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Sample records for absorption coefficient mac

  1. Absorption Coefficient of Alkaline Earth Halides.

    DTIC Science & Technology

    1980-04-01

    levels . As a natural consequence, the magnitude of the absorption coefficient is the key parameter in selecting laser window materials. Over the past...of as can be achieved through improved crystal growing techniques and surface polishing. 2.5. Urbach’s Rule A central question for the development of...high absorption levels , inaccuracies progressively increasing with decreasing absorption level , a natural consequence of decreasing in instrumental

  2. Absorption coefficient instrument for turbid natural waters.

    PubMed

    Friedman, E; Poole, L; Cherdak, A; Houghton, W

    1980-05-15

    An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water. The design incorporates methods for compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in background light level. When used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  3. Optical absorption coefficients of pure water

    NASA Astrophysics Data System (ADS)

    Lu, Zheng; Zhao, Xianzhen; Fry, Edward S.

    2002-10-01

    The integrating cavity absorption meter(ICAM), which is independent of scattering effect, is used to measure the absolute values of small optical absorption coefficients of liquid. A modified ICAM is being used to measure the absorption of water in the wavelength range 300 to 700 nm. The ultrapure water produced by a two-stages water purification system reaches Type I quality. This is equal to or better than ASTM,CAP and NCCLS water quality standards. To avoid the fact that dissolved oxygen absorbs ultraviolet light due to the photochemical effect, the water sample is delivered through a nitrogen sealed system which will prevent the sample from contacting with oxygen. A compassion of our absorption spectrum with other existing data is given.

  4. Absorption coefficient instrument for turbid natural waters

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-05-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  5. Absorption coefficient instrument for turbid natural waters

    NASA Technical Reports Server (NTRS)

    Friedman, E.; Cherdak, A.; Poole, L.; Houghton, W.

    1980-01-01

    The paper presents an instrument that directly measures multispectral absorption coefficient of turbid natural water. Attention is given to the design, which is shown to incorporate methods for the compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in the background light level. In addition, when used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Finally, it is reported that systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.

  6. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  7. Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.

    2007-12-01

    aerosol Angstrom absorption exponents by linear regression over the entire UV-visible spectral range. These results are compared to results obtained from the absorbance measurements obtained in the field. The differences in calculated Angstrom absorption exponents between the field and laboratory measurements are attributed partly to the differences in time resolution of the sample collection resulting in heavier particle pileup on the filter surface of the 12-hour samples. Some differences in calculated results can also be attributed to the presence of narrow band absorbers below 400 nm that do not fall in the wavelengths covered by the 7 wavelengths of the aethalometer. 1. Marley, N.A., J.S. Gaffney, J.C. Baird, C.A. Blazer, P.J. Drayton, and J.E. Frederick, "The determination of scattering and absorption coefficients of size-fractionated aerosols for radiative transfer calculations." Aerosol Sci. Technol., 34, 535-549, (2001). This work was conducted as part of the Department of Energy's Atmospheric Science Program as part of the Megacity Aerosol Experiment - Mexico City during MILAGRO. This research was supported by the Office of Science (BER), U.S. Department of Energy Grant No. DE-FG02-07ER64329. We also wish to thank Mexican Scientists and students for their assistance from the Instituto Mexicano de Petroleo (IMP) and CENICA.

  8. Determination of optical absorption coefficient with focusing photoacoustic imaging.

    PubMed

    Li, Zhifang; Li, Hui; Zeng, Zhiping; Xie, Wenming; Chen, Wei R

    2012-06-01

    Absorption coefficient of biological tissue is an important factor for photothermal therapy and photoacoustic imaging. However, its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique to quantify the target optical absorption coefficient. It utilizes the ratio of the amplitude of the peak signal from the top boundary of the target to that from the bottom boundary based on wavelet transform. This method is self-calibrating. Factors, such as absolute optical fluence, ultrasound parameters, and Grüneisen parameter, can be canceled by dividing the amplitudes of the two peaks. To demonstrate this method, we quantified the optical absorption coefficient of a target with various concentrations of an absorbing dye. This method is particularly useful to provide accurate absorption coefficient for predicting the outcomes of photothermal interaction for cancer treatment with absorption enhancement.

  9. Effect of applied mechanical stress on absorption coefficient of compounds

    SciTech Connect

    Gupta, Manoj Kumar; Singh, Gurinderjeet; Dhaliwal, A. S.; Kahlon, K. S.

    2015-08-28

    The absorption coefficient of given materials is the parameter required for the basic information. The measurement of absorption coefficient of compounds Al{sub 2}O{sub 3}, CaCO{sub 3}, ZnO{sub 2}, SmO{sub 2} and PbO has been taken at different incident photon energies 26, 59.54, 112, 1173, 1332keV. The studies involve the measurements of absorption coefficient of the self supporting samples prepared under different mechanical stress. This mechanical stress is render in terms of pressure up to 0-6 ton by using hydraulic press. Measurements shows that absorption coefficient of a material is directly proportional to applied mechanical stress on it up to some extent then become independent. Experimentally measured results are in fairly good agreement with in theoretical values obtained from WinXCOM.

  10. [Experimental determination of the absorption coefficients of biological tissues].

    PubMed

    Kovtun, A V; Kondrat'ev, V S; Terekhov, D V

    1980-01-01

    Procedure is presented for studying the coefficient of biological tissue absorption of radiation with the wavelength lambda = 1.06 mkm. The absorption coefficient is determined by the temperature values of biological tissue experimentally measured with thermopairs. The coherent radiation current falls on the surface of biological tissue. A mathematical model is formulated for biological tissue heating with radiation. Solution of Furier equation obtained by means of Green function is given. Using the relationship found, the energy absorbed by the biological tissue was calculated and the absorption coefficient of radiation with lambda - 1.06 mkm was determined. The results were analysed and the error of the obtained values of absorption coefficients of biological tissues under study were determined.

  11. Continuum Absorption Coefficient of Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.

    1979-01-01

    The rate of heat transfer to the heat shield of a Jupiter probe has been estimated to be one order of magnitude higher than any previously experienced in an outer space exploration program. More than one-third of this heat load is due to an emission of continuum radiation from atoms and ions. The existing computer code for calculating the continuum contribution to the total load utilizes a modified version of Biberman's approximate method. The continuum radiation absorption cross sections of a C - H - O - N ablation system were examined in detail. The present computer code was evaluated and updated by being compared with available exact and approximate calculations and correlations of experimental data. A detailed calculation procedure, which can be applied to other atomic species, is presented. The approximate correlations can be made to agree with the available exact and experimental data.

  12. Prediction of absorption coefficients by pulsed laser induced photoacoustic measurements.

    PubMed

    Priya, Mallika; Satish Rao, B S; Ray, Satadru; Mahato, K K

    2014-06-05

    In the current study, a pulsed laser induced photoacoustic spectroscopy setup was designed and developed, aiming its application in clinical diagnostics. The setup was optimized with carbon black samples in water and with various tryptophan concentrations at 281nm excitations. The sensitivity of the setup was estimated by determining minimum detectable concentration of tryptophan in water at the same excitation, and was found to be 0.035mM. The photoacoustic experiments were also performed with various tryptophan concentrations at 281nm excitation for predicting optical absorption coefficients in them and for comparing the outcomes with the spectrophotometrically-determined absorption coefficients for the same samples. Absorption coefficients for a few serum samples, obtained from some healthy female volunteers, were also determined through photoacoustic and spectrophotometric measurements at the same excitations, which showed good agreement between them, indicating its clinical implications.

  13. NUMERICAL CALCULATION OF MAGNETOBREMSSTRAHLUNG EMISSION AND ABSORPTION COEFFICIENTS

    SciTech Connect

    Leung, Po Kin; Gammie, Charles F.; Noble, Scott C. E-mail: gammie@illinois.edu

    2011-08-10

    Magnetobremsstrahlung (MBS) emission and absorption play a role in many astronomical systems. We describe a general numerical scheme for evaluating MBS emission and absorption coefficients for both polarized and unpolarized light in a plasma with a general distribution function. Along the way we provide an accurate scheme for evaluating Bessel functions of high order. We use our scheme to evaluate the accuracy of earlier fitting formulae and approximations. We also provide an accurate fitting formula for mildly relativistic (kT/(m{sub e}c{sup 2}) {approx}> 0.5) thermal electron emission (and therefore absorption). Our scheme is too slow, at present, for direct use in radiative transfer calculations but will be useful for anyone seeking to fit emission or absorption coefficients in a particular regime.

  14. Methane Absorption Coefficients for the Jovian Planets and Titan

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich; Tomasko, M. G.

    2009-09-01

    We combined 11 data sets of methane transmission measurements within 0.4-5.5 micrometer wavelength in order to better understand the variation of methane absorption with temperature and pressure for conditions in the atmospheres of the Jovian planets and Titan. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere (Tomasko et al. 2008, PSS 56, 624). We present the data with a refined analysis. The last data set consists of Hubble Space Telescope images of Jupiter taken in 2005 and 2007 as Ganymede started to be occulted by Jupiter. Using Ganymede as a light source, we probed Jupiter's stratosphere with large methane pathlengths. Below 1000 nm wavelength, we find methane absorption coefficients generally similar to those by Karkoschka (1998, Icarus 133, 134). We added descriptions of temperature and pressure dependence, which are typically small in this wavelength range. Data in this wavelength range are consistent with each other, except between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the Jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data are consistent with Irwin's model of the pressure dependence of methane absorption. However, when large extrapolations were needed, such as from laboratory data above 200 K to Titan's temperatures near 80 K, Irwin's model of temperature dependence predicts absorption coefficients up to 100 times lower than measured by Huygens. We combined Irwin's and Huygens' data to obtain more reliable methane absorption coefficients for the temperatures in the atmospheres of the Jovian planets and Titan. This research was supported by NASA grants NAG5-12014 and NNX08AE74G.

  15. Vapor-Phase Infrared Absorptivity Coefficient of HN1

    DTIC Science & Technology

    2013-08-01

    infrared spectrometer GC gas chromatography HD sulfur mustard HeNe helium–neon (laser) HgCdTe mercury–cadmium–telluride detector HN1, HN2, HN3...coefficient of the compound. 15. SUBJECT TERMS Vapor phase Saturator cell Infrared (IR) HN1 Vapor pressure Nitrogen mustard Vesicant...9 1 VAPOR-PHASE INFRARED ABSORPTIVITY COEFFICIENT OF HN1 1. INTRODUCTION The nitrogen mustards (HN1, HN2, and HN3) are similar to

  16. Ozone absorption coefficients' role in Dobson instrument ozone measurement accuracy

    NASA Astrophysics Data System (ADS)

    Basher, R. E.

    1982-11-01

    The differences of 10% or more between the laboratory measurements of UV absorption coefficients by different investigators indicate accuracies that are quite inadequate for current needs in the measurement of atmospheric ozone. The standard band-integrated set of coefficients now used with the Dobson instrument are mutually consistent to about 2%, but their absolute accuracy is still in question. The accurate calculation of band-integrated coefficients must take account of their dependence on source spectral irradiance, atmospheric spectral transmittance, mean ozone temperature, and instrument spectral transmittance. A careful examination shows that Komhyr's (1980) case for an error of about +5% in the standard Dobson AD ozone estimation is subject to large uncertainties and certain lacks of independence. The obvious solution to this accuracy problem lies in better laboratory measurements of ozone absorption.

  17. Mean absorption coefficients of He/Ar/N2/(C1-x-y , Ni x , Co y ) thermal plasmas for CNT synthesis

    NASA Astrophysics Data System (ADS)

    Salem, D.; Hannachi, R.; Cressault, Y.; Teulet, Ph; Béji, L.

    2017-01-01

    In this paper, we present the mean absorption coefficients (MACs) calculated for plasma mixtures of argon-helium-nitrogen-carbon-nickel-cobalt at 60 kPa and in a temperature range from 1 kK to 20 kK. These coefficients have been computed under the assumption of a local thermodynamic equilibrium (LTE), isothermal plasma, including atomic and molecular continuum, molecular bands and lines radiation splitted into nine spectral intervals. The results show that the continuum absorption coefficients strongly depend on photodissociation and photoionization processes of the molecular species N2, CN and C2, with a significant effect on photodetachment processes of C- in a frequency interval lower than 1  ×  1015 Hz and for low temperature (<6 kK). While at high temperature, the main contribution in continuum absorption coefficient comes from radiative recombination processes except in the infrared region (<0.5  ×  1015 Hz) where the inverse bremsstrahlung represents the most important component in continuum processes for all temperature values. On the other hand, the calculation of MAC shows that the role of molecular continuum, molecular bands and line absorption of the neutral catalysis species Ni/Co are only important in a small range of temperature and in a few spectral bands located in visible and infrared regions, while at high temperature and in UV and visible regions, the foremost contributions to MAC come from atomic continuum and line absorption.

  18. Impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data.

    PubMed

    Li, Xiaoqi; Jiang, Huabei

    2013-02-21

    We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data-up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT.

  19. Field testing of sound absorption coefficients in a classroom

    NASA Astrophysics Data System (ADS)

    Pettyjohn, Steve

    2005-09-01

    Formal procedures for determining the sound absorption coefficients of materials installed in the field do not exist. However, the U.S. Air Force requested such tests to prove that the sound-absorbing material used in classrooms at Beale AFB in Marysville, CA, met the specified NRC of 0.80. They permitted the use of two layers of 0.5-in. fiberboard or 1-in.-thick fiberglass panels to meet the specified NRC rating. Post-construction tests showed reverberation times longer than expected. Unrealistic sound-absorption coefficients for room finish materials had to be used with the Sabine equation to achieve agreement between the measured and predicted reverberation time. By employing the Fitzroy equation and generally published absorption coefficients for ceiling tile, carpet, and fiberboard, the model provided excellent agreement with the measured reverberation times. The NRC of the fiberboard was computed to be 0.35, agreeing with published data. Since this did not meet project specifications, the Fitzroy model was used to learn the type and quantity of material needed to meet design goals. Follow-up tests showed good agreement between the predicted and measured reverberation times with material added, and project specifications were met. Results are also compared with the requirements of ANSI 12.60.

  20. NitroMAC: An instrument for the measurement of HONO and intercomparison with a long-path absorption photometer.

    PubMed

    Afif, Charbel; Jambert, Corinne; Michoud, Vincent; Colomb, Aurélie; Eyglunent, Gregory; Borbon, Agnès; Daële, Véronique; Doussin, Jean-François; Perros, Pascal

    2016-02-01

    NitroMAC (French acronym for continuous atmospheric measurements of nitrogenous compounds) is an instrument which has been developed for the semi-continuous measurement of atmospheric nitrous acid (HONO). This instrument relies on wet chemical sampling and detection using high performance liquid chromatography (HPLC)-visible absorption at 540 nm. Sampling proceeds by dissolution of gaseous HONO in a phosphate buffer solution followed by derivatization with sulfanilamide/N-(1-naphthyl)-ethylenediamine. The performance of this instrument was found to be as follows: a detection limit of around 3 ppt with measurement uncertainty of 10% over an analysis time of 10 min. Intercomparison was made between the instrument and a long-path absorption photometer (LOPAP) during two experiments in different environments. First, air was sampled in a smog chamber with concentrations up to 18 ppb of nitrous acid. NitroMAC and LOPAP measurements showed very good agreement. Then, in a second experiment, ambient air with HONO concentrations below 250 ppt was sampled. While NitroMAC showed its capability of measuring HONO in moderate and highly polluted environments, the intercomparison results in ambient air highlighted that corrections must be made for minor interferences when low concentrations are measured.

  1. Optimization of the acoustic absorption coefficients of certain functional absorbents

    NASA Technical Reports Server (NTRS)

    Pocsa, V.; Biborosch, L.; Veres, A.; Halpert, E.; Lorian, R.; Botos, T.

    1974-01-01

    The sound absorption coefficients of some functional absorbents (mineral wool plates) are determined by the reverberation chamber method. The influence of the angle of inclination of the sound absorbing material with respect to the surface to be treated is analyzed as well as the influence of the covering index, defined as the ratio of the designed area of a plate and the area of the treated surface belonging to another plate. As compared with the conventional method of applying sound-absorbing plates, the analyzed structures have a higher technological and economical efficiency. The optimum structure corresponds to an angle of inclination of 15 deg and a covering index of 0.8.

  2. A method for monitoring nuclear absorption coefficients of aviation fuels

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Shen, Chih-Ping

    1989-01-01

    A technique for monitoring variability in the nuclear absorption characteristics of aviation fuels has been developed. It is based on a highly collimated low energy gamma radiation source and a sodium iodide counter. The source and the counter assembly are separated by a geometrically well-defined test fuel cell. A computer program for determining the mass attenuation coefficient of the test fuel sample, based on the data acquired for a preset counting period, has been developed and tested on several types of aviation fuel.

  3. Measurement of Acoustic Attenuation and Absorption Coefficients using Thermometry

    NASA Astrophysics Data System (ADS)

    Morris, Hugh; Rivens, Ian; Shaw, Adam; ter Haar, Gail

    2007-05-01

    Accurate knowledge of both the attenuation and the absorption coefficient of tissue are required when planning an optimal high intensity focused ultrasound treatment. A novel technique for simple measurement of this parameters has been developed in which a thin-film thermocouple (TFT) is placed between two layers of tissue of different thicknesses. The sample can be rotated about an axis through the junction of the TFT so that it can be insonated from either side leaving the tissue adjacent to the junction unchanged, but changing the overlying thickness. The attenuation and absorption coefficients can be calculated from the heating curves measured in the two orientations. Experiments have been carried out in both tissue mimicking material (TMM) and in ex vivo liver tissue. Weakly focused transducers, resonant at 1.05 MHz, 2.4 MHz and 3.55 MHz were used at free-field spatial peak intensities of 9-14 W/cm2. The temperature rise was measured as a function of time using a TFT. These thermocouples are not subject to the viscous heating artefact that is common to other thermocouple devices and so are advantageous for this purpose. Alignment was achieved with a 3D automated gantry system, which was controlled with specialised software. Timing and data acquisition were also controlled with this software. All experiments were carried out in degassed water. Results for TMM and degassed excised bovine liver are presented.

  4. Measurements of the absorption coefficient of stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ogren, J. A.; Ahlquist, N. C.; Clarke, A. D.; Charlson, R. J.

    1981-01-01

    The absorption coefficients of stratospheric aerosols are measured using a variation on the integrating plate method. The technique is based on the decrease in the transparency of a substrate when an absorbing aerosol is deposited on it. A Lambert scatterer is placed behind the substrate to integrate forward scattered light and minimize the effect of scattering on the measurement. The low pressure in the stratosphere is used for the direct impaction of particles onto a narrow strip of opal glass. The eight samples collected had a median value of 4 x 10 to the -9th m with an uncertainty of + or - 5 x 10 to the -9th m. If this absorption is due to graphitic carbon, then its concentration is estimated at about 0.4 ng/cu m, or about 0.25% of the total aerosol mass concentration. Estimates of the aerosol scattering coefficients based on satellite extinction inversions result in an aerosol single-scattering albedo in the range of 0.96-1.0.

  5. Temperature coefficient of resistance and thermal conductivity of Vanadium oxide 'Big Mac' sandwich structure

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, M.; Ilahi, S.; Zia, M. F.; Alduraibi, M.; Debbar, N.; Yacoubi, N.; Ilahi, B.

    2015-07-01

    In this paper, we synthesize and characterize a thin film thermometer structure for infrared microbolometers. The structure is composed of alternating multilayers of Vanadium pentoxide (V2O5), 25 nm, and Vanadium (V), 5 nm, thin films deposited by rf magnetron and dc magnetron sputtering respectively and annealed for 20, 30 and 40 min at 300 °C in Nitrogen (N2) atmosphere. The best achieved temperature coefficient of resistance (TCR) was found to be -2.57%/K for 40 min annealed samples. Moreover, we apply, for the first time, the photo-thermal deflection (PTD) technique for measuring the thermal conductivity of the synthesized thin films. The thermal conductivity of the developed thin films reveals an increase in thermal conductivity from 2 W/m K to 5.8 W/m K for as grown and 40 min annealed samples respectively.

  6. Photon absorption potential coefficient as a tool for materials engineering

    NASA Astrophysics Data System (ADS)

    Akande, Raphael Oluwole; Oyewande, Emmanuel Oluwole

    2016-09-01

    Different atoms achieve ionizations at different energies. Therefore, atoms are characterized by different responses to photon absorption in this study. That means there exists a coefficient for their potential for photon absorption from a photon source. In this study, we consider the manner in which molecular constituents (atoms) absorb photon from a photon source. We observe that there seems to be a common pattern of variation in the absorption of photon among the electrons in all atoms on the periodic table. We assume that the electrons closest to the nucleus (En) and the electrons closest to the outside of the atom (Eo) do not have as much potential for photon absorption as the electrons at the middle of the atom (Em). The explanation we give to this effect is that the En electrons are embedded within the nuclear influence, and similarly, Eo electrons are embedded within the influence of energies outside the atom that there exists a low potential for photon absorption for them. Unlike En and Eo, Em electrons are conditioned, such that there is a quest for balance between being influenced either by the nuclear force or forces external to the atom. Therefore, there exists a higher potential for photon absorption for Em electrons than for En and Eo electrons. The results of our derivations and analysis always produce a bell-shaped curve, instead of an increasing curve as in the ionization energies, for all elements in the periodic table. We obtained a huge data of PAPC for each of the several materials considered. The point at which two or more PAPC values cross one another is termed to be a region of conflicting order of ionization, where all the atoms absorb equal portion of the photon source at the same time. At this point, a greater fraction of the photon source is pumped into the material which could lead to an explosive response from the material. In fact, an unimaginable and unreported phenomenon (in physics) could occur, when two or more PAPCs cross, and

  7. Inference of the microwave absorption coefficient from stray radiation measurements in Wendelstein 7-X

    NASA Astrophysics Data System (ADS)

    Moseev, D.; Laqua, H. P.; Marsen, S.; Marushchenko, N.; Stange, T.; Braune, H.; Gellert, F.; Hirsch, M.; Hoefel, U.; Knauer, J.; Oosterbeek, J. W.; Turkin, Y.; The Wendelstein 7-X Team

    2017-03-01

    The efficiency of electron cyclotron heating is determined by the microwave absorption of the plasma. Good microwave absorption is also crucial for the machine safety. In this paper we present a method of evaluating the microwave absorption coefficient from stray radiation measurements. The discussed method is computationally simple and can be applied potentially in real time. Evolution of the second harmonic extraordinary mode (X2) microwave absorption coefficient in Wendelstein 7-X during the start-up phase is presented, as well as an estimate of the absorption coefficient for the second harmonic ordinary mode (O2) wave.

  8. FTIR-spectrometer-determined absorption coefficients of seven hydrazine fuel gases - Implications for laser remote sensing

    NASA Technical Reports Server (NTRS)

    Molina, L. T.; Grant, W. B.

    1984-01-01

    The absorption spectra of three hydrazines and four of their air-oxidation products were measured in the 9-12-micron spectral region with a Fourier transform infrared (FTIR) spectrometer with a 0.05-kayser resolution to determine absorption coefficients at CO2 and tunable diode laser wavelengths. The measurements agreed well with published CO2 laser determinations for many of the absorption coefficients, except where the published values are thought to be in error. The coefficients were then used to estimate the sensitivity for remote detection of these gases using CO2 and tunable diode lasers in long-path differential absorption measurements.

  9. Dynamic absorption coefficients of CAR and non-CAR resists at EUV

    NASA Astrophysics Data System (ADS)

    Fallica, Roberto; Stowers, Jason K.; Grenville, Andrew; Frommhold, Andreas; Robinson, Alex P. G.; Ekinci, Yasin

    2016-03-01

    The dynamic absorption coefficients of several CAR and non-CAR EUV photoresists are measured experimentally using a specifically developed setup in transmission mode at the XIL beamline of the Swiss Light Source. The absorption coefficient α and the Dill parameters ABC were measured with unprecedented accuracy. In general the α of resists match very closely with the theoretical value calculated from elemental densities and absorption coefficients, whereas exceptions are observed. In addition, through the direct measurements of the absorption coefficients and dose-to-clear values, we introduce a new figure of merit called Chemical Sensitivity to account for all the post-absorption chemical reaction ongoing in the resist, which is also predicts a quantitative clearing volume, and respectively clearing radius, due to the photon absorption in the resist. These parameters may help in deeper insight into the underlying mechanisms of EUV concept of clearing volume and clearing radius are then defined and quantitatively calculated.

  10. Study of the absorption coefficient in layers of a semiconductor laser heterostructure

    SciTech Connect

    Veselov, D A; Pikhtin, N A; Lyutetskiy, A V; Nikolaev, D N; Slipchenko, S O; Sokolova, Z N; Shamakhov, V V; Shashkin, I S; Voronkova, N V; Tarasov, I S

    2015-07-31

    A method of studying the absorption coefficient in layers of semiconductor lasers is proposed. Using lasers based on MOVPE-grown separate-confinement heterostructures with a broadened waveguide, the absorption coefficient is investigated under pulsed current pumping. It is found that when the pump current flows through the laser in question, an additional internal optical absorption arises in the heterostructure layers. It is shown that an increase in the pump current density up to 20 kA cm{sup -2} leads to an increase in absorption up to 2.5 cm{sup -1}. The feasibility of studying free-carrier absorption in the active region is demonstrated. (lasers)

  11. Measurement of the absorption coefficient using the sound-intensity technique

    NASA Technical Reports Server (NTRS)

    Atwal, M.; Bernhard, R.

    1984-01-01

    The possibility of using the sound intensity technique to measure the absorption coefficient of a material is investigated. This technique measures the absorption coefficient by measuring the intensity incident on the sample and the net intensity reflected by the sample. Results obtained by this technique are compared with the standard techniques of measuring the change in the reverberation time and the standing wave ratio in a tube, thereby, calculating the random incident and the normal incident adsorption coefficient.

  12. Mass-specific optical absorption coefficients and imaginary part of the complex refractive indices of mineral dust components measured by a multi-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2015-01-01

    Mass-specific optical absorption coefficients (MACs) and the imaginary part (κ) of the refractive indices of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at the wavelengths of 1064, 532, 355 and 266 nm. The MAC values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. Values of κ were calculated from the measured and particle-loss-corrected data by using a Mie-theory-based retrieval algorithm. The determined values could be used for comparisons with calculated wavelength-dependent κ values typically deduced from bulk-phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk-phase measurements.

  13. Absorption Coefficient Imaging by Near-Field Scanning Optical Microscopy in Bacteria

    NASA Astrophysics Data System (ADS)

    de Paula, Ana M.; Chaves, Claudilene R.; Silva, Haroldo B.; Weber, Gerald

    2003-06-01

    We present a method for obtaining a position-dependent absorption coefficient from near-field scanning optical transmission microscopy. We show that the optical transmission intensity can be combined with the topography, resulting into an absorption coefficient that simplifies the analysis of different materials within a sample. The method is tested with the dye rhodamine 6G, and we show some analysis in biological samples such as bacteria Klebsiella pneumoniae and Pseudomonas aeruginosa . The calculated absorption coefficient images show important details of the bacteria, in particular for P. aeruginosa , in which membrane vesicles are clearly seen.

  14. Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

    1993-01-01

    Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

  15. Absorption coefficient measurements of particle-laden filters using laser heating: Validation with nigrosin

    NASA Astrophysics Data System (ADS)

    Presser, Cary

    2012-05-01

    A laser-heating technique, referred as the laser-driven thermal reactor, was used in conjunction with laser transmissivity measurements to determine the absorption coefficient of particle-laden substrates (e.g., quartz-fiber filters). The novelty of this approach is that it analyzes a wide variety of specific samples (not just filtered samples) and overcomes measurement issues (e.g., absorption enhancement) associated with other filter-based particle absorption techniques. The absorption coefficient was determined for nigrosin-laden, quartz-fiber filters and the effect of the filter on the absorption measurements was estimated when compared to the isolated nigrosin results. The isolated nigrosin absorption coefficient compared favorably with Lorenz-Mie calculations for an idealized polydispersion of spherical particles (based on a measured nigronsin/de-ionized water suspension size distribution) dispersed throughout a volume equivalent to that of the nigrosin-laden filter. To validate the approach, the absorption coefficient of a nigrosin/de-ionized water suspension was in good agreement with results obtained from an ultraviolet/visible spectrometer. In addition, the estimated imaginary part of the refractive index from the Lorenz-Mie calculations compared well with literature values and was used to estimate the absorption coefficient of optically opaque packed nigrosin.

  16. Visible and Near Infrared Absorption Coefficients of Kaolinite and Related Clays.

    DTIC Science & Technology

    propagation of light. This work is intended to provide a quantitative estimate of the absorption coefficient of kaolinite clays by application of a method based on the Kubelka - Munk theory of diffuse reflectance.

  17. A method for determination mass absorption coefficient of gamma rays by Compton scattering.

    PubMed

    El Abd, A

    2014-12-01

    A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.

  18. Satellite retrieval of the absorption coefficient of phytoplankton phycoerythrin pigment: theory and feasibility status.

    PubMed

    Hoge, F E; Wright, C W; Lyon, P E; Swift, R N; Yungel, J K

    1999-12-20

    Oceanic radiance model inversion methods are used to develop a comprehensive algorithm for retrieval of the absorption coefficients of phycourobilin (PUB) pigment, type I phycoerythrobilin (PEB) pigment rich in PUB, and type II PEB deficient in PUB pigment (together with the usual "big three" inherent optical properties: the total backscattering coefficient and the absorption coefficients of chromophoric dissolved organic matter (CDOM)-detritus and phytoplankton). This fully modeled inversion algorithm is then simplified to yield a hybrid modeled-unmodeled inversion algorithm in which the phycoerythrin (PE) absorption coefficient is retrieved as unmodeled 488-nm absorption (which exceeds the modeled phytoplankton and the CDOM-detritus absorption coefficients). Each algorithm was applied to water-leaving radiances, but only hybrid modeled-unmodeled inversions yielded viable retrievals of the PE absorption coefficient. Validation of the PE absorption coefficient retrieval was achieved by relative comparison with airborne laser-induced PEB fluorescence. The modeled-unmodeled retrieval of four inherent optical properties by direct matrix inversion is rapid and well conditioned, but the accuracy is strongly limited by the accuracy of the three principal inherent optical property models across all four spectral bands. Several research areas are identified to enhance the radiance-model-based retrievals: (a) improved PEB and PUB absorption coefficient models, (b) PE spectral shifts induced by PUB chromophore substitution at chromophore binding sites, (c) specific absorption-sensitive phytoplankton absorption modeling, (d) total constituent backscattering modeling, (e) unmodeled carotinoid and phycocyanin absorption that are not now accounted for in the chlorophyll-dominated phytoplankton absorption coefficient model, and (f) iterative inversion techniques to solve for six constituents with only five radiances. Although considerable progress has been made toward the

  19. Experiment to Determine the Absorption Coefficient of Gamma Rays as a Function of Energy.

    ERIC Educational Resources Information Center

    Ouseph, P. J.; And Others

    1982-01-01

    Simpler than x-ray diffractometer experiments, the experiment described illustrates certain concepts regarding the interaction of electromagnetic rays with matter such as the exponential decrease in the intensity with absorber thickness, variation of the coefficient of absorption with energy, and the effect of the K-absorption edge on the…

  20. Determination of absorption coefficients in AlInP lattice matched to GaAs

    NASA Astrophysics Data System (ADS)

    Cheong, J. S.; Ng, J. S.; Krysa, A. B.; Ong, J. S. L.; David, J. P. R.

    2015-10-01

    The absorption properties of Al0.52In0.48P have been investigated near the fundamental absorption edge by measuring the photocurrent as a function of wavelength in a series of PIN and NIP diodes. Modelling of the photocurrent in these structures enables the absorption coefficients to be determined accurately over a wide dynamic range, which allows the direct and indirect band-gap to be determined.

  1. Absorption and Scattering Coefficients: A Biophysical-Chemistry Experiment Using Reflectance Spectroscopy

    ERIC Educational Resources Information Center

    Cordon, Gabriela B.; Lagorio, M. Gabriela

    2007-01-01

    A biophysical-chemistry experiment, based on the reflectance spectroscopy for calculating the absorption and scattering coefficients of leaves is described. The results show that different plants species exhibit different values for both the coefficients because of their different pigment composition.

  2. Tunable diode laser measurements of HO2NO2 absorption coefficients near 12.5 microns

    NASA Technical Reports Server (NTRS)

    May, R. D.; Molina, L. T.; Webster, C. R.

    1988-01-01

    A tunable diode laser spectrometer has been used to measure absorption coefficients of peroxynitric acid (HO2NO2) near the 803/cm Q branch. HO2NO2 concentrations in a low-pressure flowing gas mixture were determined from chemical titration procedures and UV absorption spectroscopy. The diode laser measured absorption coefficients, at a spectral resolution of better than 0.001/cm, are about 10 percent larger than previous Fourier transform infrared measurements made at a spectral resolution of 0.06/cm.

  3. Determination of molar absorption coefficients of organic compounds adsorbed in porous media.

    PubMed

    Ciani, Andrea; Goss, Kai-Uwe; Schwarzenbach, René P

    2005-12-01

    The kinetics of direct photochemical transformations of organic compounds in light absorbing and scattering media has been sparsely investigated. This is mostly due to the experimental difficulties to assess the major parameters: light intensity in porous media, the reaction quantum yield and the molar absorption coefficient of the adsorbed compound, epsilon(i) (lambda). Here, we propose a method for the determination of the molar absorption coefficient of compounds adsorbed to air-dry surfaces using the Kubelka-Munk model for the description of radiative transfer. To illustrate the method, the molar absorption coefficients of three compounds, i.e. 4-nitroanisole (PNA), the herbicide trifluralin and the flame retardant decabromodiphenyl ether (DecaBDE), were determined on air-dry kaolinite. The measured diffuse reflectance spectra were evaluated with the Kubelka-Munk model and with previously determined Kubelka-Munk absorption and scattering coefficients (k and s), for kaolinite. For all compounds the maximum absorption band was found to be red shifted and the corresponding epsilon(i) (lambda) values were significantly greater than those determined in solvents. Together with the absorption and scattering coefficient of the medium, the measured epsilon(i) (lambda) can be used to determine the quantum yield of the photochemical reaction in this medium from experimentally determined reaction kinetics.

  4. [Extracting THz absorption coefficient spectrum based on accurate determination of sample thickness].

    PubMed

    Li, Zhi; Zhang, Zhao-hui; Zhao, Xiao-yan; Su, Hai-xia; Yan, Fang

    2012-04-01

    Extracting absorption spectrum in THz band is one of the important aspects in THz applications. Sample's absorption coefficient has a complex nonlinear relationship with its thickness. However, as it is not convenient to measure the thickness directly, absorption spectrum is usually determined incorrectly. Based on the method proposed by Duvillaret which was used to precisely determine the thickness of LiNbO3, the approach to measuring the absorption coefficient spectra of glutamine and histidine in frequency range from 0.3 to 2.6 THz(1 THz = 10(12) Hz) was improved in this paper. In order to validate the correctness of this absorption spectrum, we designed a series of experiments to compare the linearity of absorption coefficient belonging to one kind amino acid in different concentrations. The results indicate that as agreed by Lambert-Beer's Law, absorption coefficient spectrum of amino acid from the improved algorithm performs better linearity with its concentration than that from the common algorithm, which can be the basis of quantitative analysis in further researches.

  5. Implications of New Methane Absorption Coefficients on Uranus Vertical Structure Derived from Near-IR Spectra

    NASA Astrophysics Data System (ADS)

    Fry, Patrick M.; Sromovsky, L. A.

    2009-09-01

    Using new methane absorption coefficients from Karkoschka and Tomasko (2009, submitted to Icarus, "Methane Absorption Coefficients for the Jovian Planets from Laboratory, Huygens, and HST Data"), we fit Uranus near-IR spectra previously analyzed in Sromovsky et al. (2006, Icarus 182, 577-593, Fink and Larson, 1979 J- and H-band), Sromovsky and Fry (2008, Icarus 193, 252-266, 2006 NIRC2 J- and H-band, 2006 SpeX) using Irwin et al. (2006, Icarus 181, 309-319) methane absorption coefficients. Because the new absorption coefficients usually result in higher opacities at the low temperatures seen in Uranus' upper troposphere, our previously derived cloud altitudes are expected to generally rise to higher altitudes. For example, using Lindal et al. (1987, JGR 92, 14987-15001) model D temperature and methane abundance profiles, we are better able to fit the J-band 43-deg. south bright band with the new coefficients (chi-square=205, vs. 315 for Irwin), with the pressure of the upper tropospheric cloud decreasing to 1.6 bars (from 2.4 bars using Irwin coefficients). Improvements in fitting H-band spectra from the same latitude are not as readily obtained. Derived upper tropospheric cloud pressures are very similar using the two absorption datasets (1.6-1.7 bars), but the character of the fits differs. New Karkoschka and Tomasko coefficients better fit some details in the 1.5-1.58 micron region, but Irwin fits the broad absorption band wing at 1.61-1.62 microns better, and the fit chi-square values are similar (K&T: 243, Irwin: 220). Results for a higher methane concentration (Lindal et al. model F) were similar. Whether the new coefficients will simply raise derived altitudes across the planet or will result in fundamental changes in structure is as yet unclear. This work was suported by NASA planetary astronomy and planetary atmospheres programs.

  6. Nonlinear absorption coefficient of pulsed laser deposited MgZnO thin film

    SciTech Connect

    Agrawal, Arpana Dar, Tanveer A.; Solanki, Ravi; Sen, Pratima; Phase, D. M.

    2015-06-24

    We report the imaginary part of 3{sup rd} order nonlinear susceptibility and the nonlinear absorption coefficient of Mg doped ZnO thin film using standard Z-scan technique. The origin of nonlinear absorption is attributed to the two photon absorption followed by the free carrier absorption because of the presence of oxygen vacancy defects. We have also confirmed the experimental results with the theoretical results obtained by considering the steady state response of a two level atom with the monochromatic field models.

  7. Assessing Absorption Coefficient of Hemoglobin in the Breast Phantom Using Near-Infrared Spectroscopy

    PubMed Central

    Mehnati, Parinaz; Jafari Tirtash, Maede; Zakerhamidi, Mohammad Sadegh; Mehnati, Parisa

    2016-01-01

    Background Blood concentrations and oxygen saturation levels are important biomarkers for breast cancer diagnosis. Objectives In this study, the absorption coefficient of hemoglobin (Hb) was used to distinguish between normal and abnormal breast tissue. Materials and Methods A near-infrared source (637 nm) was transmitted from major and minor vessels of a breast phantom containing 2×, 4× concentrations of oxy- and deoxy-Hb. The absorption coefficients were determined from spectrometer (SM) and powermeter (PM) data. Results The absorption coefficients were 0.075 ± 0.026 cm-1 for oxygenated Hb (normal) in major vessels and 0.141 ± 0.023 cm-1 at 4× concentration (abnormal) with SM, whereas the breast absorption coefficients were 0.099 ± 0.017 cm-1 for oxygenated Hb (normal) in minor vessels and 0.171 ± 0.005 cm-1 at 4× concentrations with SM. A comparison of the data obtained using a SM and a PM was not significant statistically. Conclusion The study of the absorption coefficient data of different concentrations of Hb in normal and abnormal breasts via the diffusion of near-infrared light is a valuable method and has the potential to aid in early detection of breast abnormalities with SM and PM in major and minor vessels. PMID:27895869

  8. Evaluation of ammonia absorption coefficients by photoacoustic spectroscopy for detection of ammonia levels in human breath

    NASA Astrophysics Data System (ADS)

    Dumitras, D. C.; Dutu, D. C.; Matei, C.; Cernat, R.; Banita, S.; Patachia, M.; Bratu, A. M.; Petrus, M.; Popa, C.

    2011-04-01

    Photoacoustic spectroscopy represents a powerful technique for measuring extremely low absorptions independent of the path length and offers a degree of parameter control that cannot be attained by other methods. We report precise measurements of the ammonia absorption coefficients at the CO2 laser wavelengths by using a photoacoustic (PA) cell in an extracavity configuration and we compare our results with other values reported in the literature. Ammonia presents a clear fingerprint spectrum and high absorption strengths in the CO2 wavelengths region. Because more than 250 molecular gases of environmental concern for atmospheric, industrial, medical, military, and scientific spheres exhibit strong absorption bands in the region 9.2-10.8 μm, we have chosen a frequency tunable CO2 laser. In the present work, ammonia absorption coefficients were measured at both branches of the CO2 laser lines by using a calibrated mixture of 10 ppm NH3 in N2. We found the maximum absorption in the 9 μm region, at 9R(30) line of the CO2 laser. One of the applications based on the ammonia absorption coefficients is used to measure the ammonia levels in exhaled human breath. This can be used to determine the exact time necessary at every session for an optimal degree of dialysis at patients with end-stage renal disease.

  9. Minority carrier diffusion lengths and absorption coefficients in silicon sheet material

    NASA Technical Reports Server (NTRS)

    Dumas, K. A.; Swimm, R. T.

    1980-01-01

    Most of the methods which have been developed for the measurement of the minority carrier diffusion length of silicon wafers require that the material have either a Schottky or an ohmic contact. The surface photovoltage (SPV) technique is an exception. The SPV technique could, therefore, become a valuable diagnostic tool in connection with current efforts to develop low-cost processes for the production of solar cells. The technique depends on a knowledge of the optical absorption coefficient. The considered investigation is concerned with a reevaluation of the absorption coefficient as a function of silicon processing. A comparison of absorption coefficient values showed these values to be relatively consistent from sample to sample, and independent of the sample growth method.

  10. Determination of the Absorption Coefficient and Cloudiness Multiplicity Attenuation During the Gamma-Radiation Passage

    NASA Astrophysics Data System (ADS)

    Orlova, K. N.; Borovikov, I. F.; Gaidamak, M. A.

    2016-08-01

    The paper presents background value equivalent dose of gamma-radiation investigation in different weather: clear cloudy and overcast. The change of the dose rate of gamma radiation, depending on the weather and the ability cloudiness to shield gamma rays is shown. A new method for eliminating the consequences of accidents at nuclear power plants or plants using radioactive elements is proposed. A calculation method of cloudiness coefficient absorption and cloudiness gamma-radiation multiplicity attenuation is developed. The gamma- radiation multiplicity attenuation and the absorption coefficient of gamma radiation were calculated.

  11. A numerical study of a method for measuring the effective in situ sound absorption coefficient.

    PubMed

    Kuipers, Erwin R; Wijnant, Ysbrand H; de Boer, André

    2012-09-01

    The accuracy of a method [Wijnant et al., Proc. of ISMA 31, Leuven, Belgium (2010), Vol. 31] for measurement of the effective area-averaged in situ sound absorption coefficient is investigated. Based on a local plane wave assumption, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situ sound absorption coefficient in complex sound fields.

  12. Measurement of optical absorption coefficient of bio-tissue at 532nm wavelength

    NASA Astrophysics Data System (ADS)

    Huang, Chuyun; Li, Zhengjia; Yao, Yucheng; He, Yanyan

    2007-05-01

    Laser technology has succeeded in medical application. High power 532nm laser has applied in prostate ablation and other clinic application. To understand optical property of bio-tissue at 532nm wavelength, a method of monitoring surface temperature was used to measure absorption coefficient of gall-stone, porcine liver and canine prostate. The absorption coefficient of gall-stone is about 62cm -1 at 532nm wavelength, and those of porcine liver and canine prostate are about 13cm -1 and 5.4cm -1, respectively. These results help to understand the optical property of bio-tissue and offer theoretic reference for optical dosimetry in clinic application.

  13. In vivo light fluence correction for determination of tissue absorption coefficient using Multispectral Optoacoustic Tomography

    NASA Astrophysics Data System (ADS)

    Brochu, Frederic M.; Joseph, James; Tomaszewski, Michal R.; Bohndiek, Sarah E.

    2016-03-01

    Optoacoustic Tomography is a fast developing imaging modality, combining the high resolution and penetration depth of ultrasound detection with the high contrast available from optical absorption in tissue. The spectral profile of near infrared excitation light used in optoacoustic tomography instruments is modified by absorption and scattering as it propagates deep into biological tissue. The resulting images therefore provide only qualitative insight into the distribution of tissue chromophores. Knowledge of the spectral profile of excitation light across the mouse is needed for accurate determination of the absorption coefficient in vivo. Under the conditions of constant Grueneisen parameter and accurate knowledge of the light fluence, a linear relationship should exist between the initial optoacoustic pressure amplitude and the tissue absorption coefficient. Using data from a commercial optoacoustic tomography system, we implemented an iterative optimization based on the σ-Eddington approximation to the Radiative Transfer Equation to derive a light fluence map within a given object. We segmented the images based on the positions of phantom inclusions, or mouse organs, and used known scattering coefficients for initialization. Performing the fluence correction in simple phantoms allowed the expected linear relationship between recorded and independently measured absorption coefficients to be retrieved and spectral coloring to be compensated. For in vivo data, the correction resulted in an enhancement of signal intensities in deep tissues. This improved our ability to visualize organs at depth (> 5mm). Future work will aim to perform the optimization without data normalization and explore the need for methodology that enables routine implementation for in vivo imaging.

  14. Dynamic absorption coefficients of chemically amplified resists and nonchemically amplified resists at extreme ultraviolet

    NASA Astrophysics Data System (ADS)

    Fallica, Roberto; Stowers, Jason K.; Grenville, Andrew; Frommhold, Andreas; Robinson, Alex P. G.; Ekinci, Yasin

    2016-07-01

    The dynamic absorption coefficients of several chemically amplified resists (CAR) and non-CAR extreme ultraviolet (EUV) photoresists are measured experimentally using a specifically developed setup in transmission mode at the x-ray interference lithography beamline of the Swiss Light Source. The absorption coefficient α and the Dill parameters ABC were measured with unprecedented accuracy. In general, the α of resists match very closely with the theoretical value calculated from elemental densities and absorption coefficients, whereas exceptions are observed. In addition, through the direct measurements of the absorption coefficients and dose-to-clear values, we introduce a new figure of merit called chemical sensitivity to account for all the postabsorption chemical reaction ongoing in the resist, which also predicts a quantitative clearing volume and clearing radius, due to the photon absorption in the resist. These parameters may help provide deeper insight into the underlying mechanisms of the EUV concepts of clearing volume and clearing radius, which are then defined and quantitatively calculated.

  15. Studies on mass energy-absorption coefficients and effective atomic energy-absorption cross sections for carbohydrates

    NASA Astrophysics Data System (ADS)

    Ladhaf, Bibifatima M.; Pawar, Pravina P.

    2015-04-01

    We measured here the mass attenuation coefficients (μ/ρ) of carbohydrates, Esculine (C15H16O9), Sucrose (C12H22O11), Sorbitol (C6H14O6), D-Galactose (C6H12O6), Inositol (C6H12O6), D-Xylose (C5H10O5) covering the energy range from 122 keV up to 1330 keV photon energies by using gamma ray transmission method in a narrow beam good geometry set-up. The gamma-rays were detected using NaI(Tl) scintillation detection system with a resolution of 8.2% at 662 keV. The attenuation coefficient data were then used to obtain the total attenuation cross-section (σtot), molar extinction coefficients (ε), mass-energy absorption coefficients (μen/ρ) and effective (average) atomic energy-absorption cross section (σa,en) of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  16. Determination of Absorption and Scattering Coefficients for Nonhomogeneous Media: II. Experiment.

    DTIC Science & Technology

    prepared from a glass of known absorption coefficient variation. The new model produces an accuracy inprovement up to a factor of 2.5 over the Kubelka ... Munk theory. Off-axis scattering measurements were made with improved instrumentation between 0.33 and 2.7 micrometers. The model was then applied to

  17. Calibration of an integrating sphere for determining the absorption coefficient of scattering suspensions.

    PubMed

    Nelson, N B; Prézelin, B B

    1993-11-20

    Measuring the absolute absorption of suspensions of absorbing particles with unknown scattering characteristics is not possible in conventional spectrophotometers or in integrating spheres that have the sample located outside the sphere. A method for the calibration and use of an integrating sphere with a centrally located sample to measure absolute absorption coefficients of scattering suspensions is presented. Under the tested conditions the integrating sphere used in this study was insensitive to changes in the scattering coefficient of the sample but had a nonlinear response to increasing absorption of the sample, which could be corrected with an empirically derived function. This response was analyzed by using a Monte Carlo simulation, and results indicated that amplification of the absorption signal was primarily due to photons reflected from the sphere surface and the baffle reentering the cuvette. The calibration procedure described here may be generally applicable to spheres of different configurati n. An example of the use of the sphere for determining the absorption and scattering coefficients of marine phytoplankton samples is presented.

  18. Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2014-09-01

    Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

  19. [Development of a photoacoustic spectroscopy system for the measurement of absorption coefficient of atmospheric aerosols].

    PubMed

    Liu, Qiang; Niu, Ming-Sheng; Wang, Gui-Shi; Cao, Zhen-Song; Liu, Kun; Chen, Wei-Dong; Gao, Xiao-Ming

    2013-07-01

    In the present paper, the authors focus on the effect of the resonance frequency shift due to the changes in temperature and humidity on the PA signal, present several methods to control the noise derived form gas flow and vibration from the sampling pump. Based on the efforts mentioned above, a detection limit of 1.4 x 10(-8) W x cm(-1) x Hz(-1/2) was achieved for the measurement of atmospheric aerosols absorption coefficient. During the experiments, the PA cell was calibrated with the absorption of standard NO2 gas at 532 nm and the atmospheric aerosols were measured continuously. The measurement results show that the PAS is suitable for the real-time measurement of the absorption coefficient of atmospheric aerosols in their natural suspended state.

  20. Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime.

    PubMed

    Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V

    2012-06-01

    Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.

  1. Light fluence correction for quantitative determination of tissue absorption coefficient using multi-spectral optoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Brochu, Frederic M.; Joseph, James; Tomaszewski, Michal; Bohndiek, Sarah E.

    2015-07-01

    MultiSpectral Optoacoustic Tomography (MSOT) is a fast developing imaging modality, combining the high resolution and penetration depth of ultrasound with the excellent contrast from optical imaging of tissue. Absorption and scattering of the near infrared excitation light modulates the spectral profile of light as it propagates deep into biological tissue, meaning the images obtained provide only qualitative insight into the distribution of tissue chromophores. The goal of this work is to accurately recover the spectral profile of excitation light by modelling light fluence in the data reconstruction, to enable quantitative imaging. We worked with a commercial small animal MSOT scanner and developed our light fluence correction for its' cylindrical geometry. Optoacoustic image reconstruction pinpoints the sources of acoustic waves detected by the transducers and returns the initial pressure amplitude at these points. This pressure is the product of the dimensionless Grüneisen parameter, the absorption coefficient and the light fluence. Under the condition of constant Grüneisen parameter and well modelled light fluence, there is a linear relationship between the initial pressure amplitude measured in the optoacoustic image and the absorption coefficient. We were able to reproduce this linear relationship in different physical regions of an agarose gel phantom containing targets of known optical absorption coefficient, demonstrating that our light fluence model was working. We also demonstrate promising results of light fluence correction effects on in vivo data.

  2. Diffuse reflectance spectroscopy as a tool to measure the absorption coefficient in skin: system calibration.

    PubMed

    Karsten, A E; Singh, A; Karsten, P A; Braun, M W H

    2013-02-01

    An individualised laser skin treatment may enhance the treatment and reduces risks and side-effects. The optical properties (absorption and scattering coefficients) are important parameters in the propagation of laser light in skin tissue. The differences in the melanin content of different skin phototypes influence the absorption of the light. The absorption coefficient at the treatment wavelength for an individual can be determined by diffuse reflectance spectroscopy, using a probe containing seven fibres. Six of the fibres deliver the light to the measurement site and the central fibre collects the diffused reflected light. This is an in vivo technique, offering benefits for near-real-time results. Such a probe, with an effective wavelength band from 450 to 800 nm, was used to calibrate skin-simulating phantoms consisting of intralipid and ink. The calibration constants were used to calculate the absorption coefficients from the diffuse reflectance measurements of three volunteers (skin phototypes, II, IV and V) for sun-exposed and non-exposed areas on the arm.

  3. Absorption Coefficients of Particulate Matter off the Southwest Coast of Europe: A Contribution to Validation of the MERIS Sensor

    NASA Astrophysics Data System (ADS)

    Goela, P.; Icely, J.; Cristina, S.; Newton, A.

    2010-12-01

    Variability of particulate absorption coefficients was studied off the south-west coast of Portugal, as part of a validation exercise for the Medium Resolution Image Spectrometer Sensor. Regular sampling campaigns occurred at three stations on a transect from inshore to offshore to compare fluctuations in these coefficients at the local scale. Transmittance-reflectance method with sodium hypochlorite bleaching was used to determine absorption coefficients for phytoplankton and non-algal particles. Photosynthetic pigment concentrations were determined by High Performance Liquid Chromatography. Results show that the absorption of light by particulate matter is almost totally dependent on the phytoplankton, with no significant contribution from non-algal particles, both in coastal and oceanic waters. Specific phytoplankton coefficients show significant fluctuations between seasons and stations, ranging from 0.012 to 0.038 at 678 nm. Particulate absorption is dominant over dissolved absorption. The variations in the coefficients of absorption are analysed as a function of species assemblages.

  4. Parameterization of the Mie Extinction and Absorption Coefficients for Water Clouds.

    NASA Astrophysics Data System (ADS)

    Mitchell, David L.

    2000-05-01

    It was found that the anomalous diffraction approximation (ADA) could be made to approximate Mie theory for absorption and extinction in water clouds by parameterizing the missing physics: 1) internal reflection/refraction, 2) photon tunneling, and 3) edge diffraction. Tunneling here refers to processes by which tangential or grazing photons beyond the physical cross section of a spherical particle may be absorbed. Contributions of the above processes to extinction and/or absorption were approximated in terms of particle size, index of refraction, and wavelength. It was found that tunneling can explain most of the difference between ADA and Mie theory for water clouds in the thermal IR.The modified ADA yielded analytical expressions for the absorption and extinction efficiencies, Qabs and Qext, which were integrated over a gamma size distribution to yield expressions for the absorption and extinction coefficients, abs and ext. These coefficients were expressed in terms of the three gamma distribution parameters, which were related to measured properties of the size distribution: liquid water content, mean, and mass-median diameter. Errors relative to Mie theory for abs and ext were generally 10% for the effective radius range in water clouds of 5-30 m, for any wavelength in the solar or terrestrial spectrum. For broadband emissivities and absorptivities regarding terrestrial and solar radiation, the errors were less than 1.2% and 4%, respectively. The modified ADA dramatically reduces computation times relative to Mie theory while yielding reasonably accurate results.

  5. Thin-film absorption coefficients by attenuated-total-reflection spectroscopy.

    PubMed

    Holm, R T; Palik, E D

    1978-02-01

    The application of attenuated-total-reflection spectroscopy to the measurement of the absorption coefficient of thin films is presented. For low absorption the sensitivity of ATR is discussed in terms of the concept of an effective thickness. Both the case in which the refractive index of the film is higher and the case in which it is lower than that of the ATR trapezoid are considered. Experimental ATR data for antireflection-coating materials for laser windows is analyzed and compared with calorimetric data.

  6. Measurement and calculation of the sound absorption coefficient of pine wood charcoal

    NASA Astrophysics Data System (ADS)

    Suh, Jae Gap; Baik, Kyung min; Kim, Yong Tae; Jung, Sung Soo

    2013-10-01

    Although charcoal has been widely utilized for physical therapy and as a deodorant, water purifier, etc. due to its porous features, research on its role as a sound-absorbing material is rarely found. Thus, the sound absorption coefficients of pine wood charcoal were measured using an impedance tube and were compared with the theoretical predictions in the frequency range of 500˜ 5000 Hz. The theory developed in the current study only considers the lowest possible mode propagating along the air channels of the charcoal and shows good agreements with the measurements. As the frequency is increased, the sound absorption coefficients of pine wood charcoals also increase, but are lower than those of other commonly-used sound-absorbing materials.

  7. Simultaneous retrieval of temperature-dependent absorption coefficient and conductivity of participating media

    PubMed Central

    Ren, Yatao; Qi, Hong; Zhao, Fangzhou; Ruan, Liming; Tan, Heping

    2016-01-01

    A secondary optimization technique was proposed to estimate the temperature-dependent thermal conductivity and absorption coefficient. In the proposed method, the stochastic particle swarm optimization was applied to solve the inverse problem. The coupled radiation and conduction problem was solved in a 1D absorbing, emitting, but non-scattering slab exposed to a pulse laser. It is found that in the coupled radiation and conduction problem, the temperature response is highly sensitive to conductivity but slightly sensitive to the optical properties. On the contrary, the radiative intensity is highly sensitive to optical properties but slightly sensitive to thermal conductivity. Therefore, the optical and thermal signals should both be considered in the inverse problem to estimate the temperature-dependent properties of the transparent media. On this basis, the temperature-dependent thermal conductivity and absorption coefficient were both estimated accurately by measuring the time-dependent temperature, and radiative response at the boundary of the slab. PMID:26912418

  8. Infrared absorption-coefficient data on SF6 applicable to atmospheric remote sensing

    NASA Technical Reports Server (NTRS)

    Varanasi, P.; Gopalan, A.; Brannon, J. F., Jr.

    1992-01-01

    Spectral absorption coefficients, k(nu)/cm per atm, of SF6 have been measured in the central Q-branches of the nu(3)-fundamental at 947/cm at various temperature-pressure combinations representing tangent heights in solar-occultation experiments or layers in the atmosphere. The data obtained with the Doppler-limited spectral resolution (about 0.0001/cm) of a tunable-diode laser spectrometer are useful in the atmospheric remote sensing of this trace gas.

  9. Methane absorption coefficients for the jovian planets from laboratory, Huygens, and HST data

    NASA Astrophysics Data System (ADS)

    Karkoschka, Erich; Tomasko, Martin G.

    2010-02-01

    We use 11 data sets of methane transmission measurements within 0.4-5.5 μm wavelength to model the methane transmission for temperature and pressure conditions in the jovian planets. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methane absorption inside Titan's atmosphere ( Tomasko et al., 2008b, PSS 56, 624), and we provide a refined analysis. The last data set is a set of new Jupiter images by the Hubble Space Telescope to measure atmospheric transmission with Ganymede as the light source. Below 1000 nm wavelength, our resulting methane absorption coefficients are generally close to those by Karkoschka (1998, Icarus 133, 134), but we add descriptions of temperature and pressure dependence. One remaining inconsistency occurs between 882 and 902 nm wavelength where laboratory data predict larger absorptions in the jovian atmospheres than observed. We present possible explanations. Above 1000 nm, our analysis of the Huygens data confirms methane absorption coefficients by Irwin et al. (2006, Icarus 181, 309) at their laboratory temperatures. Huygens data also confirm Irwin's model of extrapolation to Titan's lower pressures. However, their model of extrapolation to Titan's lower temperatures predicts absorption coefficients up to 100 times lower than measured by Huygens. For each of ˜3700 wavelengths, we present a temperature dependence that is consistent with all laboratory data and the Huygens data. Since the Huygens data probe similar temperatures as many observations of Saturn, Uranus, Neptune, and Titan, our methane model will allow more reliable radiative transfer models for their atmospheres.

  10. The influence of surface preparation on the absorption coefficient of laser radiation

    NASA Astrophysics Data System (ADS)

    Kurp, Piotr; Mucha, Zygmunt; Mulczyk, Krystian; Gradoń, Ryszard; Trela, Paweł

    2016-12-01

    The absorption coefficient of the surface of a workpiece is of importance in laser treatment, particularly in the treatment where the temperature of an element must be strictly controlled. Laser surface treatment (such as hardening, metallic glazing) and laser forming can be primarily included in this type of technology. In another case, surface temperature must be precisely controlled, especially if structural changes are to be avoided. There are a number of ways to increase the absorption coefficient of the surface of an element. Since the laser forming is the research subject of the authors of the presented paper, it was necessary to determine the absorption coefficient for the different surfaces preparation of workpieces. Raw surface, oxidized surface, sandblasted surface, black enamel covered surface and waterglass covered surface were examined, respectively. The experiment was performed using a CO2 laser with a head for a surface treatment which generates a rectangular beam of dimensions 2x20 mm, and the samples were made of X5CrNi18-10 stainless steel.

  11. Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1990-01-01

    Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.

  12. Dependence of dose coefficients for inhaled 239Pu on absorption parameters.

    PubMed

    Suzuki, K; Sekimoto, H; Ishigure, N

    2001-01-01

    With regard to dissolution of particles in the respiratory tract after inhalation, the International Commission on Radiological Protection (ICRP) has classified all radionuclides into only three types according to the chemical form of compounds, and default values of absorption parameters are proposed for each type. However, it is just a simplification to estimate doses for practical use, and there is a possibility of unfitness in such an assortment. A code has been developed to reproduce the ICRP's dose coefficients for 239Pu, which is one of the most important elements for occupational exposure. By using this code, the respective absorption parameters were modified, and the effect owing to these changes evaluated. It was shown consequently that changes of absorption parameters do not greatly influence the effective doses of 239Pu for workers.

  13. Use of radial symmetry for the calculation of cylindrical absorption coefficients and optimal capillary loadings

    DOE PAGES

    Khalifah, Peter

    2015-02-01

    The problem of numerically evaluating absorption correction factors for cylindrical samples has been revisited using a treatment that fully takes advantage of the sample symmetry. It is shown that the path lengths for all points within the sample at all possible diffraction angles can be trivially determined once the angle-dependent distance distribution for a single line of points is calculated. This provides advantages in both computational efficiency and in gaining an intuitive understanding of the effects of absorption on diffraction data. A matrix of absorption coefficients calculated for µR products between 0 and 20 for diffraction angles θD of 0°more » to 90° were used to examine the influence of (1) capillary diameter and of (2) sample density on the overall scattered intensity as a function of diffraction angle, where µ is the linear absorption coefficient for the sample and R is the capillary radius. Based on this analysis, the optimal sample loading for a capillary experiment to maximize diffraction at angles of 0 – 50° is in general expected to be achieved when the maximum radius capillary compatible with the beam is used, and when the sample density is adjusted to be 3/(4µR) of its original density.« less

  14. Two-photon interband absorption coefficients in tungstate and molybdate crystals

    NASA Astrophysics Data System (ADS)

    Lukanin, V. I.; Karasik, A. Ya.

    2015-02-01

    Two-photon absorption (TPA) coefficients were measured in tungstate and molybdate crystals - BaWO4, KGW, CaMoO4, BaMoO4, CaWO4, PbWO4 and ZnWO4 upon different orientations of excitation polarization with respect to the crystallographic axes. Trains of 25 ps pulses with variable radiation intensities of third (349 nm) harmonics of passively mode-locked 1047 nm Nd:YLF laser were used for interband two-photon excitation of the crystals. It was suggested that in the case, when 349 nm radiation pumping energy exceeds the bandgap width (hν>Eg), the nonlinear excitation process can be considered as two-step absorption. The interband two-photon absorption in all the studied crystals induces the following one-photon absorption from the exited states, which affects the nonlinear process dynamics and leads to a hysteresis in the dependence of the transmission on the excitation intensity. This fact was taken into account under analysis of the experimental dependences of the reciprocal transmission on the excitation intensity. Laser excitation in the transparency region of the crystals caused stimulated Raman scattering (SRS) not for all the crystals studied. The measured nonlinear coefficients allowed us to explain the suppression of SRS in crystals as a result of competition between the SRS and TPA.

  15. Use of radial symmetry for the calculation of cylindrical absorption coefficients and optimal capillary loadings

    SciTech Connect

    Khalifah, Peter

    2015-02-01

    The problem of numerically evaluating absorption correction factors for cylindrical samples has been revisited using a treatment that fully takes advantage of the sample symmetry. It is shown that the path lengths for all points within the sample at all possible diffraction angles can be trivially determined once the angle-dependent distance distribution for a single line of points is calculated. This provides advantages in both computational efficiency and in gaining an intuitive understanding of the effects of absorption on diffraction data. A matrix of absorption coefficients calculated for µR products between 0 and 20 for diffraction angles θD of 0° to 90° were used to examine the influence of (1) capillary diameter and of (2) sample density on the overall scattered intensity as a function of diffraction angle, where µ is the linear absorption coefficient for the sample and R is the capillary radius. Based on this analysis, the optimal sample loading for a capillary experiment to maximize diffraction at angles of 0 – 50° is in general expected to be achieved when the maximum radius capillary compatible with the beam is used, and when the sample density is adjusted to be 3/(4µR) of its original density.

  16. Parameterization of the Mie extinction and absorption coefficients for water clouds

    SciTech Connect

    Mitchell, D.L.

    2000-05-01

    It was found that the anomalous diffraction approximation (ADA) could be made to approximate Mie theory for absorption and extinction in water clouds by parameterizing the missing physics: (1) internal reflection/refraction, (2) photon tunneling, and (3) edge diffraction. Tunneling here refers to processes by which tangential or grazing photons beyond the physical cross section of a spherical particle may be absorbed. Contributions of the above processes to extinction and/or absorption were approximated in terms of particle size, index of refraction, and wavelength. It was found that tunneling can explain most of the difference between ADA and Mie theory for water clouds in the thermal IR. The modified ADA yielded analytical expressions for the absorption and extinction efficiencies, Q{sub abs} and Q{sub ext}, which were integrated over a gamma size distribution to yield expressions for the absorption and extinction coefficients, {beta}{sub abs} and {beta}{sub ext}. These coefficients were expressed in terms of the three gamma distribution parameters, which were related to measured properties of the size distribution: liquid water content, mean, and mass-median diameter. Errors relative to Mie theory for {beta}{sub abs} and {beta}{sub ext} were generally {le}10% for the effective radius range in water clouds of 5--30 {micro}m, for any wavelength in the solar or terrestrial spectrum. For broadband emissivities and absorptivities regarding terrestrial and solar radiation, the errors were less than 1.2% and 4%, respectively. The modified ADA dramatically reduces computation times relative to Mie theory while yielding reasonably accurate results.

  17. Microwave Resonator Measurements of Atmospheric Absorption Coefficients: A Preliminary Design Study

    NASA Technical Reports Server (NTRS)

    Walter, Steven J.; Spilker, Thomas R.

    1995-01-01

    A preliminary design study examined the feasibility of using microwave resonator measurements to improve the accuracy of atmospheric absorption coefficients and refractivity between 18 and 35 GHz. Increased accuracies would improve the capability of water vapor radiometers to correct for radio signal delays caused by Earth's atmosphere. Calibration of delays incurred by radio signals traversing the atmosphere has applications to both deep space tracking and planetary radio science experiments. Currently, the Cassini gravity wave search requires 0.8-1.0% absorption coefficient accuracy. This study examined current atmospheric absorption models and estimated that current model accuracy ranges from 5% to 7%. The refractivity of water vapor is known to 1% accuracy, while the refractivity of many dry gases (oxygen, nitrogen, etc.) are known to better than 0.1%. Improvements to the current generation of models will require that both the functional form and absolute absorption of the water vapor spectrum be calibrated and validated. Several laboratory techniques for measuring atmospheric absorption and refractivity were investigated, including absorption cells, single and multimode rectangular cavity resonators, and Fabry-Perot resonators. Semi-confocal Fabry-Perot resonators were shown to provide the most cost-effective and accurate method of measuring atmospheric gas refractivity. The need for accurate environmental measurement and control was also addressed. A preliminary design for the environmental control and measurement system was developed to aid in identifying significant design issues. The analysis indicated that overall measurement accuracy will be limited by measurement errors and imprecise control of the gas sample's thermodynamic state, thermal expansion and vibration- induced deformation of the resonator structure, and electronic measurement error. The central problem is to identify systematic errors because random errors can be reduced by averaging

  18. Methamphetamine absorption by skin lipids: accumulated mass, partition coefficients, and the influence of fatty acids.

    PubMed

    Parker, K; Morrison, G

    2016-08-01

    Occupants of former methamphetamine laboratories, often residences, may experience increased exposure through the accumulation of the methamphetamine in the organic films that coat skin and indoor surfaces. The objectives of this study were to determine equilibrium partition coefficients of vapor-phase methamphetamine with artificial sebum (AS-1), artificial sebum without fatty acids (AS-2), and real skin surface films, herein called skin oils. Sebum and skin oil-coated filters were exposed to vapor-phase methamphetamine at concentrations ranging from 8 to 159 ppb, and samples were analyzed for exposure time periods from 2 h to 60 days. For a low vapor-phase methamphetamine concentration range of ~8-22 ppb, the equilibrium partition coefficient for AS-1 was 1500 ± 195 μg/g/ppb. For a high concentration range of 98-112 ppb, the partition coefficient was lower, 459 ± 80 μg/g/ppb, suggesting saturation of the available absorption capacity. The low partition coefficient for AS-2 (33 ± 6 μg/g/ppb) suggests that the fatty acids in AS-1 and skin oil are responsible for much high partition coefficients. We predict that the methamphetamine concentration in skin lipids coating indoor surfaces can exceed recommended surface remediation standards even for air concentrations well below 1 ppb.

  19. Diffusion Coefficients of Water and Leachables in Methacrylate-based Crosslinked Polymers using Absorption Experiments

    PubMed Central

    Parthasarathy, Ranganathan; Misra, Anil; Park, Jonggu; Ye, Qiang; Spencer, Paulette

    2012-01-01

    The diffusion of water into dentin adhesive polymers and leaching of unpolymerized monomer from the adhesive are linked to their mechanical softening and hydrolytic degradation. Therefore, diffusion coefficient data are critical for the mechanical design of these polymeric adhesives. In this study, diffusion coefficients of water and leachables were obtained for sixteen methacrylate-based crosslinked polymers using absorption experiments. The experimental mass change data was interpreted using numerical solution of the two-dimensional diffusion equations. The calculated diffusion coefficients varied from 1.05 × 10−8 cm2/sec (co-monomer TMTMA) to 3.15 × 10−8 cm2/sec (co-monomer T4EGDMA). Correlation of the diffusion coefficients with crosslink density and hydrophilicity showed an inverse trend (R2 = 0.41). The correlation of diffusion coefficient with crosslink density and hydrophilicity are closer for molecules differing by simple repeat units (R2 = 0.95). These differences in the trends reveal mechanisms of interaction of the diffusing water with the polymer structure. PMID:22430592

  20. Sound absorption coefficient in situ: an alternative for estimating soil loss factors.

    PubMed

    Freire, Rosane; Meletti de Abreu, Marco Henrique; Okada, Rafael Yuri; Soares, Paulo Fernando; GranhenTavares, Célia Regina

    2015-01-01

    The relationship between the sound absorption coefficient and factors of the Universal Soil Loss Equation (USLE) was determined in a section of the Maringá Stream basin, Paraná State, by using erosion plots. In the field, four erosion plots were built on a reduced scale, with dimensions of 2.0×12.5m. With respect to plot coverage, one was kept with bare soil and the others contained forage grass (Brachiaria), corn and wheat crops, respectively. Planting was performed without any type of conservation practice in an area with a 9% slope. A sedimentation tank was placed at the end of each plot to collect the material transported. For the acoustic system, pink noise was used in the measurement of the proposed monitoring, for collecting information on incident and reflected sound pressure levels. In general, obtained values of soil loss confirmed that 94.3% of material exported to the basin water came from the bare soil plot, 2.8% from the corn plot, 1.8% from the wheat plot, and 1.1% from the forage grass plot. With respect to the acoustic monitoring, results indicated that at 16kHz erosion plot coverage type had a significant influence on the sound absorption coefficient. High correlation coefficients were found in estimations of the A and C factors of the USLE, confirming that the acoustic technique is feasible for the determination of soil loss directly in the field.

  1. Measurements of the absorption and scattering coefficients of aerosol particles in suburb of Nanjing (China)

    NASA Astrophysics Data System (ADS)

    Yin, Yan; Chen, Yu; Wang, Weiwei; Yan, Jiade; Qian, Ling; Tong, Yaoqing; Lin, Zhenyi

    2008-08-01

    The absorption and scattering coefficients of atmospheric aerosols were continuously measured with a Photoacoustic Soot Spectrometer (PASS, DMT Inc. USA) at a suburb site of Nanjing, one of the regions experiencing rapid industrialization in China. The measurements were carried out during autumn and winter 2007. A preliminary analysis of the data shows that, the scattering coefficient, Bscat, is two to ten times larger than the absorption coefficient, Babs, implying that the aerosols formed/emitted in this area are more scattering than previous assumed, and can be more important in cooling the Earth-atmosphere system. The results also indicate that the absolute values of both parameters are very much dependent on the meteorological conditions, such as wind speed and direction, fog, rain, etc. as well as the time of the day. Higher values often appear at nighttimes when wind is weak, especially when a temperature inverse layer is present near the surface. Higher values of Bscat and Babs were also observed under hazy and foggy weather conditions or when wind is blown from east, where a large industrial zone is located. Simultaneous measurements of the number concentrations, chemical compositions, and size distributions of aerosol particles are used to explain the characteristics of the changes in Bscat and Babs.

  2. Quantifying the effect of finite spectral bandwidth on extinction coefficient of species in laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Manjeet; Singh, Jaswant; Singh, Baljit; Ghanshyam, C.

    2016-11-01

    The aim of this study is to quantify the finite spectral bandwidth effect on laser absorption spectroscopy for a wide-band laser source. Experimental analysis reveals that the extinction coefficient of an analyte is affected by the bandwidth of the spectral source, which may result in the erroneous conclusions. An approximate mathematical model has been developed for optical intensities having Gaussian line shape, which includes the impact of source's spectral bandwidth in the equation for spectroscopic absorption. This is done by introducing a suitable first order and second order bandwidth approximation in the Beer-Lambert law equation for finite bandwidth case. The derived expressions were validated using spectroscopic analysis with higher SBW on a test sample, Rhodamine B. The concentrations calculated using proposed approximation, were in significant agreement with the true values when compared with those calculated with conventional approach.

  3. Effect of sealants of the sound absorption coefficients of acoustical friable insulating materials

    NASA Astrophysics Data System (ADS)

    Wayman, J. L.; Lory, M. K.

    1984-10-01

    Acoustical friable insulating materials (AFIM), which often in the past contained asbestos, have been used for sound control since the mid 1930's. Because of their widespread use and the ease of fiber dissemination, friable asbestos materials are considered to be the major source of asbestos fiber contamination in the indoor environment. Encapsulation of asbestos materials with a commercial sealant product is one of several methods used to control potential asbestos exposure in rooms. A sealant product that preserves most of the acoustical properties of the material is preferred in this usage. AFIM sample materials were treated with 6 types of sealants and the effects on normally incident absorption coefficients from 100 to 2500 Hz were measured using a fixed, dual-microphone technique. Penetrating type sealants were found to have a less detrimental effect on sound absorption than those of a bridging type.

  4. The effective air absorption coefficient for predicting reverberation time in full octave bands.

    PubMed

    Wenmaekers, R H C; Hak, C C J M; Hornikx, M C J

    2014-12-01

    A substantial amount of research has been devoted to producing a calculation model for air absorption for pure tones. However, most statistical and geometrical room acoustic prediction models calculate the reverberation time in full octave bands in accordance with ISO 3382-1 (International Organization for Standardization, 2009). So far, the available methods that allow calculation of air absorption in octave bands have not been investigated for room acoustic applications. In this paper, the effect of air absorption on octave band reverberation time calculations is investigated based on calculations. It is found that the approximation method, as described in the standard ANSI S1.26 (American National Standards Institute, 1995), fails to estimate accurate decay curves for full octave bands. In this paper, a method is used to calculate the energy decay curve in rooms based on a summation of pure tones within the band. From this decay curve, which is found to be slightly concave upwards, T20 and T30 can be determined. For different conditions, an effective intensity attenuation coefficient mB ;eff for the full octave bands has been calculated. This mB ;eff can be used for reverberation time calculations, if results are to be compared with T20 or T30 measurements. Also, guidelines are given for the air absorption correction of decay curves, measured in a scale model.

  5. The coefficient of bond thermal expansion measured by extended x-ray absorption fine structure.

    PubMed

    Fornasini, P; Grisenti, R

    2014-10-28

    The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient α(bond)(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient α(tens)(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where α(bond) prevails over α(tens); this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed.

  6. Water in the Earth's Mantle: Mineral-specific IR Absorption Coefficients and Radiative Thermal Conductivities

    NASA Astrophysics Data System (ADS)

    Thomas, S. M.

    2015-12-01

    Minor and trace element chemistry, phase relations, rheology, thermal structure and the role of volatiles and their abundance in the deep Earth mantle are still far from fully explored, but fundamental to understanding the processes involved in Earth formation and evolution. Theory and high pressure experiments imply a significant water storage capacity of nominally anhydrous minerals, such as majoritic garnet, olivine, wadsleyite and ringwoodite, composing the Earth's upper mantle and transition zone to a depth of 660 km. Studying the effect of water incorporation on chemical and physical mineral properties is of importance, because the presence of trace amounts of water, incorporated as OH through charge-coupled chemical substitutions into such nominally anhydrous high-pressure silicates, notably influences phase relations, melting behavior, conductivity, elasticity, viscosity and rheology. Knowledge of absolute water contents in nominally anhydrous minerals is essential for modeling the Earth's interior water cycle. One of the most common and sensitive tools for water quantification is IR spectroscopy for which mineral-specific absorption coefficients are required. Such calibration constants can be derived from hydrogen concentrations determined by independent techniques, such as secondary ion mass spectrometry, Raman spectroscopy or proton-proton(pp)-scattering. Here, analytical advances and mineral-specific IR absorption coefficients for the quantification of H2O in major phases of the Earth's mantle will be discussed. Furthermore, new data from optical absorption measurements in resistively heated diamond-anvil cells at high pressures and temperatures up to 1000 K will be presented. Experiments were performed on synthetic single-crystals of olivine, ringwoodite, majoritic garnet, and Al-bearing phase D with varying iron, aluminum and OH contents to calculate radiative thermal conductivities and study their contribution to heat transfer in the Earth's interior

  7. Variation of Phytoplankton Absorption Coefficients in the Northern South China Sea during Spring and Autumn

    DTIC Science & Technology

    2007-05-21

    samples were collected with 1.7 L Niskin bottles mounted on a rosette equipped with a SBE19 CTD which provides temperature and salinity data. Samples were...21 November is 2002) on board R/V Yanping I1. Figure 1 shows the stations for CTD surveys and ab- sorption sampling . The 2001 cruise involved one...were sampled in both cruise legs for absorption coefficients (the second sampling is annotated as Sta. 6’ and Sta. 2’, respectively). 1559 Our sample

  8. Two-photon absorption and Kerr coefficients of silicon for 850-2200 nm

    NASA Astrophysics Data System (ADS)

    Bristow, Alan D.; Rotenberg, Nir; van Driel, Henry M.

    2007-05-01

    The degenerate two-photon absorption coefficient β and Kerr nonlinearity n2 are measured for bulk Si at 300K using 200fs pulses with carrier wavelength of 850<λ<2200nm for which indirect gap transitions occur. With a broad peak near the indirect gap and maximum value of 2±0.5cm/GW, the dispersion of β compares favorably with theoretical calculations of Garcia and Kalyanaraman [J. Phys. B 39, 2737 (2006)]. Within our wavelength range, n2 varies by a factor of 4 with a peak value of 1.2×10-13cm2/W at λ =1800nm.

  9. Vapor-Phase Absorptivity Coefficient of Ethyl N,N-Dimethylphosphoramidocyanidate

    DTIC Science & Technology

    2010-01-01

    diluted in solvent by gas chromotography -mass spectrometry (GC-MS) indicated 3.4% triethyl phosphate (TEPO), as well ə% each of 0-ethyl-N,N-dimethyl...absorptivity coefficient of the chemical warfare agent ethyl N,N-dimethyl- phosphoramidocyanidate ( GA ) in the mid-infrared (4000-550 cm"’) at a...spectral resolution of 0.125 cm"’. The GA used in the feedstock was purified by fractional distillation and analyzed by nuclear magnetic resonance and

  10. Temperature and pressure dependence of dichloro-difluoromethane (CF2C12) absorption coefficients for CO2 waveguide laser radiation

    NASA Technical Reports Server (NTRS)

    Harward, C. N.

    1977-01-01

    Measurements were performed to determine the pressure and temperature dependence of CFM-12 absorption coefficients for CO2 waveguide laser radiation. The absorption coefficients of CFM-12 for CO2 waveguide laser radiation were found to have no spectral structure within small spectral bandwidths around the CO2 waveguide laser lines in the CO2 spectral band for pressures above 20 torr. All of the absorption coefficients for the CO2 laser lines studied are independent of pressure above 100 torr, except for the P(36) laser CO2 spectral band. The absorption coefficients associated with the P(42) line in the same band showed the greatest change with temperature, and it also has the largest value of all the lines studied.

  11. A comparison study of linear reconstruction techniques for diffuse optical tomographic imaging of absorption coefficient

    NASA Astrophysics Data System (ADS)

    Gaudette, Richard J.; Brooks, Dana H.; Di Marzio, Charles A.; Kilmer, Misha E.; Miller, Eric L.; Gaudette, Thomas; Boas, David A.

    2000-04-01

    We compare, through simulations, the performance of four linear algorithms for diffuse optical tomographic reconstruction of the three-dimensional distribution of absorption coefficient within a highly scattering medium using the diffuse photon density wave approximation. The simulation geometry consisted of a coplanar array of sources and detectors at the boundary of a half-space medium. The forward solution matrix is both underdetermined, because we estimate many more absorption coefficient voxels than we have measurements, and ill-conditioned, due to the ill-posedness of the inverse problem. We compare two algebraic techniques, ART and SIRT, and two subspace techniques, the truncated SVD and CG algorithms. We compare three-dimensional reconstructions with two-dimensional reconstructions which assume all inhomogeneities are confined to a known horizontal slab, and we consider two `object-based' error metrics in addition to mean square reconstruction error. We include a comparison using simulated data generated using a different FDFD method with the same inversion algorithms to indicate how our conclusions are affected in a somewhat more realistic scenario. Our results show that the subspace techniques are superior to the algebraic techniques in localization of inhomogeneities and estimation of their amplitude, that two-dimensional reconstructions are sensitive to underestimation of the object depth, and that an error measure based on a location parameter can be a useful complement to mean squared error.

  12. Spectral absorption coefficients of argon and silicon and spectral reflectivity of aluminum

    NASA Technical Reports Server (NTRS)

    Krascella, N. L.

    1972-01-01

    A theoretical investigation was conducted to estimate the spectral properties of argon as a function of pressure, temperature, and wave number. The spectral characteristics of the argon buffer gas exert a strong influence on radiative energy transfer in the in-reactor test configuration of the nuclear light bulb engine. An existing computer program was modified and used to calculate the spectral absorption coefficients of argon at total pressures of 50, 100, 250, 500, 750 and 1000 atm in the temperature interval between 1000 and 30,000 K. At each pressure and temperature, spectral properties were calculated for forty-seven wave numbers in the interval between 1000 and 1,000,000 cm/1. Estimates of the spectral absorption coefficients of silicon were made as part of an evaluation of silicon vapor as a possible buffer-gas seeding agent for the reference nuclear light bulb engine. Existing cross-section data were used to calculate the spectral characteristics of silicon at twenty-four temperatures in the interval between 2000 and 10,000 K.

  13. Modeling the cumulative distribution of absorption coefficients of gases using the generalized k-moment method

    NASA Astrophysics Data System (ADS)

    André, Frédéric; Solovjov, Vladimir; Vaillon, Rodolphe; Lemonnier, Denis

    2013-07-01

    The generalized k-moment method is formulated in terms of Cutteridge-Devyatov polynomials (CDP). In this novel approach, the moments involved are spectral averages of integer powers of the logarithm of the absorption coefficient. The technique to obtain k-distributions from those generalized moments is detailed both theoretically and from a practical point of view. Its outputs are afterward assessed against reference data in several test cases of increasing complexity. Indeed, the first ones involve single lines in the Lorentz, Doppler and Voigt regimes. The most sophisticated situations investigated in this work concern applications of the method to high resolution LBL data for pure CO2 at temperatures between 300K and 2300K and at atmospheric pressure. In any case, the CDP solution to the generalized k-moment problem is found to provide very accurate results. The present technique outperforms our previous approach to k-moment modeling of the cumulative distribution of absorption coefficients of gases that were based on first, second, first inverse and logarithmic moments, in all the situations investigated. Equations required to apply the model are provided in the paper, both over narrow bands and the full spectrum.

  14. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    PubMed

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations.

  15. Measuring absorption coefficient of scattering liquids using a tube inside an integrating sphere.

    PubMed

    Villanueva, Yolanda; Veenstra, Colin; Steenbergen, Wiendelt

    2016-04-10

    A method for measuring the absorption coefficient μa of absorbing and scattering liquid samples is presented. The sample is injected into a small transparent tube mounted through an integrating sphere. Two models for determining the absorption coefficient using the relative optical output signal are described and validated using aqueous ink absorbers of 0.5 vol.% (0.3  mm-1a<1.55  mm-1) and 1.0 vol.% (1.0  mm-1a<4.0  mm-1) concentrations with 1 vol.% (μs'≈1.4  mm-1) and 10 vol.% (μs'≈14  mm-1) Intralipid dilutions. The low concentrations give μa and μs values, which are comparable with those of biological tissues. One model assumes a uniform light distribution within the sample, which is valid for low absorption. Another model considers light attenuation that obeys Lambert-Beer's law, which may be used for relatively high absorption. Measurements with low and high scattering samples are done for the wavelength range of 400-900 nm. Measured spectra of purely absorbing samples are within 15% agreement with measurements using standard transmission spectrophotometry. For 0.5 vol.% ink absorbers and at wavelengths below 700 nm, measured μa values are higher for samples with low scattering and lower for those with high scattering. At wavelengths above 700 nm, measured μa values do not vary significantly with amount of scattering. For 1.0 vol.% ink absorbers, measured spectra do not change with low scattering. These results indicate that the method can be used for measuring absorption spectra of scattering liquid samples with optical properties similar to biological absorbers, particularly at wavelengths above 700 nm, which is difficult to accomplish with standard transmission spectrophotometry.

  16. Highly Dynamic Ligand Binding and Light Absorption Coefficient of Cesium Lead Bromide Perovskite Nanocrystals.

    PubMed

    De Roo, Jonathan; Ibáñez, Maria; Geiregat, Pieter; Nedelcu, Georgian; Walravens, Willem; Maes, Jorick; Martins, Jose C; Van Driessche, Isabel; Kovalenko, Maksym V; Hens, Zeger

    2016-02-23

    Lead halide perovskite materials have attracted significant attention in the context of photovoltaics and other optoelectronic applications, and recently, research efforts have been directed to nanostructured lead halide perovskites. Collodial nanocrystals (NCs) of cesium lead halides (CsPbX3, X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over the entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects of their chemistry and photophysics such as surface chemistry and quantitative light absorption. Here, we elaborate on the synthesis of CsPbBr3 NCs and their surface chemistry. In addition, the intrinsic absorption coefficient was determined experimentally by combining elemental analysis with accurate optical absorption measurements. (1)H solution nuclear magnetic resonance spectroscopy was used to characterize sample purity, elucidate the surface chemistry, and evaluate the influence of purification methods on the surface composition. We find that ligand binding to the NC surface is highly dynamic, and therefore, ligands are easily lost during the isolation and purification procedures. However, when a small amount of both oleic acid and oleylamine is added, the NCs can be purified, maintaining optical, colloidal, and material integrity. In addition, we find that a high amine content in the ligand shell increases the quantum yield due to the improved binding of the carboxylic acid.

  17. The Optical Absorption Coefficient of Bean Seeds Investigated Using Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sanchez-Hernandez, G.; Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.; Perez-Reyes, M. C. J.; Martinez, E. Moreno

    2015-06-01

    A knowledge about seed optical parameters is of great relevance in seed technology practice. Such parameters provide information about its absorption and reflectance, which could be useful for biostimulation processes, by light sources, in early stages of seed germination. In the present research photoacoustic spectroscopy (PAS) and the Rosencwaig and Gersho model were used to determine the optical absorption coefficient () of five varieties of bean seeds ( Phaseolus vulgaris L.), of different productive cycles; the seeds were biostimulated by laser treatment to evaluate the effects of biostimulation pre-sowing. It was found that the bean varieties V1, V2, V4, and V5 were optically opaque in the visible spectrum; in the case of the V3 variety, this sample was optically transparent from 680 nm. The varieties of the studied bean seeds showed significant statistical differences in sizes and also in their optical absorption spectra. The biostimulation effects showed that the seed samples with a higher optical penetration length had a positive biostimulation, in the percentage of germination, obtaining an enhancement of 47 % compared to the control sample. The utility of PAS for the optical characterization of seeds has been demonstrated in this study of the laser biostimulation process of this kind of samples.

  18. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  19. Tomographic imaging of absolute optical absorption coefficient in turbid media using combined photoacoustic and diffusing light measurements.

    PubMed

    Yin, Lu; Wang, Qiang; Zhang, Qizhi; Jiang, Huabei

    2007-09-01

    We present a new method that can provide high resolution images of absolute optical absorption coefficient in heterogeneous turbid media. In this method, acoustic measurements in conventional photoacoustic tomography are combined with diffusing light measurements to separate the product of absorption coefficient and optical fluence or photon density. We validate this method using a series of tissuelike phantom experiments. The experimental results show that targets as small as 0.5 mm in diameter with optical absorption contrasts as low as 1.5 relative to a 50 mm diameter scattering background medium can be clearly detected.

  20. Experimental investigation of X-ray spectral absorption coefficients in heated Al and Ge on the Iskra-5 laser facility

    SciTech Connect

    Bondarenko, S V; Garanin, Sergey G; Zhidkov, N V; Pinegin, A V; Suslov, N A

    2012-01-31

    We set forth the data of experimental investigation of X-ray spectral absorption coefficients in the 1.1 - 1.6 keV photon energy range for Al and Ge specimens bulk heated by soft X-ray radiation. Two experimental techniques are described: with the use of one facility channel and the heating of specimens by the X-ray radiation from a plane burnthrough target, as well as with the use of four channels and the heating by the radiation from two cylindrical targets with internal input of laser radiation. The X-ray radiation absorption coefficients were studied by way of transmission absorption spectroscopy using backlighting X-ray radiation from a point source. The results of investigation of X-ray spectral absorption coefficients on the 1s - 2p transitions in Al atoms and the 2p - 3d transitions in Ge atoms are presented.

  1. Remote-Sensing Technique for Determination of the Volume Absorption Coefficient of Turbid Water

    NASA Astrophysics Data System (ADS)

    Sydor, Michael; Arnone, Robert A.; Gould, Richard W., Jr.; Terrie, Gregory E.; Ladner, Sherwin D.; Wood, Christoper G.

    1998-07-01

    We use remote-sensing reflectance from particulate R rs to determine the volume absorption coefficient a of turbid water in the 400 700-nm spectral region. The calculated and measured values of a ( ) show good agreement for 0 . 5 a 10 (m 1 ). To determine R rs from a particulate, we needed to make corrections for remote-sensing reflectance owing to surface roughness S rs . We determined the average spectral distribution of S rs from the difference in total remote-sensing reflectance measured with and without polarization. The spectral shape of S rs showed an excellent fit to theoretical formulas for glare based on Rayleigh and aerosol scattering from the atmosphere.

  2. The Optical Absorption Coefficient of Maize Grains Investigated by Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodríguez-Páez, C. L.; Carballo-Carballo, A.; Rico-Molina, R.; Hernández-Aguilar, C.; Domínguez-Pacheco, A.; Cruz-Orea, A.; Moreno-Martínez, E.

    2017-01-01

    In the maize and tortilla industry, it is important to characterize the color of maize ( Zea mays L.) grain, as it is one of the attributes that directly affect the quality of the tortillas consumed by the population. For this reason, the availability of alternative techniques for assessing and improving the quality of grain is valued. Photoacoustic spectroscopy has proven to be a useful tool for characterizing maize grain. So, the objective of the present study was to determine the optical absorption coefficient β of the maize grain used to make tortillas from two regions of Mexico: (a) Valles Altos, 2012-2013 production cycle and (b) Guasave, Sinaloa, 2013-2014 production cycle. Traditional reflectance measurements, physical characteristics of the grain and nutrient content were also calculated. The experimental results show different characteristics for maize grains.

  3. Magnetic resonance imaging of acoustic streaming: absorption coefficient and acoustic field shape estimation.

    PubMed

    Madelin, Guillaume; Grucker, Daniel; Franconi, Jean-Michel; Thiaudiere, Eric

    2006-07-01

    In this study, magnetic resonance imaging (MRI) is used to visualize acoustic streaming in liquids. A single-shot spin echo sequence (HASTE) with a saturation band perpendicular to the acoustic beam permits the acquisition of an instantaneous image of the flow due to the application of ultrasound. An average acoustic streaming velocity can be estimated from the MR images, from which the ultrasonic absorption coefficient and the bulk viscosity of different glycerol-water mixtures can be deduced. In the same way, this MRI method could be used to assess the acoustic field and time-average power of ultrasonic transducers in water (or other liquids with known physical properties), after calibration of a geometrical parameter that is dependent on the experimental setup.

  4. Measurement of acoustic absorption coefficient with phase-conjugate ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Smagin, N. V.; Krutyansky, L. M.; Brysev, A. P.; Bunkin, F. V.

    2011-07-01

    Experimental results on measurements of the acoustic absorption coefficient in test objects that were obtained with two methods, i.e., a standard insert-substitution method and a modification thereof using phase-conjugate waves, are given. Samples of gelatin and biological tissue in vitro (porcine muscle fibers) were used as test objects. Gelatin objects were manufactured that were both homogeneous and with inhomogeneities in the form of a rough surface or inclusions (air bubbles) distributed over the volume. A rough surface leads mainly to phase distortions of a probe beam, while bubble inclusions cause additional field scattering. For all homogeneous samples, both compared methods produce identical results. In the case of inhomogeneous samples including biological tissues, absorption measurement by a standard method may lead to significant errors. It is demonstrated that the use of properties of phase-conjugate waves provides an opportunity to eliminate almost completely the measurement error connected with phase distortions and reduce the error in the case of a medium with scatterers.

  5. Two-dimensional poroelastic acoustical foam shape design for absorption coefficient maximization by topology optimization method.

    PubMed

    Lee, Joong Seok; Kim, Yoon Young; Kim, Jung Soo; Kang, Yeon June

    2008-04-01

    Optimal shape design of a two-dimensional poroelastic acoustical foam is formulated as a topology optimization problem. For a poroelastic acoustical system consisting of an air region and a poroelastic foam region, two different physical regions are continuously changed in an iterative design process. To automatically account for the moving interfaces between two regions, we propose a new unified model to analyze the whole poroelastic acoustical foam system with one set of governing equations; Biot's equations are modified with a material property interpolation from a topology optimization method. With the unified analysis model, we carry out two-dimensional optimal shape design of a poroelastic acoustical foam by a gradient-based topology optimization setting. The specific objective is the maximization of the absorption coefficient in low and middle ranges of frequencies with different amounts of a poroelastic material. The performances of the obtained shapes are compared with those of well-known wedge shapes, and the improvement of absorption is physically interpreted.

  6. Study of the absorption coefficient of alpha particles to lower hybrid waves in tokamak

    SciTech Connect

    Wang, Jianbing Zhang, Xianmei Yu, Limin Zhao, Xiang

    2014-02-12

    Part of the energy of the Lower Hybrid (LH) waves may be absorbed by the α particles via the so-called perpendicular landau damping mechanism, which depends on various parameters of fusion reactors and the LH waves. In this article, we calculate the absorption coefficient γ{sub α} of LH waves due to α particles. Results show that, the γ{sub α} increases with the parallel refraction index n{sub ∥} while deceases with increasing the frequency of LH waves ω{sub LH} over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption, and there is a peak value of γ{sub α} when n{sub e}≈8×10{sup 19}m{sup −3} for ITER-like scenario. The thermal corrections to the cold plasma dispersion relation will change the damping rate to a certain extent under some specific conditions. We have also evaluated the fraction of LH power absorbed by the alpha particles, η ≈ 0.47% and 4.1% for an LH frequency of 5 GHz and 3.7 GHz respectively for ITER-like scenario. This work gives the effective reference for the choice of parameters of future fusion reactors.

  7. Approximating the near-edge mass absorption coefficients for Ni using an ultra-thin bimetal foil

    DOE PAGES

    Alkire, Randall W.

    2016-11-01

    In an effort to improve the characteristics of a fluorescing metal-foil-based beam position monitor, a new bimetal ultra-thin (0.98/0.67 µm) Ti–Ni foil was introduced to replace an existing single-element ultra-thin 0.5 µm thick Cr foil. During characterization it was determined that absorption measurements on the bimetal foil could be used to fit the Ni mass absorption coefficients accurately in the vicinity of the NiKedge. Comparison with experimental results from the literature demonstrated that the fitting procedure produced coefficients with uncertainties of the order of ±1%. Once determined, these fit coefficients allowed the thickness of an independently mounted 8 µm thickmore » Ni foil to be computed from absorption measurements instead of relying on a tool-based measurement of the foil thickness. Using the 8 µm thick foil, a continuous map of Ni mass absorption coefficients was produced at 1 eV resolution throughout the near-edge region. Lastly, this high-resolution map marks a significant improvement over the existing NIST XCOM or FFAST database mass absorption coefficients, which have estimated errors of 10–20% for the near-edge region.« less

  8. Approximating the near-edge mass absorption coefficients for Ni using an ultra-thin bimetal foil

    SciTech Connect

    Alkire, Randall W.

    2016-11-01

    In an effort to improve the characteristics of a fluorescing metal-foil-based beam position monitor, a new bimetal ultra-thin (0.98/0.67 µm) Ti–Ni foil was introduced to replace an existing single-element ultra-thin 0.5 µm thick Cr foil. During characterization it was determined that absorption measurements on the bimetal foil could be used to fit the Ni mass absorption coefficients accurately in the vicinity of the NiKedge. Comparison with experimental results from the literature demonstrated that the fitting procedure produced coefficients with uncertainties of the order of ±1%. Once determined, these fit coefficients allowed the thickness of an independently mounted 8 µm thick Ni foil to be computed from absorption measurements instead of relying on a tool-based measurement of the foil thickness. Using the 8 µm thick foil, a continuous map of Ni mass absorption coefficients was produced at 1 eV resolution throughout the near-edge region. Lastly, this high-resolution map marks a significant improvement over the existing NIST XCOM or FFAST database mass absorption coefficients, which have estimated errors of 10–20% for the near-edge region.

  9. IR Absorption Coefficients for the Quantification of Water in Hydrous Ringwoodite

    NASA Astrophysics Data System (ADS)

    Thomas, S.; Jacobsen, S. D.; Bina, C. R.; Smyth, J. R.; Frost, D. J.

    2009-12-01

    Raman spectroscopy, combined with the ‘Comparator technique’ has been developed to determine water contents ranging from a few wt ppm to wt% in glasses and nominally anhydrous minerals including garnets, olivine, and SiO2 polymorphs (Thomas et al. 2009). The routine is one promising example of quantification tools to determine mineral specific molar absorption coefficients (ɛ) for IR spectroscopy. Mineral specific absorption coefficients are required because general IR calibrations do not necessarily apply to minerals with water incorporated as hydroxyl point defects. Here we utilize the ‘Comparator technique’ to provide ɛ-values for a set of synthetic Fe-free and Fe-bearing (Fo90) ringwoodites, as well as for γ-Mg2GeO4. Ringwoodite is considered one of the major phases of the Earth’s lower transition zone (520-660 km depth) and the knowledge of its absolute water storage capacity is essential for modeling the Earth’s deep water cycle. Samples were synthesized at variable P-T conditions in a multi-anvil press and cover a range of OH contents. Single-crystals were characterized using X-ray diffraction and IR spectroscopy. Mineral specific IR absorption coefficients were calculated from independently determined water contents from Raman spectroscopy. Unpolarized IR spectra of Mg-ringwoodite show broad absorption features in the OH region with band maxima at ~2350, 2538, 3127, 3172, 3598 and 3688 cm-1. In the spectra of Fe-bearing ringwoodite and γ-Mg2GeO4 the maxima of the main OH band are shifted to 3172 cm-1 and 3207 cm-1, respectively. For Mg-ringwoodite with the mean wavenumber (area-weighted average of the peak position) of 3109 cm-1 an ɛ-value of 170000 ± 51000 L cm-2 / molH2O was determined. For a Fo90 sample with the mean wavenumber of 3132 cm-1 the value was calculated to be 123000 ± 37000 L cm-2 / molH2O. The latter two values are in good agreement with the data from the linear calibration of ~159000 L cm-2 / molH2O and ~153000 L cm-2

  10. Analytical modeling of photon absorption coefficient in mono and bilayer circular graphene quantum dots for light absorber applications

    NASA Astrophysics Data System (ADS)

    Tamandani, Shahryar; Darvish, Ghafar

    2017-02-01

    We present an analytical method to calculate photon absorption coefficient in mono and bilayer circular graphene quantum dots (CGQDs). We use kobo equation to extract new closed relation as the main goal. First, we calculate real and imaginary part of optical conductance separately. Then, joint density of states is obtained using a new relation that was extracted for the energy levels of mono and bilayer circular grapheme quantum dots. In this work we use closed equations to calculate energy levels in CGQDs. Next we obtain a new closed formula to calculate the photon absorption coefficient. The results show that the absorption coefficient is related to the size of CGQDs and number of layers. The photon absorption coefficient becomes lower with larger size of CGQDs. It is seen that the results of our method is compatible with the results of practical works. We also compare photon absorption in biased and unbiased bilayer CGQDs and investigate the effect of external magnetic field on photon absorption. rights reserved

  11. A new method to retrieve spectral absorption coefficient of highly-scattering and weakly-absorbing materials

    NASA Astrophysics Data System (ADS)

    Dombrovsky, Leonid A.

    2016-03-01

    A significant uncertainty in the absorption coefficient of highly scattering dispersed materials is typical in the spectral ranges of very weak absorption. The traditional way to identify the main absorption and scattering characteristics of semi-transparent materials is based on spectral measurements of normal-hemispherical reflectance and transmittance for the material sample. Unfortunately this way cannot be used in the case of in vivo measurements of optical properties of biological tissues. A method suggested in the present paper is based on thermal response to the periodic radiative heating of the open surface of a semi-transparent material. It is shown that the period of a variation of the surface temperature is sensitive to the value of an average absorption coefficient in the surface layer. As a result, the monochromatic external irradiation combined with the surface temperature measurements can be used to retrieve the spectral values of absorption coefficient. Possible application of this method to porous semi-transparent ceramics is considered. An example problem is also solved to illustrate the applicability of this method to human skin. The approach suggested enables one to estimate an average absorption coefficient of human skin of a patient just before the thermal processing.

  12. Spatially resolved absolute diffuse reflectance measurements for noninvasive determination of the optical scattering and absorption coefficients of biological tissue

    NASA Astrophysics Data System (ADS)

    Kienle, Alwin; Lilge, Lothar; Patterson, Michael S.; Hibst, Raimund; Steiner, Rudolf; Wilson, Brian C.

    1996-05-01

    The absorption and transport scattering coefficients of biological tissues determine the radial dependence of the diffuse reflectance that is due to a point source. A system is described for making remote measurements of spatially resolved absolute diffuse reflectance and hence noninvasive, noncontact estimates of the tissue optical properties. The system incorporated a laser source and a CCD camera. Deflection of the incident beam into the camera allowed characterization of the source for absolute reflectance measurements. It is shown that an often used solution of the diffusion equation cannot be applied for these measurements. Instead, a neural network, trained on the results of Monte Carlo simulations, was used to estimate the absorption and scattering coefficients from the reflectance data. Tests on tissue-simulating phantoms with transport scattering coefficients between 0.5 and 2.0 mm-1 and absorption coefficients between 0.002 and 0.1 mm -1 showed the rms errors of this technique to be 2.6% for the transport scattering coefficient and 14% for the absorption coefficients. The optical properties of bovine muscle, adipose, and liver tissue, as well as chicken muscle (breast), were also measured ex vivo at 633 and 751 nm. For muscle tissue it was found that the Monte Carlo simulation did not agree with experimental measurements of reflectance at distances less than 2 mm from the incident beam. Carlo, neural network.

  13. Absorption Coefficient, Molecular Composition, and Photodegradation of Different Types of Brown Carbon Aerosols

    NASA Astrophysics Data System (ADS)

    Lee, H. J.; Aiona, P. K.; Nizkorodov, S.; Laskin, J.; Laskin, A.

    2014-12-01

    Atmospheric aerosols that absorb solar radiation have a direct effect on climate. Brown carbon (BrC) represents the type of carbonaceous aerosols characterized by large absorption coefficients in the near-UV range of the spectrum. BrC can be either directly emitted into the atmosphere from combustion sources, or be formed in the atmosphere through multi-phase reactions, such as aging of secondary organic aerosols (SOA) mediated by ammonium sulfate (AS). Under the conditions of exposure to solar radiation, both primary and secondary BrC can potentially change their molecular composition and optical properties as a result of photodegradation of chromophoric compounds. This presentation will discuss the molecular level composition, the absorption and fluorescence spectra, and the mechanism of photodegradation among several representative types of BrC. The primary BrC samples include aerosol produced by smoldering wood combustion. The secondary BrC samples include AS aged products of chamber-generated SOA, products of reaction between methylglyoxal and AS, and SOA produced by the hogh-NOx photooxdiation of aromatic compounds, such as naphthalene. This presentation will also include preliminary data on the absorption and fluorescence spectra of photo-degraded bioaerosols. In all cases, absorption spectra of extracted bulk samples are measured during irradiation by a known flux of UV or visible light. The molecular level composition of the fresh and photobleached samples are characterized by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Photobleaching of BrC is found to occur over a range of atmospherically relevant time scales. In many cases, the molecular level composition of photobleached BrC exhibits only subtle changes suggesting that the optical and fluorescence properties of BrC are controlled by a few compounds present in low quantities. The observed fluorescence from non-biological BrC indicates potential issues in using fluorescence

  14. Reduction of the bulk absorption coefficient in silicon optics for high-energy lasers through defect engineering.

    PubMed

    Goodman, W A; Goorsky, M S

    1995-06-20

    We engineered a factor-of-4 reduction in the bulk absorption coefficient over the 2.6-to-3.0-µm bandwidth in single-crystal Czochralski silicon optics for high-energy infrared lasers with high-temperature annealing treatments. Defect engineering adapted from the integrated circuit industry has been used to reduce the absorption coefficient across the 1.5-to-5-µm bandwidth for substrates up to 5 cm thick. A high-temperature oxygen-dispersion anneal dissolves precipitates and thermal donors that are present in the as-grown material. The process has been verified experimentally with Fourier transform infrared spectroscopy, infrared laser calorimetry, and Hall measurements. Reduction of the absorption coefficient results in less substrate heating and thermal distortion of the optical surface. The process is appropriate for other silicon infrared optics applications such as thermal-imaging systems, infrared windows, and spectrophotometers.

  15. Absorption coefficients for the 6190-A CH4 band between 290 and 100 K with application to Uranus' atmosphere

    NASA Technical Reports Server (NTRS)

    Smith, Wm. Hayden; Conner, Charles P.; Baines, Kevin H.

    1990-01-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH4 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum.

  16. Absorption coefficients for the 6190-A CH sub 4 band between 290 and 100 K with application to Uranus' atmosphere

    SciTech Connect

    Smith, WM.H.; Conner, C.P.; Baines, K.H. JPL, Pasadena, CA )

    1990-05-01

    A novel laser intracavity photoacoustic spectroscopy method allowing high sample control accuracy due to the small sample volume required has been used to obtain absorption coefficients for the CH{sub 4} 6190 A band as a function of temperature, from 290 to 100 K. The peak absorption coefficient is found to increase from 0.6 to 1.0/cm, and to be accompanied by significant band shape changes. When used to further constrain the Baines and Bergstrahl (1986) standard model of the Uranus atmosphere, the low-temperature data yield an excellent fit to the bandshape near the 6190 A band's minimum. 18 refs.

  17. Effects of combined scattering and absorption coefficients on laser speckle contrast imaging values

    NASA Astrophysics Data System (ADS)

    Khaksari, Kosar; Kirkpatrick, Sean J.

    2015-03-01

    Laser Speckle contrast imaging (LSCI) is a non-invasive or minimally invasive method for visualizing blood flow and perfusion in biological tissues. In LSCI the motion of scattering particles results in a reduction in global and regional speckle contrast. A variety of parameters can affect the calculated contrast values in LSCI techniques, including the optical properties of the fluid and surrounding tissue. In typical LSCI where the motion of blood is of interests, optical properties are influenced by hematocrit levels. In this work we considered the combined effects of both the scattering and absorption coefficients on LSCI measurements on a flow phantom. Fluid phantoms consisting of various concentrations of neutrally buoyant ~10 micron microspheres and India ink mixed with DI water were formulated to mimic the optical properties of whole blood with various levels of hematocrit. In these flow studies, it was found that an increase in μa and/or μs led to a decrease in contrast values when all other experimental parameters were held constant. The observed reduction in contrast due to optical property changes could easily be confused with a contrast reduction due to increased flow velocity. These results suggest that optical properties need to be considered when using LSCI to make flow estimates.

  18. Optoelectronic properties of Mg{sub 2}Si semiconducting layers with high absorption coefficients

    SciTech Connect

    Kato, Takashi; Sago, Yuichiro; Fujiwara, Hiroyuki

    2011-09-15

    In an attempt to develop a low-cost material for solar cell devices, polycrystalline magnesium silicide (poly-Mg{sub 2}Si) semiconducting layers have been prepared by applying rf magnetron sputtering using a Mg{sub 2}Si target. The optimum substrate temperature for the poly-Mg{sub 2}Si growth was found to be T{sub s} = 200 deg. C; the film deposition at higher temperatures leads to desorption of Mg atoms from the growing surface, while the amorphous phase formation occurs at room temperature. The poly-Mg{sub 2}Si layer deposited at T{sub s} = 200 deg. C shows the (111) preferential orientation with a uniform grain size of {approx}50 nm. The dielectric function of the poly-Mg{sub 2}Si layer has been determined accurately by spectroscopic ellipsometry. From the analysis, quite high absorption coefficients and an indirect gap of 0.77 eV in the poly-Mg{sub 2}Si layer have been confirmed. The above poly-Mg{sub 2}Si layer shows clear photoconductivity and can be applied as a narrow-gap bottom layer in multi-junction solar cell devices.

  19. Noise-driven optical absorption coefficients of impurity doped quantum dots

    NASA Astrophysics Data System (ADS)

    Ganguly, Jayanta; Saha, Surajit; Pal, Suvajit; Ghosh, Manas

    2016-01-01

    We make an extensive investigation of linear, third-order nonlinear, and total optical absorption coefficients (ACs) of impurity doped quantum dots (QDs) in presence and absence of noise. The noise invoked in the present study is a Gaussian white noise. The quantum dot is doped with repulsive Gaussian impurity. Noise has been introduced to the system additively and multiplicatively. A perpendicular magnetic field acts as a source of confinement and a static external electric field has been applied. The AC profiles have been studied as a function of incident photon energy when several important parameters such as optical intensity, electric field strength, magnetic field strength, confinement energy, dopant location, relaxation time, Al concentration, dopant potential, and noise strength take on different values. In addition, the role of mode of application of noise (additive/multiplicative) on the AC profiles has also been analyzed meticulously. The AC profiles often consist of a number of interesting observations such as one photon resonance enhancement, shift of AC peak position, variation of AC peak intensity, and bleaching of AC peak. However, presence of noise alters the features of AC profiles and leads to some interesting manifestations. Multiplicative noise brings about more complexity in the AC profiles than its additive counterpart. The observations indeed illuminate several useful aspects in the study of linear and nonlinear optical properties of doped QD systems, specially in presence of noise. The findings are expected to be quite relevant from a technological perspective.

  20. Effects of nanosilver on sound absorption coefficients in solid wood species.

    PubMed

    Taghiyari, Hamid Reza; Esmailpour, Ayoub; Zolfaghari, Habib

    2016-06-01

    Sound absorption coefficients (ACs) were determined in five solid woods (poplar, beech, walnut, mulberry, and fir) in the longitudinal and tangential directions at four different frequencies of 800, 1000, 2000, and 4000 Hz. The length of the longitudinal and tangential specimens was 50-mm and 10-mm, respectively. Separate sets of specimens were impregnated with either nanosilver suspension or water. The size range of nanoparticles was 30-80 nm. Results showed that sound ACs were lower in longitudinal specimens because sound waves could penetrate the open ends of vessels more easily, being trapped and damped there. Impregnation with both nanosilver suspension and water resulted in a significant decrease in the sound ACs. The decrease in the ACs was due to the collapsing and accumulation of perforation plates and cell parts, blocking the way through which waves could pass through the vessels. This caused higher damping due to a phenomenon called vibration decay. Correlation between gas permeability versus sound AC is significantly dependant on the porous structure of individual specimens.

  1. Linear absorption coefficient of beryllium in the 50-300-A wavelength range. [bandpass filter materials for ultraviolet astronomy instrumentation

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Lewis, M.; Petre, R.

    1983-01-01

    Transmittances of thin-film filters fabricated for an extreme-UV astronomy sounding-rocket experiment yield values for the linear absorption coefficient of beryllium in the 50-300-A wavelength range, in which previous measurements are sparse. The inferred values are consistent with the lowest data previously published and may have important consequences for extreme-UV astronomers.

  2. Effect of absorption parameters on calculation of the dose coefficient: example of classification of industrial uranium compounds.

    PubMed

    Chazel, V; Houpert, P; Paquet, F; Ansoborlo, E

    2001-01-01

    In the Human Respiratory Tract Model (HRTM) described in ICRP Publication 66, time-dependent dissolution is described by three parameters: the fraction dissolved rapidly, fr, and the rapid and slow dissolution rates sr and ss. The effect of these parameters on the dose coefficient has been studied. A theoretical analysis was carried out to determine the sensitivity of the dose coefficient to variations in the values of these absorption parameters. Experimental values of the absorption parameters and the doses per unit intake (DPUI) were obtained from in vitro dissolution tests, or from in vivo experiments with rats, for five industrial uranium compounds UO2, U3O8, UO4, UF4 and a mixture of uranium oxides. These compounds were classified in terms of absorption types (F, M or S) according to ICRP. The overall result was that the factor which has the greatest influence on the dose coefficient was the slow dissolution rate ss. This was verified experimentally, with a variation of 20% to 55% for the DPUI according to the absorption type of the compound. In contrast, the rapid dissolution rate sr had little effect on the dose coefficient, excepted for Type F compounds.

  3. ABSORBANCE, ABSORPTION COEFFICIENT, AND APPARENT QUANTUM YIELD: A COMMENT ON AMBIGUITY IN THE USE OF THESE OPTICAL CONCEPTS

    EPA Science Inventory

    Several important optical terms such as "absorbance" and "absorption coefficient" are frequently used ambiguously in the current peer-reviewed literature. Since they are important terms that are required to derive other quantities such as the "apparent quantum yield" of photoprod...

  4. Influence of plasma parameters on the absorption coefficient of alpha particles to lower hybrid waves in tokamaks

    SciTech Connect

    Wang, J.; Zhang, X. Yu, L.; Zhao, X.

    2014-12-15

    In tokamaks, fusion generated α particles may absorb lower hybrid (LH) wave energy, thus reducing the LH current drive efficiency. The absorption coefficient γ{sub α} of LH waves due to α particles changing with some typical parameters is calculated in this paper. Results show that γ{sub α} increases with the parallel refraction index n{sub ‖}, while decreases with the frequency of LH waves ω over a wide range. Higher background plasma temperature and toroidal magnetic field will increase the absorption. The absorption coefficient γ{sub α} increases with n{sub e} when n{sub e} ≤ 8 × 10{sup 19} m{sup −3}, while decreases with n{sub e} when n{sub e} becomes larger, and there is a peak value of γ{sub α} when n{sub e} ≈ 8 × 10{sup 19} m{sup −1} for the ITER-like scenario. The influence of spectral broadening in parametric decay instabilities on the absorption coefficient is evaluated. The value of γ{sub α} with n{sub ‖} being 2.5 is almost two times larger than that with n{sub ‖} being 2.0 and is even lager in the case of 2.9, which will obviously increase the absorption of the LH power by alpha particles.

  5. Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry.

    PubMed

    Benmakhlouf, Hamza; Bouchard, Hugo; Fransson, Annette; Andreo, Pedro

    2011-11-21

    Backscatter factors, B, and mass energy-absorption coefficient ratios, (μ(en)/ρ)(w, air), for the determination of the surface dose in diagnostic radiology were calculated using Monte Carlo simulations. The main purpose was to extend the range of available data to qualities used in modern x-ray techniques, particularly for interventional radiology. A comprehensive database for mono-energetic photons between 4 and 150 keV and different field sizes was created for a 15 cm thick water phantom. Backscattered spectra were calculated with the PENELOPE Monte Carlo system, scoring track-length fluence differential in energy with negligible statistical uncertainty; using the Monte Carlo computed spectra, B factors and (μ(en)/ρ)(w, air) were then calculated numerically for each energy. Weighted averaging procedures were subsequently used to convolve incident clinical spectra with mono-energetic data. The method was benchmarked against full Monte Carlo calculations of incident clinical spectra obtaining differences within 0.3-0.6%. The technique used enables the calculation of B and (μ(en)/ρ)(w, air) for any incident spectrum without further time-consuming Monte Carlo simulations. The adequacy of the extended dosimetry data to a broader range of clinical qualities than those currently available, while keeping consistency with existing data, was confirmed through detailed comparisons. Mono-energetic and spectra-averaged values were compared with published data, including those in ICRU Report 74 and IAEA TRS-457, finding average differences of 0.6%. Results are provided in comprehensive tables appropriated for clinical use. Additional qualities can easily be calculated using a designed GUI interface in conjunction with software to generate incident photon spectra.

  6. Specific absorption coefficient and phytoplankton biomass in the southern region of the California Current

    NASA Astrophysics Data System (ADS)

    Millán-Núñez, Eduardo; Sieracki, Michael E.; Millán-Núñez, Roberto; Lara-Lara, José Rubén; Gaxiola-Castro, Gilberto; Trees, Charles C.

    2004-03-01

    In recent years, experts of optical hydrology have shown great interest in the variability of the specific absorption coefficient of light by phytoplankton (aph*). This parameter is important and necessary for comparing in situ bio-optical and satellite optical measurements. Such comparisons are needed for detecting primary productivity at a mesoscale level. At present, however, the parameters used in algorithms for predicting productivity are global averages. To avoid this bias, we measured the spatial-temporal variability of aph* as part of the Jan-01 Investigaciones Mexicanas de la Corriente de California cruise along the southern California Current. We observed median values of 0.041 m2 (mg chlorophyll a (Chl a))-1 at 440 nm and 0.015 at 674 nm, with significant differences between inshore and offshore stations. In general, the stations located in the area of Bahía Vizcaíno, with oceanographic conditions favorable for the growth of phytoplankton, showed lower values of the aph* . The nano-microphytoplankton (>5 μm) community comprised of 26 diatom genera with mean abundance values of the 19.5×103 cells l-1. Nitzschia closterium, a pennate diatom, was almost uniform throughout the study region. Flow cytometry measurements indicated that the picoplankton (<5 μm) community consisted of two prokaryotes, Prochlorococcus (mean 3.6×106 cells l-1) and Synechococcus (mean 10.4×106 cells l-1), and a mixture of picoeukaryotes (mean 6.5×106 cells l-1). Analyses of Chl and carotenoid pigments determined by high-performance liquid chromatographic confirmed the presence of the divinyl Chl a characteristic of Prochlorococcus. The nano-micro- and picoplankton were 82% and 18% of total phytoplankton biomass (μg C l-1), respectively. In general, we concluded that the phytoplankton community structure and biomass on this cruise showed conditions similar to oligotrophic systems.

  7. A reduced-scale railway noise barrier's insertion loss and absorption coefficients: comparison of field measurements and predictions

    NASA Astrophysics Data System (ADS)

    Busch, T. A.; Nugent, R. E.

    2003-10-01

    In situ testing determined the insertion loss ( IL) and absorption coefficients of a candidate absorptive noise barrier (soundwall) to abate railway noise for residents of Anaheim, CA. A 4000 m barrier is proposed south of the tracks, but residential areas to the north have expressed concerns that barrier reflections will increase their noise exposure. To address these concerns, a 3.66 m high by 14.6 m long demonstration barrier was built in the parking lot of Edison Field, Anaheim, as part of a public open house, thereby allowing for acoustical measurements. Insertion loss ( IL) was measured in third-octave bands assuming 1/2-scale construction. The IL for three, scaled railway noise sub-sources (rail/wheel interface, locomotive, and train horn) was measured at six, scaled distances. The highest total, A-weighted IL, after corrections for finite-barrier and point-source speaker effects was 22 dB(A) for rail/wheel noise, 18 dB(A) for locomotive noise, and 20 dB(A) for train horn noise. These results can be compared favourably to IL predictions made using algorithms from the US Federal Rail Administration (FRA) noise assessment guidelines. For the actual barrier installation, shielded residential receivers located south of the project are expected to see their future noise exposures reduced from an unmitigated 78 CNEL to 65 CNEL. Absorption coefficients were measured using time delay spectrometry. At lower frequencies, measured absorption coefficients were notably less than the reverberation room results advertised in the manufacturer's literature, but generally conformed with impedance tube results. At higher frequencies the correspondence between measured absorption coefficients and reverberation room results was much improved. For the actual barrier installation, unshielded residential receivers to the north are expected to experience noise exposure increases of less than 1 dB(A). This factor of increase is consistent with a finding of no impact when assessed

  8. [Experimental determination of radiation scattering and absorption coefficients in a homogeneous layer of highly-dispersive biological medium].

    PubMed

    Danilov, A A; Masloboev, Iu P; Selishchev, S V; Tereshchenko, S A

    2006-01-01

    A method for experimental determination of optical characteristics of a highly-dispersive medium (radiation scattering and absorption coefficients) is described. The method is based on two mathematical models of ultrashort laser pulse propagation through a highly-dispersive medium (HDM), an axial model and a diffusion model. Milk dissolved in water was used as HDM. Dependences of optical characteristics of HDM on the concentration of milk in water are obtained. The limits of applicability of the axial and diffusion models to media with different scattering and absorption characteristics are determined.

  9. The absorption coefficient of the liquid N2 2.15-micron band and application to Triton

    NASA Technical Reports Server (NTRS)

    Grundy, William M.; Fink, Uwe

    1991-01-01

    The present measurements of the temperature dependence exhibited by the liquid N2 2.15-micron 2-0 collision-induced band's absorption coefficient and integrated absorption show the latter to be smaller than that of the N2 gas, and to decrease with decreasing temperature. Extrapolating this behavior to Triton's nominal surface temperature yields a new estimate of the N2-ice grain size on the Triton south polar cap; a mean N2 grain size of 0.7-3.0 cm is consistent with grain growth rate calculation results.

  10. Influence of the scattering and absorption coefficients on homogeneous room simulations that use a diffusion equation model.

    PubMed

    Navarro, Juan M; Escolano, José; Cobos, Maximo; López, José J

    2013-03-01

    The diffusion equation model was used for room acoustic simulations to predict the sound pressure level and the reverberation time. The technical literature states that the diffusion equation method accurately models the late portion of the room impulse response if the energy is sufficiently scattered. This work provides conclusions on the validity of the diffusion equation model for rooms with homogeneous dimensions in relation to the scattering coefficients of the boundaries. A systematic evaluation was conducted out to determine the ranges of the absorption and scattering coefficient values that result in low noticeable differences between the predictions from a geometrical acoustic model and those from the diffusion equation model.

  11. Characterizing the Chlorophyll-a Specific Absorption Coefficient of Phytoplankton Measured in the Gulf of Maine in Varying Oceanic Provinces

    NASA Astrophysics Data System (ADS)

    Dowell, M.

    2006-12-01

    Chlorophyll-a specific absorption (aph*) is a parameter used in bio-optical and primary production models and its coefficients are usually assumed to be constant. However, it has been documented in previous studies that these coefficients vary significantly due to pigmentation and "the package effect" which are a function of the taxonomic composition and the physiological state of the algal population. As part of the Coastal Ocean Observing Center (COOC) at the University of New Hampshire, HPLC pigments and phytoplankton absorption measurements were taken from water samples collected within the Gulf of Maine from 2004-2006. These data were then partitioned spatially, temporally, seasonally, and by other classification criteria. Spectral aph* means were generated for all partitions within each classification method. The results were used to parameterize province-specific bio-optical models for a regional algorithm. The separation of aph* means into different classes captured the effects of taxonomy and the package effect by reducing aph* variability.

  12. Absorption coefficients of CFC-11 and CFC-12 needed for atmospheric remote sensing and global warming studies

    NASA Technical Reports Server (NTRS)

    Varanasi, Prasad

    1992-01-01

    Spectral absorption coefficients k(v) in the atmospheric window are reported for CFC-11 and CFC-12. Data obtained with a grating spectrometer are compared with NCAR cross sections and measurements of k(v) made with a tunable diode laser spectrometer at various temperature-pressure combinations representing tangent heights or layers in the atmosphere are presented. The results are suitable for atmospheric remote sensing and global warming studies.

  13. Additions and corrections to the absorption coefficients of CO2 ice - Applications to the Martian south polar cap

    NASA Technical Reports Server (NTRS)

    Calvin, Wendy M.

    1990-01-01

    Reflectance spectra of carbon dioxide frosts were calculated using the optical constants provided by Warren (1986) for the wavelength region 2-6 microns. In comparing these calculated spectra to spectra of frosts observed in the laboratory and on the surface of Mars, problems in the optical constants presented by Warren (1986) became apparent. Absorption coefficients for CO2 ice have been derived using laboratory reflectance measurements and the Hapke (1981) model for calculating diffuse reflectance. This provides approximate values in regions where no data were previously available and indicates where corrections to the compilation by Warren (1986) are required. Using these coefficients to calculate the reflectance of CO2 ice at varying grain sizes indicates that a typical Mariner polar cap spectrum is dominated by absorptions due to CO2 frost or ice at grain sizes that are quite large, probably of the order of millimeters to centimeters. There are indications of contamination of water frost or dust, but confirmation will require more precise absorption coefficients for solid CO2 than can be obtained from the method used here.

  14. The absorption of trapped particles by the inner satellites of Jupiter and the radial diffusion coefficient of particle transport

    NASA Technical Reports Server (NTRS)

    Mogro-Campero, A.; Fillius, W.

    1976-01-01

    The process of trapped particle absorption by the inner Jovian satellites is considered in detail taking into account both the particle and satellite motions in a magnetic dipole field which is displaced from the center of the planet and tilted with respect to the planetary rotation axis. An expression is derived for computing the sweeping time at a given satellite, defined as the time required for the satellite to sweep up a given fraction of the trapped particles within its sweeping region. By making use of the sweeping time and the radial diffusion equation of particle transport approximate expressions for the diffusion coefficient are derived. Measurements obtained by Pioneer 10 are then used to obtain estimates of the diffusion coefficient at the orbits of Io and Europa. We find that the diffusion coefficient is a function of energy and magnetic latitude for electrons in the energy range 0.7-14 MeV.

  15. Absorption coefficient modeling of microcrystalline silicon thin film using Maxwell-Garnett effective medium theory.

    PubMed

    Chen, Sheng-Hui; Wang, Hsuan-Wen; Chang, Ting-Wei

    2012-03-12

    Considering the Mott-Davis density of state model and Rayleigh scattering effect, we present an approach to model the absorption profile of microcrystalline silicon thin films in this paper. Maxwell-Garnett effective medium theory was applied to analyze the absorption curves. To validate the model, several experimental profiles have been established and compared with those results from the model. With the assistance of the genetic algorithm, our results show that the absorption curves from the model are in good agreement with the experiments. Our findings also indicate that, as the crystal volume fraction increases, not only do the defects in amorphous silicon reduce, but the bulk scattering effect is gradually enhanced as well.

  16. Simultaneous Maximum-Likelihood Reconstruction of Absorption Coefficient, Refractive Index and Dark-Field Scattering Coefficient in X-Ray Talbot-Lau Tomography

    PubMed Central

    Ritter, André; Anton, Gisela; Weber, Thomas

    2016-01-01

    A maximum-likelihood reconstruction technique for X-ray Talbot-Lau tomography is presented. This technique allows the iterative simultaneous reconstruction of discrete distributions of absorption coefficient, refractive index and a dark-field scattering coefficient. This technique avoids prior phase retrieval in the tomographic projection images and thus in principle allows reconstruction from tomographic data with less than three phase steps per projection. A numerical phantom is defined which is used to evaluate convergence of the technique with regard to photon statistics and with regard to the number of projection angles and phase steps used. It is shown that the use of a random phase sampling pattern allows the reconstruction even for the extreme case of only one single phase step per projection. The technique is successfully applied to measured tomographic data of a mouse. In future, this reconstruction technique might also be used to implement enhanced imaging models for X-ray Talbot-Lau tomography. These enhancements might be suited to correct for example beam hardening and dispersion artifacts and improve overall image quality of X-ray Talbot-Lau tomography. PMID:27695126

  17. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    SciTech Connect

    Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hueller, S.

    2005-03-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path {lambda}{sub ei} compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter {lambda}{sub ei}/L.

  18. Uranyl ion: A convenient standard for transient molar absorption coefficient measurements

    SciTech Connect

    Bakac, A.; Burrows, H.D.

    1997-12-01

    Transient absorption spectra of an aqueous solution of uranyl sulfate have been measured in the ultraviolet and visible spectra. The excited uranyl ion may be a convenient standard for actinometry and photoacoustic calorimetry. (AIP) {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  19. Intersubband transition in lattice-matched BGaN/AlN quantum well structures with high absorption coefficients.

    PubMed

    Park, Seoung-Hwan; Ahn, Doyeol; Park, Chan-Yong

    2017-02-20

    Intersubband absorption properties of lattice-matched BGaN/AlN quantum well (QW) structures grown on AlN substrate are theoretically investigated using an effective mass theory considering the nonparabolicity of the conduction band. These results are compared with those of GaN/AlN QW structures. The intersubband absorption coefficient of the BGaN/AlN QW structure is shown to be enhanced significantly, compared to that of the conventional GaN/AlN QW structure. This can be explained by the fact that the BGaN/AlN QW structure exhibits larger intersuband dipole moment and quasi-Fermi-level separation than the GaN/AlN QW structure, due to the increase in the carrier confinement by a larger internal field. We expect that the BGaN/AlN QW structure with a high absorption coefficient can be used for telecommunication applications at 1.55 µm under the lattice-matched condition, instead of the conventional GaN/AlN QW structure with the large strain.

  20. Spatial variability of absorption coefficients over a biogeochemical gradient in a large and optically complex shallow lake

    NASA Astrophysics Data System (ADS)

    Riddick, Caitlin A. L.; Hunter, Peter D.; Tyler, Andrew N.; Martinez-Vicente, Victor; Horváth, Hajnalka; Kovács, Attila W.; Vörös, Lajos; Preston, Tom; Présing, Mátyás.

    2015-10-01

    In order to improve robustness of remote sensing algorithms for lakes, it is vital to understand the variability of inherent optical properties (IOPs) and their mass-specific representations (SIOPs). In this study, absorption coefficients for particulate and dissolved constituents were measured at 38 stations distributed over a biogeochemical gradient in Lake Balaton, Hungary. There was a large range of phytoplankton absorption (aph(λ)) over blue and red wavelengths (aph(440) = 0.11-4.39 m-1, aph(675) = 0.048-2.52 m-1), while there was less variability in chlorophyll-specific phytoplankton absorption (a*ph(λ)) in the lake (a*ph(440) = 0.022 ± 0.0046 m2 mg-1, a*ph(675) = 0.010 ± 0.0020 m2 mg-1) and adjoining wetland system, Kis-Balaton (a*ph(440) = 0.017 ± 0.0015 m2 mg-1, a*ph(675) = 0.0088 ± 0.0017 m2 mg-1). However, in the UV, a*ph(350) significantly increased with increasing distance from the main inflow (Zala River). This was likely due to variable production of photoprotective pigments (e.g., MAAs) in response to the decreasing gradient of colored dissolved organic matter (CDOM). The slope of CDOM absorption (SCDOM) also increased from west to east due to larger terrestrial CDOM input in the western basins. Absorption by nonalgal particles (aNAP(λ)) was highly influenced by inorganic particulates, as a result of the largely mineral sediments in Balaton. The relative contributions to the absorption budget varied more widely than oceans with a greater contribution from NAP (up to 30%), and wind speed affected the proportion attributed to NAP, phytoplankton, or CDOM. Ultimately, these data provide knowledge of the heterogeneity of (S)IOPs in Lake Balaton, suggesting the full range of variability must be considered for future improvement of analytical algorithms for constituent retrieval in inland waters.

  1. The Optical Absorption Coefficient of Barley Seeds Investigated by Photoacoustic Spectroscopy and Their Effects by Laser Biostimulation

    NASA Astrophysics Data System (ADS)

    Pérez Reyes, Ma. C.; Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.; Moreno Martínez, E.

    2015-09-01

    Laser light as a biostimulator has been applied in agriculture, and some scientific reports evidence its usefulness. A knowledge about seed optical parameters is of great relevance in the biostimulation process, because information can be provided about the light absorption of seeds. Thus, the objective of the present study was to determine the optical absorption coefficient (β ) of barley ( Hordeum vulgare L.) seeds by means of photoacoustic spectroscopy; these seeds were studied in two conditions: seeds in their natural color and seeds dyed with methylene blue. The seeds were biostimulated by a laser beam (650 nm wavelength) to evaluate the effects of pre-sowing biostimulation in natural mycobiota associated with different laser irradiation times (0 s, 60 s, 120 s, 240 s, and 480 s). The results of this research demonstrated changes in the optical parameters (absorption and penetration) that occur in the seeds by changing the natural condition to a dyed condition. The dyed seeds, by the methylene blue photosensitizer, become optically opaque, producing greater optical absorption at 650 nm which causes an increase in the effect of laser stimulation. The experimental results showed that the biggest mycobiota reduction (52 %) corresponded to dyed seeds irradiated with a laser for 120 s.

  2. Specific absorption and backscatter coefficient signatures in southeastern Atlantic coastal waters

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R., Jr.

    1998-12-01

    Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Florida. Stations were also occupied in near coastal waters out to the edge of the Gulf Stream in the vicinity of Kennedy Space Center, Florida and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting optical cross section signatures suggest different models are needed for the different water types and that the common linear model may only appropriate for coastal and oceanic water types. Mean particle size estimates based on the optical cross section, suggest as expected, that particle size of oceanic particles are smaller than more turbid water types. The data discussed and presented are necessary for remote sensing applications of sensors as well as for development and inversion of remote sensing algorithms.

  3. Using high-resolution laboratory and ground-based solar spectra to assess CH4 absorption coefficient calculations

    NASA Astrophysics Data System (ADS)

    Mendonca, J.; Strong, K.; Sung, K.; Devi, V. M.; Toon, G. C.; Wunch, D.; Franklin, J. E.

    2017-03-01

    A quadratic-speed-dependent Voigt line shape (qSDV) with line mixing (qSDV+LM), together with spectroscopic line parameters from Devi et al. [1,2] for the 2v3 band of CH4, was used to retrieve total columns of CH4 from atmospheric solar absorption spectra. The qSDV line shape (Tran et al., 2013) [3] with line mixing (Lévy et al., 1992) [4] was implemented into the forward model of GFIT (the retrieval algorithm that is at the heart of the GGG software (Wunch et al., 2015) [5]) to calculate CH4 absorption coefficients. High-resolution laboratory spectra of CH4 were used to assess absorption coefficients calculated using a Voigt line shape and spectroscopic parameters from the atm line list (Toon, 2014) [6]. The same laboratory spectra were used to test absorption coefficients calculated using the qSDV+LM line shape with spectroscopic line parameters from Devi et al. [1,2] for the 2v3 band of CH4 and a Voigt line shape for lines that don't belong to the 2v3 band. The spectral line list for lines that don't belong to the 2v3 band is an amalgamation of multiple spectral line lists. We found that for the P, Q, and R branches of the 2v3 band, the qSDV+LM simulated the laboratory spectra better than the Voigt line shape. The qSDV+LM was also used in the spectral fitting of high-resolution solar absorption spectra from four ground-based remote sensing sites and compared to spectra fitted with a Voigt line shape. The average root mean square (RMS) residual for 131,124 solar absorption spectra fitted with absorption coefficients calculated using the qSDV+LM for the 2v3 band of CH4 and the new spectral line list for lines for lines that don't belong to the 2v3 band, was reduced in the P, Q, and R branches by 5%, 13%, and 3%, respectively when compared with spectra fitted using a Voigt line shape and the atm line list. We found that the average total column of CH4 retrieved from these 131,124 spectra, with the qSDV+LM was 1.1±0.3% higher than the retrievals performed using a

  4. Effect of quantum dot size and size distribution on the intersublevel transitions and absorption coefficients of III-V semiconductor quantum dot

    SciTech Connect

    Kabi, Sanjib; Perera, A. G. Unil

    2015-03-28

    The intersublevel absorption peak energy and absorption coefficient of non-uniform quantum dot (QD) ensembles are calculated analytically. The effect of size variations and size distribution of QDs on their energy states is analyzed. The dots are considered as a quantum box with finite potential at the barriers and the size distribution described by a Gaussian function. The influence of the aspect ratio (base to height ratio) of the QDs on the optical transitions is studied. Our model predicts the dot size (height and base) accurately to determine the absorption peaks and corresponding absorption coefficient. We also compute the absorption coefficient of the QD with different size distributions to verify the results calculated using this model with the reported experimental and other theoretical results.

  5. Effects of magnetic field and the built-in internal fields on the absorption coefficients in a strained wurtzite GaN/AlGaN quantum dot

    NASA Astrophysics Data System (ADS)

    Minimala, N. S.; Peter, A. John

    2013-02-01

    Effects of magnetic field strength and the built-in electric fields on the exciton binding energy and the non-linear optical property such as absorption coefficients in a GaN/AlGaN wide band gap heterostructure are investigated. The internal fields due to spontaneous and piezo-electric polarizations are included in the Hamiltonian. Our results show that the optical absorption coefficients strongly depend on the internal fields and the applied magnetic field.

  6. Changing of optical absorption and scattering coefficients in nonlinear-optical crystal lithium triborate before and after interaction with UV-radiation

    NASA Astrophysics Data System (ADS)

    Demkin, Artem S.; Nikitin, Dmitriy G.; Ryabushkin, Oleg A.

    2016-04-01

    In current work optical properties of LiB3O5 (LBO) crystal with ultraviolet (UV) (λ= 266 nm) induced volume macroscopic defect (track) are investigated using novel piezoelectric resonance laser calorimetry technique. Pulsed laser radiation of 10 W average power at 532 nm wavelength, is consecutively focused into spatial regions with and without optical defect. For these cases exponential fitting of crystal temperature kinetics measured during its irradiation gives different optical absorption coefficients α1 = 8.1 • 10-4 cm-1 (region with defect) and α =3.9ṡ10-4 cm-1 (non-defected region). Optical scattering coefficient is determined as the difference between optical absorption coefficients measured for opaque and transparent lateral facets of the crystal respectively. Measurements reveal that scattering coefficient of LBO in the region with defect is three times higher than the optical absorption coefficient.

  7. Determination of scattering coefficient considering wavelength and absorption dependence of anisotropy factor measured by polarized beam for biological tissues

    NASA Astrophysics Data System (ADS)

    Fukutomi, D.; Ishii, K.; Awazu, K.

    2015-12-01

    Anisotropy factor g, one of the optical properties of biological tissues, is the most important parameter to accurately determine scattering coefficient μs in the inverse Monte Carlo (iMC) simulation. It has been reported that g has wavelength and absorption dependence, however, there are few attempts in order to calculate μs of biological tissue considering the wavelength and absorption dependence of g. In this study, the scattering angular distributions of biological tissue phantoms were measured in order to determine g by using goniometric measurements with three polarization conditions at strongly and weakly absorbing wavelengths of hemoglobin. Then, optical properties, especially, μs were measured by integrating sphere measurements and iMC simulation in order to confirm the influence of measured g on optical properties in comparison of with general value of g (0.9) for soft biological tissue. Consequently, it was found that μs was overestimated at strongly absorbing wavelength, however, μs was underestimated at weakly absorbing wavelength if the g was not considered its wavelength and absorption dependence.

  8. Field calibration of multi-scattering correction factor for aethalometer aerosol absorption coefficient during CAPMEX Campaign, 2008

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Kim, S. W.; Yoon, S. C.; Park, R.; Ogren, J. A.

    2014-12-01

    Filter-based instrument, such as aethalometer, is being widely used to measure equivalent black carbon(EBC) mass concentration and aerosol absorption coefficient(AAC). However, many other previous studies have poited that AAC and its aerosol absorption angstrom exponent(AAE) are strongly affected by the multi-scattering correction factor(C) when we retrieve AAC from aethalometer EBC mass concentration measurement(Weingartner et al., 2003; Arnott et al., 2005; Schmid et al., 2006; Coen et al., 2010). We determined the C value using the method given in Weingartner et al. (2003) by comparing 7-wavelngth aethalometer (AE-31, Magee sci.) to 3-wavelength Photo-Acoustic Soot Spectrometer (PASS-3, DMT) at Gosan climate observatory, Korea(GCO) during Cheju ABC plume-asian monsoon experiment(CAPMEX) campaign(August and September, 2008). In this study, C was estimated to be 4.04 ± 1.68 at 532 nm and AAC retrieved with this value was decreased as approximately 100% as than that retrieved with soot case value from Weingartner et al (2003). We compared the AAC determined from aethalomter measurements to that from collocated Continuous Light Absorption Photometer (CLAP) measurements from January 2012 to December 2013 at GCO and found good agreement in both AAC and AAE. This result suggests the determination of site-specific C is crucially needed when we calculate AAC from aethalometer measurements.

  9. Photoinduced transparency of effective three-photon absorption coefficient for femtosecond laser pulses in Ge16As29Se55 thin films

    NASA Astrophysics Data System (ADS)

    Barik, A. R.; Adarsh, K. V.; Naik, Ramakanta; Sandeep, C. S. Suchand; Philip, Reji; Zhao, Donghui; Jain, Himanshu

    2011-05-01

    We report a dramatic change in effective three-photon absorption coefficient of amorphous Ge16As29Se55 thin films, when its optical band gap decreases by 10 meV with 532 nm light illumination. This large change provides valuable information on the higher excited states, which are otherwise inaccessible via normal optical absorption. The results also indicate that photodarkening in chalcogenide glasses can serve as an effective tool to tune the multiphoton absorption in a rather simple way.

  10. Impact of measurement uncertainties on determination of chlorophyll-specific absorption coefficient for marine phytoplankton

    NASA Astrophysics Data System (ADS)

    McKee, David; Röttgers, Rüdiger; Neukermans, Griet; Calzado, Violeta Sanjuan; Trees, Charles; Ampolo-Rella, Marina; Neil, Claire; Cunningham, Alex

    2014-12-01

    Understanding variability in the chlorophyll-specific absorption of marine phytoplankton, aph*Chl (λ), is essential for primary production modelling, calculation of underwater light field characteristics, and development of algorithms for remote sensing of chlorophyll concentrations. Previous field and laboratory studies have demonstrated significant apparent variability in aph*Chl (λ) for natural samples and algal cultures. However, the potential impact of measurement uncertainties on derived values of aph*Chl (λ) has received insufficient study. This study presents an analysis of measurement uncertainties for a data set collected in the Ligurian Sea in Spring and assesses the impact on estimates of aph*Chl (λ). It is found that a large proportion of apparent variability in this set of aph*Chl (λ) can be attributed to measurement errors. Application of the same analysis to the global NOMAD data set suggests that a significant fraction of variability in aph*Chl (λ) may also be due to measurement errors. The copyright line for this article was changed on 16 JAN 2015 after original online publication.

  11. Effects of suspended sediment concentration on the absorption and scattering coefficients

    NASA Astrophysics Data System (ADS)

    Terrie, Gregory E.; Ladner, Sherwin; Gould, Richard A., Jr.

    1997-02-01

    The scattering coefficient (b) for the nearshore waters off the coast of North Carolina near Camp Lejeune is strongly influenced by suspended sediment concentration and total particulate cross-sectional area (xg). In-situ measurements of a and b were made using a WET Labs AC9 meter. Estimates of suspended sediment concentration and total particulate cross-sectional area were determined from laser particle size analyses of surface water samples. The SeaWiFS bio-optical algorithm was modified for Case II waters and used to estimate a and bb from remote sensing reflectance (Rrs). After conversion from backscattering (bb) to total scattering (b), modeled a and b values from the modified SeaWiFS algorithm were compared to the measured values. The differences between the measured and estimated values appear to be directly related to increases in suspended sediment concentration and xg. Correlations of about 0.90 were obtained for b vs xg and bb vs xg.

  12. A time-resolved single-pass technique for measuring optical absorption coefficients of window materials under 100 GPa shock pressures.

    PubMed

    Li, Jun; Zhou, Xianming; Li, Jiabo

    2008-12-01

    An experimental method was developed to perform time-resolved, single-pass optical absorption measurements and to determine absorption coefficients of window materials under strong shock compression up to approximately 200 GPa. Experimental details are described of (i) a configuration to generate an in situ dynamic, bright, optical source and (ii) a sample assembly with a lithium fluoride plate to essentially eliminate heat transfer from the hot radiator into the specimen and to maintain a constant optical source within the duration of the experiment. Examples of measurements of optical absorption coefficients of several initially transparent single crystal materials at high shock pressures are presented.

  13. Effect of the concentration of magnetic grains on the linear-optical-absorption coefficient of ferrofluid-doped lyotropic mesophases: deviation from the Beer-Lambert law.

    PubMed

    Cuppo, F L S; Gómez, S L; Figueiredo Neto, A M

    2004-04-01

    In this paper is reported a systematic experimental study of the linear-optical-absorption coefficient of ferrofluid-doped isotropic lyotropic mixtures as a function of the magnetic-grains concentration. The linear optical absorption of ferrolyomesophases increases in a nonlinear manner with the concentration of magnetic grains, deviating from the usual Beer-Lambert law. This behavior is associated to the presence of correlated micelles in the mixture which favors the formation of small-scale aggregates of magnetic grains (dimers), which have a higher absorption coefficient with respect to that of isolated grains. We propose that the indirect heating of the micelles via the ferrofluid grains (hyperthermia) could account for this nonlinear increase of the linear-optical-absorption coefficient as a function of the grains concentration.

  14. Determination of the scattering coefficient of biological tissue considering the wavelength and absorption dependence of the anisotropy factor

    NASA Astrophysics Data System (ADS)

    Fukutomi, Daichi; Ishii, Katsunori; Awazu, Kunio

    2016-04-01

    The anisotropy factor g, one of the optical properties of biological tissues, has a strong influence on the calculation of the scattering coefficient μ s in inverse Monte Carlo (iMC) simulations. It has been reported that g has the wavelength and absorption dependence; however, few attempts have been made to calculate μ s using g values by taking the wavelength and absorption dependence into account. In this study, the angular distributions of scattered light for biological tissue phantoms containing hemoglobin as a light absorber were measured by a goniometric optical setup at strongly (405 nm) and weakly (664 nm) absorbing wavelengths to obtain g. Subsequently, the optical properties were calculated with the measured values of g by integrating sphere measurements and an iMC simulation, and compared with the results obtained with a conventional g value of 0.9. The μ s values with measured g were overestimated at the strongly absorbing wavelength, but underestimated at the weakly absorbing wavelength if 0.9 was used in the iMC simulation.

  15. Light absorption coefficient measurement of SOA using a UV-Visible spectrometer connected with an integrating sphere

    NASA Astrophysics Data System (ADS)

    Zhong, Min; Jang, Myoseon

    2011-08-01

    A method for measuring an aerosol light absorption coefficient ( B a) has been developed using a conventional UV-visible spectrometer equipped with an integrating sphere covering a wide range of wavelengths (280-800 nm). The feasibility of the proposed method was evaluated in both the transmittance mode (TUV-IS) and the reflective mode (RUV-IS) using the reference aerosol known for the cross-sectional area. The aerosol was collected on a conventional filter and measured for B a values. The resulting RUV-IS method was applied to measure light absorption of secondary organic aerosol (SOA). SOA was produced through photooxidation of different precursor hydrocarbons such as toluene, d-limonene and α-pinene in the presence of NO x (60-70 ppb) and inorganic seed aerosol using a 2-m 3 indoor Teflon film chamber. Of the three precursor hydrocarbons, the B a value of toluene SOA (0.574 m 2 g -1 at 350 nm) was the highest compared with B a values for α-pinene SOA (0.029 m 2 g -1) and d-limonene SOA (0.038 m 2 g -1). When d-limonene SOA or toluene SOA was internally mixed with neutral [(NH 4) 2SO 4] or acidic inorganic seed (NH 4HSO 4:H 2SO 4 = 1:1 by mole), the SOA showed 2-3 times greater B a values at 350 nm than the SOA with no seed. Aerosol aging with a light source for this study reduced B a values of SOA (e.g., on average 10% for toluene SOA and 30% for d-limonene SOA within 4 h). Overall, weak absorption appeared for chamber-generated SOA over wavelengths ranging from 280 to 550 nm, which fall into the sunlight spectrum.

  16. Decoupling scattering and absorption of turbid samples using a simple empirical relation between coefficients of the Kubelka-Munk and radiative transfer theories.

    PubMed

    Gaonkar, Harshavardhan Ashok; Kumar, Dinesh; Ramasubramaniam, Rajagopal; Roy, Arindam

    2014-05-01

    Efforts are underway to better understand the absorption properties of micro- and nano-sized particles due to their potential in various photonic applications. However, most of these particles exhibit strong scattering in the spectral regions of interest in addition to absorption. Due to strong interference from scattering, the absorption of these turbid samples cannot be directly measured using conventional spectroscopy techniques. The optical properties of these particles are also different from that of the bulk due to quantum confinement and plasmon resonance effects and cannot be inferred from their bulk properties. By measuring the total transmittance and total reflectance (diffuse and collimated) of turbid samples and using an empirical relation between the coefficients of the Kubelka-Munk and radiative transfer theories, we have demonstrated a method to calculate the absorption and reduced scattering coefficients of turbid samples. This method is capable of extracting the absorption coefficient of turbid samples with an error of 2%. Using this method, we have decoupled the specific absorption and specific reduced scattering coefficients of commercially available micro-sized iron oxide particles. The current method can be used to measure the optical properties of irregularly shaped particle dispersions, which are otherwise difficult to estimate theoretically.

  17. Introduction to MAC CRM training

    NASA Technical Reports Server (NTRS)

    Brown, Donald D.

    1987-01-01

    The author introduces the Military Airlift Command (MAC) and its mission. A brief history of Cockpit Resource Management (CRM) as it relates to MAC is given. He also states why MAC is currently interested in CRM.

  18. A method to obtain the absorption coefficient spectrum of single grain coal in the aliphatic C-H stretching region using infrared transflection microspectroscopy.

    PubMed

    Tonoue, Ryota; Katsura, Makoto; Hamamoto, Mai; Bessho, Hiroki; Nakashima, Satoru

    2014-01-01

    A method was developed to obtain the absorption coefficient spectrum of a grain of coal (as small as 10(-7)) in the region of aliphatic and aromatic C-H stretching bands (2700-3200 cm(-1)) using infrared transflection microspectroscopy. In this method, the complex refractive index n - ik was determined using an optimization algorithm with the Kramers-Kronig transform so that the calculated transflection spectrum from the Fresnel equation corresponded to the measured one. The obtained absorption coefficients were compared with the bulk values determined from the potassium bromide (KBr) pellet measurement method.

  19. Quantification of the dynamic changes in the absorption coefficient of liquid water at erbium:YAG and carbon dioxide laser wavelengths

    NASA Astrophysics Data System (ADS)

    Shori, Ramesh K.

    The interaction of high-intensity, short-pulsed radiation with liquid water results in dynamic changes in the optical absorption coefficient of water. These changes and their implications, as related to mid-infrared laser ablation of tissue, were not investigated until the late 1980's and early 1990's. Classical models of absorption and heating do not explain the dynamic, non-linear changes in water. The objective of the present work was to quantify the dynamic changes in the absorption coefficient of liquid water as a function of incident energy at three clinically relevant infrared wavelengths (λ = 2.94, 9.6, 10.6 μm). To investigate the changes in the absorption spectrum of water in the 3-μm band, a stable, high-energy Q- switched Er:YAG laser emitting 2.94-μm radiation in a near-perfect TEMoo spatial beam profile was developed. Key to the development of this laser was careful attention to the gain medium, optical pump system, system optics, and the thermal system. The final system design was capable of emitting 110 mJ/pulse at of 2-4 Hz with a lamp lifetime exceeding 12 million pulses The laser was used in two sets of experiments in order to quantify the above changes. First, the laser was used to measure the velocity of the shock front produced by vaporizing a gelatin-based tissue phantom. The measured shock velocity was related to the optical energy absorbed by the tissue phantom and the absorption coefficient, based on the pressure relationships derived using a 1-D piston model for an expanding plume. The shock front velocity measurements indicate that the absorption coefficient is constant for incident fluences less than 20 J/cm2, a result consistent with transmission data. For higher fluences, the data indicate a decrease in the absorption coefficient, which is again consistent with transmission data. Quantification of the absorption coefficient can, however, not be made without violating assumptions that form the basis for the 1-D piston model. Second

  20. Determination of molar absorptivity coefficients for major type-B trichothecenes and certification of calibrators for deoxynivalenol and nivalenol.

    PubMed

    Krska, Rudolf; Schubert-Ullrich, Patricia; Josephs, Ralf D; Emteborg, Håkan; Buttinger, Gerhard; Pettersson, Hans; van Egmond, Hans P; Schothorst, Ronald C; Macdonald, Susan; Chan, Danny

    2007-07-01

    This paper presents results from the European Commission-funded project Doncalibrant, the objective of which was to produce calibrators with certified mass fractions of the Fusarium toxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-Ac-DON), 15-acetyldeoxynivalenol (15-Ac-DON), and nivalenol (NIV), in acetonitrile. The calibrators, available in ampoules, were sufficiently homogeneous, with between-bottle variations (s (bb)) of less than 2%. Long-term stability studies performed at four different temperatures between -18 and 40 degrees C revealed no significant negative trends (at a confidence level of 95%). Molar absorptivity coefficients (in L mol(-1) cm(-1)) were determined for all four toxins (DON: 6805 +/- 126, NIV: 6955 +/- 205, 3-Ac-DON: 6983 +/- 141, 15-Ac-DON: 6935 +/- 142) on the basis of a mini-interlaboratory exercise. The overall uncertainty of the calibrators' target values for DON and NIV were evaluated on the basis of gravimetric preparation data and include uncertainty contributions from possible heterogeneity, storage, and transport. The Doncalibrant project resulted in the production of calibrators for DON (IRMM-315) and NIV (IRMM-316) in acetonitrile with certified mass fractions of 25.1 +/- 1.2 microg g(-1) and 24.0 +/- 1.1 microg g(-1), respectively. Both CRMs became commercially available from the Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) at the beginning of 2007.

  1. Influence of the light propagation models on a linearized photoacoustic image reconstruction of the light absorption coefficient

    NASA Astrophysics Data System (ADS)

    Okawa, Shinpei; Hirasawa, Takeshi; Kushibiki, Toshihiro; Ishihara, Miya

    2015-03-01

    Quantification of the optical properties of the tissues and blood by noninvasive photoacoustic (PA) imaging may provide useful information for screening and early diagnosis of diseases. Linearized 2D image reconstruction algorithm based on PA wave equation and the photon diffusion equation (PDE) can reconstruct the image with computational cost smaller than a method based on 3D radiative transfer equation. However, the reconstructed image is affected by the differences between the actual and assumed light propagations. A quantitative capability of a linearized 2D image reconstruction was investigated and discussed by the numerical simulations and the phantom experiment in this study. The numerical simulations with the 3D Monte Carlo (MC) simulation and the 2D finite element calculation of the PDE were carried out. The phantom experiment was also conducted. In the phantom experiment, the PA pressures were acquired by a probe which had an optical fiber for illumination and the ring shaped P(VDF-TrFE) ultrasound transducer. The measured object was made of Intralipid and Indocyanine green. In the numerical simulations, it was shown that the linearized image reconstruction method recovered the absorption coefficients with alleviating the dependency of the PA amplitude on the depth of the photon absorber. The linearized image reconstruction method worked effectively under the light propagation calculated by 3D MC simulation, although some errors occurred. The phantom experiments validated the result of the numerical simulations.

  2. Absolute absorption coefficient of C6H2 in the mid-UV range at low temperature; implications for the interpretation of Titan atmospheric spectra.

    PubMed

    Bénilan, Y; Bruston, P; Raulin, F; Courtin, R; Guillemin, J C

    1995-01-01

    The interpretation of mid-UV albedo spectra of planetary atmospheres, especially that of Titan, is the main goal of the SIPAT (Spectroscopie uv d'Interet Prebiologique dans l'Atmosphere de Titan) research program. This laboratory experiment has been developed in order to systematically determine the absorption coefficients of molecular compounds which are potential absorbers of scattered sunlight in planetary atmospheres, with high spectral resolution, and at various temperatures below room temperature. From photochemical modelling and experimental simulations, we may expect triacetylene (C6H2) to be present in the atmosphere of Titan, even though it has not yet been detected. We present here the first determination of the absolute absorption coefficient of that compound in the 200-300 nm range and at two temperatures (296 K and 233 K). The temperature dependence of the C6H2 absorption coefficient in that wavelength range is compared to that previously observed in the case of cyanoacetylene (HC3N). We then discuss the implications of the present results for the interpretation of Titan UV spectra, where it appears that large uncertainities can be introduced either by the presence of trace impurities in laboratory samples or by the variations of absorption coefficients with temperature.

  3. Spatial variations in the chlorophyll-specific absorption coefficients of phytoplankton and photosynthetically active pigments in the equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Allali, Karima; Bricaud, Annick; Claustre, Hervé

    1997-01-01

    Chlorophyll-specific absorption coefficients of particles, a*p(λ), and of phytoplankton, a*ph(λ), were determined using the glass-fiber filter technique along 150°W in the equatorial Pacific (13°S-1°N). A site-specific algorithm for correcting the path length amplification effect was derived from field measurements. Then a decomposition technique using the high-performance liquid chromatography pigment information and taking into account the package effect was used to partition a*ph into the contributions of photosynthetic pigments (a*ps) and nonphotosynthetic pigments (a*nps). Both a*ph and a*nps values were observed to decrease from the oligotrophic waters of the subequatorial area (13°-1°S) to the mesotrophic waters of the equatorial area (1°S-1°N) and from the surface to deep waters. The a*ph variations were primarily, but not exclusively, caused by changes in the concentrations of nonphotosynthetic pigments. The level of pigment packaging was also variable both horizontally and vertically, as a result of changes in populations and photoacclimation. In comparison with a*ph, a*ps exhibited a reduced range of variation with depth and along the latitudinal gradient. The variations in a*ps originating from the package effect were partly compensated by variations in the concentrations of photosynthetic pigments. We extended this analysis to include data collected in other areas with different trophic states. The a*ps values varied over a factor of 4 at 440 nm, instead of 8 for a*ph, for chlorophyll a concentrations covering 2 orders of magnitude (0.02-2 mg m-3). In agreement with a previous study performed off California with a different method [Sosik and Mitchell, 1995], we conclude that a*ps is less dependent on environmental parameters than a*ph. In addition, our results provide evidence that the variability in a*ps cannot be neglected. The use of a*ps instead of a*ph in light-photosynthesis models (in conjunction with a quantum yield for carbon fixation

  4. Water absorption lines, 931-961 nm - Selected intensities, N2-collision-broadening coefficients, self-broadening coefficients, and pressure shifts in air

    NASA Technical Reports Server (NTRS)

    Giver, L. P.; Gentry, B.; Schwemmer, G.; Wilkerson, T. D.

    1982-01-01

    Intensities were measured for 97 lines of H2O vapor between 932 and 961 nm. The lines were selected for their potential usefulness for remote laser measurements of H2O vapor in the earth's atmosphere. The spectra were obtained with several different H2O vapor abundances and N2 broadening gas pressures; the spectral resolution was 0.046/cm FWHM. Measured H2O line intensities range from 7 x 10 to the -25th to 7 x 10 to the -22nd/cm per (molecules/sq cm). H2O self-broadening coefficients were measured for 13 of these strongest lines; the mean value was 0.5/cm per atm. N2-collision-broadening coefficients were measured for 73 lines, and the average was 0.11 cm per atm HWHM. Pressure shifts in air were determined for a sample of six lines between 948 and 950 nm; these lines shift to lower frequency by an amount comparable to 0.1 of the collision-broadened widths measured in air or N2. The measured intensities of many lines of 300-000 band are much larger than expected from prior computations, in some cases by over an order of magnitude. Coriolis interactions with the stronger 201-000 band appear to be the primary cause of the enhancement of these line intensities.

  5. MAC calorimeters and applications

    SciTech Connect

    MAC Collaboration

    1982-03-01

    The MAC detector at PEP features a large solid-angle electromagnetic/hadronic calorimeter system, augmented by magnetic charged-particle tracking, muon analysis and scintillator triggering. Its implementation in the context of electron-positron annihilation physics is described, with emphasis on the utilization of calorimetry.

  6. Recent results from MAC

    SciTech Connect

    MAC Collaboration

    1982-05-01

    Some preliminary results from the MAC detector at PEP are presented. These include measurements of the angular distribution of ..gamma gamma.., ..mu mu.. and tau tau final states, a determination of the tau lifetime, a measurement of R, and a presentation of the inclusive muon p/sub perpendicular/ distribution for hadronic events.

  7. Measurement of the Two-photon Absorption Coefficient of Gallium Phosphide (GaP) Using a Dispersion-minimized Sub-10 Femtosecond Z-scan Measurement System

    DTIC Science & Technology

    2012-09-01

    bandwidth of the pulse. Using the standard laboratory and analysis methods of Sheik- Bahae et al., we obtain a two-photon absorption coefficient, β, of...organic thin-film materials deposited on various substrates. 15 6. References 1. Sheik- Bahae , M.; Said, A. A.; Van Stryland, E. W. High...sensitivity, Single-beam n2 Measurements. Optics Letters 1989, 14 (17). 2. Sheik- Bahae , M.; Said, A. A.; Van Stryland, E. W.; Wei, T-H; Hagan, D. J

  8. Remote Sensing of the Absorption Coefficients and Chlorophyll a Concentration in the U.S. Southern Middle Atlantic Bight from SeaWiFS and MODIS-Aqua

    NASA Technical Reports Server (NTRS)

    Pan, Xiaoju; Mannino, Antonio; Russ, Mary E.; Hooker, Stanford B.

    2008-01-01

    At present, satellite remote sensing of coastal water quality and constituent concentration is subject to large errors as compared to the capability of satellite sensors in oceanic waters. In this study, field measurements collected on a series of cruises within U.S. southern Middle Atlantic Bight (SMAB) were applied to improve retrievals of satellite ocean color products in order to examine the factors that regulate the bio-optical properties within the continental shelf waters of the SMAB. The first objective was to develop improvements in satellite retrievals of absorption coefficients of phytoplankton (a(sub ph)), colored dissolved organic matter (CDOM) (a(sub g)), non-pigmented particles (a(sub d)), and non-pigmented particles plus CDOM (a(sub dg)), and chlorophyll a concentration ([Chl_a]). Several algorithms were compared to derive constituent absorption coefficients from remote sensing reflectance (R(sub rs)) ratios. The validation match-ups showed that the mean absolute percent differences (MAPD) were typically less than 35%, although higher errors were found for a(sub d) retrievals. Seasonal and spatial variability of satellite-derived absorption coefficients and [Chl_a] was apparent and consistent with field data. CDOM is a major contributor to the bio-optical properties of the SMAB, accounting for 35-70% of total light absorption by particles plus CDOM at 443 nm, as compared to 30-45% for phytoplankton and 0-20% for non-pigmented particles. The overestimation of [Chl_a] from the operational satellite algorithms may be attributed to the strong CDOM absorption in this region. River discharge is important in controlling the bio-optical environment, but cannot explain all of the regional and seasonal variability of biogeochemical constituents in the SMAB.

  9. Exponential Sum Absorption Coefficients of Phosphine from 2750 to 3550/cm for Application to Radiative Transfer Analyses on Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Temma, T.; Baines, K. H.; Butler, R. A. H.; Brown, L. R.; Sagui, L.; Kleiner, I.

    2006-01-01

    PH3 exponential sum k coefficients were computed between 2750 and 3550/cm (2.82-3.64 (microns), in view of future application to radiative transfer analyses of Jupiter and Saturn in a phosphine absorption band near 3 microns. The temperature and pressure of this data set cover the ranges from 80 to 350 K and from 10 (exp -3)to 10(exp 1) bars, respectively. Transmission uncertainty incurred by the use of the k coefficients is smaller than a few percent as long as the radiation is confined above an altitude of a few bars in the giant planets. In spectral regions of weak absorption at high pressures close to 10 bars, contributions from far wings of strong absorption lines must be carefully taken into account. Our data set helps map the three-dimensional distribution of PH3 on the giant planets, revealing their global atmospheric dynamics extending down to the deep interior. The complete k coefficient data set of this work is available at the Web site of the NASA Planetary Data System Atmospheres Node.

  10. Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure

    NASA Astrophysics Data System (ADS)

    Fairuz Budiman, Mohd; Hu, Weiguo; Igarashi, Makoto; Tsukamoto, Rikako; Isoda, Taiga; Itoh, Kohei M.; Yamashita, Ichiro; Murayama, Akihiro; Okada, Yoshitaka; Samukawa, Seiji

    2012-02-01

    A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO2 matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.

  11. Influence of size, proportion, and absorption coefficient of spherical scatterers on the degree of light polarization and the grain size of speckle pattern.

    PubMed

    Nader, Christelle Abou; Nassif, Rana; Pellen, Fabrice; Le Jeune, Bernard; Le Brun, Guy; Abboud, Marie

    2015-12-10

    In this paper, we present the evolution of speckle pattern polarimetric parameters in response to controlled changes in scatterer sizes, proportions, and the absorption coefficient in media. The experimental study was performed on mixtures of polystyrene microspheres with dye in order to ensure biological medium-like properties. The speckle grain sizes and degrees of polarization for linear and circular light were monitored. We observed helicity flipping in the degree of circular polarization for small scatterer proportion around 25%. Furthermore, linear depolarization decreased slightly for media containing more small particles. Good agreement was shown with numerical results computed using a Monte Carlo simulation of polarized light taking into account our experimental configuration. Speckle grain size also evolves with the increase of small scatterers as well as the media absorption coefficient. Such variations of properties are encountered during fruit maturation, in tissues in precancerous stages, and any transformation that causes a modification in particle proportions and absorption coefficient in biological media. The computed parameters proved to be sensitive to these changes.

  12. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV.

    PubMed

    Buhr, H; Büermann, L; Gerlach, M; Krumrey, M; Rabus, H

    2012-12-21

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given.

  13. Nonlinear absorption coefficient and optically detected electrophonon resonance in cylindrical GaAs/AlAs quantum wires with different confined phonon models

    NASA Astrophysics Data System (ADS)

    Khoa, Doan Quoc; Phuong, Le Thi Thu; Hoi, Bui Dinh

    2017-03-01

    A quantum kinetic equation for electrons interacting with confined phonons is used to investigate the nonlinear absorption of an intense electromagnetic wave by electrons in cylindrical GaAs/AlAs quantum wires. The analytic expression for absorption coefficient is calculated for three models of confined optical phonons: the dielectric continuum (DC), hydrodynamic continuum (HC), and Huang-Zhu (HZ) models. The absorption coefficient depends on the square of the electromagnetic wave amplitude. The electrophonon resonance and optically detected electrophonon resonance (ODEPR) are observed through the absorption spectrum. The full width at half maximum (the line-width) of the ODEPR peaks is obtained by a computational method. The line-width is found to increase with increasing temperature and decrease with increasing the quantum wire radius. In particular, numerical results show that the DC and HZ models lead to a similar behaviour of electron - confined phonon interaction whereas the HC model results in a quite different one, especially at small quantum wire radius. For large quantum wire radii, above mentioned phonon models have equivalent contributions to the ODEPR line-width.

  14. An Improvement to a Method for Measuring the Absorption Coefficient of Atmospheric Dust and other Strongly Absorbing Powders

    DTIC Science & Technology

    1975-07-01

    coefficient. Diffuse reflectance spectroscopy, and in particular the Kubelka - Munk (K-M) theory, can provide such information. A convenient method for...34Uber Den Streukoeffizienten Der Kubelka - Munk -Theorie," Z. Naturforsch, 19a, 28. 3. J. B. Gillespie, J. D. Lindberg and L. S. Laude, 1975 " Kubelka ... Munk Optical Coefficients for a Barium Sulfate White Reflectance Standard," Appl. Opt. 14, 807. 4. F. Grum and G. W. Lucky, 1968, "Optical Sphere

  15. Monolithic MACS micro resonators

    NASA Astrophysics Data System (ADS)

    Lehmann-Horn, J. A.; Jacquinot, J.-F.; Ginefri, J. C.; Bonhomme, C.; Sakellariou, D.

    2016-10-01

    Magic Angle Coil Spinning (MACS) aids improving the intrinsically low NMR sensitivity of heterogeneous microscopic samples. We report on the design and testing of a new type of monolithic 2D MACS resonators to overcome known limitations of conventional micro coils. The resonators' conductors were printed on dielectric substrate and tuned without utilizing lumped element capacitors. Self-resonance conditions have been computed by a hybrid FEM-MoM technique. Preliminary results reported here indicate robust mechanical stability, reduced eddy currents heating and negligible susceptibility effects. The gain in B1 /√{ P } is in agreement with the NMR sensitivity enhancement according to the principle of reciprocity. A sensitivity enhancement larger than 3 has been achieved in a monolithic micro resonator inside a standard 4 mm rotor at 500 MHz. These 2D resonators could offer higher performance micro-detection and ease of use of heterogeneous microscopic substances such as biomedical samples, microscopic specimens and thin film materials.

  16. Results from MAC

    SciTech Connect

    Chadwick, G.B.

    1983-05-01

    The MAC detector has been exposed at PEP to 40 pb/sup -1/ luminosity of e/sup +/e/sup -/ collisions. The detector is described and recent results of a continuing analysis of hadronic cross section, lepton pair charge asymmetry, Bhabha process, two photon final state and radiative ..mu.. pairs are given. New results on flavor tagging of hadronic events with an inclusive ..mu.., and some searches for new particles are presented.

  17. Calibration-free absolute quantification of optical absorption coefficients using acoustic spectra in 3D photoacoustic microscopy of biological tissue.

    PubMed

    Guo, Zijian; Hu, Song; Wang, Lihong V

    2010-06-15

    Optical absorption is closely associated with many physiological important parameters, such as the concentration and oxygen saturation of hemoglobin, and it can be used to quantify the concentrations of nonfluorescent molecules. We propose a method to use acoustic spectra of photoacoustic signals to quantify the absolute optical absorption. This method is self-calibrating and thus insensitive to variations in the optical fluence. Factors such as system bandwidth and acoustic attenuation can affect the quantification but can be canceled by dividing the acoustic spectra measured at two optical wavelengths. Using optical-resolution photoacoustic microscopy, we quantified the absolute optical absorption of black ink samples with various concentrations. We also quantified both the concentration and oxygen saturation of hemoglobin in a live mouse in absolute units.

  18. CO2 laser photoacoustic measurements of ethanol absorption coefficients within infrared region of 9.2-10.8 μm

    NASA Astrophysics Data System (ADS)

    Ivascu, I. R.; Matei, C. E.; Patachia, M.; Bratu, A. M.; Dumitras, D. C.

    2016-06-01

    Absorption coefficients of the ethanol vapors at atmospheric pressure and room temperature were measured by photoacoustic technique using a cw, line-tunable, frequency-stabilized CO2 laser as radiation source. The spectrum of the employed CO2 laser includes 54 lines with wavelengths in the infrared region of 9.2-10.8 μm and power levels up to 4.7 W. Measurements revealed a predominant absorption for ethanol within 9.4 μm band of the CO2 laser spectrum, where the highest values of the absorption coefficients were recorded: 3.68 cm- 1 atm- 1 at 9R(20) line and 3.65 cm- 1 atm- 1 at 9R(22) line. The estimated detection range covers six orders of magnitude, from a minimum of 30 ppbV to a maximum of 4% concentration of ethanol in nitrogen, which proves the suitability of the photoacoustic technique for accurate measurements of the ethanol concentration in various applications.

  19. CO2 laser photoacoustic measurements of ethanol absorption coefficients within infrared region of 9.2-10.8 μm.

    PubMed

    Ivascu, I R; Matei, C E; Patachia, M; Bratu, A M; Dumitras, D C

    2016-06-15

    Absorption coefficients of the ethanol vapors at atmospheric pressure and room temperature were measured by photoacoustic technique using a cw, line-tunable, frequency-stabilized CO2 laser as radiation source. The spectrum of the employed CO2 laser includes 54 lines with wavelengths in the infrared region of 9.2-10.8μm and power levels up to 4.7W. Measurements revealed a predominant absorption for ethanol within 9.4μm band of the CO2 laser spectrum, where the highest values of the absorption coefficients were recorded: 3.68cm(-1)atm(-1) at 9R(20) line and 3.65cm(-1)atm(-1) at 9R(22) line. The estimated detection range covers six orders of magnitude, from a minimum of 30ppbV to a maximum of 4% concentration of ethanol in nitrogen, which proves the suitability of the photoacoustic technique for accurate measurements of the ethanol concentration in various applications.

  20. Donor impurity-related optical absorption coefficients and refractive index changes in a rectangular GaAs quantum dot in the presence of electric field

    NASA Astrophysics Data System (ADS)

    Sheng, Wang; Yun, Kang; Xianli, Li

    2016-11-01

    Within the quasi-one-dimensional effective potential model and effective mass approximation, we obtain the wavefunctions and energy eigenvalues of the ground (j = 1) and first 2 excited states (j = 2 and 3) of a donor impurity in a rectangular GaAs quantum dot in the presence of electric field. The donor impurity-related linear and nonlinear optical absorption as well as refractive index changes for the transitions j = 1-2 and j = 2-3 are investigated. The results show that the impurity position, incident optical intensity and electric field play important roles in the optical absorption coefficients and refractive index changes. We find that the impurity effect induces the blueshift for j = 1-2 and redshift for j = 3-2 in the absence of the electric field, but it leads to redshift for j = 1-2 and blueshift for j = 3-2 in the existence of the field. Also, the optical coefficient for the higher energy transitions j = 2-3 is insensitive to variation of impurity positions, while that for the low energy transition j = 1-2 depends significantly on the positions of impurity. In addition, the saturation and splitting phenomenon of the optical absorption are observed as the incident optical intensity increases. Project supported by the Science and Technology Project of Education Department of Heilongjiang Province of China (No. 12541070).

  1. A Multi-Band Analytical Algorithm for Deriving Absorption and Backscattering Coefficients from Remote-Sensing Reflectance of Optically Deep Waters

    NASA Technical Reports Server (NTRS)

    Lee, Zhong-Ping; Carder, Kendall L.

    2001-01-01

    A multi-band analytical (MBA) algorithm is developed to retrieve absorption and backscattering coefficients for optically deep waters, which can be applied to data from past and current satellite sensors, as well as data from hyperspectral sensors. This MBA algorithm applies a remote-sensing reflectance model derived from the Radiative Transfer Equation, and values of absorption and backscattering coefficients are analytically calculated from values of remote-sensing reflectance. There are only limited empirical relationships involved in the algorithm, which implies that this MBA algorithm could be applied to a wide dynamic range of waters. Applying the algorithm to a simulated non-"Case 1" data set, which has no relation to the development of the algorithm, the percentage error for the total absorption coefficient at 440 nm a (sub 440) is approximately 12% for a range of 0.012 - 2.1 per meter (approximately 6% for a (sub 440) less than approximately 0.3 per meter), while a traditional band-ratio approach returns a percentage error of approximately 30%. Applying it to a field data set ranging from 0.025 to 2.0 per meter, the result for a (sub 440) is very close to that using a full spectrum optimization technique (9.6% difference). Compared to the optimization approach, the MBA algorithm cuts the computation time dramatically with only a small sacrifice in accuracy, making it suitable for processing large data sets such as satellite images. Significant improvements over empirical algorithms have also been achieved in retrieving the optical properties of optically deep waters.

  2. The impact of absorption coefficient on polarimetric determination of Berry phase based depth resolved characterization of biomedical scattering samples: a polarized Monte Carlo investigation

    SciTech Connect

    Baba, Justin S; Koju, Vijay; John, Dwayne O

    2016-01-01

    The modulation of the state of polarization of photons due to scatter generates associated geometric phase that is being investigated as a means for decreasing the degree of uncertainty in back-projecting the paths traversed by photons detected in backscattered geometry. In our previous work, we established that polarimetrically detected Berry phase correlates with the mean photon penetration depth of the backscattered photons collected for image formation. In this work, we report on the impact of state-of-linear-polarization (SOLP) filtering on both the magnitude and population distributions of image forming detected photons as a function of the absorption coefficient of the scattering sample. The results, based on Berry phase tracking implemented Polarized Monte Carlo Code, indicate that sample absorption plays a significant role in the mean depth attained by the image forming backscattered detected photons.

  3. Pressure-broadening and narrowing coefficients and temperature dependence measurements of CO2 at 2.68 μm by laser diode absorption spectroscopy for atmospheric applications.

    PubMed

    Ghysels, M; Durry, G; Amarouche, N

    2013-04-15

    By using a tunable diode laser absorption spectrometer in conjunction with a cryogenically cooled multipath cell, we have revisited the air-induced pressure-broadening coefficients and the narrowing coefficients related to the Dicke effect, as well as the temperature dependences, for the R(18) and R(20) lines of the (10°1)I←(00°0) vibrational band at 2.68 μm of carbon dioxide. The selected transitions are used to probe in situ CO2 in the troposphere and the lower stratosphere by using balloon-borne laser sensors. The achieved measurements are thoroughly compared to existing former determinations. The impact of processing the in situ atmospheric CO2 spectra with this new set of molecular data is reported.

  4. Determination of true optical absorption and scattering coefficient of wooden cell wall substance by time-of-flight near infrared spectroscopy.

    PubMed

    Kitamura, Ryunosuke; Inagaki, Tetsuya; Tsuchikawa, Satoru

    2016-02-22

    The true absorption coefficient (μa) and reduced scattering coefficient (μ´s) of the cell wall substance in Douglas fir were determined using time-of-flight near infrared spectroscopy. Samples were saturated with hexane, toluene or quinolone to minimize the multiple reflections of light on the boundary between pore-cell wall substance in wood. μ´s exhibited its minimum value when the wood was saturated with toluene because the refractive index of toluene is close to that of the wood cell wall substance. The optical parameters of the wood cell wall substance calculated were μa = 0.030 mm(-1) and μ´s= 18.4 mm(-1). Monte Carlo simulations using these values were in good agreement with the measured time-resolved transmittance profiles.

  5. Parameter identifiability and Extended Multiple Studies Analysis of a compartmental model for human vitamin A kinetics: fixing fractional transfer coefficients for the initial steps in the absorptive process.

    PubMed

    Park, Hyunjin; Green, Michael H

    2014-03-28

    In the existing compartmental models of human vitamin A metabolism, parameters related to the absorption of the isotopic oral dose have not been well identified. We hypothesised that fixing some poorly identified parameters related to vitamin A absorption would improve parameter identifiability and add statistical certainty to such models. In the present study, data for serum vitamin A kinetics in nine subjects given [2H8]retinyl acetate orally and a model with absorption fixed at 75 % were used to test this hypothesis. In addition to absorption efficiency, we fixed two other fractional transfer coefficients: one representing the initial processing of the ingested dose and the other representing the direct secretion of retinol bound to retinol-binding protein (RBP) from enterocytes into the plasma. The Windows version of Simulation, Analysis and Modeling software (WinSAAM) was used to fit serum tracer data v. time for each subject. Then, a population model was generated by WinSAAM's Extended Multiple Studies Analysis. All the parameters had fractional standard deviations < 0·5, and none of the pairs of parameters had a correlation coefficient >0·8 (accepted criteria for well-identified parameters). Similar to the values predicted by the original model, total traced mass for retinol was 1160 (sd 468) μmol, and the time for retinol to appear in the plasma bound to RBP was 31·3 (sd 4·4) h. In conclusion, we suggest that this approach holds promise for advancing compartmental modelling of vitamin A kinetics in humans when the dose must be administered orally.

  6. A wave based method to predict the absorption, reflection and transmission coefficient of two-dimensional rigid frame porous structures with periodic inclusions

    SciTech Connect

    Deckers, Elke; Claeys, Claus; Atak, Onur; Groby, Jean-Philippe; Dazel, Olivier; Desmet, Wim

    2016-05-01

    This paper presents an extension to the Wave Based Method to predict the absorption, reflection and transmission coefficients of a porous material with an embedded periodic set of inclusions. The porous unit cell is described using the Multi-Level methodology and by embedding Bloch–Floquet periodicity conditions in the weighted residual scheme. The dynamic pressure field in the semi-infinite acoustic domains is approximated using a novel wave function set that fulfils the Helmholtz equation, the Bloch–Floquet periodicity conditions and the Sommerfeld radiation condition. The method is meshless and computationally efficient, which makes it well suited for optimisation studies.

  7. A wave based method to predict the absorption, reflection and transmission coefficient of two-dimensional rigid frame porous structures with periodic inclusions

    NASA Astrophysics Data System (ADS)

    Deckers, Elke; Claeys, Claus; Atak, Onur; Groby, Jean-Philippe; Dazel, Olivier; Desmet, Wim

    2016-05-01

    This paper presents an extension to the Wave Based Method to predict the absorption, reflection and transmission coefficients of a porous material with an embedded periodic set of inclusions. The porous unit cell is described using the Multi-Level methodology and by embedding Bloch-Floquet periodicity conditions in the weighted residual scheme. The dynamic pressure field in the semi-infinite acoustic domains is approximated using a novel wave function set that fulfils the Helmholtz equation, the Bloch-Floquet periodicity conditions and the Sommerfeld radiation condition. The method is meshless and computationally efficient, which makes it well suited for optimisation studies.

  8. Donor impurity-related linear and nonlinear intraband optical absorption coefficients in quantum ring: effects of applied electric field and hydrostatic pressure

    PubMed Central

    2012-01-01

    The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

  9. Influence of image charge effect on impurity-related optical absorption coefficients and refractive index changes in a spherical quantum dot

    NASA Astrophysics Data System (ADS)

    Vartanian, A. L.; Asatryan, A. L.; Vardanyan, L. A.

    2017-03-01

    We have investigated the influence of an image charge effect (ICE) on the energies of the ground and first few excited states of a hydrogen-like impurity in a spherical quantum dot (QD) in the presence of an external electric field. The oscillator strengths of transitions from the 1 s -like state to excited states of 2px and 2pz symmetries are calculated as the functions of the strengths of the confinement potential and the electric field. Also, we have studied the effect of image charges on linear and third-order nonlinear optical absorption coefficients and refractive index changes (RICs). The results show that image charges lead to the decrease of energies for all the hydrogen-like states, to the significant enhancement of the oscillator strengths of transitions between the impurity states, and to comparatively large blue shifts in linear, nonlinear, and total absorption coefficients and refractive index changes. Our results indicate that the total optical characteristics can be controlled by the strength of the confinement and the electric field.

  10. Measurement of the x-ray mass energy-absorption coefficient of air using 3 keV to 10 keV synchrotron radiation.

    PubMed

    Büermann, L; Grosswendt, B; Kramer, H-M; Selbach, H-J; Gerlach, M; Hoffmann, M; Krumrey, M

    2006-10-21

    For the first time absolute photon mass energy-absorption coefficients of air in the energy range 3 keV to 10 keV have been measured with relative standard uncertainties less than 1%, significantly smaller than those of up to 5% assumed hitherto for calculated data. Monochromatized synchrotron radiation was used to measure both the total radiant energy by means of silicon photodiodes calibrated against a cryogenic radiometer and the fraction of radiant energy that is deposited in dry air by means of a free air ionization chamber. The measured ionization charge was converted into energy absorbed in air by calculated effective W values of photons as a function of their energy based on new measurements of the W values in dry air for electron kinetic energies between 1 keV and 7 keV, also presented in this work. The measured absorption coefficients were compared with state-of-the art calculations and found to agree within 0.7% with data calculated earlier by Hubbell at energies above 4 keV but were found to differ by values up to 2.1% at 10 keV from more recent calculations of Seltzer.

  11. Optimizing Thermal-Optical Analysis for Atmospheric Black Carbon (BC): Determining the Beer-Lambert Mass Without a Fixed Mass Absorption Coefficient for BC

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Norris, G.

    2007-12-01

    In thermal-optical transmission analysis (TOT), laser light passing through a particle-laden filter is monitored while carbonaceous material is removed in several heating steps and measured by flame ionization detection. In a helium atmosphere, the laser signal is attenuated by the pyrolysis of organic carbon (OC). Later, while carbon is removed in an oxidizing atmosphere, the laser signal returns to its value prior to pyrolysis (split point), whereupon the amount of carbon equivalent to the native BC is measured. Since pyrolyzed OC may actually evolve beyond the split point, the specific absorption cross sections of pyrolyzed OC and native BC must be equivalent. Moreover, OC pyrolysis must be sufficient so that unpyrolyzed OC is not measured as BC beyond the split point. Using response surfaces models of the apparent specific absorption cross sections for pyrolyzed OC and what the instrument measures as native BC, we determined the thermal conditions for establishing the equivalence of the apparent cross sections while insuring sufficient pyrolysis of OC. In this way, we have optimized TOT for BC mass based on the Beer-Lambert Law but without the need for an absolute mass absorption coefficient (or an absolute attenuation coefficient) for BC. Optimal thermal conditions for the equivalence of the cross sections were indicated by the intersection of the response surfaces. Concurrently, optimal conditions for sufficient pyrolysis of OC were indicated by a plateau in the response surface for the BC cross section. Modeling was based on extensive analyses of PM2.5 samples collected from Atlanta, Los Angeles, and Seattle. Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

  12. Correlation between octanol/water and liposome/water distribution coefficients and drug absorption of a set of pharmacologically active compounds.

    PubMed

    Esteves, Freddy; Moutinho, Carla; Matos, Carla

    2013-06-01

    Absorption and consequent therapeutic action are key issues in the development of new drugs by the pharmaceutical industry. In this sense, different models can be used to simulate biological membranes to predict the absorption of a drug. This work compared the octanol/water and the liposome/water models. The parameters used to relate the two models were the distribution coefficients between liposomes and water and octanol and water and the fraction of drug orally absorbed. For this study, 66 drugs were collected from literature sources and divided into four groups according to charge and ionization degree: neutral; positively charged; negatively charged; and partially ionized/zwitterionic. The results show a satisfactory linear correlation between the octanol and liposome systems for the neutral (R²= 0.9324) and partially ionized compounds (R²= 0.9367), contrary to the positive (R²= 0.4684) and negatively charged compounds (R²= 0.1487). In the case of neutral drugs, results were similar in both models because of the high fraction orally absorbed. However, for the charged drugs (positively, negatively, and partially ionized/zwitterionic), the liposomal model has a more-appropriate correlation with absorption than the octanol model. These results show that the neutral compounds only interact with membranes through hydrophobic bonds, whereas charged drugs favor electrostatic interactions established with the liposomes. With this work, we concluded that liposomes may be a more-appropriate biomembrane model than octanol for charged compounds.

  13. Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

    NASA Technical Reports Server (NTRS)

    Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

    2008-01-01

    Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

  14. Determination of the quasi-TE mode (in-plane) graphene linear absorption coefficient via integration with silicon-on-insulator racetrack cavity resonators.

    PubMed

    Crowe, Iain F; Clark, Nicholas; Hussein, Siham; Towlson, Brian; Whittaker, Eric; Milosevic, Milan M; Gardes, Frederic Y; Mashanovich, Goran Z; Halsall, Matthew P; Vijayaraghaven, Aravind

    2014-07-28

    We examine the near-IR light-matter interaction for graphene integrated cavity ring resonators based on silicon-on-insulator (SOI) race-track waveguides. Fitting of the cavity resonances from quasi-TE mode transmission spectra reveal the real part of the effective refractive index for graphene, n(eff) = 2.23 ± 0.02 and linear absorption coefficient, α(gTE) = 0.11 ± 0.01dBμm(-1). The evanescent nature of the guided mode coupling to graphene at resonance depends strongly on the height of the graphene above the cavity, which places limits on the cavity length for optical sensing applications.

  15. Extension of the Inverse Adding-Doubling Method to the Measurement of Wavelength-Dependent Absorption and Scattering Coefficients of Biological Samples

    SciTech Connect

    Baba, Justin S; Allegood, Marcus S

    2008-01-01

    Light interaction with biological tissue can be described using three parameters: the scattering and absorption coefficients (us and ua), as well as the anisotropy (g) which describes the directional dependence of the scattered photons. Accurately determining these optical properties for different tissue types at specific wavelengths, and simultaneously, would be beneficial for a variety of different biomedical applications. The goal of this project was to take a user-defined g-value and determine the remaining two parameters for a specified wavelength range for an integrating sphere with a collimated white light input source system. A fully automated computer program and process was developed to collect data for all wavelengths in a timely and accurate manner. LabVIEW was used to write programs to automate: raw intensity data collection from a spectrometer equipped integrating sphere, conversion of the data into a format for analysis via Scott Prahl's Inverse Adding-Doubling (IAD) C code execution, and computation of the optical properties based on the output from the IAD code. To allow data to be passed efficiently between LabVIEW and C code program modules, the two were combined into a single program (OPT 3.1). OPT 3.1 was tested using tissue mimicking phantoms and determination of the absorption and scattering coefficients showed excellent agreement with theory for wavelengths were the user inputted single g-value was sufficiently precise. Future improvements entail providing for multi-wavelength g-value entry to extend the accuracy of results to encompass the complete system multispectral range. Ultimately, the data collection process and algorithms developed through this effort will be used to study actual biological tissues for the purpose of deriving and refining models for light-tissue interactions.

  16. Enhance the optical absorptivity of nanocrystalline TiO2 film with high molar extinction coefficient ruthenium sensitizers for high performance dye-sensitized solar cells.

    PubMed

    Gao, Feifei; Wang, Yuan; Shi, Dong; Zhang, Jing; Wang, Mingkui; Jing, Xiaoyan; Humphry-Baker, Robin; Wang, Peng; Zakeeruddin, Shaik M; Grätzel, Michael

    2008-08-13

    We report two new heteroleptic polypyridyl ruthenium complexes, coded C101 and C102, with high molar extinction coefficients by extending the pi-conjugation of spectator ligands, with a motivation to enhance the optical absorptivity of mesoporous titania film and charge collection yield in a dye-sensitized solar cell. On the basis of this C101 sensitizer, several DSC benchmarks measured under the air mass 1.5 global sunlight have been reached. Along with an acetonitrile-based electrolyte, the C101 sensitizer has already achieved a strikingly high efficiency of 11.0-11.3%, even under a preliminary testing. More importantly, based on a low volatility 3-methoxypropionitrile electrolyte and a solvent-free ionic liquid electrolyte, cells have corresponding >9.0% and approximately 7.4% efficiencies retained over 95% of their initial performances after 1000 h full sunlight soaking at 60 degrees C. With the aid of electrical impedance measurements, we further disclose that, compared to the cell with an acetonitrile-based electrolyte, a dye-sensitized solar cell with an ionic liquid electrolyte shows a feature of much shorter effective electron diffusion lengths due to the lower electron diffusion coefficients and shorter electron lifetimes in the mesoporous titania film, explaining the photocurrent difference between these two type devices. This highlights the next necessary efforts to further improve the efficiency of cells with ionic liquid electrolytes, facilitating the large-scale production and application of flexible thin film mesoscopic solar cells.

  17. Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance.

    PubMed

    Sato, Chie; Shimada, Miho; Tanikawa, Yukari; Hoshi, Yoko

    2013-09-01

    Expanding our previously proposed "time segment analysis" for a two-layered turbid medium, this study attempted to selectively determine the absorption coefficient (μa) of the bottom layer in a four-layered human head model with time-domain near-infrared measurements. The difference curve in the temporal profiles of the light attenuation between an object and a reference medium, which are obtained from Monte Carlo simulations, is divided into segments along the time axis, and a slope for each segment is calculated to obtain the depth-dependent μa(μaseg). The reduced scattering coefficient (μs') of the reference is determined by curve fitting with the temporal point spread function derived from the analytical solution of the diffusion equation to the time-resolved reflectance of the object. The deviation of μaseg from the actual μa is expressed by a function of the ratio of μaseg in an earlier time segment to that in a later segment for mediums with different optical properties and thicknesses of the upper layers. Using this function, it is possible to determine the μa of the bottom layer in a four-layered epoxy resin-based phantom. These results suggest that the method reported here has potential for determining the μa of the cerebral tissue in humans.

  18. Fiverr MacGyver

    NASA Astrophysics Data System (ADS)

    Hut, Rolf; van de Giesen, Nick; Larson, Martha

    2014-05-01

    Crowdsourcing has become popular over the past years, also for scientific endeavors. There are many Citizen Science projects and crowdfunding platforms, such as Kickstarter, that are make helpful contributions to moving environmental science forward. An interesting underused source of useful crowd-derived contributions to research is the website Fiverr.com. On this platform, thousands of people, acting as small-scale freelance contractors, offer their skills in the form of services. The platform offers a chance for people to take a hobby, skill, or pastime and make it something more by reaching out to a wider audience and by receiving a payment in return for services. As is typical of other crowdsourcing platforms, the tasks are small and usually self contained. As the name Fiverr suggests, offers start at US5 to provide a particular service. Services offered range from graphic design, to messages sung or spoken with various styles or accents, to complete apps for Android or iPhone. Skill providers on the platform can accept a range of variation of definition in the tasks, some can be described in general terms, for others it is more appropriate to provide examples. Fiverr provides a central location for those offering skills and those needing services to find each other, it makes it possible to communicate and exchange files, to make payments, and it provides support for resolving disputes. In all cases, it is important to keep expectations aligned with the nature of the platform: quality can and will vary. Ultimately, the critical contribution of Fiverr is not to replace professional services or otherwise save money, but rather to provide access to a large group of people with specialized skills who are able to make a contribution on short notice. In the context of this session, it can be considered a pool of people with MacGyver skills lying in wait of a MacGyyer task to attack. There are many ways in which Fiverr tasks, which are called 'gigs', can be useful in

  19. Diffusion coefficients significant in modeling the absorption rate of carbon dioxide into aqueous blends of N-methyldiethanolamine and diethanolamine and of hydrogen sulfide into aqueous N-methyldiethanolamine

    SciTech Connect

    Adams, M.E.; Marshall, T.L.; Rowley, R.L.

    1998-07-01

    Absorption rates of gaseous CO{sub 2} into aqueous blends of N-methyldiethanolamine (MDEA) and diethanolamine (DEA) and of gaseous H{sub 2}S into aqueous MDEA were measured in a quiescent, inverted-tube diffusiometer by monitoring the rate of pressure drop. A numerical model for absorption, diffusion, and reaction of CO{sub 2} and H{sub 2}S in blends of MDEA, DEA, and water was developed. The model was used to regress diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} for the case of CO{sub 2} absorption and of bisulfide ion for the case of H{sub 2}S absorption from measured absorption rates. CO{sub 2} absorption rates and diffusion coefficients of bicarbonate, carbamate, and MDEAH{sub 2}CO{sub 3} were obtained at 298.2 K and 318.2 K in aqueous solutions containing 50 mass % total amine at DEA:MDEA mole ratios of 1:20, 1:4, 1L3, and 2:3. H{sub 2}S absorption rates and diffusion coefficients of bisulfide ion were obtained at 298.2 K and 318.2 K in aqueous solutions containing 20, 35, and 50 mass % MDEA.

  20. Aerosol absorption coefficient and Equivalent Black Carbon by parallel operation of AE31 and AE33 aethalometers at the Zeppelin station, Ny Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, Konstantinos; Kalogridis, Athina-Cerise; Vratolis, Sterios; Fiebig, Markus

    2016-04-01

    Light absorbing carbon in atmospheric aerosol plays a critical role in radiative forcing and climate change. Despite the long term measurements across the Arctic, comparing data obtained by a variety of methods across stations requires caution. A method for extracting the aerosol absorption coefficient from data obtained over the decades by filter based instrument is still under development. An IASOA Aerosol working group has been initiated to address this and other cross-site aerosol comparison opportunities. Continuous ambient measurements of EBC/light attenuation by means of a Magee Sci. AE-31 aethalometer operating at the Zeppelinfjellet station (474 m asl; 78°54'N, 11°53'E), Ny Ålesund, Svalbard, have been available since 2001 (Eleftheriadis et al, 2009), while a new aethalometer model (AE33, Drinovec et al, 2014) has been installed to operate in parallel from the same inlet since June 2015. Measurements are recorded by a Labview routine collecting all available parameters reported by the two instrument via RS232 protocol. Data are reported at 1 and 10 minute intervals as averages for EBC (μg m-3) and aerosol absorption coefficients (Mm-1) by means of routine designed to report Near Real Time NRT data at the EBAS WDCA database (ebas.nilu.no) Results for the first 6 month period are reported here in an attempt to evaluate comparative performance of the two instruments in terms of their response with respect to the variable aerosol load of light absorbing carbon during the warm and cold seasons found in the high arctic. The application of available conversion schemes for obtaining the absorption coefficient by the two instruments is found to demonstrate a marked difference in their output. During clean periods of low aerosol load (EBC < 30 ng m-3), the two instruments display a better agreement with regression slope for the 880 nm signal between the two at ~ 0.9 compared to a slope at ~ 0.6 during the period of higher absorbing carbon loads (400< EBC<30 ng m

  1. Atmospheric Chemistry of 1-Methoxy 2-Propyl Acetate: UV Absorption Cross Sections, Rate Coefficients, and Products of Its Reactions with OH Radicals and Cl Atoms.

    PubMed

    Zogka, Antonia G; Mellouki, Abdelwahid; Romanias, Manolis N; Bedjanian, Yuri; Idir, Mahmoud; Grosselin, Benoit; Daële, Véronique

    2016-11-17

    The rate coefficients for the reactions of OH and Cl with 1-methoxy 2-propyl acetate (MPA) in the gas phase were measured using absolute and relative methods. The kinetic study on the OH reaction was conducted in the temperature (263-373) K and pressure (1-760) Torr ranges using the pulsed laser photolysis-laser-induced fluorescence technique, a low pressure fast flow tube reactor-quadrupole mass spectrometer, and an atmospheric simulation chamber/GC-FID. The derived Arrhenius expression is kMPA+OH(T) = (2.01 ± 0.02) × 10(-12) exp[(588 ± 123/T)] cm(3) molecule(-1) s(-1). The absolute and relative rate coefficients for the reaction of Cl with MPA were measured at room temperature in the flow reactor and the atmospheric simulation chamber, which led to k(Cl+MPA) = (1.98 ± 0.31) × 10(-10) cm(3) molecule(-1) s(-1). GC-FID, GC-MS, and FT-IR techniques were used to investigate the reaction mechanism in the presence of NO. The products formed from the reaction of MPA with OH and their yields were methyl formate (80 ± 7.3%), acetic acid (50 ± 4.8%), and acetic anhydride (22 ± 2.4%), while for Cl reaction, the obtained yields were 60 ± 5.4, 41 ± 3.8, and 11 ± 1.2%, respectively, for the same products. The UV absorption cross section spectrum of MPA was determined in the wavelength range 210-370 nm. The study has shown no photolysis of MPA under atmospheric conditions. The obtained results are used to derive the atmospheric implication.

  2. Opto-acoustic measurement of the local light absorption coefficient in turbid media: 1. Monte-Carlo simulation of laser fluence distribution at the beam axis beneath the surface of a turbid medium

    SciTech Connect

    Pelivanov, Ivan M; Barskaya, M I; Podymova, N B; Khokhlova, Tanya D; Karabutov, Aleksander A

    2009-09-30

    A new method for measuring the local light absorption coefficient in turbid media, for example, biological tissues, is proposed. The method is based on the fact that the amplitude of the excited opto-acoustic (OA) signal is proportional to the absorbed laser power density (the product of the light absorption coefficient and the laser fluence) at the medium interface. In the first part of the paper, the influence of the laser beam diameter, the light absorption and reduced scattering coefficients on the maximal amplitude of the laser fluence at the laser beam axis in the near-surface layer of the turbid medium is studied by using the Monte-Carlo simulation. The conditions are predicted under which the amplitude of the OA signal detected in a transparent medium in contact with the scattering medium should remain proportional to the light absorption coefficient of the medium under study, when the scattering coefficient in it changes more than twice. The results of the numerical simulation are used for the theoretical substantiation of the OA method being proposed. (measurement of parametrs of laser radiation)

  3. Experimental determination of the absorption cross-section and molar extinction coefficient of CdSe and CdTe nanowires.

    PubMed

    Protasenko, Vladimir; Bacinello, Daniel; Kuno, Masaru

    2006-12-21

    Absorption cross-sections and corresponding molar extinction coefficients of solution-based CdSe and CdTe nanowires (NWs) are determined. Chemically grown semiconductor NWs are made via a recently developed solution-liquid-solid (SLS) synthesis, employing low melting Au/Bi bimetallic nanoparticle "catalysts" to induce one-dimensional (1D) growth. Resulting wires are highly crystalline and have diameters between 5 and 12 nm as well as lengths exceeding 10 microm. Narrow diameters, below twice the corresponding bulk exciton Bohr radius of each material, place CdSe and CdTe NWs within their respective intermediate to weak confinement regimes. Supporting this are solution linear absorption spectra of NW ensembles showing blue shifts relative to the bulk band gap as well as structure at higher energies. In the case of CdSe, the wires exhibit band edge emission as well as strong absorption/emission polarization anisotropies at the ensemble and single-wire levels. Analogous photocurrent polarization anisotropies have been measured in recently developed CdSe NW photodetectors. To further support fundamental NW optical/electrical studies as well as to promote their use in device applications, experimental absorption cross-sections are determined using correlated transmission electron microscopy, UV/visible extinction spectroscopy, and inductively coupled plasma atomic emission spectroscopy. Measured CdSe NW cross-sections for 1 microm long wires (diameters, 6-42 nm) range from 6.93 x 10(-13) to 3.91 x 10(-11) cm2 at the band edge (692-715 nm, 1.73-1.79 eV) and between 3.38 x 10(-12) and 5.50 x 10(-11) cm2 at 488 nm (2.54 eV). Similar values are obtained for 1 microm long CdTe NWs (diameters, 7.5-11.5 nm) ranging from 4.32 x 10(-13) to 5.10 x 10(-12) cm2 at the band edge (689-752 nm, 1.65-1.80 eV) and between 1.80 x 10(-12) and 1.99 x 10(-11) cm2 at 2.54 eV. These numbers compare well with previous theoretical estimates of CdSe/CdTe NW cross-sections far to the blue of the

  4. Intrinsic absolute bioavailability prediction in rats based on in situ absorption rate constants and/or in vitro partition coefficients: 6-fluoroquinolones.

    PubMed

    Sánchez-Castaño, G; Ruíz-García, A; Bañón, N; Bermejo, M; Merino, V; Freixas, J; Garriguesx, T M; Plá-Delfina, J M

    2000-11-01

    A preliminary study attempting to predict the intrinsic absolute bioavailability of a group of antibacterial 6-fluoroquinolones-including true and imperfect homologues as well as heterologues-was carried out. The intrinsic absolute bioavailability of the test compounds, F, was assessed on permanently cannulated conscious rats by comparing the trapezoidal normalized areas under the plasma concentration-time curves obtained by intravenous and oral routes (n = 8-12). The high-performance liquid chromatography analytical methods used for plasma samples are described. Prediction of the absolute bioavailability of the compounds was based on their intrinsic rat gut in situ absorption rate constant, k(a). The working equation was: where T represents the mean absorbing time. A T value of 0.93 (+/-0.06) h provides the best correlation between predicted and experimentally obtained bioavailabilities (F' and F, respectively) when k(a) values are used (slope a = 1.10; intercept b = -0.05; r = 0.991). The k(a) values can also be expressed in function of the in vitro partition coefficients, P, between n-octanol and a phosphate buffer. In this case, theoretical k(a) values can be determined with the parameters of a standard k(a)/P correlation previously established for a group of model compounds. When P values are taken instead of k(a) values, reliable bioavailability predictions can also be made. These and other relevant features of the method are discussed.

  5. H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2Pi) radical - An experimental dipole moment function and state-to-state Einstein A coefficients

    NASA Technical Reports Server (NTRS)

    Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.; Orlando, John J.; Burkholder, James B.

    1990-01-01

    FTIR emission/absorption spectroscopy is used to measure the relative intensities of 88 pairs of rovibrational transitions of OH(X2Pi) distributed over 16 vibrational bands. The experimental technique used to obtain the Einstein A ratios is discussed. The dipole moment function which follows from the intensity ratios along with Einstein A coefficients calculated from mu(r) is presented.

  6. H + O3 Fourier-transform infrared emission and laser absorption studies of OH(X2Pi) radical - An experimental dipole moment function and state-to-state Einstein A coefficients

    NASA Astrophysics Data System (ADS)

    Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.; Orlando, John J.; Burkholder, James B.

    1990-11-01

    FTIR emission/absorption spectroscopy is used to measure the relative intensities of 88 pairs of rovibrational transitions of OH(X2Pi) distributed over 16 vibrational bands. The experimental technique used to obtain the Einstein A ratios is discussed. The dipole moment function which follows from the intensity ratios along with Einstein A coefficients calculated from mu(r) is presented.

  7. Mac OS X for Astronomy

    NASA Astrophysics Data System (ADS)

    Pierfederici, F.; Pirzkal, N.; Hook, R. N.

    Mac OS X is the new Unix based version of the Macintosh operating system. It combines a high performance DisplayPDF user interface with a standard BSD UNIX subsystem and provides users with simultaneous access to a broad range of applications which were not previously available on a single system such as Microsoft Office and Adobe Photoshop, as well as legacy X11-based scientific tools and packages like IRAF, SuperMongo, MIDAS, etc. The combination of a modern GUI layered on top of a familiar UNIX environment paves the way for new, more flexible and powerful astronomical tools to be developed while assuring compatibility with already existing, older programs. In this paper, we outline the strengths of the Mac OS X platform in a scientific environment, astronomy in particular, and point to the numerous astronomical software packages available for this platform; most notably the Scisoft collection which we have compiled.

  8. Cooperative luminescence and absorption in Ytterbium-doped silica fiber and the fiber nonlinear transmission coefficient at λ = 980 nm with a regard to the Ytterbium ion-pairs' effect: Reply

    NASA Astrophysics Data System (ADS)

    Kir'yanov, Alexander V.; Barmenkov, Yuri O.

    2006-07-01

    We reply to the comment [R. Paschotta and A.C. Tropper, Opt. Express, to be published (2006)] on our recent work reporting a study of the cooperative absorption and emission in heavily-doped Ytterbium silica fibers and mechanisms of the fiber nonlinear transmission coefficient reduction due to the Ytterbium ion-pairs’ effect [A.V. Kir’yanov et al., Opt. Express, 14 (9), 3981 (2006)]. We provide some additional evidences for that our work hypotheses and conclusions.

  9. Investigation of black and brown carbon multiple-wavelength-dependent light absorption from biomass and fossil fuel combustion source emissions

    NASA Astrophysics Data System (ADS)

    Olson, Michael R.; Victoria Garcia, Mercedes; Robinson, Michael A.; Van Rooy, Paul; Dietenberger, Mark A.; Bergin, Michael; Schauer, James Jay

    2015-07-01

    Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 µg m-3 to ~0 µg m-3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370 nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520 nm wavelength. The bulk EC MACEC, λ (average at 520 nm = 9.0 ± 3.7 m2 g-1; with OC fraction <0.85 = ~7.5 m2 g-1) and the BrC OC mass absorption cross sections (MACBrC,OC,λ) were calculated; at 370 nm ultraviolet wavelengths; the MACBrC,OC,λ ranged from 0.8 m2 g-1 to 2.29 m2 g-1 (lowest peat, highest kerosene), while at 520 nm wavelength MACBrC,OC,λ ranged from 0.07 m2 g-1 to 0.37 m2 g-1 (lowest peat, highest kerosene/incense mixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

  10. Infrared absorption by pure CO2 near 3340 cm-1: Measurements and analysis of collisional coefficients and line-mixing effects at subatmospheric pressures

    NASA Astrophysics Data System (ADS)

    Daneshvar, L.; Földes, T.; Buldyreva, J.; Vander Auwera, J.

    2014-12-01

    High resolution Fourier transform spectra of the 21102-00001 band of 12C16O2 near 3340 cm-1 have been recorded and analyzed to extract isolated-line intensities and collisional parameters, and first-order line-mixing coefficients. Voigt, hard-collision Rautian and Sobel'man, and quadratic-speed-dependent Voigt profiles have been used. The line-mixing coefficients measured for the three branches have also been evaluated using an Energy-Corrected Sudden approach employing a symmetric metric in the Liouville space. These coefficients compare very favorably with the experimental results and estimations with an algorithm available in the literature. Results of straightforward ECS-modeling of complete band shapes have been compared to the recorded spectra and future improvements of this model required at subatmospheric pressures have been outlined.

  11. George MacDonald's Estimate of Childhood

    ERIC Educational Resources Information Center

    Pridmore, John

    2007-01-01

    The nineteenth-century fantasy writer George MacDonald believed that "it is better to be a child in a green field than a knight of many orders." In this paper, I shall explore the bearing of this high estimate of childhood on spiritual education. MacDonald explores the spirituality of the child in his essay "A Sketch of Individual Development" and…

  12. MacIntyre, Rival Traditions and Education

    ERIC Educational Resources Information Center

    Stolz, Steven A.

    2016-01-01

    This paper critically discusses MacIntyre's thesis that education is essentially a contested concept. In order to contextualise my discussion, I discuss both whether rival educational traditions of education found in MacIntyre's work--which I refer to as instrumental and non-instrumental justifications of education--can be rationally resolved…

  13. Influence of the nature of the absorption band on the potential performance of high molar extinction coefficient ruthenium(II) polypyridinic complexes as dyes for sensitized solar cells.

    PubMed

    Gajardo, Francisco; Barrera, Mauricio; Vargas, Ricardo; Crivelli, Irma; Loeb, Barbara

    2011-07-04

    When tested in solar cells, ruthenium polypyridinic dyes with extended π systems show an enhanced light-harvesting capacity that is not necessarily reflected by a high (collected electrons)/(absorbed photons) ratio. Provided that metal-to-ligand charge transfer bands, MLCT, are more effective, due to their directionality, than intraligand (IL) π-π* bands for the electron injection process in the solar cell, it seems important to explore and clarify the nature of the absorption bands present in these types of dyes. This article aims to elucidate if all the absorbed photons of these dyes are potentially useful in the generation of electric current. In other words, their potentiality as dyes must also be analyzed from the point of view of their contribution to the generation of excited states potentially useful for direct injection. Focusing on the assignment of the absorption bands and the nature of the emitting state, a systematic study for a series of ruthenium complexes with 4,4'-distyryl-2,2'-dipyridine (LH) and 4,4'-bis[p-(dimethylamino)-α-styryl]-2,2'-bipyridine (LNMe(2)) "chromophoric" ligands was undertaken. The observed experimental results were complemented with TDDFT calculations to elucidate the nature of the absorption bands, and a theoretical model was proposed to predict the available energy that could be injected from a singlet or a triplet excited state. For the series studied, the results indicate that the percentage of MLCT character to the anchored ligand for the lower energy absorption band follows the order [Ru(deebpy)(2)(LNMe(2))](PF(6))(2) > [Ru(deebpy)(2)(LH)](PF(6))(2) > [Ru(deebpy)(LH)(2)](PF(6))(2), where deebpy is 4,4'-bis(ethoxycarbonyl)-2,2'-bipyridine, predicting that, at least from this point of view, their efficiency as dyes should follow the same trend.

  14. Characterization and Conductivity Behavior of Magnetic Activated Carbon (MAC) from FeCl2.4H2O-Containing Carbon

    NASA Astrophysics Data System (ADS)

    Aripin, Department Of Physics, Faculty Of Mathematics; Natural Science, Haluoleo University, Kampus Bumi Tridharma Anduonohu Kendari 93232 Indonesia

    2007-05-01

    Activated carbons (AC) and magnetic-containing activated carbons (MAC) have been synthesized using coconut shells as carbon sources and FeCl2.4H2O as magnetic precursor. The samples were characterized by nitrogen sorption, XRD, and FTIR. The BET surface area and total pore volume of MAC increase as the temperature increased. AC has XRD peaks, which evidences an amorphous carbon framework and MAC shows that this material consists of an organized carbon with the nanocrystalline magnetite embedded in its structure. The FTIR spectrum of MAC shows that carboxyl groups decreased as the temperature increased. Absorption bands of MAC shows the stretching and torsional vibration modes of the magnetite Fe-O bond in tetrahedral and octahedral sites, respectively. The electrical conductivity studies showed that conductivity of MAC is more than the AC due to structural properties of carbons exists on a framework containing metal structures.

  15. Linear and nonlinear optical absorption coefficients and refractive index changes in GaN/Al{sub x}Ga{sub (1−x)}N double quantum wells operating at 1.55 μm

    SciTech Connect

    Dakhlaoui, Hassen

    2015-04-07

    In the present paper, the linear and nonlinear optical absorption coefficients and refractive index changes between the ground and the first excited states in double GaN/Al{sub x}Ga{sub (1−x)}N quantum wells are studied theoretically. The electronic energy levels and their corresponding wave functions are obtained by solving Schrödinger-Poisson equations self-consistently within the effective mass approximation. The obtained results show that the optical absorption coefficients and refractive index changes can be red- and blue-shifted through varying the left quantum well width and the aluminum concentration x{sub b2} of the central barrier, respectively. These structural parameters are found to present optimum values for carrying out the transition of 0.8 eV (1.55 μm). Furthermore, we show that the desired transition can also be achieved by replacing the GaN in the left quantum well with Al{sub y}Ga{sub (1−y)}N and by varying the aluminum concentration y{sub Al}. The obtained results give a new degree of freedom in optoelectronic device applications such as optical fiber telecommunications operating at (1.55 μm)

  16. EXTENSION OF THE INVERSE ADDING-DOUBLING METHOD TO THE MEASUREMENT OF WAVELENGTH-DEPENDENT ABSORPTION AND SCATTERING COEFFICIENTS OF BIOLOGICAL SAMPLES

    SciTech Connect

    Allegood, M.S.; Baba, J.S.

    2008-01-01

    Light interaction with biological tissue can be described using three parameters: the scattering and absorption coeffi cients (μs and μa), as well as the anisotropy (g) which describes the directional dependence of the scattered photons. Accurately determining these optical properties for different tissue types at specifi c wavelengths simultaneously would be benefi cial for a variety of different biomedical applications. The goal of this project was to take a user defi ned g-value and determine the remaining two parameters for a specifi ed wavelength range. A fully automated computer program and process was developed to collect data for all wavelengths in a timely and accurate manner. LabVIEW® was used to write programs to automate raw intensity data collection from a spectrometer equipped integrating sphere, conversion of the data into a format for analysis via Scott Prahl’s Inverse Adding-Doubling (IAD) C code execution, and fi nally computation of the optical properties based on the output from the IAD code. To allow data to be passed effi ciently between LabVIEW® and C code program modules, the two were combined into a single program (OPT 3.1). OPT 3.1 was tested using tissue mimicking phantoms. Determination of the absorption and scattering coeffi cients showed excellent agreement with theory for wavelengths where the user inputted single g-value was suffi ciently precise. Future improvements entail providing for multi-wavelength g-value entry to extend the accuracy of results to encompass the complete multispectral range. Ultimately, the data collection process and algorithms developed through this effort will be used to examine actual biological tissues for the purpose of building and refi ning models for light-tissue interactions.

  17. MACS as a tool for international inspections

    SciTech Connect

    Curtiss, J.A.; Indusi, J.P.

    1995-08-01

    The MACS/ACRS (Managed Access by Controlled Sensing/Access by Controlled Remote Sensing) system is a collection of communication devices, video capability, and distance-measuring equipment which can effectively substitute for the physical presence of a challenge inspector within a facility. The MACS design allows growth of the prototype, developed in response to the Chemical Weapons Convention (CWC), into a versatile device for inspection of sensitive nuclear facilities under other international arrangements, for example the proposed Fissile Material Cutoff Convention. A MACS/ACRS-type system in a standard, international-recognized configuration could resolve sensitive information and safety concerns through providing a means of achieving the goals of an inspection while excluding the inspector. We believe the technology used to develop MACS for the Defense Nuclear Agency, followed by ACRS for the Department of Energy, is universally adaptable for minimally-intrusive managed-access international inspections of sensitive sites.

  18. Cleanup MAC and MBA code ATP

    SciTech Connect

    Russell, V.K.

    1994-10-17

    The K Basins Materials Accounting (MAC) and Material Balance (MBA) database system had some minor code cleanup performed to its code. This ATP describes how the code was to be tested to verify its correctness.

  19. User's manual for MacPASCO

    NASA Technical Reports Server (NTRS)

    Lucas, S. H.; Davis, R. C.

    1992-01-01

    A user's manual is presented for MacPASCO, which is an interactive, graphic, preprocessor for panel design. MacPASCO creates input for PASCO, an existing computer code for structural analysis and sizing of longitudinally stiffened composite panels. MacPASCO provides a graphical user interface which simplifies the specification of panel geometry and reduces user input errors. The user draws the initial structural geometry and reduces user input errors. The user draws the initial structural geometry on the computer screen, then uses a combination of graphic and text inputs to: refine the structural geometry; specify information required for analysis such as panel load and boundary conditions; and define design variables and constraints for minimum mass optimization. Only the use of MacPASCO is described, since the use of PASCO has been documented elsewhere.

  20. AeroMACS system characterization and demonstrations

    NASA Astrophysics Data System (ADS)

    Kerczewski, R. J.; Apaza, R. D.; Dimond, R. P.

    This The Aeronautical Mobile Airport Communications System (AeroMACS) is being developed to provide a new broadband wireless communications capability for safety critical communications in the airport surface domain, providing connectivity to aircraft and other ground vehicles as well as connections between other critical airport fixed assets. AeroMACS development has progressed from requirements definition through technology definition, prototype deployment and testing, and now into national and international standards development. The first prototype AeroMACS system has been deployed at the Cleveland Hopkins International Airport (CLE) and the adjacent NASA Glenn Research Center (GRC). During the past three years, extensive technical testing has taken place to characterize the performance of the AeroMACS prototype and provide technical support for the standards development process. The testing has characterized AeroMACS link and network performance over a variety of conditions for both fixed and mobile data transmission and has included basic system performance testing and fixed and mobile applications testing. This paper provides a summary of the AeroMACS performance testing and the status of standardization activities that the testing supports.

  1. AeroMACS System Characterization and Demonstrations

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Apaza, Rafael D.; Dimond, Robert P.

    2013-01-01

    This The Aeronautical Mobile Airport Communications System (AeroMACS) is being developed to provide a new broadband wireless communications capability for safety critical communications in the airport surface domain, providing connectivity to aircraft and other ground vehicles as well as connections between other critical airport fixed assets. AeroMACS development has progressed from requirements definition through technology definition, prototype deployment and testing, and now into national and international standards development. The first prototype AeroMACS system has been deployed at the Cleveland Hopkins International Airport (CLE) and the adjacent NASA Glenn Research Center (GRC). During the past 3 years, extensive technical testing has taken place to characterize the performance of the AeroMACS prototype and provide technical support for the standards development process. The testing has characterized AeroMACS link and network performance over a variety of conditions for both fixed and mobile data transmission and has included basic system performance testing and fixed and mobile applications testing. This paper provides a summary of the AeroMACS performance testing and the status of standardization activities that the testing supports.

  2. AeroMACS System Characterization and Demonstrations

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Apaza, Rafael D.; Dimond, Robert P.

    2013-01-01

    The Aeronautical Mobile Airport Communications System (AeroMACS) is being developed to provide a new broadband wireless communications capability for safety critical communications in the airport surface domain, providing connectivity to aircraft and other ground vehicles as well as connections between other critical airport fixed assets. AeroMACS development has progressed from requirements definition through technology definition, prototype deployment and testing, and now into national and international standards development. The first prototype AeroMACS system has been deployed at the Cleveland Hopkins International Airport (CLE) and the adjacent NASA Glenn Research Center (GRC). During the past three years, extensive technical testing has taken place to characterize the performance of the AeroMACS prototype and provide technical support for the standards development process. The testing has characterized AeroMACS link and network performance over a variety of conditions for both fixed and mobile data transmission and has included basic system performance testing and fixed and mobile applications testing. This paper provides a summary of the AeroMACS performance testing and the status of standardization activities that the testing supports.

  3. Silicon Nanostructures Produced by Modified MacEtch Method for Antireflective Si Surface.

    PubMed

    Nichkalo, Stepan; Druzhinin, Anatoly; Evtukh, Anatoliy; Bratus', Oleg; Steblova, Olga

    2017-12-01

    This work pertains to the method for modification of silicon (Si) wafer morphology by metal-assisted chemical etching (MacEtch) technique suitable for fabrication of antireflective Si surfaces. For this purpose, we made different Au catalyst patterns on the surface of Si substrate. This modification allowed to obtain the close-packed Au nanodrop (ND) pattern that generates the nanowires (NWs) and the well-separated Au NDs, which induce the nanopore (NP) formation. The antireflective properties of these structures in comparison with NWs produced by the conventional Ag-MacEtch method were analysed. The total surface reflectance of 1~7% for SiNWs and ~17% for SiNPs was observed over the entire Si-absorbing region. Moreover, SiNWs prepared by Au-MacEtch demonstrate better antireflective properties in contrast to those formed by conventional Ag-assisted chemical etching. So, the use of SiNWs produced by the modified Au-MacEtch method as the antireflective material is favored over those prepared by Ag-MacEtch due to their higher light absorption and lower reflectance. The possible reason of these findings is discussed.

  4. Silicon Nanostructures Produced by Modified MacEtch Method for Antireflective Si Surface

    NASA Astrophysics Data System (ADS)

    Nichkalo, Stepan; Druzhinin, Anatoly; Evtukh, Anatoliy; Bratus', Oleg; Steblova, Olga

    2017-02-01

    This work pertains to the method for modification of silicon (Si) wafer morphology by metal-assisted chemical etching (MacEtch) technique suitable for fabrication of antireflective Si surfaces. For this purpose, we made different Au catalyst patterns on the surface of Si substrate. This modification allowed to obtain the close-packed Au nanodrop (ND) pattern that generates the nanowires (NWs) and the well-separated Au NDs, which induce the nanopore (NP) formation. The antireflective properties of these structures in comparison with NWs produced by the conventional Ag-MacEtch method were analysed. The total surface reflectance of 1 7% for SiNWs and 17% for SiNPs was observed over the entire Si-absorbing region. Moreover, SiNWs prepared by Au-MacEtch demonstrate better antireflective properties in contrast to those formed by conventional Ag-assisted chemical etching. So, the use of SiNWs produced by the modified Au-MacEtch method as the antireflective material is favored over those prepared by Ag-MacEtch due to their higher light absorption and lower reflectance. The possible reason of these findings is discussed.

  5. Light absorption properties of brown carbon in the high Himalayas

    NASA Astrophysics Data System (ADS)

    Kirillova, Elena N.; Marinoni, Angela; Bonasoni, Paolo; Vuillermoz, Elisa; Facchini, Maria Cristina; Fuzzi, Sandro; Decesari, Stefano

    2016-08-01

    The light-absorbing properties of water-soluble brown carbon (WS-BrC) and methanol-soluble brown carbon (MeS-BrC) were studied in PM10 aerosols collected at the "Nepal Climate Observatory-Pyramid" (NCO-P) station (5079 m above sea level) during the period 2013-2014. The light absorption coefficients of WS-BrC and MeS-BrC were the highest during the premonsoon season and the lowest during monsoon. MeS-BrC absorbs about 2 times higher at 365 nm and about 3 times more at 550 nm compared to WS-BrC. The mass absorption cross section (MAC) of WS-BrC measured at 365 nm is similar to that observed previously at South Asian low-altitude sites. Fractional solar radiation absorption by BrC compared to BC considering the full solar spectrum showed that WS-BrC absorbs 4 ± 1% and MeS-BrC absorbs 9 ± 2% compared to BC at NCO-P. Such ratios become 8 ± 1% (for WS-BrC respect to BC) and 17 ± 5% (for MeS-BrC respect to BC) when accounting for correction factors proposed by previous studies to convert absorption coefficients in bulk solutions into light absorption by accumulation mode aerosol particles. These results confirm the importance of BrC in contributing to light-absorbing aerosols in this region of the world. However, the BrC absorption at 550 nm appears small compared to that of BC (1-5%, or 3-9% with conversion factors), and it is lower compared to global model estimates constrained by Aerosol Robotic Network observations. Finally, our study provides no clear evidence of a change in the fractional contribution of BrC with respect to BC to light absorption in the middle troposphere respect to the Indo-Gangetic plain boundary layer.

  6. HFGMC Enhancement of MAC/GMC

    NASA Technical Reports Server (NTRS)

    Arnold, Steven M.; Aboudi, Jacob; Pindera, Marek-Jerzy; Bednarcyk, Brett A.

    2006-01-01

    Additional information about a mathematical model denoted the high-fidelity generalized method of cells (HFGMC) and implementation of the HFGMC within version 4.0 of the MAC/GMC software has become available. MAC/GMC (Micromechanics Analysis Code With Generalized Method of Cells) was a topic of several prior NASA Tech Briefs articles, version 4.0 having been described in "Comprehensive Micromechanics-Analysis Code - Version 4.0" (LEW-17495-1), NASA Tech Briefs, Vol. 29, No. 9 (September 2005), page 54. MAC/GMC predicts elastic and inelastic thermomechanical responses of composite materials. MAC/GMC utilizes the generalized method of cells (GMC) - a model of micromechanics that predicts macroscopic responses of a composite material as functions of the properties, sizes, shapes, and responses of its constituents (e.g., matrix and fibers). The accuracy of the GMC is limited by neglect of coupling between normal and shear stresses. The HFGMC was developed by combining elements of the GMC and a related model, denoted the higher-order theory for functionally graded materials (HOTFGM), that can account for this coupling. Hence, the HFGMC enables simulation of stress and strain with greater accuracy. Some alterations of the MAC/GMC data structure were necessitated by the greater computational complexity of the HFGMC.

  7. The emission coefficient of uranium plasmas

    NASA Technical Reports Server (NTRS)

    Schneider, R. T.; Campbell, H. D.; Mack, J. M.

    1973-01-01

    The emission coefficient for uranium plasmas (Temperature: 8000 K) was measured for the wavelength range (200 A - 6000 A). The results are compared to theory and other measurements. The absorption coefficient for the same wavelength interval is also given.

  8. Lifetime tests for MAC vertex chamber

    SciTech Connect

    Nelson, H.N.

    1986-07-01

    A vertex chamber for MAC was proposed to increase precision in the measurement of the B hadron and tau lepton lifetimes. Thin-walled aluminized mylar drift tubes were used for detector elements. A study of radiation hardness was conducted under the conditions of the proposed design using different gases and different operating conditions. (LEW)

  9. Managed Access by Controlled Sensing (MACS)

    SciTech Connect

    Curtiss, J.A.; Indusi, J.P.

    1994-08-01

    During chemical weapons challenge inspections, the CWC treaty allows ``alternate means`` of access to be proposed by the nation challenged. BNL`s Safeguards, Safety and Nonproliferation Division is funded by the Defense Nuclear Agency to develop a system to provide the challenge inspection team with a ``virtual presence`` within the facility while denying personal access. A general purpose configuration of a mobile station manned by site personnel and a base station manned by the challenge inspector, supported by a flexible communication system, will allow facility personnel to tailor the basic model to their site. Design of the MACS system is based on maximum use of commercial equipment that is available on the international market. Design requirements for the MACS system include methods of establishing geographical position, distance measuring equipment for use in verifying dimensions on floor plans, video and two-way audio links between the mobile unit and the base station, and portability and versatility of the equipment. The MACS platform will also support deployment of selected instrumentation which the site may offer to the challenge inspection team. This paper describes the design and construction of the prototype MACS system.

  10. MacIntyre, Managerialism and Universities

    ERIC Educational Resources Information Center

    Stolz, Steven A.

    2017-01-01

    MacIntyre's earlier work and concern with social science enquiry not only exposes its limits, but also provides an insight into how its knowledge claims have been put to ideological use. He maintains that the institutional embodiment of these ideological ideas is the bureaucratic manager who has had a negative role to play in social structures…

  11. Exposure histories of lunar meteorites - ALHA81005, MAC88104, MAC88105, and Y791197

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Arnold, J. R.; Klein, J.; Fink, D.; Middleton, R.; Kubik, P. W.; Sharma, P.; Elmore, D.; Reedy, R. C.

    1991-01-01

    The cosmogenic radionuclides Ca-41, Cl-36, Al-26, and Be-10 in the Allan Hills 81005, MacAlpine Hills 88104, MacAlpine Hills 88105, and Yamato 791197 meteorites were measured by accelerator mass spectrometry. Mn-53 in Allan Hills 81005 and Yamato 791197 was measured by neutron activation. These four lunar meteorites experienced similar histories. They were ejected from near the surface of the moon ranging in depth down to 400 g/sq cm and had very short transition times (less than 0.1 Ma) from the moon to the earth. A comparison of the cosmogenic nuclide concentrations in MacAlpine Hills 88104 and MacAlpine Hills 88105 clearly indicates that they are a pair from the same fall.

  12. Hydroxyl radical reaction rate coefficients as a function of temperature and IR absorption cross sections for CF3CH=CH2 (HFO-1243zf), potential replacement of CF3CH2F (HFC-134a).

    PubMed

    González, Sergio; Jiménez, Elena; Ballesteros, Bernabé; Martínez, Ernesto; Albaladejo, José

    2015-04-01

    CF3CH=CH2 (hydrofluoroolefin, HFO-1243zf) is a potential replacement of high global-warming potential (GWP) hydrofluorocarbon (HFC-134a, CF3CFH2). Both the atmospheric lifetime and the radiative efficiency of HFO-1243zf are parameters needed for estimating the GWP of this species. Therefore, the aim of this work is (i) to estimate the atmospheric lifetime of HFO-1243zf from the reported OH rate coefficients, k OH, determined under tropospheric conditions and (ii) to calculate its radiative efficiency from the reported IR absorption cross sections. The OH rate coefficient at 298 K also allows the estimation of the photochemical ozone creation potential (ε(POCP)). The pulsed laser photolysis coupled to a laser-induced fluorescence technique was used to determine k OH for the reaction of OH radicals with HFO-1243zf as a function of pressure (50-650 Torr of He) and temperature (263-358 K). Gas-phase IR spectra of HFO-1243zf were recorded at room temperature using a Fourier transform IR spectrometer between 500 and 4,000 cm(-1). At all temperatures, k OH did not depend on bath gas concentration (i.e., on the total pressure between 50 and 650 Torr of He). A slight but noticeable T dependence of k OH was observed in the temperature range investigated. The observed behavior is well described by the following Arrhenius expression: k OH(T) = (7.65 ± 0.26) × 10(-13) exp [(165 ± 10) / T] cm(3) molecule(-1) s(-1). Negligible IR absorption of HFO-1243zf was observed at wavenumbers greater than 1,700 cm(-1). Therefore, IR absorption cross sections, [Formula: see text], were determined in the 500-1,700 cm(-1) range. Integrated [Formula: see text] were determined between 650 and 1,800 cm(-1) for comparison purposes. The main diurnal removal pathway for HFO-1243zf is the reaction with OH radicals, which accounts for 64% of the overall loss by homogeneous reactions at 298 K. Globally, the lifetime due to OH reaction (τ OH) was estimated to be 8.7 days under

  13. Absorption Coefficient of Alkali Halides. Part I.

    DTIC Science & Technology

    1979-03-01

    442 LIAY OF ~:S42.~SON T111 ALiSON ,’FlON CU12rCIUNT OF .l~i~ FLUORIVIl: (iviunLvr Iiepcndcncu) (cort .i.j) S’t .~Ue Rne uhr~) ~clo Wvna,br n rt...al. [134j reported their results for the region from 0.170 to 0.197 um and Handi et al. [24] reported results for the range of 35 to 770 pm. Li (331...lection Spectra of Pure and Doped Potassium Iodide at Low Temperatures," Appl. Opt., 7(1), 161-5 (1968). L, __ 243 26. Vergnat, P., Claudel, J., Handi

  14. MACS as a tool for international inspections

    SciTech Connect

    Curtiss, J.A.; Indusi, J.P.

    1995-06-01

    General acceptance of the challenge provision in the Chemical Weapons Convention has the potential for influence in other arms control areas. While most applications of the challenge inspection may be straightforward, there may be instances where access to the site by inspectors may be problematic. The MACS system described in this paper was developed to respond to these situations. Inspection and verification may be difficult when a host is unwilling,for valid reasons, to permit physical access to a site. We proposed a system of remote sensors which may be used to demonstrate compliance with Chemical Weapons Convention (CWC) challenge inspections even ff the inspector is physically excluded from a sensitive site. The system is based upon alternative-means-of-access provisions of the CWC. The Defense Nuclear Agency (DNA) funded design and construction of a system prototype, designated as MACS for Managed Access by Controlled Sensing. Features of the MACS design allow growth of the prototype into a versatile device for international monitoring of production facilities and other sites. MACS consists of instrumentation and communication equipment allowing site personnel to conduct a facility tour and perform acceptable measurements, while physically excluding the inspector from the facility. MACS consists of a base station used by the inspector, and a mobile unit used within the facility and manipulated by the facility staff. The base station and the mobile unit are @ed by a communication system, currently realized as a fiber optic cable. The mobile unit is equipped with television cameras and remote-reading distance-measuring equipment (DME) for use in verifying locations and dimensions. Global Positioning System receivers on the mobile unit provide both precise location and dead reckoning, suitable for tracking the mobile unit`s position while within a building when satellite signals are not available.

  15. Effective absorption cross sections and photolysis rates of anthropogenic and biogenic secondary organic aerosols

    NASA Astrophysics Data System (ADS)

    Romonosky, Dian E.; Ali, Nujhat N.; Saiduddin, Mariyah N.; Wu, Michael; Lee, Hyun Ji (Julie); Aiona, Paige K.; Nizkorodov, Sergey A.

    2016-04-01

    Mass absorption coefficient (MAC) values were measured for secondary organic aerosol (SOA) samples produced by flow tube ozonolysis and smog chamber photooxidation of a wide range of volatile organic compounds (VOC), specifically: α-pinene, β-pinene, β-myrcene, d-limonene, farnesene, guaiacol, imidazole, isoprene, linalool, ocimene, p-xylene, 1-methylpyrrole, and 2-methylpyrrole. Both low-NOx and high-NOx conditions were employed during the chamber photooxidation experiments. MAC values were converted into effective molecular absorption cross sections assuming an average molecular weight of 300 g/mol for SOA compounds. The upper limits for the effective photolysis rates of SOA compounds were calculated by assuming unity photolysis quantum yields and convoluting the absorption cross sections with a time-dependent solar spectral flux. A more realistic estimate for the photolysis rates relying on the quantum yield of acetone was also obtained. The results show that condensed-phase photolysis of SOA compounds can potentially occur with effective lifetimes ranging from minutes to days, suggesting that photolysis is an efficient and largely overlooked mechanism of SOA aging.

  16. Manual Ability Classification System (MACS): reliability between therapists and parents in Brazil

    PubMed Central

    Silva, Daniela B. R.; Funayama, Carolina A. R.; Pfeifer, Luzia I.

    2015-01-01

    BACKGROUND: The Manual Ability Classification System (MACS) has been widely used to describe the manual ability of children with cerebral palsy (CP); however its reliability has not been verified in Brazil. OBJECTIVE: To establish the inter- and intra-rater reliability of the Portuguese-Brazil version of the MACS by comparing the classifications given by therapists and parents of children with CP. METHOD: Data were obtained from 90 children with CP between the ages of 4 and 18 years, who were treated at the neurology and rehabilitation clinics of a Brazilian hospital. Therapists (an occupational therapist and a student) classified manual ability (MACS) through direct observation and information provided by parents. Therapists and parents used the Portuguese-Brazil version of the MACS. Intra- and inter-rater reliability was obtained using unweighted Kappa coefficient (k) and intra-class correlation coefficient (ICC). The Chi-square test was used to identify the predominance of disagreements in the classification of parents and therapists. RESULTS: An almost perfect agreement resulted among therapists [K=0.90 (95% CI 0.83-0.97); ICC=0.97 (95%CI 0.96-0.98)], as well as with intra-rater (therapists), with Kappa ranging between 0.83 and 0.95 and ICC between 0.96 and 0.99 for the evaluator with more and less experience in rehabilitation, respectively. The agreement between therapists and parents was fair [K=0.36 (95% CI 0.22-0.50); ICC=0.79 (95% CI 0.70-0.86)]. CONCLUSIONS: The Portuguese version of the MACS is a reliable instrument to be used jointly by parents and therapists. PMID:25651133

  17. The periplasmic membrane proximal domain of MacA acts as a switch in stimulation of ATP hydrolysis by MacB transporter.

    PubMed

    Modali, Sita D; Zgurskaya, Helen I

    2011-08-01

    Escherichia coli MacAB-TolC is a tripartite macrolide efflux transporter driven by hydrolysis of ATP. In this complex, MacA is the periplasmic membrane fusion protein that stimulates the activity of MacB transporter and establishes the link with the outer membrane channel TolC. The molecular mechanism by which MacA stimulates MacB remains unknown. Here, we report that the periplasmic membrane proximal domain of MacA plays a critical role in functional MacA-MacB interactions and stimulation of MacB ATPase activity. Binding of MacA to MacB stabilizes the ATP-bound conformation of MacB, whereas interactions with both MacB and TolC affect the conformation of MacA. A single G353A substitution in the C-terminus of MacA inactivates MacAB-TolC function by changing the conformation of the membrane proximal domain of MacA and disrupting the proper assembly of the MacA-MacB complex. We propose that MacA acts in transport by promoting MacB transition into the closed ATP-bound conformation and in this respect, is similar to the periplasmic solute-binding proteins.

  18. Millisecond timing on PCs and Macs.

    PubMed

    MacInnes, W J; Taylor, T L

    2001-05-01

    A real-time, object-oriented solution for displaying stimuli on Windows 95/98, MacOS and Linux platforms is presented. The program, written in C++, utilizes a special-purpose window class (GLWindow), OpenGL, and 32-bit graphics acceleration; it avoids display timing uncertainty by substituting the new window class for the default window code for each system. We report the outcome of tests for real-time capability across PC and Mac platforms running a variety of operating systems. The test program, which can be used as a shell for programming real-time experiments and testing specific processors, is available at http://www.cs.dal.ca/~macinnwj. We propose to provide researchers with a sense of the usefulness of our program, highlight the ability of many multitasking environments to achieve real time, as well as caution users about systems that may not achieve real time, even under optimal conditions.

  19. MAC, material accounting database user guide

    SciTech Connect

    Russell, V.K.

    1994-09-22

    The K Basins Material Accounting (MAC) database system user guide describes the user features and functions, and the document is structured like the database menus. This document presents the MAC database system user instructions which explain how to record the movements and configuration of canisters and materials within the K Basins on the computer, the mechanics of handling encapsulation tracking, and administrative functions associated with the system. This document includes the user instructions, which also serve as the software requirements specification for the system implemented on the microcomputer. This includes suggested user keystrokes, examples of screens displayed by the system, and reports generated by the system. It shows how the system is organized, via menus and screens. It does not explain system design nor provide programmer instructions.

  20. The skin notation in the MAC list and classification of dangerous chemicals.

    PubMed

    Kupczewska-Dobecka, Małgorzata; Czerczak, Sławomir

    2006-01-01

    The European Union has published a list of dangerous chemicals, along with classification and labeling; in 1997 the list was adapted to the requirements of Polish regulations and has been continuously updated since then. We have decided to adopt data on dangerous chemicals classification in the list referring to their dermal absorption to assess whether the skin notation is required in the maximum admissible concentration (MAC) list. In Poland, the Group of Experts for Chemical Agents (GECA) decides on assigning the skin absorption notation (symbol Sk) when analyzing the literature data collected in order to prepare occupational exposure limits documentation. The LD50s value serves as the main criterion for assigning the notation. The limit value of 1000 mg/kg has been set as the criterion for applying the skin notation. Documented results of animal and human research, which point to systemic effects resulting from dermal exposure and physicochemical characteristics enabling calculation of the dermal absorption rate may also be used as the basis for assigning the skin notation. Chemicals for which GECA recommended using the skin notation in the 2004 MAC list have been analyzed. It was concluded that information on the classification of chemicals in the list of dangerous chemicals is useful for assessing the skin absorption, but quantitative assessment of absorption rate compared to "safe" levels, using the available theoretical models, should also be attempted.

  1. Deriving brown carbon from multiwavelength absorption measurements: Method and application to AERONET and Aethalometer observations

    SciTech Connect

    Wang, X.; Heald, C. L.; Sedlacek, A.; de Sa, S. S.; Martin, S. T.; Alexander, M. L.; Watson, T. B.; Aiken, A. C.; Springston, S. R.; Artaxo, P.

    2016-10-13

    The radiative impact of organic aerosols (OA) is a large source of uncertainty in estimating the global direct radiative effect (DRE) of aerosols. This radiative impact includes not only light scattering but also light absorption from a subclass of OA referred to as brown carbon (BrC). However the absorption properties of BrC are poorly understood leading to large uncertainties in modelling studies. To obtain observational constraints from measurements, a simple Absorption Ångström Exponent (AAE) method is often used to separate the contribution of BrC absorption from that of black carbon (BC). However, this attribution method is based on assumptions regarding the spectral dependence of BC that are often violated in the ambient atmosphere. Here we develop a new method that decreases the uncertainties associated with estimating BrC absorption. By applying this method to multi-wavelength absorption aerosol optical depth (AAOD) measurements at AERONET sites worldwide and surface aerosol absorption measurements at multiple ambient sites, we estimate that BrC globally contributes 6-40% of the absorption at 440nm. We find that the mass absorption coefficient of OA (OA-MAC) is positively correlated with BC/OA mass ratio. Based on the variability of BC properties and BC/OA emission ratio, we estimate a range of 0.05-1.2 m2/g for OA-MAC at 440nm. Using the combination of AERONET and OMI UV absorption observations we estimate that the AAE388/440nm for BrC is generally ~4 world-wide, with a smaller value in Europe (< 2). Our analyses of two surface sites (Cape Cod, to the southeast of Boston, and the GoAmazon2014/5 T3 site, to the west of Manaus, Brazil) reveal no significant relationship between BrC absorptivity and photochemical aging in typical urban influenced conditions. However, the absorption of BrC measured during the biomass burning season near Manaus is found to decrease with photochemical aging with a lifetime of ~1 day. This lifetime is

  2. Deriving brown carbon from multiwavelength absorption measurements: Method and application to AERONET and Aethalometer observations

    DOE PAGES

    Wang, X.; Heald, C. L.; Sedlacek, A.; ...

    2016-10-13

    The radiative impact of organic aerosols (OA) is a large source of uncertainty in estimating the global direct radiative effect (DRE) of aerosols. This radiative impact includes not only light scattering but also light absorption from a subclass of OA referred to as brown carbon (BrC). However the absorption properties of BrC are poorly understood leading to large uncertainties in modelling studies. To obtain observational constraints from measurements, a simple Absorption Ångström Exponent (AAE) method is often used to separate the contribution of BrC absorption from that of black carbon (BC). However, this attribution method is based on assumptions regardingmore » the spectral dependence of BC that are often violated in the ambient atmosphere. Here we develop a new method that decreases the uncertainties associated with estimating BrC absorption. By applying this method to multi-wavelength absorption aerosol optical depth (AAOD) measurements at AERONET sites worldwide and surface aerosol absorption measurements at multiple ambient sites, we estimate that BrC globally contributes 6-40% of the absorption at 440nm. We find that the mass absorption coefficient of OA (OA-MAC) is positively correlated with BC/OA mass ratio. Based on the variability of BC properties and BC/OA emission ratio, we estimate a range of 0.05-1.2 m2/g for OA-MAC at 440nm. Using the combination of AERONET and OMI UV absorption observations we estimate that the AAE388/440nm for BrC is generally ~4 world-wide, with a smaller value in Europe (< 2). Our analyses of two surface sites (Cape Cod, to the southeast of Boston, and the GoAmazon2014/5 T3 site, to the west of Manaus, Brazil) reveal no significant relationship between BrC absorptivity and photochemical aging in typical urban influenced conditions. However, the absorption of BrC measured during the biomass burning season near Manaus is found to decrease with photochemical aging with a lifetime of ~1 day. This lifetime is comparable to

  3. Visualization of integrin Mac-1 in vivo

    PubMed Central

    Lim, Kihong; Hyun, Young-Min; Lambert-Emo, Kris; Topham, David J; Kim, Minsoo

    2015-01-01

    β2 integrins play critical roles in migration of immune cells and in the interaction with other cells, pathogens, and the extracellular matrix. Among the β2 integrins, Mac-1 (Macrophage antigen-1), composed of CD11b and CD18, is mainly expressed in innate immune cells and plays a major role in cell migration and trafficking. In order to image Mac-1-expressing cells both in live cells and mouse, we generated a knock-in (KI) mouse strain expressing CD11b conjugated with monomeric yellow fluorescent protein (mYFP). Expression of CD11b-mYFP protein was confirmed by Western blot and silver staining of CD11b-immunoprecipitates and total cell lysates from the mouse splenocytes. Mac-1-mediated functions of the KI neutrophils were comparable with those in WT cells. The fluorescence intensity of CD11b-mYFP was sufficient to image CD11b expressing cells in live mice using intravital two-photon microscopy. In vitro, dynamic changes in the intracellular localization of CD11b molecules could be measured by epifluorescent microscopy. Finally, CD11b-expressing immune cells from tissue were easily detected by flow cytometry without anti-CD11b antibody staining. PMID:26342259

  4. Paired lunar meteorites MAC88104 and MAC88105: A new FAN of lunar petrology

    SciTech Connect

    Neal, C.R. Univ. of Notre Dame, IN ); Taylor, L.A. ); Lui, Yungang; Schmitt, R.A. )

    1991-11-01

    New lunar meteorite MAC88104/5 represents an exciting new opportunity to study a potentially unsampled region of the Moon. The authors have analyzed six thin sections by electron microprobe and three bulk samples by Instrumental Neutron Activation (INA) in order to determine the chemical characteristics of this new lunar sample. Lunar meteorite MAC88104/5 is dominated by lithologies of the ferroan anorthosite (FAN) suite and contains abundant granulitized highland clasts, devitrified glass beads of impact origin, and two small clasts which appear to be of basaltic origin. One of these basaltic clasts (clast E in MAC88105,84) is probably mesostasis material, whereas the second larger clast (clast G) may be similar to the Very Low-Ti (VLT) or low-Ti/high-alumina mare basalts. Impact melt clasts MAC88105,69 and ,72 have major and trace element compositions similar to the bulk meteorite. There is little evidence of any LKFM (Low-K Fra Mauro or low-K KREEP) contribution to this meteorite, as MAC88104/5 and other brecciated lunar meteorites are Fe-rich and poor in the incompatible elements relative to Apollo 16 regolith and feldspathic breccias. While the exact site of origin for the lunar meteorites cannot be pinpointed, it is evident that they were divided from a relatively KREEP-free ferroan anorthosite terrain.

  5. Introduction to MacDraft. High-Technology Training Module.

    ERIC Educational Resources Information Center

    Traxler, Gene

    This training module on MacDraft is part of a computer drafting skills unit on communications technology for grades 9-12. The objective is for each student to complete a drawing on the MacIntosh computer using the MacDraft software program. This drawing is to be dimensioned with a dual system and is to include a border and title block. This module…

  6. APC-MAC/TA: Adaptive Power Controlled MAC Protocol with Traffic Awareness for Wireless Sensor Networks

    NASA Astrophysics Data System (ADS)

    Woo, Seok; Kim, Kiseon

    In this paper, we propose an adaptive power controlled MAC protocol with a traffic-aware scheme specifically designed to reduce both energy and latency in wireless sensor networks. Typically, existing MAC protocols for sensor networks sacrifice latency performance for node energy efficiency. However, some sensor applications for emergencies require rather fast transmissions of sensed data, where we need to consider both energy and latency together. The proposed MAC protocol includes two novel ideas: one is a transmission power control scheme for improving latency in high traffic loads, and the other is a traffic-aware scheme to save more energy in low traffic loads. The transmission power control scheme increases channel utilization by mitigating interference between nodes, and the traffic-aware scheme allows nodes to sleep to reduce idle energy consumption when there are no traffic loads in a network. Simulation results show that the proposed protocol significantly reduces the latency as well as the energy consumption compared to the S-MAC protocol specifically for a large transmission power of nodes and low network traffic.

  7. 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…

  8. MacCready awarded Outstanding Student Paper

    NASA Astrophysics Data System (ADS)

    Parker MacCready was selected by the Ocean Sciences Section to receive their Outstanding Student Paper Award from the 1989 Fall Meeting in San Francisco for his paper entitled “Stratified Spin-up Over a Slope.” Following receipt of his Bachelor's degree in architecture from Yale in 1982, MacCready went to China for 5 months to study the language. On his return to Pasadena he worked for 3 years for Aerovironment, Inc., concentrating on building and flying a human-powered aircraft and a giant wing-flapping replica of a pterosaur. Having become interested in the aerodynamics of flappingwing propulsion, he continued his studies at Caltech, where he received his Master's degree in 1986. His informal thesis project was a human-powered hydrofoil boat with flapping-wing propulsion. He is currently working on his doctorate in physical oceanography at the University of Washington, where he is studying the dynamics of stratified, rotating boundary layers over topography. His switch to oceanography was motivated by his feeling that environmental fluid mechanics would become an increasingly relevant subject in light of increasing world pollution. In the future he hopes to go into environmental politics, perhaps in a scientific advisory role.

  9. TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

    USGS Publications Warehouse

    Song, W.-Z.; Huang, R.; Shirazi, B.; LaHusen, R.

    2009-01-01

    Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and each frame into slots. A parent node determines the children's frame assignment based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. First, given any node, at any time slot, there is at most one active sender in its neighborhood (including itself). Second, the packet scheduling with TreeMAC is bufferless, which therefore minimizes the probability of network congestion. Third, the data throughput to the gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24-node testbed show that TreeMAC protocol significantly improves network throughput, fairness, and energy efficiency compared to TinyOS's default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC. Partial results of this paper were published in Song, Huang, Shirazi and Lahusen [W.-Z. Song, R. Huang, B. Shirazi, and R. Lahusen, TreeMAC: Localized TDMA MAC protocol for high-throughput and fairness in sensor networks, in: The 7th Annual IEEE International Conference on Pervasive Computing and Communications, PerCom, March 2009]. Our new contributions include analyses of the performance of TreeMAC from various aspects. We also present more implementation detail and evaluate TreeMAC from other aspects. ?? 2009 Elsevier B.V.

  10. SuperMacLang: Development of an Authoring System.

    ERIC Educational Resources Information Center

    Frommer, Judith; Foelsche, Otmar K. E.

    1999-01-01

    Describes the development of "SuperMacLang, the 1990s version of the MacLang authoring system. An analysis of various features of the program explains the ways in which certain aspects of collaboration and funding affected developer and programming decisions. (Author/VWL)

  11. Steven MacCall: Winner of LJ's 2010 Teaching Award

    ERIC Educational Resources Information Center

    Berry, John N., III

    2010-01-01

    This article profiles Steven L. MacCall, winner of "Library Journal's" 2010 Teaching Award. An associate professor at the School of Library and Information Studies (SLIS) at the University of Alabama, Tuscaloosa, MacCall was nominated by Kathie Popadin, known as "Kpop" to the members of her cohort in the online MLIS program at SLIS. Sixteen of…

  12. MAC of xenon and halothane in rhesus monkeys.

    PubMed

    Whitehurst, S L; Nemoto, E M; Yao, L; Yonas, H

    1994-10-01

    Local cerebral blood flow (LCBF) maps produced by 33% xenon-enhanced computed tomographic scanning (Xe/CT LCBF) are useful in the clinical diagnosis and management of patients with cerebrovascular disorders. However, observations in humans that 25-35% xenon (Xe) inhalation increases cerebral blood flow (CBF) have raised concerns that Xe/CT LCBF measurements may be inaccurate and that Xe inhalation may be hazardous in patients with decreased intracranial compliance. In contrast, 33% Xe does not increase CBF in rhesus monkeys. To determine whether this interspecies difference in the effect of Xe on CBF correlates with an interspecies difference in the anesthetic potency of Xe, we measured the minimum alveolar concentration (MAC) of Xe preventing movement to a tail-clamp stimulus in rhesus monkeys. Using a standard protocol for the determination of MAC in animals, we first measured the MAC of halothane (n = 5), and then used a combination of halothane and Xe to measure the MAC of Xe (n = 7). The halothane MAC was 0.99 +/- 0.12% (M +/- SD), and the Xe MAC was 98 +/- 15%. These results suggest that the MAC of Xe in rhesus monkeys is higher than the reported human Xe MAC value of 71%. Thus the absence of an effect of 33% Xe on CBF in the rhesus monkey may be related to its lower anesthetic potency.

  13. MacBurn's cylinder test problem

    SciTech Connect

    Shestakov, Aleksei I.

    2016-02-29

    This note describes test problem for MacBurn which illustrates its performance. The source is centered inside a cylinder with axial-extent-to-radius ratio s.t. each end receives 1/4 of the thermal energy. The source (fireball) is modeled as either a point or as disk of finite radius, as described by Marrs et al. For the latter, the disk is divided into 13 equal area segments, each approximated as a point source and models a partially occluded fireball. If the source is modeled as a single point, one obtains very nearly the expected deposition, e.g., 1/4 of the flux on each end and energy is conserved. If the source is modeled as a disk, both conservation and energy fraction degrade. However, errors decrease if the source radius to domain size ratio decreases. Modeling the source as a disk increases run-times.

  14. GENETIC FINGERPRINTING OF MYCOBACTERIUM AVIUM COMPLEX (MAC) ORGANISMS ISOLATED FROM HOSPITAL PATIENTS AND THE ENVIRONMENT

    EPA Science Inventory

    A particularly pathogenic group of mycobacteria belong to the Mycobacterium avium complex (MAC), which includes M. avium and M. intracellulare. MAC organisms cause disease in children, the elderly, and immuno-compromised individuals. A critical step in preventing MAC infections...

  15. Paired lunar meteorites MAC88104 and MAC88105 - A new 'FAN' of lunar petrology. [ferroan anorthosite

    NASA Technical Reports Server (NTRS)

    Neal, Clive R.; Taylor, Lawrence A.; Lui, Yun-Gang; Schmitt, Roman A.

    1991-01-01

    To determine the chemical characteristics of the MAC88104/5 meteorite six thin sections and three bulk samples were analyzed by electron microprobe and instrumental neutron activation. It is concluded that this meteorite is dominated by lithologies of the ferroan anorthosite suite and contains abundant granulitized highland clasts, devitrified glass beads of impact origin, and two small clasts of basaltic origin. It is suggested that one of these basaltic clasts, clast E, is mesostasis material, and clast G is similar to the very low-Ti or low-Ti/high-alumina mare basalts. Impact melt clasts MAC88105, 69, and 72 have major and trace element compositions similar to the bulk meteorite.

  16. Middle Atmosphere Cooperation/Summer in Northern Europe (MAC/SINE) and MAC/Epsilon

    NASA Technical Reports Server (NTRS)

    Thrane, E. V.

    1989-01-01

    Two major international campaigns dedicated to the study of middle atmosphere dynamics in high latitudes were successfully completed in 1987. MAC/SINE (Middle Atmosphere Cooperation/Summer in Northern Europe) was carried out during the period 7 June to 19 July, whereas MAC/Epsilon took place in the period 12 October to 15 November. In both campaigns a large number of ground based and rocket techniques were used in a concerted effort to map the dynamical structure of the middle atmosphere over Northern Europe. Although the analysis of the observations has only just started, it is clear that a large and unique data set was obtained, which is believed will provide new insight into the dynamical processes in this interesting region of the atmosphere. A brief overview of the campaigns, their scientific aims, organization and structure is presented.

  17. Magnetically assisted chemical separation (MACS) process: Preparation and optimization of particles for removal of transuranic elements

    SciTech Connect

    Nunez, L.; Kaminski, M.; Bradley, C.; Buchholz, B.A.; Aase, S.B.; Tuazon, H.E.; Vandegrift, G.F.; Landsberger, S.

    1995-05-01

    The Magnetically Assisted Chemical Separation (MACS) process combines the selectivity afforded by solvent extractants with magnetic separation by using specially coated magnetic particles to provide a more efficient chemical separation of transuranic (TRU) elements, other radionuclides, and heavy metals from waste streams. Development of the MACS process uses chemical and physical techniques to elucidate the properties of particle coatings and the extent of radiolytic and chemical damage to the particles, and to optimize the stages of loading, extraction, and particle regeneration. This report describes the development of a separation process for TRU elements from various high-level waste streams. Polymer-coated ferromagnetic particles with an adsorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted with tributyl phosphate (TBP) were evaluated for use in the separation and recovery of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can then be recovered from the solution by using a magnet. The partition coefficients were larger than those expected based on liquid[liquid extractions, and the extraction proceeded with rapid kinetics. Extractants were stripped from the particles with alcohols and 400-fold volume reductions were achieved. Particles were more sensitive to acid hydrolysis than to radiolysis. Overall, the optimization of a suitable NMCS particle for TRU separation was achieved under simulant conditions, and a MACS unit is currently being designed for an in-lab demonstration.

  18. A ferroan region of the lunar highlands as recorded in meteorites MAC88104 and MAC88105

    SciTech Connect

    Jolliff, B.L.; Korotev, R.L.; Haskin, L.A. )

    1991-11-01

    MacAlpine Hills 88104 and 88105 (MAC88104/5) are paired meteorites of noritic anorthosite composition from the lunar highlands. MAC88105 is a breccia composed mainly of melt-breccia clasts in a fine-grained, fragmental, and partly glassy matrix. The most abundant melt lithologies are feldspathic and are similar in composition to the bulk meteorite. Other melt lithologies include feldspathic melt rocks, mafic melt breccias, and a rare melt breccia relatively enriched in incompatible trace elements. Subordinate lithic clasts are granulitic breccias and ferroan (relatively low Mg/(Mg + Fe)) igneous lithologies, including troctolitic anorthosite, anorthositic norite, gabbronorite, and anorthosite. Igneous clasts having mafic mineral compositions more magnesian than Fo{sub 55} and En{sub 60} were not observed. Rare fragments of glass spheres and shards as well as glass clasts indicate that the meteorite was derived from an immature regolith. The bulk composition of MAC88105 is characterized by a molar Mg/(Mg + Fe) ratio of 0.62, at the extreme low end of the range for meteorites from the lunar highlands. Its low concentrations of incompatible trace elements and feldspathic bulk composition (29% Al{sub 2}O{sub 3}), suggests that it, like the other lunar meteorites, formed at a site far removed from the areas sampled by the Apollo missions. Similarities in mineral compositions among the different lithologies of the breccia and the distribution of mineral fragments suggest that most components of the meteorite were derived from a crustal section dominated by material with a noritic anorthosite composition and an affinity of the ferroan suite of plutonic rocks.

  19. TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

    USGS Publications Warehouse

    Song, W.-Z.; Huang, R.; Shirazi, B.; Husent, R.L.

    2009-01-01

    Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and frame into slots. Parent determines children's frame assigmnent based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. Firstly, given any node, at any time slot, there is at most one active sender in its neighborhood (includ ing itself). Secondly, the packet scheduling with TreelMAC is bufferless, which therefore minimizes the probability of network congestion. Thirdly, the data throughput to gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24 node test bed demonstrate that TreeMAC protocol significantly improves network throughput and energy efficiency, by comparing to the TinyOS's default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC[8]. ?? 2009 IEEE.

  20. 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.

  1. Cooperative Energy Harvesting-Adaptive MAC Protocol for WBANs

    PubMed Central

    Esteves, Volker; Antonopoulos, Angelos; Kartsakli, Elli; Puig-Vidal, Manel; Miribel-Català, Pere; Verikoukis, Christos

    2015-01-01

    In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard. PMID:26029950

  2. Cooperative energy harvesting-adaptive MAC protocol for WBANs.

    PubMed

    Esteves, Volker; Antonopoulos, Angelos; Kartsakli, Elli; Puig-Vidal, Manel; Miribel-Català, Pere; Verikoukis, Christos

    2015-05-28

    In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard.

  3. Handling Deafness Problem of Scheduled Multi-Channel Polling MACs

    NASA Astrophysics Data System (ADS)

    Jiang, Fulong; Liu, Hao; Shi, Longxing

    Combining scheduled channel polling with channel diversity is a promising way for a MAC protocol to achieve high energy efficiency and performance under both light and heavy traffic conditions. However, the deafness problem may cancel out the benefit of channel diversity. In this paper, we first investigate the deafness problem of scheduled multi-channel polling MACs with experiments. Then we propose and evaluate two schemes to handle the deafness problem. Our experiment shows that deafness is a significant reason for performance degradation in scheduled multi-channel polling MACs. A proper scheme should be chosen depending on the traffic pattern and the design objective.

  4. Reconstitution of the Escherichia coli macrolide transporter: the periplasmic membrane fusion protein MacA stimulates the ATPase activity of MacB.

    PubMed

    Tikhonova, Elena B; Devroy, Vishakha K; Lau, Sze Yi; Zgurskaya, Helen I

    2007-02-01

    Periplasmic membrane fusion proteins (MFPs) are essential components of the type I protein secretion systems and drug efflux pumps in Gram-negative bacteria. Previous studies suggested that MFPs connect the inner and outer membrane components of the transport systems and by this means co-ordinate the transfer of substrates across the two membranes. In this study, we purified and reconstituted the macrolide transporter MacAB from Escherichia coli. Here, MacA is a periplasmic MFP and MacB is an ABC-type transporter. Similar to other MFP-dependent transporters from E. coli, the in vivo function of MacAB requires the outer membrane channel TolC. The purified MacB displayed a basal ATPase activity in detergent micelles. This activity conformed to Michaelis-Menten kinetics but was unresponsive to substrates or accessory proteins. Upon reconstitution into proteoliposomes, the ATPase activity of MacB was strictly dependent on MacA. The catalytic efficiency of MacAB ATPase was more than 45-fold higher than the activity of MacB alone. Both the N- and C-terminal regions of MacA were essential for this activity. MacA stimulated MacB ATPase only in phospholipid bilayers and did not need the presence of macrolides. Our results suggest that MacA is a functional subunit of the MacB transporter.

  5. PAD-MAC: Primary User Activity-Aware Distributed MAC for Multi-Channel Cognitive Radio Networks

    PubMed Central

    Ali, Amjad; Piran, Md. Jalil; Kim, Hansoo; Yun, Jihyeok; Suh, Doug Young

    2015-01-01

    Cognitive radio (CR) has emerged as a promising technology to solve problems related to spectrum scarcity and provides a ubiquitous wireless access environment. CR-enabled secondary users (SUs) exploit spectrum white spaces opportunistically and immediately vacate the acquired licensed channels as primary users (PUs) arrive. Accessing the licensed channels without the prior knowledge of PU traffic patterns causes severe throughput degradation due to excessive channel switching and PU-to-SU collisions. Therefore, it is significantly important to design a PU activity-aware medium access control (MAC) protocol for cognitive radio networks (CRNs). In this paper, we first propose a licensed channel usage pattern identification scheme, based on a two-state Markov model, and then estimate the future idle slots using previous observations of the channels. Furthermore, based on these past observations, we compute the rank of each available licensed channel that gives SU transmission success assessment during the estimated idle slot. Secondly, we propose a PU activity-aware distributed MAC (PAD-MAC) protocol for heterogeneous multi-channel CRNs that selects the best channel for each SU to enhance its throughput. PAD-MAC controls SU activities by allowing them to exploit the licensed channels only for the duration of estimated idle slots and enables predictive and fast channel switching. To evaluate the performance of the proposed PAD-MAC, we compare it with the distributed QoS-aware MAC (QC-MAC) and listen-before-talk MAC schemes. Extensive numerical results show the significant improvements of the PAD-MAC in terms of the SU throughput, SU channel switching rate and PU-to-SU collision rate. PMID:25831084

  6. Competition at the Wireless Sensor Network MAC Layer: Low Power Probing interfering with X-MAC

    NASA Astrophysics Data System (ADS)

    Zacharias, Sven; Newe, Thomas

    2011-08-01

    Wireless Sensor Networks (WSNs) combine sensors with computer networks and enable very dense, in-situ and live measurements of data over a large area. Since this emerging technology has the potential to be embedded almost everywhere for numberless applications, interference between different networks can become a serious issue. For most WSNs, it is assumed today that the network medium access is non-competitive. On the basis of X-MAC interfered by Low Power Probing, this paper shows the danger and the effects of different sensor networks communicating on a single wireless channel of the 2.4 GHz band, which is used by the IEEE 802.15.4 standard.

  7. MAC mini acceptance test procedure, software Version 3.0

    SciTech Connect

    Russell, V.K.

    1994-10-17

    The K Basins Materials Accounting (MAC) programs had some major improvements made to it to organize the main-tables by Location, Canister, and Material. This ATP describes how the code was to be tested to verify its correctness.

  8. MacSPOC: Orbital trajectory calculations on a laptop computer

    NASA Technical Reports Server (NTRS)

    Adamo, Dan

    1991-01-01

    Orbital trajectory calculations on a laptop computer are presented in the form of the viewgraphs. The following subject areas are covered: laptop computing in the Space Shuttle program; current laptop prototyping with MacSPOC; future laptop applications; and summary.

  9. Aeronautical Mobile Airport Communications System (AeroMACS)

    NASA Technical Reports Server (NTRS)

    Budinger, James M.; Hall, Edward

    2011-01-01

    To help increase the capacity and efficiency of the nation s airports, a secure wideband wireless communications system is proposed for use on the airport surface. This paper provides an overview of the research and development process for the Aeronautical Mobile Airport Communications System (AeroMACS). AeroMACS is based on a specific commercial profile of the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard known as Wireless Worldwide Interoperability for Microwave Access or WiMAX (WiMax Forum). The paper includes background on the need for global interoperability in air/ground data communications, describes potential AeroMACS applications, addresses allocated frequency spectrum constraints, summarizes the international standardization process, and provides findings and recommendations from the world s first AeroMACS prototype implemented in Cleveland, Ohio, USA.

  10. MAC layer security issues in wireless mesh networks

    NASA Astrophysics Data System (ADS)

    Reddy, K. Ganesh; Thilagam, P. Santhi

    2016-03-01

    Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

  11. 5. Photocopy of drawing of Mac Dougall furnace in roaster ...

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

    5. Photocopy of drawing of Mac Dougall furnace in roaster building from John L. Bray, The Principles of Metallurgy Ginn & Co., New York, 1929. - International Smelting & Refining Company, Tooele Smelter, Roaster Building, State Route 178, Tooele, Tooele County, UT

  12. Operational effectiveness of a Multiple Aquila Control System (MACS)

    NASA Technical Reports Server (NTRS)

    Brown, R. W.; Flynn, J. D.; Frey, M. R.

    1983-01-01

    The operational effectiveness of a multiple aquila control system (MACS) was examined under a variety of remotely piloted vehicle (RPV) mission configurations. The set of assumptions and inputs used to form the rules under which a computerized simulation of MACS was run is given. The characteristics that are to govern MACS operations include: the battlefield environment that generates the requests for RPV missions, operating time-lines of the RPV-peculiar equipment, maintenance requirements, and vulnerability to enemy fire. The number of RPV missions and the number of operation days are discussed. Command, control, and communication data rates are estimated by determining how many messages are passed and what information is necessary in them to support ground coordination between MACS sections.

  13. Conformal holonomy in MacDowell-Mansouri gravity

    SciTech Connect

    Reid, James A.; Wang, Charles H.-T.

    2014-03-15

    The MacDowell-Mansouri formulation of general relativity is based on a gauge theory whose gauge algebra depends on the sign of the cosmological constant. In this article, we show that the gauge algebra is uniquely determined by the conformal structure of spacetime itself. Specifically, we show that in vacuum: the spacetime conformal holonomy algebra coincides with the MacDowell-Mansouri gauge algebra for both signs of the cosmological constant, in both Lorentzian and Euclidean metric signatures.

  14. A tribute to Lloyd D. MacLean

    PubMed Central

    Keith, Roger G.

    2015-01-01

    Summary Dr. Lloyd D. MacLean, long-time co-editor of the Canadian Journal of Surgery passed away earlier this year at the age of 90. In order to appreciate the contributions of Dr. MacLean to the journal, this commentary recognizes him as a humble surgeon–scientist who was one of — if not the — most outstanding Canadian ambassadors to academic surgery in North America. PMID:26204372

  15. Results of measurement of radio wave absorption in the ionosphere by the AI method

    NASA Technical Reports Server (NTRS)

    Korinevskaya, N. A.

    1972-01-01

    Median noon absorption values for each month from 1964 through 1967, the diurnal variations of absorption on the regular world days, and the seasonal variations of absorption are given. The dependence of the absorption coefficient on sunspot number is analyzed.

  16. Factor Scores, Structure Coefficients, and Communality Coefficients

    ERIC Educational Resources Information Center

    Goodwyn, Fara

    2012-01-01

    This paper presents heuristic explanations of factor scores, structure coefficients, and communality coefficients. Common misconceptions regarding these topics are clarified. In addition, (a) the regression (b) Bartlett, (c) Anderson-Rubin, and (d) Thompson methods for calculating factor scores are reviewed. Syntax necessary to execute all four…

  17. A Novel Algorithm Applied to Common Thermal-Optical Transmission Data for Determining Mass Absorption Cross Sections of Atmospheric Black Carbon: Applications to the Indian Outflow

    NASA Astrophysics Data System (ADS)

    Andersson, A.; Sheesley, R. J.; Kirillova, E.; Gustafsson, O.

    2010-12-01

    High wintertime concentrations of black carbon aerosols (BCA) over South Asia and the Northern Indian Ocean are thought to have a large impact on the regional climate. Direct absorption of sunlight by BCAs causes heating of the atmosphere and cooling at the surface. To quantify such effects it is important to characterize a number of different properties of the aerosols. Here we present a novel application of the thermal-optical (OCEC) instrument in which the laser beam is used to obtain optical information about the aerosols. In particular, the novel algorithm accounts for non-carbon contributions to the light extinction. Combining these light extinction coefficients with the simultaneously constrained Elemental Carbon (EC) concentrations, the Mass Absorption Cross Section (MAC) is computed. Samples were collected during a continuous 14-month campaign Dec 2008 - Mar 2009 at Sinaghad in Western India and on Hanimaadhoo, the Northernmost Island in the Maldives. This data set suggests that the MAC of the BCAs are variable, sometimes by a factor of 3 compared to the mean. This observation adds to the complexity of calculating the radiative forcing for BCAs, reinforcing previous observations that parameters such as aerosol mixing state and sources need to be taken into account.

  18. Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs

    PubMed Central

    Huang, Jiawei; Li, Qi; Zhong, Shaohua; Liu, Lianhai; Zhong, Ping; Wang, Jianxin; Ye, Jin

    2017-01-01

    Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings. PMID:28208590

  19. Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs.

    PubMed

    Huang, Jiawei; Li, Qi; Zhong, Shaohua; Liu, Lianhai; Zhong, Ping; Wang, Jianxin; Ye, Jin

    2017-02-10

    Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings.

  20. SACRB-MAC: A High-Capacity MAC Protocol for Cognitive Radio Sensor Networks in Smart Grid.

    PubMed

    Yang, Zhutian; Shi, Zhenguo; Jin, Chunlin

    2016-03-31

    The Cognitive Radio Sensor Network (CRSN) is considered as a viable solution to enhance various aspects of the electric power grid and to realize a smart grid. However, several challenges for CRSNs are generated due to the harsh wireless environment in a smart grid. As a result, throughput and reliability become critical issues. On the other hand, the spectrum aggregation technique is expected to play an important role in CRSNs in a smart grid. By using spectrum aggregation, the throughput of CRSNs can be improved efficiently, so as to address the unique challenges of CRSNs in a smart grid. In this regard, we proposed Spectrum Aggregation Cognitive Receiver-Based MAC (SACRB-MAC), which employs the spectrum aggregation technique to improve the throughput performance of CRSNs in a smart grid. Moreover, SACRB-MAC is a receiver-based MAC protocol, which can provide a good reliability performance. Analytical and simulation results demonstrate that SACRB-MAC is a promising solution for CRSNs in a smart grid.

  1. SACRB-MAC: A High-Capacity MAC Protocol for Cognitive Radio Sensor Networks in Smart Grid

    PubMed Central

    Yang, Zhutian; Shi, Zhenguo; Jin, Chunlin

    2016-01-01

    The Cognitive Radio Sensor Network (CRSN) is considered as a viable solution to enhance various aspects of the electric power grid and to realize a smart grid. However, several challenges for CRSNs are generated due to the harsh wireless environment in a smart grid. As a result, throughput and reliability become critical issues. On the other hand, the spectrum aggregation technique is expected to play an important role in CRSNs in a smart grid. By using spectrum aggregation, the throughput of CRSNs can be improved efficiently, so as to address the unique challenges of CRSNs in a smart grid. In this regard, we proposed Spectrum Aggregation Cognitive Receiver-Based MAC (SACRB-MAC), which employs the spectrum aggregation technique to improve the throughput performance of CRSNs in a smart grid. Moreover, SACRB-MAC is a receiver-based MAC protocol, which can provide a good reliability performance. Analytical and simulation results demonstrate that SACRB-MAC is a promising solution for CRSNs in a smart grid. PMID:27043573

  2. Vehicle Health Management Communications Requirements for AeroMACS

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Clements, Donna J.; Apaza, Rafael D.

    2012-01-01

    As the development of standards for the aeronautical mobile airport communications system (AeroMACS) progresses, the process of identifying and quantifying appropriate uses for the system is progressing. In addition to defining important elements of AeroMACS standards, indentifying the systems uses impacts AeroMACS bandwidth requirements. Although an initial 59 MHz spectrum allocation for AeroMACS was established in 2007, the allocation may be inadequate; studies have indicated that 100 MHz or more of spectrum may be required to support airport surface communications. Hence additional spectrum allocations have been proposed. Vehicle health management (VHM) systems, which can produce large volumes of vehicle health data, were not considered in the original bandwidth requirements analyses, and are therefore of interest in supporting proposals for additional AeroMACS spectrum. VHM systems are an emerging development in air vehicle safety, and preliminary estimates of the amount of data that will be produced and transmitted off an aircraft, both in flight and on the ground, have been prepared based on estimates of data produced by on-board vehicle health sensors and initial concepts of data processing approaches. This allowed an initial estimate of VHM data transmission requirements for the airport surface. More recently, vehicle-level systems designed to process and analyze VHM data and draw conclusions on the current state of vehicle health have been undergoing testing and evaluation. These systems make use of vehicle system data that is mostly different from VHM data considered previously for airport surface transmission, and produce processed system outputs that will be also need to be archived, thus generating additional data load for AeroMACS. This paper provides an analysis of airport surface data transmission requirements resulting from the vehicle level reasoning systems, within the context of overall VHM data requirements.

  3. Deriving brown carbon from multiwavelength absorption measurements: method and application to AERONET and Aethalometer observations

    NASA Astrophysics Data System (ADS)

    Wang, Xuan; Heald, Colette L.; Sedlacek, Arthur J.; de Sá, Suzane S.; Martin, Scot T.; Lizabeth Alexander, M.; Watson, Thomas B.; Aiken, Allison C.; Springston, Stephen R.; Artaxo, Paulo

    2016-10-01

    The radiative impact of organic aerosols (OA) is a large source of uncertainty in estimating the global direct radiative effect (DRE) of aerosols. This radiative impact includes not only light scattering but also light absorption from a subclass of OA referred to as brown carbon (BrC). However, the absorption properties of BrC are poorly understood, leading to large uncertainties in modeling studies. To obtain observational constraints from measurements, a simple absorption Ångström exponent (AAE) method is often used to separate the contribution of BrC absorption from that of black carbon (BC). However, this attribution method is based on assumptions regarding the spectral dependence of BC that are often violated in the ambient atmosphere. Here we develop a new AAE method which improves upon previous approaches by using the information from the wavelength-dependent measurements themselves and by allowing for an atmospherically relevant range of BC properties, rather than fixing these at a single assumed value. We note that constraints on BC optical properties and mixing state would help further improve this method. We apply this method to multiwavelength absorption aerosol optical depth (AAOD) measurements at AERONET sites worldwide and surface aerosol absorption measurements at multiple ambient sites. We estimate that BrC globally contributes up to 40 % of the seasonally averaged absorption at 440 nm. We find that the mass absorption coefficient of OA (OA-MAC) is positively correlated with the BC / OA mass ratio. Based on the variability in BC properties and BC / OA emission ratio, we estimate a range of 0.05-1.5 m2 g-1 for OA-MAC at 440 nm. Using the combination of AERONET and OMI UV absorption observations we estimate that the AAE388/440 nm for BrC is generally ˜ 4 worldwide, with a smaller value in Europe (< 2). Our analyses of observations at two surface sites (Cape Cod, to the southeast of Boston, and the GoAmazon2014/5 T3 site, to the west of

  4. A Flexible CSMA based MAC Protocol for Software Defined Radios

    NASA Astrophysics Data System (ADS)

    Puschmann, André; Kalil, Mohamed A.; Mitschele-Thiel, Andreas

    2012-09-01

    In this article, we propose a flexible CSMA based MAC protocol which facilitates research and experimentation using software define radios. The modular architecture allows to employ the protocol on platforms with heterogeneous hardware capabilities and provides the freedom to exchange or adapt the spectrum sensing mechanism without modifying the MAC protocol internals. We discuss the architecture of the protocol and provide structural details of its main components. Furthermore, we present throughput measurements that have been obtained on an example system using host-based spectrum sensing.

  5. Reflective-tube absorption meter

    NASA Astrophysics Data System (ADS)

    Zaneveld, J. Ronald V.; Bartz, Robert; Kitchen, James C.

    1990-09-01

    The design and calibration of a proposed in situ spectral absorption meter is evaluated using a laboratory prototype. The design includes a silver coated (second-surface) glass tube, a tungsten light source (stabilized by means of optical feedback), a monochromator, and a solid state detector. The device measures the absorption coefficient plus a portion of the volume scattering function. Theoretical analyses and laboratory experiments which explore the magnitude and variation of the errors due to scattering and internal reflections are described. Similar analyses are performed on the Cary 1 18 Spectrophotometer to allow cross calibration. Algorithms to yield the abscrption coefficient and the zenith-sun diffuse attenuation coefficient are presented and evaluated. Simultaneous measurement of the beam attenuation or backscattering coefficient allows use of algoriThms with much narrower error bands. The various methods of obtaining absorption and diffuse attenuation values are compared. Procedures for using reverse osmosis filtration to produce a clean water calibration standard are described. An absorption spectrum for pure water is obtained. Development of the absorption meter is proceeding along two lines: 1) a two-wavelength side-by-side LED is being fabricated to allow an in situ chlorophyll a absorption meter to be constructed, and 2) scientific projects using a shipboard or laboratory flow.-through pumping system are being planned.

  6. On the emission coefficient of uranium plasmas.

    NASA Technical Reports Server (NTRS)

    Schneider, R. T.; Campbell, H. D.; Mack, J. M.

    1973-01-01

    The emission coefficient for uranium plasmas (temperature: 8000 K) was measured for the wavelength range from 1200 to 6000 A. The results were compared to theoretical calculations and other measurements. Reasonable agreement between theoretical predictions and our measurements was found in the region from 1200 to 2000 A. Although it was difficult to make absolute comparisons among the different reported measurements, considerable disagreement was found for the higher wavelength region. A short discussion regarding the overall comparisons is given, and final suggestions are made as to the most appropriate emission coefficient values to be used in future design calculations. The absorption coefficient for the same wavelength interval is also reported.

  7. 42 CFR 405.1130 - Effect of the MAC's decision.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Effect of the MAC's decision. 405.1130 Section 405.1130 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICARE PROGRAM FEDERAL HEALTH INSURANCE FOR THE AGED AND DISABLED Determinations, Redeterminations, Reconsiderations, and Appeals Under...

  8. 12 CFR 615.5174 - Farmer Mac securities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... managing credit and interest rate risks, and furthering your mission to finance agriculture. The total... internal controls are in place to prevent loss, in accordance with § 615.5133(e). Management must submit... securities. (2) Credit risk parameters including: (i) The quantities and types of Farmer Mac...

  9. Simulation and Analysis of a Wireless Mac Protocol: MACAW.

    DTIC Science & Technology

    1996-09-01

    MACAW (Medium Access Collision Avoidance Wireless) is a new MAC protocol for wireless LANs proposed by Bharghavan et al. Ref. 2 based on Karn’s MACA...performance of the MACAW protocol occurs at approximately 50% channel load. We have also shown the importance of the backoff algorithm, and finally, we have

  10. MAC/FAC: A Model of Similarity-Based Retrieval.

    ERIC Educational Resources Information Center

    Forbus, Kenneth D.; And Others

    1995-01-01

    Presents MAC/FAC, a model of similarity-based retrieval that attempts to capture psychological phenomena; discusses its limitations and extensions, its relationship with other retrieval models, and its placement in the context of other work on the nature of similarity. Examines the utility of the model through psychological experiments and…

  11. 12 CFR 615.5174 - Farmer Mac securities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) Market risk limits based on the effects that the Farmer Mac securities have on your capital and earnings. (d) Stress Test. You must perform stress tests on mortgage securities that are issued or guaranteed... fails a stress test, you must divest it as required by § 615.5143. Effective Date Note: At 77 FR...

  12. MAC mini acceptance test procedures, software Version 3.3

    SciTech Connect

    Russell, V.K.

    1994-10-17

    The K Basins Materials Accounting (MAC) programs had some improvements made to it to to change slightly the access authorized users had to the modification of critical data. This ATP describes how the code was to be tested to verify its correctness.

  13. God, Sport Philosophy, Kinesiology: A MacIntyrean Examination

    ERIC Educational Resources Information Center

    Twietmeyer, Gregg

    2015-01-01

    Sport philosophy is in crisis. This subdiscipline of kinesiology garners little to no respect and few tenure track lines in kinesiology departments. Why is this the case? Why isn't philosophy held in greater esteem? Is it possible that philosopher Alasdair MacIntyre's (2009) diagnosis found in "God, Philosophy, Universities" could…

  14. The MacArthur Foundation in Nigeria: Report on Activities

    ERIC Educational Resources Information Center

    John D. and Catherine T. MacArthur Foundation, 2009

    2009-01-01

    In 2007, Nigeria passed an important milestone: one elected government passed power to another for the first time in the nation's history. Though imperfect, the poll demonstrated powerfully that Nigeria's representative democracy was not a transient phase between periods of military repression but a growing reality. For 20 years, the MacArthur…

  15. What if MacGyver Taught Physical Education?

    ERIC Educational Resources Information Center

    Marston, Rip; Leech, Trey

    2014-01-01

    In an era of rising childhood obesity rates, many physical educators find themselves with declining financial resources. Similar to how MacGyver had to do when he was in a bind on his self-titled television show, physical educators need to think creatively when providing equipment for use by their students. The problem that has been identified is:…

  16. Modeling Woven Polymer Matrix Composites with MAC/GMC

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M. (Technical Monitor)

    2000-01-01

    NASA's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) is used to predict the elastic properties of plain weave polymer matrix composites (PMCs). The traditional one step three-dimensional homogertization procedure that has been used in conjunction with MAC/GMC for modeling woven composites in the past is inaccurate due to the lack of shear coupling inherent to the model. However, by performing a two step homogenization procedure in which the woven composite repeating unit cell is homogenized independently in the through-thickness direction prior to homogenization in the plane of the weave, MAC/GMC can now accurately model woven PMCs. This two step procedure is outlined and implemented, and predictions are compared with results from the traditional one step approach and other models and experiments from the literature. Full coupling of this two step technique with MAC/ GMC will result in a widely applicable, efficient, and accurate tool for the design and analysis of woven composite materials and structures.

  17. Proposal and Rationale for the Development of a Mac Lab.

    ERIC Educational Resources Information Center

    Bordner, Marsha

    At Clark State Community College (CSCC), in Ohio, faculty in the Commercial Art and English departments have investigated and debated the best uses for a Mac Lab. Computer needs for the Commercial Art Program were determined through visits to local businesses that produce art on a commercial level; to local secondary school commercial art…

  18. Integrated, Kerberized Login on MacOS X

    NASA Technical Reports Server (NTRS)

    Hotz, Henry B.

    2006-01-01

    Context for this information. MacOS X login process and available hooks. Authorization Services configuration. Authorization Services plug-in s. Kerberos plug-in s. Other bugs and recommendations. Authorization Services Called by loginwindow, screen saver and fast user switching. It calls Directory Services, Login Hook, and Login Items (System Preferences).

  19. Generation of MAC waves by convection in Earth's core

    NASA Astrophysics Data System (ADS)

    Jaupart, Etienne; Buffett, Bruce

    2017-03-01

    Convection in Earth's core is a viable mechanism for generating MAC waves when the top of the core is stably stratified. We quantify the generation mechanism by extending the physical description of MAC waves to include a source term due to buoyancy forces in the convecting part of the core. Solutions for the forced motion are obtained using a Green's function, which is constructed from the eigenfunctions for the unforced motion. When the source term is evaluated using the output of a numerical geodynamo model, the largest excitation occurs at even spherical harmonic degrees, corresponding to waves with symmetric azimuthal flow about the equator. We also find that the magnitude of the source term decreases at periods shorter than about 60 years. As a result most of the wave generation is confined to waves with periods of 60 years or longer. Quantitative predictions for the wave amplitudes depend on the projection of the source term into the eigenfunction of the waves. Strong stratification limits the penetration of density anomalies into the stratified layer, which means that the source term is confined to the lowermost part of the layer. Overtones of MAC waves with large amplitudes in the lower part of the stratified layer are more effectively generated by convection, even though these waves are heavily damped by magnetic diffusion. Generation of MAC waves by convection establishes a physical link between observable wave motion and deeper convective processes. Detection of changes in the amplitude and phase of MAC waves would constrain the generation processes and offer insights into the nature of the convection.

  20. Photocopy of drawing (original drawing of MacDill Field in possession ...

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

    Photocopy of drawing (original drawing of MacDill Field in possession of MacDill Air Force Base, Civil Engineering, Tampa, Florida; 1952 architectural drawings by Strategic Air Command, MacDill Air Force Base) BASE LAYOUT, 1952 - MacDill Air Force Base, Bounded by City of Tampa North, Tampa Bay South, Old Tampa Bay West, & Hillsborough Bay East, Tampa, Hillsborough County, FL

  1. Modelling of Medium Access Control (MAC) Protocols for Mobile Ad-Hoc Networks

    DTIC Science & Technology

    2005-06-01

    Slot IP Internet Protocol LAN Local Area Network MAC Medium Access Control MACAW Medium Access Protocol for Wireless LANs MANET Mobile Ad-hoc...Unforced state – It waits after entering the state until it is invoked by another process or an interrupt. It is in dark grey on this report, and red ... green in OPNET. A MAC process model is built for general initialisations of the MAC module, and to invoke the selected MAC protocol process model

  2. Soil moisture retrieval in the Oberpfaffenhofen testsite using MAC Europe AIRSAR data

    NASA Technical Reports Server (NTRS)

    Wever, Tobias; Henkel, Jochen

    1993-01-01

    Soil moisture content is an important parameter in many disciplines of science like hydrology, meteorology, agriculture and others. Microwave remote sensing technique has a high potential in measuring the dielectric constant of soils, which is strongly governed by the soil moisture. Much excellent work has been done on investigating the relationship between backscattering coefficient and soil moisture. Most of these studies are measured in a laboratory or are carried out with a multitemporal data set. This means, that the variation in the backscattering coefficient is only related to the soil moisture because all other parameters influencing the backscattering like surface roughness, vegetation cover, plant geometry, phenology of plants and row direction are kept constant. In this study the sensitivity of the backscattering coefficient to soil moisture of corn fields is investigated. In the framework of the MAC-Europe Campaign in June 1991, the NASA/JPL three-frequency polarimetric AIRSAR system collected data over the test site Oberpfaffenhofen. The AIRSAR campaign in Oberpfaffenhofen was complemented with intensive ground truth measurements. The sampled corn fields are nearly in the range of the same incidence angle (approximately 20 deg) and belong to different soil types. The evaluation was carried out at a single data set. The results show that the backscattering, measured at P-band, can be described with only two parameters very well. The main parameter influencing the backscattering is the soil moisture content; the second subordinated parameter is the row direction.

  3. CoR-MAC: Contention over Reservation MAC Protocol for Time-Critical Services in Wireless Body Area Sensor Networks.

    PubMed

    Yu, Jeongseok; Park, Laihyuk; Park, Junho; Cho, Sungrae; Keum, Changsup

    2016-05-09

    Reserving time slots for urgent data, such as life-critical information, seems to be very attractive to guarantee their deadline requirements in wireless body area sensor networks (WBASNs). On the other hand, this reservation imposes a negative impact on performance for the utilization of a channel. This paper proposes a new channel access scheme referred to as the contention over reservation MAC (CoR-MAC) protocol for time-critical services in wireless body area sensor networks. CoR-MAC uses the dual reservation; if the reserved time slots are known to be vacant, other nodes can access the time slots by contention-based reservation to maximize the utilization of a channel and decrease the delay of the data. To measure the effectiveness of the proposed scheme against IEEE 802.15.4 and IEEE 802.15.6, we evaluated their performances with various performance indexes. The CoR-MAC showed 50% to 850% performance improvement in terms of the delay of urgent and time-critical data according to the number of nodes.

  4. CoR-MAC: Contention over Reservation MAC Protocol for Time-Critical Services in Wireless Body Area Sensor Networks

    PubMed Central

    Yu, Jeongseok; Park, Laihyuk; Park, Junho; Cho, Sungrae; Keum, Changsup

    2016-01-01

    Reserving time slots for urgent data, such as life-critical information, seems to be very attractive to guarantee their deadline requirements in wireless body area sensor networks (WBASNs). On the other hand, this reservation imposes a negative impact on performance for the utilization of a channel. This paper proposes a new channel access scheme referred to as the contention over reservation MAC (CoR-MAC) protocol for time-critical services in wireless body area sensor networks. CoR-MAC uses the dual reservation; if the reserved time slots are known to be vacant, other nodes can access the time slots by contention-based reservation to maximize the utilization of a channel and decrease the delay of the data. To measure the effectiveness of the proposed scheme against IEEE 802.15.4 and IEEE 802.15.6, we evaluated their performances with various performance indexes. The CoR-MAC showed 50% to 850% performance improvement in terms of the delay of urgent and time-critical data according to the number of nodes. PMID:27171085

  5. 33 CFR 165.768 - Security Zone; MacDill Air Force Base, Tampa Bay, FL.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone; MacDill Air Force....768 Security Zone; MacDill Air Force Base, Tampa Bay, FL. (a) Location. The following area is a... title. All waters within Tampa Bay, Florida in the vicinity of MacDill Air Force Base,...

  6. 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.

  7. MacB ABC transporter is a dimer whose ATPase activity and macrolide-binding capacity are regulated by the membrane fusion protein MacA.

    PubMed

    Lin, Hong Ting; Bavro, Vassiliy N; Barrera, Nelson P; Frankish, Helen M; Velamakanni, Saroj; van Veen, Hendrik W; Robinson, Carol V; Borges-Walmsley, M Inês; Walmsley, Adrian R

    2009-01-09

    Gram-negative bacteria utilize specialized machinery to translocate drugs and protein toxins across the inner and outer membranes, consisting of a tripartite complex composed of an inner membrane secondary or primary active transporter (IMP), a periplasmic membrane fusion protein, and an outer membrane channel. We have investigated the assembly and function of the MacAB/TolC system that confers resistance to macrolides in Escherichia coli. The membrane fusion protein MacA not only stabilizes the tripartite assembly by interacting with both the inner membrane protein MacB and the outer membrane protein TolC, but also has a role in regulating the function of MacB, apparently increasing its affinity for both erythromycin and ATP. Analysis of the kinetic behavior of ATP hydrolysis indicated that MacA promotes and stabilizes the ATP-binding form of the MacB transporter. For the first time, we have established unambiguously the dimeric nature of a noncanonic ABC transporter, MacB that has an N-terminal nucleotide binding domain, by means of nondissociating mass spectrometry, analytical ultracentrifugation, and atomic force microscopy. Structural studies of ABC transporters indicate that ATP is bound between a pair of nucleotide binding domains to stabilize a conformation in which the substrate-binding site is outward-facing. Consequently, our data suggest that in the presence of ATP the same conformation of MacB is promoted and stabilized by MacA. Thus, MacA would facilitate the delivery of drugs by MacB to TolC by enhancing the binding of drugs to it and inducing a conformation of MacB that is primed and competent for binding TolC. Our structural studies are an important first step in understanding how the tripartite complex is assembled.

  8. Computed survey spectra of 2-5 micron atmospheric absorption

    NASA Astrophysics Data System (ADS)

    Leslie, D. H.; Lebow, P. S.

    1983-08-01

    Computed high resolution survey spectra of atmospheric absorption coefficient vs wavenumber are presented covering the wavelength region 2-5 micrometers. The 1980 AFGL atmospheric absorption parameter compilation was employed with a mid-latitude, sea-level atmospheric model.

  9. Magnetic activated cell sorting (MACS): utility in assisted reproduction.

    PubMed

    Makker, Kartikeya; Agarwal, Ashok; Sharma, Rakesh K

    2008-07-01

    Assisted reproductive techniques (ART) have now been extensively incorporated in the management of infertile couples. But even after rapid methodological and technological advances the success rates of these procedures have been below expectations. This has led to development of many sperm preparation protocols to obtain an ideal semen sample for artificial reproduction. Sperm apoptosis has been heavily linked to failures in reproductive techniques. One of the earliest changes shown by apoptotic spermatozoa is externalization of phosphatidyl serine. Magnetic activated cell sorting (MACS) is a novel sperm preparation technique that separates apoptotic and non-apoptotic spermatozoa based on the expression of phosphatidylserine. This has led to the incorporation of MACS as a sperm preparation technique. The review highlights the principle and mechanism of this novel technique and enumerates its advantages as a sperm preparation technique. Its utility in ART as an efficient tool for sperm recovery and its application in cryopreservation of semen samples is also explained.

  10. Preliminary results on B-anti B mixing from MAC

    SciTech Connect

    Hurst, R.

    1987-05-01

    An excess of like-charge dimuons has been observed with the MAC detector in multihadron events produced in e e annihilation at s = 29 GeV. If this excess is attributed to B - anti B mixing, the corresponding value of the mixing parameter chi = GAMMA(B X)/GAMMA(B X) is chi = 0.21/sub -0.15//sup +0.25/ and chi > 0.02 at 90% C.L.

  11. Determination of mass attenuation coefficients for threshold contrast evaluation in digital mammography

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Semturs, Friedrich; Menhart, Susanne; Figl, Michael

    2010-04-01

    According to the 'European protocol for the quality control of the physical and technical aspects of mammography screening' (EPQC) image quality digital mammography units has to be evaluated at different breast thicknesses. At the standard thickness of 50 mm polymethyl methacrylate (PMMA) image quality is determined by the analysis of CDMAM contrast detail phantom images where threshold contrasts are calculated for different gold disc diameters. To extend these results to other breast thicknesses contrast-to-noise ratios (CNR) and threshold contrast (TC) visibilities have to be calculated for all required thicknesses. To calculate the latter the mass attenuation coefficient (MAC) of gold has to be known for all possible beam qualities in the tube voltage range between 26 and 32 kV. In this paper we first determined the threshold contrast visibility using the CDMAM phantom with the same beam quality at different current-time products (mAs). We can derive from Rose theory that CNR • CT • α = const, where α is the diameter of the gold cylinder. From this the corresponding attenuation coefficients can be calculated. This procedure was repeated for four different beam qualities (Mo/Mo 27kV, Rh/Rh 29kV, Rh/Rh 31 kV, and W/Rh 29 kV)). Next, we measured the aluminium half value layer (HVL) of all x-ray spectra relevant for mammography. Using a first order Taylor expansion of MAC as a function of HVL, all other desired MAC can be calculated. The MAC as a function of the HVL was derived to MAChvl = -286.97 * hvl+186.03 with R2 = 0.997, where MAChvl indicates the MAC for all specific x-ray spectrum defined by its aluminium half value layer. Based on this function all necessary MACs needed for quality assurance (QA) were calculated. The results were in good agreement with the data found in the protocol.

  12. Modified Biserial Correlation Coefficients.

    ERIC Educational Resources Information Center

    Kraemer, Helena Chmura

    1981-01-01

    Asymptotic distribution theory of Brogden's form of biserial correlation coefficient is derived and large sample estimates of its standard error obtained. Its relative efficiency to the biserial correlation coefficient is examined. Recommendations for choice of estimator of biserial correlation are presented. (Author/JKS)

  13. Micromechanics Analysis Code (MAC). User Guide: Version 2.0

    NASA Technical Reports Server (NTRS)

    Wilt, T. E.; Arnold, S. M.

    1996-01-01

    The ability to accurately predict the thermomechanical deformation response of advanced composite materials continues to play an important role in the development of these strategic materials. Analytical models that predict the effective behavior of composites are used not only by engineers performing structural analysis of large-scale composite components but also by material scientists in developing new material systems. For an analytical model to fulfill these two distinct functions it must be based on a micromechanics approach which utilizes physically based deformation and life constitutive models and allows one to generate the average (macro) response of a composite material given the properties of the individual constituents and their geometric arrangement. Here the user guide for the recently developed, computationally efficient and comprehensive micromechanics analysis code's (MAC) who's predictive capability rests entirely upon the fully analytical generalized method of cells (GMC), micromechanics model is described. MAC is a versatile form of research software that 'drives' the double or triply periodic micromechanics constitutive models based upon GMC. MAC enhances the basic capabilities of GMC by providing a modular framework wherein (1) various thermal, mechanical (stress or strain control) and thermomechanical load histories can be imposed, (2) different integration algorithms may be selected, (3) a variety of constituent constitutive models may be utilized and/or implemented, and (4) a variety of fiber and laminate architectures may be easily accessed through their corresponding representative volume elements.

  14. Micromechanics Analysis Code (MAC) User Guide: Version 1.0

    NASA Technical Reports Server (NTRS)

    Wilt, T. E.; Arnold, S. M.

    1994-01-01

    The ability to accurately predict the thermomechanical deformation response of advanced composite materials continues to play an important role in the development of these strategic materials. Analytical models that predict the effective behavior of composites are used not only by engineers performing structural analysis of large-scale composite components but also by material scientists in developing new material systems. For an analytical model to fulfill these two distinct functions it must be based on a micromechanics approach which utilizes physically based deformation and life constitutive models and allows one to generate the average (macro) response of a composite material given the properties of the individual constituents and their geometric arrangement. Here the user guide for the recently developed, computationally efficient and comprehensive micromechanics analysis code, MAC, who's predictive capability rests entirely upon the fully analytical generalized method of cells, GMC, micromechanics model is described. MAC is a versatile form of research software that 'drives' the double or triple ply periodic micromechanics constitutive models based upon GMC. MAC enhances the basic capabilities of GMC by providing a modular framework wherein (1) various thermal, mechanical (stress or strain control), and thermomechanical load histories can be imposed; (2) different integration algorithms may be selected; (3) a variety of constituent constitutive models may be utilized and/or implemented; and (4) a variety of fiber architectures may be easily accessed through their corresponding representative volume elements.

  15. Near-infrared absorptions of monomethylhydrazine

    NASA Technical Reports Server (NTRS)

    Murray, Mark; Kurtz, Joe

    1993-01-01

    The peak absorption coefficients for two near-infrared absorptions of monomethylhydrazine, CH3-N2H3, (MMH) were measured. Absorption bands located at 1.524 micrometers (6560/cm), 1.557 micrometers (6423/cm), and 1.583 micrometers (6316/cm) are assigned to the Delta upsilon = 2 overtones of the infared N-H stretching fundamentals at 3317, 3245 and 3177/cm. An absorption band located at 1.04 micrometers (9620 +/- 100/cm) is assigned to the Delta upsilon = 3 overtone of one of these fundamentals. The peak absorption coefficients (alpha(sub 10)) at 1.524 micrometers (6560 +/- 20/cm) and 1.04 micrometers (9620 +/- 100/cm) are 31 x 10(exp -3) and 0.97 x 10(exp -3)/(cm atm), respectively. Uncertainties in these coefficients were estimated to be less than +/- 20% due primarily to uncertainties in the partial vapor pressure of MMH.

  16. Sounding of the Plasmasphere by McMAC Magnetometers

    NASA Astrophysics Data System (ADS)

    Chi, P. J.; McMAC Team

    2012-04-01

    Properly positioned ground magnetometers can be used to detect resonance of magnetospheric field lines as a way to make unique observations of the plasma mass density of the magnetosphere. In this paper we describe the field line resonance (FLR) frequencies systematically observed by the Mid-continent MAgnetoseismic Chain (McMAC), which consists of 10 stations in the United States and Mexico along 300° magnetic longitude. With an average separation by 272 km between adjacent stations McMAC is well suited to remotely sensing the plasma density at L-values between 1.6 and 3.3 through the gradient method of FLR measurements. We analyzed a full year of McMAC observations spanning between July 2006 and June 2007, and FLR frequencies were automatically identified in cross-phase and cross-power spectrograms by a computer routine. In all of the FLR observations by pairs of McMAC stations, the occurrence rate of FLR can reach as high as 55% around local noon at L = 2.7. The occurrence rate drops at lower latitudes due to weaker FLR signals. At L = 3.3 the FLR occurrence is clearly reduced in afternoon hours, possibly because of occasional presence of the plasmapause that can obstruct FLR generation and/or detection. By examining the results from all possible pairs of McMAC stations, we find that, at L ≤ 2.5, FLR signatures can still be found even when the separation between two stations exceeds 1000 km. The fundamental mode FLR frequencies, in addition to the inferred equatorial plasma mass densities of the magnetosphere, are tabulated with respect to L-value and time. The most probable fundamental mode frequency is found to be approximately 75 mHz at L = 1.6 and decreases with increasing L-value. The distribution of the fundamental mode frequency at L = 3.3, however, exhibits two distinct groups: The lower frequencies centered at 10 mHz representing the measurements inside the plasmasphere whereas the higher frequencies centered at 39 mHz indicating the faster field

  17. Ultraviolet absorption cross sections of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Lin, C. L.; Rohatgi, N. K.; Demore, W. B.

    1978-01-01

    Absorption cross-sections of hydrogen peroxide vapor and of neutral aqueous solutions of hydrogen peroxide were measured in the wavelength range from 195 to 350 nm at 296 K. The spectrophotometric procedure is described, and the reported cross-sections are compared with values obtained by other researchers. Photodissociation coefficients of atmospheric H2O2 were calculated for direct absorption of unscattered solar radiation, and the vertical distributions of these coefficients are shown for various solar zenith angles.

  18. MacA, a periplasmic membrane fusion protein of the macrolide transporter MacAB-TolC, binds lipopolysaccharide core specifically and with high affinity.

    PubMed

    Lu, Shuo; Zgurskaya, Helen I

    2013-11-01

    The Escherichia coli MacAB-TolC transporter has been implicated in efflux of macrolide antibiotics and secretion of enterotoxin STII. In this study, we found that purified MacA, a periplasmic membrane fusion protein, contains one tightly bound rough core lipopolysaccharide (R-LPS) molecule per MacA molecule. R-LPS was bound specifically to MacA protein with affinity exceeding that of polymyxin B. Sequence analyses showed that MacA contains two high-density clusters of positively charged amino acid residues located in the cytoplasmic N-terminal domain and the periplasmic C-terminal domain. Substitutions in the C-terminal cluster reducing the positive-charge density completely abolished binding of R-LPS. At the same time, these substitutions significantly reduced the functionality of MacA in the protection of E. coli against macrolides in vivo and in the in vitro MacB ATPase stimulation assays. Taken together, our results suggest that R-LPS or a similar glycolipid is a physiological substrate of MacAB-TolC.

  19. Total and Partial Absorption Coefficients for a Nitrogen Plasma

    DTIC Science & Technology

    2014-09-26

    Boulder, CO 80309 ATTN: Dr. Arthur V. Phelps 43 0 - . .. > . v- . - . -, . . " )h A’ I , U’ C ’ -- o. • p Lawrence Berkeley Laboratory University of...Gerald N. Hays Dr. James Chang Dr. Michael G. Mazerakis RiJ University of California Physics Department Irvine, CA 92664 -ATTN: Dr. Gregory Benford Air

  20. Absorption of CO laser radiation by NO

    NASA Technical Reports Server (NTRS)

    Hanson, R. K.; Monat, J. P.; Kruger, C. H.

    1976-01-01

    The paper describes absorption calculations and measurements at selected infrared CO laser wavelengths which are nearly coincident with absorption lines in the fundamental vibration-rotation band of NO near 5.3 microns. Initial work was directed towards establishing the optimal CO laser-NO absorption line coincidence for high temperature applications. Measurements of the absorption coefficient at this optimal laser wavelength were carried out, first using a room-temperature absorption cell for high-temperature calculations and then using a shock tube, for the temperature range 630-4000 K, to validate the high temperature calculations.

  1. Coefficients of Effective Length.

    ERIC Educational Resources Information Center

    Edwards, Roger H.

    1981-01-01

    Under certain conditions, a validity Coefficient of Effective Length (CEL) can produce highly misleading results. A modified coefficent is suggested for use when empirical studies indicate that underlying assumptions have been violated. (Author/BW)

  2. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  3. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  4. Gasoline-Water Distribution Coefficients of Xylidines

    DTIC Science & Technology

    1943-06-01

    sample calculated. The extinction (absorption) of light is related to the concentration of the absorbing group by the Beer - Lambert law. It was neceaaar...the use of a Beckman quartz spectrophotometer . Data obtained 1dth the spectzrograph were checzed with the spectrophotom- eter and were reproducible to...within 5 percent of the value of the distribution coefficient given, The use of the spectrophotometer greatly enhanced the speed with which the

  5. Mac configuration management at the Los Alamos National Laboratory

    SciTech Connect

    Marcus, Allan B

    2010-01-01

    The Los Alamos National Laboratory (LANL) had a need for central configuration management of non-Windows computers. LANL has three to five thousand Macs and an equal number of Linux based systems. The primary goal was to be able to inventory all non-windows systems and patch Mc OS X systems. LANL examined a number of commercial and open source solutions and ultimately selected Puppet. This paper will discuss why we chose Puppet, how we implemented it, and some lessons we learned along the way.

  6. STS-52 Payload Specialist MacLean during camera training at JSC's MAIL

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-52 Columbia, Orbiter Vehicle (OV) 102, Canadian Payload Specialist Steven G. MacLean practices using a camera for the Earth observations portion of his scheduled October spaceflight. MacLean, standing on the aft flight deck, points a HASSELBLAD camera out overhead window W8 during the training session in JSC's Crew Compartment Trainer (CCT). The CCT is part of the shuttle Mockup and Integration Laboratory (MAIL) Bldg 9NE. MacLean represents the Canadian Space Agency (CSA).

  7. MQ-MAC: a multi-constrained QoS-aware duty cycle MAC for heterogeneous traffic in wireless sensor networks.

    PubMed

    Monowar, Muhammad Mostafa; Rahman, Md Obaidur; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability) within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC). MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency.

  8. MQ-MAC: A Multi-Constrained QoS-Aware Duty Cycle MAC for Heterogeneous Traffic in Wireless Sensor Networks

    PubMed Central

    Monowar, Muhammad Mostafa; Rahman, Md. Obaidur; Hong, Choong Seon; Lee, Sungwon

    2010-01-01

    Energy conservation is one of the striking research issues now-a-days for power constrained wireless sensor networks (WSNs) and hence, several duty-cycle based MAC protocols have been devised for WSNs in the last few years. However, assimilation of diverse applications with different QoS requirements (i.e., delay and reliability) within the same network also necessitates in devising a generic duty-cycle based MAC protocol that can achieve both the delay and reliability guarantee, termed as multi-constrained QoS, while preserving the energy efficiency. To address this, in this paper, we propose a Multi-constrained QoS-aware duty-cycle MAC for heterogeneous traffic in WSNs (MQ-MAC). MQ-MAC classifies the traffic based on their multi-constrained QoS demands. Through extensive simulation using ns-2 we evaluate the performance of MQ-MAC. MQ-MAC provides the desired delay and reliability guarantee according to the nature of the traffic classes as well as achieves energy efficiency. PMID:22163439

  9. Measuring Seebeck Coefficient

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey (Inventor)

    2015-01-01

    A high temperature Seebeck coefficient measurement apparatus and method with various features to minimize typical sources of errors is described. Common sources of temperature and voltage measurement errors which may impact accurate measurement are identified and reduced. Applying the identified principles, a high temperature Seebeck measurement apparatus and method employing a uniaxial, four-point geometry is described to operate from room temperature up to 1300K. These techniques for non-destructive Seebeck coefficient measurements are simple to operate, and are suitable for bulk samples with a broad range of physical types and shapes.

  10. JKTLD: Limb darkening coefficients

    NASA Astrophysics Data System (ADS)

    Southworth, John

    2015-11-01

    JKTLD outputs theoretically-calculated limb darkening (LD) strengths for equations (LD laws) which predict the amount of LD as a function of the part of the star being observed. The coefficients of these laws are obtained by bilinear interpolation (in effective temperature and surface gravity) in published tables of coefficients calculated from stellar model atmospheres by several researchers. Many observations of stars require the strength of limb darkening (LD) to be estimated, which can be done using theoretical models of stellar atmospheres; JKTLD can help in these circumstances.

  11. MacXAFS: An EXAFS analysis package for the Macintosh

    NASA Astrophysics Data System (ADS)

    Bouldin, C.; Furenlid, L.; Elam, T.

    1995-02-01

    We present an EXAFS analysis package that runs on the Apple Macintosh. (Certain commercial products are identified in the article for the sake of completeness. This does not constitute and endorsement by the National Institute of Standards and Technology, the Naval Research Laboratory, or Broohaven National Lab.) The MacXAFS package is derived from a suite of EXAFS analysis programs originally written at the University of Washington. The MacXAFS package preserves the portable computational kernel of this well-tested group of programs and adds a graphical interface by using HyperCard. Communication between the core analysis programs and the HyperCard interface is done by using ASCII script files that direct the execution of the FORTRAN-based analysis programs. The user is largely insulated from the FORTRAN code, but instead interacts with the more intuitive Hypercard interface. This implementation preserves the portability of the ANSI FORTRAN programs, while taking full advantage of the platform-specific user interface features of the Macintosh. Computationally intensive programs, such as the ab initio XAFS calculation program FEFF can be executed remotely via a TCP/IP connection. Due to the clean separation of the interface and the computational kernel, this package is readily extensible by writing new programs, in FORTRAN or any other language, and adding the corresponding interface element in the HyperCard stack.

  12. OsteoMacs: Key players around bone biomaterials.

    PubMed

    Miron, Richard J; Bosshardt, Dieter D

    2016-03-01

    Osteal macrophages (OsteoMacs) are a special subtype of macrophage residing in bony tissues. Interesting findings from basic research have pointed to their vast and substantial roles in bone biology by demonstrating their key function in bone formation and remodeling. Despite these essential findings, much less information is available concerning their response to a variety of biomaterials used for bone regeneration with the majority of investigation primarily focused on their role during the foreign body reaction. With respect to biomaterials, it is well known that cells derived from the monocyte/macrophage lineage are one of the first cell types in contact with implanted biomaterials. Here they demonstrate extremely plastic phenotypes with the ability to differentiate towards classical M1 or M2 macrophages, or subsequently fuse into osteoclasts or multinucleated giant cells (MNGCs). These MNGCs have previously been characterized as foreign body giant cells and associated with biomaterial rejection, however more recently their phenotypes have been implicated with wound healing and tissue regeneration by studies demonstrating their expression of key M2 markers around biomaterials. With such contrasting hypotheses, it becomes essential to better understand their roles to improve the development of osteo-compatible and osteo-promotive biomaterials. This review article expresses the necessity to further study OsteoMacs and MNGCs to understand their function in bone biomaterial tissue integration including dental/orthopedic implants and bone grafting materials.

  13. Improved input parameters for diffusion models of skin absorption.

    PubMed

    Hansen, Steffi; Lehr, Claus-Michael; Schaefer, Ulrich F

    2013-02-01

    To use a diffusion model for predicting skin absorption requires accurate estimates of input parameters on model geometry, affinity and transport characteristics. This review summarizes methods to obtain input parameters for diffusion models of skin absorption focusing on partition and diffusion coefficients. These include experimental methods, extrapolation approaches, and correlations that relate partition and diffusion coefficients to tabulated physico-chemical solute properties. Exhaustive databases on lipid-water and corneocyte protein-water partition coefficients are presented and analyzed to provide improved approximations to estimate lipid-water and corneocyte protein-water partition coefficients. The most commonly used estimates of lipid and corneocyte diffusion coefficients are also reviewed. In order to improve modeling of skin absorption in the future diffusion models should include the vertical stratum corneum heterogeneity, slow equilibration processes, the absorption from complex non-aqueous formulations, and an improved representation of dermal absorption processes. This will require input parameters for which no suitable estimates are yet available.

  14. X-Ray Attenuation Coefficients from 10 Kev to 100 Mev,

    DTIC Science & Technology

    1957-04-30

    fig. 1). A well- shielded detector measures the shells account for most of the absorption by this intensity of the trinsmitted beam, and any photon...narrow-beam measurements ----------------- 2 1.4. Combination of attenuation coefficients -------------------- 2 1.5. Energy absorption...thickness is increased measures the unlikely to be absorbed. Consequently, the ab- total probability of the interaction processes. sorption coefficient

  15. Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

    PubMed

    Hutson, K G; Rogers, L J; Haslett, B G; Boulter, D; Cammack, R

    1978-06-15

    Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.

  16. Monitoring spacecraft atmosphere contaminants by laser absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Steinfeld, J. I.

    1975-01-01

    Data were obtained which will provide a test of the accuracy of the differential absorption method for trace contaminant detection in many-component gas mixtures. The necessary accurate absorption coefficient determinations were carried out for several gases; acetonitrile, 1,2-dichloroethane, Freon-113, furan, methyl ethyl ketone, and t-butyl alcohol. The absorption coefficients are displayed graphically. An opto-acoustic method was tested for measuring absorbance, similar to the system described by Dewey.

  17. Interplay between MacDonald and Hall-Littlewood expansions of extended torus superpolynomials

    NASA Astrophysics Data System (ADS)

    Mironov, A.; Morozov, A.; Shakirov, Sh.; Sleptsov, A.

    2012-05-01

    In [1] extended superpolynomials were introduced for the torus links T [ m, mk + r], which are functions on the entire space of time variables and, at expense of reducing the topological invariance, possess additional algebraic properties, resembling those of the matrix model partition functions and the KP/Toda tau-functions. Not surprisingly, being a suitable extension it actually allows one to calculate the superpolynomials. These functions are defined as expansions into MacDonald polynomials, and their dependence on k is entirely captured by the action of the cut-and-join operator, like in the HOMFLY case. We suggest a simple description of the coefficients in these character expansions, by expanding the initial (at k = 0) conditions for the k-evolution into the new auxiliary basis, this time provided by the Hall-Littlewood polynomials, which, hence, play a role in the description of the dual m-evolution. For illustration we list manifest expressions for a few first series, mk ± 1 , mk ± 2 , mk ± 3 , mk ± 4. Actually all formulas were explicitly tested up to m = 17 strands in the braid.

  18. Two-photon absorption in arsenic sulfide glasses

    NASA Astrophysics Data System (ADS)

    Chunaev, D. S.; Snopatin, G. E.; Plotnichenko, V. G.; Karasik, A. Ya.

    2016-10-01

    The two-photon absorption coefficient of 1047-{\\text{nm}} light in {\\text{As}}35{\\text{S}}65 chalcogenide glass has been measured. CW probe radiation has been used to observe the linear absorption in glass induced by two-photon excitation. The induced absorption lifetime was found to be ∼ 2 {\\text{ms}}.

  19. Comparative study of MacCormack and TVD MacCormack schemes for three-dimensional separation at wing/body junctions in supersonic flows

    NASA Technical Reports Server (NTRS)

    Lakshmanan, Balakrishnan; Tiwari, Surendra N.

    1992-01-01

    A robust, discontinuity-resolving TVD MacCormack scheme containing no dependent parameters requiring adjustment is presently used to investigate the 3D separation of wing/body junction flows at supersonic speeds. Many production codes employing MacCormack schemes can be adapted to use this method. A numerical simulation of laminar supersonic junction flow is found to yield improved separation location predictions, as well as the axial velocity profiles in the separated flow region.

  20. Self-Admitted Pretensions of Mac Users on a Predominantly PC University Campus

    ERIC Educational Resources Information Center

    Firmin, Michael W.; Wood, Whitney L. Muhlenkamp; Firmin, Ruth L.; Wood, Jordan C.

    2010-01-01

    The present qualitative research study addressed the overall research question of college students' pretention dynamics in the context of a university setting. Thirty-five Mac users were interviewed on a university campus that exclusively supports PC machines. Mac users shared four self-admitted pretensions related to using Macintosh computers.…

  1. A Meta-Analytic Review of the MacAndrew Alcoholism Scale.

    ERIC Educational Resources Information Center

    Cooper-Hakim, Amy; Viswesvaran, Chockalingam

    2002-01-01

    Using meta analysis, examined the predictive validity of scores on the MacAndrew Alcoholism Scale (C. MacAndrew, 1965). Compared results for 161 studies with results for 63 studies using cut scores. Discusses why the use of continuous measures rather than cut scores is recommended. (SLD)

  2. Paradox applications integration ATP`s for MAC and mass balance programs

    SciTech Connect

    Russell, V.K.; Mullaney, J.E.

    1994-10-17

    The K Basins Materials Accounting (MAC) and Material Balance (MBA) database system were set up to run under one common applications program. This Acceptance Test Plan (ATP) describes how the code was to be tested to verify its correctness. The scope of the tests is minimal, since both MAC and MBA have already been tested in detail as stand-alone programs.

  3. Morphological evaluation of sperm from infertile men selected by magnetic activated cell sorting (MACS).

    PubMed

    Curti, Gianni; Skowronek, Fernanda; Vernochi, Rita; Rodriguez-Buzzi, Ana Laura; Rodriguez-Buzzi, Juan Carlos; Casanova, Gabriela; Sapiro, Rossana

    2014-12-01

    Electron microscopy analysis performed in five infertile human subjects after sperm selection by swim-up followed by magnetic activated cell sorting (MACS) demonstrated a decrease in the number of spermatozoa with characteristics compatible with cell death. However, no significant differences were found when the swim-up/MACS semen fraction was compared with swim-up fraction alone.

  4. High-Accuracy Compact MacCormack-Type Schemes for Computational Aeroacoustics

    NASA Technical Reports Server (NTRS)

    Hixon, R.; Turkel, E.

    1998-01-01

    Using MacCormack-type methods, a new class of highly accurate compact MacCormack-type schemes is derived which does not require a tridiagonal matrix inversion to obtain the spatial derivatives. Two examples are shown, and results of these schemes for three linear and nonlinear CAA Benchmark Problems are presented.

  5. 33 CFR 165.768 - Security Zone; MacDill Air Force Base, Tampa Bay, FL.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Base, Tampa Bay, FL. 165.768 Section 165.768 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF....768 Security Zone; MacDill Air Force Base, Tampa Bay, FL. (a) Location. The following area is a... title. All waters within Tampa Bay, Florida in the vicinity of MacDill Air Force Base,...

  6. 33 CFR 165.768 - Security Zone; MacDill Air Force Base, Tampa Bay, FL.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Base, Tampa Bay, FL. 165.768 Section 165.768 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF....768 Security Zone; MacDill Air Force Base, Tampa Bay, FL. (a) Location. The following area is a... title. All waters within Tampa Bay, Florida in the vicinity of MacDill Air Force Base,...

  7. 33 CFR 165.768 - Security Zone; MacDill Air Force Base, Tampa Bay, FL.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Base, Tampa Bay, FL. 165.768 Section 165.768 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF....768 Security Zone; MacDill Air Force Base, Tampa Bay, FL. (a) Location. The following area is a... title. All waters within Tampa Bay, Florida in the vicinity of MacDill Air Force Base,...

  8. 77 FR 66375 - Federal Agricultural Mortgage Corporation Funding and Fiscal Affairs; Farmer Mac Investment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-05

    ... not change this definition. D. Section 652.10--Investment Management Farmer Mac commented that several...: Subpart A--Investment Management Sec. 652.1 Purpose. 652.5 Definitions. 652.10 Investment management. 652...; Farmer Mac Investment Management AGENCY: Farm Credit Administration. ACTION: Final rule. SUMMARY:...

  9. Geochemistry and petrography of the MacAlpine Hills lunar meteorites

    NASA Technical Reports Server (NTRS)

    Lindstrom, Marilyn M.; Mckay, David S.; Wentworth, Susan J.; Martinez, Rene R.; Mittlefehldt, David W.; Wang, Ming-Sheng; Lipschutz, Michael E.

    1991-01-01

    MacAlpine Hills 88104 and 88105, anorthositic lunar meteorites recovered form the same area in Antartica, are characterized. Petrographic studies show that MAC88104/5 is a polymict breccia dominated by impact melt clasts. It is better classified as a fragmental breccia than a regolith breccia. The bulk composition is ferroan and highly aluminous (Al2O3-28 percent).

  10. MacAlpine Hills 88104 and 88105 lunar highland meteorites - General description and consortium overview

    NASA Technical Reports Server (NTRS)

    Lindstrom, Marilyn M.; Schwarz, Carol; Score, Roberta; Mason, Brian

    1991-01-01

    MacAlpine Hills 88104 and 88105 meteorites found in nearby locations in Antarctica, which are considered to be pieces of the same meteorite, are described. MAC88104/5 is an anorthositic breccia consisting of numerous small clasts in a glassy matrix. A summary list of lunar meteorites and a review of consortium research are presented.

  11. THE EFFECT OF TEMPERATURE ON THE GROWTH OF MYCOBACTERIUM AVIUM COMPLEX (MAC) ORGANISMS

    EPA Science Inventory

    MAC organisms are able to grow, persist, and colonize in water distribution systems and may amplify in hospital hot water systems. This study examined the response of MAC organisms (M. avium, M. intracellulare, and MX) to a range of temperatures commonly associated with drinking...

  12. Environmental Assessment for Construction/Replacement Military Family Housing- Phase 5 MacDill AFB, Florida

    DTIC Science & Technology

    2003-12-01

    CONTACTED Kevin Gokeman 6 CES/CEC 2610 Pink Flamingo Avenue MacDill AFB, FL 33621 1-813-828-8681 Steve Boyd 6 CES/CEPP 2610 Pink Flamingo ... Flamingo Avenue MacDill AFB, FL 33621 1-813-828-8685 DECEMBER 2003 FINAL 5-1 List of Preparers Environmental Assessment for

  13. [Materials for the substantiation of the biological MAC of benzene].

    PubMed

    Ulanova, I P; Avilova, G G; Karpukhina, E A; Karimova, L K; Boĭko, V I; Makar'eva, L M

    1990-09-01

    Relatively great amount of benzene-originated phenol, the presence of a definite relationship between phenol amount in the urine and benzene content in the air indicate that it is reasonable to use a phenol sample as an exposure test. To determine the intensity of benzene exposure, data on phenol content in the urine of people working at some big-tonnage enterprises has been analyzed. On the basis of the national and foreign literature data on the correlation between the phenol urine concentration and the level of benzene exposure a regression equation was deduced, which has made it possible to calculate phenol content in the urine on the level of average working day benzene concentration adopted in the USSR. This value equals 15 mg/l, which was proposed as a biological benzene MAC.

  14. Interference Analysis Status and Plans for Aeronautical Mobile Airport Communications System (AeroMACS)

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Wilson, Jeffrey D.

    2010-01-01

    Interference issues related to the operation of an aeronautical mobile airport communications system (AeroMACS) in the C-Band (specifically 5091-5150 MHz) is being investigated. The issue of primary interest is co-channel interference from AeroMACS into mobile-satellite system (MSS) feeder uplinks. The effort is focusing on establishing practical limits on AeroMACS transmissions from airports so that the threshold of interference into MSS is not exceeded. The analyses are being performed with the software package Visualyse Professional, developed by Transfinite Systems Limited. Results with omni-directional antennas and plans to extend the models to represent AeroMACS more accurately will be presented. These models should enable realistic analyses of emerging AeroMACS designs to be developed from NASA Test Bed, RTCA 223, and European results.

  15. MicMac GIS application: free open source

    NASA Astrophysics Data System (ADS)

    Duarte, L.; Moutinho, O.; Teodoro, A.

    2016-10-01

    The use of Remotely Piloted Aerial System (RPAS) for remote sensing applications is becoming more frequent as the technologies on on-board cameras and the platform itself are becoming a serious contender to satellite and airplane imagery. MicMac is a photogrammetric tool for image matching that can be used in different contexts. It is an open source software and it can be used as a command line or with a graphic interface (for each command). The main objective of this work was the integration of MicMac with QGIS, which is also an open source software, in order to create a new open source tool applied to photogrammetry/remote sensing. Python language was used to develop the application. This tool would be very useful in the manipulation and 3D modelling of a set of images. The main objective was to create a toolbar in QGIS with the basic functionalities with intuitive graphic interfaces. The toolbar is composed by three buttons: produce the points cloud, create the Digital Elevation Model (DEM) and produce the orthophoto of the study area. The application was tested considering 35 photos, a subset of images acquired by a RPAS in the Aguda beach area, Porto, Portugal. They were used in order to create a 3D terrain model and from this model obtain an orthophoto and the corresponding DEM. The code is open and can be modified according to the user requirements. This integration would be very useful in photogrammetry and remote sensing community combined with GIS capabilities.

  16. 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)

  17. 33 CFR 334.635 - Hillsborough Bay and waters contiguous to MacDill Air Force Base, Fla.; restricted area.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... contiguous to MacDill Air Force Base, Fla.; restricted area. 334.635 Section 334.635 Navigation and Navigable... REGULATIONS § 334.635 Hillsborough Bay and waters contiguous to MacDill Air Force Base, Fla.; restricted area... section shall be enforced by the Commander, MacDill Air Force Base, Florida, and/or such persons...

  18. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Chris Nottoli; Eric Wolfram

    2015-01-01

    The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the diffraction edge effect phenomenon. An investigative test program to measure the absorption properties of highly absorbent melamine foam has been performed at the Riverbank Acoustical Laboratories. This paper will present and discuss the test results relating to the effect of the test materials' surface area, thickness and edge sealing conditions. A follow-on paper is envisioned that will present and discuss the results relating to the spacing between multiple piece specimens, and the mounting condition of the test specimen.

  19. High-Absorption-Efficiency Superlattice Solar Cells by Excitons

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Onomitsu, Koji; Horikoshi, Yoshiji

    2013-11-01

    The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice structures. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of the superlattice solar cells are quite similar to the calculated absorption spectra considering the excitonic effect. The superlattice solar cells are confirmed to have high absorption coefficient compared with the GaAs and AlGaAs bulk solar cells. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells. This effect is more prominent for the solar cells with small absorption layer thicknesses.

  20. Time-dependent oral absorption models

    NASA Technical Reports Server (NTRS)

    Higaki, K.; Yamashita, S.; Amidon, G. L.

    2001-01-01

    The plasma concentration-time profiles following oral administration of drugs are often irregular and cannot be interpreted easily with conventional models based on first- or zero-order absorption kinetics and lag time. Six new models were developed using a time-dependent absorption rate coefficient, ka(t), wherein the time dependency was varied to account for the dynamic processes such as changes in fluid absorption or secretion, in absorption surface area, and in motility with time, in the gastrointestinal tract. In the present study, the plasma concentration profiles of propranolol obtained in human subjects following oral dosing were analyzed using the newly derived models based on mass balance and compared with the conventional models. Nonlinear regression analysis indicated that the conventional compartment model including lag time (CLAG model) could not predict the rapid initial increase in plasma concentration after dosing and the predicted Cmax values were much lower than that observed. On the other hand, all models with the time-dependent absorption rate coefficient, ka(t), were superior to the CLAG model in predicting plasma concentration profiles. Based on Akaike's Information Criterion (AIC), the fluid absorption model without lag time (FA model) exhibited the best overall fit to the data. The two-phase model including lag time, TPLAG model was also found to be a good model judging from the values of sum of squares. This model also described the irregular profiles of plasma concentration with time and frequently predicted Cmax values satisfactorily. A comparison of the absorption rate profiles also suggested that the TPLAG model is better at prediction of irregular absorption kinetics than the FA model. In conclusion, the incorporation of a time-dependent absorption rate coefficient ka(t) allows the prediction of nonlinear absorption characteristics in a more reliable manner.

  1. A cross-layer duty cycle MAC protocol supporting a pipeline feature for wireless sensor networks.

    PubMed

    Tong, Fei; Xie, Rong; Shu, Lei; Kim, Young-Chon

    2011-01-01

    Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency.

  2. A Cross-Layer Duty Cycle MAC Protocol Supporting a Pipeline Feature for Wireless Sensor Networks

    PubMed Central

    Tong, Fei; Xie, Rong; Shu, Lei; Kim, Young-Chon

    2011-01-01

    Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency. PMID:22163895

  3. A tale of two mitochondrial channels, MAC and PTP, in apoptosis.

    PubMed

    Kinnally, Kathleen W; Antonsson, Bruno

    2007-05-01

    The crucial step in the intrinsic, or mitochondrial, apoptotic pathway is permeabilization of the mitochondrial outer membrane. Permeabilization triggers release of apoptogenic factors, such as cytochrome c, from the mitochondrial intermembrane space into the cytosol where these factors ensure propagation of the apoptotic cascade and execution of cell death. However, the mechanism(s) underlying permeabilization of the outer membrane remain controversial. Two mechanisms, involving opening of two different mitochondrial channels, have been proposed to be responsible for the permeabilization; the permeability transition pore (PTP) in the inner membrane and the mitochondrial apoptosis-induced channel (MAC) in the outer membrane. Opening of PTP would lead to matrix swelling, subsequent rupture of the outer membrane, and an unspecific release of intermembrane proteins into the cytosol. However, many believe PTP opening is a consequence of apoptosis and this channel is thought to principally play a role in necrosis, not apoptosis. Activation of MAC is exquisitely regulated by Bcl-2 family proteins, which are the sentinels of apoptosis. MAC provides specific pores in the outer membrane for the passage of intermembrane proteins, in particular cytochrome c, to the cytosol. The electrophysiological characteristics of MAC are very similar to Bax channels and depletion of Bax significantly diminishes MAC activity, suggesting that Bax is an essential constituent of MAC in some systems. The characteristics of various mitochondrial channels and Bax are compared. The involvement of MAC and PTP activities in apoptosis of disease and their pharmacology are discussed.

  4. LFA-1 is sufficient in mediating neutrophil emigration in Mac-1-deficient mice.

    PubMed Central

    Lu, H; Smith, C W; Perrard, J; Bullard, D; Tang, L; Shappell, S B; Entman, M L; Beaudet, A L; Ballantyne, C M

    1997-01-01

    To better define the specific function of Mac-1 (CD11b) versus LFA-1 (CD11a) and the other CD11 integrins in vivo, we have disrupted murine CD11b by targeted homologous recombination in embryonic stem cells and generated mice which are homozygous for a mutation in CD11b. A null mutation was confirmed by Southern blotting, RNase protection assay, immunohistochemistry, and flow cytometry. Neutrophils isolated from mice deficient in Mac-1 were defective in adherence to keyhole limpet hemocyanin-coated glass, iC3b-mediated phagocytosis, and homotypic aggregation. When challenged by thioglycollate intraperitoneally, Mac-1-deficient mice had similar levels of neutrophil accumulation in the peritoneal cavity at 1, 2, and 4 h. Treatment with mAb to LFA-1 blocked 78% of neutrophil accumulation in Mac-1-deficient mice and 58% in wild-type mice. Neutrophil emigration into the peritoneal cavity 16 h after the implantation of fibrinogen-coated disks was not reduced in Mac-1-deficient mice whereas neutrophil adhesion to the fibrinogen-coated disks was reduced by > 90%. Neutrophils from Mac-1-deficient mice also showed reduced degranulation. Our results demonstrate that Mac-1 plays a critical role in mediating binding of neutrophils to fibrinogen and neutrophil degranulation, but is not necessary for effective neutrophil emigration, which is more dependent upon LFA-1. PMID:9077544

  5. A Priority-Based Adaptive MAC Protocol for Wireless Body Area Networks

    PubMed Central

    Bhandari, Sabin; Moh, Sangman

    2016-01-01

    In wireless body area networks (WBANs), various sensors and actuators are placed on/inside the human body and connected wirelessly. WBANs have specific requirements for healthcare and medical applications, hence, standard protocols like the IEEE 802.15.4 cannot fulfill all the requirements. Consequently, many medium access control (MAC) protocols, mostly derived from the IEEE 802.15.4 superframe structure, have been studied. Nevertheless, they do not support a differentiated quality of service (QoS) for the various forms of traffic coexisting in a WBAN. In particular, a QoS-aware MAC protocol is essential for WBANs operating in the unlicensed Industrial, Scientific, and Medical (ISM) bands, because different wireless services like Bluetooth, WiFi, and Zigbee may coexist there and cause severe interference. In this paper, we propose a priority-based adaptive MAC (PA-MAC) protocol for WBANs in unlicensed bands, which allocates time slots dynamically, based on the traffic priority. Further, multiple channels are effectively utilized to reduce access delays in a WBAN, in the presence of coexisting systems. Our performance evaluation results show that the proposed PA-MAC outperforms the IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of the average transmission time, throughput, energy consumption, and data collision ratio. PMID:26999162

  6. A Priority-Based Adaptive MAC Protocol for Wireless Body Area Networks.

    PubMed

    Bhandari, Sabin; Moh, Sangman

    2016-03-18

    In wireless body area networks (WBANs), various sensors and actuators are placed on/inside the human body and connected wirelessly. WBANs have specific requirements for healthcare and medical applications, hence, standard protocols like the IEEE 802.15.4 cannot fulfill all the requirements. Consequently, many medium access control (MAC) protocols, mostly derived from the IEEE 802.15.4 superframe structure, have been studied. Nevertheless, they do not support a differentiated quality of service (QoS) for the various forms of traffic coexisting in a WBAN. In particular, a QoS-aware MAC protocol is essential for WBANs operating in the unlicensed Industrial, Scientific, and Medical (ISM) bands, because different wireless services like Bluetooth, WiFi, and Zigbee may coexist there and cause severe interference. In this paper, we propose a priority-based adaptive MAC (PA-MAC) protocol for WBANs in unlicensed bands, which allocates time slots dynamically, based on the traffic priority. Further, multiple channels are effectively utilized to reduce access delays in a WBAN, in the presence of coexisting systems. Our performance evaluation results show that the proposed PA-MAC outperforms the IEEE 802.15.4 MAC and the conventional priority-based MAC in terms of the average transmission time, throughput, energy consumption, and data collision ratio.

  7. Localization of the membrane attack complex (MAC) in experimental immune complex glomerulonephritis

    PubMed Central

    1983-01-01

    The role of the membrane attack complex (MAC) as a mediator of renal tissue injury was evaluated in rats affected by bovine serum albumin (BSA)-induced immune complex glomerulonephritis. Immunofluorescence studies revealed concurrent deposits of IgG, BSA, C3, and the MAC along glomerular capillary walls, although the MAC manifested a more restricted distribution than that observed for immune complexes. Immunoelectron microscopic techniques were utilized to demonstrate immune complexes, C3, and the MAC within dense deposits in the subepithelial aspect of the basement membrane. Visceral epithelial foot processes were fused in areas overlying large dense deposits and exhibited intense staining for the MAC, lesser reactivity for C3 but IgG was absent from the foot process membranes. Smaller granular deposits of immune complexes, C3, and the MAC were observed in the subendothelial region of the lamina rara interna and the lamina densa. Immune complexes may activate the classical complement pathway causing diffuse injury to the glomerular basement membrane (GBM), allowing subepithelial accumulation of complexes. These observations implicate the MAC as a mediator of GBM and juxtaposed podocyte membrane injury, thereby contributing to disruption of the glomerular filtration barrier. IgG and C3 were demonstrated within tubulointerstitial regions on the surface of collagen fibers in close proximity to the tubular basement membrane (TBM) of proximal convoluted tubules. Within the TBM, C3 localization was prominent with diminished reactivity for the MAC, but IgG was not detectable. The demonstration of C3 and scant MAC deposits in the TBM of nonimmunized control rats without evidence of interstitial IgG and C3 deposits suggests that both nonimmune and immune processes play a role in the pathogenesis of extraglomerular lesions. Evidence derived from these morphologic studies indicates that the MAC is associated with injury to the GBM, foot process membranes of visceral

  8. MAC to VAX Connectivity: Heartrate Spectral Analysis System

    NASA Technical Reports Server (NTRS)

    Rahman, Hasan H.; Faruque, Monazer

    1993-01-01

    The heart rate Spectral Analysis System (SAS) acquires and analyzes, in real-time, the Space Shuttle onboard electrocardiograph (EKG) experiment signals, calculates the heartrate, and applies a Fast Fourier Transformation (FFT) to the heart rate. The system also calculates other statistical parameters such as the 'mean heart rate' over specific time period and heart rate histogram. This SAS is used by NASA Principal Investigators as a research tool to determine the effects of weightlessness on the human cardiovascular system. This is also used to determine if Lower Body Negative Pressure (LBNP) is an effective countermeasure to the orthostatic intolerance experienced by astronauts upon return to normal gravity. In microgravity, astronauts perform the LBNP experiment in the mid deck of the Space Shuttle. The experiment data are downlinked by the orbiter telemetry system, then processed and analyzed in real-time by the integrated Life Sciences Data Acquisition (LSDS) - Spectral Analysis System. The data system is integrated within the framework of two different computer systems, VAX and Macintosh (Mac), using the networking infrastructure to assist the investigators in further understanding the most complex machine on Earth--the human body.

  9. MAC protocol for an ATM-based SuperPON

    NASA Astrophysics Data System (ADS)

    Angelopoulos, John D.; Koulouris, John; Fragoulopoulos, Stratos K.

    1996-11-01

    Developments in optical amplifiers and the tendency towards fewer and larger switching stages made feasible and desirable the concept of SuperPONs with a range of 100km. Up to 15000 residential customers can share the SuperPON on a TDMA basis lowering the cost of access to B-ISDN services. Tree PONs require a MAC protocol to arbitrate the access to upstream slots among the competing customer ATM cells in a dynamic and efficient way. The protocol presented in this work combines different access mechanisms according to service quality requirements. All bursty traffic is manipulated transparently using a reservation approach with closed loop control so as to handle the unpredictability of arrivals. In contrast, voice, N-ISDN and other delay sensitive services are provided with unsolicited access permits. In addition, composite cells offered quasi- synchronous permits are used to support STM legacy traffic without echo-cancellers. So, ABR traffic which is delay tolerant and more cost sensitive, can and should be concentrated with full exploitation of multiplexing gain prospects. The permit distribution algorithm focuses on cell spacing, control of CDV, almost jitter free access for synchronous traffic and efficiency for ABR traffic.

  10. Sandbox for Mac Malware v 1.0

    SciTech Connect

    Walkup, Elizabeth

    2016-05-19

    This software is an analyzer for automated sandbox analysis of malware on the OS X operating system. It runs inside an OS X virtual machine to collect data about what happens when a given file is opened or run. As of August 2014, there was no sandbox software for Mac OS X malware, as it requires different methods from those used on the Windows OS (which most sandboxes are written for). This software adds OS X analysis capabilities to an existing open-source sandbox, Cuckoo Sandbox (http://cuckoosandbox.org/), which previously only worked for Windows. The analyzer itself can take many different types of files as input: the traditional Mach-O and FAT executables, .app files, zip files, Python scripts, Java archives, and web pages, as well as PDFs and other documents. While the file is running, the analyzer also simulates rudimentary human interaction with clicks and mouse movements in order to bypass the tests some malware use to see if they are being analyzed. The analyzer outputs several different kinds of data: function call traces, network captures, screenshots, and all created and modified files. This work also includes a static analysis Cuckoo module for Mach-O binary files. It extracts file structures, code library imports and exports, and signatures. This data can be used along with the analyzer results to create signatures for malware.

  11. Pliable Cognitive MAC for Heterogeneous Adaptive Cognitive Radio Sensor Networks

    PubMed Central

    Ali, Borhanuddin Mohd; Sali, Aduwati

    2016-01-01

    The rapid expansion of wireless monitoring and surveillance applications in several domains reinforces the trend of exploiting emerging technologies such as the cognitive radio. However, these technologies have to adjust their working concepts to consider the common characteristics of conventional wireless sensor networks (WSNs). The cognitive radio sensor network (CRSN), still an immature technology, has to deal with new networks that might have different types of data, traffic patterns, or quality of service (QoS) requirements. In this paper, we design and model a new cognitive radio-based medium access control (MAC) algorithm dealing with the heterogeneous nature of the developed networks in terms of either the traffic pattern or the required QoS for the node applications. The proposed algorithm decreases the consumed power on several fronts, provides satisfactory levels of latency and spectrum utilization with efficient scheduling, and manages the radio resources for various traffic conditions. An intensive performance evaluation is conducted to study the impact of key parameters such as the channel idle time length, node density, and the number of available channels. The performance evaluation of the proposed algorithm shows a better performance than the comparable protocols. Moreover, the results manifest that the proposed algorithm is suitable for real time monitoring applications. PMID:27257964

  12. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    PubMed Central

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L.

    2014-01-01

    The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR) and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC) protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access) for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15%) compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput. PMID:25140339

  13. A MAC Protocol to Support Monitoring of Underwater Spaces.

    PubMed

    Santos, Rodrigo; Orozco, Javier; Ochoa, Sergio F; Meseguer, Roc; Eggly, Gabriel; Pistonesi, Marcelo F

    2016-06-27

    Underwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging.

  14. A MAC Protocol to Support Monitoring of Underwater Spaces †

    PubMed Central

    Santos, Rodrigo; Orozco, Javier; Ochoa, Sergio F.; Meseguer, Roc; Eggly, Gabriel; Pistonesi, Marcelo F.

    2016-01-01

    Underwater sensor networks are becoming an important field of research, because of their everyday increasing application scope. Examples of their application areas are environmental and pollution monitoring (mainly oil spills), oceanographic data collection, support for submarine geolocalization, ocean sampling and early tsunamis alert. The challenge of performing underwater communications is well known, provided that radio signals are useless in this medium, and a wired solution is too expensive. Therefore, the sensors in these networks transmit their information using acoustic signals that propagate well under water. This data transmission type not only brings an opportunity, but also several challenges to the implementation of these networks, e.g., in terms of energy consumption, data transmission and signal interference. In order to help advance the knowledge in the design and implementation of these networks for monitoring underwater spaces, this paper proposes a MAC protocol for acoustic communications between the nodes, based on a self-organized time division multiple access mechanism. The proposal was evaluated using simulations of a real monitoring scenario, and the obtained results are highly encouraging. PMID:27355950

  15. Modified pterional craniotomy without "MacCarty keyhole".

    PubMed

    Moscovici, Samuel; Mizrahi, Cezar José; Margolin, Emil; Spektor, Sergey

    2016-02-01

    Pterional craniotomy is one of the most widely used approaches in neurosurgery. The MacCarty keyhole has remained the preferred means of beginning the craniotomy to achieve a low access point; however, the bone opening may result in a residual defect and an aesthetically unpleasant depression in the periorbital area. We present our modification of the traditional technique. Instead of drilling the keyhole in the frontoperiorbital area, the classical location, we perform a 5 × 15 mm strip craniectomy at the lowest accessible point in the infratemporal fossa, corresponding to the projection of the most lateral point of the sphenoid ridge. The anterior half of this opening exposes the basal frontal dura, while the posterior half brings the temporal dura into view. This modified technique was applied in 48 pterional craniotomies performed for removal of a variety of neoplasms during 2014-2015. There were no approach-related complications. Aesthetic outcomes and patient acceptance have been good; no patient developed skin depression in the periorbital area. In our experience, craniotomy for a pterional approach with the lowest possible access to the frontotemporal skull base may be performed by drilling a narrow oblong opening, without the use of any keyhole or burr hole, to create a smaller skull defect and achieve optimal aesthetic outcomes.

  16. Evaluation of Fourier transform coefficients for the diagnosis of rheumatoid arthritis from diffuse optical tomography images

    NASA Astrophysics Data System (ADS)

    Montejo, Ludguier D.; Jia, Jingfei; Kim, Hyun K.; Hielscher, Andreas H.

    2013-03-01

    We apply the Fourier Transform to absorption and scattering coefficient images of proximal interphalangeal (PIP) joints and evaluate the performance of these coefficients as classifiers using receiver operator characteristic (ROC) curve analysis. We find 25 features that yield a Youden index over 0.7, 3 features that yield a Youden index over 0.8, and 1 feature that yields a Youden index over 0.9 (90.0% sensitivity and 100% specificity). In general, scattering coefficient images yield better one-dimensional classifiers compared to absorption coefficient images. Using features derived from scattering coefficient images we obtain an average Youden index of 0.58 +/- 0.16, and an average Youden index of 0.45 +/- 0.15 when using features from absorption coefficient images.

  17. Adaptive low-power listening MAC protocol based on transmission rates.

    PubMed

    Hwang, Kwang-il; Yi, Gangman

    2014-01-01

    Even though existing low-power listening (LPL) protocols have enabled ultra-low-power operation in wireless sensor networks (WSN), they do not address trade-off between energy and delay, since they focused only on energy aspect. However, in recent years, a growing interest in various WSN applications is requiring new design factors, such as minimum delay and higher reliability, as well as energy efficiency. Therefore, in this paper we propose a novel sensor multiple access control (MAC) protocol, transmission rate based adaptive low-power listening MAC protocol (TRA-MAC), which is a kind of preamble-based LPL but is capable of controlling preamble sensing cycle adaptively to transmission rates. Through experiments, it is demonstrated that TRA-MAC enables LPL cycle (LC) and preamble transmission length to adapt dynamically to varying transmission rates, compensating trade-off between energy and response time.

  18. BIG MAC: A bolometer array for mid-infrared astronomy, Center Director's Discretionary Fund

    NASA Technical Reports Server (NTRS)

    Telesco, C. M.; Decher, R.; Baugher, C.

    1985-01-01

    The infrared array referred to as Big Mac (for Marshall Array Camera), was designed for ground based astronomical observations in the wavelength range 5 to 35 microns. It contains 20 discrete gallium-doped germanium bolometer detectors at a temperature of 1.4K. Each bolometer is irradiated by a square field mirror constituting a single pixel of the array. The mirrors are arranged contiguously in four columns and five rows, thus defining the array configuration. Big Mac utilized cold reimaging optics and an up looking dewar. The total Big Mac system also contains a telescope interface tube for mounting the dewar and a computer for data acquisition and processing. Initial astronomical observations at a major infrared observatory indicate that Big Mac performance is excellent, having achieved the design specifications and making this instrument an outstanding tool for astrophysics.

  19. Austin MacCormick and the Education of Adult Prisoners: Still Relevant Today.

    ERIC Educational Resources Information Center

    Hunsinger, Isabel

    1997-01-01

    Austin MacCormick's 1931 model for correctional education is applicable in today's prisons. It describes the program, facilities, teaching staff, and curriculum, which includes literacy, math, social sciences, health, vocational, social, and cultural education. (SK)

  20. 3. Historic American Buildings Survey, E.P. MacFarland, Photographer April 3, ...

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

    3. Historic American Buildings Survey, E.P. MacFarland, Photographer April 3, 1934, DETAIL OF CORNICE (SOUTH ELEVATION). - St. George's Rectory, Prospect & Greenwich Streets, Hempstead, Nassau County, NY

  1. 5. Historic American Buildings Survey, E.P. MacFarland, Photographer May 1, ...

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

    5. Historic American Buildings Survey, E.P. MacFarland, Photographer May 1, 1934, DETAIL OF MANTEL (PARLOR -- SOUTH WALL). - St. George's Rectory, Prospect & Greenwich Streets, Hempstead, Nassau County, NY

  2. 4. Historic American Buildings Survey, E.P. MacFarland, Photographer May 1, ...

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

    4. Historic American Buildings Survey, E.P. MacFarland, Photographer May 1, 1934, DETAIL OF STAIR (1st STORY -- REAR HALL). - St. George's Rectory, Prospect & Greenwich Streets, Hempstead, Nassau County, NY

  3. Evaluation of video transmission of MAC protocols in wireless sensor network

    NASA Astrophysics Data System (ADS)

    Maulidin, Mahmuddin, M.; Kamaruddin, L. M.; Elsaikh, Mohamed

    2016-08-01

    Wireless Sensor Network (WSN) is a wireless network which consists of sensor nodes scattered in a particular area which are used to monitor physical or environment condition. Each node in WSN is also scattered in sensor field, so an appropriate scheme of MAC protocol should have to develop communication link for data transferring. Video transmission is one of the important applications for the future that can be transmitted with low aspect in side of cost and also power consumption. In this paper, comparison of five different MAC WSN protocol for video transmission namely IEEE 802.11 standard, IEEE 802.15.4 standard, CSMA/CA, Berkeley-MAC, and Lightweight-MAC protocol are studied. Simulation experiment has been conducted in OMNeT++ with INET network simulator software to evaluate the performance. Obtained results indicate that IEEE 802.11 works better than other protocol in term of packet delivery, throughput, and latency.

  4. 4. Historic American Buildings Survey, E.P. MacFarland, Photographer April 23, ...

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

    4. Historic American Buildings Survey, E.P. MacFarland, Photographer April 23, 1934, DETAIL OF MANTEL (LIVING ROOM -- WEST WALL). - Edwin Forrest House, 436 West Twenty-second Street, New York County, NY

  5. 3. Historic American Buildings Survey, E.P. MacFarland, Photographer April 23, ...

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

    3. Historic American Buildings Survey, E.P. MacFarland, Photographer April 23, 1934, DETAIL OF DOORWAY (LIVING ROOM -- NORTH WALL). - Edwin Forrest House, 436 West Twenty-second Street, New York County, NY

  6. 2. Historic American Buildings Survey, E.P. MacFarland, Photographer May 10, ...

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

    2. Historic American Buildings Survey, E.P. MacFarland, Photographer May 10, 1934, DETAIL OF PORTICO (FROM SOUTHWEST). - Old Leake & Watts Orphanage, Amsterdam Avenue & 110th Street, New York County, NY

  7. 2. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, ...

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

    2. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, 1936 SOUTH ELEVATION (FRONT). - Rode-Kothe House, East of U.S. 87 at Cherry Spring, Cherry Spring, Gillespie County, TX

  8. 7. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, ...

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

    7. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, 1936 DETAIL OF STAIR (SOUTH ELEVATION). - Rode-Kothe House, East of U.S. 87 at Cherry Spring, Cherry Spring, Gillespie County, TX

  9. 6. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, ...

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

    6. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, 1936 DETAIL OF STAIR, DOOR AND COLUMNS (SOUTH ELEVATION). - Rode-Kothe House, East of U.S. 87 at Cherry Spring, Cherry Spring, Gillespie County, TX

  10. 8. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, ...

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

    8. Historic American Buildings Survey, Richard MacAllister, Photographer May 29, 1936 INSIDE STAIR (LOOKING SOUTH). - Rode-Kothe House, East of U.S. 87 at Cherry Spring, Cherry Spring, Gillespie County, TX

  11. Industrial WSN Based on IR-UWB and a Low-Latency MAC Protocol

    NASA Astrophysics Data System (ADS)

    Reinhold, Rafael; Underberg, Lisa; Wulf, Armin; Kays, Ruediger

    2016-07-01

    Wireless sensor networks for industrial communication require high reliability and low latency. As current wireless sensor networks do not entirely meet these requirements, novel system approaches need to be developed. Since ultra wideband communication systems seem to be a promising approach, this paper evaluates the performance of the IEEE 802.15.4 impulse-radio ultra-wideband physical layer and the IEEE 802.15.4 Low Latency Deterministic Network (LLDN) MAC for industrial applications. Novel approaches and system adaptions are proposed to meet the application requirements. In this regard, a synchronization approach based on circular average magnitude difference functions (CAMDF) and on a clean template (CT) is presented for the correlation receiver. An adapted MAC protocol titled aggregated low latency (ALL) MAC is proposed to significantly reduce the resulting latency. Based on the system proposals, a hardware prototype has been developed, which proves the feasibility of the system and visualizes the real-time performance of the MAC protocol.

  12. John MacCulloch, MD (1773-1835): a dedicated geologist.

    PubMed

    Hull, Gillian

    2007-11-01

    The teaching in Scottish medical schools in the second half of the 18th century had a reputation that stretched far beyond Britain. Edinburgh attracted students not only for its high academic standards but also for its freedom from religious constraints and its developing interest in the sciences. John MacCulloch was taught at Edinburgh by Joseph Black (1728-99) who had chosen chemistry as a career rather than medicine. Already MacCulloch's enquiring mind ranged over many subjects.

  13. The Macolumn - the Mac gets geophysical. [A review of geophysical software for the Apple Macintosh computer

    SciTech Connect

    Busbey, A.B. )

    1990-02-01

    Seismic Processing Workshop, a program by Parallel Geosciences of Austin, TX, is discussed in this column. The program is a high-speed, interactive seismic processing and computer analysis system for the Apple Macintosh II family of computers. Also reviewed in this column are three products from Wilkerson Associates of Champaign, IL. SubSide is an interactive program for basin subsidence analysis; MacFault and MacThrustRamp are programs for modeling faults.

  14. Evaluation of a High-Accuracy MacCormack-Type Scheme Using Benchmark Problems

    NASA Technical Reports Server (NTRS)

    Hixon, R.

    1997-01-01

    Due to their inherent dissipation and stability, the MacCormack scheme and its variants have been widely used in the computation of unsteady flow and acoustic problems. However, these schemes require many points per wavelength in order to propagate waves with a reasonable amount of accuracy. In this work, the linear wave propagation characteristics of MacCormack-type schemes are shown by solving several of the CAA Benchmark Problems.

  15. The Operational Leadership of General Douglas MacArthur in OPERATION CHROMITE

    DTIC Science & Technology

    2007-11-02

    NAVAL WAR COLLEGE Newport, R.I. The Operational Leadership of General Douglas MacArthur in OPERATION CHROMITE by Judie A. Heineman Commander, United...Operations. The contents of this paper reflect my own personal views and are not necessarily endorsed by the Naval War College or the Department of...MacArthur in Operation Chromite 9. Personal Author: Judie Ann Heineman, Commander, United States Navy 10.Type of Report: FINAL 11. Date of Report: 13

  16. Infrasound absorption by atmospheric clouds

    NASA Astrophysics Data System (ADS)

    Baudoin, Michael; Coulouvrat, Francois; Thomas, Jean-Louis

    2010-05-01

    A model is developed for the absorption of infrasound by atmospheric clouds made of a suspension of liquid water droplets within a gaseous mixture of water vapor and air. The model is based on the work of D.A. Gubaidullin and R.I. Nigmatulin [Int. J. Multiphase Flow, 26, 207-228, 2000], which is applied to atmospheric clouds. Three physical mechanisms are included : unsteady viscous drag associated with momentum transfers due to the translation of water droplets, unsteady thermal transfers between the liquid and gaseous phases, and mass transfers due to the evaporation or condensation of the water phase. For clouds, in the infrasonic frequency range, phase changes are the dominant mechanisms (around 1 Hz), while viscous and heat transfers become significant only around 100 Hz. Mass transfers involve two physical effects : evaporation and condensation of the water phase at the droplet surface, and diffusion of the water vapor within the gaseous phase. The first one is described through the Hertz-Knudsen-Langmuir theory based on kinetic theory. It involves a little known coefficient known as coefficient of accommodation. The second one is the classical Fick diffusion. For clouds, and unless the coefficient of accommodation is very small (far from the generally recommended value is close to one), diffusion is the main limiting effects for mass transfers. In a second stage, the sound and infrasound absorption is evaluated for various typical clouds up to about 4 km altitude. Above this altitude, the ice content of clouds is dominant compared to their water content, and the present model is not applicable. Cloud thickness, water content, and droplets size distribution are shown to be the major factors influencing the infrasound absorption. A variety of clouds have been analyzed. In most cases, it is shown that infrasound absorption within clouds is several orders larger than classical absorption (due to molecular relaxation of nitrogen and oxygen molecules in presence

  17. Delayed wound healing in Mac-1-deficient mice is associated with normal monocyte recruitment.

    PubMed

    Sisco, Mark; Chao, Jerome D; Kim, Injoong; Mogford, Jon E; Mayadas, Tanya N; Mustoe, Thomas A

    2007-01-01

    The Mac-1 integrin is an important mediator of migration and inflammatory activation of neutrophils and monocytes. However, the role of Mac-1 in modulating macrophage emigration and activation and its subsequent impact on cutaneous wound healing have not been fully elucidated. To examine the significance of Mac-1 to murine wound healing, we measured epithelialization and granulation tissue formation in partial-thickness ear wounds and full-thickness head wounds, respectively, in Mac-1-deficient mice. Wounds were histologically analyzed at postwounding days 3, 5, and 7. The gap measured between the leading edges of inward-migrating granulation tissue was significantly increased in knockout mice compared with control animals at day 5 (3.8+/-0.3 vs. 2.6+/-0.5 mm; p<0.001) and day 7 (2.2+/-0.4 vs. 0.96+/-0.73 mm; p=0.005). Epithelial gap measurements were also increased in knockout mice vs. wild-type controls at days 3 (0.62+/-0.02 vs. 0.54+/-0.07 mm; p<0.05) and 5 (0.58+/-0.06 vs. 0.39+/-0.08 mm; p<0.001). Immunohistochemistry showed equal numbers of macrophages in knockout and control wounds. These findings show that Mac-1 is required for normal wound healing but that the attenuation in the deposition of granulation tissue and wound epithelialization in Mac-1 knockout mice is not associated with decreased monocyte migration into the wound.

  18. Considerations for Improving the Capacity and Performance of AeroMACS

    NASA Technical Reports Server (NTRS)

    Kerczewski, Robert J.; Kamali, Behnam; Apaza, Rafael D.; Wilson, Jeffrey D.; Dimond, Robert P.

    2014-01-01

    The Aeronautical Mobile Airport Communications System (AeroMACS) has progressed from concept through prototype development, testing, and standards development and is now poised for the first operational deployments at nine US airports by the Federal Aviation Administration. These initial deployments will support fixed applications. Mobile applications providing connectivity to and from aircraft and ground-based vehicles on the airport surface will occur at some point in the future. Given that many fixed applications are possible for AeroMACS, it is necessary to now consider whether the existing capacity of AeroMACS will be reached even before the mobile applications are ready to be added, since AeroMACS is constrained by both available bandwidth and transmit power limitations. This paper describes some concepts that may be applied to improve the future capacity of AeroMACS, with a particular emphasis on gains that can be derived from the addition of IEEE 802.16j multihop relays to the AeroMACS standard, where a significant analysis effort has been undertaken.

  19. Functional implications of an intermeshing cogwheel-like interaction between TolC and MacA in the action of macrolide-specific efflux pump MacAB-TolC.

    PubMed

    Xu, Yongbin; Song, Saemee; Moeller, Arne; Kim, Nahee; Piao, Shunfu; Sim, Se-Hoon; Kang, Mooseok; Yu, Wookyung; Cho, Hyun-Soo; Chang, Iksoo; Lee, Kangseok; Ha, Nam-Chul

    2011-04-15

    Macrolide-specific efflux pump MacAB-TolC has been identified in diverse gram-negative bacteria including Escherichia coli. The inner membrane transporter MacB requires the outer membrane factor TolC and the periplasmic adaptor protein MacA to form a functional tripartite complex. In this study, we used a chimeric protein containing the tip region of the TolC α-barrel to investigate the role of the TolC α-barrel tip region with regard to its interaction with MacA. The chimeric protein formed a stable complex with MacA, and the complex formation was abolished by substitution at the functionally essential residues located at the MacA α-helical tip region. Electron microscopic study delineated that this complex was made by tip-to-tip interaction between the tip regions of the α-barrels of TolC and MacA, which correlated well with the TolC and MacA complex calculated by molecular dynamics. Taken together, our results demonstrate that the MacA hexamer interacts with TolC in a tip-to-tip manner, and implies the manner by which MacA induces opening of the TolC channel.

  20. Identification of a copper-induced intramolecular interaction in the transcription factor Mac1 from Saccharomyces cerevisiae.

    PubMed Central

    Jensen, L T; Winge, D R

    1998-01-01

    Mac1 mediates copper (Cu)-dependent expression of genes involved in high-affinity uptake of copper ions in Saccharomyces cerevisiae. Mac1 is a transcriptional activator in Cu-deficient cells, but is inhibited in Cu-replete cells. Mac1 resides within the nucleus in both Cu-deficient and Cu-loaded cells. Cu inhibition of Mac1 appears to result from binding of eight copper ions within a C-terminal segment consisting of two Cys-rich motifs. In addition, two zinc ions are bound within the N-terminal DNA-binding domain. Only 4-5 mol. eq. Cu are bound to a mutant Mac1 (His279Gln substitution) that is impervious to Cu inhibition. The CuMac1 complex is luminescent, indicative of copper bound in the Cu(I) state. Cu binding induces a molecular switch resulting in an intramolecular interaction in Mac1 between the N-terminal DNA-binding domain and the C-terminal activation domain. This allosteric interaction is Cu dependent and is not observed when Mac1 contained the mutant His279Gln substitution. Fusion of the minimal DNA-binding domain of Mac1 (residues 1-159) to the minimal Cu-binding activation domain (residues 252-341) yields a functional Cu-regulated transcriptional activator. These results suggest that Cu repression of Mac1 arises from a Cu-induced intramolecular interaction that inhibits both DNA binding and transactivation activities. PMID:9736617

  1. 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.

  2. Coefficient Alpha: A Reliability Coefficient for the 21st Century?

    ERIC Educational Resources Information Center

    Yang, Yanyun; Green, Samuel B.

    2011-01-01

    Coefficient alpha is almost universally applied to assess reliability of scales in psychology. We argue that researchers should consider alternatives to coefficient alpha. Our preference is for structural equation modeling (SEM) estimates of reliability because they are informative and allow for an empirical evaluation of the assumptions…

  3. On Proper Selection of Multihop Relays for Future Enhancement of AeroMACS Networks

    NASA Technical Reports Server (NTRS)

    Kamali, Behnam; Kerczewski, Robert J.; Apaza, Rafael D.

    2015-01-01

    As the Aeronautical Mobile Airport Communications System (AeroMACS) has evolved from a technology concept to a deployed communications network over major US airports, it is now time to contemplate whether the existing capacity of AeroMACS is sufficient to meet the demands set forth by all fixed and mobile applications over the airport surface given the AeroMACS constraints regarding bandwidth and transmit power. The underlying idea in this article is to present IEEE 802.16j-based WiMAX as a technology that can address future capacity enhancements and therefore is most feasible for AeroMACS applications. The principal argument in favor IEEE 802.16j technology is the flexible and cost effective extension of radio coverage that is afforded by relay fortified networks, with virtually no increase in the power requirements and virtually no rise in interference levels to co-allocated applications. The IEEE 802.16j-based multihop relay systems are briefly described. The focus is on key features of this technology, frame structure, and its architecture. Next, AeroMACS is described as a WiMAX-based wireless network. The two major relay modes supported by IEEE 802.16j amendment, i.e., transparent and non-transparent are described. The benefits of employing multihop relays are listed. Some key challenges related to incorporating relays into AeroMACS networks are discussed. The selection of relay type in a broadband wireless network affects a number of network parameters such as latency, signal overhead, PHY (Scalable Physical Layer) and MAC (Media Access Layer) layer protocols, consequently it can alter key network quantities of throughput and QoS (Quality of Service).

  4. Characterization of the Murine Myeloid Precursor Cell Line MuMac-E8

    PubMed Central

    Fricke, Stephan; Riemschneider, Sina; Kohlschmidt, Janine; Hilger, Nadja; Fueldner, Christiane; Knauer, Jens; Sack, Ulrich; Emmrich, Frank; Lehmann, Jörg

    2014-01-01

    Starting point for the present work was the assumption that the cell line MuMac-E8 represents a murine cell population with stem cell properties. Preliminary studies already pointed to the expression of stem-cell associated markers and a self-regenerative potential of the cells. The cell line MuMac-E8 should be examined for their differential stage within stem cell hierarchy. MuMac-E8 cells were derived from a chimeric mouse model of arthritis. It could be shown that MuMac-E8 cells express mRNA of some genes associated with pluripotent stem cells (Nanog, Nucleostemin), of genes for hematopoietic markers (EPCR, Sca-1, CD11b, CD45), for the mesenchymal marker CD105 and of genes for the neural markers Pax-6 and Ezrin. In methylcellulose and May-Grünwald-Giemsa staining, hematopoietic colonies were obtained but the hematopoietic system of lethally irradiated mice could not be rescued. Osteogenic differentiation was not detectable. Thus, it became evident that MuMac-E8 represents not a stem cell line. However, MuMac-E8 cells expressed several myeloid surface markers (i.e. CD11b, F4/80, CD14, CD64), showed phagocytosis and is capable of producing nitric oxide. Thus, this cell line seems to be arrested an advanced stage of myeloid differentiation. Adherence data measured by impedance-based real-time cell analysis together with cell morphology data suggested that MuMac-E8 represents a new macrophage precursor cell line exhibiting weak adherence. This cell line is suitable as an in-vitro model for testing of macrophage functions. Moreover, it might be also useful for differentiation or reprogramming studies. PMID:25546418

  5. An energy-efficient MAC protocol using dynamic queue management for delay-tolerant mobile sensor networks.

    PubMed

    Li, Jie; Li, Qiyue; Qu, Yugui; Zhao, Baohua

    2011-01-01

    Conventional MAC protocols for wireless sensor network perform poorly when faced with a delay-tolerant mobile network environment. Characterized by a highly dynamic and sparse topology, poor network connectivity as well as data delay-tolerance, delay-tolerant mobile sensor networks exacerbate the severe power constraints and memory limitations of nodes. This paper proposes an energy-efficient MAC protocol using dynamic queue management (EQ-MAC) for power saving and data queue management. Via data transfers initiated by the target sink and the use of a dynamic queue management strategy based on priority, EQ-MAC effectively avoids untargeted transfers, increases the chance of successful data transmission, and makes useful data reach the target terminal in a timely manner. Experimental results show that EQ-MAC has high energy efficiency in comparison with a conventional MAC protocol. It also achieves a 46% decrease in packet drop probability, 79% increase in system throughput, and 25% decrease in mean packet delay.

  6. Triple effect absorption chiller utilizing two refrigeration circuits

    DOEpatents

    DeVault, Robert C.

    1988-01-01

    A triple effect absorption method and apparatus having a high coefficient of performance. Two single effect absorption circuits are combined with heat exchange occurring between a condenser and absorber of a high temperature circuit, and a generator of a low temperature circuit. The evaporators of both the high and low temperature circuits provide cooling to an external heat load.

  7. Multiplication of different Legionella species in Mono Mac 6 cells and in Acanthamoeba castellanii.

    PubMed Central

    Neumeister, B; Schöniger, S; Faigle, M; Eichner, M; Dietz, K

    1997-01-01

    Survival and distribution of legionellae in the environment are assumed to be associated with their multiplication in amoebae, whereas the ability to multiply in macrophages is usually regarded to correspond to pathogenicity. Since most investigations focused on Legionella pneumophila serogroup 1, we examined the intracellular multiplication of different Legionella species in Mono Mac 6 cells, which express phenotypic and functional features of mature monocytes, and in Acanthamoeba castellanii, an environmental host of Legionella spp. According to the bacterial doubling time in Mono Mac 6 cells and in A. castellanii, seven clusters of legionellae could be defined which could be split further with regard to finer differences. L. longbeachae serogroup 1, L. jordanis, and L. anisa were not able to multiply in either A. castellanii or Mono Mac 6 cells and are members of the first cluster. L. dumoffi did not multiply in Mono Mac 6 cells but showed a delayed multiplication in A. castellanii 72 h after infection and is the only member of the second cluster. L. steigerwaltii, L. gormanii, L. pneumophila serogroup 6 ATCC 33215, L. bozemanii, and L. micdadei showed a stable bacterial count in Mono Mac 6 cells after infection but a decreasing count in amoebae. They can be regarded as members of the third cluster. As the only member of the fourth cluster, L. oakridgensis was able to multiply slight in Mono Mac 6 cells but was killed within amoebae. A strain of L. pneumophila serogroup 1 Philadelphia obtained after 30 passages on SMH agar and a strain of L. pneumophila serogroup 1 Philadelphia obtained after intraperitoneal growth in guinea pigs are members of the fifth cluster, which showed multiplication in Mono Mac 6 cells but a decrease of bacterial counts in A. castellanii. The sixth cluster is characterized by intracellular multiplication in both host cell systems and consists of several strains of L. pneumophila serogroup 1 Philadelphia, a strain of L. pneumophila

  8. Low-Absorption Liquid Crystals for Infrared Beam Steering

    DTIC Science & Technology

    2014-10-17

    goals are: ri~0.2 (at-tSilri),*? (at 1 kHz), and absorption coefficient B 5/cm. 15. SUBJECT TERMS Low absorption, MWIR, chlorinated liquid crystals...spectral region of interest by deuteration, fluorination and chlorination ; 2) Employing thin cell gap by choosing a high birefringence liquid crystal...mixture. First, we synthesized several chlorinated terphenyls and made a eutectic mixture showing a low absorption window in the region of 4-5|a.m

  9. Geospatial Multi-Agency Coordination (GeoMAC) wildland fire perimeters, 2008

    USGS Publications Warehouse

    Walters, Sandra P.; Schneider, Norma J.; Guthrie, John D.

    2011-01-01

    The Geospatial Multi-Agency Coordination (GeoMAC) has been collecting and storing data on wildland fire perimeters since August 2000. The dataset presented via this U.S. Geological Survey Data Series product contains the GeoMAC wildland fire perimeter data for the calendar year 2008, which are based upon input from incident intelligence sources, Global Positioning System (GPS) data, and infrared (IR) imagery. Wildland fire perimeter data are obtained from the incidents, evaluated for completeness and accuracy, and processed to reflect consistent field names and attributes. After a quality check, the perimeters are loaded to GeoMAC databases, which support the GeoMAC Web application for access by wildland fire managers and the public. The wildland fire perimeters are viewed through the Web application. The data are subsequently archived according to year and state and are made available for downloading through the Internet in shapefile and Keyhole Markup Language (KML) format. These wildland fire perimeter data are also retained for historical, planning, and research purposes. The datasets that pertain to this report can be found on the Rocky Mountain Geographic Science Center HTTP site at http://rmgsc.cr.usgs.gov/outgoing/GeoMAC/historic_fire_data/. The links are also provided on the sidebar.

  10. Crystallization and preliminary X-ray crystallographic analysis of MacA from Actinobacillus actinomycetemcomitans

    SciTech Connect

    Piao, Shunfu; Xu, Yongbin; Ha, Nam-Chul

    2008-05-01

    A periplasmic membrane-fusion protein MacA from Actinobacillus actinomycetemcomitans, an essential component of the multidrug efflux pump in Gram-negative bacteria, was crystallized. Periplasmic membrane-fusion proteins (MFPs) are an essential component of the multidrug efflux pump in Gram-negative bacteria. They play a crucial role in bridging the outer membrane porin TolC and two distinct types of inner membrane transporters. The MFP MacA bridges the inner membrane ABC-type multidrug transporter MacB and the outer membrane porin TolC. MacA from the pathogenic bacterium Actinobacillus actinomycetemcomitans was expressed in Escherichia coli B834 (DE3) and the recombinant protein was purified using Ni–NTA affinity, Q anion-exchange and gel-filtration chromatography. The purified MacA protein was crystallized using the vapour-diffusion method. A MAD diffraction data set was collected to a resolution of 3.0 Å at 100 K. The crystal belongs to space group P622, with unit-cell parameters a = b = 109.2, c = 255.4 Å, α = β = 90, γ = 120°, and contains one molecule in the asymmetric unit.

  11. Eliminating the Heart from the Curcumin Molecule: Monocarbonyl Curcumin Mimics (MACs)

    PubMed Central

    Shetty, Dinesh; Kim, Yong Joon; Shim, Hyunsuk; Snyder, James P.

    2015-01-01

    Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs). A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK) profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria. PMID:25547726

  12. Implementation of a reference management system, MacRefer, under HyperCard.

    PubMed

    Sato, H; Sato, S; Horikoshi, I

    1996-06-01

    We have developed a reference management system, MacRefer, using HyperTalk on Macintosh personal computers. Using this program, one can automatically acquire data from databases created by EndNote Plus and from OVID- or Medlar-formatted records downloaded via an online use of Medline. The MacRefer's capability of formatting bibliographic database in user-defined formats is comparable with the exemplified bibliography maker, EndNote Plus. Moreover, MacRefer has several competitive features, which are insufficiently equipped with EndNote Plus. For example, MacRefer is capable of (1) maintaining subsets within a database, (2) executing complex, structured searches combining up to nine keywords for any data field with the results and search conditions preserved, and (3) easily browsing (a portion of) reference database. Although MacRefer cannot be recognized as an absolute alternative of EndNote Plus because of several limitations inherent to HyperCard, the compensatory use of these two programs will expand the personal utilization of bibliographic databases.

  13. A Power-Optimized Cooperative MAC Protocol for Lifetime Extension in Wireless Sensor Networks.

    PubMed

    Liu, Kai; Wu, Shan; Huang, Bo; Liu, Feng; Xu, Zhen

    2016-10-01

    In wireless sensor networks, in order to satisfy the requirement of long working time of energy-limited nodes, we need to design an energy-efficient and lifetime-extended medium access control (MAC) protocol. In this paper, a node cooperation mechanism that one or multiple nodes with higher channel gain and sufficient residual energy help a sender relay its data packets to its recipient is employed to achieve this objective. We first propose a transmission power optimization algorithm to prolong network lifetime by optimizing the transmission powers of the sender and its cooperative nodes to maximize their minimum residual energy after their data packet transmissions. Based on it, we propose a corresponding power-optimized cooperative MAC protocol. A cooperative node contention mechanism is designed to ensure that the sender can effectively select a group of cooperative nodes with the lowest energy consumption and the best channel quality for cooperative transmissions, thus further improving the energy efficiency. Simulation results show that compared to typical MAC protocol with direct transmissions and energy-efficient cooperative MAC protocol, the proposed cooperative MAC protocol can efficiently improve the energy efficiency and extend the network lifetime.

  14. A Study on Energy Efficient MAC Protocol of Wireless Sensor Network for Ubiquitous Agriculture

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Chul; Lee, Ji-Woong; Hwang, Jeong-Hwan; Yoe, Hyun

    Various technologies are used in the agricultural sites now. Especially, the recent application of sensor network related technology is quite notable. Considering the efficiency of MAC protocol of WSN is being researched in various aspects, it is believed that a research on how to apply the MAC protocol to agriculture would be also required. This research is based on the sensor node developed by Sunchon University ITRC. Once the sensor nodes are effectively located in the farm, they operate for a long time and they are rarely relocated once installed. The concentration of multiple sensor nodes in a narrow area is another characteristic the sensor node. The purpose of this research is to select a sensor network MAC protocol, which would be most proper to agricultural site with good energy efficiency and excellent transmission delay performance. The applicable protocols such as S-MAC and X-MAC were set up for the installation environment. They were compared and a methodology to select the most optimum protocol to agricultural site is suggested.

  15. Halothane concentrations required to block the cardiovascular responses to incision (MAC CVR) in infants and children.

    PubMed

    Ishizawa, Y; Dohi, S

    1993-01-01

    The purpose of this study was to determine the halothane concentration in N2O required to block the cardiovascular responses to skin incision (MAC CVR) in infants and children. We studied 64 unpremedicated ASA 1 infants and children (one month to seven years). In each infant or child, anaesthesia was induced slowly with halothane and N2O, and an endotracheal tube was placed. The MAC CVR was assessed, after a steady state end-tidal halothane concentration had been established for ten minutes, by the "up and down technique" of Dixon. Positive responses were defined as an increase in MAP or HR > 10%. The MAC CVR50 values of halothane with 60% N2O were 1.16 +/- 0.23% at 1-6 mo, 1.17 +/- 0.18% at 7-12 mo, 0.95 +/- 0.26% at 1-3 yr, and 1.12 +/- 0.16% at 4-7 yr. The value at 1-3 years children was less than those in the other age groups (P < 0.05). The changes of MAP were correlated with changes of both HR and pupillary diameter. These results indicate that the values of MAC CVR50 of halothane in infants and children are higher than those required to block motor responses (MAC). The halothane requirement to block cardiovascular responses is lowest in the children aged one to three years.

  16. Magnetic-activated cell sorting (MACS) significantly decreases the hybridization efficiency of fluorescence in situ hybridization (FISH).

    PubMed

    Kuo, P L; Guo, H R

    2001-05-01

    Fetal cells were enriched from maternal blood using density gradient centrifugation of Histopaque followed by magnetic-activated cell sorting (MACS) to select CD71-positive cells. For each specimen, cells partially purified by Histopaque were split into equal portions, and each portion was subjected to purification by MACS in parallel. Cells before and after MACS were subjected to dual-color fluorescence in situ hybridization (FISH) analysis with X- and Y-chromosome-specific probes. We found that the hybridization rates were decreased by approximately 10% after MACS based on duplicated analysis for each sample.

  17. Detection of constitutive heterodimerization of the integrin Mac-1 subunits by fluorescence resonance energy transfer in living cells

    SciTech Connect

    Fu Guo; Yang Huayan; Wang Chen; Zhang Feng; You Zhendong; Wang Guiying; He Cheng; Chen Yizhang . E-mail: yzchen0928@yahoo.com; Xu Zhihan . E-mail: zzxu@mail.shcnc.ac.cn

    2006-08-04

    Macrophage differentiation antigen associated with complement three receptor function (Mac-1) belongs to {beta}{sub 2} subfamily of integrins that mediate important cell-cell and cell-extracellular matrix interactions. Biochemical studies have indicated that Mac-1 is a constitutive heterodimer in vitro. Here, we detected the heterodimerization of Mac-1 subunits in living cells by means of two fluorescence resonance energy transfer (FRET) techniques (fluorescence microscopy and fluorescence spectroscopy) and our results demonstrated that there is constitutive heterodimerization of the Mac-1 subunits and this constitutive heterodimerization of the Mac-1 subunits is cell-type independent. Through FRET imaging, we found that heterodimers of Mac-1 mainly localized in plasma membrane, perinuclear, and Golgi area in living cells. Furthermore, through analysis of the estimated physical distances between cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) fused to Mac-1 subunits, we suggested that the conformation of Mac-1 subunits is not affected by the fusion of CFP or YFP and inferred that Mac-1 subunits take different conformation when expressed in Chinese hamster ovary (CHO) and human embryonic kidney (HEK) 293T cells, respectively.

  18. Comparing McGRATH® MAC, C-MAC®, and Macintosh Laryngoscopes Operated by Medical Students: A Randomized, Crossover, Manikin Study

    PubMed Central

    Shin, Myungju; Lee, Ki-Young

    2016-01-01

    We hypothesized that the McGRATH MAC would decrease the time of intubation compared to C-MAC for novices. Thirty-nine medical students who had used the Macintosh blade to intubate a manikin fewer than 3 times were recruited. The participants performed sequential intubations on the manikin in two simulated settings that included a normal airway and a difficult airway (tongue edema). The intubation time, success rate of intubation, Cormack-Lehane grade at laryngoscopy, and difficulty using the device were recorded. Each participant was asked to identify the device that was most useful. The intubation time decreased significantly and by a similar amount to the McGRATH MAC and C-MAC compared to the Macintosh blade (P < 0.001 and P = 0.017, resp.). In the difficult airway, the intubation times were similar among the three devices. The McGRATH MAC and C-MAC significantly increased the success rate of intubation, improved the Cormack-Lehane grade, and decreased the difficulty score compared to the Macintosh blade in both airway settings. The majority of participants selected the McGRATH MAC as the most useful device. The McGRATH MAC and C-MAC may offer similar benefits for intubation compared to the Macintosh blade in normal and difficult airway situations. PMID:27703983

  19. The saturable absorption and reverse saturable absorption properties of Cu doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Yao, Cheng-Bao; Wen, Xin; Li, Qiang-Hua; Yan, Xiao-Yan; Li, Jin; Zhang, Ke-Xin; Sun, Wen-Jun; Bai, Li-Na; Yang, Shou-Bin

    2017-03-01

    We present the structure and nonlinear absorption (NLA) properties of Cu-doped ZnO (CZO) films prepared by magnetron sputtering. The films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the CZO films can maintain a wurtzite structure. Furthermore, the open-aperture (OA) Z-scan measurements of the film were carried out by nanosecond laser pulse. A transition from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the excitation intensity increasing. With good excellent nonlinear optical coefficient, the samples were expected to be the potential applications in optical devices.

  20. Some Improvements in Confidence Intervals for Standardized Regression Coefficients.

    PubMed

    Dudgeon, Paul

    2017-03-13

    Yuan and Chan (Psychometrika 76:670-690, 2011. doi: 10.1007/S11336-011-9224-6 ) derived consistent confidence intervals for standardized regression coefficients under fixed and random score assumptions. Jones and Waller (Psychometrika 80:365-378, 2015. doi: 10.1007/S11336-013-9380-Y ) extended these developments to circumstances where data are non-normal by examining confidence intervals based on Browne's (Br J Math Stat Psychol 37:62-83, 1984. doi: 10.1111/j.2044-8317.1984.tb00789.x ) asymptotic distribution-free (ADF) theory. Seven different heteroscedastic-consistent (HC) estimators were investigated in the current study as potentially better solutions for constructing confidence intervals on standardized regression coefficients under non-normality. Normal theory, ADF, and HC estimators were evaluated in a Monte Carlo simulation. Findings confirmed the superiority of the HC3 (MacKinnon and White, J Econ 35:305-325, 1985. doi: 10.1016/0304-4076(85)90158-7 ) and HC5 (Cribari-Neto and Da Silva, Adv Stat Anal 95:129-146, 2011. doi: 10.1007/s10182-010-0141-2 ) interval estimators over Jones and Waller's ADF estimator under all conditions investigated, as well as over the normal theory method. The HC5 estimator was more robust in a restricted set of conditions over the HC3 estimator. Some possible extensions of HC estimators to other effect size measures are considered for future developments.

  1. Cytoplasmic hydrogen ion diffusion coefficient.

    PubMed Central

    al-Baldawi, N F; Abercrombie, R F

    1992-01-01

    The apparent cytoplasmic proton diffusion coefficient was measured using pH electrodes and samples of cytoplasm extracted from the giant neuron of a marine invertebrate. By suddenly changing the pH at one surface of the sample and recording the relaxation of pH within the sample, an apparent diffusion coefficient of 1.4 +/- 0.5 x 10(-6) cm2/s (N = 7) was measured in the acidic or neutral range of pH (6.0-7.2). This value is approximately 5x lower than the diffusion coefficient of the mobile pH buffers (approximately 8 x 10(-6) cm2/s) and approximately 68x lower than the diffusion coefficient of the hydronium ion (93 x 10(-6) cm2/s). A mobile pH buffer (approximately 15% of the buffering power) and an immobile buffer (approximately 85% of the buffering power) could quantitatively account for the results at acidic or neutral pH. At alkaline pH (8.2-8.6), the apparent proton diffusion coefficient increased to 4.1 +/- 0.8 x 10(-6) cm2/s (N = 7). This larger diffusion coefficient at alkaline pH could be explained quantitatively by the enhanced buffering power of the mobile amino acids. Under the conditions of these experiments, it is unlikely that hydroxide movement influences the apparent hydrogen ion diffusion coefficient. PMID:1617134

  2. Millimeter and submillimeter wave absorption by atmospheric pollutants and constituents

    NASA Astrophysics Data System (ADS)

    Kolbe, W. F.; Leskovar, B.

    1981-10-01

    Calculated absorption coefficients and rotational transition frequencies are given for a number of polar molecules of interest to pollution and energy research. The results, which are presented in graphical form for microwave frequencies up to 1400 GHz, illustrate the increased absorption line intensities occurring in the submillimeter region. For most species these absorption coefficients attain their maximum values in this region. Included in the calculations are the gases SO2, H2CO, O3, H2O, H2S, OCS, CO, NO, OH, SO, NH3, and CS. A discussion of the techniques currently available for the detection in the submillimeter region of these species is also given.

  3. Phononic glass: a robust acoustic-absorption material.

    PubMed

    Jiang, Heng; Wang, Yuren

    2012-08-01

    In order to achieve strong wide band acoustic absorption under high hydrostatic pressure, an interpenetrating network structure is introduced into the locally resonant phononic crystal to fabricate a type of phononic composite material called "phononic glass." Underwater acoustic absorption coefficient measurements show that the material owns high underwater sound absorption coefficients over 0.9 in 12-30 kHz. Moreover, the quasi-static compressive behavior shows that the phononic glass has a compressive strength over 5 MPa which is crucial for underwater applications.

  4. Optimal sensor placement for maximum area coverage (MAC) for damage localization in composite structures

    NASA Astrophysics Data System (ADS)

    Thiene, M.; Sharif Khodaei, Z.; Aliabadi, M. H.

    2016-09-01

    In this paper an optimal sensor placement algorithm for attaining the maximum area coverage (MAC) within a sensor network is presented. The proposed novel approach takes into account physical properties of Lamb wave propagation (attenuation profile, direction dependant group velocity due to material anisotropy) and geometrical complexities (boundary reflections, presence of openings) of the structure. A feature of the proposed optimization approach lies in the fact that it is independent of characteristics of the damage detection algorithm (e.g. probability of detection) making it readily up-scalable to large complex composite structures such as aircraft stiffened composite panel. The proposed fitness function (MAC) is independent of damage parameters (type, severity, location). Statistical analysis carried out shows that the proposed optimum sensor network with MAC results in high probability of damage localization. Genetic algorithm is coupled with the fitness function to provide an efficient optimization strategy.

  5. An Energy-Efficient Mobility-Supporting MAC Protocol for Mobile Sensor Networks

    NASA Astrophysics Data System (ADS)

    Choi, Sung-Chan; Lee, Jang-Won

    In this paper, we design an adaptive mobility-supporting MAC (AM-MAC) protocol for mobile sensor networks. In our protocol, as in S-MAC [1], each virtual cluster that consists of a subset of sensor nodes has its own listen-sleep schedule. Hence, when a mobile sensor node moves into a new virtual cluster, it needs to adapt to the listen-sleep schedule of the corresponding virtual cluster in a timely and energy efficient manner. To this end, in our protocol, we utilize schedule information on border nodes between virtual clusters. This allows us to implement fast and energy efficient listen-sleep schedule adaptation for mobile nodes, which consists of two main functions: energy efficient secondary listen period and smart scheduling adaptation. Simulation results show that our protocol can provide fast schedule adaptation while achieving energy efficiency.

  6. AeroMACS C-Band Interference Modeling and Simulation Results

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey

    2010-01-01

    A new C-band (5091-5150 MHz) airport communications system designated as Aeronautical Mobile Airport Communications System (AeroMACS) is being planned under the Federal Aviation Administration s NextGen program. It is necessary to establish practical limits on AeroMACS transmission power from airports so that the threshold of interference into the Mobile Satellite Service (Globalstar) feeder uplinks is not exceeded. To help provide guidelines for these limits, interference models have been created with the commercial software Visualyse Professional. In this presentation, simulation results were shown for the aggregate interference power at low earth orbit from AeroMACS transmitters at each of up to 757 airports in the United States, Canada, Mexico, and the surrounding area. Both omni-directional and sectoral antenna configurations were modeled. Effects of antenna height, beamwidth, and tilt were presented.

  7. Radiative properties of the background aerosol: absorption component of extinction.

    PubMed

    Clarke, A D; Charlson, R J

    1985-07-19

    The light-scattering and light-absorption coefficients of the global background aerosol define its single-scatter albedo. Continuous, simultaneous measurements of these optical coefficients were made on a daily basis for the remote marine mid-troposphere; such measurements are essential for assessment of the effects of aerosol on atmospheric radiative transfer. Measurements of light-absorption coefficients made at the Mauna Loa Observatory in Hawaii were higher than expected, and the single-scatter albedo was lower than the value often used in radiative transfer models. Soot appears to be the most likely primary absorber, and hemispheric dispersal of this combustion-derived material is suggested.

  8. MAC/GMC 4.0 User's Manual: Keywords Manual. Volume 2

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2002-01-01

    This document is the second volume in the three volume set of User's Manuals for the Micromechanics Analysis Code with Generalized Method of Cells Version 4.0 (MAC/GMC 4.0). Volume 1 is the Theory Manual, this document is the Keywords Manual, and Volume 3 is the Example Problem Manual. MAC/GMC 4.0 is a composite material and laminate analysis software program developed at the NASA Glenn Research Center. It is based on the generalized method of cells (GMC) micromechanics theory, which provides access to the local stress and strain fields in the composite material. This access grants GMC the ability to accommodate arbitrary local models for inelastic material behavior and various types of damage and failure analysis. MAC/GMC 4.0 has been built around GMC to provide the theory with a user-friendly framework, along with a library of local inelastic, damage, and failure models. Further, applications of simulated thermo-mechanical loading, generation of output results, and selection of architectures to represent the composite material have been automated in MAC/GMC 4.0. Finally, classical lamination theory has been implemented within MAC/GMC 4.0 wherein GMC is used to model the composite material response of each ply. Consequently, the full range of GMC composite material capabilities is available for analysis of arbitrary laminate configurations as well. This volume describes the basic information required to use the MAC/GMC 4.0 software, including a 'Getting Started' section, and an in-depth description of each of the 22 keywords used in the input file to control the execution of the code.

  9. MAC/GMC 4.0 User's Manual: Example Problem Manual. Volume 3

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2002-01-01

    This document is the third volume in the three volume set of User's Manuals for the Micromechanics Analysis Code with Generalized Method of Cells Version 4.0 (MAC/GMC 4.0). Volume 1 is the Theory Manual, Volume 2 is the Keywords Manual, and this document is the Example Problems Manual. MAC/GMC 4.0 is a composite material and laminate analysis software program developed at the NASA Glenn Research Center. It is based on the generalized method of cells (GMC) micromechanics theory, which provides access to the local stress and strain fields in the composite material. This access grants GMC the ability to accommodate arbitrary local models for inelastic material behavior and various types of damage and failure analysis. MAC/GMC 4.0 has been built around GMC to provide the theory with a user-friendly framework, along with a library of local inelastic, damage, and failure models. Further, application of simulated thermo-mechanical loading, generation of output results, and selection of architectures to represent the composite material, have been automated in MAC/GMC 4.0. Finally, classical lamination theory has been implemented within MAC/GMC 4.0 wherein GMC is used to model the composite material response of each ply. Consequently, the full range of GMC composite material capabilities is available for analysis of arbitrary laminate configurations as well. This volume provides in-depth descriptions of 43 example problems, which were specially designed to highlight many of the most important capabilities of the code. The actual input files associated with each example problem are distributed with the MAC/GMC 4.0 software; thus providing the user with a convenient starting point for their own specialized problems of interest.

  10. Sound absorption by clamped poroelastic plates.

    PubMed

    Aygun, H; Attenborough, K

    2008-09-01

    Measurements and predictions have been made of the absorption coefficient and the surface acoustic impedance of poroelastic plates clamped in a large impedance tube and separated from the rigid termination by an air gap. The measured and predicted absorption coefficient and surface impedance spectra exhibit low frequency peaks. The peak frequencies observed in the absorption coefficient are close to those predicted and measured in the deflection spectra of the clamped poroelastic plates. The influences of the rigidity of the clamping conditions and the width of the air gap have been investigated. Both influences are found to be important. Increasing the rigidity of clamping reduces the low frequency absorption peaks compared with those measured for simply supported plates or plates in an intermediate clamping condition. Results for a closed cell foam plate and for two open cell foam plates made from recycled materials are presented. For identical clamping conditions and width of air gap, the results for the different materials differ as a consequence mainly of their different elasticity, thickness, and cell structure.

  11. Cloning and immunoreactivity of the 5-HT1Mac and 5-HT2Mac receptors in the central nervous system of the freshwater prawn Macrobrachium rosenbergii

    PubMed Central

    Vázquez-Acevedo, Nietzell; Reyes-Colón, Dalynés; Ruíz-Rodríguez, Eduardo A.; Rivera, Nilsa M.; Rosenthal, Joshua; Kohn, Andrea B.; Moroz, Leonid L.; Sosa, María A.

    2009-01-01

    Biogenic amines are implicated in several mental disorders, many of which involve social interactions. Simple model systems, such as crustaceans, are often more amenable than vertebrates for studying mechanisms underlying behaviors. Although various cellular responses of biogenic amines have been characterized in crustaceans, the mechanisms linking these molecules to behavior remain largely unknown. Observed effects of serotonin receptor agonists and antagonists in abdomen posture, escape responses, and fighting have led to the suggestion that biogenic amine receptors may play a role in modulating interactive behaviors. As a first step in understanding this potential role of such receptors, we have cloned and fully sequenced two serotonin receptors, 5-HT1Mac and 5-HT2Mac, from the CNS of the freshwater prawn Macrobrachium rosenbergii, and have mapped their CNS immunohistochemical distribution. 5-HT1Mac was found primarily on the membranes of subsets of cells in all CNS ganglia, in fibers that traverse all CNS regions, and in the cytoplasm of a small number of cells in the brain, circum- and subesophageal ganglia (SEG), most of which also appear to contain dopamine. The pattern of 5-HT2Mac immunoreactivity was found to differ significantly, being found mostly in the central neuropil area of all ganglia, in glomeruli of the brain’s olfactory lobes, and in the cytoplasm of a small number of neurons in the SEG, thoracic and some abdominal ganglia. The observed differences in terms of localization, distribution within cells, and intensity of immunoreactive staining throughout the prawn’s CNS suggest that these receptors are likely to play different roles. PMID:19184976

  12. Fundamentally different roles for LFA-1, Mac-1 and alpha4-integrin in neutrophil chemotaxis.

    PubMed

    Heit, Bryan; Colarusso, Pina; Kubes, Paul

    2005-11-15

    Although the LFA-1, Mac-1 and alpha(4) integrins are required for chemotaxis, it is unknown how they are regulated or what specific role they play. Previously we demonstrated that fMLP and IL-8 induce chemotaxis via the p38 MAPK and phosphoinositide 3-kinase (PI3K) pathways, respectively. Here we show that these chemoattractants also activate and use Mac-1 and LFA-1 in a differential manner during chemotaxis. Using integrin-specific substrata, we demonstrate that cell movement in response to IL-8 is mediated by Mac-1, whereas LFA-1 is required for directional migration. By contrast, chemotaxis to fMLP requires Mac-1 for cell movement, whereas LFA-1 and alpha(4)-integrin are required for directional migration. On serum protein, which contains ligands for LFA-1, Mac-1 and alpha(4)-integrin, chemotaxis to fMLP is dependent on Mac-1, whereas chemotaxis to IL-8 is dependent on LFA-1. These results suggest that Mac-1 is the dominant integrin involved in chemotaxis to fMLP, and LFA-1 is the dominant integrin involved in chemotaxis to IL-8. Consistent with these observations, higher quantities of high-affinity Mac-1 are found on cells chemotaxing to fMLP then on cells chemotaxing to IL-8. Moreover, a much larger quantity of clustered LFA-1 was found on cells migrating to IL-8 compared to cells moving towards fMLP. When cells are presented with competing gradients of fMLP and IL-8, they preferentially migrate towards fMLP and activate/utilize integrins in a manner identical to fMLP alone. Under the same conditions, p38 MAPK inhibition abolishes the preferential migration to fMLP; instead, the cells migrate preferentially towards IL-8. The activation and utilization of integrins under these conditions are consistent with patterns observed with IL-8 alone. Together, these data suggest that fMLP and IL-8 differentially activate integrins for use during chemotaxis, that p38 MAPK is a major mediator in the activation and utilization of integrins, and selective integrin

  13. Relationship of DUI recidivism to moral reasoning, sensation seeking, and MacAndrew alcoholism scores.

    PubMed

    Little, G L; Robinson, K D

    1989-12-01

    115 convicted male DUI offenders were treated with Moral Reconation Therapy during their incarceration. Postrelease recidivism status (arrests) was correlated with the pretest, posttest, and change scores on the MacAndrew Alcoholism Scale, Sensation Seeking Scale, Life-purpose scores, and Moral Reasoning scores. Analysis showed that recidivism correlated positively and significantly with the pretest scores on the MacAndrew scale and approached significance with both pre- and posttest scores on the Sensation Seeking Scale. Recidivism status correlated negatively and significantly with scores on the highest levels of moral reasoning (Scale 6 pretest and posttest and Principled Reasoning pretest).

  14. POD/MAC-Based Modal Basis Selection for a Reduced Order Nonlinear Response Analysis

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Przekop, Adam

    2007-01-01

    A feasibility study was conducted to explore the applicability of a POD/MAC basis selection technique to a nonlinear structural response analysis. For the case studied the application of the POD/MAC technique resulted in a substantial improvement of the reduced order simulation when compared to a classic approach utilizing only low frequency modes present in the excitation bandwidth. Further studies are aimed to expand application of the presented technique to more complex structures including non-planar and two-dimensional configurations. For non-planar structures the separation of different displacement components may not be necessary or desirable.

  15. Additive contribution of nitrous oxide to halothane MAC in infants and children.

    PubMed

    Murray, D J; Mehta, M P; Forbes, R B; Dull, D L

    1990-08-01

    Fifty-one infants and small children (14.7 +/- 7.2 mo) were studied to determine the MAC of halothane in O2 (n = 11) and in the presence of three different nitrous oxide (N2O) concentrations (25% [n = 13], 50% [n = 13], and 75% [n = 14]). In the three N2O groups, after randomly assigning patients to an N2O group, anesthesia was induced with halothane and N2O using a pediatric circle system. After endotracheal intubation, halothane and N2O end-expired concentrations were adjusted to predetermined concentrations. The initial halothane concentrations in each group were based on the assumption that each percent N2O reduced halothane concentrations by 0.01 vol % (assumed halothane MAC = 1.0 vol %). Based on the response of the preceding subject in each group, halothane concentrations were increased or decreased depending on whether the response was to move or not to move, respectively, in response to the surgical incision. The mean duration of constant end-tidal concentrations before skin incision was 10 min. End-tidal gases were sampled and measured from a separate distal sampling port of an endotracheal tube during controlled ventilation (Perkin-Elmer Mass Spectrometer). The MAC value for halothane in O2 was 0.94 +/- 0.08 vol % (mean +/- SD). The MAC values of halothane in the presence of 25%, 50%, and 75% N2O were 0.78 +/- 0.12 vol %, 0.44 +/- 0.10 vol %, and 0.29 +/- 0.06 vol %, respectively. All concentrations of N2O significantly reduced the MAC of halothane. A regression analysis through all four data points yielded a linear relationship (r2 = 0.87) with a predicted MAC for N2O of 105 vol %. Unlike halothane and isoflurane, the predicted MAC of N2O in infants and children is similar to that reported by others in adults. Similar to the results of clinical studies in adults, the contribution of N2O to halothane MAC in children is additive.

  16. Functional constraints on phenomenological coefficients

    NASA Astrophysics Data System (ADS)

    Klika, Václav; Pavelka, Michal; Benziger, Jay B.

    2017-02-01

    Thermodynamic fluxes (diffusion fluxes, heat flux, etc.) are often proportional to thermodynamic forces (gradients of chemical potentials, temperature, etc.) via the matrix of phenomenological coefficients. Onsager's relations imply that the matrix is symmetric, which reduces the number of unknown coefficients is reduced. In this article we demonstrate that for a class of nonequilibrium thermodynamic models in addition to Onsager's relations the phenomenological coefficients must share the same functional dependence on the local thermodynamic state variables. Thermodynamic models and experimental data should be validated through consistency with the functional constraint. We present examples of coupled heat and mass transport (thermodiffusion) and coupled charge and mass transport (electro-osmotic drag). Additionally, these newly identified constraints further reduce the number of experiments needed to describe the phenomenological coefficient.

  17. Ultraviolet (250-550  nm) absorption spectrum of pure water.

    PubMed

    Mason, John D; Cone, Michael T; Fry, Edward S

    2016-09-01

    Data for the spectral light absorption of pure water from 250 to 550 nm have been obtained using an integrating cavity made from a newly developed diffuse reflector with a very high UV reflectivity. The data provide the first scattering-independent measurements of absorption coefficients in the spectral gap between well-established literature values for the absorption coefficients in the visible (>400  nm) and UV (<200  nm). A minimum in the absorption coefficient has been observed in the UV at 344 nm; the value is 0.000811±0.000227  m-1.

  18. Wrong Signs in Regression Coefficients

    NASA Technical Reports Server (NTRS)

    McGee, Holly

    1999-01-01

    When using parametric cost estimation, it is important to note the possibility of the regression coefficients having the wrong sign. A wrong sign is defined as a sign on the regression coefficient opposite to the researcher's intuition and experience. Some possible causes for the wrong sign discussed in this paper are a small range of x's, leverage points, missing variables, multicollinearity, and computational error. Additionally, techniques for determining the cause of the wrong sign are given.

  19. 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

    to carbonyl- and nitro- functional groups on conjugated and aromatic organic structures (e.g. PAH, and terpene derived products). Using 12-hour fine (0.1-1.0 micron) aerosol samples collected in the field on quartz filters, uv/vis and infrared spectra were obtained in the laboratory using integrating spheres and diffuse reflectance spectroscopy, respectively. An inter-comparison of the "real-time" measurements made by the photo-acoustic, aethalometer and MAAP techniques have been described. In addition, the in situ aethalometer (seven-channel) results are compared with continuous integrating sphere uv-visible spectra to examine the angstrom absorption coefficient variance. These results will be briefly overviewed and the specific posters detailing these results will be highlighted highlighted. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City under the support of the Atmospheric Science Program. "This researchwas supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-07ER64329.

  20. Absorption of 9.6-micron CO2 laser radiation by CO2 at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Robinson, A. M.

    1983-03-01

    Transitions in CO2 gas induced by the absorption of 9.6 micron laser radiation at higher temperatures were examined. Several lines of the 9.6 micron 0011-0012 transition at temperatures between 296-625 K were studied, and the absorption coefficient was determined as a function of temperature. Additional trials were run to define the relative optical broadening coefficients due to He and N2 for the R16-R22 and P16-P22 transitions. The values obtained for the coefficients and the percentage contribution to calculated absorption coefficient at 620 K are provided.

  1. Comprehensive analysis of the optical Kerr coefficient of graphene

    SciTech Connect

    Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo

    2016-08-25

    We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition, self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.

  2. Comprehensive analysis of the optical Kerr coefficient of graphene

    DOE PAGES

    Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo

    2016-08-25

    We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition,more » self-coupling, and quadratic ac Stark effect. As a result, we present a comparison of our theory with recent experimental and theoretical results.« less

  3. Comprehensive analysis of the optical Kerr coefficient of graphene

    NASA Astrophysics Data System (ADS)

    Soh, Daniel B. S.; Hamerly, Ryan; Mabuchi, Hideo

    2016-08-01

    We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the S -matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-Kronig relation. In this formalism, the source of Kerr nonlinearity is the interplay of optical fields that cooperatively drive the transition from valence to conduction band. This formalism makes it possible to identify and compute the rates of distinct nonlinear processes that contribute to the Kerr nonlinear refractive index coefficient. The four identified mechanisms are two-photon absorption, Raman transition, self-coupling, and quadratic ac Stark effect. We also present a comparison of our theory with recent experimental and theoretical results.

  4. Experimental determination of terahertz atmospheric absorption parameters

    NASA Astrophysics Data System (ADS)

    Slocum, David M.; Goyette, Thomas M.; Giles, Robert H.; Nixon, William E.

    2015-05-01

    The terahertz frequency regime is often used as the `chemical fingerprint' region of the electromagnetic spectrum since many molecules exhibit a dense selection of rotational and vibrational transitions. Water is a major component of the atmosphere and since it has a large dipole moment the propagation of terahertz radiation will be dominated by atmospheric effects. This study will present the results of high-­-resolution broadband measurements of the terahertz atmospheric absorption and detail the technique for directly measuring the pressure broadening coefficients, absolute absorption coefficients, line positions, and continuum effects. Differences between these measured parameters and those tabulated in HITRAN will be discussed. Once the water vapor absorption was characterized, the same technique was used to measure the line parameters for methanol, a trace gas of interest within Earth's atmosphere. Methanol has a dense absorption spectrum in the terahertz frequency region and is an important molecule in fields such as environmental monitoring, security, and astrophysics. The data obtained in the present study will be of immediate use for the remote sensing community, as it is uncommon to measure this many independent parameters as well as to measure the absolute absorption of the transitions. Current models rely on tabulated databases of calculated values for the line parameters measured in this study. Differences between the measured data and those in the databases will be highlighted and discussed.

  5. Anomalous absorption of laser light on ion acoustic fluctuations

    NASA Astrophysics Data System (ADS)

    Rozmus, Wojciech; Bychenkov, Valery Yu.

    2016-10-01

    Theory of laser light absorption due to ion acoustic turbulence (IAT) is discussed in high Z plasmas where ion acoustic waves are weakly damped. Our theory applies to the whole density range from underdense to critical density plasmas. It includes an absorption rate for the resonance anomalous absorption due to linear conversion of electromagnetic waves into electron plasma oscillations by the IAT near the critical density in addition to the absorption coefficient due to enhanced effective electron collisionality. IAT is driven by large electron heat flux through the return current instability. Stationary spectra of IAT are given by weak plasma turbulence theory and applied in description of the anomalous absorption in the inertial confinement fusion plasmas at the gold walls of a hohlraum. This absorption is anisotropic in nature due to IAT angular anisotropy and differs for p- and s-polarization of the laser radiation. Possible experiments which could identify the resonance anomalous absorption in a laser heated plasma are discussed.

  6. An Application of MacLaury's Vantage Theory to Abstract Categories: Identity and the Process of Categorisation

    ERIC Educational Resources Information Center

    Fabiszak, Malgorzata

    2010-01-01

    This paper is an application of Robert E. MacLaury's Vantage Theory (VT) to the analysis of real life spoken discourse. It utilizes Dennis R. Preston's (1994) modification of MacLaury's VT. It elucidates how cognitive processes of coordinate selection and combination contribute to the on-line construction of category membership in the abstract…

  7. 33 CFR 334.635 - Hillsborough Bay and waters contiguous to MacDill Air Force Base, Fla.; restricted area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... contiguous to MacDill Air Force Base, Fla.; restricted area. 334.635 Section 334.635 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.635 Hillsborough Bay and waters contiguous to MacDill Air Force Base, Fla.; restricted...

  8. 42 CFR 405.1062 - Applicability of local coverage determinations and other policies not binding on the ALJ and MAC.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... MAC are not bound by LCDs, LMRPs, or CMS program guidance, such as program memoranda and manual... MAC may not set aside or review the validity of an LMRP or LCD for purposes of a claim appeal. An ALJ or the DAB may review or set aside an LCD (or any part of an LMRP that constitutes an LCD)...

  9. 42 CFR 405.1062 - Applicability of local coverage determinations and other policies not binding on the ALJ and MAC.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MAC are not bound by LCDs, LMRPs, or CMS program guidance, such as program memoranda and manual... MAC may not set aside or review the validity of an LMRP or LCD for purposes of a claim appeal. An ALJ or the DAB may review or set aside an LCD (or any part of an LMRP that constitutes an LCD)...

  10. Equivalence of Forms K and L of the Gates-MacGinitie Reading Tests with Fifth-Grade Students.

    ERIC Educational Resources Information Center

    Johns, Jerry L.; VanLeirsburg, Peggy

    A study answered the question: are there significant differences in scores for two forms of the Gates-MacGinitie Reading Tests, Third Edition? Subjects, 23 fifth graders, were given Forms K and L, Level 5/6, of the Gates-MacGinitie Reading Test. The tests were administered by the regular classroom teacher in two testing sessions. Students were…

  11. Education for Personal Life: John MacMurray on Why Learning to Be Human Requires Emotional Discipline

    ERIC Educational Resources Information Center

    MacAllister, James

    2014-01-01

    In this article I discuss the philosophy of John MacMurray, and in particular, his little-examined writings on discipline and emotion education. It is argued that discipline is a vital element in the emotion education MacMurray thought central to learning to be human, because for him it takes concerted effort to overcome the human tendency toward…

  12. Changing the Shape of American Radio Drama: Innovation and Representation in Archibald MacLeish's "The Fall of the City."

    ERIC Educational Resources Information Center

    Novak, Glenn D.

    The (CBS Radio) Columbia Workshop, formed in 1936, encouraged the writing and production of creative, non-traditional radio drama such as Archibald MacLeish's verse play "The Fall of the City," which aired on April 11, 1937. MacLeish considered radio the ideal medium for poetry because it offers only aural stimuli without competition…

  13. Subbarrier absorption in a stationary superlattice

    NASA Technical Reports Server (NTRS)

    Arutyunyan, G. M.; Nerkararyan, K. V.

    1984-01-01

    The calculation of the interband absorption coefficient was carried out in the classical case, when the frequency of light was assumed to bind two miniband subbarrier states of different bands. The influence of two dimensional Mott excitons on this absorption was studied and a comparison was made with the experiment. All of these considerations were done taking into account the photon wave vector (the phase spatial heterogeneity). The basic traits of the energy spectra of superlattice semiconductors, their kinetic and optical properties, and possible means of electromagnetic wave intensification were examined. By the density matrix method, a theory of electrical and electromagnetic properties of superlattices was suggested.

  14. Monitoring of MOCVD reactants by UV absorption

    SciTech Connect

    Baucom, K.C.; Killeen, K.P.; Moffat, H.K.

    1995-07-01

    In this paper, we describe how UV absorption measurements can be used to measure the flow rates of metal organic chemical vapor deposition (MOCVD) reactants. This method utilizes the calculation of UV extinction coefficients by measuring the total pressure and absorbance in the neat reactant system. The development of this quantitative reactant flow rate monitor allows for the direct measurement of the efficiency of a reactant bubbler. We demonstrate bubbler efficiency results for TMGa, and then explain some discrepancies found in the TMAl system due to the monomer to dimer equilibrium. Also, the UV absorption spectra of metal organic and hydride MOCVD reactants over the wavelength range 185 to 400 nm are reported.

  15. Atmospheric absorption cell characterization

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The measurement capability of the Avionics Laboratory IR Facility was used to evaluate an absorption cell that will be used to simulate atmospheric absorption over horizontal paths of 1 - 10 km in length. Band models were used to characterize the transmittance of carbon dioxide (CO2), nitrogen (N2), and nitrous oxide (N2O) in the cell. The measured transmittance was compared to the calculated values. Nitrous oxide is important in the 4 - 4.5 micron range in shaping the weak line absorption of carbon dioxide. The absorption cell is adequate for simulating atmospheric absorption over these paths.

  16. On the errors in measuring the particle density by the light absorption method

    SciTech Connect

    Ochkin, V. N.

    2015-04-15

    The accuracy of absorption measurements of the density of particles in a given quantum state as a function of the light absorption coefficient is analyzed. Errors caused by the finite accuracy in measuring the intensity of the light passing through a medium in the presence of different types of noise in the recorded signal are considered. Optimal values of the absorption coefficient and the factors capable of multiplying errors when deviating from these values are determined.

  17. CLASH-VLT: Substructure in the galaxy cluster MACS J1206.2-0847 from kinematics of galaxy populations

    NASA Astrophysics Data System (ADS)

    Girardi, M.; Mercurio, A.; Balestra, I.; Nonino, M.; Biviano, A.; Grillo, C.; Rosati, P.; Annunziatella, M.; Demarco, R.; Fritz, A.; Gobat, R.; Lemze, D.; Presotto, V.; Scodeggio, M.; Tozzi, P.; Bartosch Caminha, G.; Brescia, M.; Coe, D.; Kelson, D.; Koekemoer, A.; Lombardi, M.; Medezinski, E.; Postman, M.; Sartoris, B.; Umetsu, K.; Zitrin, A.; Boschin, W.; Czoske, O.; De Lucia, G.; Kuchner, U.; Maier, C.; Meneghetti, M.; Monaco, P.; Monna, A.; Munari, E.; Seitz, S.; Verdugo, M.; Ziegler, B.

    2015-07-01

    Aims: In the effort to understand the link between the structure of galaxy clusters and their galaxy populations, we focus on MACS J1206.2-0847 at z ~ 0.44 and probe its substructure in the projected phase space through the spectrophotometric properties of a large number of galaxies from the CLASH-VLT survey. Methods: Our analysis is mainly based on an extensive spectroscopic dataset of 445 member galaxies, mostly acquired with VIMOS at VLT as part of our ESO Large Programme, sampling the cluster out to a radius ~2R200 (4 h70-1 Mpc). We classify 412 galaxies as passive, with strong Hδ absorption (red and blue galaxies), and with emission lines from weak to very strong. A number of tests for substructure detection are applied to analyze the galaxy distribution in the velocity space, in 2D space, and in 3D projected phase-space. Results: Studied in its entirety, the cluster appears as a large-scale relaxed system with a few secondary, minor overdensities in 2D distribution. We detect no velocity gradients or evidence of deviations in local mean velocities. The main feature is the WNW-ESE elongation. The analysis of galaxy populations per spectral class highlights a more complex scenario. The passive galaxies and red strong Hδ galaxies trace the cluster center and the WNW-ESE elongated structure. The red strong Hδ galaxies also mark a secondary, dense peak ~2 h70-1 Mpcat ESE. The emission line galaxies cluster in several loose structures, mostly outside R200. Two of these structures are also detected through our 3D analysis. The observational scenario agrees with MACS J1206.2-0847 having WNW-ESE as the direction of the main cluster accretion, traced by passive galaxies and red strong Hδ galaxies. The red strong Hδ galaxies, interpreted as poststarburst galaxies, date a likely important event 1-2 Gyr before the epoch of observation. The emission line galaxies trace a secondary, ongoing infall where groups are accreted along several directions. Based in large part

  18. Sound absorption of metallic sound absorbers fabricated via the selective laser melting process

    NASA Astrophysics Data System (ADS)

    Cheng, Li-Wei; Cheng, Chung-Wei; Chung, Kuo-Chun; Kam, Tai-Yan

    2017-01-01

    The sound absorption capability of metallic sound absorbers fabricated using the additive manufacturing (selective laser melting) method is investigated via both the experimental and theoretical approaches. The metallic sound absorption structures composed of periodic cubic cells were made of laser-melted Ti6Al4 V powder. The acoustic impedance equations with different frequency-independent and frequency-dependent end corrections factors are employed to calculate the theoretical sound absorption coefficients of the metallic sound absorption structures. The calculated sound absorption coefficients are in close agreement with the experimental results for the frequencies ranging from 2 to 13 kHz.

  19. Intracavity Dye-Laser Absorption Spectroscopy (IDLAS) for application to planetary molecules

    NASA Technical Reports Server (NTRS)

    Lang, Todd M.; Allen, John E., Jr.

    1990-01-01

    Time-resolved, quasi-continuous wave, intracavity dye-laser absorption spectroscopy is applied to the investigation of absolute absorption coefficients for vibrational-rotational overtone bands of water at visible wavelengths. Emphasis is placed on critical factors affecting detection sensitivity and data analysis. Typical generation-time dependent absorption spectra are given.

  20. Parametric distortion of the optical absorption edge of a magnetic semiconductor by a strong laser field

    SciTech Connect

    Nunes, O.A.C.

    1985-09-15

    The influence of a strong laser field on the optical absorption edge of a direct-gap magnetic semiconductor is considered. It is shown that as the strong laser intensity increases the absorption coefficient is modified so as to give rise to an absorption tail below the free-field forbidden gap. An application is made for the case of the EuO.

  1. Dependence of AeroMACS Interference on Airport Radiation Pattern Characteristics

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    2012-01-01

    AeroMACS (Aeronautical Mobile Airport Communications System), which is based upon the IEEE 802.16e mobile wireless standard, is expected to be implemented in the 5091 to 5150 MHz frequency band. As this band is also occupied by Mobile Satellite Service (MSS) feeder uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference are under analysis in order to enable the definition of standards that assure that such interference will be avoided. In this study, the cumulative interference power distribution at low earth orbit from AeroMACS transmitters at the 497 major airports in the contiguous United States was simulated with the Visualyse Professional software. The dependence of the interference power on the number of antenna beams per airport, gain patterns, and beam direction orientations was simulated. As a function of these parameters, the simulation results are presented in terms of the limitations on transmitter power required to maintain the cumulative interference power under the established threshold.

  2. Using a Networked Mac Lab To Facilitate Learning in Art, Foreign Languages, and English.

    ERIC Educational Resources Information Center

    Brutchin, Patricia; And Others

    These presentations examine the use of a new Macintosh Lab in Commercial Art Technology, Spanish, and English Composition classes at Clark State Community College. The first paper describes the Commercial Art Technology program at the college, highlighting the use of the Mac Lab installed in September 1993 and discussing the Electronic Publishing,…

  3. The Mac Internet Tour Guide: Cruising the Internet the Easy Way. [First Edition.

    ERIC Educational Resources Information Center

    Fraase, Michael

    Published exclusively for MacIntosh computer users, this guide provides an overview of Internet resources for new and experienced users. E-mail, file transfer, and decompression software used to access the resources are included on a 800k, 3.5 inch disk. The following chapters are included: (1) "What Is the Internet" covers finding your…

  4. The Big Mac and Teaching about Japan. Footnotes. Volume 8, Number 5

    ERIC Educational Resources Information Center

    Ellington, Lucien

    2003-01-01

    The Big Mac can be effective tool in helping students achieve a better understanding of Japan. It can defeat Orientalist stereotypes about the Japanese--and also challenge young people who might have oversimplified notions of what exactly occurs when U.S. fast food chains take root in another culture. Many deride McDonald's as a villain…

  5. Berkeley Lab Scientist Named MacArthur ''Genius'' Fellow for Audio Preservation Research

    SciTech Connect

    Haber, Carl

    2013-09-24

    Audio Preservationist Carl Haber was named a MacArthur Fellow in 2013. The Fellowship is a $625,000, no-strings-attached grant for individuals who have shown exceptional creativity in their work and the promise to do more. Learn more at http://www.macfound.org/fellows.

  6. Analysis and convergence of the MAC scheme. Part 1: The linear problem

    NASA Technical Reports Server (NTRS)

    Nicolaides, R. A.

    1991-01-01

    The MAC discretization of fluid flow is analyzed for the stationary Stokes equations. It is proved that the discrete approximations do in fact converge to the exact solutions of the flow equations. Estimates using mesh dependent norms analogous to the standard H(sup 1) and L(sup 2) norms are given for the velocity and pressure, respectively.

  7. Detecting DIF in Polytomous Items Using MACS, IRT and Ordinal Logistic Regression

    ERIC Educational Resources Information Center

    Elosua, Paula; Wells, Craig

    2013-01-01

    The purpose of the present study was to compare the Type I error rate and power of two model-based procedures, the mean and covariance structure model (MACS) and the item response theory (IRT), and an observed-score based procedure, ordinal logistic regression, for detecting differential item functioning (DIF) in polytomous items. A simulation…

  8. A Survey of MAC Protocols for Cognitive Radio Body Area Networks

    PubMed Central

    Bhandari, Sabin; Moh, Sangman

    2015-01-01

    The advancement in electronics, wireless communications and integrated circuits has enabled the development of small low-power sensors and actuators that can be placed on, in or around the human body. A wireless body area network (WBAN) can be effectively used to deliver the sensory data to a central server, where it can be monitored, stored and analyzed. For more than a decade, cognitive radio (CR) technology has been widely adopted in wireless networks, as it utilizes the available spectra of licensed, as well as unlicensed bands. A cognitive radio body area network (CRBAN) is a CR-enabled WBAN. Unlike other wireless networks, CRBANs have specific requirements, such as being able to automatically sense their environments and to utilize unused, licensed spectra without interfering with licensed users, but existing protocols cannot fulfill them. In particular, the medium access control (MAC) layer plays a key role in cognitive radio functions, such as channel sensing, resource allocation, spectrum mobility and spectrum sharing. To address various application-specific requirements in CRBANs, several MAC protocols have been proposed in the literature. In this paper, we survey MAC protocols for CRBANs. We then compare the different MAC protocols with one another and discuss challenging open issues in the relevant research. PMID:25903551

  9. General MacArthur’s Strategic Success During the Early Months of the Korean War

    DTIC Science & Technology

    2012-05-17

    Almond , FECOM’s Chief of Staff, recommended to General MacArthur to send a US infantry task force to Korea with the purpose to delay the North...elements of combat power. 156 MG Almond did not organize the GHQ as a joint headquarters to exploit the opportunities such as the North Korean long

  10. Application of Multihop Relay for Performance Enhancement of AeroMACS Networks

    NASA Technical Reports Server (NTRS)

    Kamali, Behnam; Wilson, Jeffrey D.; Kerczewski, Robert J.

    2012-01-01

    A new transmission technology, based on IEEE 802.16-2009 (WiMAX), is currently being developed for airport surface communications. A C-band spectrum allocation at 5091 to 5150 MHz has been created by International Telecommunications Union (ITU) to carry this application. The proposed technology, known as AeroMACS, will be used to support fixed and mobile ground to ground applications and services. This article proposes and demonstrates that IEEE 802.16j-amendment-based WiMAX is most feasible for AeroMACS applications. This amendment introduces multihop relay as an optional deployment that may be used to provide additional coverage and/or enhance the capacity of the network. Particular airport surface radio coverage situations for which IEEE 802.16-2009-WiMAX provides resolutions that are inefficient, costly, or excessively power consuming are discussed. In all these cases, it is argued that 16j technology offers a much better alternative. A major concern about deployment of AeroMACS is interference to co-allocated applications such as the Mobile Satellite Service (MSS) feeder link. Our initial simulation results suggest that no additional interference to MSS feeder link is caused by deployment of IEEE 802.16j-based AeroMACS.

  11. Young Galaxy Candidates in the Hubble Frontier Fields. IV. MACS J1149.5+2223

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Zitrin, Adi; Infante, Leopoldo; Laporte, Nicolas; Huang, Xingxing; Moustakas, John; Ford, Holland C.; Shu, Xinwen; Wang, Junxian; Diego, Jose M.; Bauer, Franz E.; Troncoso Iribarren, Paulina; Broadhurst, Tom; Molino, Alberto

    2017-02-01

    We search for high-redshift dropout galaxies behind the Hubble Frontier Fields (HFF) galaxy cluster MACS J1149.5+2223, a powerful cosmic lens that has revealed a number of unique objects in its field. Using the deep images from the Hubble and Spitzer space telescopes, we find 11 galaxies at z > 7 in the MACS J1149.5+2223 cluster field, and 11 in its parallel field. The high-redshift nature of the bright z ≃ 9.6 galaxy MACS1149-JD, previously reported by Zheng et al., is further supported by non-detection in the extremely deep optical images from the HFF campaign. With the new photometry, the best photometric redshift solution for MACS1149-JD reduces slightly to z = 9.44 ± 0.12. The young galaxy has an estimated stellar mass of (7+/- 2)× {10}8 {M}ȯ , and was formed at z={13.2}-1.6+1.9 when the universe was ≈300 Myr old. Data available for the first four HFF clusters have already enabled us to find faint galaxies to an intrinsic magnitude of {M}{UV}≃ -15.5, approximately a factor of 10 deeper than the parallel fields.

  12. Assessing Early Communicative Ability: A Cross-Reporter Cumulative Score for the MacArthur CDI

    ERIC Educational Resources Information Center

    De Houwer, Annick; Bornstein, Marc H.; Leach, Diane B.

    2005-01-01

    Thirty middle- to upper middle-class monolingual Dutch speaking families consisting of at least a mother and a father completed the Infant Form "Words and Gestures" of the Dutch adaptation of the MacArthur Communicative Development Inventory for the same child at 1;1. Considerable inter- and intrafamily variation emerged in how two (or three)…

  13. 78 FR 5320 - Federal Agricultural Mortgage Corporation Funding and Fiscal Affairs; Farmer Mac Capital Planning

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-25

    ... strategies, and (iii) provide FCA with notification of Farmer Mac's proposed capital distributions before... cushion to absorb unexpected losses and improve an institution's long-term resilience. The recent global...\\ Bank for International Settlements, Basel Committee on Banking Supervision, Basel III, A...

  14. Final Environmental Assessment for Aerial Spraying for Invasive Species Control MacDill AFB, Florida

    DTIC Science & Technology

    2007-09-01

    golf courses are sources of known contamination. 3.5 FLOODPLAINS MacDill AFB’s topography is flat, with surface elevations that range from sea...contact. MSDS: Nufarm Weedar 64 BroadleafHerbicide Page 2 of7 Eye Contact: Causes corneal opacity, irreversible eye damage. Vapors and mist can cause

  15. The Westley-MacLean Model Revisited: An Extension of a Conceptual Model for Communication Research.

    ERIC Educational Resources Information Center

    Lacy, Stephen

    A revision of the Westley-MacLean model of 1957 for communication research accommodates an incorporation of some of the research areas that have blossomed during the last three decades. The revision concentrates on two aspects of the original: (1) organizational features within the advocate, communicator and audience roles; and (2) environmental…

  16. 33 CFR 165.768 - Security Zone; MacDill Air Force Base, Tampa Bay, FL.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS AREAS Specific Regulated Navigation Areas and Limited Access Areas Seventh Coast Guard District § 165.768 Security Zone; MacDill Air Force Base, Tampa Bay, FL. (a) Location. The following area is...

  17. There is no MacWilliams identity for convolutional codes. [transmission gain comparison

    NASA Technical Reports Server (NTRS)

    Shearer, J. B.; Mceliece, R. J.

    1977-01-01

    An example is provided of two convolutional codes that have the same transmission gain but whose dual codes do not. This shows that no analog of the MacWilliams identity for block codes can exist relating the transmission gains of a convolutional code and its dual.

  18. Foreign Language Authoring Systems: Judith Frommer's MacLang Spoken Here.

    ERIC Educational Resources Information Center

    Frommer, Judith

    1987-01-01

    MacLang, a user-friendly authoring system for the Macintosh computer, helps second language teachers prepare and tailor computer exercises and activities; is usable with any Roman-alphabet language, Russian, and Greek; gives students intelligent feedback; and allows students to control computer activity in order to individualize learning.…

  19. 75 FR 69154 - Land Release for Long Island MacArthur Airport

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-10

    ... proposed release from aeronautical use of approximately 17.69 acres of airport property, to allow for non-aeronautical development. The parcel is located on the northeast corner of the Long Island MacArthur Airport... sponsor's Federal obligation to use certain airport land for aeronautical use. Issued in Garden City,...

  20. Low Power and Robust PHY-MAC Solution for Medical BAN

    NASA Astrophysics Data System (ADS)

    Farserotu, John R.; Gerrits, John F. M.; Rousselot, Jérôme

    This paper provides an overview of CSEMs FM-UWB PHY-MAC proposal to IEEE802.15.6, Task Group 6, Body Area Networks. The proposed solution provides for an ultra low power, yet robust and reliable solution for low data rate medical BAN. The paper examines the key features and performance aspects of the proposal.

  1. Teaching Justice after MacIntyre: Toward a Catholic Philosophy of Moral Education

    ERIC Educational Resources Information Center

    Bergman, Roger

    2008-01-01

    How is the commitment to social justice sustained over a lifetime? This would seem to be a matter of character, and that calls attention to the Aristotelian tradition in ethics. No one provides as much insight into the challenge of the contemporary appropriation of this tradition as Alasdair MacIntyre. Although a moral philosopher rather than a…

  2. New upper bounds on the rate of a code via the Delsarte-MacWilliams inequalities

    NASA Technical Reports Server (NTRS)

    Mceliece, R. J.; Rodemich, E. R.; Rumsey, H., Jr.; Welch, L. R.

    1977-01-01

    An upper bound on the rate of a binary code as a function of minimum code distance (using a Hamming code metric) is arrived at from Delsarte-MacWilliams inequalities. The upper bound so found is asymptotically less than Levenshtein's bound, and a fortiori less than Elias' bound. Appendices review properties of Krawtchouk polynomials and Q-polynomials utilized in the rigorous proofs.

  3. Moraine Area Career System (MACS). Technology Preparation Final Report for 1992.

    ERIC Educational Resources Information Center

    Moraine Valley Community Coll., Palos Hills, IL.

    The Moraine Area Career System (MACS) Tech Prep Applied Academics Core project was undertaken to develop a written replicable model core of applied academics for selected vocational-technical programs that would emphasize Illinois goals for learning and technical content (including critical and computer literacy). A tech prep advisory council…

  4. Berkeley Lab Scientist Named MacArthur ''Genius'' Fellow for Audio Preservation Research

    ScienceCinema

    Haber, Carl

    2016-07-12

    Audio Preservationist Carl Haber was named a MacArthur Fellow in 2013. The Fellowship is a $625,000, no-strings-attached grant for individuals who have shown exceptional creativity in their work and the promise to do more. Learn more at http://www.macfound.org/fellows.

  5. CEFPI 2000 Design Portfolio: James D. MacConnell Award Winner.

    ERIC Educational Resources Information Center

    Educational Facility Planner, 2000

    2000-01-01

    Presents an architectural description of the Edmonds-Woodway High School (Washington), winner of the James D. MacConnel Award from the Council of Educational Facility Planners, International. Photos, floor plans, and project data and school statistics are included. (GR)

  6. Short-Form Versions of the Spanish MacArthur-Bates Communicative Development Inventories

    ERIC Educational Resources Information Center

    Jackson-Maldonodo, Donna; Marchman, Virginia A.; Fernald, Lia C. H.

    2013-01-01

    The Spanish-language MacArthur-Bates Communicative Development Inventories (S-CDIs) are well-established parent report tools for assessing the language development of Spanish-speaking children under 3 years. Here, we introduce the short-form versions of the S-CDIs (SFI and SFII), offered as alternatives to the long forms for screening purposes or…

  7. Environmental Assessment for Construct/Demolish Dog Kennel Facility MacDill AFB, Florida

    DTIC Science & Technology

    2003-04-01

    Re: Working Dog Kennel Correspondence 2610 Pink Flamingo Ave. Bldg. 147 Room 306 Phone: (813) 828-0459 Fax: (813) 828-2212 E-mail...of October. Thank you for your support. Jason K Jason Kirkpatrick, 6 CES/CEVN Environmental Program Manager 2610 Pink Flamingo Avenue MacDill AFB

  8. Geochemistry and petrography of the MacAlpine Hills lunar meteorites

    SciTech Connect

    Lindstrom, M.M.; McKay, D.S. ); Wentworth, S.J.; Martinez, R.R.; Mittlefehldt, D.W. ); Wang, Mingsheng; Lipschutz, M.E. )

    1991-11-01

    MacAlpine Hills 88104 and 88105 are anorthositic lunar meteorites recovered from the same area in Antarctica which are demonstrated to be paired samples of the same fall. Petrographic studies of matrix and clasts show that mAC88104/5 is a polymict breccia dominated by impact melt clasts. It contains a small amount of highland impact glass and very few regolith glass spherules. It is better classified as a fragmental breccia than a regolith breccia. The bulk composition is ferroan (mg{prime} = 63) and highly aluminous (Al{sub 2}O{sub 3} = 28%). REE and other incompatible element concentrations are very low. Compositions of anorthositic, granulitic, and impact melt breccia clasts are very similar to, but distinct from, matrix composition. MAC88104/5 is very similar in composition to the other anorthositic lunar meteorites, but each of the meteorites is distinct. The anorthositic lunar meteorites, especially MAC88104/5 and Y82192/3/86032, are very similar to North Ray Crater feldspathic fragmental breccias in composition and petrography. These fragmental lunar meteorites may have been ancient, deeply buried breccias from the megaregolith. Comparisons of chemical petrographic features and exposure histories suggest that the twelve lunar meteorites were derived from two to nine, but probably four to seven, impact onto the lunar surface. Discrepancies between the proportions of lunar meteorites and results of Apollo missions may be due to unrepresentative sampling. Lunar meteorites provide valuable new information on the nature of the lunar crust.

  9. Environmental Assessment for Perimeter Security Lighting at Fort MacArthur, California

    DTIC Science & Technology

    2007-07-01

    community of San Pedro. Soils within this association typically consist of marine sandstone, shale and breccia . Topography The community of San Pedro...typically comprised of marine sandstone, shale and breccia . Fort MacArthur is situated on Montezuma Clay Adobe which consists of excessively drained

  10. Assessing Internalizing, Externalizing, and Attention Problems in Young Children: Validation of the MacArthur HBQ

    ERIC Educational Resources Information Center

    Lemery-Chalfant, Kathryn; Schreiber, Jane E.; Schmidt, Nicole L.; Van Hulle, Carol A.; Essex, Marilyn J.; Goldsmith, H. H.

    2007-01-01

    Objective: To test the validity of the MacArthur Health and Behavior Questionnaire (HBQ) using receiver operating characteristic (ROC) analysis to determine optimal thresholds for the HBQ in predicting Diagnostic Interview Schedule for Children Version-IV (DISC-IV)diagnoses. The roles of child sex, level of impairment, and physical health in…

  11. Dependence of AeroMACS Interference on Airport Radiation Pattern Characteristics

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    2012-01-01

    AeroMACS (Aeronautical Mobile Airport Communications System), which is based upon the IEEE 802.16e mobile wireless standard, is expected to be implemented in the 5091-5150 MHz frequency band. As this band is also occupied by Mobile Satellite Service (MSS) feeder uplinks, AeroMACS must be designed to avoid interference with this incumbent service. The aspects of AeroMACS operation that present potential interference are under analysis in order to enable the definition of standards that assure that such interference will be avoided. In this study, the cumulative interference power distribution at low earth orbit from AeroMACS transmitters at the 497 major airports in the contiguous United States was simulated with the Visualyse Professional software. The dependence of the interference power on the number of antenna beams per airport, gain patterns, and beam direction orientations was simulated. As a function of these parameters, the simulation results are presented in terms of the limitations on transmitter power required to maintain the cumulative interference power under the established threshold.

  12. Testing Evolutionary Hypotheses in the Classroom with MacClade Software.

    ERIC Educational Resources Information Center

    Codella, Sylvio G.

    2002-01-01

    Introduces MacClade which is a Macintosh-based software package that uses the techniques of cladistic analysis to explore evolutionary patterns. Describes a novel and effective exercise that allows undergraduate biology majors to test a hypothesis about behavioral evolution in insects. (Contains 13 references.) (Author/YDS)

  13. Application of Multihop Relay for Performance Enhancement of AeroMACS Networks

    NASA Technical Reports Server (NTRS)

    Kamali, Behnam; Wilson, Jeffrey D.; Kerczewski, Robert J.

    2012-01-01

    A new transmission technology, based on IEEE 802.16-2009 (WiMAX), is currently being developed for airport surface communications. A C-band spectrum allocation at 5091-5150 MHz has been created by ITU to carry this application. The proposed technology, known as AeroMACS, will be used to support fixed and mobile ground to ground applications and services. This article proposes and demonstrates that IEEE 802.16j-amendment-based WiMAX is most feasible for AeroMACS applications. This amendment introduces multihop relay as an optional deployment that may be used to provide additional coverage and/or enhance the capacity of the network. Particular airport surface radio coverage situations for which IEEE 802.16-2009-WiMAX provides resolutions that are inefficient, costly, or excessively power consuming are discussed. In all these cases, it is argued that 16j technology offers a much better alternative. A major concern about deployment of AeroMACS is interference to co-allocated applications such as the Mobile Satellite Service (MSS) feeder link. Our initial simulation results suggest that no additional interference to MSS feeder link is caused by deployment of IEEE 802.16j-based AeroMACS.

  14. The Leishmania donovani histidine acid ecto-phosphatase LdMAcP: insight into its structure and function

    PubMed Central

    Papadaki, Amalia; Politou, Anastasia S.; Smirlis, Despina; Kotini, Maria P.; Kourou, Konstadina; Papamarcaki, Thomais; Boleti, Haralabia

    2015-01-01

    Acid ecto-phosphatase activity has been implicated in Leishmania donovani promastigote virulence. In the present study, we report data contributing to the molecular/structural and functional characterization of the L. donovani LdMAcP (L. donovani membrane acid phosphatase), member of the histidine acid phosphatase (HAcP) family. LdMAcP is membrane-anchored and shares high sequence identity with the major secreted L. donovani acid phosphatases (LdSAcPs). Sequence comparison of the LdMAcP orthologues in Leishmania sp. revealed strain polymorphism and species specificity for the L. donovani complex, responsible for visceral leishmaniasis (Khala azar), proposing thus a potential value of LdMAcP as an epidemiological or diagnostic tool. The extracellular orientation of the LdMAcP catalytic domain was confirmed in L. donovani promastigotes, wild-type (wt) and transgenic overexpressing a recombinant LdMAcP–mRFP1 (monomeric RFP1) chimera, as well as in transiently transfected mammalian cells expressing rLdMAcP–His. For the first time it is demonstrated in the present study that LdMAcP confers tartrate resistant acid ecto-phosphatase activity in live L. donovani promastigotes. The latter confirmed the long sought molecular identity of at least one enzyme contributing to this activity. Interestingly, the L. donovani rLdMAcP–mRFP1 promastigotes generated in this study, showed significantly higher infectivity and virulence indexes than control parasites in the infection of J774 mouse macrophages highlighting thereby a role for LdMAcP in the parasite's virulence. PMID:25695743

  15. Characterizing the Interaction Between Routing and MAC Protocols in Ad-Hoc Networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, A.; Marathe, M. V.

    2002-01-01

    We empirically study the effect of mobility on the performance of protocols designed for wireless ad-hoc networks. An important objective is to study the interaction of the Routing and MAC layer protocols under different mobility parameters. We use three basic mobility models: grid mobility model, random waypoint model, and exponential correlated random model. The performance of protocols is measured in terms of (i) latency, (ii) throughput, (iii) number of packets received, (iv) long term fairness and (v) number of control packets at the MAC and routing layer level. Three different commonly studied routing protocols are used: AODV, DSR and LAR1. Similarly three well known MAC protocols are used: MACA, 802.1 1 and CSMA. Our main contribution is simulation based experiments coupled with rigorous statistical analysis to characterize the interaction of MAC layer protocols with routing layer protocols in ad-hoc networks. From the results, we can conclude the following: e No single MAC or Routing protocol dominated the other protocols in their class. Probably more interestingly, no MAURouting protocol combination was better than other combinations over all scenarios and response variables. 0 In general, it is not meaningful to speak about a MAC or a routing protocol in isolation. Presence of interaction leads to trade-offs between the amount of control packets generated by each layer. The results raise the possibility of improving the performance of a particular MAC layer protocol by using a cleverly designed routing protocol or vice-versa. Thus in order to improve the performanceof a communication network, it is important to study the entire protocol stack as a single algorithmic construct; optimizing individual layers in the seven layer OS1 stack will not yield performance improvements beyond a point. A methodological contribution of this paper is the use of statistical methods such as analysis of variance (ANOVA), to characterize the interaction between the protocols

  16. Orthogonality of spherical harmonic coefficients

    NASA Technical Reports Server (NTRS)

    Mcleod, M. G.

    1980-01-01

    Orthogonality relations are obtained for the spherical harmonic coefficients of functions defined on the surface of a sphere. Following a brief discussion of the orthogonality of Fourier series coefficients, consideration is given to the values averaged over all orientations of the coordinate system of the spherical harmonic coefficients of a function defined on the surface of a sphere that can be expressed in terms of Legendre polynomials for the special case where the function is the sum of two delta functions located at two different points on the sphere, and for the case of an essentially arbitrary function. It is noted that the orthogonality relations derived have found applications in statistical studies of the geomagnetic field.

  17. Modification of Einstein A Coefficient in Dissipative Gas Medium

    NASA Technical Reports Server (NTRS)

    Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng

    1996-01-01

    Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.

  18. Triplet extinction coefficients of some laser dyes. II

    SciTech Connect

    Pavlopoulos, T.G.; Golich, D.J.

    1990-01-01

    We measured the triplet extinction coefficients over the laser action spectral region of DODC, DMC, Sulforhodamine B, Rhodamine 575, Coumarin 523, Coumarin 521, Coumarin 504, Coumarin 498, Coumarin 490, LD466, bis-MSB, and BBO. We employed the different lines from an argon and a krypton ion cw laser for excitation. McClure's method was again employed to measure the triplet extinction coefficients. We provide a simplified derivation of McClure's equation. The triplet extinction coefficient of Rhodamine 575 was also measured by using the depletion method and improving it by reconstructing for true triplet-triplet (T-T) absorption. The ET value obtained is in good agreement with the one obtained by McClure's method.

  19. Determination of stream reaeration coefficients by use of tracers

    USGS Publications Warehouse

    Kilpatrick, F.A.; Rathbun, R.E.; Yotsukura, Nobuhiro; Parker, G.W.; DeLong, L.L.

    1987-01-01

    Stream reaeration is the physical absorption of oxygen from the atmosphere by a flowing stream. This is the primary process by which a stream replenishes the oxygen consumed in the biodegradation of organic wastes. Prior to 1965, reaeration rate coefficients could be estimated only by indirect methods. In 1965, a direct method of measuring stream reaeration coefficients was developed in which a radioactive tracer gas was injected into a stream--the tracer gas being desorbed from the stream inversely to how oxygen would be absorbed. The technique has since been modified by substituting hydrocarbon gases for the radioactive tracer gas. The slug-injection and constant-rate injection methods of performing gas tracer desorption measurements are described. Emphasis is on the use of rhodamine WT dye as a relatively conservative tracer and propane as the nonconservative gas tracer, on planning field tests, methods of injection, sampling and analysis, and computational techniques to compute desorption and reaeration coefficients. (Author 's abstract)

  20. MacA is a second cytochrome c peroxidase of Geobacter sulfurreducens.

    PubMed

    Seidel, Julian; Hoffmann, Maren; Ellis, Katie E; Seidel, Antonia; Spatzal, Thomas; Gerhardt, Stefan; Elliott, Sean J; Einsle, Oliver

    2012-04-03

    The metal-reducing δ-proteobacterium Geobacter sulfurreducens produces a large number of c-type cytochromes, many of which have been implicated in the transfer of electrons to insoluble metal oxides. Among these, the dihemic MacA was assigned a central role. Here we have produced G. sulfurreducens MacA by recombinant expression in Escherichia coli and have solved its three-dimensional structure in three different oxidation states. Sequence comparisons group MacA into the family of diheme cytochrome c peroxidases, and the protein indeed showed hydrogen peroxide reductase activity with ABTS(-2) as an electron donor. The observed K(M) was 38.5 ± 3.7 μM H(2)O(2) and v(max) was 0.78 ± 0.03 μmol of H(2)O(2)·min(-1)·mg(-1), resulting in a turnover number k(cat) = 0.46 · s(-1). In contrast, no Fe(III) reductase activity was observed. MacA was found to display electrochemical properties similar to other bacterial diheme peroxidases, in addition to the ability to electrochemically mediate electron transfer to the soluble cytochrome PpcA. Differences in activity between CcpA and MacA can be rationalized with structural variations in one of the three loop regions, loop 2, that undergoes conformational changes during reductive activation of the enzyme. This loop is adjacent to the active site heme and forms an open loop structure rather than a more rigid helix as in CcpA. For the activation of the protein, the loop has to displace the distal ligand to the active site heme, H93, in loop 1. A H93G variant showed an unexpected formation of a helix in loop 2 and disorder in loop 1, while a M297H variant that altered the properties of the electron transfer heme abolished reductive activation.