Sample records for extra-column band broadening

  1. Understanding and diminishing the extra-column band broadening effects in supercritical fluid chromatography. (United States)

    De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken


    Supercritical fluid chromatography, where a low-viscosity mobile phase such as carbon dioxide is used, proves to be an excellent technique for fast and efficient separations, especially when sub-2μm particles are used. However, to achieve high velocities when using these small particles, and in order to stay within the flow rate range of current SFC-instruments, narrow columns (e.g. 2.1mm ID) must be used. Unfortunately, state-of-the-art instrumentation is limiting the full separation power of these narrower columns due to significant extra-column band broadening effects. The present work identifies and quantifies the different contributions to extra-column band broadening in SFC such as the influence of the sample solvent, injection volume, extra-column volumes and detector cell volume/design. When matching the sample solvent to the mobile phase in terms of elution strength and polarity (e.g. using hexane/ethanol/isopropanol 85/10/5vol%) and lowering the injection volume to 0.4μL, the plate count can be increased from 7600 to 21,300 for a low-retaining compound (k'=2.3) on a 2.1mm×150mm column (packed with 1.8μm particles). The application of a water/acetonitrile mixture as sample solvent was also investigated. It was found that when the volumetric ratio of water/acetonitrile was optimized, only a slightly lower plate count was measured compared to the hexane-based solvent when minimizing injection and extra-column volume. This confirms earlier results that water/acetonitrile can be used if water-soluble samples are considered or when a less volatile solvent is preferred. Minimizing the ID of the connection capillaries from 250 to 65μm, however, gives no further improvement in obtained efficiency for early-eluting compounds when a standard system configuration with optimized sample solvent was used. When switching to a state-of-the-art detector design with reduced (dispersion) volume (1.7-0.6μL), an increase in plate count is observed (from 11,000 to 14

  2. Effects of extra-column band spreading, liquid chromatography system operating pressure, and column temperature on the performance of sub-2-microm porous particles. (United States)

    Fountain, Kenneth J; Neue, Uwe D; Grumbach, Eric S; Diehl, Diane M


    The effects of extra-column band spreading, LC system operating pressure, and separation temperature were investigated for sub-2-microm particle columns using both a conventional HPLC system as well as a UPLC system. The contributions of both volume- and time-based extra-column effects were analyzed in detail. In addition, the performance difference between columns containing 2.5 and 1.7-microm particles (same stationary phase) was studied. The performance of these columns was compared using a conventional HPLC system and a low dead volume UPLC system capable of routine operation up to 1000 bar. The system contribution to band spreading and the pressure limitations of the conventional HPLC system were found to be the main difficulties that prevented acceptable performance of the sub-2-microm particle columns. Finally, an increase in operating temperature needs to be accompanied by an increase in flow rate to prevent a loss of separation performance. Thus, at a fixed column length, an increase in temperature is not a substitute for the need for very high operating pressures.

  3. Flow rate dependent extra-column variance from injection in capillary liquid chromatography. (United States)

    Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L


    Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23 nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ∼130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used.

  4. Effect of pre- and post-column band broadening on the performance of high-speed chromatography columns under isocratic and gradient conditions. (United States)

    Vanderlinden, Kim; Broeckhoven, Ken; Vanderheyden, Yoachim; Desmet, Gert


    We report on the results of an experimental and theoretical study of the effect of the extra-column band broadening (ECBB) on the performance of narrow-bore columns filled with the smallest particles that are currently commercially available. Emphasis is on the difference between the effect of ECBB under gradient and isocratic conditions, as well as on the ability to model and predict the ECBB effects using well-established band broadening expressions available from the theory of chromatography. The fine details and assumptions that need to be taken into account when using these expressions are discussed. The experiments showed that, the steeper the gradient, the more pronounced the extra-column band broadening losses become. Whereas the pre-column band broadening can in both isocratic and gradient elution be avoided by playing on the possibilities to focus the analytes on top of the column (e.g. by using the POISe injection method when running isocratic separations), the post-column extra-column band broadening is inescapable in both cases. Inducing extra-column band broadening by changing the inner diameter of the post-column tubing from 65 to 250 μm, we found that all peaks in the chromatogram are strongly affected (around a factor of 1.9 increase in relative peak width) when running steep gradients, while usually only the first eluting peak was affected in the isocratic mode or when running shallow gradients (factor 1.6-1.8 increase in relative peak width for the first eluting analyte).

  5. Mass transfer kinetics, band broadening and column efficiency. (United States)

    Gritti, Fabrice; Guiochon, Georges


    Important progress was recently made in our understanding of the physico-chemical aspects of mass transfer kinetics in chromatographic columns, in methods used for accurate determination of the different contributions to the height equivalent to a theoretical plate (HETP), and in the application of these advances to the elucidation of mass transfer mechanisms in columns packed with recent chromatographic supports (sub-2 μm fully porous particles, sub-3 μm core-shell particles, and monoliths). The independent contributions to the HETP are longitudinal diffusion, eddy dispersion, liquid-solid mass transfer (including trans-particle or trans-skeleton mass transfer and external film mass transfer), and the contributions caused by the thermal heterogeneity of the column. The origin and importance of these contributions are investigated in depth. This work underlines the areas in which improvements are needed, an understanding of the contribution of the external film mass transfer term, a better design of HPLC instruments providing a decrease of the extra-column band broadening contributions to the apparent HETP, the development of better packing procedures giving more radially homogeneous column beds, and new packing materials having a higher thermal conductivity to eliminate the nefarious impact of heat effects in very high pressure liquid chromatography (vHPLC) and supercritical fluid chromatography (SFC).

  6. Measurement and Modeling of Extra-Column Effects Due to Injection and Connections in Capillary Liquid Chromatography

    Directory of Open Access Journals (Sweden)

    James P. Grinias


    Full Text Available As column volumes continue to decrease, extra-column band broadening has become an increasingly important consideration when determining column performance. Combined contributions due to the injector and connecting tubing in a capillary LC system were measured and found to be larger than expected by Taylor-Aris theory. Variance from sigma-type and tau-type broadening was isolated from eluted peaks using the Foley-Dorsey Exponentially Modified Gaussian peak fitting model and confirmed with computational fluid dynamics. It was found that the tau-type contributions were the main cause for the excessive broadening because of poorly-swept volumes at the connection between the injector and tubing. To reduce tau-type contributions (and peak tailing, a timed pinch mode could be used for analyte injection.

  7. Analysis of compressive failure of layered materials by kink band broadening

    DEFF Research Database (Denmark)

    Jensen, Henrik Myhre


    Failure by steady state kink band broadening in uni-directional fibre composites or layered materials is analysed. An incremental scheme for calculation of kink band broadening stresses and lock-up conditions in the band for arbitrary material behaviour is presented. The method is illustrated...

  8. Extra-column dispersion of macromolecular solutes in aqueous-phase size-exclusion chromatography. (United States)

    Grznárová, G; Polakovic, M; Acai, P; Görner, T


    A set of dextran standards was used to study the extra-column dispersion in conventional chromatographic equipment at a broad range of molecular weights, different mobile phase flow rates and connecting tube lengths and diameters. All known correlations for the tube dispersion at laminar flow, including those for short tubes, overestimated the values of the variance of the outlet concentration signal. The difference increased with the solute molecular weight and the flow rate. It was assumed that the discrepancy was due to the effect of natural convection invoked by the density differences of the injected dextran solutions and water. A suitable approximation of the relative band spreading was suggested in a form of a power function of the Reynolds and Schmidt numbers. A significant decrease of the dispersion was observed when the chromatography tubing was coiled into a circle. This decrease was successfully predicted combining the existing correlations for long coiled tubes and short straight tubes.

  9. Reducing pulsewidth broadening in L-band EDFAs by use of a new L-band EDF

    DEFF Research Database (Denmark)

    Yu, Jianjun; Jeppesen, Palle; Palsdottir, Bera;


    Due to a small effective area of erbium-doped fiber (EDF), a short pulse will be broadened because of self-phase modulation when it is amplified in an L-band EDF amplifier (EDFA); hence, it is necessary to develop a new EDF with large Er3+ concentration to reduce the EDF length and a large...... effective area to reduce the nonlinear effect in the L-band EDFA. In this letter, it will be demonstrated that the pulsewidth can be maintained when a short pulse is amplified in an L-band EDFA consisting of a new L-band EDF....

  10. Design and realization of a magnetic-type absorber with a broadened operating frequency band

    Institute of Scientific and Technical Information of China (English)

    Zhou Yong-Jiang; Pang Yong-Qiang; Cheng Hai-Feng


    In this paper,we present an efficient method to obtain absorbers with broadened operating frequency bands.They are accomplished by using conventional magnetic absorbing materials (MAMs) in the forms of array and mesh structures,which are similar to those in the case of a frequency selective surface.The proposed approach is verified not only by simulations but also by experimental results under the normal incidence at microwave frequencies.Moreover,the wideband absorber is lighter than the conventional magnetic absorber.These results indicate that our proposed absorbing structures can be used for designing good electromagnetic absorbers.

  11. Thermal broadening of Lb band of ``trehalose coated'' tyrosine and phenylalanine (United States)

    Carrotta, Rita; Sanfratello, Vincenzo; Leone, Maurizio; Cordone, Lorenzo


    We studied the thermal broadening of Lb band of tyrosine and phenylalanine embedded in a trehalose matrix. Aim of this work is to obtain information on the effects of "trehalose coating" on the coupling of the electronic transition to low frequency modes in the surrounding of the chromophore. The results obtained for the two molecular complexes put in evidence that O-H groups are involved in blocking these structures within the solid trehalose matrix and shed light on the role played by hydrogen bonds on the interactions that keep "trehalose coated" proteins rigid and solid-like.

  12. [Effect of an anomalous broadening of the synchronization band after electric stimulation of heart tissues]. (United States)

    Mazurov, M E


    Synchronization effects of the second order induced by a change of the action potential (AP) shape in relation to the frequency of periodic stimulation were studied. Mechanism of anomalous increase of the synchronization band at periodic stimulation of the heart fibers was explained. By means of a modified method of synchronization diagrams the synchronization bands were calculated for possible stimulation regimes taking into account a change in RP shape and dynamic threshold (DT) depending on the frequency of the initiated regimes. Regions of stimulating signals parameters (multiplicity regions or prolonging regions) were discovered, within the range of which the same stimulating signal may induce different synchronization regimes. Physiological meaning of the existence of anomalous synchronization regimes which significantly broaden the adaptation possibilities of the heart is discussed.

  13. Line parameters for CO2 broadening in the ν2 band of HD16O (United States)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Crawford, Timothy J.; Gamache, Robert R.; Renaud, Candice L.; Smith, Mary Ann H.; Mantz, Arlan W.; Villanueva, Geronimo L.


    CO2-rich planetary atmospheres such as those of Mars and Venus require accurate knowledge of CO2 broadened HDO half-width coefficients and their temperature dependence exponents for reliable abundance determination. Although a few calculated line lists have recently been published on HDO-CO2 line shapes and their temperature dependences, laboratory measurements of those parameters are thus far non-existent. In this work, we report the first measurements of CO2-broadened half-width and pressure-shift coefficients and their temperature dependences for over 220 transitions in the ν2 band. First measurements of self-broadened half-width and self-shift coefficients at room temperature are also obtained for majority of these transitions. In addition, the first experimental determination of collisional line mixing has been reported for 11 transition pairs for HDO-CO2 and HDO-HDO systems. These results were obtained by analyzing ten high-resolution spectra of HDO and HDO-CO2 mixtures at various sample temperatures and pressures recorded with the Bruker IFS-125HR Fourier transform spectrometer at the Jet Propulsion Laboratory (JPL). Two coolable absorption cells with path lengths of 20.38 cm and 20.941 m were used to record the spectra. The various line parameters were retrieved by fitting all ten spectra simultaneously using a multispectrum nonlinear least squares fitting algorithm. The HDO transitions in the 1100-4100 cm-1 range were extracted from the HITRAN2012 database. For the ν2 and 2ν2 -ν2 bands there were 2245 and 435 transitions, respectively. Modified Complex Robert-Bonamy formalism (MCRB) calculations were made for the half-width coefficients, their temperature dependence and the pressure shift coefficients for the HDO-CO2 and HDO-HDO collision systems. MCRB calculations are compared with the measured values.

  14. Experimental and Theoretical He-BROADENED Line Parameters of Carbon Monoxide in the Fundamental Band (United States)

    Predoi-Cross, Adriana; Rosario, Hoimonti; Esteki, Koorosh; Latif, Shamria; Naseri, Hossein; Thibault, Franck; Devi, V. Malathy; Smith, Mary Ann H.; Mantz, Arlan


    We report experimental measurements and theoretical calculations for He-broadened Lorentz half-width coefficients and He- pressure-shift coefficients of 45 carbon monoxide transitions in the 1-0 band. The high-resolution spectra analyzed in this study were recorded over a range of sample temperatures between 296 and 80 K. The He-broadened line parameters and their temperature dependences were retrieved using a multispectrum nonlinear least squares analysis program. A previous analysis of these spectra used only the Voigt line shape. In the present study four line shape models were compared including Voigt, speed dependent Voigt, Rautian (to take into account confinement narrowing) and Rautian with speed dependence. The line mixing coefficients have been calculated using the Exponential Power Gap scaling law. We were unable to retrieve the temperature dependence of the line mixing coefficients. The current measurements and theoretical results are compared with other published results, where appropriate. A. W. Mantz et al., J. Molec. Structure 742 (2005) 99-110

  15. Intensities, broadening and narrowing parameters in the ν3 band of methane

    KAUST Repository

    Es-sebbar, Et-touhami


    The P-branch of methane\\'s ν3 band is probed to carry out an extensive study of the 2905-2908cm-1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001cm-1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.

  16. Spectroscopic Study of Air-Broadened Nitrous Oxide in the ν_3 Band (United States)

    Hashemi, Robab; Naseri, Hossein; Predoi-Cross, Adriana; Smith, Mary Ann H.; Devi, V. Malathy


    We present results of a recent analysis of laboratory spectra to determine line positions, intensities, air-broadened half-widths and pressure-induced shifts and their temperature dependences in the ν_3 fundamental band of N_2O. The spectra used in this study were recorded using the 1-m McMath-Pierce Fourier transform spectrometer while it was located at the National Solar Observatory on Kitt Peak, AZ. Multispectrum analysis software was used to retrieve the line parameters using the Voigt and speed-dependent Voigt line profiles. The line mixing coefficients were calculated using the Exponential Power Gap scaling law. Comparisons with similar published results will be presented. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith, D. Atkins, JQSRT 53 (1995) 705-721.

  17. Broadening of effective photonic band gaps in biological chiral structures: From intrinsic narrow band gaps to broad band reflection spectra (United States)

    Vargas, W. E.; Hernández-Jiménez, M.; Libby, E.; Azofeifa, D. E.; Solis, Á.; Barboza-Aguilar, C.


    Under normal illumination with non-polarized light, reflection spectra of the cuticle of golden-like and red Chrysina aurigans scarabs show a structured broad band of left-handed circularly polarized light. The polarization of the reflected light is attributed to a Bouligand-type left-handed chiral structure found through the scarab's cuticle. By considering these twisted structures as one-dimensional photonic crystals, a novel approach is developed from the dispersion relation of circularly polarized electromagnetic waves traveling through chiral media, to show how the broad band characterizing these spectra arises from an intrinsic narrow photonic band gap whose spectral position moves through visible and near-infrared wavelengths.

  18. - and H_2-BROADENED Line Parameters of Carbon Monoxide in the First Overtone Band (United States)

    Predoi-Cross, Adriana; Esteki, Koorosh; Naseri, Hossein; Devi, V. Malathy; Smith, Mary Ann H.; Mantz, Arlan; Ivanov, Sergei V.


    In this study we have re-analyzed high-resolution spectra of pure CO and CO broadened by hydrogen recorded in the spectral range of the first overtone band. We have used four different line shapes in the multispectrum analysis (Voigt, speed dependent Voigt, Rautian, and Rautian with speed dependence) and compared the resulting line shape parameters. The line mixing coefficients have been calculated using the Exponential Power Gap and the Energy Corrected Sudden scaling laws. A classical approach was applied to calculate CO line widths in CO-H_2 and CO-CO collisions. The formulas of classical impact theory are used for calculation of dipole absorption half-widths along with exact 3D Hamilton equations for simulation of molecular motion. The calculations utilize Monte Carlo averaging over collision parameters and simple interaction potential (Tipping-Herman + electrostatic). Molecules are treated as rigid rotors. The dependences of CO half-widths on rotational quantum number J≤ 24 are computed and compared with measured data at room temperature. V. Malathy Devi et al., J. Mol. Spectrosc. 228 (2004) 580-592. R. G. Gordon, J. Chem. Phys. 44 (1966) 3083-3089; ibid., 45 (1966) 1649-1655. J.-P. Bouanich and A. Predoi-Cross, J. Molec. Structure 742 (2005) 183-190 A. Predoi-Cross, J.-P. Bouanich, D. Chris Benner, A. D. May, and J. R. Drummond, J. Chem. Phys. 113 (2000) 158-168

  19. Pressure broadening, -shift, speed dependence and line mixing in the ν3 rovibrational band of N2O (United States)

    Loos, Joep; Birk, Manfred; Wagner, Georg


    In this paper, we report measured air-broadening, -shift, speed dependence and Rosenkranz line mixing parameters for the ν3 fundamental rovibrational band of N2O. A Bruker IFS 125HR Fourier transform spectrometer was used with a White-type multipass absorption cell with 46.4 m absorption path length to measure four ambient temperature air-broadened absorption spectra at total pressures ranging from 100 to 1000 mbar. A multispectrum fitting technique was used to retrieve parameters up to |m|=40 (m=-J″ and m=J″+1 for the P and R branch, respectively) utilizing the partially correlated quadratic speed-dependent hard collision model including Rosenkranz line mixing. Speed dependence of the broadening parameter as well as line mixing could be observed in the spectra. The broadening parameters are compared to HITRAN2012, where deviations can be ascribed to the influence of neglecting speed dependence effects in spectra analyses when using the Voigt line profile. The line mixing coefficients show a smooth dependence on m.

  20. Theoretical and revisited experimentally retrieved He-broadened line parameters of carbon monoxide in the fundamental band (United States)

    Predoi-Cross, A.; Esteki, K.; Rozario, H.; Naseri, H.; Latif, S.; Thibault, F.; Malathy Devi, V.; Smith, M. A. H.; Mantz, A. W.


    We report revisited experimentally retrieved and theoretically calculated He-broadened Lorentz half-width coefficients and He- pressure-shift coefficients of 45 carbon monoxide transitions in the 1←0 band. The spectra analyzed in this study were recorded over a range of temperatures between 79 and 296 K. The He-broadened line parameters and their temperature dependences were retrieved using a multispectrum nonlinear least squares analysis program. The line shape models used in this study include Voigt, speed dependent Voigt, Rautian (to take into account confinement narrowing) and Rautian with speed dependence, all with an asymmetric component added to account for weak line mixing effects. We were unable to retrieve the temperature dependence of line mixing coefficients. A classical method was used to determine the He-narrowing parameters while quantum dynamical calculations were performed to determine He-broadening and He-pressure shifts coefficients at different temperatures. The line mixing coefficients were also derived from the exponential power gap law and the energy corrected sudden approximation. The current measurements and theoretical results are compared with other published results, where appropriate.

  1. CO2 pressure broadening and shift coefficients for the 2-0 band of 12C16O (United States)

    Hashemi, R.; Predoi-Cross, A.; Dudaryonok, A. S.; Lavrentieva, N. N.; Vandaele, A. C.; Vander Auwera, J.


    Fourier transform absorption spectra of the 2-0 band of 12C16O mixed with CO2 have been recorded at total pressures from 156 to 1212 hPa and at 4 different temperatures between 240 K and 283 K. CO2 pressure-induced line broadening and line shift coefficients, and the temperature dependence of the former have been measured including line mixing using a multi-spectrum non-linear least squares fitting technique. Different line shape models have been considered to take into account the Dicke narrowing or speed dependence effects. Measured line-shape parameters were compared with theoretical values, calculated for individual temperatures using a semi-empirical method and the Exponential Power Gap (EPG) law.

  2. Broadening of Omnidirectional Photonic Band Gap in Graphene Based one Dimensional Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Neetika Arora


    Full Text Available A simple design of one dimensional gradual stacked photonic crystal has been proposed. This structure exhibits a periodic array of alternate layers of Graphene and Silica. These are the materials of low and high refractive indices respectively. Here the structure considered has three stacks .Each stack has five alternate layers of Graphene and silica. The transfer matrix method has been used for numerical computation. In this paper, such a structure has wider reflection bands in comparison to a conventional dielectric PC structure and structure with Sio2 and Si layers for a constant gradual constant ϒ at different incident angle.

  3. Measurements of linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene in the ν4+ν5 combination band using a cw quantum cascade laser

    KAUST Repository

    Sajid, Muhammad Bilal


    Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 combination band and other vibrational bands of acetylene. © 2014 Elsevier Ltd.

  4. Temperature dependences of self- and N2-broadened line-shape parameters in the ν3 and ν5 bands of 12CH3D: Measurements and calculations (United States)

    Predoi-Cross, A.; Malathy Devi, V.; Sutradhar, P.; Sinyakova, T.; Buldyreva, J.; Sung, K.; Smith, M. A. H.; Mantz, A. W.


    This paper presents the results of a spectroscopic line shape study of self- and nitrogen-broadened 12CH3D transitions in the ν3 and ν5 bands in the Triad region. We combined five pure gas spectra with eighteen spectra of lean mixtures of 12CH3D and nitrogen, all recorded with a Bruker IFS-125 HR Fourier transform spectrometer. The spectra have been analyzed simultaneously using a multispectrum nonlinear least squares fitting technique. N2-broadened line parameters for 184 transitions in the ν3 band and 205 transitions in the ν5 band were measured. In addition, line positions and line intensities were measured for 168 transitions in the ν3 band and 214 transitions in the ν5 band. We have observed 10 instances of weak line mixing corresponding to K″=3 A1 or A2 transitions. Comparisons were made for the N2-broadening coefficients and associated temperature exponents with corresponding values calculated using a semi-classical Robert Bonamy type formalism that involved an inter-molecular potential with terms corresponding to short- and long-range interactions, and exact classical molecular trajectories. The theoretical N2-broadened coefficients are overestimated for high J values, but are in good agreement with the experimental values for small and middle range J values.

  5. Singular value decomposition of genome-scale mRNA lengths distribution reveals asymmetry in RNA gel electrophoresis band broadening. (United States)

    Alter, Orly; Golub, Gene H


    We describe the singular value decomposition (SVD) of yeast genome-scale mRNA lengths distribution data measured by DNA microarrays. SVD uncovers in the mRNA abundance levels data matrix of genes x arrays, i.e., electrophoretic gel migration lengths or mRNA lengths, mathematically unique decorrelated and decoupled "eigengenes." The eigengenes are the eigenvectors of the arrays x arrays correlation matrix, with the corresponding series of eigenvalues proportional to the series of the "fractions of eigen abundance." Each fraction of eigen abundance indicates the significance of the corresponding eigengene relative to all others. We show that the eigengenes fit "asymmetric Hermite functions," a generalization of the eigenfunctions of the quantum harmonic oscillator and the integral transform which kernel is a generalized coherent state. The fractions of eigen abundance fit a geometric series as do the eigenvalues of the integral transform which kernel is a generalized coherent state. The "asymmetric generalized coherent state" models the measured data, where the profiles of mRNA abundance levels of most genes as well as the distribution of the peaks of these profiles fit asymmetric Gaussians. We hypothesize that the asymmetry in the distribution of the peaks of the profiles is due to two competing evolutionary forces. We show that the asymmetry in the profiles of the genes might be due to a previously unknown asymmetry in the gel electrophoresis thermal broadening of a moving, rather than a stationary, band of RNA molecules.

  6. Self- and N2-broadening of CH3Br ro-vibrational lines in the ν2 band: The J and K dependence (United States)

    Boussetta, Z.; Kwabia Tchana, F.; Aroui, H.


    Methyl bromide (CH3Br) is the major source of inorganic bromine in the atmosphere and contributes significantly to ozone depletion. Indeed, CH3Br is dissociated by UV radiation, producing Br radicals that catalyze the destruction of ozone. In this paper, we report measured Lorentz self- and N2-broadening coefficients of CH3Br in the ν2 fundamental band using a mono-spectrum non-linear least squares fitting of Voigt profiles which appeared to properly model the observed molecular line shapes within the noise level. These measurements were made by analyzing 12 laboratory absorption spectra recorded at high resolution (0.005, 0.003 or 0.002 cm-1) using the Fourier transform spectrometer Bruker IF125HR located at the LISA facility in Créteil. The spectra were obtained at room temperature using a White-type multipass cell with an optical path of 0.849 m and various pressures. We have been able to determine the self- and N2-broadening coefficients of 948 ν2 transitions with quantum numbers as high as J = 49 and K = 10. The measured self-broadening coefficients range from 0.1542 to 0.4930 cm-1 atm-1 and the N2-broadening coefficients range from 0.0737 to 0.1284 cm-1 atm-1 at 295 K. The accuracy of the broadening coefficients measured in this work is between 4% and 8%, depending on the studied transition. Comparisons with measurements taken in the ν5 and ν6 bands of CH3Br did not show any clear vibrational dependence. The J and K dependences of the self- and N2-broadening coefficients have been observed and the rotational K dependence has been modeled using empirical polynomial expression. On average, the empirical expression reproduce the measured broadening coefficients to within 6%. The data obtained represent a significant contribution to the determination of broadening coefficients of CH3Br useful for atmospheric remote sensing and applications. Note: The assignment column gives the isotopologue (79 for CH379Br and 81 for CH381Br) for which the transition is

  7. Saturation Dip Measurements of High-J Transitions in the v_1+v_3 Band of C_2H_2: Absolute Frequencies and Self-Broadening (United States)

    Sears, Trevor; Twagirayezu, Sylvestre; Hall, Gregory


    Saturation dip spectra of acetylene in the v_1 + v_3 band have been obtained for rotational lines with J = 31-37 inclusive, using a diode laser referenced to a frequency comb. The estimated accuracy and precision of the measurements is better than 10 kHz in 194 THz. Data were obtained as a function of sample pressure to investigate the broadening of the saturation features. The observed line shapes are well modeled by convolution of a fixed Gaussian transit-time and varying Lorentzian lifetime broadening, i.e. a Voigt-type profile. The lines exhibit a significantly larger collisional (lifetime) broadening than has been measured in conventional Doppler and pressure-broadened samples at ambient temperatures. The figure shows the fitted Lorentzian width versus sample pressure for P(31). The slope of this plot gives the pressure broadening coefficient, γ_{self} = 9.35(13) MHz/mbar. For comparison, the coefficient derived from conventional Doppler and pressure broadened spectra for this transition is 2.7 MHz/mbar. The sub-Doppler broadening coefficients are all significantly larger than the conventionally measured ones, due to the increased importance of velocity-changing collisions. The measurements therefore give information on the balance between hard phase- or state-changing and large cross-section velocity-changing collisions. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences and Biosciences within the Office of Basic Energy Sciences. J. Molec. Spectrosc. 209, 216-227 (2001) and J. Quant. Spectrosc. Rad. Transf. 76, 237-267 (2003)

  8. Collision induced broadening of ν1 band and ground state spectral lines of sulfur dioxide perturbed by N2 and O2 (United States)

    Ceselin, Giorgia; Tasinato, Nicola; Puzzarini, Cristina; Charmet, Andrea Pietropolli; Stoppa, Paolo; Giorgianni, Santi


    To monitor the constituents and trace pollutants of Earth atmosphere and understand its evolution, accurate spectroscopic parameters are fundamental information. SO2 is produced by both natural and anthropogenic sources and it is one of the principal causes of acid rains as well as an important component of fine aerosol particles, once oxidized to sulfate. The present work aims at determining SO2 broadening parameters using N2 and O2 as atmospherically relevant damping gases. Measurements are carried out in the infrared (IR) and mm-/sub-mm wave regions, around 8.8 μm and in the 104 GHz-1.1 THz interval, respectively. IR ro-vibrational transitions are recorded by using a tunable diode laser spectrometer, whereas the microwave spectra are recorded by using a frequency-modulated millimeter-/submillimeter-wave spectrometer. SO2-N2 and SO2-O2 collisional cross sections are retrieved for several ν1 band ro-vibrational transitions of 32S16O2, for some transitions belonging to either ν1 + ν2 - ν2 of 32S16O2 or ν1 of 34S16O2 as well as for about 20 pure rotational transitions in the vibrational ground state of the main isotopic species. From N2- and O2- broadening coefficients the broadening parameters of SO2 in air are derived. The work is completed with the study of the dependence of foreign broadening coefficients on the rotational quantum numbers.

  9. Intensities and self-broadening coefficients of the strongest water vapour lines in the 2.7 and 6.25 μm absorption bands (United States)

    Ptashnik, Igor V.; McPheat, Robert; Polyansky, Oleg L.; Shine, Keith P.; Smith, Kevin M.


    Intensities and self-broadening coefficients are presented for about 460 of the strongest water vapour lines in the spectral regions 1400-1840 cm-1 and 3440-3970 cm-1 at room temperature, obtained from rather unique measurements using a 5-mm-path-length cell. The retrieved spectral line parameters are compared with those in the HITRAN database ver. 2008 and 2012 and with recent ab-initio calculations. Both the retrieved intensities and half-widths are on average in reasonable agreement with those in HITRAN-2012. Maximum systematic differences do not exceed 4% for intensities (1600 cm-1 band) and 7% for self-broadening coefficients (3600 cm-1 band). For many lines however significant disagreements were detected with the HITRAN-2012 data, exceeding the average uncertainty of the retrieval. In addition, water vapour line parameters for 5300 cm-1 (1.9 μm) band reported by us in 2005 were also compared with HITRAN-2012, and show average differences of 4-5% for both intensities and half-widths.

  10. Theory of controlling band-width broadening in terahertz sideband generation in semiconductors by a direct current electric field (United States)

    Liu, Houquan; Zhang, Xingchu


    In a semiconductor, optically excited electron-hole pairs, driven by a strong terahertz (THz) field, can recombine to create THz sidebands in the optical spectrum. The sideband spectrum exhibits a "plateau" up to a cutoff frequency of 3.17Up, where Up is the ponderomotive energy. In this letter, we predict that the bandwidth of this sideband spectrum plateau can be broadened by applying an additional direct-current (DC) electric field. We find that if applying a DC field of EDC=0.2ETHz (where EDC and ETHz are the amplitudes of the DC field and THz field, respectively), the sideband spectrum presents three plateaus with 5.8Up, 10.05Up and 16Up being the cutoff frequencies of the first, second and third plateaus, respectively. This bandwidth broadening occurs because the DC field can increase the kinetic energy that an electron-hole pair can gain from the THz field. This effect means that the bandwidth of the sideband spectrum can be controlled flexibly by changing the DC field, thereby facilitating the ultrafast electro-optical applications of THz sideband generation.

  11. Spectroscopic Line Parameters of - and Hydrogen-Broadened 12C16O Transitions in the 3-0 Band from 6270 wn to 6402 wn. (United States)

    Reed, Zachary; Hodges, Joseph T.


    We present helium- and hydrogen-broadened linewidths, pressure-induced shifts, and collisional narrowing coefficients for selected lines in the P- and R- branch of the second overtone (3-0) band of CO, spanning from 6270 wn to 6402 wn. The contribution of speed dependent effects and partial correlation between velocity-changing and dephasing collisions on the foreign broadened line shapes are also discussed. The data were obtained using the frequency-stabilized cavity ringdown spectroscopy technique. Spectra were collected at room temperature over a pressure range from 13.3 kPa to 100 kPa. The spectrum frequency axis is referenced via an optical frequency comb to a Cs clock, which provides pressure shifting values with uncertainties as low as 100 kHz/atm. The spectra exhibited signal-to-noise ratios as high as 20,000:1, which enables rigorous tests of theoretical line profiles through multi-spectrum least squares data analysis. The partially correlated, quadratic-speed-dependent Nelkin Ghatak profile gives a quality of fit mostly commensurate with the high spectrum signal-to-noise and minimizes structural residuals.

  12. Chain-length-dependent impact of band broadening on the molar-mass determination of synthetic polymers via size-exclusion chromatography. (United States)

    Wolpers, Arne; Vana, Philipp


    The impact of band-broadening (BB) on the molar-mass determination of synthetic polymers via size-exclusion chromatography (SEC) is systematically studied. BB is simulated using the exponentially modified Gaussian (EMG) model, which combines the two inherent and distinct characteristics contributing to BB in SEC: symmetric Gaussian broadening and asymmetric skewing. It is demonstrated that BB both during the measurement of the analyte itself and during the calibration process has an individual impact on molar-mass determination. In this context, particularly skewing leads to a chain-length-dependent underestimation of molar masses, with deviations of the apparent from the true ones of only a few percent for low molar masses to up to 20% for high ones for reasonable extents of BB. The impact is shown to be independent of the shape of the analyte⬢s molar-mass distribution (MMD) and affects broad and multimodal MMDs similarly to narrow and unimodal ones. As a consequence, strategies are presented for a comprehensive quantitative correction of the observed effects, which may find their application in refined SEC software packages. The potential impact of the findings on general conceptions of repeatability and reproducibility within SEC experiments is discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Particle shape inhomogeneity and plasmon-band broadening of solar-control LaB{sub 6} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Machida, Keisuke; Adachi, Kenji, E-mail: [Ichikawa Research Laboratories, Sumitomo Metal Mining Co., Ltd., Ichikawa 272-8588 (Japan)


    An ensemble inhomogeneity of non-spherical LaB{sub 6} nanoparticles dispersion has been analyzed with Mie theory to account for the observed broad plasmon band. LaB{sub 6} particle shape has been characterized using small-angle X-ray scattering (SAXS) and electron tomography (ET). SAXS scattering intensity is found to vary exponentially with exponent −3.10, indicating the particle shape of disk toward sphere. ET analysis disclosed dually grouped distribution of nanoparticle dispersion; one is large-sized at small aspect ratio and the other is small-sized with scattered high aspect ratio, reflecting the dual fragmentation modes during the milling process. Mie extinction calculations have been integrated for 100 000 particles of varying aspect ratio, which were produced randomly by using the Box-Muller method. The Mie integration method has produced a broad and smooth absorption band expanded towards low energy, in remarkable agreement with experimental profiles by assuming a SAXS- and ET-derived shape distribution, i.e., a majority of disks with a little incorporation of rods and spheres for the ensemble. The analysis envisages a high potential of LaB{sub 6} with further-increased visible transparency and plasmon peak upon controlled particle-shape and its distribution.

  14. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. (United States)

    Hao, Feng; Stoumpos, Constantinos C; Chang, Robert P H; Kanatzidis, Mercouri G


    Perovskite-based solar cells have recently been catapulted to the cutting edge of thin-film photovoltaic research and development because of their promise for high-power conversion efficiencies and ease of fabrication. Two types of generic perovskites compounds have been used in cell fabrication: either Pb- or Sn-based. Here, we describe the performance of perovskite solar cells based on alloyed perovskite solid solutions of methylammonium tin iodide and its lead analogue (CH3NH3Sn(1-x)Pb(x)I3). We exploit the fact that, the energy band gaps of the mixed Pb/Sn compounds do not follow a linear trend (the Vegard's law) in between these two extremes of 1.55 and 1.35 eV, respectively, but have narrower bandgap (Pb ratio. Our results show that CH3NH3Sn(0.5)Pb(0.5)I3 has the broadest light absorption and highest short-circuit photocurrent density ~20 mA cm(-2) (obtained under simulated full sunlight of 100 mW cm(-2)).

  15. Tunable diode laser measurement of self and foreign broadening and shift versus temperature of seven ammonia transitions of the v{sub 2} band

    Energy Technology Data Exchange (ETDEWEB)

    Baldacchini, G.; D`Amato, F. [ENEA, Centro Ricerche Frascati, Rome (Italy); Buffa, G.; Tarrini, O. [Pis, Univ. (Italy). Dip. di Fisica; De Rosa, M.; Pelagalli, F.


    Self broadening and self shift coefficients have been measured as a function of temperature in the range from 200 to 400 K for seven ammonia transitions in the v{sub 2} band near 900 cm{sup -1}. Among these, one (near 921 cm {sup -1}) has been used to study the broadening and shift coefficients induced by several foreign gas as N{sub 2}, O{sub 2}, Air, H{sub 2}, Ar, He, as a function of temperature from 180 to 400 K. The results have been compared with semiclassical calculations relying on the impact approximation. The main results are that the modifies Anderson-Tsao-Curnutte theory describes very well the self broadening but has some limitations for self shift and foreign gas measurements. Moreover, this theory does not agree well with the empirical laws describing the temperature behaviours, especially when wide temperature ranges are involved. On the other hand these empirical laws are completely at odd in those cases when the shift coefficient changes its sign versus temperature as it`s observed in this work. [Italiano] Sono stati misurati i coefficienti di allargamento e spostamento in funzione della temperatura nell`intervallo da 200 a 400 K per sette transizioni nella banda v{sub 2} dell`ammoniaca intorno a 900 cm{sup -1}. Una tra queste (a{approx}921 cm{sup -1}) e` stata usata per studiare i coefficienti di allargamento e spostamento indotti dalle collisioni con diversi altri gas, come N{sub 2}, O{sub 2}, Aria, H{sub 2}, Ar, He, in funzione della temperatura da 180 a 400 K. I risultati sono stati confrontati con calcoli semiclassici basati sull`approssimazione dell`impatto. I principali risultati sono che la teoria modificata di Anderson-Tsao-Curnutte descrive molto bene l`allargamento ma presenta alcuni limiti con lo spostamento e le misure con gas diversi. Inoltre questa teoria non si accorda bene con le leggi empiriche che descrivono gli andamenti con la temperatura, in particolare quando si considerano ampi intervalli di temperatura. D`altra parte le

  16. Spectral Line Shape Parameters for the ν_1, ν_2, and ν_3 Bands of Hdo: Self and CO_2 Broadened (United States)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Crawford, Timothy J.; Gamache, Robert R.; Renaud, Candice L.; Mantz, Arlan; Smith, Mary Ann H.; Villanueva, Geronimo L.


    To provide precise information relevant to Martian atmospheric remote sensing, high resolution high signal-to-noise ratio spectra of HDO in mixture with CO_2 were recorded in the ν_1, ν_2, and ν_3 fundamental bands between 2.7 and 7 μm regions. The spectra were obtained with the Bruker IFS-125HR Fourier transform spectrometer at the Jet Propulsion Laboratory along with two specially built coolable absorption cells with path lengths of 0.2038 m and 20.941 m at various sample gas temperatures (˜220 - 296 K), total sample pressures and volume mixing ratios. A multispectrum nonlinear least squares technique was applied to fit simultaneously all the spectra obtained. The measured line parameters include accurate line positions, intensities, self- and CO_2-broadened Lorentz halfwidth and pressure-shift coefficients, and temperature dependences of CO_2 broadened HDO halfwidth and pressure-shift coefficients. Line mixing coefficients using the relaxation matrix formalism and quadratic speed dependence parameters were also measured where appropriate. Example results for select transitions in each band will be presented and comparisons made to other measured/calculated values. K. Sung, A.W. Mantz, M.A.H. Smith, L.R. Brown, T.J. Crawford, V.M. Devi, D.C. Benner. J. Mol. Spectrosc. 162 (2010) 124-134. A.W. Mantz, K. Sung, T.J. Crawford, L.R. Brown, M.A.H. Smith, V.M. Devi, D.C. Benner, J. Mol. Spectrosc. 304 (2014) 12-24. D.C. Benner, C.P. Rinsland, V. Malathy Devi, M.A. H. Smith, and D. Atkins. JQSRT 53 (1995) 705-721. Research described in this paper are performed at the College of William and Mary, Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and NASA Langley Research Center under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG and CLR were supported by the National Science Foundation through Grant # AGS-1156862.

  17. On the relationship between band broadening and the particle-size distribution of the packing material in liquid chromatography: theory and practice. (United States)

    Gritti, Fabrice; Farkas, Tivadar; Heng, Josuah; Guiochon, Georges


    The influence of the particle size distribution (PSD) on the band broadening and the efficiency of packed columns is investigated on both theoretical and practical viewpoints. Each of the classical contributions to mass transfer kinetics, those due to longitudinal diffusion, eddy dispersion, and solid-liquid mass transfer resistance are measured and analyzed in terms of their expected and observed intensity as a function of the PSD of mixtures of the commercially available packing materials, 5 and 3 μm Luna-C₁₈ particles (Phenomenex, Torrance, CA, USA). Six 4.6 mm × 150 mm columns were packed with different mixtures of these two materials. The efficiencies of these columns were measured for a non-retained and a retained analytes in a mixture of acetonitrile and water. The longitudinal diffusion coefficient was directly measured by the peak parking method. The solid-liquid mass transfer coefficient was measured from the combination of the peak parking method, the best model of effective diffusion coefficient and the actual PSDs of the different particle mixtures measured by Coulter counter experiments. The eddy diffusion term was measured according to a recently developed protocol, by numerical integration of the peak profiles. Our results clearly show that the PSD has no measurable impact on any of the coefficients of the van Deemter equation. On the contrary and surprisingly, adding a small fraction of large particles to a batch of small particles can improve the quality of the packing of the fine particles. Our results indirectly confirm that the success of sub-3 μm shell particles is due to the roughness of their external surface, which contributes to eliminate most of the nefarious wall effects. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Experimental and numerical validation of the effective medium theory for the B-term band broadening in 1st and 2nd generation monolithic silica columns. (United States)

    Deridder, Sander; Vanmessen, Alison; Nakanishi, Kazuki; Desmet, Gert; Cabooter, Deirdre


    Effective medium theory (EMT) expressions for the B-term band broadening in monolithic silica columns are presented at the whole-column as well as at the mesoporous skeleton level. Given the bi-continuous nature of the monolithic medium, regular as well as inverse formulations of the EMT-expressions have been established. The established expressions were validated by applying them to a set of experimental effective diffusion (Deff)-data obtained via peak parking on a number of 1st and 2nd generation monolithic silica columns, as well as to a set of numerical diffusion simulations in a simplified monolithic column representation (tetrahedral skeleton model) with different external porosities and internal diffusion coefficients. The numerically simulated diffusion data can be very closely represented over a very broad range of zone retention factors (up to k″=80) using the established EMT-expressions, especially when using the inverse variant. The expressions also allow representing the experimentally measured effective diffusion data very closely. The measured Deff/Dmol-values were found to decrease significantly with increasing retention factor, in general going from about Deff/Dmol=0.55 to 0.65 at low k″ (k″≅1.5-3.8) to Deff/Dmol=0.25 at very high k″ (k″≅40-80). These values are significantly larger than observed in fully-porous and core-shell particles. The intra-skeleton diffusion coefficient (Dpz) was typically found to be of the order of Dpz/Dmol=0.4, compared to Dpz/Dmol=0.2-0.35 observed in most particle-based columns. These higher Dpz/Dmol values are the cause of the higher Deff/Dmol values observed. In addition, it also appears that the higher internal diffusion is linked to the higher porosity of the mesoporous skeleton that has a relatively open structure with relatively wide pores. The observed (weak) relation between Dpz/Dmol and the zone retention factor appears to be in good agreement with that predicted when applying the regular

  19. Corrigendum to "Measurement and computations for temperature dependences of self-broadened carbon dioxide transitions in the 30012←00001 and 30013←00001 bands" [J. Quant. Spectrosc. Radiat. Transf., 111 (9) (2010) 1065-1079 (United States)

    Predoi-Cross, Adriana; Liu, W.; Murphy, Reba; Povey, Chad; Gamache, R.; Laraia, A.; McKellar, A. R. W.; Hurtmans, Daniel; Devi, V. M.


    The group of authors would like to make the following clarification: the retrievals of self-broadened temperature dependence coefficients were performed by the authors both using the multispectrum fit program from Ref. [14] and using the multispectrum fit program of D. Chris Benner [Benner DC, Rinsland CP, Devi VM, Smith MAH, Atkins D. A multispectrum nonlinear least-squares fitting technique. J. Quant. Spectrosc. Radiat. Transf. 1995;53:705-21.). To retrieve the room temperature self-broadening parameters, the authors have used the values in Ref. [4]. For reasons of consistency with the results published for air-broadening and air-shift temperature dependence coefficients in A. Predoi-Cross, A.R.W. McKellar, D. Chris Benner, V. Malathy Devi, R.R. Gamache, C.E. Miller, R.A. Toth, L.R. Brown, Temperature dependences for air-broadened Lorentz half width and pressure-shift coefficients in the 30013←00001 and 30012←00001 bands of CO2near 1600 μm, Canadian Journal of Physics, 87 (5) (2009) 517-535, Tables 2 and 3, and Figures 2 and 4 contain only the values retrieved using the multispectrum fit program of D. Chris Benner. We would like to thank D. Chris Benner for allowing us to use his fitting software.

  20. Quantum Cascade Laser Measurements of Line Intensities, N2-, O2- and Ar- Collisional Broadening Coefficients of N2O in the  3 Band Near 4.5  m

    KAUST Repository

    Es-sebbar, E.-t.


    This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth\\'s atmosphere. © The Author(s) 2016.

  1. First measurements of nitrous oxide self-broadening and self-shift coefficients in the 0002-0000 band at 2.26 μm using high resolution Fourier transform spectroscopy (United States)

    Werwein, Viktor; Brunzendorf, Jens; Serdyukov, Anton; Werhahn, Olav; Ebert, Volker


    Nitrous oxide (N2O) is one of the most important greenhouse gases in the terrestrial atmosphere and is routinely measured with ground-based FTIR networks like the Total Carbon Column Observing Network (TCCON). A spectral window for the TCCON retrievals is the 14N216O 0002-0000-band region from 4375 to 4445 cm-1 (2.250-2.285 μm). In our study, we present the first high-resolution Fourier transform spectrometer measurements of self-broadening and self-shift coefficients in the range of 53-1019 hPa for the lines R0e-R40e of this band. The line parameters were determined at 296 K using metrologically validated temperature, and pressure values, which were traced back to the SI-units. The averaged estimated relative uncertainties for the coverage factor of k = 2 (two times the standard deviation) are 0.3% and 9.5% with a standard deviation of 0.1% and 5.3% for the self-broadening and the self-shift coefficients, respectively. Vacuum line positions, determined for the first time by taking the self-shift coefficients into account are also reported with an estimated averaged relative uncertainty of 1.1 ∗ 10-8 for k = 2 and a standard deviation of 3 ∗ 10-9. A well-defined uncertainty assessment for the measured line parameters is given.

  2. Spectral shapes of Ar-broadened HCl lines in the fundamental band by classical molecular dynamics simulations and comparison with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tran, H., E-mail: [Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR CNRS 7583, Université Paris Est Créteil, Université Paris Diderot, Institut Pierre-Simon Laplace, 94010 Créteil Cedex (France); Domenech, J.-L. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, (IEM-CSIC), Serrano 123, 28006 Madrid (Spain)


    Spectral shapes of isolated lines of HCl perturbed by Ar are investigated for the first time using classical molecular dynamics simulations (CMDS). Using reliable intermolecular potentials taken from the literature, these CMDS provide the time evolution of the auto-correlation function of the dipole moment, whose Fourier-Laplace transform leads to the absorption spectrum. In order to test these calculations, room temperature spectra of various lines in the fundamental band of HCl diluted in Ar are measured, in a large pressure range, with a difference-frequency laser spectrometer. Comparisons between measured and calculated spectra show that the CMDS are able to predict the large Dicke narrowing effect on the shape of HCl lines and to satisfactorily reproduce the shapes of HCl spectra at different pressures and for various rotational quantum numbers.

  3. Absolute intensities and foreign gas broadening coefficients of the 11(sub 1,10) from 11(sub 2,10) and 18(sub 0,18) from 18(sub 1,18) lines in the nu(sub 7) band of C2H4 (United States)

    Reuter, Dennis C.; Sirota, J. Marcos


    Absolute intensities and foreign gas broadening coefficients of the 18(sub 0,18) from 18(sub 1,18) and 11(sub 1,10) from 11(sub 2,10) transitions in the nu(sub 7) band of C2H4 near 948/cm have been measured at a spectral resolution of approximately 5 x 10(exp -4)/cm using tunable diode laser spectrometry. Ar, He, N2, O2 were used as the broadening gases. In order to determine the temperature dependence of the broadening coefficient, data were obtained at temperatures ranging from 150 to 296 K. The absolute intensity of the 5(sub 0,5) from 5(sub 1,5) transition was also found at 296 K. A band strength of 330 +/- 10/sq cm/atm was obtained from weighted averages of the individual line intensities and a rigid asymmetric top calculation.

  4. Measurement of the Temperature Dependence of Line Mixing and Pressure Broadening Parameters between 296 and 90 K in the v3 band of 12CH4 and their Influence on Atmospheric Methane Retrievals (United States)

    Mondelain, Didier; Payan, Sebastien; Deng, Wenping; Camy-Peyret, Claude; Hurtmans, Daniel; Mantz, Arlan W.


    We measured the temperature dependence of the nitrogen broadening, narrowing and line-mixing coefficients of four lines of the P9 manifold in the v3 band of 12CH4 for atmospheric purposes. The data were collected using our tunable diode laser (TDL) spectrometer with active wavenumber control coupled to a newly developed cold Herriott cell with a path length of 5.37 m and a temperature uniformity of better than 0.01 K along the cell. We recorded and analyzed spectra recorded at sample temperature between 90 K and room temperature. We have investigate the influence of our new results in the inversion model used to retrieve methane profiles from atmospheric spectra; our new results make it possible to retrieve significantly more precise methane profiles. The atmospheric spectra we utilized were obtained by several of us with a balloon-born Fourier Transform infrared experiment in a limb configuration. Differences up to 7% on the retrieved volume mixing ratio were found compared to an inversion model using only HITRAN04 spectroscopic parameters.

  5. Measurement of the Temperature Dependence of Line Mixing and Pressure Broadening Parameters between 296 and 90 K in the v3 band of 12CH4 and their Influence on Atmospheric Methane Retrievals (United States)

    Mondelain, Didier; Payan, Sebastien; Deng, Wenping; Camy-Peyret, Claude; Hurtmans, Daniel; Mantz, Arlan W.


    We measured the temperature dependence of the nitrogen broadening, narrowing and line-mixing coefficients of four lines of the P9 manifold in the v3 band of 12CH4 for atmospheric purposes. The data were collected using our tunable diode laser (TDL) spectrometer with active wavenumber control coupled to a newly developed cold Herriott cell with a path length of 5.37 m and a temperature uniformity of better than 0.01 K along the cell. We recorded and analyzed spectra recorded at sample temperature between 90 K and room temperature. We have investigate the influence of our new results in the inversion model used to retrieve methane profiles from atmospheric spectra; our new results make it possible to retrieve significantly more precise methane profiles. The atmospheric spectra we utilized were obtained by several of us with a balloon-born Fourier Transform infrared experiment in a limb configuration. Differences up to 7% on the retrieved volume mixing ratio were found compared to an inversion model using only HITRAN04 spectroscopic parameters.

  6. Level Width Broaden Effect

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Shang


    In fitting the double-differential measurements thelevelwidth broadening effect should be taken into account properly due to Heisenberg uncertainty.Besides level width broadening effect the energy resolution in the measurements is also needed in this procedure.In general,the traditional normal Gaussian expansion is employed.However,the research indicates that to do so in this way the energy balance could not hold.For this reason,the deformed Gaussian expansion functions with exponential form for both the single energy point and continuous spectrum are introduced,with which the normalization and energy balance conditions could hold exactly in the analytical form.

  7. Alkaline broadening in Stars

    CERN Document Server

    De Kertanguy, A


    Giving new insight for line broadening theory for atoms with more structure than hydrogen in most stars. Using symbolic software to build precise wave functions corrected for ds;dp quantum defects. The profiles obtained with that approach, have peculiar trends, narrower than hydrogen, all quantum defects used are taken from atomic database topbase. Illustration of stronger effects of ions and electrons on the alkaline profiles, than neutral-neutral collision mechanism. Keywords : Stars: fundamental parameters - Atomic processes - Line: profiles.

  8. Band parameters for self-broadened ammonia gas in the range 0.74 to 5.24 μm to support measurements of the atmosphere of the planet Jupiter (United States)

    Bowles, Neil; Calcutt, Simon; Irwin, Pat; Temple, Jon


    We present new measurements and modelling of low-resolution transmission spectra of self-broadened ammonia gas, one of the most important absorbers found in the near-infrared spectrum of the planet Jupiter. These new spectral measurements were specifically designed to support measurements of Jupiter's atmosphere made by the Near-Infrared Mapping Spectrometer (NIMS) which was part of the Galileo mission that orbited Jupiter from 1995 to September 2003. To reach approximate jovian conditions in the lab, a new gas spectroscopy facility was developed and used to measure self-broadened ammonia spectra from 0.74 to 5.2 μm, virtually the complete range of the NIMS instrument, for the first time. Spectra were recorded at temperatures varying from 300 to 215 K, pressures from 1000 to 33 mb and using three different path lengths (10.164, 6.164 and 2.164 m). The spectra were then modelled using a series of increasingly complex physically based transmittance functions.

  9. S掺杂CuInSe2:导致的体积变化对其禁带宽度的影响%Impact of Lattice Volume on the Band Gap Broadening of Isovalent S-Doped CuInSe2

    Institute of Scientific and Technical Information of China (English)

    陈翔; 赵宇军; 姚若河; 何巨龙


    运用第一性原理方法研究了CulnSe2和不同量的S掺杂CulnSe2所形成的化合物的电子结构.理论计算表明,S掺杂导致CuInse2禁带宽度增大,且通过对其电子结构和键长的分析,发现因S掺杂浓度的增加而导致的CulnSeS化合物晶格体积减小对其禁带宽度的增加有重要的影响.%The electronic structure of pure and S-doped chalcopyrite CulnSe2 is investigated using a first-principles pseudopotential method in the generalized gradient approximation. The calculation indicates that the band gap of CulnSe2 broadens as S-doping concentration increases. We find that the decreased lattice volume due to isovalent S-doping in CulnSe2 has a significant impact on the band gap broadening phenomena. This physical insight is further discussed with the study of the electronic structure and bond length changes.

  10. Broadening nanotechnology's impact on development (United States)

    Beumer, Koen


    Discussions about nanotechnology and development focus on applications that directly address the needs of the world's poor. Nanotechnology can certainly make an impact in the fight against global poverty, but we need to broaden our imagination.

  11. Broadening nanotechnology's impact on development

    NARCIS (Netherlands)

    Beumer, K.


    Discussions about nanotechnology and development focus on applications that directly address the needs of the world’s poor. Nanotechnology can certainly make an impact in the fight against global poverty, but we need to broaden our imagination.

  12. Broadening nanotechnology's impact on development

    NARCIS (Netherlands)

    Beumer, K.


    Discussions about nanotechnology and development focus on applications that directly address the needs of the world’s poor. Nanotechnology can certainly make an impact in the fight against global poverty, but we need to broaden our imagination.

  13. Investigation of new band parameters with temperature dependence for self-broadened methane gas in the range 9000 to 14,000 cm-1 (0.71 to 1.1 μm) (United States)

    Bowles, Neil; Passmore, R.; Smith, K.; Williams, G.; Calcutt, S.; Irwin, P. G. J.


    This paper describes new measurements and modelling of the absorption of methane gas, one of the most important gases observed in the atmospheres of the outer planets and Titan, between 9000 and 14,000 cm-1 (0.7 to 1.1 μm) and compares them with current best available spectral models.A series of methane spectra were measured at the UK's Natural Environment Research Council (NERC) Molecular Spectroscopy Facility (based at the Rutherford Appleton Laboratory, Oxfordshire, UK) using a Brüker 125HR Fourier transform spectrometer. To approximate the conditions found in outer planet atmospheres, the spectra were measured over a wide range of pressures (5 bar to 38 mbar) and temperatures (290-100 K) with path lengths of 19.3, 17.6, 16.0 and 14.4 m. The spectra were recorded at a moderate resolution of 0.12 cm-1 and then averaged to 10 cm-1 resolution prior to fitting a series of increasingly complex band-models including temperature dependence. Using the most complex model, a Goody line distribution with a Voigt line shape and two lower energy state levels, the typical rms residual error in the fit is between 0.01 and 0.02 in the wings of the main absorption bands.The new spectral parameters were then compared with the measured spectra and spectra calculated using existing data and shown to be able to accurately reproduce the measured absorption. The improvement in the temperature dependence included in the model is demonstrated by comparison with existing cold methane spectral data for a typical Jovian path.

  14. Pressure broadening of rotational bands. I - A statistical theory (United States)

    Rosenkranz, P. W.


    Absorption of electromagnetic waves by rotational transitions of molecules is formulated for the case in which the wave frequency is displaced from resonance by an amount large compared to the reciprocal duration of a typical binary collision, and also large compared to the differences between frequencies of the strong resonances of the gas. In this far-wing limit, Fano's relaxation operator is reduced to a scalar parameter which depends on the frequency displacement. This relaxation parameter is not symmetric with respect to reflection about resonance, but becomes symmetric when multiplied by the factor exp (h/2pi) (omega sub d)/2kT where omega sub d is the frequency displacement. The theory applies to dipolar molecules of any shape, in collisions with either dipolar or quadrupolar molecules.

  15. Phonon broadening in high entropy alloys (United States)

    Körmann, Fritz; Ikeda, Yuji; Grabowski, Blazej; Sluiter, Marcel H. F.


    Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation high-temperature applications. At high temperatures, materials properties are strongly affected by lattice vibrations (phonons). Phonons critically influence thermal stability, thermodynamic and elastic properties, as well as thermal conductivity. In contrast to perfect crystals and ordered alloys, the inherently present mass and force constant fluctuations in multi-component random alloys (high entropy alloys) can induce significant phonon scattering and broadening. Despite their importance, phonon scattering and broadening have so far only scarcely been investigated for high entropy alloys. We tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys, from binaries up to 5-component high entropy alloys, addressing the key question of how chemical complexity impacts phonons. We find that it is crucial to include both mass and force constant fluctuations. If one or the other is neglected, qualitatively wrong results can be obtained such as artificial phonon band gaps. We analyze how the results obtained for the phonons translate into thermodynamically integrated quantities, specifically the vibrational entropy. Changes in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability considerations. The set of studied alloys includes MoTa, MoTaNb, MoTaNbW, MoTaNbWV, VW, VWNb, VWTa, VWNbTa, VTaNbTi, VWNbTaTi, HfZrNb, HfMoTaTiZr.

  16. Effective medium theory expressions for the effective diffusion in chromatographic beds filled with porous, non-porous and porous-shell particles and cylinders. Part II: Numerical verification and quantitative effect of solid core on expected B-term band broadening. (United States)

    Deridder, Sander; Desmet, Gert


    The results of a numerical simulation study of the diffusion and retention in fully porous spheres and cylinders are compared with some of the high order accuracy analytical solutions for the effective diffusion coefficient that have been derived from the effective medium theory (EMT) theory in part I of the present study. A variety of different ordered (spheres and cylinders) and disordered (cylinders) packings arrangements has been considered. The agreement between simulations and theory was always excellent, lying within the (very tight) accuracy limits of the simulations over the full range of retention factor and diffusion constant values that is practically relevant for most LC applications. Subsequently filling up the spheres and cylinders with a central solid core, while keeping the same packing geometry and the same mobile phase (same thermodynamic retention equilibrium), it was found that the core induces an additional obstruction which reduces the effective intra-particle diffusion coefficient exactly with a factor γ(part)=2/(2+ρ³) for spherical particles and γ(part)=1/(1+ρ²) for cylinders (ρ is the ratio of the core to the particle diameter, ρ=d(core)/d(part)). These expressions hold independently of the packing geometry, the value of the diffusion coefficients and the equilibrium constant or the size of the core. The expressions also imply that, if considering equal mobile phase conditions, the presence of the solid core will never reduce the particle contribution to the B-term band broadening with more than 33% (50% in case of cylindrical pillars). Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas. (United States)

    Paraskevaidis, Charilaos; Kuykendall, Tevye; Melli, Mauro; Weber-Bargioni, Alexander; Schuck, P James; Schwartzberg, Adam; Dhuey, Scott; Cabrini, Stefano; Grebel, Haim


    Using Surface Enhanced Raman Scattering (SERS), we report on intensity-dependent broadening in graphene-deposited broad-band antennas. The antenna gain curve includes both the incident frequency and some of the scattered mode frequencies. By comparing antennas with various gaps and types (bow-tie vs. diamond-shape antennas) we make the case that the line broadening did not originate from strain, thermal or surface potential. Strain, if present, further shifts and broadens those Raman lines that are included within the antenna gain curve.

  18. Characteristics of S-wave Envelope Broadening in the Changbaishan Tianchi Volcano

    Institute of Scientific and Technical Information of China (English)

    Fan Xiaoping; Li Qinghe; He Haibing; Yang Congjie; Jin Shumei


    High-frequency S-wave seismogram envelopes of microearthquakes broaden with increasing travel distance,a phenomenon known as S-wave envelope broadening.Multiple forward scattering and diffraction for the random inhomogeneities along the seismic ray path are the main causes of S-wave envelope broadening,so the phenomenon of S-wave envelope broadening is used to study the inhomogeneity of the medium.The peak delay time of an S-wave,which is defined as the time lag from the direct S-wave onset to the maximum amplitude arrival of its accepted to quantify S-wave envelope broadening.204 small earthquake records in Changbaishan Tianchi volcano were analyzed by the S-wave envelope broadening algorithm.The results show that S-wave envelope broadening in the Changbaishan Tianchi volcano is obvious,and that the peak delay time of S-wave has a positive correlation with the hypocenter distance and frequency of the Swave.The relationships between the S-wave peak delay time and the hypocenter distance for different frequency bands were obtained using the statistics method.The results are beneficial to the understanding of the S-wave envelope broadening phenomena and the quantitative research on the inhomogeneities of the crust medium in the Changbaishan Tianchi volcano region.

  19. Stark broadening of B IV spectral lines

    CERN Document Server

    Dimitrijevic, Milan S; Simic, Zoran; Kovacevic, Andjelka; Sahal-Brechot, Sylvie


    Stark broadening parameters for 157 multiplets of helium like boron (B IV) have been calculated using the impact semiclassical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series. An example of the influence of Stark broadening on B IV lines in DO white dwarfs is given.

  20. Stark broadening data for stellar plasma research. (United States)

    Dimitrijević, M. S.

    Results of an effort to provide to astrophysicists and physicists an as much as possible complete set of Stark broadening parameters needed for stellar opacity calculations, stellar atmosphere modelling, abundance determinations and diagnostics of different plasmas in astrophysics, physics and plasma technology, are presented. Stark broadening has been considered within the semiclassical perturbation, and the modified semiempirical approaches.

  1. Thermally induced microstrain broadening in hexagonal zinc

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, Andrew C [Los Alamos National Laboratory; Valdez, James A [Los Alamos National Laboratory; Roberts, Joyce A [Los Alamos National Laboratory; Leineweber, Andreas [STUTTGART, GERMANY; Mittemeijer, E J [STUTTGART, GERMANY; Kreher, W [DRESDEN UNIV


    Neutron powder-diffraction experiments on polycrystalline hexagonal zinc show considerable temperature-dependent line broadening. Whereas as-received zinc at 300 K exhibits narrow reflections, during cooling to a minimum temperature of 10K considerable line-broadening appears, which largely disappears again during reheating. The line broadening may be ascribed to microstrains induced by thermal microstresses due to the anisotropy of the thermal expansion (shrinkage) of hexagonal zinc. Differences between the thermal microstrains and theoretical predictions considering elastic deformation of the grains can be explained by plastic deformation and surface effects.

  2. Unified classical path theories of pressure broadening. (United States)

    Bottcher, C.


    Derivation of a unified classical path theory of pressure broadening, using only elementary concepts. It is shown that the theory of Smith, Cooper and Vidal (1969) is only correct at all frequencies to first order in the number density of perturbers.

  3. Line Broadening and the Solar Opacity Problem (United States)

    Krief, M.; Feigel, A.; Gazit, D.


    The calculation of line widths constitutes theoretical and computational challenges in the calculation of opacities of hot, dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions. Moreover, calculations of atomic spectra of the Sun indicate a large discrepancy in the K-shell line widths between several atomic codes and the Opacity-Project (OP). In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line broadening. Variations in the solar opacity profile due to an increase of the Stark widths resulting from discrepancies with OP, are compared, in light of the solar opacity problem, with the required opacity variations of the present day Sun, as imposed by helioseismic and neutrino observations. The resulting variation profile is much larger than the discrepancy between different atomic codes, agrees qualitatively with the missing opacity profile, recovers about half of the missing opacity nearby the convection boundary, and has a little effect in the internal regions. Since it is hard to estimate quantitatively the uncertainty in the Stark widths, we show that an increase of all line widths by a factor of about ˜100 recovers quantitatively the missing opacity. These results emphasize the possibility that photoexcitation processes are not modeled properly, and more specifically, highlight the need for a better theoretical characterization of the line broadening phenomena at stellar interior conditions, and of the uncertainty due to the way it is implemented by atomic codes.

  4. Design of cavity-enhanced absorption cell for reducing transit-time broadening. (United States)

    Abe, Masashi; Iwakuni, Kana; Okubo, Sho; Sasada, Hiroyuki


    To reduce the linewidth of Lamb dips, we introduce a cavity-enhanced absorption cell (CEAC) coupled with a Gaussian beam with a 1.9-mm 1/e(2) radius at the beam waist for the reduction of transit-time broadening. We state that transit-time broadening depends only on the beam radius at the beam waist. This fact is useful for the design of the CEAC, and a pair of concave and convex mirrors is thereby employed. We have carried out sub-Doppler resolution spectroscopy of the ν(3) band of CH(4) and the ν(1) band of CH(3)D using a difference-frequency-generation source and the CEAC, and the recorded Lamb dips narrow to 80 kHz (HWHM).

  5. Broadening of dielectric response and sum rule conservation

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Daniel, E-mail: [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářká 2, 611 37 Brno (Czech Republic); CEITEC —Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Nečas, David; Zajíčková, Lenka [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářká 2, 611 37 Brno (Czech Republic); CEITEC —Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Ohlídal, Ivan [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářká 2, 611 37 Brno (Czech Republic)


    Different types of broadening of the dielectric response are studied with respect to the preservation of the Thomas–Reiche–Kuhn sum rule. It is found that only the broadening of the dielectric function and transition strength function conserve this sum rule, whereas the broadening of the transition probability function (joint density of states) increases or decreases the sum. The effect of different kinds of broadening is demonstrated for interband and intraband direct electronic transitions using simplified rectangular models. It is shown that the broadening of the dielectric function is more suitable for interband transitions while broadening of the transition strength function is more suitable for intraband transitions. - Highlights: • Preservation of the sum rule by different types of dielectric response broadening • Only broadening of dielectric function and transition strength function preserves it. • Broadening of joint density of states does not preserve the sum rule. • Broadening of dielectric function is better for direct interband transitions. • Broadening of transition strength is better for indirect interband transitions.

  6. Pressure broadening and fine-structure-dependent predissociation in oxygen B-3 Sigma(-)(u), v=0

    NARCIS (Netherlands)

    Hannemann, S.; Wu, G.; Duijn, van E.J.; Ubachs, W.M.G.; Cosby, P.C.


    Both laser-induced fluorescence and cavity ring-down spectral observations were made in the Schumann-Rungeb and system of oxygen, using a novel-type ultranarrow deep-UV pulsed laser source. From measurements on the very weak (0,0) band pressure broadening, pressure shift, and predissociation line-br

  7. Commitment to Broadening Participation at NOAO (United States)

    Garmany, Catharine D.; Norman, D.


    AURA and NOAO take seriously the importance of Broadening Participation in Astronomy. At the request of the AURA President, each of the AURA centers (NOAO, NSO, STSCI, Gemini) appointed a Diversity Advocates (DA). At NOAO this job is shared by Dara Norman and Katy Garmany, who were appointed by Dave Silva in Jan 2009. The DA's are members of the AURA Committee on Workforce and Diversity (WDC), a designated subcommittee of the AURA Board of Directors. The role of this committee includes reviewing activities and plans on an AURA wide basis aimed at broadening the participation within AURA, and reviewing AURA wide policies on the workforce. At NOAO, the role of the DAs spans a number of departments and activities. They serve on observatory search committees, and offer suggestions on how NOAO job searches can reach the most diverse audience. The DA's job is to insure that NOAO actively pursues every opportunity to increase diversity: to this end they are involved in outreach and educational activities that focus on workplace development and encourage inclusion of woman, minorities and persons with disabilities.

  8. Action potential broadening in a presynaptic channelopathy (United States)

    Begum, Rahima; Bakiri, Yamina; Volynski, Kirill E.; Kullmann, Dimitri M.


    Brain development and interictal function are unaffected in many paroxysmal neurological channelopathies, possibly explained by homoeostatic plasticity of synaptic transmission. Episodic ataxia type 1 is caused by missense mutations of the potassium channel Kv1.1, which is abundantly expressed in the terminals of cerebellar basket cells. Presynaptic action potentials of small inhibitory terminals have not been characterized, and it is not known whether developmental plasticity compensates for the effects of Kv1.1 dysfunction. Here we use visually targeted patch-clamp recordings from basket cell terminals of mice harbouring an ataxia-associated mutation and their wild-type littermates. Presynaptic spikes are followed by a pronounced afterdepolarization, and are broadened by pharmacological blockade of Kv1.1 or by a dominant ataxia-associated mutation. Somatic recordings fail to detect such changes. Spike broadening leads to increased Ca2+ influx and GABA release, and decreased spontaneous Purkinje cell firing. We find no evidence for developmental compensation for inherited Kv1.1 dysfunction.

  9. Line broadening and the solar opacity problem

    CERN Document Server

    Krief, M; Gazit, D


    The calculation of line widths constitutes a theoretical as well as a computational challenge in the calculation of opacities of hot dense plasmas. Opacity models use line broadening approximations that are untested at stellar interior conditions. Moreover, calculations of atomic spectra nearby the convection zone boundary (CZB) of the sun, indicate a large discrepancy in the K-shell line widths between several atomic codes and the Opacity-Project. In this work, the atomic code STAR is used to study the sensitivity of solar opacities to line-broadening. Atomic spectra of several elements are analyzed and compared within the solar interior. Variations in the solar opacity profile due to changes in the Stark widths are shown to be significant and to result mainly due to K-shell lines. In light of the solar opacity problem, the results are compared with the required opacity variations of the present day sun, as imposed by helioseismic and neutrino observations. It is shown that an increase of the line widths res...

  10. Broadening the focus of evaluation: An experiment

    Directory of Open Access Journals (Sweden)

    Chakraborty, S.


    Full Text Available Evaluation of student performance in any course, especially those delivered in a management programme, poses a serious challenge; more so, in a course like ‘Business Communication’, where oral communication ought to form an integral part of evaluation. This paper presents various details of an experiment, conducted with a view to introduce this much needed component in the evaluation process. Essential purpose of the exercise was to try and broaden the focus of evaluation, simultaneously enlarging its scope. The need to maintain certain amount of objectivity and transparency was taken as critical. Group Discussion was used as a tool. A process was developed with the objective of getting every student evaluated on both written as well as non-written skills. A two-sided evaluation mechanism was put in place to achieve the dual purpose of leaning and evaluation. Statistical analysis of the results suggests that the experiment was a useful one. The student feedback, too, was favourable.

  11. Coherent Forward Broadening in Cold Atom Clouds

    CERN Document Server

    Sutherland, R T


    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Further, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single photon wave-function model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms in the back of the cloud are more excited than the atoms in the front. These calculations are conducted at low densities relevant to recent experiments.

  12. Radial velocity signatures of Zeeman broadening

    CERN Document Server

    Reiners, Ansgar; Anglada-Escude, Guillem; Jeffers, Sandra V; Morin, Julien; Zechmeister, Mathias; Kochukhov, Oleg; Piskunov, Nikolai


    Stellar activity signatures such as spots and plage can significantly limit the search for extrasolar planets. Current models of activity-induced radial velocity (RV) signals focused on the impact of temperature contrast in spots predicting the signal to diminish toward longer wavelengths. On the other hand, the relative importance of the Zeeman effect on RV measurements should grow with wavelength, because the Zeeman displacement itself grows with \\lambda, and because a magnetic and cool spot contributes more to the total flux at longer wavelengths. We model the impact of active regions on stellar RV measurements including both temperature contrast in spots and Zeeman line broadening. We calculate stellar line profiles using polarized radiative transfer models including atomic and molecular Zeeman splitting from 0.5 to 2.3\\mum. Our results show that the amplitude of the RV signal caused by the Zeeman effect alone can be comparable to that caused by temperature contrast. Furthermore, the RV signal caused by c...

  13. Hydrodynamic dispersion broadening of a sedimentation front (United States)

    Martin, J.; Rakotomalala, N.; Salin, D.


    Hydrodynamic dispersion is responsible for the spreading of the sedimentation front even in a noncolloidal monodisperse suspension. Measurements of the broadening of the top front observed during sedimentation have been used in determining the hydrodynamic dispersion coefficient. Hindered settling has an opposed effect and leads to the self-sharpening of the front. Both effects have to be taken into account simultaneously. This Letter provides a simple, but complete determination of the space and time concentration profile and shows that the final front should consist of a steady-shape profile propagating at constant velocity. With such a solution, the data of Davis et al. [AIChE J. 34, 123 (1988); J. Fluid Mech. 196, 107 (1988)] give hydrodynamic dispersion coefficient five times larger than their former analysis, in agreement with Lee et al. [Phys. Fluids A 4, 2601 (1992)].

  14. Stark Broadening in Compact Stars: Xe VI Lines

    Indian Academy of Sciences (India)

    Milan S. Dimitrijević; Zoran Simić; Andjelka Kovačević; Aleksandar Valjarević; Sylvie Sahal-Bréchot


    We will consider Stark broadening of non hydrogenic spectral lines in the impact approximation in compact stars: pre-white dwarf and white dwarf atmospheres. In order to show an example, Stark broadening parameters have been calculated, using the impact semiclassical perturbation approach for four Xe VI spectral lines. Obtained results have been used to demonstrate the influence of Stark broadening in DA and DB white dwarf atmospheres.

  15. Model, software and database for line-mixing effects in the {nu} {sub 3} and {nu} {sub 4} bands of CH{sub 4} and tests using laboratory and planetary measurements-I: N{sub 2} (and air) broadenings and the earth atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Tran, H. [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA, CNRS UMR 7583), Universite Paris XII, Avenue du General de Gaulle, Batiment 350, 94010 Creteil Cedex (France); Flaud, P.-M. [Laboratoire de Physico Chimie Moleculaire (LPCM UMR 5803), Universite Bordeaux 1, Bat. A12, 33405 Talence cedex (France); Gabard, T. [Laboratoire de Physique de l' Universite de Bourgogne (LPUB, CNRS UMR 5027), Faculte des Sciences Mirande, 9 Avenue Alain Savary, B.P. 47870, 21078 Dijon Cedex (France); Hase, F. [Forschungszentrum Karlsruhe, Institute of Meteorology and Climate research (IMK), P.O. Box 3640, D-76021 Karlsruhe (Germany); Clarmann, T. von [Forschungszentrum Karlsruhe, Institute of Meteorology and Climate research (IMK), P.O. Box 3640, D-76021 Karlsruhe (Germany); Camy-Peyret, C. [Laboratoire de Physique Moleculaire pour l' Atmosphere et l' Astrophysique (LPMAA, CNRS UMR 7092), Universite Pierre et Marie Curie, 4 Place Jussieu, Tour 13, Case 76, 75252 Paris Cedex 05 (France); Payan, S. [Laboratoire de Physique Moleculaire pour l' Atmosphere et l' Astrophysique (LPMAA, CNRS UMR 7092), Universite Pierre et Marie Curie, 4 Place Jussieu, Tour 13, Case 76, 75252 Paris Cedex 05 (France); Hartmann, J.-M. [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA, CNRS UMR 7583), Universite Paris XII, Avenue du General de Gaulle, Batiment 350, 94010 Creteil Cedex (France)]. E-mail:


    Absorption spectra of the infrared {nu} {sub 3} and {nu} {sub 4} bands of CH{sub 4} perturbed by N{sub 2} over large ranges of pressure and temperature have been measured in the laboratory. A theoretical approach accounting for line mixing is proposed to (successfully) model these experiments. It is similar to that of Pieroni et al. [J Chem Phys 1999;110:7717-32] and is based on state-to-state rotational cross-sections calculated with a semi-classical approach and a few empirical parameters. The latter, which enable switching from the state space to the line space, are deduced from a fit of a single room temperature spectrum of the {nu} {sub 3} band at 50 atm. The comparisons between numerous measured and calculated spectra under a vast variety of conditions ({nu} {sub 3} and {nu} {sub 4}, 0-500 atm, 170-300 K) then demonstrate the quality and consistency of the proposed model. This success is a first validation of a database and associated software built in order to model the shape of CH{sub 4} absorption in air, that are available and suitable for the updating of atmospheric radiative transfer codes. The accuracy of these tools is then further demonstrated using transmission measurements of the Earth atmosphere in the {nu} {sub 3} region (3 {mu}m) recorded in solar absorption with ground and balloon based Fourier transform instruments. Similar tests in the {nu} {sub 4} region using satellite based emission spectra and ground-based transmission measurements confirm the model quality although they show very small line-mixing effects and their masking by strong contributions of other species.

  16. Resonance linewidth and inhomogeneous broadening in a metamaterial array

    CERN Document Server

    Jenkins, Stewart D


    We examine the effect of inhomogeneous broadening on the collective response of a planar metamaterial consisting of asymmetric split ring resonators. We show that such a response leads to a transmission resonance that can persist when the broadening of individual meta-atom resonance frequencies is roughly one half the frequency characterizing the split ring asymmetry. We also find that larger degrees of inhomogeneous broadening can drastically alter the cooperative response, destroying this resonance. The reduced effect of cooperative response due to inhomogeneous broadening may find applications in producing metamaterial samples that more closely mimic homogeneous magneto-dielectric medium with well-defined susceptibility and permittivity.

  17. Measurements of self-broadening of infrared absorption lines of ozone (United States)

    Smith, M. A. H.; Rinsland, C. P.; Devi, V. M.


    Lorentz self-broadening coefficients have been determined for 355 spectral lines belonging to five different infrared vibration-rotation bands of O3 in the spectral region from 4.8 to 17 microns. Six ozone absorption spectra, recorded at room temperature using a Fourier transform spectrometer, were analyzed. The half-width values were obtained through a nonlinear least-squares spectral fitting procedure. The results are compared with previous measurements, and the vibration of the half-widths with vibrational and rotational quantum numbers is examined.

  18. Resonance broadening of argon lines in a micro-scaled atmospheric pressure plasma jet (argon μAPPJ) (United States)

    Pipa, A. V.; Ionikh, Yu. Z.; Chekishev, V. M.; Dünnbier, M.; Reuter, S.


    Optical emission from atmospheric pressure micro-jet operating with pure argon (argon μAPPJ) flow has been detected with a moderate resolution spectrometer. Large broadening of the several argon (Ar) lines has been observed in the near infrared spectral region. This effect was attributed to resonance broadening of the s2 (Paschen notation) level in 3p54s configuration. In the present work, corresponding line profiles are suggested for plasma diagnostics. For this, a general case of resonance broadening coefficient of noble gases is discussed. As broadening reflects the Ar density, and the static gas pressure of the jet is in equilibrium with the ambient, the local gas temperature can be inferred. An estimation of gas temperature from the width of the 750 nm Ar line is in agreement with rotational temperature of OH radicals determined from the A2Σ+ → X2Π (0, 0) band. At low temperatures (300-600 K) and at partial Ar pressure near atmospheric, the resonance width of the suggested lines is very sensitive to small temperature variations. High temperature sensitivity and large width make the resonance broadened lines very attractive for diagnostics of low temperature discharges at elevated pressure, e.g., as they are used in plasma-medicine.

  19. Correction of vibrational broadening in molecular dynamics clusters with the normal mode optimization method. (United States)

    Hudecová, Jana; Hopmann, Kathrin H; Bouř, Petr


    Vibrational properties of solutions are frequently simulated with clusters of a solute and a few solvent molecules obtained during molecular dynamics (MD) simulations. The raw cluster geometries, however, often provide unrealistic vibrational band broadening, for both ab initio and empirical force fields. In this work, partial optimization in normal-mode coordinates is used on empirical basis to reduce the broadening. The origin of the error is discussed on a simplified two-dimensional system, which indicates that the problem is caused by the anharmonic MD potential, mode coupling, and neglect of quantum effects. Then the procedure of partial geometry optimization on Raman and Raman optical activity (ROA) spectra is applied and analyzed for the solvated lactamide molecule. Comparison to experiment demonstrates that the normal-mode partial optimization technique with a suitable frequency limit can significantly reduce the broadening error. For lactamide, experimental and simulated vibrational bandwidths are compared; the most realistic theoretical spectra are obtained for partially optimized clusters with the vibrational wavenumber cutoff of about 200 cm(-1).

  20. Sensitivity Enhancement in Field-Modulated CW ENDOR via RF Bandwidth Broadening (United States)

    Hoffman, B. M.; Derose, V. J.; Ong, J. L.; Davoust, C. E.

    In low-temperature ENDOR studies it is common to modulate the magnetic field at ν mod ˜ 100 kHz and to observe the ENDOR response as a change in the dispersion-mode rapid-passage EPR signal as decoded at ν mod. The sensitivity of this procedure can be increased by incoherently broadening the bandwidth of the applied RF through mixing of the RF carrier signal with a white-noise source of variable bandwidth. This technique has been explored by monitoring the amplitude and width of ENDOR signals as a function of the RF bandwidth and power, in the case of the 57Fe signals from a metalloprotein and 14N, 1H signals from two Cu(II) compounds. The RF band broadening has produced signal enhancements of over threefold. The results are interpreted in terms of a competition between (i) an increase in the number of spin packets excited within the inhomogeneously broadened ENDOR line and () a reduction in the response per packet. Simple analysis leads to equations for the variation in the ENDOR response with incident RF power and bandwidth that are scaled by a saturation RF power and an effective spin-packet width, respectively.

  1. Temporal broadening of pulsed waves propagating through turbulent media

    Institute of Scientific and Technical Information of China (English)

    XU; Zhengwen(许正文); WU; Jian(吴健); HUO; Wenping(霍文平); WU; Zhensen(吴振森)


    Pulse signals, propagating through a turbulent medium such as the ionosphere, can be distorted by dispersion and scattering from both the background medium and irregularities embedded in. Thus, the mean square pulse width is changed, and temporal broadening is introduced. We carry out a study on the temporal broadening with theoretical analyses and numerical simulations by using an analytical solution of two-frequency mutual coherence function obtained recently by iteration. As a case of study, pulse broadening is investigated in detail in trans-ionospheric propagation. Results show that most contributions are mainly from the dispersion of the background ionosphere and scattering effects of electron density irregularities in most cases.

  2. Solar Wind Strahl Broadening by Self-Generated Plasma Waves (United States)

    Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.


    This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

  3. Spectroscopic properties of inhomogeneously broadened spin ensembles in a cavity

    DEFF Research Database (Denmark)

    Kurucz, Zoltan; Wesenberg, Janus; Mølmer, Klaus


    The enhanced collective coupling to weak quantum fields may turn atomic or spin ensembles into an important component in quantum information processing architectures. Inhomogeneous broadening can, however, significantly reduce the coupling and the lifetime of the collective excitation...

  4. Is macroturbulent broadening in OB Supergiants related to pulsations?

    CERN Document Server

    Simón-Díaz, S; Herrero, A; Castro, N; Puls, J; Aerts, C


    The spectrum of O and B Supergiants is known to be affected by an important extra line-broadening (usually called \\macro) that adds to stellar rotation. Recent analysis of high resolution spectra has shown that the interpretation of this line-broadening as a consequence of large-scale turbulent motions would imply highly super-sonic velocity fields, making this scenario quite improbable. Stellar oscillations have been proposed as a likely alternative explanation. We present first encouraging results of an observational project aimed at investigating the $macroturbulent$ broadening in O and B Supergiants, and its possible connection with spectroscopic variability phenomena and stellar oscillations: a) all the studied B Supergiants show line profile variations, quantified by means of the first () and third velocity () moments of the lines, b) there is a strong correlation between the peak-to-peak amplitudes of the and variability and the size of the extra-broadening.

  5. Meta-Research: Broadening the Scope of PLOS Biology. (United States)

    Kousta, Stavroula; Ferguson, Christine; Ganley, Emma


    In growing recognition of the importance of how scientific research is designed, performed, communicated, and evaluated, PLOS Biology announces a broadening of its scope to cover meta-research articles.

  6. Probing transverse momentum broadening in heavy ion collisions (United States)

    Mueller, A. H.; Wu, Bin; Xiao, Bo-Wen; Yuan, Feng


    We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark-gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet PT-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable PT-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the PT-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.

  7. Quasihomogeneous line broadening of a hydrogen-bonded polymer, investigated by picosecond infrared holeburning (United States)

    Graener, H.; Lösch, T.; Laubereau, A.


    Transient spectral holes with lifetimes of several picoseconds are investigated in the infrared absorption band of the OH stretching vibration of the terpolymer polyvinyl butyral. A large variation of the quasihomogeneous linewidth from 7-45 cm-1 is determined from the measured holewidth in the temperature range 80-330 K and interpreted in terms of anharmonic coupling to a low frequency mode ν2. The result ν2=135±8 cm-1 provides strong evidence for indirect dephasing via the OHṡṡṡO bridge stretching vibration. The inhomogeneous broadening of the total band is verified by the picosecond infrared holes. The inhomogeneity is related to an approximately static distribution of hydrogen bridges generated by local disorder and displays a different temperature behavior.

  8. Coherent and incoherent spectral broadening in a photonic crystal fiber. (United States)

    Gross, C; Best, Th; van Oosten, D; Bloch, I


    The coherence of the spectral broadening process is the key requisite for the application of supercontinua in frequency combs. We investigate the coherence of two subsequent supercontinuum pulses created in a photonic crystal fiber pumped by a femtosecond laser. We measure Young interference fringes from a Michelson-type interferometer at different wavelengths of the output spectrum and analyze their dependence on pump intensity and polarization. The visibility of these fringes is a direct measure of the coherence of the spectral broadening processes.

  9. Self-phase-modulation induced spectral broadening in silicon waveguides (United States)

    Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram


    The prospect for generating supercontinuum pulses on a silicon chip is studied. Using ~4ps optical pulses with 2.2GW/cm2 peak power, a 2 fold spectral broadening is obtained. Theoretical calculations, that include the effect of two-photon-absorption, indicate up to 5 times spectral broadening is achievable at 10x higher peak powers. Representing a nonlinear loss mechanism at high intensities, TPA limits the maximum optical bandwidth that can be generated.

  10. Self-phase-modulation induced spectral broadening in silicon waveguides. (United States)

    Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram


    The prospect for generating supercontinuum pulses on a silicon chip is studied. Using ~4ps optical pulses with 2.2GW/cm(2) peak power, a 2 fold spectral broadening is obtained. Theoretical calculations, that include the effect of two-photon-absorption, indicate up to 5 times spectral broadening is achievable at 10x higher peak powers. Representing a nonlinear loss mechanism at high intensities, TPA limits the maximum optical bandwidth that can be generated.

  11. Band broadening studies using the parameters for an exponentially modified Gaussian

    Energy Technology Data Exchange (ETDEWEB)

    Pauls, R. E.; Rogers, L. B.


    The effects on chromatographic peak shape of dead volume and flow rate have been examined using the standard deviation of the Gaussian component of the peak and the exponential decay constant. For a non-retained solute, addition of dead volume led to an increase in the standard deviation that was independent of flow rate while the decay constant was inversely proportional to the flow. Smaller changes were observed for a retained species.

  12. Fluid mechanics of electroosmotic flow and its effect on band broadening in capillary electrophoresis. (United States)

    Ghosal, Sandip


    Electroosmotic flow (EOF) usually accompanies electrophoretic migration of charged species in capillary electrophoresis unless special precautions are taken to suppress it. The presence of the EOF provides certain advantages in separations. It is an alternative to mechanical pumps, which are inefficient and difficult to build at small scales, for transporting reagents and analytes on microfluidic chips. The downside is that any imperfection that distorts the EOF profile reduces the separation efficiency. In this paper, the basic facts about EOF are reviewed from the perspective of fluid mechanics and its effect on separations in free solution capillary zone electrophoresis is discussed in the light of recent advances.

  13. Band Together! (United States)

    Olson, Cathy Applefeld


    After nearly a decade as band director at St. James High School in St. James, Missouri, Derek Limback knows that the key to building a successful program is putting the program itself above everything else. Limback strives to augment not only his students' musical prowess, but also their leadership skills. Key to his philosophy is instilling a…

  14. Detector resolution in positron annihilation Doppler broadening experiments (United States)

    Heikinheimo, J.; Ala-Heikkilä, J.; Tuomisto, F.


    Positron annihilation Doppler broadening spectroscopy characterizes lattice point defects and is sensitive to very small vacancy densities. High-purity germanium detectors are generally used for recording the Doppler broadening spectrum because they provide good energy resolution and stability. However, the energy resolution of a germanium detector is somewhat dependent on the photon absorption geometry in the detector crystal. This change in the energy resolution changes also the Doppler broadening parameters. To observe the dependency of the resolution function and the Doppler broadening parameters, we performed experiments on Si samples in standard sandwich configuration with a Na-22 source. We changed the radiation geometry of the incident gamma photons via altering the distance of the sample-source package from the detector and by adding steel between the source and the detector. We observed the change of the absorption geometry in the germanium detector crystal by doing Monte Carlo simulations. The aim of this study is to help understand and decide what is the best way to compare the Doppler broadening parameters obtained with different measurement setups and even with the same setup when the geometry in the measurements has changed.

  15. Stark Broadening Parameters for Neutral Oxygen Spectral Lines

    Indian Academy of Sciences (India)

    N. Alonizan; R. Qindeel; N. Ben Nessib; S. Sahal-Bréchot; Milan S. Dimitrijević


    Stark broadening parameters for nine neutral oxygen (O I) lines have been determined within the impact approximation and the semiclassical perturbation method. The atomic data have been taken from the TOPbase and NIST atomic databases. The electron and proton Stark widths and shifts and ion broadening parameter values for these O I lines have been calculated for electron density of 1016 cm$^{−3}$ and for 4 different electron temperatures in the range of 5000 K to 40000 K. These Stark broadening parameters are compared with our previous results (Ben Nessib, N. et al. 1996, Physica Scripta, 54, 603–613), where we calculated Stark broadening parameters for only four O I spectral lines and where Stark widths and shifts were compared with experimental and theoretical data available in the literature. In the present paper, we have also compared our results with the Griem's book (Griem, H. R. 1974, Spectral line broadening by plasmas) and VALD (Ryabchikova, T. et al. 2015, Physica Scripta, 90, 054005) values.

  16. Broadening of Transverse Momentum of Partons Propagating through a Medium

    CERN Document Server

    Johnson, M B; Tarasov, A V


    Broadening of the transverse momentum of a parton propagating through a medium is treated using the color dipole formalism, which has the advantage of being a well developed phenomenology in deep-inelastic scattering and soft processes. Within this approach, nuclear broadening should be treated as color filtering, i.e. absorption of large-size dipoles leading to diminishing (enlarged) transverse separation (momentum). We also present a more intuitive derivation based on the classic scattering theory of Moli\\`ere. This derivation helps to understand the origin of the dipole cross section, part of which comes from attenuation of the quark, while another part is due to multiple interactions of the quark. It also demonstrates that the lowest-order rescattering term provides an A-dependence very different from the generally accepted A^{1/3} behavior. The effect of broadening increases with energy, and we evaluate it using different phenomenological models for the unintegrated gluon density. Although the process is...

  17. Self- and N2-collisional broadening coefficients of ethylene in the 1800-2350 cm-1 spectral region (United States)

    Hassen, A. Ben; Galalou, S.; Tchana, F. Kwabia; Dhib, M.; Aroui, H.


    Self- and N2-broadening coefficients have been retrieved for 566 lines of C2H4 at room temperature in the 5 μm region including the ν7 + ν8, ν4 + ν8, ν6 + ν10, ν6 + ν7, ν4 + ν6 and ν3 + ν10 vibrational bands. Measurements have been performed using Fourier transform infrared spectroscopy. The lines were fitted with a single-spectrum non-linear least squares fitting procedure of Voigt profiles which appeared to properly model the observed molecular line shapes within the noise level. The experimental results are compared with theoretical values calculated using the Robert and Bonamy formalism which reproduces the measured broadening coefficients. For the self- and N2-broadening coefficients, the average discrepancy for 566 lines, is (-1.6 ± 7.8)% and (-2.8 ± 9.9)%, respectively. One standard deviation is given after ±. These coefficients show dependence with both rotational quantum numbers J and Ka. Comparisons with previous measurements taken in the ν7 band of C2H4 show difference range between 7% and 15%. These differences not insignificant can come from inconsistency between experimental measurements.

  18. Multigroup Free-atom Doppler-broadening Approximation. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Mark Girard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Multigroup cross sections at a one target temperature can be Doppler-broadened to multigroup cross sections at a higher target temperature by matrix multiplication if the group structure suf- ficiently resolves the original temperature continuous energy cross section. Matrix elements are the higher temperature group weighted averages of the integral over the lower temperature group boundaries of the free-atom Doppler-broadening kernel. The results match theory for constant and 1/v multigroup cross sections at 618 lanl group structure resolution.

  19. Inhomogeneous broadening in non-interacting nonlocal plasmonic ensembles

    DEFF Research Database (Denmark)

    Tserkezis, Christos; Maack, Johan Rosenkrantz; Liu, Z.


    The importance of inhomogeneous broadening due to the size dependence of plasmon resonances in few-nm metallic particle ensembles is investigated through different models describing the nonlocal optical response of plasmonic nanospheres. Modal shifts and plasmon line broadening are shown to become...... important within the first-order correction to classical electrodynamics provided by the hydrodynamic Drude model, but turn out to be less prominent once additional single-particle size-dependent damping mechanisms are accounted for through the recently developed Generalized Nonlocal Optical Response theory...

  20. Optical coherent control in semiconductors: Fringe contrast and inhomogeneous broadening

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher


    Optical coherent control experiments in semiconductors reveal how inhomogeneous broadening must be taken into account in contrast to previous coherent control experiments in atomic and molecular systems. With spectral resolution elf the coherent control signal, the optical phases involved...... is observed in the four-wave mixing spectra as a function of phase-delay representing coherent control in the spectral domain. The spectral phase change of this modulation provides a spectroscopic tool to analyze contributions of inhomogeneous broadening to electronic resonances in semiconductor structures....

  1. Combustion technology overview. [the use of broadened property aircraft fuels (United States)

    Niedzwiecki, R. W.


    An overview of combustor technology developments required for use of broadened property fuels in jet aircraft is presented. The intent of current investigations is to determine the extent to which fuel properties can be varied, to obtain a data base of combustion - fuel quality effects, and to determine the trade-offs associated with broadened property fuels. Subcomponents of in-service combustors such as fuel injectors and liners, as well as air distributions and stoichiometry, are being altered to determine the extent to which fuel flexibility can be extended. Finally, very advanced technology consisting of new combustor concepts is being evolved to optimize the fuel flexibility of gas turbine combustors.

  2. New band-notched UWB antenna

    Institute of Scientific and Technical Information of China (English)

    HE Xiao-xiang; DENG Hong-wei


    A simple and compact ultra wideband (UWB) printed monopole antenna with band-notched performance is proposed in this paper. The antenna is partially grounded so that the Q value is depressed and the impedance bandwidth is broadened. A small strip bar is loaded on each arm of the similar U-shaped radiator. The impedance bandwidth of the antenna overlap with IEEE 802.11a is rejected consequently. The geometry parameters of the antenna are investigated and optimized with HFSS. The measured bandwidth of the proposed antenna occupies about 7.89 GHz covering from 3.05 GHz to 10.94 GHz with expected notched band from 4.96 GHz to 5.98 GHz. A quasi-omnidirectional and quasi-symmetrical radiation pattern in the whole band is also obtained. As a result, a UWB wireless communication system can be simplified with the band-notched UWB antenna presented.

  3. An Experimental and Theoretical Study of Nitrogen-Broadened Acetylene Lines (United States)

    Thibault, Franck; Martinez, Raul Z.; Bermejo, Dionisio; Ivanov, Sergey V.; Buzykin, Oleg G.; Ma, Qiancheng


    We present experimental nitrogen-broadening coefficients derived from Voigt profiles of isotropic Raman Q-lines measured in the 2 band of acetylene (C2H2) at 150 K and 298 K, and compare them to theoretical values obtained through calculations that were carried out specifically for this work. Namely, full classical calculations based on Gordon's approach, two kinds of semi-classical calculations based on Robert Bonamy method as well as full quantum dynamical calculations were performed. All the computations employed exactly the same ab initio potential energy surface for the C2H2N2 system which is, to our knowledge, the most realistic, accurate and up-to-date one. The resulting calculated collisional half-widths are in good agreement with the experimental ones only for the full classical and quantum dynamical methods. In addition, we have performed similar calculations for IR absorption lines and compared the results to bibliographic values. Results obtained with the full classical method are again in good agreement with the available room temperature experimental data. The quantum dynamical close-coupling calculations are too time consuming to provide a complete set of values and therefore have been performed only for the R(0) line of C2H2. The broadening coefficient obtained for this line at 173 K and 297 K also compares quite well with the available experimental data. The traditional Robert Bonamy semi-classical formalism, however, strongly overestimates the values of half-width for both Qand R-lines. The refined semi-classical Robert Bonamy method, first proposed for the calculations of pressure broadening coefficients of isotropic Raman lines, is also used for IR lines. By using this improved model that takes into account effects from line coupling, the calculated semi-classical widths are significantly reduced and closer to the measured ones.

  4. Shear bands in a bulk metallic glass after large plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Qu, D.D.; Wang, Y.B.; Liao, X.Z.; Shen, J. (Harbin); (Sydney)


    A transmission electron microscopy investigation is conducted to trace shear bands in a Zr{sub 53}Cu{sub 18.7}Ni{sub 12}Al{sub 16.3} bulk metallic glass after experiencing 4% plastic deformation. Shear band initiation, secondary shear band interactions, mature shear band broadening and the interactions of shear bands with shear-induced nanocrystals are captured. Results suggest that the plasticity of the bulk metallic glass is enhanced by complex shear bands and their interactions which accommodate large plastic strain and prevent catastrophic shear band propagation.

  5. Non-Lorentzian diffusion-broadened Mössbauer lines

    DEFF Research Database (Denmark)

    Heilmann, Ian; Olsen, Boye; Jensen, Jens Højgaard


    Non-Lorentzian diffusion-broadened Mossbauer lines are reported for two different systems: (i) SnO, particles in silicon grease; and (ii) Fe(C,H,O,), dissolved in 1,3-propanediol. Both results are discussed as superpositions of Lorentzians each representing a particular situation of a Mossbauer...

  6. On the Fly Doppler Broadening Using Multipole Representation

    Energy Technology Data Exchange (ETDEWEB)

    Khassenov, Azamat; Choi, Sooyoung; Lee, Deokjung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)


    On the Fly Doppler broadening is the technique to avoid pre-generation of the microscopic cross section, in other words, reduce the amount of storage. Currently, there are different types of formalisms used by NJOY code to generate reaction cross section and accomplish its Doppler broadening. Single-Level Breit-Wigner (SLBW) formalism is limited to well-separated resonances, in other words, it does not consider interference between energy levels. Multi-Level Breit- Wigner formalism (MLBW) was tested as the candidate for the cross section generation in the Monte Carlo code, which is under development in UNIST. According to the results, MLBW method requires huge amount of computational time to produce cross section at certain energy point. Reich-Moore (RM) technique can generate only 0K cross section, which means that it cannot produce broaden cross section directly from resonance parameters. The first step was to convert resonance parameters given in nuclear data file into multipoles. MPR shows very high potential to be used as the formalism in the on-the-fly Doppler broadening module of MCS. One of the main reasons is that comparison of the time cost shown in Table IV supports application of multipole representation.

  7. The STARS Alliance: Viable Strategies for Broadening Participation in Computing (United States)

    Dahlberg, Teresa; Barnes, Tiffany; Buch, Kim; Rorrer, Audrey


    The Students and Technology in Academia, Research, and Service (STARS) Alliance is a nationally-connected system of regional partnerships among higher education, K-12 schools, industry and the community with a mission to broaden the participation of women, under-represented minorities and persons with disabilities in computing (BPC). Each regional…

  8. Coherent excitonic nonlinearity versus inhomogeneous broadening in single quantum wells

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Borri, Paola; Hvam, Jørn Märcher;


    The coherent response of excitons in semiconductor nanostructures, as measured in four wave mixing (FWM) experiments, depends strongly on the inhomogeneous broadening of the exciton transition. We investigate GaAs-AlGaAs single quantum wells (SQW) of 4 nm to 25 nm well width. Two main mechanisms...

  9. ECRH microwave beam broadening in the edge turbulent plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sysoeva, E. V.; Gusakov, E. Z.; Popov, A. Yu. [Ioffe Institute, St. Petersburg, Russia and RL PAT SPbSPU, St. Petersburg (Russian Federation); Silva, F. da [Institute of Plasmas and Nuclear Fusion, IST, Lisbon (Portugal); Heuraux, S. [IJL UMR-7198 CNRS-Université de Lorraine, BP70239, 54506 Vandoeuvre Cedex (France)


    The influence of turbulent plasma density fluctuations on angular and spatial beam width is treated analytically in the framework of WKB based eikonal method. Reasonable agreement of analytical and numerical treatment results is demonstrated within the domain of quasi-optical approximation validity. Significant broadening of microwave beams is predicted for future ECRH experiments at ITER.

  10. Pressure broadening of acetylene rotational Raman lines by argon


    Ceruti, M; Frenkel, D.; Mctaque, J.P.


    The anisotropic interaction between acetylene and argon has been studied by observing the density dependence of the acetylene pure rotational Raman line broadening. The observed cross sections are approximately twice that predicted from the known polarizabilities and acetylene molecular quadrupole moment. An empirical atom-atom anisotropic potential adequately parametrizes the results.

  11. Pressure broadening of acetylene rotational Raman lines by argon

    NARCIS (Netherlands)

    Ceruti, M.; Frenkel, D.; McTaque, J.P.


    The anisotropic interaction between acetylene and argon has been studied by observing the density dependence of the acetylene pure rotational Raman line broadening. The observed cross sections are approximately twice that predicted from the known polarizabilities and acetylene molecular quadrupole m

  12. Extending, Broadening and Rethinking Existing Research on Transfer of Training (United States)

    Volet, Simone


    The aim of this Special Issue was to generate a new integrated agenda for research on transfer of training. It brought together scholars from diverse perspectives and invited them to strive toward synergy. This article examines how this collection of articles, as well as other bodies of literature, can help extend, broaden and rethink current…

  13. GOLD: Building capacity for broadening participation in the Geosciences (United States)

    Adams, Amanda; Patino, Lina; Jones, Michael B.; Rom, Elizabeth


    The geosciences continue to lag other science, technology, engineering, and mathematics (STEM) disciplines in the engagement, recruitment and retention of traditionally underrepresented and underserved minorities, requiring more focused and strategic efforts to address this problem. Prior investments made by the National Science Foundation (NSF) related to broadening participation in STEM have identified many effective strategies and model programs for engaging, recruiting, and retaining underrepresented students in the geosciences. These investments also have documented clearly the importance of committed, knowledgeable, and persistent leadership for making local progress in broadening participation in STEM and the geosciences. Achieving diversity at larger and systemic scales requires a network of diversity "champions" who can catalyze widespread adoption of these evidence-based best practices and resources. Although many members of the geoscience community are committed to the ideals of broadening participation, the skills and competencies that empower people who wish to have an impact, and make them effective as leaders in that capacity for sustained periods of time, must be cultivated through professional development. The NSF GEO Opportunities for Leadership in Diversity (GOLD) program was implemented in 2016, as a funding opportunity utilizing the Ideas Lab mechanism. Ideas Labs are intensive workshops focused on finding innovative solutions to grand challenge problems. The ultimate aim of this Ideas Lab, organized by the NSF Directorate for Geosciences (GEO), was to facilitate the design, pilot implementation, and evaluation of innovative professional development curricula that can unleash the potential of geoscientists with interests in broadening participation to become impactful leaders within the community. The expectation is that mixing geoscientists with experts in broadening participation research, behavioral change, social psychology, institutional

  14. Peak broadening in paper chromatography and related techniques : III. Peak broadening in thin-layer chromatography on cellulose powder

    NARCIS (Netherlands)

    Ligny, C.L. de; Remijnse, A.G.


    The mechanism of peak broadening in thin-layer chromatography on cellulose powder was investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion in the cellulose powder, for a set of amino acids of widely differing RF values and six kinds of cellulose

  15. Peak broadening in paper chromatography and related techniques : III. Peak broadening in thin-layer chromatography on cellulose powder

    NARCIS (Netherlands)

    Ligny, C.L. de; Remijnse, A.G.


    The mechanism of peak broadening in thin-layer chromatography on cellulose powder was investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion in the cellulose powder, for a set of amino acids of widely differing RF values and six kinds of cellulose po

  16. Spectrally selective optical pumping in Doppler-broadened cesium atoms (United States)

    Zhang, Jun-Hai; Zeng, Xian-Jin; Li, Qing-Meng; Huang, Qiang; Sun, Wei-Min


    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations. The process, described by a three-level model with the Λ scheme, shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms. The |Fg = 3> → |Fe = 4> resonance pumping can result in the ground state |Fg = 4, mF = 4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg = 4. To enhance the anisotropy in the ground state, we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg = 4> → |Fe = 3> transition, in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  17. Positive emotions and the social broadening effects of Barack Obama. (United States)

    Ong, Anthony D; Burrow, Anthony L; Fuller-Rowell, Thomas E


    Past experiments have demonstrated that the cognitive broadening produced by positive emotions may extend to social contexts. Building on this evidence, we hypothesized that positive emotions triggered by thinking about Barack Obama may broaden and expand people's sense of self to include others. Results from an expressive-writing study demonstrated that African American college students prompted to write about Obama immediately prior to and after the 2008 presidential election used more plural self-references, fewer other-references, and more social references. Mediation analyses revealed that writing about Obama increased positive emotions, which in turn increased the likelihood that people thought in terms of more-inclusive superordinate categories (we and us rather than they and them). Implications of these findings for the role of positive emotions in perspective-taking and intergroup relations are considered.

  18. Stability analysis for bad cavity lasers with inhomogeneously broadened gain

    CERN Document Server

    Kazakov, Georgy A


    Bad cavity lasers are experiencing renewed interest in the context of active optical frequency standards, due to their enhanced robustness against fluctuations of the laser cavity. The gain medium would consist of narrow-linewidth atoms, either trapped inside the cavity or intersecting the cavity mode dynamically. A finite velocity distribution, atomic interactions, or interactions of realistic multilevel atoms with external field leads to an inhomogeneous broadening of the atomic gain profile. This can bring the bad cavity laser to operate in unstable regimes characterized by complex temporal patterns of the field amplitude. We present a new and efficient method for the stability analysis of bad cavity lasers with inhomogeneously broadened gain. We apply this method to identify the steady-state solutions for the metrology-relevant case of spin-1/2 atoms interacting with an external magnetic field.

  19. Collisional broadening of angular correlations in a multiphase transport model

    CERN Document Server

    Edmonds, Terrence; Wang, Fuqiang


    Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as a function of the number of parton-parton collisions suffered by a high transverse momentum probe parton ($N_{\\rm coll}$) and the azimuth of the probe relative to the reaction plane ($\\phi_{\\rm fin.}^{\\rm probe}$). Correlation is found to broaden with increasing $N_{\\rm coll}$ and $\\phi_{\\rm fin.}^{\\rm probe}$ from in- to out-of-plane direction. This study provides a transport model benchmark for future jet-medium interaction studies.

  20. Fundamental edge broadening effects during focused electron beam induced nanosynthesis

    Directory of Open Access Journals (Sweden)

    Roland Schmied


    Full Text Available The present study explores lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IVMe3 precursor. In particular, the scaling behavior of proximity effects as a function of the primary electron energy and the deposit height is investigated through experiments and validated through simulations. Correlated Kelvin force microscopy and conductive atomic force microscopy measurements identified conductive and non-conductive proximity regions. It was determined that the highest primary electron energies enable the highest edge sharpness while lower energies contain a complex convolution of broadening effects. Moreover, it is demonstrated that intermediate energies lead to even more complex proximity effects that significantly reduce lateral edge sharpness and thus should be avoided if desiring high lateral resolution.

  1. Attention and positive affect: temporal switching or spatial broadening? (United States)

    Phaf, R Hans


    Evolutionary reasoning and computation suggest that positive affect is associated with higher attentional flexibility than negative affect, even when affectively neutral material is processed. The affective modulation of interference in the Eriksen flanker task seems, however, more readily explained by a spatial broadening of attention due to positive affect. It is argued here that these results should also be interpreted in terms of an increased switching over time between flankers and target (i.e., flexibility). The two hypotheses were contrasted with positive and negative mood inductions in a masked-flanker task. The interval (Stimulus Onset Asynchrony; SOA) with which the masked flankers preceded the target letter was parametrically varied. In contrast to what is found with simultaneous non-masked flanker presentation, masking produced larger interference with negative than with positive moods. In addition, a crossover interaction between mood and SOA emerged. These results seem incompatible with a spatial broadening account and support an affective modulation account in terms of flexibility.

  2. Resonance broadening modification of weak plasma turbulence theory

    Energy Technology Data Exchange (ETDEWEB)

    Hanssen, A. (Max-Planck-Inst. fuer Aeronomie, Katlenburg-Lindau (West Germany))


    The author examines the effects on energy spectra of weak Langmuir turbulence when he includes a nonlinear damping due to the perturbation of electron orbits. The physical mechanism under consideration is usually known as a resonance broadening effect. The calculations show that the inclusion of this additional damping reduces the number of cascades predicted from weak turbulence theory for waves detectable with the EISCAT UHF (933 MHz) radar in Tromso, Norway, during RF modification of the ionospheric plasma.

  3. Density shift and broadening of transition lines in antiprotonic helium (United States)

    Bakalov; Jeziorski; Korona; Szalewicz; Tchoukova


    The density shift and broadening of the transition lines of antiprotonic helium have been evaluated in the impact approximation using an interatomic potential calculated ab initio with the symmetry-adapted perturbation theory. The results help to remove an uncertainty of up to 10 ppm in the laser spectroscopy data on antiprotonic helium and are of importance in experimental tests of bound state QED and CPT invariance.

  4. Amniotic constriction bands (United States)

    ... of function of an arm or a leg. Congenital bands affecting the hand often cause the most problems. Alternative Names Pseudo-ainhum; Streeter dysplasia; Amniotic band sequence; Amniotic constriction bands; Constriction band ...

  5. Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS (United States)

    Archambault, S.; Archer, A.; Benbow, W.; Buchovecky, M.; Bugaev, V.; Cerruti, M.; Connolly, M. P.; Cui, W.; Falcone, A.; Fernández Alonso, M.; Finley, J. P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Griffin, S.; Hütten, M.; Hervet, O.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Lin, T. T. Y.; Maier, G.; McArthur, S.; Moriarty, P.; Nieto, D.; O'Brien, S.; Ong, R. A.; Otte, A. N.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rovero, A. C.; Sadeh, I.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tyler, J.; Wakely, S. P.; Weinstein, A.; Weisgarber, T.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Zitzer, B.


    We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron-positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10-14 G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission.

  6. On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach

    Directory of Open Access Journals (Sweden)

    Milan S. Dimitrijević


    Full Text Available The significance of Stark broadening data for problems in astrophysics, physics, as well as for technological plasmas is discussed and applications of Stark broadening parameters calculated using a semiclassical perturbation method are analyzed.

  7. Regimes of Generation in Low-Q Distributed-Feedback Lasers with Strong Inhomogeneous Broadening of the Active Medium (United States)

    Kocharovskaya, E. R.; Ginzburg, N. S.; Sergeev, A. S.; Kocharovsky, V. V.; Kocharovsky, Vl. V.


    We study the influence of the ratio between the relaxation rates of the field in a cavity and the polarization of active centers on the dynamic properties of the distributed-feedback lasers by means of 1D numerical simulation. The model of a two-level active medium with strong inhomogeneous broadening of the spectral line under CW wide-band pumping that provides two- or several-mode lasing in the vicinity of the Bragg photonic band gap is used. Evolution of the dynamic spectra and oscillograms of the laser emission with decreasing Q-factor of the Bragg resonator is analyzed. It is shown, in particular, that under conditions of the dominant role of the superradiant effects, there are unique opportunities for control of both quantitative and qualitative characteristics of lasing, including the spectral width, duration, and coherence length of various pulse components of the output radiation.

  8. Broadening of CO2 lines in the 4.3 μm region by H2O (United States)

    Delahaye, T.; Landsheere, X.; Pangui, E.; Huet, F.; Hartmann, J.-M.; Tran, H.


    Transmission spectra of CO2 highly diluted in water vapor have been recorded at 50 and 95 °C for four pressures between 0.02 and 0.1 atm using a high resolution Fourier Transform spectrometer. The collisional (Lorentz) widths of many lines of the ν3 band (and of some of the ν3 + ν2 - ν2 hot band) have been retrieved from each spectrum through fits using Voigt line shapes. Our result are about 4% lower than the values recommended in a previous study but they confirm the relative variations of the line broadening on the rotational quantum numbers. We also provide the first determination of H2O-induced line shifts of CO2 lines.

  9. Auger Recombination in Self-Assembled Quantum Dots: Quenching and Broadening of the Charged Exciton Transition. (United States)

    Kurzmann, Annika; Ludwig, Arne; Wieck, Andreas D; Lorke, Axel; Geller, Martin


    In quantum dots (QDs), the Auger recombination is a nonradiative process in which the electron-hole recombination energy is transferred to an additional carrier. It has been studied mostly in colloidal QDs, where the Auger recombination time is in the picosecond range and efficiently quenches the light emission. In self-assembled QDs, on the other hand, the influence of Auger recombination on the optical properties is in general neglected, assuming that it is masked by other processes such as spin and charge fluctuations. Here, we use time-resolved resonance fluorescence to analyze the Auger recombination and its influence on the optical properties of a single self-assembled QD. From excitation-power-dependent measurements, we find a long Auger recombination time of about 500 ns and a quenching of the trion transition by about 80%. Furthermore, we observe a broadening of the trion transition line width by up to a factor of 2. With a model based on rate equations, we are able to identify the interplay between tunneling and Auger rate as the underlying mechanism for the reduced intensity and the broadening of the line width. This demonstrates that self-assembled QDs can serve as an ideal model system to study how the charge recapture process, given by the band-structure surrounding the confined carriers, influences the Auger process. Our findings are not only relevant for improving the emission properties of colloidal QD-based emitters and dyes, which have recently entered the consumer market, but also of interest for more visionary applications, such as quantum information technologies, based on self-assembled quantum dots.

  10. Density measurements using coherence imaging spectroscopy based on Stark broadening

    Energy Technology Data Exchange (ETDEWEB)

    Lischtschenko, O.; Bystrov, K.; De Temmerman, G. [Association EURATOM-FOM, FOM-Institute for Plasma Physics Rijnhuizen, partner in the Trilateral Euregio Cluster, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands); Howard, J. [Research Laboratory, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Jaspers, R. J. E. [Fusion Group, Eindhoven University of Technology, Postbus 513, 5600 MB Eindhoven (Netherlands); Koenig, R. [EURATOM Association, Max-Planck-Institut fuer Plasmaphysik, TI Greifswald, Wendelsteinstr.1, D-17491 Greifswald (Germany)


    A coherence imaging camera has been set up at Pilot-PSI. The system is to be used for imaging the plasma density through the Stark effect broadening of the H{sub {gamma}} line. Local density values are then obtained by the Abel inversion of the measured interferometric fringe contrast. This report will present the instrument setup and proof-of-principle demonstration. The inverted spatial electron density profiles obtained near the cascaded arc source of Pilot-PSI in discharges with axial magnetic field of B=0.4 T are compared with an independent measurement of electron density by Thomson scattering and good agreement is found.

  11. Deconvolution of Lorentzian broadened spectra. Pt. 1. Direct deconvolution

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, S.; Kantchev, K.


    A method is discussed of deconvolution of Lorentzian broadened experimental spectra directly in the ''time'' domain, that is, in the domain of the independent spectroscopic variable. The method consist in a numerical convolution of the spectrrum with a deconvoluting function which is calculated in conformity with a theoretical analysis of the sampled form of the input and output spectra and their Fourier transforms. An almost complete elimination of the systematic distortions and complete deconvolution degree are achieved. The restrictions imposed by the noise enhancement are estimated.

  12. Anomalous excitation facilitation in inhomogeneously broadened Rydberg gases

    CERN Document Server

    Letscher, Fabian; Niederprüm, Thomas; Ott, Herwig; Fleischhauer, Michael


    When atomic gases are laser driven to Rydberg states in an off resonant way, a single Rydberg atom may enhance the excitation rate of surrounding atoms. This leads to a facilitated excitation referred to as Rydberg anti-blockade. In the usual facilitation scenario, the detuning of the laser from resonance compensates the interaction shift. Here, we discuss a different excitation mechanism, which we call anomalous facilitation. This occurs on the "wrong side" of the resonance and originates from inhomogeneous broadening. The anomalous facilitation may be seen in experiments of attractively interacting atoms on the blue detuned side, where facilitation is not expected to appear.

  13. Strategies for broadening public involvement in space developments (United States)

    Harris, Philip R.


    There is widespread public interest in and goodwill toward the space program. For NASA's plans for the next 25 years to be achieved, this public reservoir of support needs to be tapped and channeled. NASA endeavors have to reach out beyond the scientific, technological, and aerospace communities to foster wider participation in space exploration and exploitation. To broaden NASA support and spread out the financing of space activities, recommendations for consideration are offered in the area of economics, political, institutional, international, and managerial areas.

  14. On the Stark Broadening of Lu III Spectral Lines

    Indian Academy of Sciences (India)

    Zlatko Majlinger; Zoran Simić; Milan S. Dimitrijević


    The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley.With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center – VAMDC.

  15. Corrigendum to "N2- and (H2+He)-broadened cross sections of benzene (C6H6) in the 7-15 μm region for the Titan and Jovian atmospheres" [Icarus, 271 (2016) 438-452 (United States)

    Sung, Keeyoon; Toon, Geoffrey C.; Crawford, Timothy J.


    We regret that there was a typographical error in the integrated band intensity of C6H6 in the abstract, in which the exponent was incorrectly given as 10-17 rather than 10-19. The integrated band intensities from N2-broadened C6H6 spectra quoted in the abstract should be 177.0(73), 14.0(10), 27.2(9) × 10-19 cm-1/(molecule · cm-2) for the v4, v14, v13 band regions, respectively. From (H2+He) mixture-broadened C6H6 spectra, the integrated v4 band intensity should be 168.8(17) × 10-19 cm-1/(molecule · cm-2). No other part of the manuscript was affected by this typographical error. We thank Conor A. Nixon for having brought this error to our attention.

  16. Effects of inhomogeneous broadening on the resonance Raman excitation profile of lycopene (United States)

    Cotting, J. E.; Hoskins, L. C.; Levan, M. E.


    The resonance Raman excitation profiles for the ν1, ν2, and ν3 vibrations of lycopene in ethyl alcohol, toluene, and carbon disulfide solvents have been measured. The results are interpreted in terms of a three-mode vibrational theory which includes both homogeneous and inhomogeneous broadening effects. Excellent agreement between calculated and observed excitation profiles and visible spectra was found, thus emphasizing the need to interpret resonance Raman data using a multimode vibrational model. The results indicate that the major broadening mechanism is homogeneous broadening, with about a 25% contribution from inhomogeneous broadening. The excitation profiles in carbon disulfide gave the largest inhomogeneous broadening.

  17. HYBASE : HYperspectral BAnd SElection

    NARCIS (Netherlands)

    Schwering, P.B.W.; Bekman, H.H.P.T.; Seijen, H.H. van


    Band selection is essential in the design of multispectral sensor systems. This paper describes the TNO hyperspectral band selection tool HYBASE. It calculates the optimum band positions given the number of bands and the width of the spectral bands. HYBASE is used to assess the minimum number of spe

  18. Spectrally selective optical pumping in Doppler-broadened cesium atoms

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun-Hai; Zeng Xian-Jin; Li Qing-Meng; Huang Qiang; Sun Wei-Min


    The D1 line spectrally selective pumping process in Doppler-broadened cesium is analyzed by solving the optical Bloch equations.The process,described by a three-level model with the A scheme,shows that the saturation intensity of broadened atoms is three orders of magnitude larger than that of resting atoms.The |Fg =3> → |Fe-4> resonance pumping can result in the ground state |Fg =4,mF =4> sublevel having a maximum population of 0.157 and the population difference would be about 0.01 in two adjacent magnetic sublevels of the hyperfine (HF) state Fg =4.To enhance the anisotropy in the ground state,we suggest employing dichromatic optical HF pumping by adding a laser to excite D1 line |Fg =4> → |Fe =3>transition,in which the cesium magnetometer sensitivity increases by half a magnitude and is unaffected by the nonlinear Zeeman effect even in Earth's average magnetic field.

  19. Rotational relaxation contributions to infrared pressure broadening in ozone (United States)

    Flannery, C.; Mizugai, Y.; Steinfeld, J. I.; Spencer, M. N.


    The time-resolved IR double-resonance spectroscopy apparatus and procedures described by Millot et al. (1988) are used to measure the relaxation times of rotational levels in the v3 =1 state of O3. Findings reported include (1) total rotational cross sections about 20-70 percent larger than the Lennard-Jones collision cross section, consistent with an interaction dominated by dipole-dipole forces; (2) equal relaxation cross sections in the upper and lower vibrational states; (3) an estimated pressure-broadening cross section of 185 sq A, with less than 10 percent due to dephasing; (4) no strong Ka dependence of rotational relaxation rates at Ka = 4-8 in J of about 16; (5) a rate for J = 8 and Ka = 7 about 40 percent larger than the other values measured, in agreement with the pressure-broadening model of Gamache and Rothman (1985); and (6) a V-V energy-transfer rate between v3 = 1 and v1 = 1 of (2.5 + or - 0.5) x 10 to the 6th/torr sec.

  20. Improving Program Design and Assessment with Broadening Participation Resources (United States)

    Siegfried, D.; Johnson, A.; Thomas, S. H.; Fauver, A.; Detrick, L.


    Many theoretical and research-based approaches suggest how to best use mentoring to enhance an undergraduate research program. The Institute for Broadening Participation's Pathways to Engineering and Pathways to Ocean Sciences projects synthesized a set of mentoring studies, theoretical sources, and other texts pertinent to undergraduate research program design into a suite of practical tools that includes an online mentoring manual, an online reference library of mentoring and diversity literature, and practical guides such as Using Social Media to Build Diversity in Your REU. The overall goal is to provide easy-to-access resources that can assist faculty and program directors in implementing or honing the mentoring elements in their research programs for undergraduates. IBP's Online Mentoring Manual addresses common themes, such as modeling, student self-efficacy, career development, retention and evaluation. The Online Diversity Reference Library provides a comprehensive, annotated selection of key policy documents, research studies, intervention studies, and other texts on broadening participation in science, technology, engineering and mathematics. IBP's suite of tools provides the theoretical underpinnings and research findings that can help leaders in education integrate site-appropriate mentoring elements into their educational programs. Program directors and faculty from a variety of program types and disciplines have benefitted from using the Manual and other resources. IBP continues the work of translating and synthesizing theory to practice and welcomes your participation and partnership in that effort.

  1. Broadening the diagnosis of bipolar disorder: benefits vs. risks (United States)



    There is considerable debate over whether bipolar and related disorders that share common signs and symptoms, but are currently defined as distinct clinical entities in DSM-IV and ICD-10, may be better characterized as falling within a more broadly defined “bipolar spectrum”. With a spectrum view in mind, the possibility of broadening the diagnosis of bipolar disorder has been proposed. This paper discusses some of the rationale for an expanded diagnostic scheme from both clinical and research perspectives in light of potential drawbacks. The ultimate goal of broadening the diagnosis of bipolar disorder is to help identify a common etiopathogenesis for these conditions to better guide treatment. To help achieve this goal, bipolar researchers have increasingly expanded their patient populations to identify objective biological or endophenotypic markers that transcend phenomenological observation. Although this approach has and will likely continue to produce beneficial results, the upcoming DSM-IV and ICD-10 revisions will place increasing scrutiny on psychiatry’s diagnostic classification systems and pressure to re-evaluate our conceptions of bipolar disorder. However, until research findings can provide consistent and converging evidence as to the validity of a broader diagnostic conception, clinical expansion to a dimensional bipolar spectrum should be considered with caution. PMID:21991268

  2. Multiple scattering and $p_t$-broadening at RHIC energies

    CERN Document Server

    Papp, G; Fái, G; Lévai, Peter; Zhang, Y


    In ultrarelativistic heavy-ion collisions, in the 2 GeV$broadening of the expected hadronic (e.g. pion) $p_\\perp$ spectra relative to proton-proton ($pp$) collisions. Thus, higher transverse-momentum regions are populated than in $pp$ collisions. In a perturbative QCD based calculation we include the intrinsic transverse momentum ($k_\\perp$) of the partons in the nucleon (determined from $pp$ collisions), augmented by the extra broadening obtained via a systematic analysis of proton-nucleus ($pA$) collisions in the energy range 17$<\\sqrt{s}<$ 39 AGeV. The original polynomial spectra are modified, and a nearly exponential spectrum appears in the region 2$\\lesssim p_\\perp\\lesssim 3.5$ GeV. At present RHIC energies ($\\sqrt{s}=$130 AGeV), the slope of the calculated spectra is reminiscent of that of fluid-dynamical descriptions, but lacks any thermal ori...

  3. Doppler broadening thermometry based on cavity ring-down spectroscopy

    CERN Document Server

    Cheng, C -F; Sun, Y R; Tan, Y; Kang, P; Hu, S -M


    A Doppler broadening thermometry (DBT) instrument is built based on cavity ring-down spectroscopy (CRDS) for precise determination of the Boltzmann constant. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach a satisfied precision at lower sample pressures, which also reduces the influence due to collisions. By recording the spectrum of C$_2$H$_2$ at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth values by several hours' measurement at a sample pressure of 1.5 Pa. The influence on the spectroscopy-determined temperatures has been investigated, including the "hidden" weak lines overlapped with the selected transition for DBT measurements. The reproducibility has also been examined to be better than 10 ppm, and it indicates that the instrument is feasible for DBT measurement toward a precision at the ppm level.

  4. E-cigarettes: a need to broaden the debate. (United States)

    Latif, E; Nair, M


    The unregulated market for e-cigarettes continues to grow, with debates on their efficacy and impact on global public health. E-cigarettes, or electronic nicotine delivery systems (ENDs), are marketed as a 'safe' alternative to tobacco products and a tool for 'harm reduction'. Some public health experts are calling it a 'game changer' and favour the 'harm reduction' strategy, while others dispute this claim. In our opinion, the debate needs to be broadened to encompass other related concerns and effects on non-users and affected stakeholders. As with tobacco control, a holistic approach is needed to build a raft of policies that effectively address the issue from all angles and look beyond the direct health implications of e-cigarette use to explore the social, economic, political and environmental aspects of this debate, putting 'harm reduction' in context.

  5. Brillouin resonance broadening due to structural variations in nanoscale waveguides

    CERN Document Server

    Wolff, Christian; Steel, Michael J; Eggleton, Benjamin J; Poulton, Christopher G


    We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the resonance width and shape of stimulated Brillouin scattering (SBS) in nanoscale waveguides. We find that they lead to an inhomogeneous resonance broadening through two distinct mechanisms: firstly, the acoustic frequency is directly influenced via mechanical nonlinearities; secondly, the optical wave numbers are influenced via the opto-mechanical nonlinearity leading to an additional acoustic frequency shift via the phase-matching condition. We find that this second mechanism is proportional to the opto-mechanical coupling and, hence, related to the SBS-gain itself. It is absent in intra-mode forward SBS, while it plays a significant role in backward scattering. In backward SBS increasing the opto-acoustic overlap beyond a threshold defined by the fabrication tolerances will therefore no longer yield the expected quadratic increase in overall Stokes amplification. Our results can be tra...

  6. Correlation function and electronic spectral line broadening in relativistic plasmas

    Directory of Open Access Journals (Sweden)

    Douis S.


    Full Text Available The electrons dynamics and the time autocorrelation function Cee(t for the total electric microfield of the electrons on positive charge impurity embedded in a plasma are considered when the relativistic dynamic of the electrons is taken into account. We have, at first, built the effective potential governing the electrons dynamics. This potential obeys a nonlinear integral equation that we have solved numerically. Regarding the electron broadening of the line in plasma, we have found that when the plasma parameters change, the amplitude of the collision operator changes in the same way as the time integral of Cee(t. The electron-impurity interaction is taken at first time as screened Deutsh interaction and at the second time as Kelbg interaction. Comparisons of all interesting quantities are made with respect to the previous interactions as well as between classical and relativistic dynamics of electrons.

  7. Positron annihilation Doppler broadening study of Xe-implanted aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yu, R.S., E-mail: [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Maekawa, M.; Kawasuso, A. [Japan Atomic Energy Agency, Advanced Science Research Center, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Wang, B.Y.; Wei, L. [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China)


    Positron annihilation Doppler broadening measurements were conducted to characterize information of defects in 380 keV Xe{sup +}-implanted aluminum upon thermal annealing at temperatures ranging from 100 to 600 °C. The results suggest a broad distribution in the depth of vacancy-type defects in all the as-implanted samples. Meanwhile, with an increase in implantation dose the defect-rich region shifts toward the sample surface. It was found that increasing the annealing temperature triggers surface-directed migration and coalescence of vacancy and Xe{sub n}V{sub m} clusters in samples with implantation doses of 1E15 and 1E16 Xe{sup +}cm{sup −2}. In the sample implanted with a high dose of 1E17 Xe{sup +}cm{sup −2}, positron annihilation revealed a decomposition and even elimination of such defects under post-implantation annealing treatment.

  8. Intrinsic homogeneous linewidth and broadening mechanisms of excitons in monolayer transition metal dichalcogenides

    KAUST Repository

    Moody, Galan


    The band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe2). The homogeneous linewidth is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton–exciton and exciton–phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here—strong many-body effects and intrinsically rapid radiative recombination—are expected to be ubiquitous in atomically thin semiconductors.

  9. Electrically-driven spectrally-broadened random lasing based on disordered photonic crystal structures (United States)

    Guo, X. J.; Wang, Y. F.; Jia, Y. F.; Zheng, W. H.


    We present the effect of radius randomness on the resonant spectrum and modal characteristics of a photonic crystal. With the introduction of randomness, different localizations were analyzed. The random pattern was then fabricated onto our lateral cavity surface emitting laser. Electrically driven random lasing was obtained with the localization and broadened spectrum, and the decrease of threshold and the increase of output power were also observed. The decreased threshold was due to the appearance of additional modes and the degree of localization. The output power reached a maximum with a random variance of 20 nm. It meant that there was a transition case in a regime ranging from Anderson localization to the local band edge resonance, and a balance between the Fabry-Perot-like effect and the random modulation effect. When the random variance reached 50 nm, the transition case in a regime ranging from localized to diffusive became remarkable. The experimental results are consistent with our theoretical analysis. One of the properties that make a random laser special with respect to regular lasers is its complex features in emission spectra, which means low spectral coherence. Our investigation on this kind of laser has referential and instructional significances for full-field imaging at visible wavelengths and other wavelengths.

  10. Spectral line broadening of Sr under the influence of collisions with foreign gas perturbers (United States)

    Makdisi, Y.


    The collision broadening of strontium Rydberg states under the influence of Xe, Ar and He gases has been studied by laser spectroscopy of two-photon excitation of Sr in a heat pipe. Broadening data for the 5s nd 1D 2 series are reported with buffer gas pressure in the range of 10 Torr to 500 Torr. Observed anomalies in broadening parameters due to inter-configuration perturbation are discussed.

  11. On the Stark broadening of Cr VI spectral lines in astrophysical plasma (United States)

    Dimitrijević, M. S.; Simić, Z.; Sahal-Bréchot, S.


    Stark broadening parameters for Cr VI lines have been calculated using semiclassical perturbation method for conditions of interest for stellar plasma. Here are presented, as an example of obtained results, Stark broadening parameters for electron- and proton-impact broadening for Cr VI 4s 2S-4p 2P° λ = 1430 Å and Cr VI 4p 2P°-5s 2S λ = 611.8 Å multiplets. The obtained results are used to demonstrate the importance of Stark broadening of Cr VI in DO white dwarf atmospheres. Also the obtained results will enter in STARK-B database which is included in Virtual Atomic and Molecula Data Center - VAMDC.

  12. Pressure broadening of NH3 by H2 from 15 to 40 K (United States)

    Willey, Daniel R.; Timlin, Robert E.; Deramo, Melinda; Pondillo, Peter L.; Wesolek, Danielle M.; Wig, Ryan W.


    Pressure broadening of the (J,K)=(1,1), (2,2), and (3,3) inversion transitions of NH3 was measured using normal- H2 as the broadening agent at kinetic temperatures of 15 to 40 K. Measurements were taken in a quasiequilibrium cell using the collisional cooling technique. H2 pressure broadening cross sections were compared to low-temperature He pressure broadening of the same transitions and found to be from 2.5 to 8 times larger than corresponding He cross sections. Measured normal- H2 and He cross sections were also compared to calculated J=0, para-H2 cross sections.

  13. Photoacoustic measurement of differential broadening of the Lambda doublets in NO(X 2Pi 1/2,v = 2-0) by Ar (United States)

    Pine, A. S.


    A differential broadening of the Lambda doublets in the v = 2-0 overtone band of the 2pi1/2 ground electronic state of NO in an Ar buffer gas has been observed by photoacoustic spectroscopy using a tunable color-center laser. The broadening coefficients for the f symmetry components are larger than for the e symmetry components by up to about 6 percent for J of about 16.5. This differential depends on J and vanishes at low J, implicating the anisotropy of the unpaired electron Pi orbital in the plane of rotation. The 2Pi3/2 transitions are slightly broader than the 2Pi1/2 as a result of spin-flipping collisional relaxation. The observed line shapes also exhibit collisional or Dicke narrowing due to velocity-changing collisions.

  14. High performance liquid chromatography column packings with deliberately broadened particle size distribution: relation between column performance and packing structure. (United States)

    Liekens, Anuschka; Billen, Jeroen; Sherant, Ron; Ritchie, Harald; Denayer, Joeri; Desmet, Gert


    The effect of the addition of 25%, 50% and 75% (weight percent, wt%) of larger particles (resp. 3 and 5 μm) to a commercial batch of 1.9 μm particles has been investigated as an academic exercise to study the effects of particle size distribution on the kinetic performance of packed bed columns in a magnified way. Comparing the performance of the different mixtures in a kinetic plot, it could be irrefutably shown that the addition of larger particles to a commercial batch of small particles cannot be expected to lead to an improved kinetic performance. Whereas the addition of 25 wt% of larger particles still only has a minor negative effect, a significantly deteriorated performance is obtained when 50 or 75 wt% of larger particles are added. In this case, separation impedance number increases up to 200% were observed. Studying the packing structure through computational packing simulations, together with the experimental determination of the external porosity, helped in understanding the obtained results. This showed that small particles tend to settle in the flow-through pores surrounding the larger particles, leading to very high packing densities (external porosities as low as 32% were observed) and also negatively influencing the column permeability as well as the band broadening (because of the broadened flow-through pore size range).

  15. Inhomogeneous linewidth broadening and radiative lifetime dispersion of size dependent direct bandgap radiation in Si quantum dot

    Directory of Open Access Journals (Sweden)

    Chung-Lun Wu


    Full Text Available The SiOx (SiOx:Si-QDs with buried Si quantum dots (Si-QDs is synthesized by plasma-enhanced chemical vapor deposition (PECVD, and the size-dependent wave-function of Si-QDs embedded in Si-rich SiO2 matrix is experimentally and theoretically analyzed to reformulate its bandgap energy as Eg(d = 1.12+5.83/d1.78. The photoluminescent lifetime of Si-QDs is dominated by the non-phonon assisted radiative recombination. Shrinking the Si-QD size from 4.3 to 1.9 nm increases the overlapping probability of electron-hole wave-functions in Si-QD to shorten the non-phonon assisted radiative lifetime from 6.3 μs to 83 ns. Fitting the time-resolved photoluminescence trace with a stretched exponential decay function reveals a lifetime dispersion factor. The lifetime dispersion greatly reduced from 0.8 to 0.39 by enlarging the size distribution of Si-QDs from 0.2 to 1.1 nm, which elucidates the inhomogeneous linewidth broadening feature of Si-QDs. Based on the simulation of non-phonon assisted recombination process, the full-band stretched exponential decay analysis confirms the correlation between inhomogeneous linewidth broadening and lifetime dispersion in Si-QDs.

  16. Broadening the Participation of Native Americans in Earth Science (United States)

    Bueno Watts, Nievita

    Climate change is not a thing of the future. Indigenous people are being affected by climate changes now. Native American Earth scientists could help Native communities deal with both climate change and environmental pollution issues, but are noticeably lacking in Earth Science degree programs. The Earth Sciences produce the lowest percentage of minority scientists when compared with other science and engineering fields. Twenty semi-structured interviews were gathered from American Indian/ Alaska Native Earth Scientists and program directors who work directly with Native students to broaden participation in the field. Data was analyzed using qualitative methods and constant comparison analysis. Barriers Native students faced in this field are discussed, as well as supports which go the furthest in assisting achievement of higher education goals. Program directors give insight into building pathways and programs to encourage Native student participation and success in Earth Science degree programs. Factors which impede obtaining a college degree include financial barriers, pressures from familial obligations, and health issues. Factors which impede the decision to study Earth Science include unfamiliarity with geoscience as a field of study and career choice, the uninviting nature of Earth Science as a profession, and curriculum that is irrelevant to the practical needs of Native communities or courses which are inaccessible geographically. Factors which impede progress that are embedded in Earth Science programs include educational preparation, academic information and counseling and the prevalence of a Western scientific perspective to the exclusion of all other perspectives. Intradepartmental relationships also pose barriers to the success of some students, particularly those who are non-traditional students (53%) or women (80%). Factors which support degree completion include financial assistance, mentors and mentoring, and research experiences. Earth scientists

  17. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M


    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  18. Evaluation of Pressure Stable Chip-to-Tube Fittings Enabling High-Speed Chip-HPLC with Mass Spectrometric Detection. (United States)

    Lotter, Carsten; Heiland, Josef J; Stein, Volkmar; Klimkait, Michael; Queisser, Marco; Belder, Detlev


    Appropriate chip-to-tube interfacing is an enabling technology for high-pressure and high-speed liquid chromatography on chip. For this purpose, various approaches, to connect pressure resistant glass chips with HPLC pumps working at pressures of up to 500 bar, were examined. Three side-port and one top-port connection approach were evaluated with regard to pressure stability and extra column band broadening. A clamp-based top-port approach enabled chip-HPLC-MS analysis of herbicides at the highest pressure and speed.

  19. Hyperfine structure effects in Doppler-broadening thermometry on water vapor at 1.4 μm (United States)

    Domenica De Vizia, Maria; Odintsova, Tatyana; Gianfrani, Livio


    This article builds upon a previous work dealing with the budget of uncertainties associated to our recent determination of the Boltzmann constant by means of Doppler broadening thermometry. We report on the outcomes of theoretical calculations and numerical simulations aimed to precisely quantify the influence of the unresolved hyperfine structure of a given ortho component of the \\text{H}218 O spectrum at 1.4 μm on the measurement of the Doppler width of the line itself. We have found that, if the hyperfine structure of the {{4}4,1}\\to {{4}4,0} line of the {ν1}+{ν3} band was ignored, the spectroscopic measurement of the Boltzmann constant would be affected by a relative systematical deviation of 4\\cdot {{10}-8} .

  20. Collisional broadening of alkali doublets by helium perturbers

    CERN Document Server

    Mullamphy, D F T; Peach, G; Venturi, V; Whittingham, I B


    We report results for the Lorentzian profiles of the Li I, Na I and K I doublets and the Na I subordinate doublet broadened by helium perturbers for temperatures up to 3000 K They have been obtained from a fully quantum-mechanical close-coupling description of the colliding atoms, the Baranger theory of line shapes and new ab initio potentials for the alkali-helium interaction. For all lines except the 769.9 nm K I line, the temperature dependence of the widths over the range 70 < T < 3000 K is accurately represented by the power law form w=aT^b with 0.37 < b < 0.43. The 769.9 K I line has this form for 500 < T < 3000 K with b = 0.49. Although the shifts have a more complex temperature dependence, they all have the general feature of increasing with temperature above T=500 K apart from the 769.9 K I line whose shift decreases with temperature.

  1. Momentum broadening in unstable quark-gluon plasma

    CERN Document Server

    Carrington, M E; Schenke, B


    Quark-gluon plasma produced at the early stage of ultrarelativistic heavy ion collisions is unstable, if weakly coupled, due to the anisotropy of its momentum distribution. Chromomagnetic fields are spontaneously generated and can reach magnitudes much exceeding typical values of the fields in equilibrated plasma. We consider a high energy test parton traversing an unstable plasma that is populated with strong fields. We study the momentum broadening parameter $\\hat q$ which determines the radiative energy loss of the test parton. We develop a formalism which gives $\\hat q$ as the solution of an initial value problem, and we focus on extremely oblate plasmas which are physically relevant for relativistic heavy ion collisions. The parameter $\\hat q$ is found to be strongly dependent on time. For short times it is of the order of the equilibrium value, but at later times $\\hat q$ grows exponentially due to the interaction of the test parton with unstable modes and becomes much bigger than the value in equilibri...

  2. Broadening Participation: Mentoring Community College Students in a Geoscience REU (United States)

    Smith, M.; Osborn, J.


    Increasingly, REUs are recruiting from community colleges as a means of broadening participation of underrepresented minorities, women, and low-income students in STEM. As inclusion of community college students becomes normalized, defining the role of science faculty and preparing them to serve as mentors to community college students is a key component of well-designed programs. This session will present empirical research regarding faculty mentoring in the first two years of an NSF-REU grant to support community college students in a university's earth and environmental science labs. Given the documented benefits of undergraduate research on students' integration into the scientific community and their career trajectory in STEM, the focus of the investigation has been on the processes and impact of mentoring community college STEM researchers at a university serving a more traditionally privileged population; the degree to which the mentoring relationships have addressed community college students needs including their emotional, cultural and resource needs; and gaps in mentor training and the mentoring relationship identified by mentors and students.

  3. Non-thermal line-broadening in solar prominence

    CERN Document Server

    Stellmacher, Goetz


    We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities. We have simultaneously observed a wide range of optically thin lines in quiescent prominences, selected for bright and narrow Mg\\,b emission without line satellites from macro-shifts. We find a ratio of reduced widths of H-gamma and H-delta of 1.05 +-0.03 which can hardly be attributed to saturation, since both are optically thin for the prominences observed: tau(gamma)<0.3 ; tau(delta)<0.15. We confirm the ratio of reduced widths of He4772(triplet) and He5015(singlet of 1.1 +-0.05 at higher significance and detect a width ratio of Mgb2 and Mg4571 (both from the triplet system) of 1.3 +-0.1. The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [T_kin ; V_nth]. Values of T_kin deduced from observed line radiance using models, indicate low temperatures down to T_kin~5000K. Non-thermal velocities, related to different physical states of...

  4. Study of Compton Broadening Due to Electron-Photon Scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.


    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  5. Workshops Without Walls: broadening access to science around the world.

    Directory of Open Access Journals (Sweden)

    Betül K Arslan


    Full Text Available The National Aeronautics and Space Administration (NASA Astrobiology Institute (NAI conducted two "Workshops Without Walls" during 2010 that enabled global scientific exchange--with no travel required. The second of these was on the topic "Molecular Paleontology and Resurrection: Rewinding the Tape of Life." Scientists from diverse disciplines and locations around the world were joined through an integrated suite of collaborative technologies to exchange information on the latest developments in this area of origin of life research. Through social media outlets and popular science blogs, participation in the workshop was broadened to include educators, science writers, and members of the general public. In total, over 560 people from 31 US states and 30 other nations were registered. Among the scientific disciplines represented were geochemistry, biochemistry, molecular biology and evolution, and microbial ecology. We present this workshop as a case study in how interdisciplinary collaborative research may be fostered, with substantial public engagement, without sustaining the deleterious environmental and economic impacts of travel.

  6. Quasiparticle band structure of antiferromagnetic Eu Te

    Energy Technology Data Exchange (ETDEWEB)

    Mathi Jaya, S.; Nolting, W. [Humboldt-Universitaet zu Berlin, Institut fuer Physik, Lehrstuhl Festkoerpertheorie, Invalidenstrasse 110, D-10115 Berlin (Germany)


    The temperature-dependent electronic quasiparticle spectrum of the antiferromagnetic semiconductor Eu Te is derived by use of a combination of a many-body model procedure with a tight-binding-'linear muffin tin orbital' (TB - LMTO) band structure calculation. The central part is the d-f model for a single band electron ('test electron') being exchange coupled to the anti ferromagnetically ordered localized moments of the Eu ions. The single-electron Bloch energies of the d-f model are taken from a TB-LMTO calculation for paramagnetic Eu Te. The d-f model is evaluated by a recently proposed moment conserving Green function technique to get the temperature-dependent sublattice-quasiparticle band structure (S-QBS) and sublattice-quasiparticle density of states (S-QDOS) of the unoccupied 5 d-6 s energy bands. Unconventional correlation effects and the appearance of characteristic quasiparticles ('magnetic polarons') are worked out in detail. The temperature dependence of the S-QDOS and S-QBS is mainly provoked by the spectral weights of the energy dispersions. Minority- and majority-spin spectra coincide for all temperatures but with different densities of states. Upon cooling from T{sub N} to T = 0 K the lower conduction band edge exhibits a small blue shift of -0.025 eV in accordance with the experiment. Quasiparticle damping manifesting itself in a temperature-dependent broadening of the spectral density peaks arises from spin exchange processes between (5 d-6 s) conduction band electrons and localized 4 f moments. (author)

  7. Power broadening effects on Electromagnetically Induced Transparency in $^{20}$Ne vapor

    CERN Document Server

    Lubotzky, Boaz; Kong, Tao; Katz, Nadav; Ron, Guy


    We report here the first observation of electromagnetically induced transparency (EIT) in $^{20}$Ne. The power broadening of the EIT linewidth is measured as a function of neon pressure and RF excitation power. Doppler effects on the EIT broadening are found even at low pressures and low intensities, where the linewidth should be governed only by homogeneous effects.

  8. New theoretical and experimental methods for pressure broadened linewidths and their interpretation (United States)

    Gelfand, J. J.


    A review of recent progress in the theory of collisional line broadening, particularly the impact of recent advances in collision dynamics calculations is presented. Some new approaches to the interpretation of experimentally measured linewidths and their impact on planetary atmosphere research are discussed. Experimental techniques which may have some advantage in providing pressure broadening data at very low temperatures are also mentioned.

  9. In vivo photoacoustic imaging of transverse blood flow using Doppler broadening of bandwidth


    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang


    A new method is proposed to measure transverse blood flow using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  10. In vivo photoacoustic imaging of transverse blood flow by using Doppler broadening of bandwidth


    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang


    A method is proposed to measure transverse blood flow by using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  11. Peak broadening in paper chromatography and related techniques : V. Conditions for minimum separation time

    NARCIS (Netherlands)

    Lygny, C.L. de; Kok, E.C.M.


    In paper and thin-layer chromatography peak broadening is a function of the mean flow rate of the eluent, which in turn is a function of the distances of the starting point and solvent front from the eluent in the tank. Starting from the relationship between peak broadening and the positions of sta

  12. Band parameters of phosphorene

    DEFF Research Database (Denmark)

    Lew Yan Voon, L. C.; Wang, J.; Zhang, Y.;


    Phosphorene is a two-dimensional nanomaterial with a direct band-gap at the Brillouin zone center. In this paper, we present a recently derived effective-mass theory of the band structure in the presence of strain and electric field, based upon group theory. Band parameters for this theory...

  13. Analysis of pulse broadening induced by the second-order PMD

    Institute of Scientific and Technical Information of China (English)

    Fu Song-Nian; Wu Chong-Qing; Shum Ping


    We propose a new conception of depolarization vector to describe the effect of depolarization induced by the second-order polarization mode dispersion (PMD). Deriving the formula of pulse broadening induced by the secondorder PMD, we find that the polarization-dependent chromatic dispersion (PCD) always enhances the pulse broadening.However the depolarization vector decreases the pulse broadening. The pulse broadening is correlated with the bit-rate of a transmission system. By adjusting the directions of the Stokes vector of initial state of polarization, initial firstorder polarization dispersion vector and depolarization vector to be parallel to each other, one can obtain an optimum dispersion compensation.But when the PCD is not equal to zero, the optimum dispersion cannot achieve a complete compensation, and the minimum pulse broadening is equal to σ = ( 2/4) (DCF/T0).

  14. Effect of Pressure Broadening on Molecular Absorption Cross Sections in Exoplanetary Atmospheres

    CERN Document Server

    Hedges, Christina


    Spectroscopic observations of exoplanets are leading to unprecedented constraints on their atmospheric compositions. However, molecular abundances derived from spectra are degenerate with the absorption cross sections which form critical input data in atmospheric models. Therefore, it is important to quantify the uncertainties in molecular cross sections to reliably estimate the uncertainties in derived molecular abundances. However, converting line lists into cross sections via line broadening involves a series of prescriptions for which the uncertainties are not well understood. We investigate and quantify the effects of various factors involved in line broadening in exoplanetary atmospheres - the profile evaluation width, pressure versus thermal broadening, broadening agent, spectral resolution, and completeness of broadening parameters - on molecular absorption cross sections. We use H$_2$O as a case study as it has the most complete absorption line data. For low resolution spectra (R$\\lesssim$100) for re...

  15. Low Power Band to Band Tunnel Transistors (United States)


    the E-field and tunneling at the source- pocket junction you form a parasitic NPN + transistor and the injection mechanism of carriers into the...hypothesis that the 1000 ° C, 5s anneal split lead to a very wide pocket and the accidental formation of a NPN + transistor , while the 1000 ° C, 1s anneal...Low Power Band to Band Tunnel Transistors Anupama Bowonder Electrical Engineering and Computer Sciences University of California at Berkeley

  16. Equivalence between the equilibrium dispersive and the transport model in describing band broadening in analytical gradient liquid chromatography. (United States)

    Hao, Weiqiang; Di, Bin; Yue, Bangyi; Chen, Qiang; Wu, Shun; Zhang, Peipei


    It is shown that the transport (TR) model may be equivalent to the equilibrium dispersive (ED) model in analytical gradient liquid chromatography when the column efficiency is not small. This result is obtained by assuming that the gradient profile is not distorted, the injection is an impulse, and the apparent axial dispersion coefficient (Da) of the ED model or the lumped kinetic coefficient (kfL) of the TR model varies with mobile phase composition. According to this equivalence, the plate height equation derived from the TR model in our previous work (Eq. (91) in Hao et al., 2013) is also suited for the ED model. This conclusion is confirmed by comparing the equation with the results obtained by Gritti and Guiochon from the ED model (Gritti and Guiochon, 2012). Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Broadening Undergraduate Research Skills With A New Astrophysics Laboratory Class (United States)

    Smecker-Hane, Tammy A.; Barth, A. J.


    To broaden the research skills of undergraduate students at the University of California, Irvine, we created a new required laboratory class called Observational Astrophysics, designed to be taken by junior and senior physics majors specializing in astrophysics. Students spend the first two weeks learning the basics of observational astronomy (coordinate systems, telescopes, CCDs, etc.) and completing homework assignments. Students spend the next eight weeks performing three lab experiments that involve: 1) CCD imaging of Jupiter with an 8-inch Meade telescope, doing astrometry of the their four brightest moons, and fitting the moons' distance versus time to derive the moons' orbital period, semimajor axis and inclination and Jupiter's mass, 2) CCD imaging of star cluster with a 24-inch telescope, doing profile-fitting photometry with DAOPHOT and doing main-sequence fitting of their observed color-magnitude diagram with stellar evolutionary models to derive the cluster's distance, reddening, and age, and 3) reducing longslit spectra of an x-ray binary previously taken with the Keck 10-meter telescope, deriving the radial velocity curve from cross-correlating the spectra with stellar templates, and deriving a lower limit on the mass of the black hole. In this paper, we discuss the course, report on the student reactions, and summarize some of the important things we learned in creating the class. Students enjoy the class. Although they find it difficult, they highly value the experience because they realize they are learning crucial research skills that will greatly help them when go on to do summer research, attend graduate school or work to industry. We are open to sharing our lab manual and data with others who wish to augment their university's curriculum.

  18. Cardiovascular RNA interference therapy: the broadening tool and target spectrum. (United States)

    Poller, Wolfgang; Tank, Juliane; Skurk, Carsten; Gast, Martina


    Understanding of the roles of noncoding RNAs (ncRNAs) within complex organisms has fundamentally changed. It is increasingly possible to use ncRNAs as diagnostic and therapeutic tools in medicine. Regarding disease pathogenesis, it has become evident that confinement to the analysis of protein-coding regions of the human genome is insufficient because ncRNA variants have been associated with important human diseases. Thus, inclusion of noncoding genomic elements in pathogenetic studies and their consideration as therapeutic targets is warranted. We consider aspects of the evolutionary and discovery history of ncRNAs, as far as they are relevant for the identification and selection of ncRNAs with likely therapeutic potential. Novel therapeutic strategies are based on ncRNAs, and we discuss here RNA interference as a highly versatile tool for gene silencing. RNA interference-mediating RNAs are small, but only parts of a far larger spectrum encompassing ncRNAs up to many kilobasepairs in size. We discuss therapeutic options in cardiovascular medicine offered by ncRNAs and key issues to be solved before clinical translation. Convergence of multiple technical advances is highlighted as a prerequisite for the translational progress achieved in recent years. Regarding safety, we review properties of RNA therapeutics, which may immunologically distinguish them from their endogenous counterparts, all of which underwent sophisticated evolutionary adaptation to specific biological contexts. Although our understanding of the noncoding human genome is only fragmentary to date, it is already feasible to develop RNA interference against a rapidly broadening spectrum of therapeutic targets and to translate this to the clinical setting under certain restrictions.

  19. Multiwavelength Raman fiber ring laser with the spectrum profile broadened by parametric four wave mixing in highly nonlinear dispersion-shifted fibers

    Institute of Scientific and Technical Information of China (English)

    Yan Wang; Qing Wang; Wei Zhang; Xiaoming Liu; Jiangde Peng


    @@ A broadband multiwavelength Raman fiber ring laser (RFRL) covering the whole C-band at room temperature are presented. The effect of the intracavity highly nonlinear dispersion-shifted fiber on broadening and flattening the output spectrum envelope is discussed and experimentally demonstrated. More than 45-dB extinction-ratio multiwavelength output from 1527.76 to 1566.86 nm with 100-GHz channel spacing and 2.1-dB power ripple has been achieved by carefully controlling the individual powers of three pump lasers.

  20. Collision-induced line parameters for the (2 ← 0) overtone band of HCl (1.76 μm) in binary mixtures with H2 and CH4 (United States)

    Domanskaya, Alexandra V.; Li, Gang; Tran, Ha; Gisi, Michael; Ebert, Volker


    We present experimental results on pressure broadening and shift coefficients in the first vibrational overtone band of HCl in gaseous mixtures with H2 and CH4 at room temperature. The whole set of collisional parameters for HCl-CH4 is novel. Most of the data for HCl-H2 system is also published for the first time. Our results have a precision of about 2% or better for shifts and below 1% for broadening in the band center.

  1. Broadening the Frequency Bandwidth of Piezoelectric Energy Harvesters Using Coupled Linear Resonators (United States)

    Sadeqi, Soheil

    The desire to reduce power consumption of current integrated circuits has led design engineers to focus on harvesting energy from free ambient sources such as vibrations. The energy harvested this way can eliminate the need for battery replacement, particularly, in low-energy remote sensing and wireless devices. Currently, most vibration-based energy harvesters are designed as linear resonators, therefore, they have a narrow resonance frequency. The optimal performance of such harvesters is achieved only when their resonance frequency is matched with the ambient excitation. In practice, however, a slight shift of the excitation frequency will cause a dramatic reduction in their performance. In the majority of cases, the ambient vibrations are totally random with their energy distributed over a wide frequency spectrum. Thus, developing techniques to extend the bandwidth of vibration-based energy harvesters has become an important field of research in energy harvesting systems. This thesis first reviews the broadband vibration-based energy harvesting techniques currently known in some detail with regard to their merits and applicability under different circumstances. After that, the design, fabrication, modeling and characterization of three new piezoelectric-based energy harvesting mechanism, built typically for rotary motion applications, is discussed. A step-by-step procedure is followed in order to broaden the bandwidth of such energy harvesters by introducing a coupled spring-mass system attached to a PZT beam undergoing rotary motion. It is shown that the new strategies can indeed give rise to a wide-band frequency response making it possible to fine-tune their dynamical response. The numerical results are shown to be in good agreement with the experimental data as far as the frequency response is concerned.

  2. Magneto-induced Line Broadening of Magneto-sensitive Lines in Solar Magnetized Atmospheres

    Institute of Scientific and Technical Information of China (English)

    Zhong-Quan Qu; Shuai Wang; Cheng-Lin Xu; Xiao-Yu Zhang; Ming-Guo Sun; Chun-Lan Jin


    We analyze the spectral line broadening of those magneto-sensitive lines in solar magnetized atmospheres. The broadening at the line wings is due to the increase of the effective width of energy levels involved in Zeeman splitting,and the broadening at the line core also originated in Zeeman splitting under the condition that the Zeeman components are mixed. Therefore, the magnetoinduced or Zeeman broadening take effects on the whole line. The observed Stokes parameter data in a sunspot and outside it acquired by Solar Stokes Spectrum Telescope (S3T) are analyzed for the demonstration of this mechanism, and the Zeeman broadening rates are calculated for FeI 6302.5 under some assumptions.Our result shows that the broadening is increased as the magnetic field strength becomes stronger, but the rate of increase at the line core is decreased as the field strength increases, while the rate at the wing does not show such an obvious regularity. The broadening is more effective in the line core than in the wings.

  3. Rabi Oscillations in Realistic Superlattice with Finite Bloch Bands

    Institute of Scientific and Technical Information of China (English)

    FAN Wen-Bin; ZHANG Ping; LUO Ying; ZHAO Xian-Geng


    We investigate the dynamical processes taking place in nanodevices by high-frequency dc-ac fields. We found that Rabi oscillations between minibands are clearly identified under theoretical resonant conditions derived by an ideal two-band superlattice model, the resonant conditions have broadened, and the amount of broadening is about four times of the Rabi oscillation frequency. We also want to elucidate the role of different mechanisms that could lead to loss of quantum coherence. Our results show how the dephasing effects of disorder of interface roughness and doping fluctuation that after some periods destroy coherent oscillations, such as Rabi oscillations,can be reduced dramatically if we apply a bias static electric field to the superlattice system. The doping fluctuation dephasing effect is much stronger than that of interface roughness in the coherent process of realistic superlattices.

  4. Consequences and mechanisms of spike broadening of R20 cells in Aplysia californica. (United States)

    Ma, M; Koester, J


    We studied frequency-dependent spike broadening in the two electrically coupled R20 neurons in the abdominal ganglion of Aplysia. The peptidergic R20 cells excite the R25/L25 interneurons (which trigger respiratory pumping) and inhibit the RB cells. When fired at 1-10 Hz, the duration of the falling phase of the action potential in R20 neurons increases 2-10 fold during a spike train. Spike broadening recorded from the somata of the R20 cells affected synaptic transmission to nearby follower cells. Chemically mediated synaptic output was reduced by approximately 50% when recorded trains of nonbroadened action potentials were used as command signals for a voltage-clamped R20 cell. Electrotonic EPSPs between the R20 cells, which normally facilitated by two- to fourfold during a high frequency spike train, showed no facilitation when spike broadening was prevented under voltage-clamp control. To examine the mechanism of frequency-dependent spike broadening, we applied two-electrode voltage-clamp and pharmacological techniques to the somata of R20 cells. Several voltage-gated ionic currents were isolated, including INa, a multicomponent ICa, and three K+ currents--a high threshold, fast transient A-type K+ current (IAdepol), a delayed rectifier K+ current (IK-V), and a Ca(2+)-sensitive K+ current (IK-Ca), made up of two components. The influences of different currents on spike broadening were determined by using the recorded train of gradually broadening action potentials as the command for the voltage clamp. We found the following. (1) IAdepol is the major outward current that contributes to repolarization of nonbroadened spikes. It undergoes pronounced cumulative inactivation that is a critical determinant of spike broadening. (2) Activity-dependent changes in IK-V, IK-Ca, and ICa have complex effects on the kinetics and extent of broadening. (3) The time integral of ICa during individual action potentials increases approximately threefold during spike broadening.

  5. Unfolding the band structure of non-crystalline photonic band gap materials. (United States)

    Tsitrin, Samuel; Williamson, Eric Paul; Amoah, Timothy; Nahal, Geev; Chan, Ho Leung; Florescu, Marian; Man, Weining


    Non-crystalline photonic band gap (PBG) materials have received increasing attention, and sizeable PBGs have been reported in quasi-crystalline structures and, more recently, in disordered structures. Band structure calculations for periodic structures produce accurate dispersion relations, which determine group velocities, dispersion, density of states and iso-frequency surfaces, and are used to predict a wide-range of optical phenomena including light propagation, excited-state decay rates, temporal broadening or compression of ultrashort pulses and complex refraction phenomena. However, band calculations for non-periodic structures employ large super-cells of hundreds to thousands building blocks, and provide little useful information other than the PBG central frequency and width. Using stereolithography, we construct cm-scale disordered PBG materials and perform microwave transmission measurements, as well as finite-difference time-domain (FDTD) simulations. The photonic dispersion relations are reconstructed from the measured and simulated phase data. Our results demonstrate the existence of sizeable PBGs in these disordered structures and provide detailed information of the effective band diagrams, dispersion relation, iso-frequency contours, and their angular dependence. Slow light phenomena are also observed in these structures near gap frequencies. This study introduces a powerful tool to investigate photonic properties of non-crystalline structures and provides important effective dispersion information, otherwise difficult to obtain.

  6. Pressure broadening calculations for OH in collisions with argon: Rotational, vibrational, and electronic transitions (United States)

    Dagdigian, Paul J.


    Collisional parameters describing both the pressure-induced broadening and shifting of isolated lines in the spectrum of the hydroxyl radical in collisions with argon have been determined through quantum scattering calculations using accurate potential energy surfaces describing the OH(X2 Π , A2Σ+)-Ar interactions. These calculations have been carried for pure rotational, vibrational, and electronic transitions. The calculated pressure broadening coefficients are in good agreement with the available measurements in the microwave, infrared, and ultraviolet spectral regions. Computed pressure broadening coefficients as a function of temperature are reported for these three types of transitions.

  7. Computing the inhomogeneous broadening of electronic transitions in solution: a first-principle quantum mechanical approach. (United States)

    Avila Ferrer, Francisco José; Improta, Roberto; Santoro, Fabrizio; Barone, Vincenzo


    Starting from Marcus's relationship connecting the inhomogeneous broadening with the solvent reorganization energy and exploiting recent state-specific developments in PCM/TD-DFT calculations, we propose a procedure to estimate the polar broadening of optical transitions. When applied to two representative molecular probes, coumarin C153 and 4-aminophthalimide, in different solvents, our approach provides for the polar broadening values fully consistent with the experimental ones. Thanks to these achievements, for the first time fully ab initio vibrationally resolved absorption spectra in solution are computed, obtaining spectra for coumarin C153 in remarkable agreement with experiments.

  8. Influence of Doppler-broadening on absorption-dispersion properties in a resonant coherent medium

    Institute of Scientific and Technical Information of China (English)

    Xu Wei-Hua; Gao Jin-Yue


    We investigate the influence of Doppler broadening on absorption-dispersion properties in a four-level atomic system that can evolve from a normal dispersion to an anomalous dispersion. Our results show that the absorption-dispersion properties become strongly dependent on the propagation directions of the applied fields if Doppler broadening is taken into account. Especially, the switchover in the sign of the dispersion is still achievable even in the presence of Doppler broadening if properly arranging the propagation directions of the applied fields, which is in contrast with the otherwise behaviours in some other configurations.

  9. Polycyclic Aromatic Hydrocarbons and the Diffuse Interstellar Bands: a Survey (United States)

    Salama, F.; Galazutdinov, G. A.; Krelowski, J.; Allamandola, L. J.; Musaev, F. A.; DeVincenzi, Donald L. (Technical Monitor)


    We discuss the proposal relating the origin of some of the diffuse interstellar bands (DIBs) to neutral and ionized polycyclic aromatic hydrocarbons (PAHs) present in interstellar clouds. Laboratory spectra of several PAHs, isolated at low temperature in inert gas matrices, are compared with an extensive set of astronomical spectra of reddened, early type stars. From this comparison, it is concluded that PAN ions are good candidates to explain some of the DIBs. Unambiguous assignments are difficult, however, due to the shift in wavelengths and the band broadening induced in the laboratory spectra by the solid matrix. Definitive band assignments and, ultimately, the test of the of the proposal that PAH ions carry some of the DIB must await the availability of gas-phase measurements in the laboratory. The present assessment offers a guideline for future laboratory experiments by allowing the preselection of promising PAH molecules to be studied in jet expansions.

  10. A unified numerical model of collisional depolarization and broadening rates due to hydrogen atom collisions

    CERN Document Server

    Derouich, M; Barklem, P S


    Interpretation of solar polarization spectra accounting for partial or complete frequency redistribution requires data on various collisional processes. Data for depolarization and polarization transfer are needed but often missing, while data for collisional broadening are usually more readily available. Recent work by Sahal-Br\\'echot and Bommier concluded that despite underlying similarities in the physics of collisional broadening and depolarization processes, relationships between them are not possible to derive purely analytically. We aim to derive accurate numerical relationships between the collisional broadening rates and the collisional depolarization and polarization transfer rates due to hydrogen atom collisions. Such relationships would enable accurate and efficient estimation of collisional data for solar applications. Using earlier results for broadening and depolarization processes based on general (i.e. not specific to a given atom), semi-classical calculations employing interaction potentials...

  11. Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines (United States)

    Shindo, F.; Zhu, C.; Kirby, K.; Babb, J. F.


    We are carrying out a joint theoretical and experimental research program to study the broadening of alkali atom resonance lines due to collisions with helium and molecular hydrogen for applications to spectroscopic studies of brown dwarfs and extrasolar giant planets.

  12. Single photon quantum non-demolition in the presence of inhomogeneous broadening


    Greentree, Andrew D.; Beausoleil, R. G.; Hollenberg, L. C. L.; Munro, W. J.; Nemoto, Kae; Prawer, S.; Spiller, T. P.


    Electromagnetically induced transparency (EIT) has been often proposed for generating nonlinear optical effects at the single photon level; in particular, as a means to effect a quantum non-demolition measurement of a single photon field. Previous treatments have usually considered homogeneously broadened samples, but realisations in any medium will have to contend with inhomogeneous broadening. Here we reappraise an earlier scheme [Munro \\textit{et al.} Phys. Rev. A \\textbf{71}, 033819 (2005...

  13. Evolution of shear banding flows in metallic glasses characterized by molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Li, E-mail: [Shanghai Institute of Space Power-Sources, 2965 Dongchuan Rd., Shanghai 200245 (China); Luan, Yingwei [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai 200240 (China)


    To reveal the evolution of shear banding flows, one-dimensional nanostructure metallic glass composites have been studied with molecular dynamics. The inherent size determines the initial thickness of shear bands, and the subsequent broadening can be restricted to some extent. The vortex-like flows evoke the atomic motion perpendicular to the shear plane, which accelerates the interatomic diffusion. The reduction of local strain rate causes the flow softening for monolithic Cu-Zr glass, but the participation of Cu-atoms in the shear banding flow gradually leads to the shear hardening for the composites.

  14. Stretch Band Exercise Program (United States)

    Skirka, Nicholas; Hume, Donald


    This article discusses how to use stretch bands for improving total body fitness and quality of life. A stretch band exercise program offers a versatile and inexpensive option to motivate participants to exercise. The authors suggest practical exercises that can be used in physical education to improve or maintain muscular strength and endurance,…


    NARCIS (Netherlands)



    Banding techniques were carried out on metaphase chromosomes of zebrafish (Danio rerio) embryos. The karyotypes with the longest chromosomes consist of 12 metacentrics, 26 submetacentrics, and 12 subtelocentrics (2n = 50). All centromeres are C-band positive. Eight chromosomes have a pericentric C-b

  16. Envelope broadening and scattering attenuation of a scalar wavelet in random media having power-law spectra (United States)

    Sato, Haruo


    Peak delay and envelope broadening of an S-wavelet with travel distance increasing are seen in short-period seismograms of small earthquakes. Those phenomena are results of scattering by random velocity inhomogeneities in the earth medium. As shown in sonic well-log data we may suppose that random velocity fluctuation has power-law spectra even in the seismic spectral range. As a simple mathematical model, we study how the envelope of a scalar wavelet varies in von Kármán-type random media, which have power-law spectra at large wavenumbers. Since the centre wavenumber of a wavelet is a unique scale in the power-law spectral range, using it as a reference, we divide the random media into the low-wavenumber spectral (long-scale) component and the high-wavenumber spectral (short-scale) component. For the wave propagation through the long-scale component of random media, we may apply the parabolic approximation to the wave equation. Using the Markov approximation, which is a stochastic extension of the phase screen method, we directly synthesize the energy density, which is the mean-square (MS) envelope of a wavelet in a given frequency band. The envelope duration increases according to the second power of travel distance. There is an additional factor, the wandering effect which increases the envelope duration according to the traveltime fluctuation. Wide angle scattering caused by the short-scale component of random media attenuates wave amplitude with travel distance increasing. We use the total scattering coefficient of the short-scale component as a measure of scattering attenuation per distance, which is well described by the Born approximation. Multiplying the exponential scattering attenuation factor by the MS envelope derived by the Markov approximation, we can synthesize the MS envelope reflecting all the spectral components of random media. When the random medium power spectra have a steep role-off at large wavenumbers, the envelope broadening is small and

  17. Measurements of NH3 linestrengths and collisional broadening coefficients in N2, O2, CO2, and H2O near 1103.46cm-1

    KAUST Repository

    Owen, Kyle


    Laser-based ammonia gas sensors have useful applications in many fields including combustion, atmospheric monitoring, and medical diagnostics. Calibration-free trace gas sensors require the spectroscopic parameters including linestrengths and collisional broadening coefficients to be known. Ammonia\\'s strong ν2 vibrational band between 9 - 12 μm has the high absorption strength needed for sensing small concentrations. Within this band, the 1103.46cm-1 feature is one of the strongest and has minimal interference from CO2 and H2O. However, the six rotational transitions that make up this feature have not been studied previously with absorption spectroscopy due to their small line spacing ranging from 0.004 to 0.029cm-1. A tunable quantum cascade laser was used to accurately study these six transitions. A retrieval program was used to determine the linestrengths and collisional broadening coefficients based on Voigt and Galatry profiles. The experiments were performed with ammonia mixtures in nitrogen, oxygen, water vapor, and carbon dioxide at room temperature in an optical cell. These data are going to aid in the development of quantitative ammonia sensors utilizing this strong absorption feature. © 2013 Elsevier Ltd.

  18. Semi-classical H2-broadening coefficients of 12CH3D rovibrational lines and their temperature dependence for planetary atmosphere modeling (United States)

    Sinyakova, T.; Buldyreva, J.


    Theoretical hydrogen-broadening coefficients and associated temperature exponents for 12CH3D (J, K) lines in parallel (ΔK = 0) bands are calculated by a semi-classical approach based on a rigorous consideration of the active molecule as a symmetric top, a model intermolecular potential comprising both short- and long-range interactions, and exact classical trajectories. The leading potential terms are shown to provide a realistic description of line broadening in comparison with scarce measurements available in the literature. The calculations performed for 296, 240 and 190 K are used to extract the line-width temperature-dependence exponents for the typical temperature range of atmospheric interest ∼200-300 K. Detailed P-Q-R-line lists are provided for large intervals of quantum numbers (0 ≤ J ≤ 20, 0 ≤ K ≤ J) requested for remote sensing of planetary atmospheres, in particular those of outer planets and their moons. With negligible vibrational dependence of CH3D line-widths and estimated as negligible their sub-branch dependence, these data can be also employed for perpendicular bands.

  19. Progressive Band Selection (United States)

    Fisher, Kevin; Chang, Chein-I


    Progressive band selection (PBS) reduces spectral redundancy without significant loss of information, thereby reducing hyperspectral image data volume and processing time. Used onboard a spacecraft, it can also reduce image downlink time. PBS prioritizes an image's spectral bands according to priority scores that measure their significance to a specific application. Then it uses one of three methods to select an appropriate number of the most useful bands. Key challenges for PBS include selecting an appropriate criterion to generate band priority scores, and determining how many bands should be retained in the reduced image. The image's Virtual Dimensionality (VD), once computed, is a reasonable estimate of the latter. We describe the major design details of PBS and test PBS in a land classification experiment.

  20. Line broadening in the PXRD patterns of layered hydroxides: The relative effects of crystallite size and structural disorder

    Indian Academy of Sciences (India)

    Grace S Thomas; P Vishnu Kamath


    Layered hydroxides crystallize in a hexagonal structure and incorporate a number of different types of structural disorders as an exigency of anisotropic bonding. Structural disorder contributes to the non-uniform broadening of lines in the powder X-ray diffraction pattern. Common among the disorders are stacking faults, which broaden the ℎ0ℓ/0ℓ reflections. Interstratification selectively broadens the 00ℓ reflections and turbostratic disorder broadens the 0ℓ reflections. The line broadening caused by structural disorder has to be discounted before estimates of particle size are made by applying the Scherrer formula.

  1. Ground- and excited-state impurity bands in quantum wells (United States)

    Ghazali, A.; Gold, A.; Serre, J.


    The density of states and the spectral density of electrons in quantum wells with charged impurities are calculated with use of a multiple-scattering method. The impurity-density-dependent broadening and the gradual merging of the ground (1s) and excited (2p+/-,2s) impurity levels into impurity bands are investigated. At low density the shapes of the 1s, 2p+/-, and 2s spectral densities are found to be in excellent agreement with the analytical results obtained for the ideal two-dimensional Coulomb problem.

  2. Iliotibial band friction syndrome. (United States)

    Lavine, Ronald


    Published articles on iliotibial band friction syndrome have been reviewed. These articles cover the epidemiology, etiology, anatomy, pathology, prevention, and treatment of the condition. This article describes (1) the various etiological models that have been proposed to explain iliotibial band friction syndrome; (2) some of the imaging methods, research studies, and clinical experiences that support or call into question these various models; (3) commonly proposed treatment methods for iliotibial band friction syndrome; and (4) the rationale behind these methods and the clinical outcome studies that support their efficacy.

  3. CRYSIZ: a program for computing crystallite size and strain from the broadening of powder diffraction lines

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, C.R. [Oak Ridge National Lab., TN (United States); Morosin, B. [Sandia National Labs., Albuquerque, NM (United States); Stewart, J.M. [Maryland Univ., College Park, MD (United States)


    The program CRYSIZ is designed to take the powder diffraction line profiles for a well-crystallized sample, called a reference pattern, and for a sample of the same substance, called a broadened pattern, to produce measures of the mean crystallite size, the distribution of crystallite sizes, and the root mean square residual microstrain in the broadened sample. The data required are the two powder patterns and a series of directives to signal the calculations and plots to be done during the execution of the program. The program loads files containing the background corrected powder diffraction intensity data for both the reference and broadened patterns. Preliminary calculations find the centroids, full width at half maximums, integral breadths, spans over sum, and second moments. Two methods of deconvoluting the profile to calculate size and strain are allowed. Either the direct or the Stokes Fourier coefficient method of deconvolution may be chosen. In the direct method the profiles are extracted by numerical fitting. This method is slower but produces unfolded profiles free of ringing and the ``hook effect``. In this case the Fourier coefficients required for Warren-Averbach analysis are produced from the deconvoluted profile. In the Stokes method the diffraction pattern of each reference and broadened profile is Fourier transformed to produce a set of Fourier coefficients. The Fourier coefficients of the broadened profiles are divided by those of the reference pattern. The resulting coefficients are the Stokes coefficients. The Stokes coefficients are smoothed by a least- squares procedure in order to remove noise and quell ringing and hooking, then used as input to a reverse Fourier transform. This transform produces an ``unfolded powder line,`` which is a best estimate of the broadened profile with the reference profile and noise removed. The deconvolution of the reference profile gives a broadened profile due only to the crystallite size and strain.

  4. Diet after gastric banding (United States)

    ... helps people who have a gastric band stay satisfied longer. This includes things like salad with grilled ... ADAM Health Solutions. About MedlinePlus Site Map FAQs Customer Support Get email updates Subscribe to RSS Follow ...

  5. HYBASE - HYperspectral BAnd SElection tool

    NARCIS (Netherlands)

    Schwering, P.B.W.; Bekman, H.H.P.T.; Seijen, H.H. van


    Band selection is essential in the design of multispectral sensor systems. This paper describes the TNO hyperspectral band selection tool HYBASE. It calculates the optimum band positions given the number of bands and the width of the spectral bands. HYBASE is used to calculate the minimum number of

  6. Differential effects of K(+) channel blockers on frequency-dependent action potential broadening in supraoptic neurons. (United States)

    Hlubek, M D; Cobbett, P


    Recordings were made from magnocellular neuroendocrine cells dissociated from the supraoptic nucleus of the adult guinea pig to determine the role of voltage gated K(+) channels in controlling the duration of action potentials and in mediating frequency-dependent action potential broadening exhibited by these neurons. The K(+) channel blockers charybdotoxin (ChTx), tetraethylammonium (TEA), and 4-aminopyridine (4-AP) increased the duration of individual action potentials indicating that multiple types of K(+) channel are important in controlling action potential duration. The effect of these K(+) channel blockers was almost completely reversed by simultaneous blockade of voltage gated Ca(2+) channels with Cd(2+). Frequency-dependent action potential broadening was exhibited by these neurons during trains of action potentials elicited by membrane depolarizing current pulses presented at 10 Hz but not at 1 Hz. 4-AP but not ChTx or TEA inhibited frequency-dependent action potential broadening indicating that frequency-dependent action potential broadening is dependent on increasing steady-state inactivation of A-type K(+) channels (which are blocked by 4-AP). A model of differential contributions of voltage gated K(+) channels and voltage gated Ca(2+) channels to frequency-dependent action potential broadening, in which an increase of Ca(2+) current during each successive action potential is permitted as a result of the increasing steady-state inactivation of A-type K(+) channels, is presented.

  7. Mechanism of frequency-dependent broadening of molluscan neurone soma spikes. (United States)

    Aldrich, R W; Getting, P A; Thompson, S H


    1. Action potentials recorded from isolated dorid neurone somata increase in duration, i.e. broaden, during low frequency repetitive firing. Spike broadening is substantially reduced by external Co ions and implicates an inward Ca current. 2. During repetitive voltage clamp steps at frequencies slower than 1 Hz, in 100 mM-tetraethyl ammonium ions (TEA) inward Ca currents do not increase in amplitude. 3. Repetitive action potentials result in inactivation of delayed outward current. Likewise, repetitive voltage clamp steps which cause inactivation of delayed outward current also result in longer duration action potentials. 4. The frequency dependence of spike broadening and inactivation of the voltage dependent component (IK) of delayed outward current are similar. 5. Inactivation of IK is observed in all cells, however, only cells with relative large inward Ca currents show significant spike broadening. Spike broadening apparently results from the frequency dependent inactivation of IK which increases the expression of inward Ca current as a prominent shoulder on the repolarizing phase of the action potential. In addition, the presence of a prolonged Ca current increases the duration of the first action potential thereby allowing sufficient time for inactivation of IK.

  8. Numerical analysis to four-wave mixing induced spectral broadening in high power fiber lasers (United States)

    Feng, Yujun; Wang, Xiaojun; Ke, Weiwei; Sun, Yinhong; Zhang, Kai; Ma, Yi; Li, Tenglong; Wang, Yanshan; Wu, Juan


    For powers exceeding a threshold the spectral broadening in fiber amplifiers becomes a significant challenge for the development of high power narrow bandwidth fiber lasers. In this letter, we show that the spectral broadening can be partly caused by four-wave mixing(FWM) process in which the power of the central wavelength would transfer to the side ones. A practical FWM induced spectral broadening theory has been derived from the early works. A numerical model of fiber amplifier has been established and FWM process has been added to the model. During the simulation process, we find that when a 10 GHz, several watts narrow bandwidth laser is seeded into a few modes fiber laser amplifier, the FWM induced spectral broadening effect might continually increase the FWHM of the spectra of the continuum laser to 100 GHz within the amplification process to several hundred watts which has been convinced by our experiments. Some other results have also been analyzed in this paper to complete the four-wave mixing induced spectral broadening theory in fiber amplifiers.

  9. Line parameters including temperature dependences of self- and air-broadened line shapes of 12C16O2: 1.6-μm region (United States)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.


    Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured

  10. Observation of asymmetric spectrum broadening induced by silver nanoparticles in a heavy-metal oxide glass

    CERN Document Server

    Zhavoronkov, N; Bregadiolli, B A; Nalin, M; Malomed, B A


    We demonstrate experimentally and support by a theoretical analysis an effect of asymmetric spectrum broadening, which results from doping of silver nanoparticles into a heavy-glass matrix, 90(0.5WO3-0.3SbPO4-0.2PbO)-10AgCl. The strong dispersion of the effective nonlinear coefficient of the composite significantly influences the spectral broadening via the self-phase modulation, and leads to a blue upshift of the spectrum. Further extension of the spectrum towards shorter wavelengths is suppressed by a growing loss caused by the plasmon resonance in the silver particles. The red-edge spectral broadening is dominated by the stimulated Raman Scattering.

  11. Dielectric spectra broadening as the signature of dipole-matrix interaction. I. Water in nonionic solutions. (United States)

    Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ishai, Paul Ben; Feldman, Yuri


    Whenever water interacts with another dipolar entity, a broadening of its dielectric relaxation occurs. Often this broadening can be described by the Cole-Cole (CC) spectral function. A new phenomenological approach has been recently presented [A. Puzenko, P. Ben Ishai, and Y. Feldman, Phys. Rev. Lett. 105, 037601 (2010)] that illustrates a physical mechanism of the dipole-matrix interaction underlying the CC behavior in complex systems. By considering the relaxation amplitude Δε, the relaxation time τ, and the broadening parameter α, one can construct a set of 3D trajectories, representing the dynamic behavior of different systems under diverse conditions. Our hypothesis is that these trajectories will contribute to a deeper understanding of the dielectric properties of complex systems. The paper demonstrates how the model describes the state of water in aqueous solutions of non-ionic solutes. For this purpose complex dielectric spectra for aqueous solutions of D-glucose and D-fructose are analyzed.

  12. Coronal turbulence and the angular broadening of radio sources - the role of the structure function

    CERN Document Server

    Ingale, M; Cairns, Iver


    The amplitude of density turbulence in the extended solar corona, especially near the dissipation scale, impinges on several problems of current interest. Radio sources observed through the turbulent solar wind are broadened due to refraction by and scattering off density inhomogeneities, and observations of scatter broadening are often employed to constrain the turbulence amplitude. The extent of such scatter broadening is usually computed using the structure function, which gives a measure of the spatial correlation measured by an interferometer. Most such treatments have employed analytical approximations to the structure function that are valid in the asymptotic limits $s \\gg l_{i}$ or $s \\ll l_{i}$, where $s$ is the interferometer spacing and $l_{i}$ is the inner scale of the density turbulence spectrum. We instead use a general structure function (GSF) that straddles these regimes, and quantify the errors introduced by the use of these approximations. We have included the effects of anisotropic scatteri...

  13. Curriculum of broaden education and theory of teaching activity in school Physical Education

    Directory of Open Access Journals (Sweden)

    Sirléia Silvano


    Full Text Available This paper focuses on the conception of curriculum with broaden character in Physical Education and Davidov and Leontiev’s learning theory as possibility of focusing on human education in the omnilateral perspective. We endorse the necessity that the curriculum dynamics – dealing with knowledge, school systematization and standardization of school practices – becomes effective in a curriculum of broaden character. We consider that dealing with knowledge involves the necessity to create conditions that promote the transmission and assimilation of school knowledge. We refer therefore to a scientific direction of the teaching process, in other words, that the teacher leads the student to enter into study activity; from abstract knowledge rising to concrete theoretical knowledge, which is brought about by curriculum organization from a broaden conception.

  14. Shift and broadening of resonance lines of antiprotonic helium atoms in solid helium

    CERN Document Server

    Adamczak, Andrzej


    We have estimated the shift and broadening of the resonance lines in the spectrum of antiprotonic helium atoms $\\bar{p}\\mathrm{He}^{+}$ implanted in solid helium $^4$He. The application of the response function for crystalline helium has enabled determination of the contributions from the collective degrees of freedom to the shift and broadening. It occurs that the broadening due to the collective motion is negligible compared to the natural line width. The available pair-correlation functions for crystalline $^4$He have been applied for estimating the resonance-line shift due to collisions of $\\bar{p}\\mathrm{He}^{+}$ atom with the surrounding $^4$He atoms. The dependence of the line shift, which has been calculated in the quasistatic limit, on the solid-$^4$He density is nonlinear.

  15. Self-referencing of an on-chip soliton Kerr frequency comb without external broadening

    CERN Document Server

    Brasch, Victor; Jost, John D; Geiselmann, Michael; Kippenberg, Tobias J


    Self-referencing turns pulsed laser systems into self-referenced frequency combs. Such frequency combs allow counting of optical frequencies and have a wide range of applications. The required optical bandwidth to implement self-referencing is typically obtained via nonlinear broadening in optical fibers. Recent advances in the field of Kerr frequency combs have provided a path towards the development of compact frequency comb sources that provide broadband frequency combs, exhibit microwave repetition rates and that are compatible with on-chip photonic integration. These devices have the potential to significantly expand the use of frequency combs. Yet to date self-referencing of such Kerr frequency combs has only been attained by applying conventional, fiber based broadening techniques. Here we demonstrate external broadening-free self-referencing of a Kerr frequency comb. An optical spectrum that spans two-thirds of an octave is directly synthesized from a continuous wave laser-driven silicon nitride micro...

  16. A meta-analysis of the magnetic line broadening in the solar atmosphere

    CERN Document Server

    Ramos, A Asensio


    A multi-line Bayesian analysis of the Zeeman broadening in the solar atmosphere is presented. A hierarchical probabilistic model, based on the simple but realistic Milne-Eddington approximation to the solution of the radiative transfer equation, is used to explain the data in the optical and near infrared. Our method makes use of the full line profiles of a more than 500 spectral lines from 4000 $\\AA$ to 1.8 $\\mu$m. Although the problem suffers from a strong degeneracy between the magnetic broadening and any other remaining broadening mechanism, the hierarchical model allows to isolate the magnetic contribution with reliability. We obtain the cumulative distribution function for the field strength and use it to put reliable upper limits to the unresolved magnetic field strength in the solar atmosphere. The field is below 160-180 G with 90% probability.

  17. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD$^+$ ions

    CERN Document Server

    Patra, Sayan


    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD$^+$), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel \\textit{et al.} \\cite{Biesheuvel2016} presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel \\textit{et al.} to theoretically study the Doppler-broadened hyperfine structure of the $(v,L):(0,3)\\rightarrow(4,2)$ rovibrational transition in HD$^+$ at 1442~nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine compo...

  18. Gamma-ray emission spectrum from thermonuclear fusion reactions without intrinsic broadening

    DEFF Research Database (Denmark)

    Nocente, M.; Källne, J.; Salewski, Mirko


    First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution instrume......First principle calculations of the gamma-ray energy spectrum arising from thermonuclear reactions without intrinsic broadening in fusion plasmas are presented, extending the theoretical framework needed to interpret measurements up to the accuracy level enabled by modern high resolution...... information that can be extracted from the gamma-ray emission spectrum of fusion reactions without intrinsic broadening and are of relevance for applications to high performance plasmas of present and next generation devices....

  19. Photonic band gap materials (United States)

    Cassagne, D.

    Photonic band gap materials Photonic band gap materials are periodic dielectric structures that control the propagation of electromagnetic waves. We describe the plane wave method, which allows to calculate the band structures of photonic crystals. By symmetry analysis and a perturbative approach, we predict the appearance of the low energy photonic band gaps of hexagonal structures. We propose new two-dimensional structures called graphite and boron nitride. Using a transfer matrix method, we calculate the transmission of the graphite structure and we show the crucial role of the coupling with external modes. We study the appearance of allowed modes in the photonic band gap by the introduction of localized defects in the periodicity. Finally, we discuss the properties of opals formed by self-organized silica microspheres, which are very promising for the fabrication of three-dimensional photonic crystals. Les matériaux à bandes interdites photoniques sont des structures diélectriques périodiques qui contrôlent la propagation des ondes électromagnétiques. Nous décrivons la méthode des ondes planes qui permet de calculer les structures de bandes des cristaux photoniques. Par une analyse de la symétrie et une approche perturbative, nous précisons les conditions d'existence des bandes interdites de basse énergie. Nous proposons de nouvelles structures bidimensionnelles appelées graphite et nitrure de bore. Grâce à une méthode de matrices de transfert, nous calculons la transmission de la structure graphite et nous mettons en évidence le rôle fondamental du couplage avec les modes extérieurs. Nous étudions l'apparition de modes permis dans la bande interdite grâce à l'introduction de défauts dans la périodicité. Enfin, nous discutons les propriétés des opales constituées de micro-billes de silice auto-organisées, qui sont très prometteuses pour la fabrication de cristaux photoniques tridimensionnels.

  20. Band bending and electrical transport at chemically modified silicon surfaces (United States)

    Lopinski, Greg; Ward, Tim; Hul'Ko, Oleksa; Boukherroub, Rabah


    High resolution electron energy loss spectroscopy (HREELS) and electrical transport measurements have been used to investigate how various chemical modifications give rise to band bending and alter the conductivity of Si(111) surfaces. HREELS is a sensitive probe of band bending through observations of the low frequency free carrier plasmon mode. For hydrogen terminated surfaces, prepared by the standard etch in ammonium flouride, HREELS measurements on both n and n+ substrates are consistent with nearly flat bands. Chlorination of these surfaces results in substantial upward band bending due to the strong electron withdrawing nature of the chlorine, driving the surface into inversion. The presence of this inversion layer on high resistivity n-type samples is observed through a substantial enhancement of the surface conductivity (relative to the H-terminated surface), as well as through broadening of the quasi-elastic peak in the HREELS measurements. We have also begun to examine organically modified silicon surfaces, prepared by various wet chemical reactions with the H-terminated surface. Decyl modified Si(111) surfaces are seen to exhibit a small degree of band bending, attributed to extrinsic defect states cause by a small degree of oxidation accompanying the modification reaction. The prospects of using conductivity as an in-situ monitor of the rate of these reactions will be discussed.

  1. Pressure broadening of atomic oxygen two-photon absorption laser induced fluorescence (United States)

    Marinov, Daniil; Drag, Cyril; Blondel, Christophe; Guaitella, Olivier; Golda, Judith; Klarenaar, Bart; Engeln, Richard; Schulz-von der Gathen, Volker; Booth, Jean-Paul


    Atomic oxygen, considered to be a determining reactant in plasma applications at ambient pressure, is routinely detected by two-photon absorption laser induced fluorescence (TALIF). Here, pressure broadening of the (2p 4 3 P 2  →  3p 3 P J=0,1,2) two-photon transition in oxygen atoms was investigated using a high-resolution TALIF technique in normal and Doppler-free configurations. The pressure broadening coefficients determined were {γ{{\\text{O}2}}}   =  0.40  ±  0.08  cm-1/bar for oxygen molecules and {γ\\text{He}}   =  0.46  ±  0.03 cm-1/bar for helium atoms. These correspond to pressure broadening rate constants k\\text{PB}{{\\text{O}2}}   =  9 · 10-9 cm3 s-1 and k\\text{PB}\\text{He}   =  4 · 10-9 cm3 s-1, respectively. The well-known quenching rate constants of O(3p 3 P J ) by O2 and He are at least one order of magnitude smaller, which signifies that non-quenching collisions constitute the main line-broadening mechanism. In addition to providing new insights into collisional processes of oxygen atoms in electronically excited 3p 3 P J state, reported pressure broadening parameters are important for quantification of oxygen TALIF line profiles when both collisional and Doppler broadening mechanisms are important. Thus, the Doppler component (and hence the temperature of oxygen atoms) can be accurately determined from high resolution TALIF measurements in a broad range of conditions.

  2. Spectral signatures of x((5)) processes in four-wave mixing of homogeneously broadened excitons

    DEFF Research Database (Denmark)

    Langbein, W.; Meier, T.; Koch, S.W.;


    The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton-biexcito...... of one- and two-exciton resonances up to the fifth order in the optical field.......The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton...

  3. Linear Broadening of the Confining String in Yang-Mills Theory at Low Temperature

    CERN Document Server

    Gliozzi, F; Wiese, U -J


    The logarithmic broadening predicted by the systematic low-energy effective field theory for the confining string has recently been verified in numerical simulations of (2+1)-d SU(2) lattice Yang-Mills theory at zero temperature. The same effective theory predicts linear broadening of the string at low non-zero temperature. In this paper, we verify this prediction by comparison with very precise Monte Carlo data. The comparison involves no additional adjustable parameters, because the low-energy constants of the effective theory have already been fixed at zero temperature. It yields very good agreement between the underlying Yang-Mills theory and the effective string theory.

  4. Laser-Induced Optical Breakdown in Methane: Diagnostic Using H-Gamma Line Broadening

    Directory of Open Access Journals (Sweden)

    Christian G. Parigger


    Full Text Available Measurements and analysis are reported of Stark-broadened profiles of the H-gamma line emitted from plasma formed by Laser-Induced Optical Breakdown (LIOB in a pulsed methane flow. Electron densities Ne are deduced for 18 instants of time in the range between 0.4 and 2.1 microseconds after LIOB and for 2 different gas pressures. The obtained values of Ne are in a good agreement with the corresponding values found previously from Stark-broadened profiles of the H-alpha and H-beta lines.

  5. The density broadening in a sodium F=2 condensate detected by a pulse train

    Directory of Open Access Journals (Sweden)

    Jianing Han


    Full Text Available The dipole-blockaded sodium clock transition has been detected by high resolution microwave spectroscopy, the multiple-pulse spectroscopy. This spectroscopic technique has been first used to detect the density broadening and shifting in a Sodium Bose Einstein Condensate (BEC by probing the sodium clock-transition. Moreover, by narrowing the pulse-width of the pulses, some of the broadening mechanisms can be partially reduced. The results reported here are essential steps toward the ground-state quantum computing, few-body spectroscopy, spin squeezing and quantum metrology.

  6. Initial characterization of an Experimental Referee Broadened-Specification (ERBS) aviation turbine fuel (United States)

    Prok, G. M.; Seng, G. T.


    Characterization data and a hydrocarbon compositional analysis are presented for a research test fuel designated as an experimental referee broadened-specification aviation turbine fuel. This research fuel, which is a special blend of kerosene and hydrotreated catalytic gas oil, is a hypothetical representation of a future fuel should it become necessary to broaden current kerojet specifications. It is used as a reference fuel in research investigations into the effects of fuel property variations on the performance and durability of jet aircraft components, including combustors and fuel systems.

  7. Effect of PMD-induced Pulse Broadening on Sensitivity and Frequency Spectrum

    Institute of Scientific and Technical Information of China (English)


    The PMD-induced pulse broadening may cause the degradation of receiver sensitivity and has negative effects on the power spectrum of received signals. The expressions of PMD-induced pulse broadening effects on receiver sensitivity are derived based on the concept of mean square pulse width. The effects of PMD on the spectrum of received power are analyzed in detail. Finally, the scheme is discussed with which the power of a certain frequency component is extracted as a feedback control signal in a PMD compensation system.

  8. How two-dimensional brick layer J-aggregates differ from linear ones: excitonic properties and line broadening mechanisms

    CERN Document Server

    Dijkstra, Arend G; Knoester, Jasper; Nelson, Keith A; Cao, Jianshu


    We study the excitonic coupling and homogeneous spectral line width of brick layer J-aggregate films. We begin by analysing the structural information revealed by the two-exciton states probed in two-dimensional spectra. Our first main result is that the relation between the excitonic couplings and the spectral shift in a two-dimensional structure is different (larger shift for the same nearest neighbour coupling) from that in a one-dimensional structure, which leads to an estimation of dipolar coupling in two-dimensional lattices. We next investigate the mechanisms of homogeneous broadening - population relaxation and pure dephasing - and evaluate their relative importance in linear and two-dimensional aggregates. Our second main result is that pure dephasing dominates the line width in two-dimensional systems up to a crossover temperature, which explains the linear temperature dependence of the homogeneous line width. This is directly related to the decreased density of states at the band edge when compared...

  9. Distribution Free Prediction Bands

    CERN Document Server

    Lei, Jing


    We study distribution free, nonparametric prediction bands with a special focus on their finite sample behavior. First we investigate and develop different notions of finite sample coverage guarantees. Then we give a new prediction band estimator by combining the idea of "conformal prediction" (Vovk et al. 2009) with nonparametric conditional density estimation. The proposed estimator, called COPS (Conformal Optimized Prediction Set), always has finite sample guarantee in a stronger sense than the original conformal prediction estimator. Under regularity conditions the estimator converges to an oracle band at a minimax optimal rate. A fast approximation algorithm and a data driven method for selecting the bandwidth are developed. The method is illustrated first in simulated data. Then, an application shows that the proposed method gives desirable prediction intervals in an automatic way, as compared to the classical linear regression modeling.

  10. Ka-band and X-band observations of the solar corona acquired during the Cassini 2001 superior conjunction (United States)

    Morabito, D. D.


    Simultaneous dual-frequency Ka-band (32 GHz) and X-band (8.4 GHz) carrier signal data have been acquired during the superior conjunction of the Cassini spacecraft June 2001, using the NASA Deep Space Network's facilities located in Goldstone, California. The solar elongation angle of the observations varied from -4.1 degrees (-16 solar radii) to -0.6 degrees (-2.3 solar radii). The observed coronal and solar effects on the signals include spectral broadening, amplitude scintillation, phase scintillation, and increased noise. The measurements were generally consistent with existing solar models, except during solar transient events when the signatures of the measurements were observed to increase significantly above the quiet background levels. This is the second solar conjunction of Cassini for which simultaneous X/Ka data were acquired. Both solar conjunctions, conducted in May 2000 and June 2001, occurred near the peak of the current 11 year solar cycle.

  11. Ultra wide band antennas

    CERN Document Server

    Begaud, Xavier


    Ultra Wide Band Technology (UWB) has reached a level of maturity that allows us to offer wireless links with either high or low data rates. These wireless links are frequently associated with a location capability for which ultimate accuracy varies with the inverse of the frequency bandwidth. Using time or frequency domain waveforms, they are currently the subject of international standards facilitating their commercial implementation. Drawing up a complete state of the art, Ultra Wide Band Antennas is aimed at students, engineers and researchers and presents a summary of internationally recog

  12. Banded transformer cores (United States)

    Mclyman, C. W. T. (Inventor)


    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  13. Valence band energy spectrum of HgTe quantum wells with an inverted band structure (United States)

    Minkov, G. M.; Aleshkin, V. Ya.; Rut, O. E.; Sherstobitov, A. A.; Germanenko, A. V.; Dvoretski, S. A.; Mikhailov, N. N.


    The energy spectrum of the valence band in HgTe /CdxHg1 -xTe quantum wells of a width (8 -20 ) nm has been studied experimentally by magnetotransport effects and theoretically in the framework of a four-band k P method. Comparison of the Hall density with the density found from a period of the Shubnikov-de Haas (SdH) oscillations clearly shows that the degeneracy of states of the top of the valence band is equal to 2 at the hole density p top of the valence band consists of four spin-degenerate extremes located at k ≠0 (valleys) which gives the total degeneracy K =8 . It is shown that taking into account the "mixing of states" at the interfaces leads to the removal of the spin degeneracy that reduces the degeneracy to K =4 . Accounting for any additional asymmetry, for example, due to the difference in the mixing parameters at the interfaces, the different broadening of the boundaries of the well, etc., leads to reduction of the valleys degeneracy, making K =2 . It is noteworthy that for our case twofold degeneracy occurs due to degeneracy of two single-spin valleys. The hole effective mass (mh) determined from analysis of the temperature dependence of the amplitude of the SdH oscillations shows that mh is equal to (0.25 ±0.02 ) m0 and weakly increases with the hole density. Such a value of mh and its dependence on the hole density are in a good agreement with the calculated effective mass.

  14. Exceptionally large banded spherulites (United States)

    Lagasse, R. R.


    This article concerns the crystallization of maleic anhydride from a blend containing 2 wt% of poly(acrylonitrile). High speed photography and temperature measurements during the crystallization as well as X-ray diffraction from the blend after crystallization are consistent with a banded spherulitic morphology.

  15. Colloquium: Topological band theory (United States)

    Bansil, A.; Lin, Hsin; Das, Tanmoy


    The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. This review begins by discussing underpinnings of the topological band theory, which involve a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder and interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary, and quaternary compounds, transition metal and f -electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites, and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultrathin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. This Colloquium concludes by giving a perspective on research directions where further work will broadly benefit the topological materials field.


    Directory of Open Access Journals (Sweden)

    P. Jithu


    Full Text Available The WLAN and Bluetooth applications become popular in mobile devices, integrating GSM and ISM bands operation in one compact antenna, can reduce the size of mobile devices. Recently, lot many investigations are carried out in designing a dual band antennas with operating frequencies in GSM band and in ISM band for mobile devices. Printed monopoles are under this investigation. In this paper, dual-band printed monopoles are presented to operate at GSM band i.e. 900 MHz and ISM band i.e. 2.4 GHz. We intend to observe the antenna characteristics on the network analyzer and verify the theoretical results with the practical ones.

  17. Spectral broadening of acoustic tones generated by unmanned aerial vehicles in a turbulent atmosphere

    DEFF Research Database (Denmark)

    Ostashev, Vladimir E.; Wilson, D. K.; Finn, Anthony


    The acoustic spectrum emitted by unmanned aerial vehicles (UAVs) and other aircraft can be distorted by propagation through atmospheric turbulence. Since most UAVs are propeller-based, they generate a series of acoustic tones and harmonics. In this paper, spectral broadening of these tones due...

  18. Electromagnetically-induced-transparency intensity-correlation power broadening in a buffer gas (United States)

    Zheng, Aojie; Green, Alaina; Crescimanno, Michael; O'Leary, Shannon


    Electromagnetically-induced-transparency (EIT) noise correlation spectroscopy holds promise as a simple, robust method for performing high-resolution spectroscopy used in optical magnetometry and clocks. Of relevance to these applications, we report on the role of buffer gas pressure and magnetic field gradients on power broadening of Zeeman-EIT noise correlation resonances.

  19. Reducing the impact of inhomogeneous broadening on quantum dot based electromagnetically induced transparency

    DEFF Research Database (Denmark)

    Hansen, Per Lunnemann; Mørk, Jesper


    Slow light based on electromagnetically induced transparency in an inhomogeneously broadened quantum dot medium is investigated theoretically. Three schemes, , V, and Λ, are compared and it is shown that the V-scheme gives a group velocity that is more than three orders of magnitude smaller...

  20. High-energy pulse compressor using self-defocusing spectral broadening in anomalously dispersive media

    DEFF Research Database (Denmark)

    Bache, Morten; Zhou, Binbin


    A new high-energy pulse compressor uses self-defocusing spectral broadening in anomalously dispersive quadratic nonlinear crystals, followed by positive group-delay-dispersion compensation. Compression to sub-50 fs is possible from Joule-class 1.03 µm femtosecond amplifiers in large-aperture KDP....

  1. Observation of Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay

    CERN Document Server

    Schwartz, S B; Bennett, M B; Liddick, S N; Perez-Loureiro, D; Bowe, A; Chen, A A; Chipps, K A; Cooper, N; Irvine, D; McNeice, E; Montes, F; Naqvi, F; Ortez, R; Pain, S D; Pereira, J; Prokop, C; Quaglia, J; Quinn, S J; Sakstrup, J; Santia, M; Shanab, S; Simon, A; Spyrou, A; Thiagalingam, E


    Background: The Doppler broadening of $\\gamma$-ray peaks due to nuclear recoil from $\\beta$-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using $\\beta$-delayed proton emission or applied to a recoil heavier than $A=10$. Purpose: To test and apply this Doppler broadening method using $\\gamma$-ray peaks from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Methods: A fast beam of $^{26}$P was implanted into a planar Ge detector, which was used as a $^{26}$P $\\beta$-decay trigger. The SeGA array of high-purity Ge detectors was used to detect $\\gamma$ rays from the $^{26}$P($\\beta p\\gamma$)$^{25}$Al decay sequence. Results: Radiative Doppler broadening in $\\beta$-delayed proton-$\\gamma$ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV $\\gamma$-ray line for which the proton energies were previously known. The 1776 keV $\\gamma$ ray de-exciting the 2720 keV $^{25}$Al level was observed...

  2. On quantum-mechanical unified theories of collisional spectral line broadening

    NARCIS (Netherlands)

    Schuller, F.; Nienhuis, G.


    We compare the Baranger-type unified theory of line broadening with a quantum version of the binary-collision approach. For the simple model system of a two-state atom, where both treatments are well-defined, the binary-collision theory results only from the exact formalism after an inversion of an

  3. Kramers-Kronig relation in a Doppler-broadenedΛ-type three-level system

    Institute of Scientific and Technical Information of China (English)

    王梦; 庞兆广; 王如泉; 左战春; 芦小刚; 白金海; 裴丽娅; 缪兴绪; 高艳磊; 吴令安; 傅盘铭; 杨世平


    We measure the absorption and dispersion in a Doppler-broadenedΛ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers–Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations.

  4. Foreign gas broadening and shift of the strongly ``forbidden'' lead line at 1278.9nm (United States)

    Horvatic, Vlasta; Veza, Damir; Movre, Mladen; Niemax, Kay; Vadla, Cedomil


    The collisional broadening and shift rate coefficients of the "forbidden" 6p 2 3P 0 → 6p 2 3P 1 transition in lead were determined by diode laser absorption measurements performed simultaneously in two resistively heated hot-pipes. One hot-pipe contained Pb vapor and noble gas (Ar or He) at low pressure, while the other was filled with Pb and noble gas at variable pressure. The measurements were performed at temperatures of 1220 K and 1290 K, i.e., lead number densities of 4.8 × 10 15 cm - 3 and 1.2 × 10 16 cm - 3 . The broadening rates were obtained by fitting the experimental collisionally broadened absorption line shapes to theoretical Voigt profiles. The shift rates were determined by measuring the difference between the peak absorption positions in the spectra measured simultaneously in the heat pipe filled with noble gas at reference pressure and the one with noble gas at variable pressure. The following data for the broadening and shift rate coefficients due to collisions with Ar and He were obtained: γBAr = (3.4 ± 0.1) × 10 - 10 cm 3 s - 1 , γBHe = (3.8 ± 0.1) × 10 - 10 cm 3 s - 1 , γSAr = (- 7.3 ± 0.8) × 10 - 11 cm 3 s - 1 , γSHe = (- 6.5 ± 0.7) × 10 - 11 cm 3 s - 1 .

  5. Quantum Memory for Microwave Photons in an Inhomogeneously Broadened Spin Ensemble

    DEFF Research Database (Denmark)

    Julsgaard, Brian; Grezes, Cécile; Bertet, Patrice


    We propose a multi-mode quantum memory protocol able to store the quantum state of the field in a microwave resonator into an ensemble of electronic spins. The stored information is protected against inhomogeneous broadening of the spin ensemble by spin-echo techniques resulting in memory times o...

  6. Spectrally resolved four-wave mixing in semiconductors: Influence of inhomogeneous broadening

    DEFF Research Database (Denmark)

    Erland, J.; Pantke, K.-H.; Mizeikis, V.


    We study the influence of inhomogeneous broadening on results obtained from spectrally resolved transient four-wave mixing. In particular, we study the case where more resonances are coherently excited, leading to polarization interference or quantum beats, depending on the microscopic nature...

  7. Broaden Engineering Technology students' knowledge through hands-on with motion robotics (United States)

    The skills and knowledge that employers value most are not always well-aligned with undergraduate engineering technology programs. With the support of a federal grant, we identify and propose to broaden the undergraduate student experience to include training in transferable skills with agricultura...

  8. Origins of spectral broadening of incoherent waves: Catastrophic process of coherence degradation (United States)

    Xu, G.; Garnier, J.; Rumpf, B.; Fusaro, A.; Suret, P.; Randoux, S.; Kudlinski, A.; Millot, G.; Picozzi, A.


    We revisit the mechanisms underlying the process of spectral broadening of incoherent optical waves propagating in nonlinear media on the basis of nonequilibrium thermodynamic considerations. A simple analysis reveals that a prerequisite for the existence of a significant spectral broadening of the waves is that the linear part of the energy (Hamiltonian) has different contributions of opposite signs. It turns out that, at variance with the expected soliton turbulence scenario, an increase of the amount of disorder (incoherence) in the system does not require the generation of a coherent soliton structure. We illustrate the idea by considering the propagation of two wave components in an optical fiber with opposite dispersion coefficients. A wave turbulence approach to the problem reveals that the increase of kinetic energy in one component is offset by the negative reduction in the other component, so that the waves exhibit, as a general rule, virtually unlimited spectral broadening. More precisely, a self-similar solution of the kinetic equations reveals that the spectra of the incoherent waves tend to relax toward a homogeneous distribution in the wake of a front that propagates in frequency space with a decelerating velocity. We discuss this catastrophic process of spectral broadening in the light of different important phenomena, in particular supercontinuum generation, soliton turbulence, wave condensation, and the runaway motion of mechanical systems composed of positive and negative masses.


    Energy Technology Data Exchange (ETDEWEB)

    Spitler, L. G.; Lee, K. J.; Eatough, R. P.; Kramer, M.; Karuppusamy, R.; Desvignes, G.; Champion, D. J.; Falcke, H. [Max-Planck-Institut für Radioastronomie, Bonn D-53121 (Germany); Bassa, C. G.; Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, M13, 9PL Manchester (United Kingdom); Cognard, I. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace LPC2E CNRS-Université d' Orléans, F-45071 Orléans Cedex 02, and Station de radioastronomie de Nançay, Observatoire de Paris, CNRS/INSU, F-18330 Nançay (France); Bower, G. C. [UC Berkeley Astronomy Department, B-20 Hearst Field Annex, Berkeley, CA 94720-3411 (United States); Cordes, J. M. [Department of Astronomy and Space Sciences, Cornell University, Ithaca, NY 14853 (United States)


    We present temporal scattering measurements of single pulses and average profiles of PSR J1745-2900, a magnetar recently discovered only 3 arcsec away from Sagittarius A* (Sgr A*), from 1.2 to 18.95 GHz using the Effelsberg 100 m Radio Telescope, the Nançay Decimetric Radio Telescope, and the Jodrell Bank Lovell Telescope. Single pulse analysis shows that the integrated pulse profile above 2 GHz is dominated by pulse jitter, while below 2 GHz the pulse profile shape is dominated by scattering. This is the first object in the Galactic center (GC) with both pulse broadening and angular broadening measurements. We measure a pulse broadening time scale at 1 GHz of τ{sub 1GHz} = 1.3 ± 0.2 and pulse broadening spectral index of α = –3.8 ± 0.2, which is several orders of magnitude lower than predicted by the NE2001 model (Cordes and Lazio 2002). If this scattering time scale is representative of the GC as a whole, then previous surveys should have detected many pulsars. The lack of detections implies either our understanding of scattering in the GC is incomplete or there are fewer pulsars in the GC than previously predicted. Given that magnetars are a rare class of radio pulsar, there are likely many canonical and millisecond pulsars in the GC, and not surprisingly, scattering in the GC is spatially complex.

  10. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD+ ions (United States)

    Patra, Sayan; Koelemeij, J. C. J.


    Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD+), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel et al. (2016) presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel et al. to theoretically study the Doppler-broadened hyperfine structure of the (v, L) : (0, 3) → (4, 2) rovibrational transition in HD+ at 1442 nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine components addressed by the laser. We explain the origin and behavior of such features, and we provide a simple quantitative guideline to assess whether ghost features may appear. As such ghost features may be common to saturated Doppler-broadened spectra of rotational and vibrational transitions in trapped ions composed of partly overlapping lines, our work illustrates the necessity to use lineshape models that take into account all the relevant physics.

  11. Broadening of the Measured Frequency Spectrum in a Differential Laser Anemometer due to Interference Plane Gradients

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner


    It is shown how an inaccurate alignment of a differential laser anemometer may cause a significant broadening of the Doppler spectrum. The reason is the appearance of gradients in the interference pattern in the measuring volume. The phenomenon was investigated theoretically, and a method...

  12. Broadening Educational Outcomes: Social Relations, Skills Development, and Employability for Youth (United States)

    Dejaeghere, Joan; Wiger, Nancy Pellowski; Willemsen, Laura Wangsness


    This article argues that, if a global development aim is to address educational inequalities, the post-2015 agenda needs to conceptually and practically broaden the focus of learning to include social relations as important processes and outcomes for achieving educational equity. We draw on Sen's capability approach and Bourdieu's forms of capital…

  13. The Broadening of Activities in the Financial System : Implications for Financial Stability and Regulation

    NARCIS (Netherlands)

    Wagner, W.B.


    Conglomeration and consolidation in the financial system broaden the activities financial institutions are undertaking and cause them to become more homogenous.Although resulting diversification gains make each institution appear less risky, we argue that financial stability may not improve as total

  14. Broadening Educational Outcomes: Social Relations, Skills Development, and Employability for Youth (United States)

    Dejaeghere, Joan; Wiger, Nancy Pellowski; Willemsen, Laura Wangsness


    This article argues that, if a global development aim is to address educational inequalities, the post-2015 agenda needs to conceptually and practically broaden the focus of learning to include social relations as important processes and outcomes for achieving educational equity. We draw on Sen's capability approach and Bourdieu's forms of capital…

  15. Broadening of Plasmonic Resonance Due to Electron Collisions with Nanoparticle Boundary: а Quantum Mechanical Consideration

    DEFF Research Database (Denmark)

    Uskov, Alexander; Protsenko, Igor E.; Mortensen, N. Asger


    We present a quantum mechanical approach to calculate broadening of plasmonic resonances in metallic nanostructures due to collisions of electrons with the surface of the structure. The approach is applicable if the characteristic size of the structure is much larger than the de Broglie electron ...

  16. Saturation broadening effect in an InP photonic-crystal nanocavity switch

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel;


    Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA....

  17. Measurements of (C-12)H4 nu-4 band halfwidths using a tunable diode laser system and a Fourier transform spectrometer (United States)

    Devi, V. M.; Benner, D. C.; Rinsland, C. P.; Smith, M. A. H.


    Air-broadened and N2-broadened halfwidths at room temperature for twenty-five transitions in the nu-4 fundamental band of (C-12)H4 have been determined from IR absorption spectra recorded with a tunable diode laser spectrometer. Two tunable diode lasers operating in the 1250-1380-kayser region were used to obtain these data. Air-broadened halfwidths for twenty of these lines were also determined from additional spectra recorded at 0.01-kayser resolution with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. The air-broadened halfwidths obtained from these two techniques are very consistent with agreement better than 3 percent in most cases.

  18. Action potential broadening and frequency-dependent facilitation of calcium signals in pituitary nerve terminals. (United States)

    Jackson, M B; Konnerth, A; Augustine, G J


    Hormone release from nerve terminals in the neurohypophysis is a sensitive function of action potential frequency. We have investigated the cellular mechanisms responsible for this frequency-dependent facilitation by combining patch clamp and fluorimetric Ca2+ measurements in single neurosecretory terminals in thin slices of the rat posterior pituitary. In these terminals both action potential-induced changes in the intracellular Ca2+ concentration ([Ca2+]i) and action potential duration were enhanced by high-frequency stimuli, all with a frequency dependence similar to that of hormone release. Furthermore, brief voltage clamp pulses inactivated a K+ current with a very similar frequency dependence. These results support a model for frequency-dependent facilitation in which the inactivation of a K+ current broadens action potentials, leading to an enhancement of [Ca2+]i signals. Further experiments tested for a causal relationship between action potential broadening and facilitation of [Ca2+]i changes. First, increasing the duration of depolarization, either by broadening action potentials with the K(+)-channel blocker tetraethylammonium or by applying longer depolarizing voltage clamp steps, increased [Ca2+]i changes. Second, eliminating frequency-dependent changes in duration, by voltage clamping the terminal with constant duration pulses, substantially reduced the frequency-dependent enhancement of [Ca2+]i changes. These results indicate that action potential broadening contributes to frequency-dependent facilitation of [Ca2+]i changes. However, the small residual frequency dependence of [Ca2+]i changes seen with constant duration stimulation suggests that a second process, distinct from action potential broadening, also contributes to facilitation. These two frequency-dependent mechanisms may also contribute to activity-dependent plasticity in synaptic terminals.

  19. Line Mixing and Broadening in the Raman Q Branch of HD at 304.6 K. (United States)

    Sheldon; Sinclair; Le Flohic MP; Drummond; May


    The Q-branch lines of pure HD were measured at densities ranging from 1 to 7 Amagat at 304.6 K. Each profile was fitted to the well-known Rosenkranz expression to extract the size of the asymmetry due to line mixing as well as to the linewidth. Line mixing and broadening coefficients were obtained by fitting the asymmetries and widths to a straight line as a function of gas density. Apart from a single existing measurement for the Q(0) line, our mixing coefficients are the first direct measurements of the asymmetry due to line mixing in HD. Our broadening coefficients are consistent with the best earlier measurements but are an order of magnitude more precise. Agreement is found with some existing semiclassical calculations of broadening. We have fitted our HD broadening coefficients to a variety of empirical energy gap laws. Our conclusions are that none of the exponential gap law (EGL), the modified exponential gap (MEG) law, and the statistical power gap (SPG) law successfully models our broadening coefficients. We present a modified version of the EGL and the MEG laws, which are successful in reproducing the experimental results. Using the fitted parameters of the new gap law, we have calculated the relaxation matrix of HD at room temperature. With this relaxation matrix, we have simulated the Q-branch spectrum at a number of densities between 49.1 and 490 Amagat and compared the results with previous high-density measurements. At all densities and frequencies, the simulated spectral intensity was found to agree with the measured strength within about 5% of the peak of the spectrum. In addition, the comparison provides evidence of a nonlinear vibrational dephasing shift in HD. Copyright 1998 Academic Press.

  20. Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant

    CERN Document Server

    Triki, Meriam; Darquié, Benoît; Sow, Papa Lat Tabara; Roncin, Vincent; Chardonnet, Christian; Daussy, Christophe


    In this paper we present an accurate analysis of the shape of an isolated rovibrational ammonia line from the strong nu2 band around 10 $\\mu$m, recorded by laser absorption spectroscopy. Experimental spectra obtained under controlled temperature and pressure, are confronted to various models that take into account Dicke narrowing or speed-dependent effects. Our results show clear evidence for speed-dependent broadening and shifting, which had never been demonstrated so far in NH3. Accurate lineshape parameters of the nu2 saQ(6,3) line are obtained. Our current project aiming at measuring the Boltzmann constant, kB, by laser spectroscopy will straight away benefit from such knowledge. We anticipate that a first optical determination of kB with a competitive uncertainty of a few ppm is now reachable.

  1. Temporal reflection as a spectral-broadening mechanism in dual-pumped dispersion-decreasing fibers and its connection to dispersive waves (United States)

    Antikainen, Aku; Arteaga-Sierra, Francisco R.; Agrawal, Govind P.


    We show that temporal reflections off a moving refractive index barrier play a major role in the spectral broadening of a dual-wavelength input inside a highly nonlinear, dispersion-decreasing fiber. We also find that a recently developed linear theory of temporal reflections works well in predicting the reflected frequencies. Successive temporal reflections from multiple closely spaced solitons create a blueshifted spectral band, while continuous narrowing of solitons inside the dispersion-decreasing fiber enhances Raman-induced redshifts, leading to supercontinuum generation at relatively low pump powers. We also show how dispersive wave emission can be considered a special case of the more general process of temporal reflections. Hence our findings have implications on all systems able to support solitons.

  2. A tunable dual-broad-band branch-line coupler utilizing composite right/left-handed transmission lines

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu; HU Li; HE Sai-ling


    A tunable dual-broad-band branch-line coupler (BLC) utilizing composite right/left-handed (CRLH) transmission lines is presented. Two λ/4 segments consisting of CRLH transmission lines are added to each port to broaden the dual bands of the branch-line coupler. Numerical simulation and optimal design of the novel coupler are presented. The dual bands of the novel coupler are tunable and broad. The 1-dB bandwidth of each passband is more than 16% of the central frequency.

  3. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)

    XIANG FuYuan; LIANG ShunLin; LI AiGen


    The diffuse interstellar bands (DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s, the exact nature of DIBs still remains unclear. This article reviews the history of the detec-tions of DIBs in the Milky Way and external galaxies, the major observational characteristics of DIBs, the correlations or anti-correlations among DIBs or between DIBs and other interstellar features (e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise), and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  4. Diffuse interstellar absorption bands

    Institute of Scientific and Technical Information of China (English)


    The diffuse interstellar bands(DIBs) are a large number of absorption bands that are superposed on the interstellar extinction curve and are of interstellar origin. Since the discovery of the first two DIBs in the 1920s,the exact nature of DIBs still remains unclear. This article reviews the history of the detections of DIBs in the Milky Way and external galaxies,the major observational characteristics of DIBs,the correlations or anti-correlations among DIBs or between DIBs and other interstellar features(e.g. the prominent 2175 Angstrom extinction bump and the far-ultraviolet extinction rise),and the proposed candidate carriers. Whether they are also present in circumstellar environments is also discussed.

  5. Symmetry-Driven Band Gap Engineering in Hydrogen Functionalized Graphene. (United States)

    Jørgensen, Jakob Holm; Čabo, Antonija Grubišić; Balog, Richard; Kyhl, Line; Groves, Michael N; Cassidy, Andrew Martin; Bruix, Albert; Bianchi, Marco; Dendzik, Maciej; Arman, Mohammad Alif; Lammich, Lutz; Pascual, José Ignacio; Knudsen, Jan; Hammer, Bjørk; Hofmann, Philip; Hornekaer, Liv


    Band gap engineering in hydrogen functionalized graphene is demonstrated by changing the symmetry of the functionalization structures. Small differences in hydrogen adsorbate binding energies on graphene on Ir(111) allow tailoring of highly periodic functionalization structures favoring one distinct region of the moiré supercell. Scanning tunneling microscopy and X-ray photoelectron spectroscopy measurements show that a highly periodic hydrogen functionalized graphene sheet can thus be prepared by controlling the sample temperature (Ts) during hydrogen functionalization. At deposition temperatures of Ts = 645 K and above, hydrogen adsorbs exclusively on the HCP regions of the graphene/Ir(111) moiré structure. This finding is rationalized in terms of a slight preference for hydrogen clusters in the HCP regions over the FCC regions, as found by density functional theory calculations. Angle-resolved photoemission spectroscopy measurements demonstrate that the preferential functionalization of just one region of the moiré supercell results in a band gap opening with very limited associated band broadening. Thus, hydrogenation at elevated sample temperatures provides a pathway to efficient band gap engineering in graphene via the selective functionalization of specific regions of the moiré structure.

  6. Measured-predicted molecular spectra at band-line resolution (United States)

    Freeman, G. N.; Akagi, T.; Barton, P. B. C.


    Early ERIM measurements of hot-through-cold gas (CO2, H2O, N2) emission-absorption spectra are replicated by modern line-band computations that incorporate independent fundamental line strength-frequency information. Close agreement is achieved for all cases by empirical adjustment of the line broadening function. Line spectra for CO2 and H2O computed at 0.001 cm-1 resolution were integrated to 3.2 and 14 cm-1 using a triangular slit function consistent with ERIM measurements for the 4.3 and 2.7 μm spectral regions. Band spectra computed at 0.1 cm-1 resolution give close agreement with spectra generated at higher resolution. The findings demonstrate a merged line-band model for nonuniform path radiance and transmittance based on the line-sum spectral cross section for each piecewise-uniform path segment. The band-and-line transmittance become equivalent at high spectral resolution.

  7. DFPT approach to the temperature dependence of electronic band energies (United States)

    Boulanger, Paul; Cote, Michel; Gonze, Xavier


    The energy bands of semiconductors exhibit significant shifts and broadening with temperature at constant volume. This is an effect of the direct renormalization of band energies due to electron-phonon interactions. In search of an efficient linear response DFT approach to this effect, beyond semi-empirical approximation or frozen- phonon DFT, we have implemented formulas derived by Allen and Heine [J. Phys. C 9, 2305 (1976)] inside the ABINIT package. We have found that such formulas need a great number of bands, O(1000), to properly converge the thermal corrections of deep potential well atoms, i.e. elements of the first row. This leads to heavy computational costs even for simple systems like diamond. The DFPT formalism can be used to circumvent entirely the need for conduction bands by computing the first-order wave-functions using the self-consistent Sternheimer equation. We will compare the results of both formalism demonstrating that the DFPT approach reproduces the correct converged results of the formulas of Allen and Heine.

  8. Ca2+-activated K+ (BK) channel inactivation contributes to spike broadening during repetitive firing in the rat lateral amygdala. (United States)

    Faber, E S Louise; Sah, Pankaj


    In many neurons, trains of action potentials show frequency-dependent broadening. This broadening results from the voltage-dependent inactivation of K+ currents that contribute to action potential repolarisation. In different neuronal cell types these K+ currents have been shown to be either slowly inactivating delayed rectifier type currents or rapidly inactivating A-type voltage-gated K+ currents. Recent findings show that inactivation of a Ca2+-dependent K+ current, mediated by large conductance BK-type channels, also contributes to spike broadening. Here, using whole-cell recordings in acute slices, we examine spike broadening in lateral amygdala projection neurons. Spike broadening is frequency dependent and is reversed by brief hyperpolarisations. This broadening is reduced by blockade of voltage-gated Ca2+ channels and BK channels. In contrast, broadening is not blocked by high concentrations of 4-aminopyridine (4-AP) or alpha-dendrotoxin. We conclude that while inactivation of BK-type Ca2+-activated K+ channels contributes to spike broadening in lateral amygdala neurons, inactivation of another as yet unidentified outward current also plays a role.

  9. Scatter broadening of compact radio sources by the ionized intergalactic medium: Prospects for detection with Space VLBI and the SKA

    CERN Document Server

    Koay, J Y


    We investigate the feasibility of detecting and probing various components of the ionized intergalactic medium (IGM) and their turbulent properties at radio frequencies through observations of scatter broadening of compact sources. There is a strong case for conducting targeted observations to resolve scatter broadening (where the angular size scales as $\\sim \

  10. Micromechanics of shear banding

    Energy Technology Data Exchange (ETDEWEB)

    Gilman, J.J.


    Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

  11. Photonic band gap enhancement in frequency-dependent dielectrics. (United States)

    Toader, Ovidiu; John, Sajeev


    We illustrate a general technique for evaluating photonic band structures in periodic d -dimensional microstructures in which the dielectric constant epsilon (omega) exhibits rapid variations with frequency omega . This technique involves the evaluation of generalized electromagnetic dispersion surfaces omega ( k--> ,epsilon) in a (d+1) -dimensional space consisting of the physical d -dimensional space of wave vectors k--> and an additional dimension defined by the continuous, independent, variable epsilon . The physical band structure for the photonic crystal is obtained by evaluating the intersection of the generalized dispersion surfaces with the "cutting surface" defined by the function epsilon (omega) . We apply this method to evaluate the band structure of both two- and three-dimensional (3D) periodic microstructures. We consider metallic photonic crystals with free carriers described by a simple Drude conductivity and verify the occurrence of electromagnetic pass bands below the plasma frequency of the bulk metal. We also evaluate the shift of the photonic band structure caused by free carrier injection into semiconductor-based photonic crystals. We apply our method to two models in which epsilon (omega) describes a resonant radiation-matter interaction. In the first model, we consider the addition of independent, resonant oscillators to a photonic crystal with an otherwise frequency-independent dielectric constant. We demonstrate that for an inhomogeneously broadened distribution of resonators impregnated within an inverse opal structure, the full 3D photonic band gap (PBG) can be considerably enhanced. In the second model, we consider a coupled resonant oscillator mode in a photonic crystal. When this mode is an optical phonon, there can be a synergetic interplay between the polaritonic resonance and the geometrical scattering resonances of the structured dielectric, leading to PBG enhancement. A similar effect may arise when resonant atoms that are

  12. Excitatory amino acids acting on metabotropic glutamate receptors broaden the action potential in hippocampal neurons. (United States)

    Hu, G Y; Storm, J F


    Activation of metabotropic glutamate receptors (mGluRs, QP or ACPD receptors) has recently been shown to cause depolarization, blockade of the slow after-hyperpolarization and depression of calcium currents in hippocampal pyramidal cells. Here, we report evidence for a new mGluR-mediated effect: slowing of the spike repolarization in CA1 cells in rat hippocampal slices. During blockade of the ionotropic glutamate receptors, the mGluR agonists trans-1-amino-cyclopentyl-1,3-dicarboxylate (t-ACPD), quisqualate or L-glutamate caused spike broadening. In contrast, the ionotropic receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) was ineffective. The spike broadening may act in concert with the other mGluR effects, e.g. by further increasing the influx of Ca2+ ions which, in turn, may contribute to synaptic modulation.

  13. Phorbol esters broaden the action potential in CA1 hippocampal pyramidal cells. (United States)

    Storm, J F


    Intracellular recordings were made from CA1 pyramidal cells in rat hippocampal slices. Single action potentials were elicited by injection of brief current pulses. Bath application of phorbol esters (4 beta-phorbol-12,13-diacetate, 0.3-5 microM; or 4 beta-phorbol-12,13-dibutyrate, 5-10 microM) broadened the action potential in each of the cells tested (n = 9). The broadening reflected slowing of the repolarization, whereas the upstroke of the spike was unchanged. This effect may enhance transmitter release from synaptic terminals, and contribute to enhancement of synaptic transmission through activation of protein kinase C, a mechanism which has been associated with long term potentiation.

  14. From discrete to continuous the broadening of number concepts in early modern England

    CERN Document Server

    Neal, Katherine


    In the early modern period, a crucial transformation occurred in the classical conception of number and magnitude. Traditionally, numbers were merely collections of discrete units that measured some multiple. Magnitude, on the other hand, was usually described as being continuous, or being divisible into parts that are infinitely divisible. This traditional idea of discrete number versus continuous magnitude was challenged in the early modern period in several ways. This detailed study explores how the development of algebraic symbolism, logarithms, and the growing practical demands for an expanded number concept all contributed to a broadening of the number concept in early modern England. An interest in solving practical problems was not, in itself, enough to cause a generalisation of the number concept. It was the combined impact of novel practical applications together with the concomitant development of such mathematical advances as algebraic notation and logarithms that produced a broadened number conce...

  15. Transverse momentum broadening in semi-inclusive deep inelastic scattering at next-to-leading order (United States)

    Kang, Zhong-Bo; Wang, Enke; Wang, Xin-Nian; Xing, Hongxi


    Within the framework of higher-twist collinear factorization, transverse momentum broadening for the final hadrons in semi-inclusive deeply inelastic e +A collisions is studied at the next-to-leading order (NLO) in perturbative QCD. Through explicit calculations of real and virtual corrections at twist 4, the transverse-momentum-weighted differential cross section due to double scattering is shown to factorize at NLO and can be expressed as a convolution of twist-4 nuclear parton correlation functions, the usual twist-2 fragmentation functions and hard parts which are finite and free of any divergences. A QCD evolution equation is also derived for the renormalized twist-4 quark-gluon correlation function which can be applied to future phenomenological studies of transverse momentum broadening and jet quenching at NLO.

  16. Dielectric spectra broadening as the signature of dipole-matrix interaction. II. Water in ionic solutions. (United States)

    Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ben Ishai, Paul; Feldman, Yuri


    In this, the second part of our series on the dielectric spectrum symmetrical broadening of water, we consider ionic aqueous solutions. If in Part I, dipole-dipole interaction was the dominant feature, now ion-dipole interplay is shown to be the critical element in the dipole-matrix interaction. We present the results of high-frequency dielectric measurements of different concentrations of NaCl/KCl aqueous solutions. We observed Cole-Cole broadening of the main relaxation peak of the solvent in the both electrolytes. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the dynamics and structure of solutions of salts on one hand and dipolar solutes on the other hand.

  17. In-medium jet evolution: interplay between broadening and decoherence effects

    CERN Document Server

    Apolinário, Liliana; Milhano, Guilherme; Salgado, Carlos A.


    The description of the modifications of the coherence pattern in a parton shower, in the presence of a QGP, has been actively addressed in recent studies. Among the several achievements, finite energy corrections, transverse momentum broadening due to medium interactions and interference effects between successive emissions have been extensively improved as they seem to be essential features for a correct description of the results obtained in heavy-ion collisions. In this work, based on the insights of our previous work [1], we explore the physical interplay between broadening and decoherence, by generalising previous studies of medium-modifications of the antenna spectrum [2, 3, 4] - so far restricted to the case where transverse motion is neglected. The result allow us to identify two quantities controlling the decoherence of a medium modified shower that can be used as building blocks for a successful future generation of jet quenching Monte Carlo simulators: a generalisation of the $\\Delta_{med}$ paramet...

  18. Stark Broadening of in III Lines in Astrophysical and Laboratory Plasma

    CERN Document Server

    Simic, Z; Kovacevic, A B; Sahal-Brechot, S


    Besides the need of Stark broadening parameters for a number of problems in physics, and plasma technology, in hot star atmospheres the conditions exist where Stark widths are comparable and even larger than the thermal Doppler widths. Using the semiclassical perturbation method we investigated here the influence of collisions with charged particles for In III spectral lines. We determined a number of Stark broadening parameters important for the investigation of plasmas in the atmospheres of A-type stars and white dwarfs. Also, we have compared the obtained results with existing experimental data. The results will be included in the STARK-B database, the Virtual Atomic and Molecular Data Center and the Serbian Virtual Observatory.

  19. Impact of echo broadening effect on active range-gated imaging

    Institute of Scientific and Technical Information of China (English)

    Xinwei Wang; Yan Zhou; Yuliang Liu


    Analytical formulas and experimental proof of the echo broadening effect in active range-gated imaging,including atmospheric interference,currently exist.We investigate the impact of this effect on target detection.Our research demonstrates that the echo broadening effect affects the energy profile of the depth of view and collects only part of the signals of targets in head and tail zones.Under bad weather conditions,the effect weakens the signal-to-noise ratio (SNR) of images,especially in cases with large laser pulse width.Fortunately,by modifying the laser pulse width,the effect can be controlled.These results are valuable to the applications of active range-gated imaging.

  20. Spectral broadening in anatase titanium dioxide waveguides at telecommunication and near-visible wavelengths. (United States)

    Evans, Christopher C; Shtyrkova, Katia; Bradley, Jonathan D B; Reshef, Orad; Ippen, Erich; Mazur, Eric


    We observe spectral broadening of femtosecond pulses in single-mode anatase-titanium dioxide (TiO(2)) waveguides at telecommunication and near-visible wavelengths (1565 and 794 nm). By fitting our data to nonlinear pulse propagation simulations, we quantify nonlinear optical parameters around 1565 nm. Our fitting yields a nonlinear refractive index of 0.16 × 10(-18) m(2)/W, no two-photon absorption, and stimulated Raman scattering from the 144 cm(-1) Raman line of anatase with a gain coefficient of 6.6 × 10(-12) m/W. Additionally, we report on asymmetric spectral broadening around 794 nm. The wide wavelength applicability and negligible two-photon absorption of TiO(2) make it a promising material for integrated photonics.

  1. Quantification of tip-broadening in non-contact atomic force microscopy with carbon nanotube tips

    DEFF Research Database (Denmark)

    Meinander, Kristoffer; Jensen, Thomas N.; Simonsen, Soren B.;


    Carbon nanotube terminated atomic force microscopy (AFM) probes have been used for the imaging of 5 nm wide surface supported Pt nanoclusters by non-contact (dynamic mode) AFM in an ultra-high vacuum. The results are compared to AFM measurements done with conventional Si-tips, as well...... as with transmission electron microscopy images, which give accurate measures for cluster widths. Despite their ideal aspect ratio, tip-broadening is concluded to be a severe problem even when imaging with carbon nanotube tips, which overestimates the cluster width by several times the nominal width of the nanotube...... tip. This broadening is attributed to a bending of the carbon nanotubes, and not to pure geometrical factors, which coincidentally results in a significant improvement for relative height measurements of tightly spaced high aspect ratio structures, as compared to what can be achieved...


    Institute of Scientific and Technical Information of China (English)



    This paper deals with the absorption spectra of a weak probe in a four-level Doppler-broadened system driven by three coherent fields. The main aim is to extend earlier studies of the spontaneous emission spectrum and to present a comprehensive survey of the spectral features of this system. In addition to a derivation of exact formulae for the spectra, we give an explanation with the help of an appropriate set of dressed atomic states. We also get a deeper insight into the physical origin of gain in view of the existence of a population inversion between the levels of the lasing transition. Finally, we explore the effect of Doppler broadening on the absorption profile of the weak probe.

  3. Position sensitivity in large spectroscopic LaBr3:Ce crystals for Doppler broadening correction (United States)

    Blasi, N.; Giaz, A.; Boiano, C.; Brambilla, S.; Camera, F.; Million, B.; Riboldi, S.


    The position sensitivity of a large LaBr3:Ce crystal was investigated with the aim of correcting for the Doppler broadening in nuclear physics experiments. The crystal was cylindrical, 3 in×3 in (7.62 cm x 7.62 cm) and with diffusive surfaces as typically used in nuclear physics basic research to measure medium or high energy gamma rays (0.5 MeVbroadening induced by relativistic beams in Nuclear Physics experiments.

  4. Positron life time and annihilation Doppler broadening measurements on transition metal complexes

    Energy Technology Data Exchange (ETDEWEB)

    Levay, B. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Fizikai Kemiai es Radiologiai Tanszek); Varhelyi, Cs. (Babes-Bolyai Univ., Cluj (Romania)); Burger, K. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Szervetlen es Analitikai Kemiai Intezet)


    Positron life time and annihilation Doppler broadening measurements have been carried out on 44 solid coordination compounds. Several correlations have been found between the annihilation life time (tau/sub 1/) and line shape parameters (L) and the chemical structure of the compounds. Halide ligands were the most active towards positrons. This fact supports the assumption on the possible formation of (e/sup +/X/sup -/) positron-halide bound state. The life time was decreasing and the annihilation energy spectra were broadening with the increasing negative character of the halides. The aromatic base ligands affected the positron-halide interaction according to their basicity and space requirement and thus they indirectly affected the annihilation parameters, too. In the planar and tetrahedral complexes the electron density on the central met--al ion affected directly the annihilation parameters, while in the octahedral mixed complexes it had only an ind--irect effect through the polarization of the halide ligands.

  5. Determination of the Ion Velocity Distribution in a Rotating Plasma from Measurements of Doppler Broadening

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, Alfred Hegaard


    The Doppler-broadened profile of the He II 4685.75 AA line was measured along a chord in a rotating plasma, transverse to the magnetic field. Using a single-particle orbit picture, the corresponding velocity spectrum of ions confirm the measurements, so it can be concluded that the single......-particle orbit picture is valid for the discharge period under investigation, except for the first few microseconds during breakdown when a strong interaction between plasma and remaining neutral gas takes place by Alfvens critical velocity mechanism. A simple relation is given between the measured half......-width and shift of the Doppler profile and the macroscopic quantities of ion velocity and energy. Several Doppler-broadened profiles are shown for different plasma parameters....

  6. Stochastic analysis of spectral broadening by a free turbulent shear layer (United States)

    Hardin, J. C.; Preisser, J. S.


    The effect of the time-varying shear layer between a harmonic acoustic source and an observer on the frequency content of the observed sound is considered. Experimental data show that the spectral content of the acoustic signal is considerably broadened upon passing through such a shear layer. Theoretical analysis is presented which shows that such spectral broadening is entirely consistent with amplitude modulation of the acoustic signal by the time-varying shear layer. Thus, no actual frequency shift need be hypothesized to explain the spectral phenomenon. Experimental tests were conducted at 2, 4, and 6 kHz and at free jet flow velocities of 10, 20, and 30 m/s. Analysis of acoustic pressure time histories obtained from these tests confirms the above conclusion, at least for the low Mach numbers considered.

  7. Spectral Line Non-thermal Broadening and MHD Waves in the Solar Corona (United States)

    Zaqarashvili, T. V.


    The rapid temperature rise from the solar surface (6000 K) up to the corona (1 MK) and acceleration of solar wind particles still are unresolved problems in solar physics. The energy source for the coronal heating and the wind acceleration probably lies in the solar photosphere. MHD waves are believed to carry the photospheric energy into the corona. Recent observations from space based telescopes made significant progress in understanding the process of MHD wave propagation from the solar surface towards the corona. Some of MHD wave modes have been observed through intensity variations and Doppler shift oscillations in spectral lines. Another powerful mechanism is to detect the waves through the non-thermal broadening of spectral lines. The lecture gives the basic points of wave induced effects in solar coronal spectral lines and recent progress in wave observations through spectral line non-thermal broadening.

  8. Parton energy loss and momentum broadening at NLO in high temperature QCD plasmas

    CERN Document Server

    Ghiglieri, Jacopo


    We present an overview of a perturbative-kinetic approach to jet propagation, energy loss, and momentum broadening in a high temperature quark-gluon plasma. The leading-order kinetic equations describe the interactions between energetic jet-particles and a non-abelian plasma, consisting of on-shell thermal excitations and soft gluonic fields. These interactions include 22 scatterings, collinear bremsstrahlung, and drag and momentum diffusion. We show how the contribution from the soft gluonic fields can be factorized into a set of Wilson line correlators on the light cone. We review recent field-theoretical developments, rooted in the causal properties of these correlators, which simplify the calculation of the appropriate Wilson lines in thermal field theory. With these simplifications lattice measurements of transverse momentum broadening have become possible, and the kinetic equations describing parton transport have been extended to next-to-leading order in the coupling g.

  9. The Wulf bands of oxygen (United States)

    Bernath, Peter; Carleer, Michel; Fally, Sophie; Jenouvrier, Alain; Vandaele, Ann Carine; Hermans, Christian; Mérienne, Marie-France; Colin, Reginald


    The Wulf bands of oxygen in the 240-290 nm spectral region are caused by collision-induced absorption of the Herzberg III ( A' 3Δu- X3Σ-g) system. These bands had been previously attributed to the oxygen dimer, (O 2) 2. Under atmospheric conditions the Wulf bands are thus the long-wavelength extension of the Herzberg continuum. Absorption of solar radiation by the Wulf bands may be an additional source of NO in the stratosphere.

  10. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K


    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  11. Doppler broadening effect on collision cross section functions - Deconvolution of the thermal averaging (United States)

    Bernstein, R. B.


    The surprising feature of the Doppler problem in threshold determination is the 'amplification effect' of the target's thermal energy spread. The small thermal energy spread of the target molecules results in a large dispersion in relative kinetic energy. The Doppler broadening effect in connection with thermal energy beam experiments is discussed, and a procedure is recommended for the deconvolution of molecular scattering cross-section functions whose dominant dependence upon relative velocity is approximately that of the standard low-energy form.

  12. Linewidth broadening of a quantum dot coupled to an off-resonant cavity

    CERN Document Server

    Majumdar, Arka; Kim, Erik; Englund, Dirk; Kim, Hyochul; Petroff, Pierre; Vuckovic, Jelena


    We study the coupling between a photonic crystal cavity and an off-resonant quantum dot under resonant excitation of the cavity or the quantum dot. Linewidths of the quantum dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the quantum dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the quantum dot and the cavity.

  13. Infantile nystagmus syndrome: Broadening the high-foveation-quality field with contact lenses

    Directory of Open Access Journals (Sweden)

    Giovanni Taibbi


    Full Text Available Giovanni Taibbi1,4,5, Zhong I Wang1,3, Louis F Dell’Osso1–31The Daroff-Dell’Osso Ocular Motility Laboratory, Louis Stokes Cleveland Department of Veterans Affairs Medical Center and CASE Medical School; 2Department of Neurology; 3Department of Biomedical Engineering, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, USA; 4Pediatric Ophthalmology and Strabismus Unit, San Paolo Hospital, Milan, Italy; 5University of Milan, Milan, ItalyAbstract: We investigated the effects of contact lenses in broadening and improving the high-foveation-quality field in a subject with infantile nystagmus syndrome (INS. A high-speed, digitized video system was used for the eye-movement recording. The subject was asked to fixate a far target at different horizontal gaze angles with contact lenses inserted. Data from the subject while fixating at far without refractive correction and at near (at a convergence angle of 60 PD, were used for comparison. The eXpanded Nystagmus Acuity Function (NAFX was used to evaluate the foveation quality at each gaze angle. Contact lenses broadened the highfoveation-quality range of gaze angles in this subject. The broadening was comparable to that achieved during 60 PD of convergence although the NAFX values were lower. Contact lenses allowed the subject to see “more” (he had a wider range of high-foveation-quality gaze angles and “better” (he had improved foveation at each gaze angle. Instead of being contraindicated by INS, contact lenses emerge as a potentially important therapeutic option. Contact lenses employ afferent feedback via the ophthalmic division of the V cranial nerve to damp INS slow phases over a broadened range of gaze angles. This supports the proprioceptive hypothesis of INS improvement.Keywords: contact lenses, infantile nystagmus, visual function

  14. Deconvolution of Lorentzian broadened spectra. Pt. 2. Stepped deconvolution and smooting filtration

    Energy Technology Data Exchange (ETDEWEB)

    Kantchev, K.; Nikolov, S.


    A new method of numerical time domain deconvolution of Lorentzian broadened spectra is proposed. The new algorithm consist in convolution with a deconvoluting function accomplished by a preset step, so that an undersampling of the input spectra is performed. The main advantage of this method is the considerable reduction of the noise enhancement. A theoretical analysis of the possibilities, the restrictions and the errors is done. The results are confirmed by test investigations and by experimental examples.

  15. Anisotropic peak broadening analysis of SRS diffraction from twin microstructurs in YBCO sample

    Directory of Open Access Journals (Sweden)

    B Khoshnevisan


    Full Text Available Reitveld full profile refinement analysis has been done on Synchrotron diffraction data from a powder sample of YBCOx at RT and 500°C. Anisotropic peak broadening for (h00 and (hh0 lines has been observed by Williamson-Hall (W-H analysis and that is in agreement with formation of twin's microstructures along (110 crystal planes in the sample. In addition, size and strain of the crystallites has been inferred in our study also.

  16. Four-wave mixing at maximum coherence and eliminated Doppler broadening controlled with the driving fields

    CERN Document Server

    Popov, A K; George, T F; Shalaev, V M; Bayev, Alexander S.; George, Thomas F.; Shalaev, Vladimir M.


    New feasibity of coherent quantum control of four-wave mixing processes in a resonant Doppler-broadened medium are studied. We propose a technique which enables one to enhance the quantum efficiency of nonlinear optical conversion. At the same time, it allows one to decrease the required intensities of the fundamental beams compared to those necessary in the approach based on coherent population trapping. The major outcomes of the analysis are illustrated with numerical simulation addressed within a practical medium.

  17. Broadening of length distributions of Au-catalyzed InAs nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Berdnikov, Yury, E-mail: [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); Sibirev, Nikolay [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); St. Petersburg State Polytechnical University, 195251 St-Petersburg (Russian Federation); Schmidtbauer, Jan [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany); Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); Borg, Mattias [Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); IBM Research – Zurich, Säumerstrasse 4, 8803 Rüschlikon (Switzerland); Johansson, Jonas [Solid State Physics and NanoLund, Lund University, Box 118, S-22100 Lund (Sweden); Dubrovskii, Vladimir [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); St. Petersburg State University, Physical Faculty, Ulianovskaya Street 3, Petrodvorets, 198504 St. Petersburg (Russian Federation); ITMO University, Kronverkskiy pr. 49, 197101 St. Petersburg (Russian Federation)


    We investigate kinetic broadening effects on the length distributions of gold-catalyzed InAs nanowires having different diameters. It is shown that the length distributions acquire bimodal shape when the longest nanowires exceed the diffusion length of indium adatoms on the nanowire sidewalls. Later on, the length distributions recover unimodal shapes. We develop a theoretical model that is capable of describing the observed behaviors by accounting for the diffusion-induced character of the vapor-liquid-solid growth.

  18. Toward a Broadband Astro-comb: Effects of Nonlinear Spectral Broadening in Optical Fibers

    CERN Document Server

    Chang, Guoqing; Phillips, David F; Walsworth, Ronald L; Kärtner, Franz X


    We propose and analyze a new approach to generate a broadband astro-comb by spectral broadening of a narrowband astro-comb inside a highly nonlinear optical fiber. Numerical modeling shows that cascaded four-wave-mixing dramatically degrades the input comb's side-mode suppression and causes side-mode amplitude asymmetry. These two detrimental effects can systematically shift the center-of-gravity of astro-comb spectral lines as measured by an astrophysical spectrograph with resolution \\approx100,000; and thus lead to wavelength calibration inaccuracy and instability. Our simulations indicate that this performance penalty, as a result of nonlinear spectral broadening, can be compensated by using a filtering cavity configured for double-pass. As an explicit example, we present a design based on an Yb-fiber source comb (with 1 GHz repetition rate) that is filtered by double-passing through a low finesse cavity (finesse = 208), and subsequent spectrally broadened in a 2-cm, SF6-glass photonic crystal fiber. Spann...

  19. Stark broadening measurements in plasmas produced by laser ablation of hydrogen containing compounds (United States)

    Burger, Miloš; Hermann, Jörg


    We present a method for the measurement of Stark broadening parameters of atomic and ionic spectral lines based on laser ablation of hydrogen containing compounds. Therefore, plume emission spectra, recorded with an echelle spectrometer coupled to a gated detector, were compared to the spectral radiance of a plasma in local thermal equilibrium. Producing material ablation with ultraviolet nanosecond laser pulses in argon at near atmospheric pressure, the recordings take advantage of the spatially uniform distributions of electron density and temperature within the ablated vapor. By changing the delay between laser pulse and detector gate, the electron density could be varied by more than two orders of magnitude while the temperature was altered in the range from 6,000 to 14,000 K. The Stark broadening parameters of transitions were derived from their simultaneous observation with the hydrogen Balmer alpha line. In addition, assuming a linear increase of Stark widths and shifts with electron density for non-hydrogenic lines, our measurements indicate a change of the Stark broadening-dependence of Hα over the considered electron density range. The presented results obtained for hydrated calcium sulfate (CaSO4ṡ2H2O) can be extended to any kind of hydrogen containing compounds.

  20. On the origin of the scatter broadening of fast radio burst pulses and astrophysical implications

    CERN Document Server

    Xu, Siyao


    Fast radio bursts (FRBs) have been identified as extragalactic sources which can make a probe of turbulence in the intergalactic medium (IGM) and their host galaxies. To account for the observed millisecond pulses caused by scatter broadening, we examine a variety of possible models of electron density fluctuations in both the IGM and the host galaxy medium. We find that a shallow power-law spectrum of density, which may arise in highly supersonic turbulence with pronounced local dense structures of shock-compressed gas in the host interstellar medium (ISM), can produce the required density enhancements at sufficiently small scales to interpret the scattering timescale of FRBs. It implies that an FRB residing in a galaxy with efficient star formation in action tends to have a broadened pulse. The scaling of the scattering time with dispersion measure (DM) in the host galaxy varies in different turbulence and scattering regimes. The host galaxy can be the major origin of scatter broadening, but contribute to a...

  1. New determination of the core-level life-time broadenings in mercury

    Energy Technology Data Exchange (ETDEWEB)

    Martensson, Nils, E-mail:; Svensson, Svante


    Highlights: • We report core-level life-time widths for mercury in the gas phase. • Photoelectron spectra for the 4p, 4d, 4f and 5p levels are analyzed. • A Coster–Kronig like CI effect is observed for the 4d{sub 3/2} level. - Abstract: Previously recorded and published photoelectron spectroscopic data for mercury in the gas phase has been reanalyzed. The life-time broadenings have been determined for a large number of core levels. It is then seen that a recent detailed derivation of core-level line-widths based on X-ray emission spectroscopy give life-time widths that are generally too large. The 4d{sub 3/2}4d{sub 5/2}nd Coster–Kronig (CK) transition is also discussed. We find that the additional broadening of the 4d{sub 3/2} level for mercury metal is indeed due to a CK decay, in contrast to recent claims. In atomic mercury, however, the CK process in energetically forbidden. In spite of this we find that the 4d{sub 3/2} level is broadened also in this case. We propose that this is due to a mixing between the 4d{sub 3/2} hole state and discrete 4d{sub 5/2}nd states.

  2. Magnetic excitations and anomalous spin-wave broadening in multiferroic FeV2O4

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang [Ames Laboratory; Ramazanoglu, Mehmet [Ames Laboratory; Chi, Songxue [Oak Ridge National Laboratory; Liu, Yong [Ames Laboratory; Lograsso, Thomas A. [Ames Laboratory; Vaknin, David [Ames Laboratory


    We report on the different roles of two orbital-active Fe2+ at the A site and V3+ at the B site in the magnetic excitations and on the anomalous spin-wave broadening in FeV2O4. FeV2O4 exhibits three structural transitions and successive paramagnetic (PM)–collinear ferrimagnetic (CFI)–noncollinear ferrimagnetic (NCFI)/ferroelectric transitions. The high-temperature tetragonal/PM–orthorhombic/CFI transition is accompanied by the appearance of a large energy gap in the magnetic excitations due to strong spin-orbit-coupling-induced anisotropy at the Fe2+ site. While there is no measurable increase in the energy gap from the orbital ordering of V3+ at the orthorhombic/CFI–tetragonal/NCFI transition, anomalous spin-wave broadening is observed in the orthorhombic/CFI state due to V3+ spin fluctuations at the B site. The spin-wave broadening is also observed at the zone boundary without softening in the NCFI/ferroelectric phase, which is discussed in terms of magnon-phonon coupling. Our study also indicates that the Fe2+ spins without the frustration at the A site may not play an important role in inducing ferroelectricity in the tetragonal/NCFI phase of FeV2O4.

  3. Pressure-broadening of water transitions near 7180 cm(-1) by helium isotopes. (United States)

    Campbell, H M; Havey, D K


    In this study, pressure-broadening parameters for several H2O transitions near 7180 cm(-1) are obtained which describe collisions with (3)He and (4)He. The sensitivity of those parameters to choice of theoretical line profile (Galatry vs. Voigt) is investigated. H2O is an important species in atmospheric chemistry and astronomy. Because of this, basic fundamental research, which explores the nature of the H2O spectrum in the presence of different gases of varying physical properties, can provide useful reference data which can be applied in the fields of atmospheric and planetary remote sensing. Measurements were made using an intensity-modulated laser photoacoustic spectrometer. Results from the present work show that Galatry line profiles, with a constrained narrowing parameter, more accurately describe experimental spectra than Voigt profiles over a wide range of experimental pressure conditions. Average pressure-broadening parameters were found to be 0.0216 cm(-1)/atm and 0.0209 cm(-1)/atm for H2O in (3)He and (4)He, respectively, and were compared to a literature model for the mass-dependence of line broadening. Specific values were obtained for each transition with nominal combined uncertainties of 2-6%.

  4. Proton Lateral Broadening Distribution Comparisons Between GRNTRN, MCNPX, and Laboratory Beam Measurements (United States)

    Mertens, Christopher J.; Moyers, Michael F.; Walker, Steven A.; Tweed, John


    Recent developments in NASA s deterministic High charge (Z) and Energy TRaNsport (HZETRN) code have included lateral broadening of primary ion beams due to small-angle multiple Coulomb scattering, and coupling of the ion-nuclear scattering interactions with energy loss and straggling. This new version of HZETRN is based on Green function methods, called GRNTRN, and is suitable for modeling transport with both space environment and laboratory boundary conditions. Multiple scattering processes are a necessary extension to GRNTRN in order to accurately model ion beam experiments, to simulate the physical and biological-effective radiation dose, and to develop new methods and strategies for light ion radiation therapy. In this paper we compare GRNTRN simulations of proton lateral broadening distributions with beam measurements taken at Loma Linda University Proton Therapy Facility. The simulated and measured lateral broadening distributions are compared for a 250 MeV proton beam on aluminum, polyethylene, polystyrene, bone substitute, iron, and lead target materials. The GRNTRN results are also compared to simulations from the Monte Carlo MCNPX code for the same projectile-target combinations described above.

  5. Overcoming artificial broadening in Gd(3+)-Gd(3+) distance distributions arising from dipolar pseudo-secular terms in DEER experiments. (United States)

    Cohen, Marie Ramirez; Frydman, Veronica; Milko, Petr; Iron, Mark A; Abdelkader, Elwy H; Lee, Michael D; Swarbrick, James D; Raitsimring, Arnold; Otting, Gottfried; Graham, Bim; Feintuch, Akiva; Goldfarb, Daniella


    By providing accurate distance measurements between spin labels site-specifically attached to bio-macromolecules, double electron-electron resonance (DEER) spectroscopy provides a unique tool to probe the structural and conformational changes in these molecules. Gd(3+)-tags present an important family of spin-labels for such purposes, as they feature high chemical stability and high sensitivity in high-field DEER measurements. The high sensitivity of the Gd(3+) ion is associated with its high spin (S = 7/2) and small zero field splitting (ZFS), resulting in a narrow spectral width of its central transition at high fields. However, under the conditions of short distances and exceptionally small ZFS, the weak coupling approximation, which is essential for straightforward DEER data analysis, becomes invalid and the pseudo-secular terms of the dipolar Hamiltonian can no longer be ignored. This work further explores the effects of pseudo-secular terms on Gd(3+)-Gd(3+) DEER measurements using a specifically designed ruler molecule; a rigid bis-Gd(3+)-DOTA model compound with an expected Gd(3+)-Gd(3+) distance of 2.35 nm and a very narrow central transition at the W-band (95 GHz). We show that the DEER dipolar modulations are damped under the standard W-band DEER measurement conditions with a frequency separation, Δν, of 100 MHz between the pump and observe pulses. Consequently, the DEER spectrum deviates considerably from the expected Pake pattern. We show that the Pake pattern and the associated dipolar modulations can be restored with the aid of a dual mode cavity by increasing Δν from 100 MHz to 1.09 GHz, allowing for a straightforward measurement of a Gd(3+)-Gd(3+) distance of 2.35 nm. The increase in Δν increases the contribution of the |-5/2〉→|-3/2〉 and |-7/2〉→|-5/2〉 transitions to the signal at the expense of the |-3/2 〉→|-1/2〉 transition, thus minimizing the effect of dipolar pseudo-secular terms and restoring the validity of the weak

  6. Morphologies of omega band auroras (United States)

    Sato, Natsuo; Yukimatu, Akira Sessai; Tanaka, Yoshimasa; Hori, Tomoaki


    We examined the morphological signatures of 315 omega band aurora events observed using the Time History of Events and Macroscale Interactions during Substorm ground-based all-sky imager network over a period of 8 years. We find that omega bands can be classified into the following three subtypes: (1) classical (O-type) omega bands, (2) torch or tongue (T-type) omega bands, and (3) combinations of classical and torch or tongue (O/T-type) omega bands. The statistical results show that T-type bands occur the most frequently (45%), followed by O/T-type bands (35%) and O-type bands (18%). We also examined the morphologies of the omega bands during their formation, from the growth period to the declining period through the maximum period. Interestingly, the omega bands are not stable, but rather exhibit dynamic changes in shape, intensity, and motion. They grow from small-scale bumps (seeds) at the poleward boundary of preexisting east-west-aligned auroras, rather than via the rotation or shear motion of preexisting east-west-aligned auroras, and do not exhibit any shear motion during the periods of auroral activity growth. Furthermore, the auroral luminosity is observed to increase during the declining period, and the total time from the start of the growth period to the end of the declining period is found to be about 20 min. Such dynamical signatures may be important in determining the mechanism responsible for omega band formation.

  7. Wide Band Artificial Pulsar (United States)

    Parsons, Zackary


    The Wide Band Artificial Pulsar (WBAP) is an instrument verification device designed and built by the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virgina. The site currently operates the Green Bank Ultimate Pulsar Processing Instrument (GUPPI) and the Versatile Green Bank Astronomical Spectrometer (VEGAS) digital backends for their radio telescopes. The commissioning and continued support for these sophisticated backends has demonstrated a need for a device capable of producing an accurate artificial pulsar signal. The WBAP is designed to provide a very close approximation to an actual pulsar signal. This presentation is intended to provide an overview of the current hardware and software implementations and to also share the current results from testing using the WBAP.

  8. Progress in the measurement of temperature-dependent N2-N2 collision-induced absorption and H2-broadening of cold and hot CH4 (United States)

    Sung, Keeyoon; Wishnow, Ed; Venkataraman, Malathy; Brown, Linda R.; Ozier, Irving; Benner, D. Chris; Crawford, Tomithy J.; Mantz, Arlan; Smith, Mary-Ann H.


    We report preliminary measurements from two separate laboratory studies: (A) collision-induced absorption (CIA) of nitrogen in the far-infrared at temperatures between 78 and 130 K; and (B) temperature dependence of H2-broadening of CH4 in the near infrared at temperatures between 100 and 370 K.(A) Nitrogen collision-induced absorption provides the primary opacity of Titan at long wavelengths, thereby playing a critical role in determining the heat balance as well as the atmospheric composition and dynamics. Our new measurements of the nitrogen absorption spectrum at temperatures from 78 to 130 K are consistently ~20% higher than predictions made using theoretical models of Borysow and Frommhold (1986) [ApJ, 311, 1043] and of Karman et al. (2015)[J Chem Phys, 142, 084306]. However, the new data are consistent with the previous measurements at 78 K by the UBC group (Wishnow et al. 1996)[J Chem Phys, 104, 3511]. We present preliminary results for the N2-N2 CIA coefficients and their temperature dependence between 78 and 130 K, and comparisons with the above theoretical calculations.(B) In support of the Jovian and exoplanet atmospheric remote sensing in the near infrared, we have measured the temperature dependence of H2-broadened half width and pressure shift coefficients of CH4, both of which are known to be rotational quantum number dependent. We studied both cold and hot CH4 in the K band (~2.2 μm) with the focus on a) weaker lines in the v2+v3 band at low temperatures for cold giant planets and b) stronger lines in the v3+v4 band at elevated temperatures for extra-solar planets (e.g., hot-Jupiters). Three custom-built gas absorption cells (two cold and one hot) were used to obtain the spectra of CH4 and H2 mixtures at temperatures between 100 and 370 K. We will discuss our on-going spectrum analysis for a few select J manifolds and provide comparisons with published values, which are available only at room temperature.

  9. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

    Energy Technology Data Exchange (ETDEWEB)

    Vos, M. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia); Marmitt, G. G. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia); Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Finkelstein, Y. [Nuclear Research Center — Negev, Beer-Sheva 84190 (Israel); Moreh, R. [Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)


    Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.

  10. Calculation of the Doppler broadening function using Fourier analysis;Calculo da funcao de alargamento Doppler utilizando analise de Fourier

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Alessandro da Cruz


    An efficient and precise method for calculation of Doppler broadening function is very important to obtain average group microscopic cross sections, self shielding factors, resonance integrals and others reactor physics parameter. In this thesis two different methods for calculation of Doppler broadening function and interference term will be presented. The main method is based on a new integral form for Doppler broadening function {psi}(x,{zeta}) which gives a mathematical interpretation of the approximation proposed by Bethe and Placzek, as the convolution of the Lorentzian function with a Gaussian function. This interpretation besides leading to a new integral form for {psi}(x,{zeta}), enables to obtain a simple analytic solution for the Doppler broadening function. (author)

  11. Microparticles generated by decompression stress cause central nervous system injury manifested as neurohypophysial terminal action potential broadening


    Yang, Ming; Kosterin, Paul; Salzberg, Brian M.; Milovanova, Tatyana N.; Bhopale, Veena M.; Thom, Stephen R.


    The study goal was to use membrane voltage changes during neurohypophysial action potential (AP) propagation as an index of nerve function to evaluate the role that circulating microparticles (MPs) play in causing central nervous system injury in response to decompression stress in a murine model. Mice studied 1 h following decompression from 790 kPa air pressure for 2 h exhibit a 45% broadening of the neurohypophysial AP. Broadening did not occur if mice were injected with the MP lytic agent...

  12. Broadening engineering education: bringing the community in : commentary on "social responsibility in French engineering education: a historical and sociological analysis". (United States)

    Conlon, Eddie


    Two issues of particular interest in the Irish context are (1) the motivation for broadening engineering education to include the humanities, and an emphasis on social responsibility and (2) the process by which broadening can take place. Greater community engagement, arising from a socially-driven model of engineering education, is necessary if engineering practice is to move beyond its present captivity by corporate interests.

  13. Influence of velocity effects on the shape of N2 (and air) broadened H2O lines revisited with classical molecular dynamics simulations (United States)

    Ngo, N. H.; Tran, H.; Gamache, R. R.; Bermejo, D.; Domenech, J.-L.


    The modeling of the shape of H2O lines perturbed by N2 (and air) using the Keilson-Storer (KS) kernel for collision-induced velocity changes is revisited with classical molecular dynamics simulations (CMDS). The latter have been performed for a large number of molecules starting from intermolecular-potential surfaces. Contrary to the assumption made in a previous study [H. Tran, D. Bermejo, J.-L. Domenech, P. Joubert, R. R. Gamache, and J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transf. 108, 126 (2007)], 10.1016/j.jqsrt.2007.03.009, the results of these CMDS show that the velocity-orientation and -modulus changes statistically occur at the same time scale. This validates the use of a single memory parameter in the Keilson-Storer kernel to describe both the velocity-orientation and -modulus changes. The CMDS results also show that velocity- and rotational state-changing collisions are statistically partially correlated. A partially correlated speed-dependent Keilson-Storer model has thus been used to describe the line-shape. For this, the velocity changes KS kernel parameters have been directly determined from CMDS, while the speed-dependent broadening and shifting coefficients have been calculated with a semi-classical approach. Comparisons between calculated spectra and measurements of several lines of H2O broadened by N2 (and air) in the ν3 and 2ν1 + ν2 + ν3 bands for a wide range of pressure show very satisfactory agreement. The evolution of non-Voigt effects from Doppler to collisional regimes is also presented and discussed.

  14. On the Origin of the Scatter Broadening of Fast Radio Burst Pulses and Astrophysical Implications (United States)

    Xu, Siyao; Zhang, Bing


    Fast radio bursts (FRBs) have been identified as extragalactic sources that can probe turbulence in the intergalactic medium (IGM) and their host galaxies. To account for the observed millisecond pulses caused by scatter broadening, we examine a variety of possible electron density fluctuation models in both the IGM and the host galaxy medium. We find that a short-wave-dominated power-law spectrum of density, which may arise in highly supersonic turbulence with pronounced local dense structures of shock-compressed gas in the host interstellar medium (ISM), can produce the required density enhancements at sufficiently small scales to interpret the scattering timescale of FRBs. This implies that an FRB residing in a galaxy with efficient star formation in action tends to have a broadened pulse. The scaling of the scattering time with the dispersion measure (DM) in the host galaxy varies in different turbulence and scattering regimes. The host galaxy can be the major origin of scatter broadening, but contributes to a small fraction of the total DM. We also find that the sheet-like structure of the density in the host ISM associated with folded magnetic fields in a viscosity-dominated regime of magnetohydrodynamic (MHD) turbulence cannot give rise to strong scattering. Furthermore, valuable insights into the IGM turbulence concerning the detailed spatial structure of density and magnetic field can be gained from the observed scattering timescale of FRBs. Our results favor the suppression of micro-plasma instabilities and the validity of the collisional-MHD description of turbulence properties in the collisionless IGM.

  15. Band Bending in Conjugated Polymer Films: Role of Morphology and Implications for Bulk Charge Transport Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Green, Peter [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wenderott, J. K. [University of Michigan; Dong, Ban Xuan [University of Michigan


    The performance of power conversion devices is impacted by the energy level alignment at the interface between the conjugated polymer and conductive substrate. While band bending has been known to vary between conjugated polymers, we show that the degree of band bending within the same polymer can be just as significant with morphology change. Specifically, a significant band bending effect, studied via Kelvin probe force microscopy (KPFM), was exhibited by poly(3-hexylthiophene) (P3HT) films fabricated using matrix assisted pulsed laser evaporation (MAPLE) in contrast to the conventional spin-cast P3HT films. This finding is associated with a broadening of the density of states (DOS) in the MAPLE-deposited P3HT films, originating from the more disordered structure of the film. These findings, to the best of our knowledge, illustrate for the first time a strong connection between morphology, energy level alignment, and bulk transport in conjugated polymer films.

  16. Cluster banding heat source model

    Institute of Scientific and Technical Information of China (English)

    Zhang Liguo; Ji Shude; Yang Jianguo; Fang Hongyuan; Li Yafan


    Concept of cluster banding heat source model is put forward for the problem of overmany increment steps in the process of numerical simulation of large welding structures, and expression of cluster banding heat source model is deduced based on energy conservation law.Because the expression of cluster banding heat source model deduced is suitable for random weld width, quantitative analysis of welding stress field for large welding structures which have regular welds can be made quickly.

  17. Theoretical Simulation for Identical Bands

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-Jing; CHEN Yong-Shou; GAO Zao-Chun


    @@ The frequency of occurrence of identical bands is studied by analysing a large number of rotational bands calculated with the reflection asymmetric shell model, and the statistical properties of identical bands indicated in all the experimental observations are reproduced within the mean field approximation and beyond mean field treatment, such as angular momentum projection. The distributions of the calculated J(2), Eγ and the fractional change of J(2) are discussed.

  18. Microparticles generated by decompression stress cause central nervous system injury manifested as neurohypophysial terminal action potential broadening. (United States)

    Yang, Ming; Kosterin, Paul; Salzberg, Brian M; Milovanova, Tatyana N; Bhopale, Veena M; Thom, Stephen R


    The study goal was to use membrane voltage changes during neurohypophysial action potential (AP) propagation as an index of nerve function to evaluate the role that circulating microparticles (MPs) play in causing central nervous system injury in response to decompression stress in a murine model. Mice studied 1 h following decompression from 790 kPa air pressure for 2 h exhibit a 45% broadening of the neurohypophysial AP. Broadening did not occur if mice were injected with the MP lytic agent polyethylene glycol telomere B immediately after decompression, were rendered thrombocytopenic, or were treated with an inhibitor of nitric oxide synthase-2 (iNOS) prior to decompression, or in knockout (KO) mice lacking myeloperoxidase or iNOS. If MPs were harvested from control (no decompression) mice and injected into naive mice, no AP broadening occurred, but AP broadening was observed with injections of equal numbers of MPs from either wild-type or iNOS KO mice subjected to decompression stress. Although not required for AP broadening, MPs from decompressed mice, but not control mice, exhibit NADPH oxidase activation. We conclude that inherent differences in MPs from decompressed mice, rather than elevated MPs numbers, mediate neurological injury and that a component of the perivascular response to MPs involves iNOS. Additional study is needed to determine the mechanism of AP broadening and also mechanisms for MP generation associated with exposure to elevated gas pressure.

  19. Broadening of a spectrum line by finite spectrometer resolution. [FORTRAN IV; SAL, KAL

    Energy Technology Data Exchange (ETDEWEB)

    Engleman, R. Jr.


    The distortion of a spectrum line by the finite resolving power of a spectrometer is discussed in terms of a mathematical model. Particular attention is given to the case where either a Gaussian or Cauchy slit function broadens an isolated Doppler, Lorentz, or Voigt absorption line. Corrections to the peak absorption, the line width, and the integrated absorption coefficient are calculated and discussed for different combinations of slit functions and line shapes. Several new series expansions for the corrections are derived. Two general FORTRAN IV programs that calculate these corrections are described and some sample correction curves are given. 27 references.

  20. Characterization of film surface treated with ECR plasma by Doppler broadening

    CERN Document Server

    Nishijima, S; Hirata, K; Kobayashi, Y; Honda, Y; Tagawa, S


    Doppler broadened positron annihilation measurements were carried out using the positron beam technique on plasma treated polyethylene films as a function of incident positron energy. In addition, surface properties of the treated films also have been measured using other conventional techniques such as FT-IR, SEM and AFM. The surface tension of the films was also determined using sessile drop method. The S-parameter is seen to decrease on the surface upon plasma treatment that introduces polar groups such as hydroxyl and carbonyl on the surface. The results are discussed.

  1. A revised uncertainty budget for measuring the Boltzmann constant using the Doppler Broadening Technique on ammonia

    CERN Document Server

    Lemarchand, Cyril; Sow, Papa Lat Tabara; Triki, Meriam; Tokunaga, Sean K; Briaudeau, Stephan; Chardonnet, Christian; Darquié, Benoît; Daussy, Christophe


    We report on our on-going effort to measure the Boltzmann constant, kB, using the Doppler Broadening Technique. The main systematic effects affecting the measurement are discussed. A revised error budget is presented in which the global uncertainty on systematic effects is reduced to 2.3 ppm. This corresponds to a reduction of more than one order of magnitude compared to our previous Boltzmann constant measurement. Means to reach a determination of kB at the part per million accuracy level are outlined.

  2. Doppler broadening of in-flight positron annihilation radiation due to electron momentum. (United States)

    Hunt, A W; Cassidy, D B; Sterne, P A; Cowan, T E; Howell, R H; Lynn, K G; Golevchenko, J A


    We report the first observation of electron momentum contributions to the Doppler broadening of radiation produced by in-flight two-photon annihilation in solids. In these experiments an approximately 2.5 MeV positron beam impinged on thin polyethylene, aluminum, and gold targets. Since energetic positrons easily penetrate the nuclear Coulomb potential and do not cause a strong charge polarization, the experimental annihilation line shapes agree well with calculations based on a simple independent-particle model. Moreover, annihilations with the deepest core electrons are greatly enhanced.

  3. Stretchable polymeric modulator for intracavity spectroscopic broadening of femtosecond optical parametric oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yimeng; Zhang, Xinping, E-mail:; Zhang, Jian; Liu, Hongmei [Institute of Information Photonics Technology and College of Applied Sciences, Beijing University of Technology, Beijing 100124 (China)


    We investigate stretching-induced microscopic deformations spatially distributed in a flexible plate of polydimethylsiloxane (PDMS) and their applications in the broadening of the output spectrum of a femtosecond optical parametric oscillator. The hologram of the stretched PDMS plate was used to evaluate indirectly the microscopic deformations. The experimental results show that these deformations exhibit weak scattering and diffraction of light and induce negligible cavity loss, ensuring practical applications of the PDMS plate as an intracavity device for lasers. In combination with the thickness reduction of the PDMS plate through stretching, the distributed deformations enable smooth tuning of the output spectrum.

  4. Kramers-Kronig relation in a Doppler-broadened Λ-type three-level system (United States)

    Wang, Meng; Lu, Xiao-Gang; Bai, Jin-Hai; Pei, Li-Ya; Miao, Xing-Xu; Gao, Yan-Lei; Wu, Ling-An; Fu, Pan-Ming; Yang, Shi-Ping; Pang, Zhao-Guang; Wang, Ru-Quan; Zuo, Zhan-Chun


    We measure the absorption and dispersion in a Doppler-broadened Λ-type three level system by resonant stimulated Raman spectroscopy with homodyne detection. Through studying the dressed state energies of the system, it is found that the absorption and dispersion satisfy the Kramers-Kronig relation. The absorption and dispersion spectra calculated by employing this relation agree well with our experimental observations. Project supported by the National Basic Research Program of China (Grant Nos. 2013CB922002 and 2010CB922904), the National Natural Science Foundation of China (Grant Nos. 11274376 and 61308011), and the Natural Science Foundation of Hebei Province, China (Grant No. A2015205161).

  5. Absorption properties of a driven Doppler-broadened ladder system with hyperfine structure

    Institute of Scientific and Technical Information of China (English)

    吴金辉; 高锦岳


    We have studied the absorption spectrum of a Doppler-broadened ladder system, where the highest level is coupled into two middle hyperfine sublevels by a strong coherent field. We find that, when the system is considered as homoge- neous, either two or three spectral components are observed, depending on the detuning of the coherent field. But when the velocity distribution of atoms is considered, we can always observe one electromagnetically induced transparency (EIT) window with high dispersion. So the atomic hyperfine structure cannot be an impediment for obtaining EIT.

  6. Scatter broadening of pulsars and implications on the interstellar medium turbulence

    CERN Document Server

    Xu, Siyao


    Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of electron density fluctuations consisting of not only a Kolmogorov density spectrum but also a short-wave-dominated density spectrum with the density structure formed at small scales due to shocks. The resulting dependence of the scatter broadening time on the dispersion measure (DM) naturally interprets the existing observational data for both low and high-DM pulsars. According to the criteria that we derive for a quantitative determination of scattering regimes over wide ranges of DMs and frequencies $\

  7. Iliotibial band Z-lengthening. (United States)

    Richards, David P; Alan Barber, F; Troop, Randal L


    Iliotibial band friction syndrome (ITBFS) is a common overuse injury reported to afflict 1.6% to 12% of runners. It results from an inflammatory response secondary to excessive friction that occurs between the lateral femoral epicondyle and the iliotibial band. Initial treatments include rest, anti-inflammatory medication, modalities (ice or heat), stretching, physical therapy, and possibly a cortisone injection. In recalcitrant cases of ITBFS, surgery has been advocated. This report describes a surgical technique of Z-lengthening of the iliotibial band in patients presenting with lateral knee pain localized to the iliotibial band at the lateral femoral epicondyle and Gerdy's tubercle who failed all nonoperative efforts.

  8. Scarless platysmaplasty for platysmal bands

    Directory of Open Access Journals (Sweden)

    Shiffman Melvin


    Full Text Available Transection of plastysmal bands has required a surgical approach that leaves scars and limits patient activities for a period of time. The author has developed a simple method to transect the platysmal bands under local anesthesia without resorting to skin incisions. The transection is performed with the use of a Vicryl ® suture that is inserted through the skin, around the platysmal band, and then out through the original entry point. A back and forth motion of the suture cuts through the band.

  9. Band calculation of lonsdaleite Ge (United States)

    Chen, Pin-Shiang; Fan, Sheng-Ting; Lan, Huang-Siang; Liu, Chee Wee


    The band structure of Ge in the lonsdaleite phase is calculated using first principles. Lonsdaleite Ge has a direct band gap at the Γ point. For the conduction band, the Γ valley is anisotropic with the low transverse effective mass on the hexagonal plane and the large longitudinal effective mass along the c axis. For the valence band, both heavy-hole and light-hole effective masses are anisotropic at the Γ point. The in-plane electron effective mass also becomes anisotropic under uniaxial tensile strain. The strain response of the heavy-hole mass is opposite to the light hole.

  10. Garage Band or GarageBand[R]? Remixing Musical Futures (United States)

    Vakeva, Lauri


    In this paper, I suggest that it is perhaps time to consider the pedagogy of popular music in more extensive terms than conventional rock band practices have to offer. One direction in which this might lead is the expansion of the informal pedagogy based on a "garage band" model to encompass various modes of digital artistry wherever this artistry…

  11. Global wild annual Lens collection: a potential resource for lentil genetic base broadening and yield enhancement.

    Directory of Open Access Journals (Sweden)

    Mohar Singh

    Full Text Available Crop wild relatives (CWRs are invaluable gene sources for various traits of interest, yet these potential resources are themselves increasingly threatened by the impact of climate change as well as other anthropogenic and socio-economic factors. The prime goal of our research was to cover all aspects of wild Lens genetic resource management like species characterization, agro-morphological evaluation, diversity assessment, and development of representative sets for its enhanced utilization in lentil base broadening and yield improvement initiatives. We characterized and evaluated extensively, the global wild annual Lens taxa, originating from twenty seven counties under two agro-climatic conditions of India consecutively for three cropping seasons. Results on various qualitative and quantitative characters including two foliar diseases showed wide variations for almost all yield attributing traits including multiple disease resistance in the wild species, L. nigricans and L. ervoides accessions. The core set developed from the entire Lens taxa had maximum representation from Turkey and Syria, indicating rich diversity in accessions originating from these regions. Diversity analysis also indicated wide geographical variations across genepool as was reflected in the core set. Potential use of core set, as an initial starting material, for genetic base broadening of cultivated lentil was also suggested.

  12. Remembering Collective Violence: Broadening the Notion of Traumatic Memory in Post-Conflict Rehabilitation. (United States)

    Kevers, Ruth; Rober, Peter; Derluyn, Ilse; De Haene, Lucia


    In the aftermath of war and armed conflict, individuals and communities face the challenge of dealing with recollections of violence and atrocity. This article aims to contribute to a better understanding of processes of remembering and forgetting histories of violence in post-conflict communities and to reflect on related implications for trauma rehabilitation in post-conflict settings. Starting from the observation that memory operates at the core of PTSD symptomatology, we more closely explore how this notion of traumatic memory is conceptualized within PTSD-centered research and interventions. Subsequently, we aim to broaden this understanding of traumatic memory and post-trauma care by connecting to findings from social memory studies and transcultural trauma research. Drawing on an analysis of scholarly literature, this analysis develops into a perspective on memory that moves beyond a symptomatic framing toward an understanding of memory that emphasizes its relational, political, moral, and cultural nature. Post-conflict memory is presented as inextricably embedded in communal relations, involving ongoing trade-offs between individual and collective responses to trauma and a complex negotiation of speech and silence. In a concluding discussion, we develop implications of this broadened understanding for post-conflict trauma-focused rehabilitation.

  13. Laser-induced plasma electron number density: Stark broadening method versus the Saha-Boltzmann equation (United States)

    Arnab, Sarkar; Manjeet, Singh


    We report spectroscopic studies on plasma electron number density of laser-induced plasma produced by ns-Nd:YAG laser light pulses on an aluminum sample in air at atmospheric pressure. The effect of different laser energy and the effect of different laser wavelengths were compared. The experimentally observed line profiles of neutral aluminum have been used to extract the excitation temperature using the Boltzmann plot method, whereas the electron number density has been determined from the Stark broadened as well as using the Saha-Boltzmann equation (SBE). Each approach was also carried out by using the Al emission line and Mg emission lines. It was observed that the SBE method generated a little higher electron number density value than the Stark broadening method, but within the experimental uncertainty range. Comparisons of N e determined by the two methods show the presence of a linear relation which is independent of laser energy or laser wavelength. These results show the applicability of the SBE method for N e determination, especially when the system does not have any pure emission lines whose electron impact factor is known. Also use of Mg lines gives superior results than Al lines.

  14. Power regulating range broadening of the WWER-type reactor power units

    Energy Technology Data Exchange (ETDEWEB)

    Dement' ev, B.A.; Petrov, V.A.; Proskuryakov, A.G.; Puchkov, V.V. (Moskovskij Ehnergeticheskij Inst. (USSR))


    Calculational studies on the use of sliding pressure (SP) regime to expand the regulating range of the WWER-440 reactor power units are presented. Two operation regimes of a power unit have been considered: according to weekly and daily load swings in electrical grids. The conclusion is made that the use of SP regime in the secondary circuit improves manoeuvable characterstics of the power unit in the second half of operating cycle. T of the reactor (0.6 broadening of the reactor. Besides, the use of SP regime during power unit operation with decreased loadings is the more efficient the smaller is the load. The range of operating cycle 0.8 <= T <= 1 makes the greatest contribution to regulating range broadening as a result of SP regime use. Conclusions of the calculational studies can be also applied to WWER reactors of other types as well as to RBMK reactors.

  15. Inversionless gain enhancing due to Doppler broadening in a closed lambda-type system

    Institute of Scientific and Technical Information of China (English)


    An analysis is made of the effect of Doppler broadening on gain without inversion (GWI) from different aspects in a closed lambda-type three-level system with an incoherent pump. It is shown that, regardless of the driving field being on resonance or not, for the counter- or co-propagating of the probe and driving fields (PDF), GWI does not monotonically decrease or increase with increasing Doppler width. Except for the case of counter-propagating PDF with off-resonance driving field, at a suitable Doppler width one can obtain a gain maximum value much larger than that without Doppler broadening; especially in the situation of the resonant driving field, the co-propagating geometry leads to a larger GWI. In addition, for the counter-propagating geometry, when Doppler width is larger enough, GWI oscillation occurs, and the oscillation amplitude and region increase with increasing Doppler width. These conclusions are very different from that obtained in previous investigation (Lukin et al, Laser Phys. 6 436 (1996)).

  16. Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic Turbulence and Tangled Molecular Clouds

    CERN Document Server

    Hacar, A; Burkert, A; Goldsmith, P


    (Abridged) Many of the observed CO line profiles exhibit broad linewidths that greatly exceed the thermal broadening expected within molecular clouds. These suprathermal CO linewidths are assumed to be originated from the presence of unresolved supersonic motions inside clouds. Typically overlooked in the literature, in this paper we aim to quantify the impact of the opacity broadening effects on the current interpretation of the CO suprathermal line profiles. Without any additional contributions to the gas velocity field, a large fraction of the apparently supersonic (${\\cal M}\\sim$2-3) linewidths measured in both $^{12}$CO and $^{13}$CO (J=1-0) lines can be explained by the saturation of their corresponding sonic-like, optically-thin C$^{18}$O counterparts assuming standard isotopic fractionation. Combined with the presence of multiple components detected in our C$^{18}$O spectra, these opacity effects seem to be also responsible of the highly supersonic linewidths (${\\cal M}>$8-10) detected in the broadest...

  17. Practical Model for First Hyperpolarizability Dispersion Accounting for Both Homogeneous and Inhomogeneous Broadening Effects. (United States)

    Campo, Jochen; Wenseleers, Wim; Hales, Joel M; Makarov, Nikolay S; Perry, Joseph W


    A practical yet accurate dispersion model for the molecular first hyperpolarizability β is presented, incorporating both homogeneous and inhomogeneous line broadening because these affect the β dispersion differently, even if they are indistinguishable in linear absorption. Consequently, combining the absorption spectrum with one free shape-determining parameter Ginhom, the inhomogeneous line width, turns out to be necessary and sufficient to obtain a reliable description of the β dispersion, requiring no information on the homogeneous (including vibronic) and inhomogeneous line broadening mechanisms involved, providing an ideal model for practical use in extrapolating experimental nonlinear optical (NLO) data. The model is applied to the efficient NLO chromophore picolinium quinodimethane, yielding an excellent fit of the two-photon resonant wavelength-dependent data and a dependable static value β0 = 316 × 10(-30) esu. Furthermore, we show that including a second electronic excited state in the model does yield an improved description of the NLO data at shorter wavelengths but has only limited influence on β0.

  18. Pulse-driven nonlinear Alfv\\'en waves and their role in the spectral line broadening

    CERN Document Server

    Chmielewski, P; Murawski, K; Musielak, Z E


    We study the impulsively generated non-linear Alfv\\'en waves in the solar atmosphere, and describe their most likely role in the observed non-thermal broadening of some spectral lines in solar coronal holes. We solve numerically the time-dependent magnetohydrodynamic equations to find temporal signatures of large-amplitude Alfv\\'en waves in the model atmosphere of open and expanding magnetic field configuration, with a realistic temperature distribution. We calculate the temporally and spatially averaged, instantaneous transversal velocity of non-linear Alfv\\'en waves at different heights of the model atmosphere, and estimate its contribution to the unresolved non-thermal motions caused by the waves. We find that the pulse-driven nonlinear Alfv\\'en waves with the amplitude $A_{\\rm v}$=50 km s$^{-1}$ are the most likely candidates for the non-thermal broadening of Si VIII $\\lambda$1445.75 \\AA\\ line profiles in the polar coronal hole as reported by Banerjee et al. (1998). We also demonstrate that the Alfv\\'en w...

  19. Doppler Shifts and Broadening and the Structure of the X-ray Emission from Algol

    CERN Document Server

    Chung, S M; Kashyap, V L; Lin, L W; Ratzlaff, P W; Chung, Sun Mi; Drake, Jeremy J.; Kashyap, Vinay L.; Lin, Li Wei; Ratzlaff, Peter W.


    In a study of Chandra High Energy Transmission Grating spectra of Algol, we clearly detect Doppler shifts caused by the orbital motion of Algol B. These data provide the first definitive proof that the X-ray emission of Algol is dominated by the secondary, in concordance with expectations that Algol A (B8) is X-ray dark. The measured Doppler shifts are slightly smaller than expected, implying an effective orbital radius of about 10 Rsolar, instead of 11.5 Rsolar for the Algol B center of mass. This could be caused by a small contribution of X-ray flux from Algol A (10-15%), possibly through accretion. The more likely explanation is an asymmetric corona biased toward the system center of mass by the tidal distortion of the surface of Algol B. Analysis of the strongest lines indicates excess line broadening of ~150 km/s above that expected from thermal motion and surface rotation. Possible explanations include turbulence, flows or explosive events, or rotational broadening from a radially extended corona. We fa...

  20. High frequency VLBI observations of the scatter broadened quasar B2005+403

    CERN Document Server

    Gabanyi, K E; Britzen, S; Krichbaum, T P; Ros, E; Witzel, A; Zensus, J A


    The quasar B2005+403 located behind the Cygnus region, is a suitable object for studying the interplay between propagation effects, which are extrinsic to the source and source intrinsic variability. On the basis of VLBI experiments performed at 1.6, 5, 8, 15, 22, and 43GHz between 1992-2003 and parallel multi-frequency monitoring of the total flux density, we investigated the variability of total flux density and source structure. Below 8 GHz, the point-like VLBI source is affected by scatter-broadening of the turbulent interstellar medium, which is located along the line of sight and likely associated with the Cygnus region. We present and discuss the measured frequency dependence of the source size, which shows a power-law with slope of -1.91+/-0.05. From the measured scattering angle at 1GHz of 77.1+/-4.0mas a SM=0.43+/-0.04 m^{-20/3} kpc is derived, consistent with the general properties of the ISM in this direction. The decreasing effect of angular broadening towards higher frequencies allows to study t...

  1. Collisional broadening of Mg, Sr, Ca and Na resonance lines by atomic hydrogen (United States)

    Kerkeni, B.; Barklem, P. S.; Spielfiedel, A.; Feautrier, N.


    This paper compares different approaches used in the calculation of the broadening of spectral lines by H-atom collisions. Firstly, the validity of the semi-classical approach for the collision versus the quantum one is discussed. It is shown that, at the temperatures typical of stellar atmospheres (from 3000 to 10 000 K), a classical approach (with the advantage of reduced computation times) is sufficient. The dependence of the broadening constants on interatomic potentials is also studied. Two different approaches were used to derive these potentials: in the first approach, the interaction energy is determined by the usual methods of quantum chemistry. The second approach, developed by Anstee, Barklem and O'Mara (ABO potentials), is based on second-order perturbation theory. In the case of Mg H, a hybrid potential obtained from ab initio values for the short distances and from the perturbation method in the asymptotic region was also tested. The results for the Na resonance line show that even significant differences in the potentials lead to relatively small changes in the calculated widths. From the comparison of the results for the Mg, Sr and Ca resonance lines, it appears that ABO potentials give results of the order of 8 20% smaller than results from ab initio and hybrid potentials. This difference is attributed to the presence of an avoided ionic crossing in the upper singlet Sgr states that coincides roughly with the Weisskopf radius.

  2. Photo-induced brightening and broadening effects of gold quantum clusters (United States)

    Huang, Hsiu-Ying; Lin, Chia-Hui; Lin, Cheng-An J.


    We describe the use of UV light under different radiation time induces a variety of fluorescence wavelength of gold quantum clusters. First, we synthesize blue-emitted gold quantum clusters by dissolving the gold trichloride in pure toluene. To simplify the expression, we assume that the several featured PL peak (425, 450, 470 nm) is the signal for blue-emitted gold quantum clusters. Undergo UV irradiation can brighten and broaden the PL spectra of gold quantum clusters, which are observed by the evolutional spectra versus exposure time. After UV light exposure, the major population of gold quantum clusters @425nm decreased and turned to gold quantum clusters@450nm, followed by the growing population of gold quantum clusters@470nm clusters. Until 2 hour exposure, the spectra become broad with major peak shifted to 525 nm. The tunable spectra from blue to green attributes to the induced growth of gold quantum clusters by UV irradiation. The UV energy indeed tunes and broadens the emission covering the whole visible-spectra range. Finally, we also utilize via proper selection of organic surfactant (such as: trioctyl phosphine, TOP) can coordinate the quantum yield enhancement of blue-emitted gold quantum clusters under UV irradiation. The experiment method is easily for gold quantum clusters synthesis. Thus we expect this materials can be developed for fluorescence labeling application in the future.

  3. Plasma density characterization at SPARC-LAB through Stark broadening of Hydrogen spectral lines

    Energy Technology Data Exchange (ETDEWEB)

    Filippi, F., E-mail: [Dipartimento di Scienze di Base e Applicate per l' Ingegneria (SBAI), ‘Sapienza’ Università di Roma, Via A. Scarpa 14-16, 00161 Roma (Italy); INFN-Roma1, Piazzale Aldo Moro, 2 00161 Roma (Italy); Anania, M.P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Cianchi, A. [Dipartimento di Fisica, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma (Italy); Di Giovenale, D.; Di Pirro, G.; Ferrario, M. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Mostacci, A.; Palumbo, L. [Dipartimento di Scienze di Base e Applicate per l' Ingegneria (SBAI), ‘Sapienza’ Università di Roma, Via A. Scarpa 14-16, 00161 Roma (Italy); INFN-Roma1, Piazzale Aldo Moro, 2 00161 Roma (Italy); Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F. [Laboratori Nazionali di Frascati, INFN, Via E. Fermi, Frascati (Italy); Zigler, A. [Hebrew University of Jerusalem, Jerusalem 91904 (Israel)


    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC-LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC-LAB is presented. - Highlights: • Stark broadening of Hydrogen lines has been measured to determine plasma density. • Plasma density diagnostic tool for plasma-based experiments at SPARC-LAB is presented. • Plasma density in tapered laser triggered ablative capillary discharge was measured. • Results of plasma density measurements in ablative capillaries are shown.

  4. Characterization of an Experimental Referee Broadened Specification (ERBS) aviation turbine fuel and ERBS fuel blends (United States)

    Seng, G. T.


    Characterization data and comparisons of these data are presented for three individual lots of a research test fuel designated as an Experimental Referee Broadened Specification (ERBS) aviation turbine fuel. This research fuel, which is a blend of kerosene and hydrotreated catalytic gas oil, is a representation of a kerojet fuel with broadened properties. To lower the hydrogen content of the ERBS fuel, a blending stock, composed of xylene bottoms and hydrotreated catalytic gas oil, was developed and employed to produce two different ERBS fuel blends. The ERBS fuel blends and the blending stock were also characterized and the results for the blends are compared to those of the original ERBS fuel. The characterization results indicate that with the exception of the freezing point for ERBS lot 2, which was slightly high, the three lots, produced over a 2 year period, met all general fuel requirements. However, although the properties of the fuels were found to be fairly consistent, there were differences in composition. Similarly, all major requirements for the ERBS fuel blends were met or closely approached, and the properties of the blended fuels were found to generally reflect those expected for the proportions of ERBS fuel and blending stock used in their production.

  5. The rotational broadening of V395 Car - implications on compact object's mass

    CERN Document Server

    Shahbaz, T


    CONTEXT: The masses previously obtained for the X-ray binary 2S0921-630 inferred a compact object that was either a high-mass neutron star or low-mass black-hole, but used a previously published value for the rotational broadening (vsini) with large uncertainties. AIMS: We aim to determine an accurate mass for the compact object through an improved measurement of the secondary star's projected equatorial rotational velocity. METHODS: We have used UVES echelle spectroscopy to determine the vsini of the secondary star (V395 Car) in the low-mass X-ray binary 2S0921-630 by comparison to an artificially broadened spectral-type template star. In addition, we have also measured vsini from a single high signal-to-noise ratio absorption line profile calculated using the method of Least-Squares Deconvolution (LSD). RESULTS: We determine vsini to lie between 31.3+/-0.5km/s to 34.7+/-0.5km/s (assuming zero and continuum limb darkening, respectively) in disagreement with revious results based on intermediate resolution sp...

  6. Long Lake banding project, 1965 (United States)

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the results of a banding project on Long Lake in 1965. The dates at the banding site were July 27th through August 8th. As in the past, the...


    Directory of Open Access Journals (Sweden)

    V. S. Alekhin


    Full Text Available Objectives. Experimental and theoretical determination of dependencies of strength characteristics of bored micropiles with a pedestal formed by rammed rubble on: casing diameter, fraction, and volume of crushed stone for collapsing macroporous clays. Method. Laboratory and field experiments were carried out; numerical calculations in two-dimensional and threedimensional arrangement for the determination of strain-stress analysis of the foundation using a MIDAS GTS_NX software system, implementing the finite element method and developed for complex geotechnical problems; some recommendations for implementation are provided. Results The dependence of the load-bearing capacity of bored micropiles on a broadened base of rammed aggregate with vertical loading is determined. At the maximum broadening diameter of 3.5 of the micropiles shaft the load-bearing capacity of the subsoil is increased by between 1.8 and 6 times compared with micropiles without broadening depending on the diameter of the pile shaft. During the experimental and numerical studies of the dependencies of deformation-strength parameters of the deep foundation works consisting of a bored micropile with a broadened base, namely the pile diameter, aggregate particle size and volume, seal diameter of the subsoil soil half-space, as well as the development of the theory of formation of the end broadening geometry of rammed aggregate in the form of an ellipsoid of revolution were established. Conclusion The full-scale measurements of the broadening of bored micropiles showed that their shape is close to an ellipsoid of revolution, and the ratio of semi-axes is directly dependent on the characteristics of soil and gravel volume, which was taken into account in the construction of the finite element model in the numerical simulation experiment.The results of numerical studies of the bored micropile loading with broadened base on the MIDAS GTS show good agreement with the results of the

  8. Miniaturized ultra-high performance liquid chromatography coupled to electrochemical detection: Investigation of system performance for neurochemical analysis. (United States)

    Van Schoors, Jolien; Maes, Katrien; Van Wanseele, Yannick; Broeckhoven, Ken; Van Eeckhaut, Ann


    The interest in implementation of miniaturized ultra-high performance liquid chromatography (UHPLC) in neurochemical research is growing because of the need for faster, more selective and more sensitive neurotransmitter analyses. The instrument performance of a tailor designed microbore UHPLC system coupled to electrochemical detection (ECD) is investigated, focusing on the quantitative monoamine determination in in vivo microdialysis samples. The use of a microbore column (1.0mm I.D.) requires miniaturization of the entire instrument, though a balance between extra-column band broadening and injection volume must be considered. This is accomplished through the user defined Performance Optimizing Injection Sequence, whereby 5 μL sample is injected on the column with a measured extra-column variance of 4.5-9.0 μL(2) and only 7 μL sample uptake. Different sub-2 μm and superficially porous particle stationary phases are compared by means of the kinetic plot approach. Peak efficiencies of about 16000-35000 theoretical plates are obtained for the Acquity UPLC BEH C18 column within 13 min analysis time. Furthermore, the coupling to ECD is shown suitable for microbore UHPLC analysis thanks to the miniaturized flow cell design, sufficiently fast data acquisition and mathematical data filtering. Ultimately, injection of in vivo samples demonstrates the applicability of the system for microdialysis analysis.

  9. Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

    CERN Document Server

    Smith, Anthony J; Cross, Nicholas J G


    We present luminosity and surface brightness distributions of 36,663 galaxies with K-band photometry from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimation of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best fitting Schechter function parameters for the K-band luminosity function are found to be M*-5log h=-23.17 +/- 0.04, alpha=-0.8...

  10. A Large-Area Transferable Wide Band Gap 2D Silicon Dioxide Layer. (United States)

    Büchner, Christin; Wang, Zhu-Jun; Burson, Kristen M; Willinger, Marc-Georg; Heyde, Markus; Schlögl, Robert; Freund, Hans-Joachim


    An atomically smooth silica bilayer is transferred from the growth substrate to a new support via mechanical exfoliation at millimeter scale. The atomic structure and morphology are maintained perfectly throughout the process. A simple heating treatment results in complete removal of the transfer medium. Low-energy electron diffraction, Auger electron spectroscopy, scanning tunneling microscopy, and environmental scanning electron microscopy show the success of the transfer steps. Excellent chemical and thermal stability result from the absence of dangling bonds in the film structure. By adding this wide band gap oxide to the toolbox of 2D materials, possibilities for van der Waals heterostructures will be broadened significantly.

  11. Dilute RKKY model for NMR line broadening in the hidden-order state of URu2Si2 (United States)

    Walstedt, R. E.; Kambe, S.; Tokunaga, Y.; Sakai, H.


    A well-known analytic model for Lorentzian broadening of metallic NMR lines by dilute localized magnetic centers embedded in a lattice has been applied to the case of the twofold-symmetry magnetism in URu2Si2 reported by R. Okazaki et al. [Science 331, 439 (2011), 10.1126/science.1197358]. The observed Lorentzian spectra are accounted for with a simple formula giving the 29Si NMR linewidth in terms of the susceptibility of the magnetic-broadening centers and a Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling parameter. The concentration of such centers is estimated as c ˜0.01 . A numerical simulation of these effects confirms Lorentzian broadening with no measurable NMR shift and a width in reasonable agreement with the analytical model. The simulation shows further that domain effects on these spectra are largely absent. A four-site extended model of the broadening centers gives an estimate of the twofold susceptibility within a factor of 2 of the torque value of the susceptibility. Hypothetical superlattice effects are shown to be easily smoothed over by convolution with background Lorentzian broadening.

  12. Line broadening of excimers bound to the surface of 4He clusters investigated by comparison with corona discharge excitation spectra (United States)

    Mendoza-Luna, Luis Guillermo; Watkins, Mark; von Haeften, Klaus; Bonifaci, Nelly; Aitken, Frederic


    A new method for assessing the site-specific emission from electronically excited helium droplets is presented. The fluorescence features of helium droplets show sharp rotationally resolved lines indicating desorption of excimers and emission far outside the droplets as well as blue-shifted and strongly broadened features due to emission of excimers confined in cavities within the droplets. A third feature is identified: slightly broadened rotational lines that we attribute to emission from excimers bound to the droplet surface. The line broadening arises from collisions with the helium gas within the surface layer of the helium droplets. These conditions are simulated using a high pressure gas cell in which helium gas is electronically excited using a corona discharge. Rotational line broadening of similar magnitude to that of large droplets (N ˜ 107 atoms) is observed for gas pressures at about 5 bar and 80 K, corresponding to a number density of 4.52 × 10-4 Å-3. We conclude that the excimers are located within a shell separated by 6 to 7 Å from the radius where the density has dropped to 50% of its centre value. Helium droplets that are smaller (N ˜ 104 atoms) exhibit rotational lines that are less broadened, which we attribute to the superposition of features originating from desorbed and from surface-bound excimers. A fit of the linewidths reveals that around 50% of the excimers are bound to the surface of the smaller droplets.

  13. Microstrip microwave band gap structures

    Indian Academy of Sciences (India)

    V Subramanian


    Microwave band gap structures exhibit certain stop band characteristics based on the periodicity, impedance contrast and effective refractive index contrast. These structures though formed in one-, two- and three-dimensional periodicity, are huge in size. In this paper, microstrip-based microwave band gap structures are formed by removing the substrate material in a periodic manner. This paper also demonstrates that these structures can serve as a non-destructive characterization tool for materials, a duplexor and frequency selective coupler. The paper presents both experimental results and theoretical simulation based on a commercially available finite element methodology for comparison.

  14. Band head spin assignment of superdeformed bands in 86Zr (United States)

    Dadwal, Anshul; Mittal, H. M.


    Two parameter expressions for rotational spectra viz. variable moment of inertia (VMI), ab formula and three parameter Harris ω 2 expansion are used to assign the band head spins (I 0) of four rotational superdeformed bands in 86Zr. The least-squares fitting method is employed to obtain the band head spins of these four bands in the A ∼ 80 mass region. Model parameters are extracted by fitting of intraband γ-ray energies, so as to obtain a minimum root-mean-square (rms) deviation between the calculated and the observed transition energies. The calculated transition energies are found to depend sensitively on the assigned spins. Whenever an accurate band head spin is assigned, the calculated transition energies are in agreement with the experimental transition energies. The dynamic moment of inertia is also extracted and its variation with rotational frequency is investigated. Since a better agreement of band head spin with experimental results is found using the VMI model, it is a more powerful tool than the ab formula and Harris ω 2 expansion.

  15. Anisotropy in the angular broadening of Sgr A$^*$ at the Galactic Center

    CERN Document Server

    Yusef-Zadeh, F; Wardle, M; Melia, F; Roberts, D


    We present the results of a $\\lambda$20 cm VLA observation of the compact Galactic center radio source Sgr A$^*$. The scatter-broadened image is elongated in the East-West direction, with an axial ratio of 0.6$\\pm$0.05 and a position angle of 87$^0\\pm$3$^0$. A similar shape and orientation has been found previously at shorter wavelengths using VLBI and VLBA. Both the major and minor axes follow the $\\lambda^2$ law appropriate for scattering by turbulence in the intervening medium. Assuming that the anisotropy is caused by a magnetic field permeating the scattering medium, we argue that the scattering occurs within extended HII regions lying in the central 100 pc of the Galaxy. The magnetic field in this region must be poloidal, organized and is estimated to have a strength of at least 30 to 100 $\\mu$Gauss.

  16. Inhomogeneous broadening of optical transitions of 87Rb atoms in an optical nanofiber trap

    CERN Document Server

    Lee, J; Hoffman, J E; Orozco, L A; Rolston, S L


    We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produce significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams; weighted by the temperature-dependent position of the atoms in the trap qualitatively describe the observed asymmetric profile, and explained differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.

  17. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening (United States)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.


    Due to the relativistic decrease of the electron cyclotron frequency, a cyclotron resonance may appear between runaway electrons and lower hybrid waves. A single particle description of the runaway dynamics [J. R. Martín-Solís et al., Phys. Plasmas 5, 2370 (1998)] is extended to analyze the effect of the interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening. The conditions under which the resonant interaction can play a role in limiting the runaway energy are established and it is shown that, under typical lower hybrid current drive operation parameters, an efficient wave-particle coupling may occur. Observations of a fast pitch angle scattering event during the current decay phase of Ohmic discharges in the Toroidal Experiment for Technically Oriented Research (TEXTOR) [R. J. E. Jaspers, Ph.D. thesis, Technical University Eindhoven (1995)] are interpreted in terms of such interaction.

  18. Nitride superluminescent diodes with broadened emission spectrum fabricated using laterally patterned substrate. (United States)

    Kafar, A; Stanczyk, S; Sarzynski, M; Grzanka, S; Goss, J; Targowski, G; Nowakowska-Siwinska, A; Suski, T; Perlin, P


    We demonstrate InGaN/GaN superluminescent diodes with broadened emission spectra fabricated on surface-shaped bulk GaN (0001) substrates. The patterning changes the local vicinal angle linearly along the device waveguide, which results in an indium incorporation profile in InGaN quantum wells. The structure was investigated by microphotoluminescence mapping, showing a shift of central emission wavelength from 413 nm to 430 nm. Spectral full width at half maximum of processed superluminescent diodes is equal to 6.1 nm, while the reference chips show 3.4 nm. This approach may open the path for using nitride devices in applications requiring broad emission spectrum and high beam quality, such as optical coherence tomography.

  19. Effect of collisional lines broadening and calibration functions in the pure rotational Raman lidar technique (United States)

    Gerasimov, Vladislav V.; Zuev, Vladimir V.


    We present and examine two three-coefficient calibration functions to be used for the tropospheric temperature retrievals via the pure rotational Raman (PRR) lidar technique. These functions are the special cases of the general analytical calibration function in the PRR lidar technique. The general function special cases take into account the collisional (pressure) broadening of all individual atmospheric N2 and O2 PRR lines in varying degrees. We apply these two special cases to real lidar remote sensing data and compare nighttime temperature profiles retrieved using these calibration functions to the profiles retrieved using other known ones. The absolute statistical uncertainties of temperature retrieval are also given in an analytical form. Lidar measurements data, obtained in Tomsk (56.48° N, 85.05° E, Western Siberia, Russia) using the IMCES PRR lidar at λ = 354.67 nm on 1 April 2015, were used for the tropospheric temperature retrievals (3-12 km).

  20. On the precipitation sequence in a Ni-based superalloy: A Coincidence Doppler Broadening study

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Santos, G. [NIECyT, UNCentro, Pinto 399, B7000GHG Tandil (Argentina); Petkov, M. [Jet Propulsion Lab, California Institute of Technology, Pasadena, CA 91109 (United States); Lynn, K.G. [Department of Physics, Washington State University, Pullman WA 99164-2814 (United States)


    The precipitation sequence at 700 C of the Ni{sub 3}(Ti,Al)-type ordered {gamma}' phase in the commercial nickel-based superalloy Inconel X-750 was investigated using Coincidence Doppler Broadening (CDB) technique. The results obtained are discussed in terms of positron annihilation in two well-defined states: one corresponding to the matrix ({gamma} phase) and a second related to the {gamma}' precipitates. Between these two aging stages, CDB distributions corresponding to selected intermediate aging treatments could be presented exactly, within the experimental scatter, as a linear combination of the {gamma} and {gamma}' signatures. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Plasmonic Nanoparticle-based Hybrid Photosensitizers with Broadened Excitation Profile for Photodynamic Therapy of Cancer Cells (United States)

    Wang, Peng; Tang, Hong; Zhang, Peng


    Photodynamic therapy combining nanotechnology has shown great potential with improved therapeutic efficacy and fewer side effects. Ideal photosensitizers for cancer treatment should both have good singlet oxygen production capability and be excitable by light illuminations with deep tissue penetration. Here we report a type of hybrid photosensitizers consisting of plasmonic silver nanoparticles and photosensitizing molecules, where strong resonance coupling between the two leads to a broadened excitation profile and exceptionally high singlet oxygen production under both visible light and infrared light excitations. Our results indicate that the hybrid photosensitizers display low cytotoxicity without light illumination yet highly enhanced photodynamic inhibition efficacy against Hela cells under a broad spectrum of light illuminations including the near-infrared light, which has great implication in photodynamic therapy of deep-tissue cancers.

  2. Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines (United States)

    Filippi, F.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.


    Plasma-based acceleration techniques are of great interest for future, compact accelerators due to their high accelerating gradient. Both particle-driven and laser-driven Plasma Wakefield Acceleration experiments are foreseen at the SPARC_LAB Test Facility (INFN National Laboratories of Frascati, Italy), with the aim to accelerate high-brightness electron beams. In order to optimize the efficiency of the acceleration in the plasma and preserve the quality of the accelerated beam, the knowledge of the plasma electron density is mandatory. The Stark broadening of the Hydrogen spectral lines is one of the candidates used to characterize plasma density. The implementation of this diagnostic for plasma-based experiments at SPARC_LAB is presented.

  3. Spectral anti-broadening due to four-wave mixing in optical fibers

    CERN Document Server

    Balk, Alexander M


    We show that the four-wave mixing can restrict spectral broadening. This is a general physical phenomenon that occurs in one-dimensional systems of four wave packets that resonantly interact "2-to-2": $ \\omega_1+\\omega_2=\\omega_3+\\omega_4,\\; k_1+k_2=k_3+k_4$, when an annihilation of one pair of waves results in the creation of another pair. In addition, for this phenomenon to occur, the group velocities $C_1,C_2,C_3,C_4$ of the packets should be in a certain order: The extreme value (max or min) of the four group velocities should be in the same pair with the middle value of the remaining three, e.g. $C_1

  4. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen (United States)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor


    We have investigated three binary mixtures composed of selected banana-shaped dopant in low concentrations and calamitic mesogen in high. Banana-shaped dopant forms a B7 phase, while the calamitic mesogen exhibit nematic and smectic SmA and SmC phases. The occurring mesophases have been identified by their optical textures. At dopant concentrations of 2.2 and 3.1 mol%, there is evident broadening of nematic and smectic SmA temperature ranges in respect to the pure calamitic compound. Yet, the mixture with dopant concentration of 7 mol% exhibits narrower temperature ranges of mesophases. Increasing dopant concentration caused lowering of all phase transitions temperatures (TI-N, TN-SmA, TSmA-SmC) in all investigated mixtures. Therefore, mixing classic calamitic compounds with novel banana-shaped compound in low concentrations is viable way to attain useful mesophase range for application in industry.

  5. Suppression of space broadening of exciton polariton beams by Bloch oscillation effects

    CERN Document Server

    Duan, Xudong; Zhang, Yongyou


    We theoretically study the transport of exciton polaritons under different applied photon potentials. The relation between the photon potentials and the thickness of the cavity layer is calculated by the finite element simulation. The theoretical analysis and numerical calculation indicate that the cavity photon potential is proportional to the thickness of the cavity layer with the coefficient being about $1.8$ meV/nm. Further, the periodic and linear photon potentials are considered to control the transport of the exciton polaritons in weak- and strong-field pump situations. In both situations the periodic potential cannot by itself effectively suppress the scatterings of the disorder potentials of the cavity photons and excitons and the nonlinear exciton-exciton interaction. When the linear potential is added to the cavity photons, the polariton transport exhibits the Bloch oscillation behavior. Importantly, the polariton Bloch oscillation can strongly suppress the space broadening due to the disorder pote...

  6. Annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Alves, M. J. P.; Gonzalez-Chavez, D. E.; Sommer, R. L. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, Urca, 22290-180 Rio de Janeiro, RJ (Brazil); Bohn, F. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil)


    We systematically investigate the annealing effects on the microwave linewidth broadening of FeCuNbSiB ferromagnetic films with thickness of 100 nm. We correlate the non-uniform residual stress obtained from grazing incidence x-ray diffraction measurements with the ferromagnetic resonance (FMR) linewidth due to effective field inhomogeneities measured from broadband ferromagnetic resonance absorption measurements. We also estimate the annealing temperature effect on the Gilbert and two-magnon scattering contributions to the total ferromagnetic resonance FMR linewidth. We show that the effective field inhomogeneities constitute the main contribution to the microwave linewidth, while this contribution is related to the non-uniform residual stress in the films which is reduced by thermal annealing.

  7. Amplifying modeling for broad bandwidth pulse in Nd:glass based on hybrid-broaden mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Sujingqin; Lanqin, L; Wenyi, W; Feng, J; Xiaofeng, W; Xiaomin, Z [Research Center of Laser Fusion, China Academy of Engineering Physics, P. O. Box 919-988, Mianyang, China, 621900 (China); Bin, L [School of Computer and Communication Engineering, Southwest Jiaotong University, Chengdu. China, 610031 (China)], E-mail:


    In this paper, the cross relaxation time is proposed to combine the homogeneous and inhomogeneous broaden mechanism for broad bandwidth pulse amplification model. The corresponding velocity equation, which can describe the response of inverse population on upper and low energy level of gain media to different frequency of pulse, is also put forward. The gain saturation and energy relaxation effect are also included in the velocity equation. Code named CPAP has been developed to simulate the amplifying process of broad bandwidth pulse in multi-pass laser system. The amplifying capability of multi-pass laser system is evaluated and gain narrowing and temporal shape distortion are also investigated when bandwidth of pulse and cross relaxation time of gain media are different. Results can benefit the design of high-energy PW laser system in LFRC, CAEP.

  8. Alcoholism and memory: broadening the scope of alcohol-expectancy research. (United States)

    Goldman, M S; Brown, S A; Christiansen, B A; Smith, G T


    Current biopsychosocial research on the etiology of alcoholism has begun to focus on memory processes as a possible common pathway for drinking decisions. The alcohol-expectancy construct is rooted both in cognitive psychology and alcohol research and can serve as a vehicle for this study. Reexamination of one recent review of issues in alcohol-expectancy research provides an opportunity to broaden the scope of this research with theoretical and methodological alternatives to those suggested in that review. Most importantly, this article shows that expectancy findings, discussed by Leigh (1989a) as reflecting "psychometric" limitations, are instead quite consistent with recent network models of memory structure. Such models can provide an informative guide to future research activities. It is also recommended that alcohol-expectancy research remain open to inputs from expectancy theories already developed in several psychological domains, as well as to theories of social cognition and attitude structure in addition to those advanced by Leigh.

  9. A Doppler-broadening facility for positron spin relaxation (e{sup +}SR) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gessmann, Th.; Harmat, P.; Major, J.; Seeger, A. [Max-Planck-Institut fuer Metallforschung, Institut fuer Physik, Stuttgart, Stuttgart (Germany)


    A set-up is described for the determination of the spin polarization of positrons emitted from radioactive sources that makes use of the dependence of the Doppler broadening of the 511 keV annihilation photon line on the strength and direction (with regard to the spin polarization) of an applied magnetic field. In the so-called e{sup +}SR (positron spin relaxation) technique the sample to be investigated is part of the e{sup +}-spin polarimeter. Its application to the investigation of positronium formation in condensed matter is illustrated using crystalline quartz as an example. The method earlier applied to the positron annihilation in magnetized ferromagnets is now transferred to the detection of positronium (Ps) in condensed matter. This new approach makes use of the fact, that the ratio of Ps atoms in the singlet and the triplet states is larger in a magnetic field applied parallel to the positron-spin polarization than in an antiparallel field.

  10. Shift and broadening of emission lines in Nd$^{3+}$:YAG laser crystal influenced by input energy

    Indian Academy of Sciences (India)



    Spectroscopic properties of the flashlamp-pumped Nd$^{3+}$:YAG laser as a function of input energy were studied over the range of 18–75 J. The spectral widths and shifts of quasi-three-level and four-level inter-Stark emissions within the respective intermanifold transitions of $^4$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2} $ and $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ were investigated. The emission lines of $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{9/2}$ shifted towards longer wavelength (red shift) and broadened, while the positions and linewidths of the $^{4}$F$_{3/2}$ $\\rightarrow$ $^{4}$I$_{11/2}$ transition lines remained constant by increasing the pumping energy. This is attributed to the thermal population as well as one-phonon and multiphonon emission processes in the ground state. This phenomenon degrades the output performance of the lasers.

  11. SEMICONDUCTOR DEVICES Negative bias temperature instability induced single event transient pulse narrowing and broadening (United States)

    Jianjun, Chen; Shuming, Chen; Bin, Liang; Biwei, Liu


    The effect of negative bias temperature instability (NBTI) on a single event transient (SET) has been studied in a 130 nm bulk silicon CMOS process based on 3D TCAD device simulations. The investigation shows that NBTI can result in the pulse width and amplitude of SET narrowing when the heavy ion hits the PMOS in the high-input inverter; but NBTI can result in the pulse width and amplitude of SET broadening when the heavy ion hits the NMOS in the low-input inverter. Based on this study, for the first time we propose that the impact of NBTI on a SET produced by the heavy ion hitting the NMOS has already been a significant reliability issue and should be of wide concern, and the radiation hardened design must consider the impact of NBTI on a SET.


    Energy Technology Data Exchange (ETDEWEB)

    Kilpatrick, Charles D.; Bieging, John H.; Rieke, George H. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)


    We present molecular spectroscopy toward 50 Galactic supernova remnants (SNRs) taken at millimeter wavelengths in {sup 12}CO J = 2 − 1. These observations are part of a systematic survey for broad molecular line (BML) regions indicative of interactions with molecular clouds (MCs). We detected BML regions toward 19 SNRs, including 9 newly identified BML regions associated with SNRs (G08.3–0.0, G09.9–0.8, G11.2–0.3, G12.2+0.3, G18.6–0.2, G23.6+0.3, 4C–04.71, G29.6+0.1, and G32.4+0.1). The remaining 10 SNRs with BML regions confirm previous evidence for MC interaction in most cases (G16.7+0.1, Kes 75, 3C 391, Kes 79, 3C 396, 3C 397, W49B, Cas A, and IC 443), although we confirm that the BML region toward HB 3 is associated with the W3(OH) H ii region, not the SNR. Based on the systemic velocity of each MC, molecular line diagnostics, and cloud morphology, we test whether these detections represent SNR–MC interactions. One of the targets (G54.1+0.3) had previous indications of a BML region, but we did not detect broadened emission toward it. Although broadened {sup 12}CO J = 2 − 1 line emission should be detectable toward virtually all SNR–MC interactions, we find relatively few examples; therefore, the number of interactions is low. This result favors mechanisms other than supernova feedback as the basic trigger for star formation. In addition, we find no significant association between TeV gamma-ray sources and MC interactions, contrary to predictions that SNR–MC interfaces are the primary venues for cosmic ray acceleration.

  13. Citizen Science: Broadening Access and Engagement Through Community Partnerships, Aerospace Education and Water Quality Research (United States)

    Johnson, M. A.


    We applied a new approach to the design and development of citizen science learning opportunities to enhance outreach to diverse student populations, while advancing water quality research and aerospace education. This collaborative approach to informal science, technology, engineering, and math (STEM) and aerospace education required innovative partnerships between private general aviation pilots, researchers, teachers, and students. This research explored the development of active partnerships required to facilitate community engaged science, with an emphasis on increased participation of women and girls and people of color, while creating new exploratory pathways for broadening access to and engagement in STEM learning experiences. We developed an outreach program through collaborative planning with local schools to create new STEM learning experiences based upon basic aerospace education concepts and an existing water quality research project designed to track harmful algal blooms (HAB) that can produce toxins called cyanobacteria, also known as blue-green algae, which can impact drinking, fishing, and recreational waters. General aviation pilots functioning as citizen scientists obtained high-resolution aerial images while flying over potentially impacted waters. Aerial data was made available to teachers and students, as well as researchers participating in the existing water quality program lead by NASA Glenn Research Center. Teachers used the images and results to educate in climate change and the dangers of HAB. Students were able to compare aerial data with their own observations, and also gained experience in aeronautical science through field trips to local airports, hands-on experience with private research aircraft, specialized equipment used for data collection, and advanced ground instruction from research pilots. As a result of reaching out to local educators serving diverse student populations and facilitating collaborative planning, we

  14. Hippocampal long-term potentiation is not accompanied by presynaptic spike broadening, unlike synaptic potentiation by K+ channel blockers. (United States)

    Laerum, H; Storm, J F


    The expression of hippocampal long-term potentiation (LTP) is thought to be at least partly due to increased transmitter release. To test whether this increase is due to a broadening of the presynaptic action potential, we have compared the presynaptic fibre volley before and after LTP induction, or application of K+ channel blockers, in CA1 of rat hippocampal slices. Tetraethylammonium (TEA; 1 mM) induced a parallel increase in the fibre volley duration of the slope of the field EPSP, indicating that a presynaptic spike broadening underlying synaptic potentiation can be detected. In contrast, induction of LTP did not produce any measurable change in the fibre volley, although the average increase in the EPSP slope was larger than with TEA. These results indicate that LTP expression is not primarily due to a presynaptic spike broadening.

  15. H2-,He-and CO2-line broadening coefficients and pressure shifts for the HITRAN database (United States)

    Wilzewski, Jonas; Gordon, Iouli E.; Rothman, Laurence S.


    To increase the potential of the HITRAN database in astronomy, experimental and theoretical line broadening coefficients and line shifts of molecules of planetary interest broadened by H2,He,and CO2 have been assembled from available peer-reviewed sources. Since H2 and He are major constituents in the atmospheres of gas giants, and CO2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for studying planetary atmospheres. The collected data were used to create semi-empirical models for complete data sets from the microwave to the UV part of the spectrum of the studied molecules. The presented work will help identify the need for further investigations of broadening and shifting of spectral lines.

  16. [Participatory potential and deliberative function: a debate on broadening the scope of democracy through the health councils]. (United States)

    Bispo Júnior, José Patrício; Gerschman, Sílvia


    This article reflects upon the relation between democracy and health councils. It seeks to analyze the councils as a space for broadening the scope of democracy. First, some characteristics and principles of the liberal democratic regime are presented, with an emphasis on the minimalist and procedural approach of decision-making. The fragilities of the representative model and the establishment of new relations between the Government and society are then discussed in light of the new social grammar and the complexity of the division between governmental and societal responsibilities. The principles of deliberative democracy and the idea of substantive democracy are subsequently presented. Broadening the scope of democracy is understood not only as the guarantee of civil and political rights, but also especially, of social rights. Lastly, based on discussion of the participation and deliberation categories, the health councils are analyzed as potential mechanisms for broadening the scope of democracy.

  17. Complete compensation of pulse broadening in an amplifier-based slow light system using a nonlinear regeneration element. (United States)

    Chin, Sanghooon; Gonzalez-Herraez, Miguel; Thévenaz, Luc


    We experimentally demonstrate complete compensation of pulse broadening in an amplifier-based slow light system. The configuration of the delay line basically consists of two stages: a conventional Brillouin slow light system and a nonlinear regeneration element. Signal pulses experienced both time delay and temporal broadening through the Brillouin delay line and then the delayed pulses were delivered into a nonlinear optical loop mirror. Due to the nonlinear response of the transmission of the fiber loop, the inevitably broadened pulses were moderately compressed in the output of the loop, without loss in the capacity to delay the pulses. The overall result is that, for the maximum delay, the width of the pulse could be kept below the input width while the time delays introduced by the slow light element were preserved. Using this delay line, a signal pulse with duration of 27 ns at full width at half maximum was delayed up to 1.3-bits without suffering from signal distortion.

  18. A line-broadening analysis model for the microstructural characterization of nanocrystalline materials from asymmetric x-ray diffraction peaks. (United States)

    Pantoja-Cortés, Juan; Sánchez-Bajo, Florentino; Ortiz, Angel L


    Nanograin sizes and crystal lattice microstrains in nanocrystalline materials are typically evaluated from the broadening of their x-ray diffraction (XRD) peaks under the assumption of symmetrical diffraction profiles. Since this assumption is not entirely satisfactory, we formulate a line-broadening analysis model of a single peak that considers explicitly the XRD peak asymmetry. The model is a generalization of the variance method in which the shape of the XRD peaks is idealized through asymmetrical split pseudo-Voigt functions. The model is validated on two nanocrystalline powders.

  19. Water-vapor line broadening and shifting by air, nitrogen, oxygen, and argon in the 720-nm wavelength region (United States)

    Grossmann, Benoist E.; Browell, Edward V.


    High-resolution spectroscopic measurements of H2O vapor in the 720-nm wavelength region were conducted to investigate the broadening and shifting of H2O lines by air, nitrogen, oxygen, and argon over a wide range of pressures and temperatures. For each of the buffer gases under study, a linear relationship was found between the widths and the shifts, with the broader lines having the smaller pressure shifts. The pressure shifts measured compared favorably with theoretical values reported by Bykov et al. (1988). The temperature-dependence exponents for air-broadening were found to be J-dependent, with the lower-J lines having the higher exponents.

  20. Point defects in MnSi and YBCO studied by Doppler Broadening Spectroscopy using a positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Reiner, Markus


    The positron beam NEPOMUC was used in order to investigate MnSi and YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) single crystals. The Doppler broadening of the annihilation radiation of electron-positron pairs was analyzed. Thus, the concentration of Mn vacancies in MnSi crystals was determined. In thin YBCO films, the Doppler broadening is correlated with the oxygen deficiency δ. Its spatial distribution and its high-temperature behavior were studied using positrons.

  1. High precision measurement of ultraweak transitions of the a${^1}{\\triangle}_g{\\leftarrow}$X $^3{\\Sigma}^{-}_g$ $(0,0)$ band of molecular oxygen

    CERN Document Server

    Das, Dipankar


    We have used a highly sensitive cavity-enhanced frequency modulation spectroscopy technique to measure different parameters of the ultraweak transitions of a${^1}{\\triangle}_g{\\leftarrow}$X $^3{\\Sigma}^{-}_g$ $(0,0)$ band of molecular oxygen in the range 7640 cm$^{-1}$ to 7917 cm$^{-1}$. The self-broadened half-width and air-broadened half-width of the transitions have been measured for three different pressures for both $^{16}$O$_2$ and $^{18}$O$_2$. To measure the line intensity and self-broadened half-width we have used ultra pure oxygen sample and air-broadened half-width was measured with dry air sample. The $(0,0)$ band of $^{16}$O$_2$ and $^{18}$O$_2$ show weak quadrupole transitions with line intensities ranging from $1\\times10^{-30}$ to $1.9\\times10^{-28}$ cm/molecule. The measurements are in excellent agreement with the recent measurement of Rothman et. al

  2. Single-Band and Dual-Band Infrared Detectors (United States)

    Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor); Soibel, Alexander (Inventor); Nguyen, Jean (Inventor); Khoshakhlagh, Arezou (Inventor)


    Bias-switchable dual-band infrared detectors and methods of manufacturing such detectors are provided. The infrared detectors are based on a back-to-back heterojunction diode design, where the detector structure consists of, sequentially, a top contact layer, a unipolar hole barrier layer, an absorber layer, a unipolar electron barrier, a second absorber, a second unipolar hole barrier, and a bottom contact layer. In addition, by substantially reducing the width of one of the absorber layers, a single-band infrared detector can also be formed.

  3. Adhesives for fixed orthodontic bands. (United States)

    Millett, Declan T; Glenny, Anne-Marie; Mattick, Rye Cr; Hickman, Joy; Mandall, Nicky A


    Orthodontic treatment involves using fixed or removable appliances (dental braces) to correct the positions of teeth. It has been shown that the quality of treatment result obtained with fixed appliances is much better than with removable appliances. Fixed appliances are, therefore, favoured by most orthodontists for treatment. The success of a fixed orthodontic appliance depends on the metal attachments (brackets and bands) being attached securely to the teeth so that they do not become loose during treatment. Brackets are usually attached to the front and side teeth, whereas bands (metal rings that go round the teeth) are more commonly used on the back teeth (molars). A number of adhesives are available to attach bands to teeth and it is important to understand which group of adhesives bond most reliably, as well as reducing or preventing dental decay during the treatment period. To evaluate the effectiveness of the adhesives used to attach bands to teeth during fixed appliance treatment, in terms of:(1) how often the bands come off during treatment; and(2) whether they protect the banded teeth against decay during fixed appliance treatment. The following electronic databases were searched: Cochrane Oral Health's Trials Register (searched 2 June 2016), Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 5) in the Cochrane Library (searched 2 June 2016), MEDLINE Ovid (1946 to 2 June 2016) and EMBASE Ovid (1980 to 2 June 2016). We searched and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. Randomised and controlled clinical trials (RCTs and CCTs) (including split-mouth studies) of adhesives used to attach orthodontic bands to molar teeth were selected. Patients with full arch fixed orthodontic appliance(s) who had bands attached to molars were included. All review authors


    Energy Technology Data Exchange (ETDEWEB)

    Kraus, M. [Astronomický ústav, Akademie věd České republiky, Fričova 298, 251 65 Ondřejov (Czech Republic); Oksala, M. E. [LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris Diderot, 5 place Jules Janssen, F-92190, Meudon (France); Cidale, L. S.; Arias, M. L.; Torres, A. F. [Departamento de Espectroscopía Estelar, Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata (Argentina); Fernandes, M. Borges, E-mail: [Observatório Nacional, Rua General José Cristino 77, 20921-400 São Cristovão, Rio de Janeiro (Brazil)


    B[e] supergiants (B[e]SGs) are evolved massive stars in a short-lived transition phase. During this phase, these objects eject large amounts of material, which accumulate in a circumstellar disk-like structure. The expelled material is typically dense and cool, providing the cradle for molecule and dust condensation and for a rich, ongoing chemistry. Very little is known about the chemical composition of these disks, beyond the emission from dust and CO revolving around the star on Keplerian orbits. As massive stars preserve an oxygen-rich surface composition throughout their life, other oxygen-based molecules can be expected to form. As SiO is the second most stable oxygen compound, we initiated an observing campaign to search for first-overtone SiO emission bands. We obtained high-resolution near-infrared L-band spectra for a sample of Galactic B[e]SGs with reported CO band emission. We clearly detect emission from the SiO first-overtone bands in CPD-52 9243 and indications for faint emission in HD 62623, HD 327083, and CPD-57 2874. From model fits, we find that in all these stars the SiO bands are rotationally broadened with a velocity lower than observed in the CO band forming regions, suggesting that SiO forms at larger distances from the star. Hence, searching for and analyzing these bands is crucial for studying the structure and kinematics of circumstellar disks, because they trace complementary regions to the CO band formation zone. Moreover, since SiO molecules are the building blocks for silicate dust, their study might provide insight in the early stage of dust formation.

  5. A far wing line shape theory and its application to the water vibrational bands (II) (United States)

    Ma, Q.; Tipping, R. H.


    Attention is given to a far wing line shape theory based on binary collision and quasi-static approximations. The theory is applicable for both the LF and HF wings of vibrational-rotational bands. It is used to calculate the frequency and temperature dependence of the continuous absorption coefficient for frequencies up to 10,000/cm for pure water vapor. The results are compared with existing laboratory data in the 2400-2700/cm window and in the 3000-4300/cm band center region, with field measurements in the 2000-2225/cm region and with a recent experimental measurement near 9466/cm. It is concluded that both the magnitude and temperature dependence of the water vapor continuum can be accounted for by the present theory without the introduction of any adjustable parameters. Refinements of the theory and extension to foreign-broadened absorption are also discussed.

  6. Band gap bowing in NixMg1-xO (United States)

    Niedermeier, Christian A.; Råsander, Mikael; Rhode, Sneha; Kachkanov, Vyacheslav; Zou, Bin; Alford, Neil; Moram, Michelle A.


    Epitaxial transparent oxide NixMg1-xO (0 ≤ x ≤ 1) thin films were grown on MgO(100) substrates by pulsed laser deposition. High-resolution synchrotron X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the thin films are compositionally and structurally homogeneous, forming a completely miscible solid solution. Nevertheless, the composition dependence of the NixMg1-xO optical band gap shows a strong non-parabolic bowing with a discontinuity at dilute NiO concentrations of x band structure and the density of states demonstrate that deep Ni 3d levels are introduced into the MgO band gap, which significantly reduce the fundamental gap as confirmed by optical absorption spectra. These states broaden into a Ni 3d-derived conduction band for x > 0.074 and account for the anomalously large band gap narrowing in the NixMg1-xO solid solution system.


    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y.; Liu, A.-W.; Li, X.-F.; Wang, J.; Cheng, C.-F.; Sun, Y. R.; Lambo, R.; Hu, S.-M., E-mail: [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026 (China)


    The 782 nm band of CO{sub 2}, in a transparent window of Earth's atmosphere, was the first CO{sub 2} band observed 80 yr ago in the spectra of Venus. The band is very weak and therefore not saturated by the thick atmosphere of Venus, but its spectral parameters are still very limited due to the difficulty of detecting it in the laboratory. It is the highest overtone (ν{sub 1} + 5ν{sub 3}) of CO{sub 2} given in widely used spectroscopy databases such as HITRAN and GEISA. In the present work, the band is studied using a cavity ring-down spectrometer with ultra-high sensitivity as well as high precision. The positions of 55 lines in the band were determined with an absolute accuracy of 3 × 10{sup –5} cm{sup –1}, two orders of magnitude better than previous studies. The line intensities, self-induced pressure broadening coefficients, and the shift coefficients were also derived from the recorded spectra. The obtained spectral parameters can be applied to model the spectra of the CO{sub 2}-rich atmospheres of planets like Venus and Mars.

  8. Correlations in a Band Insulator (United States)

    Sentef, Michael; Kunes, Jan; Kampf, Arno P.; Werner, Philipp


    Using DMFT we find a discontinuous band-to-Mott insulator transition upon an increase in the local Coulomb repulsion in a covalent band insulator [1,2], defined as a band insulator with partially filled local orbitals. The corresponding band gap is a hybridization gap arising from a particular pattern of hopping integrals. Similar characteristics apply to materials such as FeSi, FeSb2 or CoTiSb [3], some of which exhibit temperature dependent magnetic and transport properties reminiscent of Kondo insulators. Both charge and spin gaps in the covalent band insulator shrink with increasing Coulomb repulsion. At moderate interaction strengths the gap renormalization is well described by a renormalization factor analogous to the quasiparticle weight in a Fermi liquid. [4pt] [1] M. Sentef, J. Kunes, P. Werner, and A.P. Kampf, Phys. Rev. B 80, 155116 (2009) [0pt] [2] A.P. Kampf, M. Kollar, J. Kunes, M. Sentef, and D. Vollhardt, arXiv:0910.5126

  9. William Band at Yenching University (United States)

    Hu, Danian


    William Band (1906-1993) has been widely remembered by his American colleagues and students as ``a fine physicist and teacher,'' who taught at Washington State University in Pullman between 1949 and 1971 and authored Introduction to Quantum Statistics (1954) and Introduction to Mathematical Physics (1959). Not many, however, knew much about Band's early career, which was very ``uncommon and eventful.'' Born in England, Band graduated from University of Liverpool in 1927 with an MsSc degree in physics. Instead of pursuing his Ph.D. at Cambridge, he chose to teach physics at Yenching University, a prestigious Christian university in Beijing, China. Arriving in 1929, Band established his career at Yenching, where he taught and researched the theory of relativity and quantum mechanics, pioneered the study on low-temperature superconductivity in China, founded the country's first graduate program in physics, and chaired the Physics Department for 10 years until he fled from Yenching upon hearing of the attack on Pearl Harbor. It took him two years to cross Japanese occupied areas under the escort of the Communist force; he left China in early 1945. This presentation will explore Band's motivation to work in China and his contributions to the Chinese physics research and education.

  10. Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic turbulence and tangled molecular clouds (United States)

    Hacar, A.; Alves, J.; Burkert, A.; Goldsmith, P.


    Context. Since their first detection in the interestellar medium, (sub-)millimeter line observations of different CO isotopic variants have routinely been employed to characterize the kinematic properties of the gas in molecular clouds. Many of these lines exhibit broad linewidths that greatly exceed the thermal broadening expected for the low temperatures found within these objects. These observed suprathermal CO linewidths are assumed to originate from unresolved supersonic motions inside clouds. Aims: The lowest rotational J transitions of some of the most abundant CO isotopologues, 12CO and 13CO, are found to present large optical depths. In addition to well-known line saturation effects, these large opacities present a non-negligible contribution to their observed linewidths. Typically overlooked in the literature, in this paper we aim to quantify the impact of these opacity broadening effects on the current interpretation of the CO suprathermal line profiles. Methods: Combining large-scale observations and LTE modeling of the ground J = 1-0 transitions of the main 12CO, 13CO, C18O isotopologues, we have investigated the correlation of the observed linewidths as a function of the line opacity in different regions of the Taurus molecular cloud. Results: Without any additional contributions to the gas velocity field, a large fraction of the apparently supersonic (ℳ ~ 2-3) linewidths measured in both 12CO and 13CO (J = 1-0) lines can be explained by the saturation of their corresponding sonic-like, optically thin C18O counterparts assuming standard isotopic fractionation. Combined with the presence of multiple components detected in some of our C18O spectra, these opacity effects also seem to be responsible for most of the highly supersonic linewidths (ℳ > 8-10) detected in some of the broadest 12CO and 13CO spectra in Taurus. Conclusions: Our results demonstrate that most of the suprathermal 12CO and 13CO linewidths reported in nearby clouds like Taurus

  11. Broadening and Amplification of an Infrared Femtosecond Pulse for Optical Parametric Chirped-Pulse Amplification

    Institute of Scientific and Technical Information of China (English)

    WANG He-Lin; YANG Ai-Jun; LENG Yu-Xin


    A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA).The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically.By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity,the pre-stretching pulse from an (O)ffner stretcher is further broadened to above 200ps,which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system.The bandwidth of the amplified pulse is 1.5 nm,and an output energy of 2mJ is achieved at a repetition rate of 10 Hz.Optical parametric chirped pulse amplification (OPCPA)[1-4] has attracted a great deal of attention as the most promising technique for generating ultrashort ultrahigh-peak-power laser pulses because of its very broad gain bandwidth,negligible thermal load on the nonlinear crystal,and extremely high singlepass gain as compared to amplifiers based on laser gain media.For efficient amplification and high fidelity of dispersion compensation in OPCPA,a femtosecond seed pulse is first stretched to several tens of picoseconds with a bulk grating stretcher or a fiber stretcher.%A high-average-power diode-pumped narrowband regenerative chirped pulse amplifier is developed using the thin-rod Nd:YAG laser architecture for optical parametric chirped-pulse amplification (OPCPA). The effect of the etalons on the amplified pulse in the regenerative cavity is studied experimentally and theoretically. By inserting glass etalons of thickness 1 mm and 5 mm into the regenerative cavity, the pre-stretching pulse from an (O)finer stretcher is further broadened to above 200 ps, which matches the amplification windows of the signal pulses in OPCPA and is suitable for use as a pump source in the OPCPA system. The bandwidth of the amplified pulse is 1.5 nm, and an

  12. Is it only the regulatory status? Broadening the debate on cisgenic plants. (United States)

    van Hove, Lilian; Gillund, Frøydis


    In current debates on emerging technologies for plant breeding in Europe, much attention has been given to the regulatory status of these techniques and their public acceptance. At present, both genetically modified plants with cisgenic approaches-using genes from crossable species-as well as transgenic approaches-using genes from different species-fall under GMO regulation in the EU and both are mandatorily labelled as GMOs. Researchers involved in the early development of cisgenic GM plants convey the message that the potential use and acceptance of cisgenic approaches will be seriously hindered if GMO regulations are not adjusted. Although the similar treatment and labelling of transgenic and cisgenic plants may be a legitimate concern for the marketability of a cisgenic GM plant, there are concerns around their commercialization that reach beyond the current focus on (de)regulation. In this paper, we will use the development of the cisgenic GM potato that aims to overcome 'late blight'-the most devastating potato disease worldwide-as a case to argue that it is important to recognize, reflect and respond to broader concerns than the dominant focus on the regulatory 'burden' and consumer acceptance. Based on insights we gained from discussing this case with diverse stakeholders within the agricultural sector and potato production in Norway during a series of workshops, we elaborate on additional issues such as the (technical) solution offered; different understandings of the late blight problem; the durability of the potato plant resistance; and patenting and ownership. Hence, this paper contributes to empirical knowledge on stakeholder perspectives on emerging plant breeding technologies, underscoring the importance to broaden the scope of the debate on the opportunities and challenges of agricultural biotechnologies, such as cisgenic GM plants. The paper offers policy-relevant input to ongoing efforts to broaden the scope of risk assessments of agricultural

  13. Strategies for broadening participation in the Maryland Sea Grant REU program (United States)

    Moser, F. C.; Kramer, J.; Allen, J. R.


    A core goal of the ocean science community is to increase gender and ethnic diversity in its scientific workforce. Maryland Sea Grant strives to provide women and students from underrepresented groups in marine science opportunities to participate in its NSF-supported Research Experiences for Undergraduates (REU) program in estuarine processes. While women currently dominate the applicant student pool, and often the accepted student pool, we are trying a variety of strategies to increase the number of applicants and accepted students from underrepresented groups who might not otherwise be lured into marine science research and, ultimately, careers. For example, we have built partnerships with multicultural-focused undergraduate research programs and institutions, which can raise awareness about our REU program and its commitment to broadening diversity. Further, we work to attract first generation college students, students from small colleges with limited marine science opportunities and students from varied racial and ethnic backgrounds using such strategies as: 1) developing trust and partnerships with faculty at minority serving institutions; 2) expanding our outreach in advertising our program; 3) recruiting potential applicants at professional meetings; 4) targeting minority serving institutions within and beyond our region; 5) encouraging our REU alumni to promote our REU program among their peers; and 6) improving our application process. We believe these efforts contribute to the increase in the diversity of our summer-supported students and the change in the composition of our applicant pool over the last decade. Although we cannot definitively identify which strategies are the most effective at broadening participation in our program, we attribute most of our improvements to some combination of these strategies. In addition, pre- and post-surveying of our REU students improves our understanding of effective tools for recruiting and adapting our program

  14. Local Talent: By Tapping into the Resources Just outside Their School Walls, Music Teachers Can Help Broaden Their Students' Horizons (United States)

    Randall, Mac


    Many music teachers across the country have learned how beneficial it can be to tap into the communities around them. The author discusses how music teachers can help broaden their students' horizons by tapping into the resources just outside their school walls. One way is by employing local talents. Another is to put an ad in nearby music stores,…

  15. Neural broadening or neural attenuation? Investigating age-related dedifferentiation in the face network in a large lifespan sample. (United States)

    Park, Joonkoo; Carp, Joshua; Kennedy, Kristen M; Rodrigue, Karen M; Bischof, Gerard N; Huang, Chih-Mao; Rieck, Jennifer R; Polk, Thad A; Park, Denise C


    Previous studies have found that cortical responses to different stimuli become less distinctive as people get older. This age-related dedifferentiation may reflect the broadening of the tuning curves of category-selective neurons (broadening hypothesis) or it may be due to decreased activation of category-selective neurons (attenuation hypothesis). In this study, we evaluated these hypotheses in the context of the face-selective neural network. Over 300 participants, ranging in age from 20 to 89 years, viewed images of faces, houses, and control stimuli in a functional magnetic resonance imaging session. Regions within the core face network and extended face network were identified in individual subjects. Activation in many of these regions became significantly less face-selective with age, confirming previous reports of age-related dedifferentiation. Consistent with the broadening hypothesis, this dedifferentiation in the fusiform face area (FFA) was driven by increased activation to houses. In contrast, dedifferentiation in the extended face network was driven by decreased activation to faces, consistent with the attenuation hypothesis. These results suggest that age-related dedifferentiation reflects distinct processes in different brain areas. More specifically, dedifferentiation in FFA activity may be due to broadening of the tuning curves for face-selective neurons, while dedifferentiation in the extended face network reflects reduced face- or emotion-selective activity.

  16. Resonance broadening due to particle scattering and mode-coupling in the quasi-linear relaxation of electron beams

    CERN Document Server

    Bian, Nicolas H; Ratcliffe, Heather


    Of particular interest for radio and hard X-ray diagnostics of accelerated electrons during solar flares is the understanding of the basic non-linear mechanisms regulating the relaxation of electron beams propagating in turbulent plasmas. In this work, it is shown that in addition to scattering of beam electrons, scattering of the beam-generated Langmuir waves via for instance mode-coupling, can also result in broadening of the wave-particle resonance. We obtain a resonance-broadened version of weak-turbulence theory with mode-coupling to ion-sound modes. Resonance broadening is presented here as a unified framework which can quantitatively account for the reduction and possible suppression of the beam instability due to background scattering of the beam electrons themselves or due to scattering of the beam-generated Langmuir waves in fluctuating plasmas. Resonance broadening being essentially equivalent to smoothing of the electron phase-space distribution, it is used to construct an intuitive physical pictu...

  17. Electron Density and Temperature Measurement by Stark Broadening in a Cold Argon Arc-Plasma Jet at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    ZHOU Qiuping; CHENG Cheng; MENG Yuedong


    Determination of both the electron density and temperature simultaneously in a cold argon arc-plasma jet by analyzing the Stark broadening of two different emission lines is presented.This method is based on the fact that the Stark broadening of different lines has a different dependence on the electron density and temperature.Therefore,a comparison of two or more line broadenings allows us to diagnose the electron density and temperature simultaneously.In this study we used the first two Balmer series hydrogen lines H_α and H_β for their large broadening width.For this purpose,a small amount of hydrogen was introduced into the discharge gas.The results of the Gigosos-Cardenoso computational model,considering more relevant processes for the hydrogen Balmer lines,is used to process the experimental data.With this method,we obtained reliable electron density and temperature,1.88 ×10 ~(15) cm~(-3 )and 13000 K,respectively.Possible sources of error were also analyzed.

  18. Mortality Salience and Positive Affect Influence Adolescents' Attitudes toward Peers with Physical Disabilities: Terror Management and Broaden and Build Theories (United States)

    Taubman-Ben-Ari, Orit; Eherenfreund-Hager, Ahinoam; Findler, Liora


    Attitudes toward teenagers with and without physical disabilities, and their social acceptance, were examined from the perspective of terror management theory and the broaden and build theory. Participants (n = 390, aged 13-17) were divided into 3 experimental conditions: positive emotions, mortality salience, and control. Then, they were shown…

  19. Peak broadening in paper chromatography and related techniques : IV. The mechanism of the mass transfer term in paper chromatography

    NARCIS (Netherlands)

    Ligny, C.L. de; Remijnse, A.G.


    The mechanism of peak broadening in paper chromatography is investigated by comparing the peak widths obtained in chromatography with those caused only by diffusion, for a set of amino acids of widely differing RF values and with eight kinds of Whatman paper. The results show that longitudinal diff

  20. Linewidth broadening and emission saturation of a resonantly excited quantum dot monitored via an off-resonant cavity mode

    DEFF Research Database (Denmark)

    Ulhaq, A.; Ates, Serkan; Weiler, S.;


    We report on the robustness of a detuned mode channel for reading out the relevant s-shell properties of a resonantly excited coupled quantum dot (QD) in a pillar microcavity. The line broadening of the QD s-shell is “monitored” by the mode signal with high conformity to the directly measured QD ...


    Energy Technology Data Exchange (ETDEWEB)

    Kawate, T. [Kwasan and Hida Observatory, Kyoto University, Kurabashira, Kamitakaracho, Takayama, Gifu 506-1314 (Japan); Imada, S. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)


    We have studied the relationship between the location of EUV non-thermal broadening and high-energy particles during large flares using the EUV Imaging Spectrometer on board Hinode, the Nobeyama Radio Polarimeter, the Nobeyama Radioheliograph, and the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. We have analyzed five large flare events that contain thermal-rich, intermediate, and thermal-poor flares classified by the definition discussed in the paper. We found that, in the case of thermal-rich flares, the non-thermal broadening of Fe XXIV occurred at the top of the flaring loop at the beginning of the flares. The source of 17 GHz microwaves is located at the footpoint of the flare loop. On the other hand, in the case of intermediate/thermal-poor flares, the non-thermal broadening of Fe XXIV occurred at the footpoint of the flare loop at the beginning of the flares. The source of 17 GHz microwaves is located at the top of the flaring loop. We discussed the difference between thermal-rich and intermediate/thermal-poor flares based on the spatial information of non-thermal broadening, which may provide clues that the presence of turbulence plays an important role in the pitch angle scattering of high-energy electrons.

  2. Mortality Salience and Positive Affect Influence Adolescents' Attitudes toward Peers with Physical Disabilities: Terror Management and Broaden and Build Theories (United States)

    Taubman-Ben-Ari, Orit; Eherenfreund-Hager, Ahinoam; Findler, Liora


    Attitudes toward teenagers with and without physical disabilities, and their social acceptance, were examined from the perspective of terror management theory and the broaden and build theory. Participants (n = 390, aged 13-17) were divided into 3 experimental conditions: positive emotions, mortality salience, and control. Then, they were shown…

  3. An Age-Related Mechanism of Emotion Regulation: Regulating Sadness Promotes Children's Learning by Broadening Information Processing (United States)

    Davis, Elizabeth L.


    Emotion regulation predicts positive academic outcomes like learning, but little is known about "why". Effective emotion regulation likely promotes learning by broadening the scope of what may be attended to after an emotional event. One hundred twenty-six 6- to 13-year-olds' (54% boys) regulation of sadness was examined for changes in…

  4. Linear methods in band theory

    DEFF Research Database (Denmark)

    Andersen, O. Krogh


    and they specify the boundary conditions on a single MT or atomic sphere in the most convenient way. This method is very well suited for self-consistent calculations. The empty-lattice test is applied to the linear-MTO method and the free-electron energy bands are accurately reproduced. Finally, it is shown how......Two approximate methods for solving the band-structure problem in an efficient and physically transparent way are presented and discussed in detail. The variational principle for the one-electron Hamiltonian is used in both schemes, and the trial functions are linear combinations of energy......-independent augmented plane waves (APW) and muffin-tin orbitals (MTO), respectively. The secular equations are therefore eigenvalue equations, linear in energy. The trial functions are defined with respect to a muffin-tin (MT) potential and the energy bands depend on the potential in the spheres through potential...

  5. X-Band PLL Synthesizer

    Directory of Open Access Journals (Sweden)

    P. Kutin


    Full Text Available This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal from the frequency doubler is filtered by a band-pass filter and finally amplified by a single stage amplifier.

  6. The IACOB project . III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars (United States)

    Simón-Díaz, S.; Godart, M.; Castro, N.; Herrero, A.; Aerts, C.; Puls, J.; Telting, J.; Grassitelli, L.


    Context. The term macroturbulent broadening is commonly used to refer to a certain type of non-rotational broadening affecting the spectral line profiles of O- and B-type stars. It has been proposed to be a spectroscopic signature of the presence of stellar oscillations; however, we still lack a definitive confirmation of this hypothesis. Aims: We aim to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars to evaluate its physical origin. Methods: We used high-resolution spectra of 430 stars with spectral types in the range O4 - B9 (all luminosity classes) compiled in the framework of the IACOB project. We characterized the line broadening of adequate diagnostic metal lines using a combined Fourier transform and goodness-of-fit technique. We performed a quantitative spectroscopic analysis of the whole sample using automatic tools coupled with a huge grid of fastwind models to determine their effective temperatures and gravities. We also incorporated quantitative information about line asymmetries into our observational description of the characteristics of the line profiles, and performed a comparison of the shape and type of line-profile variability found in a small sample of O stars and B supergiants with still undefined pulsational properties and B main-sequence stars with variable line profiles owing to a well-identified type of stellar oscillations or to the presence of spots in the stellar surface. Results: We present a homogeneous and statistically significant overview of the (single snapshot) line-broadening properties of stars in the whole O and B star domain. We find empirical evidence of the existence of various types of non-rotational broadening agents acting in the realm of massive stars. Even though all these additional sources of line-broadening could be quoted and quantified as a macroturbulent broadening from a practical point of view, their physical origin can be different. Contrarily to the early- to

  7. Holographic Multi-Band Superconductor

    CERN Document Server

    Huang, Ching-Yu; Maity, Debaprasad


    We propose a gravity dual for the holographic superconductor with multi-band carriers. Moreover, the currents of these carriers are unified under a global non-Abelian symmetry, which is dual to the bulk non-Abelian gauge symmetry. We study the phase diagram of our model, and find it qualitatively agrees with the one for the realistic 2-band superconductor, such as MgB2. We also evaluate the holographic conductivities and find the expected mean-field like behaviors in some cases. However, for a wide range of the parameter space, we also find the non-mean-field like behavior with negative conductivities.

  8. Analysis of superdeformed rotational bands (United States)

    Lalazissis, G. A.; Hara, K.


    Available experimental data for the ΔI=2 transition energies in superdeformed bands are analyzed by using an extended one-point formula. The existence of deviations from the smooth behavior is confirmed in many bands. However, we stress that one cannot necessarily speak about regular staggering patterns as they are mostly irregular. We present a simulation of the experimental data in terms of a simple model, which suggests that the irregularities may stem from the presence of irregular kinks in the rotational spectrum. However, at present, where such kinks may come from is an open question.

  9. X-Band PLL Synthesizer


    P. Kutin; Vagner, P.


    This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal ...

  10. Modeling Solvent Broadening on the Vibronic Spectra of a Series of Coumarin Dyes. From Implicit to Explicit Solvent Models. (United States)

    Cerezo, Javier; Avila Ferrer, Francisco J; Prampolini, Giacomo; Santoro, Fabrizio


    We present a protocol to estimate the solvent-induced broadening of electronic spectra based on a model that explicitly takes into account the environment embedding the solute. Starting from a classical approximation of the solvent contribution to the spectrum, the broadening arises from the spread of the excitation energies due to the fluctuation of the solvent coordinates, and it is represented as a Gaussian line shape that convolutes the vibronic spectrum of the solute. The latter is computed in harmonic approximation at room temperature with a time-dependent approach. The proposed protocol for the computation of spectral broadening exploits molecular dynamics (MD) simulations performed on the solute-solvent system, keeping the solute degrees of freedom frozen, followed by the computation of the excitation properties with a quantum mechanics/molecular mechanics (QM/MM) approach. The factors that might influence each step of the protocol are analyzed in detail, including the selection of the empirical force field (FF) adopted in the MD simulations and the QM/MM partition of the system to compute the excitation energies. The procedure is applied to a family of coumarin dyes, and the results are compared with experiments and with the predictions of a very recent work (Cerezo et al., Phys. Chem. Chem. Phys. 2015, 17, 11401-11411), where an implicit model was adopted for the solvent. The final spectra of the considered coumarins were obtained without including ad hoc phenomenological parameters and indicate that the broadenings computed with explicit and implicit models both follow the experimental trend, increasing as the polarity change from the initial to the final state increases. More in detail, the implicit model provides larger estimations of the broadening that are closer to the experimental evidence, while explicit models appear to better capture relative differences arising from different solvents or different solutes. Possible inaccuracies of the adopted

  11. Investigation of the collision line broadening problem as applicable to the NASA Optical Plume Anomaly Detection (OPAD) system, phase 1 (United States)

    Dean, Timothy C.; Ventrice, Carl A.


    As a final report for phase 1 of the project, the researchers are submitting to the Tennessee Tech Office of Research the following two papers (reprinted in this report): 'Collision Line Broadening Effects on Spectrometric Data from the Optical Plume Anomaly System (OPAD),' presented at the 30th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 27-29 June 1994, and 'Calculation of Collision Cross Sections for Atomic Line Broadening in the Plume of the Space Shuttle Main Engine (SSME),' presented at the IEEE Southeastcon '95, 26-29 March 1995. These papers fully state the problem and the progress made up to the end of NASA Fiscal Year 1994. The NASA OPAD system was devised to predict concentrations of anomalous species in the plume of the Space Shuttle Main Engine (SSME) through analysis of spectrometric data. The self absorption of the radiation of these plume anomalies is highly dependent on the line shape of the atomic transition of interest. The Collision Line Broadening paper discusses the methods used to predict line shapes of atomic transitions in the environment of a rocket plume. The Voigt profile is used as the line shape factor since both Doppler and collisional line broadening are significant. Methods used to determine the collisional cross sections are discussed and the results are given and compared with experimental data. These collisional cross sections are then incorporated into the current self absorbing radiative model and the predicted spectrum is compared to actual spectral data collected from the Stennis Space Center Diagnostic Test Facility rocket engine. The second paper included in this report investigates an analytical method for determining the cross sections for collision line broadening by molecular perturbers, using effective central force interaction potentials. These cross sections are determined for several atomic species with H2, one of the principal constituents of the SSME plume environment, and compared with experimental data.

  12. A Multi-Section Quantum-Dot Semiconductor Optical Amplifier for Ultrabroad-Band Gain-Flattened Low-Noise Amplification

    Institute of Scientific and Technical Information of China (English)

    Tomoyuki; Akiyama; Mitsuru; Sugawara; Koji; Otsubo; Hiroji; Ebe; Nobuaki; Hatori; Yasuhiko; Arakawa


    We propose an ultrabroad-band 1R regenerator utilizing a multi-section quantum-dot semiconductor optical amplifier. Due to the reduced electron states, quantum dot is beneficial in broadening the gain spectrum and lowering the noise figure. Combining this with a multi-section structure drastically improves the gain equality among the different bound states, leading to an increase in the maximum output power and an improvement of the noise figure.

  13. A Multi-Section Quantum-Dot Semiconductor Optical Amplifier for Ultrabroad-Band Gain-Flattened Low-Noise Amplification

    Institute of Scientific and Technical Information of China (English)

    Tomoyuki Akiyama; Mitsuru Sugawara; Koji Otsubo; Hiroji Ebe; Nobuaki Hatori; Yasuhiko Arakawa


    We propose an ultrabroad-band 1R regenerator utilizing a multi-section quantum-dot semiconductor optical amplifier.Due to the reduced electron states, quantum dot is beneficial in broadening the gain spectrum and lowering the noise figure. Combining this with a multi-section structure drastically improves the gain equality among the different bound states, leading to an increase in the maximum output power and an improvement of the noise figure.

  14. Unmyelinated visceral afferents exhibit frequency dependent action potential broadening while myelinated visceral afferents do not. (United States)

    Li, Bai-Yan; Feng, Bin; Tsu, Hwa Y; Schild, John H


    Sensory information arising from visceral organ systems is encoded into action potential trains that propagate along afferent fibers to target nuclei in the central nervous system. These information streams range from tight patterns of action potentials that are well synchronized with the sensory transduction event to irregular, patternless discharge with no clear correlation to the sensory input. In general terms these afferent pathways can be divided into unmyelinated and myelinated fiber types. Our laboratory has a long standing interest in the functional differences between these two types of afferents in terms of the preprocessing of sensory information into action potential trains (synchrony, frequency, duration, etc.), the reflexogenic consequences of this sensory input to the central nervous system and the ionic channels that give rise to the electrophysiological properties of these unique cell types. The aim of this study was to determine whether there were any functional differences in the somatic action potential characteristics of unmyelinated and myelinated vagal afferents in response to different rates of sensory nerve stimulation. Our results showed that activity and frequency-dependent widening of the somatic action potential was quite prominent in unmyelinated but not myelinated vagal afferents. Spike broadening often leads to increased influx of Ca(2+) ions that has been associated with a diverse range of modulatory mechanisms both at the cell body and central synaptic terminations (e.g. increased neurotransmitter release.) We conclude that our observations are indicative of fundamentally different mechanisms for neural integration of sensory information arising from unmyelinated and myelinated vagal afferents.

  15. A computational study of the role of spike broadening in synaptic facilitation of Hermissenda. (United States)

    Flynn, Mark; Cai, Yidao; Baxter, Douglas A; Crow, Terry


    Pavlovian conditioning in Hermissenda produces a decrease in voltage-dependent (I(K,A) and I(Ca)) and Ca2+-dependent (I(K,Ca)) currents, and an increase in the action potential (AP) duration in type B-photoreceptors. In addition, synaptic connections between B and A photoreceptors and B photoreceptor and type I interneurons are facilitated. The increase in AP duration, produced by decreasing one or more K+ currents, may account for synaptic facilitation. The present study examined this issue by using a mathematical model of the B-photoreceptor and the neurosimulator SNNAP. In the model, decreasing g(K,A) by 70% increased the duration of the AP in the terminal by 41% and Ca2+ influx by 30%. However, if the decrease in g(K,A) was combined with a decrease in g(Ca), similar to what has been reported experimentally, the Ca2+ influx decreased by 54%. Therefore, the concomitant change in I(Ca) counter-acted the broadening-induced increase in Ca2+ influx in the synaptic terminal. This result suggests that a spike-duration independent process must contribute to the synaptic facilitation observed following Pavlovian conditioning.

  16. Suppression of space broadening of exciton polariton transport by Bloch oscillation effect (United States)

    Duan, Xudong; Zou, Bingsuo; Zhang, Yongyou


    We theoretically study the transport of exciton polaritons under different applied photon potentials. The relation between the photon potentials and the thickness of the cavity layer is first calculated by finite-element simulation. The theoretical analysis and numerical calculation indicate that the cavity photon potential is proportional to the thickness of the cavity layer with the coefficient being about 1.8 meV nm-1. Further, the periodic and linear photon potentials are considered to control the transport of the exciton polaritons in weak- and strong-field pump situations. In both situations the periodic potential cannot by itself effectively suppress the scatterings of the disorder potentials of the cavity photons and excitons and the nonlinear exciton-exciton interaction. When the linear potential is added to the cavity photons, the exciton polariton transport exhibits the Bloch oscillation behavior. Importantly, the polariton Bloch oscillation can strongly suppress the space broadening of the exciton polariton transport due to the disorder potentials and nonlinear exciton-exciton interaction, which is beneficial for designing the polariton circuits.

  17. Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry (United States)


    Laser spectroscopy in the linear regime of radiation–matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

  18. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work

    Directory of Open Access Journals (Sweden)

    Annamaria eDi Fabio


    Full Text Available This article aims to broaden current reflections on definitions of decent work and poverty using a transdisciplinary interpretive lens comprising philosophical, juridical, economic, sociological, and psychological understandings. We (the authors undertook an adapted systematic qualitative review to gather data on different perspectives on decent work and poverty. The article summarizes and compares reflections on the two constructs and proposes an enhancement of the current definition of decent work. The aim is to facilitate the identification and development of new research and intervention projects that can be implemented to promote fair and sustainable economic development, the provision of decent work, and the reduction of poverty globally. We believe that challenges should be dealt with pro-actively rather than reactively and that intervening at the level of primary prevention should lie at the heart of any strategy to promote decent work and alleviate poverty. Radical intervention is needed to ensure that future generations not only survive but develop, grow, and express themselves meaningfully through decent work

  19. Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel (United States)

    Zhu, Huiping; Wang, Zhiguang; Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin; Li, Yuanfei; Wang, Ji; Song, Peng; Zhang, Peng; Cao, Xingzhong


    In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 1015 and 1.7 × 1016 ions/cm2. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

  20. Broadened immunity and protective responses with emulsion-adjuvanted H5 COBRA-VLP vaccines. (United States)

    Allen, James D; Owino, Simon O; Carter, Donald M; Crevar, Corey J; Reese, Valerie A; Fox, Christopher B; Coler, Rhea N; Reed, Steven G; Baldwin, Susan L; Ross, Ted M


    A number of challenges for developing a protective pre-pandemic influenza A vaccine exists including predicting the target influenza strain and designing the vaccine for an immunologically naïve population. Manufacturing and supply of the vaccine would also require implementing ways to increase coverage for the largest number of people through dose-sparing methods, while not compromising the potency of the vaccine. Previously, our group described a novel hemagglutinin (HA) for H5N1 influenza derived from a methodology termed computationally optimized broadly reactive antigen (COBRA). This report describes a strategy combining a COBRA-based HA vaccine with an oil-in-water emulsion, resulting in a dose-sparing, immunologically broadened, and protective response against multiple H5N1 isolates. Here, we show that an emulsion-based adjuvant enhances the magnitude and breadth of antibody responses with both a wild-type H5HA (H5N1 WT) and the H5N1 COBRA HA VLP vaccines. The H5N1 COBRA HA VLP, combined with an emulsion adjuvant, elicited HAI specific antibodies against a larger panel of H5N1 viruses that resulted in protection against challenge as efficiently as the homologous, matched vaccine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The HERMES recoil photon-detector and nuclear p{sub t}-Broadening at HERMES

    Energy Technology Data Exchange (ETDEWEB)

    Haarlem, Y. van


    The first part of this work consists of hardware research and development done in order to construct and test a photon-detector as one of the three detectors of the HERMES recoil detector. The HERMES recoil detector consists of a target cell, a silicon-detector, a scintillating fiber tracker, and a photon-detector. All are inside a super-conducting magnet. The silicon detector uses energy deposition to determine the momentum of the particle because in its energy range the energy deposition is an unambiguous function of the momentum of the particle. The scintillating fiber tracker is located outside the beam-vacuum and is surrounded by the photon-detector. It consists of two barrels with layers of scintillating fibers. It detects particles by converting their energy deposition into light. It measures two space points of a charged particle and from the bending of the assigned track (in the magnetic field provided by the super-conducting magnet) a momentum measurement can be derived. The photon-detector is located between the scintillating fiber tracker and the magnet. It consists (from the inside out) of three layers of tungsten showering material followed by scintillating strips. The second part of this work is an analysis performed concerning the transverse momentum broadening of hadrons produced in deep-inelastic scattering on a nuclear target compared to a D target. (orig.)

  2. Doppler Broadening Analysis of Steel Specimens Using Accelerator Based In Situ Pair Production (United States)

    Makarashvili, V.; Wells, D. P.; Roy, A. K.


    Positron Annihilation Spectroscopy (PAS) techniques can be utilized as a sensitive probe of defects in materials. Studying these microscopic defects is very important for a number of industries in order to predict material failure or structural integrity. We have been developing gamma-induced pair-production techniques to produce positrons in thick samples (˜4-40 g/cm2, or ˜0.5-5 cm in steel). These techniques are called 'Accelerator-based Gamma-induced Positron Annihilation Spectroscopy' (AG-PAS). We have begun testing the capabilities of this technique for imaging of defect densities in thick structural materials. As a first step, a linear accelerator (LINAC) was employed to produce photon beams by stopping 15 MeV electrons in a 1 mm thick tungsten converter. The accelerator is capable of operating with 30-60 ns pulse width, up to 200 mA peak current at 1 kHz repetition rate. The highly collimated bremsstrahlung beam impinged upon our steel tensile specimens, after traveling through a 1.2 m thick concrete wall. Annihilation radiation was detected by a well-shielded and collimated high-purity germanium detector (HPGe). Conventional Doppler broadening spectrometry (DBS) was performed to determine S, W and T parameters for our samples.

  3. Broadening the neutralizing capacity of a family of antibody fragments against different toxins from Mexican scorpions. (United States)

    Rodríguez-Rodríguez, Everardo Remi; Olamendi-Portugal, Timoteo; Serrano-Posada, Hugo; Arredondo-López, Jonathan Noé; Gómez-Ramírez, Ilse; Fernández-Taboada, Guillermo; Possani, Lourival D; Anguiano-Vega, Gerardo Alfonso; Riaño-Umbarila, Lidia; Becerril, Baltazar


    New approaches aimed at neutralizing the primary toxic components present in scorpion venoms, represent a promising alternative to the use of antivenoms of equine origin in humans. New potential therapeutics developed by these approaches correspond to neutralizing antibody fragments obtained by selection and maturation processes from libraries of human origin. The high sequence identity shared among scorpion toxins is associated with an important level of cross reactivity exhibited by these antibody fragments. We have exploited the cross reactivity showed by single chain variable antibody fragments (scFvs) of human origin to re-direct the neutralizing capacity toward various other scorpion toxins. As expected, during these evolving processes several variants derived from a parental scFv exhibited the capacity to simultaneously recognize and neutralize different toxins from Centruroides scorpion venoms. A sequence analyses of the cross reacting scFvs revealed that specific mutations are responsible for broadening their neutralizing capacity. In this work, we generated a set of new scFvs that resulted from the combinatorial insertion of these point mutations. These scFvs are potential candidates to be part of a novel recombinant antivenom of human origin that could confer protection against scorpion stings. A remarkable property of one of these new scFvs (ER-5) is its capacity to neutralize at least three different toxins and its complementary capacity to neutralize the whole venom from Centruroides suffusus in combination with a second scFv (LR), which binds to a different epitope shared by Centruroides scorpion toxins.

  4. Dams and Displacement: Raising the Standards and Broadening the Research Agenda

    Directory of Open Access Journals (Sweden)

    Brooke McDonald-Wilmsen


    Full Text Available The World Commission on Dams provided an analytical overview of the cumulative effects of years of dam development. A lack of commitment or capacity to cope with displacement or to consider the civil rights of, or risks to, displaced people led to the impoverishment and suffering of tens of millions and growing opposition to dams by affected communities worldwide. However, after the WCD, little has changed for the better in terms of resettlement policies. In fact, the standards of key agencies, like the Asian Development Bank, have been lowered and diluted compared to prior policies. Dam-induced development and displacement are stifled by a 'managerialist' approach to planning, in which solutions are sought internally and subordinated to the economics that underpins the existence of the project. The aim of successful resettlement is to prevent impoverishment and to enable displaced people to share in the project’s benefits. Within the field of dam-induced resettlement, this is a lofty goal rarely achieved. However, in other fields of resettlement, such as refugee studies and adaptation to environmental change, such a goal is regarded as a minimum standard. In this paper we seek to broaden the research agenda on dam-induced resettlement and to raise the standards of development projects that entail resettlement. We do this by importing some of the considerations and concerns from practice and research from the fields of refugee studies and adaptation to environmental change.

  5. Diagnosing galactic feedback with the line broadening in the low redshift Lyman-alpha forest

    CERN Document Server

    Viel, M; Bolton, J S; Kim, T -S; Puchwein, E; Nasir, F; Wakker, B P


    We compare the low redshift (z ~ 0.1) Lyman-alpha forest from hydrodynamical simulations with data from the Cosmic Origin Spectrograph (COS). We find tension between the observed number of lines with b-parameters in the range 25-45 km/s and the predictions from simulations that incorporate either vigorous feedback from active galactic nuclei or that exclude feedback altogether. The gas in these simulations is, respectively, either too hot to contribute to the Lyman-alpha absorption or too cold to produce the required line widths. Matching the observed b-parameter distribution therefore requires feedback processes that thermally or turbulently broaden the absorption features without collisionally (over-)ionising hydrogen. This suggests the Lyman-alpha forest b-parameter distribution is a valulable diagnostic of galactic feedback in the low redshift Universe. We furthermore confirm the low redshift Lyman-alpha forest column density distribution is better reproduced by an ultraviolet background with an HI photo-...

  6. Test of relativistic gravity using microlensing of relativistically broadened lines in gravitationally lensed quasars

    CERN Document Server

    Neronov, A


    We show that observation of the time-dependent effect of microlensing of relativistically broadened emission lines (such as e.g. the Fe Kalpha line in X-rays) in strongly lensed quasars could provide data on celestial mechanics of circular orbits in the direct vicinity of the horizon of supermassive black holes. This information can be extracted from the observation of evolution of red / blue edge of the magnified line just before and just after the period of crossing of the innermost stable circular orbit by the microlensing caustic. The functional form of this evolution is insensitive to numerous astrophysical parameters of the accreting black hole and of the microlensing caustics network system (as opposed to the evolution the full line spectrum). Measurement of the temporal evolution of the red / blue edge could provide a precision measurement of the radial dependence of the gravitational redshift and of velocity of the circular orbits, down to the innermost stable circular orbit. These measurements could...

  7. Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

    Energy Technology Data Exchange (ETDEWEB)

    Şahin, E; Hamid, R; Çelik, M [National Metrology Institute of Turkey, Gebze, Kocaeli (Turkey); Özen, G [Istanbul Technical University, Faculty of Science and Letters, Engineering Physics Department Maslak, Istanbul (Turkey); Izmailov, A Ch [Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid av. 33, Baku, Az-1143 (Azerbaijan)


    We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level Λ-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected Λ-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have established that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)

  8. Transverse Momentum Broadening of a Fast Quark in a $\\N=4$ Yang Mills Plasma

    CERN Document Server

    Casalderrey-Solana, J; Casalderrey-Solana, Jorge; Teaney, Derek


    We compute the momentum broadening of a heavy fundamental charge propagating through a $\\mathcal{N}=4$ Yang Mills plasma at large t' Hooft coupling. We do this by expressing the medium modification of the probe's density matrix in terms of a Wilson loop averaged over the plasma. We then use the AdS/CFT correspondence to evaluate this loop, by identifying the dual semi-classical string solution. The calculation introduces the type ``1'' and type ``2'' fields of the thermal field theory and associates the corresponding sources with the two boundaries of the AdS space containing a black hole. The transverse fluctuations of the endpoints of the string determine $\\kappa_T = \\sqrt{\\gamma \\lambda} T^3 \\pi$ -- the mean squared momentum transfer per unit time. ($\\gamma$ is the lorentz gamma factor of the quark.) The result reproduces previous results for the diffusion coefficient of a heavy quark. We compare our results with previous AdS/CFT calculations of $\\hat{q}$.

  9. Transverse momentum broadening of a fast quark in a Script N = 4 Yang-Mills plasma (United States)

    Casalderrey-Solana, Jorge; Teaney, Derek


    We compute the momentum broadening of a heavy fundamental charge propagating through a Script N = 4 Yang Mills plasma at large t' Hooft coupling. We do this by expressing the medium modification of the probe's density matrix in terms of a Wilson loop averaged over the plasma. We then use the AdS/CFT correspondence to evaluate this loop, by identifying the dual semi-classical string solution. The calculation introduces the type ``1'' and type ``2'' fields of the thermal field theory and associates the corresponding sources with the two boundaries of the AdS space containing a black hole. The transverse fluctuations of the endpoints of the string determine κT = (γλ)1/2T3π—the mean squared momentum transfer per unit time. (γ is the Lorentz gamma factor of the quark.) The result reproduces previous results for the diffusion coefficient of a heavy quark. We compare our results with previous AdS/CFT calculations of hat q.

  10. Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

    Energy Technology Data Exchange (ETDEWEB)

    Trela, W.J.; Kwei, G.H.; Lynn, J.E. [Los Alamos National Lab., NM (United States); Meggers, K. [Univ. of Kiel (Germany)


    Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phonons carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.

  11. Spectral-Kinetic Coupling and Effect of Microfield Rotation on Stark Broadening in Plasmas

    Directory of Open Access Journals (Sweden)

    Alexander V. Demura


    Full Text Available The study deals with two conceptual problems in the theory of Stark broadening by plasmas. One problem is the assumption of the density matrix diagonality in the calculation of spectral line profiles. This assumption is closely related to the definition of zero wave functions basis within which the density matrix is assumed to be diagonal, and obviously violated under the basis change. A consistent use of density matrix in the theoretical scheme inevitably leads to interdependence of atomic kinetics, describing the population of atomic states with the Stark profiles of spectral lines, i.e., to spectral-kinetic coupling. The other problem is connected with the study of the influence of microfield fluctuations on Stark profiles. Here the main results of the perturbative approach to ion dynamics, called the theory of thermal corrections (TTC, are presented, within which the main contribution to effects of ion dynamics is due to microfield fluctuations caused by rotations. In the present study the qualitative behavior of the Stark profiles in the line center within predictions of TTC is confirmed, using non-perturbative computer simulations.

  12. Line formation in Be star circumstellar disks Shear broadening, shell absorption, stellar obscuration and rotational parameter (United States)

    Hummel, W.; Vrancken, M.


    We improve the theory of Horne & Marsh on shear broadening in accretion disks of CVs and adapt it to Be star circumstellar disks. Stellar obscuration and shell absorption are taken into account in detail. It is shown that shell absorption is already present in those emission lines where the central depression does not drop below the stellar continuum. The model profiles are fitted to observed symmetric Hα net emission lines with low equivalent width. The derived disk radii range from Rd = 5.3 R_* to Rd = 18 R_* and the surface emissivity varies as ~ R-m with 1.6 (1)/(2) with the optically thick Hα profile of HR 5440 rules out the range of j>(1)/(2). This can be understood by the lack of velocity shear in the outer disk regions. We conclude that Keplerian rotation (j=(1)/(2)) is a valid approximation. Based on observations collected at the German-Spanish Astronomical Center (DSAZ), Calar Alto, operated by the Max-Plank-Institut für Astronomie Heidelberg jointly with the Spanish National Commission for Astronomy. Based on observations collected at the Observatoire de Haute-Provence (OHP), CNRS, France.

  13. The influence of coordinated defects on inhomogeneous broadening in cubic lattices (United States)

    Matheson, P. L.; Sullivan, Francis P.; Evenson, William E.


    The joint probability distribution function (JPDF) of electric field gradient (EFG) tensor components in cubic materials is dominated by coordinated pairings of defects in shells near probe nuclei. The contributions from these inner shell combinations and their surrounding structures contain the essential physics that determine the PAC-relevant quantities derived from them. The JPDF can be used to predict the nature of inhomogeneous broadening (IHB) in perturbed angular correlation (PAC) experiments by modeling the G 2 spectrum and finding expectation values for V zz and η. The ease with which this can be done depends upon the representation of the JPDF. Expanding on an earlier work by Czjzek et al. (Hyperfine Interact. 14, 189-194, 1983), Evenson et al. (Hyperfine Interact. 237, 119, 2016) provide a set of coordinates constructed from the EFG tensor invariants they named W 1 and W 2. Using this parameterization, the JPDF in cubic structures was constructed using a point charge model in which a single trapped defect (TD) is the nearest neighbor to a probe nucleus. Individual defects on nearby lattice sites pair with the TD to provide a locus of points in the W 1- W 2 plane around which an amorphous-like distribution of probability density grows. Interestingly, however, marginal, separable PDFs appear adequate to model IHB relevant cases. We present cases from simulations in cubic materials illustrating the importance of these near-shell coordinations.

  14. Recent Approaches for Broadening the Spectral Bandwidth in Resonant Cavity Optoelectronic Devices

    Directory of Open Access Journals (Sweden)

    Gun Wu Ju


    Full Text Available Resonant cavity optoelectronic devices, such as vertical cavity surface emitting lasers (VCSELs, resonant cavity enhanced photodetectors (RCEPDs, and electroabsorption modulators (EAMs, show improved performance over their predecessors by placing the active device structure inside a resonant cavity. The effect of the optical cavity, which allows wavelength selectivity and enhancement of the optical field due to resonance, allows the devices to be made thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. However, the narrow spectral bandwidth significantly reduces operating tolerances, which leads to severe problems in applications such as optical communication, imaging, and biosensing. Recently, in order to overcome such drawbacks and/or to accomplish multiple functionalities, several approaches for broadening the spectral bandwidth in resonant cavity optoelectronic devices have been extensively studied. This paper reviews the recent progress in techniques for wide spectral bandwidth that include a coupled microcavity, asymmetric tandem quantum wells, and high index contrast distributed Bragg-reflectors. This review will describe design guidelines for specific devices together with experimental considerations in practical applications.

  15. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work. (United States)

    Di Fabio, Annamaria; Maree, Jacobus G


    This article aims to broaden current reflections on definitions of decent work and poverty using a transdisciplinary interpretive lens comprising philosophical, juridical, economic, sociological, and psychological understandings. We (the authors) undertook an adapted systematic qualitative review to gather data on different perspectives on decent work and poverty. The article summarizes and compares reflections on the two constructs and proposes an enhancement of the current definition of decent work. The aim is to facilitate the identification and development of new research and intervention projects that can be implemented to promote fair and sustainable economic development, the provision of decent work, and the reduction of poverty globally. We believe that challenges should be dealt with pro-actively rather than reactively and that intervening at the level of primary prevention should lie at the heart of any strategy to promote decent work and alleviate poverty. Radical intervention is needed to ensure that future generations not only survive but develop, grow, and express themselves meaningfully through decent work.

  16. Stark Broadening Analysis Using Optical Spectroscopy of the Dense Plasma Focus (United States)

    Ross, Patrick; Bennett, Nikki; Dutra, Eric; Hagen, E. Chris; Hsu, Scott; Hunt, Gene; Koch, Jeff; Waltman, Tom; NSTec DPF Team


    To aid in validating numerical modeling of MA-class dense plasma focus (DPF) devices, spectroscopic measurements of the Gemini Dense Plasma Focus (DPF) were performed using deuterium and deuterium/dopant (argon/krypton) gas. The spectroscopic measurements were made using a fiber-coupled spectrometer and streak camera. Stark line-broadening analysis was applied to the deuterium beta emission (486 nm) in the region near the breakdown of the plasma and during the run-down and run-in phases of the plasma evolution. Densities in the range of 1e17 to low 1e18 cm-3 were obtained. These values are in agreement with models of the DPF performed using the LSP code. The spectra also show a rise and fall with time, indicative of the plasma sheath passing by the view port. Impurity features were also identified in the spectra which grew in intensity as the gas inside the DPF was discharged repeatedly without cycling. Implications of this impurity increase for D-T discharges (without fresh gas fills between every discharge) will be discussed. This work was done by National Security Technologies, LLC, under Contract No. DE-AC52-06NA25946, and by Los Alamos National Laboratory, under Contract no. DE-AC52-06NA25396 with the U.S. Department of Energy. DOE/NV/25946-2515.

  17. Perceived workplace harassment experiences and problem drinking among physicians: broadening the stress/alienation paradigm. (United States)

    Richman, J A; Flaherty, J A; Rospenda, K M


    Sociologists who embrace the stress or alienation paradigms generally focus on explaining problem drinking in low status occupations. By contrast, this paper argues that a broadened conceptualization of stress and alienation which incorporates abusive work relationships has utility for explaining male and female drinking outcomes in both high and low status occupations. We provide empirical data on the relationship between perceived abusive experiences and drinking outcomes in a cohort of male and female physicians in their internship year of training. The data show that perceived sexual harassment, discriminatory treatment and psychological humiliation relate to various drinking outcomes in men and women, controlling for drinking prior to the internship year. While females were more likely to report experiencing abuse, these perceived experiences had deleterious effects on drinking outcomes for both genders. Personal vulnerability (narcissism) brought into the training environment somewhat influenced the later reporting of abusive experiences by males but not by females. Regression analyses showed that, for both males and females, work-place abusive experiences in interaction with personality vulnerability best explained drinking outcomes. The implications of these results for the design of future alcohol-related work-place studies are discussed.

  18. Broadening perspectives on trauma and recovery: a socio-interpersonal view of PTSD†

    Directory of Open Access Journals (Sweden)

    Andreas Maercker


    Full Text Available Posttraumatic stress disorder (PTSD is one of the very few mental disorders that requires by definition an environmental context—a traumatic event or events—as a precondition for diagnosis. Both trauma sequelae and recovery always occur in the context of social–interpersonal contexts, for example, in interaction with a partner, family, the community, and the society. The present paper elaborates and extends the social–interpersonal framework model of PTSD. This was developed to complement other intrapersonally focused models of PTSD, which emphasize alterations in an individual's memory, cognitions, or neurobiology. Four primary reasons for broadening the perspective from the individual to the interpersonal–societal contexts are discussed. The three layers of the model (social affects, close relationships, and culture and society are outlined. We further discuss additional insights and benefits of the social–interpersonal perspective for the growing field of research regarding resilience after traumatic experiences. The paper closes with an outlook on therapy approaches and interventions considering this broader social–interpersonal perspective on PTSD.

  19. Helium implanted Eurofer97 characterized by positron beam Doppler broadening and Thermal Desorption Spectroscopy (United States)

    Carvalho, I.; Schut, H.; Fedorov, A.; Luzginova, N.; Desgardin, P.; Sietsma, J.


    Reduced Activation Ferritic/Martensitic steels are being extensively studied because of their foreseen application in fusion and Generation IV fission reactors. To produce irradiation induced defects, Eurofer97 samples were implanted with helium at energies of 500 keV and 2 MeV and doses of 1 × 1015-1016 He/cm2, creating atomic displacements in the range 0.07-0.08 dpa. The implantation induced defects were characterized by positron beam Doppler Broadening (DB) and Thermal Desorption Spectroscopy (TDS). Results show that up to ˜600 K peaks that can be attributed to He desorption from overpressured HenVm (n > m) clusters and vacancy assisted mechanism in the case of helium in the substitutional position. The temperature range 600-1200 K is related to the formation of larger clusters HenVm (n < m). The dissociation of the HeV and the phase transition attributed to a sharp peak in the TDS spectra at 1200 K. Above this temperature, the release of helium from bubbles is observed.

  20. [Analysis of lorentzian line shape function broadened by non-sinusoidal wavelength modulation]. (United States)

    Sun, You-Qun; Wang, Yun-Tao; Ruan, Chi; Xu, Song-Song


    In the present work, the Fourier analysis of Lorentzian line shape broadened by non-sinusoidal wavelength modulation was investigated, in which the third order and above harmonic items were ignored. The analytical expression of n-order Fourier coefficient was brought out, where a variable K named harmonic distortion to characterize the ratio of the second harmonic to the first harmonic was introduced. Numerical simulations based on the cases of K > 0.01 and K 0.01, the effect of different depths of modulation on the odd and even order harmonic amplitude curve is significant. And the numerical simulation shows there exists an optimum value of modulation depth which could minimize the impact of the harmonic distortion, and both large K value and small K value would cause a great error. The conclusion of this work could be applied in error analysis of wavelength modulation spectroscopy system And the results are helpful to deepening understanding of WMS and would be the important reference for some kind of frequency stabilization technology in laser instrument.

  1. Intracorporeal Suturing and Knot Tying Broadens the Clinical Applicability of Laparoscopy (United States)

    Rivas, Homero; Cacchione, Robert N.; Ferzli, George S.


    Objective: As surgeons become more experienced with basic laparoscopic procedures like cholecystectomy, they are able to expand this approach to less common operations. However, without laparoscopic suturing skills, like those obtained with Nissen fundoplication, many operations cannot be completed laparoscopically. We present a series of 10 patients with less common surgical illnesses who were successfully treated with minimal access techniques and intracorporeal suturing. Methods: Over a 6-month period at 2 medical centers, 10 patients underwent operations with laparoscopic intracorporeal suturing and knot tying. Diagnoses included bowel obstruction due to gallstone ileus (n=1), perforated uterus from an intrauterine device (n=1), urinary bladder diverticulum (n=1), bleeding Meckel's diverticulum (n=3), and perforated duodenal ulcer (n=4). Results: Each patient was treated with standard surgical interventions performed entirely laparoscopically with intracorporeal suturing. No morbidity or mortality occurred in any patient due to the operation. Conclusions: Although each of these operations has been previously reported, as a series, they point out the importance of mastering laparoscopic suturing. Although devices are commercially available to facilitate certain suturing scenarios, we encourage residents and fellows to sew manually. We believe that none of these operations could have been completed as effectively by using a suture device. The ability to suture laparoscopically markedly broadens the number of clinical scenarios in which minimal access techniques can be used. PMID:12856844

  2. Broadening the trans-contextual model of motivation: A study with Spanish adolescents. (United States)

    González-Cutre, D; Sicilia, Á; Beas-Jiménez, M; Hagger, M S


    The original trans-contextual model of motivation proposed that autonomy support from teachers develops students' autonomous motivation in physical education (PE), and that autonomous motivation is transferred from PE contexts to physical activity leisure-time contexts, and predicts attitudes, perceived behavioral control and subjective norms, and forming intentions to participate in future physical activity behavior. The purpose of this study was to test an extended trans-contextual model of motivation including autonomy support from peers and parents and basic psychological needs in a Spanish sample. School students (n = 400) aged between 12 and 18 years completed measures of perceived autonomy support from three sources, autonomous motivation and constructs from the theory of planned behavior at three different points in time and in two contexts, PE and leisure-time. A path analysis controlling for past physical activity behavior supported the main postulates of the model. Autonomous motivation in a PE context predicted autonomous motivation in a leisure-time physical activity context, perceived autonomy support from teachers predicted satisfaction of basic psychological needs in PE, and perceived autonomy support from peers and parents predicted need satisfaction in leisure-time. This study provides a cross-cultural replication of the trans-contextual model of motivation and broadens it to encompass basic psychological needs.

  3. Transformational Partnerships and Learning: broadening the experiences for a community organization, school and university

    Directory of Open Access Journals (Sweden)

    Janette Long


    Full Text Available Partnerships between community organizations, schools and universities are becoming more widespread as education faculties seek to broaden the experiences of their preservice teachers (Kruger, Davies, Eckersley, Newell& Cherednichenko, 2009. The following paper reports on one such endeavour where a small group of six preservice teachers, drawn from teaching programs that included secondary, primary and primary/early childhood, were immersed in a primary/secondary rural school in Sola, on the remote island of Vanua Lava, located in the northern province of Vanuatu. Whilst international practicums are not new, what is unique within this endeavour was the nature of the partnership that included the Vanuatu Ministry of Education, the Australian Catholic University (ACU and Rotary Australia World Community Service (RAWCS. Each partner had a layer of active participants represented by Arep Secondary School, the School of Education (ACU, NSW, and the Rotary Club of Winston Hills.  The partnership was therefore able to provide both strategic and practical support to the ongoing project, creating layers of engagement and participation for the various groups.  This partnership was transformational as it was based upon genuine engagement with a focus on common goals and mutual benefits, built on relationships established over many years, which is different to other types of partnerships that often seek to obtain only individual organizational goals rather that mutual goals or shared purposes (Brown et al., 2006.

  4. Fabrication of a 2-DOF electromagnetic energy harvester with in-phase vibrational bandwidth broadening (United States)

    Chen, Shih-Jui; Wu, Jia-Yin


    A vibration structure with two-degrees-of-freedom is proposed to increase the usable bandwidth of a micromachined electromagnetic energy harvester. Compared with the structure of a pure cantilever harvester, the proposed structure is formed by integrating a spiral diaphragm into a U-shaped cantilever diaphragm. By performing finite element analysis, the resonance frequencies of the two diaphragms are designed with a slight shift, both lower than 300 Hz. In addition, to achieve output bandwidth broadening, electroplated copper coils on the spiral and the U-shaped cantilever are coupled and the connection sequences of the coupled coils are arranged such that single- or duo-mode tuning of the energy harvester can be realized. The harvester delivers powers of 22.1 and 21.5 nW at two resonance frequencies of 211 and 274 Hz, respectively, in the duo-mode operation. The proposed spiral-cantilever coupled energy harvester has lower resonance frequencies and broader bandwidth than a pure cantilever-type harvester of equal area, and can therefore harvest more energy from the environment.

  5. Scatter Broadening of Pulsars and Implications on the Interstellar Medium Turbulence (United States)

    Xu, Siyao; Zhang, Bing


    Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of electron density fluctuations consisting of not only a Kolmogorov density spectrum but also a short-wave-dominated density spectrum with the density structure formed at small scales due to shocks. The resulting dependence of the scatter broadening time on the dispersion measure (DM) naturally interprets the existing observational data for both low- and high-DM pulsars. According to the criteria that we derive for a quantitative determination of scattering regimes over wide ranges of DMs and frequencies ν, we find that the pulsars with low DMs are primarily scattered by the Kolmogorov turbulence, while those at low Galactic latitudes with high DMs undergo more enhanced scattering dominated by the supersonic turbulence, where the corresponding density spectrum has a spectral index of ≈ 2.6. Furthermore, by considering a volume filling factor of the density structures with the dependence on ν as \\propto {ν }1.4 in the supersonic turbulence, our model can also explain the observed shallower ν scaling of the scattering time than the Kolmogorov scaling for the pulsars with relatively large DMs. The comparison between our analytical results and the scattering measurements of pulsars in turn makes a useful probe of the properties of the large-scale ISM turbulence, e.g., an injection scale of ∼100 pc, and also characteristics of small-scale density structures.

  6. Broadening not strengthening of the Agulhas Current since the early 1990s (United States)

    Beal, Lisa M.; Elipot, Shane


    Western boundary currents—such as the Agulhas Current in the Indian Ocean—carry heat poleward, moderating Earth’s climate and fuelling the mid-latitude storm tracks. They could exacerbate or mitigate warming and extreme weather events in the future, depending on their response to anthropogenic climate change. Climate models show an ongoing poleward expansion and intensification of the global wind systems, most robustly in the Southern Hemisphere, and linear dynamical theory suggests that western boundary currents will intensify and shift poleward as a result. Observational evidence of such changes comes from accelerated warming and air-sea heat flux rates within all western boundary currents, which are two or three times faster than global mean rates. Here we show that, despite these expectations, the Agulhas Current has not intensified since the early 1990s. Instead, we find that it has broadened as a result of more eddy activity. Recent analyses of other western boundary currents—the Kuroshio and East Australia currents—hint at similar trends. These results indicate that intensifying winds may be increasing the eddy kinetic energy of boundary currents, rather than their mean flow. This could act to decrease poleward heat transport and increase cross-frontal exchange of nutrients and pollutants between the coastal ocean and the deep ocean. Sustained in situ measurements are needed to properly understand the role of these current systems in a changing climate.

  7. Familial band-shaped keratopathy. (United States)

    Ticho, U; Lahav, M; Ivry, M


    A brother and sister out of a consanguinous family of four siblings are presented as prototypes of primary band-shaped keratopathy. The disease manifested sever progressive changes of secondary nature over two years of follow-up. Histology and treatment are described.


    DEFF Research Database (Denmark)


    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction...

  9. Metaphyseal bands in osteogenesis imperfecta

    Directory of Open Access Journals (Sweden)

    Suresh S


    Full Text Available An increasing number of patients with osteogenesis imperfecta are undergoing pamidronate therapy to prevent the incidence of fragility fractures. The authors herein report a child aged 3 years who received five cycles of pamidronate, resulting in metaphyseal bands, known as "zebra lines."

  10. Bands for girls and boys

    Institute of Scientific and Technical Information of China (English)



    Like many people, you may be dreaming of a career(职业) as rock and roll stars. There are two ways to go about getting one. First is the traditional way. Find some friends and form a group. Learn to play the guitar or the drums. Write your own songs. Spend hours arguing about the band name. Then go out on the road.

  11. K-Band Latching Switches (United States)

    Piotrowski, W. S.; Raue, J. E.


    Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

  12. K-band latching switches (United States)

    Piotrowski, W. S.; Raue, J. E.


    Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

  13. Doppler broadening thermometry of acetylene and accurate measurement of the Boltzmann constant. (United States)

    Hashemi, R; Povey, C; Derksen, M; Naseri, H; Garber, J; Predoi-Cross, A


    In this paper, we present accurate measurements of the fundamental Boltzmann constant based on a line-shape analysis of acetylene spectra in the ν1 + ν3 band recorded using a tunable diode laser. Experimental spectra recorded at low pressures (0.25 - 9 Torr), have been analyzed using a Speed Dependent Voigt model that takes into account the molecular speed dependence effects. This line-shape model reproduces the experimental data with good accuracy and allows us to determine precise line-shape parameters for the P(25) transition of the ν1 + ν3 band. From the recorded spectra we obtained the Doppler-width and then determined the Boltzmann constant, k(B).

  14. Assessing and Broadening Genetic Diversity of Elymus sibiricus Germplasm for the Improvement of Seed Shattering

    Directory of Open Access Journals (Sweden)

    Zongyu Zhang


    Full Text Available Siberian wild rye (Elymus sibiricus L. is an important native grass in the Qinghai-Tibet Plateau of China. It is difficult to grow for commercial seed production, since seed shattering causes yield losses during harvest. Assessing the genetic diversity and relationships among germplasm from its primary distribution area contributes to evaluating the potential for its utilization as a gene pool to improve the desired agronomic traits. In the study, 40 EST-SSR primers were used to assess the genetic diversity and population structure of 36 E. sibiricus accessions with variation of seed shattering. A total of 380 bands were generated, with an average of 9.5 bands per primer. The polymorphic information content (PIC ranged from 0.23 to 0.50. The percentage of polymorphic bands (P for the species was 87.11%, suggesting a high degree of genetic diversity. Based on population structure analysis, four groups were formed, similar to results of principal coordinate analysis (PCoA. The molecular variance analysis (AMOVA revealed the majority of genetic variation occurred within geographical regions (83.40%. Two genotypes from Y1005 and ZhN06 were used to generate seven F1 hybrids. The molecular and morphological diversity analysis of F1 population revealed rich genetic variation and high level of seed shattering variation in F1 population, resulting in significant improvement of the genetic base and desired agronomic traits.

  15. Statistical correlation of spectral broadening in VLF transmitter signal and low-frequency ionospheric turbulence from observation on DEMETER satellite

    Directory of Open Access Journals (Sweden)

    A. Rozhnoi


    Full Text Available In our earlier papers we have found the effect of VLF transmitter signal depression over epicenters of the large earthquakes from observation on the French DEMETER satellite that can be considered as new method of global diagnostics of seismic influence on the ionosphere. At present paper we investigate a possibility VLF signal-ionospheric turbulence interaction using additional characteristic of VLF signal-spectrum broadening. This characteristic is important for estimation of the interaction type: linear or nonlinear scattering. Our main results are the following:
    – There are two zones of increased spectrum broadening, which are centered near magnetic latitudes Φ=±10° and Φ=±40°. Basing on the previous case study research and ground ionosonde registrations, probably it is evidence of nonlinear (active scattering of VLF signal on the ionospheric turbulence. However occurrence rate of spectrum broadening in the middle-latitude area is higher than in the near-equatorial zone (~15–20% in comparison with ~100% in former area that is probably coincides with the rate of ionospheric turbulence.
    – From two years statistics of observation in the selected 3 low-latitude regions and 1 middle-latitude region inside reception area of VLF signal from NWC transmitter we find a correlation of spectrum broadening neither with ion-cyclotron noise (f=150–500 Hz, which possibly means poor representation of the turbulence by the noise due to its mixture with natural ELF emission (which correlates with whistler, nor with magnetic storm activity.
    – We find rather evident correlation of ion-cyclotron frequency noise, VLF signal depression and weak correlation of spectrum broadening with seismicity in the middle-latitude region over Japan. But in the low-latitude regions we do not find such a correlation. Statistical decrease of VLF signal supports our previous case study results. However rather weak spectrum broadening

  16. Slimming down: Small rotary steerable systems broaden directional market. Are shallow gas wells next?

    Energy Technology Data Exchange (ETDEWEB)

    Roche, P.


    Drilling an offshore well in an environmentally sensitive area just off the southern coast of England is described. Instead of building an artificial island, BP decided to use a new technology and drill the well from shore. The technique is known as extended-reach drilling; one of the wells in the field had a measured total depth of 37,001 feet, more than eleven kilometres. The technology that made this well possible is known as rotary steerable drilling. The technology is expensive, but the field has an estimated 447 million barrels of recoverable oil, and very prolific individual wells, hence economically justifiable. The technology is most suited to expensive offshore wells, but developers of rotary steerable systems -- Schlumberger Oilfield Services and Precision Drilling Corporation -- believe that the slim-hole tools they are developing have broadened the market to include smaller operators drilling less-costly onshore wells. Experts predict that the system eventually could be economic even on shallow-gas wells in Western Canada. The two service companies have steerable systems that drill six-inch boreholes, and Schlumberger is currently working on a system to drill four and a half inch holes. The smaller diameter rotary steerable systems have a great future in draining smaller oil pools that would not be economical if pools had to linked with conventional eight and a half inch boreholes. The prime example is Shell Exploration and Production of Britain, a drilling contractor that has been successfully using slim-hole systems in its North Sea operations to drill wells that would not otherwise get drilled. Although the rotary steerable business currently is concentrated in southwestern England, slim-hole systems have also been used in other mature fields in the Gulf of Mexico, Norway and even the Middle East and the Far East.


    Energy Technology Data Exchange (ETDEWEB)

    Deen, Casey P. [Max Planck Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg, GermanyAND (Germany); Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712 (United States)


    In an attempt to widen access to the study of magnetic fields in stellar astronomy, I present MOOGStokes, a version of the MOOG one-dimensional local thermodynamic equilibrium radiative transfer code, overhauled to incorporate a Stokes vector treatment of polarized radiation through a magnetic medium. MOOGStokes is a suite of three complementary programs, which together can synthesize the disk-averaged emergent spectrum of a star with a magnetic field. The first element (a pre-processing script called CounterPoint) calculates for a given magnetic field strength, wavelength shifts, and polarizations for the components of Zeeman-sensitive lines. The second element (a MOOG driver called SynStokes derived from the existing MOOG driver Synth) uses the list of Zeeman-shifted absorption lines together with the existing machinery of MOOG to synthesize the emergent spectrum at numerous locations across the stellar disk, accounting for stellar and magnetic field geometry. The third and final element (a post-processing script called DiskoBall) calculates the disk-averaged spectrum by weighting the individual emergent spectra by limb darkening and projected area, and applying the effects of Doppler broadening. All together, the MOOGStokes package allows users to synthesize emergent spectra of stars with magnetic fields in a familiar computational framework. MOOGStokes produces disk-averaged spectra for all Stokes vectors ( I, Q, U, V ), normalized by the continuum. MOOGStokes agrees well with the predictions of INVERS10 a polarized radiative transfer code with a long history of use in the study of stellar magnetic fields. In the non-magnetic limit, MOOGStokes also agrees with the predictions of the scalar version of MOOG.

  18. A New Norm: Using Social Science to Create Disruptive Innovations for Broadening Participation in Physics (United States)

    Smith, Jessi L.


    Norms often operate outside conscious awareness and limit broad participation in physics and STEM fields more generally. This presentation identifies several of these norms and provides empirically tested disruptions at three academic points: faculty, graduate, and undergraduate. First, is a focus on broadening the participation of women science faculty through an intervention aimed at supporting faculty search committees. Using a randomized control trail design, results show searches in the intervention were 6.3 times more likely to make an offer to a woman candidate, and these women were 5.8 times more likely to accept the offer from an intervention search. A diverse faculty can help disrupt the norms of their field's understanding about brilliance and effort, which can appeal to -or repel- potential graduate students. Using a randomized control trial design, recruitment materials for a science graduate program were manipulated to emphasize effort versus innate ability as the norm. Results show emphasizing effort as normal to achieve success in the male-dominated graduate program elevated women's motivation to purse and persist in graduate studies. Of course, before a student will consider graduate school, they must see themselves as a scientist. Data from a survey at three universities showed undergraduate women in physics lab classes were less likely to identify as a scientist when they were concerned about being stereotyped and could not see how physics was useful or helpful to society. Identifying and disrupting social norms can help create an inclusive learning and working context with far-reaching benefits. National Science Foundation Award HRD-1208831 and HRD-1036767.

  19. Charge Carrier Hopping Dynamics in Homogeneously Broadened PbS Quantum Dot Solids. (United States)

    Gilmore, Rachel H; Lee, Elizabeth M Y; Weidman, Mark C; Willard, Adam P; Tisdale, William A


    Energetic disorder in quantum dot solids adversely impacts charge carrier transport in quantum dot solar cells and electronic devices. Here, we use ultrafast transient absorption spectroscopy to show that homogeneously broadened PbS quantum dot arrays (σhom(2):σinh(2) > 19:1, σinh/kBT quantum dot batches are sufficiently monodisperse (δ ≲ 3.3%). The homogeneous line width is found to be an inverse function of quantum dot size, monotonically increasing from ∼25 meV for the largest quantum dots (5.8 nm diameter/0.92 eV energy) to ∼55 meV for the smallest (4.1 nm/1.3 eV energy). Furthermore, we show that intrinsic charge carrier hopping rates are faster for smaller quantum dots. This finding is the opposite of the mobility trend commonly observed in device measurements but is consistent with theoretical predictions. Fitting our data to a kinetic Monte Carlo model, we extract charge carrier hopping times ranging from 80 ps for the smallest quantum dots to over 1 ns for the largest, with the same ethanethiol ligand treatment. Additionally, we make the surprising observation that, in slightly polydisperse (δ ≲ 4%) quantum dot solids, structural disorder has a greater impact than energetic disorder in inhibiting charge carrier transport. These findings emphasize how small improvements in batch size dispersity can have a dramatic impact on intrinsic charge carrier hopping behavior and will stimulate further improvements in quantum dot device performance.

  20. Broadened population-level frequency tuning in human auditory cortex of portable music player users.

    Directory of Open Access Journals (Sweden)

    Hidehiko Okamoto

    Full Text Available Nowadays, many people use portable players to enrich their daily life with enjoyable music. However, in noisy environments, the player volume is often set to extremely high levels in order to drown out the intense ambient noise and satisfy the appetite for music. Extensive and inappropriate usage of portable music players might cause subtle damages in the auditory system, which are not behaviorally detectable in an early stage of the hearing impairment progress. Here, by means of magnetoencephalography, we objectively examined detrimental effects of portable music player misusage on the population-level frequency tuning in the human auditory cortex. We compared two groups of young people: one group had listened to music with portable music players intensively for a long period of time, while the other group had not. Both groups performed equally and normally in standard audiological examinations (pure tone audiogram, speech test, and hearing-in-noise test. However, the objective magnetoencephalographic data demonstrated that the population-level frequency tuning in the auditory cortex of the portable music player users was significantly broadened compared to the non-users, when attention was distracted from the auditory modality; this group difference vanished when attention was directed to the auditory modality. Our conclusion is that extensive and inadequate usage of portable music players could cause subtle damages, which standard behavioral audiometric measures fail to detect in an early stage. However, these damages could lead to future irreversible hearing disorders, which would have a huge negative impact on the quality of life of those affected, and the society as a whole.

  1. Positron annihilation Doppler broadening spectroscopy study on Fe-ion irradiated NHS steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Huiping [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zhiguang, E-mail: [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Gao, Xing; Cui, Minghuan; Li, Bingsheng; Sun, Jianrong; Yao, Cunfeng; Wei, Kongfang; Shen, Tielong; Pang, Lilong; Zhu, Yabin [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Yuanfei; Wang, Ji [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); University of Lanzhou, Lanzhou 730000 (China); Song, Peng [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Peng; Cao, Xingzhong [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)


    Highlights: • NHS steel was irradiated by 3.25 MeV Fe ions to different fluences at room temperature and 723 K. • The evolution of vacancy type defects is studied through positron annihilation spectroscopy. • The concentration gradient of SIA can induce the decrease of S value with increasing fluence at high temperature. - Abstract: In order to study the evolution of irradiation-induced vacancy-type defects at different irradiation fluences and temperatures, a new type of ferritic/martensitic (F/M) steel named NHS (Novel High Silicon) was irradiated by 3.25 MeV Fe-ion at room temperature and 723 K to fluences of 4.3 × 10{sup 15} and 1.7 × 10{sup 16} ions/cm{sup 2}. After irradiation, vacancy-type defects were investigated with variable-energy positron beam Doppler broadening spectra. Energetic Fe-ions produced a large number of vacancy-type defects in the NHS steel, but one single main type of vacancy-type defect was observed in both unirradiated and irradiated samples. The concentration of vacancy-type defects decreased with increasing temperature. With the increase of irradiation fluence, the concentration of vacancy-type defects increased in the sample irradiated at RT, whereas for the sample irradiated at 723 K, it decreased. The enhanced recombination between vacancies and excess interstitial Fe atoms from deeper layers, and high diffusion rate of self-interstitial atoms further improved by diffusion via grain boundary and dislocations at high temperature, are thought to be the main reasons for the reversed trend of vacancy-type defects between the samples irradiated at RT and 723 K.

  2. An International Coastline Collaboratory to Broaden Scientific Impacts of a Subduction Zone Observatory (United States)

    Bodin, P.


    A global Subduction Zone Observatory (SZO) presents an exciting opportunity to broaden involvement in scientific research and to ensure multidisciplinary impact. Most subduction zones feature dynamic interactions of the seafloor, the coastline, and the onshore environments also being perturbed by global climate change. Tectonic deformation, physical environment changes (temperature and chemistry), and resulting ecological shifts (intertidal population redistribution, etc.) are all basic observables for important scientific investigation. Yet even simple baseline studies like repeated transects of intertidal biological communities are rare. A coordinated program of such studies would document the local variability across time and spatial scales, permit comparisons with other subducting coastlines, and extend the reach and importance of other SZO studies. One goal is to document the patterns, and separate the component causes of, coastal uplift and subsidence and ecological response to a subduction zone earthquake using a database of pre-event biological and surveying observations. Observations would be directed by local scientists using students and trained volunteers as observers, under the auspices of local educational entities and using standardized sampling and reporting methods. The observations would be added to the global, Internet-accessible, database for use by the entire scientific community. Data acquisition and analysis supports the educational missions of local schools and universities, forming the basis for educational programs. All local programs would be coordinated by an international panel convened by the SZO. The facility would include a web-hosted lecture series and an annual web conference to aid organization and collaboration. Small grants could support more needy areas. This SZO collaboratory advances not only scientific literacy, but also multinational collaboration and scholarship, and (most importantly) produces important scientific results.

  3. The NIRSPEC Brown Dwarf Spectroscopic Survey II: High-Resolution J-Band Spectra of M, L and T Dwarfs

    CERN Document Server

    McLean, I S; McGovern, M R; Burgasser, A J; Kirkpatrick, J D; Rice, E L; Kim, S S; Lean, Ian S. Mc; Govern, Mark R. Mc; Burgasser, Adam J.; Rice, Emily L.; Kim, Sungsoo S.


    We present a sequence of high resolution (R~20,000 or 15 km/s) infrared spectra of stars and brown dwarfs spanning spectral types M2.5 to T6. Observations of 16 objects were obtained using eight echelle orders to cover part of the J-band from 1.165-1.323 micron with NIRSPEC on the Keck II telescope. By comparing opacity plots and line lists, over 200 weak features in the J-band are identified with either FeH or H2O transitions. Absorption by FeH attains maximum strength in the mid-L dwarfs, while H2O absorption becomes systematically stronger towards later spectral types. Narrow resolved features broaden markedly after the M to L transition. Our high resolution spectra also reveal that the disappearance of neutral Al lines at the boundary between M and L dwarfs is remarkably abrupt, presumably because of the formation of grains. Neutral Fe lines can be traced to mid-L dwarfs before Fe is removed by condensation. The neutral potassium (K I) doublets that dominate the J-band have pressure broadened wings that c...

  4. ALMA Band 5 Cartridge Performance (United States)

    Billade, Bhushan; Lapkin, I.; Nystrom, O.; Sundin, E.; Fredrixon, M.; Finger, R.; Rashid, H.; Desmaris, V.; Meledin, D.; Pavolotsky, A.; Belitsky, Victor


    Work presented here concerns the design and performance of the ALMA Band 5 cold cartridge, one of the 10 frequency channels of ALMA project, a radio interferometer under construction at Atacama Desert in Chile. The Band 5 cartridge is a dual polarization receiver with the polarization separation performed by orthomode transducer (OMT). For each polarization, Band 5 receiver employs sideband rejection (2SB) scheme based on quadrature layout, with SIS mixers covering 163-211 GHz with 4-8 GHz IF. The LO injection circuitry is integrated with mixer chip and is implemented on the same substrate, resulting in a compact 2SB assembly. Amongst the other ALMA bands, the ALMA Band 5 being the lowest frequency band that uses all cold optics, has the largest mirror. Consequently, ALMA Band 5 mirror along with its support structure leaves very little room for placing OMT, mixers and IF subsystems. The constraints put by the size of cold optics and limited cartridge space, required of us to revise the original 2SB design and adopt a design where all the components like OMT, mixer, IF hybrid, isolators and IF amplifier are directly connected to each other without using any co-ax cables in-between. The IF subsystem uses the space between 4 K and 15 K stage of the cartridge and is thermally connected to 4 K stage. Avoiding co-ax cabling required use of custom designed IF hybrid, furthermore, due to limited cooling capacity at 4 K stage, resistive bias circuitry for the mixers is moved to 15 K stage and the IF hybrid along with an integrated bias-T is implemented using superconducting micro-strip lines. The E-probes for both LO and RF waveguide-to-microstrip transitions are placed perpendicular to the wave direction (back-piece configuration). The RF choke at the end of the probes provides a virtual ground for the RF/LO signal, and the choke is DC grounded to the chassis. The on-chip LO injection is done using a microstrip line directional coupler with slot-line branches in the

  5. Polarization and angle insensitive dual-band bandpass frequency selective surface using all-dielectric metamaterials (United States)

    Yu, Fei; Wang, Jun; Wang, Jiafu; Ma, Hua; Du, Hongliang; Xu, Zhuo; Qu, Shaobo


    In this paper, we demonstrate a dual-band bandpass all-dielectric frequency selective surface (FSS), the building elements of which are high-permittivity ceramic particles rather than metallic patterns. With proper structural design and parameter adjustment, the resonant frequency can be tuned at will. Dual-band bandpass response can be realized due to the coupling between electric and magnetic resonances. As an example, a dual-band bandpass FSS is designed in Ku band, which is composed of two-dimensional periodic arrays of complementary quatrefoil structures (CQS) cut from dielectric plates. Moreover, cylindrical dielectric resonators are introduced and placed in the center of each CQS to broaden the bandwidth and to sharpen the cut-off frequency. Theoretical analysis shows that the bandpass response arises from impedance matching caused by electric and magnetic resonances. In addition, effective electromagnetic parameters and dynamic field distributions are presented to explain the mechanism of impedance matching. The proposed FSS has the merits of polarization independence, stable transmission, and sharp roll-off frequency. The method can also be used to design all-dielectric FSSs with continuum structures at other frequencies.

  6. Broad-Band Spectroscopy of Hercules X-1 with Suzaku (United States)

    Asami, Fumi; Enoto, Teruaki; Iwakiri, Wataru; Yamada, Shin'ya; Tamagawa, Toru; Mihara, Tatehiro; Nagase, Fumiaki


    Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4- 100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered a stable and intrinsic spectral feature in Her X-1. The broad hump lacked a sharp structure like an absorption edge. Thus it was represented by two different spectral models: an ionized partial covering or an additional broad line at 6.5 keV. The former required a persistently existing ionized absorber, whose origin was unclear. In the latter case, the Gaussian fitting of the 6.5-keV line needs a large width of sigma = 1.0-1.5 keV and a large equivalent width of 400-900 eV. If the broad line originates from Fe fluorescence of accreting matter, its large width may be explained by the Doppler broadening in the accretion flow. However, the large equivalent width may be inconsistent with a simple accretion geometry.

  7. Broad-Band Spectroscopy of Hercules X-1 with Suzaku (United States)

    Asami, Fumi; Enoto, Teruaki; Iwakiri, Wataru; Yamada, Shin'ya; Tamagawa, Toru; Mihara, Tatehiro; Nagase, Fumiaki


    Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4- 100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered a stable and intrinsic spectral feature in Her X-1. The broad hump lacked a sharp structure like an absorption edge. Thus it was represented by two different spectral models: an ionized partial covering or an additional broad line at 6.5 keV. The former required a persistently existing ionized absorber, whose origin was unclear. In the latter case, the Gaussian fitting of the 6.5-keV line needs a large width of sigma = 1.0-1.5 keV and a large equivalent width of 400-900 eV. If the broad line originates from Fe fluorescence of accreting matter, its large width may be explained by the Doppler broadening in the accretion flow. However, the large equivalent width may be inconsistent with a simple accretion geometry.

  8. Compression of 1030-nm femtosecond pulses after nonlinear spectral broadening in Corning® HI 1060 fiber: Theory and experiment

    Directory of Open Access Journals (Sweden)

    Michael E. Reilly


    Full Text Available We present the design and implementation of femtosecond pulse compression at 1030 nm based on spectral broadening in single-mode fiber, followed by dispersion compensation using an optimized double-pass SF11 prism pair. The source laser produced 1030-nm 144-fs pulses which were coupled into Corning® HI 1060 fiber, whose length was chosen to be 40 cm by using a pulse propagation model based on solving the generalized nonlinear Schrödinger equation. A maximum broadening to 60-nm bandwidth was obtained, following which compression to 60 ± 3 fs duration was achieved by using a prism-pair separation of 1025 ± 5 mm.

  9. Characterization of ion-irradiated ODS Fe–Cr alloys by doppler broadening spectroscopy using a positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Parente, P.; Leguey, T. [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Castro, V. de, E-mail: [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain); Gigl, T.; Reiner, M.; Hugenschmidt, C. [FRM II and Physics Department, Technische Universität München, 85747 Garching (Germany); Pareja, R. [Departamento de Física and IAAB, Universidad Carlos III de Madrid, 28911 Leganés (Spain)


    The damage profile of oxide dispersion strengthened steels after single-, or simultaneous triple-ion irradiation at different conditions has been characterized using a low energy positron beam in order to provide information on microstructural changes induced by irradiation. Doppler broadening and coincident Doppler broadening measurements of the positron annihilation line have been performed on different Fe–Cr–(W,Ti) alloys reinforced with Y{sub 2}O{sub 3}, to identify the nature and stability of irradiation-induced open-volume defects and their possible association with the oxide nanoparticles. It was found that irradiation induced vacancy clusters are associated with Cr atoms. The results are of highest interest for modeling the damage induced by 14 MeV neutrons in reduced activation Fe–Cr alloys relevant for fusion devices.

  10. The effects of relativistic broadening and frequency down-shift on electron-cyclotron emission measurements in EAST

    Institute of Scientific and Technical Information of China (English)

    Liu Yong; Han Xiang; Ti Ang; Wang Yu-Min; Ling Bi-Li; Hu Li-Qun; Gao Xiang


    This paper presents a theoretical calculation of the effects of relativistic broadening and frequency down-shift on the electron cyclotron emission measurements for a wide range of plasma parameters in the Experimental Advanced Superconducting Tokamak (EAST).The calculation is based on the radiation transfer equation,with the reabsorption and reemission processes taken into account.The broadening effect contributes to the radial resolution of the measurement,and the calculation results indicate that it is ~ 2 cm in the case of the central electron temperature 10 keV.A pseudo radial displacement of the obtained electron temperature profile occurs if the relativistic frequency down-shift effect is not taken into account in the determination of the emission layer position.The shift could be a few centimeters as the electron temperature increases,and this effect should be taken into account.

  11. Detection of helium in irradiated Fe9Cr alloys by coincidence Doppler broadening of slow positron annihilation (United States)

    Cao, Xingzhong; Zhu, Te; Jin, Shuoxue; Kuang, Peng; Zhang, Peng; Lu, Eryang; Gong, Yihao; Guo, Liping; Wang, Baoyi


    An element analysis method, coincidence Doppler broadening spectroscopy of slow positron annihilation, was employed to detect helium in ion-irradiated Fe9Cr alloys. Spectra with higher peak to background ratio were recorded using a two-HPGe detector coincidence measuring system. It means that information in the high-momentum area of the spectra can be used to identify helium in metals. This identification is not entirely dependent on the helium concentration in the specimens, but is related to the structure and microscopic arrangement of atoms surrounding the positron annihilation site. The results of Doppler broadening spectroscopy and transmission electron microscopy show that vacancies and dislocations were formed in ion-irradiated specimens. Thermal helium desorption spectrometry was performed to obtain the types of He traps.

  12. Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region

    KAUST Repository

    Khan, Mohammed Zahed Mustafa


    The effect of the active region inhomogeneity on the spectral characteristics of InAs/InP quantum-dash (Qdash) lasers is examined theoretically by solving the coupled set of carrier-photon rate equations. The inhomogeneity due to dash size or composition fluctuation is included in the model by considering dispersive energy states and characterized by a Gaussian envelope. In addition, the technique incorporates multilongitudinal photon modes and homogeneous broadening of the optical gain. The results predict a red shift in the central lasing wavelength of Qdash lasers on increasing the inhomogeneous broadening either explicitly or implicitly, which supports various experimental observations. The threshold current density and the lasing bandwidth are also found to increase. © 2012 IEEE.

  13. Determination of foreign broadening coefficients for Methane Lines Targeted by the Tunable Laser Spectrometer (TLS) on the Mars Curiosity Rover (United States)

    Manne, Jagadeeshwari; Bui, Thinh Q.; Webster, Christopher R.


    Molecular line parameters of foreign- broadening by air, carbon dioxide, and helium gas have been experimentally determined for infrared ro-vibrational spectral lines of methane isotopologues (12CH4 and 13CH4) at 3057 cm-1 targeted by the Tunable Laser Spectrometer (TLS) in the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity rover. From multi-spectrum analyses with the speed-dependent Voigt line profile with Rosenkrantz line-mixing, speed-dependence and line-mixing effects were quantified for methane spectra at total pressures up to 200 mbar. The fitted air-broadening coefficients deviated from 8-25% to those reported in the HITRAN-2012 database.

  14. [Gastric band erosion: Alternative management]. (United States)

    Echaverry-Navarrete, Denis José; Maldonado-Vázquez, Angélica; Cortes-Romano, Pablo; Cabrera-Jardines, Ricardo; Mondragón-Pinzón, Erwin Eduardo; Castillo-González, Federico Armando


    Obesity is a public health problem, for which the prevalence has increased worldwide at an alarming rate, affecting 1.7 billion people in the world. To describe the technique employed in incomplete penetration of gastric band where endoscopic management and/or primary closure is not feasible. Laparoscopic removal of gastric band was performed in five patients with incomplete penetrance using Foley catheterization in the perforation site that could lead to the development of a gastro-cutaneous fistula. The cases presented include a leak that required surgical lavage with satisfactory outcome, and one patient developed stenosis 3 years after surgical management, which was resolved endoscopically. In all cases, the penetration site closed spontaneously. Gastric band erosion has been reported in 3.4% of cases. The reason for inserting a catheter is to create a controlled gastro-cutaneous fistula, allowing spontaneous closure. Various techniques have been described: the totally endoscopic, hybrid techniques (endoscopic/laparoscopic) and completely laparoscopic. A technique is described here that is useful and successful in cases where the above-described treatments are not viable. Copyright © 2015. Published by Masson Doyma México S.A.

  15. S-Band propagation measurements (United States)

    Briskman, Robert D.


    A geosynchronous satellite system capable of providing many channels of digital audio radio service (DARS) to mobile platforms within the contiguous United States using S-band radio frequencies is being implemented. The system is designed uniquely to mitigate both multipath fading and outages from physical blockage in the transmission path by use of satellite spatial diversity in combination with radio frequency and time diversity. The system also employs a satellite orbital geometry wherein all mobile platforms in the contiguous United States have elevation angles greater than 20 deg to both of the diversity satellites. Since implementation of the satellite system will require three years, an emulation has been performed using terrestrial facilities in order to allow evaluation of DARS capabilities in advance of satellite system operations. The major objective of the emulation was to prove the feasibility of broadcasting from satellites 30 channels of CD quality programming using S-band frequencies to an automobile equipped with a small disk antenna and to obtain quantitative performance data on S-band propagation in a satellite spatial diversity system.

  16. Roles of blocking layer and anode bias in processes of impurity-band transition and transport for GaAs-based blocked-impurity-band detectors (United States)

    Wang, Xiaodong; Wang, Bingbing; Chen, Xiaoyao; Chen, Yulu; Hou, Liwei; Xie, Wei; Pan, Ming


    Recently, GaAs-based BIB detector has attracted a lot of attention in the area of THz photovoltaic detection due to potential application values in security check and drug inspection. However, the physical mechanisms involving in carrier transition and transport are still unclear due to the poor material quality and immature processing technique. In this paper, the dark current and THz response characteristics have thus been numerically studied for GaAs-based blocked-impurity-band (BIB) detectors. The key parameters and physical models are constructed by simultaneously considering carrier freeze-out and impurity-band broadening effects. Roles of blocking layer and anode bias in processes of impurity-band transition and transport are intensively investigated, and the results can be well explained by numerical models. It is demonstrated that the effective electric field for the detector is only located in the absorbing layer, and can determine to a large extent the magnitude of the dark current and THz response. While the blocking layer not only can suppress dark current but also can attenuate responsivity due to its electric-field modulation effect.

  17. Variations in onset of action potential broadening: effects on calcium current studied in chick ciliary ganglion neurones. (United States)

    Pattillo, J M; Artim, D E; Simples, J E; Meriney, S D


    1. The voltage dependence and kinetic properties of stage 40 ciliary ganglion calcium currents were determined using short (10 ms) voltage steps. These properties aided the interpretation of the action potential-evoked calcium current described below, and the comparison of our data with those observed in other preparations. 2. Three different natural action potential waveforms were modelled by a series of ramps to generate voltage clamp commands. Calcium currents evoked by these model action potentials were compared before and after alterations in the repolarization phase of each action potential. 3. Abrupt step repolarizations from various time points were used to estimate the time course of calcium current activation during each action potential. Calcium current evoked by fast action potentials (duration at half-amplitude, 0.5 or 1.0 ms) did not reach maximal activation until the action potential had repolarized by 40-50 %. In contrast, calcium current evoked by a slow action potential (duration at half-amplitude, 2.2 ms) was maximally activated near the peak of the action potential. 4. Slowing the rate of repolarization of the action potential (broadening) from different times was used to examine effects on peak and total calcium influx. With all three waveforms tested, broadening consistently increased total calcium influx (integral). However, peak calcium current was either increased or decreased depending on the duration of the control action potential tested and the specific timing of the initiation of broadening the repolarization phase. 5. The opposite effects on peak calcium current observed with action potential broadening beginning at different time points in repolarization may provide a mechanism for the variable effects of potassium channel blockers on transmitter release magnitude.

  18. Collisional Broadening and Shift of D1 and D2 Spectral Lines in Atomic Alkali Vapor - Noble Gas Systems (United States)


    broadening using a WKB approximation in a semiclassical approach (Weisskopf, 1932a, 1932b), and Jabloński, who also used a WKB approximation but treated...appropriate, compiled and executed on AFIT’s Linux Cluster and on supercomputers run by the DoD High Performance Computing Modernization Program...The result is a cross section that decays with increasing temperature; we expect that a greater kinetic energy results in a lesser fractional change

  19. Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber


    Andreas Hoffmann; Michael Zürch; Christian Spielmann


    In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF6) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yie...

  20. Influence of Electron–Acoustic-Phonon Scattering on Intensity Power Broadening in a Coherently Driven Quantum-Dot–Cavity System

    Directory of Open Access Journals (Sweden)

    C. Roy


    Full Text Available We present a quantum optics formalism to study the intensity power broadening of a semiconductor quantum dot interacting with an acoustic-phonon bath and a high-Q microcavity. Power broadening is investigated using a time-convolutionless master equation in the polaron frame, which allows for a nonperturbative treatment of the interaction of the quantum dot with the phonon reservoir. We calculate the full non-Lorentzian photoluminescence (PL line shapes and numerically extract the intensity linewidths of the quantum-dot exciton and the cavity mode as a function of the pump rate and temperature. For increasing field strengths, multiphonon and multiphoton effects are found to be important, even for phonon-bath temperatures as low as 4 K. We show that the interaction of the quantum dot with the phonon reservoir introduces pronounced features in the power-broadened PL line shape, enabling one to observe clear signatures of electron-phonon scattering. The PL line shapes from cavity pumping and exciton pumping are found to be distinctly different, primarily since the latter is excited through the exciton-phonon reservoir. To help explain the underlying physics of phonon scattering on the power-broadened line shape, an effective phonon Lindblad master equation derived from the full time-convolutionless master equation is introduced; we identify and calculate distinct Lindblad scattering contributions from electron-phonon interactions, including effects such as excitation-induced dephasing, incoherent exciton excitation, and exciton-cavity feeding. Our effective phonon master equation is shown to reproduce the full PL intensity and the phonon-coupling effects very well, suggesting that its general Lindblad form may find widespread use in semiconductor cavity-QED.

  1. Color-Tunable Mirrors Based on Electrically Regulated Bandwidth Broadening in Polymer-Stabilized Cholesteric Liquid Crystals (Postprint) (United States)


    September 2014 4. TITLE AND SUBTITLE COLOR -TUNABLE MIRRORS BASED ON ELECTRICALLY REGULATED BANDWIDTH BROADENING IN POLYMER- STABILIZED CHOLESTERIC...Approved for public release; distribution unlimited. This report contains color . 13. SUPPLEMENTARY NOTES PA Case Number: 88ABW-2014-1978, 14. ABSTRACT We report on the preparation of color -tunable mirrors based on electrically regulated bandwidth

  2. Pulse-driven non-linear Alfvén waves and their role in the spectral line broadening (United States)

    Chmielewski, P.; Srivastava, A. K.; Murawski, K.; Musielak, Z. E.


    We study the impulsively generated non-linear Alfvén waves in the solar atmosphere and describe their most likely role in the observed non-thermal broadening of some spectral lines in solar coronal holes. We solve numerically the time-dependent magnetohydrodynamic equations to find temporal signatures of large-amplitude Alfvén waves in the solar atmosphere model of open and expanding magnetic field configuration, with a realistic temperature distribution. We calculate the temporally and spatially averaged, instantaneous transversal velocity of non-linear Alfvén waves at different heights of the model atmosphere and estimate its contribution to the unresolved non-thermal motions caused by the waves. We find that the pulse-driven non-linear Alfvén waves with the amplitude Av = 50 km s- 1 are the most likely candidates for the non-thermal broadening of Si viii λ1445.75 Å line profiles in the polar coronal hole as reported by Banerjee et al. We also demonstrate that the Alfvén waves driven by comparatively smaller velocity pulse with amplitude Av = 25 km s- 1 may contribute to the spectral line width of the same line at various heights in coronal hole broadening. We conclude that the non-linear Alfvén waves excited impulsively in the lower solar atmosphere may be responsible for the observed spectral line broadening in polar coronal holes. This is an important result as it allows us to conclude that such large amplitude and pulse-driven Alfvén waves may indeed exist in solar coronal holes. The existence of these waves may impart the required momentum to accelerate the solar wind.

  3. Coherence-controlled transparency and far-from-degenerate parametric gain in a strongly-absorbing Doppler-broadened medium

    CERN Document Server

    George, T F; George, Thomas F.


    An inversionless gain of anti-Stokes radiation above the oscillation threshold in an optically-dense far-from-degenerate double-Lambda Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes are illustrated with numerical simulations applied to sodium dimer vapor. Optical switching from absorption to gain via transparency controlled by a small variation of the medium and of the driving radiation parameters which are at a level less than one photon per molecule is shown.

  4. Theoretical Calculations of Thermal Broadenings and Transition Probabilities of R, R' and B Line-Groups for Ruby

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; LIU Yan-Yun; CHEN Ju-Rong


    On the basis of the unified calculation of the thermal shifts of R1 line, R2 line and ground-state-splitting transition probabilities of direct and Raman processes have theoretically been calculated. The thermal broadenings of R,The theoretically predicted transition probabilities are in good agreement with the experimental ones.PACS numbers: 71.70.Ch, 78.20.Nv, 63.20.Mt, 63.20.Kr

  5. Ultrawideband coherent noise lidar range-Doppler imaging and signal processing by use of spatial-spectral holography in inhomogeneously broadened absorbers. (United States)

    Li, Youzhi; Hoskins, Alan; Schlottau, Friso; Wagner, Kelvin H; Embry, Carl; Babbitt, William Randall


    We introduce a new approach to coherent lidar range-Doppler sensing by utilizing random-noise illuminating waveforms and a quantum-optical, parallel sensor based on spatial-spectral holography (SSH) in a cryogenically cooled inhomogeneously broadened absorber (IBA) crystal. Interference between a reference signal and the lidar return in the spectrally selective absorption band of the IBA is used to sense the lidar returns and perform the front-end range-correlation signal processing. Modulating the reference by an array of Doppler compensating frequency shifts enables multichannel Doppler filtering. This SSH sensor performs much of the postdetection signal processing, increases the lidar system sensitivity through range-correlation gain before detection, and is capable of not only Doppler processing but also parallel multibeam reception using the high-spatial resolution of the IBA crystals. This approach permits the use of ultrawideband, high-power, random-noise, cw lasers as ranging waveforms in lidar systems instead of highly stabilized, injection-seeded, and amplified pulsed or modulated laser sources as required by most conventional coherent lidar systems. The capabilities of the IBA media for many tens of gigahertz bandwidth and resolution in the 30-300 kHz regime, while using either a pseudo-noise-coded waveform or just a high-power, noisy laser with a broad linewidth (e.g., a truly random noise lidar) may enable a new generation of improved lidar sensors and processors. Preliminary experimental demonstrations of lidar ranging and simulation on range-Doppler processing are presented.

  6. Increased spike broadening and slow afterhyperpolarization in CA1 pyramidal cells of streptozotocin-induced diabetic rats. (United States)

    Kamal, A; Artola, A; Biessels, G J; Gispen, W H; Ramakers, G M J


    Diabetes mellitus is associated with impairments of cognitive function both in humans and animal models. In diabetic rats cognitive deficits are related to alterations in activity-dependent synaptic plasticity in the hippocampus. Many similarities with the pathophysiology of normal brain aging have been noted, and the view emerges that the effects of diabetes on the brain are best described as "accelerated brain aging."In the present study we examined whether CA1 pyramidal neurons from streptozotocin-induced diabetic rats display an increased slow afterhyperpolarization, often considered as a hallmark of neuronal aging. We found no differences in resting membrane potential, input resistance, membrane time-constant, and action potential amplitude and duration between CA1 pyramidal neurons from streptozotocin-induced diabetic and age-matched control rats. During a train of action potentials, however, there is an increased broadening of the action potentials in diabetic animals, so-called "spike broadening." The amplitude of the slow afterhyperpolarization elicited by a train of action potentials is indeed increased in diabetic animals. Interestingly, when the slow afterhyperpolarization is elicited by a Ca(2+) spike, there is no difference between control and diabetic rats. This indicates that the increased slow afterhyperpolarization in diabetes is likely to be due to an increased Ca(2+) influx resulting from the increased spike broadening. These data underscore the notion that the diabetic brain at the neuronal level shares properties with brain aging.

  7. A Simple Analytical Approximation to an Inhomogeneously-Broadened Dispersion Spectrum. Application to Absorption-Dispersion Admixtures. (United States)

    Bales, Barney L


    A simple analytical approximation to an inhomogeneously-broadened dispersion signal is proposed and tested with resonance lines broadened by unresolved hyperfine structure. Spectral parameters may be rapidly and accurately extracted using a nonlinear least-squares fitting algorithm. Combining the new approximation to a dispersion signal with a well-known approximation to the absorption signal allows dispersion-absorption admixtures, a problem of growing importance, to be analyzed quickly and accurately. For pure dispersion signals, the maximum difference between the fit and the signal for unresolved lines is 1.1 % of the maximum intensity. For pure absorption, the difference is 0.33 % of the peak-to-peak intensity, and for admixtures up to 40 % dispersion (maximum intensity/peak-to-peak intensity), the difference is 0.7 %. The accuracy of the recovered spectral parameters depends on the degree of inhomogeneously-broadened and the percentage admixture, but they are generally about 1 % at most. A significant finding of the work is that the parameters pertinent to the dispersion or the absorption are insignificantly different when fitting isolated lines vs. fitting admixtures. Admixtures with added noise or an unsuspected extraneous line are investigated.

  8. Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

    Energy Technology Data Exchange (ETDEWEB)

    Weichert, Stefan


    The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

  9. A comparison between different X-ray diffraction line broadening analysis methods for nanocrystalline ball-milled FCC powders

    Energy Technology Data Exchange (ETDEWEB)

    Soleimanian, V. [Shahrekord University, Department of Physics, Faculty of Sciences, P.O. Box 115, Shahrekord (Iran, Islamic Republic of); Shahrekord University, Nanotechnology Research Center, Shahrekord (Iran, Islamic Republic of); Mojtahedi, M. [Pooya Gharb Branch of University of Applied Science and Technology, Department of Materials Engineering, Kermanshah (Iran, Islamic Republic of)


    The microstructural characteristics of aluminum, copper and nickel powders are investigated using different X-ray diffraction line broadening analysis approaches. Prior to analysis, the powders were ball-milled to produce a nanocrystalline structure with high density of probable types of lattice defects. A variety of methods, including Scherrer, Williamson-Smallman, Williamson-Hall, Warren-Averbach, modified Williamson-Hall, modified Warren-Averbach, Rietveld refinement and whole powder pattern modeling (WPPM) approaches are applied. In this way, microstructural characteristics such as crystallite size, microstrain, dislocation density, effective outer cut-off radius of dislocations and the probability of twining and stacking faults are calculated. On the other hand, the results of conventional and advanced line broadening analysis methods are compared. It is revealed that the density of linear and planar defects in the mechanically deformed aluminum powder is significantly smaller than that of copper and nickel, as well as the level of anisotropic strain broadening. Moreover, the WPPM procedure provided a better profile fitting with more accurate results. (orig.)

  10. The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars

    CERN Document Server

    Simón-Díaz, S; Castro, N; Herrero, A; Aerts, C; Puls, J; Telting, J; Grassitelli, L


    We aim to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars to evaluate its physical origin. We use high-resolution spectra of ~430 stars with spectral types in the range O4-B9 (all luminosity classes). We characterize the line-broadening of adequate diagnostic metal lines using a combined FT and GOF technique. We perform a quantitative spectroscopic analysis of the whole sample using automatic tools coupled with a huge grid of FASTWIND models. We also incorporate quantitative information about line asymmetries to our observational description of the characteristics of the line-profiles, and present a comparison of the shape and type of line-profile variability found in a small sample of O stars and B supergiants with still undefined pulsational properties and B main sequence stars with variable line-profiles. We present a homogeneous and statistically significant overview of the (single snapshot) line-broadening properties of stars in the whole O and B star doma...

  11. An extension to flat band ferromagnetism (United States)

    Gulacsi, M.; Kovacs, G.; Gulacsi, Z.


    From flat band ferromagnetism, we learned that the lowest energy half-filled flat band gives always ferromagnetism if the localized Wannier states on the flat band satisfy the connectivity condition. If the connectivity conditions are not satisfied, ferromagnetism does not appear. We show that this is not always the case namely, we show that ferromagnetism due to flat bands can appear even if the connectivity condition does not hold due to a peculiar behavior of the band situated just above the flat band.

  12. Implementation and Investigation of a Compact Circular Wide Slot UWB Antenna with Dual Notched Band Characteristics using Stepped Impedance Resonators

    Directory of Open Access Journals (Sweden)

    Yingsong Li


    Full Text Available A coplanar waveguide (CPW fed ultra-wideband (UWB antenna with dual notched band characteristics is presented in this paper. The circular wide slot and circular radiation patch are utilized to broaden the impedance bandwidth of the UWB antenna. The dual notched band functions are achieved by employing two stepped impedance resonators (SIRs which etched on the circular radiation patch and CPW excitation line, respectively. The two notched bands can be controlled by adjusting the dimensions of the two stepped impedance resonators which give tunable notched band functions. The proposed dual notched band UWB antenna has been designed in details and optimized by means of HFSS. Experimental and numerical results show that the proposed antenna with compact size of 32 × 24 mm2, has an impedance bandwidth range from 2.8 GHz to 13.5 Hz for voltage standing-wave ratio (VSWR less than 2, except the notch bands 5.0 GHz - 6.2 GHz for HIPERLAN/2 and IEEE 802.11a (5.1 GHz - 5.9 GHz and 8.0 GHz - 9.3 GHz for satellite and military applications.

  13. Uniaxial stress influence on lattice, band gap and optical properties of n-type ZnO:first-principles calculations

    Institute of Scientific and Technical Information of China (English)

    Yang Ping; Li Pei; Zhang Li-Qiang; Wang Xiao-Liang; Wang Huan; Song Xi-Fu; Xie Fang-Wei


    The lattice,the band gap and the optical properties of n-type ZnO under uniaxial stress are investigated by firstprinciples calculations.The results show that the lattice constants change linearly with stress.Band gaps are broadened linearly as the uniaxial compressive stress increases.The change of band gap for n-type ZnO comes mainly from the contribution of stress in the c-axis direction,and the reason for band gap of n-type ZnO changing with stress is also explained.The calculated results of optical properties reveal that the imaginary part of the dielectric function decreases with the increase of uniaxial compressive stress at low energy.However,when the energy is higher than 4.0 eV,the imaginary part of the dielectric function increases with the increase of stress and a blueshift appears.There are two peaks in the absorption spectrum in an energy range of 4.0-13.0 eV.The stress coefficient of the band gap of n-type ZnO is larger than that of pure ZnO,which supplies the theoretical reference value for the modulation of the band gap of doped ZnO.

  14. Study of band gap and determination of size of PbS quantum dots synthesized by colloidal solution

    Directory of Open Access Journals (Sweden)

    M. S. Ghamsari


    Full Text Available   PbS semiconductor non-crystals have been synthesized in order to study the modification of their electronic structures and optical properties in relation to their size. The synthesis has been carried out by using the techniques of colloidal chemistry. Strong quantum confinement behavior has been observed based on the analysis of optical spectra of these particles. The average particle size approximated by x-ray line width and hyperbolic band model calculation. Heterogeneous broadening of optical spectrum is studied finally.

  15. Positron states in polyethylene and polytetrafluoroethylene: A positron lifetime and Doppler-broadening study (United States)

    Dlubek, G.; Saarinen, K.; Fretwell, H. M.


    Simultaneous positron lifetime (LT) and Doppler-broadening (DB) measurements on semi-crystalline polyethylene (PE) and polytetrafluoroethylene (PTFE) polymers have been performed in the temperature range 80-300 K. The LT spectra are analysed assuming four exponential components. Two long-lived components are found and are attributed to ortho-positroniums (o-Ps) pick-off annihilation in crystalline regions ( τ3=0.9-1.2 ns), and in free-volume holes in the amorphous phase ( τ4=1.5-2.8 (PE); τ4=2.5-4.4 ns (PTFE)). The values of τ4 obtained correspond to an increase of the mean hole size from 0.053 (at 80 K) to 0.188 nm 3 (at 300 K) in PE, and from 0.152 to 0.372 nm 3 in PTFE. The DB curves were fitted with a sum of three Gaussians, the narrowest of which is assumed to represent self-annihilation of para-positroniums (p-Ps) localised at holes. The intensity of the narrow component, In, varies between 0% and 5% in a similar way to the LT intensity I4. From this and from the intensity ratio of the LT spectra, 3 I1/( I3 + I4) ≈ 1, we conclude that pick off is the only important Ps quenching reaction. Therefore, the variation in the LT and DB intensities is attributed exclusively to inhibition or anti-inhibition of Ps formation. The intensity ratio of the narrow DB component 3 In/ I4=0.55 to 0.9 is smaller than the anticipated value of 1. Possible reasons of this effect will be discussed. It is shown that the average positron lifetime is dominated by the o-Ps component, while the behaviour of the DB peak height is mainly affected by p-Ps annihilation. Further, the results of the four-component decomposition of LT spectra were compared with those obtained from a three-component analysis, and from the comparison it was concluded that a three-component analysis of the o-Ps lifetime in semi-crystalline polymers, has some, albeit limited, physical relevance.

  16. Capitalizing on Education and Outreach (E/O) Expertise to Broaden Impacts (Invited) (United States)

    Girguis, P. R.; Herren, C.; Decharon, A.


    Academic scientists have a number of avenues through which they can participate in education and outreach (E/O) programs to address the mandate for broader impacts. As a principal investigator (PI) at an R1 institution, I (Girguis) have both developed and participated in a variety of E/O programs that span the spectrum from ad hoc groups (e.g. informal high school internships in my laboratory) to regional efforts (e.g. Harvard’s Microbial Science Initiative) and national organizations (e.g. RIDGE 2000; Centers for Ocean Sciences Education Excellence, COSEE). Each of these E/O efforts required varying degrees of preparation and participation by my laboratory members (e.g. graduate students and postdoctoral researchers) and I, and yielded different outcomes and products. Ad hoc programs typically require a higher degree of effort on the part of the PI and have a high, though local, impact on the audience. These programs can be personally rewarding for the PI, who likely has played a major role in developing the program. In contrast, working with regional and national groups requires PIs to understand the nature of each program to successfully integrate within the existing structure. The net time and effort invested by scientists in larger-scale E/O efforts may be equal to that of ad hoc programs. However, interaction with high-quality program facilitators ensures that the outcomes are grounded in best educational practices and that outputs are educator-vetted, well maintained (online or through publications), and broadly disseminated. In addition, program facilitators also collect and analyze evaluation data to provide constructive feedback to PIs, enabling the latter to refine their presentation styles and content levels to improve future E/O efforts. Thus involvement with larger programs can effectively broaden one’s impact. During this presentation, we will present one scientist’s perspective on the advantages and limitations of these different modes of E

  17. IBP's Four-Prong Approach for Broadening Participation in the STEM Community (United States)

    Ricciardi, L.; Fauver, A.; Johnson, A.; Detrick, L.; Siegfried, D.; Thomas, S.; Valaitis, S.


    The goal of the Institute for Broadening Participation (IBP) is to increase diversity in the Science, Technology, Engineering and Mathematics (STEM) workforce. As a freestanding non-profit dedicated to this work IBP is uniquely positioned to provide resources to faculty and students that individual institutions and disciplinary based programs cannot. Through its initial work with the NSF Integrative Graduate Education and Research Traineeship (IGERT), Research Experiences for Undergraduates (REU), and Alliance for Graduate Education and the Professoriate (AGEP) programs, IBP developed a four-pronged approach open to all members of the STEM community nationally for addressing the problem of underrepresentation: Synthesizing information - compiling and translating best practices into materials and resources accessible and useful to a broad national audience; Creating and maintaining strategic web resources - making information on programs, best practices, and references easily available to a wide audience including students, faculty, and administrators; Extensive face-to-face and virtual outreach - drawing constituents to the resources available via IBP that support students and faculty through the entire STEM pathway; and Catalyzing partnerships - cultivating a community of practice and culture of diversity, to reduce isolation among diversity practitioners, and to increase information sharing. IBP is also home to several successful initiatives that use both virtual and face-to-face components to bring together underrepresented students with established underrepresented and other scientists in academia, government and industry. These connections provide underrepresented students with supportive mentoring, networking opportunities, and professional skill development contributing to an overall improved retention rate of underrepresented students majoring in STEM degrees. IBP's initiatives include the NASA One Stop Shopping Initiative (NASA OSSI), Pathways to Ocean

  18. The DSS-14 C-band exciter (United States)

    Rowan, D. R.


    The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

  19. Relativistic Model for two-band Superconductivity


    Ohsaku, Tadafumi


    To understand the superconductivity in MgB2, several two-band models of superconductivity were proposed. In this paper, by using the relativistic fermion model, we clearize the effect of the lower band in the superconductivity.

  20. Bonds and bands in semiconductors

    CERN Document Server

    Phillips, Jim


    This classic work on the basic chemistry and solid state physics of semiconducting materials is now updated and improved with new chapters on crystalline and amorphous semiconductors. Written by two of the world's pioneering materials scientists in the development of semiconductors, this work offers in a single-volume an authoritative treatment for the learning and understanding of what makes perhaps the world's most important engineered materials actually work. Readers will find: --' The essential principles of chemical bonding, electron energy bands and their relationship to conductive and s