Sample records for absolute oscillator strengths

  1. The realization of the dipole (γ, γ) method and its application to determine the absolute optical oscillator strengths of helium.

    PubMed

    Xu, Long-Quan; Liu, Ya-Wei; Kang, Xu; Ni, Dong-Dong; Yang, Ke; Hiraoka, Nozomu; Tsuei, Ku-Ding; Zhu, Lin-Fan

    2015-12-17

    The dipole (γ, γ) method, which is the inelastic x-ray scattering operated at a negligibly small momentum transfer, is proposed and realized to determine the absolute optical oscillator strengths of the vanlence-shell excitations of atoms and molecules. Compared with the conventionally used photoabsorption method, this new method is free from the line saturation effect, which can seriously limit the accuracies of the measured photoabsorption cross sections for discrete transitions with narrow natural linewidths. Furthermore, the Bethe-Born conversion factor of the dipole (γ, γ) method varies much more slowly with the excitation energy than does that of the dipole (e, e) method. Absolute optical oscillator strengths for the excitations of 1s(2) → 1 snp(n = 3-7) of atomic helium have been determined using the high-resolution dipole (γ, γ) method, and the excellent agreement of the present measurements with both those measured by the dipole (e, e) method and the previous theoretical calculations indicates that the dipole (γ, γ) method is a powerful tool to measure the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules.

  2. Where Is the Electronic Oscillator Strength? Mapping Oscillator Strength across Molecular Absorption Spectra.

    PubMed

    Zheng, Lianjun; Polizzi, Nicholas F; Dave, Adarsh R; Migliore, Agostino; Beratan, David N

    2016-03-24

    The effectiveness of solar energy capture and conversion materials derives from their ability to absorb light and to transform the excitation energy into energy stored in free carriers or chemical bonds. The Thomas-Reiche-Kuhn (TRK) sum rule mandates that the integrated (electronic) oscillator strength of an absorber equals the total number of electrons in the structure. Typical molecular chromophores place only about 1% of their oscillator strength in the UV-vis window, so individual chromophores operate at about 1% of their theoretical limit. We explore the distribution of oscillator strength as a function of excitation energy to understand this circumstance. To this aim, we use familiar independent-electron model Hamiltonians as well as first-principles electronic structure methods. While model Hamiltonians capture the qualitative electronic spectra associated with π electron chromophores, these Hamiltonians mistakenly focus the oscillator strength in the fewest low-energy transitions. Advanced electronic structure methods, in contrast, spread the oscillator strength over a very wide excitation energy range, including transitions to Rydberg and continuum states, consistent with experiment. Our analysis rationalizes the low oscillator strength in the UV-vis spectral region in molecules, a step toward the goal of oscillator strength manipulation and focusing.

  3. Assessment of the Accuracy of the Bethe-Salpeter (BSE/GW) Oscillator Strengths.

    PubMed

    Jacquemin, Denis; Duchemin, Ivan; Blondel, Aymeric; Blase, Xavier

    2016-08-09

    Aiming to assess the accuracy of the oscillator strengths determined at the BSE/GW level, we performed benchmark calculations using three complementary sets of molecules. In the first, we considered ∼80 states in Thiel's set of compounds and compared the BSE/GW oscillator strengths to recently determined ADC(3/2) and CC3 reference values. The second set includes the oscillator strengths of the low-lying states of 80 medium to large dyes for which we have determined CC2/aug-cc-pVTZ values. The third set contains 30 anthraquinones for which experimental oscillator strengths are available. We find that BSE/GW accurately reproduces the trends for all series with excellent correlation coefficients to the benchmark data and generally very small errors. Indeed, for Thiel's sets, the BSE/GW values are more accurate (using CC3 references) than both CC2 and ADC(3/2) values on both absolute and relative scales. For all three sets, BSE/GW errors also tend to be nicely spread with almost equal numbers of positive and negative deviations as compared to reference values.

  4. Optical oscillator strengths of the valence-shell excitations of atoms and molecules determined by the dipole ( γ,γ) method

    NASA Astrophysics Data System (ADS)

    Xu, Long-Quan; Liu, Ya-Wei; Xu, Xin; Ni, Dong-Dong; Yang, Ke; Zhu, Lin-Fan

    2017-07-01

    The dipole (γ,γ) method, which is the inelastic X-ray scattering operated at a negligibly small momentum transfer, has been developed to determine the absolute optical oscillator strengths of the valence-shell excitations of atoms and molecules. This new method is free from the line saturation effect, and its Bethe-Born conversion factor varies much more slowly with the excitation energy than that of the dipole (e, e) method. Thus the dipole (γ,γ) method provides a reliable approach to obtain the benchmark optical oscillator strengths of the valence-shell excitations for gaseous atoms and molecules. In this paper, we give a review of the dipole (γ,γ) method and some recent measurements of absolute optical oscillator strengths of gaseous atoms and molecules. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

  5. OSCILLATOR STRENGTHS OF VIBRIONIC EXCITATIONS OF NITROGEN DETERMINED BY THE DIPOLE (γ, γ) METHOD

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

    Liu, Ya-Wei; Kang, Xu; Xu, Long-Quan

    2016-03-10

    The oscillator strengths of the valence-shell excitations of molecular nitrogen have significant applicational values in studies of the Earth's atmosphere and interstellar gases. In this work, the absolute oscillator strengths of the valence-shell excitations of molecular nitrogen in 12.3–13.4 eV were measured by the novel dipole (γ, γ) method, in which the high-resolution inelastic X-ray scattering is operated at a negligibly small momentum transfer and can simulate the photoabsorption process. Because the experimental technique used in the present work is distinctly different from those used previously, the present experimental results give an independent cross-check to previous experimental and theoretical data.more » The excellent coincidence of the present results with the dipole (e, e) and those that were extrapolated indicates that the present oscillator strengths can serve as benchmark data.« less

  6. Oscillator strengths and collision strengths for S v

    NASA Technical Reports Server (NTRS)

    Van Wyngaarden, W. L.; Henry, R. J. W.

    1981-01-01

    Observations of the optical extreme-ultraviolet spectrum of the Jupiter planetary system during the Voyager space mission revealed bright emission lines of some sulfur ions. The spectra of the torus at the orbit of Io are likely to contain S V lines. The described investigation provides oscillator strengths and collision strengths for the first four UV lines. The collision strengths from the ground state to four other excited states are also obtained. Use is made of a two-state calculation which is checked for convergence for some transitions by employing a three-state or a four-state approximation. Target wave functions for S V are calculated so that the oscillator strengths calculated in dipole length and dipole velocity approximations agree within 5%.

  7. Determination of the Oscillator Strengths for the Third and Fourth Vibrational Overtone Transitions in Simple Alcohols

    NASA Astrophysics Data System (ADS)

    Wallberg, Jens; Kjaergaard, Henrik G.

    2017-06-01

    Absolute measurements of the weak transitions require sensitive spectroscopic techniques. With our recently constructed pulsed cavity ring down (CRD) spectrometer, we have recorded the third and fourth vibrational overtone of the OH stretching vibration in a series of simple alcohols: methanol (MeOH), ethanol (EtOH), 1-propanol (1-PrOH), 2-propanol (2-PrOH) and tert-butanol (tBuOH). The CRD setup (in a flow cell configuration) is combined with a conventional FTIR spectrometer to determine the partial pressure of the alcohols from the fundamental transitions of the OH-stretching vibration. The oscillator strengths of the overtone transitions are determined from the integrated absorbances of the overtone spectra and the partial pressures. Furthermore, the oscillator strengths were calculated using vibrational local mode theory with energies and dipole moments calculated at CCSD(T)/aug-cc-pVTZ level of theory. We find a good agreement between the observed and calculated oscillator strengths across the series of alcohols.

  8. Measured oscillator strengths in singly ionized molybdenum

    NASA Astrophysics Data System (ADS)

    Mayo-García, R.; Aragón, C.; Aguilera, J. A.; Ortiz, M.

    2015-11-01

    In this article, 112 oscillator strengths from Mo II have been measured, 79 of which for the first time. The radiative parameters have been obtained by laser-induced breakdown spectroscopy (LIBS). The plasma is produced from a fused glass sample prepared from molybdenum oxide with a Mo atomic concentration of 0.1%. The plasma evolved in air at atmospheric pressure, and measurements were carried out with the following plasma parameters: an electron density of (2.5+/- 0.1)\\cdot {10}17 cm-3 and an electron temperature of 14,400+/- 200 K. In these conditions, a local thermodynamic equilibrium environment and an optically thin plasma were confirmed for the measurements. The relative intensities were placed on an absolute scale by combining branching fractions with the measured lifetimes and by comparing well-known lines using the plasma temperature. Comparisons were made to previously obtained experimental and theoretical values wherever possible.

  9. New Accurate Oscillator Strengths and Electron Excitation Collision Strengths for N I

    NASA Astrophysics Data System (ADS)

    Tayal, S. S.

    2006-03-01

    The nonorthogonal orbitals technique in a multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities of N I lines. The relativistic effects are allowed by means of Breit-Pauli operators. The length and velocity forms of oscillator strengths show good agreement for most transitions. The B-spline R-matrix with pseudostates approach has been used to calculate electron excitation collision strengths and rates. The nonorthogonal orbitals are used for an accurate description of both target wave functions and the R-matrix basis functions. The 24 spectroscopic bound and autoionizing states together with 15 pseudostates are included in the close-coupling expansion. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. Thermally averaged collision strengths have been determined by integrating collision strengths over a Maxwellian distribution of electron energies over a temperature range suitable for the modeling of astrophysical plasmas. The oscillator strengths and thermally averaged collision strengths are presented for transitions between the fine-structure levels of the 2s22p3 4So, 2Do, 2Po, 2s2p4 4P, 2s22p23s 4P, and 2P terms and from these levels to the levels of the 2s22p23p 2So, 4Do, 4Po, 4So, 2Do, 2Po, 2s22p23s 2D, 2s22p24s 4P, 2P, 2s22p23d 2P, 4F, 2F, 4P, 4D, and 2D terms. Thermally averaged collision strengths are tabulated over a temperature range from 500 to 50,000 K.

  10. EXPERIMENTALLY MEASURED RADIATIVE LIFETIMES AND OSCILLATOR STRENGTHS IN NEUTRAL VANADIUM

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

    Holmes, C. E.; Pickering, J. C.; Ruffoni, M. P.

    2016-06-01

    We report a new study of the V i atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24,648 cm{sup −1} and 37,518 cm{sup −1} and oscillator strengths for 208 lines between 3040 and 20000 Å from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. and Lawler et al., and thus serves as a means to verify thosemore » measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000 ± 100 Å. We suggest a correction of 0.18 ± 0.03 dex for these values to bring them into agreement with our results and those of Whaling et al. We also report new measurements of hyperfine structure splitting factors for three odd levels of V i lying between 24,700 and 28,400 cm{sup −1}.« less

  11. Can the oscillator strength of the quantum dot bandgap transition exceed unity?

    NASA Astrophysics Data System (ADS)

    Hens, Z.

    2008-10-01

    We discuss the apparent contradiction between the Thomas-Reiche-Kuhn sum rule for oscillator strengths and recent experimental data on the oscillator strength of the band gap transition of quantum dots. Starting from two simple single electron model systems, we show that the sum rule does not limit this oscillator strength to values below unity, or below the number of electrons in the highest occupied single electron state. The only upper limit the sum rule imposes on the oscillator strength of the quantum dot band gap transition is the total number of electrons in the quantum dot.

  12. Experimental radiative lifetimes, branching fractions, and oscillator strengths of some levels in Co I

    NASA Astrophysics Data System (ADS)

    Wang, Xinghao; Yu, Qi; Li, Qiu; Gao, Yang; Dai, Zhenwen

    2018-04-01

    The radiative lifetime measurements by the time-resolved laser-induced fluorescence technique are reported for 24 levels of Co I with the energy range of 283 45.86-55 922.3 cm-1, amongst which the lifetimes of 20 levels are reported for the first time. The branching fraction measurements by the emission spectrum of a hollow cathode lamp were performed for 11 levels of them together with other two levels reported in the literature, and branching fractions of 39 transitions were obtained. By combining them with lifetime values, the transition probabilities and absolute oscillator strengths of these lines were determined.

  13. Dipole oscillator strength properties and dispersion energies for SiH 4

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Kumar, Mukesh; Meath, William J.

    2003-01-01

    A recommended isotropic dipole oscillator strength distribution (DOSD) has been constructed for the silane (SiH 4) molecule through the use of quantum mechanical constraint techniques and experimental dipole oscillator strength data. The constraints are furnished by experimental molar refractivity data and the Thomas-Reiche-Kuhn sum rule. The DOSD is used to evaluate a variety of isotropic dipole oscillator strength sums, logarithmic dipole oscillator strength sums, and mean excitation energies for the molecule. A pseudo-DOSD for SiH 4 is also presented which is used to obtain reliable results for the isotropic dipole-dipole dispersion energy coefficients C 6, for the interaction of silane with itself and with forty-four other species, and the triple-dipole dispersion energy coefficient C 9 for (SiH 4) 3.

  14. Experimental and theoretical oscillator strengths of Mg I for accurate abundance analysis

    NASA Astrophysics Data System (ADS)

    Pehlivan Rhodin, A.; Hartman, H.; Nilsson, H.; Jönsson, P.

    2017-02-01

    Context. With the aid of stellar abundance analysis, it is possible to study the galactic formation and evolution. Magnesium is an important element to trace the α-element evolution in our Galaxy. For chemical abundance analysis, such as magnesium abundance, accurate and complete atomic data are essential. Inaccurate atomic data lead to uncertain abundances and prevent discrimination between different evolution models. Aims: We study the spectrum of neutral magnesium from laboratory measurements and theoretical calculations. Our aim is to improve the oscillator strengths (f-values) of Mg I lines and to create a complete set of accurate atomic data, particularly for the near-IR region. Methods: We derived oscillator strengths by combining the experimental branching fractions with radiative lifetimes reported in the literature and computed in this work. A hollow cathode discharge lamp was used to produce free atoms in the plasma and a Fourier transform spectrometer recorded the intensity-calibrated high-resolution spectra. In addition, we performed theoretical calculations using the multiconfiguration Hartree-Fock program ATSP2K. Results: This project provides a set of experimental and theoretical oscillator strengths. We derived 34 experimental oscillator strengths. Except from the Mg I optical triplet lines (3p 3P°0,1,2-4s 3S1), these oscillator strengths are measured for the first time. The theoretical oscillator strengths are in very good agreement with the experimental data and complement the missing transitions of the experimental data up to n = 7 from even and odd parity terms. We present an evaluated set of oscillator strengths, gf, with uncertainties as small as 5%. The new values of the Mg I optical triplet line (3p 3P°0,1,2-4s 3S1) oscillator strength values are 0.08 dex larger than the previous measurements.

  15. Dipole oscillator strengths, dipole properties and dispersion energies for SiF4

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Kumar, Mukesh; Meath, William J.

    2003-01-01

    A recommended isotropic dipole oscillator strength distribution (DOSD) has been constructed for the silicon tetrafluoride (SiF4) molecule through the use of quantum mechanical constraint techniques and experimental dipole oscillator strength data. The constraints are furnished by experimental molar refractivity data and the Thomas-Reiche-Kuhn sum rule. The DOSD is used to evaluate a variety of isotropic dipole oscillator strength sums, logarithmic dipole oscillator strength sums and mean excitation energies for the molecule. A pseudo-DOSD for SiF4 is also presented which is used to obtain reliable results for the isotropic dipole-dipole dispersion energy coefficients C6, for the interaction of SiF4 with itself and with 43 other species and the triple-dipole dispersion energy coefficient C9 for (SiF4)3.

  16. New Accurate Oscillator Strengths and Electron Excitation Collision Strengths for N1

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    2006-01-01

    The nonorthogonal orbitals technique in a multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities of N(I) lines. The relativistic effects are allowed by means of Breit-Pauli operators. The length and velocity forms of oscillator strengths show good agreement for most transitions. The B-spline R-matrix with pseudostates approach has been used to calculate electron excitation collision strengths and rates. The nonorthogonal orbitals are used for an accurate description of both target wave functions and the R-matrix basis functions. The 24 spectroscopic bound and autoionizing states together with 15 pseudostates are included in the close-coupling expansion. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. Thermally averaged collision strengths have been determined by integrating collision strength over a Maxwellian distribution of electron energies over a temperature range suitable for the modeling of astrophysical plasmas. The oscillator strengths and thermally averaged collision strengths are presented for transitions between the fine-structure levels of the 2s(sup 2)p(sup 3) (sup 4)S(sup 0), (sup 2)D(sup 0), (sup 2)P(sup 0), 2s2p(sup 4) (sup 4)P, 2s(sup 2)2p(sup 2)3s (sup 4)P, and (sup 2)P terms and from these levels to the levels of the 2s(sup 2)2p(sup 2)3p (sup 2)S(sup 0), (sup 4)D(sup 0), (sup 4)P(sup 0), (sup 4)S(sup 0), (sup 2)D(sup 0), (sup 2)P(sup 0),2s(sup 2)2p(sup 2)3s(sup 2)D, 2s(sup 2)2p(sup 2)4s(sup 4)P, (sup 2)P, 2s(sup 2)2p(sup 2)3d(sup 2)P, (sup 4)F,(sup 2)F,(sup 4)P, (sup 4)D, and (sup 2)D terms. Thermally averaged collision strengths are tabulated over a temperature range from 500 to 50,000 K.

  17. Oscillator strength of symmetry-forbidden d-d absorption of octahedral transition metal complex: theoretical evaluation.

    PubMed

    Saito, Ken; Eishiro, Yoshinori; Nakao, Yoshihide; Sato, Hirofumi; Sakaki, Shigeyoshi

    2012-03-05

    The theoretical evaluation of the oscillator strength of a symmetry-forbidden d-d transition is not easy even nowadays. A new approximate method is proposed here and applied to octahedral complexes [Co(NH(3))(6)](3+) and [Rh(NH(3))(6)](3+) as an example. Our method incorporates the effects of geometry distortion induced by molecular vibration and the thermal distribution of such distorted geometries but does not need the Herzberg-Teller approximation. The calculated oscillator strengths of [Co(NH(3))(6)](3+) agree well with the experimental values in both (1)A(1g) → (1)T(1g) and (1)A(1g) → (1)T(2g) transitions. In the Rh analogue, though the calculated oscillator strengths are somewhat smaller than the experimental values, computational results reproduce well the experimental trends that the oscillator strengths of [Rh(NH(3))(6)](3+) are much larger than those of the Co analogue and the oscillator strength of the (1)A(1g) → (1)T(1g) transition is larger than that of the (1)A(1g) → (1)T(2g) transition. It is clearly shown that the oscillator strength is not negligibly small even at 0 K because the distorted geometry (or the uncertainty in geometry) by zero-point vibration contributes to the oscillator strength at 0 K. These results are discussed in terms of frequency of molecular vibration, extent of distortion induced by molecular vibration, and charge-transfer character involved in the d-d transition. The computational results clearly show that our method is useful in evaluating and discussing the oscillator strength of symmetry-forbidden d-d absorption of transition metal complex.

  18. VizieR Online Data Catalog: Eu III oscillator strengths (Masonkina+, 2002)

    NASA Astrophysics Data System (ADS)

    Masonkina, L. I.; Ryabtsev, A. N.; Ryabchikova, T. A.

    2002-04-01

    The calculations of the spectrum and oscillator strengths for the 4f7-(4f65d+4f66s) Eu III transitions. The calculations were performed with Cowan's RCN-RCG-RCE codes in the single-configuration approximation. The new oscillator strengths were tested by analyzing the Europium abundances using Eu II and Eu III lines in the spectra of hot peculiar stars (α2 CVn is a typical representative) and a cool peculiar stars (β CrB is a typical representative). (3 data files).

  19. Relative Band Oscillator Strengths for Carbon Monoxide: Alpha (1)Pi-Chi (1)Sigma(+) Transitions

    NASA Technical Reports Server (NTRS)

    Federman, S. R.; Menningen, K. L.; Lee, Wei; Stoll, J. B.

    1997-01-01

    Band oscillator strengths for CO transitions between the electronic states A (l)Pi and X(1)Sigma(+) were measured via absorption with a synchrotron radiation source. When referenced to the well-characterized (5,0) band oscillator strength, our relative values for the (7,0) to (11,0) bands are most consistent with the recent experiments of Chan et al. and the theoretical predictions of Kirby & Cooper. Since the results from various laboratory techniques and theory now agree, analyses of interstellar CO based on absorption from A-X bands are no longer hindered by uncertainties in oscillator strength.

  20. Level Energies, Oscillator Strengths and Lifetimes for Transitions in Pb IV

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

    Colon, C.; Alonso-Medina, A.; Zanon, A.

    2008-10-22

    Oscillator strengths for several lines of astrophysical interest arising from some configurations and some levels radiative lifetimes of Pb IV have been calculated. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree-Fock calculations. We use for the IC calculations the standard method of least square fitting of experimental energy levels by means of computer codes from Cowan. Transition Probabilities and oscillator strengths obtained, although in general agreement with the rare experimental data, do present some noticeable discrepancies that are studied in the text.

  1. Oscillator Strengths and Predissociation Widths for Rydberg Transitions in Carbon Monoxide

    NASA Technical Reports Server (NTRS)

    Federman, Steven R.; Sheffer, Y.; Eidelsberg, Michele; Lemaire, Jean-Louis; Fillion, Jean-Hugues; Rostas, Francois; Ruiz, J.

    2006-01-01

    CO is used as a probe of astronomical environments ranging from planetary atmospheres and comets to interstellar clouds and the envelopes surrounding stars near the end of their lives. One of the processes controlling the CO abundance and the ratio of its isotopomers is photodissociation. Accurate oscillator strengths for Rydberg transitions are needed for modeling this process. Absorption bands were analyzed by synthesizing the profiles with codes developed independently in Meudon and Toledo. Each synthetic spectrum was adjusted to match the experimental one in a non-linear least-squares fitting procedure with the band oscillator strength, the line width (instrumental and predissociation.

  2. Core excitation effects on oscillator strengths for transitions in four electron atomic systems

    NASA Astrophysics Data System (ADS)

    Chang, T. N.; Luo, Yuxiang

    2007-06-01

    By including explicitly the electronic configurations with two and three simultaneously excited electronic orbital, we have extended the BSCI (B-spline based configuration interaction) method [1] to estimate directly the effect of inner shell core excitation to oscillator strengths for transitions in four-electron atomic systems. We will present explicitly the change in oscillator strengths due to core excitations, especially for transitions involving doubly excited states and those with very small oscillator strengths. The length and velocity results are typically in agreement better than 1% or less. [1] Tu-nan Chang, in Many-body Theory of Atomic Structure and Photoionization, edited by T. N. Chang (World Scientific, Singapore, 1993), p. 213-47; and T. N. Chang and T. K. Fang, Elsevier Radiation Physics and Chemistry 70, 173-190 (2004).

  3. Relationships between central arterial stiffness, lean body mass, and absolute and relative strength in young and older men and women.

    PubMed

    Fahs, Christopher A; Thiebaud, Robert S; Rossow, Lindy M; Loenneke, Jeremy P; Bemben, Debra A; Bemben, Michael G

    2017-08-16

    Relationships between muscular strength and arterial stiffness as well as between muscle mass and arterial stiffness have been observed suggesting a link between the neuromuscular system and vascular health. However, the relationship between central arterial stiffness and absolute and relative strength along with muscle mass has not been investigated in both sexes across a broad age range. The purpose of this study was to examine the relationship between central arterial stiffness and absolute and relative strength as well as between central arterial stiffness and lean body mass (LBM) in men and women across a broad age range. LBM, central arterial stiffness and strength were measured on 36 men and 35 women between the ages of 18 and 75 years. Strength was measured on five machine resistance exercises and summed as one measure of overall strength (absolute strength). Relative strength was calculated as total strength divided by LBM (relative strength). Central arterial stiffness was inversely related to both absolute (r = -0·230; P = 0·029) and relative strength (r = -0·484; P < 0·001) but not LBM (r = 0·097; P = 0·213). The relationship between central arterial stiffness and relative strength was attenuated but still present when controlling for either age, per cent body fat, LBM or mean arterial pressure. These results suggest that, across a wide age range, the expression of relative muscular strength has a stronger relationship with central arterial stiffness compared to either LBM or absolute strength. This suggests that muscle function more than muscle mass may be coupled with vascular health. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  4. Absolute differential cross sections for electron impact excitation of the 10.8-11.5 eV energy-loss states of CO2

    NASA Astrophysics Data System (ADS)

    Green, M. A.; Teubner, P. J. O.; Campbell, L.; Brunger, M. J.; Hoshino, M.; Ishikawa, T.; Kitajima, M.; Tanaka, H.; Itikawa, Y.; Kimura, M.; Buenker, R. J.

    2002-02-01

    Absolute differential cross sections (DCSs) for electron impact excitation of electronic states of CO2 in the 10.8-11.5 eV energy-loss range are reported. These data were obtained at the incident electron energies 20,30,60,100 and 200 eV and over the scattered electron angular range 3.5°-90°. The accuracy of our experimental methods has been established independently by using several different normalization techniques at both Sophia and Flinders Universities. Generalized oscillator strengths were derived from our measured DCSs and then extrapolated to zero momentum transfer, in order to determine the optical oscillator strengths. These optical oscillator strengths, where possible, are compared with the results from previous measurements and calculations.

  5. Determining the Strength of an Electromagnet through Damped Oscillations

    ERIC Educational Resources Information Center

    Thompson, Michael; Leung, Chi Fan

    2011-01-01

    This article describes a project designed to extend sixth-form pupils looking to further their knowledge and skill base in physics. This project involves a quantitative analysis of the decaying amplitude of a metal plate oscillating in a strong magnetic field; the decay of the amplitude is used to make estimates of the strength of the magnetic…

  6. Energy Levels and Oscillator Strengths for Allowed Transitions in S III

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    1995-01-01

    We have calculated energy levels and oscillator strengths for dipole-allowed transitions between the terms belonging to the 3s(sup 2)3p(sup 2), 3s3p(sup 3), 3S(sup 2)3p3d, 3S(sup 2)3p4s, 3S(sup 2)3p4p and 3s(sup 2)3p4d configurations of S iii in the LS-coupling scheme. We used flexible radial functions and included a large number of configurations in the configuration-interaction expansions to ensure convergence. The calculated energy levels are in close agreement with the recent laboratory measurement. The present oscillator strengths are compared with other calculations and experiments and most of the existing discrepancies between the available calculations are resolved.

  7. Energy levels, oscillator strengths, and transition probabilities for sulfur-like scandium, Sc VI

    NASA Astrophysics Data System (ADS)

    El-Maaref, A. A.; Abou Halaka, M. M.; Saddeek, Yasser B.

    2017-09-01

    Energy levels, Oscillator strengths, and transition probabilities for sulfur-like scandium are calculated using CIV3 code. The calculations have been executed in an intermediate coupling scheme using Breit-Pauli Hamiltonian. The present calculations have been compared with the experimental data and other theoretical calculations. LANL code has been used to confirm the accuracy of the present calculations, where the calculations using CIV3 code agree well with the corresponding values by LANL code. The calculated energy levels and oscillator strengths are in reasonable agreement with the published experimental data and theoretical values. We have calculated lifetimes of some excited levels, as well.

  8. Optical oscillator strength distribution of amino acids from 3 to 250 eV and examination of the Thomas Reiche Kuhn sum rule

    NASA Astrophysics Data System (ADS)

    Kamohara, Masumi; Izumi, Yudai; Tanaka, Masafumi; Okamoto, Keiko; Tanaka, Masahito; Kaneko, Fusae; Kodama, Yoko; Koketsu, Toshiyuki; Nakagawa, Kazumichi

    2008-10-01

    Absorption spectra of thin films of glycine (Gly), alanine (Ala), valine (Val), serine (Ser), leucine (Leu), phenylalanine (Phe) and methinine (Met) were measured in absolute values of absorption cross section σ( E) for the photon energy E from 3 to 250 eV. We translated σ( E) into the optical oscillator strength distribution df/dE and we examined the Thomas-Reiche-Kuhn sum rule [Hirschfelder, J.O., Curtiss, C.F., Bird, R.B., 1954. Molecular Theory of Gases and Liquids. Wiley, New York, p. 890]. We concluded that T-R-K sum rule was correctly applicable for such relatively large size of biomolecules.

  9. VizieR Online Data Catalog: Ba V, Ba VI, and Ba VII oscillator strengths (Rauch+, 2014)

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-04-01

    table1.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba V. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table2.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VI. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. table3.dat contains calculated HFR oscillator strengths (loggf) and transition probabilities (gA, in 1/s) in Ba VII. CF is the cancellation factor as defined by Cowan (1981). In columns 3 and 6, e is written for even and o for odd. (3 data files).

  10. Oscillator strengths of selected resonance transitions in neutral sulfur

    NASA Technical Reports Server (NTRS)

    Beideck, D. J.; Schectman, R. M.; Federman, S. R.; Ellis, D. G.

    1994-01-01

    Mean lives and branching ratios for the 4s (3)S(sup 0 sub 1) and 4s(double prime) (3)P(sup 0 sub 1, 2) levels of neutral sulfur were determined at the Toledo Heavy Ion Accelerator using beam-foil spectroscopic techniques. The mean lives obtained for the 4s (3)S(sup 0 sub 1) 4s(double prime) (3)P(sup 0 sub 1), and (3)P(sup 0 sub 2) levels, 1.875 +/- 0.094 ns, 2.034 +/- 0.102 ns, and 2.146 +/- 0.129 ns, respectively, represent the most accurate results available to date. Oscillator strengths for the transitions 3p(sup 4)(3)P(sub 2, 1, 0)-4s (3)S(sup 0 sub 1) and 3p(sup 4)(3)P(sub 2, 1, 0)-4s(double prime) (3)P(sup 0 sub 1, 2) were derived from these mean lives together with the measured branching ratios. For comparison with published results which present only multiplet f-values, such f-values were computed from the measured individual line oscillator strengths. The value obtained for the 3p(sup 4)(3)P-4s(sup 3)S(sup 0) multiplet at 1814 A is 0.088 +/- 0.005, in good agreement with the mean of previous experimental measurements and theoretical calculations. With the mean life for the 4s(double prime) 3P(sup 0 sub 0) level set equal to the mean of our determination for the other two 4s(double prime) (3)P(sup 0) levels (a valid assumption for LS coupling conditions, and consistent with the observed equality of the mean lives within the accuracy of our measurement), an oscillator strength for the 1299 A multiplet of 0.121 +/- 0.004 was found. Both results are in good agreement with recent large-scale theoretical calculations that incorporate the effects of configuration interaction.

  11. Laboratory oscillator strengths of Sc i in the near-infrared region for astrophysical applications

    NASA Astrophysics Data System (ADS)

    Pehlivan, A.; Nilsson, H.; Hartman, H.

    2015-10-01

    Context. Atomic data is crucial for astrophysical investigations. To understand the formation and evolution of stars, we need to analyse their observed spectra. Analysing a spectrum of a star requires information about the properties of atomic lines, such as wavelengths and oscillator strengths. However, atomic data of some elements are scarce, particularly in the infrared region, and this paper is part of an effort to improve the situation on near-IR atomic data. Aims: This paper investigates the spectrum of neutral scandium, Sc I, from laboratory measurements and improves the atomic data of Sc I lines in the infrared region covering lines in R, I, J, and K bands. Especially, we focus on measuring oscillator strengths for Sc I lines connecting the levels with 4p and 4s configurations. Methods: We combined experimental branching fractions with radiative lifetimes from the literature to derive oscillator strengths (f-values). Intensity-calibrated spectra with high spectral resolution were recorded with Fourier transform spectrometer from a hollow cathode discharge lamp. The spectra were used to derive accurate oscillator strengths and wavelengths for Sc I lines, with emphasis on the infrared region. Results: This project provides the first set of experimental Sc I lines in the near-infrared region for accurate spectral analysis of astronomical objects. We derived 63 log(gf) values for the lines between 5300 Å and 24 300 Å. The uncertainties in the f-values vary from 5% to 20%. The small uncertainties in our values allow for an increased accuracy in astrophysical abundance determinations.

  12. Use of an untuned cavity for absolute power measurements of the harmonics above 100 GHz from an IMPATT oscillator

    NASA Astrophysics Data System (ADS)

    Llewellyn-Jones, D. T.; Knight, R. J.; Gebbie, H. A.

    1980-07-01

    A new technique of measuring absolute power exploiting an untuned cavity and Fourier spectroscopy has been used to examine the power spectrum of the harmonics and other overtones produced by a 95 GHz IMPATT oscillator. The conditions which favor the production of a rich harmonic spectrum are not those which maximize the fundamental power. Under some conditions of mismatch at the fundamental frequency it is possible to produce over 200 microW of harmonic power in the 100-200 GHz region comparable with the fundamental power from the oscillator.

  13. Absolute Total Photoionization Cross Section of C60 in the Range of 25-120 eV: Revisited

    NASA Astrophysics Data System (ADS)

    Kafle, Bhim P.; Katayanagi, Hideki; Prodhan, Md. Serajul I.; Yagi, Hajime; Huang, Chaoqun; Mitsuke, Koichiro

    2008-01-01

    The absolute total photoionization cross section σabs,I of gaseous C60 is measured in the photon energy hν range from 25 to 120 eV by photoionization mass spectrometry with synchrotron radiation. The absolute detection efficiencies of photoions in different charge states are evaluated. The present σabs,I curve is combined with the photoabsorption cross section curves of C60 at hν=3.5--26 eV in the literature, after appropriate alterations of the vapor pressure are taken into account. The oscillator strengths are computed from the composite curve to be 178.5 and 230.5 for the hν ranges from 3.5 to 40.8 eV and from 3.5 to 119 eV, respectively. These oscillator strengths agree well with those expected from the Thomas-Kuhn-Reiche sum rule and 60 times the photoabsorption cross section of a carbon atom. Moreover, the present σabs,I curve behaves similarly to the relative photoionization cross section curve reported by Reinköster et al.

  14. Oscillator strengths and integral cross sections for the valence-shell excitations of nitric oxide studied by fast electron impact.

    PubMed

    Xu, Xin; Xu, Long-Quan; Xiong, Tao; Chen, Tao; Liu, Ya-Wei; Zhu, Lin-Fan

    2018-01-28

    The generalized oscillator strengths for the valence-shell excitations of A 2 Σ + , C 2 Π, and D 2 Σ + electronic-states of nitric oxide have been determined at an incident electron energy of 1500 eV with an energy resolution of 70 meV. The optical oscillator strengths for these transitions have been obtained by extrapolating the generalized oscillator strengths to the limit that the squared momentum transfer approaches to zero, which give an independent cross-check to the previous experimental and theoretical results. The integral cross sections for the valence-shell excitations of nitric oxide have been determined systematically from the threshold to 2500 eV with the aid of the newly developed BE-scaling method for the first time. The present optical oscillator strengths and integral cross sections of the valence-shell excitations of nitric oxide play an important role in understanding many physics and chemistry of the Earth's upper atmosphere such as the radiative cooling, ozone destruction, day glow, aurora, and so on.

  15. Plexcitons: The Role of Oscillator Strengths and Spectral Widths in Determining Strong Coupling.

    PubMed

    Thomas, Reshmi; Thomas, Anoop; Pullanchery, Saranya; Joseph, Linta; Somasundaran, Sanoop Mambully; Swathi, Rotti Srinivasamurthy; Gray, Stephen K; Thomas, K George

    2018-01-23

    Strong coupling interactions between plasmon and exciton-based excitations have been proposed to be useful in the design of optoelectronic systems. However, the role of various optical parameters dictating the plasmon-exciton (plexciton) interactions is less understood. Herein, we propose an inequality for achieving strong coupling between plasmons and excitons through appropriate variation of their oscillator strengths and spectral widths. These aspects are found to be consistent with experiments on two sets of free-standing plexcitonic systems obtained by (i) linking fluorescein isothiocyanate on Ag nanoparticles of varying sizes through silane coupling and (ii) electrostatic binding of cyanine dyes on polystyrenesulfonate-coated Au nanorods of varying aspect ratios. Being covalently linked on Ag nanoparticles, fluorescein isothiocyanate remains in monomeric state, and its high oscillator strength and narrow spectral width enable us to approach the strong coupling limit. In contrast, in the presence of polystyrenesulfonate, monomeric forms of cyanine dyes exist in equilibrium with their aggregates: Coupling is not observed for monomers and H-aggregates whose optical parameters are unfavorable. The large aggregation number, narrow spectral width, and extremely high oscillator strength of J-aggregates of cyanines permit effective delocalization of excitons along the linear assembly of chromophores, which in turn leads to efficient coupling with the plasmons. Further, the results obtained from experiments and theoretical models are jointly employed to describe the plexcitonic states, estimate the coupling strengths, and rationalize the dispersion curves. The experimental results and the theoretical analysis presented here portray a way forward to the rational design of plexcitonic systems attaining the strong coupling limits.

  16. Lifetime measurements and oscillator strengths in singly ionized scandium and the solar abundance of scandium

    NASA Astrophysics Data System (ADS)

    Pehlivan Rhodin, A.; Belmonte, M. T.; Engström, L.; Lundberg, H.; Nilsson, H.; Hartman, H.; Pickering, J. C.; Clear, C.; Quinet, P.; Fivet, V.; Palmeri, P.

    2017-12-01

    The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s and 4p2) in the region 57 743-77 837 cm-1 of singly ionized scandium (Sc II) were measured by two-step time-resolved laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer. In addition, Hartree-Fock calculations where both the main relativistic and core-polarization effects were taken into account were carried out for both low- and high-excitation levels. There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler & Dakin in the region 9000-45 000 cm-1 for low excitation levels and with our measurements for high excitation levels in the region 23 500-63 100 cm-1. This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in Sc II. These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium. The solar abundance of scandium is now estimated to logε⊙ = 3.04 ± 0.13 using these semi-empirical oscillator strengths to shift the values determined by Scott et al. The new estimated abundance value is in agreement with the meteoritic value (logεmet = 3.05 ± 0.02) of Lodders, Palme & Gail.

  17. Laboratory astrophysics under the ultraviolet, visible, and gravitational astrophysics research program: Oscillator strengths for ultraviolet atomic transitions

    NASA Technical Reports Server (NTRS)

    Federman, Steven R.

    1992-01-01

    The conditions within astrophysical environments can be derived from observational data on atomic and molecular lines. For instance, the density and temperature of the gas are obtained from relative populations among energy levels. Information on populations comes about only when the correspondence between line strength and abundance is well determined. The conversion from line strength to abundance involves knowledge of meanlives and oscillator strengths. For many ultraviolet atomic transitions, unfortunately, the necessary data are either relatively imprecise or not available. Because of the need for more and better atomic oscillator strengths, our program was initiated. Through beam-foil spectroscopy, meanlives of ultraviolet atomic transitions are studied. In this technique, a nearly isotopically pure ion beam of the desired element is accelerated. The beam passes through a thin carbon foil (2 mg/cu cm), where neutralization, ionization, and excitation take place. The dominant process depends on the energy of the beam. Upon exiting the foil, the decay of excited states is monitored via single-photon-counting techniques. The resulting decay curve yields a meanlife. The oscillator strength is easily obtained from the meanlife when no other decay channels are presented. When other channels are present, additional measurements or theoretical calculations are performed in order to extract an oscillator strength. During the past year, three atomic systems have been studied experimentally and/or theoretically; they are Ar, I, Cl I, and N II. The results for the first two are important for studies of interstellar space, while the work on N II bears on processes occurring in planetary atmospheres.

  18. Improved Wavelengths and Oscillator Strengths of Doubly Ionized Iron Group Elements

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Smillie, D. G.; Pickering, J. C.; Nave, G.; Blackwell-Whitehead, R. J.

    2007-05-01

    Improvements in the resolution, accuracy, and range of astrophysical spectra obtained by state-of-the-art space-and ground-based spectrographs have highlighted the need for corresponding improvements in the atomic data. Transition wavelengths with uncertainties of 1 part in 10^7 and oscillator strengths with uncertainties of 10 to 15% are needed to accurately interpret modern astrophysical spectra. The spectra of hot (B-type) stars are dominated by the doubly ionized spectra of the iron group elements. We present new measurements of Cr III, Fe III, and Co III made with a Fourier transform spectrometer (FTS) and a Penning discharge source. The FTS at Imperial College [J. C. Pickering, Vibrational Spectrosc., 29, pp.27-43 (2002)] covers a spectral range from the visible to the VUV (down to 140 nm) with a typical wavenumber uncertainty of a few parts in 10^8. Additional measurements were carried out at the US National Institute of Standards & Technology using their FTS and the Normal Incidence Vacuum (grating) Spectrograph (NIVS). The NIVS spectra were recorded beyond the FTS wavelength cut-off using phosphor image plates, which have the advantage over conventional photographic plates of a linear intensity response over a wide dynamic range, thus allowing branching ratios, and hence oscillator strengths, to be determined. Intensity- and wavelength-calibrated line lists have been produced, and term analyses are underway. Measured lines are, in many cases, an order of magnitude more accurate than previous measurements and the energy level uncertainty established is typically improved by a factor or 3 more. Work is also underway to establish new measured oscillator strengths for Fe III. This work is supported in part by NASA Grant NAG5-12,668, NASA inter-agency agreement W-10,255, PPARC, the Royal Society of the UK, and by the Leverhulme Trust.

  19. CC2 oscillator strengths within the local framework for calculating excitation energies (LoFEx).

    PubMed

    Baudin, Pablo; Kjærgaard, Thomas; Kristensen, Kasper

    2017-04-14

    In a recent work [P. Baudin and K. Kristensen, J. Chem. Phys. 144, 224106 (2016)], we introduced a local framework for calculating excitation energies (LoFEx), based on second-order approximated coupled cluster (CC2) linear-response theory. LoFEx is a black-box method in which a reduced excitation orbital space (XOS) is optimized to provide coupled cluster (CC) excitation energies at a reduced computational cost. In this article, we present an extension of the LoFEx algorithm to the calculation of CC2 oscillator strengths. Two different strategies are suggested, in which the size of the XOS is determined based on the excitation energy or the oscillator strength of the targeted transitions. The two strategies are applied to a set of medium-sized organic molecules in order to assess both the accuracy and the computational cost of the methods. The results show that CC2 excitation energies and oscillator strengths can be calculated at a reduced computational cost, provided that the targeted transitions are local compared to the size of the molecule. To illustrate the potential of LoFEx for large molecules, both strategies have been successfully applied to the lowest transition of the bivalirudin molecule (4255 basis functions) and compared with time-dependent density functional theory.

  20. Constrained dipole oscillator strength distributions, sum rules, and dispersion coefficients for Br2 and BrCN

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Thakkar, Ajit J.

    2017-03-01

    Dipole oscillator strength distributions for Br2 and BrCN are constructed from photoabsorption cross-sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule, the high-energy behavior of the dipole-oscillator-strength density and molar refractivity data when available. The distributions are used to predict dipole sum rules S (k) , mean excitation energies I (k) , and van der Waals C6 coefficients. Coupled-cluster calculations of the static dipole polarizabilities of Br2 and BrCN are reported for comparison with the values of S (- 2) extracted from the distributions.

  1. Oscillator strengths and branching fractions of 4d75p-4d75s Rh II transitions

    NASA Astrophysics Data System (ADS)

    Bouazza, Safa

    2017-01-01

    This work reports semi-empirical determination of oscillator strengths, transition probabilities and branching fractions for Rh II 4d75p-4d75s transitions in a wide wavelength range. The angular coefficients of the transition matrix, beforehand obtained in pure SL coupling with help of Racah algebra are transformed into intermediate coupling using eigenvector amplitudes of these two configuration levels determined for this purpose; The transition integral was treated as free parameter in the least squares fit to experimental oscillator strength (gf) values found in literature. The extracted value: <4d75s|r1|4d75p> =2.7426 ± 0.0007 is slightly smaller than that computed by means of ab-initio method. Subsequently to oscillator strength evaluations, transition probabilities and branching fractions were deduced and compared to those obtained experimentally or through another approach like pseudo-relativistic Hartree-Fock model including core-polarization effects.

  2. The consequences of improperly describing oscillator strengths beyond the electric dipole approximation.

    PubMed

    Lestrange, Patrick J; Egidi, Franco; Li, Xiaosong

    2015-12-21

    The interaction between a quantum mechanical system and plane wave light is usually modeled within the electric dipole approximation. This assumes that the intensity of the incident field is constant over the length of the system and transition probabilities are described in terms of the electric dipole transition moment. For short wavelength spectroscopies, such as X-ray absorption, the electric dipole approximation often breaks down. Higher order multipoles are then included to describe transition probabilities. The square of the magnetic dipole and electric quadrupole are often included, but this results in an origin-dependent expression for the oscillator strength. The oscillator strength can be made origin-independent if all terms through the same order in the wave vector are retained. We will show the consequences and potential pitfalls of using either of these two expressions. It is shown that the origin-dependent expression may violate the Thomas-Reiche-Kuhn sum rule and the origin-independent expression can result in negative transition probabilities.

  3. The consequences of improperly describing oscillator strengths beyond the electric dipole approximation

    NASA Astrophysics Data System (ADS)

    Lestrange, Patrick J.; Egidi, Franco; Li, Xiaosong

    2015-12-01

    The interaction between a quantum mechanical system and plane wave light is usually modeled within the electric dipole approximation. This assumes that the intensity of the incident field is constant over the length of the system and transition probabilities are described in terms of the electric dipole transition moment. For short wavelength spectroscopies, such as X-ray absorption, the electric dipole approximation often breaks down. Higher order multipoles are then included to describe transition probabilities. The square of the magnetic dipole and electric quadrupole are often included, but this results in an origin-dependent expression for the oscillator strength. The oscillator strength can be made origin-independent if all terms through the same order in the wave vector are retained. We will show the consequences and potential pitfalls of using either of these two expressions. It is shown that the origin-dependent expression may violate the Thomas-Reiche-Kuhn sum rule and the origin-independent expression can result in negative transition probabilities.

  4. Sensation seeking, augmenting-reducing, and absolute auditory threshold: a strength-of-the-nervous-system perspective.

    PubMed

    Goldman, D; Kohn, P M; Hunt, R W

    1983-08-01

    The following measures were obtained from 42 student volunteers: the General and the Disinhibition subscales of the Sensation Seeking Scale (Form IV), the Reducer-Augmenter Scale, and the Absolute Auditory Threshold. General sensation seeking correlated significantly with the Reducer-Augmenter Scale, r(40) = .59, p less than .001, and the Absolute Auditory Threshold, r(40) = .45, p less than .005. Both results proved general across sex. These findings, that high-sensation seekers tend to be reducers and to lack sensitivity to weak stimulation, were interpreted as supporting strength-of-the-nervous-system theory more than the formulation of Zuckerman and his associates.

  5. Precise measurement of coupling strength and high temperature quantum effect in a nonlinearly coupled qubit-oscillator system

    NASA Astrophysics Data System (ADS)

    Ge, Li; Zhao, Nan

    2018-04-01

    We study the coherence dynamics of a qubit coupled to a harmonic oscillator with both linear and quadratic interactions. As long as the linear coupling strength is much smaller than the oscillator frequency, the long time behavior of the coherence is dominated by the quadratic coupling strength g 2. The coherence decays and revives at a period , with the width of coherence peak decreasing as the temperature increases, hence providing a way to measure g 2 precisely without cooling. Unlike the case of linear coupling, here the coherence dynamics never reduces to the classical limit in which the oscillator is classical. Finally, the validity of linear coupling approximation is discussed and the coherence under Hahn-echo is evaluated.

  6. Accurate oscillator strengths for ultraviolet lines of Ar I - Implications for interstellar material

    NASA Technical Reports Server (NTRS)

    Federman, S. R.; Beideck, D. J.; Schectman, R. M.; York, D. G.

    1992-01-01

    Analysis of absorption from interstellar Ar I in lightly reddened lines of sight provides information on the warm and hot components of the interstellar medium near the sun. The details of the analysis are limited by the quality of the atomic data. Accurate oscillator strengths for the Ar I lines at 1048 and 1067 A and the astrophysical implications are presented. From lifetimes measured with beam-foil spectroscopy, an f-value for 1048 A of 0.257 +/- 0.013 is obtained. Through the use of a semiempirical formalism for treating singlet-triplet mixing, an oscillator strength of 0.064 +/- 0.003 is derived for 1067 A. Because of the accuracy of the results, the conclusions of York and colleagues from spectra taken with the Copernicus satellite are strengthened. In particular, for interstellar gas in the solar neighborhood, argon has a solar abundance, and the warm, neutral material is not pervasive.

  7. Accurate Calculation of Oscillator Strengths for CI II Lines Using Non-orthogonal Wavefunctions

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    2004-01-01

    Non-orthogonal orbitals technique in the multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities for allowed and intercombination lines in Cl II. The relativistic corrections are included through the Breit-Pauli Hamiltonian. The Cl II wave functions show strong term dependence. The non-orthogonal orbitals are used to describe the term dependence of radial functions. Large sets of spectroscopic and correlation functions are chosen to describe adequately strong interactions in the 3s(sup 2)3p(sup 3)nl (sup 3)Po, (sup 1)Po and (sup 3)Do Rydberg series and to properly account for the important correlation and relaxation effects. The length and velocity forms of oscillator strength show good agreement for most transitions. The calculated radiative lifetime for the 3s3p(sup 5) (sup 3)Po state is in good agreement with experiment.

  8. Revisiting an old concept: the coupled oscillator model for VCD. Part 1: the generalised coupled oscillator mechanism and its intrinsic connection to the strength of VCD signals.

    PubMed

    Nicu, Valentin Paul

    2016-08-03

    Motivated by the renewed interest in the coupled oscillator (CO) model for VCD, in this work a generalised coupled oscillator (GCO) expression is derived by introducing the concept of a coupled oscillator origin. Unlike the standard CO expression, the GCO expression is exact within the harmonic approximation. Using two illustrative example molecules, the theoretical concepts introduced here are demonstrated by performing a GCO decomposition of the rotational strengths computed using DFT. This analysis shows that: (1) the contributions to the rotational strengths that are normally neglected in the standard CO model can be comparable to or larger than the CO contribution, and (2) the GCO mechanism introduced here can affect the VCD intensities of all types of modes in symmetric and asymmetric molecules.

  9. Image Charge and Electric Field Effects on Hydrogen-like Impurity-bound Polaron Energies and Oscillator Strengths in a Quantum Dot

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    By using Landau-Pekar variational method, the ground and the first excited state energies and the transition frequencies between the ground and the first excited states of a hydrogen-like impurity-bound polaron in a spherical quantum dot (QD) have been studied by taking into account the image charge effect (ICE). We employ the dielectric continuum model to describe the phonon confinement effects. The oscillator strengths (OSs) of transitions from the 1 s-like state to excited states of 2 s, 2 p x , and 2 p z symmetries are calculated as functions of the applied electric field and strength of the confinement potential. We have shown that with and without image charge effect, the increase of the strength of the parabolic confinement potential leads to the increase of the oscillator strengths of 1 s - 2 p x and 1 s - 2 p z transitions. This indicates that the energy differences between 1 s- and 2 p x - as well as 1 s- and 2 p z -like states have a dominant role determining the oscillator strength. Although there is almost no difference in the oscillator strengths for transitions 1 s - 2 p x and 1 s -2 p z when the image charge effect is not taken into account, it becomes significant with the image charge effect.

  10. PREFACE: Atomic Spectra and Oscillator Strengths (ASOS9) Atomic Spectra and Oscillator Strengths (ASOS9)

    NASA Astrophysics Data System (ADS)

    Wahlgren, Glenn M.; Wiese, Wolfgang L.; Beiersdorfer, Peter

    2009-05-01

    For the first time since its inaugural meeting in Lund in 1983, the triennial international conference on Atomic Spectroscopy and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS) returned to Lund, Sweden. Lund has been a home to atomic spectroscopy since the time of Janne Rydberg, and included the pioneering work in laboratory and solar spectroscopy by Bengt Edlén, who presented the initial ASOS talk in 1983. The ninth ASOS was hosted by the Lund Observatory and Physics Department of Lund University, 7-10 August 2007, and was attended by 99 registrants. An encouraging sign for the field was the number of young researchers in attendance. This volume of Physica Scripta contains contributions from the invited presentations of the conference. For the first time, papers from the ASOS9 poster presentations have been made feely available online in a complementary volume of Journal of Physics: Conference Series. With these two volumes the character of ASOS9 is more evident, and together they serve as a review of the state of atomic spectroscopy for spectrum analysis and the determination of oscillator strengths and their applications. The goal of ASOS is to be a forum for atomic spectroscopy, where both the providers and the users of atomic data, which includes wavelengths, energy levels, lifetimes, oscillator strengths and line shape parameters, can meet to discuss recent advances in experimental and theoretical techniques and their application to understanding the physical processes that are responsible for producing observed spectra. The applications mainly originate from the fields of astrophysics and plasma physics, which includes fusion energy and lighting research. The oral presentations, all but one of which are presented in this volume, provided an extensive synopsis of techniques currently in use and those that are being planned. New to ASOS9 was the extent to which techniques such as cold, trapped atoms and molecules and frequency combs are

  11. Minima in generalized oscillator strengths for initially excited hydrogen-like atoms

    NASA Technical Reports Server (NTRS)

    Matsuzawa, M.; Omidvar, K.; Inokuti, M.

    1976-01-01

    Generalized oscillator strengths for transitions from an initially excited state of a hydrogenic atom to final states (either discrete or continuum) have complicated structures, including minima and shoulders, as functions of the momentum transfer. Extensive calculations carried out in the present work have revealed certain systematics of these structures. Some implications of the minima to the energy dependence of the inner-shell ionization cross section of heavy atoms by proton impact are discussed.

  12. Control of Oscillation Patterns in a Symmetric Coupled Biological Oscillator System

    NASA Astrophysics Data System (ADS)

    Takamatsu, Atsuko; Tanaka, Reiko; Yamamoto, Takatoki; Fujii, Teruo

    2003-08-01

    A chain of three-oscillator system was constructed with living biological oscillators of phasmodial slime mold, Physarum polycehalum and the oscillation patterns were analyzed by the symmetric Hopf bifurcation theory using group theory. Multi-stability of oscillation patterns was observed, even when the coupling strength was fixed. This suggests that the coupling strength is not an effective parameter to obtain a desired oscillation pattern among the multiple patterns. Here we propose a method to control oscillation patterns using resonance to external stimulus and demonstrate pattern switching induced by frequency resonance given to only one of oscillators in the system.

  13. Energy Levels and Oscillator Strengths for Ne-like Iron Ions

    NASA Astrophysics Data System (ADS)

    Zhong, J. Y.; Zhang, J.; Zhao, G.; Lu, X..

    2004-02-01

    Energy levels and oscillator strengths among the 27 fine-structure levels belonging to the (1s22s2)2p6, 2p53s, 2p53p and 2p53d configurations of neon-like iron ion have been calculated by using three atomic structure codes, RCN/RCG, AUTOSTRUCTURE (AS) and GRASP. The relativistic corrections of the wave functions are taken into account in RCN/RCG calculations. The results well agree with experimental and theoretical data wherever available. Finally the accuracy of three codes was analyzed.

  14. Refractive index effects on the oscillator strength and radiative decay rate of 2,3-diazabicyclo[2.2.2]oct-2-ene.

    PubMed

    Mohanty, Jyotirmayee; Nau, Werner M

    2004-01-01

    The photophysical properties of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) were determined in 15 solvents, two supramolecular hosts (cucurbit[7]uril and beta-cyclodextrin) as well as in the gas phase. The oscillator strength and radiative decay rate of DBO as a function of refractive index i.e. polarizability have been analyzed. The oscillator strength increases by a factor of 10 upon going from the gas phase to the most polarizable carbon disulfide, while the corresponding radiative decay rates increase by a factor of 40. There is a good empirical correlation between the oscillator strength of the weakly allowed n,pi* transition of DBO and the reciprocal bulk polarizability, which can be employed to assess the polarizability of unknown microheterogeneous environments. A satisfactory correlation between the radiative decay rate and the square of the refractive index is also found, as previously documented for chromophores with allowed transitions. However, the correlation improves significantly when the oscillator strength is included in the correlation, which demonstrates the importance of this factor in the Strickler-Berg equation for chromophores with forbidden or weakly allowed transitions, for which the oscillator strength may be strongly solvent dependent. The radiative decay rate of DBO in two supramolecular assemblies has been determined, confirming the very low polarizability inside the cucurbituril cavity, in between perfluorohexane and the gas phase. The fluorescence quantum yield of DBO in the gas phase has been remeasured (5.1 +/- 0.5%) and was found to fall one full order of magnitude below a previously reported value.

  15. Accurate oscillator strengths for interstellar ultraviolet lines of Cl I

    NASA Technical Reports Server (NTRS)

    Schectman, R. M.; Federman, S. R.; Beideck, D. J.; Ellis, D. J.

    1993-01-01

    Analyses on the abundance of interstellar chlorine rely on accurate oscillator strengths for ultraviolet transitions. Beam-foil spectroscopy was used to obtain f-values for the astrophysically important lines of Cl I at 1088, 1097, and 1347 A. In addition, the line at 1363 A was studied. Our f-values for 1088, 1097 A represent the first laboratory measurements for these lines; the values are f(1088)=0.081 +/- 0.007 (1 sigma) and f(1097) = 0.0088 +/- 0.0013 (1 sigma). These results resolve the issue regarding the relative strengths for 1088, 1097 A in favor of those suggested by astronomical measurements. For the other lines, our results of f(1347) = 0.153 +/- 0.011 (1 sigma) and f(1363) = 0.055 +/- 0.004 (1 sigma) are the most precisely measured values available. The f-values are somewhat greater than previous experimental and theoretical determinations.

  16. On synchronization in power-grids modelled as networks of second-order Kuramoto oscillators

    NASA Astrophysics Data System (ADS)

    Grzybowski, J. M. V.; Macau, E. E. N.; Yoneyama, T.

    2016-11-01

    This work concerns analytical results on the role of coupling strength in the phenomenon of onset of complete frequency locking in power-grids modelled as a network of second-order Kuramoto oscillators. Those results allow estimation of the coupling strength for the onset of complete frequency locking and to assess the features of network and oscillators that favor synchronization. The analytical results are evaluated using an order parameter defined as the normalized sum of absolute values of phase deviations of the oscillators over time. The investigation of the frequency synchronization within the subsets of the parameter space involved in the synchronization problem is also carried out. It is shown that the analytical results are in good agreement with those observed in the numerical simulations. In order to illustrate the methodology, a case study is presented, involving the Brazilian high-voltage transmission system under a load peak condition to study the effect of load on the syncronizability of the grid. The results show that both the load and the centralized generation might have concurred to the 2014 blackout.

  17. Theoretical transition probabilities, oscillator strengths, and radiative lifetimes of levels in Pb IV

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

    Alonso-Medina, A.; Colon, C., E-mail: cristobal.colon@upm.e; Porcher, P.

    2011-01-15

    Transition probabilities and oscillator strengths of 176 spectral lines with astrophysical interest arising from 5d{sup 10}ns (n = 7,8), 5d{sup 10}np (n = 6,7), 5d{sup 10}nd (n = 6,7), 5d{sup 10}5f, 5d{sup 10}5g, 5d{sup 10}nh (n = 6,7,8), 5d{sup 9}6s{sup 2}, and 5d{sup 9}6s6p configurations, and radiative lifetimes for 43 levels of Pb IV, have been calculated. These values were obtained in intermediate coupling (IC) and using relativistic Hartree-Fock calculations including core-polarization effects. For the IC calculations, we use the standard method of least-square fitting from experimental energy levels by means of the Cowan computer code. The inclusion in thesemore » calculations of the 5d{sup 10}7p and 5d{sup 10}5f configurations has facilitated a complete assignment of the energy levels in the Pb IV. Transition probabilities, oscillator strengths, and radiative lifetimes obtained are generally in good agreement with the experimental data.« less

  18. Pseudospectral calculation of helium wave functions, expectation values, and oscillator strength

    NASA Astrophysics Data System (ADS)

    Grabowski, Paul E.; Chernoff, David F.

    2011-10-01

    We show that the pseudospectral method is a powerful tool for finding precise solutions of Schrödinger’s equation for two-electron atoms with general angular momentum. Realizing the method’s full promise for atomic calculations requires special handling of singularities due to two-particle Coulomb interactions. We give a prescription for choosing coordinates and subdomains whose efficacy we illustrate by solving several challenging problems. One test centers on the determination of the nonrelativistic electric dipole oscillator strength for the helium 11S→21P transition. The result achieved, 0.27616499(27), is comparable to the best in the literature. The formally equivalent length, velocity, and acceleration expressions for the oscillator strength all yield roughly the same accuracy. We also calculate a diverse set of helium ground-state expectation values, reaching near state-of-the-art accuracy without the necessity of implementing any special-purpose numerics. These successes imply that general matrix elements are directly and reliably calculable with pseudospectral methods. A striking result is that all the relevant quantities tested in this paper—energy eigenvalues, S-state expectation values and a bound-bound dipole transition between the lowest energy S and P states—converge exponentially with increasing resolution and at roughly the same rate. Each individual calculation samples and weights the configuration space wave function uniquely but all behave in a qualitatively similar manner. These results suggest that the method has great promise for similarly accurate treatment of few-particle systems.

  19. Ozone: Unresolved discrepancies for dipole oscillator strength distributions, dipole sums, and van der Waals coefficients

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Thakkar, Ajit J.

    2011-08-01

    Dipole oscillator strength distributions (DOSDs) for ozone are constructed from experimental photoabsorption cross-sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule, the high-energy behavior of the dipole-oscillator-strength density, and molar refractivity data. A lack of photoabsorption data in the intermediate energy region from 24 to 524 eV necessitates the use of a mixture rule in that region. For this purpose, a DOSD for O2 is constructed first. The dipole properties for O2 are essentially the same as those obtained in earlier work even though most of the input data is from more recent experiments. A discrepancy is found between the refractivity data and photoabsorption data in the 10-20.6 eV range for ozone. A reliable ozone DOSD of the sort obtained for many other species remains out of reach. However, it is suggested that the true dipole properties of ozone lie between those predicted by two distributions that we present.

  20. Oscillator strengths of the Si II 181 nanometer resonance multiplet

    NASA Technical Reports Server (NTRS)

    Bergeson, S. D.; Lawler, J. E.

    1993-01-01

    We report Si II experimental log (gf)-values of -2.38(4) for the 180.801 nm line, of -2.18(4) for the 181.693 nm line, and of -3.29(5) for the 181.745 nm line, where the number in parentheses is the uncertainty in the last digit. The overall uncertainties (about 10 percent) include the 1 sigma random uncertainty (about 6 percent) and an estimate of the systematic uncertainty. The oscillator strengths are determined by combining branching fractions and radiative lifetimes. The branching fractions are measured using standard spectroradiometry on an optically thin source; the radiative lifetimes are measured using time-resolved laser-induced fluorescence.

  1. Oscillator Strengths of Allowed and Intercombination Transitions in Neutral Sulfur

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    1998-01-01

    We have calculated oscillator strengths and transition probabilities of electric-dipole allowed and intercombination transitions from fine-structure levels of the ground 3s(sup 2)3p(sup 4) configuration to the levels belonging to configurations 3s(sup 2)3p(sup 3)4s, 3s(sup 2) 3p(sup 3)5s, 3(sup 2)3p(sup 3)3d, 3s(sup 2)3p(sup 3)4d of neutral sulfur. Extensive configuration-interaction wave functions are used to represent these levels. The relativistic corrections have been included through the Breit-Pauli Hamiltonian. The results are compared with previous theoretical calculations and with measurements.

  2. Hydrodynamic Characteristics and Strength Analysis of a Novel Dot-matrix Oscillating Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Shao, Meng; Xiao, Chengsi; Sun, Jinwei; Shao, Zhuxiao; Zheng, Qiuhong

    2017-12-01

    The paper analyzes hydrodynamic characteristics and the strength of a novel dot-matrix oscillating wave energy converter, which is in accordance with nowadays’ research tendency: high power, high efficiency, high reliability and low cost. Based on three-dimensional potential flow theory, the paper establishes motion control equations of the wave energy converter unit and calculates wave loads and motions. On this basis, a three-dimensional finite element model of the device is built to check its strength. Through the analysis, it can be confirmed that the WEC is feasible and the research results could be a reference for wave energy’s exploration and utilization.

  3. The consequences of improperly describing oscillator strengths beyond the electric dipole approximation

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

    Lestrange, Patrick J.; Egidi, Franco; Li, Xiaosong, E-mail: xsli@uw.edu

    2015-12-21

    The interaction between a quantum mechanical system and plane wave light is usually modeled within the electric dipole approximation. This assumes that the intensity of the incident field is constant over the length of the system and transition probabilities are described in terms of the electric dipole transition moment. For short wavelength spectroscopies, such as X-ray absorption, the electric dipole approximation often breaks down. Higher order multipoles are then included to describe transition probabilities. The square of the magnetic dipole and electric quadrupole are often included, but this results in an origin-dependent expression for the oscillator strength. The oscillator strengthmore » can be made origin-independent if all terms through the same order in the wave vector are retained. We will show the consequences and potential pitfalls of using either of these two expressions. It is shown that the origin-dependent expression may violate the Thomas-Reiche-Kuhn sum rule and the origin-independent expression can result in negative transition probabilities.« less

  4. A new Morse-oscillator based Hamiltonian for H 3+: Calculation of line strengths

    NASA Astrophysics Data System (ADS)

    Jensen, Per; Špirko, V.

    1986-07-01

    In two recent publications [V. Špirko, P. Jensen, P. R. Bunker, and A. Čejchan, J. Mol. Spectrosc.112, 183-202 (1985); P. Jensen, V. Špirko, and P. R. Bunker, J. Mol. Spectrosc.115, 269-293 (1986)], we have described the development of Morse oscillator adapted rotation-vibration Hamiltonians for equilateral triangular X3 and Y2X molecules, and we have used these Hamiltonians to calculate the rotation-vibration energies for H 3+ and its X3+ and Y2X+ isotopes from ab initio potential energy functions. The present paper presents a method for calculating rotation-vibration line strengths of H 3+ and its isotopes using an ab initio dipole moment function [G. D. Carney and R. N. Porter, J. Chem. Phys.60, 4251-4264 (1974)] together with the energies and wave-functions obtained by diagonalization of the Morse oscillator adapted Hamiltonians. We use this method for calculating the vibrational transition moments involving the lowest vibrational states of H 3+, D 3+, H 2D +, and D 2H +. Further, we calculate the line strengths of the low- J transitions in the rotational spectra of H 3+ in the vibrational ground state and in the ν1 and ν2 states. We hope that the calculations presented will facilitate the search for further rotation-vibration transitions of H 3+ and its isotopes.

  5. Rational Improvement of Molar Absorptivity Guided by Oscillator Strength: A Case Study with Furoindolizine-Based Core Skeleton.

    PubMed

    Lee, Youngjun; Jo, Ala; Park, Seung Bum

    2015-12-21

    The rational improvement of photophysical properties can be highly valuable for the discovery of novel organic fluorophores. Using our new design strategy guided by the oscillator strength, we developed a series of full-color-tunable furoindolizine analogs with improved molar absorptivity through the fusion of a furan ring into the indolizine-based Seoul fluorophore. The excellent correlation between the computable values (oscillator strength and theoretical S0 -S1 energy gap) and photophysical properties (molar absorptivity and emission wavelength) confirmed the effectualness of our design strategy. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

  6. Experimental radiative lifetimes, branching fractions, and oscillator strengths of some levels in Tm III

    NASA Astrophysics Data System (ADS)

    Yu, Qi; Wang, Xinghao; Li, Qiu; Gong, Yimin; Dai, Zhenwen

    2018-06-01

    Natural radiative lifetimes for five even-parity levels of Tm III were measured by time-resolved laser-induced fluorescence method. The branching fraction measurements were performed based on the emission spectra of a hollow cathode lamp. By combining the measured branching fractions and the lifetime values reported in this work and in literature, experimental transition probabilities and oscillator strengths for 11 transitions were derived for the first time.

  7. Derived properties from the dipole and generalized oscillator strength distributions of an endohedral confined hydrogen atom

    NASA Astrophysics Data System (ADS)

    Martínez-Flores, C.; Cabrera-Trujillo, R.

    2018-03-01

    We report the electronic properties of a hydrogen atom confined by a fullerene molecule by obtaining the eigenvalues and eigenfunctions of the time-independent Schrödinger equation by means of a finite-differences approach. The hydrogen atom confinement by a C60 fullerene cavity is accounted for by two model potentials: a square-well and a Woods-Saxon. The Woods-Saxon potential is implemented to study the role of a smooth cavity on the hydrogen atom generalized oscillator strength distribution. Both models characterize the cavity by an inner radius R 0, thickness Δ, and well depth V 0. We use two different values for R 0 and Δ, found in the literature, that characterize H@C60 to analyze the role of the fullerene cage size and width. The electronic properties of the confined hydrogen atom are reported as a function of the well depth V 0, emulating different electronic configurations of the endohedral cavity. We report results for the hyper-fine splitting, nuclear magnetic screening, dipole oscillator strength, the static and dynamic polarizability, mean excitation energy, photo-ionization, and stopping cross section for the confined hydrogen atom. We find that there is a critical potential well depth value around V 0 = 0.7 a.u. for the first set of parameters and around V 0 = 0.9 a.u. for the second set of parameters, which produce a drastic change in the electronic properties of the endohedral hydrogen system. These values correspond to the first avoided crossing on the energy levels. Furthermore, a clear discrepancy is found between the square-well and Woods-Saxon model potential results on the hydrogen atom generalized oscillator strength due to the square-well discontinuity. These differences are reflected in the stopping cross section for protons colliding with H@C60.

  8. Radiative lifetimes, branching fractions, and oscillator strengths of some levels in Be I

    NASA Astrophysics Data System (ADS)

    Wang, Xinghao; Quinet, Pascal; Li, Qiu; Yu, Qi; Li, Yongfan; Wang, Qian; Gong, Yimin; Dai, Zhenwen

    2018-06-01

    Radiative lifetimes of five levels in Be I lying in the energy range 64,506.45-71,160.52 cm-1 were measured by the time-resolved laser-induced fluorescence technique. These new data, together with previously measured radiative lifetimes and two reliable calculated lifetimes, were combined with branching fractions obtained from pseudo-relativistic Hartree-Fock calculations to deduce semi-empirical transition probabilities and oscillator strengths for 90 Be I spectral lines involving upper levels ranging from 42,565.35 to 72,251.27 cm-1.

  9. Transition from amplitude to oscillation death in a network of oscillators

    NASA Astrophysics Data System (ADS)

    Nandan, Mauparna; Hens, C. R.; Pal, Pinaki; Dana, Syamal K.

    2014-12-01

    We report a transition from a homogeneous steady state (HSS) to inhomogeneous steady states (IHSSs) in a network of globally coupled identical oscillators. We perturb a synchronized population of oscillators in the network with a few local negative or repulsive mean field links. The whole population splits into two clusters for a certain number of repulsive mean field links and a range of coupling strength. For further increase of the strength of interaction, these clusters collapse into a HSS followed by a transition to IHSSs where all the oscillators populate either of the two stable steady states. We analytically determine the origin of HSS and its transition to IHSS in relation to the number of repulsive mean-field links and the strength of interaction using a reductionism approach to the model network. We verify the results with numerical examples of the paradigmatic Landau-Stuart limit cycle system and the chaotic Rössler oscillator as dynamical nodes. During the transition from HSS to IHSSs, the network follows the Turing type symmetry breaking pitchfork or transcritical bifurcation depending upon the system dynamics.

  10. Cessation of oscillations in a chemo-mechanical oscillator

    NASA Astrophysics Data System (ADS)

    Phogat, Richa; Tiwari, Ishant; Kumar, Pawan; Rivera, Marco; Parmananda, Punit

    2018-06-01

    In this paper, different methods for cessation of oscillations in a chemo-mechanical oscillator [mercury beating heart (MBH)] are presented. The first set of experiments were carried out on a single MBH oscillator. To achieve cessation of oscillations, two protocols, namely, inverted feedback and delayed feedback were employed. In the second set of experiments, two quasi-identical MBH oscillators are considered. They are first synchronized via a bidirectional attractive coupling. These two synchronized oscillators are thereafter coupled with a unidirectional repulsive coupling and the system dynamics were observed. Subsequently, in the next protocol, the effect of a unidirectional delay coupling on the two synchronized oscillators was explored. The cessation of oscillations in all the above experimental setups was observed as the feedback/coupling was switched on at a suitable strength. Oscillatory dynamics of the system were restored when the feedback/coupling was switched off.

  11. Tradeoffs between oscillator strength and lifetime in terahertz quantum cascade lasers

    DOE PAGES

    Chan, Chun Wang I.; Albo, Asaf; Hu, Qing; ...

    2016-11-14

    Contemporary research into diagonal active region terahertz quantum cascade lasers for high temperature operation has yielded little success. We present evidence that the failure of high diagonality alone as a design strategy is due to a fundamental trade-off between large optical oscillator strength and long upper-level lifetime. Here, we hypothesize that diagonality needs to be paired with increased doping in order to succeed, and present evidence that highly diagonal designs can benefit from much higher doping than normally found in terahertz quantum cascade lasers. In assuming the benefits of high diagonality paired with high doping, we also highlight important challengesmore » that need to be overcome, specifically the increased importance of carrier induced band-bending and impurity scattering.« less

  12. Quadratic Zeeman effect in hydrogen Rydberg states: Rigorous error estimates for energy eigenvalues, energy eigenfunctions, and oscillator strengths

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

    Falsaperla, P.; Fonte, G.

    1994-10-01

    A variational method, based on some results due to T. Kato [Proc. Phys. Soc. Jpn. 4, 334 (1949)], and previously discussed is here applied to the hydrogen atom in uniform magnetic fields of tesla in order to calculate, with a rigorous error estimate, energy eigenvalues, energy eigenfunctions, and oscillator strengths relative to Rydberg states up to just below the field-free ionization threshold. Making use of a basis (parabolic Sturmian basis) with a size varying from 990 up to 5050, we obtain, over the energy range of [minus]190 to [minus]24 cm[sup [minus]1], all of the eigenvalues and a good part ofmore » the oscillator strengths with a remarkable accuracy. This, however, decreases with increasing excitation energy and, thus, above [similar to][minus]24 cm[sup [minus]1], we obtain results of good accuracy only for eigenvalues ranging up to [similar to][minus]12 cm[sup [minus]1].« less

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

    Klemt, M.

    Relative oscillator strengths of 139 Til lines were determined from emission measurements of a three chamber electric arc burning in an argon atmosphere. Introducing a small admixture of titanium chloride into the center of the arc, spectra of titanium could be observed end-on with no self-absorption and no selfreversal of the measured lines. The relative oscillator strengths were obtained from the Til line intensities and the measured arc temperature. Using absolute oscillator strengths of three resonance lines which had been measured by Reinke (1967), and several life time measurements from Hese (1970), Witt et al. (1971) and Andersen and Sorensenmore » (1972), the relative oscillator strengths were converted to an absolute scale. The accuracy of these absolute values is in the range of 20% to 40%. (auth)« less

  14. Transition from amplitude to oscillation death in a network of oscillators

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

    Nandan, Mauparna; Department of Mathematics, National Institute of Technology, Durgapur 713209; Hens, C. R.

    2014-12-01

    We report a transition from a homogeneous steady state (HSS) to inhomogeneous steady states (IHSSs) in a network of globally coupled identical oscillators. We perturb a synchronized population of oscillators in the network with a few local negative or repulsive mean field links. The whole population splits into two clusters for a certain number of repulsive mean field links and a range of coupling strength. For further increase of the strength of interaction, these clusters collapse into a HSS followed by a transition to IHSSs where all the oscillators populate either of the two stable steady states. We analytically determinemore » the origin of HSS and its transition to IHSS in relation to the number of repulsive mean-field links and the strength of interaction using a reductionism approach to the model network. We verify the results with numerical examples of the paradigmatic Landau-Stuart limit cycle system and the chaotic Rössler oscillator as dynamical nodes. During the transition from HSS to IHSSs, the network follows the Turing type symmetry breaking pitchfork or transcritical bifurcation depending upon the system dynamics.« less

  15. Absorption band oscillator strengths of N2 transitions between 95.8 and 99.4 nm

    NASA Technical Reports Server (NTRS)

    Stark, G.; Smith, Peter L.; Huber, K. P.; Yoshino, K.; Stevens, M. H.; Ito, K.

    1992-01-01

    Molecular nitrogen plays a central role in the energetics of the earth's upper atmosphere and is the major constituent of the atmospheres of the planetary satellites Titan and Triton. This paper reports a new set of absorption oscillator strengths measured at higher resolution for seven bands in the 95.8-99.4 nm region. The results are compared with earlier, lower resolution absorption measurements, electron scattering measurements, and calculations based on a deperturbation analysis of the excited states.

  16. The International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas

    NASA Technical Reports Server (NTRS)

    Sugar, J.; Leckrone, D.

    1993-01-01

    This was the fourth in a series of colloquia begun at the University of Lund, Sweden in 1983 and subsequently held in Toledo, Ohio and Amsterdam, The Netherlands. The purpose of these meetings is to provide an international forum for communication between major users of atomic spectroscopic data and the providers of these data. These data include atomic wavelengths, line shapes, energy levels, lifetimes, and oscillator strengths. Speakers were selected from a wide variety of disciplines including astrophysics, laboratory plasma research, spectrochemistry, and theoretical and experimental atomic physics.

  17. Improved Wavelengths and Oscillator Strengths of Cr III, Co III, and Fe III

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Smillie, D. G.; Pickering, J. C.; Blackwell-Whitehead, R. J.

    2008-05-01

    Improvements in the resolution, accuracy, and range of spectra obtained by state-of-the-art space- and ground-based astronomical spectrographs have demonstrated a need for corresponding improvements in atomic data. Transition wavelengths with uncertainties of 1 part in 10^7 and oscillator strengths (f-values) with uncertainties of 10 to 15% are needed to accurately interpret modern astrophysical spectra. Our focus has been on spectra of doubly ionized iron group elements that dominate the UV spectra of hot B stars. We report here completion of measurements on Cr III, Co III, Fe III made with a UV high resolution Fourier transform spectrometer (FTS) [J. C. Pickering, Vibrational Spectrosc. 29, 27 (2002)] with a typical wavelength/wavenumber uncertainty of a few parts in 10^8, supplemented by measurements were carried out at the US National Institute of Standards & Technology using their FTS and the Normal Incidence Vacuum (grating) Spectrograph (NIVS). The spectra were analyzed and line lists were produced to give calibrated line wavelengths and relative intensities. Measured wavelengths are, in many cases, an order of magnitude more accurate than previous measurements, and the energy level uncertainties are typically reduced by a factor or 3 more. Summaries of submitted papers on Cr III and Co III will be presented, as will work on improved wavelengths, energy levels, and oscillator strengths for Fe III. Limitations to the method and possible solutions will be discussed. This work is, or has been, supported in part by NASA Grant NAG5-12668; NASA inter-agency agreement W-10255; PPARC; the Royal Society of the UK; and by the Leverhulme Trust.

  18. Einstein coefficients and oscillator strengths for low lying state of CO molecules

    NASA Astrophysics Data System (ADS)

    Swer, S.; Syiemiong, A.; Ram, M.; Jha, A. K.; Saxena, A.

    2018-04-01

    Einstein Coefficients and Oscillator Strengths for different state of CO molecule have been calculated using LEROY'S LEVEL program and MOLCAS ab initio code. Using the wave function derived from Morse potential and transition dipole moment obtained from ab initio calculation, The potential energy functions were computed for these states using the spectroscopic constants. The Morse potential of these states and electronic transition dipole moment of the transition calculated in a recent ab initio study have been used in LEVEL program to produce transition dipole matrix element for a large number of bands. Einstein Coefficients have also been used to compute the radiative lifetimes of several vibrational levels and the calculated values are compared with other theoretical results and experimental values.

  19. Finite-size scaling in the system of coupled oscillators with heterogeneity in coupling strength

    NASA Astrophysics Data System (ADS)

    Hong, Hyunsuk

    2017-07-01

    We consider a mean-field model of coupled phase oscillators with random heterogeneity in the coupling strength. The system that we investigate here is a minimal model that contains randomness in diverse values of the coupling strength, and it is found to return to the original Kuramoto model [Y. Kuramoto, Prog. Theor. Phys. Suppl. 79, 223 (1984), 10.1143/PTPS.79.223] when the coupling heterogeneity disappears. According to one recent paper [H. Hong, H. Chaté, L.-H. Tang, and H. Park, Phys. Rev. E 92, 022122 (2015), 10.1103/PhysRevE.92.022122], when the natural frequency of the oscillator in the system is "deterministically" chosen, with no randomness in it, the system is found to exhibit the finite-size scaling exponent ν ¯=5 /4 . Also, the critical exponent for the dynamic fluctuation of the order parameter is found to be given by γ =1 /4 , which is different from the critical exponents for the Kuramoto model with the natural frequencies randomly chosen. Originally, the unusual finite-size scaling behavior of the Kuramoto model was reported by Hong et al. [H. Hong, H. Chaté, H. Park, and L.-H. Tang, Phys. Rev. Lett. 99, 184101 (2007), 10.1103/PhysRevLett.99.184101], where the scaling behavior is found to be characterized by the unusual exponent ν ¯=5 /2 . On the other hand, if the randomness in the natural frequency is removed, it is found that the finite-size scaling behavior is characterized by a different exponent, ν ¯=5 /4 [H. Hong, H. Chaté, L.-H. Tang, and H. Park, Phys. Rev. E 92, 022122 (2015), 10.1103/PhysRevE.92.022122]. Those findings brought about our curiosity and led us to explore the effects of the randomness on the finite-size scaling behavior. In this paper, we pay particular attention to investigating the finite-size scaling and dynamic fluctuation when the randomness in the coupling strength is considered.

  20. Effect of oscillator strength and intermediate resonance on the performance of resonant phonon-based terahertz quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Fathololoumi, S.; Dupont, E.; Wasilewski, Z. R.; Chan, C. W. I.; Razavipour, S. G.; Laframboise, S. R.; Huang, Shengxi; Hu, Q.; Ban, D.; Liu, H. C.

    2013-03-01

    We experimentally investigated the effect of oscillator strength (radiative transition diagonality) on the performance of resonant phonon-based terahertz quantum cascade lasers that have been optimized using a simplified density matrix formalism. Our results show that the maximum lasing temperature (Tmax) is roughly independent of laser transition diagonality within the lasing frequency range of the devices under test (3.2-3.7 THz) when cavity loss is kept low. Furthermore, the threshold current can be lowered by employing more diagonal transition designs, which can effectively suppress parasitic leakage caused by intermediate resonance between the injection and the downstream extraction levels. Nevertheless, the current carrying capacity through the designed lasing channel in more diagonal designs may sacrifice even more, leading to electrical instability and, potentially, complete inhibition of the device's lasing operation. We propose a hypothesis based on electric-field domain formation and competition/switching of different current-carrying channels to explain observed electrical instability in devices with lower oscillator strengths. The study indicates that not only should designers maximize Tmax during device optimization but also they should always consider the risk of electrical instability in device operation.

  1. Electrical tuning of the oscillator strength in type II InAs/GaInSb quantum wells for active region of passively mode-locked interband cascade lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, Mateusz; Motyka, Marcin; Kurka, Marcin; Ryczko, Krzysztof; Misiewicz, Jan; Schade, Anne; Kamp, Martin; Höfling, Sven; Sęk, Grzegorz

    2017-11-01

    Two designs of active region for an interband cascade laser, based on double or triple GaInSb/InAs type II quantum wells (QWs), were compared with respect to passive mode-locked operation in the mid-infrared range around 4 µm. The layer structure and electron and hole wavefunctions under external electric field were engineered to allow controlling the optical transition oscillator strength and the resulting lifetimes. As a result, the investigated structures can mimic absorber-like and gain-like sections of a mode-locked device when properly polarized with opposite bias. A significantly larger oscillator strength tuning range for triple QWs was experimentally verified by Fourier-transform photoreflectance.

  2. Strongly nonlinear theory of rapid solidification near absolute stability

    NASA Astrophysics Data System (ADS)

    Kowal, Katarzyna N.; Altieri, Anthony L.; Davis, Stephen H.

    2017-10-01

    We investigate the nonlinear evolution of the morphological deformation of a solid-liquid interface of a binary melt under rapid solidification conditions near two absolute stability limits. The first of these involves the complete stabilization of the system to cellular instabilities as a result of large enough surface energy. We derive nonlinear evolution equations in several limits in this scenario and investigate the effect of interfacial disequilibrium on the nonlinear deformations that arise. In contrast to the morphological stability problem in equilibrium, in which only cellular instabilities appear and only one absolute stability boundary exists, in disequilibrium the system is prone to oscillatory instabilities and a second absolute stability boundary involving attachment kinetics arises. Large enough attachment kinetics stabilize the oscillatory instabilities. We derive a nonlinear evolution equation to describe the nonlinear development of the solid-liquid interface near this oscillatory absolute stability limit. We find that strong asymmetries develop with time. For uniform oscillations, the evolution equation for the interface reduces to the simple form f''+(βf')2+f =0 , where β is the disequilibrium parameter. Lastly, we investigate a distinguished limit near both absolute stability limits in which the system is prone to both cellular and oscillatory instabilities and derive a nonlinear evolution equation that captures the nonlinear deformations in this limit. Common to all these scenarios is the emergence of larger asymmetries in the resulting shapes of the solid-liquid interface with greater departures from equilibrium and larger morphological numbers. The disturbances additionally sharpen near the oscillatory absolute stability boundary, where the interface becomes deep-rooted. The oscillations are time-periodic only for small-enough initial amplitudes and their frequency depends on a single combination of physical parameters, including the

  3. Calculations of the energy levels and oscillator strengths of the Ne-like Fe Ion (Fe XVII)

    NASA Astrophysics Data System (ADS)

    Zhong, Jia-yong; Zhang, Jie; Zhao, Gang; Lu, Xin

    Energy levels and oscillator strengths among the 27 fine-structure levels belonging to the (ls 22s 2)2p 6, 2p 53s, 2p 53p and 2p 53d configurations of the neon-like iron ion have been calculated using three atomic structure codes RCN/RCG, AUTOSTRUCTURE (AS) and GRASP. Relativistic corrections of the wave functions are taken into account in the RCN/RCG calculation. The results agree well with the available experimental and theoretical data. The accuracy of the three codes is analysed.

  4. Generalizing the transition from amplitude to oscillation death in coupled oscillators.

    PubMed

    Zou, Wei; Senthilkumar, D V; Koseska, Aneta; Kurths, Jürgen

    2013-11-01

    Amplitude death (AD) and oscillation death (OD) are two structurally different oscillation quenching types in coupled nonlinear oscillators. The transition from AD to OD has been recently realized due to the interplay between heterogeneity and coupling strength [A. Koseska et al., Phys. Rev. Lett. 111, 024103 (2013)]. We identify here the transition from AD to OD in nonlinear oscillators with couplings of distinct natures. It is demonstrated that the presence of time delay in the coupling cannot induce such a transition in identical oscillators, but it can indeed facilitate its occurrence with a low degree of heterogeneity. Moreover, it is further shown that the AD to OD transition is reliably observed in identical oscillators with dynamic and conjugate couplings. The coexistence of AD and OD and rich stable OD configurations after the transition are revealed, which are of great significance for potential applications in physics, biology, and control studies.

  5. Stellar Laboratories: New GeV and Ge VI Oscillator Strengths and their Validation in the Hot White Dwarf RE0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Werner, K.; Biemont, E.; Quinet, P.; Kruk, J. W.

    2013-01-01

    State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elements. Especially data for the latter has only been sparsely calculated. Many of their lines are identified in spectra of extremely hot, hydrogen-deficient post-AGB stars. A reliable determination of their abundances establishes crucial constraints for AGB nucleosynthesis simulations and, thus, for stellar evolutionary theory. Aims. In a previous analysis of the UV spectrum of RE 0503-289, spectral lines of highly ionized Ga, Ge, As, Se, Kr, Mo, Sn, Te, I, and Xe were identified. Individual abundance determinations are hampered by the lack of reliable oscillator strengths. Most of these identified lines stem from Ge V. In addition, we identified Ge VI lines for the first time. We calculated Ge V and Ge VI oscillator strengths in order to reproduce the observed spectrum. Methods. We newly calculated Ge V and Ge VI oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our non-LTE stellar-atmosphere models for the analysis of the Ge IV-VI spectrum exhibited in high-resolution and high-S/N FUV (FUSE) and UV (ORFEUS/BEFS, IUE) observations of RE 0503-289. Results. In the UV spectrum of RE 0503-289, we identify four Ge IV, 37 Ge V, and seven Ge VI lines. Most of these lines are identified for the first time in any star. We can reproduce almost all Ge IV, GeV, and Ge VI lines in the observed spectrum of RE 0503-289 (T(sub eff) = 70 kK, log g = 7.5) at log Ge = -3.8 +/- 0.3 (mass fraction, about 650 times solar). The Ge IV/V/VI ionization equilibrium, that is a very sensitive T(sub eff) indicator, is reproduced well. Conclusions. Reliable measurements and calculations of atomic data are a

  6. Oscillator strength and quantum-confined Stark effect of excitons in a thin PbS quantum disk

    NASA Astrophysics Data System (ADS)

    Oukerroum, A.; El-Yadri, M.; El Aouami, A.; Feddi, E.; Dujardin, F.; Duque, C. A.; Sadoqi, M.; Long, G.

    2018-01-01

    In this paper, we report a study of the effect of a lateral electric field on a quantum-confined exciton in a thin PbS quantum disk. Our approach was performed in the framework of the effective mass theory and adiabatic approximation. The ground state energy and the stark shift were determined by using a variational method with an adequate trial wavefunction, by investigating a 2D oscillator strength under simultaneous consideration of the geometrical confinement and the electric field strength. Our results showed a strong dependence of the exciton binding and the Stark shift on the disk dimensions in both axial and longitudinal directions. On the other hand, our results also showed that the Stark shift’s dependence on the electric field is not purely quadratic but the linear contribution is also important and cannot be neglected, especially when the confinement gets weaker.

  7. Dipole oscillator strength distributions with improved high-energy behavior: Dipole sum rules and dispersion coefficients for Ne, Ar, Kr, and Xe revisited

    NASA Astrophysics Data System (ADS)

    Kumar, Ashok; Thakkar, Ajit J.

    2010-02-01

    The construction of the dipole oscillator strength distribution (DOSD) from theoretical and experimental photoabsorption cross sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule and molar refractivity data is a well-established technique that has been successfully applied to more than 50 species. Such DOSDs are insufficiently accurate at large photon energies. A novel iterative procedure is developed that rectifies this deficiency by using the high-energy asymptotic behavior of the dipole oscillator strength density as an additional constraint. Pilot applications are made for the neon, argon, krypton, and xenon atoms. The resulting DOSDs improve the agreement of the predicted S2 and S1 sum rules with ab initio calculations while preserving the accuracy of the remainder of the moments. Our DOSDs exploit new and more accurate experimental data. Improved estimates of dipole properties for these four atoms and of dipole-dipole C6 and triple-dipole C9 dispersion coefficients for the interactions among them are reported.

  8. Vii. New Kr IV - VII Oscillator Strengths and an Improved Spectral Analysis of the Hot, Hydrogen-deficient Do-type White Dwarf RE 0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Richter, P.; Kruk, J. W.; Demleitner, M.

    2016-01-01

    For the spectral analysis of high-resolution and high signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. New Krivvii oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTEmodel-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods. We calculated Krivvii oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high SN ultraviolet (UV)observations of the hot white dwarf RE 0503.

  9. Oscillator strengths, first-order properties, and nuclear gradients for local ADC(2).

    PubMed

    Schütz, Martin

    2015-06-07

    We describe theory and implementation of oscillator strengths, orbital-relaxed first-order properties, and nuclear gradients for the local algebraic diagrammatic construction scheme through second order. The formalism is derived via time-dependent linear response theory based on a second-order unitary coupled cluster model. The implementation presented here is a modification of our previously developed algorithms for Laplace transform based local time-dependent coupled cluster linear response (CC2LR); the local approximations thus are state specific and adaptive. The symmetry of the Jacobian leads to considerable simplifications relative to the local CC2LR method; as a result, a gradient evaluation is about four times less expensive. Test calculations show that in geometry optimizations, usually very similar geometries are obtained as with the local CC2LR method (provided that a second-order method is applicable). As an exemplary application, we performed geometry optimizations on the low-lying singlet states of chlorophyllide a.

  10. MgH Rydberg series: Transition energies from electron propagator theory and oscillator strengths from the molecular quantum defect orbital method

    NASA Astrophysics Data System (ADS)

    Corzo, H. H.; Velasco, A. M.; Lavín, C.; Ortiz, J. V.

    2018-02-01

    Vertical excitation energies belonging to several Rydberg series of MgH have been inferred from 3+ electron-propagator calculations of the electron affinities of MgH+ and are in close agreement with experiment. Many electronically excited states with n > 3 are reported for the first time and new insight is given on the assignment of several Rydberg series. Valence and Rydberg excited states of MgH are distinguished respectively by high and low pole strengths corresponding to Dyson orbitals of electron attachment to the cation. By applying the Molecular Quantum Defect Orbital method, oscillator strengths for electronic transitions involving Rydberg states also have been determined.

  11. Clausius inequality beyond the weak-coupling limit: the quantum Brownian oscillator.

    PubMed

    Kim, Ilki; Mahler, Günter

    2010-01-01

    We consider a quantum linear oscillator coupled at an arbitrary strength to a bath at an arbitrary temperature. We find an exact closed expression for the oscillator density operator. This state is noncanonical but can be shown to be equivalent to that of an uncoupled linear oscillator at an effective temperature T*(eff) with an effective mass and an effective spring constant. We derive an effective Clausius inequality deltaQ*(eff)< or =T*(eff)dS , where deltaQ*(eff) is the heat exchanged between the effective (weakly coupled) oscillator and the bath, and S represents a thermal entropy of the effective oscillator, being identical to the von-Neumann entropy of the coupled oscillator. Using this inequality (for a cyclic process in terms of a variation of the coupling strength) we confirm the validity of the second law. For a fixed coupling strength this inequality can also be tested for a process in terms of a variation of either the oscillator mass or its spring constant. Then it is never violated. The properly defined Clausius inequality is thus more robust than assumed previously.

  12. Weak Perturbations of Biochemical Oscillators

    NASA Astrophysics Data System (ADS)

    Gailey, Paul

    2001-03-01

    Biochemical oscillators may play important roles in gene regulation, circadian rhythms, physiological signaling, and sensory processes. These oscillations typically occur inside cells where the small numbers of reacting molecules result in fluctuations in the oscillation period. Some oscillation mechanisms have been reported that resist fluctuations and produce more stable oscillations. In this paper, we consider the use of biochemical oscillators as sensors by comparing inherent fluctuations with the effects of weak perturbations to one of the reactants. Such systems could be used to produce graded responses to weak stimuli. For example, a leading hypothesis to explain geomagnetic navigation in migrating birds and other animals is based on magnetochemical reactions. Because the magnitude of magnetochemical effects is small at geomagnetic field strengths, a sensitive, noise resistant detection scheme would be required.

  13. A probabilistic analysis of the crystal oscillator behavior at low drive levels

    NASA Astrophysics Data System (ADS)

    Shmaliy, Yuriy S.; Brendel, Rémi

    2008-03-01

    The paper discusses a probabilistic model of a crystal oscillator at low drive levels where the noise intensity is comparable with the oscillation amplitude. The stationary probability density of the oscillations envelope is derived and investigated for the nonlinear resonator loses. A stochastic explanation is given for the well-known phenomenon termed sleeping sickness associated with losing a facility of self-excitation by a crystal oscillator after a long storage without a power supply. It is shown that, with low drive levels leading to an insufficient feedback, a crystal oscillator generates the noise-induced oscillations rather than it absolutely "falls in sleep".

  14. Frequency-locked chaotic opto-RF oscillator.

    PubMed

    Thorette, Aurélien; Romanelli, Marco; Brunel, Marc; Vallet, Marc

    2016-06-15

    A driven opto-RF oscillator, consisting of a dual-frequency laser (DFL) submitted to frequency-shifted feedback, is experimentally and numerically studied in a chaotic regime. Precise control of the reinjection strength and detuning permits isolation of a parameter region of bounded-phase chaos, where the opto-RF oscillator is frequency-locked to the master oscillator, in spite of chaotic phase and intensity oscillations. Robust experimental evidence of this synchronization regime is found, and phase noise spectra allow us to compare phase-locking and bounded-phase chaos regimes. In particular, it is found that the long-term phase stability of the master oscillator is well transferred to the opto-RF oscillator, even in the chaotic regime.

  15. Noise promotes independent control of gamma oscillations and grid firing within recurrent attractor networks

    PubMed Central

    Solanka, Lukas; van Rossum, Mark CW; Nolan, Matthew F

    2015-01-01

    Neural computations underlying cognitive functions require calibration of the strength of excitatory and inhibitory synaptic connections and are associated with modulation of gamma frequency oscillations in network activity. However, principles relating gamma oscillations, synaptic strength and circuit computations are unclear. We address this in attractor network models that account for grid firing and theta-nested gamma oscillations in the medial entorhinal cortex. We show that moderate intrinsic noise massively increases the range of synaptic strengths supporting gamma oscillations and grid computation. With moderate noise, variation in excitatory or inhibitory synaptic strength tunes the amplitude and frequency of gamma activity without disrupting grid firing. This beneficial role for noise results from disruption of epileptic-like network states. Thus, moderate noise promotes independent control of multiplexed firing rate- and gamma-based computational mechanisms. Our results have implications for tuning of normal circuit function and for disorders associated with changes in gamma oscillations and synaptic strength. DOI: http://dx.doi.org/10.7554/eLife.06444.001 PMID:26146940

  16. Relativistic many-body calculations of excitation energies, oscillator strengths, transition rates, and lifetimes in samarium like ions

    NASA Astrophysics Data System (ADS)

    Safronova, Ulyana; Safronova, Alla; Beiersdorfer, Peter

    2013-05-01

    Excitation energies, oscillator strengths, transition probabilities, and lifetimes are calculated for (5s2 + 5p2 + 5d2 + 5 s 5 d + 5 s 5 g + 5 p 5 f) - (5 s 5 p + 5 s 5 f + 5 p 5 d + 5 p 5 g) electric dipole transitions in Sm-like ions with nuclear charge Z ranging from 74 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 Dirac-Fock potential. First-order perturbation theory is used to obtain intermediate coupling coefficients, and the second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order E1 matrix elements to achieve agreement between length-form and velocity-form amplitudes. The resulting transition energies and transition probabilities, and lifetimes for Sm-like W12+ are compared with results obtained by the relativistic Hartree-Fock approximation (COWAN code) to estimate contribution of the 4 f -core-excited states. Trends of excitation energies and oscillator strengths as function of nuclear charge Z are shown graphically for selected states and transitions. This work provides a number of yet unmeasured properti. This research was sponsored by the grant DE-FG02-08ER54951.

  17. Oscillator strengths of the optical transitions in a semiconductor superlattice under an electric field

    NASA Astrophysics Data System (ADS)

    Tronc, P.

    1992-04-01

    The oscillator strengths of the optical transitions in a semiconductor superlattice under an electric field parallel to the growth axis can be calculated using a perturbative model with Bloch envelope functions. The applied electric field and the electron-hole interaction inducing formation of indirect excitons both induce strength asymmetry between the oblique +p and -p transitions of the Wannier-Stark ladder. Features of the photocurrent spectra recorded at low temperature can be accounted for by the present model in a very simple manner. Les forces d'oscillateur des transitions optiques dans un superréseau semiconducteur soumis à un champ électrique parallèle à la direction de croissance, peuvent être calculées à l'aide d'un modèle de perturbation avec des fonctions enveloppes de Bloch. Le champ électrique appliqué ainsi que l'interaction électron-trou, qui induit la formation d'excitons indirects, entraînent une asymétrie entre les forces d'oscillateur des transitions +p et -p dans l'échelle de Wannier-Stark. Certaines caractéristiques des spectres de photocourant enregistrés à basse température peuvent être prévues d'une manière très simple.

  18. What formulas are good for representing dipole and generalized oscillator-strength spectra

    NASA Astrophysics Data System (ADS)

    Inokuti, M.; Dillon, M. A.

    The dipole oscillator-strength distribution df/depsilon for a single continuum excitation of an atom or molecule is a function of the kinetic energy epsilon of an outgoing electron. The distribution describes many optical phenomena such as absorption, refraction, and reflection; in particular, df/depsilon is equal to the cross section for ionization by a photon with energy epsilon + I, apart from an universal constant, where I is the ionization threshold for the relevant shell. Furthermore, df/depsilon governs the ionization by glancing collisions of fast charged particles. Recent years have seen considerable accumulation of experimental data on df/depsilon. Those data are indeed valuable for many aplications in radiation physics, plasma physics, atmospheric physics, and astrophysics. In most of these applications, one needs a comprehensive set of data, i.e., numerical values of df/depsilon over a wide range of epsilon, say, from several eV to many keV; most often, one needs data at all epsilon at which df/depsilon is appreciable. A method for systematizing the data so that one can extrapolate or interpolate them dependably was sought.

  19. Stellar laboratories: new Ge V and Ge VI oscillator strengths and their validation in the hot white dwarf RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Biémont, É.; Quinet, P.; Kruk, J. W.

    2012-10-01

    Context. State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elements. Especially data for the latter has only been sparsely calculated. Many of their lines are identified in spectra of extremely hot, hydrogen-deficient post-AGB stars. A reliable determination of their abundances establishes crucial constraints for AGB nucleosynthesis simulations and, thus, for stellar evolutionary theory. Aims: In a previous analysis of the UV spectrum of RE 0503-289, spectral lines of highly ionized Ga, Ge, As, Se, Kr, Mo, Sn, Te, I, and Xe were identified. Individual abundance determinations are hampered by the lack of reliable oscillator strengths. Most of these identified lines stem from Ge V. In addition, we identified Ge VI lines for the first time. We calculated Ge V and Ge VI oscillator strengths in order to reproduce the observed spectrum. Methods: We newly calculated Ge V and Ge VI oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our non-LTE stellar-atmosphere models for the analysis of the Ge iv-vi spectrum exhibited in high-resolution and high-S/N FUV (FUSE) and UV (ORFEUS/BEFS, IUE) observations of RE 0503-289. Results: In the UV spectrum of RE 0503-289, we identify four Ge IV, 37 Ge V, and seven Ge VI lines. Most of these lines are identified for the first time in any star. We can reproduce almost all Ge IV, Ge V, and Ge VI lines in the observed spectrum of RE 0503-289 (Teff = 70 kK, log g = 7.5) at log Ge = -3.8 ± 0.3 (mass fraction, about 650 times solar). The Ge iv/v/vi ionization equilibrium, that is a very sensitive Teff indicator, is reproduced well. Conclusions: Reliable measurements and calculations of atomic data are a

  20. Stellar Laboratories . [VI. New Mo IV - VII Oscillator Strengths and the Molybdenum Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Quinet, T.; Hoyer, D.; Werner, K.; Demleitner, M.; Kruk, J. W.

    2016-01-01

    For the spectral analysis of high-resolution and high signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To identify molybdenum lines in the ultraviolet (UV) spectra of the DA-type white dwarf G191B2B and the DO-type white dwarf RE 0503289 and, to determine their photospheric Mo abundances, reliable Mo iv-vii oscillator strengths are used. Methods: We newly calculated Mo iv-vii oscillator strengths to consider their radiative and collisional bound-bound transitions indetail in our NLTE stellar-atmosphere models for the analysis of Mo lines exhibited in high-resolution and high SN UV observations of RE 0503289.Results. We identified 12 Mo v and nine Mo vi lines in the UV spectrum of RE 0503289 and measured a photospheric Mo abundance of 1.2 3.0 104(mass fraction, 22 500 56 400 times the solar abundance). In addition, from the As v and Sn iv resonance lines,we measured mass fractions of arsenic (0.51.3 105, about 300 1200 times solar) and tin (1.33.2 104, about 14 300 35 200 times solar). For G191B2B, upper limits were determined for the abundances of Mo (5.3 107, 100 times solar) and, in addition, for Kr (1.1106, 10 times solar) and Xe (1.7107, 10 times solar). The arsenic abundance was determined (2.35.9 107, about 21 53 times solar). A new, registered German Astrophysical Virtual Observatory (GAVO) service, TOSS, has been constructed to provide weighted oscillator strengths and transition probabilities.Conclusions. Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Observed Mo v-vi line profiles in the UV spectrum of the white dwarf RE 0503289 were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed the photospheric Mo abundance in a white dwarf to be determined.

  1. Rayleigh-type parametric chemical oscillation.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

  2. [Absolute and relative strength-endurance of the knee flexor and extensor muscles: a reliability study using the IsoMed 2000-dynamometer].

    PubMed

    Dirnberger, J; Wiesinger, H P; Stöggl, T; Kösters, A; Müller, E

    2012-09-01

    Isokinetic devices are highly rated in strength-related performance diagnosis. A few years ago, the broad variety of existing products was extended by the IsoMed 2000-dynamometer. In order for an isokinetic device to be clinically useful, the reliability of specific applications must be established. Although there have already been single studies on this topic for the IsoMed 2000 concerning maximum strength measurements, there has been no study regarding the assessment of strength-endurance so far. The aim of the present study was to establish the reliability for various methods of quantification of strength-endurance using the IsoMed 2000. A sample of 33 healthy young subjects (age: 23.8 ± 2.6 years) participated in one familiarisation and two testing sessions, 3-4 days apart. Testing consisted of a series 30 full effort concentric extension-flexion cycles of the right knee muscles at an angular velocity of 180 °/s. Based on the parameters Peak, Torque and Work for each repetition, indices of absolute (KADabs) and relative (KADrel) strength-endurance were derived. KADabs was calculated as the mean value of all testing repetitions, KADrel was determined in two ways: on the one hand, as the percentage decrease between the first and the last 5 repetitions (KADrelA) and on the other, as the negative slope derived from the linear regression equitation of all repetitions (KADrelB). Detection of systematic errors was performed using paired sample t-tests, relative and absolute reliability were examined using intraclass correlation coefficient (ICC 2.1) and standard error of measurement (SEM%), respectively. In general, for extension measurements concerning KADabs and - in an weakened form - KADrel high ICC -values of 0.76-0.89 combined with clinically acceptable values of SEM% of 1.2-5.9 % could be found. For flexion measurements this only applies to KADabs, whereas results for KADrel turned out to be clearly weaker with ICC- and SEM% values of 0.42-0.62 and 9

  3. Chemical factors determine olfactory system beta oscillations in waking rats.

    PubMed

    Lowry, Catherine A; Kay, Leslie M

    2007-07-01

    Recent studies have pointed to olfactory system beta oscillations of the local field potential (15-30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associative learning, we tested rats with 26 monomolecular odorants spanning 6 log units of theoretical vapor pressure (estimate of relative vapor phase concentration) and 10 different odor mixtures. We found odorant vapor phase concentration to be inversely correlated with investigation time on the first presentation, after which investigation times were brief and not different across odorants. Analysis of local field potentials from the olfactory bulb and anterior piriform cortex shows that beta oscillations in waking rats occur specifically in response to the class of volatile organic compounds with vapor pressures of 1-120 mmHg. Beta oscillations develop over the first three to four presentations and are weakly present for some odorants in anesthetized rats. Gamma oscillations show a smaller effect that is not restricted to the same range of odorants. Olfactory bulb theta oscillations were also examined as a measure of effective afferent input strength, and the power of these oscillations did not vary systematically with vapor pressure, suggesting that it is not olfactory bulb drive strength that determines the presence of beta oscillations. Theta band coherence analysis shows that coupling strength between the olfactory bulb and piriform cortex increases linearly with vapor phase concentration, which may facilitate beta oscillations above a threshold.

  4. Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sulfur-like iron, Fe XI

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

    Abou El-Maaref, A., E-mail: aahmh@hotmail.com; Ahmad, Mahmoud; Allam, S.H.

    Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s{sup 2}3p{sup 4}, 3s3p{sup 5}, 3s{sup 2}3p{sup 3}3d, 3s{sup 2}3p{sup 3}4s, 3s{sup 2}3p{sup 3}4p, and 3s{sup 2}3p{sup 3}4d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit–Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term,more » and spin–orbit, spin–other-orbit, and spin–spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications. -- Highlights: •Accurate atomic data of iron ions are needed for identification of solar corona. •Extensive configuration interaction wavefunctions including 123 fine-structure levels have been calculated. •The relativistic effects by means of the Breit–Pauli Hamiltonian terms are incorporated. •This incorporation adjusts the energy levels, therefore the calculated values are close to experimental values.« less

  5. Chemotaxis and Actin Oscillations

    NASA Astrophysics Data System (ADS)

    Bodenschatz, Eberhard; Hsu, Hsin-Fang; Negrete, Jose; Beta, Carsten; Pumir, Alain; Gholami, Azam; Tarantola, Marco; Westendorf, Christian; Zykov, Vladimir

    Recently, self-oscillations of the cytoskeletal actin have been observed in Dictyostelium, a model system for studying chemotaxis. Here we report experimental results on the self-oscillation mechanism and the role of regulatory proteins and myosin II. We stimulate cells rapidly and periodically by using photo un-caging of the chemoattractant in a micro-fluidic device and measured the cellular responses. We found that the response amplitude grows with stimulation strength only in a very narrow region of stimulation, after which the response amplitude reaches a plateau. Moreover, the frequency-response is not constant but rather varies with the strength of external stimuli. To understand the underlying mechanism, we analyzed the polymerization and de-polymerization time in the single cell level. Despite of the large cell-to-cell variability, we found that the polymerization time is independent of external stimuli and the de-polymerization time is prolonged as the stimulation strength increases. Our conclusions will be summarized and the role of noise in the signaling network will be discussed. German Science Foundation CRC 937.

  6. Energy levels, oscillator strengths, line strengths, and transition probabilities in Si-like ions of La XLIII, Er LIV, Tm LV, and Yb LVI

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

    Chen, Zhan-Bin, E-mail: chenzb008@qq.com; Ma, Kun; Wang, Hong-Jian

    2017-01-15

    Detailed calculations using the multi-configuration Dirac–Fock (MCDF) method are carried out for the lowest 64 fine-structure levels of the 3s{sup 2}3p{sup 2}, 3s{sup 2}3p3d, 3s3p{sup 3}, 3s3p{sup 2}3d, 3s{sup 2}3d{sup 2}, and 3p{sup 4} configurations in Si-like ions of La XLIII, Er LIV, Tm LV, and Yb LVI. Energies, oscillator strengths, wavelengths, line strengths, and radiative electric dipole transition rates are given for all ions. A parallel calculation using the many-body perturbation theory (MBPT) method is also carried out to assess the present energy levels accuracy. Comparisons are performed between these two sets of energy levels, as well as withmore » other available results, showing that they are in good agreement with each other within 0.5%. These high accuracy results can be used to the modeling and the interpretation of astrophysical objects and fusion plasmas. - Highlights: • Energy levels and E1 transition rates of Si-like ions are presented. • Breit interaction and Quantum Electrodynamics effects are discussed. • Present results should be useful in the astrophysical application and plasma modeling.« less

  7. Global dynamics of a stochastic neuronal oscillator

    NASA Astrophysics Data System (ADS)

    Yamanobe, Takanobu

    2013-11-01

    Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.

  8. Global dynamics of a stochastic neuronal oscillator.

    PubMed

    Yamanobe, Takanobu

    2013-11-01

    Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.

  9. Aging transition in systems of oscillators with global distributed-delay coupling.

    PubMed

    Rahman, B; Blyuss, K B; Kyrychko, Y N

    2017-09-01

    We consider a globally coupled network of active (oscillatory) and inactive (nonoscillatory) oscillators with distributed-delay coupling. Conditions for aging transition, associated with suppression of oscillations, are derived for uniform and gamma delay distributions in terms of coupling parameters and the proportion of inactive oscillators. The results suggest that for the uniform distribution increasing the width of distribution for the same mean delay allows aging transition to happen for a smaller coupling strength and a smaller proportion of inactive elements. For gamma distribution with sufficiently large mean time delay, it may be possible to achieve aging transition for an arbitrary proportion of inactive oscillators, as long as the coupling strength lies in a certain range.

  10. An absolute measure for a key currency

    NASA Astrophysics Data System (ADS)

    Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

    It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

  11. Low noise cryogenic dielectric resonator oscillator

    NASA Technical Reports Server (NTRS)

    Dick, G. John (Inventor)

    1988-01-01

    A microwave oscillator is provided which can operate at a temperature of many degrees above absolute zero while providing very low phase noise that has heretofore generally required temperatures within a few degrees K. The oscillator includes a ring-shaped resonant element of ruby (sapphire plus chromium) or iron sapphire crystal, lying adjacent to a resonator element of sapphire, so that the regenerator element lies directly in the magnetic field of the resonator element. The resonator element is substantially devoid of contact with electrically conductive material. Microwave energy of a pump frequency (e.g., 31 GHz) is outputted from the regenerator element, while signal energy (e.g., 10 GHz) is outputted from the resonator element.

  12. Absolute neutrino mass measurements

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

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments inmore » Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.« less

  13. Oscillator strengths of some Ba lines - A treatment including core-valence correlation and relativistic effects

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Jaffe, R. L.; Langhoff, S. R.; Partridge, H.; Mascarello, F. G.

    1985-01-01

    Theoretical calculations of selected excitation energies and oscillator strengths for Ba are presented that overcome the difficulties of previous theoretical treatments. A relativistic effective-core potential treatment is used to account for the relativistic core contraction, but the outermost ten electrons are treated explicitly. Core-valence correlation can be included in this procedure in a rigorous and systematic way through a configuration-interaction calculation. Insight is gained into the importance of relativistic effects by repeating many of the calculations using an all-electron nonrelativistic treatment employing an extended Slater basis set. It is found that the intensity of the intercombination line 3P1-1S0 is accurately determined by accounting for the deviation from LS coupling through spin-orbit mixing with the 1P1 state, and that deviations from the Lande interval rule provide an accurate measure of the degree of mixing.

  14. Exponential bound in the quest for absolute zero

    NASA Astrophysics Data System (ADS)

    Stefanatos, Dionisis

    2017-10-01

    In most studies for the quantification of the third law of thermodynamics, the minimum temperature which can be achieved with a long but finite-time process scales as a negative power of the process duration. In this article, we use our recent complete solution for the optimal control problem of the quantum parametric oscillator to show that the minimum temperature which can be obtained in this system scales exponentially with the available time. The present work is expected to motivate further research in the active quest for absolute zero.

  15. Exponential bound in the quest for absolute zero.

    PubMed

    Stefanatos, Dionisis

    2017-10-01

    In most studies for the quantification of the third law of thermodynamics, the minimum temperature which can be achieved with a long but finite-time process scales as a negative power of the process duration. In this article, we use our recent complete solution for the optimal control problem of the quantum parametric oscillator to show that the minimum temperature which can be obtained in this system scales exponentially with the available time. The present work is expected to motivate further research in the active quest for absolute zero.

  16. Synchronization of unidirectionally delay-coupled chaotic oscillators with memory

    NASA Astrophysics Data System (ADS)

    Jaimes-Reátegui, Rider; Vera-Ávila, Victor P.; Sevilla-Escoboza, Ricardo; Huerta-Cuéllar, Guillermo; Castañeda-Hernández, Carlos E.; Chiu-Zarate, Roger; Pisarchik, Alexander N.

    2016-11-01

    We study synchronization of two chaotic oscillators coupled with time delay in a master-slave configuration and with delayed positive feedback in the slave oscillator which acts as memory. The dynamics of the slave oscillator is analyzed with bifurcation diagrams of the peak value of the system variable with respect to the coupling and feedback strengths and two delay times. For small coupling, when the oscillators' phases synchronize, memory can induce bistability and stabilize periodic orbits, whereas for stronger coupling it is not possible. The delayed feedback signal impairs synchronization, simultaneously enhancing coherence of the slave oscillator.

  17. Energy transfer and motion synchronization between mechanical oscillators through microhydrodynamic coupling

    NASA Astrophysics Data System (ADS)

    Wan, Yu; Jin, Kai; Ahmad, Talha J.; Black, Michael J.; Xu, Zhiping

    2017-03-01

    Fluidic environment is encountered for mechanical components in many circumstances, which not only damps the oscillation but also modulates their dynamical behaviors through hydrodynamic interactions. In this study, we examine energy transfer and motion synchronization between two mechanical micro-oscillators by performing thermal lattice-Boltzmann simulations. The coefficient of inter-oscillator energy transfer is measured to quantify the strength of microhydrodynamic coupling, which depends on their distance and fluid properties such as density and viscosity. Synchronized motion of the oscillators is observed in the simulations for typical parameter sets in relevant applications, with the formation and loss of stable anti-phase synchronization controlled by the oscillating frequency, amplitude, and hydrodynamic coupling strength. The critical ranges of key parameters to assure efficient energy transfer or highly synchronized motion are predicted. These findings could be used to advise mechanical design of passive and active devices that operate in fluid.

  18. Condensate oscillations in a Penrose tiling lattice

    NASA Astrophysics Data System (ADS)

    Akdeniz, Z.; Vignolo, P.

    2017-07-01

    We study the dynamics of a Bose-Einstein condensate subject to a particular Penrose tiling lattice. In such a lattice, the potential energy at each site depends on the neighbour sites, accordingly to the model introduced by Sutherland [16]. The Bose-Einstein wavepacket, initially at rest at the lattice symmetry center, is released. We observe a very complex time-evolution that strongly depends on the symmetry center (two choices are possible), on the potential energy landscape dispersion, and on the interaction strength. The condensate-width oscillates at different frequencies and we can identify large-frequency reshaping oscillations and low-frequency rescaling oscillations. We discuss in which conditions these oscillations are spatially bounded, denoting a self-trapping dynamics.

  19. The Magnetic Torque Oscillator and the Magnetic Piston

    ERIC Educational Resources Information Center

    Connors, Martin; Al-Shamali, Farook

    2007-01-01

    A magnet suspended in a uniform magnetic field like that of the Earth can be made to oscillate about the field. The frequency of oscillation depends on the strength (magnetic moment) of the magnet, that of the external field, and the moment of inertia of the magnet. It is easily shown and verified by experiment that a simple but nontrivial…

  20. Absolute and relative reliability of isokinetic and isometric trunk strength testing using the IsoMed-2000 dynamometer.

    PubMed

    Roth, Ralf; Donath, Lars; Kurz, Eduard; Zahner, Lukas; Faude, Oliver

    2017-03-01

    The present study aimed to assess the between day reliability of isokinetic and isometric peak torque (PT) during trunk measurement on an isokinetic device (IsoMed 2000). Test-retest-protocol on five separate days. Fifteen healthy sport students (8 female and 7 male) aged 21 to 26. PT was assessed in isometric back extension and flexion as well as right and left rotation. Isokinetic strength was captured at a speed of 60°/s and 150°/s for all tasks. For none of the assessed parameters a meaningful variation in PT during test days was observed. Relative reliability (ICC = 0.85-0.96) was excellent for all tasks. Estimates of absolute reliability as Coefficient of Variation (CoV) and Standard Error of Measurement (SEM in Nm/kg lean body mass) remained stable for isometric (6.9% < CoV < 9.4%; 0.15 < SEM < 0.23) and isokinetic mode (60°/s: 3.7% < CoV < 8.6%; 0.08 < SEM < 0.24; 150°/s: 6.9% < CoV < 12.4%; 0.10 < SEM < 0.31). In contrast, reliability between familiarization day and day 1 was lower (6.6% < CoV < 26.2%; 0.10 < SEM < 0.65). Trunk strength measurement in flexion and extension or trunk rotation in either isometric or isokinetic condition is highly reliable. Therefore, it seems possible to elucidate changes which are smaller than 10% due to intervention programs when a preceding familiarization condition was applied. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Stable amplitude chimera states in a network of locally coupled Stuart-Landau oscillators.

    PubMed

    Premalatha, K; Chandrasekar, V K; Senthilvelan, M; Lakshmanan, M

    2018-03-01

    We investigate the occurrence of collective dynamical states such as transient amplitude chimera, stable amplitude chimera, and imperfect breathing chimera states in a locally coupled network of Stuart-Landau oscillators. In an imperfect breathing chimera state, the synchronized group of oscillators exhibits oscillations with large amplitudes, while the desynchronized group of oscillators oscillates with small amplitudes, and this behavior of coexistence of synchronized and desynchronized oscillations fluctuates with time. Then, we analyze the stability of the amplitude chimera states under various circumstances, including variations in system parameters and coupling strength, and perturbations in the initial states of the oscillators. For an increase in the value of the system parameter, namely, the nonisochronicity parameter, the transient chimera state becomes a stable chimera state for a sufficiently large value of coupling strength. In addition, we also analyze the stability of these states by perturbing the initial states of the oscillators. We find that while a small perturbation allows one to perturb a large number of oscillators resulting in a stable amplitude chimera state, a large perturbation allows one to perturb a small number of oscillators to get a stable amplitude chimera state. We also find the stability of the transient and stable amplitude chimera states and traveling wave states for an appropriate number of oscillators using Floquet theory. In addition, we also find the stability of the incoherent oscillation death states.

  2. Stable amplitude chimera states in a network of locally coupled Stuart-Landau oscillators

    NASA Astrophysics Data System (ADS)

    Premalatha, K.; Chandrasekar, V. K.; Senthilvelan, M.; Lakshmanan, M.

    2018-03-01

    We investigate the occurrence of collective dynamical states such as transient amplitude chimera, stable amplitude chimera, and imperfect breathing chimera states in a locally coupled network of Stuart-Landau oscillators. In an imperfect breathing chimera state, the synchronized group of oscillators exhibits oscillations with large amplitudes, while the desynchronized group of oscillators oscillates with small amplitudes, and this behavior of coexistence of synchronized and desynchronized oscillations fluctuates with time. Then, we analyze the stability of the amplitude chimera states under various circumstances, including variations in system parameters and coupling strength, and perturbations in the initial states of the oscillators. For an increase in the value of the system parameter, namely, the nonisochronicity parameter, the transient chimera state becomes a stable chimera state for a sufficiently large value of coupling strength. In addition, we also analyze the stability of these states by perturbing the initial states of the oscillators. We find that while a small perturbation allows one to perturb a large number of oscillators resulting in a stable amplitude chimera state, a large perturbation allows one to perturb a small number of oscillators to get a stable amplitude chimera state. We also find the stability of the transient and stable amplitude chimera states and traveling wave states for an appropriate number of oscillators using Floquet theory. In addition, we also find the stability of the incoherent oscillation death states.

  3. Oscillator strengths of neutral titanium from hook method measurements in a furnace. I - Lines from the a 3F2, 3 and 4 levels at 0, 0.021, and 0.048 eV

    NASA Technical Reports Server (NTRS)

    Smith, P. L.; Kuehne, M.

    1978-01-01

    Oscillator strengths for 134 lines from the ground term of neutral titanium have been measured by the hook method. The data, which are normalized to those of Bell, Kalman and Tubbs, agree well with most previously measured data but indicate that there is a line strength dependent error in the National Bureau of Standards compilation of TiIf-values by Wiese and Fuhr.

  4. Absolute and relative educational inequalities in depression in Europe.

    PubMed

    Dudal, Pieter; Bracke, Piet

    2016-09-01

    To investigate (1) the size of absolute and relative educational inequalities in depression, (2) their variation between European countries, and (3) their relationship with underlying prevalence rates. Analyses are based on the European Social Survey, rounds three and six (N = 57,419). Depression is measured using the shortened Centre of Epidemiologic Studies Depression Scale. Education is coded by use of the International Standard Classification of Education. Country-specific logistic regressions are applied. Results point to an elevated risk of depressive symptoms among the lower educated. The cross-national patterns differ between absolute and relative measurements. For men, large relative inequalities are found for countries including Denmark and Sweden, but are accompanied by small absolute inequalities. For women, large relative and absolute inequalities are found in Belgium, Bulgaria, and Hungary. Results point to an empirical association between inequalities and the underlying prevalence rates. However, the strength of the association is only moderate. This research stresses the importance of including both measurements for comparative research and suggests the inclusion of the level of population health in research into inequalities in health.

  5. The splitting and oscillator strengths for the 2S/2/S-2p/2/P/0/ doublet in lithium-like sulfur. [during Skylab observed solar flares

    NASA Technical Reports Server (NTRS)

    Pegg, D. J.; Forester, J. P.; Elston, S. B.; Griffin, P. M.; Peterson, R. S.; Thoe, R. S.; Vane, C. R.; Sellin, I. A.; Groeneveld, K.-O.

    1977-01-01

    The beam-foil technique has been used to study the 2S(2)S-2p(2)P(0) doublet in S XIV. The results confirm the doublet splitting measured aboard Skylab during solar flare events. In addition, the oscillator strengths for the resonance transitions comprising this doublet have been measured and found to agree well with recent relativistic f-value calculations.

  6. High-resolution study of oscillator strengths and predissociation rates for 13C18O . W-X bands and Rydberg complexes between 92.9 and 93.5 nm

    NASA Astrophysics Data System (ADS)

    Eidelsberg, M.; Lemaire, J. L.; Federman, S. R.; Heays, A. N.; Stark, G.; Lyons, J. R.; Gavilan, L.; de Oliveira, N.

    2017-06-01

    We carried out experiments at the SOLEIL synchrotron facility to acquire data for modelling CO photochemistry in the vacuum ultraviolet. We report oscillator strengths and predissociation rates for four vibrational bands associated with transitions from the v = 0 level of the X1Σ+ ground state to the v = 0-3 vibrational levels of the core excited W1Π Rydberg state, and for three overlapping bands associated with the 4pπ, 5pπ, and 5pσ Rydberg states between 92.9 and 93.4 nm in 13C18O. These results complete those obtained in the same conditions for 12C16O, 13C16O, and 12C18O recently published by us, and extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for CO isotopologues. Absorption spectra were recorded using the Vacuum UltraViolet Fourier Transform Spectrometer (VUV-FTS) installed on the Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron (DESIRS) beamline at SOLEIL. The resolving power of the measurements, R = 300 000 to 400 000, allows the analysis of individual line strengths and widths within the bands. Gas column densities in the differentially pumped system were calibrated using the B-X (0-0) band at 115.1 nm in 13C18O.

  7. Synchronization of three electrochemical oscillators: From local to global coupling

    NASA Astrophysics Data System (ADS)

    Liu, Yifan; Sebek, Michael; Mori, Fumito; Kiss, István Z.

    2018-04-01

    We investigate the formation of synchronization patterns in an oscillatory nickel electrodissolution system in a network obtained by superimposing local and global coupling with three electrodes. We explored the behavior through numerical simulations using kinetic ordinary differential equations, Kuramoto type phase models, and experiments, in which the local to global coupling could be tuned by cross resistances between the three nickel wires. At intermediate coupling strength with predominant global coupling, two of the three oscillators, whose natural frequencies are closer, can synchronize. By adding even a relatively small amount of local coupling (about 9%-25%), a spatially organized partially synchronized state can occur where one of the two synchronized elements is in the center. A formula was derived for predicting the critical coupling strength at which full synchronization will occur independent of the permutation of the natural frequencies of the oscillators over the network. The formula correctly predicts the variation of the critical coupling strength as a function of the global coupling fraction, e.g., with local coupling the critical coupling strength is about twice than that required with global coupling. The results show the importance of the topology of the network on the synchronization properties in a simple three-oscillator setup and could provide guidelines for decrypting coupling topology from identification of synchronization patterns.

  8. Investigation of Quasi-periodic Solar Oscillations in Sunspots Based on SOHO/MDI Magnetograms

    NASA Astrophysics Data System (ADS)

    Kallunki, J.; Riehokainen, A.

    2012-10-01

    In this work we study quasi-periodic solar oscillations in sunspots, based on the variation of the amplitude of the magnetic field strength and the variation of the sunspot area. We investigate long-period oscillations between three minutes and ten hours. The magnetic field synoptic maps were obtained from the SOHO/MDI. Wavelet (Morlet), global wavelet spectrum (GWS) and fast Fourier transform (FFT) methods are used in the periodicity analysis at the 95 % significance level. Additionally, the quiet Sun area (QSA) signal and an instrumental effect are discussed. We find several oscillation periods in the sunspots above the 95 % significance level: 3 - 5, 10 - 23, 220 - 240, 340 and 470 minutes, and we also find common oscillation periods (10 - 23 minutes) between the sunspot area variation and that of the magnetic field strength. We discuss possible mechanisms for the obtained results, based on the existing models for sunspot oscillations.

  9. Control of interaction strength in a network of the true slime mold by a microfabricated structure.

    PubMed

    Takamatsu, A; Fujii, T; Endo, I

    2000-02-01

    The plasmodium of the true slime mold, Physarum polycephalum, which shows various nonlinear oscillatory phenomena, for example, in its thickness, protoplasmic streaming and concentration of intracellular chemicals, can be regarded as a collective of nonlinear oscillators. The plasmodial oscillators are interconnected by microscale tubes whose dimensions can be closely related to the strength of interaction between the oscillators. Investigation of the collective behavior of the oscillators under the conditions in which the interaction strength can be systematically controlled gives significant information on the characteristics of the system. In this study, we proposed a living model system of a coupled oscillator system in the Physarum plasmodium. We patterned the geometry and dimensions of the microscale tube structure in the plasmodium by a microfabricated structure (microstructure). As the first step, we constructed a two-oscillator system for the plasmodium that has two wells (oscillator part) and a channel (coupling part). We investigated the oscillation behavior by monitoring the thickness oscillation of the plasmodium in the microstructure with various channel widths. It was found that the oscillation behavior of two oscillators dynamically changed depending on the channel width. Based on the results of measurements of the tube dimensions and the velocity of the protoplasmic streaming in the tube, we discuss how the channel width relates to the interaction strength of the coupled oscillator system.

  10. Turbulent Boundary Layer Drag Reduction by Spanwise Wall Oscillation

    NASA Astrophysics Data System (ADS)

    Trujillo, S. M.; Bogard, D. G.; Ball, K. S.

    1997-11-01

    Changes in turbulence structure were investigated in a turbulent water boundary layer flow for which wall shear had been reduced 25 percent by spanwise wall oscillations. LDV and hot film measurements were made of streamwise and wall-normal velocities. For all wall oscillations examined, drag reduction was found to scale best with the peak velocity of the wall oscillation. Burst and sweep strength and duration were all reduced by the wall oscillation, with the greatest effects seen for the strongest events. The pdf of the velocity in the near-wall region showed greatly increased periods of low velocities, but little change was observed in the streamwise velocity autocorrelation.

  11. Coupled Oscillators System in the True Slime Mold

    NASA Astrophysics Data System (ADS)

    Takamatsu, A.; Fujii, T.; Endo, I.

    The Plasmodium of true slime mold, Physarum polycephalum, which shows various oscillatory phenomena, can be regarded as a coupled nonlinear oscillators system. The partial bodies of the Plasmodium are interconnected by microscale tubes, whose dimension can be related to the coupling strength between the plasmodial oscillators. Investigation on the collective behavior of the oscillators under the condition that the configuration of the tube structure can be manipulated gives significant information on the characteristics of the Plasmodium from the viewpoint of nonlinear dynamics. In this study, we propose a living coupled oscillators system. Using a microfabricated structure, we patterned the geometry and the dimensions of the microscale tube structure of the Plasmodium. As the first step, the Plasmodium was grown in the microstructure for coupled two oscillators system that has two wells (oscillator part) and a microchannel (coupling part). We investigated the oscillation bahavior by monitoring the thickness oscillation of Plasmodium in the strucutre with various width (W) and length (L) of microchannel. We found that there are various types of oscillation bahavior, such as anti-phase and in-phase oscillations depending on the channel dimension W and L. The present method is suitable for further studies of the network of the Plasmodium as a collective nonlinear oscillators system.

  12. Configuration-interaction relativistic-many-body-perturbation-theory calculations of photoionization cross sections from quasicontinuum oscillator strengths

    DOE PAGES

    Savukov, I. M.; Filin, D. V.

    2014-12-29

    Many applications are in need of accurate photoionization cross sections, especially in the case of complex atoms. Configuration-interaction relativistic-many-body-perturbation theory (CI-RMBPT) has been successful in predicting atomic energies, matrix elements between discrete states, and other properties, which is quite promising, but it has not been applied to photoionization problems owing to extra complications arising from continuum states. In this paper a method that will allow the conversion of discrete CI-(R)MPBT oscillator strengths (OS) to photoionization cross sections with minimal modifications of the codes is introduced and CI-RMBPT cross sections of Ne, Ar, Kr, and Xe are calculated. A consistent agreementmore » with experiment is found. RMBPT corrections are particularly significant for Ar, Kr, and Xe and improve agreement with experimental results compared to the particle-hole CI method. As a result, the demonstrated conversion method can be applied to CI-RMBPT photoionization calculations for a large number of multivalence atoms and ions.« less

  13. Precise and absolute measurements of complex third-order optical susceptibility

    NASA Astrophysics Data System (ADS)

    Santran, Stephane; Canioni, Lionel; Cardinal, Thierry; Fargin, Evelyne; Le Flem, Gilles; Rouyer, Claude; Sarger, Laurent

    2000-11-01

    We present precise and absolute measurements of full complex third order optical susceptibility on different fused silica and original glasses composed of tellurium, titanium, niobium erbium. These materials are designed to be the key point for applications ranging form high power laser systems to optoelectronics, their nonlinear index of refraction is a major property and thus must be accurately known. Due to the accuracy and sensitivity of our technique, we have been able to find a large dispersion (more than 30%) of the non linear index of fused silica glasses as a function of their processing mode. On the other hand, measurements on tellurium glasses have shown very strong nonlinearities (40 times higher than fused silica), to be linked to the configurations of their cations and anions. Although the titanium and niobium glasses are less nonlinear, they can be promising matrices for addition of luminescent entities like erbium leading to very interesting laser amplification materials. The experimental set-up is a collinear pump-probe (orthogonally polarized) experiment using transient absorption technique. It is built with around a 100 femtosecond laser oscillator. A fast oscillating delay between the pump and the probe allows us to measure the electronic nonlinearity in quasi real-time. This experiment has the following specifications: an absolute measurement accuracy below 10% mainly due to the laser parameters characterization, a relative measurement accuracy of 1% and a resolution less than 5.10-24m2/V2(50 times less than fused silica).

  14. Imbedded Nanocrystals of CsPbBr3 in Cs4 PbBr6 : Kinetics, Enhanced Oscillator Strength, and Application in Light-Emitting Diodes.

    PubMed

    Xu, Junwei; Huang, Wenxiao; Li, Peiyun; Onken, Drew R; Dun, Chaochao; Guo, Yang; Ucer, Kamil B; Lu, Chang; Wang, Hongzhi; Geyer, Scott M; Williams, Richard T; Carroll, David L

    2017-11-01

    Solution-grown films of CsPbBr 3 nanocrystals imbedded in Cs 4 PbBr 6 are incorporated as the recombination layer in light-emitting diode (LED) structures. The kinetics at high carrier density of pure (extended) CsPbBr 3 and the nanoinclusion composite are measured and analyzed, indicating second-order kinetics in extended and mainly first-order kinetics in the confined CsPbBr 3 , respectively. Analysis of absorption strength of this all-perovskite, all-inorganic imbedded nanocrystal composite relative to pure CsPbBr 3 indicates enhanced oscillator strength consistent with earlier published attribution of the sub-nanosecond exciton radiative lifetime in nanoprecipitates of CsPbBr 3 in melt-grown CsBr host crystals and CsPbBr 3 evaporated films. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Gβ Regulates Coupling between Actin Oscillators for Cell Polarity and Directional Migration

    PubMed Central

    Cai, Huaqing; Sun, Yaohui; Huang, Chuan-Hsiang; Freyre, Mariel; Zhao, Min; Devreotes, Peter N.; Weiner, Orion D.

    2016-01-01

    For directional movement, eukaryotic cells depend on the proper organization of their actin cytoskeleton. This engine of motility is made up of highly dynamic nonequilibrium actin structures such as flashes, oscillations, and traveling waves. In Dictyostelium, oscillatory actin foci interact with signals such as Ras and phosphatidylinositol 3,4,5-trisphosphate (PIP3) to form protrusions. However, how signaling cues tame actin dynamics to produce a pseudopod and guide cellular motility is a critical open question in eukaryotic chemotaxis. Here, we demonstrate that the strength of coupling between individual actin oscillators controls cell polarization and directional movement. We implement an inducible sequestration system to inactivate the heterotrimeric G protein subunit Gβ and find that this acute perturbation triggers persistent, high-amplitude cortical oscillations of F-actin. Actin oscillators that are normally weakly coupled to one another in wild-type cells become strongly synchronized following acute inactivation of Gβ. This global coupling impairs sensing of internal cues during spontaneous polarization and sensing of external cues during directional motility. A simple mathematical model of coupled actin oscillators reveals the importance of appropriate coupling strength for chemotaxis: moderate coupling can increase sensitivity to noisy inputs. Taken together, our data suggest that Gβ regulates the strength of coupling between actin oscillators for efficient polarity and directional migration. As these observations are only possible following acute inhibition of Gβ and are masked by slow compensation in genetic knockouts, our work also shows that acute loss-of-function approaches can complement and extend the reach of classical genetics in Dictyostelium and likely other systems as well. PMID:26890004

  16. Perturbation theory for arbitrary coupling strength?

    NASA Astrophysics Data System (ADS)

    Mahapatra, Bimal P.; Pradhan, Noubihary

    2018-03-01

    We present a new formulation of perturbation theory for quantum systems, designated here as: “mean field perturbation theory” (MFPT), which is free from power-series-expansion in any physical parameter, including the coupling strength. Its application is thereby extended to deal with interactions of arbitrary strength and to compute system-properties having non-analytic dependence on the coupling, thus overcoming the primary limitations of the “standard formulation of perturbation theory” (SFPT). MFPT is defined by developing perturbation about a chosen input Hamiltonian, which is exactly solvable but which acquires the nonlinearity and the analytic structure (in the coupling strength) of the original interaction through a self-consistent, feedback mechanism. We demonstrate Borel-summability of MFPT for the case of the quartic- and sextic-anharmonic oscillators and the quartic double-well oscillator (QDWO) by obtaining uniformly accurate results for the ground state of the above systems for arbitrary physical values of the coupling strength. The results obtained for the QDWO may be of particular significance since “renormalon”-free, unambiguous results are achieved for its spectrum in contrast to the well-known failure of SFPT in this case.

  17. A Resonantly Excited Disk-Oscillation Model of High-Frequency QPOs of Microquasars

    NASA Astrophysics Data System (ADS)

    Kato, Shoji

    2012-12-01

    A possible model of twin high-frequency QPOs (HF QPOs) of microquasars is examined. The disk is assumed to have global magnetic fields and to be deformed with a two-armed pattern. In this deformed disk, a set of a two-armed (m = 2) vertical p-mode oscillation and an axisymmetric (m = 0) g-mode oscillation is considered. They resonantly interact through the disk deformation when their frequencies are the same. This resonant interaction amplifies the set of the above oscillations in the case where these two oscillations have wave energies of opposite signs. These oscillations are assumed to be excited most efficiently in the case where the radial group velocities of these two waves vanish at the same place. The above set of oscillations is not unique, depending on the node number n, of oscillations in the vertical direction. We consider that the basic two sets of oscillations correspond to the twin QPOs. The frequencies of these oscillations depend on the disk parameters, such as the strength of the magnetic fields. For observational mass ranges of GRS 1915+ 105, GRO J1655-40, XTE J1550-564, and HEAO H1743-322, the spins of these sources are estimated. High spins of these sources can be described if the disks have weak poloidal magnetic fields as well as toroidal magnetic fields of moderate strength. In this model the 3:2 frequency ratio of high-frequency QPOs is not related to their excitation, but occurs by chance.

  18. Collective signaling behavior in a networked-oscillator model

    NASA Astrophysics Data System (ADS)

    Liu, Z.-H.; Hui, P. M.

    2007-09-01

    We propose and study the collective behavior of a model of networked signaling objects that incorporates several ingredients of real-life systems. These ingredients include spatial inhomogeneity with grouping of signaling objects, signal attenuation with distance, and delayed and impulsive coupling between non-identical signaling objects. Depending on the coupling strength and/or time-delay effect, the model exhibits completely, partially, and locally collective signaling behavior. In particular, a correlated signaling (CS) behavior is observed in which there exist time durations when nearly a constant fraction of oscillators in the system are in the signaling state. These time durations are much longer than the duration of a spike when a single oscillator signals, and they are separated by regular intervals in which nearly all oscillators are silent. Such CS behavior is similar to that observed in biological systems such as fireflies, cicadas, crickets, and frogs. The robustness of the CS behavior against noise is also studied. It is found that properly adjusting the coupling strength and noise level could enhance the correlated behavior.

  19. Patterns of Hand Grip Strength and Detection of Strength Loss in Patients Undergoing Bone Marrow Transplantation: A Feasibility Study.

    PubMed

    Sayre, Cindy A; Belza, Basia; Shannon Dorcy, Kathleen; Phelan, Elizabeth; Whitney, JoAnne D

    2017-09-01

    To determine the feasibility of measuring hand grip strength (HGS) daily in a population of recipients of bone marrow transplantation (BMT), to describe changes in strength measured by HGS, and to describe relationships between laboratory values (hematocrit, hemoglobin, and absolute neutrophil count) and HGS.
. Prospective, longitudinal, repeated measures, within subject.
. Inpatient units at the University of Washington Medical Center in Seattle.
. 33 patients admitted in preparation for BMT or for complications from BMT.
. HGS measured on admission and daily.
. HGS, absolute neutrophil count, hemoglobin, and hematocrit.
. Participants found HGS testing to be relatively easy. Average time to complete testing was 7.2 minutes (SD = 1.95). Nineteen experienced 20% or greater decline in HGS during hospitalization, with nine experiencing decline during the conditioning phase. Age, gender, and hemoglobin correlated with HGS. Strength loss was more likely in those undergoing allogeneic compared to autologous BMT.
. A majority of patients experienced strength decline during BMT, with a subgroup declining during conditioning. A positive relationship existed between HGS and hemoglobin and hematocrit in participants admitted for conditioning for BMT.
. Weakness increases risk for falls. Patients may experience as much as 50% strength loss during the course of hospitalization for BMT. Strength loss occurs in the conditioning phase for some patients.

  20. Winner-take-all in a phase oscillator system with adaptation.

    PubMed

    Burylko, Oleksandr; Kazanovich, Yakov; Borisyuk, Roman

    2018-01-11

    We consider a system of generalized phase oscillators with a central element and radial connections. In contrast to conventional phase oscillators of the Kuramoto type, the dynamic variables in our system include not only the phase of each oscillator but also the natural frequency of the central oscillator, and the connection strengths from the peripheral oscillators to the central oscillator. With appropriate parameter values the system demonstrates winner-take-all behavior in terms of the competition between peripheral oscillators for the synchronization with the central oscillator. Conditions for the winner-take-all regime are derived for stationary and non-stationary types of system dynamics. Bifurcation analysis of the transition from stationary to non-stationary winner-take-all dynamics is presented. A new bifurcation type called a Saddle Node on Invariant Torus (SNIT) bifurcation was observed and is described in detail. Computer simulations of the system allow an optimal choice of parameters for winner-take-all implementation.

  1. Axion induced oscillating electric dipole moments

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

    Hill, Christopher T.

    In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency m a and strength ~ 10-32 e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.

  2. Self-organisation of random oscillators with Lévy stable distributions

    NASA Astrophysics Data System (ADS)

    Moradi, Sara; Anderson, Johan

    2017-08-01

    A novel possibility of self-organized behaviour of stochastically driven oscillators is presented. It is shown that synchronization by Lévy stable processes is significantly more efficient than that by oscillators with Gaussian statistics. The impact of outlier events from the tail of the distribution function was examined by artificially introducing a few additional oscillators with very strong coupling strengths and it is found that remarkably even one such rare and extreme event may govern the long term behaviour of the coupled system. In addition to the multiplicative noise component, we have investigated the impact of an external additive Lévy distributed noise component on the synchronisation properties of the oscillators.

  3. Fine Structure of Beta Decay Strength Function and Anisotropy of Isovector Nuclear Dencity Component Oscillations in Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Izosimov, I. N.; Solnyshkin, A. A.; Khushvaktov, J. H.; Vaganov, Yu. A.

    2018-05-01

    The experimental measurement data on the fine structure of beta-decay strength function S β( E) in spherical, transitional, and deformed nuclei are analyzed. Modern high-resolution nuclear spectroscopy methods made it possible to identify the splitting of peaks in S β( E) for deformed nuclei. By analogy with splitting of the peak of E1 giant dipole resonance (GDR) in deformed nuclei, the peaks in S β( E) are split into two components from the axial nuclear deformation. In this report, the fine structure of S β( E) is discussed. Splitting of the peaks connected with the oscillations of neutrons against protons (E1GDR), of proton holes against neutrons (peaks in S β( E) of β+/ EC-decay), and of protons against neutron holes (peaks in S β( E) of β--decay) is discussed.

  4. Stellar laboratories. VI. New Mo iv-vii oscillator strengths and the molybdenum abundance in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Demleitner, M.; Kruk, J. W.

    2016-03-01

    Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To identify molybdenum lines in the ultraviolet (UV) spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and, to determine their photospheric Mo abundances, reliable Mo iv-vii oscillator strengths are used. Methods: We newly calculated Mo iv-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Mo lines exhibited in high-resolution and high S/N UV observations of RE 0503-289. Results: We identified 12 Mo v and 9 Mo vi lines in the UV spectrum of RE 0503-289 and measured a photospheric Mo abundance of 1.2-3.0 × 10-4 (mass fraction, 22 500-56 400 times the solar abundance). In addition, from the As v and Sn iv resonance lines, we measured mass fractions of arsenic (0.5-1.3 × 10-5, about 300-1200 times solar) and tin (1.3-3.2 × 10-4, about 14 300-35 200 times solar). For G191-B2B, upper limits were determined for the abundances of Mo (5.3 × 10-7, 100 times solar) and, in addition, for Kr (1.1 × 10-6, 10 times solar) and Xe (1.7 × 10-7, 10 times solar). The arsenic abundance was determined (2.3-5.9 × 10-7, about 21-53 times solar). A new, registered German Astrophysical Virtual Observatory (GAVO) service, TOSS, has been constructed to provide weighted oscillator strengths and transition probabilities. Conclusions: Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. Observed Mo v-vi line profiles in the UV spectrum of the white dwarf RE 0503-289 were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed the photospheric Mo

  5. Adaptive oscillator networks with conserved overall coupling: Sequential firing and near-synchronized states

    NASA Astrophysics Data System (ADS)

    Picallo, Clara B.; Riecke, Hermann

    2011-03-01

    Motivated by recent observations in neuronal systems we investigate all-to-all networks of nonidentical oscillators with adaptive coupling. The adaptation models spike-timing-dependent plasticity in which the sum of the weights of all incoming links is conserved. We find multiple phase-locked states that fall into two classes: near-synchronized states and splay states. Among the near-synchronized states are states that oscillate with a frequency that depends only very weakly on the coupling strength and is essentially given by the frequency of one of the oscillators, which is, however, neither the fastest nor the slowest oscillator. In sufficiently large networks the adaptive coupling is found to develop effective network topologies dominated by one or two loops. This results in a multitude of stable splay states, which differ in their firing sequences. With increasing coupling strength their frequency increases linearly and the oscillators become less synchronized. The essential features of the two classes of states are captured analytically in perturbation analyses of the extended Kuramoto model used in the simulations.

  6. Time Delay Effect in a Living Coupled Oscillator System with the Plasmodium of Physarum polycephalum

    NASA Astrophysics Data System (ADS)

    Takamatsu, Atsuko; Fujii, Teruo; Endo, Isao

    2000-08-01

    A living coupled oscillator system was constructed by a cell patterning method with a plasmodial slime mold, in which parameters such as coupling strength and distance between the oscillators can be systematically controlled. Rich oscillation phenomena between the two-coupled oscillators, namely, desynchronizing and antiphase/in-phase synchronization were observed according to these parameters. Both experimental and theoretical approaches showed that these phenomena are closely related to the time delay effect in interactions between the oscillators.

  7. Input-dependent frequency modulation of cortical gamma oscillations shapes spatial synchronization and enables phase coding.

    PubMed

    Lowet, Eric; Roberts, Mark; Hadjipapas, Avgis; Peter, Alina; van der Eerden, Jan; De Weerd, Peter

    2015-02-01

    Fine-scale temporal organization of cortical activity in the gamma range (∼25-80Hz) may play a significant role in information processing, for example by neural grouping ('binding') and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency codes

  8. Input-Dependent Frequency Modulation of Cortical Gamma Oscillations Shapes Spatial Synchronization and Enables Phase Coding

    PubMed Central

    Lowet, Eric; Roberts, Mark; Hadjipapas, Avgis; Peter, Alina; van der Eerden, Jan; De Weerd, Peter

    2015-01-01

    Fine-scale temporal organization of cortical activity in the gamma range (∼25–80Hz) may play a significant role in information processing, for example by neural grouping (‘binding’) and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency

  9. Lifetimes and Oscillator Strengths for Ultraviolet Transitions in P II, Cl II and Cl III

    NASA Technical Reports Server (NTRS)

    Cheng, S.; Federman, S. R.; Schectman, R. M.; Brown, M.; Irving, R. E.; Fritts, M. C.; Gibson, N. D.

    2006-01-01

    Oscillator strengths for transitions in P II, Cl II and Cl III are derived from lifetimes and branching factions measured with beam-foil techniques. The focus is on the multiplets with a prominent interstellar line at 1153 A in P II which is seen in spectra of hot stars, and the lines at 1071 A in Cl II and 1011 A in Cl III whose lines are seen in spectra of diffuse interstellar clouds and the Io torus acquired with the Far Ultraviolet Spectroscopic Explorer. These data represent the first complete set of experimental f-values for the lines in the multiplets. Our results for P II (lambda)1153 agree well with Curtis semi-empirical predictions, as well as the large scale computations by Hibbert and by Tayal. The data for Cl II (lambda)1071 also agree very well with the most recent theoretical effort and with Morton s newest recommendations. For Cl III, however, our f-values are significantly larger than those given by Morton; instead, they are more consistent with recent large-scale theoretical calculations. Extensive tests provide confirmation that LS coupling rules apply to the transitions for the multiplets in Cl II and Cl III.

  10. Differential Resonant Ring YIG Tuned Oscillator

    NASA Technical Reports Server (NTRS)

    Parrott, Ronald A.

    2010-01-01

    A differential SiGe oscillator circuit uses a resonant ring-oscillator topology in order to electronically tune the oscillator over multi-octave bandwidths. The oscillator s tuning is extremely linear, because the oscillator s frequency depends on the magnetic tuning of a YIG sphere, whose resonant frequency is equal to a fundamental constant times the DC magnetic field. This extremely simple circuit topology uses two coupling loops connecting a differential pair of SiGe bipolar transistors into a feedback configuration using a YIG tuned filter creating a closed-loop ring oscillator. SiGe device technology is used for this oscillator in order to keep the transistor s 1/f noise to an absolute minimum in order to achieve minimum RF phase noise. The single-end resonant ring oscillator currently has an advantage in fewer parts, but when the oscillation frequency is greater than 16 GHz, the package s parasitic behavior couples energy to the sphere and causes holes and poor phase noise performance. This is because the coupling to the YIG is extremely low, so that the oscillator operates at near the unloaded Q. With the differential resonant ring oscillator, the oscillation currents are just in the YIG coupling mechanisms. The phase noise is even better, and the physical size can be reduced to permit monolithic microwave integrated circuit oscillators. This invention is a YIG tuned oscillator circuit making use of a differential topology to simultaneously achieve an extremely broadband electronic tuning range and ultra-low phase noise. As a natural result of its differential circuit topology, all reactive elements, such as tuning stubs, which limit tuning bandwidth by contributing excessive open loop phase shift, have been eliminated. The differential oscillator s open-loop phase shift is associated with completely non-dispersive circuit elements such as the physical angle of the coupling loops, a differential loop crossover, and the high-frequency phase shift of the n

  11. Search for n -n ¯ oscillation in Super-Kamiokande

    NASA Astrophysics Data System (ADS)

    Abe, K.; Hayato, Y.; Iida, T.; Ishihara, K.; Kameda, J.; Koshio, Y.; Minamino, A.; Mitsuda, C.; Miura, M.; Moriyama, S.; Nakahata, M.; Obayashi, Y.; Ogawa, H.; Sekiya, H.; Shiozawa, M.; Suzuki, Y.; Takeda, A.; Takeuchi, Y.; Ueshima, K.; Watanabe, H.; Higuchi, I.; Ishihara, C.; Ishitsuka, M.; Kajita, T.; Kaneyuki, K.; Mitsuka, G.; Nakayama, S.; Nishino, H.; Okumura, K.; Saji, C.; Takenaga, Y.; Clark, S.; Desai, S.; Dufour, F.; Herfurth, A.; Kearns, E.; Likhoded, S.; Litos, M.; Raaf, J. L.; Stone, J. L.; Sulak, L. R.; Wang, W.; Goldhaber, M.; Casper, D.; Cravens, J. P.; Dunmore, J.; Griskevich, J.; Kropp, W. R.; Liu, D. W.; Mine, S.; Regis, C.; Smy, M. B.; Sobel, H. W.; Vagins, M. R.; Ganezer, K. S.; Hartfiel, B.; Hill, J.; Keig, W. E.; Jang, J. S.; Jeoung, I. S.; Kim, J. Y.; Lim, I. T.; Scholberg, K.; Tanimoto, N.; Walter, C. W.; Wendell, R.; Ellsworth, R. W.; Tasaka, S.; Guillian, G.; Learned, J. G.; Matsuno, S.; Messier, M. D.; Ichikawa, A. K.; Ishida, T.; Ishii, T.; Iwashita, T.; Kobayashi, T.; Nakadaira, T.; Nakamura, K.; Nishikawa, K.; Nitta, K.; Oyama, Y.; Suzuki, A. T.; Hasegawa, M.; Maesaka, H.; Nakaya, T.; Sasaki, T.; Sato, H.; Tanaka, H.; Yamamoto, S.; Yokoyama, M.; Haines, T. J.; Dazeley, S.; Hatakeyama, S.; Svoboda, R.; Sullivan, G. W.; Gran, R.; Habig, A.; Fukuda, Y.; Itow, Y.; Koike, T.; Jung, C. K.; Kato, T.; Kobayashi, K.; McGrew, C.; Sarrat, A.; Terri, R.; Yanagisawa, C.; Tamura, N.; Ikeda, M.; Sakuda, M.; Kuno, Y.; Yoshida, M.; Kim, S. B.; Yang, B. S.; Ishizuka, T.; Okazawa, H.; Choi, Y.; Seo, H. K.; Gando, Y.; Hasegawa, T.; Inoue, K.; Ishii, H.; Nishijima, K.; Ishino, H.; Watanabe, Y.; Koshiba, M.; Totsuka, Y.; Chen, S.; Deng, Z.; Liu, Y.; Kielczewska, D.; Berns, H. G.; Shiraishi, K. K.; Thrane, E.; Washburn, K.; Wilkes, R. J.; Super-Kamiokande Collaboration

    2015-04-01

    A search for neutron-antineutron (n -n ¯) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or 2.45 ×1034 neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for n -n ¯ oscillation was found; the lower limit of the lifetime for neutrons bound in 16O, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9 ×1032 years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7 ×108 s using a theoretical value of the nuclear suppression factor of 0.517 ×1023 s-1 and its uncertainty.

  12. Neutrino-oscillation search with cosmic-ray neutrinos

    NASA Astrophysics Data System (ADS)

    Ayres, D. S.; Cortez, B.; Gaisser, T. K.; Mann, A. K.; Shrock, R. E.; Sulak, L. R.

    1984-03-01

    A sensitive search for neutrino oscillations involving νe, νμ, and ντ may be provided by measurements of the ratio of the total interaction rates of upward- and downward-going cosmic-ray neutrinos within a massive (~10 kton) detector. Assuming mixing between all pairs of νe, νμ, and ντ, the experiment is capable of observing time-averaged probabilities t and t of magnitude set by mixing strengths corresponding to, e.g., the d- to s-quark mixing strength, and of reaching the limit Δm2ij≡|mi2-mj2|~10-4 eV2, where mi, and mj are neutrino mass eigenstates, and Peτ and Pμτ are the probabilities for νe and νμ, respectively, to oscillate into ντ after traversing a distance L~ diameter of the Earth. Possible ambiguities may be resolved through comparison of the ratios NeNμ for the upward- and downward-going neutrinos.

  13. Anharmonic Oscillations of a Spring-Magnet System inside a Magnetic Coil

    ERIC Educational Resources Information Center

    Ladera, Celso L.; Donoso, Guillermo

    2012-01-01

    We consider the nonlinear oscillations of a simple spring-magnet system that oscillates in the magnetic field of an inductive coil excited with a dc current. Using the relations for the interaction of a coil and a magnet we obtain the motion equation of the system. The relative strengths of the terms of this equation can be adjusted easily by…

  14. Oscillator strengths for ionized iron and manganese

    NASA Technical Reports Server (NTRS)

    De Boer, K. S.; Pottasch, S. R.; Morton, D. C.; York, D. G.

    1974-01-01

    The observed strengths of interstellar absorption lines of Fe II and Mn II in the spectra of alpha Vir, beta Cen, pi Sco, and zeta Oph along with laboratory f values of some of these lines between 2343 and 2606 A have been used to determine curves of growth for these ions and the f-values of ten lines of Fe II and three lines of Mn II between 1055 and 1261 A. The Fe and Mn abundances are derived.

  15. Basin stability measure of different steady states in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Rakshit, Sarbendu; Bera, Bidesh K.; Majhi, Soumen; Hens, Chittaranjan; Ghosh, Dibakar

    2017-04-01

    In this report, we investigate the stabilization of saddle fixed points in coupled oscillators where individual oscillators exhibit the saddle fixed points. The coupled oscillators may have two structurally different types of suppressed states, namely amplitude death and oscillation death. The stabilization of saddle equilibrium point refers to the amplitude death state where oscillations are ceased and all the oscillators converge to the single stable steady state via inverse pitchfork bifurcation. Due to multistability features of oscillation death states, linear stability theory fails to analyze the stability of such states analytically, so we quantify all the states by basin stability measurement which is an universal nonlocal nonlinear concept and it interplays with the volume of basins of attractions. We also observe multi-clustered oscillation death states in a random network and measure them using basin stability framework. To explore such phenomena we choose a network of coupled Duffing-Holmes and Lorenz oscillators which are interacting through mean-field coupling. We investigate how basin stability for different steady states depends on mean-field density and coupling strength. We also analytically derive stability conditions for different steady states and confirm by rigorous bifurcation analysis.

  16. Synchronisation hubs in the visual cortex may arise from strong rhythmic inhibition during gamma oscillations.

    PubMed

    Folias, Stefanos E; Yu, Shan; Snyder, Abigail; Nikolić, Danko; Rubin, Jonathan E

    2013-09-01

    Neurons in the visual cortex exhibit heterogeneity in feature selectivity and the tendency to generate action potentials synchronously with other nearby neurons. By examining visual responses from cat area 17 we found that, during gamma oscillations, there was a positive correlation between each unit's sharpness of orientation tuning, strength of oscillations, and propensity towards synchronisation with other units. Using a computational model, we demonstrated that heterogeneity in the strength of rhythmic inhibitory inputs can account for the correlations between these three properties. Neurons subject to strong inhibition tend to oscillate strongly in response to both optimal and suboptimal stimuli and synchronise promiscuously with other neurons, even if they have different orientation preferences. Moreover, these strongly inhibited neurons can exhibit sharp orientation selectivity provided that the inhibition they receive is broadly tuned relative to their excitatory inputs. These results predict that the strength and orientation tuning of synaptic inhibition are heterogeneous across area 17 neurons, which could have important implications for these neurons' sensory processing capabilities. Furthermore, although our experimental recordings were conducted in the visual cortex, our model and simulation results can apply more generally to any brain region with analogous neuron types in which heterogeneity in the strength of rhythmic inhibition can arise during gamma oscillations. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  17. Circuit oscillations in odor perception and memory.

    PubMed

    Kay, Leslie M

    2014-01-01

    Olfactory system neural oscillations as seen in the local field potential have been studied for many decades. Recent research has shown that there is a functional role for the most studied gamma oscillations (40-100Hz in rats and mice, and 20Hz in insects), without which fine odor discrimination is poor. When these oscillations are increased artificially, fine discrimination is increased, and when rats learn difficult and highly overlapping odor discriminations, gamma is increased in power. Because of the depth of study on this oscillation, it is possible to point to specific changes in neural firing patterns as represented by the increase in gamma oscillation amplitude. However, we know far less about the mechanisms governing beta oscillations (15-30Hz in rats and mice), which are best associated with associative learning of responses to odor stimuli. These oscillations engage every part of the olfactory system that has so far been tested, plus the hippocampus, and the beta oscillation frequency band is the one that is most reliably coherent with other regions during odor processing. Respiratory oscillations overlapping with the theta frequency band (2-12Hz) are associated with odor sniffing and normal breathing in rats. They also show coupling in some circumstances between olfactory areas and rare coupling between the hippocampus and olfactory bulb. The latter occur in specific learning conditions in which coherence strength is negatively or positively correlated with performance, depending on the task. There is still much to learn about the role of neural oscillations in learning and memory, but techniques that have been brought to bear on gamma oscillations (current source density, computational modeling, slice physiology, behavioral studies) should deliver much needed knowledge of these events. © 2014 Elsevier B.V. All rights reserved.

  18. Controllability in tunable chains of coupled harmonic oscillators

    NASA Astrophysics Data System (ADS)

    Buchmann, L. F.; Mølmer, K.; Petrosyan, D.

    2018-04-01

    We prove that temporal control of the strengths of springs connecting N harmonic oscillators in a chain provides complete access to all Gaussian states of N -1 collective modes. The proof relies on the construction of a suitable basis of cradle modes for the system. An iterative algorithm to reach any desired Gaussian state requires at most 3 N (N -1 )/2 operations. We illustrate this capability by engineering squeezed pseudo-phonon states—highly nonlocal, strongly correlated states that may result from various nonlinear processes. Tunable chains of coupled harmonic oscillators can be implemented by a number of current state-of-the-art experimental platforms, including cold atoms in lattice potentials, arrays of mechanical micro-oscillators, and coupled optical waveguides.

  19. THE EFFECTS OF LINE-OF-SIGHT INTEGRATION ON MULTISTRAND CORONAL LOOP OSCILLATIONS

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

    De Moortel, I.; Pascoe, D. J., E-mail: ineke@mcs.st-and.ac.uk

    2012-02-10

    Observations have shown that transverse oscillations are present in a multitude of coronal structures. It is generally assumed that these oscillations are driven by (sub)surface footpoint motions. Using fully three-dimensional MHD simulations, we show that these footpoint perturbations generate propagating kink (Alfvenic) modes which couple very efficiently into (azimuthal) Alfven waves. Using an ensemble of randomly distributed loops, driven by footpoint motions with random periods and directions, we compare the absolute energy in the numerical domain with the energy that is 'visible' when integrating along the line of sight (LOS). We show that the kinetic energy derived from the LOSmore » Doppler velocities is only a small fraction of the actual energy provided by the footpoint motions. Additionally, the superposition of loop structures along the LOS makes it nearly impossible to identify which structure the observed oscillations are actually associated with and could impact the identification of the mode of oscillation.« less

  20. Order parameter description of walk-off effect on pattern selection in degenerate optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Taki, Majid; San Miguel, Maxi; Santagiustina, Marco

    2000-02-01

    Degenerate optical parametric oscillators can exhibit both uniformly translating fronts and nonuniformly translating envelope fronts under the walk-off effect. The nonlinear dynamics near threshold is shown to be described by a real convective Swift-Hohenberg equation, which provides the main characteristics of the walk-off effect on pattern selection. The predictions of the selected wave vector and the absolute instability threshold are in very good quantitative agreement with numerical solutions found from the equations describing the optical parametric oscillator.

  1. Accurate atomic data for xenon: energy levels, oscillator strengths, and electron collision cross sections

    NASA Astrophysics Data System (ADS)

    Bartschat, Klaus; Zatsarinny, Oleg

    2009-10-01

    We have applied our recently developed fully relativistic Dirac B-spline R-matrix (DBSR) code [1] to calculate the atomic structure (energy levels and oscillator strengths) as well as electron scattering from xenon atoms. Results from a 31-state close-coupling model for the excitation function of the metastable (5p^5 6s) J=0,2 states show excellent agreement with experiment [2], thereby presenting a significant improvement over the most sophisticated previous Breit-Pauli calculations [3,4]. The same model is currently being used to calculate electron-impact excitation from the metastable J=2 state. The results will be compared with recent experimental data [5] and predictions from other theoretical models [6,7]. Our dataset is an excellent basis for modeling plasma discharges containing xenon.[0pt] [1] O. Zatsarinny and K. Bartschat, Phys. Rev. A 77 (2008) 062701.[0pt] [2] S. J. Buckman et al., J. Phys. B 16 (1983) 4219.[0pt] [3] A. N. Grum-Grzhimailo and K. Bartschat, J. Phys. B 35 (2002) 3479.[0pt] [4] M. Allan et al., Phys. Rev. A 74 (2006) 030701(R).[0pt] [5] R. O. Jung et al., Phys. Rev. A 72 (2005) 022723.[0pt] [6] R. Srivastava et al., Phys. Rev. A 74 (2006) 012715.[0pt] [7] J. Jiang et al., J. Phys. B 41 (2008) 245204.

  2. Seizure Dynamics of Coupled Oscillators with Epileptor Field Model

    NASA Astrophysics Data System (ADS)

    Zhang, Honghui; Xiao, Pengcheng

    The focus of this paper is to investigate the dynamics of seizure activities by using the Epileptor coupled model. Based on the coexistence of seizure-like event (SLE), refractory status epilepticus (RSE), depolarization block (DB), and normal state, we first study the dynamical behaviors of two coupled oscillators in different activity states with Epileptor model by linking them with slow permittivity coupling. Our research has found that when one oscillator in normal states is coupled with any oscillator in SLE, RSE or DB states, these two oscillators can both evolve into SLE states under appropriate coupling strength. And then these two SLE oscillators can perform epileptiform synchronization or epileptiform anti-synchronization. Meanwhile, SLE can be depressed when considering the fast electrical or chemical coupling in Epileptor model. Additionally, a two-dimensional reduced model is also given to show the effect of coupling number on seizures. Those results can help to understand the dynamical mechanism of the initiation, maintenance, propagation and termination of seizures in focal epilepsy.

  3. Effective Collision Strengths for Fine-structure Transitions in Si VII

    NASA Astrophysics Data System (ADS)

    Sossah, A. M.; Tayal, S. S.

    2014-05-01

    The effective collision strengths for electron-impact excitation of fine-structure transitions in Si VII are calculated as a function of electron temperature in the range 5000-2,000,000 K. The B-spline Breit-Pauli R-matrix method has been used to calculate collision strengths by electron impact. The target wave functions have been obtained using the multi-configuration Hartree-Fock method with term-dependent non-orthogonal orbitals. The 92 fine-structure levels belonging to the 46 LS states of 2s 22p 4, 2s2p 5, 2p 6, 2s 22p 33s, 2s 22p 33p, 2s 22p 33d, and 2s2p 43s configurations are included in our calculations of oscillator strengths and collision strengths. There are 4186 possible fine-structure allowed and forbidden transitions among the 92 levels. The present excitation energies, oscillator strengths, and collision strengths have been compared with previous theoretical results and available experimental data. Generally, a good agreement is found with the 6 LS-state close-coupling approximation results of Butler & Zeippen and the 44 LS-state distorted wave calculation of Bhatia & Landi.

  4. Statistics of equivalent width data and new oscillator strengths for Si II, Fe II, and Mn II. [in interstellar medium

    NASA Technical Reports Server (NTRS)

    Van Buren, Dave

    1986-01-01

    Equivalent width data from Copernicus and IUE appear to have an exponential, rather than a Gaussian distribution of errors. This is probably because there is one dominant source of error: the assignment of the background continuum shape. The maximum likelihood method of parameter estimation is presented for the case of exponential statistics, in enough generality for application to many problems. The method is applied to global fitting of Si II, Fe II, and Mn II oscillator strengths and interstellar gas parameters along many lines of sight. The new values agree in general with previous determinations but are usually much more tightly constrained. Finally, it is shown that care must be taken in deriving acceptable regions of parameter space because the probability contours are not generally ellipses whose axes are parallel to the coordinate axes.

  5. Using coronal seismology to estimate the magnetic field strength in a realistic coronal model

    NASA Astrophysics Data System (ADS)

    Chen, F.; Peter, H.

    2015-09-01

    Aims: Coronal seismology is used extensively to estimate properties of the corona, e.g. the coronal magnetic field strength is derived from oscillations observed in coronal loops. We present a three-dimensional coronal simulation, including a realistic energy balance in which we observe oscillations of a loop in synthesised coronal emission. We use these results to test the inversions based on coronal seismology. Methods: From the simulation of the corona above an active region, we synthesise extreme ultraviolet emission from the model corona. From this, we derive maps of line intensity and Doppler shift providing synthetic data in the same format as obtained from observations. We fit the (Doppler) oscillation of the loop in the same fashion as done for observations to derive the oscillation period and damping time. Results: The loop oscillation seen in our model is similar to imaging and spectroscopic observations of the Sun. The velocity disturbance of the kink oscillation shows an oscillation period of 52.5 s and a damping time of 125 s, which are both consistent with the ranges of periods and damping times found in observations. Using standard coronal seismology techniques, we find an average magnetic field strength of Bkink = 79 G for our loop in the simulation, while in the loop the field strength drops from roughly 300 G at the coronal base to 50 G at the apex. Using the data from our simulation, we can infer what the average magnetic field derived from coronal seismology actually means. It is close to the magnetic field strength in a constant cross-section flux tube, which would give the same wave travel time through the loop. Conclusions: Our model produced a realistic looking loop-dominated corona, and provides realistic information on the oscillation properties that can be used to calibrate and better understand the result from coronal seismology. A movie associated with Fig. 1 is available in electronic form at http://www.aanda.org

  6. Quest for absolute zero in the presence of external noise.

    PubMed

    Torrontegui, E; Kosloff, R

    2013-09-01

    A reciprocating quantum refrigerator is analyzed with the intention to study the limitations imposed by external noise. In particular we focus on the behavior of the refrigerator when it approaches the absolute zero. The cooling cycle is based on the Otto cycle with a working medium constituted by an ensemble of noninteracting harmonic oscillators. The compression and expansion segments are generated by changing an external parameter in the Hamiltonian. In this case the force constant of the harmonic oscillators mω^{2} is modified from an initial to a final value. As a result, the kinetic and potential energy of the system do not commute causing frictional losses. By proper choice of scheduling function ω(t) frictionless solutions can be obtained in the noiseless case. We examine the performance of a refrigerator subject to noise. By expanding from the adiabatic limit we find that the external noise, Gaussian phase, and amplitude noises reduce the amount of heat that can be extracted but nevertheless the zero temperature can be approached.

  7. FOREWORD: The 9th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS 9)

    NASA Astrophysics Data System (ADS)

    Wahlgren, Glenn M.; Wiese, Wolfgang L.; Beiersdorfer, Peter

    2008-07-01

    For the first time since its inaugural meeting in Lund in 1983, the triennial international conference on Atomic Spectroscopy and Oscillator Strengths for Astrophysical and Laboratory Plasmas (ASOS) returned to Lund, Sweden. Lund has been a home to atomic spectroscopy since the time of Janne Rydberg, and included the pioneering work in laboratory and solar spectroscopy of Bengt Edlén, who presented the initial ASOS talk in 1983. The ninth ASOS was hosted by the Lund Observatory and the Physics Department of Lund University during from 8 to 10 August 2007 and was attended by nearly 100 registrants. An encouraging sign for the field was the number of young researchers in attendance. This volume contains the submitted contributions from the poster presentations of the conference, and represents approximately forty percent of the presented posters. A complementary volume of Physica Scripta provides the written transactions of the ASOS9 invited presentations. With these two volumes the character of ASOS9 is more fully evident, and they serve as a review of the state of atomic spectroscopy for spectrum analysis and the determination of oscillator strengths and their applications. The goal of ASOS is to be a forum for atomic spectroscopy where both the providers and users of atomic data, which includes wavelengths, energy levels, lifetimes, oscillator strengths, and line shape parameters, can meet to discuss recent advances in experimental and theoretical techniques and their application to understanding the physical processes that are responsible for producing observed spectra. The applications mainly originate from the fields of astrophysics and plasma physics, the latter including fusion energy and lighting research. As a part of ASOS9 we were honored to celebrate the retirement of Professor Sveneric Johansson. At a special session on the spectroscopy of iron, which was conducted in his honor, he presented his insights into the Fe II term system and his most recent

  8. Absolute calorimetric calibration of low energy brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Stump, Kurt E.

    In the past decade there has been a dramatic increase in the use of permanent radioactive source implants in the treatment of prostate cancer. A small radioactive source encapsulated in a titanium shell is used in this type of treatment. The radioisotopes used are generally 125I or 103Pd. Both of these isotopes have relatively short half-lives, 59.4 days and 16.99 days, respectively, and have low-energy emissions and a low dose rate. These factors make these sources well suited for this application, but the calibration of these sources poses significant metrological challenges. The current standard calibration technique involves the measurement of ionization in air to determine the source air-kerma strength. While this has proved to be an improvement over previous techniques, the method has been shown to be metrologically impure and may not be the ideal means of calbrating these sources. Calorimetric methods have long been viewed to be the most fundamental means of determining source strength for a radiation source. This is because calorimetry provides a direct measurement of source energy. However, due to the low energy and low power of the sources described above, current calorimetric methods are inadequate. This thesis presents work oriented toward developing novel methods to provide direct and absolute measurements of source power for low-energy low dose rate brachytherapy sources. The method is the first use of an actively temperature-controlled radiation absorber using the electrical substitution method to determine total contained source power of these sources. The instrument described operates at cryogenic temperatures. The method employed provides a direct measurement of source power. The work presented here is focused upon building a metrological foundation upon which to establish power-based calibrations of clinical-strength sources. To that end instrument performance has been assessed for these source strengths. The intent is to establish the limits of

  9. Spatial Noise in Coupling Strength and Natural Frequency within a Pacemaker Network; Consequences for Development of Intestinal Motor Patterns According to a Weakly Coupled Phase Oscillator Model

    PubMed Central

    Parsons, Sean P.; Huizinga, Jan D.

    2016-01-01

    Pacemaker activities generated by networks of interstitial cells of Cajal (ICC), in conjunction with the enteric nervous system, orchestrate most motor patterns in the gastrointestinal tract. It was our objective to understand the role of network features of ICC associated with the myenteric plexus (ICC-MP) in the shaping of motor patterns of the small intestine. To that end, a model of weakly coupled oscillators (oscillators influence each other's phase but not amplitude) was created with most parameters derived from experimental data. The ICC network is a uniform two dimensional network coupled by gap junctions. All ICC generate pacemaker (slow wave) activity with a frequency gradient in mice from 50/min at the proximal end of the intestine to 40/min at the distal end. Key features of motor patterns, directly related to the underlying pacemaker activity, are frequency steps and dislocations. These were accurately mimicked by reduction of coupling strength at a point in the chain of oscillators. When coupling strength was expressed as a product of gap junction density and conductance, and gap junction density was varied randomly along the chain (i.e., spatial noise) with a long-tailed distribution, plateau steps occurred at pointsof low density. As gap junction conductance was decreased, the number of plateaus increased, mimicking the effect of the gap junction inhibitor carbenoxolone. When spatial noise was added to the natural interval gradient, as gap junction conductance decreased, the number of plateaus increased as before but in addition the phase waves frequently changed direction of apparent propagation, again mimicking the effect of carbenoxolone. In summary, key features of the motor patterns that are governed by pacemaker activity may be a direct consequence of biological noise, specifically spatial noise in gap junction coupling and pacemaker frequency. PMID:26869875

  10. Corepressive interaction and clustering of degrade-and-fire oscillators

    PubMed Central

    Fernandez, Bastien; Tsimring, Lev S.

    2016-01-01

    Strongly nonlinear degrade-and-fire (DF) oscillations may emerge in genetic circuits having a delayed negative feedback loop as their core element. Here we study the synchronization of DF oscillators coupled through a common repressor field. For weak coupling, initially distinct oscillators remain desynchronized. For stronger coupling, oscillators can be forced to wait in the repressed state until the global repressor field is sufficiently degraded, and then they fire simultaneously forming a synchronized cluster. Our analytical theory provides necessary and sufficient conditions for clustering and specifies the maximum number of clusters that can be formed in the asymptotic regime. We find that in the thermodynamic limit a phase transition occurs at a certain coupling strength from the weakly clustered regime with only microscopic clusters to a strongly clustered regime where at least one giant cluster has to be present. PMID:22181453

  11. Interaction of neutrons with layered magnetic media in oscillating magnetic field

    NASA Astrophysics Data System (ADS)

    Nikitenko, Yu. V.; Ignatovich, V. K.; Radu, F.

    2011-06-01

    New experimental possibilities of investigating layered magnetic structures in oscillating magnetic fields are discussed. Spin-flip and nonspin-flip neutron reflection and transmission probabilities show a frequency dependency near the magnetic neutron resonance condition. This allows to increase the precision of the static magnetic depth profile measurements of the magnetized matter. Moreover, this opens new possibilities of measuring the induction of the oscillating field inside the matter and determining the magnetic susceptibility of the oscillating magnetic field. Refraction of neutrons as they pass through a magnetic prism in the presence of an oscillating magnetic field is also investigated. A non-polarized neutron beam splits into eight spatially separated neutron beams, whose intensity and polarization depend on the strength and frequency of the oscillating field. Also, it is shown that the oscillating magnetic permeability of an angstrom-thick layer can be measured with a neutron wave resonator.

  12. Ultrafast Electronic Relaxation through a Conical Intersection: Nonadiabatic Dynamics Disentangled through an Oscillator Strength-Based Diabatization Framework

    DOE PAGES

    Medders, Gregory R.; Alguire, Ethan C.; Jain, Amber; ...

    2017-01-18

    Here, we employ surface hopping trajectories to model the short-time dynamics of gas-phase and partially solvated 4-(N,N-dimethylamino)benzonitrile (DMABN), a dual fluorescent molecule that is known to undergo a nonadiabatic transition through a conical intersection. To compare theory vs time-resolved fluorescence measurements, we calculate the mixed quantum–classical density matrix and the ensemble averaged transition dipole moment. We introduce a diabatization scheme based on the oscillator strength to convert the TDDFT adiabatic states into diabatic states of L a and L b character. Somewhat surprisingly, we find that the rate of relaxation reported by emission to the ground state is almost 50%more » slower than the adiabatic population relaxation. Although our calculated adiabatic rates are largely consistent with previous theoretical calculations and no obvious effects of decoherence are seen, the diabatization procedure introduced here enables an explicit picture of dynamics in the branching plane, raising tantalizing questions about geometric phase effects in systems with dozens of atoms.« less

  13. Indirect synchronization control in a starlike network of phase oscillators

    NASA Astrophysics Data System (ADS)

    Kuptsov, Pavel V.; Kuptsova, Anna V.

    2018-04-01

    A starlike network of non-identical phase oscillators is considered that contains the hub and tree rays each having a single node. In such network effect of indirect synchronization control is reported: changing the natural frequency and the coupling strength of one of the peripheral oscillators one can switch on an off the synchronization of the others. The controlling oscillator at that is not synchronized with them and has a frequency that is approximately four time higher then the frequency of the synchronization. The parameter planes showing a corresponding synchronization tongue are represented and time dependencies of phase differences are plotted for points within and outside of the tongue.

  14. A salt oscillator in the glacial Atlantic? 1. The concept

    NASA Astrophysics Data System (ADS)

    Broecker, Wallace S.; Bond, Gerard; Klas, Millie; Bonani, Georges; Wolfli, Willy

    1990-08-01

    As shown by the work of Dansgaard and his colleagues, climate oscillations of one or so millennia duration punctuate much of glacial section of the Greenland ice cores. These oscillations are characterized by 5°C air temperature changes, severalfold dust content changes and 50 ppm CO2 changes. Both the temperature and CO2 change are best explained by changes in the mode of operation of the ocean. In this paper we provide evidence which suggests that oscillations in surface water conditions of similar duration are present in the record from a deep sea core at 50°N. Based on this finding, we suggest that the Greenland climate changes are driven by oscillations in the salinity of the Atlantic Ocean which modulate the strength of the Atlantic's conveyor circulation.

  15. Superslow relaxation in identical phase oscillators with random and frustrated interactions

    NASA Astrophysics Data System (ADS)

    Daido, H.

    2018-04-01

    This paper is concerned with the relaxation dynamics of a large population of identical phase oscillators, each of which interacts with all the others through random couplings whose parameters obey the same Gaussian distribution with the average equal to zero and are mutually independent. The results obtained by numerical simulation suggest that for the infinite-size system, the absolute value of Kuramoto's order parameter exhibits superslow relaxation, i.e., 1/ln t as time t increases. Moreover, the statistics on both the transient time T for the system to reach a fixed point and the absolute value of Kuramoto's order parameter at t = T are also presented together with their distribution densities over many realizations of the coupling parameters.

  16. Gap junction plasticity as a mechanism to regulate network-wide oscillations

    PubMed Central

    Nicola, Wilten; Clopath, Claudia

    2018-01-01

    Cortical oscillations are thought to be involved in many cognitive functions and processes. Several mechanisms have been proposed to regulate oscillations. One prominent but understudied mechanism is gap junction coupling. Gap junctions are ubiquitous in cortex between GABAergic interneurons. Moreover, recent experiments indicate their strength can be modified in an activity-dependent manner, similar to chemical synapses. We hypothesized that activity-dependent gap junction plasticity acts as a mechanism to regulate oscillations in the cortex. We developed a computational model of gap junction plasticity in a recurrent cortical network based on recent experimental findings. We showed that gap junction plasticity can serve as a homeostatic mechanism for oscillations by maintaining a tight balance between two network states: asynchronous irregular activity and synchronized oscillations. This homeostatic mechanism allows for robust communication between neuronal assemblies through two different mechanisms: transient oscillations and frequency modulation. This implies a direct functional role for gap junction plasticity in information transmission in cortex. PMID:29529034

  17. Emergence of amplitude death scenario in a network of oscillators under repulsive delay interaction

    NASA Astrophysics Data System (ADS)

    Bera, Bidesh K.; Hens, Chittaranjan; Ghosh, Dibakar

    2016-07-01

    We report the existence of amplitude death in a network of identical oscillators under repulsive mean coupling. Amplitude death appears in a globally coupled network of identical oscillators with instantaneous repulsive mean coupling only when the number of oscillators is more than two. We further investigate that, amplitude death may emerge even in two coupled oscillators as well as network of oscillators if we introduce delay time in the repulsive mean coupling. We have analytically derived the region of amplitude death island and find out how strength of delay controls the death regime in two coupled or a large network of coupled oscillators. We have verified our results on network of delayed Mackey-Glass systems where parameters are set in hyperchaotic regime. We have also tested our coupling approach in two paradigmatic limit cycle oscillators: Stuart-Landau and Van der Pol oscillators.

  18. Periodic synchronization in a system of coupled phase oscillators with attractive and repulsive interactions

    NASA Astrophysics Data System (ADS)

    Yuan, Di; Tian, Jun-Long; Lin, Fang; Ma, Dong-Wei; Zhang, Jing; Cui, Hai-Tao; Xiao, Yi

    2018-06-01

    In this study we investigate the collective behavior of the generalized Kuramoto model with an external pinning force in which oscillators with positive and negative coupling strengths are conformists and contrarians, respectively. We focus on a situation in which the natural frequencies of the oscillators follow a uniform probability density. By numerically simulating the model, it is shown that the model supports multistable synchronized states such as a traveling wave state, π state and periodic synchronous state: an oscillating π state. The oscillating π state may be characterized by the phase distribution oscillating in a confined region and the phase difference between conformists and contrarians oscillating around π periodically. In addition, we present the parameter space of the oscillating π state and traveling wave state of the model.

  19. Electrical Oscillations in Two-Dimensional Microtubular Structures

    PubMed Central

    Cantero, María del Rocío; Perez, Paula L.; Smoler, Mariano; Villa Etchegoyen, Cecilia; Cantiello, Horacio F.

    2016-01-01

    Microtubules (MTs) are unique components of the cytoskeleton formed by hollow cylindrical structures of αβ tubulin dimeric units. The structural wall of the MT is interspersed by nanopores formed by the lateral arrangement of its subunits. MTs are also highly charged polar polyelectrolytes, capable of amplifying electrical signals. The actual nature of these electrodynamic capabilities remains largely unknown. Herein we applied the patch clamp technique to two-dimensional MT sheets, to characterize their electrical properties. Voltage-clamped MT sheets generated cation-selective oscillatory electrical currents whose magnitude depended on both the holding potential, and ionic strength and composition. The oscillations progressed through various modes including single and double periodic regimes and more complex behaviours, being prominent a fundamental frequency at 29 Hz. In physiological K+ (140 mM), oscillations represented in average a 640% change in conductance that was also affected by the prevalent anion. Current injection induced voltage oscillations, thus showing excitability akin with action potentials. The electrical oscillations were entirely blocked by taxol, with pseudo Michaelis-Menten kinetics and a KD of ~1.29 μM. The findings suggest a functional role of the nanopores in the MT wall on the genesis of electrical oscillations that offer new insights into the nonlinear behaviour of the cytoskeleton. PMID:27256791

  20. Properties of quasi-periodic oscillations in accreting magnetic white dwarfs

    NASA Technical Reports Server (NTRS)

    Wu, Kinwah; Chanmugam, G.; Shaviv, G.

    1992-01-01

    Previous studies of time-dependent accretion onto magnetic white dwarfs, in which the cooling was assumed to be due to bremsstrahlung emission, have shown that the accretion shock undergoes oscillations. However, when cyclotron cooling is also included, the oscillations are damped for sufficiently strong magnetic fields. Here we demonstrate that the oscillations can be sustained by accretion-fluctuation-induced excitations. The frequency of the QPOs are shown to increase quadratically with the magnetic field strength. We interpret the oscillations as a two-phase process in which bremsstrahlung cooling dominates in one half-cycle and cyclotron cooling in the other. Such a process may have very different consequences compared to a single-phase process where the functional form of the cooling is essentially the same throughout the cycle. If in the two-phase process damping occurs mainly in the cyclotron cooling half-cycle, there will be a universal effective damping factor which tends to suppress all oscillation modes indiscriminately. The oscillations of the accretion shock also could be a limit cycle process in which the system vacillates between two branches.

  1. The chimera state in colloidal phase oscillators with hydrodynamic interaction

    NASA Astrophysics Data System (ADS)

    Hamilton, Evelyn; Bruot, Nicolas; Cicuta, Pietro

    2017-12-01

    The chimera state is the incongruous situation where coherent and incoherent populations coexist in sets of identical oscillators. Using driven non-linear oscillators interacting purely through hydrodynamic forces at low Reynolds number, previously studied as a simple model of motile cilia supporting waves, we find concurrent incoherent and synchronised subsets in small arrays. The chimeras seen in simulation display a "breathing" aspect, reminiscent of uniformly interacting phase oscillators. In contrast to other systems where chimera has been observed, this system has a well-defined interaction metric, and we know that the emergent dynamics inherit the symmetry of the underlying Oseen tensor eigenmodes. The chimera state can thus be connected to a superposition of eigenstates, whilst considering the mean interaction strength within and across subsystems allows us to make a connection to more generic (and abstract) chimeras in populations of Kuramoto phase oscillators. From this work, we expect the chimera state to emerge in experimental observations of oscillators coupled through hydrodynamic forces.

  2. Coupling strength assumption in statistical energy analysis

    PubMed Central

    Lafont, T.; Totaro, N.

    2017-01-01

    This paper is a discussion of the hypothesis of weak coupling in statistical energy analysis (SEA). The examples of coupled oscillators and statistical ensembles of coupled plates excited by broadband random forces are discussed. In each case, a reference calculation is compared with the SEA calculation. First, it is shown that the main SEA relation, the coupling power proportionality, is always valid for two oscillators irrespective of the coupling strength. But the case of three subsystems, consisting of oscillators or ensembles of plates, indicates that the coupling power proportionality fails when the coupling is strong. Strong coupling leads to non-zero indirect coupling loss factors and, sometimes, even to a reversal of the energy flow direction from low to high vibrational temperature. PMID:28484335

  3. Enhanced entrainability of genetic oscillators by period mismatch

    PubMed Central

    Hasegawa, Yoshihiko; Arita, Masanori

    2013-01-01

    Biological oscillators coordinate individual cellular components so that they function coherently and collectively. They are typically composed of multiple feedback loops, and period mismatch is unavoidable in biological implementations. We investigated the advantageous effect of this period mismatch in terms of a synchronization response to external stimuli. Specifically, we considered two fundamental models of genetic circuits: smooth and relaxation oscillators. Using phase reduction and Floquet multipliers, we numerically analysed their entrainability under different coupling strengths and period ratios. We found that a period mismatch induces better entrainment in both types of oscillator; the enhancement occurs in the vicinity of the bifurcation on their limit cycles. In the smooth oscillator, the optimal period ratio for the enhancement coincides with the experimentally observed ratio, which suggests biological exploitation of the period mismatch. Although the origin of multiple feedback loops is often explained as a passive mechanism to ensure robustness against perturbation, we study the active benefits of the period mismatch, which include increasing the efficiency of the genetic oscillators. Our findings show a qualitatively different perspective for both the inherent advantages of multiple loops and their essentiality. PMID:23389900

  4. Experience of the fibrotest for measuring cotton fiber length and strength properties

    USDA-ARS?s Scientific Manuscript database

    The Fibrotest is a device developed by Textechno for measuring cotton fiber length and strength properties. The Fibrotest provides abundant information, including more than 20 length and strength parameters in absolute and relative modes, and displays fibrogram, load-elongation curve, and fiber bea...

  5. Coupled Oscillator Model of the Business Cycle withFluctuating Goods Markets

    NASA Astrophysics Data System (ADS)

    Ikeda, Y.; Aoyama, H.; Fujiwara, Y.; Iyetomi, H.; Ogimoto, K.; Souma, W.; Yoshikawa, H.

    The sectoral synchronization observed for the Japanese business cycle in the Indices of Industrial Production data is an example of synchronization. The stability of this synchronization under a shock, e.g., fluctuation of supply or demand, is a matter of interest in physics and economics. We consider an economic system made up of industry sectors and goods markets in order to analyze the sectoral synchronization observed for the Japanese business cycle. A coupled oscillator model that exhibits synchronization is developed based on the Kuramoto model with inertia by adding goods markets, and analytic solutions of the stationary state and the coupling strength are obtained. We simulate the effects on synchronization of a sectoral shock for systems with different price elasticities and the coupling strengths. Synchronization is reproduced as an equilibrium solution in a nearest neighbor graph. Analysis of the order parameters shows that the synchronization is stable for a finite elasticity, whereas the synchronization is broken and the oscillators behave like a giant oscillator with a certain frequency additional to the common frequency for zero elasticity.

  6. Dysrhythmias of the respiratory oscillator

    NASA Astrophysics Data System (ADS)

    Paydarfar, David; Buerkel, Daniel M.

    1995-03-01

    Breathing is regulated by a central neural oscillator that produces rhythmic output to the respiratory muscles. Pathological disturbances in rhythm (dysrhythmias) are observed in the breathing pattern of children and adults with neurological and cardiopulmonary diseases. The mechanisms responsible for genesis of respiratory dysrhythmias are poorly understood. The present studies take a novel approach to this problem. The basic postulate is that the rhythm of the respiratory oscillator can be altered by a variety of stimuli. When the oscillator recovers its rhythm after such perturbations, its phase may be reset relative to the original rhythm. The amount of phase resetting is dependent upon stimulus parameters and the level of respiratory drive. The long-range hypothesis is that respiratory dysrhythmias can be induced by stimuli that impinge upon or arise within the respiratory oscillator with certain combinations of strength and timing relative to the respiratory cycle. Animal studies were performed in anesthetized or decerebrate preparations. Neural respiratory rhythmicity is represented by phrenic nerve activity, allowing use of open-loop experimental conditions which avoid negative chemical feedback associated with changes in ventilation. In animal experiments, respiratory dysrhythmias can be induced by stimuli having specific combinations of strength and timing. Newborn animals readily exhibit spontaneous dysrhythmias which become more prominent at lower respiratory drives. In human subjects, swallowing was studied as a physiological perturbation of respiratory rhythm, causing a pattern of phase resetting that is characterized topologically as type 0. Computational studies of the Bonhoeffer-van der Pol (BvP) equations, whose qualitative behavior is representative of many excitable systems, supports a unified interpretation of these experimental findings. Rhythmicity is observed when the BvP model exhibits recurrent periods of excitation alternating with

  7. Direct measurement of the absolute absorption spectrum of individual semiconducting single-wall carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Blancon, Jean-Christophe; Paillet, Matthieu; Tran, Huy Nam; Than, Xuan Tinh; Guebrou, Samuel Aberra; Ayari, Anthony; Miguel, Alfonso San; Phan, Ngoc-Minh; Zahab, Ahmed-Azmi; Sauvajol, Jean-Louis; Fatti, Natalia Del; Vallée, Fabrice

    2013-09-01

    The optical properties of single-wall carbon nanotubes are very promising for developing novel opto-electronic components and sensors with applications in many fields. Despite numerous studies performed using photoluminescence or Raman and Rayleigh scattering, knowledge of their optical response is still partial. Here we determine using spatial modulation spectroscopy, over a broad optical spectral range, the spectrum and amplitude of the absorption cross-section of individual semiconducting single-wall carbon nanotubes. These quantitative measurements permit determination of the oscillator strength of the different excitonic resonances and their dependencies on the excitonic transition and type of semiconducting nanotube. A non-resonant background is also identified and its cross-section comparable to the ideal graphene optical absorbance. Furthermore, investigation of the same single-wall nanotube either free standing or lying on a substrate shows large broadening of the excitonic resonances with increase of oscillator strength, as well as stark weakening of polarization-dependent antenna effects, due to nanotube-substrate interaction.

  8. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  9. Free Oscillations of the Facula Node at the Stage of Slow Dissipation

    NASA Astrophysics Data System (ADS)

    Solov'ev, A. A.; Kirichek, E. A.; Efremov, V. I.

    2017-12-01

    A solar faculae having an appearance of quite long-lived magnetic nodes can perform (as well as sunspots, chromospheric filaments, coronal loops) free oscillations, i.e., they can oscillate about the stable equilibrium position as a single whole, changing quasi-periodically magnetic field averaged over the section with periods from 1 to 4 hours. Kolotkov et al. (2017) described the case in which the average magnetic field strength of the facula node considerably decreased during observations of SDO magnetograms (13 hours), and, at the same time, its oscillations acquired a specific character: the fundamental mode of free oscillations of the facula considerably increased in amplitude (by approximately two times), while the period of oscillations increased by three times. At the end of the process, the system dissipated. In this work, we present the exact solution of the equation of small-amplitude oscillations of the system with a time-variable rigidity, describing the oscillation behavior at which the elasticity of the system decreases with time, while the period and amplitude of oscillations grow.

  10. Synchronization and desynchronization in a network of locally coupled Wilson-Cowan oscillators.

    PubMed

    Campbell, S; Wang, D

    1996-01-01

    A network of Wilson-Cowan (WC) oscillators is constructed, and its emergent properties of synchronization and desynchronization are investigated by both computer simulation and formal analysis. The network is a 2D matrix, where each oscillator is coupled only to its neighbors. We show analytically that a chain of locally coupled oscillators (the piecewise linear approximation to the WC oscillator) synchronizes, and we present a technique to rapidly entrain finite numbers of oscillators. The coupling strengths change on a fast time scale based on a Hebbian rule. A global separator is introduced which receives input from and sends feedback to each oscillator in the matrix. The global separator is used to desynchronize different oscillator groups. Unlike many other models, the properties of this network emerge from local connections that preserve spatial relationships among components and are critical for encoding Gestalt principles of feature grouping. The ability to synchronize and desynchronize oscillator groups within this network offers a promising approach for pattern segmentation and figure/ground segregation based on oscillatory correlation.

  11. Stellar Laboratories: 3. New Ba 5, Ba 6, and Ba 7 Oscillator Strengths and the Barium Abundance in the Hot White Dwarfs G191-B2B and RE 0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, Jeffrey Walter

    2014-01-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims. Reliable Ba 5-7 oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods. We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results. For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g=7.5. The Ba abundance is 3.5 +/- 0.5 × 10(exp-4) (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 +/- 0.5 × 10(exp-6) (about 265 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely.

  12. Gamma oscillations in a nonlinear regime: a minimal model approach using heterogeneous integrate-and-fire networks.

    PubMed

    Bathellier, Brice; Carleton, Alan; Gerstner, Wulfram

    2008-12-01

    Fast oscillations and in particular gamma-band oscillation (20-80 Hz) are commonly observed during brain function and are at the center of several neural processing theories. In many cases, mathematical analysis of fast oscillations in neural networks has been focused on the transition between irregular and oscillatory firing viewed as an instability of the asynchronous activity. But in fact, brain slice experiments as well as detailed simulations of biological neural networks have produced a large corpus of results concerning the properties of fully developed oscillations that are far from this transition point. We propose here a mathematical approach to deal with nonlinear oscillations in a network of heterogeneous or noisy integrate-and-fire neurons connected by strong inhibition. This approach involves limited mathematical complexity and gives a good sense of the oscillation mechanism, making it an interesting tool to understand fast rhythmic activity in simulated or biological neural networks. A surprising result of our approach is that under some conditions, a change of the strength of inhibition only weakly influences the period of the oscillation. This is in contrast to standard theoretical and experimental models of interneuron network gamma oscillations (ING), where frequency tightly depends on inhibition strength, but it is similar to observations made in some in vitro preparations in the hippocampus and the olfactory bulb and in some detailed network models. This result is explained by the phenomenon of suppression that is known to occur in strongly coupled oscillating inhibitory networks but had not yet been related to the behavior of oscillation frequency.

  13. Mapping absolute tissue endogenous fluorophore concentrations with chemometric wide-field fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Zhang; Reilley, Michael; Li, Run; Xu, Min

    2017-06-01

    We report chemometric wide-field fluorescence microscopy for imaging the spatial distribution and concentration of endogenous fluorophores in thin tissue sections. Nonnegative factorization aided by spatial diversity is used to learn both the spectral signature and the spatial distribution of endogenous fluorophores from microscopic fluorescence color images obtained under broadband excitation and detection. The absolute concentration map of individual fluorophores is derived by comparing the fluorescence from "pure" fluorophores under the identical imaging condition following the identification of the fluorescence species by its spectral signature. This method is then demonstrated by characterizing the concentration map of endogenous fluorophores (including tryptophan, elastin, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide) for lung tissue specimens. The absolute concentrations of these fluorophores are all found to decrease significantly from normal, perilesional, to cancerous (squamous cell carcinoma) tissue. Discriminating tissue types using the absolute fluorophore concentration is found to be significantly more accurate than that achievable with the relative fluorescence strength. Quantification of fluorophores in terms of the absolute concentration map is also advantageous in eliminating the uncertainties due to system responses or measurement details, yielding more biologically relevant data, and simplifying the assessment of competing imaging approaches.

  14. Synchronization of electrically coupled micromechanical oscillators with a frequency ratio of 3:1

    NASA Astrophysics Data System (ADS)

    Pu, Dong; Wei, Xueyong; Xu, Liu; Jiang, Zhuangde; Huan, Ronghua

    2018-01-01

    In this Letter, synchronization of micromechanical oscillators with a frequency ratio of 3:1 is reported. Two electrically coupled piezoresistive micromechanical oscillators are built for the study, and their oscillation frequencies are tuned via the Joule heating effect to find out the synchronization region. Experimental results show that the larger coupling strength or bias driving voltage is applied and a wider synchronization region is obtained. Interestingly, however, the oscillator's frequency tunability is dramatically reduced from -809.1 Hz/V to -23.1 Hz/V when synchronization is reached. A nearly 10-fold improvement of frequency stability at 1 s is observed from one of the synchronized oscillators, showing a comparable performance of the other. The stable high order synchronization of micromechanical oscillators is helpful to design high performance resonant sensors with a better frequency resolution and a larger scale factor.

  15. Disruptions of El Niño–Southern Oscillation teleconnections by the Madden–Julian Oscillation

    USGS Publications Warehouse

    Hoell, Andrew; Barlow, Mathew; Wheeler, Mathew; Funk, Christopher C.

    2014-01-01

    The El Niño–Southern Oscillation (ENSO) is the leading mode of interannual variability, with global impacts on weather and climate that have seasonal predictability. Research on the link between interannual ENSO variability and the leading mode of intraseasonal variability, the Madden–Julian oscillation (MJO), has focused mainly on the role of MJO initiating or terminating ENSO. We use observational analysis and modeling to show that the MJO has an important simultaneous link to ENSO: strong MJO activity significantly weakens the atmospheric branch of ENSO. For weak MJO conditions relative to strong MJO conditions, the average magnitude of ENSO-associated tropical precipitation anomalies increases by 63%, and the strength of hemispheric teleconnections increases by 58%. Since the MJO has predictability beyond three weeks, the relationships shown here suggest that there may be subseasonal predictability of the ENSO teleconnections to continental circulation and precipitation.

  16. Relationships Between Concentric and Eccentric Strength and Countermovement Jump Performance in Resistance Trained Men.

    PubMed

    Bridgeman, Lee A; McGuigan, Michael R; Gill, Nicholas D; Dulson, Deborah K

    2018-01-01

    Bridgeman, LA, McGuigan, MR, Gill, ND, and Dulson, DK. Relationships between concentric and eccentric strength and countermovement jump performance in resistance trained men. J Strength Cond Res 32(1): 255-260, 2018-The purpose of this study was to investigate the relationships between concentric and eccentric peak force (PF) and countermovement jump (CMJ) performance in resistance trained men. Subjects were 12 men (mean ± SD; age: 25.4 ± 3.5 years; height: 177.2 ± 4.5 cm; mass: 84.0 ± 10.1 kg). The men were tested for concentric and eccentric PF using the Exerbotics squat device. Subjects then completed 3 CMJs to allow for the calculation of peak power (PP), peak ground reaction force, and jump height (JH). Correlations between the variables of interest were calculated using Pearson product-moment correlation coefficients. A large relationship was found between absolute concentric PF and absolute CMJ PP (r = 0.66, p ≤ 0.05). Absolute eccentric PF had a very large relationship with absolute CMJ PP and CMJ JH (r = 0.74, p < 0.01 and r = 0.74, p < 0.001, respectively). In addition, absolute eccentric PF was found to have a moderate relationship with relative CMJ PP (r = 0.58, p ≤ 0.05). Relative eccentric PF was had a very large relationship with relative CMJ PP and CMJ JH (r = 0.73, p < 0.001 and r = 0.79, p < 0.001, respectively). Based on these findings, strength and conditioning coaches and athletes who wish to enhance CMJ performance may wish to include exercises, which enhance lower-body eccentric strength within their training.

  17. Excitation energies, oscillator strengths and lifetimes in Mg-like vanadium

    NASA Astrophysics Data System (ADS)

    Gupta, G. P.; Msezane, A. Z.

    2013-08-01

    Excitation energies from the ground state for 86 fine-structure levels as well as oscillator strengths and radiative decay rates for all fine-structure transitions among the levels of the terms (1s22s22p6)3s2(1S), 3s3p(1,3Po), 3s3d(1,3D), 3s4s(1,3S), 3s4p(1,3Po), 3s4d(1,3D), 3s4f(1,3Fo), 3p2(1S, 3P, 1D), 3p3d(1,3Po, 1,3Do, 1,3Fo), 3p4s(1,3Po), 3p4p(1,3S, 1,3P, 1,3D), 3p4d(1,3Po, 1,3Do, 1,3Fo), 3p4f(1,3D, 1,3F, 1,3G) and 3d2(1S, 3P, 1D,3F,1G) of V XII are calculated using extensive configuration-interaction wave functions obtained with the configuration-interaction version 3 computer code of Hibbert. The important relativistic effects in intermediate coupling are included through the Breit-Pauli approximation. In order to keep our calculated energy splittings as close as possible to the corresponding experimental values, we have made small adjustments to the diagonal elements of the Hamiltonian matrices. The mixing among several fine-structure levels is found to be very strong. Our fine-tuned excitation energies, including their ordering, are in excellent agreement (better than 0.25%) with the available experimental results. From our calculated radiative decay rates, we have also calculated the radiative lifetimes of fine-structure levels. Generally, our calculated data for the excitation energies and radiative decay rates are found to agree reasonably well with other available calculations. However, significant differences between our calculated lifetimes and those from the calculation of Froese Fischer et al (2006 At. Data Nucl. Data Tables 92 607) for a few fine-structure levels, mainly those belonging to the 3p4d configuration, are noted and discussed. Also, our calculated lifetime for the longer-lived level 3s3p(3P1) is found to be in excellent agreement with the corresponding value of Curtis (1991 Phys. Scr. 43 137). ) for all 1108 transitions in V XII are available with the first author ().

  18. Stellar laboratories . IX. New Se v, Sr iv-vii, Te vi, and I vi oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Quinet, P.; Knörzer, M.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

    2017-10-01

    Context. To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is crucial for the calculation of such model atmospheres. Aims: We aim to calculate new Sr iv-vii oscillator strengths to identify for the first time Sr spectral lines in hot white dwarf (WD) stars and to determine the photospheric Sr abundances. To measure the abundances of Se, Te, and I in hot WDs, we aim to compute new Se v, Te vi, and I vi oscillator strengths. Methods: To consider radiative and collisional bound-bound transitions of Se v, Sr iv - vii, Te vi, and I vi in our NLTE atmosphere models, we calculated oscillator strengths for these ions. Results: We newly identified four Se v, 23 Sr v, 1 Te vi, and three I vi lines in the ultraviolet (UV) spectrum of RE 0503-289. We measured a photospheric Sr abundance of 6.5+ 3.8-2.4× 10-4 (mass fraction, 9500-23 800 times solar). We determined the abundances of Se (1.6+ 0.9-0.6× 10-3, 8000-20 000), Te (2.5+ 1.5-0.9× 10-4, 11 000-28 000), and I (1.4+ 0.8-0.5× 10-5, 2700-6700). No Se, Sr, Te, and I line was found in the UV spectra of G191-B2B and we could determine only upper abundance limits of approximately 100 times solar. Conclusions: All identified Se v, Sr v, Te vi, and I vi lines in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Full Tables A.15 to A.21 are only available via the German Astrophysical Virtual Observatory (GAVO) service TOSS (http://dc.g-vo.org/TOSS).

  19. Analysis of a 12-Hour Artifact in LF Oscillations of the Magnetic Field of Sunspots According to SDO/HMI Data

    NASA Astrophysics Data System (ADS)

    Efremov, V. I.; Parfinenko, L. D.; Solov'ev, A. A.

    2017-12-01

    The properties of the 12-h artifact in the data of the SDO/HMI instrument (Helioseismic and Magnetic Imager) caused by the nonzero radial velocity of the station relative to the Sun are investigated. The study has been carried out with respect to long-period oscillations of the magnetic field of sunspots for different station positions in the Earth's orbit by the alternative spectral method of singular decomposition of the signal CaterPillarSSA. Features of artifact filtering, both in special positions of the station (at the points of aphelion and perihelion) and at arbitrarily selected orbital points, are considered. It is shown that the 12-h artifact mode can be completely filtered from the time series of the observed variable, not only at these two orbital points (because of the symmetry of the station's radial velocity with respect to the zero mean here) but also at any others. It is shown that only a 12-h mode is physically justified, while the 24-h harmonic appears only as an artifact in the Fourier decomposition of the amplitude-modulated signal. It is emphasized that the values of the magnetic field measured with SDO/HMI are sensitive only to the station's radial velocity absolute values with respect to the Sun and do not depend on its direction. It has been noted that the periods of sunspot oscillation as a whole obtained from SDO/HMI data after orbital artifact filtration fit well into the dependence diagram of the period of sunspot oscillations on the value of its magnetic field strength constructed earlier by SOHO/MDIdata.

  20. MHD oscillations observed in the solar photosphere with the Michelson Doppler Imager

    NASA Astrophysics Data System (ADS)

    Norton, A.; Ulrich, R. K.; Bogart, R. S.; Bush, R. I.; Hoeksema, J. T.

    Magnetohydrodynamic oscillations are observed in the solar photosphere with the Michelson Doppler Imager (MDI). Images of solar surface velocity and magnetic field strength with 4'' spatial resolution and a 60 second temporal resolution are analyzed. A two dimensional gaussian aperture with a FWHM of 10'' is applied to the data in regions of sunspot, plage and quiet sun and the resulting averaged signal is returned each minute. Significant power is observed in the magnetic field oscillations with periods of five minutes. The effect of misregistration between MDI's left circularly polarized (LCP) and right circularly polarized (RCP) images has been investigated and is found not to be the cause of the observed magnetic oscillations. It is assumed that the large amplitude acoustic waves with 5 minute periods are the driving mechanism behind the magnetic oscillations. The nature of the magnetohydrodynamic oscillations are characterized by their phase relations with simultaneously observed solar surface velocity oscillations.

  1. Lifetime measurements using two-step laser excitation for high-lying even-parity levels and improved theoretical oscillator strengths in Y II

    NASA Astrophysics Data System (ADS)

    Palmeri, P.; Quinet, P.; Lundberg, H.; Engström, L.; Nilsson, H.; Hartman, H.

    2017-10-01

    We report new time-resolved laser-induced fluorescence lifetime measurements for 22 highly excited even-parity levels in singly ionized yttrium (Y II). To populate these levels belonging to the configurations 4d6s, 5s6s 4d5d, 5p2, 4d7s and 4d6d, a two-step laser excitation technique was used. Our previous pseudo-relativistic Hartree-Fock model (Biémont et al. 2011) was improved by extending the configuration interaction up to n = 10 to reproduce the new experimental lifetimes. A set of semi-empirical oscillator strengths extended to transitions falling in the spectral range λλ194-3995 nm, depopulating these 22 even-parity levels in Y II, is presented and compared to the values found in the Kurucz's data base (Kurucz 2011).

  2. Electron impact collision strengths in Ne VII

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

    Di, L.; Shi, J.R.; Zhao, G., E-mail: gzhao@bao.ac.cn

    2012-07-15

    The lines of Ne VII have been observed in many astronomical objects, and some transitions from high energy levels were observed both in Seyfert galaxies and stellar coronae. Thus, the atomic data for these transitions are important for modeling. Using the code FAC we calculated the collision strengths based on the distorted-wave method with large configuration interactions included. The Maxwellian averaged effective collision strengths covering the typical temperature range of astronomical and laboratory hot plasmas are presented. We extend the calculation of the energy levels to n=4 and 5. The energy levels, wavelengths, spontaneous transition rates, weighted oscillator strengths, andmore » effective collision strengths were reported. Compared with the results from experiment or previous theoretical calculations a general agreement is found. It is found that the resonance effects are important in calculating the effective collision strengths.« less

  3. The Effect of Inhibitory Neuron on the Evolution Model of Higher-Order Coupling Neural Oscillator Population

    PubMed Central

    Qi, Yi; Wang, Rubin; Jiao, Xianfa; Du, Ying

    2014-01-01

    We proposed a higher-order coupling neural network model including the inhibitory neurons and examined the dynamical evolution of average number density and phase-neural coding under the spontaneous activity and external stimulating condition. The results indicated that increase of inhibitory coupling strength will cause decrease of average number density, whereas increase of excitatory coupling strength will cause increase of stable amplitude of average number density. Whether the neural oscillator population is able to enter the new synchronous oscillation or not is determined by excitatory and inhibitory coupling strength. In the presence of external stimulation, the evolution of the average number density is dependent upon the external stimulation and the coupling term in which the dominator will determine the final evolution. PMID:24516505

  4. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  5. Aligning Plasma-Arc Welding Oscillations

    NASA Technical Reports Server (NTRS)

    Norris, Jeff; Fairley, Mike

    1989-01-01

    Tool aids in alignment of oscillator probe on variable-polarity plasma-arc welding torch. Probe magnetically pulls arc from side to side as it moves along joint. Tensile strength of joint depends on alignment of weld bead and on alignment of probe. Operator installs new tool on front of torch body, levels it with built-in bubble glass, inserts probe in slot on tool, and locks probe in place. Procedure faster and easier and resulting alignment more accurate and repeatable.

  6. Stellar laboratories. VII. New Kr iv - vii oscillator strengths and an improved spectral analysis of the hot, hydrogen-deficient DO-type white dwarf RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Quinet, P.; Hoyer, D.; Werner, K.; Richter, P.; Kruk, J. W.; Demleitner, M.

    2016-05-01

    Context. For the spectral analysis of high-resolution and high signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: New Kr iv-vii oscillator strengths for a large number of lines enable us to construct more detailed model atoms for our NLTE model-atmosphere calculations. This enables us to search for additional Kr lines in observed spectra and to improve Kr abundance determinations. Methods: We calculated Kr iv-vii oscillator strengths to consider radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Kr lines that are exhibited in high-resolution and high S/N ultraviolet (UV) observations of the hot white dwarf RE 0503-289. Results: We reanalyzed the effective temperature and surface gravity and determined Teff = 70000 ± 2000 K and log (g/ cm s-2) = 7.5 ± 0.1. We newly identified ten Kr v lines and one Kr vi line in the spectrum of RE 0503-289. We measured a Kr abundance of -3.3 ± 0.3 (logarithmic mass fraction). We discovered that the interstellar absorption toward RE 0503-289 has a multi-velocity structure within a radial-velocity interval of -40 km s-1oscillator strengths. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26666. Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. Based on

  7. Quantum oscillations in insulators with neutral Fermi surfaces

    NASA Astrophysics Data System (ADS)

    Sodemann, Inti; Chowdhury, Debanjan; Senthil, T.

    2018-02-01

    We develop a theory of quantum oscillations in insulators with an emergent Fermi sea of neutral fermions minimally coupled to an emergent U(1 ) gauge field. As pointed out by Motrunich [Phys. Rev. B 73, 155115 (2006), 10.1103/PhysRevB.73.155115], in the presence of a physical magnetic field the emergent magnetic field develops a nonzero value leading to Landau quantization for the neutral fermions. We focus on the magnetic field and temperature dependence of the analog of the de Haas-van Alphen effect in two and three dimensions. At temperatures above the effective cyclotron energy, the magnetization oscillations behave similarly to those of an ordinary metal, albeit in a field of a strength that differs from the physical magnetic field. At low temperatures, the oscillations evolve into a series of phase transitions. We provide analytical expressions for the amplitude and period of the oscillations in both of these regimes and simple extrapolations that capture well their crossover. We also describe oscillations in the electrical resistivity of these systems that are expected to be superimposed with the activated temperature behavior characteristic of their insulating nature and discuss suitable experimental conditions for the observation of these effects in mixed-valence insulators and triangular lattice organic materials.

  8. Phase diagram for the Winfree model of coupled nonlinear oscillators.

    PubMed

    Ariaratnam, J T; Strogatz, S H

    2001-05-07

    In 1967 Winfree proposed a mean-field model for the spontaneous synchronization of chorusing crickets, flashing fireflies, circadian pacemaker cells, or other large populations of biological oscillators. Here we give the first bifurcation analysis of the model, for a tractable special case. The system displays rich collective dynamics as a function of the coupling strength and the spread of natural frequencies. Besides incoherence, frequency locking, and oscillator death, there exist hybrid solutions that combine two or more of these states. We present the phase diagram and derive several of the stability boundaries analytically.

  9. Phase Diagram for the Winfree Model of Coupled Nonlinear Oscillators

    NASA Astrophysics Data System (ADS)

    Ariaratnam, Joel T.; Strogatz, Steven H.

    2001-05-01

    In 1967 Winfree proposed a mean-field model for the spontaneous synchronization of chorusing crickets, flashing fireflies, circadian pacemaker cells, or other large populations of biological oscillators. Here we give the first bifurcation analysis of the model, for a tractable special case. The system displays rich collective dynamics as a function of the coupling strength and the spread of natural frequencies. Besides incoherence, frequency locking, and oscillator death, there exist hybrid solutions that combine two or more of these states. We present the phase diagram and derive several of the stability boundaries analytically.

  10. Strategy for the absolute neutron emission measurement on ITER.

    PubMed

    Sasao, M; Bertalot, L; Ishikawa, M; Popovichev, S

    2010-10-01

    Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10) n/s (neutron/second) for DT and 10(8) n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.

  11. Immunological parameters in elderly women: correlations with aerobic power, muscle strength and mood state.

    PubMed

    Raso, Vagner; Natale, Valéria Maria; Duarte, Alberto José da Silva; Greve, Júlia Maria D'Andrea; Shephard, Roy J

    2012-05-01

    Our objective was to relate immunological data for healthy but sedentary elderly women to aerobic power, strength, and mood state. We measured peak aerobic power and one-repetition maximum strength along with mood (depression and fatigue), quality of life and carbohydrate intake on 42 women aged 60-77 years. Standard immunological techniques determined natural killer cell count and cytotoxic activity (NKCA), proliferative responses to phytohemaglutinin and OKT(3), various lymphocyte subpopulations (CD3(+), CD3(-)CD19(+), CD56(+), CD4(+), CD8(+), CD56(dim) and CD56(bright)), and markers of activation, maturation, down-regulation and susceptibility to apoptosis (CD25(+), CD28(+), CD45RA(+), CD45RO(+), CD69(+), CD95(+), HLA-DR(+)). Correlations of immune parameters with aerobic power and strength were very similar for absolute and relative immunological data. In the group as a whole, the only correlation with aerobic power was -0.35 (relative CD4(+)CD69(+) count), but in subjects with values <22.6 mL kg(-1)min(-1) correlations ranged from -0.57 (relative CD4(+)CD45RO(+)) to 0.92 (absolute CD56(dim)HLA-DR(+)). In terms of muscle strength, univariate correlation coefficients ranged from -0.34 (relative and absolute CD3(+)CD4(+)CD8(+)) to +0.48 (absolute CD3(+)HLA-DR(+)) and +0.50 (absolute CD8(+)CD45RA(+)CD45RO(+)). Neither NKCA nor lymphocyte proliferation were correlated with aerobic power or muscle strength. Although mood state and quality of life can sometimes be influenced by an individual's fitness level, our multivariate analyses suggested that depression, fatigue and quality of life were more important determinants of immune profile than our fitness measures. Psychological changes associated with aging may have a substantial adverse effect upon the immune system, and immunological function may be enhanced more by addressing these issues than by focusing upon aerobic or resistance training. Copyright © 2012 Elsevier Inc. All rights reserved.

  12. Absolutely relative or relatively absolute: violations of value invariance in human decision making.

    PubMed

    Teodorescu, Andrei R; Moran, Rani; Usher, Marius

    2016-02-01

    Making decisions based on relative rather than absolute information processing is tied to choice optimality via the accumulation of evidence differences and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to absolute intensities that maintain differences and ratios, respectively. While information about the absolute values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision. To test the sensitivity of human decision making to absolute values, we manipulated the intensities of brightness stimuli pairs while preserving either their differences or their ratios. Although asked to choose the brighter alternative relative to the other, participants responded faster to higher absolute values. Thus, our results provide empirical evidence for human sensitivity to task irrelevant absolute values indicating a hard-wired mechanism that precedes executive control. Computational investigations of several modelling architectures reveal two alternative accounts for this phenomenon, which combine absolute and relative processing. One account involves accumulation of differences with activation dependent processing noise and the other emerges from accumulation of absolute values subject to the temporal dynamics of lateral inhibition. The potential adaptive role of such choice mechanisms is discussed.

  13. Stellar Laboratories II. New Zn Iv and Zn v Oscillator Strengths and Their Validation in the Hot White Dwarfs G191-B2B and RE0503-289

    NASA Technical Reports Server (NTRS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-01-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (SN) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191B2B,21 Zn iv lines were newly identified. Because of the lack of Zn iv data, transition probabilities of the isoelectronic Ge vi were adapted for a first, coarse determination of the photospheric Zn abundance.Aims. Reliable Zn iv and Zn v oscillator strengths are used to improve the Zn abundance determination and to identify more Zn lines in the spectra of G191B2B and the DO-type white dwarf RE 0503289. Methods. We performed new calculations of Zn iv and Zn v oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn iv v spectrum exhibited in high-resolution and high-SN UV observations of G191B2B and RE 0503289. Results. In the UV spectrum of G191B2B, we identify 31 Zn iv and 16 Zn v lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn 5.52 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn iv Zn v ionization equilibrium, which is a very sensitive Teff indicator, is well reproduced with the previously determined Teff 60 000 2000 K and log g 7.60 0.05. In the spectrum of RE 0503289, we identified 128 Zn v lines for the first time and determined log Zn 3.57 0.2 (155 times solar). Conclusions. Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn iv and Zn v line profiles in two white dwarf (G191B2B and RE 0503289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to determine the

  14. Time-shifted synchronization of chaotic oscillator chains without explicit coupling delays.

    PubMed

    Blakely, Jonathan N; Stahl, Mark T; Corron, Ned J

    2009-12-01

    We examine chains of unidirectionally coupled oscillators in which time-shifted synchronization occurs without explicit delays in the coupling. In numerical simulations and in an experimental system of electronic oscillators, we examine the time shift and the degree of distortion (primarily in the form of attenuation) of the waveforms of the oscillators located far from the drive oscillator. Surprisingly, under weak coupling we observe minimal attenuation in spite of a significant total time shift. In contrast, at higher coupling strengths the observed attenuation increases dramatically and approaches the value predicted by an analytically derived estimate. In this regime, we verify directly that generalized synchronization is maintained over the entire chain length despite severe attenuation. These results suggest that weak coupling generally may produce higher quality synchronization in systems for which truly identical synchronization is not possible.

  15. Disorder effect on the Friedel oscillations in a one-dimensional Mott insulator

    NASA Astrophysics Data System (ADS)

    Weiss, Y.; Goldstein, M.; Berkovits, R.

    2007-07-01

    The Friedel oscillations resulting from coupling a quantum dot to one edge of a disordered one-dimensional wire in the Mott insulator regime are calculated numerically using the density matrix renormalization group method. By investigating the influence of a constant weak disorder on the Friedel oscillations decay we find that the effect of disorder is reduced by increasing the interaction strength. This behavior is opposite to the recently reported influence of disorder in the Anderson insulator regime.

  16. Robustness of synthetic oscillators in growing and dividing cells

    NASA Astrophysics Data System (ADS)

    Paijmans, Joris; Lubensky, David K.; Rein ten Wolde, Pieter

    2017-05-01

    Synthetic biology sets out to implement new functions in cells, and to develop a deeper understanding of biological design principles. Elowitz and Leibler [Nature (London) 403, 335 (2000), 10.1038/35002125] showed that by rational design of the reaction network, and using existing biological components, they could create a network that exhibits periodic gene expression, dubbed the repressilator. More recently, Stricker et al. [Nature (London) 456, 516 (2008), 10.1038/nature07389] presented another synthetic oscillator, called the dual-feedback oscillator, which is more stable. Detailed studies have been carried out to determine how the stability of these oscillators is affected by the intrinsic noise of the interactions between the components and the stochastic expression of their genes. However, as all biological oscillators reside in growing and dividing cells, an important question is how these oscillators are perturbed by the cell cycle. In previous work we showed that the periodic doubling of the gene copy numbers due to DNA replication can couple not only natural, circadian oscillators to the cell cycle [Paijmans et al., Proc. Natl. Acad. Sci. (USA) 113, 4063 (2016), 10.1073/pnas.1507291113], but also these synthetic oscillators. Here we expand this study. We find that the strength of the locking between oscillators depends not only on the positions of the genes on the chromosome, but also on the noise in the timing of gene replication: noise tends to weaken the coupling. Yet, even in the limit of high levels of noise in the replication times of the genes, both synthetic oscillators show clear signatures of locking to the cell cycle. This work enhances our understanding of the design of robust biological oscillators inside growing and diving cells.

  17. Phase dynamics of coupled oscillators reconstructed from data

    NASA Astrophysics Data System (ADS)

    Rosenblum, Michael; Kralemann, Bjoern; Pikovsky, Arkady

    2013-03-01

    We present a technique for invariant reconstruction of the phase dynamics equations for coupled oscillators from data. The invariant description is achieved by means of a transformation of phase estimates (protophases) obtained from general scalar observables to genuine phases. Staring from the bivariate data, we obtain the coupling functions in terms of these phases. We discuss the importance of the protophase-to-phase transformation for characterization of strength and directionality of interaction. To illustrate the technique we analyse the cardio-respiratory interaction on healthy humans. Our invariant approach is confirmed by high similarity of the coupling functions obtained from different observables of the cardiac system. Next, we generalize the technique to cover the case of small networks of coupled periodic units. We use the partial norms of the reconstructed coupling functions to quantify directed coupling between the oscillators. We illustrate the method by different network motifs for three coupled oscillators. We also discuss nonlinear effects in coupling.

  18. Synchronization of Coupled Mechanical Oscillators

    NASA Astrophysics Data System (ADS)

    Kennedy, Linda; Andereck, Barbara

    2007-10-01

    The Kuramoto model is used to describe synchronization of non-linear oscillators in biological, chemical, and physics systems. Using identical metronomes with similar frequencies on a movable platform, as per J. Pantaleone Am. J. Phys. 70, 992 (2002), we hope to realize a mechanical example of this model. A variety of materials were used for the movable platforms that coupled the metronomes. Platforms were either allowed to roll on cylindrical supports or suspended in pendulum fashion from the ceiling. Metronomes were started out of phase and allowed to synchronize. Measurements by PASCO photogates monitored by a LabView program were used to determine the phase difference between the two metronomes as a function of time. The dynamics of the metronome coupling was described by two second-order differential equations involving four key parameters: platform coupling, oscillation angle, damping/driving strength, and intrinsic frequency difference. Outstanding agreement between theory and experiment was achieved when the vertical motion of the platform and metronomes was included in the governing equations.

  19. Oscillations of a deformed liquid drop in an acoustic field

    NASA Astrophysics Data System (ADS)

    Shi, Tao; Apfel, Robert E.

    1995-07-01

    The oscillations of an axially symmetric liquid drop in an acoustic standing wave field in air have been studied using the boundary integral method. The interaction between the drop oscillation and sound field has been included in this analysis. Our computations focus on the frequency shift of small-amplitude oscillations of an acoustically deformed drop typical of a drop levitated in air. In the presence or absence of gravity, the trend and the magnitude of the frequency shift have been given in terms of drop size, drop deformation, and the strength of the sound field. Our calculations are compared with experiments performed on the United States Microgravity Laboratory (USML-1) and with ground-based measurements, and are found to be in good agreement within the accuracy of the experimental data.

  20. Jet Interactions in a Feedback-Free Fluidic Oscillator in the Transition Region

    NASA Astrophysics Data System (ADS)

    Tomac, Mehmet; Gregory, James

    2013-11-01

    The details of the jet interactions and oscillation mechanism of a feedback-free type fluidic oscillator are studied in this work. Flow rate-frequency measurements indicate the existence of three distinct operating regimes: low flow rate, transition, and high flow rate regions. This study presents results from the transition regime, extracted by using refractive index-matched particle image velocimetry (PIV). A newly-developed sensor configuration for frequency measurements in the refractive index-matched fluid and a phase-averaging method that minimizes jitter will be discussed. Experimental results indicate that the interactions of the two jets create three main vortices in the mixing chamber. One vortex vanishes and forms depending on the oscillation phase and plays a key role in the oscillation mechanism. The other two vortices sustain their existence throughout the oscillation cycle; however, both continuously change their size and strength. The resulting complex flow field with self-sustained oscillations is a result of the combination of many interesting phenomena such as jet interactions and bifurcations, viscous effects, vortex-shear layer interactions, vortex-wall interactions, instabilities, and saddle point creations.

  1. Differences in Vertical Structure of the Madden-Julian Oscillation Associated With the Quasi-Biennial Oscillation

    NASA Astrophysics Data System (ADS)

    Hendon, Harry H.; Abhik, S.

    2018-05-01

    The Madden-Julian Oscillation (MJO) during boreal winter is more active and propagates eastward farther into the western Pacific during the easterly phase of quasi-biennial oscillation (QBO). Using atmospheric reanalyses for 1980-2012, we show that the MJO-induced upper tropospheric positive temperature anomaly and overriding cold cap anomaly are stronger and more in-phase with the equatorial MJO-convective anomaly during the easterly phase of the QBO. These temperature anomalies combine to destabilize the upper troposphere more in-phase with MJO convection, thus acting to promote stronger MJO convection during the easterly phase of the QBO especially eastward of the Maritime Continent. This enhanced destabilization is promoted by the negative temperature anomaly at the tropopause resulting from the QBO during its easterly phase. These findings can account for the enhanced strength and farther eastward propagation of the MJO during the easterly phase of the QBO, but await confirmation by theoretical and modeling studies that can isolate these effects.

  2. Comparison of Three Methods of Assessing Muscle Strength and Imbalance Ratios of the Knee

    PubMed Central

    Moss, Crayton L.; Wright, P. Thomas

    1993-01-01

    Three strength measurement methods for determining muscle strength and imbalance ratios of the knee were compared in 41 (23 female, 18 male) NCAA Division I track and field athletes. Peak quadriceps extensions and hamstring flexions were measured isotonically, isometrically, and isokinetically. Isokinetic measurements were performed on a Cybex II at 60°/s. Isometric extension and flexion measurements were performed using the Nicholas Manual Muscle Tester (Lafayette Instruments; Lafayette, Ind). Isotonic measurements were done on both Universal and Nautilus apparatuses. Testing order was randomized to avoid a treatment order effect. A repeated measures ANOVA and a post hoc Tukey test were used to compare the three methods of assessing strength and imbalance ratios of the knee. Absolute strength values were significantly different according to gender and mode of testing. Bilateral strength imbalance ratios for knee flexion were significantly lower for the Nautilus leg curl machine. Ipsilateral strength imbalance ratios were significantly greater for the Cybex II. Our results indicated that absolute strength values cannot be interchanged between testing modes. Except for Cybex II (ipsilateral) and Nautilus (bilateral knee flexion), strength imbalance ratios could be interchanged. ImagesFig 1.Fig 2.Fig 3.Fig 4.Fig 5.Fig 6.Fig 7.INGING PMID:16558207

  3. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. © 2013 John Wiley & Sons Ltd.

  4. Measurements of temperature characteristics and estimation of terahertz negative differential conductance in resonant-tunneling-diode oscillators

    NASA Astrophysics Data System (ADS)

    Asada, M.; Suzuki, S.; Fukuma, T.

    2017-11-01

    The temperature dependences of output power, oscillation frequency, and current-voltage curve are measured for resonant-tunneling-diode terahertz (THz) oscillators. The output power largely changes with temperature owing to the change in Ohmic loss. In contrast to the output power, the oscillation frequency and current-voltage curve are almost insensitive to temperature. The measured temperature dependence of output power is compared with the theoretical calculation including the negative differential conductance (NDC) as a fitting parameter assumed to be independent of temperature. Very good agreement was obtained between the measurement and calculation, and the NDC in the THz frequency region is estimated. The results show that the absolute values of NDC in the THz region significantly decrease relative to that at DC, and increases with increasing frequency in the measured frequency range.

  5. Systematic determination of absolute absorption cross-section of individual carbon nanotubes

    PubMed Central

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B.; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G.; Wang, Enge; Wang, Feng

    2014-01-01

    Optical absorption is the most fundamental optical property characterizing light–matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

  6. Systematic determination of absolute absorption cross-section of individual carbon nanotubes.

    PubMed

    Liu, Kaihui; Hong, Xiaoping; Choi, Sangkook; Jin, Chenhao; Capaz, Rodrigo B; Kim, Jihoon; Wang, Wenlong; Bai, Xuedong; Louie, Steven G; Wang, Enge; Wang, Feng

    2014-05-27

    Optical absorption is the most fundamental optical property characterizing light-matter interactions in materials and can be most readily compared with theoretical predictions. However, determination of optical absorption cross-section of individual nanostructures is experimentally challenging due to the small extinction signal using conventional transmission measurements. Recently, dramatic increase of optical contrast from individual carbon nanotubes has been successfully achieved with a polarization-based homodyne microscope, where the scattered light wave from the nanostructure interferes with the optimized reference signal (the reflected/transmitted light). Here we demonstrate high-sensitivity absorption spectroscopy for individual single-walled carbon nanotubes by combining the polarization-based homodyne technique with broadband supercontinuum excitation in transmission configuration. To our knowledge, this is the first time that high-throughput and quantitative determination of nanotube absorption cross-section over broad spectral range at the single-tube level was performed for more than 50 individual chirality-defined single-walled nanotubes. Our data reveal chirality-dependent behaviors of exciton resonances in carbon nanotubes, where the exciton oscillator strength exhibits a universal scaling law with the nanotube diameter and the transition order. The exciton linewidth (characterizing the exciton lifetime) varies strongly in different nanotubes, and on average it increases linearly with the transition energy. In addition, we establish an empirical formula by extrapolating our data to predict the absorption cross-section spectrum for any given nanotube. The quantitative information of absorption cross-section in a broad spectral range and all nanotube species not only provides new insight into the unique photophysics in one-dimensional carbon nanotubes, but also enables absolute determination of optical quantum efficiencies in important

  7. Muscle Fiber Type Composition and Knee Extension Isometric Strength Fatigue Patterns in Power- and Endurance-Trained Males.

    ERIC Educational Resources Information Center

    Kroll, Walter; And Others

    1980-01-01

    There is a degree of uniqueness in fatigue patterns, particularly between different levels of absolute maximum strength. Caution should be used when analyzing fatigue curves among subjects with unspecified strength levels. (CJ)

  8. Generating macroscopic chaos in a network of globally coupled phase oscillators

    PubMed Central

    So, Paul; Barreto, Ernest

    2011-01-01

    We consider an infinite network of globally coupled phase oscillators in which the natural frequencies of the oscillators are drawn from a symmetric bimodal distribution. We demonstrate that macroscopic chaos can occur in this system when the coupling strength varies periodically in time. We identify period-doubling cascades to chaos, attractor crises, and horseshoe dynamics for the macroscopic mean field. Based on recent work that clarified the bifurcation structure of the static bimodal Kuramoto system, we qualitatively describe the mechanism for the generation of such complicated behavior in the time varying case. PMID:21974662

  9. Distinguishing Southern Africa precipitation response by strength of El Niño events

    NASA Astrophysics Data System (ADS)

    Pomposi, C.; Funk, C. C.; Shukla, S.; Magadzire, T.

    2017-12-01

    The El Niño Southern Oscillation (ENSO) is a leading mode of interannual precipitation variability and the main source of skill for seasonal climate predictions. Interannual precipitation variability linked to ENSO can have drastic impacts on agricultural systems and food resources in the semi-arid tropics, highlighting the need for increased information regarding ENSO's links to sub-seasonal to seasonal precipitation variations. The present work describes a case study on recent precipitation variability during warm ENSO events (i.e. El Niño) for the austral summer rainy season (December-February) in Southern Africa. Using a blending of observational and model data, it is found that the probability distribution of precipitation varies according to the strength of El Niño events. Strong El Niño events show a much clearer tendency for drying than moderate or weak events, which have smaller absolute magnitude anomalies and larger spatial heterogeneity in the precipitation response. A dynamical exploration of the various precipitation responses is also completed. The techniques utilized can be easily expanded to study likelihood of drought during El Niño for a variety of other regions and also provides information about El Niño strength and its influence on regional teleconnections. Finally, this presentation will describe the channels by which seasonal forecasting information is disseminated in the region and utilized by the Famine Early Warning Systems Network to help mitigate the impacts of potential food insecurity crises.

  10. Can the analyte-triggered asymmetric autocatalytic Soai reaction serve as a universal analytical tool for measuring enantiopurity and assigning absolute configuration?

    PubMed

    Welch, Christopher J; Zawatzky, Kerstin; Makarov, Alexey A; Fujiwara, Satoshi; Matsumoto, Arimasa; Soai, Kenso

    2016-12-20

    An investigation is reported on the use of the autocatalytic enantioselective Soai reaction, known to be influenced by the presence of a wide variety of chiral materials, as a generic tool for measuring the enantiopurity and absolute configuration of any substance. Good generality for the reaction across a small group of test analytes was observed, consistent with literature reports suggesting a diversity of compound types that can influence the stereochemical outcome of this reaction. Some trends in the absolute sense of stereochemical enrichment were noted, suggesting the possible utility of the approach for assigning absolute configuration to unknown compounds, by analogy to closely related species with known outcomes. Considerable variation was observed in the triggering strength of different enantiopure materials, an undesirable characteristic when dealing with mixtures containing minor impurities with strong triggering strength in the presence of major components with weak triggering strength. A strong tendency of the reaction toward an 'all or none' type of behavior makes the reaction most sensitive for detecting enantioenrichment close to zero. Consequently, the ability to discern modest from excellent enantioselectivity was relatively poor. While these properties limit the ability to obtain precise enantiopurity measurements in a simple single addition experiment, prospects may exist for more complex experimental setups that may potentially offer improved performance.

  11. Gamma oscillation maintains stimulus structure-dependent synchronization in cat visual cortex.

    PubMed

    Samonds, Jason M; Bonds, A B

    2005-01-01

    Visual cortical cells demonstrate both oscillation and synchronization, although the underlying causes and functional significance of these behaviors remain uncertain. We simultaneously recorded single-unit activity with microelectrode arrays in supragranular layers of area 17 of cats paralyzed and anesthetized with propofol and N(2)O. Rate-normalized autocorrelograms of 24 cells reveal bursting (100%) and gamma oscillation (63%). Renewal density analysis, used to explore the source of oscillation, suggests a contribution from extrinsic influences such as feedback. However, a bursting refractory period, presumably membrane-based, could also encourage oscillatory firing. When we investigated the source of synchronization for 60 cell pairs we found only moderate correlation of synchrony with bursts and oscillation. We did, nonetheless, discover a possible functional role for oscillation. In all cases of cross-correlograms that exhibited oscillation, the strength of the synchrony was maintained throughout the stimulation period. When no oscillation was apparent, 75% of the cell pairs showed decay in their synchronization. The synchrony between cells is strongly dependent on similar response onset latencies. We therefore propose that structured input, which yields tight organization of latency, is a more likely candidate for the source of synchronization than oscillation. The reliable synchrony at response onset could be driven by spatial and temporal correlation of the stimulus that is preserved through the earlier stages of the visual system. Oscillation then contributes to maintenance of the synchrony to enhance reliable transmission of the information for higher cognitive processing.

  12. Handgrip Strength and Ideal Cardiovascular Health among Colombian Children and Adolescents.

    PubMed

    Ramírez-Vélez, Robinson; Tordecilla-Sanders, Alejandra; Correa-Bautista, Jorge Enrique; Peterson, Mark D; Garcia-Hermoso, Antonio

    2016-12-01

    To evaluate the association between handgrip strength and ideal cardiovascular health (CVH) in Colombian children and adolescents. During the 2014-2015 school years, we examined a cross-sectional component of the FUPRECOL (Association for Muscular Strength with Early Manifestation of Cardiovascular Disease Risk Factors among Colombian Children and Adolescents) study. Participants included 1199 (n = 627 boys) youths from Bogota (Colombia). Handgrip strength was measured with a standard adjustable hand held dynamometer and expressed relative to body mass (handgrip/body mass) and as absolute values in kilograms. Ideal CVH, as defined by the American Heart Association, was determined as meeting ideal levels of the following components: 4 behaviors (smoking status, body mass index, cardiorespiratory fitness, and diet) and 3 factors (total cholesterol, blood pressure, and glucose). Higher levels of handgrip strength (both absolute and relative values) were associated with a higher frequency of ideal CVH metrics in both sexes (P for trend ≤ .001). Also, higher levels of handgrip strength were associated with a greater number of ideal health behaviors (P for trend < .001 in both boys and girls), and with a higher number of ideal health factors in boys (P for trend < .001). Finally, levels of handgrip strength were similar between ideal versus nonideal glucose or total cholesterol groups in girls. Handgrip strength was strongly associated with ideal CVH in Colombian children and adolescents, and thus supports the relevance of early targeted interventions to promote strength adaptation and preservation as part of primordial prevention. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Landau levels and magnetic oscillations in gapped Dirac materials with intrinsic Rashba interaction

    NASA Astrophysics Data System (ADS)

    Tsaran, V. Yu.; Sharapov, S. G.

    2014-11-01

    A new family of the low-buckled Dirac materials which includes silicene, germanene, etc. is expected to possess a more complicated sequence of Landau levels than in pristine graphene. Their energies depend, among other factors, on the strength of the intrinsic spin-orbit (SO) and Rashba SO couplings and can be tuned by an applied electric field Ez. We studied the influence of the intrinsic Rashba SO term on the energies of Landau levels using both analytical and numerical methods. The quantum magnetic oscillations of the density of states are also investigated. A specific feature of the oscillations is the presence of the beats with the frequency proportional to the field Ez. The frequency of the beats becomes also dependent on the carrier concentration when Rashba interaction is present allowing experimental determination of its strength.

  14. Reviving oscillations in coupled nonlinear oscillators.

    PubMed

    Zou, Wei; Senthilkumar, D V; Zhan, Meng; Kurths, Jürgen

    2013-07-05

    By introducing a processing delay in the coupling, we find that it can effectively annihilate the quenching of oscillation, amplitude death (AD), in a network of coupled oscillators by switching the stability of AD. It revives the oscillation in the AD regime to retain sustained rhythmic functioning of the networks, which is in sharp contrast to the propagation delay with the tendency to induce AD. This processing delay-induced phenomenon occurs both with and without the propagation delay. Further this effect is rather general from two coupled to networks of oscillators in all known scenarios that can exhibit AD, and it has a wide range of applications where sustained oscillations should be retained for proper functioning of the systems.

  15. Investigating the Control of Ocean-Atmospheric Oscillations on Global Terrestrial Evaporation

    NASA Astrophysics Data System (ADS)

    Martens, B.; Waegeman, W.; Dorigo, W.; Verhoest, N.; Miralles, D. G.

    2017-12-01

    Intra-annual and multi-decadal variability in Earth's climate is strongly driven by periodic oscillations in the coupled state of our atmosphere and ocean. These oscillations do not only impact climate in nearby regions, but can also have an effect on the climate in remote areas, a phenomenon that is often referred to as teleconnection. Because changes in local climate immediately affect terrestrial ecosystems through a series of complex processes, ocean-atmospheric oscillations are expected to influence land evaporation; i.e. the return flux of water from land into the atmosphere. In this presentation, the effects of ocean-atmospheric oscillations on global terrestrial evaporation are analysed. We use multi-decadal, satellite-based observations of different climate variables (air temperature, radiation, precipitation) in combination with a simple supervised learning method - the Least Absolute Shrinkage and Selection Operator - to detect the impact of sixteen leading ocean-atmospheric oscillations on terrestrial evaporation. The latter is retrieved using the Global Land Evaporation Amsterdam Model (GLEAM). The analysis reveals hotspot regions in which more than 30% of the inter-annual variability in terrestrial evaporation can be explained by ocean-atmospheric oscillations. The impact is different per region and season, and can typically be attributed to a small subset of oscillations. For instance, the dynamics in terrestrial evaporation over eastern Australia are substantially impacted by both the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) during Austral spring. Using the same learning method, but targeting terrestrial evaporation based on its local climatic drivers (air temperature, precipitation, and radiation), shows the dominant control of precipitation on terrestrial evaporation in Australia, suggesting that both ENSO and IOD affect the precipitation, in his turn influencing evaporation. The latter is confirmed by regressing

  16. GONG Catalog of Solar Filament Oscillations Near Solar Maximum

    NASA Astrophysics Data System (ADS)

    Luna, M.; Karpen, J.; Ballester, J. L.; Muglach, K.; Terradas, J.; Kucera, T.; Gilbert, H.

    2018-06-01

    We have cataloged 196 filament oscillations from the Global Oscillation Network Group Hα network data during several months near the maximum of solar cycle 24 (2014 January–June). Selected examples from the catalog are described in detail, along with our statistical analyses of all events. Oscillations were classified according to their velocity amplitude: 106 small-amplitude oscillations (SAOs), with velocities <10 {km} {{{s}}}-1, and 90 large-amplitude oscillations (LAOs), with velocities >10 {km} {{{s}}}-1. Both SAOs and LAOs are common, with one event of each class every two days on the visible side of the Sun. For nearly half of the events, we identified their apparent trigger. The period distribution has a mean value of 58 ± 15 minutes for both types of oscillations. The distribution of the damping time per period peaks at τ/P = 1.75 and 1.25 for SAOs and LAOs, respectively. We confirmed that LAO damping rates depend nonlinearly on the oscillation velocity. The angle between the direction of motion and the filament spine has a distribution centered at 27° for all filament types. This angle agrees with the observed direction of filament-channel magnetic fields, indicating that most of the cataloged events are longitudinal (i.e., undergo field-aligned motions). We applied seismology to determine the average radius of curvature in the magnetic dips, R ≈ 89 Mm, and the average minimum magnetic field strength, B ≈ 16 G. The catalog is available to the community online and is intended to be expanded to cover at least 1 solar cycle.

  17. Control of coupled oscillator networks with application to microgrid technologies.

    PubMed

    Skardal, Per Sebastian; Arenas, Alex

    2015-08-01

    The control of complex systems and network-coupled dynamical systems is a topic of vital theoretical importance in mathematics and physics with a wide range of applications in engineering and various other sciences. Motivated by recent research into smart grid technologies, we study the control of synchronization and consider the important case of networks of coupled phase oscillators with nonlinear interactions-a paradigmatic example that has guided our understanding of self-organization for decades. We develop a method for control based on identifying and stabilizing problematic oscillators, resulting in a stable spectrum of eigenvalues, and in turn a linearly stable synchronized state. The amount of control, that is, number of oscillators, required to stabilize the network is primarily dictated by the coupling strength, dynamical heterogeneity, and mean degree of the network, and depends little on the structural heterogeneity of the network itself.

  18. Control of coupled oscillator networks with application to microgrid technologies

    NASA Astrophysics Data System (ADS)

    Arenas, Alex

    The control of complex systems and network-coupled dynamical systems is a topic of vital theoretical importance in mathematics and physics with a wide range of applications in engineering and various other sciences. Motivated by recent research into smart grid technologies, we study the control of synchronization and consider the important case of networks of coupled phase oscillators with nonlinear interactions-a paradigmatic example that has guided our understanding of self-organization for decades. We develop a method for control based on identifying and stabilizing problematic oscillators, resulting in a stable spectrum of eigenvalues, and in turn a linearly stable syn- chronized state. The amount of control, that is, number of oscillators, required to stabilize the network is primarily dictated by the coupling strength, dynamical heterogeneity, and mean degree of the network, and depends little on the structural heterogeneity of the network itself.

  19. Oscillating-Linear-Drive Vacuum Compressor for CO2

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Shimko, Martin

    2005-01-01

    A vacuum compressor has been designed to compress CO2 from approximately equal to 1 psia (approximately equal to 6.9 kPa absolute pressure) to approximately equal to 75 psia (approximately equal to 0.52 MPa), to be insensitive to moisture, to have a long operational life, and to be lightweight, compact, and efficient. The compressor consists mainly of (1) a compression head that includes hydraulic diaphragms, a gas-compression diaphragm, and check valves; and (2) oscillating linear drive that includes a linear motor and a drive spring, through which compression force is applied to the hydraulic diaphragms. The motor is driven at the resonance vibrational frequency of the motor/spring/compression-head system, the compression head acting as a damper that takes energy out of the oscillation. The net effect of the oscillation is to cause cyclic expansion and contraction of the gas-compression diaphragm, and, hence, of the volume bounded by this diaphragm. One-way check valves admit gas into this volume from the low-pressure side during expansion and allow the gas to flow out to the high-pressure side during contraction. Fatigue data and the results of diaphragm stress calculations have been interpreted as signifying that the compressor can be expected to have an operational life of greater than 30 years with a confidence level of 99.9 percent.

  20. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed.

  1. Slow oscillation amplitudes and up-state lengths relate to memory improvement.

    PubMed

    Heib, Dominik P J; Hoedlmoser, Kerstin; Anderer, Peter; Zeitlhofer, Josef; Gruber, Georg; Klimesch, Wolfgang; Schabus, Manuel

    2013-01-01

    There is growing evidence of the active involvement of sleep in memory consolidation. Besides hippocampal sharp wave-ripple complexes and sleep spindles, slow oscillations appear to play a key role in the process of sleep-associated memory consolidation. Furthermore, slow oscillation amplitude and spectral power increase during the night after learning declarative and procedural memory tasks. However, it is unresolved whether learning-induced changes specifically alter characteristics of individual slow oscillations, such as the slow oscillation up-state length and amplitude, which are believed to be important for neuronal replay. 24 subjects (12 men) aged between 20 and 30 years participated in a randomized, within-subject, multicenter study. Subjects slept on three occasions for a whole night in the sleep laboratory with full polysomnography. Whereas the first night only served for adaptation purposes, the two remaining nights were preceded by a declarative word-pair task or by a non-learning control task. Slow oscillations were detected in non-rapid eye movement sleep over electrode Fz. Results indicate positive correlations between the length of the up-state as well as the amplitude of both slow oscillation phases and changes in memory performance from pre to post sleep. We speculate that the prolonged slow oscillation up-state length might extend the timeframe for the transfer of initial hippocampal to long-term cortical memory representations, whereas the increase in slow oscillation amplitudes possibly reflects changes in the net synaptic strength of cortical networks.

  2. Absolute dual-comb spectroscopy at 1.55 μm by free-running Er:fiber lasers

    NASA Astrophysics Data System (ADS)

    Cassinerio, Marco; Gambetta, Alessio; Coluccelli, Nicola; Laporta, Paolo; Galzerano, Gianluca

    2014-06-01

    We report on a compact scheme for absolute referencing and coherent averaging for dual-comb based spectrometers, exploiting a single continuous-wave (CW) laser in a transfer oscillator configuration. The same CW laser is used for both absolute calibration of the optical frequency axis and the generation of a correction signal which is used for a real-time jitter compensation in a fully electrical feed-forward scheme. The technique is applied to a near-infrared spectrometer based on a pair of free-running mode-locked Er:fiber lasers, allowing to perform real-time absolute-frequency measurements over an optical bandwidth of more than 25 nm, with coherent interferogram averaging over 1-s acquisition time, leading to a signal-to-noise ratio improvement of 29 dB over the 50 μs single shot acquisition. Using 10-cm single pass cell, a value of 1.9 × 10-4 cm-1 Hz-0.5 noise-equivalent-absorption over 1 s integration time is obtained, which can be further scaled down with a multi-pass or resonant cavity. The adoption of a single CW laser, together with the absence of optical locks, and the full-fiber design makes this spectrometer a robust and compact system to be employed in gas-sensing applications.

  3. Quasi-periodic oscillations in superfluid, relativistic magnetars with nuclear pasta phases

    NASA Astrophysics Data System (ADS)

    Passamonti, Andrea; Pons, José A.

    2016-12-01

    We study the torsional magneto-elastic oscillations of relativistic superfluid magnetars and explore the effects of a phase transition in the crust-core interface (nuclear pasta) which results in a weaker elastic response. Exploring various models with different extension of nuclear pasta phases, we find that the differences in the oscillation spectrum present in purely elastic modes (weak magnetic field) are smeared out with increasing strength of the magnetic field. For magnetar conditions, the main characteristic and features of models without nuclear pasta are preserved. We find, in general, two classes of magneto-elastic oscillations which exhibit a different oscillation pattern. For Bp < 4 × 1014 G, the spectrum is characterized by the turning points and edges of the continuum which are mostly confined into the star's core, and have no constant phase. Increasing the magnetic field, we find, in addition, several magneto-elastic oscillations which reach the surface and have an angular structure similar to crustal modes. These global magneto-elastic oscillations show a constant phase and become dominant when Bp > 5 × 1014 G. We do not find any evidence of fundamental pure crustal modes in the low-frequency range (below 200 Hz) for Bp ≥ 1014 G.

  4. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  5. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K [Pleasanton, CA; Snyderman, Neal J [Berkeley, CA; Rowland, Mark S [Alamo, CA

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  6. Multiple mechanisms switch an electrically coupled, synaptically inhibited neuron between competing rhythmic oscillators.

    PubMed

    Gutierrez, Gabrielle J; O'Leary, Timothy; Marder, Eve

    2013-03-06

    Rhythmic oscillations are common features of nervous systems. One of the fundamental questions posed by these rhythms is how individual neurons or groups of neurons are recruited into different network oscillations. We modeled competing fast and slow oscillators connected to a hub neuron with electrical and inhibitory synapses. We explore the patterns of coordination shown in the network as a function of the electrical coupling and inhibitory synapse strengths with the help of a novel visualization method that we call the "parameterscape." The hub neuron can be switched between the fast and slow oscillators by multiple network mechanisms, indicating that a given change in network state can be achieved by degenerate cellular mechanisms. These results have importance for interpreting experiments employing optogenetic, genetic, and pharmacological manipulations to understand circuit dynamics. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Space qualified hybrid superconductor/semiconductor planar oscillator circuit

    NASA Technical Reports Server (NTRS)

    Miranda, F. A.; Chorey, C. M.; Romanofsky, R. R.; Bhasin, K. B.

    1995-01-01

    We report on the space qualification of a hybrid superconductor/semiconductor planar local oscillator (LO) at 8.4 GHz. This oscillator was designed, fabricated, and tested as a component for the High Temperature Superconductivity Space Experiment 2 (HTSSE-2). The LO consisted of a GaAs MESFET and microstrip circuitry patterned onto a YBa2Cu3O(7-delta) high temperature superconducting (HTS) thin film on a 1.0 x 1.0 sq cm lanthanum aluminate (LaAlO3) substrate. At 77 K, this oscillator achieved power output levels up to 10 dBm into a 50 Ohm load. When incorporated into a full cryogenic receiver, the LO provided output powers within 0.0-3.0 dBm with less than 50 mW of dc power dissipation. Space qualification data on the sensitivity of the HTS films to the processing steps involved in the fabrication of HTS-based components are presented. Data on ohmic contacts, strength of wire bonds made to such contacts, and aging effects as well as vibration test results are discussed.

  8. Realized volatility and absolute return volatility: a comparison indicating market risk.

    PubMed

    Zheng, Zeyu; Qiao, Zhi; Takaishi, Tetsuya; Stanley, H Eugene; Li, Baowen

    2014-01-01

    Measuring volatility in financial markets is a primary challenge in the theory and practice of risk management and is essential when developing investment strategies. Although the vast literature on the topic describes many different models, two nonparametric measurements have emerged and received wide use over the past decade: realized volatility and absolute return volatility. The former is strongly favored in the financial sector and the latter by econophysicists. We examine the memory and clustering features of these two methods and find that both enable strong predictions. We compare the two in detail and find that although realized volatility has a better short-term effect that allows predictions of near-future market behavior, absolute return volatility is easier to calculate and, as a risk indicator, has approximately the same sensitivity as realized volatility. Our detailed empirical analysis yields valuable guidelines for both researchers and market participants because it provides a significantly clearer comparison of the strengths and weaknesses of the two methods.

  9. Realized Volatility and Absolute Return Volatility: A Comparison Indicating Market Risk

    PubMed Central

    Takaishi, Tetsuya; Stanley, H. Eugene; Li, Baowen

    2014-01-01

    Measuring volatility in financial markets is a primary challenge in the theory and practice of risk management and is essential when developing investment strategies. Although the vast literature on the topic describes many different models, two nonparametric measurements have emerged and received wide use over the past decade: realized volatility and absolute return volatility. The former is strongly favored in the financial sector and the latter by econophysicists. We examine the memory and clustering features of these two methods and find that both enable strong predictions. We compare the two in detail and find that although realized volatility has a better short-term effect that allows predictions of near-future market behavior, absolute return volatility is easier to calculate and, as a risk indicator, has approximately the same sensitivity as realized volatility. Our detailed empirical analysis yields valuable guidelines for both researchers and market participants because it provides a significantly clearer comparison of the strengths and weaknesses of the two methods. PMID:25054439

  10. A NEW CLINICAL MUSCLE FUNCTION TEST FOR ASSESSMENT OF HIP EXTERNAL ROTATION STRENGTH: AUGUSTSSON STRENGTH TEST.

    PubMed

    Augustsson, Jesper

    2016-08-01

    Dynamic clinical tests of hip strength applicable on patients, non-athletes and athletes alike, are lacking. The aim of this study was therefore to develop and evaluate the reliability of a dynamic muscle function test of hip external rotation strength, using a novel device. A second aim was to determine if gender differences exist in absolute and relative hip strength using the new test. Fifty-three healthy sport science students (34 women and 19 men) were tested for hip external rotation strength using a device that consisted of a strap connected in series with an elastic resistance band loop, and a measuring tape connected in parallel with the elastic resistance band. The test was carried out with the subject side lying, positioned in 45 ° of hip flexion and the knees flexed to 90 ° with the device firmly fastened proximally across the knees. The subject then exerted maximal concentric hip external rotation force against the device thereby extending the elastic resistance band. The displacement achieved by the subject was documented by the tape measure and the corresponding force production was calculated. Both right and left hip strength was measured. Fifteen of the subjects were tested on repeated occasions to evaluate test-retest reliability. No significant test-retest differences were observed. Intra-class correlation coefficients ranged 0.93-0.94 and coefficients of variation 2.76-4.60%. In absolute values, men were significantly stronger in hip external rotation than women (right side 13.2 vs 11.0 kg, p = 0.001, left side 13.2 vs 11.5 kg, p = 0.002). There were no significant differences in hip external rotation strength normalized for body weight (BW) between men and women (right side 0.17 kg/BW vs 0.17 kg/BW, p = 0.675, left side 0.17 kg/BW vs 0.18 kg/BW, p = 0.156). The new muscle function test showed high reliability and thus could be useful for measuring dynamic hip external rotation strength in patients, non-athletes and athletes

  11. The Absolute Stability Analysis in Fuzzy Control Systems with Parametric Uncertainties and Reference Inputs

    NASA Astrophysics Data System (ADS)

    Wu, Bing-Fei; Ma, Li-Shan; Perng, Jau-Woei

    This study analyzes the absolute stability in P and PD type fuzzy logic control systems with both certain and uncertain linear plants. Stability analysis includes the reference input, actuator gain and interval plant parameters. For certain linear plants, the stability (i.e. the stable equilibriums of error) in P and PD types is analyzed with the Popov or linearization methods under various reference inputs and actuator gains. The steady state errors of fuzzy control systems are also addressed in the parameter plane. The parametric robust Popov criterion for parametric absolute stability based on Lur'e systems is also applied to the stability analysis of P type fuzzy control systems with uncertain plants. The PD type fuzzy logic controller in our approach is a single-input fuzzy logic controller and is transformed into the P type for analysis. In our work, the absolute stability analysis of fuzzy control systems is given with respect to a non-zero reference input and an uncertain linear plant with the parametric robust Popov criterion unlike previous works. Moreover, a fuzzy current controlled RC circuit is designed with PSPICE models. Both numerical and PSPICE simulations are provided to verify the analytical results. Furthermore, the oscillation mechanism in fuzzy control systems is specified with various equilibrium points of view in the simulation example. Finally, the comparisons are also given to show the effectiveness of the analysis method.

  12. Control of coupled oscillator networks with application to microgrid technologies

    PubMed Central

    Skardal, Per Sebastian; Arenas, Alex

    2015-01-01

    The control of complex systems and network-coupled dynamical systems is a topic of vital theoretical importance in mathematics and physics with a wide range of applications in engineering and various other sciences. Motivated by recent research into smart grid technologies, we study the control of synchronization and consider the important case of networks of coupled phase oscillators with nonlinear interactions—a paradigmatic example that has guided our understanding of self-organization for decades. We develop a method for control based on identifying and stabilizing problematic oscillators, resulting in a stable spectrum of eigenvalues, and in turn a linearly stable synchronized state. The amount of control, that is, number of oscillators, required to stabilize the network is primarily dictated by the coupling strength, dynamical heterogeneity, and mean degree of the network, and depends little on the structural heterogeneity of the network itself. PMID:26601231

  13. Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

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

    Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt; Department of Physics, Sophia University, Tokyo 102-8554; Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA

    2015-02-14

    The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ({sup 1}Δ←{sup 1}Σ{sup +}) transition, with a new weak transition assigned to ({sup 1}Σ{sup −}←{sup 1}Σ{sup +}) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to {sup 1}Σ{sup +} and {sup 1}Πmore » transitions. Based on our recent measurements of differential cross sections for the optically allowed ({sup 1}Σ{sup +} and {sup 1}Π) transitions of COS by electron impact, the optical oscillator strength f{sub 0} value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km)« less

  14. Optimal estimation of the optomechanical coupling strength

    NASA Astrophysics Data System (ADS)

    Bernád, József Zsolt; Sanavio, Claudio; Xuereb, André

    2018-06-01

    We apply the formalism of quantum estimation theory to obtain information about the value of the nonlinear optomechanical coupling strength. In particular, we discuss the minimum mean-square error estimator and a quantum Cramér-Rao-type inequality for the estimation of the coupling strength. Our estimation strategy reveals some cases where quantum statistical inference is inconclusive and merely results in the reinforcement of prior expectations. We show that these situations also involve the highest expected information losses. We demonstrate that interaction times on the order of one time period of mechanical oscillations are the most suitable for our estimation scenario, and compare situations involving different photon and phonon excitations.

  15. A Measurement of the Absolute Reactor Antineutrino Flux and Spectrum at Daya Bay

    NASA Astrophysics Data System (ADS)

    An, Fengpeng

    2017-12-01

    The Daya Bay Reactor Neutrino Experiment uses an array of eight underground detectors to study antineutrinos from six reactor cores with different baselines. Since the start of data-taking from late 2011, Daya Bay has collected the largest sample of reactor antineutrino events to date, and has made the most precise measurement of the neutrino oscillation parameters sin22θ13 and Δm2ee. Using the data from the four detectors in the near experimental halls, Daya Bay has made a high statistics measurement of the absolute reactor antineutrino flux and spectrum. In this paper we will present this measurement and its comparison to predictions based on different flux models.

  16. Self-oscillation

    NASA Astrophysics Data System (ADS)

    Jenkins, Alejandro

    2013-04-01

    Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.

  17. Simultaneous Sea-Level Oscillations in Japanese Bays Induced by the Tsunami of Nankai-Trough Earthquake

    NASA Astrophysics Data System (ADS)

    Oishi, Y.; Furumura, T.; Imamura, F.; Yamashita, K.; Sugawara, D.

    2016-12-01

    In this study, we investigate the response of bays to the tsunami of Nankai-trough earthquake based on tsunami simulations and demonstrate the possibility that sea-level oscillation of each bay, which is induced by an incident tsunami, interacts with those of other bays. Several major cities in Japan, including the capital, are located in the bays near the Nankai trough and it is assumed that these cities will be largely affected by the tsunamis caused by recurring large earthquakes at the trough. Therefore, it is very important for these populated cities to understand the mechanism and properties of the tsunami-induced oscillations that continue for a long time in bays to draw up evacuation plans. To investigate the response of bays for various tsunamis that may occur in the Nankai trough area, we distributed the tsunami sources that have the form of a 2-D Gaussian function around the Nankai trough. From simulations with these sources, it was found that strong oscillations of bay water occur when the source is located in the bay itself or when strong oscillations occur in other bays. For example, when the Tosa bay oscillates, the Tokyo bay that is 600 km away from the Tosa bay also oscillates. Among the bays around the Nankai trough, the Suruga bay, the deepest bay in Japan with a 2500-km depth, oscillates more strongly than other bays for most cases. To check the influence of the strong oscillations in the Suruga bay on other bays, we conducted tsunami simulations using a modified topography model in which the Suruga bay is artificially landfilled. As a consequence, the strength of oscillations in the adjacent bays are reduced by 20-30%, suggesting the large influence of the distinguished oscillation of the Suruga bay on these bays. We finally conducted tsunami simulations using the eleven Nankai-trough earthquake scenarios of the Central Disaster Prevention Council (CDPC) of Japan as tsunami sources, and the mutual relation regarding the strengths of

  18. Modeling of Compressive Strength for Self-Consolidating High-Strength Concrete Incorporating Palm Oil Fuel Ash

    PubMed Central

    Safiuddin, Md.; Raman, Sudharshan N.; Abdus Salam, Md.; Jumaat, Mohd. Zamin

    2016-01-01

    Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable mathematical models for the prediction of compressive strength of different concretes, but not for self-consolidating high-strength concrete (SCHSC) containing palm oil fuel ash (POFA). The present study has used artificial neural networks (ANN) to predict the compressive strength of SCHSC incorporating POFA. The ANN model has been developed and validated in this research using the mix proportioning and experimental strength data of 20 different SCHSC mixes. Seventy percent (70%) of the data were used to carry out the training of the ANN model. The remaining 30% of the data were used for testing the model. The training of the ANN model was stopped when the root mean square error (RMSE) and the percentage of good patterns was 0.001 and ≈100%, respectively. The predicted compressive strength values obtained from the trained ANN model were much closer to the experimental values of compressive strength. The coefficient of determination (R2) for the relationship between the predicted and experimental compressive strengths was 0.9486, which shows the higher degree of accuracy of the network pattern. Furthermore, the predicted compressive strength was found very close to the experimental compressive strength during the testing process of the ANN model. The absolute and percentage relative errors in the testing process were significantly low with a mean value of 1.74 MPa and 3.13%, respectively, which indicated that the compressive strength of SCHSC including POFA can be efficiently predicted by the ANN. PMID:28773520

  19. Modeling of Compressive Strength for Self-Consolidating High-Strength Concrete Incorporating Palm Oil Fuel Ash.

    PubMed

    Safiuddin, Md; Raman, Sudharshan N; Abdus Salam, Md; Jumaat, Mohd Zamin

    2016-05-20

    Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable mathematical models for the prediction of compressive strength of different concretes, but not for self-consolidating high-strength concrete (SCHSC) containing palm oil fuel ash (POFA). The present study has used artificial neural networks (ANN) to predict the compressive strength of SCHSC incorporating POFA. The ANN model has been developed and validated in this research using the mix proportioning and experimental strength data of 20 different SCHSC mixes. Seventy percent (70%) of the data were used to carry out the training of the ANN model. The remaining 30% of the data were used for testing the model. The training of the ANN model was stopped when the root mean square error (RMSE) and the percentage of good patterns was 0.001 and ≈100%, respectively. The predicted compressive strength values obtained from the trained ANN model were much closer to the experimental values of compressive strength. The coefficient of determination ( R ²) for the relationship between the predicted and experimental compressive strengths was 0.9486, which shows the higher degree of accuracy of the network pattern. Furthermore, the predicted compressive strength was found very close to the experimental compressive strength during the testing process of the ANN model. The absolute and percentage relative errors in the testing process were significantly low with a mean value of 1.74 MPa and 3.13%, respectively, which indicated that the compressive strength of SCHSC including POFA can be efficiently predicted by the ANN.

  20. Small-amplitude oscillations of electrostatically levitated drops

    NASA Astrophysics Data System (ADS)

    Feng, J. Q.; Beard, K. V.

    1990-07-01

    The nature of axisymmetric oscillations of electrostatically levitated drops is examined using an analytical method of multiple-parameter perturbations. The solution for the quiescent equilibrium shape exhibits both stretching of the drop surface along the direction of the externally applied electric field and asymmetry about the drop's equatorial plane. In the presence of electric and gravitational fields, small-amplitude oscillations of charged drops differ from the linear modes first analyzed by Rayleigh. The oscillatory response at each frequency consists of several Legendre polynomials rather than just one, and the characteristic frequency for each axisymmetric mode decreases from that calculated by Rayleigh as the electric field strength increases. This lowering of the characteristic frequencies is enhanced by the net electric charge required for levitation against gravity. Since the contributions of the various forces appear explicitly in the analytic solutions, physical insight is readily gained into their causative role in drop behavior.

  1. Intermittent and sustained periodic windows in networked chaotic Rössler oscillators

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

    He, Zhiwei; Sun, Yong; University of the Chinese Academy of Sciences, Beijing 100049

    Route to chaos (or periodicity) in dynamical systems is one of fundamental problems. Here, dynamical behaviors of coupled chaotic Rössler oscillators on complex networks are investigated and two different types of periodic windows with the variation of coupling strength are found. Under a moderate coupling, the periodic window is intermittent, and the attractors within the window extremely sensitively depend on the initial conditions, coupling parameter, and topology of the network. Therefore, after adding or removing one edge of network, the periodic attractor can be destroyed and substituted by a chaotic one, or vice versa. In contrast, under an extremely weakmore » coupling, another type of periodic window appears, which insensitively depends on the initial conditions, coupling parameter, and network. It is sustained and unchanged for different types of network structure. It is also found that the phase differences of the oscillators are almost discrete and randomly distributed except that directly linked oscillators more likely have different phases. These dynamical behaviors have also been generally observed in other networked chaotic oscillators.« less

  2. New type of chimera structures in a ring of bistable FitzHugh-Nagumo oscillators with nonlocal interaction

    NASA Astrophysics Data System (ADS)

    Shepelev, I. A.; Vadivasova, T. E.; Bukh, A. V.; Strelkova, G. I.; Anishchenko, V. S.

    2017-04-01

    We study the spatiotemporal dynamics of a ring of nonlocally coupled FitzHugh-Nagumo oscillators in the bistable regime. A new type of chimera patterns has been found in the noise-free network and when isolated elements do not oscillate. The region of existence of these structures has been explored when the coupling range and the coupling strength between the network elements are varied.

  3. Network properties of interstitial cells of Cajal affect intestinal pacemaker activity and motor patterns, according to a mathematical model of weakly coupled oscillators.

    PubMed

    Wei, Ruihan; Parsons, Sean P; Huizinga, Jan D

    2017-03-01

    What is the central question of this study? What are the effects of interstitial cells of Cajal (ICC) network perturbations on intestinal pacemaker activity and motor patterns? What is the main finding and its importance? Two-dimensional modelling of the ICC pacemaker activity according to a phase model of weakly coupled oscillators showed that network properties (coupling strength between oscillators, frequency gradient and frequency noise) strongly influence pacemaker network activity and subsequent motor patterns. The model explains motor patterns observed in physiological conditions and provides predictions and testable hypotheses for effects of ICC loss and frequency modulation on the motor patterns. Interstitial cells of Cajal (ICC) are the pacemaker cells of gut motility and are associated with motility disorders. Interstitial cells of Cajal form a network, but the contributions of its network properties to gut physiology and dysfunction are poorly understood. We modelled an ICC network as a two-dimensional network of weakly coupled oscillators with a frequency gradient and showed changes over time in video and graphical formats. Model parameters were obtained from slow-wave-driven contraction patterns in the mouse intestine and pacemaker slow-wave activities from the cat intestine. Marked changes in propagating oscillation patterns (including changes from propagation to non-propagating) were observed by changing network parameters (coupling strength between oscillators, the frequency gradient and frequency noise), which affected synchronization, propagation velocity and occurrence of dislocations (termination of an oscillation). Complete uncoupling of a circumferential ring of oscillators caused the proximal and distal section to desynchronize, but complete synchronization was maintained with only a single oscillator connecting the sections with high enough coupling. The network of oscillators could withstand loss; even with 40% of oscillators lost randomly

  4. Chimera at the phase-flip transition of an ensemble of identical nonlinear oscillators

    NASA Astrophysics Data System (ADS)

    Gopal, R.; Chandrasekar, V. K.; Senthilkumar, D. V.; Venkatesan, A.; Lakshmanan, M.

    2018-06-01

    A complex collective emerging behavior characterized by coexisting coherent and incoherent domains is termed as a chimera state. We bring out the existence of a new type of chimera in a nonlocally coupled ensemble of identical oscillators driven by a common dynamic environment. The latter facilitates the onset of phase-flip bifurcation/transitions among the coupled oscillators of the ensemble, while the nonlocal coupling induces a partial asynchronization among the out-of-phase synchronized oscillators at this onset. This leads to the manifestation of coexisting out-of-phase synchronized coherent domains interspersed by asynchronous incoherent domains elucidating the existence of a different type of chimera state. In addition to this, a rich variety of other collective behaviors such as clusters with phase-flip transition, conventional chimera, solitary state and complete synchronized state which have been reported using different coupling architectures are found to be induced by the employed couplings for appropriate coupling strengths. The robustness of the resulting dynamics is demonstrated in ensembles of two paradigmatic models, namely Rössler oscillators and Stuart-Landau oscillators.

  5. Measurement of ultra-low power oscillators using adaptive drift cancellation with applications to nano-magnetic spin torque oscillators.

    PubMed

    Tamaru, S; Ricketts, D S

    2013-05-01

    This work presents a technique for measuring ultra-low power oscillator signals using an adaptive drift cancellation method. We demonstrate this technique through spectrum measurements of a sub-pW nano-magnet spin torque oscillator (STO). We first present a detailed noise analysis of the standard STO characterization apparatus to estimate the background noise level, then compare these results to the noise level of three measurement configurations. The first and second share the standard configuration but use different spectrum analyzers (SA), an older model and a state-of-the-art model, respectively. The third is the technique proposed in this work using the same old SA as for the first. Our results show that the first and second configurations suffer from a large drift that requires ~30 min to stabilize each time the SA changes the frequency band, even though the SA has been powered on for longer than 24 h. The third configuration introduced in this work, however, shows absolutely no drift as the SA changes frequency band, and nearly the same noise performance as with a state-of-the-art SA, thus providing a reliable method for measuring very low power signals for a wide variety of applications.

  6. Numerical bifurcation analysis of two coupled FitzHugh-Nagumo oscillators

    NASA Astrophysics Data System (ADS)

    Hoff, Anderson; dos Santos, Juliana V.; Manchein, Cesar; Albuquerque, Holokx A.

    2014-07-01

    The behavior of neurons can be modeled by the FitzHugh-Nagumo oscillator model, consisting of two nonlinear differential equations, which simulates the behavior of nerve impulse conduction through the neuronal membrane. In this work, we numerically study the dynamical behavior of two coupled FitzHugh-Nagumo oscillators. We consider unidirectional and bidirectional couplings, for which Lyapunov and isoperiodic diagrams were constructed calculating the Lyapunov exponents and the number of the local maxima of a variable in one period interval of the time-series, respectively. By numerical continuation method the bifurcation curves are also obtained for both couplings. The dynamics of the networks here investigated are presented in terms of the variation between the coupling strength of the oscillators and other parameters of the system. For the network of two oscillators unidirectionally coupled, the results show the existence of Arnold tongues, self-organized sequentially in a branch of a Stern-Brocot tree and by the bifurcation curves it became evident the connection between these Arnold tongues with other periodic structures in Lyapunov diagrams. That system also presents multistability shown in the planes of the basin of attractions.

  7. Imprints of superfluidity on magnetoelastic quasiperiodic oscillations of soft gamma-ray repeaters.

    PubMed

    Gabler, Michael; Cerdá-Durán, Pablo; Stergioulas, Nikolaos; Font, José A; Müller, Ewald

    2013-11-22

    Our numerical simulations show that axisymmetric, torsional, magnetoelastic oscillations of magnetars with a superfluid core can explain the whole range of observed quasiperiodic oscillations (QPOs) in the giant flares of soft gamma-ray repeaters. There exist constant phase QPOs at f is < or approximately equal to 150 Hz and resonantly excited high-frequency QPOs (f>500 Hz), in good agreement with observations. The range of magnetic field strengths required to match the observed QPO frequencies agrees with that from spin-down estimates. These results suggest that there is at least one superfluid species in magnetar cores.

  8. Stellar laboratories. II. New Zn iv and Zn v oscillator strengths and their validation in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-04-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191-B2B, 21 Zn iv lines were newly identified. Because of the lack of Zn iv data, transition probabilities of the isoelectronic Ge vi were adapted for a first, coarse determination of the photospheric Zn abundance. Aims: Reliable Zn iv and Zn v oscillator strengths are used to improve the Zn abundance determination and to identify more Zn lines in the spectra of G191-B2B and the DO-type white dwarf RE 0503-289. Methods: We performed new calculations of Zn iv and Zn v oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn iv - v spectrum exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: In the UV spectrum of G191-B2B, we identify 31 Zn iv and 16 Zn v lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn = -5.52 ± 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn iv / Zn v ionization equilibrium, which is a very sensitive Teff indicator, is well reproduced with the previously determined and log g = 7.60 ± 0.05. In the spectrum of RE 0503-289, we identified 128 Zn v lines for the first time and determined log Zn = -3.57 ± 0.2 (155 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn iv and Zn v line profiles in two white dwarf (G191-B2B and RE 0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to

  9. Pattern formation without diffraction matching in optical parametric oscillators with a metamaterial.

    PubMed

    Tassin, Philippe; Van der Sande, Guy; Veretennicoff, Irina; Kockaert, Pascal; Tlidi, Mustapha

    2009-05-25

    We consider a degenerate optical parametric oscillator containing a left-handed material. We show that the inclusion of a left-handed material layer allows for controlling the strength and sign of the diffraction coefficient at either the pump or the signal frequency. Subsequently, we demonstrate the existence of stable dissipative structures without diffraction matching, i.e., without the usual relationship between the diffraction coefficients of the signal and pump fields. Finally, we investigate the size scaling of these light structures with decreasing diffraction strength.

  10. Quenching oscillating behaviors in fractional coupled Stuart-Landau oscillators

    NASA Astrophysics Data System (ADS)

    Sun, Zhongkui; Xiao, Rui; Yang, Xiaoli; Xu, Wei

    2018-03-01

    Oscillation quenching has been widely studied during the past several decades in fields ranging from natural sciences to engineering, but investigations have so far been restricted to oscillators with an integer-order derivative. Here, we report the first study of amplitude death (AD) in fractional coupled Stuart-Landau oscillators with partial and/or complete conjugate couplings to explore oscillation quenching patterns and dynamics. It has been found that the fractional-order derivative impacts the AD state crucially. The area of the AD state increases along with the decrease of the fractional-order derivative. Furthermore, by introducing and adjusting a limiting feedback factor in coupling links, the AD state can be well tamed in fractional coupled oscillators. Hence, it provides one an effective approach to analyze and control the oscillating behaviors in fractional coupled oscillators.

  11. Revisiting an old concept: the coupled oscillator model for VCD. Part 2: implications of the generalised coupled oscillator mechanism for the VCD robustness concept.

    PubMed

    Nicu, Valentin Paul

    2016-08-03

    Using two illustrative examples it is shown that the generalised coupled oscillator (GCO) mechanism implies that the stability of the VCD sign computed for a given normal mode is not reflected by the magnitude of the ratio ζ between the rotational strength and dipole strength of the respective mode, i.e., the VCD robustness criterium proposed by Góbi and Magyarfalvi. The performed VCD GCO analysis brings further insight into the GCO mechanism and also into the VCD robustness concept. First, it shows that the GCO mechanism can be interpreted as a VCD resonance enhancement mechanism, i.e. very large VCD signals can be observed when the interacting molecular fragments are in favourable orientation. Second, it shows that the uncertainties observed in the computed VCD signs are associated to uncertainties in the relative orientation of the coupled oscillator fragments and/or to uncertainties in the predicted nuclear displacement vectors, i.e. not uncertainties in the computed magnetic dipole transition moments as was originally assumed. Since it is able to identify such situations easily, the VCD GCO analysis can be used as a VCD robustness analysis.

  12. Energy Levels and Spectral Lines of Li Atoms in White Dwarf Strength Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Zhao, L. B.

    2018-04-01

    A theoretical approach based on B-splines has been developed to calculate atomic structures and discrete spectra of Li atoms in a strong magnetic field typical of magnetic white dwarf stars. Energy levels are presented for 20 electronic states with the symmetries 20+, 20‑, 2(‑1)+, 2(‑1)‑, and 2(‑2)+. The magnetic field strengths involved range from 0 to 2350 MG. The wavelengths and oscillator strengths for the electric dipole transitions relevant to these magnetized atomic states are reported. The current results are compared to the limited theoretical data in the literature. A good agreement has been found for the lower energy levels, but a significant discrepancy is clearly visible for the higher energy levels. The existing discrepancies of the wavelengths and oscillator strengths are also discussed. Our investigation shows that the spectrum data of magnetized Li atoms previously published are obviously far from meeting requirements of analyzing discrete atomic spectra of magnetic white dwarfs with lithium atmospheres.

  13. Neurodynamic oscillators

    NASA Technical Reports Server (NTRS)

    Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz

    1995-01-01

    Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

  14. Bloch oscillations in organic and inorganic polymers

    NASA Astrophysics Data System (ADS)

    Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; de Almeida Fonseca, Antonio Luciano; e Silva, Geraldo Magela

    2017-04-01

    The transport of polarons above the mobility threshold in organic and inorganic polymers is theoretically investigated in the framework of a one-dimensional tight-binding model that includes lattice relaxation. The computational approach is based on parameters for which the model Hamiltonian suitably describes different polymer lattices in the presence of external electric fields. Our findings show that, above critical field strengths, a dissociated polaron moves through the polymer lattice as a free electron performing Bloch oscillations. These critical electric fields are considerably smaller for inorganic lattices in comparison to organic polymers. Interestingly, for inorganic lattices, the free electron propagates preserving charge and spin densities' localization which is a characteristic of a static polaron. Moreover, in the turning points of the spatial Bloch oscillations, transient polaron levels are formed inside the band gap, thus generating a fully characterized polaron structure. For the organic case, on the other hand, no polaron signature is observed: neither in the shape of the distortion—those polaron profile signatures are absent—nor in the energy levels—as no such polaron levels are formed during the simulation. These results solve controversial aspects concerning Bloch oscillations recently reported in the literature and may enlighten the understanding about the charge transport mechanism in polymers above their mobility edge.

  15. The role of barotropic oscillations within atmospheres of highly variable refractive index

    NASA Technical Reports Server (NTRS)

    Paegle, J.; Paegle, J. N.; Yan, H.

    1983-01-01

    Among the various energy transfer mechanisms that might be relevant for teleconnections between tropical and higher latitudes, Rossby wave propagation is certainly one of the most important. In view of this, it is of interest to understand how the propagation of Rossby waves might be affected by ambient flows which locally may be unable to sustain oscillations due to vorticity gradients. This concept is re-examined based on the observation that there are large areas over the Pacific where the upper tropospheric absolute vorticity and its horizontal gradient are small. These key areas for teleconnections might be suspected to be unfavorable to the local propagation of Rossby waves. Results of integrations of the barotropic vorticity equation on the sphere are presented to show the role that regions with small absolute vorticity gradient play in this problem. Implications regarding the maintenance of blocks and the influence of divergent effects are also addressed.

  16. Estimating the absolute wealth of households.

    PubMed

    Hruschka, Daniel J; Gerkey, Drew; Hadley, Craig

    2015-07-01

    To estimate the absolute wealth of households using data from demographic and health surveys. We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. The median absolute wealth estimates of 1,403,186 households were 2056 international dollars per capita (interquartile range: 723-6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R(2)  = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality.

  17. Singular unlocking transition in the Winfree model of coupled oscillators.

    PubMed

    Quinn, D Dane; Rand, Richard H; Strogatz, Steven H

    2007-03-01

    The Winfree model consists of a population of globally coupled phase oscillators with randomly distributed natural frequencies. As the coupling strength and the spread of natural frequencies are varied, the various stable states of the model can undergo bifurcations, nearly all of which have been characterized previously. The one exception is the unlocking transition, in which the frequency-locked state disappears abruptly as the spread of natural frequencies exceeds a critical width. Viewed as a function of the coupling strength, this critical width defines a bifurcation curve in parameter space. For the special case where the frequency distribution is uniform, earlier work had uncovered a puzzling singularity in this bifurcation curve. Here we seek to understand what causes the singularity. Using the Poincaré-Lindstedt method of perturbation theory, we analyze the locked state and its associated unlocking transition, first for an arbitrary distribution of natural frequencies, and then for discrete systems of N oscillators. We confirm that the bifurcation curve becomes singular for a continuum uniform distribution, yet find that it remains well behaved for any finite N , suggesting that the continuum limit is responsible for the singularity.

  18. Is an absolute level of cortical beta suppression required for proper movement? Magnetoencephalographic evidence from healthy aging.

    PubMed

    Heinrichs-Graham, Elizabeth; Wilson, Tony W

    2016-07-01

    Previous research has connected a specific pattern of beta oscillatory activity to proper motor execution, but no study to date has directly examined how resting beta levels affect motor-related beta oscillatory activity in the motor cortex. Understanding this relationship is imperative to determining the basic mechanisms of motor control, as well as the impact of pathological beta oscillations on movement execution. In the current study, we used magnetoencephalography (MEG) and a complex movement paradigm to quantify resting beta activity and movement-related beta oscillations in the context of healthy aging. We chose healthy aging as a model because preliminary evidence suggests that beta activity is elevated in older adults, and thus by examining older and younger adults we were able to naturally vary resting beta levels. To this end, healthy younger and older participants were recorded during motor performance and at rest. Using beamforming, we imaged the peri-movement beta event-related desynchronization (ERD) and extracted virtual sensors from the peak voxels, which enabled absolute and relative beta power to be assessed. Interestingly, absolute beta power during the pre-movement baseline was much stronger in older relative to younger adults, and older adults also exhibited proportionally large beta desynchronization (ERD) responses during motor planning and execution compared to younger adults. Crucially, we found a significant relationship between spontaneous (resting) beta power and beta ERD magnitude in both primary motor cortices, above and beyond the effects of age. A similar link was found between beta ERD magnitude and movement duration. These findings suggest a direct linkage between beta reduction during movement and spontaneous activity in the motor cortex, such that as spontaneous beta power increases, a greater reduction in beta activity is required to execute movement. We propose that, on an individual level, the primary motor cortices have an

  19. Improved automatic steam distillation combined with oscillation-type densimetry for determining alcoholic strength in spirits and liqueurs.

    PubMed

    Lachenmeier, Dirk W; Plato, Leander; Suessmann, Manuela; Di Carmine, Matthew; Krueger, Bjoern; Kukuck, Armin; Kranz, Markus

    2015-01-01

    The determination of the alcoholic strength in spirits and liqueurs is required to control the labelling of alcoholic beverages. The reference methodology prescribes a distillation step followed by densimetric measurement. The classic distillation using a Vigreux rectifying column and a West condenser is time consuming and error-prone, especially for liqueurs that may have problems with entrainment and charring. For this reason, this methodology suggests the use of an automated steam distillation device as alternative. The novel instrument comprises an increased steam power, a redesigned geometry of the condenser and a larger cooling coil with controllable flow, compared to previously available devices. Method optimization applying D-optimal and central composite designs showed significant influence of sample volume, distillation time and coolant flow, while other investigated parameters such as steam power, receiver volume, or the use of pipettes or flasks for sample measurement did not significantly influence the results. The method validation was conducted using the following settings: steam power 70 %, sample volume 25 mL transferred using pipettes, receiver volume 50 mL, coolant flow 7 L/min, and distillation time as long as possible just below the calibration mark. For four different liqueurs covering the typical range of these products between 15 and 35 % vol, the method showed an adequate precision, with relative standard deviations below 0.4 % (intraday) and below 0.6 % (interday). The absolute standard deviations were between 0.06 % vol and 0.08 % vol (intraday) and between 0.07 % vol and 0.10 % vol (interday). The improved automatic steam distillation devices offer an excellent alternative for sample cleanup of volatiles from complex matrices. A major advantage are the low costs for consumables per analysis (only distilled water is needed). For alcoholic strength determination, the method has become more rugged than before, and there are only

  20. One-dimensional polaritons with size-tunable and enhanced coupling strengths in semiconductor nanowires.

    PubMed

    van Vugt, Lambert K; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh

    2011-06-21

    Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk.

  1. One-dimensional polaritons with size-tunable and enhanced coupling strengths in semiconductor nanowires

    PubMed Central

    van Vugt, Lambert K.; Piccione, Brian; Cho, Chang-Hee; Nukala, Pavan; Agarwal, Ritesh

    2011-01-01

    Strong coupling of light with excitons in direct bandgap semiconductors leads to the formation of composite photonic-electronic quasi-particles (polaritons), in which energy oscillates coherently between the photonic and excitonic states with the vacuum Rabi frequency. The light-matter coherence is maintained until the oscillator dephases or the photon escapes. Exciton-polariton formation has enabled the observation of Bose-Einstein condensation in the solid-state, low-threshold polariton lasing and is also useful for terahertz and slow-light applications. However, maintaining coherence for higher carrier concentration and temperature applications still requires increased coupling strengths. Here, we report on size-tunable, exceptionally high exciton-polariton coupling strengths characterized by a vacuum Rabi splitting of up to 200 meV as well as a reduction in group velocity, in surface-passivated, self-assembled semiconductor nanowire cavities. These experiments represent systematic investigations on light-matter coupling in one-dimensional optical nanocavities, demonstrating the ability to engineer light-matter coupling strengths at the nanoscale, even in non-quantum-confined systems, to values much higher than in bulk. PMID:21628582

  2. Using oceanic-atmospheric oscillations for long lead time streamflow forecasting

    NASA Astrophysics Data System (ADS)

    Kalra, Ajay; Ahmad, Sajjad

    2009-03-01

    We present a data-driven model, Support Vector Machine (SVM), for long lead time streamflow forecasting using oceanic-atmospheric oscillations. The SVM is based on statistical learning theory that uses a hypothesis space of linear functions based on Kernel approach and has been used to predict a quantity forward in time on the basis of training from past data. The strength of SVM lies in minimizing the empirical classification error and maximizing the geometric margin by solving inverse problem. The SVM model is applied to three gages, i.e., Cisco, Green River, and Lees Ferry in the Upper Colorado River Basin in the western United States. Annual oceanic-atmospheric indices, comprising Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Nino-Southern Oscillations (ENSO) for a period of 1906-2001 are used to generate annual streamflow volumes with 3 years lead time. The SVM model is trained with 86 years of data (1906-1991) and tested with 10 years of data (1992-2001). On the basis of correlation coefficient, root means square error, and Nash Sutcliffe Efficiency Coefficient the model shows satisfactory results, and the predictions are in good agreement with measured streamflow volumes. Sensitivity analysis, performed to evaluate the effect of individual and coupled oscillations, reveals a strong signal for ENSO and NAO indices as compared to PDO and AMO indices for the long lead time streamflow forecast. Streamflow predictions from the SVM model are found to be better when compared with the predictions obtained from feedforward back propagation artificial neural network model and linear regression.

  3. Lifetimes and oscillator strengths for the 5s5p6s, 5s5p5d and 5p3 levels in single-ionized tin

    NASA Astrophysics Data System (ADS)

    Colón, C.; Alonso-Medina, A.

    2004-08-01

    Radiative oscillator strengths for 103 lines arising from 5s5p6s, 5s5p5d and 5p3 configurations of Sn II and lifetimes corresponding to several levels of these configurations have been calculated. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree-Fock (HFR) calculations. We use the standard method of least square fitting of experimental energy levels for the IC calculations by means of computer codes from Cowan. Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/1109

  4. Chimera states in two-dimensional networks of locally coupled oscillators

    NASA Astrophysics Data System (ADS)

    Kundu, Srilena; Majhi, Soumen; Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2018-02-01

    Chimera state is defined as a mixed type of collective state in which synchronized and desynchronized subpopulations of a network of coupled oscillators coexist and the appearance of such anomalous behavior has strong connection to diverse neuronal developments. Most of the previous studies on chimera states are not extensively done in two-dimensional ensembles of coupled oscillators by taking neuronal systems with nonlinear coupling function into account while such ensembles of oscillators are more realistic from a neurobiological point of view. In this paper, we report the emergence and existence of chimera states by considering locally coupled two-dimensional networks of identical oscillators where each node is interacting through nonlinear coupling function. This is in contrast with the existence of chimera states in two-dimensional nonlocally coupled oscillators with rectangular kernel in the coupling function. We find that the presence of nonlinearity in the coupling function plays a key role to produce chimera states in two-dimensional locally coupled oscillators. We analytically verify explicitly in the case of a network of coupled Stuart-Landau oscillators in two dimensions that the obtained results using Ott-Antonsen approach and our analytical finding very well matches with the numerical results. Next, we consider another type of important nonlinear coupling function which exists in neuronal systems, namely chemical synaptic function, through which the nearest-neighbor (locally coupled) neurons interact with each other. It is shown that such synaptic interacting function promotes the emergence of chimera states in two-dimensional lattices of locally coupled neuronal oscillators. In numerical simulations, we consider two paradigmatic neuronal oscillators, namely Hindmarsh-Rose neuron model and Rulkov map for each node which exhibit bursting dynamics. By associating various spatiotemporal behaviors and snapshots at particular times, we study the chimera

  5. Chimera states in two-dimensional networks of locally coupled oscillators.

    PubMed

    Kundu, Srilena; Majhi, Soumen; Bera, Bidesh K; Ghosh, Dibakar; Lakshmanan, M

    2018-02-01

    Chimera state is defined as a mixed type of collective state in which synchronized and desynchronized subpopulations of a network of coupled oscillators coexist and the appearance of such anomalous behavior has strong connection to diverse neuronal developments. Most of the previous studies on chimera states are not extensively done in two-dimensional ensembles of coupled oscillators by taking neuronal systems with nonlinear coupling function into account while such ensembles of oscillators are more realistic from a neurobiological point of view. In this paper, we report the emergence and existence of chimera states by considering locally coupled two-dimensional networks of identical oscillators where each node is interacting through nonlinear coupling function. This is in contrast with the existence of chimera states in two-dimensional nonlocally coupled oscillators with rectangular kernel in the coupling function. We find that the presence of nonlinearity in the coupling function plays a key role to produce chimera states in two-dimensional locally coupled oscillators. We analytically verify explicitly in the case of a network of coupled Stuart-Landau oscillators in two dimensions that the obtained results using Ott-Antonsen approach and our analytical finding very well matches with the numerical results. Next, we consider another type of important nonlinear coupling function which exists in neuronal systems, namely chemical synaptic function, through which the nearest-neighbor (locally coupled) neurons interact with each other. It is shown that such synaptic interacting function promotes the emergence of chimera states in two-dimensional lattices of locally coupled neuronal oscillators. In numerical simulations, we consider two paradigmatic neuronal oscillators, namely Hindmarsh-Rose neuron model and Rulkov map for each node which exhibit bursting dynamics. By associating various spatiotemporal behaviors and snapshots at particular times, we study the chimera

  6. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  7. Time delay induced different synchronization patterns in repulsively coupled chaotic oscillators

    NASA Astrophysics Data System (ADS)

    Yao, Chenggui; Yi, Ming; Shuai, Jianwei

    2013-09-01

    Time delayed coupling plays a crucial role in determining the system's dynamics. We here report that the time delay induces transition from the asynchronous state to the complete synchronization (CS) state in the repulsively coupled chaotic oscillators. In particular, by changing the coupling strength or time delay, various types of synchronous patterns, including CS, antiphase CS, antiphase synchronization (ANS), and phase synchronization, can be generated. In the transition regions between different synchronous patterns, bistable synchronous oscillators can be observed. Furthermore, we show that the time-delay-induced phase flip bifurcation is of key importance for the emergence of CS. All these findings may light on our understanding of neuronal synchronization and information processing in the brain.

  8. Stellar laboratories. III. New Ba v, Ba vi, and Ba vii oscillator strengths and the barium abundance in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2014-06-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: Reliable Ba v-vii oscillator strengths are used to identify Ba lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ba abundances. Methods: We newly calculated Ba v-vii oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of Ba lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: For the first time, we identified highly ionized Ba in the spectra of hot white dwarfs. We detected Ba vi and Ba vii lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The Ba vi/Ba vii ionization equilibrium is well reproduced with the previously determined effective temperature of 70 000 K and surface gravity of log g = 7.5. The Ba abundance is 3.5 ± 0.5 × 10-4 (mass fraction, about 23 000 times the solar value). In the FUSE spectrum of G191-B2B, we identified the strongest Ba vii line (at 993.41 Å) only, and determined a Ba abundance of 4.0 ± 0.5 × 10-6 (about 265 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Ba vi-vii line profiles in two white dwarfs' (G191-B2B and RE 0503-289) far-ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed to determine the photospheric Ba abundance of these two stars precisely. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for

  9. Hamstring and Quadriceps Isokinetic Strength Deficits Are Weak Risk Factors for Hamstring Strain Injuries: A 4-Year Cohort Study.

    PubMed

    van Dyk, Nicol; Bahr, Roald; Whiteley, Rodney; Tol, Johannes L; Kumar, Bhavesh D; Hamilton, Bruce; Farooq, Abdulaziz; Witvrouw, Erik

    2016-07-01

    A hamstring strain injury (HSI) has become the most common noncontact injury in soccer. Isokinetic muscle strength deficits are considered a risk factor for HSIs. However, underpowered studies with small sample sizes unable to determine small associations have led to inconclusive results regarding the role of isokinetic strength and strength testing in HSIs. To examine whether differences in isokinetic strength measures of knee flexion and extension represent risk factors for hamstring injuries in a large cohort of professional soccer players in an adequately powered study design. Cohort study; Level of evidence, 2. A total of 614 professional soccer players from 14 teams underwent isokinetic strength testing during preseason screening. Testing consisted of concentric knee flexion and extension at 60 deg/s and 300 deg/s and eccentric knee extension at 60 deg/s. A clustered multiple logistic regression analysis was used to identify variables associated with the risk of HSIs. Receiver operating characteristic (ROC) curves were calculated to determine sensitivity and specificity. Of the 614 players, 190 suffered an HSI during the 4 seasons. Quadriceps concentric strength at 60 deg/s (odds ratio [OR], 1.41; 95% CI, 1.03-1.92; P = .03) and hamstring eccentric strength at 60 deg/s (OR, 1.37; 95% CI, 1.01-1.85; P = .04) adjusted for bodyweight were independently associated with the risk of injuries. The absolute differences between the injured and uninjured players were 6.9 N·m and 9.1 N·m, with small effect sizes (d < 0.2). The ROC analyses showed an area under the curve of 0.54 and 0.56 for quadriceps concentric strength and hamstring eccentric strength, respectively, indicating a failed combined sensitivity and specificity of the 2 strength variables identified in the logistic regression models. This study identified small absolute strength differences and a wide overlap of the absolute strength measurements at the group level. The small associations between lower

  10. Mean-field behavior in coupled oscillators with attractive and repulsive interactions.

    PubMed

    Hong, Hyunsuk; Strogatz, Steven H

    2012-05-01

    We consider a variant of the Kuramoto model of coupled oscillators in which both attractive and repulsive pairwise interactions are allowed. The sign of the coupling is assumed to be a characteristic of a given oscillator. Specifically, some oscillators repel all the others, thus favoring an antiphase relationship with them. Other oscillators attract all the others, thus favoring an in-phase relationship. The Ott-Antonsen ansatz is used to derive the exact low-dimensional dynamics governing the system's long-term macroscopic behavior. The resulting analytical predictions agree with simulations of the full system. We explore the effects of changing various parameters, such as the width of the distribution of natural frequencies and the relative strengths and proportions of the positive and negative interactions. For the particular model studied here we find, unexpectedly, that the mixed interactions produce no new effects. The system exhibits conventional mean-field behavior and displays a second-order phase transition like that found in the original Kuramoto model. In contrast to our recent study of a different model with mixed interactions [Phys. Rev. Lett. 106, 054102 (2011)], the π state and traveling-wave state do not appear for the coupling type considered here.

  11. Resurgence of oscillation in coupled oscillators under delayed cyclic interaction

    NASA Astrophysics Data System (ADS)

    Bera, Bidesh K.; Majhi, Soumen; Ghosh, Dibakar

    2017-07-01

    This paper investigates the emergence of amplitude death and revival of oscillations from the suppression states in a system of coupled dynamical units interacting through delayed cyclic mode. In order to resurrect the oscillation from amplitude death state, we introduce asymmetry and feedback parameter in the cyclic coupling forms as a result of which the death region shrinks due to higher asymmetry and lower feedback parameter values for coupled oscillatory systems. Some analytical conditions are derived for amplitude death and revival of oscillations in two coupled limit cycle oscillators and corresponding numerical simulations confirm the obtained theoretical results. We also report that the death state and revival of oscillations from quenched state are possible in the network of identical coupled oscillators. The proposed mechanism has also been examined using chaotic Lorenz oscillator.

  12. 20 CFR 404.1205 - Absolute coverage groups.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Absolute coverage groups. 404.1205 Section... Covered § 404.1205 Absolute coverage groups. (a) General. An absolute coverage group is a permanent... are not under a retirement system. An absolute coverage group may include positions which were...

  13. Precise dating of Dansgaard-Oeschger climate oscillations in western Europe from stalagmite data.

    PubMed

    Genty, D; Blamart, D; Ouahdi, R; Gilmour, M; Baker, A; Jouzel, J; Van-Exter, Sandra

    2003-02-20

    The signature of Dansgaard-Oeschger events--millennial-scale abrupt climate oscillations during the last glacial period--is well established in ice cores and marine records. But the effects of such events in continental settings are not as clear, and their absolute chronology is uncertain beyond the limit of (14)C dating and annual layer counting for marine records and ice cores, respectively. Here we present carbon and oxygen isotope records from a stalagmite collected in southwest France which have been precisely dated using 234U/230Th ratios. We find rapid climate oscillations coincident with the established Dansgaard-Oeschger events between 83,000 and 32,000 years ago in both isotope records. The oxygen isotope signature is similar to a record from Soreq cave, Israel, and deep-sea records, indicating the large spatial scale of the climate oscillations. The signal in the carbon isotopes gives evidence of drastic and rapid vegetation changes in western Europe, an important site in human cultural evolution. We also find evidence for a long phase of extremely cold climate in southwest France between 61.2 +/- 0.6 and 67.4 +/- 0.9 kyr ago.

  14. The Edge of Stability: Response Times and Delta Oscillations in Balanced Networks

    PubMed Central

    Gillary, Grant; Niebur, Ernst

    2016-01-01

    The standard architecture of neocortex is a network with excitation and inhibition in closely maintained balance. These networks respond fast and with high precision to their inputs and they allow selective amplification of patterned signals. The stability of such networks is known to depend on balancing the strengths of positive and negative feedback. We here show that a second condition is required for stability which depends on the relative strengths and time courses of fast (AMPA) and slow (NMDA) currents in the excitatory projections. This condition also determines the response time of the network. We show that networks which respond quickly to an input are necessarily close to an oscillatory instability which resonates in the delta range. This instability explains the existence of neocortical delta oscillations and the emergence of absence epilepsy. Although cortical delta oscillations are a network-level phenomenon, we show that in non-pathological networks, individual neurons receive sufficient information to keep the network in the fast-response regime without sliding into the instability. PMID:27689361

  15. The impact of obesity on skeletal muscle strength and structure through adolescence to old age.

    PubMed

    Tomlinson, D J; Erskine, R M; Morse, C I; Winwood, K; Onambélé-Pearson, Gladys

    2016-06-01

    Obesity is associated with functional limitations in muscle performance and increased likelihood of developing a functional disability such as mobility, strength, postural and dynamic balance limitations. The consensus is that obese individuals, regardless of age, have a greater absolute maximum muscle strength compared to non-obese persons, suggesting that increased adiposity acts as a chronic overload stimulus on the antigravity muscles (e.g., quadriceps and calf), thus increasing muscle size and strength. However, when maximum muscular strength is normalised to body mass, obese individuals appear weaker. This relative weakness may be caused by reduced mobility, neural adaptations and changes in muscle morphology. Discrepancies in the literature remain for maximal strength normalised to muscle mass (muscle quality) and can potentially be explained through accounting for the measurement protocol contributing to muscle strength capacity that need to be explored in more depth such as antagonist muscle co-activation, muscle architecture, a criterion valid measurement of muscle size and an accurate measurement of physical activity levels. Current evidence demonstrating the effect of obesity on muscle quality is limited. These factors not being recorded in some of the existing literature suggest a potential underestimation of muscle force either in terms of absolute force production or relative to muscle mass; thus the true effect of obesity upon skeletal muscle size, structure and function, including any interactions with ageing effects, remains to be elucidated.

  16. Spontaneous switching among multiple spatio-temporal patterns in three-oscillator systems constructed with oscillatory cells of true slime mold

    NASA Astrophysics Data System (ADS)

    Takamatsu, Atsuko

    2006-11-01

    Three-oscillator systems with plasmodia of true slime mold, Physarum polycephalum, which is an oscillatory amoeba-like unicellular organism, were experimentally constructed and their spatio-temporal patterns were investigated. Three typical spatio-temporal patterns were found: rotation ( R), partial in-phase ( PI), and partial anti-phase with double frequency ( PA). In pattern R, phase differences between adjacent oscillators were almost 120 ∘. In pattern PI, two oscillators were in-phase and the third oscillator showed anti-phase against the two oscillators. In pattern PA, two oscillators showed anti-phase and the third oscillator showed frequency doubling oscillation with small amplitude. Actually each pattern is not perfectly stable but quasi-stable. Interestingly, the system shows spontaneous switching among the multiple quasi-stable patterns. Statistical analyses revealed a characteristic in the residence time of each pattern: the histograms seem to have Gamma-like distribution form but with a sharp peak and a tail on the side of long period. That suggests the attractor of this system has complex structure composed of at least three types of sub-attractors: a “Gamma attractor”-involved with several Poisson processes, a “deterministic attractor”-the residence time is deterministic, and a “stable attractor”-each pattern is stable. When the coupling strength was small, only the Gamma attractor was observed and switching behavior among patterns R, PI, and PA almost always via an asynchronous pattern named O. A conjecture is as follows: Internal/external noise exposes each pattern of R, PI, and PA coexisting around bifurcation points: That is observed as the Gamma attractor. As coupling strength increases, the deterministic attractor appears then followed by the stable attractor, always accompanied with the Gamma attractor. Switching behavior could be caused by regular existence of the Gamma attractor.

  17. Isometric and isokinetic muscle strength in the upper extremity can be reliably measured in persons with chronic stroke.

    PubMed

    Ekstrand, Elisabeth; Lexell, Jan; Brogårdh, Christina

    2015-09-01

    To evaluate the test-retest reliability of isometric and isokinetic muscle strength measurements in the upper extremity after stroke. A test-retest design. Forty-five persons with mild to moderate paresis in the upper extremity > 6 months post-stroke. Isometric arm strength (shoulder abduction, elbow flexion), isokinetic arm strength (elbow extension/flexion) and isometric grip strength were measured with electronic dynamometers. Reliability was evaluated with intra-class correlation coefficients (ICC), changes in the mean, standard error of measurements (SEM) and smallest real differences (SRD). Reliability was high (ICCs: 0.92-0.97). The absolute and relative (%) SEM ranged from 2.7 Nm (5.6%) to 3.0 Nm (9.4%) for isometric arm strength, 2.6 Nm (7.4%) to 2.9 Nm (12.6%) for isokinetic arm strength, and 22.3 N (7.6%) to 26.4 N (9.2%) for grip strength. The absolute and relative (%) SRD ranged from 7.5 Nm (15.5%) to 8.4 Nm (26.1%) for isometric arm strength, 7.1 Nm (20.6%) to 8.0 Nm (34.8%) for isokinetic arm strength, and 61.8 N (21.0%) to 73.3 N (25.6%) for grip strength. Muscle strength in the upper extremity can be reliably measured in persons with chronic stroke. Isometric measurements yield smaller measurement errors than isokinetic measurements and might be preferred, but the choice depends on the research question.

  18. Chemical oscillator as a generalized Rayleigh oscillator.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2013-10-28

    We derive the conditions under which a set of arbitrary two dimensional autonomous kinetic equations can be reduced to the form of a generalized Rayleigh oscillator which admits of limit cycle solution. This is based on a linear transformation of field variables which can be found by inspection of the kinetic equations. We illustrate the scheme with the help of several chemical and bio-chemical oscillator models to show how they can be cast as a generalized Rayleigh oscillator.

  19. Measurement of the absolute v μ-CCQE cross section at the SciBooNE experiment

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

    Aunion, Jose Luis Alcaraz

    2010-07-01

    This thesis presents the measurement of the charged current quasi-elastic (CCQE) neutrino-nucleon cross section at neutrino energies around 1 GeV. This measurement has two main physical motivations. On one hand, the neutrino-nucleon interactions at few GeV is a region where existing old data are sparse and with low statistics. The current measurement populates low energy regions with higher statistics and precision than previous experiments. On the other hand, the CCQE interaction is the most useful interaction in neutrino oscillation experiments. The CCQE channel is used to measure the initial and final neutrino fluxes in order to determine the neutrino fractionmore » that disappeared. The neutrino oscillation experiments work at low neutrino energies, so precise measurement of CCQE interactions are essential for flux measurements. The main goal of this thesis is to measure the CCQE absolute neutrino cross section from the SciBooNE data. The SciBar Booster Neutrino Experiment (SciBooNE) is a neutrino and anti-neutrino scattering off experiment. The neutrino energy spectrum works at energies around 1 GeV. SciBooNE was running from June 8th 2007 to August 18th 2008. In that period, the experiment collected a total of 2.65 x 10 20 protons on target (POT). This thesis has used full data collection in neutrino mode 0.99 x 10 20 POT. A CCQE selection cut has been performed, achieving around 70% pure CCQE sample. A fit method has been exclusively developed to determine the absolute CCQE cross section, presenting results in a neutrino energy range from 0.2 to 2 GeV. The results are compatible with the NEUT predictions. The SciBooNE measurement has been compared with both Carbon (MiniBoonE) and deuterium (ANL and BNL) target experiments, showing a good agreement in both cases.« less

  20. Nature's Autonomous Oscillators

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  1. The Role of Perceived Speed in Vection: Does Perceived Speed Modulate the Jitter and Oscillation Advantages?

    PubMed Central

    Apthorp, Deborah; Palmisano, Stephen

    2014-01-01

    Illusory self-motion (‘vection’) in depth is strongly enhanced when horizontal/vertical simulated viewpoint oscillation is added to optic flow inducing displays; a similar effect is found for simulated viewpoint jitter. The underlying cause of these oscillation and jitter advantages for vection is still unknown. Here we investigate the possibility that perceived speed of motion in depth (MID) plays a role. First, in a 2AFC procedure, we obtained MID speed PSEs for briefly presented (vertically oscillating and smooth) radial flow displays. Then we examined the strength, duration and onset latency of vection induced by oscillating and smooth radial flow displays matched either for simulated or perceived MID speed. The oscillation advantage was eliminated when displays were matched for perceived MID speed. However, when we tested the jitter advantage in the same manner, jittering displays were found to produce greater vection in depth than speed-matched controls. In summary, jitter and oscillation advantages were the same across experiments, but slower MID speed was required to match jittering than oscillating stimuli. Thus, to the extent that vection is driven by perceived speed of MID, this effect is greater for oscillating than for jittering stimuli, which suggests that the two effects may arise from separate mechanisms. PMID:24651861

  2. High-resolution oscillator strength measurements for the A(v') - X(0) bands of carbon monoxide with 11 less than or equal to v' less than or equal to 14

    NASA Technical Reports Server (NTRS)

    Smith, Peter L.; Stark, G.; Yoshino, K.; Ito, K.

    1994-01-01

    Band oscillator strengths (f-values) for four bands of the Fourth Positive system (A (1)Pi - Chi(sup 1) Sigma(+)) of CO have been determined from high-resolution (lambda/Delta lambda approximately equal to 150,000) absorption spectra. The bands, (14, 0) through (11, 0), are at wavelengths between 121 and 127 nm. Our f-values for the (11, 0) and (12, 0) bands support those of Chan, Cooper, & Brion (1993), which have been shown to be consistent with observations of CO in the clouds in the line of sight to zeta Oph. Our f-values for the (13, 0) and (14, 0) bands are the first directly measured values for these bands.

  3. CNTF 1357 G -> A polymorphism and the muscle strength response to resistance training.

    PubMed

    Walsh, Sean; Kelsey, Bethany K; Angelopoulos, Theodore J; Clarkson, Priscilla M; Gordon, Paul M; Moyna, Niall M; Visich, Paul S; Zoeller, Robert F; Seip, Richard L; Bilbie, Steve; Thompson, Paul D; Hoffman, Eric P; Price, Thomas B; Devaney, Joseph M; Pescatello, Linda S

    2009-10-01

    The present study examined associations between the ciliary neurotrophic factor (CNTF) 1357 G --> A polymorphism and the muscle strength response to a unilateral, upper arm resistance-training (RT) program among healthy, young adults. Subjects were 754 Caucasian men (40%) and women (60%) who were genotyped and performed a training program of the nondominant (trained) arm with the dominant (untrained) arm as a comparison. Peak elbow flexor strength was measured with one repetition maximum, isometric strength with maximum voluntary contraction, and bicep cross-sectional area with MRI in the trained and untrained arms before and after training. Women with the CNTF GG genotype gained more absolute isometric strength, as measured by MVC (6.5 +/- 0.3 vs. 5.2 +/- 0.5 kg), than carriers of the CNTF A1357 allele in the trained arm pre- to posttraining (P < 0.05). No significant associations were seen in men. Women with the CNTF GG genotype gained more absolute dynamic (1.0 +/- 0.1 vs. 0.6 +/- 0.1 kg) and allometric (0.022 +/- 0.0 vs. 0.015 +/- 0.0 kg/kg(-0.67)) strength, as measured by 1 RM, than carriers of the CNTF A1357 allele in the untrained arm pre- to posttraining (P < 0.05). No significant associations were seen in men. No significant associations, as measured by cross-sectional area, were seen in men or women. The CNTF 1357 G --> A polymorphism explains only a small portion of the variability in the muscle strength response to training in women.

  4. Spindle Oscillations in Sleep Disorders: A Systematic Review

    PubMed Central

    Weiner, Oren M.

    2016-01-01

    Measurement of sleep microarchitecture and neural oscillations is an increasingly popular technique for quantifying EEG sleep activity. Many studies have examined sleep spindle oscillations in sleep-disordered adults; however reviews of this literature are scarce. As such, our overarching aim was to critically review experimental studies examining sleep spindle activity between adults with and without different sleep disorders. Articles were obtained using a systematic methodology with a priori criteria. Thirty-seven studies meeting final inclusion criteria were reviewed, with studies grouped across three categories: insomnia, hypersomnias, and sleep-related movement disorders (including parasomnias). Studies of patients with insomnia and sleep-disordered breathing were more abundant relative to other diagnoses. All studies were cross-sectional. Studies were largely inconsistent regarding spindle activity differences between clinical and nonclinical groups, with some reporting greater or less activity, while many others reported no group differences. Stark inconsistencies in sample characteristics (e.g., age range and diagnostic criteria) and methods of analysis (e.g., spindle bandwidth selection, visual detection versus digital filtering, absolute versus relative spectral power, and NREM2 versus NREM3) suggest a need for greater use of event-based detection methods and increased research standardization. Hypotheses regarding the clinical and empirical implications of these findings, and suggestions for potential future studies, are also discussed. PMID:27034850

  5. Vertical Oscillation of a Coronal Cavity Triggered by an EUV Wave

    NASA Astrophysics Data System (ADS)

    Zhang, Q. M.; Ji, H. S.

    2018-06-01

    In this paper, we report our multiwavelength observations of the vertical oscillation of a coronal cavity on 2011 March 16. The elliptical cavity with an underlying horn-like quiescent prominence was observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. The width and height of the cavity are 150″ and 240″, and the centroid of cavity is 128″ above the solar surface. At ∼17:50 UT, a C3.8 two-ribbon flare took place in active region 11169 close to the solar western limb. Meanwhile, a partial halo coronal mass ejection erupted and propagated at a linear speed of ∼682 km s‑1. Associated with the eruption, a coronal extreme-ultraviolet (EUV) wave was generated and propagated in the northeast direction at a speed of ∼120 km s‑1. Once the EUV wave arrived at the cavity from the top, it pushed the large-scale overlying magnetic field lines downward before bouncing back. At the same time, the cavity started to oscillate coherently in the vertical direction and lasted for ∼2 cycles before disappearing. The amplitude, period, and damping time are 2.4–3.5 Mm, 29–37 minutes, and 26–78 minutes, respectively. The vertical oscillation of the cavity is explained by a global standing MHD wave of fast kink mode. To estimate the magnetic field strength of the cavity, we use two independent methods of prominence seismology. It is found that the magnetic field strength is only a few Gauss and less than 10 G.

  6. Humidification during high-frequency oscillation ventilation is affected by ventilator circuit and ventilatory setting.

    PubMed

    Chikata, Yusuke; Imanaka, Hideaki; Onishi, Yoshiaki; Ueta, Masahiko; Nishimura, Masaji

    2009-08-01

    High-frequency oscillation ventilation (HFOV) is an accepted ventilatory mode for acute respiratory failure in neonates. As conventional mechanical ventilation, inspiratory gas humidification is essential. However, humidification during HFOV has not been clarified. In this bench study, we evaluated humidification during HFOV in the open circumstance of ICU. Our hypothesis is that humidification during HFOV is affected by circuit design and ventilatory settings. We connected a ventilator with HFOV mode to a neonatal lung model that was placed in an infant incubator set at 37 degrees C. We set a heated humidifier (Fisher & Paykel) to obtain 37 degrees C at the chamber outlet and 40 degrees C at the distal temperature probe. We measured absolute humidity and temperature at the Y-piece using a rapid-response hygrometer. We evaluated two types of ventilator circuit: a circuit with inner heating wire and another with embedded heating element. In addition, we evaluated three lengths of the inspiratory limb, three stroke volumes, three frequencies, and three mean airway pressures. The circuit with embedded heating element provided significantly higher absolute humidity and temperature than one with inner heating wire. As an extended tube lacking a heating wire was shorter, absolute humidity and temperature became higher. In the circuit with inner heating wire, absolute humidity and temperature increased as stroke volume increased. Humidification during HFOV is affected by circuit design and ventilatory settings.

  7. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  8. The Onset of the Madden-Julian Oscillation Within an Aquaplanet Model

    NASA Technical Reports Server (NTRS)

    Colon, Edward; Lindesay, James; Suarez, Max

    1997-01-01

    A series of numerical experiments using a two-level atmospheric general circulation model (AGCM) were performed for the purpose of investigating the coupling between sea surface temperature (SST) profile and the onset of the Madden-Julian Oscillation (MJO). The AGCM was modified to run as an aquaplane with all seasonal forcing removed. SST distributions based on the New Global Sea-Ice and Sea Surface Temperature (GISST) Data Set for 1903-1994 were generated then modified to vary the north-south gradient and tropical temperatures. It was found that the MJO signal did not depend on the SST temperature gradients but rather on the absolute temperature of the equatorial region, EOF analysis revealed that the SST distribution which generated the strongest MJO signal produced a periodic fluctuation in velocity potential at the 250 millibar level with a phase speed of 15 m/s, and a periodicity of 30 days which falls within the shortest limit of observed oscillations. This distribution also possessed the coolest equatorial SSTs which suggests that increased stability in the atmosphere favors the occurrence of organized MJO propagation.

  9. Finding brain oscillations with power dependencies in neuroimaging data.

    PubMed

    Dähne, Sven; Nikulin, Vadim V; Ramírez, David; Schreier, Peter J; Müller, Klaus-Robert; Haufe, Stefan

    2014-08-01

    Phase synchronization among neuronal oscillations within the same frequency band has been hypothesized to be a major mechanism for communication between different brain areas. On the other hand, cross-frequency communications are more flexible allowing interactions between oscillations with different frequencies. Among such cross-frequency interactions amplitude-to-amplitude interactions are of a special interest as they show how the strength of spatial synchronization in different neuronal populations relates to each other during a given task. While, previously, amplitude-to-amplitude correlations were studied primarily on the sensor level, we present a source separation approach using spatial filters which maximize the correlation between the envelopes of brain oscillations recorded with electro-/magnetoencephalography (EEG/MEG) or intracranial multichannel recordings. Our approach, which is called canonical source power correlation analysis (cSPoC), is thereby capable of extracting genuine brain oscillations solely based on their assumed coupling behavior even when the signal-to-noise ratio of the signals is low. In addition to using cSPoC for the analysis of cross-frequency interactions in the same subject, we show that it can also be utilized for studying amplitude dynamics of neuronal oscillations across subjects. We assess the performance of cSPoC in simulations as well as in three distinctively different analysis scenarios of real EEG data, each involving several subjects. In the simulations, cSPoC outperforms unsupervised state-of-the-art approaches. In the analysis of real EEG recordings, we demonstrate excellent unsupervised discovery of meaningful power-to-power couplings, within as well as across subjects and frequency bands. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. QUASI-BIENNIAL OSCILLATIONS IN THE SOLAR TACHOCLINE CAUSED BY MAGNETIC ROSSBY WAVE INSTABILITIES

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

    Zaqarashvili, Teimuraz V.; Carbonell, Marc; Oliver, Ramon

    2010-11-20

    Quasi-biennial oscillations (QBOs) are frequently observed in solar activity indices. However, no clear physical mechanism for the observed variations has been suggested so far. Here, we study the stability of magnetic Rossby waves in the solar tachocline using the shallow water magnetohydrodynamic approximation. Our analysis shows that the combination of typical differential rotation and a toroidal magnetic field with a strength of {>=}10{sup 5} G triggers the instability of the m = 1 magnetic Rossby wave harmonic with a period of {approx}2 years. This harmonic is antisymmetric with respect to the equator and its period (and growth rate) depends onmore » the differential rotation parameters and magnetic field strength. The oscillations may cause a periodic magnetic flux emergence at the solar surface and consequently may lead to the observed QBO in solar activity features. The period of QBOs may change throughout a cycle, and from cycle to cycle, due to variations of the mean magnetic field and differential rotation in the tachocline.« less

  11. A linearization time-domain CMOS smart temperature sensor using a curvature compensation oscillator.

    PubMed

    Chen, Chun-Chi; Chen, Hao-Wen

    2013-08-28

    This paper presents an area-efficient time-domain CMOS smart temperature sensor using a curvature compensation oscillator for linearity enhancement with a -40 to 120 °C temperature range operability. The inverter-based smart temperature sensors can substantially reduce the cost and circuit complexity of integrated temperature sensors. However, a large curvature exists on the temperature-to-time transfer curve of the inverter-based delay line and results in poor linearity of the sensor output. For cost reduction and error improvement, a temperature-to-pulse generator composed of a ring oscillator and a time amplifier was used to generate a thermal sensing pulse with a sufficient width proportional to the absolute temperature (PTAT). Then, a simple but effective on-chip curvature compensation oscillator is proposed to simultaneously count and compensate the PTAT pulse with curvature for linearization. With such a simple structure, the proposed sensor possesses an extremely small area of 0.07 mm2 in a TSMC 0.35-mm CMOS 2P4M digital process. By using an oscillator-based scheme design, the proposed sensor achieves a fine resolution of 0.045 °C without significantly increasing the circuit area. With the curvature compensation, the inaccuracy of -1.2 to 0.2 °C is achieved in an operation range of -40 to 120 °C after two-point calibration for 14 packaged chips. The power consumption is measured as 23 mW at a sample rate of 10 samples/s.

  12. Flow and clog in a silo with oscillating exit

    NASA Astrophysics Data System (ADS)

    To, Kiwing; Tai, Hsiang-Ting

    2017-09-01

    When grains flow out of a silo, flow rate W increases with exit size D . If D is too small, an arch may form and the flow may be blocked at the exit. To recover from clogging, the arch has to be destroyed. Here we construct a two-dimensional silo with movable exit and study the effects of exit oscillation (with amplitude A and frequency f ) on flow rate, clogging, and unclogging of grains through the exit. We find that, if exit oscillates, W remains finite even when D (measured in unit of grain diameter) is only slightly larger than one. Surprisingly, while W increases with oscillation strength Γ ≡4 π2A f2 as expected at small D , W decreases with Γ when D ≥5 due to induced random motion of the grains at the exit. When D is small and oscillation speed v ≡2 π A f is slow, temporary clogging events cause the grains to flow intermittently. In this regime, W depends only on v —a feature consistent to a simple arch breaking mechanism, and the phase boundary of intermittent flow in the D -v plane is consistent to either a power law: D ∝v-7 or an exponential form: D ∝e-D /0.55 . Furthermore, the flow time statistic is Poissonian whereas the recovery time statistic follows a power-law distribution.

  13. Time-series modeling and prediction of global monthly absolute temperature for environmental decision making

    NASA Astrophysics Data System (ADS)

    Ye, Liming; Yang, Guixia; Van Ranst, Eric; Tang, Huajun

    2013-03-01

    A generalized, structural, time series modeling framework was developed to analyze the monthly records of absolute surface temperature, one of the most important environmental parameters, using a deterministicstochastic combined (DSC) approach. Although the development of the framework was based on the characterization of the variation patterns of a global dataset, the methodology could be applied to any monthly absolute temperature record. Deterministic processes were used to characterize the variation patterns of the global trend and the cyclic oscillations of the temperature signal, involving polynomial functions and the Fourier method, respectively, while stochastic processes were employed to account for any remaining patterns in the temperature signal, involving seasonal autoregressive integrated moving average (SARIMA) models. A prediction of the monthly global surface temperature during the second decade of the 21st century using the DSC model shows that the global temperature will likely continue to rise at twice the average rate of the past 150 years. The evaluation of prediction accuracy shows that DSC models perform systematically well against selected models of other authors, suggesting that DSC models, when coupled with other ecoenvironmental models, can be used as a supplemental tool for short-term (˜10-year) environmental planning and decision making.

  14. Thermal decay of Coulomb blockade oscillations

    NASA Astrophysics Data System (ADS)

    Idrisov, Edvin G.; Levkivskyi, Ivan P.; Sukhorukov, Eugene V.

    2017-10-01

    We study transport properties and the charge quantization phenomenon in a small metallic island connected to the leads through two quantum point contacts (QPCs). The linear conductance is calculated perturbatively with respect to weak tunneling and weak backscattering at QPCs as a function of the temperature T and gate voltage. The conductance shows Coulomb blockade (CB) oscillations as a function of the gate voltage that decay with the temperature as a result of thermally activated fluctuations of the charge in the island. The regimes of quantum T ≪EC and thermal T ≫EC fluctuations are considered, where EC is the charging energy of an isolated island. Our predictions for CB oscillations in the quantum regime coincide with previous findings by Furusaki and Matveev [Phys. Rev. B 52, 16676 (1995), 10.1103/PhysRevB.52.16676]. In the thermal regime the visibility of Coulomb blockade oscillations decays with the temperature as √{T /EC }exp(-π2T /EC) , where the exponential dependence originates from the thermal averaging over the instant charge fluctuations, while the prefactor has a quantum origin. This dependence does not depend on the strength of couplings to the leads. The differential capacitance, calculated in the case of a single tunnel junction, shows the same exponential decay, however the prefactor is linear in the temperature. This difference can be attributed to the nonlocality of the quantum effects. Our results agree with the recent experiment [Nature (London) 536, 58 (2016), 10.1038/nature19072] in the whole range of the parameter T /EC .

  15. Stellar laboratories. IV. New Ga iv, Ga v, and Ga vi oscillator strengths and the gallium abundance in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.

    2015-05-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, advanced non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These atmospheres are strongly dependent on the reliability of the atomic data that are used to calculate them. Aims: Reliable Ga iv-vi oscillator strengths are used to identify Ga lines in the spectra of the DA-type white dwarf G191-B2B and the DO-type white dwarf RE 0503-289 and to determine their photospheric Ga abundances. Methods: We newly calculated Ga iv-vi oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for analyzing of Ga lines exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: We unambiguously detected 20 isolated and 6 blended (with lines of other species) Ga v lines in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of RE 0503-289. The identification of Ga iv and Ga vi lines is uncertain because they are weak and partly blended by other lines. The determined Ga abundance is 3.5 ± 0.5 × 10-5 (mass fraction, about 625 times the solar value). The Ga iv/Ga v ionization equilibrium, which is a very sensitive indicator for the effective temperature, is well reproduced in RE 0503-289. We identified the strongest Ga iv lines (at 1258.801, 1338.129 Å) in the HST/STIS spectrum of G191-B2B and measured a Ga abundance of 2.0 ± 0.5 × 10-6 (about 22 times solar). Conclusions: Reliable measurements and calculations of atomic data are a prerequisite for stellar-atmosphere modeling. The observed Ga iv-v line profiles in two white dwarf (G191-B2B and RE 0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. For the first time, this allowed us to determine the photospheric Ga abundance in white dwarfs. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space

  16. Forecasting Error Calculation with Mean Absolute Deviation and Mean Absolute Percentage Error

    NASA Astrophysics Data System (ADS)

    Khair, Ummul; Fahmi, Hasanul; Hakim, Sarudin Al; Rahim, Robbi

    2017-12-01

    Prediction using a forecasting method is one of the most important things for an organization, the selection of appropriate forecasting methods is also important but the percentage error of a method is more important in order for decision makers to adopt the right culture, the use of the Mean Absolute Deviation and Mean Absolute Percentage Error to calculate the percentage of mistakes in the least square method resulted in a percentage of 9.77% and it was decided that the least square method be worked for time series and trend data.

  17. Coordinated infraslow neural and cardiac oscillations mark fragility and offline periods in mammalian sleep

    PubMed Central

    Lecci, Sandro; Fernandez, Laura M. J.; Weber, Frederik D.; Cardis, Romain; Chatton, Jean-Yves; Born, Jan; Lüthi, Anita

    2017-01-01

    Rodents sleep in bouts lasting minutes; humans sleep for hours. What are the universal needs served by sleep given such variability? In sleeping mice and humans, through monitoring neural and cardiac activity (combined with assessment of arousability and overnight memory consolidation, respectively), we find a previously unrecognized hallmark of sleep that balances two fundamental yet opposing needs: to maintain sensory reactivity to the environment while promoting recovery and memory consolidation. Coordinated 0.02-Hz oscillations of the sleep spindle band, hippocampal ripple activity, and heart rate sequentially divide non–rapid eye movement (non-REM) sleep into offline phases and phases of high susceptibility to external stimulation. A noise stimulus chosen such that sleeping mice woke up or slept through at comparable rates revealed that offline periods correspond to raising, whereas fragility periods correspond to declining portions of the 0.02-Hz oscillation in spindle activity. Oscillations were present throughout non-REM sleep in mice, yet confined to light non-REM sleep (stage 2) in humans. In both species, the 0.02-Hz oscillation predominated over posterior cortex. The strength of the 0.02-Hz oscillation predicted superior memory recall after sleep in a declarative memory task in humans. These oscillations point to a conserved function of mammalian non-REM sleep that cycles between environmental alertness and internal memory processing in 20- to 25-s intervals. Perturbed 0.02-Hz oscillations may cause memory impairment and ill-timed arousals in sleep disorders. PMID:28246641

  18. Theoretical prediction of pullout strengths for dental and orthopaedic screws with conical profile and buttress threads.

    PubMed

    Shih, Kao-Shang; Hou, Sheng-Mou; Lin, Shang-Chih

    2017-12-01

    The pullout strength of a screw is an indicator of how secure bone fragments are being held in place. Such bone-purchasing ability is sensitive to bone quality, thread design, and the pilot hole, and is often evaluated by experimental and numerical methods. Historically, there are some mathematical formulae to simulate the screw withdrawal from the synthetic bone. There are great variations in screw specifications. However, extensive investigation of the correlation between experimental and analytical results has not been reported in literature. Referring to the literature formulae, this study aims to evaluate the differences in the calculated pullout strengths. The pullout tests of the surgical screws are measured and the sawbone is used as the testing block. The absolute errors and correlation coefficients of the experimental and analytical results are calculated as the comparison baselines of the formulae. The absolute error of the dental, traumatic, and spinal groups are 21.7%, 95.5%, and 37.0%, respectively. For the screws with a conical profile and/or tiny threads, the calculated and measured results are not well correlated. The formulae are not accurate indicators of the pullout strengths of the screws where the design parameters are slightly varied. However, the experimental and numerical results are highly correlated for the cylindrical screws. The pullout strength of a conical screw is higher than that of its counterpart, but all formulae consistently predict the opposite results. In general, the bony purchase of the buttress threads is securer than that of the symmetric thread. An absolute error of up to 51.4% indicates the theoretical results cannot predict the actual value of the pullout strength. Only thread diameter, pitch, and depth are considered in the investigated formulae. The thread profile and shape should be formulated to modify the slippage mechanism at the bone-screw interfaces and simulate the strength change in the squeezed bones

  19. Glucose Oscillations Can Activate an Endogenous Oscillator in Pancreatic Islets

    PubMed Central

    Mukhitov, Nikita; Roper, Michael G.; Bertram, Richard

    2016-01-01

    Pancreatic islets manage elevations in blood glucose level by secreting insulin into the bloodstream in a pulsatile manner. Pulsatile insulin secretion is governed by islet oscillations such as bursting electrical activity and periodic Ca2+ entry in β-cells. In this report, we demonstrate that although islet oscillations are lost by fixing a glucose stimulus at a high concentration, they may be recovered by subsequently converting the glucose stimulus to a sinusoidal wave. We predict with mathematical modeling that the sinusoidal glucose signal’s ability to recover islet oscillations depends on its amplitude and period, and we confirm our predictions by conducting experiments with islets using a microfluidics platform. Our results suggest a mechanism whereby oscillatory blood glucose levels recruit non-oscillating islets to enhance pulsatile insulin output from the pancreas. Our results also provide support for the main hypothesis of the Dual Oscillator Model, that a glycolytic oscillator endogenous to islet β-cells drives pulsatile insulin secretion. PMID:27788129

  20. Reliability of the Q Force; a mobile instrument for measuring isometric quadriceps muscle strength.

    PubMed

    Douma, K W; Regterschot, G R H; Krijnen, W P; Slager, G E C; van der Schans, C P; Zijlstra, W

    2016-01-01

    The ability to generate muscle strength is a pre-requisite for all human movement. Decreased quadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various degrees of extension. Measurements between 110 and 130° extension present the highest values and the most significant increase after training. The objective of this study is to determine the test-retest reliability of muscle strength measurements by the Q Force in older adults in 110° extension. Forty-one healthy older adults, 13 males and 28 females were included in the study. Mean (SD) age was 81.9 (4.89) years. Isometric muscle strength of the Quadriceps muscle was assessed with the Q Force at 110° of knee extension. Participants were measured at two sessions with a three to eight day interval between sessions. To determine relative reliability, the intraclass correlation coefficient (ICC) was calculated. To determine absolute reliability, Bland and Altman Limits of Agreement (LOA) were calculated and t-tests were performed. Relative reliability of the Q Force is good to excellent as all ICC coefficients are higher than 0.75. Generally a large 95 % LOA, reflecting only moderate absolute reliability, is found as exemplified for the peak torque left leg of -18.6 N to 33.8 N and the right leg of -9.2 N to 26.4 N was between 15.7 and 23.6 Newton representing 25.2 % to 39.9 % of the size of the mean. Small systematic differences in mean were found between measurement session 1 and 2. The present study shows that the Q Force has excellent relative test-retest reliability, but limited absolute test-retest reliability. Since the Q Force is relatively cheap and mobile it is suitable for

  1. 20 CFR 404.1205 - Absolute coverage groups.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Absolute coverage groups. 404.1205 Section... INSURANCE (1950- ) Coverage of Employees of State and Local Governments What Groups of Employees May Be Covered § 404.1205 Absolute coverage groups. (a) General. An absolute coverage group is a permanent...

  2. 20 CFR 404.1205 - Absolute coverage groups.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Absolute coverage groups. 404.1205 Section... INSURANCE (1950- ) Coverage of Employees of State and Local Governments What Groups of Employees May Be Covered § 404.1205 Absolute coverage groups. (a) General. An absolute coverage group is a permanent...

  3. 20 CFR 404.1205 - Absolute coverage groups.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Absolute coverage groups. 404.1205 Section... INSURANCE (1950- ) Coverage of Employees of State and Local Governments What Groups of Employees May Be Covered § 404.1205 Absolute coverage groups. (a) General. An absolute coverage group is a permanent...

  4. From cosmology to cold atoms: observation of Sakharov oscillations in a quenched atomic superfluid.

    PubMed

    Hung, Chen-Lung; Gurarie, Victor; Chin, Cheng

    2013-09-13

    Predicting the dynamics of many-body systems far from equilibrium is a challenging theoretical problem. A long-predicted phenomenon in hydrodynamic nonequilibrium systems is the occurrence of Sakharov oscillations, which manifest in the anisotropy of the cosmic microwave background and the large-scale correlations of galaxies. Here, we report the observation of Sakharov oscillations in the density fluctuations of a quenched atomic superfluid through a systematic study in both space and time domains and with tunable interaction strengths. Our work suggests a different approach to the study of nonequilibrium dynamics of quantum many-body systems and the exploration of their analogs in cosmology and astrophysics.

  5. Coupled opto-electronic oscillator

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor); Maleki, Lute (Inventor)

    1999-01-01

    A coupled opto-electronic oscillator that directly couples a laser oscillation with an electronic oscillation to simultaneously achieve a stable RF oscillation at a high frequency and ultra-short optical pulsation by mode locking with a high repetition rate and stability. Single-mode selection can be achieved even with a very long opto-electronic loop. A multimode laser can be used to pump the electronic oscillation, resulting in a high operation efficiency. The optical and the RF oscillations are correlated to each other.

  6. Plasma Oscillation Characterization of NASA's HERMeS Hall Thruster via High Speed Imaging

    NASA Technical Reports Server (NTRS)

    Huang, Wensheng; Kamhawi, Hani; Haag, Thomas W.

    2016-01-01

    The performance and facility effect characterization tests of NASA's 12.5-kW Hall Effect Rocket with Magnetic Shielding had been completed. As a part of these tests, three plasma oscillation characterization studies were performed to help determine operation settings and quantify margins. The studies included the magnetic field strength variation study, background pressure effect study, and cathode flow fraction study. Separate high-speed videos of the thruster including the cathode and of only the cathode were recorded. Breathing mode at 10-15 kHz and cathode gradient-driven mode at 60-75 kHz were observed. An additional high frequency (40-70 kHz) global oscillation mode with sinusoidal probability distribution function was identified.

  7. Parametric Oscillation, Frequency Mixing, and Injection Locking of Strongly Coupled Nanomechanical Resonator Modes.

    PubMed

    Seitner, Maximilian J; Abdi, Mehdi; Ridolfo, Alessandro; Hartmann, Michael J; Weig, Eva M

    2017-06-23

    We study locking phenomena of two strongly coupled, high quality factor nanomechanical resonator modes to a common parametric drive at a single drive frequency in different parametric driving regimes. By controlled dielectric gradient forces we tune the resonance frequencies of the flexural in-plane and out-of-plane oscillation of the high stress silicon nitride string through their mutual avoided crossing. For the case of the strong common parametric drive signal-idler generation via nondegenerate parametric two-mode oscillation is observed. Broadband frequency tuning of the very narrow linewidth signal and idler resonances is demonstrated. When the resonance frequencies of the signal and idler get closer to each other, partial injection locking, injection pulling, and complete injection locking to half of the drive frequency occurs depending on the pump strength. Furthermore, satellite resonances, symmetrically offset from the signal and idler by their beat note, are observed, which can be attributed to degenerate four-wave mixing in the highly nonlinear mechanical oscillations.

  8. Various oscillation patterns in phase models with locally attractive and globally repulsive couplings.

    PubMed

    Sato, Katsuhiko; Shima, Shin-ichiro

    2015-10-01

    We investigate a phase model that includes both locally attractive and globally repulsive coupling in one dimension. This model exhibits nontrivial spatiotemporal patterns that have not been observed in systems that contain only local or global coupling. Depending on the relative strengths of the local and global coupling and on the form of global coupling, the system can show a spatially uniform state (in-phase synchronization), a monotonically increasing state (traveling wave), and three types of oscillations of relative phase difference. One of the oscillations of relative phase difference has the characteristic of being locally unstable but globally attractive. That is, any small perturbation to the periodic orbit in phase space destroys its periodic motion, but after a long time the system returns to the original periodic orbit. This behavior is closely related to the emergence of saddle two-cluster states for global coupling only, which are connected to each other by attractive heteroclinic orbits. The mechanism of occurrence of this type of oscillation is discussed.

  9. Synchrotron oscillation effects on an rf-solenoid spin resonance

    NASA Astrophysics Data System (ADS)

    Benati, P.; Chiladze, D.; Dietrich, J.; Gaisser, M.; Gebel, R.; Guidoboni, G.; Hejny, V.; Kacharava, A.; Kamerdzhiev, V.; Kulessa, P.; Lehrach, A.; Lenisa, P.; Lorentz, B.; Maier, R.; Mchedlishvili, D.; Morse, W. M.; Öllers, D.; Pesce, A.; Polyanskiy, A.; Prasuhn, D.; Rathmann, F.; Semertzidis, Y. K.; Stephenson, E. J.; Stockhorst, H.; Ströher, H.; Talman, R.; Valdau, Yu.; Weidemann, Ch.; Wüstner, P.

    2012-12-01

    New measurements are reported for the time dependence of the vertical polarization of a 0.97GeV/c deuteron beam circulating in a storage ring and perturbed by an rf solenoid. The storage ring is the cooler synchrotron (COSY) located at the Forschungszentrum Jülich. The beam polarization was measured continuously using a 1.5 cm thick carbon target located at the edge of the circulating deuteron beam and the scintillators of the EDDA detector. An rf solenoid mounted on the ring was used to generate fields at and near the frequency of the 1-Gγ spin resonance. Measurements were made of the vertical beam polarization as a function of time with the operation of the rf solenoid in either fixed or continuously variable frequency mode. Using rf-solenoid strengths as large as 2.66×10-5revolutions/turn, slow oscillations (˜1Hz) were observed in the vertical beam polarization. When the circulating beam was continuously electron cooled, these oscillations completely reversed the polarization and showed no sign of diminishing in amplitude. But for the uncooled beam, the oscillation amplitude was damped to nearly zero within a few seconds. A simple spin-tracking model without the details of the COSY ring lattice was successful in reproducing these oscillations and demonstrating the sensitivity of the damping to the magnitude of the synchrotron motion of the beam particles. The model demonstrates that the characteristic features of measurements made in the presence of large synchrotron oscillations are distinct from the features of such measurements when made off resonance. These data were collected in preparation for a study of the spin coherence time, a beam property that needs to become long to enable a search for an electric dipole moment using a storage ring.

  10. A robust and tunable mitotic oscillator in artificial cells

    PubMed Central

    Wang, Shiyuan; Barnes, Patrick M; Liu, Xuwen; Xu, Haotian; Jin, Minjun; Liu, Allen P

    2018-01-01

    Single-cell analysis is pivotal to deciphering complex phenomena like heterogeneity, bistability, and asynchronous oscillations, where a population ensemble cannot represent individual behaviors. Bulk cell-free systems, despite having unique advantages of manipulation and characterization of biochemical networks, lack the essential single-cell information to understand a class of out-of-steady-state dynamics including cell cycles. Here, by encapsulating Xenopus egg extracts in water-in-oil microemulsions, we developed artificial cells that are adjustable in sizes and periods, sustain mitotic oscillations for over 30 cycles, and function in forms from the simplest cytoplasmic-only to the more complicated ones involving nuclear dynamics, mimicking real cells. Such innate flexibility and robustness make it key to studying clock properties like tunability and stochasticity. Our results also highlight energy as an important regulator of cell cycles. We demonstrate a simple, powerful, and likely generalizable strategy of integrating strengths of single-cell approaches into conventional in vitro systems to study complex clock functions. PMID:29620527

  11. Power oscillator

    DOEpatents

    Gitsevich, Aleksandr

    2001-01-01

    An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  12. Self-oscillation in spin torque oscillator stabilized by field-like torque

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

    Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi

    2014-04-14

    The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation.

  13. On the stability analysis of a pair of van der Pol oscillators with delayed self-connection, position and velocity couplings

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

    Hu, Kun; Department of Mathematics, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon; Chung, Kwok-wai, E-mail: makchung@cityu.edu.hk

    2013-11-15

    In this paper, we perform a stability analysis of a pair of van der Pol oscillators with delayed self-connection, position and velocity couplings. Bifurcation diagram of the damping, position and velocity coupling strengths is constructed, which gives insight into how stability boundary curves come into existence and how these curves evolve from small closed loops into open-ended curves. The van der Pol oscillator has been considered by many researchers as the nodes for various networks. It is inherently unstable at the zero equilibrium. Stability control of a network is always an important problem. Currently, the stabilization of the zero equilibriummore » of a pair of van der Pol oscillators can be achieved only for small damping strength by using delayed velocity coupling. An interesting question arises naturally: can the zero equilibrium be stabilized for an arbitrarily large value of the damping strength? We prove that it can be. In addition, a simple condition is given on how to choose the feedback parameters to achieve such goal. We further investigate how the in-phase mode or the out-of-phase mode of a periodic solution is related to the stability boundary curve that it emerges from a Hopf bifurcation. Analytical expression of a periodic solution is derived using an integration method. Some illustrative examples show that the theoretical prediction and numerical simulation are in good agreement.« less

  14. Variance computations for functional of absolute risk estimates.

    PubMed

    Pfeiffer, R M; Petracci, E

    2011-07-01

    We present a simple influence function based approach to compute the variances of estimates of absolute risk and functions of absolute risk. We apply this approach to criteria that assess the impact of changes in the risk factor distribution on absolute risk for an individual and at the population level. As an illustration we use an absolute risk prediction model for breast cancer that includes modifiable risk factors in addition to standard breast cancer risk factors. Influence function based variance estimates for absolute risk and the criteria are compared to bootstrap variance estimates.

  15. Variance computations for functional of absolute risk estimates

    PubMed Central

    Pfeiffer, R.M.; Petracci, E.

    2011-01-01

    We present a simple influence function based approach to compute the variances of estimates of absolute risk and functions of absolute risk. We apply this approach to criteria that assess the impact of changes in the risk factor distribution on absolute risk for an individual and at the population level. As an illustration we use an absolute risk prediction model for breast cancer that includes modifiable risk factors in addition to standard breast cancer risk factors. Influence function based variance estimates for absolute risk and the criteria are compared to bootstrap variance estimates. PMID:21643476

  16. Mass and Radius Constraints Using Magnetar Giant Flare Oscillations

    NASA Astrophysics Data System (ADS)

    Deibel, Alex T.; Steiner, A. W.; Brown, E. F.

    2013-04-01

    We extend the study of oscillating neutron stars to include observed magnetic field strengths. The strong magnetic field will alter the equilibrium composition of the outer neutron star crust. We construct a new neutron star crust model which predicts nuclear masses with an accuracy very close to that of the Finite Range Droplet Model. The mass model for equilibrium nuclei also includes recent developments in the nuclear physics, in particular, shell corrections and an updated neutron-drip line. We perturb our crust model to predict axial crust modes and assign them to observed giant flare quasi-periodic oscillation (QPO) frequencies from SGR 1806-20. The QPOs associated with the fundamental and harmonic crust modes can be used to constrain magnetar masses and radii. We use these modes and the phenomenological equations of state from Steiner et al. to find a magnetar crust which reproduces observations of SGR 1806-20. We find magnetar crusts which match observations for various magnetic field strengths and values of entrainment of the free neutron gas in the inner crust. For a crust without a magnetic field we obtain the approximate values of M = 1.35 Msun and R = 11.85 km. For a magnetized crust with the surface dipole field of SGR 1806-20 we obtain the approximate values of M = 1.25 Msun and R = 12.41 km. If there is less entrainment of the free neutron gas the magnetar requires a larger mass and radius to reproduce observations.

  17. Nonlinear dynamics of a magnetically driven Duffing-type spring-magnet oscillator in the static magnetic field of a coil

    NASA Astrophysics Data System (ADS)

    Donoso, Guillermo; Ladera, Celso L.

    2012-11-01

    We study the nonlinear oscillations of a forced and weakly dissipative spring-magnet system moving in the magnetic fields of two fixed coaxial, hollow induction coils. As the first coil is excited with a dc current, both a linear and a cubic magnet-position dependent force appear on the magnet-spring system. The second coil, located below the first, excited with an ac current, provides the oscillating magnetic driving force on the system. From the magnet-coil interactions, we obtain, analytically, the nonlinear motion equation of the system, found to be a forced and damped cubic Duffing oscillator moving in a quartic potential. The relative strengths of the coefficients of the motion equation can be easily set by varying the coils’ dc and ac currents. We demonstrate, theoretically and experimentally, the nonlinear behaviour of this oscillator, including its oscillation modes and nonlinear resonances, the fold-over effect, the hysteresis and amplitude jumps, and its chaotic behaviour. It is an oscillating system suitable for teaching an advanced experiment in nonlinear dynamics both at senior undergraduate and graduate levels.

  18. The search for instantaneous vection: An oscillating visual prime reduces vection onset latency.

    PubMed

    Palmisano, Stephen; Riecke, Bernhard E

    2018-01-01

    Typically it takes up to 10 seconds or more to induce a visual illusion of self-motion ("vection"). However, for this vection to be most useful in virtual reality and vehicle simulation, it needs to be induced quickly, if not immediately. This study examined whether vection onset latency could be reduced towards zero using visual display manipulations alone. In the main experiments, visual self-motion simulations were presented to observers via either a large external display or a head-mounted display (HMD). Priming observers with visually simulated viewpoint oscillation for just ten seconds before the main self-motion display was found to markedly reduce vection onset latencies (and also increase ratings of vection strength) in both experiments. As in earlier studies, incorporating this simulated viewpoint oscillation into the self-motion displays themselves was also found to improve vection. Average onset latencies were reduced from 8-9s in the no oscillating control condition to as little as 4.6 s (for external displays) or 1.7 s (for HMDs) in the combined oscillation condition (when both the visual prime and the main self-motion display were oscillating). As these display manipulations did not appear to increase the likelihood or severity of motion sickness in the current study, they could possibly be used to enhance computer generated simulation experiences and training in the future, at no additional cost.

  19. The search for instantaneous vection: An oscillating visual prime reduces vection onset latency

    PubMed Central

    Riecke, Bernhard E.

    2018-01-01

    Typically it takes up to 10 seconds or more to induce a visual illusion of self-motion (“vection”). However, for this vection to be most useful in virtual reality and vehicle simulation, it needs to be induced quickly, if not immediately. This study examined whether vection onset latency could be reduced towards zero using visual display manipulations alone. In the main experiments, visual self-motion simulations were presented to observers via either a large external display or a head-mounted display (HMD). Priming observers with visually simulated viewpoint oscillation for just ten seconds before the main self-motion display was found to markedly reduce vection onset latencies (and also increase ratings of vection strength) in both experiments. As in earlier studies, incorporating this simulated viewpoint oscillation into the self-motion displays themselves was also found to improve vection. Average onset latencies were reduced from 8-9s in the no oscillating control condition to as little as 4.6 s (for external displays) or 1.7 s (for HMDs) in the combined oscillation condition (when both the visual prime and the main self-motion display were oscillating). As these display manipulations did not appear to increase the likelihood or severity of motion sickness in the current study, they could possibly be used to enhance computer generated simulation experiences and training in the future, at no additional cost. PMID:29791445

  20. Micromagnetic study of auto-oscillation modes in spin-Hall nano-oscillators

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

    Ulrichs, H., E-mail: henning.ulrichs@uni-muenster.de; Demidov, V. E.; Demokritov, S. O.

    2014-01-27

    We present a numerical study of magnetization dynamics in a recently introduced spin torque nano-oscillator, whose operational principle relies on the spin-Hall effect—spin-Hall nano-oscillators. Our numerical results show good agreement with the experimentally observed behaviors and provide detailed information about the features of the primary auto-oscillation mode observed in the experiments. They also clarify the physical nature of the secondary auto-oscillation mode, which was experimentally observed under certain conditions only.

  1. A Linear Model of Phase-Dependent Power Correlations in Neuronal Oscillations

    PubMed Central

    Eriksson, David; Vicente, Raul; Schmidt, Kerstin

    2011-01-01

    Recently, it has been suggested that effective interactions between two neuronal populations are supported by the phase difference between the oscillations in these two populations, a hypothesis referred to as “communication through coherence” (CTC). Experimental work quantified effective interactions by means of the power correlations between the two populations, where power was calculated on the local field potential and/or multi-unit activity. Here, we present a linear model of interacting oscillators that accounts for the phase dependency of the power correlation between the two populations and that can be used as a reference for detecting non-linearities such as gain control. In the experimental analysis, trials were sorted according to the coupled phase difference of the oscillators while the putative interaction between oscillations was taking place. Taking advantage of the modeling, we further studied the dependency of the power correlation on the uncoupled phase difference, connection strength, and topology. Since the uncoupled phase difference, i.e., the phase relation before the effective interaction, is the causal variable in the CTC hypothesis we also describe how power correlations depend on that variable. For uni-directional connectivity we observe that the width of the uncoupled phase dependency is broader than for the coupled phase. Furthermore, the analytical results show that the characteristics of the phase dependency change when a bidirectional connection is assumed. The width of the phase dependency indicates which oscillation frequencies are optimal for a given connection delay distribution. We propose that a certain width enables a stimulus-contrast dependent extent of effective long-range lateral connections. PMID:21808618

  2. Dipole strength distributions from HIGS Experiments

    NASA Astrophysics Data System (ADS)

    Werner, V.; Cooper, N.; Goddard, P. M.; Humby, P.; Ilieva, R. S.; Rusev, G.; Beller, J.; Bernards, C.; Crider, B. P.; Isaak, J.; Kelley, J. H.; Kwan, E.; Löher, B.; Peters, E. E.; Pietralla, N.; Romig, C.; Savran, D.; Scheck, M.; Tonchev, A. P.; Tornow, W.; Yates, S. W.; Zweidinger, M.

    2015-05-01

    A series of photon scattering experiments has been performed on the double-beta decay partners 76Ge and 76Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesis

  3. Pulse-coupled mixed-mode oscillators: Cluster states and extreme noise sensitivity

    NASA Astrophysics Data System (ADS)

    Karamchandani, Avinash J.; Graham, James N.; Riecke, Hermann

    2018-04-01

    Motivated by rhythms in the olfactory system of the brain, we investigate the synchronization of all-to-all pulse-coupled neuronal oscillators exhibiting various types of mixed-mode oscillations (MMOs) composed of sub-threshold oscillations (STOs) and action potentials ("spikes"). We focus particularly on the impact of the delay in the interaction. In the weak-coupling regime, we reduce the system to a Kuramoto-type equation with non-sinusoidal phase coupling and the associated Fokker-Planck equation. Its linear stability analysis identifies the appearance of various cluster states. Their type depends sensitively on the delay and the width of the pulses. Interestingly, long delays do not imply slow population rhythms, and the number of emerging clusters only loosely depends on the number of STOs. Direct simulations of the oscillator equations reveal that for quantitative agreement of the weak-coupling theory the coupling strength and the noise have to be extremely small. Even moderate noise leads to significant skipping of STO cycles, which can enhance the diffusion coefficient in the Fokker-Planck equation by two orders of magnitude. Introducing an effective diffusion coefficient extends the range of agreement significantly. Numerical simulations of the Fokker-Planck equation reveal bistability and solutions with oscillatory order parameters that result from nonlinear mode interactions. These are confirmed in simulations of the full spiking model.

  4. Bipolaron assisted Bloch-like oscillations in organic lattices

    NASA Astrophysics Data System (ADS)

    Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo

    2017-06-01

    The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.

  5. FOREWORD: 4th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas

    NASA Astrophysics Data System (ADS)

    Leckrone, David S.; Sugar, Jack

    1993-01-01

    In 1983 the Atomic Spectroscopy Group at the University of Lund organized a conference at Lund the purpose of which was to establish a dialogue between scientists whose research made use of basic atomic data, and scientists whose research produced such data. The data in question include complete descriptions of atomic and ionic spectra, accurate transition wavelengths and relative intensities, energy levels, lifetimes, oscillator strengths, line shapes, and nuclear effects (hyperfine structure and isotope shifts). The "consumers" in urgent need of new or improved atomic data included astrophysicsts, laboratory plasma physicists, and spectrochemists. The synergism between these specialists and the theoretical and experimental atomic physicists resulted in a highly successful meeting, attended by approximately 70 people. The rapid advances foreseen at that time in all of these areas of observational, experimental and theoretical science stimulated planning for a second conference on this subject in 1986 at the University of Toledo, and subsequently a third meeting was held at the Royal Netherlands Academy of Arts and Sciences in Amsterdam in 1989. Again attendance at the latter two meetings totaled approximately 70 researchers. The participants in Amsterdam agreed to re-convene at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, in 1992, maintaining the frequency of these conferences at one every three years. The present Topical Issue of Physica Scripta consists of 31 invited reviews given at the Gaithersburg meeting. Extended abstracts of 63 poster papers from the meeting are being published in NIST Special Publication SP850. Approximately 170 scientists attended the Gaithersburg conference, representing a substantial growth in the size of meetings in this series. One session of the conference was devoted to an informal workshop, at which any participant could give a brief oral statement about his or her most immediate data need

  6. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  7. Electron impact excitation of the electronic states of N2. III - Transitions in the 12.5-14.2-eV energy-loss region at incident energies of 40 and 60 eV

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Trajmar, S.; Cartwright, D. C.

    1977-01-01

    Analysis of electron energy-loss data at incident electron energies of 40 and 60 eV has led to the determination of normalized absolute differential cross sections for electron-impact excitation of five optically-allowed singlet states, two known triplet states, and two unknown triplet-like states of N2, lying in the energy-loss range 12.5-14.2 eV. The range of scattering angles was 5 to 138 deg. The optically allowed transitions and the known triplet excitations are identified. Cross sections for excitation to two unidentified triplet-like states at 13.155 and 13.395 eV were also obtained. The relationship of the generalized oscillator strength for the dipole-allowed states obtained from the described data to known optical oscillator strengths is discussed.

  8. The influence of cooling forearm/hand and gender on estimation of handgrip strength.

    PubMed

    Cheng, Chih-Chan; Shih, Yuh-Chuan; Tsai, Yue-Jin; Chi, Chia-Fen

    2014-01-01

    Handgrip strength is essential in manual operations and activities of daily life, but the influence of forearm/hand skin temperature on estimation of handgrip strength is not well documented. Therefore, the present study intended to investigate the effect of local cooling of the forearm/hand on estimation of handgrip strength at various target force levels (TFLs, in percentage of MVC) for both genders. A cold pressor test was used to lower and maintain the hand skin temperature at 14°C for comparison with the uncooled condition. A total of 10 male and 10 female participants were recruited. The results indicated that females had greater absolute estimation deviations. In addition, both genders had greater absolute deviations in the middle range of TFLs. Cooling caused an underestimation of grip strength. Furthermore, a power function is recommended for establishing the relationship between actual and estimated handgrip force. Statement of relevance: Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Practitioner Summary: It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the

  9. Patterns of patterns of synchronization: Noise induced attractor switching in rings of coupled nonlinear oscillators

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

    Emenheiser, Jeffrey; Department of Physics, University of California, Davis, California 95616; Chapman, Airlie

    Following the long-lived qualitative-dynamics tradition of explaining behavior in complex systems via the architecture of their attractors and basins, we investigate the patterns of switching between distinct trajectories in a network of synchronized oscillators. Our system, consisting of nonlinear amplitude-phase oscillators arranged in a ring topology with reactive nearest-neighbor coupling, is simple and connects directly to experimental realizations. We seek to understand how the multiple stable synchronized states connect to each other in state space by applying Gaussian white noise to each of the oscillators' phases. To do this, we first analytically identify a set of locally stable limit cyclesmore » at any given coupling strength. For each of these attracting states, we analyze the effect of weak noise via the covariance matrix of deviations around those attractors. We then explore the noise-induced attractor switching behavior via numerical investigations. For a ring of three oscillators, we find that an attractor-switching event is always accompanied by the crossing of two adjacent oscillators' phases. For larger numbers of oscillators, we find that the distribution of times required to stochastically leave a given state falls off exponentially, and we build an attractor switching network out of the destination states as a coarse-grained description of the high-dimensional attractor-basin architecture.« less

  10. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  11. Predicting the onset of high-frequency self-excited oscillations in a channel with an elastic wall

    NASA Astrophysics Data System (ADS)

    Ward, Thomas; Whittaker, Robert

    2016-11-01

    Flow-induced oscillations of fluid-conveying elastic-walled channels arise in many industrial and biological systems including the oscillation of the vocal cords during phonation. We derive a system of equations that describes the wall displacement in response to the steady and oscillatory components of the fluid pressure derived by Whittaker et al. (2010). We show that the steady pressure component results in a base state deformation assumed to be small in magnitude relative to the length of the channel. The oscillation frequency of the elastic wall is determined by an eigenvalue problem paramterised by the shape of the base state deformation, the strength of axial tension relative to azimuthal bending, F , and the size of non-linear stretching effects from the wall's initial deformation, K . We determine the slow growth or decay of the normal modes in each by considering the energy budget of the system. The amplitude of the oscillations grow or decay exponentially with a growth rate Λ, which may be expressed in terms of a critical Reynolds number Rec . We use numerical simulations to identify three distinct regions in parameter regimes space and determine the stability of oscillations in each.

  12. A Realtime Active Feedback Control System For Coupled Nonlinear Chemical Oscillators

    NASA Astrophysics Data System (ADS)

    Tompkins, Nathan; Fraden, Seth

    2012-02-01

    We study the manipulation and control of oscillatory networks. As a model system we use an emulsion of Belousov-Zhabotinsky (BZ) oscillators packed on a hexagonal lattice. Each drop is observed and perturbed by a Programmable Illumination Microscope (PIM). The PIM allows us to track individual BZ oscillators, calculate the phase and order parameters of every drop, and selectively perturb specific drops with photo illumination, all in realtime. To date we have determined the native attractor patterns for drops in 1D arrays and 2D hexagonal packing as a function of coupling strength as well as determined methods to move the system from one attractor basin to another. Current work involves implementing these attractor control methods with our experimental system and future work will likely include implementing a model neural network for use with photo controllable BZ emulsions.

  13. A narrow-band injection-seeded pulsed titanium:sapphire oscillator-amplifier system with on-line chirp analysis for high-resolution spectroscopy.

    PubMed

    Hannemann, S; van Duijn, E-J; Ubachs, W

    2007-10-01

    A narrow-band tunable injection-seeded pulsed titanium:sapphire laser system has been developed for application in high-resolution spectroscopic studies at the fundamental wavelengths in the near infrared as well as in the ultraviolet, deep ultraviolet, and extreme ultraviolet after upconversion. Special focus is on the quantitative assessment of the frequency characteristics of the oscillator-amplifier system on a pulse-to-pulse basis. Frequency offsets between continuous-wave seed light and the pulsed output are measured as well as linear chirps attributed mainly to mode pulling effects in the oscillator cavity. Operational conditions of the laser are found in which these offset and chirp effects are minimal. Absolute frequency calibration at the megahertz level of accuracy is demonstrated on various atomic and molecular resonance lines.

  14. Adaptive controller for a strength testbed for aircraft structures

    NASA Astrophysics Data System (ADS)

    Laperdin, A. I.; Yurkevich, V. D.

    2017-07-01

    The problem of control system design for a strength testbed of aircraft structures is considered. A method for calculating the parameters of a proportional-integral controller (control algorithm) using the time-scale separation method for the testbed taking into account the dead time effect in the control loop is presented. An adaptive control algorithm structure is proposed which limits the amplitude of high-frequency oscillations in the control system with a change in the direction of motion of the rod of the hydraulic cylinders and provides the desired accuracy and quality of transients at all stages of structural loading history. The results of tests of the developed control system with the adaptive control algorithm on an experimental strength testbed for aircraft structures are given.

  15. Constraining properties of high-density matter in neutron stars with magneto-elastic oscillations

    NASA Astrophysics Data System (ADS)

    Gabler, Michael; Cerdá-Durán, Pablo; Stergioulas, Nikolaos; Font, José A.; Müller, Ewald

    2018-05-01

    We discuss torsional oscillations of highly magnetized neutron stars (magnetars) using two-dimensional, magneto-elastic-hydrodynamical simulations. Our model is able to explain both the low- and high-frequency quasi-periodic oscillations (QPOs) observed in magnetars. The analysis of these oscillations provides constraints on the breakout magnetic-field strength, on the fundamental QPO frequency, and on the frequency of a particularly excited overtone. By performing a new set of simulations, we are able to derive for the first time empirical relations for a self consistent model including a superfluid core which describe these constraints quantitatively. We use these relations to generically constrain properties of high-density matter in neutron stars, employing Bayesian analysis. In spite of current uncertainties and computational approximations, our model-dependent Bayesian posterior estimates for SGR 1806-20 yield a magnetic-field strength \\bar{B}˜ 2.1^{+1.3}_{-1.0}× 10^{15} G and a crust thickness of Δ r = 1.6^{+0.7}_{-0.6} km, which are both in remarkable agreement with observational and theoretical expectations, respectively (1σ error bars are indicated). Our posteriors also favour the presence of a superfluid phase in the core, a relatively low stellar compactness, M/R < 0.19, indicating a relatively stiff equation of state and/or low-mass neutron star, and high shear speeds at the base of the crust, cs > 1.4 × 108 cm s-1. Although the procedure laid out here still has large uncertainties, these constraints could become tighter when additional observations become available.

  16. Observation of the Rabi oscillation of light driven by an atomic spin wave.

    PubMed

    Chen, L Q; Zhang, Guo-Wan; Bian, Cheng-Ling; Yuan, Chun-Hua; Ou, Z Y; Zhang, Weiping

    2010-09-24

    Coherent conversion between a Raman pump field and its Stokes field is observed in a Raman process with a strong atomic spin wave initially prepared by another Raman process operated in the stimulated emission regime. The oscillatory behavior resembles the Rabi oscillation in atomic population in a two-level atomic system driven by a strong light field. The Rabi-like oscillation frequency is found to be related to the strength of the prebuilt atomic spin wave. High conversion efficiency of 40% from the Raman pump field to the Stokes field is recorded and it is independent of the input Raman pump field. This process can act as a photon frequency multiplexer and may find wide applications in quantum information science.

  17. A global algorithm for estimating Absolute Salinity

    NASA Astrophysics Data System (ADS)

    McDougall, T. J.; Jackett, D. R.; Millero, F. J.; Pawlowicz, R.; Barker, P. M.

    2012-12-01

    The International Thermodynamic Equation of Seawater - 2010 has defined the thermodynamic properties of seawater in terms of a new salinity variable, Absolute Salinity, which takes into account the spatial variation of the composition of seawater. Absolute Salinity more accurately reflects the effects of the dissolved material in seawater on the thermodynamic properties (particularly density) than does Practical Salinity. When a seawater sample has standard composition (i.e. the ratios of the constituents of sea salt are the same as those of surface water of the North Atlantic), Practical Salinity can be used to accurately evaluate the thermodynamic properties of seawater. When seawater is not of standard composition, Practical Salinity alone is not sufficient and the Absolute Salinity Anomaly needs to be estimated; this anomaly is as large as 0.025 g kg-1 in the northernmost North Pacific. Here we provide an algorithm for estimating Absolute Salinity Anomaly for any location (x, y, p) in the world ocean. To develop this algorithm, we used the Absolute Salinity Anomaly that is found by comparing the density calculated from Practical Salinity to the density measured in the laboratory. These estimates of Absolute Salinity Anomaly however are limited to the number of available observations (namely 811). In order to provide a practical method that can be used at any location in the world ocean, we take advantage of approximate relationships between Absolute Salinity Anomaly and silicate concentrations (which are available globally).

  18. Oscillator Noise Analysis

    NASA Astrophysics Data System (ADS)

    Demir, Alper

    2005-08-01

    Oscillators are key components of many kinds of systems, particularly electronic and opto-electronic systems. Undesired perturbations, i.e. noise, that exist in practical systems adversely affect the spectral and timing properties of the signals generated by oscillators resulting in phase noise and timing jitter. These are key performance limiting factors, being major contributors to bit-error-rate (BER) of RF and optical communication systems, and creating synchronization problems in clocked and sampled-data electronic systems. In noise analysis for oscillators, the key is figuring out how the various disturbances and noise sources in the oscillator end up as phase fluctuations. In doing so, one first computes transfer functions from the noise sources to the oscillator phase, or the sensitivity of the oscillator phase to these noise sources. In this paper, we first provide a discussion explaining the origins and the proper definition of this transfer or sensitivity function, followed by a critical review of the various numerical techniques for its computation that have been proposed by various authors over the past fifteen years.

  19. An Investigation Into the Relationship Between Maximum Isometric Strength and Vertical Jump Performance.

    PubMed

    Thomas, Christopher; Jones, Paul A; Rothwell, James; Chiang, Chieh Y; Comfort, Paul

    2015-08-01

    Research has demonstrated a clear relationship between dynamic strength and vertical jump (VJ) performance; however, the relationship of isometric strength and VJ performance has been studied less extensively. The aim of this study was to determine the relationship between isometric strength and performance during the squat jump (SJ) and countermovement jump (CMJ). Twenty-two male collegiate athletes (mean ± SD; age = 21.3 ± 2.9 years; height = 175.63 ± 8.23 cm; body mass = 78.06 ± 10.77 kg) performed isometric midthigh pulls (IMTPs) to assess isometric peak force (IPF), maximum rate of force development, and impulse (IMP) (I100, I200, and I300). Force-time data, collected during the VJs, were used to calculate peak velocity, peak force (PF), peak power (PP), and jump height. Absolute IMTP measures of IMP showed the strongest correlations with VJ PF (r = 0.43-0.64; p ≤ 0.05) and VJ PP (r = 0.38-0.60; p ≤ 0.05). No statistical difference was observed in CMJ height (0.33 ± 0.05 m vs. 0.36 ± 0.05 m; p = 0.19; ES = -0.29) and SJ height performance (0.29 ± 0.06 m vs. 0.33 ± 0.05 m; p = 0.14; ES = -0.34) when comparing stronger to weaker athletes. The results of this study illustrate that absolute IPF and IMP are related to VJ PF and PP but not VJ height. Because stronger athletes did not jump higher than weaker athletes, dynamic strength tests may be more practical methods of assessing the relationships between relative strength levels and dynamic performance in collegiate athletes.

  20. Relationship of magnetic field strength and brightness of fine-structure elements in the solar temperature minimum region

    NASA Technical Reports Server (NTRS)

    Cook, J. W.; Ewing, J. A.

    1990-01-01

    A quantitative relationship was determined between magnetic field strength (or magnetic flux) from photospheric magnetograph observations and the brightness temperature of solar fine-structure elements observed at 1600 A, where the predominant flux source is continuum emission from the solar temperature minimum region. A Kitt Peak magnetogram and spectroheliograph observations at 1600 A taken during a sounding rocket flight of the High Resolution Telescope and Spectrograph from December 11, 1987 were used. The statistical distributions of brightness temperature in the quiet sun at 1600 A, and absolute value of magnetic field strength in the same area were determined from these observations. Using a technique which obtains the best-fit relationship of a given functional form between these two histogram distributions, a quantitative relationship was determined between absolute value of magnetic field strength B and brightness temperature which is essentially linear from 10 to 150 G. An interpretation is suggested, in which a basal heating occurs generally, while brighter elements are produced in magnetic regions with temperature enhancements proportional to B.

  1. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  2. 49 CFR 236.709 - Block, absolute.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Block, absolute. 236.709 Section 236.709 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Block, absolute. A block in which no train is permitted to enter while it is occupied by another train. ...

  3. 49 CFR 236.709 - Block, absolute.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Block, absolute. 236.709 Section 236.709 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Block, absolute. A block in which no train is permitted to enter while it is occupied by another train. ...

  4. Absolute quantification of microbial taxon abundances.

    PubMed

    Props, Ruben; Kerckhof, Frederiek-Maarten; Rubbens, Peter; De Vrieze, Jo; Hernandez Sanabria, Emma; Waegeman, Willem; Monsieurs, Pieter; Hammes, Frederik; Boon, Nico

    2017-02-01

    High-throughput amplicon sequencing has become a well-established approach for microbial community profiling. Correlating shifts in the relative abundances of bacterial taxa with environmental gradients is the goal of many microbiome surveys. As the abundances generated by this technology are semi-quantitative by definition, the observed dynamics may not accurately reflect those of the actual taxon densities. We combined the sequencing approach (16S rRNA gene) with robust single-cell enumeration technologies (flow cytometry) to quantify the absolute taxon abundances. A detailed longitudinal analysis of the absolute abundances resulted in distinct abundance profiles that were less ambiguous and expressed in units that can be directly compared across studies. We further provide evidence that the enrichment of taxa (increase in relative abundance) does not necessarily relate to the outgrowth of taxa (increase in absolute abundance). Our results highlight that both relative and absolute abundances should be considered for a comprehensive biological interpretation of microbiome surveys.

  5. SO_2 Absorption Cross Sections and N_2 VUV Oscillator Strengths for Planetary Atmosphere Studies

    NASA Astrophysics Data System (ADS)

    Smith, Peter L.; Stark, G.; Rufus, J.; Pickering, J. C.; Cox, G.; Huber, K. P.

    1998-09-01

    The determination of the chemical composition of the atmosphere of Io from Hubble Space Telescope observations in the 190-220 nm wavelength region requires knowledge of the photoabsorption cross sections of SO_2 at temperatures ranging from about 110 K to 300 K. We are engaged in a laboratory program to measure SO_2 absorption cross sections with very high resolving power (lambda /delta lambda =~ 450,000) and at a range of temperatures appropriate to the Io atmosphere. Previous photoabsorption measurements, with lambda /delta lambda =~ 100,000, have been unable to resolve the very congested SO_2 spectrum, and, thus, to elucidate the temperature dependence of the cross sections. Our measurements are being performed at Imperial College, London, using an ultraviolet Fourier transform spectrometer. We will present our recently completed room temperature measurements of SO_2 cross sections in the 190-220 nm region and plans for extending these to ~ 195 K. Analyses of Voyager VUV occultation measurements of the N_2-rich atmospheres of Titan and Triton have been hampered by the lack of fundamental spectroscopic data for N_2, in particular, by the lack of reliable f-values and line widths for electronic bands of N_2 in the 80-100 nm wavelength region. We are continuing our program of measurements of band oscillator strengths for the many (approximately 100) N_2 bands between 80 and 100 nm. We report new f-values, derived from data obtained at the Photon Factory (Tsukuba, Japan) synchrotron radiation facility with lambda /delta lambda =~ 130,000, of 37 bands in the 80-86 nm region and 21 bands in the 90-95 nm region. We have also begun the compilation of a searchable archive of N_2 data on the World Wide Web; see http://cfa-www.harvard. edu/amp/data/n2/n2home.html. The archive, covering the spectroscopy of N_2 between 80 and 100 nm, will include published and unpublished (14) N_2, (14) N(15) N, and (15) N_2 line lists and spectroscopic identifications, excited state energy

  6. A lower extremity strength-based profile of NCAA Division I women's basketball and gymnastics athletes: implications for knee joint injury risk assessment.

    PubMed

    Thompson, Brennan J; Cazier, Curtis S; Bressel, Eadric; Dolny, Dennis G

    2018-08-01

    This study aimed to provide a comprehensive strength-based physiological profile of women's NCAA Division I basketball and gymnastic athletes; and to make sport-specific comparisons for various strength characteristics of the knee flexor and extensor muscles. A focus on antagonist muscle balance (hamstrings-to-quadriceps ratios, H:Q) was used to elucidate vulnerabilities in these at-risk female athletes. Fourteen NCAA Division I women's basketball and 13 gymnastics athletes performed strength testing of the knee extensors and flexors. Outcome measures included absolute and relative (body mass normalised) peak torque (PT), rate of torque development at 50, 100, 200 ms (RTD50 etc.) and H:Q ratios of all variables. The basketball athletes had greater absolute strength for all variables except for isokinetic PT at 240°s -1 and isometric RTD50 for the knee extensors. Gymnasts showed ~20% weaker body mass relative concentric PT for the knee flexors at 60 and 120°·s -1 , and decreased conventional H:Q ratios at 60 and 240°·s -1 (~15%). These findings suggest that collegiate level gymnastics athletes may be prone to increased ACL injury risk due to deficient knee flexor strength and H:Q strength imbalance. Coaches may use these findings when implementing injury prevention screening and/or for individualised strength training programming centered around an athletes strength-related deficits.

  7. Absolute Humidity and the Seasonality of Influenza (Invited)

    NASA Astrophysics Data System (ADS)

    Shaman, J. L.; Pitzer, V.; Viboud, C.; Grenfell, B.; Goldstein, E.; Lipsitch, M.

    2010-12-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent re-analysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here we show that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. In addition, we show that variations of the basic and effective reproductive numbers for influenza, caused by seasonal changes in absolute humidity, are consistent with the general timing of pandemic influenza outbreaks observed for 2009 A/H1N1 in temperate regions. Indeed, absolute humidity conditions correctly identify the region of the United States vulnerable to a third, wintertime wave of pandemic influenza. These findings suggest that the timing of pandemic influenza outbreaks is controlled by a combination of absolute humidity conditions, levels of susceptibility and changes in population mixing and contact rates.

  8. Automatic Oscillating Turret.

    DTIC Science & Technology

    1981-03-01

    Final Report: February 1978 ZAUTOMATIC OSCILLATING TURRET SYSTEM September 1980 * 6. PERFORMING 01G. REPORT NUMBER .J7. AUTHOR(S) S. CONTRACT OR GRANT...o....e.... *24 APPENDIX P-4 OSCILLATING BUMPER TURRET ...................... 25 A. DESCRIPTION 1. Turret Controls ...Other criteria requirements were: 1. Turret controls inside cab. 2. Automatic oscillation with fixed elevation to range from 20* below the horizontal to

  9. Tuning the synchronization of a network of weakly coupled self-oscillating gels via capacitors.

    PubMed

    Fang, Yan; Yashin, Victor V; Dickerson, Samuel J; Balazs, Anna C

    2018-05-01

    We consider a network of coupled oscillating units, where each unit comprises a self-oscillating polymer gel undergoing the Belousov-Zhabotinsky (BZ) reaction and an overlaying piezoelectric (PZ) cantilever. Through chemo-mechano-electrical coupling, the oscillations of the networked BZ-PZ units achieve in-phase or anti-phase synchronization, enabling, for example, the storage of information within the system. Herein, we develop numerical and computational models to show that the introduction of capacitors into the BZ-PZ system enhances the dynamical behavior of the oscillating network by yielding additional stable synchronization modes. We specifically show that the capacitors lead to a redistribution of charge in the system and alteration of the force that the PZ cantilevers apply to the underlying gel. Hence, the capacitors modify the strength of the coupling between the oscillators in the network. We utilize a linear stability analysis to determine the phase behavior of BZ-PZ networks encompassing different capacitances, force polarities, and number of units and then verify our findings with numerical simulations. Thus, through analytical calculations and numerical simulations, we determine the impact of the capacitors on the existence of the synchronization modes, their stability, and the rate of synchronization within these complex dynamical systems. The findings from our study can be used to design robotic materials that harness the materials' intrinsic, responsive properties to perform such functions as sensing, actuation, and information storage.

  10. Tuning the synchronization of a network of weakly coupled self-oscillating gels via capacitors

    NASA Astrophysics Data System (ADS)

    Fang, Yan; Yashin, Victor V.; Dickerson, Samuel J.; Balazs, Anna C.

    2018-05-01

    We consider a network of coupled oscillating units, where each unit comprises a self-oscillating polymer gel undergoing the Belousov-Zhabotinsky (BZ) reaction and an overlaying piezoelectric (PZ) cantilever. Through chemo-mechano-electrical coupling, the oscillations of the networked BZ-PZ units achieve in-phase or anti-phase synchronization, enabling, for example, the storage of information within the system. Herein, we develop numerical and computational models to show that the introduction of capacitors into the BZ-PZ system enhances the dynamical behavior of the oscillating network by yielding additional stable synchronization modes. We specifically show that the capacitors lead to a redistribution of charge in the system and alteration of the force that the PZ cantilevers apply to the underlying gel. Hence, the capacitors modify the strength of the coupling between the oscillators in the network. We utilize a linear stability analysis to determine the phase behavior of BZ-PZ networks encompassing different capacitances, force polarities, and number of units and then verify our findings with numerical simulations. Thus, through analytical calculations and numerical simulations, we determine the impact of the capacitors on the existence of the synchronization modes, their stability, and the rate of synchronization within these complex dynamical systems. The findings from our study can be used to design robotic materials that harness the materials' intrinsic, responsive properties to perform such functions as sensing, actuation, and information storage.

  11. Experimental demonstration of revival of oscillations from death in coupled nonlinear oscillators.

    PubMed

    Senthilkumar, D V; Suresh, K; Chandrasekar, V K; Zou, Wei; Dana, Syamal K; Kathamuthu, Thamilmaran; Kurths, Jürgen

    2016-04-01

    We experimentally demonstrate that a processing delay, a finite response time, in the coupling can revoke the stability of the stable steady states, thereby facilitating the revival of oscillations in the same parameter space where the coupled oscillators suffered the quenching of oscillation. This phenomenon of reviving of oscillations is demonstrated using two different prototype electronic circuits. Further, the analytical critical curves corroborate that the spread of the parameter space with stable steady state is diminished continuously by increasing the processing delay. Finally, the death state is completely wiped off above a threshold value by switching the stability of the stable steady state to retrieve sustained oscillations in the same parameter space. The underlying dynamical mechanism responsible for the decrease in the spread of the stable steady states and the eventual reviving of oscillation as a function of the processing delay is explained using analytical results.

  12. Experimental demonstration of revival of oscillations from death in coupled nonlinear oscillators

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

    Senthilkumar, D. V., E-mail: skumarusnld@gmail.com; Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401; Suresh, K.

    We experimentally demonstrate that a processing delay, a finite response time, in the coupling can revoke the stability of the stable steady states, thereby facilitating the revival of oscillations in the same parameter space where the coupled oscillators suffered the quenching of oscillation. This phenomenon of reviving of oscillations is demonstrated using two different prototype electronic circuits. Further, the analytical critical curves corroborate that the spread of the parameter space with stable steady state is diminished continuously by increasing the processing delay. Finally, the death state is completely wiped off above a threshold value by switching the stability of themore » stable steady state to retrieve sustained oscillations in the same parameter space. The underlying dynamical mechanism responsible for the decrease in the spread of the stable steady states and the eventual reviving of oscillation as a function of the processing delay is explained using analytical results.« less

  13. A UNIFIED APPROACH TO THE HELIOSEISMIC INVERSION PROBLEM OF THE SOLAR MERIDIONAL FLOW FROM GLOBAL OSCILLATIONS

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

    Schad, A.; Timmer, J.; Roth, M.

    2011-06-20

    Measurements from tracers and local helioseismology indicate the existence of a meridional flow in the Sun with strength in the order of 15 m s{sup -1} near the solar surface. Different attempts were made to obtain information on the flow profile at depths up to 20 Mm below the solar surface. We propose a method using global helioseismic Doppler measurements with the prospect of inferring the meridional flow profile at greater depths. Our approach is based on the perturbation of the p-mode eigenfunctions of a solar model due to the presence of a flow. The distortion of the oscillation eigenfunctionsmore » is manifested in the mixing of p-modes, which may be measured from global solar oscillation time series. As a new helioseismic measurement quantity, we propose amplitude ratios between oscillations in the Fourier domain. We relate this quantity to the meridional flow and unify the concepts presented here for an inversion procedure to infer the meridional flow from global solar oscillations.« less

  14. Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing

    PubMed Central

    Frederick, Donald E.; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark

    2016-01-01

    stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. PMID:27445151

  15. Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing.

    PubMed

    Frederick, Donald E; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark; Kay, Leslie M

    2016-07-20

    in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. Copyright © 2016 the authors 0270-6474/16/367750-18$15.00/0.

  16. Magnetically coupled magnet-spring oscillators

    NASA Astrophysics Data System (ADS)

    Donoso, G.; Ladera, C. L.; Martín, P.

    2010-05-01

    A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of mechanical, and easily adjustable by the experimenter. The coupling of this new coupled oscillator system is determined by the currents that the magnets induce in two coils connected in series, one to each magnet. It is an interesting case of mechanical oscillators with field-driven coupling, instead of mechanical coupling. Moreover, it is both a coupled and a damped oscillating system that lends itself to a detailed study and presentation of many properties and phenomena of such a system of oscillators. A set of experiments that validates the theoretical model of the oscillators is presented and discussed.

  17. Muscular Strength and Power in 3-to 7-Year-Old Children.

    PubMed

    Fry, Andrew C; Irwin, Carol C; Nicoll, Justin X; Ferebee, David E

    2015-08-01

    To determine absolute and relative (adjusted for body mass) strength, mean power, and mean velocity for upper and lower body resistance exercises, forty-seven young boys and girls participated in maximal strength testing. Healthy young boys and girls, ages 3- to 7-years old, were tested for one-repetition maximum (1-RM) strength, and 70% of 1-RM to determine mean power and mean velocity on the chest press and leg press exercises. Adult weight machines were modified to accommodate the smaller size and lower strength levels of the children. A 2 × 4 (sex × age) ANOVA was used to determine age and sex differences in performance. No interaction or sex differences were observed for any variable at any age. 1-RM strength, mean power, and mean velocity significantly increased across ages (p ≤ .05). When adjusted for body mass, the changes were insignificant, with one exception. Relative mean power for the bench press increased with age. Data indicated children from 3-7 years of age are capable of performing strength and power tests, but may require more attempts at maximal loads compared with adults. It appears that muscular strength and velocity during this stage of development are primarily dependent on increasing body mass, whereas power is influenced by additional variable(s).

  18. Ultrastable Cryogenic Microwave Oscillators

    NASA Astrophysics Data System (ADS)

    Mann, Anthony G.

    Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators have demonstrated a short term frequency stability in the range 10-14 to a few times 10-16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency standards, and as local oscillators in space telemetry ground stations to clean up the transmitter close in phase noise. Fractional frequency stabilities of passive atomic frequency standards are now approaching 3 x10^-14 /τ where τ is the measurement time, limited only by the number of atoms that are being interrogated. This requires an interrogation oscillator whose short-term stability is of the order of 10-14 or better, which cannot be provided by present-day quartz technology. Ultrastable cryogenic microwave oscillators are based on resonators which have very high electrical Q-factors. The resolution of the resonator's linewidth is typically limited by electronics noise to about 1ppm and hence Q-factors in excess of 108 are required. As these are only attained in superconducting cavities or sapphire resonators at low temperatures, use of liquid helium cooling is mandatory, which has so far restricted these oscillators to the research or metrology laboratory. Recently, there has been an effort to dispense with the need for liquid helium and make compact flywheel oscillators for the new generation of primary frequency standards. Work is under way to achieve this goal in space-borne and mobile liquid-nitrogen-cooled systems. The best cryogenic oscillators developed to date are the ``whispering gallery'' (WG) mode sapphire resonator-oscillators of NASA's Jet Propulsion Laboratory (JPL) and the University of Western Australia (UWA), as well as Stanford University's superconducting cavity stabilized oscillator (SCSO). All of these oscillators have demonstrated frequency

  19. Low absolute neutrophil counts in African infants.

    PubMed

    Kourtis, Athena P; Bramson, Brian; van der Horst, Charles; Kazembe, Peter; Ahmed, Yusuf; Chasela, Charles; Hosseinipour, Mina; Knight, Rodney; Lugalia, Lebah; Tegha, Gerald; Joaki, George; Jafali, Robert; Jamieson, Denise J

    2005-07-01

    Infants of African origin have a lower normal range of absolute neutrophil counts than white infants; this fact, however, remains under appreciated by clinical researchers in the United States. During the initial stages of a clinical trial in Malawi, the authors noted an unexpectedly high number of infants with absolute neutrophil counts that would be classifiable as neutropenic using the National Institutes of Health's Division of AIDS toxicity tables. The authors argue that the relevant Division of AIDS table does not take into account the available evidence of low absolute neutrophil counts in African infants and that a systematic collection of data from many African settings might help establish the absolute neutrophil count cutpoints to be used for defining neutropenia in African populations.

  20. Absolute colorimetric characterization of a DSLR camera

    NASA Astrophysics Data System (ADS)

    Guarnera, Giuseppe Claudio; Bianco, Simone; Schettini, Raimondo

    2014-03-01

    A simple but effective technique for absolute colorimetric camera characterization is proposed. It offers a large dynamic range requiring just a single, off-the-shelf target and a commonly available controllable light source for the characterization. The characterization task is broken down in two modules, respectively devoted to absolute luminance estimation and to colorimetric characterization matrix estimation. The characterized camera can be effectively used as a tele-colorimeter, giving an absolute estimation of the XYZ data in cd=m2. The user is only required to vary the f - number of the camera lens or the exposure time t, to better exploit the sensor dynamic range. The estimated absolute tristimulus values closely match the values measured by a professional spectro-radiometer.

  1. OSCILLATION OF NEWLY FORMED LOOPS AFTER MAGNETIC RECONNECTION IN THE SOLAR CHROMOSPHERE

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

    Yang, Shuhong; Xiang, Yongyuan, E-mail: shuhongyang@nao.cas.cn

    With the high spatial and temporal resolution Hα images from the New Vacuum Solar Telescope, we focus on two groups of loops with an X-shaped configuration in the dynamic chromosphere. We find that the anti-directed loops approach each other and reconnect continually. The connectivity of the loops is changed and new loops are formed and stack together. The stacked loops are sharply bent, implying that they are greatly impacted by the magnetic tension force. When another reconnection process takes place, one new loop is formed and stacks with the previously formed ones. Meanwhile, the stacked loops retract suddenly and movemore » toward the balance position, performing an overshoot movement, which led to an oscillation with an average period of about 45 s. The oscillation of newly formed loops after magnetic reconnection in the chromosphere is observed for the first time. We suggest that the stability of the stacked loops is destroyed due to the attachment of the last new loop and then suddenly retract under the effect of magnetic tension. Because of the retraction, another lower loop is pushed outward and performs an oscillation with a period of about 25 s. The different oscillation periods may be due to their difference in three parameters, i.e., loop length, plasma density, and magnetic field strength.« less

  2. Comparing alchemical and physical pathway methods for computing the absolute binding free energy of charged ligands.

    PubMed

    Deng, Nanjie; Cui, Di; Zhang, Bin W; Xia, Junchao; Cruz, Jeffrey; Levy, Ronald

    2018-06-13

    Accurately predicting absolute binding free energies of protein-ligand complexes is important as a fundamental problem in both computational biophysics and pharmaceutical discovery. Calculating binding free energies for charged ligands is generally considered to be challenging because of the strong electrostatic interactions between the ligand and its environment in aqueous solution. In this work, we compare the performance of the potential of mean force (PMF) method and the double decoupling method (DDM) for computing absolute binding free energies for charged ligands. We first clarify an unresolved issue concerning the explicit use of the binding site volume to define the complexed state in DDM together with the use of harmonic restraints. We also provide an alternative derivation for the formula for absolute binding free energy using the PMF approach. We use these formulas to compute the binding free energy of charged ligands at an allosteric site of HIV-1 integrase, which has emerged in recent years as a promising target for developing antiviral therapy. As compared with the experimental results, the absolute binding free energies obtained by using the PMF approach show unsigned errors of 1.5-3.4 kcal mol-1, which are somewhat better than the results from DDM (unsigned errors of 1.6-4.3 kcal mol-1) using the same amount of CPU time. According to the DDM decomposition of the binding free energy, the ligand binding appears to be dominated by nonpolar interactions despite the presence of very large and favorable intermolecular ligand-receptor electrostatic interactions, which are almost completely cancelled out by the equally large free energy cost of desolvation of the charged moiety of the ligands in solution. We discuss the relative strengths of computing absolute binding free energies using the alchemical and physical pathway methods.

  3. Modeling Two-Oscillator Circadian Systems Entrained by Two Environmental Cycles

    PubMed Central

    Oda, Gisele A.; Friesen, W. Otto

    2011-01-01

    Several experimental studies have altered the phase relationship between photic and non-photic environmental, 24 h cycles (zeitgebers) in order to assess their role in the synchronization of circadian rhythms. To assist in the interpretation of the complex activity patterns that emerge from these “conflicting zeitgeber” protocols, we present computer simulations of coupled circadian oscillators forced by two independent zeitgebers. This circadian system configuration was first employed by Pittendrigh and Bruce (1959), to model their studies of the light and temperature entrainment of the eclosion oscillator in Drosophila. Whereas most of the recent experiments have restricted conflicting zeitgeber experiments to two experimental conditions, by comparing circadian oscillator phases under two distinct phase relationships between zeitgebers (usually 0 and 12 h), Pittendrigh and Bruce compared eclosion phase under 12 distinct phase relationships, spanning the 24 h interval. Our simulations using non-linear differential equations replicated complex non-linear phenomena, such as “phase jumps” and sudden switches in zeitgeber preferences, which had previously been difficult to interpret. Our simulations reveal that these phenomena generally arise when inter-oscillator coupling is high in relation to the zeitgeber strength. Manipulations in the structural symmetry of the model indicated that these results can be expected to apply to a wide range of system configurations. Finally, our studies recommend the use of the complete protocol employed by Pittendrigh and Bruce, because different system configurations can generate similar results when a “conflicting zeitgeber experiment” incorporates only two phase relationships between zeitgebers. PMID:21886835

  4. Lifetimes and Oscillator Strengths for Ultraviolet Transitions Involving ns2nd 2D and nsnp2 2D terms in Pb II, Sn II, and Ge II

    NASA Astrophysics Data System (ADS)

    Federman, Steven Robert; Heidarian, Negar; Irving, Richard; Ellis, David; Ritchey, Adam M.; Cheng, Song; Curtis, Larry; Furman, Walter

    2017-06-01

    Radiative transitions of heavy elements are of great importance in astrophysics. Studying the transition rates and their corresponding oscillator strengths allows us to determine abundances of these heavy elements and therefore leads to better understanding of neutron capture processes. We provide the results of our studies on the transitions involving ns2nd 2D and nsnp2 2D terms to the ground term for Pb II, Sn II, and Ge II. These transitions are also of interest due to their strong mixing. Our studies involve experimental measurements performed at the Toledo Heavy Ion Accelerator and theoretical multi-configuration Dirac Hartree-Fock (MCDHF)1 calculations using the development version of the GRASP2K package2. The results are compared with Pb II lines seen in spectra acquired with the Hubble Space Telescope and with other values available in the literature. 1 P. Jönsson et al., The Computational Atomic Structure Group (2014).2 P. Jönsson et al., Comput. Phys. Commun. 184, 2197 (2013).

  5. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

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

    Guo, Yuan-Yuan; Xue, Hai-Bin, E-mail: xuehaibin@tyut.edu.cn; Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024

    2015-05-15

    We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties onmore » the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.« less

  6. Quantum synchronization of a driven self-sustained oscillator.

    PubMed

    Walter, Stefan; Nunnenkamp, Andreas; Bruder, Christoph

    2014-03-07

    Synchronization is a universal phenomenon that is important both in fundamental studies and in technical applications. Here we investigate synchronization in the simplest quantum-mechanical scenario possible, i.e., a quantum-mechanical self-sustained oscillator coupled to an external harmonic drive. Using the power spectrum we analyze synchronization in terms of frequency entrainment and frequency locking in close analogy to the classical case. We show that there is a steplike crossover to a synchronized state as a function of the driving strength. In contrast to the classical case, there is a finite threshold value in driving. Quantum noise reduces the synchronized region and leads to a deviation from strict frequency locking.

  7. Oscillating Permanent Magnets.

    ERIC Educational Resources Information Center

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  8. Oscillation Baselining and Analysis Tool

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

    PNNL developed a new tool for oscillation analysis and baselining. This tool has been developed under a new DOE Grid Modernization Laboratory Consortium (GMLC) Project (GM0072 - “Suite of open-source applications and models for advanced synchrophasor analysis”) and it is based on the open platform for PMU analysis. The Oscillation Baselining and Analysis Tool (OBAT) performs the oscillation analysis and identifies modes of oscillations (frequency, damping, energy, and shape). The tool also does oscillation event baselining (fining correlation between oscillations characteristics and system operating conditions).

  9. Cryogenic, Absolute, High Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

    2001-01-01

    A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

  10. Chemical oscillators in structured media.

    PubMed

    Epstein, Irving R; Vanag, Vladimir K; Balazs, Anna C; Kuksenok, Olga; Dayal, Pratyush; Bhattacharya, Amitabh

    2012-12-18

    Evolution is a characteristic feature of living systems, and many fundamental processes in life, including the cell cycle, take place in a periodic fashion. From a chemistry perspective, these repeating phenomena suggest the question of whether reactions in which concentrations oscillate could provide a basis and/or useful models for the behavior of organisms, and perhaps even their ability to evolve. In this Account, we examine several aspects of the behavior of the prototype oscillating chemical reaction, the Belousov-Zhabotinsky (BZ) system, carried out in microemulsions, arrays of micrometer-sized aqueous droplets suspended in oil, or hydrogels. Each of these environments contains elements of the compartmentalization that likely played a role in the development of the first living cells, and within them we observe behaviors not found in the BZ reaction in simple aqueous solution. Several of these phenomena resemble traits displayed by living organisms. For example, the nanodroplets in a BZ microemulsion "communicate" with each other through a phenomenon analogous to quorum sensing in bacteria to produce a remarkable variety of patterns and waves on length scales 10(5) times the size of a single droplet. A photosensitive version can "remember" an imposed image. Larger, micrometer-sized droplets exhibit similarly rich behavior and allow for the observation and control of individual droplets. These droplets offer promise for building arrays capable of computation by varying the strength and sign of the coupling between drops. Gels that incorporate a BZ catalyst and are immersed in a solution containing the BZ reactants change their shape and volume in oscillations that follow the variation in the redox state of the catalyst. Using this phenomenon, we can construct phototactic gel "worms" or segments of gel that attract one another. Whether such systems will provide more realistic caricatures of life, and whether they can serve as useful materials will largely

  11. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  12. Interplay between resonant tunneling and spin precession oscillations in all-electric all-semiconductor spin transistors

    NASA Astrophysics Data System (ADS)

    Alomar, M. I.; Serra, Llorenç; Sánchez, David

    2016-08-01

    We investigate the transmission properties of a spin transistor coupled to two quantum point contacts acting as a spin injector and detector. In the Fabry-Pérot regime, transport is mediated by quasibound states formed between tunnel barriers. Interestingly, the spin-orbit interaction of the Rashba type can be tuned in such a way that nonuniform spin-orbit fields can point along distinct directions at different points of the sample. We discuss both spin-conserving and spin-flipping transitions as the spin-orbit angle of orientation increases from parallel to antiparallel configurations. Spin precession oscillations are clearly seen as a function of the length of the central channel. Remarkably, we find that these oscillations combine with the Fabry-Pérot motion, giving rise to quasiperiodic transmissions in the purely one-dimensional case. Furthermore, we consider the more realistic case of a finite width in the transverse direction and find that the coherent oscillations become deteriorated for moderate values of the spin-orbit strength. Our results then determine the precise role of the spin-orbit intersubband coupling potential in the Fabry-Pérot-Datta-Das intermixed oscillations.

  13. Relaxation oscillation suppression in continuous-wave intracavity optical parametric oscillators.

    PubMed

    Stothard, David J M; Dunn, Malcolm H

    2010-01-18

    We report a solution to the long standing problem of the occurrence of spontaneous and long-lived bursts of relaxation oscillations which occur when a continuous-wave optical parametric oscillator is operated within the cavity of the parent pump-laser. By placing a second nonlinear crystal within the pump-wave cavity for the purpose of second-harmonic-generation of the pump-wave the additional nonlinear loss thereby arising due to up-conversion effectively suppresses the relaxation oscillations with very little reduction in down-converted power.

  14. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  15. Jasminum sambac flower absolutes from India and China--geographic variations.

    PubMed

    Braun, Norbert A; Sim, Sherina

    2012-05-01

    Seven Jasminum sambac flower absolutes from different locations in the southern Indian state of Tamil Nadu were analyzed using GC and GC-MS. Focus was placed on 41 key ingredients to investigate geographic variations in this species. These seven absolutes were compared with an Indian bud absolute and commercially available J. sambac flower absolutes from India and China. All absolutes showed broad variations for the 10 main ingredients between 8% and 96%. In addition, the odor of Indian and Chinese J. sambac flower absolutes were assessed.

  16. Slow oscillations orchestrating fast oscillations and memory consolidation.

    PubMed

    Mölle, Matthias; Born, Jan

    2011-01-01

    Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical <1Hz electroencephalogram (EEG) slow oscillation and involves the reactivation of newly encoded representations and their subsequent redistribution from temporary hippocampal to neocortical long-term storage sites. Indeed, experimental induction of slow oscillations during non-rapid eye movement (non-REM) sleep by slowly alternating transcranial current stimulation distinctly improves consolidation of declarative memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Advancing Absolute Calibration for JWST and Other Applications

    NASA Astrophysics Data System (ADS)

    Rieke, George; Bohlin, Ralph; Boyajian, Tabetha; Carey, Sean; Casagrande, Luca; Deustua, Susana; Gordon, Karl; Kraemer, Kathleen; Marengo, Massimo; Schlawin, Everett; Su, Kate; Sloan, Greg; Volk, Kevin

    2017-10-01

    We propose to exploit the unique optical stability of the Spitzer telescope, along with that of IRAC, to (1) transfer the accurate absolute calibration obtained with MSX on very bright stars directly to two reference stars within the dynamic range of the JWST imagers (and of other modern instrumentation); (2) establish a second accurate absolute calibration based on the absolutely calibrated spectrum of the sun, transferred onto the astronomical system via alpha Cen A; and (3) provide accurate infrared measurements for the 11 (of 15) highest priority stars with no such data but with accurate interferometrically measured diameters, allowing us to optimize determinations of effective temperatures using the infrared flux method and thus to extend the accurate absolute calibration spectrally. This program is integral to plans for an accurate absolute calibration of JWST and will also provide a valuable Spitzer legacy.

  18. Absolute radiometric calibration of advanced remote sensing systems

    NASA Technical Reports Server (NTRS)

    Slater, P. N.

    1982-01-01

    The distinction between the uses of relative and absolute spectroradiometric calibration of remote sensing systems is discussed. The advantages of detector-based absolute calibration are described, and the categories of relative and absolute system calibrations are listed. The limitations and problems associated with three common methods used for the absolute calibration of remote sensing systems are addressed. Two methods are proposed for the in-flight absolute calibration of advanced multispectral linear array systems. One makes use of a sun-illuminated panel in front of the sensor, the radiance of which is monitored by a spectrally flat pyroelectric radiometer. The other uses a large, uniform, high-radiance reference ground surface. The ground and atmospheric measurements required as input to a radiative transfer program to predict the radiance level at the entrance pupil of the orbital sensor are discussed, and the ground instrumentation is described.

  19. Flexible categorization of relative stimulus strength by the optic tectum

    PubMed Central

    Mysore, Shreesh P.; Knudsen, Eric I.

    2011-01-01

    Categorization is the process by which the brain segregates continuously variable stimuli into discrete groups. We report that patterns of neural population activity in the owl optic tectum (OT) categorize stimuli based on their relative strengths into “strongest” versus “other”. The category boundary shifts adaptively to track changes in the absolute strength of the strongest stimulus. This population-wide categorization is mediated by the responses of a small subset of neurons. Our data constitute the first direct demonstration of an explicit categorization of stimuli by a neural network based on relative stimulus strength or salience. The finding of categorization by the population code relaxes constraints on the properties of downstream decoders that might read out the location of the strongest stimulus. These results indicate that the ensemble neural code in the OT could mediate bottom-up stimulus selection for gaze and attention, a form of stimulus categorization in which the category boundary often shifts within hundreds of milliseconds. PMID:21613487

  20. Emergence of amplitude and oscillation death in identical coupled oscillators.

    PubMed

    Zou, Wei; Senthilkumar, D V; Duan, Jinqiao; Kurths, Jürgen

    2014-09-01

    We deduce rigorous conditions for the onset of amplitude death (AD) and oscillation death (OD) in a system of identical coupled paradigmatic Stuart-Landau oscillators. A nonscalar coupling and high frequency are beneficial for the onset of AD. In strong contrast, scalar diffusive coupling and low intrinsic frequency are in favor of the emergence of OD. Our finding contributes to clearly distinguish intrinsic geneses for AD and OD, and further substantially corroborates that AD and OD are indeed two dynamically distinct oscillation quenching phenomena due to distinctly different mechanisms.

  1. Nonlinear Oscillators in Space Physics

    NASA Technical Reports Server (NTRS)

    Lester,Daniel; Thronson, Harley

    2011-01-01

    We discuss dynamical systems that produce an oscillation without an external time dependent source. Numerical results are presented for nonlinear oscillators in the Em1h's atmosphere, foremost the quasi-biennial oscillation (QBOl. These fluid dynamical oscillators, like the solar dynamo, have in common that one of the variables in a governing equation is strongly nonlinear and that the nonlinearity, to first order, has particular form. of 3rd or odd power. It is shown that this form of nonlinearity can produce the fundamental li'equency of the internal oscillation. which has a period that is favored by the dynamical condition of the fluid. The fundamental frequency maintains the oscillation, with no energy input to the system at that particular frequency. Nonlinearities of 2nd or even power could not maintain the oscillation.

  2. Strength Investigations in Aircraft Construction Under Repeated Application of the Load

    NASA Technical Reports Server (NTRS)

    Gassner, E.

    1946-01-01

    In the calculation of the dimensions of modern machines and building constructions, account is taken of the frequency of the occurrence of the anticipated loads. It is generally assumed that these loads will be repeated an infinite number, or at any rate some millions, of times during the total working life of the construction, When calculating the dimensions of the structural parts of aircraft, on the contrary, a consideration only of those frequencies in the appearance of the loads which actually come into play in the various states of stress is allowable. This is because in aircraft construction it is absolutely essential not only to ensure adequate structural strength but also to keep down the structural weight to the lowest possible limit, Strength tests in which this requirement is directly taken into account have recently been carried out by the DVL Material Strength Department.

  3. Rapid subtropical North Atlantic salinity oscillations across Dansgaard-Oeschger cycles.

    PubMed

    Schmidt, Matthew W; Vautravers, Maryline J; Spero, Howard J

    2006-10-05

    Geochemical and sedimentological evidence suggest that the rapid climate warming oscillations of the last ice age, the Dansgaard-Oeschger cycles, were coupled to fluctuations in North Atlantic meridional overturning circulation through its regulation of poleward heat flux. The balance between cold meltwater from the north and warm, salty subtropical gyre waters from the south influenced the strength and location of North Atlantic overturning circulation during this period of highly variable climate. Here we investigate how rapid reorganizations of the ocean-atmosphere system across these cycles are linked to salinity changes in the subtropical North Atlantic gyre. We combine Mg/Ca palaeothermometry and oxygen isotope ratio measurements on planktonic foraminifera across four Dansgaard-Oeschger cycles (spanning 45.9-59.2 kyr ago) to generate a seawater salinity proxy record from a subtropical gyre deep-sea sediment core. We show that North Atlantic gyre surface salinities oscillated rapidly between saltier stadial conditions and fresher interstadials, covarying with inferred shifts in the Tropical Atlantic hydrologic cycle and North Atlantic overturning circulation. These salinity oscillations suggest a reduction in precipitation into the North Atlantic and/or reduced export of deep salty thermohaline waters during stadials. We hypothesize that increased stadial salinities preconditioned the North Atlantic Ocean for a rapid return to deep overturning circulation and high-latitude warming by contributing to increased North Atlantic surface-water density on interstadial transitions.

  4. Magnetic Resonance Imaging of Solids Using Oscillating Field Gradients

    NASA Astrophysics Data System (ADS)

    Daud, Yaacob Mat

    1992-01-01

    Available from UMI in association with The British Library. A fully automatic solid state NMR imaging spectrometer is described. Use has been made of oscillating field gradients to frequency and phase encode the spatial localisation of the nuclear spins. The RF pulse is applied during the zero crossing of the field gradient, so only low RF power is needed to cover the narrow spectral width of the spins. The oscillating field gradient coils were operated on resonance hence large gradient strength could be applied (up to 200G/cm). Two image reconstruction methods were used, filtered back-projection and two dimensional Fourier transformation. The use of phase encoding, both with oscillating and with pulsed field gradients, enabled us to acquire the data when the gradients were off, and this method proved to be insensitive to eddy currents. It also allowed the use of narrow bandwidth receiver thus improving the signal to noise ratio. The maximum entropy method was used in an effort to remove data truncation effects, although the results were not too convincing. The application of these new imaging schemes, was tested by mapping the T_1 and T_2 of polymers. The calculated relaxation maps produced precise spatial information about T_1 and T_2 which is not possible to achieve by conventional relaxation weight mapping. In a second application, the diffusion of water vapour into dried zeolite powder was studied. We found that the diffusion process is not Fickian.

  5. The Duffin-Kemmer-Petiau oscillator

    NASA Technical Reports Server (NTRS)

    Nedjadi, Youcef; Barrett, Roger

    1995-01-01

    In view of current interest in relativistic spin-one systems and the recent work on the Dirac Oscillator, we introduce the Duffin-Kemmer-Petiau (DKP) equation obtained by using an external potential linear in r. Since, in the non-relativistic limit, the spin 1 representation leads to a harmonic oscillator with a spin-orbit coupling of the Thomas form, we call the equation the DKP oscillator. This oscillator is a relativistic generalization of the quantum harmonic oscillator for scalar and vector bosons. We show that it conserves total angular momentum and that it is exactly solvable. We calculate and discuss the eigenspectrum of the DKP oscillator in the spin 1 representation.

  6. Flow speed has little impact on propulsive characteristics of oscillating foils

    NASA Astrophysics Data System (ADS)

    Van Buren, T.; Floryan, D.; Wei, N.; Smits, A. J.

    2018-01-01

    Experiments are reported on the performance of a pitching and heaving two-dimensional foil in a water channel in either continuous or intermittent motion. We find that the thrust and power are independent of the mean free-stream velocity for twofold changes in the mean velocity (fourfold in the dynamic pressure) and for oscillations in the velocity up to 38% of the mean, where the oscillations are intended to mimic those of freely swimming motions where the thrust varies during the flapping cycle. We demonstrate that the correct velocity scale is not the flow velocity but the mean velocity of the trailing edge. We also find little or no impact of streamwise velocity change on the wake characteristics such as vortex organization, vortex strength, and time-averaged velocity profile development—the wake is both qualitatively and quantitatively unchanged. Our results suggest that constant velocity studies can be used to make robust conclusions about swimming performance without a need to explore the free-swimming condition.

  7. Magnetically Coupled Magnet-Spring Oscillators

    ERIC Educational Resources Information Center

    Donoso, G.; Ladera, C. L.; Martin, P.

    2010-01-01

    A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of…

  8. Bifurcation of synchronous oscillations into torus in a system of two reciprocally inhibitory silicon neurons: experimental observation and modeling.

    PubMed

    Bondarenko, Vladimir E; Cymbalyuk, Gennady S; Patel, Girish; Deweerth, Stephen P; Calabrese, Ronald L

    2004-12-01

    Oscillatory activity in the central nervous system is associated with various functions, like motor control, memory formation, binding, and attention. Quasiperiodic oscillations are rarely discussed in the neurophysiological literature yet they may play a role in the nervous system both during normal function and disease. Here we use a physical system and a model to explore scenarios for how quasiperiodic oscillations might arise in neuronal networks. An oscillatory system of two mutually inhibitory neuronal units is a ubiquitous network module found in nervous systems and is called a half-center oscillator. Previously we created a half-center oscillator of two identical oscillatory silicon (analog Very Large Scale Integration) neurons and developed a mathematical model describing its dynamics. In the mathematical model, we have shown that an in-phase limit cycle becomes unstable through a subcritical torus bifurcation. However, the existence of this torus bifurcation in experimental silicon two-neuron system was not rigorously demonstrated or investigated. Here we demonstrate the torus predicted by the model for the silicon implementation of a half-center oscillator using complex time series analysis, including bifurcation diagrams, mapping techniques, correlation functions, amplitude spectra, and correlation dimensions, and we investigate how the properties of the quasiperiodic oscillations depend on the strengths of coupling between the silicon neurons. The potential advantages and disadvantages of quasiperiodic oscillations (torus) for biological neural systems and artificial neural networks are discussed.

  9. Adhesion Strength Study of EVA Encapsulants on Glass Substrates

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

    Pern, F. J.; Glick, S. H.

    2003-05-01

    An extensive peel-test study was conducted to investigate the various factors that may affect the adhesion strength of photovoltaic module encapsulants, primarily ethylene-vinyl acetate (EVA), on glass substrates of various laminates based on a common configuration of glass/encapsulant/backfoil. The results show that"pure" or"absolute" adhesion strength of EVA-to-glass was very difficult to obtain because of tensile deformation of the soft, semi-elastic EVA layer upon pulling. A mechanically"strong enough" backing foil on the EVA was critical to achieving the"apparent" adhesion strength. Peel test method with a 90-degree-pull yielded similar results to a 180-degree-pull. The 90-degree-pull method better revealed the four stages ofmore » delamination failure of the EVA/backfoil layers. The adhesion strength is affected by a number of factors, which include EVA type, formulation, backfoil type and manufacturing source, glass type, and surface priming treatment on the glass surface or on the backfoil. Effects of the glass-cleaning method and surface texture are not obvious. Direct priming treatments used in the work did not improve, or even worsened, the adhesion. Aging of EVA by storage over~5 years reduced notably the adhesion strength. Lower adhesion strengths were observed for the blank (unformulated) EVA and non-EVA copolymers, such as poly(ethylene-co-methacrylate) (PEMA) or poly(ethylene-co-butylacrylate) (PEBA). Their adhesion strengths increased if the copolymers were cross-linked. Transparent fluoropolymer superstrates such as TefzelTM and DureflexTM films used for thin-film PV modules showed low adhesion strengths to the EVA at a level of~2 N/mm.« less

  10. Coexisting synchronous and asynchronous states in locally coupled array of oscillators by partial self-feedback control

    NASA Astrophysics Data System (ADS)

    Bera, Bidesh K.; Ghosh, Dibakar; Parmananda, Punit; Osipov, G. V.; Dana, Syamal K.

    2017-07-01

    We report the emergence of coexisting synchronous and asynchronous subpopulations of oscillators in one dimensional arrays of identical oscillators by applying a self-feedback control. When a self-feedback is applied to a subpopulation of the array, similar to chimera states, it splits into two/more sub-subpopulations coexisting in coherent and incoherent states for a range of self-feedback strength. By tuning the coupling between the nearest neighbors and the amount of self-feedback in the perturbed subpopulation, the size of the coherent and the incoherent sub-subpopulations in the array can be controlled, although the exact size of them is unpredictable. We present numerical evidence using the Landau-Stuart system and the Kuramoto-Sakaguchi phase model.

  11. Universal, computer facilitated, steady state oscillator, closed loop analysis theory and some applications to precision oscillators

    NASA Technical Reports Server (NTRS)

    Parzen, Benjamin

    1992-01-01

    The theory of oscillator analysis in the immittance domain should be read in conjunction with the additional theory presented here. The combined theory enables the computer simulation of the steady state oscillator. The simulation makes the calculation of the oscillator total steady state performance practical, including noise at all oscillator locations. Some specific precision oscillators are analyzed.

  12. Compton cooling and the signature of Quasi Periodic Oscillations for the transient black hole candidate H 1743-322

    NASA Astrophysics Data System (ADS)

    Mondal, S.; Chakrabarti, S. K.; Debnath, D.; Jana, A.; Molla, A. A.

    In black hole accretion cooling of the Compton cloud has an enormous effect on the dynamics of post-shock flow. We demonstrate that the Compton cooling is highly responsible for the origin of Quasi Periodic Oscillations (QPOs) during the outburst time of the galactic black hole candidates (BHCs). Our study shows that the disk oscillation will take place when infall time from the shock roughly agrees with cooling time in the post-shock region i.e., the resonance condition. We believe that this oscillation is responsible for the origin of QPOs and will occur only when a particular disk condition (disk rate, halo rate and shock strength) satisfies. We also confirm that shock moves with an average velocity of a few meters/sec for the transient BHC H1743-322 due to the presence of Compton cooling.

  13. Linking Comparisons of Absolute Gravimeters: A Proof of Concept for a new Global Absolute Gravity Reference System.

    NASA Astrophysics Data System (ADS)

    Wziontek, H.; Palinkas, V.; Falk, R.; Vaľko, M.

    2016-12-01

    Since decades, absolute gravimeters are compared on a regular basis on an international level, starting at the International Bureau for Weights and Measures (BIPM) in 1981. Usually, these comparisons are based on constant reference values deduced from all accepted measurements acquired during the comparison period. Temporal changes between comparison epochs are usually not considered. Resolution No. 2, adopted by IAG during the IUGG General Assembly in Prague 2015, initiates the establishment of a Global Absolute Gravity Reference System based on key comparisons of absolute gravimeters (AG) under the International Committee for Weights and Measures (CIPM) in order to establish a common level in the microGal range. A stable and unique reference frame can only be achieved, if different AG are taking part in different kind of comparisons. Systematic deviations between the respective comparison reference values can be detected, if the AG can be considered stable over time. The continuous operation of superconducting gravimeters (SG) on selected stations further supports the temporal link of comparison reference values by establishing a reference function over time. By a homogenous reprocessing of different comparison epochs and including AG and SG time series at selected stations, links between several comparisons will be established and temporal comparison reference functions will be derived. By this, comparisons on a regional level can be traced to back to the level of key comparisons, providing a reference for other absolute gravimeters. It will be proved and discussed, how such a concept can be used to support the future absolute gravity reference system.

  14. Synchronization ability of coupled cell-cycle oscillators in changing environments

    PubMed Central

    2012-01-01

    Background The biochemical oscillator that controls periodic events during the Xenopus embryonic cell cycle is centered on the activity of CDKs, and the cell cycle is driven by a protein circuit that is centered on the cyclin-dependent protein kinase CDK1 and the anaphase-promoting complex (APC). Many studies have been conducted to confirm that the interactions in the cell cycle can produce oscillations and predict behaviors such as synchronization, but much less is known about how the various elaborations and collective behavior of the basic oscillators can affect the robustness of the system. Therefore, in this study, we investigate and model a multi-cell system of the Xenopus embryonic cell cycle oscillators that are coupled through a common complex protein, and then analyze their synchronization ability under four different external stimuli, including a constant input signal, a square-wave periodic signal, a sinusoidal signal and a noise signal. Results Through bifurcation analysis and numerical simulations, we obtain synchronization intervals of the sensitive parameters in the individual oscillator and the coupling parameters in the coupled oscillators. Then, we analyze the effects of these parameters on the synchronization period and amplitude, and find interesting phenomena, e.g., there are two synchronization intervals with activation coefficient in the Hill function of the activated CDK1 that activates the Plk1, and different synchronization intervals have distinct influences on the synchronization period and amplitude. To quantify the speediness and robustness of the synchronization, we use two quantities, the synchronization time and the robustness index, to evaluate the synchronization ability. More interestingly, we find that the coupled system has an optimal signal strength that maximizes the synchronization index under different external stimuli. Simulation results also show that the ability and robustness of the synchronization for the square

  15. Reliable binary cell-fate decisions based on oscillations

    NASA Astrophysics Data System (ADS)

    Pfeuty, B.; Kaneko, K.

    2014-02-01

    Biological systems have often to perform binary decisions under highly dynamic and noisy environments, such as during cell-fate determination. These decisions can be implemented by two main bifurcation mechanisms based on the transitions from either monostability or oscillation to bistability. We compare these two mechanisms by using stochastic models with time-varying fields and by establishing asymptotic formulas for the choice probabilities. Different scaling laws for decision sensitivity with respect to noise strength and signal timescale are obtained, supporting a role for oscillatory dynamics in performing noise-robust and temporally tunable binary decision-making. This result provides a rationale for recent experimental evidences showing that oscillatory expression of proteins often precedes binary cell-fate decisions.

  16. Level densities and γ-ray strength functions in Sn isotopes

    NASA Astrophysics Data System (ADS)

    Toft, H. K.; Larsen, A. C.; Agvaanluvsan, U.; Bürger, A.; Guttormsen, M.; Mitchell, G. E.; Nyhus, H. T.; Schiller, A.; Siem, S.; Syed, N. U. H.; Voinov, A.

    2010-06-01

    The nuclear level densities of Sn118,119 and the γ-ray strength functions of Sn116,118,119 below the neutron separation energy are extracted with the Oslo method using the (He3,αγ) and (He3,He3'γ) reactions. The level-density function of Sn119 displays steplike structures. The microcanonical entropies are deduced from the level densities, and the single neutron entropy of Sn119 is determined to be 1.7 ± 0.2 kB. Results from a combinatorial model support the interpretation that some of the low-energy steps in the level density function are caused by neutron pair breaking. An enhancement in all the γ-ray strength functions of Sn116-119, compared to standard models for radiative strength, is observed for the γ-ray energy region of ≃4-11 MeV. These small resonances all have a centroid energy of 8.0(1) MeV and an integrated strength corresponding to 1.7(9)% of the classical Thomas-Reiche-Kuhn sum rule. The Sn resonances may be due to electric dipole neutron skin oscillations or to an enhancement of the giant magnetic dipole resonance.

  17. Neutrino Oscillation Physics

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

    Kayser, Boris

    2012-06-01

    To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures. Neutrinos and photons are by far themore » most abundant elementary particles in the universe. Thus, if we would like to comprehend the universe, we must understand the neutrinos. Of course, studying the neutrinos is challenging, since the only known forces through which these electrically-neutral leptons interact are the weak force and gravity. Consequently, interactions of neutrinos in a detector are very rare events, so that very large detectors and intense neutrino sources are needed to make experiments feasible. Nevertheless, we have confirmed that the weak interactions of neutrinos are correctly described by the Standard Model (SM) of elementary particle physics. Moreover, in the last 14 years, we have discovered that neutrinos have nonzero masses, and that leptons mix. These discoveries have been based on the observation that neutrinos can change from one 'flavor' to another - the phenomenon known as neutrino oscillation. We shall explain the physics of neutrino oscillation, deriving the probability of oscillation in a new way. We shall also provide a very brief guide to references that can be used to study some major neutrino-physics topics other than neutrino oscillation.« less

  18. Virtual Oscillator Controls | Grid Modernization | NREL

    Science.gov Websites

    Virtual Oscillator Controls Virtual Oscillator Controls NREL is developing virtual oscillator Santa-Barbara, and SunPower. Publications Synthesizing Virtual Oscillators To Control Islanded Inverters Synchronization of Parallel Single-Phase Inverters Using Virtual Oscillator Control, IEEE Transactions on Power

  19. Plasma oscillation effects on nested Hall thruster operation and stability

    NASA Astrophysics Data System (ADS)

    McDonald, M. S.; Sekerak, M. J.; Gallimore, A. D.; Hofer, R. R.

    High-power Hall thrusters capable of throughput on the order of 100 kW are currently under development, driven by more demanding mission profiles and rapid growth in on-orbit solar power generation capability. At these power levels the nested Hall thruster (NHT), a new design that concentrically packs multiple thrusters into a single body with a shared magnetic circuit, offers performance and logistical advantages over conventional single-channel Hall thrusters. An important area for risk reduction in NHT development is quantifying inter-channel coupling between discharge channels. This work presents time- and frequency-domain discharge current and voltage measurements paired with high-speed video of the X2, a 10-kW class dual channel NHT. Two “ triads” of operating conditions at 150 V, 3.6 kW and 250 V, 8.6 kW were examined, including each channel in individual operation and both channels in joint operation. For both triads tested, dual-channel operation did not noticeably destabilize the discharge. Partial coupling of outer channel oscillations into the inner channel occurred at 150 V, though oscillation amplitudes did not change greatly. As a percentage of mean discharge current, RMS oscillations at 150 V increased from 8% to 13% on the inner channel and decreased from 10% to 8% on the outer channel from single- to dual-channel operation. At 250 V the RMS/mean level stayed steady at 13% on the inner channel and decreased from 7% to 6% on the outer channel. The only mean discharge parameter noticeably affected was the cathode floating potential, which decreased in magnitude below ground with increased absolute cathode flow rate in dual-channel mode. Rotating spokes were detected on high-speed video across all X2 operating cases with wavelength 12-18 cm, and spoke velocity generally increased from single- to dual-channel operation.

  20. Crystalline sulfur dioxide: Crystal field splittings, absolute band intensities and complex refractive indices derived from infrared spectra

    NASA Technical Reports Server (NTRS)

    Khanna, R. K.; Zhao, Guizhi

    1986-01-01

    The infrared absorption spectra of thin crystalline films of sulfur dioxide at 90 K are reported in the 2700 to 450/cm region. The observed multiplicity of the spectral features in the regions of fundamentals is attributed to factor group splittings of the modes in a biaxial crystal lattice and the naturally present minor S-34, S-36, and O-18 isotopic species. Complex refractive indices determined by an iterative Kramers-Kronig analysis of the extinction data, and absolute band strengths derived from them, are also reported in this region.

  1. The Effects of Magnetic-Field Geometry on Longitudinal Oscillations of Solar Prominences: Cross-Sectional Area Variation for Thin Tubes

    NASA Technical Reports Server (NTRS)

    Luna, M.; Diaz, A. J.; Oliver, R.; Terradas, J.; Karpen, J.

    2016-01-01

    Solar prominences are subject to both field-aligned (longitudinal) and transverse oscillatory motions, as evidenced by an increasing number of observations. Large-amplitude longitudinal motions provide valuable information on the geometry of the filament channel magnetic structure that supports the cool prominence plasma against gravity. Our pendulum model, in which the restoring force is the gravity projected along the dipped field lines of the magnetic structure, best explains these oscillations. However, several factors can influence the longitudinal oscillations, potentially invalidating the pendulum model. Aims. The aim of this work is to study the influence of large-scale variations in the magnetic field strength along the field lines, i.e., variations of the cross-sectional area along the flux tubes supporting prominence threads. Methods. We studied the normal modes of several flux tube configurations, using linear perturbation analysis, to assess the influence of different geometrical parameters on the oscillation properties. Results. We found that the influence of the symmetric and asymmetric expansion factors on longitudinal oscillations is small.Conclusions. We conclude that the longitudinal oscillations are not significantly influenced by variations of the cross-section of the flux tubes, validating the pendulum model in this context.

  2. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  3. Shoulder strength value differences between genders and age groups.

    PubMed

    Balcells-Diaz, Eudald; Daunis-I-Estadella, Pepus

    2018-03-01

    The strength of a normal shoulder differs according to gender and decreases with age. Therefore, the Constant score, which is a shoulder function measurement tool that allocates 25% of the final score to strength, differs from the absolute values but likely reflects a normal shoulder. To compare group results, a normalized Constant score is needed, and the first step to achieving normalization involves statistically establishing the gender differences and age-related decline. In this investigation, we sought to verify the gender difference and age-related decline in strength. We obtained a randomized representative sample of the general population in a small to medium-sized Spanish city. We then invited this population to participate in our study, and we measured their shoulder strength. We performed a statistical analysis with a power of 80% and a P value < .05. We observed a statistically significant difference between the genders and a statistically significant decline with age. To the best of our knowledge, this is the first investigation to study a representative sample of the general population from which conclusions can be drawn regarding Constant score normalization. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  4. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  5. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  6. Stellar laboratories . VIII. New Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths and the Al, Zr, and Xe abundances in the hot white dwarfs G191-B2B and RE 0503-289

    NASA Astrophysics Data System (ADS)

    Rauch, T.; Gamrath, S.; Quinet, P.; Löbling, L.; Hoyer, D.; Werner, K.; Kruk, J. W.; Demleitner, M.

    2017-03-01

    Context. For the spectral analysis of high-resolution and high-signal-to-noise spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. Aims: To search for zirconium and xenon lines in the ultraviolet (UV) spectra of G191-B2B and RE 0503-289, new Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths were calculated. This allows, for the first time, determination of the Zr abundance in white dwarf (WD) stars and improvement of the Xe abundance determinations. Methods: We calculated Zr iv-vii, Xe iv-v, and Xe vii oscillator strengths to consider radiative and collisional bound-bound transitions of Zr and Xe in our NLTE stellar-atmosphere models for the analysis of their lines exhibited in UV observations of the hot WDs G191-B2B and RE 0503-289. Results: We identified one new Zr iv, 14 new Zr v, and ten new Zr vi lines in the spectrum of RE 0503-289. Zr was detected for the first time in a WD. We measured a Zr abundance of -3.5 ± 0.2 (logarithmic mass fraction, approx. 11 500 times solar). We identified five new Xe vi lines and determined a Xe abundance of -3.9 ± 0.2 (approx. 7500 times solar). We determined a preliminary photospheric Al abundance of -4.3 ± 0.2 (solar) in RE 0503-289. In the spectra of G191-B2B, no Zr line was identified. The strongest Zr iv line (1598.948 Å) in our model gave an upper limit of -5.6 ± 0.3 (approx. 100 times solar). No Xe line was identified in the UV spectrum of G191-B2B and we confirmed the previously determined upper limit of -6.8 ± 0.3 (ten times solar). Conclusions: Precise measurements and calculations of atomic data are a prerequisite for advanced NLTE stellar-atmosphere modeling. Observed Zr iv-vi and Xe vi-vii line profiles in the UV spectrum of RE 0503-289 were simultaneously well reproduced with our newly calculated oscillator strengths. Based on observations

  7. Prominence oscillations

    NASA Astrophysics Data System (ADS)

    Arregui, Iñigo; Oliver, Ramón; Ballester, José Luis

    2018-04-01

    Prominences are intriguing, but poorly understood, magnetic structures of the solar corona. The dynamics of solar prominences has been the subject of a large number of studies, and of particular interest is the study of prominence oscillations. Ground- and space-based observations have confirmed the presence of oscillatory motions in prominences and they have been interpreted in terms of magnetohydrodynamic waves. This interpretation opens the door to perform prominence seismology, whose main aim is to determine physical parameters in magnetic and plasma structures (prominences) that are difficult to measure by direct means. Here, we review the observational information gathered about prominence oscillations as well as the theoretical models developed to interpret small and large amplitude oscillations and their temporal and spatial attenuation. Finally, several prominence seismology applications are presented.

  8. OSCILLATING FILAMENTS. I. OSCILLATION AND GEOMETRICAL FRAGMENTATION

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

    Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas, E-mail: gritschm@usm.uni-muenchen.de

    2017-01-10

    We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidalmore » perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.« less

  9. Absolute Frequency Measurements with a Set of Transportable HE-NE/CH4 Optical Frequency Standards and Prospects for Future Design and Applications

    NASA Astrophysics Data System (ADS)

    Gubin, M.; Kovalchuk, E.; Petrukhin, E.; Shelkovnikov, A.; Tyurikov, D.; Gamidov, R.; Erdogan, C.; Sahin, E.; Felder, R.; Gill, P.; Lea, S. N.; Kramer, G.; Lipphardt, B.

    2002-04-01

    The accumulated results of absolute frequency measurements (AFM) carried out in 1997-2000 with transportable double-mode He-Ne/CH4 optical frequency standards (λ = 3 .39μm) in a collaboration of several laboratories are presented. The performance of this secondary optical frequency standard is estimated on the level of 10-13 (in repeatability), and 1 × 10-14/s (in stability). The next steps towards He-Ne/CH4 standards with one order of magnitude better performance, including devices based on monolithic zerodur resonators, are discussed. Important applications of transportable He-Ne/CH4 optical frequency standards have appeared now due to dramatic progress in the field of optical frequency measurements. Used to stabilize the repetition rate of a Ti:Sa fs laser, these compact secondary standards can transfer their performance into the whole optical range covered by a fs comb. Thus they can play the role of a narrow spectrum interrogative oscillator for super-accurate optical or microwave frequency standards substituting in some tasks a H-maser or oscillators based on cryogenic sapphire resonators.

  10. On influences of global and local cues on the rate of synchronization of oscillator networks

    PubMed Central

    Wang, Yongqiang; Doyle, Francis J.

    2011-01-01

    Synchronization of connected oscillator networks under global and local cues is ubiquitous in both science and engineering. Over the last few decades, enormous attention has been paid to study synchronization conditions of connected oscillators in chemistry, physics, mechanics, and particularly in biology. However, the influences of global and local cues on the rate of synchronization have not been fully studied. It is widespread that synchronization is achieved in the simultaneous presence of both global and local cues, such as intercellular coupling signals and external entrainment signals in terms of biological oscillators, and inter-neighbor coupling signals between follower nodes and central guiding signals in terms of groups of mobile autonomous agents. We prove in this paper that strength of the global cue is the only determinant of the rate of synchronization. More specifically, we prove that a stronger global cue means a faster rate of synchronization whereas a stronger local cue does not necessarily make the synchronization rate faster. Our results not only apply to the noise free case, but also apply to the case that the oscillator natural frequencies are subject to white noise. The analysis does not require the interplay to be symmetric or balanced. Simulation results are given to illustrate the proposed results. PMID:21607201

  11. Breakdown Characteristics of SF6 Gap Disturbed by a Metallic Protrusion under Oscillating Transient Overvoltages

    NASA Astrophysics Data System (ADS)

    Kawamura, Tatsuo; Lee, Bok-Hee; Nishimura, Takahiko; Ishii, Masaru

    1994-04-01

    This paper deals with the experimental investigations of particle-initiated breakdown of SF6 gas stressed by the oscillating transient overvoltage and non-oscillating impulse voltages. The experiments are carried out by using hemisphere-to-plane electrodes with a needle-shaped protrusion in the gas pressure range of 0.05 to 0.3 MPa. The temporal growth of the prebreakdown process is measured by a current shunt and a photomultiplier. The electrical breakdown is initiated by the streamer corona in the vicinity of a needle-shaped protrusion and the flashover of test gap is substantially influenced by the local field enhancement due to the space charge formed by the preceding streamer corona. The dependence of the voltage-time characteristics on the polarity of test voltage is appreciable, and the minimum breakdown voltage under the damped oscillating transient overvoltage is approximately the same as that under the standard lightning impulse voltage. In presence of positive polarity, the dielectric strength of SF6 gas stressed by the oscillating transient overvoltage is particularly sensitive to the local field perturbed by a sharp conducting particle. The formative time lag from the first streamer corona to breakdown is longer in negative polarity than in positive polarity and the field stabilization of space charge is more pronounced in negative polarity.

  12. A Conceptual Approach to Absolute Value Equations and Inequalities

    ERIC Educational Resources Information Center

    Ellis, Mark W.; Bryson, Janet L.

    2011-01-01

    The absolute value learning objective in high school mathematics requires students to solve far more complex absolute value equations and inequalities. When absolute value problems become more complex, students often do not have sufficient conceptual understanding to make any sense of what is happening mathematically. The authors suggest that the…

  13. Absolute pitch in a four-year-old boy with autism.

    PubMed

    Brenton, James N; Devries, Seth P; Barton, Christine; Minnich, Heike; Sokol, Deborah K

    2008-08-01

    Absolute pitch is the ability to identify the pitch of an isolated tone. We report on a 4-year-old boy with autism and absolute pitch, one of the youngest reported in the literature. Absolute pitch is thought to be attributable to a single gene, transmitted in an autosomal-dominant fashion. The association of absolute pitch with autism raises the speculation that this talent could be linked to a genetically distinct subset of children with autism. Further, the identification of absolute pitch in even young children with autism may lead to a lifelong skill.

  14. Greater ankle strength, anaerobic and aerobic capacity, and agility predict Ground Combat Military Occupational School graduation in female Marines.

    PubMed

    Allison, Katelyn Fleishman; Keenan, Karen A; Wohleber, Meleesa F; Perlsweig, Katherine A; Pletcher, Erin R; Lovalekar, Mita; Beals, Kim; Coleman, Lawrence C; Nindl, Bradley C

    2017-11-01

    Women can serve in all military occupational specialties (MOS); however, musculoskeletal and physiological characteristics that predict successful completion of ground combat MOS schools by female Marines are unknown. To determine which demographic, musculoskeletal, and physiological characteristics predict graduation from infantry and vehicle ground combat MOS schools in female Marines. Prospective cohort study. Prior to MOS school, the following were assessed in 62 female Marines (22.0±3.0yrs, 163.9±5.8cm, 63.4±7.2kg): isokinetic shoulder, trunk, and knee and isometric ankle strength; body composition; anaerobic power (AP)/capacity (AC); maximal oxygen uptake (VO 2 max); and field-based fitness tests (broad jump, medicine ball throw, pro-agility). Both absolute and normalized (%body mass: %BM) values were utilized for strength, AP, AC, and VO 2 max. Select tests from each Marine's most recent Physical Fitness Test (PFT: abdominal crunches, 3-mile run time) and Combat Fitness Test (CFT: Maneuver Under Fire, Movement to Contact) were recorded. Participants were classified as graduated (N=46) or did not graduate (N=16). Simple logistic regression was performed to determine predictors of MOS school graduation. Statistical significance was set a priori at α=0.05. Absolute and normalized ankle inversion and eversion strength, normalized anaerobic capacity, absolute and normalized VO 2 max, right pro-agility, and PFT 3-mile run time significantly predicted MOS school graduation (p<0.05). Greater ankle strength, better agility, and greater anaerobic and aerobic capacity are important for successful completion of ground combat MOS school in female Marines. Prior to entering ground combat MOS school, it is recommended that female Marines should train to optimize these mobility-centric characteristics. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Rocket Engine Oscillation Diagnostics

    NASA Technical Reports Server (NTRS)

    Nesman, Tom; Turner, James E. (Technical Monitor)

    2002-01-01

    Rocket engine oscillating data can reveal many physical phenomena ranging from unsteady flow and acoustics to rotordynamics and structural dynamics. Because of this, engine diagnostics based on oscillation data should employ both signal analysis and physical modeling. This paper describes an approach to rocket engine oscillation diagnostics, types of problems encountered, and example problems solved. Determination of design guidelines and environments (or loads) from oscillating phenomena is required during initial stages of rocket engine design, while the additional tasks of health monitoring, incipient failure detection, and anomaly diagnostics occur during engine development and operation. Oscillations in rocket engines are typically related to flow driven acoustics, flow excited structures, or rotational forces. Additional sources of oscillatory energy are combustion and cavitation. Included in the example problems is a sampling of signal analysis tools employed in diagnostics. The rocket engine hardware includes combustion devices, valves, turbopumps, and ducts. Simple models of an oscillating fluid system or structure can be constructed to estimate pertinent dynamic parameters governing the unsteady behavior of engine systems or components. In the example problems it is shown that simple physical modeling when combined with signal analysis can be successfully employed to diagnose complex rocket engine oscillatory phenomena.

  16. Self-Synchronized Phenomena Generated in Rotor-Type Oscillators: On the Influence of Coupling Condition between Oscillators

    NASA Astrophysics Data System (ADS)

    Bonkobara, Yasuhiro; Mori, Hiroki; Kondou, Takahiro; Ayabe, Takashi

    Self-synchronized phenomena generated in rotor-type oscillators mounted on a straight-line spring-mass system are investigated experimentally and analytically. In the present study, we examine the occurrence region and pattern of self-synchronization in two types of coupled oscillators: rigidly coupled oscillators and elastically coupled oscillators. It is clarified that the existence regions of stable solutions are governed mainly by the linear natural frequency of each spring-mass system. The results of numerical analysis confirm that the self-synchronized solutions of the elastically coupled oscillators correspond to those of the rigidly coupled oscillators. In addition, the results obtained in the present study are compared with the previously reported results for a metronome system and a moving apparatus and the different properties of the phenomena generated in the rotor-type oscillators and the pendulum-type oscillators are shown in terms of the construction of branches of self-synchronized solution and the stability.

  17. Ionization oscillations in Hall accelerators

    NASA Astrophysics Data System (ADS)

    Barral, S.; Peradzyński, Z.

    2010-01-01

    The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.

  18. Effect of gravity on human spontaneous 10-Hz electroencephalographic oscillations during the arrest reaction.

    PubMed

    Cheron, G; Leroy, A; De Saedeleer, C; Bengoetxea, A; Lipshits, M; Cebolla, A; Servais, L; Dan, B; Berthoz, A; McIntyre, J

    2006-11-22

    Electroencephalographic oscillations at 10 Hz (alpha and mu rhythms) are the most prominent rhythms observed in awake, relaxed (eye-closed) subjects. These oscillations may be considered as a marker of cortical inactivity or an index of the active inhibition of the sensory information. Different cortical sources may participate in the 10-Hz oscillation and appear to be modulated by the sensory context and functional demands. In microgravity, the marked reduction in multimodal graviceptive inputs to cortical networks participating in the representation of space could be expected to affect the 10-Hz activity. The effect of microgravity on this basic oscillation has heretofore not been studied quantitatively. Because the alpha rhythm has a functional role in the regulation of network properties of the visual areas, we hypothesised that the absence of gravity would affect its strength. Here, we report the results of an experiment conducted over the course of 3 space flights, in which we quantified the power of the 10-Hz activity in relation to the arrest reaction (i.e., in 2 distinct physiological states: eyes open and eyes closed). We observed that the power of the spontaneous 10-Hz oscillation recorded in the eyes-closed state in the parieto-occipital (alpha rhythm) and sensorimotor areas (mu rhythm) increased in the absence of gravity. The suppression coefficient during the arrest reaction and the related spectral perturbations produced by eye-opening/closure state transition also increased in on orbit. These results are discussed in terms of current theories on the source and the importance of the alpha rhythm for cognitive function.

  19. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  20. The absolute disparity anomaly and the mechanism of relative disparities.

    PubMed

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-06-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1).

  1. The absolute disparity anomaly and the mechanism of relative disparities

    PubMed Central

    Chopin, Adrien; Levi, Dennis; Knill, David; Bavelier, Daphne

    2016-01-01

    There has been a long-standing debate about the mechanisms underlying the perception of stereoscopic depth and the computation of the relative disparities that it relies on. Relative disparities between visual objects could be computed in two ways: (a) using the difference in the object's absolute disparities (Hypothesis 1) or (b) using relative disparities based on the differences in the monocular separations between objects (Hypothesis 2). To differentiate between these hypotheses, we measured stereoscopic discrimination thresholds for lines with different absolute and relative disparities. Participants were asked to judge the depth of two lines presented at the same distance from the fixation plane (absolute disparity) or the depth between two lines presented at different distances (relative disparity). We used a single stimulus method involving a unique memory component for both conditions, and no extraneous references were available. We also measured vergence noise using Nonius lines. Stereo thresholds were substantially worse for absolute disparities than for relative disparities, and the difference could not be explained by vergence noise. We attribute this difference to an absence of conscious readout of absolute disparities, termed the absolute disparity anomaly. We further show that the pattern of correlations between vergence noise and absolute and relative disparity acuities can be explained jointly by the existence of the absolute disparity anomaly and by the assumption that relative disparity information is computed from absolute disparities (Hypothesis 1). PMID:27248566

  2. Long-term oscillations of sunspots and a special class of artifacts in SOHO/MDI and SDO/HMI data

    NASA Astrophysics Data System (ADS)

    Efremov, V. I.; Solov'ev, A. A.; Parfinenko, L. D.; Riehokainen, A.; Kirichek, E.; Smirnova, V. V.; Varun, Y. N.; Bakunina, I.; Zhivanovich, I.

    2018-03-01

    A specific type of artifacts (named as " p2p"), that originate due to displacement of the image of a moving object along the digital (pixel) matrix of receiver are analyzed in detail. The criteria of appearance and the influence of these artifacts on the study of long-term oscillations of sunspots are deduced. The obtained criteria suggest us methods for reduction or even elimination of these artifacts. It is shown that the use of integral parameters can be very effective against the " p2p" artifact distortions. The simultaneous observations of sunspot magnetic field and ultraviolet intensity of the umbra have given the same periods for the long-term oscillations. In this way the real physical nature of the oscillatory process, which is independent of the artifacts have been confirmed again. A number of examples considered here confirm the dependence between the periods of main mode of the sunspot magnetic field long-term oscillations and its strength. The dependence was derived earlier from both the observations and the theoretical model of the shallow sunspot. The anti-phase behavior of time variations of sunspot umbra area and magnetic field of the sunspot demonstrates that the umbra of sunspot moves in long-term oscillations as a whole: all its points oscillate with the same phase.

  3. Modeling the quasi-biennial oscillation's effect on the winter stratospheric circulation

    NASA Technical Reports Server (NTRS)

    O'Sullivan, Donal; Young, Richard E.

    1992-01-01

    The influence of the equatorial quasi-biennial oscillation (QBO) on the winter middle atmosphere is modeled with a mechanistic global primitive equation model. The model's polar vortex evolution is sensitive to the lower stratosphere's tropical winds, with the polar vortex becoming more (less) disturbed as the lower stratospheric winds are more easterly (westerly). This agrees with the observed relationship between wintertime polar circulation strength and the phase of the QBO in the lower stratosphere. In these experiments it is the extratropical planetary Rossby waves that provide the tropical-extratropical coupling mechanism. More easterly tropical winds in the lower stratosphere act to confine the extratropical Rossby waves farther north and closer to the vortex at the QBO altitudes, weakening the vortex relative to the case of westerly QBO phase. While the QBO winds occur in the lower stratosphere, the anomaly in the polar vortex strength is strongest at higher levels.

  4. Brain Oscillations, Hypnosis, and Hypnotizability.

    PubMed

    Jensen, Mark P; Adachi, Tomonori; Hakimian, Shahin

    2015-01-01

    This article summarizes the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. The authors propose that this role may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis, specifically, that the increases in theta oscillations and changes in gamma activity observed with hypnosis may underlie some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis and for enhancing response to hypnotic treatments.

  5. Rotation-excited perfect oscillation of a tri-walled nanotube-based oscillator at ultralow temperature

    NASA Astrophysics Data System (ADS)

    Cai, Kun; Zhang, Xiaoni; Shi, Jiao; Qin, Qing H.

    2017-04-01

    In recent years, carbon-nanotube (CNT)-based gigahertz oscillators have been widely used in numerous areas of practical engineering such as high-speed digital, analog circuits, and memory cells. One of the major challenges to practical applications of the gigahertz oscillator is generating a stable oscillation process from the gigahertz oscillators and then maintaining the stable process for a specified period of time. To address this challenge, an oscillator from a triple-walled CNT-based rotary system is proposed and analyzed numerically in this paper, using a molecular dynamics approach. In this system, the outer tube is fixed partly as a stator. The middle tube, with a constant rotation, is named Rotor 2 and runs in the stator. The inner tube acts as Rotor 1, which can rotate freely in Rotor 2. Due to the friction between the two rotors when they have relative motion, the rotational frequency of Rotor 1 increases continuously and tends to converge with that of Rotor 2. During rotation, the oscillation of Rotor 1 may be excited owing to both a strong end barrier at Rotor 2 and thermal vibration of atoms in the tubes. From the discussion on the effects of length of Rotor 1, temperature, and input rotational frequency of Rotor 2 on the dynamic response of Rotor 1, an effective way to control the oscillation of Rotor 1 is found. Being much longer than Rotor 2, Rotor 1 will have perfect oscillation, i.e., with both stable (or nearly constant) period and amplitude—especially at relatively low temperature. This discovery can be taken as a useful guidance for the design of an oscillator from CNTs.

  6. Rotation-excited perfect oscillation of a tri-walled nanotube-based oscillator at ultralow temperature.

    PubMed

    Cai, Kun; Zhang, Xiaoni; Shi, Jiao; Qin, Qing H

    2017-04-18

    In recent years, carbon-nanotube (CNT)-based gigahertz oscillators have been widely used in numerous areas of practical engineering such as high-speed digital, analog circuits, and memory cells. One of the major challenges to practical applications of the gigahertz oscillator is generating a stable oscillation process from the gigahertz oscillators and then maintaining the stable process for a specified period of time. To address this challenge, an oscillator from a triple-walled CNT-based rotary system is proposed and analyzed numerically in this paper, using a molecular dynamics approach. In this system, the outer tube is fixed partly as a stator. The middle tube, with a constant rotation, is named Rotor 2 and runs in the stator. The inner tube acts as Rotor 1, which can rotate freely in Rotor 2. Due to the friction between the two rotors when they have relative motion, the rotational frequency of Rotor 1 increases continuously and tends to converge with that of Rotor 2. During rotation, the oscillation of Rotor 1 may be excited owing to both a strong end barrier at Rotor 2 and thermal vibration of atoms in the tubes. From the discussion on the effects of length of Rotor 1, temperature, and input rotational frequency of Rotor 2 on the dynamic response of Rotor 1, an effective way to control the oscillation of Rotor 1 is found. Being much longer than Rotor 2, Rotor 1 will have perfect oscillation, i.e., with both stable (or nearly constant) period and amplitude-especially at relatively low temperature. This discovery can be taken as a useful guidance for the design of an oscillator from CNTs.

  7. Polynomial law for controlling the generation of n-scroll chaotic attractors in an optoelectronic delayed oscillator

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

    Márquez, Bicky A., E-mail: bmarquez@ivic.gob.ve; Suárez-Vargas, José J., E-mail: jjsuarez@ivic.gob.ve; Ramírez, Javier A.

    2014-09-01

    Controlled transitions between a hierarchy of n-scroll attractors are investigated in a nonlinear optoelectronic oscillator. Using the system's feedback strength as a control parameter, it is shown experimentally the transition from Van der Pol-like attractors to 6-scroll, but in general, this scheme can produce an arbitrary number of scrolls. The complexity of every state is characterized by Lyapunov exponents and autocorrelation coefficients.

  8. Direct observation of surface-state thermal oscillations in SmB6 oscillators

    NASA Astrophysics Data System (ADS)

    Casas, Brian; Stern, Alex; Efimkin, Dmitry K.; Fisk, Zachary; Xia, Jing

    2018-01-01

    SmB6 is a mixed valence Kondo insulator that exhibits a sharp increase in resistance following an activated behavior that levels off and saturates below 4 K. This behavior can be explained by the proposal of SmB6 representing a new state of matter, a topological Kondo insulator, in which a Kondo gap is developed, and topologically protected surface conduction dominates low-temperature transport. Exploiting its nonlinear dynamics, a tunable SmB6 oscillator device was recently demonstrated, where a small dc current generates large oscillating voltages at frequencies from a few Hz to hundreds of MHz. This behavior was explained by a theoretical model describing the thermal and electronic dynamics of coupled surface and bulk states. However, a crucial aspect of this model, the predicted temperature oscillation in the surface state, has not been experimentally observed to date. This is largely due to the technical difficulty of detecting an oscillating temperature of the very thin surface state. Here we report direct measurements of the time-dependent surface-state temperature in SmB6 with a RuO2 microthermometer. Our results agree quantitatively with the theoretically simulated temperature waveform, and hence support the validity of the oscillator model, which will provide accurate theoretical guidance for developing future SmB6 oscillators at higher frequencies.

  9. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  10. Monolithically integrated absolute frequency comb laser system

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

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  11. Analysis on Patterns of Globally Coupled Phase Oscillators with Attractive and Repulsive Interactions

    NASA Astrophysics Data System (ADS)

    Wang, Peng-Fei; Ruan, Xiao-Dong; Xu, Zhong-Bin; Fu, Xin

    2015-11-01

    The Hong-Strogatz (HS) model of globally coupled phase oscillators with attractive and repulsive interactions reflects the fact that each individual (oscillator) has its own attitude (attractive or repulsive) to the same environment (mean field). Previous studies on HS model focused mainly on the stable states on Ott-Antonsen (OA) manifold. In this paper, the eigenvalues of the Jacobi matrix of each fixed point in HS model are explicitly derived, with the aim to understand the local dynamics around each fixed point. Phase transitions are described according to relative population and coupling strength. Besides, the dynamics off OA manifold is studied. Supported by the National Basic Research Program of China under Grant No. 2015CB057301, the Applied Research Project of Public Welfare Technology of Zhejiang Province under Grant No. 201SC31109 and China Postdoctoral Science Foundation under Grant No. 2014M560483

  12. Mass transfer from an oscillating microsphere.

    PubMed

    Zhu, Jiahua; Zheng, Feng; Laucks, Mary L; Davis, E James

    2002-05-15

    The enhancement of mass transfer from single oscillating aerocolloidal droplets having initial diameters approximately 40 microm has been measured using electrodynamic levitation to trap and oscillate a droplet evaporating in nitrogen gas. The frequency and amplitude of the oscillation were controlled by means of ac and dc fields applied to the ring electrodes of the electrodynamic balance (EDB). Elastic light scattering was used to size the droplet. It is shown that the mass transfer process for a colloidal or aerocolloidal particle oscillating in the Stokes flow regime is governed by a Peclet number for oscillation and a dimensionless oscillation parameter that represents the ratio of the diffusion time scale to the oscillation time scale. Evaporation rates are reported for stably oscillating droplets that are as much as five times the rate for evaporation in a stagnant gas. The enhancement is substantially larger than that predicted by quasi-steady-flow mass transfer.

  13. Abstract Spatial Reasoning as an Autistic Strength

    PubMed Central

    Stevenson, Jennifer L.; Gernsbacher, Morton Ann

    2013-01-01

    Autistic individuals typically excel on spatial tests that measure abstract reasoning, such as the Block Design subtest on intelligence test batteries and the Raven’s Progressive Matrices nonverbal test of intelligence. Such well-replicated findings suggest that abstract spatial processing is a relative and perhaps absolute strength of autistic individuals. However, previous studies have not systematically varied reasoning level – concrete vs. abstract – and test domain – spatial vs. numerical vs. verbal, which the current study did. Autistic participants (N = 72) and non-autistic participants (N = 72) completed a battery of 12 tests that varied by reasoning level (concrete vs. abstract) and domain (spatial vs. numerical vs. verbal). Autistic participants outperformed non-autistic participants on abstract spatial tests. Non-autistic participants did not outperform autistic participants on any of the three domains (spatial, numerical, and verbal) or at either of the two reasoning levels (concrete and abstract), suggesting similarity in abilities between autistic and non-autistic individuals, with abstract spatial reasoning as an autistic strength. PMID:23533615

  14. Effects of Partner's Improvisational Resistance Training on dancers' muscular strength.

    PubMed

    Vetter, Rheba E; Dorgo, Sandor

    2009-05-01

    The purpose of this study was to observe the effects of Partner's Improvisational Resistance Training (PIRT) on muscular strength, body circumference, and body fat percentage in 10 female college-age dancers in comparison with 8 female dancers in a control group. The PIRT program, based on the concepts of manual resistance training, is the application of contact improvisation in a systematic strength development program, which proposes a way of contextualizing muscular strength development within the dance class. The program lasted 8 weeks, meeting 3 times weekly for 60-minute sessions. The muscular strength pre- and posttests included 1-repetition maximum (1RM) for leg extension, leg flexion, leg press, bench press, lat pulldown, back extension, and modified sit-up. Hydrostatic weighing for body composition and circumference measures on the waist, hip, shoulder, upper arm, and thigh were made pre- and posttest analyses. There were no significant pretest differences between the groups for age, height, body weight, body fat percentage, any of the circumference measures, or 5 of the 7 muscular strength measures. At posttest, neither group showed significant changes in total body weight, body fat percentage, or lean body weight. The experimental group showed significant decrements in the waist and hip circumference measures, and all other body circumference changes were nonsignificant. The experimental group showed significant changes from pretest to posttest for all seven 1RM strength measures and greater absolute and relative strength improvements in 5 measures compared with the control group. Thus, the 8-week PIRT program for female dancers was found effective in improving overall muscular strength and decreasing circumference in the waist-hip region, but it did not elicit significant changes in body composition.

  15. The Question of Spontaneous Wing Oscillations : Determination of Critical Velocity Through Flight-oscillation Tests

    NASA Technical Reports Server (NTRS)

    Schlippe, B V

    1936-01-01

    Determination of the spontaneous oscillations of a wing or tail unit entail many difficulties, both the mathematical determination and the determination by static wing oscillation tests being far from successful and flight tests involving very great risks. The present paper gives a method developed at the Junkers Airplane Company by which the critical velocity with respect to spontaneous oscillations of increasing amplitude can be ascertained in flight tests without undue risks, the oscillation of the surface being obtained in the tests by the application of an external force.

  16. Persistent lung oscillator response to CO2 after buccal oscillator inhibition in the adult frog.

    PubMed

    Leclère, Renaud; Straus, Christian; Similowski, Thomas; Bodineau, Laurence; Fiamma, Marie-Noëlle

    2012-08-15

    The automatic ventilatory drive in amphibians depends on two oscillators interacting with each other, the gill/buccal and lung oscillators. The lung oscillator would be homologous to the mammalian pre-Bötzinger complex and the gill/buccal oscillator homologous to the mammalian parafacial respiratory group/retrotrapezoid nucleus (pFRG/RTN). Dysfunction of the pFRG/RTN has been involved in the development of respiratory diseases associated to the loss of CO(2) chemosensitivity such as the congenital central hypoventilation syndrome. Here, on adult in vitro isolated frog brainstem, consequences of the buccal oscillator inhibition (by reducing Cl(-)) were evaluated on the respiratory rhythm developed by the lung oscillator under hypercapnic challenges. Our results show that under low Cl(-) concentration (i) the buccal oscillator is strongly inhibited and the lung burst frequency and amplitude decreased and (ii) it persists a powerful CO(2) chemosensitivity. In conclusion, in frog, the CO(2) chemosensitivity depends on cellular contingent(s) whose the functioning is independent of the concentration of Cl(-) and origin remains unknown. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the

  18. Large deformation of self-oscillating polymer gel

    NASA Astrophysics Data System (ADS)

    Maeda, Shingo; Kato, Terukazu; Otsuka, Yuji; Hosoya, Naoki; Cianchetti, Matteo; Laschi, Cecilia

    2016-01-01

    A self-oscillating gel is a system that generates an autonomous volume oscillation. This oscillation is powered by the chemical energy of the Belousov-Zhabotinsky (BZ) reaction, which demonstrates metal ion redox oscillation. A self-oscillating gel is composed of Poly-N -isopropylacrylamide (PNIPAAm) with a metal ion. In this study, we found that the displacement of the volume oscillation in a self-oscillating gel could be controlled by its being subjected to a prestraining process. We also revealed the driving mechanism of the self-oscillating gel from the point of view of thermodynamics. We observed that the polymer-solvent interaction parameter χ is altered by the redox changes to the metal ion incorporated in the self-oscillating gel. The prestraining process leads to changes in χ and changes in enthalpy and entropy when the self-oscillating gel is in a reduced and oxidized state. We found that nonprestrained gel samples oscillate in a poor solution (χ >0.5 ) and prestrained gel samples oscillate in a good solution (χ <0.5 ).

  19. Brain Oscillations, Hypnosis, and Hypnotizability

    PubMed Central

    Jensen, Mark P.; Adachi, Tomonori; Hakimian, Shahin

    2014-01-01

    In this article, we summarize the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, and are usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. Here we propose that it is this role that may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis; specifically that theta oscillations may facilitate, and that changes in gamma activity observed with hypnosis may underlie, some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis, and for enhancing response to hypnotic treatments. PMID:25792761

  20. Absolute Quantification of Human Liver Phosphorus-Containing Metabolites In Vivo Using an Inhomogeneous Spoiling Magnetic Field Gradient

    PubMed Central

    Bashir, Adil; Gropler, Robert; Ackerman, Joseph

    2015-01-01

    Purpose Absolute concentrations of high-energy phosphorus (31P) metabolites in liver provide more important insight into physiologic status of liver disease compared to resonance integral ratios. A simple method for measuring absolute concentrations of 31P metabolites in human liver is described. The approach uses surface spoiling inhomogeneous magnetic field gradient to select signal from liver tissue. The technique avoids issues caused by respiratory motion, chemical shift dispersion associated with linear magnetic field gradients, and increased tissue heat deposition due to radiofrequency absorption, especially at high field strength. Methods A method to localize signal from liver was demonstrated using superficial and highly non-uniform magnetic field gradients, which eliminate signal(s) from surface tissue(s) located between the liver and RF coil. A double standard method was implemented to determine absolute 31P metabolite concentrations in vivo. 8 healthy individuals were examined in a 3 T MR scanner. Results Concentrations of metabolites measured in eight healthy individuals are: γ-adenosine triphosphate (ATP) = 2.44 ± 0.21 (mean ± sd) mmol/l of wet tissue volume, α-ATP = 3.2 ± 0.63 mmol/l, β-ATP = 2.98 ± 0.45 mmol/l, inorganic phosphates (Pi) = 1.87 ± 0.25 mmol/l, phosphodiesters (PDE) = 10.62 ± 2.20 mmol/l and phosphomonoesters (PME) = 2.12 ± 0.51 mmol/l. All are in good agreement with literature values. Conclusions The technique offers robust and fast means to localize signal from liver tissue, allows absolute metabolite concentration determination, and avoids problems associated with constant field gradient (linear field variation) localization methods. PMID:26633549

  1. Opto-electronic oscillator and its applications

    NASA Astrophysics Data System (ADS)

    Yao, X. S.; Maleki, Lute

    1997-04-01

    We review the properties of a new class of microwave oscillators called opto-electronic oscillators (OEO). We present theoretical and experimental results of a multi-loop technique for single mode selection. We then describe a new development called coupled OEO (COEO) in which the electrical oscillation is directly coupled with the optical oscillation, producing an OEO that generates stable optical pulses and single mode microwave oscillation simultaneously. Finally we discuss various applications of OEO.

  2. Lower extremity muscle size and strength and aerobic capacity decrease with caloric restriction but not with exercise-induced weight loss

    PubMed Central

    Weiss, Edward P.; Racette, Susan B.; Villareal, Dennis T.; Fontana, Luigi; Steger-May, Karen; Schechtman, Kenneth B.; Klein, Samuel; Ehsani, Ali A.; Holloszy, John O.

    2015-01-01

    Caloric restriction (CR) results in fat loss; however, it may also result in loss of muscle and thereby reduce strength and aerobic capacity (V̇O2 max). These effects may not occur with exercise-induced weight loss (EX) because of the anabolic effects of exercise on heart and skeletal muscle. We tested the hypothesis that CR reduces muscle size and strength and V̇O2 max, whereas EX preserves or improves these parameters. Healthy 50- to 60-yr-old men and women (body mass index of 23.5–29.9 kg/m2) were studied before and after 12 mo of weight loss by CR (n = 18) or EX (n = 16). Lean mass was assessed by dual-energy X-ray absorptiometry, thigh muscle volume by MRI, isometric and isokinetic knee flexor strength by dynamometry, and treadmill V̇O2 max by indirect calorimetry. Both interventions caused significant decreases in body weight (CR: −10.7 ± 1.4%, EX: −9.5 ± 1.5%) and lean mass (CR: −3.5 ± 0.7%, EX: −2.2 ± 0.8%), with no significant differences between groups. Significant decreases in thigh muscle volume (−6.9 ± 0.8%) and composite knee flexion strength (−7.2 ± 3%) occurred in the CR group only. Absolute V̇O2 max decreased significantly in the CR group (−6.8 ± 2.3%), whereas the EX group had significant increases in both absolute (+15.5 ± 2.4%) and relative (+28.3 ± 3.0%) V̇O2 max. These data provide evidence that muscle mass and absolute physical work capacity decrease in response to 12 mo of CR but not in response to a similar weight loss induced by exercise. These findings suggest that, during EX, the body adapts to maintain or even enhance physical performance capacity. PMID:17095635

  3. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  4. State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

    NASA Astrophysics Data System (ADS)

    Ward, Daniel R.; Kim, Dohun; Savage, Donald E.; Lagally, Max G.; Foote, Ryan H.; Friesen, Mark; Coppersmith, Susan N.; Eriksson, Mark A.

    2016-10-01

    Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of double quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. We further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau-Zener-Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.

  5. State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

    DOE PAGES

    Ward, Daniel R.; Kim, Dohun; Savage, Donald E.; ...

    2016-10-18

    Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of doublemore » quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. Finally, we further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau–Zener–Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.« less

  6. State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

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

    Ward, Daniel R.; Kim, Dohun; Savage, Donald E.

    Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of doublemore » quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. Finally, we further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau–Zener–Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.« less

  7. Hidden Attractors in Dynamical Systems. From Hidden Oscillations in Hilbert-Kolmogorov Aizerman, and Kalman Problems to Hidden Chaotic Attractor in Chua Circuits

    NASA Astrophysics Data System (ADS)

    Leonov, G. A.; Kuznetsov, N. V.

    From a computational point of view, in nonlinear dynamical systems, attractors can be regarded as self-excited and hidden attractors. Self-excited attractors can be localized numerically by a standard computational procedure, in which after a transient process a trajectory, starting from a point of unstable manifold in a neighborhood of equilibrium, reaches a state of oscillation, therefore one can easily identify it. In contrast, for a hidden attractor, a basin of attraction does not intersect with small neighborhoods of equilibria. While classical attractors are self-excited, attractors can therefore be obtained numerically by the standard computational procedure. For localization of hidden attractors it is necessary to develop special procedures, since there are no similar transient processes leading to such attractors. At first, the problem of investigating hidden oscillations arose in the second part of Hilbert's 16th problem (1900). The first nontrivial results were obtained in Bautin's works, which were devoted to constructing nested limit cycles in quadratic systems, that showed the necessity of studying hidden oscillations for solving this problem. Later, the problem of analyzing hidden oscillations arose from engineering problems in automatic control. In the 50-60s of the last century, the investigations of widely known Markus-Yamabe's, Aizerman's, and Kalman's conjectures on absolute stability have led to the finding of hidden oscillations in automatic control systems with a unique stable stationary point. In 1961, Gubar revealed a gap in Kapranov's work on phase locked-loops (PLL) and showed the possibility of the existence of hidden oscillations in PLL. At the end of the last century, the difficulties in analyzing hidden oscillations arose in simulations of drilling systems and aircraft's control systems (anti-windup) which caused crashes. Further investigations on hidden oscillations were greatly encouraged by the present authors' discovery, in 2010

  8. High Resolution UV SO2 Absorption Cross Sections and VUV N2 Oscillator Strengths for Planetary Atmospheres Studies

    NASA Astrophysics Data System (ADS)

    Smith, P. L.; Stark, G.; Rufus, J.

    2000-10-01

    The determination of the chemical composition of the atmosphere of Io in the 190-220 nm wavelength region requires a knowledge of the photoabsorption cross section of SO2 at temperatures ranging from 110 to 300 K. We are continuing our laboratory program to measure SO2 absorption cross sections with very high resolving power (450,000) at a range of temperatures appropriate to the Io atmosphere. Previous photoabsorption measurements have been unable to resolve the very congested SO2 spectrum. Out measurements are being undertaken at Imperial College, London, using an ultraviolet Fourier transform spectrometer. We recently completed room temperature measurements of SO2 cross sections in the 190-220 nm region (Stark et al., JGR Planets 104, 16,585 (1999)). Current laboratory work is focusing on a complementary set of measurements at 160 K. Preliminary results will be presented. Analyses of Voyager VUV occultation measurements of the N2-rich atmospheres of Titan and Triton are hampered by the lack of fundamental spectroscopic data for N2, in particular, by the lack of reliable f-values and line widths for electronic bands of N2 in the 80-100 nm wavelength region. We are continuing our program to measure band oscillator strengths for about 100 N2 bands between 80-100 nm. We have begun an on-line molecular spectroscopic atlas [http://cfa-www.harvard.edu/amdata/ampdata/N2ARCHIVE/n2home.html]. The archive includes published and unpublished 14N2, 14N15N, and 15N2 line lists and spectroscopic identifications, excited state energy levels, band and line f-values, a summary of published band f-value and line width measurements, and a cross-referenced summary of the relevant N2 literature. The listings are searchable by wavelength interval or band identification and are suitable for down-loading in a convenient format. This work was supported in part by NASA Grant NAG5-6222 and the Smithsonian Institution Atherton Seidel Grant Program.

  9. Age-related reduction and independent predictors of toe flexor strength in middle-aged men.

    PubMed

    Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Iwase, Mitsunori; Yokochi, Takashi

    2017-01-01

    Toe flexor muscles play an important role in posture and locomotion, and poor toe flexor strength is a risk factor for falls. In this cross-sectional study, we estimated the age-related change in toe flexor strength and compared it with that of handgrip strength. Independent factors predicting toe flexor and handgrip strength were also determined. A total of 1401 male (aged 35-59 years) study participants were divided into five groups according to their chronological age; 35-39, 40-44, 45-49, 50-54, and 55-59 years. Toe flexor and handgrip strength, anthropometry, and resting blood pressure were measured. Fasting blood samples were collected to measure blood glucose, triglycerides, high- and low-density lipoprotein-cholesterols, and albumin. A self-administered lifestyle questionnaire was conducted. Decline in absolute toe flexor and handgrip strength began in the age groups 50-55 and 55-59 years, respectively. In comparison to the mean values of the youngest group, relative toe flexor strength (87.0 ± 26.6%) was significantly lower than handgrip strength (94.4 ± 13.1%) for the oldest group. Multiple regression analyses showed that independent factors predicting both toe flexor and handgrip strength were lean body mass, age, serum albumin, drinking habit, and fat mass. Additionally, fasting blood glucose, diastolic blood pressure, sleeping time and exercise habit were predicting factors of toe flexor strength but not of handgrip strength. Age-related reduction in toe flexor strength was earlier and greater than handgrip strength, and toe flexor strength reflects body composition and metabolic status.

  10. Modeling nonlinearities in MEMS oscillators.

    PubMed

    Agrawal, Deepak K; Woodhouse, Jim; Seshia, Ashwin A

    2013-08-01

    We present a mathematical model of a microelectromechanical system (MEMS) oscillator that integrates the nonlinearities of the MEMS resonator and the oscillator circuitry in a single numerical modeling environment. This is achieved by transforming the conventional nonlinear mechanical model into the electrical domain while simultaneously considering the prominent nonlinearities of the resonator. The proposed nonlinear electrical model is validated by comparing the simulated amplitude-frequency response with measurements on an open-loop electrically addressed flexural silicon MEMS resonator driven to large motional amplitudes. Next, the essential nonlinearities in the oscillator circuit are investigated and a mathematical model of a MEMS oscillator is proposed that integrates the nonlinearities of the resonator. The concept is illustrated for MEMS transimpedance-amplifier- based square-wave and sine-wave oscillators. Closed-form expressions of steady-state output power and output frequency are derived for both oscillator models and compared with experimental and simulation results, with a good match in the predicted trends in all three cases.

  11. BLOCKING OSCILLATOR DOUBLE PULSE GENERATOR CIRCUIT

    DOEpatents

    Haase, J.A.

    1961-01-24

    A double-pulse generator, particuiarly a double-pulse generator comprising a blocking oscillator utilizing a feedback circuit to provide means for producing a second pulse within the recovery time of the blocking oscillator, is described. The invention utilized a passive network which permits adjustment of the spacing between the original pulses derived from the blocking oscillator and further utilizes the original pulses to trigger a circuit from which other pulses are initiated. These other pulses are delayed and then applied to the input of the blocking oscillator, with the result that the output from the oscillator circuit contains twice the number of pulses originally initiated by the blocking oscillator itself.

  12. [Low-Frequency Flow Oscillation

    NASA Technical Reports Server (NTRS)

    Bragg, Michael B.

    1997-01-01

    The results of the research conducted under this grant are presented in detail in three Master theses, by Heinrich, Balow, and Broeren. Additional analysis of the experimental data can be found in two AIAA Journal articles and two conference papers. Citations for all of the studies' publications can be found in the bibliography which is attached. The objective of Heinrich's study was to document the low-frequency flow oscillation on the LRN-1007 airfoil, which had been previously observed at low Reynolds number, to determine its origin, and explore the phenomenon at higher Reynolds number. Heinrich performed detailed flow visualization on the airfoil using surface fluorescent oil and laser-sheet off-body visualization. A large leading-edge separation bubble and trailing-edge separation was identified on the airfoil just prior to the onset of the unsteady stall flow oscillation. From the laser-sheet data, the unsteady flow appeared as a massive boundary-layer separation followed by flow reattachment. Hot-wire data were taken in the wake to identify the presence of the flow oscillation and the dominant frequency. The oscillation was found in the flow from a Reynolds number of 0.3 to 1.3 x 10 exp 6. The Strouhal number based on airfoil projected height was nominally 0.02 and increased slightly with increasing Reynolds number and significantly with increasing airfoil angle of attack. Balow focused his research on the leading-edge separation bubble which was hypothesized to be the origin of the low-frequency oscillation. Initially, experimental measurements in the bubble at the onset of the low-frequency oscillation were attempted to study the characteristics of the bubble and explain possible relationships to the shear-layer-flapping phenomena. Unfortunately, the bubble proved to be extremely sensitive to the probe interference and it drastically reduced the size of the bubble. These detailed measurements were then abandoned by Balow. However, this led to a series of

  13. Indications of stellar prominence oscillations on fast rotating stars: the cases of HK Aqr and PZ Tel

    NASA Astrophysics Data System (ADS)

    Leitzinger, M.; Odert, P.; Zaqarashvili, T. V.; Greimel, R.; Hanslmeier, A.; Lammer, H.

    2016-11-01

    We present the analysis of six nights of spectroscopic monitoring of two young and fast rotating late-type stars, namely the dMe star HK Aqr and the dG/dK star PZ Tel. On both stars, we detect absorption features reminiscent of signatures of corotating cool clouds or prominences visible in Hα. Several prominences on HK Aqr show periodic variability in the prominence tracks which follow a sinusoidal motion (indication of prominence oscillations). On PZ Tel, we could not find any periodic variability in the prominence tracks. By fitting sinusoidal functions to the prominence tracks, we derive amplitudes and periods which are similar to those of large-amplitude oscillations seen in solar prominences. In one specific event, we also derive a periodic variation of the prominence track in the Hβ spectral line which shows an anti-phase variation with the one derived for the Hα spectral line. Using these parameters and estimated mass density of a prominence on HK Aqr, we derive a minimum magnetic field strength of ˜2 G. The relatively low strength of the magnetic field is explained by the large height of this stellar prominence (≥ 0.67 stellar radii above the surface).

  14. Pseudo Landau levels and quantum oscillations in strained Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Alisultanov, Z. Z.

    2018-05-01

    The crystal lattice deformation in Weyl materials where the two chiralities are separated in momentum space leads to the appearance of gauge pseudo-fields. We investigated the pseudo-magnetic field induced quantum oscillations in strained Weyl semimetal (WSM). In contrast to all previous works on this problem, we use here a more general tilted Hamiltonian. Such Hamiltonian, seems to be is more suitable for a strained WSMs. We have shown that a pseudo-magnetic field induced magnetization of strained WSM is nonzero due to the fact that electric field (gradient of the deformation potential) is induced simultaneously with the pseudo-magnetic field. This related with fact that the pseudo Landau levels (LLs) in strained WSM are differ in vicinities of different WPs due to the presence of tilt in spectrum. Such violation of the equivalence between Weyl points (WPs) leads to modulation of quantum oscillations. We also showed that magnetization magnitude can be changed by application of an external electric field. In particular, it can be reduced to zero. The possibility of controlling of the magnetization by an electric field is interesting both from a fundamental point of view (a new type of magneto-electric effect) and application point of view (additional possibility to control diamagnetism of deformed WSMs). Finally, a coexistence of type-I and type-II Weyl fermions is possible in the system under investigation. Such phase is absolutely new for physics of topological systems.

  15. Tailored Welding Technique for High Strength Al-Cu Alloy for Higher Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Biradar, N. S.; Raman, R.

    AA2014 aluminum alloy, with 4.5% Cu as major alloying element, offers highest strength and hardness values in T6 temper and finds extensive use in aircraft primary structures. However, this alloy is difficult to weld by fusion welding because the dendritic structure formed can affect weld properties seriously. Among the welding processes, AC-TIG technique is largely used for welding. As welded yield strength was in the range of 190-195 MPa, using conventional TIG technique. Welding metallurgy of AA2014 was critically reviewed and factors responsible for lower properties were identified. Square-wave AC TIG with Transverse mechanical arc oscillation (TMAO) was postulated to improve the weld strength. A systematic experimentation using 4 mm thick plates produced YS in the range of 230-240 MPa, has been achieved. Through characterization including optical and SEM/EDX was conducted to validate the metallurgical phenomena attributable to improvement in weld properties.

  16. Electric field strength determination in filamentary DBDs by CARS-based four-wave mixing

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Kettlitz, Manfred; Brandenburg, Ronny; Hoeft, Hans; Czarnetzki, Uwe

    2016-09-01

    The electric field strength is a basic parameter of non-thermal plasmas. Therefore, a profound knowledge of the electric field distribution is crucial. In this contribution a four wave mixing technique based on Coherent Anti-Stokes Raman spectroscopy (CARS) is used to measure electric field strengths in filamentary dielectric barrier discharges (DBDs). The discharges are operated with a pulsed voltage in nitrogen at atmospheric pressure. Small amounts hydrogen (10 vol%) are admixed as tracer gas to evaluate the electric field strength in the 1 mm discharge gap. Absolute values of the electric field strength are determined by calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. Alteration of the electric field strength has been observed during the internal polarity reversal and the breakdown process. In this case the major advantage over emission based methods is that this technique can be used independently from emission, e.g. in the pre-phase and in between two consecutive, opposite discharge pulses where no emission occurs at all. This work was supported by the Deutsche Forschungsgemeinschaft, Forschergruppe FOR 1123 and Sonderforschungsbereich TRR 24 ``Fundamentals of complex plasmas''.

  17. Programmable Oscillator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Lee, Clement G.; Nguyen, Huy

    2011-01-01

    A programmable oscillator is a frequency synthesizer with an output phase that tracks an arbitrary function. An offset, phase-locked loop circuit is used in combination with an error control feedback loop to precisely control the output phase of the oscillator. To down-convert the received signal, several stages of mixing may be employed with the compensation for the time-base distortion of the carrier occurring at any one of those stages. In the Goldstone Solar System Radar (GSSR), the compensation occurs in the mixing from an intermediate frequency (IF), whose value is dependent on the station and band, to a common IF used in the final stage of down-conversion to baseband. The programmable oscillator (PO) is used in the final stage of down-conversion to generate the IF, along with a time-varying phase component that matches the time-base distortion of the carrier, thus removing it from the final down-converted signal.

  18. Canard and mixed mode oscillations in an excitable glow discharge plasma in the presence of inhomogeneous magnetic field

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

    Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Sekar Iyengar, A. N., E-mail: ansekar.iyengar@saha.ac.in; Nurujjaman, Md., E-mail: jaman-nonlinear@yahoo.co.in

    2015-12-15

    We report on the experimental observation of canard orbit and mixed mode oscillations (MMOs) in an excitable glow discharge plasma induced by an external magnetic field perturbation using a bar magnet. At a small value of magnetic field, small amplitude quasiperiodic oscillations were excited, and with the increase in the magnetic field, large amplitude oscillations were excited. Analyzing the experimental results, it seems that the magnetic field could be playing the role of noise for such nonlinear phenomena. It is observed that the noise level increases with the increase in magnetic field strength. The experimental results have also been corroboratedmore » by a numerical simulation using a FitzHugh-Nagumo like macroscopic model derived from the basic plasma equations and phenomenology, where the noise has been included to represent the internal plasma noise. This macroscopic model shows MMO in the vicinity of the canard point when an external noise is added.« less

  19. Surface oscillation of levitated liquid droplets under microgravity

    NASA Astrophysics Data System (ADS)

    Watanabe, Masahito; Hibiya, Taketoshi; Ozawa, Shumpei; Mizuno, Akitoshi

    2012-07-01

    Microgravity conditions have advantages of measurement of surface tension and viscosity of metallic liquids by the oscillating drop method with an electromagnetic levitation (EML) device. Thus, we are now planning the thermophysical properties, the surface tension, viscosity, density and etc., measurements of liquid alloys using the electromagnetic levitator named MSL-EML (Materials Science Laboratory Electromagnetic Levitator), which ahs been developed by the European Space Agency (ESA), installed in the International Space Station (ISS). The surface tension and the viscosity of liquid samples by the oscillating drop method are obtained from the surface oscillation frequency and damping time of surface oscillation respectively. However, analysis of oscillating drop method in EML must be improved even in the microgravity conditions, because on the EML conditions the electromagnetic force (EMF) cannot generate the surface oscillation with discretely oscillation mode. Since under microgravity the levitated droplet shape is completely spherical, the surface oscillation frequency with different oscillation modes degenerates into the single frequency. Therefore, surface tension will be not affected the EML condition under microgravity, but viscosity will be affected on the different oscillation mode of surface oscillations. Because dumping time of surface oscillation of liquid droplets depends on the oscillation modes, the case of surface oscillation including multi oscillation modes the viscosity values obtained from dumping time will be modified from the correct viscosity. Therefore, we investigate the dumping time of surface oscillation of levitated droplets with different oscillation modes and also with including multi oscillation modes using the electrostatic levitation (ESL) on ground and EML under microgravity conditions by the parabolic flight of airplane. The ESL can discretely generate the surface oscillation with different oscillation modes by the change of

  20. Primordial oscillations in life: Direct observation of glycolytic oscillations in individual HeLa cervical cancer cells

    NASA Astrophysics Data System (ADS)

    Amemiya, Takashi; Shibata, Kenichi; Itoh, Yoshihiro; Itoh, Kiminori; Watanabe, Masatoshi; Yamaguchi, Tomohiko

    2017-10-01

    We report the first direct observation of glycolytic oscillations in HeLa cervical cancer cells, which we regard as primordial oscillations preserved in living cells. HeLa cells starved of glucose or both glucose and serum exhibited glycolytic oscillations in nicotinamide adenine dinucleotide (NADH), exhibiting asynchronous intercellular behaviors. Also found were spatially homogeneous and inhomogeneous intracellular NADH oscillations in the individual cells. Our results demonstrate that starved HeLa cells may be induced to exhibit glycolytic oscillations by either high-uptake of glucose or the enhancement of a glycolytic pathway (Crabtree effect or the Warburg effect), or both. Their asynchronous collective behaviors in the oscillations were probably due to a weak intercellular coupling. Elucidation of the relationship between the mechanism of glycolytic dynamics in cancer cells and their pathophysiological characteristics remains a challenge in future.

  1. Recent progress in opto-electronic oscillator

    NASA Technical Reports Server (NTRS)

    Maleki, Lute

    2005-01-01

    The optoelectronic oscillator (OEO) is a unique device based on photonics techniques to generate highly spectrally pure microwave signals [1]. The development of the OEO was motivated by the need for high performance oscillators in the frequency range larger than 10 GHz, where conventional electronic oscillators have a number of limitations. These limitations typically stem from the product of fQ, where f is the oscillator frequency and Q is the quality factor of the resonator in the oscillator. In conventional resonators, whether electromagnetic or piezoelectric, this product is usually a constant. Thus, as the oscillator frequency is pushed higher, the quality factor degrades, resulting in degradation of the phase noise of the oscillator. An approach to mitigate the problem is to start with a very high quality signal in the 5 to 100 MHz range generated by a quartz oscillator and multiply the frequency to achieve the desired microwave signal. Here again, frequency multiplication also results in an increase of the phase noise by a factor of 2010gN, where N is the multiplication factor.

  2. Large-amplitude Longitudinal Oscillations Triggered by the Merging of Two Solar Filaments: Observations and Magnetic Field Analysis

    NASA Astrophysics Data System (ADS)

    Luna, M.; Su, Y.; Schmieder, B.; Chandra, R.; Kucera, T. A.

    2017-12-01

    We follow the eruption of two related intermediate filaments observed in Hα (from GONG) and EUV (from Solar Dynamics Observatory SDO/Atmospheric Imaging assembly AIA) and the resulting large-amplitude longitudinal oscillations of the plasma in the filament channels. The events occurred in and around the decayed active region AR12486 on 2016 January 26. Our detailed study of the oscillation reveals that the periods of the oscillations are about one hour. In Hα, the period decreases with time and exhibits strong damping. The analysis of 171 Å images shows that the oscillation has two phases: an initial long-period phase and a subsequent oscillation with a shorter period. In this wavelength, the damping appears weaker than in Hα. The velocity is the largest ever detected in a prominence oscillation, approximately 100 {km} {{{s}}}-1. Using SDO/HMI magnetograms, we reconstruct the magnetic field of the filaments, modeled as flux ropes by using a flux-rope insertion method. Applying seismological techniques, we determine that the radii of curvature of the field lines in which cool plasma is condensed are in the range 75-120 Mm, in agreement with the reconstructed field. In addition, we infer a field strength of ≥7 to 30 Gauss, depending on the electron density assumed, that is also in agreement with the values from the reconstruction (8-20 Gauss). The poloidal flux is zero and the axis flux is on the order of 1020 to 1021 Mx, confirming the high shear existing even in a non-active filament.

  3. Active-bridge oscillator

    DOEpatents

    Wessendorf, Kurt O.

    2001-01-01

    An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.

  4. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

    1992-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators, or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  5. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

    Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

    1993-01-01

    Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

  6. Polymerization and oscillation stuttering in a filamentous model of the subcellular Min oscillation

    NASA Astrophysics Data System (ADS)

    Rutenberg, Andrew; Sengupta, Supratim; Sain, Anirban; Derr, Julien

    2011-03-01

    We present a computational model of the E. coli Min oscillation that involves polymerization of MinD filaments followed by depolymerization stimulated by filament-end zones of MinE. Our stochastic model is fully three-dimensional, and tracks the diffusion and interactions of every MinD and MinE molecule. We recover self-organized Min oscillations. We investigate the experimental phenomenon of oscillation stuttering, which we relate to the disruption of MinE tip-binding at the filament scale.

  7. Oscillations in stellar atmospheres

    NASA Technical Reports Server (NTRS)

    Costa, A.; Ringuelet, A. E.; Fontenla, J. M.

    1989-01-01

    Atmospheric excitation and propagation of oscillations are analyzed for typical pulsating stars. The linear, plane-parallel approach for the pulsating atmosphere gives a local description of the phenomenon. From the local analysis of oscillations, the minimum frequencies are obtained for radially propagating waves. The comparison of the minimum frequencies obtained for a variety of stellar types is in good agreement with the observed periods of the oscillations. The role of the atmosphere in the globar stellar pulsations is thus emphasized.

  8. Neuromorphic computing with nanoscale spintronic oscillators.

    PubMed

    Torrejon, Jacob; Riou, Mathieu; Araujo, Flavio Abreu; Tsunegi, Sumito; Khalsa, Guru; Querlioz, Damien; Bortolotti, Paolo; Cros, Vincent; Yakushiji, Kay; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, Mark D; Grollier, Julie

    2017-07-26

    Neurons in the brain behave as nonlinear oscillators, which develop rhythmic activity and interact to process information. Taking inspiration from this behaviour to realize high-density, low-power neuromorphic computing will require very large numbers of nanoscale nonlinear oscillators. A simple estimation indicates that to fit 10 8 oscillators organized in a two-dimensional array inside a chip the size of a thumb, the lateral dimension of each oscillator must be smaller than one micrometre. However, nanoscale devices tend to be noisy and to lack the stability that is required to process data in a reliable way. For this reason, despite multiple theoretical proposals and several candidates, including memristive and superconducting oscillators, a proof of concept of neuromorphic computing using nanoscale oscillators has yet to be demonstrated. Here we show experimentally that a nanoscale spintronic oscillator (a magnetic tunnel junction) can be used to achieve spoken-digit recognition with an accuracy similar to that of state-of-the-art neural networks. We also determine the regime of magnetization dynamics that leads to the greatest performance. These results, combined with the ability of the spintronic oscillators to interact with each other, and their long lifetime and low energy consumption, open up a path to fast, parallel, on-chip computation based on networks of oscillators.

  9. Can absolute and proportional anthropometric characteristics distinguish stronger and weaker powerlifters?

    PubMed

    Keogh, Justin W L; Hume, Patria A; Pearson, Simon N; Mellow, Peter J

    2009-11-01

    This study sought to compare the anthropometric profiles of 17 weaker and 17 stronger Australasian and Pacific powerlifters who had competed in a regional-, national-, or international-level powerlifting competition in New Zealand. Stronger lifters were defined as those having a Wilks score greater than 410, whereas those in the weaker group had a Wilks score less than 370. Each powerlifter was assessed for 37 anthropometric dimensions by International Society for the Advancement of Kinanthropometry (ISAK) level II and III accredited anthropometrists. Because all powerlifters were highly mesomorphic and possessed large girths and bone breadths, both in absolute terms and when expressed as Phantom-Z scores compared through the Phantom, relatively few significant anthropometric differences were observed. However, stronger lifters had significantly greater muscle mass and larger muscular girths in absolute terms as well as greater Brugsch Index (chest girth/height) and "Phantom"-normalized muscle mass, upper arm, chest, and forearm girths. In terms of the segment lengths and bone breadths, the only significant difference was that stronger lifters had a significantly shorter lower leg than weaker lifters. Because the majority of the significant differences were for muscle mass and muscular girths, it would appear likely that these differences contributed to the stronger lifters' superior performance. Powerlifters may therefore need to devote some of their training to the development of greater levels of muscular hypertrophy if they wish to continue to improve their performance. To better understand the anthropometric determinants of muscular strength, future research should recruit larger samples (particularly of elite lifters) and follow these subjects prospectively.

  10. Investigations of the middle atmospheric thermal structure and oscillations over sub-tropical regions in the Northern and Southern Hemispheres

    NASA Astrophysics Data System (ADS)

    Sharma, Som; Kumar, Prashant; Jethva, Chintan; Vaishnav, Rajesh; Bencherif, Hassan

    2017-06-01

    The temperature retrieved from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) onboard Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite during January 2002 to September 2015 are used in this study to delineate the differences of middle atmospheric thermal structure in the Northern Hemisphere (NH) and Southern Hemisphere (SH). Two stations namely Mt. Abu (24.59°N, 72.70°E) in NH and Reunion Island (21.11°S, 55.53°E) in SH are chosen over sub-tropical regions. Temperature climatology from SABER observations suggests that stratopause is warmer, and upper mesosphere is cooler in NH as compared to SH. Three atmospheric models are used to understand the monthly thermal structure differences for different altitudes. Moreover, semi-annual, annual and quasi-biennial oscillations are studied using Lomb Scargle Periodogram and Wavelet transform techniques. Over NH, summer and winter season are warmer ( 4 K) and cooler ( 3 K) respectively in stratosphere as compared to SH. It is important to note here that Mt. Abu temperature is warmer ( 9 K) than Reunion Island in winter but in summer season Mt. Abu temperature is cooler in upper mesosphere and above mesosphere NH shows warming. Results show that annual oscillations are dominated in both hemisphere as compared to semi-annual and quasi-biennial oscillations. In upper mesosphere, strength of annual oscillations is substantial in NH, while semi-annual oscillations are stronger in SH. Wavelet analyses found that annual oscillations are significant in NH near mesopause, while semi-annual oscillations are strengthening in SH.

  11. Transverse Oscillations of Coronal Loops

    NASA Astrophysics Data System (ADS)

    Ruderman, Michael S.; Erdélyi, Robert

    2009-12-01

    On 14 July 1998 TRACE observed transverse oscillations of a coronal loop generated by an external disturbance most probably caused by a solar flare. These oscillations were interpreted as standing fast kink waves in a magnetic flux tube. Firstly, in this review we embark on the discussion of the theory of waves and oscillations in a homogeneous straight magnetic cylinder with the particular emphasis on fast kink waves. Next, we consider the effects of stratification, loop expansion, loop curvature, non-circular cross-section, loop shape and magnetic twist. An important property of observed transverse coronal loop oscillations is their fast damping. We briefly review the different mechanisms suggested for explaining the rapid damping phenomenon. After that we concentrate on damping due to resonant absorption. We describe the latest analytical results obtained with the use of thin transition layer approximation, and then compare these results with numerical findings obtained for arbitrary density variation inside the flux tube. Very often collective oscillations of an array of coronal magnetic loops are observed. It is natural to start studying this phenomenon from the system of two coronal loops. We describe very recent analytical and numerical results of studying collective oscillations of two parallel homogeneous coronal loops. The implication of the theoretical results for coronal seismology is briefly discussed. We describe the estimates of magnetic field magnitude obtained from the observed fundamental frequency of oscillations, and the estimates of the coronal scale height obtained using the simultaneous observations of the fundamental frequency and the frequency of the first overtone of kink oscillations. In the last part of the review we summarise the most outstanding and acute problems in the theory of the coronal loop transverse oscillations.

  12. Coherent signal amplification in bistable nanomechanical oscillators by stochastic resonance

    NASA Astrophysics Data System (ADS)

    Badzey, Robert L.; Mohanty, Pritiraj

    2005-10-01

    Stochastic resonance is a counterintuitive concept: the addition of noise to a noisy system induces coherent amplification of its response. First suggested as a mechanism for the cyclic recurrence of ice ages, stochastic resonance has been seen in a wide variety of macroscopic physical systems: bistable ring lasers, superconducting quantum interference devices (SQUIDs), magnetoelastic ribbons and neurophysiological systems such as the receptors in crickets and crayfish. Although fundamentally important as a mechanism of coherent signal amplification, stochastic resonance has yet to be observed in nanoscale systems. Here we report the observation of stochastic resonance in bistable nanomechanical silicon oscillators. Our nanomechanical systems consist of beams that are clamped at each end and driven into transverse oscillation with the use of a radiofrequency source. Modulation of the source induces controllable switching of the beams between two stable, distinct states. We observe that the addition of white noise causes a marked amplification of the signal strength. Stochastic resonance in nanomechanical systems could have a function in the realization of controllable high-speed nanomechanical memory cells, and paves the way for exploring macroscopic quantum coherence and tunnelling.

  13. Combustor oscillating pressure stabilization and method

    DOEpatents

    Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.H.; Cully, S.R.; Addis, R.E.

    1998-08-11

    High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time. 7 figs.

  14. Rhythmic Activity and Individual Variability in Recognition Memory: Theta Oscillations Correlate with Performance whereas Alpha Oscillations Correlate with ERPs.

    PubMed

    Chen, Yvonne Y; Caplan, Jeremy B

    2017-01-01

    During study trials of a recognition memory task, alpha (∼10 Hz) oscillations decrease, and concurrently, theta (4-8 Hz) oscillations increase when later memory is successful versus unsuccessful (subsequent memory effect). Likewise, at test, reduced alpha and increased theta activity are associated with successful memory (retrieval success effect). Here we take an individual-differences approach to test three hypotheses about theta and alpha oscillations in verbal, old/new recognition, measuring the difference in oscillations between hit trials and miss trials. First, we test the hypothesis that theta and alpha oscillations have a moderately mutually exclusive relationship; but no support for this hypothesis was found. Second, we test the hypothesis that theta oscillations explain not only memory effects within participants, but also individual differences. Supporting this prediction, durations of theta (but not alpha) oscillations at study and at test correlated significantly with d' across participants. Third, we test the hypothesis that theta and alpha oscillations reflect familiarity and recollection processes by comparing oscillation measures to ERPs that are implicated in familiarity and recollection. The alpha-oscillation effects correlated with some ERP measures, but inversely, suggesting that the actions of alpha oscillations on memory processes are distinct from the roles of familiarity- and recollection-linked ERP signals. The theta-oscillation measures, despite differentiating hits from misses, did not correlate with any ERP measure; thus, theta oscillations may reflect elaborative processes not tapped by recollection-related ERPs. Our findings are consistent with alpha oscillations reflecting visual inattention, which can modulate memory, and with theta oscillations supporting recognition memory in ways that complement the most commonly studied ERPs.

  15. Cardiopulmonary fitness and muscle strength in patients with osteogenesis imperfecta type I.

    PubMed

    Takken, Tim; Terlingen, Heike C; Helders, Paul J M; Pruijs, Hans; Van der Ent, Cornelis K; Engelbert, Raoul H H

    2004-12-01

    To evaluate cardiopulmonary function, muscle strength, and cardiopulmonary fitness (VO 2 peak) in patients with osteogenesis imperfecta (OI). In 17 patients with OI type I (mean age 13.3 +/- 3.9 years) cardiopulmonary function was assessed at rest using spirometry, plethysmography, electrocardiography, and echocardiography. Exercise capacity was measured using a maximal exercise test on a bicycle ergometer and an expired gas analysis system. Muscle strength in shoulder abductors, hip flexors, ankle dorsal flexor, and grip strength were measured. All results were compared with reference values. Cardiopulmonary function at rest was within normal ranges, but when it was compared with normal height for age and sex, vital capacities were reduced. Mean absolute and relative VO 2 peak were respectively -1.17 (+/- 0.67) and -1.41 (+/- 1.52) standard deviations lower compared with reference values ( P < .01). Muscle strength also was significantly reduced in patients with OI, ranging from -1.24 +/- 1.40 to -2.88 +/- 2.67 standard deviations lower compared with reference values. In patients with OI type I, no pulmonary or cardiac abnormalities at rest were found. The exercise tolerance and muscle strength were significantly reduced in patients with OI, which might account for their increased levels of fatigue during activities of daily living.

  16. VOLTAGE-CONTROLLED TRANSISTOR OSCILLATOR

    DOEpatents

    Scheele, P.F.

    1958-09-16

    This patent relates to transistor oscillators and in particular to those transistor oscillators whose frequencies vary according to controlling voltages. A principal feature of the disclosed transistor oscillator circuit resides in the temperature compensation of the frequency modulating stage by the use of a resistorthermistor network. The resistor-thermistor network components are selected to have the network resistance, which is in series with the modulator transistor emitter circuit, vary with temperature to compensate for variation in the parameters of the transistor due to temperature change.

  17. Travelling waves in somitogenesis: Collective cellular properties emerge from time-delayed juxtacrine oscillation coupling.

    PubMed

    Tomka, Tomas; Iber, Dagmar; Boareto, Marcelo

    2018-04-24

    The sculpturing of the vertebrate body plan into segments begins with the sequential formation of somites in the presomitic mesoderm (PSM). The rhythmicity of this process is controlled by travelling waves of gene expression. These kinetic waves emerge from coupled cellular oscillators and sweep across the PSM. In zebrafish, the oscillations are driven by autorepression of her genes and are synchronized via Notch signalling. Mathematical modelling has played an important role in explaining how collective properties emerge from the molecular interactions. Increasingly more quantitative experimental data permits the validation of those mathematical models, yet leads to increasingly more complex model formulations that hamper an intuitive understanding of the underlying mechanisms. Here, we review previous efforts, and design a mechanistic model of the her1 oscillator, which represents the experimentally viable her7;hes6 double mutant. This genetically simplified system is ideally suited to conceptually recapitulate oscillatory entrainment and travelling wave formation, and to highlight open questions. It shows that three key parameters, the autorepression delay, the juxtacrine coupling delay, and the coupling strength, are sufficient to understand the emergence of the collective period, the collective amplitude, and the synchronization of neighbouring Her1 oscillators. Moreover, two spatiotemporal time delay gradients, in the autorepression and in the juxtacrine signalling, are required to explain the collective oscillatory dynamics and synchrony of PSM cells. The highlighted developmental principles likely apply more generally to other developmental processes, including neurogenesis and angiogenesis. Copyright © 2018. Published by Elsevier Ltd.

  18. Midfrontal conflict-related theta-band power reflects neural oscillations that predict behavior.

    PubMed

    Cohen, Michael X; Donner, Tobias H

    2013-12-01

    Action monitoring and conflict resolution require the rapid and flexible coordination of activity in multiple brain regions. Oscillatory neural population activity may be a key physiological mechanism underlying such rapid and flexible network coordination. EEG power modulations of theta-band (4-8 Hz) activity over the human midfrontal cortex during response conflict have been proposed to reflect neural oscillations that support conflict detection and resolution processes. However, it has remained unclear whether this frequency-band-specific activity reflects neural oscillations or nonoscillatory responses (i.e., event-related potentials). Here, we show that removing the phase-locked component of the EEG did not reduce the strength of the conflict-related modulation of the residual (i.e., non-phase-locked) theta power over midfrontal cortex. Furthermore, within-subject regression analyses revealed that the non-phase-locked theta power was a significantly better predictor of the conflict condition than was the time-domain phase-locked EEG component. Finally, non-phase-locked theta power showed robust and condition-specific (high- vs. low-conflict) cross-trial correlations with reaction time, whereas the phase-locked component did not. Taken together, our results indicate that most of the conflict-related and behaviorally relevant midfrontal EEG signal reflects a modulation of ongoing theta-band oscillations that occurs during the decision process but is not phase-locked to the stimulus or to the response.

  19. On the relationship between the stratospheric quasi-biennial oscillation and the tropospheric Southern oscillation

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

    Xu, J.S.

    1992-05-01

    Two quasi-periodic oscillations in the tropical atmosphere with similar oscillation period-the stratospheric quasi-biennial and the Southern oscillations-and the relationship between these two oscillations are examined using the Principal Oscillation Pattern (POP) analysis technique. The POP analysis of the equatorial stratospheric dataset provides a compact description of the QBO. The oscillation features identified by the POP analysis, namely, the spatial structure, the characteristic times of the oscillation, and the asymmetry in downward propagation, are almost identical to those found by earlier studies using more conventional analyses. The simultaneous POP analysis of the equatorial zonal surface wind and sea surface temperature indicatesmore » a well-defined cyclic behavior of the SO. In contrast to the very regular QBO, the SO appears to be much more noisy with intermittent quiet phases. A spectral analysis of the complex POP coefficient time series and the SO index reveals a negligible correlation between the two processes. A POP analysis of the combined equatorial dataset of stratospheric wind, zonal surface wind, and SST also indicates no relation between the QBO and the SO. Two independent modes are identified, one of them completely describing the QBO and the other representing the entire SO. No linear relationship is found between the two modes either in space or in time. It is concluded that the SO and the QBO are two independent processes in the tropical atmosphere with similar time scales. 26 refs., 17 figs.« less

  20. Using, Seeing, Feeling, and Doing Absolute Value for Deeper Understanding

    ERIC Educational Resources Information Center

    Ponce, Gregorio A.

    2008-01-01

    Using sticky notes and number lines, a hands-on activity is shared that anchors initial student thinking about absolute value. The initial point of reference should help students successfully evaluate numeric problems involving absolute value. They should also be able to solve absolute value equations and inequalities that are typically found in…