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Far-infrared self-broadening in methylcyanide - Absorber-perturber resonance

NASA Technical Reports Server (NTRS)

Buffa, G.; Tarrini, O.; De Natale, P.; Inguscio, M.; Pavone, F. S.; Prevedelli, M.; Evenson, K. M.; Zink, L. R.; Schwaab, G. W.

1992-01-01

Using tunable far-infrared spectrometers with high-frequency stability and accuracy, the self-pressure broadening and shift of CH3CN are measured. Evidence of absorber-perturber resonance effects on the collisional line shape are obtained. This tests the theoretical model and its possible improvements and also allows predictions of broadening and shift for a large class of molecules. Moreover, the resonance effect produces a theoretical temperature dependence of self-broadening that is different from what is commonly assumed.

Contaminant-State Broadening Mechanism in a Driven Dissipative Rydberg System

NASA Astrophysics Data System (ADS)

Porto, J. V.

2017-04-01

The strong interactions in Rydberg atoms make them an ideal system for the study of correlated many-body physics, both in the presence and absence of dissipation. Using such highly excited atomic states requires addressing challenges posed by the dense spectrum of Rydberg levels, the detrimental effects of spontaneous emission, and strong interactions. A full understanding of the scope and limitations of many Rydberg-based proposals requires simultaneously including these effects, which typically cannot be described by a mean-field treatment due to correlations in the quantum coherent and dissipative processes. We study a driven, dissipative system of Rydberg atoms in a 3D optical lattice, and observe substantial deviation from single-particle excitation rates, both on and off resonance. The observed broadened spectra cannot be explained by van der Waals interactions or a mean-field treatment of the system. Based on the magnitude of the broadening and the scaling with density and two-photon Rabi frequency, we attribute these effects to unavoidable blackbody-induced transitions to nearby Rydberg states of opposite parity, which have large, resonant dipole-dipole interactions with the state of interest. Even at low densities of Rydberg atoms, uncontrolled production of atoms in other states significantly modifies the energy levels of the remaining atoms. These off-diagonal exchange interactions result in complex many-body states of the system and have implications for off-resonant Rydberg dressing proposals. This work was partially supported by the ARL-CDQI program.

Broadening Leaders? Culture Change as the Cure

DTIC Science & Technology

2012-04-05

system. The muddy boots culture results from how the Army defines career success – defined by selection for battalion and brigade command. By looking at...commanders reinforce the perception – repeated tactical assignments in lieu of risking broadening assignments is the path to career success that...boots culture actually discourages the pursuit of broadening assignments – the ―narrow definition or path of career success for Army officers

Statistical Fine Structure in Inhomogeneously Broadened Absorption Lines in Solids.

DTIC Science & Technology

1987-12-22

the inhomogeneously broadened zero-phonon SijSo (0-0) absorption of pentacene molecules in crystals of p-terphenyl at liquid helium temperatures. SFS...structure (SFS) in the inhomogeneously broadened zero-phonon S, +- So (0-0) absorption of pentacene molecules in crystals of p-terphenyl at liquid helium...tile large multiplicity of local environments. Inhomogeneously broadened absorption lines are usually treated as smooth, Gaussian profiles. In recent

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

Immunity of intersubband polaritons to inhomogeneous broadening

NASA Astrophysics Data System (ADS)

Manceau, J.-M.; Biasiol, G.; Tran, N. L.; Carusotto, I.; Colombelli, R.

2017-12-01

We demonstrate that intersubband (ISB) polaritons are robust to inhomogeneous effects originating from the presence of multiple quantum wells (MQWs). In a series of samples that exhibit mid-infrared ISB absorption transitions with broadenings varying by a factor of 5 (from 4 to 20 meV), we observed polariton linewidths always lying in the 4 to 7 meV range only. We experimentally verified the dominantly inhomogeneous origin of the broadening of the ISB transition, and that the linewidth reduction effect of the polariton modes persists up to room-temperature. This immunity to inhomogeneous broadening is a direct consequence of the coupling of the large number of ISB oscillators to a single photonic mode. It is a precious tool to gauge the natural linewidth of the ISB plasmon that is otherwise masked in such MQWs system, and is also beneficial in view of perspective applications such as intersubband polariton lasers.

EIT Noise Resonance Power Broadening: a probe for coherence dynamics

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; O'Leary, Shannon; Snider, Charles

2012-06-01

EIT noise correlation spectroscopy holds promise as a simple, robust method for performing high resolution spectroscopy used in devices as diverse as magnetometers and clocks. One useful feature of these noise correlation resonances is that they do not power broaden with the EIT window. We report on measurements of the eventual power broadening (at higher optical powers) of these resonances and a simple, quantitative theoretical model that relates the observed power broadening slope with processes such as two-photon detuning gradients and coherence diffusion. These processes reduce the ground state coherence relative to that of a homogeneous system, and thus the power broadening slope of the EIT noise correlation resonance may be a simple, useful probe for coherence dynamics.

Pressure broadening of the ((dt. mu. )dee)* formation resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, J.S.; Leon, M.; Padial, N.T.

1988-12-27

The treatment of ((dt..mu..)dee)* formation at high densities as a pressure broadening process is discussed. Cross sections for collisions of the complex (dt..mu..)dee, and of the D/sub 2/ molecule from which it is formed, with the bath molecules have been accurately calculated. These cross sections are used to calculate the collisional width in three variations of the impact approximation that have been proposed for this problem. In general, the quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. A preliminary rough treatment is presented to illustrate the quasistatic approximation.

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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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

EIT intensity noise spectroscopy power-broadening and level structure

NASA Astrophysics Data System (ADS)

Snider, Charles; Crescimanno, Michael; Oleary, Shannon

2011-05-01

One particularly interesting (and potentially technologically useful) characteristic of EIT coherence as viewed through intensity noise spectroscopy is its power-broadening resistant features. We detail a connection between the power broadening behavior and the underlying level structure by solving a more realistic quantum optics scenario modeled on recent experiments.

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.

Causes of power broadening in EIT intensity noise spectroscopy

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Snider, Charles; O'Leary, Shannon

2011-05-01

EIT noise spectroscopy is a potentially promising way to simplify magnetometer design. One technically fortuitous characteristic of this intensity noise spectroscopy is the non-power broadening behaviour. We describe quantum optics theory applied to more realistic models of EIT systems that explain the existence and range of this power broadening-free regime.

Homogenization of Doppler broadening in spin-noise spectroscopy

NASA Astrophysics Data System (ADS)

Petrov, M. Yu.; Ryzhov, I. I.; Smirnov, D. S.; Belyaev, L. Yu.; Potekhin, R. A.; Glazov, M. M.; Kulyasov, V. N.; Kozlov, G. G.; Aleksandrov, E. B.; Zapasskii, V. S.

2018-03-01

The spin-noise spectroscopy, being a nonperturbative linear optics tool, is still reputed to reveal a number of capabilities specific to nonlinear optics techniques. The effect of the Doppler broadening homogenization discovered in this work essentially widens these unique properties of spin-noise spectroscopy. We investigate spin noise of a classical system—cesium atoms vapor with admixture of buffer gas—by measuring the spin-induced Faraday rotation fluctuations in the region of D 2 line. The line, under our experimental conditions, is strongly inhomogeneously broadened due to the Doppler effect. Despite that, optical spectrum of the spin-noise power has the shape typical for the homogeneously broadened line with a dip at the line center. This fact is in stark contrast with the results of previous studies of inhomogeneous quantum dot ensembles and Doppler broadened atomic systems. In addition, the two-color spin-noise measurements have shown, in a highly spectacular way, that fluctuations of the Faraday rotation within the line are either correlated or anticorrelated depending on whether the two wavelengths lie on the same side or on different sides of the resonance. The experimental data are interpreted in the frame of the developed theoretical model which takes into account both kinetics and spin dynamics of Cs atoms. It is shown that the unexpected behavior of the Faraday rotation noise spectra and effective homogenization of the optical transition in the spin-noise measurements are related to smallness of the momentum relaxation time of the atoms as compared with their spin-relaxation time. Our findings demonstrate abilities of spin-noise spectroscopy for studying dynamic properties of inhomogeneously broadened ensembles of randomly moving spins.

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.

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.

D2O self-broadening study in 2.5 μ

NASA Astrophysics Data System (ADS)

Lavrentieva, N.; Lugovskoi, A.; Sinitsa, L.; Sherbakov, A.; Svetlichny, O.

2014-11-01

The absorption spectra of the D2O monomer in 3600…4200 cm-1 were recorded using Fourier Transform spectrometer FS-125M at room temperature and pressure of 15 and 33 mbar with spectral resolution of 0.03 cm-1 using 2.5 cm long absorption cell. Strong unblended D2O lines lying on the wing of the H2O stretching band were used to determine the line broadening parameters. They were determined from the line profile by Program VxpProfile. The differences between fitted line profiles and experimental ones do not exceed 2%. Registered D2O lines belong to (011) - (000) and (110) - (000) bands of the second triad. Self-broadening coefficients vary from 0.27 cm-1/atm to 0.445 cm-1/atm and they exceed 3 times the D2O-N2 line broadening coefficients in the v3. Calculations of self-broadening coefficients of the D2O lines were performed using semiempirical method based on the impact theory of broadening and included the correction factors. The calculated results well agree with experimental data.

Seeing the big picture: Broadening attention relieves sadness and depressed mood.

PubMed

Gu, Li; Yang, Xueling; Li, Liman Man Wai; Zhou, Xinyue; Gao, Ding-Guo

2017-08-01

We examined whether the broadened attentional scope would affect people's sad or depressed mood with two experiments, enlightened by the meaning of "seeing the big picture" and the broaden-and-build model. Experiment 1 (n = 164) is a laboratory-based experiment, in which we manipulated the attentional scope by showing participants zoomed-out or zoomed-in scenes. In Experiment 2 (n = 44), we studied how depressed mood and positive and negative emotions were affected when participants watched distant versus proximal scenes for eight weeks in real life. Healthy participants in Experiment 1, who were induced to feel sad, could return to the baseline mood after having the broadened attention task but not after having the narrowed attention task, which indicated that immediate attention broadening manipulation could function as antidotes for the lingering effects of induced negative emotions. Participants with depressed mood in Experiment 2 showed reduced depressed mood, increased positive affect, and decreased negative affect after receiving attention broadening training compared to those receiving attention narrowing training. Our findings suggest a robust role of broadened attentional scope in relieving negative emotions and even mildly depressed mood in the long run. © 2017 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Single-photon superradiant beating from a Doppler-broadened ladder-type atomic ensemble

NASA Astrophysics Data System (ADS)

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

2017-12-01

We report on heralded-single-photon superradiant beating in the spontaneous four-wave mixing process of Doppler-broadened ladder-type 87Rb atoms. When Doppler-broadened atoms contribute to two-photon coherence, the detection probability amplitudes of the heralded single photons are coherently superposed despite inhomogeneous broadened atomic media. Single-photon superradiant beating is observed, which constitutes evidence for the coherent superposition of two-photon amplitudes from different velocity classes in the Doppler-broadened atomic ensemble. We present a theoretical model in which the single-photon superradiant beating originates from the interference between wavelength-separated two-photon amplitudes via the reabsorption filtering effect.

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.

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

Hydrogen Balmer Line Broadening in Solar and Stellar Flares

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kowalski, Adam F.; Allred, Joel C.; Uitenbroek, Han

2017-03-10

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 Voigtmore » 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.« less

Hydrogen Balmer Line Broadening in Solar and Stellar Flares

NASA Technical Reports Server (NTRS)

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

2017-01-01

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 ultra relativistic electron beam with reasonable filling factors: approximately 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.

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.

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.

Effects of positive mood on attention broadening for self-related information.

PubMed

Grol, Maud; Koster, Ernst H W; Bruyneel, Lynn; De Raedt, Rudi

2014-07-01

Studies on cognitive effects of positive emotions have associated positive emotions to broadened attention. Given the widely investigated relationship between self-focused attention and mood, it is important to investigate the effect of positive mood on visuospatial attention for self-related information. We used a performance-based measure to assess fluctuations in attentional broadening from self-related contrasted to not-self-related information. In Experiment 1, we checked that the self-related versus not-self-related stimuli did not evoke differential attention effects in general. In Experiment 2, we manipulated mood and found that an increase in positive mood was associated with a relative broadening of attention for self-related information. These results suggest that the meaning of the target of attention provides an interesting dimension for further investigation into the relation between positive emotions and attentional broadening.

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.

Self-phase-modulation induced spectral broadening in silicon waveguides

NASA Astrophysics Data System (ADS)

Boyraz, Ozdal; Indukuri, Tejaswi; Jalali, Bahram

2004-03-01

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

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.

Broadening and collisional interference of lines in the IR spectra of ammonia. Theory

NASA Astrophysics Data System (ADS)

Cherkasov, M. R.

2016-06-01

The general theory of relaxation spectral shape parameters in the impact approximation (M. R. Cherkasov, J. Quant. Spectrosc. Radiat. Transfer 141, 73 (2014)) is adapted to the case of line broadening of infrared spectra of ammonia. Specific features of line broadening of parallel and perpendicular bands are discussed. It is shown that in both cases the spectrum consists of independently broadened singlets and doublets; however, the components of doublets can be affected by collisional interference. The paper is the first part of a cycle of studies devoted to the problems of spectral line broadening of ammonia.

Observation of Doppler broadening in beta-delayed proton-gamma decay

NASA Astrophysics Data System (ADS)

Schwartz, Sarah

The Doppler broadening of gamma-ray peaks due to nuclear recoil from beta-delayed nucleon emission can be used to measure the energies of the nucleons. The purpose of this Thesis is to test and apply this Doppler broadening method using gamma-ray peaks from the 26P(betapgamma) 25Al decay sequence. A fast beam of 26P was implanted into a planar Ge detector, which was used as a 26P beta-decay trigger. The SeGA array of high-purity Ge detectors was used to detect gamma rays from the 26P(betapgamma)25Al decay sequence. Radiative Doppler broadening in beta-delayed proton-gamma decay was observed for the first time. The Doppler broadening analysis method was verified using the 1613 keV gamma-ray line for which the proton energies were previously known. The 1776 keV gamma ray de-exciting the 2720 keV 25Al level was observed in 26P(betapgamma) 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.) +/- 0.7 (syst.) MeV for the proton-emitting level. 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.

Approaches to characterise chromatographic column performance based on global parameters accounting for peak broadening and skewness.

PubMed

Baeza-Baeza, J J; Pous-Torres, S; Torres-Lapasió, J R; García-Alvarez-Coque, M C

2010-04-02

Peak broadening and skewness are fundamental parameters in chromatography, since they affect the resolution capability of a chromatographic column. A common practice to characterise chromatographic columns is to estimate the efficiency and asymmetry factor for the peaks of one or more solutes eluted at selected experimental conditions. This has the drawback that the extra-column contributions to the peak variance and skewness make the peak shape parameters depend on the retention time. We propose and discuss here the use of several approaches that allow the estimation of global parameters (non-dependent on the retention time) to describe the column performance. The global parameters arise from different linear relationships that can be established between the peak variance, standard deviation, or half-widths with the retention time. Some of them describe exclusively the column contribution to the peak broadening, whereas others consider the extra-column effects also. The estimation of peak skewness was also possible for the approaches based on the half-widths. The proposed approaches were applied to the characterisation of different columns (Spherisorb, Zorbax SB, Zorbax Eclipse, Kromasil, Chromolith, X-Terra and Inertsil), using the chromatographic data obtained for several diuretics and basic drugs (beta-blockers). Copyright (c) 2010 Elsevier B.V. All rights reserved.

Theory and Simulation of Exoplanetary Atmospheric Haze: Giant Spectral Line Broadening

NASA Astrophysics Data System (ADS)

Sadeghpour, Hossein; Felfeli, Zineb; Kharchenko, Vasili; Babb, James; Vrinceanu, Daniel

2018-01-01

Prominent spectral features in observed transmission spectra of exoplanets are obscured. Atmospheric haze is the leading candidate for the flattening of spectral transmission of expolanetray occultation, but also for solar system planets, Earth and cometary atmospheres. Such spectra which carry information about how the planetary atmospheres become opaque to stellar light in transit, show broad absorption where strong absorption lines from sodium or potassium and water are predicted to exist. In this work, we develop a detailed atomistic theoretical model, taking into account interaction between an atomic or molecular radiator with dust and haze particulates. Our model considers a realistic structure of haze particulates from small seed particles up to sub-micron irregularly shaped aggregates. This theory of interaction between haze and radiator particles allows to consider nearly all realistic structure, size and chemical composition of haze particulates. The computed shift and broadening of emission spectra will include both quasi-static (mean field) and collisional (pressure) shift and broadening. Our spectral calculations will be verified with available laboratory experimental data on spectra of alkali atoms in liquid droplet, solid ice, dust and dense gaseous environments. The simplicity, elegance and generality of the proposed model makes it amenable to a broad community of users in astrophysics and chemistry. The verified models can be used for analysis of emission and absorption spectra of alkali atoms from exoplanets, solar system planets, satellites and comets.

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

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.

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

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 .

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

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.

Interface contributions to peak broadening in CE-ESI-MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Udseth, H.R.; Barinaga, C.J.; Smith, R.D.

1991-06-01

The applications of capillary electrophoresis (CE) are expanding, and a number of commercial CE instruments are now available. Combining CE with mass spectroscopy (MS), first done with an electrospray ionization (ESI) interface, yields additional advantages. Other interfaces have been proposed, but CE-ESI-MS offers better sensitivity, reduced background, applicability to higher molecular weight (MW) compounds and a better interface design. Our aim has been to exploit the advantages of automated CE coupled to MS for separation of biological materials. Details of our instrument design are provided. Samples used for these studies were a mixture of myoglobin proteins (MW {approximately}17 kilodaltons) andmore » a tryptic digest of tuna cytochrome c. The results show the ESI-MS interface does not broaden bands, and ion dissociation in the mass spectrometer permits the unambiguous identification of fragments in cases where mass alone is insufficient. 2 refs., 2 figs. (MHB)« less

Measurement of Spectral Broadening in PTS-Polydiacetylene

NASA Astrophysics Data System (ADS)

Bhowmik, Achintya; Thakur, Mrinal

1998-03-01

PTS-polydiacetylene has significant potential for future applications in ultrafast all-optical switches and logic gates.(R. Quintero-Torres and M. Thakur, Appl. Phys. Lett., 66, 1310 (1995).) In this work, we have made detailed measurements of the instantaneous spectral line broadening in a 500 μm thick PTS single-crystal as a function of intensity and wavelength. A mode-locked Ti-Sapphire laser with 2 ps pulse-width at 82 MHz repetition rate, and a Nd:YAG laser with 60 ps pulse-width at 10 Hz repetition rate were used for measurements at 720-840 nm and 1064 nm wavelength respectively. The spectral bandwidth of the beam was recorded before and after passing through the PTS single-crystal by a high-resolution spectrometer. The nonlinear refractive index (n_2) of PTS as a function of wavelength has been determined from the spectral broadening data.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.more » 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.« less

Bandwidth broadening of a graphene-based circular polarization converter by phase compensation.

PubMed

Gao, Xi; Yang, Wanli; Cao, Weiping; Chen, Ming; Jiang, Yannan; Yu, Xinhua; Li, Haiou

2017-10-02

We present a broadband tunable circular polarization converter composed of a single graphene sheet patterned with butterfly-shaped holes, a dielectric spacer, and a 7-layer graphene ground plane. It can convert a linearly polarized wave into a circularly polarized wave in reflection mode. The polarization converter can be dynamically tuned by varying the Fermi energy of the single graphene sheet. Furthermore, the 7-layer graphene acting as a ground plane can modulate the phase of its reflected wave by controlling the Femi energy, which provides constructive interference condition at the surface of the single graphene sheet in a broad bandwidth and therefore significantly broadens the tunable bandwidth of the proposed polarization converter.

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.

Digital nonlinearity compensation in high-capacity optical communication systems considering signal spectral broadening effect.

PubMed

Xu, Tianhua; Karanov, Boris; Shevchenko, Nikita A; Lavery, Domaniç; Liga, Gabriele; Killey, Robert I; Bayvel, Polina

2017-10-11

Nyquist-spaced transmission and digital signal processing have proved effective in maximising the spectral efficiency and reach of optical communication systems. In these systems, Kerr nonlinearity determines the performance limits, and leads to spectral broadening of the signals propagating in the fibre. Although digital nonlinearity compensation was validated to be promising for mitigating Kerr nonlinearities, the impact of spectral broadening on nonlinearity compensation has never been quantified. In this paper, the performance of multi-channel digital back-propagation (MC-DBP) for compensating fibre nonlinearities in Nyquist-spaced optical communication systems is investigated, when the effect of signal spectral broadening is considered. It is found that accounting for the spectral broadening effect is crucial for achieving the best performance of DBP in both single-channel and multi-channel communication systems, independent of modulation formats used. For multi-channel systems, the degradation of DBP performance due to neglecting the spectral broadening effect in the compensation is more significant for outer channels. Our work also quantified the minimum bandwidths of optical receivers and signal processing devices to ensure the optimal compensation of deterministic nonlinear distortions.

Studies of solar flares: Homology and X-ray line broadening

NASA Astrophysics Data System (ADS)

Ranns, Neale David Raymond

This thesis starts with an introduction to the solar atmosphere and the physics that governs its behaviour. The formation processes of spectral lines are presented followed by an explanation of employed plasma diagnostic techniques and line broadening mechanisms. The current understanding on some principle concepts of flare physics are reviewed and the topics of flare homology and non-thermal line broadening are introduced. The many solar satellites and instrumentation that were utilised during this thesis are described. Analysis techniques for some instruments are also presented. A series of solar flares that conform to the literature definition for homologous flares are examined. The apparent homology is shown to be caused by emerging flux rather than continual stressing of a single, or group of, magnetic structure's. The implications for flare homology are discussed. The analysis of a solar flare with a rise and peak in the observed non-thermal X-ray line broadening (Vnt) is then performed. The location of the hot plasma within the flare area is determined and consequently the source of Vnt is located to be within and above the flare loops. The flare footpoints are therefore discarded as a possible source location. Viable source locations are discussed with a view to determining the dominant mechanism for the generation of line broadening. The timing relationships between the hard X-ray (HXR) flux and Vnt in many solar flares are then examined. I show that there is a causal relationship between these two parameters and that the HXR rise time is related to the time delay between the maxima of HXR flux and Vnt. The temporal evolution of Vnt is shown to be dependent upon the shape of the HXR burst. The implications of these results are discussed in terms of determining the line broadening mechanism and the limitations of the data. A summary of the results in this thesis is then presented together with suggestions for future research.

Hydrogen and Nitrogen Broadened Ethane and Propane Absorption Cross Sections

NASA Astrophysics Data System (ADS)

Hargreaves, Robert J.; Appadoo, Dominique; Billinghurst, Brant E.; Bernath, Peter F.

2015-06-01

High-resolution infrared absorption cross sections are presented for the ν9 band of ethane (C2H6) at 823 cm-1. These cross sections make use of spectra recorded at the Australian Synchrotron using a Fourier transform infrared spectrometer with maximum resolution of 0.00096 cm-1. The spectra have been recorded at 150, 120 and 90 K for hydrogen and nitrogen broadened C2H6. They cover appropriate temperatures, pressures and broadening gases associated with the atmospheres of the Outer Planets and Titan, and will improve atmospheric retrievals. The THz/Far-IR beamline at the Australian Synchrotron is unique in combining a high-resolution Fourier transform spectrometer with an 'enclosive flow cooling' (EFC) cell designed to study molecules at low temperatures. The EFC cell is advantageous at temperatures for which the vapor pressure is very low, such as C2H6 at 90 K. Hydrogen broadened absorption cross sections of propane between 700 and 1200 cm-1 will also be presented based on spectra obtained at the Canadian Light Source.

Broadening the optical bandwidth of quantum cascade lasers using RF noise current perturbations.

PubMed

Pinto, Tomás H P; Kirkbride, James M R; Ritchie, Grant A D

2018-04-15

We report on the broadening of the optical bandwidth of a distributed feedback quantum cascade laser (QCL) caused by the application of radio frequency (RF) noise to the injection current. The broadening is quantified both via Lamb-dip spectroscopy and the frequency noise power spectral density (PSD). The linewidth of the unperturbed QCL (emitting at ∼5.3  μm) determined by Lamb-dip spectroscopy is 680±170  kHz, and is in reasonable agreement with the linewidth of 460±40  kHz estimated by integrating the PSD measured under the same laser operating conditions. Measurements with both techniques reveal that by mixing the driving current with broadband RF noise the laser lineshape was reproducibly broadened up to ca 6 MHz with an increasing Gaussian contribution. The effects of linewidth broadening are then demonstrated in the two-color coherent transient spectra of nitric oxide.

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.

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

PubMed

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

2016-06-08

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.

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

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.

Low power generation of equalized broadband CW supercontinua using a novel technique incorporating modulation instability of line broadened pump

NASA Astrophysics Data System (ADS)

Prakash, Roopa; Choudhury, Vishal; Arun, S.; Supradeepa, V. R.

2018-02-01

Continuous-wave(CW) supercontinuum sources find applications in various domains such as imaging, spectroscopy, test and measurement. They are generated by pumping an optical fiber with a CW laser in the anomalous-dispersion region close to its zero-dispersion wavelength. Modulation instability(MI) sidebands are created, and further broadened and equalized by additional nonlinear processes generating the supercontinuum. This necessitates high optical powers and at lower powers, only MI sidebands can be seen without the formation of the supercontinuum. Obtaining a supercontinuum at low, easily manageable optical powers is attractive for many applications, but current techniques cannot achieve this. In this work, we propose a new mechanism for low power supercontinuum generation utilizing the modified MI gain spectrum for a line-broadened, decorrelated pump. A novel two-stage generation mechanism is demonstrated, where the first stage constituting standard telecom fiber slightly broadens the input pump linewidth. However, this process in the presence of dispersion, acts to de-correlate the different spectral components of the pump signal. When this is sent through highly nonlinear fiber near its zero-dispersion wavelength, the shape of the MI gain spectrum is modified, and this process naturally results in the generation of a broadband, equalized supercontinuum source at much lower powers than possible using conventional single stage spectral broadening. Here, we demonstrate a 0.5W supercontinuum source pumped using a 4W Erbium-Ytterbium co-doped fiber laser with a bandwidth spanning from 1300nm to 2000nm. We also demonstrate an interesting behaviour of this technique of relative insensitivity to the pump wavelength vis-a-vis zero-dispersion wavelength of the fiber.

PULSE BROADENING MEASUREMENTS FROM THE GALACTIC CENTER PULSAR J1745-2900

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spitler, L. G.; Lee, K. J.; Eatough, R. P.

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 GHzmore » 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.« less

Broadening and Shifting of Atomic Strontium and Diatomic Bismuth Spectral Lines

DTIC Science & Technology

2003-05-01

Upper Energy State, Ek kA q kA q jA jA Figure 2-4. Transition between the lower and upper energy states of an atom or molecule affected by quenching...broadened by both lifetime effects and quenching. This profile has a F HM given by Equation 2-16. W q q jA kA qq vNA (2-17) where N is the...December 1998 (AD-A361408)(9921302). 42. Predoi-Cross, Adriana , J. P. Bouanich, D. C. Benner, A. D. May, and J. R. Drummond. “Broadening, Shifting

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2015-10-28

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. Thus we then extract the nonradiative recombination current associated with the quantum-dot active regionmore » from a comparison of measured and calculated gain versus current relations.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, Weng W., E-mail: wwchow@sandia.gov; Liu, Alan Y.; Gossard, Arthur C.

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 amore » comparison of measured and calculated gain versus current relations.« less

Windowed multipole for cross section Doppler broadening

NASA Astrophysics Data System (ADS)

Josey, C.; Ducru, P.; Forget, B.; Smith, K.

2016-02-01

This paper presents an in-depth analysis on the accuracy and performance of the windowed multipole Doppler broadening method. The basic theory behind cross section data is described, along with the basic multipole formalism followed by the approximations leading to windowed multipole method and the algorithm used to efficiently evaluate Doppler broadened cross sections. The method is tested by simulating the BEAVRS benchmark with a windowed multipole library composed of 70 nuclides. Accuracy of the method is demonstrated on a single assembly case where total neutron production rates and 238U capture rates compare within 0.1% to ACE format files at the same temperature. With regards to performance, clock cycle counts and cache misses were measured for single temperature ACE table lookup and for windowed multipole. The windowed multipole method was found to require 39.6% more clock cycles to evaluate, translating to a 7.9% performance loss overall. However, the algorithm has significantly better last-level cache performance, with 3 fewer misses per evaluation, or a 65% reduction in last-level misses. This is due to the small memory footprint of the windowed multipole method and better memory access pattern of the algorithm.

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.

[The application of Doppler broadening and Doppler shift to spectral analysis].

PubMed

Xu, Wei; Fang, Zi-shen

2002-08-01

The distinction between Doppler broadening and Doppler shift has analyzed, Doppler broadening locally results from the distribution of velocities of the emitting particles, the line width gives the information on temperature of emitting particles. Doppler shift results when the emitting particles have a bulk non random flow velocity in a particular direction, the drift of central wavelength gives the information on flow velocity of emitting particles, and the Doppler shift only drifts the profile of line without changing the width. The difference between Gaussian fitting and the distribution of chord-integral line shape have also been discussed. The distribution of H alpha spectral line shape has been derived from the surface of limiter in HT-6M Tokamak with optical spectroscope multichannel analysis (OSMA), the result by double Gaussian fitting shows that the line shape make up of two port, the emitting of reflect particles with higher energy and the release particle from the limiter surface. Ion temperature and recycling particle flow velocity have been obtained from Doppler broadening and Doppler shift.

A Solar-flux Line-broadening Analysis

NASA Astrophysics Data System (ADS)

Gray, David F.

2018-04-01

The Fourier technique of extracting rotation rates and macroturbulence-velocity dispersions from the shapes and broadening of stellar spectral lines is applied to the solar-flux spectrum. Lines with equivalent widths less than ∼0.055 Å are shown to have the advantage over stronger lines by allowing the residual transform to be followed to higher frequencies. The standard radial-tangential macroturbulence formulation fits the observations well and yields an equatorial velocity that is within a few percent of the correct rate.

Ab Initio Computation of Dynamical Properties: Pressure Broadening

NASA Astrophysics Data System (ADS)

Wiesenfeld, Laurent; Drouin, Brian

2014-06-01

Rotational spectroscopy of polar molecules is the main observational tool in many areas of astrophysics, for gases of low densities (n ˜ 102 - 108 cm-3). Spectral line shapes in astrophysical media are largely dominated by turbulence-induced Doppler effects and natural line broadening are negligible. However line broadening remains an important tool for denser gases, like planetary high atmospheres. Understanding the excitation schemes of polar molecules requires the knowledge of excitation transfer rate due to collisional excitation, between the polar molecule and the ambient gas, usually H2. Transport properties in ionized media also require a precise knowledge of momentum transfer rates by elastic collisions. In order to assess the theoretically computed cross section and energy/momentum transfer rates, direct absolute experiments are scarce. The best way is to measure not individual scattering events but rather the global effect of the buffer gas, thanks to the pressure broadening cross sections, whose magnitude can be measured without any scaling parameters. At low temperatures, both elastic and inelastic scattering amplitudes are tested. At higher temperature, depending on the interaction strength, only inelastic scattering cross section are shown to play a significant role 1 ,2. Thanks to the advances of computer capabilities, it has become practical to compute spectral line parameters fromab initio quantum chemistry. In particular, the theory of rotational line broadening is readily incorporated into scattering quantum dynamical theory, like close-coupling schemes. The only approximations used in the computation are the isolated collision/isolated line approximations. We compute the non-binding interaction potential with high precision quantum chemistry and fit the resulting ab initio points onto a suitable functional. We have recently computed several such systems, for molecules in H2 buffer gas: H2O,3 H2CO,4 HCO+ .5 Detailed computations taking into

The effect of broadened linewidth induced by dispersion on the performance of resonant optical gyroscope

NASA Astrophysics Data System (ADS)

Zhang, Hao; Li, Wenxiu; Han, Peng; Chang, Xiaoyang; Liu, Jiaming; Lin, Jian; Xue, Xia; Zhu, Fang; Yang, Yang; Liu, Xiaojing; Zhang, Xiaofu; Huang, Anping; Xiao, Zhisong; Fang, Jiancheng

2018-01-01

Anomalous dispersion enhancement physical mechanism for Sagnac effect is described by special relativity derivation, and three kinds of definitions of minimum detectable angular rate of resonance optical gyroscope (ROG) are compared and the relations among them are investigated. The effect of linewidth broadening induced by anomalous dispersion on the sensitivity of ROG is discussed in this paper. Material dispersion-broadened resonance linewidth deteriorates the performance of a passive ROG and dispersion enhancement effect, while the sensitivity of a structural dispersion ROG is enhanced by two orders of magnitude even considering the dispersion-broadened resonance linewidth.

Combinatorial Broadening Mechanism of O-H Stretching Bands in H-Bonded Molecular Clusters

NASA Astrophysics Data System (ADS)

Pitsevich, G. A.; Doroshenko, I. Yu.; Pogorelov, V. E.; Pettersson, L. G. M.; Sablinskas, V.; Sapeshko, V. V.; Balevicius, V.

2016-07-01

A new mechanism for combinatorial broadening of donor-OH stretching-vibration absorption bands in molecular clusters with H-bonds is proposed. It enables the experimentally observed increase of the O-H stretching-vibration bandwidth with increasing number of molecules in H-bonded clusters to be explained. Knowledge of the half-width of the OH stretching-vibration absorption band in the dimer and the number of H-bonds in the analyzed cluster is suffi cient in the zeroth-order approximation to estimate the O-H stretching-absorption bands in clusters containing several molecules. Good agreement between the calculated and published experimental half-widths of the OH stretching-vibration absorption bands in MeOH and PrOH clusters was obtained using this approach.

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.

Importance of Doppler broadening in Compton scatter imaging techniques

NASA Astrophysics Data System (ADS)

Rao, Donepudi V.; Takeda, Tohoru; Itai, Yuji; Seltzer, S. M.; Hubbell, John H.; Zeniya, Tsutomu; Akatsuka, Takao; Cesareo, Roberto; Brunetti, Antonio; Gigante, Giovanni E.

2001-12-01

Compton scattering is a potential tool for the determination of bone mineral content or tissue density for dose planning purposes, and requires knowledge of the energy distribution of the X-rays through biological materials of medical interest in the X-ray and (gamma) -ray region. The energy distribution is utilized in a number of ways in diagnostic radiology, for example, in determining primary photon spectra, electron densities in separate volumes, and in tomography and imaging. The choice of the X-ray energy is more related to X-ray absorption, where as that of the scattering angle is more related to geometry. The evaluation of all the contributions are mandatory in Compton profile measurements and is important in X-ray imaging systems in order to achieve good results. In view of this, Compton profile cross-sections for few biological materials are estimated at nineteen K(alpha) X-ray energies and 60 keV (Am-241) photons. Energy broadening, geometrical broadening from 1 to 180 degree(s), FWHM of J(Pz) and FWHM of Compton energy broadening has been evaluated at various incident photon energies. These values are estimated around the centroid of the Compton profile with an energy interval of 0.1 keV and 1.0 keV for 60 keV photons. The interaction cross sections for the above materials are estimated using fractions-by-weight of the constituent elements. Input data for these tables are purely theoretical.

Pressure broadening and pressure shift of diatomic iodine at 675 nm

NASA Astrophysics Data System (ADS)

Wolf, Erich N.

Doppler-limited, steady-state, linear absorption spectra of 127 I2 (diatomic iodine) near 675 nm were recorded with an internally-referenced wavelength modulation spectrometer, built around a free-running diode laser using phase-sensitive detection, and capable of exceeding the signal-to-noise limit imposed by the 12-bit data acquisition system. Observed I2 lines were accounted for by published spectroscopic constants. Pressure broadening and pressure shift coefficients were determined respectively from the line-widths and line-center shifts as a function of buffer gas pressure, which were determined from nonlinear regression analysis of observed line shapes against a Gaussian-Lorentzian convolution line shape model. This model included a linear superposition of the I2 hyperfine structure based on changes in the nuclear electric quadrupole coupling constant. Room temperature (292 K) values of these coefficients were determined for six unblended I 2 lines in the region 14,817.95 to 14,819.45 cm-1 for each of the following buffer gases: the atoms He, Ne, Ar, Kr, and Xe; and the molecules H2, D2, N2, CO2, N2O, air, and H2O. These coefficients were also determined at one additional temperature (388 K) for He and CO2, and at two additional temperatures (348 and 388 K) for Ar. Elastic collision cross-sections were determined for all pressure broadening coefficients in this region. Room temperature values of these coefficients were also determined for several low-J I2 lines in the region 14,946.17 to 14,850.29 cm-1 for Ar. A line shape model, obtained from a first-order perturbation solution of the time-dependent Schrodinger equation for randomly occurring interactions between a two-level system and a buffer gas treated as step-function potentials, reveals a relationship between the ratio of pressure broadening to pressure shift coefficients and a change in the wave function phase-factor, interpreted as reflecting the "cause and effect" of state-changing events in the

Self- and foreign-gas broadening of ethane lines determined from diode laser measurements at 12 microns

NASA Technical Reports Server (NTRS)

Blass, W. E.; Halsey, G. W.; Jennings, D. E.

1987-01-01

Self- and foreign-gas broadening of ethane lines have been measured in the nu9 band at 12 microns. A coefficient of 0.125 per cm atm was determined for self broadening. Foreign-gas broadening coefficients determined are (in per cm atm) 0.090 for N2, 0.069 for He, 0.068 for Ar, 0.108 for H2, and 0.096 for CH4. Results are given for a sample temperature of 296 K.

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%.

Measurements of pressure-broadening coefficients of NO and O3 using a computerized tunable diode laser spectrometer

NASA Technical Reports Server (NTRS)

Lundqvist, S.; Margolis, J.; Reid, J.

1982-01-01

Foreign-gas broadening coefficients have been measured for selected lines of ozone in the 9.2 micron region and for several R-branch lines of nitric oxide in the 5.4 micron region using a computerized tunable diode laser spectrometer. The data analysis showed the importance of fitting a Lorentzian line shape out to several times the halfwidth to obtain a correct value of the broadening coefficient. The measured broadening coefficients of nitric oxide were in good agreement with those obtained by Abels and Shaw (1966). The results of the analysis of eleven lines in the v-1 band and five lines in the v-3 band of ozone show a transition-dependent broadening coefficient. The average value of the foreign-gas broadening ceofficients for the measured v-1 and v-3 lines are 0.075 and 0.073 per cm per atm, respectively.

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.

The Frequency Evolution of Interstellar Pulse Broadening from Radio Pulsars

NASA Astrophysics Data System (ADS)

Löhmer, O.; Mitra, D.; Gupta, Y.; Kramer, M.; Ahuja, A.

2004-10-01

Using radio pulsars as probes of the interstellar medium (ISM) we study the frequency evolution of interstellar scattering. The frequency dependence of scatter broadening times, τsc, for most of the pulsars with low and intermediate dispersion measures (DM ≲ 400 pc cm-3) is consistent with the Kolmogorov spectrum of electron density fluctuations in a turbulent medium. In contrast, the measured τsc's for highly dispersed pulsars in the central region of the Galaxy are larger than expected and show a spectrum which is flatter than the Kolmogorov law. We analyse the first measurements of spectral indices of scatter broadening over the full known DM range and discuss possible explanations for the anomalous scattering behaviour along peculiar lines of sight (LOS).

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…

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fister, T. T.; Seidler, G. T.; Rehr, J. J.

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 broadeningmore » 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.« less

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

NASA Astrophysics Data System (ADS)

Zhavoronkov, N.; Driben, R.; Bregadiolli, B. A.; Nalin, M.; Malomed, B. A.

2011-05-01

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

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.

Fundamental edge broadening effects during focused electron beam induced nanosynthesis

DOE PAGES

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

2015-02-16

In this study, we explore lateral broadening effects of 3D structures fabricated through focused electron beam induced deposition using MeCpPt(IV)Me 3 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 tomore » even more complex proximity effects that significantly reduce lateral edge sharpness and thus should be avoided if desiring high lateral resolution.« less

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.

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.

Nitrogen-broadened lines of ethane at 150 K

NASA Technical Reports Server (NTRS)

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

1985-01-01

Spectral transmittance has been measured in the nu9 fundamental band of C2H6 at 150 K using a Fourier transform spectrometer with apodized spectral resolution of 0.06/cm. Comparison of observed spectral transmittance with a line-by-line computation using the spectral catalog of Atakan et al. (1983) has yielded N2-broadened half-widths at 150 K.

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.

The Effects of Career Broadening on Leadership Development

DTIC Science & Technology

2007-03-01

development of its officer corps. Specifically, the study sought to find significant relationships between incidents of career broadening in the...Introduction Introduction In organizations where change is necessary, which is most organizations today, strong leadership relationships are required (Yukl...Holton, 2004; Mumford, Marks et al., 2000; Campion et. al., 1994; McCauley et. al., 1994). The relationship between personality and leadership is

Atomic Force Microscopy Nanomechanical Mapping Visualizes Interfacial Broadening between Networks Due to Chemical Exchange Reactions.

PubMed

He, Changfei; Shi, Shaowei; Wu, Xuefei; Russell, Thomas P; Wang, Dong

2018-06-06

The interfacial broadening between two different epoxy networks having different moduli was nanomechanically mapped. The interfacial broadening of the two networks produced an interfacial zone having a gradient in the concentration and, hence, properties of the original two networks. This interfacial broadening of the networks leads to the generation of a new network with a segmental composition corresponding to a mixture of the original two network segments. The intermixing of the two, by nature of the exchange reactions, was on the segmental level. By mapping the time dependence of the variation in the modulus at different temperatures, the kinetics of the exchange reaction was measured and, by varying the temperature, the activation energy of the exchange reaction was determined.

Positive mood broadens visual attention to positive stimuli.

PubMed

Wadlinger, Heather A; Isaacowitz, Derek M

2006-03-01

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.

The Role of Positive Emotions in Positive Psychology: The Broaden-and-Build Theory of Positive Emotions.

ERIC Educational Resources Information Center

Fredrickson, Barbara L.

2001-01-01

Describes the broaden-and-build theory of positive emotions, situating it within the field of positive psychology. The theory posits that experiences of positive emotions broaden people's momentary thought-action repertoires, which in turn build their enduring personal resources (physical, intellectual, social, and psychological). Reviews…

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

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…

Towards Broadening the Audience

NASA Astrophysics Data System (ADS)

Sakimoto, P. J.

2008-06-01

The strand Towards Broadening the Audience was intended to seed thoughtful conversations about building bridges for outreach programs across cultural barriers. Many participants spoke about progress in increasing the diversity of their outreach audiences, but it was new voices from time-honored sources that offered fundamentally new wisdom. From the religious traditions and tensions that mark the Holy Land came the simple concept of bringing unity through teaching the commonalities found in basic concepts of the observed sky. From Mayan traditions, both contemporary and ancient, came the reminder that the sky is intimately connected to all aspects of our lives. Astronomy outreach should therefore be a part of much larger family and community celebrations. Ideas such as these offer renewed hope for major advances in bringing space science outreach to much broader audiences. They tell us about the importance of learning from voices with perspectives different from our own, and of building partnerships based upon genuine cross-cultural understanding and mutual love of the sky.

Mechanism of asymmetric lineshape broadening in GaAs1-xNx Raman spectra

NASA Astrophysics Data System (ADS)

Mialitsin, Aleksej; Fluegel, Brian; Ptak, Aaron; Mascarenhas, Angelo

2012-07-01

Resonance Raman spectroscopy is used to probe the asymmetric broadening of the LO phonon linewidth in a dilute GaAs1-xNx alloy (x=0.41%). Electronic Raman scattering from a broad continuum is observed that gets enhanced concurrently with the LO phonon linewidth under resonance. The Fano interaction between the LO phonon and the electronic continuum is used to develop a model that satisfactorily explains the origin of the asymmetric LO phonon linewidth broadening in this abnormal alloy as arising due to coupling between the discrete and the continuum configurations.

Amplifying modeling for broad bandwidth pulse in Nd:glass based on hybrid-broaden mechanism

NASA Astrophysics Data System (ADS)

Su, J.; Liu, L.; Luo, B.; Wang, W.; Jing, F.; Wei, X.; Zhang, X.

2008-05-01

In this paper, the cross relaxation time is proposed to combine the homogeneous and inhomogeneous broaden mechanism for broad bandwidth pulse amplification model. The corresponding velocity equation, which can describe the response of inverse population on upper and low energy level of gain media to different frequency of pulse, is also put forward. The gain saturation and energy relaxation effect are also included in the velocity equation. Code named CPAP has been developed to simulate the amplifying process of broad bandwidth pulse in multi-pass laser system. The amplifying capability of multi-pass laser system is evaluated and gain narrowing and temporal shape distortion are also investigated when bandwidth of pulse and cross relaxation time of gain media are different. Results can benefit the design of high-energy PW laser system in LFRC, CAEP.

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…

Lifetime broadening in GaAs-AlGaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kucharska, A.I.; Robbins, D.J.

1990-03-01

Experimental observations of spontaneous emission spectra from GaAs-AlGaAs quantum well lasers show that spectral broadening should be included in any realistic model of laser performance. The authors describe a model of the lifetime broadening due to intraband Auger processes of the Landsberg type and develop it for the case of electron-electron scattering in a 2-D system. They apply the model to the calculation of gain and spontaneous emission spectra and gain-current relationships in short-wavelength GaAs-AlGaAs quantum well lasers, and compare their results with those obtained using both a fixed intraband scattering time and one that varies as {ital n}{sup 1/2},more » where {ital n} is the volume injected carrier density.« less

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.

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

Magnetic Field Measurements In Magnetized Plasmas Using Zeeman Broadening Diagnostics

NASA Astrophysics Data System (ADS)

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

2017-10-01

The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. This method is limited when plasma conditions are such that the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. We have measured magnetic fields in magnetized laser plasmas under conditions where the Zeeman splitting was not spectrally resolved. The magnetic field strength was determined from the difference in widths of two doublet components, using an idea proposed by Tessarin et al. (2011). 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. 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. Radial magnetic field and electron density profiles were measured within the plasma plume. This work was supported by the DOE/OFES Grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.

Measurements of air-broadened and nitrogen-broadened Lorentz width coefficients and pressure shift coefficients in the nu4 and nu2 bands of C-12H4

NASA Technical Reports Server (NTRS)

Rinsland, Curtis P.; Smith, Mary Ann H.; Devi, V. Malathy; Benner, D. Chris

1988-01-01

Air-broadened and N2-broadened halfwidth and pressure shift coefficients of 294 transitions in the nu4 and nu2 bands of C-12H4 have been measured from laboratory absorption spectra recorded at room temperature with the Fourier transform spectrometer in the McMath solar telescope facility of the National Solar Observatory. Total pressures of up to 551 Torr were employed with absorption paths of 5-150 cm, CH4 volume mixing ratios of 2.6 percent or less, and resolutions of 0.005 and 0.01/cm. A nonlinear least-squares spectral fitting technique has been utilized in the analysis of the twenty-five measured spectra. Lines up to J double-prime = 18 in the nu4 band and J double-prime = 15 in the nu2 band have been analyzed.

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.

Theoretical calculation of CH3F/N2-broadening coefficients and their temperature dependence

NASA Astrophysics Data System (ADS)

Jellali, C.; Maaroufi, N.; Aroui, H.

2018-07-01

Using Robert and Bonamy formalism (with parabolic and exact trajectories) based on the semi-classical impact theory, N2-broadening coefficients of methyl fluoride CH3F were calculated for transitions belonging to the PP-, PQ-, PR-, RP-, RQ- and RR- sub-branches of the ν6 perpendicular band near 8.5 μm. The calculations showed the predominance of the dipole-quadruple interaction. The J and K rotational quantum numbers dependencies of the computed coefficients that are consistent with previous measurements were clearly observed in this study. For a fixed value of J, we noticed a decrease in the broadening coefficients, which was more significant at lower J values. In order to deduce the temperature exponent, the N2-broadening coefficients of CH3F were calculated at various temperatures of atmospheric interest between 183 and 296 K with J ≤ 60 and K ≤ 10. These exponents were, in general, J-dependent and K-independent, except for K close to J.

Line shape parameters of air-broadened water vapor transitions in the ν 1 and ν 3 spectral region

DOE PAGES

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien; ...

2017-11-26

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H 2O and air-broadened H 2O in the regions of the ν 1 and ν 3 bands (3450–4000 cm -1) at different pressures, temperatures and volume mixing ratios of H 2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. Furthermore, the resolution of the spectra recorded with themore » 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm -1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H 2O-air and 8 transition pairs for H 2O-H 2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N 2- and O 2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. Finally, the measurements and calculations are compared with each other and with similar parameters reported in the literature.« less

Line shape parameters of air-broadened water vapor transitions in the ν1 and ν3 spectral region

NASA Astrophysics Data System (ADS)

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien; Renaud, Candice L.; Chris Benner, D.; Smith, Mary Ann H.; Blake, Thomas A.; Sams, Robert L.

2018-06-01

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H2O and air-broadened H2O in the regions of the ν1 and ν3 bands (3450-4000 cm-1) at different pressures, temperatures and volume mixing ratios of H2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. The resolution of the spectra recorded with the 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm-1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H2O-air and 8 transition pairs for H2O-H2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N2- and O2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. The measurements and calculations are compared with each other and with similar parameters reported in the literature.

Line shape parameters of air-broadened water vapor transitions in the ν 1 and ν 3 spectral region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malathy Devi, V.; Gamache, Robert R.; Vispoel, Bastien

A Bruker IFS-120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington was used to record a series of spectra of pure H 2O and air-broadened H 2O in the regions of the ν 1 and ν 3 bands (3450–4000 cm -1) at different pressures, temperatures and volume mixing ratios of H 2O in air. Eighteen high-resolution, high signal-to-noise (S/N) ratio absorption spectra were recorded at T = 268, 296 and 353 K using two temperature-controlled absorption cells with path lengths of 9.906(1) and 19.95(1) cm. Furthermore, the resolution of the spectra recorded with themore » 9.906 cm and 19.95 cm absorption cells was 0.006 and 0.008 cm -1, respectively. A multispectrum nonlinear least squares fitting technique was employed to fit all the eighteen spectra simultaneously to retrieve 313 accurate line positions, 315 intensities, 229 Lorentz air-broadened half-width and 213 air-shift coefficients and their temperature dependences (136 for air-broadened width and 128 for air-shift coefficients, respectively). Room temperature self-broadened half-width coefficients for 209 transitions and self-shift coefficients for 106 transitions were also measured. Line mixing coefficients were experimentally determined for isolated sets of 10 transition pairs for H 2O-air and 8 transition pairs for H 2O-H 2O using the off-diagonal relaxation matrix element formalism, and 85 quadratic speed dependence parameters were measured. Modified Complex Robert-Bonamy (MCRB) calculations of self-, and air-broadened (from N 2- and O 2-broadening) half-width and air-shift coefficients, and temperature dependence exponents of air-broadened half-width coefficients are made. Finally, the measurements and calculations are compared with each other and with similar parameters reported in the literature.« less

H2-,He-and CO2-line broadening coefficients and pressure shifts for the HITRAN database

NASA Astrophysics Data System (ADS)

Wilzewski, Jonas; Gordon, Iouli E.; Rothman, Laurence S.

2014-06-01

To increase the potential of the HITRAN database in astronomy, experimental and theoretical line broadening coefficients and line shifts of molecules of planetary interest broadened by H2,He,and CO2 have been assembled from available peer-reviewed sources. Since H2 and He are major constituents in the atmospheres of gas giants, and CO2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for studying planetary atmospheres. The collected data were used to create semi-empirical models for complete data sets from the microwave to the UV part of the spectrum of the studied molecules. The presented work will help identify the need for further investigations of broadening and shifting of spectral lines.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 N e ~10 17 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

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 N e ~10 17 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

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…

The importance of nuclear quantum effects in spectral line broadening of optical spectra and electrostatic properties in aromatic chromophores.

PubMed

Law, Y K; Hassanali, A A

2018-03-14

In this work, we examine the importance of nuclear quantum effects on capturing the line broadening and vibronic structure of optical spectra. We determine the absorption spectra of three aromatic molecules indole, pyridine, and benzene using time dependent density functional theory with several molecular dynamics sampling protocols: force-field based empirical potentials, ab initio simulations, and finally path-integrals for the inclusion of nuclear quantum effects. We show that the absorption spectrum for all these chromophores are similarly broadened in the presence of nuclear quantum effects regardless of the presence of hydrogen bond donor or acceptor groups. We also show that simulations incorporating nuclear quantum effects are able to reproduce the heterogeneous broadening of the absorption spectra even with empirical force fields. The spectral broadening associated with nuclear quantum effects can be accounted for by the broadened distribution of chromophore size as revealed by a particle in the box model. We also highlight the role that nuclear quantum effects have on the underlying electronic structure of aromatic molecules as probed by various electrostatic properties.

The importance of nuclear quantum effects in spectral line broadening of optical spectra and electrostatic properties in aromatic chromophores

NASA Astrophysics Data System (ADS)

Law, Y. K.; Hassanali, A. A.

2018-03-01

In this work, we examine the importance of nuclear quantum effects on capturing the line broadening and vibronic structure of optical spectra. We determine the absorption spectra of three aromatic molecules indole, pyridine, and benzene using time dependent density functional theory with several molecular dynamics sampling protocols: force-field based empirical potentials, ab initio simulations, and finally path-integrals for the inclusion of nuclear quantum effects. We show that the absorption spectrum for all these chromophores are similarly broadened in the presence of nuclear quantum effects regardless of the presence of hydrogen bond donor or acceptor groups. We also show that simulations incorporating nuclear quantum effects are able to reproduce the heterogeneous broadening of the absorption spectra even with empirical force fields. The spectral broadening associated with nuclear quantum effects can be accounted for by the broadened distribution of chromophore size as revealed by a particle in the box model. We also highlight the role that nuclear quantum effects have on the underlying electronic structure of aromatic molecules as probed by various electrostatic properties.

Probing transverse momentum broadening via jet-related angular correlations in relativistic nuclear collisions

NASA Astrophysics Data System (ADS)

Chen, Lin; Qin, Guang-You; Wei, Shu-Yi; Xiao, Bo-Wen; Zhang, Han-Zhong

2017-11-01

Jet-related correlations have been regarded as important tools for studying jet-medium interaction and jet quenching in relativistic heavy-ion collisions at RHIC and the LHC. Here we present our recent work [L. Chen, G.-Y. Qin, S.-Y. Wei, B.-W. Xiao, H.-Z. Zhang, Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions, arxiv:arXiv:1607.01932] and show that the back-to-back angular correlations in dijet, dihadron and hadron-jet measurements can be utilized as a quantitative tool to probe the medium-induced transverse momentum broadening and to extract jet quenching parameter q̂. By comparing with the dihadron and hadron-jet angular correlation data at RHIC, we obtain the medium-induced transverse momentum broadening, averaged over different jet paths, 〈 p⊥2 〉 ∼ 13 GeV2 for a quark jet in most central Au-Au collisions at 200A GeV. Future experiments with statistically improved data on jet-related (angular) correlations will allow us to obtain more precise knowledge of jet quenching parameter and parton-medium interaction in high-energy nuclear collisions.

Cloud droplet size distribution broadening during diffusional growth: ripening amplified by deactivation and reactivation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Fan; Kollias, Pavlos; Shaw, Raymond A.

Cloud droplet size distributions (CDSDs), which are related to cloud albedo and lifetime, are usually broader in warm clouds than predicted from adiabatic parcel calculations. We investigate a mechanism for the CDSD broadening using a Lagrangian bin-microphysics cloud parcel model that considers the condensational growth of cloud droplets formed on polydisperse, sub-micrometer aerosols in an adiabatic cloud parcel that undergoes vertical oscillations, such as those due to cloud circulations or turbulence. Results show that the CDSD can be broadened during condensational growth as a result of Ostwald ripening amplified by droplet deactivation and reactivation, which is consistent with Korolev (1995).more » The relative roles of the solute effect, curvature effect, deactivation and reactivation on CDSD broadening are investigated. Deactivation of smaller cloud droplets, which is due to the combination of curvature and solute effects in the downdraft region, enhances the growth of larger cloud droplets and thus contributes particles to the larger size end of the CDSD. Droplet reactivation, which occurs in the updraft region, contributes particles to the smaller size end of the CDSD. In addition, we find that growth of the largest cloud droplets strongly depends on the residence time of cloud droplet in the cloud rather than the magnitude of local variability in the supersaturation fluctuation. This is because the environmental saturation ratio is strongly buffered by smaller cloud droplets. Two necessary conditions for this CDSD broadening, which generally occur in the atmosphere, are: (1) droplets form on polydisperse aerosols of varying hygroscopicity and (2) the cloud parcel experiences upwards and downwards motions. Therefore we expect that this mechanism for CDSD broadening is possible in real clouds. Our results also suggest it is important to consider both curvature and solute effects before and after cloud droplet activation in a cloud model. The importance

Cloud droplet size distribution broadening during diffusional growth: ripening amplified by deactivation and reactivation

DOE PAGES

Yang, Fan; Kollias, Pavlos; Shaw, Raymond A.; ...

2017-12-06

Cloud droplet size distributions (CDSDs), which are related to cloud albedo and lifetime, are usually broader in warm clouds than predicted from adiabatic parcel calculations. We investigate a mechanism for the CDSD broadening using a Lagrangian bin-microphysics cloud parcel model that considers the condensational growth of cloud droplets formed on polydisperse, sub-micrometer aerosols in an adiabatic cloud parcel that undergoes vertical oscillations, such as those due to cloud circulations or turbulence. Results show that the CDSD can be broadened during condensational growth as a result of Ostwald ripening amplified by droplet deactivation and reactivation, which is consistent with Korolev (1995).more » The relative roles of the solute effect, curvature effect, deactivation and reactivation on CDSD broadening are investigated. Deactivation of smaller cloud droplets, which is due to the combination of curvature and solute effects in the downdraft region, enhances the growth of larger cloud droplets and thus contributes particles to the larger size end of the CDSD. Droplet reactivation, which occurs in the updraft region, contributes particles to the smaller size end of the CDSD. In addition, we find that growth of the largest cloud droplets strongly depends on the residence time of cloud droplet in the cloud rather than the magnitude of local variability in the supersaturation fluctuation. This is because the environmental saturation ratio is strongly buffered by smaller cloud droplets. Two necessary conditions for this CDSD broadening, which generally occur in the atmosphere, are: (1) droplets form on polydisperse aerosols of varying hygroscopicity and (2) the cloud parcel experiences upwards and downwards motions. Therefore we expect that this mechanism for CDSD broadening is possible in real clouds. Our results also suggest it is important to consider both curvature and solute effects before and after cloud droplet activation in a cloud model. The importance

Cloud droplet size distribution broadening during diffusional growth: ripening amplified by deactivation and reactivation

NASA Astrophysics Data System (ADS)

Yang, Fan; Kollias, Pavlos; Shaw, Raymond A.; Vogelmann, Andrew M.

2018-05-01

Cloud droplet size distributions (CDSDs), which are related to cloud albedo and rain formation, are usually broader in warm clouds than predicted from adiabatic parcel calculations. We investigate a mechanism for the CDSD broadening using a moving-size-grid cloud parcel model that considers the condensational growth of cloud droplets formed on polydisperse, submicrometer aerosols in an adiabatic cloud parcel that undergoes vertical oscillations, such as those due to cloud circulations or turbulence. Results show that the CDSD can be broadened during condensational growth as a result of Ostwald ripening amplified by droplet deactivation and reactivation, which is consistent with early work. The relative roles of the solute effect, curvature effect, deactivation and reactivation on CDSD broadening are investigated. Deactivation of smaller cloud droplets, which is due to the combination of curvature and solute effects in the downdraft region, enhances the growth of larger cloud droplets and thus contributes particles to the larger size end of the CDSD. Droplet reactivation, which occurs in the updraft region, contributes particles to the smaller size end of the CDSD. In addition, we find that growth of the largest cloud droplets strongly depends on the residence time of cloud droplet in the cloud rather than the magnitude of local variability in the supersaturation fluctuation. This is because the environmental saturation ratio is strongly buffered by numerous smaller cloud droplets. Two necessary conditions for this CDSD broadening, which generally occur in the atmosphere, are as follows: (1) droplets form on aerosols of different sizes, and (2) the cloud parcel experiences upwards and downwards motions. Therefore we expect that this mechanism for CDSD broadening is possible in real clouds. Our results also suggest it is important to consider both curvature and solute effects before and after cloud droplet activation in a cloud model. The importance of this mechanism

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...

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…

Exciton broadening and band renormalization due to Dexter-like intervalley coupling

NASA Astrophysics Data System (ADS)

Bernal-Villamil, Ivan; Berghäuser, Gunnar; Selig, Malte; Niehues, Iris; Schmidt, Robert; Schneider, Robert; Tonndorf, Philipp; Erhart, Paul; Michaelis de Vasconcellos, Steffen; Bratschitsch, Rudolf; Knorr, Andreas; Malic, Ermin

2018-04-01

A remarkable property of atomically thin transition metal dichalcogenides (TMDs) is the possibility to selectively address single valleys by circularly polarized light. In the context of technological applications, it is very important to understand possible intervalley coupling mechanisms. Here, we show how the Dexter-like intervalley coupling mixes A and B states from opposite valleys leading to a significant broadening γB_{1s} of the B1s exciton. The effect is much more pronounced in tungsten-based TMDs, where the coupling excitonic states are quasi-resonant. We calculate a ratio γB_{1s}/γA_{1s}≈ 4.0 , which is in good agreement with the experimentally measured value of 3.9+/-0.7 . In addition to the broadening effect, the Dexter-like intervalley coupling also leads to a considerable energy renormalization resulting in an increased energetic distance between A1s and B1s states.

Broadening Participation in the Society for Integrative and Comparative Biology

PubMed Central

Wilga, Cheryl A.D.; Nishiguchi, Michele; Tsukimura, Brian

2017-01-01

Synopsis The goal of the Society for Integrative and Comparative Biology’s Broadening Participation Committee (SICB BPC) is to increase the number of underrepresented group (URG) members within the society and to expand their capabilities as future researchers and leaders within SICB. Our short-term 10-year goal was to increase the recruitment and retention of URG members in the society by 10%. Our long-term 25-year goal is to increase the membership of URG in the society through recruitment and retention until the membership demographic mirrors that of the US Census. Our plans to accomplish this included establishment of a formal standing committee, establishment of a moderate budget to support BPC activities, hosting professional development workshops, hosting diversity and mentor socials, and obtaining grant funds to supplement our budget. This paper documents broadening participation activities in the society, discusses the effectiveness of these activities, and evaluates BPC goals after 5 years of targeted funded activities. Over the past 5 years, the number of URG members rose by 5.2% to a total of 16.2%, members who report ethnicity and gender increased by 25.2% and 18%, respectively, and the number of members attending BPC activities has increased to 33% by 2016. SICB has made significant advances in broadening participation, not only through increased expenditures, but also with a commitment by its members and leadership to increase diversity. Most members realize that increasing diversity will both improve the Society’s ability to develop different approaches to tackling problems within integrative biology, and help solve larger global issues that are evident throughout science and technology fields. In addition, having URG members as part of the executive committee would provide other URG members role models within the society, as well as have a voice in the leadership that represents diversity and inclusion for all scientists. PMID:28881934

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…

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)

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%.

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.

The Organization as Client: Broadening the Concept of Employee Assistance Programs.

ERIC Educational Resources Information Center

Googins, Bradley; Davidson, Bruce N.

1993-01-01

Notes that many employee assistance programs (EAPs) are broadening their function to address rapidly changing human and social issues of environments in which they operate, refocusing practice to include organization as the client. Discusses traditional EAP practice, evolution of EAPs, changes confronting corporations, and alternative model in…

Doppler broadening of neutron-induced resonances using ab initio phonon spectrum

NASA Astrophysics Data System (ADS)

Noguere, G.; Maldonado, P.; De Saint Jean, C.

2018-05-01

Neutron resonances observed in neutron cross section data can only be compared with their theoretical analogues after a correct broadening of the resonance widths. This broadening is usually carried out by two different theoretical models, namely the Free Gas Model and the Crystal Lattice Model, which, however, are only applicable under certain assumptions. Here, we use neutron transmission experiments on UO2 samples at T=23.7 K and T=293.7 K, to investigate the limitations of these models when an ab initio phonon spectrum is introduced in the calculations. Comparisons of the experimental and theoretical transmissions highlight the underestimation of the energy transferred at low temperature and its impact on the accurate determination of the radiation widths Γ_{γ_{λ}} of the 238U resonances λ. The observed deficiency of the model represents an experimental evidence that the Debye-Waller factor is not correctly calculated at low temperature near the Neel temperature ( TN=30.8 K).

Action Potential Broadening in Capsaicin-Sensitive DRG Neurons from Frequency-Dependent Reduction of Kv3 Current

PubMed Central

Liu, Pin W.; Blair, Nathaniel T.

2017-01-01

Action potential (AP) shape is a key determinant of cellular electrophysiological behavior. We found that in small-diameter, capsaicin-sensitive dorsal root ganglia neurons corresponding to nociceptors (from rats of either sex), stimulation at frequencies as low as 1 Hz produced progressive broadening of the APs. Stimulation at 10 Hz for 3 s resulted in an increase in AP width by an average of 76 ± 7% at 22°C and by 38 ± 3% at 35°C. AP clamp experiments showed that spike broadening results from frequency-dependent reduction of potassium current during spike repolarization. The major current responsible for frequency-dependent reduction of overall spike-repolarizing potassium current was identified as Kv3 current by its sensitivity to low concentrations of 4-aminopyridine (IC50 <100 μm) and block by the peptide inhibitor blood depressing substance I (BDS-I). There was a small component of Kv1-mediated current during AP repolarization, but this current did not show frequency-dependent reduction. In a small fraction of cells, there was a component of calcium-dependent potassium current that showed frequency-dependent reduction, but the contribution to overall potassium current reduction was almost always much smaller than that of Kv3-mediated current. These results show that Kv3 channels make a major contribution to spike repolarization in small-diameter DRG neurons and undergo frequency-dependent reduction, leading to spike broadening at moderate firing frequencies. Spike broadening from frequency-dependent reduction in Kv3 current could mitigate the frequency-dependent decreases in conduction velocity typical of C-fiber axons. SIGNIFICANCE STATEMENT Small-diameter dorsal root ganglia (DRG) neurons mediating nociception and other sensory modalities express many types of potassium channels, but how they combine to control firing patterns and conduction is not well understood. We found that action potentials of small-diameter rat DRG neurons showed spike

Pressure broadening of the ((dt. mu. )dee)/sup */ formation resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, J.S.; Leon, M.; Padial, N.T.

1988-01-01

The treatment of ((dt..mu..)dee)/sup */ formation at high densities as a pressure broadening process is discussed. The quasistatic approximation is shown to satisfy the usual conditions of muon-catalyzed fusion better than does the impact approximation. Complete accurate results are shown for the impact approximation, and a preliminary rough treatment is presented to illustrate the quasistatic approximation. 13 refs., 8 figs.

Spectral broadening of optical transitions in InAs/GaAs coupled quantum dot pairs

NASA Astrophysics Data System (ADS)

Kumar, P.; Czarnocki, C.; Jennings, C.; Casara, J.; Monteros, A. L.; Zahbihi, N.; Scheibner, M.; Economou, S. E.; Bracker, A. S.; Pursley, B. C.; Gammon, D.; Carter, S. G.

The optical transitions in InAs/GaAs coupled quantum dot (CQD) pairs are investigated experimentally. These coupled dot systems provide new means to study the interaction of quantum states with the mechanical modes of the crystal environment. Here, the line width and line shape of CQD optical transitions are analyzed in detail as a function of temperature, excitation power, excitation energy, and tunnel coupling strength. A significant line broadening, up to 25 times the typical lifetime-limited linewidth of single-dot excitons, is being observed at level anti-crossings where the coherent tunnel coupling between spatially direct and indirect exciton states is considerable. The experimental observations are compared with theoretical predictions where linewidth broadening at anti-crossings is attributed to the phonon assisted transitions, and found to be strongly dependent on the energy splitting of the two exciton branches. This work focuses on understanding the linewidth broadening due to the pure dephasing, and fundamental aspects of the interaction of these systems with the local environment. This work was supported by the Defense Threat Reduction Agency, Basic Research Award HDTRA1-15-1-0011.

The blues broaden, but the nasty narrows: attentional consequences of negative affects low and high in motivational intensity.

PubMed

Gable, Philip; Harmon-Jones, Eddie

2010-02-01

Positive and negative affects high in motivational intensity cause a narrowing of attentional focus. In contrast, positive affects low in motivational intensity cause a broadening of attentional focus. The attentional consequences of negative affects low in motivational intensity have not been experimentally investigated. Experiment 1 compared the attentional consequences of negative affect low in motivational intensity (sadness) relative to a neutral affective state. Results indicated that low-motivation negative affect caused attentional broadening. Experiment 2 found that disgust, a high-motivation negative affect not previously investigated in attentional studies, narrowed attentional focus. These experiments support the conceptual model linking high-motivation affective states to narrowed attention and low-motivation affective states to broadened attention.

Experimental investigation of the effect of pump incoherence on nonlinear pump spectral broadening and continuous-wave supercontinuum generation

NASA Astrophysics Data System (ADS)

Martin-Lopez, S.; Carrasco-Sanz, A.; Corredera, P.; Abrardi, L.; Hernanz, M. L.; Gonzalez-Herraez, M.

2006-12-01

The development of high-power cw fiber lasers has triggered a great interest in the phenomena of nonlinear pump spectral broadening and cw supercontinuum generation. These effects have very convenient applications in Raman amplification, optical fiber metrology, and fiber sensing. In particular, it was recently shown that pump incoherence has a strong impact in these processes. We study experimentally the effect of pump incoherence in nonlinear pump spectral broadening and cw supercontinuum generation in optical fibers. We show that under certain experimental conditions an optimum degree of pump incoherence yields the best performance in the broadening process. We qualitatively explain these results, and we point out that these results may have important implications in cw supercontinuum optimization.

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.

Kinematical line broadening and spatially resolved line profiles from AGN.

NASA Astrophysics Data System (ADS)

Schulz, H.; Muecke, A.; Boer, B.; Dresen, M.; Schmidt-Kaler, T.

1995-03-01

We study geometrical effects for emission-line broadening in the optically thin limit by integrating the projected line emissivity along prespecified lines of sight that intersect rotating or expanding disks or cone-like configurations. Analytical expressions are given for the case that emissivity and velocity follow power laws of the radial distance. The results help to interpret spatially resolved spectra and to check the reliability of numerical computations. In the second part we describe a numerical code applicable to any geometrical configuration. Turbulent motions, atmospheric seeing and effects induced by the size of the observing aperture are simulated with appropriate convolution procedures. An application to narrow-line Hα profiles from the central region of the Seyfert galaxy NGC 7469 is presented. The shapes and asymmetries as well as the relative strengths of the Hα lines from different spatial positions can be explained by emission from a nuclear rotating disk of ionized gas, for which the distribution of Hα line emissivity and the rotation curve are derived. Appreciable turbulent line broadening with a Gaussian σ of ~40% of the rotational velocity has to be included to obtain a satisfactory fit.

Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Archambault, S.; Griffin, S.; Archer, A.

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 broadenedmore » emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10{sup −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.« less

Stark broadening of Ca IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Alonso-Medina, A.; Colón, C.

2014-12-01

Ca IV emission lines are under the preview of Solar Ultraviolet Measurements of Emitted Radiation device aboard the Solar and Heliospheric Observatory. Also, lines of the Ca IV in planetary nebulae NGC 7027 were detected with the Short Wavelength Spectrometer on board the Infrared Space Observatory. These facts justify an attempt to provide new spectroscopic parameters of Ca IV. There are no theoretical or experimental Stark broadening data for Ca IV. Using the Griem semi-empirical approach and the COWAN code, we report in this paper calculated values of the Stark broadening parameters for 467 lines of Ca IV. They were calculated using a set of wavefunctions obtained by using Hartree-Fock relativistic calculations. These lines arising from 3s23p4ns (n = 4, 5), 3s23p44p, 3s23p4nd (n = 3, 4) configurations. Stark widths and shifts are presented for an electron density of 1017 cm-3 and temperatures T = 10 000, 20 000 and 50 200 K. As these data cannot be compared to others in the literature, we present an analysis of the different regularities of the values presented in this work.

Quantum Optics Models of EIT Noise and Power Broadening

NASA Astrophysics Data System (ADS)

Snider, Chad; Crescimanno, Michael; O'Leary, Shannon

2011-04-01

When two coherent beams of light interact with an atom they tend to drive the atom to a non-absorbing state through a process called Electromagnetically Induced Transparency (EIT). If the light's frequency dithers, the atom's state stochastically moves in and out of this non-absorbing state. We describe a simple quantum optics model of this process that captures the essential experimentally observed statistical features of this EIT noise, with a particular emphasis on understanding power broadening.

Homogeneous spectral broadening of pulsed terahertz quantum cascade lasers by radio frequency modulation.

PubMed

Wan, W J; Li, H; Cao, J C

2018-01-22

The authors present an experimental investigation of radio frequency modulation on pulsed terahertz quantum cascade lasers (QCLs) emitting around 4.3 THz. The QCL chip used in this work is based on a resonant phonon design which is able to generate a 1.2 W peak power at 10 K from a 400-µm-wide and 4-mm-long laser with a single plasmon waveguide. To enhance the radio frequency modulation efficiency and significantly broaden the terahertz spectra, the QCLs are also processed into a double-metal waveguide geometry with a Silicon lens out-coupler to improve the far-field beam quality. The measured beam patterns of the double-metal QCL show a record low divergence of 2.6° in vertical direction and 2.4° in horizontal direction. Finally we perform the inter-mode beat note and terahertz spectra measurements for both single plasmon and double-metal QCLs working in pulsed mode. Since the double-metal waveguide is more suitable for microwave signal transmission, the radio frequency modulation shows stronger effects on the spectral broadening for the double-metal QCL. Although we are not able to achieve comb operation in this work for the pulsed lasers due to the large phase noise, the homogeneous spectral broadening resulted from the radio frequency modulation can be potentially used for spectroscopic applications.

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…

Electromagnetically-induced-transparency intensity-correlation power broadening in a buffer gas

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Broadening Participation in the Society for Integrative and Comparative Biology.

PubMed

Wilga, Cheryl A D; Nishiguchi, Michele; Tsukimura, Brian

2017-07-01

The goal of the Society for Integrative and Comparative Biology's Broadening Participation Committee (SICB BPC) is to increase the number of underrepresented group (URG) members within the society and to expand their capabilities as future researchers and leaders within SICB. Our short-term 10-year goal was to increase the recruitment and retention of URG members in the society by 10%. Our long-term 25-year goal is to increase the membership of URG in the society through recruitment and retention until the membership demographic mirrors that of the US Census. Our plans to accomplish this included establishment of a formal standing committee, establishment of a moderate budget to support BPC activities, hosting professional development workshops, hosting diversity and mentor socials, and obtaining grant funds to supplement our budget. This paper documents broadening participation activities in the society, discusses the effectiveness of these activities, and evaluates BPC goals after 5 years of targeted funded activities. Over the past 5 years, the number of URG members rose by 5.2% to a total of 16.2%, members who report ethnicity and gender increased by 25.2% and 18%, respectively, and the number of members attending BPC activities has increased to 33% by 2016. SICB has made significant advances in broadening participation, not only through increased expenditures, but also with a commitment by its members and leadership to increase diversity. Most members realize that increasing diversity will both improve the Society's ability to develop different approaches to tackling problems within integrative biology, and help solve larger global issues that are evident throughout science and technology fields. In addition, having URG members as part of the executive committee would provide other URG members role models within the society, as well as have a voice in the leadership that represents diversity and inclusion for all scientists. © The Author 2017. Published by

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.

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

Relativistic quantum mechanical calculations of electron-impact broadening for spectral lines in Be-like ions

NASA Astrophysics Data System (ADS)

Duan, B.; Bari, M. A.; Wu, Z. Q.; Jun, Y.; Li, Y. M.; Wang, J. G.

2012-11-01

Aims: We present relativistic quantum mechanical calculations of electron-impact broadening of the singlet and triplet transition 2s3s ← 2s3p in four Be-like ions from N IV to Ne VII. Methods: In our theoretical calculations, the K-matrix and related symmetry information determined by the colliding systems are generated by the DARC codes. Results: A careful comparison between our calculations and experimental results shows good agreement. Our calculated widths of spectral lines also agree with earlier theoretical results. Our investigations provide new methods of calculating electron-impact broadening parameters for plasma diagnostics.

Measurements of argon-, helium-, hydrogen-, and nitrogen-broadened widths of methane lines near 9000 per cm

NASA Technical Reports Server (NTRS)

Fox, Kenneth; Jennings, Donald E.; Stern, Elizabeth A.; Hubbard, Rob

1988-01-01

Pressure-broadened widths of rotational-vibrational lines in CH4 have been measured at very high spectral resolution in the R-branch of the 3nu3 overtone. The broadening gases were Ar, He, H2, and N2. Results are presented as averages for J-multiplets at ambient temperature. The overall values (per cm per atm) for these R-branch lines are 0.0651 (CH4-Ar), 0.0508 (CH4-He), 0.0728 (CH4-H2), and 0.0715 (CH4-N2).

Spectral broadening in electroluminescence of white organic light-emitting diodes based on complementary colors

NASA Astrophysics Data System (ADS)

Kim, Young Min; Park, Young Wook; Choi, Jin Hwan; Ju, Byeong Kwon; Jung, Jae Hoon; Kim, Jai Kyeong

2007-01-01

The authors report the optical and electroluminescent (EL) properties of white organic light-emitting diodes (OLEDs) which have two emitters with similar structures: 1, 1, 4, 4-tetraphenyl-1, 3-butadiene and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline have an emission peak of 400nm around the near ultraviolet, and tris-(8-hydroxyquinoline) aluminum doped with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran has an emission peak of 580nm producing a yellow color. The EL spectra of the white OLED have shown a broadening through visual range from 400to780nm. This spectral broadening is related to an exciplex emission at the organic solid interface.

Action Potential Broadening in Capsaicin-Sensitive DRG Neurons from Frequency-Dependent Reduction of Kv3 Current.

PubMed

Liu, Pin W; Blair, Nathaniel T; Bean, Bruce P

2017-10-04

Action potential (AP) shape is a key determinant of cellular electrophysiological behavior. We found that in small-diameter, capsaicin-sensitive dorsal root ganglia neurons corresponding to nociceptors (from rats of either sex), stimulation at frequencies as low as 1 Hz produced progressive broadening of the APs. Stimulation at 10 Hz for 3 s resulted in an increase in AP width by an average of 76 ± 7% at 22°C and by 38 ± 3% at 35°C. AP clamp experiments showed that spike broadening results from frequency-dependent reduction of potassium current during spike repolarization. The major current responsible for frequency-dependent reduction of overall spike-repolarizing potassium current was identified as Kv3 current by its sensitivity to low concentrations of 4-aminopyridine (IC 50 <100 μm) and block by the peptide inhibitor blood depressing substance I (BDS-I). There was a small component of Kv1-mediated current during AP repolarization, but this current did not show frequency-dependent reduction. In a small fraction of cells, there was a component of calcium-dependent potassium current that showed frequency-dependent reduction, but the contribution to overall potassium current reduction was almost always much smaller than that of Kv3-mediated current. These results show that Kv3 channels make a major contribution to spike repolarization in small-diameter DRG neurons and undergo frequency-dependent reduction, leading to spike broadening at moderate firing frequencies. Spike broadening from frequency-dependent reduction in Kv3 current could mitigate the frequency-dependent decreases in conduction velocity typical of C-fiber axons. SIGNIFICANCE STATEMENT Small-diameter dorsal root ganglia (DRG) neurons mediating nociception and other sensory modalities express many types of potassium channels, but how they combine to control firing patterns and conduction is not well understood. We found that action potentials of small-diameter rat DRG neurons showed spike

[Participatory potential and deliberative function: a debate on broadening the scope of democracy through the health councils].

PubMed

Bispo Júnior, José Patrício; Gerschman, Sílvia

2013-01-01

This article reflects upon the relation between democracy and health councils. It seeks to analyze the councils as a space for broadening the scope of democracy. First, some characteristics and principles of the liberal democratic regime are presented, with an emphasis on the minimalist and procedural approach of decision-making. The fragilities of the representative model and the establishment of new relations between the Government and society are then discussed in light of the new social grammar and the complexity of the division between governmental and societal responsibilities. The principles of deliberative democracy and the idea of substantive democracy are subsequently presented. Broadening the scope of democracy is understood not only as the guarantee of civil and political rights, but also especially, of social rights. Lastly, based on discussion of the participation and deliberation categories, the health councils are analyzed as potential mechanisms for broadening the scope of democracy.

Covariance Matrix of a Double-Differential Doppler-Broadened Elastic Scattering Cross Section

NASA Astrophysics Data System (ADS)

Arbanas, G.; Becker, B.; Dagan, R.; Dunn, M. E.; Larson, N. M.; Leal, L. C.; Williams, M. L.

2012-05-01

Legendre moments of a double-differential Doppler-broadened elastic neutron scattering cross section on 238U are computed near the 6.67 eV resonance at temperature T = 103 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. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

Broadening of resistive transition and irreversibility line for epitaxial YBa2Cu3O7-δ thin film

NASA Astrophysics Data System (ADS)

Xiao-jun, Xu; Ke-bin, Li; Jun, Fang; Zhi-he, Wang; Xiao-wen, Cao

1996-04-01

The broadening of resistive transition of c axis oriented epitaxial YBCO thin film has been measured for three configurations: (1) Hparc and H ⊥ I; (2) Hparab plane and H ⊥ I; (3) Hparab plane and HparI in magnetic field up to 8 Tesla(T), and for different angle θ of magnetic field relative to the ab plane with H = 4T. The results obtained indicate that the broadening of resistive transition is mainly determined by the angle θ, but is hardly related to the angle α made between magnetic field and tran sport current in ab plane. This means that the broadening of resistive transition is not determined by flux motion drived by apparent Lorentz force. An expression of angular dependence of irreversibility line has been given.

Pressure broadening and frequency shift of the D 1 and D 2 lines of K in the presence of Ne and Kr

NASA Astrophysics Data System (ADS)

Wang, Xulin; Chen, Yao; Quan, Wei; Chi, Haotian; Fang, Jiancheng

2018-02-01

We present the results of pressure broadening and frequency shift of K D 1 and D 2 lines in presence of 1-4 amg of Neon gas and 1-5 amg of Krypton gas by laser absorption spectroscopy. Both pressure broadening and frequency shift are linearly related to gas density with high accuracy. The asymmetry of the absorption line shape caused by van der Waals potential was first found in the near-line wings of large density Kr in the experiment. We have also investigated the temperature dependence of the pressure broadening and frequency shift in a range of 353-403 K in Neon and 373-417 K in Krypton and compared the results of the pressure broadening and frequency shift with previous values.

Thoracic and diaphragmatic endometriosis: Single-institution experience using a novel broadened diagnostic criteria

PubMed

Larraín, Demetrio; Suárez, Francisco; Braun, Hernán; Chapochnick, Javier; Diaz, Lidia; Rojas, Iván

2018-06-05

To describe our experience with the multidisciplinary management of both thoracic/diaphragmatic endometriosis (TED), applying a broadened definition of the “thoracic endometriosis syndrome (TES)” to define cases. We present a retrospective series of consecutive patients affected by pathology-proven TED, treated at our institution, during a period of 7 years. Five women were included. Two cases were referred due to catamenial chest/shoulder pain, one due to recurrent catamenial pneumothorax, one due to new-onset diaphragmatic hernia. One patient had not thoracic symptoms, and diaphragmatic endometriosis was found during gynecologic laparoscopy for pelvic endometriosis. Endometriosis was histologically confirmed in all cases. After follow-up all patients remain asymptomatic. Broadened TES criteria could increase the incidence of TED and determine better knowledge of this condition. Multidisciplinary, minimally invasive surgery is effective and safe, but should be reserved to tertiary referral centers.

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…

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.

Nuclear p ⊥-broadening of an energetic parton pair

NASA Astrophysics Data System (ADS)

Cougoulic, Florian; Peigné, Stéphane

2018-05-01

We revisit the transverse momentum broadening of a fast parton pair crossing a nuclear medium, putting emphasis on the pair global color state, for any number of colors N and within the eikonal limit for parton propagation and the Gaussian approximation for the gluon field of the target. The pair transverse momentum probability distribution is derived in a kinetic equation approach, and is determined by an operator ℬ describing the possible transitions between the pair color states when crossing the medium. The exponential of ℬ encompasses the 4-point correlators of Wilson lines in the saturation formalism. We emphasize the relation of ℬ with the anomalous dimension matrices appearing in the study of soft gluon radiation associated to hard 2 → 2 partonic processes. In a well-chosen, orthonormal basis of the pair color states, we rederive ℬ for any type of parton pair, making maximal use of SU( N) invariants and using `birdtrack' color pictorial notations, providing a quite economical derivation of all previously known 4-point correlators (or equivalently, anomalous dimension matrices for 2 → 2 parton scattering). We discuss some general features of the pair transverse momentum distribution. The latter simplifies in the `compact pair expansion' which singles out the global charges (Casimirs) of the pair color states. This study should provide the necessary tools to address nuclear broadening of n-parton systems in phenomenology while highlighting the color structure of the process.

Stark broadening of resonant Cr II 3d5-3d44p spectral lines in hot stellar atmospheres

NASA Astrophysics Data System (ADS)

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

2013-07-01

New Stark broadening parameters of interest for the astrophysical, laboratory and technological plasma modelling, investigations and analysis for nine resonant Cr II multiplets have been determined within the semiclassical perturbation approach. In order to demonstrate one possibility for their usage in astrophysical plasma research, obtained results have been applied to the analysis of the Stark broadening influence on stellar spectral line shapes.

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.

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

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.

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).

The role of BK-type Ca2+-dependent K+ channels in spike broadening during repetitive firing in rat hippocampal pyramidal cells

PubMed Central

Shao, Li-Rong; Halvorsrud, Ragnhild; Borg-Graham, Lyle; Storm, Johan F

1999-01-01

The role of large-conductance Ca2+-dependent K+ channels (BK-channels; also known as maxi-K- or slo-channels) in spike broadening during repetitive firing was studied in CA1 pyramidal cells, using sharp electrode intracellular recordings in rat hippocampal slices, and computer modelling. Trains of action potentials elicited by depolarizing current pulses showed a progressive, frequency-dependent spike broadening, reflecting a reduced rate of repolarization. During a 50 ms long 5 spike train, the spike duration increased by 63·6 ± 3·4% from the 1st to the 3rd spike. The amplitude of the fast after-hyperpolarization (fAHP) also rapidly declined during each train. Suppression of BK-channel activity with (a) the selective BK-channel blocker iberiotoxin (IbTX, 60 nM), (b) the non-peptidergic BK-channel blocker paxilline (2–10 μM), or (c) calcium-free medium, broadened the 1st spike to a similar degree (≈60%). BK-channel suppression also caused a similar change in spike waveform as observed during repetitive firing, and eliminated (occluded) most of the spike broadening during repetitive firing. Computer simulations using a reduced compartmental model with transient BK-channel current and 10 other active ionic currents, produced an activity-dependent spike broadening that was strongly reduced when the BK-channel inactivation mechanism was removed. These results, which are supported by recent voltage-clamp data, strongly suggest that in CA1 pyramidal cells, fast inactivation of a transient BK-channel current (ICT), substantially contributes to frequency-dependent spike broadening during repetitive firing. PMID:10562340

Virus-Specific T Cells: Broadening Applicability.

PubMed

Barrett, A John; Prockop, Susan; Bollard, Catherine M

2018-01-01

Virus infection remains an appreciable cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Although pharmacotherapy and/or antibody therapy may help prevent or treat viral disease, these drugs are expensive, toxic, and often ineffective due to primary or secondary resistance. Further, effective treatments are limited for many infections (eg, adenovirus, BK virus), which are increasingly detected after alternative donor transplants. These deficiencies in conventional therapeutics have increased interest in an immunotherapeutic approach to viral disorders, leading to adoptive transfer of virus-specific cytotoxic T lymphocytes (VSTs), which can rapidly reconstitute antiviral immunity post-transplantation without causing graft-versus-host disease. This review will explore how the VST field has improved outcomes for many patients with life-threatening viral infections after HSCT, and how to broaden applicability beyond the "patient-specific" products, as well as extending to other viral diseases even outside the context of HSCT. Copyright © 2017 The American Society for Blood and Marrow Transplantation. All rights reserved.

Self-Broadening and Self-Shift Coefficients in the Fundamental Band of 12C 16O

NASA Technical Reports Server (NTRS)

Devi, Malathy V.; Benner, D. Chris; Smith, Mary Ann H.; Rinsland, Curtis P.

1998-01-01

High quality and precise measurements of self-broadened and self-shift coefficients in the fundamental band of C-12O-16 were made using spectra recorded at room temperature with the high-resolution (0.0027 cm(exp -1)) McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak, Arizona. The spectral region under investigation (2008-2247 cm(exp -1)) contains the P(31) to R(31) transitions. The data were obtained using a high-purity natural isotopic sample ofcarbon monoxide and two absorption cells with pathlengths of 4.08 and 9.98 cm, respectively. Various pressures of CO were used, ranging between 0.25 and 201.2 Torr. The results were obtained by analyzing five spectra simultaneously, using a multispectrum nonlinear least-squares fitting technique. The self-broadened coefficients ranged from 0.0426(2) cm(exp -1) atm(exp -1) at 296 K to 0.0924(2) cm(exp -1) atm(exp -1) at 296 K, while the pressure-induced shift coefficients varied between -0.0042(3) cm(exp -1) atm(exp -1) at 296 K and +0.0005(l) cm(exp -1) atm(exp -1) at 296 K. The value in parentheses is the estimated uncertainty in units of the last digit. The self-broadened coefficients of lines with same values of m in the P and R branches agree close to within experimental uncertainties while the self-shift coefficients showed considerable variation within and between the two branches. The mean value of the ratios of P branch to R branch self-broadened coefficients was found to be 1.01 with a standard deviation of + or - 0.01. Comparisons of the results with other published data were made.

GOLD (GEO Opportunities for Leadership in Diversity): Building capacity for broadening participation in the Geosciences

NASA Astrophysics Data System (ADS)

Jones, B.; Patino, L. C.; Rom, E. L.; Adams, A.

2017-12-01

The geosciences continue to lag other science, technology, engineering, and mathematics (STEM) disciplines in the engagement, recruitment and retention of traditionally underrepresented and underserved groups, 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 this area. 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 to achieve success must be developed. 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 change management, leadership development research, and pedagogies for professional development will not only engender fresh thinking and innovative approaches for preparing and empowering

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.

Noble-gas-induced collisional broadening of the 3P12-3P32 transition of sodium measured by the trilevel-echo technique

NASA Astrophysics Data System (ADS)

Mossberg, T. W.; Whittaker, E.; Kachru, R.; Hartmann, S. R.

1980-11-01

A variant of the trilevel-echo effect is observed and utilized to measure the effective cross section for broadening of the 3P12-3P32 transition of sodium by the noble gases. The cross section measured here should be the same as the broadening cross section obtained from a direct measurement of the collisionally broadened 3P12-3P32 transition linewidth (if such a measurement were possible). The new echo, the "inverted-difference-frequency" (IDF) trilevel echo, is well suited to the study of transitions between excited states of the same parity. At 400 K the measured broadening cross sections are He 115(12) Å2, Ne 120(12) Å2, Ar 234(23) Å2, Kr 266(27) Å2, and Xe 311(31) Å2. With He as the perturber, the cross section for broadening of the 3P12-3P32 transition can be calculated from measured depolarization and fine-structure-changing collision cross sections. With the other perturbers, however, collisional phase changes appear to be important. An intuitive diagrammatic technique for the analysis of echoes is applied to the IDF trilevel echo.

Air-broadened Lorentz halfwidths and pressure-induced line shifts in the nu(4) band of C-13H4

NASA Technical Reports Server (NTRS)

Devi, V. Malathy; Benner, D. Chris; Rinsland, Curtis P.; Smith, Mary Ann H.

1988-01-01

Air-broadened halfwidths and pressure-induced line shifts in the nu(4) fundamental of C-13H4 were determined from spectra recorded at room temperature and at 0.01/cm resolution using a Fourier transform spectrometer. Halfwidths and pressure shifts were determined for over 180 transitions belonging to J-double prime values of less than or = to 16. Comparisons of air-broadened halfwidths and pressure-induced line shifts made for identical transitions in the nu(4) bands of C-12H4 and C-13H4 have shown that C-13H4 air-broadened halfwidths are about 5 percent smaller than the corresponding C-12H4 halfwidths, and the pressure shifts for C-13H4 lines are about 5-15 percent larger than those for C-12H4.

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…

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

Music-induced positive mood broadens the scope of auditory attention.

PubMed

Putkinen, Vesa; Makkonen, Tommi; Eerola, Tuomas

2017-07-01

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. © The Author (2017). Published by Oxford University Press.

High-resolution synchrotron x-ray powder diffraction study of the incommensurate modulation in the martensite phase of Ni2MnGa: Evidence for nearly 7M modulation and phason broadening

NASA Astrophysics Data System (ADS)

Singh, Sanjay; Petricek, V.; Rajput, Parasmani; Hill, Adrian H.; Suard, E.; Barman, S. R.; Pandey, Dhananjai

2014-07-01

The modulated structure of the martensite phase of Ni2MnGa is revisited using high-resolution synchrotron x-ray powder diffraction measurements, which reveal higher-order satellite reflections up to the third order and phason broadening of the satellite peaks. The structure refinement, using the (3+1) dimensional superspace group approach, shows that the modulated structure of Ni2MnGa can be described by orthorhombic superspace group Immm(00γ)s00 with lattice parameters a=4.218 61(2)Å,b=5.546 96(3)Å, and c=4.187 63(2) Å, and an incommensurate modulation wave vector q =0.43160(3)c*=(3/7+δ)c*, where δ =0.00303(3) is the degree of incommensuration of the modulated structure. Additional satellite peak broadening, which could not be accounted for in terms of the anisotropic strain broadening based on a lattice parameter distribution, has been modeled in terms of phasons using fourth-rank covariant strain-tensor representation for incommensurate structures. The simulation of single-crystal diffraction patterns from the refined structural parameters unambiguously reveals a rational approximant structure with 7M modulation. The inhomogeneous displacement of different atomic sites on account of incommensurate modulation and the presence of phason broadening clearly rule out the adaptive phase model proposed recently by Kaufmann et al. [S. Kaufmann, U. K. Rößler, O. Heczko, M. Wuttig, J. Buschbeck, L. Schultz, and S. Fähler, Phys. Rev. Lett. 104, 145702 (2010), 10.1103/PhysRevLett.104.145702] and suggest that the modulation in Ni2MnGa originates from soft-mode phonons.

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.

Vibrational Dependence of Line Coupling and Line Mixing in Self-Broadened Parallel Bands of NH3

NASA Technical Reports Server (NTRS)

Ma, Q.; Boulet, C.; Tipping, R. H.

2017-01-01

Line coupling and line mixing effects have been calculated for several self-broadened NH3 lines in parallel bands involving an excited v2 mode. It is well known that once the v2 mode is excited, the inversion splitting quickly increases as this quantum number increases. In the present study, we have shown that the v2 dependence of the inversion splitting plays a dominant role in the calculated line-shape parameters. For the v2 band with a 36 cm-1 splitting, the intra-doublet couplings practically disappear and for the 2v2 and 2v2 - v2 bands with much higher splitting values, they are completely absent. With respect to the inter-doublet coupling, it becomes the most efficient coupling mechanism for the v2 band, but it is also completely absent for bands with higher v2 quantum numbers. Because line mixing is caused by line coupling, the above conclusions on line coupling are also applicable for line mixing. Concerning the check of our calculated line mixing effects, while the present formalism has well explained the line mixing signatures observed in the v1 band, there are large discrepancies between the measured Rosenkranz mixing parameters and our calculated results for the v2 and 2v2 bands. In order to clarify these discrepancies, we propose to make some new measurements. In addition, we have calculated self-broadened half-widths in the v2 and 2v2 bands and made comparisons with several measurements and with the values listed in HITRAN 2012. In general, the agreements with measurements are very good. In contrast, the agreement with HITRAN 2012 is poor, indicating that the empirical formula used to predict the HITRAN 2012 data has to be updated.

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.

Positron annihilation lifetime and Doppler broadening spectroscopy at the ELBE facility

NASA Astrophysics Data System (ADS)

Wagner, Andreas; Butterling, Maik; Liedke, Maciej O.; Potzger, Kay; Krause-Rehberg, Reinhard

2018-05-01

The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA with bunch charges up to 120 pC. The electron beam is employed to produce several secondary beams including X-rays from bremsstrahlung production, coherent IR light in a Free Electron Laser, superradiant THz radiation, neutrons, and positrons. The secondary positron beam after moderation feeds the Monoenergetic Positron Source (MePS) where positron annihilation lifetime (PALS) and positron annihilation Doppler-broadening experiments in materials science are performed. The adjustable repetition rate of the continuous-wave electron beams allows matching of the pulse separation to the positron lifetime in the sample under study. The energy of the positron beam can be set between 0.5 keV and 20 keV to perform depth resolved defect spectroscopy and porosity studies especially for thin films. Bulk materials, fluids, gases, and even radioactive samples can be studied at the unique Gamma-induced Positron Source (GiPS) where an intense bremsstrahlung source generates positrons directly inside the material under study. A 22Na-based monoenergetic positron beam serves for offline experiments and additional depth-resolved Doppler-broadening studies complementing both accelerator-based sources.

Measurements and calculations of H2-broadening and shift parameters of water vapour transitions of the ν1 + ν2 + ν3 band

NASA Astrophysics Data System (ADS)

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

2018-05-01

The water vapour line broadening and shifting for 97 lines in the ν1 + ν2 + ν3 band induced by hydrogen pressure are measured with Bruker IFS 125 HR FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm-1 and in a wide pressure range of H2. The calculations of the broadening γ and shift δ coefficients were performed in the semi-classical method framework with use of an effective vibrationally depended interaction potential. Two potential parameters were optimised to improve the quality of calculations. Good agreements with measured broadening coefficients were achieved. The comparison of calculated broadening coefficients γ with the previous measurements is discussed. The analytical expressions that reproduce these coefficients for rotational, ν2, ν1, and ν3 vibrational bands are presented.

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.

Saturation Dip Measurements of High-J Transitions in the v_1+v_3 Band of C_2H_2: Absolute Frequencies and Self-Broadening

NASA Astrophysics Data System (ADS)

Sears, Trevor; Twagirayezu, Sylvestre; Hall, Gregory

2017-06-01

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

Self- and Air-Broadened Line Shapes in the 2v3 P and R Branches of 12CH4

NASA Technical Reports Server (NTRS)

Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Crawford, Timothy J.; Yu, Shanshan; Brown, Linda R.; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed

2015-01-01

In this paper we report line shape parameters of 12CH4 for several hundred 2V(sub 3) transitions in the spectral regions 5891-5996 cm( exp -1) (P branch) and 6015-6115 cm(exp -1) (R branch). Air- and self-broadening coefficients were measured as a function of temperature; line mixing via off-diagonal relaxation matrix element coefficients was also obtained for 47 transition pairs. In total, nearly 1517 positions and intensities were retrieved, but many transitions were too weak for the line shape study. For this analysis, we used 25 high-resolution (0.0056 and 0.0067 cm(ex[ -1) and high signal-to-noise (S/N) spectra of high-purity 12CH4 and the same high-purity 12CH4 broadened by dry air recorded at different sample temperatures between 130 K and 295 K with the Bruker IFS 125HR Fourier transform spectrometer at JPL. Three different absorption cells were used (1) a White cell set to a path length of 13.09 m for room temperature data, (2) a single-pass 0.2038 m long coolable cell (for self-broadening) and (3) a multipass cell with 20.941 m total path coolable Herriott cell (for air-broadening). In total there were 13 spectra with pure 12CH4 (0.27-599 Torr) and 12 air-broadened spectra with total sample pressures of 80-805 Torr and volume mixing ratios (VMR) of methane between 0.18 and 1.0. An interactive multispectrum nonlinear least-squares technique was employed to fit the individual P10-P1 and R0-R10 manifolds in all the spectra simultaneously. Results obtained from the present analysis are compared to other recent measurements.

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

PubMed

Hannemann, Sandro; Wu, GuoRong; van Duijn, Eric-Jan; Ubachs, Wim; Cosby, Philip C

2005-11-01

Both laser-induced fluorescence and cavity ring-down spectral observations were made in the Schumann-Runge band system of oxygen, using a novel-type ultranarrow deep-UV pulsed laser source. From measurements on the very weak (0,0) band pressure broadening, pressure shift, and predissociation line-broadening parameters were determined for the B 3sigma(u)-, v = 0,F(i) fine-structure components for various rotational levels in O2. The information content from these studies was combined with that of entirely independent measurements probing the much stronger (0,10), (0,19), and (0,20) Schumann-Runge bands involving preparation of vibrationally excited O2 molecules via photolysis of ozone. The investigations result in a consistent set of predissociation widths for the B 3sigma(u)-, v = 0 state of oxygen.

Solitary waves of surface plasmon polariton via phase shifts under Doppler broadening and Kerr nonlinearity

NASA Astrophysics Data System (ADS)

Ahmad, S.; Ahmad, A.; Bacha, B. A.; Khan, A. A.; Abdul Jabar, M. S.

2017-12-01

Surface Plasmon Polaritons (SPPs) are theoretically investigated at the interface of a dielectric metal and gold. The output pulse from the dielectric is used as the input pulse for the generation of SPPs. The SPPs show soliton-like behavior at the interface. The solitary form of a SPP is maintained under the effects of Kerr nonlinearity, Doppler broadening and Fresnel dragging whereas its phase shift is significantly modified. A 0.3radian phase shift is calculated in the presence of both Kerr nonlinearity and Fresnel dragging in the absence of plasma motion. The phase shift is enhanced to 60radian due to the combined effect of Doppler broadening, Kerr nonlinearity and Fresnel dragging. The results may have significant applications in nano-photonics, optical tweezers, photovoltaic devices, plasmonster and sensing technology.

From forensic epigenetics to forensic epigenomics: broadening DNA investigative intelligence.

PubMed

Vidaki, Athina; Kayser, Manfred

2017-12-21

Human genetic variation is a major resource in forensics, but does not allow all forensically relevant questions to be answered. Some questions may instead be addressable via epigenomics, as the epigenome acts as an interphase between the fixed genome and the dynamic environment. We envision future forensic applications of DNA methylation analysis that will broaden DNA-based forensic intelligence. Together with genetic prediction of appearance and biogeographic ancestry, epigenomic lifestyle prediction is expected to increase the ability of police to find unknown perpetrators of crime who are not identifiable using current forensic DNA profiling.

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.

Collisional Broadening and Shift of D1 and D2 Spectral Lines in Atomic Alkali Vapor - Noble Gas Systems

DTIC Science & Technology

2013-03-01

12 curve fit to the 2Σ1 2� − 2Σ1 2� difference potential Table 2.2a: Lennard - Jones parameters for Rubidium + Helium lines. Difference...Table Page Table 2.2a. Lennard - Jones parameters for Rubidium + Helium lines 22 Table 2.2b. Line broadening and shift parameters for Rb + He lines...all nine M + Ng pairs, using Lennard - Jones (6-12) potentials in Anderson- Talman 25 Table 2.2e. Broadening and shift coefficients (in MHz/torr

CARRIER-LATTICE RELAXATION FOR BROADENING EPR LINEWIDTH IN Nd0.55Sr0.45MnO3

NASA Astrophysics Data System (ADS)

Fan, Jiyu; Zhang, Xiyuan; Tong, Wei; Zhang, Lei; Zhang, Weichun; Zhu, Yan; Shi, Yangguang; Hu, Dazhi; Hong, Bo; Ying, Yao; Ling, Langsheng; Pi, Li; Zhang, Yuheng

2013-12-01

In this paper, we report the electron paramagnetic resonance (EPR) study of perovskite manganite Nd0.55Sr0.45MnO3. Experimental data reveal that the EPR linewidth broadens with a quasilinear manner up to 480 K. The broadening of the EPR linewidth can be understood in terms of the shortening of carrier-lattice relaxation time due to the occurrence of strong carrier-phonon interactions. Two same activation energies obtained respectively from the temperature dependence of EPR intensity and resistivity indicate that the linewidth variation is correlated to the small polaron hopping. Therefore, the carrier-lattice coupling play a major role for deciding its magnetism in the present system.

Doppler-Broadening Gas Thermometry at 1.39 μm: Towards a New Spectroscopic Determination of the Boltzmann Constant

NASA Astrophysics Data System (ADS)

Castrillo, A.; de Vizia, M. D.; Fasci, E.; Odintsova, T.; Moretti, L.; Gianfrani, L.

The expression of the Doppler width of a spectral line, valid for a gaseous sample at thermodynamic equilibrium, represents a powerful tool to link the thermodynamic temperature to an optical frequency. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry. Implemented at the Second University of Naples on H218O molecules at the temperature of the triple point of water, this method has recently allowed to determine the Boltzmann constant with a global uncertainty of 24 parts over 106. Even though this is the best result ever obtained by using an optical method, its uncertainty is still far from the requirement for the new definition of the unit kelvin. To this end, Doppler broadening thermometry should approach the accuracy of 1 part per million. In this paper, we will report on our recent efforts to further develop and optimize Doppler broadening thermometry at 1.39 μm, using acetylene as a molecular target. Main progresses and current limitations will be highlighted.

Simultaneous influence of Stark effect and excessive line broadening on the Hα line

NASA Astrophysics Data System (ADS)

Cvetanović, Nikola; Ivković, Saša S.; Obradović, Bratislav M.; Kuraica, Milorad M.

2017-12-01

The aim of this paper is to study the combined influence of the Stark effect and the excessive Doppler broadening on the Balmer alpha line in hydrogen discharges. Since this line is a good candidate for measuring electric field in various types of discharges with different gas compositions, a simple method for field measurement based on polarization spectroscopy is developed, that includes all the excitation mechanisms. To simultaneously test the flexibility of the fitting procedure and investigate the excessive broadening, we applied the fitting procedure on line profiles obtained at a range of conditions from two different discharges. The range of pressures and voltages was examined in an abnormal glow and in dielectric barrier discharge operating with hydrogen gas. The model fitting function was able to respond and follow the change in the line profile caused by the change of conditions. This procedure can therefore be recommended for electric field measurement. Contribution to the "Topical Issue: Physics of Ionized Gases (SPIG 2016)", edited by Goran Poparic, Bratislav Obradovic, Dragana Maric and Aleksandar Milosavljevic.

Quasiparticle Lifetime Broadening in Resonant X-ray Scattering of NH4NO3.

PubMed

Vinson, John; Jach, Terrence; Müller, Matthias; Unterumsberger, Rainer; Beckhoff, Burkhard

2016-07-15

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.

The assembly of ant-farmed gardens: mutualism specialization following host broadening

PubMed Central

Janda, Milan

2017-01-01

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. PMID:28298344

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.

Practical Model for First Hyperpolarizability Dispersion Accounting for Both Homogeneous and Inhomogeneous Broadening Effects.

PubMed

Campo, Jochen; Wenseleers, Wim; Hales, Joel M; Makarov, Nikolay S; Perry, Joseph W

2012-08-16

A practical yet accurate dispersion model for the molecular first hyperpolarizability β is presented, incorporating both homogeneous and inhomogeneous line broadening because these affect the β dispersion differently, even if they are indistinguishable in linear absorption. Consequently, combining the absorption spectrum with one free shape-determining parameter Ginhom, the inhomogeneous line width, turns out to be necessary and sufficient to obtain a reliable description of the β dispersion, requiring no information on the homogeneous (including vibronic) and inhomogeneous line broadening mechanisms involved, providing an ideal model for practical use in extrapolating experimental nonlinear optical (NLO) data. The model is applied to the efficient NLO chromophore picolinium quinodimethane, yielding an excellent fit of the two-photon resonant wavelength-dependent data and a dependable static value β0 = 316 × 10(-30) esu. Furthermore, we show that including a second electronic excited state in the model does yield an improved description of the NLO data at shorter wavelengths but has only limited influence on β0.

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.

Resonance frequency broadening of wave-particle interaction in tokamaks due to Alfvénic eigenmode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Guo; Gorelenkov, Nikolai N.; Duarte, Vinicius N.

We use the guiding center code ORBIT to study the broadening of resonances and the parametric dependence of the resonance frequency broadening widthmore » $$\\Delta\\Omega$$ on the nonlinear particle trapping frequency $$\\omega_b$$ of wave-particle interaction with specific examples using realistic equilibrium DIII-D shot 159243 (Collins et al. 2016 Phys. Rev. Lett. 116 095001). When the mode amplitude is small, the pendulum approximation for energetic particle dynamics near the resonance is found to be applicable and the ratio of the resonance frequency width to the deeply trapped bounce frequency $$\\Delta\\Omega/\\omega_b$$ equals 4, as predicted by theory. Lastly, it is found that as the mode amplitude increases, the coefficient $$a=\\Delta\\Omega/\\omega_b$$ becomes increasingly smaller because of the breaking down of the nonlinear pendulum approximation for the wave-particle interaction.« less

Resonance frequency broadening of wave-particle interaction in tokamaks due to Alfvénic eigenmode

DOE PAGES

Meng, Guo; Gorelenkov, Nikolai N.; Duarte, Vinicius N.; ...

2018-01-19

We use the guiding center code ORBIT to study the broadening of resonances and the parametric dependence of the resonance frequency broadening widthmore » $$\\Delta\\Omega$$ on the nonlinear particle trapping frequency $$\\omega_b$$ of wave-particle interaction with specific examples using realistic equilibrium DIII-D shot 159243 (Collins et al. 2016 Phys. Rev. Lett. 116 095001). When the mode amplitude is small, the pendulum approximation for energetic particle dynamics near the resonance is found to be applicable and the ratio of the resonance frequency width to the deeply trapped bounce frequency $$\\Delta\\Omega/\\omega_b$$ equals 4, as predicted by theory. Lastly, it is found that as the mode amplitude increases, the coefficient $$a=\\Delta\\Omega/\\omega_b$$ becomes increasingly smaller because of the breaking down of the nonlinear pendulum approximation for the wave-particle interaction.« less

Cavity-ring-down Doppler-broadening primary thermometry

NASA Astrophysics Data System (ADS)

Gotti, Riccardo; Moretti, Luigi; Gatti, Davide; Castrillo, Antonio; Galzerano, Gianluca; Laporta, Paolo; Gianfrani, Livio; Marangoni, Marco

2018-01-01

A step forward in Doppler-broadening thermometry is demonstrated using a comb-assisted cavity-ring-down spectroscopic approach applied to an isolated near-infrared line of carbon dioxide at thermodynamic equilibrium. Specifically, the line-shape of the Pe(12 ) line of the (30012 )←(00001 ) band of C O2 at 1.578 µm is accurately measured and its Doppler width extracted from a refined multispectrum fitting procedure accounting for the speed dependence of the relaxation rates, which were found to play a role even at the very low pressures explored, from 1 to 7 Pa. The thermodynamic gas temperature is retrieved with relative uncertainties of 8 ×10-6 (type A) and 11 ×10-6 (type B), which ranks the system at the first place among optical methods. Thanks to a measurement time of only ≈5 h , the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10-6 level.

Enhancing the resolution of 1H and 13C solid-state NMR spectra by reduction of anisotropic bulk magnetic susceptibility broadening.

PubMed

Hanrahan, Michael P; Venkatesh, Amrit; Carnahan, Scott L; Calahan, Julie L; Lubach, Joseph W; Munson, Eric J; Rossini, Aaron J

2017-10-25

We demonstrate that natural isotopic abundance 2D heteronuclear correlation (HETCOR) solid-state NMR spectra can be used to significantly reduce or eliminate the broadening of 1 H and 13 C solid-state NMR spectra of organic solids due to anisotropic bulk magnetic susceptibility (ABMS). ABMS often manifests in solids with aromatic groups, such as active pharmaceutical ingredients (APIs), and inhomogeneously broadens the NMR peaks of all nuclei in the sample. Inhomogeneous peaks with full widths at half maximum (FWHM) of ∼1 ppm typically result from ABMS broadening and the low spectral resolution impedes the analysis of solid-state NMR spectra. ABMS broadening of solid-state NMR spectra has previously been eliminated using 2D multiple-quantum correlation experiments, or by performing NMR experiments on diluted materials or single crystals. However, these experiments are often infeasible due to their poor sensitivity and/or provide limited gains in resolution. 2D 1 H- 13 C HETCOR experiments have previously been applied to reduce susceptibility broadening in paramagnetic solids and we show that this strategy can significantly reduce ABMS broadening in diamagnetic organic solids. Comparisons of 1D solid-state NMR spectra and 1 H and 13 C solid-state NMR spectra obtained from 2D 1 H- 13 C HETCOR NMR spectra show that the HETCOR spectrum directly increases resolution by a factor of 1.5 to 8. The direct gain in resolution is determined by the ratio of the inhomogeneous 13 C/ 1 H linewidth to the homogeneous 1 H linewidth, with the former depending on the magnitude of the ABMS broadening and the strength of the applied field and the latter on the efficiency of homonuclear decoupling. The direct gains in resolution obtained using the 2D HETCOR experiments are better than that obtained by dilution. For solids with long proton longitudinal relaxation times, dynamic nuclear polarization (DNP) was applied to enhance sensitivity and enable the acquisition of 2D 1 H- 13 C

Broadening of the infrared absorption lines at reduced temperatures. II - Carbon monoxide in an atmosphere of carbon dioxide.

NASA Technical Reports Server (NTRS)

Tubbs, L. D.; Williams, D.

1972-01-01

The strengths of the rotational lines in the R branch of the CO fundamental have been determined at temperatures of 298, 202, and 132 K by means of a high-resolution spectrograph. The results can be used to determine line strengths at other temperatures by means of the Herman-Wallis relation or by considerations of the populations of the rotational levels in the ground vibrational state. Parameters describing the self-broadening and carbon dioxide broadening of CO lines have been determined at 298 and 202 K. The results are compared with other recent experimental and theoretical studies.

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. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Air- and N2-Broadening Coefficients and Pressure-Shift Coefficients in the C-12(O2-16) Laser Bands

NASA Technical Reports Server (NTRS)

Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Rinsland, Curtis P.

1998-01-01

In this paper we report the pressure broadening and the pressure-induced line shift coefficients for 46 individual rovibrational lines in both the (12)C(16)O2, 00(sup 0)1-(10(sup 0)0-02(sup 0)0)I, and 00(sup 0)1-(10(sup 0)0-02(sup 0)0)II, laser bands (laser band I centered at 960.959/cm and laser band II centered at 1063.735/cm) determined from spectra recorded with the McMath-Pierce Fourier transform spectrometer. The results were obtained from analysis of 10 long-path laboratory absorption spectra recorded at room temperature using a multispectrum nonlinear least-squares technique. Pressure effects caused by both air and nitrogen have been investigated. The air-broadening coefficients determined in this study agree well with the values in the 1996 HITRAN database; ratios and standard deviations of the ratios of the present air-broadening measurements to the 1996 HITRAN values for the two laser bands are: 1.005(15) for laser band I and 1.005(14) for laser band II. Broadening by nitrogen is 3 to 4% larger than that of air. The pressure-induced line shift coefficients are found to be transition dependent and different for the P- and R-branch lines with same J" value. No noticeable differences in the shift coefficients caused by air and nitrogen were found. The results obtained are compared with available values previously reported in the literature.

Temperature-Induced Large Broadening and Blue Shift in the Electronic Band Structure and Optical Absorption of Methylammonium Lead Iodide Perovskite.

PubMed

Yang, Jia-Yue; Hu, Ming

2017-08-17

The power conversion efficiency of hybrid halide perovskite solar cells is profoundly influenced by the operating temperature. Here we investigate the temperature influence on the electronic band structure and optical absorption of cubic CH 3 NH 3 PbI 3 from first-principles by accounting for both the electron-phonon interaction and thermal expansion. Within the framework of density functional perturbation theory, the electron-phonon coupling induces slightly enlarged band gap and strongly broadened electronic relaxation time as temperature increases. The large broadening effect is mainly due to the presence of cation organic atoms. Consequently, the temperature-dependent absorption peak exhibits blue-shift position, decreased amplitude, and broadened width. This work uncovers the atomistic origin of temperature influence on the optical absorption of cubic CH 3 NH 3 PbI 3 and can provide guidance to design high-performance hybrid halide perovskite solar cells at different operating temperatures.

Investigation of the collision line broadening problem as applicable to the NASA Optical Plume Anomaly Detection (OPAD) system, phase 1

NASA Astrophysics Data System (ADS)

Dean, Timothy C.; Ventrice, Carl A.

1995-05-01

As a final report for phase 1 of the project, the researchers are submitting to the Tennessee Tech Office of Research the following two papers (reprinted in this report): 'Collision Line Broadening Effects on Spectrometric Data from the Optical Plume Anomaly System (OPAD),' presented at the 30th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 27-29 June 1994, and 'Calculation of Collision Cross Sections for Atomic Line Broadening in the Plume of the Space Shuttle Main Engine (SSME),' presented at the IEEE Southeastcon '95, 26-29 March 1995. These papers fully state the problem and the progress made up to the end of NASA Fiscal Year 1994. The NASA OPAD system was devised to predict concentrations of anomalous species in the plume of the Space Shuttle Main Engine (SSME) through analysis of spectrometric data. The self absorption of the radiation of these plume anomalies is highly dependent on the line shape of the atomic transition of interest. The Collision Line Broadening paper discusses the methods used to predict line shapes of atomic transitions in the environment of a rocket plume. The Voigt profile is used as the line shape factor since both Doppler and collisional line broadening are significant. Methods used to determine the collisional cross sections are discussed and the results are given and compared with experimental data. These collisional cross sections are then incorporated into the current self absorbing radiative model and the predicted spectrum is compared to actual spectral data collected from the Stennis Space Center Diagnostic Test Facility rocket engine. The second paper included in this report investigates an analytical method for determining the cross sections for collision line broadening by molecular perturbers, using effective central force interaction potentials. These cross sections are determined for several atomic species with H2, one of the principal constituents of the SSME plume environment, and compared with experimental data.

Temperature dependence of the pressure broadening of spectral lines

NASA Astrophysics Data System (ADS)

Roston, G. D.; Helmi, M. S.

2012-12-01

The aim of this work is to obtain a formula relating the pressure broadening coefficient of the spectral line β with the temperature T, when the difference potential ΔV(R) between the upper and lower states of the emitting atom is represented by (Lennard - Jones) potential, The obtained formula is a power index law of β on T. This formula is applied for calculating β for different interactions of Ar, Ne, TI, Hg, Cd and Zn with the inert gases (Xe, Kr, Ar, Ne and He) at different temperatures. The results of these calculations are in good agreement with the corresponding values obtained before numerically. The obtained formula is considered very important in astrophysical problems.

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

Line mixing in a N2-broadened CO2 Q branch observed with a tunable diode laser

NASA Technical Reports Server (NTRS)

Gentry, Bruce; Strow, L. Larrabee

1987-01-01

Line-mixing effects have been observed in the infrared Q branch of the (11/1/0,03/1/0)I-00/0/0 band of CO2 at 2076/cm. A tunable diode laser spectrometer was used to record spectra of CO2 broadened by N2 and O2 at total pressures ranging from 100 to 720 torr. The observed absorption coefficients are up to 65 percent lower than those calculated using an isolated Lorentzian line approximation. A simple energy gap scaling law is used to determine the off-diagonal relaxation matrix elements from the known pressure-broadening coefficients. The spectra calculated using these matrix elements reproduces the observed absorption coefficients to within several percent.

Speed dependence of CH335Cl-O2 line-broadening parameters probed on rotational transitions: Measurements and semi-classical calculations

NASA Astrophysics Data System (ADS)

Buldyreva, J.; Margulès, L.; Motiyenko, R. A.; Rohart, F.

2013-11-01

Relaxation parameters for K-components (K≤6) of six J→J+1 rotational transitions (J=6, 10, 17, 22, 31 and 33) of CH335Cl perturbed by O2 are measured at room temperature with Voigt, speed-dependent Voigt and Galatry profiles in order to probe the speed-dependence effects. With respect to the previous study of CH335Cl-N2 system [Guinet et al., J Quant Spectrosc Radiat Transfer 2012;113:1113], higher active-gas pressures are reached, providing better signal-to-noise ratios, and the exact expression of the Beer-Lambert law is introduced in the fitting procedure, leading, among other advantages, to much more realistic low-pressure results. The broadening parameters of the considered lines are also computed by a semi-classical method for various relative velocities of colliders and the powers characterizing the dependence of the collisional cross-sections on relative speeds are deduced as functions of the rotational numbers J and K. Additional calculations performed with the Maxwell-Boltzmann distribution of velocities show no significant difference with the earlier results [Buldyreva et al., Phys Chem Chem Phys 2011;13:20326] obtained within the mean thermal velocity approximation. Weighted sums of the presently measured Voigt-profile O2-broadening parameters and of the previously published N2-broadening ones are calculated to yield experimental air-broadening coefficients for spectroscopic databases.

Effects of tenotomy on patients with infantile nystagmus syndrome: foveation improvement over a broadened visual field.

PubMed

Wang, Zhong; Dell'Osso, Louis F; Jacobs, Jonathan B; Burnstine, Robert A; Tomsak, Robert L

2006-12-01

To investigate the effects of four-muscle tenotomy on visual function and gaze angle in patients with infantile nystagmus syndrome (INS). Eye movements of nine patients with infantile nystagmus were recorded using infrared reflection or high-speed digital video techniques. Experimental protocols were designed to record the patients' eye-movement waveforms, pre- and post-tenotomy, at different gaze angles. We used the eXpanded Nystagmus Acuity Function (NAFX) to measure tenotomy-induced changes in the nystagmus at primary position and various gaze angles. The longest foveation domains (LFD) were measured from fitted curves. Peak-to-peak nystagmus amplitudes and foveation-period durations were also measured. All measurements were made unmasked. All seven patients with narrow, high-NAFX, gaze-angle regions showed broadening of these regions of higher visual function. Three patients showed moderate NAFX improvement (13.9-32.6%) at primary position, five showed large improvement (39.9-162.4%), and one showed no NAFX change (due to his high pretenotomy NAFX). Primary position measured acuities improved in six patients. All patients had reductions in nystagmus amplitudes ranging from 14.6 to 37%. The duration of the foveation period increased in all nine patients (11.2-200%). The percentage improvements in both the NAFX and the LFD decreased with higher pretenotomy values. In addition to elevating primary position NAFX, tenotomy also broadens the high-NAFX regions. This broadening effect is more prominent in patients who had sharp pretenotomy NAFX peaks. Four-muscle tenotomy produces higher primary position NAFX increases in infantile nystagmus patients whose pretenotomy values are relatively low, with the improvement decreasing at higher pretenotomy values. The tenotomy procedure improves visual function beyond primary position acuity. This extends the utility of surgical therapy to several different classes of patients with INS for whom other procedures are

The Influence of Beam Broadening on the Spatial Resolution of Annular Dark Field Scanning Transmission Electron Microscopy.

PubMed

de Jonge, Niels; Verch, Andreas; Demers, Hendrix

2018-02-01

The spatial resolution of aberration-corrected annular dark field scanning transmission electron microscopy was studied as function of the vertical position z within a sample. The samples consisted of gold nanoparticles (AuNPs) positioned in different horizontal layers within aluminum matrices of 0.6 and 1.0 µm thickness. The highest resolution was achieved in the top layer, whereas the resolution was reduced by beam broadening for AuNPs deeper in the sample. To examine the influence of the beam broadening, the intensity profiles of line scans over nanoparticles at a certain vertical location were analyzed. The experimental data were compared with Monte Carlo simulations that accurately matched the data. The spatial resolution was also calculated using three different theoretical models of the beam blurring as function of the vertical position within the sample. One model considered beam blurring to occur as a single scattering event but was found to be inaccurate for larger depths of the AuNPs in the sample. Two models were adapted and evaluated that include estimates for multiple scattering, and these described the data with sufficient accuracy to be able to predict the resolution. The beam broadening depended on z 1.5 in all three models.

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.

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.

Laser-based measurements of pressure broadening and pressure shift coefficients of combustion-relevant absorption lines in the near-infrared region

NASA Astrophysics Data System (ADS)

Bürkle, Sebastian; Walter, Nicole; Wagner, Steven

2018-06-01

A set of high-resolution absorption spectrometers based on TDLAS was used to determine the impact of combustion-relevant gases on the pressure shift and broadening of H2O, CO2, C2H2 and CH4 absorption lines in the near-infrared spectral region. In particular, self- and foreign-broadening coefficients induced by CO2, N2, O2, air, C2H2 and CH4 were measured. The absorption lines under investigation are suitable to measure the respective species in typical combustion environments via laser absorption spectroscopy. Additionally, species-dependent self- and foreign-induced pressure shift coefficients were measured and compared to the literature. The experiments were performed in two specifically designed absorption cells over a wide pressure range from 5 to 180 kPa. Different sources of uncertainty were identified and quantified to achieve relative measurement uncertainties of 0.7-1.5% for broadening coefficients and 0.6-1.6% for pressure shift coefficients.

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.

Quasiparticle lifetime broadening in resonant x-ray scattering of NH4NO3

NASA Astrophysics Data System (ADS)

Vinson, John; Jach, Terrence; Müller, Matthias; Unterumsberger, Rainer; Beckhoff, Burkhard

2016-07-01

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 the 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 G W /Bethe-Salpeter approach, we show the extent to which this anomalous broadening is captured by the G W approximation. The data and calculations demonstrate the importance that the complex self-energies (finite lifetimes) of the 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.

Upward Spirals of Positive Emotions Counter Downward Spirals of Negativity: Insights from the Broaden-and-Build Theory and Affective Neuroscience on The Treatment of Emotion Dysfunctions and Deficits in Psychopathology

PubMed Central

Garland, Eric L.; Fredrickson, Barbara; Kring, Ann M.; Johnson, David P.; Meyer, Piper S.; Penn, David L.

2010-01-01

This review integrates Fredrickson’s broaden-and-build theory of positive emotions with advances in affective neuroscience regarding plasticity in the neural circuitry of emotions to inform the treatment of emotion deficits within psychopathology. We first present a body of research showing that positive emotions broaden cognition and behavioral repertoires, and in so doing, build durable biopsychosocial resources that support coping and flourishing mental health. Next, by explicating the processes through which momentary experiences of emotions may accrue into self-perpetuating emotional systems, the current review proposes an underlying architecture of state-trait interactions that engenders lasting affective dispositions. This theoretical framework is then used to elucidate the cognitive-emotional mechanisms underpinning three disorders of affect regulation, depression, anxiety, and schizophrenia. In turn, two mind training interventions, mindfulness and loving-kindness meditation, are highlighted as means of generating positive emotions that may counter the negative affective processes implicated in these disorders. We conclude with the proposition that positive emotions may exert a countervailing force on the dysphoric, fearful, or anhedonic states characteristic of persons with psychopathology typified by emotional dysfunctions. PMID:20363063

High-resolution Fourier transform measurements of air-induced broadening and shift coefficients in the 0002-0000 main isotopologue band of nitrous oxide

NASA Astrophysics Data System (ADS)

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

2018-06-01

In the present study, we report highly accurate air-induced broadening and shift coefficients for the nitrous oxide (N2O) 0002-0000 band at 2.26 μm of the main isotopologue retrieved from high-resolution Fourier transform infrared (FTIR) measurements with metrologically determined pressure, temperature, absorption path length and chemical composition. Most of our retrieved air-broadening coefficients agree with previously generated datasets within the expanded (confidence interval of 95%) uncertainties. For the air-shift coefficients our results suggest a different rotational dependence compared to literature. The present study benefits from improved measurement conditions and a detailed metrological uncertainty description. Comparing to literature, the uncertainties of the previous broadening and shift coefficients are improved by a factor of up to 39 and up to 22, respectively.

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).

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.

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.

Does positive affect broaden and negative affect narrow attentional scope? A new answer to an old question.

PubMed

Huntsinger, Jeffrey R

2012-11-01

The current research challenges the common view that positive affect and negative affect generate a broadened or narrowed attentional focus, respectively. Contrary to this view, two studies found that the link between affect and attentional focus as measured by a traditional flanker task (Study 1) and a modified flanker task (Study 2) reflects whatever focus is momentarily dominant. Further, in these studies when neither focus was dominant, the link between affect and attentional focus vanished. These results demonstrate that, like reward, positive affect and negative affect are not dedicated to a particular broadened or narrowed attentional scope but rather provide embodied information about the value of currently accessible attentional orientations. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Electron-beam broadening in amorphous carbon films in low-energy scanning transmission electron microscopy.

PubMed

Drees, H; Müller, E; Dries, M; Gerthsen, D

2018-02-01

Resolution in scanning transmission electron microscopy (STEM) is ultimately limited by the diameter of the electron beam. The electron beam diameter is not only determined by the properties of the condenser lens system but also by electron scattering in the specimen which leads to electron-beam broadening and degradation of the resolution with increasing specimen thickness. In this work we introduce a new method to measure electron-beam broadening which is based on STEM imaging with a multi-segmented STEM detector. We focus on STEM at low electron energies between 10 and 30 keV and use an amorphous carbon film with known thickness as test object. The experimental results are compared with calculated beam diameters using different analytical models and Monte-Carlo simulations. We find excellent agreement of the experimental data with the recently published model by Gauvin and Rudinsky [1] for small t/λ el (thickness to elastic mean free path) values which are considered in our study. Copyright © 2017 Elsevier B.V. All rights reserved.

Achieving high peak capacity production for gas chromatography and comprehensive two-dimensional gas chromatography by minimizing off-column peak broadening.

PubMed

Wilson, Ryan B; Siegler, W Christopher; Hoggard, Jamin C; Fitz, Brian D; Nadeau, Jeremy S; Synovec, Robert E

2011-05-27

By taking into consideration band broadening theory and using those results to select experimental conditions, and also by reducing the injection pulse width, peak capacity production (i.e., peak capacity per separation time) is substantially improved for one dimensional (1D-GC) and comprehensive two dimensional (GC×GC) gas chromatography. A theoretical framework for determining the optimal linear gas velocity (the linear gas velocity producing the minimum H), from experimental parameters provides an in-depth understanding of the potential for GC separations in the absence of extra-column band broadening. The extra-column band broadening is referred to herein as off-column band broadening since it is additional band broadening not due to the on-column separation processes. The theory provides the basis to experimentally evaluate and improve temperature programmed 1D-GC separations, but in order to do so with a commercial 1D-GC instrument platform, off-column band broadening from injection and detection needed to be significantly reduced. Specifically for injection, a resistively heated transfer line is coupled to a high-speed diaphragm valve to provide a suitable injection pulse width (referred to herein as modified injection). Additionally, flame ionization detection (FID) was modified to provide a data collection rate of 5kHz. The use of long, relatively narrow open tubular capillary columns and a 40°C/min programming rate were explored for 1D-GC, specifically a 40m, 180μm i.d. capillary column operated at or above the optimal average linear gas velocity. Injection using standard auto-injection with a 1:400 split resulted in an average peak width of ∼1.5s, hence a peak capacity production of 40peaks/min. In contrast, use of modified injection produced ∼500ms peak widths for 1D-GC, i.e., a peak capacity production of 120peaks/min (a 3-fold improvement over standard auto-injection). Implementation of modified injection resulted in retention time, peak width

Latitudinal variation of speed and mass flux in the acceleration region of the solar wind inferred from spectral broadening measurements

NASA Technical Reports Server (NTRS)

Woo, Richard; Goldstein, Richard M.

1994-01-01

Spectral broadening measurements conducted at S-band (13-cm wavelength) during solar minimum conditions in the heliocentric distance range of 3-8 R(sub O) by Mariner 4, Pioneer 10, Mariner 10, Helios 1, Helios 2, and Viking have been combined to reveal a factor of 2.6 reduction in bandwidth from equator to pole. Since spectral broadening bandwidth depends on electron density fluctuation and solar wind speed, and latitudinal variation of the former is available from coherence bandwidth measurements, the remote sensing spectral broadening measurements provide the first determination of the latitudinal variation of solar wind speed in the acceleration region. When combined with electron density measurements deduced from white-light coronagraphs, this result also leads to the first determination of the latitudinal variation of mass flux in the acceleration region. From equator to pole, solar wind speed increases by a factor of 2.2, while mass flux decreases by a factor of 2.3. These results are consistent with measurements of solar wind speed by multi-station intensity scintillation measurements, as well as measurements of mass flux inferred from Lyman alpha observations, both of which pertain to the solar wind beyond 0.5 AU. The spectral broadening observations, therefore, strengthen earlier conclusions about the latitudinal variation of solar wind speed and mass flux, and reinforce current solar coronal models and their implications for solar wind acceleration and solar wind modeling.

Gain anisotropy and simultaneous bidirectional emission of a Doppler-broadened MIR optically-pumped ammonia ring laser

NASA Astrophysics Data System (ADS)

Wazen, P.; Bourdet, G. L.

1991-01-01

The authors studied the Doppler-broadened 11.76-micron N-15H3 emission line optically pumped in a ring resonator by a CW CO2 laser operating on the 10R(42) line. Behavior related to the optical pumping of gas Doppler-broadened lines is found and shown to be very dependent on the laser parameters. For instance, the laser emission can occur in one direction or two directions simultaneously. A local gain model based on the interaction of two laser fields with a three-level molecular system is used to clarify the emission characteristics of this laser. Basically, the two-photon or Raman process and the Rabi splitting generate a gain anisotropy and an anomalous dispersion curve. The effects lead to a different optical path for the two directions of propagation and, consequently, a simultaneous bidirectional emission with unequal emission frequency.

ELM-free and inter-ELM divertor heat flux broadening induced by edge harmonics oscillation in NSTX

DOE PAGES

Gan, K. F.; Ahn, J. -W.; Gray, T. K.; ...

2017-10-26

A new n =1 dominated edge harmonic oscillation (EHO) has been found in NSTX. The new EHO, rotating toroidally in the counter-current direction and the opposite direction of the neutral beam, was observed during certain inter-ELM and ELM-free periods of H-mode operation. This EHO is associated with a significant broadening of the integral heat flux width (more » $${{\\lambda}_{\\operatorname{int}}}$$ ) by up to 150%, and a decrease in the divertor peak heat flux by >60%. An EHO induced filament was also observed by the gas puff imaging diagnostic. The toroidal rotating filaments could change the edge magnetic topology resulting in toroidal rotating strike point splitting and heat flux broadening. Finally, experimental result of the counter current rotation of strike points splitting is consistent with the counter-current EHO.« less

(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.

Broadening of the divertor heat flux footprint with increasing number of ELM filaments in NSTX

NASA Astrophysics Data System (ADS)

Ahn, Joon-Wook

2014-10-01

We report on the broadening (narrowing) of the ELM heat flux footprint with increasing (decreasing) number of filamentary striations from in-depth thermography measurements in NSTX. Edge localized modes (ELMs) represent a challenge to future fusion devices, due to the high heat fluxes on plasma facing surfaces. One ameliorating factor has been that the divertor heat flux characteristic profile width (λq) has been observed to broaden with the size of ELM, as compared with the inter-ELM λq, which keeps the peak heat flux (qpeak) from increasing. In contrast, λq has been observed to narrow during ELMs under certain conditions in NSTX, for both naturally occurring and 3-D fields triggered ELMs. Fast thermographic measurements and detailed analysis demonstrate that the ELM λq increases with the number of observed filamentary striations, i . e . , profile narrowing (broadening) occurs when the number of striations is smaller (larger) than 3-4. With profile narrowing, qpeak at ELM peak times is inversely related (proportional) to λq (the ELM size), exacerbating the heat flux problem. Edge stability analysis shows that NSTX ELMs almost always lie on the current-driven kink/peeling mode side with low toroidal mode number (n = 1--5), consistent with the typical numbers of striations in NSTX (0-8) in comparison 10--15 striations are normally observed in intermediate-n peeling-ballooning ELMs, e.g., from JET. The NSTX characteristics may translate directly to ITER, which is also projected to lie on the low-n kink/peeling stability boundary. This work was supported by the U.S. DOE, Contract DE-AC05-00OR22725 (ORNL) and DE-AC02-09CH11466 (PPPL).

Composition-dependent emission linewidth broadening in lead bromide perovskite (APbBr3, A = Cs and CH3NH3) nanoparticles.

PubMed

Ham, Sujin; Chung, Heejae; Kim, Tae-Woo; Kim, Jiwon; Kim, Dongho

2018-02-01

Lead halide perovskite nanoparticles (NPs) are attractive as they exhibit excellent color purity and have a tunable band gap, and can thus be applied in highly efficient photovoltaic and light-emitting diodes. Fundamental studies of emission linewidth broadening due to spectral shifts in perovskite NPs may suggest a way to improve their color purity. However, the carrier-induced Stark shift that causes spectral diffusion still requires investigation. In this study, we explore composition-related emission linewidth broadening by comparing CsPbBr3 and CH 3 NH 3 PbBr 3 (MAPbBr3) perovskite NPs. We find that the MAPbBr3 NPs are more sensitive to fluctuations in the local electric fields than the CsPbBr3 NPs due to an intrinsic difference in the dipole moment between the two A cations (Cs and MA), which shows a carrier-induced Stark shift. The results indicate that the compositions of perovskite NPs are closely associated with emission linewidth broadening and they also provide insights into the development of NP-based devices with high color purity.

The importance of system band broadening in modern size exclusion chromatography.

PubMed

Goyon, Alexandre; Guillarme, Davy; Fekete, Szabolcs

2017-02-20

In the last few years, highly efficient UHP-SEC columns packed with sub-3μm particles were commercialized by several providers. Besides the particle size reduction, the dimensions of modern SEC stationary phases (150×4.6mm) was also modified compared to regular SEC columns (300×6 or 300×8mm). Because the analytes are excluded from the pores in SEC, the retention factors are very low, ranging from -1 broadening, the apparent efficiency of SEC columns packed with sub-2μm particles can indeed be hampered when using inappropriate system. Considering the extra-column band broadening contribution of current UHPLC instruments, a further decrease of SEC column dimension is therefore not desired. Copyright © 2016 Elsevier B.V. All rights reserved.

Temperature-Dependence of Air-Broadened Line Widths and Shifts in the nu3 Band of Ozone

NASA Technical Reports Server (NTRS)

Smith, Mary A. H.; Rinsland, Curtis P.; Devi, V. Malathy; Benner, D. Chris; Cox, A. M.

2006-01-01

The 9.6-micron bands of O3 are used by many remote-sensing experiments for retrievals of terrestrial atmospheric ozone concentration profiles. Line parameter errors can contribute significantly to the total errors in these retrievals, particularly for nadir-viewing. The McMath-Pierce Fourier transform spectrometer at the National Solar Observatory on Kitt Peak was used to record numerous high-resolution infrared absorption spectra of O3 broadened by various gases at temperatures between 160 and 300 K. Over 30 spectra were analyzed simultaneously using a multispectrum nonlinear least squares fitting technique to determine Lorentz air-broadening and pressure-induced shift coefficients along with their temperature dependences for selected transitions in the 3 fundamental band of (16)O3. We compare the present results with other measurements reported in the literature and with the ozone parameters on the 2000 and 2004 editions of the HITRAN database.

Temperature dependence of the hydrogen-broadening coefficient for the nu 9 fundamental of ethane

NASA Technical Reports Server (NTRS)

Halsey, G. W.; Hillman, J. J.; Nadler, Shacher; Jennings, D. E.

1988-01-01

Experimental results for the temperature dependence of the H2-broadening coefficient for the nu 9 fundamental of ethane are reported. Measurements were made over the temperature range 95-300 K using a novel low-temperature absorption cell. These spectra were recorded with the Doppler-limited diode laser spectrometer at NASA Goddard. The results are compared with recent measurements and model predictions.

Rotational broadening and conservation of angular momentum in post-extreme horizontal branch stars

NASA Astrophysics Data System (ADS)

Fontaine, G.; Latour, M.

2018-06-01

We show that the recent realization that isolated post-extreme horizontal branch (post-EHB) stars are generally characterized by rotational broadening with values of V rot sini between 25 and 30 km s-1 can be explained as a natural consequence of the conservation of angular momentum from the previous He-core burning phase on the EHB. The progenitors of these evolved objects, the EHB stars, are known to be slow rotators with an average value of V rot sini of 7.7 km s-1. This implies significant spin-up between the EHB and post-EHB phases. Using representative evolutionary models of hot subdwarf stars, we demonstrate that angular momentum conservation in uniformly rotating structures (rigid-body rotation) boosts that value of the projected equatorial rotation speed by a factor 3.6 by the time the model has reached the region of the surface gravity-effective temperature plane where the newly-studied post-EHB objects are found. This is exactly what is needed to account for their observed atmospheric broadening. We note that the decrease of the moment of inertia causing the spin-up is mostly due to the redistribution of matter that produces more centrally-condensed structures in the post-EHB phase of evolution, not to the decrease of the radius per se.

Reprint of: Virus-Specific T Cells: Broadening Applicability.

PubMed

Barrett, A John; Prockop, Susan; Bollard, Catherine M

2018-03-01

Virus infection remains an appreciable cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). Although pharmacotherapy and/or antibody therapy may help prevent or treat viral disease, these drugs are expensive, toxic, and often ineffective due to primary or secondary resistance. Further, effective treatments are limited for many infections (eg, adenovirus, BK virus), which are increasingly detected after alternative donor transplants. These deficiencies in conventional therapeutics have increased interest in an immunotherapeutic approach to viral disorders, leading to adoptive transfer of virus-specific cytotoxic T lymphocytes (VSTs), which can rapidly reconstitute antiviral immunity post-transplantation without causing graft-versus-host disease. This review will explore how the VST field has improved outcomes for many patients with life-threatening viral infections after HSCT, and how to broaden applicability beyond the "patient-specific" products, as well as extending to other viral diseases even outside the context of HSCT. Copyright © 2018. Published by Elsevier Inc.

Dynamic Stark broadening as the Dicke narrowing effect

NASA Astrophysics Data System (ADS)

Calisti, A.; Mossé, C.; Ferri, S.; Talin, B.; Rosmej, F.; Bureyeva, L. A.; Lisitsa, V. S.

2010-01-01

A very fast method to account for charged particle dynamics effects in calculations of spectral line shape emitted by plasmas is presented. This method is based on a formulation of the frequency fluctuation model (FFM), which provides an expression of the dynamic line shape as a functional of the static distribution of frequencies. Thus, the main numerical work rests on the calculation of the quasistatic Stark profile. This method for taking into account ion dynamics allows a very fast and accurate calculation of Stark broadening of atomic hydrogen high- n series emission lines. It is not limited to hydrogen spectra. Results on helium- β and Lyman- α lines emitted by argon in microballoon implosion experiment conditions compared with experimental data and simulation results are also presented. The present approach reduces the computer time by more than 2 orders of magnitude as compared with the original FFM with an improvement of the calculation precision, and it opens broad possibilities for its application in spectral line-shape codes.

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.

Complete wavelength mismatching effect in a Doppler broadened Y-type six-level EIT atomic medium

NASA Astrophysics Data System (ADS)

Bharti, Vineet; Wasan, Ajay

We present a theoretical study of the Doppler broadened Y-type six-level atomic system, using a density matrix approach, to investigate the effect of varying control field wavelengths and closely spaced hyperfine levels in the 5P state of 87Rb. The closely spaced hyperfine levels in our six-level system affect the optical properties of Y-type system and cause asymmetry in absorption profiles. Depending upon the choices of π-probe, σ+-control and σ--control fields transitions, we consider three regimes: (i) perfect wavelength matching regime (λp=λ=λ), (ii) partial wavelength mismatching regime (λp≠λ=λ), and (iii) complete wavelength mismatching regime (λp≠λ≠λ). The complete wavelength mismatching regime is further distinguished into two situations, i.e., λ<λ and λ>λ. We have shown that in the room temperature atomic vapor, the asymmetric transparency window gets broadened in the partial wavelength mismatching regime as compared to the perfect wavelength matching regime. This broad transparency window also splits at the line center in the complete wavelength mismatching regime.

The impact of column connection on band broadening in very high pressure liquid chromatography.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Guiochon, Georges

2013-09-01

A series of experiments was conducted to evaluate the degree of band broadening in very high pressure LC due to column connections. Different column manufacturers use slightly different designs for their column fittings. If the same column connections are repeatedly used to attach columns of different origins, different void volumes form between capillary tubes and column inlets. An Agilent Ultra Low Dispersion Kit (tubing id 75 μm) was installed on an Agilent Infinity 1290 ultra HPLC and used to connect successively an Agilent, a Phenomenex, and a Waters column. A series of uracil (unretained) samples were injected and eluted at a wide range of flow rates with a water/acetonitrile mixture as eluent. In order to determine the variance contribution from column connections as accurately as possible a nonretained probe compound was selected because the variance contribution from the column is the smallest for analytes, which have very low k values. Yet, this effect still has an impact on the resolution for moderately retained compounds (k > 2) for narrow-bore columns packed with fine particles, since variance contributions are additive for linear chromatographic systems. Each injection was replicated five times under the same experimental conditions. Then NanoViper column connections (tubing id 75 μm) were used and the same injections were made. This system was designed to minimize connection void volumes for any column. Band variances were calculated as the second central moment of elution peaks and used to assess the degree of band broadening due to the column connections. Band broadening may increase from 3.8 to 53.9% when conventional metal ferrules were used to join columns to connection sites. The results show that the variance contribution from improper connections can generate as much as 60.5% of the total variance observed. This demonstrates that column connections can play a larger role than the column packing with respect to band dispersion. © 2013 WILEY

Temporal contrast enhancement of a femtosecond fiber CPA system by filtering of SPM broadened spectra

NASA Astrophysics Data System (ADS)

Buldt, J.; Müller, M.; Klas, R.; Eidam, T.; Limpert, J.; Tünnermann, A.

2018-02-01

We present a novel approach for temporal contrast enhancement of energetic laser pulses by filtered SPM broadened spectra. A measured temporal contrast enhancement by at least 7 orders of magnitude in a simple setup has been achieved. This technique is applicable to a wide range of laser parameters and poses a highly efficient alternative to existing contrast-enhancement methods.

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinh, Thanh-Chung; Renger, Thomas, E-mail: thomas.renger@jku.at

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. Somore » far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening.

PubMed

Dinh, Thanh-Chung; Renger, Thomas

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. So far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures

Microwave beam broadening due to turbulent plasma density fluctuations within the limit of the Born approximation and beyond

NASA Astrophysics Data System (ADS)

Köhn, A.; Guidi, L.; Holzhauer, E.; Maj, O.; Poli, E.; Snicker, A.; Weber, H.

2018-07-01

Plasma turbulence, and edge density fluctuations in particular, can under certain conditions broaden the cross-section of injected microwave beams significantly. This can be a severe problem for applications relying on well-localized deposition of the microwave power, like the control of MHD instabilities. Here we investigate this broadening mechanism as a function of fluctuation level, background density and propagation length in a fusion-relevant scenario using two numerical codes, the full-wave code IPF-FDMC and the novel wave kinetic equation solver WKBeam. The latter treats the effects of fluctuations using a statistical approach, based on an iterative solution of the scattering problem (Born approximation). The full-wave simulations are used to benchmark this approach. The Born approximation is shown to be valid over a large parameter range, including ITER-relevant scenarios.

Stark broadening of the B III 2s-2p lines

NASA Astrophysics Data System (ADS)

Griem, Hans R.; Ralchenko, Yuri V.; Bray, Igor

1997-12-01

We present a quantum-mechanical calculation of Stark linewidths from electron-ion collisions for the 2s1/2-2p1/2,3/2, λ=2066 and 2067 Å, resonance transitions in B III. The results confirm previous quantum-mechanical R-matrix calculations, but contradict recent measurements and semiclassical and some semiempirical calculations. The differences between the calculations can be attributed to the dominance of small L partial waves in the electron-atom scattering, while the large Stark widths inferred from the measurements would be substantially reduced if allowance is made for hydrodynamic turbulence from high-Reynolds-number flows and the associated Doppler broadening.

Statistical Fine Structure in the Inhomogeneously Broadened Electronic Origin of Pentacene in p-Terphenyl.

DTIC Science & Technology

1988-01-29

Electronic Origin of Pentacene in p-Terphenyl by T. P. Carter, M. Manavi, and W. E. Moerner Prepared for Publication inDTIC Journal of Chemical Physics...Classification) Statistical Fine Structure in the Inhomogeneously Broadened Electronic Origin of Pentacene in p-Terphenyl 12. PERSONAL AUTHOR(S) T. P...of pentacene in p-terphenyl using laser FM spectroscopy. Statistical fine structure is time-independent structure on the inhomogeneous line caused by

Collision induced broadening of ν1 band and ground state spectral lines of sulfur dioxide perturbed by N2 and O2

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

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

Cross-phase modulation-induced spectral broadening in silicon waveguides.

PubMed

Zhang, Yanbing; Husko, Chad; Lefrancois, Simon; Rey, Isabella H; Krauss, Thomas F; Schröder, Jochen; Eggleton, Benjamin J

2016-01-11

We analytically and experimentally investigate cross-phase modulation (XPM) in silicon waveguides. In contrast to the well known result in pure Kerr media, the spectral broadening ratio of XPM to self-phase modulation is not two in the presence of either two-photon absorption (TPA) or free carriers. The physical origin of this change is different for each effect. In the case of TPA, this nonlinear absorption attenuates and slightly modifies the pulse shape due to differential absorption in the pulse peak and wings. When free carriers are present two different mechanisms modify the dynamics. First, free-carrier absorption performs a similar role to TPA, but is additionally asymmetric due to the delayed free-carrier response. Second, free-carrier dispersion induces an asymmetric blue phase shift which competes directly with the symmetric Kerr-induced XPM red shift. We confirm this analysis with pump-probe experiments in a silicon photonic crystal waveguide.

Leveraging biology interest to broaden participation in the geosciences

NASA Astrophysics Data System (ADS)

Perin, S.; Conner, L.; Oxtoby, L.

2017-12-01

It has been well documented that female participation in the geoscience workforce is low. By contrast, the biology workforce has largely reached gender parity. These trends are rooted in patterns of interest among youth. Specifically, girls tend to like biology and value social and societal connections to science (Brotman & Moore 2008). Our NSF-funded project, "BRIGHT Girls," offers two-week summer academies to high school-aged girls, in which the connections between the geosciences and biology are made explicit. We are conducting qualitative research to trace the girls' identity work during this intervention. Using team-based video interaction analysis, we are finding that the fabric of the academy allows girls to "try on" new possible selves in science. Our results imply that real-world, interdisciplinary programs that include opportunities for agency and authentic science practice may be a fruitful approach for broadening participation in the geosciences.

An Age-Related Mechanism of Emotion Regulation: Regulating Sadness Promotes Children's Learning by Broadening Information Processing

ERIC Educational Resources Information Center

Davis, Elizabeth L.

2016-01-01

Emotion regulation predicts positive academic outcomes like learning, but little is known about "why". Effective emotion regulation likely promotes learning by broadening the scope of what may be attended to after an emotional event. One hundred twenty-six 6- to 13-year-olds' (54% boys) regulation of sadness was examined for changes in…

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.

CO2-, He- and H2-broadening coefficients of SO2 for ν1 band and ground state transitions for astrophysical applications

NASA Astrophysics Data System (ADS)

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

2017-12-01

The discovery of the Universe and of the interstellar medium (ISM) is based on the knowledge of the molecules that are present in those places. Most of our understanding about the composition of the ISM and planetary atmospheres has been made possible almost entirely thanks to spectroscopic observations. Sulfur dioxide, SO2, is one of the about 200 molecules that have been detected in the ISM or circumstellar shells. In addition to its astrophysical relevance, SO2 has a proved role in the Earth's atmosphere. It origins from biomass burning and volcanic eruptions and directly enters in the sulfur cycle. In this work high-resolution tunable diode laser (TDL) infrared (IR) spectroscopy and mm-/sub-mm wave spectroscopy are exploited to retrieve the broadening parameters of sulfur dioxide perturbed by H2, He and CO2. IR measurements are carried out for ν1 band transitions around 9 μm by using He and CO2 as damping gases. As far as the vibrational ground state is concerned, about 20 rotational transitions are analyzed by means of the speed dependent Voigt profile to retrieve H2- and He-broadening coefficients. From the experimental results some conclusions about the quantum number dependence of the H2-, CO2- and He-collisional cross sections are drawn. Both IR and MW experiments highlight a very weak dependence of He broadening parameters on the Ka and J rotational quantum numbers. In a similar way, also SO2-H2 broadening coefficients show a negligible dependence on the rotational quantum numbers. Conversely, when CO2 is employed as perturbing species, the observed collisional cross sections tend to decrease with increasing Ka values and to increase against J, at least over the range of quantum numbers considered. The present results provide the first systematic determination of line-by-line SO2-CO2 broadening coefficients and they are of relevance to increase the potential use of spectroscopic databases for astronomical applications.

Broadening of Distribution of Trap States in PbS Quantum Dot Field-Effect Transistors with High-k Dielectrics

PubMed Central

2017-01-01

We perform a quantitative analysis of the trap density of states (trap DOS) in PbS quantum dot field-effect transistors (QD-FETs), which utilize several polymer gate insulators with a wide range of dielectric constants. With increasing gate dielectric constant, we observe increasing trap DOS close to the lowest unoccupied molecular orbital (LUMO) of the QDs. In addition, this increase is also consistently followed by broadening of the trap DOS. We rationalize that the increase and broadening of the spectral trap distribution originate from dipolar disorder as well as polaronic interactions, which are appearing at strong dielectric polarization. Interestingly, the increased polaron-induced traps do not show any negative effect on the charge carrier mobility in our QD devices at the highest applied gate voltage, giving the possibility to fabricate efficient low-voltage QD devices without suppressing carrier transport. PMID:28084725

Vacancy defects in electron-irradiated ZnO studied by Doppler broadening of annihilation radiation

NASA Astrophysics Data System (ADS)

Chen, Z. Q.; Betsuyaku, K.; Kawasuso, A.

2008-03-01

Vacancy defects in ZnO induced by electron irradiation were characterized by the Doppler broadening of annihilation radiation measurements together with the local density approximation calculations. Zinc vacancies (VZn) are responsible for positron trapping in the as-irradiated state. These are annealed out below 200°C . The further annealing at 400°C results in the formation of secondary defects attributed to the complexes composed of zinc vacancies and zinc antisites (VZn-ZnO) .

A Systematic Survey for Broadened CO Emission toward Galactic Supernova Remnants

NASA Astrophysics Data System (ADS)

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 12CO 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 12CO 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.

Doppler-broadening measurements of x-ray lines for determination of the ion temperature in tokamak plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bitter, M.; von Goeler, S.; Horton, R.

1979-01-29

Ion-temperature results are deduced from Doppler-broadening measurements of the K..cap alpha.. (1s-2p) resonance line emitted from heliumlike iron impurity ions in the hot central core of PLT (Princeton Large Torus) tokamak discharges. The measurements were performed using a high-resolution Bragg-crystal spectrometer with a multiwire proportional counter.

Influence of broadening and high-injection effects on GaAs-AlGaAs quantum well lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blood, P.; Colak, S.; Kucharska, A.I.

1988-08-01

The authors have calculated gain spectra and gain-current relations for GaAs-AlGaAs quantum well lasers using a model which incorporates a phenomenological description of bandgap narrowing due to many-body effects at high injection, transmission broadening by a carrier-density-dependent intraband scattering process, and broadening of the density of states function by fluctuations in the well width. The justification for including all these phenomena is made by examining spontaneous emission spectra observed through contact windows on quantum well layers. Using reasonable values of the parameters describing these effects, the model predicts correctly the observed lengthening of the laser emission wavelength with respect tomore » the absorption edge and correctly describes the variation of this wavelength, which they have observed for a set of devices with different numbers of quantum wells and the same well width. For a single GaAs quantum well laser 25 A wide, with the same parameters, the model predicts an increase in threshold current by a factor of 2.5 compared to an ideal quantum well without these effects.« less

Broadening of the R(0) and P(2) Lines in the 13CO Fundamental by Helium Atoms from 300 K down to 12 K: Measurements and Comparison with Close-Coupling Calculations

NASA Technical Reports Server (NTRS)

Thibault, F.; Mantz, A. W.; Claveau, C.; Valentin, A.; Hurtmans, D.

2007-01-01

We present measurements of He-broadening parameters for the R(0) and O(2) lines in the fundamental band of 13CO at different temperatures between 12K and room temperature. The broadening parameters are determined, taking into account confinement narrowing, by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The pressure broadening cross sections are deduced and compared to close-coupling calculations and earlier results obtained for rotational transitions of 12 CO.

Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - II: Experimental verification

NASA Astrophysics Data System (ADS)

Hausmaninger, Thomas; Silander, Isak; Ma, Weiguang; Axner, Ove

2016-01-01

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is normally described by an expression, here termed the conventional (CONV) description, that is restricted to the conventional cavity-limited weak absorption condition (CCLWA), i.e. when the single pass absorbance is significantly smaller than the empty cavity losses, i.e. when α0 L < < π / F. To describe NICE-OHMS signals beyond this limit two simplified extended descriptions (termed the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT), which are assumed to be valid under the relaxed cavity-limited weak absorption condition (RCLWA), i.e. when α0 L < π / F, and a full description (denoted FULL), presumed to be valid also when the α0 L < π / F condition does not hold, have recently been derived in an accompanying work (Ma W, et al. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical Description. J Quant Spectrosc Radiat Transfer, 2015, http://dx.doi.org/10.1016/j.jqsrt.2015.09.007). The present work constitutes an experimental verification and assessment of the validity of these, performed in the Doppler limit for a set of Fα0 L / π values (up to 3.5); it is shown under which conditions the various descriptions are valid. It is concluded that for samples with Fα0 L / π up to 0.01, all descriptions replicate the data well. It is shown that the CONV description is adequate and provides accurate assessments of the signal strength (and thereby the analyte concentration) up to Fα0 L / π of around 0.1, while the ELET is accurate for Fα0 L / π up to around 0.3. The ELFT description mimics the Db NICE-OHMS signal well for Fα0 L / π up to around unity, while the FULL description is adequate for all Fα0 L / π values investigated. Access to these descriptions both increases considerably the dynamic range of the technique and

Additional band broadening of peptides in the first size-exclusion chromatographic dimension of an automated stop-flow two-dimensional high performance liquid chromatography.

PubMed

Xu, Jucai; Sun-Waterhouse, Dongxiao; Qiu, Chaoying; Zhao, Mouming; Sun, Baoguo; Lin, Lianzhu; Su, Guowan

2017-10-27

The need to improve the peak capacity of liquid chromatography motivates the development of two-dimensional analysis systems. This paper presented a fully automated stop-flow two-dimensional liquid chromatography system with size exclusion chromatography followed by reversed phase liquid chromatography (SEC×RPLC) to efficiently separate peptides. The effects of different stop-flow operational parameters (stop-flow time, peak parking position, number of stop-flow periods and column temperature) on band broadening in the first dimension (1 st D) SEC column were quantitatively evaluated by using commercial small proteins and peptides. Results showed that the effects of peak parking position and the number of stop-flow periods on band broadening were relatively small. Unlike stop-flow analysis of large molecules with a long running time, additional band broadening was evidently observed for small molecule analytes due to the relatively high effective diffusion coefficient (D eff ). Therefore, shorter analysis time and lower 1 st D column temperature were suggested for analyzing small molecules. The stop-flow two-dimensional liquid chromatography (2D-LC) system was further tested on peanut peptides and an evidently improved resolution was observed for both stop-flow heart-cutting and comprehensive 2D-LC analysis (in spite of additional band broadening in SEC). The stop-flow SEC×RPLC, especially heart-cutting analysis with shorter analysis time and higher 1 st D resolution for selected fractions, offers a promising approach for efficient analysis of complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Doppler Broadening and its Contribution to Compton Energy-Absorption Cross Sections: An Analysis of the Compton Component in Terms of Mass-Energy Absorption Coefficient

NASA Astrophysics Data System (ADS)

Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G. E.

2002-09-01

Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1°-180°. Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1°-180°, for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance.

Stark broadening parameters and transition probabilities of persistent lines of Tl II

NASA Astrophysics Data System (ADS)

de Andrés-García, I.; Colón, C.; Fernández-Martínez, F.

2018-05-01

The presence of singly ionized thallium in the stellar atmosphere of the chemically peculiar star χ Lupi was reported by Leckrone et al. in 1999 by analysis of its stellar spectrum obtained with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. Atomic data about the spectral line of 1307.50 Å and about the hyperfine components of the spectral lines of 1321.71 Å and 1908.64 Å were taken from different sources and used to analyse the isotopic abundance of thallium II in the star χ Lupi. From their results the authors concluded that the photosphere of the star presents an anomalous isotopic composition of Tl II. A study of the atomic parameters of Tl II and of the broadening by the Stark effect of its spectral lines (and therefore of the possible overlaps of these lines) can help to clarify the conclusions about the spectral abundance of Tl II in different stars. In this paper we present calculated values of the atomic transition probabilities and Stark broadening parameters for 49 spectral lines of Tl II obtained by using the Cowan code including core polarization effects and the Griem semiempirical approach. Theoretical values of radiative lifetimes for 11 levels (eight with experimental values in the bibliography) are calculated and compared with the experimental values in order to test the quality of our results. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed. Trends of our calculated Stark width for the isoelectronic sequence Tl II-Pb III-Bi IV are also displayed.

Low-Temperature Collisional Broadening in the Far-Infrared Centrifugal Distortion Spectrum of CH_4

NASA Astrophysics Data System (ADS)

Boudon, Vincent; Vander Auwera, Jean; Manceron, Laurent; Kwabia Tchana, F.; Gabard, Tony; Amyay, Badr; Faye, Mbaye

2015-06-01

Previously, we could record on the AILES Beamline at the SOLEIL Synchrotron facility the first resolved centrifugal distorsion spectrum of methane (CH_4) in the THz region, which led to a precise determination of line intensities Later, we could measure collisional self- and N_2-broadening coefficients at room temperature. This time, we reinvestigated this topic by measuring these broadening coefficients at low temperature (between 120~K and 160~K) for J=5 to 12, thanks to a cryogenic multipass cell. We used a 93~m total optical path length. Five pure methane pressures (from 10 to 100 mbar) and four CH_4/N_2 mixtures (20~% of methane with a total pressure from 100 to 800 mbar) were used. These measurements allow us to obtain data for physical conditions approaching those of Titan's atmosphere and to estimate temperature exponents. V. Boudon, O. Pirali, P. Roy, J.-B. Brubach, L. Manceron and J. Vander Auwera, J. Quant. Spectrosc. Radiate. Transfer, 111, 1117--1129 (2010). M. Sanzharov, J. Vander Auwera, O. Pirali, P. Roy, J.-B. Brubach, L. Manceron, T. Gabard and V. Boudon, J. Quant. Spectrosc. Radiate. Transfer, 113, 1874--1886 (2012). F. Kwabia Tchana, F. Willaert, X. Landshere, J.-M. Flaud, L. Lago, M. Chapuis, C. Herbeaux, P. Roy and L. Manceron, Rev. Sci. Instrum., 84, 093101 (2013).

The effect of density fluctuations on electron cyclotron beam broadening and implications for ITER

NASA Astrophysics Data System (ADS)

Snicker, A.; Poli, E.; Maj, O.; Guidi, L.; Köhn, A.; Weber, H.; Conway, G.; Henderson, M.; Saibene, G.

2018-01-01

We present state-of-the-art computations of propagation and absorption of electron cyclotron waves, retaining the effects of scattering due to electron density fluctuations. In ITER, injected microwaves are foreseen to suppress neoclassical tearing modes (NTMs) by driving current at the q=2 and q=3/2 resonant surfaces. Scattering of the beam can spoil the good localization of the absorption and thus impair NTM control capabilities. A novel tool, the WKBeam code, has been employed here in order to investigate this issue. The code is a Monte Carlo solver for the wave kinetic equation and retains diffraction, full axisymmetric tokamak geometry, determination of the absorption profile and an integral form of the scattering operator which describes the effects of turbulent density fluctuations within the limits of the Born scattering approximation. The approach has been benchmarked against the paraxial WKB code TORBEAM and the full-wave code IPF-FDMC. In particular, the Born approximation is found to be valid for ITER parameters. In this paper, we show that the radiative transport of EC beams due to wave scattering in ITER is diffusive unlike in present experiments, thus causing up to a factor of 2-4 broadening in the absorption profile. However, the broadening depends strongly on the turbulence model assumed for the density fluctuations, which still has large uncertainties.

Experimental studies by complementary terahertz techniques and semi-classical calculations of N2- broadening coefficients of CH335Cl

NASA Astrophysics Data System (ADS)

Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R. A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.

2012-07-01

Room-temperature N2-broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH3Cl-N2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.

Does Positive Affect Broaden and Negative Affect Narrow Attentional Scope? A New Answer to an Old Question

ERIC Educational Resources Information Center

Huntsinger, Jeffrey R.

2012-01-01

The current research challenges the common view that positive affect and negative affect generate a broadened or narrowed attentional focus, respectively. Contrary to this view, two studies found that the link between affect and attentional focus as measured by a traditional flanker task (Study 1) and a modified flanker task (Study 2) reflects…

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.

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.

Egyptian government broadens ban on female genital mutilation.

PubMed

1996-01-01

An estimated 70-90% of girls in Egypt are subjected to female genital mutilation (FGM) before reaching puberty. Many Egyptians believe the practice to be ordained by Islam. Whether this is true, however, remains an issue of debate among Muslim scholars. Some Egyptian Christians also secure FGM for their girls. Egyptian law prohibits anyone without medical training from performing FGM, and any physician or health worker who causes permanent damage to a girl may face 3-10 years of hard labor. However, the law is frequently ignored, especially in rural areas, where village barbers and midwives perform the operations. In October 1995, Egyptian state hospitals were banned from performing FGM. Egypt has since broadened its ban to bar all health care workers in both state-run hospitals and private clinics from performing the procedure. No health care worker affiliated with the Ministry of Health is therefore allowed to perform FGM. Almost all Egyptian doctors are affiliated with the Ministry. While this recent move by the Health Minister is laudable, it remains to be seen whether he can enforce it. The secretary-general of the Egyptian Organization for Human Rights has urged parliament to enact legislation criminalizing FGM.

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

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.

Longitudinal mode selection in a delay-line homogeneously broadened oscillator with a fast saturable amplifier.

PubMed

Fleyer, Michael; Horowitz, Moshe

2017-05-01

Homogeneously broadened delay-line oscillators such as lasers or optoelectronic oscillators (OEOs) can potentially oscillate in a large number of cavity modes that are supported by their amplifier bandwidth. In a continuous wave operating mode, the oscillating mode is selected between one or few cavity modes that experience the highest small-signal gain. In this manuscript, we show that the oscillation mode of a homogeneously broadened oscillator can be selected from a large number of modes in a frequency region that can be broader than the full width at half maximum of the effective cavity filter. The mode is selected by a short-time injection of an external signal into the oscillator. After the external signal is turned off, the oscillation is maintained in the selected mode even if this mode has a significantly lower small-signal gain than that of other cavity modes. The stability of the oscillation is obtained due to nonlinear saturation effect in the oscillator amplifier. We demonstrate, experimentally and theoretically, mode selection in a long cavity OEO. We could select any desired mode between 400 cavity modes while maintaining ultra-low phase noise in the selected mode and in the non-oscillating modes. No mode-hopping was observed during our maximum measurement duration of about 24 hours.

OPACITY BROADENING OF {sup 13}CO LINEWIDTHS AND ITS EFFECT ON THE VARIANCE-SONIC MACH NUMBER RELATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Correia, C.; De Medeiros, J. R.; Burkhart, B.

2014-04-10

We study how the estimation of the sonic Mach number (M{sub s} ) from {sup 13}CO linewidths relates to the actual three-dimensional sonic Mach number. For this purpose we analyze MHD simulations that include post-processing to take radiative transfer effects into account. As expected, we find very good agreement between the linewidth estimated sonic Mach number and the actual sonic Mach number of the simulations for optically thin tracers. However, we find that opacity broadening causes M{sub s} to be overestimated by a factor of ≈1.16-1.3 when calculated from optically thick {sup 13}CO lines. We also find that there ismore » a dependence on the magnetic field: super-Alfvénic turbulence shows increased line broadening compared with sub-Alfvénic turbulence for all values of optical depth for supersonic turbulence. Our results have implications for the observationally derived sonic Mach number-density standard deviation (σ{sub ρ/(ρ)}) relationship, σ{sub ρ/〈ρ〉}{sup 2}=b{sup 2}M{sub s}{sup 2}, and the related column density standard deviation (σ {sub N/(N)}) sonic Mach number relationship. In particular, we find that the parameter b, as an indicator of solenoidal versus compressive driving, will be underestimated as a result of opacity broadening. We compare the σ {sub N/(N)}-M{sub s} relation derived from synthetic dust extinction maps and {sup 13}CO linewidths with recent observational studies and find that solenoidally driven MHD turbulence simulations have values of σ {sub N/(N)}which are lower than real molecular clouds. This may be due to the influence of self-gravity which should be included in simulations of molecular cloud dynamics.« less

Spectral Line Parameters Including Temperature Dependences of Self- and Air-Broadening in the 2 (left arrow) 0 Band of CO at 2.3 micrometers

NASA Technical Reports Server (NTRS)

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

2012-01-01

Temperature dependences of pressure-broadened half-width and pressure-induced shift coefficients along with accurate positions and intensities have been determined for transitions in the 2<--0 band of C-12 O-16 from analyzing high-resolution and high signal-to-noise spectra recorded with two different Fourier transform spectrometers. A total of 28 spectra, 16 self-broadened and 12 air-broadened, recorded using high- purity (greater than or equal to 99.5% C-12-enriched) CO samples and CO diluted with dry air(research grade) at different temperatures and pressures, were analyzed simultaneously to maximize the accuracy of the retrieved parameters. The sample temperatures ranged from 150 to 298K and the total pressures varied between 5 and 700 Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to adjust the rovibrational constants (G, B, D, etc.) and intensity parameters (including Herman-Wallis coefficients), rather than determining individual line positions and intensities. Self-and air-broadened Lorentz half-width coefficients, their temperature dependence exponents, self- and air-pressure-induced shift coefficients, their temperature dependences, self- and air-line mixing coefficients, their temperature dependences and speed dependence have been retrieved from the analysis. Speed-dependent line shapes with line mixing employing off-diagonal relaxation matrix element formalism were needed to minimize the fit residuals. This study presents a precise and complete set of spectral line parameters that consistently reproduce the spectrum of carbon monoxide over terrestrial atmospheric conditions.

Rotational level-dependent collisional broadening and line shift of the A2Sigma(+)-X2Pi (1,0) band of OH in hydrogen-air combustion gases

NASA Technical Reports Server (NTRS)

Kessler, W. J.; Allen, M. G.; Davis, S. J.

1993-01-01

Measurements of the collisional broadening and line shift of the (1,0) band of the A2Sigma(+)-X2Pi system of OH are reported in atmospheric pressure hydrogen-air combustion gases. The measurements were made using a single-mode, narrow linewidth, frequency-doubled ring dye laser operating near 283 nm. The OH was generated in the combustion gases of a flat flame H2-air burner. Collisional broadening parameters for equilibrium mixtures of H2, O2, H2O, and N2 were obtained spanning a range of fuel/air equivalence ratios from 0.6 to 1.6 and temperatures from 1500 to 2050 K. Measurements were obtained spanning rotational quantum numbers from 4.5 to 16.5. The collision induced frequency shift was determined to be 0.1 that of the collisional broadening.

Determination of Lateral Diffusivity in Single Pixel X-ray Absorbers with Implications for Position Dependent Excess Broadening

NASA Technical Reports Server (NTRS)

Saab, T.; Figueroa-Feliciano, E.; Iyomoto, N.; Bandler, S. R.; Chervenak, J.; Finkbeiner, F.; Kelley, R.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J.

2005-01-01

An ideal microcalorimeter is characterized by a constant energy resolution across the sensor's dynamic range. Any dependence of pulse shape on the position within the absorber where an event occurs leads to a degradation in resolution that is linear with event s energy (excess broadening). In this paper we present a numerical simulation that was developed to model the variation in pulse shape with position based on the thermal conductivity within the absorber and between the absorber, sensor, and heat bath, for arbitrarily shaped absorbers and sensors. All the parameters required for the simulation can be measured from actual devices. We describe how the thermal conductivity of the absorber material is determined by comparing the results of this model with data taken from a position sensitive detector in which any position dependent effect is purposely emphasized by making a long, narrow absorber that is read out by sensors on both end. Finally, we present the implications for excess broadening given the measured parameters of our X-ray microcalorimeters.

Effects of phonon broadening on x-ray near-edge spectra in molecular crystals

NASA Astrophysics Data System (ADS)

Vinson, John; Jach, Terrence; Elam, Tim; Denlinger, Jonathon

2014-03-01

Calculations of near-edge x-ray spectra are often carried out using the average atomic coordinates from x-ray or neutron scattering experiments or from density functional theory (DFT) energy minimization. This neglects disorder from thermal and zero-point vibrations. Here we look at the nitrogen K-edge of ammonium chloride and ammonium nitrate, comparing Bethe-Salpeter calculations of absorption and fluorescence to experiment. We find that intra-molecular vibrational effects lead to significant, non-uniform broadening of the spectra, and that for some features zero-point motion is the primary source of the observed shape.

Convergence of Legendre Expansion of Doppler-Broadened Double Differential Elastic Scattering Cross Section

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arbanas, Goran; Dunn, Michael E; Larson, Nancy M

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.

Dielectric spectra broadening as a signature for dipole-matrix interaction. III. Water in adenosine monophosphate/adenosine-5'-triphosphate solutions.

PubMed

Puzenko, Alexander; Levy, Evgeniya; Shendrik, Andrey; Talary, Mark S; Caduff, Andreas; Feldman, Yuri

2012-11-21

In this, the third part of our series on the dielectric spectrum symmetrical broadening of water, we consider the nucleotide aqueous solutions. Where in Parts I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)] and II [E. Levy et al., J. Chem. Phys. 136, 114503 (2012)], the dipole-dipole or ion-dipole interaction had a dominant feature, now the interplay between these two types of dipole-matrix interactions will be considered. We present the results of high frequency dielectric measurements of different concentrations of adenosine monophosphate/adenosine-5'-triphosphate aqueous solutions. We observed the Cole-Cole broadening of the main relaxation peak of the solvent in the solutions. Moreover, depending on the nucleotide concentration, we observed both types of dipole-matrix interaction. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the two types of interaction.

The Best and the Brightest in Geosciences: Broadening Representation in the Field

NASA Astrophysics Data System (ADS)

Myles, L.

2017-12-01

Geoscience research in government agencies and universities across the US is anchored by data collection from field and lab experiments. In these settings, the composition and the culture of the environment can be less welcoming for individuals from groups that are traditionally underrepresented in the geosciences. Ongoing efforts to address diversity and inclusion in the field and lab include top-down approaches that provide support and training for established geoscience leaders and bottom-up approaches that offer research internships and fellowships for students. To achieve success, effective strategies for broadening representation in the field must be developed and shared across the geosciences community to advance scientific innovation and create opportunities for success.

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.

Invited commentary: cross-cultural influences on sleep--broadening the environmental landscape.

PubMed

Bliwise, Donald L

2008-12-15

Recognition among epidemiologists of the adverse health consequences of sleep habits and sleep disorders has flourished in recent years. Identifying and understanding the cross-sectionally defined environmental factors that are associated with individual differences in habitual sleep duration represents an important line of inquiry. Because of the complexity of sleep as a behavior, traditional measures such as socioeconomic and marital status, health habits, and education may require supplementation with types of data that are both novel and less conventional. Studies across cultures offer one such possibility, although it may be necessary to broaden the view of the environment at both the macro level (e.g., seasonal, geographic, and climatic variation) and the micro level (the bedroom milieu and factors that affect it) in order to fully understand the scope of such influences.

THE CHARACTERIZATION OF A SOLID SORBENT WITH CRYSTALLITE SIZE AND STRAIN DATA FROM X-RAY DIFFRACTION LINE BROADENING

EPA Science Inventory

The paper gives results of the characterization of a solid sorbent with crystallite size and strain data from x-ray diffraction line broadening, as part of an EPA investigation of the injection of dry Ca(OH)2 into coal-fired electric power plant burners for the control of SO2 emi...

Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

NASA Technical Reports Server (NTRS)

Kirby, Kate; Babb, J.; Yoshino, K.

2004-01-01

In L-dwarfs and T-dwarfs the resonance lines of sodium and potassium are so profoundly pressure-broadened that their wings extend several hundred nanometers from line center. With accurate knowledge of the line profiles as a function of temperature and pressure: such lines can prove to be valuable diagnostics of the atmospheres of such objects. We have initiated a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Although potassium and sodium are the alkali species of most interest in the atmospheres of cool brown dwarfs and extrasolar giant planets, some of our theoretical focus this year has involved the calculation of pressure-broadening of lithium resonance lines by He, as a test of a newly developed suite of computer codes. In addition, theoretical calculations have been carried out to determine the leading long range van der Waals coefficients for the interactions of ground and excited alkali metal atoms with helium atoms, to within a probable error of 2%. Such data is important in determining the behavior of the resonance line profiles in the far wings. Important progress has been made on the experimental aspects of the program since the arrival of a postdoctoral fellow in September. A new absorption cell has been designed, which incorporates a number of technical improvements over the previous cell, including a larger cell diameter to enhance the signal, and fittings which allow for easier cleaning, thereby significantly reducing the instrument down-time.

Measurement of pressure-broadening and lineshift coefficients at 77 and 296 K of methane lines in the 727 nm band using intracavity laser spectroscopy

NASA Technical Reports Server (NTRS)

Singh, Kuldip; O'Brien, James J.

1994-01-01

Pressure-broadening coefficients and pressure-induced lineshifts of several rotational-vibrational lines have been measured in the 727 nm absorption band of methane at temperatures of 77 and 296 K, using nitrogen, hydrogen, and helium as the foreign-gas collision partners. A technique involving intracavity laser spectroscopy is used to record the methane spectra. Average values of the broadening coefficients (/cm/atm) at 77 K are: 0.199, 0.139, 0.055, and 0.29 for collision partners N2, H2, He, and CH4, respectively. Typical average values of the pressure-induced lineshifts (/cm/atm) at 77 K and for the range of foreign gas pressures between 10 and 200 torr are -0.052 for N2, -0.063 for H2, and +0.031 for He. All the values obtained at 296 K are considerably different from the corresponding values at 77 K. This represents the first report of pressure-broadening and shifting coefficients for the methane transitions in a region where the delta nu(sub C-H) = 5 band occurs.

Nonlinear dependence of X-ray diffraction peak broadening in In x Ga1‑ x Sb epitaxial layers on GaAs substrates

NASA Astrophysics Data System (ADS)

Hoang Huynh, Sa; Ha, Minh Thien Huu; Binh Do, Huy; Nguyen, Tuan Anh; Luc, Quang Ho; Chang, Edward Yi

2018-04-01

The configuration of the interfacial misfit array at In x Ga1‑ x Sb/GaAs interfaces with different indium compositions and thicknesses grown by metalorganic chemical vapor deposition was systematically analyzed using X-ray diffraction (XRD) reciprocal space maps (RSMs). These analyses confirmed that the epilayer relaxation was mainly contributed to by the high degree of spatial correlation of the 90° misfit array (correlation factors <0.01). The anisotropic peak-broadening aspect ratio was found to have a non-linear composition dependence as well as be thickness-dependent, related to the strain relaxation of the epilayer. However, the peak-broadening behavior in each RSM scan direction had different composition and thickness dependences.

Observation of Ortho-Para Dependence of Pressure Broadening Coefficient in Acetylene νb{1}+νb{3} Vibration Band Using Dual-Comb Spectroscopy

NASA Astrophysics Data System (ADS)

Iwakuni, Kana; Okubo, Sho; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki; Yamada, Koichi MT

2016-06-01

We observe that the pressure-broadening coefficients depend on the ortho-para levels. The spectrum is taken with a dual-comb spectrometer which has the resolution of 48 MHz and the frequency accuracy of 8 digit when the signal-to-noise ratio is more than 20. In this study, about 4.4-Tz wide spectra of the P(31) to R(31) transitions in the νb{1}+νb{3} vibration band of 12C_2H_2 are observed at the pressure of 25, 60, 396, 1047, 1962 and 2654 Pa. Each rotation-vibration absorption line is fitted to Voight function and we determined pressure-broadening coefficients for each rotation-vibration transition. The Figure shows pressure broadening coefficient as a function of m. Here m is J"+1 for R and -J" for P-branch. The graph shows obvious dependence on ortho and para. We fit it to Pade function considering the population ratio of three-to-one for the ortho and para levels. This would lead to detailed understanding of the pressure boarding mechanism. S. Okubo et al., Applied Physics Express 8, 082402 (2015)

Air- and Self-Broadened Half Widths, Pressure-Induced Shifts, and Line Mixing in the Nu(sub 2) Band of (12)CH4

NASA Technical Reports Server (NTRS)

Smith, M. A. H.; Benner, D. Chris; Pedroi-Cross, A.; Devi, V. Malathy

2013-01-01

Lorentz self- and air-broadened half width and pressure-induced shift coefficients and their dependences on temperature have been measured from laboratory absorption spectra for nearly 130 transitions in the nu(sub 2) band of (12)CH4. In addition line mixing coefficients (using the relaxation matrix element formalism) for both self- and airbroadening were experimentally determined for the first time for a small number of transitions in this band. Accurate line positions and absolute line intensities were also determined. These parameters were obtained by analyzing high-resolution (approx. 0.003 to 0.01 per cm) laboratory spectra of high-purity natural CH4 and air-broadened CH4 recorded at temperatures between 226 and 297 K using the McMath-Pierce Fourier transform spectrometer (FTS) located at the National Solar Observatory on Kitt Peak, Arizona. A multispectrum nonlinear least squares technique was used to fit short (5-15 per cm) spectral intervals in 24-29 spectra simultaneously. Parameters were determined for nu(sub 2) transitions up to J" = 16. The variations of the measured broadening and shift parameters with the rotational quantum number index and tetrahedral symmetry species are examined. The present results are also compared with previous measurements available in the literature.

Measured pressure broadening and shift rates of the 1. 73. mu. m (5 d (3/2) sub 1 --6 p (5/2) sub 2 ) transition of xenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hebner, G.A.; Hays, G.N.

1991-07-29

Pressure broadening and line center shift rates as a function of helium, neon, and argon pressure have been measured for the 1.73 {mu}m (5{ital d}(3/2){sub 1}--6{ital p}(5/2){sub 2}) transition in xenon. The pressure broadening rates are 20.3{plus minus}6.4, 12.7{plus minus} 3.5, and 19.7{plus minus}2.9 MHz/Torr for helium, neon, and argon buffers, respectively.

Some Notes on Neutron Up-Scattering and the Doppler-Broadening of High-Z Scattering Resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, Donald Kent

When neutrons are scattered by target nuclei at elevated temperatures, it is entirely possible that the neutron will actually gain energy (i.e., up-scatter) from the interaction. This phenomenon is in addition to the more usual case of the neutron losing energy (i.e., down-scatter). Furthermore, the motion of the target nuclei can also cause extended neutron down-scattering, i.e., the neutrons can and do scatter to energies lower than predicted by the simple asymptotic models. In recent years, more attention has been given to temperature-dependent scattering cross sections for materials in neutron multiplying systems. This has led to the inclusion of neutronmore » up-scatter in deterministic codes like Partisn and to free gas scattering models for material temperature effects in Monte Carlo codes like MCNP and cross section processing codes like NJOY. The free gas scattering models have the effect of Doppler Broadening the scattering cross section output spectra in energy and angle. The current state of Doppler-Broadening numerical techniques used at Los Alamos for scattering resonances will be reviewed, and suggestions will be made for further developments. The focus will be on the free gas scattering models currently in use and the development of new models to include high-Z resonance scattering effects. These models change the neutron up-scattering behavior.« less

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).

Self- and Air-Broadened Line Shape Parameters of (12)CH(4) : 4500-4620 cm(-1)

NASA Astrophysics Data System (ADS)

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

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 dependencies 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 FTS1. The 13 spectra used in the analysis consisted of seven pure 12CH4 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 technique2. The results will be compared to existing values reported in the literature3. as part of the GNU EPrints system , and is freely redistributable under the GPL .

Broadening the photoresponsive activity of anatase titanium dioxide particles via decoration with partial gold shells.

PubMed

Khantamat, Orawan; Li, Chien-Hung; Liu, Si-Ping; Liu, Tingting; Lee, Han Ju; Zenasni, Oussama; Lee, Tai-Chou; Cai, Chengzhi; Lee, T Randall

2018-03-01

Titanium dioxide (TiO 2 ) has gained increasing interest in materials research due to its outstanding properties and promising applications in a wide range of fields. From this perspective, we report the synthesis of custom-designed anatase TiO 2 submicrometer particles coated with partial Au shells (ATiO 2 -AuShl). The synthetic strategy used herein yields uniformly shaped monodisperse particles. Amorphous TiO 2 core particles were synthesized using template-free oxidation and hydrolysis of titanium nitride (TiN); subsequent hydrothermal treatment generated anatase TiO 2 (ATiO 2 ) particles. Coating ATiO 2 particles with partial Au shells was accomplished using a simple seeded-growth method. Evaluation of the optical properties of these ATiO 2 -AuShl particles showed that these submicrometer composites exhibited an intense absorption peak for TiO 2 in the UV region (∼326 nm) and a broad extinction band in the visible range (∼650 nm) arising from the incomplete Au shell. These ATiO 2 -AuShl composite particles provide a unique and effective means for broadening the optical response of TiO 2 -based nano- and micron-scale materials. The simplicity of our synthetic method should broaden the application of ATiO 2 -AuShl particles in various visible light-driven technologies. Copyright © 2017 Elsevier Inc. All rights reserved.

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

A comparative study of APLI and APCI in IMS at atmospheric pressure to reveal and explain peak broadening effects by the use of APLI.

PubMed

Ihlenborg, Marvin; Raupers, Björn; Gunzer, Frank; Grotemeyer, Jürgen

2015-11-21

The details of the ionization mechanism in atmospheric pressure are still not completely known. In order to obtain further insight into the occurring processes in atmospheric pressure laser ionization (APLI) a comparative study of atmospheric pressure chemical ionization (APCI) and APLI is presented in this paper. This study is carried out using similar experimental condition at atmospheric pressure employing a commercial ion mobility spectrometer (IMS). Two different peak broadening mechanisms can then be assigned, one related to a range of different species generated and detected, and furthermore for the first time a power broadening effect on the signals can be identified.

Formal Leadership of Department Chairpersons with a Broadening Span of Control in Restructured Community Colleges: A Multi-Case Study

ERIC Educational Resources Information Center

Fattig, Teri L.

2013-01-01

Community college department chairpersons have experienced a broadening span of control due to the restructuring tactics of community colleges and the approaches utilized in order to cope with decreased budgets and increased enrollments. Many community colleges used strategies which involved flattening the middle management section of the…

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.

Coherent perfect absorption in a homogeneously broadened two-level medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longhi, Stefano

2011-05-15

In recent works, it has been shown, rather generally, that the time-reversed process of lasing at threshold realizes a coherent perfect absorber (CPA). In a CPA, a lossy medium in an optical cavity with a specific degree of dissipation, equal in modulus to the gain of the lasing medium, can perfectly absorb coherent optical waves that are the time-reversed counterpart of the lasing field. Here, the time-reversed process of lasing is considered in detail for a homogeneously broadened two-level medium in an optical cavity and the conditions for CPA are derived. It is shown that, owing to the dispersive propertiesmore » of the two-level medium, exact time-reversal symmetry is broken and the frequency of the field at which CPA occurs is generally different than the one of the lasing mode. Moreover, at a large cooperation parameter, the observation of CPA in the presence of bistability requires one to operate in the upper branch of the hysteresis cycle.« less

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

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

NASA Technical Reports Server (NTRS)

Pine, A. S.

1989-01-01

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

CO2-broadening and shift coefficients in the ν3 and ν2 + (ν4 +ν5)+0 bands of acetylene

NASA Astrophysics Data System (ADS)

Lyulin, O. M.; Petrova, T. M.; Solodov, A. M.; Solodov, A. A.; Perevalov, V. I.

2018-03-01

The absorption spectra of the mixture of C2H2 and CO2 at different partial pressures of both gases have been recorded at room temperature in the 3 μm region using the Bruker IFS 125 HR FTIR spectrometer. The multispectrum fitting procedure has been applied to these spectra to recover the broadening and shift parameters of the acetylene spectral lines. The CO2 broadening and pressure induced shift coefficients for 119 lines of the ν3 and ν2 + (ν4 +ν5)+0 bands of acetylene have been derived. The rotational dependence of the values of these coefficients is discussed. The comparison of the obtained coefficients to those published by other authors for the ν1 + ν3 and (ν4 +ν5)+0 bands is performed.

Temperature dependence of the helium induced broadening and shift of the Rb D1 and D2 lines

NASA Astrophysics Data System (ADS)

Miller, Wooddy S.; Rice, Christopher A.; Perram, Glen P.

2018-02-01

The rates for collisional broadening and shifting of the Rb D1 (52S1/2 - 52P1/2) and D2 (52S1/2 - 52P3/2) transition induced by 4He have been measured at elevated temperatures of 373-723 K. The shift coefficients exhibit an increase of 20% from 4.36 MHz/Torr to 5.35 MHz/Torr for the D1 line and an 80% increase from 0.42 MHz/Torr to 0.99 MHz/Torr for the D2 line over the observed temperature range. Broadening coefficients exhibit a 6% increase from 17.8 MHz/Torr to 18.9 MHz/Torr and 10% from 18.5 MHz/Torr to 20.5 MHz/Torr for the D1 and D2 lines, respectively. The experimental values agree well with prior reported values within the temperature overlap regions of T < 394 K. Comparison to prior predictions from the Anderson-Talman theory using spin orbit multi reference (SOCI) ab initio potentials are superior to quantum treatments involving Allard and Baranger coupling.

Theory of controlling band-width broadening in terahertz sideband generation in semiconductors by a direct current electric field

NASA Astrophysics Data System (ADS)

Liu, Houquan; Zhang, Xingchu

2017-03-01

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

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.

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"…

Absolute intensities and self-, N2-, and air-broadened Lorentz halfwidths for selected lines in the nu3 band of (C-12)H3D from measurements with a tunable diode laser spectrometer

NASA Technical Reports Server (NTRS)

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

1986-01-01

Absolute intensities and self-, air- and N2-broadened half-widths have been determined for the first time for individual lines in the nu3(A1) band of (C-12)H3D near 7.6 microns from measurements of individual vibration-rotation lines using a tunable diode laser spectrometer. The intensity measurements are believed to be accurate to within three percent. Within experimental uncertainties, equal broadening efficiencies are found for both air and nitrogen. Self-broadened half-widths determined for three transitions yield an average half-width value of 0.803 + or -0.0010/cm/atm at 296 K.

Temperature dependence of Lorentz air-broadening and pressure-shift coefficients of (12)CH4 lines in the 2.3-micron spectral region

NASA Technical Reports Server (NTRS)

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

1994-01-01

High-resolution (0.01/cm) absorption spectra of lean mixtures of CH4 in dry air were recorded with the McMath-Pierce Fourier transform spectrometer (FTS) of the National Solar Observatory on Kitt Peak at various temperatures between 24 and -61 C. The spectra have been analyzed to determine the values at room temperature of pressure-broadened widths and pressure-induced shifts of more than 740 transitions. The temperature dependence of air-broadened widths and pressure-induced shifts was deduced for approx. 370 transitions in the nu(sub 1) + nu(sub 4), nu(sub 3) + nu(sub 4), and nu(sub 2) + nu(sub 3) bands of (12)CH4 located between 4118 and 4615/cm. These results were obtained by analyzing a total of 29 spectra simultaneously using a multi-spectral non-linear least-squares fitting technique. This new technique allowed the determination of correlated spectral line parameters (e.g. intensity and broadening coefficient) better than the procedure of averaging values obtained by fitting the spectra individually. This method also provided a direct determination of the uncertainties in the retrieved parameters due to random errors. For each band analysed in this study the dependence of the various spectral line parameters upon the tetrahedral symmetry species and the rotational quantum numbers of the transitions is also presented.

Relatively slow stochastic gene-state switching in the presence of positive feedback significantly broadens the region of bimodality through stabilizing the uninduced phenotypic state.

PubMed

Ge, Hao; Wu, Pingping; Qian, Hong; Xie, Xiaoliang Sunney

2018-03-01

Within an isogenic population, even in the same extracellular environment, individual cells can exhibit various phenotypic states. The exact role of stochastic gene-state switching regulating the transition among these phenotypic states in a single cell is not fully understood, especially in the presence of positive feedback. Recent high-precision single-cell measurements showed that, at least in bacteria, switching in gene states is slow relative to the typical rates of active transcription and translation. Hence using the lac operon as an archetype, in such a region of operon-state switching, we present a fluctuating-rate model for this classical gene regulation module, incorporating the more realistic operon-state switching mechanism that was recently elucidated. We found that the positive feedback mechanism induces bistability (referred to as deterministic bistability), and that the parameter range for its occurrence is significantly broadened by stochastic operon-state switching. We further show that in the absence of positive feedback, operon-state switching must be extremely slow to trigger bistability by itself. However, in the presence of positive feedback, which stabilizes the induced state, the relatively slow operon-state switching kinetics within the physiological region are sufficient to stabilize the uninduced state, together generating a broadened parameter region of bistability (referred to as stochastic bistability). We illustrate the opposite phenotype-transition rate dependence upon the operon-state switching rates in the two types of bistability, with the aid of a recently proposed rate formula for fluctuating-rate models. The rate formula also predicts a maximal transition rate in the intermediate region of operon-state switching, which is validated by numerical simulations in our model. Overall, our findings suggest a biological function of transcriptional "variations" among genetically identical cells, for the emergence of bistability and

Strategies for broadening participation in the Maryland Sea Grant REU program

NASA Astrophysics Data System (ADS)

Moser, F. C.; Kramer, J.; Allen, J. R.

2011-12-01

A core goal of the ocean science community is to increase gender and ethnic diversity in its scientific workforce. Maryland Sea Grant strives to provide women and students from underrepresented groups in marine science opportunities to participate in its NSF-supported Research Experiences for Undergraduates (REU) program in estuarine processes. While women currently dominate the applicant student pool, and often the accepted student pool, we are trying a variety of strategies to increase the number of applicants and accepted students from underrepresented groups who might not otherwise be lured into marine science research and, ultimately, careers. For example, we have built partnerships with multicultural-focused undergraduate research programs and institutions, which can raise awareness about our REU program and its commitment to broadening diversity. Further, we work to attract first generation college students, students from small colleges with limited marine science opportunities and students from varied racial and ethnic backgrounds using such strategies as: 1) developing trust and partnerships with faculty at minority serving institutions; 2) expanding our outreach in advertising our program; 3) recruiting potential applicants at professional meetings; 4) targeting minority serving institutions within and beyond our region; 5) encouraging our REU alumni to promote our REU program among their peers; and 6) improving our application process. We believe these efforts contribute to the increase in the diversity of our summer-supported students and the change in the composition of our applicant pool over the last decade. Although we cannot definitively identify which strategies are the most effective at broadening participation in our program, we attribute most of our improvements to some combination of these strategies. In addition, pre- and post-surveying of our REU students improves our understanding of effective tools for recruiting and adapting our program

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.

Comparison of numerical techniques for the evaluation of the Doppler broadening functions psi(x,theta) and chi(x,theta)

NASA Technical Reports Server (NTRS)

Canright, R. B., Jr.; Semler, T. T.

1972-01-01

Several approximations to the Doppler broadening functions psi(x, theta) and chi(x, theta) are compared with respect to accuracy and speed of evaluation. A technique, due to A. M. Turning (1943), is shown to be at least as accurate as direct numerical quadrature and somewhat faster than Gaussian quadrature. FORTRAN 4 listings are included.

0.4-1.4 μm Visible to Near-Infrared Widely Broadened Super Continuum Generation with Er-doped Ultrashort Pulse Fiber Laser System

NASA Astrophysics Data System (ADS)

Nishizawa, Norihiko; Mitsuzawa, Hideyuki; Sumimura, Kazuhiko

2009-03-01

Visible to near-infrared widely broadened super continuum generation is demonstrated using ultrashort-pulse fiber laser system. Er-doped fiber chirped-pulse amplification system operated at 1550 nm in wavelength is used for the amplifier system, which generated ultrashort-pulse of 112 fs in FWHM with output power of 160 mW, on average. Almost pedestal free 200 fs second harmonic generation pulse is generated at 780 nm region using periodically poled LiNbO3 and conversion efficiency is as high as 37%. 0.45-1.40 μm widely broadened super continuum is generated in highly nonlinear photonic crystal fiber and spectrum flatness is within ±6 dB. All of the fiber devices are fusion spliced so that this system shows a good stability.

Homogeneous Emission Line Broadening in the Organo Lead Halide Perovskite CH3NH3PbI3-xClx.

PubMed

Wehrenfennig, Christian; Liu, Mingzhen; Snaith, Henry J; Johnston, Michael B; Herz, Laura M

2014-04-17

The organic-inorganic hybrid perovskites methylammonium lead iodide (CH3NH3PbI3) and the partially chlorine-substituted mixed halide CH3NH3PbI3-xClx emit strong and broad photoluminescence (PL) around their band gap energy of ∼1.6 eV. However, the nature of the radiative decay channels behind the observed emission and, in particular, the spectral broadening mechanisms are still unclear. Here we investigate these processes for high-quality vapor-deposited films of CH3NH3PbI3-xClx using time- and excitation-energy dependent photoluminescence spectroscopy. We show that the PL spectrum is homogenously broadened with a line width of 103 meV most likely as a consequence of phonon coupling effects. Further analysis reveals that defects or trap states play a minor role in radiative decay channels. In terms of possible lasing applications, the emission spectrum of the perovskite is sufficiently broad to have potential for amplification of light pulses below 100 fs pulse duration.

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.

Mortality Salience and Positive Affect Influence Adolescents' Attitudes toward Peers with Physical Disabilities: Terror Management and Broaden and Build Theories

ERIC Educational Resources Information Center

Taubman-Ben-Ari, Orit; Eherenfreund-Hager, Ahinoam; Findler, Liora

2011-01-01

Attitudes toward teenagers with and without physical disabilities, and their social acceptance, were examined from the perspective of terror management theory and the broaden and build theory. Participants (n = 390, aged 13-17) were divided into 3 experimental conditions: positive emotions, mortality salience, and control. Then, they were shown…

- 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.

BASE (Broadening Access to Science Education): A Research and Mentoring Focused Summer STEM Camp Serving Underrepresented High School Girls

ERIC Educational Resources Information Center

Phelan, Shelley A.; Harding, Shannon M.; Harper-Leatherman, Amanda S.

2017-01-01

BASE (Broadening Access to Science Education) Camp is a hands-on, two-week residential summer science experience on the Fairfield University campus in Fairfield CT, USA. The annual program targets 24 young women who attend high school in the neighboring city of Bridgeport, CT, the most economically depressed city in CT. The camp, which is free to…

The Influence of Affirming Kindness and Community on Broadening Participation in STEM Career Pathways

PubMed Central

Estrada, Mica; Eroy-Reveles, Alegra; Matsui, John

2018-01-01

The United States’ inability to achieve equitable workforce development in science, technology, engineering, and mathematics (STEM) career pathways is well-recognized and has been attributed to the poor retention of a diverse stream of students in academia. Social science theory and research provide evidence that social contextual variables—specifically kindness cues affirming social inclusion—influence chronic underrepresentation of some groups within STEM career pathways. Review of the literature suggests that the current STEM academic context does not consistently provide cues that affirm social inclusion to all members of the academic population, and that policies that address this disparity are essential to broadening STEM workforce development in the United States. PMID:29657577

CH3D photomixing spectroscopy up to 2.5 THz: New set of rotational and dipole parameters, first THz self-broadening measurements

NASA Astrophysics Data System (ADS)

Bray, Cédric; Cuisset, Arnaud; Hindle, Francis; Bocquet, Robin; Mouret, Gaël; Drouin, Brian J.

2017-03-01

Several previously unmeasured transitions of 12CH3D have been recorded by a terahertz photomixing continuous-wave spectrometer up to QR(10) branch at 2.5 THz. An improved set of rotational constants has been obtained utilizing a THz frequency metrology based on a frequency comb that achieved an averaged frequency position better than 150 kHz on more than fifty ground-state transitions. A detailed analysis of the measured line intensities was undertaken using the multispectrum fitting program and has resulted in a determination of new dipole moment parameters. Measurements at different pressures of the QR(7) transitions provide the first determination of self-broadening coefficients from pure rotational CH3D lines. The THz rotational measurements are consistent with IR rovibrational data but no significant vibrational dependence of self-broadening coefficient may be observed by comparison.

Spectral broadening measurement of the lower hybrid waves during long pulse operation in Tore Supra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger-By, G.; Decampy, J.; Goniche, M.

2014-02-12

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 frequencymore » 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 × 10{sup 19} 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.« less

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.

X-ray magnetic circular dichroism measured at the Fe K-edge with a reduced intrinsic broadening: x-ray absorption spectroscopy versus resonant inelastic x-ray scattering measurements

NASA Astrophysics Data System (ADS)

Juhin, Amélie; Sainctavit, Philippe; Ollefs, Katharina; Sikora, Marcin; Filipponi, Adriano; Glatzel, Pieter; Wilhelm, Fabrice; Rogalev, Andrei

2016-12-01

X-ray magnetic circular dichroism is measured at the Fe K pre-edge in yttrium iron garnet using two different procedures that allow reducing the intrinsic broadening due to the 1s corehole lifetime. First, deconvolution of XMCD data measured in total fluorescence yield (TFY) with an extremely high signal-to-noise ratio enables a factor of 2.4 to be gained in the XMCD intensity. Ligand field multiplet calculations performed with different values of intrinsic broadening show that deconvolving such high quality XMCD data is similar to reducing the lifetime broadening from a 1s corehole to a 2p corehole. Second, MCD is measured by resonant inelastic x-ray scattering spectroscopy as a function of incident energy and emission energy. Selection of a fixed emission energy, instead of using the TFY, allows enhancing the MCD intensity up to a factor of  ˜4.7. However, this significantly changes the spectral shape of the XMCD signal, which cannot be interpreted any more as an absorption spectrum.

Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic turbulence and tangled molecular clouds

NASA Astrophysics Data System (ADS)

Hacar, A.; Alves, J.; Burkert, A.; Goldsmith, P.

2016-06-01

Context. Since their first detection in the interestellar medium, (sub-)millimeter line observations of different CO isotopic variants have routinely been employed to characterize the kinematic properties of the gas in molecular clouds. Many of these lines exhibit broad linewidths that greatly exceed the thermal broadening expected for the low temperatures found within these objects. These observed suprathermal CO linewidths are assumed to originate from unresolved supersonic motions inside clouds. Aims: The lowest rotational J transitions of some of the most abundant CO isotopologues, 12CO and 13CO, are found to present large optical depths. In addition to well-known line saturation effects, these large opacities present a non-negligible contribution to their observed linewidths. Typically overlooked in the literature, in this paper we aim to quantify the impact of these opacity broadening effects on the current interpretation of the CO suprathermal line profiles. Methods: Combining large-scale observations and LTE modeling of the ground J = 1-0 transitions of the main 12CO, 13CO, C18O isotopologues, we have investigated the correlation of the observed linewidths as a function of the line opacity in different regions of the Taurus molecular cloud. Results: Without any additional contributions to the gas velocity field, a large fraction of the apparently supersonic (ℳ ~ 2-3) linewidths measured in both 12CO and 13CO (J = 1-0) lines can be explained by the saturation of their corresponding sonic-like, optically thin C18O counterparts assuming standard isotopic fractionation. Combined with the presence of multiple components detected in some of our C18O spectra, these opacity effects also seem to be responsible for most of the highly supersonic linewidths (ℳ > 8-10) detected in some of the broadest 12CO and 13CO spectra in Taurus. Conclusions: Our results demonstrate that most of the suprathermal 12CO and 13CO linewidths reported in nearby clouds like Taurus

Measurements of the electric field of zero-point optical phonons in GaAs quantum wells support the Urbach rule for zero-temperature lifetime broadening.

PubMed

Bhattacharya, Rupak; Mondal, Richarj; Khatua, Pradip; Rudra, Alok; Kapon, Eli; Malzer, Stefan; Döhler, Gottfried; Pal, Bipul; Bansal, Bhavtosh

2015-01-30

We study a specific type of lifetime broadening resulting in the well-known exponential "Urbach tail" density of states within the energy gap of an insulator. After establishing the frequency and temperature dependence of the Urbach edge in GaAs quantum wells, we show that the broadening due to the zero-point optical phonons is the fundamental limit to the Urbach slope in high-quality samples. In rough analogy with Welton's heuristic interpretation of the Lamb shift, the zero-temperature contribution to the Urbach slope can be thought of as arising from the electric field of the zero-point longitudinal-optical phonons. The value of this electric field is experimentally measured to be 3  kV cm-1, in excellent agreement with the theoretical estimate.

Correlation of the antimicrobial activity of salicylaldehydes with broadening of the NMR signal of the hydroxyl proton. Possible involvement of proton exchange processes in the antimicrobial activity.

PubMed

Elo, Hannu; Kuure, Matti; Pelttari, Eila

2015-03-06

Certain substituted salicylaldehydes are potent antibacterial and antifungal agents and some of them merit consideration as potential chemotherapeutic agents against Candida infections, but their mechanism of action has remained obscure. We report here a distinct correlation between broadening of the NMR signal of the hydroxyl proton of salicylaldehydes and their activity against several types of bacteria and fungi. When proton NMR spectra of the compounds were determined using hexadeuterodimethylsulfoxide as solvent and the height of the OH proton signal was measured, using the signal of the aldehyde proton as an internal standard, it was discovered that a prerequisite of potent antimicrobial activity is that the proton signal is either unobservable or relatively very low, i.e. that it is extremely broadened. Thus, none of the congeners whose OH proton signal was high were potent antimicrobial agents. Some congeners that gave a very low OH signal were, however, essentially inactive against the microbes, indicating that although drastic broadening of the OH signal appears to be a prerequisite, also other (so far unknown) factors are needed for high antimicrobial activity. Because broadening of the hydroxyl proton signal is related to the speed of the proton exchange process(es) involving that proton, proton exchange may be involved in the mechanism of action of the compounds. Further studies are needed to analyze the relative importance of different factors (such as electronic effects, strength of the internal hydrogen bond, co-planarity of the ring and the formyl group) that determine the rates of those processes. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Homogeneous and inhomogeneous broadenings and the Voigt line shapes in the phase-resolved and intensity sum-frequency generation vibrational spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Shunli; Fu, Li; Gan, Wei

2016-01-21

In this report we show that the ability to measure the sub-1 cm -1 resolution phase-resolved and intensity high-resolution broadband sum frequency generation vibrational spectra (HR-BB-SFG-VS) of the –CN stretch vibration of the Langmuir-Blodgett (LB) monolayer of the 4-n-octyl-4’-cyanobiphenyl (8CB) on the z-cut α-quartz surface allows for the first time the direct comparison and understanding of the homogeneous and inhomogeneous broadenings in the imaginary and intensity SFG vibrational spectral lineshapes in detail. The difference of the full width at half maxima (FWHM) of the imaginary and intensity SFG-VS spectra of the same vibrational mode is the signature of the Voigtmore » lineshape and it measures the relative contribution to the overall lineshape from the homogeneous and inhomogeneous broadenings in SFG vibrational spectra. From the phase-resolved and intensity spectra, we found that the FWHM of the 2238.00 ±0.02 cm -1 peak in the phase-resolved imaginary and intensity spectra is 19.2 ± 0.2 cm -1 and 21.6 ± 0.4 cm -1, respectively, for the –CN group of the 8CB LB monolayer on the z-cut α-quartz crystal surface. The FWHM width difference of 2.4 cm -1 agrees quantitatively with a Voigt lineshape with a homogeneous broadening half width of Γ = 5.29 ± 0.08 cm -1 and a inhomogeneous standard derivation width Δω = 5.42 ± 0.07 cm -1. These results shed new lights on the understanding and interpretation of the lineshapes of both the phase-resolved and the intensity SFG vibrational spectra, as well as other incoherent and coherent spectroscopic techniques in general.« less

Homogeneous and inhomogeneous broadenings and the Voigt line shapes in the phase-resolved and intensity sum-frequency generation vibrational spectroscopy.

PubMed

Chen, Shun-Li; Fu, Li; Gan, Wei; Wang, Hong-Fei

2016-01-21

In this report, we show that the ability to measure the sub-1 cm(-1) resolution phase-resolved and intensity high-resolution broadband sum frequency generation vibrational spectra of the -CN stretch vibration of the Langmuir-Blodgett (LB) monolayer of the 4-n-octyl-4'-cyanobiphenyl (8CB) on the z-cut α-quartz surface allows the direct comparison and understanding of the homogeneous and inhomogeneous broadenings in the imaginary and intensity SFG vibrational spectral line shapes in detail. The difference of the full width at half maximum (FWHM) of the imaginary and intensity sum-frequency generation vibrational spectroscopy spectra of the same vibrational mode is the signature of the Voigt line shape and it measures the relative contribution to the overall line shape from the homogeneous and inhomogeneous broadenings in SFG vibrational spectra. From the phase-resolved and intensity spectra, we found that the FWHM of the 2238.00 ± 0.02 cm(-1) peak in the phase-resolved imaginary and intensity spectra is 19.2 ± 0.2 cm(-1) and 21.6 ± 0.4 cm(-1), respectively, for the -CN group of the 8CB LB monolayer on the z-cut α-quartz crystal surface. The FWHM width difference of 2.4 cm(-1) agrees quantitatively with a Voigt line shape with a homogeneous broadening half width of Γ = 5.29 ± 0.08 cm(-1) and an inhomogeneous standard derivation width Δω = 5.42 ± 0.07 cm(-1). These results shed new lights on the understanding and interpretation of the line shapes of both the phase-resolved and the intensity SFG vibrational spectra, as well as other incoherent and coherent spectroscopic techniques in general.

A measurement of the width and shift of the Fe I 3719.94 A line broadened by helium. [for stellar atmosphere studies

NASA Technical Reports Server (NTRS)

Driver, R. D.; Lombardi, G.

1977-01-01

Results are reported for measurements of the widths and shifts of the overlapping helium-broadened profiles of the Fe I absorption lines at 3719.94 and 3722.56 A, which were performed in a ballistic piston compressor using a saturated solution of FeCl3 in ethanol. It is found that at 4000 K, the 3719.94-A line has a gamma/n (FWHM) value of approximately 5.2 billionths rad/sec per cu cm, the blue shift of this line corresponds to a beta/n value of about 0.49 billionth rad/sec per cu cm, and the 3722.56-A line has the same values. These results are compared with previous experimental determinations and with theoretical calculations of neutral-line broadening for the Fe I lines. The significance of these measurements with respect to the solar spectrum and cool DG white dwarfs is discussed.

Energy broadening in electron beams: A comparison of existing theories and Monte Carlo simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansen, G.H.; Groves, T.R.; Stickel, W.

1985-01-01

Different theories on the Boersch effect are applied to a simple beam geometry with one crossover in drift space.The results are compared with each other, with Monte Carlo simulations, and with the experiment. The most complete and accurate theory is given by van Leeuwen and Jansen. This theory predicts energy spreads within 10% of the Monte Carlo results for operating conditions usually given in systems with thermionic emission sources. No comprehensive theory, however, of energy broadening in electron guns has yet been presented. Nevertheless, the theory of van Leeuwen and Jansen was found to predict the experimental values by trendmore » and within a factor of 2.« less

Is it only the regulatory status? Broadening the debate on cisgenic plants.

PubMed

van Hove, Lilian; Gillund, Frøydis

2017-01-01

In current debates on emerging technologies for plant breeding in Europe, much attention has been given to the regulatory status of these techniques and their public acceptance. At present, both genetically modified plants with cisgenic approaches-using genes from crossable species-as well as transgenic approaches-using genes from different species-fall under GMO regulation in the EU and both are mandatorily labelled as GMOs. Researchers involved in the early development of cisgenic GM plants convey the message that the potential use and acceptance of cisgenic approaches will be seriously hindered if GMO regulations are not adjusted. Although the similar treatment and labelling of transgenic and cisgenic plants may be a legitimate concern for the marketability of a cisgenic GM plant, there are concerns around their commercialization that reach beyond the current focus on (de)regulation. In this paper, we will use the development of the cisgenic GM potato that aims to overcome 'late blight'-the most devastating potato disease worldwide-as a case to argue that it is important to recognize, reflect and respond to broader concerns than the dominant focus on the regulatory 'burden' and consumer acceptance. Based on insights we gained from discussing this case with diverse stakeholders within the agricultural sector and potato production in Norway during a series of workshops, we elaborate on additional issues such as the (technical) solution offered; different understandings of the late blight problem; the durability of the potato plant resistance; and patenting and ownership. Hence, this paper contributes to empirical knowledge on stakeholder perspectives on emerging plant breeding technologies, underscoring the importance to broaden the scope of the debate on the opportunities and challenges of agricultural biotechnologies, such as cisgenic GM plants. The paper offers policy-relevant input to ongoing efforts to broaden the scope of risk assessments of agricultural

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.

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.

Study of Rubber Composites with Positron Doppler Broadening Spectroscopy: Consideration of Counting Rate

NASA Astrophysics Data System (ADS)

Yang, Chun; Quarles, C. A.

2007-10-01

We have used positron Doppler Broadening Spectroscopy (DBS) to investigate the uniformity of rubber-carbon black composite samples. The amount of carbon black added to a rubber sample is characterized by phr, the number of grams of carbon black per hundred grams of rubber. Typical concentrations in rubber tires are 50 phr. It has been shown that the S parameter measured by DBS depends on the phr of the sample, so the variation in carbon black concentration can be easily measured to 0.5 phr. In doing the experiments we observed a dependence of the S parameter on small variation in the counting rate or deadtime. By carefully calibrating this deadtime correction we can significantly reduce the experimental run time and thus make faster determination of the uniformity of extended samples.

Conjugating precision and acquisition time in a Doppler broadening regime by interleaved frequency-agile rapid-scanning cavity ring-down spectroscopy.

PubMed

Gotti, Riccardo; Gatti, Davide; Masłowski, Piotr; Lamperti, Marco; Belmonte, Michele; Laporta, Paolo; Marangoni, Marco

2017-10-07

We propose a novel approach to cavity-ring-down-spectroscopy (CRDS) in which spectra acquired with a frequency-agile rapid-scanning (FARS) scheme, i.e., with a laser sideband stepped across the modes of a high-finesse cavity, are interleaved with one another by a sub-millisecond readjustment of the cavity length. This brings to time acquisitions below 20 s for few-GHz-wide spectra composed of a very high number of spectral points, typically 3200. Thanks to the signal-to-noise ratio easily in excess of 10 000, each FARS-CRDS spectrum is shown to be sufficient to determine the line-centre frequency of a Doppler broadened line with a precision of 2 parts over 10 11 , thus very close to that of sub-Doppler regimes and in a few-seconds time scale. The referencing of the probe laser to a frequency comb provides absolute accuracy and long-term reproducibility to the spectrometer and makes it a powerful tool for precision spectroscopy and line-shape analysis. The experimental approach is discussed in detail together with experimental precision and accuracy tests on the (30 012) ← (00 001) P12e line of CO 2 at ∼1.57 μm.

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).

Broadening of Analyte Streams due to a Transverse Pressure Gradient in Free-Flow Isoelectric Focusing

PubMed Central

Dutta, Debashis

2017-01-01

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. PMID:28081900

Cavity ring-down spectroscopy of Doppler-broadened absorption line with sub-MHz absolute frequency accuracy.

PubMed

Cheng, C-F; Sun, Y R; Pan, H; Lu, Y; Li, X-F; Wang, J; Liu, A-W; Hu, S-M

2012-04-23

A continuous-wave cavity ring-down spectrometer has been built for precise determination of absolute frequencies of Doppler-broadened absorption lines. Using a thermo-stabilized Fabry-Pérot interferometer and Rb frequency references at the 780 nm and 795 nm, 0.1 - 0.6 MHz absolute frequency accuracy has been achieved in the 775-800 nm region. A water absorption line at 12579 cm(-1) is studied to test the performance of the spectrometer. The line position at zero-pressure limit is determined with an uncertainty of 0.3 MHz (relative accuracy of 0.8 × 10(-9)). © 2012 Optical Society of America

The Science Exchange Program - A Proposal.

ERIC Educational Resources Information Center

Klausen, James

An exchange program is described in which two groups of high school science students, one from Long Island, New York, and one from upstate New York, visited each other's school districts for three days to broaden their experiences with different physical and geological surroundings. The inland group of students was exposed to marine geology and…

Interstellar Broadening of Images in the Gravitational Lens Pks 1830-211

NASA Technical Reports Server (NTRS)

Jones, D. L.; Preston, R. A.; Murphy, D. W.; Jauncey, D. L.; Reynolds, J. E.; Tzioumis, A. K.; King, E. A.; McCulloch, P. M.; Lovell, J. E. J.; Costa, M. E.

1996-01-01

The remarkably strong radio gravitational lens PKS 1830-211 consists of a one arcsecond diameter Einstein ring with two bright compact (milliarcsecond) components located on opposite sides of the ring. We have obtained 22 GHz VLBA data on this source to determine the intrinsic angular sizes of the compact components. Previous VLBI observations at lower frequencies indicate that the brightness temperatures of these components are significantly lower than 10(exp 10) K (Jauncey, et al. 1991), less than is typical for compact synchrotron radio sources and less than is implied by the short timescales of flux density variations. A possible explanation is that interstellar scattering is broadening the apparent angular size of the source and thereby reducing the observed brightness temperature. Our VLBA data support this hypothesis. At 22 GHz the measured brightness temperature is at least 10(exp 11) K, and the deconvolved 2 size of the core in the southwest compact component is proportional to upsilon(sup -2) between 1.7 and 22 GHz. VLBI observations at still higher frequencies should be unaffected by interstellar scattering.

Strategies for Broadening Participation in the Geosciences: Lessons Learned From the UCAR-SOARSr Program

NASA Astrophysics Data System (ADS)

Pandya, R. E.

2004-12-01

Broadening participation in the geosciences will advance our research, enhance our education and training, and improve our ability to meet societal needs. By attracting more diverse students, we will be better postioned to provide all our students the increasingly necessary and relevant experience of working in diverse teams. Because some traditionally underrepresented groups, particularly Latinos & Hispanics, are growing much faster than the population as a whole, broader participation will enlarge the pool of talented individuals contributing to the next generation of research. Finally the geosciences will be more effective and credible when the diversity of our nation is reflected in our workforce, especially as civic discourse includes more and more complex decisions about society's interactions with the Earth and its resources. The Significant Opportunities in Atmospheric Research and Science (SOARS) seeks to broaden participation in geosciences by helping undergraduate students successfully transition to graduate programs in the atmospheric and related sciences. SOARS combines multiple research experiences, multifaceted mentoring, an encouraging community, and financial support to help students enter and succeed in graduate school. A central feature of the SOARS program is a ten-week summer immersion program in which protégés (SOARS participants) conduct scientific research at the National Center for Atmospheric Research (NCAR) or at laboratories of SOARS sponsors. During this summer research experience, SOARS protégés are supported by up to four mentors: a science research mentor, a writing mentor, a community mentor, and a peer mentor. SOARS protégés collaborate with their mentors to perform original research, prepare scientific papers, and present their research at a colloquium. SOARS also provides extensive leadership and communication training; support for conference presentations and for graduate school; and a strong scholarly community that

Local Talent: By Tapping into the Resources Just outside Their School Walls, Music Teachers Can Help Broaden Their Students' Horizons

ERIC Educational Resources Information Center

Randall, Mac

2009-01-01

Many music teachers across the country have learned how beneficial it can be to tap into the communities around them. The author discusses how music teachers can help broaden their students' horizons by tapping into the resources just outside their school walls. One way is by employing local talents. Another is to put an ad in nearby music stores,…

Broadening perspectives on trauma and recovery: a socio-interpersonal view of PTSD†

PubMed Central

Maercker, Andreas; Hecker, Tobias

2016-01-01

Posttraumatic stress disorder (PTSD) is one of the very few mental disorders that requires by definition an environmental context—a traumatic event or events—as a precondition for diagnosis. Both trauma sequelae and recovery always occur in the context of social–interpersonal contexts, for example, in interaction with a partner, family, the community, and the society. The present paper elaborates and extends the social–interpersonal framework model of PTSD. This was developed to complement other intrapersonally focused models of PTSD, which emphasize alterations in an individual's memory, cognitions, or neurobiology. Four primary reasons for broadening the perspective from the individual to the interpersonal–societal contexts are discussed. The three layers of the model (social affects, close relationships, and culture and society) are outlined. We further discuss additional insights and benefits of the social–interpersonal perspective for the growing field of research regarding resilience after traumatic experiences. The paper closes with an outlook on therapy approaches and interventions considering this broader social–interpersonal perspective on PTSD. PMID:26996533

Self-pulsing in a 2 km single-mode fiber with the seed source broadened via WNS phase modulation

NASA Astrophysics Data System (ADS)

Zha, Congwen; Sun, Yinhong; Wang, Yanshan; Li, Tenglong; Peng, Wanjing; Ma, Yi; Zhang, Kai

2018-03-01

The seed source with spectral linewidth broadening via phase modulation is potential to achieve the higher output power with effective SBS suppression. However, self-pulsing from the amplifier output is harmful. In this work, we study the self-pulsing characteristics in a long single-mode fiber with lower self-pulsing threshold instead of the high power amplifier. We provide a powerful experimental support for the self-pulsing mechanism in high-power narrow-linewidth fiber lasers, which is important for further output power scaling.

Nine Proposals for a More Competitive TIAA-CREF.

ERIC Educational Resources Information Center

Harrigan, John J.

1994-01-01

Nine recommendations are offered for making the Teachers' Insurance Annuity Association (TIAA) and College Retirement Equities Fund (CREF) more attractive and competitive retirement investment vehicles for college faculty. They include broadening of account choice, fund transfer and management options, and counseling services. (MSE)

Multispectrum analysis of air-broadened spectra in the ν3 Q branch of 12CH4

NASA Astrophysics Data System (ADS)

Devi, V. Malathy; Benner, D. Chris; Gamache, Robert R.; Tran, H.; Smith, Mary Ann H.; Sams, Robert L.

2018-02-01

We report experimental measurements of spectral line shape parameters (air-broadened width, shift, and line mixing coefficients) for several transitions in the ν3 Q branch of methane in the 3000-3023 cm-1 region. 13 high-resolution, room temperature laboratory spectra of pure methane and air-broadened methane recorded with two different Fourier transform spectrometers are fitted. 12 of these spectra were acquired at 0.01 cm-1 resolution with the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak, and one higher-resolution (∼0.0011 cm-1) low pressure methane spectrum was obtained with the Bruker IFS-120HR FTS at the Pacific Northwest National Laboratory, in Richland, Washington. All the spectra were obtained using high purity natural samples of CH4 and lean mixtures of the same natural CH4 in dry air. For the 12 spectra recorded at Kitt Peak, three different absorption cells (L = 5, 25 and 150 cm) were used while the methane spectrum at PNNL was obtained using a 19.95 cm long absorption cell. For the analysis, an interactive multispectrum nonlinear least squares fitting software was employed where all the 13 spectra were fitted simultaneously. An accurate and self-consistent set of line parameters were determined by constraining a few of those for severely blended transitions. Line mixing was measured for 14 transition pairs for the CH4-air collision system. A constant speed dependence parameter, consistent with measured speed dependence values obtained in other methane bands, was applied to all the transitions included in the fitted region. The present measurements are compared to values reported in the literature.

Localized spiraling plasma ejection contributing the ion-flux broadening in the detached linear plasma

NASA Astrophysics Data System (ADS)

Tanaka, H.; Takeyama, K.; Yoshikawa, M.; Kajita, S.; Ohno, N.; Hayashi, Y.

2018-07-01

We have performed multipoint measurements with segmented electrodes and a microwave interferometer in the linear plasma device NAGDIS-II, in order to reveal cross-field motion and axial localization of the enhanced radial transport in the detached plasma. By changing the neutral pressure successively and applying several statistical analysis techniques, it was clarified that there is axially localized ion flux broadening accompanying an enhanced plasma ejection from the center with radially elongated spiraling structure. The spiraling plasma ejection accompanies the m = 0 mode drop near the center with the similar time scale. Further, such behavior composed of f > 1 kHz fluctuations is modulated by several-hundred-hertz fluctuation with m = 0. This cross-field transport causes non-negligible effect for the reduction of the ion flux peak in the detached plasma.

Creation of problem-dependent Doppler-broadened cross sections in the KENO Monte Carlo code

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

Line intensities and temperature-dependent line broadening coefficients of Q-branch transitions in the v2 band of ammonia near 10.4 μm

NASA Astrophysics Data System (ADS)

Sur, Ritobrata; Spearrin, R. Mitchell; Peng, Wen Y.; Strand, Christopher L.; Jeffries, Jay B.; Enns, Gregory M.; Hanson, Ronald K.

2016-05-01

We report measured line intensities and temperature-dependent broadening coefficients of NH3 with Ar, N2, O2, CO2, H2O, and NH3 for nine sQ(J,K) transitions in the ν2 fundamental band in the frequency range 961.5-967.5 cm-1. This spectral region was chosen due to the strong NH3 absorption strength and lack of spectral interference from H2O and CO2 for laser-based sensing applications. Spectroscopic parameters were determined by multi-line fitting using Voigt lineshapes of absorption spectra measured with two quantum cascade lasers in thermodynamically-controlled optical cells. The temperature dependence of broadening was measured over a range of temperatures between 300 and 600 K. These measurements aid the development of mid-infrared NH3 sensors for a broad range of gas mixtures and at elevated temperatures.

Optical properties of an inhomogeneously broadened ΛV-system with multiple excited states

NASA Astrophysics Data System (ADS)

Kaur, Paramjit; Bharti, Vineet; Wasan, Ajay

2014-09-01

We present a theoretical model using a density matrix approach to show the influence of multiple excited states on the optical properties of an inhomogeneously broadened ?V-system of the ?Rb D2 line. These closely spaced multiple excited states cause asymmetry in absorption and dispersion profiles. We observe the reduced absorption profiles, due to dressed state interactions of the applied electromagnetic fields, which results the Mollow sideband-like transparency windows. In a room temperature vapor, we obtain a narrow enhanced absorption and steep positive dispersion at the line center when the strengths of control and pump fields are equal. Here, we show how the probe transmittance varies when it passes through the atomic medium. We also discuss the transient behavior of our system which agrees well with the corresponding absorption and dispersion profiles. This study has potential applications in controllability of group velocity, and for optical and quantum information processing.

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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

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.

Electron Stark Broadening Database for Atomic N, O, and C Lines

NASA Technical Reports Server (NTRS)

Liu, Yen; Yao, Winifred M.; Wray, Alan A.; Carbon, Duane F.

2012-01-01

A database for efficiently computing the electron Stark broadening line widths for atomic N, O, and C lines is constructed. The line width is expressed in terms of the electron number density and electronatom scattering cross sections based on the Baranger impact theory. The state-to-state cross sections are computed using the semiclassical approximation, in which the atom is treated quantum mechanically whereas the motion of the free electron follows a classical trajectory. These state-to-state cross sections are calculated based on newly compiled line lists. Each atomic line list consists of a careful merger of NIST, Vanderbilt, and TOPbase line datasets from wavelength 50 nm to 50 micrometers covering the VUV to IR spectral regions. There are over 10,000 lines in each atomic line list. The widths for each line are computed at 13 electron temperatures between 1,000 K 50,000 K. A linear least squares method using a four-term fractional power series is then employed to obtain an analytical fit for each line-width variation as a function of the electron temperature. The maximum L2 error of the analytic fits for all lines in our line lists is about 5%.

Broadening of cloud droplet spectra through turbulent entrainment and eddy hopping

NASA Astrophysics Data System (ADS)

Abade, Gustavo; Grabowski, Wojciech; Pawlowska, Hanna

2017-11-01

This work discusses the effect of cloud turbulence and turbulent entrainment on the evolution of the cloud droplet-size spectrum. We simulate an ensemble of idealized turbulent cloud parcels that are subject to entrainment events, modeled as a random Poisson process. Entrainment events, subsequent turbulent mixing inside the parcel, supersaturation fluctuations, and the resulting stochastic droplet growth by condensation are simulated using a Monte Carlo scheme. Quantities characterizing the turbulence intensity, entrainment rate and the mean fraction of environmental air entrained in an event are specified as external parameters. Cloud microphysics is described by applying Lagrangian particles, the so-called superdroplets. They are either unactivated cloud condensation nuclei (CCN) or cloud droplets that form from activated CCN. The model accounts for the transport of environmental CCN into the cloud by the entraining eddies at the cloud edge. Turbulent mixing of the entrained dry air with cloudy air is described using a linear model. We show that turbulence plays an important role in aiding entrained CCN to activate, providing a source of small cloud droplets and thus broadening the droplet size distribution. Further simulation results will be reported at the meeting.

Measurements of Lorentz air-broadening coefficients and relative intensities in the H2O-16 pure rotational and nu2 bands from long horizontal path atmospheric spectra

NASA Technical Reports Server (NTRS)

Rinsland, Curtis P.; Smith, Mary Ann H.; Goldman, Aaron; Malathy Devi, V.

1991-01-01

Lorentz air-broadening coefficients and relative intensities have been measured for forty-three lines in the pure rotational band and twenty lines in the nu2 band of H2O-16 between 800 and 1150/cm. The results were derived from analysis of nine 0.017/cm-resolution atmospheric absorption spectra recorded over horizontal paths of 0.5-1.5 km with the McMath Fourier transform spectrometer and main solar telescope operated on Kitt Peak by the National Solar Observatory. A nonlinear least-squares spectral fitting technique was used in the spectral analysis. The results are compared with previous measurements and calculations. In most cases, the measured pressure-broadening coefficients and intensities are significantly different from the values in the 1986 HITRAN line parameters compilation.

Measurements of the broadening and shift parameters of the water vapor spectral lines in the 10,100-10,800 cm-1 region induced by pressure of carbon dioxide

NASA Astrophysics Data System (ADS)

Borkov, Yu. G.; Petrova, T. M.; Solodov, A. M.; Solodov, A. A.

2018-02-01

The absorption spectra of a mixture of H2O with CO2 at different partial pressures of CO2 have been recorded at room temperature in the 10,100-10,800 cm-1 region using a Bruker IFS 125 HR FTIR spectrometer. The multispectrum fitting procedure has been applied to these spectra to recover the broadening and shift parameters of the water vapor spectral lines. To obtain the spectral lines parameters two models of the line shape were used: the Voigt profile and the quadratic speed-dependent Voigt profile. The CO2 pressure induced broadening and shift coefficients for 168 spectral lines with rather large values of the signal to noise ratio have been measured.

A far wing line shape theory and its application to the foreign-broadened water continuum absorption. III

NASA Technical Reports Server (NTRS)

Ma, Q.; Tipping, R. H.

1992-01-01

The far wing line shape theory developed previously and applied to the calculation of the continuum absorption of pure water vapor is extended to foreign-broadened continua. Explicit results are presented for H2O-N2 and H2O-CO2 in the frequency range from 0 to 10,000/cm. For H2O-N2 the positive and negative resonant frequency average line shape functions and absorption coefficients are computed for a number of temperatures between 296 and 430 K for comparison with available laboratory data. In general the agreement is very good.

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).

Rotational quenching of H2CO by molecular hydrogen: cross-sections, rates and pressure broadening

NASA Astrophysics Data System (ADS)

Wiesenfeld, L.; Faure, A.

2013-07-01

We compute the rotational quenching rates of the first 81 rotational levels of ortho- and para-H2CO in collision with ortho- and para-H2, for a temperature range of 10-300 K. We make use of the quantum close-coupling and coupled-state scattering methods combined with the high accuracy potential energy surface of Troscompt et al. Rates are significantly different from the scaled rates of H2CO in collision with He; consequently, critical densities are notably lower. We compare a full close-coupling computation of pressure broadening cross-sections with experimental data and show that our results are compatible with the low-temperature measurements of Mengel & De Lucia, for a spin temperature of H2 around 50 K.

Velocity selection in a Doppler-broadened ensemble of atoms interacting with a monochromatic laser beam

NASA Astrophysics Data System (ADS)

Hughes, Ifan G.

2018-03-01

There is extensive use of monochromatic lasers to select atoms with a narrow range of velocities in many atomic physics experiments. For the commonplace situation of the inhomogeneous Doppler-broadened (Gaussian) linewidth exceeding the homogeneous (Lorentzian) natural linewidth by typically two orders of magnitude, a substantial narrowing of the velocity class of atoms interacting with the light can be achieved. However, this is not always the case, and here we show that for a certain parameter regime there is essentially no selection - all of the atoms interact with the light in accordance with the velocity probability density. An explanation of this effect is provided, emphasizing the importance of the long tail of the constituent Lorentzian distribution in a Voigt profile.

[Calculating the stark broadening of welding arc spectra by Fourier transform method].

PubMed

Pan, Cheng-Gang; Hua, Xue-Ming; Zhang, Wang; Li, Fang; Xiao, Xiao

2012-07-01

It's the most effective and accurate method to calculate the electronic density of plasma by using the Stark width of the plasma spectrum. However, it's difficult to separate Stark width from the composite spectrum linear produced by several mechanisms. In the present paper, Fourier transform was used to separate the Lorentz linear from the spectrum observed, thus to get the accurate Stark width. And we calculated the distribution of the TIG welding arc plasma. This method does not need to measure arc temperature accurately, to measure the width of the plasma spectrum broadened by instrument, and has the function to reject the noise data. The results show that, on the axis, the electron density of TIG welding arc decreases with the distance from tungsten increasing, and changes from 1.21 X 10(17) cm(-3) to 1.58 x 10(17) cm(-3); in the radial, the electron density decreases with the distance from axis increasing, and near the tungsten zone the biggest electronic density is off axis.

From the NSF: The National Science Foundation's Investments in Broadening Participation in Science, Technology, Engineering, and Mathematics Education through Research and Capacity Building

ERIC Educational Resources Information Center

James, Sylvia M.; Singer, Susan R.

2016-01-01

The National Science Foundation (NSF) has a long history of investment in broadening participation (BP) in science, technology, engineering, and mathematics (STEM) education. A review of past NSF BP efforts provides insights into how the portfolio of programs and activities has evolved and the broad array of innovative strategies that has been…

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.

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

DOE PAGES

Moody, Galan; Dass, Chandriker Kavir; Hao, Kai; ...

2015-09-18

In this paper, the band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe 2). The homogeneous linewidthmore » is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton–exciton and exciton–phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here—strong many-body effects and intrinsically rapid radiative recombination—are expected to be ubiquitous in atomically thin semiconductors.« less

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

PubMed Central

Moody, Galan; Kavir Dass, Chandriker; Hao, Kai; Chen, Chang-Hsiao; Li, Lain-Jong; Singh, Akshay; Tran, Kha; Clark, Genevieve; Xu, Xiaodong; Berghäuser, Gunnar; Malic, Ermin; Knorr, Andreas; Li, Xiaoqin

2015-01-01

The band-edge optical response of transition metal dichalcogenides, an emerging class of atomically thin semiconductors, is dominated by tightly bound excitons localized at the corners of the Brillouin zone (valley excitons). A fundamental yet unknown property of valley excitons in these materials is the intrinsic homogeneous linewidth, which reflects irreversible quantum dissipation arising from system (exciton) and bath (vacuum and other quasiparticles) interactions and determines the timescale during which excitons can be coherently manipulated. Here we use optical two-dimensional Fourier transform spectroscopy to measure the exciton homogeneous linewidth in monolayer tungsten diselenide (WSe2). The homogeneous linewidth is found to be nearly two orders of magnitude narrower than the inhomogeneous width at low temperatures. We evaluate quantitatively the role of exciton–exciton and exciton–phonon interactions and population relaxation as linewidth broadening mechanisms. The key insights reported here—strong many-body effects and intrinsically rapid radiative recombination—are expected to be ubiquitous in atomically thin semiconductors. PMID:26382305

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)

Multispectrum analysis of air-broadened spectra in the ν 3 Q branch of 12CH4

DOE PAGES

Devi, V. Malathy; Benner, D. Chris; Gamache, Robert R.; ...

2017-12-06

In this paper, we report experimental measurements of spectral line shape parameters (air-broadened width, shift, and line mixing coefficients) for several transitions in the ν 3 Q branch of methane in the 3000–3023 cm -1 region. 13 high-resolution, room temperature laboratory spectra of pure methane and air-broadened methane recorded with two different Fourier transform spectrometers are fitted. 12 of these spectra were acquired at 0.01 cm -1 resolution with the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak, and one higher-resolution (~0.0011 cm-1) low pressure methane spectrum was obtained with the Bruker IFS-120HR FTS at the Pacific Northwestmore » National Laboratory, in Richland, Washington. All the spectra were obtained using high purity natural samples of CH 4 and lean mixtures of the same natural CH 4 in dry air. For the 12 spectra recorded at Kitt Peak, three different absorption cells (L= 5, 25 and 150 cm) were used while the methane spectrum at PNNL was obtained using a 19.95 cm long absorption cell. For the analysis, an interactive multispectrum nonlinear least squares fitting software was employed where all the 13 spectra were fitted simultaneously. An accurate and self-consistent set of line parameters were determined by constraining a few of those for severely blended transitions. Line mixing was measured for fourteen transition pairs for the CH 4-air collision system. Lastly, a constant speed dependence parameter, consistent with measured speed dependence values obtained in other methane bands, was applied to all the transitions included in the fitted region. The present measurements are compared to values reported in the literature.« less

Line parameters for CO2- and self-broadening in the ν3 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.

2017-12-01

Pressure-broadened line shape parameters of transitions in the ν3 band of HDO (ν0 = 3707.4 cm-1) were measured from spectra of HDO and mixtures of HDO and CO2 for application to accurate retrievals of HDO abundances and D/H ratios for CO2-rich planetary atmospheres of Mars and Venus. A few calculated line lists have recently been published on HDO-CO2 line shapes and their temperature dependences, but the present study represents the first laboratory measurements of those parameters in the ν3 band; Measurements for nearly 100 transitions in the ν3 band have been made. Room temperature measurements of self-broadened width and shift coefficients for all of these transitions, line mixing via off-diagonal relaxation matrix element coefficients and quadratic speed dependence parameter were measured for the majority of these transitions. All these measurements were made by simultaneously fitting eleven high-resolution spectra of HDO and HDO-CO2 mixtures at various temperatures and pressures recorded with the Bruker Fourier transform spectrometer at the Jet Propulsion Laboratory. Two specially built coolable absorption cells with path lengths of 20.38 cm and 20.941 m were used to contain the sample mixtures. Multispectrum nonlinear least squares fitting algorithm was employed in the analysis. Calculations using the Modified Complex Robert-Bonamy formalism (MCRB) were made for the half-width coefficients, their temperature dependences and pressure shift coefficients for the HDO-CO2 and HDO-HDO collision systems. The calculations were made for all ν3 band transitions in the 1100-4100 cm-1 region on the HITRAN2012 database. Present measurements are compared with the MCRB calculations and other literature values.

Accurate measurements of the true column efficiency and of the instrument band broadening contributions in the presence of a chromatographic column.

PubMed

Gritti, Fabrice; Guiochon, Georges

2014-01-31

A rapid and simple validated experimental protocol is proposed for the accurate determination of the true intrinsic column efficiency and for that of the variance of the extra-column volume of the instrument used, the latter being obtained without requiring the removal of the chromatographic column from the HPLC system. This protocol was applied to 2.1mm×100mm columns packed with sub-3 (2.7μm Halo Peptide ES-C18) and sub-2μm (1.6μm prototype) core-shell particles. It was validated by observing the linear behavior of the plot of the apparent column plate height versus the reciprocal of (1+k')(2) for at least three homologous compounds, with a linear regression coefficient R(2) larger than 0.999. Irrespective of the contribution of the several, different instruments used to the total band broadening, the same column HETP value was obtained within 5%. This new protocol outperform the classical one in which the chromatographic column is replaced with a zero dead volume (ZDV) union connector to measure the extra-column volume variance, which is subtracted from the variance measured with the column to measure the intrinsic HETP. This protocol fails because it significantly underestimates the system volume variance. Copyright © 2013 Elsevier B.V. All rights reserved.

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

Analysis of Postdoctoral Training Outcomes That Broaden Participation in Science Careers

PubMed Central

Rybarczyk, Brian J.; Lerea, Leslie; Whittington, Dawayne; Dykstra, Linda

2016-01-01

Postdoctoral training is an optimal time to expand research skills, develop independence, and shape career trajectories, making this training period important to study in the context of career development. Seeding Postdoctoral Innovators in Research and Education (SPIRE) is a training program that balances research, teaching, and professional development. This study examines the factors that promote the transition of postdocs into academic careers and increase diversity in science, technology, engineering, and mathematics. Data indicate that SPIRE scholars (n = 77) transition into faculty positions at three times the national average with a greater proportion of underrepresented racial minorities (URMs) and females represented among SPIRE scholars. Logistic regression models indicate that significant predictors are the intended career track at the start of the postdoctoral training and the number of publications. Factors necessary for successful transition are teaching experience as independent instructors, professional development opportunities, and the experience of balancing teaching with research. Scholars’ continued commitment to increasing diversity in their faculty roles was demonstrated by their attainment of tenure-track positions at minority-serving institutions, continued mentorship of URMs, and engagement with diversity initiatives. These results suggest that a postdoctoral program structured to include research, teaching, and diversity inclusion facilitates attainment of desired academic positions with sustained impacts on broadening participation. PMID:27543634

Surface hopping with a manifold of electronic states. III. Transients, broadening, and the Marcus picture

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 yieldsmore » a useful starting point for capturing level broadening. For a simple such model, we find I-V curves that exhibit negative differential resistance.« less

Broadening of Cloud Droplet Size Distributions and Warm Rain Initiation Associated with Turbulence: An Overview

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Chunsong; Liu, Yangang; Niu, Shengjie

In the paper of warm clouds, there are many outstanding questions. Cloud droplet size distributions are much wider, and warm rain is initiated in a shorter time and with a shallower cloud depth than theoretical expectations. This review summarizes the studies related to the effects of turbulent fluctuations and turbulent entrainment-mixing on the broadening of droplet size distributions and warm rain initiation, including observational, laboratorial, numerical, and theoretical achievements. Particular attention is paid to studies by Chinese scientists since the 1950s, since most results have been published in Chinese. The review reveals that high-resolution observations and simulations, and laboratory experimentsmore » are needed because knowledge of the detailed physical processes involved in the effects of turbulence and entrainment-mixing on cloud microphysics still remains elusive.« less

Broadening of Cloud Droplet Size Distributions and Warm Rain Initiation Associated with Turbulence: An Overview

DOE PAGES

Lu, Chunsong; Liu, Yangang; Niu, Shengjie; ...

2017-10-12

In the paper of warm clouds, there are many outstanding questions. Cloud droplet size distributions are much wider, and warm rain is initiated in a shorter time and with a shallower cloud depth than theoretical expectations. This review summarizes the studies related to the effects of turbulent fluctuations and turbulent entrainment-mixing on the broadening of droplet size distributions and warm rain initiation, including observational, laboratorial, numerical, and theoretical achievements. Particular attention is paid to studies by Chinese scientists since the 1950s, since most results have been published in Chinese. The review reveals that high-resolution observations and simulations, and laboratory experimentsmore » are needed because knowledge of the detailed physical processes involved in the effects of turbulence and entrainment-mixing on cloud microphysics still remains elusive.« less

In-medium jet evolution: interplay between broadening and decoherence effects. The XXVth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

NASA Astrophysics Data System (ADS)

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

2016-12-01

The description of the modifications of the coherence pattern in a parton shower, in the presence of a QGP, has been actively addressed in recent studies. Among the several achievements, finite energy corrections, transverse momentum broadening due to medium interactions and interference effects between successive emissions have been extensively improved as they seem to be essential features for a correct description of the results obtained in heavy-ion collisions. In this work, based on the insights of our previous work [L. Apolinário, N. Armesto, J. G. Milhano, C. A. Salgado, Medium-induced gluon radiation and colour decoherence beyond the soft approximation, JHEP 1502 (2015) 119. arxiv:arXiv:1407.0599], we explore the physical interplay between broadening and decoherence, by generalising previous studies of medium-modifications of the antenna spectrum [Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, Antiangular Ordering of Gluon Radiation in QCD Media, Phys. Rev. Lett. 106 (2011) 122002. arxiv:arXiv:1009.2965, J. Casalderrey-Solana, E. Iancu, Interference effects in medium-induced gluon radiation, JHEP 08 (2011) 015. arxiv:arXiv:1105.1760, Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, The Radiation pattern of a QCD antenna in a dense medium, JHEP 10 (2012) 197. arxiv:arXiv:1205.5739] - so far restricted to the case where transverse motion is neglected. The result allow us to identify two quantities controlling the decoherence of a medium modified shower that can be used as building blocks for a successful future generation of jet quenching Monte Carlo simulators: a generalisation of the Δmed parameter of the works of [Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, Antiangular Ordering of Gluon Radiation in QCD Media, Phys. Rev. Lett. 106 (2011) 122002. arxiv:arXiv:1009.2965, Y. Mehtar-Tani, C. A. Salgado, K. Tywoniuk, The Radiation pattern of a QCD antenna in a dense medium, JHEP 10 (2012) 197. arxiv:arXiv:1205.5739] - that controls the interplay between the transverse

Using place-based concepts, multicultural lenses, and hands-on experience to broaden participation in the sciences for native youth

NASA Astrophysics Data System (ADS)

Flick, K. C.; Keepseagle, L.

2013-12-01

Broadening the participation of Native Americans in the geosciences is an important yet challenging goal. The perspectives of native and typically underserved populations can contribute to pushing the geosciences to address emerging scientific, social, and cultural issues that are relevant for questions geoscience fields ask, as well as their future applications. We will discuss the multicultural learning processes implemented in a sustainability and bioenergy education project which is centered in science and culture and characterized by cross-institutional partnerships. The Place-Based Opportunities for Sustainable Outcomes and High Hopes (POSOH) project seeks to develop strategies for preparing all learners--including typically underserved youth from non-mainstream cultures--to pursue bioenergy- and sustainability-related studies and careers, while exploring the contributions of traditional and scientific ways of knowing to our understanding of ecosystems and sustainability. The project serves the Northeastern WI bioregion, which includes three nearby Menominee, Oneida, and Stockbridge-Munsee reservations; the College of Menominee Nation, an accredited tribally controlled community college; and the surrounding community. It also encompasses cross-institutional partnerships spanning several large education and research institutions across Northeastern United States. We will provide an overview of the project and detail more specifically our experiences with the high school Sustainability Leadership Cohort model to discuss our learning process and the successes and gaps we have discovered along the way. The learning framework includes (a) collaborative curriculum design and development, (b) high school sustainability engagement activities, and (c) undergraduate internship opportunities. The High School Sustainability Leadership Cohort (SLC) is led by the College of Menominee Nation's Sustainable Development Institute in collaboration with its POSOH partners

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.

BE-PLUS: a new base editing tool with broadened editing window and enhanced fidelity.

PubMed

Jiang, Wen; Feng, Songjie; Huang, Shisheng; Yu, Wenxia; Li, Guanglei; Yang, Guang; Liu, Yajing; Zhang, Yu; Zhang, Lei; Hou, Yu; Chen, Jia; Chen, Jieping; Huang, Xingxu

2018-06-06

Base editor (BE), containing a cytidine deaminase and catalytically defective Cas9, has been widely used to perform base editing. However, the narrow editing window of BE limits its utility. Here, we developed a new editing technology named as base editor for programming larger C to U (T) scope (BE-PLUS) by fusing 10 copies of GCN4 peptide to nCas9(D10A) for recruiting scFv-APOBEC-UGI-GB1 to the target sites. The new system achieves base editing with a broadened window, resulting in an increased genome-targeting scope. Interestingly, the new system yielded much fewer unwanted indels and non-C-to-T conversions. We also demonstrated its potential use in gene disruption across the whole genome through induction of stop codons (iSTOP). Taken together, the BE-PLUS system offers a new editing tool with increased editing window and enhanced fidelity.

Kernel reconstruction methods for Doppler broadening - Temperature interpolation by linear combination of reference cross sections at optimally chosen temperatures

NASA Astrophysics Data System (ADS)

Ducru, Pablo; Josey, Colin; Dibert, Karia; Sobes, Vladimir; Forget, Benoit; Smith, Kord

2017-04-01

This article establishes a new family of methods to perform temperature interpolation of nuclear interactions cross sections, reaction rates, or cross sections times the energy. One of these quantities at temperature T is approximated as a linear combination of quantities at reference temperatures (Tj). The problem is formalized in a cross section independent fashion by considering the kernels of the different operators that convert cross section related quantities from a temperature T0 to a higher temperature T - namely the Doppler broadening operation. Doppler broadening interpolation of nuclear cross sections is thus here performed by reconstructing the kernel of the operation at a given temperature T by means of linear combination of kernels at reference temperatures (Tj). The choice of the L2 metric yields optimal linear interpolation coefficients in the form of the solutions of a linear algebraic system inversion. The optimization of the choice of reference temperatures (Tj) is then undertaken so as to best reconstruct, in the L∞ sense, the kernels over a given temperature range [Tmin ,Tmax ]. The performance of these kernel reconstruction methods is then assessed in light of previous temperature interpolation methods by testing them upon isotope 238U. Temperature-optimized free Doppler kernel reconstruction significantly outperforms all previous interpolation-based methods, achieving 0.1% relative error on temperature interpolation of 238U total cross section over the temperature range [ 300 K , 3000 K ] with only 9 reference temperatures.

Separation of Anisotropy and Exchange Broadening Using 15N CSA- 15N- 1H Dipole-Dipole Relaxation Cross-Correlation Experiments

NASA Astrophysics Data System (ADS)

Renner, Christian; Holak, Tad A.

2000-08-01

Based on the measurement of cross-correlation rates between 15N CSA and 15N-1H dipole-dipole relaxation we propose a procedure for separating exchange contributions to transverse relaxation rates (R2 = 1/T2) from effects caused by anisotropic rotational diffusion of the protein molecule. This approach determines the influence of anisotropy and chemical exchange processes independently and therefore circumvents difficulties associated with the currently standard use of T1/T2 ratios to determine the rotational diffusion tensor. We find from computer simulations that, in the presence of even small amounts of internal flexibility, fitting T1/T2 ratios tends to underestimate the anisotropy of overall tumbling. An additional problem exists when the N-H bond vector directions are not distributed homogeneously over the surface of a unit sphere, such as in helix bundles or β-sheets. Such a case was found in segment 4 of the gelation factor (ABP 120), an F-actin cross-linking protein, in which the diffusion tensor cannot be calculated from T1/T2 ratios. The 15N CSA tensor of the residues for this β-sheet protein was found to vary even within secondary structure elements. The use of a common value for the whole protein molecule therefore might be an oversimplification. Using our approach it is immediately apparent that no exchange broadening exists for segment 4 although strongly reduced T2 relaxation times for several residues could be mistaken as indications for exchange processes.

Broadening Participation in the Life Sciences with Social–Psychological Interventions

PubMed Central

Tibbetts, Yoi; Harackiewicz, Judith M.; Priniski, Stacy J.; Canning, Elizabeth A.

2016-01-01

Randomized controlled trials (RCTs) have recently documented the positive effects of social–psychological interventions on the performance and retention of underrepresented students in the life sciences. We review two types of social–psychological interventions that address either students’ well-being in college science courses or students’ engagement in science content. Interventions that have proven effective in RCTs in science courses (namely, utility-value [UV] and values-affirmation [VA] interventions) emphasize different types of student values—students’ perceptions of the value of curricular content and students’ personal values that shape their educational experiences. Both types of value can be leveraged to promote positive academic outcomes for underrepresented students. For example, recent work shows that brief writing interventions embedded in the curriculum can increase students’ perceptions of UV (the perceived importance or usefulness of a task for future goals) and dramatically improve the performance of first-generation (FG) underrepresented minority students in college biology. Other work has emphasized students’ personal values in brief essays written early in the semester. This VA intervention has been shown to close achievement gaps for women in physics classes and for FG students in college biology. By reviewing recent research, considering which interventions are most effective for different groups, and examining the causal mechanisms driving these positive effects, we hope to inform life sciences educators about the potential of social–psychological interventions for broadening participation in the life sciences. PMID:27543632

Aerospace Workforce Development: The Nebraska Proposal; and Native View Connections: A Multi-Consortium Workforce Development Proposal. UNO Aviation Monograph Series

NASA Technical Reports Server (NTRS)

Bowen, Brent D.; Russell, Valerie; Vlasek, Karisa; Avery, Shelly; Calamaio, Larry; Carstenson, Larry; Farritor, Shane; deSilva, Shan; Dugan, James; Farr, Lynne

2003-01-01

The NASA Nebraska Space Grant Consortium (NSGC) continues to recognize the necessity of increasing the quantity and quality of highly skilled graduates and faculty involved with NASA. Through NASA Workforce Development funds awarded in 2002, NSGC spearheaded customer- focused workforce training and higher education, industry and community partnerships that are significantly impacting the state s workforce in the science, technology, engineering, and mathematics (STEM) competencies. NSGC proposes to build upon these accomplishments to meet the steadily increasing demand for STEM skills and to safeguard minority representation in these disciplines. A wide range of workforce development activities target NASA s need to establish stronger connections among higher education, industry, and community organizations. Participation in the National Student Satellite Program (NSSP), Community Internship Program, and Nebraska Science and Technology Recruitment Fair will extend the pipeline of employees benefiting NASA as well as Nebraska. The diversity component of this proposal catapults from the exceptional reputation NSGC has built by delivering geospatial science experiences to Nebraska s Native Americans. For 6 years, NSGC has fostered and sustained partnerships with the 2 tribal colleges and 4 reservation school districts in Nebraska to foster aeronautics education and outreach. This program, the Nebraska Native American Outreach Program (NNAOP), has grown to incorporate more than educational institutions and is now a partnership among tribal community leaders, academia, tribal schools, and industry. The content focus has broadened from aeronautics in the school systems to aerospace technology and earth science applications in tribal community decision-making and workforce training on the reservations. To date, participants include faculty and staff at 4 Nebraska tribal schools, 2 tribal colleges, approximately 1,000 Native American youth, and over 1,200 community members

Multispectrum Analysis of 12CH4 in the v4 Band: I. Air-Broadened Half Widths, Pressure-Induced Shifts, Temperature Dependences and Line Mixing

NASA Technical Reports Server (NTRS)

Smith, MaryAnn H.; Benner, D. Chris; Predoi-Cross, Adriana; Venkataraman, Malathy Devi

2009-01-01

Lorentz air-broadened half widths, pressure-induced shifts and their temperature dependences have been measured for over 430 transitions (allowed and forbidden) in the v4 band of (CH4)-12 over the temperature range 210 to 314 K. A multispectrum non linear least squares fitting technique was used to simultaneously fit a large number of high-resolution (0.006 to 0.01/cm) absorption spectra of pure methane and mixtures of methane diluted with dry air. Line mixing was detected for pairs of A-, E-, and F-species transitions in the P- and R-branch manifolds and quantified using the off-diagonal relaxation matrix elements formalism. The measured parameters are compared to air- and N2-broadened values reported in the literature for the v4 and other bands. The dependence of the various spectral line parameters upon the tetrahedral symmetry species and rotational quantum numbers of the transitions is discussed. All data used in the present work were recorded using the McMath-Pierce Fourier transform spectrometer located at the National Solar Observatory on Kitt Peak.

Essential metrics for assessing sex & gender integration in health research proposals involving human participants.

PubMed

Day, Suzanne; Mason, Robin; Tannenbaum, Cara; Rochon, Paula A

2017-01-01

Integrating sex and gender in health research is essential to produce the best possible evidence to inform health care. Comprehensive integration of sex and gender requires considering these variables from the very beginning of the research process, starting at the proposal stage. To promote excellence in sex and gender integration, we have developed a set of metrics to assess the quality of sex and gender integration in research proposals. These metrics are designed to assist both researchers in developing proposals and reviewers in making funding decisions. We developed this tool through an iterative three-stage method involving 1) review of existing sex and gender integration resources and initial metrics design, 2) expert review and feedback via anonymous online survey (Likert scale and open-ended questions), and 3) analysis of feedback data and collective revision of the metrics. We received feedback on the initial metrics draft from 20 reviewers with expertise in conducting sex- and/or gender-based health research. The majority of reviewers responded positively to questions regarding the utility, clarity and completeness of the metrics, and all reviewers provided responses to open-ended questions about suggestions for improvements. Coding and analysis of responses identified three domains for improvement: clarifying terminology, refining content, and broadening applicability. Based on this analysis we revised the metrics into the Essential Metrics for Assessing Sex and Gender Integration in Health Research Proposals Involving Human Participants, which outlines criteria for excellence within each proposal component and provides illustrative examples to support implementation. By enhancing the quality of sex and gender integration in proposals, the metrics will help to foster comprehensive, meaningful integration of sex and gender throughout each stage of the research process, resulting in better quality evidence to inform health care for all.

Essential metrics for assessing sex & gender integration in health research proposals involving human participants

PubMed Central

Mason, Robin; Tannenbaum, Cara; Rochon, Paula A.

2017-01-01

Integrating sex and gender in health research is essential to produce the best possible evidence to inform health care. Comprehensive integration of sex and gender requires considering these variables from the very beginning of the research process, starting at the proposal stage. To promote excellence in sex and gender integration, we have developed a set of metrics to assess the quality of sex and gender integration in research proposals. These metrics are designed to assist both researchers in developing proposals and reviewers in making funding decisions. We developed this tool through an iterative three-stage method involving 1) review of existing sex and gender integration resources and initial metrics design, 2) expert review and feedback via anonymous online survey (Likert scale and open-ended questions), and 3) analysis of feedback data and collective revision of the metrics. We received feedback on the initial metrics draft from 20 reviewers with expertise in conducting sex- and/or gender-based health research. The majority of reviewers responded positively to questions regarding the utility, clarity and completeness of the metrics, and all reviewers provided responses to open-ended questions about suggestions for improvements. Coding and analysis of responses identified three domains for improvement: clarifying terminology, refining content, and broadening applicability. Based on this analysis we revised the metrics into the Essential Metrics for Assessing Sex and Gender Integration in Health Research Proposals Involving Human Participants, which outlines criteria for excellence within each proposal component and provides illustrative examples to support implementation. By enhancing the quality of sex and gender integration in proposals, the metrics will help to foster comprehensive, meaningful integration of sex and gender throughout each stage of the research process, resulting in better quality evidence to inform health care for all. PMID:28854192

Attenuating the alcohol allure: attentional broadening reduces rapid motivational response to alcohol pictures.

PubMed

Ryerson, Nicole C; Neal, Lauren B; Gable, Philip A

2017-04-01

Past research has found that exposure to alcohol cues causes a narrowing of attentional scope and enhances the neural responses associated with approach motivation. The current research sought to determine if a manipulated broadened (global) attentional scope would reduce approach-motivated neural reactivity to alcohol pictures. In the current study, participants (n = 82) were exposed to alcohol and neutral pictures following either a global or local attentional scope manipulation. Early motivated attentional processing was assessed using the N1 event-related potential (ERP), a neurophysiological marker of rapid motivated attention. A global attentional scope reduced N1 amplitudes to alcohol pictures as compared to a local attentional scope. Self-reported binge drinking related to larger N1 amplitudes to alcohol pictures, but not to neutral pictures. Individuals with greater binge drinking experience demonstrated increased rapid motivated attentional processing to alcohol pictures. These results suggest that enhancing a global (vs. local) attentional scope attenuates rapid motivated attentional processing of alcohol pictures in comparison to neutral pictures. Graphical abstract ᅟ.

Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Şahin, E; Hamid, R; Çelik, M

2014-11-30

We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level Λ-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected Λ-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have establishedmore » that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)« less

Broadening the definition of the genus Thalassaphorura Bagnall, 1949 (Collembola, Onychiuridae) with a new aberrant species from China

PubMed Central

Sun, Xin; Deharveng, Louis; Wu, Donghui

2013-01-01

Abstract A new species belonging to the tribe Thalassaphorurini, Thalassaphorura problematica sp. n., is described from Northeast China. The new species is closest to the large genus Thalassaphorura by its simple vesicles in PAO and its furcal rudiment, but it does not fit the definition of the genus by the absence of chaeta d0 on head, the number of chaetae in the distal whorl of tibiotarsi and the labium type. We discuss the relative weakness of these last characters at generic level, which lead us to assign the new species to Thalassaphorura instead of erecting a new genus. The diagnosis of Thalassaphorura is broadened accordingly. PMID:24453541

Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

PubMed

Svensson, Tomas; Lewander, Märta; Svanberg, Sune

2010-08-02

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In2O3 nanowires

NASA Astrophysics Data System (ADS)

Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P.; Schaller, Richard D.; Gosztola, David J.; Stroscio, Michael A.; Dutta, Mitra

2018-04-01

We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In2O3) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In2O3 nanostructure based device characteristics for potential optoelectronic applications. In2O3 nanowires with cubic crystal structure (c-In2O3) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor-liquid-solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy ({V}{{O}}) defects as confirmed using Raman spectroscopy. A combination of high resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of {V}{{O}} defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.

Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In 2 O 3 nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P.

We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In2O3) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In2O3 nanostructure based device characteristics for potential optoelectronic applications. In2O3 nanowires with cubic crystal structure (c-In2O3) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor–liquid–solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy (VO) defects as confirmed using Raman spectroscopy. A combination of highmore » resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of VO defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.« less

Kernel reconstruction methods for Doppler broadening — Temperature interpolation by linear combination of reference cross sections at optimally chosen temperatures

DOE PAGES

Ducru, Pablo; Josey, Colin; Dibert, Karia; ...

2017-01-25

This paper establishes a new family of methods to perform temperature interpolation of nuclear interactions cross sections, reaction rates, or cross sections times the energy. One of these quantities at temperature T is approximated as a linear combination of quantities at reference temperatures (T j). The problem is formalized in a cross section independent fashion by considering the kernels of the different operators that convert cross section related quantities from a temperature T 0 to a higher temperature T — namely the Doppler broadening operation. Doppler broadening interpolation of nuclear cross sections is thus here performed by reconstructing the kernelmore » of the operation at a given temperature T by means of linear combination of kernels at reference temperatures (T j). The choice of the L 2 metric yields optimal linear interpolation coefficients in the form of the solutions of a linear algebraic system inversion. The optimization of the choice of reference temperatures (T j) is then undertaken so as to best reconstruct, in the L∞ sense, the kernels over a given temperature range [T min,T max]. The performance of these kernel reconstruction methods is then assessed in light of previous temperature interpolation methods by testing them upon isotope 238U. Temperature-optimized free Doppler kernel reconstruction significantly outperforms all previous interpolation-based methods, achieving 0.1% relative error on temperature interpolation of 238U total cross section over the temperature range [300 K,3000 K] with only 9 reference temperatures.« less

Self-broadening of the sodium resonance lines and excitation transfer between the 3P32 and 3P12 levels

NASA Astrophysics Data System (ADS)

Huennekens, J.; Gallagher, A.

1983-04-01

Sodium vapor, in the density range 1013 to 5 × 1014 cm-3, was excited by a cw dye laser, tuned 20-150 GHz from either the D1 or D2 resonance line. We observed a three-peak scattered spectrum, consisting of the Rayleigh component at the laser frequency, and the two fluorescence components (direct and sensitized) at the atomic resonance-line frequencies. Corrections to the Rayleigh signals for anisotropy and polarization effects, and to the fluorescence signals for radiation trapping, were made in order to obtain the ratio of the sum of the total intensities of the two fluorescence components to that of the Rayleigh component. This ratio combined with a measurement of the line-wing absorption coefficient yields the sodium density and the D-line self-broadening rate coefficients [kbr=4.67×10-7 cm3s-1 (+/-15%) for the D2 line and kbr=3.07×10-7 cm3s-1 (+/-15%) for the D1 line]. Asymmetry in the self-broadened line wings due to fine-structure recoupling was observed. The measured intensity ratio of the D lines, combined with pulsed measurements of the effective radiative decay rates in the presence of radiation trapping, yields the fine-structure collisional-mixing cross section [σ(3P32-->3P12)=172Å2(+/-18%)] at T≅300° C. Our results are compared to other experiments and to theory.

Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In2O3 nanowires.

PubMed

Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P; Schaller, Richard D; Gosztola, David J; Stroscio, Michael A; Dutta, Mitra

2018-04-27

We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In 2 O 3 ) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In 2 O 3 nanostructure based device characteristics for potential optoelectronic applications. In 2 O 3 nanowires with cubic crystal structure (c-In 2 O 3 ) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor-liquid-solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy [Formula: see text] defects as confirmed using Raman spectroscopy. A combination of high resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of [Formula: see text] defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.

Radial distribution of the contributions to band broadening of a silica-based semi-preparative monolithic column.

PubMed

Abia, Jude A; Mriziq, Khaled S; Guiochon, Georges A

2009-04-01

Using an on-column local electrochemical microdetector operated in the amperometric mode, band elution profiles were recorded at different radial locations at the exit of a 10 mm id, 100 mm long silica-based monolithic column. HETP plots were then acquired at each of these locations, and all these results were fitted to the Knox equation. This provided a spatial distribution of the values of the eddy diffusion (A), the molecular diffusion (B), and the resistance to the kinetics of mass transfer (C) terms. Results obtained indicate that the wall region yields higher A values and smaller C values than the central core region. Significant radial fluctuations of these contributions to band broadening occur throughout the exit column cross-section. This phenomenon is due to the structural radial heterogeneity of the column.

Air-Broadening of H2O as a Function of Temperature: 696 - 2163 cm(exp -1)

NASA Technical Reports Server (NTRS)

Toth, R. A.; Brown, L. R.; Smith, M. A. H.; Devi, V. Malathy; Benner, D. Chris; Dulick, M.

2006-01-01

The temperature dependence of air-broadened halfwidths are reported for some 500 transitions in the (000)-(000) and (010)-(000) bands of H2(16)O using gas sample temperatures ranging from 241 to 388 K. These observations were obtained from infrared laboratory spectra recorded at 0.006 to 0.011 cm(exp-1) resolution with the McMath-Pierce Fourier transform spectrometer located at Kitt Peak. The experimental values of the temperature dependence exponents, eta, were grouped into eight subsets and fitted to empirical functions in a semi-global procedure. Overall, the values of eta were found to decrease with increasing rotational quantum number J. The number of measurements (over 2200) and transitions (586) involved exceeds by a large margin that of any other comparable reported study.

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.

Atom Resonance Lines for Modeling Atmosphere: Studies of Pressure-Broadening of Alkali Atom Resonance Lines for Modeling Atmospheres of Extrasolar Giant Planets and Brown Dwarfs

NASA Technical Reports Server (NTRS)

Hasan, Hashima (Technical Monitor); Kirby, K.; Babb, J.; Yoshino, K.

2005-01-01

We report on progress made in a joint program of theoretical and experimental research to study the line-broadening of alkali atom resonance lines due to collisions with species such as helium and molecular hydrogen. Accurate knowledge of the line profiles of Na and K as a function of temperature and pressure will allow such lines to serve as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar giant planets. A new experimental apparatus has been designed, built and tested over the past year, and we are poised to begin collecting data on the first system of interest, the potassium resonance lines perturbed by collisions with helium. On the theoretical front, calculations of line-broadening due to sodium collisions with helium are nearly complete, using accurate molecular potential energy curves and transition moments just recently computed for this system. In addition we have completed calculations of the three relevant potential energy curves and associated transition moments for K - He, using the MOLPRO quantum chemistry codes. Currently, calculations of the potential surfaces describing K-H2 are in progress.

Moving beyond the prostate: benefits in broadening the scope of research on men and cancer.

PubMed

Wenger, Lisa M; Oliffe, John L

2013-03-01

As researchers recognize the value in considering gender dynamics within the cancer experience, a majority of the masculinities work has centered on men with prostate cancer. This focus has positioned prostate cancer as the flagship of men's cancer (and perhaps men's health). There is value in this research. However, as 78% of men experience cancers of a different type, a narrow focus on prostate cancer does not necessarily account for broader intersections of cancer and masculinity. Argued here are the benefits to expanding the focus of research on men's cancer experiences. As researchers consider patterns and diversities among men managing an array of cancers, there is opportunity to broaden understanding of the challenges "cancer" can present for men, disrupt assumptions that the study of men's gendered experience of cancer must be tethered to male sex-specific biology, and enhance the relevance and impact of psychosocial interventions for men living with cancer.

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.

Intensity dependence narrowing of electromagnetically induced absorption in a Doppler-broadened medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dimitrijevic, J.; Arsenovic, D.; Jelenkovic, B. M.

In this paper, we present a theoretical model for studying the interaction between linearly polarized laser light and near-degenerated Zeeman sublevels for a multiple V-type atomic system of {sup 2}S{sub 1/2}F{sub g}=2{yields}{sup 2}P{sub 3/2}F{sub e}=3 transition in {sup 87}Rb. We have calculated the laser absorption in a Hanle configuration, as well as the amplitudes and the widths of electromagnetically induced absorption (EIA) in the range of laser intensities from 0.01 to 40 mW/cm{sup 2}. Our results, showing nonvanishing EIA amplitude, a nonmonotonic increase of the EIA width for the increase of laser intensity, and pronounced shape differences of the Hanlemore » EIA curves at different laser intensities, are in good agreement with recent experimental results. We have found that the EIA behaves differently than the electromagnetically induced transparency (EIT) as a function of the laser intensity. Both the amplitude and width of the EIA have narrow maximums at 1 to 2 mW/cm{sup 2}. We have shown the strong influence of Doppler broadening of atomic transition on Hanle resonances and have suggested the explanation of it.« less

H2-broadening, shifting and mixing coefficients of the doublets in the ν2 and ν4 bands of PH3 at room temperature

NASA Astrophysics Data System (ADS)

Salem, Jamel; Blanquet, Ghislain; Lepère, Muriel; Younes, Rached ben

2018-05-01

The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν2 and ν4 bands of PH3 perturbed by H2 have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH3), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν2 and ν4 bands of PH3 perturbed by hydrogen (H2) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A1 and A2 doublet lines with quantum numbers K = 3n, (n = 1, 2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.

The influence of coordinated defects on inhomogeneous broadening in cubic lattices

NASA Astrophysics Data System (ADS)

Matheson, P. L.; Sullivan, Francis P.; Evenson, William E.

2016-12-01

The joint probability distribution function (JPDF) of electric field gradient (EFG) tensor components in cubic materials is dominated by coordinated pairings of defects in shells near probe nuclei. The contributions from these inner shell combinations and their surrounding structures contain the essential physics that determine the PAC-relevant quantities derived from them. The JPDF can be used to predict the nature of inhomogeneous broadening (IHB) in perturbed angular correlation (PAC) experiments by modeling the G 2 spectrum and finding expectation values for V zz and η. The ease with which this can be done depends upon the representation of the JPDF. Expanding on an earlier work by Czjzek et al. (Hyperfine Interact. 14, 189-194, 1983), Evenson et al. (Hyperfine Interact. 237, 119, 2016) provide a set of coordinates constructed from the EFG tensor invariants they named W 1 and W 2. Using this parameterization, the JPDF in cubic structures was constructed using a point charge model in which a single trapped defect (TD) is the nearest neighbor to a probe nucleus. Individual defects on nearby lattice sites pair with the TD to provide a locus of points in the W 1- W 2 plane around which an amorphous-like distribution of probability density grows. Interestingly, however, marginal, separable PDFs appear adequate to model IHB relevant cases. We present cases from simulations in cubic materials illustrating the importance of these near-shell coordinations.

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...

Broadening of divertor heat flux profile with increasing number of ELM filaments in NSTX

DOE PAGES

Ahn, J. -W.; Maingi, R.; Canik, J. M.; ...

2014-11-13

Edge localized modes (ELMs) represent a challenge to future fusion devices, owing to cyclical high peak heat fluxes on divertor plasma facing surfaces. One ameliorating factor has been that the heat flux characteristic profile width has been observed to broaden with the size of the ELM, as compared with the inter-ELM heat flux profile. In contrast, the heat flux profile has been observed to narrow during ELMs under certain conditions in NSTX. Here we show that the ELM heat flux profile width increases with the number of filamentary striations observed, i.e., profile narrowing is observed with zero or very fewmore » striations. Because NSTX often lies on the long wavelength current-driven mode side of ideal MHD instabilities, few filamentary structures can be expected under many conditions. Lastly, ITER is also projected to lie on the current driven low-n stability boundary, and therefore detailed projections of the unstable modes expected in ITER and the heat flux driven in ensuing filamentary structures is needed.« less

76 FR 53882 - Proposed Information Collection; Comment Request; Trade Fair Certification Program Application

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-30

... agents or distributors; market research and exposure; and joint venture and licensing opportunities for...-sector firms. The TFC Program seeks to broaden the base of U.S. firms, particularly new-to-market...

The Fisk-Vanderbilt Masters-to-PhD Bridge Program: A Model for Broadening Participation of Underrepresented Groups in the Physical Sciences through Effective Partnerships with Minority-Serving Institutions

ERIC Educational Resources Information Center

Stassun, Keivan Guadalupe; Burger, Arnold; Lange, Sheila Edwards

2010-01-01

We describe the Fisk-Vanderbilt Masters-to-PhD Bridge program as a successful model for effective partnerships with minority-serving institutions toward significantly broadening the participation of underrepresented groups in the physical sciences. The program couples targeted recruitment with active retention strategies, and is built upon a…

Pressure broadening of the electric dipole and Raman lines of CO2 by argon: Stringent test of the classical impact theory at different temperatures on a benchmark system

NASA Astrophysics Data System (ADS)

Ivanov, Sergey V.; Buzykin, Oleg G.

2016-12-01

A classical approach is applied to calculate pressure broadening coefficients of CO2 vibration-rotational spectral lines perturbed by Ar. Three types of spectra are examined: electric dipole (infrared) absorption; isotropic and anisotropic Raman Q branches. Simple and explicit formulae of the classical impact theory are used along with exact 3D Hamilton equations for CO2-Ar molecular motion. The calculations utilize vibrationally independent most accurate ab initio potential energy surface (PES) of Hutson et al. expanded in Legendre polynomial series up to lmax = 24. New improved algorithm of classical rotational frequency selection is applied. The dependences of CO2 half-widths on rotational quantum number J up to J=100 are computed for the temperatures between 77 and 765 K and compared with available experimental data as well as with the results of fully quantum dynamical calculations performed on the same PES. To make the picture complete, the predictions of two independent variants of the semi-classical Robert-Bonamy formalism for dipole absorption lines are included. This method. however, has demonstrated poor accuracy almost for all temperatures. On the contrary, classical broadening coefficients are in excellent agreement both with measurements and with quantum results at all temperatures. The classical impact theory in its present variant is capable to produce quickly and accurately the pressure broadening coefficients of spectral lines of linear molecules for any J value (including high Js) using full-dimensional ab initio - based PES in the cases where other computational methods are either extremely time consuming (like the quantum close coupling method) or give erroneous results (like semi-classical methods).

High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility.

PubMed

Koch, J A; Stewart, R E; Beiersdorfer, P; Shepherd, R; Schneider, M B; Miles, A R; Scott, H A; Smalyuk, V A; Hsing, W W

2012-10-01

Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-α at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

On-the-fly Doppler broadening of unresolved resonance region cross sections

DOE PAGES

Walsh, Jonathan A.; Forget, Benoit; Smith, Kord S.; ...

2017-07-29

In this paper, two methods for computing temperature-dependent unresolved resonance region cross sections on-the-fly within continuous-energy Monte Carlo neutron transport simulations are presented. The first method calculates Doppler broadened cross sections directly from zero-temperature average resonance parameters. In a simulation, at each event that requires cross section values, a realization of unresolved resonance parameters is generated about the desired energy and temperature-dependent single-level Breit-Wigner resonance cross sections are computed directly via the analytical Ψ-x Doppler integrals. The second method relies on the generation of equiprobable cross section magnitude bands on an energy-temperature mesh. Within a simulation, the bands are sampledmore » and interpolated in energy and temperature to obtain cross section values on-the-fly. Both of the methods, as well as their underlying calculation procedures, are verified numerically in extensive code-to-code comparisons. Energy-dependent pointwise cross sections calculated with the newly-implemented procedures are shown to be in excellent agreement with those calculated by a widely-used nuclear data processing code. Relative differences at or below 0.1% are observed. Integral criticality benchmark results computed with the proposed methods are shown to reproduce those computed with a state-of-the-art processed nuclear data library very well. In simulations of fast spectrum systems which are highly-sensitive to the representation of cross section data in the unresolved region, k-eigenvalue and neutron flux spectra differences of <10 pcm and <1.0% are observed, respectively. The direct method is demonstrated to be well-suited to the calculation of reference solutions — against which results obtained with a discretized representation may be assessed — as a result of its treatment of the energy, temperature, and cross section magnitude variables as continuous. Also, because there is no pre

Broadening Participation in the Life Sciences with Social-Psychological Interventions.

PubMed

Tibbetts, Yoi; Harackiewicz, Judith M; Priniski, Stacy J; Canning, Elizabeth A

Randomized controlled trials (RCTs) have recently documented the positive effects of social-psychological interventions on the performance and retention of underrepresented students in the life sciences. We review two types of social-psychological interventions that address either students' well-being in college science courses or students' engagement in science content. Interventions that have proven effective in RCTs in science courses (namely, utility-value [UV] and values-affirmation [VA] interventions) emphasize different types of student values-students' perceptions of the value of curricular content and students' personal values that shape their educational experiences. Both types of value can be leveraged to promote positive academic outcomes for underrepresented students. For example, recent work shows that brief writing interventions embedded in the curriculum can increase students' perceptions of UV (the perceived importance or usefulness of a task for future goals) and dramatically improve the performance of first-generation (FG) underrepresented minority students in college biology. Other work has emphasized students' personal values in brief essays written early in the semester. This VA intervention has been shown to close achievement gaps for women in physics classes and for FG students in college biology. By reviewing recent research, considering which interventions are most effective for different groups, and examining the causal mechanisms driving these positive effects, we hope to inform life sciences educators about the potential of social-psychological interventions for broadening participation in the life sciences. © 2016 Y. Tibbetts 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

Stark broadening of several Bi IV spectral lines of astrophysical interest

NASA Astrophysics Data System (ADS)

Colón, C.; Moreno-Díaz, C.; de Andrés-García, I.; Alonso-Medina, A.

2017-09-01

The presence of spectral lines of bismuth in stellar atmospheres has been reported in different stars. The anomalous values of the spectral intensities of Bi II and Bi III, compared to the theoretical Local Termodinamic Equilibrium (LTE) standards of Bi I/Bi II/Bi III, have been reported in the spectra obtained with the High Resolution Spectrograph of the Hubble/Goddard Space Telescope in the chemically peculiar stars HgMn stars χ Lupi and HR 7775. Spectral lines of 1436.8, 1902.3, 2630.9 and 2936.7 Å of Bi II and 1423.4 Å of Bi III were reported and their relative intensities were measured in these studies Litzén & Wahlgren 2002. These lines are overlapped with spectral lines of 1437.65, 2630.1 and 2937.1 Å of Bi IV. A study of the Stark broadening parameters of Bi IV spectral lines can help to study these overlaps. In this paper, using the Griem semi-empirical approach, we report calculated values of the Stark parameters for 64 spectral lines of Bi IV. The matrix elements used in these calculations have been determined from 17 configurations of Bi IV. They were calculated using the cowan code including core polarization effects. Data are displayed for an electron density of 1017 cm-3 and temperatures T = 10 000-160 000 K. Also calculated radiative lifetimes for 12 levels with experimental lifetime are presented, in order to test the goodness of our calculations. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed.

Phonon characteristics of high {Tc} superconductors from neutron Doppler broadening measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trela, W.J.; Kwei, G.H.; Lynn, J.E.

Statistical information on the phonon frequency spectrum of materials can be measured by neutron transmission techniques if they contain nuclei with low energy resonances, narrow enough to be Doppler-broadened, in their neutron cross sections. The authors have carried out some measurements using this technique for materials of the lanthanum barium cuprate class, La{sub 2{minus}x}Ba{sub x}CuO{sub 4}. Two samples with slightly different concentrations of oxygen, one being superconductive, the other not, were examined. Pure lanthanum cuprate was also measured. Lanthanum, barium and copper all have relatively low energy narrow resonances. Thus it should be possible to detect differences in the phononsmore » carried by different kinds of atom in the lattice. Neutron cross section measurements have been made with high energy resolution and statistical precision on the 59m flight path of LANSCE, the pulsed spallation neutron source at Los Alamos National Laboratory. Measurements on all three materials were made over a range of temperatures from 15K to 300K, with small steps through the critical temperature region near 27K. No significant changes in the mean phonon energy of the lanthanum atoms were observed near the critical temperature of the super-conducting material. It appears however that the mean phonon energy of lanthanum in the superconductor is considerably higher than that in the non-superconductors. The samples used in this series of experiments were too thin in barium and copper to determine anything significant about their phonon spectra.« less

Broadening of Generalized Anxiety Disorders Definition Does not Affect the Response to Psychiatric Care: Findings from the Observational ADAN Study

PubMed Central

Álvarez, Enrique; Carrasco, Jose L; Olivares, José M; López-Gómez, Vanessa; Vilardaga, Inma; Perez, María

2012-01-01

Objective: To elucidate the consequences of broadening DSM-IV criteria for generalized anxiety disorder (GAD), we examined prospectively the evolution of GAD symptoms in two groups of patients; one group diagnosed according to DSM-IV criteria and the other, according to broader criteria. Method: Multicentre, prospective and observational study conducted on outpatient psychiatric clinics. Patients were selected from October 2007 to January 2009 and diagnosed with GAD according to DSM-IV criteria (DSM-IV group) or broader criteria. Broader criteria were considered 1-month of excessive or non-excessive worry and only 2 of the associated symptoms listed on DSM-IV for GAD diagnosis. Socio-demographic data, medical history and functional outcome measures were collected three times during a 6-month period. Results: 3,549 patients were systematically recruited; 1,815 patients in DSM-IV group (DG) and 1,264 in broad group (BG); 453 patients did not fulfil inclusion criteria and were excluded. Most patients (87.9% in DG, 82.0% in BG) were currently following pharmacological therapies (mainly benzodiazepines) to manage their anxiety symptoms. The changes observed during the study were: 49.0% and 58.0%, respectively of patients without anxiety symptoms as per HAM-A scale at the 6 month visit (p=0.261) and 59.7% and 67.7%, respectively (p=0.103) of responder rates (> 50% reduction of baseline scoring). Conclusion: Broadening of GAD criteria does not seem to affect psychiatric care results in subjects with GAD, is able to identify the core symptoms of the disease according to the DSM-IV criteria and could lead to an earlier diagnosis. PMID:23173012

Temporal reflection as a spectral-broadening mechanism in dual-pumped dispersion-decreasing fibers and its connection to dispersive waves

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

0.Measurements of H216O Linestrengths and Air-Induced Broadenings and Shifts in the 815-nm Spectral Region

NASA Technical Reports Server (NTRS)

Ponsardin, Patrick L.; Browell, Edward V.

1997-01-01

The linestrengths for 40 absorption lines of H2 16-O water vapor that were located between 813 and 820 nm were measured; most of these lines were selected for their potential usefulness in laser remote measurements of atmospheric humidity using the differential absorption lidar technique. The air-induced pressure-broadening coefficients were also measured for 32 of these lines and the air-induced pressure shift coefficients were measured for 29 lines. These spectroscopic parameters were derived from spectra obtained with an AlGaAs diode laser and two long-path absorption cells. Collisional narrowing effects were observed and were accurately described by a Galatry profile. Comparisons were made with previous experimental work or theoretical calculations as available.

Polarizability and the optical theorem for a two-level atom with radiative broadening

NASA Astrophysics Data System (ADS)

Berman, Paul R.; Boyd, Robert W.; Milonni, Peter W.

2006-11-01

The effect of spontaneous decay on the linear polarizability of an atom is typically included by adding imaginary parts to the frequency denominators that appear in the Kramers-Heisenberg formula. It has been shown for a two-level atom with radiative broadening that these (frequency-dependent) imaginary parts must be included in both the resonant and antiresonant frequency denominators [P. W. Milonni and R. W. Boyd, Phys. Rev. A 69, 023814 (2004)]; however, the expression obtained by Milonni and Boyd for the polarizability does not satisfy the optical theorem, if contributions from non-rotating-wave terms are included. In this paper, we derive a more accurate expression for the polarizability. The calculations are rather complicated and require that we go beyond the standard Weisskopf-Wigner approximation. We present calculations carried out in both the Heisenberg and Schrödinger pictures, since they offer complementary methods for understanding the dynamics of the Rayleigh scattering associated with the atomic polarizability. Moreover, it is shown that the shifts associated with the excited state are not the Lamb shifts of an isolated atom, but depend on the dynamics of the atom-field interaction. Our results for the polarizability are consistent with those obtained recently by Loudon and Barnett using a Green’s-function approach.

A temporally and spatially resolved electron density diagnostic method for the edge plasma based on Stark broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zafar, A., E-mail: zafara@ornl.gov; Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830; Martin, E. H.

2016-11-15

An electron density diagnostic (≥10{sup 10} cm{sup −3}) 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 the n = 6–2 hydrogen Balmer series transition. The profile is then fit to a fully quantum mechanical model including the appropriate electric and magnetic field operators. The quasi-static approach used to calculate the Doppler-free spectral line profile is outlined here and the results from the model are presented for H-δ spectra for electron densities of 10{sup 10}–10{sup 13} cm{supmore » −3}. The profile shows complex behavior due to the interaction between the magnetic substates of the atom.« less

Linking the thermodynamic temperature to an optical frequency: recent advances in Doppler broadening thermometry

PubMed Central

2016-01-01

Laser spectroscopy in the linear regime of radiation–matter interaction is a powerful tool for measuring thermodynamic quantities in a gas at thermodynamic equilibrium. In particular, the Doppler effect can be considered a gift of nature, linking the thermal energy to an optical frequency, namely the line centre frequency of an atomic or molecular spectral line. This is the basis of a relatively new method of primary gas thermometry, known as Doppler broadening thermometry (DBT). This paper reports on the efforts that have been carried out, in the last decade, worldwide, to the end of making DBT competitive with more consolidated and accurate methodologies, such as acoustic gas thermometry and dielectric constant gas thermometry. The main requirements for low-uncertainty DBT, of both theoretical and technical nature, will be discussed, with a special focus on those related to the line shape model and to the frequency scale. A deep comparison among the different molecules that have been selected in successful DBT implementations is also reported. Finally, for the first time, to the best of my knowledge, the influence of refractive index effects is discussed. PMID:26903093

Perceived workplace harassment experiences and problem drinking among physicians: broadening the stress/alienation paradigm.

PubMed

Richman, J A; Flaherty, J A; Rospenda, K M

1996-03-01

Sociologists who embrace the stress or alienation paradigms generally focus on explaining problem drinking in low status occupations. By contrast, this paper argues that a broadened conceptualization of stress and alienation which incorporates abusive work relationships has utility for explaining male and female drinking outcomes in both high and low status occupations. We provide empirical data on the relationship between perceived abusive experiences and drinking outcomes in a cohort of male and female physicians in their internship year of training. The data show that perceived sexual harassment, discriminatory treatment and psychological humiliation relate to various drinking outcomes in men and women, controlling for drinking prior to the internship year. While females were more likely to report experiencing abuse, these perceived experiences had deleterious effects on drinking outcomes for both genders. Personal vulnerability (narcissism) brought into the training environment somewhat influenced the later reporting of abusive experiences by males but not by females. Regression analyses showed that, for both males and females, work-place abusive experiences in interaction with personality vulnerability best explained drinking outcomes. The implications of these results for the design of future alcohol-related work-place studies are discussed.

Collision induced broadening and shifting of the H and K lines of Ca+ at low temperature

NASA Astrophysics Data System (ADS)

Wang, Xin; Zhang, Rui; Shen, Yong; Liu, Qu; Zou, Hongxin; Yan, Bing

2017-09-01

Multireference configuration interaction method was used to compute the potential energy curves of Λ-S states correlating with lowest three atomic limits in Ca+-He molecular collision system. The potential energy curves of nine Ω states were obtained with inclusion of spin-orbit coupling. And the electric dipole and quadrupole moment matrix elements between excited states and ground state were also computed. Furthermore, with aid of the Anderson-Talman theory we calculated the broadening and shifting coefficients for Ca+-He spectral lines in the low temperature regime. For H line, α = 0.303 × 10-20 cm-1/cm-3, β = -0.0527 × 10-20cm-1/cm-3; For K line, α = 0.233 × 10-20cm-1/cm-3, β = -0.0402 × 10-20cm-1/cm-3 These results are helpful to understand the collision effects induced by He atom in further spectra investigations of cold Ca+ ions.

Application of Positron Doppler Broadening Spectroscopy to the Measurement of the Uniformity of Composite Materials

NASA Astrophysics Data System (ADS)

Quarles, C. A.; Sheffield, Thomas; Stacy, Scott; Yang, Chun

2009-03-01

The uniformity of rubber-carbon black composite materials has been investigated with positron Doppler Broadening Spectroscopy (DBS). The number of grams of carbon black (CB) mixed into one hundred grams of rubber, phr, is used to characterize a sample. A typical concentration for rubber in tires is 50 phr. The S parameter measured by DBS has been found to depend on the phr of the sample as well as the type of rubber and carbon black. The variation in carbon black concentration within a surface area of about 5 mm diameter can be measured by moving a standard Na-22 or Ge-68 positron source over an extended sample. The precision of the concentration measurement depends on the dwell time at a point on the sample. The time required to determine uniformity over an extended sample can be reduced by running with much higher counting rate than is typical in DBS and correcting for the systematic variation of S parameter with counting rate. Variation in CB concentration with mixing time at the level of about 0.5% has been observed.

A carbon-13 and proton nuclear magnetic resonance study of some experimental referee broadened-specification /ERBS/ turbine fuels

NASA Technical Reports Server (NTRS)

Dalling, D. K.; Pugmire, R. J.

1982-01-01

Preliminary results of a nuclear magnetic resonance (NMR) spectroscopy study of alternative jet fuels are presented. A referee broadened-specification (ERBS) aviation turbine fuel, a mixture of 65 percent traditional kerosene with 35 percent hydrotreated catalytic gas oil (HCGO) containing 12.8 percent hydrogen, and fuels of lower hydrogen content created by blending the latter with a mixture of HCGO and xylene bottoms were studied. The various samples were examined by carbon-13 and proton NMR at high field strength, and the resulting spectra are shown. In the proton spectrum of the 12.8 percent hydrogen fuel, no prominent single species is seen while for the blending stock, many individual lines are apparent. The ERBS fuels were fractionated by high-performance liquid chromatography and the resulting fractions analyzed by NMR. The species found are identified.

Spectral and far-field broadening due to stimulated rotational Raman scattering driven by the Nike krypton fluoride laser.

PubMed

Weaver, James; Lehmberg, Robert; Obenschain, Stephen; Kehne, David; Wolford, Matthew

2017-11-01

Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248  nm) has been observed at the Nike laser over extended propagation paths in air during high power operation. Although this phenomenon is not significant for standard operating configurations at Nike, broadening of the laser spectrum and far-field focal profiles has been observed once the intensity-path length product exceeds a threshold of approximately 1  TW/cm. This paper presents experimental results and a new theoretical evaluation of these effects. The observations suggest that significantly broader spectra can be achieved with modest degradation of the final focal distribution. These results point to a possible path for enhanced laser-target coupling with the reduction of laser-plasma instabilities due to broad laser bandwidth produced by the SRRS.

The protective role of compassion satisfaction for therapists who work with sexual violence survivors: an application of the broaden-and-build theory of positive emotions.

PubMed

Samios, Christina; Abel, Lisa M; Rodzik, Amber K

2013-01-01

Therapists who work with trauma survivors, such as survivors of sexual violence, can experience compassion satisfaction while experiencing negative effects of trauma work, such as secondary traumatic stress. We examined whether the negative effects of secondary traumatic stress on therapist adjustment would be buffered by compassion satisfaction and whether the broaden-and-build theory of positive emotions could be applied to examine the factors (positive emotions and positive reframing) that relate to compassion satisfaction. Sixty-one therapists who work with sexual violence survivors completed measures of secondary traumatic stress, compassion satisfaction, adjustment, positive emotions and positive reframing. Hierarchical multiple regression analyses found that compassion satisfaction buffered the negative impact of secondary traumatic stress on therapist adjustment when adjustment was conceptualised as anxiety. Using non-parametric bootstrapping, we found that the relationship between greater positive emotions and greater compassion satisfaction was partially mediated by positive reframing. The findings indicate that compassion satisfaction is likely to be helpful in ameliorating the negative effects of secondary traumatic stress on anxiety in therapists who work with sexual violence survivors and that the broaden-and-build theory of positive emotions may provide a strong theoretical basis for the further examination of compassion satisfaction in trauma therapists.

Theory of anisotropic hybridization-broadened magnetic response in cerium and actinide systems

NASA Astrophysics Data System (ADS)

Hu, Gong-Jia; Cooper, Bernard R.

1993-11-01

Inelastic-neutron-scattering measurements on cerium and plutonium monopnictides, thought to have moderately delocalized f electrons, yield magnetic-excitation spectra with anisotropic dispersion; while reasonably sharp excitations have been observed only for USb and UTe among presumably more-delocalized uranium monopnictides and monochalcogenides. For UTe the broadening as well as the dispersion is quite anisotropic. We have now extended our previous theory for the magnetic behavior of hybridizing partially delocalized f-electron systems to include hybridization-induced relaxation effects in the magnetic response, and this work and results are reported in the present paper. Each partially delocalized f-electron ion is coupled by hybridization to the band sea; and this both leads to a hybridization-mediated anisotropic two-ion interaction giving magnetic ordering and also gives a damping mechanism, via the coupling to the band sea, for the excitations of the magnetically ordered lattice. This coupling also provides a strong renormalization of the magnetic-excitation energies obtained for the ionic lattice coupled by the two-ion interaction. To treat these effects on the magnetic response we have developed a formalism for calculating the dynamic susceptibility based on the projection-operator method developed by Mori and others. We have applied our model and theory to the behavior of CeSb, CeBi, PuSb, UP, UAs, and UTe; and excellent overall agreement with the wide range of unusual experimentally observed anisotropic magnetic-excitation behavior is obtained.

Analysis of Postdoctoral Training Outcomes That Broaden Participation in Science Careers.

PubMed

Rybarczyk, Brian J; Lerea, Leslie; Whittington, Dawayne; Dykstra, Linda

2016-01-01

Postdoctoral training is an optimal time to expand research skills, develop independence, and shape career trajectories, making this training period important to study in the context of career development. Seeding Postdoctoral Innovators in Research and Education (SPIRE) is a training program that balances research, teaching, and professional development. This study examines the factors that promote the transition of postdocs into academic careers and increase diversity in science, technology, engineering, and mathematics. Data indicate that SPIRE scholars (n = 77) transition into faculty positions at three times the national average with a greater proportion of underrepresented racial minorities (URMs) and females represented among SPIRE scholars. Logistic regression models indicate that significant predictors are the intended career track at the start of the postdoctoral training and the number of publications. Factors necessary for successful transition are teaching experience as independent instructors, professional development opportunities, and the experience of balancing teaching with research. Scholars' continued commitment to increasing diversity in their faculty roles was demonstrated by their attainment of tenure-track positions at minority-serving institutions, continued mentorship of URMs, and engagement with diversity initiatives. These results suggest that a postdoctoral program structured to include research, teaching, and diversity inclusion facilitates attainment of desired academic positions with sustained impacts on broadening participation. © 2016 B. J. Rybarczyk 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).

Determinants of hospital nurse intention to remain employed: broadening our understanding

PubMed Central

Tourangeau, Ann E; Cummings, Greta; Cranley, Lisa A; Ferron, Era Mae; Harvey, Sarah

2010-01-01

Title Determinants of hospital nurse intention to remain employed: broadening ourunderstanding. Aim This paper is a report of a study to identify nurse reported determinants of intention to remain employed and to develop a model explaining determinants of hospital nurse intention to remain employed. Background A worsening shortage of nurses globally suggests that efforts must be made to promote retention of nurses. However, effective retention promotion strategies depend on understanding the factors influencing nurse retention. Methods A descriptive study using focus group methodology was implemented. Thirteen focus groups including 78 nurses were carried out in two Canadian provinces in 2007. Thematic analysis strategies were incorporated to analyse the data. Findings Eight thematic categories reflecting factors nurses described as influencing their intentions to remain employed emerged from focus groups: (1) relationships with co-workers, (2) condition of the work environment, (3) relationship with and support from one’s manager, (4) work rewards, (5) organizational support and practices, (6) physical and psychological responses to work, (7) patient relationships and other job content, and (8) external factors. A model of determinants of hospital nurse intention to remain employed is hypothesized. Conclusion Findings were both similar to and different from previous research. The overriding concept of job satisfaction was not found. Rather, nurse assessments of satisfaction within eight thematic categories were found to influence intentions to remain employed. Further testing of the hypothesized model is required to determine its global utility. Understanding determinants of intention to remain employed can lead to development of strategies that strengthen nurse retention. Incorporation of this knowledge in nurse education programmes is essential. PMID:20423434

Target-in-the-loop phasing of a fiber laser array fed by a linewidth-broadened master oscillator

NASA Astrophysics Data System (ADS)

Hyde, Milo W.; Tyler, Glenn A.; Rosado Garcia, Carlos

2017-05-01

In a recent paper [J. Opt. Soc. Am. A 33, 1931-1937 (2016)], the target-in-the-loop (TIL) phasing of an RF-modulated or multi-phase-dithered fiber laser array, fed by a linewidth-broadened master oscillator (MO) source, was investigated. It was found that TIL phasing was possible even on a target with scattering features separated by more than the MO's coherence length as long as the received, backscattered irradiance changed with the array's modulation or phase dither. To simplify the problem and gain insight into how temporal coherence affects TIL phasing, speckle and atmospheric turbulence were omitted from the analysis. Here, the scenario analyzed in the prior work is generalized by including speckle and turbulence. First, the key analytical result from the prior paper is reviewed. Simulations, including speckle and turbulence, are then performed to test whether the conclusions derived from that result hold under more realistic conditions.

A comparison of the doppler-broadened positron annihilation spectra of neutron irradiated Al 2O 3 and MgAl 2O 3

NASA Astrophysics Data System (ADS)

Jones, P. L.; Schaffer, J. P.; Cocks, F. H.; Clinard, F. W.; Hurley, G. F.

1985-01-01

Radiation damage studies of oxides and ceramics have become of increasing importance due to the projected use of these materials in thermonuclear fusion reactors as electronic insulators and first wall materials. In addition these materials are important in RAD waste disposal. As part of a study of the defect structure in radiation damaged ceramics Doppler-broadened positron annihilation spectra have been obtained for a series of single crystal sapphire (α-Al 2O 3) and polycrystal (1:1) and (1:2) magnesium aluminate spinel (MgO·Al 2O 3 and MgO-2Al 2O 3) samples. These samples were irradiated in EBR-II to a fluence of 3 × 10 25 n/m 2 (E > 0.1 MeV) at 740°C, and 2 × 10 26 n/m 2 (E > 0.1 MeV) at ~ 550°C respectively. Positron annihilation spectra lineshapes for the irradiated, annealed, and as-received samples of both materials were compared using S parameter analysis. These calculations were made on deconvoluted gamma ray spectra that were free of any instrumental broadening effects. In this way, absolute S parameter changes could be calculated. The observed changes in the S parameter are consistent with independent volume swelling measurements for both the α-A1 2O 3 and the (1:2) MgAl 2O 4 samples. However, the change in S parameter measured for the (1:1) spinel is contrary to the measured volume change. This apparent anomaly indicates a predominence of interstitial as opposed to vacancy type defects in this material.

Proposed modification to the specification for dry heat microbial reduction of spacecraft hardware for future US missions

NASA Astrophysics Data System (ADS)

James; Spry, A.; Beaudet, Robert; Schubert, Wayne

Dry heat microbial reduction (DHMR) is the primary technique used to reduce the microbial load of spacecraft and component parts to comply with planetary protection requirements. Often, manufacturing processes involve heating flight hardware to high temperatures for purposes other than planetary protection DHMR. At present, the existing specification in NASA document NPR8020.12C, describing the process lethality on B. atrophaeus (ATCC 9372) bacterial spores, does not allow for additional planetary protection bioburden reduction credit for processing outside a narrow temperature, time and humidity window. However, recent studies (Schubert et al., COSPAR 2008) from a comprehensive multi-year laboratory research effort have generated enhanced data sets on four aspects of the current specification: time and temperature combination effects, the effect that humidity has on spore lethality, the lethality for spores with exceptionally high thermal resistance (so called "hardies"), and the extended exposure requirement for encapsulated microorganisms. This paper describes proposed modifications to the specification, based on the data set generated in the referenced study. The proposed modifications are intended to broaden the scope of the current specification while still maintaining a confident conservative interpretation of the lethality of the DHMR process on microorganisms. Potential cost and schedule benefits to future missions utilizing the revised specification will be highlighted.

Approximate transient and long time limit solutions for the band broadening induced by the thin sidewall-layer in liquid chromatography columns.

PubMed

Broeckhoven, Ken; Desmet, Gert

2007-11-16

Using a combination of both analytical and numerical techniques, approximate analytical expressions have been established for the transient and long time limit band broadening, originating from the presence of a thin disturbed sidewall layer in liquid chromatography columns, including packed, monolithic as well as microfabricated columns. The established expressions can be used to compare the importance of a thin disturbed sidewall layer with that of other radial heterogeneity effects (such as transcolumn packing density variations due to the relief of packing stresses). The expressions are independent of the actual velocity profile inside the layer as long as the disturbed sidewall layer occupies less than 2.5% of the column width.

H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2

NASA Astrophysics Data System (ADS)

Wilzewski, Jonas S.; Gordon, Iouli E.; Kochanov, Roman V.; Hill, Christian; Rothman, Laurence S.

2016-01-01

To increase the potential for use of the HITRAN database in astronomy, experimental and theoretical line-broadening coefficients, line shifts and temperature-dependence exponents of molecules of planetary interest broadened by H2, He, and CO2 have been assembled from available peer-reviewed sources. The collected data were used to create semi-empirical models so that every HITRAN line of the studied molecules has corresponding parameters. Since H2 and He are major constituents in the atmospheres of gas giants, and CO2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for remote sensing studies of planetary atmospheres. In this paper we make the first step in assembling complete sets of these parameters, thereby creating datasets for SO2, NH3, HF, HCl, OCS and C2H2.

Using refractive optics to broaden the focus of an X-ray mirror

PubMed Central

Dhamgaye, Vishal

2017-01-01

X-ray mirrors are widely used at synchrotron radiation sources for focusing X-rays into focal spots of size less than 1 µm. The ability of the beamline optics to change the size of this spot over a range up to tens of micrometres can be an advantage for many experiments such as X-ray microprobe and X-ray diffraction from micrometre-scale crystals. It is a requirement that the beam size change should be reproducible and it is often essential that the change should be rapid, for example taking less than 1 s, in order to allow high data collection rates at modern X-ray sources. In order to provide a controlled broadening of the focused spot of an X-ray mirror, a series of refractive optical elements have been fabricated and installed immediately before the mirror. By translation, a new refractive element is moved into the X-ray beam allowing a variation in the size of the focal spot in the focusing direction. Measurements using a set of prefabricated refractive structures with a test mirror showed that the focused beam size could be varied from less than 1 µm to over 10 µm for X-rays in the energy range 10–20 keV. As the optics is in-line with the X-ray beam, there is no effect on the centroid position of the focus. Accurate positioning of the refractive optics ensures reproducibility in the focused beam profile and no additional re-alignment of the optics is required. PMID:28664880

Using refractive optics to broaden the focus of an X-ray mirror.

PubMed

Laundy, David; Sawhney, Kawal; Dhamgaye, Vishal

2017-07-01

X-ray mirrors are widely used at synchrotron radiation sources for focusing X-rays into focal spots of size less than 1 µm. The ability of the beamline optics to change the size of this spot over a range up to tens of micrometres can be an advantage for many experiments such as X-ray microprobe and X-ray diffraction from micrometre-scale crystals. It is a requirement that the beam size change should be reproducible and it is often essential that the change should be rapid, for example taking less than 1 s, in order to allow high data collection rates at modern X-ray sources. In order to provide a controlled broadening of the focused spot of an X-ray mirror, a series of refractive optical elements have been fabricated and installed immediately before the mirror. By translation, a new refractive element is moved into the X-ray beam allowing a variation in the size of the focal spot in the focusing direction. Measurements using a set of prefabricated refractive structures with a test mirror showed that the focused beam size could be varied from less than 1 µm to over 10 µm for X-rays in the energy range 10-20 keV. As the optics is in-line with the X-ray beam, there is no effect on the centroid position of the focus. Accurate positioning of the refractive optics ensures reproducibility in the focused beam profile and no additional re-alignment of the optics is required.

Charge Carrier Hopping Dynamics in Homogeneously Broadened PbS Quantum Dot Solids.

PubMed

Gilmore, Rachel H; Lee, Elizabeth M Y; Weidman, Mark C; Willard, Adam P; Tisdale, William A

2017-02-08

Energetic disorder in quantum dot solids adversely impacts charge carrier transport in quantum dot solar cells and electronic devices. Here, we use ultrafast transient absorption spectroscopy to show that homogeneously broadened PbS quantum dot arrays (σ hom 2 :σ inh 2 > 19:1, σ inh /k B T < 0.4) can be realized if quantum dot batches are sufficiently monodisperse (δ ≲ 3.3%). The homogeneous line width is found to be an inverse function of quantum dot size, monotonically increasing from ∼25 meV for the largest quantum dots (5.8 nm diameter/0.92 eV energy) to ∼55 meV for the smallest (4.1 nm/1.3 eV energy). Furthermore, we show that intrinsic charge carrier hopping rates are faster for smaller quantum dots. This finding is the opposite of the mobility trend commonly observed in device measurements but is consistent with theoretical predictions. Fitting our data to a kinetic Monte Carlo model, we extract charge carrier hopping times ranging from 80 ps for the smallest quantum dots to over 1 ns for the largest, with the same ethanethiol ligand treatment. Additionally, we make the surprising observation that, in slightly polydisperse (δ ≲ 4%) quantum dot solids, structural disorder has a greater impact than energetic disorder in inhibiting charge carrier transport. These findings emphasize how small improvements in batch size dispersity can have a dramatic impact on intrinsic charge carrier hopping behavior and will stimulate further improvements in quantum dot device performance.

Building 1D resonance broadened quasilinear (RBQ) code for fast ions Alfvénic relaxations

NASA Astrophysics Data System (ADS)

Gorelenkov, Nikolai; Duarte, Vinicius; Berk, Herbert

2016-10-01

The performance of the burning plasma is limited by the confinement of superalfvenic fusion products, e.g. alpha particles, which are capable of resonating with the Alfvénic eigenmodes (AEs). The effect of AEs on fast ions is evaluated using a resonance line broadened diffusion coefficient. The interaction of fast ions and AEs is captured for cases where there are either isolated or overlapping modes. A new code RBQ1D is being built which constructs diffusion coefficients based on realistic eigenfunctions that are determined by the ideal MHD code NOVA. The wave particle interaction can be reduced to one-dimensional dynamics where for the Alfvénic modes typically the particle kinetic energy is nearly constant. Hence to a good approximation the Quasi-Linear (QL) diffusion equation only contains derivatives in the angular momentum. The diffusion equation is then one dimensional that is efficiently solved simultaneously for all particles with the equation for the evolution of the wave angular momentum. The evolution of fast ion constants of motion is governed by the QL diffusion equations which are adapted to find the ion distribution function.

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

NASA Astrophysics Data System (ADS)

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

2012-08-01

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

Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical description

NASA Astrophysics Data System (ADS)

Ma, Weiguang; Silander, Isak; Hausmaninger, Thomas; Axner, Ove

2016-01-01

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is conventionally described by an expression (here referred to as the CONV expression) that is restricted to the case when the single-pass absorbance, α0L, is much smaller than the empty cavity losses, π/F [here termed the conventional cavity-limited weak absorption (CCLWA) condition]. This limits the applicability of the technique, primarily its dynamic range and calibration capability. To remedy this, this work derives extended descriptions of Db NICE-OHMS that are not restricted to the CCLWA condition. First, the general principles of Db NICE-OHMS are scrutinized in some detail. Based solely upon a set of general assumptions, predominantly that it is appropriate to linearize the Beer-Lambert law, that the light is modulated to a triplet, and that the Pound-Drever-Hall sidebands are fully reflected, a general description of Db NICE-OHMS that is not limited to any specific restriction on α0L vs. π/F, here referred to as the FULL description, is derived. However, this description constitutes a set of equations to which no closed form solution has been found. Hence, it needs to be solved numerically (by iterations), which is inconvenient. To circumvent this, for the cases when α0L<π/F but without the requirement that the stronger CCLWA condition needs to be fulfilled, a couple of simplified extended expressions that are expressible in closed analytical form, referred to as the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT, have been derived. An analysis based on simulations validates the various descriptions and assesses to which extent they agree. It is shown that in the CCLWA limit, all extended descriptions revert to the CONV expression. The latter one deviates though from the extended ones for α0L around and above 0.1π/F. The two simplified extended descriptions agree

Carbon-13 and proton nuclear magnetic resonance analysis of shale-derived refinery products and jet fuels and of experimental referee broadened-specification jet fuels

NASA Technical Reports Server (NTRS)

Dalling, D. K.; Bailey, B. K.; Pugmire, R. J.

1984-01-01

A proton and carbon-13 nuclear magnetic resonance (NMR) study was conducted of Ashland shale oil refinery products, experimental referee broadened-specification jet fuels, and of related isoprenoid model compounds. Supercritical fluid chromatography techniques using carbon dioxide were developed on a preparative scale, so that samples could be quantitatively separated into saturates and aromatic fractions for study by NMR. An optimized average parameter treatment was developed, and the NMR results were analyzed in terms of the resulting average parameters; formulation of model mixtures was demonstrated. Application of novel spectroscopic techniques to fuel samples was investigated.

Research on spectrum broadening covering visible light of a fiber femtosecond optical frequency comb for absolute frequency measurement

NASA Astrophysics Data System (ADS)

Xing, Shuai; Wu, Tengfei; Li, Shuyi; Xia, Chuanqing; Han, Jibo; Zhang, Lei; Zhao, Chunbo

2018-03-01

As a bridge connecting microwave frequency and optical frequency, femtosecond laser has important significance in optical frequency measurement. Compared with the traditional Ti-sapphire femtosecond optical frequency comb, with the advantages of compact structure, strong anti-interference ability and low cost, the fiber femtosecond optical frequency comb has a wider application prospect. An experiment of spectrum broadening in a highly nonlinear photonic crystal fiber pumped by an Er-fiber mode-locked femtosecond laser is studied in this paper. Based on optical amplification and frequency doubling, the central wavelength of the output spectrum is 780nm and the average power is 232mW. With the femtosecond pulses coupled into two different photonic crystal fibers, the coverage of visible spectrum is up to 500nm-960nm. The spectral shape and width can be optimized by changing the polarization state for satisfying the requirments of different optical frequencies measurement.

Quantum Stark broadening of Ar XV lines. Strong collision and quadrupolar potential contributions

NASA Astrophysics Data System (ADS)

Elabidi, H.; Sahal-Bréchot, S.; Dimitrijević, M. S.

2014-10-01

We present in this paper electron impact broadening for six Ar XV lines using our quantum mechanical formalism and the semiclassical perturbation one. Additionally, our calculations of the corresponding atomic structure data (energy levels and oscillator strengths) and collision strengths are given as well. The lines considered here are divided into two sets: a first set of four lines involving the ground level: 1s22s21S0- 1s22snp 1P1o where 2⩽n⩽5 and a second set of two lines involving excited levels: 1s22s2p 1P1o-1s22s3s 1S0 and 1s22s2p 3P0o-1s22s3s 3S1. An extensive comparison between the quantum and the semiclassical results was performed in order to analyze the reason for differences between quantum and semiclassical results up to the factor of two. It has been shown that the difference between the two results may be due to the evaluation of strong collision contributions by the semiclassical formalism. Except few semiclassical results, the present results are the first to be published. After the recent discovery of the far UV lines of Ar VII in the spectra of very hot central stars of planetary nebulae and white dwarfs, the present -and may be further- results can be used also for the corresponding future spectral analysis.

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.

Reducing attentional capture of emotion by broadening attention: increased global attention reduces early electrophysiological responses to negative stimuli.

PubMed

Gable, Philip A; Harmon-Jones, Eddie

2012-05-01

Decades of research has shown the influence of emotion on attentional capture, and more recently, the influence of emotion on neurophysiological processes related to attentional capture. The current research tested whether some of the earliest neurophysiological underpinnings of emotive attentional processes can be influenced by attentional manipulations of broadening versus narrowing. Previous research has shown that negative affects high in motivational intensity (e.g., disgust, fear) cause a relative narrowing of attentional scope (Gable and Harmon-Jones, 2010a; Easterbrook, 1959). Because of the strong link between motivation and attention, attentional scope should also influence the attentional capture of negative stimuli. The current study manipulated a local attentional scope or global attentional scope, then measured attentional capture towards disgust and neutral pictures using the N1 event-related potential component. Results revealed that a manipulated global attentional scope reduced N1 amplitude towards disgust pictures compared to a manipulated local attentional scope. Copyright © 2012 Elsevier B.V. All rights reserved.

Temperature Dependences for Air-broadened Widths and Shift Coefficients in the 30013 - 00001 and 30012 - 00001 Bands of Carbon Dioxide near 1600 nm

NASA Astrophysics Data System (ADS)

Devi, M.; Predoi-Cross, A.; McKellar, R.; Benner, C.; Miller, C. E.; Toth, R. A.; Brown, L. R.

2008-12-01

Nearly 40 high resolution spectra of air-broadened CO2 recorded at temperatures between 215 and 294 K were analyzed using a multispectrum nonlinear least squares technique to determine temperature dependences of air-broadened half width and air-induced pressure shift coefficients in the 30013-00001 and 30012-00001 bands of 12CO2. Data were recorded with two different Fourier transform spectrometers (Kitt Peak FTS at the National Solar Observatory in Arizona and the Bomem FTS at NRC, Ottawa) with optical path lengths ranging between 25 m and 121 m. The sample pressures varied between 11 torr (pure CO2) and 924 torr (CO2-air) with volume mixing ratios of CO2 in air between ~ 0.015 and 0.11. To minimize systematic errors and increase the accuracy of the retrieved parameters, we constrained the multispectrum nonlinear least squares fittings to use quantum mechanical expressions for the rovibrational energies and intensities rather than retrieving the individual positions and intensities line-by-line. The results suggest minimal vibrational dependence for the temperature dependence coefficients.1 1 A. Predoi-Cross and R. Mckellar are grateful for financial support from the National Sciences and Engineering Research Council of Canada. The research at the Jet Propulsion laboratory (JPL), California Institute of Technology, was performed under contract with National Aeronautics and Space Administration. The support received from the National Science Foundation under Grant No. ATM-0338475 to the College of William and Mary is greatly appreciated. The authors thank Mike Dulick of the National Solar Observatory for his assistance in obtaining the data recorded at Kitt Peak.

Temperature Dependences of Air-Broadening and Shift Parameters in the ν_3 Band of Ozone

NASA Astrophysics Data System (ADS)

Smith, Mary Ann H.; Devi, V. Malathy; Benner, D. Chris

2015-06-01

Line parameter errors can contribute significantly to the total errors in retrievals of terrestrial atmospheric ozone concentration profiles using the strong 9.6-μm band, particularly for nadir-viewing experiments Detailed knowledge of the interfering ozone signal is also needed for retrievals of other atmospheric species in this spectral region. We have determined Lorentz air-broadening and pressure-induced shift coefficients along with their temperature dependences for a number of transitions in the ν_3 fundamental band of 16O_3. These results were obtained by applying the multispectrum nonlinear least-squares fitting technique to a set of 31 high-resolution infrared absorption spectra of O_3 recorded at temperatures between 160 and 300 K with several different room-temperature and coolable sample cells at the McMath-Pierce Fourier transform spectrometer at the National Solar Observatory on Kitt Peak. We compare our results with other available measurements and with the ozone line parameters in the HITRAN database. J.~Worden et al., J.~Geophys.~Res. 109 (2004) 9308-9319. R.~Beer et al., Geophys.~Res.~Lett. 35 (2008) L09801. D.~Chris Benner et al., JQSRT 53 (1995) 705-721. Rothman et al., J. Quant. Spectrosc. Radiat. Transfer 130 (2013) 4. JQSRT 130 (2013) 4-50.

The use of recombinant factor VIIa (NovoSeven) for treatment of active or impending bleeding in brain injury: broadening the indications.

PubMed

Yusim, Yakov; Perel, Azriel; Berkenstadt, Haim; Attia, Moshe; Knoller, Nachshon; Sidi, Avner

2006-11-01

We report three patients with severe traumatic brain injury, both open and closed, who were treated with recombinant activated factor VII. This treatment was given in a desperate, last-ditch effort to save the life of patient 1, as a preventive or early treatment of a developing hematoma in patient 2, and as treatment of a threatening hematoma in patient 3. One of the three patients survived. During the past few years we have broadened the indications for recombinant activated factor VII and started using it as a preventive measure rather than as a "last line of defense." However, the potential complications of disseminated intravascular coagulation and thrombotic events, as well as the cost-effectiveness in view of the available evidence-based medicine, should be considered.

Spectral broadening of characteristic γ-ray emission peaks from 12C(3He,pγ)14N reactions in fusion plasmas.

PubMed

Tardocchi, M; Nocente, M; Proverbio, I; Kiptily, V G; Blanchard, P; Conroy, S; Fontanesi, M; Grosso, G; Kneupner, K; Lerche, E; Murari, A; Cippo, E Perelli; Pietropaolo, A; Syme, B; Van Eester, D; Gorini, G

2011-11-11

The spectral broadening of characteristic γ-ray emission peaks from the reaction (12)C((3)He,pγ)(14)N was measured in D((3)He) plasmas of the JET tokamak with ion cyclotron resonance heating tuned to the fundamental harmonic of (3)He. Intensities and detailed spectral shapes of γ-ray emission peaks were successfully reproduced using a physics model combining the kinetics of the reacting ions with a detailed description of the nuclear reaction differential cross sections for populating the L1-L8 (14)N excitation levels yielding the observed γ-ray emission. The results provide a paradigm, which leverages knowledge from areas of physics outside traditional plasma physics, for the development of nuclear radiation based methods for understanding and controlling fusion burning plasmas.

Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jinhyun; Yim, Sanggyu, E-mail: sgyim@kookmin.ac.kr

2012-10-15

Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughnessmore » and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.« less

The influence of psychological resilience on the relation between automatic stimulus evaluation and attentional breadth for surprised faces.

PubMed

Grol, Maud; De Raedt, Rudi

2015-01-01

The broaden-and-build theory relates positive emotions to resilience and cognitive broadening. The theory proposes that the broadening effects underly the relation between positive emotions and resilience, suggesting that resilient people can benefit more from positive emotions at the level of cognitive functioning. Research has investigated the influence of positive emotions on attentional broadening, but the stimulus in the target of attention may also influence attentional breadth, depending on affective stimulus evaluation. Surprised faces are particularly interesting as they are valence ambiguous, therefore, we investigated the relation between affective evaluation--using an affective priming task--and attentional breadth for surprised faces, and how this relation is influenced by resilience. Results show that more positive evaluations are related to more attentional broadening at high levels of resilience, while this relation is reversed at low levels. This indicates that resilient individuals can benefit more from attending to positively evaluated stimuli at the level of attentional broadening.

Integrated system for production of neutronics and photonics calculational constants. Program SIGMA1 (Version 77-1): Doppler broaden evaluated cross sections in the Evaluated Nuclear Data File/Version B (ENDF/B) format

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cullen, D.E.

1977-01-12

A code, SIGMA1, has been designed to Doppler broaden evaluated cross sections in the ENDF/B format. The code can only be applied to tabulated data that vary linearly in energy and cross section between tabulated points. This report describes the methods used in the code and serves as a user's guide to the code.

Challenge of goodness: twelve humanitarian proposals based on the experience of 1991-1995 wars in Croatia and Bosnia and Herzegovina.

PubMed

Lang, S

1998-03-01

Based on the 1991-1995 war experience of peoples of Croatia and Bosnia and Herzegovina, I made twelve proposals regarding the following aspects of health, humanitarian work, and human rights: 1. Broadening of the WHO definition of health by including spiritual well-being (absence of hatred) in it, 2. Inclusion of the term genocide into the Index Medicus (MeSH), 3. Establishment of concepts of prevention of hate, 4. Right to a home, 5. Right of civilians to participate in defense and renewal, 6. Right to deliberation from enslavement and right to find out the fate of missing persons, 7. Global hospital, 8. Monitoring of prisoner-of-war camps, 9. Refugee camps, 10. Providing of care for the abandoned - a new category of people suffering in war, 11. Introduction of the Helping Hand concept, 12. Organization of the Red Cross Forum after the cessation of hostilities. The fundamental objective was to establish the legitimacy of honesty in practice, regulative social mechanisms, and science.

Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption

NASA Astrophysics Data System (ADS)

Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

2016-05-01

Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3

The California State University Louis Stokes Alliance for Minority Participation (CSU-LSAMP): A Collaborative, Comprehensive Approach to Broadening Participation in STEM.

NASA Astrophysics Data System (ADS)

Hammersley, L. C.

2016-12-01

The National Science Foundation's Louis Stokes Alliances for Minority Participation (LSAMP) program supports alliances of institutions in their efforts to broaden participation in STEM and diversify the STEM workforce. There are currently 42 LSAMP alliances across the nation. Formed in 1993, the California State University LSAMP program (CSU-LSAMP) is an alliance of all 23 campuses of the CSU system and serves over 3,000 students per year. The primary goals of CSU-LSAMP are to increase persistence and graduation rates for URM participants, increase the number of STEM degrees awarded by the CSU to URM students, and increase the number of CSU-LSAMP students who advance to STEM graduate study. CSU-LSAMP activities are focused on four objectives - academic support (e.g. supplemental instruction & peer mentoring), support at transition points (e.g. first time freshmen & transfer students), research experiences (including international research experiences), and professional development (e.g. conference presentations & graduate school preparation activities). Financial support is offered in the form of textbook assistance, research stipends, and travel awards. We maintain a structure that allows campuses to tailor their programs to meet the needs of their own student populations but that also ties the Alliance together with a set of common activities, goals and policies. External evaluation of the program shows that our approach has been highly successful and can provide useful lessons for other programs focused on broadening participation. Since 1994, the number of URM students enrolled in STEM disciplines at CSU campuses has more than doubled and the number of STEM degrees to URM students has almost tripled. Persistence and graduation rates for URM students who participate in CSU-LSAMP are almost twice those of URM non-participants and equal to those of non-URM students. Of the students who participated in the past 15 years, 42 percent either earned a post

Applications of statistical and atomic physics to the spectral line broadening and stock markets

NASA Astrophysics Data System (ADS)

Volodko, Dmitriy

The purpose of this investigation is the application of time correlation function methodology on the theoretical research of the shift of hydrogen and hydrogen-like spectral lines due to electrons and ions interaction with the spectral line emitters-dipole ionic-electronic shift (DIES) and the describing a behavior of stock-market in terms of a simple physical model simulation which obeys Levy statistical distribution---the same as that of the real stock-market index. Using Generalized Theory of Stark broadening of electrons in plasma we discovered a new source of the shift of hydrogen and hydrogen-like spectral lines that we called a dipole ionic-electronic shift (DIES). This shift results from the indirect coupling of electron and ion microfields in plasmas which is facilitated by the radiating atom/ion. We have shown that the DIES, unlike all previously known shifts, is highly nonlinear and has a different sign for different ranges of plasma parameters. The most favorable conditions for observing the DIES correspond to plasmas of high densities, but of relatively low temperature. For the Balmer-alpha line of hydrogen with the most favorable observational conditions Ne > 1018 cm-3, T < 2 eV, the DIES has been already confirmed experimentally. Based on the study of the time correlations and of the probability distribution of fluctuations in the stock market, we developed a relatively simple physical model, which simulates the Dow Jones Industrials index and makes short-term (a couple of days) predictions of its trend.

Investigation of broadening and shift of vapour absorption lines of H{sub 2}{sup 16}O in the frequency range 7184 – 7186 cm{sup -1}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadezhdinskii, A I; Pereslavtseva, A A; Ponurovskii, Ya Ya

2014-10-31

We present the results of investigation of water vapour absorption spectra in the 7184 – 7186 cm{sup -1} range that is of particular interest from the viewpoint of possible application of the data obtained for monitoring water vapour in the Earth's stratosphere. The doublet of H{sub 2}{sup 16}O near ν = 7185.596 cm{sup -1} is analysed. The coefficients of broadening and shift of water vapour lines are found in the selected range in mixtures with buffer gases and compared to those obtained by other authors. (laser spectroscopy)

Band-broadening suppressed effect in long turned geometry channel and high-sensitive analysis of DNA sample by using floating electrokinetic supercharging on a microchip.

PubMed

Xu, Zhongqi; Murata, Kenji; Arai, Akihiro; Hirokawa, Takeshi

2010-03-12

A featured microchip owning three big reservoirs and long turned geometry channel was designed to improve the detection limit of DNA fragments by using floating electrokinetic supercharging (FEKS) method. The novel design matches the FEKS preconcentration needs of a large sample volume introduction with electrokinetic injection (EKI), as well as long duration of isotachophoresis (ITP) process to enrich low concentration sample. In the curved channel [ approximately 45.6 mm long between port 1 (P1) and the intersection point of two channels], EKI and ITP were performed while the side port 3 (P3) was electrically floated. The turn-induced band broadening with or without ITP process was investigated by a computer simulation (using CFD-ACE+ software) when the analytes traveling through the U-shaped geometry. It was found that the channel curvature determined the extent of band broadening, however, which could be effectively eliminated by the way of ITP. After the ITP-stacked zones passed the intersection point from P1, they were rapidly destacked for separation and detection from ITP to zone electrophoresis by using leading ions from P3. The FEKS carried on the novel chip successfully contributed to higher sensitivities of DNA fragments in comparison with our previous results realized on either a single channel or a cross microchip. The analysis of low concentration 50 bp DNA step ladders (0.23 mugml after 1500-fold diluted) was achieved with normal UV detection at 260 nm. The obtained limit of detections (LODs) were on average 100 times better than using conventional pinched injection, down to several ngml for individual DNA fragment.

Broadening the Cloaking Bandwidth with Non-Foster Metasurfaces

NASA Astrophysics Data System (ADS)

Chen, Pai-Yen; Argyropoulos, Christos; Alù, Andrea

2013-12-01

We introduce the concept and practical design of broadband, ultrathin cloaks based on non-Foster, negatively capacitive metasurfaces. By using properly tailored, active frequency-selective screens conformal to an object, within the realm of a practical realization, we show that it is possible to drastically reduce the scattering over a wide frequency range in the microwave regime, orders of magnitude broader than any available passive cloaking technology. The proposed active cloak may impact not only invisibility and camouflaging, but also practical antenna and sensing applications.

Microbial Culturomics Broadens Human Vaginal Flora Diversity: Genome Sequence and Description of Prevotella lascolaii sp. nov. Isolated from a Patient with Bacterial Vaginosis.

PubMed

Diop, Khoudia; Diop, Awa; Levasseur, Anthony; Mediannikov, Oleg; Robert, Catherine; Armstrong, Nicholas; Couderc, Carine; Bretelle, Florence; Raoult, Didier; Fournier, Pierre-Edouard; Fenollar, Florence

2018-03-01

Microbial culturomics is a new subfield of postgenomic medicine and omics biotechnology application that has broadened our awareness on bacterial diversity of the human microbiome, including the human vaginal flora bacterial diversity. Using culturomics, a new obligate anaerobic Gram-stain-negative rod-shaped bacterium designated strain khD1 T was isolated in the vagina of a patient with bacterial vaginosis and characterized using taxonogenomics. The most abundant cellular fatty acids were C 15:0 anteiso (36%), C 16:0 (19%), and C 15:0 iso (10%). Based on an analysis of the full-length 16S rRNA gene sequences, phylogenetic analysis showed that the strain khD1 T exhibited 90% sequence similarity with Prevotella loescheii, the phylogenetically closest validated Prevotella species. With 3,763,057 bp length, the genome of strain khD1 T contained (mol%) 48.7 G + C and 3248 predicted genes, including 3194 protein-coding and 54 RNA genes. Given the phenotypical and biochemical characteristic results as well as genome sequencing, strain khD1 T is considered to represent a novel species within the genus Prevotella, for which the name Prevotella lascolaii sp. nov. is proposed. The type strain is khD1 T ( = CSUR P0109, = DSM 101754). These results show that microbial culturomics greatly improves the characterization of the human microbiome repertoire by isolating potential putative new species. Further studies will certainly clarify the microbial mechanisms of pathogenesis of these new microbes and their role in health and disease. Microbial culturomics is an important new addition to the diagnostic medicine toolbox and warrants attention in future medical, global health, and integrative biology postgraduate teaching curricula.

Extensive scanning of the calpain-3 gene broadens the spectrum of LGMD2A phenotypes.

PubMed

Piluso, G; Politano, L; Aurino, S; Fanin, M; Ricci, E; Ventriglia, V M; Belsito, A; Totaro, A; Saccone, V; Topaloglu, H; Nascimbeni, A C; Fulizio, L; Broccolini, A; Canki-Klain, N; Comi, L I; Nigro, G; Angelini, C; Nigro, V

2005-09-01

The limb girdle muscular dystrophies (LGMD) are a heterogeneous group of Mendelian disorders highlighted by weakness of the pelvic and shoulder girdle muscles. Seventeen autosomal loci have been so far identified and genetic tests are mandatory to distinguish among the forms. Mutations at the calpain 3 locus (CAPN3) cause LGMD type 2A. To obtain unbiased information on the consequences of CAPN3 mutations. 530 subjects with different grades of symptoms and 300 controls. High throughput denaturing HPLC analysis of DNA pools. 141 LGMD2A cases were identified, carrying 82 different CAPN3 mutations (45 novel), along with 18 novel polymorphisms/variants. Females had a more favourable course than males. In 94% of the more severely affected patient group, the defect was also discovered in the second allele. This proves the sensitivity of the approach. CAPN3 mutations were found in 35.1% of classical LGMD phenotypes. Mutations were also found in 18.4% of atypical patients and in 12.6% of subjects with high serum creatine kinase levels. A non-invasive and cost-effective strategy, based on the high throughput denaturing HPLC analysis of DNA pools, was used to obtain unbiased information on the consequences of CAPN3 mutations in the largest genetic study ever undertaken. This broadens the spectrum of LGMD2A phenotypes and sets the carrier frequency at 1:103.

An International Coastline Collaboratory to Broaden Scientific Impacts of a Subduction Zone Observatory

NASA Astrophysics Data System (ADS)

Bodin, P.

2015-12-01

A global Subduction Zone Observatory (SZO) presents an exciting opportunity to broaden involvement in scientific research and to ensure multidisciplinary impact. Most subduction zones feature dynamic interactions of the seafloor, the coastline, and the onshore environments also being perturbed by global climate change. Tectonic deformation, physical environment changes (temperature and chemistry), and resulting ecological shifts (intertidal population redistribution, etc.) are all basic observables for important scientific investigation. Yet even simple baseline studies like repeated transects of intertidal biological communities are rare. A coordinated program of such studies would document the local variability across time and spatial scales, permit comparisons with other subducting coastlines, and extend the reach and importance of other SZO studies. One goal is to document the patterns, and separate the component causes of, coastal uplift and subsidence and ecological response to a subduction zone earthquake using a database of pre-event biological and surveying observations. Observations would be directed by local scientists using students and trained volunteers as observers, under the auspices of local educational entities and using standardized sampling and reporting methods. The observations would be added to the global, Internet-accessible, database for use by the entire scientific community. Data acquisition and analysis supports the educational missions of local schools and universities, forming the basis for educational programs. All local programs would be coordinated by an international panel convened by the SZO. The facility would include a web-hosted lecture series and an annual web conference to aid organization and collaboration. Small grants could support more needy areas. This SZO collaboratory advances not only scientific literacy, but also multinational collaboration and scholarship, and (most importantly) produces important scientific results.

Effect of magnetic field on the optical properties of an inhomogeneously broadened multilevel Λ-system in Rb vapor

NASA Astrophysics Data System (ADS)

Kaur, Paramjit; Wasan, Ajay

2017-03-01

We present a theoretical model, using density matrix approach, to study the effect of external longitudinal and transverse magnetic fields on the optical properties of an inhomogeneously broadened multilevel Λ-system using the D2 line in 85Rb and 87Rb atoms. The presence of closely spaced multiple excited states causes asymmetry in the absorption and dispersion profiles. We observe a wide EIT window with a positive slope at the line center for a stationary atom. While for a moving atom, the linewidth of EIT window reduces and positive dispersion becomes steeper. When magnetic field is applied, our calculations show multiple EIT subwindows that are significantly narrower and shallow than single EIT window. The number of EIT subwindows depend on the orientation of the magnetic field. We also obtain multiple positive dispersive regions for subluminal propagation in the medium. The anomalous dispersion exists in between two subwindows showing the superluminal light propagation. Our theoretical analysis explain the experiments performed by Wei et al. [Phys. Rev. A 72, 023806 (2005)] and Iftiquar et al. [Phys. Rev. A 79, 013808 (2009)].

Hypothermia broadens the therapeutic time window of mesenchymal stem cell transplantation for severe neonatal hypoxic ischemic encephalopathy.

PubMed

Ahn, So Yoon; Chang, Yun Sil; Sung, Dong Kyung; Sung, Se In; Park, Won Soon

2018-05-16

Recently, we have demonstrated that concurrent hypothermia and mesenchymal stem cells (MSCs) transplantation synergistically improved severe neonatal hypoxic ischemic encephalopathy (HIE). The current study was designed to determine whether hypothermia could extend the therapeutic time window of MSC transplantation for severe neonatal HIE. To induce HIE, newborn rat pups were exposed to 8% oxygen for 2 h following unilateral carotid artery ligation on postnatal day (P) 7. After approving severe HIE involving >50% of the ipsilateral hemisphere volume, hypothermia (32 °C) for 2 days was started. MSCs were transplanted 2 days after HIE modeling. Follow-up brain MRI, sensorimotor function tests, assessment of inflammatory cytokines in the cerebrospinal fluid (CSF), and histological evaluation of peri-infarction area were performed. HIE induced progressively increasing brain infarction area over time, increased cell death, reactive gliosis and brain inflammation, and impaired sensorimotor function. All these damages observed in severe HIE showed better, robust improvement with a combination treatment of hypothermia and delayed MSC transplantation than with either stand-alone therapy. Hypothermia itself did not significantly reduce brain injury, but broadened the therapeutic time window of MSC transplantation for severe newborn HIE.

Absolute Rovibrational Intensities, Self-Broadening and Self-Shift Coefficients for the X(sup 1) Sigma(+) V=3 (left arrow) V=0 Band (C-12)(O-16)

NASA Technical Reports Server (NTRS)

Chackerian, Charles, Jr.; Freedman, R.; Giver, L. P.; Brown, L. R.

2001-01-01

The rotationless transition moment squared for the x(sup 1) sigma (sup +) v=3 (left arrow) v=0 band of CO is measured to be the absolute value of R (sub 3-0) squared = 1.7127(25)x 10(exp -7) Debye squared. This value is about 8.6 percent smaller than the value assumed for HITRAN 2000. The Herman-Wallis intensity factor of this band is F=1+0.01168(11)m+0.0001065(79)m squared. The determination of self-broadening coefficients is improved with the inclusion of line narrowing; self-shifts are also reported.

Interfacing superconducting qubits and telecom photons via a rare-earth-doped crystal.

PubMed

O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

2014-08-08

We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of π pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered π pulses. We predict total transfer efficiencies on the order of 90%.

SU-E-T-121: Analyzing the Broadening Effect On the Bragg Peak Due to Heterogeneous Geometries and Implementing User-Routines in the Monte-Carlo Code FLUKA in Order to Reduce Computation Time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumann, K; Weber, U; Simeonov, Y

2015-06-15

Purpose: Aim of this study was to analyze the modulating, broadening effect on the Bragg Peak due to heterogeneous geometries like multi-wire chambers in the beam path of a particle therapy beam line. The effect was described by a mathematical model which was implemented in the Monte-Carlo code FLUKA via user-routines, in order to reduce the computation time for the simulations. Methods: The depth dose curve of 80 MeV/u C12-ions in a water phantom was calculated using the Monte-Carlo code FLUKA (reference curve). The modulating effect on this dose distribution behind eleven mesh-like foils (periodicity ∼80 microns) occurring in amore » typical set of multi-wire and dose chambers was mathematically described by optimizing a normal distribution so that the reverence curve convoluted with this distribution equals the modulated dose curve. This distribution describes a displacement in water and was transferred in a probability distribution of the thickness of the eleven foils using the water equivalent thickness of the foil’s material. From this distribution the distribution of the thickness of one foil was determined inversely. In FLUKA the heterogeneous foils were replaced by homogeneous foils and a user-routine was programmed that varies the thickness of the homogeneous foils for each simulated particle using this distribution. Results: Using the mathematical model and user-routine in FLUKA the broadening effect could be reproduced exactly when replacing the heterogeneous foils by homogeneous ones. The computation time was reduced by 90 percent. Conclusion: In this study the broadening effect on the Bragg Peak due to heterogeneous structures was analyzed, described by a mathematical model and implemented in FLUKA via user-routines. Applying these routines the computing time was reduced by 90 percent. The developed tool can be used for any heterogeneous structure in the dimensions of microns to millimeters, in principle even for organic materials like lung

The Geoscience Alliance--A National Network for Broadening Participation of Native Americans in the Geosciences

NASA Astrophysics Data System (ADS)

Dalbotten, D. M.; Berthelote, A. R.

2014-12-01

The Geoscience Alliance is a national alliance of individuals committed to broadening participation of Native Americans in the geosciences. Native Americans in this case include American Indians, Alaska Natives and people of Native Hawai'ian ancestry. Although they make up a large percentage of the resource managers in the country, they are underrepresented in degrees in the geosciences. The Geoscience Alliance (GA) members are faculty and staff from tribal colleges, universities, and research centers; native elders and community members; industry, agency, and corporate representatives; students (K12, undergraduate, and graduate); formal and informal educators; and other interested individuals. The goals of the Geoscience Alliance are to 1) create new collaborations in support of geoscience education for Native American students, 2) establish a new research agenda aimed at closing gaps in our knowledge on barriers and best practices related to Native American participation in the geosciences, 3) increase participation by Native Americans in setting the national research agenda on issues in the geosciences, and particularly those that impact Native lands, 4) provide a forum to communicate educational opportunities for Native American students in the geosciences, and 5) to understand and respect indigenous traditional knowledge. In this presentation, we look at the disparity between numbers of Native Americans involved in careers related to the geosciences and those who are receiving bachelors or graduate degrees in the geosciences. We address barriers towards degree completion in the geosciences, and look at innovative programs that are addressing those barriers.

Extensive scanning of the calpain-3 gene broadens the spectrum of LGMD2A phenotypes

PubMed Central

Piluso, G; Politano, L; Aurino, S; Fanin, M; Ricci, E; Ventriglia, V; Belsito, A; Totaro, A; Saccone, V; Topaloglu, H; Nascimbeni, A; Fulizio, L; Broccolini, A; Canki-Klain, N; Comi, L; Nigro, G; Angelini, C; Nigro, V

2005-01-01

Background: The limb girdle muscular dystrophies (LGMD) are a heterogeneous group of Mendelian disorders highlighted by weakness of the pelvic and shoulder girdle muscles. Seventeen autosomal loci have been so far identified and genetic tests are mandatory to distinguish among the forms. Mutations at the calpain 3 locus (CAPN3) cause LGMD type 2A. Objective: To obtain unbiased information on the consequences of CAPN3 mutations. Patients: 530 subjects with different grades of symptoms and 300 controls. Methods: High throughput denaturing HPLC analysis of DNA pools. Results: 141 LGMD2A cases were identified, carrying 82 different CAPN3 mutations (45 novel), along with 18 novel polymorphisms/variants. Females had a more favourable course than males. In 94% of the more severely affected patient group, the defect was also discovered in the second allele. This proves the sensitivity of the approach. CAPN3 mutations were found in 35.1% of classical LGMD phenotypes. Mutations were also found in 18.4% of atypical patients and in 12.6% of subjects with high serum creatine kinase levels. Conclusions: A non-invasive and cost–effective strategy, based on the high throughput denaturing HPLC analysis of DNA pools, was used to obtain unbiased information on the consequences of CAPN3 mutations in the largest genetic study ever undertaken. This broadens the spectrum of LGMD2A phenotypes and sets the carrier frequency at 1:103. PMID:16141003

Broadening CD4+ and CD8+ T Cell Responses against Hepatitis C Virus by Vaccination with NS3 Overlapping Peptide Panels in Cross-Priming Liposomes

PubMed Central

Filskov, Jonathan; Mikkelsen, Marianne; Hansen, Paul R.; Christensen, Jan P.; Thomsen, Allan R.; Andersen, Peter; Agger, Else Marie

2017-01-01

ABSTRACT Despite the introduction of effective drugs to treat patients with chronic hepatitis C virus (HCV) infection, a vaccine would be the only means to substantially reduce the worldwide disease burden. An incomplete understanding of how HCV interacts with its human host and evades immune surveillance has hampered vaccine development. It is generally accepted that in infected individuals, a narrow repertoire of exhausted T cells is a hallmark of persistent infection, whereas broad, vigorous CD4+ and CD8+ T cell responses are associated with control of acute hepatitis C. We employed a vaccine approach based on a mixture of peptides (pepmix) spanning the entire sequence of HCV nonstructural protein 3 (NS3) in cross-priming cationic liposomes (CAF09) to facilitate a versatile presentation of all possible T cell epitopes, regardless of the HLA background of the vaccine recipient. Here, we demonstrate that vaccination of mice with NS3 pepmix broadens the repertoire of epitope-specific T cells compared to the corresponding recombinant protein (rNS3). Moreover, vaccination with rNS3 induced only CD4+ T cells, whereas the NS3 pepmix induced a far more vigorous CD4+ T cell response and was as potent a CD8+ T cell inducer as an adenovirus-vectored vaccine expressing NS3. Importantly, the cellular responses are dominated by multifunctional T cells, such as gamma interferon-positive (IFN-γ+) tumor necrosis factor alpha-positive (TNF-α+) coproducers, and displayed cytotoxic capacity in mice. In conclusion, we present a novel vaccine approach against HCV, inducing a broadened T cell response targeting both immunodominant and potential subdominant epitopes, which may be key elements to counter T cell exhaustion and prevent chronicity. IMPORTANCE With at least 700,000 annual deaths, development of a vaccine against hepatitis C virus (HCV) has high priority, but the tremendous ability of the virus to dodge the human immune system poses great challenges. Furthermore, many

The Legacy of NASA Astrophysics E/PO: Conducting Professional Development, Developing Key Themes & Resources, and Broadening E/PO Audiences

NASA Astrophysics Data System (ADS)

Lawton, Brandon L.; Smith, Denise A.; Meinke, Bonnie K.; Bartolone, Lindsay; Manning, Jim; Schultz, Gregory R.; NASA Astrophysics E/PO Community

2016-01-01

For the past six years, NASA's Science Mission Directorate (SMD) has coordinated the work of its mission- and program-embedded education and public outreach (E/PO) efforts through four forums representing its four science divisions. The Astrophysics Forum, as the others, has built on SMD's long-standing principle of partnering scientists and educators and embedding E/PO in its missions to encourage and coordinate collaborative efforts to make the most efficient and effective use of NASA resources, personnel, data and discoveries in leveraged ways, in support of the nation's science education. Three priorities established early in the Forum's period of activity were to collaboratively enhance professional development for formal and informal educators, develop key themes & resources centered on astrophysics topics, and broaden the reach of astrophysics E/PO to traditionally underserved audiences in STEM subjects. This presentation will highlight some of the achievements of the Astrophysics E/PO community and Forum in these priority areas. This work constitutes an ongoing legacy--a firm foundation on which the new structure of NASA SMD education efforts will go forward.

CMS proposal for interventional pain management by nurse anesthetists: evidence by proclamation with poor prognosis.

PubMed

Manchikanti, Laxmaiah; Caraway, David L; Falco, Frank J E; Benyamin, Ramsin M; Hansen, Hans; Hirsch, Joshua A

2012-01-01

The Office of Inspector General (OIG), Department of Health and Human Services (HHS), in a 2009 report, showed that unqualified nonphysicians performed 21% of the services. These nonphysicians did not possess the necessary licenses, certifications, credentials, or training to perform the services. Since the time the medical profession was founded, advances in treatments and technology, as well as educational and training standards, have promoted a desire to go beyond the basic scope of practice. Many have sought to broaden the scope of practice through legislative efforts and proclamation rather than education and training. In 2001, President Clinton signed into law a rule that permitted states to "opt out" of the Centers for Medicare and Medicaid Services' (CMS) requirement for nurse anesthetists to be supervised by any physician. Since then, 17 states have adopted this rule. While it was originally intended to help rural areas improve access to care, the opt out rule essentially supports any hospital or organization that seeks to make a profit or cut costs by allowing nurse anesthetists to function as physicians. With the implementation of sweeping health care regulations under the Affordable Care Act (ACA, also popularly known as Obamacare), the future of nurses and other professionals has been empowered. In fact, it has been proposed that medical training may be reduced by 30%, which will in their minds equalize training between nonphysicians and physicians. In 2010, the Federal Trade Commission (FTC) issued an opinion exerting their power to empower CRNAs with unlimited practice, with threats to opposing parties. In the 2013 proposed physician payment rule, CMS is proposing that CRNAs may perform interventional pain management services. Interventional pain management is a medical discipline with defined interventional techniques to be performed by professionals who are well trained and qualified. Without considering the consequences of the lack of education

Unusual continuous dual absorption peaks in Ca-doped BiFeO3 nanostructures for broadened microwave absorption.

PubMed

Li, Zhong-Jun; Hou, Zhi-Ling; Song, Wei-Li; Liu, Xing-Da; Cao, Wen-Qiang; Shao, Xiao-Hong; Cao, Mao-Sheng

2016-05-21

Electromagnetic absorption materials have received increasing attention owing to their wide applications in aerospace, communication and the electronics industry, and multiferroic materials with both polarization and magnetic properties are considered promising ceramics for microwave absorption application. However, the insufficient absorption intensity coupled with the narrow effective absorption bandwidth has limited the development of high-performance multiferroic materials for practical microwave absorption. To address such issues, in the present work, we utilize interfacial engineering in BiFeO3 nanoparticles via Ca doping, with the purpose of tailoring the phase boundary. Upon Ca-substitution, the co-existence of both R3c and P4mm phases has been confirmed to massively enhance both dielectric and magnetic properties via manipulating the phase boundary and the destruction of the spiral spin structure. Unlike the commonly reported magnetic/dielectric hybrid microwave absorption composites, Bi0.95Ca0.05FeO3 has been found to deliver unusual continuous dual absorption peaks at a small thickness (1.56 mm), which has remarkably broadened the effective absorption bandwidth (8.7-12.1 GHz). The fundamental mechanisms based on the phase boundary engineering have been discussed, suggesting a novel platform for designing advanced multiferroic materials with wide applications.

Matrix Methods for Solving Hartree-Fock Equations in Atomic Structure Calculations and Line Broadening

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez, Thomas; Nagayama, Taisuke; Fontes, Chris

Atomic structure of N-electron atoms is often determined by solving the Hartree-Fock equations, which are a set of integro-differential equations. The integral part of the Hartree-Fock equations treats electron exchange, but the Hartree-Fock equations are not often treated as an integro-differential equation. The exchange term is often approximated as an inhomogeneous or an effective potential so that the Hartree-Fock equations become a set of ordinary differential equations (which can be solved using the usual shooting methods). Because the Hartree-Fock equations are an iterative-refinement method, the inhomogeneous term relies on the previous guess of the wavefunction. In addition, there are numericalmore » complications associated with solving inhomogeneous differential equations. This work uses matrix methods to solve the Hartree-Fock equations as an integro-differential equation. It is well known that a derivative operator can be expressed as a matrix made of finite-difference coefficients; energy eigenvalues and eigenvectors can be obtained by using linear-algebra packages. The integral (exchange) part of the Hartree-Fock equation can be approximated as a sum and written as a matrix. The Hartree-Fock equations can be solved as a matrix that is the sum of the differential and integral matrices. We compare calculations using this method against experiment and standard atomic structure calculations. This matrix method can also be used to solve for free-electron wavefunctions, thus improving how the atoms and free electrons interact. Here, this technique is important for spectral line broadening in two ways: it improves the atomic structure calculations, and it improves the motion of the plasma electrons that collide with the atom.« less

Matrix Methods for Solving Hartree-Fock Equations in Atomic Structure Calculations and Line Broadening

DOE PAGES

Gomez, Thomas; Nagayama, Taisuke; Fontes, Chris; ...

2018-04-23

Atomic structure of N-electron atoms is often determined by solving the Hartree-Fock equations, which are a set of integro-differential equations. The integral part of the Hartree-Fock equations treats electron exchange, but the Hartree-Fock equations are not often treated as an integro-differential equation. The exchange term is often approximated as an inhomogeneous or an effective potential so that the Hartree-Fock equations become a set of ordinary differential equations (which can be solved using the usual shooting methods). Because the Hartree-Fock equations are an iterative-refinement method, the inhomogeneous term relies on the previous guess of the wavefunction. In addition, there are numericalmore » complications associated with solving inhomogeneous differential equations. This work uses matrix methods to solve the Hartree-Fock equations as an integro-differential equation. It is well known that a derivative operator can be expressed as a matrix made of finite-difference coefficients; energy eigenvalues and eigenvectors can be obtained by using linear-algebra packages. The integral (exchange) part of the Hartree-Fock equation can be approximated as a sum and written as a matrix. The Hartree-Fock equations can be solved as a matrix that is the sum of the differential and integral matrices. We compare calculations using this method against experiment and standard atomic structure calculations. This matrix method can also be used to solve for free-electron wavefunctions, thus improving how the atoms and free electrons interact. Here, this technique is important for spectral line broadening in two ways: it improves the atomic structure calculations, and it improves the motion of the plasma electrons that collide with the atom.« less

Integrating Intercultural and Communicative Objectives in the Foreign Language Class: A Proposal for the Integration of Two Models

ERIC Educational Resources Information Center

Borghetti, Claudia

2013-01-01

The "intercultural turn" of the 1990s brought about the introduction of the terms "Foreign Language Education" and "Intercultural Foreign Language Education" (IFLE) in place of "language teaching". These terms broaden the aims of language education to include students' intercultural competence (IC),…

SU-F-J-142: Proposed Method to Broaden Inclusion Potential of Patients Able to Use the Calypso Tracking System in Prostate Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fiedler, D; Kuo, H; Bodner, W

2016-06-15

Purpose: To introduce a non-standard method of patient setup, using BellyBoard immobilization, to better utilize the localization and tracking potential of an RF-beacon system with EBRT for prostate cancer. Methods: An RF-beacon phantom was imaged using a wide bore CT scanner, both in a standard level position and with a known rotation (4° pitch and 7.5° yaw). A commercial treatment planning system (TPS) was used to determine positional coordinates of each beacon, and the centroid of the three beacons for both setups. For each setup at the Linac, kV AP and Rt Lateral images were obtained. A full characterization ofmore » the RF-beacon system in clinical mode was completed for various beacons’ array-to-centroid distances, which includes vertical, lateral, and longitudinal offset data, as well as pitch and yaw offset measurements for the tilted phantom. For the single patient who has been setup using the proposed BellyBoard method, a supine simulation was first obtained. When abdominal protrusion was found to be exceeding the limits of the RF-Beacon system through distance-based analysis in the TPS, the patient is re-simulated prone with the BellyBoard. Array to centroid distance is measured again in the TPS, and if found to be within the localization or tracking region it is applied. Results: Characterization of limitations for the RF-beacon system in clinical mode showed acceptable consistency of offset determination for phantom setup accuracy. The nonstandard patient setup method reduced the beacons’ centroid-to-array distance by 8.32cm, from 25.13cm to 16.81cm; completely out of tracking range (greater than 20cm) to within setup tracking range (less than 20cm). Conclusion: Using the RF-beacon system in combination with this novel patient setup can allow patients who would otherwise not be candidates for beacon enhanced EBRT to now be able to benefit from the reduced PTV margins of this treatment method.« less

Measured Early Lateral Energy Fractions in Concert Halls and Opera Houses

NASA Astrophysics Data System (ADS)

BARRON, M.

2000-04-01

In the 30 years since early lateral reflections were first suggested as important for concert halls, spatial impression and source broadening have become almost universally accepted as essential characteristics of halls with good acoustics. Two objective measures of source broadening have been proposed. Measured values of the best defined of these measures, the early lateral energy fraction (LF), are considered here. Results from two independent measurement surveys are discussed. Comparisons of LF values by hall show a significant link between hall mean LF and hall width. There is however considerable overlap between measured LF values in different halls so the relevance of describing halls by their mean early lateral energy fraction values is questionable. The behaviour of LF values within auditoria is discussed for different concert hall plan forms and within opera houses. A measure of source broadening including sound level is proposed and results considered in the context of auditorium design.

A New Norm: Using Social Science to Create Disruptive Innovations for Broadening Participation in Physics

NASA Astrophysics Data System (ADS)

Smith, Jessi L.

2016-03-01

Norms often operate outside conscious awareness and limit broad participation in physics and STEM fields more generally. This presentation identifies several of these norms and provides empirically tested disruptions at three academic points: faculty, graduate, and undergraduate. First, is a focus on broadening the participation of women science faculty through an intervention aimed at supporting faculty search committees. Using a randomized control trail design, results show searches in the intervention were 6.3 times more likely to make an offer to a woman candidate, and these women were 5.8 times more likely to accept the offer from an intervention search. A diverse faculty can help disrupt the norms of their field's understanding about brilliance and effort, which can appeal to -or repel- potential graduate students. Using a randomized control trial design, recruitment materials for a science graduate program were manipulated to emphasize effort versus innate ability as the norm. Results show emphasizing effort as normal to achieve success in the male-dominated graduate program elevated women's motivation to purse and persist in graduate studies. Of course, before a student will consider graduate school, they must see themselves as a scientist. Data from a survey at three universities showed undergraduate women in physics lab classes were less likely to identify as a scientist when they were concerned about being stereotyped and could not see how physics was useful or helpful to society. Identifying and disrupting social norms can help create an inclusive learning and working context with far-reaching benefits. National Science Foundation Award HRD-1208831 and HRD-1036767.

Broadening of spectral lines of CO2, N2O , H2CO, HCN, and H2S by pressure of gases dominant in planetary atmospheres (H2, He and CO2)

NASA Astrophysics Data System (ADS)

Samuels, Shanelle; Gordon, Iouli; Tan, Yan

2018-01-01

HITRAN1,2 is a compilation of spectroscopic parameters that a variety of computer codes use to predict and simulate the transmission and emission of light in planetary atmospheres. The goal of this project is to add to the potential of the HITRAN database towards the exploration of the planetary atmospheres by including parameters describing broadening of spectral lines by H2, CO2, and He. These spectroscopic data are very important for the study of the hydrogen and helium-rich atmospheres of gas giants as well as rocky planets with volcanic activities, including Venus and Mars, since their atmospheres are dominated by CO2. First step in this direction was accomplished by Wilzewski et al.3 where this was done for SO2, NH3, HF, HCl, OCS and C2H2. The molecules investigated in this work were CO2, N2O, H2CO, HCN and H2S. Line-broadening coefficients, line shifts and temperature-dependence exponents for transitions of these molecules perturbed by H2, CO2 and He have been assembled from available peer-reviewed experimental and theoretical sources. The data was evaluated and the database was populated with these data and their extrapolations/interpolations using semi-empirical models that were developed to this end.Acknowledgements: Financial support from NASA PDART grant NNX16AG51G and the Smithsonian Astrophysical Observatory Latino Initiative Program from the Latino Initiatives Pool, administered by the Smithsonian Latino Center is gratefully acknowledged.References: 1. HITRAN online http://hitran.org/2. Gordon, I.E., Rothman, L.S., Hill, C., Kochanov, R.V., Tan, Y., et al., 2017. The HITRAN2016 Molecular Spectroscopic Database. J. Quant. Spectrosc. Radiat. Transf. doi:10.1016/j.jqsrt.2017.06.0383. Wilzewski, J.S., Gordon, I.E., Kochanov, R. V., Hill, C., Rothman, L.S., 2016. H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2. J. Quant. Spectrosc. Radiat

Capitalizing on Education and Outreach (E/O) Expertise to Broaden Impacts (Invited)

NASA Astrophysics Data System (ADS)

Girguis, P. R.; Herren, C.; Decharon, A.

2010-12-01

Academic scientists have a number of avenues through which they can participate in education and outreach (E/O) programs to address the mandate for broader impacts. As a principal investigator (PI) at an R1 institution, I (Girguis) have both developed and participated in a variety of E/O programs that span the spectrum from ad hoc groups (e.g. informal high school internships in my laboratory) to regional efforts (e.g. Harvard’s Microbial Science Initiative) and national organizations (e.g. RIDGE 2000; Centers for Ocean Sciences Education Excellence, COSEE). Each of these E/O efforts required varying degrees of preparation and participation by my laboratory members (e.g. graduate students and postdoctoral researchers) and I, and yielded different outcomes and products. Ad hoc programs typically require a higher degree of effort on the part of the PI and have a high, though local, impact on the audience. These programs can be personally rewarding for the PI, who likely has played a major role in developing the program. In contrast, working with regional and national groups requires PIs to understand the nature of each program to successfully integrate within the existing structure. The net time and effort invested by scientists in larger-scale E/O efforts may be equal to that of ad hoc programs. However, interaction with high-quality program facilitators ensures that the outcomes are grounded in best educational practices and that outputs are educator-vetted, well maintained (online or through publications), and broadly disseminated. In addition, program facilitators also collect and analyze evaluation data to provide constructive feedback to PIs, enabling the latter to refine their presentation styles and content levels to improve future E/O efforts. Thus involvement with larger programs can effectively broaden one’s impact. During this presentation, we will present one scientist’s perspective on the advantages and limitations of these different modes of E

Speed-Dependent Broadening and Line-Mixing in CH_4 Perturbed by Air Near 1.64 μm for the French/german Climate Mission MERLIN

NASA Astrophysics Data System (ADS)

Delahaye, Thibault; Tran, Thi Ngoc Ha; Reed, Zachary; Maxwell, Stephen E.; Hodges, Joseph

2015-06-01

Climate change is one of the greatest challenges presently facing mankind, and methane is one of the most powerful anthropogenic greenhouse gases. For a better understanding of future climate trends, a satellite dedicated to the measurements of atmospheric methane is under joint development by the French and German space research centers (CNES and DLR). The so-called MERLIN mission (Methane Remote Sensing Lidar Mission, 2019) aims at providing global information on atmospheric methane concentration with a relative uncertainty less than 2% and with a spatial resolution of 50 km Such spectroscopic monitoring of gases in the atmosphere of the Earth, requires a precise description of absorption lines shapes that goes beyond the usual Voigt profile (VP). In the case of methane, the differences between the measured profiles and those given by the VP can be very important, making the VP completely incompatible with the reliable detection of sources and sinks from space. In this work, we present the first results on the modeling of methane lines broadened by air in the 1.64 μm region and the associated spectroscopic parameters, taking into account various collisional effects between molecules that are neglected by the VP: collisional interference between the lines (line-mixing), collision-induced velocity changes (Dicke narrowing effect) and speed dependence of the collisional broadening and shifting. These results were obtained by simultaneously fitting the model parameters to high sensitivity and high-resolution cavity ring-down spectroscopy (CRDS) spectra recorded at the National Institute of Standards and Technology (NIST) over a wide pressure range (5 to 100 kPa). These spectroscopic data and the associated model to calculate the spectrum absorption coefficient will be then used to analyze ground-based atmospheric spectra at the TCCON facility in Park Falls, Wisconsin. C. Kiemle, M. Quatrevalet, G. Ehret et al., Atmos. Meas. Tech. 4 (2011) H. Tran, J.-M. Hartmann, G

Line shape parameters of PH3 transitions in the Pentad near 4-5 μm: Self-broadened widths, shifts, line mixing and speed dependence

NASA Astrophysics Data System (ADS)

Malathy Devi, V.; Benner, D. Chris; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

2014-08-01

Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (∼2-50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C3v symmetry in general, and of PH3

Doping dependent blue shift and linewidth broadening of intersubband absorption in non-polar m-plane AlGaN/GaN multiple quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotani, Teruhisa, E-mail: tkotani@iis.u-tokyo.ac.jp; Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505; Advanced Technology Research Laboratories, Sharp Corporation, 2613-1 Ichinomoto-cho, Tenri, Nara 632-8567

2015-09-14

Blue shift and broadening of the absorption spectra of mid-infrared intersubband transition in non-polar m-plane AlGaN/GaN 10 quantum wells were observed with increasing doping density. As the doping density was increased from 6.6 × 10{sup 11} to 6.0 × 10{sup 12 }cm{sup −2} per a quantum well, the intersubband absorption peak energy shifted from 274.0 meV to 302.9 meV, and the full width at half maximum increased from 56.4 meV to 112.4 meV. Theoretical calculations reveal that the blue shift is due to many body effects, and the intersubband linewidth in doped AlGaN/GaN QW is mainly determined by scattering due to interface roughness, LO phonons, and ionized impurities.

Correlation Of Ortho-Positronium Intensity With Doppler Broadening For Rubber Above And Below The Glass Transition Temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Towry, Amanda; Quarles, C. A.

Previous research has demonstrated a correlation between the Doppler broadening S parameter and the intensity of the ortho-positronium lifetime component in polymers that depends on the composition of the polymer. On the other hand, rubber polymers do not show this correlation and behave more like liquids for which the S parameter is essentially independent of the ortho-positronium intensity. The bubble model has been suggested as an explanation of the lack of correlation in analogy with liquids, but the bubble model applied to rubber is controversial. There are two important differences between the rubber and the polymers samples: first, the rubbermore » samples at room temperature were all above the glass transition temperature (T{sub G}). Second, the rubber samples all contained sulfur and were vulcanized. These differences were investigated by first measuring the S parameter for six rubber samples below T{sub G} where the bubble model would not be expected to work. Second, raw rubber samples that did not contain any sulfur and were unvulcanized were studied at room temperature. The results show that the lack of correlation between the S parameter and the ortho-positronium intensity previously observed for vulcanized rubber is due to the inhibition of positronium formation by the sulfur in the vulcanized rubber samples rather than to the rubber being above T{sub G}.« less

Near-side jet peak broadening in Pb-Pb collisions at √{sNN } = 2.76 TeV

NASA Astrophysics Data System (ADS)

Kofarago, Monika; Alice Collaboration

2017-08-01

Two-particle angular correlation measurements are sensitive probes of the interactions of particles with the medium formed in heavy-ion collisions. Such measurements are done by determining the distribution of the relative pseudo-rapidity (Δη) and azimuthal angle (Δϕ) of particles with respect to a higher pT trigger particle (1 broadening of the near-side peak in the Δη direction is observed from peripheral to central collisions, while in the Δφ direction the peak is almost independent of centrality. For the 10% most central events, a departure from the Gaussian shape is also observed at low transverse momentum (1

Targeting of non-dominant antigens as a vaccine strategy to broaden T-cell responses during chronic viral infection.

PubMed

Holst, Peter J; Jensen, Benjamin A H; Ragonnaud, Emeline; Thomsen, Allan R; Christensen, Jan P

2015-01-01

In this study, we compared adenoviral vaccine vectors with the capacity to induce equally potent immune responses against non-dominant and immunodominant epitopes of murine lymphocytic choriomeningitis virus (LCMV). Our results demonstrate that vaccination targeting non-dominant epitopes facilitates potent virus-induced T-cell responses against immunodominant epitopes during subsequent challenge with highly invasive virus. In contrast, when an immunodominant epitope was included in the vaccine, the T-cell response associated with viral challenge remained focussed on that epitope. Early after challenge with live virus, the CD8+ T cells specific for vaccine-encoded epitopes, displayed a phenotype typically associated with prolonged/persistent antigenic stimulation marked by high levels of KLRG-1, as compared to T cells reacting to epitopes not included in the vaccine. Notably, this association was lost over time in T cells specific for the dominant T cell epitopes, and these cells were fully capable of expanding in response to a new viral challenge. Overall, our data suggests a potential for broadening of the antiviral CD8+ T-cell response by selecting non-dominant antigens to be targeted by vaccination. In addition, our findings suggest that prior adenoviral vaccination is not likely to negatively impact the long-term and protective immune response induced and maintained by a vaccine-attenuated chronic viral infection.

Spin conversion of positronium in NiO/Al2O3 catalysts observed by coincidence Doppler broadening technique

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Chen, Z. Q.; Wang, S. J.; Kawasuso, A.; Morishita, N.

2010-07-01

High-purity NiO/Al2O3 catalysts were prepared by mixing NiO and γ-Al2O3 nanopowders. X-ray diffraction patterns were measured to characterize the grain size and crystalline phase of the nanopowders. Positron-annihilation spectroscopy was used to study the microstructure and surface properties of the pores inside the NiO/Al2O3 catalysts. The positron lifetime spectrum comprises two short and two long lifetime components. The two long lifetimes τ3 and τ4 correspond to ortho-positronium (o-Ps) annihilated in microvoids and large pores, respectively. With increasing NiO content in the NiO/Al2O3 catalysts, both τ4 and its intensity I4 show continuous decrease. Meanwhile, the para-positronium (p-Ps) intensity, obtained from coincidence Doppler broadening spectra, increases gradually with NiO content. The different variation in o-Ps and p-Ps intensity suggests the ortho-para conversion of positronium in NiO/Al2O3 catalysts. X-ray photoelectron spectroscopy shows that Ni mainly exists in the form of NiO. The electron-spin-resonance measurements reveal that the ortho-para conversion of Ps is induced by the unpaired electrons of the paramagnetic centers of NiO.