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Sample records for absorption spectrophotometer prior

  1. A Low-Cost Quantitative Absorption Spectrophotometer

    ERIC Educational Resources Information Center

    Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

    2012-01-01

    In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

  2. Computer-Graphics Emulation of Chemical Instrumentation: Absorption Spectrophotometers.

    ERIC Educational Resources Information Center

    Gilbert, D. D.; And Others

    1982-01-01

    Describes interactive, computer-graphics program emulating behavior of high resolution, ultraviolet-visible analog recording spectrophotometer. Graphics terminal behaves as recording absorption spectrophotometer. Objective of the emulation is study of optimization of the instrument to yield accurate absorption spectra, including…

  3. 21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and...

  4. 21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and...

  5. 21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and...

  6. White light photothermal lens spectrophotometer for the determination of absorption in scattering samples.

    PubMed

    Marcano, Aristides; Alvarado, Salvador; Meng, Junwei; Caballero, Daniel; Moares, Ernesto Marín; Edziah, Raymond

    2014-01-01

    We developed a pump-probe photothermal lens spectrophotometer that uses a broadband arc-lamp and a set of interference filters to provide tunable, nearly monochromatic radiation between 370 and 730 nm as the pump light source. This light is focused onto an absorbing sample, generating a photothermal lens of millimeter dimensions. A highly collimated monochromatic probe light from a low-power He-Ne laser interrogates the generated lens, yielding a photothermal signal proportional to the absorption of light. We measure the absorption spectra of scattering dye solutions using the device. We show that the spectra are not affected by the presence of scattering, confirming that the method only measures the absorption of light that results in generation of heat. By comparing the photothermal spectra with the usual absorption spectra determined using commercial transmission spectrophotometers, we estimate the quantum yield of scattering of the sample. We discuss applications of the device for spectroscopic characterization of samples such as blood and gold nanoparticles that exhibit a complex behavior upon interaction with light.

  7. Assessing the Engagement, Learning, and Overall Experience of Students Operating an Atomic Absorption Spectrophotometer with Remote Access Technology

    ERIC Educational Resources Information Center

    Erasmus, Daniel J.; Brewer, Sharon E.; Cinel, Bruno

    2015-01-01

    The use of internet-based technologies in the teaching of laboratories has emerged as a promising education tool. This study evaluated the effectiveness of using remote access technology to operate an atomic absorption spectrophotometer in analyzing the iron content in a crude myoglobin extract. Sixty-two students were surveyed on their level of…

  8. Determination of mercury by cold vapor atomic absorption spectrophotometer in Tongkat Ali preparations obtained in Malaysia.

    PubMed

    Ang, Hooi-Hoon; Lee, Ee-Lin; Cheang, Hui-Seong

    2004-01-01

    The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency. PMID:15162849

  9. [Determination of soil exchangeable base cations by using atomic absorption spectrophotometer and extraction with ammonium acetate].

    PubMed

    Zhang, Yu-ge; Xiao, Min; Dong, Yi-hua; Jiang, Yong

    2012-08-01

    A method to determine soil exchangeable calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) by using atomic absorption spectrophotometer (AAS) and extraction with ammonium acetate was developed. Results showed that the accuracy of exchangeable base cation data with AAS method fits well with the national standard referential soil data. The relative errors for parallel samples of exchangeable Ca and Mg with 66 pair samples ranged from 0.02%-3.14% and 0.06%-4.06%, and averaged to be 1.22% and 1.25%, respectively. The relative errors for exchangeable K and Na with AAS and flame photometer (FP) ranged from 0.06%-8.39% and 0.06-1.54, and averaged to be 3.72% and 0.56%, respectively. A case study showed that the determination method for exchangeable base cations by using AAS was proven to be reliable and trustable, which could reflect the real situation of soil cation exchange properties in farmlands. PMID:23156790

  10. Assessing the engagement, learning, and overall experience of students operating an atomic absorption spectrophotometer with remote access technology.

    PubMed

    Erasmus, Daniel J; Brewer, Sharon E; Cinel, Bruno

    2015-01-01

    The use of internet-based technologies in the teaching of laboratories has emerged as a promising education tool. This study evaluated the effectiveness of using remote access technology to operate an atomic absorption spectrophotometer in analyzing the iron content in a crude myoglobin extract. Sixty-two students were surveyed on their level of engagement, learning, and overall experience. Feedback from students suggests that the use of remote access technology is effective in teaching students the principles of chemical analysis by atomic absorption spectroscopy.

  11. Assessment of toxic metals in raw and processed milk samples using electrothermal atomic absorption spectrophotometer.

    PubMed

    Kazi, Tasneem Gul; Jalbani, Nusrat; Baig, Jameel Ahmed; Kandhro, Ghulam Abbas; Afridi, Hassan Imran; Arain, Mohammad Balal; Jamali, Mohammad Khan; Shah, Abdul Qadir

    2009-09-01

    Milk and dairy products have been recognized all over the world for their beneficial influence on human health. The levels of toxic metals (TMs) are an important component of safety and quality of milk. A simple and efficient microwave assisted extraction (MAE) method has been developed for the determination of TMs (Al, Cd, Ni and Pb), in raw and processed milk samples. A Plackett-Burman experimental design and 2(3)+star central composite design, were applied in order to determine the optimum conditions for MAE. Concentrations of TMs were measured by electrothermal atomic absorption spectrometry. The accuracy of the optimized procedure was evaluated by standard addition method and conventional wet acid digestion method (CDM), for comparative purpose. No significant differences were observed (P>0.05), when comparing the values obtained by the proposed MAE method and CDM (paired t-test). The average relative standard deviation of the MAE method varied between 4.3% and 7.6% based on analyte (n=6). The proposed method was successfully applied for the determination of understudy TMs in milk samples. The results of raw and processed milk indicated that environmental conditions and manufacturing processes play a key role in the distribution of toxic metals in raw and processed milk.

  12. Intersstellar absorption lines between 2000 and 3000 A in nearby stars observed with BUSS. [Balloon Borne Ultraviolet Spectrophotometer

    NASA Technical Reports Server (NTRS)

    De Boer, K. S.; Lenhart, H.; Van Der Hucht, K. A.; Kamperman, T. M.; Kondo, Y.

    1986-01-01

    Spectra obtained between 2000 and 3000 A with the Balloon Borne Ultraviolet Spectrophotometer (BUSS) payload were examined for interstellar absorption lines. In bright stars, with spectral types between O9V and F5V, such lines were measured of Mg I, Mg II, Cr II, Mn II, Fe II and Zn II, with Cr II and Zn II data of especially high quality. Column densities were derived and interstellar abundances were determined for the above species. It was found that metal depletion increases with increasing E(B-V); Fe was most affected and Zn showed a small depletion for E(B-V) greater than 0.3 towards Sco-Oph. The metal column densities, derived for Alpha-And, Kappa-Dra, Alpha-Com, Alpha-Aql, and 29 Cyg were used to infer N(H I). It was shown that the ratio of Mg I to Na I is instrumental in determining the ionization structure along each line of sight. The spectra of Aql stars confirms the presence of large gas densities near Alpha-Oph. Moreover, data indicated that the Rho-Oph N(H I) value needs to be altered to 35 x 10 to the 20th/sq cm, based on observed ion ratios and analysis of the Copernicus L-alpha profile.

  13. Simultaneous detection of the absorption spectrum and refractive index ratio with a spectrophotometer: monitoring contaminants in bioethanol

    NASA Astrophysics Data System (ADS)

    Kontturi, V.; Hyvärinen, S.; García, A.; Carmona, R.; Murzin, D. Yu; Mikkola, J.-P.; Peiponen, K.-E.

    2011-05-01

    The optical properties of a biofuel resulting from the fungi-treated lignocellulosic biomass in an ethanol matrix were studied. The matrix simulates the case that the bioethanol is contaminated by sugars, water and colour pigments that reduce the quality of the biofuel and compromise the combustion process. It is suggested that by applying a spectrophotometer only, it is possible to obtain valid information, i.e. the spectral features of the contaminants as well as the refractive index ratio of bioethanol. This allows for simultaneous purity and density detection of biomass-derived liquids or liquid biofuels, in comparison to a reference representing an ideal bioethanol (pure ethyl alcohol, ethanol of 99.5% purity (v/v)).

  14. A Simple Spectrophotometer Using Common Materials and a Digital Camera

    ERIC Educational Resources Information Center

    Widiatmoko, Eko; Widayani; Budiman, Maman; Abdullah, Mikrajuddin; Khairurrijal

    2011-01-01

    A simple spectrophotometer was designed using cardboard, a DVD, a pocket digital camera, a tripod and a computer. The DVD was used as a diffraction grating and the camera as a light sensor. The spectrophotometer was calibrated using a reference light prior to use. The spectrophotometer was capable of measuring optical wavelengths with a…

  15. Method development for the determination of fluorine in toothpaste via molecular absorption of aluminum mono fluoride using a high-resolution continuum source nitrous oxide/acetylene flame atomic absorption spectrophotometer.

    PubMed

    Ozbek, Nil; Akman, Suleyman

    2012-05-30

    Fluorine was determined via the rotational molecular absorption line of aluminum mono fluoride (AlF) generated in C(2)H(2)/N(2)O flame at 227.4613 nm using a high-resolution continuum source flame atomic absorption spectrophotometer (HR-CS-FAAS). The effects of AlF wavelength, burner height, fuel rate (C(2)H(2)/N(2)O) and amount of Al on the accuracy, precision and sensitivity were investigated and optimized. The Al-F absorption band at 227.4613 nm was found to be the most suitable analytical line with respect to sensitivity and spectral interferences. Maximum sensitivity and a good linearity were obtained in acetylene-nitrous oxide flame at a flow rate of 210 L h(-1) and a burner height of 8mm using 3000 mg L(-1) of Al for 10-1000 mg L(-1)of F. The accuracy and precision of the method were tested by analyzing spiked samples and waste water certified reference material. The results were in good agreement with the certified and spiked amounts as well as the precision of several days during this study was satisfactory (RSD<10%). The limit of detection and characteristic concentration of the method were 5.5 mg L(-1) and 72.8 mg L(-1), respectively. Finally, the fluorine concentrations in several toothpaste samples were determined. The results found and given by the producers were not significantly different. The method was simple, fast, accurate and sensitive.

  16. [The content of mineral elements in Camellia olei fera ovary at pollination and fertilization stages determined by auto discrete analyzers and atomic absorption spectrophotometer].

    PubMed

    Zou, Feng; Yuan, De-Yi; Gao, Chao; Liao, Ting; Chen, Wen-Tao; Han, Zhi-Qiang; Zhang, Lin

    2014-04-01

    In order to elucidate the nutrition of Camellia olei fera at pollination and fertilization stages, the contents of mineral elements were determined by auto discrete analyzers and atomic absorption spectrophotometer, and the change in the contents of mineral elements was studied and analysed under the condition of self- and cross-pollination. The results are showed that nine kinds of mineral elements contents were of "S" or "W" type curve changes at the pollination and fertilization stages of Camellia olei fera. N, K, Zn, Cu, Ca, Mn element content changes showed "S" curve under the self- and out-crossing, the content of N reaching the highest was 3.445 8 mg x g(-1) in self-pollination of 20 d; K content reaching the highest at the cross-pollination 20 d was 6.275 5 mg x g(-1); Zn content in self-pollination of 10 d reaching the highest was 0.070 5 mg x g(-1); Cu content in the cross-pollination of 5 d up to the highest was 0.061 0 mg x g(-1); Ca content in the cross-pollination of 15 d up to the highest was 3.714 5 mg x g(-1); the content of Mn reaching the highest in self-pollination 30 d was 2. 161 5 mg x g(-1). Fe, P, Mg element content changes was of "S" type curve in selfing and was of "W" type curve in outcrossing, Fe content in the self-pollination 10 d up to the highest was 0.453 0 mg x g(-1); P content in self-pollination of 20 d reaching the highest was 6.731 8 mg x g(-1); the content of Mg up to the highest in self-pollination 25 d was 2.724 0 mg x g(-1). The results can be used as a reference for spraying foliar fertilizer, and improving seed setting rate and yield in Camellia olei fera.

  17. Dobson ozone spectrophotometer modification.

    NASA Technical Reports Server (NTRS)

    Komhyr, W. D.; Grass, R. D.

    1972-01-01

    Description of a modified version of the Dobson ozone spectrophotometer in which several outdated electronic design features have been replaced by circuitry embodying more modern design concepts. The resulting improvement in performance characteristics has been obtained without changing the principle of operation of the original instrument.

  18. Impact of energy-related pollutants on chromosome structure. Progress report, January 1-December 31, 1980. IQUID COLUMN CHROMATOGRAPHY; ABSORPTION SPECTRA; COMPUTER CODES; DICHROISM; EQUIPMENT INTERFACES; MICROPROCESSORS; SPECTROPHOTOMETERS; ; CARBON 13; COMPLEXES; NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Not Available

    1980-01-01

    Methods for rapidly analyzing methylated and ethylated nucleosides and bases by high pressure liquid chromatography were investigated. Deoxyribonucleotides were alkylated with alkyl iodides and dialkyl sulfates. Several unreported products of the reactions of methyl and ethyl iodide in dimethylsulfoxide were found and are being characterized. The Cary 219 UV-Vis spectrophotometer was interfaced to a microcomputer and several utility programs were written. Preliminary absorption and circular dichroism studies of the binding of ethidium to DNA and nucleosome cores showed binding to cores to be quite different from binding to DNA. Free radical and additional reactions of bisulfite with DNA in chromatin were examined. Free radical attack was minimal. Some conversion of cytosine to uracil was noted, but protein crosslinking to DNA was not detected. The first valid natural abundance /sup 13/C nmr spectra of double-stranded DNA and double-stranded DNA complexed with ethidium were obtained. These spectra suggested that DNA undergoes considerable internal motion. The data show that 13-C nmr studies of the conformational and motional properties of native DNA and of complexes of native DNA with small molecules are practical and promising. Studies of subnucleosomes derived from nucleosomes were completed. Based on these studies, a model of the linear arrangement of histone C-terminal and N-terminal chain regions along nucleosome DNA was proposed. The use of staphylococcal protease to probe histone conformations in nucleosomes was explored. Preliminary data indicate that H3 is much more susceptible to protease than other core histones, and is cleaved in its hydrophobic domain. A procedure for fractionating chromatin was alos developed. (ERB)

  19. A UV-Vis photoacoustic spectrophotometer.

    PubMed

    Wiegand, Joseph R; Mathews, L Dalila; Smith, Geoffrey D

    2014-06-17

    A novel photoacoustic spectrophotometer (PAS) for the measurement of gas-phase and aerosol absorption over the UV-visible region of the spectrum is described. Light from a broadband Hg arc lamp is filtered in eight separate bands from 300 to 700 nm using bandpass interference filters (centered at 301 nm, 314 nm, 364 nm, 405 nm, 436 nm, 546 nm, 578 and 687 nm) and modulated with an optical chopper before entering the photoacoustic cell. All wavelength bands feature a 20-s detection limit of better than 3.0 Mm(-1) with the exception of the lower-intensity 687 nm band for which it is 10.2 Mm(-1). Validation measurements of gas-phase acetone and nigrosin aerosol absorption cross sections at several wavelengths demonstrate agreement to within 10% with those measured previously (for acetone) and those predicted by Mie theory (for nigrosin). The PAS instrument is used to measure the UV-visible absorption spectrum of ambient aerosol demonstrating a dramatic increase in the UV region with absorption increasing by 300% from 405 to 301 nm. This type of measurement throughout the UV-visible region and free from artifacts associated with filter-based methods has not been possible previously, and we demonstrate its promise for classifying and quantifying different types of light-absorbing ambient particles. PMID:24905953

  20. Coacervative extraction of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Hagarová, Ingrid; Bujdoš, Marek; Matúš, Peter; Kubová, Jana

    2013-10-01

    In this work, a relatively simple and sensitive method for separation/preconcentration of trace lead from natural waters prior to its determination by electrothermal atomic absorption spectrometry has been proposed. The method is based on the extraction of Pb-dithizone chelate with coacervates made up of lauric acid in the presence of potassium ions and methanol. Several important factors affecting extraction efficiency such as pH, concentration of lauric acid and dithizone, ionic strength, incubation and centrifugation time were investigated and optimized. After separation of aqueous bulk solution from surfactant-rich phase, the final extract was redissolved by using 500 μl of methanol acidified with 0.2 mol l- 1 HNO3. Under the optimized conditions (using initial sample volume of 10 ml), enrichment factor of 17.0, detection limit of 0.12 μg l- 1, quantification limit of 0.38 μg l- 1, relative standard deviation of 4.2% (for 2 μg l- 1 of Pb; n = 26), linearity of the calibration graph in the range of 0.5-4.0 μg l- 1 (with correlation coefficient better than 0.995) were achieved. The method was validated by the analysis of certified reference material (TMDA-61). Extraction recoveries for the CRM, spiked model solutions and spiked natural water samples were in the range of 91-96%. Finally, the method was applied to the separation/preconcentration and determination of trace lead in natural waters.

  1. Fiber Optic Spectrophotometer With Photodiode Linear Array

    NASA Astrophysics Data System (ADS)

    Velluet, M. T.; Blanc, F.; Vernet, P.

    1989-01-01

    Spectrophotometric measurements are used in a great number of industrial processes (chemical, pharmaceutical, farm-produce...) in nuclear environment and with optical precision components. Especially the evolution of a chemical process or of an optical coating could be followed by these measurements. Spectrophotometers, using optical fibers to transport the signal out of the instrument make possible the measurement "in-situ" and in real time. The advantage of using a diode array to detect the signal is an instantaneous measurement all over the spectral range without moving parts. It allows an excellent reproductibility of the measurements. The instrument is controlled by a micro computer. The spectrophotometer will be described and its technical performs presented. An extension using optical fibers on a "classical" spectrophotometer (a H.P. one) will be also described and its technical performs with such a system presented.

  2. Enzyme Activity Experiments Using a Simple Spectrophotometer

    ERIC Educational Resources Information Center

    Hurlbut, Jeffrey A.; And Others

    1977-01-01

    Experimental procedures for studying enzyme activity using a Spectronic 20 spectrophotometer are described. The experiments demonstrate the effect of pH, temperature, and inhibitors on enzyme activity and allow the determination of Km, Vmax, and Kcat. These procedures are designed for teaching large lower-level biochemistry classes. (MR)

  3. The Fuge Tube Diode Array Spectrophotometer

    ERIC Educational Resources Information Center

    Arneson, B. T.; Long, S. R.; Stewart, K. K.; Lagowski, J. J.

    2008-01-01

    We present the details for adapting a diode array UV-vis spectrophotometer to incorporate the use of polypropylene microcentrifuge tubes--fuge tubes--as cuvettes. Optical data are presented validating that the polyethylene fuge tubes are equivalent to the standard square cross section polystyrene or glass cuvettes generally used in…

  4. Applied Electronics: Construction of a Simple Spectrophotometer

    NASA Astrophysics Data System (ADS)

    Thal, Melissa A.; Samide, Michael J.

    2001-11-01

    In this paper we describe the construction of a simple spectrophotometer intended for use as a capstone circuit for an electronics laboratory exercise. Students in the undergraduate laboratory have learned basic circuitry and are now able to read a schematic and construct an instrument that has practical applications in chemical analysis. A simple LED is used as the source and is easily changed to correspond to different species being studied. Detection is accomplished through the use of one of three signal transducers (a photoresistor, a photodiode, or a photodarlington) and a current-to-voltage converter. A box lined with black felt is used to shield the spectrophotometer from ambient light. This spectrophotometer shows excellent Beer-Lambert law linearity over a large concentration range and has been used in the laboratory to determine the concentration of a metal cation in solution on the basis of a calibration curve. Of the transducers used, the photoresistor showed the best response at multiple wavelengths with error in concentration determination not greater than 6%. Through the building and testing of this circuit, the students can visualize applications of electronic circuitry.

  5. Normal Incidence Spectrophotometer Film Thickness Measurement Tool

    NASA Astrophysics Data System (ADS)

    Manning, S. A.

    1983-05-01

    The Normal Incidence Spectrophotometer (NIS) Measurement Tool is used to automatically measure the thickness of transparent films on silicon wafers. Under the control of an IBM. System 7 computer, both, wafer handling and the thickness measurement are performed. automatically. Wafers are transported through the tool on a covered airtrack, and after posi-tioning in a vacuum, chuck, are moved under the measurement head to pre-programmed measurement sites. Reflectivity data from the wafer surface, as a function of wavelength, is used by a software algorithm to calculate film, thickness. This tool is used on advanced manufacturing lines at IBM in both. East Fishkill, N.Y. and Burlington, Vt.

  6. Solid phase extraction of gold(III) on Amberlite XAD-2000 prior to its flame atomic absorption spectrometric determination.

    PubMed

    Elci, Latif; Sahan, Derya; Basaran, Aydan; Soylak, Mustafa

    2007-09-01

    A solid phase extraction method for the determination of gold(III) at trace levels by flame atomic absorption spectrometer (FAAS) was developed. The method was based on retention of gold as chloro complexes through the Amberlite XAD-2000. The effect of some analytical parameters including hydrochloric acid concentration, sample volume, sample and eluent flow rates, eluent volume, eluent concentration and interfering ions on the recovery of gold(III) was investigated. The retention of gold(III) from 1.5 mol l(-1) HCl solution and the recovery of gold with 0.07 mol l(-1) NH3 solution were quantitative (>or=95%). The relative standard deviation (RSD) was calculated as 3.2% (n = 10). The detection limit for gold was 2 microg l(-1). The accuracy was checked with the determination of gold spiked an artificial seawater and a pure copper samples.

  7. Solid phase extraction of gold(III) on Amberlite XAD-2000 prior to its flame atomic absorption spectrometric determination.

    PubMed

    Elci, Latif; Sahan, Derya; Basaran, Aydan; Soylak, Mustafa

    2007-09-01

    A solid phase extraction method for the determination of gold(III) at trace levels by flame atomic absorption spectrometer (FAAS) was developed. The method was based on retention of gold as chloro complexes through the Amberlite XAD-2000. The effect of some analytical parameters including hydrochloric acid concentration, sample volume, sample and eluent flow rates, eluent volume, eluent concentration and interfering ions on the recovery of gold(III) was investigated. The retention of gold(III) from 1.5 mol l(-1) HCl solution and the recovery of gold with 0.07 mol l(-1) NH3 solution were quantitative (>or=95%). The relative standard deviation (RSD) was calculated as 3.2% (n = 10). The detection limit for gold was 2 microg l(-1). The accuracy was checked with the determination of gold spiked an artificial seawater and a pure copper samples. PMID:17180414

  8. RECALIBRATION OF H CANYON ONLINE SPECTROPHOTOMETER AT EXTENDED URANIUM CONCENTRATION

    SciTech Connect

    Lascola, R

    2008-10-29

    The H Canyon online spectrophotometers are calibrated for measurement of the uranium and nitric acid concentrations of several tanks in the 2nd Uranium Cycle.[1] The spectrometers, flow cells, and prediction models are currently optimized for a process in which uranium concentrations are expected to range from 0-15 g/L and nitric acid concentrations from 0.05-6 M. However, an upcoming processing campaign will involve 'Super Kukla' material, which has a lower than usual enrichment of fissionable uranium. Total uranium concentrations will be higher, spanning approximately 0-30 g/L U, with no change in the nitric acid concentrations. The new processing conditions require the installation of new flow cells with shorter path lengths. As the process solutions have a higher uranium concentration, the shorter path length is required to decrease the absorptivity to values closer to the optimal range for the instrument. Also, new uranium and nitric acid prediction models are required to span the extended uranium concentration range. The models will be developed for the 17.5 and 15.4 tanks, for which nitric acid concentrations will not exceed 1 M. The restricted acid range compared to the original models is anticipated to reduce the measurement uncertainty for both uranium and nitric acid. The online spectrophotometers in H Canyon Second Uranium Cycle were modified to allow measurement of uranium and nitric acid for the Super Kukla processing campaign. The expected uranium concentrations, which are higher than those that have been recently processed, required new flow cells with one-third the optical path length of the existing cells. Also, new uranium and nitric acid calibrations were made. The estimated reading uncertainties (2{sigma}) for Tanks 15.4 and 17.5 are {approx}5% for uranium and {approx}25% for nitric acid.

  9. Optics characterization with compact EUV spectrophotometer

    NASA Astrophysics Data System (ADS)

    Blaschke, H.; Balasa, I.; Koch, L.; Starke, K.; Ristau, D.; Wies, C.; Lebert, R.; Bayer, A.; Barkusky, F.; Mann, K.

    2008-03-01

    The development of a novel compact EUV spectrophotometer will be presented. The device is capable of measuring reflectance and transmittance spectra of medium scale EUV-optics primary in the spectral range from 12nm to 21nm. Based on a new polychromatic measurement principle, the system uses the direct irradiation of a table-top EUV-source for illuminating the sample and a broad-band spectrograph for detecting the probe and reference beam. Samples can be investigated under different angles of incidence and in respect of lateral dependencies. Typical results of reflectivity investigations of Mo/Si-mirrors and transmitting foils will be shown and compared with reference measurements of certified institutes and calculations.

  10. Evaluation of cadmium in greenhouse soils and agricultural products of Jiroft (Iran) using microwave digestion prior to atomic absorption spectrometry determination.

    PubMed

    Afzali, Daryoush; Fathirad, Fariba; Afzali, Zahra; Majdzadeh-Kermani, Seyed Mohammad Javad

    2015-03-01

    This study determines total levels of potentially toxic trace element, Cd (II) in Jiroft (Kerman, Iran) greenhouse soil and agricultural products that are grown in these greenhouses (tomatoes and cucumbers), and the comparison with soil outside of greenhouse using microwave digestion prior to flame atomic absorption spectrometry determination. The results show that the cadmium concentration in greenhouse soil is 0.9-1.9 mg kg(-1) and out of greenhouse is 0.4-1.0 mg kg(-1). Also, cadmium concentration range in tomatoes and cucumbers is about 0.07-0.40 mg kg(-1). The obtained results show that the concentration of this metal in greenhouse soil is higher than outside soil samples and is below the safe limit.

  11. Continuous approach for ultrasound-assisted acid extraction-minicolumn preconcentration of chromium and cobalt from seafood samples prior to flame atomic absorption spectrometry.

    PubMed

    Yebra-Biurrun, Maria C; Cancela-Pérez, Sheila

    2007-08-01

    A rapid and sensitive method has been proposed for the determination of chromium and cobalt in seafood samples by flame atomic absorption spectrometry combined with a dynamic ultrasound-assisted acid extraction and an on-line minicolumn preconcentration. The use of diluted nitric acid as extractant in a continuous mode at a flow rate of 3.5 mL min(-1) and room temperature was sufficient for quantitative extraction of these trace metals from seafoods. A minicolumn containing a chelating resin was an excellent device for the quantitative preconcentration of chromium and cobalt prior to their detection. A flow-injection manifold was used as interface for coupling all analytical steps, which allowed the automation of the whole analytical process. A Plackett-Burman experimental design was used as a multivariate strategy for the optimization of both sample preparation and preconcentration steps. The method was successfully applied to the determination of chromium and cobalt in seafood samples.

  12. [Design of Dual-Beam Spectrometer in Spectrophotometer for Colorimetry].

    PubMed

    Liu, Yi-xuan; Yan, Chang-xiang

    2015-07-01

    Spectrophotometers for colorimetry are usually composed of two independent and identical spectrometers. In order to reduce the volume of spectrophotometer for colorimetry, a design method of double-beam spectrometer is put forward. A traditional spectrometer is modified so that a new spectrometer can realize the function of double spectrometers, which is especially suitable for portable instruments. One slit is replaced by the double-slit, than two beams of spectrum can be detected. The working principle and design requirement of double-beam spectrometer are described. A spectrometer of portable spectrophotometer is designed by this method. A toroidal imaging mirror is used for the Czerny-Turner double-beam spectrometer in this paper, which can better correct astigmatism, and prevent the dual-beam spectral crosstalk. The results demonstrate that the double-beam spectrometer designed by this method meets the design specifications, with the spectral resolution less than 10 nm, the spectral length of 9.12 mm, and the volume of 57 mm x 54 mm x 23 mm, and without the dual-beam spectral overlap in the detector either. Comparing with a traditional spectrophotometer, the modified spectrophotometer uses a set of double-beam spectrometer instead of two sets of spectrometers, which can greatly reduce the volume. This design method can be specially applied in portable spectrophotometers, also can be widely applied in other double-beam spectrophotometers, which offers a new idea for the design of dual-beam spectrophotometers.

  13. White Light Pump-Probe Photothermal Mirror Spectrophotometer

    NASA Astrophysics Data System (ADS)

    Hlaing, May; Marcano, Aristides

    2016-05-01

    We develop a new kind of spectrophotometer based on the photothermal mirror effect. The absorption of a focused tunable pump light by first atomic layers of the sample's surface generates a nanometric surface distortion or bump of thermal origin. A probe beam of light of fixed wavelength and with spot dimensions much larger than the pump beam's spot is used to test this thermal distortion. Changes in the wave-front of the reflected probe beam yields changes of the diffraction pattern of the reflected beam at the far field which can be used to produce a signal proportional to the amount of released heat. Tuning of the wavelength of the pump field generates a photothermal mirror spectrum. As tunable pump source we use the light from a Xenon arc-lamp filtered using a series of interference filter. This way we generate tunable pump light in the spectral region of 370-730 nm with a HWHM of 5 nm and power density of the order of tens of microwatts per nanometer. We obtain photothermal mirror spectra of metallic surfaces and other non-transparent samples. We show that these spectra are fundamentally different from the usual reflectance spectra which measure the percentage of the total of the total energy reflected by the surface.

  14. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples.

  15. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples. PMID:25127592

  16. Imidazole-Modified Nanoporous Silica for Lead Ion Solid Phase Extraction Prior to Determination from Industrial Wastewaters by Flame Atomic Absorption Spectrometry.

    PubMed

    Behbahani, Ali; Ardjmand, Mehdi

    2015-01-01

    A new method was applied to produce modified nanoporous silica as a novel sorbent for Pb(II) ion SPE from industrial wastewater samples. In this modified method, the produced nanoporous silica has a higher functional group loading, which leads to a higher preconcentration factor as well as a lower LOD. This modified nanoporous silica was used for preconcentration prior to subsequent determination of Pb(II) ions by flame atomic absorption spectrometry. Various parameters such as the eluent, pH of the sample solution, and flow rate were optimized during this work. Also, the effect of a variety of ions on preconcentration and recovery of Pb(II) ions was investigated. The LOD, defined as five times the SD of the blank, was determined to be lower than 0.1 mg/L with an RSD of <2%. The accuracy of the method was established by analyzing standard reference materials with certified Pb concentrations. Finally, the established method was successfully applied for determination of the Pb(II) ion concentration in industrial wastewater samples.

  17. A Green Preconcentration Method for Determination of Cobalt and Lead in Fresh Surface and Waste Water Samples Prior to Flame Atomic Absorption Spectrometry

    PubMed Central

    Naeemullah; Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Khan, Sumaira; Arian, Sadaf Sadia; Brahman, Kapil Dev

    2012-01-01

    Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead (Pb) in fresh and wastewater samples. The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant. Experiments were conducted to assess the effect of different chemical variables such as pH, amounts of reagents (oxine and Triton X-114), temperature, incubation time, and sample volume. After phase separation, based on the cloud point, the surfactant-rich phase was diluted with acidic ethanol prior to its analysis by the flame atomic absorption spectrometry (FAAS). The enhancement factors 70 and 50 with detection limits of 0.26 μg L−1 and 0.44 μg L−1 were obtained for Co and Pb, respectively. In order to validate the developed method, a certified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with the certified values. The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and waste water sample. PMID:23227429

  18. Separation and Enrichment of Gold in Water, Geological and Environmental Samples by Solid Phase Extraction on Multiwalled Carbon Nanotubes Prior to its Determination by Flame Atomic Absorption Spectrometry.

    PubMed

    Duran, Ali; Tuzen, Mustafa; Soylak, Mustafa

    2015-01-01

    This study proposes the application of multi-walled carbon nanotubes as a solid sorbent for the preconcentration of gold prior to its flame atomic absorption spectrometry determination. Extraction was achieved by using a glass column (15.0 cm in length and 1.0 cm in diameter). Quantitative recoveries were obtained in the pH range of 2.5-4.0; the elution step was carried out with 5.0 ml of 1.0 mol/L HNO3 in acetone. In the ligand-free study, variables such as pH, eluent type, sample volume, flow rates, and matrix effect were examined for the optimum recovery of gold ions. The gold ions were able to be pre-concentrated by a factor of 150 and their LOD was determined to be 1.71 μg/L. In order to evaluate the accuracy of the developed method, addition-recovery tests were applied for the tap water, mineral water, and sea water samples. Gold recovery studies were implemented using a wet digestion technique for mine and soil samples taken from various media, and this method was also applied for anodic slime samples taken from the factories located in the Kayseri Industrial Zone of Turkey.

  19. Imidazole-Modified Nanoporous Silica for Lead Ion Solid Phase Extraction Prior to Determination from Industrial Wastewaters by Flame Atomic Absorption Spectrometry.

    PubMed

    Behbahani, Ali; Ardjmand, Mehdi

    2015-01-01

    A new method was applied to produce modified nanoporous silica as a novel sorbent for Pb(II) ion SPE from industrial wastewater samples. In this modified method, the produced nanoporous silica has a higher functional group loading, which leads to a higher preconcentration factor as well as a lower LOD. This modified nanoporous silica was used for preconcentration prior to subsequent determination of Pb(II) ions by flame atomic absorption spectrometry. Various parameters such as the eluent, pH of the sample solution, and flow rate were optimized during this work. Also, the effect of a variety of ions on preconcentration and recovery of Pb(II) ions was investigated. The LOD, defined as five times the SD of the blank, was determined to be lower than 0.1 mg/L with an RSD of <2%. The accuracy of the method was established by analyzing standard reference materials with certified Pb concentrations. Finally, the established method was successfully applied for determination of the Pb(II) ion concentration in industrial wastewater samples. PMID:26525261

  20. Separation and Enrichment of Gold in Water, Geological and Environmental Samples by Solid Phase Extraction on Multiwalled Carbon Nanotubes Prior to its Determination by Flame Atomic Absorption Spectrometry.

    PubMed

    Duran, Ali; Tuzen, Mustafa; Soylak, Mustafa

    2015-01-01

    This study proposes the application of multi-walled carbon nanotubes as a solid sorbent for the preconcentration of gold prior to its flame atomic absorption spectrometry determination. Extraction was achieved by using a glass column (15.0 cm in length and 1.0 cm in diameter). Quantitative recoveries were obtained in the pH range of 2.5-4.0; the elution step was carried out with 5.0 ml of 1.0 mol/L HNO3 in acetone. In the ligand-free study, variables such as pH, eluent type, sample volume, flow rates, and matrix effect were examined for the optimum recovery of gold ions. The gold ions were able to be pre-concentrated by a factor of 150 and their LOD was determined to be 1.71 μg/L. In order to evaluate the accuracy of the developed method, addition-recovery tests were applied for the tap water, mineral water, and sea water samples. Gold recovery studies were implemented using a wet digestion technique for mine and soil samples taken from various media, and this method was also applied for anodic slime samples taken from the factories located in the Kayseri Industrial Zone of Turkey. PMID:26651587

  1. A green preconcentration method for determination of cobalt and lead in fresh surface and waste water samples prior to flame atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Khan, Sumaira; Arian, Sadaf Sadia; Brahman, Kapil Dev

    2012-01-01

    Cloud point extraction (CPE) has been used for the preconcentration and simultaneous determination of cobalt (Co) and lead (Pb) in fresh and wastewater samples. The extraction of analytes from aqueous samples was performed in the presence of 8-hydroxyquinoline (oxine) as a chelating agent and Triton X-114 as a nonionic surfactant. Experiments were conducted to assess the effect of different chemical variables such as pH, amounts of reagents (oxine and Triton X-114), temperature, incubation time, and sample volume. After phase separation, based on the cloud point, the surfactant-rich phase was diluted with acidic ethanol prior to its analysis by the flame atomic absorption spectrometry (FAAS). The enhancement factors 70 and 50 with detection limits of 0.26 μg L(-1) and 0.44 μg L(-1) were obtained for Co and Pb, respectively. In order to validate the developed method, a certified reference material (SRM 1643e) was analyzed and the determined values obtained were in a good agreement with the certified values. The proposed method was applied successfully to the determination of Co and Pb in a fresh surface and waste water sample. PMID:23227429

  2. Portable Instrument to Measure CDOM Light Absorption in Aquatic Systems: WPI Success Story

    NASA Technical Reports Server (NTRS)

    2001-01-01

    World Precision Instruments, Inc. (WPI), of Sarasota, FL, in collaboration with NASA's John C. Stennis Space Center, has developed an innovative instrument to accurately measure Colored Dissolved Organic Matter (CDOM) absorption in the field. This successful collaboration has culminated in an exciting new device, called the UltraPath, now commercially available through WPI. Traditional methods of measuring absorption of dissolved materials require special handling and storage prior to measurement. Use of laboratory spectrophotometers as the measuring devices have proven time consuming, cumbersome, and delicate to handle. The UltraPath provides a low-cost, highly sensitive, rugged, portable system that is capable of high sensitivity measurements in widely divergent waters.

  3. Development of an ultra-compact mid-infrared attenuated total reflectance spectrophotometer

    NASA Astrophysics Data System (ADS)

    Kim, Dong Soo; Lee, Tae-Ro; Yoon, Gilwon

    2014-07-01

    Mid-infrared spectroscopy has been an important tool widely used for qualitative analysis in various fields. However, portable or personal use is size and cost prohibitive for either Fourier transform infrared or attenuated total reflectance (ATR) spectrophotometers. In this study, we developed an ultra-compact ATR spectrophotometer whose frequency band was 5.5-11.0 μm. We used miniature components, such as a light source fabricated by semiconductor technology, a linear variable filter, and a pyro-electric array detector. There were no moving parts. Optimal design based on two light sources, a zippered configuration of the array detector and ATR optics could produce absorption spectra that might be used for qualitative analysis. A microprocessor synchronized the pulsed light sources and detector, and all the signals were processed digitally. The size was 13.5×8.5×3.5 cm3 and the weight was 300 grams. Due to its low cost, our spectrophotometer can replace many online monitoring devices. Another application could be for a u-healthcare system installed in the bathroom or attached to a smartphone for monitoring substances in body fluids.

  4. Metal interferences and their removal prior to the determination of As(T) and As(III) in acid mine waters by hydride generation atomic absorption spectrometry

    USGS Publications Warehouse

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ball, James W.

    2003-01-01

    Hydride generation atomic absorption spectrometry (HGAAS) is a sensitive and selective method for the determination of total arsenic (arsenic(III) plus arsenic(V)) and arsenic(III); however, it is subject to metal interferences for acid mine waters. Sodium borohydride is used to produce arsine gas, but high metal concentrations can suppress arsine production. This report investigates interferences of sixteen metal species including aluminum, antimony(III), antimony(V), cadmium, chromium(III), chromium(IV), cobalt, copper(II), iron(III), iron(II), lead, manganese, nickel, selenium(IV), selenium(VI), and zinc ranging in concentration from 0 to 1,000 milligrams per liter and offers a method for removing interfering metal cations with cation exchange resin. The degree of interference for each metal without cation-exchange on the determination of total arsenic and arsenic(III) was evaluated by spiking synthetic samples containing arsenic(III) and arsenic(V) with the potential interfering metal. Total arsenic recoveries ranged from 92 to 102 percent for all metals tested except antimony(III) and antimony(V) which suppressed arsine formation when the antimony(III)/total arsenic molar ratio exceeded 4 or the antimony(V)/total arsenic molar ratio exceeded 2. Arsenic(III) recoveries for samples spiked with aluminum, chromium(III), cobalt, iron(II), lead, manganese, nickel, selenium(VI), and zinc ranged from 84 to 107 percent over the entire concentration range tested. Low arsenic(III) recoveries occurred when the molar ratios of metals to arsenic(III) were copper greater than 120, iron(III) greater than 70, chromium(VI) greater than 2, cadmium greater than 800, antimony(III) greater than 3, antimony(V) greater than 12, or selenium(IV) greater than 1. Low recoveries result when interfering metals compete for available sodium borohydride, causing incomplete arsine production, or when the interfering metal oxidizes arsenic(III). Separation of interfering metal cations using

  5. Correction of wavelength errors in a digitally recording spectrophotometer.

    PubMed

    Robertson, A R; Budde, W; McNeely, F T

    1973-12-01

    A simple circuit is described that enables known wavelength errors of a digitally recording spectrophotometer to be corrected. The circuit delays the signal that triggers the recording system. The length of the delay is varied as a function of wavelength to correct for the errors. Significant improvement can be obtained in the measurement of CIE tristimulus values.

  6. Dobson spectrophotometer ozone measurements during international ozone rocketsonde intercomparison

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.

    1980-01-01

    Measurements of the total ozone content of the atmosphere, made with seven ground based instruments at a site near Wallops Island, Virginia, are discussed in terms for serving as control values with which the rocketborne sensor data products can be compared. These products are profiles of O3 concentration with altitude. By integrating over the range of altitudes from the surface to the rocket apogee and by appropriately estimating the residual ozone amount from apogee to the top of the atmosphere, a total ozone amount can be computed from the profiles that can be directly compared with the ground based instrumentation results. Dobson spectrophotometers were used for two of the ground-based instruments. Preliminary data collected during the IORI from Dobson spectrophotometers 72 and 38 are presented. The agreement between the two and the variability of total ozone overburden through the experiment period are discussed.

  7. Non-focusing optics spectrophotometer, and methods of use

    DOEpatents

    Kramer, David M.; Sacksteder, Colette A.

    2004-11-02

    In one aspect, the present invention provides kinetic spectrophotometers that each comprise: (a) a light source; and (b) a compound parabolic concentrator disposed to receive light from the light source and configured to (1) intensify and diffuse the light received from the light source, and (2) direct the intensified and diffused light onto a sample. In other aspects, the present invention provides methods for measuring a photosynthetic parameter, the methods comprising the steps of: (a) illuminating a plant leaf until steady-state photosynthesis is achieved; (b) subjecting the illuminated plant leaf to a period of darkness; (c) using a kinetic spectrophotometer of the invention to collect spectral data from the plant leaf treated in accordance with steps (a) and (b); and (d) determining a value for a photosynthetic parameter from the spectral data.

  8. How Students Use Scientific Instruments To Create Understanding: CCD Spectrophotometers

    NASA Astrophysics Data System (ADS)

    Malina, Eric G.; Nakhleh, Mary B.

    2003-06-01

    We investigated how upper-division college students interacted with a CCD spectrophotometer to identify the characteristics of this instrument that influenced students‘ construction of scientific understanding. We specifically wanted to understand the mechanisms by which scientific instruments influence student learning. The ideas of distributed cognition and the theory of affordances were used as a framework to identify the affordances of the CCD spectrophotometer that affected learning. We found the primary affordances of the spectrophotometer were related to the graphical display of data. Students were able to use this feature in order to: (1) interpret their data, (2) discover unexpected results, (3) confirm the validity of their data, (4) make predictions about their solutions, and (5) check for error. We found other affordances that fit into four general areas: time, error, ease of use, and other physical affordances. Overall, we found that experimental designs and objectives influence the affordances that students perceive in instruments. Therefore, instructors must be cognizant of their objectives for instrument use in a laboratory setting and choose instruments and procedures that are consistent with those objectives.

  9. 21 CFR 862.2300 - Colorimeter, photometer, or spectrophotometer for clinical use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Colorimeter, photometer, or spectrophotometer for... Clinical Laboratory Instruments § 862.2300 Colorimeter, photometer, or spectrophotometer for clinical use. (a) Identification. A colorimeter, a photometer, or a spectrophotometer for clinical use is...

  10. 21 CFR 862.2300 - Colorimeter, photometer, or spectrophotometer for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Colorimeter, photometer, or spectrophotometer for... Clinical Laboratory Instruments § 862.2300 Colorimeter, photometer, or spectrophotometer for clinical use. (a) Identification. A colorimeter, a photometer, or a spectrophotometer for clinical use is...

  11. Ultraviolet spectrophotometer for measuring columnar atmospheric ozone from aircraft.

    PubMed

    Hanser, F A; Sellers, B; Briehl, D C

    1978-05-15

    An ultraviolet spectrophotometer (UVS) to measure downward solar fluxes from an aircraft or other high altitude platform is described. The UVS uses an ultraviolet diffuser to obtain large angular response with no aiming requirement, a twelve-position filter wheel with narrow (2-nm) and broad (20-nm) bandpass filters, and an ultraviolet photodiode. The columnar atmospheric ozone above the UVS (aircraft) is calculated from the ratios of the measured ultraviolet fluxes. Comparison with some Dobson station measurements gives agreement to 2%. Some UVS measured ozone profiles over the Pacific Ocean for November 1976 are shown to illustrate the instrument's performance.

  12. UV-observations with a Brewer spectrophotometer at Hohenpeissenberg

    NASA Technical Reports Server (NTRS)

    Vandersee, Winfried; Koehler, U.

    1994-01-01

    Regular spectral UV-B measurements with a Brewer spectrophotometer have been performed at Hohenpeissenberg since 1990. Intercomparison of the Brewer instrument with other UV-B monitoring devices have shown agreement to within plus or minus 10 percent. Comparisons of UV-B spectra measured on fair weather days reveal the well known increasing influence of ozone on UV-B irradiance with decreasing wavelengths. The integral amplification factor the erythemal irradiance reaches values up to 2.8, which can be diminished by increasing turbidity. The influence of cirrus cloud on the UV-B is also shown.

  13. Simple LED spectrophotometer for analysis of color information.

    PubMed

    Kim, Ji-Sun; Kim, A-Hee; Oh, Han-Byeol; Goh, Bong-Jun; Lee, Eun-Suk; Kim, Jun-Sik; Jung, Gu-In; Baek, Jin-Young; Jun, Jae-Hoon

    2015-01-01

    A spectrophotometer is the basic measuring equipment essential to most research activity fields requiring samples to be measured, such as physics, biotechnology and food engineering. This paper proposes a system that is able to detect sample concentration and color information by using LED and color sensor. Purity and wavelength information can be detected by CIE diagram, and the concentration can be estimated with purity information. This method is more economical and efficient than existing spectrophotometry, and can also be used by ordinary persons. This contribution is applicable to a number of fields because it can be used as a colorimeter to detect the wavelength and purity of samples.

  14. A dispersive liquid--liquid microextraction methodology for copper (II) in environmental samples prior to determination using microsample injection flame atomic absorption spectrometry.

    PubMed

    Alothman, Zeid A; Habila, Mohamed; Yilmaz, Erkan; Soylak, Mustafa

    2013-01-01

    A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples. PMID:24645524

  15. Ionic liquid-linked dual magnetic microextraction of lead(II) from environmental samples prior to its micro-sampling flame atomic absorption spectrometric determination.

    PubMed

    Yilmaz, Erkan; Soylak, Mustafa

    2013-11-15

    A novel and rapid microextraction approach termed as ionic liquid-linked dual magnetic microextraction (IL-DMME), was developed for the atomic absorption spectrometric determination of lead. The developed method based on a combination of dispersive liquid-liquid microextraction (DLLME) and dispersive micro solid-phase extraction (D-μ-SPE). In the first DLLME step, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was selected to extract the lead-pyrrolidine-dithiocarbamate (Pb-PDC) complex from sample solution by the assistance of vortex agitator. After the first step, fifty milligrams of Fe3O4 magnetic nanoparticles (MNPs) were added to extraction of the ionic liquid and Pb-PDC complex in aqueous solution. The effective factors in proposed IL-DMME procedure, including volume of 1-butyl-3-methylimidazolium hexafluorophosphate, amount of Fe3O4 magnetic nanoparticles, vortex time, amount of ammonium pyrrolidinedithiocarbamate, sample volume and matrix effect were optimized in details. Under the optimal conditions, the method present has low detection limit (0.57 μg L(-1)), high preconcentration factor (160) and good repeatability (<7.5%, n=10). The accuracy of the developed method was evaluated by the analysis of the certified reference materials and addition-recovery tests. The method was successfully applied to the determination of lead in water, plant and hair samples.

  16. Ultrasound-assisted emulsification microextraction based on solidification floating organic drop trace amounts of manganese prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Mohadesi, Alireza; Falahnejad, Masoumeh

    2012-01-01

    In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn(+2) at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50-10.0 ng mL(-1) with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL(-1) was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

  17. Ultrasound-assisted emulsification solidified floating organic drops microextraction of ultra trace amount of Te (IV) prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Fathirad, Fariba; Afzali, Daryoush; Mostafavi, Ali; Ghanbarian, Maryam

    2012-01-15

    In the present study, a new, simple and efficient method for the preconcentration of ultra trace amounts of Te (IV) is developed using ultrasound-assisted emulsification solidified floating organic drops microextraction (USAE-SFODME) before graphite furnace atomic absorption spectrometry determination. In this method, tellurium is extracted into the fine droplets of 1-undecanol after chelate formation with the water soluble ligand, ammonium pyrrolidinedithiocarbamate (APDC). Several factors such as pH, chelating agent amount, type and volume of the extracting solvent, sonication and centrifuging time that influence the extraction and complex formation are optimized. Under the optimum conditions, the calibration graph is linear in the range of 0.01-0.24ngmL(-1) of tellurium in the original solution, with limit of detection of 0.003ngmL(-1). The relative standard deviation (RSD) for seven replicated determinations of tellurium ion at 0.08ngmL(-1) concentration level is calculated as 3.4%. The proposed method was successfully applied to the determination of Te (IV) in a standard soil and several water samples. PMID:22265571

  18. Preparation of modified magnetic nanoparticles as a sorbent for the preconcentration and determination of cadmium ions in food and environmental water samples prior to flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Mirabi, Ali; Dalirandeh, Zeinab; Rad, Ali Shokuhi

    2015-05-01

    A new method has been developed for the separation/preconcentration of trace level cadmium ions using diphenyl carbazone/sodium dodecyl sulfate immobilized on magnetic nanoparticle Fe3O4 as a new sorbent SPE and their determination by flame atomic absorption spectrometry (FAAS). Synthesized nanoparticle was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). Various influencing parameters on the separation and preconcentration of trace level cadmium ions such as, pH value, amount of nanoparticles, amount of diphenyl carbazone, condition of eluting solution, the effects of matrix ions were examined. The cadmium ions can be eluted from the modified magnetic nanoparticle using 1 mol L-1 HCl as a desorption reagent. The detection limit of this method for cadmium was 3.71 ng ml-1 and the R.S.D. was 0.503% (n=6). The advantages of this new method include rapidity, easy preparation of sorbents and a high concentration factor. The proposed method has been applied to the determination of Cd ions at trace levels in real samples such as, green tea, rice, tobacco, carrot, lettuce, ginseng, spice, tap water, river water, sea water with satisfactory results.

  19. Magnetic stirrer induced dispersive ionic-liquid microextraction for the determination of vanadium in water and food samples prior to graphite furnace atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa

    2015-04-01

    A new dispersive liquid-liquid microextraction, magnetic stirrer induced dispersive ionic-liquid microextraction (MS-IL-DLLME) was developed to quantify the trace level of vanadium in real water and food samples by graphite furnace atomic absorption spectrometry (GFAAS). In this extraction method magnetic stirrer was applied to obtained a dispersive medium of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] in aqueous solution of (real water samples and digested food samples) to increase phase transfer ratio, which significantly enhance the recovery of vanadium - 4-(2-pyridylazo) resorcinol (PAR) chelate. Variables having vital role on desired microextraction methods were optimised to obtain the maximum recovery of study analyte. Under the optimised experimental variables, enhancement factor (EF) and limit of detection (LOD) were achieved to be 125 and 18 ng L(-1), respectively. Validity and accuracy of the desired method was checked by analysis of certified reference materials (SLRS-4 Riverine water and NIST SRM 1515 Apple leaves). The relative standard deviation (RSD) for 10 replicate determinations at 0.5 μg L(-1) of vanadium level was found to be <5.0%. This method was successfully applied to real water and acid digested food samples.

  20. Simultaneous coprecipitation of lead, cobalt, copper, cadmium, iron and nickel in food samples with zirconium(IV) hydroxide prior to their flame atomic absorption spectrometric determination.

    PubMed

    Citak, Demirhan; Tuzen, Mustafa; Soylak, Mustafa

    2009-09-01

    A simple and new coprecipitation procedure is developed for the determination of trace quantities of heavy metals (lead, cobalt, copper, cadmium, iron and nickel) in natural water and food samples. Analyte ions were coprecipitated by using zirconium(IV) hydroxide. The determination of metal levels was performed by flame atomic absorption spectrometry (FAAS). The influences of analytical parameters including pH, amount of zirconium(IV), sample volume, etc. were investigated on the recoveries of analyte ions. The effects of possible matrix ions were also examined. The recoveries of the analyte ions were in the range of 95-100%. Preconcentration factor was calculated as 25. The detection limits for the analyte ions based on 3 sigma (n=21) were in the range of 0.27-2.50 microgL(-1). Relative standard deviation was found to be lower than 8%. The validation of the presented coprecipitation procedure was performed by the analysis certified reference materials (GBW 07605 Tea and LGC 6010 Hard drinking water). The procedure was successfully applied to natural waters and food samples like coffee, fish, tobacco, black and green tea. PMID:19539005

  1. Green Preconcentration of Trace Amounts of Copper from Water and Food Samples onto Novel Organo-Nanoclay Prior to Flame Atomic Absorption Spectrometry.

    PubMed

    Beyki, Mostafa Hossein; Shemirani, Farzaneh; Khani, Rouhollah

    2014-01-01

    In this work, the nanoclay was intercalated with acyclovir (9-[(2-hydroxyethoxy) methyl] guanine), the toxicity of which to mammalian cells is very low. We used no organic solvents for preparation of modified clay and desorption of Cu ions from the sorbent. Batch and column methods were used, and sorption of Cu was quantitative (>98%) in the pH range of 7.5 to 10.0. Quantitative desorption occurred with 5.0 mL of 3.0 M HCl, and the amount of Cu(II) was measured by using flame atomic absorption spectrometry. In the initial solution the linear dynamic range and the LOD were 3.0-1000.0 and 0.58 μg/L, respectively. With 500.0 mL of sample, an enrichment factor of 100 was obtained. The RSD was 2.0% (n = 8, concentration = 0.5 mg/L), and the maximum capacity of the sorbent was 45.0 mg/g. The influence of experimental parameters including sample pH, ionic strength, type and volume of the eluent, and interference of some ions on the recoveries of Cu was investigated. The proposed method using a new and easier prepared solid sorbent was applied to the determination of Cu in different real samples with satisfactory results. PMID:25902995

  2. Ionic liquid-linked dual magnetic microextraction of lead(II) from environmental samples prior to its micro-sampling flame atomic absorption spectrometric determination.

    PubMed

    Yilmaz, Erkan; Soylak, Mustafa

    2013-11-15

    A novel and rapid microextraction approach termed as ionic liquid-linked dual magnetic microextraction (IL-DMME), was developed for the atomic absorption spectrometric determination of lead. The developed method based on a combination of dispersive liquid-liquid microextraction (DLLME) and dispersive micro solid-phase extraction (D-μ-SPE). In the first DLLME step, 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6], was selected to extract the lead-pyrrolidine-dithiocarbamate (Pb-PDC) complex from sample solution by the assistance of vortex agitator. After the first step, fifty milligrams of Fe3O4 magnetic nanoparticles (MNPs) were added to extraction of the ionic liquid and Pb-PDC complex in aqueous solution. The effective factors in proposed IL-DMME procedure, including volume of 1-butyl-3-methylimidazolium hexafluorophosphate, amount of Fe3O4 magnetic nanoparticles, vortex time, amount of ammonium pyrrolidinedithiocarbamate, sample volume and matrix effect were optimized in details. Under the optimal conditions, the method present has low detection limit (0.57 μg L(-1)), high preconcentration factor (160) and good repeatability (<7.5%, n=10). The accuracy of the developed method was evaluated by the analysis of the certified reference materials and addition-recovery tests. The method was successfully applied to the determination of lead in water, plant and hair samples. PMID:24148489

  3. Does the prior application of the field kit bullet hole testing kit 3 on a suspected bullet hole bias the analysis of atomic absorption spectrophotometry?

    PubMed

    Seltenhammer, Monika H; Fitzl, Christine; Wieser, Ingo; Binder, Reinhard; Paula, Pia; Risser, Daniele U

    2014-09-01

    Forensic ballistics is the study of bullet trajectory and consists of determining gunshot residue (GSR) to identify bullet holes. Among several highly sensitive methods, atomic absorption spectrophotometry (AAS) is employed to analyze GSR in the laboratory. However, it is sometimes necessary to identify bullet holes immediately at a crime scene. The purpose of this examination was to determine whether the use of the field test Bullet Hole Testing Kit 3 (BTK3) on a suspected bullet hole would influence the outcome of AAS-analysis: Three commonly encountered firearms (Glock17, Tokarev, and Colt) were fired at skin, wood, and cloth. AAS-analysis was performed with and without previous BTK3 application. The results clearly indicate that there is no significant interaction on the grounds of BTK3 use (BTK3 vs. no-BTK3 [kit_nokit] [Pb: p = 0.1309; Sb: p = 0.9111], material*kit_nokit [Pb: p = 0.5960; Sb: p = 0.9930], distance*kit_nokit [Pb: p = 0.4014; Sb: p = 0.9184], and firearm type*kit_nokit [Pb: p = 0.9662; Sb: p = 0.9885]); hence, applying this field kit does not falsify later AAS outcomes.

  4. Ultrasound-assisted emulsification solidified floating organic drops microextraction of ultra trace amount of Te (IV) prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Fathirad, Fariba; Afzali, Daryoush; Mostafavi, Ali; Ghanbarian, Maryam

    2012-01-15

    In the present study, a new, simple and efficient method for the preconcentration of ultra trace amounts of Te (IV) is developed using ultrasound-assisted emulsification solidified floating organic drops microextraction (USAE-SFODME) before graphite furnace atomic absorption spectrometry determination. In this method, tellurium is extracted into the fine droplets of 1-undecanol after chelate formation with the water soluble ligand, ammonium pyrrolidinedithiocarbamate (APDC). Several factors such as pH, chelating agent amount, type and volume of the extracting solvent, sonication and centrifuging time that influence the extraction and complex formation are optimized. Under the optimum conditions, the calibration graph is linear in the range of 0.01-0.24ngmL(-1) of tellurium in the original solution, with limit of detection of 0.003ngmL(-1). The relative standard deviation (RSD) for seven replicated determinations of tellurium ion at 0.08ngmL(-1) concentration level is calculated as 3.4%. The proposed method was successfully applied to the determination of Te (IV) in a standard soil and several water samples.

  5. Separation and preconcentration of trace amounts of gold(III) ions using modified multiwalled carbon nanotube sorbent prior to flame atomic absorption spectrometry determination.

    PubMed

    Afzali, Daryoush; Ghaseminezhad, Sima; Taher, Mohammad Ali

    2010-01-01

    Multiwalled carbon nanotubes are attractive as sorbents for SPE because they can be used for enrichment of organic compounds and metal ions at trace levels. In this study, multiwalled carbon nanotubes were oxidized with concentrated HNO3, and then the oxidized multiwalled carbon nanotubes were modified with 5-(4'-dimethylamino-benzyliden)-rhodanine. The modified multiwalled carbon nanotubes were used as a solid sorbent for separation and preconcentration of trace amounts of Au(III) ions. The sorption of Au(III) ions was quantitative in the pH range of 2.0-5.0, whereas quantitative desorption occurred instantaneously with 5.0 mL 2.0 M Na2S2O3. The eluted solution was aspirated directly into the flame for atomic absorption spectrometry. The proposed method resulted in an enrichment factor of 94. The RSD of the method was +/- 1.11% (n=10, 2.0 microg/mL) and the LOD was 0.15 ng/mL. The calibration curve for Au(III) was linear between 0.53 ng/mL and 36.0 microg/mL in the initial solution, with an R2 value of 0.9999. The sorbent capacity of the modified multiwalled carbon nanotubes was 7.3 mg Au(III)/g sorbent. The influences of the experimental parameters, including sample pH, sample flow rate, eluent volume and flow rate, sample volume, and interference of some ions on the recoveries of the Au ions, were investigated. The proposed method was applied for preconcentration and determination of Au in different samples.

  6. In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry.

    PubMed

    Shokri, Masood; Beiraghi, Asadollah; Seidi, Shahram

    2015-08-19

    For the first time, a simple and efficient in situ emulsification microextraction method using a dicationic ionic liquid followed by magnetic assisted physisorption was presented to determine trace amounts of lead. In this method, 400 μL of 1.0 mol L(-1) lithium bis (trifluoromethylsulfonyl) imide aqueous solution, Li[NTf2], was added into the sample solution containing 100 μL of 1.0 mol L(-1) 1,3-(propyl-1,3-diyl) bis (3-methylimidazolium) chloride, [pbmim]Cl2, to form a water immiscible ionic liquid, [pbmim][NTf2]2. This new in situ formed dicationic ionic liquid was applied as the acceptor phase to extract the lead-ammonium pyrrolidinedithiocarbamate (Pb-APDC) complexes from the sample solution. Subsequently, 30 mg of Fe3O4 magnetic nanoparticles (MNPs) were added into the sample solution to collect the fine droplets of [pbmim][NTf2]2, physisorptively. Finally, MNPs were eluted by acetonitrile, separated by an external magnetic field and the obtained eluent was subjected to micro-sampling flame atomic absorption spectrometry (FAAS) for further analysis. Comparing with other microextraction methods, no special devices and centrifugation step are required. Parameters influencing the extraction efficiency such as extraction time, pH, concentration of chelating agent, amount of MNPs and coexisting interferences were studied. Under the optimized conditions, this method showed high extraction recovery of 93% with low LOD of 0.7 μg L(-1). Good linearity was obtained in the range of 2.5-150 μg L(-1) with determination coefficient (r(2)) of 0.9921. Relative standard deviation (RSD%) for seven repeated measurements at the concentration of 10 μg L(-1) was 4.1%. Finally, this method was successfully applied for determination of lead in some water and plant samples. PMID:26343434

  7. Results of international Dobson spectrophotometer calibrations at Arosa, Switzerland, 1990

    NASA Technical Reports Server (NTRS)

    Grass, R. D.; Komhyr, W. D.; Koenig, G. L.; Evans, R. D.

    1994-01-01

    An international comparison of Dobson ozone spectrophotometers, organized and partially funded by the World Meteorological Organization (WMO), was held at the Lichtklimatisches Observatorium (LKO) in Arosa, Switzerland, July-August 1990. Countries participating with a total of 18 Dobson instruments were Belgium, Czechoslovakia, Denmark, Germany, Greece, Hungary, Iceland, Norway, Poland, Portugal, Rumania, Spain, Switzerland, the United Kingdom, the United States, and the United Soviet Socialist Republics. The reference standard instrument for the comparison was U.S.A. Secondary Standard Dobson Spectrophotometer 65 maintained by the NOAA Climate and Monitoring and Diagnostics Laboratory, Boulder, Colorado. The mean difference in ozone obtained with the Dobson instruments relative to Dobson instrument 65, calculated from ADDSGQP observations in the air mass range 1.15-3.2, was minus 1.0 plus or minus 1.2 (1 sigma) percent. The WMO Standard Brewer Spectrometer 39 also participated. In the mean, the Brewer instrument measured 0.6 plus or minus 0.2 (1 sigma) percent more ozone than did Dobson instrument 65. Results are presented, also, of ozone vertical profile measurements made with the Dobson instruments, two Brewer spectrometers, a LIDAR, a balloon ozonesonde flown from Hohenpeissenberg, Germany, and balloon ozonesondes flown from Payerne, Switzerland.

  8. Microcontroller based spectrophotometer using compact disc as diffraction grid

    NASA Astrophysics Data System (ADS)

    Bano, Saleha; Altaf, Talat; Akbar, Sunila

    2010-12-01

    This paper describes the design and implementation of a portable, inexpensive and cost effective spectrophotometer. The device combines the use of compact disc (CD) media as diffraction grid and 60 watt bulb as a light source. Moreover it employs a moving slit along with stepper motor for obtaining a monochromatic light, photocell with spectral sensitivity in visible region to determine the intensity of light and an amplifier with a very high gain as well as an advanced virtual RISC (AVR) microcontroller ATmega32 as a control unit. The device was successfully applied to determine the absorbance and transmittance of KMnO4 and the unknown concentration of KMnO4 with the help of calibration curve. For comparison purpose a commercial spectrophotometer was used. There are not significant differences between the absorbance and transmittance values estimated by the two instruments. Furthermore, good results are obtained at all visible wavelengths of light. Therefore, the designed instrument offers an economically feasible alternative for spectrophotometric sample analysis in small routine, research and teaching laboratories, because the components used in the designing of the device are cheap and of easy acquisition.

  9. Silica gel modified with N-(3-propyl)-O-phenylenediamine: functionalization, metal sorption equilibrium studies and application to metal enrichment prior to determination by flame atomic absorption spectrometry.

    PubMed

    Akl, Magda Ali Abd-elAziz; Kenawy, Ibraheim Mohamed; Lasheen, Rabab Ramadan

    2005-08-01

    The use of the chemically modified silica gel N-(3-propyl)-O-phenylenediamine (SiG-NPPDA) adsorbent, for the preconcentration and separation of trace heavy metals, was described. SiG-NPPDA sorbs quantitatively (90-100% recovery) trace amounts of nine heavy metals, viz., Cd(II), Zn(II), Fe(III), Cu(II), Pb(II), Mn(II), Cr(III), Co(II) and Ni(II) at pH 7-8. The sorption capacity varies from 350 to 450 micromol g(-1). Desorption was found to be quantitative with 1-2 M HNO3 or 0.05 M Na2EDTA. The distribution coefficient, Kd and the percentage concentration of the investigated metal ions on the adsorbent at equilibrium, C(M,eqm)% (Recovery, R%), were studied as a function of experimental parameters. The logarithmic values of the distribution coefficient, log Kd, ranges between 4.0 and 6.4. Some foreign ions caused little interference in the preconcentration and determination of the investigated nine metals by flame atomic absorption spectrometry (AAS). The adsorbent and its formed metal chelates were characterized by IR (absorbance and/or reflectance), potentiometric titrations and thermogravimetric analysis (TGA and DTG). The mode of chelation between the SiG-NPPDA adsorbent and the investigated metal ions is proposed to be due to the reaction of the investigated metal ions with the two nitrogen atoms of the SiG-NPPDA adsorbent. The present adsorbent coupled with flame AAS has been used to enrich and determine the nine metal ions in natural aqueous systems and in certified reference materials (RSD < or = 5%). The copper, iron, manganese and zinc present in some pharmaceutical vitamin samples were also preconcentrated on SiG-NPPDA adsorbent and determined by flame AAS (RSD < or = 4.2%). Nanogram concentrations (0.07-0.14 ng ml(-1)) of Cd(II), Zn(II), Fe(III), Pb(II), Cr(III), Mn(II), Cu(II), Co(II) and Ni(II) can be determined reliably with a preconcentration factor of 100.

  10. Estimation of total alkaloid in Chitrakadivati by UV-Spectrophotometer

    PubMed Central

    Ajanal, Manjunath; Gundkalle, Mahadev B.; Nayak, Shradda U.

    2012-01-01

    Background: Herbal formulation standardization by adopting newer technique is need of the hour in the field of Ayurvedic pharmaceutical industry. As very few reports exist. These kind of studies would certainly widen the herbal research area. Chitrakadivati is one such popular herbal formulation used in Ayurveda. Many of its ingredients are known for presence of alkaloids. Methodology: Presence of alkaloid was tested qualitatively by Dragondroff's method then subjected to quantitative estimation by UV-Spectrophotometer. This method is based on the reaction between alkaloid and bromocresol green (BCG). Results and Conclusion: Study discloses that out of 16 ingredients, 9 contain alkaloid. Chitrakadivati has shown 0.16% of concentration of alkaloid and which is significantly higher than it's individual ingredients. PMID:23661869

  11. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630–720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  12. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630-720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  13. 21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... elements and metals (e.g., lead and mercury) in human specimens. The metal elements are identified according to the wavelength and intensity of the light that is absorbed when the specimen is converted...

  14. 21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... elements and metals (e.g., lead and mercury) in human specimens. The metal elements are identified according to the wavelength and intensity of the light that is absorbed when the specimen is converted...

  15. The Spectrophotometer II: A Module on the Spectral Properties of Light. Tech Physics Series.

    ERIC Educational Resources Information Center

    Frank, Nathaniel; And Others

    This module is designed to give the learner an understanding of the nature of light and how its properties are used in the design of spectrophotometers. Problems promote the use of spectrophotometers in qualitative analysis, the optical elements used in a monochromator, and the physical properties of the prism and the diffraction grating. Other…

  16. An automated optical wedge calibrator for Dobson ozone spectrophotometers

    NASA Technical Reports Server (NTRS)

    Evans, R. D.; Komhyr, W. D.; Grass, R. D.

    1994-01-01

    The Dobson ozone spectrophotometer measures the difference of intensity between selected wavelengths in the ultraviolet. The method uses an optical attenuator (the 'Wedge') in this measurement. The knowledge of the relationship of the wedge position to the attenuation is critical to the correct calculation of ozone from the measurement. The procedure to determine this relationship is time-consuming, and requires a highly skilled person to perform it correctly. The relationship has been found to change with time. For reliable ozone values, the procedure should be done on a Dobson instrument at regular intervals. Due to the skill and time necessary to perform this procedure, many instruments have gone as long as 15 years between procedures. This article describes an apparatus that performs the procedure under computer control, and is adaptable to the majority of existing Dobson instruments. Part of the apparatus is usable for normal operation of the Dobson instrument, and would allow computer collection of the data and real-time ozone measurements.

  17. Design of a novel spectrophotometer for water quality monitor based on holography concave grating and CCD

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Zeng, Lvming; Huang, Zhen

    2011-11-01

    With the rapid development of the society and living standard, the water resources have been polluted more and more seriously, which is threatening the health of people and producing of the industry and agriculture. To protect the sustainable water resource, the monitoring of the water quality became an urgent task. There are some methods used to monitor the water quality, including the liquid chromatograph(LC), electrolysis method, electrochemical method, colorimetry method, atomic absorption spectrometric method, etc. But some drawbacks are existed in these methods. So, a fluorescence spectrophotometry method is adopted into this paper. And a novel water quality monitor(WQM) is designed. Meanwhile, in order to improve the spectral resolution and prevision, an improved spectrophotometer(SPM) based on holography concave (HC)grating is designed. In addition, the linear CCD with combined data acquisition (DAQ) card is used as the spectral detection system and virtual instrument(VI) technology based on LabVIEW is used to control the spectral acquisition and analysis. Experimental results show that the performances of the novel SPM for WQM are improved, its resolution can reach 2nm, the stray-light is less and the checking prevision of this WQM is higher than others. Therefore, the novel SPM for WQM has the potential value in the water quality monitoring and biochemical application.

  18. Design of a novel spectrophotometer for water quality monitor based on holography concave grating and CCD

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Zeng, Lvming; Huang, Zhen

    2012-01-01

    With the rapid development of the society and living standard, the water resources have been polluted more and more seriously, which is threatening the health of people and producing of the industry and agriculture. To protect the sustainable water resource, the monitoring of the water quality became an urgent task. There are some methods used to monitor the water quality, including the liquid chromatograph(LC), electrolysis method, electrochemical method, colorimetry method, atomic absorption spectrometric method, etc. But some drawbacks are existed in these methods. So, a fluorescence spectrophotometry method is adopted into this paper. And a novel water quality monitor(WQM) is designed. Meanwhile, in order to improve the spectral resolution and prevision, an improved spectrophotometer(SPM) based on holography concave (HC)grating is designed. In addition, the linear CCD with combined data acquisition (DAQ) card is used as the spectral detection system and virtual instrument(VI) technology based on LabVIEW is used to control the spectral acquisition and analysis. Experimental results show that the performances of the novel SPM for WQM are improved, its resolution can reach 2nm, the stray-light is less and the checking prevision of this WQM is higher than others. Therefore, the novel SPM for WQM has the potential value in the water quality monitoring and biochemical application.

  19. Development of a new green non-dispersive ionic liquid microextraction method in a narrow glass column for determination of cadmium prior to couple with graphite furnace atomic absorption spectrometry.

    PubMed

    Naeemullah; Kazi, Tasneem Gul; Tuzen, Mustafa; Shah, Faheem; Afridi, Hassan Imran; Citak, Demirhan

    2014-02-17

    Easy and innovative non-dispersive ionic liquid based microextraction (NDILME) has been developed for preconcentration of trace level of cadmium (Cd) in aqueous real surface water samples prior to couple with graphite furnace atomic absorption spectrometry (GFAAS). A 200 cm long narrow glass column containing aqueous solution of standard/sample was used to increase phase transfer ratio by providing more contact area between two medium (aqueous and extractive), which drastically improve the recoveries of labile hydrophobic chelate of Cd ammonium pyrrolidinedithiocarbamate (APDC), into ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6]. Different aspect of the desire method have been investigated and optimized. Under the optimized key experimental variables, limit of detection (LOD) and enhancement factor (EF) were achieved to be 0.5 ng L(-1) and 150, respectively. Reliability of the model method was checked by relative standard deviation (%RSD), which was found to be <5%. Validity and accuracy of the developed method was checked by analysis of certified reference water samples (SLRS-4 Riverine water) using standard addition method. Application of the model method was productively performed by analysis of Cd in real surface water samples (tap and sea).

  20. Optical characterization of ex-vivo axillary lymph nodes of breast-cancer patients using a custom-built spectrophotometer

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Saegusa-Beecroft, Emi; Mamou, Jonathan; Chitnis, Parag V.; Machi, Junji; Feleppa, Ernest J.

    2014-03-01

    Quantitative photoacoustics is emerging as a new hybrid modality to investigate diseases and cells in human pathology and cytology studies. Optical absorption of light is the predominant mechanism behind the photoacoustic effect. Therefore, a need exits to characterize the optical properties of specimens and to identify the relevant operating wavelengths for photoacoustic imaging. We have developed a custom low-cost spectrophotometer to measure the optical properties of human axillary lymph nodes dissected for breast-cancer staging. Optical extinction curves of positive and negative nodes were determined in the spectral range of 400 to 1000 nm. We have developed a model to estimate tissue optical properties, taking into account the role of fat and saline. Our results enabled us to select the optimal optical wavelengths for maximizing the imaging contrast between metastatic and noncancerous tissue in axillary lymph nodes.

  1. 2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. ...

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

    2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. AIR FILTERS AND SWIPES ARE DISSOLVED WITH ACIDS AND THE REMAINING RESIDUES ARE SUSPENDED IN NITRIC ACID SOLUTION. THE SOLUTION IS PROCESSED THROUGH THE ATOMIC ABSORPTION SPECTROPHOTOMETER TO DETECT THE PRESENCE AND LEVELS OF BERYLLIUM. - Rocky Flats Plant, Health Physics Laboratory, On Central Avenue between Third & Fourth Streets, Golden, Jefferson County, CO

  2. The Erlangen micro-lightguide spectrophotometer EMPHO I.

    PubMed

    Frank, K H; Kessler, M; Appelbaum, K; Dümmler, W

    1989-12-01

    The Erlangen micro-lightguide spectrophotometer EMPHO 1 was designed for fast diffuse reflection (remission) spectrophotometry in small tissue volumes. The aim was to construct a compact, modular instrument with a high repetition rate which can be adapted to moving organs, e.g. the beating heart in situ, by the use of highly flexible micro-lightguides. Focusing problems, which cannot be solved when conventional optical devices such as microscopes are used in moving tissues, become negligible. A bandpass interference filter disk, which is rotated by a motor serves as a monochromating unit. One diffuse reflection spectrum in a selected wavelength domain is recorded during each revolution of the motor. Special filter disks, with spectral ranges of 400-520, 500-630, 600-1200 nm can be used for different tasks. The monochromated light is transmitted by means of a flexible fluid-lightguide to a photomultiplier tube. The electrical signal, which is proportional to the light intensity is recorded by an IBM-compatible AT. An analogue to digital converter has been developed for the AD conversion. Sampling of the spectra occurs in steps of 2 nm triggered by a decoding unit, containing an EPROM where the function between the wavelength-angular position characteristic of the filter disk is stored. A decoder wheel mounted on the same axle as the driving motor is used to program the decoder unit and to recall the wavelength position function. The decoding procedure enables a high wavelength reproducibility to be attained. The monochromating device allows a sampling velocity of 100 spectra per second. The EMPHO I has been successfully applied to experiments in the beating heart, the brain, the eye, the liver, the small intestine and the skeletal muscle of mammals. First investigations have also been performed in the heart during open heart surgery and in human skin. The apparatus has a high sampling rate and the small catchment volume allows measurements of remission spectra in

  3. Calibrating the Astronomical Extinction Spectrophotometer for NIST Stars

    NASA Astrophysics Data System (ADS)

    McGraw, John T.; Zimmer, P. C.; Karle, J.; Zirzow, D. C.; Cramer, C.; Lykke, K.; Woodward, J. T.

    2013-01-01

    The NIST Stars program is currently creating a new generation of absolutely calibrated spectroradiometric standard stars traceable to NIST laboratory standards. A fundamental task required to accomplish this is the transfer of the laboratory irradiance standard to telescopes in the field. We describe the system for calibration transfer for the Astronomical Extinction Spectrophotometer (AESOP), a 100mm diameter objective grating spectrometer designed to precisely and accurately measure the spectral energy distribution of bright (V<6) stars. The transfer standard for AESoP is a nearly identical 100mm diameter optical system with no dispersive element, CAL, which is co-mounted with AESoP but can be easily removed and taken to NIST for calibration in their Telescope Calibration Facility (TCF). CAL is designed to measure one wavelength at a time using a novel technique where CAL’s input pupil is imaged onto a CCD read out in TDI mode. The row read rate and on-chip binning can be modulated to match a very large dynamic range, from 100aW at a signal-to-noise ratio of 10 per second to 1nW at a signal-to-noise of >20000 per second. Moreover, CAL never observes the sky, only calibration sources and otherwise has its aperture covered to prevent dust accumulation. In the TCF, CAL measures a wavelength-tunable source that is simultaneous monitored using a NIST working standard photodiode. The responsivity of the photodiode and its distance from the source is accurately known. The distance from CAL to the source, of the order 50m, is also accurately known, as is CAL’s collecting area, allowing highly accurate transfer of the diode calibration to CAL. In AESoP’s mobile calibration lab, CAL and AESoP are mounted side-by-side with apertures aligned and both observe a collimated, tunable source that simultaneously illuminates both systems. AESoP and CAL are currently under field testing. We present calibration data and some initial stellar spectral energy distribution

  4. Results from laboratory and field testing of nitrate measuring spectrophotometers

    USGS Publications Warehouse

    Snazelle, Teri T.

    2015-01-01

    In Phase II, the analyzers were deployed in field conditions at three diferent USGS sites. The measured nitrate concentrations were compared to discrete (reference) samples analyzed by the Direct UV method on a Shimadzu UV1800 bench top spectrophotometer, and by the National Environmental Methods Index (NEMI) method I-2548-11 at the USGS National Water Quality Laboratory. The first deployment at USGS site 0249620 on the East Pearl River in Hancock County, Mississippi, tested the ability of the TriOs ProPs (10-mm path length), Hach NITRATAX (5 mm), Satlantic SUNA (10 mm), and the S::CAN Spectro::lyser (5 mm) to accurately measure low-level (less than 2 mg-N/L) nitrate concentrations while observing the effect turbidity and colored dissolved organic matter (CDOM) would have on the analyzers' measurements. The second deployment at USGS site 01389005 Passaic River below Pompton River at Two Bridges, New Jersey, tested the analyzer's accuracy in mid-level (2-8 mg-N/L) nitrate concentrations. This site provided the means to test the analyzers' performance in two distinct matrices—the Passaic and the Pompton Rivers. In this deployment, three instruments tested in Phase I (TriOS, Hach, and SUNA) were deployed with the S::CAN Spectro::lyser (35 mm) already placed by the New Jersey Water Science Center (WSC). The third deployment at USGS site 05579610 Kickapoo Creek at 2100E Road near Bloomington, Illinois, tested the ability of the analyzers to measure high nitrate concentrations (greater than 8 mg-N/L) in turbid waters. For Kickapoo Creek, the HIF provided the TriOS (10 mm) and S::CAN (5 mm) from Phase I, and a SUNA V2 (5 mm) to be deployed adjacent to the Illinois WSC-owned Hach (2 mm). A total of 40 discrete samples were collected from the three deployment sites and analyzed. The nitrate concentration of the samples ranged from 0.3–22.2 mg-N/L. The average absolute difference between the TriOS measurements and discrete samples was 0.46 mg-N/L. For the combined data

  5. 1,8-Dihydroxyanthraquinone anchored on silica gel: synthesis and application as solid phase extractant for lead(II), zinc(II) and cadmium(II) prior to their determination by flame atomic absorption spectrometry.

    PubMed

    Goswami, Anupama; Singh, Ajai K

    2002-10-16

    A new chelating matrix has been prepared by immobilizing 1,8-dihydroxyanthraquinone (DHAQ) on silica gel modified with (3-aminopropyl)triethoxysilane. After characterizing the matrix with thermogravimetric analysis (TGA), cross polarization magic angle spinning (CPMAS) NMR and diffuse reflectance infrared fourier transformation (DRIFT) spectroscopy, it has been used to preconcentrate Pb(II), Cd(II) and Zn(II) prior to their determination by flame atomic absorption spectrometry. The optimum pH ranges for quantitative sorption are 6.0-7.5, 7.0-8.0 and 6.0-8.0 for Pb, Zn, and Cd, respectively. All the metal ions can be desorbed with 2 mol l(-1) HCl/HNO(3). The sorption capacity of the matrix has been found to be 76.0, 180.0 and 70.2 mumol g(-1) for Pb, Zn and Cd, respectively, with the preconcentration factor of approximately 200. The limits upto which electrolytes NaNO(3), NaCl, NaBr, Na(2)SO(4), Na(3)PO(4) sodium citrate, EDTA, glycine and humic acid and cations Ca(II), Mg(II), Cu(II), Co(II), Ni(II), Mn(II) Al(III), Cr(III) and Fe(III) can co-exist with the metal ions during their sorption without any adverse effect are reported. The lowest concentration of metal ions for quantitative recovery is 5.0 ng ml(-1) The simultaneous enrichment and determination of all the metals is possible if total load of metal ions is less than sorption capacity. The flame AAS was used to determine these metal ions in underground, tap and river water samples (relative standard deviation (R.S.D.)

  6. Fundamental studies to develop certified reference material to calibrate spectrophotometer in the ultraviolet region

    NASA Astrophysics Data System (ADS)

    da Conceição, F. C.; Borges, P. P.; Gomes, J. F. S.

    2016-07-01

    Spectrophotometry is the technique used in a great number of laboratories around the world. Quantitative determination of a high number of inorganic, organic and biological species can be made by spectrophotometry using calibrated spectrophotometers. International standards require the use of optical filters to perform the calibration of spectrophotometers. One of the recommended materials is the crystalline potassium dichromate (K2Cr2O7), which is used to prepare solutions in specific concentrations for calibration or verification of spectrophotometers in the ultraviolet (UV) spectral regions. This paper presents the results concerning the fundamental studies for developing a certified reference material (CRM) of crystalline potassium dichromate to be used as standard of spectrophotometers in order to contribute to reliable quantitative analyses.

  7. An ultraviolet-visible spectrophotometer automation system. Part 2: User's guide

    NASA Astrophysics Data System (ADS)

    Roth, G. S.; Teuschler, J. M.; Budde, W. L.

    1982-07-01

    The Ultraviolet-Visible Spectrophotometer (UVVIS) automation system facilitates computer-automated procedures for the analysis of chlorophyll concentrations and color evaluations of waters, as well as the quality assurance of the spectrophotometer. In addition to various types of reports, this system also offers plots of chlorophyll and color scan data for either plotting or non-plotting terminals. The UVVIS system also provides manual data-entry facilities for chlorophyll analysis and for three-filter photometer color analysis. The UVVIS system is described from a user's perspective. It concentrates on how one interacts with the system, and on what system features one may use. Two other related publications are 'An Ultraviolet-Visible Spectrophotometer Automation System - Part I Functional Specifications,' and 'An Ultraviolet-Visible Spectrophotometer Automation System - Part III Program Documentation.'

  8. Evaluation of the Guided Wave Model 200 Scanning Spectrophotometer for plutonium (VI) determination

    SciTech Connect

    Walker, L.F.; Temer, D.J.; Lujan, E.

    1991-04-01

    We measured the plutonium(VI) in 2M HNO{sub 3} using a Model 200 Guided Wave Scanning Spectrophotometer. In evaluating this instrument for use with the plutonium peak at 831 nm, we determined its precision, stability, and resolution. Chloride and other anions that can strongly complex plutonium must be removed before assay. Plutonium solutions that are free of these anions are diluted with 2M HNO{sub 3} and distributed into calibrated 50-mL volumetric flasks for analysis. The plutonium is oxidized by addition of ceric ammonium nitrate, diluted to 50 mL, and the net peak absorbance at 831 nm measured. The Guided Wave instrument does not completely resolve the plutonium(VI) peak at 831 nm. Poor resolution of the peak results in a lower apparent molar absorptivity (less sensitivity) and diminished compliance with Beer's Law, requiring higher order fits for calibration data. Also small changes in measurements caused by spectral drift of the instrument do not significantly limit its use on this system. Precisions of 0.07% relative for absorbance measurements enable us to quantitate changes resulting from temperature and nitric acid concentration. Absorbances from standards are used to generate a quadratic fit of the calibration data. We then use the quadratic coefficients combined with sample absorbances to calculate the plutonium content of samples. Our calibration data have precisions of 0.15% relative. Compared with coulometric results, assay recoveries are 100.0% with a relative standard deviation of 0.2% for samples (both oxides and nitrates). Once system variables for the chemistry are controlled, the instrument can successfully measure total plutonium in samples. We discuss some system parameters, including nitric acid concentration and temperature at varying plutonium concentrations. Finally, we describe a procedure to assay plutonium content in plutonium oxide and plutonium nitrate solutions. 10 refs., 5 figs., 5 tabs.

  9. Measurement of protein-like fluorescence in river and waste water using a handheld spectrophotometer.

    PubMed

    Baker, Andy; Ward, David; Lieten, Shakti H; Periera, Ryan; Simpson, Ellie C; Slater, Malcolm

    2004-07-01

    Protein-like fluorescence intensity in rivers increases with increasing anthropogenic DOM inputs from sewerage and farm wastes. Here, a portable luminescence spectrophotometer was used to investigate if this technology could be used to provide both field scientists with a rapid pollution monitoring tool and process control engineers with a portable waste water monitoring device, through the measurement of river and waste water tryptophan-like fluorescence from a range of rivers in NE England and from effluents from within two waste water treatment plants. The portable spectrophotometer determined that waste waters and sewerage effluents had the highest tryptophan-like fluorescence intensity, urban streams had an intermediate tryptophan-like fluorescence intensity, and the upstream river samples of good water quality the lowest tryptophan-like fluorescence intensity. Replicate samples demonstrated that fluorescence intensity is reproducible to +/- 20% for low fluorescence, 'clean' river water samples and +/- 5% for urban water and waste waters. Correlations between fluorescence measured by the portable spectrophotometer with a conventional bench machine were 0.91; (Spearman's rho, n = 143), demonstrating that the portable spectrophotometer does correlate with tryptophan-like fluorescence intensity measured using the bench spectrophotometer.

  10. An ultraviolet-visible spectrophotometer automation system. Part 3: Program documentation

    NASA Astrophysics Data System (ADS)

    Roth, G. S.; Teuschler, J. M.; Budde, W. L.

    1982-07-01

    The Ultraviolet-Visible Spectrophotometer (UVVIS) automation system accomplishes 'on-line' spectrophotometric quality assurance determinations, report generations, plot generations and data reduction for chlorophyll or color analysis. This system also has the capability to process manually entered data for the analysis of chlorophyll or color. For each program of the UVVIS system, this document contains a program description, flowchart, variable dictionary, code listing, and symbol cross-reference table. Also included are descriptions of file structures and of routines common to all automated analyses. The programs are written in Data General extended BASIC, Revision 4.3, under the RDOS operating systems, Revision 6.2. The BASIC code has been enhanced for real-time data acquisition, which is accomplished by CALLS to assembly language subroutines. Two other related publications are 'An Ultraviolet-Visible Spectrophotometer Automation System - Part I Functional Specifications,' and 'An Ultraviolet-Visible Spectrophotometer Automation System - Part II User's Guide.'

  11. Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

    PubMed

    Tait, Zachary S; Thompson, Megan; Stubbins, Aron

    2015-07-01

    The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA.

  12. Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

    PubMed

    Tait, Zachary S; Thompson, Megan; Stubbins, Aron

    2015-07-01

    The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA. PMID:26437114

  13. Objective evaluation of whiteness of cooked rice and rice cakes using a portable spectrophotometer.

    PubMed

    Goto, Hajime; Asanome, Noriyuki; Suzuki, Keitaro; Sano, Tomoyoshi; Saito, Hiroshi; Abe, Yohei; Chuba, Masaru; Nishio, Takeshi

    2014-03-01

    The whiteness of cooked rice and rice cakes was evaluated using a portable spectrophotometer with a whiteness index (WI). Also, by using boiled rice for measurement of Mido values by Mido Meter, it was possible to infer the whiteness of cooked rice without rice cooking. In the analysis of varietal differences of cooked rice, 'Tsuyahime', 'Koshihikari' and 'Koshinokaori' showed high whiteness, while 'Satonoyuki' had inferior whiteness. The whiteness of rice cakes made from 'Koyukimochi' and 'Dewanomochi' was higher than the whiteness of those made from 'Himenomochi' and 'Koganemochi'. While there was a significant correlation (r = 0.84) between WI values and whiteness scores of cooked rice by the sensory test, no correlation was detected between the whiteness scores and Mido values, indicating that the values obtained by a spectrophotometer differ from those obtained by a Mido Meter. Thus, a spectrophotometer may be a novel device for measurement of rice eating quality.

  14. Spec UV-Vis: An Ultraviolet-Visible Spectrophotometer Simulation

    NASA Astrophysics Data System (ADS)

    Papadopoulos, N.; Limniou, Maria; Koklamanis, Giannis; Tsarouxas, Apostolos; Roilidis, Mpampis; Bigger, Stephen W.

    2001-11-01

    The software and its accompanying manual can be used to illustrate the recording of an absorption spectrum and the Beer-Lambert law (5-7) as well as various aspects of acid-base indicators such as the spectrophotometric determination of pKa (8), the isosbestic point (6, 9), and distribution diagrams (10, 11).

    Literature Cited

    1. Shiowatana, J. J. Chem. Educ. 1997, 74, 730.
    2. Altemose, I. R. J. Chem. Educ. 1986, 63, A216, A262.
    3. Piepmeier, E. H. J. Chem. Educ. 1973, 50, 640.
    4. Lott, P. F. J. Chem. Educ. 1968, 45, A89, A169, A182, A273.
    5. Skoog, D. A.; West, D. M.; Holler, F. J. Fundamentals of Analytical Chemistry, 7th ed.; Saunders College Publishing: Fort Worth, TX, 1996, Chapters 22-24.
    6. Christian, G. D. Analytical Chemistry, 5th ed.; Wiley: New York, 1994; Chapter 14.
    7. Kennedy, J. H. Analytical Chemistry--Principles, 2nd ed.; Saunders College Publishing: New York, 1990; Chapters 11,12.
    8. Patterson, G. S. J. Chem. Educ. 1999, 76, 395.
    9. Harris, D. C. Quantitative Chemical Analysis, 5th ed.; Freeman: New York, 1997; Chapters 19, 20.
    10. Butler, J. N. Ionic Equilibrium--A Mathematical Approach; Addison-Wesley: Reading, MA, 1964; Chapter 5.
    11. Sawyer, C. A.; McCarty, P. L.; Parkin, G. F. Chemistry for Environmental Engineering, 4th ed.; McGraw-Hill: Singapore, 1994; Chapter 4.

  15. Improved entrance optic for global irradiance measurements with a Brewer spectrophotometer.

    PubMed

    Gröbner, Julian

    2003-06-20

    A new entrance optic for a Brewer spectrophotometer has been designed and tested both in the laboratory and during solar measurements. The integrated cosine response deviates by 2.4% from the ideal, with an uncertainty of +/- 1%. The systematic uncertainties of global solar irradiance measurements with this new entrance optic are considerably reduced compared with measurements with the traditional design. Simultaneous solar irradiance measurements between the Brewer spectrophotometer and a spectroradiometer equipped with a state-of-the-art shaped diffuser agreed to within +/- 2% during a five-day measurement period. PMID:12833953

  16. Fighting Prior Review.

    ERIC Educational Resources Information Center

    Bowen, John

    1990-01-01

    Reviews arguments for and against prior administrative review and censorship of student expression. Suggests that prior review strips any pretense of democracy from many American educational institutions. Argues that prior review is journalistically inappropriate, educationally unsound, and practically illogical. (KEH)

  17. [An optical-fiber-sensor-based spectrophotometer for soil non-metallic nutrient determination].

    PubMed

    He, Dong-xian; Hu, Juan-xiu; Lu, Shao-kun; He, Hou-yong

    2012-01-01

    In order to achieve rapid, convenient and efficient soil nutrient determination in soil testing and fertilizer recommendation, a portable optical-fiber-sensor-based spectrophotometer including immersed fiber sensor, flat field holographic concave grating, and diode array detector was developed for soil non-metallic nutrient determination. According to national standard of ultraviolet and visible spectrophotometer with JJG 178-2007, the wavelength accuracy and repeatability, baseline stability, transmittance accuracy and repeatability measured by the prototype instrument were satisfied with the national standard of III level; minimum spectral bandwidth, noise and excursion, and stray light were satisfied with the national standard of IV level. Significant linear relationships with slope of closing to 1 were found between the soil available nutrient contents including soil nitrate nitrogen, ammonia nitrogen, available phosphorus, available sulfur, available boron, and organic matter measured by the prototype instrument compared with that measured by two commercial single-beam-based and dual-beam-based spectrophotometers. No significant differences were revealed from the above comparison data. Therefore, the optical-fiber-sensor-based spectrophotometer can be used for rapid soil non-metallic nutrient determination with a high accuracy. PMID:22497162

  18. Analog Spectrophotometers in the Digital Age: Data Acquisition on a Budget

    ERIC Educational Resources Information Center

    Nazarenko, Alexander Y.; Nazarenko, Natalie A.

    2005-01-01

    The interfacing of various spectrometers with analog output to a personal computer running Microsoft Excel in the Windows environment is described. This low cost data acquisition solution is a useful replacement of a chart recorder for various UV-visible and infrared scanning spectrophotometers.

  19. An Improved Flame Test for Qualitative Analysis Using a Multichannel UV-Visible Spectrophotometer

    ERIC Educational Resources Information Center

    Blitz, Jonathan P.; Sheeran, Daniel J.; Becker, Thomas L.

    2006-01-01

    Qualitative analysis schemes are used in undergraduate laboratory settings as a way to introduce equilibrium concepts and logical thinking. The main component of all qualitative analysis schemes is a flame test, as the color of light emitted from certain elements is distinctive and a flame photometer or spectrophotometer in each laboratory is…

  20. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  1. Fiberoptic spectrophotometer

    DOEpatents

    Tans, P.P.; Lashof, D.A.

    1986-12-23

    A device is described for determining the relative composition of a sample of a gas by comparison of the Raman-scattered light of the sample with that of a known gas comprising: a means for passing a single light source through the unknown and the known gases, choppers to alternate the Raman-scattered light into a common light detection and measuring system, optical fiber networks for spatially mixing the resulting Raman scattered light from each sample and directing the mixed light to selective detectors, and a compiler to record the light intensity of each wavelength of Raman-scattered light as a function of the sample from which it originated. 6 figs.

  2. Fiberoptic spectrophotometer

    DOEpatents

    Tans, Petrus P.; Lashof, Daniel A.

    1986-01-01

    A device for determining the relative composition of a sample of a gas by comparison of the Raman-scattered light of the sample with that of a known gas comprising: a means for passing a single light source through the unknown and the known gases, choppers to alternate the Raman-scattered light into a common light detection and measuring system, optical fiber networks for spatially mixing the resulting Raman scattered light from each sample and directing the mixed light to selective detectors, and a compiler to record the light intensity of each wavelength of Raman-scattered light as a function of the sample from which it originated.

  3. Evaluation of a simple spectrophotometer to quantify fluorine gas from a cyclotron target

    NASA Astrophysics Data System (ADS)

    Janabi, M.; Childs, B. C.; Vandehey, N. T.; O'Neil, J. P.

    2012-12-01

    In an effort to more quickly evaluate the conditioning of our 18F-fluorine target and determine the amount of F2 that is released with each unload, a simple spectrophotometer was fabricated that aids in quantifying the I2 produced as a result of bubbling F2 gas into a solution of potassium iodide. A narrow range LED (470 ± 10 nm), combined with a wide range photodiode (320-1100 nm) were used to construct the simple spectrophotometer device. We were able to use this device to quantitate the amount of F2 released and obtained a good correlation (R2>0.991) with the values obtained by the "traditional" titration method.

  4. Automated Solar Tracking Spectrophotometer for Remote Sensing of Column Aerosol Optical Depth

    NASA Astrophysics Data System (ADS)

    Rainwater, B.; Arnott, W. P.; Moosmuller, H.; Karr, D.

    2012-12-01

    Aerosols in the atmosphere are poorly understood in terms of how they affect weather and climate. In an effort to advance this knowledge, an automated solar tracking spectrophotometer has been constructed to measure direct solar radiation from the ultraviolet to infrared. This instrument facilitates determination of solar irradiance, precipitable water, aerosol optical depth (AOD), and the Ångström turbidity exponent related to aerosol size distribution. Measurements with a CIMEL CE-318 sun photometer (part of the global NASA AERONET network) and a manual solar spectrophotometer are being used to evaluate the accuracy of our instrument. Upon successful evaluation, this instrument will provide a basis for research into spectral information that will supplement CIMEL measurements. Presented is the design of this instrument and measurement comparisons with the aforementioned instruments for the air above Reno, Nevada, USA.

  5. Solar UVB measurements with the double- and single-monochromator Brewer ozone spectrophotometers

    NASA Astrophysics Data System (ADS)

    Bais, A. F.; Zerefos, C. S.; McElroy, C. T.

    In this work, the new double-monochromator version of the Brewer Ozone Spectrophotometer, especially designed for spectral UV measurements, is briefly described and its measurements are compared with those obtained by a conventional, single-monochromator Brewer instrument. The comparison shows that the performance of the new instrument is much superior in the low UVB wavelengths (λ<305 nm), because of the much higher stray-light rejection capability of the instrument. The conventional Brewer spectrophotometer is capable of recording accurately solar UVB spectra at wavelengths greater than about 300 nm. The error in UVB dose calculations made using data from the conventional Brewer is estimated to be of the order of +1%, while the absolute irradiances at wavelengths below 300 nm may be overestimated by more than 10%, depending on the measured wavelength and the solar zenith angle.

  6. Stability study of standards used for calibration of the spectrophotometer wavelength scale

    NASA Astrophysics Data System (ADS)

    Debossan, L. F.; Carvalho, E. M. S.; Souza, M. A.; Gomes, J. F. S.

    2016-07-01

    The calibration of spectrophotometers is a procedure recommended by international standards to provide quality assurance of results and traceability. Due to its intrinsic properties, holmium oxide filters are indicated as reference standards for calibrating the wavelength scale of such equipment. This paper presents a study aiming to assess the repeatability and drift of holmium oxide standard filters calibrated in the Radiometry and Photometry Laboratory (Laraf) of Inmetro in order to verify their stability.

  7. A stopped-flow dual-wavelength spectrophotometer suitable for the study of respiratory chains.

    PubMed Central

    Garland, P B; Littleford, S J; Haddock, B A

    1976-01-01

    The requirements for a dual-wavelength stopped-flow spectrophotometer to be suitable for studying limited quantities of respiratory-chain preparations are described. They can be met by a design using mainly commercially available components. The constructed apparatus has a dead-time of approx. 2.6 ms, a mixing ratio of 17:1, and a minimal requirement for 0.5 ml of mixed reactants per flow. PMID:938452

  8. Development of spectrophotometer for breast tumor diagnostic spectrometer based on virtual instruments

    NASA Astrophysics Data System (ADS)

    Ren, Zhong; Liu, Guodong; Liu, Ying; Huang, Zhen

    2013-12-01

    Although some progresses have been achieved by the traditional diagnostic methods, such as X mammography, computer tomography (CT) imaging and magnetic resonance imaging (MRI) etc, their applications are limited by some drawbacks to some extent. As a more promising alternative method, the breast tumor diagnosis method based on infrared spectrometer was introduced. According to the theory of spectral unique characteristics for matter, i.e. the spectrums are different for the matter with different properties, so the spectrums are different between the tumor and normal tissues. Therefore, a spectrometer system was developed to diagnose the breast tumor in this paper. Meanwhile, a spectrophotometer for breast tumor diagnostic spectrometer was designed, and the plane holography concave (PHV) grating was used as the dispersion device in this spectrophotometer because of excellent performances. In this system, linear CCD detector combined with PCI data acquisition card was used as the spectral detector, and the virtual instruments (VI) technique was used to control the data acquisition and data processing. In experiments, the spectral calibration based on mercury lamp was performed. Experimental results illustrated that the construction of the spectrophotometer system is available, the spectral range is from 300-850nm, its wavelength resolution reached 2nm. The simulation experimental result proved that the design of the diagnostic system was very satisfied and diagnostic method was also feasible.

  9. Improved estimation of reflectance spectra by utilizing prior knowledge.

    PubMed

    Dierl, Marcel; Eckhard, Timo; Frei, Bernhard; Klammer, Maximilian; Eichstädt, Sascha; Elster, Clemens

    2016-07-01

    Estimating spectral reflectance has attracted extensive research efforts in color science and machine learning, motivated through a wide range of applications. In many practical situations, prior knowledge is available that ought to be used. Here, we have developed a general Bayesian method that allows the incorporation of prior knowledge from previous monochromator and spectrophotometer measurements. The approach yields analytical expressions for fast and efficient estimation of spectral reflectance. In addition to point estimates, probability distributions are also obtained, which completely characterize the uncertainty associated with the reconstructed spectrum. We demonstrate that, through the incorporation of prior knowledge, our approach yields improved reconstruction results compared with methods that resort to training data only. Our method is particularly useful when the spectral reflectance to be recovered resides beyond the scope of the training data. PMID:27409695

  10. Dobson spectrophotometer total ozone measurement errors caused by interfering absorbing species such as SO2, NO2, and photochemically produced O3 in polluted air

    NASA Astrophysics Data System (ADS)

    Komhyr, W. D.; Evans, R. D.

    1980-02-01

    Total ozone measurements made with Dobson spectrophotometers in polluted air are subject to errors caused by interfering trace gas species that absorb solar ultraviolet radiation. While such interference is probably non-existent or small at the majority of Dobson instrument stations throughout the world, errors of up to 25% and 5%, resulting from absorption by SO2 and NO2 respectively, may occur occasionally at a few stations located in extremely polluted atmospheres. Interference by other absorbers, including N2O5, H2O2, HNO3, acetyldehyde, acetone, and acrolein has been found to be negligible. Ozone produced photochemically in polluted near-surface air may occasionally constitute from 5% to 10% of the atmospheric total ozone column. Such ozone interferes with measurements of atmospheric background total ozone.

  11. Heavy metals in brick kiln located area using atomic absorption spectrophotometer: a case study from the city of Peshawar, Pakistan.

    PubMed

    Ishaq, M; Khan, Murad Ali; Jan, F Akbar; Ahmad, I

    2010-07-01

    Environmental pollution is one of the burning issues of the world. In developed countries, there are lot of awareness about the environment and the impact of various industries on their life and surroundings. A little has been done in this direction in developing countries. In Pakistan, a big problem is the rapid conglomeration of the brick kilns in the outskirts of nearly all the urban centers to cope with the rapid construction work in big cities. A huge amount of low-grade coal or rubber tires is used as fuel in a very non-scientific manner. The purpose of the present study was to look into the impact of the brick kilns on the different aspects of environmental pollution caused by these kilns. Concentration of metals Cu, Co, Zn, Pb, Cr, Ni, Cd, and Mn were measured on 36 soil samples collected from the area and the same number of plant samples in order to establish the distribution of heavy metals in the area and to determine the effect of this distribution on the surrounding atmosphere and the possible effects on human life.

  12. Displacement-dispersive liquid-liquid microextraction based on solidification of floating organic drop of trace amounts of palladium in water and road dust samples prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Ghanbarian, Maryam; Afzali, Daryoush; Mostafavi, Ali; Fathirad, Fariba

    2013-01-01

    A new displacement-dispersive liquid-liquid microextraction method based on the solidification of floating organic drop was developed for separation and preconcentration of Pd(ll) in road dust and aqueous samples. This method involves two steps of dispersive liquid-liquid microextraction based on solidification. In Step 1, Cu ions react with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which is extracted by dispersive liquid-liquid microextraction based on a solidification procedure using 1-undecanol (extraction solvent) and ethanol (dispersive solvent). In Step 2, the extracted complex is first dispersed using ethanol in a sample solution containing Pd ions, then a dispersive liquid-liquid microextraction based on a solidification procedure is performed creating an organic drop. In this step, Pd(ll) replaces Cu(ll) from the pre-extracted Cu-DDTC complex and goes into the extraction solvent phase. Finally, the Pd(ll)-containing drop is introduced into a graphite furnace using a microsyringe, and Pd(ll) is determined using atomic absorption spectrometry. Several factors that influence the extraction efficiency of Pd and its subsequent determination, such as extraction and dispersive solvent type and volume, pH of sample solution, centrifugation time, and concentration of DDTC, are optimized.

  13. Image-based ELISA on an activated polypropylene microtest plate--a spectrophotometer-free low cost assay technique.

    PubMed

    Parween, Shahila; Nahar, Pradip

    2013-10-15

    In this communication, we report ELISA technique on an activated polypropylene microtest plate (APPµTP) as an illustrative example of a low cost diagnostic assay. Activated test zone in APPµTP binds a capture biomolecule through covalent linkage thereby, eliminating non-specific binding often prevalent in absorption based techniques. Efficacy of APPµTP is demonstrated by detecting human immunoglobulin G (IgG), human immunoglobulin E (IgE) and Aspergillus fumigatus antibody in patient's sera. Detection is done by taking the image of the assay solution by a desktop scanner and analyzing the color of the image. Human IgE quantification by color saturation in the image-based assay shows excellent correlation with absorbance-based assay (Pearson correlation coefficient, r=0.992). Significance of the relationship is seen from its p value which is 4.087e-11. Performance of APPµTP is also checked with respect to microtiter plate and paper-based ELISA. APPµTP can quantify an analyte as precisely as in microtiter plate with insignificant non-specific binding, a necessary prerequisite for ELISA assay. In contrast, paper-ELISA shows high non-specific binding in control sera (false positive). Finally, we have carried out ELISA steps on APPµTP by ultrasound waves on a sonicator bath and the results show that even in 8 min, it can convincingly differentiate a test sample from a control sample. In short, spectrophotometer-free image-based miniaturized ELISA on APPµTP is precise, reliable, rapid, and sensitive and could be a good substitute for conventional immunoassay procedures widely used in clinical and research laboratories.

  14. Monitoring of rain events with a submersible UV/VIS spectrophotometer.

    PubMed

    Maribas, Aurélien; Laurent, Nadège; Battaglia, Philippe; do Carmo Lourenço da Silva, Maria; Pons, Marie-Noële; Loison, Bernard

    2008-01-01

    A submersible UV/VIS spectrophotometer has been implemented on the pre-treatment unit of a large-scale wastewater treatment plant (350,000 person-equivalent) to monitor the rapid changes in total Suspended Solids and total Chemical Oxygen Demand occurring during rain events as well as injections of reject water from the sludge treatment train or wasted activated sludge. Calibration has been proven to be difficult for fast composition-varying streams but the device is able to monitor qualitatively sudden quality changes, in spite of the noise affecting the signal.

  15. Flight of a UV spectrophotometer aboard Galileo 2, the NASA Convair 990 aircraft

    NASA Technical Reports Server (NTRS)

    Sellers, B.; Hunderwadel, J. L.; Hanser, F. A.

    1976-01-01

    An ultraviolet interference-filter spectrophotometer (UVS) fabricated for aircraft-borne use on the DOT Climatic Impact Assessment Program (CIAP) has been successfully tested in a series of flights on the NASA Convair 990, Galileo II. UV flux data and the calculated total ozone above the flight path are reported for several of the flights. Good agreement is obtained with the total ozone as deducted by integration of an ozone sonde vertical profile obtained at Wallops Island, Virginia near the time of a CV-990 underpass. Possible advantages of use of the UVS in the NASA Global Atmospheric Sampling Program are discussed.

  16. Visible light nitrogen dioxide spectrophotometer intercomparison: Mount Kobau, British Columbia, July 28 to August 10, 1991

    NASA Technical Reports Server (NTRS)

    Mcelroy, C. T.; Elokhov, A. S.; Elansky, N.; Frank, H.; Johnston, P.; Kerr, J. B.

    1994-01-01

    Under the auspices of the World Meteorological Organization, Environment Canada hosted an international comparison of visible light spectrophotometers at Mt. Kobau, British Columbia in August of 1991. Instruments from four countries were involved. The intercomparison results have indicated that some significant differences exist in the responses of the various instruments, and have provided a basis for the comparison of the historical data sets which currently exist as a result of the independent researches carried out in the past in the former Soviet Union, New Zealand, and Canada.

  17. Constructing priors in synesthesia.

    PubMed

    van Leeuwen, Tessa M

    2014-01-01

    A new theoretical framework (PPSMC) applicable to synesthesia has been proposed, in which the discrepancy between the perceptual reality of (some) synesthetic concurrents and their subjective non-veridicality is being explained. The PPSMC framework stresses the relevance of the phenomenology of synesthesia for synesthesia research-and beyond. When describing the emergence and persistence of synesthetic concurrents under PPSMC, it is proposed that precise, high-confidence priors are crucial in synesthesia. I discuss the construction of priors in synesthesia.

  18. Novel spectrophotometer for the investigation of short term variability in stellar spectra.

    PubMed

    Stiff, T; Jeffers, S

    1978-06-01

    A variety of astronomical objects (e.g., O(f) stars, B(e) stars, optical counterparts of X-ray sources, etc.) exhibit emission line spectra. For some of these objects the emission line strengths are suspected as being variable (and possibly periodic) over time scales as short as minutes or less. A spectrophotometer has been built whose output signal is a measure of the line strength only. The spectrophotometer is used to look at the emission feature and the adjacent continuum in rapid succession by means of magnetic modulation of the electron image of the optical spectrum in an image tube, thus generating a modulated signal which is detected with a lockin amplifier. This detection technique essentially subtracts off an instrumental dark current signal due to sky background and the signal due to the continuum of the star giving a real time measure of the line strength only. The design of the instrument, its laboratory calibration, and some preliminary observational data are presented. PMID:20198073

  19. Online inspection of poultry carcasses using a visible/near-infrared spectrophotometer

    NASA Astrophysics Data System (ADS)

    Chen, Yud-Ren; Hruschka, William R.; Early, Howard

    1999-01-01

    The Instrumentation and Sensing Laboratory (ISL) has developed an industrial prototype diode-array visible/near-infrared (Vis/NIR) spectrophotometer system for inspecting poultry for diseased and defective carcasses on-line. The ISL design is based on the principle that wholesome and diseased and defective birds have different chemical compositions of tissues and may have different skin color. This visible/near- infrared spectrophotometer system has been tested off-line at 60 and 90 birds per minute. On-line trials of the visible/near-infrared chicken carcass inspection system were conducted during an 8-day period in a slaughter plant in New Holland, Pennsylvania, where spectra (470 - 960 nm) of 1174 normal and 576 abnormal (diseased and/or defective) chicken carcasses were measured. The instrument measured the spectra of veterinarian-selected carcasses as they passed on a processing line at a speed of 70 birds per minute. Classification models using principal component analysis as a data pretreatment for input into neural networks were able to classify the carcasses from the spectral data with a success rate of 95%. Data from 3 days can predict the subsequent two days' chickens with high accuracy. This accuracy was consistent with the results obtained previously on off-line studies. Thus, the method shows promise for separation of diseased and defective carcasses from wholesome carcasses in a partially automated inspection system. Details of the models using various training regimens are discussed.

  20. Novel spectrophotometer for the investigation of short term variability in stellar spectra.

    PubMed

    Stiff, T; Jeffers, S

    1978-06-01

    A variety of astronomical objects (e.g., O(f) stars, B(e) stars, optical counterparts of X-ray sources, etc.) exhibit emission line spectra. For some of these objects the emission line strengths are suspected as being variable (and possibly periodic) over time scales as short as minutes or less. A spectrophotometer has been built whose output signal is a measure of the line strength only. The spectrophotometer is used to look at the emission feature and the adjacent continuum in rapid succession by means of magnetic modulation of the electron image of the optical spectrum in an image tube, thus generating a modulated signal which is detected with a lockin amplifier. This detection technique essentially subtracts off an instrumental dark current signal due to sky background and the signal due to the continuum of the star giving a real time measure of the line strength only. The design of the instrument, its laboratory calibration, and some preliminary observational data are presented.

  1. Flameless atomic-absorption determination of gold in geological materials

    USGS Publications Warehouse

    Meier, A.L.

    1980-01-01

    Gold in geologic material is dissolved using a solution of hydrobromic acid and bromine, extracted with methyl isobutyl ketone, and determined using an atomic-absorption spectrophotometer equipped with a graphite furnace atomizer. A comparison of results obtained by this flameless atomic-absorption method on U.S. Geological Survey reference rocks and geochemical samples with reported values and with results obtained by flame atomic-absorption shows that reasonable accuracy is achieved with improved precision. The sensitivity, accuracy, and precision of the method allows acquisition of data on the distribution of gold at or below its crustal abundance. ?? 1980.

  2. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis. PMID:20072266

  3. A Possibility Study on Gender Recognition Method Using Near Infrared Ray Scanning Spectrophotometer

    NASA Astrophysics Data System (ADS)

    Nishino, Satoshi; Ohshima, Kenji

    Male and female recognition is necessary to make security stronger and when various statistics on the visitor are taken in commercial facilities and so on. The conventional method of male and female recognition is currently determined by using the person's appearance, the person's dress and in such cases, the way of walking, the foot pressure, the hair type. But, these characteristics can be intentionally changed by human intervention or design. The proposed method gets a difference in the male's and female's characteristics by taking absorbance characteristic of the fat distribution of the person's cheek by near infrared ray scanning spectrophotometer. This is a male and female recognition based on the new concept idea which this is used for. Consequently, this can be used to recognize a male from a female even if a male turns himself into the female intentionally (and vice versa), because this method involves biometrics authentication.

  4. Fourier-transform spectrophotometer for time-resolved emission measurements using a 100-point transient digitizer

    NASA Astrophysics Data System (ADS)

    Preses, Jack M.; Hall, Gregory E.; Muckerman, James T.; Sears, Trevor J.; Weston, Ralph E., Jr.; Guyot, Christian; Hanson, Jonathan C.; Flynn, George W.; Bernstein, Herbert J.

    1993-01-01

    An infrared time-resolved Fourier-transform emission spectrophotometer was constructed and its use demonstrated. The instrument is based on a commercial interferometer combined with a data acquisition system. Operation in a smooth scan mode and the use of a transient digitizer provides good time efficiency for data acquisition and reduces the need to maintain constant energy pulses for long periods of time. An entire 100-point time history of a single point of an interferogram is obtained from a single laser pulse and usable data can be obtained from 10 to 50 mirror scans. The experimental apparatus, data acquisition program, and data evaluation are reviewed. Time-resolved Fourier-transform spectroscopy is an efficient method of determining the dynamics of molecular reactions and relaxation.

  5. High sensitive pulse oximeter-spectrophotometer for laser-optical dosimetry in biology and medicine

    NASA Astrophysics Data System (ADS)

    Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.; Mamilov, S. A.; Plaksiy, Yu. S.

    2006-03-01

    High sensitive multi channel pulse oxymeter - spectrophotometer for control of the local tissue oxygen saturation is presented. Due to an original method of data storing and processing the accuracy of measurements 3-4 times are increased in compare with similar systems. This system is used for registration of the local changes of arterial blood saturation with oxygen under effect of low intensity laser radiation. It is shown that the photodissociation of oxyhemoglobin in cutaneous blood vessels play a dominant role in the mechanism of biostimulating and therapeutic effect of low intensity laser radiation. The results of experimental investigation in vivo the dependence of arterial oxygen blood saturation on temperature and the wavelength of laser radiation are presented. It is suggested that dosimetry for laser therapy could be base on regulation of local concentration of free oxygen in tissue.

  6. Total ozone trends over the USA during 1979-1991 from Dobson spectrophotometer observations

    NASA Technical Reports Server (NTRS)

    Komhyr, Walter D.; Grass, Robert D.; Koenig, Gloria L.; Quincy, Dorothy M.; Evans, Robert D.; Leonard, R. Kent

    1994-01-01

    Ozone trends for 1979-1991, determined from Dobson spectrophotometer observations made at eight stations in the United States, are augmented with trend data from four foreign cooperative stations operated by NOAA/CMDL. Results are based on provisional data archived routinely throughout the years at the World Ozone Data Center in Toronto, Canada, with calibration corrections applied to some of the data. Trends through 1990 exhibit values of minus 0.3 percent to minus 0.5 percent yr(exp -1) at mid-to-high latitudes in the northern hemisphere. With the addition of 1991 data, however, the trends become less negative, indicating that ozone increased in many parts of the world during 1991. Stations located within the plus or minus 20 deg N-S latitude band exhibit no ozone trends. Early 1992 data show decreased ozone values at some of the stations. At South Pole, Antarctica, October ozone values have remained low during the past 3 years.

  7. SphinX soft X-ray spectrophotometer: Science objectives, design and performance

    NASA Astrophysics Data System (ADS)

    Gburek, S.; Sylwester, J.; Kowalinski, M.; Bakala, J.; Kordylewski, Z.; Podgorski, P.; Plocieniak, S.; Siarkowski, M.; Sylwester, B.; Trzebinski, W.; Kuzin, S. V.; Pertsov, A. A.; Kotov, Yu. D.; Farnik, F.; Reale, F.; Phillips, K. J. H.

    2011-06-01

    The goals and construction details of a new design Polish-led X-ray spectrophotometer are described. The instrument is aimed to observe emission from entire solar corona and is placed as a separate block within the Russian TESIS X- and EUV complex aboard the CORONAS-PHOTON solar orbiting observatory. SphinX uses silicon PIN diode detectors for high time resolution measurements of the solar spectra in the range 0.8-15 keV. Its spectral resolution allows for discerning more than hundred separate energy bands in this range. The instrument dynamic range extends two orders of magnitude below and above these representative for GOES. The relative and absolute accuracy of spectral measurements is expected to be better than few percent, as follows from extensive ground laboratory calibrations.

  8. Headaches prior to earthquakes

    NASA Astrophysics Data System (ADS)

    Morton, L. L.

    1988-06-01

    In two surveys of headaches it was noted that their incidence had increased significantly within 48 h prior to earthquakes from an incidence of 17% to 58% in the first survey using correlated samples and from 20.4% to 44% in the second survey using independent samples. It is suggested that an increase in positive air ions from rock compression may trigger head pain via a decrease in brain levels of the neurotransmitter serotonin. The findings are presented as preliminary, with the hope of generating further research efforts in areas more prone to earthquakes.

  9. Sensitive determination of mercury by a miniaturized spectrophotometer after in situ single-drop microextraction.

    PubMed

    Yang, Fangwen; Liu, Rui; Tan, Zhiqiang; Wen, Xiaodong; Zheng, Chengbin; Lv, Yi

    2010-11-15

    An in situ single-drop microextraction (SDME) method was developed for trace mercury determination by a miniaturized spectrophotometer, in which a simple and cheap light-emitting diode (LED) was employed as the light source, and a handheld charge coupled device (CCD) was served as the detector. A droplet of 0.006% dithizone-CCl(4) (m/v) was used as extraction phase and hanged on a rolled PTFE tube. LED light was adjusted carefully to pass through the centre of the droplet and the entrance slit of the CCD detector. The radiation intensities of 475 nm before and after SDME (I(0) and I(i)) were recorded for quantification. Under the optimum conditions, the system provided a linear range of 2-50 μg L(-1), with a correlation coefficient of 0.9983 and a limit of detection (3σ) of 0.2 μg L(-1). The enrichment factor was about 69. The present method showed the merits of high sensitivity, simplicity, rapidity, low reagent consumption and field analysis potential. Finally, this method was successfully applied for the determination of the total mercury in spiked tap water sample, spiked river water sample and certified reference material (GBW (E) 080393, simulated water). PMID:20696521

  10. A study of a sector spectrophotometer and auroral O+(2P-2D) emissions

    NASA Technical Reports Server (NTRS)

    Swenson, G. R.

    1976-01-01

    The metastable O+(2P-2D) auroral emission was investigated. The neighboring OH contaminants and low intensity levels of the emission itself necessitated the evolution of an instrument capable of separating the emission from the contaminants and having a high sensitivity in the wavelength region of interest. A new type of scanning photometer was developed and its properties are discussed. The theoretical aspects of auroral electron interaction with atomic oxygen and the resultant O+(2P-2D) emissions were examined in conjunction with N2(+)1NEG emissions. Ground based measurements of O+(2P-2D) auroral emission intensities were made using the spatial scanning photometer (sector spectrophotometer). Simultaneous measurements of N2(+)1NEG sub 1,0 emission intensity were made in the same field of view using a tilting photometer. Time histories of the ratio of these two emissions made in the magnetic zenith during auroral breakup periods are given. Theories of I sub 7319/I sub 4278 of previous investigators were presented. A rocket measurement of N2(+)1NEG sub 0,0 and O+(2P-2D) emission in aurora was examined in detail and was found to agree with the ground based measurements. Theoretical examination resulted in the deduction of the electron impact efficiency generating O+(2P) and also suggests a large source of O+(2P) at low altitude. A possible source is charge exchange of N+(1S) with OI(3P).

  11. Total ozone measurements made with the Brewer ozone spectrophotometer during STOIC 1989

    NASA Astrophysics Data System (ADS)

    Kerr, J. B.; McElroy, C. T.

    1995-05-01

    The Canadian Atmospheric Environment Service participated in the Stratospheric Ozone Intercomparison Campaign (STOIC) by operating a Brewer ozone spectrophotometer at the Table Mountain Observatory from July 19 to August 2, 1989. Frequent direct Sun measurements of total column ozone were made throughout most days during the 2 weeks of the intercomparison. Results of the Brewer instrument total ozone measurements are given. They show that there is a diurnal variation of total ozone with values increasing on average by 6.6±2.4 Dobson units between early morning and late afternoon. Comparing the total ozone measurements with ozone concentration measurements made at ground level suggests that the daytime increase is a result of a buildup of surface ozone during the day. The total ozone measurements made by the Brewer instrument during STOIC are compared with total ozone measurements made by the National Oceanic and Atmospheric Administration (NOAA) Dobson instrument, the NASA/Wallops electrochemical concentration cell ozonesondes and the total ozone mapping spectrometer satellite instrument.

  12. Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions.

    PubMed

    Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

    2016-01-01

    On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology-fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01-0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics. PMID:27352840

  13. Monitoring of pre-frontal oxygen status in helicopter pilots using near-infrared spectrophotometers

    PubMed Central

    Kikukawa, Azusa; Kobayashi, Asao; Miyamoto, Yoshinori

    2008-01-01

    Background There are few in-flight studies of cognition-related cerebral oxygen status in helicopter pilots. Methods Four male helicopter pilots volunteered for nine sorties during visual flight in a BK117 and UH-60J. The pilots' pre-frontal oxy-hemoglobin (O2Hb) and deoxy-hemoglobin (HHb) concentration were continuously monitored from the right/left sections of the forehead using near-infrared spectrophotometers with a consideration of motion artifacts. Results The concentration of O2Hb progressively increased (13.98 μmol•L-1 as a maximum increased concentration) in both the right/left sections of the forehead from the basal level during the heightened cognitive demand of helicopter flight. There was comparatively little change (4.32 μmol•L-1 as a maximum increased concentration) in HHb concentration during measurement of helicopter flight. HHb changes were apparently not affected by a heightened cognitive demand of helicopter pilots. Conclusion These results demonstrate that near-infrared spectroscopy, especially O2Hb measurements, provides a sensitive method for the monitoring of cognitive demand (maneuvers) in helicopter pilots. PMID:18616829

  14. Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions

    PubMed Central

    Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

    2016-01-01

    On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology–fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01–0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics. PMID:27352840

  15. Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

    2016-06-01

    On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology–fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01–0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics.

  16. Outdoor solar UVA dose assessment with EBT2 radiochromic film using spectrophotometer and densitometer measurements.

    PubMed

    Abukassem, I; Bero, M A

    2015-04-01

    Direct measurements of solar ultraviolet radiations (UVRs) have an important role in the protection of humans against UVR hazard. This work presents simple technique based on the application of EBT2 GAFCHROMIC(®) film for direct solar UVA dose assessment. It demonstrates the effects of different parts of the solar spectrum (UVB, visible and infrared) on performed UVA field measurements and presents the measurement uncertainty budget. The gradient of sunlight exposure level permitted the authors to establish the mathematical relationships between the measured solar UVA dose and two measured quantities: the first was the changes in spectral absorbance at the wavelength 633 nm (A633) and the second was the optical density (OD). The established standard relations were also applied to calculate the solar UVA dose variations during the whole day; 15 min of exposure each hour between 8:00 and 17:00 was recorded. Results show that both applied experimental methods, spectrophotometer absorbance and densitometer OD, deliver comparable figures for EBT2 solar UVA dose assessment with relative uncertainty of 11% for spectral absorbance measurements and 15% for OD measurements. PMID:25500756

  17. Euclid near infrared spectrophotometer instrument concept and first test results at the end of phase B

    NASA Astrophysics Data System (ADS)

    Maciaszek, Thierry; Ealet, Anne; Jahnke, Knud; Prieto, Eric; Barbier, Rémi; Mellier, Yannick; Costille, Anne; Ducret, Franck; Fabron, Christophe; Gimenez, Jean-Luc; Grange, Robert; Martin, Laurent; Rossin, Christelle; Pamplona, Tony; Vola, Pascal; Clémens, Jean Claude; Smadja, Gérard; Amiaux, Jérome; Barrière, Jean Christophe; Berthe, Michel; De Rosa, Adriano; Franceschi, Enrico; Morgante, Gianluca; Trifoglio, Massimo; Valenziano, Luca; Bonoli, Carlotta; Bortoletto, Favio; D'Alessandro, Maurizio; Corcione, Leonardo; Ligori, Sebastiano; Garilli, Bianca; Riva, Marco; Grupp, Frank; Vogel, Carolin; Hormuth, Felix; Seidel, Gregor; Wachter, Stefanie; Diaz, Jose Javier; Grañena, Ferran; Padilla, Cristobal; Toledo, Rafael; Lilje, Per B.; Solheim, Bjarte G. B.; Toulouse-Aastrup, Corinne; Andersen, Michael; Holmes, Warren; Israelsson, Ulf; Seiffert, Michael; Weber, Carissa; Waczynski, Augustyn; Laureijs, René J.; Racca, Giuseppe; Salvignol, Jean-Christophe; Strada, Paolo

    2014-08-01

    The Euclid mission objective is to understand why the expansion of the Universe is accelerating by mapping the geometry of the dark Universe by investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision program with its launch planned for 2020. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (0.9-2μm) as a photometer and spectrometer. The instrument is composed of: - a cold (135K) optomechanical subsystem consisting of a SiC structure, an optical assembly (corrector and camera lens), a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG cooled to 95K with their front-end readout electronic cooled to 140K, integrated on a mechanical focal plane structure made with Molybdenum and Aluminum. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data This presentation describes the architecture of the instrument at the end of the phase B (Preliminary Design Review), the expected performance, the technological key challenges and preliminary test results obtained on a detection system demonstration model.

  18. Improved retrieval of nitrogen dioxide (NO2) column densities by means of MKIV Brewer spectrophotometers

    NASA Astrophysics Data System (ADS)

    Diémoz, H.; Siani, A. M.; Redondas, A.; Savastiouk, V.; McElroy, C. T.

    2014-07-01

    A new algorithm to retrieve nitrogen dioxide (NO2) column densities using MKIV Brewer spectrophotometers is described. The method includes several improvements, such as a more recent spectroscopic dataset, the reduction of the measurement noise and interferences by other atmospheric species and instrumental settings, and a better determination of the air mass enhancement factors. The technique was tested during an ad-hoc calibration campaign at the high-altitude site of Izaña (Tenerife, Spain) and provided results compatible to those obtained from a spectrometer associated to the Network for the Detection of Atmospheric Composition Change (NDACC), with deviations of less than 0.02 DU. To determine the extraterrestrial constant, an easily implementable generalisation of the standard Langley technique was developed which takes into account the daytime linear drift of nitrogen dioxide due to the photochemistry. Estimates obtained from different observation geometries, by collecting the light from either the sun or the zenith sky, were found to be comparable within the measurement uncertainty. The latter was thoroughly determined by using a Monte Carlo technique. Finally, a method to retrieve additional products such as the degree of linear polarisation of the zenith sky and the oxygen dimer optical depth is presented. The new algorithm is backward-compatible, thus allowing for the reprocessing of historical datasets.

  19. The Soft X-ray Spectrophotometer SphinX for the CORONAS-Photon Mission

    NASA Astrophysics Data System (ADS)

    Sylwester, Janusz; Kowalinski, Miroslaw; Szymon, Gburek; Bakala, Jaroslaw; Kuzin, Sergey; Kotov, Yury; Farnik, Frantisek; Reale, Fabio

    The purpose, construction details and calibration results of the new design, Polish-led solar X-ray spectrophotometer SphinX will be presented. The instrument constitutes a part of the Russian TESIS X-ray and EUV complex aboard the forthcoming CORONAS-Photon solar mission to be launched later in 2008. SphinX uses Si-PIN detectors for high time resolution (down to 0.01 s) measurements of solar spectra in the energy range between 0.5 keV and 15 keV. The spectral resolution allows separating 256 individual energy channels in this range with particular groups of lines clearly distinguishable. Unprecedented accuracy of the instrument calibration at the XACT (Palermo) and BESSY (Berlin) synchrotron will allow for establishing the solar soft X-ray photometric reference system. The cross-comparison between SphinX and the other instruments presently in orbit like XRT on Hinode, RHESSI and GOES X-ray monitor, will allow for a precise determination of the coronal emission measure and temperature during both very low and very high activity periods. Examples of the detectors' ground calibration results as well as the calculated synthetic spectra will be presented. The operation of the instrument while in orbit will be discussed allowing for suggestions from other groups to be still included in mission planning.

  20. Optofluidic UV-Vis spectrophotometer for online monitoring of photocatalytic reactions.

    PubMed

    Wang, Ning; Tan, Furui; Zhao, Yu; Tsoi, Chi Chung; Fan, Xudong; Yu, Weixing; Zhang, Xuming

    2016-06-29

    On-chip integration of optical detection units into the microfluidic systems for online monitoring is highly desirable for many applications and is also well in line with the spirit of optofluidics technology-fusion of optics and microfluidics for advanced functionalities. This paper reports the construction of a UV-Vis spectrophotometer on a microreactor, and demonstrates the online monitoring of the photocatalytic degradations of methylene blue and methyl orange under different flow rates and different pH values by detecting the intensity change and/or the peak shift. The integrated device consists of a TiO2-coated glass substrate, a PDMS micro-sized reaction chamber and two flow cells. By comparing with the results of commercial equipment, we have found that the measuring range and the sensitivity are acceptable, especially when the transmittance is in the range of 0.01-0.9. This integrated optofluidic device can significantly cut down the test time and the sample volume, and would provide a versatile platform for real-time characterization of photochemical performance. Moreover, its online monitoring capability may enable to access the usually hidden information in biochemical reactions like intermediate products, time-dependent processes and reaction kinetics.

  1. Unconsciously elicited perceptual prior

    PubMed Central

    Chang, Raymond; Baria, Alexis T.; Flounders, Matthew W.; He, Biyu J.

    2016-01-01

    Increasing evidence over the past decade suggests that vision is not simply a passive, feed-forward process in which cortical areas relay progressively more abstract information to those higher up in the visual hierarchy, but rather an inferential process with top-down processes actively guiding and shaping perception. However, one major question that persists is whether such processes can be influenced by unconsciously perceived stimuli. Recent psychophysics and neuroimaging studies have revealed that while consciously perceived stimuli elicit stronger responses in higher visual and frontoparietal areas than those that fail to reach conscious awareness, the latter can still drive high-level brain and behavioral responses. We investigated whether unconscious processing of a masked natural image could facilitate subsequent conscious recognition of its degraded counterpart (a black-and-white “Mooney” image) presented many seconds later. We found that this is indeed the case, suggesting that conscious vision may be influenced by priors established by unconscious processing of a fleeting image. PMID:27595010

  2. Comparison of Ozone Retrievals from the Pandora Spectrometer System and Dobson Spectrophotometer in Boulder, Colorado

    NASA Technical Reports Server (NTRS)

    Herman, J.; Evans, R.; Cede, A.; Abuhassan, N.; Petropavlovskikh, I.; McConville, G.

    2015-01-01

    A comparison of retrieved total column ozone (TCO) amounts between the Pandora #34 spectrometer system and the Dobson #061 spectrophotometer from direct-sun observations was performed on the roof of the Boulder, Colorado, NOAA building. This paper, part of an ongoing study, covers a 1-year period starting on 17 December 2013. Both the standard Dobson and Pandora TCO retrievals required a correction, TCO(sub corr) = TCO (1 + C(T)), using a monthly varying effective ozone temperature, T(sub E), derived from a temperature and ozone profile climatology. The correction is used to remove a seasonal difference caused by using a fixed temperature in each retrieval algorithm. The respective corrections C(T(sub E)) are C(sub Pandora) = 0.00333(T(sub E) - 225) and C(sub Dobson) = -0.0013(T(sub E) - 226.7) per degree K. After the applied corrections removed most of the seasonal retrieval dependence on ozone temperature, TCO agreement between the instruments was within 1% for clear-sky conditions. For clear-sky observations, both co-located instruments tracked the day-to-day variation in total column ozone amounts with a correlation of r(exp 2) = 0.97 and an average offset of 1.1 +/- 5.8 DU. In addition, the Pandora TCO data showed 0.3% annual average agreement with satellite overpass data from AURA/OMI (Ozone Monitoring Instrument) and 1% annual average offset with Suomi-NPP/OMPS (Suomi National Polar-orbiting Partnership, the nadir viewing portion of the Ozone Mapper Profiler Suite).

  3. Retrieval of aerosol optical depth in the visible range with a Brewer spectrophotometer in Athens

    NASA Astrophysics Data System (ADS)

    Diémoz, Henri; Eleftheratos, Kostas; Kazadzis, Stelios; Amiridis, Vassilis; Zerefos, Christos S.

    2016-04-01

    A MkIV Brewer spectrophotometer has been operating in Athens since 2004. Direct-sun measurements originally scheduled for nitrogen dioxide retrievals were reprocessed to provide aerosol optical depths (AODs) at a wavelength of about 440 nm. A novel retrieval algorithm was specifically developed and the resulting AODs were compared to those obtained from a collocated Cimel filter radiometer belonging to the Aerosol Robotic Network (AERONET). The series are perfectly correlated, with Pearson's correlation coefficients being as large as 0.996 and with 90 % of AOD deviations between the two instruments being within the World Meteorological Organisation (WMO) traceability limits. In order to reach such a high agreement, several instrumental factors impacting the quality of the Brewer retrievals must be taken into account, including sensitivity to the internal temperature, and the state of the external optics and pointing accuracy must be carefully checked. Furthermore, the long-term radiometric stability of the Brewer was investigated and the performances of in situ Langley extrapolations as a way to track the absolute calibration of the Brewer were assessed. Other sources of error, such as slight shifts of the wavelength scale, are discussed and some recommendations to Brewer operators are drawn. Although MkIV Brewers are rarely employed to retrieve AODs in the visible range, they represent a key source of information about aerosol changes in the past three decades and a potential worldwide network for present and future coordinated AOD measurements. Moreover, a better understanding of the AOD retrieval at visible wavelengths will also contribute in improving similar techniques in the more challenging UV range.

  4. Unprecedented 1993 ozone decrease over the United States from Dobson spectrophotometer observations

    SciTech Connect

    Komhyr, W.D.; Grass, R.D.; Evans, R.D.; Leonard, R.K.; Quincy, D.M. ); Hoffman, D.J.; Koenig, G.L. )

    1994-02-01

    Dobson spectrophotometer observations conducted since the early-to-mid 1960's at Bismarck, North Dakota; Caribou, Maine; Boulder, Colorado; Wallops Island, Virginia; Nashville, Tennessee; and at Fresno, California, since 1983, have revealed record low total ozone values during 1993. The tendency toward the low ozone values began in May 1992, but accelerated in early 1993. During January-August 1993, ozone monthly means at the stations were more than 2 standard deviations below long-term normal monthly means 72% of the time and more than 3 standard deviations below normals 42% of the time. On average, the January-April 1993 ozone values were 12.6% below normal, with ozone deficits as large as 18% observed at Caribou and Wallops Island in January. Of particular concern are unusually low ozone values that occur in summertime when solar ultraviolet insolation is high. Such record lows occurred at four of the six stations (Caribou, Wallops Island, Fresno, and Nashville). During May-August 1993, ozone was on average 8.5% below normal at these sites. Monthly means at these stations were, furthermore, lower on average by 3.7% than corresponding lowest values observed there in the past. The ozone decrease of 12.6% below normal at the six continental Dobson instrument stations during the winter and spring months of 1993 implies a possible average increase in UV erythemal radiation at that time of 16-25% above normal. The 8.5% decrease in ozone at Caribou, Wallops Island, Fresno, and Nashville, implies that on average, UV erythemal radiation may have been higher than normal at these stations during the summer of 1993 by 11-17%. 5 refs., 3 figs., 1 tab.

  5. Status report and FY95 plans -- Re-evaluation of NOAA Dobson spectrophotometer total ozone data. 1994 annual report

    SciTech Connect

    1994-12-31

    The goal of this project was to re-evaluate NOAA/CMDL Dobson spectrophotometer total ozone data during FY94 from the stations Haute Provence, France; Lauder, New Zealand; Perth, Australia; and Poker Flat, Alaska and the Umkehr data from Boulder, Colorado and Mauna Loa, Hawaii. During the second year the authors planned to re-evaluate total ozone data from Byrd, Hallett and South Pole, Antarctica; Fairbanks, Alaska; Puerto Montt, Chile; Huancayo, Peru and Umkehr data from Huancayo.

  6. The impact of the ozone effective temperature on satellite validation using the Dobson spectrophotometer network

    NASA Astrophysics Data System (ADS)

    Elissavet Koukouli, Maria; Zara, Marina; Lerot, Christophe; Fragkos, Konstantinos; Balis, Dimitris; van Roozendael, Michel; Antonius Franciscus Allart, Marcus; van der A, Ronald Johannes

    2016-05-01

    The main aim of the paper is to demonstrate an approach for post-processing of the Dobson spectrophotometers' total ozone columns (TOCs) in order to compensate for their known stratospheric effective temperature (Teff) dependency and its resulting effect on the usage of the Dobson TOCs for satellite TOCs' validation. The Dobson observations employed are those routinely submitted to the World Ozone and Ultraviolet Data Centre (WOUDC) of the World Meteorological Organization, whereas the effective temperatures have been extracted from two sources: the European Space Agency, ESA, Ozone Climate Change Initiative, Ozone-CCI, GODFIT version 3 (GOME-type Direct FITting) algorithm applied to the GOME2/MetopA, GOME2A, observations as well as the one derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) outputs. Both temperature sources are evaluated utilizing co-located ozonesonde measurements also retrieved from the WOUDC database. Both GODFIT_v3 and ECMWF Teffs are found to be unbiased against the ozonesonde observations and to agree with high correlation coefficients, especially for latitudes characterized by high seasonal variability in Teff. The validation analysis shows that, when applying the GODFIT_v3 effective temperatures in order to post-process the Dobson TOC, the mean difference between Dobson and GOME2A GODFIT_v3 TOCs moves from 0.63 ± 0.66 to 0.26 ± 0.46 % in the Northern Hemisphere and from 1.25 ± 1.20 to 0.80 ± 0.71 % in the Southern Hemisphere. The existing solar zenith angle dependency of the differences has been smoothed out, with near-zero dependency up to the 60-65° bin and the highest deviation decreasing from 2.38 ± 6.6 to 1.37 ± 6.4 % for the 80-85° bin. We conclude that the global-scale validation of satellite TOCs against collocated Dobson measurements benefits from a post-correction using suitably estimated Teffs.

  7. Determining CDOM Absorption Spectra in Diverse Aquatic Environments Using a Multiple Pathlength, Liquid Core Waveguide System

    NASA Technical Reports Server (NTRS)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2001-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, aCDOM, and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values and showed a linear response across all four pathlengths. Values of aCDOM measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of aCDOM for MPLCW measurements was 0.002 - 231.5 m-1. At low CDOM concentrations spectrophotometric aCDOM were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples.

  8. Menarche: Prior Knowledge and Experience.

    ERIC Educational Resources Information Center

    Skandhan, K. P.; And Others

    1988-01-01

    Recorded menstruation information among 305 young women in India, assessing the differences between those who did and did not have knowledge of menstruation prior to menarche. Those with prior knowledge considered menarche to be a normal physiological function and had a higher rate of regularity, lower rate of dysmenorrhea, and earlier onset of…

  9. The Importance of Prior Knowledge.

    ERIC Educational Resources Information Center

    Cleary, Linda Miller

    1989-01-01

    Recounts a college English teacher's experience of reading and rereading Noam Chomsky, building up a greater store of prior knowledge. Argues that Frank Smith provides a theory for the importance of prior knowledge and Chomsky's work provided a personal example with which to interpret and integrate that theory. (RS)

  10. On-line process applications development using a fiber optic-based Hewlett-Packard 8452A spectrophotometer

    NASA Astrophysics Data System (ADS)

    Vetter, Hans; Ponstingl, Mike

    1995-01-01

    The introduction of fiber optic accessories for the Hewlett-Packard 8452A diode array spectrophotometer has greatly expanded its utility and, in particular, has enhanced its use as a process application development tool. There is a clear trend toward fiber optic based process photometric analyzers. With the advent of spectroscopy using fiber optics, the stage is set for a logical transition of laboratory developed applications to process implementation. This is particularly true when both the laboratory spectrophotometric and the process photometric analyzers are capable of using the same sensors. This paper presents an example of an application development and its transition to process implementation.

  11. On-line process applications development using a fiber-optic based Hewlett-Packard 8452A spectrophotometer

    SciTech Connect

    Vetter, H.; Ponstingl, M.

    1995-12-31

    The introduction of fiber optic accessories for the Hewlett-Packard 8452A diode array spectrophotometer has greatly expanded its utility and, in particular, has enhanced its use as a process application development tool. There is a clear trend toward fiber optic based process photometric analyzers. With the advent of spectroscopy using fiber optics, the stage is set for a logical transition of laboratory developed applications to process implementation. This is particularly true when both the laboratory spectrophotometric and the process photometric analyzers are capable of using the same sensors. This paper presents an example of an application development and its transition to process implementation.

  12. Comparison of UV-B measurements performed with a Brewer spectrophotometer and a new UVB-1 broad band detector

    NASA Technical Reports Server (NTRS)

    Bais, Alkiviadis F.; Zerefos, Christos S.; Meleti, Charicleia; Ziomas, Ioannis C.

    1994-01-01

    Measurements of the UV-B erythemal dose, based on solar spectra acquired with a Brewer spectrophotometer at Thessaloniki, Greece, are compared to measurements performed with the recently introduced, by the Yankee Environmental Systems, (Robertson type) broad band solar UV-B detector. The spectral response function of this detector, when applied to the Brewer spectral UV-B measurements, results in remarkably comparable estimates of the erythemal UV-B dose. The two instruments provide similar information on the UV-B dose when they are cross-examined under a variety of meteorological and atmospheric conditions and over the a large range of solar zenith angles and total ozone.

  13. Water Quality Data at High Time and Space Resolution in the Field : Expanding Spectrophotometer Capabilities with Arduino Driven Autosamplers

    NASA Astrophysics Data System (ADS)

    Birgand, F.; Maxwell, B.; Aveni-Deforge, K.; Etheridge, R.

    2014-12-01

    Availability of continuous hydrological data (e.g. flow rates, rainfall, etc.) for over a century has shaped our current understanding of the hydrological cycle. Until now, there has been no equivalence for water quality. Optics based systems now open the possibility to obtain data at a temporal resolution in par with that commonly used in quantitative hydrology (e.g. 15 min - 1 hr). We show that absorbance measured in the field using spectrophotometers can be statistically correlated with light- and none- absorbing constituents in the water. Water quality rating curves for 6-12 parameters can be derived as such using a single spectrophotometer, opening access to continuous water quality data for many parameters at a time. We then show that attaching such probe in the field with multiplexed pumping systems driven by Arduinos can expand the high temporal resolution capabilities to space as our systems can sample up to 12 different water sources located within 15 m of the water quality probe.

  14. The Use of a Microprocessor-Controlled, Video Output Atomic Absorption Spectrometer as an Educational Tool in a Two-Year Technical Curriculum.

    ERIC Educational Resources Information Center

    Kerfoot, Henry B.

    Based on instructional experiences at Charles County Community College, Maryland, this report examines the pedagogical advantage of teaching atomic absorption (AA) spectroscopy with an AA spectrophotometer that is equipped with a microprocessor and video output mechanism. The report first discusses the growing importance of AA spectroscopy in…

  15. THE ABSORPTION SPECTRUM OF VISUAL PURPLE

    PubMed Central

    Chase, Aurin M.; Haig, Charles

    1938-01-01

    The absorption spectra of visual purple solutions extracted by various means were measured with a sensitive photoelectric spectrophotometer and compared with the classical visual purple absorption spectrum. Hardening the retinas in alum before extraction yielded visual purple solutions of much higher light transmission in the blue and violet, probably because of the removal of light-dispersing substances. Re-extraction indicated that visual purple is more soluble in the extractive than are the other colored retinal components. However, the concentration of the extractive did not affect the color purity of the extraction but did influence the keeping power. This suggests a chemical combination between the extractive and visual purple. The pH of the extractive affected the color purity of the resulting solution. Over the pH range from 5.5 to 10.0, the visual purple color purity was greatest at the low pH. Temperature during extraction was also effective, the color purity being greater the higher the temperature, up to 40°C. Drying and subsequent re-dissolving of visual purple solutions extracted with digitalin freed the solution of some protein impurities and increased its keeping power. Dialysis against distilled water seemed to precipitate visual purple from solution irreversibly. None of the treatments described improved the symmetry of the unbleached visual purple absorption spectrum sufficiently for it to resemble the classical absorption spectrum. Therefore it is very likely that the classical absorption spectrum is that of the light-sensitive group only and that the absorption spectra of our purest unbleached visual purple solutions represent the molecule as a whole. PMID:19873058

  16. Measurements of Nitrogen Dioxide Total Column Amounts using a Brewer Double Spectrophotometer in Direct Sun Mode

    NASA Technical Reports Server (NTRS)

    Cede, Alexander; Herman, Jay; Richter, Andreas; Krotkov, Nickolay; Burrows, John

    2006-01-01

    NO2 column amounts were measured for the past 2 years at Goddard Space Flight Center, Greenbelt, Maryland, using a Brewer spectrometer in direct Sun mode. A new bootstrap method to calibrate the instrument is introduced and described. This technique selects the cleanest days from the database to obtain the solar reference spectrum. The main advantage for direct Sun measurements is that the conversion uncertainty from slant column to vertical column is negligible compared to the standard scattered light observations where it is typically on the order of 100% (2sigma) at polluted sites. The total 2sigma errors of the direct Sun retrieved column amounts decrease with solar zenith angle and are estimated at 0.2 to 0.6 Dobson units (DU, 1 DU approx. equal to 2.7 10(exp 16) molecules cm(exp -2)), which is more accurate than scattered light measurements for high NO2 amounts. Measured NO2 column amounts, ranging from 0 to 3 DU with a mean of 0.7 DU, show a pronounced daily course and a strong variability from day to day. The NO2 concentration typically increases from sunrise to noon. In the afternoon it decreases in summer and stays constant in winter. As expected from the anthropogenic nature of its source, NO2 amounts on weekends are significantly reduced. The measurements were compared to satellite retrievals from Scanning Image Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). Satellite data give the same average NO2 column and show a seasonal cycle that is similar to the ground data in the afternoon. We show that NO2 must be considered when retrieving aerosol absorption properties, especially for situations with low aerosol optical depth.

  17. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  18. Signal-to-noise optimization and evaluation of a home-made visible diode-array spectrophotometer

    PubMed Central

    Raimundo, Jr., Ivo M.; Pasquini, Celio

    1993-01-01

    This paper describes a simple low-cost multichannel visible spectrophotometer built with an RL512G EGG-Reticon photodiode array. A symmetric Czerny-Turner optical design was employed; instrument control was via a single-board microcomputer based on the 8085 Intel microprocessor. Spectral intensity data are stored in the single-board's RAM and then transferred to an IBM-AT 3865X compatible microcomputer through a RS-232C interface. This external microcomputer processes the data to recover transmittance, absorbance or relative intensity of the spectra. The signal-to-noise ratio and dynamic range were improved by using variable integration times, which increase during the same scan; and by the use of either weighted or unweighted sliding average of consecutive diodes. The instrument is suitable for automatic methods requiring quasi-simultaneous multiwavelength detections, such as multivariative calibration and flow-injection gradient scan techniques. PMID:18924979

  19. Re-evaluation of total and Umkehr ozone data from NOAA-CMDL Dobson spectrophotometer observatories. Final report

    SciTech Connect

    Komhyr, W.D.; Quincy, D.M.; Grass, R.D.; Koenig, G.L. |

    1995-12-01

    This report describes work to improve the quality of total ozone and Umkehr data obtained in the past at the NOAA Climate Monitoring and Diagnostics Laboratory and the Dobson spectrophotometer ozone observatories. The authors present results of total ozone data re-evaluations for ten stations: Byrd, Antarctica; Fairbanks, Alaska; Hallett, Antarctica; Huancayo, Peru; Haute Provence, France; Lauder, New Zealand; Perth, Australia; Poker Flat, Alaska; Puerto Montt, Chile; and South Pole, Antarctica. The improved data will be submitted in early 1996 to the World Meteorological Organization (WMO) World Ozone Data Center (WODC), and the Atmospheric Environment Service for archiving. Considerable work has been accomplished, also, in reevaluating Umkehr data from seven of the stations, viz., Huancayo, Haute Provence, Lauder, Perth, Poker Flat, Boulder, Colorado; and Mauna Loa, Hawaii.

  20. A New High-sensitivity solar X-ray Spectrophotometer SphinX:early operations and databases

    NASA Astrophysics Data System (ADS)

    Gburek, Szymon; Sylwester, Janusz; Kowalinski, Miroslaw; Siarkowski, Marek; Bakala, Jaroslaw; Podgorski, Piotr; Trzebinski, Witold; Plocieniak, Stefan; Kordylewski, Zbigniew; Kuzin, Sergey; Farnik, Frantisek; Reale, Fabio

    The Solar Photometer in X-rays (SphinX) is an instrument operating aboard Russian CORONAS-Photon satellite. A short description of this unique instrument will be presented and its unique capabilities discussed. SphinX is presently the most sensitive solar X-ray spectrophotometer measuring solar spectra in the energy range above 1 keV. A large archive of SphinX mea-surements has already been collected. General access to these measurements is possible. The SphinX data repositories contain lightcurves, spectra, and photon arrival time measurements. The SphinX data cover nearly continuously the period since the satellite launch on January 30, 2009 up to the end-of November 2009. Present instrument status, data formats and data access methods will be shown. An overview of possible new science coming from SphinX data analysis will be discussed.

  1. Normal incidence spectrophotometer using high density transmission grating technology and highly efficiency silicon photodiodes for absolute solar EUV irradiance measurements

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Mcmullin, D.; Judge, D. L.; Korde, R.

    1992-01-01

    New developments in transmission grating and photodiode technology now make it possible to realize spectrometers in the extreme ultraviolet (EUV) spectral region (wavelengths less than 1000 A) which are expected to be virtually constant in their diffraction and detector properties. Time dependent effects associated with reflection gratings are eliminated through the use of free standing transmission gratings. These gratings together with recently developed and highly stable EUV photodiodes have been utilized to construct a highly stable normal incidence spectrophotometer to monitor the variability and absolute intensity of the solar 304 A line. Owing to its low weight and compactness, such a spectrometer will be a valuable tool for providing absolute solar irradiance throughout the EUV. This novel instrument will also be useful for cross-calibrating other EUV flight instruments and will be flown on a series of Hitchhiker Shuttle Flights and on SOHO. A preliminary version of this instrument has been fabricated and characterized, and the results are described.

  2. Total ozone derived from UV spectrophotometer measurements on the NASA CV-990 aircraft for the fall 1976 latitude survey flights

    NASA Technical Reports Server (NTRS)

    Hanser, F. A.

    1977-01-01

    An ultraviolet interference filter spectrophotometer was modified to use a photodiode and was flown on latitude survey flights in the fall of 1976. Comparison with Dobson station total ozone values shows agreement between UVS and Dobson total ozone of + or - 2 percent. The procedure used to convert UVS measured ozone above the aircraft altitude to total ozone above ground level introduces an additional 2 percent deviation for very high altitude UVS ozone data. Under stable aircraft operating conditions, the UVS derived ozone values have a variability, or reproducibility, of better than + or -1 percent. The UVS data from the latitude survey flights yield a detailed latitude profile of total ozone over the Pacific Ocean during November 1976. Significant latitudinal structure in total ozone is found at the middle latitudes (30 deg to 40 deg N and S).

  3. Indication of a Near Surface Cloud Layer on Venus from Reanalysis of Venera 13/14 Spectrophotometer Data

    NASA Astrophysics Data System (ADS)

    Grieger, B.; Ignatiev, N.; Hoekzema, N.; Keller, H. U.

    2003-12-01

    In 1982, Venera 13 and 14 reached the surface of Venus as the last, most developed probes of the Venera lander series. During the descent, the spec\\-tro\\-pho\\-to\\-me\\-ter measured the radiance inside the atmosphere at different directions and wavelengths. In January 2005, the Descent Imager/Spectral Radiometer (DISR) on board the Huygens probe will make similar observations --- albeit at higher spatial and spectral resolution --- during its descent through Titan's atmosphere. To retrieve the optical properties from DISR data, the Titan Inverse Radiation Model ({\\sf T!RM}) has been developed. Deep in an optically thick atmosphere like Venus', the volume extinction coefficient can approximately be estimated from zenith and nadir radiances. The respective analysis of Venera spectrophotometer data at high vertical resolution yields a pronounced peak of extinction 1--2 km above the surface of Venus. To check wether this peak could be an artefact due to the neglection of the near surface in the analytical approximation applied, we alternatively reconstruct the extinction profile with {\\sf T!RM}. The radiative transfer computations imply assimilation of Venera 14 measurements at 705 nm and take into account the surface considering different albedo values. The modeled extinction profiles differ only marginally from the analytical approximation (cf. figure), supporting the indication of a pronounced layer of increased extinction, possibly due to clouds. The peak 1--2 km above the surface shows also up for Venera 13 data and over the complete observed wavelength range of 480--1140 nm. This work was supported by the German Aerospace Center (DLR), contract number 50 OH 98044.

  4. Modified calibration procedures for a Yankee Environmental System UVB-1 biometer based on spectral measurements with a brewer spectrophotometer.

    PubMed

    Vilaplana, José M; Cachorro, Victoria E; Sorribas, Mar; Luccini, Eduardo; de Frutos, Angel M; Berjón, Alberto; de la Morena, Benito

    2006-01-01

    The calibration of the erythemal irradiance measured by a Yankee Environmental System (YES) UVB-1 biometer is presented using two methods of calibration with a wide range of experimental solar zenith angles (SZAs) and ozone values. The calibration is performed through simultaneous spectral measurements by a calibrated double-monochromator Brewer MK-III spectrophotometer at "El Arenosillo" station, located in southwestern Spain. Because the range of spectral measurements of the Brewer spectrophotometer is 290-363 nm, a previously validated radiative transfer model was used to account for the erythemal contribution between 363 and 400 nm. Both methods are recommended by the World Meteorological Organization and we present and discuss here a wide range of results and features given by modified procedures applied to these two general methods. As is well established, the calibration factor for this type of radiometric system is dependent on atmospheric conditions, the most important of which are the ozone content and the SZA. Although the first method is insensitive to these two factors, we analyze this behavior in terms of the range used for the SZA and the use of two different mathematical approaches for its determination. The second method shows the dependence on SZA and ozone content and, thus, a polynomial as a function of SZA or a matrix including SZA and ozone content were determined as general calibration factors for the UV radiometric system. We must note that the angular responses of the YES radiometer and Brewer spectroradiometer have not been considered, because of the difficulty in correcting them. The results show in detail the advantages and drawbacks (and the corresponding associated error) given by the different approaches used for the determination of these calibration coefficients.

  5. Components of Visual Prior Entry

    ERIC Educational Resources Information Center

    Schneider, Keith A.; Bavelier, Daphne

    2003-01-01

    The prior entry hypothesis contends that attention accelerates sensory processing, shortening the time to perception. Typical observations supporting the hypothesis may be explained equally well by response biases, changes in decision criteria, or sensory facilitation. In a series of experiments conducted to discriminate among the potential…

  6. Prior Distributions on Symmetric Groups

    ERIC Educational Resources Information Center

    Gupta, Jayanti; Damien, Paul

    2005-01-01

    Fully and partially ranked data arise in a variety of contexts. From a Bayesian perspective, attention has focused on distance-based models; in particular, the Mallows model and extensions thereof. In this paper, a class of prior distributions, the "Binary Tree," is developed on the symmetric group. The attractive features of the class are: it…

  7. Measurement of solutes in dialysate using UV absorption

    NASA Astrophysics Data System (ADS)

    Fridolin, Ivo; Magnusson, Martin; Lindberg, Lars-Goeran

    2001-06-01

    The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in by-pass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).

  8. [Determination of copper, magnesium and zinc in mononuclear leukocytes by flame atomic absorption spectrometry].

    PubMed

    Rahn-Chique, Kareem; Carrión, Nereida; Murillo, Miguel

    2012-12-01

    In this paper we evaluated a new micro-flow injector for the determination of the concentrations of Cu, Mg and Zn in mononuclear blood cells. This device analyzed sample volumes in the order of microliters by flame atomic absorption spectrometry; it is inexpensive, and easy to build and to adapt to the conventional injector of the atomic absorption spectrophotometer. Detection limits of 106, 65 and 37 microg L(-1) for Cu, Mg and Zn were obtained, respectively. The percentages of recovery tests were found between 98 and 110%. PMID:23513485

  9. Predicting a prior for Planck

    SciTech Connect

    Hertog, Thomas

    2014-02-01

    The quantum state of the universe combined with the structure of the landscape potential implies a prior that specifies predictions for observations. We compute the prior for CMB related observables given by the no-boundary wave function (NBWF) in a landscape model that includes a range of inflationary patches representative of relatively simple single-field models. In this landscape the NBWF predicts our classical cosmological background emerges from a region of eternal inflation associated with a plateau-like potential. The spectra of primordial fluctuations on observable scales are characteristic of concave potentials, in excellent agreement with the Planck data. By contrast, alternative theories of initial conditions that strongly favor inflation at high values of the potential are disfavored by observations in this landscape.

  10. X-ray spectrophotometer SphinX and particle spectrometer STEP-F of the satellite experiment CORONAS-PHOTON. Preliminary results of the joint data analysis

    NASA Astrophysics Data System (ADS)

    Dudnik, O. V.; Podgorski, P.; Sylwester, J.; Gburek, S.; Kowalinski, M.; Siarkowski, M.; Plocieniak, S.; Bakala, J.

    2012-04-01

    A joint analysis is carried out of data obtained with the help of the solar X-ray SphinX spectrophotometer and the electron and proton satellite telescope STEP-F in May 2009 in the course of the scientific space experiment CORONAS-PHOTON. In order to determine the energies and particle types, in the analysis of spectrophotometer records data are used on the intensities of electrons, protons, and secondary γ-radiation, obtained by the STEP-F telescope, which was located in close proximity to the SphinX spectrophotometer. The identical reaction of both instruments is noted at the intersection of regions of the Brazilian magnetic anomaly and the Earth's radiation belts. It is shown that large area photodiodes, serving as sensors of the X-ray spectrometer, reliably record electron fluxes of low and intermediate energies, as well as fluxes of the secondary gamma radiation from construction materials of detector modules, the TESIS instrument complex, and the spacecraft itself. The dynamics of electron fluxes, recorded by the SphinX spectrophotometer in the vicinity of a weak geomagnetic storm, supplements the information about the processes of radial diffusion of electrons, which was studied using the STEP-F telescope.

  11. Development of mixed-waste analysis capability for graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Bass, D.A.; TenKate, L.B.; Wroblewski, A.

    1995-03-01

    Graphite furnace atomic absorption spectrophotometer (GFAAS) are typically configured with ventilation to capture potentially toxic and corrosive gases emitted from the vaporization of sample aliquots. When radioactive elements are present, additional concerns (such as meeting safety guidelines and ALARA principles) must be addressed. This report describes a modification to a GFAAS that provides additional containment of vaporized sample aliquots. The modification was found to increase containment by a factor of 80, given expected operating conditions. The use of the modification allows more mixed-waste samples to be analyzed, permits higher levels of radioactive samples to be analyzed, or exposes the analyst to less airborne radioactivity. The containment apparatus was attached to a Perkin-Elmer Zeeman 5000 spectrophotometer for analysis of mixed-waste samples; however, it could also be used on other systems and in other applications where greater containment of vaporized material is desired.

  12. An improved algorithm for the determination of aerosol optical depth in the ultraviolet spectral range from Brewer spectrophotometer observations

    NASA Astrophysics Data System (ADS)

    Sellitto, P.; di Sarra, A.; Siani, A. M.

    2006-10-01

    Methods to derive aerosol optical depth in the UV spectral range from ground-based remote-sensing stations equipped with Brewer spectrophotometers have been recently developed. In this study a modified Langley plot method has been implemented to retrieve aerosol optical depth from direct sun Brewer measurements. The method uses measurements over an extended range of atmospheric airmasses obtained with two different neutral density filters, and accounts for short-term variations of total ozone, derived from the same direct sun observations. The improved algorithm has been applied to data collected with a Brewer mark IV, operational in Rome, Italy, and with a Brewer mark III, operational in Lampedusa, Italy, in the Mediterranean. The efficiency of the improved algorithm has been tested comparing the number of determinations of the extraterrestrial constant against those obtained with a standard Langley plot procedure. The improved method produces a larger number of reliable Langley plots, allowing for a better statistical characterization of the extraterrestrial constant and a better study of its temporal variability. The values of aerosol optical depth calculated in Rome and Lampedusa compare well with simultaneous determinations in the 416-440 nm interval derived from MFRSR and CIMEL measurements.

  13. Light absorption of organic aerosol from pyrolysis of corn stalk

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; Chen, Yanju; Bond, Tami C.

    2016-11-01

    Organic aerosol (OA) can absorb solar radiation in the low-visible and ultra-violet wavelengths thereby modifying radiative forcing. Agricultural waste burning emits a large quantity of organic carbon in many developing countries. In this work, we improved the extraction and analysis method developed by Chen and Bond, and extended the spectral range of OC absorption. We examined light absorbing properties of primary OA from pyrolysis of corn stalk, which is a major type of agricultural wastes. Light absorption of bulk liquid extracts of OA was measured using a UV-vis recording spectrophotometer. OA can be extracted by methanol at 95%, close to full extent, and shows polar character. Light absorption of organic aerosol has strong spectral dependence (Absorption Ångström exponent = 7.7) and is not negligible at ultra-violet and low-visible regions. Higher pyrolysis temperature produced OA with higher absorption. Imaginary refractive index of organic aerosol (kOA) is 0.041 at 400 nm wavelength and 0.005 at 550 nm wavelength, respectively.

  14. Absorptive Capacity: A New Perspective on Learning and Innovation.

    ERIC Educational Resources Information Center

    Cohen, Wesley M.; Levinthal, Daniel A.

    1990-01-01

    Argues that ability of a firm to recognize value of new, external information, assimilate it, and apply it to commercial ends is critical to its innovative capabilities. A firm's absorptive capacity is largely a function of its level of prior knowledge. A research and development investment model that contributes to a firm's absorptive capacity is…

  15. Quantitative filter technique measurements of spectral light absorption by aquatic particles using a portable integrating cavity absorption meter (QFT-ICAM).

    PubMed

    Röttgers, Rüdiger; Doxaran, David; Dupouy, Cecile

    2016-01-25

    The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows rapid measurements of a sample filter. The measurement technique takes into account artifacts due to chlorophyll-a fluorescence. The QFT-ICAM is shown to be highly comparable to similar measurements in laboratory spectrophotometers, in terms of accuracy, precision, and path length amplification effects. No spectral artifacts were observed when compared to measurement of samples in suspension, whereas freezing and storing of sample filters induced small losses of water-soluble pigments (probably phycoerythrins). Remaining problems in determining the particulate absorption coefficient with the QFT-ICAM are strong sample-to-sample variations of the path length amplification, as well as fluorescence by pigments that is emitted in a different spectral region than that of chlorophyll-a.

  16. Improved fiberoptic spectrophotometer

    DOEpatents

    Tans, P.P.; Lashof, D.A.

    1985-04-02

    The present invention allows for accurate spectrophotmetric comparison of the Raman scattering from a sample gas with the Raman scattering from a known gas via a novel fiber optic network. The need for complicated electronic of optical circuit balancing, control, or error compensation circuitry is eliminated. The laser cavity is split into two regions, one of which houses the plasma discharge and produces laser power, and the other of which is adapted to house tubes containing the gas samples. Light from the laser source is beamed simultaneously through samples of the reference gas and the unknown gas, and Raman-scattered light is emitted. The Raman-scattered light from the known and unknown mixtures is then alternately passed through a fiber optic network where the various wavelengths are spatially mixed. The mixed light is then passed into a system of light detectors, each of which are adapted to measure one of the wavelengths of light representing a constituent element of the gases. When the test is complete, each gas sample can be assigned a Raman-scattered profile from the data consisting of the ratios each of the constituent elements bear to each other. (LEW)

  17. An in-line spectrophotometer on a centrifugal microfluidic platform for real-time protein determination and calibration.

    PubMed

    Ding, Zhaoxiong; Zhang, Dongying; Wang, Guanghui; Tang, Minghui; Dong, Yumin; Zhang, Yixin; Ho, Ho-Pui; Zhang, Xuping

    2016-09-21

    In this paper, an in-line, low-cost, miniature and portable spectrophotometric detection system is presented and used for fast protein determination and calibration in centrifugal microfluidics. Our portable detection system is configured with paired emitter and detector diodes (PEDD), where the light beam between both LEDs is collimated with enhanced system tolerance. It is the first time that a physical model of PEDD is clearly presented, which could be modelled as a photosensitive RC oscillator. A portable centrifugal microfluidic system that contains a wireless port in real-time communication with a smartphone has been built to show that PEDD is an effective strategy for conducting rapid protein bioassays with detection performance comparable to that of a UV-vis spectrophotometer. The choice of centrifugal microfluidics offers the unique benefits of highly parallel fluidic actuation at high accuracy while there is no need for a pump, as inertial forces are present within the entire spinning disc and accurately controlled by varying the spinning speed. As a demonstration experiment, we have conducted the Bradford assay for bovine serum albumin (BSA) concentration calibration from 0 to 2 mg mL(-1). Moreover, a novel centrifugal disc with a spiral microchannel is proposed for automatic distribution and metering of the sample to all the parallel reactions at one time. The reported lab-on-a-disc scheme with PEDD detection may offer a solution for high-throughput assays, such as protein density calibration, drug screening and drug solubility measurement that require the handling of a large number of reactions in parallel. PMID:27531134

  18. An in-line spectrophotometer on a centrifugal microfluidic platform for real-time protein determination and calibration.

    PubMed

    Ding, Zhaoxiong; Zhang, Dongying; Wang, Guanghui; Tang, Minghui; Dong, Yumin; Zhang, Yixin; Ho, Ho-Pui; Zhang, Xuping

    2016-09-21

    In this paper, an in-line, low-cost, miniature and portable spectrophotometric detection system is presented and used for fast protein determination and calibration in centrifugal microfluidics. Our portable detection system is configured with paired emitter and detector diodes (PEDD), where the light beam between both LEDs is collimated with enhanced system tolerance. It is the first time that a physical model of PEDD is clearly presented, which could be modelled as a photosensitive RC oscillator. A portable centrifugal microfluidic system that contains a wireless port in real-time communication with a smartphone has been built to show that PEDD is an effective strategy for conducting rapid protein bioassays with detection performance comparable to that of a UV-vis spectrophotometer. The choice of centrifugal microfluidics offers the unique benefits of highly parallel fluidic actuation at high accuracy while there is no need for a pump, as inertial forces are present within the entire spinning disc and accurately controlled by varying the spinning speed. As a demonstration experiment, we have conducted the Bradford assay for bovine serum albumin (BSA) concentration calibration from 0 to 2 mg mL(-1). Moreover, a novel centrifugal disc with a spiral microchannel is proposed for automatic distribution and metering of the sample to all the parallel reactions at one time. The reported lab-on-a-disc scheme with PEDD detection may offer a solution for high-throughput assays, such as protein density calibration, drug screening and drug solubility measurement that require the handling of a large number of reactions in parallel.

  19. Automatic gonio-spectrophotometer for the absolute measurement of the spectral BRDF at in- and out-of-plane and retroreflection geometries

    NASA Astrophysics Data System (ADS)

    Rabal, A. M.; Ferrero, A.; Campos, J.; Fontecha, J. L.; Pons, A.; Rubiño, A. M.; Corróns, A.

    2012-06-01

    This paper presents the description and the characterization of the gonio-spectrophotometer GEFE (the acronym for 'Gonio-EspectroFotómetro Español'). This device has been designed and built for the low-uncertainty absolute measurement of the bidirectional reflectance distribution function (BRDF). It comprises a fixed, collimated and uniform light source, a six-axis robot-arm to rotate the sample and a spectroradiometer that may revolve around the sample to be able to vary the source-to-detector angular separation. This gonio-spectrophotometer makes it possible to perform spectral measurements in the visible range, both inside and outside the incidence plane, as well as measurements in retroreflection conditions. This fully automated system is able to measure autonomously a sample's complete spectral BRDF (comprising around 1000 different angular configurations) in less than 4 h.

  20. Ground-based intercomparisons of SBUV/2 flight instruments the world standard Dobson spectrophotometer 83 and overpass observations from Nimbus-7 TOMS and NOAA-11 SBUV/2

    NASA Technical Reports Server (NTRS)

    Heath, D. F.; Ahmad, Z.; Torres, O.; Evans, R. D.; Grass, R. D.; Komhyr, W. A.; Nelson, W.

    1994-01-01

    Total ozone data obtained during summers at Mauna Loa Observatory, Hawaii, with Dobson Spectrophotometer 83 are routinely compared with overpass total ozone data from the Total Ozone Mapping Spectrometer (TOMS) and the Solar Backscatter Ultraviolet (SBUV) spectrometer launched aboard the Nimbus 7 satellite in 1978. Results from the TOMS/Dobson instrument comparisons through 1990 have been presented by McPeters and Komhyr (1991). Dobson spectrophotometer 83 was established as the standard instrument for the U.S.A. Dobson instrument station network in 1962. In 1980, the instrument was designated by the World Meteorological Organization (WMO) as the Standard Dobson Spectrophotometer for the World. Long-term ozone measurement precision of the instrument has been maintained at plus or minus 0.5 percent (Komhyr et al., 1989). On an absolute scale, the ozone measurement accuracy of the instrument is estimated to plus or minus 3 percent. In early April, 1990, comparison of total ozone and vertical distribution (Umkehr) observations were made for the first time with Dobson spectrophotometer 8.3. The work was conducted at the NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) in Boulder, Colorado, and at the research and instrument manufacturing facility of the Ball Aerospace System Division located about 2 km east of Boulder. (The SBUV-2 S/N-2 instrument, built by Ball Aerospace Systems Division, is scheduled for launch aboard the NOAA-13 satellite). We present results of the comparisons which include ozone vertical distribution data obtained with a balloon-borne electrochemical concentration cell (ECC) ozonesonde (Komhyr, 1969).

  1. Recognition of Prior Vocational Learning in Sweden

    ERIC Educational Resources Information Center

    Andersson, Per; Fejes, Andreas; Ahn, Song-Ee

    2004-01-01

    Initiatives in the recognition of prior learning (RPL) have been taken in Sweden in recent years, mainly focusing on prior vocational learning among immigrants. The government started different projects to find methods for recognising a person's prior learning in the field of vocational competence. This article presents a study of how these…

  2. Prior Learning Assessment Workgroup: 2014 Progress Report

    ERIC Educational Resources Information Center

    West, Jim

    2015-01-01

    Legislation passed in 2011 required the Washington Student Achievement Council (WSAC) to convene a Prior Learning Assessment Workgroup. The workgroup was tasked with coordinating and implementing seven goals, described in statute, to promote the award of college credit for prior learning. Awarding college credit for prior learning increases access…

  3. Assessing Prior Learning--A CAEL Handbook.

    ERIC Educational Resources Information Center

    Knapp, Joan

    A model for assessing and awarding credit for prior experiential learning is presented; the adult student's experiences are summarized in a portfolio. The model incorporates eight stages: facilitating the construction and assessment of a portfolio, identifying significant prior experiences, expressing the learning outcomes of prior experiences,…

  4. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A prior sanction shall exist only for... food additive or GRAS regulation promulgated after a general evaluation of use of an ingredient... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  5. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  6. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Prior sanctions. 181.5 Section 181.5 Food and...

  7. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  8. 21 CFR 181.5 - Prior sanctions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... CONSUMPTION (CONTINUED) PRIOR-SANCTIONED FOOD INGREDIENTS General Provisions § 181.5 Prior sanctions. (a) A... use of the ingredient, in order to prevent the adulteration of food in violation of section 402 of the... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Prior sanctions. 181.5 Section 181.5 Food...

  9. Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

    NASA Technical Reports Server (NTRS)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2000-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

  10. Support Vector Machine and Artificial Neural Network Models for the Classification of Grapevine Varieties Using a Portable NIR Spectrophotometer

    PubMed Central

    Gutiérrez, Salvador; Tardaguila, Javier; Fernández-Novales, Juan; Diago, María P.

    2015-01-01

    The identification of different grapevine varieties, currently attended using visual ampelometry, DNA analysis and very recently, by hyperspectral analysis under laboratory conditions, is an issue of great importance in the wine industry. This work presents support vector machine and artificial neural network’s modelling for grapevine varietal classification from in-field leaf spectroscopy. Modelling was attempted at two scales: site-specific and a global scale. Spectral measurements were obtained on the near-infrared (NIR) spectral range between 1600 to 2400 nm under field conditions in a non-destructive way using a portable spectrophotometer. For the site specific approach, spectra were collected from the adaxial side of 400 individual leaves of 20 grapevine (Vitis vinifera L.) varieties one week after veraison. For the global model, two additional sets of spectra were collected one week before harvest from two different vineyards in another vintage, each one consisting on 48 measurement from individual leaves of six varieties. Several combinations of spectra scatter correction and smoothing filtering were studied. For the training of the models, support vector machines and artificial neural networks were employed using the pre-processed spectra as input and the varieties as the classes of the models. The results from the pre-processing study showed that there was no influence whether using scatter correction or not. Also, a second-degree derivative with a window size of 5 Savitzky-Golay filtering yielded the highest outcomes. For the site-specific model, with 20 classes, the best results from the classifiers thrown an overall score of 87.25% of correctly classified samples. These results were compared under the same conditions with a model trained using partial least squares discriminant analysis, which showed a worse performance in every case. For the global model, a 6-class dataset involving samples from three different vineyards, two years and leaves

  11. Support Vector Machine and Artificial Neural Network Models for the Classification of Grapevine Varieties Using a Portable NIR Spectrophotometer.

    PubMed

    Gutiérrez, Salvador; Tardaguila, Javier; Fernández-Novales, Juan; Diago, María P

    2015-01-01

    The identification of different grapevine varieties, currently attended using visual ampelometry, DNA analysis and very recently, by hyperspectral analysis under laboratory conditions, is an issue of great importance in the wine industry. This work presents support vector machine and artificial neural network's modelling for grapevine varietal classification from in-field leaf spectroscopy. Modelling was attempted at two scales: site-specific and a global scale. Spectral measurements were obtained on the near-infrared (NIR) spectral range between 1600 to 2400 nm under field conditions in a non-destructive way using a portable spectrophotometer. For the site specific approach, spectra were collected from the adaxial side of 400 individual leaves of 20 grapevine (Vitis vinifera L.) varieties one week after veraison. For the global model, two additional sets of spectra were collected one week before harvest from two different vineyards in another vintage, each one consisting on 48 measurement from individual leaves of six varieties. Several combinations of spectra scatter correction and smoothing filtering were studied. For the training of the models, support vector machines and artificial neural networks were employed using the pre-processed spectra as input and the varieties as the classes of the models. The results from the pre-processing study showed that there was no influence whether using scatter correction or not. Also, a second-degree derivative with a window size of 5 Savitzky-Golay filtering yielded the highest outcomes. For the site-specific model, with 20 classes, the best results from the classifiers thrown an overall score of 87.25% of correctly classified samples. These results were compared under the same conditions with a model trained using partial least squares discriminant analysis, which showed a worse performance in every case. For the global model, a 6-class dataset involving samples from three different vineyards, two years and leaves

  12. Light absorption cell combining variable path and length pump

    DOEpatents

    Prather, W.S.

    1993-12-07

    A device is described for use in making spectrophotometric measurements of fluid samples. In particular, the device is a measurement cell containing a movable and a fixed lens with a sample of the fluid there between and through which light shines. The cell is connected to a source of light and a spectrophotometer via optic fibers. Movement of the lens varies the path length and also pumps the fluid into and out of the cell. Unidirectional inlet and exit valves cooperate with the movable lens to assure a one-way flow of fluid through the cell. A linear stepper motor controls the movement of the lens and cycles it from a first position closer to the fixed lens and a second position farther from the fixed lens, preferably at least 10 times per minute for a nearly continuous stream of absorption spectrum data. 2 figures.

  13. Light absorption cell combining variable path and length pump

    DOEpatents

    Prather, William S.

    1993-01-01

    A device for use in making spectrophotometric measurements of fluid samples. In particular, the device is a measurement cell containing a movable and a fixed lens with a sample of the fluid therebetween and through which light shines. The cell is connected to a source of light and a spectrophotometer via optic fibers. Movement of the lens varies the path length and also pumps the fluid into and out of the cell. Unidirectional inlet and exit valves cooperate with the movable lens to assure a one-way flow of fluid through the cell. A linear stepper motor controls the movement of the lens and cycles it from a first position closer to the fixed lens and a second position farther from the fixed lens, preferably at least 10 times per minute for a nearly continuous stream of absorption spectrum data.

  14. Determination of mercury in rocks, sediments, and soils by flameless atomic absorption

    SciTech Connect

    White, L.E.; Carter, M.H. Jr.

    1980-05-22

    A simple, relatively fast method for the determination of mercury in rocks, sediments, and soils has been developed to meet the needs of the National Uranium Resources Evaluation Project. One gram of the less than 100 mesh material is placed in a 250-mL reagent bottle and is digested using a mixture of concentrated sulfuric acid and 30% hydrogen peroxide. To prevent the loss of mercury during the digestion procedure, an 18-inch dry reflux tower is employed. After digestion, the sample is treated with 5% potassium permanganate solution, and a sodium chloride-hydroxylamine sulfate reagent. Tin (11) sulfate is then added and the sample immediately attached to an aeration device. The volatilized mercury is swept into an absorption cell by an argon stream and is measured by an atomic absorption spectrophotometer adjusted to 253.7 nanometer wave-length. Absorption is then plotted by a strip chart recorder.

  15. Continuous hyperspectral absorption measurements of colored dissolved organic material in aquatic systems

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Gary J.; Orrico, Cristina; Moline, Mark A.; Oliver, Matthew; Schofield, Oscar M.

    2003-11-01

    The majority of organic carbon in the oceans is present as dissolved organic matter (DOM) therefore understanding the distribution and dynamics of DOM is central to understanding global carbon cycles. Describing the time-space variability in colored dissolved organic matter (CDOM) has been difficult, as standard spectrophotometric methods for CDOM determination are laborious and susceptible to methodological biases. Previously, measurements of CDOM absorption in discrete water samples by use of a liquid-waveguide capillary cell (LWCC) compared favorably with measurements made with a benchtop spectrophotometer. Given this, we focused on automating the LWCC technique to improve our spatial and temporal sampling capabilities for CDOM. We found strong correlations between CDOM absorption spectra collected from discrete water samples using standard methods and selected corresponding CDOM spectra collected by the automated LWCC system. The near-continuous measurements by the LWCC system made it possible to map the temporal, spatial, and spectral variability of CDOM absorption along the ship track.

  16. Variability of light absorption by aquatic particles in the near-infrared spectral region

    NASA Astrophysics Data System (ADS)

    Tassan, Stelvio; Ferrari, Giovanni M.

    2003-08-01

    We have measured the light absorption of a set of particle suspensions of varying nature (pure minerals, particulate standards, aquatic particles) using a double-beam spectrophotometer with a 15-cm-diameter integrating sphere. The sample was located inside the sphere so as to minimize the effect of light scattering by the particles. The results obtained showed highly variable absorption in the near-IR region of the wavelength spectrum. The same particle samples were deposited on glass-fiber filters, and their absorption was measured by the transmittance-reflectance method, based on a theoretical model that corrects for the effect of light scattering. The good agreement found between the results of the measurements carried out inside the sphere and by the transmittance-reflectance method confirms the validity of the scattering correction included in the above method.

  17. The power prior: theory and applications.

    PubMed

    Ibrahim, Joseph G; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

    2015-12-10

    The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A-to-Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Frequentist properties of power priors in posterior inference are established, and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials.

  18. The power prior: theory and applications.

    PubMed

    Ibrahim, Joseph G; Chen, Ming-Hui; Gwon, Yeongjin; Chen, Fang

    2015-12-10

    The power prior has been widely used in many applications covering a large number of disciplines. The power prior is intended to be an informative prior constructed from historical data. It has been used in clinical trials, genetics, health care, psychology, environmental health, engineering, economics, and business. It has also been applied for a wide variety of models and settings, both in the experimental design and analysis contexts. In this review article, we give an A-to-Z exposition of the power prior and its applications to date. We review its theoretical properties, variations in its formulation, statistical contexts for which it has been used, applications, and its advantages over other informative priors. We review models for which it has been used, including generalized linear models, survival models, and random effects models. Statistical areas where the power prior has been used include model selection, experimental design, hierarchical modeling, and conjugate priors. Frequentist properties of power priors in posterior inference are established, and a simulation study is conducted to further examine the empirical performance of the posterior estimates with power priors. Real data analyses are given illustrating the power prior as well as the use of the power prior in the Bayesian design of clinical trials. PMID:26346180

  19. Spectral Absorption By Particulate Impurities in Snow Determined By Photometric Analysis Of Filters

    NASA Astrophysics Data System (ADS)

    Grenfell, T. C.; Doherty, S. J.; Clarke, A. D.

    2009-12-01

    Our work is motivated by the 1983-84 survey by Clarke and Noone (Atmos. Environ., 1985) of soot in Arctic snow. Our objective is to resurvey the original area they covered and to extend the observations around the entire Arctic Basin under the auspices of the IPY program. We use the filtering and integrating sandwich techniques developed by Clarke and Noone to process the snow samples. Among the advantages of this method are that (a) it provides a direct measure of light absorption and the result is closely related to the actual absorption of sunlight in the snow or ice, (b) processing and filtering of the snow samples can be carried out in remote locations and (c) it is not necessary to transport large quantities of snow back to our home laboratory. Here we describe the construction, calibration, and some applications of an integrating sphere spectrophotometer system designed to take advantage of recent advances in instrumentation to improve the accuracy of measurements of absorption by particulate impurities collected on nuclepore filters used in our survey. Filter loading in terms of effective black carbon (BC) amount is determined together with the ratio of non-BC to BC concentrations using a set of reference filters with known loadings of Monarch 71 BC prepared by A. D. Clarke. The new spectrophotometer system has (a) system stability of approximately 0.5%; (b) precision relative to ADC standards of 3-4% for filter loadings greater than about 0.5 microgm Carbon/cm2. (c) We can distinguish BC from non-BC from relative spectral shapes of the energy absorption curves with an accuracy that depends on our knowledge of the spectral absorption curves of the non-BC components; and (d) by-eye estimates are consistent with spectrophotometric results. The major outstanding uncertainty is the appropriate value to use for the mass absorption efficiency for BC.

  20. Frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissuelike phantom

    NASA Astrophysics Data System (ADS)

    Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela

    1995-03-01

    We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute

  1. Calibration Transfer Between a Bench Scanning and a Submersible Diode Array Spectrophotometer for In Situ Wastewater Quality Monitoring in Sewer Systems.

    PubMed

    Brito, Rita S; Pinheiro, Helena M; Ferreira, Filipa; Matos, José S; Pinheiro, Alexandre; Lourenço, Nídia D

    2016-03-01

    Online monitoring programs based on spectroscopy have a high application potential for the detection of hazardous wastewater discharges in sewer systems. Wastewater hydraulics poses a challenge for in situ spectroscopy, especially when the system includes storm water connections leading to rapid changes in water depth, velocity, and in the water quality matrix. Thus, there is a need to optimize and fix the location of in situ instruments, limiting their availability for calibration. In this context, the development of calibration models on bench spectrophotometers to estimate wastewater quality parameters from spectra acquired with in situ instruments could be very useful. However, spectra contain information not only from the samples, but also from the spectrophotometer generally invalidating this approach. The use of calibration transfer methods is a promising solution to this problem. In this study, calibration models were developed using interval partial least squares (iPLS), for the estimation of total suspended solids (TSS) and chemical oxygen demand (COD) in sewage from Ultraviolet-visible spectra acquired in a bench scanning spectrophotometer. The feasibility of calibration transfer to a submersible, diode array equipment, to be subsequently operated in situ, was assessed using three procedures: slope and bias correction (SBC); single wavelength standardization (SWS) on mean spectra; and local centering (LC). The results showed that SBC was the most adequate for the available data, adding insignificant error to the base model estimates. Single wavelength standardization was a close second best, potentially more robust, and independent of the base iPLS model. Local centering was shown to be inadequate for the samples and instruments used.

  2. Calibration Transfer Between a Bench Scanning and a Submersible Diode Array Spectrophotometer for In Situ Wastewater Quality Monitoring in Sewer Systems.

    PubMed

    Brito, Rita S; Pinheiro, Helena M; Ferreira, Filipa; Matos, José S; Pinheiro, Alexandre; Lourenço, Nídia D

    2016-03-01

    Online monitoring programs based on spectroscopy have a high application potential for the detection of hazardous wastewater discharges in sewer systems. Wastewater hydraulics poses a challenge for in situ spectroscopy, especially when the system includes storm water connections leading to rapid changes in water depth, velocity, and in the water quality matrix. Thus, there is a need to optimize and fix the location of in situ instruments, limiting their availability for calibration. In this context, the development of calibration models on bench spectrophotometers to estimate wastewater quality parameters from spectra acquired with in situ instruments could be very useful. However, spectra contain information not only from the samples, but also from the spectrophotometer generally invalidating this approach. The use of calibration transfer methods is a promising solution to this problem. In this study, calibration models were developed using interval partial least squares (iPLS), for the estimation of total suspended solids (TSS) and chemical oxygen demand (COD) in sewage from Ultraviolet-visible spectra acquired in a bench scanning spectrophotometer. The feasibility of calibration transfer to a submersible, diode array equipment, to be subsequently operated in situ, was assessed using three procedures: slope and bias correction (SBC); single wavelength standardization (SWS) on mean spectra; and local centering (LC). The results showed that SBC was the most adequate for the available data, adding insignificant error to the base model estimates. Single wavelength standardization was a close second best, potentially more robust, and independent of the base iPLS model. Local centering was shown to be inadequate for the samples and instruments used. PMID:26798079

  3. Improving Open Access through Prior Learning Assessment

    ERIC Educational Resources Information Center

    Yin, Shuangxu; Kawachi, Paul

    2013-01-01

    This paper explores and presents new data on how to improve open access in distance education through using prior learning assessments. Broadly there are three types of prior learning assessment (PLAR): Type-1 for prospective students to be allowed to register for a course; Type-2 for current students to avoid duplicating work-load to gain…

  4. Prior Computer Experience and Technology Acceptance

    ERIC Educational Resources Information Center

    Varma, Sonali

    2010-01-01

    Prior computer experience with information technology has been identified as a key variable (Lee, Kozar, & Larsen, 2003) that can influence an individual's future use of newer computer technology. The lack of a theory driven approach to measuring prior experience has however led to conceptually different factors being used interchangeably in…

  5. 28 CFR 2.58 - Prior orders.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Prior orders. 2.58 Section 2.58 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS, YOUTH OFFENDERS, AND JUVENILE DELINQUENTS United States Code Prisoners and Parolees § 2.58 Prior orders. Any order...

  6. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  7. Spectrophotometer properties of vein blood plasma in UF-region patients with sharp surgical pathology of abdominal region organs

    NASA Astrophysics Data System (ADS)

    Guminestskij, S. G.; Polianski, I. J.; Motrich, A. V.; Grunchuk, F. W.

    2006-05-01

    It is set that there are two maximums in UF- region absorption of vein blood plasma of a man: at λ = 235 nm and at λ = 280 nm. It is shown that there are the substantial changes of values of the optical density D comparative with controls (for donors) exactly in a maximum at development of sharp surgical diseases of organs of abdominal region λ = 280 nm, in that time as maximum at λ = 235 nm in this plan is not informing. Resulted results of researches of dynamics of changes of optical properties of vein blood plasma in UF- region of patients with pathology of abdominal region organs in after operating period (sharp appendicitis, sharp pancreatitis, intestinal impassability and others like that), which can have the diagnostic value.

  8. Surfactant-Assisted Nanodrop Spectrophotometer Determination of Iron(III) in a Single Drop of Food, Biological, and Environmental Samples

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Tapadia, K.; Sahin, R.; Shrivas, K.

    2016-01-01

    A surfactant-assisted nanodrop spectrophotometric (NDS) method has been developed for the determination of the iron(III) content in single drops (1 μ L) of food, biological, and or environmental sample using disodium 1-nitroso-2-naphthol-3,6-sulfonate (Nitroso-R salt) as a complexing agent and Tween-80 as non-ionic surfactant at pH 4.0. This method is based on the formation of a complex between the Fe(III) present in a sample and the Nitroso-R-salt in the presence of a surfactant to form a green-colored Fe(III)-Nitroso-R salt complex, which can be measured using a NDS method at a λ max = 710 nm. This system was found to obey Beer's law at concentrations in the range of 50-5000 μ g/L with slope, intercept and correlation coefficient values of 0.683, 0.102, and 0.986, respectively. The molar absorptivity of the complex in terms of the Fe(III) content was determined to be 4.86 × 10 5 L· mol -1 · cm -1 . The detection limit and %RSD values of the method were found to be 17 × 10-3 mg/L and ±1.3706%, respectively. This newly developed method was successfully applied to the determination of the Fe(III) content in single drops of food, biological, and environmental samples, and the results were compared with those obtained by atomic absorption spectrometry.

  9. Informative prior distributions for ELISA analyses.

    PubMed

    Klauenberg, Katy; Walzel, Monika; Ebert, Bernd; Elster, Clemens

    2015-07-01

    Immunoassays are capable of measuring very small concentrations of substances in solutions and have an immense range of application. Enzyme-linked immunosorbent assay (ELISA) tests in particular can detect the presence of an infection, of drugs, or hormones (as in the home pregnancy test). Inference of an unknown concentration via ELISA usually involves a non-linear heteroscedastic regression and subsequent prediction, which can be carried out in a Bayesian framework. For such a Bayesian inference, we are developing informative prior distributions based on extensive historical ELISA tests as well as theoretical considerations. One consideration regards the quality of the immunoassay leading to two practical requirements for the applicability of the priors. Simulations show that the additional prior information can lead to inferences which are robust to reasonable perturbations of the model and changes in the design of the data. On real data, the applicability is demonstrated across different laboratories, for different analytes and laboratory equipment as well as for previous and current ELISAs with sigmoid regression function. Consistency checks on real data (similar to cross-validation) underpin the adequacy of the suggested priors. Altogether, the new priors may improve concentration estimation for ELISAs that fulfill certain design conditions, by extending the range of the analyses, decreasing the uncertainty, or giving more robust estimates. Future use of these priors is straightforward because explicit, closed-form expressions are provided. This work encourages development and application of informative, yet general, prior distributions for other types of immunoassays.

  10. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  11. A Simulation of Pell Grant Awards and Costs Using Prior-Prior Year Financial Data

    ERIC Educational Resources Information Center

    Kelchen, Robert; Jones, Gigi

    2015-01-01

    We examine the likely implications of switching from a prior year (PY) financial aid system, the current practice in which students file the Free Application for Federal Student Aid (FAFSA) using income data from the previous tax year, to prior-prior year (PPY), in which data from two years before enrollment is used. While PPY allows students to…

  12. X-ray absorption spectroscopy of metalloproteins.

    PubMed

    Ward, Jesse; Ollmann, Emily; Maxey, Evan; Finney, Lydia A

    2014-01-01

    Metalloproteins are enormously important in biology. While a variety of techniques exist for studying metals in biology, X-ray absorption spectroscopy is particularly useful in that it can determine the local electronic and physical structure around the metal center, and is one of the few avenues for studying "spectroscopically silent" metal ions like Zn(II) and Cu(I) that have completely filled valence bands. While X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) are useful for studying metalloprotein structure, they suffer the limitation that the detected signal is an average of all the various metal centers in the sample, which limits its usefulness for studying metal centers in situ or in cell lysates. It would be desirable to be able to separate the various proteins in a mixture prior to performing X-ray absorption studies, so that the derived signal is from one species only. Here we describe a method for performing X-ray absorption spectroscopy on protein bands following electrophoretic separation and western blotting.

  13. Effect of Sn on the optical band gap determined using absorption spectrum fitting method

    SciTech Connect

    Heera, Pawan; Kumar, Anup; Sharma, Raman

    2015-05-15

    We report the preparation and the optical studies on tellurium rich glasses thin films. The thin films of Se{sub 30}Te{sub 70-x} Sn{sub x} system for x= 0, 1.5, 2.5 and 4.5 glassy alloys prepared by melt quenching technique are deposited on the glass substrate using vacuum thermal evaporation technique. The analysis of absorption spectra in the spectral range 400nm–4000 nm at room temperature obtained from UV-VIS-NIR spectrophotometer [Perkin Elmer Lamda-750] helps us in the optical characterization of the thin films under study. The absorption spectrum fitting method is applied by using the Tauc’s model for estimating the optical band gap and the width of the band tail of the thin films. The optical band gap is calculated and is found to decrease with the Sn content.

  14. On the prior distribution of extinction time.

    PubMed

    Solow, Andrew R

    2016-06-01

    Bayesian inference about the extinction of a species based on a record of its sightings requires the specification of a prior distribution for extinction time. Here, I critically review some specifications in the context of a specific model of the sighting record. The practical implication of the choice of prior distribution is illustrated through an application to the sighting record of the Caribbean monk seal. PMID:27277952

  15. Varying prior information in Bayesian inversion

    NASA Astrophysics Data System (ADS)

    Walker, Matthew; Curtis, Andrew

    2014-06-01

    Bayes' rule is used to combine likelihood and prior probability distributions. The former represents knowledge derived from new data, the latter represents pre-existing knowledge; the Bayesian combination is the so-called posterior distribution, representing the resultant new state of knowledge. While varying the likelihood due to differing data observations is common, there are also situations where the prior distribution must be changed or replaced repeatedly. For example, in mixture density neural network (MDN) inversion, using current methods the neural network employed for inversion needs to be retrained every time prior information changes. We develop a method of prior replacement to vary the prior without re-training the network. Thus the efficiency of MDN inversions can be increased, typically by orders of magnitude when applied to geophysical problems. We demonstrate this for the inversion of seismic attributes in a synthetic subsurface geological reservoir model. We also present results which suggest that prior replacement can be used to control the statistical properties (such as variance) of the final estimate of the posterior in more general (e.g., Monte Carlo based) inverse problem solutions.

  16. An approach to prior austenite reconstruction

    SciTech Connect

    Abbasi, Majid; Nelson, Tracy W.; Sorensen, Carl D.; Wei Lingyun

    2012-04-15

    One area of interest in Friction Stir Welding (FSW) of steels is to understand microstructural evolution during the process. Most of the deformation occurs in the austenite temperature range. Quantitative microstructural measurements of prior austenite microstructure are needed in order to understand evolution of the microstructure. Considering the fact that room temperature microstructure in ferritic steels contains very little to no retained austenite, prior austenite microstructure needs to be recovered from the room temperature ferrite. In this paper, an approach based on Electron Backscattered Diffraction (EBSD) is introduced to detect Bain zones. Bain zone detection is used to reconstruct prior austenite grain structure. Additionally, a separate approach based on phase transformation orientation relationships is introduced in order to recover prior austenite orientation. - Highlights: Black-Right-Pointing-Pointer This approach provides a tool to reconstruct large-scale austenite microstructures. Black-Right-Pointing-Pointer It recovers prior austenite orientation without relying on retained austenite. Black-Right-Pointing-Pointer It utilizes EBSD data from the room temperature microstructure. Black-Right-Pointing-Pointer Higher number of active variants leads to more accurate reconstructions. Black-Right-Pointing-Pointer At least two variants are needed in order to recover prior austenite orientation.

  17. Attentional and Contextual Priors in Sound Perception

    PubMed Central

    Wolmetz, Michael; Elhilali, Mounya

    2016-01-01

    Behavioral and neural studies of selective attention have consistently demonstrated that explicit attentional cues to particular perceptual features profoundly alter perception and performance. The statistics of the sensory environment can also provide cues about what perceptual features to expect, but the extent to which these more implicit contextual cues impact perception and performance, as well as their relationship to explicit attentional cues, is not well understood. In this study, the explicit cues, or attentional prior probabilities, and the implicit cues, or contextual prior probabilities, associated with different acoustic frequencies in a detection task were simultaneously manipulated. Both attentional and contextual priors had similarly large but independent impacts on sound detectability, with evidence that listeners tracked and used contextual priors for a variety of sound classes (pure tones, harmonic complexes, and vowels). Further analyses showed that listeners updated their contextual priors rapidly and optimally, given the changing acoustic frequency statistics inherent in the paradigm. A Bayesian Observer model accounted for both attentional and contextual adaptations found with listeners. These results bolster the interpretation of perception as Bayesian inference, and suggest that some effects attributed to selective attention may be a special case of contextual prior integration along a feature axis. PMID:26882228

  18. Attentional and Contextual Priors in Sound Perception.

    PubMed

    Wolmetz, Michael; Elhilali, Mounya

    2016-01-01

    Behavioral and neural studies of selective attention have consistently demonstrated that explicit attentional cues to particular perceptual features profoundly alter perception and performance. The statistics of the sensory environment can also provide cues about what perceptual features to expect, but the extent to which these more implicit contextual cues impact perception and performance, as well as their relationship to explicit attentional cues, is not well understood. In this study, the explicit cues, or attentional prior probabilities, and the implicit cues, or contextual prior probabilities, associated with different acoustic frequencies in a detection task were simultaneously manipulated. Both attentional and contextual priors had similarly large but independent impacts on sound detectability, with evidence that listeners tracked and used contextual priors for a variety of sound classes (pure tones, harmonic complexes, and vowels). Further analyses showed that listeners updated their contextual priors rapidly and optimally, given the changing acoustic frequency statistics inherent in the paradigm. A Bayesian Observer model accounted for both attentional and contextual adaptations found with listeners. These results bolster the interpretation of perception as Bayesian inference, and suggest that some effects attributed to selective attention may be a special case of contextual prior integration along a feature axis.

  19. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  20. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  1. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  2. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  3. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  4. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  5. Global Surface Photosynthetic Biosignatures Prior to the Rise of Oxygen

    NASA Astrophysics Data System (ADS)

    Parenteau, M. N.; Kiang, N. Y.; Blankenship, R. E.; Sanromá, E.; Palle Bago, E.; Hoehler, T. M.; Pierson, B. K.; Meadows, V. S.

    2015-12-01

    The study of potential exoplanet biosignatures -- the global impact of life on a planetary environment -- has been informed primarily by the modern Earth, with little yet explored beyond atmospheric O2 from oxygenic photosynthesis out of chemical equilibrium, and its accompanying planetary surface reflectance feature, the vegetation "red edge" reflectance. However, these biosignatures have only been present for less than half the Earth's history, and recent geochemical evidence suggests that atmospheric O2 may have been at very low - likely undetectable - levels, until 0.8 Ga (Planavsky et al., 2014, Science 346:635-638). Given that our planet was inhabited for very long periods prior to the rise of oxygen, and that a similar period of anoxygenic life may occur on exoplanets, more studies are needed to characterize remotely detectable biosignatures associated with more evolutionarily ancient anoxygenic phototrophs. Our measurements of the surface reflectance spectra of pure cultures of anoxygenic phototrophs revealed "NIR edge(s)" due to absorption of light by bacteriochlorophyll (Bchl) pigments. We used the pure culture spectra to deconvolve complex spectra of environmental samples of microbial mats. We observed multiple NIR edges associated with multiple pigments in the mats. We initially expected only to detect the absorption of light by the pigments in the surface layer of the mat. Surprisingly, we detected cyanobacterial Chl a in the surface layer, as well as Bchl c and Bchl a in the anoxygenic underlayers. This suggests that it does not matter "who's on top," as we were able to observe pigments through all mat layers due to their different absorption maxima. The presence of multiple pigments and thus multiple "NIR edges" could signify layered phototrophic communities and possibly strengthen support for the detection of a surface exoplanet biosignature. In general, the proposed work will inform the search for life on exoplanets at a similar stage of evolution

  6. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  7. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  8. Commissioning of the PRIOR proton microscope

    DOE PAGES

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; et al

    2016-02-18

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5–4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This study describes the PRIOR setup as well asmore » the results of the first static and dynamic protonradiography experiments performed at GSI.« less

  9. Commissioning of the PRIOR proton microscope.

    PubMed

    Varentsov, D; Antonov, O; Bakhmutova, A; Barnes, C W; Bogdanov, A; Danly, C R; Efimov, S; Endres, M; Fertman, A; Golubev, A A; Hoffmann, D H H; Ionita, B; Kantsyrev, A; Krasik, Ya E; Lang, P M; Lomonosov, I; Mariam, F G; Markov, N; Merrill, F E; Mintsev, V B; Nikolaev, D; Panyushkin, V; Rodionova, M; Schanz, M; Schoenberg, K; Semennikov, A; Shestov, L; Skachkov, V S; Turtikov, V; Udrea, S; Vasylyev, O; Weyrich, K; Wilde, C; Zubareva, A

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI. PMID:26931841

  10. Commissioning of the PRIOR proton microscope

    NASA Astrophysics Data System (ADS)

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; Hoffmann, D. H. H.; Ionita, B.; Kantsyrev, A.; Krasik, Ya. E.; Lang, P. M.; Lomonosov, I.; Mariam, F. G.; Markov, N.; Merrill, F. E.; Mintsev, V. B.; Nikolaev, D.; Panyushkin, V.; Rodionova, M.; Schanz, M.; Schoenberg, K.; Semennikov, A.; Shestov, L.; Skachkov, V. S.; Turtikov, V.; Udrea, S.; Vasylyev, O.; Weyrich, K.; Wilde, C.; Zubareva, A.

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI.

  11. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  12. Student Models for Prior Knowledge Estimation

    ERIC Educational Resources Information Center

    Nižnan, Juraj; Pelánek, Radek; Rihák, Jirí

    2015-01-01

    Intelligent behavior of adaptive educational systems is based on student models. Most research in student modeling focuses on student learning (acquisition of skills). We focus on prior knowledge, which gets much less attention in modeling and yet can be highly varied and have important consequences for the use of educational systems. We describe…

  13. Recognition of Prior Learning: The Participants' Perspective

    ERIC Educational Resources Information Center

    Miguel, Marta C.; Ornelas, José H.; Maroco, João P.

    2016-01-01

    The current narrative on lifelong learning goes beyond formal education and training, including learning at work, in the family and in the community. Recognition of prior learning is a process of evaluation of those skills and knowledge acquired through life experience, allowing them to be formally recognized by the qualification systems. It is a…

  14. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  15. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  16. 7 CFR 2500.049 - Prior approvals.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Prior approvals. 2500.049 Section 2500.049 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF ADVOCACY AND OUTREACH, DEPARTMENT OF AGRICULTURE OAO FEDERAL FINANCIAL ASSISTANCE PROGRAMS-GENERAL AWARD ADMINISTRATIVE...

  17. Understanding the Complexities of Prior Knowledge

    ERIC Educational Resources Information Center

    Soiferman, L. Karen

    2014-01-01

    The purpose of the study was to gain an understanding of the kinds of prior knowledge students bring with them from high school as it relates to the conventions of writing that they are expected to follow in ARTS 1110 Introduction to University. The research questions were "Can first-year students taking the Arts 1110 Introduction to…

  18. 22 CFR 129.8 - Prior notification.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Prior notification. 129.8 Section 129.8 Foreign Relations DEPARTMENT OF STATE INTERNATIONAL TRAFFIC IN ARMS REGULATIONS REGISTRATION AND LICENSING OF.... (c) The procedures outlined in § 126.8(c) through (g) are equally applicable with respect to...

  19. Prior Learning Assessment: Outcomes and Characteristics.

    ERIC Educational Resources Information Center

    White, Barbara

    1995-01-01

    Describes the Ontario college system's Prior Learning Assessment program for adult learners, focusing on outcomes and characteristics of students completing the process at Seneca College from April 1994 to February 1995. Indicates that of 77 participants, 46 were female, the mean age was 31, and 81% passed the process successfully. (BCY)

  20. Tuning Your Priors to the World

    PubMed Central

    Feldman, Jacob

    2013-01-01

    The idea that perceptual and cognitive systems must incorporate knowledge about the structure of the environment has become a central dogma of cognitive theory. In a Bayesian context, this idea is often realized in terms of “tuning the prior”—widely assumed to mean adjusting prior probabilities so that they match the frequencies of events in the world. This kind of “ecological” tuning has often been held up as an ideal of inference, in fact defining an “ideal observer.” But widespread as this viewpoint is, it directly contradicts Bayesian philosophy of probability, which views probabilities as degrees of belief rather than relative frequencies, and explicitly denies that they are objective characteristics of the world. Moreover, tuning the prior to observed environmental frequencies is subject to overfitting, meaning in this context overtuning to the environment, which leads (ironically) to poor performance in future encounters with the same environment. Whenever there is uncertainty about the environment—which there almost always is—an agent's prior should be biased away from ecological relative frequencies and toward simpler and more entropic priors. PMID:23335572

  1. Objective prior distribution of climate sensitivity

    NASA Astrophysics Data System (ADS)

    Pueyo, S.

    2012-04-01

    The problems posed by the choice of prior distribution constitute one of the most fundamental obstacles to assign probabilities to the possible values of climate sensitivity S. The prior is the probability distribution that we assume before introducing data. In the literature about climate sensitivity, the most frequently used prior is the uniform. On first inspection, this distribution would seem to represent absence of information, but, as is well known, this assumption leads to paradoxes. This observation has led to the widespread belief that priors are inherently subjective and should be decided by expert elicitation, even though this amounts to questioning the objective value of scientific results. In general, the climate science community is unaware of the "objective Bayesian" literature, which seeks objective criteria to determine non-informative prior distributions (or reference priors). In a recent paper (Pueyo 2011) I applied an objective Bayesian approach to climate sensitivity. I described three lines of evidence indicating that the distribution that really represents absence of information about S is log-uniform, i.e. it consists of a uniform distribution of log(S) instead of S: • In the case of S, only the log-uniform distribution satisfies Jaynes' invariant groups criterion, i.e. this distribution does not change when modifying assumptions that are not explicitly included in the enunciate of the problem (I only included the definition of S). • In terms of information theory, information about S can be identified with mutual information between changes in radiative forcing and in temperature. Absence of mutual information between these variables implies a log-uniform distribution of S. • The frequency distribution of sets of parameters formally comparable to climate sensitivity is approximately log-uniform for a broad range of values. A log-uniform distribution of S is intermediate between a uniform distribution of S and a uniform distribution

  2. Prior voluntary wheel running attenuates neuropathic pain.

    PubMed

    Grace, Peter M; Fabisiak, Timothy J; Green-Fulgham, Suzanne M; Anderson, Nathan D; Strand, Keith A; Kwilasz, Andrew J; Galer, Erika L; Walker, Frederick Rohan; Greenwood, Benjamin N; Maier, Steven F; Fleshner, Monika; Watkins, Linda R

    2016-09-01

    Exercise is known to exert a systemic anti-inflammatory influence, but whether its effects are sufficient to protect against subsequent neuropathic pain is underinvestigated. We report that 6 weeks of voluntary wheel running terminating before chronic constriction injury (CCI) prevented the full development of allodynia for the ∼3-month duration of the injury. Neuroimmune signaling was assessed at 3 and 14 days after CCI. Prior exercise normalized ipsilateral dorsal spinal cord expression of neuroexcitatory interleukin (IL)-1β production and the attendant glutamate transporter GLT-1 decrease, as well as expression of the disinhibitory P2X4R-BDNF axis. The expression of the macrophage marker Iba1 and the chemokine CCL2 (MCP-1), and a neuronal injury marker (activating transcription factor 3), was attenuated by prior running in the ipsilateral lumbar dorsal root ganglia. Prior exercise suppressed macrophage infiltration and/or injury site proliferation, given decreased presence of macrophage markers Iba1, iNOS (M1), and Arg-1 (M2; expression was time dependent). Chronic constriction injury-driven increases in serum proinflammatory chemokines were suppressed by prior running, whereas IL-10 was increased. Peripheral blood mononuclear cells were also stimulated with lipopolysaccharide ex vivo, wherein CCI-induced increases in IL-1β, nitrite, and IL-10 were suppressed by prior exercise. Last, unrestricted voluntary wheel running, beginning either the day of, or 2 weeks after, CCI, progressively reversed neuropathic pain. This study is the first to investigate the behavioral and neuroimmune consequences of regular exercise terminating before nerve injury. This study suggests that chronic pain should be considered a component of "the diseasome of physical inactivity," and that an active lifestyle may prevent neuropathic pain. PMID:27355182

  3. Prior voluntary wheel running attenuates neuropathic pain.

    PubMed

    Grace, Peter M; Fabisiak, Timothy J; Green-Fulgham, Suzanne M; Anderson, Nathan D; Strand, Keith A; Kwilasz, Andrew J; Galer, Erika L; Walker, Frederick Rohan; Greenwood, Benjamin N; Maier, Steven F; Fleshner, Monika; Watkins, Linda R

    2016-09-01

    Exercise is known to exert a systemic anti-inflammatory influence, but whether its effects are sufficient to protect against subsequent neuropathic pain is underinvestigated. We report that 6 weeks of voluntary wheel running terminating before chronic constriction injury (CCI) prevented the full development of allodynia for the ∼3-month duration of the injury. Neuroimmune signaling was assessed at 3 and 14 days after CCI. Prior exercise normalized ipsilateral dorsal spinal cord expression of neuroexcitatory interleukin (IL)-1β production and the attendant glutamate transporter GLT-1 decrease, as well as expression of the disinhibitory P2X4R-BDNF axis. The expression of the macrophage marker Iba1 and the chemokine CCL2 (MCP-1), and a neuronal injury marker (activating transcription factor 3), was attenuated by prior running in the ipsilateral lumbar dorsal root ganglia. Prior exercise suppressed macrophage infiltration and/or injury site proliferation, given decreased presence of macrophage markers Iba1, iNOS (M1), and Arg-1 (M2; expression was time dependent). Chronic constriction injury-driven increases in serum proinflammatory chemokines were suppressed by prior running, whereas IL-10 was increased. Peripheral blood mononuclear cells were also stimulated with lipopolysaccharide ex vivo, wherein CCI-induced increases in IL-1β, nitrite, and IL-10 were suppressed by prior exercise. Last, unrestricted voluntary wheel running, beginning either the day of, or 2 weeks after, CCI, progressively reversed neuropathic pain. This study is the first to investigate the behavioral and neuroimmune consequences of regular exercise terminating before nerve injury. This study suggests that chronic pain should be considered a component of "the diseasome of physical inactivity," and that an active lifestyle may prevent neuropathic pain.

  4. Spectral priors improve near-infrared diffuse tomography more than spatial priors

    NASA Astrophysics Data System (ADS)

    Brooksby, Ben; Srinivasan, Subhadra; Jiang, Shudong; Dehghani, Hamid; Pogue, Brian W.; Paulsen, Keith D.; Weaver, John; Kogel, Christine; Poplack, Steven P.

    2005-08-01

    We compare the benefits of spatial and spectral priors in near-infrared diffuse tomography image reconstruction. Although previous studies that incorporated anatomical spatial priors have shown improvement in algorithm convergence and resolution, our results indicate that functional parameter quantification by this approach can be suboptimal. The incorporation of a priori spectral information significantly improves the accuracy observed in recovered images. Specifically, phantom results show that the maximum total hemoglobin concentration ([HbT]) in a region of heterogeneity reached 91% of the true value compared to 63% using spatial priors. The combination of both priors produced results accurate to 98% of the true [HbT]. When both spatial and spectral priors were applied in a healthy volunteer, glandular tissue showed a higher [HbT], water fraction, and scattering power compared to adipose tissue.

  5. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the hydrophobic nature of lipids, dietary fat is handled differently than protein or carbohydrate with respect with digestion and absorption. Dietary fats are broken down throughout the gastrointestinal system. A unique group of enzymes and cofactors allows this process to proceed in an eff...

  6. Absorption driven focus shift

    NASA Astrophysics Data System (ADS)

    Harrop, N.; Wolf, S.; Maerten, O.; Dudek, K.; Ballach, S.; Kramer, R.

    2016-03-01

    Modern high brilliance near infrared lasers have seen a tremendous growth in applications throughout the world. Increased productivity has been achieved by higher laser power and increased brilliance of lasers. Positive impacts on the performance and costs of parts are opposed to threats on process stability and quality, namely shift of focus position over time. A high initial process quality will be reduced by contamination of optics, eventually leading to a focus shift or even destruction of the optics. Focus analysis at full power of multi-kilowatt high brilliance lasers is a very demanding task because of high power densities in the spot and the high power load on optical elements. With the newly developed high power projection optics, the High-Power Micro-Spot Monitor High Brilliance (HP-MSM-HB) is able to measure focus diameter as low as 20 μm at power levels up to 10 kW at very low internal focus shift. A main driving factor behind thermally induced focus shift is the absorption level of the optical element. A newly developed measuring system is designed to determine the relative absorption level in reference to a gold standard. Test results presented show a direct correlation between absorption levels and focus shift. The ability to determine the absorption level of optical elements as well as their performance at full processing power before they are put to use, enables a high level of quality assurance for optics manufacturers and processing head manufacturers alike.

  7. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  8. Cholesterol Absorption and Metabolism.

    PubMed

    Howles, Philip N

    2016-01-01

    Inhibitors of cholesterol absorption have been sought for decades as a means to treat and prevent cardiovascular diseases (CVDs) associated with hypercholesterolemia. Ezetimibe is the one clear success story in this regard, and other compounds with similar efficacy continue to be sought. In the last decade, the laboratory mouse, with all its genetic power, has become the premier experimental model for discovering the mechanisms underlying cholesterol absorption and has become a critical tool for preclinical testing of potential pharmaceutical entities. This chapter briefly reviews the history of cholesterol absorption research and the various gene candidates that have come under consideration as drug targets. The most common and versatile method of measuring cholesterol absorption is described in detail along with important considerations when interpreting results, and an alternative method is also presented. In recent years, reverse cholesterol transport (RCT) has become an area of intense new interest for drug discovery since this process is now considered another key to reducing CVD risk. The ultimate measure of RCT is sterol excretion and a detailed description is given for measuring neutral and acidic fecal sterols and interpreting the results. PMID:27150091

  9. Development of Singlet Oxygen Absorption Capacity (SOAC) Assay Method Using a Microplate Reader.

    PubMed

    Takahashi, Shingo; Iwasaki-Kino, Yuko; Aizawa, Koichi; Terao, Junji; Mukai, Kazuo

    2016-01-01

    Recently, a new assay method that can quantify the singlet oxygen absorption capacity (SOAC) of natural antioxidants and food extracts was developed. The SOAC values were measured in ethanol-chloroform-D2O (50 + 50 + 1, v/v/v) solution at 35°C using a UV-Vis spectrophotometer equipped with a six-channel cell positioner and an electron-temperature control unit. In the present study, measurement of the SOAC values was performed for eight representative carotenoids and three vegetable extracts (tomato, carrot, and red paprika) using a versatile instrument, the microplate reader. A 24-well glass microplate was used for measurements because a plastic microplate, commonly used in the laboratory, dissolves in the ethanol-chloroform-D2O solution. The SOAC values of eight carotenoids and three vegetable extracts measured using a microplate reader were in good agreement with the corresponding values measured using a UV-Vis spectrophotometer, suggesting that the microplate reader is an applicable instrument for the measurement of reliable SOAC values for general antioxidants and food extracts in solution. PMID:26822807

  10. Imaging Grating SpectroPhotometer (I-GRASP) for Solar Soft X-Ray Spectra and Images from a Cube Sat Mission

    NASA Astrophysics Data System (ADS)

    Didkovsky, Leonid V.; Wieman, Seth; Woods, Thomas N.; Jones, Andrew; Chao, Weilun

    2016-05-01

    We describe the Soft X-ray Imaging Grating SpectroPhotometer (I-GRASP), a novel spectrophotometer with four times narrower transmission grating period (about 50 nm) compared to the MIT-designed 200 nm gratings successfully used for the SOHO/SEM, the SDO/EVE/ESP, and the Solar Aspect Monitor (SAM) onboard the EVE sounding rocket suite of instruments. The new grating is based on technology developed at the Lawrence Berkeley National Laboratory (LBNL) and provides four to five time greater diffraction dispersion than the 200 nm period gratings. Such new technology will provide detection of both 0.1 nm - resolved solar spectra in about 1.0 to 7.0 nm spectral range and a soft X-ray pin-hole solar image from the I-GRASP instrument that is appropriately sized for a CubeSat platform. The solar observations of this soft X-ray range do not currently have spectral resolution, so I-GRASP concurrent spectral and imaging X-ray observations will be important for:Improvements in modeling of coronal dynamics and heating by comparing measured and modeled spectra through identifying changes in abundances from different active regions- Resolving some differences in certain iron spectral line intensity ratios observed with SAM, identifying key emission lines, and comparing to those modeled with the CHIANTI atomic database- Studying SXR spectral variability for different solar activity periods including solar flares and the 27-day solar rotation- Studying of the Earth’s ionosphere, thermosphere and mesosphere responses using as input the detailed soft X-ray spectra from I-GRASP- Improving solar soft X-ray reference spectra for accurate calculations of absolute solar irradiance from the SDO/EVE/ESP, SDO/EVE/SAM, TIMED/SEE/XPS, and SORCE/XPS channels that have broadband measurements of the 1-7 nm band- Providing validation for the soft X-Ray observations from the MinXSS CubeSat X123 spectrometer (0.04 to 2.5 nm) with the I-GRASP spectral observations from 1.0 to 7.0 nm- Comparing I

  11. Image Reconstruction Using Analysis Model Prior.

    PubMed

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  12. Knowledge Modeling in Prior Art Search

    NASA Astrophysics Data System (ADS)

    Graf, Erik; Frommholz, Ingo; Lalmas, Mounia; van Rijsbergen, Keith

    This study explores the benefits of integrating knowledge representations in prior art patent retrieval. Key to the introduced approach is the utilization of human judgment available in the form of classifications assigned to patent documents. The paper first outlines in detail how a methodology for the extraction of knowledge from such an hierarchical classification system can be established. Further potential ways of integrating this knowledge with existing Information Retrieval paradigms in a scalable and flexible manner are investigated. Finally based on these integration strategies the effectiveness in terms of recall and precision is evaluated in the context of a prior art search task for European patents. As a result of this evaluation it can be established that in general the proposed knowledge expansion techniques are particularly beneficial to recall and, with respect to optimizing field retrieval settings, further result in significant precision gains.

  13. Reference priors for high energy physics

    SciTech Connect

    Demortier, Luc; Jain, Supriya; Prosper, Harrison B.

    2010-08-01

    Bayesian inferences in high energy physics often use uniform prior distributions for parameters about which little or no information is available before data are collected. The resulting posterior distributions are therefore sensitive to the choice of parametrization for the problem and may even be improper if this choice is not carefully considered. Here we describe an extensively tested methodology, known as reference analysis, which allows one to construct parametrization-invariant priors that embody the notion of minimal informativeness in a mathematically well-defined sense. We apply this methodology to general cross section measurements and show that it yields sensible results. A recent measurement of the single-top quark cross section illustrates the relevant techniques in a realistic situation.

  14. Image Reconstruction Using Analysis Model Prior

    PubMed Central

    Han, Yu; Du, Huiqian; Lam, Fan; Mei, Wenbo; Fang, Liping

    2016-01-01

    The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims. PMID:27379171

  15. Transformational Learning through Prior Learning Assessment

    ERIC Educational Resources Information Center

    Stevens, Karen; Gerber, Dan; Hendra, Rick

    2010-01-01

    Upon graduation from University Without Walls (UWW), Robin said, "During first semester you told us that if we allowed it to, this experience [writing a prior learning portfolio] would change us. I was so angry with you for saying that because I liked who I was and didn't want to change. But you were right. And I'm glad." For the past 39 years the…

  16. Diversity priors for learning early visual features.

    PubMed

    Xiong, Hanchen; Rodríguez-Sánchez, Antonio J; Szedmak, Sandor; Piater, Justus

    2015-01-01

    This paper investigates how utilizing diversity priors can discover early visual features that resemble their biological counterparts. The study is mainly motivated by the sparsity and selectivity of activations of visual neurons in area V1. Most previous work on computational modeling emphasizes selectivity or sparsity independently. However, we argue that selectivity and sparsity are just two epiphenomena of the diversity of receptive fields, which has been rarely exploited in learning. In this paper, to verify our hypothesis, restricted Boltzmann machines (RBMs) are employed to learn early visual features by modeling the statistics of natural images. Considering RBMs as neural networks, the receptive fields of neurons are formed by the inter-weights between hidden and visible nodes. Due to the conditional independence in RBMs, there is no mechanism to coordinate the activations of individual neurons or the whole population. A diversity prior is introduced in this paper for training RBMs. We find that the diversity prior indeed can assure simultaneously sparsity and selectivity of neuron activations. The learned receptive fields yield a high degree of biological similarity in comparison to physiological data. Also, corresponding visual features display a good generative capability in image reconstruction. PMID:26321941

  17. Entropic Priors and Bayesian Model Selection

    NASA Astrophysics Data System (ADS)

    Brewer, Brendon J.; Francis, Matthew J.

    2009-12-01

    We demonstrate that the principle of maximum relative entropy (ME), used judiciously, can ease the specification of priors in model selection problems. The resulting effect is that models that make sharp predictions are disfavoured, weakening the usual Bayesian ``Occam's Razor.'' This is illustrated with a simple example involving what Jaynes called a ``sure thing'' hypothesis. Jaynes' resolution of the situation involved introducing a large number of alternative ``sure thing'' hypotheses that were possible before we observed the data. However, in more complex situations, it may not be possible to explicitly enumerate large numbers of alternatives. The entropic priors formalism produces the desired result without modifying the hypothesis space or requiring explicit enumeration of alternatives; all that is required is a good model for the prior predictive distribution for the data. This idea is illustrated with a simple rigged-lottery example, and we outline how this idea may help to resolve a recent debate amongst cosmologists: is dark energy a cosmological constant, or has it evolved with time in some way? And how shall we decide, when the data are in?

  18. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

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

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  19. Vaginal Absorption of Penicillin.

    PubMed

    Rock, J; Barker, R H; Bacon, W B

    1947-01-01

    Except during the last two months of pregnancy, penicillin is easily absorbed from cocoa butter suppositories in the vagina, ordinarily to give therapeutic blood levels for from 4 to 6 hours. Penicillin in the dosage used seems to have a good effect on vaginal infections. In nonpregnant women, during the ovulation phase, considered as including days 14 +/- 2 in the ordinary menstrual cycle of about 28 days, absorption seemed to be somewhat diminished. Higher levels were found in patients who were near the end of their menstrual cycles and in two patients who were menopausal. Patients who were very near term absorbed little or no penicillin, whereas patients 10 days post partum showed excellent absorption.

  20. Photothermal absorption correlation spectroscopy.

    PubMed

    Octeau, Vivien; Cognet, Laurent; Duchesne, Laurence; Lasne, David; Schaeffer, Nicolas; Fernig, David G; Lounis, Brahim

    2009-02-24

    Fluorescence correlation spectroscopy (FCS) is a popular technique, complementary to cell imaging for the investigation of dynamic processes in living cells. Based on fluorescence, this single molecule method suffers from artifacts originating from the poor fluorophore photophysics: photobleaching, blinking, and saturation. To circumvent these limitations we present here a new correlation method called photothermal absorption correlation spectroscopy (PhACS) which relies on the absorption properties of tiny nano-objects. PhACS is based on the photothermal heterodyne detection technique and measures akin FCS, the time correlation function of the detected signals. Application of this technique to the precise determination of the hydrodynamic sizes of different functionalized gold nanoparticles are presented, highlighting the potential of this method. PMID:19236070

  1. THE ABSORPTION OF ADRENALIN

    PubMed Central

    Lyon, D. Murray

    1923-01-01

    1. Adrenalin solution given subcutaneously is usually rapidly absorbed, probably by lymphatic channels. 2. The speed of this process may be influenced by the circulation rate. 3. The relative amounts of adrenalin at any moment unabsorbed at the site of inoculation, carried in the circulating fluids, and taken up by the reacting tissues can be calculated from figures extracted from the curve of the blood pressure changes. The relative rates of transference of adrenalin into the blood and from the circulation into the tissues can also be estimated. 4. When absorption takes place rapidly a large quantity of the drug comes into action at once and the maximum occurs early, the curve of blood pressure reaches a considerable height, and subsides quickly. When absorption is slow the apex appears later and does not reach so high a level. 5. The response to adrenalin bears a logarithmic relationship to the dose employed and a method of allowing for this is indicated. PMID:19868816

  2. Calibration of UV/Vis spectrophotometers: A review and comparison of different methods to estimate TSS and total and dissolved COD concentrations in sewers, WWTPs and rivers.

    PubMed

    Lepot, Mathieu; Torres, Andres; Hofer, Thomas; Caradot, Nicolas; Gruber, Günter; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

    2016-09-15

    UV/Vis spectrophotometers have been used for one decade to monitor water quality in various locations: sewers, rivers, wastewater treatment plants (WWTPs), tap water networks, etc. Resulting equivalent concentrations of interest can be estimated by three ways: i) by manufacturer global calibration; ii) by local calibration based on the provided global calibration and grab sampling; iii) by advanced calibration looking for relations between UV/Vis spectra and corresponding concentrations from grab sampling. However, no study has compared the applied methods so far. This collaborative work presents a comparison between five different methods. A Linear Regression (LR), Support Vector Machine (SVM), EVOlutionary algorithm method (EVO) and Partial Least Squares (PLS) have been applied on various data sets (sewers, rivers, WWTPs under dry, wet and all weather conditions) and for three water quality parameters: TSS, COD total and dissolved. Two criteria (r(2) and Root Mean Square Error RMSE) have been calculated - on calibration and verification data subsets - to evaluate accuracy and robustness of the applied methods. Values of criteria have then been statistically analysed for all and separated data sets. Non-consistent outcomes come through this study. According to the Kruskal-Wallis test and RMSEs, PLS and SVM seem to be the best methods. According to uncertainties in laboratory analysis and ranking of methods, LR and EVO appear more robust and sustainable for concentration estimations. Conclusions are mostly independent of water matrices, weather conditions or concentrations investigated.

  3. Assessing Single Particle Soot Photometer and Integrating Sphere/Integrating Sandwich Spectrophotometer measurement techniques for quantifying black carbon concentration in snow

    NASA Astrophysics Data System (ADS)

    Schwarz, J. P.; Doherty, S. J.; Li, F.; Ruggiero, S. T.; Tanner, C. E.; Perring, A. E.; Gao, R. S.; Fahey, D. W.

    2012-11-01

    We evaluate the performance of the Single Particle Soot Photometer (SP2) and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) in quantifying the concentration of refractory black carbon (BC) in snow samples. We find that the SP2 can be used to measure BC mass concentration in snow with substantially larger uncertainty (60%) than for atmospheric sampling (<30%). Achieving this level of accuracy requires careful assessment of nebulizer performance and SP2 calibration with consideration of the fact that BC in snow can exist in larger sizes than typically observed in the atmosphere. Once these issues are addressed, the SP2 is able to measure the size distribution and mass concentration of BC in the snow. Laboratory comparison of the SP2 and the ISSW revealed significant biases in the estimate of BC concentration from the ISSW when test samples contained dust or non-absorbing particulates. These results suggest that current estimates of BC mass concentration in snow or ice formed from fallen snow using either the SP2 or the ISSW may be associated with significant underestimates of uncertainty.

  4. Calibration of UV/Vis spectrophotometers: A review and comparison of different methods to estimate TSS and total and dissolved COD concentrations in sewers, WWTPs and rivers.

    PubMed

    Lepot, Mathieu; Torres, Andres; Hofer, Thomas; Caradot, Nicolas; Gruber, Günter; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

    2016-09-15

    UV/Vis spectrophotometers have been used for one decade to monitor water quality in various locations: sewers, rivers, wastewater treatment plants (WWTPs), tap water networks, etc. Resulting equivalent concentrations of interest can be estimated by three ways: i) by manufacturer global calibration; ii) by local calibration based on the provided global calibration and grab sampling; iii) by advanced calibration looking for relations between UV/Vis spectra and corresponding concentrations from grab sampling. However, no study has compared the applied methods so far. This collaborative work presents a comparison between five different methods. A Linear Regression (LR), Support Vector Machine (SVM), EVOlutionary algorithm method (EVO) and Partial Least Squares (PLS) have been applied on various data sets (sewers, rivers, WWTPs under dry, wet and all weather conditions) and for three water quality parameters: TSS, COD total and dissolved. Two criteria (r(2) and Root Mean Square Error RMSE) have been calculated - on calibration and verification data subsets - to evaluate accuracy and robustness of the applied methods. Values of criteria have then been statistically analysed for all and separated data sets. Non-consistent outcomes come through this study. According to the Kruskal-Wallis test and RMSEs, PLS and SVM seem to be the best methods. According to uncertainties in laboratory analysis and ranking of methods, LR and EVO appear more robust and sustainable for concentration estimations. Conclusions are mostly independent of water matrices, weather conditions or concentrations investigated. PMID:27295626

  5. iHWG-μNIR: a miniaturised near-infrared gas sensor based on substrate-integrated hollow waveguides coupled to a micro-NIR-spectrophotometer.

    PubMed

    Rohwedder, J J R; Pasquini, C; Fortes, P R; Raimundo, I M; Wilk, A; Mizaikoff, B

    2014-07-21

    A miniaturised gas analyser is described and evaluated based on the use of a substrate-integrated hollow waveguide (iHWG) coupled to a microsized near-infrared spectrophotometer comprising a linear variable filter and an array of InGaAs detectors. This gas sensing system was applied to analyse surrogate samples of natural fuel gas containing methane, ethane, propane and butane, quantified by using multivariate regression models based on partial least square (PLS) algorithms and Savitzky-Golay 1(st) derivative data preprocessing. The external validation of the obtained models reveals root mean square errors of prediction of 0.37, 0.36, 0.67 and 0.37% (v/v), for methane, ethane, propane and butane, respectively. The developed sensing system provides particularly rapid response times upon composition changes of the gaseous sample (approximately 2 s) due the minute volume of the iHWG-based measurement cell. The sensing system developed in this study is fully portable with a hand-held sized analyser footprint, and thus ideally suited for field analysis. Last but not least, the obtained results corroborate the potential of NIR-iHWG analysers for monitoring the quality of natural gas and petrochemical gaseous products. PMID:24867650

  6. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  7. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  8. The role of atomic absorption spectrometry in geochemical exploration

    USGS Publications Warehouse

    Viets, J.G.; O'Leary, R. M.

    1992-01-01

    In this paper we briefly describe the principles of atomic absorption spectrometry (AAS) and the basic hardware components necessary to make measurements of analyte concentrations. Then we discuss a variety of methods that have been developed for the introduction of analyte atoms into the light path of the spectrophotometer. This section deals with sample digestion, elimination of interferences, and optimum production of ground-state atoms, all critical considerations when choosing an AAS method. Other critical considerations are cost, speed, simplicity, precision, and applicability of the method to the wide range of materials sampled in geochemical exploration. We cannot attempt to review all of the AAS methods developed for geological materials but instead will restrict our discussion to some of those appropriate for geochemical exploration. Our background and familiarity are reflected in the methods we discuss, and we have no doubt overlooked many good methods. Our discussion should therefore be considered a starting point in finding the right method for the problem, rather than the end of the search. Finally, we discuss the future of AAS relative to other instrumental techniques and the promising new directions for AAS in geochemical exploration. ?? 1992.

  9. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  10. Determination of soluble aluminium concentration in alkaline humic water using atomic absorption spectrophotometry.

    PubMed

    Nguyen, K L; Lewis, D M; Jolly, M; Robinson, J

    2004-11-01

    The steps of the standard method to determine soluble aluminium concentration are filtering, followed by acidifying, then analysing with the atomic absorption spectrophotometer (AAS). When applied to alkaline humic water, acidification gives rise to the formation of humic acid as a brown particulate matter. Of the total soluble aluminium in the original water, 49-61% forms complexes with the particulate humic acid upon acidification. Although the AAS is capable of detecting the binding aluminium, the particulate nature of humic acid easily induces inaccurate readings as a result of the non-uniform distribution of the particulate matter. A more precise analysis of soluble aluminium concentration of alkaline humic water is shown to be achievable in basicified solutions instead. Basicified solutions keep humic acid in the soluble form; hence maintain the homogeneity of the sample.

  11. Interacting geometric priors for robust multimodel fitting.

    PubMed

    Pham, Trung Thanh; Chin, Tat-Jun; Schindler, Konrad; Suter, David

    2014-10-01

    Recent works on multimodel fitting are often formulated as an energy minimization task, where the energy function includes fitting error and regularization terms, such as low-level spatial smoothness and model complexity. In this paper, we introduce a novel energy with high-level geometric priors that consider interactions between geometric models, such that certain preferred model configurations may be induced.We argue that in many applications, such prior geometric properties are available and should be fruitfully exploited. For example, in surface fitting to point clouds, the building walls are usually either orthogonal or parallel to each other. Our proposed energy function is useful in dealing with unknown distributions of data errors and outliers, which are often the factors leading to biased estimation. Furthermore, the energy can be efficiently minimized using the expansion move method. We evaluate the performance on several vision applications using real data sets. Experimental results show that our method outperforms the state-of-the-art methods without significant increase in computation.

  12. How prior expectations shape multisensory perception.

    PubMed

    Gau, Remi; Noppeney, Uta

    2016-01-01

    The brain generates a representation of our environment by integrating signals from a common source, but segregating signals from different sources. This fMRI study investigated how the brain arbitrates between perceptual integration and segregation based on top-down congruency expectations and bottom-up stimulus-bound congruency cues. Participants were presented audiovisual movies of phonologically congruent, incongruent or McGurk syllables that can be integrated into an illusory percept (e.g. "ti" percept for visual «ki» with auditory /pi/). They reported the syllable they perceived. Critically, we manipulated participants' top-down congruency expectations by presenting McGurk stimuli embedded in blocks of congruent or incongruent syllables. Behaviorally, participants were more likely to fuse audiovisual signals into an illusory McGurk percept in congruent than incongruent contexts. At the neural level, the left inferior frontal sulcus (lIFS) showed increased activations for bottom-up incongruent relative to congruent inputs. Moreover, lIFS activations were increased for physically identical McGurk stimuli, when participants segregated the audiovisual signals and reported their auditory percept. Critically, this activation increase for perceptual segregation was amplified when participants expected audiovisually incongruent signals based on prior sensory experience. Collectively, our results demonstrate that the lIFS combines top-down prior (in)congruency expectations with bottom-up (in)congruency cues to arbitrate between multisensory integration and segregation.

  13. Absorption heat pumps

    NASA Astrophysics Data System (ADS)

    Huhtinen, M.; Heikkilae, M.; Andersson, R.

    1987-03-01

    The aim of the study was to analyze the technical and economic feasibility of absorption heat pumps in Finland. The work was done as a case study: the technical and economic analyses have been carried out for six different cases, where in each the suitable size and type of the heat pump plant and the auxiliary components and connections were specified. The study also detailed the costs concerning the procurement, installation and test runs of the machinery, as well as the savings in energy costs incurred by the introduction of the plant. Conclusions were drawn of the economic viability of the applications studied. The following cases were analyzed: heat recovery from flue gases and productin of district heat in plants using peat, natural gas, and municipal wastes as a fuel. Heat recovery in the pulp and paper industry for the upgrading of pressure of secondary steam and for the heating of white liquor and combustion and drying the air. Heat recovery in a peat-fulled heat and power plant from flue gases that have been used for the drying of peat. According to the study, the absorption heat pump suits best to the production of district heat, when the heat source is the primary energy is steam produced by the boiler. Included in the flue as condensing is the purification of flue gases. Accordingly, benefit is gained on two levels in thick applications. In heat and power plants the use of absorption heat pumps is less economical, due to the fact that the steam used by the pump reduces the production of electricity, which is rated clearly higher than heat.

  14. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  15. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  16. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Karny, M.; Rykaczewski, K. P.; Fijałkowska, A.; Rasco, B. C.; Wolińska-Cichocka, M.; Grzywacz, R. K.; Goetz, K. C.; Miller, D.; Zganjar, E. F.

    2016-11-01

    The design and performance of the Modular Total Absorption Spectrometer built and commissioned at the Oak Ridge National Laboratory is presented. The active volume of the detector is approximately one ton of NaI(Tl), which results in very high full γ energy peak efficiency of 71% at 6 MeV and nearly flat efficiency of around 81.5% for low energy γ-rays between 300 keV and 1 MeV. In addition to the high peak efficiency, the modular construction of the detector permits the use of a γ-coincidence technique in data analysis as well as β-delayed neutron observation.

  17. A Portable Diode Array Spectrophotometer.

    PubMed

    Stephenson, David

    2016-05-01

    A cheap portable visible light spectrometer is presented. The spectrometer uses readily sourced items and could be constructed by anyone with a knowledge of electronics. The spectrometer covers the wavelength range 450-725 nm with a resolution better than 5 nm. The spectrometer uses a diffraction grating to separate wavelengths, which are detected using a 128-element diode array, the output of which is analyzed using a microprocessor. The spectrum is displayed on a small liquid crystal display screen and can be saved to a micro SD card for later analysis. Battery life (2 × AAA) is estimated to be 200 hours. The overall dimensions of the unit are 120 × 65 × 60 mm, and it weighs about 200 g. PMID:27036399

  18. Determination of gold in geologic materials by solvent extraction and atomic-absorption spectrometry

    USGS Publications Warehouse

    Huffman, Claude; Mensik, J.D.; Riley, L.B.

    1967-01-01

    The two methods presented for the determination of traces of gold in geologic materials are the cyanide atomic-absorption method and the fire-assay atomic-absorption method. In the cyanide method gold is leached with a sodium-cyanide solution. The monovalent gold is then oxidized to the trivalent state and concentrated by extracting into methyl isobutyl ketone prior to estimation by atomic absorption. In the fire-assay atomic-absorption method, the gold-silver bead obtained from fire assay is dissolved in nitric and hydrochloric acids. Gold is then concentrated by extracting into methyl isobutyl ketone prior to determination by atomic absorption. By either method concentrations as low as 50 parts per billion of gold can be determined in a 15-gram sample.

  19. Ozone recovery as seen in perspective of the Dobson spectrophotometer measurements at Belsk (52°N, 21°E) in the period 1963-2008

    NASA Astrophysics Data System (ADS)

    Krzyścin, Janusz W.; Rajewska-Więch, Bonawentura

    2009-12-01

    The total ozone monthly means derived from measurements by the Dobson spectrophotometer at Belsk (52°N, 21°E) and satellite observations over central and midlatitudinal Europe are analyzed for the long-term changes between 1995 and 2008. Standard explanatory variables representing physical and chemical processes known to influence the ozone distribution are considered. The potential proxies are: atmospheric loading by the ozone depleting substances characterized by the equivalent effective stratospheric chlorine (EESC) time series, various drivers of ozone dynamical variability including solar cycle, teleconnection patterns, temperature at 50 hPa, and pressure at the tropopause level. The multivariate adaptive regression splines (MARS) methodology is used to find optimal set of the explanatory variables and shape of the anthropogenic trend curve. Following options for the trend curve are examined: proportional to EESC, piecewise linear (with the turning points in 1980 and 1995), and selected from a smooth curve fit to the total ozone time series having "natural variations" removed. Statistical estimates and their uncertainties are calculated using block bootstrapping. The analyses indicate that ozone over Belsk, in central Europe, and in midlatitudinal Europe reaches at least first stage of recovery as defined by the World Meteorological Organization: a statistically significant reduction in the rate of decline. Model using the EESC time series as a proxy for the anthropogenic trend pattern yields even the second stage, i.e., a positive trend in time series that remains after removal dynamical signal from the analyzed data. Substantial seasonal dependent long-term ozone oscillations by the dynamical drivers are revealed causing estimation of the ozone recovery time even more uncertain.

  20. U.S. EPA Brewer spectrophotometer network and the USDA UVB monitoring and research program: data comparison from co-located instruments

    NASA Astrophysics Data System (ADS)

    Kimlin, Michael G.; Slusser, James R.; Schallhorn, Kathryn A.; Meltzer, Richard S.

    2003-11-01

    Several ground based ultraviolet (UV) monitoring networks exist in the United States, each of which is unique in the instrumentation employed for measurements. Two of these UV networks are the US EPA"s Brewer Spectrophotometer network and the USDA"s UVB Monitoring network, with a combined instrument total of 52 sites throughout the mainland USA, US territories and some overseas locations. The Brewer records full sky spectra from 287-363nm with 0.5nm resolution whereas the USDA instrument is a broadband device that measures broadband erythemally weighted UV data over a number of bands in the UV. To date, limited comparisons of data collected from these networks have been analyzed for comparative and quality assurance (QA) purposes. The data used in this paper is taken from sites where instruments from each program are co-located, namely, BigBend National Park, Texas and Everglades National Park, Florida. In order to reduce the contribution of errors in the Brewer-based instruments, the raw data has been corrected for stray light rejection, the angular response of the full sky diffuser, the temperature dependence of the instruments and the temporal variation. This reduces the estimated errors of the absolute irradiance values of each Brewer spectral measurement to approximately +/-5%. The estimated uncertainty of the USDA instruments is also +/-5%. Uncertainty is comprised of (1) standard lamp measurement errors, (2) spectral response determination and (3) the angular response of the diffuser. In this paper, we perform spectrally resolved comparisons between the Brewer UV irradiance measurements and the data collected by the broadband erythemal UV meters at co-located sites between 1997 through to 2002.

  1. Light absorption properties and absorption budget of Southeast Pacific waters

    NASA Astrophysics Data System (ADS)

    Bricaud, Annick; Babin, Marcel; Claustre, Hervé; Ras, JoséPhine; TièChe, Fanny

    2010-08-01

    Absorption coefficients of phytoplankton, nonalgal particles (NAPs), and colored dissolved organic matter (CDOM), and their relative contributions to total light absorption, are essential variables for bio-optical and biogeochemical models. However, their actual variations in the open ocean remain poorly documented, particularly for clear waters because of the difficulty in measuring very low absorption coefficients. The Biogeochemistry and Optics South Pacific Experiment (BIOSOPE) cruise investigated a large range of oceanic regimes, from mesotrophic waters around the Marquesas Islands to hyperoligotrophic waters in the subtropical gyre and eutrophic waters in the upwelling area off Chile. The spectral absorption coefficients of phytoplankton and NAPs were determined using the filter technique, while the CDOM absorption coefficients were measured using a 2 m capillary waveguide. Over the whole transect, the absorption coefficients of both dissolved and particulate components covered approximately two orders of magnitude; in the gyre, they were among the lowest ever reported for open ocean waters. In the oligotrophic and mesotrophic waters, absorption coefficients of phytoplankton and NAPs were notably lower than those measured in other oceanic areas with similar chlorophyll contents, indicating some deviation from the standard chlorophyll-absorption relationships. The contribution of absorption by NAPs to total particulate absorption showed large vertical and horizontal variations. CDOM absorption coefficients covaried with algal biomass, albeit with a high scatter. The spectral slopes of both NAP and CDOM absorption revealed structured spatial variability in relation with the trophic conditions. The relative contributions of each component to total nonwater absorption were (at a given wavelength) weakly variable over the transect, at least within the euphotic layer.

  2. Prior expectations facilitate metacognition for perceptual decision.

    PubMed

    Sherman, M T; Seth, A K; Barrett, A B; Kanai, R

    2015-09-01

    The influential framework of 'predictive processing' suggests that prior probabilistic expectations influence, or even constitute, perceptual contents. This notion is evidenced by the facilitation of low-level perceptual processing by expectations. However, whether expectations can facilitate high-level components of perception remains unclear. We addressed this question by considering the influence of expectations on perceptual metacognition. To isolate the effects of expectation from those of attention we used a novel factorial design: expectation was manipulated by changing the probability that a Gabor target would be presented; attention was manipulated by instructing participants to perform or ignore a concurrent visual search task. We found that, independently of attention, metacognition improved when yes/no responses were congruent with expectations of target presence/absence. Results were modeled under a novel Bayesian signal detection theoretic framework which integrates bottom-up signal propagation with top-down influences, to provide a unified description of the mechanisms underlying perceptual decision and metacognition.

  3. NMR spectral analysis using prior knowledge

    NASA Astrophysics Data System (ADS)

    Kasai, Takuma; Nagata, Kenji; Okada, Masato; Kigawa, Takanori

    2016-03-01

    Signal assignment is a fundamental step for analyses of protein structure and dynamics with nuclear magnetic resonance (NMR). Main-chain signal assignment is achieved with a sequential assignment method and/or an amino-acid selective stable isotope labeling (AASIL) method. Combinatorial selective labeling (CSL) methods, as well as our labeling strategy, stable isotope encoding (SiCode), were developed to reduce the required number of labeled samples, since one of the drawbacks of AASIL is that many samples are needed. Signal overlapping in NMR spectra interferes with amino-acid determination by CSL and SiCode. Since spectral deconvolution by peak fitting with a gradient method cannot resolve closely overlapped signals, we developed a new method to perform both peak fitting and amino acid determination simultaneously, with a replica exchange Monte Carlo method, incorporating prior knowledge of stable-isotope labeling ratios and the amino-acid sequence of the protein.

  4. The prior statistics of object colors.

    PubMed

    Koenderink, Jan J

    2010-02-01

    The prior statistics of object colors is of much interest because extensive statistical investigations of reflectance spectra reveal highly non-uniform structure in color space common to several very different databases. This common structure is due to the visual system rather than to the statistics of environmental structure. Analysis involves an investigation of the proper sample space of spectral reflectance factors and of the statistical consequences of the projection of spectral reflectances on the color solid. Even in the case of reflectance statistics that are translationally invariant with respect to the wavelength dimension, the statistics of object colors is highly non-uniform. The qualitative nature of this non-uniformity is due to trichromacy.

  5. Improving semantic scene understanding using prior information

    NASA Astrophysics Data System (ADS)

    Laddha, Ankit; Hebert, Martial

    2016-05-01

    Perception for ground robot mobility requires automatic generation of descriptions of the robot's surroundings from sensor input (cameras, LADARs, etc.). Effective techniques for scene understanding have been developed, but they are generally purely bottom-up in that they rely entirely on classifying features from the input data based on learned models. In fact, perception systems for ground robots have a lot of information at their disposal from knowledge about the domain and the task. For example, a robot in urban environments might have access to approximate maps that can guide the scene interpretation process. In this paper, we explore practical ways to combine such prior information with state of the art scene understanding approaches.

  6. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  7. Diffusion-based spatial priors for imaging

    PubMed Central

    Harrison, L.M.; Penny, W.; Ashburner, J.; Trujillo-Barreto, N.; Friston, K.J.

    2007-01-01

    We describe a Bayesian scheme to analyze images, which uses spatial priors encoded by a diffusion kernel, based on a weighted graph Laplacian. This provides a general framework to formulate a spatial model, whose parameters can be optimized. The application we have in mind is a spatiotemporal model for imaging data. We illustrate the method on a random effects analysis of fMRI contrast images from multiple subjects; this simplifies exposition of the model and enables a clear description of its salient features. Typically, imaging data are smoothed using a fixed Gaussian kernel as a pre-processing step before applying a mass-univariate statistical model (e.g., a general linear model) to provide images of parameter estimates. An alternative is to include smoothness in a multivariate statistical model (Penny, W.D., Trujillo-Barreto, N.J., Friston, K.J., 2005. Bayesian fMRI time series analysis with spatial priors. Neuroimage 24, 350–362). The advantage of the latter is that each parameter field is smoothed automatically, according to a measure of uncertainty, given the data. In this work, we investigate the use of diffusion kernels to encode spatial correlations among parameter estimates. Nonlinear diffusion has a long history in image processing; in particular, flows that depend on local image geometry (Romeny, B.M.T., 1994. Geometry-driven Diffusion in Computer Vision. Kluwer Academic Publishers) can be used as adaptive filters. This can furnish a non-stationary smoothing process that preserves features, which would otherwise be lost with a fixed Gaussian kernel. We describe a Bayesian framework that incorporates non-stationary, adaptive smoothing into a generative model to extract spatial features in parameter estimates. Critically, this means adaptive smoothing becomes an integral part of estimation and inference. We illustrate the method using synthetic and real fMRI data. PMID:17869542

  8. The melanosome: threshold temperature for explosive vaporization and internal absorption coefficient during pulsed laser irradiation.

    PubMed

    Jacques, S L; McAuliffe, D J

    1991-06-01

    The explosive vaporization of melanosomes in situ in skin during pulsed laser irradiation (pulse duration less than 1 microsecond) is observed as a visible whitening of the superficial epidermal layer due to stratum corneum disruption. In this study, the ruby laser (694 nm) was used to determine the threshold radiant exposure, H0 (J/cm2), required to elicit whitening for in vitro black (Negroid) human skin samples which were pre-equilibrated at an initial temperature, Ti, of 0, 20, or 50 degrees C. A plot of H0 vs Ti yields a straight line whose x-intercept indicates the threshold temperature of explosive vaporization to be 112 +/- 7 degrees C (SD, N = 3). The slope, delta H0/delta Ti, specifies the internal absorption coefficient, mua, within the melanosome: mua = -rho C/(slope(1 + 7.1 Rd)), where rho C is the product of density and specific heat, and Rd is the total diffuse reflectance from the skin. A summary of the absorption spectrum (mua) for the melanosome interior (351-1064 nm) is presented based on H0 data from this study and the literature. The in vivo absorption spectrum (380-820 nm) for human epidermal melanin was measured by an optical fiber spectrophotometer and is compared with the melanosome spectrum. PMID:1886936

  9. The melanosome: threshold temperature for explosive vaporization and internal absorption coefficient during pulsed laser irradiation.

    PubMed

    Jacques, S L; McAuliffe, D J

    1991-06-01

    The explosive vaporization of melanosomes in situ in skin during pulsed laser irradiation (pulse duration less than 1 microsecond) is observed as a visible whitening of the superficial epidermal layer due to stratum corneum disruption. In this study, the ruby laser (694 nm) was used to determine the threshold radiant exposure, H0 (J/cm2), required to elicit whitening for in vitro black (Negroid) human skin samples which were pre-equilibrated at an initial temperature, Ti, of 0, 20, or 50 degrees C. A plot of H0 vs Ti yields a straight line whose x-intercept indicates the threshold temperature of explosive vaporization to be 112 +/- 7 degrees C (SD, N = 3). The slope, delta H0/delta Ti, specifies the internal absorption coefficient, mua, within the melanosome: mua = -rho C/(slope(1 + 7.1 Rd)), where rho C is the product of density and specific heat, and Rd is the total diffuse reflectance from the skin. A summary of the absorption spectrum (mua) for the melanosome interior (351-1064 nm) is presented based on H0 data from this study and the literature. The in vivo absorption spectrum (380-820 nm) for human epidermal melanin was measured by an optical fiber spectrophotometer and is compared with the melanosome spectrum.

  10. [Study on experiment of absorption spectroscopy detection of pesticide residues of carbendazim in orange juice].

    PubMed

    Ji, Ren-Dong; Chen, Meng-Lan; Zhao, Zhi-Min; Zhu, Xing-Yue; Wang, Le-Xin; Liu, Quan-Jin

    2014-03-01

    Absorption spectra were studied for the carbendazim, in the mixed solution of orange juice and carbendazim using spectrophotometer. The most intensive characteristic peak (285 nm) was found in the spectrum of carbendazim standard solution. Compared with the carbendazim drug solution, the peak position of absorption spectrum has the blue shift (285-280 nm) when carbendazim (0.28 mg x mL(-1))was added in the orange juice. So that we can conclude that interaction happened between the orange juice and carbendazim. Through the method of least squares fitting, the prediction models between the absorbance of orange juice and carbendazim content was obtained with a good linear relationship. The linear function model was: I = 2.41 + 9.26x, the correlation coefficient was 0.996, and the recovery was: 81%-102%. According to the regression model, we can obtain the amount of carbendazim pesticide residues in orange juice. It was verified that the method of using ultraviolet-visible absorption spectra was feasible to detect the carbendazim residues in orange juice. The result proved that it is possible to detect pesticide residues of carbendazim in orange juice, and it can meet the needs of rapid analysis. This study provides a new way for the detection of pesticide residues.

  11. Subcortical structure segmentation using probabilistic atlas priors

    NASA Astrophysics Data System (ADS)

    Gouttard, Sylvain; Styner, Martin; Joshi, Sarang; Smith, Rachel G.; Cody Hazlett, Heather; Gerig, Guido

    2007-03-01

    The segmentation of the subcortical structures of the brain is required for many forms of quantitative neuroanatomic analysis. The volumetric and shape parameters of structures such as lateral ventricles, putamen, caudate, hippocampus, pallidus and amygdala are employed to characterize a disease or its evolution. This paper presents a fully automatic segmentation of these structures via a non-rigid registration of a probabilistic atlas prior and alongside a comprehensive validation. Our approach is based on an unbiased diffeomorphic atlas with probabilistic spatial priors built from a training set of MR images with corresponding manual segmentations. The atlas building computes an average image along with transformation fields mapping each training case to the average image. These transformation fields are applied to the manually segmented structures of each case in order to obtain a probabilistic map on the atlas. When applying the atlas for automatic structural segmentation, an MR image is first intensity inhomogeneity corrected, skull stripped and intensity calibrated to the atlas. Then the atlas image is registered to the image using an affine followed by a deformable registration matching the gray level intensity. Finally, the registration transformation is applied to the probabilistic maps of each structures, which are then thresholded at 0.5 probability. Using manual segmentations for comparison, measures of volumetric differences show high correlation with our results. Furthermore, the dice coefficient, which quantifies the volumetric overlap, is higher than 62% for all structures and is close to 80% for basal ganglia. The intraclass correlation coefficient computed on these same datasets shows a good inter-method correlation of the volumetric measurements. Using a dataset of a single patient scanned 10 times on 5 different scanners, reliability is shown with a coefficient of variance of less than 2 percents over the whole dataset. Overall, these validation

  12. Intestinal calcium absorption in rats is stimulated by dietary lactulose and other resistant sugars.

    PubMed

    Brommage, R; Binacua, C; Antille, S; Carrié, A L

    1993-12-01

    Lactulose is a disaccharide analogue of lactose that is resistant to metabolism in the small intestine but not in the large intestine. The effects of lactulose and other sugars on intestinal Ca absorption were determined from the decrease in the 47Ca:47 Sc ratio between diet and feces after feeding male rats diets containing these sugars during a single night. Dietary lactulose was more potent than lactose in stimulating Ca absorption and was effective between 5 and 38 wk of age. The component sugars of lactulose, galactose and fructose, did not influence Ca absorption when provided together at concentrations equimolar to that of lactulose. The stimulation of Ca absorption by dietary lactulose increased as dietary Ca concentration was raised and was not influenced by prior injections of calcitriol. Lactulose must be present in the same meal as Ca to stimulate Ca absorption, but this stimulation was lost if the rats were fed lactulose continuously for 2 or 7 d prior to the test diet. Other sugars thought to be poorly absorbed in the small intestine (xylitol, lactobionate, arabinose, raffinose, pyroglutamate, sorbitol, gluconate and raftilose) stimulated Ca absorption to an identical extent as lactulose. Cecectomy did not influence the enhancement of Ca absorption by lactulose. These results indicate that sugars resistant to metabolism and absorption in the small intestine but not the large intestine stimulate Ca absorption in the small intestine.

  13. Absorption mode Fourier transform electrostatic linear ion trap mass spectrometry.

    PubMed

    Hilger, Ryan T; Wyss, Phillip J; Santini, Robert E; McLuckey, Scott A

    2013-09-01

    In Fourier transform mass spectrometry, it is well-known that plotting the spectrum in absorption mode rather than magnitude mode has several advantages. However, magnitude spectra remain commonplace due to difficulties associated with determining the phase of each frequency at the onset of data acquisition, which is required for generating absorption spectra. The phasing problem for electrostatic traps is much simpler than for Fourier transform ion cyclotron resonance (FTICR) instruments, which greatly simplifies the generation of absorption spectra. Here, we present a simple method for generating absorption spectra from a Fourier transform electrostatic linear ion trap mass spectrometer. The method involves time shifting the data prior to Fourier transformation in order to synchronize the onset of data acquisition with the moment of ion acceleration into the electrostatic trap. Under these conditions, the initial phase of each frequency at the onset of data acquisition is zero. We demonstrate that absorption mode provides a 1.7-fold increase in resolution (full width at half maximum, fwhm) as well as reduced peak tailing. We also discuss methodology that may be applied to unsynchronized data in order to determine the time shift required to generate an absorption spectrum.

  14. Percutaneous absorption in preterm infants.

    PubMed

    West, D P; Halket, J M; Harvey, D R; Hadgraft, J; Solomon, L M; Harper, J I

    1987-11-01

    The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function. PMID:3422856

  15. Putting Priors in Mixture Density Mercer Kernels

    NASA Technical Reports Server (NTRS)

    Srivastava, Ashok N.; Schumann, Johann; Fischer, Bernd

    2004-01-01

    This paper presents a new methodology for automatic knowledge driven data mining based on the theory of Mercer Kernels, which are highly nonlinear symmetric positive definite mappings from the original image space to a very high, possibly infinite dimensional feature space. We describe a new method called Mixture Density Mercer Kernels to learn kernel function directly from data, rather than using predefined kernels. These data adaptive kernels can en- code prior knowledge in the kernel using a Bayesian formulation, thus allowing for physical information to be encoded in the model. We compare the results with existing algorithms on data from the Sloan Digital Sky Survey (SDSS). The code for these experiments has been generated with the AUTOBAYES tool, which automatically generates efficient and documented C/C++ code from abstract statistical model specifications. The core of the system is a schema library which contains template for learning and knowledge discovery algorithms like different versions of EM, or numeric optimization methods like conjugate gradient methods. The template instantiation is supported by symbolic- algebraic computations, which allows AUTOBAYES to find closed-form solutions and, where possible, to integrate them into the code. The results show that the Mixture Density Mercer-Kernel described here outperforms tree-based classification in distinguishing high-redshift galaxies from low- redshift galaxies by approximately 16% on test data, bagged trees by approximately 7%, and bagged trees built on a much larger sample of data by approximately 2%.

  16. Prolonged Instability Prior to a Regime Shift

    PubMed Central

    Spanbauer, Trisha L.; Allen, Craig R.; Angeler, David G.; Eason, Tarsha; Fritz, Sherilyn C.; Garmestani, Ahjond S.; Nash, Kirsty L.; Stone, Jeffery R.

    2014-01-01

    Regime shifts are generally defined as the point of ‘abrupt’ change in the state of a system. However, a seemingly abrupt transition can be the product of a system reorganization that has been ongoing much longer than is evident in statistical analysis of a single component of the system. Using both univariate and multivariate statistical methods, we tested a long-term high-resolution paleoecological dataset with a known change in species assemblage for a regime shift. Analysis of this dataset with Fisher Information and multivariate time series modeling showed that there was a∼2000 year period of instability prior to the regime shift. This period of instability and the subsequent regime shift coincide with regional climate change, indicating that the system is undergoing extrinsic forcing. Paleoecological records offer a unique opportunity to test tools for the detection of thresholds and stable-states, and thus to examine the long-term stability of ecosystems over periods of multiple millennia. PMID:25280010

  17. Washing of waste prior to landfilling.

    PubMed

    Cossu, Raffaello; Lai, Tiziana

    2012-05-01

    The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment.

  18. Theoretical priors on modified growth parametrisations

    SciTech Connect

    Song, Yong-Seon; Hollenstein, Lukas; Caldera-Cabral, Gabriela; Koyama, Kazuya E-mail: Lukas.Hollenstein@unige.ch E-mail: Kazuya.Koyama@port.ac.uk

    2010-04-01

    Next generation surveys will observe the large-scale structure of the Universe with unprecedented accuracy. This will enable us to test the relationships between matter over-densities, the curvature perturbation and the Newtonian potential. Any large-distance modification of gravity or exotic nature of dark energy modifies these relationships as compared to those predicted in the standard smooth dark energy model based on General Relativity. In linear theory of structure growth such modifications are often parameterised by virtue of two functions of space and time that enter the relation of the curvature perturbation to, first, the matter over- density, and second, the Newtonian potential. We investigate the predictions for these functions in Brans-Dicke theory, clustering dark energy models and interacting dark energy models. We find that each theory has a distinct path in the parameter space of modified growth. Understanding these theoretical priors on the parameterisations of modified growth is essential to reveal the nature of cosmic acceleration with the help of upcoming observations of structure formation.

  19. Pitch perception prior to cortical maturation

    NASA Astrophysics Data System (ADS)

    Lau, Bonnie K.

    Pitch perception plays an important role in many complex auditory tasks including speech perception, music perception, and sound source segregation. Because of the protracted and extensive development of the human auditory cortex, pitch perception might be expected to mature, at least over the first few months of life. This dissertation investigates complex pitch perception in 3-month-olds, 7-month-olds and adults -- time points when the organization of the auditory pathway is distinctly different. Using an observer-based psychophysical procedure, a series of four studies were conducted to determine whether infants (1) discriminate the pitch of harmonic complex tones, (2) discriminate the pitch of unresolved harmonics, (3) discriminate the pitch of missing fundamental melodies, and (4) have comparable sensitivity to pitch and spectral changes as adult listeners. The stimuli used in these studies were harmonic complex tones, with energy missing at the fundamental frequency. Infants at both three and seven months of age discriminated the pitch of missing fundamental complexes composed of resolved and unresolved harmonics as well as missing fundamental melodies, demonstrating perception of complex pitch by three months of age. More surprisingly, infants in both age groups had lower pitch and spectral discrimination thresholds than adult listeners. Furthermore, no differences in performance on any of the tasks presented were observed between infants at three and seven months of age. These results suggest that subcortical processing is not only sufficient to support pitch perception prior to cortical maturation, but provides adult-like sensitivity to pitch by three months.

  20. Capitation payments based on prior hospitalizations.

    PubMed

    van Vliet, R C; van de Ven, W P

    1993-07-01

    In many countries the concept of capitating health care insurers is receiving increasing attention. In a competitive environment, capitation should induce insurers to concentrate more on cost containment instead of indulging in risk selection. The necessary premium-replacing capitation payments should account for predictable variations in annual per-person health care expenditures as far as these are related to health status. Various studies have shown that crude capitation models based on e.g. age, sex and place of residence, do not reflect expected costs accurately. This implies inefficient pricing possibly leading to risk selection and windfall profits or losses for insurers, thereby undermining the objectives of a capitation system. Using Dutch micro data on some 200,000 individuals, this article stimulates various alternative capitation models based on, among others, diagnostic information from previous hospitalizations. Results suggest that the problems of both risk selection and windfall profits/losses may be mitigated substantially by using this type of information together with data on prior costs. These results are not only relevant for situations where competing insurers are capitated, as intended in the Netherlands, but also when providers are capitated, as in the UK, or when HMOs are capitated, as in the US.

  1. Cathodic ARC surface cleaning prior to brazing

    SciTech Connect

    Dave, V. R.; Hollis, K. J.; Castro, R. G.; Smith, F. M.; Javernick, D. A.

    2002-01-01

    Surface cleanliness is one the critical process variables in vacuum furnace brazing operations. For a large number of metallic components, cleaning is usually accomplished either by water-based alkali cleaning, but may also involve acid etching or solvent cleaning / rinsing. Nickel plating may also be necessary to ensure proper wetting. All of these cleaning or plating technologies have associated waste disposal issues, and this article explores an alternative cleaning process that generates minimal waste. Cathodic arc, or reserve polarity, is well known for welding of materials with tenacious oxide layers such as aluminum alloys. In this work the reverse polarity effect is used to clean austenitic stainless steel substrates prior to brazing with Ag-28%Cu. This cleaning process is compared to acid pickling and is shown to produce similar wetting behavior as measured by dynamic contact angle experiments. Additionally, dynamic contact angle measurements with water drops are conducted to show that cathodic arc cleaning can remove organic contaminants as well. The process does have its limitations however, and alloys with high titanium and aluminum content such as nickel-based superalloys may still require plating to ensure adequate wetting.

  2. Washing of waste prior to landfilling.

    PubMed

    Cossu, Raffaello; Lai, Tiziana

    2012-05-01

    The main impact produced by landfills is represented by the release of leachate emissions. Waste washing treatment has been investigated to evaluate its efficiency in reducing the waste leaching fraction prior to landfilling. The results of laboratory-scale washing tests applied to several significant residues from integrated management of solid waste are presented in this study, specifically: non-recyclable plastics from source separation, mechanical-biological treated municipal solid waste and a special waste, automotive shredded residues. Results obtained demonstrate that washing treatment contributes towards combating the environmental impacts of raw wastes. Accordingly, a leachate production model was applied, leading to the consideration that the concentrations of chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN), parameters of fundamental importance in the characterization of landfill leachate, from a landfill containing washed wastes, are comparable to those that would only be reached between 90 and 220years later in the presence of raw wastes. The findings obtained demonstrated that washing of waste may represent an effective means of reducing the leachable fraction resulting in a consequent decrease in landfill emissions. Further studies on pilot scale are needed to assess the potential for full-scale application of this treatment. PMID:22245736

  3. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  4. Quantitative receptor autoradiography: tissue defatting eliminates differential self-absorption of tritium radiation in gray and white matter of brain.

    PubMed

    Herkenham, M; Sokoloff, L

    1984-11-12

    A four-fold greater absorption (quenching) of tritium emissions by white matter relative to gray matter produces a false 'contrast' effect in autoradiographs of 3H-ligand binding to brain sections. The differential absorption is eliminated by tissue defatting prior to autoradiographic exposure.

  5. 13 CFR 305.14 - Occupancy prior to completion.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... COMMERCE PUBLIC WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.14 Occupancy prior to completion. Occupancy of any part of the Project prior to final acceptance is entirely...

  6. 13 CFR 305.14 - Occupancy prior to completion.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... COMMERCE PUBLIC WORKS AND ECONOMIC DEVELOPMENT INVESTMENTS Requirements for Approved Projects § 305.14 Occupancy prior to completion. Occupancy of any part of the Project prior to final acceptance is entirely...

  7. 29 CFR 18.613 - Prior statements of witnesses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... OFFICE OF ADMINISTRATIVE LAW JUDGES Rules of Evidence Witnesses § 18.613 Prior statements of witnesses.... (b) Extrinsic evidence of prior inconsistent statement of witness. Extrinsic evidence of a...

  8. Scaling relations for galaxies prior to reionization

    SciTech Connect

    Chen, Pengfei; Norman, Michael L.; Xu, Hao; Wise, John H.; O'Shea, Brian W. E-mail: mlnorman@ucsd.edu E-mail: jwise@gatech.edu

    2014-11-10

    The first galaxies in the universe are the building blocks of all observed galaxies. We present scaling relations for galaxies forming at redshifts z ≥ 15 when reionization is just beginning. We utilize the 'Rarepeak' cosmological radiation hydrodynamics simulation that captures the complete star formation history in over 3300 galaxies, starting with massive Population III stars that form in dark matter halos as small as ∼10{sup 6} M {sub ☉}. We make various correlations between the bulk halo quantities, such as virial, gas, and stellar masses and metallicities and their respective accretion rates, quantifying a variety of properties of the first galaxies up to halo masses of 10{sup 9} M {sub ☉}. Galaxy formation is not solely relegated to atomic cooling halos with virial temperatures greater than 10{sup 4} K, where we find a dichotomy in galaxy properties between halos above and below this critical mass scale. Halos below the atomic cooling limit have a stellar mass-halo mass relationship log M {sub *} ≅ 3.5 + 1.3log (M {sub vir}/10{sup 7} M {sub ☉}). We find a non-monotonic relationship between metallicity and halo mass for the smallest galaxies. Their initial star formation events enrich the interstellar medium and subsequent star formation to a median of 10{sup –2} Z {sub ☉} and 10{sup –1.5} Z {sub ☉}, respectively, in halos of total mass 10{sup 7} M {sub ☉}, which is then diluted by metal-poor inflows well beyond Population III pre-enrichment levels of 10{sup –3.5} Z {sub ☉}. The scaling relations presented here can be employed in models of reionization, galaxy formation, and chemical evolution in order to consider these galaxies forming prior to reionization.

  9. Design of the detector to observe the energetic charged particles: a part of the solar X-ray spectrophotometer ChemiX onboard Interhelio-Probe mission

    NASA Astrophysics Data System (ADS)

    Dudnik, Oleksiy; Sylwester, Janusz; Kowalinski, Miroslaw; Bakala, Jaroslaw; Siarkowski, Marek; Evgen Kurbatov, mgr..

    2016-07-01

    -layer detector stack: first two layers consist of silicon detectors; the third one is based on the p-terphenyl scintillation detector coupled with pixelated silicon photomultiplier. Coincidence logic allows collecting systematic data on particle variety and their energy with 1 and/or 10 s time resolutions. Digital processing unit is constructed based on FPGA Actel ProAsic M1A3PE1500, and contains each event processing logic, forms telemetry data and housekeeping frames, communicates with ChemiX digital processing unit and executes received telecommands. In order to increase the reliability and time resource of the BPM its digital processing unit and secondary power supply unit has backup sets. Switching between backup sets is commanded by externally orders. The BPM is capable to sort out in situ abundances of individual particle constituents from electrons up to oxygen nuclei. 1. O.V.Dudnik, E.V.Kurbatov, V.O.Tarasov, L.A.Andryushenko, I.L.Zajtsevsky, J.Sylwester, J.Bąkala, M.Kowaliński. Background particle detector for the solar X-ray photometer ChemiX of space mission "Interhelioprobe": an adjustment of breadboard model modules (in Russian) / ISSN 1561-8889: Kosmichna Nauka I Tekhnologiya, 2015, Vol.21, No.2, P.3-14. 2. O.V.Dudnik, E.V.Kurbatov, J.Sylwester, M.Siarkowski, P.Podgórski, M.Kowaliński. Background Particle Monitor - a part of the solar X-ray spectrophotometer ChemiX: principles of the operation and construction / in: Abstracts of 15th Ukrainian conference on space research, Odesa, Ukraine, August 24-28, 2015, P.80, doi:10.13140/RG.2.1.2284.2649. 3. O.V.Dudnik, E.V.Kurbatov, M.Kowaliński, M.Siarkowski, P.Podgórski, J.Sylwester. Operational features of Background Particle Monitor, a vital part of the solar X-ray spectrophotometer ChemiX / in: Abstract book of the Conference "Progress on EUV&X-ray spectroscopy and imaging II", Wroclaw, Poland, November 17 19, 2015, P.9, doi:10.13140/RG.2.1.1184.3604.

  10. Recognition of Prior and Experiential Learning in European Universities

    ERIC Educational Resources Information Center

    Valk, Aune

    2009-01-01

    This paper focuses on the state of the art for recognition of prior experiential learning in European universities. Although recognition of prior learning and prior experiential learning have been officially stated as being important aims by national ministers of education in their Bologna Process communiques, implementation in the majority of…

  11. How Prior Knowledge Affects Word Identification and Comprehension

    ERIC Educational Resources Information Center

    Priebe, Sarah J.; Keenan, Janice M.; Miller, Amanda C.

    2012-01-01

    While prior knowledge of a passage topic is known to facilitate comprehension, little is known about how it affects word identification. We examined oral reading errors in good and poor readers when reading a passage where they either had prior knowledge of the passage topic or did not. Children who had prior knowledge of the topic were matched on…

  12. Community of Priors: A Bayesian Approach to Consensus Building

    ERIC Educational Resources Information Center

    Hara, Motoaki

    2010-01-01

    Despite having drawn from empirical evidence and cumulative prior expertise in the formulation of research questions as well as study design, each study is treated as a stand-alone product rather than positioned within a sequence of cumulative evidence. While results of prior studies are typically cited within the body of prior literature review,…

  13. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  14. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  15. Summary of prior grain entrapment rescue strategies.

    PubMed

    Roberts, M J; Deboy, G R; Field, W E; Maier, D E

    2011-10-01

    Entrapment in flowable agricultural material continues to be a relevant problem facing both farmers and employees of commercial grain storage and handling operations. While considerable work has been done previously on the causes of entrapment in grain and possible preventative measures, there is little research on the efficacy of current first response or extrication techniques. With the recent introduction of new grain rescue equipment and training programs, it was determined that the need exists to document and summarize prior grain rescue strategies with a view to develop evidence-based recommendations that would enhance the efficacy of the techniques used and reduce the risks to both victims and first responders. Utilizing the Purdue University Agricultural Entrapment Database, all data were queried for information related to extrication of victims from grain entrapments documented over the period 1964-2006. Also analyzed were data from other sources, including public records related to entrapments and information from onsite investigations. Significant findings of this study include the following: (1) between 1964 and 2006, the number of entrapments averaged 16 per year, with the frequency increasing over the last decade; (2) of all cases documented, about 45% resulted in fatality; (3) no less than 44% of entrapments occurred in shelled corn; (4) fatality was the result in 82% of cases where victims were submerged beneath the grain surface, while fatality occurred in 10% of cases where victims were only partially engulfed; (5) the majority of rescues were reported to have been conducted by untrained personnel who were at the scene at the time of entrapment; and (6) in those cases where the rescue strategies were known, 56% involved cutting or punching holes in the side walls of the storage structure, 19% involved utilizing onsite fabricated grain retaining walls to extricate partially entrapped victims, and the use of grain vacuum machines as a rescue

  16. Digital communication constraints in prior space missions

    NASA Technical Reports Server (NTRS)

    Yassine, Nathan K.

    2004-01-01

    Digital communication is crucial for space endeavors. Jt transmits scientific and command data between earth stations and the spacecraft crew. It facilitates communications between astronauts, and provides live coverage during all phases of the mission. Digital communications provide ground stations and spacecraft crew precise data on the spacecraft position throughout the entire mission. Lessons learned from prior space missions are valuable for our new lunar and Mars missions set by our president s speech. These data will save our agency time and money, and set course our current developing technologies. Limitations on digital communications equipment pertaining mass, volume, data rate, frequency, antenna type and size, modulation, format, and power in the passed space missions are of particular interest. This activity is in support of ongoing communication architectural studies pertaining to robotic and human lunar exploration. The design capabilities and functionalities will depend on the space and power allocated for digital communication equipment. My contribution will be gathering these data, write a report, and present it to Communications Technology Division Staff. Antenna design is very carefully studied for each mission scenario. Currently, Phased array antennas are being developed for the lunar mission. Phased array antennas use little power, and electronically steer a beam instead of DC motors. There are 615 patches in the phased array antenna. These patches have to be modified to have high yield. 50 patches were created for testing. My part is to assist in the characterization of these patch antennas, and determine whether or not certain modifications to quartz micro-strip patch radiators result in a significant yield to warrant proceeding with repairs to the prototype 19 GHz ferroelectric reflect-array antenna. This work requires learning how to calibrate an automatic network, and mounting and testing antennas in coaxial fixtures. The purpose of this

  17. Color and depth priors in natural images.

    PubMed

    Su, Che-Chun; Cormack, Lawrence K; Bovik, Alan C

    2013-06-01

    Natural scene statistics have played an increasingly important role in both our understanding of the function and evolution of the human vision system, and in the development of modern image processing applications. Because range (egocentric distance) is arguably the most important thing a visual system must compute (from an evolutionary perspective), the joint statistics between image information (color and luminance) and range information are of particular interest. It seems obvious that where there is a depth discontinuity, there must be a higher probability of a brightness or color discontinuity too. This is true, but the more interesting case is in the other direction--because image information is much more easily computed than range information, the key conditional probabilities are those of finding a range discontinuity given an image discontinuity. Here, the intuition is much weaker; the plethora of shadows and textures in the natural environment imply that many image discontinuities must exist without corresponding changes in range. In this paper, we extend previous work in two ways--we use as our starting point a very high quality data set of coregistered color and range values collected specifically for this purpose, and we evaluate the statistics of perceptually relevant chromatic information in addition to luminance, range, and binocular disparity information. The most fundamental finding is that the probabilities of finding range changes do in fact depend in a useful and systematic way on color and luminance changes; larger range changes are associated with larger image changes. Second, we are able to parametrically model the prior marginal and conditional distributions of luminance, color, range, and (computed) binocular disparity. Finally, we provide a proof of principle that this information is useful by showing that our distribution models improve the performance of a Bayesian stereo algorithm on an independent set of input images. To summarize

  18. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  19. Intestinal Folate Absorption

    PubMed Central

    Olinger, Edward J.; Bertino, Joseph R.; Binder, Henry J.

    1973-01-01

    These studies were designed to determine whether pteroylmonoglutamic acid (PGA) at physiologic concentrations is transported across the small intestine unaltered or is reduced and methylated to the circulating folate form (5-methyltetrahydrofolate [5-MeFH4]) during absorption. [3H]PGA was incubated in vitro on the mucosal side of rat jejunum. Of the folate transferred to the serosal side, the percent identified as 5-MeFH4 by DEAE-Sephadex chromtography was inversely related to the initial mucosa PGA concentration: at 7, 20, and 2,000 nM, 44%, 34%, and 2%, respectively, was converted to 5-MeFH4. In contrast, less than 4% of the folate transferred across ileal mucosa was 5-MeFH4 when the initial mucosa concentration was 20 nM. Specific activity of dihydrofolate (DHF) reductase, the enzyme responsible for converting PGA to tetrahydrofolic acid, was measured in villus homogenates and was significantly greater in the jejunum than in the ileum. 1,000 nM methotrexate (MTX), a DHF reductase inhibitor, markedly inhibited PGA conversion to 5-MeFH4 by the jejunum. Studies of transmural flux, initial rate of mucosal entry (influx) and mucosal accumulation (uptake) of folate were also performed. Although MTX did not alter the influx of PGA, MTX decreased jejunal mucosal uptake but increased transmural movement. Transmural folate movement across ileal mucosa was greater than across jejunal mucosa although mucosal uptake was greater in the jejunum than in the ileum. These results could explain previous studies which have failed to identify conversion of PGA to 5-MeFH4 when intestinal preparations have been exposed to higher and less physiologic concentrations of PGA. Further, these studies suggest that 5-MeFH4 may be retained by the jejunal mucosa. PMID:4727453

  20. The Influence of Prior Knowledge on the Retrieval-Directed Function of Note Taking in Prior Knowledge Activation

    ERIC Educational Resources Information Center

    Wetzels, Sandra A. J.; Kester, Liesbeth; van Merrienboer, Jeroen J. G.; Broers, Nick J.

    2011-01-01

    Background: Prior knowledge activation facilitates learning. Note taking during prior knowledge activation (i.e., note taking directed at retrieving information from memory) might facilitate the activation process by enabling learners to build an external representation of their prior knowledge. However, taking notes might be less effective in…

  1. Marginally specified priors for non-parametric Bayesian estimation

    PubMed Central

    Kessler, David C.; Hoff, Peter D.; Dunson, David B.

    2014-01-01

    Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813

  2. Comparison of STOIC 1989 ground-based lidar, microwave spectrometer, and Dobson spectrophotometer Umkehr ozone profiles with ozone profiles from balloon-borne electrochemical concentration cell ozonesondes

    NASA Astrophysics Data System (ADS)

    Komhyr, W. D.; Connor, B. J.; McDermid, I. S.; McGee, T. J.; Parrish, A. D.; Margitan, J. J.

    1995-05-01

    Ground-based measurements of stratospheric ozone using a Jet Propulsion Laboratory (JPL) lidar, a NASA Goddard Space Flight Center (GSFC) lidar, a Millitech Corporation/NASA Langley Research Center (Millitech/LaRC) microwave spectrometer, and a NOAA Dobson ozone spectrophotometer were compared with in situ measurements made quasi-simultaneously with balloon-borne electrochemical concentration cell (ECC) ozonesondes during 10 days of the Stratospheric Ozone Intercomparison Campaign (STOIC). The campaign was conducted at Table Mountain Observatory, California, during the summer of 1989. ECC ozonesondes were flown by NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) personnel as well as by personnel from the NASA Wallops Island Flight Facility (WFF). Within the altitude range of 20-32 km, ozone measurement precisions were estimated to be ±0.6 to ±1.2% for the JPL lidar, ±0.7% for the GSFC lidar, ±4% for the microwave spectrometer, and ±3% for the NOAA ECC ozonesonde instruments. These precisions decreased in the 32 to 38.6-km altitude range to ±1.3, ±1.5, and ±3% to ±10% for the JPL lidar, GSFC lidar, and the ECC sondes, respectively, but remained at ±4% for the microwave instrument. Ozone measurement accuracies in the 20 to 32 km altitude range were estimated to be ±1.2 to ±2.4% for the JPL lidar, ±1.4% for the GSFC lidar, ±6% for the microwave radiometer, and ±5% for the ECC ozonesondes. The accuracies decreased in the 32 to 38.6-km altitude range to ±2.6, ±3.0, ±7, and 1 ± 4% to -4 ± 10% for the JPL lidar, the GSFC lidar, the microwave spectrometer, and the ECC ozonesondes, respectively. While accuracy estimates for the ECC sondes were obtained by combining random and estimated bias errors, the accuracies for the lidar instruments were obtained by doubling the measurement precision figures, with the assumption that such doubling accounts for systematic errors. Within the altitude range of 20-36 km the mean ozone profiles produced by the

  3. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  4. Absorption to reflection transition in selective solar coatings.

    PubMed

    Olson, Kyle D; Talghader, Joseph J

    2012-07-01

    The optimum transition wavelength between high absorption and low emissivity for selective solar absorbers has been calculated in several prior treatises for an ideal system, where the emissivity is exactly zero in the infrared. However, no real coating can achieve such a low emissivity across the entire infrared with simultaneously high absorption in the visible. An emissivity of even a few percent radically changes the optimum wavelength separating the high and low absorption spectral bands. This behavior is described and calculated for AM0 and AM1.5 solar spectra with an infrared emissivity varying between 0 and 5%. With an emissivity of 5%, solar concentration of 10 times the AM1.5 spectrum the optimum transition wavelength is found to be 1.28 µm and have a 957K equilibrium temperature. To demonstrate typical absorptions in optimized solar selective coatings, a four-layer sputtered Mo and SiO₂ coating with absorption of 5% across the infrared is described experimentally and theoretically.

  5. Absorption of water and lubricating oils into porous nylon

    NASA Technical Reports Server (NTRS)

    Bertrand, P. A.

    1995-01-01

    Oil and water absorption from air into sintered porous nylon can be described by infiltration into the pores of the material. This process can be modeled by a diffusion-like mechanism. For water absorption, we find a formal diffusion coefficient of 1.5 x 10(exp -4)sq cm/min when the nylon is initially dry. The diffusion coefficient is 4 x 10(exp -6)sq cm/min when the nylon is oil-impregnated prior to air exposure. In a 52% RH atmosphere, dry nylon absorbs 3% w/w water, and oil-impregnated nylon absorbs 0.6% w/w water. For oil absorption there are three steps: (1) surface absorption and infiltration into (2) larger and (3) smaller pores. Surface absorption is too fast to be measured in these experiments. The diffusion coefficient for the second step is 6 x 10(exp -4)sq cm/min for SRG-60 oil into dry nylon and 4 x 10(exp -4)sq cm/min for air-equilibrated nylon. The diffusion coefficient for the third step is about 1 x 10(exp -6)sq cm/min for both cases. The total amount of oil absorbed is 31% w/w. The interaction between water and nylon is not as strong as that between water and cotton-phenolic: oil can replace water, and only a small amount of water can enter previously oil-impregnated nylon.

  6. Percutaneous absorption of Octopirox.

    PubMed

    Black, J G; Kamat, V B

    1988-01-01

    containing 1% Octopirox is 29,400, so that the possibility of systemic effects due to absorption through the skin is remote. PMID:3345970

  7. Resonant Absorption of Bessel Beams

    NASA Astrophysics Data System (ADS)

    Fan, J.; Parra, E.; Milchberg, H. M.

    1999-11-01

    We report the first observation of enhanced laser-plasma optical absorption in a subcritical density plasma resulting from spatial resonances, here in the laser breakdown of a gas with a Bessel beam. The enhancement in absorption is directly correlated to enhancements both in confinement of laser radiation to the plasma and in its heating. Under certain conditions, azimuthal asymmetry in the laser beam is essential for efficient gas breakdown. Simulations of this absorption consistently explain the experimental observations. This work is supported by the National Science Foundation (PHY-9515509) and the US Department of Energy (DEF G0297 ER 41039).

  8. Light absorption measurements: new techniques.

    PubMed

    Hänel, G; Busen, R; Hillenbrand, C; Schloss, R

    1982-02-01

    A new radiometer is described which simplifies measurement of the radiation supply of solar wavelengths. Two methods of measuring the radiant energy absorbed by aerosol particles are described: A photometric technique is used for particles collected on filters, and a calorimetric technique is used for in situ measurements. Data collected with the radiometer and the light absorption techniques yield the heating rate of the atmosphere due to light absorption by the particles. Sample measurements show substantial atmospheric temperature increases due to absorption, especially in industrial regions.

  9. Percutaneous nitroglycerin absorption in rats.

    PubMed

    Horhota, S T; Fung, H L

    1979-05-01

    Percutaneous nitroglycerin absorption was studied in shaved rats by monitoring unchanged plasma drug concentrations for up to 4 hr. Drug absorption from the neat liquid state or from an alcoholic solution was considerably poorer than that from a commercial ointment. This observation was unanticipated since the driving force for percutaneous drug absorption was assumed to be drug thermodynamics. Potential artifacts such as drug volatilization from the skin, reduction of surface area through droplet formation, and vehicle occlusion were investigated, but they did not appear to be responsible for the observed results. Two experimental aqueous nitroglycerin gels were prepared with polyethylene glycol 400. One gel contained just sufficient polyethylene glycol to solubilize the nitroglycerin; the other had excess polyethylene glycol to solubilize nitroglycerin far below saturation. Both gels gave extremely low plasma nitroglycerin levels. The composite data suggested that percutaneous nitroglycerin absorption is highly vehicle dependent and that this dependency cannot be explained by simple consideration of drug thermodynamic activity.

  10. Circadian Regulation of Macronutrient Absorption.

    PubMed

    Hussain, M Mahmood; Pan, Xiaoyue

    2015-12-01

    Various intestinal functions exhibit circadian rhythmicity. Disruptions in these rhythms as in shift workers and transcontinental travelers are associated with intestinal discomfort. Circadian rhythms are controlled at the molecular level by core clock and clock-controlled genes. These clock genes are expressed in intestinal cells, suggesting that they might participate in the circadian regulation of intestinal functions. A major function of the intestine is nutrient absorption. Here, we will review absorption of proteins, carbohydrates, and lipids and circadian regulation of various transporters involved in their absorption. A better understanding of circadian regulation of intestinal absorption might help control several metabolic disorders and attenuate intestinal discomfort associated with disruptions in sleep-wake cycles.

  11. Modeling the effects of prior infection on vaccine efficacy

    SciTech Connect

    Smith, D.J.; Forrest, S.; Ackley, D.H.; Perelson, A.S.

    1997-11-01

    We performed computer simulations to study the effects of prior infection on vaccine efficacy. We injected three antigens sequentially. The first antigen, designated the prior, represented a prior infection or vaccination. The second antigen, the vaccine, represented a single component of the trivalent influenza vaccine. The third antigen, the epidemic, represented challenge by an epidemic strain. For a fixed vaccine to epidemic strain cross-reactivities to the vaccine and to the epidemic strains. We found that, for many cross-reactivities, vaccination, when it had been preceded by a prior infection, provided more protection than vaccination alone. However, at some cross-reactivities, the prior infection reduced protection by clearing the vaccine before it had the chance to produce protective memory. The cross-reactivities between the prior, vaccine and epidemic strains played a major role in determining vaccine efficacy. This work has applications to understanding vaccination against viruses such as influenza that are continually mutating.

  12. Cavity-enhanced absorption spectroscopy with a red LED source for NOx trace analysis

    NASA Astrophysics Data System (ADS)

    Triki, M.; Cermak, P.; Méjean, G.; Romanini, D.

    2008-04-01

    Incoherent broad-band cavity-enhanced absorption spectroscopy (IBB-CEAS) based on arc lamps has been around for a few years, but only two reports exist using light-emitting diodes (LEDs). We present a setup based on a 643-nm LED which is of interest for the simultaneous detection of NO3 and NO2. The latter is chosen for testing as it is stable and available in calibrated diluted samples. A detection limit in the ppbv range is obtained with 2-min averaging (5×10-9 /cm rms baseline noise level), comparable to the best performance of chemiluminescence devices used for pollution monitoring. At 1-s acquisition time, the detection limit is below 10 ppbv. Extrapolation to NO3 yields a detection limit of a few pptv for a few minutes averaging. We also test the retrieval of absolute sample absorption (and concentration) using the cavity mirror reflectivity obtained with a commercial spectrophotometer, and we conclude that a calibration based on a reference sample of known concentration is preferable for accurate concentration measurements with IBB-CEAS. Finally, we present a rigorous frequency-domain derivation of cavity transmission as a function of wavelength for a broad-band spectrally smooth source, which complements the time-domain derivation by Fiedler et al. This derivation exposes an issue with multiple transverse mode excitation inherent to this technique, which may result in slightly distorted spectral profiles.

  13. Incomplete intestinal absorption of fructose.

    PubMed

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-08-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children.

  14. Incomplete intestinal absorption of fructose.

    PubMed Central

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-01-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children. PMID:6476870

  15. Bayesian estimation of generalized exponential distribution under noninformative priors

    NASA Astrophysics Data System (ADS)

    Moala, Fernando Antonio; Achcar, Jorge Alberto; Tomazella, Vera Lúcia Damasceno

    2012-10-01

    The generalized exponential distribution, proposed by Gupta and Kundu (1999), is a good alternative to standard lifetime distributions as exponential, Weibull or gamma. Several authors have considered the problem of Bayesian estimation of the parameters of generalized exponential distribution, assuming independent gamma priors and other informative priors. In this paper, we consider a Bayesian analysis of the generalized exponential distribution by assuming the conventional noninformative prior distributions, as Jeffreys and reference prior, to estimate the parameters. These priors are compared with independent gamma priors for both parameters. The comparison is carried out by examining the frequentist coverage probabilities of Bayesian credible intervals. We shown that maximal data information prior implies in an improper posterior distribution for the parameters of a generalized exponential distribution. It is also shown that the choice of a parameter of interest is very important for the reference prior. The different choices lead to different reference priors in this case. Numerical inference is illustrated for the parameters by considering data set of different sizes and using MCMC (Markov Chain Monte Carlo) methods.

  16. Prior Learning Assessment in Canada: A Credit to Workforce Development.

    ERIC Educational Resources Information Center

    Burke, Roberta; Van Kleef, Joy

    1997-01-01

    Describes the implementation of Prior Learning Assessment (PLA) at many educational institutions across Canada. Suggests that PLA should be incorporated into every skills training and upgrading program. (JOW)

  17. Prior knowledge in recalling arguments in bioethical dilemmas

    PubMed Central

    Schmidt, Hiemke K.; Rothgangel, Martin; Grube, Dietmar

    2015-01-01

    Prior knowledge is known to facilitate learning new information. Normally in studies confirming this outcome the relationship between prior knowledge and the topic to be learned is obvious: the information to be acquired is part of the domain or topic to which the prior knowledge belongs. This raises the question as to whether prior knowledge of various domains facilitates recalling information. In this study 79 eleventh-grade students completed a questionnaire on their prior knowledge of seven different domains related to the bioethical dilemma of prenatal diagnostics. The students read a text containing arguments for and arguments against prenatal diagnostics. After 1 week and again 12 weeks later they were asked to write down all the arguments they remembered. Prior knowledge helped them recall the arguments 1 week (r = 0.350) and 12 weeks (r = 0.316) later. Prior knowledge of three of the seven domains significantly helped them recall the arguments 1 week later (correlations between r = 0.194 and 0.394). Partial correlations with interest as a control item revealed that interest did not explain the relationship between prior knowledge and recall. Prior knowledge of different domains jointly supports the recall of arguments related to bioethical topics. PMID:26441702

  18. Electromagnetic machines in cancer treatment: The "Priore affair".

    PubMed

    Karamanou, Marianna; Papaioannou, Theodore G; Tsoucalas, Gregory; Laios, Konstantinos; Androutsos, George

    2015-01-01

    In the 1960s and 1970s the Italian born scientist Antonio Priore, working in France, amazed the public and divided the scientific world with his invention, a machine which could cure a variety of illnesses, including cancer. Gaining the support of the French government and several scientific organizations, Priore received a great amount of money in funds to sustain his research. Without exposing his exact method, the scientific world questioned the legitimacy of Priore's research. For almost two decades scientists, institutes, journalists and cancer patients were implicated in a sensational case, known as the "Priore affair".

  19. Experimental determination of single CdSe nanowire absorption cross sections through photothermal imaging.

    PubMed

    Giblin, Jay; Syed, Muhammad; Banning, Michael T; Kuno, Masaru; Hartland, Greg

    2010-01-26

    Absorption cross sections ((sigma)abs) of single branched CdSe nanowires (NWs) have been measured by photothermal heterodyne imaging (PHI). Specifically, PHI signals from isolated gold nanoparticles (NPs) with known cross sections were compared to those of individual CdSe NWs excited at 532 nm. This allowed us to determine average NW absorption cross sections at 532 nm of (sigma)abs = (3.17 +/- 0.44) x 10(-11) cm2/microm (standard error reported). This agrees well with a theoretical value obtained using a classical electromagnetic analysis ((sigma)abs = 5.00 x 10(-11) cm2/microm) and also with prior ensemble estimates. Furthermore, NWs exhibit significant absorption polarization sensitivities consistent with prior NW excitation polarization anisotropy measurements. This has enabled additional estimates of the absorption cross section parallel ((sigma)abs) and perpendicular ((sigma)abs(perpendicular) to the NW growth axis, as well as the corresponding NW absorption anisotropy ((rho)abs). Resulting values of (sigma)abs = (5.6 +/- 1.1) x 10(-11) cm2/microm, (sigma)abs(perpendicular) = (1.26 +/- 0.21) x 10(-11) cm2/microm, and (rho)abs = 0.63+/- 0.04 (standard errors reported) are again in good agreement with theoretical predictions. These measurements all indicate sizable NW absorption cross sections and ultimately suggest the possibility of future direct single NW absorption studies.

  20. Simple and Versatile Turbidimetric Monitoring of Bacterial Growth in Liquid Cultures Using a Customized 3D Printed Culture Tube Holder and a Miniaturized Spectrophotometer: Application to Facultative and Strictly Anaerobic Bacteria

    PubMed Central

    Maia, Margarida R. G.; Marques, Sara; Cabrita, Ana R. J.; Wallace, R. John; Thompson, Gertrude; Fonseca, António J. M.; Oliveira, Hugo M.

    2016-01-01

    Here we introduce a novel strategy for turbidimetric monitoring of bacterial growth in liquid culture. The instrumentation comprises a light source, a customized 3D printed culture tube holder and a miniaturized spectrophotometer, connected through optical cables. Due to its small footprint and the possibility to operate with external light, bacterial growth was directly monitored from culture tubes in a simple and versatile fashion. This new portable measurement technique was used to monitor the growth of facultative (Escherichia coli ATCC/25922, and Staphylococcus aureus ATCC/29213) and strictly (Butyrivibrio fibrisolvens JW11, Butyrivibrio proteoclasticus P18, and Propionibacterium acnes DSMZ 1897) anaerobic bacteria. For E. coli and S. aureus, the growth rates calculated from normalized optical density values were compared with those ones obtained using a benchtop spectrophotometer without significant differences (P = 0.256). For the strictly anaerobic species, a high precision (relative standard deviation < 3.5%) was observed between replicates up to 48 h. Regarding its potential for customization, this manifold could accommodate further developments for customized turbidimetric monitoring, such as the use of light-emitting diodes as a light source or flow cells.

  1. Simple and Versatile Turbidimetric Monitoring of Bacterial Growth in Liquid Cultures Using a Customized 3D Printed Culture Tube Holder and a Miniaturized Spectrophotometer: Application to Facultative and Strictly Anaerobic Bacteria.

    PubMed

    Maia, Margarida R G; Marques, Sara; Cabrita, Ana R J; Wallace, R John; Thompson, Gertrude; Fonseca, António J M; Oliveira, Hugo M

    2016-01-01

    Here we introduce a novel strategy for turbidimetric monitoring of bacterial growth in liquid culture. The instrumentation comprises a light source, a customized 3D printed culture tube holder and a miniaturized spectrophotometer, connected through optical cables. Due to its small footprint and the possibility to operate with external light, bacterial growth was directly monitored from culture tubes in a simple and versatile fashion. This new portable measurement technique was used to monitor the growth of facultative (Escherichia coli ATCC/25922, and Staphylococcus aureus ATCC/29213) and strictly (Butyrivibrio fibrisolvens JW11, Butyrivibrio proteoclasticus P18, and Propionibacterium acnes DSMZ 1897) anaerobic bacteria. For E. coli and S. aureus, the growth rates calculated from normalized optical density values were compared with those ones obtained using a benchtop spectrophotometer without significant differences (P = 0.256). For the strictly anaerobic species, a high precision (relative standard deviation < 3.5%) was observed between replicates up to 48 h. Regarding its potential for customization, this manifold could accommodate further developments for customized turbidimetric monitoring, such as the use of light-emitting diodes as a light source or flow cells.

  2. Simple and Versatile Turbidimetric Monitoring of Bacterial Growth in Liquid Cultures Using a Customized 3D Printed Culture Tube Holder and a Miniaturized Spectrophotometer: Application to Facultative and Strictly Anaerobic Bacteria.

    PubMed

    Maia, Margarida R G; Marques, Sara; Cabrita, Ana R J; Wallace, R John; Thompson, Gertrude; Fonseca, António J M; Oliveira, Hugo M

    2016-01-01

    Here we introduce a novel strategy for turbidimetric monitoring of bacterial growth in liquid culture. The instrumentation comprises a light source, a customized 3D printed culture tube holder and a miniaturized spectrophotometer, connected through optical cables. Due to its small footprint and the possibility to operate with external light, bacterial growth was directly monitored from culture tubes in a simple and versatile fashion. This new portable measurement technique was used to monitor the growth of facultative (Escherichia coli ATCC/25922, and Staphylococcus aureus ATCC/29213) and strictly (Butyrivibrio fibrisolvens JW11, Butyrivibrio proteoclasticus P18, and Propionibacterium acnes DSMZ 1897) anaerobic bacteria. For E. coli and S. aureus, the growth rates calculated from normalized optical density values were compared with those ones obtained using a benchtop spectrophotometer without significant differences (P = 0.256). For the strictly anaerobic species, a high precision (relative standard deviation < 3.5%) was observed between replicates up to 48 h. Regarding its potential for customization, this manifold could accommodate further developments for customized turbidimetric monitoring, such as the use of light-emitting diodes as a light source or flow cells. PMID:27630632

  3. Simple and Versatile Turbidimetric Monitoring of Bacterial Growth in Liquid Cultures Using a Customized 3D Printed Culture Tube Holder and a Miniaturized Spectrophotometer: Application to Facultative and Strictly Anaerobic Bacteria

    PubMed Central

    Maia, Margarida R. G.; Marques, Sara; Cabrita, Ana R. J.; Wallace, R. John; Thompson, Gertrude; Fonseca, António J. M.; Oliveira, Hugo M.

    2016-01-01

    Here we introduce a novel strategy for turbidimetric monitoring of bacterial growth in liquid culture. The instrumentation comprises a light source, a customized 3D printed culture tube holder and a miniaturized spectrophotometer, connected through optical cables. Due to its small footprint and the possibility to operate with external light, bacterial growth was directly monitored from culture tubes in a simple and versatile fashion. This new portable measurement technique was used to monitor the growth of facultative (Escherichia coli ATCC/25922, and Staphylococcus aureus ATCC/29213) and strictly (Butyrivibrio fibrisolvens JW11, Butyrivibrio proteoclasticus P18, and Propionibacterium acnes DSMZ 1897) anaerobic bacteria. For E. coli and S. aureus, the growth rates calculated from normalized optical density values were compared with those ones obtained using a benchtop spectrophotometer without significant differences (P = 0.256). For the strictly anaerobic species, a high precision (relative standard deviation < 3.5%) was observed between replicates up to 48 h. Regarding its potential for customization, this manifold could accommodate further developments for customized turbidimetric monitoring, such as the use of light-emitting diodes as a light source or flow cells. PMID:27630632

  4. Modulation of ganciclovir intestinal absorption in presence of absorption enhancers.

    PubMed

    Shah, Pranav; Jogani, Viral; Mishra, Pushpa; Mishra, Anil Kumar; Bagchi, Tamishraha; Misra, Ambikanandan

    2007-10-01

    The purpose of this investigation was to study the influences of absorption enhancers in increasing oral bioavailability of Ganciclovir (GAN) by assessing the transepithelial permeation across cell monolayers in vitro and bioavailability in rats in vivo. The permeation of GAN across Caco-2 and MDCK cell monolayers in the absence/presence of dimethyl-beta-cyclodextrin (DMbetaCD), chitosan hydrochloride (CH), sodium lauryl sulphate (SLS), and their combinations was studied for a 2-h period. GAN was administered to rats in absence/presence of absorption enhancers and drug contents in plasma were estimated. We found that the apparent permeability coefficient (Papp) of GAN in absence of absorption enhancers (control) were 0.261 +/- 0.072 x 10(-6) and 0.486 +/- 0.063 x 10(-6) cm/s in Caco-2 and MDCK cell monolayers, respectively, whereas in the presence of DMbetaCD, CH, SLS, and their combinations, Papp of GAN increased by 5- to 25-fold and 7- to 33-fold as compared to control in Caco-2 and MDCK cell monolayers, respectively. However, in rats, the maximum enhancement in bioavailability of GAN during coadministration of these absorption enhancers was only fivefold compared to GAN control. To conclude, the absorption enhancers-DMbetaCD, CH, SLS, and their combinations demonstrated significant improvement in transepithelial permeation and bioavailability of GAN.

  5. Converting Sabine absorption coefficients to random incidence absorption coefficients.

    PubMed

    Jeong, Cheol-Ho

    2013-06-01

    Absorption coefficients measured by the chamber method are referred to as Sabine absorption coefficients, which sometimes exceed unity due to the finite size of a sample and non-uniform intensity in the reverberation chambers under test. In this study, conversion methods from Sabine absorption coefficients to random incidence absorption coefficients are proposed. The overestimations of the Sabine absorption coefficient are investigated theoretically based on Miki's model for porous absorbers backed by a rigid wall or an air cavity, resulting in conversion factors. Additionally, three optimizations are suggested: An optimization method for the surface impedances for locally reacting absorbers, the flow resistivity for extendedly reacting absorbers, and the flow resistance for fabrics. With four porous type absorbers, the conversion methods are validated. For absorbers backed by a rigid wall, the surface impedance optimization produces the best results, while the flow resistivity optimization also yields reasonable results. The flow resistivity and flow resistance optimization for extendedly reacting absorbers are also found to be successful. However, the theoretical conversion factors based on Miki's model do not guarantee reliable estimations, particularly at frequencies below 250 Hz and beyond 2500 Hz.

  6. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption.

  7. Biosorption of platinum and palladium for their separation/preconcentration prior to graphite furnace atomic absorption spectrometric determination

    NASA Astrophysics Data System (ADS)

    Godlewska-Żyłkiewicz, Beata

    2003-08-01

    Inexpensive baker's yeast Saccharomyces cerevisiae and green algae Chlorella vulgaris, either free or immobilized on silica gel have been shown to selectively accumulate platinum and palladium from water samples in acidic medium (pH 1.6-1.8). Optimization of conditions of metals biosorption (sample pH, algae and yeast masses, adsorption time, temperature) was performed in batch mode. The procedure of matrix separation based on biosorption of platinum and palladium on algae C. vulgaris covalently immobilized on silica gel in flow mode was developed. The use of algae in flow procedure offers several advantages compared with its use in the batch mode. The procedure shows better reproducibility (<2%), improved efficiency of platinum retention on the column (93.3±1.6%), is less laborious and less time consuming. The best recovery of biosorbed metals from column (87.7±3.3% for platinum and 96.8±1.1 for palladium) was obtained with solution of 0.3 mol l -1 thiourea in 1 mol l -1 hydrochloric acid. The influence of thiourea on analytical signals of examined metals during GFAAS determination is discussed. The procedure has been applied for separation of noble metals from tap and waste water samples spiked with platinum and palladium.

  8. 10 CFR 20.2104 - Determination of prior occupational dose.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Determination of prior occupational dose. 20.2104 Section....2104 Determination of prior occupational dose. (a) For each individual who is likely to receive an annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine...

  9. High School Students' Publication Rights and Prior Restraint.

    ERIC Educational Resources Information Center

    Huffman, John L.; Trauth, Denise M.

    1981-01-01

    Federal court decisions on high school students' publication rights in the Second, Fourth, Fifth, and Seventh Circuits reveal substantial disagreement about school officials' power of prior restraint over student publications. The courts' opinions range from approval of broad powers of prior restraint to denial of any power. (Author/RW)

  10. 18 CFR 415.51 - Prior non-conforming structures.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Prior non-conforming structures. 415.51 Section 415.51 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-FLOOD PLAIN REGULATIONS Enforcement § 415.51 Prior...

  11. 18 CFR 415.51 - Prior non-conforming structures.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Prior non-conforming structures. 415.51 Section 415.51 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-FLOOD PLAIN REGULATIONS Enforcement § 415.51 Prior...

  12. 18 CFR 415.51 - Prior non-conforming structures.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 2 2014-04-01 2014-04-01 false Prior non-conforming structures. 415.51 Section 415.51 Conservation of Power and Water Resources DELAWARE RIVER BASIN COMMISSION ADMINISTRATIVE MANUAL BASIN REGULATIONS-FLOOD PLAIN REGULATIONS Enforcement § 415.51 Prior...

  13. 5 CFR 7201.103 - Prior approval for outside employment.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE EQUAL EMPLOYMENT OPPORTUNITY COMMISSION § 7201.103 Prior... or her Deputy Ethics Counselor or designee. (b) In addition to approval under paragraph (a) of this section, an employee must obtain prior written approval from the Designated Agency Ethics Official...

  14. Nudging toward Inquiry: Awakening and Building upon Prior Knowledge

    ERIC Educational Resources Information Center

    Fontichiaro, Kristin, Comp.

    2010-01-01

    "Prior knowledge" (sometimes called schema or background knowledge) is information one already knows that helps him/her make sense of new information. New learning builds on existing prior knowledge. In traditional reporting-style research projects, students bypass this crucial step and plow right into answer-finding. It's no wonder that many…

  15. Explanation and Prior Knowledge Interact to Guide Learning

    ERIC Educational Resources Information Center

    Williams, Joseph J.; Lombrozo, Tania

    2013-01-01

    How do explaining and prior knowledge contribute to learning? Four experiments explored the relationship between explanation and prior knowledge in category learning. The experiments independently manipulated whether participants were prompted to explain the category membership of study observations and whether category labels were informative in…

  16. 10 CFR 20.2104 - Determination of prior occupational dose.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Determination of prior occupational dose. 20.2104 Section....2104 Determination of prior occupational dose. (a) For each individual who is likely to receive an annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine...

  17. 10 CFR 20.2104 - Determination of prior occupational dose.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Determination of prior occupational dose. 20.2104 Section....2104 Determination of prior occupational dose. (a) For each individual who is likely to receive an annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine...

  18. 10 CFR 20.2104 - Determination of prior occupational dose.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Determination of prior occupational dose. 20.2104 Section....2104 Determination of prior occupational dose. (a) For each individual who is likely to receive an annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine...

  19. 10 CFR 20.2104 - Determination of prior occupational dose.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Determination of prior occupational dose. 20.2104 Section....2104 Determination of prior occupational dose. (a) For each individual who is likely to receive an annual occupational dose requiring monitoring under § 20.1502, the licensee shall determine...

  20. Effects of Prior Knowledge on Memory: Implications for Education

    ERIC Educational Resources Information Center

    Shing, Yee Lee; Brod, Garvin

    2016-01-01

    The encoding, consolidation, and retrieval of events and facts form the basis for acquiring new skills and knowledge. Prior knowledge can enhance those memory processes considerably and thus foster knowledge acquisition. But prior knowledge can also hinder knowledge acquisition, in particular when the to-be-learned information is inconsistent with…

  1. 12 CFR 303.82 - Transactions requiring prior notice.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... company requiring prior notice to the FDIC, if, immediately after the transaction, the acquiring person..., shall give the FDIC 60 days prior written notice, as specified in § 303.84, before acquiring control of an insured state nonmember bank or any parent company, unless the acquisition is exempt under §...

  2. Tools for investigating the prior distribution in Bayesian hydrology

    NASA Astrophysics Data System (ADS)

    Tang, Yating; Marshall, Lucy; Sharma, Ashish; Smith, Tyler

    2016-07-01

    Bayesian inference is one of the most popular tools for uncertainty analysis in hydrological modeling. While much emphasis has been placed on the selection of appropriate likelihood functions within Bayesian hydrology, few researchers have evaluated the importance of the prior distribution in deriving appropriate posterior distributions. This paper describes tools for the evaluation of parameter sensitivity to the prior distribution to provide guidelines for defining meaningful priors. The tools described here consist of two measurements, the Kullback-Leibler Divergence (KLD) and the prior information elasticity. The Kullback-Leibler Divergence (KLD) is applied to calculate differences between the prior and posterior distributions for different cases. The prior information elasticity is then used to quantify the responsiveness of the KLD values to the change of prior distributions and length of available data. The tools are demonstrated via a Bayesian framework using an MCMC algorithm for a conceptual hydrologic model with both synthetic and real cases. The results of the application of this toolkit suggest the prior distribution can have a significant impact on the posterior distribution and should be more routinely assessed in hydrologic studies.

  3. 1 CFR 10.13 - Coverage of prior years.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 1 General Provisions 1 2014-01-01 2012-01-01 true Coverage of prior years. 10.13 Section 10.13... REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.13 Coverage of prior years. The Administrative Committee may authorize the publication of volumes of papers of the Presidents covering specified...

  4. 1 CFR 10.13 - Coverage of prior years.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 1 General Provisions 1 2012-01-01 2012-01-01 false Coverage of prior years. 10.13 Section 10.13... REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.13 Coverage of prior years. The Administrative Committee may authorize the publication of volumes of papers of the Presidents covering specified...

  5. 1 CFR 10.13 - Coverage of prior years.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 1 General Provisions 1 2013-01-01 2012-01-01 true Coverage of prior years. 10.13 Section 10.13... REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.13 Coverage of prior years. The Administrative Committee may authorize the publication of volumes of papers of the Presidents covering specified...

  6. Prior-List Intrusions in Serial Recall Are Positional

    ERIC Educational Resources Information Center

    Osth, Adam F.; Dennis, Simon

    2015-01-01

    Henson (1996) provided a number of demonstrations of error patterns in serial recall that contradict chaining models. One such error pattern concerned when participants make intrusions from prior lists: Rather than originating from random positions in the prior list, intrusions tend to be recalled in the same position as their position in the…

  7. Portfolios for Prior Learning Assessment: Caught between Diversity and Standardization

    ERIC Educational Resources Information Center

    Sweygers, Annelies; Soetewey, Kim; Meeus, Wil; Struyf, Elke; Pieters, Bert

    2009-01-01

    In recent years, procedures have been established in Flanders for "Prior Learning Assessment" (PLA) outside the formal learning circuit, of which the portfolio is a regular component. In order to maximize the possibilities of acknowledgement of prior learning assessment, the Flemish government is looking for a set of common criteria and principles…

  8. 16 CFR 453.5 - Services provided without prior approval.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Services provided without prior approval. 453.5 Section 453.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES FUNERAL INDUSTRY PRACTICES § 453.5 Services provided without prior approval. (a) Unfair or deceptive acts...

  9. 16 CFR 453.5 - Services provided without prior approval.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 1 2011-01-01 2011-01-01 false Services provided without prior approval. 453.5 Section 453.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES FUNERAL INDUSTRY PRACTICES § 453.5 Services provided without prior approval. (a) Unfair or deceptive acts...

  10. 16 CFR 453.5 - Services provided without prior approval.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 1 2012-01-01 2012-01-01 false Services provided without prior approval. 453.5 Section 453.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES FUNERAL INDUSTRY PRACTICES § 453.5 Services provided without prior approval. (a) Unfair or deceptive acts...

  11. 16 CFR 453.5 - Services provided without prior approval.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Services provided without prior approval. 453.5 Section 453.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES FUNERAL INDUSTRY PRACTICES § 453.5 Services provided without prior approval. (a) Unfair or deceptive acts...

  12. 16 CFR 453.5 - Services provided without prior approval.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Services provided without prior approval. 453.5 Section 453.5 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES FUNERAL INDUSTRY PRACTICES § 453.5 Services provided without prior approval. (a) Unfair or deceptive acts...

  13. Drunkorexia: Calorie Restriction Prior to Alcohol Consumption among College Freshman

    ERIC Educational Resources Information Center

    Burke, Sloane C.; Cremeens, Jennifer; Vail-Smith, Karen; Woolsey, Conrad

    2010-01-01

    Using a sample of 692 freshmen at a southeastern university, this study examined caloric restriction among students prior to planned alcohol consumption. Participants were surveyed for self-reported alcohol consumption, binge drinking, and caloric intake habits prior to drinking episodes. Results indicated that 99 of 695 (14%) of first year…

  14. 28. VIEW OF WHITE SAGE PRIOR TO BEING PAINTED COAST ...

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

    28. VIEW OF WHITE SAGE PRIOR TO BEING PAINTED COAST GUARD COLORS OF BLACK AND WHITE. NOTE ALSO THE PHOTOGRAPH WAS TAKEN PRIOR TO THE INSTALLATION OF A-FRAME MAST AND BOOM AND TO THE CONSTRUCTION OF TURTLE DECK. - U.S. Coast Guard Cutter WHITE SAGE, U.S. Coast Guard 1st District Base, 1 Thames Street, Bristol, Bristol County, RI

  15. 7 CFR 1412.74 - Prior enrollment in DCP.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Prior enrollment in DCP. 1412.74 Section 1412.74... (ACRE) Program § 1412.74 Prior enrollment in DCP. (a) If a farm was enrolled in a DCP contract according... request to have the DCP contract withdrawn for that crop year. To participate in an annual ACRE...

  16. 18 CFR 415.51 - Prior non-conforming structures.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Prior non-conforming... ADMINISTRATIVE MANUAL BASIN REGULATIONS-FLOOD PLAIN REGULATIONS Enforcement § 415.51 Prior non-conforming... this part): (a) A non-conforming structure in the floodway may not be expanded, except that it may...

  17. 45 CFR 670.6 - Prior possession exception.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Prior possession exception. 670.6 Section 670.6 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION CONSERVATION OF ANTARCTIC ANIMALS AND PLANTS Prohibited Acts, Exceptions § 670.6 Prior possession exception....

  18. 7 CFR 4280.194 - Actions prior to grant closing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Program General Energy Audit and Renewable Energy Development Assistance Grants § 4280.194 Actions prior to grant closing. Applicants expecting funds from other sources for use in completing projects being partially financed with Agency funds must have these funds from other such sources prior to grant...

  19. 7 CFR 4280.194 - Actions prior to grant closing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Program General Energy Audit and Renewable Energy Development Assistance Grants § 4280.194 Actions prior to grant closing. Applicants expecting funds from other sources for use in completing projects being partially financed with Agency funds must have these funds from other such sources prior to grant...

  20. 50 CFR 12.32 - Effect of prior illegality.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 12.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... prior illegality. The effect of any prior illegality on a subsequent holder of any wildlife or plant..., restrictions, conditions, or requirements which apply to a particular species of wildlife or plant under...

  1. 50 CFR 12.32 - Effect of prior illegality.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 12.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... prior illegality. The effect of any prior illegality on a subsequent holder of any wildlife or plant..., restrictions, conditions, or requirements which apply to a particular species of wildlife or plant under...

  2. 50 CFR 12.32 - Effect of prior illegality.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 12.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... prior illegality. The effect of any prior illegality on a subsequent holder of any wildlife or plant..., restrictions, conditions, or requirements which apply to a particular species of wildlife or plant under...

  3. 50 CFR 12.32 - Effect of prior illegality.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 12.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... prior illegality. The effect of any prior illegality on a subsequent holder of any wildlife or plant..., restrictions, conditions, or requirements which apply to a particular species of wildlife or plant under...

  4. 32 CFR 644.117 - Procedure prior to trial.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Procedure prior to trial. 644.117 Section 644.117 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Acquisition Acquisition by Condemnation Proceedings § 644.117 Procedure prior to...

  5. 34 CFR 303.403 - Prior notice; native language.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 2 2011-07-01 2010-07-01 true Prior notice; native language. 303.403 Section 303.403... TODDLERS WITH DISABILITIES Procedural Safeguards General § 303.403 Prior notice; native language. (a... file a complaint and the timelines under those procedures. (c) Native language. (1) The notice must...

  6. 7 CFR 1412.74 - Prior enrollment in DCP.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Prior enrollment in DCP. 1412.74 Section 1412.74... (ACRE) Program § 1412.74 Prior enrollment in DCP. (a) If a farm was enrolled in a DCP contract according... request to have the DCP contract withdrawn for that crop year. To participate in an annual ACRE...

  7. 7 CFR 1412.74 - Prior enrollment in DCP.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Prior enrollment in DCP. 1412.74 Section 1412.74... (ACRE) Program § 1412.74 Prior enrollment in DCP. (a) If a farm was enrolled in a DCP contract according... request to have the DCP contract withdrawn for that crop year. To participate in an annual ACRE...

  8. 7 CFR 1412.74 - Prior enrollment in DCP.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Prior enrollment in DCP. 1412.74 Section 1412.74... (ACRE) Program § 1412.74 Prior enrollment in DCP. (a) If a farm was enrolled in a DCP contract according... request to have the DCP contract withdrawn for that crop year. To participate in an annual ACRE...

  9. 7 CFR 1412.74 - Prior enrollment in DCP.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Prior enrollment in DCP. 1412.74 Section 1412.74... (ACRE) Program § 1412.74 Prior enrollment in DCP. (a) If a farm was enrolled in a DCP contract according... request to have the DCP contract withdrawn for that crop year. To participate in an annual ACRE...

  10. 40 CFR 266.101 - Management prior to burning.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Management prior to burning. 266.101... MANAGEMENT FACILITIES Hazardous Waste Burned in Boilers and Industrial Furnaces § 266.101 Management prior to burning. (a) Generators. Generators of hazardous waste that is burned in a boiler or industrial...

  11. 1 CFR 10.13 - Coverage of prior years.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 1 General Provisions 1 2010-01-01 2010-01-01 false Coverage of prior years. 10.13 Section 10.13 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.13 Coverage of prior years. The...

  12. 1 CFR 10.13 - Coverage of prior years.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 1 General Provisions 1 2011-01-01 2011-01-01 false Coverage of prior years. 10.13 Section 10.13 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER PRESIDENTIAL PAPERS Annual Publication § 10.13 Coverage of prior years. The...

  13. Sound absorption in metallic foams

    NASA Astrophysics Data System (ADS)

    Lu, T. J.; Hess, Audrey; Ashby, M. F.

    1999-06-01

    The sound absorption capacity of one type of aluminum alloy foams—trade name Alporas—is studied experimentally. The foam in its as-received cast form contains closed porosities, and hence does not absorb sound well. To make the foam more transparent to air motion, techniques based on either rolling or hole drilling are used. Under rolling, the faces of some of the cells break to form small sharp-edged cracks as observed from a scanning electronic microscope. These cracks become passage ways for the in-and-out movement of air particles, resulting in sound absorption improvement. The best performance is nevertheless achieved via hole drilling where nearly all of the sound can be absorbed at selected frequencies. Combining rolling with hole drilling does not appear to lend additional benefits for sound absorption. Image analysis is carried out to characterize the changes in cell morphologies due to rolling/compression, and the drop in elastic modulus due to the formation of cracks is recorded. The effects of varying the relative foam density and panel thickness on sound absorption are measured, and optimal relative density and thickness of the panel are identified. Analytical models are used to explain the measured increase in sound absorption due to rolling and/or drilling. Sound absorbed by viscous flow across small cracks appears to dominate over that dissipated via other mechanisms.

  14. Molar Absorptivity and Concentration-Dependent Quantum Yield of Fe(II) Photo-Formation for the Aqueous Solutions of Fe(III)-Dicarboxylate Complexes

    NASA Astrophysics Data System (ADS)

    Hitomi, Y.; Arakaki, T.

    2009-12-01

    Redox cycles of iron in the aquatic environment affect formation of reactive oxygen species such as hydrogen peroxide and hydroxyl radicals, which in turn determines lifetimes of many organic compounds. Although aqueous Fe(III)-dicarboxylate complexes are considered to be important sources of photo-formed Fe(II), molar absorptivity and quantum yield of Fe(II) formation for individual species are not well understood. We initiated a study to characterize Fe(II) photo-formation from Fe(III)-dicarboxylates with the concentration ranges that are relevant to the natural aquatic environment. The Visual MINTEQ computer program was used to calculate the equilibrium concentrations of individual Fe(III)-dicarboxylate species. The molar absorptivity of Fe(III)-dicarboxylate species was obtained by UV-VIS spectrophotometer, and the product of the quantum yield and the molar absorptivity of Fe(III)-dicarboxylate species were obtained from photochemical experiments. These experimental data were combined with the calculated equilibrium Fe(III)-dicarboxylate concentrations to determine individual molar absorptivity and quantum yield of Fe(II) photo-formation for a specific Fe(III)-dicarboxylate species. We used initial concentrations of less than 10 micromolar Fe(III) to study the photochemical formation of Fe(II). Dicarboxylate compounds studied include oxalate, malonate, succinate, malate, and phthalate. We report molar absorptivity and concentration-dependent quantum yields of Fe(II) photo-formation of individual Fe(III)-dicarboxylates.

  15. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    PubMed

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-04-28

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression.

  16. How Prior Knowledge Affects Word Identification and Comprehension

    PubMed Central

    Priebe, Sarah J.; Keenan, Janice M.; Miller, Amanda C.

    2011-01-01

    While prior knowledge of a passage topic is known to facilitate comprehension, little is known about how it affects word identification. We examined oral reading errors in good and poor readers when reading a passage where they either had prior knowledge of the passage topic or did not. Children who had prior knowledge of the topic were matched on decoding skill to children who did not know the topic so that the groups differed only on knowledge of the passage topic. Prior knowledge of the passage topic was found to significantly increase fluency and reduce reading errors, especially errors based on graphic information, in poor readers. Two possible mechanisms of how prior knowledge might operate to facilitate word identification were evaluated using the pattern of error types, as was the relationship of errors to comprehension. Implications of knowledge effects for assessment and educational policy are discussed. PMID:21799586

  17. Restricted Covariance Priors with Applications in Spatial Statistics

    PubMed Central

    Smith, Theresa R.; Wakefield, Jon; Dobra, Adrian

    2015-01-01

    We present a Bayesian model for area-level count data that uses Gaussian random effects with a novel type of G-Wishart prior on the inverse variance– covariance matrix. Specifically, we introduce a new distribution called the truncated G-Wishart distribution that has support over precision matrices that lead to positive associations between the random effects of neighboring regions while preserving conditional independence of non-neighboring regions. We describe Markov chain Monte Carlo sampling algorithms for the truncated G-Wishart prior in a disease mapping context and compare our results to Bayesian hierarchical models based on intrinsic autoregression priors. A simulation study illustrates that using the truncated G-Wishart prior improves over the intrinsic autoregressive priors when there are discontinuities in the disease risk surface. The new model is applied to an analysis of cancer incidence data in Washington State. PMID:26753014

  18. Model predicting impact of complexation with cyclodextrins on oral absorption.

    PubMed

    Gamsiz, Ece D; Thombre, Avinash G; Ahmed, Imran; Carrier, Rebecca L

    2013-09-01

    Significant effort and resource expenditure is dedicated to enabling low-solubility oral drug delivery using solubilization technologies. Cyclodextrins (CD) are cyclic oligosaccharides which form inclusion complexes with many drugs and are often used as solubilizing agents. It is not clear prior to developing a drug delivery device with CD what level of absorption enhancement might be achieved; modeling can provide useful guidance in formulation and minimize resource intensive iterative formulation development. A model was developed to enable quantitative, dynamic prediction of the influence of CD on oral absorption of low solubility drug administered as a pre-formed complex. The predominant effects of CD considered were enhancement of dissolution and slowing of precipitation kinetics, as well as binding of free drug in solution. Simulation results with different parameter values reflective of typical drug and CD properties indicate a potential positive (up to five times increase in drug absorption), negative (up to 50% decrease in absorption) or lack of effect of CD. Comparison of model predictions with in vitro and in vivo experimental results indicate that a systems-based dynamic model incorporating CD complexation and key process kinetics may enable quantitative prediction of impact of CD delivered as a pre-formed complex on drug bioavailability.

  19. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  20. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  1. Diabetic lipohypertrophy delays insulin absorption.

    PubMed

    Young, R J; Hannan, W J; Frier, B M; Steel, J M; Duncan, L J

    1984-01-01

    The effect of lipohypertrophy at injection sites on insulin absorption has been studied in 12 insulin-dependent diabetic patients. The clearance of 125I-insulin from sites with lipohypertrophy was significantly slower than from complementary nonhypertrophied sites (% clearance in 3 h, 43.8 +/- 3.5 +/- SEM) control; 35.3 +/- 3.9 lipohypertrophy, P less than 0.05). The degree of the effect was variable but sufficient in several patients to be of clinical importance. Injection-site lipohypertrophy is another factor that modifies the absorption of subcutaneously injected insulin.

  2. Solar powered absorption air conditioning

    NASA Astrophysics Data System (ADS)

    Vardon, J. M.

    1980-04-01

    Artificial means of providing or removing heat from the building are discussed along with the problem of the appropriate building design and construction for a suitable heat climate inside the building. The use of a lithium bromide-water absorption chiller, powered by a hot water store heated by an array of stationary flat collectors, is analyzed. An iterative method of predicting the cooling output from a LiBr-water absorption refrigeration plant having variable heat input is described and a model allowing investigation of the performance of a solar collector and thermal storage system is developed.

  3. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  4. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  5. Implicit Priors in Galaxy Cluster Mass and Scaling Relation Determinations

    NASA Technical Reports Server (NTRS)

    Mantz, A.; Allen, S. W.

    2011-01-01

    Deriving the total masses of galaxy clusters from observations of the intracluster medium (ICM) generally requires some prior information, in addition to the assumptions of hydrostatic equilibrium and spherical symmetry. Often, this information takes the form of particular parametrized functions used to describe the cluster gas density and temperature profiles. In this paper, we investigate the implicit priors on hydrostatic masses that result from this fully parametric approach, and the implications of such priors for scaling relations formed from those masses. We show that the application of such fully parametric models of the ICM naturally imposes a prior on the slopes of the derived scaling relations, favoring the self-similar model, and argue that this prior may be influential in practice. In contrast, this bias does not exist for techniques which adopt an explicit prior on the form of the mass profile but describe the ICM non-parametrically. Constraints on the slope of the cluster mass-temperature relation in the literature show a separation based the approach employed, with the results from fully parametric ICM modeling clustering nearer the self-similar value. Given that a primary goal of scaling relation analyses is to test the self-similar model, the application of methods subject to strong, implicit priors should be avoided. Alternative methods and best practices are discussed.

  6. Random geometric prior forest for multiclass object segmentation.

    PubMed

    Liu, Xiao; Song, Mingli; Tao, Dacheng; Bu, Jiajun; Chen, Chun

    2015-10-01

    Recent advances in object detection have led to the development of segmentation by detection approaches that integrate top-down geometric priors for multiclass object segmentation. A key yet under-addressed issue in utilizing top-down cues for the problem of multiclass object segmentation by detection is efficiently generating robust and accurate geometric priors. In this paper, we propose a random geometric prior forest scheme to obtain object-adaptive geometric priors efficiently and robustly. In the scheme, a testing object first searches for training neighbors with similar geometries using the random geometric prior forest, and then the geometry of the testing object is reconstructed by linearly combining the geometries of its neighbors. Our scheme enjoys several favorable properties when compared with conventional methods. First, it is robust and very fast because its inference does not suffer from bad initializations, poor local minimums or complex optimization. Second, the figure/ground geometries of training samples are utilized in a multitask manner. Third, our scheme is object-adaptive but does not require the labeling of parts or poselets, and thus, it is quite easy to implement. To demonstrate the effectiveness of the proposed scheme, we integrate the obtained top-down geometric priors with conventional bottom-up color cues in the frame of graph cut. The proposed random geometric prior forest achieves the best segmentation results of all of the methods tested on VOC2010/2012 and is 90 times faster than the current state-of-the-art method. PMID:25974937

  7. Hippocampus segmentation using locally weighted prior based level set

    NASA Astrophysics Data System (ADS)

    Achuthan, Anusha; Rajeswari, Mandava

    2015-12-01

    Segmentation of hippocampus in the brain is one of a major challenge in medical image segmentation due to its' imaging characteristics, with almost similar intensity between another adjacent gray matter structure, such as amygdala. The intensity similarity has causes the hippocampus to have weak or fuzzy boundaries. With this main challenge being demonstrated by hippocampus, a segmentation method that relies on image information alone may not produce accurate segmentation results. Therefore, it is needed an assimilation of prior information such as shape and spatial information into existing segmentation method to produce the expected segmentation. Previous studies has widely integrated prior information into segmentation methods. However, the prior information has been utilized through a global manner integration, and this does not reflect the real scenario during clinical delineation. Therefore, in this paper, a locally integrated prior information into a level set model is presented. This work utilizes a mean shape model to provide automatic initialization for level set evolution, and has been integrated as prior information into the level set model. The local integration of edge based information and prior information has been implemented through an edge weighting map that decides at voxel level which information need to be observed during a level set evolution. The edge weighting map shows which corresponding voxels having sufficient edge information. Experiments shows that the proposed integration of prior information locally into a conventional edge-based level set model, known as geodesic active contour has shown improvement of 9% in averaged Dice coefficient.

  8. Effect of folic acid on zinc absorption

    SciTech Connect

    Wada, L.; Keating, S.; King, J.C.; Stokstad, E.L.R.

    1986-03-05

    The effect of folic acid on zinc uptake was studied in the human and in the rat. The serum zinc response to a 25 mg oral dose or zinc was measured with and without a 10 mg dose of folic acid. Serum zinc levels were measured prior to the oral dose of zinc and at hourly intervals up to 4 hours after the dose. When zinc was given along, the increases in serum zinc from baseline at hours 1, 2, 3 and 4 were 92, 118, 92 and 66 ..mu..g/dl, respectively. When both zinc and folic acid were given, the increases in serum zinc at hours 1, 2, 3 and 4 were 100, 140, 110 and 75 ..mu..g/dl, respectively. When the increases in serum zinc were plotted against time, there was no significant difference between the areas under the two curves. The everted jejunal sac from the rat was used to study the effect of folate on zinc transport using 100 ..mu..M zinc in the mucosal buffer. The addition of folic acid at levels up to 10/sup -3/M had no significant effect on zinc transport to the serosal side solution or on uptake by the intestinal mucosa. This in vivo study with humans and in vitro study with rat intestine does not support a direct adverse effect of folic acid on zinc absorption.

  9. Drug repurposing and the prior art patents of competitors.

    PubMed

    Sternitzke, Christian

    2014-12-01

    Drug repurposing (i.e., finding novel indications for established substances) has received increasing attention in industry recently. One challenge of repositioned drugs is obtaining effective patent protection, especially if the 'novel' indications have already been claimed by competitors within the same drug class. Here, I report the case of patents relating to phosphodiesterase type 5 (PDE5) inhibitors. Patentees of later-filed patents on novel indications (even when they could not observe prior patenting of their direct competitors) filed patents for which patent examiners did not see the prior-filed patents of the competitors as relevant prior art, whereas these follower patent applications often failed because of other reasons.

  10. Multi-frame blind deconvolution using sparse priors

    NASA Astrophysics Data System (ADS)

    Dong, Wende; Feng, Huajun; Xu, Zhihai; Li, Qi

    2012-05-01

    In this paper, we propose a method for multi-frame blind deconvolution. Two sparse priors, i.e., the natural image gradient prior and an l1-norm based prior are used to regularize the latent image and point spread functions (PSFs) respectively. An alternating minimization approach is adopted to solve the resulted optimization problem. We use both gray scale blurred frames from a data set and some colored ones which are captured by a digital camera to verify the robustness of our approach. Experimental results show that the proposed method can accurately reconstruct PSFs with complex structures and the restored images are of high quality.

  11. Concentration-modulated absorption spectroscopy.

    PubMed

    Langley, A J; Beaman, R A; Baran, J; Davies, A N; Jones, W J

    1985-07-01

    Concentration modulation is demonstrated to be a technique capable of markedly extending sensitivity limits in absorption spectroscopy. The gain generated relates in such a manner to sample transmittance that for the first reported time direct spectroscopic concentration measurements become possible. When concentration modulation is used with picosecond lasers, state lifetimes can be determined to a limit of approximately 20 psec.

  12. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  13. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process."

  14. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process." PMID:12285766

  15. Phenoxyethanol absorption by polyvinyl chloride.

    PubMed

    Lee, M G

    1984-12-01

    Phenoxyethanol was found to be absorbed by polyvinyl chloride administration sets during continuous irrigation therapy. Depending upon the conditions of administration up to 20% loss of potency could occur. Absorption of the drug by the rigid plastic luer-lock fitting of the set caused softening and decreased rigidity of the plastic.

  16. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  17. Distinct difference in absorption pattern in pigs of betaine provided as a supplement or present naturally in cereal dietary fiber.

    PubMed

    Hedemann, Mette Skou; Theil, Peter Kappel; Lærke, Helle Nygaard; Bach Knudsen, Knud Erik

    2015-03-18

    The net absorption of betaine and choline was determined for 4 h after the first meal of the day in three experiments with porto-arterial catheterized pigs in which betaine was added as a supplement to a low-betaine diet (n=4 pigs) and compared to the net absorption of betaine and choline from high-fiber breads differing in amount and source of dietary fiber (two experiments, n=6 pigs each). Plasma betaine peaked after 30 min when betaine was fed as a supplement, whereas it peaked after 120-180 min when high-fiber breads were fed. Plasma betaine showed no diet×time interaction after feeding with high-fiber breads, indicating that the absorption kinetic did not differ between fiber sources. The net absorption of choline was not affected by the experimental diets. In conclusion, betaine in cereal sources has to be liberated from the matrix prior to absorption, causing delayed absorption.

  18. A Comparison of the First Solar EUV Irradiance Measurements from the SDO/EVE EUV Spectrophotometer (ESP) with the SOHO/CELIAS Solar EUV Monitor (SEM) Absolute Solar EUV Irradiance

    NASA Astrophysics Data System (ADS)

    Didkovsky, Leonid; Judge, Darrell; Wieman, Seth; Woods, Thomas; Eparvier, Francis; Jones, Andrew

    First light measurements from the SDO/EVE EUV Spectrophotometer (ESP) are calibrated based on both ESP pre-flight radiometric calibration and the SDO EVE calibration rocket un-derflight (5 May 2010) measurements obtained with the ESP and Multiple EUV Grating Spec-trometers (MEGS), which are clones of the SDO EVE onboard instruments. SDO/EVE/ESP absolute solar EUV irradiances are compared with the SOHO/CELIAS Solar EUV Monitor (SEM) data to provide uninterrupted EUV measurements of solar irradiances since 1996. The continuing EUV measurements from SDO/EVE/ESP will advance our study of long-and short-term solar EUV variability, improve existing solar EUV irradiance models, and use as input for improving ionosphere and thermosphere model results.

  19. Comparison of the Fourier transform infrared (FTIR) spectrophotometer and the Miniature Infrared Analyzer (MIRAN) for the determination of trichloroethylene (TCE) in the presence of Freon-113 in workplace air

    SciTech Connect

    Xiao, H.K.; Levine, S.P.; D'Arcy, J.B.; Kinnes, G.; Almaguer, D. )

    1990-07-01

    Results obtained using the Fourier transform infrared spectrophotometer (FTIR) and the Miniature Infrared Analyzer (MIRAN) for samples of workplace air containing trichloroethylene (TCE) were evaluated through comparison with results obtained when using a gas chromatography (GC). The effects of instrument resolution, relative humidity, and sample storage stability were studied. Relative humidity was found to have no effect on the performance of the FTIR over the range studied. The effect of changing resolution is complex but is explained. The linear range of the FTIR is more than adequate for the concentrations encountered in the samples reported in this study. Interference from Freon caused the TCE values to be high when the MIRAN was operated in the single-wavelength mode.

  20. 12 CFR 225.41 - Transactions requiring prior notice.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... includes a person's father, mother, stepfather, stepmother, brother, sister, stepbrother, stepsister, son, daughter, stepson, stepdaughter, grandparent, grandson, granddaughter, father-in-law, mother-in-law... person's spouse. (c) Acquisitions requiring prior notice—(1) Acquisition of control. The acquisition...

  1. 12 CFR 225.41 - Transactions requiring prior notice.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... includes a person's father, mother, stepfather, stepmother, brother, sister, stepbrother, stepsister, son, daughter, stepson, stepdaughter, grandparent, grandson, granddaughter, father-in-law, mother-in-law... person's spouse. (c) Acquisitions requiring prior notice—(1) Acquisition of control. The acquisition...

  2. 5 CFR 3301.103 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... ETHICAL CONDUCT FOR EMPLOYEES OF THE DEPARTMENT OF ENERGY § 3301.103 Prior approval for outside employment... statute or Federal regulation, including 5 CFR part 2635. (c) Definition of employment. For purposes of... professional services or are for compensation....

  3. 30. Prior to 1969 PORT SIDE VIEW WHILE DOCKED AT ...

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

    30. Prior to 1969 PORT SIDE VIEW WHILE DOCKED AT CURTIS BAY YARD, BALTIMORE, MARYLAND. - U.S. Coast Guard Cutter WHITE SAGE, U.S. Coast Guard 1st District Base, 1 Thames Street, Bristol, Bristol County, RI

  4. Where is the light? Bayesian perceptual priors for lighting direction.

    PubMed

    Stone, J V; Kerrigan, I S; Porrill, J

    2009-05-22

    Perception of shaded three-dimensional figures is inherently ambiguous, but this ambiguity can be resolved if the brain assumes that figures are lit from a specific direction. Under the Bayesian framework, the visual system assigns a weighting to each possible direction, and these weightings define a prior probability distribution for light-source direction. Here, we describe a non-parametric maximum-likelihood estimation method for finding the prior distribution for lighting direction. Our results suggest that each observer has a distinct prior distribution, with non-zero values in all directions, but with a peak which indicates observers are biased to expect light to come from above left. The implications of these results for estimating general perceptual priors are discussed.

  5. 3. PERSPECTIVE VIEW OF HOUSE FROM SOUTHEAST, PRIOR TO THE ...

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

    3. PERSPECTIVE VIEW OF HOUSE FROM SOUTHEAST, PRIOR TO THE ALTERATIONS OF 1908, SHOWING ADDITION OF FULL LATTICE WORK SCREENING FOUNDATIONS - Ralph M. Munroe House, 3485 Main Highway, Coconut Grove, Miami, Miami-Dade County, FL

  6. Prior knowledge and correlational structure in unsupervised learning.

    PubMed

    Clapper, John P

    2007-06-01

    Prior knowledge has been shown to facilitate both supervised and unsupervised category learning, but questions remain about how this facilitation occurs. This article describes two experiments that investigate the effects of prior knowledge on unsupervised learning, using the exemplar-memory task of Clapper and Bower (2002). Experiment 1 demonstrates that prior knowledge facilitates learning in this task, as expected, and that this facilitation extends to both knowledge-relevant and knowledge-irrelevant features of the new categories. Experiment 2 shows that knowledge facilitates learning not only by increasing the probability that people will discover separate categories, but also by making the features of different categories seem less interchangeable, thereby reducing interference and confusion among them. Taken together, these experiments demonstrate that prior knowledge has multiple effects on unsupervised learning and suggests that the exemplar-memory task may provide a useful procedure for disentangling and investigating these effects.

  7. Spatial prior in SVM-based classification of brain images

    NASA Astrophysics Data System (ADS)

    Cuingnet, Rémi; Chupin, Marie; Benali, Habib; Colliot, Olivier

    2010-03-01

    This paper introduces a general framework for spatial prior in SVM-based classification of brain images based on Laplacian regularization. Most existing methods include spatial prior by adding a feature aggregation step before the SVM classification. The problem of the aggregation step is that the individual information of each feature is lost. Our framework enables to avoid this shortcoming by including the spatial prior directly in the SVM. We demonstrate that this framework can be used to derive embedded regularization corresponding to existing methods for classification of brain images and propose an efficient way to implement them. This framework is illustrated on the classification of MR images from 55 patients with Alzheimer's disease and 82 elderly controls selected from the ADNI database. The results demonstrate that the proposed algorithm enables introducing straightforward and anatomically consistent spatial prior into the classifier.

  8. 1. VIEW OF ARIZONA FALLS ON THE ARIZONA CANAL, PRIOR ...

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

    1. VIEW OF ARIZONA FALLS ON THE ARIZONA CANAL, PRIOR TO CONSTRUCTION OF POWER PLANT IN 1901, FACING EAST Photographer: unknown. No date. - Arizona Canal, North of Salt River, Phoenix, Maricopa County, AZ

  9. Optimized Bayes variational regularization prior for 3D PET images.

    PubMed

    Rapisarda, Eugenio; Presotto, Luca; De Bernardi, Elisabetta; Gilardi, Maria Carla; Bettinardi, Valentino

    2014-09-01

    A new prior for variational Maximum a Posteriori regularization is proposed to be used in a 3D One-Step-Late (OSL) reconstruction algorithm accounting also for the Point Spread Function (PSF) of the PET system. The new regularization prior strongly smoothes background regions, while preserving transitions. A detectability index is proposed to optimize the prior. The new algorithm has been compared with different reconstruction algorithms such as 3D-OSEM+PSF, 3D-OSEM+PSF+post-filtering and 3D-OSL with a Gauss-Total Variation (GTV) prior. The proposed regularization allows controlling noise, while maintaining good signal recovery; compared to the other algorithms it demonstrates a very good compromise between an improved quantitation and good image quality. PMID:24958594

  10. 12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ...

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

    12. VIEW EAST ALONG DECK CENTERLINE, PRIOR TO CANTILEVERING SIDEWALK ON DOWNSTREAM SIDE File photo, Caltrans Office of Strutures Maintenance, March 1938. Photographer unknown. Photocopy of photograph - San Roque Canyon Bridge, State Highway 192, Santa Barbara, Santa Barbara County, CA

  11. Process to upgrade coal liquids by extraction prior to hydrodenitrogenation

    DOEpatents

    Schneider, Abraham; Hollstein, Elmer J.; Janoski, Edward J.; Scheibel, Edward G.

    1982-01-01

    Oxygen compounds are removed, e.g., by extraction, from a coal liquid prior to its hydrogenation. As a result, compared to hydrogenation of such a non-treated coal liquid, the rate of nitrogen removal is increased.

  12. 34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION ...

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

    34. VIEW OF SUBMARINE ESCAPE TRAINING TANK PRIOR TO ADDITION OF BLISTERS IN 1959, LOOKING SOUTHEAST - U.S. Naval Submarine Base, New London Submarine Escape Training Tank, Albacore & Darter Roads, Groton, New London County, CT

  13. 47 CFR 25.118 - Modifications not requiring prior authorization.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....118 Modifications not requiring prior authorization. (a) Earth station license modifications, notification required. Authorized earth station operators may make the following modifications to their... of part 1, subpart Y of this chapter: (1) Licensees may make changes to their authorized...

  14. 47 CFR 25.118 - Modifications not requiring prior authorization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ....118 Modifications not requiring prior authorization. (a) Earth station license modifications, notification required. Authorized earth station operators may make the following modifications to their... of part 1, subpart Y of this chapter: (1) Licensees may make changes to their authorized...

  15. 47 CFR 25.118 - Modifications not requiring prior authorization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....118 Modifications not requiring prior authorization. (a) Earth station license modifications, notification required. Authorized earth station operators may make the following modifications to their... of part 1, subpart Y of this chapter: (1) Licensees may make changes to their authorized...

  16. 47 CFR 25.118 - Modifications not requiring prior authorization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....118 Modifications not requiring prior authorization. (a) Earth station license modifications, notification required. Authorized earth station operators may make the following modifications to their... of part 1, subpart Y of this chapter: (1) Licensees may make changes to their authorized...

  17. 47 CFR 25.118 - Modifications not requiring prior authorization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ....118 Modifications not requiring prior authorization. (a) Earth station license modifications, notification required. Authorized earth station operators may make the following modifications to their... of part 1, subpart Y of this chapter: (1) Licensees may make changes to their authorized...

  18. U.S. Teen Diabetes Rate Exceeds Prior Estimates

    MedlinePlus

    ... https://medlineplus.gov/news/fullstory_159953.html U.S. Teen Diabetes Rate Exceeds Prior Estimates Most young people ... TUESDAY, July 19, 2016 (HealthDay News) -- More American teens have diabetes or prediabetes than previously thought, and ...

  19. A Bayesian Approach for Image Segmentation with Shape Priors

    SciTech Connect

    Chang, Hang; Yang, Qing; Parvin, Bahram

    2008-06-20

    Color and texture have been widely used in image segmentation; however, their performance is often hindered by scene ambiguities, overlapping objects, or missingparts. In this paper, we propose an interactive image segmentation approach with shape prior models within a Bayesian framework. Interactive features, through mouse strokes, reduce ambiguities, and the incorporation of shape priors enhances quality of the segmentation where color and/or texture are not solely adequate. The novelties of our approach are in (i) formulating the segmentation problem in a well-de?ned Bayesian framework with multiple shape priors, (ii) ef?ciently estimating parameters of the Bayesian model, and (iii) multi-object segmentation through user-speci?ed priors. We demonstrate the effectiveness of our method on a set of natural and synthetic images.

  20. 38 CFR 17.54 - Necessity for prior authorization.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MEDICAL Use of Public Or Private Hospitals § 17.54 Necessity for prior authorization. (a) The admission of... must be authorized in advance. In the case of an emergency which existed at the time of admission,...

  1. 67. VAL BRIDGE AND BARGES PRIOR TO CONNECTING TO SUPPORT ...

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

    67. VAL BRIDGE AND BARGES PRIOR TO CONNECTING TO SUPPORT CARRIAGE, April 12, 1948. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  2. Historic view of Nooksack Falls, taken in 1904 prior to ...

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

    Historic view of Nooksack Falls, taken in 1904 prior to construction of the hydroelectric project. (J.B. Hahn, photographer, 1904.) - Nooksack Falls Hydroelectric Plant, Route 542, Glacier, Whatcom County, WA

  3. 13. INTERIOR VIEW, DETAIL OF METERED WARNING BELL (PRIOR TO ...

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

    13. INTERIOR VIEW, DETAIL OF METERED WARNING BELL (PRIOR TO ARRIVAL OF TRAINS), LOCATED IN TICKET OFFICE, SOUTHWEST WALL - Baltimore & Ohio Railroad Station, Laurel, 101 Lafayette Avenue, Laurel, Prince George's County, MD

  4. 54. CLEARANCE OF SITE PRIOR TO CONSTRUCTION OF BREAKER BUILDING, ...

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

    54. CLEARANCE OF SITE PRIOR TO CONSTRUCTION OF BREAKER BUILDING, AND CONSTRUCTION OF EMBANKMENT FOR RAILROAD SPUR. c.1898 (AKZO No. A-3) - Avery Island Salt Works, Akzo Salt Incorporated, Avery Island, Iberia Parish, LA

  5. Influences of prior knowledge on selective weighting of category members.

    PubMed

    Heit, E

    1998-05-01

    Three experiments addressed how prior theories affect categorization, comparing the influence of theory-congruent versus theory-incongruent category members. Subjects observed descriptions of persons, some congruent with prior knowledge and some incongruent, then made transfer judgments. In Experiment 1, subjects were given a relatively long time to study each description, whereas in Experiment 2 study time was manipulated between subjects. In Experiment 3, learning was self-paced by each subject. It was found that, with enough study time, prior knowledge had 2 distinct influences. First, prior knowledge provided an initial representation, subsequently revised in light of new observations. Second, incongruent observations had more impact than congruent observations on categorization. In comparison, when study time was more limited, revision proceeded in a Bayesian manner, in that congruent and incongruent observations had equal impacts.

  6. Does Prior Shoulder Surgery Negatively Impact Shoulder Arthroplasty Outcomes?

    PubMed Central

    Frank, Rachel M.; Aiyash, Sal; Kupfer, Noam; Tilton, Annemarie K.; Cole, Brian J.; Verma, Nikhil N.; Nicholson, Gregory P.; Romeo, Anthony A.

    2015-01-01

    Objectives: Several studies have shown a negative correlation between prior knee arthroscopy and ultimate knee arthroplasty outcomes compared to patients without prior arthroscopy. The purpose of this study was to determine the effects of prior shoulder surgery on patients undergoing total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (rTSA) compared to patients without prior shoulder surgery. Methods: A retrospective review of prospectively collected data was performed on 107 patients undergoing TSA or rTSA. All medical records were analyzed for demographic variables, type of prior shoulder surgery, and type of arthroplasty. All patients underwent a clinical follow-up evaluation, and were evaluated with the American Shoulder and Elbow Society (ASES), Simple Shoulder Test (SST), and Visual Analog Scale (VAS) outcomes scores. Complications, failures, and reoperations were also recorded an analyzed. Results: A total of 107 patients (47 males, 60 females) were included with an average follow-up of 24 months (minimum 12 months). Seventy-one patients (underwent arthroplasty without prior surgery (30 rTSA, 41 TSA) while 50 patients underwent arthroplasty with a history of at least one prior shoulder surgery (27 rTSA, 9 TSA). Prior surgeries included a mix of both open and arthroscopic procedures, including open and arthroscopic rotator cuff repair, open and arthroscopic stabilization (with and without bone augmentation), arthroscopic capsular release, and arthroscopic debridement. Following arthroplasty, both groups experienced significant improvements in ASES, SST, and VAS scores compared to preoperative scores (P<0.05 for all). There was a statistically significant difference in postoperative ASES scores in the no-surgery group compared to the prior-surgery group (84.49 versus 71.67, P=0.0003) as well as in the SST scores (8.97 versus 5.47, P<0.0001); there were no differences in the VAS score (0.83 vs 1.40, P=0.104). Conclusion: Shoulder

  7. 33 CFR 114.25 - Work constructed without prior authority.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... is begun. (5 U.S.C. 559; 14 U.S.C. 633; 33 U.S.C. 401, 491, 499, and 525; and 49 CFR 1.46(c) and (q)) ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Work constructed without prior... SECURITY BRIDGES GENERAL § 114.25 Work constructed without prior authority. The Commandant or...

  8. Wild geese do not increase flight behaviour prior to migration.

    PubMed

    Portugal, Steven J; Green, Jonathan A; White, Craig R; Guillemette, Magella; Butler, Patrick J

    2012-06-23

    Hypertrophy of the flight muscles is regularly observed in birds prior to long-distance migrations. We tested the hypothesis that a large migratory bird would increase flight behaviour prior to migration, in order to cause hypertrophy of the flight muscles, and upregulate key components of the aerobic metabolic pathways. Implantable data loggers were used to record year-round heart rate in six wild barnacle geese (Branta leucopsis), and the amount of time spent in flight each day was identified. Time in flight per day did not significantly increase prior to either the spring or the autumn migration, both between time periods prior to migration (5, 10 and 15 days), or when compared with a control period of low activity during winter. The lack of significant increase in flight prior to migration suggests that approximately 22 min per day is sufficient to maintain the flight muscles in condition for prolonged long-distance flight. This apparent lack of a requirement for increased flight activity prior to migration may be attributable to pre-migratory mass gains in the geese increasing workload during short flights, potentially prompting hypertrophy of the flight muscles.

  9. Improving parameter priors for data-scarce estimation problems

    NASA Astrophysics Data System (ADS)

    Almeida, Susana; Bulygina, Nataliya; McIntyre, Neil; Wagener, Thorsten; Buytaert, Wouter

    2013-09-01

    Runoff prediction in ungauged catchments is a recurrent problem in hydrology. Conceptual models are usually calibrated by defining a feasible parameter range and then conditioning parameter sets on observed system responses, e.g., streamflow. In ungauged catchments, several studies condition models on regionalized response signatures, such as runoff ratio or base flow index, using a Bayesian procedure. In this technical note, the Model Parameter Estimation Experiment (MOPEX) data set is used to explore the impact on model performance of assumptions made about the prior distribution. In particular, the common assumption of uniform prior on parameters is shown to be unsuitable. This is because the uniform prior on parameters maps onto skewed response signature priors that can counteract the valuable information gained from the regionalization. To address this issue, we test a methodological development based on an initial transformation of the uniform prior on parameters into a prior that maps to a uniform response signature distribution. We demonstrate that this method contributes to improved estimation of the response signatures.

  10. Prior Knowledge Improves Decoding of Finger Flexion from Electrocorticographic Signals

    PubMed Central

    Wang, Z.; Ji, Q.; Miller, K. J.; Schalk, Gerwin

    2011-01-01

    Brain–computer interfaces (BCIs) use brain signals to convey a user’s intent. Some BCI approaches begin by decoding kinematic parameters of movements from brain signals, and then proceed to using these signals, in absence of movements, to allow a user to control an output. Recent results have shown that electrocorticographic (ECoG) recordings from the surface of the brain in humans can give information about kinematic parameters (e.g., hand velocity or finger flexion). The decoding approaches in these studies usually employed classical classification/regression algorithms that derive a linear mapping between brain signals and outputs. However, they typically only incorporate little prior information about the target movement parameter. In this paper, we incorporate prior knowledge using a Bayesian decoding method, and use it to decode finger flexion from ECoG signals. Specifically, we exploit the constraints that govern finger flexion and incorporate these constraints in the construction, structure, and the probabilistic functions of the prior model of a switched non-parametric dynamic system (SNDS). Given a measurement model resulting from a traditional linear regression method, we decoded finger flexion using posterior estimation that combined the prior and measurement models. Our results show that the application of the Bayesian decoding model, which incorporates prior knowledge, improves decoding performance compared to the application of a linear regression model, which does not incorporate prior knowledge. Thus, the results presented in this paper may ultimately lead to neurally controlled hand prostheses with full fine-grained finger articulation. PMID:22144944

  11. Spiked Dirichlet Process Priors for Gaussian Process Models

    PubMed Central

    Savitsky, Terrance; Vannucci, Marina

    2013-01-01

    We expand a framework for Bayesian variable selection for Gaussian process (GP) models by employing spiked Dirichlet process (DP) prior constructions over set partitions containing covariates. Our approach results in a nonparametric treatment of the distribution of the covariance parameters of the GP covariance matrix that in turn induces a clustering of the covariates. We evaluate two prior constructions: the first one employs a mixture of a point-mass and a continuous distribution as the centering distribution for the DP prior, therefore, clustering all covariates. The second one employs a mixture of a spike and a DP prior with a continuous distribution as the centering distribution, which induces clustering of the selected covariates only. DP models borrow information across covariates through model-based clustering. Our simulation results, in particular, show a reduction in posterior sampling variability and, in turn, enhanced prediction performances. In our model formulations, we accomplish posterior inference by employing novel combinations and extensions of existing algorithms for inference with DP prior models and compare performances under the two prior constructions. PMID:23950763

  12. Identification of subsurface structures using electromagnetic data and shape priors

    SciTech Connect

    Tveit, Svenn; Bakr, Shaaban A.; Lien, Martha; Mannseth, Trond

    2015-03-01

    We consider the inverse problem of identifying large-scale subsurface structures using the controlled source electromagnetic method. To identify structures in the subsurface where the contrast in electric conductivity can be small, regularization is needed to bias the solution towards preserving structural information. We propose to combine two approaches for regularization of the inverse problem. In the first approach we utilize a model-based, reduced, composite representation of the electric conductivity that is highly flexible, even for a moderate number of degrees of freedom. With a low number of parameters, the inverse problem is efficiently solved using a standard, second-order gradient-based optimization algorithm. Further regularization is obtained using structural prior information, available, e.g., from interpreted seismic data. The reduced conductivity representation is suitable for incorporation of structural prior information. Such prior information cannot, however, be accurately modeled with a gaussian distribution. To alleviate this, we incorporate the structural information using shape priors. The shape prior technique requires the choice of kernel function, which is application dependent. We argue for using the conditionally positive definite kernel which is shown to have computational advantages over the commonly applied gaussian kernel for our problem. Numerical experiments on various test cases show that the methodology is able to identify fairly complex subsurface electric conductivity distributions while preserving structural prior information during the inversion.

  13. Hydrogen absorption in iron exposed to simulated concrete pore solutions

    SciTech Connect

    Lillard, R.S.; Scully, J.R.

    1996-02-01

    Safe cathodic protection (CP) limits are required for prestressed steel in concrete to avoid the risk of hydrogen embrittlement (HE). This preliminary study addressed some effects of concrete pore solution chemistry and metal surface condition on hydrogen absorption in iron. To accomplish this, the Devanathan-Stachurski permeation technique was used to investigate hydrogen absorption in 99.5% iron foils exposed to NaOH, saturated Ca(OH){sub 2}, and saturated Ca(OH){sub 2} + 0.6 M NaCl, all at pH 12.5. The foils used in this investigation were tested after various surface preparations: (a) polished, (b) with a thermal oxide formed by a heat treatment designed to simulate the stress relief oxide, and (c) with corrosion films to simulate an inservice tendon that was exposed to a marine environment for some time prior to CP. Hydrogen uptake in iron was most efficient for foils covered with Portland cement-based mortar, at least 2.5 times greater than that in NaOH of the same pH and hydrogen production rate. Absorption in saturated Ca(OH){sub 2} was somewhat less than that from the mortar cover. While chloride had no direct effect on the hydrogen absorption rate, the corrosion product and the thermal oxide were found to decrease hydrogen absorption compared to polished iron. The thermal oxide acted as a complete barrier at all charging current densities investigated. The effectiveness of this thermal oxide barrier to hydrogen, however, was compromised by corrosion resulting from alternate immersion exposure to a chloride environment.

  14. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  15. Finding a Minimally Informative Dirichlet Prior Distribution Using Least Squares

    SciTech Connect

    Dana Kelly; Corwin Atwood

    2011-03-01

    In a Bayesian framework, the Dirichlet distribution is the conjugate distribution to the multinomial likelihood function, and so the analyst is required to develop a Dirichlet prior that incorporates available information. However, as it is a multiparameter distribution, choosing the Dirichlet parameters is less straight-forward than choosing a prior distribution for a single parameter, such as p in the binomial distribution. In particular, one may wish to incorporate limited information into the prior, resulting in a minimally informative prior distribution that is responsive to updates with sparse data. In the case of binomial p or Poisson, the principle of maximum entropy can be employed to obtain a so-called constrained noninformative prior. However, even in the case of p, such a distribution cannot be written down in closed form, and so an approximate beta distribution is used in the case of p. In the case of the multinomial model with parametric constraints, the approach of maximum entropy does not appear tractable. This paper presents an alternative approach, based on constrained minimization of a least-squares objective function, which leads to a minimally informative Dirichlet prior distribution. The alpha-factor model for common-cause failure, which is widely used in the United States, is the motivation for this approach, and is used to illustrate the method. In this approach to modeling common-cause failure, the alpha-factors, which are the parameters in the underlying multinomial aleatory model for common-cause failure, must be estimated from data that is often quite sparse, because common-cause failures tend to be rare, especially failures of more than two or three components, and so a prior distribution that is responsive to updates with sparse data is needed.

  16. Finding A Minimally Informative Dirichlet Prior Using Least Squares

    SciTech Connect

    Dana Kelly

    2011-03-01

    In a Bayesian framework, the Dirichlet distribution is the conjugate distribution to the multinomial likelihood function, and so the analyst is required to develop a Dirichlet prior that incorporates available information. However, as it is a multiparameter distribution, choosing the Dirichlet parameters is less straightforward than choosing a prior distribution for a single parameter, such as p in the binomial distribution. In particular, one may wish to incorporate limited information into the prior, resulting in a minimally informative prior distribution that is responsive to updates with sparse data. In the case of binomial p or Poisson \\lambda, the principle of maximum entropy can be employed to obtain a so-called constrained noninformative prior. However, even in the case of p, such a distribution cannot be written down in the form of a standard distribution (e.g., beta, gamma), and so a beta distribution is used as an approximation in the case of p. In the case of the multinomial model with parametric constraints, the approach of maximum entropy does not appear tractable. This paper presents an alternative approach, based on constrained minimization of a least-squares objective function, which leads to a minimally informative Dirichlet prior distribution. The alpha-factor model for common-cause failure, which is widely used in the United States, is the motivation for this approach, and is used to illustrate the method. In this approach to modeling common-cause failure, the alpha-factors, which are the parameters in the underlying multinomial model for common-cause failure, must be estimated from data that are often quite sparse, because common-cause failures tend to be rare, especially failures of more than two or three components, and so a prior distribution that is responsive to updates with sparse data is needed.

  17. Prior-based artifact correction (PBAC) in computed tomography

    SciTech Connect

    Heußer, Thorsten Brehm, Marcus; Ritschl, Ludwig; Sawall, Stefan; Kachelrieß, Marc

    2014-02-15

    Purpose: Image quality in computed tomography (CT) often suffers from artifacts which may reduce the diagnostic value of the image. In many cases, these artifacts result from missing or corrupt regions in the projection data, e.g., in the case of metal, truncation, and limited angle artifacts. The authors propose a generalized correction method for different kinds of artifacts resulting from missing or corrupt data by making use of available prior knowledge to perform data completion. Methods: The proposed prior-based artifact correction (PBAC) method requires prior knowledge in form of a planning CT of the same patient or in form of a CT scan of a different patient showing the same body region. In both cases, the prior image is registered to the patient image using a deformable transformation. The registered prior is forward projected and data completion of the patient projections is performed using smooth sinogram inpainting. The obtained projection data are used to reconstruct the corrected image. Results: The authors investigate metal and truncation artifacts in patient data sets acquired with a clinical CT and limited angle artifacts in an anthropomorphic head phantom data set acquired with a gantry-based flat detector CT device. In all cases, the corrected images obtained by PBAC are nearly artifact-free. Compared to conventional correction methods, PBAC achieves better artifact suppression while preserving the patient-specific anatomy at the same time. Further, the authors show that prominent anatomical details in the prior image seem to have only minor impact on the correction result. Conclusions: The results show that PBAC has the potential to effectively correct for metal, truncation, and limited angle artifacts if adequate prior data are available. Since the proposed method makes use of a generalized algorithm, PBAC may also be applicable to other artifacts resulting from missing or corrupt data.

  18. Advanced prior modeling for 3D bright field electron tomography

    NASA Astrophysics Data System (ADS)

    Sreehari, Suhas; Venkatakrishnan, S. V.; Drummy, Lawrence F.; Simmons, Jeffrey P.; Bouman, Charles A.

    2015-03-01

    Many important imaging problems in material science involve reconstruction of images containing repetitive non-local structures. Model-based iterative reconstruction (MBIR) could in principle exploit such redundancies through the selection of a log prior probability term. However, in practice, determining such a log prior term that accounts for the similarity between distant structures in the image is quite challenging. Much progress has been made in the development of denoising algorithms like non-local means and BM3D, and these are known to successfully capture non-local redundancies in images. But the fact that these denoising operations are not explicitly formulated as cost functions makes it unclear as to how to incorporate them in the MBIR framework. In this paper, we formulate a solution to bright field electron tomography by augmenting the existing bright field MBIR method to incorporate any non-local denoising operator as a prior model. We accomplish this using a framework we call plug-and-play priors that decouples the log likelihood and the log prior probability terms in the MBIR cost function. We specifically use 3D non-local means (NLM) as the prior model in the plug-and-play framework, and showcase high quality tomographic reconstructions of a simulated aluminum spheres dataset, and two real datasets of aluminum spheres and ferritin structures. We observe that streak and smear artifacts are visibly suppressed, and that edges are preserved. Also, we report lower RMSE values compared to the conventional MBIR reconstruction using qGGMRF as the prior model.

  19. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  20. Use of prior odds for missing persons identifications.

    PubMed

    Budowle, Bruce; Ge, Jianye; Chakraborty, Ranajit; Gill-King, Harrell

    2011-06-27

    Identification of missing persons from mass disasters is based on evaluation of a number of variables and observations regarding the combination of features derived from these variables. DNA typing now is playing a more prominent role in the identification of human remains, and particularly so for highly decomposed and fragmented remains. The strength of genetic associations, by either direct or kinship analyses, is often quantified by calculating a likelihood ratio. The likelihood ratio can be multiplied by prior odds based on nongenetic evidence to calculate the posterior odds, that is, by applying Bayes' Theorem, to arrive at a probability of identity. For the identification of human remains, the path creating the set and intersection of variables that contribute to the prior odds needs to be appreciated and well defined. Other than considering the total number of missing persons, the forensic DNA community has been silent on specifying the elements of prior odds computations. The variables include the number of missing individuals, eyewitness accounts, anthropological features, demographics and other identifying characteristics. The assumptions, supporting data and reasoning that are used to establish a prior probability that will be combined with the genetic data need to be considered and justified. Otherwise, data may be unintentionally or intentionally manipulated to achieve a probability of identity that cannot be supported and can thus misrepresent the uncertainty with associations. The forensic DNA community needs to develop guidelines for objectively computing prior odds.

  1. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging

    PubMed Central

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  2. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    PubMed

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  3. Ligand placement based on prior structures: the guided ligand-replacement method

    SciTech Connect

    Klei, Herbert E.; Moriarty, Nigel W. Echols, Nathaniel; Terwilliger, Thomas C.; Baldwin, Eric T.; Pokross, Matt; Posy, Shana; Adams, Paul D.

    2014-01-01

    A new module, Guided Ligand Replacement (GLR), has been developed in Phenix to increase the ease and success rate of ligand placement when prior protein-ligand complexes are available. The process of iterative structure-based drug design involves the X-ray crystal structure determination of upwards of 100 ligands with the same general scaffold (i.e. chemotype) complexed with very similar, if not identical, protein targets. In conjunction with insights from computational models and assays, this collection of crystal structures is analyzed to improve potency, to achieve better selectivity and to reduce liabilities such as absorption, distribution, metabolism, excretion and toxicology. Current methods for modeling ligands into electron-density maps typically do not utilize information on how similar ligands bound in related structures. Even if the electron density is of sufficient quality and resolution to allow de novo placement, the process can take considerable time as the size, complexity and torsional degrees of freedom of the ligands increase. A new module, Guided Ligand Replacement (GLR), was developed in Phenix to increase the ease and success rate of ligand placement when prior protein–ligand complexes are available. At the heart of GLR is an algorithm based on graph theory that associates atoms in the target ligand with analogous atoms in the reference ligand. Based on this correspondence, a set of coordinates is generated for the target ligand. GLR is especially useful in two situations: (i) modeling a series of large, flexible, complicated or macrocyclic ligands in successive structures and (ii) modeling ligands as part of a refinement pipeline that can automatically select a reference structure. Even in those cases for which no reference structure is available, if there are multiple copies of the bound ligand per asymmetric unit GLR offers an efficient way to complete the model after the first ligand has been placed. In all of these applications, GLR

  4. Investigation of absorption spectra of Gafchromic EBT2 film's components and their impact on UVR dosimetry

    NASA Astrophysics Data System (ADS)

    Aydarous, Abdulkadir

    2016-05-01

    The absorption spectra of the EBT2 film's components were investigated in conjunction with its use for UVA dosimetry. The polyester (topside) and adhesive layers of the EBT2 film have been gently removed. Gafchromic™ EBT2 films with and without the protected layers (polyester and adhesive) were exposed to UVR of 365 nm for different durations. Thereafter, the UV-visible spectra were measured using a UV-visible spectrophotometer (Model Spectro Dual Split Beam, UVS-2700). Films were digitized using a Nikon CanoScan 9000F Mark II flatbed scanner. The dosimetric characteristics including film's uniformity, reproducibility and post-irradiation development were investigated. The color development of EBT2 and new modified EBT2 (EBT2-M) films irradiated with UVA was relatively stable (less than 1%) immediately after exposure. Based on this study, the sensitivity of EBT2 to UVR with wavelength between ~350 nm and ~390 nm can significantly be enhanced if the adhesive layer (~25 μm) is removed. The polyester layer plays almost no part on absorbing UVR with wavelength between ~320 nm and ~390 nm. Furthermore, various sensitivities for the EBT2-M film has been established depending on the wavelength of analysis.

  5. Measurement of aluminum in neuronal tissues using electrothermal atomization atomic absorption spectrophotometry

    SciTech Connect

    Pierson, K.B.; Evenson, M.A.

    1986-07-01

    Studies characterizing aluminum complexes isolated from neuronal tissues require accurate and precise techniques for aluminum measurement. A solution of 0.01 M nitric acid containing 0.2% Triton X-100 was the optimal diluent for aluminum measurement under the experimental conditions used. Three National Bureau of Standards Standard Reference Materials (SRM) were digested, and the aluminum concentration of each was measured with a Perkin-Elmer 503 atomic absorption spectrophotometer equipped with a Perkin-Elmer HGA 2100 controller. The calculated detection limit of aluminum was 120 pg using 15-..mu..L sample injections (8 ..mu..g/L). Aluminum concentrations present in citrus leaves (SRM 1572), pine needles (SRM 1575), and tomato leaves (SRM 1573) were 100 +- 12 (certified value, 92 +- 15), 522 +- 45 (certified value, 454 +- 30), and 1273 +- 112 (provisional value, 1200) ..mu..g/g, respectively. The within- and between-day precision had coefficients of variation for citrus leaves, pine needles, and tomato leaves of 18 and 12%, 6.3 and 8.6%, and 3.7 and 8.7%, respectively. Aluminum absorbance was enhanced at high pH values and by zinc.

  6. Gastrointestinal absorption of protactinium, uranium, and neptunium in the hamster

    SciTech Connect

    Harrison, J.D.; Stather, J.W.

    1981-10-01

    The gastrointestinal absorption of protactinium, uranium, and neptunium in adult hamsters was measured. The actinide preparations were administered intragastrically and animals were kept 2 to 4 weeks prior to the radiochemical analysis of selected tissue samples. Total absorption was estimated using data for the distribution of the actinides after intravenous injection in soluble form. The values obtained were 3.9 and 0.22% for /sup 231/Pa citrate and /sup 231/Pa fluoride, respectively; 0.77 and 0.11% for /sup 233/U (uranyl) nitrate and /sup 233/U dioxide, respectively; and 0.06 and 0.05% for /sup 237/Np citrate and /sup 237/Np nitrate, respectively. The absorption factors recommended by the International Commission on Radiological Protection for use in calculating annual limits on intake for occupationally exposed workers are: 0.1% for all compounds of Pa; 5 and 0.2% for soluble hexavalent and relatively insoluble tetravalent forms of U, respectively; and 1.0% for all chemical forms of Np. The experimental basis for these values is discussed.

  7. Low-frequency absorption of sound in air

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Meredith, R. W.

    1985-01-01

    Thirty sets of sound absorption measurements in air at a pressure of 1 atmosphere are presented at temperatures from 10 C to 50 C, relative humidities from 0 to 100 percent, and frequencies from 10 to 2500 Hz. The measurements were conducted by the method of free decay in a resonant tube having a length of 18.261 m and bore diameter of 0.152 m. Background measurements in a gas consisting of 89.5 percent N2 and 10.5 percent Ar, a mixture which has the same sound velocity as air, permitted the wall and structural losses of the tube to be separated from the constituent absorption, consisting of classical rotational and vibrational absorption, in the air samples. The data were used to evaluate the vibrational relaxation frequencies of N2 and/or O2 for each of the 30 sets of meteorological parameters. Over the full range of humidity, the measured relaxation frequencies of N2 in air lie between those specified by ANSI Standard S1.26-1978 and those measured earlier in binary N2H2O mixtures. The measured relaxation frequencies could be determined only at very low values of humidity, reveal a significant trend away from the ANSI standard, in agreement with a prior investigation.

  8. Low-frequency sound absorption measurements in air

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.; Meredith, R. W.

    1984-01-01

    Thirty sets of sound absorption measurements in air at a pressure of 1 atmosphere are presented at temperatures from 10 C to 50 C, relative humidities from 0 to 100 percent, and frequencies from 10 to 2500 Hz. The measurements were conducted by the method of free decay in a resonant tube having a length of 18.261 m and bore diameter of 0.152 m. Background measurements in a gas consisting of 89.5 percent N2 and 10.5 percent Ar, a mixture which has the same sound velocity as air, permitted the wall and structural losses of the tube to be separated from the constituent absorption, consisting of classical rotational and vibrational absorption, in the air samples. The data were used to evaluate the vibrational relaxation frequencies of N2 and/or O2 for each of the 30 sets of meteorological parameters. Over the full range of humidity, the measured relaxation frequencies of N2 in air lie between those specified by ANSI Standard S1.26-1978 and those measured earlier in binary N2H2O mixtures. The measured relaxation frequencies could be determined only at very low values of humidity, reveal a significant trend away from the ANSI standard, in agreement with a prior investigation.

  9. When does prior knowledge disproportionately benefit older adults' memory?

    PubMed

    Badham, Stephen P; Hay, Mhairi; Foxon, Natasha; Kaur, Kiran; Maylor, Elizabeth A

    2016-01-01

    Material consistent with knowledge/experience is generally more memorable than material inconsistent with knowledge/experience - an effect that can be more extreme in older adults. Four experiments investigated knowledge effects on memory with young and older adults. Memory for familiar and unfamiliar proverbs (Experiment 1) and for common and uncommon scenes (Experiment 2) showed similar knowledge effects across age groups. Memory for person-consistent and person-neutral actions (Experiment 3) showed a greater benefit of prior knowledge in older adults. For cued recall of related and unrelated word pairs (Experiment 4), older adults benefited more from prior knowledge only when it provided uniquely useful additional information beyond the episodic association itself. The current data and literature suggest that prior knowledge has the age-dissociable mnemonic properties of (1) improving memory for the episodes themselves (age invariant), and (2) providing conceptual information about the tasks/stimuli extrinsically to the actual episodic memory (particularly aiding older adults). PMID:26473767

  10. Quintessence in a quandary: Prior dependence in dark energy models

    NASA Astrophysics Data System (ADS)

    Marsh, David J. E.; Bull, Philip; Ferreira, Pedro G.; Pontzen, Andrew

    2014-11-01

    The archetypal theory of dark energy is quintessence: a minimally coupled scalar field with a canonical kinetic energy and potential. By studying random potentials, we show that quintessence imposes a restricted set of priors on the equation of state of dark energy. Focusing on the commonly used parametrization, w (a )≈w0+wa(1 -a ) , we show that there is a natural scale and direction in the (w0,wa) plane that distinguishes quintessence as a general framework. We calculate the expected information gain for a given survey and show that, because of the nontrivial prior information, it is a function of more than just the figure of merit. This allows us to make a quantitative case for novel survey strategies. We show that the scale of the prior sets target observational requirements for gaining significant information. This corresponds to a figure of merit FOM ≳200 , a requirement that future galaxy redshift surveys will meet.

  11. Expected behavior of quantum thermodynamic machines with prior information.

    PubMed

    Thomas, George; Johal, Ramandeep S

    2012-04-01

    We estimate the expected behavior of the quantum model of a heat engine when we have incomplete information about external macroscopic parameters such as the magnetic field controlling the intrinsic energy scales of the working medium. We explicitly derive the prior probability distribution for these unknown parameters ai (i=1,2). Based on a few simple assumptions, the prior probability distribution is found to be of the form Π(ai)∝1/ai. By calculating the expected values of various physical quantities related to this engine, we find that the expected behavior of the quantum model exhibits thermodynamiclike features. This leads us to a surprising proposal that incomplete information quantified as an appropriate prior distribution can lead us to expect classical thermodynamic behavior in quantum models.

  12. Noninformative prior in the quantum statistical model of pure states

    NASA Astrophysics Data System (ADS)

    Tanaka, Fuyuhiko

    2012-06-01

    In the present paper, we consider a suitable definition of a noninformative prior on the quantum statistical model of pure states. While the full pure-states model is invariant under unitary rotation and admits the Haar measure, restricted models, which we often see in quantum channel estimation and quantum process tomography, have less symmetry and no compelling rationale for any choice. We adopt a game-theoretic approach that is applicable to classical Bayesian statistics and yields a noninformative prior for a general class of probability distributions. We define the quantum detection game and show that there exist noninformative priors for a general class of a pure-states model. Theoretically, it gives one of the ways that we represent ignorance on the given quantum system with partial information. Practically, our method proposes a default distribution on the model in order to use the Bayesian technique in the quantum-state tomography with a small sample.

  13. Integrating Informative Priors from Experimental Research with Bayesian Methods

    PubMed Central

    Hamra, Ghassan; Richardson, David; MacLehose, Richard; Wing, Steve

    2013-01-01

    Informative priors can be a useful tool for epidemiologists to handle problems of sparse data in regression modeling. It is sometimes the case that an investigator is studying a population exposed to two agents, X and Y, where Y is the agent of primary interest. Previous research may suggest that the exposures have different effects on the health outcome of interest, one being more harmful than the other. Such information may be derived from epidemiologic analyses; however, in the case where such evidence is unavailable, knowledge can be drawn from toxicologic studies or other experimental research. Unfortunately, using toxicologic findings to develop informative priors in epidemiologic analyses requires strong assumptions, with no established method for its utilization. We present a method to help bridge the gap between animal and cellular studies and epidemiologic research by specification of an order-constrained prior. We illustrate this approach using an example from radiation epidemiology. PMID:23222512

  14. Approximate message passing with restricted Boltzmann machine priors

    NASA Astrophysics Data System (ADS)

    Tramel, Eric W.; Drémeau, Angélique; Krzakala, Florent

    2016-07-01

    Approximate message passing (AMP) has been shown to be an excellent statistical approach to signal inference and compressed sensing problems. The AMP framework provides modularity in the choice of signal prior; here we propose a hierarchical form of the Gauss-Bernoulli prior which utilizes a restricted Boltzmann machine (RBM) trained on the signal support to push reconstruction performance beyond that of simple i.i.d. priors for signals whose support can be well represented by a trained binary RBM. We present and analyze two methods of RBM factorization and demonstrate how these affect signal reconstruction performance within our proposed algorithm. Finally, using the MNIST handwritten digit dataset, we show experimentally that using an RBM allows AMP to approach oracle-support performance.

  15. Absorption, Creativity, Peak Experiences, Empathy, and Psychoticism.

    ERIC Educational Resources Information Center

    Mathes, Eugene W.; And Others

    Tellegen and Atkinson suggested that the trait of absorption may play a part in meditative skill, creativity, capacity for peak experiences, and empathy. Although the absorption-meditative skill relationship has been confirmed, other predictions have not been tested. Tellegen and Atkinson's Absorption Scale was completed by undergraduates in four…

  16. Multiple sparse volumetric priors for distributed EEG source reconstruction.

    PubMed

    Strobbe, Gregor; van Mierlo, Pieter; De Vos, Maarten; Mijović, Bogdan; Hallez, Hans; Van Huffel, Sabine; López, José David; Vandenberghe, Stefaan

    2014-10-15

    We revisit the multiple sparse priors (MSP) algorithm implemented in the statistical parametric mapping software (SPM) for distributed EEG source reconstruction (Friston et al., 2008). In the present implementation, multiple cortical patches are introduced as source priors based on a dipole source space restricted to a cortical surface mesh. In this note, we present a technique to construct volumetric cortical regions to introduce as source priors by restricting the dipole source space to a segmented gray matter layer and using a region growing approach. This extension allows to reconstruct brain structures besides the cortical surface and facilitates the use of more realistic volumetric head models including more layers, such as cerebrospinal fluid (CSF), compared to the standard 3-layered scalp-skull-brain head models. We illustrated the technique with ERP data and anatomical MR images in 12 subjects. Based on the segmented gray matter for each of the subjects, cortical regions were created and introduced as source priors for MSP-inversion assuming two types of head models. The standard 3-layered scalp-skull-brain head models and extended 4-layered head models including CSF. We compared these models with the current implementation by assessing the free energy corresponding with each of the reconstructions using Bayesian model selection for group studies. Strong evidence was found in favor of the volumetric MSP approach compared to the MSP approach based on cortical patches for both types of head models. Overall, the strongest evidence was found in favor of the volumetric MSP reconstructions based on the extended head models including CSF. These results were verified by comparing the reconstructed activity. The use of volumetric cortical regions as source priors is a useful complement to the present implementation as it allows to introduce more complex head models and volumetric source priors in future studies.

  17. High frequency ultrasonic-assisted CO2 absorption in a high pressure water batch system.

    PubMed

    Tay, W H; Lau, K K; Shariff, A M

    2016-11-01

    Physical absorption process is always nullified by the presence of cavitation under low frequency ultrasonic irradiation. In the present study, high frequency ultrasonic of 1.7MHz was used for the physical absorption of CO2 in a water batch system under elevated pressure. The parameters including ultrasonic power and initial feed pressure for the system have been varied from 0 to 18W and 6 to 41bar, respectively. The mass transfer coefficient has been determined via the dynamic pressure-step method. Besides, the actual ultrasonic power that transmitted to the liquid was measured based on calorimetric method prior to the absorption study. Subsequently, desorption study was conducted as a comparison with the absorption process. The mechanism for the ultrasonic assisted absorption has also been discussed. Based on the results, the mass transfer coefficient has increased with the increasing of ultrasonic power. It means that, the presence of streaming effect and the formation of liquid fountain is more favorable under high frequency ultrasonic irradiation for the absorption process. Therefore, high frequency ultrasonic irradiation is suggested to be one of the potential alternatives for the gas separation process with its promising absorption enhancement and compact design. PMID:27245970

  18. High frequency ultrasonic-assisted CO2 absorption in a high pressure water batch system.

    PubMed

    Tay, W H; Lau, K K; Shariff, A M

    2016-11-01

    Physical absorption process is always nullified by the presence of cavitation under low frequency ultrasonic irradiation. In the present study, high frequency ultrasonic of 1.7MHz was used for the physical absorption of CO2 in a water batch system under elevated pressure. The parameters including ultrasonic power and initial feed pressure for the system have been varied from 0 to 18W and 6 to 41bar, respectively. The mass transfer coefficient has been determined via the dynamic pressure-step method. Besides, the actual ultrasonic power that transmitted to the liquid was measured based on calorimetric method prior to the absorption study. Subsequently, desorption study was conducted as a comparison with the absorption process. The mechanism for the ultrasonic assisted absorption has also been discussed. Based on the results, the mass transfer coefficient has increased with the increasing of ultrasonic power. It means that, the presence of streaming effect and the formation of liquid fountain is more favorable under high frequency ultrasonic irradiation for the absorption process. Therefore, high frequency ultrasonic irradiation is suggested to be one of the potential alternatives for the gas separation process with its promising absorption enhancement and compact design.

  19. Prospective regularization design in prior-image-based reconstruction.

    PubMed

    Dang, Hao; Siewerdsen, Jeffrey H; Stayman, J Webster

    2015-12-21

    Prior-image-based reconstruction (PIBR) methods leveraging patient-specific anatomical information from previous imaging studies and/or sequences have demonstrated dramatic improvements in dose utilization and image quality for low-fidelity data. However, a proper balance of information from the prior images and information from the measurements is required (e.g. through careful tuning of regularization parameters). Inappropriate selection of reconstruction parameters can lead to detrimental effects including false structures and failure to improve image quality. Traditional methods based on heuristics are subject to error and sub-optimal solutions, while exhaustive searches require a large number of computationally intensive image reconstructions. In this work, we propose a novel method that prospectively estimates the optimal amount of prior image information for accurate admission of specific anatomical changes in PIBR without performing full image reconstructions. This method leverages an analytical approximation to the implicitly defined PIBR estimator, and introduces a predictive performance metric leveraging this analytical form and knowledge of a particular presumed anatomical change whose accurate reconstruction is sought. Additionally, since model-based PIBR approaches tend to be space-variant, a spatially varying prior image strength map is proposed to optimally admit changes everywhere in the image (eliminating the need to know change locations a priori). Studies were conducted in both an ellipse phantom and a realistic thorax phantom emulating a lung nodule surveillance scenario. The proposed method demonstrated accurate estimation of the optimal prior image strength while achieving a substantial computational speedup (about a factor of 20) compared to traditional exhaustive search. Moreover, the use of the proposed prior strength map in PIBR demonstrated accurate reconstruction of anatomical changes without foreknowledge of change locations in

  20. Data on NAEP 2011 writing assessment prior computer use.

    PubMed

    Tate, Tamara P; Warschauer, Mark; Abedi, Jamal

    2016-09-01

    This data article contains information based on the 2011 National Assessment of Educational Progress in Writing Restricted-Use Data, available from the National Center for Education Statistics (NCES Pub. No. 2014476). https://nces.ed.gov/nationsreportcard/researchcenter/datatools.aspx. The data include the statistical relationships between survey reports of teachers and students regarding prior use of computers and other technology and writing achievement levels on the 2011 computer-based NAEP writing assessment. This data article accompanies "The Effects of Prior Computer Use on Computer-Based Writing: The 2011 NAEP Writing Assessment" [1]. PMID:27508253

  1. Adaptive allocation for binary outcomes using decreasingly informative priors.

    PubMed

    Sabo, Roy T

    2014-01-01

    A method of outcome-adaptive allocation is presented using Bayes methods, where a natural lead-in is incorporated through the use of informative yet skeptical prior distributions for each treatment group. These prior distributions are modeled on unobserved data in such a way that their influence on the allocation scheme decreases as the trial progresses. Simulation studies show this method to behave comparably to the Bayesian adaptive allocation method described by Thall and Wathen (2007), who incorporate a natural lead-in through sample-size-based exponents.

  2. Prospective regularization design in prior-image-based reconstruction

    NASA Astrophysics Data System (ADS)

    Dang, Hao; Siewerdsen, Jeffrey H.; Webster Stayman, J.

    2015-12-01

    Prior-image-based reconstruction (PIBR) methods leveraging patient-specific anatomical information from previous imaging studies and/or sequences have demonstrated dramatic improvements in dose utilization and image quality for low-fidelity data. However, a proper balance of information from the prior images and information from the measurements is required (e.g. through careful tuning of regularization parameters). Inappropriate selection of reconstruction parameters can lead to detrimental effects including false structures and failure to improve image quality. Traditional methods based on heuristics are subject to error and sub-optimal solutions, while exhaustive searches require a large number of computationally intensive image reconstructions. In this work, we propose a novel method that prospectively estimates the optimal amount of prior image information for accurate admission of specific anatomical changes in PIBR without performing full image reconstructions. This method leverages an analytical approximation to the implicitly defined PIBR estimator, and introduces a predictive performance metric leveraging this analytical form and knowledge of a particular presumed anatomical change whose accurate reconstruction is sought. Additionally, since model-based PIBR approaches tend to be space-variant, a spatially varying prior image strength map is proposed to optimally admit changes everywhere in the image (eliminating the need to know change locations a priori). Studies were conducted in both an ellipse phantom and a realistic thorax phantom emulating a lung nodule surveillance scenario. The proposed method demonstrated accurate estimation of the optimal prior image strength while achieving a substantial computational speedup (about a factor of 20) compared to traditional exhaustive search. Moreover, the use of the proposed prior strength map in PIBR demonstrated accurate reconstruction of anatomical changes without foreknowledge of change locations in

  3. Role of strategies and prior exposure in mental rotation.

    PubMed

    Cherney, Isabelle D; Neff, Nicole L

    2004-06-01

    The purpose of these two studies was to examine sex differences in strategy use and the effect of prior exposure on the performance on Vandenberg and Kuse's 1978 Mental Rotation Test. A total of 152 participants completed the spatial task and self-reported their strategy use. Consistent with previous studies, men outperformed women. Strategy usage did not account for these differences, although guessing did. Previous exposure to the Mental Rotation Test, American College Test scores and frequent computer or video game play predicted performance on the test. These results suggest that prior exposure to spatial tasks may provide cues to improve participants' performance.

  4. ATOMIC AND MOLECULAR PHYSICS: X-ray absorption near the edge structure and X-ray photoelectron spectroscopy studies on pyrite prepared by thermally sulfurizing iron films

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Liu, Ying-Shu; Wang, Bao-Yi; Wei, Long; Kui, Re-Xi; Qian, Hai-Jie

    2009-07-01

    This paper reports how pyrite films were prepared by thermal sulfurization of magnetron sputtered iron films and characterized by x-ray absorption near edge structure spectra and x-ray photoelectron spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation Facility. The band gap of the pyrite agrees well with the optical band gap obtained by a spectrophotometer. The octahedral symmetry of pyrite leads to the splitting of the d orbit into t2g and eg levels. The high spin and low spin states were analysed through the difference of electron exchange interaction and the orbital crystal field. Only when the crystal field splitting is higher than 1.5 eV, the two weak peaks above the white lines can appear, and this was approved by experiments in the present work.

  5. Label-free assay for the detection of glucose mediated by the effects of narrowband absorption on quantum dot photoluminescence

    NASA Astrophysics Data System (ADS)

    Khan, Saara A.; Smith, Gennifer T.; Ellerbee, Audrey K.

    2014-03-01

    We present a novel strategy for label-free detection of glucose based on CdSe/ZnS core/shell quantum dots (QDs). We exploit the concentration-dependent, narrowband absorption of the hexokinase-glucose 6-phosphate dehydrogenase enzymatic assay to selectively filter a 365-nm excitation source, leading to a proportional decrease in the photoluminescence intensity of the QDs. The visible wavelength emission of the QDs enables quantitative readout using standard visible detectors (e.g., CCD). Experimental results show highly linear QD photoluminescence over the clinically relevant glucose concentration range of 1-25mM, in excellent agreement with detection methods demonstrated by others. The method has a demonstrated limit of detection of 3.5μM, also on par with the best proposed methods. A significant advantage of our strategy is the complete elimination of QDs as a consumable. In contrast with other methods of QD-based measurement of glucose, our system does not require the glucose solution to be mixed with the QDs, thereby decreasing its overall cost and making it an ideal strategy for point-of-care detection of glucose in low-resource areas. Furthermore, readout can be accomplished with low-cost, portable detectors such as cellular phones, eliminating the need for expensive and bulky spectrophotometers to output quantitative information. The general strategy we present is useful for other biosensing applications involving chemistries with unique absorption peaks falling within the excitation band of available QDs.

  6. Advanced regenerative absorption refrigeration cycles

    DOEpatents

    Dao, Kim

    1990-01-01

    Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

  7. Carbon Dioxide Absorption Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    2002-01-01

    A carbon dioxide absorption heat pump cycle is disclosed using a high pressure stage and a super-critical cooling stage to provide a non-toxic system. Using carbon dioxide gas as the working fluid in the system, the present invention desorbs the CO2 from an absorbent and cools the gas in the super-critical state to deliver heat thereby. The cooled CO2 gas is then expanded thereby providing cooling and is returned to an absorber for further cycling. Strategic use of heat exchangers can increase the efficiency and performance of the system.

  8. NEUTRON ABSORPTION AND SHIELDING DEVICE

    DOEpatents

    Axelrad, I.R.

    1960-06-21

    A neutron absorption and shielding device is described which is adapted for mounting in a radiation shielding wall surrounding a radioactive area through which instrumentation leads and the like may safely pass without permitting gamma or neutron radiation to pass to the exterior. The shielding device comprises a container having at least one nonrectilinear tube or passageway means extending therethrough, which is adapted to contain instrumentation leads or the like, a layer of a substance capable of absorbing gamma rays, and a solid resinous composition adapted to attenuate fast-moving neutrons and capture slow- moving or thermal neutrons.

  9. Effective absorption in cladding-pumped fibers

    NASA Astrophysics Data System (ADS)

    Zervas, Michalis N.; Marshall, Andy; Kim, Jaesun

    2011-02-01

    We investigate experimentally and theoretically the wavelength dependence of the pump absorption along Yb3+-doped fibers, for cladding-pumped single as well as coupled multimode (GTWaveTM) fibers. We show that significant spectral absorption distortions occur along the length with the 976nm absorption peak affected the most. We have developed a novel theoretical approach, based on coupled mode theory, to explain the observed effects. We have also investigated the mode mixing requirements in order to improve the absorption spectral distribution along the increase the overall absorption efficiency and discuss the implications on fiber laser performance.

  10. 12 CFR 333.101 - Prior consent not required.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... POLICY EXTENSION OF CORPORATE POWERS Interpretations § 333.101 Prior consent not required. (a) The... of the Corporation. (b) An insured State nonmember bank, not exercising trust powers, may act as....S.C. 408A and 530 respectively), Health Savings Accounts established pursuant to the...

  11. 7. Historic American Buildings Survey Photocopy, prior to 1867 WEST ...

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

    7. Historic American Buildings Survey Photocopy, prior to 1867 WEST ELEVATION, CITY HALL Restricted: Permission for use must be obtained in writing from Yale University Library New Haven, Connecticut - New Haven City Hall & Courthouse, Church Street, between Court & Elm Streets, New Haven, New Haven County, CT

  12. Prior Experiences Shaping Family Science Conversations at a Nature Center

    ERIC Educational Resources Information Center

    McClain, Lucy R.; Zimmerman, Heather Toomey

    2014-01-01

    Using families as the analytical focus, this study informs the field of informal science education with a focus on the role of prior experiences in family science conversations during nature walks at an outdoor-based nature center. Through video-based research, the team analyzed 16 families during walks at a nature center. Each family's prior…

  13. 5 CFR 7101.102 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE NATIONAL LABOR RELATIONS BOARD § 7101.102 Prior approval... involve conduct prohibited by statute or Federal regulation, including 5 CFR part 2635. (2) The agency designee may consult with the Designated Agency Ethics Official to ensure that the request for...

  14. 5 CFR 8101.103 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE CONSUMER PRODUCT SAFETY COMMISSION § 8101.103 Prior... written approval from his or her supervisor and the Designated Agency Ethics Official (DAEO) or Alternate..., including 5 CFR part 2635. (c) Notification of action. Employees will be notified in writing of the...

  15. 5 CFR 5001.104 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... referenced in subpart H (“Outside Activities”) of 5 CFR part 2635 (Standards of Ethical Conduct for Employees... STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE INTERSTATE COMMERCE COMMISSION § 5001.104 Prior approval... approval of his or her supervisor and the Designated Agency Ethics Official (DAEO). Requests for...

  16. 5 CFR 7801.102 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Designated Agency Ethics Official (DAEO). Volunteer professional services, however, may be “generally... ETHICAL CONDUCT FOR EMPLOYEES OF THE UNITED STATES COMMISSION ON CIVIL RIGHTS § 7801.102 Prior approval... expected to involve conduct prohibited by statute or Federal regulation, including 5 CFR part 2635....

  17. 5 CFR 8701.102 - Prior approval for outside employment.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE OFFICE OF MANAGEMENT AND BUDGET § 8701.102 Prior approval... Ethics Official (DAEO). Requests for approval shall be forwarded through normal supervisory channels to... employment is not expected to involve conduct prohibited by statute or Federal regulation, including 5...

  18. 29. Prior to 1969 STARBOARD SIDE VIEW WHILE DOCKED AT ...

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

    29. Prior to 1969 STARBOARD SIDE VIEW WHILE DOCKED AT CURTIS BAY YARD, BALTIMORE, MARYLAND. IN YEARS FOLLOWING INSTALLATION OF NEW A-FRAME MAST AND BOOM FOR HOISTING SYSTEM. - U.S. Coast Guard Cutter WHITE SAGE, U.S. Coast Guard 1st District Base, 1 Thames Street, Bristol, Bristol County, RI

  19. Perspectives: Prior Learning Assessment Challenges the Status Quo

    ERIC Educational Resources Information Center

    Boilard, Steve D.

    2011-01-01

    Offering some relief from a raft of reports about declining education attainment and increasing college costs, Anya Kamenetz celebrates Prior Learning Assessment (PLA) for boosting higher education productivity, access, and affordability ("Change," September/October 2011). According to Kamenetz, PLA is transforming higher education by leveraging…

  20. Comparing hard and soft prior bounds in geophysical inverse problems

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1987-01-01

    In linear inversion of a finite-dimensional data vector y to estimate a finite-dimensional prediction vector z, prior information about X sub E is essential if y is to supply useful limits for z. The one exception occurs when all the prediction functionals are linear combinations of the data functionals. Two forms of prior information are compared: a soft bound on X sub E is a probability distribution p sub x on X which describeds the observer's opinion about where X sub E is likely to be in X; a hard bound on X sub E is an inequality Q sub x(X sub E, X sub E) is equal to or less than 1, where Q sub x is a positive definite quadratic form on X. A hard bound Q sub x can be softened to many different probability distributions p sub x, but all these p sub x's carry much new information about X sub E which is absent from Q sub x, and some information which contradicts Q sub x. Both stochastic inversion (SI) and Bayesian inference (BI) estimate z from y and a soft prior bound p sub x. If that probability distribution was obtained by softening a hard prior bound Q sub x, rather than by objective statistical inference independent of y, then p sub x contains so much unsupported new information absent from Q sub x that conclusions about z obtained with SI or BI would seen to be suspect.