the detector as well as different grain size of soil were discussed, so as to provide a scientific basis for the research on polarization remote sensing for soil polluted by crude oil.

  2. Fabrication of a LRET-based upconverting hybrid nanocomposite for turn-on sensing of H2O2 and glucose

    Science.gov (United States)

    Wu, Shuang; Kong, Xiang-Juan; Cen, Yao; Yuan, Jing; Yu, Ru-Qin; Chu, Xia

    2016-04-01

    Blood glucose detecting has aroused considerable attention because diabetes mellitus has become a worldwide publish health problem. Herein, we construct an exceptionally simple upconverting hybrid nanocomposite, composed of DNA-templated Ag nanoparticles (DNA-AgNPs) and NaYF4:Yb/Tm@NaYF4 core-shell upconversion nanoparticles (UCNPs), for the sensing of H2O2 and glucose. In this design, UCNPs with bared surface act as the donor, and DNA-AgNPs serve as efficient quenchers. DNA-AgNPs can be directly assembled on the bared surface of UCNPs, which further decreases the distance of donor-to-acceptor. The formation of DNA-AgNPs/UCNP nanocomposite results in luminescence quenching of UCNP by DNA-AgNPs through luminescence resonance energy transfer (LRET). Upon H2O2 addition, AgNPs can be etched and transformed into Ag+, leading to inhibition of the LRET process and causing the recovery of upconversion luminescence. Based on the conversion of glucose into H2O2 by glucose oxidase, the DNA-AgNPs/UCNP nanocomposite can also be exploited for glucose sensing. Moreover, due to the non-autofluorescence offered by UCNPs, the approach developed can be applied to monitor glucose levels in human serum samples with satisfactory results.Blood glucose detecting has aroused considerable attention because diabetes mellitus has become a worldwide publish health problem. Herein, we construct an exceptionally simple upconverting hybrid nanocomposite, composed of DNA-templated Ag nanoparticles (DNA-AgNPs) and NaYF4:Yb/Tm@NaYF4 core-shell upconversion nanoparticles (UCNPs), for the sensing of H2O2 and glucose. In this design, UCNPs with bared surface act as the donor, and DNA-AgNPs serve as efficient quenchers. DNA-AgNPs can be directly assembled on the bared surface of UCNPs, which further decreases the distance of donor-to-acceptor. The formation of DNA-AgNPs/UCNP nanocomposite results in luminescence quenching of UCNP by DNA-AgNPs through luminescence resonance energy transfer (LRET). Upon H

  3. Polarimetric LIDAR with FRI sampling for target characterization

    Science.gov (United States)

    Wijerathna, Erandi; Creusere, Charles D.; Voelz, David; Castorena, Juan

    2017-09-01

    Polarimetric LIDAR is a significant tool for current remote sensing applications. In addition, measurement of the full waveform of the LIDAR echo provides improved ranging and target discrimination, although, data storage volume in this approach can be problematic. In the work presented here, we investigated the practical issues related to the implementation of a full waveform LIDAR system to identify polarization characteristics of multiple targets within the footprint of the illumination beam. This work was carried out on a laboratory LIDAR testbed that features a flexible arrangement of targets and the ability to change the target polarization characteristics. Targets with different retardance characteristics were illuminated with a linearly polarized laser beam and the return pulse intensities were analyzed by rotating a linear analyzer polarizer in front of a high-speed detector. Additionally, we explored the applicability and the limitations of applying a sparse sampling approach based on Finite Rate of Innovations (FRI) to compress and recover the characteristic parameters of the pulses reflected from the targets. The pulse parameter values extracted by the FRI analysis were accurate and we successfully distinguished the polarimetric characteristics and the range of multiple targets at different depths within the same beam footprint. We also demonstrated the recovery of an unknown target retardance value from the echoes by applying a Mueller matrix system model.

  4. Measurement of impulse current using polarimetric fiber optic sensor

    Science.gov (United States)

    Ginter, Mariusz

    2017-08-01

    In the paper the polarimetric current sensing solution used for measurements of high amplitude currents and short durations is presented. This type of sensor does not introduce additional resistance and inductance into the circuit, which is a desirable phenomenon in this type of measurement. The magneto element is a fiber optic coil made of spun fiber optic. The fiber in which the core is twisted around its axis is characterized by a small effect of interfering magnitudes, ie mechanical vibrations and pressure changes on the polarimeter. The presented polarimetric current sensor is completely fiber optic. Experimental results of a proposed sensor construction solution operating at 1550 nm and methods of elimination of influence values on the fiber optic current sensor were presented. The sensor was used to measure the impulse current. The generated current pulses are characterized by a duration of 23μs and amplitudes ranging from 1 to 3.5 kA. The currents in the discharge circuit are shown. The measurement uncertainty of the amplitude of the electric current in the range of measured impulses was determined and estimated to be no more than 2%.

  5. G0-WISHART Distribution Based Classification from Polarimetric SAR Images

    Science.gov (United States)

    Hu, G. C.; Zhao, Q. H.

    2017-09-01

    Enormous scientific and technical developments have been carried out to further improve the remote sensing for decades, particularly Polarimetric Synthetic Aperture Radar(PolSAR) technique, so classification method based on PolSAR images has getted much more attention from scholars and related department around the world. The multilook polarmetric G0-Wishart model is a more flexible model which describe homogeneous, heterogeneous and extremely heterogeneous regions in the image. Moreover, the polarmetric G0-Wishart distribution dose not include the modified Bessel function of the second kind. It is a kind of simple statistical distribution model with less parameter. To prove its feasibility, a process of classification has been tested with the full-polarized Synthetic Aperture Radar (SAR) image by the method. First, apply multilook polarimetric SAR data process and speckle filter to reduce speckle influence for classification result. Initially classify the image into sixteen classes by H/A/α decomposition. Using the ICM algorithm to classify feature based on the G0-Wshart distance. Qualitative and quantitative results show that the proposed method can classify polaimetric SAR data effectively and efficiently.

  6. Detection and Monitoring of Inundation with Polarimetric L-Band SAR

    Science.gov (United States)

    Chapman, B. D.; Celi, J. E.; Hamilton, S. K.; McDonald, K. C.

    2014-12-01

    It has been known for decades that at wavelengths L-band or longer, SAR is a sensitive indicator of inundation underneath forest canopies. The high resolution detection of below-canopy inundation is difficult to accomplish at regional to continental scales using other types of remote sensing sensors, making it a compelling SAR measurement especially useful for studying wetland inundation dynamics, particularly in difficult-to-reach access, canopy-covered tropical forest environments. Most results have utilized spaceborne SAR observations with less than fully polarimetric data. Since one of the objectives of the NISAR mission is to characterize and understand the fundamental process that drives changes to ecosystems such as wetland inundated areas, we will discuss the sensitivity of L-band SAR to inundation. We will illustrate the detection of inundation using fully polarimetric L-band SAR data from UAVSAR, NASA's airborne SAR, over a tropical forest region in Ecuador and Peru. At the same time as the data collection, measurements were made on the ground to characterize vegetation and inundation characteristics. The field data were used to validate the results of classifying the vanZyl decomposition of the polarimetric data. We compare this classification with that possible with a reduced subset of the polarimetric observations.

  7. Polarimetric SAR image classification based on discriminative dictionary learning model

    Science.gov (United States)

    Sang, Cheng Wei; Sun, Hong

    2018-03-01

    Polarimetric SAR (PolSAR) image classification is one of the important applications of PolSAR remote sensing. It is a difficult high-dimension nonlinear mapping problem, the sparse representations based on learning overcomplete dictionary have shown great potential to solve such problem. The overcomplete dictionary plays an important role in PolSAR image classification, however for PolSAR image complex scenes, features shared by different classes will weaken the discrimination of learned dictionary, so as to degrade classification performance. In this paper, we propose a novel overcomplete dictionary learning model to enhance the discrimination of dictionary. The learned overcomplete dictionary by the proposed model is more discriminative and very suitable for PolSAR classification.

  8. Tropical Mangrove Mapping Using Fully-Polarimetric Radar Data

    Directory of Open Access Journals (Sweden)

    Bambang Trisasongko

    2009-09-01

    Full Text Available Although mangrove is one of important ecosystems in the world, it has been abused and exploited by human for various purposes. Monitoring mangrove is therefore required to maintain a balance between economy and conservation and provides up-to-date information for rehabilitation. Optical remote sensing data have delivered such information, however ever-changing atmospheric disturbance may significantly decrease thematic content. In this research, Synthetic Aperture Radar (SAR fully polarimetric data were evaluated to present an alternative for mangrove mapping. Assessment using three statistical trees was performed on both tonal and textural data. It was noticeable that textural data delivered fairly good improvement which reduced the error rate to around 5-6% at L-band. This suggests that insertion of textural data is more important than any information derived from decomposition algorithm.

  9. Hierarchical 3-dimensional nickel-iron nanosheet arrays on carbon fiber paper as a novel electrode for non-enzymatic glucose sensing.

    Science.gov (United States)

    Kannan, Palanisamy; Maiyalagan, Thandavarayan; Marsili, Enrico; Ghosh, Srabanti; Niedziolka-Jönsson, Joanna; Jönsson-Niedziolka, Martin

    2016-01-14

    Three-dimensional nickel-iron (3-D/Ni-Fe) nanostructures are exciting candidates for various applications because they produce more reaction-active sites than 1-D and 2-D nanostructured materials and exhibit attractive optical, electrical and catalytic properties. In this work, freestanding 3-D/Ni-Fe interconnected hierarchical nanosheets, hierarchical nanospheres, and porous nanospheres are directly grown on a flexible carbon fiber paper (CFP) substrate by a single-step hydrothermal process. Among the nanostructures, 3-D/Ni-Fe interconnected hierarchical nanosheets show excellent electrochemical properties because of its high conductivity, large specific active surface area, and mesopores on its walls (vide infra). The 3-D/Ni-Fe hierarchical nanosheet array modified CFP substrate is further explored as a novel electrode for electrochemical non-enzymatic glucose sensor application. The 3-D/Ni-Fe hierarchical nanosheet arrays exhibit significant catalytic activity towards the electrochemical oxidation of glucose, as compared to the 3-D/Ni-Fe hierarchical nanospheres, and porous nanospheres. The 3-D/Ni-Fe hierarchical nanosheet arrays can access a large amount of glucose molecules on their surface (mesopore walls) for an efficient electrocatalytic oxidation process. Moreover, 3-D/Ni-Fe hierarchical nanosheet arrays showed higher sensitivity (7.90 μA μM(-1) cm(-2)) with wide linear glucose concentration ranging from 0.05 μM to 0.2 mM, and the low detection limit (LOD) of 0.031 μM (S/N = 3) is achieved by the amperometry method. Further, the 3-D/Ni-Fe hierarchical nanosheet array modified CFP electrode can be demonstrated to have excellent selectivity towards the detection of glucose in the presence of 500-fold excess of major important interferents. All these results indicate that 3-D/Ni-Fe hierarchical nanosheet arrays are promising candidates for non-enzymatic glucose sensing.

  10. Electrochemical quartz crystal impedance study on immobilization of glucose oxidase in a polymer grown from dopamine oxidation at an Au electrode for glucose sensing

    International Nuclear Information System (INIS)

    Li Mingrui; Deng Chunyan; Xie Qingji; Yang Yang; Yao Shouzhuo

    2006-01-01

    Glucose oxidase (GOD) was codeposited into a polymer grown from oxidation of dopamine (DA) at an Au electrode in a neutral phosphate aqueous solution for the first time. The electrochemical quartz crystal impedance analysis (EQCIA) method was used to monitor the GOD-immobilization process. Effects of concentrations of phosphate buffer, DA and GOD were investigated, and the optimal concentrations were found to be 20.0mM phosphate buffer (pH 7.0), 30.0mM DA and 5.00mgml -1 GOD. A glucose biosensor was thus constructed, and effects of various experimental parameters on the sensor performance, including applied potential, solution pH and electroactive interferents, were examined. At an optimal potential of 0.6V versus the KCl-saturated calomel electrode (SCE), the current response of the biosensor in the selected phosphate buffer (pH 7.0) was linear with the concentration of glucose from 0.05 to 9mM, with a lower detection limit of 3μM (S/N=3), short response time (within 15s) and good anti-interferent ability. The Michaelis constant (K m app ) was estimated to be 9.6mM. The biosensor exhibited good storage stability, i.e. 96% of its initial response was retained after 7-day storage in the selected phosphate buffer at 4deg. C, and even after another 3 weeks the biosensor retained 86% of its initial response. In addition, the enzymatic specific activity and enzymatic relative activity of the GOD immobilized in the polymer from dopamine oxidation (PFDO) were estimated from the EQCIA method to be 1.43kUg -1 and 3.7%, respectively, which were larger than the relevant values obtained experimentally using poly(o-aminophenol) and poly(N-methylpyrrole) matrices, suggesting that the PFDO is a better matrix to immobilize GOD

  11. The effects of thermal equilibrium and contrast in LWIR polarimetric images.

    Science.gov (United States)

    Tyo, J Scott; Ratliff, Bradley M; Boger, James K; Black, Wiley T; Bowers, David L; Fetrow, Matthew P

    2007-11-12

    Long-wave infrared (LWIR) polarimetric signatures provide the potential for day-night detection and identification of objects in remotely sensed imagery. The source of optical energy in the LWIR is usually due to thermal emission from the object in question, which makes the signature dependent primarily on the target and not on the external environment. In this paper we explore the impact of thermal equilibrium and the temperature of (unseen) background objects on LWIR polarimetric signatures. We demonstrate that an object can completely lose its polarization signature when it is in thermal equilibrium with its optical background, even if it has thermal contrast with the objects that appear behind it in the image.

  12. Polarimetric Exploration of Solar System Small Bodies: Search for Habitability

    Science.gov (United States)

    Yanamandra-Fisher, Padma A.

    2015-08-01

    The overarching goals for the remote sensing and robotic exploration of our solar system and exoplanetary systems are: (1) understanding the formation of planetary systems and their diversity; and (2) search for habitability. These goals can be realized with the inclusion of spectrophotopolarimetry as a complementary approach to standard techniques of imaging and spectroscopy. Since all objects have unique polarimetric signatures, like fingerprints, much can be learned about the scattering object. Although polarization, in general, is elliptical by nature, special cases such as linear and circular polarimetric signatures provide insight into the various types of scattering media and are valuable tools to be developed. Additionally, spectral dependence of polarization is important to separate the macroscopic (bulk) properties of the scattering medium from the microscopic (particulate) properties of the scattering medium. The search for habitability can benefit from spectrophotopolarimetry. While linear polarization of reflected light by solar system objects (planetary atmospheres, satellites, rings systems, comets, asteroids, dust, etc.) provides insight into the scattering characteristics of aerosols and hazes in atmospheres and surficial properties of atmosphereless objects, circular polarization and related chirality) or handedness, a property of molecules that exhibit mirror-image symmetry, similar to right and left hands) can serve as diagnostic of biological activity. All known life forms on earth are chiral and pre-dominantly left-handed. However, many of these applications suffer from lack of detailed observations, instrumentation, dedicated missions and numerical/retrieval methods. I will present a review of the field, with advances made in instrumentation, measurements and applications to prospective missions.

  13. Fabrication of a Microneedle/CNT Hierarchical Micro/Nano Surface Electrochemical Sensor and Its In-Vitro Glucose Sensing Characterization

    Directory of Open Access Journals (Sweden)

    Youngsam Yoon

    2013-12-01

    Full Text Available We report fabrication of a microneedle-based three-electrode integrated electrochemical sensor and in-vitro characterization of this sensor for glucose sensing applications. A piece of silicon was sequentially dry and wet etched to form a 15 × 15 array of tall (approximately 380 µm sharp silicon microneedles. Iron catalyst was deposited through a SU-8 shadow mask to form the working electrode and counter electrode. A multi-walled carbon nanotube forest was grown directly on the silicon microneedle array and platinum nano-particles were electrodeposited. Silver was deposited on the Si microneedle array through another shadow mask and chlorinated to form a Ag/AgCl reference electrode. The 3-electrode electrochemical sensor was tested for various glucose concentrations in the range of 3~20 mM in 0.01 M phosphate buffered saline (PBS solution. The sensor’s amperometric response to the glucose concentration is linear and its sensitivity was found to be 17.73 ± 3 μA/mM-cm2. This microneedle-based sensor has a potential to be used for painless diabetes testing applications.

  14. SMEX02 Aircraft Polarimetric Scanning Radiometer (PSR) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The Polarimetric Scanning Radiometer (PSR) is an airborne microwave imaging radiometer developed and operated by the National Oceanic and Atmospheric Administration...

  15. IHW COMET HALLEY POLARIMETRIC OBSERVATIONS, V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains the polarimetric results reported to the International Halley Watch (IHW) Photometry and Polarimetry Network (PPN) by the various...

  16. CAMEX-3 POLARIMETRIC SCANNING RADIOMETER (PSR) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Polarimetric Scanning Radiometer (PSR) is a versatile airborne microwave imaging radiometer developed by the Georgia Institute of Technology and the NOAA...

  17. Preliminary evaluation of optical glucose sensing in red cell concentrations using near-infrared diffuse-reflectance spectroscopy

    Science.gov (United States)

    Suzuki, Yusuke; Maruo, Katsuhiko; Zhang, Alice W.; Shimogaki, Kazushige; Ogawa, Hideto; Hirayama, Fumiya

    2012-01-01

    Bacterial contamination of blood products is one of the most frequent infectious complications of transfusion. Since glucose levels in blood supplies decrease as bacteria proliferate, it should be possible to detect the presence of bacterial contamination by measuring the glucose concentrations in the blood components. Hence this study is aimed to serve as a preliminary study for the nondestructive measurement of glucose level in transfusion blood. The glucose concentrations in red blood cell (RBC) samples were predicted using near-infrared diffuse-reflectance spectroscopy in the 1350 to 1850 nm wavelength region. Furthermore, the effects of donor, hematocrit level, and temperature variations among the RBC samples were observed. Results showed that the prediction performance of a dataset which contained samples that differed in all three parameters had a standard error of 29.3 mg/dL. Multiplicative scatter correction (MSC) preprocessing method was also found to be effective in minimizing the variations in scattering patterns created by various sample properties. The results suggest that the diffuse-reflectance spectroscopy may provide another avenue for the detection of bacterial contamination in red cell concentrations (RCC) products.

  18. The loss of Sirt1 in mouse pancreatic beta cells impairs insulin secretion by disrupting glucose sensing

    DEFF Research Database (Denmark)

    Luu, L; Dai, F F; Prentice, K J

    2013-01-01

    Sirtuin 1 (SIRT1) has emerged as a key metabolic regulator of glucose homeostasis and insulin secretion. Enhanced SIRT1 activity has been shown to be protective against diabetes, although the mechanisms remain largely unknown. The aim of this study was to determine how SIRT1 regulates insulin sec...

  19. Phosphomolybdic acid functionalized graphene loading copper nanoparticles modified electrodes for non-enzymatic electrochemical sensing of glucose

    International Nuclear Information System (INIS)

    Xu, Jiaoyan; Cao, Xiyue; Xia, Jianfei; Gong, Shida; Wang, Zonghua; Lu, Lin

    2016-01-01

    A sensitive non-enzymatic glucose electrochemical biosensor (Cu/PMo 12 -GR/GCE) was developed based on the combination of copper nanoparticles (CuNPs) and phosphomolybdic acid functionalized graphene (PMo 12 -GR). PMo 12 -GR films were modified on the surface of glassy carbon electrode (GCE) through electrostatic self-assembly with the aid of poly diallyl dimethyl ammonium chloride (PDDA). Then CuNPs were successfully decorated onto the PMo 12 -GR modified GCE through electrodeposition. The morphology of Cu/PMo 12 -GR/GCE was characterized by scanning electron microscope (SEM). Cyclic voltammetry (CV) and chronoamperometry were used to investigate the electrochemical performances of the biosensor. The results indicated that the modified electrode displayed a synergistic effect of PMo 12 -GR sheets and CuNPs towards the electro-oxidation of glucose in the alkaline solution. At the optimal detection potential of 0.50 V, the response towards glucose presented a linear response ranging from 0.10 μM to 1.0 mM with a detection limit of 3.0 × 10 −2  μM (S/N = 3). In addition, Cu/PMo 12 -GR/GCE possessed a high selectivity, good reproducibility, excellent stability and acceptable recovery, which indicating the potential application in clinical field. - Highlights: • Cu/PMo 12 -GR/GCE as a non-enzymatic glucose electrochemical sensor. • PMo 12 is efficient for the uniform growth of Cu-NPs and electron transport. • The sensor exhibits good sensitivity and specificity towards glucose.

  20. Phosphomolybdic acid functionalized graphene loading copper nanoparticles modified electrodes for non-enzymatic electrochemical sensing of glucose

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiaoyan; Cao, Xiyue [College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Xia, Jianfei, E-mail: xiajianfei@126.com [College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Gong, Shida [College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Wang, Zonghua, E-mail: wangzonghua@qdu.edu.cn [College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Lu, Lin [College of Chemistry and Chemical Engineering, Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Collaborative Innovation Center for Marine Biomass Fiber Materials and Textiles, Laboratory of Fiber Materials and Modern Textile, The Growing Base for State Key Laboratory, Qingdao University, Qingdao 266071 (China); Zibo Normal College, Zibo, Shandong 255100 (China)

    2016-08-31

    A sensitive non-enzymatic glucose electrochemical biosensor (Cu/PMo{sub 12}-GR/GCE) was developed based on the combination of copper nanoparticles (CuNPs) and phosphomolybdic acid functionalized graphene (PMo{sub 12}-GR). PMo{sub 12}-GR films were modified on the surface of glassy carbon electrode (GCE) through electrostatic self-assembly with the aid of poly diallyl dimethyl ammonium chloride (PDDA). Then CuNPs were successfully decorated onto the PMo{sub 12}-GR modified GCE through electrodeposition. The morphology of Cu/PMo{sub 12}-GR/GCE was characterized by scanning electron microscope (SEM). Cyclic voltammetry (CV) and chronoamperometry were used to investigate the electrochemical performances of the biosensor. The results indicated that the modified electrode displayed a synergistic effect of PMo{sub 12}-GR sheets and CuNPs towards the electro-oxidation of glucose in the alkaline solution. At the optimal detection potential of 0.50 V, the response towards glucose presented a linear response ranging from 0.10 μM to 1.0 mM with a detection limit of 3.0 × 10{sup −2} μM (S/N = 3). In addition, Cu/PMo{sub 12}-GR/GCE possessed a high selectivity, good reproducibility, excellent stability and acceptable recovery, which indicating the potential application in clinical field. - Highlights: • Cu/PMo{sub 12}-GR/GCE as a non-enzymatic glucose electrochemical sensor. • PMo{sub 12} is efficient for the uniform growth of Cu-NPs and electron transport. • The sensor exhibits good sensitivity and specificity towards glucose.

  1. Polarimetric studies of polyethylene terephtalate flexible substrates

    Science.gov (United States)

    Stchakovsky, M.; Garcia-Caurel, E.; Warenghem, M.

    2008-12-01

    Polymer sheets are currently used worldwide in a wide range of applications. The manufacturing process of these sheets involves extruding machines that stretch the material in both lateral and longitudinal directions with respect to the machine direction, thus inducing birefringence. In most cases, the film obtained is optically biaxial. Polarimetric spectroscopy (Ellipsometry and Mueller Matrix) combined with conoscopic observation are the methods of choice to study these properties. In this work we report an analysis of commercially available polyethylene terephtalate (PET) films used as substrate for food packaging as well as for embedded electronic devices such as solar cells or flexible displays. Initial observation of these films through polarizing microscope in conoscopic mode reveals first the trace of optical axis plane with respect to the film surface and second, whether the optical axis is acute or not. This preliminary study allows optimal sample positioning for further polarimetric studies. The measurements and modelling are done in both reflection and transmission mode on several spectroscopic polarimetric setups from UV to NIR. The models give as a main result, the dielectric tensor of the film as well as its orientation with respect to the laboratory reference frame.

  2. Polarimetric Signatures from a Crop Covered Land Surface Measured by an L-band Polarimetric Radiometer

    DEFF Research Database (Denmark)

    Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    This paper describes preliminary results from field measurements of polarimetric azimuth signatures with the EMIRAD L-band polarimetric radiometer, performed over a land test site at the Institut National de la Recherche Agronomique in Avignon, France. Scans of 180 degrees in azimuth were carried...... out in order to identify an eventual dependence of the Stokes vector on the look-direction. Results indicate a clear signature, for bare soil as well as for the crop-covered surface, and variations of more than 10 K are observed....

  3. Segmentation of Polarimetric SAR Images Usig Wavelet Transformation and Texture Features

    Science.gov (United States)

    Rezaeian, A.; Homayouni, S.; Safari, A.

    2015-12-01

    Polarimetric Synthetic Aperture Radar (PolSAR) sensors can collect useful observations from earth's surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR) are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT). Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM) and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  4. SEGMENTATION OF POLARIMETRIC SAR IMAGES USIG WAVELET TRANSFORMATION AND TEXTURE FEATURES

    Directory of Open Access Journals (Sweden)

    A. Rezaeian

    2015-12-01

    Full Text Available Polarimetric Synthetic Aperture Radar (PolSAR sensors can collect useful observations from earth’s surfaces and phenomena for various remote sensing applications, such as land cover mapping, change and target detection. These data can be acquired without the limitations of weather conditions, sun illumination and dust particles. As result, SAR images, and in particular Polarimetric SAR (PolSAR are powerful tools for various environmental applications. Unlike the optical images, SAR images suffer from the unavoidable speckle, which causes the segmentation of this data difficult. In this paper, we use the wavelet transformation for segmentation of PolSAR images. Our proposed method is based on the multi-resolution analysis of texture features is based on wavelet transformation. Here, we use the information of gray level value and the information of texture. First, we produce coherency or covariance matrices and then generate span image from them. In the next step of proposed method is texture feature extraction from sub-bands is generated from discrete wavelet transform (DWT. Finally, PolSAR image are segmented using clustering methods as fuzzy c-means (FCM and k-means clustering. We have applied the proposed methodology to full polarimetric SAR images acquired by the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR L-band system, during July, in 2012 over an agricultural area in Winnipeg, Canada.

  5. Microwave Deposition of Palladium Catalysts on Graphite Spheres and Reduced Graphene Oxide Sheets for Electrochemical Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Jian-De Xie

    2017-09-01

    Full Text Available This work outlines a synthetic strategy inducing the microwave-assisted synthesis of palladium (Pd nanocrystals on a graphite sphere (GS and reduced graphene oxide (rGO supports, forming the Pd catalysts for non-enzymatic glucose oxidation reaction (GOR. The pulse microwave approach takes a short period (i.e., 10 min to fast synthesize Pd nanocrystals onto a carbon support at 150 °C. The selection of carbon support plays a crucial role in affecting Pd particle size and dispersion uniformity. The robust design of Pd-rGO catalyst electrode displays an enhanced electrocatalytic activity and sensitivity toward GOR. The enhanced performance is mainly attributed to the synergetic effect that combines small crystalline size and two-dimensional conductive support, imparting high accessibility to non-enzymatic GOR. The rGO sheets serve as a conductive scaffold, capable of fast conducting electron. The linear plot of current response versus glucose concentration exhibits good correlations within the range of 1–12 mM. The sensitivity of the Pd-rGO catalyst is significantly enhanced by 3.7 times, as compared to the Pd-GS catalyst. Accordingly, the Pd-rGO catalyst electrode can be considered as a potential candidate for non-enzymatic glucose biosensor.

  6. Polarimetric Edge Detector Based on the Complex Wishart Distribution

    DEFF Research Database (Denmark)

    Skriver, Henning; Schou, Jesper; Nielsen, Allan Aasbjerg

    2001-01-01

    A new edge detector for polarimetric SAR data has been developed. The edge detector is based on a newly developed test statistic for equality of two complex covariance matrices following the complex Wishart distribution and an associated asymptotic probability for the test statistic. The new...... for the full polarimetric detector compared to single channel approaches....

  7. Masses of Negative Multinomial Distributions: Application to Polarimetric Image Processing

    Directory of Open Access Journals (Sweden)

    Philippe Bernardoff

    2013-01-01

    Full Text Available This paper derives new closed-form expressions for the masses of negative multinomial distributions. These masses can be maximized to determine the maximum likelihood estimator of its unknown parameters. An application to polarimetric image processing is investigated. We study the maximum likelihood estimators of the polarization degree of polarimetric images using different combinations of images.

  8. Target detection with polarimetric C-band SAR

    NARCIS (Netherlands)

    Broek, A.C. van den; Dekker, R.J.; Smith, A.J.E.; Vries, F.P.P. de

    1999-01-01

    We have studied an optimal target detection procedure for polarimetric SAR data by using PHARUS data collected during the MIMEX campaign. The detection method is especially suitable when no a priory knowledge of the target is available. We have found that polarimetric whitening filtering preceding

  9. Sensing interstitial glucose to nudge active lifestyles (SIGNAL): feasibility of combining novel self-monitoring technologies for persuasive behaviour change.

    Science.gov (United States)

    Whelan, Maxine E; Kingsnorth, Andrew P; Orme, Mark W; Sherar, Lauren B; Esliger, Dale W

    2017-10-08

    Increasing physical activity (PA) reduces the risk of developing diabetes, highlighting the role of preventive medicine approaches. Changing lifestyle behaviours is difficult and is often predicated on the assumption that individuals are willing to change their lifestyles today to reduce the risk of developing disease years or even decades later. The self-monitoring technologies tested in this study will present PA feedback in real time, parallel with acute physiological data. Presenting the immediate health benefits of being more physically active may help enact change by observing the immediate consequences of that behaviour. The present study aims to assess user engagement with the self-monitoring technologies in individuals at moderate-to-high risk of developing type 2 diabetes. 45 individuals with a moderate-to-high risk, aged ≥40 years old and using a compatible smartphone, will be invited to take part in a 7-week protocol. Following 1 week of baseline measurements, participants will be randomised into one of three groups: group 1- glucose feedback followed by biobehavioural feedback (glucose plus PA); group 2-PA feedback followed by biobehavioural feedback; group 3-biobehavioural feedback. A PA monitor and a flash glucose monitor will be deployed during the intervention. Participants will wear both devices throughout the intervention but blinded to feedback depending on group allocation. The primary outcome is the level of participant engagement and will be assessed by device use and smartphone usage. Feasibility will be assessed by the practicality of the technology and screening for diabetes risk. Semistructured interviews will be conducted to explore participant experiences using the technologies. ISRCTN17545949. Registered on 15/05/2017. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  10. The CASLEO Polarimetric Survey of Main Belt Asteroids: Updated results

    Science.gov (United States)

    Gil-Hutton, R.; Cellino, A.; Cañada-Assandri, M.

    2011-10-01

    We present updated results of the polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina, using the 2.15 m telescope and the Torino and CASPROF polarimeters. The goals of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids belonging to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. The survey began in 2003, and data for a sample of more than 170 asteroids have been obtained, most of them having been polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for several taxonomic classes.

  11. Polarimetric scattering and SAR information retrieval

    CERN Document Server

    Jin, Ya-Qiu

    2013-01-01

    Taking an innovative look at Synthetic Aperture Radar (SAR), this practical reference fully covers new developments in SAR and its various methodologies and enables readers to interpret SAR imagery An essential reference on polarimetric Synthetic Aperture Radar (SAR), this book uses scattering theory and radiative transfer theory as a basis for its treatment of topics. It is organized to include theoretical scattering models and SAR data analysis techniques, and presents cutting-edge research on theoretical modelling of terrain surface. The book includes quantitative app

  12. Passive Polarimetric Remote Sensing of Snow and Ice

    Science.gov (United States)

    1997-09-30

    ice and snow, we proposed to measure the Stokes parameters, as a function of incidence angle, for growing ice, desalinated ice, new snow, and...orientation of ice crystals, brine channels and air pockets. Although the CRREL facility is well equipped to artificially generate ice (via refrigeration of...calibration and early growth phase of new ice (See figure 2) 26-Feb Growth phase of new ice 26-Feb Old, desalinated ice (See figure 3) Slight surface

  13. Polarimetric and Indoor Imaging Fusion Based on Compressive Sensing

    Science.gov (United States)

    2013-04-01

    handle complex arithmetic [33]. Equations (13, 14) represent one strategy that can be adopted for sparsity-based change detection approach, wherein...Pierri, "A simple strategy to detect changes in through the wall imaging," Progress in Electromagnetics Research M, vol. 7, pp. 1-13,2009. [16] J...beamspace MUSIC ," IEEE Trans, on Antennas and Propagation, vol. 56, no. 6, pp. 1763- 1774, Jun. 2008. [41] Y-S. Yoon, M. G. Amin, and F. Ahmad

  14. Comprehensive Space-Object Characterization using Spectrally Compressive Polarimetric Sensing

    Science.gov (United States)

    2015-04-08

    PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Contracts and Grants Accounting, Main 1 University of New Mexico , MSC01 1245 Albuquerque, NM 87131...AFRL-OSR-VA-TR-2015-0100 Comprehensive Space-Object Characterization Sudhakar Prasad UNIVERSITY OF NEW MEXICO Final Report 04/17/2015 DISTRIBUTION A...8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) Air Force Office of Scientific Research 875 N

  15. Imaging and Non-Imaging Polarimetric Methods for Remote Sensing

    Science.gov (United States)

    2016-02-09

    means of processing polarization data. In this project, the DRM has been expanded to include a full functional formalism, allowing for a range of...this project, the DRM has been expanded to include a full functional formalism, allowing for a range of new tools in polarimeter design to be brought...matrix W−1 is generally referred to as the data reduction matrix ( DRM ).28 While the above discussion approaches the problem from a linear algebra

  16. Characterization and performance of a LWIR polarimetric imager

    Science.gov (United States)

    Eriksson, Johan; Bergström, David; Renhorn, Ingmar

    2017-10-01

    Polarimetric information has been shown to provide means for potentially enhancing the capacity of electro-optical sensors in areas such as target detection, recognition and identification. The potential benefit must be weighed against the added complexity of the sensor and the occurrence and robustness of polarimetric signatures. While progress in the design of novel systems for snapshot polarimetry may result in compact and lightweight polarimetric sensors, the aim of this work is to report on the design, characterization and performance of a polarimetric imager, primarily designed for polarimetric signature assessment of static scenes in the long wave thermal infrared. The system utilizes the division-of-time principle and is based on an uncooled microbolometer camera and a rotating polarizing filter. Methods for radiometric and polarimetric calibrations are discussed. A significant intrinsic polarization dependency of the microbolometer camera is demonstrated and it is shown that the ability to characterize, model and compensate for various instrument effects play a crucial role for polarimetric signature assessment.

  17. Feature-Based Nonlocal Polarimetric SAR Filtering

    Directory of Open Access Journals (Sweden)

    Xiaoli Xing

    2017-10-01

    Full Text Available Polarimetric synthetic aperture radar (PolSAR images are inherently contaminated by multiplicative speckle noise, which complicates the image interpretation and image analyses. To reduce the speckle effect, several adaptive speckle filters have been developed based on the weighted average of the similarity measures commonly depending on the model or probability distribution, which are often affected by the distribution parameters and modeling texture components. In this paper, a novel filtering method introduces the coefficient of variance ( CV and Pauli basis (PB to measure the similarity, and the two features are combined with the framework of the nonlocal mean filtering. The CV is used to describe the complexity of various scenes and distinguish the scene heterogeneity; moreover, the Pauli basis is able to express the polarimetric information in PolSAR image processing. This proposed filtering combines the CV and Pauli basis to improve the estimation accuracy of the similarity weights. Then, the similarity of the features is deduced according to the test statistic. Subsequently, the filtering is proceeded by using the nonlocal weighted estimation. The performance of the proposed filter is tested with the simulated images and real PolSAR images, which are acquired by AIRSAR system and ESAR system. The qualitative and quantitative experiments indicate the validity of the proposed method by comparing with the widely-used despeckling methods.

  18. Evaluation of the Wishart test statistics for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2003-01-01

    A test statistic for equality of two covariance matrices following the complex Wishart distribution has previously been used in new algorithms for change detection, edge detection and segmentation in polarimetric SAR images. Previously, the results for change detection and edge detection have been...... quantitatively evaluated. This paper deals with the evaluation of segmentation. A segmentation performance measure originally developed for single-channel SAR images has been extended to polarimetric SAR images, and used to evaluate segmentation for a merge-using-moment algorithm for polarimetric SAR data....

  19. C- and L-band multi-temporal polarimetric signatures of crops

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Flemming; Thomsen, Anton

    1996-01-01

    Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric SAR (EMISAR) during a number of missions at the Danish test site Foulum during 1994 and 1995. EMISAR has operated in a fully polarimetric mode at C-band since the fall of 1993 and at L-band since the beginn......Polarimetric SAR-data of agricultural fields have been acquired by the Danish polarimetric SAR (EMISAR) during a number of missions at the Danish test site Foulum during 1994 and 1995. EMISAR has operated in a fully polarimetric mode at C-band since the fall of 1993 and at L-band since...... the beginning of 1995. The SAR system is installed on a Danish Air Force Gulfstream aircraft, and a significant amount of polarimetric SAR data have been acquired on various missions. Polarimetric parameters for a number of different agricultural crops are shown, and the advantage of having polarimetric, multi...

  20. Nonlinear Polarimetric Microscopy for Biomedical Imaging

    Science.gov (United States)

    Samim, Masood

    A framework for the nonlinear optical polarimetry and polarimetric microscopy is developed. Mathematical equations are derived in terms of linear and nonlinear Stokes Mueller formalism, which comprehensively characterize the polarization properties of the incoming and outgoing radiations, and provide structural information about the organization of the investigated materials. The algebraic formalism developed in this thesis simplifies many predictions for a nonlinear polarimetry study and provides an intuitive understanding of various polarization properties for radiations and the intervening medium. For polarimetric microscopy experiments, a custom fast-scanning differential polarization microscope is developed, which is also capable of real-time three-dimensional imaging. The setup is equipped with a pair of high-speed resonant and galvanometric scanning mirrors, and supplemented by advanced adaptive optics and data acquisition modules. The scanning mirrors when combined with the adaptive optics deformable mirror enable fast 3D imaging. Deformable membrane mirrors and genetic algorithm optimization routines are employed to improve the imaging conditions including correcting the optical aberrations, maximizing signal intensities, and minimizing point-spread-functions of the focal volume. A field-programmable-gate array (FPGA) chip is exploited to rapidly acquire and process the multidimensional data. Using the nonlinear optical polarimetry framework and the home-built polarization microscope, a few biologically important tissues are measured and analyzed to gain insight as to their structure and dynamics. The structure and distribution of muscle sarcomere myosins, connective tissue collagen, carbohydrate-rich starch, and fruit fly eye retinal molecules are characterized with revealing polarization studies. In each case, using the theoretical framework, polarization sensitive data are analyzed to decipher the molecular orientations and nonlinear optical

  1. CLPX-Airborne: Polarimetric Ku-Band Scatterometer (POLSCAT) Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Ku-band polarimetric scatterometer (POLSCAT) data collected as part of the Cold Land Processes Field Experiment (CLPX) to enable the...

  2. Change detection in polarimetric SAR data over several time points

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Skriver, Henning

    2014-01-01

    A test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution is introduced. The test statistic is applied successfully to detect change in C-band EMISAR polarimetric SAR data over four time points....

  3. NAMMA NASA POLARIMETRIC DOPPLER WEATHER RADAR (NPOL) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Polarimetric Radar (NPOL), developed by a research team from Wallops Flight Facility, is a fully transportable and self-contained S-band research radar that...

  4. CLPX-Airborne: Multiband Polarimetric Scanning Radiometer (PSR) Imagery

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides multiband polarimetric brightness temperature images over three 25 x 25 km Meso-cell Study Areas (MSAs) in Northern Colorado. The purpose of...

  5. NAMMA NASA POLARIMETRIC DOPPLER WEATHER RADAR (NPOL) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The NAMMA NASA Polarimetric Doppler Weather Radar (NPOL) dataset used the NPOL, developed by a research team from Wallops Flight Facility, is a fully transportable...

  6. Digital Beamforming Synthetic Aperture Radar (DBSAR) Polarimetric Upgrade

    Science.gov (United States)

    Rincon, Rafael F.; Perrine, Martin; McLinden, Matthew; Valett, Susan

    2011-01-01

    The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art radar system developed at NASA/Goddard Space Flight Center for the development and implementation of digital beamforming radar techniques. DBSAR was recently upgraded to polarimetric operation in order to enhance its capability as a science instrument. Two polarimetric approaches were carried out which will be demonstrated in upcoming flight campaigns.

  7. Pulse-based internal calibration of polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Skou, Niels; Christensen, Erik Lintz

    1994-01-01

    Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops and devel......Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops...

  8. Polarimetric Coherence Optimization for Multibaseline SAR Data

    Science.gov (United States)

    Neumann, M.; Ferro-Famil, L.; Reigber, A.

    2007-03-01

    This paper analyzes different approaches for polarimetric optimization of multibaseline interferometric coherences. Two general methods are developed which simultaneously optimize coherences for more than two datasets. The first method is based on multiset canonical correlation analysis, and it provides every dataset with a distinguished dominant scattering mechanism. The second optimization method is constrained to the use of an identical scattering mechanism for every dataset. A framework for a multibaseline orthogonal optimal scattering mechanisms decomposition is presented. The both methods are evaluated on real data acquired by DLR's ESAR sensor at L-band. As experimental results indicate, preferring simultaneous multibaseline coherence optimization to single-baseline optimization improves the estimation of the dominant scattering mechanisms and their interferometric phases.

  9. Polarimetric ISAR: Simulation and image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, David H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-03-21

    In polarimetric ISAR the illumination platform, typically airborne, carries a pair of antennas that are directed toward a fixed point on the surface as the platform moves. During platform motion, the antennas maintain their gaze on the point, creating an effective aperture for imaging any targets near that point. The interaction between the transmitted fields and targets (e.g. ships) is complicated since the targets are typically many wavelengths in size. Calculation of the field scattered from the target typically requires solving Maxwell’s equations on a large three-dimensional numerical grid. This is prohibitive to use in any real-world imaging algorithm, so the scattering process is typically simplified by assuming the target consists of a cloud of independent, non-interacting, scattering points (centers). Imaging algorithms based on this scattering model perform well in many applications. Since polarimetric radar is not very common, the scattering model is often derived for a scalar field (single polarization) where the individual scatterers are assumed to be small spheres. However, when polarization is important, we must generalize the model to explicitly account for the vector nature of the electromagnetic fields and its interaction with objects. In this note, we present a scattering model that explicitly includes the vector nature of the fields but retains the assumption that the individual scatterers are small. The response of the scatterers is described by electric and magnetic dipole moments induced by the incident fields. We show that the received voltages in the antennas are linearly related to the transmitting currents through a scattering impedance matrix that depends on the overall geometry of the problem and the nature of the scatterers.

  10. Moving towards more intuitive display strategies for polarimetric image data

    Science.gov (United States)

    Ratliff, Bradley M.; Tyo, J. Scott

    2017-09-01

    The display of polarimetric imaging data has been a subject of considerable debate. Display strategies range from direct display of the Stokes vector images (or their derivatives) to false color representations. In many cases, direct interpretation of polarimetric image data using traditional display strategies is not intuitive and can at times result in confusion as to what benefit polarimetric information is actually providing. Here we investigate approaches that attempt to augment the s0 image with polarimetric information, rather than directly display it, as a means of enhancing the baseband s0 image. The benefit is that the polarization-enhanced visible or infrared image maintains a familiar look without the need for complex interpretation of the meaning of the polarimetric data, thus keeping the incorporation of polarimetric information transparent to the end user. The method can be applied to monochromatic or multi-band data, which allows color to be used for representing spectral data in multi- or hyper-spectropolarimetric applications. We take a more subjective approach to image enhancement than current techniques employ by simply seeking to improve contrast and shape information for polarized objects within a scene. We find that such approaches provide clear enhancement to the imagery when polarized objects are contained within the scene without the need for complex interpretation of polarization phenomenology.

  11. Polarimetric survey of main-belt asteroids. V. The unusual polarimetric behavior of V-type asteroids

    Science.gov (United States)

    Gil-Hutton, R.; López-Sisterna, C.; Calandra, M. F.

    2017-03-01

    Aims: We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the CASPROF and CASPOL polarimeters at the 2.15 m telescope. The CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation and CASPOL is a polarimeter based on a CCD detector, which allows us to observe fainter objects with better signal-to-noise ratio. Results: The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We obtained 55 polarimetric measurements for 28 V-type main belt asteroids, all of them polarimetrically observed for the first time. The data obtained in this survey let us find polarimetric parameters for (1459) Magnya and for a group of 11 small V-type objects with similar polarimetric behavior. These polarization curves are unusual since they show a shallow minimum and a small inversion angle in comparison with (4) Vesta, although they have a steeper slope at α0. This polarimetric behavior could be explained by differences in the regoliths of these asteroids. The observations of (2579) Spartacus, and perhaps also (3944) Halliday, indicate a inversion angle larger than 24-25°. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  12. Laboratory Measurements of Single-Particle Polarimetric Spectrum

    Science.gov (United States)

    Gritsevich, M.; Penttila, A.; Maconi, G.; Kassamakov, I.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

    2017-12-01

    Measuring scattering properties of different targets is important for material characterization, remote sensing applications, and for verifying theoretical results. Furthermore, there are usually simplifications made when we model targets and compute the scattering properties, e.g., ideal shape or constant optical parameters throughout the target material. Experimental studies help in understanding the link between the observed properties and computed results. Experimentally derived Mueller matrices of studied particles can be used as input for larger-scale scattering simulations, e.g., radiative transfer computations. This method allows to bypass the problem of using an idealized model for single-particle optical properties. While existing approaches offer ensemble- and orientation-averaged particle properties, our aim is to measure individual particles with controlled or known orientation. With the newly developed scatterometer, we aim to offer novel possibility to measure single, small (down to μm-scale) targets and their polarimetric spectra. This work presents an experimental setup that measures light scattered by a fixed small particle with dimensions ranging between micrometer and millimeter sizes. The goal of our setup is nondestructive characterization of such particles by measuring light of multiple wavelengths scattered in 360° in a horizontal plane by an ultrasonically levitating sample, whilst simultaneously controlling its 3D position and orientation. We describe the principles and design of our instrument and its calibration. We also present example measurements of real samples. This study was conducted under the support from the European Research Council, in the frame of the Advanced Grant project No. 320773 `Scattering and Absorption of Electromagnetic Waves in Particulate Media' (SAEMPL).

  13. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 Mobile X-Band Polarimetric Weather Radar dataset was collected by the Mobile X-band Polarimetric Weather Radar on Wheels (X-POW), which is a Doppler...

  14. Multi-Temporal Polarimetric RADARSAT-2 for Land Cover Monitoring in Northeastern Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Jeffrey W. Cable

    2014-03-01

    Full Text Available For successful applications of microwave remote sensing endeavors it is essential to understand how surface targets respond to changing synthetic aperture radar (SAR parameters. The purpose of the study is to examine how two particular parameters, acquisition time and incidence angle, influences the response from various land use/land cover types (forests, urban infrastructure, surface water and marsh wetland targets using nine RADARSAT-2 C-band fine-beam (FQ7 and FQ21 fully polarimetric SAR data acquired during the 2011 growing season over northern Ontario, Canada. The results indicate that backscatter from steep incidence angle acquisitions was typically higher than shallow angles. Wetlands showed an increase in HH and HV intensity due to the growth of emergent vegetation over the course of the summer. The forest and urban targets displayed little variation in backscatter over time. The surface water target showed the greatest difference with respect to incidence angle, but was also determined to be the most affected by wind conditions. Analysis of the co-polarized phase difference revealed the urban target as greatly influenced by the incidence angle. The observed phase differences of the wetland target for all acquisitions also suggested evidence of double-bounce interactions, while the forest and surface water targets showed little to no phase difference. In addition, Cloude-Pottier and Freeman-Durden decompositions, when analyzed in conjunction with polarimetric response plots, provided supporting information to confidently identify the various targets and their scattering mechanisms.

  15. Polarimetric C-Band SAR Observations of Sea Ice in the Greenland Sea

    DEFF Research Database (Denmark)

    Thomsen, Bjørn Bavnehøj; Nghiem, S.V.; Kwok, R.

    1998-01-01

    The fully polarimetric EMISAR acquired C-band radar signatures of sea ice in the Greenland Sea during a campaign in March 1995. The authors present maps of polarimetric signatures over an area containing various kinds of ice and discuss the use of polarimetric SAR for identification of ice types...

  16. Initial assessment of an airborne Ku-band polarimetric SAR.

    Energy Technology Data Exchange (ETDEWEB)

    Raynal, Ann Marie; Doerry, Armin Walter

    2013-02-01

    Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.

  17. Knowledge-based sea ice classification by polarimetric SAR

    DEFF Research Database (Denmark)

    Skriver, Henning; Dierking, Wolfgang

    2004-01-01

    Polarimetric SAR images acquired at C- and L-band over sea ice in the Greenland Sea, Baltic Sea, and Beaufort Sea have been analysed with respect to their potential for ice type classification. The polarimetric data were gathered by the Danish EMISAR and the US AIRSAR which both are airborne...... systems. A hierarchical classification scheme was chosen for sea ice because our knowledge about magnitudes, variations, and dependences of sea ice signatures can be directly considered. The optimal sequence of classification rules and the rules themselves depend on the ice conditions/regimes. The use...... of the polarimetric phase information improves the classification only in the case of thin ice types but is not necessary for thicker ice (above about 30 cm thickness)...

  18. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning

    2004-01-01

    depths. The validity of the scattering models is examined using L-band polarimetric interferometric SAR data acquired with the EMISAR system over an ice cap located in the percolation zone of the Greenland ice sheet. Radar reflectors were deployed on the ice surface prior to the data acquisition in order......This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...... scattering models are similar to the oriented-volume model and the random-volume-over-ground model used in vegetation studies, but the ice models are adapted to the different geometry of land ice. Also, due to compaction, land ice is not uniform; a fact that must be taken into account for large penetration...

  19. Radar Measurement of Human Polarimetric Micro-Doppler

    Directory of Open Access Journals (Sweden)

    David Tahmoush

    2013-01-01

    Full Text Available We use polarimetric micro-Doppler for the detection of arm motion, especially for the classification of whether someone has their arms swinging and is thus unloaded. The arm is often bent at the elbow, providing a surface somewhat similar to a dihedral. This is distinct from the more planar surfaces of the body which allows us to isolate the signals of the arm (and knee. The dihedral produces a double bounce that can be seen in polarimetric radar data by measuring the phase difference between HH and VV. This measurement can then be used to determine whether the subject is unloaded.

  20. Compact polarimetric SAR product and calibration considerations for target analysis

    Science.gov (United States)

    Sabry, Ramin

    2016-10-01

    Compact polarimetric (CP) data exploitation is currently of growing interest considering the new generation of such Synthetic Aperture Radar (SAR) systems. These systems offer target detection and classification capabilities comparable to those of polarimetric SARs (PolSAR) with less stringent requirements. A good example is the RADARSAT Constellation Mission (RCM). In this paper, some characteristic CP products are described and effects of CP mode deviation from ideal circular polarization transmit on classifications are modeled. The latter is important for operation of typical CP modes (e.g., RCM). The developed model can be used to estimate the ellipticity variation from CP measured data, and hence, calibrate the classification products.

  1. Authentication of gold nanoparticle encoded pharmaceutical tablets using polarimetric signatures.

    Science.gov (United States)

    Carnicer, Artur; Arteaga, Oriol; Suñé-Negre, Josep M; Javidi, Bahram

    2016-10-01

    The counterfeiting of pharmaceutical products represents concerns for both industry and the safety of the general public. Falsification produces losses to companies and poses health risks for patients. In order to detect fake pharmaceutical tablets, we propose producing film-coated tablets with gold nanoparticle encoding. These coated tablets contain unique polarimetric signatures. We present experiments to show that ellipsometric optical techniques, in combination with machine learning algorithms, can be used to distinguish genuine and fake samples. To the best of our knowledge, this is the first report using gold nanoparticles encoded with optical polarimetric classifiers to prevent the counterfeiting of pharmaceutical products.

  2. POLARIMETRIC OBSERVATIONS OF {sigma} ORIONIS E

    Energy Technology Data Exchange (ETDEWEB)

    Carciofi, A. C.; Faes, D. M. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Townsend, R. H. D. [Department of Astronomy, University of Wisconsin-Madison, Sterling Hall, 475 N. Charter Street, Madison, WI 53706 (United States); Bjorkman, J. E., E-mail: carciofi@usp.br [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States)

    2013-03-20

    Some massive stars possess strong magnetic fields that confine plasma in the circumstellar environment. These magnetospheres have been studied spectroscopically, photometrically, and, more recently, interferometrically. Here we report on the first firm detection of a magnetosphere in continuum linear polarization, as a result of monitoring {sigma} Ori E at the Pico dos Dias Observatory. The non-zero intrinsic polarization indicates an asymmetric structure whose minor elongation axis is oriented 150. Degree-Sign 0 east of the celestial north. A modulation of the polarization was observed with a period of half of the rotation period, which supports the theoretical prediction of the presence of two diametrally opposed, corotating blobs of gas. A phase lag of -0.085 was detected between the polarization minimum and the primary minimum of the light curve, suggestive of a complex shape of the plasma clouds. We present a preliminary analysis of the data with the Rigidly Rotating Magnetosphere model, which could not reproduce simultaneously the photometric and polarimetric data. A toy model comprising two spherical corotating blobs joined by a thin disk proved more successful in reproducing the polarization modulation. With this model we were able to determine that the total scattering mass of the thin disk is similar to the mass of the blobs (2M{sub b}/M{sub d} = 1.2) and that the blobs are rotating counterclockwise on the plane of the sky. This result shows that polarimetry can provide a diagnostic of the geometry of clouds, which will serve as an important constraint for improving the Rigidly Rotating Magnetosphere model.

  3. EMISAR: An Absolutely Calibrated Polarimetric L- and C-band SAR

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Skou, Niels; Dall, Jørgen

    1998-01-01

    and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry. Thermal control and several calibration loops have been built into the system to ensure system stability and absolute......EMISAR is a high-resolution (2×2 m), fully polarimetric, dual-frequency (L- and C-band) synthetic aperture radar (SAR) system designed for remote-sensing applications. The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes...... calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key to most of the current applications. Recent interferometric enhancements are important for many scientific applications...

  4. Retrieval of Macro- and Micro-Physical Properties of Oceanic Hydrosols from Polarimetric Observations

    Science.gov (United States)

    Ibrahim, Amir; Gilerson, Alexander; Chowdhary, Jacek; Ahmed, Samir

    2016-01-01

    Remote sensing has mainly relied on measurements of scalar radiance and its spectral and angular features to retrieve micro- and macro-physical properties of aerosols/hydrosols. However, it is recognized that measurements that include the polarimetric characteristics of light provide more intrinsic information about particulate scattering. To take advantage of this, we used vector radiative transfer (VRT) simulations and developed an analytical relationship to retrieve the macro and micro-physical properties of the oceanic hydrosols. Specifically, we investigated the relationship between the observed degree of linear polarization (DoLP) and the ratio of attenuation-to- absorption coefficients (c/a) in water, from which the scattering coefficient can be readily computed (b equals c minus a), after retrieving a. This relationship was parameterized for various scattering geometries, including sensor zenith/azimuth angles relative to the Sun's principal plane, and for varying Sun zenith angles. An inversion method was also developed for the retrieval of the microphysical properties of hydrosols, such as the bulk refractive index and the particle size distribution. The DoLP vs c/a relationship was tested and validated against in-situ measurements of underwater light polarization obtained by a custom-built polarimeter and measurements of the coefficients a and c, obtained using an in-water WET (Western Environmental Technologies) Labs ac-s (attenuation coefficients In-Situ Spectrophotometer) instrument package. These measurements confirmed the validity of the approach, with retrievals of attenuation coefficients showing a high coefficient of determination depending on the wavelength. We also performed a sensitivity analysis of the DoLP at the Top of Atmosphere (TOA) over coastal waters showing the possibility of polarimetric remote sensing application for ocean color.

  5. Polarimetric ice sounding at P-band: First results

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2009-01-01

    For polar ice sheets valuable stress and strain information can be deduced from the crystal orientation fabric (COF) and its prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties...

  6. Investigation of Polarimetric SAR Data Acquired at Multiple Incidence Angles

    DEFF Research Database (Denmark)

    Svendsen, Morten Thougaard; Skriver, Henning; Thomsen, A.

    1998-01-01

    The dependence of different polarimetric parameters on the incidence angles in the range of 30° to 60° is investigated for a number of different crops using airborne SAR data. The purpose of the investigation is to determine the effect of the variation of incidence angle within a SAR image when...

  7. Polarimetric synthetic aperture radar data and the complex Wishart distribution

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2003-01-01

    When working with multi-look fully polarimetric synthetic aperture radar (SAR) data an appropriate way of representing the backscattered signal consists of the so-called covariance matrix. For each pixel this is a 3 by 3 Hermitian, positive definite matrix which follows a complex Wishart distribu...

  8. Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

  9. Processing of dual-orthogonal cw polarimetric radar signals

    NARCIS (Netherlands)

    Babur, G.

    2009-01-01

    The thesis consists of two parts. The first part is devoted to the theory of dual-orthogonal polarimetric radar signals with continuous waveforms. The thesis presents a comparison of the signal compression techniques, namely correlation and de-ramping methods, for the dual-orthogonal sophisticated

  10. L-Band Polarimetric Correlation Radiometer with Subharmonic Sampling

    DEFF Research Database (Denmark)

    Rotbøll, Jesper; Søbjærg, Sten Schmidl; Skou, Niels

    2001-01-01

    A novel L-band radiometer trading analog complexity for digital ditto has been designed and built. It is a fully polarimetric radiometer of the correlation type and it is based on the sub-harmonic sampling principle in which the L-band signal is directly sampled by a fast A to D converter...

  11. Project PHARUS: Towards a polarimetric C-band airborne SAR

    NARCIS (Netherlands)

    Hoogeboom, P.; Koomen, P.J.; Otten, M.P.G.; Pouwels, H.; Snoeij, P.

    1989-01-01

    A few years ago three institutes in the Netherlands developed a plan to design and build a polarimetric C-band aircraft SAR system of a novel design, called PHARUS (PHased Array Universal SAR), meant as a replacement for our current digital SLAR system. These institutes are the Physics and

  12. Ice sheet anisotropy measured with polarimetric ice sounding radar

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2010-01-01

    For polar ice sheets, valuable stress and strain information can be deduced from crystal orientation fabrics (COF) and their prevailing c-axis alignment. Polarimetric radio echo sounding is a promising technique to measure the anisotropic electromagnetic propagation and reflection properties asso...

  13. A novel L-band polarimetric radiometer featuring subharmonic sampling

    DEFF Research Database (Denmark)

    Rotbøll, J.; Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D...

  14. Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE

    Science.gov (United States)

    Poellot, Michael R.; Kucera, Paul A.

    2004-01-01

    This report describes the work performed by the University of North Dakota (UND) under NASA Grant NAG5-11509, titled Airborne In Situ and Ground-based Polarimetric Radar Measurements of Tropical Convection in Support of CRYSTAL-FACE. This work focused on the collection of data by two key platforms: the UND Citation II research aircraft and the NASA NPOL radar system. The CRYSTAL-FACE (C-F) mission addresses several key issues from the NASA Earth System Enterprise, including the variability of water in the atmosphere, the forcing provided by tropical cirrus and the response of the Earth system to this forcing. In situ measurements and radar observations of tropical convection, cirrus clouds and their environment are core elements of C-F. One of the primary issues that C-F is addressing is the relationship of tropical cirrus anvils to precipitating deep convection. The in situ measurements from C-F are being used to validate remote sensing of Earth-Atmosphere properties, increase our knowledge of upper tropospheric water vapor and its distribution, and increase our knowledge of tropical cirrus cloud morphology and composition. Radar measurements, especially polarimetric diversity observations available fiom the NASA NPOL radar, are providing essential information about the initiation, modulation, and dissipation of convective cores and the generation of associated anvils in tropical convection. Specifically, NPOL radar measurements contain information about convective intensity and its vertical structure for comparison with thermodynamic and kinematic environmental measurements observed from soundings. Because of the polarimetric diversity of MOL, statistics on bulk microphysical properties can be retrieved and compared to the other characteristics of convection and associated cirrus anvils. In summary, the central objectives of this proposal were to deploy the UND Citation research aircraft as an in situ sensing platform for this mission and to provide collaborative

  15. Screening Mississippi River Levees Using Texture-Based and Polarimetric-Based Features from Synthetic Aperture Radar Data

    Directory of Open Access Journals (Sweden)

    Lalitha Dabbiru

    2017-03-01

    Full Text Available This article reviews the use of synthetic aperture radar remote sensing data for earthen levee mapping with an emphasis on finding the slump slides on the levees. Earthen levees built on the natural levees parallel to the river channel are designed to protect large areas of populated and cultivated land in the Unites States from flooding. One of the signs of potential impending levee failure is the appearance of slump slides. On-site inspection of levees is expensive and time-consuming; therefore, a need to develop efficient techniques based on remote sensing technologies is mandatory to prevent failures under flood loading. Analysis of multi-polarized radar data is one of the viable tools for detecting the problem areas on the levees. In this study, we develop methods to detect anomalies on the levee, such as slump slides and give levee managers new tools to prioritize their tasks. This paper presents results of applying the National Aeronautics and Space Administration (NASA Jet Propulsion Lab (JPL’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR quad-polarized L-band data to detect slump slides on earthen levees. The study area encompasses a portion of levees of the lower Mississippi River in the United States. In this paper, we investigate the performance of polarimetric and texture features for efficient levee classification. Texture features derived from the gray level co-occurrence (GLCM matrix and discrete wavelet transform were computed and analyzed for efficient levee classification. The pixel-based polarimetric decomposition features, such as entropy, anisotropy, and scattering angle were also computed and applied to the support vector machine classifier to characterize the radar imagery and compared the results with texture-based classification. Our experimental results showed that inclusion of textural features derived from the SAR data using the discrete wavelet transform (DWT features and GLCM features provided

  16. Analysis of Radarsat-2 Full Polarimetric Data for Forest Mapping

    Science.gov (United States)

    Maghsoudi, Yasser

    Forests are a major natural resource of the Earth and control a wide range of environmental processes. Forests comprise a major part of the planet's plant biodiversity and have an important role in the global hydrological and biochemical cycles. Among the numerous potential applications of remote sensing in forestry, forest mapping plays a vital role for characterization of the forest in terms of species. Particularly, in Canada where forests occupy 45% of the territory, representing more than 400 million hectares of the total Canadian continental area. In this thesis, the potential of polarimetric SAR (PolSAR) Radarsat-2 data for forest mapping is investigated. This thesis has two principle objectives. First is to propose algorithms for analyzing the PolSAR image data for forest mapping. There are a wide range of SAR parameters that can be derived from PolSAR data. In order to make full use of the discriminative power offered by all these parameters, two categories of methods are proposed. The methods are based on the concept of feature selection and classifier ensemble. First, a nonparametric definition of the evaluation function is proposed and hence the methods NFS and CBFS. Second, a fast wrapper algorithm is proposed for the evaluation function in feature selection and hence the methods FWFS and FWCBFS. Finally, to incorporate the neighboring pixels information in classification an extension of the FWCBFS method i.e. CCBFS is proposed. The second objective of this thesis is to provide a comparison between leaf-on (summer) and leaf-off (fall) season images for forest mapping. Two Radarsat-2 images acquired in fine quad-polarized mode were chosen for this study. The images were collected in leaf-on and leaf-off seasons. We also test the hypothesis whether combining the SAR parameters obtained from both images can provide better results than either individual datasets. The rationale for this combination is that every dataset has some parameters which may be

  17. VLBA polarimetric monitoring of 3C 111

    Science.gov (United States)

    Beuchert, T.; Kadler, M.; Perucho, M.; Großberger, C.; Schulz, R.; Agudo, I.; Casadio, C.; Gómez, J. L.; Gurwell, M.; Homan, D.; Kovalev, Y. Y.; Lister, M. L.; Markoff, S.; Molina, S. N.; Pushkarev, A. B.; Ros, E.; Savolainen, T.; Steinbring, T.; Thum, C.; Wilms, J.

    2018-02-01

    Context. While studies of large samples of jets of active galactic nuclei (AGN) are important in order to establish a global picture, dedicated single-source studies are an invaluable tool for probing crucial processes within jets on parsec scales. These processes involve in particular the formation and geometry of the jet magnetic field as well as the flow itself. Aims: We aim to better understand the dynamics within relativistic magneto-hydrodynamical flows in the extreme environment and close vicinity of supermassive black holes. Methods: We analyze the peculiar radio galaxy 3C 111, for which long-term polarimetric observations are available. We make use of the high spatial resolution of the VLBA network and the MOJAVE monitoring program, which provides high data quality also for single sources and allows us to study jet dynamics on parsec scales in full polarization with an evenly sampled time-domain. While electric vectors can probe the underlying magnetic field, other properties of the jet such as the variable (polarized) flux density, feature size, and brightness temperature, can give valuable insights into the flow itself. We complement the VLBA data with data from the IRAM 30-m Telescope as well as the SMA. Results: We observe a complex evolution of the polarized jet. The electric vector position angles (EVPAs) of features traveling down the jet perform a large rotation of ≳180∘ across a distance of about 20 pc. As opposed to this smooth swing, the EVPAs are strongly variable within the first parsecs of the jet. We find an overall tendency towards transverse EVPAs across the jet with a local anomaly of aligned vectors in between. The polarized flux density increases rapidly at that distance and eventually saturates towards the outermost observable regions. The transverse extent of the flow suddenly decreases simultaneously to a jump in brightness temperature around where we observe the EVPAs to turn into alignment with the jet flow. Also the gradient

  18. 3D-copper oxide and copper oxide/few-layer graphene with screen printed nanosheet assembly for ultrasensitive non-enzymatic glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhimei [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Pan, Peng, E-mail: panpeny@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Liu, Xuewen [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Yang, Zhengchun; Wei, Jun [Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Wei, Zhen, E-mail: weizhenxinxi@163.com [Tianjin Key Laboratory of Film Electronic and Communicate Devices, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China); Advanced Materials and Printed Electronics Center, School of Electronics Information Engineering, Tianjin University of Technology, Tianjin, 300384 (China)

    2017-02-01

    Screen-printed copper oxide (CuO) and CuO/few-layer graphene on graphite electrodes were used to fabricate the ultrasensitive nonenzymatic glucose biosensors. Flower-like CuO and flower-like CuO/few-layer graphene composites were prepared by screen-printing method and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HETEM). On the basis of their cyclic voltammetry (CV) and chronoamperometry results, it was concluded that the addition of graphene to CuO significantly improved the performance of the fabricated glucose sensors, exhibiting high and reproducible sensitivity of 3120 μAmM{sup −1} cm{sup −2} with three linear ranges from 4 μM to 13.5 mM and the detection limit of 4 μM (S/N = 3) in a fast response time of 2 s. In addition, the fabricated sensors could effectively avoid the disturbance by interferents, such as Ascorbic Acid (AA), Uric Acid (UA), and Dopamine (DA). Most importantly, the testing results of real blood serum samples demonstrated that the electrodes were applicable and acceptable for the determination of glucose concentrations in human serum. The efficiencies of two non-enzymatic glucose biosensors for glucose determination were comparable with that of a commercial enzymatic sensor. - Highlights: • The method 2D nanosheet turns to 3D microflower by using screen printing was proposed. • Few-layer graphene added improved the sensor’s performance on base of CuO functional material. • Two ultrasensitive non-enzymatic glucose sensors were successfully fabricated. • The proposed sensor shows a high sensitivity of 3120 μA mM{sup −1} cm{sup −2}.

  19. Two glucose transporters in Saccharomyces cerevisiae are glucose sensors that generate a signal for induction of gene expression.

    OpenAIRE

    Ozcan, S; Dover, J; Rosenwald, A G; Wölfl, S; Johnston, M

    1996-01-01

    Glucose is the preferred carbon source for most eukaryotic cells and has profound effects on many cellular functions. How cells sense glucose and transduce a signal into the cell is a fundamental, unanswered question. Here we describe evidence that two unusual glucose transporters in the yeast Saccharomyces cerevisiae serve as glucose sensors that generate an intracellular glucose signal. The Snf3p high-affinity glucose transporter appears to function as a low glucose sensor, since it is requ...

  20. Image Enhancement and Speckle Reduction of Full Polarimetric SAR Data by Gaussian Markov Random Field

    Science.gov (United States)

    Mahdian, M.; Motagh, M.; Akbari, V.

    2013-09-01

    In recent years, the use of Polarimetric Synthetic Aperture Radar (PolSAR) data in different applications dramatically has been increased. In SAR imagery an interference phenomenon with random behavior exists which is called speckle noise. The interpretation of data encounters some troubles due to the presence of speckle which can be considered as a multiplicative noise affecting all coherent imaging systems. Indeed, speckle degrade radiometric resolution of PolSAR images, therefore it is needful to perform speckle filtering on the SAR data type. Markov Random Field (MRF) has proven to be a powerful method for drawing out eliciting contextual information from remotely sensed images. In the present paper, a probability density function (PDF), which is fitted well with the PolSAR data based on the goodness-of-fit test, is first obtained for the pixel-wise analysis. Then the contextual smoothing is achieved with the MRF method. This novel speckle reduction method combines an advanced statistical distribution with spatial contextual information for PolSAR data. These two parts of information are combined based on weighted summation of pixel-wise and contextual models. This approach not only preserves edge information in the images, but also improves signal-to-noise ratio of the results. The method maintains the mean value of original signal in the homogenous areas and preserves the edges of features in the heterogeneous regions. Experiments on real medium resolution ALOS data from Tehran, and also high resolution full polarimetric SAR data over the Oberpfaffenhofen test-site in Germany, demonstrate the effectiveness of the algorithm compared with well-known despeckling methods.

  1. AirMOSS: L1 S-0 Polarimetric Data from AirMOSS P-band SAR, La Selva, 2012-2015

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides level 1 (L1) polarimetric radar backscattering coefficient (sigma-0), multilook complex, polarimetrically calibrated, and georeferenced data...

  2. Recent progress in multidimensional optical sensing and imaging systems (MOSIS)

    Science.gov (United States)

    Shen, Xin; Javidi, Bahram

    2017-05-01

    We present recent progress of the previously reported Multidimensional Optical Sensing and Imaging Systems (MOSIS) 2.0 for target recognition, material inspection and integrated visualization. The degrees of freedom of MOSIS 2.0 include three-dimensional (3D) imaging, polarimetric imaging and multispectral imaging. Each of these features provides unique information about a scene. 3D computationally reconstructed images mitigate the occlusion in front of the object, which can be used for 3D object recognition. The degree of polarization (DoP) of the light reflected from object surface is measured by 3D polarimetric imaging. Multispectral imaging is able to segment targets with specific spectral properties.

  3. SAR Polarimetric Scattering from Natural Terrains

    Science.gov (United States)

    2017-02-17

    ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) AOARD UNIT 45002 APO AP 96338-5002 10. SPONSOR/MONITOR’S ACRONYM(S...unlimited. (3) Multiple Scattering Effects with Cyclical Terms in Active Remote Sensing of Vegetated Surface Using Vector Radiative Transfer Theory ...Vector Radiative Transfer Theory Date : 2016/4/4 Authors : T.-H. Liao, S.-B. Kim, S. Tan, L. Tsang, C. Su, T. J. Jackson [6] Journal name : IEEE

  4. Spectral and Polarimetric Imagery Collection Experiment

    Science.gov (United States)

    2011-12-01

    imager if each mini-lens is followed by a band-pass filter. For this system, a set of four linear wire- grid polarizers are used, oriented at angles 0...is that of a 2S3 howitzer that was developed and produced for an ARDEC smart munitions program (Sense and Destroy Armor – SADARM). The PAL...using Imagej, Metlab, or any other program that can read test images for further processing and image analysis. The PAL metrological database can

  5. INVENTORY OF IRRIGATED RICE ECOSYSTEM USING POLARIMETRIC SAR DATA

    Directory of Open Access Journals (Sweden)

    P. Srikanth

    2012-08-01

    Full Text Available An attempt has been made in the current study to assess the potential of polarimetric SAR data for inventory of kharif rice and the major competing crop like cotton. In the process, physical process of the scattering mechanisms occurring in rice and cotton crops at different phonological stages was studied through the use of temporal Radarsat 2 Fine quadpol SAR data. The temporal dynamics of the volume, double and odd bounce, entropy, anisotropy, alpha parameters and polarimertic signatures, classification through isodata clustering and Wishart techniques were assessed. The Wishart (H-a classification showed higher overall as well as rice and cotton crop accuracies compared to the isodata clustering from Freeman 3-component decomposition. The classification of temporal SAR data sets independently showed that the rice crop forecasting can be advanced with the use of appropriate single date polarimetric SAR data rather than using temporal SAR amplitude data sets with the single polarization in irrigated rice ecosystems

  6. Multispectral and polarimetric photodetection using a plasmonic metasurface

    Science.gov (United States)

    Pelzman, Charles; Cho, Sang-Yeon

    2018-01-01

    We present a metasurface-integrated Si 2-D CMOS sensor array for multispectral and polarimetric photodetection applications. The demonstrated sensor is based on the polarization selective extraordinary optical transmission from periodic subwavelength nanostructures, acting as artificial atoms, known as meta-atoms. The meta-atoms were created by patterning periodic rectangular apertures that support optical resonance at the designed spectral bands. By spatially separating meta-atom clusters with different lattice constants and orientations, the demonstrated metasurface can convert the polarization and spectral information of an optical input into a 2-D intensity pattern. As a proof-of-concept experiment, we measured the linear components of the Stokes parameters directly from captured images using a CMOS camera at four spectral bands. Compared to existing multispectral polarimetric sensors, the demonstrated metasurface-integrated CMOS system is compact and does not require any moving components, offering great potential for advanced photodetection applications.

  7. Three Dimensional Polarimetric Neutron Tomography of Magnetic Fields

    DEFF Research Database (Denmark)

    Sales, Morten; Strobl, Markus; Shinohara, Takenao

    2018-01-01

    -destructively with the potential to probe the interior of bulk samples which is not amenable otherwise. Using a pioneering polarimetric set-up for ToF neutron instrumentation in combination with a newly developed tailored reconstruction algorithm, the magnetic field generated by a current carrying solenoid has been measured......Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non...... and reconstructed, thereby providing the proof-of-principle of a technique able to reveal hitherto unobtainable information on the magnetic fields in the bulk of materials and devices, due to a high degree of penetration into many materials, including metals, and the sensitivity of neutron polarisation to magnetic...

  8. Glycolysis Controls Plasma Membrane Glucose Sensors To Promote Glucose Signaling in Yeasts

    Science.gov (United States)

    Cairey-Remonnay, Amélie; Deffaud, Julien; Wésolowski-Louvel, Micheline; Lemaire, Marc

    2014-01-01

    Sensing of extracellular glucose is necessary for cells to adapt to glucose variation in their environment. In the respiratory yeast Kluyveromyces lactis, extracellular glucose controls the expression of major glucose permease gene RAG1 through a cascade similar to the Saccharomyces cerevisiae Snf3/Rgt2/Rgt1 glucose signaling pathway. This regulation depends also on intracellular glucose metabolism since we previously showed that glucose induction of the RAG1 gene is abolished in glycolytic mutants. Here we show that glycolysis regulates RAG1 expression through the K. lactis Rgt1 (KlRgt1) glucose signaling pathway by targeting the localization and probably the stability of Rag4, the single Snf3/Rgt2-type glucose sensor of K. lactis. Additionally, the control exerted by glycolysis on glucose signaling seems to be conserved in S. cerevisiae. This retrocontrol might prevent yeasts from unnecessary glucose transport and intracellular glucose accumulation. PMID:25512610

  9. Retrieval of ice thickness from polarimetric SAR data

    Science.gov (United States)

    Kwok, R.; Yueh, S. H.; Nghiem, S. V.; Huynh, D. D.

    1993-01-01

    We describe a potential procedure for retrieving ice thickness from multi-frequency polarimetric SAR data for thin ice. This procedure includes first masking out the thicker ice types with a simple classifier and then deriving the thickness of the remaining pixels using a model-inversion technique. The technique used to derive ice thickness from polarimetric observations is provided by a numerical estimator or neural network. A three-layer perceptron implemented with the backpropagation algorithm is used in this investigation with several improved aspects for a faster convergence rate and a better accuracy of the neural network. These improvements include weight initialization, normalization of the output range, the selection of offset constant, and a heuristic learning algorithm. The performance of the neural network is demonstrated by using training data generated by a theoretical scattering model for sea ice matched to the database of interest. The training data are comprised of the polarimetric backscattering coefficients of thin ice and the corresponding input ice parameters to the scattering model. The retrieved ice thickness from the theoretical backscattering coefficients is compare with the input ice thickness to the scattering model to illustrate the accuracy of the inversion method. Results indicate that the network convergence rate and accuracy are higher when multi-frequency training sets are presented. In addition, the dominant backscattering coefficients in retrieving ice thickness are found by comparing the behavior of the network trained backscattering data at various incidence angels. After the neural network is trained with the theoretical backscattering data at various incidence anges, the interconnection weights between nodes are saved and applied to the experimental data to be investigated. In this paper, we illustrate the effectiveness of this technique using polarimetric SAR data collected by the JPL DC-8 radar over a sea ice scene.

  10. Change detection in a time series of polarimetric SAR data

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Skriver, Henning

    2014-01-01

    A test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution with an associated probability of finding a smaller value of the test statistic is introduced. Unlike tests based on pairwise comparisons between all temporally consecutive acquisi...... acquisitions the new omnibus test statistic and the probability measure successfully detects change in two short series of L- and C-band polarimetric EMISAR data....

  11. Polarimetric signatures of sea ice. 1: Theoretical model

    Science.gov (United States)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structral, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarmetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies to interpretation of sea ice polarimetric signatures.

  12. Hydrometeor classification from polarimetric radar measurements: a clustering approach

    Directory of Open Access Journals (Sweden)

    J. Grazioli

    2015-01-01

    Full Text Available A data-driven approach to the classification of hydrometeors from measurements collected with polarimetric weather radars is proposed. In a first step, the optimal number of hydrometeor classes (nopt that can be reliably identified from a large set of polarimetric data is determined. This is done by means of an unsupervised clustering technique guided by criteria related both to data similarity and to spatial smoothness of the classified images. In a second step, the nopt clusters are assigned to the appropriate hydrometeor class by means of human interpretation and comparisons with the output of other classification techniques. The main innovation in the proposed method is the unsupervised part: the hydrometeor classes are not defined a priori, but they are learned from data. The approach is applied to data collected by an X-band polarimetric weather radar during two field campaigns (from which about 50 precipitation events are used in the present study. Seven hydrometeor classes (nopt = 7 have been found in the data set, and they have been identified as light rain (LR, rain (RN, heavy rain (HR, melting snow (MS, ice crystals/small aggregates (CR, aggregates (AG, and rimed-ice particles (RI.

  13. Searching for Jet Emission in LMXBs: A Polarimetric View

    Directory of Open Access Journals (Sweden)

    Maria Cristina Baglio

    2017-10-01

    Full Text Available We present results taken from a study aiming at detecting the emission from relativistic particles jets in neutron star-low mass X-ray binaries using optical polarimetric observations. First, we focus on a polarimetric study performed on the persistent LMXB 4U 0614+091. Once corrected for interstellar effects, we measured an intrinsic linear polarization in the r-band of ~3% at a 3σ confidence level. This is in-line with the observation of an infrared excess in the spectral energy distribution (SED of the source, reported in a previous work, which the authors linked to the optically thin synchrotron emission of a jet. We then present a study performed on the transitional millisecond pulsar PSR J1023+0038 during quiescence. We measured a linear polarization of 1.09 ± 0.27% and 0.90 ± 0.17% in the V and R bands, respectively. The phase-resolved polarimetric curve of the source in the R-band reveals a hint of a sinusoidal modulation at the source orbital period. The NIR -optical SED of the system did not suggest the presence of a jet. We conclude that the optical linear polarization observed for PSR J1023+0038 is possibly due to Thomson scattering with electrons in the disc, as also suggested by the hint of the modulation of the R-band linear polarization at the system orbital period.

  14. Interpulse phase coding for improving accuracy of polarimetric SAR

    Science.gov (United States)

    Giuli, Dino; Facheris, Luca

    1993-02-01

    Polarimetric measurements made by Synthetic Aperture Radar (SAR) may be in some cases, depending on the polarimetric response of distributed targets to be imaged, severely limited in their accuracy due to the joint effect of range ambiguities and weak crosspolarized signal response. Due to the utilization of alternate transmission of pulses at orthogonal polarizations, each ambiguous swath gives rise to one different kind of interference, depending whether its order is even or odd. Interference arising from even-order ambiguous swaths, differently from that arising from odd-order swaths, is generated by pulses transmitted on the same polarization channel of the pulse soliciting the desired echo signal, that they corrupt. Evidently, interference arising from odd-order swaths and affecting crosspolar measurements is most harmful, together with that arising from zones at low incidence angle, which carries a strong reflectivity contribution to the total interference on the desired signal. The paper discusses the utility of appropriate interpulse phase coding strategies, depending on the SAR geometry, than can be devised and utilized in the polarimetric interleaved-pulse measurement technique, with the task to reduce the interference generated by range ambiguities and affecting those target scattering matrix elements, whose measurement is expected to be most critical.

  15. Geologic mapping in Greenland with polarimetric SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Madsen, Søren Nørvang; Brooks, C. K.

    1995-01-01

    mapping is complicated by an extreme topography leading to massive shadowing, foreshortening and layover. An artifact characterised by high cross-polarisation is observed behind many sharp mountain ridges. A multi-reflection hypothesis has been investigated without finding the ultimate proof......The application of synthetic aperture radar (SAR) for geologic mapping in Greenland is investigated by the Danish Center for Remote Sensing (DCRS) in co-operation with the Danish Lithosphere Centre (DLC). In 1994 a pilot project was conducted in East Greenland. The Danish airborne SAR, EMISAR...

  16. A novel hierarchical 3D N-Co-CNT@NG nanocomposite electrode for non-enzymatic glucose and hydrogen peroxide sensing applications.

    Science.gov (United States)

    Balamurugan, Jayaraman; Thanh, Tran Duy; Karthikeyan, Gopalsamy; Kim, Nam Hoon; Lee, Joong Hee

    2017-03-15

    A novel 3D nanocomposite of nitrogen doped Co-CNTs over graphene sheets (3D N-Co-CNT@NG) have been successfully fabricated via a simple, scalable and one-step thermal decomposition method. This 3D hierarchical nanostructure provides an admirable conductive network for effective charge transfer and avoids the agglomeration of NG matrices, which examine direct as well as non-enzymatic responses to glucose oxidation and H 2 O 2 reduction at a low potential. The novel electrode showed excellent electrochemical performance towards glucose oxidation, with high sensitivity of 9.05μAcm -2 mM -1 , a wide linear range from 0.025 to 10.83mM, and a detection limit of 100nM with a fast response time of less than 3s. Furthermore, non-enzymatic H 2 O 2 sensors based on the 3D N-Co-CNT@NG electrode exhibited high sensitivity (28.66μAmM -1 cm -2 ), wide linear range (2.0-7449μM), low detection limit of 2.0μM (S/N=3), excellent selectivity, decent reproducibility and long term stability. Such outstanding electrochemical performance can be endorsed to the large electroactive surface area, unique porous architecture, highly conductive networks, and synergistic interaction between N-Co-CNTs and nitrogen doped graphene (NG) in the novel 3D nanocomposite. This facile, cost-effective, sensitive, and selective glucose as well as H 2 O 2 sensors are also proven to be appropriate for the detection of glucose as well as H 2 O 2 in human serum. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

    Energy Technology Data Exchange (ETDEWEB)

    Sakalak, Huseyin [Selcuk University, Metallurgy and Materials Engineering (Turkey); Ulasan, Mehmet; Yavuz, Emine [Selcuk University, Advanced Technology Research and Application Center (Turkey); Camli, Sevket Tolga, E-mail: tolgacamli@gmail.com [Biyotez Machinery Chemistry R& D Co. Ltd. (Turkey); Yavuz, Mustafa Selman, E-mail: selmanyavuz@selcuk.edu.tr [Selcuk University, Metallurgy and Materials Engineering (Turkey)

    2014-12-15

    Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV–Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells.

  18. A theoretical and numerical study of polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum

    Science.gov (United States)

    Yueh, S. H.; Kwok, R.

    1993-01-01

    In this paper, theoretical and numerical results of the polarimetric scattering and emission from random rough surfaces with anisotropic directional spectrum are presented for the remote sensing of ocean and soil surfaces. The polarimetric scattered field for rough dielectric surfaces is derived to the second order by the small perturbation method (SPM). It is found that the second-order scattered field is coherent in nature, and its coefficients for different polarizations present the lowest-order corrections to the Fresnel reflection coefficients of the surfaces. In addition, the cross-polarized (HV and VH) components of the coherent fields are reciprocal and not zero for surfaces with anisotropic directional spectrum when the azimuth angle of the incident direction is not aligned with the symmetry directions of surfaces. In order to verify the energy conservation condition of the theoretical results, which is important if the theory is to be applied to the passive polarimetry of rough surfaces, a Monte Carlo simulation is performed to numerically calculate the polarimetric reflectivities of one-dimensional random rough surfaces which are generated with a prescribed power-law spectrum in the spectral domain and transformed to the spatial domain by the FFT. The surfaces simulated by this approach are periodic with the period corresponding to the low-wavenumber cutoff. To calculate the scattering from periodic dielectric surfaces, the authors present a new numerical technique which applies the Floquet theorem to reduce the problem to one period and does not require the evaluation of one-dimensional periodic Green's function used in the conventional method of moment formulation. Once the scattering coefficients are obtained, the polarimetric Stokes vectors for the emission from the random surfaces are then calculated according to the Kirchhoff's law and are illustrated as functions of relative azimuth observation and row directions. The second-order SPM is also

  19. Glucose repression in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kayikci, Omur; Nielsen, Jens

    2015-01-01

    Glucose is the primary source of energy for the budding yeast Saccharomyces cerevisiae. Although yeast cells can utilize a wide range of carbon sources, presence of glucose suppresses molecular activities involved in the use of alternate carbon sources as well as it represses respiration...... and gluconeogenesis. This dominant effect of glucose on yeast carbon metabolism is coordinated by several signaling and metabolic interactions that mainly regulate transcriptional activity but are also effective at post-transcriptional and post-translational levels. This review describes effects of glucose repression...... on yeast carbon metabolism with a focus on roles of the Snf3/Rgt2 glucose-sensing pathway and Snf1 signal transduction in establishment and relief of glucose repression....

  20. Integrating polarimetric synthetic aperture radar and imaging spectrometry for wildland fuel mapping in southern California

    Science.gov (United States)

    P.E. Dennison; D.A. Roberts; J. Regelbrugge; S.L. Ustin

    2000-01-01

    Polarimetric synthetic aperture radar (SAR) and imaging spectrometry exemplify advanced technologies for mapping wildland fuels in chaparral ecosystems. In this study, we explore the potential of integrating polarimetric SAR and imaging spectrometry for mapping wildland fuels. P-band SAR and ratios containing P-band polarizations are sensitive to variations in stand...

  1. Spectral Polarimetric Features Analysis of Wind Turbine Clutter in Weather Radar

    NARCIS (Netherlands)

    Yin, J.; Krasnov, O.A.; Unal, C.M.H.; Medagli, S.; Russchenberg, H.W.J.

    2017-01-01

    Wind turbine clutter has gradually become a concern for the radar community for its increasing size and quantity worldwide. Based on the S-band polarimetric Doppler PARSAX radar measurements, this paper demonstrates the micro-Doppler features and spectral-polarimetric characteristic of wind turbine

  2. Polsar Land Cover Classification Based on Hidden Polarimetric Features in Rotation Domain and Svm Classifier

    Science.gov (United States)

    Tao, C.-S.; Chen, S.-W.; Li, Y.-Z.; Xiao, S.-P.

    2017-09-01

    Land cover classification is an important application for polarimetric synthetic aperture radar (PolSAR) data utilization. Rollinvariant polarimetric features such as H / Ani / text-decoration: overline">α / Span are commonly adopted in PolSAR land cover classification. However, target orientation diversity effect makes PolSAR images understanding and interpretation difficult. Only using the roll-invariant polarimetric features may introduce ambiguity in the interpretation of targets' scattering mechanisms and limit the followed classification accuracy. To address this problem, this work firstly focuses on hidden polarimetric feature mining in the rotation domain along the radar line of sight using the recently reported uniform polarimetric matrix rotation theory and the visualization and characterization tool of polarimetric coherence pattern. The former rotates the acquired polarimetric matrix along the radar line of sight and fully describes the rotation characteristics of each entry of the matrix. Sets of new polarimetric features are derived to describe the hidden scattering information of the target in the rotation domain. The latter extends the traditional polarimetric coherence at a given rotation angle to the rotation domain for complete interpretation. A visualization and characterization tool is established to derive new polarimetric features for hidden information exploration. Then, a classification scheme is developed combing both the selected new hidden polarimetric features in rotation domain and the commonly used roll-invariant polarimetric features with a support vector machine (SVM) classifier. Comparison experiments based on AIRSAR and multi-temporal UAVSAR data demonstrate that compared with the conventional classification scheme which only uses the roll-invariant polarimetric features, the proposed classification scheme achieves both higher classification accuracy and better robustness. For AIRSAR data, the overall classification

  3. Printing graphene-carbon nanotube-ionic liquid gel on graphene paper: Towards flexible electrodes with efficient loading of PtAu alloy nanoparticles for electrochemical sensing of blood glucose.

    Science.gov (United States)

    He, Wenshan; Sun, Yimin; Xi, Jiangbo; Abdurhman, Abduraouf Alamer Mohamed; Ren, Jinghua; Duan, Hongwei

    2016-01-15

    The increasing demands for portable, wearable, and implantable sensing devices have stimulated growing interest in innovative electrode materials. In this work, we have demonstrated that printing a conductive ink formulated by blending three-dimensional (3D) porous graphene-carbon nanotube (CNT) assembly with ionic liquid (IL) on two-dimensional (2D) graphene paper (GP), leads to a freestanding GP supported graphene-CNT-IL nanocomposite (graphene-CNT-IL/GP). The incorporation of highly conductive CNTs into graphene assembly effectively increases its surface area and improves its electrical and mechanical properties. The graphene-CNT-IL/GP, as freestanding and flexible substrates, allows for efficient loading of PtAu alloy nanoparticles by means of ultrasonic-electrochemical deposition. Owing to the synergistic effect of PtAu alloy nanoparticles, 3D porous graphene-CNT scaffold, IL binder and 2D flexible GP substrate, the resultant lightweight nanohybrid paper electrode exhibits excellent sensing performances in nonenzymatic electrochemical detection of glucose in terms of sensitivity, selectivity, reproducibility and mechanical properties. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Polarimetric radar characteristics of storms with and without lightning activity

    Science.gov (United States)

    Mattos, Enrique V.; Machado, Luiz A. T.; Williams, Earle R.; Albrecht, Rachel I.

    2016-12-01

    This paper analyzes the cloud microphysics in different layers of storms as a function of three-dimensional total lightning density. A mobile X-band polarimetric radar and very high frequency (VHF) sources from Lightning Mapping Array (LMA) observations during the 2011/2012 Brazil spring-summer were used to determine the microphysical signatures of radar vertical profiles and lightning density. This study quantified the behavior of 5.3 million vertical profiles of the horizontal reflectivity (ZH), differential reflectivity (ZDR), specific differential phase (KDP), and correlation coefficient (ρHV). The principal changes in the polarimetric variables occurred only for VHF source rate density greater than 14 VHF sources per km2 in 4 min. These storms showed an enhanced positive KDP in the mixed 1 layer (from 0 to -15°C) probably associated with supercooled liquid water signatures, whereas regions with negative ZDR and KDP and moderate ZH in the mixed 2 layer (from -15 to -40°C) were possibly associated with the presence of conical graupel. The glaciated (above -40°C) and upper part of the mixed 2 layers showed a significant trend to negative KDP with an increase in lightning density, in agreement with vertical alignment of ice particle by the cloud electric field. A conceptual model that presents the microphysical signatures in storms with and without lightning activity was constructed. The observations documented in this study provide an understanding of how the combinations of polarimetric variables could help to identify storms with different lightning density and vice versa.

  5. Polarimetric purity and the concept of degree of polarization

    Science.gov (United States)

    Gil, José J.; Norrman, Andreas; Friberg, Ari T.; Setälä, Tero

    2018-02-01

    The concept of degree of polarization for electromagnetic waves, in its general three-dimensional version, is revisited in the light of the implications of the recent findings on the structure of polarimetric purity and of the existence of nonregular states of polarization [J. J. Gil et al., Phys Rev. A 95, 053856 (2017), 10.1103/PhysRevA.95.053856]. From the analysis of the characteristic decomposition of a polarization matrix R into an incoherent convex combination of (1) a pure state Rp, (2) a middle state Rm given by an equiprobable mixture of two eigenstates of R, and (3) a fully unpolarized state Ru -3 D, it is found that, in general, Rm exhibits nonzero circular and linear degrees of polarization. Therefore, the degrees of linear and circular polarization of R cannot always be assigned to the single totally polarized component Rp. It is shown that the parameter P3 D proposed formerly by Samson [J. C. Samson, Geophys. J. R. Astron. Soc. 34, 403 (1973), 10.1111/j.1365-246X.1973.tb02404.x] takes into account, in a proper and objective form, all the contributions to polarimetric purity, namely, the contributions to the linear and circular degrees of polarization of R as well as to the stability of the plane containing its polarization ellipse. Consequently, P3 D constitutes a natural representative of the degree of polarimetric purity. Some implications for the common convention for the concept of two-dimensional degree of polarization are also analyzed and discussed.

  6. Astrocytic Insulin Signaling Couples Brain Glucose Uptake with Nutrient Availability

    NARCIS (Netherlands)

    García-Cáceres, Cristina; Quarta, Carmelo; Varela, Luis; Gao, Yuanqing; Gruber, Tim; Legutko, Beata; Jastroch, Martin; Johansson, Pia; Ninkovic, Jovica; Yi, Chun-Xia; Le Thuc, Ophelia; Szigeti-Buck, Klara; Cai, Weikang; Meyer, Carola W.; Pfluger, Paul T.; Fernandez, Ana M.; Luquet, Serge; Woods, Stephen C.; Torres-Alemán, Ignacio; Kahn, C. Ronald; Götz, Magdalena; Horvath, Tamas L.; Tschöp, Matthias H.

    2016-01-01

    We report that astrocytic insulin signaling co-regulates hypothalamic glucose sensing and systemic glucose metabolism. Postnatal ablation of insulin receptors (IRs) in glial fibrillary acidic protein (GFAP)-expressing cells affects hypothalamic astrocyte morphology, mitochondrial function, and

  7. Facile One-Step Microwave-Assisted Route towards Ni Nanospheres/Reduced Graphene Oxide Hybrids for Non-Enzymatic Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Mojiao Zhou

    2012-04-01

    Full Text Available In this work, a facile one-step microwave-assisted method for deposition of monodisperse Ni nanospheres on reduced graphene oxide (rGO sheets to form Ni-rGO nanohybrids is discussed. In the presence of hydrazine monohydrate, Ni nanospheres are grown onto rGO sheets using nickel precursor and GO as starting materials in ethylene glycol (EG solution under a low level of microwave irradiation (300 W for 20 min, during which GO is also reduced to rGO. The as-prepared nanohybrids exhibit well-dispersed Ni nanosphere (about 80 nm in diameter loadings and effective reduction of graphene oxide. The resulting Ni-rGO nanohybrids-modified glassy carbon electrode (GCE shows significantly improved electrochemical performance in nonenzymatic amperometric glucose detection. In addition, interference from the oxidation of common interfering species under physiological conditions, such as ascorbic acid (AA and uric acid (UA, is effectively avoided.

  8. Beaconless search and rescue using polarimetric synthetic aperture radar

    Science.gov (United States)

    McCandless, Samuel W.; Huxtable, Barton D.; Mansfield, Arthur W.; Wallace, Ronald; Larsen, Rudolph; Rais, Houra

    1996-03-01

    In developing a beaconless search and rescue capability to quickly locate small aircraft that have crashed in remote areas, NASA's Search and Rescue (S&R) Program brings together advanced polarimetric synthetic aperture radar processing, field and laboratory tests, and state-of-the-art automated target detection algorithms. This paper provides the status of this program, which began with experiments conducted in concert with the JPL DC-8 AirSAR in 1989 at the Duke University Forest. The program is being conducted by NASA's Goddard Space Flight Center (GSFC) under the auspices of the Search and Rescue Office.

  9. HAWC+/SOFIA Polarimetric Observations of OMC-1

    Science.gov (United States)

    Chuss, David; Andersson, B.-G.; Bally, John; Dowell, Charles D.; Harper, Doyal; Lazarian, Alex; Michail, Joseph M.; Morris, Mark; Novak, Giles; Siah, Javad; Vaillancourt, John; Werner, Michael; HAWC+ Science Team

    2018-01-01

    Astrophysical dust grains become partially aligned due to magnetic fields that permeate the interstellar medium. Measurements of far-infrared polarized emission provide a tool to characterize magnetic fields and test their effect on star formation in molecular clouds. The HAWC+ camera provides polarimetric imaging capability for SOFIA in four bands between 50 and 300 microns. As part of the science commissioning of the instrument, HAWC+ has obtained more than 1000 independent measurements of polarization in the OMC-1 star forming region. The observations were made at a wavelength of 89 microns with an angular resolution of 8 arcseconds. We present these preliminary data and initial analysis.

  10. Three axis vector atomic magnetometer utilizing polarimetric technique

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Swarupananda, E-mail: spradhan@barc.gov.in, E-mail: pradhans75@gmail.com [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India and Homi Bhabha National Institute, Department of Atomic Energy, Mumbai 400094 (India)

    2016-09-15

    The three axis vector magnetic field measurement based on the interaction of a single elliptically polarized light beam with an atomic system is described. The magnetic field direction dependent atomic responses are extracted by the polarimetric detection in combination with laser frequency modulation and magnetic field modulation techniques. The magnetometer geometry offers additional critical requirements like compact size and large dynamic range for space application. Further, the three axis magnetic field is measured using only the reflected signal (one polarization component) from the polarimeter and thus can be easily expanded to make spatial array of detectors and/or high sensitivity field gradient measurement as required for biomedical application.

  11. Glucose gradient differences in subcutaneous tissue of healthy volunteers assessed with ultraslow microdialysis and a nanolitre glucose sensor

    NARCIS (Netherlands)

    Tiessen, RG; Rhemrev-Boom, MM; Korf, J

    2002-01-01

    The abdominal subcutaneous interstitium is easily accessible for monitoring glucose for Diabetes Mellitus research and management. The available glucose sensing devices demand frequent blood sampling by finger pricking for calibration. Moreover, there is controversy about the exact relationship

  12. Glucose allostasis

    DEFF Research Database (Denmark)

    Stumvoll, Michael; Tataranni, P Antonio; Stefan, Norbert

    2003-01-01

    In many organisms, normoglycemia is achieved by a tight coupling of nutrient-stimulated insulin secretion in the pancreatic beta-cell (acute insulin response [AIR]) and the metabolic action of insulin to stimulate glucose disposal (insulin action [M]). It is widely accepted that in healthy...... individuals with normal glucose tolerance, normoglycemia can always be maintained by compensatorily increasing AIR in response to decreasing M (and vice versa). This has been mathematically described by the hyperbolic relationship between AIR and M and referred to as glucose homeostasis, with glucose...... concentration assumed to remain constant along the hyperbola. Conceivably, glucose is one of the signals stimulating AIR in response to decreasing M. Hypothetically, as with any normally functioning feed-forward system, AIR should not fully compensate for worsening M, since this would remove the stimulus...

  13. Polarimetric SAR Interferometry based modeling for tree height and aboveground biomass retrieval in a tropical deciduous forest

    Science.gov (United States)

    Kumar, Shashi; Khati, Unmesh G.; Chandola, Shreya; Agrawal, Shefali; Kushwaha, Satya P. S.

    2017-08-01

    The regulation of the carbon cycle is a critical ecosystem service provided by forests globally. It is, therefore, necessary to have robust techniques for speedy assessment of forest biophysical parameters at the landscape level. It is arduous and time taking to monitor the status of vast forest landscapes using traditional field methods. Remote sensing and GIS techniques are efficient tools that can monitor the health of forests regularly. Biomass estimation is a key parameter in the assessment of forest health. Polarimetric SAR (PolSAR) remote sensing has already shown its potential for forest biophysical parameter retrieval. The current research work focuses on the retrieval of forest biophysical parameters of tropical deciduous forest, using fully polarimetric spaceborne C-band data with Polarimetric SAR Interferometry (PolInSAR) techniques. PolSAR based Interferometric Water Cloud Model (IWCM) has been used to estimate aboveground biomass (AGB). Input parameters to the IWCM have been extracted from the decomposition modeling of SAR data as well as PolInSAR coherence estimation. The technique of forest tree height retrieval utilized PolInSAR coherence based modeling approach. Two techniques - Coherence Amplitude Inversion (CAI) and Three Stage Inversion (TSI) - for forest height estimation are discussed, compared and validated. These techniques allow estimation of forest stand height and true ground topography. The accuracy of the forest height estimated is assessed using ground-based measurements. PolInSAR based forest height models showed enervation in the identification of forest vegetation and as a result height values were obtained in river channels and plain areas. Overestimation in forest height was also noticed at several patches of the forest. To overcome this problem, coherence and backscatter based threshold technique is introduced for forest area identification and accurate height estimation in non-forested regions. IWCM based modeling for forest

  14. Ship Discrimination Using Polarimetric SAR Data and Coherent Time-Frequency Analysis

    Directory of Open Access Journals (Sweden)

    Canbin Hu

    2013-12-01

    Full Text Available This paper presents a new approach for the discrimination of ship responses using polarimetric SAR (PolSAR data. The PolSAR multidimensional information is analyzed using a linear Time-Frequency (TF decomposition approach, which permits to describe the polarimetric behavior of a ship and its background area for different azimuthal angles of observation and frequencies of illumination. This paper proposes to discriminate ships from their background by using characteristics of their polarimetric TF responses, which may be associated with the intrinsic nature of the observed natural or artificial scattering structures. A statistical descriptor related to polarimetric coherence of the signal in the TF domain is proposed for detecting ships in different complex backgrounds, including SAR azimuth ambiguities, artifacts, and small natural islands, which may induce numerous false alarms. Choices of the TF analysis direction, i.e., along separate azimuth or range axis, or simultaneously in both directions, are investigated and evaluated. TF decomposition modes including range direction perform better in terms of discriminating ships from range focusing artifacts. In comparison with original full-resolution polarimetric indicators, the proposed TF polarimetric coherence descriptor is shown to qualitatively enhance the ship/background contrast and improve discrimination capabilities. Using polarimetric RADARSAT-2 data acquired over complex scenes, experimental results demonstrate the efficiency of this approach in terms of ship location retrieval and response characterization.

  15. Multi-Frequency Polarimetric SAR Classification Based on Riemannian Manifold and Simultaneous Sparse Representation

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2015-07-01

    Full Text Available Normally, polarimetric SAR classification is a high-dimensional nonlinear mapping problem. In the realm of pattern recognition, sparse representation is a very efficacious and powerful approach. As classical descriptors of polarimetric SAR, covariance and coherency matrices are Hermitian semidefinite and form a Riemannian manifold. Conventional Euclidean metrics are not suitable for a Riemannian manifold, and hence, normal sparse representation classification cannot be applied to polarimetric SAR directly. This paper proposes a new land cover classification approach for polarimetric SAR. There are two principal novelties in this paper. First, a Stein kernel on a Riemannian manifold instead of Euclidean metrics, combined with sparse representation, is employed for polarimetric SAR land cover classification. This approach is named Stein-sparse representation-based classification (SRC. Second, using simultaneous sparse representation and reasonable assumptions of the correlation of representation among different frequency bands, Stein-SRC is generalized to simultaneous Stein-SRC for multi-frequency polarimetric SAR classification. These classifiers are assessed using polarimetric SAR images from the Airborne Synthetic Aperture Radar (AIRSAR sensor of the Jet Propulsion Laboratory (JPL and the Electromagnetics Institute Synthetic Aperture Radar (EMISAR sensor of the Technical University of Denmark (DTU. Experiments on single-band and multi-band data both show that these approaches acquire more accurate classification results in comparison to many conventional and advanced classifiers.

  16. Distributed transverse stress measurement along an optic fiber using polarimetric OFDR.

    Science.gov (United States)

    Wei, Changjiang; Chen, Hongxin; Chen, Xiaojun; Chen, David; Li, Zhihong; Yao, X Steve

    2016-06-15

    We report a novel polarimetric optical frequency domain reflectometer (P-OFDR) that can simultaneously measure both space-resolved transverse stresses and light back-reflections along an optic fiber with sub-mm spatial resolution. By inducing transversal stresses and optical back-reflections at multiple points along a length of optic fiber, we demonstrate that our system can unambiguously distinguish the stresses from the back-reflections of a fiber with a fiber length longer than 800 m, a spatial resolution of 0.5 mm, a maximum stress level of up to 200 kpsi (1379 Mpa), a minimum stress of about 10 kpsi (69 Mpa), and a stress measurement uncertainty of 10%. We show that our P-OFDR can clearly identify the locations and magnitudes of the stresses inside a fiber coil induced during a fiber winding process. The P-OFDR can be used for fiber health monitoring for critical fiber links, fiber gyro coil characterization, and other distributed fiber sensing applications.

  17. Semi-Supervised Learning for Ill-Posed Polarimetric SAR Classification

    Directory of Open Access Journals (Sweden)

    Stefan Uhlmann

    2014-05-01

    Full Text Available In recent years, the interest in semi-supervised learning has increased, combining supervised and unsupervised learning approaches. This is especially valid for classification applications in remote sensing, while the data acquisition rate in current systems has become fairly large considering high- and very-high resolution data; yet on the other hand, the process of obtaining the ground truth data may be cumbersome for such large repositories. In this paper, we investigate the application of semi-supervised learning approaches and particularly focus on the small sample size problem. To that extend, we consider two basic unsupervised approaches by enlarging the initial labeled training set as well as an ensemble-based self-training method. We propose different strategies within self-training on how to select more reliable candidates from the pool of unlabeled samples to speed-up the learning process and to improve the classification performance of the underlying classifier ensemble. We evaluate the effectiveness of the proposed semi-supervised learning approach over polarimetric SAR data. Results show that the proposed self-training approach using an ensemble-based classifier that is initially trained over a small training set can achieve a similar performance level of a fully supervised learning approach where the training is performed over significantly larger labeled data. Considering the difficulties of the manual data labeling in such massive volumes of SAR repositories, this is indeed a promising accomplishment for semi-supervised SAR classification.

  18. Algorithm for wind speed estimate with polarimetric radar

    Directory of Open Access Journals (Sweden)

    Ю. А. Авер’янова

    2013-07-01

    Full Text Available The connection of wind speed and drops behavior is substantiated as well as the drop behavior influence onto the polarization characteristics of electromagnetic waves. The expression to calculate the wind speed taking into account the Weber number for the critical regime of drop deformation is obtained. The critical regime of drop deformation is the regime when drop is divided into two parts. The dependency of critical wind speed on the drop diameter is calculated and shown. The concept o polarization spectrum that is introduced in the previous papers is used to estimate the dynamic processes in the atmosphere. At the moment when the drop is under the influence of the wind that is equal to the critical wind speed the drop will be divided into two parts. This process will be reflected as the appearance of the two equal components of polarization spectra of reflected electromagnetic waves at the orthogonal antennas of Doppler Polarimetric Radar. Owing the information about the correspondence of the polarization component energy level to the drop diameter it is possible to estimate the wind speed with the obtained dependency. The process of the wind speed estimate with polarimetric radar is presented with the developed common algorithm

  19. Heavy Rainfall Monitoring by Polarimetric C-Band Weather Radars

    Directory of Open Access Journals (Sweden)

    Roberto Cremonini

    2010-11-01

    Full Text Available Piemonte region, in the north-western Italy, is characterized by complex orography and Mediterranean influence that often causes extreme rainfall event, during the warm season. Although the region is monitored by a dense gauge network (more than one gauge per 100 km2, the ground measurements are often inadequate to properly observe intense and highly variable precipitations. Polarimetric weather radars provide a unique way to monitor rainfall over wide areas, with the required spatial detail and temporal resolution. Nevertheless, most European weather radar networks are operating at C-band, which may seriously limit quantitative precipitation estimation in heavy rainfall due to relevant power signal attenuation. Phase measurements, unlike power measurements, are not affected by signal attenuation. For this reason, polarimetric radars, for which the differential phase shift measurements are available, provide an additional way in which to estimate precipitation, which is immune to signal attenuation. In this work differential phase based rainfall estimation techniques are applied to analyze two flash-floods: the first one occurred on the Ligurian Apennines on 16 August 2006 and the second occurred on 13 September 2008, causing rain accumulations above 270 mm in few hours.

  20. REMOVAL OF SPECTRO-POLARIMETRIC FRINGES BY TWO-DIMENSIONAL PATTERN RECOGNITION

    International Nuclear Information System (INIS)

    Casini, R.; Judge, P. G.; Schad, T. A.

    2012-01-01

    We present a pattern-recognition-based approach to the problem of the removal of polarized fringes from spectro-polarimetric data. We demonstrate that two-dimensional principal component analysis can be trained on a given spectro-polarimetric map in order to identify and isolate fringe structures from the spectra. This allows us, in principle, to reconstruct the data without the fringe component, providing an effective and clean solution to the problem. The results presented in this paper point in the direction of revising the way that science and calibration data should be planned for a typical spectro-polarimetric observing run.

  1. Three Genes That Affect Sugar Sensing (Abscisic Acid Insensitive 4, Abscisic Acid Insensitive 5, and Constitutive Triple Response 1) Are Differentially Regulated by Glucose in Arabidopsis1

    Science.gov (United States)

    Arroyo, Analilia; Bossi, Flavia; Finkelstein, Ruth R.; León, Patricia

    2003-01-01

    Mutant characterization has demonstrated that ABI4 (Abscisic Acid [ABA] Insensitive 4), ABI5 (ABA Insensitive 5), and CTR1 (Constitutive Triple Response 1) genes play an important role in the sugar signaling response in plants. The present study shows that the transcripts of these three genes are modulated by glucose (Glc) independently of the developmental arrest caused by high Glc concentrations. ABI4 and ABI5 transcripts accumulate in response to sugars, whereas the CTR1 transcript is transiently reduced followed by a rapid recovery. The results of our kinetic studies on gene expression indicate that ABI4, ABI5, and CTR1 are regulated by multiple signals including Glc, osmotic stress, and ABA. However, the differential expression profiles caused by these treatments suggest that distinct signaling pathways are used for each signal. ABI4 and ABI5 response to the Glc analog 2-deoxy-Glc supports this conclusion. Glc regulation of ABI4 and CTR1 transcripts is dependent on the developmental stage. Finally, the Glc-mediated regulation of ABI4 and ABI5 is affected in mutants displaying Glc-insensitive phenotypes such as gins, abas, abi4, abi5, and ctr1 but not in abi1-1, abi2-1, and abi3-1, which do not show a Glc-insensitive phenotype. The capacity of transcription factors, like the ones analyzed in this work, to be regulated by a variety of signals might contribute to the ability of plants to respond in a flexible and integral way to continuous changes in the internal and external environment. PMID:12970489

  2. Classification of Forest Regrowth Stage using Polarimetric Decomposition and Foliage Projective Cover

    Science.gov (United States)

    Clewley, D.; Lucas, R.; Bunting, P.; Moghaddam, M.

    2012-12-01

    Within Queensland, Australia extensive clearing of vegetation for agriculture has occurred within the Brigalow Belt Bioregion (BBB), reducing forests dominated by Acacia harpophylla (brigalow) to 10 % of their former extent. Where cleared land is left abandoned or unmanaged regeneration is rapid, Regenerating vegetation represents a more efficient and cost effective method for carbon sequestration than direct planting and offers a number of benefits over plantation forest, particularly in terms of provision of habitat for native fauna. To effectively protect regenerating vegetation, maps of the distribution of forests at different stages of regeneration are required. Whilst mapping approaches have traditionally focused on optical data, the high canopy cover of brigalow regrowth in all but the very early stages limits discrimination of forests at different stages of growth. The combination of optical data, namely Landsat derived Foliage Projective Cover (FPC) and Advanced Land Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (SAR) backscatter data have previously been investigated for mapping regrowth. This study therefore aimed to investigate the potential of the alpha-Entropy (α/H) decomposition (S Cloude and E Pottier, "An entropy based classification scheme for land applications of polarimetric SAR," 1997, IEEE Transactions on Geoscience and Remote Sensing, vol. 35, no. 1, pp. 68-78) applied to polarimetric ALOS PALSAR backscatter for mapping regrowth stage combined with FPC data to account for canopy variations. The study focused on the Tara Downs subregion, located in the Western Darling Downs, within the south of the BBB. PALSAR data were acquired over the study site in fully-polarimetric mode (incidence angle mid swath ~ 26 degrees). From these data α/H layers were generated and stacked with FPC data. Considering only those areas known to contain brigalow prior to clearing and with an FPC > 9 %, k-means clustering was applied, with

  3. Glucokinase, the pancreatic glucose sensor, is not the gut glucose sensor

    DEFF Research Database (Denmark)

    Murphy, R; Tura, A; Clark, P M

    2008-01-01

    measured at five time-points during a 75 g OGTT in 49 participants having GCK mutations with those of 28 familial controls. Mathematical modelling of glucose, insulin and C-peptide was used to estimate basal insulin secretion rate (BSR), total insulin secretion (TIS), beta cell glucose sensitivity....../INTERPRETATION: Glucokinase, the major pancreatic glucose sensor, is not the main gut glucose sensor. By modelling OGTT data in GCK mutation carriers we were able to distinguish a specific beta cell glucose-sensing defect. Our data suggest a reduction in potentiation of insulin secretion by glucose that is independent......AIMS/HYPOTHESIS: The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotrophic peptide (GIP) are released from intestinal endocrine cells in response to luminal glucose. Glucokinase is present in these cells and has been proposed as a glucose sensor. The physiological...

  4. A MEMS differential viscometric sensor for affinity glucose detection in continuous glucose monitoring

    International Nuclear Information System (INIS)

    Huang, Xian; Cai, Haogang; Song, Bing; Lin, Qiao; Li, Siqi; Davis, Erin; Wang, Qian; Leduc, Charles; Ravussin, Yann; Leibel, Rudolph; Li, Dachao; Accili, Domenico

    2013-01-01

    Micromachined viscometric affinity glucose sensors have been previously demonstrated using vibrational cantilever and diaphragm. These devices featured a single glucose detection module that determines glucose concentrations through viscosity changes of glucose-sensitive polymer solutions. However, fluctuations in temperature and other environmental parameters might potentially affect the stability and reliability of these devices, creating complexity in their applications in subcutaneously implanted continuous glucose monitoring (CGM). To address these issues, we present a MEMS differential sensor that can effectively reject environmental disturbances while allowing accurate glucose detection. The sensor consists of two magnetically driven vibrating diaphragms situated inside microchambers filled with a boronic-acid based glucose-sensing solution and a reference solution insensitive to glucose. Glucose concentrations can be accurately determined by characteristics of the diaphragm vibration through differential capacitive detection. Our in vitro and preliminary in vivo experimental data demonstrate the potential of this sensor for highly stable subcutaneous CGM applications. (paper)

  5. CAMEX-4 MOBILE X-BAND POLARIMETRIC WEATHER RADAR V1

    Data.gov (United States)

    National Aeronautics and Space Administration — Mobile X-band Polarimetric Weather Radar on Wheels (X-POW)is a Doppler scanning radar operating at 9.3 GHz.with horizontal and vertical polarization. Used for...

  6. GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar OLYMPEX V2

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar OLYMPEX V2 dataset consists of rain rate, reflectivity, Doppler velocity, and other...

  7. GPM GROUND VALIDATION NASA S-BAND DUAL POLARIMETRIC (NPOL) DOPPLER RADAR IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-Band Dual Polarimetric (NPOL) Doppler Radar IFloodS data set was collected from April 30, 2013 to June 16, 2013 near Traer, Iowa as...

  8. GPM GROUND VALIDATION IOWA X-BAND POLARIMETRIC MOBILE DOPPLER WEATHER RADARS IFLOODS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation Iowa X-band Polarimetric Mobile Doppler Weather Radars IFloodS dataset was gathered during the IFloodS campaign from April to June 2013...

  9. CLPX-Airborne: Polarimetric Ku-Band Scatterometer (POLSCAT) Data, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains Ku-band polarimetric scatterometer (POLSCAT) data collected as part of the Cold Land Processes Field Experiment (CLPX) to enable the...

  10. GPM Ground Validation NOAA X-band Polarimetric Radar (NOXP) IPHEx V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NOAA X-band dual-Polarimetric radar (NOXP) IPHEx dataset consists of differential reflectivity, differential phase shift, co-polar cross...

  11. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    OpenAIRE

    Raupach, Timothy H.; Berne, Alexis

    2016-01-01

    A new technique for estimating the raindrop size distribution (DSD) from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observation...

  12. Estimating soil moisture using the Danish polarimetric SAR

    DEFF Research Database (Denmark)

    Jiankang, Ji; Thomsen, A.; Skriver, Henning

    1995-01-01

    The results of applying data from the Danish polarimetric SAR (EMISAR) to estimate soil moisture for bare fields are presented. Fully calibrated C-band SAR images for hh, vv and cross polarizations have been used in this study. The measured surface roughness data showed that classical roughness...... autocorrelation functions (Gaussian and Exponential) were not able to fit natural surfaces well. A Gauss-Exp hybrid model which agreed better with the measured data has been proposed. Theoretical surface scattering models (POM, IEM), as well as an empirical model for retrieval of soil moisture and surface rms...... height from coand cross-polarized ratio, have been examined, but the results are less satisfactory. As soil moisture response to backscattering coefficient σo is mainly coupled to surface roughness effect for bare fields, a bilinear model coupling volumetric soil moisture mv and surface rms height σ...

  13. Scattering Mechanism Identification Based on Polarimetric HRRP of Manmade Target

    Directory of Open Access Journals (Sweden)

    Wu Jiani

    2016-04-01

    Full Text Available In this paper, we analyze the space polarization and frequency dispersion characteristics of the polarimetric High Resolution Range Profile (HRRP of manmade targets. We integrate these characteristics and propose a novel scheme for scattering mechanism identification. Using a polarization decomposition technique, the scheme first identifies the scattering mechanism of the scattering centers. Specially, it uses an algorithm to compensate for the polarization orientation angle in order to decrease the errors in judgment caused by the varying azimuth. Then, based on the frequency dispersion characteristics, we design threedimensional parameters to discriminate between the scattering centers, in order to decrease the inaccuracy in the discriminations. Finally, we conduct simulations based on electromagnetic data to validate the feasibility of the proposed scheme and to demonstrate that it provides a basis for practical use in target recognition.

  14. Classification of Polarimetric SAR Data Using Dictionary Learning

    DEFF Research Database (Denmark)

    Vestergaard, Jacob Schack; Nielsen, Allan Aasbjerg; Dahl, Anders Lindbjerg

    2012-01-01

    This contribution deals with classification of multilook fully polarimetric synthetic aperture radar (SAR) data by learning a dictionary of crop types present in the Foulum test site. The Foulum test site contains a large number of agricultural fields, as well as lakes, forests, natural vegetation......, grasslands and urban areas, which make it ideally suited for evaluation of classification algorithms. Dictionary learning centers around building a collection of image patches typical for the classification problem at hand. This requires initial manual labeling of the classes present in the data and is thus...... a method for supervised classification. Sparse coding of these image patches aims to maintain a proficient number of typical patches and associated labels. Data is consecutively classified by a nearest neighbor search of the dictionary elements and labeled with probabilities of each class. Each dictionary...

  15. Analytical Aspects of Total Starch Polarimetric Determination in Some Cereals

    Directory of Open Access Journals (Sweden)

    Rodica Caprita

    2016-10-01

    Full Text Available Starch is the most important digestible polysaccharide present in foods and feeds. The starch concentration in cereals cannot be determined directly, because the starch is contained within a structurally and chemically complex matrix. Fine grinding and boiling in dilute HCl are preparative steps necessary for complete release of the starch granules from the protein matrix. Starch can be determined using simple and inexpensive physical methods, such as density, refractive index or optical rotation assessment. The polarimetric method allows the determination even of small starch contents due to its extremely high specific rotation. For more accurate results, the contribution of free sugars is eliminated by dissolution in 40% (V/V ethanol. The influence of other optically active substances, which might interfere, is removed by filtration/clarification prior to the optical rotation measurement.

  16. Segment-based change detection for polarimetric SAR data

    DEFF Research Database (Denmark)

    Skriver, Henning; Nielsen, Allan Aasbjerg; Conradsen, Knut

    2006-01-01

    single-channel SAR images but multi-channel algorithms have also been described. Different approaches have been used for image segmentation. Edge detection combined with region growing is one approach, where segments are created by growing regions from a previously edge detected and edge thinned image....... This method relies primarily on a robust edge detector, which preferably provides a constant false alarm rate. For single-channel SAR images this is fulfilled by the ratio edge detector, and for polarimetric SAR data, an edge detector based on the above mentioned test statistic fulfils this. Another approach......, wetlands, lakes, and urban areas. Also, other test sites over for instance urban areas have been used to assess the improvement by the segment-based change detection method. In the paper, results from pixel-based change detection, i.e. without segmentation, and from segment-based change detection, where...

  17. Nearest-Regularized Subspace Classification for PolSAR Imagery Using Polarimetric Feature Vector and Spatial Information

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2017-11-01

    Full Text Available Feature extraction using polarimetric synthetic aperture radar (PolSAR images is of great interest in SAR classification, no matter if it is applied in an unsupervised approach or a supervised approach. In the supervised classification framework, a major group of methods is based on machine learning. Various machine learning methods have been investigated for PolSAR image classification, including neural network (NN, support vector machine (SVM, and so on. Recently, representation-based classifications have gained increasing attention in hyperspectral imagery, such as the newly-proposed sparse-representation classification (SRC and nearest-regularized subspace (NRS. These classifiers provide excellent performance that is comparable to or even better than the classic SVM for remotely-sensed image processing. However, rare studies have been found to extend this representation-based NRS classification into PolSAR images. By the use of the NRS approach, a polarimetric feature vector-based PolSAR image classification method is proposed in this paper. The polarimetric SAR feature vector is constructed by the components of different target decomposition algorithms for each pixel, including those scattering components of Freeman, Huynen, Krogager, Yamaguchi decomposition, as well as the eigenvalues, eigenvectors and their consequential parameters such as entropy, anisotropy and mean scattering angle. Furthermore, because all these representation-based methods were originally designed to be pixel-wise classifiers, which only consider the separate pixel signature while ignoring the spatial-contextual information, the Markov random field (MRF model is also introduced in our scheme. MRF can provide a basis for modeling contextual constraints. Two AIRSAR data in the Flevoland area are used to validate the proposed classification scheme. Experimental results demonstrate that the proposed method can reach an accuracy of around 99 % for both AIRSAR data by

  18. Polarimetric Radar Retrievals in Southeast Texas During Hurricane Harvey

    Science.gov (United States)

    Wolff, D. B.; Petersen, W. A.; Tokay, A.; Marks, D. A.; Pippitt, J. L.; Kirstetter, P. E.

    2017-12-01

    Hurricane Harvey hit the Texas Gulf Coast as a major hurricane on August 25, 2017 before exiting the state as a tropical storm on September 1, 2017. In its wake, it left a flood of historic proportions, with some areas measuring 60 inches of rain over a five-day period. Although the storm center stayed west of the immediate Houston area training bands of precipitation impacted the Houston area for five full days. The National Weather Service (NWS) WSR88D dual-polarimetric radar (KHGX), located southeast of Houston, maintained operations for the entirety of the event. The Harris County Flood Warning System (HCFWS) had 150 rain gauges deployed in its network and seven NWS Automated Surface Observing Systems (ASOS) rain gauges are also located in the area. In this study, we used the full radar data set to retrieve daily and event-total precipitation estimates within 120 km of the KHGX radar for the period August 25-29, 2017. These estimates were then compared to the HCFWS and ASOS gauges. Three different polarimetric hybrid rainfall retrievals were used: Ciffeli et al. 2011; Bringi et al. 2004; and, Chen et al. 2017. Each of these hybrid retrievals have demonstrated robust performance in the past. However, both daily and event-total comparisons from each of these retrievals compared to those of HCFWS and ASOS rain gauge networks resulted in significant underestimates by the radar retrievals. These radar underestimates are concerning. Sources of error and variance will be investigated to understand the source of radar-gauge disagreement. One current hypothesis is that due to the large number of small drops often found in hurricanes, the differential reflectivity and specific differential phase are relatively small so that the hybrid algorithms use only the reflectivity/rain rate procedure (so called Z-R relationships), and hence rarely invoke the ZDR or KDP procedures. Thus, an alternative Z-R relationship must be invoked to retrieve accurate rain rate estimates.

  19. An improved method for polarimetric image restoration in interferometry

    Science.gov (United States)

    Pratley, Luke; Johnston-Hollitt, Melanie

    2016-11-01

    Interferometric radio astronomy data require the effects of limited coverage in the Fourier plane to be accounted for via a deconvolution process. For the last 40 years this process, known as `cleaning', has been performed almost exclusively on all Stokes parameters individually as if they were independent scalar images. However, here we demonstrate for the case of the linear polarization P, this approach fails to properly account for the complex vector nature resulting in a process which is dependent on the axes under which the deconvolution is performed. We present here an improved method, `Generalized Complex CLEAN', which properly accounts for the complex vector nature of polarized emission and is invariant under rotations of the deconvolution axes. We use two Australia Telescope Compact Array data sets to test standard and complex CLEAN versions of the Högbom and SDI (Steer-Dwedney-Ito) CLEAN algorithms. We show that in general the complex CLEAN version of each algorithm produces more accurate clean components with fewer spurious detections and lower computation cost due to reduced iterations than the current methods. In particular, we find that the complex SDI CLEAN produces the best results for diffuse polarized sources as compared with standard CLEAN algorithms and other complex CLEAN algorithms. Given the move to wide-field, high-resolution polarimetric imaging with future telescopes such as the Square Kilometre Array, we suggest that Generalized Complex CLEAN should be adopted as the deconvolution method for all future polarimetric surveys and in particular that the complex version of an SDI CLEAN should be used.

  20. Assessment of GF-3 Polarimetric SAR Data for Physical Scattering Mechanism Analysis and Terrain Classification.

    Science.gov (United States)

    Yin, Junjun; Yang, Jian; Zhang, Qingjun

    2017-12-01

    On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric SAR can fully characterize the backscatter property of targets, and thus it is of great interest to explore the physical scattering mechanisms of terrain types, which is very important in interpreting polarimetric SAR imagery and for its further usages in Earth observations. In this paper, focusing on target scattering characterization and feature extraction, we generalize the Δ α B / α B method, which was proposed under the reflection symmetric assumption, for the general backscatter process to account for both the reflection symmetry and asymmetry cases. Then, we evaluate the performances of physical scattering mechanism analysis methods for GF-3 polarimetric SAR imagery. Radarsat-2 data acquired over the same area is used for cross validation. Results show that GF-3 polarimetric SAR data has great potential for target characterization, especially for ocean area observation.

  1. HIGH-RESOLUTION LINEAR POLARIMETRIC IMAGING FOR THE EVENT HORIZON TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Chael, Andrew A.; Johnson, Michael D.; Narayan, Ramesh; Doeleman, Sheperd S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Wardle, John F. C. [Brandeis University, Physics Department, Waltham, MA 02454 (United States); Bouman, Katherine L., E-mail: achael@cfa.harvard.edu [Massachusetts Institute of Technology, Computer Science and Artificial Intelligence Laboratory, 32 Vassar Street, Cambridge, MA 02139 (United States)

    2016-09-20

    Images of the linear polarizations of synchrotron radiation around active galactic nuclei (AGNs) highlight their projected magnetic field lines and provide key data for understanding the physics of accretion and outflow from supermassive black holes. The highest-resolution polarimetric images of AGNs are produced with Very Long Baseline Interferometry (VLBI). Because VLBI incompletely samples the Fourier transform of the source image, any image reconstruction that fills in unmeasured spatial frequencies will not be unique and reconstruction algorithms are required. In this paper, we explore some extensions of the Maximum Entropy Method (MEM) to linear polarimetric VLBI imaging. In contrast to previous work, our polarimetric MEM algorithm combines a Stokes I imager that only uses bispectrum measurements that are immune to atmospheric phase corruption, with a joint Stokes Q and U imager that operates on robust polarimetric ratios. We demonstrate the effectiveness of our technique on 7 and 3 mm wavelength quasar observations from the VLBA and simulated 1.3 mm Event Horizon Telescope observations of Sgr A* and M87. Consistent with past studies, we find that polarimetric MEM can produce superior resolution compared to the standard CLEAN algorithm, when imaging smooth and compact source distributions. As an imaging framework, MEM is highly adaptable, allowing a range of constraints on polarization structure. Polarimetric MEM is thus an attractive choice for image reconstruction with the EHT.

  2. The ROHP-PAZ mission and the polarimetric and non-polarimetric effects of rain and other fozen hydrometeors on GNSS Radio-Occultation signals.

    Science.gov (United States)

    De La Torre Juarez, M.; Padulles, R.; Cardellach, E.; Tomás, S.; Turk, J.; Ao, C. O.; Oliveras, S.; Rius, A.

    2015-12-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) will test, for the first time, the new polarimetric radio occultation (RO) concept. This is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) RO payload on board of the Spanish Earth Observation satellite PAZ. The launch of the satellite is scheduled for October 2015, and it will be followed by a 6-month commissioning phase period and has an expected life of 7 years, with a goal of 10 years.The concept is similar to that used in some polarimetric weather radars: to measure the differential phase shift between the two polarimetric components of the received signal, although in this case we will use the forward scattering geometry instead of the backscattering one. It will allow us to retrieve precipitation and other hydrometeors information, and simultaneous thermodynamic vertical profiles which will help to the understanding of the thermodynamic processes beyond heavy rain events. A sensitivity analysis has been performed, showing that the rain-induced effect is above PAZ detectability threshold in 90% of the events with along-ray averaged rain rate higher than 5 mm/h. Also, a ground field campaign has been conducted prior to the launch of the satellite. The measurements from the campaign have shown the first experimental evidences that precipitation and frozen hydrometeors induce a noticeable effect into the polarimetric RO observables. We will present here the actual status of the mission and the results from the field campaign. We will also discuss the results of the theoretical study of the thermodynamics and the effects of rain and frozen hydrometeors into standard and polarimetric RO, based on a large collocation exercise of COSMIC and TerrasSar-X with TRMM, GPM and CloudSat.

  3. Glucose allostasis

    DEFF Research Database (Denmark)

    Stumvoll, Michael; Tataranni, P Antonio; Stefan, Norbert

    2003-01-01

    (insulin resistance), we propose to use the term "glucose allostasis." Allostasis (stability through change) ensures the continued homeostatic response (stability through staying the same) to acute stress at some cumulative costs to the system. With increasing severity and over time, the allostatic load......In many organisms, normoglycemia is achieved by a tight coupling of nutrient-stimulated insulin secretion in the pancreatic beta-cell (acute insulin response [AIR]) and the metabolic action of insulin to stimulate glucose disposal (insulin action [M]). It is widely accepted that in healthy...

  4. Fiber-based polarimetric stress sensor for measuring the Young's modulus of biomaterials

    Science.gov (United States)

    Harrison, Mark C.; Armani, Andrea M.

    2015-03-01

    Polarimetric optical fiber-based stress and pressure sensors have proven to be a robust tool for measuring and detecting changes in the Young's modulus (E) of materials in response to external stimuli, including the real-time monitoring of the structural integrity of bridges and buildings. These sensors typically work by using a pair of polarizers before and after the sensing region of the fiber, and often require precise alignment to achieve high sensitivity. The ability to perform similar measurements in natural and in engineered biomaterials could provide significant insights and enable research advancement and preventative healthcare. However, in order for this approach to be successful, it is necessary to reduce the complexity of the system by removing free-space components and the need for alignment. As the first step in this path, we have developed a new route for performing these measurements. By generalizing and expanding established theoretical analyses for these types of sensors, we have developed a predictive theoretical model. Additionally, by replacing the conventional free space components and polarization filters with a polarimeter, we have constructed a sensor system with higher sensitivity and which is semi-portable. In initial experiments, a series of polydimethylsiloxane (PDMS) samples with several base:curing agent ratios ranging from 5:1 up to 30:1 were prepared to simulate tissues with different stiffnesses. By simultaneously producing stress-strain curves using a load frame and monitoring the polarization change of light traveling through the samples, we verified the accuracy of our theoretical model.

  5. Electrochemical non-enzymatic glucose sensors

    International Nuclear Information System (INIS)

    Park, Sejin; Boo, Hankil; Chung, Taek Dong

    2006-01-01

    The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials

  6. Polarimetric Emission of Rain Events: Simulation and Experimental Results at X-Band

    Directory of Open Access Journals (Sweden)

    Nuria Duffo

    2009-06-01

    Full Text Available Accurate models are used today for infrared and microwave satellite radiance simulations of the first two Stokes elements in the physical retrieval, data assimilation etc. of surface and atmospheric parameters. Although in the past a number of theoretical and experimental works have studied the polarimetric emission of some natural surfaces, specially the sea surface roughened by the wind (Windsat mission, very limited studies have been conducted on the polarimetric emission of rain cells or other natural surfaces. In this work, the polarimetric emission (four Stokes elements of a rain cell is computed using the polarimetric radiative transfer equation assuming that raindrops are described by Pruppacher-Pitter shapes and that their size distribution follows the Laws-Parsons law. The Boundary Element Method (BEM is used to compute the exact bistatic scattering coefficients for each raindrop shape and different canting angles. Numerical results are compared to the Rayleigh or Mie scattering coefficients, and to Oguchi’s ones, showing that above 1-2 mm raindrop size the exact formulation is required to model properly the scattering. Simulation results using BEM are then compared to the experimental data gathered with a X-band polarimetric radiometer. It is found that the depolarization of the radiation caused by the scattering of non-spherical raindrops induces a non-zero third Stokes parameter, and the differential phase of the scattering coefficients induces a non-zero fourth Stokes parameter.

  7. Atmospheric polarimetric effects on GNSS radio occultations: the ROHP-PAZ field campaign

    Science.gov (United States)

    Padullés, R.; Cardellach, E.; de la Torre Juárez, M.; Tomás, S.; Turk, F. J.; Oliveras, S.; Ao, C. O.; Rius, A.

    2016-01-01

    This study describes the first experimental observations showing that hydrometeors induce polarimetric signatures in global navigation satellite system (GNSS) signals. This evidence is relevant to the PAZ low Earth orbiter, which will test the concept and applications of polarimetric GNSS radio occultation (RO) (i.e. ROs obtained with a dual-polarization antenna). A ground field campaign was carried out in preparation for PAZ to verify the theoretical sensitivity studies on this concept (Cardellach et al., 2015). The main aim of the campaign is to identify and understand the factors that might affect the polarimetric GNSS observables. Studied for the first time, GNSS signals measured with two polarimetric antennas (H, horizontal, and V, vertical) are shown to discriminate between heavy rain events by comparing the measured phase difference between the H and V phase delays (ΔΦ) in different weather scenarios. The measured phase difference indicates higher dispersion under rain conditions. When individual events are examined, significant increases in ΔΦ occur when the radio signals cross rain cells. Moreover, the amplitude of such a signal is much higher than the theoretical prediction for precipitation; thus, other sources of polarimetric signatures have been explored and identified. Modelling of other hydrometeors, such as melting particles and ice crystals, have been proposed to explain the obtained measurements, with good agreement in more than 90 % of the cases.

  8. Fitting a Two-Component Scattering Model to Polarimetric SAR Data

    Science.gov (United States)

    Freeman, A.

    1998-01-01

    Classification, decomposition and modeling of polarimetric SAR data has received a great deal of attention in the recent literature. The objective behind these efforts is to better understand the scattering mechanisms which give rise to the polarimetric signatures seen in SAR image data. In this Paper an approach is described, which involves the fit of a combination of two simple scattering mechanisms to polarimetric SAR observations. The mechanisms am canopy scatter from a cloud of randomly oriented oblate spheroids, and a ground scatter term, which can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, seen through a layer of vertically oriented scatterers. An advantage of this model fit approach is that the scattering contributions from the two basic scattering mechanisms can be estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. The model fit can be applied to polarimetric AIRSAR data at C-, L- and P-Band.

  9. Evaluation of Polarimetric SAR Decomposition for Classifying Wetland Vegetation Types

    Directory of Open Access Journals (Sweden)

    Sang-Hoon Hong

    2015-07-01

    Full Text Available The Florida Everglades is the largest subtropical wetland system in the United States and, as with subtropical and tropical wetlands elsewhere, has been threatened by severe environmental stresses. It is very important to monitor such wetlands to inform management on the status of these fragile ecosystems. This study aims to examine the applicability of TerraSAR-X quadruple polarimetric (quad-pol synthetic aperture radar (PolSAR data for classifying wetland vegetation in the Everglades. We processed quad-pol data using the Hong & Wdowinski four-component decomposition, which accounts for double bounce scattering in the cross-polarization signal. The calculated decomposition images consist of four scattering mechanisms (single, co- and cross-pol double, and volume scattering. We applied an object-oriented image analysis approach to classify vegetation types with the decomposition results. We also used a high-resolution multispectral optical RapidEye image to compare statistics and classification results with Synthetic Aperture Radar (SAR observations. The calculated classification accuracy was higher than 85%, suggesting that the TerraSAR-X quad-pol SAR signal had a high potential for distinguishing different vegetation types. Scattering components from SAR acquisition were particularly advantageous for classifying mangroves along tidal channels. We conclude that the typical scattering behaviors from model-based decomposition are useful for discriminating among different wetland vegetation types.

  10. Polarimetric study of the interstellar medium in Taurus Dark Clouds

    International Nuclear Information System (INIS)

    Hsu, J.

    1985-01-01

    An optical linear polarimetric survey was completed for more than 300 stars in an area of 6.5 0 x 10 0 toward the Taurus Dark Clouds Complex. It was found that the orientation of the magnetic field is roughly perpendicular to the elongation direction of the dust lanes, indicating cloud contraction along the magnetic field lines. The distance to the front edge of the dark clouds in Taurus is determined to be 126 pc. There is only insignificant amount of obscuring material between the cloud complex and the Sun. Besides the polarization data, the reddenings of about 250 stars were also obtained from the UBV photometry. The mean polarization to reddening ratio in the Taurus region is 4.6, which is similar to that of the general interstellar matter. The wavelengths of maximum polarization were determined for 30 stars in Taurus. They show an average value of lambda/sub max/ = 0.57 μm, which is only slightly higher than the mean value of the general interstellar medium, lambda/sub max/ = 0.55 μm. A few stars that show higher values of lambda/sub max/ are found near the small isolated regions of very high extinction. One such highly obscured small region where very complex long chain molecules have been discovered in the ratio spectra, is the Taurus Molecular Cloud 1

  11. Sample Extraction Bsaed on Helix Scattering for Polarimetric SAR Calibratio

    Science.gov (United States)

    Chang, Y.; Yang, J.; Li, P.; Zhao, L.; Shi, L.

    2017-09-01

    Polarimetric calibration (PolCAL) of Synthetic Aperture Radar (SAR) images is a significant preprocessing for further applications. Since the reflection symmetry property of distributed objects can provide stable constraints for PolCAL. It is reasonable to extract these reference samples before calibration. The helix scattering generally appears in complex urban area and disappears for a natural scatterer, making it a good measure to extract distributed objects. In this paper, a novel technique that extracts reflecting symmetry samples is proposed by using helix scattering. The helix scattering information is calculated by Yamaguchi four-component decomposition algorithm. An adaptive threshold selection algorithm based on generalized Gaussian distribution is also utilized to scale the helix scattering components automatically, getting rid of the problem of various numerical range. The extracting results will be taken as PolCAL reference samples and the Quegan method are utilized to calibrate these PolSAR images. A C-band airborne PolSAR data was taken as examples to evaluate its ability in improving calibration precision. Traditional method i.e. extracting samples with span power was also evaluated as contrast experiment. The results showed that the samples extracting method based on helix scattering can improve the Polcal precision preferably.

  12. Status of PEM-based polarimetric MSE development at KSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jinseok; Chung, Jinil; Oh, Seungtae; Ko, Wonha [National Fusion Research Institute, Daejeon (Korea, Republic of); Bock, Maarten de; Ong, Henry; Lange, Guido [Eindhoven University of Technology, Eindhoven (Netherlands)

    2014-10-15

    A multi-chord PEM (photo elastic modulator)-based polarimetric motional Stark effect (MSE) system is under development for the KSTAR tokamak. The conceptual design for the front optics was optimized to preserve not only the polarization state of the input light for the MSE measurements but also the signal intensity of the existing charge exchange spectroscopy (CES) system that will share the front optics with the MSE. The optics design incorporates how to determine the number of channels and the number of fibers for each channel. A dielectric coating will be applied on the mirror to minimize the relative reflectivity and the phase shift between the two orthogonal polarization components of the incident light. Lenses with low stress-birefringence constants will be adopted to minimize non-linear and random changes in the polarization through the lenses, which is a trade-off with the rather high Faraday rotation in the lenses because the latter effect is linear and can be relatively easily calibrated out. Intensive spectrum measurements and their comparisons with the simulated spectra are done to assist the design of the bandpass filter system that will also use tilting stages to remotely control the passband. Following the system installation in 2014, the MSE measurements are expected to be performed during the 2015 KSTAR campaign.

  13. SAMPLE EXTRACTION BSAED ON HELIX SCATTERING FOR POLARIMETRIC SAR CALIBRATIO

    Directory of Open Access Journals (Sweden)

    Y. Chang

    2017-09-01

    Full Text Available Polarimetric calibration (PolCAL of Synthetic Aperture Radar (SAR images is a significant preprocessing for further applications. Since the reflection symmetry property of distributed objects can provide stable constraints for PolCAL. It is reasonable to extract these reference samples before calibration. The helix scattering generally appears in complex urban area and disappears for a natural scatterer, making it a good measure to extract distributed objects. In this paper, a novel technique that extracts reflecting symmetry samples is proposed by using helix scattering. The helix scattering information is calculated by Yamaguchi four-component decomposition algorithm. An adaptive threshold selection algorithm based on generalized Gaussian distribution is also utilized to scale the helix scattering components automatically, getting rid of the problem of various numerical range. The extracting results will be taken as PolCAL reference samples and the Quegan method are utilized to calibrate these PolSAR images. A C-band airborne PolSAR data was taken as examples to evaluate its ability in improving calibration precision. Traditional method i.e. extracting samples with span power was also evaluated as contrast experiment. The results showed that the samples extracting method based on helix scattering can improve the Polcal precision preferably.

  14. Modeling the photo-polarimetric characteristics of brown dwarfs

    Science.gov (United States)

    Sanghavi, Suniti; Millar-Blanchaer, Max; Jensen-Clem, Rebecca; Shporer, Avi; Nilsson, Ricky; Tinyanont, Samaporn; Riedel, Adric; Kataria, Tiffany; Mawet, Dimitri

    2018-01-01

    An envelope of scatterers like free electrons, atoms/molecules, or haze/clouds affect the Stokes vector of radiation emitted by an oblate body.Due to their high rotation rates, brown dwarfs (BDs) are often considerably oblate. We present a conics-based radiative transfer (RT) scheme for computing the disc-resolved and disc-integrated polarized emission of an oblate body like a BD or extrasolar giant planet (EGP) bearing homogenous or patchy clouds. Using this capability, we theoretically examine the photo-polarimetric signal of BDs as a function of the scattering properties of its atmosphere like cloud optical thickness and grain size concurrently with BD properties like oblateness and inclination angle. The effect of oblateness is examined with and without the temperature gradients caused by gravitational darkening, revealing that the latter can considerably amplify the disc-integrated polarization. The signal depends on both oblateness and inclination angle, with the degree of polarization (DoP) increasing with oblateness and decreasing with inclination, a property useful for assessing the exact spatial orientation of the rotation axis in favorable cases. Our examination of BD cloud properties shows a relative blue-shift in the near-infrared (NIR) for increasing droplet size in optically thick clouds - interesting in view of the observed relative brightening in the J-band for L/T transition BDs. For large cloud grains, the polarization decreases sharply, while the transmitted intensity shows a steady increase, thus reducing the DoP.

  15. Neuroscience of glucose homeostasis

    NARCIS (Netherlands)

    La Fleur, S E; Fliers, E; Kalsbeek, A

    2014-01-01

    Plasma glucose concentrations are homeostatically regulated and maintained within strict boundaries. Several mechanisms are in place to increase glucose output when glucose levels in the circulation drop as a result of glucose utilization, or to decrease glucose output and increase tissue glucose

  16. Quantitative Estimation of Above Ground Crop Biomass using Ground-based, Airborne and Spaceborne Low Frequency Polarimetric Synthetic Aperture Radar

    Science.gov (United States)

    Koyama, C.; Watanabe, M.; Shimada, M.

    2016-12-01

    Estimation of crop biomass is one of the important challenges in environmental remote sensing related to agricultural as well as hydrological and meteorological applications. Usually passive optical data (photographs, spectral data) operating in the visible and near-infrared bands is used for such purposes. The virtue of optical remote sensing for yield estimation, however, is rather limited as the visible light can only provide information about the chemical characteristics of the canopy surface. Low frequency microwave signals with wavelength longer 20 cm have the potential to penetrate through the canopy and provide information about the whole vertical structure of vegetation from the top of the canopy down to the very soil surface. This phenomenon has been well known and exploited to detect targets under vegetation in the military radar application known as FOPEN (foliage penetration). With the availability of polarimetric interferometric SAR data the use PolInSAR techniques to retrieve vertical vegetation structures has become an attractive tool. However, PolInSAR is still highly experimental and suitable data is not yet widely available. In this study we focus on the use of operational dual-polarization L-band (1.27 GHz) SAR which is since the launch of Japan's Advanced Land Observing Satellite (ALOS, 2006-2011) available worldwide. Since 2014 ALOS-2 continues to deliver such kind of partial polarimetric data for the entire land surface. In addition to these spaceborne data sets we use airborne L-band SAR data acquired by the Japanese Pi-SAR-L2 as well as ultra-wideband (UWB) ground based SAR data operating in the frequency range from 1-4 GHz. By exploiting the complex dual-polarization [C2] Covariance matrix information, the scattering contributions from the canopy can be well separated from the ground reflections allowing for the establishment of semi-empirical relationships between measured radar reflectivity and the amount of fresh-weight above

  17. Estimation and Removing of Anisotropic Scattering for Multiaspect Polarimetric SAR Image

    Directory of Open Access Journals (Sweden)

    Li Yang

    2015-06-01

    Full Text Available Multiaspect Synthetic Aperture Radar (SAR can generate high resolution images and target scattering signatures in different azimuth angles from the coherent integration of all subaperture images. However, mixed anisotropic scatters limit the application of traditional imaging theory. Anisotropic scattering may introduce errors in polarimetric parameters by decreasing the reliability of terrain classification and detection of variability. Thus a method is proposed for estimating and removing anisotropic scattering in multiaspect polarimetric SAR images. The proposed algorithm is based on the maximum likelihood and likelihood-ratio tests for the two-class case, while considering the speckle effect, the mechanism of removing the anisotropic scattering, and the monotonicity of the Constant False Alarm Rate (CFAR detection function. We compare the polarimetric entropy before and after removing the anisotropic subapertures, and then validate the algorithm's potential in retrieving the target signature using a P-band quad-pol airborne SAR with circular trajectory.

  18. Fast polarimetric dehazing method for visibility enhancement in HSI colour space

    Science.gov (United States)

    Zhang, Wenfei; Liang, Jian; Ren, Liyong; Ju, Haijuan; Bai, Zhaofeng; Wu, Zhaoxin

    2017-09-01

    Image haze removal has attracted much attention in optics and computer vision fields in recent years due to its wide applications. In particular, the fast and real-time dehazing methods are of significance. In this paper, we propose a fast dehazing method in hue, saturation and intensity colour space based on the polarimetric imaging technique. We implement the polarimetric dehazing method in the intensity channel, and the colour distortion of the image is corrected using the white patch retinex method. This method not only reserves the detailed information restoration capacity, but also improves the efficiency of the polarimetric dehazing method. Comparison studies with state of the art methods demonstrate that the proposed method obtains equal or better quality results and moreover the implementation is much faster. The proposed method is promising in real-time image haze removal and video haze removal applications.

  19. The Potential of Polarimetric and Compact SAR Data in Rice Identification

    International Nuclear Information System (INIS)

    Shao, Y; Li, K; Liu, L; Yang, Z; Brisco, B

    2014-01-01

    Rice is a major food staple in the world, and provides food for more than one-third of the global population. The monitoring and mapping of paddy rice in a timely and efficient manner is very important for governments and decision makers. Synthetic Aperture Radar (SAR) has been proved to be a significant data source in rice monitoring. In this study, RADARSAT-2 polarimetric data were used to simulate compact polarimetry data. The simulated compact data and polarimetric data were then used to evaluate the information content for rice identification. The results indicate that polarimetric SAR can be used for rice identification based on the scattering mechanisms. The compact polarization RH and the RH/RL ratio are very promising for the discrimination of transplanted rice and direct-sown rice. These results require verification in further research

  20. Polarimetric SAR Image Classification Using Multiple-feature Fusion and Ensemble Learning

    Directory of Open Access Journals (Sweden)

    Sun Xun

    2016-12-01

    Full Text Available In this paper, we propose a supervised classification algorithm for Polarimetric Synthetic Aperture Radar (PolSAR images using multiple-feature fusion and ensemble learning. First, we extract different polarimetric features, including extended polarimetric feature space, Hoekman, Huynen, H/alpha/A, and fourcomponent scattering features of PolSAR images. Next, we randomly select two types of features each time from all feature sets to guarantee the reliability and diversity of later ensembles and use a support vector machine as the basic classifier for predicting classification results. Finally, we concatenate all prediction probabilities of basic classifiers as the final feature representation and employ the random forest method to obtain final classification results. Experimental results at the pixel and region levels show the effectiveness of the proposed algorithm.

  1. A high resolution polarimetric L-band SAR-design and first results

    DEFF Research Database (Denmark)

    Skou, Niels; Granholm, Johan; Woelders, Kim

    1995-01-01

    An L-band polarimetric SAR system has been developed as part of the dual frequency (L- and C-band), polarimetric, airborne EMISAR system. The SAR features a unique combination of fine resolution (2×2 m) and wide swath (9.3 km). The transmitter power is 6 kW. From a flight altitude of 41,000 ft...... conventional PIN diode switch matrix able to sustain the 6 kW peak power from the transmitter still exhibiting low loss (0.3 dB) and high isolation (more than 50 dB). Thus system cross talk (between polarizations) is dominated by antenna cross talk and is some -35 dB. Polarimetric imagery has been acquired...

  2. Contribution of polarimetric imaging for the characterization of fibrous surface properties at different scales

    Science.gov (United States)

    Tourlonias, Michel; Bigué, Laurent; Bueno, Marie-Ange

    2010-01-01

    The point in using polarimetric imaging for surface characterization is highlighted in this paper. A method for the evaluation of nonwoven surface properties at microscopic and macroscopic scales is described. This method is based on a polarimetric apparatus and various image processing operations are then performed depending on the studied scale. Polarimetric imaging applied to nonwovens, particularly degree of polarization imaging, highlights texture inhomogeneities. At both scales, image processing techniques were designed to analyze surface zones of different textures. At the macroscopic scale, a basic image processing was developed in order to detect the nonwoven manufacturing process defects. Moreover at the microscopic scale, i.e. at the fiber scale, image processing was adapted to evaluate fiber orientation within nonwovens, which is known to be an important information for mechanical behavior prediction.

  3. Detection of buried pipes by polarimetric borehole radar; Polarimetric borehole radar ni yoru maisetsukan no kenshutsu jikken

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Niitsuma, H. [Tohoku University, Sendai (Japan); Nakauchi, T. [Osaka Gas Co. Ltd., Osaka (Japan)

    1997-05-27

    If the borehole radar is utilized for detection of buried pipes, the underground radar measurement becomes possible even in the situation where the mesurement on the earth surface is difficult, for example, such a place as under the road where there is much traffic. However, since buried pipes are horizontally installed and the existing borehole radar can send/receive only vertical polarization, the measurement conducted comes to be poor in efficiency from a viewpoint of the polarization utilization. Therefore, by introducing the polarimetric borehole radar to the detection of buried pipes, a basic experiment was conducted for the effective detection of horizontal buried pipes. Proposing the use of a slot antenna which can send/receive horizontal polarization in borehole in addition to a dipole antenna which sends/receives vertical polarization, developed was a step frequency type continuous wave radar of a network analyzer basis. As a result of the experiment, it was confirmed that reflection from buried pipes is largely dependent on polarization. Especially, it was found that in the slot dipole cross polarization mesurement, reflection from buried pipes can be emphasized. 4 refs., 5 figs.

  4. Airborne Ku-Band Polarimetric Radar Remote Sensing of Terrestrial Snow Cover

    Science.gov (United States)

    Yueh, Simon; Cline, Donald; Elder, Kelly

    2008-01-01

    Preliminary analyses of the POLSCAT data acquired from the CLPX-II in winter 2006-2007 are described in this paper. The data showed the response of the Ku-band radarechoes to snowpack changes for various types of background vegetation. We observed about 0.2 to 0.4 dB increases in backscatter for every 1 cm SWE accumulation for sage brush and agricultural fields. The co-polarized VV and HH radar resposnes are similar, while the corss-polarized (VH or HV) echoes showedgreater resposne to the change of SWE. The data also showed the impact of surface hoar growth and freeze/thaw cycles, whichcreated large snow grain sizes and ice lenses, respectively, and consequently increased the radar signals by a few dBs.

  5. Complex Wishart distribution based analysis of polarimetric synthetic aperture radar data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Skriver, Henning; Conradsen, Knut

    2007-01-01

    Multi-look, polarimetric synthetic aperture radar (SAR) data are often worked with in the so-called covariance matrix representation. For each pixel this representation gives a 3x3 Hermitian, positive definite matrix which follows a complex Wishart distribution. Based on this distribution a test ...... covering agricultural fields near Foulum, Denmark, are used. Soon the Japanese ALOS, the German TerraSAR-X and the Canadian RADARSAT-2 will acquire space-borne, polarimetric data making analysis based on these methods important....

  6. Comparison between Multitemporal and Polarimetric SAR Data for Land Cover Classification

    DEFF Research Database (Denmark)

    Skriver, Henning

    2008-01-01

    The investigation focuses on the determination of the land cover type using SAR data, including single polarisation, dual polarisation and fully polarimetric data, at L-band. The analysed data set was acquired during the AgriSAR 2006 campaign by the airborne ESAR system over the Gormin agricultural...... site (Northeast Germany). The multitemporal acquisitions significantly improve the classification results for single and dual polarization configurations. The best results for the single and dual polarization configurations are better than for the polarimetric mode. Overall, the cross...

  7. OPTICAL PHOTOMETRIC AND POLARIMETRIC INVESTIGATION OF NGC 1931

    International Nuclear Information System (INIS)

    Pandey, A. K.; Eswaraiah, C.; Sharma, Saurabh; Yadav, Ram Kesh; Samal, M. R.; Chauhan, N.; Chen, W. P.; Jose, J.; Ojha, D. K.; Chandola, H. C.

    2013-01-01

    We present optical photometric and polarimetric observations of stars toward NGC 1931 with the aim of deriving cluster parameters such as distance, reddening, age, and luminosity/mass function as well as understanding dust properties and star formation in the region. The distance to the cluster is found to be 2.3 ± 0.3 kpc and the reddening E(B – V) in the region is found to be variable. The stellar density contours reveal two clusters in the region. The observations suggest a differing reddening law within the cluster region. Polarization efficiency of the dust grains toward the direction of the cluster is found to be less than that for the general diffuse interstellar medium (ISM). The slope of the mass function (–0.98 ± 0.22) in the southern region in the mass range of 0.8 ☉ < 9.8 is found to be shallower in comparison to that in the northern region (–1.26 ± 0.23), which is comparable to the Salpeter value (–1.35). The K-band luminosity function (KLF) of the region is found to be comparable to the average value of the slope (∼0.4) for young clusters obtained by Lada and Lada; however, the slope of the KLF is steeper in the northern region as compared to the southern region. The region is probably ionized by two B2 main-sequence-type stars. The mean age of the young stellar objects (YSOs) is found to be 2 ± 1 Myr, which suggests that the identified YSOs could be younger than the ionizing sources of the region. The morphology of the region, the distribution and ages of the YSOs, and ionizing sources indicate a triggered star formation in the region.

  8. Microphysical Structures of Hurricane Irma Observed by Polarimetric Radar

    Science.gov (United States)

    Didlake, A. C.; Kumjian, M. R.

    2017-12-01

    This study examines dual-polarization radar observations of Hurricane Irma as its center passed near the WSR-88D radar in Puerto Rico, capturing needed microphysical information of a mature tropical cyclone. Twenty hours of observations continuously sampled the inner core precipitation features. These data were analyzed by annuli and azimuth, providing a bulk characterization of the primary eyewall, secondary eyewall, and rainbands as they varied around the storm. Polarimetric radar variables displayed distinct signatures of convective and stratiform precipitation in the primary eyewall and rainbands that were organized in a manner consistent with the expected kinematic asymmetry of a storm in weak environmental wind shear but with moderate low-level storm-relative flow. In the front quadrants of the primary eyewall, vertical profiles of differential reflectivity (ZDR) exhibit increasing values with decreasing height consistent with convective precipitation processes. In particular, the front-right quadrant exhibits a signature in reflectivity (ZH) and ZDR indicating larger, sparser drops, which is consistent with a stronger updraft present in this quadrant. In the rear quadrants, a sharply peaked ZDR maximum occurs within the melting layer, which is attributed of stratiform processes. In the rainbands, the convective to stratiform transition can be seen traveling from the front-right to the front-left quadrant. The front-right quadrant exhibits lower co-polar correlation coefficient (ρHV) values in the 3-8 km altitude layer, suggesting larger vertical spreading of various hydrometeors that occurs in convective vertical motions. The front-left quadrant exhibits larger ρHV values, suggesting less diversity of hydrometeor shapes, consistent with stratiform processes. The secondary eyewall did not exhibit a clear signature of processes preferred in a specific quadrant, and a temporal analysis of the secondary eyewall revealed a complex evolution of its structure

  9. OIL DETECTION IN A COASTAL MARSH WITH POLARIMETRIC SAR

    Directory of Open Access Journals (Sweden)

    E. Ramsey III

    2012-09-01

    Full Text Available The NASA UAVSAR was deployed June 2010 to support Deep Water Horizon oil spill response activities specifically, oil detection and characterization, oil extent mapping in wetlands, coastal resource impact detection, and ecosystem recovery. The UAVSAR platform demonstrated enhanced capability to act rapidly and provide targeted mapping response. Our research focused on the effectiveness of high spatial resolution and fully polarimetric L-band Synthetic Aperture Radar (PolSAR for mapping oil in wetlands, specifically within Barataria Bay in eastern coastal Louisiana. Barataria Bay contained a numerous site observations confirming spatially extensive shoreline oil impacts, multiple oil spill UAVSAR collections, and a near anniversary 2009 collection. PolSAR oil detection relied on decomposition and subsequent classifications of the single look complex (SLC calibrated radar cross sections representing the complex elements of the scattering matrix. Initial analyses results found that shoreline marsh structural damage as well as oil on marsh plants and sediments without canopy structural damage were exhibited as anomalous features on post-spill SLC scenes but were not evident on the pre-spill SLC scene collected in 2009. Pre-spill and post-spill Freeman-Durden (FD and Cloude-Pottier (CP decompositions and the Wishart classifications seeded with the FD and CP classes (Wishart-FD also highlighted these nearshore features as a change in dominate scatter from pre-spill to post-spill. SLC analyses also indicated penetration of oil ladened waters into interior marshes well past the immediate shorelines; however, these post-spill SLC analyses results could not be validated due to the lack of observational data and possible flooding in the pre-spill SLC scene.

  10. The Glucose-Insulin Control System

    DEFF Research Database (Denmark)

    Hallgreen, Christine Erikstrup; Korsgaard, Thomas Vagn; Hansen, RenéNormann N.

    2008-01-01

    are divided into smaller pieces and analyzed via several small biosimulation models that describe events in beta cells, liver, muscle and adipose tissue etc. In the glucose-sensing part, the beta cell are shown to have some characteristics of a classic PID controller, but with nonlinear properties....... Furthermore, the body has also glucose sensors in the intestine, the brain, the portal vein, and to some extent the liver, and they sense very different glucose concentrations. All sensors are incorporated in a dynamic network that is interconnected by both hormones and the nervous system. Regarding glucose...... is influenced by insulin. Another facet is that the control system has to cope with the complex traffic of metabolites inside cells and between organs on time-scales from minutes to months or more. The analysis is evaluated using setups called "virtual experiments", i.e. biosimulation models describing common...

  11. On polarimetric radar signatures of deep convection for model evaluation: columns of specific differential phase observed during MC3E

    Energy Technology Data Exchange (ETDEWEB)

    van Lier-Walqui, Marcus; Fridlind, Ann; Ackerman, Andrew S; Collis, Scott; Helmus, Jonathan; MacGorman, Donald R; North, Kirk; Kollias, Pavlos; Posselt, Derek J

    2016-02-01

    The representation of deep convection in general circulation models is in part informed by cloud-resolving models (CRMs) that function at higher spatial and temporal resolution; however, recent studies have shown that CRMs often fail at capturing the details of deep convection updrafts. With the goal of providing constraint on CRM simulation of deep convection updrafts, ground-based remote sensing observations are analyzed and statistically correlated for four deep convection events observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). Since positive values of specific differential phase observed above the melting level are associated with deep convection updraft cells, so-called columns are analyzed using two scanning polarimetric radars in Oklahoma: the National Weather Service Vance WSR-88D (KVNX) and the Department of Energy C-band Scanning Atmospheric Radiation Measurement (ARM) Precipitation Radar (C-SAPR). KVNX and C-SAPR volumes and columns are then statistically correlated with vertical winds retrieved via multi-Doppler wind analysis, lightning flash activity derived from the Oklahoma Lightning Mapping Array, and KVNX differential reflectivity . Results indicate strong correlations of volume above the melting level with updraft mass flux, lightning flash activity, and intense rainfall. Analysis of columns reveals signatures of changing updraft properties from one storm event to another as well as during event evolution. Comparison of to shows commonalities in information content of each, as well as potential problems with associated with observational artifacts.

  12. Polarimetric borehole radar measurement near Nojima fault and its application to subsurface crack characterization; Polarimetric borehole radar ni yoru Nojima danso shuhen no chika kiretsu keisoku jikken

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Taniguchi, Y.; Miwa, T.; Niitsuma, H. [Tohoku University, Sendai (Japan); Ikeda, R. [National Research Institute for Disaster Prevention, Tsukuba (Japan); Makino, K. [Geophysical Surveying and Consulting Co. Ltd., Tokyo (Japan)

    1997-05-27

    Practical application of subsurface crack characterization by the borehole radar measurement to which the radar polarimetric method was introduced was attempted to measuring objects for which the borehole radar has not been much used, for example, the inside of low loss rock mass or fracture zone where cracks tightly exist. A system was trially manufactured which makes the radar polarimetric measurement possible in the borehole at a 1000m depth and with a about 10cm diameter, and a field experiment was conducted for realizing the subsurface crack characterization near the Nojima fault. For the measuring experiment by the polarimetric borehole radar, used were Iwaya borehole and Hirabayashi borehole drilled in the north of Awaji-shima, Hyogo-ken. In a comparison of both polarization systems of Hirabayashi borehole, reflected waves at depths of 1038m and 1047m are relatively stronger in both polarization systems than those with the same polarization form and at different depths, whereas reflected waves around a 1017m depth are strong only as to the parallel polarization system. Characteristics of the polarization in this experiment indirectly reflect crack structures. 6 refs., 6 figs., 1 tab.

  13. Discrimination of Oil Slicks and Lookalikes in Polarimetric SAR Images Using CNN.

    Science.gov (United States)

    Guo, Hao; Wu, Danni; An, Jubai

    2017-08-09

    Oil slicks and lookalikes (e.g., plant oil and oil emulsion) all appear as dark areas in polarimetric Synthetic Aperture Radar (SAR) images and are highly heterogeneous, so it is very difficult to use a single feature that can allow classification of dark objects in polarimetric SAR images as oil slicks or lookalikes. We established multi-feature fusion to support the discrimination of oil slicks and lookalikes. In the paper, simple discrimination analysis is used to rationalize a preferred features subset. The features analyzed include entropy, alpha, and Single-bounce Eigenvalue Relative Difference (SERD) in the C-band polarimetric mode. We also propose a novel SAR image discrimination method for oil slicks and lookalikes based on Convolutional Neural Network (CNN). The regions of interest are selected as the training and testing samples for CNN on the three kinds of polarimetric feature images. The proposed method is applied to a training data set of 5400 samples, including 1800 crude oil, 1800 plant oil, and 1800 oil emulsion samples. In the end, the effectiveness of the method is demonstrated through the analysis of some experimental results. The classification accuracy obtained using 900 samples of test data is 91.33%. It is here observed that the proposed method not only can accurately identify the dark spots on SAR images but also verify the ability of the proposed algorithm to classify unstructured features.

  14. Wind direction over the ocean determined by an airborne, imaging, polarimetric radiometer system

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    2001-01-01

    The speed and direction of winds over the ocean can be determined by polarimetric radiometers. This has been established by theoretical work and demonstrated experimentally using airborne radiometers carrying out circle flights and thus measuring the full 360° azimuthal response from the sea surf...

  15. Polarimetric Determination of Starch in Raw Materials and Discharged Waste from Beer Production

    Directory of Open Access Journals (Sweden)

    Anca Farcas

    2013-11-01

    Full Text Available Brewer’s spent grain (BGS is a by-product of thebrewing process, consisting of the solid fraction of barley malt remainingafter separation of worth. In this research, raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method.

  16. The Solar Orbiter Mission and its Polarimetric and Helioseismic Imager (SO/PHI)

    Energy Technology Data Exchange (ETDEWEB)

    Gandorfer, Achim; Solanki, Sami K; Woch, Joachim [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany); Pillet, Valentin MartInez [Instituto de Astrofisica de Canarias, C/ VIa Lactea, s/n, E38205 - La Laguna (Tenerife) (Spain); Herrero, Alberto Alvarez [Instituto Nacional de Tecnica Aeroespacial, E-28850, Torrejon de Ardoz, Madrid (Spain); Appourchaux, Thierry, E-mail: gandorfer@mps.mpg.de [Institut d' Astrophysique Spatiale, CNRS-Universite Paris XI UMR8617, 91405 Orsay Cedex (France)

    2011-01-01

    We briefly outline the scientific and instrumental aspects of ESA's Solar Orbiter mission. Special emphasis is given to the Polarimetric and Helioseismic Imager, the instrument with the highest relevance for helioseismology applications, which will observe gas motions and the vector magnetic field in the photosphere at high spatial and temporal resolution.

  17. Applications of Polarimetric Radar to the Hydrometeorology of Urban Floods in St. Louis

    Science.gov (United States)

    Chaney, M. M.; Smith, J. A.; Baeck, M. L.

    2017-12-01

    Predicting and responding to flash flooding requires accurate spatial and temporal representation of rainfall rates. The polarimetric upgrade of all US radars has led to optimism about more accurate rainfall rate estimation from the NEXRAD network of WSR-88D radars in the US. Previous work has proposed different algorithms to do so, but significant uncertainties remain, especially for extreme short-term rainfall rates that control flash floods in urban settings. We will examine the relationship between radar rainfall estimates and gage rainfall rates for a catalog of 30 storms in St. Louis during the period of polarimetric radar measurements, 2012-2016. The storms are selected to provide a large sample of extreme rainfall measurements at the 15-minute to 3-hour time scale. A network of 100 rain gages and a lack of orographic or coastal effects make St. Louis an interesting location to study these relationships. A better understanding of the relationships between polarimetric radar measurements and gage rainfall rates will aid in refining polarimetric radar rainfall algorithms, in turn helping hydrometeorologists predict flash floods and other hazards associated with severe rainfall. Given the fact that St. Louis contains some of the flashiest watersheds in the United States (Smith and Smith, 2015), it is an especially important urban area in which to have accurate, real-time rainfall data. Smith, Brianne K, and James A Smith. "The Flashiest Watersheds in the Contiguous United States." American Meteorological Society (2015): 2365-2381. Web.

  18. Maritime target and sea clutter measurements with a coherent Doppler polarimetric surveillance radar

    NARCIS (Netherlands)

    Smith, A.J.E.; Gelsema, S.J.; Kester, L.J.H.M.; Melief, H.W.; Premel Cabic, G.; Theil, A.; Woudenberg, E.

    2002-01-01

    Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary

  19. Forest mapping using bi-aspect polarimetric SAR data in southwest China

    Science.gov (United States)

    Zhang, Fengli; Xu, Maosong; Xia, Zhongsheng; Wan, Zi; Li, Kun; Li, Xiaofang

    2009-10-01

    Synthetic aperture radar (SAR) provides a powerful tool for forestry inventory because of its all-weather and all-day capabilities. In this paper forest mapping method using bi-aspect polarimetric SAR data acquired from ascending and descending path has been studied. Zhazuo forest farm in Guizhou province was selected as test site and an 8-temporal field experiment was designed to obtain bio-physical parameters and spatial structure parameters of the 12 sample plots. Then the Michigan Microwave Canopy Scattering model (MIMICS) was employed to analyze the seasonal variation of these 4 types of managed forests. Using polarimetric Radarsat 2 data, scattering mechanisms of each forest type were determined and polarimetric variables were extracted and analyzed for forest discrimination. Considering the inherent geometric distortion of SAR imaging in hilly areas, a geometric correction strategy using bi-aspect SAR images and high resolution DEM was proposed. Then support vector machines method was adopted for classification of the whole test area. Experiments show that the bi-aspect geometric strategy is useful for hilly areas especially for shadow elimination in SAR image, and polarimetric SAR data is helpful to forest mapping.

  20. Compact Polarimetric SAR Ship Detection with m-δ Decomposition Using Visual Attention Model

    Directory of Open Access Journals (Sweden)

    Lu Xu

    2016-09-01

    Full Text Available A few previous studies have illustrated the potentials of compact polarimetric Synthetic Aperture Radar (CP SAR in ship detection. In this paper, we design a ship detection algorithm of CP SAR from the perspective of computer vision. A ship detection algorithm using the pulsed cosine transform (PCT visual attention model is proposed to suppress background clutter and highlight conspicuous ship targets. It is the first time that a visual attention model is introduced to CP SAR application. The proposed algorithm is a quick and complete framework for practical use. Polarimetric features—the relative phase δ and volume scattering component—are extracted from m-δ decomposition to eliminate false alarms and modify the PCT model. The constant false alarm rate (CFAR algorithm based on lognormal distribution is adopted to detect ship targets, after a clutter distribution fitting procedure of the modified saliency map. The proposed method is then tested on three simulated circular-transmit-linear-receive (CTLR mode images, which covering East Sea of China. Compared with the detection results of SPAN and the saliency map with only single-channel amplitude, the proposed method achieves the highest detection rates and the lowest misidentification rate and highest figure of merit, proving the effectiveness of polarimetric information of compact polarimetric SAR ship detection and the enhancement from the visual attention model.

  1. Feature level fusion of polarimetric infrared and GPR data for landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Jong, W. de; Schutte, K.; Yarovoy, A.G.; Kovalenko, V.; Bloemenkamp, R.F.

    2003-01-01

    Feature-level sensor fusion is the process where specific information (i.e. features) from objects detected by different sensors are combined and classified. This paper focuses on the feature-level fusion procedure for a sensor combination consisting of a polarimetric infrared (IR) imaging sensor

  2. Design of a Small, Low Cost, P-Band Airborne Polarimetric Synthetic Aperture Radar

    NARCIS (Netherlands)

    Figueras i Ventura, J.; Hoogeboom, P.

    2004-01-01

    A preliminary study of the design of a small, low cost, P-band airborne, polarimetric Synthetic Aperture Radar desired by the Wageningen University and the Borneo Orangutan Survival Foundation (BOS) to carry out forest biomass monitoring in Indonesia is presented. The requirements of the application

  3. Unsupervised polarimetric synthetic aperture radar image classification based on sketch map and adaptive Markov random field

    Science.gov (United States)

    Shi, Junfei; Li, Lingling; Liu, Fang; Jiao, Licheng; Liu, Hongying; Yang, Shuyuan; Liu, Lu; Hao, Hongxia

    2016-04-01

    Markov random field (MRF) model is an effective tool for polarimetric synthetic aperture radar (PolSAR) image classification. However, due to the lack of suitable contextual information in conventional MRF methods, there is usually a contradiction between edge preservation and region homogeneity in the classification result. To preserve edge details and obtain homogeneous regions simultaneously, an adaptive MRF framework is proposed based on a polarimetric sketch map. The polarimetric sketch map can provide the edge positions and edge directions in detail, which can guide the selection of neighborhood structures. Specifically, the polarimetric sketch map is extracted to partition a PolSAR image into structural and nonstructural parts, and then adaptive neighborhoods are learned for two parts. For structural areas, geometric weighted neighborhood structures are constructed to preserve image details. For nonstructural areas, the maximum homogeneous regions are obtained to improve the region homogeneity. Experiments are taken on both the simulated and real PolSAR data, and the experimental results illustrate that the proposed method can obtain better performance on both region homogeneity and edge preservation than the state-of-the-art methods.

  4. Polarimetric SAR Target Scattering Interpretation in Rotation Domain: Theory and Application

    Directory of Open Access Journals (Sweden)

    Chen Siwei

    2017-10-01

    Full Text Available Backscattering of radar targets is sensitive to the relative geometry between target orientations and the radar line of sight. This scattering diversity makes imaging radar represented by polarimetric Synthetic Aperture Radar (SAR information processing and applications very difficult. This situation has become one of the main bottlenecks in the interpretation of the target scattering mechanism and quantitative applications. In this work, we review and introduce a new interpretation of the target scattering mechanism in the rotation domain along the radar line of sight. This concept includes the recently established uniform polarimetric matrix rotation theory and polarimetric coherence pattern visualization and interpretation in the rotation domain. The core idea of target scattering interpretation in the rotation domain is to extend the amount of target information acquired at a given geometry to the rotation domain, which then provides fundamentals for the deep mining and utilization of target scattering information. This work mainly focuses on the investigation of derived new polarimetric feature sets and application demonstrations. Comparison study results validate the promising potential for the application of the established interpretation framework in the rotation domain with respect to target discrimination and classification.

  5. Polarimetric Determination of Starch in Raw Materials and Discharged Waste from Beer Production

    OpenAIRE

    Anca Farcas; Maria Tofana; Sonia Socaci; Stancuta Scrob; Liana Salanta; Doinita Bors

    2013-01-01

    Brewer’s spent grain (BGS) is a by-product of thebrewing process, consisting of the solid fraction of barley malt remainingafter separation of worth. In this research, raw materials and discharged waste from beer production were evaluated on the basis of starch content, using Ewers polarimetric method.

  6. Comparisons of Circular Transmit and Linear Receive Compact Polarimetric SAR Features for Oil Slicks Discrimination

    Directory of Open Access Journals (Sweden)

    Yu Li

    2015-01-01

    Full Text Available Compact polarimetric (CP synthetic aperture radar (SAR has proven its potential in distinguishing oil slicks and look-alikes. Polarimetric information can be retrieved directly from scattering vector or from reconstructed pseudo-Quad-Pol covariance matrix of CP SAR data. In this paper, we analysed features from Circular Transmit and Linear Receive (CTLR CP SAR data that are derived by taking both of these two methods. K-means clustering followed by accuracy assessment was also implemented for performance evaluation. Through experiments that were conducted based on L-band UAVSAR fully polarimetric data, it was found that optimum extraction methods varied for different features. The histogram analysis and segmentation results also demonstrated the comparable performance of CP SAR features in distinguishing different damping properties within oil slicks. This study proposed a framework of statistically analyzing polarimetric SAR (Pol-SAR features and provided guidelines for determining optimum feature extraction methods from CP SAR data and for marine oil-spills detection and classification.

  7. Probe-Fed Stacked Microstrip Patch Antenna for High-Resolution Polarimetric C-Band SAR

    DEFF Research Database (Denmark)

    Granholm, Johan; Skou, Niels

    2000-01-01

    The paper describes a C-band, dual-linear polarization wideband antenna for use in the next-generation of the Danish high-resolution, airborne polarimetric synthetic aperture radar (SAR) system, EMISAR. The design and performance of a probe-fed, stacked microstrip patch element, operating from 4...

  8. The PHARUS Project; Real Time Digital Processing of Airborne Polarimetric Radar Signals

    NARCIS (Netherlands)

    Pouwels, H.; Hoogeboom, P.; Koomen, P.J.; Snoeij, P.

    1992-01-01

    The Dutch PHARUS project aims for the developrlenÈ of a polarimetric C-band aircraft SAR, to be finalized in 1994. The PHARUS systen consists of three subsystens: the radar, the subsystem for the onboard data processing and recording and the ground-based subsystem for SAR processing. PHARUS is a

  9. The Design and Development of a Polarimetric Phased Array Airborne SAR Sensor

    NARCIS (Netherlands)

    Snoeij, P.; Pouwels, H.; Koomen, P.J.; Vermeulen, B.C.B.; Hoogeboom, P.

    1996-01-01

    A polarimetric C-band airborne SAR has been developed in the Netherlands. The system makes use of a phased array antenna with solid state amplifiers. The project consists of two phases, a definition phase and a realization phase. The definition phase consisted of the actual realization of a SAR

  10. Glucose and cardiovascular risk

    NARCIS (Netherlands)

    Fuchs, M.; Hoekstra, J. B. L.; Mudde, A. H.

    2002-01-01

    The American Diabetes Association and the World Health Organisation have recently redefined the spectrum of abnormal glucose tolerance. The criteria for diabetes mellitus were sharpened and impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were classified as intermediate stages

  11. Levee Seepage Detection in the Sacramento-San Joaquin Delta Using Polarimetric SAR

    Science.gov (United States)

    An, K.; Jones, C. E.; Bekaert, D. P.

    2017-12-01

    The Sacramento-San Joaquin Delta's extensive levee system protects over 2,800 km2 of reclaimed lands and serves as the main irrigation and domestic water supply for the state of California. However, ongoing subsidence and disaster threats from floods and earthquakes make the Delta levee system highly vulnerable, endangering water supplies for 23 million California residents and 2.5 million acres of agricultural land. Levee failure in the Delta can cause saltwater intrusion from San Francisco Bay, reducing water quality and curtailing water exports to residents, commercial users, and farmers. To protect the Delta levee system, it is essential to search for signs of seepage in which water is piping through or beneath levees, which can be associated with deformation of the levees themselves. Until now, in-situ monitoring has largely been applied, however, this is a time-consuming and expensive approach. We use data acquired with NASA's UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar) airborne radar instrument to identify and characterize levee seepages and associated land subsidence through advanced remote sensing technologies. The high spatial resolution of UAVSAR can help to direct surveys to areas that are likely to be experiencing damage. UAVSAR is an L-band airborne sensor with high signal-to-noise ratio, repeat flight track accuracy, and spatial resolution of 7x7 m2 (for multi-looked products) that is necessary for detailed levee monitoring. The adaptability of radar instruments in their ability to see through smoke, haze, and clouds during the day or night, is especially relevant during disaster events, when cloud cover or lack of solar illumination inhibits traditional visual surveys of damage. We demonstrate the advantages of combining polarimetric radar imagery with geographic information systems (GIS) datasets in locating seepage features along critical levee infrastructure in the Delta for 2009-2016. The ability to efficiently locate potential

  12. Investigation of Polarimetric and Electrical Characteristics of Natural and Triggered Lightning Strikes

    Science.gov (United States)

    Hyland, P. T.; Biggerstaff, M. I.; Uman, M. A.; Jordan, D. M.; Hill, J. D.; Pilkey, J. T.; Ngin, T.; Blakeslee, R. J.; Krehbiel, P. R.; Rison, W.; Winn, W. P.; Eack, K.; Trueblood, J.; Edens, H. E.

    2013-12-01

    For the past three summers, the University of Oklahoma has deployed three mobile, polarimetric radars to the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida and Langmuir Laboratory near Socorro, New Mexico for the purpose of investigating the relationship between cloud structure and the propagation of triggered and natural lightning channels. This presentation will highlight observations from select natural and triggered events at these two facilities. During the summer of 2012, University of Oklahoma radar operators made a launch recommendation to the ICLRT during the passage of Tropical Storm Debby over northeast Florida that resulted in a successful triggered flash with 11 return strokes. The trigger was attempted as precipitation streamers within the stratiform rainbands of Tropical Storm Debby approached the launch site. According to the National Lightning Detection Network (NLDN), there were no reported natural cloud-to-ground (CG) flashes within 60 km of the ICLRT 20 hours before and eight hours after the triggered flash. The recommendation was made based on previous analyses of the storm structure of trigger attempts from the ICLRT that indicated the coincidence of several successful triggers with descending regions of enhanced radar reflectivity, or descending precipitation packets (DePPs). Polarimetric data from the frequency-agile Rapid-scanning X-band Polarimetric (RaXPol) radar as well as data from the lightning mapping array (LMA) and electric field meter (EFM) networks from the ICLRT for this event will be presented. Past analyses also revealed ice alignment signatures in differential phase and specific differential phase as strong electric fields near the top of electrified clouds cause small ice particles to become vertically aligned. These signatures are especially noticeable for circularly polarized radars. Polarimetric data from the Shared Mobile Atmospheric Research & Teaching (SMART) radar and Ra

  13. Airborne polarimetric Doppler weather radar: trade-offs between various engineering specifications

    Science.gov (United States)

    Vivekanandan, Jothiram; Loew, Eric

    2018-01-01

    NCAR EOL is investigating potential configurations for the next-generation airborne phased array radar (APAR) that is capable of retrieving dynamic and microphysical characteristics of clouds and precipitation. The APAR will operate at C band. The APAR will use the electronic scanning (e-scan) feature to acquire the optimal number of independent samples for recording research-quality measurements. Since the airborne radar has only a limited time for collecting measurements over a specified region (moving aircraft platform ˜ 100 m s-1), beam multiplexing will significantly enhance its ability to collect high-resolution, research-quality measurements. Beam multiplexing reduces errors in radar measurements while providing rapid updates of scan volumes. Beamwidth depends on the size of the antenna aperture. Beamwidth and directivity of elliptical, circular, and rectangular antenna apertures are compared and radar sensitivity is evaluated for various polarimetric configurations and transmit-receive (T/R) elements. In the case of polarimetric measurements, alternate transmit with alternate receive (single-channel receiver) and simultaneous reception (dual-channel receiver) is compared. From an overall architecture perspective, element-level digitization of T/R module versus digital sub-array is considered with regard to flexibility in adaptive beamforming, polarimetric performance, calibration, and data quality. Methodologies for calibration of the radar and removing bias in polarimetric measurements are outlined. The above-mentioned engineering options are evaluated for realizing an optimal APAR system suitable for measuring the high temporal and spatial resolutions of Doppler and polarimetric measurements of precipitation and clouds.

  14. Polarimetric survey of main-belt asteroids⋆. III. Results for 33 X-type objects

    Science.gov (United States)

    Cañada-Assandri, M.; Gil-Hutton, R.; Benavidez, P.

    2012-06-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15 m telescope. The Torino polarimeter is an instrument that allows the simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data of a sample of more than 170 asteroids were obtained. In this paper the results for 33 X-type objects are presented, several of them are being polarimetrically observed for the first time. Using these data we found polarization curves and polarimetric parameters for different groups among this taxonomic class and that there are objects with very different albedo in the sub-classes of the X taxonomic complex. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Table 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/542/A11

  15. A self-powered glucose biosensing system.

    Science.gov (United States)

    Slaughter, Gymama; Kulkarni, Tanmay

    2016-04-15

    A self-powered glucose biosensor (SPGS) system is fabricated and in vitro characterization of the power generation and charging frequency characteristics in glucose analyte are described. The bioelectrodes consist of compressed network of three-dimensional multi-walled carbon nanotubes with redox enzymes, pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and laccase functioning as the anodic and cathodic catalyst, respectively. When operated in 45 mM glucose, the biofuel cell exhibited an open circuit voltage and power density of 681.8 mV and 67.86 µW/cm(2) at 335 mV, respectively, with a current density of 202.2 µA/cm(2). Moreover, at physiological glucose concentration (5mM), the biofuel cell exhibits open circuit voltage and power density of 302.1 mV and 15.98 µW/cm(2) at 166.3 mV, respectively, with a current density of 100 µA/cm(2). The biofuel cell assembly produced a linear dynamic range of 0.5-45 mM glucose. These findings show that glucose biofuel cells can be further investigated in the development of a self-powered glucose biosensor by using a capacitor as the transducer element. By monitoring the capacitor charging frequencies, which are influenced by the concentration of the glucose analyte, a linear dynamic range of 0.5-35 mM glucose is observed. The operational stability of SPGS is monitored over a period of 63 days and is found to be stable with 15.38% and 11.76% drop in power density under continuous discharge in 10mM and 20mM glucose, respectively. These results demonstrate that SPGSs can simultaneously generate bioelectricity to power ultra-low powered devices and sense glucose. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Theory and approach of information retrievals from electromagnetic scattering and remote sensing

    CERN Document Server

    Jin, Ya-Qiu

    2006-01-01

    Covers several hot topics in current research of electromagnetic scattering, and radiative transfer in complex and random media, polarimetric scattering and SAR imagery technology, data validation and information retrieval from space-borne remote sensing, computational electromagnetics, etc.Including both forward modelling and inverse problems, analytic theory and numerical approachesAn overall summary of the author's works during most recent yearsAlso presents some insight for future research topics.

  17. Classification of Polarimetric SAR Image Based on Support Vector Machine Using Multiple-Component Scattering Model and Texture Features

    Directory of Open Access Journals (Sweden)

    Lamei Zhang

    2010-01-01

    Full Text Available The classification of polarimetric SAR image based on Multiple-Component Scattering Model (MCSM and Support Vector Machine (SVM is presented in this paper. MCSM is a potential decomposition method for a general condition. SVM is a popular tool for machine learning tasks involving classification, recognition, or detection. The scattering powers of single-bounce, double-bounce, volume, helix, and wire scattering components are extracted from fully polarimetric SAR images. Combining with the scattering powers of MCSM and the selected texture features from Gray-level cooccurrence matrix (GCM, SVM is used for the classification of polarimetric SAR image. We generate a validity test for the proposed method using Danish EMISAR L-band fully polarimetric data of Foulum Area (DK, Denmark. The preliminary result indicates that this method can classify most of the areas correctly.

  18. GPM GROUND VALIDATION NASA S-BAND DUAL POLARIMETRIC (NPOL) DOPPLER RADAR MC3E V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GPM Ground Validation NASA S-band Dual Polarimetric (NPOL) Doppler Radar MC3E dataset was collected by the NASA NPOL radar, which was developed by a research...

  19. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walt; Krajewski, Witek; Wolff, David; Gatlin, Patrick

    2015-04-01

    The Global Precipitation Measurement (GPM) Mission Iowa Flood Studies (IFloodS) campaign was conducted in central and northeastern Iowa during the months of April-June, 2013. Specific science objectives for IFloodS included quantification of uncertainties in satellite and ground-based estimates of precipitation, 4-D characterization of precipitation physical processes and associated parameters (e.g., size distributions, water contents, types, structure etc.), assessment of the impact of precipitation estimation uncertainty and physical processes on hydrologic predictive skill, and refinement of field observations and data analysis approaches as they pertain to future GPM integrated hydrologic validation and related field studies. In addition to field campaign archival of raw and processed satellite data (including precipitation products), key ground-based platforms such as the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms, and a large network of 2D Video and Parsivel disdrometers were deployed. In something of a canonical approach, the radar (NPOL in particular), gauge and disdrometer observational assets were deployed to create a consistent high-quality distributed (time and space sampling) radar-based ground "reference" rainfall dataset, with known uncertainties, that could be used for assessing the satellite-based precipitation products at a range of space/time scales. Subsequently, the impact of uncertainties in the satellite products could be evaluated relative to the ground-benchmark in coupled weather, land-surface and distributed hydrologic modeling frameworks as related to flood prediction. Relative to establishing the ground-based "benchmark", numerous avenues were pursued in the making and verification of IFloodS "reference" dual-polarimetric radar-based rain maps, and this study documents the process and results as they pertain specifically

  20. Construction of Polarimetric Radar-Based Reference Rain Maps for the Iowa Flood Studies Campaign

    Science.gov (United States)

    Petersen, Walter; Wolff, David; Krajewski, Witek; Gatlin, Patrick

    2015-01-01

    The Global Precipitation Measurement (GPM) Mission Iowa Flood Studies (IFloodS) campaign was conducted in central and northeastern Iowa during the months of April-June, 2013. Specific science objectives for IFloodS included quantification of uncertainties in satellite and ground-based estimates of precipitation, 4-D characterization of precipitation physical processes and associated parameters (e.g., size distributions, water contents, types, structure etc.), assessment of the impact of precipitation estimation uncertainty and physical processes on hydrologic predictive skill, and refinement of field observations and data analysis approaches as they pertain to future GPM integrated hydrologic validation and related field studies. In addition to field campaign archival of raw and processed satellite data (including precipitation products), key ground-based platforms such as the NASA NPOL S-band and D3R Ka/Ku-band dual-polarimetric radars, University of Iowa X-band dual-polarimetric radars, a large network of paired rain gauge platforms, and a large network of 2D Video and Parsivel disdrometers were deployed. In something of a canonical approach, the radar (NPOL in particular), gauge and disdrometer observational assets were deployed to create a consistent high-quality distributed (time and space sampling) radar-based ground "reference" rainfall dataset, with known uncertainties, that could be used for assessing the satellite-based precipitation products at a range of space/time scales. Subsequently, the impact of uncertainties in the satellite products could be evaluated relative to the ground-benchmark in coupled weather, land-surface and distributed hydrologic modeling frameworks as related to flood prediction. Relative to establishing the ground-based "benchmark", numerous avenues were pursued in the making and verification of IFloodS "reference" dual-polarimetric radar-based rain maps, and this study documents the process and results as they pertain specifically

  1. Hypothalamic leucine metabolism regulates liver glucose production.

    Science.gov (United States)

    Su, Ya; Lam, Tony K T; He, Wu; Pocai, Alessandro; Bryan, Joseph; Aguilar-Bryan, Lydia; Gutiérrez-Juárez, Roger

    2012-01-01

    Amino acids profoundly affect insulin action and glucose metabolism in mammals. Here, we investigated the role of the mediobasal hypothalamus (MBH), a key center involved in nutrient-dependent metabolic regulation. Specifically, we tested the novel hypothesis that the metabolism of leucine within the MBH couples the central sensing of leucine with the control of glucose production by the liver. We performed either central (MBH) or systemic infusions of leucine in Sprague-Dawley male rats during basal pancreatic insulin clamps in combination with various pharmacological and molecular interventions designed to modulate leucine metabolism in the MBH. We also examined the role of hypothalamic ATP-sensitive K(+) channels (K(ATP) channels) in the effects of leucine. Enhancing the metabolism of leucine acutely in the MBH lowered blood glucose through a biochemical network that was insensitive to rapamycin but strictly dependent on the hypothalamic metabolism of leucine to α-ketoisocaproic acid and, further, insensitive to acetyl- and malonyl-CoA. Functional K(ATP) channels were also required. Importantly, molecular attenuation of this central sensing mechanism in rats conferred susceptibility to developing hyperglycemia. We postulate that the metabolic sensing of leucine in the MBH is a previously unrecognized mechanism for the regulation of hepatic glucose production required to maintain glucose homeostasis.

  2. CSF glucose test

    Science.gov (United States)

    Glucose test - CSF; Cerebrospinal fluid glucose test ... The glucose level in the CSF should be 50 to 80 mg/100 mL (or greater than 2/3 ... Abnormal results include higher and lower glucose levels. Abnormal ... or fungus) Inflammation of the central nervous system Tumor

  3. Polarimetric synthetic aperture radar application for tropical peatlands classification: a case study in Siak River Transect, Riau Province, Indonesia

    Science.gov (United States)

    Novresiandi, Dandy Aditya; Nagasawa, Ryota

    2017-01-01

    Mapping spatial distributions of tropical peatlands is important for properly estimating carbon emissions and for providing information that aids in the sustainable management of tropical peatlands, particularly in Indonesia. This study evaluated the performance of phased array type L-band synthetic aperture radar (SAR) (PALSAR) dual-polarization and fully polarimetric data for tropical peatlands classification. The study area was in Siak River Transect, Riau Province, Indonesia, a rapidly developing region, where the peatland has been intensively converted mostly into oil palm plantations over the last two decades. Thus, polarimetric features derived after polarimetric decompositions, backscatter coefficients measurements, and the radar vegetation index were evaluated to classify tropical peatlands using the decision tree classifier. Overall, polarimetric features generated by the combination of dual-polarization and fully polarimetric data yielded an overall accuracy (OA) of 69% and a kappa coefficient (K) of 0.57. The integration of an additional feature, "distance to river," to the algorithm increased the OA to 76% and K to 0.66. These results indicated that the methodology in this study might serve as an efficient tool in tropical peatlands classification, especially when involving the use of L-band SAR dual-polarization and fully polarimetric data.

  4. Polarimetric Radar Characteristics of Simulated and Observed Intense Convection Between Continental and Maritime Environment

    Science.gov (United States)

    Matsui, T.; Dolan, B.; Tao, W. K.; Rutledge, S. A.; Iguchi, T.; Barnum, J. I.; Lang, S. E.

    2017-12-01

    This study presents polarimetric radar characteristics of intense convective cores derived from observations as well as a polarimetric-radar simulator from cloud resolving model (CRM) simulations from Midlatitude Continental Convective Clouds Experiment (MC3E) May 23 case over Oklahoma and a Tropical Warm Pool-International Cloud Experiment (TWP-ICE) Jan 23 case over Darwin, Australia to highlight the contrast between continental and maritime convection. The POLArimetric Radar Retrieval and Instrument Simulator (POLARRIS) is a state-of-art T-matrix-Mueller-Matrix-based polarimetric radar simulator that can generate synthetic polarimetric radar signals (reflectivity, differential reflectivity, specific differential phase, co-polar correlation) as well as synthetic radar retrievals (precipitation, hydrometeor type, updraft velocity) through the consistent treatment of cloud microphysics and dynamics from CRMs. The Weather Research and Forecasting (WRF) model is configured to simulate continental and maritime severe storms over the MC3E and TWP-ICE domains with the Goddard bulk 4ICE single-moment microphysics and HUCM spectra-bin microphysics. Various statistical diagrams of polarimetric radar signals, hydrometeor types, updraft velocity, and precipitation intensity are investigated for convective and stratiform precipitation regimes and directly compared between MC3E and TWP-ICE cases. The result shows MC3E convection is characterized with very strong reflectivity (up to 60dBZ), slight negative differential reflectivity (-0.8 0 dB) and near-zero specific differential phase above the freezing levels. On the other hand, TWP-ICE convection shows strong reflectivity (up to 50dBZ), slight positive differential reflectivity (0 1.0 dB) and differential phase (0 0.8 dB/km). Hydrometeor IDentification (HID) algorithm from the observation and simulations detect hail-dominant convection core in MC3E, while graupel-dominant convection core in TWP-ICE. This land-ocean contrast

  5. Accuracy of flash glucose monitoring and continuous glucose monitoring technologies: Implications for clinical practice.

    Science.gov (United States)

    Ajjan, Ramzi A; Cummings, Michael H; Jennings, Peter; Leelarathna, Lalantha; Rayman, Gerry; Wilmot, Emma G

    2018-02-01

    Continuous glucose monitoring and flash glucose monitoring technologies measure glucose in the interstitial fluid and are increasingly used in diabetes care. Their accuracy, key to effective glycaemic management, is usually measured using the mean absolute relative difference of the interstitial fluid sensor compared to reference blood glucose readings. However, mean absolute relative difference is not standardised and has limitations. This review aims to provide a consensus opinion on assessing accuracy of interstitial fluid glucose sensing technologies. Mean absolute relative difference is influenced by glucose distribution and rate of change; hence, we express caution on the reliability of comparing mean absolute relative difference data from different study systems and conditions. We also review the pitfalls associated with mean absolute relative difference at different glucose levels and explore additional ways of assessing accuracy of interstitial fluid devices. Importantly, much data indicate that current practice of assessing accuracy of different systems based on individualised mean absolute relative difference results has limitations, which have potential clinical implications. Healthcare professionals must understand the factors that influence mean absolute relative difference as a metric for accuracy and look at additional assessments, such as consensus error grid analysis, when evaluating continuous glucose monitoring and flash glucose monitoring systems in diabetes care. This in turn will ensure that management decisions based on interstitial fluid sensor data are both effective and safe.

  6. Investigation of the Capability of Compact Polarimetric SAR Interferometry to Estimate Forest Height

    Science.gov (United States)

    Zhang, Hong; Xie, Lei; Wang, Chao; Chen, Jiehong

    2013-08-01

    The main objective of this paper is to investigate the capability of compact Polarimetric SAR Interferometry (C-PolInSAR) on forest height estimation. For this, the pseudo fully polarimetric interferomteric (F-PolInSAR) covariance matrix is firstly reconstructed, then the three- stage inversion algorithm, hybrid algorithm, Music and Capon algorithm are applied to both C-PolInSAR covariance matrix and pseudo F-PolInSAR covariance matrix. The availability of forest height estimation is demonstrated using L-band data generated by simulator PolSARProSim and X-band airborne data acquired by East China Research Institute of Electronic Engineering, China Electronics Technology Group Corporation.

  7. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    Directory of Open Access Journals (Sweden)

    T. H. Raupach

    2017-07-01

    Full Text Available A new technique for estimating the raindrop size distribution (DSD from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed using a double-moment normalisation. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observations. In the three tested domains, in terms of DSD moments, rain rate, and characteristic drop diameter, the proposed method performs similarly to and often better than a state-of-the-art DSD-retrieval technique. The approach is flexible because no specific DSD model is prescribed. In addition, a method is proposed to treat noisy radar data to improve DSD-retrieval performance with radar measurements.

  8. Retrieval of the raindrop size distribution from polarimetric radar data using double-moment normalisation

    Science.gov (United States)

    Raupach, Timothy H.; Berne, Alexis

    2017-07-01

    A new technique for estimating the raindrop size distribution (DSD) from polarimetric radar data is proposed. Two statistical moments of the DSD are estimated from polarimetric variables, and the DSD is reconstructed using a double-moment normalisation. The technique takes advantage of the relative invariance of the double-moment normalised DSD. The method was tested using X-band radar data and networks of disdrometers in three different climatic regions. Radar-derived estimates of the DSD compare reasonably well to observations. In the three tested domains, in terms of DSD moments, rain rate, and characteristic drop diameter, the proposed method performs similarly to and often better than a state-of-the-art DSD-retrieval technique. The approach is flexible because no specific DSD model is prescribed. In addition, a method is proposed to treat noisy radar data to improve DSD-retrieval performance with radar measurements.

  9. Photo-polarimetric sensitivities to layering and mixing of absorbing aerosols

    Directory of Open Access Journals (Sweden)

    O. V. Kalashnikova

    2011-09-01

    Full Text Available We investigate to what extent multi-angle polarimetric measurements are sensitive to vertical mixing/layering of absorbing aerosols, adopting calibration uncertainty of 1.5% in intensity and 0.5% in the degree of linear polarization of Multiangle Spectro-Polarimetric Imager (MSPI. Employing both deterministic and Monte Carlo radiative transfer codes with polarization, we conduct modeling experiments to determine how the measured Stokes vector elements are affected at UV and short visible wavelengths by the vertical distribution, mixing and layering of smoke and dust aerosols for variety of microphysical parameters. We find that multi-angular polarimetry holds the potential to infer dust-layer heights and thicknesses at blue visible channel due to its lesser sensitivity to changes in dust coarse mode optical properties, but higher sensitivity to the dust vertical profiles. Our studies quantify requirements for obtaining simultaneous information on aerosol layer height and absorption under MSPI measurement uncertainties.

  10. Recent Advances in the Cellular and Molecular Mechanisms of Hypothalamic Neuronal Glucose Detection.

    Science.gov (United States)

    Fioramonti, Xavier; Chrétien, Chloé; Leloup, Corinne; Pénicaud, Luc

    2017-01-01

    The hypothalamus have been recognized for decades as one of the major brain centers for the control of energy homeostasis. This area contains specialized neurons able to detect changes in nutrients level. Among them, glucose-sensing neurons use glucose as a signaling molecule in addition to its fueling role. In this review we will describe the different sub-populations of glucose-sensing neurons present in the hypothalamus and highlight their nature in terms of neurotransmitter/neuropeptide expression. This review will particularly discuss whether pro-opiomelanocortin (POMC) neurons from the arcuate nucleus are directly glucose-sensing. In addition, recent observations in glucose-sensing suggest a subtle system with different mechanisms involved in the detection of changes in glucose level and their involvement in specific physiological functions. Several data point out the critical role of reactive oxygen species (ROS) and mitochondria dynamics in the detection of increased glucose. This review will also highlight that ATP-dependent potassium (K ATP ) channels are not the only channels mediating glucose-sensing and discuss the new role of transient receptor potential canonical channels (TRPC). We will discuss the recent advances in the determination of glucose-sensing machinery and propose potential line of research needed to further understand the regulation of brain glucose detection.

  11. Investigation of hydrometeor classification uncertainties through the POLARRIS polarimetric radar simulator

    Science.gov (United States)

    Dolan, B.; Rutledge, S. A.; Barnum, J. I.; Matsui, T.; Tao, W. K.; Iguchi, T.

    2017-12-01

    POLarimetric Radar Retrieval and Instrument Simulator (POLARRIS) is a framework that has been developed to simulate radar observations from cloud resolving model (CRM) output and subject model data and observations to the same retrievals, analysis and visualization. This framework not only enables validation of bulk microphysical model simulated properties, but also offers an opportunity to study the uncertainties associated with retrievals such as hydrometeor classification (HID). For the CSU HID, membership beta functions (MBFs) are built using a set of simulations with realistic microphysical assumptions about axis ratio, density, canting angles, size distributions for each of ten hydrometeor species. These assumptions are tested using POLARRIS to understand their influence on the resulting simulated polarimetric data and final HID classification. Several of these parameters (density, size distributions) are set by the model microphysics, and therefore the specific assumptions of axis ratio and canting angle are carefully studied. Through these sensitivity studies, we hope to be able to provide uncertainties in retrieved polarimetric variables and HID as applied to CRM output. HID retrievals assign a classification to each point by determining the highest score, thereby identifying the dominant hydrometeor type within a volume. However, in nature, there is rarely just one a single hydrometeor type at a particular point. Models allow for mixing ratios of different hydrometeors within a grid point. We use the mixing ratios from CRM output in concert with the HID scores and classifications to understand how the HID algorithm can provide information about mixtures within a volume, as well as calculate a confidence in the classifications. We leverage the POLARRIS framework to additionally probe radar wavelength differences toward the possibility of a multi-wavelength HID which could utilize the strengths of different wavelengths to improve HID classifications. With

  12. Agricultural Monitoring in Northeastern Ontario, Canada, Using Multi-Temporal Polarimetric RADARSAT-2 Data

    Directory of Open Access Journals (Sweden)

    Jeffrey W. Cable

    2014-03-01

    Full Text Available The purpose of this research is to analyze how changes in acquisition time and incidence angle affect various C-band synthetic aperture radar (SAR polarimetric intensities, co-polarized phase information, polarimetric response plots and decomposition parameters for various crops typical of Northern Ontario, Canada. We examine how these parameters may be used to monitor the growth stages of five common cash crops, namely, barley (Hordeum vulgare, canola (Brassica napus, oat (Avena sativa, soybean (Glycine max and wheat (Triticum spp.. In total, nine RADARSAT-2 polarimetric images were analyzed across a 14-week period beginning in June and ending in September 2011 using two incidence angles of approximately 26° and 41°. As expected, the backscatter intensities for all targets were found to show a higher response when acquired at the steeper incidence angle (26°. All cash crop targets showed a rise and fall in backscatter response over the course of the growing season, coinciding with changing growth stages. Slight phase differences were observed for cereal crops, possibly due to one of the polarizations penetrating between the rows allowing double-bounce to occur. The polarimetric response plots and decompositions offered insight into the scattering mechanisms of each crop type, generally showing an increase in volume scattering as the crops reached maturity. Specifically, the contributions of the crops increased towards the volume scattering component and zones 4 and 2, as the crops matured in regards to the Freeman-Durden and Cloude-Pottier decompositions respectively. Overall, soybean and canola showed a more similar response in comparison to the cereal cash crops. Although the study focused on Northern Ontario, it is anticipated that these results would be relevant in investigations of multi-temporal RADARSAT-2 for agricultural zones with similar crop types.

  13. Astrocytic Insulin Signaling Couples Brain Glucose Uptake with Nutrient Availability.

    Science.gov (United States)

    García-Cáceres, Cristina; Quarta, Carmelo; Varela, Luis; Gao, Yuanqing; Gruber, Tim; Legutko, Beata; Jastroch, Martin; Johansson, Pia; Ninkovic, Jovica; Yi, Chun-Xia; Le Thuc, Ophelia; Szigeti-Buck, Klara; Cai, Weikang; Meyer, Carola W; Pfluger, Paul T; Fernandez, Ana M; Luquet, Serge; Woods, Stephen C; Torres-Alemán, Ignacio; Kahn, C Ronald; Götz, Magdalena; Horvath, Tamas L; Tschöp, Matthias H

    2016-08-11

    We report that astrocytic insulin signaling co-regulates hypothalamic glucose sensing and systemic glucose metabolism. Postnatal ablation of insulin receptors (IRs) in glial fibrillary acidic protein (GFAP)-expressing cells affects hypothalamic astrocyte morphology, mitochondrial function, and circuit connectivity. Accordingly, astrocytic IR ablation reduces glucose-induced activation of hypothalamic pro-opio-melanocortin (POMC) neurons and impairs physiological responses to changes in glucose availability. Hypothalamus-specific knockout of astrocytic IRs, as well as postnatal ablation by targeting glutamate aspartate transporter (GLAST)-expressing cells, replicates such alterations. A normal response to altering directly CNS glucose levels in mice lacking astrocytic IRs indicates a role in glucose transport across the blood-brain barrier (BBB). This was confirmed in vivo in GFAP-IR KO mice by using positron emission tomography and glucose monitoring in cerebral spinal fluid. We conclude that insulin signaling in hypothalamic astrocytes co-controls CNS glucose sensing and systemic glucose metabolism via regulation of glucose uptake across the BBB. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Four grams of glucose

    OpenAIRE

    Wasserman, David H.

    2008-01-01

    Four grams of glucose circulates in the blood of a person weighing 70 kg. This glucose is critical for normal function in many cell types. In accordance with the importance of these 4 g of glucose, a sophisticated control system is in place to maintain blood glucose constant. Our focus has been on the mechanisms by which the flux of glucose from liver to blood and from blood to skeletal muscle is regulated. The body has a remarkable capacity to satisfy the nutritional need for glucose, while ...

  15. IMPROVED SEARCH OF PRINCIPAL COMPONENT ANALYSIS DATABASES FOR SPECTRO-POLARIMETRIC INVERSION

    International Nuclear Information System (INIS)

    Casini, R.; Lites, B. W.; Ramos, A. Asensio; Ariste, A. López

    2013-01-01

    We describe a simple technique for the acceleration of spectro-polarimetric inversions based on principal component analysis (PCA) of Stokes profiles. This technique involves the indexing of the database models based on the sign of the projections (PCA coefficients) of the first few relevant orders of principal components of the four Stokes parameters. In this way, each model in the database can be attributed a distinctive binary number of 2 4n bits, where n is the number of PCA orders used for the indexing. Each of these binary numbers (indices) identifies a group of ''compatible'' models for the inversion of a given set of observed Stokes profiles sharing the same index. The complete set of the binary numbers so constructed evidently determines a partition of the database. The search of the database for the PCA inversion of spectro-polarimetric data can profit greatly from this indexing. In practical cases it becomes possible to approach the ideal acceleration factor of 2 4n as compared to the systematic search of a non-indexed database for a traditional PCA inversion. This indexing method relies on the existence of a physical meaning in the sign of the PCA coefficients of a model. For this reason, the presence of model ambiguities and of spectro-polarimetric noise in the observations limits in practice the number n of relevant PCA orders that can be used for the indexing

  16. Assessment of Polarimetric SAR Interferometry for Improving Ship Classification based on Simulated Data

    Directory of Open Access Journals (Sweden)

    Jordi J. Mallorqui

    2008-12-01

    Full Text Available This paper uses a complete and realistic SAR simulation processing chain, GRECOSAR, to study the potentialities of Polarimetric SAR Interferometry (POLInSAR in the development of new classification methods for ships. Its high processing efficiency and scenario flexibility have allowed to develop exhaustive scattering studies. The results have revealed, first, vessels’ geometries can be described by specific combinations of Permanent Polarimetric Scatterers (PePS and, second, each type of vessel could be characterized by a particular spatial and polarimetric distribution of PePS. Such properties have been recently exploited to propose a new Vessel Classification Algorithm (VCA working with POLInSAR data, which, according to several simulation tests, may provide promising performance in real scenarios. Along the paper, explanation of the main steps summarizing the whole research activity carried out with ships and GRECOSAR are provided as well as examples of the main results and VCA validation tests. Special attention will be devoted to the new improvements achieved, which are related to simulations processing a new and highly realistic sea surface model. The paper will show that, for POLInSAR data with fine resolution, VCA can help to classify ships with notable robustness under diverse and adverse observation conditions.

  17. Effects of surface materials on polarimetric-thermal measurements: applications to face recognition.

    Science.gov (United States)

    Short, Nathaniel J; Yuffa, Alex J; Videen, Gorden; Hu, Shuowen

    2016-07-01

    Materials, such as cosmetics, applied to the face can severely inhibit biometric face-recognition systems operating in the visible spectrum. These products are typically made up of materials having different spectral properties and color pigmentation that distorts the perceived shape of the face. The surface of the face emits thermal radiation, due to the living tissue beneath the surface of the skin. The emissivity of skin is approximately 0.99; in comparison, oil- and plastic-based materials, commonly found in cosmetics and face paints, have an emissivity range of 0.9-0.95 in the long-wavelength infrared part of the spectrum. Due to these properties, all three are good thermal emitters and have little impact on the heat transferred from the face. Polarimetric-thermal imaging provides additional details of the face and is also dependent upon the thermal radiation from the face. In this paper, we provide a theoretical analysis on the thermal conductivity of various materials commonly applied to the face using a metallic sphere. Additionally, we observe the impact of environmental conditions on the strength of the polarimetric signature and the ability to recover geometric details. Finally, we show how these materials degrade the performance of traditional face-recognition methods and provide an approach to mitigating this effect using polarimetric-thermal imaging.

  18. Polarimetric infrared imaging simulation of a synthetic sea surface with Mie scattering.

    Science.gov (United States)

    He, Si; Wang, Xia; Xia, Runqiu; Jin, Weiqi; Liang, Jian'an

    2018-03-01

    A novel method to simulate the polarimetric infrared imaging of a synthetic sea surface with atmospheric Mie scattering effects is presented. The infrared emission, multiple reflections, and infrared polarization of the sea surface and the Mie scattering of aerosols are all included for the first time. At first, a new approach to retrieving the radiative characteristics of a wind-roughened sea surface is introduced. A two-scale method of sea surface realization and the inverse ray tracing of light transfer calculation are combined and executed simultaneously, decreasing the consumption of time and memory dramatically. Then the scattering process that the infrared light emits from the sea surface and propagates in the aerosol particles is simulated with a polarized light Monte Carlo model. Transformations of the polarization state of the light are calculated with the Mie theory. Finally, the polarimetric infrared images of the sea surface of different environmental conditions and detection parameters are generated based on the scattered light detected by the infrared imaging polarimeter. The results of simulation examples show that our polarimetric infrared imaging simulation can be applied to predict the infrared polarization characteristics of the sea surface, model the oceanic scene, and guide the detection in the oceanic environment.

  19. The use of two continuous glucose sensors during and after surgery

    NARCIS (Netherlands)

    Vriesendorp, T. M.; DeVries, J. H.; Holleman, F.; Dzoljic, M.; Hoekstra, J. B. L.

    2005-01-01

    BACKGROUND: Maintaining plasma glucose between 80 and 120 mg/dL is beneficial for patients admitted to a surgical intensive care unit, but requires frequent glucose monitoring to ensure adequacy of treatment and detection of hypoglycemia. We examined whether continuous glucose sensing is feasible

  20. Probabilistic discrimination between liquid rainfall events, hailstorms, biomass burning and industrial fires from C-Band Radar Polarimetric Variables

    Science.gov (United States)

    Valencia, J. M.; Sepúlveda, J.; Hoyos, C.; Herrera, L.

    2017-12-01

    Characterization and identification of fire and hailstorm events using weather radar data in a tropical complex topography region is an important task in risk management and agriculture. Polarimetric variables from a C-Band Dual polarization weather radar have potential uses in particle classification, due to the relationship their sensitivity to shape, spatial orientation, size and fall behavior of particles. In this sense, three forest fires and two chemical fires were identified for the Áburra Valley regions. Measurements were compared between each fire event type and with typical data radar retrievals for liquid precipitation events. Results of this analysis show different probability density functions for each type of event according to the particles present in them. This is very important and useful result for early warning systems to avoid precipitation false alarms during fire events within the study region, as well as for the early detection of fires using radar retrievals in remote cases. The comparative methodology is extended to hailstorm cases. Complementary sensors like laser precipitation sensors (LPM) disdrometers and meteorological stations were used to select dates of solid precipitation occurrence. Then, in this dates weather radar data variables were taken in pixels surrounding the stations and solid precipitation polar values were statistically compared with liquid precipitation values. Spectrum precipitation measured by LPM disdrometer helps to define typical features like particles number, fall velocities and diameters for both precipitation types. In addition, to achieve a complete hailstorm characterization, other meteorological variables were analyzed: wind field from meteorological stations and radar wind profiler, profiling data from Micro Rain Radar (MRR), and thermodynamic data from a microwave radiometer.

  1. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for high blood glucose (blood sugar). High ... We Are Research Leaders We Support Your Doctor Student Resources Patient Access to Research Research Resources Practice ...

  2. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Español Hyperglycemia (High Blood Glucose) Hyperglycemia is the technical term for high blood glucose (blood sugar). High ... Type 2 Diabetes program to get help and support during your first year. Featured Book Type 2 ...

  3. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... and eAG Hypoglycemia (Low blood glucose) Hyperglycemia (High blood glucose) Dawn Phenomenon Checking for Ketones Tight Diabetes Control donate en -- A Future Without Diabetes - a-future- ...

  4. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Blood Pressure Physical Activity High Blood Glucose My Health Advisor Tools To Know Your Risk Alert Day ... DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing ...

  5. Glucose-6-phosphate dehydrogenase

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003671.htm Glucose-6-phosphate dehydrogenase test To use the sharing features on this page, please enable JavaScript. Glucose-6-phosphate dehydrogenase (G6PD) is a protein that ...

  6. Glucose test (image)

    Science.gov (United States)

    ... person with diabetes constantly manages their blood's sugar (glucose) levels. After a blood sample is taken and tested, it is determined whether the glucose levels are low or high. Following your health ...

  7. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... symptoms include the following: High blood glucose High levels of sugar in the urine Frequent urination Increased ... you should check and what your blood glucose levels should be. Checking your blood and then treating ...

  8. Classification and Monitoring of Reed Belts Using Dual-Polarimetric TerraSAR-X Time Series

    Directory of Open Access Journals (Sweden)

    Iris Heine

    2016-06-01

    Full Text Available Synthetic aperture radar polarimetry (PolSAR and polarimetric decomposition techniques have proven to be useful tools for wetland mapping. In this study we classify reed belts and monitor their phenological changes at a natural lake in northeastern Germany using dual-co-polarized (HH, VV TerraSAR-X time series. The time series comprises 19 images, acquired between August 2014 and May 2015, in ascending and descending orbit. We calculated different polarimetric indices using the HH and VV intensities, the dual-polarimetric coherency matrix including dominant and mean alpha scattering angles, and entropy and anisotropy (normalized eigenvalue difference as well as combinations of entropy and anisotropy for the analysis of the scattering scenarios. The image classifications were performed with the random forest classifier and validated with high-resolution digital orthophotos. The time series analysis of the reed belts revealed significant seasonal changes for the double-bounce–sensitive parameters (intensity ratio HH/VV and intensity difference HH-VV, the co-polarimetric coherence phase and the dominant and mean alpha scattering angles and in the dual-polarimetric coherence (amplitude, anisotropy, entropy, and anisotropy-entropy combinations; whereas in summer dense leaves cause volume scattering, in winter, after leaves have fallen, the reed stems cause predominately double-bounce scattering. Our study showed that the five most important parameters for the classification of reed are the intensity difference HH-VV, the mean alpha scattering angle, intensity ratio HH/VV, and the coherence (phase. Due to the better separation of reed and other vegetation (deciduous forest, coniferous forest, meadow, winter acquisitions are preferred for the mapping of reed. Multi-temporal stacks of winter images performed better than summer ones. The combination of ascending and descending images also improved the result as it reduces the influence of the sensor

  9. [Blood glucose self monitoring].

    Science.gov (United States)

    Wascher, Thomas C; Stechemesser, Lars

    2016-04-01

    Self monitoring of blood glucose contributes to the integrated management of diabetes mellitus. It, thus, should be available for all patients with diabetes mellitus type-1 and type-2. Self monitoring of blood glucose improves patients safety, quality of life and glucose control. The current article represents the recommendations of the Austrian Diabetes Association for the use of blood glucose self monitoring according to current scientific evidence.

  10. Calibration of Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) polarization measurements, and in-flight comparisons with the Research Scanning Polarimeter (RSP) and the Spectropolarimeter for Planetary EXploration (SPEX)

    Science.gov (United States)

    van Harten, G.; Diner, D. J.; Rheingans, B. E.; Daugherty, B. J.; Xu, F.; Bull, M. A.; Tkatcheva, I. N.; Garay, M. J.; Seidel, F.; Chipman, R. A.; Smit, M.

    2016-12-01

    The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is a remote sensing instrument for the characterization of atmospheric aerosols and clouds. AirMSPI, flying onboard the NASA ER-2 aircraft at 20 km altitude, participates in field campaigns since 2013, including ORACLES (2016). The pushbroom camera is mounted on a programmable, motorized gimbal for multi-angle observations at 10x10 m2 resolution. Eight spectral bands within 355-935 nm are recorded, 3 of which also measure linear polarization. Photoelastic modulators (PEMs) encode the polarized and total intensities in each polarimetric pixel as the amplitude and offset of a modulated intensity pattern, such that the ratio of the two is insensitive to pixel-to-pixel differences. This technique, developed to enable the high-accuracy imaging polarimetry required for aerosol species discrimination, will also be applied in the Multi-Angle Imager for Aerosols (MAIA) satellite instrument. We present the calibration and accuracy validation of AirMSPI polarization measurements. The main calibration, describing the instrument's response to any degree (DoLP) and angle of linear polarization, is performed in the lab using a recently updated, carefully designed and characterized polarization state generator (PSG-2). Validation measurements using an independent polarimeter show agreement in DoLP to within 0.001 for several DoLPs across the 0-1 range. The PEMs' retardances and phases, which are different and not necessarily stable in flight, are extracted from measurements of the on-board validator, a partially polarized light source located inside the instrument housing, which is viewed before and after each target. Although this calibration does not rely on the validator's DoLP, and the validator was not designed for DoLP calibration, the frequent measurements of its DoLP provide an upper limit for AirMSPI's in-flight polarimetric stability, which is 0.001. A correction for the actual PEM retardances and phases in the

  11. Make Sense?

    OpenAIRE

    Gyrd-Jones, Richard; Törmälä, Minna

    2017-01-01

    Purpose: An important part of how we sense a brand is how we make sense of a brand. Sense-making is naturally strongly connected to how we cognize about the brand. But sense-making is concerned with multiple forms of knowledge that arise from our interpretation of the brand-related stimuli: Declarative, episodic, procedural and sensory. Knowledge is given meaning through mental association (Keller, 1993) and / or symbolic interaction (Blumer, 1969). These meanings are centrally related to ind...

  12. Remote Sensing

    Indian Academy of Sciences (India)

    netic radiation as a medium of interaction. Space borne remote sensing is fast emerging as a front running provider of information on natural resources in a spatial format. This article briefly discusses the physical basis of remote sensing, how information is extracted from images and various applications of remote sensing.

  13. Standard Format for Chromatographic-polarimetric System small samples assessment

    International Nuclear Information System (INIS)

    Naranjo, S.; Fajer, V.; Fonfria, C.; Patinno, R.

    2012-01-01

    The treatment of samples containing optically active substances to be evaluated as part of quality control of raw material entering industrial process, and also during the modifications exerted on it to obtain the desired final composition is still and unsolved problem for many industries. That is the case of sugarcane industry. Sometimes the troubles implied are enlarged because samples to be evaluated are not bigger than one milliliter. Reduction of gel beds in G-10 and G-50 chromatographic columns having an inner diameter of 16 mm, instead of 25, and bed heights adjustable to requirements by means of sliding stoppers to increase analytical power were evaluated with glucose and sucrose standards in concentrations from 1 to 10 g/dL, using aliquots of 1 ml without undesirable dilutions that could affect either detection or chromatographic profile. Assays with seaweed extracts gave good results that are shown. It is established the advantage to know concentration of a separated substance by the height of its peak and the savings in time and reagents resulting . Sample expanded uncertainty in both systems is compared. It is also presented several programs for data acquisition, storing and processing. (Author)

  14. Glucose screening tests during pregnancy

    Science.gov (United States)

    Oral glucose tolerance test - pregnancy; OGTT - pregnancy; Glucose challenge test - pregnancy; Gestational diabetes - glucose screening ... During the first step, you will have a glucose screening test: You DO NOT need to prepare ...

  15. Performance Considerations for the SIMPL Single Photon, Polarimetric, Two-Color Laser Altimeter as Applied to Measurements of Forest Canopy Structure and Composition

    Science.gov (United States)

    Dabney, Philip W.; Harding, David J.; Valett, Susan R.; Vasilyev, Aleksey A.; Yu, Anthony W.

    2012-01-01

    The Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) is a multi-beam, micropulse airborne laser altimeter that acquires active and passive polarimetric optical remote sensing measurements at visible and near-infrared wavelengths. SIMPL was developed to demonstrate advanced measurement approaches of potential benefit for improved, more efficient spaceflight laser altimeter missions. SIMPL data have been acquired for wide diversity of forest types in the summers of 2010 and 2011 in order to assess the potential of its novel capabilities for characterization of vegetation structure and composition. On each of its four beams SIMPL provides highly-resolved measurements of forest canopy structure by detecting single-photons with 15 cm ranging precision using a narrow-beam system operating at a laser repetition rate of 11 kHz. Associated with that ranging data SIMPL provides eight amplitude parameters per beam unlike the single amplitude provided by typical laser altimeters. Those eight parameters are received energy that is parallel and perpendicular to that of the plane-polarized transmit pulse at 532 nm (green) and 1064 nm (near IR), for both the active laser backscatter retro-reflectance and the passive solar bi-directional reflectance. This poster presentation will cover the instrument architecture and highlight the performance of the SIMPL instrument with examples taken from measurements for several sites with distinct canopy structures and compositions. Specific performance areas such as probability of detection, after pulsing, and dead time, will be highlighted and addressed, along with examples of their impact on the measurements and how they limit the ability to accurately model and recover the canopy properties. To assess the sensitivity of SIMPL's measurements to canopy properties an instrument model has been implemented in the FLIGHT radiative transfer code, based on Monte Carlo simulation of photon transport. SIMPL data collected in 2010 over

  16. Mapping Plastic-Mulched Farmland with C-Band Full Polarization SAR Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Hasituya

    2017-12-01

    Full Text Available Plastic mulching is an important technology in agricultural production both in China and the rest of the world. In spite of its benefit of increasing crop yields, the booming expansion of the plastic mulching area has been changing the landscape patterns and affecting the environment. Accurate and effective mapping of Plastic-Mulched Farmland (PMF can provide useful information for leveraging its advantages and disadvantages. However, mapping the PMF with remote sensing is still challenging owing to its varying spectral characteristics with the crop growth and geographic spatial division. In this paper, we investigated the potential of Radarsat-2 data for mapping PMF. We obtained the backscattering intensity of different polarizations and multiple polarimetric decomposition descriptors. These remotely-sensed information was used as input features for Random Forest (RF and Support Vector Machine (SVM classifiers. The results indicated that the features from Radarsat-2 data have great potential for mapping PMF. The overall accuracies of PMF mapping with Radarsat-2 data were close to 75%. Although the classification accuracy with the back-scattering intensity information alone was relatively lower owing to the inherent speckle noise in SAR data, it has been improved significantly by introducing the polarimetric decomposition descriptors. The accuracy was nearly 75%. In addition, the features derived from the Entropy/Anisotropy/Alpha (H/A/Alpha polarimetric decomposition, such as Alpha, entropy, and so on, made a greater contribution to PMF mapping than the Freeman decomposition, Krogager decomposition and the Yamaguchi4 decomposition. The performances of different classifiers were also compared. In this study, the RF classifier performed better than the SVM classifier. However, it is expected that the classification accuracy of PMF with SAR remote sensing data can be improved by combining SAR remote sensing data with optical remote sensing data.

  17. A Classification Method Based on Polarimetric Entropy and GEV Mixture Model for Intertidal Area of PolSAR Image

    Directory of Open Access Journals (Sweden)

    She Xiaoqiang

    2017-10-01

    Full Text Available This paper proposes a classification method for the intertidal area using quad-polarimetric synthetic aperture radar data. In this paper, a systematic comparison of four well-known multipolarization features is provided so that appropriate features can be selected based on the characteristics of the intertidal area. Analysis result shows that the two most powerful multipolarization features are polarimetric entropy and anisotropy. Furthermore, through our detailed analysis of the scattering mechanisms of the polarimetric entropy, the Generalized Extreme Value (GEV distribution is employed to describe the statistical characteristics of the intertidal area based on the extreme value theory. Consequently, a new classification method is proposed by combining the GEV Mixture Models and the EM algorithm. Finally, experiments are performed on the Radarsat-2 quad-polarization data of the Dongtan intertidal area, Shanghai, to validate our method.

  18. Estimating the Concentration of Large Raindrops from Polarimetric Radar and Disdrometer Observations

    Science.gov (United States)

    Carey, Lawrence D.; Petersen, Walter A; Gatlink, Patrick N.

    2013-01-01

    Estimation of rainfall integral parameters, including radar observables, and empirical relations between them are sensitive to the truncation of the drop size distribution (DSD), particularly at the large drop end. The sensitivity of rainfall integral parameters to the maximum drop diameter (D(sub max)) is exacerbated at C-band since resonance effects are pronounced for large drops in excess of 5 mm diameter (D). Due to sampling limitations, it is often difficult to reliably estimate D(sub max) with disdrometers. The resulting uncertainties in D(sub max0 potentially increase errors in radar retrieval methods, particularly at C-band, that rely on disdrometer observations for DSD input to radar models. In fact, D(sub max) is typically an assumed DSD parameter in the development of radar retrieval methods. Because of these very uncertainties, it is difficult to independently confirm disdrometer estimates of D(sub max) with polarimetric radar observations. A couple of approaches can be taken to reduce uncertainty in large drop measurement. Longer integration times can be used for the collection of larger disdrometer samples. However, integration periods must be consistent with a radar resolution volume (RRV) and the temporal and spatial scales of the physical processes affecting the DSD therein. Multiple co-located disdrometers can be combined into a network to increase the sample size within a RRV. However, over a reasonable integration period, a single disdrometer sample volume is many orders of magnitudes less than a RRV so it is not practical to devise a network of disdrometers that has an equivalent volume to a typical RRV. Since knowledge of DSD heterogeneity and large drop occurrence in time and space is lacking, the specific accuracy or even general representativeness of disdrometer based D(sub max) and large drop concentration estimates within a RRV are currently unknown. To address this complex issue, we begin with a simpler question. Is the frequency of

  19. Atmospheric and precipitation sounding with polarimetric radio-occultations aboard PAZ LEO

    Science.gov (United States)

    Padulles, Ramon; Cardellach, Estel; Tomás, Sergio; Oliveras, Santi; Rius, Antonio; de la Torre, Manuel; Turk, Joseph; Ao, Chi; Kursinski, Robert; Shreiner, Bill; Ector, Dave; Cucurull, Lidia; Wickert, Jens

    2015-04-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) Radio-Occultation (RO) payload on board of the Spanish Earth Observation satellite PAZ. This will be a new technique that has never been tested before, that aims to improve the knowledge of the precipitation through simultaneous thermodynamic and vertical rain profiles. The concept is similar to that used in some polarimetric weather radars: to measure the differential phase shift between the two polarimetric antennas, although here we will use the forward scattering geometry instead of the backscattering.The depolarization effect increases as the propagation line aligns with the plane of the drops' flattening (nominally perpendicular to the local gravity, i.e., parallel to the local horizon). The RO signals cross the lower troposphere tangentially, i.e., along the local horizon, which should maximize the depolarization effect. The satellite launch is scheduled for March 2015, and it will be followed by a 6-month commissioning phase period and has an expected life of 7 years, with a goal of 10 years. A sensitivity analysis have been performed, showing that we should be able to detect the 90% of all the events with along-ray averaged rain rate higher than 5 mm/h. Also, a ground field campaign has been conducted prior to the launch of the satellite. Results from the campaign also show a good correlation between phase shifts increases and heavy rain events. We will present here the status of the mission, which will have been launched few weeks before the EGU, together with some preliminary data analysis from both the actual satellite data and the prior-to-launch work.

  20. A test statistic in the complex Wishart distribution and its application to change detection in polarimetric SAR data

    DEFF Research Database (Denmark)

    Conradsen, Knut; Nielsen, Allan Aasbjerg; Schou, Jesper

    2003-01-01

    . Based on this distribution, a test statistic for equality of two such matrices and an associated asymptotic probability for obtaining a smaller value of the test statistic are derived and applied successfully to change detection in polarimetric SAR data. In a case study, EMISAR L-band data from April 17...... to HH, VV, or HV data alone, the derived test statistic reduces to the well-known gamma likelihood-ratio test statistic. The derived test statistic and the associated significance value can be applied as a line or edge detector in fully polarimetric SAR data also....

  1. A New Ka-Band Scanning Radar Facility: Polarimetric and Doppler Spectra Measurements of Snow Events

    Science.gov (United States)

    Oue, M.; Kollias, P.; Luke, E. P.; Mead, J.

    2017-12-01

    Polarimetric radar analyses offer the capability of identification of ice hydrometeor species as well as their spatial distributions. In addition to polarimetric parameter observations, Doppler spectra measurements offer unique insights into ice particle properties according to particle fall velocities. In particular, millimeter-wavelength radar Doppler spectra can reveal supercooled liquid cloud droplets embedded in ice precipitation clouds. A Ka-band scanning polarimetric radar, named KASPR, was installed in an observation facility at Stony Brook University, located 22 km west of the KOKX NEXRAD radar at Upton, NY. The KASPR can measure Doppler spectra and full polarimetric variables, including radar reflectivity, differential reflectivity (ZDR), differential phase (φDP), specific differential phase (KDP), correlation coefficient (ρhv), and linear depolarization ratio (LDR). The facility also includes a micro-rain radar and a microwave radiometer capable of measuring reflectivity profiles and integrated liquid water path, respectively. The instruments collected initial datasets during two snowstorm events and two snow shower events in March 2017. The radar scan strategy was a combination of PPI scans at 4 elevation angles (10, 20, 45, and 60°) and RHI scans in polarimetry mode, and zenith pointing with Doppler spectra collection. During the snowstorm events the radar observed relatively larger ZDR (1-1.5 dB) and enhanced KDP (1-2 ° km-1) at heights corresponding to a plate/dendrite crystal growth regime. The Doppler spectra showed that slower-falling particles ( 1 m s-1). The weakly increased ZDR could be produced by large, faster falling particles such as quasi-spherical aggregates, while the enhanced KDP could be produced by highly-oriented oblate, slowly-falling particles. Below 2 km altitude, measurements of dual wavelength ratio (DWR) based on Ka and S-band reflectivities from the KASPR and NEXRAD radars were available. Larger DWR (>10 dB) suggested

  2. Identification of hydrometeor mixtures in polarimetric radar measurements and their linear de-mixing

    Science.gov (United States)

    Besic, Nikola; Ventura, Jordi Figueras i.; Grazioli, Jacopo; Gabella, Marco; Germann, Urs; Berne, Alexis

    2017-04-01

    The issue of hydrometeor mixtures affects radar sampling volumes without a clear dominant hydrometeor type. Containing a number of different hydrometeor types which significantly contribute to the polarimetric variables, these volumes are likely to occur in the vicinity of the melting layer and mainly, at large distance from a given radar. Motivated by potential benefits for both quantitative and qualitative applications of dual-pol radar, we propose a method for the identification of hydrometeor mixtures and their subsequent linear de-mixing. This method is intrinsically related to our recently proposed semi-supervised approach for hydrometeor classification. The mentioned classification approach [1] performs labeling of radar sampling volumes by using as a criterion the Euclidean distance with respect to five-dimensional centroids, depicting nine hydrometeor classes. The positions of the centroids in the space formed by four radar moments and one external parameter (phase indicator), are derived through a technique of k-medoids clustering, applied on a selected representative set of radar observations, and coupled with statistical testing which introduces the assumed microphysical properties of the different hydrometeor types. Aside from a hydrometeor type label, each radar sampling volume is characterized by an entropy estimate, indicating the uncertainty of the classification. Here, we revisit the concept of entropy presented in [1], in order to emphasize its presumed potential for the identification of hydrometeor mixtures. The calculation of entropy is based on the estimate of the probability (pi ) that the observation corresponds to the hydrometeor type i (i = 1,ṡṡṡ9) . The probability is derived from the Euclidean distance (di ) of the observation to the centroid characterizing the hydrometeor type i . The parametrization of the d → p transform is conducted in a controlled environment, using synthetic polarimetric radar datasets. It ensures balanced

  3. Discussion on Application of Polarimetric Synthetic Aperture Radar in Marine Surveillance

    Directory of Open Access Journals (Sweden)

    Zhang Jie

    2016-12-01

    Full Text Available Synthetic Aperture Radar (SAR, an important earth observation sensor, has been used in a wide range of applications for land and marine surveillance. Polarimetric SAR (PolSAR can obtain abundant scattering information of a target to improve the ability of target detection, classification, and quantitative inversion. In this paper, the important role of PolSAR in ocean monitoring is discussed with factors such as sea ice, ships, oil spill, waves, internal waves, and seabed topography. Moreover, the future development direction of PolSAR is put forward to get an inspiration for further research of PolSAR in marine surveillance applications.

  4. Microphysical properties of frozen particles inferred from Global Precipitation Measurement (GPM) Microwave Imager (GMI) polarimetric measurements

    Science.gov (United States)

    Gong, Jie; Wu, Dong L.

    2017-02-01

    Scattering differences induced by frozen particle microphysical properties are investigated, using the vertically (V) and horizontally (H) polarized radiances from the Global Precipitation Measurement (GPM) Microwave Imager (GMI) 89 and 166 GHz channels. It is the first study on frozen particle microphysical properties on a global scale that uses the dual-frequency microwave polarimetric signals.From the ice cloud scenes identified by the 183.3 ± 3 GHz channel brightness temperature (Tb), we find that the scattering by frozen particles is highly polarized, with V-H polarimetric differences (PDs) being positive throughout the tropics and the winter hemisphere mid-latitude jet regions, including PDs from the GMI 89 and 166 GHz TBs, as well as the PD at 640 GHz from the ER-2 Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR) during the TC4 campaign. Large polarization dominantly occurs mostly near convective outflow regions (i.e., anvils or stratiform precipitation), while the polarization signal is small inside deep convective cores as well as at the remote cirrus region. Neglecting the polarimetric signal would easily result in as large as 30 % error in ice water path retrievals. There is a universal bell curve in the PD-TBV relationship, where the PD amplitude peaks at ˜ 10 K for all three channels in the tropics and increases slightly with latitude (2-4 K). Moreover, the 166 GHz PD tends to increase in the case where a melting layer is beneath the frozen particles aloft in the atmosphere, while 89 GHz PD is less sensitive than 166 GHz to the melting layer. This property creates a unique PD feature for the identification of the melting layer and stratiform rain with passive sensors.Horizontally oriented non-spherical frozen particles are thought to produce the observed PD because of different ice scattering properties in the V and H polarizations. On the other hand, turbulent mixing within deep convective cores inevitably promotes the random

  5. Processing and Analysis of Polarimetric Ship Signatures from MARSIE: Report on Results for Polar Epsilon

    Science.gov (United States)

    2006-10-01

    observations de la surface équivalente radar de navires cibles pour les canaux de copolarisation et de polarisation croisée, la réduction de la...motion, environmental conditions, etc. on the observed polarimetric signatures; • The differences in the elemental scatterer distributions among the...calculée pour plusieurs navires. Les valeurs estimées de SER totale pour les canaux HV et VH étaient d’environ 10 dB inférieures aux valeurs

  6. Fitting a Two-Component Scattering Model to Polarimetric SAR Data from Forests

    Science.gov (United States)

    Freeman, Anthony

    2007-01-01

    Two simple scattering mechanisms are fitted to polarimetric synthetic aperture radar (SAR) observations of forests. The mechanisms are canopy scatter from a reciprocal medium with azimuthal symmetry and a ground scatter term that can represent double-bounce scatter from a pair of orthogonal surfaces with different dielectric constants or Bragg scatter from a moderately rough surface, which is seen through a layer of vertically oriented scatterers. The model is shown to represent the behavior of polarimetric backscatter from a tropical forest and two temperate forest sites by applying it to data from the National Aeronautic and Space Agency/Jet Propulsion Laboratory's Airborne SAR (AIRSAR) system. Scattering contributions from the two basic scattering mechanisms are estimated for clusters of pixels in polarimetric SAR images. The solution involves the estimation of four parameters from four separate equations. This model fit approach is justified as a simplification of more complicated scattering models, which require many inputs to solve the forward scattering problem. The model is used to develop an understanding of the ground-trunk double-bounce scattering that is present in the data, which is seen to vary considerably as a function of incidence angle. Two parameters in the model fit appear to exhibit sensitivity to vegetation canopy structure, which is worth further exploration. Results from the model fit for the ground scattering term are compared with estimates from a forward model and shown to be in good agreement. The behavior of the scattering from the ground-trunk interaction is consistent with the presence of a pseudo-Brewster angle effect for the air-trunk scattering interface. If the Brewster angle is known, it is possible to directly estimate the real part of the dielectric constant of the trunks, a key variable in forward modeling of backscatter from forests. It is also shown how, with a priori knowledge of the forest height, an estimate for the

  7. Measuring brain glucose phosphorylation with labeled glucose

    International Nuclear Information System (INIS)

    Brondsted, H.E.; Gjedde, A.

    1988-01-01

    This study tested whether glucose labeled at the C-6 position generates metabolites that leave brain so rapidly that C-6-labeled glucose cannot be used to measure brain glucose phosphorylation (CMRGlc). In pentobarbital-anesthetized rats, the parietal cortex uptake of [ 14 C]glucose labeled in the C-6 position was followed for times ranging from 10 s to 60 min. We subtracted the observed radioactivity from the radioactivity expected with no loss of labeled metabolites from brain by extrapolation of glucose uptake in an initial period when loss was negligible. The observed radioactivity was a monoexponentially declining function of the total radioactivity expected in the absence of metabolite loss. The constant of decline was 0.0077.min-1 for parietal cortex. Metabolites were lost from the beginning of the experiment. However, with correction for the loss of labeled metabolites, it was possible to determine an average CMRGlc between 4 and 60 min of circulation of 64 +/- 4 (SE; n = 49) mumol.hg-1.min-1

  8. Neural pathways that control the glucose counterregulatory response

    Directory of Open Access Journals (Sweden)

    Tony eVerberne

    2014-02-01

    Full Text Available Glucose is an essential metabolic substrate for all bodily tissues. The brain depends particularly on a constant supply of glucose to satisfy its energy demands. Fortunately, a complex physiological system has evolved to keep blood glucose at a constant level. The consequences of poor glucose homeostasis are well-known: hyperglycaemia associated with uncontrolled diabetes can lead to cardiovascular disease, neuropathy and nephropathy, while hypoglycaemia can lead to convulsions, loss of consciousness, coma and even death. The glucose counterregulatory response involves detection of declining plasma glucose levels and secretion of several hormones including glucagon, adrenaline, cortisol and growth hormone to orchestrate the recovery from hypoglycaemia. Low blood glucose leads to a low brain glucose level that is detected by glucose-sensing neurons located in several brain regions such as the ventromedial hypothalamus, the perifornical region of the lateral hypothalamus, the arcuate nucleus and in several hindbrain regions. This review will describe the importance of the glucose counterregulatory system and what is known of the neurocircuitry that underpins it.

  9. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Complications Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing ...

  10. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  11. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Complications Neuropathy Foot Complications DKA (Ketoacidosis) & Ketones Kidney Disease (Nephropathy) Gastroparesis Mental Health Step On Up Treatment & Care Blood Glucose Testing Medication Doctors, Nurses & More ...

  12. Robust Sparse Sensing Using Weather Radar

    Science.gov (United States)

    Mishra, K. V.; Kruger, A.; Krajewski, W. F.; Xu, W.

    2014-12-01

    The ability of a weather radar to detect weak echoes is limited by the presence of noise or unwanted echoes. Some of these unwanted signals originate externally to the radar system, such as cosmic noise, radome reflections, interference from co-located radars, and power transmission lines. The internal source of noise in microwave radar receiver is mainly thermal. The thermal noise from various microwave devices in the radar receiver tends to lower the signal-to-noise ratio, thereby masking the weaker signals. Recently, the compressed sensing (CS) technique has emerged as a novel signal sampling paradigm that allows perfect reconstruction of signals sampled at frequencies lower than the Nyquist rate. Many radar and remote sensing applications require efficient and rapid data acquisition. The application of CS to weather radars may allow for faster target update rates without compromising the accuracy of target information. In our previous work, we demonstrated recovery of an entire precipitation scene from its compressed-sensed version by using the matrix completion approach. In this study, we characterize the performance of such a CS-based weather radar in the presence of additive noise. We use a signal model where the precipitation signals form a low-rank matrix that is corrupted with (bounded) noise. Using recent advances in algorithms for matrix completion from few noisy observations, we reconstruct the precipitation scene with reasonable accuracy. We test and demonstrate our approach using the data collected by Iowa X-band Polarimetric (XPOL) weather radars.

  13. In vivo glucose monitoring using dual-wavelength polarimetry to overcome corneal birefringence in the presence of motion.

    Science.gov (United States)

    Pirnstill, Casey W; Malik, Bilal H; Gresham, Vincent C; Coté, Gerard L

    2012-09-01

    Over the past 35 years considerable research has been performed toward the investigation of noninvasive and minimally invasive glucose monitoring techniques. Optical polarimetry is one noninvasive technique that has shown promise as a means to ascertain blood glucose levels through measuring the glucose concentrations in the anterior chamber of the eye. However, one of the key limitations to the use of optical polarimetry as a means to noninvasively measure glucose levels is the presence of sample noise caused by motion-induced time-varying corneal birefringence. In this article our group presents, for the first time, results that show dual-wavelength polarimetry can be used to accurately detect glucose concentrations in the presence of motion-induced birefringence in vivo using New Zealand White rabbits. In total, nine animal studies (three New Zealand White rabbits across three separate days) were conducted. Using the dual-wavelength optical polarimetric approach, in vivo, an overall mean average relative difference of 4.49% (11.66 mg/dL) was achieved with 100% Zone A+B hits on a Clarke error grid, including 100% falling in Zone A. The results indicate that dual-wavelength polarimetry can effectively be used to significantly reduce the noise due to time-varying corneal birefringence in vivo, allowing the accurate measurement of glucose concentration in the aqueous humor of the eye and correlating that with blood glucose.

  14. Polarimetric SAR tomography in the X-band by continuous wave multi-baseline SAR tracks in a convex optimization approach

    Science.gov (United States)

    Biondi, Filippo; Sarri, Antonio; Fiori, Luca; Dell'Omodarme, Kevin

    2014-10-01

    SAR Tomography is the extension of the conventional interferometric radar signal processing, extended in the height dimension. In order to improve the vertical resolution with respect to the classical Fourier methods, high resolution approaches, based on the Convex Optimization (CVX), has been implemented. This methods recast in the Compressed Sensing (CS) framework that optimize tomographic smooth profiles via atomic decomposition, in order to obtain sparsity. The optimum solution has been estimated by Interior Point Methods (IPM). The problem for such kind of signal processing is that the tomographic phase information may be suppressed and only the optimized energy information is available. In this paper we propose a method in order to estimate an optimized spectra and phase information projecting each vector components of each tomographic resolution cell spanned in the real and the imaginary component. The tomographic solutions has been performed by processing multi-baseline SAR datasets, in a full polarimetric mode, acquired by a portable small Continuous Wave (CW) radar in the X band.

  15. Remote Sensing

    Indian Academy of Sciences (India)

    Rangnath R Navalgund, after working for more than two decades at the. Space Applications. Centre (ISRO),. Ahmedabad has moved over to the National. Remote Sensing Agency,. Department of Space,. Hyderabad, as its. Director since May 2001. Definition of Indian spacebome remote sensing missions and formulation of ...

  16. Applications of fluorescent biosensors for non-invasive glucose monitoring

    OpenAIRE

    Bruen, Danielle; Delaney, Colm; Florea, Larisa; Diamond, Dermot

    2016-01-01

    Diabetes is a widespread disease, whereby the body is incapable of regulating the metabolism of glucose1. As a result, this disorder leads to severe health effects such as blindness, kidney failure and stroke1-2, where monitoring glucose has proven to prevent some of these undesired side effects. Current monitoring methods for diabetes are either invasive or non-continuous, where Brooks et al have introduced contact lenses, on the cover of ACS Nanomaterials, as a sensing platform for noninvas...

  17. Validation of Forested Inundation Extent Revealed by L-Band Polarimetric and Interferometric SAR Data

    Science.gov (United States)

    Chapman, Bruce; Celi, Jorge; Hamilton, Steve; McDonald, Kyle

    2013-01-01

    UAVSAR, NASA's airborne Synthetic Aperture Radar (SAR), conducted an extended observational campaign in Central and South America in March 2013, primarily related to volcanic deformations along the Andean Mountain Range but also including a large number of flights studying other scientific phenomena. During this campaign, the L-Band SAR collected data over the Napo River in Ecuador. The objectives of this experiment were to acquire polarimetric and interferometric L-Band SAR data over an inundated tropical forest in Ecuador simultaneously with on-the-ground field work ascertaining the extent of inundation, and to then derive from this data a quantitative estimate for the error in the SAR-derived inundation extent. In this paper, we will first describe the processing and preliminary analysis of the SAR data. The polarimetric SAR data will be classified by land cover and inundation state. The interferometric SAR data will be used to identify those areas where change in inundation extent occurred, and to measure the change in water level between two observations separated by a week. Second, we will describe the collection of the field estimates of inundation, and have preliminary comparisons of inundation extent measured in the field field versus that estimated from the SAR data.

  18. Polarimetric rainfall retrieval from a C-Band weather radar in a tropical environment (The Philippines)

    Science.gov (United States)

    Crisologo, I.; Vulpiani, G.; Abon, C. C.; David, C. P. C.; Bronstert, A.; Heistermann, Maik

    2014-11-01

    We evaluated the potential of polarimetric rainfall retrieval methods for the Tagaytay C-Band weather radar in the Philippines. For this purpose, we combined a method for fuzzy echo classification, an approach to extract and reconstruct the differential propagation phase, Φ DP , and a polarimetric self-consistency approach to calibrate horizontal and differential reflectivity. The reconstructed Φ DP was used to estimate path-integrated attenuation and to retrieve the specific differential phase, K DP . All related algorithms were transparently implemented in the Open Source radar processing software wradlib. Rainfall was then estimated from different variables: from re-calibrated reflectivity, from re-calibrated reflectivity that has been corrected for path-integrated attenuation, from the specific differential phase, and from a combination of reflectivity and specific differential phase. As an additional benchmark, rainfall was estimated by interpolating the rainfall observed by rain gauges. We evaluated the rainfall products for daily and hourly accumulations. For this purpose, we used observations of 16 rain gauges from a five-month period in the 2012 wet season. It turned out that the retrieval of rainfall from K DP substantially improved the rainfall estimation at both daily and hourly time scales. The measurement of reflectivity apparently was impaired by severe miscalibration while K DP was immune to such effects. Daily accumulations of rainfall retrieved from K DP showed a very low estimation bias and small random errors. Random scatter was, though, strongly present in hourly accumulations.

  19. Full polarimetric millimetre wave radar for stand-off security screening

    Science.gov (United States)

    Blackhurst, Eddie; Salmon, Neil; Southgate, Matthew

    2017-10-01

    The development and measurements are described of a frequency modulated continuous wave (FMCW) mono-static millimetre wave full polarimetric radar, operating at k-band (18 to 26 GHz). The system has been designed to explore the feasibility of using full polarimetry for the detection of concealed weapons, and person borne improvised explosive devices (PBIED). The philosophy of this scheme is a means to extract the maximum information content from a target which is normally in the single spatial pixel (sometimes sub-pixel) configuration in stand-off (tens of metres) and crowd surveillance scenarios. The radar comprises a vector network analyser (VNA), an orthomode transducer and a conical horn antenna. A calibration strategy is discussed and demonstrated using a variety of known calibration targets with known reflective properties, including a flat metal plate, dihedral reflector, metal sphere, helix and dipole. The orthomode transducer is based on a high performance linear polarizer of the turnstile type with isolation better than - 35dB between orthogonal polarisations. The calibration enables the polarimetric Sinclair scattering matrix to be measured at each frequency for coherent polarimetry, and this can be extended using multiple measurements via the Kennaugh matrix to investigate incoherent full polarimetry.

  20. Handheld SFDI/polarimetric imaging device for objective evaluation of hypertrophic scars (Conference Presentation)

    Science.gov (United States)

    Ramella-Roman, Jessica C.; Montejo, Karla; Sevilla, Nicole; Stoff, Susan; Gonzalez, Mariacarla; Chue-Sang, Joseph

    2017-02-01

    Scars can be debilitating and cause serious functional limitations, significantly reduced physical function and loss of ability to perform normal daily activities. Scar formation is not fully understood and the treatment options have been hampered by the lack of an objective diagnostic tool to assess scars. Presently, assessment of hypertrophic scars has been based on subjective clinician rankings using a four-parameter scale called the Vancouver Scar Scale (VSS) or the Patient Observer Scar Assessment Scale (POSAS) but no objective, standardized tool for quantifying scar severity is available, despite known inadequacies of the subjective scales. We have developed a hand-held multi modal system consisting of a combined Spatial Frequency Domain Imager (SFDI) used for the assessment of tissue molecular components and a polarimeter for structural measurements. The SFDI capability is provided by an Arduino board controlled spectrally and polarimetric diverse Light Emitting Diodes (LED) ring illuminator. For SFDI imagery, the LEDs are combined with sinusoidal patterns. A single pattern snapshot SFDI approach is used to observe and quantify the biological components in the scar tissue including: oxygenated and de oxygenated hemoglobin, water, and melanin. The SFDI system is integrated with a reduced Mueller Matrix polarimetric system, whose illumination is also included in the LED's ring, and providing for the assessment of collagen orientation through Mueller Matrix decomposition. The design of the system and experimental work on phantoms will be presented.

  1. Using WSR-88D Polarimetric Data to Identify Bird-Contaminated Doppler Velocities

    Directory of Open Access Journals (Sweden)

    Yuan Jiang

    2013-01-01

    Full Text Available As an important part of Doppler velocity data quality control for radar data assimilation and other quantitative applications, an automated technique is developed to identify and remove contaminated velocities by birds, especially migrating birds. This technique builds upon the existing hydrometeor classification algorithm (HCA for dual-polarimetric WSR-88D radars developed at the National Severe Storms Laboratory, and it performs two steps. In the first step, the fuzzy-logic method in the HCA is simplified and used to identify biological echoes (mainly from birds and insects. In the second step, another simple fuzzy logic method is developed to detect bird echoes among the biological echoes identified in the first step and thus remove bird-contaminated velocities. The membership functions used by the fuzzy logic method in the second step are extracted from normalized histograms of differential reflectivity and differential phase for birds and insects, respectively, while the normalized histograms are constructed by polarimetric data collected during the 2012 fall migrating season and sorted for bird and insects, respectively. The performance and effectiveness of the technique are demonstrated by real-data examples.

  2. Polarimetric Imaging Of Protoplanetary Disks From The Optical To Sub-Mm

    Science.gov (United States)

    De Boer, Jos; Ménard, F.; Pinte, C.; van der Plas, G.; Snik, F.

    2017-10-01

    To learn how planets form from the smallest building blocks within protoplanetary disks, we first need to know how dust grains grow from micron to mm sizes. Polarimetry across the spectrum has proven to be sensitive to grain properties like dust size distribution and composition and thus can be used to characterize the scattering grains. However, polarization measured with radio interferometric arrays is rarely studied in concert with optical polarimetry. Our team has successfully calibrated the NIR polarimetric imaging mode of VLT/SPHERE, hence upgrading the instrument from a high-contrast imager to a robust tool for quantitative characterization. In this presentation, we will discuss which lessons can be learned by comparing polarimetry in the optical and sub-mm and explore for which science cases both techniques can complement each other. When we combine the polarimetric capabilities of the most advanced optical high-contrast imagers (e.g., Gemini GPI or VLT SPHERE) with that of ALMA we will be able to study the spatial distribution of an extensive range of different grains, which allows us to take an essential step towards a deeper understanding of planet formation.

  3. Algorithm Development for the Optimum Rainfall Estimation Using Polarimetric Variables in Korea

    Directory of Open Access Journals (Sweden)

    Cheol-Hwan You

    2015-01-01

    Full Text Available In this study, to get an optimum rainfall estimation using polarimetric variables observed from Bislsan radar which is the first polarimetric radar in Korea, rainfall cases for 84 hours caused by different conditions, which are Changma front and typhoon, Changma front only, and typhoon only, occurred in 2011, were analyzed. And rainfall algorithms were developed by using long period drop size distributions with six different raindrop axis ratio relations. The combination of the relations between R and Z, ZDR, R and KDP, ZDR, and R and KDP with different rainfall intensity would be an optimum rainfall algorithm if the reference of rainfall would be defined correctly. In the case the reference is not defined adequately, the relation between R and Z, ZDR, KDP, AH and R and Z, KDP, AH can be used as a representative rainfall relation. Particularly if the qualified ZDR is not available, the relation between R and Z, KDP, AH can be used as an optimum rainfall relation in Korea.

  4. Landslide Mapping in Vegetated Areas Using Change Detection Based on Optical and Polarimetric SAR Data

    Directory of Open Access Journals (Sweden)

    Simon Plank

    2016-04-01

    Full Text Available Mapping of landslides, quickly providing information about the extent of the affected area and type and grade of damage, is crucial to enable fast crisis response, i.e., to support rescue and humanitarian operations. Most synthetic aperture radar (SAR data-based landslide detection approaches reported in the literature use change detection techniques, requiring very high resolution (VHR SAR imagery acquired shortly before the landslide event, which is commonly not available. Modern VHR SAR missions, e.g., Radarsat-2, TerraSAR-X, or COSMO-SkyMed, do not systematically cover the entire world, due to limitations in onboard disk space and downlink transmission rates. Here, we present a fast and transferable procedure for mapping of landslides, based on change detection between pre-event optical imagery and the polarimetric entropy derived from post-event VHR polarimetric SAR data. Pre-event information is derived from high resolution optical imagery of Landsat-8 or Sentinel-2, which are freely available and systematically acquired over the entire Earth’s landmass. The landslide mapping is refined by slope information from a digital elevation model generated from bi-static TanDEM-X imagery. The methodology was successfully applied to two landslide events of different characteristics: A rotational slide near Charleston, West Virginia, USA and a mining waste earthflow near Bolshaya Talda, Russia.

  5. Development and Testing of Operational Dual-Polarimetric Radar Based Lightning Initiation Forecast Techniques

    Science.gov (United States)

    Woodard, Crystal; Carey, Lawrence D.; Petersen, Walter A.; Felix, Mariana; Roeder, William P.

    2011-01-01

    Lightning is one of Earth s natural dangers, destructive not only to life but also physical property. According to the National Weather Service, there are on average 58 lightning fatalities each year, with over 300 related injuries (NWS 2010). The ability to forecast lightning is critical to a host of activities ranging from space vehicle launch operations to recreational sporting events. For example a single lightning strike to a Space Shuttle could cause billions of dollars of damage and possible loss of life. While forecasting that provides longer lead times could provide sporting officials with more time to respond to possible threatening weather events, thus saving the lives of player and bystanders. Many researchers have developed and tested different methods and tools of first flash forecasting, however few have done so using dual-polarimetric radar variables and products on an operational basis. The purpose of this study is to improve algorithms for the short-term prediction of lightning initiation through development and testing of operational techniques that rely on parameters observed and diagnosed using C-band dual-polarimetric radar.

  6. Make Sense?

    DEFF Research Database (Denmark)

    Gyrd-Jones, Richard; Törmälä, Minna

    sense of brands is related to who people think they are in their context and this shapes what they enact and how they interpret the brand (Currie & Brown, 2003; Weick, Sutcliffe, & Obstfeld, 2005; Weick, 1993). Our subject of interest in this paper is how stakeholders interpret and ascribe meaning...... to the brand and how these meaning narratives play out over time to create meta-narratives that drive brand meaning co-creation. In this paper we focus on the concept of brand identity since it is at the level of identity that the brand creates meaning for individuals (Kapferer, 2012; Csaba & Bengtsson, 2006).......Purpose: An important part of how we sense a brand is how we make sense of a brand. Sense-making is naturally strongly connected to how we cognize about the brand. But sense-making is concerned with multiple forms of knowledge that arise from our interpretation of the brand-related stimuli...

  7. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... Your Carbs Count Glycemic Index Low-Calorie Sweeteners Sugar and Desserts Fitness Exercise & Type 1 Diabetes Get Started Safely Get And Stay Fit Types ... the following: High blood glucose High levels of sugar in the ... Part of managing your diabetes is checking your blood glucose often. Ask your ...

  8. Hyperglycemia (High Blood Glucose)

    Medline Plus

    Full Text Available ... by Mail Close www.diabetes.org > Living With Diabetes > Treatment and Care > Blood Glucose Testing Share: Print Page ... and-how-tos, . In this section Living With Diabetes Treatment and Care Blood Glucose Testing Checking Your Blood ...

  9. Blood Test: Glucose

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Blood Test: Glucose KidsHealth / For Parents / Blood Test: Glucose What's ... español Análisis de sangre: glucosa What Is a Blood Test? A blood test is when a sample of ...

  10. Decomposition of Polarimetric SAR Images Based on Second- and Third-order Statics Analysis

    Science.gov (United States)

    Kojima, S.; Hensley, S.

    2012-12-01

    There are many papers concerning the research of the decomposition of polerimetric SAR imagery. Most of them are based on second-order statics analysis that Freeman and Durden [1] suggested for the reflection symmetry condition that implies that the co-polarization and cross-polarization correlations are close to zero. Since then a number of improvements and enhancements have been proposed to better understand the underlying backscattering mechanisms present in polarimetric SAR images. For example, Yamaguchi et al. [2] added the helix component into Freeman's model and developed a 4 component scattering model for the non-reflection symmetry condition. In addition, Arii et al. [3] developed an adaptive model-based decomposition method that could estimate both the mean orientation angle and a degree of randomness for the canopy scattering for each pixel in a SAR image without the reflection symmetry condition. This purpose of this research is to develop a new decomposition method based on second- and third-order statics analysis to estimate the surface, dihedral, volume and helix scattering components from polarimetric SAR images without the specific assumptions concerning the model for the volume scattering. In addition, we evaluate this method by using both simulation and real UAVSAR data and compare this method with other methods. We express the volume scattering component using the wire formula and formulate the relationship equation between backscattering echo and each component such as the surface, dihedral, volume and helix via linearization based on second- and third-order statics. In third-order statics, we calculate the correlation of the correlation coefficients for each polerimetric data and get one new relationship equation to estimate each polarization component such as HH, VV and VH for the volume. As a result, the equation for the helix component in this method is the same formula as one in Yamaguchi's method. However, the equation for the volume

  11. Sub-Seasonal Variability of Tropical Rainfall Observed by TRMM and Ground-based Polarimetric Radar

    Science.gov (United States)

    Dolan, Brenda; Rutledge, Steven; Lang, Timothy; Cifelli, Robert; Nesbitt, Stephen

    2010-05-01

    Studies of tropical precipitation characteristics from the TRMM-LBA and NAME field campaigns using ground-based polarimetric S-band data have revealed significant differences in microphysical processes occurring in the various meteorological regimes sampled in those projects. In TRMM-LMA (January-February 1999 in Brazil; a TRMM ground validation experiment), variability is driven by prevailing low-level winds. During periods of low-level easterlies, deeper and more intense convection is observed, while during periods of low-level westerlies, weaker convection embedded in widespread stratiform precipitation is common. In the NAME region (North American Monsoon Experiment, summer 2004 along the west coast of Mexico), strong terrain variability drives differences in precipitation, with larger drops and larger ice mass aloft associated with convection occurring over the coastal plain compared to convection over the higher terrain of the Sierra Madre Occidental, or adjacent coastal waters. Comparisons with the TRMM precipitation radar (PR) indicate that such sub-seasonal variability in these two regions are not well characterized by the TRMM PR reflectivity and rainfall statistics. TRMM PR reflectivity profiles in the LBA region are somewhat lower than S-Pol values, particularly in the more intense easterly regime convection. In NAME, mean reflectivities are even more divergent, with TRMM profiles below those of S-Pol. In both regions, the TRMM PR does not capture rain rates above 80 mm hr-1 despite much higher rain rates estimated from the S-Pol polarimetric data, and rain rates are generally lower for a given reflectivity from TRMM PR compared to S-Pol. These differences between TRMM PR and S-Pol may arise from the inability of Z-R relationships to capture the full variability of microphysical conditions or may highlight problems with TRMM retrievals over land. In addition to the TRMM-LBA and NAME regions, analysis of sub-seasonal precipitation variability and

  12. VizieR Online Data Catalog: Main-belt asteroids polarimetric survey. II. (Gil-Hutton+, 2012)

    Science.gov (United States)

    Gil-Hutton, R.; Canada-Assandri, M.

    2012-01-01

    Results for the objects observed during the polarimetric survey of main-belt asteroids. The observations were carried out during different observing runs between May 2004 and November 2009 at the 2.15m telescope of the CASLEO, San Juan, Argentina, using the Torino and CASPROF polarimeters. (3 data files).

  13. Use of Radarsat-2 polarimetric SAR images for fuel moisture mapping in the Kruger National Park, South Africa

    CSIR Research Space (South Africa)

    Kong, M

    2015-08-01

    Full Text Available Fully polarimetric Radarsat-2 imagery from wet and dry conditions over the South African Lowveld is compared to assess its value for fuel moisture mapping. Imagery was acquired at two different dates, in May (end of summer, wet) and in August (mid...

  14. Basics and first experiments demonstrating isolation improvements in the agile polarimetric FM-CW radar – PARSAX

    NARCIS (Netherlands)

    Krasnov, O.A.; Babur, G.P.; Wang, Z.; Ligthart, L.P.; Van der Zwan, F.

    2010-01-01

    The article describes the IRCTR PARSAX radar system, the S-band high-resolution Doppler polarimetric frequency modulated continuous wave (FM-CW) radar with dual-orthogonal sounding signals, which has the possibility to measure all elements of the radar target polarization scattering matrix

  15. High-resolution polarimetric X-band weather radar observations at the Cabauw Experimental Site for Atmospheric Research

    NARCIS (Netherlands)

    Otto, T.; Russchenberg, H.W.J.

    2013-01-01

    In 2007, the horizontally scanning polarimetric X-band radar IDRA (IRCTR Drizzle Radar) was installed on top of the 213 m high mast at the Dutch meteorological observatory Cabauw Experimental Site for Atmospheric Research (CESAR) at Netherlands. This radar complements a large variety of measurement

  16. Clustering of Multi-Temporal Fully Polarimetric L-Band SAR Data for Agricultural Land Cover Mapping

    Science.gov (United States)

    Tamiminia, H.; Homayouni, S.; Safari, A.

    2015-12-01

    Recently, the unique capabilities of Polarimetric Synthetic Aperture Radar (PolSAR) sensors make them an important and efficient tool for natural resources and environmental applications, such as land cover and crop classification. The aim of this paper is to classify multi-temporal full polarimetric SAR data using kernel-based fuzzy C-means clustering method, over an agricultural region. This method starts with transforming input data into the higher dimensional space using kernel functions and then clustering them in the feature space. Feature space, due to its inherent properties, has the ability to take in account the nonlinear and complex nature of polarimetric data. Several SAR polarimetric features extracted using target decomposition algorithms. Features from Cloude-Pottier, Freeman-Durden and Yamaguchi algorithms used as inputs for the clustering. This method was applied to multi-temporal UAVSAR L-band images acquired over an agricultural area near Winnipeg, Canada, during June and July in 2012. The results demonstrate the efficiency of this approach with respect to the classical methods. In addition, using multi-temporal data in the clustering process helped to investigate the phenological cycle of plants and significantly improved the performance of agricultural land cover mapping.

  17. An omnibus likelihood test statistic and its factorization for change detection in time series of polarimetric SAR data

    DEFF Research Database (Denmark)

    Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning

    2016-01-01

    Based on an omnibus likelihood ratio test statistic for the equality of several variance-covariance matrices following the complex Wishart distribution with an associated p-value and a factorization of this test statistic, change analysis in a short sequence of multilook, polarimetric SAR data...

  18. Comparison of vehicle-mounted forward-looking polarimetric infrared and downward-looking infrared sensors for landmine detection

    NARCIS (Netherlands)

    Cremer, F.; Schavemaker, J.G.M.; Jong, W. de; Schutte, K.

    2003-01-01

    This paper gives a comparison of two vehicle-mounted infrared systems for landmine detection. The first system is a down-ward looking standard infrared camera using processing methods developed within the EU project LOTUS. The second system is using a forward-looking polarimetric infrared camera.

  19. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    International Nuclear Information System (INIS)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-01-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  20. MAIA pathfinder: Imaging Polarimetric Assessment and Characterization of Tropospheric Particulate Matter (ImPACT-PM) field campaign

    Science.gov (United States)

    Kalashnikova, O. V.; Seidel, F. C.; Xu, F.; Garay, M. J.; Wu, L.; Bruegge, C. J.; van Harten, G.; Val, S.; Diner, D. J.; Seinfeld, J.; Bates, K. H.; Cappa, C. D.; Bradley, C. L.; Kupinski, M.; Clements, C. B.; Camacho, C.; Yorks, J. E.

    2016-12-01

    The Multi-Angle Imager for Aerosols (MAIA) instrument, which was recently selected under NASA's third Earth Venture Instrument call, will improve aerosol particle type sensitivity through the atmospheric column as well as at the surface through the use of multiangular, multispectral, and polarimetric observations. MAIA will provide new information that enables estimates of speciated (size- and particle type classifications) surface particulate matter (PM) from space over major cities around the globe, and enable improved associations between particulate air pollution and human health. As a pathfinder to MAIA, the ImPACT-PM field campaign was a joint JPL/Caltech effort to combine measurements from MISR and AirMSPI with in situ airborne measurements and a chemical transport model to validate remote sensing retrievals of different types of airborne particulate matter. We will present highlights of the successfully completed ImPACT-PM field campaign which took place in the California Central Valley on July 5-8, 2016. We had two NASA ER-2/ CIRPAS Twin Otter collocated flights coincident with Terra/MISR overpasses on Tuesday and Thursday July 5 and 7; and two ER-2/Twin Otter collocations over local fires on Friday, July 8th. The AirMSPI, AirSPEX, and CPL instruments were integrated on the ER-2, and Caltech aerosol/cloud in-situ instruments were integrated on the CIRPAS Twin Otter aircraft in addition to the normal Twin Otter payload. We also deployed the JPL/University of Arizona GroundMSPI instrument and a ground-based lidar from San José State University at the Fresno California Air Resources Board super-site. While the overall aerosol and PM levels were low at this time, we were able to see a gradient of pollution in specially processed MISR high-resolution 4.4 km resolution aerosol data on both days. We will present initial results of AirMSPI WRF-Chem-constrained retrievals in comparison with EPA Speciation Trends Network stations in Fresno and Bakersfield, and with

  1. Resolving futile glucose cycling and glycogenolytic contributions to plasma glucose levels following a glucose load

    NARCIS (Netherlands)

    Nunes, P.M.; Jarak, I.; Heerschap, A.; Jones, J.G.

    2014-01-01

    PURPOSE: After a glucose load, futile glucose/glucose-6-phosphate (G6P) cycling (FGC) generates [2-(2) H]glucose from (2) H2 O thereby mimicking a paradoxical glycogenolytic contribution to plasma glucose levels. Contributions of load and G6P derived from gluconeogenesis, FGC, and glycogenolysis to

  2. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    Science.gov (United States)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-08-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  3. On the Use of Generalized Volume Scattering Models for the Improvement of General Polarimetric Model-Based Decomposition

    Directory of Open Access Journals (Sweden)

    Qinghua Xie

    2017-01-01

    Full Text Available Recently, a general polarimetric model-based decomposition framework was proposed by Chen et al., which addresses several well-known limitations in previous decomposition methods and implements a simultaneous full-parameter inversion by using complete polarimetric information. However, it only employs four typical models to characterize the volume scattering component, which limits the parameter inversion performance. To overcome this issue, this paper presents two general polarimetric model-based decomposition methods by incorporating the generalized volume scattering model (GVSM or simplified adaptive volume scattering model, (SAVSM proposed by Antropov et al. and Huang et al., respectively, into the general decomposition framework proposed by Chen et al. By doing so, the final volume coherency matrix structure is selected from a wide range of volume scattering models within a continuous interval according to the data itself without adding unknowns. Moreover, the new approaches rely on one nonlinear optimization stage instead of four as in the previous method proposed by Chen et al. In addition, the parameter inversion procedure adopts the modified algorithm proposed by Xie et al. which leads to higher accuracy and more physically reliable output parameters. A number of Monte Carlo simulations of polarimetric synthetic aperture radar (PolSAR data are carried out and show that the proposed method with GVSM yields an overall improvement in the final accuracy of estimated parameters and outperforms both the version using SAVSM and the original approach. In addition, C-band Radarsat-2 and L-band AIRSAR fully polarimetric images over the San Francisco region are also used for testing purposes. A detailed comparison and analysis of decomposition results over different land-cover types are conducted. According to this study, the use of general decomposition models leads to a more accurate quantitative retrieval of target parameters. However, there

  4. Polarimetric survey of main-belt asteroids. II. Results for 58 B- and C-type objects

    Science.gov (United States)

    Gil-Hutton, R.; Cañada-Assandri, M.

    2012-03-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico el Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data on a sample of more than 170 asteroids were obtained. In this paper the results for 58 B- and C-type objects are presented, most of them polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for these taxonomic classes. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Tables 1 and 2 are available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A115

  5. Polarimetric survey of main-belt asteroids. I. Results for fifty seven S-, L-, and K-type objects

    Science.gov (United States)

    Gil-Hutton, R.; Cañada-Assandri, M.

    2011-05-01

    Aims: We present the first results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties, similar to those shown by the asteroid (234) Barbara. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15 m telescope. The Torino polarimeter is an instrument that allows the simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data on a sample of more than 170 asteroids were obtained. In this paper the results of 57 S-, L-, and K-type objects are presented, most of them are being polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for these taxonomic classes. Furthermore, we also find two candidates, (397) Vienna and (458) Hercynia, that could have a phase-polarization curve with a large inversion angle. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?j/A+A/529/A86

  6. Self-monitoring of tear glucose: the development of a tear based glucose sensor as an alternative to self-monitoring of blood glucose.

    Science.gov (United States)

    La Belle, Jeffrey T; Adams, Anngela; Lin, Chi-En; Engelschall, Erica; Pratt, Breanna; Cook, Curtiss B

    2016-07-28

    Tear glucose sensing for diabetes management has long been sought as an alternative to more invasive self-monitoring of blood glucose (SMBG). However, tear glucose sensors were known to have limitations, including correlation issues with blood glucose due to low sample volume, low concentration of glucose in the tear fluid, and evaporation of the tear sample. An engineering design approach to solve these problems led to the development of an integrated device capable of collecting the tear sample from the ocular surface with little to no stress on the eye, with an extremely low limit of detection, broad dynamic range, and rapid detection and analysis of sample. Here we present the development of a prototypical self-monitoring of tear glucose (SMTG) sensor, summarizing bench studies on the enzymes and their specificity, the development of the fluid capture device and its manufacture and performance and results of system testing in an animal study where safety, lag time and tear glucose to blood glucose correlation were assessed.

  7. Implanted electroenzymatic glucose sensors.

    Science.gov (United States)

    Clark, L C; Duggan, C A

    1982-01-01

    The advent of electrochemical sensors for intermittent sampling of blood gases and hydrogen ions in the clinic, intensive care, and surgical units has revolutionized diagnostic and critical care medical technics. The use of electrochemical sensors for continuous transcutaneous monitoring of blood gases is further enhancing the medical surveillance of patients. The more recent introduction of glucose and other electroenzymatic sensors has stimulated broad research in the development of metabolic monitoring. For the present research, the glucose sensor widely used for the rapid specific micro-analysis of whole blood and plasma is explored for possible use as an in vivo intravascular or tissue-implanted sensor. This sensor is based on the polarographic measurement of hydrogen peroxide generated by glucose oxidase (EC 1.1.3.4) held between two membranes. The first membrane allows the diffusion of glucose, ions, and many other small molecules, while the second membrane allows the diffusion of the glucose-generated hydrogen peroxide to the platinum surface, but excludes ascorbic acid, bilirubin, and uric acid. Such sensors respond rapidly and specifically when acutely implanted subcutaneously in cats and dogs. They function well as glucose-sensor-tipped venous catheters. One sensor was repeatedly used for in vitro polarograms, subcutaneous and blood glucose monitoring, over a period of ten months, with storage in the cold between uses, with the complete retention of its response characteristics.

  8. Astrocytes in the nucleus of the solitary tract are activated by low glucose or glucoprivation: evidence for glial involvement in glucose homeostasis.

    Directory of Open Access Journals (Sweden)

    David Harry McDougal

    2013-12-01

    Full Text Available Glucose homeostasis is maintained through interplay between central and peripheral control mechanisms which are aimed at storing excess glucose following meals and mobilizing these same stores during periods of fasting. The nucleus of the solitary tract (NST in the dorsal medulla has long been associated with the central detection of glucose availability and the control of glucose homeostasis. Recent evidence has emerged which supports the involvement of astrocytes in glucose homeostasis. The aim of the present study was to investigate whether NST-astrocytes respond to physiologically relevant decreases in glucose availability, in vitro, as well as to the presence of the glucoprivic compound 2-deoxy-D-Glucose. This report demonstrates that some NST-astrocytes are capable of responding to low glucose or glucoprivation by increasing cytoplasmic calcium; a change that reverses with restoration of normal glucose availability. While some NST-neurons also demonstrate an increase in calcium signaling during low glucose availability, this effect is smaller and somewhat delayed compared to those observed in adjacent astrocytes. TTX did not abolish these hypoglycemia mediated responses of astrocytes, suggesting that NST-astrocytes may be directly sensing low glucose levels as opposed to responding to neuronal detection of hypoglycemia. Thus, chemodetection of low glucose by NST-astrocytes may play an important role in the autonomic regulation of glucose homeostasis.

  9. Blood Glucose Determination

    DEFF Research Database (Denmark)

    Lippi, Giuseppe; Nybo, Mads; Cadamuro, Janne

    2018-01-01

    The measurement of fasting plasma glucose may be biased by a time-dependent decrease of glucose in blood tubes, mainly attributable to blood cell metabolism when glycolysis is not rapidly inhibited or blood cells cannot be rapidly separated from plasma. Although glycolysis inhibitors such as sodium...... fluoride (NaF) in combination with potassium oxalate (KOx) are currently used for overcoming this drawback, their efficacy for stabilizing blood glucose is seemingly limited, and probably lower than that of newer additives such as the citrate buffer. Therefore, we performed a critical analysis...

  10. A New Polarimetric Study of Cygnus A Using JVLA from 2-18GHz

    Science.gov (United States)

    Lerato Sebokolodi, Makhuduga; Perley, Rick; Carilli, Chris; Smirnov, Oleg M.; Makhathini, Sphesihle

    2018-01-01

    Polarimetric studies of Cygnus A [5, 1, 2, 3] have shown that this radio galaxy has unusually large rotation measures ranging from -4000 to +3000 rad m -2 for the eastern lobe (E-lobe) and -2000 to +1300 rad m -2 for western lobe(W-lobe). A challenge since then has been to identify the medium(s) responsible for these high Faraday rotations (FR). Although a majority of the FR must arise from the surrounding cluster gas, an unknown portion may arise either in the sheath or within the lobes. In these cases, some depolarization must result, along with a non λ 2 rotation of the plane of polarization. Detecting such a depolarization will enable an estimate of the internal (and/or sheath) thermal gas density. [1] found significant depolarization associated with the inner regions of the E-lobe and no depolarization associated with the W-lobe. This depolarization could be either internal to the source (Faraday depolarization) or due to unresolved small-scale fluctuations in the foreground screen (beam depolarization) [1]. The former is expected to impose significant deviations in the λ2 -law, none of which have been found to date, nor could have been found due to the limited number of frequencies employed in these studies.Since 2015, new JVLA polarimetric observations of Cygnus A have been taken, in all four configurations, covering the frequency range from 2 to 18GHz. These new data provide thousands of frequency channels at high resolution and sensitivity – opening a new opportunity to study in great detail the physics of the jets, lobes and the magnetic field of the X-ray cluster medium and lobes. Our objective is to analyze these new polarimetric data with the expectation of extending the previous work and more importantly, to investigate the possibility of any significantdeviations from the λ2-law. Initial analysis shows significant deviations from λ2 -law associated with the W-lobe. We will present these results in detail, and also the results from RM

  11. Polarimetric mountain based radio-occultation for rain detection: The ROHP-PAZ ground campaign

    Science.gov (United States)

    Padulles, Ramon; Cardellach, Estel; Tomas, Sergio; de la Torre, Manuel; Turk, Joe

    2014-05-01

    The Radio Occultation and Heavy Precipitation experiment aboard the PAZ Low Earth Orbiter (ROHP-PAZ) is a mission of opportunity: The Spanish Ministry of Science and Innovation (MICINN) approved in 2009 a proposal to include a polarimetric Global Navigation Satellite System (GNSS) Radio-Occultation (RO) payload on board of the Spanish Earth Observation satellite PAZ. This will be a new technique that has never been tested before, that aims to improve the knowledge of precipitation through simultaneous thermodynamic and vertical rain profiles. Prior to the launch of the satellite, expected for 2014, a ground experimental campaign is being conducted with the goal of starting the process of identifying and understanding all the factors that might affect the polarimetric RO observables. The campaign is being carried out at the top of Puig Sesolles, a 1667m peak in the Natural Park of Montseny (41º46'24 N, 2º26'17 E), 50 km N-NE from Barcelona, with clear views over the horizon to the South (East to West) direction, an area in which intense precipitation events tend to occur a few times per year. The campaign uses a ICE-CSIC/IEEC's GOLD-RTR open-loop receiver initially designed for collecting GNSS signals reflected off the sea surface. The receiver has been adjusted to track occulting GNSS radio-links. A double polarization (H and V) GNSS antenna has been designed and manufactured by the Polytechnic University of Barcelona (UPC) team for this particular ground-based experiment. The antenna is a phase-array made of 7 elements, each of them being a square patch built using a Rogers 4003 substrate, and symmetrically fed by four probes. It provides a pattern of 12.9 dB peak gain, 45 degrees half-power beam-width, and <-35 dB cross-polar isolation at the peak (better than -30 dB in the main lobe). The preliminary results show that not only precipitation, but also other factors are affecting the GNSS signal, wich means that the polarimetric signal is richer than expected

  12. Polarimetric Intensity Parameterization of Radar and Other Remote Sensing Sources for Advanced Exploitation and Data Fusion: Theory

    Science.gov (United States)

    2008-10-01

    En se basant sur ce qui précède, on étudie les caractéristiques communes, l’interfonctionnement et la fusion de divers produits de capteurs ...polarimétriques dans diverses régions du spectre, p. ex. le radar classique ou le radar à synthèse d’ouverture et des capteurs électro-optiques, et on formule...électromagnétiques rétrodiffusées fournit davantage de données pour la reconnaissance des objectifs que les capteurs de télédétection monovoie classiques. Nous voulons

  13. Mapping Mangroves Extents on the Red Sea Coastline in Egypt using Polarimetric SAR and High Resolution Optical Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    Ayman Abdel-Hamid

    2018-02-01

    Full Text Available Mangroves ecosystems dominate the coastal wetlands of tropical and subtropical regions throughout the world. They are among the most productive forest ecosystems. They provide various ecological and economic ecosystem services. Despite of their economic and ecological importance, mangroves experience high yearly loss rates. There is a growing demand for mapping and assessing changes in mangroves extents especially in the context of climate change, land use change, and related threats to coastal ecosystems. The main objective of this study is to develop an approach for mapping of mangroves extents on the Red Sea coastline in Egypt, through the integration of both L-band SAR data of ALOS/PALSAR, and high resolution optical data of RapidEye. This was achieved via using object-based image analysis method, through applying different machine learning algorithms, and evaluating various features such as spectral properties, texture features, and SAR derived parameters for discrimination of mangroves ecosystem classes. Three non-parametric machine learning algorithms were tested for mangroves mapping; random forest (RF, support vector machine (SVM, and classification and regression trees (CART. As an input for the classifiers, we tested various features including vegetation indices (VIs and texture analysis using the gray-level co-occurrence matrix (GLCM. The object-based analysis method allowed clearly discriminating the different land cover classes within mangroves ecosystem. The highest overall accuracy (92.15% was achieved by the integrated SAR and optical data. Among all classifiers tested, RF performed better than other classifiers. Using L-band SAR data integrated with high resolution optical data was beneficial for mapping and characterization of mangroves growing in small patches. The maps produced represents an important updated reference suitable for developing a regional action plan for conservation and management of mangroves resources along the Red Sea coastline.

  14. Polarimetric and Interferometric Synthetic Aperture Radar (Pol-InSAR); a new way to quantify three-dimensional structure of Earth and planetary surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This study will employ a three phased approach: SAR image formation and calibration. DBSAR polarimetric and interferometric data analysis. PolInSAR algorithm...

  15. GHRSST Level 3U Global Subskin Sea Surface Temperature from the WindSat Polarimetric Radiometer on the Coriolis satellite (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The WindSat Polarimetric Radiometer, launched on January 6, 2003 aboard the Department of Defense Coriolis satellite, was designed to measure the ocean surface wind...

  16. Hyperglycemia (High Blood Glucose)

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  7. Application of radar polarimetry techniques for retrieval snow and rain characteristics in remote sensing

    Directory of Open Access Journals (Sweden)

    M. Darvishi

    2013-09-01

    Full Text Available The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MODIS sensor for Norway, Finnish with AVHRR sensor for Finland and NASA with MODIS sensor for global maps. Monitoring snow cover at different parts of spectral electromagnetic is detectable (visible, near and thermal infrared, passive and active microwave. Recently, specific capabilities of active microwave remote sensing such as snow extent map, snow depth, snow water equivalent (SWE, snow state (wet/dry and discrimination between rain and snow region were given a strong impetus for using this technology in snow monitoring, hydrology, climatology, avalanche research and etc. This paper evaluates the potentials and feasibility of polarimetric ground microwave measurements of snow in active remote sensing field. We will consider the behavior co- and cross-polarized backscattering coefficients of snowpack response with polarimetric scatterometer in Ku and L band at the different incident angles. Then we will show how to retrieve snow cover depth, snow permittivity and density parameters at the local scale with ground-based SAR (GB-SAR. Finally, for the sake of remarkable significant the transition region between rain and snow; the variables role of horizontal reflectivity (ZHH and differential reflectivity (ZDR in delineation boundary between snow and rain and some others important variables at polarimetric weather radar are presented.

  8. Application of radar polarimetry techniques for retrieval snow and rain characteristics in remote sensing

    Science.gov (United States)

    Darvishi, M.; Ahmadi, Gh. R.

    2013-09-01

    The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MODIS sensor for Norway, Finnish with AVHRR sensor for Finland and NASA with MODIS sensor for global maps. Monitoring snow cover at different parts of spectral electromagnetic is detectable (visible, near and thermal infrared, passive and active microwave). Recently, specific capabilities of active microwave remote sensing such as snow extent map, snow depth, snow water equivalent (SWE), snow state (wet/dry) and discrimination between rain and snow region were given a strong impetus for using this technology in snow monitoring, hydrology, climatology, avalanche research and etc. This paper evaluates the potentials and feasibility of polarimetric ground microwave measurements of snow in active remote sensing field. We will consider the behavior co- and cross-polarized backscattering coefficients of snowpack response with polarimetric scatterometer in Ku and L band at the different incident angles. Then we will show how to retrieve snow cover depth, snow permittivity and density parameters at the local scale with ground-based SAR (GB-SAR). Finally, for the sake of remarkable significant the transition region between rain and snow; the variables role of horizontal reflectivity (ZHH) and differential reflectivity (ZDR) in delineation boundary between snow and rain and some others important variables at polarimetric weather radar are presented.

  9. An ancestral role for the mitochondrial pyruvate carrier in glucose-stimulated insulin secretion

    Directory of Open Access Journals (Sweden)

    Kyle S. McCommis

    2016-08-01

    Conclusions: Altogether, these studies suggest that the MPC plays an important and ancestral role in insulin-secreting cells in mediating glucose sensing, regulating insulin secretion, and controlling systemic glycemia.

  10. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    Science.gov (United States)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; hide

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  11. Modified polarimetric bidirectional reflectance distribution function with diffuse scattering: surface parameter estimation

    Science.gov (United States)

    Zhan, Hanyu; Voelz, David G.

    2016-12-01

    The polarimetric bidirectional reflectance distribution function (pBRDF) describes the relationships between incident and scattered Stokes parameters, but the familiar surface-only microfacet pBRDF cannot capture diffuse scattering contributions and depolarization phenomena. We propose a modified pBRDF model with a diffuse scattering component developed from the Kubelka-Munk and Le Hors et al. theories, and apply it in the development of a method to jointly estimate refractive index, slope variance, and diffuse scattering parameters from a series of Stokes parameter measurements of a surface. An application of the model and estimation approach to experimental data published by Priest and Meier shows improved correspondence with measurements of normalized Mueller matrix elements. By converting the Stokes/Mueller calculus formulation of the model to a degree of polarization (DOP) description, the estimation results of the parameters from measured DOP values are found to be consistent with a previous DOP model and results.

  12. On the calibration of the polarimetric slope - albedo relation for asteroids: Work in progress

    Directory of Open Access Journals (Sweden)

    A. Cellino

    2011-09-01

    Full Text Available Asteroid polarimetry is known to be an excellent tool to derive information on the geometric albedo of these objects. This is made possible by the existence of a relation between the albedo and the morphology of the curve which describes the variation of the degree of linear polarization of asteroid light as a function of the illumination conditions. A major problem is that the calibration of the commonly accepted form of the polarization - albedo relation includes numerical coefficients which are affected by fairly high uncertainties. Following some recommendations issued by IAU Commission 15, we are trying to improve the albedo - polarization relation by taking advantage of new polarimetric data obtained in dedicated observation campaigns. We present here some very preliminary results.

  13. PRELIMINARY RESULTS OF ESTIMATING SOIL MOISTURE OVER BARE SOIL USING FULL-POLARIMETRIC ALOS-2 DATA

    Directory of Open Access Journals (Sweden)

    A. Sekertekin

    2016-10-01

    Full Text Available Synthetic Aperture Radar (SAR imaging system is one of the most effective way for Earth observation. The aim of this study is to present the preliminary results about estimating soil moisture using L-band Synthetic Aperture Radar (SAR data. Full-polarimetric (HH, HV, VV, VH ALOS-2 data, acquired on 22.04.2016 with the incidence angle of 30.4o, were used in the study. Simultaneously with the SAR acquisition, in-situ soil moisture samples over bare agricultural lands were collected and evaluated using gravimetric method. Backscattering coefficients for all polarizations were obtained and linear regression analysis was carried out with in situ moisture measurements. The best correlation coefficient was observed with VV polarization. Cross-polarized backscattering coefficients were not so sensitive to soil moisture content. In the study, it was observed that soil moisture maps can be retrieved with the accuracy about 14% (RMSE.

  14. Bilateral bad pixel and Stokes image reconstruction for microgrid polarimetric imagers

    Science.gov (United States)

    LeMaster, Daniel A.; Ratliff, Bradley M.

    2015-09-01

    Uncorrected or poorly corrected bad pixels reduce the effectiveness of polarimetric clutter suppression. In conventional microgrid processing, bad pixel correction is accomplished as a separate step from Stokes image reconstruction. Here, these two steps are combined to speed processing and provide better estimates of the entire image, including missing samples. A variation on the bilateral filter enables both edge preservation in the Stokes imagery and bad pixel suppression. Understanding the newly presented filter requires two key insights. First, the adaptive nature of the bilateral filter is extended to correct for bad pixels by simply incorporating a bad pixel mask. Second, the bilateral filter for Stokes estimation is the sum of the normalized bilateral filters for estimating each analyzer channel individually. This paper describes the new approach and compares it to our legacy method using simulated imagery.

  15. Space-based detection of space debris by photometric and polarimetric characteristics

    Science.gov (United States)

    Pang, Shuxia; Wang, Hu; Lu, Xiaoyun; Shen, Yang; Pan, Yue

    2017-10-01

    The number of space debris has been increasing dramatically in the last few years, and is expected to increase as much in the future. As the orbital debris population grows, the risk of collision between debris and other orbital objects also grows. Therefore, space debris detection is a particularly important task for space environment security, and then supports for space debris modeling, protection and mitigation. This paper aims to review space debris detection systematically and completely. Firstly, the research status of space debris detection at home and abroad is presented. Then, three kinds of optical observation methods of space debris are summarized. Finally, we propose a space-based detection scheme for space debris by photometric and polarimetric characteristics.

  16. Synergy of optical and polarimetric microwave data for forest resource assessment

    International Nuclear Information System (INIS)

    Miguel-Ayanz, J.S.

    1997-01-01

    Data acquired during the Mac-Europe 91 campaign over the Black Forest ( Germany) are used to study the synergy of optical imaging spectrometer data ( AVIRIS) and polarimetric microwave data ( AIRSAR) for forest resource assessment. Original and new derived bands from AIRSAR and AVIRIS data are used to predict age and biomass. The best predictors ( bands) are selected through a multivariate stepwise regression analysis of each of the datasets separately. Then the joint AIRSAR-AVIRIS dataset is analysed. This study shows how the synergistic use of AIRSAR and AVIRIS data improves significantly the predictions obtained from the individual datasets for both age and biomass over the test site. In the analysis of AVIRIS data a new approach for processing large datasets as those provided by imaging spectrometers is presented, so that maximum likelihood classification of these datasets becomes feasible. (author)

  17. Spectro-polarimetric study of the early evolutionary phases of the most massive galaxies

    International Nuclear Information System (INIS)

    Vernet, Joel

    2001-01-01

    This research thesis addresses the study of the early phases of evolution of the most massive galaxies (giant elliptic), a fundamental process which is a matter of study for various reasons exposed by the author in his introduction. While presented results are based on spectro-polarimetric observations, the author first presents specific instruments and methods used by spectropolarimetry which provides access to variations of all vectorial properties of light, without loss of information. Then, he reports the study of a near powerful radio-galaxy, Cygnus A, the study of nine radio-galaxies with a high redshift, and the study of a far ultra-luminous infrared galaxy (SMM J02399-0136). Results are then discussed and perspectives of research are proposed. Appendices present the theoretical study of the contribution of massive stars to the diffuse extragalactic ionizing background, and observations made on a near radio-galaxy (NGC 6251)

  18. Semi-supervised Learning for Classification of Polarimetric SAR Images Based on SVM-Wishart

    Directory of Open Access Journals (Sweden)

    Hua Wen-qiang

    2015-02-01

    Full Text Available In this study, we propose a new semi-supervised classification method for Polarimetric SAR (PolSAR images, aiming at handling the issue that the number of train set is small. First, considering the scattering characters of PolSAR data, this method extracts multiple scattering features using target decomposition approach. Then, a semi-supervised learning model is established based on a co-training framework and Support Vector Machine (SVM. Both labeled and unlabeled data are utilized in this model to obtain high classification accuracy. Third, a recovery scheme based on the Wishart classifier is proposed to improve the classification performance. From the experiments conducted in this study, it is evident that the proposed method performs more effectively compared with other traditional methods when the number of train set is small.

  19. Link between interplanetary & cometary dust: Polarimetric observations and space studies with Rosetta & Eye-Sat

    Science.gov (United States)

    Levasseur-Regourd, Anny-Chantal; Gaboriaud, Alain; Buil, Christian; Ressouche, Antoine; Lasue, J.; Palun, Adrien; Apper, Fabien; Elmaleh, Marc

    Intensity and linear polarization observations of the solar light scattered by interplanetary dust, the so-called zodiacal light, provide information on properties of the dust particles, such as their spatial density, local changes, morphology and albedo. Earth-based polarimetric observations, with a resolution of 5° or more, have been used to derive the polarization phase curve of interplanetary dust particles and to establish that the polarization at 90° phase angle increases with increasing solar distance, at least up to 1.5 au in the ecliptic, while the albedo decreases [1, 2]. Analysis of such studies will be revisited. Numerical simulations of the polarimetric behavior of interplanetary dust particles strongly suggest that, in the inner solar system, interplanetary dust particles consist of absorbing (e.g., organic compounds) and less absorbing (e.g., silicates) materials, that radial changes originate in a decrease of organics with decreasing solar distance (probably due to alteration processes), and that a significant fraction of the interplanetary dust is of cometary origin, in agreement with dynamical studies [3, 4]. The polarimetric behaviors of interplanetary dust and cometary dust particles seem to present striking similarities. The properties of cometary dust particles, as derived from remote polarimetric observations of comets including 67P/Churyumov-Gerasimenko, the target of the Rosetta rendezvous mission, at various wavelengths, will be summarized [5, 6]. The ground truth expected from Rosetta dust experiments, i.e., MIDAS, COSIMA, GIADA, about dust particles’ morphology, composition, and evolution (with distance to the nucleus before Philae release and with distance to the Sun before and after perihelion passage) over the year and a half of nominal mission, will be discussed. Finally, the Eye-Sat nanosatellite will be presented. This triple cubesat, developed by students from engineering schools working as interns at CNES, is to be launched

  20. ESA'S POLarimetric Airborne Radar Ice Sounder (POLARIS): design and first results

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kristensen, Steen Savstrup; Krozer, Viktor

    2010-01-01

    -of-concept campaign was conducted in Greenland. This study outlines the design and implementation of the system, and based on first results it is concluded that in the central dry snow zone of Greenland, POLARIS can resolve shallow and deep internal ice layers, penetrate the thickest ice encountered and detect......The Technical University of Denmark has developed and tested a P-band ice sounding radar for European Space Agency (ESA). With the recent by the International Telecommunication Union (ITU) allocation of a radar band at 435 MHz, increased interest in space-based sounding of the Earth s ice caps has...... been encountered. ESA s POLarimetric Airborne Radar Ice Sounder (POLARIS) is intended to provide a better understanding of P-band scattering and propagation through ice sheets and to verify novel surface clutter suppression techniques in preparation for a potential space-based ice sounding mission...

  1. Glucose availability enhances lipopolysaccharide production and immunogenicity in the opportunistic pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Rossi, Elio; Longo, Francesca; Barbagallo, Marialuisa; Peano, Clelia; Consolandi, Clarissa; Pietrelli, Alessandro; Jaillon, Sebastian; Garlanda, Cecilia; Landini, Paolo

    2016-01-01

    Acinetobacter baumannii can cause sepsis with high mortality rates. We investigated whether glucose sensing might play a role in A. baumannii pathogenesis. We carried out transcriptome analysis and extracellular polysaccharide determination in an A. baumannii clinical isolate grown on complex medium with or without glucose supplementation, and assessed its ability to induce production of inflammatory cytokines in human macrophages. Growth in glucose-supplemented medium strongly enhanced A. baumannii sugar anabolism, resulting in increasing lipopolysaccharide biosynthesis. In addition, glucose induced active shedding of lipopolysaccharide, in turn triggering a strong induction of inflammatory cytokines in human macrophages. Finally, hemolytic activity was strongly enhanced by growth in glucose-supplemented medium. We propose that sensing of exogenous glucose might trigger A. baumannii pathogenesis during sepsis.

  2. Oil detection in a coastal marsh with polarimetric Synthetic Aperture Radar (SAR)

    Science.gov (United States)

    Ramsey, Elijah W.; Rangoonwala, Amina; Suzuoki, Yukihiro; Jones, Cathleen E.

    2011-01-01

    The National Aeronautics and Space Administration's airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR) sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD) and Cloude-Pottier (CP) decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  3. Oil Detection in a Coastal Marsh with Polarimetric Synthetic Aperture Radar (SAR

    Directory of Open Access Journals (Sweden)

    Cathleen E. Jones

    2011-12-01

    Full Text Available The National Aeronautics and Space Administration’s airborne Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR was deployed in June 2010 in response to the Deepwater Horizon oil spill in the Gulf of Mexico. UAVSAR is a fully polarimetric L-band Synthetic Aperture Radar (SAR sensor for obtaining data at high spatial resolutions. Starting a month prior to the UAVSAR collections, visual observations confirmed oil impacts along shorelines within northeastern Barataria Bay waters in eastern coastal Louisiana. UAVSAR data along several flight lines over Barataria Bay were collected on 23 June 2010, including the repeat flight line for which data were collected in June 2009. Our analysis of calibrated single-look complex data for these flight lines shows that structural damage of shoreline marsh accompanied by oil occurrence manifested as anomalous features not evident in pre-spill data. Freeman-Durden (FD and Cloude-Pottier (CP decompositions of the polarimetric data and Wishart classifications seeded with the FD and CP classes also highlighted these nearshore features as a change in dominant scattering mechanism. All decompositions and classifications also identify a class of interior marshes that reproduce the spatially extensive changes in backscatter indicated by the pre- and post-spill comparison of multi-polarization radar backscatter data. FD and CP decompositions reveal that those changes indicate a transform of dominant scatter from primarily surface or volumetric to double or even bounce. Given supportive evidence that oil-polluted waters penetrated into the interior marshes, it is reasonable that these backscatter changes correspond with oil exposure; however, multiple factors prevent unambiguous determination of whether UAVSAR detected oil in interior marshes.

  4. QuadCam - A Quadruple Polarimetric Camera for Space Situational Awareness

    Science.gov (United States)

    Skuljan, J.

    A specialised quadruple polarimetric camera for space situational awareness, QuadCam, has been built at the Defence Technology Agency (DTA), New Zealand, as part of collaboration with the Defence Science and Technology Laboratory (Dstl), United Kingdom. The design was based on a similar system originally developed at Dstl, with some significant modifications for improved performance. The system is made up of four identical CCD cameras looking in the same direction, but in a different plane of polarisation at 0, 45, 90 and 135 degrees with respect to the reference plane. A standard set of Stokes parameters can be derived from the four images in order to describe the state of polarisation of an object captured in the field of view. The modified design of the DTA QuadCam makes use of four small Raspberry Pi computers, so that each camera is controlled by its own computer in order to speed up the readout process and ensure that the four individual frames are taken simultaneously (to within 100-200 microseconds). In addition, a new firmware was requested from the camera manufacturer so that an output signal is generated to indicate the state of the camera shutter. A specialised GPS unit (also developed at DTA) is then used to monitor the shutter signals from the four cameras and record the actual time of exposure to an accuracy of about 100 microseconds. This makes the system well suited for the observation of fast-moving objects in the low Earth orbit (LEO). The QuadCam is currently mounted on a Paramount MEII robotic telescope mount at the newly built DTA space situational awareness observatory located on Whangaparaoa Peninsula near Auckland, New Zealand. The system will be used for tracking satellites in low Earth orbit and geostationary belt as well. The performance of the camera has been evaluated and a series of test images have been collected in order to derive the polarimetric signatures for selected satellites.

  5. Portable polarimetric fiber stress sensor system for visco-elastic and biomimetic material analysis

    Science.gov (United States)

    Harrison, Mark C.; Armani, Andrea M.

    2015-05-01

    Non-destructive materials characterization methods have significantly changed our fundamental understanding of material behavior and have enabled predictive models to be developed. However, the majority of these efforts have focused on crystalline and metallic materials, and transitioning to biomaterials, such as tissue samples, is non-trivial, as there are strict sample handling requirements and environmental controls which prevent the use of conventional equipment. Additionally, the samples are smaller and more complex in composition. Therefore, more advanced sample analysis methods capable of operating in these environments are needed. In the present work, we demonstrate an all-fiber-based material analysis system based on optical polarimetry. Unlike previous polarimetric systems which relied on free-space components, our method combines an in-line polarizer, polarization-maintaining fiber, and a polarimeter to measure the arbitrary polarization state of the output, eliminating all free-space elements. Additionally, we develop a more generalized theoretical analysis which allows more information about the polarization state to be obtained via the polarimeter. We experimentally verify our system using a series of elastomer samples made from polydimethylsiloxane (PDMS), a commonly used biomimetic material. By adjusting the base:curing agent ratio of the PDMS, we controllably tune the Young's modulus of the samples to span over an order of magnitude. The measured results are in good agreement with those obtained using a conventional load-frame system. Our fiber-based polarimetric stress sensor shows promise for use as a simple research tool that is portable and suitable for a wide variety of applications.

  6. WindSat Space Borne Polarimetric Microwave Radiometer: Data Products and System Performance

    Science.gov (United States)

    Truesdale, D.; Gaiser, P.; Bettenhausen, M. H.; Li, L.; Twarog, E.

    2017-12-01

    WindSat, a satellite-based multi-frequency polarimetric microwave radiometer developed by the Naval Research Laboratory for the U.S. Navy and the NPOESS Integrated Program Office (IPO), has collected over 14 years of fully-polarimetric microwave measurements from space since its launch in 2003. The primary WindSat mission was to demonstrate the capability to retrieve the ocean surface wind vector from a space-based microwave radiometer. The WindSat data is now being used to produce near-real-time products for the ocean surface wind vector, sea surface temperature (SST) and atmospheric columnar water vapor and cloud liquid water over the ocean at the U.S. Navy's Fleet Numerical Meteorological and Oceanographic Center (FNMOC). Several groups are assimilating WindSat data products into numerical weather models with positive results. In addition to providing environmental products over the ocean, the WindSat data set has been exploited for retrievals over land and ice. In particular, the WindSat channel set is well suited to retrieving soil moisture and land surface temperature. We have also built on heritage algorithms to derive sea ice concentration. This paper will provide highlights of WindSat environmental products. The success of the WindSat mission is directly traceable to the on-orbit sensor calibration. WindSat was designed with a one-year mission requirement and three year goal. Now in WindSat's fifteenth year on orbit, we continue to monitor the instrument performance and the calibration stability. Key system performance and calibration parameters include the receiver gains and NEDTs. These parameters are susceptible to component aging and changes in the payload thermal behavior. We will present trends in NEDT and receiver gains over the life of the mission. In addition to its primary mission, the long life of WindSat enables it to provide many forms of risk reduction and lessons learned for future microwave imagers.

  7. A Combined Use of Decomposition and Texture for Terrain Classification of Fully Polarimetric SAR Images

    Science.gov (United States)

    Rodionova, N. V.

    2007-03-01

    This p aper presents two-stag e unsupervised terrain classification of fully polarimetr ic SA R data using Freeman and Durden decomposition based on three simp le scattering mechanisms: surface, volume and double bounce (first step), and textur al features (uncorrelated uniformity , contr ast, inv erse mo men t and entropy) obtained from grey lev el co-occurrence matr ices (GLCM) (second step). Textural f eatures ar e defined in moving w indow 5x5 pixels w ith N=32 (N - number of grey lev els) . This algorith m preserves th e purity of domin ant polarimetric scattering properties and defines textural features in each scatter ing category. It is shown better object discrimin ation after app lying textur e w ith in fix ed scattering category. Speckle r eduction is one of th e main mo ments in imag e interpr etation improvement because of its great influen ce on textur e. Results from unfiltered and Lee filtered polar imetr ic SAR imag es show that the v alues of contrast and en tropy decr ease and th e values of uniformity and inverse moment increase with speckle reduction, that's tru e for all polarizations (HH, VV, HV). Th e d iscr imination b etw een objects increases after speckle f ilter ing. Polar ization influen ce on textur e features is def ined by calculating th e features in SAR images w ith HH , VV and HV polarizations before and after speck le filter ing, and then creating RG B images. It is shown mor e polarization inf luence on textur e features (uniformity , inverse mo ment and entropy) before filtering and less influen ce - after speck le f iltering. I t's not true for contrast wher e polar ization influen ce is not ch anged practically w ith filtering. SIR-C/X-SA R SLC L-band imag es of Moscow r egion are used for illustr ation.

  8. Feasibility Study of Rain Rate Monitoring from Polarimetric GNSS Propagation Parameters

    Directory of Open Access Journals (Sweden)

    Hao An

    2016-12-01

    Full Text Available In this work, the feasibility of estimating rain rate based on polarimetric Global Navigation Satellite Systems (GNSS signals is explored in theory. After analyzing the cause of polarimetric signals, three physical-mathematical relation models between co-polar phase shift (KHH, KVV, specific differential phase shift (KDP, and rain rate (R are respectively investigated. These relation models are simulated based on four different empirical equations of nonspherical raindrops and simulated Gamma raindrop size distribution. They are also respectively analyzed based on realistic Gamma raindrop size distribution and maximum diameter of raindrops under three different rain types: stratiform rain, cumuliform rain, and mixed clouds rain. The sensitivity of phase shift with respect to some main influencing factors, such as shape of raindrops, frequency, as well as elevation angle, is also discussed, respectively. The numerical results in this study show that the results by scattering algorithms T-matrix are consistent with those from Rayleigh Scattering Approximation. It reveals that they all have the possibility to estimate rain rate using the KHH-R, KVV-R or KDP-R relation. It can also be found that the three models are all affected by shape of raindrops and frequency, while the elevation angle has no effect on KHH-R. Finally, higher frequency L1 or B1 and lower elevation angle are recommended and microscopic characteristics of raindrops, such as shape and size distribution, are deemed to be important and required for further consideration in future experiments. Since phase shift is not affected by attenuation and not biased by ground clutter cancellers, this method has considerable potential in precipitation monitoring, which provides new opportunities for atmospheric research.

  9. Characterization of Mediterranean hail-bearing storms using an operational polarimetric X-band radar

    Directory of Open Access Journals (Sweden)

    G. Vulpiani

    2015-11-01

    It is based on an iterative approach that uses a very short-length (1 km moving window, allowing proper capture of the observed high radial gradients of the differential phase. The parameterization of the attenuation correction algorithm, which uses the reconstructed differential phase shift, is derived from electromagnetic simulations based on 3 years of drop size distribution (DSD observations collected in Rome (Italy. A fuzzy logic hydrometeor classification algorithm was also adopted to support the analysis of the storm characteristics. The precipitation field amounts were reconstructed using a combined polarimetric rainfall algorithm based on reflectivity and specific differential phase. The first storm was observed on 21 February when a winter convective system that originated in the Tyrrhenian Sea, marginally hit the central-eastern coastline of Sicily, causing a flash flood in Catania. Due to an optimal location (the system is located a few kilometers from the city center, it was possible to retrieve the storm characteristics fairly well, including the amount of rainfall field at the ground. Extemporaneous signal extinction, caused by close-range hail core causing significant differential phase shift in a very short-range path, is documented. The second storm, on 21 August 2013, was a summer mesoscale convective system that originated from a Mediterranean low pressure system lasting a few hours that eventually flooded the city of Syracuse. The undergoing physical process, including the storm dynamics, is inferred by analyzing the vertical sections of the polarimetric radar measurements. The high registered amount of precipitation was fairly well reconstructed, although with a trend toward underestimation at increasing distances. Several episodes of signal extinction were clearly manifested during the mature stage of the observed supercells.

  10. Co-localisation of the Kir6.2/SUR1 channel complex with glucagon-like peptide-1 and glucose-dependent insulinotrophic polypeptide expression in human ileal cells and implications for glycaemic control in new onset type 1 diabetes

    DEFF Research Database (Denmark)

    Nielsen, Lars Bo; Ploug, K.B.; Swift, P.

    2007-01-01

    The ATP-dependent K+-channel (K(ATP)) is critical for glucose sensing and normal glucagon and insulin secretion from pancreatic endocrine alpha- and beta-cells. Gastrointestinal endocrine L- and K-cells are also glucose-sensing cells secreting glucagon-like peptide-1 (GLP-1) and glucose-dependent......The ATP-dependent K+-channel (K(ATP)) is critical for glucose sensing and normal glucagon and insulin secretion from pancreatic endocrine alpha- and beta-cells. Gastrointestinal endocrine L- and K-cells are also glucose-sensing cells secreting glucagon-like peptide-1 (GLP-1) and glucose...

  11. Coordination of glucose and glutamine utilization by an expanded Myc network

    OpenAIRE

    Kaadige, Mohan R; Elgort, Marc G; Ayer, Donald E

    2010-01-01

    Glucose and glutamine are the most abundant circulating nutrients and support the growth and proliferation of all cells, in particular rapidly growing and dividing cancer cells. Several recent studies implicate an expanded Myc network in how cells sense and utilize both glucose and glutamine. These studies reveal an unappreciated coordination between glycolysis and glutaminolysis, potentially providing new targets for therapeutic intervention in cancer.

  12. Novel glucose fiber sensor combining ThFBG with GOD

    Science.gov (United States)

    Li, Mengmeng; Zhou, Ciming; Fan, Dian; Ou, Yiwen

    2016-10-01

    We propose a novel glucose fiber optic sensor combining a thinned cladding fiber Bragg grating (ThFBG) with glucose oxidase (GOD). By immobilizing GOD on the surface of a ThFBG, the fabricated sensor can obtain a high specificity to glucose. Because of the evanescent field, the sensor is very sensitive to the ambient refractive index change arising from the catalytic reaction between glucose and GOD. A four-level fiber model was simulated and verified the precision of the sensing principle. Two methods, glutaraldehyde crosslinking method (GCM) and 3-aminopropyl triethoxysilane covalent coupling method (ATCCM), were experimentally utilized to immobilize GOD. And sensor fabricated with the method ATCCM shows a measurement range of 0-0.82 mg/mL which is better than the sensor fabricated with the method GCM with measurement range of 0-0.67 mg/mL under the same condition. By using ATCCM to immobilize GOD with different concentrations, three sensors were fabricated and used for glucose measurement by monitoring the Bragg wavelength (λb) shifts, the results indicate a good linear relationship between wavelength shift and glucose concentration within a specific range, and the measurement range increases as GOD concentration increases. The highest sensitivity of sensor reaches up to 0.0549 nm/(mg.mL-1). The proposed sensor has distinct advantages in sensing structure, cost and specificity.

  13. A Novel Ship Detection Method Using Model-Based Decomposition as a Polarimetric Band-Stop Filter

    Science.gov (United States)

    Sugimoto, Mitsunobu; Marino, Armando; Ouchi, Kazuo; Nakamura, Yasuhiro

    2013-08-01

    In this study, a novel ship detection method using model-based decomposition is suggested. The model-based decomposition is one of the popular analytical methods of POLSAR (polarimetric SAR) data. Since most of the scattering on the sea is surface scattering, the model-based decomposition can be used as a band-stop filter, to block out surface scattering component. As a result, ships, which generally have more complex scattering process, can be detected. Advanced Land Observation Satellite-Phased Array L-band SAR (ALOS-PALSAR) polarimetric SAR data and available reference data for validation are used in the study. The result was processed using adaptive-CFAR (constant false alarm rate) technique and compared with the reference data.

  14. Remote Sensing

    Indian Academy of Sciences (India)

    application area. RS data in conjunction with collateral data has greatly facilitated integrated development of land and water resources on watershed basis leading to sustainable develop- ment. Disaster monitoring, damage assessment and mitigation has been a main beneficiary of spaceborne remote sensing. Sequen-.

  15. Pervasive sensing

    Science.gov (United States)

    Nagel, David J.

    2000-11-01

    The coordinated exploitation of modern communication, micro- sensor and computer technologies makes it possible to give global reach to our senses. Web-cameras for vision, web- microphones for hearing and web-'noses' for smelling, plus the abilities to sense many factors we cannot ordinarily perceive, are either available or will be soon. Applications include (1) determination of weather and environmental conditions on dense grids or over large areas, (2) monitoring of energy usage in buildings, (3) sensing the condition of hardware in electrical power distribution and information systems, (4) improving process control and other manufacturing, (5) development of intelligent terrestrial, marine, aeronautical and space transportation systems, (6) managing the continuum of routine security monitoring, diverse crises and military actions, and (7) medicine, notably the monitoring of the physiology and living conditions of individuals. Some of the emerging capabilities, such as the ability to measure remotely the conditions inside of people in real time, raise interesting social concerns centered on privacy issues. Methods for sensor data fusion and designs for human-computer interfaces are both crucial for the full realization of the potential of pervasive sensing. Computer-generated virtual reality, augmented with real-time sensor data, should be an effective means for presenting information from distributed sensors.

  16. COMPARISON BETWEEN SPECTRAL, SPATIAL AND POLARIMETRIC CLASSIFICATION OF URBAN AND PERIURBAN LANDCOVER USING TEMPORAL SENTINEL – 1 IMAGES

    Directory of Open Access Journals (Sweden)

    K. Roychowdhury

    2016-06-01

    Full Text Available Landcover is the easiest detectable indicator of human interventions on land. Urban and peri-urban areas present a complex combination of landcover, which makes classification challenging. This paper assesses the different methods of classifying landcover using dual polarimetric Sentinel-1 data collected during monsoon (July and winter (December months of 2015. Four broad landcover classes such as built up areas, water bodies and wetlands, vegetation and open spaces of Kolkata and its surrounding regions were identified. Polarimetric analyses were conducted on Single Look Complex (SLC data of the region while ground range detected (GRD data were used for spectral and spatial classification. Unsupervised classification by means of K-Means clustering used backscatter values and was able to identify homogenous landcovers over the study area. The results produced an overall accuracy of less than 50% for both the seasons. Higher classification accuracy (around 70% was achieved by adding texture variables as inputs along with the backscatter values. However, the accuracy of classification increased significantly with polarimetric analyses. The overall accuracy was around 80% in Wishart H-A-Alpha unsupervised classification. The method was useful in identifying urban areas due to their double-bounce scattering and vegetated areas, which have more random scattering. Normalized Difference Built-up index (NDBI and Normalized Difference Vegetation Index (NDVI obtained from Landsat 8 data over the study area were used to verify vegetation and urban classes. The study compares the accuracies of different methods of classifying landcover using medium resolution SAR data in a complex urban area and suggests that polarimetric analyses present the most accurate results for urban and suburban areas.

  17. Precipitation microphysics characteristics of a Typhoon Matmo (2014) rainband after landfall over eastern China based on polarimetric radar observations

    Science.gov (United States)

    Wang, Mingjun; Zhao, Kun; Xue, Ming; Zhang, Guifu; Liu, Su; Wen, Long; Chen, Gang

    2016-10-01

    The evolution of microphysical characteristics of a rainband in Typhoon Matmo (2014) over eastern China, through its onset, developing, mature, and dissipating stages, is documented using observations from an S band polarimetric Doppler radar and a two-dimensional video disdrometer (2DVD). The drop size distributions observed by the 2DVD and retrieved from the polarimetric radar measurements indicate that the convection in the rainband generally contains smaller drops and higher number concentrations than the typical maritime type convection described in Bringi et al. (2003). The average mass-weighted mean diameter (Dm) of convective precipitation in the rainband is about 1.41 mm, and the average logarithmic normalized intercept (Nw) is 4.67 log10 mm-1 m-3. To further investigate the dominant microphysical processes, the evolution of the vertical structures of polarimetric variables is examined. Results show that complex ice processes are involved above the freezing level, while it is most likely that the accretion and/or coalescence processes dominate below the freezing level throughout the rainband life cycle. A combined examination of the polarimetric measurements and profiles of estimated vertical liquid and ice water contents indicates that the conversion of cloud water into rainwater through cloud water accretion by raindrops plays a dominant role in producing heavy rainfall. The high estimated precipitation efficiency of 50% also suggests that cloud water accretion is the dominant mechanism for producing heavy rainfall. This study represents the first time that radar and 2DVD observations are used together to characterize the microphysical characteristics and precipitation efficiency for typhoon rainbands in China.

  18. Polarimetric survey of main-belt asteroids. IV. New results from the first epoch of the CASLEO survey

    Science.gov (United States)

    Gil-Hutton, R.; Cellino, A.; Bendjoya, Ph.

    2014-09-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 1995, and until 2012 data on a large sample of asteroids were obtained. We here present and analyze the unpublished results for 129 asteroids of different taxonomic types, 56 which were polarimetrically observed for the first time. We find that the asteroids (402) Chloe and (729) Watsonia are Barbarians, and asteroid (269) Justitia shows a phase - polarization curve that seems to have a small inversion angle. Data obtained in UBVRI colors allow us to sketch an analysis of the wavelength dependence of the degree of linear polarization for 31 asteroids, in spite of some large error bars in some cases. Based on observations carried out at the Complejo Astronómico El Leoncito, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/569/A122

  19. Evaluation of Digital Classification of Polarimetric SAR Data for Iron-Mineralized Laterites Mapping in the Amazon Region

    Directory of Open Access Journals (Sweden)

    Cleber G. Oliveira

    2013-06-01

    Full Text Available This study evaluates the potential of C- and L-band polarimetric SAR data for the discrimination of iron-mineralized laterites in the Brazilian Amazon region. The study area is the N1 plateau located on the northern border of the Carajás Mineral Province, the most important Brazilian mineral province which has numerous mineral deposits, particularly the world’s largest iron deposits. The plateau is covered by low-density savanna-type vegetation (campus rupestres which contrasts visibly with the dense equatorial forest. The laterites are subdivided into three units: chemical crust, iron-ore duricrust, and hematite, of which only the latter two are of economic interest. Full polarimetric data from the airborne R99B sensor of the SIVAM/CENSIPAM (L-band system and the RADARSAT-2 satellite (C-band were evaluated. The study focused on an assessment of distinct schemes for digital classification based on decomposition theory and hybrid approach, which incorporates statistical analysis as input data derived from the target decomposition modeling. The results indicated that the polarimetric classifications presented a poor performance, with global Kappa values below 0.20. The accuracy for the identification of units of economic interest varied from 55% to 89%, albeit with high commission error values. In addition, the results using L-band were considered superior compared to C-band, which suggest that the roughness scale for laterite discrimination in the area is nearer to L than to C-band.

  20. EFFECT OF POLARIMETRIC NOISE ON THE ESTIMATION OF TWIST AND MAGNETIC ENERGY OF FORCE-FREE FIELDS

    International Nuclear Information System (INIS)

    Tiwari, Sanjiv Kumar; Venkatakrishnan, P.; Gosain, Sanjay; Joshi, Jayant

    2009-01-01

    The force-free parameter α, also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global value of α for a whole active region gives the degree of twist per unit axial length. We investigate the effect of polarimetric noise on the calculation of global α value and magnetic energy of an analytical bipole. The analytical bipole has been generated using the force-free field approximation with a known value of constant α and magnetic energy. The magnetic parameters obtained from the analytical bipole are used to generate Stokes profiles from the Unno-Rachkovsky solutions for polarized radiative transfer equations. Then we add random noise of the order of 10 -3 of the continuum intensity (I c ) in these profiles to simulate the real profiles obtained by modern spectropolarimeters such as Hinode (SOT/SP), SVM (USO), ASP, DLSP, POLIS, and SOLIS etc. These noisy profiles are then inverted using a Milne-Eddington inversion code to retrieve the magnetic parameters. Hundred realizations of this process of adding random noise and polarimetric inversion is repeated to study the distribution of error in global α and magnetic energy values. The results show that (1) the sign of α is not influenced by polarimetric noise and very accurate values of global twist can be calculated, and (2) accurate estimation of magnetic energy with uncertainty as low as 0.5% is possible under the force-free condition.