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Sample records for lddp proposes broadening

  1. 77 FR 2031 - Proposed Information Collection; Comment Request; Market Research To Broaden and Deepen U.S...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-13

    ...) have formed a project team to conduct market segmentation research and analysis. The market segmentation is a systematic approach for identifying clusters of companies with similar needs and behavior... International Trade Administration Proposed Information Collection; Comment Request; Market Research To Broaden...

  2. Broadening Transfer Opportunities

    ERIC Educational Resources Information Center

    Dearing, Bruce

    1975-01-01

    Broadened opportunity for transfer offers a potential for bolstering sagging enrollments, and increases capacities for accomodating the educational needs of a broader spectrum of a democratic society. (Author/KE)

  3. Broadening the Recruiting Market.

    ERIC Educational Resources Information Center

    Central All-Volunteer Force Task Force, Washington, DC.

    The purpose of the study is to broaden the enlisted recruiting market, especially for high school graduates and describe measures to complete or expedite actions initiated by ASD (M and RA) (Assistant Secretary of Defense Manpower and Reserve Affairs) and the military services and to take additional actions to enhance recruiting. (Author)

  4. Broadening the Recruiting Market.

    ERIC Educational Resources Information Center

    Central All-Volunteer Force Task Force, Washington, DC.

    The purpose of the study is to broaden the enlisted recruiting market, especially for high school graduates and describe measures to complete or expedite actions initiated by ASD (M and RA) (Assistant Secretary of Defense Manpower and Reserve Affairs) and the military services and to take additional actions to enhance recruiting. (Author)

  5. Broadening, Deepening, and Consolidating

    ERIC Educational Resources Information Center

    Cumming, Alister

    2004-01-01

    I encourage the editors of and contributors to "Language Assessment Quarterly" to continue, and to extend, three directions that are integral to the development of the field of language assessment: (a) to broaden the scope of inquiry and contexts that inform knowledge about language assessment; (b) to deepen the theoretical premises and…

  6. Neutrino Induced Doppler Broadening

    PubMed Central

    Jolie, J.; Stritt, N.

    2000-01-01

    When a nucleus undergoes beta decay via the electron capture reaction, it emits an electron neutrino. The neutrino emission gives a small recoil to the atom, which can be experimentally observed as a Doppler broadening on subsequently emitted gamma rays. Using the two-axis flat-crystal spectrometer GAMS4 and the electron capture reaction in 152Eu, the motion of atoms having an excess kinetic energy of 3 eV in the solid state was studied. It is shown how the motion of the atom during the first hundreds of femtoseconds can be reconstructed. The relevance of this knowledge for a new neutrino helicity experiment is discussed. PMID:27551591

  7. Does interest broaden or narrow attentional scope?

    PubMed

    Sung, Billy; Yih, Jennifer

    2015-08-10

    Theory proposes that interest is a positive emotion that may either broaden attention to facilitate processing of new information, or narrow attention to preserve engagement with new information. To our knowledge, no research has directly examined the effect of interest on attentional scope. Across four experiments, we show that traits associated with the propensity to experience interest-specifically, trait curiosity and internal boredom proneness-are associated with a narrower scope of attention. We also find that, instead of broadening, interest actually narrows attentional scope in comparison to a neutral state and awe. Challenging the conventional notion that all positive emotions broaden cognition and attention, our findings suggest that specific emotions influence attention in ways that extend beyond a general emotional valence effect.

  8. Broadening nanotechnology's impact on development

    NASA Astrophysics Data System (ADS)

    Beumer, Koen

    2016-05-01

    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.

  9. Broadening the Earthscan Industry

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Law Environmental, Inc. is a professional engineering and Earth sciences consulting firm. When a client, who operates an electricity generating plant required assistance in evaluating the effects of a heated water discharge on aquatic life, Law proposed a Visiting Investigator Program (VIP) to Stennis Space Center (SSC). The VIP is directed toward small companies who could use remote sensing profitably, but do not have the money to explore new technologies. SSC provided remote sensing data to Law enabling it to produce images of the thermal "plume," the water area affected by the discharge. After comparisons of plant and animal life with similar life in an unaffected control area, Law concluded that the discharge effect was not significant.

  10. Medical vest broadens treatment capability

    NASA Technical Reports Server (NTRS)

    Johnson, G. S.

    1970-01-01

    Universal sized vest, with specially tailored pockets designed to hold medical supplies, provides first aid/first care medical teams with broadened on-site capability. Vest is made of nylon, tough fibrous materials, and polyvinyl chloride. Design facilitates rapid donning, doffing, and adjustment.

  11. Level broadening and quantum interference effects in insulators

    NASA Astrophysics Data System (ADS)

    Medina, Ernesto; Pastawski, Horacio

    2000-03-01

    We study quantum interference effects in the context of the Nguyen-Spivak-Shklovskii (NSS) model including level broadening due to inelastic events. Improving on a recent mean-field approach, we incorporate path correlations and study both the log-conductance and its fluctuations. In contrast with mean field, we find that all changes in the conductance, due to broadening, imply corrections to the localization length. Furthermore, the change in the magnetoconductance sign, predicted by mean field, is not borne out by direct solution of the NSS model within reasonable broadening parameters. We compute a phase diagram for the magnetoconductance in the broadening parameter space and propose a replica theory for weak inelastic events.

  12. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  13. Multigroup Free-atom Doppler-broadening Approximation. Experiment

    SciTech Connect

    Gray, Mark Girard

    2015-11-06

    The multigroup energy Doppler-broadening approximation agrees with continuous energy Dopplerbroadening generally to within ten percent for the total cross sections of 1H, 56Fe, and 235U at 250 lanl. Although this is probably not good enough for broadening from room temperature through the entire temperature range in production use, it is better than any interpolation scheme between temperatures proposed to date, and may be good enough for extrapolation from high temperatures. The method deserves further study since additional improvements are possible.

  14. Bandwidth broadening for stripline circulator

    NASA Astrophysics Data System (ADS)

    Chao, Hsien-Wen; Wu, Shi-Yao; Chang, Tsun-Hsu

    2017-02-01

    This work provides a detailed analysis and simulation to demonstrate how to broaden the operating bandwidth of a circulator. A double-Y junction circulator is designed, and the shape of the central stripline is optimized with the knowledge of a modified equation. The equation predicts two resonant conditions. The overlapping of the two resonant conditions jointly constitutes the broad bandwidth. The bias magnetic field is simulated and then used in full electromagnetic-wave simulation. The designed circulator was fabricated in the S-band for communication purpose. The measured results agree very well with simulation. The overall operation range is from 1643 to 2027 MHz with the insertion loss less than 0.35 dB, reflection, and isolation better than 20 dB. The mechanism will be discussed.

  15. Adaptive broadening to improve spectral resolution in the numerical renormalization group

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Sup B.; Weichselbaum, Andreas

    2016-12-01

    We propose an adaptive scheme of broadening the discrete spectral data from numerical renormalization group (NRG) calculations to improve the resolution of dynamical properties at finite energies. While the conventional scheme overbroadens narrow features at large frequency by broadening discrete weights with constant width in log-frequency, our scheme broadens each discrete contribution individually based on its sensitivity to a z -shift in the logarithmic discretization intervals. We demonstrate that the adaptive broadening better resolves various features in noninteracting and interacting models at comparable computational cost. The resolution enhancement is more significant for coarser discretization as typically required in multiband calculations. At low frequency below the energy scale of temperature, the discrete NRG data necessarily needs to be broadened on a linear scale. Here we provide a method that minimizes transition artifacts in between these broadening kernels.

  16. Stark broadening data for stellar plasma research.

    NASA Astrophysics Data System (ADS)

    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.

  17. Anomalous broadening in driven dissipative Rydberg systems

    NASA Astrophysics Data System (ADS)

    Boulier, Thomas; Goldschmidt, Elizabeth; Brown, Roger; Koller, Silvio; Young, Jeremy; Gorshkov, Alexey; Rolston, Steven; Porto, James

    2016-05-01

    Due to their strong, long-range, coherently-controllable interactions, Rydberg atoms have been proposed as a basis for quantum information processing and simulation of many-body physics. Using the coherent dynamics of such highly excited atomic states, however, requires addressing challenges posed by the dense spectrum of Rydberg levels, the detrimental effects of spontaneous emission, and strong interactions. We report the observation of interaction-induced broadening of the two-photon 5s-18s Rydberg transition in ultra-cold 87Rb atoms, trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby Rydberg p-states. This dephasing mechanism implies that the timescales available for the coherent addressing of such systems are dramatically shortened, hampering many recent proposals to use Rydberg-dressed atoms for quantum simulation. Now at Physikalisch-Technische Bundesanstalt.

  18. Structured and Unstructured Homeschooling: A Proposal for Broadening the Taxonomy

    ERIC Educational Resources Information Center

    Neuman, Ari; Guterman, Oz

    2017-01-01

    In recent decades, parental involvement in their children's education has been steadily increasing. Perhaps the ultimate form of parental involvement is the phenomenon called elective home education--EHE (also known as homeschooling). It is customary to divide EHE into two categories according to the degree of structure: "structured EHE"…

  19. Rayleigh-backscattering doppler broadening correction for differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Fan, Lanlan; Zhang, Yinchao; Chen, Siying; Guo, Pan; Chen, He

    2015-11-01

    The spectral broadening by Rayleigh backscattering can cause large changes in water vapor echo signals, causing errors when the water vapor concentration is inversed by differential absorption lidar (DIAL). A correction algorithm is proposed to revise the errors due to the effect of laser spectral broadening. The relative errors of water vapor are calculated in cases of different aerosol distribution and temperature changes before and after correction. The results show that measurement errors due to the Doppler broadening are more than 5% before correction and a 2% measurement error after corrected for the case of a smooth, background aerosol distribution. However, due to the high aerosol gradients and strong temperature inversion, errors can be up to 40% and 10% with no corrections for this effect, respectively. The relative errors can reduce to less than 2% after correction. Hence, the correction algorithm for Rayleigh Doppler broadening can improve detection accuracy in H2O DIAL measurements especially when it is applied to high aerosol concentration or strong temperature inversion.

  20. Pressure broadening of oxygen by water

    NASA Astrophysics Data System (ADS)

    Drouin, Brian J.; Payne, Vivienne; Oyafuso, Fabiano; Sung, Keeyoon; Mlawer, Eli

    2014-01-01

    A need for precise air-mass retrievals utilizing the near-infrared O2 A-band has motivated measurements of the water-broadening in oxygen. Experimental challenges have resulted in very little water broadened oxygen data. Existing water broadening data for the O2 A-band is of insufficient precision for application to the atmospheric data. Line shape theory suggests that approximate O2 pressure broadening parameters for one spectral region, such as the A-band, may be obtained from comparable spectral regions such as the O2 60 GHz Q-branch, which is also used prominently in remote sensing. We have measured precise O2-H2O broadening for the 60 GHz Q-branch and the pure-rotational transitions at room temperature with a Zeeman-modulated absorption cell using a frequency-multiplier spectrometer. Intercomparisons of these data and other O2 pressure broadening data sets confirm the expectation of only minor band-to-band scaling of pressure broadening. The measurement provides a basis for fundamental parameterization of retrieval codes for the long-wavelength atmospheric measured values. Finally, we demonstrate the use of these measurements for retrievals of air-mass via remote sensing of the oxygen A-band.

  1. Charge Correlations in Plasma Line Broadening

    SciTech Connect

    Wrighton, Jeffrey M.; Dufty, James W.

    2008-10-22

    The traditional theory of plasma line broadening is re-examined to correct for phenom-enological assumptions regarding charge correlations. Conditions for static ions are assumed, and the ion microfield distribution is introduced without neglecting ion-electron correlations, and with a precise definition for the ion field at the radiator. Radiator and plasma subsystems are defined so as to make a second order calculation of electron broadening valid for the case of high Z radiators. The electron broadening operator is identified in terms of the fluctuation of the electron density at the radiator, averaged over the entire plasma constrained by a given value for the ion microfield.

  2. Thermally induced microstrain broadening in hexagonal zinc

    SciTech Connect

    Lawson, Andrew C; Valdez, James A; Roberts, Joyce A; Leineweber, Andreas; Mittemeijer, E J; Kreher, W

    2008-01-01

    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.

  3. Computing the inhomogeneous broadening of electronic transitions in solution: a first-principle quantum mechanical approach.

    PubMed

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

    2011-10-14

    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.

  4. Multispectral Imaging Broadens Cellular Analysis

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Amnis Corporation, a Seattle-based biotechnology company, developed ImageStream to produce sensitive fluorescence images of cells in flow. The company responded to an SBIR solicitation from Ames Research Center, and proposed to evaluate several methods of extending the depth of field for its ImageStream system and implement the best as an upgrade to its commercial products. This would allow users to view whole cells at the same time, rather than just one section of each cell. Through Phase I and II SBIR contracts, Ames provided Amnis the funding the company needed to develop this extended functionality. For NASA, the resulting high-speed image flow cytometry process made its way into Medusa, a life-detection instrument built to collect, store, and analyze sample organisms from erupting hydrothermal vents, and has the potential to benefit space flight health monitoring. On the commercial end, Amnis has implemented the process in ImageStream, combining high-resolution microscopy and flow cytometry in a single instrument, giving researchers the power to conduct quantitative analyses of individual cells and cell populations at the same time, in the same experiment. ImageStream is also built for many other applications, including cell signaling and pathway analysis; classification and characterization of peripheral blood mononuclear cell populations; quantitative morphology; apoptosis (cell death) assays; gene expression analysis; analysis of cell conjugates; molecular distribution; and receptor mapping and distribution.

  5. Sound pulse broadening in stressed granular media

    NASA Astrophysics Data System (ADS)

    Langlois, Vincent; Jia, Xiaoping

    2015-02-01

    The pulse broadening and decay of coherent sound waves propagating in disordered granular media are investigated. We find that the pulse width of these compressional waves is broadened when the disorder is increased by mixing the beads made of different materials. To identify the responsible mechanism for the pulse broadening, we also perform the acoustic attenuation measurement by spectral analysis and the numerical simulation of pulsed sound wave propagation along one-dimensional disordered elastic chains. The qualitative agreement between experiment and simulation reveals a dominant mechanism by scattering attenuation at the high-frequency range, which is consistent with theoretical models of sound wave scattering in strongly random media via a correlation length.

  6. Collisional broadening of CO2 IR lines. II. Calculations

    NASA Astrophysics Data System (ADS)

    Rosenmann, L.; Hartmann, J. M.; Perrin, M. Y.; Taine, J.

    1988-03-01

    The ability of available theoretical models in describing broadening mechanisms is tested for the CO2-O2, CO2-CO2, and CO2-N2 systems. It is shown that the Anderson-Tsao-Curnutte theory is inaccurate since short-range forces can contribute significantly to broadening. We use the approach of Robert and Bonamy, but the usual expansion of the atom-atom potential to the fourth order around the intermolecular distance appears insufficient at short distances for these particular systems. We propose a better representation of the radial dependence of the atom-atom potential, while keeping the previous analytical expression of the cross section. Satisfactory results are obtained for both the rotational quantum number dependence of room-temperature CO2-O2, CO2-CO2, and CO2-N2 half-widths and the evolution of CO2-N2 broadening with temperature. It is shown that the isotropic part of the potential involved in the trajectory calculation must be coherently deduced from the atom-atom interaction potential.

  7. Calculation of gain and luminescence spectra of quantum-cascade laser structures taking into account asymmetric emission line broadening

    SciTech Connect

    Ushakov, D V; Manak, I S; Kononenko, V K

    2010-05-26

    The energy levels, wave functions, and matrix elements of optical dipole transitions are calculated numerically for superlattice quantum-cascade structures. The effect of spectral broadening on the shape of emission spectra is estimated and semiphenomenological asymmetric profiles of emission line broadening are proposed. It is shown that the electroluminescence spectra well agree with the calculated spontaneous recombination spectra. (lasers)

  8. Unified classical path theories of pressure broadening.

    NASA Technical Reports Server (NTRS)

    Bottcher, C.

    1971-01-01

    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.

  9. Broadening Our View of Linguistic Diversity

    ERIC Educational Resources Information Center

    O'Neal, Debra; Ringler, Marjorie

    2010-01-01

    The definition of English language learners needs to be broadened to include the marginalized dialects of English. Not all native speakers speak Standard English, and even those who do need to learn Academic English to succeed in school. By using strategies developed for ELLs, teachers can help all students become fluent in the language of school.

  10. Broadening Our View of Linguistic Diversity

    ERIC Educational Resources Information Center

    O'Neal, Debra; Ringler, Marjorie

    2010-01-01

    The definition of English language learners needs to be broadened to include the marginalized dialects of English. Not all native speakers speak Standard English, and even those who do need to learn Academic English to succeed in school. By using strategies developed for ELLs, teachers can help all students become fluent in the language of school.

  11. Broadening the potential bandwidth of piezoelectric transducers by partial depolarization

    SciTech Connect

    Hariti, Sid Ahmed; Hole, Stephane; Lewiner, Jacques

    2001-06-18

    Elastic waves are used more and more in a nondestructive way to probe the physical properties of materials. The resolution of the images or the accuracy of the measurements is directly associated with the ultrasonic signal bandwidth and amplitude a system can generate or detect. The authors propose a technique to broaden the potential bandwidth of piezoelectric generators and sensors, which is based on utilizing a nonuniformly-polarized piezoelectric material. Both simulated and experimental responses are shown. They are in good agreement and exhibit a useful bandwidth over several natural harmonics of the piezoelectric transducer. {copyright} 2001 American Institute of Physics.

  12. OBSERVATIONAL EVIDENCE FOR A CORRELATION BETWEEN MACROTURBULENT BROADENING AND LINE-PROFILE VARIATIONS IN OB SUPERGIANTS

    SciTech Connect

    Simon-Diaz, S.; Herrero, A.; Castro, N.; Uytterhoeven, K.; Puls, J.

    2010-09-10

    The spectra of O and B supergiants (Sgs) are known to be affected by a significant form of extra line broadening (usually referred to as macroturbulence) in addition to that produced by stellar rotation. Recent analyses of high-resolution spectra have shown that the interpretation of this line broadening as a consequence of large-scale turbulent motions would imply highly supersonic velocity fields in photospheric regions, making this scenario quite improbable. Stellar oscillations have been proposed as a likely alternative explanation. As part of a long-term observational project, we are investigating the macroturbulent broadening in O and B Sgs and its possible connection with spectroscopic variability phenomena and stellar oscillations. In this Letter, we present the first encouraging results of our project, namely, firm observational evidence for a strong correlation between the extra broadening and photospheric line-profile variations in a sample of 13 Sgs with spectral types ranging from O9.5 to B8.

  13. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields

    SciTech Connect

    Wei, Zhiliang; Yang, Jian; Lin, Yanqin E-mail: chenz@xmu.edu.cn; Chen, Zhong E-mail: chenz@xmu.edu.cn; Chen, Youhe

    2015-04-07

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  14. Line broadening interference for high-resolution nuclear magnetic resonance spectra under inhomogeneous magnetic fields.

    PubMed

    Wei, Zhiliang; Yang, Jian; Chen, Youhe; Lin, Yanqin; Chen, Zhong

    2015-04-07

    Nuclear magnetic resonance spectroscopy serves as an important tool for analyzing chemicals and biological metabolites. However, its performance is subject to the magnetic-field homogeneity. Under inhomogeneous fields, peaks are broadened to overlap each other, introducing difficulties for assignments. Here, we propose a method termed as line broadening interference (LBI) to provide high-resolution information under inhomogeneous magnetic fields by employing certain gradients in the indirect dimension to interfere the magnetic-field inhomogeneity. The conventional spectral-line broadening is thus interfered to be non-diagonal, avoiding the overlapping among adjacent resonances. Furthermore, an inhomogeneity correction algorithm is developed based on pattern recognition to recover the high-resolution information from LBI spectra. Theoretical deductions are performed to offer systematic and detailed analyses on the proposed method. Moreover, experiments are conducted to prove the feasibility of the proposed method for yielding high-resolution spectra in inhomogeneous magnetic fields.

  15. Spectral line broadening in magnetized black holes

    SciTech Connect

    Frolov, Valeri P.; Shoom, Andrey A.; Tzounis, Christos E-mail: ashoom@ualberta.ca

    2014-07-01

    We consider weakly magnetized non-rotating black holes. In the presence of a regular magnetic field the motion of charged particles in the vicinity of a black hole is modified. As a result, the position of the innermost stable circular orbit (ISCO) becomes closer to the horizon. When the Lorentz force is repulsive (directed from the black hole) the ISCO radius can reach the gravitational radius. In the process of accretion charged particles (ions) of the accreting matter can be accumulated near their ISCO, while neutral particles fall down to the black hole after they reach 6M radius. The sharp spectral line Fe α, emitted by iron ions at such orbits, is broadened when the emission is registered by a distant observer. In this paper we study this broadening effect and discuss how one can extract information concerning the strength of the magnetic field from the observed spectrum.

  16. Modulation Broadening of Unsaturated Lorentzian Lines

    DTIC Science & Technology

    1961-11-01

    the JOURNAL OF CHEMICAL PHYSICS , Vol. 35, No. 5, 1708-1710, November, 1961 Printed in U. S. A. Modulation Broadening of Unsaturated Lorentzian Lines* HuGo WAHLQuIST Jet Propulsion Laboratory, California Instilute of Technology, Pasadena, California (Received April 7, 1961) Closed, analytic expressions are obtained for the harmonic amplitudes which arise in the modulation of unsaturated Lorentzian absorption lines. Exact formulas relating characteristics of the observed signals (amplitude, width, slope ratios, etc.) to the

  17. Stark broadening effect and zirconium conflict problem

    NASA Astrophysics Data System (ADS)

    Dimitrijević, Milan S.; Popović, Luka Č.; Milovanović, Nenad

    2001-04-01

    Using the Modified Semiempirical Method we have calculated the electron-impact widths for four singly and doubly ionized zirconium UV lines of astrophysical importance. Using the SYNTH and ATLAS9 codes for stellar atmospheres similar to that of the HgMn star χ Lupi we have synthesized the line profiles and found equivalent widths for these lines. The influence of the Stark broadening effect on abundance determination and its contribution to the so-called ``zirconium conflict'' are discussed. .

  18. Line Broadening and the Solar Opacity Problem

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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.

  19. Broadening the diagnosis of bipolar disorder: benefits vs. risks

    PubMed Central

    STRAKOWSKI, STEPHEN M.; FLECK, DAVID E.; MAJ, MARIO

    2011-01-01

    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

  20. Signal broadening in the laser Doppler velocimeter.

    NASA Technical Reports Server (NTRS)

    Angus, J. C.; Edwards, R. V.; Dunning, J. W., Jr.

    1971-01-01

    Critical review of a recent paper in which Denison, Stevenson, and Fox (1971) discussed the sources of spectral broadening in the laser Doppler velocimeter. It is pointed out that, in their discussion, the above-mentioned authors indicated that the spread in wave vectors of the incident and detected fields and the finite length of time a scattering center stayed in the sample volume each contributed separately and independently to the observed spectral width of the scattered radiation. This statement is termed incorrect, and it is shown that the two effects are one and the same.

  1. Action potential broadening in a presynaptic channelopathy

    PubMed Central

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

    2016-01-01

    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. PMID:27381274

  2. Action potential broadening in a presynaptic channelopathy.

    PubMed

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

    2016-07-06

    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 Ca(2+) influx and GABA release, and decreased spontaneous Purkinje cell firing. We find no evidence for developmental compensation for inherited Kv1.1 dysfunction.

  3. Action potential broadening in a presynaptic channelopathy

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    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.

  4. Commitment to Broadening Participation at NOAO

    NASA Astrophysics Data System (ADS)

    Garmany, Catharine D.; Norman, D.

    2011-01-01

    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.

  5. Classical trajectory versus quantum interference. A linear chain model for the origin of uncertainty broadening

    SciTech Connect

    Tang, Jau

    1996-02-01

    A simple linear chain model, as an alternative to the orthodox Schroedinger approach, is proposed to explain the origin of the uncertainty broadening and to improve our physical insight into the difference between classical and quantum worlds. Quantum interference in space is manifested as a result of fast exchange between adjacent particles of different internal degrees of freedom.

  6. Broaden Engineering Technology students' knowledge through hands-on with motion robotics

    USDA-ARS?s Scientific Manuscript database

    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...

  7. America's economic future: environmentalists broaden the industrial policy debate

    SciTech Connect

    Not Available

    1984-01-01

    America's future economic health depends on the condition of our natural resources, our human resources, and our agricultural, energy, service, and high-technology industries, as well as on the traditional manufacturing industries. Industrial structure and output will do much to determine future levels of pollutants and resource use, and the shape of our economy will influence the character of American society and the quality of American life. The debate over proposals for government intervention in the growth and decline of specific industries changes the focus to microeconomic issues and broadens the discussion of economic goals. Environmentalists offer five goals for (1) a sustainable global economy, (2) a higher quality of life, (3) a sustainable environment and resource base, (4) total employment, and (5) widespread participation in decisions. They offer specific courses of action to meet these goals.

  8. A holographic method to measure the source size broadening in STEM.

    PubMed

    Verbeeck, Jo; Béché, Armand; Van den Broek, Wouter

    2012-09-01

    Source size broadening is an important resolution limiting effect in modern STEM experiments. Here, we propose an alternative method to measure the source size broadening making use of a holographic biprism to create interference patterns in an 'empty' Ronchigram. This allows us to measure the exact shape of the source size broadening with a much better sampling than previously possible. We find that the shape of the demagnified source deviates considerably from a Gaussian profile that is often assumed. We fit the profile with a linear combination of a Gaussian and a bivariate Cauchy distribution showing that even though the full width at half maximum is similar to previously reported measurements, the tails of the profile are considerable wider. This is of fundamental importance for quantitative comparison of STEM simulations with experiments as these tails make the image contrast dependent on the interatomic distance, an effect that cannot be reproduced by a single Gaussian profile of fixed width alone.

  9. Broadening Participation in the Coastal Environmental Sciences

    NASA Astrophysics Data System (ADS)

    Christian, A.; Hannigan, R.

    2011-12-01

    Embracing diversity of discipline and perspective is central to broadening participation in the ocean sciences. Research focused on coastal environmental issues seen through the lenses of indigenous knowledge, industry, and public-private partnership perspectives engages younger non-ocean science students from minority serving institutions in unique ways. Demonstrating multiple entry points to students interested in a career in the sciences and engaging them in research across spatial and temporal scales is vitally important to the creation of a learning cohort that will sustain these students past their often short summer research experience. By combining recruitment partnerships with select minority serving institutions, engaging younger students in research, and creating a diverse set of cohort building activities ensures that as we embrace the diversity of coastal environmental disciplines we also embrace the diversity of perspectives that these students bring to our research.

  10. Coherent Forward Broadening in Cold Atom Clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, Francis

    2016-05-01

    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 wavefunction 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. This work was supported by the National Science Foundation under Grant No. 1404419-PHY.

  11. Coherent forward broadening in cold atom clouds

    NASA Astrophysics Data System (ADS)

    Sutherland, R. T.; Robicheaux, F.

    2016-02-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Furthermore, 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 at the back of the cloud are more excited than the atoms at the front. These calculations are conducted at the low densities relevant to recent experiments.

  12. Photoinduced broadening of cholesteric liquid crystal reflectors

    NASA Astrophysics Data System (ADS)

    White, Timothy J.; Freer, Alexander S.; Tabiryan, Nelson V.; Bunning, Timothy J.

    2010-04-01

    The selective reflection of cholesteric liquid crystals (CLCs) is well-known and has been utilized in a number of dynamic optical applications. This work presents a novel approach to passively (e.g., all-optically) cue reflection notch broadening in photoresponsive CLC formulations based on high helical twisting power (HTP) bis(azo) chiral dopants. The original reflection bandwidth of approximately 100 nm is increased to as much as 1700 nm, by exposing 36 μm thick cells to UV light. The maximum attainable bandwidth is shown to be a function of cell thickness, light intensity, and strongly related to the HTP of the photoresponsive chiral dopants. An all-optical technique of simultaneous UV and green light exposure is demonstrated to trap the reflection notch at a predetermined position and bandwidth.

  13. Phonon broadening in high entropy alloys

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

    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.

  14. Collision Broadening Of Line Spectrum In Sonoluminescence

    SciTech Connect

    Li Chaohui; An Yu

    2008-06-24

    The direct measurement of temperature inside a sonoluminescing bubble as it is at its flashing phase is almost impossible due to the smallness of the bubble and the short duration of the flashing. One may estimate the temperature through fitting the continuum spectrum of sonoluminescence by the black body radiation formula, or fitting the shape of atomic or molecular line spectrum (the different temperature, density and pressure result in the different shape of the line spectrum due to the effect of collision broadening). However, the temperature changes in a huge range at short duration as the bubble flashes, therefore, the observed spectra are some kind of average one, so are those fitted results. To evaluate the instantaneous temperature more accurately, we simulate the processes of the bubble motion and the thermodynamics inside the bubble, in which atomic or molecular line spectra with the collision broadening effect and the continuum spectra contributed from the processes of electron-atom bremsstrahlung, electron-ion bremsstrahlung and recombination radiation and radiative attachment of electrons to atoms and molecules are taken into account in calculating the light emission. If both the calculated continuum spectra and the shape of line spectra can well represent the experimental data, we may deduce that the calculation of the temperature, density and pressure is reliable and we indirectly evaluate those quantities inside the bubble. In the present calculation, the line spectra of OH radical at about 310 nm mixing the electron transition with the vibration and rotational bands are considered. The calculation qualitatively consists with the observation, and we expect that with the more precise bubble dynamics model instead of the uniform model employed in the present calculation we may improve the quantitative result.

  15. Exact expression of the impact broadening operator for hydrogen Stark broadening

    NASA Astrophysics Data System (ADS)

    Gigosos, M. A.; González, M. Á.; Talin, B.; Calisti, A.

    2007-05-01

    Aims:Recent measurements on the Stark broadening of radio recombination lines show values and trends in disagreement with conventional theories. Different attemps to explain those disagreements have not been successfull for any of the employed theoretical models. In particular, the impact model that describes well the physical conditions at which the studied broadenings occur, shows a functional trend upon the principal quantum number of the studied transitions that does not correspond to the experimental observations. Methods: High values of the principal quantum number require computable formulas for the calculation of transition probabilities. Some of those expressions have been published, leading to approximate formulas on the dependence of the line width versus the principal quantum number of the upper level of the transition. Results: In this work an exact expression for the hydrogen Stark width in the frame of impact approximation is given.

  16. The NO Vibrational Fundamental Band: O2-Broadening Coefficients

    NASA Technical Reports Server (NTRS)

    Freedman, R. S.; Giver, L. P.; Gore, Warren J. Y. (Technical Monitor)

    1997-01-01

    Rovibrational spectra of the vibrational fundamental of nitric oxide at 1875 cm-1 have been recorded under O2-broadening conditions at 296 K and 0.0056 cm-1 resolution using the Solar Nemeth FTS at the Kitt Peak National Observatory. The use of a flow system, which maintains the NO2 at trace levels, has enabled the first measurement of these broadening coefficients. The broadening of the trace contaminant, N2O, allowed checks of the measured pressures. The least-squares analysis of the spectra includes the nuclear hyperfine structure in addition to (lambda) doubling. We observed differential broadening between the e and f (lambda) components of 2II 1/2 transitions as well as larger differences in broadening observed between 2II3/2 transitions.

  17. X-Ray Diffraction Line Broadening: Modeling and Applications to High-Tc Superconductors

    PubMed Central

    Balzar, Davor

    1993-01-01

    A method to analyze powder-diffraction line broadening is proposed and applied to some novel high-Tc superconductors. Assuming that both size-broadened and strain-broadened profiles of the pure-specimen profile are described with a Voigt function, it is shown that the analysis of Fourier coefficients leads to the Warren-Averbach method of separation of size and strain contributions. The analysis of size coefficients shows that the “hook” effect occurs when the Cauchy content of the size-broadened profile is underestimated. The ratio of volume-weighted and surface-weighted domain sizes can change from ~1.31 for the minimum allowed Cauchy content to 2 when the size-broadened profile is given solely by a Cauchy function. If the distortion co-efficient is approximated by a harmonic term, mean-square strains decrease linearly with the increase of the averaging distance. The local strain is finite only in the case of pure-Gauss strain broadening because strains are then independent of averaging distance. Errors of root-mean-square strains as well as domain sizes were evaluated. The method was applied to two cubic structures with average volume-weighted domain sizes up to 3600 Å, as well as to tetragonal and orthorhombic (La-Sr)2CuO4, which exhibit weak line broadenings and highly overlapping reflections. Comparison with the integral-breadth methods is given. Reliability of the method is discussed in the case of a cluster of the overlapping peaks. The analysis of La2CuO4 and La1.85M0.15CuO4(M = Ca, Ba, Sr) high-Tc superconductors showed that microstrains and incoherently diffracting domain sizes are highly anisotropic. In the superconductors, stacking-fault probability increases with increasing Tc; microstrain decreases. In La2CuO4, different broadening of (h00) and (0k0) reflections is not caused by stacking faults; it might arise from lower crystallographic symmetiy. The analysis of Bi-Cu-O superconductors showed much higher strains in the [001] direction than in

  18. Droplet spectral broadening in marine stratus

    SciTech Connect

    Hudson, J.G.; Yum, Seong Soo

    1997-11-15

    Broadening of the cloud droplet (diameter < 50 {mu}m) spectrum with increased droplet size was found to depend on the vertical profiles of cloud water. Clouds with liquid water profiles resembling adiabatic conditions displayed constant spectral widths. Other clouds displayed broader droplet spectra and increasing broadness with mean droplet sizes. Less than adiabatic cloud liquid water profiles may be accounted for by conversion to drops (diameter > 50 {mu}m, i.e., drizzle). Broad droplet spectra were most closely associated with drizzle drops. Both the concentration, C and slope, k, of the cloud condensation nuclei (CCN) spectra were theoretically found to affect droplet spectral width. For individual cloud parcels a higher C and lower k each contributed to broader droplet spectra. When mixing among cloud parcels with different updrafts was considered, the predictions deviated especially at larger mean droplet diameters. Variations in updraft velocity result in differences in droplet concentrations and mean droplet sizes. The predictions for this internal mixing process showed greater droplet spectral widths for CCN spectra with higher k, especially at the larger mean droplet diameters. Instead of the individual parcel predictions of narrower droplet spectra at larger mean droplet sizes, internal mixing predicted increasing droplet spectral width with increasing mean droplet size. These predictions are consistent with the observations. First, when only cloud parcels with small mean droplet diameters (< 1 {mu}m) were considered, the polluted clouds that formed on CCN with higher C and lower k displayed broader droplet spectra than clean clouds. Cloud parcels with large mean droplet diameters (>12 {mu}m) and large {sigma} were observed only in clean conditions where k was high. Increasing droplet spectral width with mean droplet diameter (especially > 12 {mu}m) is typical of many observations here and elsewhere.

  19. Zero-broadening SBS slow light propagation in an optical fiber using two broadband pump beams.

    PubMed

    Wang, Shihe; Ren, Liyong; Liu, Yu; Tomita, Yasuo

    2008-05-26

    A new method of tailoring stimulated Brillouin scattering (SBS) gain spectrum for slow light propagation is proposed by use of two Gaussian-shaped broadband pump beams with different powers and spectral widths. The central frequency interval between the two pump beams are carefully set to be two inherent Brillouin frequency shift, ensuring that the gain spectrum of one pump has the same central frequency with the loss spectrum of the other one. Different gain profiles are obtained and analyzed. Among them a special gain profile is found that ensures a zero-broadening of the signal pulse independent of the Brillouin gain. This is owing to the compensation between the positive gain-dependent broadening and the negative GVD (group velocity dispersion) dependent broadening. The relationship of two pump beams is also found for constructing such a gain profile. It provides us a new idea of managing the broadening of SBS-based slow pulse by artificially constructing and optimizing the profile of gain spectrum.

  20. Radial velocity signatures of Zeeman broadening

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Shulyak, D.; Anglada-Escudé, G.; Jeffers, S. V.; Morin, J.; Zechmeister, M.; Kochukhov, O.; Piskunov, N.

    2013-04-01

    Stellar activity signatures such as spots and plages can significantly limit the search for extrasolar planets. Current models of activity-induced radial velocity (RV) signals focus on the impact of temperature contrast in spots according to which they predict the signal to diminish toward longer wavelengths. The Zeeman effect on RV measurements counteracts this: the relative importance of the Zeeman effect on RV measurements should grow with wavelength because the Zeeman displacement itself grows with λ, and because a magnetic and cool spot contributes more to the total flux at longer wavelengths. In this paper, we model the impact of active regions on stellar RV measurements including both temperature contrast in spots and line broadening by the Zeeman effect. We calculate stellar line profiles using polarized radiative transfer models including atomic and molecular Zeeman splitting over large wavelength regions from 0.5 to 2.3 μm. 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; a spot magnetic field of ~1000 G can produce a similar RV amplitude as a spot temperature contrast of ~1000 K. Furthermore, the RV signal caused by cool and magnetic spots increases with wavelength, in contrast to the expectation from temperature contrast alone. We also calculate the RV signal caused by variations in average magnetic field strength from one observation to the next, for example due to a magnetic cycle, but find it unlikely that this can significantly influence the search for extrasolar planets. As an example, we derive the RV amplitude of the active M dwarf AD Leo as a function of wavelength using data from the HARPS spectrograph. Across this limited wavelength range, the RV signal does not diminish at longer wavelengths but shows evidence for the opposite behavior, consistent with a strong influence of the Zeeman effect. We conclude that the RV signal of active stars does

  1. Medium induced transverse momentum broadening in hard processes

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related PT broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium PT broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.

  2. abo-cross: Hydrogen broadening cross-section calculator

    NASA Astrophysics Data System (ADS)

    Barklem, P. S.; Anstee, S. D.; O'Mara, B. J.

    2015-07-01

    Line broadening cross sections for the broadening of spectral lines by collisions with neutral hydrogen atoms have been tabulated by Anstee & O'Mara (1995), Barklem & O'Mara (1997) and Barklem, O'Mara & Ross (1998) for s-p, p-s, p-d, d-p, d-f and f-d transitions. abo-cross, written in Fortran, interpolates in these tabulations to make these data more accessible to the end user. This code can be incorporated into existing spectrum synthesis programs or used it in a stand-alone mode to compute line broadening cross sections for specific transitions.

  3. NASA broadened-specification fuels combustion technology program

    NASA Technical Reports Server (NTRS)

    Fear, J. S.

    1980-01-01

    The broadened-Specification Fuels Combustion Technology program's purpose is to evolve and demonstrate the technology required to enable current and next generation high-thrust, high-bypass-ratio turbofan engines to use fuels with broadened properties and to verify the evolved technology in full scale engine tests. The three phases of the program are combustor concept screening, combustor optimization testing, and engine verification testing. Constraints for designing combustion systems are outlined and problems to be expected in the use of broadened properties fuels are listed.

  4. Meta-Research: Broadening the Scope of PLOS Biology.

    PubMed

    Kousta, Stavroula; Ferguson, Christine; Ganley, Emma

    2016-01-01

    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.

  5. SOLAR WIND STRAHL BROADENING BY SELF-GENERATED PLASMA WAVES

    SciTech Connect

    Pavan, J.; Gaelzer, R.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F. E-mail: rudi@ufpel.edu.br E-mail: yoonp@umd.edu

    2013-06-01

    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.

  6. Doppler broadening in the β-proton- γ decay sequence

    NASA Astrophysics Data System (ADS)

    Schwartz, Sarah; Wrede, C.; 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.

    2015-10-01

    We report the first observation of Doppler-broadening in β delayed proton- γ decay. The broadening occurs because the daughter nucleus γ decays while recoiling from proton emission. A method to analyze β delayed nucleon emission was applied to two Doppler-broadened 25Al peaks from the 26P(βpγ)25Al decay. The method was first tested on the broad 1613 keV γ-ray peak using known center-of-mass proton energies as constraints. The method was then applied to the 1776 keV γ-ray peak from the 2720 keV excited state of 25Al. The broadening was used to determine a 26Si excitation energy of 13.3 +/- 1.0 (stat.) +/- 0.7 (syst.) MeV. This energy is consistent with proton emission from the known T = 2 isobaric analog state of 26P in 26Si.

  7. Frequency band broadening of magnetospheric VLF emissions near the equator

    NASA Technical Reports Server (NTRS)

    Maeda, K.; Lin, C. S.

    1981-01-01

    The broadening of the whistler mode VLF emission band has frequently been observed by the equatorially orbiting S3-A (Explorer 45) satellite outside the midnight sector of the plasmasphere, during periods of geomagnetic disturbance. Prior to the broadening, the band of this emission is narrow with a sharp gap at the half electron gyrofrequency. The gradual broadening of the emission band on the low-frequency side is associated with the simultaneously observed spreading of the anisotropy of the ring current electrons to higher and wider energy ranges. Using the modeled distribution function, the linear growth rates of the cyclotron instability are calculated numerically. The results suggest that broadening of the VLF emission band near the plasmasphere can be caused by spreading of the ring current electron anisotropy toward higher energies.

  8. Solar Wind Strahl Broadening by Self-Generated Plasma Waves

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

  9. Pressure broadening of CO and OCS spectral lines

    NASA Astrophysics Data System (ADS)

    Bouanich, J.-P.; Blanquet, G.

    1988-09-01

    This paper reviews the principal features of two semiclassical impact theories of collisional line-broadening, Anderson (1949) and Tsao-Curnutte (1962) theory and the more recent theory of Robert and Bonamy (1979). These models are applied to the calculation of self-, N2-, O2- and CO2-broadened line widths of CO and of self-, O2-, and N2-broadened linewidths of OCS. In addition to the electrostatic interactions, two anisotropic potentials are considered: a simple one governing dispersion interaction and a more elaborate atom-atom interaction potential. Selected experimental values for broadening coefficients of CO and OCS at room temperature and around 200 K are compared with the theoretical values. Conclusions on the two theories and the intermolecular potentials used are drawn from this comparison.

  10. Collision Broadening Using Alkali-Filled, Hollow Core Fibers

    DTIC Science & Technology

    2007-09-01

    spectrum should collisionally broaden due to the presence of fiber walls, as opposed to the more common pressure broadening method. An absorption dip...laser design will include an optical cavity and a gain medium......................... 6 2.4. The more common type of laser...37 3.8. a) The basic mount used at the vacuum side of the setup. b) The cesium mount was more elaborate

  11. Self-phase-modulation induced spectral broadening in silicon waveguides.

    PubMed

    Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram

    2004-03-08

    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.

  12. Coherent and incoherent spectral broadening in a photonic crystal fiber.

    PubMed

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

    2007-07-01

    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.

  13. It's Time To Broaden the Agenda.

    ERIC Educational Resources Information Center

    Krugman, Richard D.

    1998-01-01

    This keynote address reviews previous efforts at developing a research policy agenda for child abuse and neglect, reviews medical research directions in child sexual abuse, suggests the author's views of potential research areas, and suggests a policy infrastructure to further implementation of the conference's proposals. (DB)

  14. The broaden-and-build theory of positive emotions.

    PubMed Central

    Fredrickson, Barbara L

    2004-01-01

    The broaden-and-build theory describes the form and function of a subset of positive emotions, including joy, interest, contentment and love. A key proposition is that these positive emotions broaden an individual's momentary thought-action repertoire: joy sparks the urge to play, interest sparks the urge to explore, contentment sparks the urge to savour and integrate, and love sparks a recurring cycle of each of these urges within safe, close relationships. The broadened mindsets arising from these positive emotions are contrasted to the narrowed mindsets sparked by many negative emotions (i.e. specific action tendencies, such as attack or flee). A second key proposition concerns the consequences of these broadened mindsets: by broadening an individual's momentary thought-action repertoire--whether through play, exploration or similar activities--positive emotions promote discovery of novel and creative actions, ideas and social bonds, which in turn build that individual's personal resources; ranging from physical and intellectual resources, to social and psychological resources. Importantly, these resources function as reserves that can be drawn on later to improve the odds of successful coping and survival. This chapter reviews the latest empirical evidence supporting the broaden-and-build theory and draws out implications the theory holds for optimizing health and well-being. PMID:15347528

  15. Research on Fast-Doppler-Broadening of neutron cross sections

    SciTech Connect

    Li, S.; Wang, K.; Yu, G.

    2012-07-01

    A Fast-Doppler-Broadening method is developed in this work to broaden Continuous Energy neutron cross-sections for Monte Carlo calculations. Gauss integration algorithm and parallel computing are implemented in this method, which is unprecedented in the history of cross section processing. Compared to the traditional code (NJOY, SIGMA1, etc.), the new Fast-Doppler-Broadening method shows a remarkable speedup with keeping accuracy. The purpose of using Gauss integration is to avoid complex derivation of traditional broadening formula and heavy load of computing complementary error function that slows down the Doppler broadening process. The OpenMP environment is utilized in parallel computing which can take full advantage of modern multi-processor computers. Combination of the two can reduce processing time of main actinides (such as {sup 238}U, {sup 235}U) to an order of magnitude of 1{approx}2 seconds. This new method is fast enough to be applied to Online Doppler broadening. It can be combined or coupled with Monte Carlo transport code to solve temperature dependent problems and neutronics-thermal hydraulics coupled scheme which is a big challenge for the conventional NJOY-MCNP system. Examples are shown to determine the efficiency and relative errors compared with the NJOY results. A Godiva Benchmark is also used in order to test the ACE libraries produced by the new method. (authors)

  16. Low Arousing Positive Affect Broadens Visual Attention and Alters the Thought-Action Repertoire While Broadened Visual Attention Does Not

    PubMed Central

    Jäger, Daniel T.; Rüsseler, Jascha

    2016-01-01

    The Broaden-and-Build Theory states that positive emotions broaden cognition and therefore build personal resources. However, missing theoretical precision regarding the interaction of the cognitive processes involved offers a variety of possible explanations for the mechanisms of broadening and building. In Experiment 1 we tested the causality assumption which states that positive emotions first broaden visual attention which in turn leads to broadened cognition. We examined the effects of a broadened, narrowed or neutral attentional scope of 72 subjects (30 men) on their momentary thought-action repertoire. Results showed that there were no significant differences between groups regarding the breadth or the content of the thought-action repertoire. In Experiment 2 we studied the non-causality hypothesis which assumes a non-causal relationship between cognitive processes. We did so by investigating the effects of negative, neutral, and positive affect on the visual attentional scope of 85 subjects (41 men) in Experiment 2a, as well as on the thought-action repertoire of 85 participants (42 men) in Experiment 2b. Results revealed an attentional broadening effect in Experiment 2a but no differences between groups concerning the breadth of the thought-action repertoire in Experiment 2b. However, a theory driven content analysis showed that positive affect promoted social actions. Thus, our results favor the non-causality assumption. Moreover, results indicate that positive emotions do not target personal resources in general but rather resources associated with social behavior. In conclusion, we argue that the Broaden-and-Build Theory should be refined. PMID:27826276

  17. Excessive Balmer line broadening in a plane cathode abnormal glow discharge in hydrogen

    SciTech Connect

    Cvetanovic, N.; Kuraica, M.M.; Konjevic, N.

    2005-02-01

    Results of a Doppler spectroscopy study of the hydrogen Balmer alpha line in an abnormal glow discharge operated in pure hydrogen are reported. Measurements of line shapes are performed side-on to the discharge axis in a low electric field region of negative glow. The excessive Balmer alpha broadening is detected and its presence and linewidth is related to the collisions of fast hydrogen atoms with molecular hydrogen. The collision model enabled also an estimation of effective cross section data from the Balmer alpha axial intensity decay curves. Large excessive Balmer alpha line broadening in pure hydrogen and its dependence upon the direction of observation with respect to the electric field is in contradiction to the resonance transfer model, proposed byMills et al. in several publications [see, e.g., IEEE Trans. Plasma Sci. 31, 338 (2003)].

  18. Photon-pair source with controllable delay based on shaped inhomogeneous broadening of rare-earth-metal-doped solids

    SciTech Connect

    Sekatski, Pavel; Sangouard, Nicolas; Gisin, Nicolas; Afzelius, Mikael; Riedmatten, Hugues de

    2011-05-15

    Spontaneous Raman emission in atomic gases provides an attractive source of photon pairs with a controllable delay. We show how this technique can be implemented in solid state systems by appropriately shaping the inhomogeneous broadening. Our proposal is eminently feasible with current technology and provides a realistic solution to entangle remote rare-earth-metal-doped solids in a heralded way.

  19. A broadened classical master equation approach for nonadiabatic dynamics at metal surfaces: Beyond the weak molecule-metal coupling limit.

    PubMed

    Dou, Wenjie; Subotnik, Joseph E

    2016-01-14

    A broadened classical master equation (BCME) is proposed for modeling nonadiabatic dynamics for molecules near metal surfaces over a wide range of parameter values and with arbitrary initial conditions. Compared with a standard classical master equation-which is valid in the limit of weak molecule-metal couplings-this BCME should be valid for both weak and strong molecule-metal couplings. (The BCME can be mapped to a Fokker-Planck equation that captures level broadening correctly.) Finally, our BCME can be solved with a simple surface hopping algorithm; numerical tests of equilibrium and dynamical observables look very promising.

  20. Theoretical calculation of self-broadening coefficients for the ν5 band of methyl chloride at various temperatures

    NASA Astrophysics Data System (ADS)

    Barbouchi Ramchani, A.; Jacquemart, D.; Dhib, M.; Aroui, H.

    2014-02-01

    Self-broadening coefficients of transitions belonging to the ν5 band of methyl chloride have been calculated using a semi-classical model based on the Anderson-Tsao-Curnutte (ATC) theory, including some improvements proposed by Robert and Bonamy. The calculations show the predominance of the dipole-dipole interaction. To better match the experimental measurements performed at room temperature in our previous work, a cut-off of the intermolecular distance has been used. The rotational J and K dependencies of the calculated self-broadening coefficients have been clearly observed and are consistent with our previous measurements.

  1. Detector resolution in positron annihilation Doppler broadening experiments

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

    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.

  2. Air-broadened linewidths of nitrous oxide: An improved calculation

    NASA Astrophysics Data System (ADS)

    Lacome, Nelly; Levy, Armand; Boulet, Christian

    1983-01-01

    The semiclassical theory developed by Robert and Bonamy was used to obtain the linewidths of N 2O broadened by itself, by N 2 and by O 2. The main features of the formalism are as follows: (a) The anisotropic potential is expressed by using, besides the quadrupole-quadrupole contribution, an atom-atom interaction model (without any adjustable parameter) which takes both long- and short-range forces into account. (b) The geometry of the collision is described through the so-called "equivalent" straight path, more appropriate than the usual one. (c) The matrix elements of the relaxation operator are computed by means of the linked-cluster theorem, so that the treatment remains nonperturbative and no resort to cutoff precedures is needed. In addition to being more realistic the present formalism has the advantage of making the computation tractable for complex molecular systems such as linear-linear ones. Careful comparison was made with the available experimental results. For self-broadened N 2O very satisfactory agreement is obtained both at 300 and 204 K. This is also the case for nitrogen broadening at room temperature. Regarding oxygen-broadened linewidths, very few experimental data exist. Anyway, the present results reveal substantial improvement as compared to the usual calculations based upon Anderson-Tsao-Curnutte model. From these results a predictive tabulation was obtained for the values of air-broadened N 2O linewidths at 300 and 204 K.

  3. Stark Broadening Parameters for Neutral Oxygen Spectral Lines

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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 10 16 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.

  4. Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

    DOE PAGES

    Vogman, G. V.; Shumlak, U.

    2011-10-13

    Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian functionmore » associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. As a result, these measurements are used to gain a better understanding of Z-pinch equilibria.« less

  5. Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

    SciTech Connect

    Vogman, G. V.; Shumlak, U.

    2011-10-13

    Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian function associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. As a result, these measurements are used to gain a better understanding of Z-pinch equilibria.

  6. Deconvolution of Stark broadened spectra for multi-point density measurements in a flow Z-pinch

    SciTech Connect

    Vogman, G. V.; Shumlak, U.

    2011-10-15

    Stark broadened emission spectra, once separated from other broadening effects, provide a convenient non-perturbing means of making plasma density measurements. A deconvolution technique has been developed to measure plasma densities in the ZaP flow Z-pinch experiment. The ZaP experiment uses sheared flow to mitigate MHD instabilities. The pinches exhibit Stark broadened emission spectra, which are captured at 20 locations using a multi-chord spectroscopic system. Spectra that are time- and chord-integrated are well approximated by a Voigt function. The proposed method simultaneously resolves plasma electron density and ion temperature by deconvolving the spectral Voigt profile into constituent functions: a Gaussian function associated with instrument effects and Doppler broadening by temperature; and a Lorentzian function associated with Stark broadening by electron density. The method uses analytic Fourier transforms of the constituent functions to fit the Voigt profile in the Fourier domain. The method is discussed and compared to a basic least-squares fit. The Fourier transform fitting routine requires fewer fitting parameters and shows promise in being less susceptible to instrumental noise and to contamination from neighboring spectral lines. The method is evaluated and tested using simulated lines and is applied to experimental data for the 229.69 nm C III line from multiple chords to determine plasma density and temperature across the diameter of the pinch. These measurements are used to gain a better understanding of Z-pinch equilibria.

  7. Broadening and shifting of the Raman Q branch of HD

    SciTech Connect

    Rosasco, G.J.; May, A.D.; Hurst, W.S.; Petway, L.B.; Smyth, K.C.

    1989-02-15

    The line broadening and shifting of the vibrational Q branch in pure HD has was measured for transitions J = 0 to 3 at room temperature over the density range 0.8 to 10.6 amagat. The shifting and broadening coefficients were determined with an uncertainty of + or - .0002/cm/amaget, which now provides a discriminating test for various semiclassical and quantal theoretical calculations. The line broadening coefficients are compared with linewidth data from other spectroscopic branches and with measurements of the rates of state-to-state rotational energy transfer. Use of an exponential gap law for the rates of rotational energy transfer allows estimates to be made of the contributions to the linewidths from rotationally inelastic, elastic vibrational dephasing, and elastic reorientation processes. This analysis suggests that rotational energy transfer occurs approximately 30% faster in v = 1 than in v = 0.

  8. Broadening and shifting of the Raman Q branch of HD

    SciTech Connect

    Rosasco, G.J.; May, A.D.; Hurst, W.S.; Petway, L.B.; Smyth, K.C.

    1989-02-15

    The line broadening and shifting of the vibrational Q branch in pure HD has been measured for transitions J = 0 to 3 at room temperature over the density range 0.8 to 10.6 amagat. The shifting and broadening coefficients have been determined with an uncertainty of +- 0.2 x 10/sup -3/ cm/sup -1/ /amagat, which now provides a discriminating test for various semiclassical and quantal theoretical calculations. The line broadening coefficients are compared with linewidth data from other spectroscopic branches and with measurements of the rates of state-to-state rotational energy transfer. Use of an exponential gap law for the rates of rotational energy transfer allows estimates to be made of the contributions to the linewidths from rotationally inelastic, elastic vibrational dephasing, and elastic reorientation processes. This analysis suggests that rotational energy transfer occurs approximately 30% faster in v = 1 than in v = 0.

  9. Longitudinal broadening of quenched jets in turbulent color fields.

    PubMed

    Majumder, A; Müller, B; Bass, S A

    2007-07-27

    The nearside distribution of particles at intermediate transverse momentum, associated with a high momentum trigger hadron produced in a high energy heavy-ion collision, is broadened in rapidity compared with the jet cone. This broadened distribution is thought to contain the energy lost by the progenitor parton of the trigger hadron. We show that the broadening can be explained as the final-state deflection of the gluons radiated from the hard parton inside the medium by soft, transversely oriented, turbulent color fields that arise in the presence of plasma instabilities. The magnitude of the effect is found to grow with medium size and density and diminish with increasing energy of the associated hadron.

  10. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking.

    PubMed

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J; Grillot, Frédéric

    2016-06-15

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%.

  11. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking

    PubMed Central

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J.; Grillot, Frédéric

    2016-01-01

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%. PMID:27302301

  12. Trace isotope detection enhanced by coherent elimination of power broadening.

    PubMed

    Conde, Alvaro Peralta; Brandt, Lukas; Halfmann, Thomas

    2006-12-15

    The selectivity and spectral resolution of traditional laser-based trace isotope analysis, i.e., resonance ionization mass spectrometry (RIMS), is limited by power broadening of the radiative transition. We use the fact that power broadening does not occur in coherently driven quantum systems when the probing and excitation processes are temporally separated to demonstrate significant improvement of trace element detection, even under conditions of strong signals. Specifically, we apply a coherent variant of RIMS to the detection of traces of molecular nitric oxide (NO) isobars. For large laser intensities, the detected isotope signal can be increased by almost 1 order of magnitude without any loss in spectral resolution.

  13. Combustion technology overview. [the use of broadened property aircraft fuels

    NASA Technical Reports Server (NTRS)

    Niedzwiecki, R. W.

    1980-01-01

    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.

  14. Trace Isotope Detection Enhanced by Coherent Elimination of Power Broadening

    SciTech Connect

    Conde, Alvaro Peralta; Brandt, Lukas; Halfmann, Thomas

    2006-12-15

    The selectivity and spectral resolution of traditional laser-based trace isotope analysis, i.e., resonance ionization mass spectrometry (RIMS), is limited by power broadening of the radiative transition. We use the fact that power broadening does not occur in coherently driven quantum systems when the probing and excitation processes are temporally separated to demonstrate significant improvement of trace element detection, even under conditions of strong signals. Specifically, we apply a coherent variant of RIMS to the detection of traces of molecular nitric oxide (NO) isobars. For large laser intensities, the detected isotope signal can be increased by almost 1 order of magnitude without any loss in spectral resolution.

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

    SciTech Connect

    Gray, Mark Girard

    2015-11-06

    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.

  16. On the Stark Broadening of Single Ionized Argon Lines

    NASA Astrophysics Data System (ADS)

    Dimitrijević, M. S.; Truong-Bach

    1986-06-01

    Using a semi-classical formalism which includes Debye shielding, Stark broadening parameters of various components within the 4 s 2P - 4 p ´ 2P0 multiplet and the 4 p - 4 d (2P 0 - 2P, 2D0 - 2 P, 2D0 - 2D) supermutiplet of Ar II are computed. We show that when various components of a multiplet (supermultiplet or transition array) are broadened inequally by an embedded closelying perturbing level, use of a perturber param eter cut-off at the Debye length can restrain the calculated differences between Stark widths within the multiplet.

  17. Laboratory Pressure Broadening Coefficients To Support SOIR/VEx And SOIR-NOMAD

    NASA Astrophysics Data System (ADS)

    Drummond, Rachel; Földes, T.; Vander Auwera, J.; Mahieux, A.; Robert, S.; Vandaele, A.; Wilquet, V.

    2010-10-01

    Precise spectroscopic data to describe CO2 pressure-broadened lineshapes of trace gases in the Venus and Mars atmospheres are rather scarce. In an attempt to compensate for such a situation, we recorded in the laboratory CO2 broadened absorption spectra of the 1-0 band of HCl near 2886 cm-1 and the ν3 band of CH4 near 3019 cm-1 at several pressures between 150 and 700 Torr, using a high-resolution Fourier transform spectrometer. CO2 pressure broadening half-width coefficients are extracted by least-squares fitting of suitable molecular line profiles, including instrumental effects. Sensitivity studies have been performed using the characteristics of the SOIR instrument. This instrument is currently on board the Venus Express mission (ESA) and has been proposed as payload for the future ExoMars 2016 TGO mission (ESA/NASA). The SOIR instrument is designed to measure atmospheric transmission in the near-IR (2.2 - 4.3 µm) at high resolution (0.12 cm-1) through solar occultation observations. It therefore allows the derivation of unique remote sensing information about the vertical structure and composition of the Venus mesosphere, with very good spatial resolution. At Venus, SOIR is able to provide HCl vertical profiles ranging typically from 80 to 105 km, at both morning and evening terminators, where the dynamics of the planetary atmosphere are relatively unknown. At Mars, the high resolution of the instrument will make it possible to observe CH4, if any. We show here how these two approaches, laboratory and space missions, are complimentary, as broadening coefficients measured in the laboratory allow us to simulate perfectly HCl and CH4 lines as seen by SOIR.

  18. Measurements of air-broadened and nitrogen-broadened half-widths and shifts of ozone lines near 9 microns

    NASA Technical Reports Server (NTRS)

    Smith, M. A. H.; Rinsland, C. P.; Devi, Malathy V.; Benner, D. Chris; Thakur, K. B.

    1988-01-01

    Air- and nitrogen-broadened half-widths and line shifts at room temperature for more than 60 individual vibration-rotation transitions in the nu1 fundamental band of (O-16)3 and several transitions in the nu3 band were determined from infrared absorption spectra. These spectra were recorded at 0.005/cm resolution with a Fourier-transform spectrometer. A tunable-diode-laser spectrometer operating in the 1090-1150/cm region was also used to record data on oxygen-, nitrogen-, and air-broadened half-widths for selected individual transitions. The nitrogen- and air-broadened half-widths determined by these two different measurement techniques are consistent to within 4 percent. The results are in good agreement with other published measurements and calculations.

  19. Measurements of air-broadened and nitrogen-broadened half-widths and shifts of ozone lines near 9 microns

    NASA Technical Reports Server (NTRS)

    Smith, M. A. H.; Rinsland, C. P.; Devi, Malathy V.; Benner, D. Chris; Thakur, K. B.

    1988-01-01

    Air- and nitrogen-broadened half-widths and line shifts at room temperature for more than 60 individual vibration-rotation transitions in the nu1 fundamental band of (O-16)3 and several transitions in the nu3 band were determined from infrared absorption spectra. These spectra were recorded at 0.005/cm resolution with a Fourier-transform spectrometer. A tunable-diode-laser spectrometer operating in the 1090-1150/cm region was also used to record data on oxygen-, nitrogen-, and air-broadened half-widths for selected individual transitions. The nitrogen- and air-broadened half-widths determined by these two different measurement techniques are consistent to within 4 percent. The results are in good agreement with other published measurements and calculations.

  20. Relational Themes in Counseling Supervision: Broadening and Narrowing Processes

    ERIC Educational Resources Information Center

    Gazzola, Nicola; Theriault, Anne

    2007-01-01

    This study investigated the experiences of broadening (i.e., thinking and acting creatively and being open to exploring new ways of being) and narrowing (i.e., the experience of perceiving one's choices as limited) in the supervisory process with the aim of identifying key relational themes from the perspective of supervisees. We interviewed 10…

  1. Critical tests of line broadening theories by precision measurements

    SciTech Connect

    Glenzer, S.H.

    1996-02-22

    The spectral line profiles of ionized emitters in plasmas play an important role in the calculation of opacity, for short-wavelength laser studies, and for the diagnostics of inertial confinement fusion plasmas. Sophisticated theoretical methods and modeling have been advanced and applied in recent years to calculate spectral line profiles in the limits where broadening by electron collisions or by ion microfield dominates. Here, the authors describe recent measurements of spectral line profiles of a z-pinch experiment employing precision plasma diagnostic techniques. In particular, the electron-collisional-broadened 2s--2p transitions in B{sub III} have been investigated because their line profiles provide an excellent test for electron-impact line shape theories and electron collision strength calculations. Although they find good agreement with semiclassical calculations, a factor of two discrepancy with the most elaborate quantum-mechanical five-state close coupling calculations is observed. They discuss the experimental error estimates of the various measured quantities and show that the observed discrepancy can not be explained by experimental shortcomings. They further discuss measurements of non-isolated spectral lines of some {Delta}n = 1 transitions in C{sub IV}--O{sub VI}. For these transitions ion broadening dominates. Excellent agreement for the whole line profile with line broadening calculations is obtained for all cases only when including ion dynamic effects. The latter are calculated using the frequency-fluctuation model and account for about 10--25% of the line width of the considered ions.

  2. Quality's Higher Education Dividends: Broadened Custodianship and Global Public Scholarship

    ERIC Educational Resources Information Center

    Jacobs, Gerrie J.

    2010-01-01

    This paper speculates on the possible contribution of the quality movement to higher education and the perceived dividends received from this, in general, over the past two decades but also, more specifically, with reference to the author's institution in South Africa. The first major quality contribution is a gradual broadening of higher…

  3. Broadening the Horizons: Organizational Communication in the Real World.

    ERIC Educational Resources Information Center

    Swanson, Georgia

    Working in the microcosm of an individual class, organizational communication instructors can broaden the student's horizon by starting with what are local types of diversity and then expanding the classroom understanding to include the larger world where that student is going to live and work. Speech communication teachers/scholars have seen…

  4. Community Colleges Broadening Horizons through Service Learning, 2006-2009

    ERIC Educational Resources Information Center

    Robinson, Gail

    2007-01-01

    This brief introduces "Community Colleges Broadening Horizons through Service Learning," the American Association of Community Colleges' (AACC's) fifth national Learn and Serve America grant project and describes its grantee college programs. The goals of this grant project are to build on established foundations to integrate service…

  5. Transboundary natural area protection: Broadening the definition of national security

    Treesearch

    Haven B. Cook

    2007-01-01

    This paper looks at the definition and concept of national security, and examines how the environment is linked with national security. The traditional, state view of national security that guides most foreign policy includes the concepts of military power, sovereignty and geopolitical stability. This paper advocates broadening the definition of security to include...

  6. The STARS Alliance: Viable Strategies for Broadening Participation in Computing

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  7. The STARS Alliance: Viable Strategies for Broadening Participation in Computing

    ERIC Educational Resources Information Center

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

    2011-01-01

    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. Coincidence doppler broadening study in electron-irradiated polyurethane

    NASA Astrophysics Data System (ADS)

    Yang, D. J.; Zhang, J. D.; Leung, J. K. C.; Beling, C. D.; Liu, L. B.

    2007-06-01

    Coincidence doppler broadening measurements on electron-irradiated polyurethanes were performed in the presence of air. It is shown that, after a certain electron irradiation, the momentum density distributions of annihilation electrons have obvious changes for the high crosslinking polyurethane, but no significant changes have been observed for the low crosslinking polyurethane. The results were performed to analyse by irradiation crosslinking and degradation principles.

  9. On-The-Fly Neutron Doppler Broadening in MCNP

    NASA Astrophysics Data System (ADS)

    Martin, William R.; Brown, Forrest B.; Wilderman, Scott; Yesilyurt, Gokhan

    2014-06-01

    Multi-physics calculations may involve coupling continuous-energy Monte Carlo neutronics codes to CFD codes that provide many thousands or even millions of region temperatures. The traditional Monte Carlo approach - using precalculated Doppler broadened nuclear cross-sections - is not feasible for these large multiphysics problems. Instead, an On-the-Fly (OTF) Doppler broadening methodology is required, whereby neutron cross-sections are broadened during the Monte Carlo transport. To this end, we have developed a methodology for MCNP to provide OTF broadening based on cell temperatures during neutron tracking. The method enables the use of many thousands or more temperatures in MCNP Monte Carlo calculations for multiphysics applications, significantly advancing the state-of-the-art by permitting the solution of problems that were not previously possible with continuous-energy Monte Carlo codes. A production library with an extended set of isotopes has been developed for use with MCNP6. Calculations of test problems with MCNP6 and the new library demonstrate the accuracy and effectiveness of the OTF approach.

  10. Phase dynamics in a Doppler broadened optically-pumped laser

    NASA Astrophysics Data System (ADS)

    Roldán, E.; de Valcárcel, G. J.; Vilaseca, R.; Silva, F.; Pujol, J.; Corbalán, R.; Laguarta, F.

    1989-11-01

    The dynamic behavior of the phase of the generated field in a Doppler-broadened optically-pumped far-infrared laser is theoretically investigated for the first time. The phase undergoes sudden jumps of approximately π radians, which allow to establish the actual symmetry of the main attractor in the phase space, explaining the heteroclynic character of the chaotic behavior observed in experiments.

  11. Broadening horizons: engaging advanced practice nursing students in faculty research.

    PubMed

    Weiss, Josie A

    2009-01-01

    Inviting advanced practice nursing students to participate in faculty research can be an innovative way to interest students in using current evidence as the basis for their practice. The author discusses strategies for effectively engaging graduate nursing students into research projects in ways that broaden the students' perspectives and strengthen their healthcare decision-making skills.

  12. Phenomenological plasmon broadening and relation to the dispersion

    NASA Astrophysics Data System (ADS)

    Hobbiger, Raphael; Drachta, Jürgen T.; Kreil, Dominik; Böhm, Helga M.

    2017-02-01

    Pragmatic ways of including lifetime broadening of collective modes in the electron liquid are critically compared. Special focus lies on the impact of the damping parameter onto the dispersion. It is quantitatively exemplified for the two-dimensional case, for both, the charge ('sheet'-)plasmon and the spin-density plasmon. The predicted deviations fall within the resolution limits of advanced techniques.

  13. Extending, Broadening and Rethinking Existing Research on Transfer of Training

    ERIC Educational Resources Information Center

    Volet, Simone

    2013-01-01

    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…

  14. ECRH microwave beam broadening in the edge turbulent plasma

    SciTech Connect

    Sysoeva, E. V.; Gusakov, E. Z.; Popov, A. Yu.; Silva, F. da; Heuraux, S.

    2014-02-12

    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.

  15. Electron Broadening of Isolated Lines with Stationary Non-Equilibrium Level Populations

    SciTech Connect

    Iglesias, C A

    2005-01-12

    It is shown that a quantum kinetic theory approach to line broadening, extended to stationary non-equilibrium states, yields corrections to the standard electron impact widths of isolated lines that depend on the population of the radiator internal levels. A consistent classical limit from a general quantum treatment of the perturbing electrons also introduces corrections to the isolated line widths. Both effects are essential in preserving detailed-balance relations. Preliminary analysis indicates that these corrections may resolve existing discrepancies between theoretical and experimental widths of isolated lines. An experimental test of the results is proposed.

  16. Hydrogen Balmer Line Broadening in Solar and Stellar Flares

    NASA Astrophysics Data System (ADS)

    Kowalski, Adam F.; Allred, Joel C.; Uitenbroek, Han; Tremblay, Pier-Emmanuel; Brown, Stephen; Carlsson, Mats; Osten, Rachel A.; Wisniewski, John P.; Hawley, Suzanne L.

    2017-03-01

    The broadening of the hydrogen lines during flares is thought to result from increased charge (electron, proton) density in the flare chromosphere. However, disagreements between theory and modeling prescriptions have precluded an accurate diagnostic of the degree of ionization and compression resulting from flare heating in the chromosphere. To resolve this issue, we have incorporated the unified theory of electric pressure broadening of the hydrogen lines into the non-LTE radiative-transfer code RH. This broadening prescription produces a much more realistic spectrum of the quiescent, A0 star Vega compared to the analytic approximations used as a damping parameter in the Voigt profiles. We test recent radiative-hydrodynamic (RHD) simulations of the atmospheric response to high nonthermal electron beam fluxes with the new broadening prescription and find that the Balmer lines are overbroadened at the densest times in the simulations. Adding many simultaneously heated and cooling model loops as a “multithread” model improves the agreement with the observations. We revisit the three-component phenomenological flare model of the YZ CMi Megaflare using recent and new RHD models. The evolution of the broadening, line flux ratios, and continuum flux ratios are well-reproduced by a multithread model with high-flux nonthermal electron beam heating, an extended decay phase model, and a “hot spot” atmosphere heated by an ultrarelativistic electron beam with reasonable filling factors: ∼0.1%, 1%, and 0.1% of the visible stellar hemisphere, respectively. The new modeling motivates future work to understand the origin of the extended gradual phase emission.

  17. Observation of Doppler broadening in β -delayed proton- γ decay

    DOE PAGES

    Schwartz, S. B.; Wrede, C.; Bennett, M. B.; ...

    2015-09-14

    Background: The Doppler broadening of gamma-ray peaks is 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 P-26(beta p gamma)Al-25 decay sequence. Methods: A fast beam of P-26 was implanted into a planar Ge detector, which was used as a P-26 beta-decay trigger. The SeGA array of high-purity Ge detectors was used to detect gamma rays frommore » the P-26(beta p gamma)Al-25 decay sequence. Results: Radiative Doppler broadening in beta-delayed proton-gamma decay was observed for the first time. Moreover, 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 Al-25 level was observed in P-26(beta p gamma)Al-25 decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is 5.1 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV, corresponding to a Si-26 excitation energy of 13.3 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV for the proton-emitting level. Conclusions: Finally, the Doppler broadening method has been demonstrated to provide practical measurements of the energies for beta-delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as A = 25.« less

  18. GOLD: Building capacity for broadening participation in the Geosciences

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    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

  19. A Global Fitting Approach For Doppler Broadening Thermometry

    NASA Astrophysics Data System (ADS)

    Amodio, Pasquale; Moretti, Luigi; De Vizia, Maria Domenica; Gianfrani, Livio

    2014-06-01

    Very recently, a spectroscopic determination of the Boltzmann constant, kB, has been performed at the Second University of Naples by means of a rather sophisticated implementation of Doppler Broadening Thermometry (DBT)1. Performed on a 18O-enriched water sample, at a wavelength of 1.39 µm, the experiment has provided a value for kB with a combined uncertainty of 24 parts over 106, which is the best result obtained so far, by using an optical method. In the spectral analysis procedure, the partially correlated speed-dependent hard-collision (pC-SDHC) model was adopted. The uncertainty budget has clearly revealed that the major contributions come from the statistical uncertainty (type A) and from the uncertainty associated to the line-shape model (type B)2. In the present work, we present the first results of a theoretical and numerical work aimed at reducing these uncertainty components. It is well known that molecular line shapes exhibit clear deviations from the time honoured Voigt profile. Even in the case of a well isolated spectral line, under the influence of binary collisions, in the Doppler regime, the shape can be quite complicated by the joint occurrence of velocity-change collisions and speed-dependent effects. The partially correlated speed-dependent Keilson-Storer profile (pC-SDKS) has been recently proposed as a very realistic model, capable of reproducing very accurately the absorption spectra for self-colliding water molecules, in the near infrared3. Unfortunately, the model is so complex that it cannot be implemented into a fitting routine for the analysis of experimental spectra. Therefore, we have developed a MATLAB code to simulate a variety of H218O spectra in thermodynamic conditions identical to the one of our DBT experiment, using the pC-SDKS model. The numerical calculations to determine such a profile have a very large computational cost, resulting from a very sophisticated iterative procedure. Hence, the numerically simulated spectra

  20. Finite beam-width ray model for geometric spectral broadening.

    PubMed

    Hoskins, P R; Fish, P J; Pye, S D; Anderson, T

    1999-03-01

    The purpose of the study was to compare measured spectral width and maximum frequency with that predicted from ray models of geometric spectral broadening. Zero and finite beam-width models were used. Spectral data were acquired from a string phantom using two commonly-used linear array systems. Beam width and Doppler aperture sizes were measured using a needle hydrophone. The results showed that the experimentally measured data agreed best with the finite beam-width model. The zero beam-width model was in error by up to 50% for calculated spectral width, and up to 10% for maximum frequency. It is concluded that spectral width and maximum frequency are best calculated using the finite beam-width model, and that ultrasound manufacturers could improve the variation in spectral broadening measured at different locations on a single machine by adjusting the aperture size to give a constant subtended angle and beam width.

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

    NASA Astrophysics Data System (ADS)

    Edmonds, Terrence; Li, Qingfeng; Wang, Fuqiang

    2017-10-01

    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 functions of the number of parton-parton collisions suffered by a high transverse momentum probe parton (Ncoll) and the azimuth of the probe relative to the reaction plane (ϕfin.probe). Correlation is found to broaden with increasing Ncoll and ϕfin.probe from in- to out-of-plane direction. This study provides a transport model reference for future jet-medium interaction studies.

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

    PubMed

    Schmied, Roland; Fowlkes, Jason D; Winkler, Robert; Rack, Phillip D; Plank, Harald

    2015-01-01

    The present study explores lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IV)Me3 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.

  3. Attention and positive affect: temporal switching or spatial broadening?

    PubMed

    Phaf, R Hans

    2015-04-01

    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.

  4. Positive emotions and the social broadening effects of Barack Obama.

    PubMed

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

    2012-10-01

    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.

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

    DOE PAGES

    Schmied, Roland; Fowlkes, Jason Davidson; Winkler, Robert; ...

    2015-01-01

    In this study, we explore lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IV)Me3 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. In addition, it is demonstrated that intermediate energies lead to evenmore » more complex proximity effects that significantly reduce lateral edge sharpness and thus should be avoided if desiring high lateral resolution.« less

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

    SciTech Connect

    Schmied, Roland; Fowlkes, Jason Davidson; Winkler, Robert; Rack, Phillip D.; Plank, Harald

    2015-01-01

    In this study, we explore lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IV)Me3 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. In addition, 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.

  7. Correction for inhomogeneous line broadening in spin labels, II

    NASA Astrophysics Data System (ADS)

    Bales, Barney L.

    Our methods to correct for inhomogeneous line broadening in the EPR of nitroxide spin labels are extended. Previously, knowledge of the hyperfine pattern of the nuclei responsible for the inhomogeneous broadening was necessary in order to carry out the corrections. This normally meant that either a separate NMR experiment or EPR spectral simulation was needed. Here a very simple method is developed, based upon measurement of four points on the experimental EPR spectrum itself, that allows one to carry out the correction procedure with precision rivaling that attained using NMR or spectral simulation. Two associated problems are solved: (1) the EPR signal strength is estimated without the need to carry out double integrations and (2) linewidth ratios, important in calculating rotational correlation times, are corrected. In all cases except one, the corrections are effected from the four measured points using only a hand-held programmable calculator. Experimental examples illustrate the methods and show them to be amazingly accurate.

  8. Inhomogeneous broadening effects in multimode CW chemical lasers

    NASA Astrophysics Data System (ADS)

    Mirels, H.

    1981-01-01

    The performance of a multiple longitudinal mode CW chemical laser is investigated with reference to the effects of inhomogeneous broadening for the case where the longitudinal mode spacing is small compared with the characteristic Doppler and homogeneous widths of the lasing medium. Both a Fabry-Perot resonator and a saturated amplifier are considered, using a two-vibrational-level model. Closed form solutions are obtained which are shown to be in good agreement with the numerical results of Bullock and Lipkis (1979).

  9. Hydrogen Stark broadening by different kinds of model microfields

    NASA Astrophysics Data System (ADS)

    Seidel, J.

    1980-07-01

    A new model microfield is defined (the theta process) which in conjunction with the kangaroo process, is used to demonstrate the effects of different model microfields on hydrogen line profiles. The differences in the statistical features of the models give an estimate of the uncertainties associated with the method of model microfields. Stark broadening of hydrogen Lyman lines by either electrons or ions is investigated specifically.

  10. Tunable Optical Delay in Doppler-Broadened Cesium Vapor

    DTIC Science & Technology

    2010-12-01

    optical buffer system. Alkali - metal elements offer well-documented relatively simple atomic systems with physical properties , such as large vapor...Kramers-Kronig delay model is developed using complete hyperfine structure treatment with Voigt profile lineshapes in a Doppler-broadened alkali - metal ... alkali -laser is a gas-phase three-level laser using the ground state (S1/2) and the first two excited states (P1/2 and P3/2) of the alkali - metal vapor

  11. Spectral broadening of interacting pigments: polarized absorption by photosynthetic proteins.

    PubMed

    Somsen, O J; van Grondelle, R; van Amerongen, H

    1996-10-01

    Excitonic interaction between pigment molecules is largely responsible for the static and dynamic spectroscopic properties of photosynthetic pigment-proteins. This paper provides a new description of its effect on polarized absorption spectroscopy, in particular on circular dichroism (CD). We investigate excitonic spectra of finite width and use "spectral moments" to compare 1) inhomogeneously broadened excitonic spectra, 2) spectra that are (homogeneously broadened by vibrations or electron-phonon interaction, and 3) spectra that are simulated by applying convolution after the interaction has been evaluated. Two cases are distinguished. If the excitonic splitting is smaller than the width of the interacting absorption bands, the broadening of the excitonic spectrum can be approximated by a convolution approach, although a correction is necessary for CD spectra. If the excitonic splitting exceeds the bandwidth, the well-known exchange narrowing occurs. We demonstrate that this is accompanied by redistribution of dipole strength and spectral shifts. The magnitude of a CD spectrum is conveniently expressed by its first spectral moment. As will be shown, this is independent of spectral broadening as well as dispersive shifts induced by pigment-protein interactions. Consequently, it provides a simple tool to relate the experimental CD spectrum of a pigment complex to the excitonic interactions from which it originates. To illustrate the potential of the presented framework, the spectroscopy of the LH2 pigment-protein complex from purple bacteria is analyzed and compared for dimer-like and ring-like structures. Furthermore, it is demonstrated that the variability of the CD of chlorosomes from green bacteria can be explained by small changes in the structure of their cylindrical bacteriochlorophyll c subunits.

  12. Spectral broadening of interacting pigments: polarized absorption by photosynthetic proteins.

    PubMed Central

    Somsen, O J; van Grondelle, R; van Amerongen, H

    1996-01-01

    Excitonic interaction between pigment molecules is largely responsible for the static and dynamic spectroscopic properties of photosynthetic pigment-proteins. This paper provides a new description of its effect on polarized absorption spectroscopy, in particular on circular dichroism (CD). We investigate excitonic spectra of finite width and use "spectral moments" to compare 1) inhomogeneously broadened excitonic spectra, 2) spectra that are (homogeneously broadened by vibrations or electron-phonon interaction, and 3) spectra that are simulated by applying convolution after the interaction has been evaluated. Two cases are distinguished. If the excitonic splitting is smaller than the width of the interacting absorption bands, the broadening of the excitonic spectrum can be approximated by a convolution approach, although a correction is necessary for CD spectra. If the excitonic splitting exceeds the bandwidth, the well-known exchange narrowing occurs. We demonstrate that this is accompanied by redistribution of dipole strength and spectral shifts. The magnitude of a CD spectrum is conveniently expressed by its first spectral moment. As will be shown, this is independent of spectral broadening as well as dispersive shifts induced by pigment-protein interactions. Consequently, it provides a simple tool to relate the experimental CD spectrum of a pigment complex to the excitonic interactions from which it originates. To illustrate the potential of the presented framework, the spectroscopy of the LH2 pigment-protein complex from purple bacteria is analyzed and compared for dimer-like and ring-like structures. Furthermore, it is demonstrated that the variability of the CD of chlorosomes from green bacteria can be explained by small changes in the structure of their cylindrical bacteriochlorophyll c subunits. Images FIGURE 3 FIGURE 4 PMID:8889168

  13. The Effects of Career Broadening on Leadership Development

    DTIC Science & Technology

    2007-03-01

    commander 6.6 11FX USAF Air Demonstration Pilot ( Thunderbirds ) 6.1 21XX Logistics Career Broadening Program 5.1 XXXX Re-Trained into another AFSC 3.9 XXXX...boards in 2004 and 2005, as well as, those officers who competed for selection to in-residence PME programs at the intermediate and senior development...development programs in which leaders will have to develop higher level leadership skills, develop new leadership competencies and refine old competencies

  14. Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS

    NASA Astrophysics Data System (ADS)

    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.

    2017-02-01

    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.

  15. Temperature Dependence of Stark Broadening Dominated by Strong Collisions

    SciTech Connect

    Gigosos, M. A.; Gonzalez, M. A.; Konjevic, N.

    2006-11-22

    The influence of electron temperature in the broadening of spectral lines dominated by strong collisions has been studied. Computer simulation allows us to study the effects of strong and weak collisions separately. Results shown here are focused on some Sr+ and Ba+ resonance lines as examples of lines broadened dominantly by strong collisions. The exact numerical integration of the perturbation process due to the collision with a single particle permits the evaluation of Weisskopf radius. This parameter is usually defined as rw {approx} 1/v {approx} 1/{radical}T, obtained from Bora approximation that is correct for high temperatures. However, at low temperatures the full integration of the collision process permits to test the relationship rw {approx} 1/T1/6. This calculation has allowed us to study the influence of temperature on the broadening of the lines dominated by strong collisions. This study has been done in two ways : through a plasma simulation and analyzing the calculated Weisskopf radius for an individual collision. The obtained results show that at low temperatures the width of the line increases for increasing temperature as a consequence of an increase of the number of collisions not compensated by the decrease of Weisskopf radius.

  16. Experimental Measurement of ECH Deposition Broadening: Beyond Anomalous Transport

    NASA Astrophysics Data System (ADS)

    Brookman, M. W.; Austin, M. E.; Gentle, K. W.; Petty, C. C.; Ernst, D. E.; Peysson, Y.; Decker, J.; Barada, K.

    2017-07-01

    This work provides a first experimental measurement of broadened ECH deposition on the DIIID tokamak. As seen in theory[1] and simulation[2], refraction by edge density fluctuations shifts the path of RF waves, altering ECH and ECCD deposition. This paper reports on an initial experimental confirmation of broadened ECH deposition on DIII-D tokamak. Te measurements from a 48 channel 2nd Harmonic ECE Radiometer digitized at 500 kHz are used with a set of broadened trial ECH deposition functions to calculate time-dependent, modulation-induced heat fluxes. The fitting of convective and diffusive transport to these fluxes allows different ECH deposition profiles to be compared. The best-fit ECH deposition produces reasonable transport coefficients which compare favorably with simulation. This method is applied to a set of L- and H- mode DIII-D discharges. Accounting for diffusive, convective, and coupled transport, the ECH deposition profile is found to be 2 to 3 times wider than predicted by TORAY-GA ray tracing.

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

    NASA Astrophysics Data System (ADS)

    Wolff, C.; Van Laer, R.; Steel, M. J.; Eggleton, B. J.; Poulton, C. G.

    2016-02-01

    We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the width and shape of the stimulated Brillouin scattering (SBS) resonance 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. Finally, we illustrate in a numerical example that in backward SBS and inter-mode forward SBS the existence of two broadening mechanisms with opposite sign also opens the possibility to compensate the effect of geometry-induced broadening. Our results can be transferred to other micro- and nano-structured waveguide geometries such as photonic crystal fibres.

  18. An Experimental and Theoretical Study of Nitrogen-Broadened Acetylene Lines

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    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.

  19. Modeling Solvent Broadening on the Vibronic Spectra of a Series of Coumarin Dyes. From Implicit to Explicit Solvent Models.

    PubMed

    Cerezo, Javier; Avila Ferrer, Francisco J; Prampolini, Giacomo; Santoro, Fabrizio

    2015-12-08

    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

  20. N 2- and O 2-broadening coefficients of C 2H 2 IR lines

    NASA Astrophysics Data System (ADS)

    Bouanich, J. P.; Lambot, D.; Blanquet, G.; Walrand, J.

    1990-04-01

    Pressure-broadening parameters of six lines belonging to the ν5 band of C 2H 2 in collision with N 2 have been measured with a tunable diode-laser spectrometer in order to complete up to J = 33 our earlier measurements (D. Lambot, G. Blanquet, and J. P. Bouanich, J. Mol. Spectrosc.136, 86-92 (1989)) on the broadening of C 2H 2 by N 2 and O 2 at 297 K. These N 2- and O 2-broadening coefficients have been first calculated on the basis of the Anderson-Tsao-Curnutte theory; in this approach, we show that the short-range interactions which contribute significantly to the linewidths are not correctly treated. Next, we consider the improved semiclassical model proposed by Robert and Bonamy. The intermolecular potential consists in the addition of the atom-atom interaction model to the quadrupolar interactions. The limited radial spherical harmonics expansion of the atom-atom potential, from which expressions for the differential cross section were derived, appears to be quite insufficient at short intermolecular distances. Therefore, we use a more accurate representation of this potential, avoiding an inadequate truncation and keeping the analytic expressions obtained by Bonamy and Robert. In the calculations we take into account the contributions derived from the radial functions U000( r), U200( r), and U220( r), as well as from U400( r). A theoretical expression is obtained for the U400 contribution to the differential cross section. The results of the calculations arising from the exact radial expansion of the atom-atom potential appear to be significantly larger for high J lines than those arising from the truncated expansion. The latter results, which do not include adjustable atom-atom parameters, are in good agreement with experimental broadening coefficients for C 2H 2O 2 and in reasonable agreement (except at large J values) for C 2H 2N 2. It is also shown that the contributions to the linewidths derived from U400 are rather small for C 2H 2N 2 and more

  1. Commercial observation satellites: broadening the sources of geospatial data

    NASA Astrophysics Data System (ADS)

    Baker, John C.; O'Connell, Kevin M.; Venzor, Jose A.

    2002-09-01

    Commercial observation satellites promise to broaden substantially the sources of imagery data available to potential users of geospatial data and related information products. We examine the new trend toward private firms acquiring and operating high-resolution imagery satellites. These commercial observation satellites build on the substantial experience in Earth observation operations provided by government-owned imaging satellites for civilian and military purposes. However, commercial satellites will require governments and companies to reconcile public and private interests in allowing broad public access to high-resolution satellite imagery data without creating national security risks or placing the private firms at a disadvantage compared with other providers of geospatial data.

  2. Infrared absorption cross sections of propane broadened by hydrogen

    NASA Astrophysics Data System (ADS)

    Wong, A.; Hargreaves, R. J.; Billinghurst, B.; Bernath, P. F.

    2017-09-01

    Fourier transform infrared absorption cross-sections of pure propane (C3H8) and propane broadened with H2 have been calculated from transmittance spectra recorded at temperatures from 292 K to 205 K. Transmittance spectra were recorded at the Canadian Light Source (CLS) Far-Infrared beamline, utilizing both the synchrotron source and the internal glowbar source. The absorption cross-sections have been calibrated to Pacific Northwest National Laboratory (PNNL) reference cross-sections of propane and can be used to interpret astronomical observations of giant planets such as Jupiter and Saturn as well as exoplanets.

  3. Theory of Moessbauer line broadening due to diffusion

    SciTech Connect

    Schroeder, K.; Wolf, D.; Dederichs, P.H.

    1981-12-01

    We have calculated the line broadening of the Moessbauer line due to diffusion of Moessbauer atoms via single vacanices. We take into account the perturbation of vacancy jumps in the neighbourhood of an impurity Moessbauer atom (e.g. Fe in Al) using the 5-frequency model. The anisotropy of the line width is given by the Fourier transform of the final distribution of a Moessbauer atom after an encounter with a vacancy. This distribution is calculated by Monte Carlo computer simulation. 3 figures, 1 tables.

  4. Stark broadening of hydrogen lines in magnetic fusion plasmas

    NASA Astrophysics Data System (ADS)

    Rosato, J.; Godbert-Mouret, L.; Koubiti, M.; Marandet, Y.; Stamm, R.

    2017-03-01

    We report on a Stark line shape model for the diagnostic of tokamak edge plasmas. In specific scenarios, plasma discharges are carried out at high density regimes, sufficiently so that the spectral lines emitted by the neutral atoms present in the edge and in the divertor region are affected by the plasma microscopic electric field (Stark broadening). We present new line shape calculations, carried out for diagnostic purposes in the context of the MST1 (Medium Sized Tokamak) European campaign. The role of the magnetic field (Zeeman effect) on line spectra is discussed.

  5. Strategies for broadening public involvement in space developments

    NASA Technical Reports Server (NTRS)

    Harris, Philip R.

    1992-01-01

    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.

  6. Anomalous excitation facilitation in inhomogeneously broadened Rydberg gases

    NASA Astrophysics Data System (ADS)

    Letscher, F.; Thomas, O.; Niederprüm, T.; Ott, H.; Fleischhauer, M.

    2017-02-01

    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 antiblockade. 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.

  7. Curves of growth for van der Waals broadened spectral lines

    NASA Technical Reports Server (NTRS)

    Park, C.

    1980-01-01

    Curves of growth are evaluated for a spectral line broadened by the van der Waals interactions during collisions. The growth of the equivalent widths of such lines is shown to be dependent on the product of the perturber density and the 6/10 power of the van der Waals potential coefficient. When the parameter is small, the widths grow as the 1/2 power of the optical depth as they do for the Voigt profile: but when the parameter is large, they grow as 2/3 power and, hence, faster than the Voigt profile. An approximate analytical expression for the computed growth characteristics is given.

  8. Broadening sources of Diginity and Affirmation in Work and Relationship

    PubMed Central

    Byars-Winston, Angela

    2012-01-01

    This article builds on assertions in Richardson’s (2012, this issue) Major Contribution on counseling for work and relationship. In this reaction, I expand on the relevance and potential of the counseling for work and relationship perspective to enrich the field of counseling psychology. My comments focus on three considerations to further extend the cultural relevance of Richardson’s work and relationship perspective: (1) broadening sources of dignity, (2) centering knowledge of marginalized communities, and (3) promoting psychologists’ critical consciousness. Richardson’s perspective holds great promise for being a guiding heuristic to inform counseling psychology research, theory, and practice. PMID:22563131

  9. Numerical computation of doppler-broadening in the resonance domain

    SciTech Connect

    Sanchez, R.

    2013-07-01

    We have implemented an accurate and fast calculation of the Doppler-broadened kernel PT(E {yields} E') for neutron elastic scattering based on a gas model. An exponential cutoff which accounts for the asymptotic behavior of the error function helps limit the range of integration while eliminating difference effects. This allows for calculating a kernel library for {sup 238}U over a very fine energy grid covering the resonance range in only a few hours in a laptop. We give an example showing the impact of {sup 238}U elastic up-scattering on the values of self shielded cross sections. (authors)

  10. The IACOB project . III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars

    NASA Astrophysics Data System (ADS)

    Simón-Díaz, S.; Godart, M.; Castro, N.; Herrero, A.; Aerts, C.; Puls, J.; Telting, J.; Grassitelli, L.

    2017-01-01

    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

  11. Effects of inhomogeneous broadening on the resonance Raman excitation profile of lycopene

    NASA Astrophysics Data System (ADS)

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

    1982-08-01

    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.

  12. Quantum-state storage and processing for polarization qubits in an inhomogeneously broadened {Lambda}-type three-level medium

    SciTech Connect

    Viscor, D.; Ferraro, A.; Mompart, J.; Ahufinger, V.; Loiko, Yu.

    2011-10-15

    We address the propagation of a single-photon pulse with two polarization components, i.e., a polarization qubit, in an inhomogeneously broadened ''phaseonium''{Lambda}-type three-level medium. We combine some of the nontrivial propagation effects characteristic for this kind of coherently prepared systems and the controlled reversible inhomogeneous broadening technique to propose several quantum information-processing applications, such as a protocol for polarization qubit filtering and sieving as well as a tunable polarization beam splitter. Moreover, we show that by imposing a spatial variation of the atomic coherence phase, an efficient quantum memory for the incident polarization qubit can be also implemented in {Lambda}-type three-level systems.

  13. Positive mood broadens visual attention to positive stimuli

    PubMed Central

    Wadlinger, Heather A.; Isaacowitz, Derek M.

    2010-01-01

    In an attempt to investigate the impact of positive emotions on visual attention within the context of Fredrickson's (1998) broaden-and-build model, eye tracking was used in two studies to measure visual attentional preferences of college students (n=58, n=26) to emotional pictures. Half of each sample experienced induced positive mood immediately before viewing slides of three similarly-valenced images, in varying central-peripheral arrays. Attentional breadth was determined by measuring the percentage viewing time to peripheral images as well as by the number of visual saccades participants made per slide. Consistent with Fredrickson's theory, the first study showed that individuals induced into positive mood fixated more on peripheral stimuli than did control participants; however, this only held true for highly-valenced positive stimuli. Participants under induced positive mood also made more frequent saccades for slides of neutral and positive valence. A second study showed that these effects were not simply due to differences in emotional arousal between stimuli. Selective attentional broadening to positive stimuli may act both to facilitate later building of resources as well as to maintain current positive affective states. PMID:20431711

  14. Momentum broadening in unstable quark-gluon plasma

    DOE PAGES

    Carrington, M. E.; Mrówczyński, St.; Schenke, B.

    2017-02-01

    We present that 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 parametermore » $$ˆ\\atop{q}$$ which determines the radiative energy loss of the test parton. We develop a formalism which gives $$ˆ\\atop{q}$$ 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 $$ˆ\\atop{q}$$ is found to be strongly dependent on time. For short times it is of the order of the equilibrium value, but at later times $$ˆ\\atop{q}$$ grows exponentially due to the interaction of the test parton with unstable modes and becomes much bigger than the value in equilibrium. The momentum broadening is also strongly directionally dependent and is largest when the test parton velocity is transverse to the beam axis. Lastly, consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.« less

  15. Stark Broadening Parameters For White Dwarf Atmospheres Research

    NASA Astrophysics Data System (ADS)

    Larbi-Terzi, N.; Sahal-Brechot, S.; Nessib, N. B.; Dimitrijevic, M. S.

    2010-07-01

    Stark broadening parameters of C II lines were determined within 3d-nf series using semiclassical perturbation method. The atomic energy levels needed for calculations were taken from TOPBASE as well as the oscillator strengths, which were additionally calculated using the method of Bates and Damgaard. The both results were compared and only insignificant differences were found. Calculations were performed for plasma conditions relevant for atmospheres of DQ white dwarfs and for a new type of white dwarfs, with surface composed mostly of carbon, discovered in 2007 by Dufour et al. The aim of this work is to provide accurate C II Stark broadening data, which are crucial for this type of white dwarf atmosphere modellisation. Obtained results will be included in STARK-B database (http://stark-b.obspm.fr/), entering in the FP7 project of European Virtual Atomic and Molecular Data Center VAMDC aiming at building an interoperable e- Infrastructure for the exchange of atomic and molecular data (http://www.vamdc.org/).

  16. Non-thermal line-broadening in solar prominences

    NASA Astrophysics Data System (ADS)

    Stellmacher, G.; Wiehr, E.

    2015-09-01

    Aims: We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities. Methods: 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. Results: We find a ratio of reduced widths, ΔλD/λ0, of Hγ and Hδ of 1.05 ± 0.03, which can hardly be attributed to saturation, since both are optically thin for the prominences observed: τγ ≤ 0.3, τδ ≤ 0.15. We confirm the ratio of reduced widths of He 4772 (triplet) and He 5015 (singlet) of 1.1 ± 0.05 at higher significance and detect a width ratio of Mg b2 and Mg 4571 (both from the triplet system) of 1.3 ± 0.1. Conclusions: The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [Tkin; Vnth]. Values of Tkin deduced from observed line radiances using models indicate low temperatures down to Tkin ≈ 5000 K. Non-thermal velocities, related to different physical states of the respective emitting prominence region, seem to be the most important line broadening mechanism.

  17. Rotational relaxation contributions to infrared pressure broadening in ozone

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  18. Momentum broadening in unstable quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Carrington, M. E.; Mrówczyński, St.; Schenke, B.

    2017-02-01

    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 q ̂ which determines the radiative energy loss of the test parton. We develop a formalism which gives 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 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 q ̂ grows exponentially due to the interaction of the test parton with unstable modes and becomes much bigger than the value in equilibrium. The momentum broadening is also strongly directionally dependent and is largest when the test parton velocity is transverse to the beam axis. Consequences of our findings for the phenomenology of jet quenching in relativistic heavy-ion collisions are briefly discussed.

  19. Multi-frequency Scatter Broadening Evolution of Pulsars. I

    NASA Astrophysics Data System (ADS)

    Krishnakumar, M. A.; Joshi, Bhal Chandra; Manoharan, P. K.

    2017-09-01

    We present multi-wavelength scatter broadening observations of 47 pulsars made with the Giant Metre-wave Radio Telescope (GMRT), Ooty Radio Telescope (ORT), and Long Wavelength Array (LWA). The GMRT observations were made in the phased array mode at 148, 234, and 610 MHz and the ORT observations at 327 MHz. The LWA data sets were obtained from the LWA pulsar data archive. The broadening of each pulsar as a function of observing frequency provides the frequency scaling index, α. The estimations of α have been obtained for 39 pulsars and include entirely new estimates for 31 pulsars. This study increases the total sample of pulsars available with α estimates by ∼50%. The overall distribution of α with the dispersion measure (DM) of the pulsar shows interesting variations, which are consistent with earlier studies. However, for a given value of DM, a range of α values are observed, indicating the characteristic turbulence along each line of sight. For each pulsar, the estimated level of turbulence, {C}{n{{e}}}2, has also been compared with α and DM. Additionally, we compare the distribution of α with the theoretically predicted model to infer the general characteristics of the ionized interstellar medium. Nearly 65% of the pulsars show a flatter index (i.e., α < 4.4) than that expected from the Kolmogorov turbulence model. Moreover, the group of pulsars with flatter indices is typically associated with an enhanced value of {C}{n{{e}}}2 compared to those with steeper indices.

  20. Encoding details: positive emotion leads to memory broadening.

    PubMed

    Yegiyan, Narine S; Yonelinas, Andrew P

    2011-11-01

    In the current experiment we tested the hypothesis that unlike negative arousal, which leads to memory narrowing effects whereby an increase in memory for the central details is accompanied by a decrease in memory for the peripheral details, positive arousing events might lead to a memory broadening effect such that positive arousal would increase memory for both central and peripheral details. This was assessed by testing recognition for central and peripheral details of pictures that were selected to vary in a continuous manner across a wide range of arousal for both positive and negative items. The results indicated that increases in both positive and negative stimulus arousal levels led to gradual increases in memory for the central aspects of the photos. In contrast, negative arousal first increased then decreased memory for peripheral detail as arousal levels increased, whereas positive arousal led to a continuous increase in memory for peripheral details. Thus, arousing negative materials lead to memory narrowing, whereas arousing positive materials can lead to memory broadening.

  1. Improving Program Design and Assessment with Broadening Participation Resources

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  2. Rotational relaxation contributions to infrared pressure broadening in ozone

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  3. Technical note: improved implementation of Doppler broadening in MCNP5.

    PubMed

    Bartol, Laura J; DeWerd, Larry A

    2012-09-01

    Incoherent scattering has a substantial effect on spectroscopic measurements and simulations. Many general-purpose Monte Carlo codes include models that account for the effects of bound electrons on incoherent scattering, including Doppler broadening (DB). This work investigates the DB model used in the Monte Carlo N-particle transport code (MCNP5). Simulations were run with three versions of MCNP5: v1.51, v1.60, and a modified form of v1.60 (v1.60m). All simulations used the MCPLIB04 photon data library, which presents the electron subshell data for incoherent scattering in the form of a probability density function. In v1.60m, the source code was altered to sample the electron subshell from a cumulative density function instead. Each version of the code was tested using an identical set of simulations that investigated DB in a slab of silicon at scattering angles of 15°, 30°, and 45°. For each angle, simulations were run for multiple energies between 200 keV and 800 keV. The spectrum of singly-scattered photons at the exit of the slab was scored. Spectra were analytically calculated for comparison. In v1.51, DB was modeled for incident photon energies below 760 keV, 384 keV, and 260 keV at scattering angles of 15°, 30°, and 45°, respectively. Above these energy thresholds, v1.51 did not model DB. The spectra calculated using v1.60 and v1.60m exhibited DB for all energy-angle combinations; however, v1.60m, exhibited more energy broadening than did v1.60. The spectra calculated with v1.60m agreed with the analytical calculations. MCNP5 v1.51 and v1.60 model partial broadening when used with the MCPLIB04 data library. MCNP5 v1.60m models DB more accurately due to the form of the electron subshell data. In response to these results, Los Alamos National Laboratory has released a new photon data library, MCPLIB84, that presents the electron subshell data in cumulative distribution form. MCNP5 v1.60 should be used with this library when incoherent scattering has a

  4. Strain broadening of the 1042-nm zero phonon line of the NV- center in diamond: A promising spectroscopic tool for defect tomography

    NASA Astrophysics Data System (ADS)

    Biktagirov, T. B.; Smirnov, A. N.; Davydov, V. Yu.; Doherty, M. W.; Alkauskas, A.; Gibson, B. C.; Soltamov, V. A.

    2017-08-01

    The negatively charged nitrogen-vacancy (NV-) center in diamond is a promising candidate for many quantum applications. Here, we examine the splitting and broadening of the center's infrared (IR) zero-phonon line (ZPL). We develop a model for these effects that accounts for the strain induced by photodependent microscopic distributions of defects. We apply this model to interpret observed variations of the IR ZPL shape with temperature and photoexcitation conditions. We identify an anomalous temperature-dependent broadening mechanism and that defects other than the substitutional nitrogen center significantly contribute to strain broadening. The former conclusion suggests the presence of a strong Jahn-Teller effect in the center's singlet levels and the latter indicates that major sources of broadening are yet to be identified. These conclusions have important implications for the understanding of the center and the engineering of diamond quantum devices. Finally, we propose that, once the major sources of broadening are identified, the IR ZPL has the potential to be a sensitive spectroscopic tool for probing microscopic strain fields and performing defect tomography.

  5. Calculation of pressure-broadened linewidths for CO in Ar

    NASA Technical Reports Server (NTRS)

    Green, S.

    1985-01-01

    Calculations of the pressure-broadening cross sections of CO in Ar have been made within the infinite-order sudden (IOS) and coupled states (CS) quantum scattering approximations. Two intermolecular potentials were used, a pairwise additive atom-atom potential which has been employed previously in semiclassical (modified Anderson theory) studies of this system and one calculated ab initio within an electron gas formalism. Predictions from the two potentials generally agree within about 25 percent and bracket experimental values (except for some recent high temperature data obtained in shock tube experiments). The CS approximation appears to be quite accurate although computationally expensive. The much cheaper IOS approximation is accurate for the J = 0-1 line but does not properly predict the dependence on line number. The quantum results are also compared with earlier semiclassical values.

  6. Scatter Broadening Measurements of 124 Pulsars At 327 Mhz

    NASA Astrophysics Data System (ADS)

    Krishnakumar, M. A.; Mitra, D.; Naidu, A.; Joshi, B. C.; Manoharan, P. K.

    2015-05-01

    We present the measurements of scatter broadening timescales ({{τ }sc}) for 124 pulsars at 327 MHz using the upgraded Ooty Radio Telescope. These pulsars lie in the dispersion measure range of 37-503 pc cm-3 and declination (δ) range of -57°\\lt δ \\lt 60{}^\\circ . New {{τ }sc} estimates for 58 pulsars are presented, increasing the sample of all such measurements by about 40% at 327 MHz. Using all available {{τ }sc} measurements in the literature, we investigate the dependence of {{τ }sc} on dispersion measure. Our measurements, together with previously reported values for {{τ }sc}, affirm that the ionized interstellar medium up to 3 kpc is consistent with the Kolmogorov spectrum, while it deviates significantly beyond this distance.

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

    PubMed

    Arslan, Betül K; Boyd, Eric S; Dolci, Wendy W; Dodson, K Estelle; Boldt, Marco S; Pilcher, Carl B

    2011-08-01

    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.

  8. Broadening the interface bandwidth in simulation based training

    NASA Technical Reports Server (NTRS)

    Somers, Larry E.

    1989-01-01

    Currently most computer based simulations rely exclusively on computer generated graphics to create the simulation. When training is involved, the method almost exclusively used to display information to the learner is text displayed on the cathode ray tube. MICROEXPERT Systems is concentrating on broadening the communications bandwidth between the computer and user by employing a novel approach to video image storage combined with sound and voice output. An expert system is used to combine and control the presentation of analog video, sound, and voice output with computer based graphics and text. Researchers are currently involved in the development of several graphics based user interfaces for NASA, the U.S. Army, and the U.S. Navy. Here, the focus is on the human factors considerations, software modules, and hardware components being used to develop these interfaces.

  9. Standard line broadening impact theory for hydrogen including penetrating collisions

    NASA Astrophysics Data System (ADS)

    Alexiou, S.; Poquérusse, A.

    2005-10-01

    In recent years there has been significant interest in the emission spectra from high-density plasmas, as manifested by a number of experiments. At these high densities short range (small impact parameter) interactions become important and these cannot be adequately handled by the standard theory, whose predictions depend on some cutoffs, necessary to preserve unitarity, the long range approximation, and to ensure the validity of a semiclassical picture. Very recently, as a result of a debate concerning the broadening of isolated ion lines, the importance of penetration of bound electron wave functions by plasma electrons has been realized. By softening the interaction, penetration makes perturbative treatments more valid. The penetration effect has now been included analytically into the standard theory. It turns out that the integrations may be done in closed form in terms of the modified Bessel functions K0 and K1 . This work develops the new theory and applies it to experimental measurements.

  10. Comparing the line broadened quasilinear model to Vlasov code

    SciTech Connect

    Ghantous, K.; Berk, H. L.; Gorelenkov, N. N.

    2014-03-15

    The Line Broadened Quasilinear (LBQ) model is revisited to study its predicted saturation level as compared with predictions of a Vlasov solver BOT [Lilley et al., Phys. Rev. Lett. 102, 195003 (2009) and M. Lilley, BOT Manual. The parametric dependencies of the model are modified to achieve more accuracy compared to the results of the Vlasov solver both in regards to a mode amplitude's time evolution to a saturated state and its final steady state amplitude in the parameter space of the model's applicability. However, the regions of stability as predicted by LBQ model and BOT are found to significantly differ from each other. The solutions of the BOT simulations are found to have a larger region of instability than the LBQ simulations.

  11. Photosynthetic innovation broadens the niche within a single species.

    PubMed

    Lundgren, Marjorie R; Besnard, Guillaume; Ripley, Brad S; Lehmann, Caroline E R; Chatelet, David S; Kynast, Ralf G; Namaganda, Mary; Vorontsova, Maria S; Hall, Russell C; Elia, John; Osborne, Colin P; Christin, Pascal-Antoine

    2015-10-01

    Adaptation to changing environments often requires novel traits, but how such traits directly affect the ecological niche remains poorly understood. Multiple plant lineages have evolved C4 photosynthesis, a combination of anatomical and biochemical novelties predicted to increase productivity in warm and arid conditions. Here, we infer the dispersal history across geographical and environmental space in the only known species with both C4 and non-C4 genotypes, the grass Alloteropsis semialata. While non-C4 individuals remained confined to a limited geographic area and restricted ecological conditions, C4 individuals dispersed across three continents and into an expanded range of environments, encompassing the ancestral one. This first intraspecific investigation of C4 evolutionary ecology shows that, in otherwise similar plants, C4 photosynthesis does not shift the ecological niche, but broadens it, allowing dispersal into diverse conditions and over long distances. Over macroevolutionary timescales, this immediate effect can be blurred by subsequent specialisation towards more extreme niches.

  12. Investigation of the Stark broadening of Balmer beta

    NASA Astrophysics Data System (ADS)

    Helbig, V.; Nick, K.-P.

    1981-10-01

    The Stark broadening of the Balmer line Hβ was studied in a high-current wall-stabilized arc at electron densities between 1.75 and 14.4 × 1016 cm-3. The electron density was obtained by means of a two-wavelength Michelson interferometer. The reduced half-widths of Hβ were compared with the theories of Griem et al, Vidal et al and Seidel. A slight increase in the reduced half-widths with increasing electron density was observed, just as predicted by theory. The absolute values, however, were smaller than the theoretical ones. There was good agreement with the experimental data of Bässler and Kock. The results of Wiese, Kelleher and Paquette differ from our data by 5-10% depending on the electron density.

  13. E-cigarettes: a need to broaden the debate.

    PubMed

    Latif, E; Nair, M

    2016-11-01

    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.

  14. Spectral broadening and its effect in Stark spectra of carotenoids

    NASA Astrophysics Data System (ADS)

    Krawczyk, Stanisław; Olszówka, Dorota

    2001-04-01

    Electrooptical parameters of eight carotenoids with different molecular structures were determined from the absorption and electroabsorption (Stark) spectra in glassy solvents and in poly(methyl methacrylate) films at temperatures 108-115 K. The results point to a limited significance of solvent-induced dipole moments in carotenoids resulting from local electric fields generated by solvent molecules, and indicate that the features in Stark spectra related to apparent dipole moments display a correlation with the bandwidth of individual vibronic transitions in absorption spectra. Model calculations show that it is possible to describe the Stark spectra by assuming a close link between the molecular polarizability and the inhomogeneous spectral shift. It is postulated that the dipole-related features in Stark spectra and the inhomogeneous broadening have a common origin in the distortions of molecular geometry in the form of torsional deformations about the single C-C bonds.

  15. Broadening the imaging phenotype of dysferlinopathy at different disease stages.

    PubMed

    Díaz, Jorge; Woudt, Lisanne; Suazo, Lionel; Garrido, Cristián; Caviedes, Pablo; CÁrdenas, Ana M; Castiglioni, Claudia; Bevilacqua, Jorge A

    2016-08-01

    MRI characterization of dysferlinopathy has been mostly limited to the lower limbs. We aimed to broaden the MRI description of dysferlinopathy and to correlate it with objective measures of motor dysfunction. Sequential whole-body axial MRI was performed in 27 patients with genetically confirmed dysferlinopathy classified according to disease duration. Spearman correlations of fatty infiltration scores versus Motor Function Measure (MFM) were calculated. Significant fatty infiltration was symmetrically present in early stages mainly in the posterior compartments of legs and thighs, thigh adductors, pelvic girdle, and some paravertebral muscles and the subscapularis. Later, fatty infiltration involved leg and thigh anterior compartments, arms and forearms, paravertebral, and trunk muscles. MRI infiltration score correlated positively with disease duration and negatively with MFM scale. We expand MRI characterization of dysferlinopathy and provide evidence for use of MRI scoring combined with motor functional scales to assess the natural course of disease. Muscle Nerve, 2016 Muscle Nerve 54: 203-210, 2016. © 2016 Wiley Periodicals, Inc.

  16. Comparing the line broadened quasilinear model to Vlasov code

    NASA Astrophysics Data System (ADS)

    Ghantous, K.; Berk, H. L.; Gorelenkov, N. N.

    2014-03-01

    The Line Broadened Quasilinear (LBQ) model is revisited to study its predicted saturation level as compared with predictions of a Vlasov solver BOT [Lilley et al., Phys. Rev. Lett. 102, 195003 (2009) and M. Lilley, BOT Manual. The parametric dependencies of the model are modified to achieve more accuracy compared to the results of the Vlasov solver both in regards to a mode amplitude's time evolution to a saturated state and its final steady state amplitude in the parameter space of the model's applicability. However, the regions of stability as predicted by LBQ model and BOT are found to significantly differ from each other. The solutions of the BOT simulations are found to have a larger region of instability than the LBQ simulations.

  17. Implementation of on-the-fly doppler broadening in MCNP

    SciTech Connect

    Martin, W. R.; Wilderman, S.; Brown, F. B.; Yesilyurt, G.

    2013-07-01

    A new method to obtain Doppler broadened cross sections has been implemented into MCNP, removing the need to generate cross sections for isotopes at problem temperatures. When a neutron of energy E enters a material region that is at some temperature T, the cross sections for that material at temperature T are immediately obtained 'on-the-fly' (OTF) by interpolation using a high order functional expansion for the temperature dependence of the Doppler-broadened cross section for that isotope at the neutron energy E. The OTF cross sections agree with the NJOY-based cross sections for all neutron energies and all temperatures in the range specified by the user, e.g., 250 K - 3200 K. The OTF methodology has been successfully implemented into the MCNP Monte Carlo code and has been tested on several test problems by comparing MCNP with conventional ACE cross sections versus MCNP with OTF cross sections. The test problems include the Doppler defect reactivity benchmark suite and two full-core VHTR configurations, including one with multiphysics coupling using RELAP5-3D/ATHENA for the thermal-hydraulic analysis. The comparison has been excellent, verifying that the OTF libraries can be used in place of the conventional ACE libraries generated at problem temperatures. In addition, it has been found that the OTF methodology greatly reduces the complexity of the input for MCNP, resulting in an order of magnitude decrease in the number of input lines for full-core configurations. Finally, for full-core problems with multiphysics feedback, the memory required to store the cross section data is considerably reduced with OTF cross sections and the additional computational effort with OTF is modest, on the order of 10-15%. (authors)

  18. A Simple Analytical Approximation to an Inhomogeneously-Broadened Dispersion Spectrum. Application to Absorption-Dispersion Admixtures.

    PubMed

    Bales, Barney L

    2016-09-19

    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.

  19. Wall-collision line broadening of molecular oxygen within nanoporous materials

    SciTech Connect

    Xu, Can T.; Lewander, Maerta; Andersson-Engels, Stefan; Svensson, Tomas; Svanberg, Sune; Adolfsson, Erik

    2011-10-15

    Wall-collision broadening of near-infrared absorption lines of molecular oxygen confined in nanoporous zirconia is studied by employing high-resolution diode-laser spectroscopy. The broadening is studied for pores of different sizes under a range of pressures, providing new insights on how wall collisions and intermolecular collisions influence the total spectroscopic line profile. The pressure series show that wall-collision broadening is relatively more prominent under reduced pressures, enabling sensitive means to probe pore sizes of porous materials. In addition, we show that the total wall-collision-broadened profile strongly deviates from a Voigt profile and that wall-collision broadening exhibits an additive-like behavior to the pressure and Doppler broadening.

  20. Gas temperature determination of non-thermal atmospheric plasmas from the collisional broadening of argon atomic emission lines

    NASA Astrophysics Data System (ADS)

    Rodero, A.; García, M. C.

    2017-09-01

    In this work we propose a new method allowing gas temperature determination in argon non-thermal plasma jets, based on the measurement of the collisional broadening of different argon atomic lines corresponding to transitions into both resonance levels s2 and s4 of the 3p54s configuration. The method was developed for fourteen lines: Ar I 978.45, 935.42, 922.45, 852.14, 840.82, 826.45, 750.39 (corresponding to transitions falling to level s2) and 965.77, 842.46, 810.37, 800.62, 751.46, 738.40, 727.29 nm (corresponding to transitions falling to level s4). A carefully study of the relative importance of all broadening mechanisms to the whole profile for these lines, under a broad range of experimental conditions, revealed that for electron densities and gas temperature lower than 1015 cm-3 and 2000 K, the Stark and Doppler broadenings can be neglected in the method, but the van der Waals contribution should not be ever discarded for gas temperature determination. The gas temperature of a microwave non-thermal plasma jet was determined using nine of these lines. Results were consistent with each other, and with those obtained from the rotational temperature derived from OH ro-vibrational band. Also, the influence of the air entrance on the collisional broadening of the lines has been studied and the way the method should be modified to include this effect is indicated.

  1. The effect of dispersion on spectral broadening of incoherent continuous-wave light in optical fibers.

    PubMed

    Soh, Daniel B S; Koplow, Jeffrey P; Moore, Sean W; Schroder, Kevin L; Hsu, Wen L

    2010-10-11

    In addition to fiber nonlinearity, fiber dispersion plays a significant role in spectral broadening of incoherent continuous-wave light. In this paper we have performed a numerical analysis of spectral broadening of incoherent light based on a fully stochastic model. Under a wide range of operating conditions, these numerical simulations exhibit striking features such as damped oscillatory spectral broadening (during the initial stages of propagation), and eventual convergence to a stationary, steady state spectral distribution at sufficiently long propagation distances. In this study we analyze the important role of fiber dispersion in such phenomena. We also demonstrate an analytical rate equation expression for spectral broadening.

  2. On the Stark broadening of Cr VI spectral lines in astrophysical plasma

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

  3. Fabrication of a 2-DOF electromagnetic energy harvester with in-phase vibrational bandwidth broadening

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Jui; Wu, Jia-Yin

    2016-09-01

    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.

  4. Broadening the Participation of Native Americans in Earth Science

    NASA Astrophysics Data System (ADS)

    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

  5. Superradiance and Subradiance in an Inhomogeneously Broadened Ensemble of Two-Level Systems Coupled to a Low-Q Cavity

    SciTech Connect

    Temnov, Vasily V.; Woggon, Ulrike

    2005-12-09

    The collective spontaneous emission of a fully inverted inhomogeneously broadened ensemble of N two-level systems coupled to a single-mode low-Q cavity is investigated numerically using Monte Carlo wave function technique. An intrinsically bi-exponential emission dynamics is found when the time scales of superradiance {tau}{sub sr} and inhomogeneous dephasing T{sub 2}*{approx}1/{delta}{omega}{sub inh} become comparable: a fast superradiant is followed by a slow subradiant decay. Experimental configurations using ensembles of quantum dots coupled to optical microcavities are proposed as possible candidates to observe the combined superradiant and subradiant energy relaxation.

  6. Broadening Participation: Mentoring Community College Students in a Geoscience REU

    NASA Astrophysics Data System (ADS)

    Smith, M.; Osborn, J.

    2015-12-01

    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.

  7. Workshops without Walls: Broadening Access to Science around the World

    PubMed Central

    Arslan, Betül K.; Boyd, Eric S.; Dolci, Wendy W.; Dodson, K. Estelle; Boldt, Marco S.; Pilcher, Carl B.

    2011-01-01

    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. PMID:21829326

  8. New theoretical and experimental methods for pressure broadened linewidths and their interpretation

    NASA Technical Reports Server (NTRS)

    Gelfand, J. J.

    1982-01-01

    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. Gas Temperature Determination in Argon-Helium Plasma at Atmospheric Pressure using van der Waals Broadening

    SciTech Connect

    Munoz, Jose; Yubero, Cristina; Calzada, Maria Dolores; Dimitrijevic, Milan S.

    2008-10-22

    The use of the van der Waals broadening of Ar atomic lines to determine the gas temperature in Ar-He plasmas, taking into account both argon and helium atoms as perturbers, has been analyzed. The values of the gas temperature inferred from this broadening have been compared with those obtained from the spectra of the OH molecular species in the discharge.

  10. Optoelectronic Workshops. Dynamical Instabilities in Homogeneously Broadened Lasers (9th) (23 August 1988)

    DTIC Science & Technology

    1988-08-23

    Broadened Lasers: Dye Lasers Karl Koch Modulation Techniques: Alexandrite Lasers Stephen Chakmakjian Summary Carlos R. Stroud B. CECOM Center for Night... alexandrite , another phonon assisted homogeneously broadened laser. He described in some detail modulation spectroscopic techniques developed in Rochester that...measurement determines the population cycling rate slow decay from level 1 may cause instabilities Single Laser AM Experiments ruby alexandrite modulator

  11. New theoretical and experimental methods for pressure broadened linewidths and their interpretation

    NASA Technical Reports Server (NTRS)

    Gelfand, J. J.

    1982-01-01

    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.

  12. The apparent spectral broadening of VLF transmitter signals during transionospheric propagation

    NASA Technical Reports Server (NTRS)

    Bell, T. F.; Inan, U. S.; Katsufrakis, J. P.; James, H. G.

    1983-01-01

    ISIS 1 and 2 and ISEE 1 VLF/ELF electric field wave data indicate the existence of a novel phenomenon, in which initially narrow band upgoing signals from ground-based VLF transmitters undergo a significant spectral broadening as they propagate through the ionosphere and protonosphere, up to altitudes in the 600-3800 km range. For transmitter signals in the 10-20 kHz range, the spectral broadening can be as high as 10 percent of the input signal's nominal frequency. In many cases, the bandwidth of the spectrally broadened signals is a strong function of the electric dipole antenna orientation with respect to the local direction of the earth's magnetic field. The unusual dispersion in the components of the spectrally broadened pulses suggests that the spectral broadening may be due to a Doppler shift effect in which the initial signals scatter from irregularities in the F region and couple into quasi-electrostatic modes of short wave length.

  13. Correction of Doppler-broadened Rayleigh backscattering effects in H2O dial measurements

    NASA Technical Reports Server (NTRS)

    Ansmann, A.; Bosenberg, J.

    1986-01-01

    A general method of solutions for treating effects of Doppler-broadened Rayleigh backscattering in H2O Differential Absorption Lidar (DIAL) measurements are described and discussed. Errors in vertical DIAL measuremtns caused by this laser line broadening effect can be very large and, therfore, this effect has to be accounted for accurately. To analyze and correct effects of Doppler-broadened Rayleigh backscattering in DIAL experiments, a generalized DIAL approximation was derived starting from a lidar equation, which includes Doppler broadening. To evaluate the accuracy of H2O DIAL measurements, computer simulations were performed. It was concluded that correction of Doppler broadened Rayleigh backscattering is possible with good accuracy in most cases of tropospheric H2O DIAL measurements, but great care has to be taken when layers with steep gradients of Mie backscattering like clouds or inversion layers are present.

  14. Analysis of broadened Mössbauer spectra using simple mathematical functions. Analysis of broadened Mössbauer spectra

    NASA Astrophysics Data System (ADS)

    Cabral-Prieto, A.

    2014-01-01

    Simulated and experimental broadened Mössbauer spectra are analyzed using several distribution functions. The resolution Hesse and Rübartsch data are reproduced in order to analyze the origin of the oscillations appearing in the recovered distribution function. The lined triangular distribution is used and some of its properties are described. The no implicit nth-nomial distribution function is introduced, complementing the Window and Hesse and Rübartasch no implicit distribution functions. This new no implicit distribution function gives similar results of those of Window's method. In addition, the Window method has also been modified by inserting a smoothing factor λ C . For 0 < λ C < 1 a hyperfine distribution with low resolution may be obtained; for λ C > 1, the opposite is obtained. The Levenberg-Marquardt algorithm is used to solve the involved Fredholm integral equation rather than the typical second order regularized algorithm. From the extracted hyperfine field distribution functions of the Mössbauer spectra of the amorphous and crystallized Fe70Cr2Si5B16 magnetic alloy the short range atomic order for the amorphous state of this alloy can be inferred.

  15. Theory of Self-Phase Modulation and Spectral Broadening

    NASA Astrophysics Data System (ADS)

    Shen, Y. R.; Yang, Guo-Zhen

    Self-phase modulation refers to the phenomenon in which a laser beam propagating in a medium interacts with the medium and imposes a phase modulation on itself. It is one of those very fascinating effects discovered in the early days of nonlinear optics (Bloembergen and Lallemand, 1966; Brewer, 1967; Cheung et al., 1968; Lallemand, 1966; Jones and Stoicheff, 1964; Shimizu, 1967; Stoicheff, 1963). The physical origin of the phenomenon lies in the fact that the strong field of a laser beam is capable of inducing an appreciable intensity-dependent refractive index change in the medium. The medium then reacts back and inflicts a phase change on the incoming wave, resulting in self-phase modulation (SPM). Since a laser beam has a finite cross section, and hence a transverse intensity profile, SPM on the beam should have a transverse spatial dependence, equivalent to a distortion of the wave front. Consequently, the beam will appear to have self-diffracted. Such a self-diffraction action, resulting from SPM in space, is responsible for the well-known nonlinear optical phenomena of self-focusing and self-defocusing (Marburger, 1975; Shen, 1975). It can give rise to a multiple ring structure in the diffracted beam if the SPM is sufficiently strong (Durbin et al., 1981; Santamato and Shen, 1984). In the case of a pulsed laser input, the temporal variation of the laser intensity leads to an SPM in time. Since the time derivative of the phase of a wave is simply the angular frequency of the wave, SPM also appears as a frequency modulation. Thus, the output beam appears with a self-induced spectral broadening (Cheung et al., 1968; Gustafson et al., 1969; Shimizu, 1967).

  16. Doppler Broadening Thermometry Based on Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Sun, Yu Robert; Cheng, Cunfeng; Tao, Lei-Gang; Tan, Yan; Kang, Peng; Liu, An-Wen; Hu, Shui-Ming

    2016-06-01

    A Doppler broadening thermometry (DBT) instrument is implemented based on a laser-locked cavity ring-down spectrometer. [1,2] It can be used to determine the Boltzmann constant by measuring the Doppler width of a molecular ro-vibrational transition in the near infrared. Compared with conventional direct absorption methods, the high-sensitivity of CRDS allows to reach satisfied precision at lower sample pressures, which reduces the influence due to collisions. By measuring the ro-vibrational transition of C_2H_2 at 787 nm, we demonstrate a statistical uncertainty of 6 ppm (part per million) in the determined linewidth by several hours' measurement at a sample pressure of 1.5 Pa. [3] However, the complicity in the spectrum of a polyatomic molecule induces potential systematic influence on the line profile due to nearby ``hidden'' lines from weak bands or minor isotopologues. Recently, the instrument has been upgraded in both sensitivity and frequency accuracy. A narrow-band fiber laser frequency-locked to a frequency comb is applied, and overtone transitions at 1.56 μm of the 12C16O molecule are used in the CRDS-DBT measurements. The simplicity of the spectrum of the diatomic CO molecule eliminates the potential influence from ``hidden'' lines. Our preliminary measurements and analysis show that it is feasible to pursue a DBT measurement toward the 1 ppm precision. H. Pan, et al., Rev. Sci. Instrum. 82, 103110 (2011) Y. R. Sun, et al., Opt. Expr., 19, 19993 (2011) C.-F. Cheng, et al., Metrologia, 52, S385 (2015)

  17. Some Strategies From SOARS for Broadening Participation in the Geosciences

    NASA Astrophysics Data System (ADS)

    Haacker-Santos, R.; Pandya, R.; Calhoun, A.

    2006-12-01

    The mission of SOARS® is to broaden participation in the geosciences by increasing the number of Black or African-American, American Indian or Alaska Native, Hispanic or Latino, female, and first-generation college students who enroll and succeed in graduate school in the atmospheric and related sciences. This mission contributes to national goals of developing a diverse, internationally competitive, and globally engaged workforce of scientists and engineers. SOARS is a multiyear undergraduate-to-graduate bridge program that uses three strategies: a strong learning community, a multidimensional mentoring program, and experience in research. Our presentation will describe SOARS' strategies in more detail, with an eye toward how such strategies might be adapted for other programs. To do this, we will draw upon recent research that documents how these strategies can be successfully implemented, including: - A survey of over 124 higher-education based STEM programs - A workshop report from the American Chemical Society emphasizing cooperation between industry and academia - An independent ethnographic study of the Significant Opportunities in Atmospheric and Related Science (SOARS®) program, administered by the University Corporation for Atmospheric Research (UCAR) In the 11 years since SOARS' founding, 104 students have participated in the program. Of those participants, 16 are still enrolled as undergraduates, and 60 have gone on to purse graduate school in STEM. Overall, this represents a success rate 91%. Of the 35 SOARS participants who have entered the workforce, 26 are in STEM related disciplines. Four SOARS participants have already earned their PhD, and additional 17 are in PhD programs. Seventeen protégés have earned Master's and entered the workforce, and 17 more protégés are enrolled in Master's programs.

  18. Cardiovascular RNA interference therapy: the broadening tool and target spectrum.

    PubMed

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

    2013-08-16

    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. Doppler broadening induced spectral shift effects on reactor safety

    SciTech Connect

    Alapour, A.

    1980-01-01

    It is commonly accepted that the resonance reaction rate of any material increases when the temperature is raised. However, in a nuclear reactor the increase in resonance reaction rates with temperature at relatively high energy shifts the neutron spectrum in such a way that a net decrease in the neutron flux results at lower energies. This finding suggested that the spectral shift could significantly affect the Doppler reactivity change, warranting further investigations. The objective was to study the physical characteristics of this new phenomenon and its effects on reactor safety. The desirability of studying this effect was strengthened by the presence of discrepancies between the calculated and measured integral experiments. An exact Doppler broadening kernel, based on the Maxwellian distribution of nuclear velocities, and an accurate integral transport method NDCRAB, capable of including resonance overlap of all materials present in the reactor cell, were used in this study. The ZPR-6 Assembly 7 benchmark, a typical LMFBR reactor, was used to quantify the Doppler reactivity change for an increase in fuel temperature and to analyze the natural UO/sub 3/ sample Doppler worth in this assembly. The quantification of the various components of the Doppler reactivity change shows that the fissile material, /sup 239/Pu, has a large negative Doppler effect and contributes a large fraction to the total negative effect. The calculated Doppler effect of the natural UO/sub 3/ sample in this assembly was in good agreement with the measured value. The calculated and measured values for an increase in sample temperature from 293-0K to 1100/sup 0/K wre -0.887 Ih/kgU and -0.868 Ih/kgU.

  20. Doppler Broadening Thermometry Based on Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hu, Shui-Ming; Cheng, Cunfeng; Wang, Jin; Tan, Yan; Sun, Yu Robert; Liu, An-Wen; Zhang, Jin-Tao

    2014-06-01

    A Doppler broadening thermometry is implemented using a laser-locked cavity ring-down spectrometer [1,2] combined with a temperature-stabilized sample cell. The temperature fluctuation of the gas sample cell is kept below 1 mK for hours. The probing laser is frequency locked at a longitudinal mode of a Fabry-Pérot interferometer made of ultra-low-expansion glass, and the spectral scan is implemented by scanning the sideband produced by an electro-optic modulator. As a result, a kHz precision has been maintained during the measurement of the spectrum of 10 GHz wide. A ro-vibrational line of C_2H_2 is measured at sample pressures of a few Pa. Using a pair of mirrors with a reflectivity of 0.99997 at 787 nm, we are able to detect absorption line profiles with a signal-to-noise ratio of 10^5. Fitting of the recorded spectra allows us to determine the Doppler width with a statistical uncertainty of 10 ppm. Further improvements on the experimental reproducibility and investigations on the collision effects will probably lead to an optical determination of the Boltzmann constant with an uncertainty of a few ppm. H. Pan, C.-F. Cheng, Y. R. Sun, B. Gao, A.-W. Liu, S.-M. Hu, ``Laser-locked, continuously tunable high resolution cavity ring-down spectrometer," Rev. Sci. Instrum. 82, 103110 (2011) Y. R. Sun, H. Pan, C.-F. Cheng, A.-W. Liu, J.-T. Zhang, S.-M. Hu, ``Application of cavity ring-down spectroscopy to the Boltzmann constant determination," Opt. Express, 19, 19993 (2011)

  1. Broadening Undergraduate Research Skills With A New Astrophysics Laboratory Class

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    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.

  2. Cortisol broadens memory of a non-stressful social interaction.

    PubMed

    Wiemers, Uta S; Wolf, Oliver T

    2015-05-01

    Stress and its associated hormonal cascade are known to enhance long-term memory consolidation. Recently we have shown that central details of a stressful situation (Trier Social Stress Test; TSST) are remembered better than central details of a similar but non-stressful control condition (friendly Trier Social Stress Test; fTSST). We reasoned that since cortisol concentrations increase during stress (TSST) but remain low during the control condition (fTSST), a pharmacological increase in cortisol during the fTSST might be able to mimic the stress effects observed previously. The objective of the study was to assess the impact of a pharmacologically induced cortisol increase during the non-stressful friendly TSST on long-term memory for details presented during this event. In a double-blind between-group design, participants (final sample: 20 men and 13 women) either received hydrocortisone (20 mg) or a placebo and were then exposed to a non-stressful social interaction (fTSST). Affect, salivary cortisol, and salivary alpha-amylase (sAA) were assessed before and after the fTSST. Recognition memory for objects presented during this situation was assessed 1 day later. Positive affect and sAA increased in response to the friendly TSST in both groups. Hydrocortisone enhanced memory for peripheral objects of the situation in men but not in women. Memory for central objects was not affected by the hormone. The results suggest that in a non-stressful positive social environment, cortisol induces a broadening rather than a narrowing of memory. In addition, the findings provide preliminary evidence that this effect might be more prominent in men.

  3. Isotopic Differences in CO Air Broadening and Shift Parameters

    NASA Astrophysics Data System (ADS)

    Smith, Mary-Ann H.; Malathy Devi, V.; Benner, D. Chris; Mantz, A. W.; Sung, K.; Brown, L. R.

    2012-10-01

    Line shape parameters were measured in the 2-0 bands at 2.3 µm for the three most abundant isotopologues of carbon monoxide at temperatures between 150 K and 298 K and total pressures up to 0.9 atm. These parameters include the Lorentz half-width coefficients with their temperature dependence exponents; pressure-induced line shift coefficients with their temperature dependences, speed dependence parameters, and off-diagonal relaxation matrix elements. For this, we recorded more than 50 high resolution (0.005 cm-1) spectra of CO and two of its isotopologues (13CO and C18O) using a coolable absorption cell [1] in the sample compartment of the Bruker IFS 125HR Fourier transform spectrometer at Jet Propulsion Laboratory. Line parameters were retrieved by broad-band constrained multispectrum least-squares fitting [2] of 16 or more spectra simultaneously. The individual line positions and intensities were constrained to their theoretical relationships in order to obtain the rovibrational (G, B, D, and H) and band intensity parameters, including Herman-Wallis coefficients, as has been done for CO2 previously [3]. Differences between the air-broadening results for the 12C16O band [4] and the 13C16O and 12C18O 2-0 bands [5] are examined. This research is supported by NASA’s Earth Science Atmospheric Composition Laboratory Research Program. Part of the research at the Jet Propulsion Laboratory, California Institute of Technology, the College of William and Mary, and Connecticut College was performed under contracts and grants with the National Aeronautics and Space Administration. 1. K. Sung et al., J. Mol. pectrosc. 262 (2010) 122. 2. D. C. Benner et al., J. Quant. Spectrosc. Radiat. Transfer 53 (1995) 705. 3. V. Malathy Devi et al., J. Mol. Spectrosc. 242 (2007) 90. 4. V. Malathy Devi et al., J. Quant. Spectrosc. Radiat. Transfer 113 (2012) 1013. 5. V. Malathy Devi et al., J. Mol. Spectrosc. 276-277 (2012) 33.

  4. Consequences and mechanisms of spike broadening of R20 cells in Aplysia californica.

    PubMed

    Ma, M; Koester, J

    1995-10-01

    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. Role of collisional broadening in Monte Carlo simulations of terahertz quantum cascade lasers

    SciTech Connect

    Matyas, Alpar; Lugli, Paolo; Jirauschek, Christian

    2013-01-07

    Using a generalized version of Fermi's golden rule, collisional broadening is self-consistently implemented into ensemble Monte Carlo carrier transport simulations, and its effect on the transport and optical properties of terahertz quantum cascade lasers is investigated. The inclusion of broadening yields improved agreement with the experiment, without a significant increase of the numerical load. Specifically, this effect is crucial for a correct modeling at low biases. In the lasing regime, broadening can lead to significantly reduced optical gain and output power, affecting the obtained current-voltage characteristics.

  6. Method for separation of homogeneous and inhomogeneous components of spectral broadening of rigid systems

    SciTech Connect

    Litvinyuk, I.V.

    1997-01-30

    A method is suggested that allows separation of the contributions from homogeneous and inhomogeneous broadening (IB) to a total spectral contour of rigid systems. Based upon a simple convolution model of inhomogeneous broadening, the method allows calculation of homogeneously broadened spectra and an inhomogeneous distribution function (IDF) from the measured excitation-wavelength-dependent fluorescence spectra of the system. The method is applied successfully to the solid solution of coumarin 334 (C334) in poly(methyl methacrylate) (PMMA) glass at 293 K. 16 refs., 5 figs.

  7. Determination of Van der Waals broadening at temperatures of astrophysical interest.

    NASA Technical Reports Server (NTRS)

    Evans, J. M., Jr.; Cooper, J.

    1972-01-01

    Discussion of the results of experiments analyzing the widths of shock-excited emission lines at temperatures of about 5000 K. The width of two neutral silicon lines (4102 and 5948 A) were measured as broadened by argon, and the shift of one of these lines (4102 A) was determined. Likewise, the width one of the lines of cesium (4593 A) was measured as broadened by argon and neon. These data are compared with other experimental data to determine the temperature dependence of the broadening. Significant disagreements with simple theory are found, the experimental values of the widths being larger than the theoretical values by factors of 1.5-2.

  8. Saturation effects and inhomogeneous broadening in Doppler-free degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Steel, D. G.; Lam, J. F.

    1981-12-01

    We have performed experiments to study the saturation properties of degenerate four-wave mixing (DFWM) in inhomogeneously broadened material. The experiments were performed on line-center in SF 6 using a CW CO 2 laser on the P16 line at 10.6 μm. Measured peak reflectivities of 1.7 x 10 -4 are in reasonable agreement with a simple two-level model. This model also appears to correctly account for the observed saturation effects. While the material is clearly inhomogeneously broadened, both the experimental and theoretical reflectivity scale as though the material was homogeneously broadened.

  9. Gain and Raman line-broadening with graphene coated diamond-shape nano-antennas.

    PubMed

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

    2015-10-07

    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.

  10. Si 6142 and 6155 Å lines in stellar atmospheres: Stark broadening effect

    NASA Astrophysics Data System (ADS)

    Dimitrijević, M. S.; Popović, L. Č.; Ryabchikova, T.

    2002-07-01

    We study the influence of Stark broadening effect on Si I lines in the roAp 10 Aql star, where the lines are asymmetrical and shifted. First we have calculated Stark broadening parameters using by the semi-classical method for two Si I lines: 6142.48 Å and 6155.13 Å. We have adopted SYNTH code to include into account both Stark width and shift for these lines. From comparison of our calculation data with observations we found that Stark broadening plus stratification effect can explain the width and the asymmetry of the Si I lines in the atmosphere of roAp 10 Aql star.

  11. Pressure broadening calculations for OH in collisions with argon: Rotational, vibrational, and electronic transitions

    NASA Astrophysics Data System (ADS)

    Dagdigian, Paul J.

    2017-03-01

    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.

  12. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work.

    PubMed

    Di Fabio, Annamaria; Maree, Jacobus G

    2016-01-01

    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.

  13. Using a Transdisciplinary Interpretive Lens to Broaden Reflections on Alleviating Poverty and Promoting Decent Work

    PubMed Central

    Di Fabio, Annamaria; Maree, Jacobus G.

    2016-01-01

    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 PMID:27148115

  14. Polarization-Sensitive Measurements Of Magnetic Fields In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, Showera; Wallace, Matthew S.; Neill, Paul; Presura, Radu

    2016-10-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult in this regime because the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Using an idea proposed by Tessarin et al. (2011), we have measured the field in magnetized laser plasmas and in the current-driven exploding wire plasmas. Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator, and for wire array plasmas driven by the 1 MA configuration of the Zebra generator. We explore the response of the Al III 4s 2S1/2- 4p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma in two orthogonal polarizations. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength was measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES Grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  15. Anomalous front broadening during spontaneous imbibition in a matrix with elongated pores

    PubMed Central

    Gruener, Simon; Sadjadi, Zeinab; Hermes, Helen E.; Kityk, Andriy V.; Knorr, Klaus; Egelhaaf, Stefan U.; Rieger, Heiko; Huber, Patrick

    2012-01-01

    During spontaneous imbibition, a wetting liquid is drawn into a porous medium by capillary forces. In systems with comparable pore length and diameter, such as paper and sand, the front of the propagating liquid forms a continuous interface. Sections of this interface advance in a highly correlated manner due to an effective surface tension, which restricts front broadening. Here we investigate water imbibition in a nanoporous glass (Vycor) in which the pores are much longer than they are wide. In this case, no continuous liquid–vapor interface with coalesced menisci can form. Anomalously fast imbibition front roughening is experimentally observed by neutron imaging. We propose a theoretical pore-network model, whose structural details are adapted to the microscopic pore structure of Vycor glass and show that it displays the same large-scale roughening characteristics as observed in the experiment. The model predicts that menisci movements are uncorrelated, indicating that despite the connectivity of the network the smoothening effect of surface tension on the imbibition front roughening is negligible. These results suggest a new universality class of imbibition behavior, which is expected to occur in any matrix with elongated, interconnected pores of random radii. PMID:22689951

  16. Measurement Of Magnetic Fields In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, Showera; Wallace, Matthew S.; Neill, Paul; Presura, Radu

    2015-11-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult in this regime because the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Using an idea proposed by Tessarin et al. (2011), we have measured the field in magnetized laser plasmas and the magnetized precursor of wire array z-pinches. Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator, and for wire array plasmas driven by the 1 MA configuration of the Zebra generator. We explore the response of the Al III 4s 2S1/2- 4p 2P1 / 2 , 3 / 2 doublet components and the C IV 3s 2S1/2- 3p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength was measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  17. Magnetic Field Measurement in Magnetized Laser Plasmas Using Zeeman Broadening Diagnostics

    NASA Astrophysics Data System (ADS)

    Haque, S.; Wallace, M. S.; Arias, A.; Morita, T.; Plechaty, C.; Huntington, C.; Martinez, D.; Ross, S. J.; Park, H.-S.; Presura, R.

    2013-10-01

    The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. The measurements are difficult when the field orientation is fluctuating in the plasma volume or when the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. Based on an idea proposed by Tessarin et al. (2011), we implemented a solution to this problem to the field measurement in magnetized laser plasmas. High resolution spectra were obtained at the Nevada Terawatt Facility for plasmas created by 20 J, 400 fs Leopard laser pulses in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator. The components of the Al III 3s 2S1/2 - 3p 2P1 / 2 , 3 / 2 were recorded with space resolution along the direction normal to the target, which coincided with the magnetic field radius. In several shots, the spectra were time gated for 10 ns at different values of the magnetic field. In these measurements the Zeeman splitting was not resolved, but the magnetic field strength can be measured from the difference between the widths of the line profiles. This work was supported by the DOE/OFES grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

  18. Broadening the trans-contextual model of motivation: A study with Spanish adolescents.

    PubMed

    González-Cutre, D; Sicilia, Á; Beas-Jiménez, M; Hagger, M S

    2014-08-01

    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.

  19. Progress with On-The-Fly Neutron Doppler Broadening in MCNP

    SciTech Connect

    Brown, Forrest B.; Martin, William R.; Yesilyurt, Gokhan; Wilderman, Scott

    2012-06-18

    The University of Michigan, ANL, and LANL have been collaborating on a US-DOE-NE University Programs project 'Implementation of On-the-Fly Doppler Broadening in MCNP5 for Multiphysics Simulation of Nuclear Reactors.' This talk describes the project and provides results from the initial implementation of On-The-Fly Doppler broadening (OTF) in MCNP and testing. The OTF methodology involves high precision fitting of Doppler broadened cross-sections over a wide temperature range (the target for reactor calculations is 250-3200K). The temperature dependent fits are then used within MCNP during the neutron transport, for OTF broadening based on cell temperatures. It is straightforward to extend this capability to cover any temperature range of interest, allowing the Monte Carlo simulation to account for a continuous distribution of temperature ranges throughout the problem geometry.

  20. Spectral broadening of VLF transmitter signals observed on DE 1 - A quasi-electrostatic phenomenon?

    NASA Technical Reports Server (NTRS)

    Inan, U. S.; Bell, T. F.

    1985-01-01

    Spectrally broadened VLF transmitter signals are observed on the DE 1 satellite using alternatively both electric and magnetic field sensors. It is found that at times when the electric field component undergoes significant bandwidth expansion (up to about 110 Hz) the magnetic field component has a bandwidth of less than 10 Hz. The results support the theory that the off-carrier components are quasi-electrostatic in nature. Measurement of the absolute E and B field magnitudes of the broadened signals are used to determine the wave Poynting vector. It is found that the observed power levels can be understood without invoking any strong amplification process that operates in conjunction with the spectral broadening. The implications of this finding in distinguishing among the various possible mechanisms for spectral broadening are discussed.

  1. Experimental and Theoretical Studies of Pressure Broadened Alkali-Metal Atom Resonance Lines

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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.

  2. Measurements of H2O-broadening coefficients of O2 A-band lines

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We report laboratory measurements of H2O-broadening coefficients of O2 absorption lines in the A-band near 13,000 cm-1. For this, four spectra of oxygen gas mixed with water vapor were recorded with a high resolution Fourier transform spectrometer for total pressures ranging from 125 to 175 Torr at 323 K, and a fifth at 175 Torr and 365 K. Broadening coefficients of 39 transitions (up to J″ = 21) were retrieved from the measured spectra through fits using Galatry line profiles. Values at room temperature (296 K) were then extrapolated and compared with previous determinations in the A-band and millimeter waves region. This enables to resolve some controversial issues related to the inconsistencies between these studies. Finally, comparing our results with the line broadening coefficients by dry air confirms that H2O-broadenings of oxygen lines are, on average, 10% larger than those by dry air.

  3. Hyperfine dipole-dipole broadening of selective reflection spectroscopy at the gas-solid interface

    NASA Astrophysics Data System (ADS)

    Meng, Tengfei; Ji, Zhonghua; Zhao, Yanting; Xiao, Liantuan; Jia, Suotang

    2016-09-01

    We theoretically and experimentally investigate hyperfine dipole-dipole broadening in the selective reflection (SR) spectroscopy at the gas-solid interface with the atomic density of 1014-1015 cm-3. The two-level SR theory considering pump beam and dipole-dipole interaction between excited-state atom and ground-state atom is presented. The numerical simulation of the SR spectrum is in agreement with experimental results. The reduction of spectral width is observed by introducing a pump beam which is an effective technique to improve the resolution of spectroscopy. We analyze the dependence of dipole-dipole broadening on atomic density and pump beam power. This study is helpful for the description of the SR spectroscopy at the gas-solid interface where the Doppler broadening is comparable with dipole-dipole broadening.

  4. A study of Stark broadening for the diagnostic of runaway electrons in ITER

    NASA Astrophysics Data System (ADS)

    Rosato, J.; Pandya, S. P.; Logeais, Ch.; Meireni, M.; Hannachi, I.; Reichle, R.; Barnsley, R.; Marandet, Y.; Stamm, R.

    2017-03-01

    We investigate the Stark broadening of hydrogen lines in tokamak edge plasma conditions in the presence of a beam of relativistic "runaway" electrons. The possibility for a diagnostic involving passive spectroscopy is discussed.

  5. The influence of Stark broadening on Cr II spectral line shapes in stellar atmospheres

    NASA Astrophysics Data System (ADS)

    Dimitrijević, M. S.; Ryabchikova, T.; Simić, Z.; Popović, L. Č.; Dačić, M.

    2007-07-01

    Aims:We consider the effect of Stark broadening on the shapes of Cr ii spectral lines observed in stellar atmospheres of the middle part of the main sequence. Methods: Stark broadening parameters were calculated by the semiclassical perturbation approach. For stellar spectra synthesis, the improved version synth3 of the code synth for synthetic spectrum calculations was used. Results: Stark broadening parameters for Cr ii spectral lines of seven multiplets belonging to 4s-4p transitions were calculated. New calculated Stark parameters were applied to the analysis of Cr ii line profiles observed in the spectrum of Cr-rich star HD 133792. Conclusions: We found that Stark broadening mechanism is very important and should be taken into account, especially in the study of Cr abundance stratification.

  6. High resolution diode laser spectroscopy of H2O spectra broadened by nitrogen and noble gases

    NASA Astrophysics Data System (ADS)

    Kapitanov, Venedikt A.; Osipov, Konstantin Yu.; Protasevich, Alexander E.; Ponurovskiy, Yakov Ya.

    2014-11-01

    The absorption spectra of pure H2O with mixtures of broadening gases N2, Ar, Xe, He, Ar and air have been measured in 1.39 mμ spectral region by high resolution spectrometer based on diode laser (DFB NEL, Japan). For the processing of pure water spectra and it's mixtures with a different broadening gases in a wide pressure range we used a multispectrum fitting procedure developed at IAO. The program is based on a relatively simple Rautian-Sobel'man line profile and linear pressure dependence of the line profile parameters. H2O measured spectra bulk processing results in the retrieving of such line parameters: zero-pressure line center positions, intensities, self-broadening and self-shift coefficients of pure water, broadening and shift coefficients for other gases which are describes the experiment with the minimum residuals in a wide pressure range.

  7. VizieR Online Data Catalog: Stark broadening of Cd I spectral lines (Simic+, 2005)

    NASA Astrophysics Data System (ADS)

    Simic, Z.; Dimitrijevic, M. S.; Milovanovic, N.; Sahal-Brechot, S.

    2005-09-01

    Stark broadening parameters, widths, and shifts for 33 CdI singlets and 37 triplets were calculated using the semiclassical perturbation method. The results were compared with available experimental and theoretical data. Also, regularity in the spectral series 5s2 1S-np 1Po was investigated. The influence of Stark broadening was analyzed in A-type stellar atmospheres. (2 data files).

  8. A method for measuring magnetic fields in sunspots using Zeeman-broadened absorption lines

    NASA Astrophysics Data System (ADS)

    Oostra, Benjamin

    2017-04-01

    We present measurements of magnetic fields in several sunspots using high-resolution spectra obtained with the ESPARTACO spectrograph at the Universidad de los Andes, with the aim to explore experimental possibilities for students. Because the Zeeman line splitting is smaller than the line width, our work only observes broadened absorption lines. This broadening, however, can be measured and suitably modeled, giving realistic quantitative results.

  9. Extensional-wave stopband broadening across the joint of pipes of different thickness.

    PubMed

    Su, Yuanda; Tang, Xiaoming; Liu, Yukai; Xu, Song; Zhuang, Chunxi

    2015-11-01

    The stopband of pipe extensional waves is an interesting natural phenomenon. This study demonstrates an important extension of this phenomenon. That is, the stopband can be effectively broadened by transmitting the waves across the joint of pipes of different thickness. The theoretical and experimental results reveal the detailed process of stopband forming along the pipe and the band broadening across the pipe joint. The result can be utilized to provide a method for logging while drilling acoustic isolation design.

  10. Broadening the Study of Participation in the Life Sciences: How Critical Theoretical and Mixed-Methodological Approaches Can Enhance Efforts to Broaden Participation

    ERIC Educational Resources Information Center

    Metcalf, Heather

    2016-01-01

    This research methods Essay details the usefulness of critical theoretical frameworks and critical mixed-methodological approaches for life sciences education research on broadening participation in the life sciences. First, I draw on multidisciplinary research to discuss critical theory and methodologies. Then, I demonstrate the benefits of these…

  11. Broadening the Study of Participation in the Life Sciences: How Critical Theoretical and Mixed-Methodological Approaches Can Enhance Efforts to Broaden Participation

    ERIC Educational Resources Information Center

    Metcalf, Heather

    2016-01-01

    This research methods Essay details the usefulness of critical theoretical frameworks and critical mixed-methodological approaches for life sciences education research on broadening participation in the life sciences. First, I draw on multidisciplinary research to discuss critical theory and methodologies. Then, I demonstrate the benefits of these…

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  13. Broadening of seismogram envelopes in the randomly inhomogeneous lithosphere based on the parabolic approximation: southeastern Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Sato, Haruo

    1989-12-01

    Analyzing horizontal component seismograms of small earthquakes with intermediate hypocentral distances in southeastern Honshu, Japan, we found that time widths of seismogram envelopes around direct S waves are much longer than source duration times estimated from their magnitudes. The time lags of the maximum amplitude and the half maximum after the peak were measured from the onset of the direct S wave arrival from band-pass-filtered seismograms from 2 to 32 Hz. Even though there is considerable scatter, both the time lags are found to increase with increasing hypocentral distance up to 305 km. We hypothesize that pulse shape broadens and the maximum amplitude is reduced after propagating through the random structure of the lithosphere. The parabolic approximation theoretically predicts that the long-wavelength component of velocity inhomogeneities compared with the wavelength of seismic waves produces diffraction fluctuations and makes seismogram envelopes broaden with increasing travel distance in the saturated regime. Supposing a Gaussian autocorrelation function for the randomness and an empirical frequency dependent attenuation, we propose a formula for the temporal change in the power spectral density of seismic waves. Applying this formula to the observed data, we statistically evaluated the scale of random inhomogeneities: the mean square fractional velocity fluctuation was estimated to be 10-3 times the correlation distance a in kilometers.

  14. Broadening the U.S. alfalfa germplasm base

    USDA-ARS?s Scientific Manuscript database

    Over 4000 alfalfa (Medicago sativa L.) plant introductions (PIs) exist in the USDA-ARS National Plant Germplasm System (NPGS). NAAIC has discussed/proposed pre-breeding efforts to utilize this germplasm for creating pre-commercial alfalfa germplasm. Funding constraints have been one impediment to th...

  15. Anomalous Hole Burning in Polymers with Inhomogeneous Broadening

    DTIC Science & Technology

    1991-10-01

    dimensional semiconductors . It is well-known that polymers exhibit giant nonlinear optical 4 susceptibilities with fast responses. They have attracted...polymers. 2 A phase-space filling model has been proposed 3 which provides a good explanation for the hole burning and excitonic Stark effect in low

  16. Three-wave vibrational mode broadening for Fibonacci one-dimensional quasicrystals

    NASA Astrophysics Data System (ADS)

    Kats, E. I.; Muratov, A. R.

    2005-11-01

    A one-dimensional Fibonacci chain is used to model vibrational mode broadening in icosahedral quasicrystals (i-QCs). All calculations are performed self-consistently for various finite size approximants at temperatures higher than the Debye temperature, TD. This approach is extended to three-dimensional systems as well. It is shown that vibrational spectra depend crucially on the Fibonacci chain mass ratio m. For m = 3, which roughly mimics AlPdMn i-QC, there are three almost dispersionless optic modes separated from the acoustic mode by three large gaps, and for m = 1/3, which mimics ZnMgY i-QC, there is one dispersionless optic mode and one acoustic mode. For the first time we provide a qualitative model which predicts experimentally observed phonon spectrum broadening of i-QC. It is shown that three wave broadening for both one-dimensional and three-dimensional Fibonacci i-QCs is the leading mechanism of spectrum broadening. For the intermediate range of mode coupling constants, it scales with the mode frequency ω as c1ω+c2ω2 (where c1 and c2 are some numerical constants). For smaller values of the coupling constant, phonon broadening is proportional to ω3. We conclude that for a system with a non-simple elementary cell, vibrational spectrum broadening is always larger than for a system with a primitive cell (provided all other characteristics are the same).

  17. Stark broadening corrections to laser-induced fluorescence temperature measurements in a hydrogen arcjet plume.

    PubMed

    Storm, P V; Cappelli, M A

    1996-08-20

    Laser-induced fluorescence of the H(α) transition of atomic hydrogen has previously been performed in the plume of a hydrogen arcjet thruster. Measurements of plasma velocity and temperature, based on the Doppler shift and broadening of the H(α) line shape, were previously published [Appl. Opt. 32, 6117 (1993)]. In that paper the Stark broadening of the H(α) transition was estimated from static-ion calculations performed in the early 1970's and found to be negligible in comparison with the Doppler broadening. However, more recent dynamic-ion calculations have shown the Stark broadening to be considerably larger than was previously assumed, resulting in inaccurate temperature measurements. We present a reanalysis of the fluorescence data, taking into account the improved Stark broadening calculations. The correct atomic hydrogen translation temperature and electron number density are obtained from the Doppler and Stark broadening components of the measured line shape. The results indicate a substantial drop in temperature from those previously reported.

  18. Non-symmetric broadening of the reflection notch in polymer stabilized cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Natarajan, Lalgudi V.; Voss, Jimmy R.; Tondiglia, Vincent P.; Yang, Deng-Ke; White, Timothy J.; Bunning, Timothy J.

    2010-08-01

    Non-symmetric broadening (to the blue side) of a cholesteric reflection notch was observed when a cell containing diacrylate and monoacrylate nematic LC monomers, a chiral dopant, nematic LC and a photoinitiator was exposed to very low intensity (microwatts) of 335 nm UV light. At very low intensity, the polymerization rate is very slow and takes a long time to complete as observed by real-time monitoring experiments. The polymerized scaffold templates the original liquid crystal helical structure. The 335 nm light is highly absorbed by the system which generates an intensity gradient throughout the thickness of the cell. This gradient produces a free radical density gradient in the later stage of the polymerization when diffusion is slowed by the growing polymer network. Since more monomer is consumed at the front half of the cell, a counter diffusion of chiral dopant towards the cell backside is observed. This leads to a local increase in the HTP causing a local blue shift of the notch wavelength. The net result observed in transmission is a broadening of the reflection bandwidth from 70 nm to 200 nm where the broadening occurs only to the blue side of the original notch. By varying the intensity of the UV source on one side of the substrate, the broadening magnitude could be controlled. Simultaneous UV illumination from both sides of the cell reduced the broadening considerably. The broadened notch was switchable at high electrical field (20V/μm).

  19. An In-situ method for the study of strain broadening usingsynchrotronx-ray diffraction

    SciTech Connect

    Tang, Chiu C.; Lynch, Peter A.; Cheary, Robert W.; Clark, Simon M.

    2006-12-15

    A tensonometer for stretching metal foils has beenconstructed for the study of strain broadening in x-ray diffraction lineprofiles. This device, which is designed for use on the powderdiffractometer in Station 2.3 at Daresbury Laboratory, allows in-situmeasurements to be performed on samples under stress. It can be used fordata collection in either transmission or reflection modes using eithersymmetric or asymmetric diffraction geometries. As a test case,measurements were carried out on a 18mum thick copper foil experiencingstrain levels of up to 5 percent using both symmetric reflection andsymmetric transmission diffraction. All the diffraction profilesdisplayed peak broadening and asymmetry which increased with strain. Themeasured profiles were analysed by the fundamental parameters approachusing the TOPAS peak fitting software. All the observed broadenedprofiles were modelled by convoluting a refineable diffraction profile,representing the dislocation and crystallite size broadening, with afixed instrumental profile pre-determined usinghigh quality LaB6reference powder. The de-convolution process yielded "pure" sampleintegral breadths and asymmetry results which displayed a strongdependence on applied strain and increased almost linearly with appliedstrain. Assuming crystallite size broadening in combination withdislocation broadening arising from fcc a/2<110>111 dislocations,we have extracted the variation of mechanic al property with strain. Theobservation of both peak asymmetry and broadening has been interpreted asa manifestation of a cellular structure with cell walls and cellinteriors possessing high and low dislocation densities.

  20. Design of suitable carrier buffer for free-flow zone electrophoresis by charge-to-mass ratio and band broadening analysis.

    PubMed

    Kong, Fan-Zhi; Yang, Ying; He, Yu-Chen; Zhang, Qiang; Li, Guo-Qing; Fan, Liu-Yin; Xiao, Hua; Li, Shan; Cao, Cheng-Xi

    2016-09-01

    In this work, charge-to-mass ratio (C/M) and band broadening analyses were combined to provide better guidance for the design of free-flow zone electrophoresis carrier buffer (CB). First, the C/M analyses of hemoglobin and C-phycocyanin (C-PC) under different pH were performed by CLC Protein Workbench software. Second, band dispersion due to the initial bandwidth, diffusion, and hydrodynamic broadening were discussed, respectively. Based on the analyses of the C/M and band broadening, a better guidance for preparation of free-flow zone electrophoresis CB was obtained. Series of experiments were performed to validate the proposed method. The experimental data showed high accordance with our prediction allowing the CB to be prepared easily with our proposed method. To further evaluate this method, C-PC was purified from crude extracts of Spirulina platensis with the selected separation condition. Results showed that C-PC was well separated from other phycobiliproteins that have similar physicochemical properties, and analytical grade product with purity up to 4.5 (A620/A280) was obtained.

  1. Brokering Relationships, Broadening Impacts: COSEE Florida's Ocean Science Learning Network

    NASA Astrophysics Data System (ADS)

    Paul, V. J.; Diederick, L.

    2016-02-01

    With the ever-increasing elevation of broader impacts (BI) in the evaluation of research proposals to various funding agencies, both public and private, COSEE Florida, with its statewide Ocean Science Learning Network, has been well-positioned to assist ocean scientists looking to enhance their BI activities. This presentation will outline the strategies employed to effectively engage more than 200 ocean scientists in educational outreach over a five-year period and highlight the impacts of their participation.

  2. Program Proposal

    ERIC Educational Resources Information Center

    Baskas, Richard S.

    2012-01-01

    A study was conducted to determine if a deficiency, or learning gap, existed in a particular working environment. To determine if an assessment was to be conducted, a program proposal would need to be developed to explore this situation. In order for a particular environment to react and grow with other environments, it must be able to take on…

  3. Microscopic nature of inhomogeneous line broadening: Analysis of the excitation-line-narrowing spectra of Cf4+ in CeF4

    NASA Astrophysics Data System (ADS)

    Liu, G. K.; Huang, Jin; Beitz, James V.

    1993-11-01

    Optical transitions between 5f states of tetravalent californium ion doped (1 metal-atom %) into CeF4 exhibit unusually large inhomogeneous broadening. The nature of the inhomogeneous broadening in this system has been studied by using fluorescence line narrowing and excitation line narrowing (ELN). It is shown that the energy distributions of different electronic states of Cf4+ in this system are correlated. In the ELN experiments, reduced excitation linewidth was obtained when selectively monitoring fluorescence emission. A linear relation was observed between the excitation energies of crystal-field states of the G54' manifold and the fluorescence wavelength monitored across the inhomogeneous profile of a G56'-F76' transition. Analysis of these results by means of a microscopic theory proposed by Laird and Skinner [J. Chem. Phys. 90, 3880 (1989)] has provided insights into the structural properties of this disordered system.

  4. Influence of resonant collisions on the self-broadening of acetylene

    NASA Astrophysics Data System (ADS)

    Lehmann, Kevin K.

    2017-03-01

    Iwakuni et al. [Phys. Rev. Lett. 117, 143902 (2016)] have reported an ortho-para alternation of ˜10% in the self pressure broadening coefficients for ro-vibrational lines of the C2H2 transitions in the ν1+ν3 C-H (local mode) overtone band near 197 THz (1.52 μm). These authors attributed this effect to the contribution of resonant collisions, where the rotational energy change of one molecule is exactly compensated by the rotational energy change of its collision partner. Resonant collisions are known to be important in the case of self pressure broadening of highly polar molecules, such as HCN, but have not previously been invoked in the case of nonpolar molecules, such as acetylene, where the long range potential is dominated by the quadrupole-quadrupole electrostatic interaction. In the present work, the simple semiclassical Anderson-theory approach is used to estimate the rates of C2H2-C2H2 rotationally inelastic collisions and these used to predict pressure broadening rates, ignoring other contributions to the broadening, which should not have resonant enhancements. It is found that exactly resonant collisions do not make a major contribution to the broadening and these calculations predict an ortho-para alternation of the pressure broadening coefficients far below what was inferred by Iwakuni et al. The present results are consistent with a large body of published work that reported self-broadening coefficients of C2H2 ro-vibrational transitions that found negligible dependence on the vibrational transition and no even-odd alternation, even for Q and S branch transitions where any such effect is predicted to be much larger than for the P and R branch transitions studied by Iwakuni et al.

  5. Line broadening in the 77 K 57Fe-Mössbauer spectra of some ferrous iron-containing medicines

    NASA Astrophysics Data System (ADS)

    Arredondo S., P. I.; Barrero, C. A.; Garcia, K. E.; Greneche, J. M.

    We report line broadening in the 77 K 57Fe Mössbauer spectra of some commercially available medicines based on ferrous sulfates and on ferrous fumarates. While introducing only a single ferrous doublet is required to fit the RT spectra of all samples, on the contrary the line shapes of the 77 K spectra are properly described with two ferrous doublets. We discuss eight different static and dynamic hypotheses as possible physical origins for these two doublets, but finally we propose that the reasons are similar for the ferrous sulfates and for the ferrous fumarates containing medicines, and it can be due to the presence of easily dehydrated and hydrated ferrous compounds. The presence of several hydrated sulfates was confirmed by RT Raman spectroscopy. Possible implications of these results related with the hydrated character by which the active parts of the medicines are fabricated by the pharmaceutical companies are also discussed.

  6. Absorption Spectra of Broadened Sodium Resonance Lines in Presence of Rare Gases

    SciTech Connect

    Chung, H-K; Shurgalin, M; Babb, J F

    2002-09-11

    The pressure broadening of alkali-metal lines is a fundamental problem with numerous applications. For example, the sodium resonance lines broadened by xenon are important in the production of broad spectra emitted in the HPS (High-Pressure Sodium) lamp and they potentially can be used for gas condition diagnostics. Broadened absorption lines of alkali-metal atoms are prominent in the optical spectra of brown dwarfs and understanding the broadening mechanism will help elucidate the chemical composition and atmospheric properties of those stars. The far-line wing spectra of sodium resonance lines broadened by rare gases are found to exhibit molecular characteristics such as satellites and hence the total absorption coefficients for vapors of Na atoms and perturbing rare gas atoms can be modeled as Na-RG (rare gas) molecular absorption spectra. In this work, using carefully chosen interatomic potentials for Na-RG molecules we carry out quantum-mechanical calculations for reduced absorption coefficients for vapors composed of Na-He, Na-Ar, and Na-Xe. Calculated spectra are compared to available experimental results and the agreement is good in the measured satellite positions and shapes.

  7. Electron momentum densities near Dirac cones: Anisotropic Umklapp scattering and momentum broadening.

    PubMed

    Hiraoka, N; Nomura, T

    2017-04-03

    The relationship between electron momentum densities (EMDs) and a band gap is clarified in momentum space. The interference between wavefunctions via reciprocal lattice vectors, making a band gap in momentum space, causes the scattering of electrons from the first Brillouin zone to the other zones, so-called Umklapp scattering. This leads to the broadening of EMDs. A sharp drop of the EMD in the limit of a zero gap becomes broadened as the gap opens. The broadening is given by a simple quantity, E g /v F , where E g is the gap magnitude and v F the Fermi velocity. As the ideal case to see such an effect, we investigate the EMDs in graphene and graphite. They are basically semimetals, and their EMDs have a hexagonal shape enclosed in the first Brillouin zone. Since the gap is zero at Dirac points, a sharp drop exists at the corners (K/K' points) while the broadening becomes significant away from K/K's, showing the smoothest fall at the centers of the edges (M's). In fact, this unique topology mimics a general variation of the EMDs across the metal-insulator transition in condensed matters. Such an anisotropic broadening effect is indeed observed by momentum-density-based experiments e.g. x-ray Compton scattering.

  8. A comparison of homogeneous and inhomogeneous absorption broadening in Nd doped Gadolinium Gallium Garnet

    NASA Astrophysics Data System (ADS)

    Ferri, Christopher; Ghosh, Sayantani

    2015-03-01

    We perform a temperature dependent optical absorption study of the 4I9 / 2-->4F3 / 2 (Zn -->Rn)transition of the Neodymium dopant in Neodymium(III) doped Gadolinium Gallium Garnet. Absorption spectra are acquired for these transitions as a function of temperature from 12K to 300K. The absorption peaks are subsequently fit with Voigt profiles to measure the homogeneous and inhomogeneous broadening for each transition. We find that for the Z1 -->R2 transition the homogeneous and inhomogeneous broadening are of the same order. Below 80K, for the Z1 -->R1 transition, the homogeneous broadening is below the resolution of our spectrometer (1.85 cm-1) resulting in a lower bound of ~ 18 ps for the excited state lifetime which is likely much slower. Furthermore, because of the resolution limit, the ratio of inhomogeneous broadening to homogeneous broadening for this transition has a lower bound of ~ 6 . This work was funded by NSF Grant DMR-1056860.

  9. Mechanism of frequency-dependent broadening of molluscan neurone soma spikes.

    PubMed

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

    1979-06-01

    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.

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

    PubMed

    Hlubek, M D; Cobbett, P

    2000-09-15

    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.

  11. Extraction of inhomogeneous broadening and nonradiative losses in InAs quantum-dot lasers

    SciTech Connect

    Chow, Weng W.; Liu, Alan Y.; Gossard, Arthur C.; Bowers, John E.

    2015-10-26

    We present a method to quantify inhomogeneous broadening and nonradiative losses in quantum dot lasers by comparing the gain and spontaneous emission results of a microscopic laser theory with measurements made on 1.3 μm InAs quantum-dot lasers. Calculated spontaneous-emission spectra are first matched to those measured experimentally to determine the inhomogeneous broadening in the experimental samples. This is possible because treatment of carrier scattering at the level of quantum kinetic equations provides the homogeneously broadened spectra without use of free parameters, such as the dephasing rate. We then extract the nonradiative recombination current associated with the quantum-dot active region from a comparison of measured and calculated gain versus current relations.

  12. Predict the pipeline buckling using the broadening factor of Brillouin spectrum width

    NASA Astrophysics Data System (ADS)

    Zhang, Chunshu; Bao, Xiaoyi; Ozkan, Istemi F.; Mohareb, Magdi; Ravet, Fabien; Zou, Lufan

    2007-06-01

    We monitored the distributed strain during the pipeline buckling process using distributed Brillouin sensor, which allows us to predict the buckling or crack location according to the sequence and location of the deformation for the first time using the broadening factor of Brillouin spectrum width. Two pipelines were designed and instrumented with polymer and carbon/polyimide coated fibers, and then the pipelines were subjected to internal pressure, axial tensile force and bending moment. We show that 1) the localized buckling occurred at the top, median and bottom of the pipeline, where the maximum broaden factors were obtained; 2) the deformation sequence can be measured using the nonlinearity of the broadening factor, 3) a high strength carbon/polyimide-coated fiber can detect higher stress accurately than standard telecom fibers. Our results strengthen the distributed Brillouin fiber sensor position as a nervous system to identify the potential problem in early stage for structural health monitoring.

  13. Positive emotions broaden the scope of attention and thought-action repertoires

    PubMed Central

    Fredrickson, Barbara L.; Branigan, Christine

    2011-01-01

    The broaden-and-build theory (Fredrickson, 1998, 2001) hypothesises that positive emotions broaden the scope of attention and thought-action repertoires. Two experiments with 104 college students tested these hypotheses. In each, participants viewed a film that elicited (a) amusement, (b) contentment, (c) neutrality, (d) anger, or (e) anxiety. Scope of attention was assessed using a global-local visual processing task (Experiment 1) and thought-action repertoires were assessed using a Twenty Statements Test (Experiment 2). Compared to a neutral state, positive emotions broadened the scope of attention in Experiment 1 and thought-action repertoires in Experiment 2. In Experiment 2, negative emotions, relative to a neutral state, narrowed thought-action repertoires. Implications for promoting emotional well-being and physical health are discussed. PMID:21852891

  14. He-broadening and shift coefficients of water vapor lines in infrared spectral region

    NASA Astrophysics Data System (ADS)

    Petrova, T. M.; Solodov, A. M.; Solodov, A. A.; Deichuli, V. M.; Starikov, V. I.

    2015-11-01

    The water vapor line broadening and shift coefficients in the ν1+ν2, ν2+ν3, ν1+ν3, 2ν3, 2ν1, 2ν2+ν3, and ν1+2ν2 vibrational bands induced by helium pressure were measured using a Bruker IFS 125HR spectrometer. The vibrational bands 2ν3 and ν1+2ν2 were investigated for the first time. The interaction potential used in the calculations of broadening and shift coefficients was chosen as the sum of pair potentials, which were modeled by the Lennard-Jones (6-12) potentials. The vibrational and rotational contributions to this potential were obtained by use of the intermolecular potential parameters and intramolecular parameters of H2O molecule. The calculated values of the broadening and shift coefficients were compared with the experimental data.

  15. Near and Far Wing Pressure Broadening Theory for Application to Atmospheric Absorption.

    DTIC Science & Technology

    1980-02-01

    WING CALCULATIONS OF 1120 PRESSURE BROADENING 23 3.1 Pressure Broadening of 1120 Transitions by P112 and Air 23 3.2 H20 Self-Broadening 25 4.0...terms of the two-body16/ T-matrix,--6 according to (CI-z) - I = (H0 -z) - (it 0 -z) T(z) (H0 -z)- , ( 25 ) where T(z) satisfies T :z) V - V(h0-z) -I T...z), (2) and 1* * T(z) T(z ). (27) Now from Eqs. (23), ( 25 ) we obtain 6(H-L) 6(H 0 -E) 1 +)-i - {(1 0-E-io T(E+io+) (H -E-io + ) - - (H0-E+io +- I T(E

  16. Collisional broadening of rotational lines in the stimulated Raman pentad Q-branch of CD4

    NASA Technical Reports Server (NTRS)

    Millot, G.; Lavorel, B.; Steinfeld, J. I.

    1992-01-01

    Self- and argon-broadening coefficients are reported for a number of Raman Q-branch transitions in the nu(1) and nu(2) + nu(4) bands of (C-12)D4 at room temperature (296 K). The coefficients display a variation with j and with C exp n (symmetry species A, E, F) that is essentially independent of collision partner and which is similar to the j- and C exp n-dependence found in previous measurements of the IR line-broadening coefficients. The rotationally inelastic collision rates previously measured by Foy et al. (1988) for (C-13)D4 (V4 = 0, 1) in collision with (C-13)D4 or Ar account for only a part of the Raman broadening rate, suggesting possibly significant contributions to the linewidths from efficient V-V transfer or elastic dephasing collisions.

  17. The broadened-specification fuels combustion technology program at Pratt and Whitney Aircraft

    NASA Technical Reports Server (NTRS)

    Lohmann, R. P.

    1980-01-01

    The impact of the use of broadened specification fuels on combustor design was investigated. Particular emphasis was placed on establishing the viability of various combustor modifications to permit the use of broadened specification fuels while meeting exhaust emissions and performance specifications and maintaining acceptable combustor operational and durability characteristics. Three different combustor concepts will be evaluated. Various design modifications on the operating capability of each of the combustor concepts with experimental referee broadened specification Fuel. The modifications that were evaluated included perturbations of the combustor airflow schedules to alter local stoichiometry and residence time histories revisions to the fuel injectors, and variations in liner cooling including the use of thermal barrier coatings and/or advanced cooling concepts.

  18. Spectral broadening in lithium niobate in a self-diffraction geometry using ultrashort pulses

    NASA Astrophysics Data System (ADS)

    Dharmadhikari, Jayashree A.; Dota, Krithika; Mathur, Deepak; Dharmadhikari, Aditya K.

    2016-05-01

    We report on broadband light generation in the impulsive regime in an un-doped lithium niobate (LiNbO3) crystal by two femtosecond laser pulses (36 fs) from a Ti-sapphire laser amplifier. We systematically investigate the role of incident intensity on spectral broadening. At relatively low incident intensity (0.7 TW cm-2), spectral broadening in the transmitted beam occurs due to the combined effect of self-phase modulation and cross-phase modulation. At higher incident intensity (10.2 TW cm-2), we observe generation of as many as 21 anti-Stokes orders due to coherent anti-Stokes Raman scattering in self-diffraction geometry. Moreover, we observe order-dependent spectral broadening of anti-Stokes lines that may be attributed to the competition with other nonlinear optical effects like cross-phase modulation.

  19. Influence of Rayleigh-Doppler broadening on the selection of H2O dial system parameters

    NASA Technical Reports Server (NTRS)

    Ismail, S.; Browell, E. V.

    1986-01-01

    Computer simulations have enabled the performance of a H2O Differential Absorption Lidar (DIAL) system to be studied by spectrally analyzing the forward propagating and backscattered laser energy. The simulations were done for a high altitude (21 km) DIAL system operating in a nadir-viewing mode. The influence of Rayleigh Doppler broadening on DIAL measurement accuracies were evaluated and show that the Rayleigh broadening influence, which can be corrected to first order in regions free of large aerosol gradients, reduces the sensitivity of DIAL H2O measurement errors in the upper tropospheric region. The ability to correct the Rayleigh broadening and the selection of H2O DIAL parameters when all the systematic effects are combined, were discussed.

  20. Modal dispersion, pulse broadening and maximum transmission rate in GRIN optical fibers encompass a central dip in the core index profile

    NASA Astrophysics Data System (ADS)

    El-Diasty, Fouad; El-Hennawi, H. A.; El-Ghandoor, H.; Soliman, Mona A.

    2013-12-01

    Intermodal and intramodal dispersions signify one of the problems in graded-index multi-mode optical fibers (GRIN) used for LAN communication systems and for sensing applications. A central index dip (depression) in the profile of core refractive-index may occur due to the CVD fabrication processes. The index dip may also be intentionally designed to broaden the fundamental mode field profile toward a plateau-like distribution, which have advantages for fiber-source connections, fiber amplifiers and self-imaging applications. Effect of core central index dip on the propagation parameters of GRIN fiber, such as intermodal dispersion, intramodal dispersion and root-mean-square broadening, is investigated. The conventional methods usually study optical signal propagation in optical fiber in terms of mode characteristics and the number of modes, but in this work multiple-beam Fizeau interferometry is proposed as an inductive but alternative methodology to afford a radial approach to determine dispersion, pulse broadening and maximum transmission rate in GRIN optical fiber having a central index dip.

  1. Nitrogen-broadened lineshapes in the oxygen A-band: Experimental results and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, Adriana; Holladay, Christopher; Heung, Henry; Bouanich, Jean-Pierre; Mellau, Georg Ch.; Keller, Reimund; Hurtmans, Daniel R.

    2008-09-01

    We report measurements for N 2-broadening, pressure-shift and line mixing coefficients for 55 oxygen transitions in the A-band retrieved using a multispectrum fitting technique. Nineteen laboratory absorption spectra were recorded at 0.02 cm -1 resolution using a multi-pass absorption cell with path length of 1636.9 cm and the IFS 120 Fourier transform spectrometer located at Justus-Liebig-University in Giessen, Germany. The total sample pressures ranged from 8.8 to 3004.5 Torr with oxygen volume mixing ratios in nitrogen ranging between 0.057 and 0.62. An Exponential Power Gap (EPG) scaling law was used to calculate the N 2-broadening and N 2-line mixing coefficients. The line broadening and shift coefficients for the A-band of oxygen self-perturbed and perturbed by N 2 are modeled using semiclassical calculations based on the Robert-Bonamy formalism and two intermolecular potentials. These potentials involve electrostatic contributions including the hexadecapole moment of the molecules and (a) a simple dispersion contribution with one adjustable parameter to fit the broadening coefficients or (b) the atom-atom Lennard-Jones model without such adjustable parameters. The first potential leads to very weak broadening coefficients for high J transitions whereas the second potential gives much more improved results at medium and large J values, in reasonable agreement with the experimental data. For the line shifts which mainly arise in our calculation from the electronic state dependence of the isotropic potential, their general trends with increasing J values can be well predicted, especially from the first potential. From the theoretical results, we have derived air-broadening and air-induced shift coefficients with an agreement comparable to that obtained for O 2-O 2 and O 2-N 2.

  2. Experimental air-broadened line parameters in the nu(2) band of CH3D

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, Adriana; Brawley-Tremblay, Shannon; Povey, Chad; Smith, Mary Ann H.

    2007-02-01

    In this study, we report the first experimental measurements of air-broadening and air-induced pressure-shift coefficients for approximately 378 transitions in the nu(2) fundamental band of CH3D. These results were obtained from analysis of 17 room-temperature laboratory absorption spectra recorded at 0.0056 cm(-1) resolution using the McMath-Pierce Fourier transform spectrometer located on Kitt Peak, Ariz. Three absorption cells with path lengths of 10.2, 25, and 150 cm were used to record the spectra. The total sample pressures ranged from 0.129 x 10(-2) to 52.855 x 10(-2) atm with CH3D volume mixing ratios of approximately 0.0109 in air. The spectra were analyzed using a multispectrum nonlinear least-squares fitting technique. We report measurements for air pressure-broadening coefficients for transitions with quantum numbers as high as J'' D 20 and K D 15, where K'' D K' equivalent to K (for a parallel band). The measured air-broadening coefficients range from 0.0205 to 0.0835 cm(-1)atm(-1) at 296 K. All the measured pressure-shift coefficients are negative and are found to vary from about -0.0005 to -0.0080 cm(-1) atm(-1) at the temperature of the spectra. We have examined the dependence of the measured broadening and shift parameters on the J'', and K quantum numbers and also developed empirical expressions to describe the broadening coefficients in terms of m (m D -J'', J'', and J'' + 1 in the P-Q-, (Q)Q-, and R-Q-branch, respectively) and K. On average, the empirical expressions reproduce the measured broadening coefficients to within 4.4%.

  3. Pressure broadening of atomic oxygen two-photon absorption laser induced fluorescence

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  4. Why Is Non-thermal Line Broadening of Lower Transition Region Lines Independent of Spatial Resolution?

    NASA Astrophysics Data System (ADS)

    De Pontieu, B.; Mcintosh, S. W.; Martínez-Sykora, J.; Peter, H.; Pereira, T. M. D.

    2014-12-01

    Spectral observations of the solar transition region (TR) and corona typically show broadening of the spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant (10-30 km/s), correlated with the intensity, and has been attributed to waves, macro and micro turbulence, nanoflares, etc... Here we study spectra of the low TR Si IV 1403 Angstrom line obtained at high spatial and spectral resolution with the Interface Region Imaging Spectrograph (IRIS). We find that the large improvement in spatial resolution (0.33 arcsec) of IRIS compared to previous spectrographs (2 arcsec) does not resolve the non-thermal line broadening which remains at pre-IRIS levels of 20 km/s. This surprising invariance to spatial resolution indicates that the physical processes behind the non-thermal line broadening either occur along the line-of-sight (LOS) and/or on spatial scales (perpendicular to the LOS) smaller than 250 km. Both effects appear to play a role. Comparison with IRIS chromospheric observations shows that, in regions where the LOS is more parallel to the field, magneto-acoustic shocks driven from below impact the low TR leading to strong non-thermal line broadening from line-of-sight integration across the shock at the time of impact. This scenario is confirmed by advanced MHD simulations. In regions where the LOS is perpendicular to the field, the prevalence of small-scale twist is likely to play a significant role in explaining the invariance and the correlation with intensity.

  5. Experimental Air-Broadened Line Parameters in the nu2 Band of CH3D

    NASA Technical Reports Server (NTRS)

    Cross, Adriana Predoi; Brawley-Tremblay, Shannon; Povey, Chad; Smith, Mary Ann H.

    2007-01-01

    In this study we report the first experimental measurements of air-broadening and air-induced pressure-shift coefficients for approximately 378 transitions in the nu2 fundamental band of CH3D. These results were obtained from analysis of 17 room temperature laboratory absorption spectra recorded at 0.0056 cm(exp -1) resolution using the McMath-Pierce Fourier transform spectrometer located on Kitt Peak, Arizona. Three absorption cells with path lengths of 10.2, 25 and 150 cm were used to record the spectra. The total sample pressures ranged from 0.129x10(exp -2) to 52.855x10(exp -2) atm with CH3D volume mixing ratios of approximately 0.0109 in air. The spectra were analyzed using a multispectrum non-linear least-squares fitting technique. We report measurements for air pressure-broadening coefficients for transitions with quantum numbers as high as J" = 20 and K = 15, where K" = K' equivalent to K (for a parallel band). The measured air broadening coefficients range from 0.0205 to 0.0835 cm(exp -1) atm(exp -1) at 296 K. All the measured pressure-shift coefficients are negative and are found to vary from about -0.0005 to -0.0080 cm(exp -1) atm(exp -1) at the temperature of the spectra. We have examined the dependence of the measured broadening and shift parameters on the J" and K quantum numbers and also developed empirical expressions to describe the broadening coefficients in terms of m (m = -J", J" and J" + 1 in the (sup Q)P- (sup Q)Q-, and (sup Q)R-branch, respectively) and K. On average, the empirical expressions reproduce the measured broadening coefficients to within 4.4%.

  6. Broadening our approaches to studying dispersal in raptors

    USGS Publications Warehouse

    Morrison, J.L.; Wood, P.B.

    2009-01-01

    Dispersal is a behavioral process having consequences for individual fitness and population dynamics. Recent advances in technology have spawned new theoretical examinations and empirical studies of the dispersal process in birds, providing opportunities for examining how this information may be applied to studies of the dispersal process in raptors. Many raptors are the focus of conservation efforts; thus, reliable data on all aspects of a species' population dynamics, including dispersal distances, movement rates, and mortality rates of dispersers, are required for population viability analyses that are increasingly used to inform management. Here, we address emerging issues and novel approaches used in the study of avian dispersal, and provide suggestions to consider when developing and implementing studies of dispersal in raptors. Clarifying study objectives is essential for selection of an appropriate methodology and sample size needed to obtain accurate estimates of movement distances and rates. Identifying an appropriate study-area size will allow investigators to avoid underestimating population connectivity and important population parameters. Because nomadic individuals of some species use temporary settling areas or home ranges before breeding, identification of these areas is critical for conservation efforts focusing on habitats other than breeding sites. Study designs for investigating raptor dispersal also should include analysis of environmental and social factors influencing dispersal, to improve our understanding of condition-dependent dispersal strategies. Finally, we propose a terminology for use in describing the variety of movements associated with dispersal behavior in raptors, and we suggest this terminology could be used consistently to facilitate comparisons among studies. ?? 2009 The Raptor Research Foundation, Inc.

  7. Origin of asymmetric broadening of Raman peak profiles in Si nanocrystals

    PubMed Central

    Gao, Yukun; Yin, Penggang

    2017-01-01

    The asymmetric peak broadening towards the low-frequency side of the Raman-active mode of Si nanocrystals with the decreasing size has been extensively reported in the literatures. In this study, an atomic coordination model is developed to study the origin of the ubiquitous asymmetric peak on the optical phonon fundamental in the Raman spectra of Si nanocrystals. Our calculation results accurately replicate the line shape of the experimentally measured optical Raman curves. More importantly, it is revealed that the observed asymmetric broadening is mainly caused by the surface bond contraction and the quantum confinement. PMID:28240325

  8. On spectral line Stark broadening parameters needed for stellar and laboratory plasma investigations.

    NASA Astrophysics Data System (ADS)

    Dimitrijević, M. S.

    1995-03-01

    This paper presents a review of semiclassical calculations of Stark broadening parameters and a comparison of different semiclassical procedures is discussed, as well as the agreement with critically selected experimental data and more sophisticated, close coupling calculations. Approximate methods for the calculation of Stark broadening parameters, useful especially in such astrophysical problems where large scale calculations and analyses must be performed and where a good average accuracy is expected, have also been discussed. The beginning and development of line shapes investigations in Yugoslavia has been described as well.

  9. Surface anchoring effects on spectral broadening of cholesteric liquid crystal films

    SciTech Connect

    Fan, B.; Vartak, S.; Eakin, J. N.; Faris, S. M.

    2008-07-15

    This paper describes the spectral broadening of cholesteric liquid crystal film prepared from a blend comprising a cross-linkable liquid crystal polymer and a non-cross-linkable low-molecular-weight liquid crystal. The spectral broadening arises from the formation of gradient pitch across the film thickness. It is shown that both phase-separation and in situ swelling during photopolymerization are important mechanisms for the resulting film structure. The surface anchoring is important to achieve high wavelength- and polarization-selective reflectance.

  10. Experimental transition probabilities and Stark-broadening parameters of neutral and single ionized tin

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1979-01-01

    Strengths and Stark-effect widths of the Sn I and Sn II lines prominent between 3200 and 7900 A are measured with a spectroscopic shock tube. Absolute strengths of 17 ionic lines are obtained with estimated (22-50)% accuracy and conform to appropriate quantum-mechanical sum rules. Relative transition probabilities for nine prominent neutral tin lines, normalized to radiative-lifetime data, are compared with other experiments and theoretical predictions. Parameters for Stark-effect broadening are measured over a range of plasma electron densities. Broadening data (with accuracies of 15-35%) for one neutral and ten ionic lines of tin are compared to theoretical predictions.

  11. Broadening of the spectral lines of a buffer gas and target substance in laser ablation

    SciTech Connect

    Kask, Nikolai E; Michurin, Sergei V

    2012-11-30

    The broadening of discrete spectral lines from the plasma produced in the laser ablation of metal targets in a broad pressure range (10{sup 2} - 10{sup 7} Pa) of the ambient gas (Ar, He, H{sub 2}) was studied experimentally. The behaviour of spectral line broadening for the buffer gases was found to be significantly different from that for the atoms and ions of the target material. In comparison with target atoms, the atoms of buffer gases radiate from denser plasma layers, and their spectral line profiles are complex in shape. (interaction of laser radiation with matter. laser plasma)

  12. Measurement of self-broadening of the ozone nu(3) transitions

    NASA Technical Reports Server (NTRS)

    Flannery, C.; Klaassen, J. J.; Gojer, M.; Steinfeld, J. I.; Spencer, M.; Chackerian, C., Jr.

    1991-01-01

    Self-broadening coefficients have been measured for a number of rovibrational lines in the nu(3) band of ozone, in the frequency range 1015-1058/cm, with J values between 0 and 27, and over a range of K(a) values. A multiparameter nonlinear least-squares fitting procedure is used to reduce the data, and the sensitivity of the procedure to instrument line width, weak satellite features, and absolute intensity has been examined. The retrieved coefficients are compared with millimeter-wave broadening coefficients, direclty measured rotational relaxation times, and recently suggested empirical representations.

  13. Broadening and shift of the spectral lines of hydrogen atoms and silicon ions in laser plasma

    SciTech Connect

    Kask, N E; Leksina, E G; Michurin, S V; Fedorov, G M; Chopornyak, D B

    2015-06-30

    We report an experimental investigation of the broadening and shift of discrete lines in the plasma spectrum produced in the laser ablation of silicon in a broad pressure range (10{sup 2} – 10{sup 7} Pa) of the ambient gas (Ar, He, H{sub 2}). The broadening and line shifts are measured in relation to the distance from the target and initial gas pressure. The threshold nature of the resulting dependences is found to be related to the formation of virtual percolation clusters proceeding in the hot dense plasma. (laser plasma)

  14. Covariance Matrix of a Double-Differential Doppler-broadened Elastic Scattering Cross Section

    SciTech Connect

    Arbanas, Goran; Becker, B.; Dagan, R; Dunn, Michael E; Larson, Nancy M; Leal, Luiz C; Williams, Mark L

    2012-01-01

    Legendre moments of a double-differential Doppler-broadened elastic neutron scattering cross section on {sup 238}U are computed near the 6.67 eV resonance at temperature T = 10{sup 3} K up to angular order 14. A covariance matrix of these Legendre moments is computed as a functional of the covariance matrix of the elastic scattering cross section. A variance of double-differential Doppler-broadened elastic scattering cross section is computed from the covariance of Legendre moments.

  15. Helium broadened propane absorption cross sections in the far-IR

    NASA Astrophysics Data System (ADS)

    Wong, A.; Billinghurst, B.; Bernath, P. F.

    2017-09-01

    Infrared absorption spectra for pure and He broadened propane have been recorded in the far-IR region (650-1300 cm-1) at the Canadian Light Source (CLS) facility using either the synchrotron or internal glowbar source depending on the required resolution. The measurements were made for 4 temperatures in the range 202-292 K and for 3 pressures of He broadening gas up to 100 Torr. Infrared absorption cross sections are derived from the spectra and the integrated cross sections are within 10 % of the corresponding values from the Pacific Northwest National Laboratory (PNNL) for all temperatures and pressures.

  16. Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

    PubMed

    Peled, Itay; Kaminsky, Ron; Kotler, Zvi

    2015-06-01

    In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.

  17. Dynamic broadening of the crystal-fluid interface of colloidal hard spheres.

    PubMed

    Dullens, Roel P A; Aarts, Dirk G A L; Kegel, Willem K

    2006-12-01

    We investigate the structure and dynamics of the crystal-fluid interface of colloidal hard spheres in real space by confocal microscopy. Tuning the buoyancy of the particles allows us to study the interface close to and away from equilibrium. We find that the interface broadens from 8-9 particle diameters close to equilibrium to 15 particle diameters away from equilibrium. Furthermore, the interfacial velocity, i.e., the velocity by which the interface moves upwards, increases significantly. The increasing gravitational drive leads to supersaturation of the fluid above the crystal surface. This dramatically affects crystal nucleation and growth, resulting in the observed dynamic broadening of the crystal-fluid interface.

  18. Stark broadening experiments on a vacuum arc discharge in tin vapor.

    PubMed

    Kieft, E R; van der Mullen, J J A M; Kroesen, G M W; Banine, V; Koshelev, K N

    2004-12-01

    Pinched discharge plasmas in tin vapor are candidates for application in future semiconductor lithography tools. This paper presents time-resolved measurements of Stark broadened linewidths in a pulsed tin discharge. Stark broadening parameters have been determined for four lines of the Sn III spectrum in the range from 522 to 538 nm, based on a cross-calibration to a Sn II line with a previously known Stark width. The influence of the electron temperature on the Stark widths is discussed. Results for the electron densities in the discharge are presented and compared to Thomson scattering results.

  19. Measurement of self-broadening of the ozone nu(3) transitions

    NASA Technical Reports Server (NTRS)

    Flannery, C.; Klaassen, J. J.; Gojer, M.; Steinfeld, J. I.; Spencer, M.; Chackerian, C., Jr.

    1991-01-01

    Self-broadening coefficients have been measured for a number of rovibrational lines in the nu(3) band of ozone, in the frequency range 1015-1058/cm, with J values between 0 and 27, and over a range of K(a) values. A multiparameter nonlinear least-squares fitting procedure is used to reduce the data, and the sensitivity of the procedure to instrument line width, weak satellite features, and absolute intensity has been examined. The retrieved coefficients are compared with millimeter-wave broadening coefficients, direclty measured rotational relaxation times, and recently suggested empirical representations.

  20. Pressure broadening of vibrational Raman lines in N2 at temperatures below 300 K

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; South, B. W.

    1994-01-01

    Using quasi-cw stimulated Raman gain spectroscopy, the pressure broadening coefficients for the N2 vibrational Q-branch transitions have been measured over the temperature range 113-297 K for the rotational components J = 4, 6, 8, 10, and 12. The experimental results are fit to a simple power law to give an empirical formula for the temperature dependence of the pressure broadening over the 100-300 K range. These results are also compared to previously published scaling laws that are based on collision induced rotational transition rates.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  2. Collisional Shift and Broadening of Iodine Spectral Lines in Air Near 543 nm

    NASA Technical Reports Server (NTRS)

    Fletcher, D. G.; McDaniel, J. C.

    1995-01-01

    The collisional processes that influence the absorption of monochromatic light by iodine in air have been investigated. Measurements were made in both a static cell and an underexpanded jet flow over the range of properties encountered in typical compressible-flow aerodynamic applications. Experimentally measured values of the collisional shift and broadening coefficients were 0.058 +/- 0.004 and 0.53 +/- 0.010 GHz K(exp 0.7)/torr, respectively. The measured shift value showed reasonable agreement with theoretical calculations based on Lindholm-Foley collisional theory for a simple dispersive potential. The measured collisional broadening showed less favorable agreement with the calculated value.

  3. Argon-broadened line parameters in the ν3 band of 12CH4.

    NASA Astrophysics Data System (ADS)

    Gabard, T.

    1997-02-01

    Prompted by improved measurements of collisional line shapes in the ν3 band P, Q and R branches of 12CH4, The author has performed semi-classical line broadening calculations for methane perturbed by argon. He has used the theoretical approach developed by Robert and Bonamy (1979) as an extension of the well-known Anderson-Tsao-Curnutte theory. The semi-classical theory as reformulated here is shown to fully account for the tetrahedral symmetry of methane type molecules. The variation of argon-broadened linewidth coefficients in the ν3 band of 12CH4 with the branch, J, symmetry and energy level fine structure is discussed.

  4. Origin of asymmetric broadening of Raman peak profiles in Si nanocrystals

    NASA Astrophysics Data System (ADS)

    Gao, Yukun; Yin, Penggang

    2017-02-01

    The asymmetric peak broadening towards the low-frequency side of the Raman-active mode of Si nanocrystals with the decreasing size has been extensively reported in the literatures. In this study, an atomic coordination model is developed to study the origin of the ubiquitous asymmetric peak on the optical phonon fundamental in the Raman spectra of Si nanocrystals. Our calculation results accurately replicate the line shape of the experimentally measured optical Raman curves. More importantly, it is revealed that the observed asymmetric broadening is mainly caused by the surface bond contraction and the quantum confinement.

  5. Envelope broadening and scattering attenuation of a scalar wavelet in random media having power-law spectra

    NASA Astrophysics Data System (ADS)

    Sato, Haruo

    2016-01-01

    frequency independent, and scattering attenuation is weak. When the random medium power spectra have a small role-off, however, the envelope broadening is large and increases with frequency, and the scattering attenuation is strong and increases with frequency. The proposed synthesis of MS envelopes is fully analytic; therefore, it can be a theoretical basis for the evaluation of random heterogeneity of the earth medium from the analysis of seismogram envelopes.

  6. Line intensities and collisional-broadening parameters for the nu4 and nu6 bands of carbonyl fluoride

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1992-01-01

    Line intensities, air- and self-broadening parameters have been measured for selected lines in the nu4 (1243/cm) and nu6 (774/cm) bands of carbonyl fluoride at 296 and 215 K using a tunable diode-laser spectrometer. Measured line intensities are in good agreement +/- 6 percent with recently reported values derived from rotational analyses of the nu4 and nu6 bands. The measured average air-broadening coefficient at 296 K also agrees well (+/- 5 percent) with N2-broadening coefficients determined from microwave studies, while the average self-broadening coefficient reported here is smaller than a previously reported value by 45 percent.

  7. Attitudes and Motivation of Poor and Good Spellers: Broadening Planned Behavior Theory

    ERIC Educational Resources Information Center

    Sideridis, Georgios D.

    2005-01-01

    The purpose of the present study was to broaden planned behavior theory and examine its applicability to predict the academic achievement of students of low and high spelling ability. Two hundred fifty seven students, 54 low spellers and 203 high spellers from thirty elementary schools in northern Greece, participated in the study. Between groups…

  8. Improved electron collisional line broadening for low-temperature ions and neutrals in plasma modeling

    DOE PAGES

    Johns, H. M.; Kilcrease, D. P.; Colgan, J.; ...

    2015-09-29

    In this study, electron collisional broadening of observed spectral lines depends on plasma electron temperature and density. Including this effect in models of measured spectra is necessary to determine plasma conditions; however, computational limits make accurate line broadening treatments difficult to implement in large-scale plasma modeling efforts. In this paper, we report on improvements to the treatment of electron collisional line broadening and illustrate this with calculations using the Los Alamos ATOMIC code. We implement the Dimitrijevic and Konjevic modified semi-empirical model Dimitrijevic and Konjevic (1986 Astron. and Astrophy. 163 297 and 1987 Astron. Astrophys. 172 345), which we amendmore » by employing oscillator strengths from Hartree–Fock calculations. This line broadening model applies to near-neutral plasmas with electron temperatures of Te ~ 1 eV and electron densities of Ne ~1017 cm-3. We evaluate the D.K.-inspired model against the previous hydrogenic approach in ATOMIC through comparison to NIST-rated measurements for selected neutral and singly-ionized Ca, O, Fe, and Sn lines using both fine-structure and configuration-averaged oscillator strengths. The new D.K.-inspired model is significantly more accurate than the previous hydrogenic model and we find the use of configuration-averaged oscillator strengths a good approximation for applications such as LIBS (laser induced breakdown spectroscopy), for which we demonstrate the use of the D.K.-inspired model.« less

  9. Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD+ ions

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    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.

  10. Improving Enzyme Activity and Broadening Selectivity for Biological Desulfurization and Upgrading of Petroleum Feedstocks

    SciTech Connect

    Abhijeet P. Borole; Choo Y. Hamilton; Karen Miller; Brian Davison; Matthew Grossman; Robert Shong

    2003-05-12

    The objective of this project was to develop improved biocatalysts for desulfurization and upgrading of petroleum feedstocks. The goal was to improve the activity and broaden the selectivity of desulfurization enzymes using directed evolution as a tool as well as to explore the impact of ring-opening on biological desulfurization

  11. Proton disorder in ice Ih and inhomogeneous broadening in two-dimensional infrared spectroscopy.

    PubMed

    Shi, L; Skinner, J L

    2013-12-12

    It is well-known that in ice Ih the oxygen atoms form a regular hexagonal lattice while the positions of the hydrogen atoms are disordered, called proton disorder in the literature. Various OH (OD) stretch vibrational spectroscopies (e.g., IR, Raman, two-dimensional IR (2DIR), and hole burning) have been used to probe this proton disorder in the past several decades. However, the presence and the magnitude of the inhomogeneous broadening due to this proton disorder in the vibrational spectroscopy is still controversial. In this work, we calculate 2DIR spectroscopy for HOD in D2O ice Ih at 80 K with a mixed quantum/classical approach, and make comparison to a recent 2DIR experiment on the same system. Fair agreement is achieved between theory and experiment, although the calculated 2DIR line shape shows inhomogeneous broadening that was not observed in the experiment. However, the theory reproduces the linear IR for the same system fairly well, and the inhomogeneous broadening from the calculation is consistent with the extrapolation of the experimental IR line-widths in the literature. The effect of this proton disorder on the 2DIR line shape is explored in detail. We also calculate the vibrational three-pulse photon echo peak shift signal, which shows signatures of both low-frequency dynamics and inhomogeneous broadening.

  12. Broadening Educational Outcomes: Social Relations, Skills Development, and Employability for Youth

    ERIC Educational Resources Information Center

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

    2016-01-01

    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. An Experiment to Demonstrate the Energy Broadening of Annihilation Gamma Rays

    ERIC Educational Resources Information Center

    Ouseph, P. J.; DuBard, James L.

    1978-01-01

    Shows that when positions annihilate in solid materials the energy distribution of the annihilation gamma rays is much broader than that of a 0.511-Mev gamma peak. This broadening is caused by the momentum distribution of the electrons in the material. (Author/GA)

  14. Wideband nonlinear spectral broadening in ultra-short ultra - silicon rich nitride waveguides

    PubMed Central

    Choi, Ju Won; Chen, George F. R.; Ng, D. K. T.; Ooi, Kelvin J. A.; Tan, Dawn T. H.

    2016-01-01

    CMOS-compatible nonlinear optics platforms with high Kerr nonlinearity facilitate the generation of broadband spectra based on self-phase modulation. Our ultra – silicon rich nitride (USRN) platform is designed to have a large nonlinear refractive index and low nonlinear losses at 1.55 μm for the facilitation of wideband spectral broadening. We investigate the ultrafast spectral characteristics of USRN waveguides with 1-mm-length, which have high nonlinear parameters (γ ∼ 550 W−1/m) and anomalous dispersion at 1.55 μm wavelength of input light. USRN add-drop ring resonators broaden output spectra by a factor of 2 compared with the bandwidth of input fs laser with the highest quality factors of 11000 and 15000. Two – fold self phase modulation induced spectral broadening is observed using waveguides only 430 μm in length, whereas a quadrupling of the output bandwidth is observed with USRN waveguides with a 1-mm-length. A broadening factor of around 3 per 1 mm length is achieved in the USRN waveguides, a value which is comparatively larger than many other CMOS-compatible platforms. PMID:27272558

  15. Origins of spectral broadening of incoherent waves: Catastrophic process of coherence degradation

    NASA Astrophysics Data System (ADS)

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

    2017-08-01

    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.

  16. PULSE BROADENING MEASUREMENTS FROM THE GALACTIC CENTER PULSAR J1745-2900

    SciTech Connect

    Spitler, L. G.; Lee, K. J.; Eatough, R. P.; Kramer, M.; Karuppusamy, R.; Desvignes, G.; Champion, D. J.; Falcke, H.; Bassa, C. G.; Lyne, A. G.; Stappers, B. W.; Cognard, I.; Cordes, J. M.

    2014-01-01

    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.

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

    PubMed Central

    Taibbi, Giovanni; Wang, Zhong I; Dell’Osso, Louis F

    2008-01-01

    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 high-foveation-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. PMID:19668758

  18. An Experiment to Demonstrate the Energy Broadening of Annihilation Gamma Rays

    ERIC Educational Resources Information Center

    Ouseph, P. J.; DuBard, James L.

    1978-01-01

    Shows that when positions annihilate in solid materials the energy distribution of the annihilation gamma rays is much broader than that of a 0.511-Mev gamma peak. This broadening is caused by the momentum distribution of the electrons in the material. (Author/GA)

  19. Experimental Evidence of Edge Fluctuation Broadening of ECH Deposition at DIII-D

    NASA Astrophysics Data System (ADS)

    Brookman, M. W.; Austin, M. E.; Gentle, K. W.; Petty, C. C.; Peysson, Y.; Decker, J.; Barada, K.; Ernst, D. E.

    2016-10-01

    This work provides experimental evidence for broadening of the ECH and ECCD deposition by edge density fluctuations. Results on the DIII-D tokamak suggest a deposition FWHM 1.7-2.8 times wider than TORAY-GA. A 1D ECH deposition profile was measured through gyrotron power modulation. From 500 kHz, 48-channel ECE measurements and trial ECH deposition functions, a Fourier transformed heat flux is found and fit to transport drive terms. Radially broader ECH deposition best fit calculated fluxes in discharges with higher levels of edge density turbulence. Broadening of deposition does not arise from anomalous transport, which is minimal on DIII-D. Simulation and theory suggest edge (ρ.9) turbulent n _ e fluctuations refract RF waves that pass through them, broadening radial deposition of ECH and ECCD. On ITER, this effect could hinder NTM suppression by broadening ECCD deposition outside the 3/2 island. Work supported by the U.S. DOE under Award DE-FC02-04ER54698.

  20. Solitons and spectral broadening in long silicon-on- insulator photonic wires.

    PubMed

    Ding, W; Benton, C; Gorbach, A V; Wadsworth, W J; Knight, J C; Skryabin, D V; Gnan, M; Sorrel, M; De La Rue, R M

    2008-03-03

    We report measurements and numerical modeling of spectral broadening and soliton propagation regimes in silicon-on-insulator photonic wire waveguides of 3 to 4 dispersion lengths using 100fs pump pulses. We also present accurate measurements of the group index and dispersion of the photonic wire.

  1. Theoretical Studies of Laser-Induced Molecular Rate Processes: Topics in Line Broadening and Spectroscopy.

    DTIC Science & Technology

    1985-10-01

    GROUP SU. GRF. MOLECULAR RATE PROCESSES MOLECULAR DYNAMICS LASER-INDUCED LINE BROADENING THEORETICAL STUDIES SPECTROSCOPY 19. ABSI*ACT (Continue On...approaches half the band-gap energy. -q 14 This idea of using a laser to "charge" the surface region has fomed the basis of a semiclassical theory of charge

  2. PROBLEM DEPENDENT DOPPLER BROADENING OF CONTINUOUS ENERGY CROSS SECTIONS IN THE KENO MONTE CARLO COMPUTER CODE

    SciTech Connect

    Hart, S. W. D.; Maldonado, G. Ivan; Celik, Cihangir; Leal, Luiz C

    2014-01-01

    For many Monte Carlo codes cross sections are generally only created at a set of predetermined temperatures. This causes an increase in error as one moves further and further away from these temperatures in the Monte Carlo model. This paper discusses recent progress in the Scale Monte Carlo module KENO to create problem dependent, Doppler broadened, cross sections. Currently only broadening the 1D cross sections and probability tables is addressed. The approach uses a finite difference method to calculate the temperature dependent cross-sections for the 1D data, and a simple linear-logarithmic interpolation in the square root of temperature for the probability tables. Work is also ongoing to address broadening theS (alpha , beta) tables. With the current approach the temperature dependent cross sections are Doppler broadened before transport starts, and, for all but a few isotopes, the impact on cross section loading is negligible. Results can be compared with those obtained by using multigroup libraries, as KENO currently does interpolation on the multigroup cross sections to determine temperature dependent cross-sections. Current results compare favorably with these expected results.

  3. Broadening Educational Outcomes: Social Relations, Skills Development, and Employability for Youth

    ERIC Educational Resources Information Center

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

    2016-01-01

    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…

  4. Band-broadening in capillary zone electrophoresis with axial temperature gradients.

    PubMed

    Xuan, Xiangchun; Li, Dongqing

    2005-01-01

    It is widely accepted that Joule heating effects yield radial temperature gradients in capillary zone electrophoresis (CZE). The resultant parabolic profile of electrophoretic velocity of analyte molecules is believed to increase the band-broadening via Taylor-Aris dispersion. This typically insignificant contribution, however, cannot explain the decrease in separation efficiency at high electric fields. We show that the additional band-broadening due to axial temperature gradients may provide the answer. These axial temperature variations result from the change of heat transfer condition along the capillary, which is often present in CZE with thermostating. In this case, the electric field becomes nonuniform due to the temperature dependence of fluid conductivity, and hence the induced pressure gradient is brought about to meet the mass continuity. This modification of the electroosmotic flow pattern can cause significant band-broadening. An analytical model is developed to predict the band-broadening in CZE with axial temperature gradients in terms of the theoretical plate height. We find that the resultant thermal plate height can be very high and even comparable to that due to molecular diffusion. This thermal plate height is much higher than that due to radial temperature gradients alone. The analytical model explains successfully the phenomena observed in previous experiments.

  5. An Assessment of Air Force Civil Engineering Officer Perceptions of Assignments to Career Broadening Positions.

    DTIC Science & Technology

    1986-09-01

    effort to study the important variable of organizational commitment. Steers developed and tested a model concerning employee commitment to organizations...where they can use their skills and satisfy personal needs and desires. Employee commitment is enhanced in organizations that satisfy these requirements...to remain, and achievement opportunities increase, employee commitment to the organization increases. Career Broadening in General There were

  6. cSELF (Computer Science Education from Life): Broadening Participation through Design Agency

    ERIC Educational Resources Information Center

    Bennett, Audrey; Eglash, Ron

    2013-01-01

    The phrase "broadening participation" is often used to describe efforts to decrease the race and gender gap in science and engineering education, and in this paper the authors describe an educational program focused on addressing the lower achievement rates and career interests of underrepresented ethnic groups (African American, Native…

  7. Excessive broadening of hydrogen Balmer lines for discharge-surface interaction monitoring

    SciTech Connect

    Konjevic, N.; Majstorovic, G. Lj.; Sisovic, N.M.

    2005-06-20

    A comparative study of the hydrogen H{sub {alpha}} line shapes in titanium and stainless steel hollow cathode discharges, run with hydrogen or argon-hydrogen mixture illustrates the possibility of using the excessively broadened part of line profile for heavy particle-cathode surface interaction monitoring.

  8. Visual observations of macroscopic inhomogeneous broadening of the R1 line in ruby

    NASA Astrophysics Data System (ADS)

    Jessop, P. E.; Szabo, A.

    1980-09-01

    Observation of sharp spatial variations of the R1 fluorescence of ruby at 5 K resonantly excited by a 1-MHz-linewidth scanning cw dye laser indicates the presence of gross macroscopic strain broadening in Czochralski and Verneuil crystals. The implications of these results in several current studies are discussed.

  9. High Temporal and Spatial Resolution Electron Density Diagnostic for the Edge Plasma based on Stark Broadening

    NASA Astrophysics Data System (ADS)

    Zafar, Abdullah; Martin, Elijah; Shannon, Steve; Isler, Ralph; Caughman, John

    2016-10-01

    Passive spectroscopic measurements of Stark broadening have been reliably used to determine electron density for decades. However, a low-density limit ( 1014 cm-3) exists due to Doppler and instrument broadening of the spectral line profile. A synthetic electron density diagnostic capable of high temporal (ms) and spatial (mm) resolution is currently under development at Oak Ridge National Laboratory. The diagnostic is based on measuring the Stark broadened, Doppler-free, spectral line profile of a Balmar series transition by using an active laser based technique. The diagnostic approach outlined here greatly reduces both of these broadening contributions using Doppler-free saturation spectroscopy (DFSS), allowing access to lower density regimes. The measured profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The modeling and experimental results for this active spectroscopic technique are presented for a magnetized (<=5 T), low-density (1011-1013 cm-3) plasma. Details of applying DFSS to the plasma edge are also discussed.

  10. Second harmonic generation of spectrally broadened femtosecond ytterbium laser radiation in a gas-filled capillary

    SciTech Connect

    Didenko, N V; Konyashchenko, Aleksandr V; Kostryukov, P V; Losev, Leonid L; Tenyakov, S Yu

    2011-09-30

    A 300-fs radiation pulse of an ytterbium laser with a wavelength of 1030 nm and energy of 150 {mu}J were converted to a 15-fs pulse with a wavelength of 515 nm by broadening the emission spectrum in a capillary filled with xenon and by generating the second harmonic in a KDP crystal. The energy efficiency of the conversion was 30 %.

  11. Deconvolving instrumental and intrinsic broadening in core-shell x-ray spectroscopies

    SciTech Connect

    Fister, T. T.; Seidler, G. T.; Rehr, J. J.; Kas, J. J.; Nagle, K. P.; Elam, W. T.; Cross, J. O.

    2007-05-01

    Intrinsic and experimental mechanisms frequently lead to broadening of spectral features in core-shell spectroscopies. For example, intrinsic broadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy elements where the core-hole lifetime is very short. On the other hand, nonresonant x-ray Raman scattering (XRS) and other energy loss measurements are more limited by instrumental resolution. Here, we demonstrate that the Richardson-Lucy (RL) iterative algorithm provides a robust method for deconvolving instrumental and intrinsic resolutions from typical XAS and XRS data. For the K-edge XAS of Ag, we find nearly complete removal of {approx}9.3 eV full width at half maximum broadening from the combined effects of the short core-hole lifetime and instrumental resolution. We are also able to remove nearly all instrumental broadening in an XRS measurement of diamond, with the resulting improved spectrum comparing favorably with prior soft x-ray XAS measurements. We present a practical methodology for implementing the RL algorithm in these problems, emphasizing the importance of testing for stability of the deconvolution process against noise amplification, perturbations in the initial spectra, and uncertainties in the core-hole lifetime.

  12. Improved electron collisional line broadening for low-temperature ions and neutrals in plasma modeling

    SciTech Connect

    Johns, H. M.; Kilcrease, D. P.; Colgan, J.; Judge, E. J.; Barefield II, J. E.; Wiens, R. C.; Clegg, S. M.

    2015-09-29

    In this study, electron collisional broadening of observed spectral lines depends on plasma electron temperature and density. Including this effect in models of measured spectra is necessary to determine plasma conditions; however, computational limits make accurate line broadening treatments difficult to implement in large-scale plasma modeling efforts. In this paper, we report on improvements to the treatment of electron collisional line broadening and illustrate this with calculations using the Los Alamos ATOMIC code. We implement the Dimitrijevic and Konjevic modified semi-empirical model Dimitrijevic and Konjevic (1986 Astron. and Astrophy. 163 297 and 1987 Astron. Astrophys. 172 345), which we amend by employing oscillator strengths from Hartree–Fock calculations. This line broadening model applies to near-neutral plasmas with electron temperatures of Te ~ 1 eV and electron densities of Ne ~1017 cm-3. We evaluate the D.K.-inspired model against the previous hydrogenic approach in ATOMIC through comparison to NIST-rated measurements for selected neutral and singly-ionized Ca, O, Fe, and Sn lines using both fine-structure and configuration-averaged oscillator strengths. The new D.K.-inspired model is significantly more accurate than the previous hydrogenic model and we find the use of configuration-averaged oscillator strengths a good approximation for applications such as LIBS (laser induced breakdown spectroscopy), for which we demonstrate the use of the D.K.-inspired model.

  13. Stark broadening of heavy metal spectral lines in atmospheres of chemically peculiar stars

    NASA Astrophysics Data System (ADS)

    Simić, Zoran

    2010-11-01

    Data on the Stark broadening of heavy metal spectral lines are of interest not only for laboratory but also for astrophysical plasma research as e.g. for stellar spectra analysis and synthesis. Here, we investigated theoretically the influence of collisions with charged particles on heavy metal spectral line profiles for Te I, Cr II, Mn II, Au II, Cu III, Zn III, Se III, In III and Sn III in spectra of A stars and white dwarfs. We applied semiclassical theory of Sahal-Bréchot since the most of published results in literature until now are determined using this method. When it can not be applied in an adequate way, due to the lack of reliable atomic data, we used modified semiempirical theory of Dimitrijević & Konjević, Dimitrijević & Kršljanin. Stark broadening parameters, widths and shifts, were obtained for spectral lines of neutral emitter Te I, singly charged emitters Cr II, Mn II and Au II and doubly charged emitters Cu III, Zn III, Se III, In III and Sn III. We considered as well the contributions of different collision processes to the total Stark width in comparison with Doppler one. In this case we obtained contributions for elastic, strong and inelastic collisions for upper and lower levels. For example, chromium lines are interesting due to their presence in stellar atmospheres, so that they give possibility to determine chromium abundance and investigate chromium stratification in stelar atmospheres and to be used for the diagnostics of stellar plasma and for more refined synthesis of stellar spectra. We consider the effect of Stark broadening on the shapes of Cr II spectral lines observed in the spectra of stars in the middle part of the main sequence. Stark broadening parameters were calculated by the semiclassical perturbation approach. For stellar spectra synthesis, the improved version SYNTH3 of the code SYNTH for synthetic spectrum calculations was used. Stark broadening parameters for Cr II spectral lines of seven multiplets belonging to 4s

  14. Observation of Doppler broadening in β -delayed proton-γ decay

    NASA Astrophysics Data System (ADS)

    Schwartz, S. B.; Wrede, C.; Bennett, M. B.; Liddick, S. N.; Pérez-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.

    2015-09-01

    Background: The Doppler broadening of γ -ray peaks due to nuclear recoil from β -delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using β -delayed proton emission or applied to a recoil heavier than A =10 . Purpose: To test and apply this Doppler broadening method using γ -ray peaks from the 26P(β p γ )25Al decay sequence. Methods: A fast beam of 26P was implanted into a planar Ge detector, which was used as a 26P β -decay trigger. The SeGA array of high-purity Ge detectors was used to detect γ rays from the 26P(β p γ )25Al decay sequence. Results: Radiative Doppler broadening in β -delayed proton-γ decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613-keV γ -ray line for which the proton energies were previously known. The 1776-keV γ ray de-exciting the 2720 keV 25Al level was observed in 26P(β p γ )25Al decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is 5.1 ±1.0 (stat.) ±0.6 (syst.) MeV, corresponding to a 26Si excitation energy of 13.3 ±1.0 (stat.) ±0.6 (syst.) MeV for the proton-emitting level. Conclusions: The Doppler broadening method has been demonstrated to provide practical measurements of the energies for β -delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as A =25 .

  15. Action potential broadening and frequency-dependent facilitation of calcium signals in pituitary nerve terminals.

    PubMed

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

    1991-01-15

    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.

  16. Using line broadening to determine the electron density in an argon surface-wave discharge at atmospheric pressure

    SciTech Connect

    Christova, M.; Christov, L.; Castanos-Martinez, E.; Moisan, M.; Dimitrijevic, M. S.

    2008-10-22

    Broadening due to collisions with charged particles (Stark broadening ) and neutral atoms, was determined for Ar I 522.1, 549.6 and 603.2 nm spectral lines from the spectral series 3p{sup 5}nd-3p{sup 5}4p, in order to evaluate the electron density in a surface-wave discharge at atmospheric pressure.

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

    PubMed

    Faber, E S Louise; Sah, Pankaj

    2003-10-15

    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.

  18. Broadening the Study of Participation in the Life Sciences: How Critical Theoretical and Mixed-Methodological Approaches Can Enhance Efforts to Broaden Participation

    PubMed Central

    Metcalf, Heather

    2016-01-01

    This research methods Essay details the usefulness of critical theoretical frameworks and critical mixed-methodological approaches for life sciences education research on broadening participation in the life sciences. First, I draw on multidisciplinary research to discuss critical theory and methodologies. Then, I demonstrate the benefits of these approaches for researchers who study diversity and inclusion issues in the life sciences through examples from two critical mixed-methods studies of prominent issues in science, technology, engineering, and mathematics (STEM) participation and recognition. The first study pairs critical discourse analysis of the STEM workforce literature, data, and underlying surveys with quantitative analyses of STEM pathways into the workforce. This example illustrates the necessity of questioning popular models of retention. It also demonstrates the importance of intersecting demographic categories to reveal patterns of experience both within and between groups whose access to and participation in STEM we aim to improve. The second study’s critical approach applies research on inequities in prizes awarded by STEM professional societies toward organizational change. This example uses data from the life sciences professional societies to show the importance of placing data within context to broaden participation and understand challenges in creating sustainable change. PMID:27521238

  19. Wave Function Parity Loss Used to Mitigate Thermal Broadening in Spin-orbit Coupled Zigzag Graphene Analogues

    NASA Astrophysics Data System (ADS)

    Sadi, Mohammad Abdullah; Liang, Gengchiau

    2017-01-01

    Carrier transport through a graphene zigzag nanoribbon (ZNR) is possible to be blocked by a p-n profile implemented along its transport direction. However, we found that in cases of analogous materials with significant intrinsic spin-orbit coupling (SOC), i.e. silicene and germanene, such a profile on ZNR of these materials allows transmission mostly through spin-orbit coupled energy window due to the loss of the parity of wave functions at different energies caused by SOC. Next, a p-i-n scheme on germanene ZNR is proposed to simultaneously permit edge transmission and decimate bulk transmission. The transmission spectrum is shown to mitigate the effect of thermal broadening on germanene and silicene ZNR based spin-separators by improving spin polarization yield by 400% and 785%, respectively, at 300 K. The importance of proper gate voltage and position for such performance is further elucidated. Finally, the modulation the current output of the proposed U-shape p-i-n device while maintaining its spin polarization is discussed.

  20. Wave Function Parity Loss Used to Mitigate Thermal Broadening in Spin-orbit Coupled Zigzag Graphene Analogues

    PubMed Central

    Sadi, Mohammad Abdullah; Liang, Gengchiau

    2017-01-01

    Carrier transport through a graphene zigzag nanoribbon (ZNR) is possible to be blocked by a p-n profile implemented along its transport direction. However, we found that in cases of analogous materials with significant intrinsic spin-orbit coupling (SOC), i.e. silicene and germanene, such a profile on ZNR of these materials allows transmission mostly through spin-orbit coupled energy window due to the loss of the parity of wave functions at different energies caused by SOC. Next, a p-i-n scheme on germanene ZNR is proposed to simultaneously permit edge transmission and decimate bulk transmission. The transmission spectrum is shown to mitigate the effect of thermal broadening on germanene and silicene ZNR based spin-separators by improving spin polarization yield by 400% and 785%, respectively, at 300 K. The importance of proper gate voltage and position for such performance is further elucidated. Finally, the modulation the current output of the proposed U-shape p-i-n device while maintaining its spin polarization is discussed. PMID:28091616

  1. Direct measurements of collisional Raman line broadening in the S-branch transitions of acetylene (C2H2).

    PubMed

    Hsu, Paul S; Stauffer, Hans U; Jiang, Naibo; Gord, James R; Roy, Sukesh

    2013-10-21

    We report direct measurements of the self- and N2-broadened Raman S-branch linewidths of acetylene (C2H2), obtained by employing time-resolved picosecond rotational coherent anti-Stokes Raman scattering spectroscopy. Using broadband 115-ps pump and Stokes pulses (~135 cm(-1) bandwidth) and a spectrally narrowed 90-ps probe pulse (~0.2 cm(-1) bandwidth), Raman-coherence lifetimes are measured at room temperature for the S-branch (ΔJ = +2) transitions associated with rotational quantum number J = 3-25. These directly measured Raman-coherence lifetimes, when converted to collisional linewidth broadening coefficients, differ from the previously reported broadening coefficients extracted from theoretical calculations by 6%-35% for self-broadening for C2H2 and by up to 60% for N2-broadened C2H2.

  2. Stark Broadening Of Heavy Metal Spectral Lines In Atmospheres Of Chemically Peculiar Stars

    NASA Astrophysics Data System (ADS)

    Simic, Z.

    2010-07-01

    Data on the Stark broadening of heavy metal spectral lines are of interest not only for laboratory but also for astrophysical plasma research as e.g. for stellar spectra analysis and synthesis. Here, we investigated theoretically the influence of collisions with charged particles on heavy metal spectral line profiles for Te I, Cr II, Mn II, Au II, Cu III, Zn III, Se III, In III and Sn III in spectra of A stars and white dwarfs. We applied semiclassical theory of Sahal-Bréchot since the most of published results in literature until now are determined using this method. When it can not be applied in an adequate way, due to the lack of reliable atomic data, we used modified semiempirical theory of Dimitrijevic & Konjevic, Dimitrijevic & Králjanin. Stark broadening parameters, widths and shifts, were obtained for spectral lines of neutral emitter Te I, singly charged emitters Cr II, Mn II and Au II and doubly charged emitters Cu III, Zn III, Se III, In III and Sn III. We considered as well the contributions of different collision processes to the total Stark width in comparison with Doppler one. In this case we obtained distributions for elastic, strong, inelastic collisions from upper and lower levels. For example, chromium lines are interesting due to their presence in stellar atmospheres, so that they give possibility to determine chromium abundance and investigate chromium stratification in stelar atmospheres and to be used for the diagnostics of stellar plasma and for more rafined synthesis of stellar spectra. We consider the effect of Stark broadening on the shapes of Cr II spectral lines observed in the spectra of stars in the middle part of the main sequence. Stark broadening parameters were calculated by the semic- lassical perturbation approach. For stellar spectra synthesis, the improved version SYNTH3 of the code SYNTH for synthetic spectrum calculations was used. Stark broadening parameters for Cr II spectral lines of seven multiplets belonging to 4s-4p

  3. Pressure broadening and line coupling in bending bands of CO2

    NASA Technical Reports Server (NTRS)

    Green, Sheldon

    1989-01-01

    The pressure broadening and line coupling cross sections in the Fano-Ben Reuven theory of line shapes are calculated for bending bands of CO2 in a bath of He atoms. Molecular collision dynamics are simplified by invoking the infinite order sudden (IOS) approximation for molecular rotational and vibrational angular momentum in a manner similar to but not identical with the method developed by Clary and shown to be accurate for CO2-He. Numerical values are obtained using a pairwise additive interaction potential developed by Clary. Predictions are in good accord with data for various infrared bands and pure rotational Raman spectra. It is found that all pressure broadening and state-to-state cross sections depend on only a few dynamical factors (generalized IOS cross sections) and are therefore closely interrelated. Results are used to assess models developed previously to analyze line shapes in this and similar systems.

  4. Broadening of optical transitions in polycrystalline CdS and CdTe thin films

    SciTech Connect

    Li Jian; Chen Jie; Collins, R. W.

    2010-11-01

    The dielectric functions {epsilon} of polycrystalline CdS and CdTe thin films sputter deposited onto Si wafers were measured from 0.75 to 6.5 eV by in situ spectroscopic ellipsometry. Differences in {epsilon} due to processing variations are well understood using an excited carrier scattering model. For each sample, a carrier mean free path {lambda} is defined that is found to be inversely proportional to the broadening of each of the band structure critical points (CPs) deduced from {epsilon}. The rate at which broadening occurs with {lambda}{sup -1} is different for each CP, enabling a carrier group speed {upsilon}{sub g} to be identified for the CP. With the database for {upsilon}{sub g}, {epsilon} can be analyzed to evaluate the quality of materials used in CdS/CdTe photovoltaic heterojunctions.

  5. Calculation of pressure broadening parameters for the CO-He system at low temperatures

    NASA Technical Reports Server (NTRS)

    Green, S.

    1985-01-01

    Theoretical pressure broadening parameters were computed for the 0-1 and 1-2 rotational transitions of CO in He at very low temperatures and compared with the recent experimental measurements at 4.2 K. The interaction potential was taken from extensive SCF-CI calculations, molecular collision dynamics were described by essentially exact converged close coupling calculations, and pressure broadening cross sections were obtained from the collisional S matrices within the accurate Fano-Ben Reuven framework. Resonances at low collision energies give rise to an increase in the thermally averaged cross sections at low temperatures. Although previous calculations for this system at higher temperatures (77-300 K) were in good accord with experiment, at 4.2 K predicted values are about two times larger than experiment; possible sources of this discrepancy are discussed.

  6. Highly bright photon-pair generation in Doppler-broadened ladder-type atomic system.

    PubMed

    Lee, Yoon-Seok; Lee, Sang Min; Kim, Heonoh; Moon, Han Seb

    2016-11-28

    We report a bright photon-pair source with a coincidence counting rate per input power (cps/mW) of tens of thousands, obtained via spontaneous four-wave mixing from a Doppler-broadened atomic ensemble of the 5S1/2-5P3/2-5D5/2 transition of 87Rb. The photon-pair generation rate is enhanced by the two-photon coherence contributions from almost all the atomic velocity groups in the Doppler-broadened ladder-type atomic system. We obtained the violation of the Cauchy-Schwarz inequality by a factor of 2370 ± 150. We believe that our scheme for highly bright paired photons is important as a useful quantum light source for quantum entanglement swapping between completely autonomous sources.

  7. Low Temperature Measurements of HCN Broadened by N2 in the 14-micron Spectral Region

    SciTech Connect

    Smith, M.A.H.; Rinsland, Curtis P.; Blake, Thomas A.; Sams, Robert L.; Benner, D. C.; Devi, V. M.

    2008-04-01

    N2-broadening and N2-pressure-induced shift coefficients; and the temperature dependence exponent of the N2-broadening and the temperature dependent coefficients of N2-pressure-induced shifts have been measured for transitions in the v2 band of HCN from analysis of high-resolution absorption spectra recorded with two different Fourier transform spectrometers. A total of 34 laboratory spectra recorded at 0.002-0.005 cm-1 resolution and at temperatures ranging from 211 to 300 K were used in the determination of various spectral line parameters. A multispectrum nonlinear least squares curve fitting technique employing a modified Voigt line profile including speed dependence was used in the P- and R-branch measurements. In analyzing the Q branch transitions, the off-diagonal relaxation matrix element coefficients were included in analysis to fit the data. Present results are compared to previous measurements reported in the literature.

  8. Photoacoustic measurements of Lorentz broadening in CO2 between 25° C and 450° C

    NASA Astrophysics Data System (ADS)

    Hammerich, M.; Vildrik-Sørensen, L.; de Vries, H.; Henningsen, J.

    1991-09-01

    A variable temperature photoacoustic cell has been constructed and tested by studying the interplay of CO2, H2O, and NH3 in synthetic smoke. Saturation effects for CO2 and NH3 have been modeled and compared with experiments, and results are obtained for the vibrational relaxation rate associated with NH3-H2O collisions. The cell has been used for studying the temperature dependence of self-broadening and N2 broadening of CO2 lines. The temperature dependence of the scattering rate is well described by a T - n law with n=0.77 in both cases. This result agrees with previous results obtained by tunable diode laser spectroscopy, but disagrees with results obtained by indirect methods.

  9. On the mode-coupling theory of vibrational line broadening in near-critical fluids.

    PubMed

    Lawrence, C P; Skinner, J L

    2004-05-08

    Molecular-dynamics simulations of a neat atomic fluid, coupled with a simple model for vibrational frequency perturbations, are used to investigate vibrational line broadening near the liquid-gas critical point. All features of our simulations are in qualitative agreement with recent Raman experiments on nitrogen. We also use our simulation results to assess the validity of the mode-coupling theories that have been used to analyze experiment. We find that the theoretical results are not in good agreement with simulation, both for the temperature dependence of the linewidth, and for the frequency time-correlation functions. However, the mode-coupling prediction that critical line broadening is due to the diverging correlation time of the frequency fluctuations is shown to be correct.

  10. Transverse momentum broadening in semi-inclusive deep inelastic scattering at next-to-leading order

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  11. Parton Energy Loss and Momentum Broadening at NLO in High Temperature QCD Plasmas

    NASA Astrophysics Data System (ADS)

    Ghiglieri, Jacopo; Teaney, Derek

    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 2 ↔ 2 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.

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

    NASA Astrophysics Data System (ADS)

    Ghiglieri, Jacopo; Teaney, Derek

    2015-10-01

    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 ↔ 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.

  13. Investigation on the influence of spectral linewidth broadening on beam quality in spectral beam combination

    NASA Astrophysics Data System (ADS)

    Tian, Fei; Yan, Hong; Chen, Li; Ye, Yidong; Li, Jianmin; Luo, Jia; Lu, Fei

    2015-02-01

    Spectral beam combination (SBC) is a promising method to combine multiple fiber outputs for further power scaling with the capability of maintaining high beam quality, but the beam quality will be degraded with spectral linewidth broadening, because it could result in additional angular spread in the output beam. In this paper, we described theoretical calculation as well as experimental investigation on the influence of spectral linewidth broadening on beam quality. The results show that in single SBC system the spectral linewidth should be limited to less than a few GHz in order to avoid beam quality degradation, but the linewidth requirement could be decreased to more than hundreds of GHz using a pair of parallel gratings, which reveals a feasible way to increase the stimulated Brillouin scattering (SBS)-free power output of single fiber laser for overall output scaling and high beam quality.

  14. Electric field induced broadening of magnetic resonance line in ferrite/piezoelectric bilayer

    NASA Astrophysics Data System (ADS)

    Petrov, V.; Bichurin, M.; Saplev, A.; Tatarenko, A.; Lobekin, V.

    2017-06-01

    The present investigation focuses on magnetoelectric interactions in ferrite-piezoelectric bilayers in the ferromagnetic resonance (FMR) region. A dc electric field applied perpendicular to the sample plane gives rise to an in-plane strain that is transferred to the ferrite and produces a uniaxial thickness-dependent magnetic anisotropy. Expressions for microwave magnetic susceptibility are obtained taking into account the effects of flexural deformations. The results are applied to the specific case of yttrium iron garnet (YIG)/lead zirconate titanate (PZT). The study predicts the unique electric field dependence of FMR line broadening. For the specific YIG to PZT thickness ratio, magnetoelectric coupling results in a weak FMR line shift and considerable line broadening. The results are of interest for novel ferrite-piezoelectric microwave devices.

  15. Stochastic analysis of spectral broadening by a free turbulent shear layer

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  16. Position sensitivity in large spectroscopic LaBr3:Ce crystals for Doppler broadening correction

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  17. Spectral broadening and inhibition of amplitude and frequency modulation in Nd: glass regenerative amplifier

    NASA Astrophysics Data System (ADS)

    Zhang, Yuqi; Pan, Xue; Wang, Jiangfeng; Li, Xuechun

    2014-11-01

    In order to broaden the spectrum of laser pulse and reduce the gain narrowing effect in Nd:glass regenerative amplifier to realize the ambition of inhibiting amplitude and frequency modulation, proper quartz birefringence crystal plate is inserted into the cavity. The influence factors of central wavelength, depth of modulation and range of modulation are obtained theoretically. The width of the spectrum is broadened by controlling all the factors. Two kinds of thickness, 5mm and 6mm, are inserted into the regenerative amplifier cavity. The results of theoretical calculation and experiment both show that the effect of spectrum widening is evident, which reduces the gain narrowing effect to some extent. The amplitude and frequency modulation resulted from gain narrowing effect is inhibited when the central wavelength deflects. The simulated results show that inhibited effect of amplitude and frequency modulation is remarkable. And the method is a potential effective technique for amplitude and frequency modulation inhibition.

  18. Spectral broadening in anatase titanium dioxide waveguides at telecommunication and near-visible wavelengths.

    PubMed

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

    2013-07-29

    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.

  19. A study of the spectral broadening of simulated Doppler signals using FFT and AR modelling.

    PubMed

    Keeton, P I; Schlindwein, F S; Evans, D H

    1997-01-01

    Doppler ultrasound is used clinically to detect stenosis in the carotid artery. The presence of stenosis may be identified by disturbed flow patterns distal to the stenosis that cause spectral broadening in the spectrum of the Doppler signal around peak systole. This paper investigates the behaviour of the spectral broadening index (SBI) derived from wide-band spectra obtained using autoregressive modelling (AR), compared with the SBI based on the fast-Fourier transform (FFT) spectra. Simulated Doppler signals were created using white noise and shaped filters to analyse spectra typically found around the systolic peak and to assess the magnitude and variance of AR and FFT-SBI for a range of signal-to-noise ratios. The results of the analysis show a strong correlation between the indices calculated using the FFT and AR algorithms. Despite the qualitative improvement of the AR spectra over the FFT, the estimation of SBI for short data frames is not significantly improved using AR.

  20. A shock tube study of line broadening in a temperature range of 6100 to 8300 K

    NASA Technical Reports Server (NTRS)

    Baur, J. F.; Cooper, J.

    1977-01-01

    Line widths of the Ca(II) 3968 A and Na(I) 5890 A resonance lines broadened by electric microfields in a plasma were measured. A pressure-driven shock tube was used as the light source. Radiation from the equilibrium region behind the reflected shock wave was studied using a rapid scanning Fabry-Perot interferometer. Electron and argon atom densities of about 8 x 10 to the 16th and 1 x 10 to the 19th/cu cm, respectively, were achieved at the relatively low temperature of around 7500 K by vaporizing a cesium powder that had been added to the shock tube as a solid aerosol in argon gas. The measured line widths were predominantly Stark broadened by the electrons and ions in the plasma, although Doppler, van der Waals, instrument function and optical depth effects had to be taken into account.

  1. Phorbol esters broaden the action potential in CA1 hippocampal pyramidal cells.

    PubMed

    Storm, J F

    1987-03-20

    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.

  2. Excitatory amino acids acting on metabotropic glutamate receptors broaden the action potential in hippocampal neurons.

    PubMed

    Hu, G Y; Storm, J F

    1991-12-24

    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.

  3. Broadening participation in Natural Sciences and Mathematics at the University of Maryland Baltimore County

    NASA Astrophysics Data System (ADS)

    Rous, Philip

    2013-03-01

    Over the past two decades, UMBC has undertaken a series of efforts to broaden participation in the natural sciences and mathematics, beginning with the establishment of the Meyerhoff program. Using as examples the multiple initiatives that followed, and with a focus on the challenge of increasing access and success of all students who enter as both freshmen and transfer students, I will describe a model of culture change that we have employed repeatedly to understand and guide our efforts in broadening participation. Particular attention will be paid to the concept of cultural capital, the role of innovators and the challenge of scaling small-scale innovations towards institutional change. Supported by the National Science Foundation and the Bill and Melinda Gates Foundation.

  4. Hydrogen broadening and collision-induced line shifts of methane at 4200/cm

    NASA Technical Reports Server (NTRS)

    Margolis, Jack S.

    1993-01-01

    Many of the lines of the nu1 + nu4 and nu3 + nu4 bands of methane in the vicinity of 4200/cm have been assigned and are reported in the HITRAN data-base which is commonly used for atmospheric transmission calculations in the IR. The collision-induced broadening coefficients of hydrogen for more than 200 of these lines are reported. Also, by using the water-vapor lines which occur in the spectra as calibration marks, the frequencies of the broadened lines are determined. This permitted the collision-induced line shifts to be measured for lines sufficiently isolated from interfering blends: all of the shifts which could be reliably determined in this way were negative.

  5. An evaluation of algorithms for the deconvolution of Doppler broadening positron annihilation radiation spectroscopy spectra

    NASA Astrophysics Data System (ADS)

    Woo, Teresa K. C.; Cheng, Vincent K. W.; Beling, Christopher D.; Ng, Michael K. P.

    2005-06-01

    Two least squares minimization methods for the deconvolution of 1D Doppler Broadening Annihilation Radiation Spectroscopy (DBARS) spectra have been tested with spectra generated by Monte Carlo simulation according to the following functional forms: inverted triangle, inverted parabola, Laplace, Lorentz and a model DBARS spectrum for a metal composed of an inverted parabola and a Gaussian function. These reference spectra were firstly convoluted with a Gaussian broadening factor and then restored to its original form with the algorithms. The method with Tikhonov regularizer and non-negativity constraint still failed to restore the sharp features of these spectral functions although the negative signal found in an earlier study was removed. On the other hand, the method with the Huber regularizer was successful. Optimization of the deconvolution in terms of regularization parameters is necessary to achieve good deconvolution. The optimization of the deconvolution was checked with visual matching and a quality factor which takes into account the number of counts in the spectrum.

  6. Effect of nuclear motion on spectral broadening of high-order harmonic generation.

    PubMed

    Yuan, Xiaolong; Wei, Pengfei; Liu, Candong; Ge, Xiaochun; Zheng, Yinghui; Zeng, Zhinan; Li, Ruxin

    2016-04-18

    High-order harmonic generation (HHG) in molecular targets is experimentally investigated in order to reveal the role of the nuclear motion played in the harmonic generation process. An obvious broadening in the harmonic spectrum from the H2 molecule is observed in comparison with the harmonic spectrum generated from other molecules with relatively heavy nuclei. We also find that the harmonic yield from the H2 molecule is much weaker than the yield from those gas targets with the similar ionization potentials, such as Ar atom and N2 molecule. The yield suppression and the spectrum broadening of HHG can be attributed to the vibrational motion of nuclear induced by the driving laser pulse. Moreover, the one-dimensional (1D) time-dependent Schrödinger equation (TDSE) with the non-Born-Oppenheimer (NBO) treatment is numerically solved to provide a theoretical support to our explanation.

  7. Experimental and theoretical studies on collision-broadened lines in the nu-4 fundamental of methane.

    NASA Technical Reports Server (NTRS)

    Varanasi, P.; Tejwani, G. D. T.

    1972-01-01

    High-resolution experimental and theoretical studies performed earlier by us on the collision-broadened rotational lines in the nu-3 and 2nu-3 bands of methane have been repeated on the lines in the nu-4 fundamental of the molecule. Line-width measurements and computations, as well as line-shape measurements, indicate that the significant differences which exist between the rotational term values of the nu-3 and nu-4 vibrational levels have no observable effect on the collision-broadening mechanism. Using the predictions of line-widths, based on the Anderson-Tsao-Curnutte theory in the extended version of Tejwani for octopolar molecules, the theoretical dependence of line-widths on temperature has been calculated for CH4-CH4, CH4-H2 and CH4-He collisions.

  8. Direct measurements of collisionally broadened Raman linewidths of CO2 S-branch transitions.

    PubMed

    Roy, Sukesh; Hsu, Paul S; Jiang, Naibo; Gord, Joseph R; Kulatilaka, Waruna D; Stauffer, Hans U; Gord, James R

    2013-01-14

    We report direct measurements of S-branch Raman-coherence lifetimes of CO(2) resulting from CO(2)-CO(2) and CO(2)-N(2) collisions by employing time-resolved picosecond coherent anti-Stokes Raman scattering spectroscopy. The S-branch (ΔJ = +2) transitions of CO(2) with rotational quantum number J = 0-52 were simultaneously excited using a broadband (~5 nm) laser pulse with a full-width-at-half-maximum duration of ~115 ps. The coherence lifetimes of CO(2) for a pressure range of 0.05-1 atm were measured directly by probing the rotational coherence with a nearly transform-limited, 90-ps-long laser pulse. These directly measured Raman-coherence lifetimes, when converted to collisional linewidth broadening coefficients, differ from the previously reported broadening coefficients extracted from frequency-domain rotational Raman and infrared-absorption spectra and from theoretical calculations by 7%-25%.

  9. Broadening of paramagnetic resonance lines by charged point defects in neodymium-doped scheelites

    NASA Astrophysics Data System (ADS)

    Baibekov, E. I.; Zverev, D. G.; Kurkin, I. N.; Rodionov, A. A.; Malkin, B. Z.; Barbara, B.

    2014-05-01

    We study paramagnetic resonance linewidth in a series of CaWO4 and CaMoO4 crystals with different concentrations of neodymium ions (0.0031-0.81 at %). Experimental data are interpreted in the framework of the statistical theory of line broadening by charged point defects. In our calculations, three different contributions are singled out: arising from the local electric fields, electric field gradients and magnetic fields of the nearby point defects. The interaction parameters are determined from the spectroscopic data available for Nd:CaWO4 crystal. Direct calculations of the linewidth are performed for different crystal orientations with respect to external magnetic field. We conclude that major contribution to the broadening comes from the interactions with random electric fields produced by neodymium and charge compensator ions.

  10. N2 pressure - broadened O3 line widths and strengths near 1129.4 cm-1

    NASA Technical Reports Server (NTRS)

    Copeland, G. E.; Majorana, L. N.; Harward, C. N.; Steinkamp, R. J.

    1982-01-01

    A Beer's Law experiment was performed with a tunable diode laser to find the N2 pressure broadening characteristics of a single 03 absorption line at 1129.426 cm for N2 pressures from 10 to 100 torr (O3 pressure = 3.16 torr). SO2 line positions were used for wavelength calibration. Line shapes were interatively fitted to a Lorentz function. Results were delta (HWHM in MHz) = 47.44 (+ or - 5.34) MHz + 1.730 (+ or - 0.088) MHz/torr *p(torr) with sigma = 0.9897. This intercept compares well with the Doppler O3 - O3 broadened (at 3.16 torr) width of 44.52 Hz. This result in a HWHM line width of 0.44 cm atm at 760 torr and 285 K. The line strengths integrated over delta nu = 0.55 cm were found to be N2 pressure dependent.

  11. Nonperturbative finite T broadening of the {rho} meson and dilepton emission in heavy-ion collisions

    SciTech Connect

    Ruppert, Joerg; Renk, Thorsten

    2005-06-01

    We study self-consistently the finite T broadening of the {rho} meson and its implications for dilepton emission in heavy-ion collisions. For this purpose finite width effects at finite temperature due to the {rho}-{pi} interaction are investigated in a self-consistent {phi}-functional approach. The temperature dependence of the {rho} meson and pion spectral functions and self-energies is discussed. The spectral functions show considerable broadening in comparison with a perturbative calculation on the one-loop level. Using these spectral functions, we make a comparison to dilepton emission data from the CERES NA49 Collaboration employing a parametrized fireball evolution model of collision. We demonstrate that these nonperturbative finite width effects are in-medium modifications relevant to the understanding of the enhancement of the low invariant mass spectrum of dileptons emitted in A-A collisions.

  12. Thermal infrared lines of methane broadened by nitrogen at low temperatures

    NASA Technical Reports Server (NTRS)

    Varanasi, P.; Giver, L. P.; Valero, F. P. J.

    1983-01-01

    Measurements of spectral transmittance in the nu4-fundamental band of (C-12)H4 have been performed at low temperatures using a Fourier transform spectrometer with apodized spectral resolution of 0.06 per cm. With applications to lines formed in the atmospheres of Titan and earth in mind, N2 has been used as the broadening gas. Comparisons of observed and computed spectral transmittances on a line-by-line basis have yielded line strengths, N2-broadened half-widths and their variation with temperature. Best agreement between measured and computed spectra was obtained when the absolute intensity of the band was taken as 128 per (sq cm-atm) at 296 K. Line widths were found to vary as T to the n power with n = -1.0 for lines of the F-species and 0.63 for the A-species. The measured line widths are considerably larger than those used in the AFGL compilation.

  13. Theoretical calculations of pressure broadening coefficients for H2O perturbed by hydrogen or helium gas

    NASA Technical Reports Server (NTRS)

    Gamache, Robert R.; Pollack, James B.

    1995-01-01

    Halfwidths were calculated for H2O with H2 as a broadening gas and were estimated for He as the broadening species. The calculations used the model of Robert and Bonamy with parabolic trajectories and all relevant terms in the interaction potential. The calculations investigated the dependence of the halfwidth on the order of the atom-atom expansion, the rotational states, and the temperature in the range 200 to 400K. Finally, calculations were performed for many transitions of interest in the 5 micrometer window region of the spectrum. The resulting data will be supplied to Dr. R. Freedman for extracting accurate water mixing ratios from the analysis of the thermal channels for the Net Flux experiment on the Galileo probe.

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

    SciTech Connect

    Berdnikov, Yury; Schmidtbauer, Jan; Borg, Mattias; Johansson, Jonas; Dubrovskii, Vladimir

    2016-06-17

    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.

  15. Doppler broadening effect on collision cross section functions - Deconvolution of the thermal averaging

    NASA Technical Reports Server (NTRS)

    Bernstein, R. B.

    1973-01-01

    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.

  16. Stark broadening of Zr IV spectral lines in the atmospheres of chemically peculiar stars

    NASA Astrophysics Data System (ADS)

    Majlinger, Zlatko; Simić, Zoran; Dimitrijević, Milan S.

    2017-09-01

    Stark widths for 18 Zr IV spectral lines have been calculated by using the modified semi-empirical method. The obtained results have been used to investigate the influence of Stark broadening on the spectra of atmospheres of chemically peculiar stars of A spectral type and hydrogen-rich DA and helium-rich DB white dwarfs. Our results have been used also to test possibility to predict new data using some approximate methods developed on the basis on regularities and systematic trends.

  17. A mode-coupling theory of vibrational line broadening in near-critical fluids.

    PubMed

    Egorov, S A; Lawrence, C P; Skinner, J L

    2005-04-14

    We present a fully microscopic mode-coupling theory of near-critical line broadening. All the structural and dynamical input required by the theory is calculated directly from intermolecular potentials. We compute vibrational frequency time-correlation functions and line shapes as the critical point is approached along both the critical isochore and the liquid-gas coexistence curve. Theory is shown to be in good agreement with simulation.

  18. Broadening and shift of Fe I lines perturbed by atomic hydrogen

    SciTech Connect

    Gomez, M.T.; Marmolino, C.; Roberti, R.; Severino, G.

    1987-01-01

    The broadening and shift parameters for a number of Fe I lines perturbed by atomic hydrogen are computed using the interatomic potential due to Hindmarsh et al (1967, 1970). It is also shown that the rms radius and the effective radius of the radiating atom, which determine the force constants in the interatomic potential, can be simply related to each other depending on the orbital quantum number of the atomic level.

  19. Multiple relaxation and inhomogeneous broadening in resonance enhanced Raman scattering - Application to tunable infrared generation

    NASA Technical Reports Server (NTRS)

    Ryan, J. C.; Lawandy, N. M.

    1989-01-01

    The solutions for the imaginary susceptibility of the Raman field transition with arbitrary relaxation rates and field strengths are examined for differing sets of relaxation rates with emphasis on alkali metal vapors which have spontaneous emission dominated relaxation. The model is further expanded to include Doppler broadening and used to predict the peak gain as a function of detuning for a frequency doubled alexandrite laser-pumped cesium vapor gain cell.

  20. Broadening Army Leaders for the Volatile, Uncertain, Complex and Ambiguous Environment

    DTIC Science & Technology

    2012-02-01

    Petraeus. It is defined in the Army’s Commissioned Officer Professional and Career Development Pamphlet 600- 3 (DA PAM 600-3) as: Developmental ...required skills and assignments for continued development and promotion (see Figure 1): Figure 1: Infantry Officer Developmental Model58 However, in...tempo decreases, it has a unique opportunity to 1) develop and implement an officer broadening program through the establishment of a balanced career

  1. Multiple relaxation and inhomogeneous broadening in resonance enhanced Raman scattering - Application to tunable infrared generation

    NASA Technical Reports Server (NTRS)

    Ryan, J. C.; Lawandy, N. M.

    1989-01-01

    The solutions for the imaginary susceptibility of the Raman field transition with arbitrary relaxation rates and field strengths are examined for differing sets of relaxation rates with emphasis on alkali metal vapors which have spontaneous emission dominated relaxation. The model is further expanded to include Doppler broadening and used to predict the peak gain as a function of detuning for a frequency doubled alexandrite laser-pumped cesium vapor gain cell.

  2. Doppler broadening effect on collision cross section functions - Deconvolution of the thermal averaging

    NASA Technical Reports Server (NTRS)

    Bernstein, R. B.

    1973-01-01

    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.

  3. Improving resolution in proton solid-state NMR by removing nitrogen-14 residual dipolar broadening

    NASA Astrophysics Data System (ADS)

    Stein, Robin S.; Elena, Bénédicte; Emsley, Lyndon

    2008-06-01

    Residual dipolar coupling between quadrupolar and other nuclei under MAS has not usually been thought to be important in high field NMR spectroscopy. We show that coupling to 14N broadens 1H lineshapes significantly even at 11.7 T, and that we can decouple 14N from 1H during 1H homonuclear decoupling to successfully improve 1H resolution. The method used for decoupling is the application of evenly spaced pulses to the quadrupolar nucleus.

  4. Line mixing in H broadening of the Na 3P-3D lines

    NASA Astrophysics Data System (ADS)

    Sanchez-Fortún Stoker, J.; Dickinson, A. S.

    2003-04-01

    Line mixing of the Na 3P-3D lines broadened by atomic hydrogen has been calculated in the impact approximation. The required S-matrix elements are calculated using a time-dependent close-coupling rectilinear-path approximation, the ab initio NaH potentials used by Leininger et al (2000 J. Phys. B: At. Mol. Opt. Phys. 33 1805) being employed. At energies of less than 25 000 cm-1, the real and imaginary parts of the mixing cross sections were found to be about 50 and about 25 times smaller, respectively, than the broadening coefficients, while at about 105 cm-1, the real and imaginary parts were found to be smaller in magnitude by factors of about 200 and 10, respectively. On thermally averaging the cross sections, the line-shape parameters leading to mixing were found to be 50-100 times smaller than the corresponding broadening coefficients for the isolated lines. For a number density of 1016 - 1017 cm-3 and temperature of 6000 K, the mixed and unmixed line shapes were found to deviate by less than 3% over the range of frequencies for which the application of the impact approximation was valid.

  5. Hydrogen Balmer-α line broadening in a microwave plasma source

    NASA Astrophysics Data System (ADS)

    Tatarova, E.; Dias, F. M.; Puac, N.; Ferreira, C. M.

    2007-02-01

    Emission spectroscopy was used to investigate the Balmer-α line broadening in a slot-antenna excited microwave plasma source operating in helium hydrogen and argon hydrogen mixtures, and in pure hydrogen at low pressure (p = 0.3 mbar). No evidence was found for excessive broadening of the Hα line under the present operating conditions, even though this line was found to be broader than the helium singlet line at 667.8 nm. The Doppler temperatures corresponding to this helium line (~650 K) are close to the rotational temperatures (~500 K) determined from the Q-branch of the Fulcher-α band under the same conditions. The Doppler temperatures corresponding to the Balmer-α broadening are about 3000 K. The Hα line shape does not change as the amount of hydrogen (up to 50%) in the He H2 mixture is changed. The results indicate selective heating of H atoms in low-pressure He H2, Ar H2 and H2 microwave plasmas.

  6. The 0 --> 3 Overtone Band of CO: Precise Linestrengths and Broadening Parameters.

    PubMed

    Henningsen; Simonsen; Møgelberg; Trudsø

    1999-02-01

    Linestrengths and self-broadening parameters are determined with a standard uncertainty of 1% for 21 lines in the R branch of the 0 --> 3 overtone band of CO around 1.57 µm. The values are lower than those given in the Hitran database by 6-8% for the linestrengths and 1-5% for the collision broadening parameters, and they agree within 0-2% with more recent results obtained with FTIR. Also, results are given for foreign gas broadening by N2 and H2O. The line profiles show clear evidence for collisional narrowing with deviations corresponding to those expected for a Galatry profile. When analyzed in terms of a Voigt profile, this effect causes a reduction in effective Doppler width of about 5%. The linestrengths determined for gas mixtures are used for producing independent values for the CO concentrations. These results are derived without reference to any certified gas standard, and it is suggested that optical spectroscopy satisfies the criteria of a primary method set up by the Consultative Committee for Quantity of Matter (CCQM). Copyright 1999 Academic Press.

  7. Thickness uniformity of beryllium foils derived from energy loss broadening of transmitted MeV protons

    NASA Astrophysics Data System (ADS)

    Hietel, B.; Wittmaack, K.

    2000-03-01

    The thickness uniformity of beryllium foils commonly in use as entrance windows of Si(Li) detectors has been determined by measuring the broadening in energy loss of 1.5-2.5 MeV protons transmitted through such foils. The energy loss spectra were measured after backscattering of the transmitted protons from a thin layer of gold on a polypropylene film. The contribution due to energy loss straggling was assessed in transmission studies on uniform films of polypropylene and polyester (Mylar). The full width at half maximum (FWHM) of the loss peaks for the polymer films increased with the square root of the energy loss Δ E, in accordance with theory. By contrast, the FWHM of the energy loss in Be increased linearly with increasing Δ E, with a maximum FWHM=0.21Δ E at 2.5 MeV. After correcting for the straggling contribution in quadrature, the net excess broadening was found to range from 18% to 20%, for Be foils with a nominal thickness between 12.5 and 37.5 μm. The excess broadening is attributed to a corresponding variation in thickness across the foils, probably due to a significant porosity generated during the fabrication process (sintering). This result supports previous indirect evidence derived from studies on background generation in proton-induced X-ray emission spectrometry (PIXE).

  8. Linear and nonlinear light propagations in a Doppler-broadened medium via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Li, Liang; Huang, Guoxiang

    2010-08-01

    We present a systematic theoretical study to deal with linear and nonlinear light propagations in a Doppler-broadened three-level Λ system via electromagnetically induced transparency (EIT), with incoherent population exchange between two lower energy levels taken into account. Through a careful analysis of base state and linear excitation, we show that the EIT condition of the system is given by |Ωc|2γ31≫2γ21ΔωD2, where Ωc is half the Rabi frequency of the control field, ΔωD is the Doppler width, and γjl is the decay rate of the coherence between states |j> and |l>. Under this condition, the effect of incoherent population exchange is insignificant, while dephasing dominates the decoherence of the system. This condition also ensures the validity of the weak nonlinear perturbation theory used in this work for solving the Maxwell-Bloch equations with inhomogeneous broadening. We then investigate the nonlinear propagation of the probe field and show that it is possible to form temporal optical solitons in the Doppler-broadened medium. Such solitons have ultraslow propagating velocity and can be generated in very low light power. The possibility of realizing (1+1)-dimensional and (2+1)-dimensional spatial optical solitons in the adiabatic regime of the system is also discussed.

  9. Linear and nonlinear light propagations in a Doppler-broadened medium via electromagnetically induced transparency

    SciTech Connect

    Li Liang; Huang Guoxiang

    2010-08-15

    We present a systematic theoretical study to deal with linear and nonlinear light propagations in a Doppler-broadened three-level {Lambda} system via electromagnetically induced transparency (EIT), with incoherent population exchange between two lower energy levels taken into account. Through a careful analysis of base state and linear excitation, we show that the EIT condition of the system is given by |{Omega}{sub c}|{sup 2{gamma}}{sub 31}>>2{gamma}{sub 21{Delta}{omega}D}{sup 2}, where {Omega}{sub c} is half the Rabi frequency of the control field, {Delta}{omega}{sub D} is the Doppler width, and {gamma}{sub jl} is the decay rate of the coherence between states |j> and |l>. Under this condition, the effect of incoherent population exchange is insignificant, while dephasing dominates the decoherence of the system. This condition also ensures the validity of the weak nonlinear perturbation theory used in this work for solving the Maxwell-Bloch equations with inhomogeneous broadening. We then investigate the nonlinear propagation of the probe field and show that it is possible to form temporal optical solitons in the Doppler-broadened medium. Such solitons have ultraslow propagating velocity and can be generated in very low light power. The possibility of realizing (1+1)-dimensional and (2+1)-dimensional spatial optical solitons in the adiabatic regime of the system is also discussed.

  10. Pressure-broadening of water transitions near 7180 cm-1 by helium isotopes

    NASA Astrophysics Data System (ADS)

    Campbell, H. M.; Havey, D. K.

    2013-05-01

    In this study, pressure-broadening parameters for several H2O transitions near 7180 cm-1 are obtained which describe collisions with 3He and 4He. 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 3He and 4He, 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%.

  11. Labeling strategy and signal broadening mechanism of Protein NMR spectroscopy in Xenopus laevis oocytes.

    PubMed

    Ye, Yansheng; Liu, Xiaoli; Chen, Yanhua; Xu, Guohua; Wu, Qiong; Zhang, Zeting; Yao, Chendie; Liu, Maili; Li, Conggang

    2015-06-08

    We used Xenopus laevis oocytes, a paradigm for a variety of biological studies, as a eukaryotic model system for in-cell protein NMR spectroscopy. The small globular protein GB1 was one of the first studied in Xenopus oocytes, but there have been few reports since then of high-resolution spectra in oocytes. The scarcity of data is at least partly due to the lack of good labeling strategies and the paucity of information on resonance broadening mechanisms. Here, we systematically evaluate isotope enrichment and labeling methods in oocytes injected with five different proteins with molecular masses of 6 to 54 kDa. (19) F labeling is more promising than (15) N, (13) C, and (2) H enrichment. We also used (19) F NMR spectroscopy to quantify the contribution of viscosity, weak interactions, and sample inhomogeneity to resonance broadening in cells. We found that the viscosity in oocytes is only about 1.2 times that of water, and that inhomogeneous broadening is a major factor in determining line width in these cells.

  12. Stark broadening measurements in plasmas produced by laser ablation of hydrogen containing compounds

    NASA Astrophysics Data System (ADS)

    Burger, Miloš; Hermann, Jörg

    2016-08-01

    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.

  13. Nitrogen-Broadened 13CH_4 at 80 TO 296 K

    NASA Astrophysics Data System (ADS)

    Smith, M. A. H.; Sung, K.; Brown, L. R.; Crawford, T. J.; Mantz, A. W.; Devi, V. Malathy; Benner, D. Chris

    2011-06-01

    High-resolution spectra of the ν_4 fundamental band of 13CH_4 broadened by N_2 at temperatures relevant to the atmosphere of Titan were recorded using temperature-controlled absorption cells installed in the sample compartment of a Bruker IFS-125HR Fourier Transform spectrometer (FTS) at the Jet Propulsion Laboratory (JPL). Analysis of these spectra using multispectrum fitting has determined half widths, pressure-induced shifts, line mixing parameters and their temperature dependences for transitions belonging to a number of P- and R-branch J-manifolds. The analysis examined in detail the temperature-dependence of N_2-broadened half width and pressure-induced shift coefficients over the entire temperature range from 80 K to 296 K. The results are compared with other published measurements of N_2- and air-broadened methane parameters. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration. K. Sung, A. W. Mantz, M. A. H. Smith, L. R. Brown, T. J. Crawford, V. Malathy Devi and D. C. Benner, JMS 262 (2010) 122-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. A. Atkins, JQSRT 53 (1995) 705-721.

  14. Broadening of the thermal component of the prompt GRB emission due to rapid temperature evolution

    NASA Astrophysics Data System (ADS)

    Bharali, Priya; Sahayanathan, Sunder; Misra, Ranjeev; Boruah, Kalyanee

    2017-08-01

    The observations of the prompt emission of gamma ray bursts (GRB) by GLAST Burst Monitor (GBM), on board Fermi Gamma-ray Space Telescope, suggest the presence of a significant thermal spectral component, whose origin is not well understood. Recently, it has been shown that for long duration GRBs, the spectral width as defined as the logarithm of the ratio of the energies at which the spectrum falls to half its peak value, lie in the range of 0.84-1.3 with a median value of 1.07. Thus, while most of the GRB spectra are found to be too narrow to be explained by synchrotron emission from an electron distribution, they are also significantly broader than a blackbody spectrum whose width should be 0.54. Here, we consider the possibility that an intrinsic thermal spectrum from a fire-ball like model, may be observed to be broadened if the system undergoes a rapid temperature evolution. We construct a toy-model to show that for bursts with durations in the range 5-70 s, the widths of their 1 second time-averaged spectra can be at the most ≲ 0.557. Thus, while rapid temperature variation can broaden the detected spectral shape, the observed median value of ˜ 1.07 requires that there must be significant sub-photospheric emission and/or an anisotropic explosion to explain the broadening for most GRB spectra.

  15. Experimental and theoretical studies of pressure broadened alkali-metal lines for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Shindo, F.; Zhu, C.; Babb, J.; Yoshino, K.; Dalgarno, A.; Kirby, K.

    2006-05-01

    We are undertaking a program of experimental and theoretical studies of the pressure broadening of Na and K by He and H2. This work is motivated by the need for accurate absorption coefficients to validate models of atmospheric opacities which can be used to characterize properties such as gravity and effective temperature of brown dwarfs or predict spectra of irradiated extrasolar giant planets. Due to the collisions with gaseous H2 and He at high concentration in these objects with temperatures of around 1000 K, the profiles of Na and K lines (respectively at 590 nm and 770 nm) are strongly broadened by at least 100 nm. The design of our spectroscopic experiment allows us to collect absorption spectra of alkali vapors at temperatures around 900 K in the presence of buffer gas at pressures of several hundred torr. The atomic densities are measured precisely using the anomalous dispersion (``hook'') method. Investigating the spectral range 380-920 nm, we observed the broadening of the K 770 nm lines and we find the K 404 nm doublet exhibits a putative satellite feature on its blue wing. The theoretical calculations utilize accurate molecular potential energies and transition dipole moments and fully quantum-mechanical methods. Supported in part by NASA grant NAG5-12751

  16. Laboratory spectroscopy of nitrogen-broadened methane at 79 K to 297 K

    NASA Astrophysics Data System (ADS)

    Smith, M. A. H.; Mantz, A. W.; Sung, K.; Brown, L. R.; Crawford, T. J.; Malathy Devi, V.; Benner, D. Chris

    2010-04-01

    To support the remote sensing of Titan's atmosphere, we studied the temperature dependence of the nitrogen-broadened spectrum of the three most abundant methane isotopomers (12CH4, 13CH4, and CH3D) in the 7.5-micron region. For this purpose a temperature stabilized cryogenic cell, cooled by a closed-cycle helium refrigerator, was designed to be fit into the sample compartment of a Bruker high-resolution Fourier transform spectrometer. Two generations of this cell, built at Connecticut College, have been used to record N2-broadened methane spectra with the Bruker IFS-125HR spectrometer at the Jet Propulsion Laboratory (JPL). Nitrogen-broadened spectra of all three methane isotopomers were recorded at temperatures between 79.3 K and 297.1 K. The spectra are analyzed using a multispectrum fitting technique to determine the temperature-dependences of line widths, pressure-induced shifts, and line mixing parameters. Preliminary results will be shown and compared with the few available literature values. The research described in this paper was performed at NASA Langley, the Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and the College of William and Mary under contracts and grants with the National Aeronautics and Space Administration.

  17. Infrared Spectra of N_2-BROADENED 13CH_4 at Titan Atmospheric Temperatures

    NASA Astrophysics Data System (ADS)

    Smith, M. A. H.; Sung, K.; Brown, L. R.; Crawford, T. J.; Mantz, A. W.; Devi, V. Malathy; Benner, D. Chris

    2010-06-01

    High-resolution spectra of the ν_4 fundamental band of 13CH_4 broadened by N_2 at temperatures relevant to the atmosphere of Titan (80 K to 296 K) have been recorded using new temperature-controlled absorption cells installed in the sample compartment of a Bruker (IFS-125HR) Fourier Transform spectrometer (FTS) at the Jet Propulsion Laboratory (JPL). Details of the cells and spectrometer performance have been discussed in the previous talk. Early analysis of these spectra using multispectrum fitting has determined half widths, pressure-induced shifts, line mixing parameters and their temperature dependences for R-branch transitions from R(0) through R(6). In addition to the initial R(2) study mentioned in the previous talk, the analysis for the other J-manifolds examined in detail whether or not the N_2-broadened half width coefficients follow the simple power-law temperature-dependence over the entire temperature range from 80 K to 296 K. The results are compared with other published measurements of N_2-broadened methane parameters at low temperatures. A. W. Mantz et al., Closed-cycle He-cooled absorption cells designed for a Bruker IFS-125HR: First results between 79 K and 297 K, this session. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  18. Proton lateral broadening distribution comparisons between GRNTRN, MCNPX, and laboratory beam measurements

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  19. Analysis of pressure-broadened ozone spectra in the 3 micron region

    NASA Technical Reports Server (NTRS)

    Prochaska, Eleanor S.

    1991-01-01

    This work involves the analysis of a series of McMath Fourier Transform Infrared (FTIR) spectra of ozone broadened by mixing with air (four different pressures), nitrogen (three pressures), or oxygen (three pressures). Each spectrum covers the region from 2396 to 4057 cm(-1). This study focused on the 3 sub nu sub 3 band in t 3000 to 3060 cm(-1). The band is analyzed by first dividing its region into small intervals containing a few well isolated absorption lines of reasonable intensity. Each of these small intervals is fit by multiple iterations of the nonlinear least squares program until residuals (the difference between calculated and observed spectrum, as a percent of the strongest intensity in the interval) are minimized to a reasonable value which corresponds to the noise level of the measured spectrum. Position, intensity, and half-width are recorded for later analysis. From the measured half-widths, a pressure broadening coefficient was determined for each absorption line. Pressure shifts were determined by comparing observed line positions in the spectra of the diluted ozone samples to tabulated line positions determined from spectra of pure gas samples. Comparisons to other work on ozone indicate that the broadening and shift coefficients determined in this study are consistent with those determined in other spectral regions.

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

    PubMed

    Campbell, H M; Havey, D K

    2013-05-15

    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%. Copyright © 2013. Published by Elsevier B.V.

  1. Proton Lateral Broadening Distribution Comparisons Between GRNTRN, MCNPX, and Laboratory Beam Measurements

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  2. Spectral broadening of parametric instability in lower hybrid current drive at a high density

    NASA Astrophysics Data System (ADS)

    Cesario, R.; Amicucci, L.; Cardinali, A.; Castaldo, C.; Marinucci, M.; Napoli, F.; Paoletti, F.; De Arcangelis, D.; Ferrari, M.; Galli, A.; Gallo, G.; Pullara, E.; Schettini, G.; Tuccillo, A. A.

    2014-04-01

    The important goal of adding to the bootstrap current a more flexible tool, capable of producing and controlling steady-state profiles with a high fraction of non-inductive plasma current, could be reached using the lower hybrid current drive (LHCD) effect. Experiments performed on FTU (Frascati Tokamak Upgrade) demonstrated that LHCD can occur at reactor-graded high plasma density, provided that the parametric instability (PI)-produced broadening of the spectrum launched by the antenna is reduced under proper operating conditions, capable of producing relatively high temperature in the outer region of plasma column. This condition was produced by operations that reduce particle recycling from the vessel walls, and enhance the gas fuelling in the core by means of fast pellet. New results of FTU experiments are presented documenting that the useful effect of temperature at the periphery, which reduces the LH spectral broadening and enhances the LH-induced hard-x ray emission level, occurs in a broader range of plasma parameters than in previous work. Modelling results show that a further tool for helping LHCD at a high density would be provided by electron cyclotron resonant heating of plasma periphery. New information is provided on the modelling, able determining frequencies, growth rates and LH spectral broadening produced by PI, which allowed assessing the new method for enabling LHCD at high densities. Further robustness is provided to theoretical and experimental fundaments of the method for LHCD at a high density.

  3. Pathways to Ocean Sciences: Broadening Participation in Ocean Sciences REU Programs

    NASA Astrophysics Data System (ADS)

    Fauver, A.; Johnson, A.; Detrick, L.; Cash, C.; Siegfried, D.; Valaitis, S.; Saywell, D.; Thomas, S. H.

    2011-12-01

    Increasing the number and diversity of students who successfully pursue careers in Ocean Sciences is key to addressing the growing demand for professionals in our fields who genuinely understand and make a contribution to cutting edge research. Summer research programs for undergraduates play a critical role in this process by creating environments in which students can develop the strategies and professional skills necessary to pursue meaningful careers in various STEM fields and by supporting students as they "bridge" between undergraduate and graduate studies. Within the framework of a diversity briefing illuminating the context behind efforts to broaden participation, the Institute for Broadening Participation (IBP) will provide a short overview on the current state of diversity in the Ocean Sciences community in general and the NSF Ocean Sciences REU community in particular, as well as offer a shared resource pool of studies, references, practical tools and strategies focusing on broadening the participation of women and underrepresented groups in higher education. IBP has been supporting diversity by fostering an on-going exchange of ideas and resources between students, faculty and administrators since 2002. Their web portal, www.pathwaystoscience.org, provides easy access to many resources that support students in successful careers in the STEM fields and support faculty and administrators in enhancing their efforts to increase diversity.

  4. Spectroscopic study of unique line broadening and inversion in low-pressure microwave generated water plasmas

    NASA Astrophysics Data System (ADS)

    Mills, R. L.; Ray, P. C.; Mayo, R. M.; Nansteel, M.; Dhandapani, B.; Phillips, J.

    2005-12-01

    It was demonstrated that low pressure (˜0.2 torr) water vapor plasmas generated in a 10 mm inner diameter quartz tube with an Evenson microwave cavity show at least two features that are not explained by conventional plasma models. First, significant (gt2.5Å) hydrogen Balmer alpha line broadening, of constant width, up to 5 cm from the microwave coupler was recorded. Only hydrogen, and not oxygen, showed significant line broadening. This feature, observed previously in hydrogen-containing mixed gas plasmas generated with high voltage dc and rf discharges, was explained by some researchers as resulting from acceleration of hydrogen ions near the cathode. This explanation cannot apply to the line broadening observed in the (electrodeless) microwave plasmas generated in this work, particularly at distances as great as 5 cm from the microwave coupler. Second, inversion of the line intensities of both the Lyman and Balmer series, again at distances up to 5 cm from the coupler, were observed. The line inversion suggests the existence of a hitherto unknown source of pumping of the optical power in plasmas. Finally, it is notable that other aspects of the plasma including the OH* rotational temperature and low electron concentrations are quite typical of plasmas of this type.

  5. Broadening the Study of Participation in the Life Sciences: How Critical Theoretical and Mixed-Methodological Approaches Can Enhance Efforts to Broaden Participation.

    PubMed

    Metcalf, Heather

    This research methods Essay details the usefulness of critical theoretical frameworks and critical mixed-methodological approaches for life sciences education research on broadening participation in the life sciences. First, I draw on multidisciplinary research to discuss critical theory and methodologies. Then, I demonstrate the benefits of these approaches for researchers who study diversity and inclusion issues in the life sciences through examples from two critical mixed-methods studies of prominent issues in science, technology, engineering, and mathematics (STEM) participation and recognition. The first study pairs critical discourse analysis of the STEM workforce literature, data, and underlying surveys with quantitative analyses of STEM pathways into the workforce. This example illustrates the necessity of questioning popular models of retention. It also demonstrates the importance of intersecting demographic categories to reveal patterns of experience both within and between groups whose access to and participation in STEM we aim to improve. The second study's critical approach applies research on inequities in prizes awarded by STEM professional societies toward organizational change. This example uses data from the life sciences professional societies to show the importance of placing data within context to broaden participation and understand challenges in creating sustainable change. © 2016 H. Metcalf. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  6. Spectral broadening and compression of high-intensity laser pulses in quasi-periodic systems with Kerr nonlinearity

    SciTech Connect

    Vlasov, Sergei N; Koposova, E V; Yashin, V E

    2012-11-30

    We report the results of theoretical studies and numerical simulations of optical high-power pulse compression systems based on the spectral broadening in a Kerr nonlinear medium with subsequent pulse compression in a dispersive delay line. It is shown that the effective spectral broadening requires suppressing a smallscale instability arising due to self-focusing, which is possible in quasi-periodic systems consisting of a nonlinear medium and optical relay telescopes transmitting images of the laser beam through the system. The numerical calculations have shown the possibility of broadening the spectrum, followed by 15-fold pulse compression until the instability is excited. (control of laser radiation parameters)

  7. Spectral Broadening of Excitation induced by Ultralong-range Interaction in a Cold Gas of Rydberg Atoms

    SciTech Connect

    Loboda, A. V.; Mischenko, E. V.; Gurnitskaya, E. P.; Glushkov, A. V.; Khetselius, O. Yu.

    2008-10-22

    Preliminary results of calculating the broadening of spectral lines of excited atoms induced by ultralong- range (100 Bohr radii) interactions in a cold gas of Rb atoms within the 'own pressure' approximation and perturbation theory formalism are presented.

  8. The IACOB project. IV. New predictions for high-degree non-radial mode instability domains in massive stars and their connection with macroturbulent broadening

    NASA Astrophysics Data System (ADS)

    Godart, M.; Simón-Díaz, S.; Herrero, A.; Dupret, M. A.; Grötsch-Noels, A.; Salmon, S. J. A. J.; Ventura, P.

    2017-01-01

    Context. Asteroseismology is a powerful tool to access the internal structure of stars. Apart from the important impact of theoretical developments, progress in this field has been commonly associated with the analysis of time-resolved observations. Recently, the so-called macroturbulent broadening has been proposed as a complementary and less expensive way - in terms of observational time - to investigate pulsations in massive stars. Aims: We assess to what extent this ubiquitous non-rotational broadening component which shapes the line profiles of O stars and B supergiants is a spectroscopic signature of pulsation modes driven by a heat mechanism. Methods: We compute stellar main-sequence and post-main-sequence models from 3 to 70 M⊙ with the ATON stellar evolution code, and determine the instability domains for heat-driven modes for degrees ℓ = 1-20 using the adiabatic and non-adiabatic codes LOSC and MAD. We use the observational material compiled in the framework of the IACOB project to investigate possible correlations between the single snapshot line-broadening properties of a sample of ≈260 O and B-type stars and their location inside or outside the various predicted instability domains. Results: We present an homogeneous prediction for the non-radial instability domains of massive stars for degree ℓ up to 20. We provide a global picture of what to expect from an observational point of view in terms of the frequency range of excited modes, and we investigate the behavior of the instabilities with respect to stellar evolution and the degree of the mode. Furthermore, our pulsational stability analysis, once compared to the empirical results, indicates that stellar oscillations originated by a heat mechanism cannot explain alone the occurrence of the large non-rotational line-broadening component commonly detected in the O star and B supergiant domain. Based on observations made with the Nordic Optical Telescope, operated by NOTSA, and the Mercator

  9. Broadening engineering education: bringing the community in : commentary on "social responsibility in French engineering education: a historical and sociological analysis".

    PubMed

    Conlon, Eddie

    2013-12-01

    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.

  10. Measurements of Methane at 7.5 μm Broadened by Nitrogen at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Smith, Mary-Ann H.; Mantz, A. W.; Sung, K.; Brown, L. R.; Crawford, T. J.; Malathy Devi, V.; Benner, D. Chris

    2010-10-01

    Since the ν4 band system of methane (CH4) at 7.5 µm appears prominently in infrared spectra of Titan's atmosphere, we are conducting laboratory studies to examine the temperature-dependence of infrared transitions of CH4 broadened by N2 in this spectral region. Spectra of methane-nitrogen mixtures at temperatures from 79 to 297 K were obtained at 0.006 cm-1 resolution (resolving power = 2x105) using the Bruker IFS 125HR Fourier transform spectrometer at the Jet Propulsion Laboratory with new temperature-controlled gas cells designed specifically to fit in the spectrometer's sample compartment. Details of the cells and spectrometer performance [1] are described in an adjacent poster by Sung et al. A multispectrum nonlinear least squares technique [2] is used to fit selected intervals of 9 or more spectra simultaneously to obtain the temperature dependences of line broadening, pressure-induced shift and line mixing parameters. Results for 13CH4 at 80 to 297 K are discussed relative to our previous high-resolution studies of air- and self-broadened 12CH4 and 13CH4 [3-5] at terrestrial atmospheric temperatures (210 to 314 K). This research is supported by NASA's Planetary Atmospheres Program. 1. K. Sung et al., J. Mol. Spectrosc. (2010) doi:10.1016/j.jms.2010.05.004. 2. D. Chris Benner et al., J. Quant. Spectrosc. Radiat. Transfer 53 (1995) 705-721. 3. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer 110 (2009) 639-653. 4. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer 111 (2010) 1152-1166. 5. M. A. H. Smith et al., J. Quant. Spectrosc. Radiat. Transfer (2010) submitted.

  11. On the Origin of the Scatter Broadening of Fast Radio Burst Pulses and Astrophysical Implications

    NASA Astrophysics Data System (ADS)

    Xu, Siyao; Zhang, Bing

    2016-12-01

    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.

  12. Broadening and shifting of Bragg reflections of nanoscale-microtwinned LT-Ni3Sn2

    NASA Astrophysics Data System (ADS)

    Leineweber, Andreas; Krumeich, Frank

    2013-12-01

    The effect of nanoscale microtwinning of long-range ordered domains in LT-Ni3Sn2 on its diffraction behaviour was studied by X-ray powder diffraction and electron microscopy. LT-Ni3Sn2 exhibits a Ni2In/NiAs-type structure with a superstructure breaking the symmetry relative to the hexagonal high-temperature (HT) to the orthorhombic low-temperature (LT) phase, implying three different twin-domain orientations. The microstructure was generated by annealing HT-Ni3Sn2 considerably below the order-disorder transition temperature, establishing the LT phase avoiding too much domain coarsening. High-resolution electron microscopy reveals domain sizes of 100-200 Å compatible with the Scherrer broadening of the superstructure reflections recorded by X-ray diffraction. Whereas the orthorhombic symmetry of the LT phase leads in powder-diffraction patterns from coarse-domain size material to splitting of the fundamental reflections, this splitting does not occur for the LT-Ni3Sn2 with nanoscale domains. Instead, a (pseudo)hexagonal indexing is possible giving hexagonal lattice parameters, which are, however, incompatible with the positions of the superstructure reflections. This can be attributed to interference between X-rays scattered by the differently oriented, truly orthorhombic domains leading to merging of the fundamental reflections. These show pronounced anisotropic microstrain-like broadening, where the integral breadths ? on the reciprocal d-spacing scale of a series of higher order reflection increase in a non-linear fashion with upward curvature with the reciprocal d-spacings ? of these reflections. Such a type of unusual microstrain broadening appears to be typical for microstructures which are inhomogeneous on the nanoscale, and in which the structural inhomogeneities lead to small phase shifts of the scattered radiation from different locations (e.g. domains).

  13. InGaN/GaN quantum wells for polariton laser diodes: Role of inhomogeneous broadening

    SciTech Connect

    Glauser, Marlene; Mounir, Christian; Rossbach, Georg; Feltin, Eric; Carlin, Jean-François; Butté, Raphaël; Grandjean, Nicolas

    2014-06-21

    Contrary to the case of III-nitride based visible light-emitting diodes for which the inhomogeneous linewidth broadening characteristic of InGaN-based multiple quantum well (MQW) heterostructures does not appear as a detrimental parameter, such a broadening issue can prevent a microcavity (MC) system entering into the strong light-matter coupling regime (SCR). The impact of excitonic disorder in low indium content (x ∼ 0.1) In{sub x}Ga{sub 1–x}N/GaN MQW active regions is therefore investigated for the subsequent realization of polariton laser diodes by considering both simulations and optical characterizations. It allows deriving the requirements for such MQWs in terms of absorption, emission linewidth, and Stokes shift. Systematic absorption-like and photoluminescence (PL) spectroscopy experiments are performed on single and multiple In{sub 0.1}Ga{sub 0.9}N/GaN quantum wells (QWs). Micro-PL mappings reveal a low temperature PL linewidth of ∼30 meV, compatible with SCR requirements, for single QWs for which the microscopic origin responsible for this broadening is qualitatively discussed. When stacking several InGaN/GaN QWs, a departure from such a narrow linewidth value and an increase in the Stokes shift are observed. Various possible reasons for this degradation such as inhomogeneous built-in field distribution among the QWs are then identified. An alternative solution for the MC design to achieve the SCR with the InGaN alloy is briefly discussed.

  14. Line parameters for CO2 broadening in the ν2 band of HD16O

    NASA Astrophysics Data System (ADS)

    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.

    2017-01-01

    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.

  15. Nonempirical Simulations of Inhomogeneous Broadening of Electronic Transitions in Solution: Predicting Band Shapes in One- and Two-Photon Absorption Spectra of Chalcones.

    PubMed

    Bednarska, Joanna; Zaleśny, Robert; Tian, Guangjun; Murugan, Natarajan Arul; Ågren, Hans; Bartkowiak, Wojciech

    2017-09-30

    We have examined several approaches relying on the Polarizable Embedding (PE) scheme to predict optical band shapes for two chalcone molecules in methanol solution. The PE-TDDFT and PERI-CC2 methods were combined with molecular dynamics simulations, where the solute geometry was kept either as rigid, flexible or partly-flexible (restrained) body. The first approach, termed RBMD-PE-TDDFT, was employed to estimate the inhomogeneous broadening for subsequent convolution with the vibrationally-resolved spectra of the molecule in solution determined quantum-mechanically (QM). As demonstrated, the RBMD-PE-TDDFT/QM-PCM approach delivers accurate band widths, also reproducing their correct asymmetric shapes. Further refinement can be obtained by the estimation of the inhomogeneous broadening using the RBMD-PERI-CC2 method. On the other hand, the remaining two approaches (FBMD-PE-TDDFT and ResBMD-PE-TDDFT), which lack quantum-mechanical treatment of molecular vibrations, lead to underestimated band widths. In this study, we also proposed a simple strategy regarding the rapid selection of the exchange-correlation functional for the simulations of vibrationally-resolved one- and two-photon absorption spectra based on two easy-to-compute metrics.

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

    PubMed Central

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

    2013-01-01

    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. PMID:24052032

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

    PubMed

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

    2013-11-01

    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.

  18. Self-focusing and frequency broadening of laser pulse in water

    SciTech Connect

    Sati, Priti; Tripathi, V. K.; Verma, Updesh

    2014-11-15

    An analytical model for the avalanche breakdown of water by an intense short laser pulse of finite spot size is developed. Initially, the laser undergoes self-focusing due to Kerr nonlinearity. As it acquires large intensity, it causes heating and avalanche breakdown of water. The plasma thus created on the laser axis causes nonlinear refraction induced defocusing of the laser. Thermal conduction tends to flatten the temperature profile and reduce the nonlinear refraction. The plasma density modification leads to frequency broadening of the laser.

  19. On the Broadening of the Martensitic Transition in Heusler Alloys: From Microscopic Features to Magnetocaloric Properties

    NASA Astrophysics Data System (ADS)

    Cugini, F.; Porcari, G.; Rimoldi, T.; Orsi, D.; Fabbrici, S.; Albertini, F.; Solzi, M.

    2017-08-01

    We report on the sharpness of the magnetostructural transition in a Ni-Co-Mn-Ga-In Heusler alloy, which has a key role in defining the magnetocaloric effect exploitable in efficient and environmentally friendly magnetic refrigerators. Magnetic and calorimetric analysis together with optical microscopy in phase-imaging mode are compared to correlate the transition broadening with microscopic features of the sample. The three techniques give the same temperature behavior of the martensitic transition. Microscopy analysis of different sample areas and during cycles in temperature reveals the spatial homogeneity of the transition width and its reproducibility in subsequent transformations.

  20. Correlation effects in the theory of combined Doppler and pressure broadening. I - Classical theory

    NASA Technical Reports Server (NTRS)

    Ward, J.; Cooper, J.; Smith, E. W.

    1974-01-01

    An investigation is conducted of the combined effects of radiator-perturber collisions and radiator translational motion in the context of foreign gas broadening of optical transitions in neutral radiators. Questions concerning the speed-dependent collision frequency are considered and aspects of general theory are explored, taking into account the correlation function, the ensemble average, and the kinetic equation formalism. An elementary solution is discussed along with a one-perturber approximation, inverse power law model calculations, and a comparison with the Voigt profile.

  1. Broadening and Shifting of Atomic Strontium and Diatomic Bismuth Spectral Lines

    DTIC Science & Technology

    2003-05-01

    atomic barium . . . . . . . . 3-14 3-6. Line broadening cross sections of the O2 A band perturbed by helium, neon, argon, and krypton as a...perturbed by helium, neon, argon, and krypton as a function of the branch-independent quantum number . . . . . . . . . 3-20 m 3-8. Line...shifting cross sections of the atomic strontium 5s5p 3P0,1,2 5s6s 3S1 transitions around 14534 cm-1 perturbed by helium, neon, argon, krypton , and

  2. The Need for a National Alliance for Broadening Participation of Native Americans in the Geosciences.

    NASA Astrophysics Data System (ADS)

    Dalbotten, D. M.

    2008-12-01

    The continuing underrepresentation of Native Americans in the Geosciences can only mean that Native voices go unheard in setting research agendas and priorities. This is particularly significant where issues such as global climate change impact the land and livelihood of Native American communities. This talk will outline the need for a national alliance for broadening participation of Native Americans in the Geosciences. Our focus will be on defining goals for this alliance, i.e., new research in Geoscience education, defining best practices, inclusion of Native voices in Geoscience research, the potential for new collaborations, and promotion of opportunities for Native students and communities.

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

    SciTech Connect

    Wang, Yimeng; Zhang, Xinping Zhang, Jian; Liu, Hongmei

    2014-07-07

    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. Measurements of self-broadening of infrared absorption lines of ozone

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  5. VizieR Online Data Catalog: Stark broadening of H lines (Stehle 1995)

    NASA Astrophysics Data System (ADS)

    Stehle, C.

    1995-09-01

    Tables of Stark broadened hydrogen lines of the Lyman, Balmer and Paschen series are presented under the conditions of stellar envelopes. The formalism is based on the Model Microfield Method (MMM) (Brissaud and Frisch, Frisch and Brissaud 1971) for both the electronic and ionic contributions to the line shape. The range of temperatures is 10000 to 80000 K, and electronic densities between 3.2E+14 and 3.2E+16 cm-3. Lyman and Balmer results were published in A&AS 104, 509, whereas Paschen results were presented at the 1995 July Workshop in Vienna. (3 data files).

  6. Single-pulse and secondary echoes in systems with a large inhomogeneous broadening of NMR lines

    NASA Astrophysics Data System (ADS)

    Chigvinadze, J. G.; Mamniashvili, G. I.; Sharimanov, Yu. G.

    2004-10-01

    The equations for the nuclear magnetizations which describe the dynamics of nuclear spin-systems with strong Larmor and Rabi inhomogeneous broadenings of the NMR line under conditions of their nonequilibrium are obtained in the framework of the Mims transformation matrix method; these equations have been obtained previously by the statistical tensors method. As an example, the properties of the proton single-pulse echo and its secondary signals in a test material (silicone oil) coated on the surface of high-Tc superconducting-oxide powders and in metallic hydride are presented.

  7. Broadening of the FeX (6374 {\\AA}) profiles above the limb in a coronal hole

    NASA Astrophysics Data System (ADS)

    Hassler, D. M.; Moran, T. G.

    1994-10-01

    Profiles of the visible Fe X (6374 Å) coronal emission line as a function of height above the limb were obtained out to 1.16 solar radii in a coronal hole using the NSO/Sacramento Peak Observatory Coronagraph, Universal Spectrograph and a CCD camera. These are the first coronal line profiles obtained as a function of height in a coronal hole from the ground. Analysis of the line widths suggests a large component of nonthermal broadening which increases with height ranging from 40 to 60 km/s, depending upon the assumed temperature or thermal component of the profile.

  8. Angular Broadening: Effects of Nonzero, Spatially Varying Plasma Frequency Between the Source and Observer

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1998-01-01

    Angular broadening of radiation due to scattering by density irregularities is usually described using geometric optics (GO) or the parabolic wave equation (PWE) with the assumptions that the radiation frequency f greatly exceeds the local plasma frequency f(sub p0) or that f(sub p0)/f is constant along the path. These assumptions are inappropriate for many solar system radio phenomena. Here the PWE and GO formalisms are extended to treat angular broadening in plasmas with nonzero, spatially varying ratios, f(sub p0)(z)/f < 1. The new PWE results show that the correlation function, scattered angular spectrum, and other quantities are modified by inclusion of a denominator factor [1 - f(sup 2, sub p0)(z prime)/f prime] inside the path integral over z prime, while the mean-square scattering angle depends on both f(sub p0)(z)/f at the observer and the foregoing factor inside the path integral. The PWE and GO predictions for are identical and involve equivalent assumptions. Previous GO and PWE results are recovered in the limits that f(sub p0)(z prime)/f is constant or zero. The new PWE and GO results will permit more accurate calculation of angular broadening for solar system and astrophysical sources. Moreover and importantly, due to the PWE and GO results for being identical, previous GO analyses of in solar system contexts are essentially correct, except for the neglect of or minor deficiencies in the treatment of nonzero, spatially varying f(sub p0)/f effects. The identical GO and PWE results for and the form of the PWE equation for the correlation function raise questions as to whether diffraction is unimportant for angular broadening (under the usual PWE conditions). Future direct comparisons of the PWE predictions with angular spectra calculated using existing GO ray-tracing codes should answer these questions. Diffraction effects are probably important when the medium and turbulence are

  9. Stark broadening of halogen atom lines from (1 D) n p levels

    NASA Astrophysics Data System (ADS)

    Djurović, S.; Konjević, N.; Dimitrijević, M. S.

    1990-12-01

    We report results of a study of the Stark broadening of halogen atom lines from (1 D) n p levels. Wall stabilized arc is used as a plasma source. Electron densities 2.2 3.2×1022 m-3 are determined from the width of H α line and electron temperature 9300 10000 K from plasma composition data. The agreement with the results of simple semiclassical calculations is within the limits of the estimated errors of both experiment and theory. An explanation for the large discrepancy between theory and experiment detected for three BrI lines is offered.

  10. Self- and CO2-broadened line shape parameters for infrared bands of HDO

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Knowledge of CO2-broadened HDO line widths and their temperature dependence is required to interpret infrared spectra of the atmospheres of Mars and Venus. However, this information is currently absent in most spectroscopic databases. We have analyzed nine high-resolution, high signal-to-noise spectra of HDO and HDO+CO2 mixtures to obtain broadening coefficients and other line shape parameters for transitions of the ν2 and ν3 vibrational bands located at 7.13 and 2.70 μm, respectively. The gas samples were prepared by mixing equal amounts of high-purity distilled H2O and 99% enriched D2O. The spectra were recorded at different temperatures (255-296 K) using a 20.38 cm long coolable cell [1] installed in the sample compartment of the Bruker IFS125HR Fourier transform spectrometer at the Jet Propulsion Laboratory in Pasadena, CA. The retrieved HDO spectroscopic parameters include line positions, intensities, self- and CO2-broadened half-width and pressure-induced shift coefficients and the temperature dependences for CO2 broadening. These spectroscopic parameters were obtained by simultaneous multispectrum fitting [2] of the same interval in all nine spectra. A non-Voigt line shape with speed dependence was applied. Line mixing was also observed for several transition pairs. Preliminary results compare well with the few other measurements reported in the literature.[1] K. Sung et al., J. Mol. Spectrosc. 162, 124-134 (2010).[2] D. C. Benner et al., J. Quant. Spectrosc. Radiat Transfer 53, 705-721 (1995).The research performed at the College of William and Mary was supported by NASA’s Mars Fundamental Research Program (Grant NNX13AG66G). The research at Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, Langley Research Center, and Goddard Space Flight Center was conducted under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG is pleased to acknowledge support of this study by the

  11. Convergence of Legendre Expansion of Doppler-Broadened Double Differential Elastic Scattering Cross Section

    SciTech Connect

    Arbanas, Goran; Dunn, Michael E; Larson, Nancy M; Leal, Luiz C; Williams, Mark L

    2012-01-01

    Convergence properties of Legendre expansion of a Doppler-broadened double-differential elastic neutron scattering cross section of {sup 238}U near the 6.67 eV resonance at temperature 10{sup 3} K are studied. A variance of Legendre expansion from a reference Monte Carlo computation is used as a measure of convergence and is computed for as many as 15 terms in the Legendre expansion. When the outgoing energy equals the incoming energy, it is found that the Legendre expansion converges very slowly. Therefore, a supplementary method of computing many higher-order terms is suggested and employed for this special case.

  12. Deconvolution of 2D coincident Doppler broadening spectroscopy using the Richardson Lucy algorithm

    NASA Astrophysics Data System (ADS)

    Zhang, J. D.; Zhou, T. J.; Cheung, C. K.; Beling, C. D.; Fung, S.; Ng, M. K.

    2006-05-01

    Coincident Doppler Broadening Spectroscopy (CDBS) measurements are popular in positron solid-state studies of materials. By utilizing the instrumental resolution function obtained from a gamma line close in energy to the 511 keV annihilation line, it is possible to significantly enhance the quality of the CDBS spectra using deconvolution algorithms. In this paper, we compare two algorithms, namely the Non-Negativity Least Squares (NNLS) regularized method and the Richardson-Lucy (RL) algorithm. The latter, which is based on the method of maximum likelihood, is found to give superior results to the regularized least-squares algorithm and with significantly less computer processing time.

  13. Elemental analysis of positron affinitive site in materials by coincidence Doppler broadening spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagai, Y.; Tang, Z.; Ohkubo, H.; Takadate, K.; Hasegawa, M.

    2003-10-01

    Elemental analysis study of the positron affinitive nano-structures in materials by coincidence Doppler broadening method are presented: (1) defect free Cu nano-clusters embedded in Fe, (2) nano-voids in Fe covered with Cu atoms, and (3) solute clusters (GP zones) in Al alloys (Al-Ag and Al-Zn). By utilizing positron trapping not only in vacancy-type defects but also positron affinitive, defect-free nano-clusters embedded in materials, unique and exclusive information, such as defect structure, coherency, chemical composition, and so on, on the trapping sites can be obtained.

  14. Distribution of Chern number by Landau level broadening in Hofstadter butterfly

    NASA Astrophysics Data System (ADS)

    Yoshioka, Nobuyuki; Matsuura, Hiroyasu; Ogata, Masao

    2015-04-01

    We discuss the relationship between the quantum Hall conductance and a fractal energy band structure, Hofstadter butterfly, on a square lattice under a magnetic field. At first, we calculate the Hall conductance of Hofstadter butterfly on the basis of the linear responce theory. By classifying the bands into some groups with a help of continued fraction expansion, we find that the conductance at the band gaps between the groups accord with the denominators of fractions obtained by aborting the expansion halfway. The broadening of Landau levels is given as an account of this correspondance.

  15. The Broadening of Spectral Lines by Collisions with Neutral Hydrogen Atoms

    NASA Astrophysics Data System (ADS)

    Barklem, P. S.

    1998-10-01

    In this thesis the theory of collisional broadening by neutral hydrogen of Anstee and O'Mara (1991,1992,1995) for s-p and p-s transitions of neutrals is extended and applied to both p-d, d-p, d-f and f-d transitions of neutral atoms, and the broadening of transitions of ions. The interaction between a ground state hydrogen atom with a generic neutral atom, is considered using Rayleigh-Schrödinger perturbation theory. The usual second order expression for the interaction energy between the two atoms involves an infinite sum over virtual states of the two-atom system, and an energy denominator which is the energy debt incurred when the two atom system makes a transition from the state of interest to a virtual state. Unsöld (1927,1955) showed that the expression for the in teraction energy can be greatly simplified if the variable energy debt incurred in making a transition from the state of interest to a virtual state is replaced by a fixed debt Ep. Closure can then be used to complete the sum over the virtual states leading to an expression for the interaction energy in terms of diagonal matrix elements of V2 (where V is the electrostatic interaction between the two atoms), and Ep. This is commonly referred to as the Unsöld approximation. It is the most important approximation in the development of the treatment of spectral line broadening presented in this thesis. Expressions for the interaction energy between a ground state hydrogen atom and a generic neutral atom in both d- and f-states are presented. Adiabatic potential curves calculated from code written to compute these expressions are presented. For interactions of neutral atoms, the Unsöld value of Ep=-4/9 atomic units is used throughout. Code was written to compute line broadening cross-sections for p-d, d-p, d-f and f-d transitions of neutral atoms, using the semi-classical procedure of Roueff (1974) adapted for these transitions. Firstly, the dependence of cross-sections on regions of the potential

  16. Revisiting the Stark Broadening by fluctuating electric fields using the Continuous Time Random Walk Theory

    NASA Astrophysics Data System (ADS)

    Capes, H.; Christova, M.; Boland, D.; Catoire, F.; Godbert-Mouret, L.; Koubiti, M.; Mekkaoui, A.; Rosato, J.; Marandet, Y.; Stamm, R.

    2010-10-01

    Stark broadening of atomic lines in plasmas is calculated by modelling the plasma stochastic electric field using the CTRW approach [1,2]. This allows retaining non Markovian terms in the Schrödinger equation averaged over the electric field fluctuations. As an application we consider a special case of a non separable CTRW process, the so called Kangaroo process [3]. An analytic expression for the line profile is presented for arbitrary waiting time distribution functions. A preliminary application to the hydrogen Lyman α line is discussed.

  17. Remembering Collective Violence: Broadening the Notion of Traumatic Memory in Post-Conflict Rehabilitation.

    PubMed

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

    2016-12-01

    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.

  18. Ultrafast laser produced zinc plasma: Stark broadening of emission lines in nitrogen ambient

    SciTech Connect

    Rao, Kavya H.; Smijesh, N.; Nivas, Jijil JJ; Philip, Reji

    2016-04-15

    The effect of ambient pressure on Stark broadening of emission lines from neutrals and ions in an ultrafast laser (100 fs, 800 nm) produced zinc plasma is investigated. Measured spectra reveal that the full width at half maximum (δλ) of neutral lines remains unchanged in the pressure range of 10{sup −6} to 10{sup −1 }Torr, shows an even fluctuation in the pressure range of 0.1 to 100 Torr, and then increases with pressure. On the other hand, δλ of ion lines is nearly a constant from 10{sup −6} to 10{sup −3 }Torr, and then increases consistently with ambient pressure. A line narrowing of neutral emissions observed in the region of 1 to 100 Torr can be attributed to larger plasma temperatures, whereas the consistent increase in δλ with pressure seen for ion emission results from the prevalence of additional broadening mechanisms related to Coulomb interactions, ion-ion interaction, and Debye shielding. An accurate knowledge of emission line width is crucial for unambiguously calculating number density values for any given ambient pressure. Moreover, it can be relevant for the design of narrow line width, bright plasma sources for various applications.

  19. Music-induced positive mood broadens the scope of auditory attention

    PubMed Central

    Makkonen, Tommi; Eerola, Tuomas

    2017-01-01

    Abstract Previous studies indicate that positive mood broadens the scope of visual attention, which can manifest as heightened distractibility. We used event-related potentials (ERP) to investigate whether music-induced positive mood has comparable effects on selective attention in the auditory domain. Subjects listened to experimenter-selected happy, neutral or sad instrumental music and afterwards participated in a dichotic listening task. Distractor sounds in the unattended channel elicited responses related to early sound encoding (N1/MMN) and bottom-up attention capture (P3a) while target sounds in the attended channel elicited a response related to top-down-controlled processing of task-relevant stimuli (P3b). For the subjects in a happy mood, the N1/MMN responses to the distractor sounds were enlarged while the P3b elicited by the target sounds was diminished. Behaviorally, these subjects tended to show heightened error rates on target trials following the distractor sounds. Thus, the ERP and behavioral results indicate that the subjects in a happy mood allocated their attentional resources more diffusely across the attended and the to-be-ignored channels. Therefore, the current study extends previous research on the effects of mood on visual attention and indicates that even unfamiliar instrumental music can broaden the scope of auditory attention via its effects on mood. PMID:28460035

  20. Molecular dynamic simulations of N2-broadened methane line shapes and comparison with experiments

    NASA Astrophysics Data System (ADS)

    Le, Tuong; Doménech, José-Luis; Lepère, Muriel; Tran, Ha

    2017-03-01

    Absorption spectra of methane transitions broadened by nitrogen have been calculated for the first time using classical molecular dynamic simulations. For that, the time evolution of the auto-correlation function of the dipole moment vector, assumed along a C-H axis, was computed using an accurate site-site intermolecular potential for CH4-N2. Quaternion coordinates were used to treat the rotation of the molecules. A requantization procedure was applied to the classical rotation and spectra were then derived as the Fourier-Laplace transform of the auto-correlation function. These computed spectra were compared with experimental ones recorded with a tunable diode laser and a difference-frequency laser spectrometer. Specifically, nine isolated methane lines broadened by nitrogen, belonging to various vibrational bands and having rotational quantum numbers J from 0 to 9, were measured at room temperature and at several pressures from 20 to 945 mbar. Comparisons between measured and calculated spectra were made through their fits using the Voigt profile. The results show that ab initio calculated spectra reproduce with very high fidelity non-Voigt effects on the measurements and that classical molecular dynamic simulations can be used to predict spectral shapes of isolated lines of methane perturbed by nitrogen.

  1. Collisional broadening of Mg, Sr, Ca and Na resonance lines by atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Kerkeni, B.; Barklem, P. S.; Spielfiedel, A.; Feautrier, N.

    2004-02-01

    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. Experimental study of alkali-metal collisional line broadening for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Shindo, Francois

    2005-05-01

    The visible and near infrared spectra of L- and T-type brown dwarfs exhibit prominent resonance lines of alkali-metal atoms [1]. It is expected that such features are present in the spectra of extrasolar giant planets (EGPs) [2,3]. In the cool dwarfs, the most prominent alkali-features are due to the resonance lines of Na at 590 nm and of K at 770 nm, significantly broadened by collisions with H2 and He at temperatures around 1000 K. As this broadening is pressure and temperature sensitive, the resonance line profile can be used as a diagnostic of the atmospheric conditions of cool brown dwarfs and EGPs. To improve the data available for modeling, we have set up a spectroscopic experiment to measure absolute absorption coefficients of alkali vapors colliding with H2 and He at relevant temperatures. Our apparatus allows us to use the ``hook'' method to determine the atom number density of the alkali element. We will discuss our first spectroscopic measurements on the absorption of potassium vapors mixed with He buffer gas. This work is supported in part by NASA grant NAG5-12751. References: [1] ^ A. Burrows et al. 2002, ApJ, 573, 394 [2] S. Seager and D. D. Sasselov 2000, ApJ, 537, 916 [3] A. Sudarsky et al. 2003, ApJ, 588, 1121

  3. Experimental and Theoretical He-BROADENED Line Parameters of Carbon Monoxide in the Fundamental Band

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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

  4. Characterization of an Experimental Referee Broadened Specification (ERBS) aviation turbine fuel and ERBS fuel blends

    NASA Technical Reports Server (NTRS)

    Seng, G. T.

    1982-01-01

    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. Photo-induced brightening and broadening effects of gold quantum clusters

    NASA Astrophysics Data System (ADS)

    Huang, Hsiu-Ying; Lin, Chia-Hui; Lin, Cheng-An J.

    2016-04-01

    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.

  6. Origins of extreme broadening mechanisms in near-edge x-ray spectra of nitrogen compounds

    NASA Astrophysics Data System (ADS)

    Vinson, John; Jach, Terrence; Elam, W. T.; Denlinger, J. D.

    2014-11-01

    We demonstrate the observation of many-body lifetime effects in valence-band x-ray emission. A comparison of the N K α emission of crystalline ammonium nitrate to molecular-orbital calculations revealed an unexpected, extreme broadening of the NO σ recombination—so extensively as to virtually disappear. GW calculations establish that this disappearance is due to a large imaginary component of the self-energy associated with the NO σ orbitals. Building upon density-functional theory, we have calculated radiative transitions from the nitrogen 1 s level of ammonium nitrate and ammonium chloride using a Bethe-Salpeter method to include electron-hole interactions. The absorption and emission spectra of both crystals evince large, orbital-dependent sensitivity to molecular dynamics. We demonstrate that many-body effects as well as thermal and zero-point motion are vital for understanding observed spectra. A computational approach using average atomic positions and uniform broadening to account for lifetime and phonon effects is unsatisfactory.

  7. Beyond the Lorentzian Model in Quantum Transport: Energy-Dependent Resonance Broadening in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Liu, Zhenfei; Neaton, Jeffrey B.

    In quantum transport calculations, transmission functions of molecular junctions, as well as spectral functions of metal-organic interfaces, often feature peaks originating from molecular resonances. These resonance peaks are often assumed to be Lorentzian, with an energy-independent broadening function Γ. However, in the general case, the wide-band-limit breaks down, and the Lorentzian approximation is no longer valid. Here, we develop a new energy-dependent broadening function Γ (E) , based on diagonalization of non-Hermitian matrices within a non-equilbrium Green's function (NEGF) formalism. As defined, Γ (E) can describe resonances of non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively; and it is particularly useful in understanding transport properties in terms of molecular orbitals in asymmetric junctions. We compute this quantity via an ab initio NEGF approach based on density functional theory and illustrate its utility with several junctions of experimental relevance, including recent work on rectification in Au-graphite junctions. This work is supported by the DOE, and computational resources are provided by NERSC.

  8. Spectral broadening measurement of the lower hybrid waves during long pulse operation in Tore Supra

    NASA Astrophysics Data System (ADS)

    Berger-By, G.; Decampy, J.; Antar, G. Y.; Goniche, M.; Ekedahl, A.; Delpech, L.; Leroux, F.; Tore Supra Team

    2014-02-01

    On many tokamaks (C-Mod, EAST, FTU, JET, HT-7, TS), a decrease in current drive efficiency of the Lower Hybrid (LH) waves is observed in high electron density plasmas. The cause of this behaviour is believed to be: Parametric Instabilities (PI) and Scattering from Density Fluctuations (SDF). For the ITER LH system, our knowledge must be improved to avoid such effects and to maintain the LH current drive efficiency at high density. The ITPA IOS group coordinates this effort [1] and all experimental data are essential to validate the numerical codes in progress. Usually the broadening of the LH wave frequency spectrum is measured by a probe located in the plasma edge. For this study, the frequency spectrum of a reflected power signal from the LH antenna was used. In addition, the spectrum measurements are compared with the density fluctuations observed on RF probes located at the antenna mouth. Several plasma currents (0.6 to 1.4 MA) and densities up to 5.2 × 1019 m-3 have been realised on Tore Supra (TS) long pulses and with high injected RF power, up to 5.4 MW-30s. This allowed using a spectrum analyser to make several measurements during the plasma pulse. The side lobe amplitude, shifted by 20-30MHz with respect to the main peak, grows with increasing density. Furthermore, for an increase of plasma current at the same density, the spectra broaden and become asymmetric. Some parametric dependencies are shown in this paper.

  9. Si nanorod length dependent surface Raman scattering linewidth broadening and peak shift.

    PubMed

    Lin, Gong-Ru; Lin, Yung-Hsiang; Pai, Yi-Hao; Meng, Fan-Shuen

    2011-01-17

    Enhanced Stoke Raman scattering of large-area vertically aligned Si nanorod surface etched by metal-particle-catalytic is investigated. By enlarging the surface area with lengthening Si nanorods, the linear enhancement on Stoke Raman scattering intensity at 520 cm(-1) is modeled to show well correlation with increasing quantity of surface Si dangling bonds. With Si nanorod length increasing from 0.19 to 2.73 μm, the Raman peaks of the as-etched and oxidized samples gradually shift from -4 cm(-1) and from -4.5 cm(-1) associated with their linewidth broadening from 3 to 9 cm(-1) and from 7 to 18 cm(-1), respectively. The peak intensity of Raman scattering signal from Si nanorod could be enhanced with the increase of interaction area as the number of phonon mode directly corresponds to the tetrahedrally coordinated Si vibrations in the bulk crystal lattice. The asymmetric linewidth broadening and corresponding Raman peak shift is affected by the strained Si nanorod surface caused by etching and the crystal quality. Fourier transform infrared spectroscopy corroborates the dependency between nanorod length and Si-O-Si stretching mode absorption (at 1097 cm(-1)) on oxidized Si nanorod surface, elucidating the increased transformation of surface dangling bonds to Si-O-Si bonds for passivating Si nanorods and attenuating Stoke Raman scattering after oxidation.

  10. (abstract) Line Mixing Behavior of Hydrogen-Broadened Ammonia Under Jovian Atmospheric Conditions

    NASA Technical Reports Server (NTRS)

    Spilker, Thomas R.

    1994-01-01

    Laboratory spectral data reported last year have been used to investigate the line mixing behavior of hydrogen-broadened ammonia inversion lines. The data show that broadening parameters appearing in the modified Ben-Reuven opacity formalism of Berge and Gulkis (1976) cannot maintain constant values over pressure ranges that include low to moderate pressures and high pressures. Also, they cannot change drastically in value, as in the Spilker (1990) revision of the Berge and Gulkis formalism. It has long been recognized that at low pressures, less than about 1 bar of a Jovian atmospheric mixture, a VVW formalism yields more accurate predictions of ammonia opacity than Ben-Reuven formalisms. At higher pressures the Ben-Reuven formalisms are more accurate. Since the Ben-Reuven lineshape collapses to a VVW lineshape in the low pressure limit, this low pressure inaccuracy of the Ben-Reuven formalisms is surprising. By incorporating various behavior, a new formalism is produced that is more accurate than previous formalisms, particularly in the critical 'transition region' from 0.5 to 2 bars, and that can be used without discontinuity from pressures of zero to hundreds of bars. The new formalism will be useful in such applications as interpretation of radio astronomical and radio occultation data on giant planet atmospheres, and radiative transfer modeling of those atmospheres.

  11. Laser-induced plasma electron number density: Stark broadening method versus the Saha-Boltzmann equation

    NASA Astrophysics Data System (ADS)

    Arnab, Sarkar; Manjeet, Singh

    2017-02-01

    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.

  12. DISCOVERY OF SUBSTRUCTURE IN THE SCATTER-BROADENED IMAGE OF SGR A*

    SciTech Connect

    Gwinn, C. R.; Kovalev, Y. Y.; Soglasnov, V. A.

    2014-10-10

    We have detected substructure within the smooth scattering disk of the celebrated Galactic center radio source Sagittarius A* (Sgr A*). We observed this structure at 1.3 cm wavelength with the Very Long Baseline Array together with the Green Bank Telescope, on baselines of up to 3000 km, long enough to completely resolve the average scattering disk. Such structure is predicted theoretically as a consequence of refraction by large-scale plasma fluctuations in the interstellar medium. Along with the much-studied θ{sub d}∝λ{sup 2} scaling of angular broadening θ{sub d} with observing wavelength λ, our observations indicate that the spectrum of interstellar turbulence is shallow with an inner scale larger than 300 km. The substructure is consistent with an intrinsic size of about 1 mas at 1.3 cm wavelength, as inferred from deconvolution of the average scattering. Further observations of the substructure can set stronger constraints on the properties of scattering material and on the intrinsic size of Sgr A*. These constraints will guide our understanding of the effects of scatter broadening and the emission physics near the black hole in images with the Event Horizon Telescope at millimeter wavelengths.

  13. Broadening Participation of Women and Underrepresented Minorities in STEM through a Hybrid Online Transfer Program

    PubMed Central

    Drew, Jennifer C.; Galindo-Gonzalez, Sebastian; Ardissone, Alexandria N.; Triplett, Eric W.

    2016-01-01

    The Microbiology and Cell Science (MCS) Department at the University of Florida (UF) developed a new model of a 2 + 2 program that uses a hybrid online approach to bring its science, technology, engineering, and mathematics (STEM) curriculum to students. In this paradigm, 2-year graduates transfer as online students into the Distance Education in MCS (DE MCS) bachelor of science program. The program has broadened access to STEM with a steadily increasing enrollment that does not draw students away from existing on-campus programs. Notably, half of the DE MCS students are from underrepresented minority (URM) backgrounds and two-thirds are women, which represents a greater level of diversity than the corresponding on-campus cohort and the entire university. Additionally, the DE MCS cohort has comparable retention and academic performance compared with the on-campus transfer cohort. Of those who have earned a BS through the DE MCS program, 71% are women and 61% are URM. Overall, these data demonstrate that the hybrid online approach is successful in increasing diversity and provides another viable route in the myriad of STEM pathways. As the first of its kind in a STEM field, the DE MCS program serves as a model for programs seeking to broaden their reach. PMID:27587859

  14. Photosensitivity of reflection notch tuning and broadening in polymer stabilized cholesteric liquid crystals.

    PubMed

    Lee, Kyung Min; Tondiglia, Vincent P; White, Timothy J

    2016-01-28

    The position or bandwidth of the selective reflection of polymer stabilized cholesteric liquid crystals (PSCLCs) prepared from negative dielectric anisotropy ("-Δε") liquid crystalline hosts can be shifted by applying a DC voltage. The underlying mechanism of the tuning or broadening of the reflection of PSCLCs detailed in these recent efforts is ion-facilitated, electromechanical deformation of the structurally chiral, polymer stabilizing network in the presence of a DC bias. Here, we show that these electro-optic responses can also be photosensitive. The photosensitivity is most directly related to the presence of photoinitiator, which is a known ionic contaminant to liquid crystal devices. Measurement of the ion density of a series of control compositions before, during, and after irradiation with UV light confirms that the ion density in compositions that exhibit photosensitivity is increased by irradiation and correlates to not only the concentration of the photoinitiator but also the type. Thus, the magnitude of the electrically tuned or broadened reflection of PSCLC of certain compositions when subjected to DC field is further increased in the presence of UV light. While interesting and potentially useful in applications such as architectural windows, the effect may be deleterious to some device implementations. Accordingly, compositions in which photosensitivity is not observed are identified.

  15. New peak broadening parameter for the characterization of separation capability in capillary electrophoresis.

    PubMed

    Sursyakova, Viktoria V; Rubaylo, Anatoly I

    2015-02-01

    The influence of separation conditions on peak broadening is usually estimated by the number of theoretical plates. Using the data available in literature and experimental data, it is shown that in pressure-assisted capillary electrophoresis the plate number is not directly related to the separation capability of conditions used. The experiments at different electrolyte flow velocities demonstrate that a higher plate number (the best separation efficiency) can be obtained with a lower peak resolution. Since ions are separated by electrophoresis due to the difference in electrophoretic mobilities, the peak width in terms of electrophoretic mobility is suggested as a new peak broadening parameter describing the separation capability of the conditions used. The parameter can be calculated using the tailing factor and the temporal peak width at 5% of the peak height. A simple equation for the resolution calculation is derived using the parameter. The advantage of the peak width in terms of mobility over other parameters is shown. The new parameter is recommended to be used not only in pressure-assisted capillary electrophoresis but also in general capillary electrophoresis when in a number of runs the virtual separative migration distance and separation capability of the conditions used change widely.

  16. Quasiparticle Lifetime Broadening in Resonant X-ray Scattering of NH4NO3

    PubMed Central

    Vinson, John; Jach, Terrence; Müller, Matthias; Unterumsberger, Rainer; Beckhoff, Burkhard

    2016-01-01

    It has been previously shown that two effects cause dramatic changes in the x-ray absorption and emission spectra from the N K edge of the insulating crystal ammonium nitrate. First, vibrational disorder causes major changes in the absorption spectrum, originating not only from the thermal population of phonons, but, significantly, from zero-point motion as well. Second, the anomalously large broadening (~ 4 eV) of the emission originating from nitrate σ states is due to unusually short lifetimes of quasiparticles in an otherwise extremely narrow band. In this work we investigate the coupling of these effects to core and valence excitons that are created as the initial x-ray excitation energy is progressively reduced toward the N edge. Using a GW/Bethe-Salpeter approach, we show the extent to which this anomalous broadening is captured by the GW approximation. The data and calculations demonstrate the importance that the complex self-energies (finite lifetimes) of valence bands have on the interpretation of emission spectra. We produce a scheme to explain why extreme lifetimes should appear in σ states of other similar compounds. PMID:27747308

  17. The assembly of ant-farmed gardens: mutualism specialization following host broadening.

    PubMed

    Chomicki, Guillaume; Janda, Milan; Renner, Susanne S

    2017-03-15

    Ant-gardens (AGs) are ant/plant mutualisms in which ants farm epiphytes in return for nest space and food rewards. They occur in the Neotropics and Australasia, but not in Africa, and their evolutionary assembly remains unclear. We here use phylogenetic frameworks for important AG lineages in Australasia, namely the ant genus Philidris and domatium-bearing ferns (Lecanopteris) and flowering plants in the Apocynaceae (Hoya and Dischidia) and Rubiaceae (Myrmecodia, Hydnophytum, Anthorrhiza, Myrmephytum and Squamellaria). Our analyses revealed that in these clades, diaspore dispersal by ants evolved at least 13 times, five times in the Late Miocene and Pliocene in Australasia and seven times during the Pliocene in Southeast Asia, after Philidris ants had arrived there, with subsequent dispersal between these two areas. A uniquely specialized AG system evolved in Fiji at the onset of the Quaternary. The farming in the same AG of epiphytes that do not offer nest spaces suggests that a broadening of the ants' plant host spectrum drove the evolution of additional domatium-bearing AG-epiphytes by selecting on pre-adapted morphological traits. Consistent with this, we found a statistical correlation between the evolution of diaspore dispersal by ants and domatia in all three lineages. Our study highlights how host broadening by a symbiont has led to new farming mutualisms.

  18. High-resolution TALIF measurements of atomic oxygen: determination of gas temperature and collisional broadening coefficients

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul; Marinov, Daniil; Guaitella, Olivier; Drag, Cyril; Engeln, Richard; Golda, Judith; Schultz-von der Gathern, Volker

    2016-09-01

    Two-photon Absorption Laser-Induced Fluorescence (TALIF) is a well-established technique to measure relative (and with appropriate calibration techniques, absolute) densities of atoms in plasmas and flames. The excitation line profiles can provide additional information, but this is usually overlooked due to the mediocre spectral resolution of commercial pulsed dye laser systems. We have investigated O-atom TALIF excitation line profiles using a house-built narrow line-width pulsed UV laser system, based on pulsed Ti:Sa ring laser seeded by a cw infrared diode laser. The observed Doppler profiles allow unambiguous measurement of gas temperature with high precision in O2 and CO2 DC glow discharges. Sub-Doppler measurements, performed by reflecting the laser beam back through excitation zone, allow the pressure-broadened line shapes to be observed, both in a pure O2 DC discharge (up to 10 Torr pressure) and in an atmospheric pressure RF plasma jet in He/O2. Pressure broadening coefficients of the 3p3PJ state of O were determined for O2 and He bath gases, and were found to be an order of magnitude bigger than that predicted from the measured quenching rate. Work performed in the LABEX Plas@par project, with financial state aid (ANR-11-IDEX-0004-02 and ANR-13-BS09-0019).

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

    PubMed

    Singh, Mohar; Bisht, Ishwari Singh; Kumar, Sandeep; Dutta, Manoranjan; Bansal, Kailash Chander; Karale, Moreshwar; Sarker, Ashutosh; Amri, Ahmad; Kumar, Shiv; Datta, Swapan Kumar

    2014-01-01

    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.

  20. Global Wild Annual Lens Collection: A Potential Resource for Lentil Genetic Base Broadening and Yield Enhancement

    PubMed Central

    Singh, Mohar; Bisht, Ishwari Singh; Kumar, Sandeep; Dutta, Manoranjan; Bansal, Kailash Chander; Karale, Moreshwar; Sarker, Ashutosh; Amri, Ahmad; Kumar, Shiv; Datta, Swapan Kumar

    2014-01-01

    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. PMID:25254552

  1. A Bichromator for High Time Resolution Measurements of Stark Broadened Pellet Ablation Light

    NASA Astrophysics Data System (ADS)

    Schmidt, G. L.; Baylor, L. R.; Fehling, D. T.; Jernigan, T. C.; Brooks, N. H.; Parks, P. B.

    2004-11-01

    Details of the pellet/plasma interaction are important for modeling of local pellet source rates and cross field transport of pellet mass. Understanding these processes is critical for projection of current fueling experiments to future devices such as ITER. Measurement of the Stark broadened deuterium emission lines provides the electron density and temperature of the pellet cloud for comparison with modeling details. Stark broadening measurements on JET for low field launch pellets at moderate time resolution indicate a slow variation in the cloud parameters. Observations of ablation light suggest changes in cloud parameters may occur on faster time scales. We report on the possible application of a multiple interference filter technique[1]to allow monitoring of cloud parameters at time resolution sufficient to study both the slow and rapid variations in cloud parameters. Application of the bichromator to line widths and temporal evolution typical of DIII-D pellet injection cases will be discussed.[1]McNeill,D.H.,RSI 73 (2002) 3193.

  2. Competition of phase-breaking and thermal broadening in few-mode mesoscopic rings

    NASA Astrophysics Data System (ADS)

    Espe Hansen, Adam; Kristensen, Anders; Pedersen, Simon; Sorensen, Claus; Lindelof, Poul Erik

    2001-03-01

    The electron phase coherence length L_φ is measured in a ballistic few-mode ring interferometer. For the first time, it is demonstrated that the phase-breaking rate of the n'th harmonic h/ne of the Aharonov-Bohm (AB) magnetoconductance oscillations depends on temperature T like n\\cdot L/L_φ(T), hence scales with the actual pathlength n\\cdot L. Here L is half the ring circumference. To obtain this result, it is necessary to account for the effect of thermal broadening, which depends on the phase-shifts of the AB oscillations. The even harmonics h/2ne are found to be less affected by thermal broadening than the odd harmonics h/(2n+1)e, which can be understood in terms of a simple argument, resembling the argument explaining the h/2e Aharonov-Altshuler-Spivak oscillations in disordered systems. The rings are fabricated by shallow wet-etching in GaAs/GaAlAs heterostructures. The phase coherence length is found to vary as T-1 in the temperature regime from 0.3 K to 4 K, and is estimated to be of the order of 30 μ m at T = 0.3 K.

  3. Magnetic Turbulence and Line Broadening in Simulations of Lyman-Alpha Absorption

    NASA Astrophysics Data System (ADS)

    Gurvich, Alex; Burkhart, Blakesley K.; Bird, Simeon

    2016-01-01

    We use the Illustris cosmological AREPO simulations to study the effects of gas turbulence and magnetic fields on measurements from the Lyman-Alpha forest. We generate simulated Lyman-Alpha spectra and plot the distributions of Column Density (CDD) and Doppler Width (b) both by adhering to the canonical method of fitting Voigt profiles to absorption lines and by directly measuring the column density and equivalent widths from snapshot data .We investigate the effects of additional unresolved gas turbulence in Illustris by adding an additional broadening term to the line profiles to mimic turbulent broadening. When we do this, we find a measurable effect in the CDD and an offset in the mean of the b distribution corresponding to the additional turbulence. We also compare different MHD runs in AREPO we find that the CDD can measurably differentiate between magnetic seed field at redshifts as low as z=0.1, but we do not find that the b distribution is affected at a detectable level. Our work suggests that the effects of turbulence and magnetic fields from z=2-0.1 can potentially be measured with these diagnostics. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  4. Theoretical study of the Stark broadening for Mg IV spectral lines of astrophysical interest

    NASA Astrophysics Data System (ADS)

    de Andrés-García, I.; You, C.; Alonso-Medina, A.; Colón, C.

    2016-11-01

    Emission lines of Mg IV have been detected in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of LS V +46°21 star and in the Space Telescope Imaging Spectrograph (STIS) spectrum of BD +28°4211 star. This fact justifies our interest in providing spectroscopic parameters of Mg IV. Stark broadening parameters for 169 spectral lines of Mg IV have been calculated by using the Griem semi-empirical approach. The matrix elements used in these calculations has been determined from 13 configurations of Mg IV: 2s12p6, 2s22p4ns (n = 3-5), 2s22p4nd (n = 3-5) and 2s22p45g for even parity and 2s22p5, 2s22p4np (n = 3, 4) and 2s22p4nf (n = 4, 5) for odd parity. Our calculations were made by using the Cowan code. Data are presented for an electron density of 1017 cm-3 and temperatures T = 1.0-10.0 (104 K). Also we present calculated values of transition probabilities for 30 spectral lines and radiative lifetimes corresponding to its upper levels. These values were analysed using the data found in the literature. Theoretical trends of the Stark broadening parameters versus the temperature for several lines of astrophysical interest are presented.

  5. Action-potential broadening and endogenously sustained bursting are substrates of command ability in a feeding neuron of Pleurobranchaea.

    PubMed

    Gillette, R; Gillette, M U; Davis, W J

    1980-03-01

    1. The ventral white cells (VWC's) of the buccal ganglion of Pleurobranchaea, so named for their position and color, are a bilateral pair of neuron somata. Each sends a single axon out its contralateral stomatogastric nerve and has a dendritic field originating close to the soma. 2. The vwcs exhibit spontaneous episodes of prolonged depolarization (duration 1--4 min) accompanied by repetitive action-potential activity and separated by regular intervals of 3--30 min. Such prolonged burst episodes can be triggered by short pulses of depolarizing current. During the repetitive activity of the spontaneous bursts or that driven by imposed depolarization, the action potentials progressively broaden to 5--16 times their initial duration. 3. During spontaneous bursting or activity driven by imposed depolarization, the cyclic motor output of the feeding network is initiated or accelerated with a latency corresponding with the development of appreciable VWC spike broadening. When broadening of antidromic VWC spikes is suppressed by imposed hyperpolarization of the soma, the frequency of feeding cycles is significantly lower than when broadened spikes are allowed to develop. When trains of spikes are driven by depolarizing current, the motor output of the feeding network is not initiated until the VWC spikes have broadened to a repeatable "threshold" duration, regardless of the intensity of the depolarizing current. 4. The endogenous production of prolonged burst episodes, triggered by depolarizing current pulses, and progressive spike broadening can be demonstrated in the surgically isolated VWC soma. 5. The paired VWCs are strongly electrically coupled and display highly synchronous activity. They receive synaptic inputs from many previously identified interneurons of the feeding network and are thus reciprocally coupled within the network. 6. These results demonstrate that the capacity of this neuron to generate broadened action potentials during repetitive activity

  6. Line broadening of excimers bound to the surface of 4He clusters investigated by comparison with corona discharge excitation spectra

    NASA Astrophysics Data System (ADS)

    Mendoza-Luna, Luis Guillermo; Watkins, Mark; von Haeften, Klaus; Bonifaci, Nelly; Aitken, Frederic

    2013-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  8. Effect of broadened-specification fuels on aircraft engines and fuel systems

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.

    1979-01-01

    A wide variety of studies on the potential effects of broadened-specification fuels on future aircraft engines and fuel systems are summarized. The compositions and characteristics of aircraft fuels that may be derived from current and future crude-oil sources are described, and the most critical properties that may affect aircraft engines and fuel systems are identified and discussed. The problems that are most likely to be encountered because of changes in selected fuel properties are described; and the related effects on engine performance, component durability and maintenance, and aircraft fuel-system performance are discussed. The ability of current technology to accept possible future fuel-specification changes is discussed, and selected technological advances that can reduce the severity of the potential problems are illustrated.

  9. Interaction of runaway electrons with lower hybrid waves via anomalous Doppler broadening

    NASA Astrophysics Data System (ADS)

    Martín-Solís, J. R.; Sánchez, R.; Esposito, B.

    2002-05-01

    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.

  10. A partial oxidation staging concept for gas turbines using broadened specification fuels

    NASA Technical Reports Server (NTRS)

    Clayton, R. M.

    1979-01-01

    A concept is described for using a very fuel-rich partial oxidation process as the first stage of a two-stage combustion system for onboard processing of broadened specification fuels to improve their combustion characteristics. Results of an initial step in the experimental verification of the concept are presented, where the basic benefits of H2 enrichment are shown to provide extended lean-combustion limits and permit simultaneous achievement of ultralow levels of NOx, CO, and HC emissions. The H2 required to obtain these results is within the range available from a partial oxidation precombustion stage. Operation of a catalytic partial oxidation reactor using a conventional aviation turbine fuel (JP5) and an unconventional fuel (blend of JP5/xylene) is shown to produce a 'fuel gas' stream with near-theoretical equilibrium H2 content. However, a number of design considerations indicate that the precombustion stage should be incorporated as a thermal reaction.

  11. Natural widths and blackbody radiation induced shift and broadening of Rydberg levels in magnesium ions

    NASA Astrophysics Data System (ADS)

    Glukhov, Igor L.; Mokhnenko, Sergey N.; Nikitina, Elizaveta A.; Ovsiannikov, Vitaly D.

    2015-01-01

    Theoretical analysis is presented of the natural lifetimes and blackbody-radiation (BBR)-induced shifts and widths of Rydberg states with small and large angular momenta l. Asymptotic presentations in elementary functions are derived for matrix elements of bound-bound, bound-free and threshold radiative transitions from hydrogenic-type states with large angular momenta, applicable to both hydrogen-like and many-electron atoms and ions. For states with small angular momenta two numerical methods based on the quantum defects were used and corresponding data are compared with one another and with the most reliable data of the literature. Asymptotic approximations are derived for natural lifetimes, thermal shifts and broadening of Rydberg states of small and high l and principal quantum numbers n ≫ 1.

  12. Nonlinear interference effects and all-optical switching in optically dense inhomogeneously broadened media

    SciTech Connect

    Popov, A.K.; Myslivets, S.A.; George, Thomas F.

    2005-04-01

    Specific features of nonlinear interference processes at quantum transitions in near- and fully resonant Doppler-broadened optically dense media are studied. The possibility of all-optical switching of the medium to opaque or, alternatively, to absolutely transparent, or even to strongly amplifying states is explored, which is controlled by a small variation of two driving or probe radiations and does not require any change of the level populations. Optimum conditions for inversionless amplification of short-wavelength radiation above the oscillation threshold at the expense of the longer-wavelength control fields are investigated. The feasibility of overcoming the fundamental limitation on a velocity-interval of resonantly coupled molecules imposed by the Doppler effect is shown, based on quantum coherence.

  13. Stark broadening of high-principal-quantum-number n-alpha lines of hydrogen.

    NASA Technical Reports Server (NTRS)

    Lasalle, T. R.; Nee, T.-J.; Griem, H. R.

    1973-01-01

    High n-alpha lines (transitions n + 1 to n) with quantum numbers n between 50 and 250 have been observed emanating from galactic H II regions where the electron density and temperature are about 1000/cu cm and 1 eV, respectively. High n-alpha lines have not previously been seen in the laboratory where fairly homogeneous plasmas may be produced and relatively precise measurements of electron densities and temperatures can be made. The present work describes experiments where the first members of the hydrogen line series with lower states n = 10, 11, 12, and 13 have been detected in a laboratory plasma. The width of the 12-alpha line at 88.7 microns could be measured and was consistent with calculated broadening from elastic electron collisions and quasi-static ion effects.

  14. Broadening of mesophase temperature range induced by doping calamitic mesogen with banana-shaped mesogen

    NASA Astrophysics Data System (ADS)

    Cvetinov, Miroslav; Stojanović, Maja; Obadović, Dušanka; Vajda, Aniko; Fodor-Csorba, Katalin; Eber, Nandor

    2016-03-01

    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.

  15. Effects of Doppler broadening on Autler-Townes splitting in six-wave mixing

    SciTech Connect

    Niu Jinyan; Pei Liya; Lu Xiaogang; Wang Ruquan; Wu Lingan; Fu Panming

    2011-09-15

    The effects of Doppler broadening on Autler-Townes (AT) splitting in six-wave mixing (SWM) are investigated by the dressed-state model. We analyze the velocities at which the atoms are in resonance with the dressed states through Doppler frequency shifting and find that, depending on the wave-number ratio, there may be two resonant velocities which can originate from resonance with one of the dressed states or from resonance with two different dressed states. Based on this model, we discuss a novel type of AT doublet in the SWM spectrum, where macroscopic effects play an important role. Specifically, the existence of resonant peaks requires polarization interference between atoms of different velocities in addition to a change in the number of resonant atoms involved. Our model can also be employed to analyze electromagnetically induced transparency resonance and other types of Doppler-free high-resolution AT spectroscopy.

  16. Nitride superluminescent diodes with broadened emission spectrum fabricated using laterally patterned substrate.

    PubMed

    Kafar, A; Stanczyk, S; Sarzynski, M; Grzanka, S; Goss, J; Targowski, G; Nowakowska-Siwinska, A; Suski, T; Perlin, P

    2016-05-02

    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.

  17. Collision broadening effect upon tropospheric temperature calibration functions for pure rotational Raman lidars

    NASA Astrophysics Data System (ADS)

    Gerasimov, V. V.; Zuev, V. V.; Pravdin, V. L.; Nakhtigalova, D. P.; Pavlinskiy, A. V.

    2015-11-01

    We present the general calibration function for temperature retrievals in the cloud-free troposphere using pure rotational Raman (PRR) lidars under the condition of the laser-beam receiver-field-of-view complete overlap. The function is derived within the framework of the semiclassical theory and takes account of the broadened by collision effects elastic backscattered signal leakage into the nearest (to the laser line) lidar PRR channel. The two simplest nonlinear special cases of the general calibration function are considered to be applied in the temperature retrieval algorithm. The vertical temperature profiles retrieved from nighttime lidar measurements in Tomsk (56.48°N, 85.05°E), on October 2, 2014, are given as an example. The measurements were performed using a PRR lidar designed in Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS) for lower-atmosphere temperature-profile retrievals.

  18. Effect of collisional lines broadening and calibration functions in the pure rotational Raman lidar technique

    NASA Astrophysics Data System (ADS)

    Gerasimov, Vladislav V.; Zuev, Vladimir V.

    2016-10-01

    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).

  19. Coincidence Doppler broadening study of Eurofer 97 irradiated in spallation environment

    NASA Astrophysics Data System (ADS)

    Sabelová, V.; Kršjak, V.; Kuriplach, J.; Dai, Y.; Slugeň, V.

    2015-03-01

    The behavior of transmutation helium during isochronal annealing of irradiated Eurofer 97 was investigated using coincidence Doppler broadening spectroscopy (CDBS). The investigated ferritic martensitic steel was irradiated in 2000 and 2001 in the frame of the STIP-II project at the Swiss neutron spallation source (SINQ) (irradiation with neutrons and protons) at the Paul Scherrer Institute (PSI). During isochronal annealing experiment, coarsening of vacancy clusters and/or growth of helium bubbles was observed at T ⩾ 500 °C. This process causes an increase of low-momentum annihilation events and related increase of the S parameter during thermal treatment of material. On the other hand, the maximum concentration of helium in small vacancy clusters (Vn) was observed after annealing at 400 °C, where an excellent correlation with the calculated CDBS profiles of Vn + Hem clusters was found.

  20. Effect of broadened-specification fuels on aircraft engines and fuel systems

    NASA Technical Reports Server (NTRS)

    Rudey, R. A.

    1979-01-01

    A wide variety of studies on the potential effects of broadened-specification fuels on future aircraft engines and fuel systems are summarized. The compositions and characteristics of aircraft fuels that may be derived from current and future crude-oil sources are described, and the most critical properties that may effect aircraft engines and fuel systems are identified and discussed. The problems that are most likely to be encountered because of changes in selected fuel properties are explored; and the related effects on engine performance, component durability and maintenance, and aircraft fuel-system performance are examined. The ability of current technology to accept possible future fuel specification changes is assessed and selected technological advances that can reduce the severity of the potential problems are illustrated.

  1. Creation of problem-dependent Doppler-broadened cross sections in the KENO Monte Carlo code

    DOE PAGES

    Hart, Shane W. D.; Celik, Cihangir; Maldonado, G. Ivan; ...

    2015-11-06

    In this paper, we introduce a quick method for improving the accuracy of Monte Carlo simulations by generating one- and two-dimensional cross sections at a user-defined temperature before performing transport calculations. A finite difference method is used to Doppler-broaden cross sections to the desired temperature, and unit-base interpolation is done to generate the probability distributions for double differential two-dimensional thermal moderator cross sections at any arbitrarily user-defined temperature. The accuracy of these methods is tested using a variety of contrived problems. In addition, various benchmarks at elevated temperatures are modeled, and results are compared with benchmark results. Lastly, the problem-dependentmore » cross sections are observed to produce eigenvalue estimates that are closer to the benchmark results than those without the problem-dependent cross sections.« less

  2. Cross Functional Career Navigation: The Way to Broaden Your Career Options

    NASA Astrophysics Data System (ADS)

    Greenhalgh, Todd

    2000-03-01

    In today's rapid paced global environment, broadening career options for career development depends on successful cross-functional career navigation. For scientists and engineers, this means developing a diversity of skills in addition to a strong technical foundation. Fortunately, companies use cross-functional teams as one of the key tools for rapidly developing and commercializing products and services. Participation on these teams carries with it the additional benefit of allowing an individual to develop new skills, and to gain valuable expertise in areas that are critical to the growth of their company, their industry and, most importantly, their career. This talk will outline some of the important cross functional skills that can propel your career ahead and ways in which you can take charge of your career mapping and enhance your value and employability.

  3. Alcoholism and memory: broadening the scope of alcohol-expectancy research.

    PubMed

    Goldman, M S; Brown, S A; Christiansen, B A; Smith, G T

    1991-07-01

    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.

  4. Theory and Simulations of Refractive Substructure in Resolved Scatter-broadened Images

    NASA Astrophysics Data System (ADS)

    Johnson, Michael D.; Gwinn, Carl R.

    2015-06-01

    At radio wavelengths, scattering in the interstellar medium distorts the appearance of astronomical sources. Averaged over a scattering ensemble, the result is a blurred image of the source. However, Narayan & Goodman and Goodman & Narayan showed that for an incomplete average, scattering introduces refractive substructure in the image of a point source that is both persistent and wideband. We show that this substructure is quenched but not smoothed by an extended source. As a result, when the scatter-broadening is comparable to or exceeds the unscattered source size, the scattering can introduce spurious compact features into images. In addition, we derive efficient strategies to numerically compute realistic scattered images, and we present characteristic examples from simulations. Our results show that refractive substructure is an important consideration for ongoing missions at the highest angular resolutions, and we discuss specific implications for RadioAstron and the Event Horizon Telescope.

  5. Inelastic collision processes in ozone and their relation to atmospheric pressure broadening

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The research task employs infrared double-resonance to determine rotational energy transfer rates and pathways, in both the ground and vibrationally excited states of ozone. The resulting data base will then be employed to test inelastic scattering theories and to assess intermolecular potential models, both of which are necessary for the systematization and prediction of infrared pressure-broadening coefficients, which are in turn required by atmospheric ozone monitoring techniques based on infrared remote sensing. In addition, observation of excited-state absorption transitions will permit us to improve the determination of the 2 nu(sub 3), nu(sub 1) + nu(sub 2), and 2 nu(sub 1) rotational constants and to derive band strengths for hot-band transitions involving these levels.

  6. Plasma density characterization at SPARC_LAB through Stark broadening of Hydrogen spectral lines

    NASA Astrophysics Data System (ADS)

    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.

    2016-09-01

    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.

  7. Band broadening in gel electrophoresis: scaling laws for the dispersion coefficient measured by FRAP.

    PubMed

    Tinland, B; Pernodet, N; Pluen, A

    1998-10-05

    We determined quantitatively the band broadening effect during gel electrophoresis by measuring the longitudinal dispersion coefficient Dx, with a fluorescence recovery after photobleaching setup, coupled to an electrophoretic cell. We carried out measurements as a function of the electric field, the average pore size, and the molecular length of DNA fragments. Our results are in good agreement with the predictions of the biased reptation model with fluctuations described by T. A. Duke et al. [(1992) Physics Review Letters, vol. 69, pp. 3260-3263]. This agreement is observed on single-stranded DNA [persistence length approximately equal to 4 nm; B. Tinland et al. (1997) Macromolecules, vol. 30, pp. 5763-5765] in polyacrylamide gels and on double-stranded DNA (persistence length approximately equal to 50 nm) in agarose gels, two systems where the ratio between the average pore size and the Kuhn length is larger than 1.

  8. The natural sediment regime in rivers: broadening the foundation for ecosystem management

    USGS Publications Warehouse

    Wohl, Ellen E.; Bledsoe, Brian P.; Jacobson, Robert B.; Poff, N. LeRoy; Rathburn, Sara L.; Walters, David M.; Wilcox, Andrew C.

    2015-01-01

    Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.

  9. Creation of problem-dependent Doppler-broadened cross sections in the KENO Monte Carlo code

    SciTech Connect

    Hart, Shane W. D.; Celik, Cihangir; Maldonado, G. Ivan; Leal, Luiz C.

    2015-11-06

    In this paper, we introduce a quick method for improving the accuracy of Monte Carlo simulations by generating one- and two-dimensional cross sections at a user-defined temperature before performing transport calculations. A finite difference method is used to Doppler-broaden cross sections to the desired temperature, and unit-base interpolation is done to generate the probability distributions for double differential two-dimensional thermal moderator cross sections at any arbitrarily user-defined temperature. The accuracy of these methods is tested using a variety of contrived problems. In addition, various benchmarks at elevated temperatures are modeled, and results are compared with benchmark results. Lastly, the problem-dependent cross sections are observed to produce eigenvalue estimates that are closer to the benchmark results than those without the problem-dependent cross sections.

  10. THEORY AND SIMULATIONS OF REFRACTIVE SUBSTRUCTURE IN RESOLVED SCATTER-BROADENED IMAGES

    SciTech Connect

    Johnson, Michael D.; Gwinn, Carl R.

    2015-06-01

    At radio wavelengths, scattering in the interstellar medium distorts the appearance of astronomical sources. Averaged over a scattering ensemble, the result is a blurred image of the source. However, Narayan and Goodman and Goodman and Narayan showed that for an incomplete average, scattering introduces refractive substructure in the image of a point source that is both persistent and wideband. We show that this substructure is quenched but not smoothed by an extended source. As a result, when the scatter-broadening is comparable to or exceeds the unscattered source size, the scattering can introduce spurious compact features into images. In addition, we derive efficient strategies to numerically compute realistic scattered images, and we present characteristic examples from simulations. Our results show that refractive substructure is an important consideration for ongoing missions at the highest angular resolutions, and we discuss specific implications for RadioAstron and the Event Horizon Telescope.

  11. [Effect of an anomalous broadening of the synchronization band after electric stimulation of heart tissues].

    PubMed

    Mazurov, M E

    1987-01-01

    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.

  12. Effects of 946-nm thermal shift and broadening on Nd3+:YAG laser performance

    NASA Astrophysics Data System (ADS)

    Seyed Ebrahim, Pourmand; Ghasem, Rezaei

    2015-12-01

    Spectroscopic properties of flashlamp pumped Nd3+:YAG laser are studied as a function of temperature in a range from -30 °C to 60 °C. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of 4F3/2 → 4I9/2 are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature. The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is, thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state. Project supported by Estahban Branch, Islamic Azad University.

  13. Model for interpreting Doppler broadened optical line emission measurements on axially symmetric plasma

    NASA Technical Reports Server (NTRS)

    Englert, G. W.; Patch, R. W.; Reinmann, J. J.

    1978-01-01

    A plasma model, previously developed to interpret neutral-particle analyzer measurements on E x B heating devices, is adapted to analyze Doppler broadened charge-exchange-neutral lines measured by an optical monochromator. Comparison of theoretical with experimental results indicates that azimuthal drift as well as cyclotron motion are quite influential in determining line shapes and widths, and thus important in temperature determination, even when the monochromator line of sight is intersecting the plasma axis of symmetry. At this central sighting position, however, results are quite insensitive to radial ion density distribution when time lag between the charge-exchange-excitation events and emission is neglected. Line shapes and widths obtained by sighting across chords of plasma at various distances from the plasma axis of symmetry indicate a strong dependence on time lag.

  14. The shape of spectral lines with combined impact and statistical broadenings

    NASA Astrophysics Data System (ADS)

    Hirono, M.; Nakazawa, T.

    1982-01-01

    An analytical development of a line shape factor applicable to the central line region out to the far wings is presented, noting that the Lorentz shape is included as a special case. A proportional formulation is found for the interaction energy between two molecules as an influence on the shape factors determined by the Lorentz formula and statistical theory. The composite line shape is then defined for dipole-dipole and dipole-quadrupole interaction and methods of approximation are considered. The profiles are shown to be symmetrical about the center, reduce to the Lorentz shape for nu=2, and vary by a nu-power of the given formulation in the far wings. The predictions are applied to experimental results for transmittance of NO at 1868.96/cm and the fundamental band of HCl broadened by CO2 and good agreement is demonstrated. Applicability is determined to be suitable for low pressures or frequencies in the region of the line center.

  15. RELATIVISTIC BROADENING OF IRON EMISSION LINES IN A SAMPLE OF ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Brenneman, Laura W.; Reynolds, Christopher S.

    2009-09-10

    We present a uniform X-ray spectral analysis of eight type-1 active galactic nuclei that have been previously observed with relativistically broadened iron emission lines. Utilizing data from the XMM-Newton European Photon Imaging Camera (EPIC-pn) we carefully model the spectral continuum, taking complex intrinsic absorption and emission into account. We then proceed to model the broad Fe K{alpha} feature in each source with two different accretion disk emission line codes, as well as a self-consistent, ionized accretion disk spectrum convolved with relativistic smearing from the inner disk. Comparing the results, we show that relativistic blurring of the disk emission is required to explain the spectrum in most sources, even when one models the full reflection spectrum from the photoionized disk.

  16. Comparisons between GRNTRN simulations and beam measurements of proton lateral broadening distributions

    NASA Astrophysics Data System (ADS)

    Mertens, Christopher; Moyers, Michael; Walker, Steven; Tweed, John

    Recent developments in NASA's High Charge 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. The new version of HZETRN based on Green function methods, GRNTRN, 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 scattering distributions with beam measurements taken at Loma Linda Medical University. The simulated and measured lateral proton distributions will be compared for a 250 MeV proton beam on aluminum, polyethylene, polystyrene, bone, iron, and lead target materials.

  17. Electron collisional broadening of isolated lines from multiply-ionized atoms.

    NASA Astrophysics Data System (ADS)

    Griem, H. R.; Ralchenko, Yu. V.

    2000-05-01

    Recent experimental and theoretical (both improved semiclassical and fully quantum-mechanical) line broadening calculations for B III and Ne VII Δn = 0 transitions with n = 2 and 3, respectively, are discussed. The disagreements by about a factor of 2 between the fully quantum-mechanically calculated and both measured and semiclassically calculated widths can be explained in terms of violations of validity criteria for the semiclassical calculations and nonthermal Doppler effects. Only the quantum calculations allow a clear separation of elastic and inelastic scattering contributions to the width. For B III, elastic scattering contributes about 30%, for Ne VII inelastic scattering dominates. This allows rather direct comparisons with benchmark electron-ion scattering experiments. Additional independent determinations of line widths for multiply-ionized, nonhydrogenic ions are called for, but meanwhile caution should be exercised in the use of corresponding semiclassically calculated widths, e.g., in opacity calculations or for plasma density diagnostics.

  18. Confinement and inhomogeneous broadening effects in the quantum oscillatory magnetization of quantum dot ensembles

    NASA Astrophysics Data System (ADS)

    Herzog, F.; Heedt, S.; Goerke, S.; Ibrahim, A.; Rupprecht, B.; Heyn, Ch; Hardtdegen, H.; Schäpers, Th; Wilde, M. A.; Grundler, D.

    2016-02-01

    We report on the magnetization of ensembles of etched quantum dots with a lateral diameter of 460 nm, which we prepared from InGaAs/InP heterostructures. The quantum dots exhibit 1/B-periodic de-Haas-van-Alphen-type oscillations in the magnetization M(B) for external magnetic fields B  >  2 T, measured by torque magnetometry at 0.3 K. We compare the experimental data to model calculations assuming different confinement potentials and including ensemble broadening effects. The comparison shows that a hard wall potential with an edge depletion width of 100 nm explains the magnetic behavior. Beating patterns induced by Rashba spin-orbit interaction (SOI) as measured in unpatterned and nanopatterned InGaAs/InP heterostructures are not observed for the quantum dots. From our model we predict that signatures of SOI in the magnetization could be observed in larger dots in tilted magnetic fields.

  19. Stark broadening and shift of neutral iodine lines and regularities for analogous transitions of halogene atoms

    NASA Astrophysics Data System (ADS)

    Djurović, S.; Konjević, N.

    1988-06-01

    We report results of an experimental study of the Stark broadening and shift of fourteen and eight neutral iodine lines, respectively, in a plasma wall stabilized arc. An electron density of about 2 × 1022 m-3 was determined from the width of Hα line, while an electron temperature about 9300 K was derived from plasma composition data. The agreement within 40% of both experimental Stark widths and shifts with results of simple theoretical approach by Dimitrijević and Konjević is found. Results of the investigation of similarities of neutral iodine Stark widths are in agreement with the study of Wiese and Konjević. Comparison of experimental Stark shift shows similar types of regularities. Comparisons of Stark widths along analogous transitions of halogene atoms show an increase of widths from fluorine to iodine. It has been demonstrated also that Stark shifts for the same transitions show similar behaviour.

  20. Plasmonic Nanoparticle-based Hybrid Photosensitizers with Broadened Excitation Profile for Photodynamic Therapy of Cancer Cells

    PubMed Central

    Wang, Peng; Tang, Hong; Zhang, Peng

    2016-01-01

    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. PMID:27725746

  1. Vascular memory: can we broaden the concept of the metabolic memory?

    PubMed Central

    2012-01-01

    Based on the results of recent randomized, controlled clinical trials and analyses of their follow-up periods the concept of metabolic memory cannot be restricted to antihyperglycaemic treatment only, rather it can be extended to lipid-lowering and antihypertensive treatment and even life-style modification. This broadened concept can be designated as vascular memory. According to this new concept, not only immediate and short-term but long-term effects of the metabolic and cardiovascular risk milieu are of great importance. Consequently, early and intensive lifestyle interventions, treatment of hyperglycaemia, lipid abnormalities and hypertension can result in beneficial effects on cardiovascular outcomes even in the long run. On the contrary, failing in target-oriented treatment from early detection of abnormalities can be associated with life-threatening cardiovascular events subsequently. Additional experimental studies are needed to characterize the exact pathomechanism of vascular memory and further clinical trials are also essential to explore its real clinical significance. PMID:22545680

  2. Improving target discrimination ability of active polarization imagers by spectral broadening.

    PubMed

    Thomas, Lijo; Boffety, Matthieu; Goudail, François

    2015-12-28

    Active polarization imagers using liquid crystal variable retarders (LCVR) usually operate at one given wavelength for the sake of polarimetric accuracy. However, this often requires to use narrowband filters which reduces the amount of light entering the system and thus the signal-to-noise ratio. For applications where good target/background discriminability (contrast) is required rather than polarimetric accuracy, this may not be the best choice. In this Article, we address contrast optimization in the case of broadband active polarimetric imaging for target detection applications. Through numerical and experimental studies, we show that broadening the spectrum of the light entering the system can increase the contrast between two regions of a scene. Furthermore, we show that this contrast can be further increased by taking into account the spectral dependence of the scene and of the polarimetric properties of the imaging system in the optimization of the measurement procedure.

  3. Spectroscopic Study of Air-Broadened Nitrous Oxide in the ν_3 Band

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

    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.

  4. The ability of the Coincidence Doppler Broadening Spectroscopy to characterize polymers containing different chemical elements

    NASA Astrophysics Data System (ADS)

    Yang, J.; Zhang, T.; Han, L. A.; Cao, X. Z.; Yu, R. S.; Wang, B. Y.

    2017-04-01

    Hydrocarbon polymers, O-containing, F-containing and Cl-containing polymers are comprehensively studied by Coincidence Doppler Broadening Spectroscopy (CDBS). It is shown that for polymers with different chemical structure, CDBS results can effectively distinguish polar groups C dbnd O, Csbnd Cl, and Csbnd F. For polymers with similar chemical structure, the intensity of the element-specific peak in the CDBS ratio curve is dependent not only on the fraction of free positrons, but also on the content of characteristic atom in polymer repeated unit, and the polarity of the polymer molecule. For polymers containing several different polar groups, such as PCTFE (Csbnd F & Csbnd Cl) and PFA (Csbnd F & C dbnd O), whether the element-specific peak appears or not depends on the amount of the polar groups and its positron capture ability. This work may provide insights into potential applications of CDBS for studying complex polymer systems.

  5. Bandwidth broadening and asymmetric softening of collective spin waves in magnonic crystals

    SciTech Connect

    Montoncello, F. Giovannini, L.

    2014-06-16

    We investigate the dependence on the applied field of the frequency/wavevector dispersion relations of collective spin waves in arrays of dots, close to a magnetic transition. In particular, we focus on the low frequency “soft” modes in three different cases: end modes in the transition between two different saturated states in ellipses, fundamental mode in the saturated-to-vortex transition in disks, and gyrotropic mode in the vortex-to-saturated transition in disks. Noteworthy, the spin waves with nonzero Bloch wavevector along the direction of the applied field happen to soften earlier than spin waves with a Bloch wavevector along different directions, and this feature is responsible for an asymmetric broadening of the bandwidth along the different lattice directions. This is particularly useful in magnonic/spin-logic device research, if different binary digits are associated to modes with the same cell function but different propagation directions.

  6. Determination of ion temperatures from Zeeman broadened spectral lines in the edge of Tore Supra

    SciTech Connect

    Klepper, C.C.; Isler, R.C.; Tobin, S.J.; Hogan, J.T.; Hess, W.R.

    1994-09-01

    The authors have examined a {sup 3}P {yields} {sup 3}S multiplet of C III in Tore Supra in order to assess the possibility of determining the ion temperatures from transitions where the Zeeman effect cannot be neglected compared to the Doppler broadening. The preliminary studies lead them to believe that with good quality data the temperatures can be determined within about 20% in the 20--30 eV range and within about 50% in the neighborhood of 5 eV by fitting the entire multiplet rather than a semi-isolated feature, even though certain parameters important for the analysis, such as polarization effects of the optics, are not well characterized. In order to quantify these conclusions more precisely, future work will concentrate on developing numerical fitting routines and on examining the validity of the assumption that the distribution function for low ionization stages is Maxwellian.

  7. Preliminary analysis of aircraft fuel systems for use with broadened specification jet fuels

    NASA Technical Reports Server (NTRS)

    Pasion, A. J.; Thomas, I.

    1977-01-01

    An analytical study was conducted on the use of broadened specification hydrocarbon fuels in present day aircraft. A short range Boeing 727 mission and three long range Boeing 747 missions were used as basis of calculation for one-day-per-year extreme values of fuel loading, airport ambient and altitude ambient temperatures with various seasonal and climatic conditions. Four hypothetical fuels were selected; two high-vapor-pressure fuels with 35 kPa and 70 kPa RVP and two high-freezing-point fuels with -29 C and -18 C freezing points. In-flight fuel temperatures were predicted by Boeing's aircraft fuel tank thermal analyzer computer program. Boil-off rates were calculated for the high vapor pressure fuels and heating/insulation requirements for the high freezing point fuels were established. Possible minor and major heating system modifications were investigated with respect to heat output, performance and economic penalties for the high freezing point fuels.

  8. Heat-induced darkening and spectral broadening in photodarkened ytterbium-doped fiber under thermal cycling.

    PubMed

    Söderlund, Mikko J; Montiel i Ponsoda, Joan J; Koplow, Jeffrey P; Honkanen, Seppo

    2009-06-08

    We study thermal bleaching of photodarkening-induced loss in a 20-microm core diameter, large-mode-area ytterbium-doped silica fiber. Pristine and photodarkened samples are subjected to thermal cycling pulses. Recovery of the photodarkened fiber absorption coefficient initiates at approximately 350 degrees C and complete recovery is reached at approximately 625 degrees C. However, prior to recovery, the photodarkened fiber exhibits further heat-induced increase of absorption loss. This increase of loss is attributed to both a permanent increase of loss-inducing color centers and a temperature-dependent broadening of the absorption spectrum. Post-irradiation heat-induced formation of color centers suggests the presence of an intermediate energy state in the near-infrared photochemical mechanism for photodarkening.

  9. Environmental broadening of the CTTS bands: the hexaammineruthenium(II) complex in aqueous solution.

    PubMed

    Yurenev, P V; Kretov, M K; Scherbinin, A V; Stepanov, N F

    2010-12-16

    Cluster ab initio quantum chemistry approach is developed to simulate the charge-transfer-to-solvent (CTTS) absorption band and satellite ligand field bands of hexaammineruthenium(II) ion in aqueous solution. Several cluster models, including 16, 21, and 38 water molecules, are explored for this purpose. TDDFT method with long-range corrected BLYP (LC-BLYP) functional is used to obtain the vertical transition characteristics, and DFT B3LYP is used for calculation of the ground state geometry and vibrational frequencies of the solvated complex. A simple harmonic bath model is employed to estimate the absorption bandwidths and coherence decay times with the parameters taken from the quantum chemistry calculations. The present approach provides rather reasonable estimates for the CTTS band position and shape, also giving an additional insight for the mechanism of the CTTS band broadening.

  10. Plasmonic Nanoparticle-based Hybrid Photosensitizers with Broadened Excitation Profile for Photodynamic Therapy of Cancer Cells

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Tang, Hong; Zhang, Peng

    2016-10-01

    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.

  11. Surface hopping with a manifold of electronic states. III. Transients, broadening, and the Marcus picture

    SciTech Connect

    Dou, Wenjie; Subotnik, Joseph E.; Nitzan, Abraham

    2015-06-21

    In a previous paper [Dou et al., J. Chem. Phys. 142, 084110 (2015)], we have introduced a surface hopping (SH) approach to deal with the Anderson-Holstein model. Here, we address some interesting aspects that have not been discussed previously, including transient phenomena and extensions to arbitrary impurity-bath couplings. In particular, in this paper we show that the SH approach captures phonon coherence beyond the secular approximation, and that SH rates agree with Marcus theory at steady state. Finally, we show that, in cases where the electronic tunneling rate depends on nuclear position, a straightforward use of Marcus theory rates yields a useful starting point for capturing level broadening. For a simple such model, we find I-V curves that exhibit negative differential resistance.

  12. Influence of Impact Broadening on the CP Stars Spectra %t Uticaj sudarnog sirenja na spektre CP zvezda

    NASA Astrophysics Data System (ADS)

    Milovanovic, N.

    2004-09-01

    Stark broadening of spectral lines is dominant pressure broadening mechanism in hot, early-type, stars and white dwarf atmospheres. This type of broadening might also be important even in interstellar molecular and ionized hydrogen clouds, as e.g. for radio spectral lines in W51 emission nebulae, and in cooler stars as solar type ones for transitions involving higher principal quantum numbers. Present abundance analyses for early-type stars show that 10% - 20% of A and B stars have abundance anomalies, including anomalies in isotopic composition. The abundance anomalies in these stars, called CP stars, could be caused by diffusion occurring in the presence of selective radiative acceleration. The chemical species that absorb more of the outgoing photons are dragged by the photons to the stellar surface. Advanced calculation of the Stark broadening parameters using strong-coupling quantum-mechanical method are so complicated that only limited number of data for spectral lines originating from low laying transitions can be calculated in an adequate way. On the other hand, semiclassical method needs a set of large number of atomic data, energy levels and oscillator strengths. This method is not applicable in adequate way to the Stark broadening calculation of Zr II, Zr III and Cd III because there is no sufficient number of reliable atomic data. Here we use the modified semiempirical approach (MSE) which include explicitly only levels with δ n = 0 and l'if=lif +/- 1, where n is the principal quantum number, l is the orbital quantum number and i and f denote initial and final level, respectively. Levels with δ n ≠ 0 are lumped together and approximately estimated, so that for Stark broadening parameter calculation we need less atomic data then in the semiclassical method. The accuracy of the MSE calculations for spectral line widths is around +/- 50%. We present the computed electron-impact broadening parameters, Stark widths and shifts, for 30 multiplets of Zr III

  13. Plasma motions and non-thermal line broadening in flaring twisted coronal loops

    NASA Astrophysics Data System (ADS)

    Gordovskyy, M.; Kontar, E. P.; Browning, P. K.

    2016-05-01

    Context. Observation of coronal extreme ultra-violet (EUV) spectral lines sensitive to different temperatures offers an opportunity to evaluate the thermal structure and flows in flaring atmospheres. This, in turn, can be used to estimate the partitioning between the thermal and kinetic energies released in flares. Aims: Our aim is to forward-model large-scale (50-10 000 km) velocity distributions to interpret non-thermal broadening of different spectral EUV lines observed in flares. The developed models allow us to understand the origin of the observed spectral line shifts and broadening, and link these features to particular physical phenomena in flaring atmospheres. Methods: We use ideal magnetohydrodynamics (MHD) to derive unstable twisted magnetic fluxtube configurations in a gravitationally stratified atmosphere. The evolution of these twisted fluxtubes is followed using resistive MHD with anomalous resistivity depending on the local density and temperature. The model also takes thermal conduction and radiative losses in the continuum into account. The model allows us to evaluate average velocities and velocity dispersions, which would be interpreted as non-thermal velocities in observations, at different temperatures for different parts of the models. Results: Our models show qualitative and quantitative agreement with observations. Thus, the line-of-sight (LOS) velocity dispersions demonstrate substantial correlation with the temperature, increasing from about 20-30 km s-1 around 1 MK to about 200-400 km s-1 near 10-20 MK. The average LOS velocities also correlate with velocity dispersions, although they demonstrate a very strong scattering compared to the observations. We also note that near footpoints the velocity dispersions across the magnetic field are systematically lower than those along the field. We conclude that the correlation between the flow velocities, velocity dispersions, and temperatures are likely to indicate that the same heating

  14. Citizen Science: Broadening Access and Engagement Through Community Partnerships, Aerospace Education and Water Quality Research

    NASA Astrophysics Data System (ADS)

    Johnson, M. A.

    2016-12-01

    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

  15. A SYSTEMATIC SURVEY FOR BROADENED CO EMISSION TOWARD GALACTIC SUPERNOVA REMNANTS

    SciTech Connect

    Kilpatrick, Charles D.; Bieging, John H.; Rieke, George H.

    2016-01-01

    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.

  16. - and Air-Broadened Line Shape Parameters of 12CH_4 : 4500-4620 CM-1

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda; Crawford, Timothy J.; Smith, Mary Ann H.; Mantz, Arlan; Predoi-Cross, Adriana

    2014-06-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self- and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependences for methane absorption lines in the 2.2 μm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS. The 13 spectra used in the analysis consisted of seven pure 12CH_4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique. The results will be compared to existing values reported in the literature. K. Sung, A. W. Mantz, L. R. Brown, et al., J. Mol. Spectrosc., 162 (2010) 124-134. 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 was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  17. Broadening of analyte streams due to a transverse pressure gradient in free-flow isoelectric focusing.

    PubMed

    Dutta, Debashis

    2017-02-10

    Pressure-driven cross-flows can arise in free-flow isoelectric focusing systems (FFIEF) due to a non-uniform electroosmotic flow velocity along the channel width induced by the pH gradient in this direction. In addition, variations in the channel cross-section as well as unwanted differences in hydrostatic heads at the buffer/sample inlet ports can also lead to such pressure-gradients which besides altering the equilibrium position of the sample zones have a tendency to substantially broaden their widths deteriorating the separations. In this situation, a thorough assessment of stream broadening due to transverse pressure-gradients in FFIEF devices is necessary in order to establish accurate design rules for the assay. The present article describes a mathematical framework to estimate the noted zone dispersion in FFIEF separations based on the method-of-moments approach under laminar flow conditions. A closed-form expression has been derived for the spatial variance of the analyte streams at their equilibrium positions as a function of the various operating parameters governing the assay performance. This expression predicts the normalized stream variance under the chosen conditions to be determined by two dimensionless Péclet numbers evaluated based on the transverse pressure-driven and electrophoretic solute velocities in the separation chamber, respectively. Moreover, the analysis shows that while the stream width can be expected to increase with an increase in the value of the first Péclet number, the opposite trend will be followed with respect to the latter. The noted results have been validated using Monte Carlo simulations that also establish a time/length scale over which the predicted equilibrium stream width is attained in the system.

  18. Refinement of the semiclassical theory of the Stark broadening of hydrogen spectral lines in plasmas

    NASA Astrophysics Data System (ADS)

    Oks, Eugene

    2015-02-01

    Stark broadening (SB) of hydrogen, deuterium, and tritium lines (H-lines) is an important diagnostic tool for many applications. The most "user-friendly" are semiclassical theories of the SB of H-lines: their results can be expressed analytically in a relatively simple form for any H-line. The simplest semiclassical theory is the so-called Conventional Theory (CT), which is frequently referred to as Griem's theory. While by now there are several significantly more advanced semiclassical "non-CT" theories of the SB, Griem's CT is still used by a number of groups performing laboratory experiments or astrophysical observations for the comparison with their experimental or observational results. In the present study we engage unexplored capabilities of the CT for creating analytically a more accurate CT. First, we take into account that the perturbing electrons actually do not move as free particles: rather they move in a dipole potential V=·r/r3, where r is the radius-vector of the perturbing electrons and is the mean value of the radius vector of the atomic electron. Second, Griem's definition of the so-called Weisskopf radius was not quite accurate. Third, in his book of year 1974, Griem suggested changing so-called strong collision constant without changing the Weisskopf radius, while in reality the choices of the Weisskopf radius and of the strong collision constant are interrelated. We show that the above refinements of the CT increase the electron broadening - especially for warm dense plasmas emitting H-lines. By comparison with benchmark experiments concerning the Hα line we demonstrate that the effect of the ion dynamics (neglected in any CT) might be slightly smaller than previously thought, while the effect of the acceleration of perturbing electrons by the ion field in the vicinity of the radiating atom (neglected in any CT) might be greater than previously thought.

  19. Broadening Participation of Women and Underrepresented Minorities in STEM through a Hybrid Online Transfer Program.

    PubMed

    Drew, Jennifer C; Galindo-Gonzalez, Sebastian; Ardissone, Alexandria N; Triplett, Eric W

    2016-01-01

    The Microbiology and Cell Science (MCS) Department at the University of Florida (UF) developed a new model of a 2 + 2 program that uses a hybrid online approach to bring its science, technology, engineering, and mathematics (STEM) curriculum to students. In this paradigm, 2-year graduates transfer as online students into the Distance Education in MCS (DE MCS) bachelor of science program. The program has broadened access to STEM with a steadily increasing enrollment that does not draw students away from existing on-campus programs. Notably, half of the DE MCS students are from underrepresented minority (URM) backgrounds and two-thirds are women, which represents a greater level of diversity than the corresponding on-campus cohort and the entire university. Additionally, the DE MCS cohort has comparable retention and academic performance compared with the on-campus transfer cohort. Of those who have earned a BS through the DE MCS program, 71% are women and 61% are URM. Overall, these data demonstrate that the hybrid online approach is successful in increasing diversity and provides another viable route in the myriad of STEM pathways. As the first of its kind in a STEM field, the DE MCS program serves as a model for programs seeking to broaden their reach. © 2016 J. C. Drew et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  20. Homogeneous and inhomogeneous spectrum broadening in Nd3+-doped mixed vanadate crystals

    NASA Astrophysics Data System (ADS)

    Zhao, Yongguang; Yu, Haohai; Wang, Zhengping; Zhang, Huaijin; Xu, Xinguang; Wang, Jiyang

    2017-09-01

    Homogeneous and inhomogeneous spectrum broadening in Nd:LuxGd1-xVO4 series crystals were directly measured for the first time, and compared with that in the Nd:LuxY1-xVO4 and Nd:GdxY1-xVO4 crystals. Spectroscopic properties including fluorescence lifetime, spectral line width, emission peak, and stimulated emission cross section had obvious changes with the temperature increased from 77 K to 300 K, owing to the thermal phonon vibration. Compared to the pure vanadate crystals, we found these changes were more sensitive to temperature in the case of mixed crystals, in which cations (Lu, Y, and Gd) are random replaced by each other at the same lattice site. At 77 K, the thermal phonon vibration effect can be ignored and the inhomogeneous spectrum broadening that caused by disordered structure in all samplers can be calculated with the line-width of pure vanadate crystals as reference point, the corresponding values (ΔΓ(T)‧) were 2.2 nm-3.8 nm in 4F3/2 → 4I11/2 transition and 1.7 nm-2.8 nm in 4F3/2 → 4I13/2 transition. Compared to Nd:LuxY1-xVO4 and Nd:GdxY1-xVO4 series mixed crystals, the change in spectral line width with x is most obvious in the case of Nd:LuxGd1-xVO4 series crystals, which may be attributed to the larger ionic radius difference between Gd and Lu (RLu < RY < RGd).