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Sample records for 2s2 1s0 transition

  1. Studies of Yb ^1S0 -- ^3P0 clock transitions

    NASA Astrophysics Data System (ADS)

    Hong, Tao

    2005-05-01

    We are exploring two quite different methods for observing the ultra-sharp 6s^2 ^1S0 -- 6s6p ^3P0 optical interval in atomic Yb, which is considered a primary candidate for future optical frequency standards [1].In the first method, we observe the 578 nm single photon transition allowed in the odd isotopes through internal hyperfine coupling of the nuclear spin.† We shine a 578 nm laser beam on cold Yb atoms held in a magneto-optical trap (MOT), and detect a decrease in MOT fluorescence when the laser is resonant with the clock transition.† Our second approach is to use the even Yb isotopes, connecting the ^1S0 and ^3P0 states† by† a multi- photon transition [2]. Sharp electromagnetically induced transparency and absorption (EITA) resonance features appear when the photon frequencies combine to equal† the ^1S0 -- ^3P0 clock interval.† We will describe our initial studies of† 2 and 3 photon resonances in Yb, including Doppler-free 3 photon EITA. [1]S. G.† Porsev, A. Derevianko, E. N. Fortson, Phys. Rev. A 69, 021403(R)† (2004); H. Katori, in Proc. 6th Symposium Frequency Standards and Metrology, edited by P. Gill (World Scienti.c, Singapore, 2002), pp. 323-330 [2]Tao Hong, Claire Cramer, Warren Nagourney, E. N. Fortson, physics/0409051 and to be published in Phys. Rev. Lett.; Robin Santra, Ennio Arimondo, Tetsuya Ido, Crhis H. Greene, Jun Ye, physics/0411197

  2. Spectroscopy of 1S0- 3P1 transition of magnesium atom in an external absorption cell

    NASA Astrophysics Data System (ADS)

    Bagayev, S. N.; Baraulya, V. I.; Bonert, A. E.; Goncharov, A. N.; Seydaliev, M. R.

    2001-09-01

    The results of saturated absorption spectroscopy of the intercombination 1S0- 3P1 transition of magnesium atoms at 457 nm in an external absorption cell are presented. A laser system based on a Ti:Sa laser with frequency doubling in a LBO nonlinear crystal was used in these experiments. Saturated absorption resonances of magnesium in an external cell at the 1S0- 3P1 transition have been obtained for the first time. Pressure broadening of resonances equal to 12.5±1.5 kHz/mTorr has been measured.

  3. Spectroscopy of the forbidden 1S0 -->3P0 transition on ultra-cold ytterbium atoms

    NASA Astrophysics Data System (ADS)

    Dareau, Alexandre; Scholl, Matthias; Beaufils, Quentin; Döring, Daniel; Beugnon, Jérôme; Gerbier, Fabrice

    2015-05-01

    Cold atoms in optical lattices are often considered a rich playground for emulating condensed matter systems, since they make it possible to engineer many-body Hamiltonians with tunable parameters. However, one missing feature is the ability to emulate orbital magnetism. Recent proposals for simulating orbital magnetism with neutral atoms rely on a state-dependent optical lattice with laser-driven hopping. Ytterbium, with its long lived metastable state (3P0), is a well-suited candidate for the implementation of such schemes. Addressing the forbidden transition between ytterbium ground (1S0) and meta-stable (3P0) states is experimentally challenging, and requires the use of a laser with stability close to the standards of atomic clocks. I will report on the building of a ultra-narrow laser locked on a high-finesse low-expansion cavity. I will then show how the absolute frequency of the cavity modes can be calibrated by performing high-resolution spectroscopy on molecular iodine, allowing us perform Doppler spectroscopy on the 1S0 -->3P0 transition of an ytterbium BEC.

  4. Photoassociation spectroscopy of 174 Yb Bose-Einstein Condensate using the 1 S0<-->3 P1 transition

    NASA Astrophysics Data System (ADS)

    Mun, Jongchul; Lee, Jeongwon; Lee, Jae Hoon; Kim, Min-Seok; Shin, Yong-Il

    2016-05-01

    We studied the photoassociation spectrum of 174 Yb Bose-Einstein condensate (BEC) using an optical Feshbach resonance near the intercombination transition (1 S0 -3 P1, 578 nm). The optical length lopt, which characterize the interaction strength of optical Feshbach resonances, of four least-bound molecular levels (ν' = - 1 ~ - 4) were precisely determined by measuring the two-body loss rate at various optical powers. We also found the parameter η =Γspon /Γmol , which characterizes the enhancement of molecular loss, to be > 1 as in the previous studies. Our BEC apparatus and experimental scheme are also introduced in this presentation. This work was supported by KRISS creative research initiative.

  5. Fast relaxation of the metastable helium state 2 1 S 0 in collisions with molecules and collisional lasing on the He (2 1 P 1 0 -2 1 S 0 ) transition

    NASA Astrophysics Data System (ADS)

    Belskaya, E. V.; Bokhan, P. A.; Zakrevsky, Dm. E.; Lavrukhin, M. A.

    2011-09-01

    In the present study, the laser absorption method was used to measure the rates of quenching of the metastable state He(2 1S0), the lower laser level in the self-terminating helium laser, with H2O, NH3, N2O, and CO2 molecules. For the above molecules, the quenching rate constants were found to equal (1.2 ± 0.3)10 - 9 , (0.8 ± 0.2)10 - 9 , (1.9 ± 0.2)10 - 9 and (2.2 ± 0.4)10 - 9 cm 3 s - 1 . Under excitation with long (up to 750 ns) open discharge generated electron beam pulses, lasing on the transition He (2 1P10-2 1S0) was examined. In the mixtures He-H2O and He-NH3, lasing durations almost equal to the pump-pulse duration were obtained. In the mixtures of He with CO2 and N2O, no lasing prolonged in comparison with pure helium was found. The data obtained were explained considering two quenching mechanisms for the state He(2 1S0): in collisions with molecules and in collisions with plasma electrons having low energies due to fast relaxation of the vibrational states of H2O and NH3 molecules.

  6. Observation and absolute frequency measurements of the 1S0-3P0 optical clock transition in neutral ytterbium.

    PubMed

    Hoyt, C W; Barber, Z W; Oates, C W; Fortier, T M; Diddams, S A; Hollberg, L

    2005-08-19

    We report the direct excitation of the highly forbidden (6s2) 1S0 <--> (6s6p) 3P0 optical transition in two odd isotopes of neutral ytterbium. As the excitation laser frequency is scanned, absorption is detected by monitoring the depletion from an atomic cloud at approximately 70 microK in a magneto-optical trap. The measured frequency in 171Yb (F=1/2) is 518,295,836,591.6 +/- 4.4 kHz. The measured frequency in 173Yb (F=5/2) is 518,294,576,847.6 +/- 4.4 kHz. Measurements are made with a femtosecond-laser frequency comb calibrated by the National Institute of Standards and Technology cesium fountain clock and represent nearly a 10(6)-fold reduction in uncertainty. The natural linewidth of these J=0 to J=0 transitions is calculated to be approximately 10 mHz, making them well suited to support a new generation of optical atomic clocks based on confinement in an optical lattice. PMID:16196856

  7. Transitions of the type 2s-2p in oxygenlike Y, Zr, and Nb

    NASA Technical Reports Server (NTRS)

    Behring, W. E.; Brown, C. M.; Feldman, U.; Seely, J. F.; Reader, J.

    1986-01-01

    Transitions of the type 2s-2p in the oxygenlike ions Y XXXII, Zr XXXIII, and Nb XXXIV were identified in spectra recorded at the University of Rochester's Omega laser facility. Solid targets were spherically irradiated by 24 beams of frequency-tripled (351-nm) Nd-glass laser radiation. The spectra were photographed with a 3-m grazing-incidence spectrograph. The identified transitions of the oxygenlike ions are in the range 30 to 73 A. The wavelengths for the magnetic-dipole transitions within the 2s2p4 ground configurations of these ions are predicted from the experimental energy levels.

  8. 2s2 2p5-2s2p6 transitions in fluorinelike ions from Zr(31+) to Sn(41+)

    NASA Technical Reports Server (NTRS)

    Reader, Joseph; Brown, C. M.; Ekberg, J. O.; Feldman, U.; Seely, J. F.; Behring, W. E.

    1986-01-01

    Transitions of the type 2s2 2p5-2s2p6 have been observed in eight fluorinelike ions from Zr(31+) to Sn(41+). The spectra were produced by focusing light from the Nd:glass Omega laser at the University of Rochester onto solid targets and photographing the resultant plasmas with a 3-m grazing-incidence spectrograph. The identified transitions are in the region 24-60 A. The measured wavelengths are in good agreement with wavelengths calculated with the semiempirical formulas of Edlen (1983). Wavelengths for the 2s2 2p5 2P3/2-2P1/2 magnetic-dipole transitions are given for each ion.

  9. Measurement of absolute cross sections for excitation of the 2s(2) S-1 -> 2s2p P-1 degrees transition in O+4

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Djuric, N.; Lozano, J. A.; Berrington, K. A.; Chutjian, A.

    2005-01-01

    Experimental cross sections are reported for the 1s(2)2s(2) S-1 -> 1s(2)2s2p P-1(o) transition in O+4 located at 19.689 eV. Use is made of the electron energy-loss method, using a merged electron-ion beam geometry. The center-of-mass interaction energies for the measurements in the S-1 -> P-1(o) transition are in the range 18 eV ( below the threshold) to 30 eV. Data are compared with other previous electron energy-loss measurements and with results of a 26 term R-matrix calculation that includes fine structure explicitly via the Breit-Pauli Hamiltonian. Clear resonance enhancement is observed in all experimental and theoretical results near the threshold for this S-1 -> P-1(o) transition.

  10. Optimization of Doppler-free magnetically induced dichroic locking spectroscopy on the 1S0-3P1 transition of a neutral mercury atom

    NASA Astrophysics Data System (ADS)

    Liu, Hongli; Yin, Shiqi; Qian, Jun; Xu, Zhen; Wang, Yuzhu

    2013-04-01

    Doppler-free dichroic locking (DFDL) spectroscopy on the 1S0-3P1 transition of neutral mercury (Hg) atoms is observed in a 5 mm long vapour cell. The performance of the DFDL signal, such as its slope and amplitude, is investigated in detail. The optimal axial magnetic field and cell temperature (optical depth) for the observed seven transitions are also highlighted. We also demonstrate an important application of DFDL spectroscopy in the frequency stabilization of an ultraviolet laser on the transition of 200Hg.

  11. 1s2s2p2 5p3 5S transition in B ii

    NASA Astrophysics Data System (ADS)

    Mannervik, S.; Cederquist, H.; Martinson, I.; Brage, T.; Froese Fischer, C.

    1987-04-01

    An experimental and theoretical study has been made of the 1s2s2p2 5P-1s2p3 5S transition in B ii. The experimental wavelength and lifetime (1323.92+/-0.07 Å and 0.65+/-0.01 ns), determined by beam-foil spectroscopy, are more than five times more accurate than previous experimental results. Our theoretical data, from multiconfiguration Hartree-Fock calculations, 1311.6 Å and 0.601 ns, are in excellent agreement with previous theoretical predictions of Beck and Nicolaides [Phys. Lett. 61A, 227 (1977)]. We have also observed the 1s2p3 5S-1s2p23s 5P transition, at 857.7+/-0.2 Å, in accord with the theoretical value 859.1 Å.

  12. Absolute frequency measurement of the ^1S0<->^3P0 clock transition at 578.4 nm in ytterbium

    NASA Astrophysics Data System (ADS)

    Hoyt, Chad; Barber, Zeb; Oates, Chris; Fortier, Tara; Diddams, Scott

    2005-05-01

    We report the first precision absolute frequency measurements of the highly forbidden (6s^2)^1S0<->(6s6p)^3P0 optical clock transition at 578.4 nm in two odd isotopes of ytterbium. Atoms are cooled to tens of microkelvins in two successive stages of laser cooling and magneto-optical trapping that use transitions at 398.9 nm and 555.8 nm, respectively. The resulting trapped atomic cloud is irradiated with excitation light at 578.4 nm and absorption is detected by monitoring trapped atom depletion. With the laser on resonance, we demonstrate trap depletions of more than 80 % relative to the off-resonance case. Absolute frequency measurements are made for ^171Yb (I=1/2) and ^173Yb (I=5/2) with an uncertainty of 4.4 kHz using a femtosecond-laser frequency comb calibrated by the NIST cesium fountain clock. The natural linewidth of these J=0 to J=0 transitions is ˜10 mHz, making them well-suited to support a new generation of optical atomic clocks based on confinement in an optical lattice. Lattice-based optical clocks have the potential to surpass the performance of the best current atomic clocks by orders of magnitude. The accurate ytterbium frequency knowledge presented here (nearly a million-fold reduction in uncertainty) will greatly expedite Doppler- and recoil-free lattice spectroscopy.

  13. Transitions of the type 2s-2p in fluorinelike and oxygenlike As, Se, Br, and Rb

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Seely, J. F.; Behring, W. E.; Richardson, M. C.; Goldsmith, S.

    1985-01-01

    Transitions of the type 2s-2p in the F I and O I isoelectronic sequences of arsenic, selenium, bromine, and rubidium have been identified in spectra from laser-produced plasmas. Wavelengths in the range 50 to 90 A were measured to an accuracy of 0.01 A or better. The wavelengths of the magnetic-dipole transitions within the ground configurations are predicted.

  14. Transitions 2s/2/ 2p/k/ - 2s 2p/k+1/ of the F I, O I, and N I isoelectronic sequences. [in laser plasma spectra

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Cowan, R. D.; Cohen, L.; Feldman, U.

    1974-01-01

    Transitions of the type 2s/2/ 2p/k/ - 2s 2p/k+1/ have been identified for the elements from titanium through nickel for ions of the fluorine, oxygen, and nitrogen isoelectronic sequences. Wavelengths, visual intensity estimates, and energies are given. The energy differences of levels of the ground configuration are compared with predictions based on semiempirical equations derived by Edlen. Some of the lines of these isoelectronic sequences should be strong lines in solar-flare spectra.

  15. Absolute frequency measurement of the 7s2 1S0-7s7p 1P1 transition in Ra225

    NASA Astrophysics Data System (ADS)

    Santra, B.; Dammalapati, U.; Groot, A.; Jungmann, K.; Willmann, L.

    2014-10-01

    Transition frequencies were determined for transitions in Ra in an atomic beam and for reference lines in Te2 molecules in a vapor cell. The absolute frequencies were calibrated against a GPS stabilized Rb clock by means of an optical frequency comb. The 7s21S0(F=1/2)-7s7p1P1(F =3/2) transition in Ra225 was determined to be 621042124(2)MHz. The measurements provide input for designing efficient and robust laser cooling of Ra atoms in preparation of a search for a permanent electric dipole moment in Ra isotopes.

  16. Theoretical transition probabilities between the lowest 2S, 2P and 2D states of Na, K, Rb and Cs

    NASA Technical Reports Server (NTRS)

    Langhoff, S. R.; Bauschlicher, C. W., Jr.; Partridge, H.

    1985-01-01

    Theoretical transition probabilities between the lowest 2S, 2P and 2D states of the alkali atoms Na through Cs have been computed using near Hartree-Fock quality Slater basis sets. The important core-valence correlation effects are incorporated explicitly by a configuration-interaction procedure. For Cs, the calculations were repeated using a Gaussian basis set so that relativistic effects could be incorporated through an effective core potential procedure. The best calculated electric quadrupole Einstein coefficients are Na(196.3/s), K(103.6/s), Rb(72.4/s) and Cs(19.7/s). Core-valence effects become increasingly important down the column, and reduce the quadrupole transition strengths to about the same degree as for the 2P-2S and 2D-2P dipole-allowed transitions. Relativistic effects increase the quadrupole moment of Cs, but less so than in Ba, presumably because the alkali 2D states are more diffuse.

  17. Towards a Mg Lattice Clock: Observation of the 1S0-3P0 Transition and Determination of the Magic Wavelength

    NASA Astrophysics Data System (ADS)

    Kulosa, A. P.; Fim, D.; Zipfel, K. H.; Rühmann, S.; Sauer, S.; Jha, N.; Gibble, K.; Ertmer, W.; Rasel, E. M.; Safronova, M. S.; Safronova, U. I.; Porsev, S. G.

    2015-12-01

    We optically excite the electronic state 3 s 3 p 3P0 in 24Mg atoms, laser cooled and trapped in a magic-wavelength lattice. An applied magnetic field enhances the coupling of the light to the otherwise strictly forbidden transition. We determine the magic wavelength, the quadratic magnetic Zeeman shift, and the transition frequency to be 468.46(21) nm, -206.6 (2.0 ) MHz /T2 , and 655 058 646 691(101) kHz, respectively. These are compared with theoretical predictions and results from complementary experiments. We also develop a high-precision relativistic structure model for magnesium, give an improved theoretical value for the blackbody radiation shift, and discuss a clock based on bosonic magnesium.

  18. Absolute frequency and isotope shift of the magnesium (3 s2) 1S0→(3 s 3 d ) 1D2 two-photon transition by direct frequency-comb spectroscopy

    NASA Astrophysics Data System (ADS)

    Peters, E.; Reinhardt, S.; Hänsch, Th. W.; Udem, Th.

    2015-12-01

    We use a picosecond frequency-doubled mode-locked titanium sapphire laser to generate a frequency comb at 431 nm in order to probe the (3 s2) 1S0 →(3 s 3 d ) 1D2 transition in atomic magnesium. Using a second, self-referenced femtosecond frequency comb, the absolute transition frequency and the 24Mg and 26Mg isotope shift is determined relative to a global-positioning-system-referenced hydrogen maser. Our result for the transition frequency of the main isotope 24Mg of 1 391 128 606.14 (12 ) MHz agrees with previous measurements and reduces its uncertainty by four orders of magnitude. For the isotope shift we find δ ν26 ,24=3915.13 (39 ) MHz. Accurate values for transition frequencies in Mg are relevant in astrophysics and to test atomic structure calculations.

  19. Absolute measurement of the 1S0 − 3P0 clock transition in neutral 88Sr over the 330 km-long stabilized fibre optic link

    PubMed Central

    Morzyński, Piotr; Bober, Marcin; Bartoszek-Bober, Dobrosława; Nawrocki, Jerzy; Krehlik, Przemysław; Śliwczyński, Łukasz; Lipiński, Marcin; Masłowski, Piotr; Cygan, Agata; Dunst, Piotr; Garus, Michał; Lisak, Daniel; Zachorowski, Jerzy; Gawlik, Wojciech; Radzewicz, Czesław; Ciuryło, Roman; Zawada, Michał

    2015-01-01

    We report a stability below 7 × 10−17 of two independent optical lattice clocks operating with bosonic 88Sr isotope. The value (429 228 066 418 008.3(1.9)syst (0.9)stat Hz) of the absolute frequency of the 1S0 – 3P0 transition was measured with an optical frequency comb referenced to the local representation of the UTC by the 330 km-long stabilized fibre optical link. The result was verified by series of measurements on two independent optical lattice clocks and agrees with recommendation of Bureau International des Poids et Mesures. PMID:26639347

  20. Electron excitation cross sections for the 2s(2)2p(3)4S(O) -- 2s(2)2p(3)2D(O) (forbidden) and 4S(O) -- 2s2p(4) 4P (resonance) transitions in O II

    NASA Technical Reports Server (NTRS)

    Zuo, M.; Smith, Steven J.; Chutjian, A.; Williams, I. D.; Tayal, S. S.; Mclaughlin, Brendan M.

    1995-01-01

    Experimental and theoretical excitation cross sections are reported for the first forbidden transition 4S(O) -- 2S(2)2p(3) 2D(O) (lambda-lambda 3726, 3729) and the first allowed (resonance) transition 4S(O) -- 2s2p(4) 4P(lambda-833) in O II. Use is made of electron energy loss and merged-beams methods. The electron energy range covered is 3.33 (threshold) to 15 eV for the S -- D transition, and 14.9 (threshold) to 40 eV for the S -- P transition. Care was taken to assess and minimize the metastable fraction of the O II beam. An electron mirror was designed and tested to reflect inelastically backscattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-matrix calculations. Calculations are also presented for the 4S(O) -- 2s(2)2p(3)2P(O) (lambda-2470) transition.

  1. Glass transition and fragility in the simple molecular glassformer CS2 from CS2-S2Cl2 solution studies

    NASA Astrophysics Data System (ADS)

    Zhao, Zuofeng; Huang, Wei; Richert, Ranko; Angell, C. Austen

    2010-04-01

    With an interest in finding the fragility for a simple, single component, molecular glassformer, we have determined the dielectric relaxation and glass transition behavior for a series of glasses in the CS2-S2Cl2 and CS2-toluene systems. Crystallization of CS2 can be completely avoided down to the composition 20 mol% second component, and the fragility proves almost independent of CS2 content in each system. Since the glass temperature Tg obtained from both thermal studies and from dielectric relaxation (using Tg,diel=Tτ =100 s) is quite linear over the whole composition range in each system, and since relaxation time data for pure CS2 fall on the same master plot when scaled by the linearly extrapolated Tg value, we deduce that pure CS2 has the same high fragility as the binary solutions. The value is m =86, as for ortho-terphenyl (OTP). Based on observations of independent studies for the vibrational density of states (VDoS) (of inherent structures for OTP and instantaneous, at-temperature structures for CS2), we attribute the high fragility to an excess vibrational heat capacity (defined by Cp (vib, excess)=dS(vib, excess)/d ln T) originating in the behavior of the low frequency modes of the VDoS (the boson peak modes). Both low frequency DoS and anharmonicity increase with increasing temperature, augmenting the configurational entropy drive to the top of the system energy landscape. The surprising implication is that fragility is determined in the vibrational, not configurational, manifold of microstates.

  2. Absolute frequency measurement of 1S0(F = 1/2)-3P0(F = 1/2) transition of 171Yb atoms in a one-dimensional optical lattice at KRISS

    NASA Astrophysics Data System (ADS)

    Park, Chang Yong; Yu, Dai-Hyuk; Lee, Won-Kyu; Eon Park, Sang; Kim, Eok Bong; Lee, Sun Kyung; Cho, Jun Woo; Yoon, Tai Hyun; Mun, Jongchul; Jong Park, Sung; Kwon, Taeg Yong; Lee, Sang-Bum

    2013-04-01

    We measured the absolute frequency of the optical clock transition 1S0(F = 1/2)-3P0(F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 863.5(8.1) Hz. The frequency was measured against Terrestrial Time (TT; the SI second on the geoid) using an optical frequency comb of which the frequency was phase-locked to an H-maser as a flywheel oscillator traceable to TT. The magic wavelength was also measured as 394 798.48(79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.

  3. Transition probabilities for the Au ((2)S, (2)D, and (2)P) with SiH(4) reaction.

    PubMed

    Pacheco-Sánchez, J H; Luna-García, H M; García-Cruz, L M; Novaro, O

    2010-01-28

    Transition probabilities on the interaction of the ground and the lowest excited states of gold Au ((2)S:5d(10)6s(1), (2)D:5d(9)6s(2), and (2)P:5d(10)6p(1)) with silane (SiH(4)) are studied through ab initio Hartree-Fock self-consistent field calculations, where the atom's core is represented by relativistic effective core potentials. These calculations are followed by a multiconfigurational self-consistent field study. The correlation energy is accounted for through extensive variational and perturbative second order multireference Moller-Plesset configuration interaction analysis of selected perturbations obtained by iterative process calculations using the CIPSI program package. It is found that the Au atom in the ((2)P:5d(10)6p(1)) state inserts in the Si-H bond. In this interaction its corresponding D (2)A(') potential energy surface is initially attractive and only becomes repulsive after encountering an avoided crossing with the initially repulsive C (2)A(') surface linked to the Au((2)D:5d(9)6s(2))-SiH(4) fragments. The A, B, and C (2)A(') curves derived from the Au((2)D:5d(9)6s(2)) atom interaction with silane are initially repulsive, each one of them showing two avoided crossings, while the A (2)A(') curve goes sharply downwards until it meets the X (2)A(') curve interacting adiabatically, which is linked with the Au((2)S:5d(10)6s(1))-SiH(4) moieties. The A (2)A(') curve becomes repulsive after the avoided crossing with the X (2)A('), curve. The lowest-lying X (2)A(') potential leads to the HAuSiH(3) X (2)A(') intermediate molecule. This intermediate molecule, diabatically correlated with the Au((2)P:5d(10)6p(1))+SiH(4) system which lies 3.34 kcal/mol above the ground state reactants, has been carefully characterized as have the dissociation channels leading to the AuH+SiH(3) and H+AuSiH(3) products. These products are reached from the HAuSiH(3) intermediate without any activation barrier. The Au-SiH(4) calculation results are successfully compared to

  4. Synthesis and spectroscopic characterization of some transition metal complexes of a new hexadentate N 2S 2O 2 Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Sarkar, Saikat; Dey, Kamalendu

    2005-11-01

    A novel interesting hexadentate dibasic N 2S 2O 2 donor Schiff base ligand, H4dcsalpte, was synthesized by the condensation of 3-formylsalicylic acid and 1,2-di( o-aminophenylthio)ethane and characterized. The reactions of the ligand with different metal(II/III)salts under varied reaction conditions afforded a series of metal complexes. The ligand, H4dcsalpte, behaves either as a dibasic or neutral hexadentate one, depending on the reaction conditions. Structural investigations on the ligand and their complexes have been made based on elemental analyses, molar conductance values, magnetic moment values, cryomagnetic and spectral (UV-vis, IR, 1H NMR, and Mössbauer) data. Based on magnetic susceptibility, Mössbauer and electronic spectral data the iron(III) complex [Fe III( H2dcsalpte)]ClO 4 ( 8), isolated in the present investigation, it is inferred that the spin states 5/2 and 1/2 are in equilibrium. Similarly a tri-iron(III) complex [Fe III3( H2dcsalpte)( H3dcsalpte)Cl 3]Cl 3 ( 7), isolated in this study, has been inferred to contain two iron(III) sites in tetrahedral environment and one in the octahedral environment. The aerial oxidation of an equimolar mixture of H4dcsalpte and Co(CH 3COO) 2·4H 2O in ethanol under reflux gave two products, [Co( H2dcsalpte)]CH 3COO ( 10) and [( Hbtcsaldm)Co( Hbvcsaldm)] ( 11), a cobalt(III) complex bound to two dissimilar tridentate NSO donor ligands formed as a result of the oxidative cleavage of the C sbnd S bond. In the complex 11, Hbtcsaldm stands for the dianion of the tridentate Schiff base ligand N-(2'-benzenethiol)-3-carboxysalicylaldimine and Hbvcsaldm stands for the mono anion of the tridentate Schiff base ligand N-(benzene-2'-S-vinyl)-3-carboxysalicylaldimine, both being formed as a result of the oxidative cleavage of H4dcsalpte.

  5. Precision frequency measurement of 1S0-3P1 intercombination lines of Sr isotopes

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Gao, Feng; Ye-Bing, Wang; Xiao, Tian; Jie, Ren; Ben-Quan, Lu; Qin-Fang, Xu; Yu-Lin, Xie; Hong, Chang

    2015-01-01

    We report on frequency measurement of the intercombination (5s2)1S0-(5s5p)3P1 transition of the four natural isotopes of strontium, including 88Sr (82.58%), 87Sr (7.0%), 86Sr (9.86%), and 84Sr (0.56%). A narrow-linewidth laser that is locked to an ultra-low expansion (ULE) optical cavity with a finesse of 12000 is evaluated at a linewidth of 200 Hz with a fractional frequency drift of 2.8×10-13 at an integration time of 1 s. The fluorescence collector and detector are specially designed, based on a thermal atomic beam. Using a double-pass acousto-optic modulator (AOM) combined with a fiber and laser power stabilization configuration to detune the laser frequency enables high signal-to-noise ratios and precision saturated spectra to be obtained for the six transition lines, which allows us to determine the transition frequency precisely. The optical frequency is measured using an optical frequency synthesizer referenced to an H maser. Both the statistical values and the final values, including the corrections and uncertainties, are derived for a comparison with the values given in other works. Project supported by the National Natural Science Foundation of China (Grant No. 61127901) and the Key Project of the Chinese Academy of Sciences (Grant No. KJZD-EW-W02).

  6. 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.

  7. Energies and E1, M1, E2, M2 transition rates for states of the 2s{sup 2}2p, 2s2p{sup 2}, and 2p{sup 3} configurations in boron-like ions between N III and Zn XXVI

    SciTech Connect

    Rynkun, P.; Joensson, P.; Gaigalas, G.; Froese Fischer, C.

    2012-07-15

    Energies, E1, M1, E2, M2 transition rates, line strengths, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the (1s{sup 2})2s{sup 2}2p, 2s2p{sup 2}, and 2p{sup 3} configurations in all boron-like ions between N III and Zn XXVI. Valence, core-valence, and core-core correlation effects were accounted for through single-double multireference (SD-MR) expansions to increasing sets of active orbitals.

  8. Energies and E1, M1, E2, and M2 transition rates for states of the 2s22p3, 2s2p4, and 2p5 configurations in nitrogen-like ions between F III and Kr XXX

    NASA Astrophysics Data System (ADS)

    Rynkun, P.; Jönsson, P.; Gaigalas, G.; Froese Fischer, C.

    2014-03-01

    Based on relativistic wavefunctions from multiconfiguration Dirac-Hartree-Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s2)2s22p3,2s2p4, and 2p5 configurations in all nitrogen-like ions between F III and Kr XXX. The wavefunction expansions include valence, core-valence, and core-core correlation effects through single-double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300-600 cm-1 for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A&A 385 (2002) 716].

  9. 1S0 nucleon-nucleon scattering in the modified Weinberg approach

    NASA Astrophysics Data System (ADS)

    Epelbaum, E.; Gasparyan, A. M.; Gegelia, J.; Krebs, H.

    2015-06-01

    Nucleon-nucleon scattering in the 1 S 0 partial wave is considered in chiral effective field theory within the renormalizable formulation of a previous work (Phys. Lett. B 716, 338 (2012)) beyond the leading-order approximation. By applying subtractive renormalization, the subleading contact interaction in this channel is taken into account non-perturbatively. For a proper choice of renormalization conditions, the predicted energy dependence of the phase shift and the coefficients in the effective range expansion are found to be in a good agreement with the results of the Nijmegen partial wave analysis.

  10. Quantum chaos in ultracold collisions between Yb(1S0) and Yb(3P2)

    NASA Astrophysics Data System (ADS)

    Green, Dermot G.; Vaillant, Christophe L.; Frye, Matthew D.; Morita, Masato; Hutson, Jeremy M.

    2016-02-01

    We calculate and analyze Feshbach resonance spectra for ultracold Yb (1S0) +Yb (3P2) collisions as a function of an interatomic potential scaling factor λ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in λ , but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances with respect to magnetic field in the experimentally accessible range of 400 to 2000 G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.

  11. Energies and E1, M1, E2, and M2 transition rates for states of the 2s{sup 2}2p{sup 3}, 2s2p{sup 4}, and 2p{sup 5} configurations in nitrogen-like ions between F III and Kr XXX

    SciTech Connect

    Rynkun, P.; Jönsson, P.; Gaigalas, G.; Froese Fischer, C.

    2014-03-15

    Based on relativistic wavefunctions from multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s{sup 2})2s{sup 2}2p{sup 3},2s2p{sup 4}, and 2p{sup 5} configurations in all nitrogen-like ions between F III and Kr XXX. The wavefunction expansions include valence, core–valence, and core–core correlation effects through single–double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300–600 cm{sup −1} for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A and A 385 (2002) 716].

  12. Reference free, high-precision measurements of transition energies in few electron argon ions

    NASA Astrophysics Data System (ADS)

    Szabo, Csilla I.; Amaro, Pedro; Guerra, Mauro; Schlesser, Sophie; Gumberidze, Alexander; Santos, José Paulo; Indelicato, Paul

    2013-04-01

    The use of a vacuum double crystal spectrometer, coupled to an electron-cyclotron resonance ion source (ECRIS), allows to measure low-energy x-ray transitions energies in highly-charged ions with accuracies of the order of a few parts per million. We have used this installation to measure the 1s2p 1 P1 → 1s2 1 S0 diagram line and the 1s2s 3 S1 → 1s2 1 S0 forbidden M1 transition energies in helium-like argon, the 1s2s2p 2 Pj → 1s2 2s 2 S1/2 transitions in lithium-like argon and the 1s2s2 2p 1 P1 → 1s2 2s2 1 S0 transition in beryllium-like argon. These transition measurements have accuracies between 2 and 4 ppm depending on the line intensity. Thanks to the excellent agreement between the simulations and the measurements, we were also able to measure the transition width of all the allowed transitions. The results are compared to recent QED and relativistic many-body calculations.

  13. The PI2S2 project: grid and new challenges .

    NASA Astrophysics Data System (ADS)

    Becciani, U.

    The new grid e-Infrastructure in Sicily is offering new perspectives and important resources for both scientific and industrial application in the National context. This paper shows the infrastructure of the Cometa Consortium built with the PI2S2 project, the current status of the project and the new challenges, mainly in the HPC area, that the project is carrying out.

  14. Effects of tensor couplings of ω and ρ mesons on 1S0 nucleon superfluidity in neutron star matter

    NASA Astrophysics Data System (ADS)

    Huang, Xiu-Lin; Xu, Yan; Liu, Cheng-Zhi; Liu, Guang-Zhou

    2016-03-01

    The 1S 0 nucleon superfluidity in neutron star matter was investigated in the framework of relativistic σ-ω-π-ρ model with the tensor couplings of ω and ρ mesons using the relativistic Hartree-Fock (RHF) approximation. It was found that the tensor couplings of ω and ρ mesons lead to a clear growth of the 1S 0 neutron pairing gap in the density range where there exists 1S 0 neutron superfluidity. The 1S 0 pairing gap of proton with the tensor couplings of ω and ρ mesons in the density range of ρB = 0.0-0.079fm-3 is lower and then in the density range of ρB = 0.079-0.383fm-3 higher than the corresponding value without the tensor couplings of ω and ρ mesons. Our results provide a basic to understand the influence of the tensor couplings of ω and ρ mesons on the cooling properties of neutron star.

  15. The Cometa Consortium and the PI2S2 project .

    NASA Astrophysics Data System (ADS)

    Becciani, U.

    The new grid e-Infrastructure in Sicily is offering new perspectives and important resources and starts to give new great opportunity for research using the HPC resources. We will show the infrastructure of the Cometa Consortium, the main activities of the PI2S2 project and the new challenges, mainly in the HPC area, that the project is carrying out. A simple but useful procedure for running HPC is also described.

  16. Interruption of electronically excited Xe dimer formation by the photoassociation of Xe(6s[3/2]2)-Xe(5p6 1S0) thermal collision pairs

    NASA Astrophysics Data System (ADS)

    Galvin, T. C.; Wagner, C. J.; Eden, J. G.

    2016-06-01

    The diatomic collisional intermediate responsible for the formation of an electronically excited molecule by teratomic recombination has been observed in both the spectral and temporal domains by laser spectroscopy. We report experiments demonstrating thermal Xe(6s[3/2]2)-Xe(5p6 1S0) atomic collision pairs to be the immediate precursor to the formation of Xe 2∗ ( a 3 Σu + , A 1 Σu +) by the three body process: Xe∗(6s) + 2Xe ⟶ Xe 2∗ + Xe, where the asterisk denotes an excited electronic state. Photoassociating Xe(6s)-Xe atomic pairs by free ⟵ free transitions of the collision complex interrupts the production of the electronically excited Xe dimer, thereby suppressing Xe2 spontaneous emission in the vacuum ultraviolet (VUV, λ ˜ 172 nm, A 1 Σu + → X 1 Σg +). Intercepting Xe(6s)-Xe pairs before the complex is stabilized by the arrival of the third atom in the teratomic collision process selectively depletes the pair population in a specific Franck-Condon region determined by the probe laser wavelength (λ). Measurements of the variation of VUV emission suppression with λ provide a spectral signature of the [Xe(6s[3/2]2) - Xe(1S0)]∗ complex and map the probe laser wavelength onto the thermal energy (ɛ″) of the incoming collision pairs.

  17. The Neutron-Neutron ^1S0 Scattering Length via the Reaction π^-d→γ nn

    NASA Astrophysics Data System (ADS)

    Saliba, M. A.; Measday, D. F.; Stocki, T. J.; Christy, M. E.; Doyle, B. C.; Gorringe, T. P.; Jiang, C.; Kovash, M. A.; Liu, K.; Bassalleck, B.; Stasko, J.; Wolfe, D.; Korkmaz, E.; Opper, A.; Sim, K.; Fischer, H.; Ottewell, D.

    1997-10-01

    A measurement of the ^1S0 neutron-neutron scattering length, a quantity crucial to the discussion of charge symmetry breaking in the NN interaction, has been carried out at TRIUMF by studying the shape of the photon energy spectrum from the reaction π^-d→γ nn in the region near the endpoint. A 40.5 MeV pion beam was degraded and stopped in a liquid deuterium target and all three final state particles from the reaction were detected in triple coincidence. The experimental photon energy spectrum was reconstructed from the measured momenta of the two neutrons, and contains 133,000 counts in the top 450 keV region near the endpoint. The experimental resolution was taken into account using Monte Carlo techniques. The data were analyzed using a model of this reaction based on a half off-shell NN T matrix and the elementary γπ operator due to Lee and Nozawa.

  18. Electron Excitation Cross Sections for the 2s(sup 2)2p(sup 3) (sup 4)S -> 2s(sup 2)2p(sup 3) (sup 2d) ->2s2p(sup 4) (sup 4p) (Resonance) Transitions in Oil

    NASA Technical Reports Server (NTRS)

    Zuo, M.; Smith, S.; Chutjian, A.; Williams, I.; Tayal, S.; McLaughlin, B.

    1994-01-01

    Experimental and theoretical excitation cross sections are reported for the first forbidden transition xxx and the first allowed (resonance) transition xxx in OII. Use is made of electron-energy loss and merged beams methods. The electron energy range covered is 3.33 eV (threshold) to 15 eV for the S->D transition, and 14.9 eV (threshold) to 40 eV for the S->P transition. Care was taken to assess and minimize the metastable fraction of the OII beam. An electron mirror was designed and tested to reflect inelastically back-scattered electrons into the forward direction to account for the full range of polar scattering angles. Comparisons are made between present experiments and 11-state R-Matrix calculations. Calculations are also presented for the xxx transition.

  19. Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions

    SciTech Connect

    Cheng, K T; Chen, M H; Johnson, W R

    2008-03-13

    The hyperfine-induced 2s2p {sup 3}P{sub 0}-2s{sup 2} {sup 1}S{sub 0} transition rate for Be-like {sup 47}Ti{sup 18+} was recently measured in a storage-ring experiment by Schippers et al. [Phys. Rev. Lett. 98, 033001 (2007)]. The measured value of 0.56(3) s{sup -1} is almost 60% larger than the theoretical value of 0.356 s{sup -1} from a multiconfiguration Dirac-Fock calculation by Marques et al. [Phys. Rev. A 47, 929 (1993)]. In this work, we use a large-scale relativistic configuration-interaction method to calculate these hyperfine-induced rates for ions with Z = 6-92. Coherent hyperfine-quenching effects between the 2s2p {sup 1,3}P{sub 1} states are included in a perturbative as well as a radiation damping approach. Contrary to the claims of Marques et al., contributions from the {sup 1}P{sub 1} state are substantial and lead to a hyperfine-induced rate of 0.67 s{sup -1}, in better agreement with, though larger than, the measured value.

  20. Spectroscopic and Redox Studies of Valence-Delocalized [Fe2S2]+ Centers in Thioredoxin-Like Ferredoxins

    PubMed Central

    Subramanian, Sowmya; Duin, Evert C.; Fawcett, Sarah E. J.; Armstrong, Fraser A.; Meyer, Jacques; Johnson, Michael K.

    2015-01-01

    Reduced forms of the C56S and C60S variants of the thioredoxin-like Clostridium pasteurianum [Fe2S2] ferredoxin (CpFd) provide the only known examples of valence-delocalized [Fe2S2]+ clusters, which constitute a fundamental building block of all higher nuclearity Fe-S clusters. In this work, we have revisited earlier work on the CpFd variants and carried out redox and spectroscopic studies on the [Fe2S2]2+,+ centers in wild-type and equivalent variants of the highly homologous and structurally characterized Aquifex aeolicus ferredoxin 4 (AaeFd4) using EPR, UV-visible-NIR absorption, CD and variable-temperature MCD, and protein-film electrochemistry. The results indicate that the [Fe2S2]+ centers in the equivalent AaeFd4 and CpFd variants reversibly interconvert between similar valence-localized S = 1/2 and valence-delocalized S = 9/2 forms as a function of pH, with pKa values in the range 8.3-9.0, due to protonation of the coordinated serinate residue. However, freezing high-pH samples results in partial or full conversion from valence-delocalized S = 9/2 to valence-localized S = 1/2 [Fe2S2]+ clusters. MCD saturation magnetization data for valence-delocalized S = 9/2 [Fe2S2]+ centers facilitated determination of transition polarizations and thereby assignments of low-energy MCD bands associated with the Fe−Fe interaction. The assignments provide experimental assessment of the double exchange parameter, B, for valence-delocalized [Fe2S2]+ centers and demonstrate that variable-temperature MCD spectroscopy provides a means of detecting and investigating the properties of valence-delocalized S = 9/2 [Fe2S2]+ fragments in higher nuclearity Fe-S clusters. The origin of valence delocalization in thioredoxin-like ferredoxin Cys-to-Ser variants and Fe-S clusters in general is discussed in light of these results. PMID:25790339

  1. Spectroscopic and redox studies of valence-delocalized [Fe2S2](+) centers in thioredoxin-like ferredoxins.

    PubMed

    Subramanian, Sowmya; Duin, Evert C; Fawcett, Sarah E J; Armstrong, Fraser A; Meyer, Jacques; Johnson, Michael K

    2015-04-01

    Reduced forms of the C56S and C60S variants of the thioredoxin-like Clostridium pasteurianum [Fe2S2] ferredoxin (CpFd) provide the only known examples of valence-delocalized [Fe2S2](+) clusters, which constitute a fundamental building block of all higher nuclearity Fe-S clusters. In this work, we have revisited earlier work on the CpFd variants and carried out redox and spectroscopic studies on the [Fe2S2](2+,+) centers in wild-type and equivalent variants of the highly homologous and structurally characterized Aquifex aeolicus ferredoxin 4 (AaeFd4) using EPR, UV-visible-NIR absorption, CD and variable-temperature MCD, and protein-film electrochemistry. The results indicate that the [Fe2S2](+) centers in the equivalent AaeFd4 and CpFd variants reversibly interconvert between similar valence-localized S = 1/2 and valence-delocalized S = 9/2 forms as a function of pH, with pKa values in the range 8.3-9.0, because of protonation of the coordinated serinate residue. However, freezing high-pH samples results in partial or full conversion from valence-delocalized S = 9/2 to valence-localized S = 1/2 [Fe2S2](+) clusters. MCD saturation magnetization data for valence-delocalized S = 9/2 [Fe2S2](+) centers facilitated determination of transition polarizations and thereby assignments of low-energy MCD bands associated with the Fe-Fe interaction. The assignments provide experimental assessment of the double exchange parameter, B, for valence-delocalized [Fe2S2](+) centers and demonstrate that variable-temperature MCD spectroscopy provides a means of detecting and investigating the properties of valence-delocalized S = 9/2 [Fe2S2](+) fragments in higher nuclearity Fe-S clusters. The origin of valence delocalization in thioredoxin-like ferredoxin Cys-to-Ser variants and Fe-S clusters in general is discussed in light of these results. PMID:25790339

  2. Determination of hyperfine-induced transition rates from observations of a planetary nebula.

    PubMed

    Brage, Tomas; Judge, Philip G; Proffitt, Charles R

    2002-12-31

    Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p 3P(o)(0)-->2s2 1S0 in the berylliumlike emission line spectrum of N IV at 1487.89 A. A nebular model allows us to confirm a transition rate of 4x10(-4) sec(-1)+/-33% for this line. The measurement represents the first independent confirmation of the transition rate of hyperfine-induced lines in low ionization stages, and it provides support for the techniques used to compute these transitions for the determination of very low densities and isotope ratios. PMID:12513129

  3. Electron excitation cross sections for the 2s^2 2p ^2p^o-2s2p^2 ^4p and 2s2p^2 ^2D transitions in O^3+

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Lozano, J. A.; Tayal, S. S.; Chutjian, A.

    2003-01-01

    Comparison is made with results of new calculations in a 25-state R-matrix theory and with results in a previous eight-state R-matrix calculation. The presence of rich resonance structure is confirmed in both experiment and theory.

  4. Transient existence of crystalline lithium disulfide Li2S2 in a lithium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Paolella, Andrea; Zhu, Wen; Marceau, Hugues; Kim, Chi-su; Feng, Zimin; Liu, Dongqiang; Gagnon, Catherine; Trottier, Julie; Abdelbast, Guerfi; Hovington, Pierre; Vijh, Ashok; Demopoulos, George P.; Armand, Michel; Zaghib, Karim

    2016-09-01

    Crystalline lithium disulfide (Li2S2) is identified, for the first time, as a transient species in the lithium-sulfur cell, by using an operando X-ray diffraction (XRD) technique. The observed XRD pattern precisely matches with the predicted pattern based on the density function theory. The formation of Li2S2 crystals is repetitively found in the highly concentrated (7 M Li+) electrolyte at high voltage region (>2 V) near the end of the first charge cycle and before the end of the second discharge cycle. These conditions indicate that crystalline Li2S2 exists in the non-equilibrium regime. The formation of crystalline Li2S2 under only the specified conditions suggests that it is not formed as an intermediate discharge product, contrary to what is generally believed, but as a transient species by the disproportionation reaction from higher order polysulfides which is facilitated by the "solvent-in-salt" conditions.

  5. Measurement of the 1s2s 1S0-1s2p 3P1 intercombination interval in helium-like silicon.

    PubMed

    Redshaw, M; Myers, E G

    2002-01-14

    Using Doppler-tuned fast-beam laser spectroscopy the 1s2s 1S0-1s2p 3P1 intercombination interval in 28Si12+ has been measured to be 7230.5(2) cm(-1). The experiment made use of a single-frequency Nd:YAG (1.319 microm) laser and a high-finesse optical buildup cavity. The result provides a precision test of modern relativistic and QED atomic theory. PMID:11801009

  6. Improved measurement of the 1s2s 1S0-1s2p 3P1 interval in heliumlike silicon.

    PubMed

    DeVore, Thomas R; Crosby, David N; Myers, Edmund G

    2008-06-20

    Using colinear fast-beam laser spectroscopy with copropagating and counter-propagating beams we have measured the 1s2s 1S0-1s2p 3P1 intercombination interval in 28Si12+ with the result 7230.585(6) cm{-1}. The experiment made use of a dual-wavelength, high-finesse, power build-up cavity excited by single-frequency lasers at 1319 and 1450 nm. The result will provide a precision test of ab initio relativistic many-body atomic theory at moderate Z. PMID:18643579

  7. Strong laser-induced coupling between autoionizing states: the case of the four-photon-excited 3p2 1S0 state of magnesium

    NASA Astrophysics Data System (ADS)

    Dimitriou, A.; Cohen, S.; Lyras, A.; Liontos, I.

    2012-10-01

    We investigate the interaction of ground-state Mg atoms with tuneable laser radiation of ˜5 ns duration and moderate intensity (≤1012 W cm-2), capable of exciting the 3p2 1S0 autoionizing state by four photons. For the corresponding photon energy range, this level is strongly one-photon coupled both with bound (third photon) and, primarily, a multitude of other autoionizing states (fifth photon). The coupling is strong enough to induce the absorption of up to six photons before the atom is ionized, creating thus population into the first excited 3pj Mg+ levels which subsequently decay radiatively to the 3s1/2 ionic ground state. The earlier studies devoted to this excitation scheme were thorough but partial. Particularly, the issues concerning the five-photon excited levels were not addressed. In this work, the examined wavelength range is greatly extended to include these states. Moreover, the interaction is characterized in more detail by employing an array of experimental techniques, namely Mg+ ion and photoelectron spectroscopy (including photoelectron angular distributions (PADs) from four- and five-photon ionization) as well as fluorescence spectroscopy where the 3pj→3s1/2 decay is monitored. The experimental data show that most of these five-photon excited levels undergo blue ac Stark shifts which are occasionally nonlinear with respect to the laser intensity and comparable to or even larger in magnitude than the large redshift of the 3p2 1S0 state itself. Finally, for the latter state, the wavelength dependence of four-photon PAD measurements is suggestive of a situation reminiscent of an ac Stark splitting picture.

  8. Measurement of the transition probability of the C III 190.9 nanometer intersystem line

    NASA Technical Reports Server (NTRS)

    Kwong, Victor H. S.; Fang, Z.; Gibbons, T. T.; Parkinson, W. H.; Smith, Peter L.

    1993-01-01

    A radio-frequency ion trap has been used to store C(2+) ions created by electron bombardment of CO. The transition probability for the 2s2p 3Po1-2s2 1S0 intersystem line of C m has been measured by recording the radiative decay at 190.9 nm. The measured A-value is 121 +/- 7/s and agrees, within mutual uncertainty limits, with that of Laughlin et al. (1978), but is 20 percent larger than that of Nussbaumer and Storey (1978). The effective collision mixing rate coefficient among the fine structure levels of 3Po and the combined quenching and charge transfer rate coefficients out of the 3Po1 level with the CO source gas have also been measured.

  9. M2, S2, K1 models of the global ocean tide

    NASA Technical Reports Server (NTRS)

    Parke, M. E.; Hendershott, M. C.

    1979-01-01

    Ocean tidal signals appear in many geophysical measurements. Geophysicists need realistic tidal models to aid in interpretation of their data. Because of the closeness to resonance of dissipationless ocean tides, it is difficult for numerical models to correctly represent the actual open ocean tide. As an approximate solution to this problem, test functions derived by solving Laplace's Tidal Equations with ocean loading and self gravitation are used as a basis for least squares dynamic interpolation of coastal and island tidal data for the constituents M2, S2, and Kl. The resulting representations of the global tide are stable over at least a ?5% variation in the mean depth of the model basin, and they conserve mass. Maps of the geocentric tide, the induced free space potential, the induced vertical component of the solid earth tide, and the induced vertical component of the gravitational field for each contituent are presented.

  10. Rotationally resolved S1<--S0 electronic spectra of fluorene, carbazole, and dibenzofuran: Evidence for Herzberg-Teller coupling with the S2 state

    NASA Astrophysics Data System (ADS)

    Yi, John T.; Alvarez-Valtierra, Leonardo; Pratt, David W.

    2006-06-01

    Rotationally resolved fluorescence excitation spectra of the S1←S0 origin bands and higher vibronic bands of fluorene (FLU), carbazole (CAR), and dibenzofuran (DBF) have been observed and assigned. Analyses of these data show that replacement of the CH2 group in FLU with a NH group in CAR and an O atom in DBF produces only localized changes in structure, in the ground state. But the three molecules exhibit different changes in geometry when they are excited by light. The S1 states of the three molecules also are electronically very different. The S1←S0 transition moments of CAR and DBF are parallel to the C2 symmetry axis whereas the corresponding transition moment in FLU is perpendicular to this axis. Herzberg-Teller coupling involving the S2 state also has been observed in the spectra of higher vibronic bands of CAR and DBF. Possible reasons for these behaviors are discussed.

  11. Vibration-rotation line shifts for 1 sigma g + H2/V,J/-1S/0/ He computed via close coupling - Temperature dependence

    NASA Technical Reports Server (NTRS)

    Hahne, G. E.; Chackerian, C., Jr.

    1980-01-01

    The density shifting of vibration-rotation transitions of H2 perturbed by He was computed (as a function of temperature) with no adjustable parameters. The calculation was carried out using the framework of the impact theory of Baranger with S-matrix elements obtained via close coupling calculations which incorporated the ab initio H2-H2 system potential of Tsapline et al.(1977). Vibrational and rotational inelasticity were neglected in the calculations; nevertheless good agreement with experimental data was obtained, up to moderate temperatures, for the density shift. A much poorer comparison was obtained for the density broadening.

  12. Measurement of the metastable lifetime for the 2s^2 2p^2 ^1So level in O^2+

    NASA Technical Reports Server (NTRS)

    Smith, S. J.; Cadez, I.; Chutjian, A.; Niimura, M.

    2004-01-01

    The radiative lifetime of the 1S0 level was found to be 540 +/- 27 ms. This is in good agreement with a previous measurement and with a number of theoretical calculations. Metastable lifetimes, when combined with collisional excitation rates, can provide a diagnostic for electron density Ne in a stellar or solar plasma.

  13. Isovector spin-singlet (T = 1, S = 0) and isoscalar spin-triplet (T = 0, S = 1) pairing interactions and spin-isospin response

    NASA Astrophysics Data System (ADS)

    Sagawa, H.; Bai, C. L.; Colò, G.

    2016-08-01

    We review several experimental and theoretical advances that emphasize common aspects of the study of spin-singlet, T = 1, and spin-triplet, T = 0, pairing correlations in nuclei. We first discuss various empirical evidence of the special role played by the T = 1 pairing interaction. In particular, we show the peculiar features of the nuclear pairing interaction in the low-density regime, and possible outcomes such as the BCS–BEC crossover in nuclear matter and, in an analogous way, in loosely bound nuclei. We then move to the competition between T = 1 and T = 0 pairing correlations. The effect of such competition on the low-lying spectra is studied in N = Z odd-odd nuclei by using a three-body model; in this case, it is shown that the inversion of the {J}π ={0}+ and {J}π ={1}+ states near the ground state, and the strong magnetic dipole transitions between them, can be considered as a clear manifestation of strong T = 0 pairing correlations in these nuclei. The effect of T = 0 pairing correlations is also quite evident if one studies charge-changing transitions. The Gamow–Teller (GT) states in N=Z+2 nuclei are studied here by using self-consistent Hartree–Fock–Bogoliubov (HFB) plus quasiparticle random-phase approximation calculations in which the T = 0 pairing interaction is taken into account. Strong GT states are found, near the ground state of daughter nuclei; these are compared with available experimental data from charge-exchange reactions, and such comparison can pinpoint the value of the strength of the T = 0 interaction. Pair transfer reactions are eventually discussed. While two-neutron transfer has long been proposed as a tool to measure the T = 1 superfluidity in the nuclear ground states, the study of deuteron transfer is still in its infancy, despite its potential interest for revealing effects coming from both T = 1 and T = 0 interactions. We also point out that the reaction mechanism may mask the strong pair transfer amplitudes predicted

  14. Kermesite, Sb2S2O: crystal structure revision and order-disorder interpretation.

    PubMed

    Hybler, Jiří; Durovič, Slavomil

    2013-12-01

    Kermesite, Sb2S2O, is a desymmetrized order-disorder (OD) structure of layers. Two data sets were recorded using twinned crystals from Pezinok, Slovakia (named as Pz21, Pz24). The primitive unit cell is triclinic, P1, Z = 4, cell parameters are a = 8.1416 (3), b = 10.6968 (3), c = 5.7835 (2) Å, α = 102.758 (3), β = 110.657 (3), γ = 101.020 (3)°, R(obs) = 0.0243 (Pz21), and a = 8.1372 (2), b = 10.6969 (2), c = 5.7840 (1) Å, α = 102.787 (2), β = 110.606 (2), γ = 100.983 (2)°, R(obs) = 0.0321 (Pz24). The structure can also be described in the non-standard pseudo-monoclinic octuple (Z = 32), F-centered (Kupčík) cell with extra points in 1/4,1/4,0; 1/4,3/4,1/2; 3/4,1/4,1/2; 3/4,3/4,0, with parameters a = 21.6466 (9), b = 8.1416 (3), c = 20.3824 (9) Å, α = 90.079 (4), β = 101.985 (5), γ = 89.948 (4)° (Pz21), and a = 21.6558 (5), b = 8.1372 (2), c = 20.3859 (8) Å, α = 90.028 (3), β = 101.994 (3), γ = 89.986 (2)° (Pz24). The structure is built of layers parallel to the bc plane, stacked along the a vector of the octuple cell, composed of ribbons parallel to the b vector: (i) ribbon of two strips of SbO5 flattened quadrangular pyramids, sharing apical edges; (ii) ribbon of edge-sharing corrugated lozenges SbO3S. Basal S atoms of pyramids share corners of lozenges. Sb atoms are displaced out of coordination polyhedra into the inter-layer space. The OD layer comprises adjacent halves of the structure building layers. The layer group is A(1)2/m1, the protocell is defined by b, c, (a/4)sin β. The MDO1 (4A) polytype is generated by repetition of the t(1,1/4,0) [or alternatively t(1,-1/4,0)] translation. The co-existence of two kinds of domains give rise to the twinning. The twin operation is 2[010], twin index 2. The total continuation of [. a2 .] generates the MDO2 (2M) polytype, space group A12/a1. Simulated and real diffraction patterns are presented. The important values (edges, angles) and

  15. Structure and magnetic properties of flux grown single crystals of Co3-xFexSn2S2 shandites

    NASA Astrophysics Data System (ADS)

    Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

    2016-01-01

    We report a successful single crystal growth of the shandite-type half-metallic ferromagnet Co3Sn2S2, and its Fe-substituted compounds, Co3-xFexSn2S2, by employing the flux method. Although Fe3Sn2S2 is unstable phase, we found that using the self Sn flux enables us to obtain single phase crystals up to x=0.53. The chemical composition of the grown plate-shaped single crystals was examined using wavelength-dispersive X-ray spectroscopy. The shandite structure with R 3 ̅m symmetry was confirmed by powder X-ray diffraction and the crystal structure parameters were refined using the Rietveld method. Magnetization measurements show suppression of the ferromagnetic order upon Fe-substitution, as well as in other substituted systems such as In- and Ni-substituted Co3Sn2S2. The almost identical magnetic phase diagrams of the Fe- and In-substituted compounds indicate that the electron number is dominantly significant to the magnetism in the Co-based shandite.

  16. Density functional theory calculations on the active site of biotin synthase: mechanism of S transfer from the Fe(2)S(2) cluster and the role of 1st and 2nd sphere residues.

    PubMed

    Rana, Atanu; Dey, Subal; Agrawal, Amita; Dey, Abhishek

    2015-10-01

    Density functional theory (DFT) calculations are performed on the active site of biotin synthase (BS) to investigate the sulfur transfer from the Fe(2)S(2) cluster to dethiobiotin (DTB). The active site is modeled to include both the 1st and 2nd sphere residues. Molecular orbital theory considerations and calculation on smaller models indicate that only an S atom (not S²⁻) transfer from an oxidized Fe(2)S(2) cluster leads to the formation of biotin from the DTB using two adenosyl radicals generated from S-adenosyl-L-methionine. The calculations on larger protein active site model indicate that a 9-monothiobiotin bound reduced cluster should be an intermediate during the S atom insertion from the Fe(2)S(2) cluster consistent with experimental data. The Arg260 bound to Fe1, being a weaker donor than cysteine bound to Fe(2), determines the geometry and the electronic structure of this intermediate. The formation of this intermediate containing the C9-S bond is estimated to have a ΔG(≠) of 17.1 kcal/mol while its decay by the formation of the 2nd C6-S bond is calculated to have a ΔG(≠) of 29.8 kcal/mol, i.e. the 2nd C-S bond formation is calculated to be the rate determining step in the cycle and it leads to the decay of the Fe(2)S(2) cluster. Significant configuration interaction (CI), present in these transition states, helps lower the barrier of these reactions by ~30-25 kcal/mol relative to a hypothetical outer-sphere reaction. The conserved Phe285 residue near the Fe(2)S(2) active site determines the stereo selectivity at the C6 center of this radical coupling reaction. Reaction mechanism of BS investigated using DFT calculations. Strong CI and the Phe285 residue control the kinetic rate and stereochemistry of the product. PMID:26369537

  17. Optical response of the Cu2 S2 diamond core in Cu2II(NGuaS)2 Cl2.

    PubMed

    Witte, Matthias; Grimm-Lebsanft, Benjamin; Goos, Arne; Binder, Stephan; Rübhausen, Michael; Bernard, Martin; Neuba, Adam; Gorelsky, Serge; Gerstmann, Uwe; Henkel, Gerald; Gero Schmidt, Wolf; Herres-Pawlis, Sonja

    2016-09-15

    Density functional theory (DFT) and time-dependent DFT calculations are presented for the dicopper thiolate complex Cu2 (NGuaS)2 Cl2 [NGuaS=2-(1,1,3,3-tetramethylguanidino) benzenethiolate] with a special focus on the bonding mechanism of the Cu2 S2 Cl2 core and the spectroscopic response. This complex is relevant for the understanding of dicopper redox centers, for example, the CuA center. Its UV/Vis absorption is theoretically studied and found to be similar to other structural CuA models. The spectrum can be roughly divided in the known regions of metal d-d absorptions and metal to ligand charge transfer regions. Nevertheless the chloride ions play an important role as electron donors, with the thiolate groups as electron acceptors. The bonding mechanism is dissected by means of charge decomposition analysis which reveals the large covalency of the Cu2 S2 diamond core mediated between Cu dz2 and S-S π and π* orbitals forming Cu-S σ bonds. Measured resonant Raman spectra are shown for 360- and 720-nm excitation wavelength and interpreted using the calculated vibrational eigenmodes and frequencies. The calculations help to rationalize the varying resonant behavior at different optical excitations. Especially the phenylene rings are only resonant for 720 nm. © 2016 Wiley Periodicals, Inc. PMID:27362786

  18. N2S2 and N4S4 precursors to PS2 macrocycles and cyclic amidinium salts.

    PubMed

    Cox, Katrina; Kariuki, Benson M; Smyth, Alexander; Newman, Paul D

    2016-05-28

    The cyclo-condensation of 1R,2R-diaminocyclohexane with 2,2'-(ethane-1,2-diyldisulfanediyl)dibenzaldehyde gave the 1 : 1 addition compound chxn-(im)N2S2 in high yield. When the same condensation reaction was performed with 1R,3S-diamino-1,7,7-trimethylcyclopentane as the diamine, the 2 : 2 addition compound tmcp-(im)N4S4 was obtained selectively. Reduction of the diimines gave the saturated analogues chxn-N2S2 (1) and tmcp-N4S4 (3) the former of which could be phosphorylated with PhP(NMe2)2 to give the novel 13-membered macrocycle chxn-PS2, 2. Introduction of the phenylphosphine function proved stereoselective with a preference for the N(R)/N(S) configuration at the nitrogen atoms. The coordination chemistry of the novel phosphine has been explored with Cu(i) and Mo(0) through formation of the complexes Cu(2)I, 4, and Mo(CO)3(2), 5. Extension of the phosphorylation chemistry to tmcp-N4S4 (3) proved unsuccessful but ring closure reactions of both 1 and 3 with triethylorthoformate gave cyclic amidinium salts which are potential precursors to macrocyclic N-heterocyclic carbenes. PMID:27112102

  19. Nbody Simulations and Weak Gravitational Lensing using new HPC-Grid resources: the PI2S2 project

    NASA Astrophysics Data System (ADS)

    Becciani, U.; Antonuccio-Delogu, V.; Costa, A.; Comparato, M.

    2008-08-01

    We present the main project of the new grid infrastructure and the researches, that have been already started in Sicily and will be completed by next year. The PI2S2 project of the COMETA consortium is funded by the Italian Ministry of University and Research and will be completed in 2009. Funds are from the European Union Structural Funds for Objective 1 regions. The project, together with a similar project called Trinacria GRID Virtual Laboratory (Trigrid VL), aims to create in Sicily a computational grid for e-science and e-commerce applications with the main goal of increasing the technological innovation of local enterprises and their competition on the global market. PI2S2 project aims to build and develop an e-Infrastructure in Sicily, based on the grid paradigm, mainly for research activity using the grid environment and High Performance Computer systems. As an example we present the first results of a new grid version of FLY a tree Nbody code developed by INAF Astrophysical Observatory of Catania, already published in the CPC program Library, that will be used in the Weak Gravitational Lensing field.

  20. Transitions.

    ERIC Educational Resources Information Center

    Nathanson, Jeanne H., Ed.

    1993-01-01

    This theme issue on transitions for individuals with disabilities contains nine papers discussing transition programs and issues. "Transition Issues for the 1990s," by Michael J. Ward and William D. Halloran, discusses self-determination, school responsibility for transition, continued educational engagement of at-risk students, and service…

  1. Asp1 from Schizosaccharomyces pombe binds a [2Fe-2S](2+) cluster which inhibits inositol pyrophosphate 1-phosphatase activity.

    PubMed

    Wang, Huanchen; Nair, Vasudha S; Holland, Ashley A; Capolicchio, Samanta; Jessen, Henning J; Johnson, Michael K; Shears, Stephen B

    2015-10-27

    Iron-sulfur (Fe-S) clusters are widely distributed protein cofactors that are vital to cellular biochemistry and the maintenance of bioenergetic homeostasis, but to our knowledge, they have never been identified in any phosphatase. Here, we describe an iron-sulfur cluster in Asp1, a dual-function kinase/phosphatase that regulates cell morphogenesis in Schizosaccharomyces pombe. Full-length Asp1, and its phosphatase domain (Asp1(371-920)), were each heterologously expressed in Escherichia coli. The phosphatase activity is exquisitely specific: it hydrolyzes the 1-diphosphate from just two members of the inositol pyrophosphate (PP-InsP) signaling family, namely, 1-InsP7 and 1,5-InsP8. We demonstrate that Asp1 does not hydrolyze either InsP6, 2-InsP7, 3-InsP7, 4-InsP7, 5-InsP7, 6-InsP7, or 3,5-InsP8. We also recorded 1-phosphatase activity in a human homologue of Asp1, hPPIP5K1, which was heterologously expressed in Drosophila S3 cells with a biotinylated N-terminal tag, and then isolated from cell lysates with avidin beads. Purified, recombinant Asp1(371-920) contained iron and acid-labile sulfide, but the stoichiometry (0.8 atoms of each per protein molecule) indicates incomplete iron-sulfur cluster assembly. We reconstituted the Fe-S cluster in vitro under anaerobic conditions, which increased the stoichiometry to approximately 2 atoms of iron and acid-labile sulfide per Asp1 molecule. The presence of a [2Fe-2S](2+) cluster in Asp1(371-920) was demonstrated by UV-visible absorption, resonance Raman spectroscopy, and electron paramagnetic resonance spectroscopy. We determined that this [2Fe-2S](2+) cluster is unlikely to participate in redox chemistry, since it rapidly degraded upon reduction by dithionite. Biochemical and mutagenic studies demonstrated that the [2Fe-2S](2+) cluster substantially inhibits the phosphatase activity of Asp1, thereby increasing its net kinase activity. PMID:26422458

  2. Radiative lifetimes of the 2s2p2(4P) metastable levels of N III

    NASA Technical Reports Server (NTRS)

    Fang, Z.; Kwong, Victor H. S.; Parkinson, W. H.

    1993-01-01

    The radiative decay rates of N III 175 nm intersystem lines were measured in the laboratory by recording the time dependence of photon intensities emitted as the 2s2p2(4P) metastable term of N(2+) ions decay to the 2s22p(2P0) ground term. A cylindrical radio frequency ion trap was used to store the electron impact-produced N(2+) ions. The radiative decay signals were analyzed by multiexponential least-squares fits to the data. The measured radiative decay rates to the ground term are 1019(+/- 64)/s for 4P sub 1/2, 74.5(+/- 5.4)/s for 4P sub 3/2, and 308( +/- 22)/s for 4P sub 5/2. Comparisons of the measured values with theoretical values are presented.

  3. Ln3I5(S2N2)(S2)(THF)10 - a new type of molecular compounds.

    PubMed

    Fagin, A A; Fukin, G K; Cherkasov, A V; Shestakov, A F; Pushkarev, A P; Balashova, T V; Maleev, A A; Bochkarev, M N

    2016-03-21

    Unprecedented complexes of the composition Ln3I5(S2N2)(S2)(THF)10 were obtained in the reactions of neodymium and dysprosium iodide-nitrides with sulfur. The inorganic core of the molecules contains the cyclic fragments Ln(μ-S2)Ln, LnSNSN and LnSN. Ten of the fourteen atoms of the core are coplanar, the remaining four S2 and I2 atoms lie in the other two orthogonal planes. The dysprosium complex upon excitation with UV light exhibits the metal-centered luminescence characteristic of the Dy(3+) ion. Geometric parameters of the molecules, computational data, electron spectroscopy and fluorescence suggest the existence of some conjugation in the mentioned heterocycles. PMID:26842841

  4. A model for climate change education in formal and informal settings--C2S2 Climate Change Student Summit

    NASA Astrophysics Data System (ADS)

    Huffman, L. T.; Lynds, S. E.; Rack, F. R.

    2012-12-01

    Through a NOAA Environmental Literacy grant, ANDRILL (ANtarctic geological DRILLing) created a unique opportunity for both formal and informal educators to engage their classrooms/audiences in understanding the complexities of climate change. The program, entitled C2S2: Climate Change Student Summits, included excellent geographical coverage through an exceptional two-workshop professional development series for teachers in each of nine different regions representing the U.S. National Climate Assessment regions defined by the U.S. Global Change Research Program. The program also included a creative, investigative science research and presentation experience for teams of students in each region, culminating in the Climate Change Student Summit, an on-site capstone event including a videoconference connecting all sites. The success of this program is based on combining multiple aspects, such as providing professional development for educators and encouraging the active involvement of research scientists, both in the professional development workshops and in the Student Summit. Another key factor is the close working relationships between informal and formal education entities, including the involvement of informal science learning facilities and informal science education leaders. The program includes the creation and use of cutting-edge curriculum materials available in the ELF, (Environmental Literacy Framework with a focus on climate change) and hands-on resources for teachers and students that provide an earth systems approach to climate change education, which have been successfully used in grades 5-12 as well as at numerous science museums. The C2S2 project has completed four years of activities with demonstrated positive impacts on both students and teachers. This presentation will share the lessons learned about implementing this climate change science education program and suggest that it is a successful model that can be used to scale up this project from

  5. Transitions.

    ERIC Educational Resources Information Center

    Field, David; And Others

    1992-01-01

    Includes four articles: "Career Aspirations" (Field); "Making the Transition to a New Curriculum" (Baker, Householder); "How about a 'Work to School' Transition?" (Glasberg); and "Technological Improvisation: Bringing CNC to Woodworking" (Charles, McDuffie). (SK)

  6. Transition.

    ERIC Educational Resources Information Center

    Thompson, Sandy, Ed.; And Others

    1990-01-01

    This "feature issue" focuses on transition from school to adult life for persons with disabilities. Included are "success stories," brief program descriptions, and a list of resources. Individual articles include the following titles and authors: "Transition: An Energizing Concept" (Paul Bates); "Transition Issues for the 1990s" (William Halloran…

  7. Comparison of collisional radiative models for edge electron density reconstruction from Li I (2s-2p) emission profiles

    SciTech Connect

    Stoschus, H.; Hudson, B.; Munoz Burgos, J. M.; Thomas, D. M.; Schweinzer, J.

    2012-10-15

    Four collisional radiative models (CRMs) for reconstruction of the edge electron density profile from the measured Li I (2s-2p) emission profile of an accelerated lithium beam are compared using experimental data from DIII-D. It is shown for both L- and H-mode plasmas that edge density profiles reconstructed with the CRMs DDD2, ABSOLUT, [Sasaki et al. Rev. Sci. Instrum. 64, 1699 (1993)] and a new model developed at DIII-D agree in a density scan from n{sub e}{sup ped}= (2.0-6.5) Multiplication-Sign 10{sup 19} m{sup -3} within 20%, 20%, <5%, and 40%, respectively, of the pedestal density measured with Thomson scattering. Profile shape and absolute density vary in a scan of the effective ion charge Z{sub eff}= 1-6 up to a factor of two but agree with Thomson data for Z{sub eff}= 1-2 within the error bars.

  8. Single step transformation of sulphur to Li2S2/Li2S in Li-S batteries

    PubMed Central

    Helen, M.; Reddy, M. Anji; Diemant, Thomas; Golla-Schindler, Ute; Behm, R. Jürgen; Kaiser, Ute; Fichtner, Maximilian

    2015-01-01

    Lithium-sulphur batteries have generated tremendous research interest due to their high theoretical energy density and potential cost-effectiveness. The commercial realization of Li-S batteries is still hampered by reduced cycle life associated with the formation of electrolyte soluble higher-order polysulphide (Li2Sx, x = 4–8) intermediates, leading to capacity fading, self-discharge, and a multistep voltage profile. Herein, we have realized a practical approach towards a direct transformation of sulphur to Li2S2/Li2S in lithium-sulphur batteries by alteration of the reaction pathway. A coconut shell derived ultramicroporous carbon-sulphur composite cathode has been used as reaction directing template for the sulphur. The lithiation/delithiation and capacity fading mechanism of microporous carbon confined sulphur composite was revealed by analyzing the subsurface using X-ray photoelectron spectroscopy. No higher-order polysulphides were detected in the electrolyte, on the surface, and in the subsurface of the cathode composite. The altered reaction pathway is reflected by a single-step profile in the discharge/charge of a lithium-sulphur cell. PMID:26173723

  9. Single step transformation of sulphur to Li2S2/Li2S in Li-S batteries

    NASA Astrophysics Data System (ADS)

    Helen, M.; Reddy, M. Anji; Diemant, Thomas; Golla-Schindler, Ute; Behm, R. Jürgen; Kaiser, Ute; Fichtner, Maximilian

    2015-07-01

    Lithium-sulphur batteries have generated tremendous research interest due to their high theoretical energy density and potential cost-effectiveness. The commercial realization of Li-S batteries is still hampered by reduced cycle life associated with the formation of electrolyte soluble higher-order polysulphide (Li2Sx, x = 4-8) intermediates, leading to capacity fading, self-discharge, and a multistep voltage profile. Herein, we have realized a practical approach towards a direct transformation of sulphur to Li2S2/Li2S in lithium-sulphur batteries by alteration of the reaction pathway. A coconut shell derived ultramicroporous carbon-sulphur composite cathode has been used as reaction directing template for the sulphur. The lithiation/delithiation and capacity fading mechanism of microporous carbon confined sulphur composite was revealed by analyzing the subsurface using X-ray photoelectron spectroscopy. No higher-order polysulphides were detected in the electrolyte, on the surface, and in the subsurface of the cathode composite. The altered reaction pathway is reflected by a single-step profile in the discharge/charge of a lithium-sulphur cell.

  10. Cytotoxicity studies of water soluble coordination compounds with a [Mo2O2S2](2+) core.

    PubMed

    Gretarsdóttir, Johanna M; Bobersky, Sandra; Metzler-Nolte, Nils; Suman, Sigridur G

    2016-07-01

    Selected molybdenum sulfur compounds with the formulas (M)[Mo2O2S4L] where (Et4N)2(1), L=S4(2-), (Et4N)(2), L=Cp, (3), L=DMF, K(5), L=serine, M=Et4N(+), K(+), Na(+) and [Mo2O2S2L2] where Na2(4), L=cysteine, and (6), L=threonine, were prepared and subjected to cytotoxicity studies in vitro. The results were analyzed to rank the compounds according to their relative cytotoxicity and to correlate the observed toxicity to specific composition. The results guide future efforts to synthesize highly water soluble, non-toxic, compounds. Strong correlation was observed between toxicity and cation selection, as well as selection of biocompatible ligands combined with alkali metal salts. The most toxic compound analyzed showed about 50 times less cytotoxicity than the cisplatin reference compound in HT-29 cells. Preliminary results from in vivo data agree with the ranking obtained in vitro. PMID:26920227

  11. Single step transformation of sulphur to Li2S2/Li2S in Li-S batteries.

    PubMed

    Helen, M; Reddy, M Anji; Diemant, Thomas; Golla-Schindler, Ute; Behm, R Jürgen; Kaiser, Ute; Fichtner, Maximilian

    2015-01-01

    Lithium-sulphur batteries have generated tremendous research interest due to their high theoretical energy density and potential cost-effectiveness. The commercial realization of Li-S batteries is still hampered by reduced cycle life associated with the formation of electrolyte soluble higher-order polysulphide (Li2Sx, x = 4-8) intermediates, leading to capacity fading, self-discharge, and a multistep voltage profile. Herein, we have realized a practical approach towards a direct transformation of sulphur to Li2S2/Li2S in lithium-sulphur batteries by alteration of the reaction pathway. A coconut shell derived ultramicroporous carbon-sulphur composite cathode has been used as reaction directing template for the sulphur. The lithiation/delithiation and capacity fading mechanism of microporous carbon confined sulphur composite was revealed by analyzing the subsurface using X-ray photoelectron spectroscopy. No higher-order polysulphides were detected in the electrolyte, on the surface, and in the subsurface of the cathode composite. The altered reaction pathway is reflected by a single-step profile in the discharge/charge of a lithium-sulphur cell. PMID:26173723

  12. Pressure-induced metallization of dense (H2S)2H2 with high-Tc superconductivity

    PubMed Central

    Duan, Defang; Liu, Yunxian; Tian, Fubo; Li, Da; Huang, Xiaoli; Zhao, Zhonglong; Yu, Hongyu; Liu, Bingbing; Tian, Wenjing; Cui, Tian

    2014-01-01

    The high pressure structures, metallization, and superconductivity of recently synthesized H2-containing compounds (H2S)2H2 are elucidated by ab initio calculations. The ordered crystal structure with P1 symmetry is determined, supported by the good agreement between theoretical and experimental X-ray diffraction data, equation of states, and Raman spectra. The Cccm structure is favorable with partial hydrogen bond symmetrization above 37 GPa. Upon further compression, H2 molecules disappear and two intriguing metallic structures with R3m and Im-3m symmetries are reconstructive above 111 and 180 GPa, respectively. The predicted metallization pressure is 111 GPa, which is approximately one-third of the currently suggested metallization pressure of bulk molecular hydrogen. Application of the Allen-Dynes-modified McMillan equation for the Im-3m structure yields high Tc values of 191 K to 204 K at 200 GPa, which is among the highest values reported for H2-rich van der Waals compounds and MH3 type hydride thus far. PMID:25382349

  13. Femtosecond induced transparency and absorption in the extremeultraviolet by coherent coupling of the He 2s2p (1Po) and 2p2 (1Se)double excitation states with 800 nm light

    SciTech Connect

    Loh, Z.-H.; Greene, C.H.; Leone, S.R.

    2007-08-01

    Femtosecond high-order harmonic transient absorption spectroscopy is used to observe electromagnetically induced transparency-like behavior as well as induced absorption in the extreme ultraviolet by laser dressing of the He 2s2p ({sup 1}P{sup 0}) and 2p{sup 2} ({sup 1}S{sup e}) double excitation states with an intense 800 nm field. Probing in the vicinity of the 1s{sup 2} {yields} 2s2p transition at 60.15 eV reveals the formation of an Autler-Townes doublet due to coherent coupling of the double excitation states. Qualitative agreement with the experimental spectra is obtained only when optical field ionization of both double excitation states into the N = 2 continuum is included in the theoretical model. Because the Fano q-parameter of the unperturbed probe transition is finite, the laser-dressed He atom exhibits both enhanced transparency and absorption at negative and positive probe energy detunings, respectively.

  14. Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N2S2 Synthetic Models of NiSOD

    PubMed Central

    Broering, Ellen P.; Dillon, Stephanie; Gale, Eric M.; Steiner, Ramsey A.; Telser, Joshua; Brunold, Thomas C.; Harrop, Todd C.

    2015-01-01

    Superoxide dismutase (SOD) catalyzes the disproportionation of superoxide (O2• −) into H2O2 and O2(g) by toggling through different oxidation states of a first-row transition metal ion at its active site. Ni-containing SODs (NiSODs) are a distinct class of this family of metalloenzymes due to the unusual coordination sphere that is comprised of mixed N/S-ligands from peptide-N and cysteine-S donor atoms. A central goal of our research is to understand the factors that govern reactive oxygen species (ROS) stability of the Ni–S(Cys) bond in NiSOD utilizing a synthetic model approach. In light of the reactivity of metal-coordinated thiolates to ROS, several hypotheses have been proffered and include the coordination of His1-Nδ to the Ni(II) and Ni(III) forms of NiSOD, as well as hydrogen bonding or full protonation of a coordinated S(Cys). In this work, we present NiSOD analogues of the general formula [Ni(N2S)(SR′)]−, providing a variable location (SR′ = aryl thiolate) in the N2S2 basal plane coordination sphere where we have introduced o-amino and/or electron-withdrawing groups to intercept an oxidized Ni species. The synthesis, structure, and properties of the NiSOD model complexes (Et4N)[Ni(nmp)(SPh-o-NH2)] (2), (Et4N)[Ni(nmp)(SPh-o-NH2-p-CF3)] (3), (Et4N)[Ni(nmp)(SPh-p-NH2)] (4), and (Et4N)[Ni(nmp)(SPh-p-CF3)] (5) (nmp2− = dianion of N-(2-mercaptoethyl)picolinamide) are reported. NiSOD model complexes with amino groups positioned ortho to the aryl-S in SR′ (2 and 3) afford oxidized species (2ox and 3ox) that are best described as a resonance hybrid between Ni(III)-SR and Ni(II)-•SR based on ultraviolet–visible (UV-vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectroscopies, as well as density functional theory (DFT) calculations. The results presented here, demonstrating the high percentage of S(3p) character in the highest occupied molecular orbital (HOMO) of the four-coordinate reduced form of NiSOD (Ni

  15. The promoter effect and a rate expression of the catalytic incineration of (CH3)2S2 over an improved CuO-MoO3/gamma-Al2O3 catalyst.

    PubMed

    Wang, Ching-Huei; Lin, Shiow-Shyung; Liou, Shen-Ben; Weng, Hung-Shan

    2002-10-01

    The CuO-MoO3/gamma-Al2O3 catalyst, confirmed previously as having good activity in the catalytic incineration of (CH3)2S2, was employed as the principal catalyst in this study. With the aim of improving catalyst activity and resistance to deactivation by sulfur compounds, a promoter was added either before adding the precursors of Cu and Mo or together with Cu and Mo onto the gamma-Al2O3. Promoters included transition metals and elements from groups IA-VIIA in the chemical periodic table. Experimental results reveal Cr2O3 as the most effective promoter, with an optimal composition of 5 wt.% Cu, 6 wt.% Mo and 4 wt.% Cr (designated as Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3). Knowing that higher acidity can improve activity, we further investigated the effect of acid treatment on the performance of the Cu(5)-Mo(6)-Cr(4)/gamma-Al2O3 catalyst. Experimental results indicate the H2SO4-treated catalyst (Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3) has a better activity and durability. A study for finding an appropriate rate expression for the catalytic incineration of (CH3)2S2 by Cu(5)-Mo(6)-Cr(4)/sulfated-gamma-Al2O3 was carried out in a differential reactor. The results show that the Mars-Van Krevelen model is applicable to this destructive oxidation reaction. Results additionally reveal that competitive adsorption of CH4 reduces conversion of (CH3)2S2. PMID:12365836

  16. Role of cascade and Auger effects in the enhanced population of the C{sup 3+}(1s2s2p {sup 4}P) states following single-electron capture in C{sup 4+}(1s2s {sup 3}S)-He collisions

    SciTech Connect

    Roehrbein, D.; Kirchner, T.; Fritzsche, S.

    2010-04-15

    The population of excited three-electron states in carbon ions after single-electron capture in 0.5-1.1 MeV/amu C{sup 4+}(1s2s {sup 3}S)-He collisions is analyzed theoretically by combining different methods. While the two-center basis generator method is used to calculate capture amplitudes on the single-particle level, all-electron structure calculations for the relevant C{sup 3+} states and their radiative and Auger transition rates are performed on the multiconfiguration Dirac-Fock level. These data are then combined and fed into a set of classical rate equations for the decay dynamics. Total cross sections for the production of the 1s2s2p {sup 4}P, 1s2s2p {sup 2}P{sub -}, and 1s2s2p {sup 2}P{sub +} states are calculated and their ratios compared with recent experimental data and previous calculations [D. Strohschein et al., Phys. Rev. A 77, 022706 (2008)]. It is found that the relative intensities of the 1s2s2p {sup 4}P states are considerably larger than expected on the basis of pure spin statistics. The Auger transitions, which were not included in the previous calculations, have a significant effect on the final results in that they reduce the 1s2s2p {sup 2}P intensities. Although our extended computations explain a significant part of the production of the 1s2s2p {sup 4}P states, the experimentally observed enhancement of these states is still considerably larger than the theoretical one.

  17. Versatile N2S2 nickel-dithiolates as mono- and bridging bidentate, S-donor ligands to gold(I).

    PubMed

    Pinder, Tiffany A; Montalvo, Steven K; Lunsford, Allen M; Hsieh, Chung-Hung; Reibenspies, Joseph H; Darensbourg, Marcetta Y

    2014-01-01

    Development of square planar cis-dithiolate nickel complexes as metallo S-donor ligands focuses on the synthesis and structures of gold(I) heterometallic clusters derived from assemblage with three NiN2S2 complexes: Ni(bme-daco), Ni(bme-dach) and Ni(ema)(2-) (bme-daco = (bismercaptoethanediazacyclooctane); bme-dach = bismercaptoethanediazacycloheptane; and ema = N,N'-ethylenebis-2-mercaptoacetamide). With Ph3PAuCl as the gold source, examples of simple S-aurolation retaining the PPh3 on Au(+) were obtained for [{Ni(bme-daco)}AuPPh3](+)Cl(-) and [{Ni(ema)}2Au4(PPh3)4], where the latter complex demonstrated unsupported aurophilic interactions between [{Ni(ema)}Au2(PPh3)2] units in its X-ray crystal structure (Au-Au = 3.054 and 3.127 Å). Three compounds containing fully-supported digold units with Au-Au distances in the aurophilic range of 3.11 to 3.13 Å were found as stair-step structures in which planar NiN2S2 step treads are connected by planar S2Au2S2 risers at ca. 90°: [{Ni(bme-daco)}2Au2](2+)(Cl(-))2; [{Ni(bme-dach)}2Au2](2+)(Cl(-))2; and (Et4N(+))2[{Ni(ema)}2Au2](2-). Electrochemical data from cyclic voltammograms demonstrated a positive shift in Ni(II/I) couples for the [{NiN2S2}xAuy] complexes as compared to the NiN2S2 precursors and a ca. 700 mV decrease in communication between multiple NiN2S2 units as compared to [{NiN2S2}2Ni](2+) analogues in slant chair conformation. The analogy between NiN2S2 metallodithiolate ligands and diphosphine ligands holds here as in other examples of inorganic and organometallic complexes. PMID:24108061

  18. Spin-statistic selection rules for multiphoton transitions: Application to helium atoms

    NASA Astrophysics Data System (ADS)

    Zalialiutdinov, T.; Solovyev, D.; Labzowsky, L.; Plunien, G.

    2016-01-01

    A theoretical investigation of the three-photon transition rates 2 1P1→2 1S0,1 1S0 and 2 3P2→2 1S0,1 1S0 for the helium atom is presented. Photon energy distributions and precise values of the nonrelativistic transition rates are obtained with employment of correlated wave functions of the Hylleraas type. The possible experiments for the tests of the Bose-Einstein statistics for multiphoton systems are discussed.

  19. Bandgap narrowing in the layered oxysulfide semiconductor Ba3Fe2O5Cu2S2: Role of FeO2 layer

    NASA Astrophysics Data System (ADS)

    Han, Zhang; Shifeng, Jin; Liwei, Guo; Shijie, Shen; Zhiping, Lin; Xiaolong, Chen

    2016-02-01

    A new layered Cu-based oxychalcogenide Ba3Fe2O5Cu2S2 has been synthesized and its magnetic and electronic properties were revealed. Ba3Fe2O5Cu2S2 is built up by alternatively stacking [Cu2S2]2- layers and iron perovskite oxide [(FeO2)(BaO)(FeO2)]2- layers along the c axis that are separated by barium ions with Fe3+ fivefold coordinated by a square-pyramidal arrangement of oxygen. From the bond valence arguments, we inferred that in layered CuCh-based (Ch = S, Se, Te) compounds the +3 cation in perovskite oxide sheet prefers a square pyramidal site, while the lower valence cation prefers the square planar sites. The studies on susceptibility, transport, and optical reflectivity indicate that Ba3Fe2O5Cu2S2 is an antiferromagnetic semiconductor with a Néel temperature of 121 K and an optical bandgap of 1.03 eV. The measurement of heat capacity from 10 K to room temperature shows no anomaly at 121 K. The Debye temperature is determined to be 113 K. Theoretical calculations indicate that the conduction band minimum is predominantly contributed by O 2p and 3d states of Fe ions that antiferromagnetically arranged in FeO2 layers. The Fe 3d states are located at lower energy and result in a narrow bandgap in comparison with that of the isostructural Sr3Sc2O5Cu2S2. Project supported by the National Natural Science Foundation of China (Grant Nos. 51472266, 51202286, and 91422303), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020100) and the ICDD.

  20. (Ba1-xKx)(Cu2-xMnx)Se2: A copper-based bulk form diluted magnetic semiconductor with orthorhombic BaCu2S2-type structure

    NASA Astrophysics Data System (ADS)

    Guo, Shengli; Man, Huiyuan; Gong, Xin; Ding, Cui; Zhao, Yao; Chen, Bin; Guo, Yang; Wang, Hangdong; Ning, F. L.

    2016-02-01

    A new copper-based bulk form diluted magnetic semiconductor (DMS) (Ba1-xKx)(Cu2-xMnx)Se2 (x=0.075, 0.10, 0.125, and 0.15) with TC ∼18 K has been synthesized. K substitution for Ba introduces hole-type carriers, while Mn substitution for Cu provides local spins. Different from previous reported DMSs, this material crystallizes into orthorhombic BaCu2S2-type crystal structure. No ferromagnetism is observed when only doping Mn, and clear ferromagnetic transition and hysteresis loop have been observed as K and Mn are codoped into the parent compound BaCu2Se2.

  1. Structural and physical properties of the ferromagnetic tris-dithiooxalato compounds, A[M(II)Cr(III)(C(2)S(2)O(2))(3)], with A(+) = N(n-C(n)()H(2)(n)(+1))(4)(+) (n = 3-5) and P(C(6)H(5))(4)(+) and M(II) = Mn, Fe, Co, and Ni.

    PubMed

    Bradley, Justin M; Carling, Simon G; Visser, Dirk; Day, Peter; Hautot, Dimitri; Long, Gary J

    2003-02-24

    The structural and magnetic properties of the tris-dithiooxalato salts, A[M(II)Cr(C(2)S(2)O(2))(3)], have been investigated with A(+) = PPh(4)(+), N(n-C(n)()H(2)(n)()(+1))(4)(+), with n = 3-5, where M(II) is Mn, Fe, Co, and Ni. With the exception of A[MnCr(C(2)S(2)O(2))(3)], all the salts are ferromagnets with Curie temperatures, T(c), between 5 and 16 K. In contrast to the corresponding oxalates which are ferromagnetic, the A[MnCr(C(2)S(2)O(2))(3)] compounds are paramagnetic above 2 K. Powder neutron diffraction studies of d(20)-PPh(4)[FeCr(C(2)S(2)O(2))(3)] indicate that no structural phase transitions occur between 2.4 and 285 K and that the coefficient of linear expansion is four times larger for the c-axis than for the a-axis. The crystal structure refined from powder neutron diffraction data confirms the honeycomb layer arrangement observed in the related bimetallic tris-oxalate salts. The Mössbauer spectra reveal that the iron(II) in PPh(4)[FeCr(C(2)S(2)O(2))(3)] is coordinated mainly to six oxygen atoms of the dithiooxalato ligand but with a minor component of sulfur coordination that increases with aging of the sample; the iron(II) is high-spin in both cases. Powder neutron diffraction profiles of d(20)-PPh(4)[FeCr(C(2)S(2)O(2))(3)] below T(c) show magnetic intensity with a q = 0 propagation vector, confirming the presence of ferromagnetic order. PMID:12588130

  2. Calculation of the Ti(C y N1- y )-Ti4C2S2-MnS-austenite equilibrium in Ti-bearing steels

    NASA Astrophysics Data System (ADS)

    Liu, W. J.; Jonas, J. J.

    1989-08-01

    A thermodynamic model is presented for the equilibria among various precipitates (Ti(C y N1- y ), Ti4C2S2, and MnS) and austenite containing six alloying elements (C, Mn, N, S, Si, and Ti). This model is applied to four microalloyed steels with Ti levels of 0.05, 0.11, 0.18, and 0.25 pct. The calculations show that the Ti in these steels cannot be completely dissolved over the austenite temperature range. However, the compositions of the undissolved Ti carbonitrides differ significantly from pure TiN, as 10 to 40 pct of the nitrogen is replaced by carbon. An expression for the Gibbs energy for the formation of Ti4C2S2 in austenite is estimated. The present predictions are compared with those of the Hudd, Jones, and Kale (HJK) model; considerable differences are observed at temperatures below 1250°C.

  3. The kinetics of catalytic incineration of (CH3)2S2 over the CuO-MoO3/gamma-Al2O3 catalyst.

    PubMed

    Wang, Ching-Huei; Lin, Shiow-Shyung; Weng, Hung-Shan

    2002-10-01

    In this study, by varying reaction conditions including particle size, space velocity, reactant concentration and reaction temperature, the kinetics of catalytic incineration of (CH3)2S2 catalyzed by the CuO-MoO3/gamma-Al2O3 catalyst was investigated. Three kinetic models, i.e., the power-rate law model, Langmuir-Hinshelwood model and Mars-Van Krevelen model, were applied to best fit the experimental results. It was shown that the Mars-Van Krevelen model was more appropriate than the other two models for describing the mechanism of catalytic incineration of (CH3)2S2 on the CuO-MoO3/gamma-Al2O3 catalyst. The reaction expression of the Mars-Van Krevelen model was as follows: -r=k(R)k(O)C(R)C(O) divided by alpha(k)(R)C(R) + k(O)C(O) where alpha is 5.5 and C(R) and C(O) represent concentrations of (CH3)2S2 and O2, respectively. The enlarged difference between experimental and predicted data was observed at higher operating temperatures. This might be due to the dominating mechanism at this temperature region was different. PMID:12403014

  4. Charge-exchange-induced two-electron satellite transitions from autoionizing levels in dense plasmas.

    PubMed

    Rosmej, F B; Griem, H R; Elton, R C; Jacobs, V L; Cobble, J A; Faenov, A Ya; Pikuz, T A; Geissel, M; Hoffmann, D H H; Süss, W; Uskov, D B; Shevelko, V P; Mancini, R C

    2002-11-01

    Order-of-magnitude anomalously high intensities for two-electron (dielectronic) satellite transitions, originating from the He-like 2s(2) 1S0 and Li-like 1s2s(2) (2)S(1/2) autoionizing states of silicon, have been observed in dense laser-produced plasmas at different laboratories. Spatially resolved, high-resolution spectra and plasma images show that these effects are correlated with an intense emission of the He-like 1s3p 1P-1s(2) 1S lines, as well as the K(alpha) lines. A time-dependent, collisional-radiative model, allowing for non-Maxwellian electron-energy distributions, has been developed for the determination of the relevant nonequilibrium level populations of the silicon ions, and a detailed analysis of the experimental data has been carried out. Taking into account electron density and temperature variations, plasma optical-depth effects, and hot-electron distributions, the spectral simulations are found to be not in agreement with the observations. We propose that highly stripped target ions (e.g., bare nuclei or H-like 1s ground-state ions) are transported into the dense, cold plasma (predominantly consisting of L- and M-shell ions) near the target surface and undergo single- and double-electron charge-transfer processes. The spectral simulations indicate that, in dense and optically thick plasmas, these charge-transfer processes may lead to an enhancement of the intensities of the two-electron transitions by up to a factor of 10 relative to those of the other emission lines, in agreement with the spectral observations. PMID:12513602

  5. Calculations of resonances parameters for the ((2s2) 1Se, (2s2p) 1,3P0) and ((3s2) 1Se, (3s3p) 1,3P0) doubly excited states of helium-like ions with Z≤10 using a complex rotation method implemented in Scilab

    NASA Astrophysics Data System (ADS)

    Gning, Youssou; Sow, Malick; Traoré, Alassane; Dieng, Matabara; Diakhate, Babacar; Biaye, Mamadi; Wagué, Ahmadou

    2015-01-01

    In the present work a special computational program Scilab (Scientific Laboratory) in the complex rotation method has been used to calculate resonance parameters of ((2s2) 1Se, (2s2p) 1,3P0) and ((3s2) 1Se, (3s3p) 1,3P0) states of helium-like ions with Z≤10. The purpose of this study required a mathematical development of the Hamiltonian applied to Hylleraas wave function for intrashell states, leading to analytical expressions which are carried out under Scilab computational program. Results are in compliance with recent theoretical calculations.

  6. Draft Genome Sequence of Aeromonas dhakensis Strain F2S2-1, Isolated from the Skin Surface of an Indian Oil Sardine (Sardinella longiceps)

    PubMed Central

    Nadiga, Mohan; Vaidyanathan, V. V.

    2016-01-01

    Draft genome sequencing of Aeromonas dhakensis strain F2S2-1, isolated from the skin surface of an Indian oil sardine (Sardinella longiceps), has been carried out. The draft genome was roughly 4.7 Mb in size with 61.7% G+C content. Annotation of the genome yielded 4,337 genes coding for proteins, tRNAs, and rRNAs. Annotation also revealed the presence of 52 genes linked to resistance to antibiotics/toxic compounds. Pathway analysis revealed the presence of novobiocin biosynthetic genes and genes for biosynthesis of a siderophore group on nonsynthetic peptides. PMID:27540048

  7. Site requirements for the reactions of CH 3SH and (CH 3) 2S 2 on ZnO( 1 0 1¯ 0)

    NASA Astrophysics Data System (ADS)

    Halevi, B.; Vohs, John M.

    Temperature programmed desorption (TPD) was used to investigate the adsorption and reaction of CH 3SH and (CH 3) 2S 2 on the nonpolar ( 1 0 1¯ 0) surface of ZnO. Methanethiol was found to dissociate on the ( 1 0 1¯ 0) surface to produce adsorbed methylthiolates. The primary reaction pathways for the methylthiolates were methyl group transfer between adjacent thiolates to produce (CH 3) 2S at 510 K, and transfer of methyl groups to surface lattice oxygen to produce adsorbed methoxides which were oxidized to CH 2O at 525 K and adsorbed formate. Dimethyldisulfide was found to dissociate via cleavage of the S-S bond to form adsorbed methylthiolates. The reaction pathways for thiolates produced in this manner were similar to those produced from CH 3SH except for an additional low-temperature pathway for the production of CH 2O. Comparison of the results obtained in this study to our previous study of the reaction of CH 3SH and (CH 3) 2S 2 on ZnO(0 0 0 1) and published STM studies of ZnO( 1 0 1¯ 0) and ZnO(0 0 0 1) indicates that step edges are the active sites for the reaction of thiols and disulfides on these surfaces.

  8. Crystal Structure and Thermoelectric Properties of Misfit-Layered Sulfides [Ln2S2] p NbS2 (Ln = Lanthanides)

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzuru; Ogawa, Hidenori; Nakajo, Takaki; Kikuchii, Yuta; Hayashi, Kei

    2013-07-01

    Polycrystalline samples of misfit-layered sulfides [Ln2S2] p NbS2 (Ln = lanthanides) have been prepared using the CS2 sulfidation method. Except for Ln = Eu and Lu, single-phase samples were prepared. The compounds consist of an alternate stacking of a trigonal prism-type [NbS2] layer and a double-layered NaCl [rock salt (RS)]-type [Ln2S2] block, parallel to the c-axis. Three types of stacking modes of the [NbS2] layer and the RS-type block have been confirmed with a (3 + 1)-dimensional superspace group description: two face-centered orthorhombic structures and one face-centered monoclinic structure. Slightly cation-deficient samples with Ln = Yb exhibit the highest Seebeck coefficient S ≈ 59 μV/K. With electrical resistivity of ρ = 1.4 m Upomega cm and thermal conductivity of κ = 0.69 W/Km, this yields a dimensionless figure of merit of ZT = 0.11 at 300 K.

  9. Electronic, magnetic and structural properties of neutral, cationic and anionic Fe2S2, Fe3S4 and Fe4S4 clusters

    NASA Astrophysics Data System (ADS)

    Tazibt, S.; Bouarab, S.; Ziane, A.; Parlebas, J. C.; Demangeat, C.

    2010-08-01

    This work reports density functional calculations of geometric, electronic and magnetic properties of freestanding iron-sulfur Fe2S2, Fe3S4 and Fe4S4 clusters which are the ones most frequently contained in proteins. We investigate neutral, anionic and cationic clusters using a method that employs linear combinations of atomic orbitals as basis sets, nonlocal norm-conserving pseudopotentials and a generalized gradient approximation to exchange and correlation. The results are discussed in connection with available experimental data. We mainly show that the ground-state geometries of these free clusters are consistent with their structures in core proteins and they are the same in the neutral, anionic and cationic states, but with small distortions. In all cases, an antiferromagnetic order between Fe atoms is always preferred to ferromagnetic and paramagnetic ones. The geometric distortions induced by magnetism decrease with cluster size and the maximum deviation between Fe-Fe distances is 11% in Fe2S2, but only 4% in Fe3S4 and 3% in Fe4S4 clusters.

  10. The sulfur depletion problem: upper limits on the H2S2, HS·2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422

    NASA Astrophysics Data System (ADS)

    Martín-Doménech, R.; Jiménez-Serra, I.; Muñoz Caro, G. M.; Müller, H. S. P.; Occhiogrosso, A.; Testi, L.; Woods, P. M.; Viti, S.

    2016-01-01

    Context. A fraction of the missing sulfur in dense clouds and circumstellar regions could be in the form of three species not yet detected in the interstellar medium: H2S2, HS.2, and S2 according to experimental simulations performed under astrophysically relevant conditions. These S-S bonded molecules can be formed by the energetic processing of H2S-bearing ice mantles on dust grains, and subsequently desorb to the gas phase. Aims: The detection of these species could partially solve the sulfur depletion problem, and would help to improve our knowledge of the poorly known chemistry of sulfur in the interstellar medium. To this purpose we calculated the frequencies and expected intensities of the rotational transitions not previously reported, and performed dedicated ground-based observations toward the low-mass warm core IRAS 16293-2422, a region with one of the highest measured gas-phase H2S abundances. Methods: Observations in the submillimeter regime were obtained with the APEX 12 m telescope during 15 h of observation. A total of ~16 GHz were covered in a range of about 100 GHz, targeting a wide selection of the predicted rotational transitions of the three molecules. Results: The 1σ noise rms values were extracted in the spectral regions where the targeted species should have been detected. These values were a factor of 2-7 lower than those reached by previous observations toward the same source, and allowed us to estimate a 1σ upper limit to their molecular abundances of ≤8.1 × 10-9, ≤ 1.1 × 10-8, and ≤ 2.9 × 10-7 relative to H2, for H2S 2 , HS.2, and S2, respectively. Conclusions: The upper limit abundances of the three molecules containing the S2 unit are up to two orders of magnitude lower than the H2S abundance in the source, and one order of magnitude lower than the expected abundances from the experimental simulations using ice analogs. Subsequent gas-phase chemistry after desorption could lower the abundances of the three species to

  11. Novel opioid peptide derived antagonists containing (2S)-2-methyl-3-(2,6-dimethyl-4-carbamoylphenyl)propanoic acid [(2S)-Mdcp].

    PubMed

    Ghosh, Animesh; Luo, Jie; Liu, Chen; Weltrowska, Grazyna; Lemieux, Carole; Chung, Nga N; Lu, Yixin; Schiller, Peter W

    2008-09-25

    A synthesis of the novel tyrosine analogue (2 S)-2-methyl-3-(2,6-dimethyl-4-carbamoylphenyl)propanoic acid [(2 S)-Mdcp] (15) was developed. In (2 S)-Mdcp, the amino and hydroxyl groups of 2',6'-dimethyltyrosine are replaced by a methyl and a carbamoyl group, respectively, and its substitution for Tyr (1) in opioid agonist peptides resulted in compounds showing antagonism at all three opioid receptors. The cyclic peptide (2 S)-Mdcp-c[D-Cys-Gly-Phe(pNO 2)-D-Cys]NH 2 (1) was a potent and selective mu antagonist, whereas (2 S)-Mdcp-c[D-Pen-Gly-Phe(pF)-Pen]-Phe-OH (3) showed subnanomolar delta antagonist activity and extraordinary delta selectivity. PMID:18800771

  12. Novel Opioid Peptide Derived Antagonists Containing (2S)-2-Methyl-3-(2,6-dimethyl-4-carbamoylphenyl)propanoic Acid [(2S)-Mdcp

    PubMed Central

    Ghosh, Animesh; Luo, Jie; Liu, Chen; Weltrowska, Grazyna; Lemieux, Carole; Chung, Nga N.; Lu, Yixin; Schiller, Peter W.

    2009-01-01

    A synthesis of the novel tyrosine analogue (2S)-2-methyl-3-(2,6-dimethyl-4-carbamoylphenyl)propanoic acid [(2S)-Mdcp] (15) was developed. In (2S)-Mdcp the amino- and hydroxyl groups of 2',6'-dimethyltyrosine are replaced by a methyl- and a carbamoyl group, respectively, and its substitution for Tyr1 in opioid agonist peptides resulted in compounds showing antagonism at all three opioid receptors. The cyclic peptide (2S)-Mdcp-c[D-Cys-Gly-Phe(pNO2)-D-Cys]NH2 (1) was a potent and selective μ antagonist, whereas (2S)-Mdcp-c[D-Pen-Gly-Phe(pF)-Pen]-Phe-OH (3) showed subnanomolar δ antagonist activity and extraordinary δ selectivity. PMID:18800771

  13. Analysis of 1s(2s2p {sup 3}P)nl Rydberg states in the K-shell photoionization of the Be atom

    SciTech Connect

    Yoshida, Fumiko; Matsuoka, Leo; Takashima, Ryuta; Hasegawa, Shuichi; Nagata, Tetsuo; Azuma, Yoshiro; Obara, Satoshi; Koike, Fumihiro

    2006-06-15

    We have observed inner-shell photoionization of Be using synchrotron radiation in the energy region of the 1s(2s2p {sup 3}P)nl Rydberg states. We used a time-of-flight method to distinguish singly and doubly charged photoions and obtained the Be{sup +} [ns; n=5-12 ({sup 1}P)3s] and Be{sup 2+} [ns; n=5-8, nd=5,6 ({sup 1}P)3s] ion spectra with high resolution corresponding to an instrumental bandpass of 13 meV. Detailed analysis enabled the autoionization parameters, resonance energy position E{sub 0}, resonance width {gamma}, and Fano parameter q, to be obtained. From the resonance positions of the {sup 3}Pnl series members, the series limit was determined to be 127.97 eV, which is in good agreement with previous experiments.

  14. Fine structure and ionization energy of the 1s2s2p 4P state of the helium negative ion He-.

    PubMed

    Wang, Liming; Li, Chun; Yan, Zong-Chao; Drake, G W F

    2014-12-31

    The fine structure and ionization energy of the 1s2s2p (4)P state of the helium negative ion He(-) are calculated in Hylleraas coordinates, including relativistic and QED corrections up to O(α(4)mc(2)), O((μ/M)α(4)mc(2)), O(α(5)mc(2)), and O((μ/M)α(5)mc(2)). Higher order corrections are estimated for the ionization energy. A comparison is made with other calculations and experiments. We find that the present results for the fine structure splittings agree with experiment very well. However, the calculated ionization energy deviates from the experimental result by about 1 standard deviation. The estimated theoretical uncertainty in the ionization energy is much less than the experimental accuracy. PMID:25615325

  15. Free-Spinning-Tunnel Investigation of a 1/24-Scale Model of the Grumman AF-2S, -2W Airplane

    NASA Technical Reports Server (NTRS)

    Klinar, Walter J.; Wilson, Jack H.

    1950-01-01

    An investigation of the spin and recovery characteristics of a 1/24-scale model of the Grumman AF-2S, -2W airplane was conducted in the Langley 20-foot free-spinning tunnel. The effects of controls on the erect and inverted spin and recovery characteristics for a range of possible loadings of the.airplane were determined. The effect of a revised-tail installation (small dual fins added to the stabilizer of the original tail and the vertical-tail height of the original tail increased) and the effect of various ventral-fin and antispin-fillet installations were determined. The investigation also included spin-recovery parachute tests.

  16. Single Use Letter Report for the Verification and Validation of the RADNUC-2A and ORIGEN2 S.2 Computer Codes

    SciTech Connect

    PACKER, M.J.

    2000-06-20

    This report documents the verification and validation (V&V) activities undertaken to support the use of the RADNUC2-A and ORIGEN2 S.2 computer codes for the specific application of calculating isotopic inventories and decay heat loadings for Spent Nuclear Fuel Project (SNFP) activities as described herein. Two recent applications include the reports HNF-SD-SNF-TI-009, 105-K Basin Material Design Basis Feed Description for Spent Nuclear Fuel Project Facilities, Volume 1, Fuel (Praga, 1998), and HNF-3035, Rev. 0B, MCO Gas Composition for Low Reactive Surface Areas (Packer, 1998). Representative calculations documented in these two reports were repeated using RADNUC2-A, and the results were identical to the documented results. This serves as verification that version 2A of Radnuc was used for the applications noted above; the same version was tested herein, and perfect agreement was shown. Comprehensive V&V is demonstrated for RADNUC2-A in Appendix A.

  17. Solvatochromism, spectral properties and antimicrobial activities of new azo-azomethine dyes with N2S2O2 donor set of atoms

    NASA Astrophysics Data System (ADS)

    Khanmohammadi, Hamid; Pass, Maryam; Rezaeian, Khatereh; Talei, Gholamreza

    2014-08-01

    Six new azo-azomethine dyes, H2Ln (n = 1-6), with N2S2O2 donor set of atoms have been prepared via condensation reaction of 1,10-diaza-4,7-dithiadecane, I, with substituted azo-coupled salicylaldehyde. The dyes were characterized by IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis. The solvatochromic behavior of the dyes was also probed by studying their UV-Vis spectra in four pure organic solvents of different polarities and a meaningful correlation was observed. Furthermore, all prepared dyes were assayed for their antibacterial and antifungal activities by disc diffusion method. The results indicated that all prepared dyes show good inhibition against Staphylococcus epidermidis and Bacillus cereus and did not show any antibacterial activity against Escherichia coli as compared to standard drugs.

  18. (1S,2R,2'S)- and (1S,2S, 2'S)-1-phenyl-2-phenylthio-2-(tetrahydropyran-2'-ylthio)ethanol diastereoisomers at 193 K.

    PubMed

    Kansikas, J; Sipilä, K

    2000-11-01

    In the synthesis of 1-phenyl-2-phenylthio-2-(tetrahydropyran-2-ylthio)ethanol, C(19)H(22)O(2)S(2), four diastereoisomers are formed. Two non-centrosymmetric enantiomeric forms which crystallize in space groups P2(1)2(1)2(1) and Pna2(1) are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c-axis direction; the O.O distances are 2.962 (4) and 2.764 (3) A, respectively. The tetrahydropyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter molecule. PMID:11077307

  19. Degradations of acetaminophen via a K2S2O8-doped TiO2 photocatalyst under visible light irradiation.

    PubMed

    Lin, Justin Chun-Te; de Luna, Mark Daniel G; Aranzamendez, Graziel L; Lu, Ming-Chun

    2016-07-01

    Acetaminophen (ACT) is a mild analgesic commonly used for relief of fever, headache and some minor pains. It had been detected in both fixed factory-discharged wastewaters, and diverse sources, e.g. surface waters during festival events. Degradation of such trace emergent pollutants by titanium dioxide (TiO2) photocatalysts is a common approach; however, the band gap that can be utilized in the UV range is limited. In order to extend downward the energy required to excite the photocatalytic material, doping with potassium peroxodisulfate (K2S2O8) by a sol-gel method was done in this work. The visible-light active photocatalyst was tested on the degradation of ACT under four parameters including: initial ACT concentration, catalyst dose, initial pH, and system temperature. Optimal conditions, which achieved 100% ACT degradation, were obtained by using 0.1 mM ACT initial concentration, catalyst dose of 1 g L(-1), initial pH of 9.0 and system temperature of 22 °C at the end of 9-h irradiation. Meanwhile, three types of degradation kinetic models (i.e. zero, pseudo first and second order) were tested. The feasible model followed a pseudo-first order model with the computed constant (kapp) of 7.29 × 10(-3) min(-1). The present study provides a better photocatalytic degradation route by K2S2O8-modified TiO2 in comparison with pristine TiO2, in wastewater treatment dealing with ACT and other persistent organic pollutants. PMID:27135700

  20. Characterization of the nicotinic ligand 2-[18F]fluoro-3-[2(S)-2-azetidinylmethoxy]pyridine in vivo.

    PubMed

    Valette, H; Bottlaender, M; Dollé, F; Guenther, I; Coulon, C; Hinnen, F; Fuseau, C; Ottaviani, M; Crouzel, C

    1999-01-01

    The biodistribution of the nicotinic acetylcholine receptor (nAChR) radioligand 2-[18F]fluoro-3-[2(S)-2-azetidinylmethoxy]pyridine ([18F]fluoro-A-85380, half-life of fluorine-18 = 110 min) in selected rat brain areas was assessed in vivo. The radiotracer showed a good penetration in the brain. The regional distribution of the radioligand was consistent with the density of nAChRs determined from previous studies in vitro. Sixty minutes post-injection, the highest uptake was observed in the thalamus, (1% I.D./g tissue), an intermediate one in the frontal cortex (0.78% I.D./g tissue), and the lowest in the cerebellum (0.5% I.D./g tissue). Pretreatment with several nAChR ligands (nicotine, cytisine, epibatidine, unlabeled fluoro-A-85380) substantially reduced uptake of the radioligand in the three cerebral areas. Pretreatment with the nAChR channel blocker mecamylamine or with the muscarinic receptor antagonist dexetimide had no appreciable effect on the uptake of fluoro-A-85380. These results support the high in vivo selectivity and specificity of fluoro-A-85380. Therefore, [18F]fluoro-A-85380 may be useful for positron emission tomography study of nAChRs in humans. PMID:10072197

  1. Density functional theory of the CuA -like Cu2 S2 diamond core in Cu 2II(NGuaS)2 Cl2.

    PubMed

    Witte, M; Gerstmann, U; Neuba, A; Henkel, G; Schmidt, W G

    2016-04-30

    Density functional theory (DFT) calculations with localized as well as plane-wave basis functions are performed for the recently reported dicopper thiolate species Cu2 (NGuaS)2 Cl2 [NGuaS = 2-(1,1,3,3-tetramethylguanidino) benzenethiolate, C11 H16 N3 S] and its bromo derivative [Neuba et al., Angew. Chem. Int. Ed. 2012, 51, 1714.]. For both hybrid and semilocal functionals, the neutral complexes are found to have broken symmetry (BS) character, with electron paramagnetic resonance silent, antiferromagnetically coupled [Cu(2+) …Cu(2+) ] site in which the coupling is driven by super exchange interaction within the Cu2 S2 diamond core. The accurate theoretical description of the geometric structure, however, provides a major challenge for DFT: (i) the multideterminant character of the ground state wave function has to be covered by the BS approach. It requires (ii) metageneralized gradient approximations, that is hybrid functionals with an explicit dependence on the kinetic energy of the individual orbitals: In combination with a dispersion correction, the metafunctional TPSSh results in a CuCu distance close to the experimentally observed value of 2.7 Å. For the negative charge state of the complex, a mixed-valent [Cu(1.5+) …Cu(1.5+) ] electronic structure with a smaller CuCu distance of 2.6 Å is predicted, similar to the value of the CuA site of cytochrome c oxidase. © 2016 Wiley Periodicals, Inc. PMID:26804007

  2. Observation of transitions in lithiumlike germanium

    NASA Technical Reports Server (NTRS)

    Behring, W. E.; Seely, J. F.; Brown, C. M.; Feldman, U.; Knauer, J. P.

    1989-01-01

    Transitions of the type n = 2-2, n = 2-3 and n = 3-4 in Li-like Ge(29+) have been observed in the spectrum from a laser-produced plasma. The energy levels and ionization energy of Ge(29+) were derived from the observed wavelengths. The wavelength of the 2s 2S1/2-2p 2P3/2 transition is sufficiently accurate to determine the quantum-electrodynamic contribution to the transition energy.

  3. Energies and spin states of FeS(0/-), FeS2(0/-), Fe2S2(0/-), Fe3S4(0/-), and Fe4S4(0/-) clusters.

    PubMed

    Li, Yan-Ni; Wang, Shengguang; Wang, Tao; Gao, Rui; Geng, Chun-Yu; Li, Yong-Wang; Wang, Jianguo; Jiao, Haijun

    2013-04-15

    The structures and energies of the electronic ground states of the FeS(0/-), FeS2(0/-), Fe2S2(0/-), Fe3S4(0/-), and Fe4S4(0/-) neutral and anionic clusters have been computed systematically with nine computational methods in combination with seven basis sets. The computed adiabatic electronic affinities (AEA) have been compared with available experimental data. Most reasonable agreements between theory and experiment have been found for both hybrid B3LYP and B3PW91 functionals in conjugation with 6-311+G* and QZVP basis sets. Detailed comparisons between the available experimental and computed AEA data at the B3LYP/6-311+G* level identified the electronic ground state of (5)Δ for FeS, (4)Δ for FeS(-), (5)B2 for FeS2, (6)A1 for FeS2(-), (1)A1 for Fe2S2, (8)A' for Fe2S2(-), (5)A'' for Fe3S4, (6)A'' for Fe3S4(-), (1)A1 for Fe4S4, and (1)A2 for Fe4S4(-). In addition, Fe2S2, Fe3S4, Fe3S4(-), Fe4S4, and Fe4S4(-) are antiferromagnetic at the B3LYP/6-311+G* level. The magnetic properties are discussed on the basis of natural bond orbital analysis. PMID:23471871

  4. Laser gain on 3p-3d and 3s-3p transitions and X-ray line ratios for the nitrogen isoelectronic sequence

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Seely, J. F.; Bhatia, A. K.

    1989-01-01

    Results are presented on calculations of the 72 levels belonging to the 2s(2)2p(3), 2s2p(4), 2p(5), 2s(2)2p(2)3s, 2s(2)2p(2)3p, and 2s(2)2p(2)3d configurations of the N I isoelectronic sequence for the ions Ar XII, Ti XVI, Fe XX, Zn XXIV, and Kr XXX, for electron densities up to 10 to the 24th/cu cm. It was found that large population inversions and gain occur between levels in the 2s(2)2p(2)3p configuration and levels in the 2s(2)2p(2)3d configuration that cannot decay to the ground configuration by an electric dipole transition. For increasing electron densities, the intensities of the X-ray transitions from the 2s(2)2p(2)3p configuration to the ground configuration decrease relative to the transitions from the 2s(2)2p(2)3s and 2s(2)2p(2)3d configurations to the ground configuration. The density dependence of these X-ray line ratios is presented.

  5. Lifetime for Li-like Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level using a mode of beam-two-foil experiments

    SciTech Connect

    Nandi, T.; Ahmad, Nissar; Wani, A.A.

    2005-08-15

    The option of varying thickness of the fixed foil in the beam-two-foil technique has been incorporated in our experimental setup. It gives an opportunity to explore a new mode of this technique. In the current study, we have investigated the lifetime of the 1s2s2p {sup 4}P{sub 5/2}{sup o} level in Li-like titanium using this technique. The data showed a dependence of foil thickness of the fixed foil on the interactions of levels produced in the first foil. Average lifetime obtained for the Li-like titanium 1s2s2p {sup 4}P{sub 5/2}{sup o} level (200{+-}12 ps) is compared very well with the earlier theoretical and experimental values.

  6. [Preparation of Cu/ZrO2/S2O8(2-)/gamma-Al2O3 solid acid catalyst and its catalytic activity to selective reduction of NO].

    PubMed

    Guo, Xi-kun; Wang, Xiao-ming

    2008-06-01

    Cu/ZrO2/S2O8(2-)/gamma-Al2O3 solid acid catalyst was prepared by loading of (NH4)2S2O8, ZrOCl2, and Cu(NO3)2 onto gamma-Al2O3 step by step, which was obtained from calcining of pseudoboehmite. The catalytic property of Cu/ZrO2/S2O8(2-)/gamma-Al2O3 on the selective reduction of NO by C3H6 in excess oxygen was investigated. The relationship between the structure and the catalytic property of Cu/ZrO2/S2O8(2-)/gamma-Al2O3 catalyst was also explored by means of SEM, XRD, Py-IR and TPR. The experimental results of catalytic activity of the title catalyst indicated that the maximum conversion rate of NO could reach 82.9% in the absence of water and was up to 80.2% even in the presence of 10% water vapor. The results of the structural characterization toward the catalyst showed that S2O8(2-) and ZrO2 could restrain the sinteration of gamma-Al2O3 particles and the formation of CuAl2O4 spinelle, and also facilitate the formation of new acidic sites (Brönsted acid) and the enhance of the acidity on the surface of the catalyst. In addition, ZrO2 could increase the reducibility of Cu on the catalyst. Consequently, the catalytic activity and hydrothermal stability of the catalyst were improved effectively. PMID:18763532

  7. Monothiol Glutaredoxins Can Bind Linear [Fe3S4]+ and [Fe4S4]2+ Clusters in Addition to [Fe2S2]2+ Clusters: Spectroscopic Characterization and Functional Implications

    PubMed Central

    Zhang, Bo; Bandyopadhyay, Sibali; Shakamuri, Priyanka; Naik, Sunil G.; Huynh, Boi Hanh; Couturier, Jérémy; Rouhier, Nicolas; Johnson, Michael K.

    2013-01-01

    Saccharomyces cerevisiae mitochondrial glutaredoxin 5 (Grx5) is the archetypical member of a ubiquitous class of monothiol glutaredoxins with a strictly conserved CGFS active-site sequence that has been shown to function in biological [Fe2S2]2+ cluster trafficking. In this work, we show that recombinant S. cerevisiae Grx5 purified aerobically after prolonged exposure of the cell-free extract to air or after anaerobic reconstitution in the presence of glutathione, predominantly contains a linear [Fe3S4]+ cluster. The excited state electronic properties and ground state electronic and vibrational properties of the linear [Fe3S4]+ cluster have been characterized using UV-visible absorption/CD/MCD, EPR, Mössbauer and resonance Raman spectroscopies. The results reveal a rhombic S = 5/2 linear [Fe3S4]+ cluster with properties similar to those reported for synthetic linear [Fe3S4]+ clusters and the linear [Fe3S4]+ clusters in purple aconitase. Moreover, the results indicate that the Fe-S cluster content previously reported for many monothiol Grxs has been misinterpreted exclusively in terms of [Fe2S2]2+ clusters, rather than linear [Fe3S4]+ clusters or mixtures of linear [Fe3S4]+ and [Fe2S2]2+ clusters. In the absence of GSH, anaerobic reconstitution of Grx5 yields a dimeric form containing one [Fe4S4]2+ cluster that competent for in vitro activation of apo-aconitase, via intact cluster transfer. The ligation of the linear [Fe3S4]+ and [Fe4S4]2+ clusters in Grx5 has been assessed by spectroscopic, mutational and analytical studies. Potential roles for monothiol Grx5 in scavenging and recycling linear [Fe3S4]+ clusters released during protein unfolding under oxidative stress conditions and in maturation of [Fe4S4]2+ cluster-containing proteins are discussed in light of these results. PMID:24032439

  8. Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2](-): structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes.

    PubMed

    Thirumoorthi, Ramalingam; Chivers, Tristram; Häggman, Susanna; Mansikkamäki, Akseli; Morgan, Ian S; Tuononen, Heikki M; Lahtinen, Manu; Konu, Jari

    2016-08-01

    A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctly different Ni-S bond lengths (2.3487(8), 2.4500(9) and 2.5953(10) Å). By contrast, in the red-brown square-planar complex 5b the two ligands are S,S'-chelated to Ni(ii) (d(Ni-S) = 2.165(2) and 2.195(2) Å) with one pendant PPh2S group. DFT calculations revealed that the energetic difference between singlet and triplet state octahedral and square-planar isomers of the Ni(ii) complex is essentially indistinguishable. Consistently, VT and (31)P CP/MAS NMR spectroscopic investigations indicated that a mixture of isomers exists in solution at room temperature, while the singlet state square-planar isomer 5b becomes favoured at -40 °C. PMID:27453403

  9. Reliable measurement of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetime by beam-foil and beam-two-foil experiments

    SciTech Connect

    Nandi, T.; Ahmad, Nissar; Wani, A. A.; Marketos, P.

    2006-03-15

    We have determined the lifetime of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level (210.5{+-}13.5 ps) using data from its x-ray decay channel through beam single- and two-foil experiments, coupled to a multicomponent iterative growth and decay analysis. Theoretical lifetime estimates for this zero-nuclear-spin ion lies within the uncertainty range of our experimental results, indicating that blending contributions to this level from the He-like 1s2p {sup 3}P{sub 2}{sup o} and 1s2s {sup 3}S{sub 1} levels are eliminated within the current approach. A previously reported discrepancy between experimental and theoretical 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetimes in {sub 23}{sup 51}V may, as a result, be attributed to hyperfine quenching.

  10. Disilicon complexes with two hexacoordinate Si atoms: paddlewheel-shaped isomers with (ClN4 )Si-Si(S4 Cl) and (ClN2 S2 )Si-Si(S2 N2 Cl) skeletons.

    PubMed

    Wagler, Jörg; Brendler, Erica; Heine, Thomas; Zhechkov, Lyuben

    2013-10-11

    The reaction of 1-methyl-3-trimethylsilylimidazoline-2-thione with hexachlorodisilane proceeds toward substitution of four of the disilane Cl atoms during the formation of disilicon complexes with two neighboring hexacoordinate Si atoms. The N,S-bidentate methimazolide moieties adopt a buttressing role, thus forming paddlewheel-shaped complexes of the type ClSi(μ-mt)4 SiCl (mt=methimazolyl). Most interestingly, three isomers (i.e., with (ClN4 )SiSi(S4 Cl), (ClN3 S)SiSi(S3 NCl), and (ClN2 S2 )SiSi(S2 N2 Cl) skeletons as so-called (4,0), (3,1), and cis-(2,2) paddlewheels) were detected in solution by using (29) Si NMR spectroscopic analysis. Two of these isomers could be isolated as crystalline solids, thus allowing their molecular structures to be analyzed by using X-ray diffraction studies. In accord with time-dependent NMR spectroscopy, computational analyses proved the cis-(2,2) isomer with a (ClN2 S2 )SiSi(S2 N2 Cl) skeleton to be the most stable. The compounds presented herein are the first examples of crystallographically evidenced disilicon complexes with two SiSi-bonded octahedrally coordinated Si atoms and representatives of the still scarcely explored class of Si coordination compounds with sulfur donor atoms. PMID:24009095

  11. Probing Variable Amine/Amide Ligation in NiIIN2S2 Complexes Using Sulfur K-Edge and Nickel L-Edge X-ray Absorption Spectroscopies: Implications for the Active Site of Nickel Superoxide Dismutase

    SciTech Connect

    Shearer,J.; Dehestani, A.; Abanda, F.

    2008-01-01

    Nickel superoxide dismutase (NiSOD) is a recently discovered metalloenzyme that catalyzes the disproportionation of O2* into O2 and H2O2. In its reduced state, the mononuclear NiII ion is ligated by two cis-cysteinate sulfurs, an amine nitrogen (from the protein N-terminus), and an amide nitrogen (from the peptide backbone). Unlike many small molecule and metallopeptide-based NiN2S2 complexes, S-based oxygenation is not observed in NiSOD. Herein we explore the spectroscopic properties of a series of three NiIIN2S2 complexes (bisamine-ligated (bmmp-dmed)NiII, amine/amide-ligated (NiII(BEAAM)), and bisamide-ligated (NiII(emi))2) with varying amine/amide ligation to determine the origin of the dioxygen stability of NiSOD. Ni L-edge X-ray absorption spectroscopy (XAS) demonstrates that there is a progression in ligand-field strength with (bmmp-dmed)NiII having the weakest ligand field and (NiII(emi)2) having the strongest ligand field. Furthermore, these Ni L-edge XAS studies also show that all three complexes are highly covalent with (NiII(BEEAM)) having the highest degree of metal-ligand covalency of the three compounds studied. S K-edge XAS also shows a high degree of NiS covalency in all three complexes. The electronic structures of the three complexes were probed using both hybrid-DFT and multiconfigurational SORCI calculations. These calculations demonstrate that the nucleophilic Ni(3d)/S()* HOMO of these NiN2S2 complexes progressively decreases in energy as the amide-nitrogens are replaced with amine nitrogens. This decrease in energy of the HOMO deactivates the Ni-center toward O2 reactivity. Thus, the NiS bond is protected from S-based oxygenation explaining the enhanced stability of the NiSOD active-site toward oxygenation by dioxygen.

  12. O1, P1, N2 models of the global ocean tide on an elastic earth plus surface potential and spherical harmonic decompositions for M2, S2, and K1

    NASA Technical Reports Server (NTRS)

    Parke, M. E.

    1982-01-01

    The models of M2, S2, and K1 presented in Parke and Hendershott (1980) are supplemented with models of O1, P1, and N2. The models satisfy specified elevation boundary conditions and are generated by fighting a small number of test functions to island data. Maps are presented of the geocentric tide, the induced free space potential, the induced vertical component of the solid earth tide, and the induced vertical component of the gravitational field for each new component. Maps of the tidal potential seen by an observer fixed to the surface of the solid earth are also presented for all six constituents. Spherical harmonic coefficients up to order four and the rms magnitude of the coefficients to order fifteen are presented for each constituent. The rms magnitudes of the P1 and K1 coefficients normalized by their respective equilibrium amplitudes are compared to determine the effect of the diurnal core resonance.

  13. [Degradation of orange IV dye solution catalyzed by Fe (NO3)3-(NH4)2S2O8 modified GAC in the presence of H2O2].

    PubMed

    Zhang, Ying-Jie; Xu, Shu-Fen; Liao, Xia; Cao, Tian-Jing; Yang, Rong; Li, Da-Peng

    2012-10-01

    This study was designed to investigate the catalytic oxidation performance of modified GAC by Fe(NO3), and (NH4)2S2O8 in the process of H2O2. The effect of the initial concentration of H2O2, initial dye concentration, catalyst dosage, initial pH and temperature on the reaction was discussed. The results show that the catalyst of Fe/S/GAC has a better catalytic reactivity to decompose Orange IV compared with that of Fe/GAC. The catalyst could decompose H2O2 to degrade Orange IV effectively at pH 2.4-9.1. The removal rate of Orange IV increased with the increase of catalyst dosage. With the decrease of dye concentration, the reaction rate became faster, this reaction followed the second-order reaction kinetics with activation energy (Ea) of 68.19 kJ x mol(-1). Reuse of catalyst did not decrease the removal rate. Orange IV degradation mainly followed OH mechanism. PMID:23233975

  14. Wet oxidation of ordered mesoporous carbon FDU-15 by using (NH4)2S2O8 for fast adsorption of Sr(II): An investigation on surface chemistry and adsorption mechanism

    NASA Astrophysics Data System (ADS)

    Song, Yang; Ye, Gang; Chen, Jing; Lv, Dachao; Wang, Jianchen

    2015-12-01

    Surface modification of ordered mesoporous carbon (OMC) by wet oxidation provides an oxygen-enriched platform for complexation of metal ions. Here, we present a comprehensive study on the surface chemistry and textual property of OMC FDU-15 modified by wet oxidation using (NH4)2S2O8 as a benign oxidant. And, for the first time, the adsorption behavior and mechanism of wet-oxidized OMC FDU-15 toward Sr(II) in aqueous solutions were investigated. The mesostructural regularity of the OMC FDU-15 was well-reserved under wet oxidation. Compared to OMC CMK-type counterparts prepared via nanocasting, the OMC FDU-15 by soft template method showed much-enhanced structural stability. Due to the introduction of abundant oxygen-containing species, the oxidized OMC FDU-15 exhibited excellent hydrophilicity and dispersibility in aqueous solutions. The adsorption behavior toward Sr(II) was fully investigated, showing a super-fast adsorption kinetics (< 5 min to reach equilibrium) and a Langmuir adsorption isotherm. Moreover, an in-depth X-ray photoelectron spectroscopy analysis through deconvolution of high resolution C1s and O1s spectra was implemented to identify the chemical species of the surface functional groups, while probing the adsorption mechanism. The results suggested that oxygen donor atoms in Csbnd O single bonds mainly contribute to the adsorption of Sr(II) via formation of metal-ligand complexation.

  15. Pharmacological profile of novel acid pump antagonist 7-(4-fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methyl cyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526).

    PubMed

    Ito, Keiichi; Kinoshita, Kazuya; Tomizawa, Atsuyuki; Inaba, Fumi; Morikawa-Inomata, Yuka; Makino, Mitsuko; Tabata, Keiichi; Shibakawa, Nobuhiko

    2007-10-01

    The pharmacological profiles of the novel acid pump antagonist 7-(4-fluorobenzyloxy)-2,3-dimethyl-1-{[(1S,2S)-2-methylcyclopropyl]methyl}-1H-pyrrolo[2,3-d]pyridazine (CS-526) were investigated in terms of hog gastric H+,K+-ATPase activity, gastric acid secretion, and acute gastroesophageal lesions in comparison with other proton pump inhibitors (PPIs). CS-526 inhibited H+,K+-ATPase activity in a concentration-dependent manner, with an IC50 value of 61 nM. The inhibitory effect of CS-526 on H+,K+-ATPase activity was more potent than that of any of the other PPIs examined. The inhibitory mechanism of CS-526 on H+,K+-ATPase was a competitive antagonism to the K+ binding site of H+,K+-ATPase, and it was also a reversible inhibition. In pylorus-ligated rats, intraduodenal or oral administration of CS-526 inhibited gastric acid secretion in a dose-dependent manner, and the ID50 values were 2.8 or 0.7 mg/kg, respectively. In Heidenhain pouch dogs, intrapouch administration of CS-526 inhibited histamine-stimulated gastric acid secretion in a dose- and retention time-dependent manner. In a reflux esophagitis model, intraduodenal and oral administration of CS-526 prevented esophageal lesions with ID50 values of 5.4 and 1.9 mg/kg, respectively. Lansoprazole prevented esophagitis only by intraduodenal administration (ID50 = 2.2 mg/kg). Furthermore, CS-526 inhibited acute gastric mucosal lesions. These data demonstrate that the novel acid pump antagonist CS-526 has potent antisecretory and antiulcer effects. These findings indicate that CS-526 would have a curative effect on gastroesophageal reflux disease via its potent antisecretory and antiulcer actions. PMID:17630360

  16. Identification of produced powerful radicals involved in the mineralization of bisphenol A using a novel UV-Na(2)S(2)O(8)/H(2)O(2)-Fe(II,III) two-stage oxidation process.

    PubMed

    Huang, Yi-Fong; Huang, Yao-Hui

    2009-03-15

    A two-stage oxidation (UV-Na(2)S(2)O(8)/H(2)O(2)-Fe(II,III)) process was applied to mineralize bisphenol A (BPA) at pH(i) (initial pH) 7. We take advantage of the high oxidation potential of sulfate radicals and use persulfate as the 1st-stage oxidant to oxidize BPA to less complex compounds (stoichiometric ratio: [S(2)O(8)(2-)](0)/[BPA](0)=1). Afterwards, the traditional photo-Fenton process was used to mineralize those compounds to CO(2). To the best of our knowledge, this is the first attempt to utilize the two processes in conjunction for the complete degradation of BPA. During the 2nd-stage reaction, other oxidants (H(2)O(2) and Iron alone) were also employed to observe the extent of enhancement of photo-Fenton. Further, qualitative identification of both hydroxyl and sulfate radicals was performed to evaluate their dominance under different conditions. The BPA degradation in this UV/persulfate process formulated a pseudo-first-order kinetic model well, with a rate constant of approximately 0.038 min(-1) (25 degrees C), 0.057 min(-1) (35 degrees C), and 0.087 min(-1) (50 degrees C), respectively. The much lower activation energy (DeltaE = 26 kJ mol(-1)) was further calculated to clarify that the thermal-effect of an illuminated system differs from single heat-assisted systems described in other research. Final total organic carbon (TOC) removal levels of BPA by the use of such two-stage oxidation processes were 25-34%, 25%, and 87-91% for additional Fe(II,III) activation, H(2)O(2) promotion, and Fe(II,III)/H(2)O(2) promotions, respectively. PMID:18635314

  17. Vibrational assignment, HOMO-LUMO and NBO analysis of (2S)-2-[(2-{[(2S)-1-hydroxybutan-2-yl]amino}ethyl)amino]butan-1-ol by density functional theory

    NASA Astrophysics Data System (ADS)

    Rajalakshmi, K.; Gunasekaran, S.; Kumaresan, S.

    2014-09-01

    The FTIR and FT-Raman spectra of (2S)-2-[(2-{[(2S)-1-hydroxybutan-2-yl]amino}ethyl)amino]butan-1-ol have been recorded in the region 4000-400 cm-1and 4000-100 cm-1 respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental vibrational modes of the compound were carried out. The optimized molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering were calculated by HF and density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) quantum chemical method with 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p) basis sets. The theoretical and optimized geometric parameters and vibrational frequencies have been found in good agreement with the corresponding experimental data and results in the literature. Ultraviolet-visible spectrum of the title molecule was recorded and has been calculated using TD-DFT method. The first-order hyperpolarizability (βo) and other related properties (μ, αo) of the compound are calculated using DFT method on a finite field approach. The most stable geometry of the compound under investigation has been determined from the potential energy scan. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital analysis (NBO). Besides, molecular electrostatic potential (MESP), HOMO and LUMO analysis, Mulliken population analysis and several other thermodynamic properties were performed by HF and DFT method.

  18. Vibrational assignment, HOMO-LUMO and NBO analysis of (2S)-2-[(2-{[(2S)-1-hydroxybutan-2-yl]amino}ethyl)amino]butan-1-ol by density functional theory.

    PubMed

    Rajalakshmi, K; Gunasekaran, S; Kumaresan, S

    2014-09-15

    The FTIR and FT-Raman spectra of (2S)-2-[(2-{[(2S)-1-hydroxybutan-2-yl]amino}ethyl)amino]butan-1-ol have been recorded in the region 4000-400 cm(-1)and 4000-100 cm(-1) respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental vibrational modes of the compound were carried out. The optimized molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering were calculated by HF and density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) quantum chemical method with 6-31G(d,p), 6-31+G(d,p), 6-31++G(d,p) basis sets. The theoretical and optimized geometric parameters and vibrational frequencies have been found in good agreement with the corresponding experimental data and results in the literature. Ultraviolet-visible spectrum of the title molecule was recorded and has been calculated using TD-DFT method. The first-order hyperpolarizability (βo) and other related properties (μ, αo) of the compound are calculated using DFT method on a finite field approach. The most stable geometry of the compound under investigation has been determined from the potential energy scan. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital analysis (NBO). Besides, molecular electrostatic potential (MESP), HOMO and LUMO analysis, Mulliken population analysis and several other thermodynamic properties were performed by HF and DFT method. PMID:24813275

  19. X-ray Absorption and Emission Spectroscopic Studies of [L2Fe2S2](n) Model Complexes: Implications for the Experimental Evaluation of Redox States in Iron-Sulfur Clusters.

    PubMed

    Kowalska, Joanna K; Hahn, Anselm W; Albers, Antonia; Schiewer, Christine E; Bjornsson, Ragnar; Lima, Frederico A; Meyer, Franc; DeBeer, Serena

    2016-05-01

    Herein, a systematic study of [L2Fe2S2](n) model complexes (where L = bis(benzimidazolato) and n = 2-, 3-, 4-) has been carried out using iron and sulfur K-edge X-ray absorption (XAS) and iron Kβ and valence-to-core X-ray emission spectroscopies (XES). These data are used as a test set to evaluate the relative strengths and weaknesses of X-ray core level spectroscopies in assessing redox changes in iron-sulfur clusters. The results are correlated to density functional theory (DFT) calculations of the spectra in order to further support the quantitative information that can be extracted from the experimental data. It is demonstrated that due to canceling effects of covalency and spin state, the information that can be extracted from Fe Kβ XES mainlines is limited. However, a careful analysis of the Fe K-edge XAS data shows that localized valence vs delocalized valence species may be differentiated on the basis of the pre-edge and K-edge energies. These findings are then applied to existing literature Fe K-edge XAS data on the iron protein, P-cluster, and FeMoco sites of nitrogenase. The ability to assess the extent of delocalization in the iron protein vs the P-cluster is highlighted. In addition, possible charge states for FeMoco on the basis of Fe K-edge XAS data are discussed. This study provides an important reference for future X-ray spectroscopic studies of iron-sulfur clusters. PMID:27097289

  20. Oscillator strengths and transition probabilities for allowed and forbidden transitions in Fe XIX

    SciTech Connect

    Nahar, Sultana N.

    2011-07-15

    An extensive set of oscillator strengths, line strengths, and radiative decay rates for the allowed and forbidden transitions in Fe XIX is presented. They correspond to 1626 fine structure levels of total angular momenta 0{<=}J{<=}8 of even and odd parities with 2{<=}n{<=}10, 0{<=}l{<=}9, 0{<=}L{<=}10, and (2S+1)=1, 3, 5. In contrast, the compiled table of the National Institute for Standards and Technology (NIST) lists only 63 observed levels. A total of 289,291 electric dipole allowed transitions are presented. They were obtained in the close coupling approximation using the relativistic Breit-Pauli R-matrix method. The wavefunction expansion included 15 levels of the configurations 2s{sup 2}2p{sup 3}, 2s2p{sup 4}, and 2p{sup 5} of the Fe XX core. The calculated fine structure levels are assigned with spectroscopic identifications using quantum defect analysis. Comparison with the observed energies shows very good agreement, the largest difference being less than 4%. The transitions also compare well with the compiled data by NIST and recent calculations. The forbidden transitions of the electric quadrupole and octupole, and magnetic dipole and quadrupole, type are presented for the 379 levels of the configurations 2s{sup 2}2p{sup 4}, 2s2p{sup 5}, 2p{sup 6}, 2s{sup 2}2p{sup 3}3s, 2s{sup 2}2p{sup 3}3p, 2s{sup 2}2p{sup 3}3d, 2s{sup 2}2p{sup 3}4s, 2s{sup 2}2p{sup 3}4p, 2s{sup 2}2p{sup 3}4d, 2s{sup 2}2p{sup 3}4f, 2s2p{sup 4}3s, 2s2p{sup 4}3p, 2s2p{sup 4}3d, 2s2p{sup 4}4s, 2s2p{sup 4}4p, and 2s{sup 2}2p{sup 2}3s{sup 2} of Fe XIX. They correspond to a total of 66,619 transitions. These results have been obtained from relativistic Breit-Pauli atomic structure calculations using the program SUPERSTRUCTURE. The forbidden transition probabilities show very good agreement with those compiled by NIST. - Highlights: {yields} Presents the most complete (n up to 10) set of transitions for Fe XIX. {yields} Considers both allowed and forbidden transitions. {yields} Large number

  1. Polarizabilities of the beryllium clock transition

    SciTech Connect

    Mitroy, J.

    2010-11-15

    The polarizabilities of the three lowest states of the beryllium atom are determined from a large basis configuration interaction calculation. The polarizabilities of the 2s{sup 2} {sup 1}S{sup e} ground state (37.73a{sub 0}{sup 3}) and the 2s2p {sup 3}P{sub 0}{sup o} metastable state (39.04a{sub 0}{sup 3}) are found to be very similar in size and magnitude. This leads to an anomalously small blackbody radiation shift at 300 K of -0.018(4) Hz for the 2s{sup 2} {sup 1}S{sup e}-2s2p {sup 3}P{sub 0}{sup o} clock transition. Magic wavelengths for simultaneous trapping of the ground and metastable states are also computed.

  2. Spectroscopy of berylliumlike xenon ions using dielectronic recombination

    NASA Astrophysics Data System (ADS)

    Bernhardt, D.; Brandau, C.; Harman, Z.; Kozhuharov, C.; Böhm, S.; Bosch, F.; Fritzsche, S.; Jacobi, J.; Kieslich, S.; Knopp, H.; Nolden, F.; Shi, W.; Stachura, Z.; Steck, M.; Stöhlker, Th; Schippers, S.; Müller, A.

    2015-07-01

    Be-like 136X{{e}50+} ions have been investigated employing the resonant electron-ion collision process of dielectronic recombination (DR) as a spectroscopic tool. The experiments were performed at the experimental storage ring in Darmstadt, Germany, using its electron cooler as a target for free electrons. DR Rydberg resonance series 2{{s}2}+{{e}-}\\to 2s2{{p}{{j\\prime }}}n{{l}j} for the associated intra-L-shell transitions 2{{s}2}{{ }1}{{S}0}-2s2{{p}1/2}{{ }3}{{P}1},2{{s}2}{{ }1}{{S}0}-2s2{{p}3/2}{{ }3}{{P}2} and 2{{s}2}{{ }1}{{S}0}-2s2{{p}3/2}{{ }1}{{P}1} were observed with high resolution. In addition to these excitations from the ground state we determined resonances associated with excitations 2s2{{p}1/2}{{ }3}{{P}0}\\to 2{{p}1/2}2{{p}3/2}{{ }3}{{P}1} of ions initially in the metastable 2s2{{p}1/2}{{ }3}{{P}0} state. The corresponding excitation energies were determined to be E{{(}1}{{S}0}\\to {{ }3}{{P}1})=127.269(46) eV, E{{(}1}{{S}0}\\to {{ }3}{{P}2})=469.474(81) eV and E{{(}1}{{S}0}\\to {{ }1}{{P}1})=532.801(16) eV, and E{{(}3}{{P}0}\\to 2{{p}1/2}2{{p}3/2}{{ }3}{{P}1})=533.733(22) eV. These excitation energies are compared with previous measurements and with recent state-of-the-art atomic structure calculations.

  3. Transition Planning

    ERIC Educational Resources Information Center

    Statfeld, Jenna L.

    2011-01-01

    Post-school transition is the movement of a child with disabilities from school to activities that occur after the completion of school. This paper provides information about: (1) post-school transition; (2) transition plan; (3) transition services; (4) transition planning; (5) vocational rehabilitation services; (6) services that are available…

  4. Direct loading of a large Yb MOT on the {}^{1}{{\\rm{S}}}_{0}\\;\\to {}^{3}{{\\rm{P}}}_{1} transition

    NASA Astrophysics Data System (ADS)

    Guttridge, A.; Hopkins, S. A.; Kemp, S. L.; Boddy, D.; Freytag, R.; Jones, M. P. A.; Tarbutt, M. R.; Hinds, E. A.; Cornish, S. L.

    2016-07-01

    We report a robust technique for laser frequency stabilisation that enables the reproducible loading of in excess of 109 Yb atoms from a Zeeman slower directly into a magneto-optical trap (MOT) operating on the {}1{{{S}}}0\\to {}3{{{P}}}1 transition, without the need for a first stage MOT on the {}1{{{S}}}0\\to {}1{{{P}}}1 transition. We use a simple atomic beam apparatus to generate narrow fluorescence signals on both the 399 nm {}1{{{S}}}0\\to {}1{{{P}}}1 transition used for the Zeeman slower and the 556 nm {}1{{{S}}}0\\to {}3{{{P}}}1 transition. We present in detail the methods for obtaining spectra with a high signal-to-noise ratio and demonstrate error signals suitable for robust frequency stabilisation. Finally we demonstrate the stability and precision of our technique through sensitive measurements of the gravitational sag of the Yb MOT as a function of the intensity of the laser cooling beams, which are in good agreement with theory. These results will be important for efficient loading of the atoms into an optical dipole trap.

  5. Storage-ring measurements of hyperfine induced transition rates in berylliumlike ions

    SciTech Connect

    Schippers, Stefan

    2013-07-11

    The status of experimental measurements and theoretical calculations of the hyperfine induced 2s2p{sup 3}P{sub 0}{yields}2s{sup 21}S{sub 0} transition rate in Be-like ions is reviewed. Possible reasons, such as external electromagnetic fields and competing E1M1 two-photon transitions, for presently existing significant discrepancies between experiment and theory are discussed. Finally, directions for future research are outlined.

  6. Accurate transition rates for intercombination lines of singly ionized nitrogen

    SciTech Connect

    Tayal, S. S.

    2011-01-15

    The transition energies and rates for the 2s{sup 2}2p{sup 2} {sup 3}P{sub 1,2}-2s2p{sup 3} {sup 5}S{sub 2}{sup o} and 2s{sup 2}2p3s-2s{sup 2}2p3p intercombination transitions have been calculated using term-dependent nonorthogonal orbitals in the multiconfiguration Hartree-Fock approach. Several sets of spectroscopic and correlation nonorthogonal functions have been chosen to describe adequately term dependence of wave functions and various correlation corrections. Special attention has been focused on the accurate representation of strong interactions between the 2s2p{sup 3} {sup 1,3}P{sub 1}{sup o} and 2s{sup 2}2p3s {sup 1,3}P{sub 1}{sup o}levels. The relativistic corrections are included through the one-body mass correction, Darwin, and spin-orbit operators and two-body spin-other-orbit and spin-spin operators in the Breit-Pauli Hamiltonian. The importance of core-valence correlation effects has been examined. The accuracy of present transition rates is evaluated by the agreement between the length and velocity formulations combined with the agreement between the calculated and measured transition energies. The present results for transition probabilities, branching fraction, and lifetimes have been compared with previous calculations and experiments.

  7. Cross sections and rate coefficients for excitation of Δn = 1 transitions in Li-like ions with 6 < Z < 42.

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Safronova, M. S.; Kato, T.

    Excitation cross sections and rate coefficients by electron impact were calculated for the 1s22s - 1s2s2p, 1s22s - 1s2s2 and 1s22s - 1s2p2 transitions of the Li-like ions (C IV, N V, O VI, Ne VIII, Mg X, Al XI, Si XII, S XIV, Ar XVI, Ca XVIII, Ti XX, Fe XXIV, Ni XXVI, Zn XXVIII, Ge XXX, Se XXXII, Kr XXXIIV and Mo XXXX) by a Coulomb-Born approximation with exchange and including relativistic effects and configuration interactions. Level energies, mixing coefficients and transition wavelengths and probabilities were also computed.

  8. Be I isoelectronic ions embedded in hot plasma.

    PubMed

    Saha, B; Fritzsche, S

    2006-03-01

    The influence of plasma screening on the 2s(2 1)S0-->2s2p(3)p(0)1 intercombination and the 2s(2 1)S0-->2s2p(1)p(0)1 allowed transitions is investigated theoretically for several ions along the isoelectronic sequence (C III, N IV, O V, Si XI, Fe XXIII, and Mo XXXIX). For the case of a weakly coupled hot plasma, multiconfiguration Dirac-Fock computations have been carried out for these ions by considering a (time averaged) Debye-Hückel potential for both the "electron-nucleus" and "electron-electron" interaction. The plasma screening is found to enlarge the 2s(2 1)S0-->2s2p(3)p(0)1 excitation energy uniformly along the Be I isoelectronic sequence, leading to an increasing blueshift of this intercombination line as the nuclear charge is increased. For the 2s(2 1)S0-->2s2p(1)p(0)1 resonance line, in contrast, the transition energy is either blueshifted or redshifted in dependence of the screening parameter and owing to a cancellation of the plasma screening on the electron-nucleus and electron-electron interaction. This interplay of the (external) plasma screening with the internal interactions in the berylliumlike ions leads, for instance, to a shift of the resonance transition from red to blue in going from O V to Si XI ions. Apart from the screening effects on the transition energies, we also investigate their influence on the oscillator strengths and emission rates along the Be I isoelectronic sequence. PMID:16605666

  9. Absolute frequency measurements and hyperfine structures of the molecular iodine transitions at 578 nm

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takumi; Akamatsu, Daisuke; Hosaka, Kazumoto; Inaba, Hajime; Okubo, Sho; Tanabe, Takehiko; Yasuda, Masami; Onae, Atsushi; Hong, Feng-Lei

    2016-04-01

    We report absolute frequency measurements of 81 hyperfine components of the rovibrational transitions of molecular iodine at 578 nm using the second harmonic generation of an 1156-nm external-cavity diode laser and a fiber-based optical frequency comb. The relative uncertainties of the measured absolute frequencies are typically $1.4\\times10^{-11}$. Accurate hyperfine constants of four rovibrational transitions are obtained by fitting the measured hyperfine splittings to a four-term effective Hamiltonian including the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions. The observed transitions can be good frequency references at 578 nm, and are especially useful for research using atomic ytterbium since the transitions are close to the $^{1}S_{0}-^{3}P_{0}$ clock transition of ytterbium.

  10. Theoretical Study of the Energy Spectrum of the 2p3 3p in S IX and Related Electron Transitions

    NASA Astrophysics Data System (ADS)

    Boganovich, P.; Karpuškienė, R.; Udris, A.

    The energy spectrum of S IX was calculated by the configuration interaction method. Calculated wavelengths and oscillator strengths of the electric dipole transitions 2s22p33p-2s22p33d, 2s22p33s-2s22p33p and the two-electron transitions 2s2p5-2s22p33p are presented. The results obtained were compared with the available experimental data.

  11. Systematic Study of the ^87Sr Clock Transition in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Boyd, Martin; Ludlow, Andrew; Zelevinsky, Tanya; Foreman, Seth; Blatt, Sebastian; Notcutt, Mark; Ido, Tetsuya; Ye, Jun

    2006-05-01

    The ^1S0-^3P0 transition in ^87Sr is studied for the realization of an optical atomic clock, using μK atoms in a magic wavelength optical lattice [1]. The probe laser frequency is measured with an octave-spanning fs comb, which is referenced to a hydrogen maser (directly calibrated by the NIST primary Cs fountain clock) allowing high precision evaluation of potential systematic frequency shifts . By varying the lattice wavelength and trapping depth we find that the magic wavelength for the clock transition is 813.418(10) with a clock sensitivity to lattice deviations of ˜2 mHz/MHz for lattice intensities of 10 kW/cm^2. To explore the effect of atomic collisions on the clock frequency we varied the atomic density by a factor of 50 and did not find any shifts at the 3 x10-14 level. Dependence of the clock transition on magnetic fields has been examined as the hyperfine interaction (I = 9/2), which provides the small transition moment for the doubly forbidden clock transition, also results in a differential g factor of the ^3P0 and ^1S0 levels. We will report the latest results of this optical clock system. [1] A.D. Ludlow et al., Phys Rev Lett 96, 033003 (2006).

  12. Transition probability of the Al II 2669 intersystem line

    NASA Technical Reports Server (NTRS)

    Johnson, B. C.; Smith, P. L.; Parkinson, W. H.

    1986-01-01

    Time-resolved observations of the spin-changing, or 'intersystem' emission at 2669.157 A obtained by the ion storage technique are used to measure the transition probability of the 3s2 1S0 - 3s3p 3P1 exp 0 line in Al II. A laser-generated plasma was used as the source of the metastable Al(+) ions. The A-value result obtained for the intersystem transition is 3.33 + or - 0.23 x 10 to the 3rd/sec at the 90-percent confidence level; this value is used to derive two line-intensity ratios which involve the intersystem line as a function of electron density and temperature.

  13. The absolute frequency of the 87Sr optical clock transition

    NASA Astrophysics Data System (ADS)

    Campbell, Gretchen K.; Ludlow, Andrew D.; Blatt, Sebastian; Thomsen, Jan W.; Martin, Michael J.; de Miranda, Marcio H. G.; Zelevinsky, Tanya; Boyd, Martin M.; Ye, Jun; Diddams, Scott A.; Heavner, Thomas P.; Parker, Thomas E.; Jefferts, Steven R.

    2008-10-01

    The absolute frequency of the 1S0-3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6 × 10-16 represents one of the most accurate measurements of an atomic transition frequency to date. After a detailed study of systematic effects, which reduced the total systematic uncertainty of the Sr lattice clock to 1.5 × 10-16, the clock frequency is measured against a hydrogen maser which is simultaneously calibrated to the US primary frequency standard, the NIST Cs fountain clock, NIST-F1. The comparison is made possible using a femtosecond laser based optical frequency comb to phase coherently connect the optical and microwave spectral regions and by a 3.5 km fibre transfer scheme to compare the remotely located clock signals.

  14. Evidence for the non-statistical population of the 1s2s2p4P metastable state by electron capture in 4 MeV collisions of B3+(1s2s 3S) with H2 targets

    NASA Astrophysics Data System (ADS)

    Benis, E. P.; Doukas, S.; Zouros, T. J. M.

    2016-02-01

    We have revisited previously published data involving collisions of mixed 4 MeV B3+ (1s21 S, 1 s 2 s3 S) with H2 targets (Benis et al., 2002) in search of evidence for the non-statistical production of the 1 s 2 s 2 p4 P long-lived metastable state by single electron capture. Using our recently published method for the accurate determination of the effective solid angle of Auger decaying metastable projectile states in combination with knowledge of the 1 s 2 s3 S metastable beam fraction allowed us to determine the ratio R =4 P /2 P of 1 s 2 s 2 p quartet to doublet production cross sections both formed by electron capture. Our present determination of R = 2.8 ± 0.5 , clearly departs from the expected value of R = 2 based on statistical spin recoupling arguments and thus provides evidence for the active presence of additional population mechanisms in a new collision system.

  15. Calculations with Spectroscopic Accuracy: Energies and Transition Rates in the Nitrogen Isoelectronic Sequence from Ar XII to Zn XXIV

    NASA Astrophysics Data System (ADS)

    Wang, K.; Si, R.; Dang, W.; Jönsson, P.; Guo, X. L.; Li, S.; Chen, Z. B.; Zhang, H.; Long, F. Y.; Liu, H. T.; Li, D. F.; Hutton, R.; Chen, C. Y.; Yan, J.

    2016-03-01

    Combined relativistic configuration interaction and many-body perturbation calculations are performed for the 359 fine-structure levels of the 2s2 2p3, 2 s2p4, 2p5, 2s2 2p2 3l, 2 s2p3 3l, 2p4 3l, and 2s2 2p2 4l configurations in N-like ions from Ar xii to Zn xxiv. Complete and consistent data sets of energies, wavelengths, radiative rates, oscillator strengths, and line strengths for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 359 levels are given for each ion. The present work significantly increases the amount of accurate data for ions in the nitrogen-like sequence, and the accuracy of the energy levels is high enough to enable the identification and interpretation of observed spectra involving the n = 3, 4 levels, for which experimental values are largely scarce. Meanwhile, the results should be of great help for modeling and diagnosing astrophysical and fusion plasmas.

  16. Forbidden transition probabilities for ground terms of ions with p or p5 configurations. [for solar atmosphere

    NASA Technical Reports Server (NTRS)

    Kastner, S. O.

    1976-01-01

    Forbidden transition probabilities are given for ground term transitions of ions in the isoelectronic sequences with outer configurations 2s2 2p (B I), 2p5 (F I), 3s2 3p (Al I), and 3p5 (Cl I). Tables give, for each ion, the ground term interval, the associated wavelength, the quadrupole radial integral, the electric quadrupole transition probability, and the magnetic dipole transition probability. Coronal lines due to some of these ions have been observed, while others are yet to be observed. The tales for the Al I and Cl I sequences include elements up to germanium.

  17. Photoabsorption of the ground state of Ne and of Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions

    NASA Astrophysics Data System (ADS)

    Sakho, I.

    2016-03-01

    Photoabsorption of the 1s2 2s2 2p6 (1S0) ground state of Ne-like ions is presented in this paper. Resonance energies and width of the 2 s 2p6 n p1P1 series of Ne and Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions are reported. Wavelengths of the 2s2 2p6 (1S0) → 2s2 2p5(2P 3 / 2 , 1 / 2) n d transitions in neon-like Na+ ion and of the 2s2 2p6(1S0) → 2 s 2p6 n p1P1 transitions in Ne and in Ne-like Na+, Mg2+, Al3+, Si4+, P5+, S6+, and Cl7+ ions are tabulated. Analysis of the resonances investigated is done in the framework of the LS, jj and JK coupling schemes. All the calculations are made using the Screening constant by unit nuclear charge (SCUNC) formalism. Very good agreement is found between the SCUNC results and various experimental and theoretical literature values and new data for the Ne-like Si4+, P5+, S6+, and Cl7+ ions are listed.

  18. Spectroscopy of the 199Hg Optical Clock Transition at 265.5 nm

    NASA Astrophysics Data System (ADS)

    Lytle, Christian; Paul, Justin; Jones, R.

    2013-05-01

    Neutral Hg is an excellent candidate for a stable and accurate atomic clock. The doubly-forbidden clock transition at 265.5 nm can provide an extremely high-quality resonance factor (Q) when confined in an optical lattice at the Stark-shift free ``magic'' wavelength. A key feature of the Hg system is the expected reduced uncertainty of black-body radiation induced Stark shifts compared to other optically-based neutral atom clocks. We demonstrate precision spectroscopy of the 1S0 - 3P0 clock transition in 199Hg in a MOT. The MOT population of 106 atoms was depleted by over 70% using 3 mW from a cavity-stabilized probe laser tuned to the clock transition. We present our characterization of the transition and efforts to implement a stable Hg clock system.

  19. Metric transition

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This report describes NASA's metric transition in terms of seven major program elements. Six are technical areas involving research, technology development, and operations; they are managed by specific Program Offices at NASA Headquarters. The final program element, Institutional Management, covers both NASA-wide functional management under control of NASA Headquarters and metric capability development at the individual NASA Field Installations. This area addresses issues common to all NASA program elements, including: Federal, state, and local coordination; standards; private industry initiatives; public-awareness initiatives; and employee training. The concluding section identifies current barriers and impediments to metric transition; NASA has no specific recommendations for consideration by the Congress.

  20. 750 mW continuous-wave solid-state deep ultraviolet laser source at the 253.7 nm transition in mercury.

    PubMed

    Scheid, Martin; Markert, Frank; Walz, Jochen; Wang, Jiayu; Kirchner, Martin; Hänsch, Theodor W

    2007-04-15

    A high-power continuous-wave coherent light source at 253.7 nm is described. It is based on a solid-state Yb:YAG disk laser with two successive frequency doubling stages and is capable of generating stable output powers of up to 750 mW. Spectroscopy of the 6 (1)S(0)-6 (3)P(1) transition of mercury has been demonstrated. PMID:17375166

  1. The Formation and Spatiotemporal Progress of the pH Wave Induced by the Temperature Gradient in the Thin-Layer H2O2-Na2S2O3-H2SO4-CuSO4 Dynamical System.

    PubMed

    Jędrusiak, Mikołaj; Orlik, Marek

    2016-03-31

    The H2O2-S2O3(2-)-H(+)-Cu(2+) dynamical system exhibits sustained oscillations under flow conditions but reveals only a single initial peak of the indicator electrode potential and pH variation under batch isothermal conditions. Thus, in the latter case, there is no possibility of the coupling of the oscillations and diffusion which could lead to formation of sustained spatiotemporal patterns in this process. However, in the inhomogeneous temperature field, due to dependence of the local reaction kinetics on temperature, spatial inhomogeneities of pH distribution can develop which, in the presence of an appropriate indicator, thymol blue, manifest themselves as the color front traveling along the quasi-one-dimensional reactor. In this work, we describe the experimental conditions under which the above-mentioned phenomena can be observed and present their numerical model based on thermokinetic coupling and spatial coordinate introduced to earlier isothermal homogeneous kinetic mechanism. PMID:26938427

  2. [Humanitarian transition].

    PubMed

    Mattei, Jean-François; Troit, Virginie

    2016-02-01

    In two centuries, modern humanitarian action has experienced several fractures often linked to crises. Although its professionalism and intervention force remain indisputable, it faces, since the 2000s, a new context that limits its ability to act and confronts it with new dilemmas, even though it must deal with needs for aid of unprecedented scale. These difficulties reveal a humanitarian transition period that was not anticipated. This transition period reflects the change from a dominant paradigm of North-South solidarity of Western origin to a much more complex model. This article provides a summary of the current mutations that are dominated by the States' assertion of sovereignty. Among the possible solutions, it argues for an ethical approach and a better integration of the research carried out in the Global South, prerequisites for building a true partnership and placing the victims at the heart of the operations which involve them. PMID:26936180

  3. Eliminating Transitions

    ERIC Educational Resources Information Center

    Gallick, Barb; Lee, Lisa

    2010-01-01

    Adults often find themselves transitioning from one activity to another in a short time span. Most of the time, they do not feel they have a lot of control over their schedules, but wish that they could carve out extended time to relax and focus on one project. Picture a group of children in the block area who have spent 15 or 20 minutes building…

  4. Dynamo Transition

    SciTech Connect

    Verma, M. K.; Yadav, R.; Chandra, M.; Paul, S.; Wahi, P.

    2010-11-23

    In this article we review the experimental and numerical results related to the dynamo transitions. Recent experiments of Von Karman Sodium (VKS) exhibit various dynamo states including constant, time-periodic, and chaotic magnetic fields. Similarly pseudospectral simulations of dynamo show constant, time-periodic, quasiperiodic, and chaotic magnetic field configurations. One of the windows for the magnetic Prandtl number of unity shows period doubling route to chaos. Quasiperiodic route to chaos has been reported for the Prandtl number of 0.5. The dynamo simulations also reveal coexisting multiple attractors that were obtained for different initial conditions.

  5. N = 3 - 3 Transitions of Ne-like Ions in the Iron Group, Especially Ca(10+) and Ti(12+)

    SciTech Connect

    Ishikawa, Y; Encarnacion, J L; Trabert, E

    2008-10-09

    The Ti XIII 2s{sup 2}2p{sup 5}3l-3l{prime} and 2s2p{sup 6}3l-3l{prime} transitions that have been discussed previously on the basis of beam-foil spectra and laser-produced plasmas in comparison to semi-empirically scaled computations have now been treated by accurate ab initio Multi-reference Moller-Plesset calculations. While most 2s{sup 2}2p{sup 5}3l-3l{prime} line identifications are supported by the new calculations, the 2s2p{sup 6}3l-3l{prime} transition arrays are revised. Theoretical level positions are given for all elements from Ca through Fe. The quality of the calculation is demonstrated on the beam-foil spectra of Ca.

  6. Transitions of Zn XXII, Zn XXIII, Zn XXIV, Ge XXIV, and Ge XXV observed in laser-produced plasmas

    NASA Technical Reports Server (NTRS)

    Behring, W. E.; Cohen, L.; Doschek, G. A.; Feldman, U.

    1976-01-01

    Wavelengths and wave numbers are presented for zinc lines in the F I, O I, and N I isoelectronic sequences as well as for germanium lines in the F I and O I sequences. The transitions are of the type 2s(2)2p(k)-2s2p(k+1), and the lines were observed near 100 A in the spectra of plasmas produced by focusing the pulse from a high-power glass laser on to solid targets of different elements and compounds. The results are compared with prediction based on extrapolations of semiempirical formulas derived by Edlen (1969). The wavelengths and wave numbers of some of the corresponding transitions in Cu XXI, Cu XXII, Cu XXIII, Ga XXIII, and Ga XXIV are interpolated with a probable wavelength accuracy of at least plus or minus 0.02 A.

  7. Supramolecular self-organisation and conformational isomerism of a binuclear O,O'-dipropyl dithiophosphate gold(I) complex, [Au2{S2P(OC3H7)2}2]: Synthesis, (13)C and (31)P CP/MAS NMR spectroscopy, single-crystal X-ray diffraction study and thermal behaviour.

    PubMed

    Rodina, Tatyana A; Korneeva, Eugenia V; Antzutkin, Oleg N; Ivanov, Alexander V

    2015-10-01

    Crystalline one-dimensional polymeric catena-poly[bis(μ2-O,O'-dipropyldithiophosphato-S,S')digold(I)] (Au-Au) (1) was prepared and studied using (13)C and (31)P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. To elucidate the structural function of Dtph ligands in crystalline gold(I) O,O'-dipropyl dithiophosphate, the chemical shift anisotropy parameters (δaniso and η) were calculated from spinning sideband manifolds in (31)P MAS NMR spectra. A novel structure of the gold(I) compound comprises two isomeric, non-centrosymmetric binuclear molecules of [Au2{S2P(OC3H7)2}2] (isomers 'A' and 'B'), whose four Dtph groups display structural inequivalence. In each isomeric binuclear molecule of 1, a pair of μ2-bridging dipropyl Dtph ligands almost symmetrically links two neighbouring gold atoms, forming an extensive eight-membered metallocycle [Au2S4P2], while the intramolecular aurophilic Au⋯Au bond additionally stabilises this central cyclic moiety. At the supramolecular level of complex 1, intermolecular aurophilic Au⋯Au bonds yield almost linear infinite polymeric chains (⋯'A'⋯'B'⋯'A'⋯'B'⋯)n. The thermal behaviour of this compound was studied by the simultaneous thermal analysis (STA) technique (a combination of TG and DSC) under an argon atmosphere. PMID:26004097

  8. Temperature Measurements in the Solar Transition Region Using N III Line Intensity Ratios

    NASA Technical Reports Server (NTRS)

    Doron, R.; Doschek, G. A.; Laming, J. M.; Feldman, U.; Bhatia, A. K.

    2003-01-01

    UV emission from B-like N and O ions a rather rare opportunity for recording spectral lines in a narrow wavelength range that can potentially be used to derive temperatures relevant to the solar transition region. In these ions, the line intensity ratios of the type (2s2p(sup 2) - 2p(sup 3)) / (2s(sup 2)2p - 2s2p(sup 2)) are very sensitive to the electron temperature. Additionally, the lines involving the ratios fall within a range of only - 12 A; in N III the lines fall in the 980 - 992 A range and in O IV in the 780 - 791 A range. In this work, we explore the use of these atomic systems, primarily in N III, for temperature diagnostics of the transition region by analyzing UV spectra obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer flown on the Solar and Heliospheric Observatory (SOHO). The N III temperature-sensitive line ratios are measured in more than 60 observations. Most of the measured ratios correspond to temperatures in the range 5.7x10(exp 4) - 6.7x10(exp 4) K. This range is considerably lower than the calculated temperature of maximum abundance of N III, which is approx. 7.6x10(exp 4) K. Detailed analysis of the spectra further indicates that the measured ratios are probably somewhat overestimated due to resonant scattering effects in the 2s(sup 2)2p - 2s2p(sup 2) lines and small blends in the 2s2p(sup 2) - 2p3 lines. Actual lower ratios would only increase the disagreement between the ionization balance calculations and present temperature measurements based on a collisional excitation model. In the case of the O IV spectra, we determined that due to the close proximity in wavelength of the weak line (2s2p(sup 2)-2p3 transitions) to a strong Ne VIII line, sufficiently accurate ratio measurements cannot be obtained. Subject headings: atomic data --- atomic processes --- Sun: transition region --- Sun: U V radiation --- techniques: spectroscopic

  9. Studies to investigate the in vivo therapeutic window of the gamma-secretase inhibitor N2-[(2S)-2-(3,5-difluorophenyl)-2-hydroxyethanoyl]-N1-[(7S)-5-methyl-6-oxo-6,7-dihydro-5H-dibenzo[b,d]azepin-7-yl]-L-alaninamide (LY411,575) in the CRND8 mouse.

    PubMed

    Hyde, Lynn A; McHugh, Nansie A; Chen, Joseph; Zhang, Qi; Manfra, Denise; Nomeir, Amin A; Josien, Hubert; Bara, Thomas; Clader, John W; Zhang, Lili; Parker, Eric M; Higgins, Guy A

    2006-12-01

    Accumulation of amyloid beta-peptide (Abeta) is considered a key step in the etiology of Alzheimer's disease. Abeta is produced by sequential cleavage of the amyloid precursor protein by beta- and gamma-secretase enzymes. Consequently, inhibition of gamma-secretase provides a promising therapeutic approach to treat Alzheimer's disease. Preclinically, several gamma-secretase inhibitors have been shown to reduce plasma and brain Abeta, although they also produce mechanism-based side effects, including thymus atrophy and intestinal goblet cell hyperplasia. The present studies sought to establish an efficient screen for determining the therapeutic window of gamma-secretase inhibitors and to test various means of maximizing this window. Six-day oral administration of the gamma-secretase inhibitor N(2)-[(2S)-2-(3,5-difluorophenyl)-2-hydroxyethanoyl]-N(1)-[(7S)-5-methyl-6-oxo-6,7-dihydro-5H-dibenzo[b,d]azepin-7-yl]-l-alaninamide (LY411,575) reduced cortical Abeta(40) in young (preplaque) transgenic CRND8 mice (ED(50) approximately 0.6 mg/kg) and produced significant thymus atrophy and intestinal goblet cell hyperplasia at higher doses (>3 mg/kg). The therapeutic window was similar after oral and subcutaneous administration and in young and aged CRND8 mice. Both the thymus and intestinal side effects were reversible after a 2-week washout period. Three-week treatment with 1 mg/kg LY411,575 reduced cortical Abeta(40) by 69% without inducing intestinal effects, although a previously unreported change in coat color was observed. These studies demonstrate that the 3- to 5-fold therapeutic window for LY411,575 can be exploited to obtain reduction in Abeta levels without induction of intestinal side effects, that intermittent treatment could be used to mitigate side effects, and that a 6-day dosing paradigm can be used to rapidly determine the therapeutic window of novel gamma-secretase inhibitors. PMID:16946102

  10. Transitions: A Personal Perspective.

    ERIC Educational Resources Information Center

    Wood, Ann Stace

    1995-01-01

    Distinguishes between unchosen transitions (children maturing and leaving, parents aging, companies downsizing) and chosen ones (moving, divorce, marriage, career changes). Describes the steps one goes through: uneasiness, renewed energy, complaining, exploration, partial transition, and the completed transition. (JOW)

  11. Doppler spectroscopy of an ytterbium Bose-Einstein condensate on the clock transition

    NASA Astrophysics Data System (ADS)

    Dareau, A.; Scholl, M.; Beaufils, Q.; Döring, D.; Beugnon, J.; Gerbier, F.

    2015-02-01

    We describe Doppler spectroscopy of Bose-Einstein condensates of ytterbium atoms using a narrow optical transition. We address the optical clock transition around 578 nm between the 1S0 and the 3P0 states with a laser system locked on a high-finesse cavity. We show how the absolute frequency of the cavity modes can be determined within a few tens of kilohertz using high-resolution spectroscopy on molecular iodine. We show that optical spectra reflect the velocity distribution of expanding condensates in free fall or after release inside an optical waveguide. We demonstrate subkilohertz spectral linewidths, with long-term drifts of the resonance frequency well below 1 kHz/h. These results open the way to high-resolution spectroscopy of many-body systems.

  12. Characterization of [3H]-(2S,2′R,3′R)-2-(2′,3′-dicarboxy- cyclopropyl)glycine ([3H]-DCG IV) binding to metabotropic mGlu2 receptor-transfected cell membranes

    PubMed Central

    Cartmell, Jayne; Adam, Geo; Chaboz, Sylvie; Henningsen, Robert; Kemp, John A; Klingelschmidt, Agnes; Metzler, Veit; Monsma, Frederick; Schaffhauser, Hervé; Wichmann, Jürgen; Mutel, Vincent

    1998-01-01

    The binding of the new selective group II metabotropic glutamate receptor radioligand, [3H]-(2S,2′R,3′R)-2-(2′,3′-dicarboxycyclopropyl)glycine ([3H]-DCG IV), was characterized in rat mGlu2 receptor-transfected CHO cell membranes. [3H]-DCG IV binding was pH-dependent, but was not sensitive to temperature. Saturation analysis showed the presence of a single binding site, with a Kd value of 160 nM and a Bmax value of 10 pmol mg−1 protein. Binding was not sensitive to Na+-dependent glutamate uptake blockers or Cl−-dependent glutamate binding inhibitors. Furthermore, up to concentrations of 1 mM, the glutamate ionotropic receptor agonists, N-methyl-D-aspartic acid (NMDA), (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate, did not affect [3H]-DCG IV binding. Of the compounds observed to inhibit [3H]-DCG IV binding, the most potent were the recently described selective group II agonist, (+)-2-aminobicyclo-[3.1.0]hexane-2,6-dicarboxylate (LY 354740; Ki value 16 nM) and antagonist, 2-amino-2-(2-carboxycyclopropan-1-yl)-3-(dibenzopyran-4-yl) propanoic acid (LY 341495; Ki value 19 nM). As expected, for a G-protein-coupled receptor, guanosine-5′-O-(3-thiotriphosphate) (GTPγS) inhibited [3H]-DCG IV binding in a concentration-dependent manner, with an IC50 value of 12 nM. A highly significant correlation was observed between the potencies of compounds able to inhibit [3H]-DCG IV binding and potencies obtained for agonist activity in a GTPγ35S binding functional assay. In addition, these studies identified a number of compounds with previously unknown activity at mGlu2 receptors, including L(+)-2-amino-3-phosphonopropionic acid (L-AP3), L(+)-2-amino-5-phosphonopentanoic acid (L-AP5), 3-((RS)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (R-CPP), N-acetyl-L-aspartyl-L-glutamic acid (NAAG) and (RS)-α-methylserine-O-phosphate (MSOP). PMID:9504391

  13. Effects of a Fusarium toxin-contaminated triticale, either untreated or treated with sodium metabisulphite (Na2S2O5, SBS), on weaned piglets with a special focus on liver function as determined by the 13C-methacetin breath test.

    PubMed

    Dänicke, Sven; Beineke, Andreas; Goyarts, Tanja; Valenta, Hana; Beyer, Marita; Humpf, Hans-Ulrich

    2008-08-01

    The aim of the present experiment was to test the effects of a wet preservation of triticale contaminated mainly with deoxynivalenol (DON) with sodium metabisulphite (Na2S2O5, SBS) on growth performance, liver function, clinical-chemical plasma parameters and organ histopathology of piglets. For this purpose both the uncontaminated control triticale and the DON contaminated triticale were included in the piglet diet either untreated (CON, FUS) or SBS-treated (CON-SBS, FUS-SBS) and fed for 28 d starting from weaning. The dietary concentrations of DON and DON sulfonate (DONS), the DON derivative resulting from the SBS treatment, amounted to 0.156, 0.084, 2.312 and 0.275 mg DON per kg CON, CON-SBS, FUS and FUS-SBS diet, and to <0.05, <0.05, <0.05 and 1.841 mg/kg diet, respectively. Feeding the FUS diet significantly reduced the feed intake compared to the other three groups as indicated by the significant interactions between triticale source and SBS treatment when the whole experimental period of 28 d was considered (p = 0.014) while live weight gain and feed to gain ratio remained unaffected. The total plasma protein concentration was significantly depressed due to feeding the contaminated diets whereas SBS treatment exerted an increasing effect at the same time (45.4, 49.5, 40.7 and 46.5 g/l for piglets fed the CON, CON-SBS, FUS and FUS-SBS diet, respectively). The liver function was tested by the 13C-methacetin breath test (MBT) allowing evaluation of the cytochrome P4501A2 activity. MBT results, expressed as cumulative percentage dose recovery after 360 min (cPDR360) revealed a slight stimulation of liver function due to SBS treatment (p = 0.052) (37.5, 39.4, 37.4 and 55.1% for piglets fed the CON, CON-SBS, FUS and FUS-SBS diet, respectively). Liver weight and histopathological scoring were only weakly related to the MBT results. Further histopathological examinations of kidneys, pancreas and heart revealed no treatment effects. It was concluded that the SBS

  14. PyTransit: Transit light curve modeling

    NASA Astrophysics Data System (ADS)

    Parviainen, Hannu

    2015-05-01

    PyTransit implements optimized versions of the Giménez and Mandel & Agol transit models for exoplanet transit light-curves. The two models are implemented natively in Fortran with OpenMP parallelization, and are accessed by an object-oriented python interface. PyTransit facilitates the analysis of photometric time series of exoplanet transits consisting of hundreds of thousands of data points, and of multipassband transit light curves from spectrophotometric observations. It offers efficient model evaluation for multicolour observations and transmission spectroscopy, built-in supersampling to account for extended exposure times, and routines to calculate the projected planet-to-star distance for circular and eccentric orbits, transit durations, and more.

  15. Precise Measurement of Vibrational Transition Frequency of Optically Trapped Molecules

    NASA Astrophysics Data System (ADS)

    Kajita, Masatoshi; Gopakumar, Geetha; Abe, Minori; Hada, Masahiko

    2013-06-01

    We propose to measure the X^{2}Σ(v,N,F,M) =( 0,0,3/2,±3/2) →( v_{u},0,3/2,±3/2) ( v_{u}=1,2,3,4,,,,) transition frequencies of X^{6}Li molecules with the uncertainty lower than 10^{-16} (X: ^{174}Yb, ^{88}Sr, ^{40}Ca). Molecules are produced by photo-association of cold atoms and trapped in the optical lattices. Measurement with molecules in optical lattices is particularly advantageous for precision measurements because (1) the molecules and probe laser interact for a long time, (2) molecules are localized within the Lamb-Dicke region, (3) the measurement is possible with a large number of molecules, and (4) collision effects are suppressed (molecules are trapped at different positions in 2D lattices). Using the proper trap laser frequency, the Stark shift induced by the trap laser is eliminated as the Stark energy shift of the upper and lower states are equal (magic frequency). When the trap laser frequency is shifted from the magic frequency by 1 MHz, the Stark shift is less than 3×10^{-15}. The N=0→0 transition is one-photon forbidden, and it is stimulated by Raman transition using two lasers. When one of two Raman lasers is higher than the magic frequency and another is lower, the total Stark shift induced by two Raman lasers can be eliminated. Measurement of molecular vibrational transition frequencies is useful to test the variation in the proton-to-electron mass ratio. The ^{1}S_{0}-^{3}% P_{0} transition frequencies of ^{27}Al^{+} ion or ^{87}Sr atom are useful as the reference.

  16. Oscillator strengths for transitions in C-like ions between K XIV and Mn XX

    NASA Astrophysics Data System (ADS)

    Aggarwal, K. M.; Keenan, F. P.; Msezane, A. Z.

    2003-04-01

    Energy levels and oscillator strengths (transition probabilities) have been calculated for transitions among 46 fine-structure levels of the (1s2) 2s22p2, 2s2p3, 2p4, 2s22p3s, 2s22p3p and 2s22p3d configurations of C-like K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX using the GRASP code. Configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels agree within 3% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions. Tables \\ref{tab4} to \\ref{tab9} are only available in electronic form at http://www.edpsciences.org

  17. Gas turbine combustor transition

    DOEpatents

    Coslow, Billy Joe; Whidden, Graydon Lane

    1999-01-01

    A method of converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit.

  18. Gas turbine combustor transition

    DOEpatents

    Coslow, B.J.; Whidden, G.L.

    1999-05-25

    A method is described for converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit. 7 figs.

  19. Conceptualizing Transitions to Adulthood

    ERIC Educational Resources Information Center

    Wyn, Johanna

    2014-01-01

    This chapter provides an overview of theories of the transition to young adulthood. It sets out the argument for conceptual renewal and discusses some implications of new patterns of transition for adult education.

  20. The Managerial Transition.

    ERIC Educational Resources Information Center

    Kneeland, Steven J.

    1980-01-01

    Having identified the problem of managerial transition in a previous article (CE 510 277), the author outlines a strategy for change which includes performance appraisal, definition of the management structure, and counselling for the individual in transition. (SK)

  1. Glass transition(s) of ionomers

    SciTech Connect

    Weiss, R.A.

    1994-09-01

    Ionomers are predominantly nonpolar polymers that contain a small amount of bonded salt groups. Microphase separation of ion-rich microdomains occurs as a consequence of the thermodynamic incompatibility of the salt groups and the polymer matrix and associative interactions between salt groups. Associations of the salt groups usually increase the glass transition of the continuous matrix phase, presumably as a consequence of the inhibition of chain mobility that accompanies physical crosslinking. The central question raised in this paper is whether the dispersed ion-rich microphase exhibits a glass transition. Although no glass transition for the microphase is detected by calorimetry, a dynamic mechanical relaxation is commonly observed above the T{sub g} of the matrix phase. This transition has some of the attributes of a glass transition, but it is not clear what is the actual relaxation process that is measured. This paper discusses the effect of the ionic groups on the matrix glass transition, the origin of the high-temperature dynamic mechanical transition, and the effects of the addition of plasticizers on the T{sub g} of the matrix and the higher temperature mechanical relaxation.

  2. Transition in Turbines

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The concept of a large disturbance bypass mechanism for the initiation of transition is reviewed and studied. This mechanism, or some manifestation thereof, is suspected to be at work in the boundary layers present in a turbine flow passage. Discussion is presented on four relevant subtopics: (1) the effect of upstream disturbances and wakes on transition; (2) transition prediction models, code development, and verification; (3) transition and turbulence measurement techniques; and (4) the hydrodynamic condition of low Reynolds number boundary layers.

  3. Transitivity of Preferences

    ERIC Educational Resources Information Center

    Regenwetter, Michel; Dana, Jason; Davis-Stober, Clintin P.

    2011-01-01

    Transitivity of preferences is a fundamental principle shared by most major contemporary rational, prescriptive, and descriptive models of decision making. To have transitive preferences, a person, group, or society that prefers choice option "x" to "y" and "y" to "z" must prefer "x" to "z". Any claim of empirical violations of transitivity by…

  4. Transition: Terms and Concepts.

    ERIC Educational Resources Information Center

    O'Leary, Ed

    This paper provides explanations and case examples of some terms and concepts related to transition of students with disabilities under 1997 amendments to the Individuals with Disabilities Education Act. Explanations and examples focus on the concepts of "statement of transition service needs" and "statement of needed transition services". The…

  5. Effective collision strengths for fine-structure transitions in Si VII

    SciTech Connect

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

    2014-05-20

    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 {sup 2}2p {sup 4}, 2s2p {sup 5}, 2p {sup 6}, 2s {sup 2}2p {sup 3}3s, 2s {sup 2}2p {sup 3}3p, 2s {sup 2}2p {sup 3}3d, and 2s2p {sup 4}3s 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 and Zeippen and the 44 LS-state distorted wave calculation of Bhatia and Landi.

  6. High-resolution photoassociation spectroscopy of ultracold ytterbium atoms by using the intercombination transition.

    PubMed

    Tojo, Satoshi; Kitagawa, Masaaki; Enomoto, Katsunari; Kato, Yutaka; Takasu, Yosuke; Kumakura, Mitsutaka; Takahashi, Yoshiro

    2006-04-21

    We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden 1S0 - 3P1 intercombination line. The rovibrational levels in the 0u+ state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of 174Yb and those of 176Yb, a d-wave shape resonance for 174Yb is strongly suggested. PMID:16712155

  7. Gravitationally induced quantum transitions

    NASA Astrophysics Data System (ADS)

    Landry, A.; Paranjape, M. B.

    2016-06-01

    In this paper, we calculate the probability for resonantly inducing transitions in quantum states due to time-dependent gravitational perturbations. Contrary to common wisdom, the probability of inducing transitions is not infinitesimally small. We consider a system of ultracold neutrons, which are organized according to the energy levels of the Schrödinger equation in the presence of the Earth's gravitational field. Transitions between energy levels are induced by an oscillating driving force of frequency ω . The driving force is created by oscillating a macroscopic mass in the neighborhood of the system of neutrons. The neutron lifetime is approximately 880 sec while the probability of transitions increases as t2. Hence, the optimal strategy is to drive the system for two lifetimes. The transition amplitude then is of the order of 1.06 ×10-5, and hence with a million ultracold neutrons, one should be able to observe transitions.

  8. Moons over Jupiter: transits and shadow transits

    NASA Astrophysics Data System (ADS)

    Rogers, J. H.; et al.

    2003-06-01

    There is no more beautiful illustration of orbital motions than the movements of Jupiter's satellites. Every six years, their movements are most strikingly displayed, when the jovian system is presented edge-on to Earth. This means that there is a higher frequency of multiple transits over the face of the planet, as all the moons transit across the equatorial zone, whereas in other years Ganymede and Callisto transit near the poles or not at all. Also, for a few months, the satellites pass in front of each other, displaying mutual eclipses and occultations. In 2002/2003 we have been able to observe a fine series of these multiple and mutual events. On the cover, and on these pages, are some of the highest-resolution images received.

  9. Dynamical Transition in polypeptides

    NASA Astrophysics Data System (ADS)

    He, Yunfen; Markelz, Andrea

    2008-03-01

    Two of the possible causes for the so called dynamical transition (the rapid increase in flexibility for biomolecules at ˜ 200 K) are: thermally activated side chain diffusive motions with hydration dependent activation energies; or a glass transition in the biological water directly adjacent to the biomolecule. If the transition is strictly due to side chain activation, it should not depend on protein structure. Previously we demonstrated that the dynamical transition remains after tertiary structure was removed using THz time domain dielectric spectroscopy (0.2 -2.0 THz, 0.5-5ps). Here measurements on polyalanine as a function of chain length show that the dynamical transition does not occur for peptide length shorter than 5. However, the transition is observed for 5 mer and higher. Structural and simulation studies indicate that the 5 mer transiently occupies structured forms [1,2]. These results suggest that A) the dynamical transition is not due to thermally activated side chain motion and B) secondary structure is necessary for the dynamical transition. Secondary structure possibly induces sufficient ordering in the adjacent water to result in a fragile to strong glass transition resulting in increased protein flexibility [3]. [1] KAH Wildman et al. Solid State Nucl. Magn. Reson. 24 (2003) 94-109. [2] Yuguang Mu,et al. Proteins 58, (2005) 45-52. [3] S.H. Chen et al. PNAS (2006) 9012--9016.

  10. Photoinduced phase transitions.

    PubMed

    Bennemann, K H

    2011-02-23

    Optically induced ultrafast electronic excitations with sufficiently long lifetimes may cause strong effects on phase transitions like structural and nonmetal→metal ones and on supercooling, supersaturation, etc. Examples are the transitions diamond→graphite, graphite→graphene, non-metal→metal, solid→liquid and vapor→liquid, solid. Photoinduced formation of graphene and water condensation of saturated or supersaturated vapor due to increased bonding amongst water molecules are of particular interest. These nonequilibrium transitions are an ultrafast response, on a few hundred fs time scale, to the fast low to large energy electronic excitations. The energy of the photons is converted into electronic energy via electronic excitations changing the cohesive energy. This changes the chemical potential controlling the phase transition. In view of the advances in laser optics photon induced transitions are expected to become an active area in nonequilibrium physics and phase transition dynamics. Conservation laws like energy or angular momentum conservation control the time during which the transitions occur. Since the photon induced effects result from weakening or strengthening of the bonding between the atoms or molecules transitions like solid/liquid, etc can be shifted in both directions. Photoinduced transitions will be discussed from a unified point of view. PMID:21411879

  11. Transition to Old Age (Transition to Retirement).

    ERIC Educational Resources Information Center

    Bergman, Simon

    Several conceptualizations and definitions of retirement have been proposed. One of them--the three-stage transition process--can be illustrated from studies in Israel: (1) leaving the old role; (2) going through the act of formal separation; and (3) adjusting to the new situation and role. Today's higher rate of survival into later years means…

  12. Electron impact excitation of resonance transitions in atomic potassium

    SciTech Connect

    Tayal, S.S.; Msezane, A.Z.

    1993-05-01

    Cross sections for electron impact excitation of the 4 s{sup 2}S - 4p {sup 2}P{sup o} and 4s {sup 2}S - 5p {sup 2}P{sup o} transitions in atomic potassium are calculated in the low-energy region from 1.5 to 30 eV using the R-matrix method. We included eight target states (4s {sup 2}S, 4p {sup 2}P{sup o}, 5s {sup 2}S, 3d {sup 2}D, 5p {sup 2}P{sup o}, 4d {sup 2}D, 6S {sup 2}S, and 4f {sup 2}F{sup o}) in the close-coupling expansion. These states are represented by extensive configuration- interaction wavefunctions constructed from the orthogonal one-electron orbitals: 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, and 6s. The calculated results are compared with the available experiments and other calculations. The present calculation shows a resonance structure in the cross section for the excitation of the resonance 4s {sup 2}S - 4p {sup 2}P{sup o} transition around 2.5 eV.

  13. Transitions in Spousal Caregiving.

    ERIC Educational Resources Information Center

    Burton, Lynda C.; Zdaniuk, Bozena; Schulz, Richard; Jackson, Sharon; Hirsch, Calvin

    2003-01-01

    Describes transitions over 5 years among community-dwelling elderly spouses into and within caregiving roles and associated health outcomes. The trajectory of health outcomes associated with caregiving was generally downward. Those who transitioned to heavy caregiving had more symptoms of depression, and poorer self-reported health and health…

  14. Good Transitions = Great Starts!

    ERIC Educational Resources Information Center

    Our Children: The National PTA Magazine, 2012

    2012-01-01

    The smooth transition of outgoing and incoming board members and officers is of vital importance and can determine the PTA's success for years to come. The transition process is the responsibility of both incoming and outgoing officers and board members. It gives closure to those leaving their positions and allows those coming in to be properly…

  15. Children and Transition Time.

    ERIC Educational Resources Information Center

    Baker, Betty Ruth

    Daily transitions in early childhood centers and classrooms include periods when children are completing one activity, preparing to begin a new activity, and moving from place to place in a room or building. Transition activities involve teaching techniques that prepare learners to listen, relax, sit down, move between locations or activities, and…

  16. Matter in transition

    NASA Astrophysics Data System (ADS)

    Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington

    2016-04-01

    We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU( N) require Weierstrass models that cannot be realized from the standard SU( N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.

  17. Transitioning between Clerkship Directors

    ERIC Educational Resources Information Center

    Soltys, Stephen M.; Pary, Robert J.; Robinson, Stephen W.; Markwell, Stephen J.

    2011-01-01

    Objective: The authors report on succession-planning for mid-level academic positions. Method: The authors describe the process of succession-planning between clerkship directors and the smooth transition resulting in one case. Results: Gradually transitioning allowed a new faculty person to assume the clerkship-director position with minimal…

  18. Researching Student Transitions

    ERIC Educational Resources Information Center

    Voorhees, Richard A.; Smith, Gregory P.; Luan, Jing

    2006-01-01

    This article sketches a research agenda for the further study of community college student transitions. Specific techniques are depicted as are potential data sources that can be used to pursue that agenda. The role of student tracking systems in transition research is discussed as well as the applicability of national surveys to the study of…

  19. Transitions and Linkages.

    ERIC Educational Resources Information Center

    Ilfeld, Ellen M., Ed.; Hanssen, Elizabeth, Ed.

    1997-01-01

    If children are to benefit from a healthy, supportive early childhood experience, it is important to strengthen transitions between early childhood experiences in educational and care settings and the more formal educational system. This issue of Coordinator's Notebook focuses on strengthening linkages and transitions between home, preschool, and…

  20. A Posteriori Transit Probabilities

    NASA Astrophysics Data System (ADS)

    Stevens, Daniel J.; Gaudi, B. Scott

    2013-08-01

    Given the radial velocity (RV) detection of an unseen companion, it is often of interest to estimate the probability that the companion also transits the primary star. Typically, one assumes a uniform distribution for the cosine of the inclination angle i of the companion's orbit. This yields the familiar estimate for the prior transit probability of ~Rlowast/a, given the primary radius Rlowast and orbital semimajor axis a, and assuming small companions and a circular orbit. However, the posterior transit probability depends not only on the prior probability distribution of i but also on the prior probability distribution of the companion mass Mc, given a measurement of the product of the two (the minimum mass Mc sin i) from an RV signal. In general, the posterior can be larger or smaller than the prior transit probability. We derive analytic expressions for the posterior transit probability assuming a power-law form for the distribution of true masses, dΓ/dMcvpropMcα, for integer values -3 <= α <= 3. We show that for low transit probabilities, these probabilities reduce to a constant multiplicative factor fα of the corresponding prior transit probability, where fα in general depends on α and an assumed upper limit on the true mass. The prior and posterior probabilities are equal for α = -1. The posterior transit probability is ~1.5 times larger than the prior for α = -3 and is ~4/π times larger for α = -2, but is less than the prior for α>=0, and can be arbitrarily small for α > 1. We also calculate the posterior transit probability in different mass regimes for two physically-motivated mass distributions of companions around Sun-like stars. We find that for Jupiter-mass planets, the posterior transit probability is roughly equal to the prior probability, whereas the posterior is likely higher for Super-Earths and Neptunes (10 M⊕ - 30 M⊕) and Super-Jupiters (3 MJup - 10 MJup), owing to the predicted steep rise in the mass function toward smaller

  1. Extrasolar Planetary Transits

    NASA Astrophysics Data System (ADS)

    Cameron, Andrew Collier

    An extrasolar planet will transit the visible hemisphere of its host star if its orbital plane lies sufficiently close to the observer's line of sight. The resulting periodic dips in stellar flux reveal key system parameters, including the density of the host star and, if radial-velocity observations are available, the surface gravitational acceleration of the planet. In this chapter I present the essential methodology for modelling the time-dependent flux variation during a transit, and its use in determining the posterior probability distribution for the physical parameters of the system. Large-scale searches for transiting systems are an efficient way of discovering planets whose bulk densities, and hence compositions, can be accessed if their masses can also be determined. I present algorithms for detrending large ensembles of light curves, for searching for transit-like signals among them. I also discuss methods for identifying diluted stellar eclipsing binaries mimicking planetary transit signals, and validation of transit candidates too faint for radial-velocity follow-up. I review the use of time-resolved spectrophotometry and high-resolution spectroscopy during transits to identify the molecular constituents of exoplanetary atmospheres.

  2. Predictability of critical transitions.

    PubMed

    Zhang, Xiaozhu; Kuehn, Christian; Hallerberg, Sarah

    2015-11-01

    Critical transitions in multistable systems have been discussed as models for a variety of phenomena ranging from the extinctions of species to socioeconomic changes and climate transitions between ice ages and warm ages. From bifurcation theory we can expect certain critical transitions to be preceded by a decreased recovery from external perturbations. The consequences of this critical slowing down have been observed as an increase in variance and autocorrelation prior to the transition. However, especially in the presence of noise, it is not clear whether these changes in observation variables are statistically relevant such that they could be used as indicators for critical transitions. In this contribution we investigate the predictability of critical transitions in conceptual models. We study the quadratic integrate-and-fire model and the van der Pol model under the influence of external noise. We focus especially on the statistical analysis of the success of predictions and the overall predictability of the system. The performance of different indicator variables turns out to be dependent on the specific model under study and the conditions of accessing it. Furthermore, we study the influence of the magnitude of transitions on the predictive performance. PMID:26651760

  3. Predictability of critical transitions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaozhu; Kuehn, Christian; Hallerberg, Sarah

    2015-11-01

    Critical transitions in multistable systems have been discussed as models for a variety of phenomena ranging from the extinctions of species to socioeconomic changes and climate transitions between ice ages and warm ages. From bifurcation theory we can expect certain critical transitions to be preceded by a decreased recovery from external perturbations. The consequences of this critical slowing down have been observed as an increase in variance and autocorrelation prior to the transition. However, especially in the presence of noise, it is not clear whether these changes in observation variables are statistically relevant such that they could be used as indicators for critical transitions. In this contribution we investigate the predictability of critical transitions in conceptual models. We study the quadratic integrate-and-fire model and the van der Pol model under the influence of external noise. We focus especially on the statistical analysis of the success of predictions and the overall predictability of the system. The performance of different indicator variables turns out to be dependent on the specific model under study and the conditions of accessing it. Furthermore, we study the influence of the magnitude of transitions on the predictive performance.

  4. Holographic magnetic phase transition

    SciTech Connect

    Lifschytz, Gilad; Lippert, Matthew

    2009-09-15

    We study four-dimensional interacting fermions in a strong magnetic field, using the holographic Sakai-Sugimoto model of intersecting D4- and D8-branes in the deconfined, chiral-symmetric parallel phase. We find that as the magnetic field is varied, while staying in the parallel phase, the fermions exhibit a first-order phase transition in which their magnetization jumps discontinuously. Properties of this transition are consistent with a picture in which some of the fermions jump to the lowest Landau level. Similarities to known magnetic phase transitions are discussed.

  5. Geomagnetic polarity transitions

    NASA Astrophysics Data System (ADS)

    Merrill, Ronald T.; McFadden, Phillip L.

    1999-05-01

    The top of Earth's liquid outer core is nearly 2900 km beneath Earth's surface, so we will never be able to observe it directly. This hot, dense, molten iron-rich body is continuously in motion and is the source of Earth's magnetic field. One of the most dynamic manifestations at Earth's surface of this fluid body is, perhaps, a reversal of the geomagnetic field. Unfortunately, the most recent polarity transition occurred at about 780 ka, so we have never observed a transition directly. It seems that a polarity transition spans many human lifetimes, so no human will ever witness the phenomenon in its entirety. Thus we are left with the tantalizing prospect that paleomagnetic records of polarity transitions may betray some of the secrets of the deep Earth. Certainly, if there are systematics in the reversal process and they can be documented, then this will reveal substantial information about the nature of the lowermost mantle and of the outer core. Despite their slowness on a human timescale, polarity transitions occur almost instantaneously on a geological timescale. This rapidity, together with limitations in the paleomagnetic recording process, prohibits a comprehensive description of any reversal transition both now and into the foreseeable future, which limits the questions that may at this stage be sensibly asked. The natural model for the geomagnetic field is a set of spherical harmonic components, and we are not able to obtain a reliable model for even the first few harmonic terms during a transition. Nevertheless, it is possible, in principle, to make statements about the harmonic character of a geomagnetic polarity transition without having a rigorous spherical harmonic description of one. For example, harmonic descriptions of recent geomagnetic polarity transitions that are purely zonal can be ruled out (a zonal harmonic does not change along a line of latitude). Gleaning information about transitions has proven to be difficult, but it does seem

  6. Alternative fuel transit buses

    SciTech Connect

    Motta, R.; Norton, P.; Kelly, K.

    1996-10-01

    The National Renewable Energy Laboratory (NREL) is a U.S. Department of Energy (DOE) national laboratory; this project was funded by DOE. One of NREL`s missions is to objectively evaluate the performance, emissions, and operating costs of alternative fuel vehicles so fleet managers can make informed decisions when purchasing them. Alternative fuels have made greater inroads into the transit bus market than into any other. Each year, the American Public Transit Association (APTA) surveys its members on their inventory and buying plans. The latest APTA data show that about 4% of the 50,000 transit buses in its survey run on an alternative fuel. Furthermore, 1 in 5 of the new transit buses that members have on order are alternative fuel buses. This program was designed to comprehensively and objectively evaluate the alternative fuels in use in the industry.

  7. Superconductivity in transition metals.

    PubMed

    Slocombe, Daniel R; Kuznetsov, Vladimir L; Grochala, Wojciech; Williams, Robert J P; Edwards, Peter P

    2015-03-13

    A qualitative account of the occurrence and magnitude of superconductivity in the transition metals is presented, with a primary emphasis on elements of the first row. Correlations of the important parameters of the Bardeen-Cooper-Schrieffer theory of superconductivity are highlighted with respect to the number of d-shell electrons per atom of the transition elements. The relation between the systematics of superconductivity in the transition metals and the periodic table high-lights the importance of short-range or chemical bonding on the remarkable natural phenomenon of superconductivity in the chemical elements. A relationship between superconductivity and lattice instability appears naturally as a balance and competition between localized covalent bonding and so-called broken covalency, which favours d-electron delocalization and superconductivity. In this manner, the systematics of superconductivity and various other physical properties of the transition elements are related and unified. PMID:25666075

  8. The Heliosphere in Transition

    NASA Astrophysics Data System (ADS)

    Kasper, Justin

    2015-04-01

    The heliosphere consists of the connective tissue of particles, fields and photons that mediate our interaction with the Sun and with interstellar space. Exploration of the heliosphere yields clues to the nature of environments we cannot reach ourselves, illuminating the composition of the solar interior, or the acceleration of cosmic rays in the galaxy. The heliosphere is also a laboratory for us to understand the fundamental physics of magnetized plasma, from heating and instabilities to coupling with neutral gas and dust. This talk will review some of the most exciting recent results in the heliosphere with a focus on transitions: what we can learn by exploring transitions within the heliosphere, how the heliosphere is responding to the long term transition in solar activity, and how our very view of the heliosphere is in transition with upcoming missions such as Solar Probe Plus, Solar Orbiter and IMAP.

  9. Magellan in transition

    NASA Technical Reports Server (NTRS)

    Doody, Dave

    1993-01-01

    Aerobraking Magellan would provide the possibility of obtaining gravity field data for Venus all the way to the poles. Attempts to accomplish aerobraking, which began on May 25, 1993 in the Magellan Transition Experiment, are discussed.

  10. Oligocyclopentadienyl transition metal complexes

    SciTech Connect

    de Azevedo, Cristina G.; Vollhardt, K. Peter C.

    2002-01-18

    Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.

  11. Transit Timing Variations

    NASA Video Gallery

    The animation shows the difference between planet transit timing of single and multiple planet system. In tightly packed planetary systems, the gravitational pull of the planets among themselves ca...

  12. Stability, transition and turbulence

    NASA Technical Reports Server (NTRS)

    Hussaini, M. Y.

    1987-01-01

    A glimpse is provided of the research program in stability, transition and turbulence based on numerical simulations. This program includes both the so-called abrupt and the restrained transition processes. Attention is confined to the prototype problems of channel flow and the parallel boundary layer in the former category and the Taylor-Couette flow in the latter category. It covers both incompressible flows and supersonic flows. Some representative results are presented.

  13. Stability, transition and turbulence

    NASA Technical Reports Server (NTRS)

    Hussaini, M. Y.

    1987-01-01

    A glimpse is provided of the research program in stability, transition, and turbulence based on numerical simulations. This program includes both the so-called abrupt and the restrained transition processes. Attention is confined to the prototype problems of channel flow and the parallel boundary layer in the former category and the Taylor-Couette flow in the latter category. It covers both incompressible flows and supersonic flows. Some representative results are presented.

  14. Matter in transition

    DOE PAGESBeta

    Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington

    2016-04-13

    In this study, we explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, wheremore » a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU(N) require Weierstrass models that cannot be realized from the standard SU(N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.« less

  15. Venus Transit 2004

    NASA Astrophysics Data System (ADS)

    Mayo, L. A.; Odenwald, S. F.

    2002-09-01

    December 6th, 1882 was the last transit of the planet Venus across the disk of the sun. It was heralded as an event of immense interest and importance to the astronomical community as well as the public at large. There have been only six such occurrences since Galileo first trained his telescope on the heavens in 1609 and on Venus in 1610 where he concluded that Venus had phases like the moon and appeared to get larger and smaller over time. Many historians consider this the final nail in the coffin of the Ptolemaic, Earth centered solar system. In addition, each transit has provided unique opportunities for discovery such as measurement and refinement of the astronomical unit, calculation of longitudes on the earth, and detection of Venus' atmosphere. The NASA Sun Earth Connection Education Forum in partnership with the Solar System Exploration Forum, DPS, and a number of NASA space missions is developing plans for an international education program centered around the June 8, 2004 Venus transit. The transit will be visible in its entirety from Europe and partially from the East Coast of the United States. We will use a series of robotic observatories including the Telescopes In Education network distributed in latitude to provide observations of the transit that will allow middle and high school students to calculate the A.U. through application of parallax. We will also use Venus transit as a probe of episodes in American history (e.g. 1769: revolutionary era, 1882: post civil war era, and 2004: modern era). Museums and planetariums in the US and Europe will offer real time viewing of the transit and conduct educational programs through professional development seminars, public lectures, and planetarium shows. We are interested in soliciting advice from the research community to coordinate professional research interests with this program.

  16. RTGs on Transit

    NASA Astrophysics Data System (ADS)

    Dassoulas, John; McNutt, Ralph L.

    2007-01-01

    Transit, the US Navy's Navigation Satellite System was conceived at the Applied Physics Laboratory in 1957 by observing the Doppler shift while tracking Sputnik I. As spacecraft development proceeded there was concern about the ability of batteries to maintain the hermetic seal over a 5-year operational life requirement; therefore, alternate energy sources were investigated. The radioisotope thermoelectric generator (RTG) concept was pursued and resulted in the launch of SNAP 3s, providing partial power on both Transit 4A and 4B. SNAP 9s provided full power on three Transit 5BNs. All launches occurred in the early 1960s. When the U.S. conducted the high altitude nuclear test from Johnson Island, several spacecraft were lost due to artificial enhancement of charged particles in the Earth's magnetosphere resulting in rapid degradation of solar cell power production. This led to the decision to have both an RTG and Solar cell/battery design for Transit power systems; hence, a new RTG design, with a separable heat source and radiative coupling to the thermoelectric elements, was flown on TRIAD. This pioneering effort provided the impetus for future RTGs on interplanetary spacecraft. This paper describes the origin and purpose of the Transit program and provides details on the five satellites in that program that were powered by the first American RTGs used in space. The rationale and some of the challenges inherent in that use are also described.

  17. Examining hydrogen transitions.

    SciTech Connect

    Plotkin, S. E.; Energy Systems

    2007-03-01

    This report describes the results of an effort to identify key analytic issues associated with modeling a transition to hydrogen as a fuel for light duty vehicles, and using insights gained from this effort to suggest ways to improve ongoing modeling efforts. The study reported on here examined multiple hydrogen scenarios reported in the literature, identified modeling issues associated with those scenario analyses, and examined three DOE-sponsored hydrogen transition models in the context of those modeling issues. The three hydrogen transition models are HyTrans (contractor: Oak Ridge National Laboratory), MARKAL/DOE* (Brookhaven National Laboratory), and NEMS-H2 (OnLocation, Inc). The goals of these models are (1) to help DOE improve its R&D effort by identifying key technology and other roadblocks to a transition and testing its technical program goals to determine whether they are likely to lead to the market success of hydrogen technologies, (2) to evaluate alternative policies to promote a transition, and (3) to estimate the costs and benefits of alternative pathways to hydrogen development.

  18. Materials Data on As2S2O9 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  19. Degradation of florfenicol in water by UV/Na2S 2O 8 process.

    PubMed

    Gao, Yu-Qiong; Gao, Nai-Yun; Deng, Yang; Yin, Da-Qiang; Zhang, Yan-Sen

    2015-06-01

    UV irradiation-activated sodium persulfate (UV/PS) was studied to degrade florfenicol (FLO), a phenicol antibiotic commonly used in aquaculture, in water. Compared with UV/H2O2 process, UV/PS process achieves a higher FLO degradation efficiency, greater mineralization, and less cost. The quantum yield for direct photolysis of FLO and the second-order rate constant of FLO with sulfate radicals were determined. The effects of various factors, namely PS concentration, anions (NO3 (-), Cl(-), and HCO3 (-)), ferrous ion, and humic acid (HA), on FLO degradation were investigated. The results showed that the pseudo-first-order rate constant increased linearly with increased PS concentration. The tested anions all adversely affected FLO degradation performance with the order of HCO3 (-) > Cl(-) > NO3 (-). Coexisting ferrous ions enhanced FLO degradation at a Fe(2+)/PS molar ratio under 1:1. HA significantly inhibited FLO degradation due to radical scavenging and light-screening effect. Toxicity assessment showed that it is capable of controlling the toxicity for FLO degradation. These findings indicated that UV/PS is a promising technology for water polluted by antibiotics, and the treatment is optimized only after the impacts of water characteristics are carefully considered. PMID:25567063

  20. Materials Data on Na2S2O3 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  1. Materials Data on V2S2O11 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Materials Data on Sb2(S2O7)3 (SG:2) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Materials Data on ZnC2S2(OF)6 (SG:148) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. Materials Data on CaC2S2(OF)6 (SG:148) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on P2S2O3 (SG:120) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Transition and laminar instability

    NASA Technical Reports Server (NTRS)

    Mack, L. M.

    1977-01-01

    The linear stability theory was applied to the problem of boundary layer transition in incompressible flow. The theory was put into a form suitable for three-dimensional boundary layers; both the temporal and spatial theories were examined; and a generalized Gaster relation for three-dimensional boundary layers was derived. Numerical examples include the stability characteristics of Falkner-Skan boundary layers, the accuracy of the two-dimensional Gaster relation for these boundary layers, and the magnitude and direction of the group velocity for oblique waves in the Blasius boundary layer. Available experiments which bear on the validity of stability theory and its relation to transition are reviewed and the stability theory is applied to transition prediction. The amplitude method is described in which the wide band disturbance amplitude in the boundary layer is estimated from stability theory and an interaction relation for the initial amplitude density of the most unstable frequency.

  7. Electroweak Phase Transitions

    NASA Astrophysics Data System (ADS)

    Anderson, Gregory Wayne

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles, and completes at a temperature where the order parameter, _ {T}, is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially sensitive function of T. In very minimal extensions of the standard model it is quite easy to increase T so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal extensions of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state = 246 GeV unstable. The requirement that the state = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field. Semi-classical reasoning suggests that, when a particle receives a contribution to its mass from the vacuum expectation value of a scalar, under certain conditions, the ground state of particle number one contains a 'dimple' or shallow scalar field condensate around the particle. We argue that this is not the case. A careful analysis, taking into account quantum mechanics, shows that the semi-classical approximation is a poor one. We find that there are no energetically favored one-particle dimple solutions for perturbative couplings.

  8. Electroweak phase transitions

    SciTech Connect

    Anderson, G.W.

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l angle}{phi}{r angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l angle}{phi}{r angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l angle}{phi}{r angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l angle}{phi}{r angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l angle}{phi}{r angle} = 246 GeV unstable. The requirement that the state {l angle}{phi}{r angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  9. Electroweak phase transitions

    SciTech Connect

    Anderson, G.W.

    1991-09-16

    An analytic treatment of the one Higgs doublet, electroweak phase transition is given. The phase transition is first order, occurs by the nucleation of thin walled bubbles and completes at a temperature where the order parameter, {l_angle}{phi}{r_angle}{sub T} is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon number violation is an exponentially function of {l_angle}{phi}{r_angle}{sub T}. In very minimal extensions of the standard model it is quite easy to increase {l_angle}{phi}{r_angle}{sub T} so that anomalous baryon number violation is suppressed after completion of the phase transition. Hence baryogenesis at the electroweak phase transition is tenable in minimal of the standard model. In some cases additional phase transitions are possible. For a light Higgs boson, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value {l_angle}{phi}{r_angle} = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state {l_angle}{phi}{r_angle} = 246 GeV unstable. The requirement that the state {l_angle}{phi}{r_angle} = 246 GeV is sufficiently long lived constrains the masses of the Higgs boson and the top quark. Finally, we consider whether local phase transitions can be induced by heavy particles which act as seeds for deformations in the scalar field.

  10. [Transition in diabetology].

    PubMed

    Hauschild, M; Elowe-Gruau, E; Dwyer, A; Aquarone, M-P; Unal, S; Jornayvaz, F R; Perrenoud, L; Gastaldi, G; Castellsague, M; Dirlewanger, M; Schwitzgebel, V M

    2015-02-18

    For patients with type I diabetes, transition from pediatric to adult care is a challenge due to complex treatment requirements and the physical, psychological and social changes of adolescence. Members of the care team must recognize that while these emerging adults need to develop self-management skills, this may conflict at times with the developmentally appropriate desire for increasing autonomy. The role of nursing in coordinating a successful transition is critical for maintaining continuity of patient-centered care that responds to the specific needs of these young adults. PMID:25915986

  11. Network Observability Transitions

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Wang, Jianhui; Motter, Adilson E.

    2012-12-01

    In the modeling, monitoring, and control of complex networks, a fundamental problem concerns the comprehensive determination of the state of the system from limited measurements. Using power grids as example networks, we show that this problem leads to a new type of percolation transition, here termed a network observability transition, which we solve analytically for the configuration model. We also demonstrate a dual role of the network’s community structure, which both facilitates optimal measurement placement and renders the networks substantially more sensitive to “observability attacks.” Aside from their immediate implications for the development of smart grids, these results provide insights into decentralized biological, social, and technological networks.

  12. UTM: Universal Transit Modeller

    NASA Astrophysics Data System (ADS)

    Deeg, Hans J.

    2014-12-01

    The Universal Transit Modeller (UTM) is a light-curve simulator for all kinds of transiting or eclipsing configurations between arbitrary numbers of several types of objects, which may be stars, planets, planetary moons, and planetary rings. A separate fitting program, UFIT (Universal Fitter) is part of the UTM distribution and may be used to derive best fits to light-curves for any set of continuously variable parameters. UTM/UFIT is written in IDL code and its source is released in the public domain under the GNU General Public License.

  13. Electron impact excitation of Mg VIII . Collision strengths, transition probabilities and theoretical EUV and soft X-ray line intensities for Mg VIII

    NASA Astrophysics Data System (ADS)

    Grieve, M. F. R.; Ramsbottom, C. A.; Keenan, F. P.

    2013-08-01

    Context. Mg viii emission lines are observed in a range of astronomical objects such as the Sun, other cool stars and in the coronal line region of Seyfert galaxies. Under coronal conditions Mg viii emits strongly in the extreme ultraviolet (EUV) and soft X-ray spectral regions which makes it an ideal ion for plasma diagnostics. Aims: Two theoretical atomic models, consisting of 125 fine structure levels, are developed for the Mg viii ion. The 125 levels arise from the 2s22p, 2s2p2, 2p3, 2s23s, 2s23p, 2s23d, 2s2p3s, 2s2p3p, 2s2p3d, 2p23s, 2p23p and 2p23d configurations. Electron impact excitation collision strengths and radiative transition probabilities are calculated for both Mg viii models, compared with existing data, and the best model selected to generate a set of theoretical emission line intensities. The EUV lines, covering 312-790 Å, are compared with existing solar spectra (SERTS-89 and SUMER), while the soft X-ray transitions (69-97 Å) are examined for potential density diagnostic line ratios and also compared with the limited available solar and stellar observational data. Methods: The R-matrix codes Breit-Pauli RMATRXI and RMATRXII are utilised, along with the PSTGF code, to calculate the collision strengths for two Mg viii models. Collision strengths are averaged over a Maxwellian distribution to produce the corresponding effective collision strengths for use in astrophysical applications. Transition probabilities are also calculated using the CIV3 atomic structure code. The best data are then incorporated into the modelling code CLOUDY and line intensities generated for a range of electron temperatures and densities appropriate to solar and stellar coronal plasmas. Results: The present effective collision strengths are compared with two previous calculations. Good levels of agreement are found with the most recent, but there are large differences with the other for forbidden transitions. The resulting line intensities compare favourably with the

  14. Radiative transitions involving the (2p2)(3 Pe) metastable autodetaching of H(-)

    NASA Technical Reports Server (NTRS)

    Jacobs, V. L.; Bhatia, A. K.; Temkin, A.

    1974-01-01

    The absorption coefficient for the free-bound transition H (ls) + e(-)+ h omega yields H(-)(2 sq p,(3)P(e)) is calculated (together with the differential emission rate for the inverse process) using ls - 2s - 2p close coupling continuum wave functions and a Hylleraas bound state wave function. A maximum in the absorption and emission spectra is found to occur at a photon wavelength of 1219.5 A, which is 2 A closer to the Lyman alpha line than predicted by the calculations of Drake, and is in closer agreement with the stellar absorption feature identified by Heap and Stecher. The free-bound absorption process appears to be a significant source of continuous ultraviolet opacity.

  15. Spectral lines behavior of Be I and Na I isoelectronic sequence in Debye plasma environment

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Rajat K.; Chattopadhyay, Sudip; Sinha Mahapatra, Uttam

    2012-08-01

    We report the plasma screening effect on the first ionization potential (IP) and [He]2s2(1S0)→[He]2s2p /2s3p allowed (P11) and inter-combination transitions (P31) in some selected Be-like ions. In addition, we investigate the spectral properties of [Ne]3s (2S1/2)→[Ne]np(2P1/2 and P23/2 for n = 3, 4) transitions in Ca X and Fe XVI ions (Na I isoelectronic sequence) and [He]3s(2S1/2)→[He]np(2P1/2 and P23/2 for n = 2, 3) transitions in Li, B II, and N IV (Li I isoelectronic sequence) under plasma environment. The state-of-the-art relativistic coupled cluster calculations using the Debye model of plasma for electron-nucleus interaction show that (a) the ionization potential decreases sharply with increasing plasma strength and (b) the gap between the [He]2s2(1S0)→[He]2s2p(1,3P1) energy levels increases with increasing plasma potential and nuclear charge. It is found that the [He]2s2 (1S0)→2s3p(1,3P1) transition energy decreases uniformly with increasing plasma potential and nuclear charge. In other words, the spectral lines associated with 2s-2p (i.e., Δn=0, where n corresponds to principle quantum number) transitions in Be I isoelectronic sequence exhibit a blue-shift (except for Be I, B II, and the lowest inter-combination line in C III, which exhibit a red-shift), whereas those associated with 2s-3p (i.e., Δn≠0) transitions are red-shifted. Similar trend is observed in Li I and Na I isoelectronic sequences, where spectral lines associated with Δn=0 (Δn≠0) are blue-shifted (red-shifted). The effect of Coulomb screening on the spectral lines of ions subjected to plasma is also addressed.

  16. Tips for Transition

    ERIC Educational Resources Information Center

    Kellems, Ryan O.; Morningstar, Mary E.

    2010-01-01

    The Individuals With Disabilities Education Improvement Act of 2004 (IDEA) states that transition planning should begin at the earliest age appropriate and no later than age 16. IDEA requires schools to make collaborative efforts to provide students access to an array of postschool activities including integrated employment, postsecondary…

  17. Nursing Role Transition Preceptorship

    ERIC Educational Resources Information Center

    Batory, Susan M.

    2014-01-01

    The preceptorship clinical experience in a practical nursing (PN) program at a Midwestern community college is considered crucial to the PN students' transition from novice nurse to professional nurse. However, no research has been available to determine whether the preceptorship clinical accomplishes its purpose. A case study was conducted to…

  18. A Transiting Jupiter Analog

    NASA Astrophysics Data System (ADS)

    Kipping, D. M.; Torres, G.; Henze, C.; Teachey, A.; Isaacson, H.; Petigura, E.; Marcy, G. W.; Buchhave, L. A.; Chen, J.; Bryson, S. T.; Sandford, E.

    2016-04-01

    Decadal-long radial velocity surveys have recently started to discover analogs to the most influential planet of our solar system, Jupiter. Detecting and characterizing these worlds is expected to shape our understanding of our uniqueness in the cosmos. Despite the great successes of recent transit surveys, Jupiter analogs represent a terra incognita, owing to the strong intrinsic bias of this method against long orbital periods. We here report on the first validated transiting Jupiter analog, Kepler-167e (KOI-490.02), discovered using Kepler archival photometry orbiting the K4-dwarf KIC-3239945. With a radius of (0.91+/- 0.02) {R}{{J}}, a low orbital eccentricity ({0.06}-0.04+0.10), and an equilibrium temperature of (131+/- 3) K, Kepler-167e bears many of the basic hallmarks of Jupiter. Kepler-167e is accompanied by three Super-Earths on compact orbits, which we also validate, leaving a large cavity of transiting worlds around the habitable-zone. With two transits and continuous photometric coverage, we are able to uniquely and precisely measure the orbital period of this post snow-line planet (1071.2323 ± 0.0006d), paving the way for follow-up of this K = 11.8 mag target.

  19. Youth Policy in Transition.

    ERIC Educational Resources Information Center

    Timpane, Michael; And Others

    A study team was commissioned to critically review three independent reports on youth and schooling: "Youth: Transition to Adulthood"; "The Education of Adolescents"; and "The Reform of Secondary Education." The study team examined the reports in light of the most recent available social science evidence. The three reports, presenting similar…

  20. Transition at hypersonic speeds

    NASA Technical Reports Server (NTRS)

    Morkovin, Mark V.

    1987-01-01

    Certain conjectures on the physics of instabilities in high-speed flows are discussed and the state of knowledge of hypersonic transition summarized. The case is made for an unpressured systematic research program in this area consisting of controlled microscopic experiments, theory, and numerical simulations.

  1. A Survey Transition Course

    ERIC Educational Resources Information Center

    Johnston, William; McAllister, Alex M.

    2012-01-01

    Successful outcomes for a "Transition Course in Mathematics" have resulted from two unique design features. The first is to run the course as a "survey course" in mathematics, introducing sophomore-level students to a broad set of mathematical fields. In this single mathematics course, undergraduates benefit from an introduction of proof…

  2. Variational transition state theory

    SciTech Connect

    Truhlar, D.G.

    1993-12-01

    This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.

  3. Immigration and Adult Transitions

    ERIC Educational Resources Information Center

    Rumbaut, Ruben G.; Komaie, Golnaz

    2010-01-01

    Almost 30 percent of the more than 68 million young adults aged eighteen to thirty-four in the United States today are either foreign born or of foreign parentage. As these newcomers make their transitions to adulthood, say Ruben Rumbaut and Golnaz Komaie, they differ significantly not only from one another but also from their native-parentage…

  4. String mediated phase transitions

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Haws, D.; Rivers, R.; Holbraad, S.

    1988-01-01

    It is demonstrated from first principles how the existence of string-like structures can cause a system to undergo a phase transition. In particular, the role of topologically stable cosmic string in the restoration of spontaneously broken symmetries is emphasized. How the thermodynamic properties of strings alter when stiffness and nearest neighbor string-string interactions are included is discussed.

  5. Families in Transition .

    ERIC Educational Resources Information Center

    Bundy, Michael L., Ed.; Gumaer, James, Ed.

    1984-01-01

    Focuses on disrupted families and the role of the school counselor in helping children adjust. Describes characteristics of healthy families, and discusses the transition to the blended family, effects of divorce groups on children's classroom behavior, counseling children in stepfamilies, single-parent families, and parenting strengths of single…

  6. Singing Smoothes Classroom Transitions

    ERIC Educational Resources Information Center

    Mathews, Sarah E.

    2012-01-01

    Just as humming a merry tune helped Snow White and her furry animal friends to quickly clean a filthy cottage in the movie "Snow White and the Seven Dwarfs" (Disney & Cottrell, 1937), singing can be an effective way to help keep young children fully engaged during classroom transitions. The purposes of this article are to: (1) consider why…

  7. Learning for Life Transitions

    ERIC Educational Resources Information Center

    Varmecky, Jane Hyde

    2012-01-01

    Many adults return to formal learning situations to pursue lifelong learning goals because their lives are in transition from dealing with real-life problems such as divorce and re-marriage. The purpose of this study was to describe what couples learned that contributed to the success of their subsequent marriages and how they learned it. The…

  8. Transition probability of the Si III 189.2-nm intersystem line

    NASA Technical Reports Server (NTRS)

    Kwong, H. S.; Johnson, B. C.; Smith, P. L.; Parkinson, W. H.

    1983-01-01

    Measurement of the lifetime of the metastable 3s3p(3)P(0)1 level of Si(2+) (Si III), which decays by photon emission at 189.2 nm to the 3s2(1)S0 state, is reported. The data were taken from spontaneous emission from metastable Si III stored in an RF ion trap. The Si III ions were produced through electron bombardment of SiH4 and SiF4 at pressures of 1/100,000,000-1/10,000,000 Torr. A photomultiplier was employed to count the photon emissions from the transitions. A total of 11 decay curves were generated for analysis, with Poisson statistics used to set the uncertainties at within 8 pct. Significant systematic effects were controlled, and the lifetime was found to be within 3.6 microsec of 59.9 microsec. The method used is concluded valid for determining the lifetimes of metastable levels of low-Z ions with low charge, and thereby the transition probabilities.

  9. Transit of Extrasolar Planets

    NASA Technical Reports Server (NTRS)

    Doyle, Laurance R.

    1998-01-01

    During the past five years we have pursued the detection of extrasolar planets by the photometric transit method, i.e. the detection of a planet by watching for a drop in the brightness of the light as it crosses in front of a star. The planetary orbit must cross the line-of-sight and so most systems will not be lined up for such a transit to ever occur. However, we have looked at eclipsing binary systems which are already edge-on. Such systems must be very small in size as this makes the differential light change due to a transit much greater for a given planet size (the brightness difference will be proportional to the area of the transiting planet to the disc area of the star). Also, the planet forming region should be closer to the star as small stars are generally less luminous (that is, if the same thermal regime for planet formation applies as in the solar system). This led to studies of the habitable zone around other stars, as well. Finally, we discovered that our data could be used to detect giant planets without transits as we had been carefully timing the eclipses of the stars (using a GPS antenna for time) and this will drift by being offset by any giant planets orbiting around the system, as well. The best summary of our work may be to just summarize the 21 refereed papers produced during the time of this grant. This will be done is chronological order and in each section separately.

  10. The Mongolia experience: transitioning within transition.

    PubMed

    MacKenzie, Richard G

    2009-12-01

    Although Mongolia has a long and distinguished history, as a new and emerging democracy it is experiencing the pains of transition-one that is moving the country from its pastoral and nomadic past into the 21st century. Confounded by its previous dependence on socialist Soviet Russia, the concept of a market economy seems opportunistic for some, while for those living within the traditional lifestyle of the herdsman in the countryside it is confusing and threatening to family structure and values. Adolescents and young adults are caught at the interface-not only of their own development, but by the disparities between tradition and Western values, new technology, and freedoms granted by the emerging democracy, and by the civic practice of democracy itself. Conceptually the new belongs to the young, and yet limited health and educational resources are available to modulate and focus both threats and opportunities. Using the analogy of the spirit banner of the warrior, it is the young as the warriors of the 21st century who have the energy and investment in the future that will be needed to shepherd this change. Both personal and public health, within the context of development, the psychobiological model, and the political and social ecology will be strong determinants of success. It is a parallel investment in both youth and the ideals they represent that will ensure success for the new Mongolia. PMID:20653216

  11. Alternative fuel transit buses: The Pierce Transit Success Story

    SciTech Connect

    1996-10-01

    The Pierce transit program for operating mass transit buses on compressed natural gas (CNG) is described. Cost, reliability, fuel efficiency, emission of combustion products, and future trends are discussed.

  12. Transition Planning: A Team Effort. NICHCY Transition Summary, TS10.

    ERIC Educational Resources Information Center

    Gutierrez, Mary Kate

    This summary on transition planning provides ideas and information on how students, families, school personnel, service providers, and others can work together to help students with a disability make a smooth transition after leaving high school. It focuses on creative transition planning and services that use all the resources that exist in…

  13. Models for transition clinics.

    PubMed

    Carrizosa, Jaime; An, Isabelle; Appleton, Richard; Camfield, Peter; Von Moers, Arpad

    2014-08-01

    Transition is a purposeful, planned process that addresses the medical, psychosocial, educational, and vocational needs of adolescents and young adults with chronic medical conditions, as they advance from a pediatric and family-centered to an adult, individual focused health care provider. This article describes some of the models for transition clinics or services for epilepsy in five countries (Canada, France, Colombia, Germany, and the United Kingdom). These models include joint adult and pediatric clinics, algorithm-driven service, and a check list system in the context of pediatric care. Evaluation of these models is limited, and it is not possible to choose an optimal program. The attitude and motivation of health care providers may be the most important elements. PMID:25209087

  14. Collapse transition in proteins.

    PubMed

    Ziv, Guy; Thirumalai, D; Haran, Gilad

    2009-01-01

    The coil-globule transition, a tenet of the physics of polymers, has been identified in recent years as an important unresolved aspect of the initial stages of the folding of proteins. We describe the basics of the collapse transition, starting with homopolymers and continuing with proteins. Studies of denatured-state collapse under equilibrium are then presented. An emphasis is placed on single-molecule fluorescence experiments, which are particularly useful for measuring properties of the denatured state even under conditions of coexistence with the folded state. Attempts to understand the dynamics of collapse, both theoretically and experimentally, are then described. Only an upper limit for the rate of collapse has been obtained so far. Improvements in experimental and theoretical methodology are likely to continue to push our understanding of the importance of the denatured-state thermodynamics and dynamics for protein folding in the coming years. PMID:19081910

  15. High speed transition prediction

    NASA Technical Reports Server (NTRS)

    Gasperas, Gediminis

    1993-01-01

    The main objective of this work period was to develop, maintain and exercise state-of-the-art methods for transition prediction in supersonic flow fields. Basic state and stability codes, acquired during the last work period, were exercised and applied to calculate the properties of various flowfields. The development of a code for the prediction of transition location using a currently novel method (the PSE or Parabolized Stability Equation method), initiated during the last work period and continued during the present work period, was cancelled at mid-year for budgetary reasons. Other activities during this period included the presentation of a paper at the APS meeting in Tallahassee, Florida entitled 'Stability of Two-Dimensional Compressible Boundary Layers', as well as the initiation of a paper co-authored with H. Reed of the Arizona State University entitled 'Stability of Boundary Layers'.

  16. Transitions: exploring the frontier.

    PubMed

    Corless, Inge B

    End-of-life experiences go by various terms, including near-death experiences (NDEs), death bed visions, death bed phenomena, death bed coincidences, and nearing death awareness. Death bed escorts is the term applied to the vision of deceased family members or friends who inform the dying person that they will be accompanied in the transition from life. In this article, I examine the subject of NDEs and death bed escorts, starting with the rich body of work provided by Robert and Beatrice Kastenbaum. A subject of some interest to Robert Kastenbaum, he explored this frontier in his many writings on dying, death, and bereavement. Ever the pioneer and having made the ultimate transition, he may yet be exploring new frontiers. PMID:25351590

  17. Emergence and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Sikkema, Arnold

    2006-05-01

    Phase transitions are well defined in physics through concepts such as spontaneous symmetry breaking, order parameter, entropy, and critical exponents. But emergence --- also exhibiting whole-part relations (such as top-down influence), unpredictability, and insensitivity to microscopic detail --- is a loosely-defined concept being used in many disciplines, particularly in psychology, biology, philosophy, as well as in physics[1,2]. I will review the concepts of emergence as used in the various fields and consider the extent to which the methods of phase transitions can clarify the usefulness of the concept of emergence both within the discipline of physics and beyond.1. Robert B. Laughlin, A Different Universe: Reinventing Physics from the Bottom Down (New York: Basic Books, 2005). 2. George F.R. Ellis, ``Physics and the Real World'', Physics Today, vol. 58, no. 7 (July 2005) pp. 49-54.

  18. Radiative Transitions in Charmonium

    SciTech Connect

    Jozef Dudek; Robert Edwards; David Richards

    2005-10-01

    The form factors for the radiative transitions between charmonium mesons are investigated. We employ an anisotropic lattice using a Wilson gauge action, and domain-wall fermion action. We extrapolate the form factors to Q{sup 2} = 0, corresponding to a real photon, using quark-model-inspired functions. Finally, comparison is made with photocouplings extracted from the measured radiative widths, where known. Our preliminary results find photocouplings commensurate with these experimentally extracted values.

  19. Transition Region Flows

    NASA Astrophysics Data System (ADS)

    Brekke, P.; Murdin, P.

    2000-11-01

    Ultraviolet emission lines emitted from the SOLAR TRANSITION REGION are often shifted from their expected rest wavelengths. Shifts of spectral lines are due to the so-called DOPPLER EFFECT, where the source of emission is moving either away from or towards the observer, causing a change in the apparent wavelength. The shifted emission lines are most often interpreted as a flow of plasma along ...

  20. Kondo-Anderson transitions

    NASA Astrophysics Data System (ADS)

    Kettemann, S.; Mucciolo, E. R.; Varga, I.; Slevin, K.

    2012-03-01

    Dilute magnetic impurities in a disordered Fermi liquid are considered close to the Anderson metal-insulator transition (AMIT). Critical power-law correlations between electron wave functions at different energies in the vicinity of the AMIT result in the formation of pseudogaps of the local density of states. Magnetic impurities can remain unscreened at such sites. We determine the density of the resulting free magnetic moments in the zero-temperature limit. While it is finite on the insulating side of the AMIT, it vanishes at the AMIT, and decays with a power law as function of the distance to the AMIT. Since the fluctuating spins of these free magnetic moments break the time-reversal symmetry of the conduction electrons, we find a shift of the AMIT, and the appearance of a semimetal phase. The distribution function of the Kondo temperature TK is derived at the AMIT, in the metallic phase, and in the insulator phase. This allows us to find the quantum phase diagram in an external magnetic field B and at finite temperature T. We calculate the resulting magnetic susceptibility, the specific heat, and the spin relaxation rate as a function of temperature. We find a phase diagram with finite-temperature transitions among insulator, critical semimetal, and metal phases. These new types of phase transitions are caused by the interplay between Kondo screening and Anderson localization, with the latter being shifted by the appearance of the temperature-dependent spin-flip scattering rate. Accordingly, we name them Kondo-Anderson transitions.

  1. Stimulated coherent transition radiation

    SciTech Connect

    Hung-chi Lihn

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed.

  2. NASA metric transition plan

    NASA Astrophysics Data System (ADS)

    NASA science publications have used the metric system of measurement since 1970. Although NASA has maintained a metric use policy since 1979, practical constraints have restricted actual use of metric units. In 1988, an amendment to the Metric Conversion Act of 1975 required the Federal Government to adopt the metric system except where impractical. In response to Public Law 100-418 and Executive Order 12770, NASA revised its metric use policy and developed this Metric Transition Plan. NASA's goal is to use the metric system for program development and functional support activities to the greatest practical extent by the end of 1995. The introduction of the metric system into new flight programs will determine the pace of the metric transition. Transition of institutional capabilities and support functions will be phased to enable use of the metric system in flight program development and operations. Externally oriented elements of this plan will introduce and actively support use of the metric system in education, public information, and small business programs. The plan also establishes a procedure for evaluating and approving waivers and exceptions to the required use of the metric system for new programs. Coordination with other Federal agencies and departments (through the Interagency Council on Metric Policy) and industry (directly and through professional societies and interest groups) will identify sources of external support and minimize duplication of effort.

  3. NASA metric transition plan

    NASA Technical Reports Server (NTRS)

    1992-01-01

    NASA science publications have used the metric system of measurement since 1970. Although NASA has maintained a metric use policy since 1979, practical constraints have restricted actual use of metric units. In 1988, an amendment to the Metric Conversion Act of 1975 required the Federal Government to adopt the metric system except where impractical. In response to Public Law 100-418 and Executive Order 12770, NASA revised its metric use policy and developed this Metric Transition Plan. NASA's goal is to use the metric system for program development and functional support activities to the greatest practical extent by the end of 1995. The introduction of the metric system into new flight programs will determine the pace of the metric transition. Transition of institutional capabilities and support functions will be phased to enable use of the metric system in flight program development and operations. Externally oriented elements of this plan will introduce and actively support use of the metric system in education, public information, and small business programs. The plan also establishes a procedure for evaluating and approving waivers and exceptions to the required use of the metric system for new programs. Coordination with other Federal agencies and departments (through the Interagency Council on Metric Policy) and industry (directly and through professional societies and interest groups) will identify sources of external support and minimize duplication of effort.

  4. Transition mixing study

    NASA Technical Reports Server (NTRS)

    Reynolds, R.; White, C.

    1986-01-01

    A computer model capable of analyzing the flow field in the transition liner of small gas turbine engines is developed. A FORTRAN code has been assembled from existing codes and physical submodels and used to predict the flow in several test geometries which contain characteristics similar to transition liners, and for which experimental data was available. Comparisons between the predictions and measurements indicate that the code produces qualitative results but that the turbulence models, both K-E and algebraic Reynolds Stress, underestimate the cross-stream diffusion. The code has also been used to perform a numerical experiment to examine the effect of a variety of parameters on the mixing process in transition liners. Comparisons illustrate that geometries with significant curvature show a drift of the jet trajectory toward the convex wall and weaker wake region vortices and decreased penetration for jets located on the convex wall of the liner, when compared to jets located on concave walls. Also shown were the approximate equivalency of angled slots and round holes and a technique by which jet mixing correlations developed for rectangular channels can be used for can geometries.

  5. Oscillator strengths and radiative decay rates for spin-changing S-P transitions in helium: finite nuclear mass effects

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Schulhoff, Eva E.; Drake, G. W. F.

    2015-12-01

    We have calculated the electric dipole (E1) and magnetic quadrupole (M2) oscillator strengths and spontaneous decay rates for 24 spin-changing transitions of atomic helium. We included the effects of the finite nuclear mass and the anomalous magnetic moment of the electron augmented by the recently derived Pachucki term. The specific transitions for 4He are n{ }1{{{S}}}0-{n}\\prime { }3{{{P}}}{1,2} and n{ }3{{{S}}}1-{n}\\prime { }1{{{P}}}1 with n,{n}\\prime ≤slant 3 and n≤slant 10 for {n}\\prime =n. For the E1 calculations we used the Breit approximation and pseudostate expansions to perform the perturbation sums over intermediate states in both the length and velocity gauge as a check on both numerical accuracy and validity of the transition operators. The corrections for the nuclear mass and the electron anomaly tend to cancel, indicating that if one is included, then so should be the other. The tables give mass- and anomaly-dependent coefficients permitting the easy generation of results for the other isotopes of helium.

  6. The Myths of Mass Transit.

    ERIC Educational Resources Information Center

    Burke, Catherine G.

    1982-01-01

    Criticizes eight commonly held notions about the value of mass transit systems in public transportation programs. Alternative approaches for improving the quality and quantity of urban transit systems are discussed. (AM)

  7. Youths Transitioning as Adult Learners

    ERIC Educational Resources Information Center

    Davis, C. Amelia

    2014-01-01

    This chapter considers how transitions to adulthood have been historically represented and presents alternative ways of thinking about transitions to adulthood through the context of adult basic education programs.

  8. The transition to agricultural sustainability

    PubMed Central

    Ruttan, Vernon W.

    1999-01-01

    The transition to sustainable growth in agricultural production during the 21st century will take place within the context of a transition to a stable population and a possible transition to a stable level of material consumption. If the world fails to successfully navigate a transition to sustainable growth in agricultural production, the failure will be due more to a failure in the area of institutional innovation than to resource and environmental constraints. PMID:10339524

  9. Visual Analytics Technology Transition Progress

    SciTech Connect

    Scholtz, Jean; Cook, Kristin A.; Whiting, Mark A.; Lemon, Douglas K.; Greenblatt, Howard

    2009-09-23

    The authors provide a description of the transition process for visual analytic tools and contrast this with the transition process for more traditional software tools. This paper takes this into account and describes a user-oriented approach to technology transition including a discussion of key factors that should be considered and adapted to each situation. The progress made in transitioning visual analytic tools in the past five years is described and the challenges that remain are enumerated.

  10. K-shell energy levels and radiative rates for transitions in Si ix

    NASA Astrophysics Data System (ADS)

    Wei, H. G.; Shi, J. R.; Wang, F. L.; Zhong, J. Y.; Liang, G. Y.; Zhao, G.

    2014-06-01

    Context. Accurate atomic data are needed to analyze the Si ix K-shell features in astrophysical X-ray spectra. Relative large discrepancies in the existing atomic data have impeded this progress. Aims: We present the accurate Si ix K-shell transition data, including K-shell energy levels, wavelengths, radiative rates, and oscillator strengths. Methods: The flexible atomic code (FAC), which is a fully relativistic atomic code with configuration interaction (CI) included, was employed to calculate these data. To investigate the CI effects, calculations with different configurations included were carried out. Results: The K-shell atomic data of Si ix transitions between 1s22s22p2, 1s22s2p3, 1s22p4, 1s2s22p3, 1s2s2p4, and 1s2p5 are reported. The accuracy of our data is demonstrated by comparing them with the available experimental measurements and theoretical calculations. The energy levels are accurate to 3.5 eV, the wavelengths to within 15 mÅ. For most transitions, the radiative rates an accuracy of 20%. The effects of CI from high-energy configurations were investigated as well. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A105

  11. Quantum-Classical Phase Transition of the Escape Rate of Two-Sublattice Antiferromagnetic Large Spins

    NASA Astrophysics Data System (ADS)

    Owerre, Solomon Akaraka; Paranjape, M. B.

    2014-11-01

    The Hamiltonian of a two-sublattice antiferromagnetic spins, with single (hard-axis) and double ion anisotropies described by H = J {\\hat S}1...\\hatS 2-2Jz \\hat {S}1z\\hat {S}2z+K(\\hat {S}1z2 +\\hat {S}2z2) is investigated using the method of effective potential. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and reduced mass. We study the quantum-classical phase transition of the escape rate of this model. We show that the first-order phase transition for this model sets in at the critical value Jc = (Kc+Jz, c)/2 while for the anisotropic Heisenberg coupling H = J(S1xS2x +S1yS2y) + JzS1zS2z + K(S1z2+ S2z2) we obtain Jc = (2Kc-Jz, c)/3. The phase diagrams of the transition are also studied.

  12. Reconstructing Transition Knowledge in Taiwan

    ERIC Educational Resources Information Center

    Cheng, Chen-chen

    2012-01-01

    Taking a post-colonial stand and using school to work transition as an example, the author re-examines the special education discourses in Taiwan and attempts to construct alternate understandings of transition from sociological and cultural perspectives. A review of past transition literature and a survey of the educational background of the…

  13. Slow Transit Constipation.

    PubMed

    Wald, Arnold

    2002-08-01

    The diagnosis of slow transit functional constipation is based upon diagnostic testing of patients with idiopathic constipation who responded poorly to conservative measures such as fiber supplements, fluids, and stimulant laxatives. These tests include barium enema or colonoscopy, colonic transit of radio-opaque markers, anorectal manometry, and expulsion of a water-filled balloon. Plain abdominal films can identify megacolon, which can be further characterized by barium or gastrografin studies. Colonic transit of radio-opaque markers identifies patients with slow transit with stasis of markers in the proximal colon. However, anorectal function should be characterized to exclude outlet dysfunction, which may coexist with colonic inertia. Because slow colonic transit is defined by studies during which patients consume a high-fiber diet, fiber supplements are generally not effective, nor are osmotic laxatives that consist of unabsorbed sugars. Stimulant laxatives are considered first-line therapy, although studies often show a diminished colonic motor response to such agents. There is no evidence to suggest that chronic use of such laxatives is harmful if they are used two to three times per week. Polyethylene glycol with or without electrolytes may be useful in a minority of patients, often combined with misoprostol. I prefer to start with misoprostol 200 mg every other morning and increase to tolerance or efficacy. I see no advantage in prescribing misoprostol on a TID or QID basis or even daily because it increases cramping unnecessarily. This drug is not acceptable in young women who wish to become pregnant. An alternative may be colchicine, which is reported to be effective when given as 0.6 mg TID. Long-term efficacy has not been studied. Finally, biofeedback is a risk-free approach that has been reported as effective in approximately 60% of patients with slow transit constipation in the absence of outlet dysfunction. Although difficult to understand

  14. Alameda-Contra Costa Transit District (AC Transit) Fuel Cell Transit Buses: Preliminary Evaluation Results

    SciTech Connect

    Chandler, K.; Eudy, L.

    2007-03-01

    This report provides an evaluation of three prototype fuel cell-powered transit buses operating at AC Transit in Oakland, California, and six baseline diesel buses similar in design to the fuel cell buses.

  15. VizieR Online Data Catalog: Energies & radiative transition from ArXII to ZnXXIV (Wang+, 2016)

    NASA Astrophysics Data System (ADS)

    Wang, K.; Si, R.; Dang, W.; Jonsson, P.; Guo, X. L.; Li, S.; Chen, Z. B.; Zhang, H.; Long, F. Y.; Liu, H. T.; Li, D. F.; Hutton, R.; Chen, C. Y.; Yan, J.

    2016-04-01

    Combined relativistic configuration interaction and many-body perturbation calculations are performed for the 359 fine-structure levels of the 2s22p3, 2s2p4, 2p5, 2s22p23l, 2s2p33l, 2p43l, and 2s22p24l configurations in N-like ions from Ar XII to Zn XXIV. Complete and consistent data sets of energies, wavelengths, radiative rates, oscillator strengths, and line strengths for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 359 levels are given for each ion. The present work significantly increases the amount of accurate data for ions in the nitrogen-like sequence, and the accuracy of the energy levels is high enough to enable the identification and interpretation of observed spectra involving the n=3, 4 levels, for which experimental values are largely scarce. Meanwhile, the results should be of great help for modeling and diagnosing astrophysical and fusion plasmas. (2 data files).

  16. Dimensional reduction transition

    SciTech Connect

    Kolb, E.

    1984-11-01

    In this conference on phase transitions in the early Universe the author discusses the transition from more than four space-time dimensions to four effective space-time dimensions; the dimensional reduction transition. The basic assumption is that the true dimensionality of space-time is more than four, and that at present the extra dimensions are compact and too small to be observable. The origin of the observed gauge symmetries from symmetries of a compact space has been proposed as a possible approach for the unification of particle physics and gravity. The common assumption in all models with extra dimensions is that the unseen dimensions are compactified to a very small size, usually taken to be of the order of the Planck length. To probe the structure of the extra dimensions would require energies of the Planck mass E = m/sub pl/ = 1.2 x 10/sup 19/GeV, and the early Universe may be the only source of such energies. The author will assume for initial conditions that all spatial dimensions are small, and that initially the Universe had N = 3 + D spatial dimensions. When the temperature fell below T = R/sub D//sup -1/, where R/sub D/ is the physical size of the compact extra dimensions, the space-time dimensionality of the Universe underwent a reduction to effectively a 4 space-time dimensional Universe, and dynamical effects of the extra dimensions became unimportant. In this paper I will discuss three possible consequences of this cosmological dimensional reduction; entropy production (inflation), magnetic monopole production, and stable, massive particle production. 14 refs., 4 figs.

  17. Transition Metal Switchable Mirror

    SciTech Connect

    2009-01-01

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm

  18. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2010-01-08

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  19. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2013-05-29

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm

  20. Global transition in health.

    PubMed

    Bygbjerg, Ib Christian; Meyrowitsch, Dan W

    2007-02-01

    "Tempora mutantur et nos in illis" King Lothar I remarked by year 900 AD. What exactly changed in us over time, i.e. how patterns of the epidemiological transition in populations locally and globally might appear, was described by Omran in 1971 [1]. The effect of transition on health and diseases in populations was demonstrated by Frenkl et al in 1991 [2]. And which major public health problems following each other, and why, was underscored by LaPorte in 1995 [3]. In 2000, leaders of the world society decided to identify a range of common goals, the Millennium Development Goals (MDG), to be reached by year 2015. Many of the MDG are directly or indirectly related with the major health problems, particularly those hitting the poorest: lack of clean drinking water, unhealthy environment, high maternal mortality due to lack of care for the pregnant, and lack of control of major communicable, often fatal diseases like child diseases, malaria, HIV/AIDS and tuberculosis. It is remarkable that the specific chronic diseases of major public health relevance are in fact not mentioned in the MDG, even if these diseases increasingly are hitting populations in low- and middle-income societies, i.e. developing countries. The world community seems to prioritize the diseases that are most visible, and most often linked with poverty, namely the infectious diseases mentioned above, which together kill about 17 million people annually, often in combination with malnutrition, and the 0.6 million deaths related to birth and pregnancy. With the exception of HIV/AIDS, which also hit richer societies, these diseases of poverty have been under-prioritized regarding research as well. However, at the turn of the Millennium, the burden of "Western" non-communicable diseases was increasing fast in developing countries. And by 2025, the burden of non-communicable diseases is expected to have doubled globally, with half of the burden on developing countries. Therefore it may be rewarding to look

  1. Electromagnetic transitions in hypernuclei

    SciTech Connect

    Chrien, R.E.

    1986-01-01

    The object of this review is to survey observations of electromagnetic transitions in hypernuclei and to point out contributions of these observations to an understanding of the effective two-body hyperon-nucleon forces in the nucleus. The discussion concentrates on lambda-hyperon nucleon potentials. Future plans for high resolution hypernuclear spectroscopy using Ge diode detectors is discussed, especially regarding the window of utility of such devices. Expected improvements in beam facilities are also reviewed. 9 refs., 4 figs., 1 tab. (DWL)

  2. Transition Metal Switchable Mirror

    SciTech Connect

    2009-08-21

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  3. A translational evaluation of transitions.

    PubMed

    Jessel, Joshua; Hanley, Gregory P; Ghaemmaghami, Mahshid

    2016-06-01

    Transitions with nonhuman animals are typically framed as inescapable changes in signaled reinforcement schedules that result in a pause in responding unique to switches from rich to lean schedules. Pausing is considered to be a function of the aversive qualities of the contrasting reinforcement schedules. Transitions are typically framed in applied research as physical changes in location that evoke problem behavior maintained by the escape of an aversive event or resumption of a preferred event. We attempted to extend the basic framing of transitions to behaviors and contexts of social significance and evaluate a novel treatment for the problem of dawdling by 3 boys who had been diagnosed with autism spectrum disorder during rich-to-lean transitions. Dawdling during physical transitions was most readily observed when transitioning to lean contexts in Experiment 1. We then shortened transition duration in Experiment 2 by programming unsignaled and probabilistic rich reinforcement in the upcoming context. PMID:26916573

  4. Calculations with spectroscopic accuracy: energies, transition rates, and Landé gJ-factors in the carbon isoelectronic sequence from Ar XIII to Zn XXV

    NASA Astrophysics Data System (ADS)

    Ekman, J.; Jönsson, P.; Gustafsson, S.; Hartman, H.; Gaigalas, G.; Godefroid, M. R.; Froese Fischer, C.

    2014-04-01

    Extensive self-consistent multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and subsequent relativistic configuration interaction calculations are performed for 262 states belonging to the 15 configurations 2s22p2, 2s2p3, 2p4, 2s22p3l, 2s2p23l, 2p33l and 2s22p4l(l = 0,1,2) in selected carbon-like ions from Ar XIII to Zn XXV. Electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with existing theoretical calculations and data from the Chianti and NIST databases. In addition, Landé gJ-factors and radiative electric dipole transition rates are given for all ions. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines. Research supported in part by the Swedish Research council, Swedish Institute and by the IUAP-Belgian State Science Policy (BriX network P7/12).Tables of energy levels and transition rates (Tables 3-22) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A24

  5. Radiative rates for E1, E2, M1, and M2 transitions in F-like ions with 37 ≤ Z ≤ 53

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2016-05-01

    Calculations of energy levels, radiative rates and lifetimes are reported for 17 F-like ions with 37≤Z≤53. For brevity, results are only presented among the lowest 113 levels of the 2s22p5, 2s2p6, 2s22p43 ℓ, 2s2p53 ℓ, and 2p63 ℓ configurations, although the calculations have been performed for up to 501 levels in each ion. The general-purpose relativistic atomic structure package (GRASP) has been adopted for the calculations, and radiative rates (along with oscillator strengths and line strengths) are listed for all E1, E2, M1, and M2 transitions of the ions. Comparisons are made with earlier available experimental and theoretical energies, although these are limited to only a few levels for most ions. Therefore for additional accuracy assessments, particularly for energy levels, analogous calculations have been performed with the Flexible Atomic Code (FAC), for up to 72 259 levels. Limited previous results are available for radiative rates for comparison purposes, and no large discrepancy is observed for any transition and/or ion.

  6. Plasma inverse transition acceleration

    SciTech Connect

    Xie, Ming

    2001-06-18

    It can be proved fundamentally from the reciprocity theorem with which the electromagnetism is endowed that corresponding to each spontaneous process of radiation by a charged particle there is an inverse process which defines a unique acceleration mechanism, from Cherenkov radiation to inverse Cherenkov acceleration (ICA) [1], from Smith-Purcell radiation to inverse Smith-Purcell acceleration (ISPA) [2], and from undulator radiation to inverse undulator acceleration (IUA) [3]. There is no exception. Yet, for nearly 30 years after each of the aforementioned inverse processes has been clarified for laser acceleration, inverse transition acceleration (ITA), despite speculation [4], has remained the least understood, and above all, no practical implementation of ITA has been found, until now. Unlike all its counterparts in which phase synchronism is established one way or the other such that a particle can continuously gain energy from an acceleration wave, the ITA to be discussed here, termed plasma inverse transition acceleration (PITA), operates under fundamentally different principle. As a result, the discovery of PITA has been delayed for decades, waiting for a conceptual breakthrough in accelerator physics: the principle of alternating gradient acceleration [5, 6, 7, 8, 9, 10]. In fact, PITA was invented [7, 8] as one of several realizations of the new principle.

  7. Planet Demographics from Transits

    NASA Astrophysics Data System (ADS)

    Howard, Andrew

    2015-08-01

    From the demographics of planets detected by the Kepler mission, we have learned that there exists approximately one planet per star for planets larger than Earth orbiting inside of 1 AU. We have also learned the relative occurrence of these planets as a function of their orbital periods, sizes, and host star masses and metallicities. In this talk I will review the key statistical findings that the planet size distribution peaks in the range 1-3 times Earth-size, the orbital period distribution is characterized by a power-law cut off at short periods, small planets are more prevalent around small stars, and that approximately 20% of Sun-like stars hosts a planet 1-2 times Earth-size in a habitable zone. Looking forward, I will describe analysis of photometry from the K2 mission that is yielding initial planet discoveries and offering the opportunity to measure planet occurrence in widely separated regions of the galaxy. Finally, I will also discuss recent techniques to discover transiting planets in space-based photometry and to infer planet population properties from the ensemble of detected and non-detected transit signals.

  8. Transitions in viscous withdrawal

    NASA Astrophysics Data System (ADS)

    Zhang, Wendy W.

    2008-11-01

    A process analogous to flow-focusing occurs in extended and stably stratified layers of immiscible, viscous liquids. In viscous withdrawal, an axisymmetric converging flow is imposed in the upper layer. When the upper layer flow is weak, the interface forms a hump. No liquid from the lower layer is entrained. When the upper layer flow is strong, liquid from the lower layer is entrained and the interface becomes a spout. Here I summarize recent results on the fundamental mechanisms controlling these regimes. For selective withdrawal, a clear picture has emerged, with good agreement between theory, simulation and experiment. The regime ends when the viscous stress exerted by the upper layer flow overcomes surface tension, creating a saddle-node bifurcation in the hump solution. Less is understood about viscous entrainment. A long-wavelength model including only local information is degenerate, possessing many solutions for the same withdrawal condition. Including information about the global geometry removes this degeneracy but also makes the surprising prediction that global geometry can change the nature of the transition. First-order, weakly first-order or continuous transitions are all possible. How these results relate to the variety of experimental phenomena, such as stable, micron-sized spouts, intricate patterns of hysteresis and multiple stable spout states under the same condition, is at present unclear. (Includes material from joint works with Blanchette, Cohen, Kleine Berkenbusch, and Schmidt.)

  9. 309 Building transition plan

    SciTech Connect

    Graves, C.E.

    1994-08-31

    The preparation for decontamination and decommissioning (transition) of the 309 Building is projected to be completed by the end of the fiscal year (FY) 1998. The major stabilization and decontamination efforts include the Plutonium Recycle Test Reactor (PRTR), fuel storage and transfer pits, Transfer Waste (TW) tanks and the Ion Exchange Vaults. In addition to stabilizing contaminated areas, equipment, components, records, waste products, etc., will be dispositioned. All nonessential systems, i.e., heating, ventilation, and air conditioning (HVAC), electrical, monitoring, fluids, etc., will be shut down and drained/de-energized. This will allow securing of the process, laboratory, and office areas of the facility. After that, the facility will be operated at a level commensurate with its surveillance needs while awaiting D&D. The implementation costs for FY 1995 through FY 1998 for the transition activities are estimated to be $1,070K, $2,115K, $2,939K, and $4,762K, respectively. Costs include an assumed company overhead of 20% and a 30% out year contingency.

  10. Partnership Transitions and Maternal Parenting

    PubMed Central

    Beck, Audrey N.; Cooper, Carey E.; McLanahan, Sara; Brooks-Gunn, Jeanne

    2011-01-01

    We use data from the Fragile Families and Child Wellbeing Study (N = 1,975) to examine the association between mothers’ partnership changes and parenting behavior during the first five years of their children’s lives. We compare coresidential with dating transitions, and recent with more distal transitions. We also examine interactions between transitions and race/ethnicity, maternal education and family structure at birth. Findings indicate that both coresidential and dating transitions were associated with higher levels of maternal stress and harsh parenting; recent transitions had stronger associations than distal transitions. Maternal education significantly moderates these associations, with less educated mothers responding more negatively to instability in terms of maternal stress, and more educated mothers responding more negatively in terms of literacy activities. PMID:21423848

  11. Phases and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Gitterman, Moshe

    2014-09-01

    In discussing phase transitions, the first thing that we have to do is to define a phase. This is a concept from thermodynamics and statistical mechanics, where a phase is defined as a homogeneous system. As a simple example, let us consider instant coffee. This consists of coffee powder dissolved in water, and after stirring it we have a homogeneous mixture, i.e., a single phase. If we add to a cup of coffee a spoonful of sugar and stir it well, we still have a single phase -- sweet coffee. However, if we add ten spoonfuls of sugar, then the contents of the cup will no longer be homogeneous, but rather a mixture of two homogeneous systems or phases, sweet liquid coffee on top and coffee-flavored wet sugar at the bottom...

  12. Nonadiabatic transition path sampling

    NASA Astrophysics Data System (ADS)

    Sherman, M. C.; Corcelli, S. A.

    2016-07-01

    Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.

  13. Hybrid Electric Transit Bus

    NASA Technical Reports Server (NTRS)

    Viterna, Larry A.

    1997-01-01

    A government, industry, and university cooperative is developing an advanced hybrid electric city transit bus. Goals of this effort include doubling the fuel economy compared to current buses and reducing emissions to one-tenth of current EPA standards. Unique aspects of the vehicle's power system include the use of ultra-capacitors as an energy storage system, and a planned natural gas fueled turbogenerator developed from a small jet engine. Power from both the generator and energy storage system is provided to a variable speed electric motor attached to the rear axle. At over 15000 kg gross weight, this is the largest vehicle of its kind ever built using ultra-capacitor energy storage. This paper describes the overall power system architecture, the evolution of the control strategy, and its performance over industry standard drive cycles.

  14. Maritime in transit care.

    PubMed

    Bott, G; Barnard, J; Prior, K

    2015-01-01

    Operation GRITROCK saw the first operational deployment of the Maritime In Transit Care team from the Role 2 (Enhanced) (R2(E)) Medical Treatment Facility, which is able to provide Damage Control Surgery and the limited holding of patients, situated on board RFA ARGUS. Whilst the Medical Emergency Response Team demonstrated the capability of advanced military Pre-Hospital Emergency Care (PHEC) on Op HERRICK, the need to provide a similar high level of care on contingency operations was recognised. Op GRITROCK allowed for the continued exploration of a maritime capability from an established R2(E) platform whilst providing medical evacuation capability for a significant population at risk distributed over a large Joint Operation Area. Although the patient load during the operation was low, key lessons were learnt and opportunities identified to further develop the newly recognised sub-speciality of PHEC, both medically and logistically, and these will be discussed in this article. PMID:26867404

  15. Probiotics in transition.

    PubMed

    Shanahan, Fergus; Dinan, Timothy G; Ross, Paul; Hill, Colin

    2012-11-01

    Despite the hyperbole often linked with a popular research field, the scientific rationale for probiotics is sound. The probiotic concept is not new but is undergoing transition as knowledge of the gut microbiota in health and disease becomes translated to the clinic. Operationally, a probiotic represents a mimic of and/or supplement to the normal gut microbiota. Much confusion has arisen among consumers because of media misportrayals of probiotics as all being the same. However, with clarification of the molecular basis of host-microbe interactions, the selection criteria for probiotics and the delineation of their distinct mechanisms of action are improving. Most probiotics are from the genus Lactobacillus or Bifidobacterium; this is likely to change and diversify. Similarly, the development of new therapeutic strategies, such as the development of phagebiotics, psychobiotics, and genetically modified pharmabiotics, is poised to become a therapeutic reality. PMID:23010563

  16. Nonadiabatic transition path sampling.

    PubMed

    Sherman, M C; Corcelli, S A

    2016-07-21

    Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase. PMID:27448877

  17. Aspects of Transition in Turbomachines

    NASA Technical Reports Server (NTRS)

    Hodson, H. P.

    2007-01-01

    This talk provides a description of several types of transition encountered in turbomachines. It is based largely on personal experience of the detection of transition in turbomachines. Examples are taken from axial compressors, axial turbines and radial turbines. The illustrations are concerned with transition in steady and unsteady boundary layers that develop under the influence of two-dimensional and three-dimensional flow fields.

  18. Evaluation of variation in ( m_p/m_e) from the frequency difference between the 15N2+ and 87Sr transitions

    NASA Astrophysics Data System (ADS)

    Kajita, Masatoshi

    2016-07-01

    The uncertainty of the 87Sr1 S0-3 P0 transition frequency (429 THz) has been reduced to the level of 10^{-18}. Also, the 15N2+ Q(0) vibrational transition frequency is expected to be measured with an uncertainty of 10^{-17} , and the v = 0-7 transition frequency (422 THz) is close to the 87Sr transition frequency. In this paper, we propose a test for the variation in the proton-to-electron mass ratio μ via precise measurement of the difference (f_d=7 THz) between these transition frequencies. By measuring f_d within the uncertainty of 10^{-16}, a variation in μ of 4 × 10^{-18} can be detected. The 15N2+ v =0 -7 Q(0) transition frequency is free from Zeeman and electric quadrupole shifts. The dc Stark coefficient is about 0.2 mHz/(V/cm)2, and the measurement of f_d with an uncertainty lower than 10^{-16} appears to be attainable using molecular ions in a string crystal. The 15N2+ transition frequency is observed via the two-photon excitation of a laser with a wavelength of 1422 nm (laser A). Another laser with a wavelength of 1396 nm (laser B) is used as a 87Sr clock laser after frequency doubling. The frequency difference between lasers A and B (3.5 THz) should be measured using a frequency comb. Lasers A and B can be transferred to another laboratory via an optical fiber. Therefore, a sensitive test of the variation in μ can be performed in cooperation between two distant laboratories.

  19. Electronic transitions of scandium monophosphide

    NASA Astrophysics Data System (ADS)

    Wang, Na; Ng, K. F.; Cheung, A. S.-C.

    2015-08-01

    The electronic transition spectrum of scandium monophosphide (ScP) molecule in the visible region between 480 and 575 nm has been recorded using laser ablation/reaction free jet expansion and laser-induced fluorescence spectroscopy. Nine vibrational bands belonging to two electronic transition systems, namely the [19.0]1Σ+ - X1Σ+ transition, and [19.8]3Σ+ - a3Σ+ transition, have been identified and rotationally analysed. A least squares fit of the measured lines yielded molecular constants for the singlet and the triplet electronic states. Theoretical calculation results have been used to assist the assignment of the observed electronic states.

  20. Primordial equation of state transitions

    NASA Astrophysics Data System (ADS)

    Aravind, Aditya; Lorshbough, Dustin; Paban, Sonia

    2016-06-01

    We revisit the physics of transitions from a general equation of state parameter to the final stage of slow-roll inflation. We show that it is unlikely for the modes comprising the cosmic microwave background to contain imprints from a preinflationary equation of state transition and still be consistent with observations. We accomplish this by considering observational consistency bounds on the amplitude of excitations resulting from such a transition. As a result, the physics which initially led to inflation likely cannot be probed with observations of the cosmic microwave background. Furthermore, we show that it is unlikely that equation of state transitions may explain the observed low multipole power suppression anomaly.

  1. Quantum phase transition in space

    SciTech Connect

    Damski, Bogdan; Zurek, Wojciech H

    2008-01-01

    A quantum phase transition between the symmetric (polar) phase and the phase with broken symmetry can be induced in a ferromagnetic spin-1 Bose-Einstein condensate in space (rather than in time). We consider such a phase transition and show that the transition region in the vicinity of the critical point exhibits scalings that reflect a compromise between the rate at which the transition is imposed (i.e., the gradient of the control parameter) and the scaling of the divergent healing length in the critical region. Our results suggest a method for the direct measurement of the scaling exponent {nu}.

  2. SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF C-LIKE IONS WITH Z = 13-36

    SciTech Connect

    Wang, K.; Li, D. F.; Liu, H. T.; Han, X. Y.; Duan, B.; Li, C. Y.; Li, J. G.; Yan, J.; Guo, X. L.; Chen, C. Y.

    2015-01-01

    Based on systematic calculations using a combined relativistic configuration interaction and a many-body perturbation theory (MBPT) approach, we provide a complete and consistent data set for 46 levels belonging to the 2s {sup 2}2p {sup 2}, 2s2p {sup 3}, 2p {sup 4}, 2s {sup 2}2p3s, 2s {sup 2}2p3p, and 2s {sup 2}2p3d configurations in C-like ions with 13 ≤ Z ≤ 36. The data set includes energy levels as well as electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transition properties. Extensive comparisons with available observed and calculated results are made and indicate that the present MBPT calculations are highly accurate. The present data set can be used reliably for many purposes, such as the line identification of observed spectra, and modeling and diagnostics of astrophysical and fusion plasmas.

  3. Anomalous pressure dependence of the superconducting transition temperature in TlNi2Se2 -xSx

    NASA Astrophysics Data System (ADS)

    Goh, S. K.; Chang, H. C.; Reiss, P.; Alireza, P. L.; Cheung, Y. W.; Lau, S. Y.; Wang, Hangdong; Mao, Qianhui; Yang, Jinhu; Fang, Minghu; Grosche, F. M.; Sutherland, M. L.

    2014-11-01

    We report the pressure dependence of the superconducting transition temperature Tc in TlNi2Se2 -xSx detected via the ac susceptibility method. The pressure-temperature phase diagram constructed for TlNi2Se2 , TlNi2S2 , and TlNi2SeS exhibits two unexpected features: (a) a sudden collapse of the superconducting state at moderate pressure for all three compositions and (b) a dome-shaped pressure dependence of Tc for TlNi2SeS . These results point to the nontrivial role of S substitution and its subtle interplay with applied pressure, as well as interesting superconducting properties of the TlNi2Se2 -xSx system.

  4. Connecticut Transit (CTTRANSIT) Fuel Cell Transit Bus: Preliminary Evaluation Results

    SciTech Connect

    Chandler, K.; Eudy, L.

    2008-10-01

    This report provides preliminary results from a National Renewable Energy Laboratory evaluation of a protoptye fuel cell transit bus operating at Connecticut Transit in Hartford. Included are descriptions of the planned fuel cell bus demonstration and equipment; early results and agency experience are also provided.

  5. Transition Assessment: Using Gap Analysis to Enhance Effective Transition Planning

    ERIC Educational Resources Information Center

    Lowenthal, Alison B.; Bassett, Diane S.

    2012-01-01

    Over the past decade, there has been an increased emphasis on transition planning for students with exceptional needs. This is in part the result of the mandates contained in the Individuals with Disabilities Education Improvement Act of 2004. This increased emphasis has revealed a number of shortcomings with how transition planning is done…

  6. Phase transitions in disordered systems

    NASA Astrophysics Data System (ADS)

    Hrahsheh, Fawaz Y.

    Disorder can have a wide variety of consequences for the physics of phase transitions. Some transitions remain unchanged in the presence of disorder while others are completely destroyed. In this thesis we study the effects of disorder on several classical and quantum phase transitions in condensed matter systems. After a brief introduction, we study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte-Carlo simulations. Our results provide numerical evidence for the exotic infinite-randomness scenario. We study classical and quantum smeared phase transitions in substitutional alloys A1-xBx. Our results show that the disorder completely destroys the phase transition with a pronounced tail of the ordered phase developing for all compositions x < 1. In addition, we find that short-ranged disorder correlations can have a dramatic effect on the transition. Moreover, we show an experimental realization of the composition-tuned ferromagnetic-to-paramagnetic quantum phase transition in Sr1-xCa xRuO3. We investigate the effects of disorder on first-order quantum phase transitions on the example of the N-color quantum Ashkin-Teller model. By means of a strong disorder renormalization group, we demonstrate that disorder rounds the first-order transition to a continuous one for both weak and strong coupling between the colors. Finally, we investigate the superfluid-insulator quantum phase transition of one-dimensional bosons with off-diagonal disorder by means of large-scale Monte-Carlo simulations. Beyond a critical disorder strength, we find nonuniversal, disorder dependent critical behavior.

  7. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  8. Adult Transition Program without Walls

    ERIC Educational Resources Information Center

    Moberg, Eric

    2010-01-01

    Best practices in adult transition special education for moderate to severe students suggest student-centered planning that maximizes independence in adult life. Based on the above sources, school districts and governing boards would best serve moderate to severe transition special education students with increasing integration into the community…

  9. ESTIMATION OF AGE TRANSITION PROBABILITIES.

    ERIC Educational Resources Information Center

    ZINTER, JUDITH R.

    THIS NOTE DESCRIBES THE PROCEDURES USED IN DETERMINING DYNAMOD II AGE TRANSITION MATRICES. A SEPARATE MATRIX FOR EACH SEX-RACE GROUP IS DEVELOPED. THESE MATRICES WILL BE USED AS AN AID IN ESTIMATING THE TRANSITION PROBABILITIES IN THE LARGER DYNAMOD II MATRIX RELATING AGE TO OCCUPATIONAL CATEGORIES. THREE STEPS WERE USED IN THE PROCEDURE--(1)…

  10. Phase Transitions for Suspension Flows

    NASA Astrophysics Data System (ADS)

    Iommi, Godofredo; Jordan, Thomas

    2013-06-01

    This paper is devoted to studying the thermodynamic formalism for suspension flows defined over countable alphabets. We are mostly interested in the regularity properties of the pressure function. We establish conditions for the pressure function to be real analytic or to exhibit a phase transition. We also construct an example of a potential for which the pressure has countably many phase transitions.

  11. Transition Programs: Bridging the Gap.

    ERIC Educational Resources Information Center

    Peavey, Kay

    This document shares the collective wisdom and experience of professionals who have successfully guided the transition of hundreds of youths and adults from New York's correctional institutions back into the community. The first section begins with an overview of the New York State Education Department's transition program model to move…

  12. Partnership Transitions and Maternal Parenting

    ERIC Educational Resources Information Center

    Beck, Audrey N.; Cooper, Carey E.; McLanahan, Sara; Brooks-Gunn, Jeanne

    2010-01-01

    We use data from the Fragile Families and Child Wellbeing Study (N = 1,975) to examine the association between mothers' partnership changes and parenting behavior during the first 5 years of their children's lives. We compare coresidential with dating transitions and recent with more distal transitions. We also examine interactions between…

  13. Transition Planning for Foster Youth

    ERIC Educational Resources Information Center

    Geenen, Sarah J.; Powers, Laurie E.

    2006-01-01

    The study evaluated the IEPs/Individualized Transition Plans of 45 students who were in special education and foster care, and compared them to the plans of 45 students who were in special education only. Results indicate that the transition plans of foster youth with disabilities were poor in quality, both in absolute terms and in comparison to…

  14. Developmental Transitions in Male Sexuality.

    ERIC Educational Resources Information Center

    Lewis, Robert; And Others

    1978-01-01

    The article defines and elaborates on eight transitions in male sexuality, the first being the gender identity transition, and the last being the male climacteric. It discusses society's lack of support. Originally presented at the American Sociological Association Session on the Male Role in Society, New York City, 1976. (LPG)

  15. Nonadiabatic transitions and gauge structure

    SciTech Connect

    Nakamura, K. ); Rice, S.A. )

    1994-04-01

    We examine the role of fictitious gauge structure in nonadiabatic transitions for transport in open paths. Local features of the gauge potential modify the nature of the intersection of the adiabatic energy surfaces and thereby affect crucially the Landau-Zener formula for a single-passage transition rate.

  16. Rural Transition Strategies That Work.

    ERIC Educational Resources Information Center

    Schwartz, Phebe

    Successful rural transition strategies which assist disabled rural secondary students in the transition from school to employment and community integration are described. Effective programs and specific strategies touch on such topic areas as job/career exploration, on-site job exploration, career planning, prevocational training, transition…

  17. Sampling diffusive transition paths

    SciTech Connect

    F. Miller III, Thomas; Predescu, Cristian

    2006-10-12

    We address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with sampling infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with sampling the coarse features of long paths. The fine-features sampling stiffness is eliminated with the use of the fast sampling algorithm (FSA), and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. We use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature.

  18. Sampling diffusive transition paths.

    PubMed

    Miller, Thomas F; Predescu, Cristian

    2007-04-14

    The authors address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with the sampling of infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with the sampling of the coarse features of long paths. The fine-feature sampling stiffness is eliminated with the use of the fast sampling algorithm, and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. The authors use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature. PMID:17444696

  19. Theory of antiferroelectric phase transitions

    NASA Astrophysics Data System (ADS)

    Tolédano, Pierre; Guennou, Mael

    2016-07-01

    At variance with structural ferroic phase transitions which give rise to macroscopic tensors coupled to macroscopic fields, criteria defining antiferroelectric (AFE) phase transitions are still under discussion due to the absence of specific symmetry properties characterizing their existence. They are recognized by the proximity of a ferroelectric (FE) phase induced under applied electric field, with a double hysteresis loop relating the induced polarization to the electric field and a typical anomaly of the dielectric permittivity. Here, we show that there exist indeed symmetry criteria defining AFE transitions. They relate the local symmetry of the polar crystallographic sites emerging at an AFE phase transition with the macroscopic symmetry of the AFE phase. The dielectric properties of AFE transitions are deduced from a Landau theoretical model in which ferroelectric and ferrielectric phases are shown to stabilize as the result of specific symmetry-allowed couplings of the AFE order parameter with the field-induced polarization.

  20. Gel transitions in colloidal suspensions

    NASA Astrophysics Data System (ADS)

    Bergenholtz, J.; Fuchs, M.

    1999-12-01

    The idealized mode-coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures, MCT predicts a slowing down of the local dynamics and ergodicity-breaking transitions. The non-ergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the non-ergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical non-ergodicity parameters; this is motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low-temperature MCT non-ergodicity transitions.

  1. Assessing transitional phenomena with the transitional object memory probe.

    PubMed

    Fowler, C; Hilsenroth, M J; Handler, L

    1998-01-01

    Winnicott's concept of transitional relatedness has captured the interest of psychoanalysts because it provides an understanding of the dialectical process occurring between inner and outer reality, and by extension, between analyst and analysand. Clinical observations related to transitional phenomena have led the authors to develop a projective early memory probe that assesses transitional phenomena. The transitional object early memory probe was tested both for its empirical validity and for its clinical utility in psychodynamic psychotherapy. Construct validity was assessed by comparing memory scores to the Rorschach Transitional Object Scale, as well as to therapist ratings of patient behaviors. Results demonstrated moderate correlations between early memory scores and Rorschach scale scores. Equally important was the finding that early memory scores were significantly correlated with therapist ratings of key behavioral patterns in therapy. A case vignette highlights the clinical application of the transitional object probe in assessing the capacity for transitional relatedness. In this case, the data gleaned from the patient's memories provided the therapist with a sharper focus on their role in the patient's growing capacity for more vital and creative contact with reality. PMID:9810109

  2. Selenophene transition metal complexes

    SciTech Connect

    White, C.J.

    1994-07-27

    This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the {eta}{sup 5}- and the {eta}{sup 1}(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The {sup 77}Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of {eta}{sup 1}(S)-bound thiophenes, {eta}{sup 1}(S)-benzothiophene and {eta}{sup 1}(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the {eta}{sup 1}(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh{sub 3})Re(2-benzothioenylcarbene)]O{sub 3}SCF{sub 3} was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the {eta}{sup 1}(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

  3. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  4. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  5. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  6. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  7. 22 CFR 41.71 - Transit aliens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Transit aliens. 41.71 Section 41.71 Foreign... NATIONALITY ACT, AS AMENDED Transit Aliens § 41.71 Transit aliens. (a) Transit aliens—general. An alien is classifiable as a nonimmigrant transit alien under INA 101(a) (15) (C) if the consular officer is...

  8. 20 CFR 627.901 - Transition period.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Transition period. 627.901 Section 627.901... PROGRAMS UNDER TITLES I, II, AND III OF THE ACT Transition Provisions § 627.901 Transition period. The transition period ended June 30, 1993 unless otherwise stated. The intent of the transition period is...

  9. Major evolutionary transitions in individuality

    PubMed Central

    West, Stuart A.; Fisher, Roberta M.; Gardner, Andy; Kiers, E. Toby

    2015-01-01

    The evolution of life on earth has been driven by a small number of major evolutionary transitions. These transitions have been characterized by individuals that could previously replicate independently, cooperating to form a new, more complex life form. For example, archaea and eubacteria formed eukaryotic cells, and cells formed multicellular organisms. However, not all cooperative groups are en route to major transitions. How can we explain why major evolutionary transitions have or haven’t taken place on different branches of the tree of life? We break down major transitions into two steps: the formation of a cooperative group and the transformation of that group into an integrated entity. We show how these steps require cooperation, division of labor, communication, mutual dependence, and negligible within-group conflict. We find that certain ecological conditions and the ways in which groups form have played recurrent roles in driving multiple transitions. In contrast, we find that other factors have played relatively minor roles at many key points, such as within-group kin discrimination and mechanisms to actively repress competition. More generally, by identifying the small number of factors that have driven major transitions, we provide a simpler and more unified description of how life on earth has evolved. PMID:25964342

  10. The Visibility of Earth Transits

    NASA Technical Reports Server (NTRS)

    Castellano, Timothy P.; Doyle, Laurance; McIntosh, Dawn; DeVincenzi, Donald (Technical Monitor)

    2000-01-01

    The recent photometric detection of planetary transits of the solar-like star HD 209458 at a distance of 47 parsecs suggest that transits can reveal the presence of Jupiter-size planetary companions in the solar neighborhood. Recent space-based transit searches have achieved photometric precision within an order of magnitude of that required to detect the much smaller transit signal of an earth-size planet across a solar-size star. Laboratory experiments in the presence of realistic noise sources have shown that CCDs can achieve photometric precision adequate to detect the 9.6 E-5 dimming of the Sun due to a transit of the Earth. Space-based solar irradiance monitoring has shown that the intrinsic variability of the Sun would not preclude such a detection. Transits of the Sun by the Earth would be detectable by observers that reside within a narrow band of sky positions near the ecliptic plane, if the observers possess current Earth epoch levels of technology and astronomical expertise. A catalog of solar-like stars that satisfy the geometric condition for Earth transit visibility are presented.

  11. The Visibility of Earth Transits

    NASA Technical Reports Server (NTRS)

    Castellano, Tim; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The recent detection of planetary transits of the solar-like star HD 209458 at a distance of 47 parsecs suggest that transits can reveal the presence of Jupiter-size planetary companions in the solar neighborhood. Recent space-based transit searches have achieved photometric precision within an order of magnitude of that required to detect the much smaller transit signal of an earth-size planet around a solar-size star. Laboratory experiments in the presence of realistic noise sources have shown that CCDs can achieve photometric precision adequate to detect the 9.6 E-5 dimming, of the Sun due to a transit of the Earth. Space-based solar irradiance monitoring has shown that the intrinsic variability of the Sun would not preclude such a detection. Transits of the Sun by the Earth would be detectable by observers that reside within a narrow band of sky positions near the ecliptic plane, if the observers possess current Earth epoch levels of technology and astronomical expertise. A catalog of candidate target stars, their properties, and simulations of the photometric Earth transit signal detectability at each target is presented.

  12. Electronic Transitions of Yttrium Monophosphide

    NASA Astrophysics Data System (ADS)

    Cheung, Allan S. C.; Li, Biu Wa; Chan, MAN-CHOR

    2015-06-01

    Electronic transition spectrum of the yttrium monophosphide (YP) molecule in the visible region between 715 nm and 880 nm has been recorded using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The YP molecule was produced by reacting laser - ablated yttrium atoms with PH3 seeded in argon. Thirteen vibrational bands were analyzed and five electronic transition systems have identified, namely the [12.2] Ω = 3 - X3 Π_2 transition, [13.3] Ω = 3 - X3 Π_2 transition, [13.4] Ω = 3 - X3 Π_2 transition, [13.5] Ω = 3 - X3 Π_2 transition, and [13.4] Ω = 2 - X3 Π_2 transition. Least squares fits of the measured rotational lines yielded molecular constants for the ground and excited states. The ground state symmetry and the bond length r_0 of the YP molecule have been determined to be a X3 Π_2 state and 2.4413 Å respectively in this work. A molecular orbital energy level diagram has been used to help the assignment of the observed electronic states. This work represents the first experimental investigation of the spectrum of the YP molecule.

  13. Major evolutionary transitions in individuality.

    PubMed

    West, Stuart A; Fisher, Roberta M; Gardner, Andy; Kiers, E Toby

    2015-08-18

    The evolution of life on earth has been driven by a small number of major evolutionary transitions. These transitions have been characterized by individuals that could previously replicate independently, cooperating to form a new, more complex life form. For example, archaea and eubacteria formed eukaryotic cells, and cells formed multicellular organisms. However, not all cooperative groups are en route to major transitions. How can we explain why major evolutionary transitions have or haven't taken place on different branches of the tree of life? We break down major transitions into two steps: the formation of a cooperative group and the transformation of that group into an integrated entity. We show how these steps require cooperation, division of labor, communication, mutual dependence, and negligible within-group conflict. We find that certain ecological conditions and the ways in which groups form have played recurrent roles in driving multiple transitions. In contrast, we find that other factors have played relatively minor roles at many key points, such as within-group kin discrimination and mechanisms to actively repress competition. More generally, by identifying the small number of factors that have driven major transitions, we provide a simpler and more unified description of how life on earth has evolved. PMID:25964342

  14. Magnetic TRAnsition Region Probe (MTRAP)

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Davis, John; Hathaway, David; Six, N. Frank (Technical Monitor)

    2002-01-01

    MTRAP (Magnetic Transition Region Probe) will reveal the fine-scale physical processes in the Sun's magnetic transition region, the complex layer from the upper photosphere to the upper chromosphere/lower transition region. In the magnetic transition region plasma forces and magnetic forces are of comparable strength, which results in complex interplay of the two, which interplay governs the coupling of the convectively-driven deeper layers to the magnetically-driven upper transition region and inner corona. The fine-scale magnetic structure, processes, and events in the magnetic transition region are key to the genesis of the Sun's entire hot, dynamic outer atmosphere and to the initiation of large eruptive events. MTRAP will be a single spacecraft in Sun-synchronous Earth orbit. Because MTRAP will probe and measure the 3-D structure and dynamics of the magnetic field and plasma in the chromosphere and transition region with unprecedented resolution, the required telescope size and telemetry rates dictate that MTRAP be in Earth orbit, not in deep space. The observations will feature visible and infrared maps of vector magnetic and velocity fields in the magnetic transition region and photosphere. These will have large field of view (greater than 100,000 km), high resolution (greater than 100 km), and high sensitivity (greater than 30 G in transverse field). These observations of the lower atmosphere will be complemented by UV maps of the structure, velocity, and magnetic field (including the full vector field if technically feasible) higher up, in the upper chromosphere and lower transition region. MTRAP will also have an EUV imaging spectrograph observing coronal structure and dynamics in the same field of view with comparable resolution. Specific phenomena to be analyzed include spicules, bright points, jets, the base of plumes, and the triggering of eruptive flares and coronal mass ejections. Additional information is included in the original extended abstract.

  15. Accurate Cross Sections for Excitation of Resonance Transitions in Atomic Oxygen

    NASA Technical Reports Server (NTRS)

    Tayal, S. S.

    2004-01-01

    Electron collision excitation cross sections for the resonance 2p(sup)4 (sup 3)P-2p(sup 3)3s (sup 3)S(sup 0), 2p(sup 4) (sup 3)P-2p(sup 3)3d (sup 3)D(sup 0), 2p4 (sup 3)P-2p(sup 3)3s (sup 3)D(sup 0), 2p(sup 4) (sup 3)P-2p(sup 3)3s (sup 3)P(sup 0) and 2p(sup 4) (sup 3)P-2s2p(sup 5) (sup 3)P(sup 0) transitions have been calculated by using the R matrix with a pseudostates approach for incident electron energies from near threshold to 100 eV. The excitation of these transition sgives rise to strong atomic oxygen emission features at 1304, 1027, 989, 878, and 792 Angstrom in the spectra of several planetary atmospheres. We included 22 spectroscopic bound and autoionizing states and 30 pseudostates in the close-coupling expansion. The target wave functions are chosen to properly account for the important correlation and relaxation effects. The effect of coupling to the continuum is included through the use of pseudostates. The contribution of the ionization continuum is significant for resonance transitions. Measured absolute direct excitation cross sections of 0 I are reported by experimental groups from the Jet Propulsion Laboratory and Johns Hopkins University. Good agreement is noted for the 2p(sup)4 (sup 3)P-2p(sup 3)3s (sup 3)S(sup 0) transition (lambda 1304 Ang) with measured cross sections from both groups that agree well with each other. There is disagreement between experiments for other transitions. Our results support the measured cross sections from the Johns Hopkins University for the 2p(sup 4) (sup 3)P-2p(sup 3)3d (sup 3)D(sup 0) and 2p4 (sup 3)P-2p(sup 3)3s (sup 3)D(sup 0) transitions, while for the 2p4 (sup 3)P-2p(sup 3)3s (sup 3)D(sup 0) transition the agreement is switched to the measured cross sections from the Jet Propulsion Laboratory.

  16. Fluctuation driven electroweak phase transition

    NASA Technical Reports Server (NTRS)

    Gleiser, Marcelo; Kolb, Edward W.

    1991-01-01

    We examine the dynamics of the electroweak phase transition in the early Universe. For Higgs masses in the range 46 less than or = M sub H less than or = 150 GeV and top quark masses less than 200 GeV, regions of symmetric and asymmetric vacuum coexist to below the critical temperature, with thermal equilibrium between the two phases maintained by fluctuations of both phases. We propose that the transition to the asymmetric vacuum is completed by percolation of these subcritical fluctuations. Our results are relevant to scenarios of baryogenesis that invoke a weakly first-order phase transition at the electroweak scale.

  17. Linear-time transitive orientation

    SciTech Connect

    McConnell, R.M.; Spinrad, J.P.

    1997-06-01

    The transitive orientation problem is the problem of assigning a direction to each edge of a graph so that the resulting digraph is transitive. A graph is a comparability graph if such an assignment is possible. We describe an O(n + m) algorithm for the transitive orientation problem, where n and m are the number of vertices and edges of the graph; full details are given in. This gives linear time bounds for maximum clique and minimum vertex coloring on comparability graphs, recognition of two-dimensional partial orders, permutation graphs, cointerval graphs, and triangulated comparability graphs, and other combinatorial problems on comparability graphs and their complements.

  18. Holographic approach to phase transitions

    SciTech Connect

    Franco, Sebastian; Garcia-Garcia, Antonio M.; Rodriguez-Gomez, Diego

    2010-02-15

    We provide a description of phase transitions at finite temperature in strongly coupled field theories using holography. For this purpose, we introduce a general class of gravity duals to superconducting theories that exhibit various types of phase transitions (first or second order with both mean and non-mean field behavior) as parameters in their Lagrangian are changed. Moreover the size and strength of the conductivity coherence peak can also be controlled. Our results suggest that certain parameters in the gravitational dual control the interactions responsible for binding the condensate and the magnitude of its fluctuations close to the transition.

  19. Nonradiative transition dynamics in alexandrite

    NASA Technical Reports Server (NTRS)

    Gayen, S. K.; Wang, W. B.; Petricevic, V.; Alfano, R. R.

    1986-01-01

    The first direct picosecond time-resolved measurement of the nonradiative transition dynamics between the excited 4T2 pump band and the metastable 2E storage level of the trivalent chromium ion in alexandrite is reported. The nonradiative relaxation times of 17 ps for intra-4T2 vibrational transitions, and 27 ps for 4T2-2E electronic transition are obtained. The thermal repopulation rate of the 4T2 state from the metastable 2E level is of the order 3.5 x 10 to the 9th per s.

  20. Next Generation Transit Survey (NGTS)

    NASA Astrophysics Data System (ADS)

    Wheatley, Peter J.; Pollacco, Don L.; Queloz, Didier; Rauer, Heike; Watson, Christopher A.; West, Richard G.; Chazelas, Bruno; Louden, Tom M.; Bannister, Nigel; Bento, Joao; Burleigh, Matthew; Cabrera, Juan; Eigmüller, Philipp; Erikson, Anders; Genolet, Ludovic; Goad, Michael; Grange, Andrew; Jordán, Andrés; Lawrie, Katherine; McCormac, James; Neveu, Marion; Walker, Simon

    2014-01-01

    The Next Generation Transit Survey (NGTS) is a new ground-based survey for transiting exoplanets. Our primary goal is to find the first statistically-significant sample of Neptunes and super-Earths that are bright enough for radial velocity confirmation. By measuring precise masses and radii we will constrain the bulk composition and internal structure of planets that span the transition between the gas giants and terrestrial planets. Our brightest exoplanets will also be suitable for atmospheric characterisation with large facilities such as the VLT, JWST and the E-ELT. NGTS construction began in June 2013, and the survey is due to commence in 2014.

  1. Transition to turbulence in pipe flow as a phase transition

    NASA Astrophysics Data System (ADS)

    Vasudevan, Mukund; Hof, Björn

    2015-11-01

    In pipe flow, turbulence first arises in the form of localized turbulent patches called puffs. The flow undergoes a transition to sustained turbulence via spatio-temporal intermittency, with puffs splitting, decaying and merging in the background laminar flow. However, the due to mean advection of the puffs and the long timescales involved (~107 advective time units), it is not possible to study the transition in typical laboratory set-ups. So far, it has only been possible to indirectly estimate the critical point for the transition. Here, we exploit the stochastic memoryless nature of the puff decay and splitting processes to construct a pipe flow set-up, that is periodic in a statistical sense. It then becomes possible to study the flow for sufficiently long times and characterize the transition in detail. We present measurements of the turbulent fraction as a function of Reynolds number which in turn allows a direct estimate of the critical point. We present evidence that the transition has features of a phase transition of second order.

  2. VizieR Online Data Catalog: SiIX K-shell energy levels and transitions (Wei+, 2014)

    NASA Astrophysics Data System (ADS)

    Wei, H. G.; Shi, J. R.; Wang, F. L.; Zhong, J. Y.; Liang, G. Y.; Zhao, G.

    2014-05-01

    Accurate atomic data are needed to analyze the SiIX K-shell features in astrophysical X-ray spectra. Relative large discrepancies in the existing atomic data have impeded this progress. We present the accurate SiIX K-shell transition data, including K-shell energy levels, wavelengths, radiative rates, and oscillator strengths. The flexible atomic code (FAC), which is a fully relativistic atomic code with configuration interaction (CI) included, was employed to calculate these data. To investigate the CI effects, calculations with different configurations included were carried out. The K-shell atomic data of SiIX transitions between 1s22s22p2, 1s22s2p3, 1s22p4, 1s2s22p3, 1s2s2p4, and 1s2p5 are reported. The accuracy of our data is demonstrated by comparing them with the available experimental measurements and theoretical calculations. The energy levels are accurate to 3.5eV, the wavelengths to within 15mÅ. For most transitions, the radiative rates an accuracy of 20%. The effects of CI from high-energy configurations were investigated as well. (2 data files).

  3. Student voluntarism in transition.

    PubMed

    Garcia, S A; Clark, C; Walfish, S

    1979-01-01

    The university student volunteer as a social change agent is in a period of transition. There is no returning to the idealism and activism of the 1960s if this and future generations of students continue to see self-preservation and individual advancement as their only viable option here in America. In view of the changing nature of today's students, the conventional definitions of volunteers, such as Shultz's (1972) altruist, average, and pseudo-volunteer, must be reconsidered. Does the acceptance of minimal pay or demand for academic credit preclude one's being a true altruist? Further, is altruism a necessary or sufficient condition of voluntarism? While we must attempt to answer these questions, the purpose here was to suggest viable first steps in reviving and enhancing student voluntarism. Some of the most salient points are: (1) Student volunteers provide critically needed services to the community, (2) Students are increasingly demanding tangible personal and educational gains for services through voluntarism, (3) Faculty support is vital to student voluntarism and they should be encouraged to actively design their classes to integrate classroom theory and practice through volunteering, and (4) The community agencies served should be active participants in the faculty, student, agency triad, and not merely passive recipients of services. The future of student voluntarism must be viewed in the larger context of changes occurring in the society-at-large, such as cynicism, mistrust of authority figures and leaders, and a move away from altruism and toward symbiosis and/or individualism. There is widespread disillusionment with "band-aid" approaches to solving enormous social problems, i.e., trying to help the few while some of society's most fundamental structures guarantee the perpetuation of poverty, crime, and general anomie. The rekindling of the ideology of cooperative altruism will take ingenuity and tireless effort. Meanwhile, if community psychology

  4. Parity nonconservation in atomic Zeeman transitions

    SciTech Connect

    Angstmann, E. J.; Dinh, T. H.; Flambaum, V. V.

    2005-11-15

    We discuss the possibility of measuring nuclear anapole moments in atomic Zeeman transitions and perform the necessary calculations. Advantages of using Zeeman transitions include variable transition frequencies and the possibility of enhancement of parity nonconservation effects.

  5. Hadron-Quark Phase Transition

    SciTech Connect

    Cavagnoli, Rafael; Menezes, Debora P.; Providencia, Constanca

    2009-06-03

    In the present work we study the hadron-quarkphase transition with boson condensation by investigating the binodal surface and extending it to finite temperature in order to mimic the QCD phase diagram.

  6. ISS Update: Transit of Venus

    NASA Video Gallery

    ISS Update commentator Brandi Dean interviews Mario Runco, NASA astronaut, about Venus's transit across the sun on June 5, 2012. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #...

  7. Transition probabilities of Br II

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Absolute transition probabilities of the three most prominent visible Br II lines are measured in emission. Results compare well with Coulomb approximations and with line strengths extrapolated from trends in homologous atoms.

  8. Moved by a Rapid Transit

    NASA Astrophysics Data System (ADS)

    Bueter, C.

    2013-04-01

    Enticing by virtue of its predictability, historical utility, and spectacle, the transit of Venus is a niche event among astronomical phenomena. Though the value of a transit for scientific purposes is now diminished, the brief appearance of Venus silhouetted against the background of the Sun in 2004 moved the artistic community to celebrate the rare alignment. Artists of all ages combined old traditions with fresh technology to create a 21st-century tapestry of music, sculpture, paintings, glasswork, quilts, sky shows, and digital imagery. A full catalog of transit-related art generated over the centuries would feature the sampling of entries presented here and at the Moved by a Rapid Transit website.

  9. Bypass transition to turbulence and research Desiderata

    NASA Technical Reports Server (NTRS)

    Morkovin, M. V.

    1985-01-01

    Bypass transitions are seldom mentioned in texts or meetings on instability and transition to wall turbulence. The nature of a number of bypass transitions is illustrated by example. Until this characteristics is truly understood predicting transition on the basis of theory or statistically inadequate correlations (as they all are) entails risks that should be considered in justifying any design involving transition. A historical overview of bypass transition identified on blunt bodies is given.

  10. Universal Keplerian state transition matrix

    NASA Technical Reports Server (NTRS)

    Shepperd, S. W.

    1985-01-01

    A completely general method for computing the Keplerian state transition matrix in terms of Goodyear's universal variables is presented. This includes a new scheme for solving Kepler's problem which is a necessary first step to computing the transition matrix. The Kepler problem is solved in terms of a new independent variable requiring the evaluation of only one transcendental function. Furthermore, this transcendental function may be conveniently evaluated by means of a Gaussian continued fraction.

  11. Extended calculations of level and transition properties in the nitrogen isoelectronic sequence: Cr XVIII, Fe XX, Ni XXII, and Zn XXIV

    NASA Astrophysics Data System (ADS)

    Radžiūtė, L.; Ekman, J.; Jönsson, P.; Gaigalas, G.

    2015-10-01

    Extensive multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for 272 states of the 2s22p3, 2s2p4, 2p5, 2s22p23l, 2s2p33l, and 2p43l (l = 0,1,2) configurations in the nitrogen-like ions Cr XVIII, Fe XX, Ni XXII, and Zn XXIV. Valence, core-valence, and core-core electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the NIST database. Landé gJ-factors; hyperfine structures; isotope shifts; and radiative electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transition rates are given for all ions. The accuracy of the calculated energy levels is high enough to facilitate identification of observed spectral lines involving the 2l43l' configurations, for which experimental data are largely missing. Tables 5-21 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/582/A61

  12. The major synthetic evolutionary transitions.

    PubMed

    Solé, Ricard

    2016-08-19

    Evolution is marked by well-defined events involving profound innovations that are known as 'major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These 'synthetic' transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431528

  13. Gauge theory of glass transition

    NASA Astrophysics Data System (ADS)

    Vasin, Mikhail

    2011-05-01

    A new analytical approach for the description of the glass transition in a frustrated system is suggested. The theory is based on the non-equilibrium dynamics technique, and takes into account the interaction of the local order field with the massive gauge field, which describes frustration-induced plastic deformation. The glass transition is regarded as a phase transition interrupted because of the premature critical slowing-down of one of the degrees of freedom caused by the frustrations. It is shown that freezing of the system appears when the correlation length and relaxation time of the gauge field diverge. The Vogel-Fulcher-Tammann relation for the transition kinetics and the critical exponent for the nonlinear susceptibility, 2.5\\lesssim \\gamma \\leq 3 , are derived in the framework of the suggested approach. An expression for the temperature dependence of the heat capacity near to the glass transition is derived. This dependence is qualitatively in good agreement with experimental data. The presented theory reproduces the characteristic form of the langphiphirangt correlation function dependence on time, and explains the boson peak appearance on this curve. In addition, the function of the glass transition temperature value with cooling rate is derived; this dependence fully conforms with known experimental data.

  14. Transitions in turbulent rotating convection

    NASA Astrophysics Data System (ADS)

    Rajaei, Hadi; Alards, Kim; Kunnen, Rudie; Toschi, Federico; Clercx, Herman; Fluid Dynamics Lab Team

    2015-11-01

    This study aims to explore the flow transition from one state to the other in rotating Rayleigh-Bènard convection using Lagrangian acceleration statistics. 3D particle tracking velocimetry (3D-PTV) is employed in a water-filled cylindrical tank of equal height and diameter. The measurements are performed at the center and close to the top plate at a Rayleigh number Ra = 1.28e9 and Prandtl number Pr = 6.7 for different rotation rates. In parallel, direct numerical simulation (DNS) has been performed to provide detailed information on the boundary layers. We report the acceleration pdfs for different rotation rates and show how the transition from weakly to strongly rotating Rayleigh-Bènard affects the acceleration pdfs in the bulk and boundary layers. We observe that the shapes of the acceleration PDFs as well as the isotropy in the cell center are largely unaffected while crossing the transition point. However, acceleration pdfs at the top show a clear change at the transition point. Using acceleration pdfs and DNS data, we show that the transition between turbulent states is actually a boundary layer transition between Prandtl-Blasius type (typical of non-rotating convection) and Ekman type.

  15. Planetary transits and stellar variability

    NASA Astrophysics Data System (ADS)

    Aigrain, Suzanne

    2005-01-01

    This thesis focuses on the detection of extrasolar planets via the transit method, and more specifically addresses issues relevant to the preparation of upcoming space missions such as CoRoT, Kepler, Eddington, aiming to detect terrestrial planets. The automated detection of transits in tens of thousands of noisy light curves is a challenging task because of the brief, shallow and rare nature of the sought-after signal. I developed a Bayesian transit detection algorithm and tested it through Monte Carlo simulations. This led to a number of improvements to the algorithm, resulting in a maximum likelihood box-fitting approach that is simpler and, for detection purposes, more effective. I also developed an empirical model of the intrinsic micro-variability of the parent stars, which constitutes one of the main performance limitations for space-based transit searches, and used this model to optimise variability filters. These tools were used to identify optimal regions of the stellar parameter space to be targeted by missions such as CoRoT and Eddington, through Monte Carlo simulations and participation in the first CoRoT blind transit detection exercise. Recently, the same tools have been used to analyse ground-based data from the University of New South Wales planet search project, leading to the identification of several potential transiting planet candidates.

  16. Unstable supercritical discontinuous percolation transitions

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Cheng, Xueqi; Zheng, Zhiming; Chung, Ning Ning; D'Souza, Raissa M.; Nagler, Jan

    2013-10-01

    The location and nature of the percolation transition in random networks is a subject of intense interest. Recently, a series of graph evolution processes have been introduced that lead to discontinuous percolation transitions where the addition of a single edge causes the size of the largest component to exhibit a significant macroscopic jump in the thermodynamic limit. These processes can have additional exotic behaviors, such as displaying a “Devil's staircase” of discrete jumps in the supercritical regime. Here we investigate whether the location of the largest jump coincides with the percolation threshold for a range of processes, such as Erdős-Rényipercolation, percolation via edge competition and via growth by overtaking. We find that the largest jump asymptotically occurs at the percolation transition for Erdős-Rényiand other processes exhibiting global continuity, including models exhibiting an “explosive” transition. However, for percolation processes exhibiting genuine discontinuities, the behavior is substantially richer. In percolation models where the order parameter exhibits a staircase, the largest discontinuity generically does not coincide with the percolation transition. For the generalized Bohman-Frieze-Wormald model, it depends on the model parameter. Distinct parameter regimes well in the supercritical regime feature unstable discontinuous transitions—a novel and unexpected phenomenon in percolation. We thus demonstrate that seemingly and genuinely discontinuous percolation transitions can involve a rich behavior in supercriticality, a regime that has been largely ignored in percolation.

  17. Modelling the transitional boundary layer

    NASA Technical Reports Server (NTRS)

    Narasimha, R.

    1990-01-01

    Recent developments in the modelling of the transition zone in the boundary layer are reviewed (the zone being defined as extending from the station where intermittency begins to depart from zero to that where it is nearly unity). The value of using a new non-dimensional spot formation rate parameter, and the importance of allowing for so-called subtransitions within the transition zone, are both stressed. Models do reasonably well in constant pressure 2-dimensional flows, but in the presence of strong pressure gradients further improvements are needed. The linear combination approach works surprisingly well in most cases, but would not be so successful in situations where a purely laminar boundary layer would separate but a transitional one would not. Intermittency-weighted eddy viscosity methods do not predict peak surface parameters well without the introduction of an overshooting transition function whose connection with the spot theory of transition is obscure. Suggestions are made for further work that now appears necessary for developing improved models of the transition zone.

  18. Boundary layer transition studies

    NASA Technical Reports Server (NTRS)

    Watmuff, Jonathan H.

    1995-01-01

    A small-scale wind tunnel previously used for turbulent boundary layer experiments was modified for two sets of boundary layer transition studies. The first study concerns a laminar separation/turbulent reattachment. The pressure gradient and unit Reynolds number are the same as the fully turbulent flow of Spalart and Watmuff. Without the trip wire, a laminar layer asymptotes to a Falkner & Skan similarity solution in the FPG. Application of the APG causes the layer to separate and a highly turbulent and approximately 2D mean flow reattachment occurs downstream. In an effort to gain some physical insight into the flow processes a small impulsive disturbance was introduced at the C(sub p) minimum. The facility is totally automated and phase-averaged data are measured on a point-by-point basis using unprecedently large grids. The evolution of the disturbance has been tracked all the way into the reattachment region and beyond into the fully turbulent boundary layer. At first, the amplitude decays exponentially with streamwise distance in the APG region, where the layer remains attached, i.e. the layer is viscously stable. After separation, the rate of decay slows, and a point of minimum amplitude is reached where the contours of the wave packet exhibit dispersive characteristics. From this point, exponential growth of the amplitude of the disturbance is observed in the detached shear layer, i.e. the dominant instability mechanism is inviscid. A group of large-scale 3D vortex loops emerges in the vicinity of the reattachment. Remarkably, the second loop retains its identify far downstream in the turbulent boundary layer. The results provide a level of detail usually associated with CFD. Substantial modifications were made to the facility for the second study concerning disturbances generated by Suction Holes for laminar flow Control (LFC). The test section incorporates suction through interchangeable porous test surfaces. Detailed studies have been made using isolated

  19. Transition boiling heat transfer and the film transition regime

    NASA Technical Reports Server (NTRS)

    Ramilison, J. M.; Lienhard, J. H.

    1987-01-01

    The Berenson (1960) flat-plate transition-boiling experiment has been recreated with a reduced thermal resistance in the heater, and an improved access to those portions of the transition boiling regime that have a steep negative slope. Tests have been made in Freon-113, acetone, benzene, and n-pentane boiling on horizontal flat copper heaters that have been mirror-polished, 'roughened', or teflon-coated. The resulting data reproduce and clarify certain features observed by Berenson: the modest surface finish dependence of boiling burnout, and the influence of surface chemistry on both the minimum heat flux and the mode of transition boiling, for example. A rational scheme of correlation yields a prediction of the heat flux in what Witte and Lienhard (1982) previously identified as the 'film-transition boiling' region. It is also shown how to calculate the heat flux at the boundary between the pure-film, and the film-transition, boiling regimes, as a function of the advancing contact angle.

  20. Major transitions in human evolution

    PubMed Central

    Foley, Robert A.; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris

    2016-01-01

    Evolutionary problems are often considered in terms of ‘origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue ‘Major transitions in human evolution’ throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation—genes, phenotypes and behaviour—integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298461

  1. Electronic Transitions of Scandium Monophosphide

    NASA Astrophysics Data System (ADS)

    Wang, Na; Ng, Kiu Fung; Cheung, Allan S. C.

    2014-06-01

    The electronic transition spectrum of scandium monophosphide (ScP) molecule in the visible region between 480 nm and 550 nm has been recorded and analyzed using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The ScP molecule was produced by reacting laser - ablated scandium atoms with PH3 seeded in argon. Ten vibrational bands were recorded and they are identified to be belonging to three electronic transition systems, namely the [19.1]1 Π_1 - X1 Σ transition, [19.5]1 Σ - X1 Σ transition, and [19.8] 3 Π_i - X3 Π_i transition. ScP has been determined to have a X1 Σ ground state in our earlier work. A least squares fit of the measured rotational lines yielded molecular constants for the single and the triplet electronic states. Theoretical calculation results have been used to help the assignment of the observed electronic states.

  2. Electronic transitions of cobalt monoboride.

    PubMed

    Ng, Y W; Pang, H F; Cheung, A S-C

    2011-11-28

    Electronic transition spectrum of cobalt monoboride (CoB) in the visible region between 495 and 560 nm has been observed and analyzed using laser-induced fluorescence spectroscopy. CoB molecule was produced by the reaction of laser-ablated cobalt atom and diborane (B(2)H(6)) seeded in argon. Fifteen vibrational bands with resolved rotational structure have been recorded, which included transitions of both Co(10)B and Co(11)B isotopic species. Our analysis showed that the observed transition bands are ΔΩ = 0 transitions with Ω" = 2 and Ω" = 3 lower states. Four transition systems have been assigned, namely, the [18.1](3)Π(2)-X(3)Δ(2), the [18.3](3)Φ(3)-X(3)Δ(3), the [18.6]3- X(3)Δ(3), and the [19.0]2-X(3)Δ(2) systems. The bond length, r(o), of the X(3)Δ(3) state of CoB is determined to be 1.705 Å. The observed rotational lines showed unresolved hyperfine structure arising from the nuclei, which conforms to the Hund's case (a(β)) coupling scheme. This work represents the first experimental investigation of the CoB spectrum. PMID:22128936

  3. Major transitions in human evolution.

    PubMed

    Foley, Robert A; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris

    2016-07-01

    Evolutionary problems are often considered in terms of 'origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue 'Major transitions in human evolution' throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation-genes, phenotypes and behaviour-integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized.This article is part of the themed issue 'Major transitions in human evolution'. PMID:27298461

  4. The major synthetic evolutionary transitions

    PubMed Central

    Solé, Ricard

    2016-01-01

    Evolution is marked by well-defined events involving profound innovations that are known as ‘major evolutionary transitions'. They involve the integration of autonomous elements into a new, higher-level organization whereby the former isolated units interact in novel ways, losing their original autonomy. All major transitions, which include the origin of life, cells, multicellular systems, societies or language (among other examples), took place millions of years ago. Are these transitions unique, rare events? Have they instead universal traits that make them almost inevitable when the right pieces are in place? Are there general laws of evolutionary innovation? In order to approach this problem under a novel perspective, we argue that a parallel class of evolutionary transitions can be explored involving the use of artificial evolutionary experiments where alternative paths to innovation can be explored. These ‘synthetic’ transitions include, for example, the artificial evolution of multicellular systems or the emergence of language in evolved communicating robots. These alternative scenarios could help us to understand the underlying laws that predate the rise of major innovations and the possibility for general laws of evolved complexity. Several key examples and theoretical approaches are summarized and future challenges are outlined. This article is part of the themed issue ‘The major synthetic evolutionary transitions’. PMID:27431528

  5. Optical feshbach resonance using the intercombination transition.

    PubMed

    Enomoto, K; Kasa, K; Kitagawa, M; Takahashi, Y

    2008-11-14

    We report control of the scattering wave function by an optical Feshbach resonance effect using ytterbium atoms. The narrow intercombination line (1S0-3P1) is used for efficient control as proposed by Ciuryło et al. [Phys. Rev. A 71, 030701(R) (2005)10.1103/PhysRevA.71.030701]. The manipulation of the scattering wave function is monitored with the change of a photoassociation rate caused by another laser. The optical Feshbach resonance is especially efficient for isotopes with large negative scattering lengths such as 172Yb, and we have confirmed that the scattering phase shift divided by the wave number, which gives the scattering length in the zero energy limit, is changed by about 30 nm. PMID:19113335

  6. 7 CFR 15a.18 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 1 2013-01-01 2013-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...

  7. 7 CFR 15a.18 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 1 2011-01-01 2011-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...

  8. 36 CFR 1211.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Transition plans. 1211.230... FINANCIAL ASSISTANCE Coverage § 1211.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...

  9. 10 CFR 5.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...

  10. 44 CFR 19.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Transition plans. 19.230... RECEIVING FEDERAL FINANCIAL ASSISTANCE Coverage § 19.230 Transition plans. (a) Submission of plans. An... submit either a single transition plan applicable to all such units, or a separate transition...

  11. 10 CFR 5.230 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...

  12. 45 CFR 2555.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 4 2012-10-01 2012-10-01 false Transition plans. 2555.230 Section 2555.230 Public... Coverage § 2555.230 Transition plans. (a) Submission of plans. An institution to which § 2555.225 applies... transition plan applicable to all such units, or a separate transition plan applicable to each such unit....

  13. 7 CFR 15a.18 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 1 2012-01-01 2012-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...

  14. 32 CFR 196.230 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 2 2013-07-01 2013-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...

  15. 36 CFR 1211.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Transition plans. 1211.230... FINANCIAL ASSISTANCE Coverage § 1211.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...

  16. 7 CFR 15a.18 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 1 2014-01-01 2014-01-01 false Transition plans. 15a.18 Section 15a.18 Agriculture... FEDERAL FINANCIAL ASSISTANCE Coverage § 15a.18 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...

  17. 32 CFR 196.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 2 2012-07-01 2012-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...

  18. 29 CFR 36.230 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 1 2014-07-01 2013-07-01 true Transition plans. 36.230 Section 36.230 Labor Office of the... FEDERAL FINANCIAL ASSISTANCE Coverage § 36.230 Transition plans. (a) Submission of plans. An institution... submit either a single transition plan applicable to all such units, or a separate transition...

  19. 32 CFR 196.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 2 2011-07-01 2011-07-01 false Transition plans. 196.230 Section 196.230... FINANCIAL ASSISTANCE Coverage § 196.230 Transition plans. (a) Submission of plans. An institution to which... a single transition plan applicable to all such units, or a separate transition plan applicable...

  20. 10 CFR 5.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Transition plans. 5.230 Section 5.230 Energy NUCLEAR... FEDERAL FINANCIAL ASSISTANCE Coverage § 5.230 Transition plans. (a) Submission of plans. An institution to... either a single transition plan applicable to all such units, or a separate transition plan applicable...

  1. 42 CFR 412.533 - Transition payments.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Transition payments. 412.533 Section 412.533 Public... Hospitals § 412.533 Transition payments. (a) Duration of transition periods. Except for a long-term care... reconciliation of cost reports. (c) Election not to be paid under the transition period methodology. A...

  2. 42 CFR 412.626 - Transition period.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Transition period. 412.626 Section 412.626 Public... Hospitals and Rehabilitation Units § 412.626 Transition period. (a) Duration of transition period and proportion of the blended transition rate. (1) Except for a facility that makes an election under...

  3. 42 CFR 136a.31 - Transition period.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Transition period. 136a.31 Section 136a.31 Public... OF HEALTH AND HUMAN SERVICES INDIAN HEALTH Transition Provisions § 136a.31 Transition period. (a) The transition period for full implementation of the new eligibility regulations consists of three parts; (1)...

  4. Alternative approaches to fertility transition.

    PubMed

    Micheli, G A

    1995-01-01

    "Using anomalies of the Italian case as the basis, the aim of this article is to verify how the theoretical framework [of demographic transition] put forward by Lesthaeghe can be interpreted.... While the changes in mores in the Italy of the economic boom were a component of the large-scale processes of secularization, rationalization and modernization specific to the [first demographic transition], the practices, values and models of the collective imagination characterizing the second phase of Lesthaeghe's [second demographic transition] are marked by a state of mind that cannot be put down to the 'spirit of the age' during the years of large-scale modernization, but to the emancipatory and 'rational' falling away of many of the barriers to the unfolding of individual life destiny over and above that based on class, gender and age." PMID:12291784

  5. Mott transition in granular aluminum

    NASA Astrophysics Data System (ADS)

    Bachar, N.; Lerer, S.; Levy, A.; Hacohen-Gourgy, S.; Almog, B.; Saadaoui, H.; Salman, Z.; Morenzoni, E.; Deutscher, G.

    2015-01-01

    A Mott transition in granular Al films is observed by probing the increase of the spin-flip scattering rate of conduction electrons as the nanosize metallic grains are being progressively decoupled. The presence of free spins in granular Al films is directly demonstrated by μ SR measurements. Analysis of the magnetoresistance in terms of an effective Fermi energy shows that it becomes of the order of the grains electrostatic charging energy at a room temperature resistivity ρ300 K≈50000 μ Ω cm , at which a metal to insulator transition is known to exist. As this transition is approached the magnetoresistance exhibits a heavy-fermion-like behavior, consistent with an increased electron effective mass.

  6. Electronic transitions of iridium monophosphide

    NASA Astrophysics Data System (ADS)

    Yang, M.; Chan, Man-Chor; Cheung, A. S.-C.

    2016-05-01

    Laser induced fluorescence spectrum of IrP in the near infrared spectral region between 720 and 820 nm has been recorded and analyzed. Six vibrational bands with resolved rotational structure for both 191IrP and 193IrP were analyzed, they have been grouped into three new electronic transitions: the [13.6] Ω = 2 - a3Π2, the [12.3]1Π1-X1Σ+, and the [12.7]1Π1-X1Σ+ transitions. Ab initio calculation results were used to aid the assignment of the observed transitions. A new triplet state has been observed for the first time. The observed electronic states of IrP are compared with those of the isovalent IrN molecule.

  7. Transition metals in superheat melts

    NASA Technical Reports Server (NTRS)

    Jakes, Petr; Wolfbauer, Michael-Patrick

    1993-01-01

    A series of experiments with silicate melts doped with transition element oxides was carried out at atmospheric pressures of inert gas at temperatures exceeding liquidus. As predicted from the shape of fO2 buffer curves in T-fO2 diagrams the reducing conditions for a particular oxide-metal pair can be achieved through the T increase if the released oxygen is continuously removed. Experimental studies suggest that transition metals such as Cr or V behave as siderophile elements at temperatures exceeding liquidus temperatures if the system is not buffered by the presence of other oxide of more siderophile element. For example the presence of FeO prevents the reduction of Cr2O3. The sequence of decreasing siderophility of transition elements at superheat conditions (Mo, Ni, Fe, Cr) matches the decreasing degree of depletion of siderophile elements in mantle rocks as compared to chondrites.

  8. [The epidemiological transition in Chile].

    PubMed

    Albalá, C; Vio, F; Robledo, A; Icaza, G

    1993-12-01

    Aiming to describe the place that Chile has in the epidemiological transition, a descriptive study of the changes in demographic and epidemiological profiles of the country during the last 30 years is presented. The important decrease in general and child mortality rates, that has lead to an increase in life expectancy and ageing of the population, is emphasized. A 82% reduction in the proportion of deaths among less than one year old children and a 62% increase in mortality among people 65 years or older is observed. In agreement with these changes, non transmissible chronic diseases appear as the principal cause of mortality (65% of all deaths). However, regarding morbidity, an increase in digestive infectious and sexually transmitted diseases and a decrease in immuno-preventable diseases, excepting measles, is noted. It is concluded that, according to mortality, Chile is in a post transition stage, but there is persistence of some infectious diseases, typical of a pre-transition stage. PMID:8085073

  9. Transitions in individuality through symbiosis.

    PubMed

    Estrela, Sylvie; Kerr, Benjamin; Morris, J Jeffrey

    2016-06-01

    When a more complex, functionally integrated entity emerges from the association of simpler, initially independent entities, a major evolutionary transition has occurred. Transitions that result from the association of different species include the evolution of the eukaryotic cell and some obligate mutualisms. Recent studies are revolutionizing our understanding of how these intimate interspecific associations come to be, revealing how and to what extent each partner contributes to the relationship, and how partners mediate conflict. Here, we review work on the evolution of mutualistic symbioses in the context of transitions in individuality and highlight how a better mechanistic understanding of the ecological drivers of host-symbiont interdependencies can help elucidate the evolutionary path to symbiotic organismality. PMID:27131019

  10. Understanding epidemiological transition in India

    PubMed Central

    Yadav, Suryakant; Arokiasamy, Perianayagam

    2014-01-01

    Background Omran's theory explains changing disease patterns over time predominantly from infectious to chronic noncommunicable diseases (NCDs). India's epidemiological transition is characterized by dual burden of diseases. Kumar addressed low mortality and high morbidity in Kerala, which seems also to be true for India as a country in the current demographic scenario. Methods NSS data (1986–1987, 1995–1996, 2004) and aggregated data on causes of death provided by Registrar General India (RGI) were used to examine the structural changes in morbidity and causes of death. A zero-inflated poisson (ZIP) regression model and a beta-binomial model were used to corroborate the mounting age pattern of morbidity. Measures, namely the 25th and 75th percentiles of age-at-death and modal age-at-death, were used to examine the advances in mortality transition. Objective This study addressed the advances in epidemiological transition via exploring the structural changes in pattern of diseases and progress in mortality transition. Results The burden of NCDs has been increasing in old age without replacing the burden of communicable diseases. The manifold rise of chronic diseases in recent decades justifies the death toll and is responsible for transformation in the age pattern of morbidity. Over time, deaths have been concentrated near the modal age-at-death. Modal age-at-death increased linearly by 5 years for females (r2=0.9515) and males (r2=0.9020). Significant increase in modal age-at-death ascertained the dominance of old age mortality over the childhood/adult age mortality. Conclusions India experiences a dual burden of diseases associated with a remarkable transformation in the age pattern of morbidity and mortality, contemporaneous with structural changes in disease patterns. Continued progress in the pattern of diseases and mortality transition, accompanied by a linear rise in ex, unravels a compelling variation in advances found so far in epidemiological

  11. Transition probabilities and static moments in transitional nuclei

    SciTech Connect

    Wolf, A.; Casten, R.F.

    1988-01-01

    Electromagnetic transition probabilities and static moments of excited nuclear states are known to be good probes of nuclear structure. Therefore, a systematic analysis of the large amount of existing experimental data for these observables is expected to provide valuable information about the respective isotopes. It is the purpose of this talk to show that a combined analysis of static magnetic moments of 2/sub 1//sup +/ states and B(E2) transition probabilities for even-even nuclei can be used to obtain effective numbers of valence nucleons. This kind of information is of particular interest in cases where subshell closures are found. For example, it is well known that for the transitional nuclei in the A = 150 region the Z = 64 subshell is active when the number of neutrons N < 90, but disappears for N greater than or equal to 90. A similar situation exists in the A = 100 region, where the Z = 38 subshell is active for N less than or equal to 58. In the following sections we present the method by which effective numbers of valence protons and neutrons can be deduced from B(E2) and g-factor data, and show applications of this method to the A = 150 and A = 100 transitional regions. Part of these results were recently published.

  12. Presidential Transition Teams: Fostering a Collaborative Transition Process

    ERIC Educational Resources Information Center

    Artman, Richard B.; Franz, Mark

    2009-01-01

    Whether hiring a sitting president or one beginning a first presidency, the board of trustees should be keenly interested in ensuring that the new president's first months in office flow as smoothly as possible. Increasing attention has been paid in recent years to the idea of using a transition team to assist the new president. Using a transition…

  13. Theoretical Studies of Atomic Transitions

    SciTech Connect

    Charlotte Froese Fischer

    2005-07-08

    Atomic structure calculations were performed for properties such as energy levels, binding energies, transition probabilities, lifetimes, hyperfine structure, and isotope shifts. Accurate computational procedures were devised so that properties could be predicted even when they could not be obtained from experiment, and to assist in the identification of observed data. The method used was the multiconfiguration Hartree-Fock (MCHF) method, optionally corrected for relativistic effects in the Breit-Pauli approximation. Fully relativistic Dirac-Fock calculations also were performed using the GRASP code A database of energy levels, lifetimes, and transition probabilities was designed and implemented and, at present, includes many results for Be-like to Ar-like.

  14. Numerical simulation of transitional flow

    NASA Technical Reports Server (NTRS)

    Biringen, Sedat

    1986-01-01

    The applicability of active control of transition by periodic suction-blowing is investigated via direct simulations of the Navier-Stokes equations. The time-evolution of finite-amplitude disturbances in plane channel flow is compared in detail with and without control. The analysis indicates that, for relatively small three-dimensional amplitudes, a two-dimensional control effectively reduces disturbance growth rates even for linearly unstable Reynolds numbers. After the flow goes through secondary instability, three-dimensional control seems necessary to stabilize the flow. An investigation of the temperature field suggests that passive temperature contamination is operative to reflect the flow dynamics during transition.

  15. William Crabtree's Venus transit observation

    NASA Astrophysics Data System (ADS)

    Kollerstrom, Nicholas

    2005-04-01

    The close collaboration between the two North-country astronomers Jeremiah Horrocks and William Crabtree gave them special insight into the new astronomy published by the recently-deceased Kepler, whereby Horrocks became the only person to apprehend that the Rudolphine tables were in fact predicting a Venus transit in 1639. This paper focuses especially upon William Crabtree's role and contribution. A comparison is made with an earlier, unsuccessful endeavour by these two concerning a possible transit of Mercury. Much of the record of their work was lost during the civil war. Finally, thanks to Christiaan Huygens, Horrock's manuscript was published by Johannes Hevelius in Danzig, in 1662.

  16. Epigenetic switches and network transitions

    NASA Astrophysics Data System (ADS)

    Sasai, Masaki

    2012-02-01

    We investigate dynamics of gene networks which are regulated by both the fast binding/unbinding of transcription factors to/from DNA and the slow processes of chromatin structural change or histone modification. This heterogeneous dynamics consisting of different time scales is analyzed by the mean-field approximation and the stochastic simulation to show that the network exhibits multiple metastable states and is characterized by transitions among them. We discuss distribution and fluctuation of states of the core gene network of embryonic stem cells as an example of such heterogeneous dynamics and the simulated transitions are compared with the experimental data on the distribution of stem cell states.

  17. Colloquium: Water's controversial glass transitions

    NASA Astrophysics Data System (ADS)

    Amann-Winkel, Katrin; Böhmer, Roland; Fujara, Franz; Gainaru, Catalin; Geil, Burkhard; Loerting, Thomas

    2016-01-01

    Water is the most common and, judged from its numerous anomalous properties, the weirdest of all known liquids and the complexity of its pressure-temperature map is unsurpassed. A major obstacle on the way to a full understanding of water's structure and dynamics is the hard-to-explore territory within this map, colloquially named the no man's land. Many experiments suggest that just before stepping across its low-temperature border, amorphous ices undergo glass-to-liquid transitions while other interpretations emphasize the importance of underlying disordered (nano)crystalline states. Prospects for reconciling the conflicting views regarding the nature of water's glass transitions are discussed.

  18. The migration transition in Malaysia.

    PubMed

    Lim, L L

    1996-01-01

    "Exploring the unique experience of migration transition in Malaysia, this paper identifies the turning points in relation to the level and nature of economic and labor market developments in Malaysia. Examining the development dynamics that mark the passage from exporting labor to depending on foreign labor, the paper concludes that such dynamics are influenced not only by economic but also sociocultural, demographic and policy factors. Several lessons from the Malaysian experience are drawn at the end to be utilized by other countries that still have to reach the turning points of the migration transition." PMID:12320775

  19. Dynamic Transitions of Generalized Burgers Equation

    NASA Astrophysics Data System (ADS)

    Li, Limei; Ong, Kiah Wah

    2016-03-01

    In this article, we study the dynamic transition for the one dimensional generalized Burgers equation with periodic boundary condition. The types of transition are dictated by the sign of an explicitly given parameter b, which is derived using the dynamic transition theory developed by Ma and Wang (Phase transition dynamics. Springer, New York, 2014). The rigorous result demonstrates clearly the types of dynamics transition in terms of length scale l, dispersive parameter δ and viscosity ν.

  20. Magnetic dipole transitions in the hydrogen molecule

    SciTech Connect

    Pachucki, Krzysztof; Komasa, Jacek

    2011-03-15

    In homonuclear molecules, such as H{sub 2}, the electric dipole transitions are strongly forbidden, and the transitions between rovibrational states are of the electric quadrupole type. We show, however, that magnetic dipole transitions also take place, although they are significantly weaker. We evaluate the probabilities of such transitions between several of the lowest rotational states and compare them with those of the corresponding electric quadrupole transitions.

  1. Transition metal-free intramolecular regioselective couplings of aliphatic and aromatic C-H bonds.

    PubMed

    Tian, Hua; Yang, Haijun; Zhu, Changjin; Fu, Hua

    2016-01-01

    Cross-dehydrogenative couplings of two different C-H bonds have emerged as an attractive goal in organic synthesis. However, achieving regioselective C-H activation is a great challenge because C-H bonds are ubiquitous in organic compounds. Actually, the regioselective couplings promoted by enzymes are a common occurrence in nature. Herein, we have developed simple, efficient and general transition metal-free intramolecular couplings of alphatic and aromatic C-H bonds. The protocol uses readily available aryl triazene as the radical initiator, cheap K2S2O8 as the oxidant, and the couplings were performed well with excellent tolerance of functional groups. Interestingly, α-carbon configuration of some amino acid residues in the substrates was kept after the reactions, and the couplings for substrates with substituted phenylalanine residues exhibited complete β-carbon diastereoselectivity for induction of the chiral α-carbon. Therefore, the present study should provide a novel strategy for regioselective cross-dehydrogenative couplings of two different C-H bonds. PMID:26822836

  2. Transition metal-free intramolecular regioselective couplings of aliphatic and aromatic C-H bonds

    PubMed Central

    Tian, Hua; Yang, Haijun; Zhu, Changjin; Fu, Hua

    2016-01-01

    Cross-dehydrogenative couplings of two different C-H bonds have emerged as an attractive goal in organic synthesis. However, achieving regioselective C-H activation is a great challenge because C-H bonds are ubiquitous in organic compounds. Actually, the regioselective couplings promoted by enzymes are a common occurrence in nature. Herein, we have developed simple, efficient and general transition metal-free intramolecular couplings of alphatic and aromatic C-H bonds. The protocol uses readily available aryl triazene as the radical initiator, cheap K2S2O8 as the oxidant, and the couplings were performed well with excellent tolerance of functional groups. Interestingly, α-carbon configuration of some amino acid residues in the substrates was kept after the reactions, and the couplings for substrates with substituted phenylalanine residues exhibited complete β-carbon diastereoselectivity for induction of the chiral α-carbon. Therefore, the present study should provide a novel strategy for regioselective cross-dehydrogenative couplings of two different C-H bonds. PMID:26822836

  3. Transition probabilities for the UV0.01 multiplet in N III

    NASA Technical Reports Server (NTRS)

    Brage, Tomas; Fischer, Charlotte Froese; Judge, Philip G.

    1995-01-01

    We report on large-scale ab initio multiconfiguration Hartree-Fock calculations for the UV0.01 multiplet, 2s(sup 2)2p(sup 2)P(sub J) - 2s2p(sup 2 4)P(sub J prime), in N III. The resulting transition probabilities agree very well with recent semiempirical calculations, and the lifetimes for two of the three upper levels agree with experiments. The deviation for the third level is discussed. Comparisons made with the highest quality IUE echelle spectra available -- those of RR Tel and V1016 Cyg (both photoionized sources with electron densities below 10(exp 8)/cu cm) -- show that computed branching ratios of lines sharing a common upper level are in agreement with observations to within uncertainties of +/- 10%. High-quality solar limb data or stellar data from the Hubble Space Telescope (HST) could, in principle, be used to determine whether the theoretical or measured lifetimes for the discrepant level are in error. Unfortunately, stellar data for high-density plasmas (N(sub e) greater than 10(exp 11)/cu cm are needed) do not yet exist, and existing solar data lack the photometric precision to address this problem.

  4. Magnetic-dipole transition probabilities in B-like and Be-like ions

    SciTech Connect

    Tupitsyn, I. I.; Glazov, D. A.; Volotka, A. V.; Shabaev, V. M.; Plunien, G.; Crespo Lopez-Urrutia, J. R.; Lapierre, A.; Ullrich, J.

    2005-12-15

    The magnetic-dipole transition probabilities between the fine-structure levels (1s{sup 2}2s{sup 2}2p) {sup 2}P{sub 1/2}-{sup 2}P{sub 3/2} for B-like ions and (1s{sup 2}2s2p) {sup 3}P{sub 1}-{sup 3}P{sub 2} for Be-like ions are calculated. The configuration-interaction method in the Dirac-Fock-Sturm basis is employed for the evaluation of the interelectronic-interaction correction with negative-continuum spectrum being taken into account. The 1/Z interelectronic-interaction contribution is derived within a rigorous QED approach employing the two-time Green function method. The one-electron QED correction is evaluated within framework of the anomalous magnetic-moment approximation. A comparison with the theoretical results of other authors and with available experimental data is presented.

  5. New Bottomonium Spectroscopy And Transitions

    SciTech Connect

    West, Chris; /SLAC

    2011-12-01

    Recent results in bottomonium spectroscopy are reviewed. Topics include the observation of {Upsilon}(nS) {yields} {eta}{Upsilon}(1S) transitions, energy scans above the {Upsilon}(4S) resonance by the BABAR and Belle experiments, and the recent observation of the {eta}{sub b} by the BABAR experiment.

  6. The Transition to Work Simulator.

    ERIC Educational Resources Information Center

    Conroy, William G., Jr.

    1979-01-01

    This report describes the Transition to Work Simulator (TWS), a computerized model of the important career decisions which people make from youth through midcareer. The implications of TWS as a planning tool for human resource development at the national level are discussed. (Author/SJL)

  7. Transitive Softening in Russian Conjugation

    ERIC Educational Resources Information Center

    Coats, H. S.; Lightner, T. M.

    1975-01-01

    Transitive softening, or the shift of a dental or velar to a palato-alveolar, and the insertion of a palatalized /1/ after a labial, are examined. The older transformational cycle of Halle is set aside in favor of a morphological rule. Productive and non-productive verb classes are analyzed. (SC)

  8. Poland's Transition in Business Education

    ERIC Educational Resources Information Center

    Leven, Bozena

    2010-01-01

    Prior to Poland's transition from central planning to a market system, which began in 1990, schools of business were non-existent in that country. Instead, university level instruction on economics during the socialist period was closely tied to ideological priorities, and limited to imparting skills suitable for planned economy. All universities…

  9. Menopause: A Life Cycle Transition.

    ERIC Educational Resources Information Center

    Evarts, Barbara Kess; Baldwin, Cynthia

    1998-01-01

    Family therapists need to address the issue of menopause proactively to be of benefit to couples and families during this transitional period in the family life cycle. Physical, psychological, and psychosocial factors affecting the menopausal woman and her family, and ways to address these issues in counseling are discussed. (Author/EMK)

  10. Electrical Conductivity in Transition Metals

    ERIC Educational Resources Information Center

    Talbot, Christopher; Vickneson, Kishanda

    2013-01-01

    The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…

  11. Sustainability Transitions as new perspective

    NASA Astrophysics Data System (ADS)

    Rotmans, J.

    2012-04-01

    Sustainability transitions are radical transformations towards a sustainable society as a response to a number of persistent problems confronting contemporary modern societies. The most striking example of such a persistent problem is the current economic and financial crisis. This crisis is only a symptom of a deeper-lying systems crisis, which is rooted in the disbalance between overly consuming and producing during the last decennia on the one hand and exhausting our natural resources and materials on the other hand. The perverse effects of this disbalance are not accounted for in the economic order that we have created. This means that the economic order is not sustainable in the long run. Without a fundamental shift, a transition, to a new, sustainable economy, we will revert to old patterns and mechanisms that will automatically generate the next crises. In this transition process we are at a turning point. On the verge of a new era, characterized by a battle of the old paradigm against the new one, with a crucial role for sustainable innovation. Such a transition perspective might help to unravel the unprecedented complexity of the interrelated economic, financial, energy and climate crisis and to shed some light on structural, sustainable solutions.

  12. American Higher Education in Transition

    ERIC Educational Resources Information Center

    Ehrenberg, Ronald G.

    2011-01-01

    American higher education is in transition and if there ever was a "golden age" for faculty, it probably is behind us. The best historical data on the composition of faculty is collected annually by the American Mathematical Society. Between 1967 and 2009, the share of full-time faculty with PhDs remained constant at about 90 percent at doctoral…

  13. Transiting Exoplanet Survey Satellite (TESS)

    NASA Technical Reports Server (NTRS)

    Ricker, G. R.; Clampin, M.; Latham, D. W.; Seager, S.; Vanderspek, R. K.; Villasenor, J. S.; Winn, J. N.

    2012-01-01

    The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey, TESS will monitor more than 500,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat. A large fraction of TESS target stars will be 30-100 times brighter than those observed by Kepler satellite, and therefore TESS . planets will be far easier to characterize with follow-up observations. TESS will make it possible to study the masses, sizes, densities, orbits, and atmospheres of a large cohort of small planets, including a sample of rocky worlds in the habitable zones of their host stars. TESS will provide prime targets for observation with the James Webb Space Telescope (JWST), as well as other large ground-based and space-based telescopes of the future. TESS data will be released with minimal delay (no proprietary period), inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the very nearest and brightest main-sequence stars hosting transiting exoplanets, thus providing future observers with the most favorable targets for detailed investigations.

  14. "Mexico in Transition." Curriculum Units.

    ERIC Educational Resources Information Center

    Oregon Univ., Eugene. Foreign Language Resource Center.

    These curriculum units were developed in a National Endowment for the Humanities 1994 summer seminar "Mexico in Transition." The 23 lessons are written in Spanish. Lessons are entitled: (1) "La Migracion Mexicana Vista a Traves del Cuento 'Paso del Norte' de Juan Rulfo" (Jose Jorge Armendariz); (2) "Los Grupos Indigenas de Mexico: Condiciones…

  15. Career Transitions: The Australian Experience.

    ERIC Educational Resources Information Center

    Stevens, Paul

    This book is designed to aid career counselors in Australia help their clients search for enhanced well-being in their occupations and to help organizations and human resource staff members dealing with employees' career development. The book is organized in four parts. Parts 1 and 2 explore the career transition journey that a typical person…

  16. Electronic transitions of yttrium monophosphide

    NASA Astrophysics Data System (ADS)

    Li, Biu Wa; Chan, Man-Chor; Cheung, A. S.-C.

    2015-11-01

    The electronic transition spectrum of the yttrium monophosphide (YP) molecule in the near infrared region between 715 nm and 880 nm has been recorded using laser ablation/reaction free-jet expansion and laser induced fluorescence spectroscopy. The YP molecule was produced by reacting laser - ablated yttrium atoms with PH3 gas seeded in argon. Eleven vibrational bands were analyzed and six electronic transitions have been identified, namely the [12.17] Ω = 3 - X3Π2, [13.27] Ω = 3 - X3Π2, [13.44] Ω = 3 - X3Π2, [13.46] Ω = 3 - X3Π2 and [13.40] Ω = 2 - X3Π2 transitions and a [13.69] Ω = 3 - a1Δ2 transition. Least squares fits of the measured rotational lines yielded molecular constants for the ground and excited states. The ground state has been determined to be a X3Π2 state and the bond length ro and vibrational separation, ΔG1/2, were determined to be 2.4413 Å and 390.77 cm-1 respectively. A molecular orbital energy level diagram has been used to aid the assignment of the observed electronic states. This work represents the first experimental investigation of the electronic spectrum of the YP molecule.

  17. Leadership Transitions: Keys for Success

    ERIC Educational Resources Information Center

    Goodyear, Marilu; Golden, Cynthia

    2008-01-01

    A leadership transition poses dangers and challenges for both leaders and followers. While each party naturally focuses on the organization's success, time needs to be spent on how the new relationships will develop and mature into effective working relationships. This article discusses the following four areas of interaction between leaders and…

  18. N-{Delta} weak transition

    SciTech Connect

    Graczyk, Krzysztof M.

    2011-11-23

    A short review of the Rein-Sehgal and isobar models is presented. The attention is focused on the nucleon-{Delta}(1232) weak transition form-factors. The results of the recent re-analyses of the ANL and BNL bubble chamber neutrino-deuteron scattering data are discussed.

  19. Postsecondary Transitions among Navajo Indians.

    ERIC Educational Resources Information Center

    Jackson, Aaron P.; Smith, Steven A.

    2001-01-01

    A study examining postsecondary transition experiences interviewed 22 Navajos who were recent high school graduates. Prominent themes included family influence and pressures, discrepancy between high school and college learning environments, student-faculty relationships, vague educational and career plans, misconceptions about postsecondary…

  20. Multiscaling behavior in transition economies

    NASA Astrophysics Data System (ADS)

    Litvin, Vladimir A.

    2004-12-01

    A comparable statistical analysis for the currency exchange rates of the countries with transition economies has been made. Self-criticality has been demonstrated and studied. Non-linear effect for self-criticality indexes has been demonstrated. All effects are essentially nonlinear and differ from ones in the advanced economies.

  1. Predicting transition to chronic pain

    PubMed Central

    Apkarian, A. Vania; Baliki, Marwan N.; Farmer, Melissa A.

    2016-01-01

    Purpose of review Most individuals who develop pain following an inciting event will return to a healthy state as the injury heals. However, a small percentage continue to suffer, that is, transition to chronic pain. Chronic pain may persist for years and is accompanied by cognitive abnormalities, as well as diminished quality of life. In animals, persistent pain is characterized by peripheral and spinal cord reorganization, and recent evidence in humans also indicates cortical reorganization. Yet, despite more than 30 years of research, there is little agreement on the neural mechanisms that mediate the transition from acute to chronic pain. Recent findings In a longitudinal brain-imaging study, individuals who developed an intense back pain episode were followed over a 1-year period, during which pain and brain parameters were collected repeatedly. A smaller number of healthy individuals and chronic back pain patients were also studied concomitantly, as positive and negative controls. At the time of entry into the study, strength of synchrony between the medial prefrontal cortex and nucleus accumbens (i.e. functional connectivity) was predictive (>80% accuracy) of individuals who subsequently transition to chronicity 1 year later. Summary Properties of the brain’s emotional learning circuitry predict the transition to chronic pain. The involvement of this circuitry in pain remains mostly unexplored. Future human and animal model studies are necessary to unravel underlying mechanisms driving pain chronicity, with the potential of advancing novel therapeutics for preventing pain chronification. PMID:23823463

  2. On Comparing Transition Rate Gains.

    ERIC Educational Resources Information Center

    Reuterberg, Sven-Eric

    This report is about the problem of making transition or enrollment rate gains comparable. It is shown that measures based on the proportions themselves, i.e. the difference between proportions, the proportion ratio and the residual gain ratio do not make the gains comparable. Instead a non-linear transformation has to be done. Two such…

  3. Suicide and Mass Urban Transit.

    ERIC Educational Resources Information Center

    Berman, Alan L., Ed.

    1991-01-01

    Presents case consultation in which consultants respond to issues of urban planning for mass transit (subway) system and how to maximize prevention of intentional injury within subway stations. Also asks what type of research study should be used and what type of data collected once system is operating. Case is discussed by Morton M. Silverman and…

  4. Understanding Student Veterans in Transition

    ERIC Educational Resources Information Center

    Jones, Kevin C.

    2013-01-01

    In this research report the author details a phenomenological study documenting identity development in student veterans making the transition from active military service to higher education. This study took place at a doctoral granting proprietary university with a significant veteran population and consisted of in-depth interviews. This…

  5. The nature of transition blazars

    SciTech Connect

    Ruan, J. J.; Anderson, S. F.; Plotkin, R. M.; Brandt, W. N.; Schneider, D. P.; Burnett, T. H.; Myers, A. D.

    2014-12-10

    Blazars are classically divided into the BL Lacertae (BLL) and flat-spectrum radio quasar (FSRQ) subclasses, corresponding to radiatively inefficient and efficient accretion regimes, respectively, largely based on the equivalent width (EW) of their optical broad emission lines (BELs). However, EW-based classification criteria are not physically motivated, and a few blazars have previously transitioned' from one subclass to the other. We present the first systematic search for these transition blazars in a sample of 602 unique pairs of repeat spectra of 354 blazars in the Sloan Digital Sky Survey, finding six clear cases. These transition blazars have bolometric Eddington ratios of ∼0.3 and low-frequency synchrotron peaks, and are thus FSRQ-like. We show that the strong EW variability (up to an unprecedented factor of >60) is due to swamping of the BELs from variability in jet continuum emission, which is stronger in amplitude and shorter in timescale than typical blazars. Although these transition blazars appear to switch between FSRQ and BLL according to the phenomenologically based EW scheme, we show that they are most likely rare cases of FSRQs with radiatively efficient accretion flows and especially strongly beamed jets. These results have implications for the decrease of the apparent BLL population at high redshifts, and may lend credence to claims of a negative BLL redshift evolution.

  6. Leadership Transitions during Fundraising Campaigns

    ERIC Educational Resources Information Center

    Nehls, Kimberly

    2012-01-01

    Capital campaigns are intense efforts to build the financial assets of an institution in a specified amount of time. This study provides an empirical view of how changes in leadership affected concomitant capital campaigns at ten colleges and universities. The transitions during these 10 campaigns influenced morale on campus, altered timing of the…

  7. Quantifying macromolecular conformational transition pathways

    NASA Astrophysics Data System (ADS)

    Seyler, Sean; Kumar, Avishek; Thorpe, Michael; Beckstein, Oliver

    2015-03-01

    Diverse classes of proteins function through large-scale conformational changes that are challenging for computer simulations. A range of fast path-sampling techniques have been used to generate transitions, but it has been difficult to compare paths from (and assess the relative strengths of) different methods. We introduce a comprehensive method (pathway similarity analysis, PSA) for quantitatively characterizing and comparing macromolecular pathways. The Hausdorff and Fréchet metrics (known from computational geometry) are used to quantify the degree of similarity between polygonal curves in configuration space. A strength of PSA is its use of the full information available from the 3 N-dimensional configuration space trajectory without requiring additional specific knowledge about the system. We compare a sample of eleven different methods for the closed-to-open transitions of the apo enzyme adenylate kinase (AdK) and also apply PSA to an ensemble of 400 AdK trajectories produced by dynamic importance sampling MD and the Geometrical Pathways algorithm. We discuss the method's potential to enhance our understanding of transition path sampling methods, validate them, and help guide future research toward deeper physical insights into conformational transitions.

  8. Authority Work for Transitional Catalogs.

    ERIC Educational Resources Information Center

    Matters, Marion

    1990-01-01

    Discusses authority work and authority control for personal names and corporate bodies in transitional archive catalogs. The importance of conformance with standards so that archival materials will collocate with other types of material in integrated catalogs is also discussed, together with enhanced authority work and techniques for archival…

  9. Transition metal sulfide loaded catalyst

    DOEpatents

    Maroni, Victor A.; Iton, Lennox E.; Pasterczyk, James W.; Winterer, Markus; Krause, Theodore R.

    1994-01-01

    A zeolite based catalyst for activation and conversion of methane. A zeolite support includes a transition metal (Mo, Cr or W) sulfide disposed within the micropores of the zeolite. The catalyst allows activation and conversion of methane to C.sub.2 + hydrocarbons in a reducing atmosphere, thereby avoiding formation of oxides of carbon.

  10. Universities in Transition in Asia.

    ERIC Educational Resources Information Center

    Gungwu, Wang

    1992-01-01

    Discusses the history of Asian universities, their position today, and what the transitions represent for the future. Describes the major debate in the past as concerning the preservation of traditional cultural values while becoming modern institutions. Argues that Asian universities need to recognize the great relevance of traditions to social…

  11. Flexible Scheduling: Making the Transition

    ERIC Educational Resources Information Center

    Creighton, Peggy Milam

    2008-01-01

    Citing literature that supports the benefits of flexible scheduling on student achievement, the author exhorts readers to campaign for flexible scheduling in their library media centers. She suggests tips drawn from the work of Graziano (2002), McGregor (2006) and Stripling (1997) for making a smooth transition from fixed to flexible scheduling:…

  12. Preterm Birth: Transition to Adulthood

    ERIC Educational Resources Information Center

    Allen, Marilee C.; Cristofalo, Elizabeth; Kim, Christina

    2010-01-01

    Preterm birth is associated with greater difficulty with transitions from childhood to adolescence to adulthood. Adolescents and young adults born preterm have higher rates of cerebral palsy, intellectual disability, cognitive impairment, learning disability, executive dysfunction, attention deficit disorder, and social-emotional difficulties than…

  13. Person-Centered Transition Planning.

    ERIC Educational Resources Information Center

    Miner, Craig A.; Bates, Paul E.

    1997-01-01

    Describes a person-centered planning approach for involving students with disabilities and their families in the transition planning process. Components of person-centered planning are discussed, including development of a personal profile, identification of future lifestyle preferences, action steps and responsible parties, and necessary changes…

  14. Alternative Assessment for Transitional Readers.

    ERIC Educational Resources Information Center

    Beaumont, Carol; de Valenzuela, Julia Scherba; Trumbull, Elise

    2002-01-01

    A teacher-developed alternative assessment of reading comprehension was specifically designed for transitional English language learners. Use of the measure with 89 fifth-graders in their first year of English language instruction showed that the students could successfully engage with English texts and provided teachers with useful information to…

  15. GLOBAL TRANSITION TO SUSTAINABLE DEVELOPMENT

    EPA Science Inventory

    Global transition to sustainable development is possible but many obstacles lie in the way and it will require acts of political will on the part of both the developed and developing nations to become a reality. In this paper, sustainable development is defined as continuous prog...

  16. Gifted Students' Transition to University

    ERIC Educational Resources Information Center

    Mendaglio, Sal

    2013-01-01

    The transition from school to university presents novel demands for all students. Although this educational milestone has been addressed by scholars, particularly those interested in the study of higher education, there is a dearth of literature regarding gifted students' experience of their handling demands of first-year university. In the…

  17. Dynamics of the chiral transition

    SciTech Connect

    Gavin, S.

    1994-07-01

    Measurements of disoriented chiral condensates (DCC) in heavy ion collisions at RHIC can yield fundamental information on the nature of the QCD phase transition. I review theoretical efforts to understand DCC formation and present work in progress on possible experimental ramifications.

  18. Dynamics of the chiral transition

    SciTech Connect

    Gavin, S.

    1995-07-10

    Measurements of disoriented chiral condensates (DCC) in heavy ion collisions at RHIC can yield fundamental information on the nature of the QCD phase transition. I review theoretical efforts to understand DCC formation and present work in progress on their possible experimental ramifications. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  19. Adolescent Urology and Transitional Care.

    PubMed

    Woodhouse, Christopher

    2015-11-01

    Babies with the major congenital anomalies of the genito-urinary tract have all-embracing holistic care during childhood. They require the same level of care in adult life. This is the role of transition and adolescent urology. PMID:26153563

  20. Narratives about Labour Market Transitions

    ERIC Educational Resources Information Center

    Cort, Pia; Thomsen, Rie

    2014-01-01

    In European Union policy, Denmark is often referred to as a model country in terms of its flexicurity model and provision of financial support and access to education and training during periods of unemployment, i.e. during transitional phases in a working life. However, in the research on flexicurity and its implications for labour market…

  1. Comparative Habitability of Transiting Exoplanets

    NASA Astrophysics Data System (ADS)

    Barnes, Rory; Meadows, Victoria S.; Evans, Nicole

    2015-12-01

    Exoplanet habitability is traditionally assessed by comparing a planet’s semimajor axis to the location of its host star’s “habitable zone,” the shell around a star for which Earth-like planets can possess liquid surface water. The Kepler space telescope has discovered numerous planet candidates near the habitable zone, and many more are expected from missions such as K2, TESS, and PLATO. These candidates often require significant follow-up observations for validation, so prioritizing planets for habitability from transit data has become an important aspect of the search for life in the universe. We propose a method to compare transiting planets for their potential to support life based on transit data, stellar properties and previously reported limits on planetary emitted flux. For a planet in radiative equilibrium, the emitted flux increases with eccentricity, but decreases with albedo. As these parameters are often unconstrained, there is an “eccentricity-albedo degeneracy” for the habitability of transiting exoplanets. Our method mitigates this degeneracy, includes a penalty for large-radius planets, uses terrestrial mass-radius relationships, and, when available, constraints on eccentricity to compute a number we call the “habitability index for transiting exoplanets” that represents the relative probability that an exoplanet could support liquid surface water. We calculate it for Kepler objects of interest and find that planets that receive between 60% and 90% of the Earth’s incident radiation, assuming circular orbits, are most likely to be habitable. Finally, we make predictions for the upcoming TESS and James Webb Space Telescope missions.

  2. The nature of structure and bonding between transition metal and mixed Si-Ge tetramers: A 20-electron superatom system.

    PubMed

    Li, Xiaojun; Yan, Zhijun; Li, Shuna

    2016-09-30

    A novel superatom species with 20-electron system, Six Gey M(+) (x + y = 4; M = Nb, Ta), was properly proposed. The trigonal bipyramid structures for the studied systems were identified as the putative global minimum by means of the density functional theory calculations. The high chemical stability can be explained by the strong p-d hybridization between transition metal and mixed Si-Ge tetramers, and closed-shell valence electron configuration [1S(2) 1P(6) 2S(2) 1D(10) ]. Meanwhile, the chemical bondings between metal atom and the tetramers can be recognized by three localized two-center two-electron (2c-2e) and delocalized 3c-2e σ-bonds. For all the doped structures studied here, it was found that the π- and σ-electrons satisfy the 2(N + 1)(2) counting rule, and thus these clusters possess spherically double (π and σ) aromaticity, which is also confirmed by the negative nucleus-independent chemical shifts values. Consequently, all the calculated results provide a further understanding for structural stabilities and electronic properties of transition metal-doped semiconductor clusters. © 2016 Wiley Periodicals, Inc. PMID:27452479

  3. The dimensionality of ammonium reorientation in (NH4)2S2O8: the view from neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Prager, M.; Grimm, H.; Natkaniec, I.; Nowak, D.; Unruh, T.

    2008-03-01

    The dynamics of the ammonium ion in ammonium persulfate is studied by inelastic neutron scattering at energy transfers between 0.7 µeV and about 100 meV. NH4+ librational modes are clearly split into four energetically different bands, in agreement with the absence of symmetry at the ammonium site. One strong, one medium and two weak hydrogen bonds from the NH4 ion to neighboring oxygens lead to this unusual potential shape with one dominating overlap matrix elements hi. Therefore the ammonium dynamics seen by neutron tunneling spectroscopy looks like a rotation about a single axis, that of the strongest hydrogen bond. Quasi-elastic scattering up to T = 100 K is dominated by jumps about this specific axis, too. Jumps about the second weak axis modify the quasi-elastic scattering at higher temperature. Results of a previous nuclear magnetic resonance (NMR) quadrupole resonance experiment are consistently interpreted to show the dynamics around the remaining two strong axes. The reduced isotope effect of the lowest librational band is due to a special shape of the potential and not to changes of the hydrogen bond with deuteration.

  4. Materials Data on NiH4C2(S2N)2 (SG:14) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  5. Materials Data on MgH8C2S2(NO2)2 (SG:14) by Materials Project

    DOE Data Explorer

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  6. Crystal structure of (2S/2R,3S/3R)-3-hydroxy-2-phenyl-chroman-4-one.

    PubMed

    Belguedj, Roumaissa; Bouacida, Sofiane; Merazig, Hocine; Chibani, Aissa; Bouraiou, Abdelmalek

    2015-02-01

    In the title mol-ecule, C15H12O3, the C atoms bearing the hy-droxy group and the phenyl ring are disordered over two sets of sites with refined occupancies of 0.573 (7) and 0.427 (7). There is also disorder of the phenyl ring but the hy-droxy group was refined as ordered. The dihedral angles between the benzene ring of the chromane ring system and the phenyl ring are 89.7 (2)° for the major component of disorder and 72.1 (3)° for the minor component. Both disorder components of the the di-hydro-pyran ring are in a half-chair conformation. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(10) graph-set motif. Weak C-H⋯π inter-actions link these dimers into ladders along [001]. PMID:25878868

  7. Understanding topological phase transition in monolayer transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Choe, Duk-Hyun; Sung, Ha-Jun; Chang, K. J.

    2016-03-01

    Despite considerable interest in layered transition metal dichalcogenides (TMDs), such as M X2 with M =(Mo ,W ) and X =(S ,Se ,Te ) , the physical origin of their topological nature is still poorly understood. In the conventional view of topological phase transition (TPT), the nontrivial topology of electron bands in TMDs is caused by the band inversion between metal d - and chalcogen p -orbital bands where the former is pulled down below the latter. Here, we show that, in TMDs, the TPT is entirely different from the conventional speculation. In particular, M S2 and M S e2 exhibits the opposite behavior of TPT such that the chalcogen p -orbital band moves down below the metal d -orbital band. More interestingly, in M T e2 , the band inversion occurs between the metal d -orbital bands. Our findings cast doubts on the common view of TPT and provide clear guidelines for understanding the topological nature in new topological materials to be discovered.

  8. Composition of transiting and transiting-only super-Earths

    NASA Astrophysics Data System (ADS)

    Valencia, Diana

    2011-11-01

    The relatively recent detections of the first three transiting super-Earths mark the beginning of a subfield within exoplanets that is both fruitful and challenging. The first step into characterizing these objects is to infer their composition given the degenerate character of the problem. The calculations show that Kepler-10b has a composition between an Earth-like and a Mercury-like (enriched in iron) composition. In contrast, GJ 1214b is too large to be solid, and has to have a volatile envelope. Lastly, while three of the four reported mass estimates of CoRoT-7b allow for a rocky composition, one forbids it and can only be reconciled with significant amounts of water vapor. In addition to these three transiting low-mass planets, there are now more than one thousand Kepler planets with only measured radius. Even without a mass measurement (``transiting-only'') it is still possible to place constraints on the amount of volatile content of the highly-irradiated planets, as their envelopes, if present, are flared. Using Kepler-9d as an example, we estimate its water vapor, or hydrogen and helium content to be less than 50% or 0.1% by mass respectively.

  9. Transitions

    NASA Technical Reports Server (NTRS)

    2006-01-01

    26 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a variety of textures observed on a dust-covered plain in the Marte Valles region of Mars. Textural variations across the scene include: areas that are littered with small impact craters, a channel-like feature that is dominated by mounds of a variety of sizes, small ripples and/or ridges, and relatively smooth, unremarkable terrain. The contact between the cratered plain and the area dominated by mounds marks one of the banks along the edge of one of the shallow valleys of the Marte Valles system.

    Location near: 17.7oN, 175.0oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  10. Articulated transition duct in turbomachine

    DOEpatents

    Flanagan, James Scott; McMahan, Kevin Weston; LeBegue, Jeffrey Scott; Pentecost, Ronnie Ray

    2014-04-29

    Turbine systems are provided. A turbine system includes a transition duct comprising an inlet, an outlet, and a duct passage extending between the inlet and the outlet and defining a longitudinal axis, a radial axis, and a tangential axis. The outlet of the transition duct is offset from the inlet along the longitudinal axis and the tangential axis. The duct passage includes an upstream portion and a downstream portion. The upstream portion extends from the inlet between an inlet end and an aft end. The downstream portion extends from the outlet between an outlet end and a head end. The turbine system further includes a joint coupling the aft end of the upstream portion and the head end of the downstream portion together. The joint is configured to allow movement of the upstream portion and the downstream portion relative to each other about or along at least one axis.

  11. The transition regions of Capella

    NASA Technical Reports Server (NTRS)

    Linsky, Jeffrey L.; Wood, Brian E.; Judge, Philip; Brown, Alexander; Andrulis, Catherine; Ayers, Thomas R.

    1995-01-01

    We have used the Goddard High Resolution Spectrometer (GHRS) to observe the spectoscopic binary system Capella (G8 III + G1 III). Exposures with the G140L, G140M, G160M, G200M, and echelle gratings provide emission line profiles with unprecedented signal-to-noise and spectral resolving power (lambda/Delta-lambda) up to 92,000. Multi-Gaussin fits to the line profiles show that the hotter star contributes 60%-70% of the total flux in the chromospheric O I and Mg II resonance lines, but about 90% of the flux in the Si III, Si IV, and C IV lines formed in the transition region at T less than or = 10(exp 5) K. We find clear evidence that the emission lines from the hotter star are systemtically redshifted relative to the photosphere with Doppler shifts of 5 +/- 1 km/s for the +9 +/- 3 km/s in the chromospheric Mg II and O I lines, respectively, increasing to +24 +/- 5 km/s for the transition region Si IV 1393.8A line. The multi-Gaussian fits to permitted transition region lines of SI III, Si IV, C IV, and N V indicate the presence of three components: moderately broad lines formed in the transition region of the hotter star (component H), narrow lines formed in the transition region of the cooler star (component C), and very broad lines that we think are formed in microflares on the hotter star (component B). The He II 1640.4 A feature has an broad profile, which indicates that it is formed by collisional excitation primarily from the hotter star, and a weak narrow component that we interpret as due to radiative recombination on the cooler star. We observed spin-forbidden emission lines of C III), O III), Si III), O IV), O V), and S IV) that are sensitive to electron density. Fainter members of the O IV) multiplet and all of the S IV) lines have never before been seen in any star than the Sun. We determine electron densities in the transition regions of the Capella stars using lines ratios of O IV) lines and emission measure analysis. The emission measures are self

  12. Holographic Roberge-Weiss transitions

    NASA Astrophysics Data System (ADS)

    Aarts, Gert; Kumar, S. Prem; Rafferty, James

    2010-07-01

    We investigate mathcal{N} = 4 SYM coupled to fundamental flavours at nonzero imaginary quark chemical potential in the strong coupling and large N limit, using gauge/gravity duality applied to the D3-D7 system, treating flavours in the probe approximation. The interplay between {mathbb{Z}_N} symmetry and the imaginary chemical potential yields a series of first-order Roberge-Weiss transitions. An additional thermal transition separates phases where quarks are bound/ unbound into mesons. This results in a set of Roberge-Weiss endpoints: we establish that these are triple points, determine the Roberge-Weiss temperature, give the curvature of the phase boundaries and confirm that the theory is analytic in μ 2 when μ 2 ≈ 0.

  13. Electronic transitions of palladium dimer

    SciTech Connect

    Qian, Yue; Ng, Y. W.; Chen, Zhihua; Cheung, A. S.-C.

    2013-11-21

    The laser induced fluorescence spectrum of palladium dimer (Pd{sub 2}) in the visible region between 480 and 700 nm has been observed and analyzed. The gas-phase Pd{sub 2} molecule was produced by laser ablation of palladium metal rod. Eleven vibrational bands were observed and assigned to the [17.1] {sup 3}II{sub g} - X{sup 3}Σ{sub u}{sup +} transition system. The bond length (r{sub o}) and vibrational frequency (ΔG{sub 1/2}) of the ground X{sup 3}Σ{sub u}{sup +} state were determined to be 2.47(4) Å and 211.4(5) cm{sup −1}, respectively. A molecular orbital energy level diagram was used to understand the observed ground and excited electronic states. This is the first gas-phase experimental investigation of the electronic transitions of Pd{sub 2}.

  14. Venus transits - A French view

    NASA Astrophysics Data System (ADS)

    Débarbat, Suzanne

    2005-04-01

    After a careful study of Mars observations obtained by Tycho Brahé (1546-1601), Kepler (1571-1630) discovered the now-called Kepler's third law. In 1627 he published his famous Tabulae Rudolphinae, a homage to his protector Rudolph II (1552-1612), tables (Kepler 1609, 1627) from which he predicted Mercury and Venus transits over the Sun. In 1629 Kepler published his Admonitio ad Astronomos Advertisement to Astronomers (Kepler 1630), Avertissement aux Astronomes in French Au sujet de phénomènes rares et étonnants de l'an 1631: l'incursion de Vénus et de Mercure sur le Soleil. This was the beginning of the interest of French astronomers, among many others, in such transits, mostly for Venus, the subject of this paper in which dates are given in the Gregorian calendar.

  15. Unified transition path and universal transition state for ZB to RS or WZ to RS high pressure phase transition

    NASA Astrophysics Data System (ADS)

    Miao, Maosheng

    2005-07-01

    We show that the previously proposed transition paths for high pressure phase transitions for semiconductor from zinc blende (ZB) to rocksalt (RS) and from wurtzite (WZ) to rocksalt can be unified and can be extended to transitions from various tetrahedrally bonded polytypes to rocksalt [1]. Our first principle pseudopotential calculations with density functional and constrained relaxation methods on SiC showed that the ZB to RS transition has the lowest transition barrier. Our calculations on ZB to RS transition path for other semiconductors including II-VI, III-V and group IV semiconductors, show that the position and the geometry of the transition state, the state that correspond to the transition barrier, are universal and do not depend on the chemical components of the system [2]. We also extended the Landau phase transition model to a ZB to RS transition by using a cosine function of the atom displacement as order parameter. The model shows that the position of the transition state does not depend on the coupling between the atom displacement and the strains of the lattice, which is the key point that the transition state is independent of the chemical components. [1] M. S. Miao and Walter R. L. Lambrecht, Phys. Rev. B 68, 092103 (2003). [2] M. S. Miao and Walter R. L. Lambrecht, Phys. Rev. Lett., accepted

  16. Relative transition probabilities of cobalt

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    Results of determinations of neutral-cobalt transition probabilities measured relative to Co I 4150.43 A and Co II 4145.15 A, using a gas-driven shock tube as the spectroscopic light source. Results are presented for 139 Co I lines in the range from 3940 to 6640 A and 11 Co II lines in the range from 3840 to 4730 A, which are estimated to have reliabilities ranging from 8 to 50%.

  17. Phase transitions in nuclear matter

    SciTech Connect

    Glendenning, N.K.

    1984-11-01

    The rather general circumstances under which a phase transition in hadronic matter at finite temperature to an abnormal phase in which baryon effective masses become small and in which copious baryon-antibaryon pairs appear is emphasized. A preview is also given of a soliton model of dense matter, in which at a density of about seven times nuclear density, matter ceases to be a color insulator and becomes increasingly color conducting. 22 references.

  18. Trust transitivity in social networks.

    PubMed

    Richters, Oliver; Peixoto, Tiago P

    2011-01-01

    Non-centralized recommendation-based decision making is a central feature of several social and technological processes, such as market dynamics, peer-to-peer file-sharing and the web of trust of digital certification. We investigate the properties of trust propagation on networks, based on a simple metric of trust transitivity. We investigate analytically the percolation properties of trust transitivity in random networks with arbitrary in/out-degree distributions, and compare with numerical realizations. We find that the existence of a non-zero fraction of absolute trust (i.e. entirely confident trust) is a requirement for the viability of global trust propagation in large systems: The average pair-wise trust is marked by a discontinuous transition at a specific fraction of absolute trust, below which it vanishes. Furthermore, we perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in view of the concepts introduced. We compare different scenarios of trust distribution: community- and authority-centered. We find that these scenarios lead to sharply different patterns of trust propagation, due to the segregation of authority hubs and densely-connected communities. While the authority-centered scenario is more efficient, and leads to higher average trust values, it favours weakly-connected "fringe" nodes, which are directly trusted by authorities. The community-centered scheme, on the other hand, favours nodes with intermediate in/out-degrees, in detriment of the authorities and its "fringe" peers. PMID:21483683

  19. Non-equilibrium phase transitions

    SciTech Connect

    Mottola, E.; Cooper, F.M.; Bishop, A.R.; Habib, S.; Kluger, Y.; Jensen, N.G.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Non-equilibrium phase transitions play a central role in a very broad range of scientific areas, ranging from nuclear, particle, and astrophysics to condensed matter physics and the material and biological sciences. The aim of this project was to explore the path to a deeper and more fundamental understanding of the common physical principles underlying the complex real time dynamics of phase transitions. The main emphasis was on the development of general theoretical tools to deal with non-equilibrium processes, and of numerical methods robust enough to capture the time-evolving structures that occur in actual experimental situations. Specific applications to Laboratory multidivisional efforts in relativistic heavy-ion physics (transition to a new phase of nuclear matter consisting of a quark-gluon plasma) and layered high-temperature superconductors (critical currents and flux flow at the National High Magnetic Field Laboratory) were undertaken.

  20. Dynamic transitions in dislocation motion

    NASA Astrophysics Data System (ADS)

    Bulatov, Vasily; Cai, Wei; Marian, Jaime

    2003-03-01

    In a series of Molecular Dynamics simulations, we observe that, depending on stress, temperature and line length, screw dislocations in BCC iron move in three strikingly different regimes. Under low stress, the dislocations move smoothly via formation and migration of atomic-sized kinks; although widely believed, such motion mechanism has never been directly observed in full dynamic detail. Then, at a higher stress, dislocation motion suddenly becomes rough: the line becomes rugged and its motion becomes jerky producing in its wake a large amount of debris in the form of lattice vacancies and interstitial clusters. Remarkably, this bizarre behavior is not caused by any external factors, such as dislocation interaction with other crystal defects: the roughening transition is intrinsic to the dislocation itself. Under increasing stress the line raggedness and the amount of debris its motion produces continue to increase until, at some point, another dynamic transition takes place. The dislocation is now seen to cease at once its turbulent motion through the lattice and to initiate a thin plate of sheared crystal, a twin. The twin plate picks up where the dislocation just left off - it extends very fast in the same direction as dislocation motion and increases, gradually, in thickness. Notably, no more debris is produced during the twinning motion. The origin of these dynamic transitions, the underlying atomistic mechanisms of dislocation motion in all three regimes and their implication for strength of shocked materials are discussed.

  1. Major transitions in information technology.

    PubMed

    Valverde, Sergi

    2016-08-19

    When looking at the history of technology, we can see that all inventions are not of equal importance. Only a few technologies have the potential to start a new branching series (specifically, by increasing diversity), have a lasting impact in human life and ultimately became turning points. Technological transitions correspond to times and places in the past when a large number of novel artefact forms or behaviours appeared together or in rapid succession. Why does that happen? Is technological change continuous and gradual or does it occur in sudden leaps and bounds? The evolution of information technology (IT) allows for a quantitative and theoretical approach to technological transitions. The value of information systems experiences sudden changes (i) when we learn how to use this technology, (ii) when we accumulate a large amount of information, and (iii) when communities of practice create and exchange free information. The coexistence between gradual improvements and discontinuous technological change is a consequence of the asymmetric relationship between complexity and hardware and software. Using a cultural evolution approach, we suggest that sudden changes in the organization of ITs depend on the high costs of maintaining and transmitting reliable information.This article is part of the themed issue 'The major synthetic evolutionary transitions'. PMID:27431527

  2. Saturn as a Transiting Exoplanet

    NASA Astrophysics Data System (ADS)

    Dalba, Paul A.; Muirhead, Philip S.; Fortney, Jonathan J.; Hedman, Matthew M.; Nicholson, Philip D.; Veyette, Mark J.

    2015-11-01

    Previous investigations of exoplanet atmospheres have not targeted those resembling the gas giant planets in our solar system. These types of exoplanets are too cold to be directly imaged or observed in emission, and their low transit probabilities and frequencies make characterization via transmission spectroscopy a challenging endeavor. However, studies of cold giant exoplanets would be highly valuable to our understanding of planet formation and migration and could place the gas giant members of our own solar system in a greater context. Here, we use solar occultations observed by the Visual and Infrared Mapping Spectrometer aboard the Cassini Spacecraft to extract the 1 to 5 μm transmission spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption features from several molecules despite the presence of ammonia clouds. Self-consistent exoplanet atmosphere models show good agreement with Saturn's transmission spectrum but fail to reproduce the largest feature in the spectrum. We also find that atmospheric refraction determines the minimum altitude that could be probed during mid-transit of a Saturn-twin exoplanet around a Sun-like star. These results suggest that transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories.

  3. Trust Transitivity in Social Networks

    PubMed Central

    Richters, Oliver; Peixoto, Tiago P.

    2011-01-01

    Non-centralized recommendation-based decision making is a central feature of several social and technological processes, such as market dynamics, peer-to-peer file-sharing and the web of trust of digital certification. We investigate the properties of trust propagation on networks, based on a simple metric of trust transitivity. We investigate analytically the percolation properties of trust transitivity in random networks with arbitrary in/out-degree distributions, and compare with numerical realizations. We find that the existence of a non-zero fraction of absolute trust (i.e. entirely confident trust) is a requirement for the viability of global trust propagation in large systems: The average pair-wise trust is marked by a discontinuous transition at a specific fraction of absolute trust, below which it vanishes. Furthermore, we perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in view of the concepts introduced. We compare different scenarios of trust distribution: community- and authority-centered. We find that these scenarios lead to sharply different patterns of trust propagation, due to the segregation of authority hubs and densely-connected communities. While the authority-centered scenario is more efficient, and leads to higher average trust values, it favours weakly-connected “fringe” nodes, which are directly trusted by authorities. The community-centered scheme, on the other hand, favours nodes with intermediate in/out-degrees, in detriment of the authorities and its “fringe” peers. PMID:21483683

  4. Glass Transitions in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Meng, Dong; Kumar, Sanat

    2014-03-01

    For polymers are under geometric confinement, it is generally believed that the glass transition temperature (Tg) increases with favorable interfacial interactions. Experiments and simulations have reported that Tg increases almost proportionally to the attractive polymer-surface interactions. However, recent studies have reported the contradictory finding that the Tg shift is rather modest and insensitive to the strength of interfacial attractions. In this study, we investigate the glass transition in polymer nanocomposites using molecular dynamics simulations. With attractive polymer-nanoparticle (NP) interactions, we find that Tg is increased by ~ 3% at moderate loadings and that the shift stays almost unchanged when the polymer-NP attractions are further increased by one order of magnitude. Both are in agreement with the recent experiments at comparable NP loadings. We show that this is because the strongly adsorbed polymer segments do not participate in the glass transition. In other words, strong polymer-NP attractions create immobile polymer ``coatings'' around NPs that shield them from direct contact with the mobile polymers.

  5. Rehabilitation Counseling in Transition Planning and Preparation.

    ERIC Educational Resources Information Center

    Szymanski, Edna Mora; King, John

    1989-01-01

    The article addresses the role of rehabilitation counselors in special education transition programs for students with disabilities. It contends that the special training of rehabilitation counselors prepares them to coordinate existing school and community resources into effective transition programs. (DB)

  6. Nuclear physics: Elusive transition spotted in thorium

    NASA Astrophysics Data System (ADS)

    Safronova, Marianna

    2016-05-01

    The highly precise atomic clocks used in science and technology are based on electronic transitions in atoms. The discovery of a nuclear transition in thorium-229 raises hopes of making nuclear clocks a reality. See Article p.47

  7. Functions and Requirements for the Transition Project

    SciTech Connect

    YANOCHKO, R.M.

    2000-04-24

    This document describes the functional requirement baseline for the Transition of 100 K Area Facilities Project (Transition Project). This baseline information consists of top-level functions, requirements, concept description, interface description, issues, and enabling assumptions.

  8. The transit of Venus across the Sun

    NASA Astrophysics Data System (ADS)

    Simaan, Arkan

    2004-05-01

    This article explains the significance of a transit of Venus and relates scientists' efforts at making precise observations of transits over the past 250 years. JG was supported by KBN grant no 2 P03A 020 24.

  9. OBSERVATIONAL WINDOW FUNCTIONS IN PLANET TRANSIT SURVEYS

    SciTech Connect

    Von Braun, Kaspar; Kane, Stephen R.; Ciardi, David R. E-mail: skane@ipac.caltech.edu

    2009-09-01

    The probability that an existing planetary transit is detectable in one's data is sensitively dependent upon the window function of the observations. We quantitatively characterize and provide visualizations of the dependence of this probability as a function of orbital period upon several observing strategy and astrophysical parameters, such as length of observing run, observing cadence, length of night, transit duration and depth, and the minimum number of sampled transits. The ability to detect a transit is directly related to the intrinsic noise of the observations. In our simulations of observational window functions, we explicitly address noncorrelated (Gaussian or white) noise and correlated (red) noise and discuss how these two noise components affect transit detectability in fundamentally different manners, especially for long periods and/or small transit depths. We furthermore discuss the consequence of competing effects on transit detectability, elaborate on measures of observing strategies, and examine the projected efficiency of different transit survey scenarios with respect to certain regions of parameter space.

  10. Polarized gravitational waves from cosmological phase transitions

    NASA Astrophysics Data System (ADS)

    Kisslinger, Leonard; Kahniashvili, Tina

    2015-08-01

    We estimate the degree of circular polarization for the gravitational waves generated during the electroweak and QCD phase transitions from the kinetic and magnetic helicity generated by bubble collisions during those cosmological phase transitions.

  11. Fast flux test facility, transition project plan

    SciTech Connect

    Guttenberg, S.

    1994-11-15

    The FFTF Transition Project Plan, Revision 1, provides changes and project baseline for the deactivation activities necessary to transition the FFTF to a radiologically and industrially safe shutdown condition.

  12. Isoconversion Analysis of the Glass Transition

    NASA Astrophysics Data System (ADS)

    Badrinarayanan, Prashanth; Zheng, Wei; Simon, Sindee

    2007-03-01

    At temperatures below their glass transition temperatures (Tgs), glass forming materials deviate from equilibrium density and form a glass. The kinetic nature of the glass transition process is manifested in the cooling rate dependence of the glass transition temperature and by structural relaxation below Tg. Various facets of the glass transition kinetics have been well described by phenomenological models of the glass transition, such as the TNM and KAHR model. An important yet frequently questioned assumption in these models is that the apparent activation energy, which describes the temperature dependence of the relaxation time, does not vary during the glass transition process. Some recent reports suggest that the activation energy varies significantly during the glass transition process. In this work we apply an isoconversion analysis to data in the glass transition region which was obtained on cooling from capillary dilatometry and differential scanning calorimetry (DSC) in order to determine whether the apparent activation energy increases as the glassy state is approached.

  13. Phase transition dynamics and gravitational waves

    SciTech Connect

    Megevand, Ariel

    2009-04-20

    During a first-order phase transition, gravitational radiation is generated either by bubble collisions or by turbulence. For phase transitions which took place at the electroweak scale and beyond, the signal is expected to be within the sensitivity range of planned interferometers such as LISA or BBO. We review the generation of gravitational waves in a first-order phase transition and discuss the dependence of the spectrum on the dynamics of the phase transition.

  14. Planets in Transit V Passages of Discovery

    NASA Astrophysics Data System (ADS)

    Castellano, T. P.

    2003-05-01

    Eclipses of the Sun have long influenced culture, history, and science. The analogous but much more subtle phenomena of a transit of the Sun by Mercury was first predicted by Johannes Kepler. Soon, predictions of transits of Venus inspired bold expeditions to better understand the scale of our solar system. These passages of discovery sometimes succeeded scientifically but always captured the public imagination and played an unexpected role in history. The possibility of detecting planets outside the solar system by the transit method was first outlined by Otto Struve in 1952. Early inquiries usually assumed that extrasolar planetary systems would have a distribution of planetary radii and orbital sizes like the solar system. The detection of transits from the ground in such systems would be daunting. The recent, unexpected discovery of a class of extrasolar planets (by the radial velocity technique) with orbital periods less than a week and masses near to the planet Jupiter has resulted in a resurgence of interest in the transit method. These so called "hot Jupiters", can produce transits that are likely enough, frequent enough, the transit method. These so called "hot Jupiters", can produce transits that are likely enough, frequent enough, and deep enough that ground-based transit searches can be successful. In November 1999, a planet orbiting the star HD 209458 was found to transit, and many measurements of the transit have since been made that challenge formation and evolution theories. Numerous ground based searches for transits are now underway. Several planned high precision space-based missions designed to detect transits of earth-sized planets, also have the potential to detect transits of hundreds of "hot Jupiters". These efforts and the upcoming transit of the Sun by Venus on June 8, 2004 present an opportunity for transits to once again capture the public imagination and perhaps play a role in history.

  15. Microscopic Description of Nuclear Quantum Phase Transitions

    SciTech Connect

    Niksic, T.; Vretenar, D.; Lalazissis, G. A.; Ring, P.

    2007-08-31

    The relativistic mean-field framework, extended to include correlations related to restoration of broken symmetries and to fluctuations of the quadrupole deformation, is applied to a study of shape transitions in Nd isotopes. It is demonstrated that the microscopic self-consistent approach, based on global effective interactions, can describe not only general features of transitions between spherical and deformed nuclei, but also the singular properties of excitation spectra and transition rates at the critical point of quantum shape phase transition.

  16. Spin reorientation transition of magnetite (001)

    NASA Astrophysics Data System (ADS)

    Martín-García, Laura; Mascaraque, Arantzazu; Pabón, Beatriz M.; Bliem, Roland; Parkinson, Gareth S.; Chen, Gong; Schmid, Andreas K.; de la Figuera, Juan

    2016-04-01

    We have imaged the rearrangement of the magnetic domains on magnetite (001) when crossing the spin reorientation transition and the Verwey transition with nanometer resolution. By means of spin-polarized low-energy electron microscopy we have monitored the change in the easy axes lowering the temperature through both transitions in remanence. The spin reorientation transition occurs in two steps: initial nucleation and growth of domains with a new surface magnetic orientation is followed by a smooth evolution.

  17. 33 CFR 401.74 - Transit declaration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Transit declaration. 401.74 Section 401.74 Navigation and Navigable Waters SAINT LAWRENCE SEAWAY DEVELOPMENT CORPORATION, DEPARTMENT OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Toll Assessment and Payment § 401.74 Transit declaration. (a) Seaway Transit...

  18. Research Results from the Student Transitions Project

    ERIC Educational Resources Information Center

    Ministry of Advanced Education and Labour Market Development, 2007

    2007-01-01

    This report highlights student transition trends across a four-year period, with K-12 data from 2001/02 - 2004/05 and post-secondary data from 2002/03-2005/06. Reported findings include: (1) There is a consistent trend in immediate entry transition rates, with slightly more than half of all high school graduates making an immediate transition into…

  19. 15 CFR 8a.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Transition plans. 8a.230 Section 8a... Transition plans. (a) Submission of plans. An institution to which § 8a.225 applies and that is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  20. 45 CFR 86.17 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 1 2011-10-01 2011-10-01 false Transition plans. 86.17 Section 86.17 Public... Transition plans. (a) Submission of plans. An institution to which § 86.16 applies and which is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  1. 45 CFR 618.230 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false Transition plans. 618.230 Section 618.230 Public... Coverage § 618.230 Transition plans. (a) Submission of plans. An institution to which § 618.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  2. 24 CFR 3.230 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 24 Housing and Urban Development 1 2014-04-01 2014-04-01 false Transition plans. 3.230 Section 3... Coverage § 3.230 Transition plans. (a) Submission of plans. An institution to which § 3.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  3. 38 CFR 23.230 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2013-07-01 2013-07-01 false Transition plans. 23.230... Coverage § 23.230 Transition plans. (a) Submission of plans. An institution to which § 23.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  4. 24 CFR 3.230 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 24 Housing and Urban Development 1 2013-04-01 2013-04-01 false Transition plans. 3.230 Section 3... Coverage § 3.230 Transition plans. (a) Submission of plans. An institution to which § 3.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  5. 24 CFR 3.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 1 2011-04-01 2011-04-01 false Transition plans. 3.230 Section 3... Coverage § 3.230 Transition plans. (a) Submission of plans. An institution to which § 3.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  6. 13 CFR 113.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Transition plans. 113.230 Section... Coverage § 113.230 Transition plans. (a) Submission of plans. An institution to which § 113.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  7. 31 CFR 28.230 - Transition plans.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false Transition plans. 28.230 Section 28... Transition plans. (a) Submission of plans. An institution to which § 28.225 applies and that is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  8. 15 CFR 8a.230 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Transition plans. 8a.230 Section 8a... Transition plans. (a) Submission of plans. An institution to which § 8a.225 applies and that is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  9. 34 CFR 106.17 - Transition plans.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 34 Education 1 2014-07-01 2014-07-01 false Transition plans. 106.17 Section 106.17 Education... Coverage § 106.17 Transition plans. (a) Submission of plans. An institution to which § 106.16 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  10. 45 CFR 86.17 - Transition plans.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 1 2013-10-01 2013-10-01 false Transition plans. 86.17 Section 86.17 Public... Transition plans. (a) Submission of plans. An institution to which § 86.16 applies and which is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  11. 31 CFR 28.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false Transition plans. 28.230 Section 28... Transition plans. (a) Submission of plans. An institution to which § 28.225 applies and that is composed of more than one administratively separate unit may submit either a single transition plan applicable...

  12. 40 CFR 7.75 - Transition plan.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Transition plan. 7.75 Section 7.75... of Handicap § 7.75 Transition plan. If structural changes to facilities are necessary to make the program or activity accessible to handicapped persons, a recipient must prepare a transition plan....

  13. 45 CFR 618.230 - Transition plans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 3 2011-10-01 2011-10-01 false Transition plans. 618.230 Section 618.230 Public... Coverage § 618.230 Transition plans. (a) Submission of plans. An institution to which § 618.225 applies and... plan applicable to all such units, or a separate transition plan applicable to each such unit....

  14. 40 CFR 7.75 - Transition plan.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Transition plan. 7.75 Section 7.75... of Handicap § 7.75 Transition plan. If structural changes to facilities are necessary to make the program or activity accessible to handicapped persons, a recipient must prepare a transition plan....

  15. 40 CFR 7.75 - Transition plan.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Transition plan. 7.75 Section 7.75... of Handicap § 7.75 Transition plan. If structural changes to facilities are necessary to make the program or activity accessible to handicapped persons, a recipient must prepare a transition plan....

  16. 40 CFR 7.75 - Transition plan.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Transition plan. 7.75 Section 7.75... of Handicap § 7.75 Transition plan. If structural changes to facilities are necessary to make the program or activity accessible to handicapped persons, a recipient must prepare a transition plan....

  17. 9 CFR 332.12 - Transition grants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Transition grants. 332.12 Section 332... CARCASSES, MEAT, AND MEAT FOOD PRODUCTS § 332.12 Transition grants. (a) Transition grants are funds that a... grant must use grant funds to reimburse the training costs of one employee per each...

  18. 9 CFR 381.522 - Transition grants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Transition grants. 381.522 Section 381... Interstate Shipment of Poultry Products § 381.522 Transition grants. (a) Transition grants are funds that a... grant must use grant funds to reimburse the training costs of one employee per each...

  19. 9 CFR 381.522 - Transition grants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Transition grants. 381.522 Section 381... Interstate Shipment of Poultry Products § 381.522 Transition grants. (a) Transition grants are funds that a... grant must use grant funds to reimburse the training costs of one employee per each...

  20. 9 CFR 332.12 - Transition grants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Transition grants. 332.12 Section 332... CARCASSES, MEAT, AND MEAT FOOD PRODUCTS § 332.12 Transition grants. (a) Transition grants are funds that a... grant must use grant funds to reimburse the training costs of one employee per each...

  1. 33 CFR 401.89 - Transit refused.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Transit refused. 401.89 Section... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations General § 401.89 Transit refused. (a) An officer may refuse to allow a vessel to transit when, (1) The vessel is not equipped in accordance with §§ 401.5...

  2. 33 CFR 401.89 - Transit refused.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Transit refused. 401.89 Section... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations General § 401.89 Transit refused. (a) An officer may refuse to allow a vessel to transit when, (1) The vessel is not equipped in accordance with §§ 401.5...

  3. On transit time instability in liquid jets

    NASA Technical Reports Server (NTRS)

    Grabitz, G.; Meier, G.

    1982-01-01

    A basic transit time instability in flows with disturbances of speed is found. It was shown that the mass distribution is established by and large by the described transit time effects. These transit time effects may also be involved for gas jets.

  4. 33 CFR 401.89 - Transit refused.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Transit refused. 401.89 Section... TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations General § 401.89 Transit refused. (a) An officer may refuse to allow a vessel to transit when, (1) The vessel is not equipped in accordance with §§ 401.5...

  5. Transition Problems and Play as Transitory Activity

    ERIC Educational Resources Information Center

    Brostrom, Stig

    2005-01-01

    Because too many children experience the transition to school as a culture shock, during the past decade teachers have implemented so-called transition activities in order to bridge the gap between preschool and school. However, transition to school also calls for a development of higher mental functions, among others the development of children's…

  6. Lost in Transition? Student Food Consumption

    ERIC Educational Resources Information Center

    Blichfeldt, Bodil Stilling; Gram, Malene

    2013-01-01

    Findings from transition studies as well as studies of student food show that the transition from living at home to independent living influences student food consumption and that food consumption might be problematic during this period. Furthermore, both students' enactment of being in transition and the food habits and practices they bring with…

  7. The Transition Experiences of Successful Chinese Immigrants

    ERIC Educational Resources Information Center

    Amundson, Norman E.; Yeung, Thomas; Sun, Iris; Chan, Keith; Cheng, Johnny

    2011-01-01

    This article focused on the transition experiences of 20 successful Chinese immigrants, in particular their transition stories and how they accounted for their success (what facilitated and hindered their transition). An enhanced critical incident method was used for data analysis. Four major success categories emerged: having a positive attitude…

  8. Electrical Dissipation Measurement of Polymer Phase Transitions

    NASA Technical Reports Server (NTRS)

    Long, E. R., R; Schuszler, A., II

    1983-01-01

    Technique measures solid/solid, glass/rubber, and liquid/liquid transition temperatures in polymers having dipole moments. Technique based on change in dipole packing that occurs with each transition and measured as change in electrical dissipation factor. Change in dipole packing occuring with each transition sensed by effect on dissipation factor.

  9. Phase Transition of Diluted Magnetic Semiconductor

    NASA Astrophysics Data System (ADS)

    Li, M. K.; Lee, S. J.; Yuldashev, S. U.; Ihm, G.; Kang, T. W.

    2011-12-01

    Three types of phase transitions in diluted magnetic semiconductor, first-order, second-order and mixed-order, are found in theory. Especially the mixed type transition shows two steps transition and novel specific heat property. Specific heat properties disclose a possible meta ferromagnetic phase confirmed by the experimental qualitative result.

  10. ASD Academic Transitions: Trends in Parental Perspective

    ERIC Educational Resources Information Center

    Lee, Cindy; McCoy, Kathleen M.; Zucker, Stanley H.; Mathur, Sarup R.

    2014-01-01

    Academic transitions are a necessary and important part of an ASD student's life. Parental involvement and perspective is a vital part of each transition planning process. The primary goal of this research was to identify trends in parent perspectives regarding ASD academic transitions through meta-synthesis of current research. The research…

  11. No Wasted Moments: Planning Purposeful Transitions

    ERIC Educational Resources Information Center

    Nicolucci, Sandra

    2010-01-01

    This article focuses on the nature of the "transitional minutes" in "any" music class. When transitional minutes before, during, and after rehearsals and classes are unplanned and left to chance, much viable and valuable teaching time is lost. When transitional minutes are well structured, learning can proceed efficiently. One tends to remember…

  12. Vulnerable Youth and Transitions to Adulthood

    ERIC Educational Resources Information Center

    Xie, Rongbing; Sen, Bisakha; Foster, E. Michael

    2014-01-01

    This chapter focuses on vulnerable youth, the challenges they face during their transitions to adulthood, and the adverse effects of limited support systems on those transitions. The authors offer recommendations on how adult educators can help facilitate smooth transitions into adulthood for vulnerable youth.

  13. 34 CFR 300.43 - Transition services.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Transition services. 300.43 Section 300.43 Education... DISABILITIES General Definitions Used in This Part § 300.43 Transition services. (a) Transition services means..., acquisition of daily living skills and provision of a functional vocational evaluation. (b)...

  14. 5 CFR 362.210 - Transition.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Transition. 362.210 Section 362.210... PROGRAM Program Administration § 362.210 Transition. OPM shall provide written guidance for the orderly transition of employees from the Presidential Management Intern Program to the Fellow program and may...

  15. Analysis of abrupt transitions in ecological systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The occurrence and causes of abrupt transitions, thresholds, or regime shifts between ecosystem states are of great concern and the likelihood of such transitions is increasing for many ecological systems. General understanding of abrupt transitions has been advanced by theory, but hindered by the l...

  16. A Latent Transition Model with Logistic Regression

    ERIC Educational Resources Information Center

    Chung, Hwan; Walls, Theodore A.; Park, Yousung

    2007-01-01

    Latent transition models increasingly include covariates that predict prevalence of latent classes at a given time or transition rates among classes over time. In many situations, the covariate of interest may be latent. This paper describes an approach for handling both manifest and latent covariates in a latent transition model. A Bayesian…

  17. School to Work: Making the Transition.

    ERIC Educational Resources Information Center

    Academy for Educational Development, Washington, DC. National Inst. for Work and Learning.

    This publication describes the Academy for Educational Development's (AED's) vision and work in school-to-work transition and related areas. School-to-work transition is defined, and components of a successful school-to-work transition system are listed. The National Institute for Work and Learning (NIWL) is currently conducting an extensive study…

  18. Magnetism and electronic phase transitions in monoclinic transition metal dichalcogenides with transition metal atoms embedded

    NASA Astrophysics Data System (ADS)

    Lin, Xianqing; Ni, Jun

    2016-08-01

    First-principles calculations have been performed to study the energetic, electronic, and magnetic properties of substitutional 3d transition metal dopants in monoclinic transition metal dichalcogenides (TMDs) as topological insulators ( 1 T ' - MX 2 with M = (Mo, W) and X = (S, Se)). We find various favorite features in these doped systems to introduce magnetism and other desirable electronic properties: (i) The Mn embedded monoclinic TMDs are magnetic, and the doped 1 T ' - MoS 2 still maintains the semiconducting character with high concentration of Mn, while an electronic phase transition occurs in other Mn doped monoclinic TMDs with an increasing concentration of Mn. Two Mn dopants prefer the ferromagnetic coupling except for substitution of the nearest Mo atoms in 1 T ' - MoS 2 , and the strength of exchange interaction shows anisotropic behavior with dopants along one Mo zigzag chain having much stronger coupling. (ii) The substitutional V is a promising hole dopant, which causes little change to the energy dispersion around the conduction and valence band edges in most systems. In contrast, parts of the conduction band drop for the electron dopants Co and Ni due to the large structural distortion. Moreover, closing band gaps of the host materials are observed with increasing carrier concentration. (iii) Single Fe dopant has a magnetic moment, but it also dopes electrons. When two Fe dopants have a small distance, the systems turn into nonmagnetic semiconductors. (iv) The formation energies of all dopants are much lower than those in hexagonal TMDs and are all negative in certain growth conditions, suggesting possible realization of the predicted magnetism, electronic phase transitions as well as carrier doping in 1 T ' - MX 2 based topological devices.

  19. Atomic data from the IRON Project. XXVIII. Electron excitation of the ^2P_(3/2) deg -> ^2P_(1/2) deg fine structure transition in fluorine-like ions at higher temperatures

    NASA Astrophysics Data System (ADS)

    Berrington, K. A.; Saraph, H. E.; Tully, J. A.

    1998-04-01

    The collision strength Omega(^2P_{3/2}^o , ^2P_{1/2}^o) for the fine structure transition within the ground term of 17 fluorine-like ions from Mg {sc iv} to Ni {sc xx} is calculated using the R-matrix method. We include target terms with n = 3 in order to take account of the resonance structure in Omega at energies above 2s2p^6^2 S. These resonances are delineated using a fine mesh of several thousand energy points to scan the region between the first and 27th excited terms. Results from an earlier calculation (IRON Project Paper IV) are used to cover the region below 2s2p^6 ^2S. We make use of the fact that Omega tends to the Born limit as the collision energy E \\to \\infty. The effective collision strength Upsilon is tabulated as a function of log T_s, where T_s = T/(Z - 8)^2 is a Z-scaled temperature. We compare results for Si^{+5}, Fe^{+17} and Ni^{+19} with those obtained by Mohan and co-workers. An explanation is given for the large discrepancy in the case of Upsilon(Si(+5) ).

  20. Work and quantum phase transitions: quantum latency.

    PubMed

    Mascarenhas, E; Bragança, H; Dorner, R; França Santos, M; Vedral, V; Modi, K; Goold, J

    2014-06-01

    We study the physics of quantum phase transitions from the perspective of nonequilibrium thermodynamics. For first-order quantum phase transitions, we find that the average work done per quench in crossing the critical point is discontinuous. This leads us to introduce the quantum latent work in analogy with the classical latent heat of first order classical phase transitions. For second order quantum phase transitions the irreversible work is closely related to the fidelity susceptibility for weak sudden quenches of the system Hamiltonian. We demonstrate our ideas with numerical simulations of first, second, and infinite order phase transitions in various spin chain models. PMID:25019721