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Sample records for isotope shift measurement

  1. Isotope shift measurements in titanium I

    NASA Astrophysics Data System (ADS)

    Azaroual, E. M.; Luc, P.; Vetter, R.

    1992-06-01

    The use of an effusive beam of titanium atoms crossed with a CW single-mode tunable dye laser has allowed the high-resolution, Doppler-free study of the isotope shifts between50Ti,48Ti and46Ti, for seven 3 d 2 4 s 2 a3 F J → 3 d 2 4 s 4 p z 5 D J , visible transitions of Ti I. The measurements show without ambiguity the existence of a non-negligible field shift. Using the values of the nuclear radii of titanium (coming from muonic X-ray measurements), it is possible to determine the respective values of the field and mass shifts.

  2. Measurement of isotope shifts in Fe II

    NASA Astrophysics Data System (ADS)

    Ascoli, Marco; Kawall, David; Eyler, Edward; Demille, David

    2006-05-01

    We describe absorption spectra of singly ionized iron (Fe II) obtained with a compact ion source and a high-resolution UV laser. Using a Nd:YAG laser ablation source and buffer gas cooling with room-temperature argon, Fe II ions are produced in a cold plasma. Grating spectroscopy is used to determine conditions favorable parameters providing good cooling and ion yield. This novel technique allows us to study the Fe II transition a ^6D9->z^6D^o9 with Doppler widths about 3 GHz, by measuring the absorption of a frequency-tripled pulse-amplified cw Ti:Sapphire laser. The isotope shift of this transition is important to the analysis of astronomical data on the cosmological evolution of the fine-structure constant α [1]. We will discus the design of the ion source and laser system, and present preliminary results. This study was funded by the National Science Foundation. 12 pt [1] J.K Webb,M.T. Murphy, V.V. Flambaum, V.A. Dzuba, J.D. Barrow, C.W. Churchill, J.X. Prochaska, and A.M. Wolfe, Phys. Rev. Lett. 87, 091301 (2001).

  3. Isotope shift and hyperfine structure measurements in titanium I

    NASA Astrophysics Data System (ADS)

    Luc, P.; Vetter, R.; Bauche-Arnoult, C.; Bauche, J.

    1994-09-01

    High accuracy measurements of hyperfine structure due to47Ti and49Ti in the 3 d 2 4 s 2 a 3 F 2-3 d 2 4 s4 p z 5 D 1 absorption line at σ=18482.772 cm-1 have been performed by use of a Doppler-free experiment, where a beam of titanium atoms is crossed by a CW single mode tunable dye laser. They have allowed for the determination of isotope shifts between46Ti,47Ti,48Ti,49Ti and50Ti. By use of accurate values of mean square nuclear charge radii for the even isotopes, it has been possible to separate mass shifts from field shifts and to determine accurate values for the mean square nuclear charge radii of47Ti and49Ti. The field shift presents a marked odd-even staggering.

  4. Measurement of hyperfine structure and isotope shifts in Gd II

    NASA Astrophysics Data System (ADS)

    Del Papa, Dylan F.; Rose, Christopher D. M.; Rosner, S. David; Holt, Richard A.

    2017-07-01

    We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the isotope shifts of 73 optical transitions in the wavelength range 421.5-455.8 nm and the hyperfine structures of 35 even parity and 33 odd parity levels in Gd II. Many of the isotope shifts and hyperfine structure measurements are the first for these transitions and levels. These atomic data can be used to correct for saturation and blending in the analysis of stellar spectra to determine chemical abundances. As a result, they have an important impact on studies of the history of nucleosynthesis in the Universe and on the use of photospheric abundance anomalies in Chemically Peculiar stars to infer indirect information about stellar interiors.

  5. Isotope shift measurements on the D1 line in francium isotopes at TRIUMF

    NASA Astrophysics Data System (ADS)

    Collister, R.; Tandecki, M.; Gwinner, G.; Behr, J. A.; Pearson, M. R.; Gomez, E.; Aubin, S.; Zhang, J.; Orozco, L. A.

    2013-05-01

    Francium is the heaviest alkali and has no stable isotopes. The longest-lived among them, with half-lives from seconds to a few minutes, are now available in the new Francium Trapping Facility at TRIUMF, Canada, for future weak interaction studies. We present isotope shift measurements on the 7S1 / 2 --> 7P1 / 2 (D 1) transition on three isotopes, 206, 207 and 213 in a magneto-optical trap. The shifts are measured using a c.w. Ti:sapphire laser locked to a stabilized cavity at the mid-point between two hyperfine transitions of the reference isotope 209Fr. Scanning tunable microwave sidebands locate transitions in the other isotopes. In combination with the D 2 isotope shifts, analysis can provide a separation of the field shift, due to a changing nuclear charge radius, and specific mass shift, due to changing electron correlations, in these isotopes. Work supported by NSERC and NRC from Canada, NSF and DOE from USA, CONYACT from Mexico.

  6. Homo- and Heteronuclear Multiple-Quantum Filters for Measurement of NMR Isotope Shifts

    NASA Astrophysics Data System (ADS)

    Wooten, E. W.; Dua, R. K.; Dotson, G. D.; Woodard, R. W.

    The measurement of NMR isotope shifts as mechanistic probes can be complicated by mixtures of isotopomers. Homo- and heteronuclear NMR techniques based on multiple-quantum filtration are presented and shown to be a useful aid in measuring such shifts. The effects of 1H/ 2H substitution and 16O/ 18O substitution on the nuclear shielding of 1H, 13C, and 31P in a multiply labeled phosphoenolpyruvate are measured and interpreted qualitatively in terms of their rovibrational origins.

  7. Isotope shifts of natural Sr+ measured by laser fluorescence in a sympathetically cooled Coulomb crystal

    NASA Astrophysics Data System (ADS)

    Dubost, B.; Dubessy, R.; Szymanski, B.; Guibal, S.; Likforman, J.-P.; Guidoni, L.

    2014-03-01

    We measured by laser spectroscopy the isotope shifts between naturally occurring even isotopes of strontium ions for both the 5s2S1/2→5p2P1/2 (violet) and the 4d2D3/2→5p2P1/2 (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing 103-104 laser-cooled Sr+ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom interacting with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the 5s2S1/2→5p2P1/2 transition are ν88-ν84=+378(4) MHz and ν88-ν86=+170(3) MHz, in agreement with previously reported measurements. In the case of the previously unexplored 4d2D3/2→5p2P1/2 transition we find ν88-ν84=-828(4) MHz and ν88-ν86=-402(2) MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of Sr+ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.

  8. A precise few-nucleon size difference by isotope shift measurements of helium

    NASA Astrophysics Data System (ADS)

    Rezaeian, Nima Hassan

    We perform high precision measurements of an isotope shift between the two stable isotopes of helium. We use laser excitation of the 23 S1 -- 23P0 transition at 1083 .... in a metastable beam of 3He and 4He atoms. A newly developed tunable laser frequency selector along with our previous electro-optic frequency modulation technique provides extremely reliable, adaptable, and precise frequency and intensity control. The intensity control contributes negligibly to overall experimental uncertainty by selecting (t selection < 50 ) and stabilizing the intensity of the required sideband and eliminating (˜10-5) the unwanted frequencies generated during the modulation of 1083 nm laser carrier frequency. The selection technique uses a MEMS based fiber switch (tswitch ≈ 10 ms) and several temperature stabilized narrow band (˜3 GHz) fiber gratings. A fiber based optical circulator and an inline fiber amplifier provide the desired isolation and the net gain for the selected frequency. Also rapid (˜2 sec.) alternating measurements of the 23 S1 -- 23P0 interval for both species of helium is achieved with a custom fiber laser for simultaneous optical pumping. A servo-controlled retro-reflected laser beam eliminates residual Doppler effects during the isotope shift measurement. An improved detection design and software control makes negligible subtle potential biases in the data collection. With these advances, combined with new internal and external consistency checks, we are able to obtain results consistent with the best previous measurements, but with substantially improved precision. Our measurement of the 23S 1 -- 23P0 isotope shift between 3He and 4He is 31 097 535.2 (5)kHz. The most recent theoretic calculation combined with this measuremen. yields a new determination for nuclear size differences between 3He and 4He: Deltarc = 0.292 6 (1)exp (8)th(52)expfm, with a precision of less than a part in 104 coming from the experimental uncertainty (first parenthesis), and a

  9. New lifetime measurements in the stable semimagic Sn isotopes using the Doppler-shift attenuation technique

    NASA Astrophysics Data System (ADS)

    Jungclaus, A.; Walker, J.; Leske, J.; Speidel, K.-H.; Stuchbery, A. E.; East, M.; Boutachkov, P.; Cederkäll, J.; Doornenbal, P.; Egido, J. L.; Ekström, A.; Gerl, J.; Gernhäuser, R.; Goel, N.; Górska, M.; Kojouharov, I.; Maier-Komor, P.; Modamio, V.; Naqvi, F.; Pietralla, N.; Pietri, S.; Prokopowicz, W.; Schaffner, H.; Schwengner, R.; Wollersheim, H.-J.

    2011-09-01

    Precise measurements of lifetimes in the picosecond range of excited states in the stable even-A Sn isotopes 112,114,116,122Sn have been performed using the Doppler shift attenuation technique. For the first excited 2+ states in 112Sn, 114Sn and 116Sn the E2 transition strengths deduced from the measured lifetimes are in disagreement with the previously adopted values. They indicate a shallow minimum at N = 66 in contrast to the maximum at mid-shell predicted by modern shell model calculations.

  10. Precision Measurement of the Hydrogen-Deuterium 1S-2S Isotope Shift

    SciTech Connect

    Parthey, Christian G.; Matveev, Arthur; Alnis, Janis; Pohl, Randolf; Udem, Thomas; Kolachevsky, Nikolai; Haensch, Theodor W.; Jentschura, Ulrich D.

    2010-06-11

    Measuring the hydrogen-deuterium isotope shift via two-photon spectroscopy of the 1S-2S transition, we obtain 670 994 334 606(15) Hz. This is a 10-times improvement over the previous best measurement [A. Huber et al., Phys. Rev. Lett. 80, 468 (1998)] confirming its frequency value. A calculation of the difference of the mean square charge radii of deuterium and hydrogen results in {sub d}-{sub p}=3.820 07(65) fm{sup 2}, a more than twofold improvement compared to the former value.

  11. Accurate measurements of transition frequencies and isotope shifts of laser-trapped francium.

    PubMed

    Sanguinetti, S; Calabrese, R; Corradi, L; Dainelli, A; Khanbekyan, A; Mariotti, E; de Mauro, C; Minguzzi, P; Moi, L; Stancari, G; Tomassetti, L; Veronesi, S

    2009-04-01

    An interferometric method is used to improve the accuracy of the 7S-7P transition frequencies of three francium isotopes by 1 order of magnitude. The deduced isotope shifts for 209-211Fr confirm the ISOLDE data. The frequency of the D2 transition of 212Fr--the accepted reference for all Fr isotope shifts--is revised, and a significant difference with the ISOLDE value is found. Our results will be a benchmark for the accuracy of the theory of Fr energy levels, a necessary step to investigate fundamental symmetries.

  12. Anharmonicity effects in impurity-vacancy centers in diamond revealed by isotopic shifts and optical measurements

    NASA Astrophysics Data System (ADS)

    Ekimov, E. A.; Krivobok, V. S.; Lyapin, S. G.; Sherin, P. S.; Gavva, V. A.; Kondrin, M. V.

    2017-03-01

    We studied isotopically enriched nano- and microdiamonds with optically active GeV- centers synthesized at high pressures and high temperatures in nonmetallic growth systems. The influence of isotopic composition on optical properties has been thoroughly investigated by photoluminescence-excitation (PLE) and photoluminescence (PL) spectroscopy to get insight into the nature and electronic structure of this color center. We have demonstrated that the large frequency defect (difference between oscillation frequencies in the ground and excited electronic states) does bring about large discrepancy between PLE and PL spectra and comparatively high isotopic shift of the zero phonon line. Both effects seem to be rather common to split-vacancy centers (for example SiV-), where the frequency defect reaches record high values. Isotopic substitution of carbon atoms in the diamond lattice results in even larger shifts, which are only partially accounted for by a redistribution of electron density caused by the volume change of the diamond lattice. It was shown that the vibronic frequency in this case does not depend on the mass of carbon atoms. The greatest part of this isotopic shift is due to anharmonicity effects, which constitute a substantial part of vibronic frequency observed in this center. The exact physical mechanism, which leads to significant enhancement of anharmonicity on substitution of 12C to 13C, is yet to be clarified.

  13. Applications of the two-photon doppler-free method: Hyperfine interactions and isotope shift measurements

    NASA Astrophysics Data System (ADS)

    Cagnac, B.

    1985-08-01

    The hyperfine structures are generally of the same order of magnitude as the Doppler broadening of optical transitions and so are the isotopic shifts in the case of heavy elements. When these structures are too small, one must use Doppler-free methods. Among these methods, the two-photon spectroscopy has obtained good results in highly excited levels. In our laboratory in Paris, we did measurements on neon and helium by two-photon excitation from metastable levels. The precision of the measurements is of the order of one MHz, which permits a precise comparison with theory. We compare the measurements on neon with the theory by Liberman and we obtain a good fit in the first approximation, but must introduce mixing of wave functions for an exact explanation. In the case of helium, we obtain a good fit with the theoretical values obtained from the wave functions by Accad, Pekeris and Schiff. We also give an example where another technique by polarization measurements permits us to obtain experimentally a hyperfine structure smaller than the natural width. We also present a short review of the measurements done by the two-photon method in other laboratories on other elements, Pb, Tl, In and alkaline earths Ca, Sr. Ba.

  14. Isotope shifts in francium isotopes Fr-213206 and 221Fr

    NASA Astrophysics Data System (ADS)

    Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L. A.; Aubin, S.; Gomez, E.; FrPNC Collaboration

    2014-11-01

    We present the isotope shifts of the 7 s1 /2 to 7 p1 /2 transition for francium isotopes 206 -213Fr with reference to 221Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7 s1 /2 to 7 p3 /2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D1 and D2 transitions, of sufficient precision to differentiate between ab initio calculations.

  15. Isotope shifts in methane near 6000/cm

    NASA Technical Reports Server (NTRS)

    Fox, K.; Halsey, G. W.; Jennings, D. E.

    1976-01-01

    Isotope shifts for cleanly resolved vibrational-rotational absorption lines of CH4-12 and CH4-13 were measured by a 5-m focal length Littrow spectrometer in the 6000/cm range. The methane isotopes were held in separate absorption cells: 20 torr of CH4-13 in a 1-m cell, and 5 torr of CH4-12 in a White cell of 4-m optical path length. Measured shifts for the cleanly resolved singlets R(0), R(1), Q(1) and P(1) are summarized in tabular form.

  16. Optical Spectroscopic Measurements of Isotope Shift and Hyperfine Structure in BISMUTH-207, BISMUTH-208 and LEAD-205.

    NASA Astrophysics Data System (ADS)

    Barboza Flores, Marcelino

    The isotope shift and hyperfine structure (hfs) of 38-yr ^{207}Bi and 3.7 times 10^5 -yr ^{208}Bi were measured, in the 6p^3 ^4S_ {1/2} - 6p^2 7s ^4P_{1/2} 306.7-nm resonance line, as well as the isotope shift of 1.4 times 10^7-yr ^ {205}Pb in the 6p^2 ^3P_0 - 6p7s ^3P_1 283.3-nm transition. A 9.1-m focal-length Czerny-Turner grating monochromator with a 25-cm wide diffraction grating (resolving power ~10^6) was used to obtain high resolution absorption spectra of an atomic vapor of lead and bismuth. The spectra were recorded photoelectrically using a signal-averaging spectrum scanning technique. The measured isotope shifts are IS(^ {207}Bi-^{209} Bi) = 0.0999(20) cm^{-1} , IS(^{208}Bi- ^{209}Bi) = 0.072(6) cm ^{-1} and IS(^ {205}Pb-^{208} Pb) = -123.9(2.0) times 10^{-3} cm ^{-1}. The derived magnetic dipole (A) and electric quadrupole (B) hfs interaction constants are A(^4P_{1/2})= 0.1630(3) cm^{-1}, B( ^4S_{3/2}) = -0.016(3) cm^{-1} for ^{207}Bi and A( ^4P_{1/2}) = 0.1639(20) cm^{-1} for ^ {208}Bi. The nuclear magnetic dipole (mu) and electric quadrupole moment (Q) were found to be mu(^{207 }Bi) = 4.051(7)mu_{N }, Q(^{207}Bi) = -0.60(11)b and mu(^ {208}Bi) = 4.52(6)mu_ {N}. The magnetic dipole moments agree with theoretical predictions based on the nuclear shell model including configuration mixing and meson exchange contributions.

  17. Doppler-Free Spectroscopy Measurements of Isotope Shifts and Hyperfine Components of Near-IR Xenon Lines

    SciTech Connect

    Mazouffre, S.; Pawelec, E.; Tran Bich, N.; Sadeghi, N.

    2006-01-15

    Xenon is currently used as propellant gas in electric thrusters, in which ejection of corresponding ions produces the desired thrust. As such a gas contains 9 stable isotopes, a non-intrusive determination of the velocity distribution function of atoms and ions in the thruster plasma plume, by means of absorption or fluorescence techniques, requires a precise knowledge of the line structure. We used Doppler-free Lamb-dip spectroscopy to determine isotopic shifts and hyperfine components of odd isotopes of several spectral lines of Xe atom and Xe+ ion in the 825 - 835 nm range.

  18. Theory of the Helium Isotope Shift

    SciTech Connect

    Pachucki, Krzysztof; Yerokhin, V. A.

    2015-09-15

    Theory of the isotope shift of the centroid energies of light few-electron atoms is reviewed. Numerical results are presented for the isotope shift of the 2{sup 3}P-2{sup 3}S and 2{sup 1}S-2{sup 3}S transition energies of {sup 3}He and {sup 4}He. By comparing theoretical predictions for the isotope shift with the experimental results, the difference of the squares of the nuclear charge radii of {sup 3}He and {sup 4}He, δR{sup 2}, is determined with high accuracy.

  19. Isotope shifts and coulomb displacement energies in calcium isotopes

    NASA Astrophysics Data System (ADS)

    Caurier, E.; Poves, A.; Zuker, A.

    1980-10-01

    Isotope shifts, neutron-proton radii differences and Coulomb displacement energies are calculated for calcium isotopes A = 41 to 48. A simple parametrization of the core polarization terms of the effective force in the framework of the Isospin Projected Hartree-Fock (IPHF) method leads to good agreement between theory and experiment.

  20. Isotope shift of the electric-dipole transition in Os-

    NASA Astrophysics Data System (ADS)

    Kellerbauer, A.; Canali, C.; Fischer, A.; Warring, U.; Fritzsche, S.

    2011-12-01

    The isotope shift of the bound-bound electric dipole transition at 1162.75 nm in the osmium anion was measured by high-precision collinear laser spectroscopy. The transition was observed in all naturally occurring isotopes, including 184Os- with a natural abundance of 0.02%. We combined the data with our prior measurements of the hyperfine structure in 187Os- and 189Os- and used them to determine experimental values for the isotope shift coefficients. The normal mass shift, specific mass shift, and field shift coefficients were found to be MNMS=141.4 GHz u, MSMS=2.4(12.6) THz u, and F=16.2(9.9) GHz fm-2, respectively. Theoretical values for the MSMS and F parameters were calculated based on a series of relativistic configuration interaction computations and a Fermi-like charge distribution and found to be in good agreement with the experimental values.

  1. Precise measurements of 203 Tl and 205 Tl excited state hyperfine splittings and isotope shifts using two-step vapor cell spectroscopy

    NASA Astrophysics Data System (ADS)

    Majumder, P. K.; Cheng, Sau Man; Rupasinghe, P. M.

    2016-05-01

    We have undertaken a series of high-precision atomic structure measurement in thallium to test ongoing ab initio atomic structure calculations of relevance to symmetry violation tests in this element. We are currently completing two-step spectroscopy measurements of the 8P1 / 2 and 8P3 / 2 hyperfine structure and isotope shift using a heated thallium vapor cell and two external cavity semiconductor diode lasers. One laser, locked to the thallium 6P1 / 2 --> 7S1 / 2 378 nm transition excites one or both naturally-occurring isotopes to an intermediate state. A second red laser overlaps the UV beam within the thallium vapor cell in both a co-propagating and counter-propagating configuration. Analysis of subsequent Doppler-free absorption spectra of the 7S1 / 2 --> 8P1 / 2 , 3 / 2 visible transitions allows us to extract both hyperfine and isotope shift information for these excited states with uncertainties below 1 MHz. Frequency modulation of the red laser provides convenient in situ frequency calibration. Recent measurements in our group have shown significant discrepancies from older hyperfine structure measurements in thallium excited states. Current results will be presented. Work supported by NSF Grant # 1404206.

  2. Analysis of measured and calculated Raman spectra of indole, 3-methylindole, and tryptophan on the basis of observed and predicted isotope shifts.

    PubMed

    Dieng, Senghane D; Schelvis, Johannes P M

    2010-10-14

    The aromatic amino acid tryptophan plays an important role in protein electron-transfer and in enzyme catalysis. Tryptophan is also used as a probe of its local protein environment and of dynamic changes in this environment. Raman spectroscopy of tryptophan has been an important tool to monitor tryptophan, its radicals, and its protein environment. The proper interpretation of the Raman spectra requires not only the correct assignment of Raman bands to vibrational normal modes but also the correct identification of the Raman bands in the spectrum. A significant amount of experimental and computational work has been devoted to this problem, but inconsistencies still persist. In this work, the Raman spectra of indole, 3-methylindole (3MI), tryptophan, and several of their isotopomers have been measured to determine the isotope shifts of the Raman bands. Density functional theory calculations with the B3LYP functional and the 6-311+G(d,p) basis set have been performed on indole, 3MI, 3-ethylindole (3EI), and several of their isotopomers to predict isotope shifts of the vibrational normal modes. Comparison of the observed and predicted isotope shifts results in a consistent assignment of Raman bands to vibrational normal modes that can be used for both assignment and identification of the Raman bands. For correct assignments, it is important to determine force field scaling factors for each molecule separately, and scaling factors of 0.9824, 0.9843, and 0.9857 are determined for indole, 3MI, and 3EI, respectively. It is also important to use more than one parameter to assign vibrational normal modes to Raman bands, for example, the inclusion of isotope shifts other than those obtained from H/D-exchange. Finally, the results indicate that the Fermi doublet of indole may consist of just two fundamentals, whereas one fundamental and one combination band are identified for the Fermi resonance that gives rise to the doublet in 3MI and tryptophan.

  3. Isotope shifts in spectra of molecular liquids

    NASA Astrophysics Data System (ADS)

    Dubrovskaya, E. V.; Kolomiitsova, T. D.; Shurukhina, A. V.; Shchepkin, D. N.

    2016-02-01

    In the IR absorption spectra of low-temperature molecular liquids, we have observed anomalously large isotope shifts of frequencies of vibrational bands that are strong in the dipole absorption. The same effect has also been observed in their Raman spectra. At the same time, in the spectra of cryosolutions, the isotope shifts of the same bands coincide with a high accuracy (±(0.1-0.5) cm-1) with the shifts that are observed in the spectra of the gas phase. The difference between the spectra of examined low-temperature systems is caused by the occurrence of resonant dipole-dipole interactions between spectrally active identical molecules. The calculation of the band contour in the spectrum of liquid freon that we have performed in this work taking into account the resonant interaction between states of simultaneous transitions in isotopically substituted molecules can explain this effect.

  4. Isotope shift in the sulfur electron affinity: Observation and theory

    SciTech Connect

    Carette, Thomas; Scharf, Oliver; Godefroid, Michel; Froese Fischer, Charlotte

    2010-04-15

    The sulfur electron affinities {sup e}A(S) are measured by photodetachment microscopy for the two isotopes {sup 32}S and {sup 34}S (16 752.975 3(41) and 16 752.977 6(85) cm{sup -1}, respectively). The isotope shift in the electron affinity is found to be more probably positive, {sup e}A({sup 34}S)- {sup e}A({sup 32}S) =+0.0023(70) cm{sup -1}, but the uncertainty allows for the possibility that it may be either ''normal''[{sup e}A({sup 34}S) > {sup e}A({sup 32}S)] or ''anomalous''[{sup e}A({sup 34}S) < {sup e}A({sup 32}S)]. The isotope shift is estimated theoretically using elaborate correlation models, monitoring the electron affinity and the mass polarization term expectation value. The theoretical analysis predicts a very large specific mass shift (SMS) that counterbalances the normal mass shift (NMS) and produces an anomalous isotope shift {sup e}A({sup 34}S)- {sup e}A({sup 32}S) =-0.0053(24) cm{sup -1}, field shift corrections included. The total isotope shift can always be written as the sum of the NMS (here +0.0169 cm{sup -1}) and a residual isotope shift (RIS). Since the NMS has nearly no uncertainty, the comparison between experimental and theoretical RIS is more fair. With respective values of -0.0146(70) cm{sup -1} and -0.0222(24) cm{sup -1}, these residual isotope shifts are found to agree within the estimated uncertainties.

  5. Hitting the moving target: modelling ontogenetic shifts with stable isotopes reveals the importance of isotopic turnover.

    PubMed

    Hertz, Eric; Trudel, Marc; El-Sabaawi, Rana; Tucker, Strahan; Dower, John F; Beacham, Terry D; Edwards, Andrew M; Mazumder, Asit

    2016-05-01

    Ontogenetic niche shifts are widely prevalent in nature and are important in shaping the structure and dynamics of ecosystems. Stable isotope analysis is a powerful tool to assess these shifts, with δ(15) N providing a measure of trophic level and δ(13) C a measure of energy source. Previous applications of stable isotopes to study ontogenetic niche shifts have not considered the appreciable time lag between diet and consumer tissue associated with isotopic turnover. These time lags introduce significant complexity into field studies of ontogenetic niche shifts. Juvenile Chinook salmon (Oncorhynchus tshawytscha) migrate from freshwater to marine ecosystems and shift their diet from feeding primarily on invertebrates to feeding primarily on fish. This dual ontogenetic habitat and diet shift, in addition to the long time lag associated with isotopic turnover, suggests that there is potential for a disconnect between the prey sources that juvenile salmon are consuming, and the inferred prey sources from stable isotopes. We developed a model that considered ontogenetic niche shifts and time lags associated with isotopic turnover, and compared this 'ontogeny' model to one that considered only isotopic turnover. We used a Bayesian framework to explicitly account for parameter uncertainty. Data showed overwhelming support for the ontogeny model relative to the isotopic turnover model. Estimated variables from best model fits indicate that the ontogeny model predicts a much greater reliance on fish prey than does the stomach content data. Overall, we found that this method of quantifying ontogenetic niche shifts effectively accounted for both isotopic turnover and ontogenetic diet shifts; a finding that could be widely applicable to a variety of systems. © 2016 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

  6. New Multidimensional Editing Experiments for Measurement of Amide Deuterium Isotope Effects on C βChemical Shifts in 13C, 15N-Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Meissner, Axel; Sørensen, Ole Winneche

    1998-12-01

    Novel multidimensional NMR pulse sequences for measurement of the three- and four-bond amide deuterium isotope effect on the chemical shifts of13Cβin proteins are presented. The sequences result in editing into two subspectra of a heteronuclear triple resonance spectrum {ω(N), ω(Cβ), ω(Hα)} according to there being a deuterium or a proton attached to15N for the pertinent correlations. The new experiments are demonstrated by an application to the first module of the13C,15N-labeled protein RAP 18-112 (N-terminal module of α2-macroglobulin receptor associated protein).

  7. Isotope shift of the ferromagnetic transition temperature in itinerant ferromagnets

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Takashi; Hase, Izumi; Odagiri, Kosuke

    2017-02-01

    We present a theory of the isotope effect of the Curie temperature Tc in itinerant ferromagnets. The isotope effect in ferromagnets occurs via the electron-phonon vertex correction and the effective attractive interaction mediated by the electron-phonon interaction. The decrease of the Debye frequency increases the relative strength of the Coulomb interaction, which results in a positive isotope shift of Tc when the mass M of an atom increases. Following this picture, we evaluate the isotope effect of Tc by using the Stoner theory and a spin-fluctuation theory. When Tc is large enough as large as or more than 100 K, the isotope effect on Tc can be measurable. Recently, precise measurements on the oxygen isotope effect on Tc have been performed for itinerant ferromagnet SrRuO3 with Tc ∼ 160 K. A clear isotope effect has been observed with the positive shift of Tc ∼ 1 K by isotope substitution (16O →18O). This experimental result is consistent with our theory.

  8. Measurement of Isotope Shifts, Hyperfine Splittings and Stark Shift for the Ytterbium (6S)2 SINGLET-S(0) to (6S6P) TRIPLET-P(1) Transition Using AN Acousto-Optically Modulated Laser Beam.

    NASA Astrophysics Data System (ADS)

    Li, Jian

    1995-11-01

    Accurate measurements of isotope shifts, hyperfine splittings and Stark shifts are of interest for studying atomic structure. This thesis reports a new method to precisely measure small frequency intervals. This was done using an acousto-optic modulator to frequency shift part of a laser beam. The frequency shifted and unshifted laser beams were then superimposed and excited an atomic beam. The laser frequency was scanned across the transition while fluorescence produced by the radiative decay of the excited state was detected by a photomultiplier. Each transition generated two peaks in the spectrum separated by the acousto-optic modulation frequency, which permitted the frequency to be calibrated. This method was tested by measuring the isotope shifts and hyperfine splittings of the ytterbium rm (6s)^2 ^1S_0to(6s6p) ^3P_1 transition at 555.6 nm. The shifts (MHz) relative to ^{176} Yb are: ^{173}Yb {it F}=7/2,-1432.1+/-1.2; ^{171}Yb {it F}=1/2, -1176.9+/-1.1; ^{174}Yb, 953.8+/-1.0; ^{172}Yb 1953.9+/-1.6; ^{170}Yb 3240.4+/-2.8; ^{173}Yb {it F}=5/2,3265.8+/-2.8; ^ {168}Yb, 4611.9+/-4.4; ^ {171,173}Yb {it F}=3/2,4760.1 +/-3.7 where the negative sign indicates that the transition occurs at a lower frequency than in ^{176}Yb. The magnetic dipole (a) and electric quadrupole (b) hyperfine coupling constants (MHz) of the (6s6p) ^3P_1 state for ^{171,173}Yb were determined to be a_{171}=3959.1 +/-3.0, a_{173}=-1094.44+/-0.84 and b_{173}=-827.89+/-0.85. These results were in agreement with the most accurate data found in the literature that were obtained by measuring frequency shifts using a Fabry Perot etalon whose length was stabilized with a helium neon laser locked to an iodine line. In contrast, our method uses cheaper and simpler apparatus. Next, the Stark shift of the ytterbium rm (6s)^2 ^1S_0to(6s6p) ^3P_1 transition was measured by passing the atomic beam through a uniform electric field. The Stark shift rate was found to be -15.419+/-0.048 kHz/(kV/cm)^2. No

  9. Isotope shifts in francium isotopes Fr 206 - 213 and Fr 221

    DOE PAGES

    Collister, R.; Gwinner, G.; Tandecki, M.; ...

    2014-11-07

    We present the isotope shifts of the 7s1/2 to 7p1/2 transition for francium isotopes ²⁰⁶⁻²¹³Fr with reference to ²²¹Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7s1/2 to 7p3/2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D₁ and D₂ transitions, of sufficient precision to differentiate between ab initio calculations.

  10. Constraining new physics models with isotope shift spectroscopy

    NASA Astrophysics Data System (ADS)

    Frugiuele, Claudia; Fuchs, Elina; Perez, Gilad; Schlaffer, Matthias

    2017-07-01

    Isotope shifts of transition frequencies in atoms constrain generic long- and intermediate-range interactions. We focus on new physics scenarios that can be most strongly constrained by King linearity violation such as models with B -L vector bosons, the Higgs portal, and chameleon models. With the anticipated precision, King linearity violation has the potential to set the strongest laboratory bounds on these models in some regions of parameter space. Furthermore, we show that this method can probe the couplings relevant for the protophobic interpretation of the recently reported Be anomaly. We extend the formalism to include an arbitrary number of transitions and isotope pairs and fit the new physics coupling to the currently available isotope shift measurements.

  11. Measurement of the {}^{{20,22}}Ne {}^{3}{{\\rm{P}}}_{2}{{\\rm{{--}}}}^{3}{{\\rm{D}}}_{3} transition isotope shift using a single, phase-modulated laser beam

    NASA Astrophysics Data System (ADS)

    Ohayon, B.; Gumpel, G.; Ron, G.

    2017-03-01

    We develop a simple technique to accurately measure frequency differences between far-lying resonances in a spectroscopy signal using a single, unlocked laser. This technique was used to measure the isotope shift (IS) of the cooling transition of metastable neon. Our result of 1626.287(53) MHz is the most accurate determination of this value to date.

  12. Isotope shift constant and nuclear charge model

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Redi, O.; Stroke, H. H.

    1992-04-01

    We use the method of Zimmermann [Z. Phys. A 321 (1985) 23-30], which he used to calculate the isotope shift constant for a uniform nuclear charge distribution, to obtain it for a diffuse nuclear charge model. The two models give results that differ slightly on the level of precision of current experiments. The same parameters are used to calculate the model sensitivity of the contributions to the isotope shifts of higher moments of the nuclear charge distribution as formulated by Seltzer [Phys. Rev. 188 (1969) 1916-1919]. These are found to be essentially model independent. Tables are given of the numerical calculations. Nous employons la méthode de Zimmermann [Z. Phys. A 321 (1985) 23-30], qu'il avait utilisé dans un calcul de la constante du déplacement isotopique pour une distribution de charge uniforme, pour l'obtenir avec un modèle de charge nucléaire avec forme quasi-trapézoïdale. Les deux modèles donnent des résultats dont la difference excède de peu la précision des mesures actuelles. Les mêmes paramètres sont utilisés pour comparer la dépendance aux deux modèles de la contribution au déplacement isotopique des moments plus élevés de la distribution de la charge nucléaire dans la formulation de Seltzer [Phys. Rev. 188 (1969) 1916-1919]. On trouve que ces contributions sont essentiellement indépendantes du modèle. Des tables de calculs numériques sont présentées.

  13. Isotonic similarities in isotope shifts from Hg to Ra.

    NASA Astrophysics Data System (ADS)

    Stroke, H. H.

    2003-04-01

    Isotope shifts (IS) in atomic spectra of heavy elements reflect largely the variation in of the nuclear charge distribution. Our early systematic measurements of IS for an extended range of stable and radioactive isotopes and nuclear isomers in Tl and Hg^1 showed that by displaying the relative IS, normalized to a chosen pair of isotopes, there was a striking similarity for the IS of isotones. This essentially divides out the electronic factor in the IS and allows the comparison of Δ for neighboring Z as N is varied. Following our further studies on Pb and Bi^2 and those on Fr at ISOLDE by the Orsay spectroscopy group^3, we found that the isotonic similarity extended to these elements. Since then, many additional measurements were made, principally at ISOLDE^4, extending to Ra the elements studied. The isotonic shift similarities persist from Z=80 to 88. We noted that the relative isotope and isomer shifts can be used to investigate the polarization of the nucleus by the added neutrons, a model used in a calculation by Barrett.^5 . The new data may serve further in this direction. ^1W,J.Tomlinson, H.H. Stroke, Nucl.Phys. 60, 614 (1964). ^2M. Barboza-Flores et al., Z.Phys. A 321, 85 (1985), ^3S. Liberman et al., Phys .Rev. A 22, 2732 (1980). ^4E,g. M.R. Pearson et al., J.Phys. G 26, 1829 (2000). ^5R.C. Barrett, Nucl. Phys. 88, 128 (1966).

  14. Rising atmospheric methane: 2007-2014 growth and isotopic shift

    NASA Astrophysics Data System (ADS)

    Nisbet, E. G.; Dlugokencky, E. J.; Manning, M. R.; Lowry, D.; Fisher, R. E.; France, J. L.; Michel, S. E.; Miller, J. B.; White, J. W. C.; Vaughn, B.; Bousquet, P.; Pyle, J. A.; Warwick, N. J.; Cain, M.; Brownlow, R.; Zazzeri, G.; Lanoisellé, M.; Manning, A. C.; Gloor, E.; Worthy, D. E. J.; Brunke, E.-G.; Labuschagne, C.; Wolff, E. W.; Ganesan, A. L.

    2016-09-01

    From 2007 to 2013, the globally averaged mole fraction of methane in the atmosphere increased by 5.7 ± 1.2 ppb yr-1. Simultaneously, δ13CCH4 (a measure of the 13C/12C isotope ratio in methane) has shifted to significantly more negative values since 2007. Growth was extreme in 2014, at 12.5 ± 0.4 ppb, with a further shift to more negative values being observed at most latitudes. The isotopic evidence presented here suggests that the methane rise was dominated by significant increases in biogenic methane emissions, particularly in the tropics, for example, from expansion of tropical wetlands in years with strongly positive rainfall anomalies or emissions from increased agricultural sources such as ruminants and rice paddies. Changes in the removal rate of methane by the OH radical have not been seen in other tracers of atmospheric chemistry and do not appear to explain short-term variations in methane. Fossil fuel emissions may also have grown, but the sustained shift to more 13C-depleted values and its significant interannual variability, and the tropical and Southern Hemisphere loci of post-2007 growth, both indicate that fossil fuel emissions have not been the dominant factor driving the increase. A major cause of increased tropical wetland and tropical agricultural methane emissions, the likely major contributors to growth, may be their responses to meteorological change.

  15. ESTIMATING THE TIMING OF DIET SHIFTS USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analysis has become an important tool in studies of trophic food webs and animal feeding patterns. When animals undergo rapid dietary shifts due to migration, metamorphosis, or other reasons, the isotopic composition of their tissues begins changing to reflect tha...

  16. ESTIMATING THE TIMING OF DIET SHIFTS USING STABLE ISOTOPES

    EPA Science Inventory

    Stable isotope analysis has become an important tool in studies of trophic food webs and animal feeding patterns. When animals undergo rapid dietary shifts due to migration, metamorphosis, or other reasons, the isotopic composition of their tissues begins changing to reflect tha...

  17. Isotope shifts and hyperfine structure in polonium isotopes by atomic-beam laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Kowalewska, D.; Bekk, K.; Göring, S.; Hanser, A.; Kälber, W.; Meisel, G.; Rebel, H.

    1991-08-01

    Laser-induced fluorescence spectroscopy in a collimated atomic beam has been applied to determine isotope shifts and the hyperfine structure of an isotopic chain of the radioactive element polonium (200Po, 202Po, 204-210Po). The relative isotope shifts show a striking similarity with results for other elements in the vicinity of Pb, even reproducing details of the odd-even staggering.

  18. Cometary Isotopic Measurements

    NASA Astrophysics Data System (ADS)

    Bockelée-Morvan, Dominique; Calmonte, Ursina; Charnley, Steven; Duprat, Jean; Engrand, Cécile; Gicquel, Adeline; Hässig, Myrtha; Jehin, Emmanuël; Kawakita, Hideyo; Marty, Bernard; Milam, Stefanie; Morse, Andrew; Rousselot, Philippe; Sheridan, Simon; Wirström, Eva

    2015-12-01

    Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. We review here measurements acquired on the D/H, 14N/15N, 16O/18O, 12C/13C, and 32S/34S ratios in cometary grains and gases, and discuss their cosmogonic implications. The review includes analyses of potential cometary material available in collections on Earth, recent measurements achieved with the Herschel Space Observatory, large optical telescopes, and Rosetta, as well as recent results obtained from models of chemical-dynamical deuterium fractionation in the early solar nebula. Prospects for future measurements are presented.

  19. Lamb Shift Measurements

    NASA Astrophysics Data System (ADS)

    Pipkin, Francis M.

    The following sections are included: * INTRODUCTION * SUMMARY OF THEORY * CALCULATION OF SIGNALS * SLOW BEAM MEASUREMENTS * BOTTLE EXPERIMENTS * FAST BEAM EXPERIMENTS * Stark Quenching * Anisotropy of Quench Radiation * Quantum Beat Experiments * Atomic Interferometer * Fast Beam Radiofrequency Experiments * Single Field * Separated Oscillatory Fields * Fast Beam Laser Resonance * LASER SPECTROSCOPY * DIRECT MEASUREMENT OF LYMAN-a RADIATION * EXOTIC ATOMS * TWO ELECTRON ATOMS * COMPARISON OF THEORY AND EXPERIMENT * Hydrogne * Helium * High Z Atoms * PROSPECTS * ACKNOWLEDGEMENTS * References

  20. Isotope shift and search for metastable superheavy elements in astrophysical data

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Flambaum, V. V.; Webb, J. K.

    2017-06-01

    We explore a possibility that astrophysical data may contain spectra of metastable nuclei belonging to the island of stability where the nuclei have a magic number of neutrons of N =184 . The laboratory-produced nuclei have a significantly smaller number of neutrons. To identify spectra of the N =184 isotopes of these nuclei and their neutron-rich superheavy decay products in astrophysical data we calculate the isotope shift which should be added to the laboratory-measured wavelengths. The results for the isotope shifts in the strongest optical electromagnetic transitions in No, Lr, Nh, Fl, and Z =120 elements are presented.

  1. Calculation of isotope shifts for cesium and francium

    SciTech Connect

    Dzuba, V.A.; Johnson, W.R.; Safronova, M.S.

    2005-08-15

    We perform ab initio calculations of isotope shifts for isotopes of cesium (from A=123 to A=137) and francium (from A=207 to A=228). These calculations start from the relativistic Hartree-Fock method and make use of several techniques to include correlations. The field (volume) isotope shift is calculated by means of an all-order correlation potential method and within the singles-doubles-partial-triples linearized coupled-cluster approach. Many-body perturbation theory in two different formulations is used to calculate the specific mass shift. We discuss the strong points and shortcomings of the different approaches and implications for parity nonconservation in atoms. Changes in nuclear charge radii are found by comparing the present calculations with experiment.

  2. Modeling nuclear field shift isotope fractionation in crystals

    NASA Astrophysics Data System (ADS)

    Schauble, E. A.

    2013-12-01

    In this study nuclear field shift fractionations in solids (and chemically similar liquids) are estimated using calibrated density functional theory calculations. The nuclear field shift effect is a potential driver of mass independent isotope fractionation(1,2), especially for elements with high atomic number such as Hg, Tl and U. This effect is caused by the different shapes and volumes of isotopic nuclei, and their interactions with electronic structures and energies. Nuclear field shift isotope fractionations can be estimated with first principles methods, but the calculations are computationally difficult, limiting most theoretical studies so far to small gas-phase molecules and molecular clusters. Many natural materials of interest are more complex, and it is important to develop ways to estimate field shift effects that can be applied to minerals, solutions, in biomolecules, and at mineral-solution interfaces. Plane-wave density functional theory, in combination with the projector augmented wave method (DFT-PAW), is much more readily adapted to complex materials than the relativistic all-electron calculations that have been the focus of most previous studies. DFT-PAW is a particularly effective tool for studying crystals with periodic boundary conditions, and may also be incorporated into molecular dynamics simulations of solutions and other disordered phases. Initial calibrations of DFT-PAW calculations against high-level all-electron models of field shift fractionation suggest that there may be broad applicability of this method to a variety of elements and types of materials. In addition, the close relationship between the isomer shift of Mössbauer spectroscopy and the nuclear field shift isotope effect makes it possible, at least in principle, to estimate the volume component of field shift fractionations in some species that are too complex even for DFT-PAW models, so long as there is a Mössbauer isotope for the element of interest. Initial results

  3. Backbone dynamics of a model membrane protein: measurement of individual amide hydrogen-exchange rates in detergent-solubilized M13 coat protein using /sup 13/C NMR hydrogen/deuterium isotope shifts

    SciTech Connect

    Henry, G.D.; Weiner, J.H.; Sykes, B.D.

    1987-06-16

    Hydrogen-exchange rates have been measured for individual assigned amide protons in M13 coat protein, a 50-residue integral membrane protein, using a /sup 13/C nuclear magnetic resonance (NMR) equilibrium isotope shift technique. The locations of the more rapidly exchanging amides have been determined. In D/sub 2/O solutions, a peptide carbonyl resonance undergoes a small upfield isotope shift (0.08-0.09 ppm) from its position in H/sub 2/O solutions; in 1:1 H/sub 2/O/D/sub 2/O mixtures, the carbonyl line shape is determined by the exchange rate at the adjacent nitrogen atom. M13 coat protein was labeled biosynthetically with /sup 13/C at the peptide carbonyls of alanine, glycine, phenylalanine, proline, and lysine, and the exchange rates of 12 assigned amide protons in the hydrophilic regions were measured as a function of pH by using the isotope shift method. This equilibrium technique is sensitive to the more rapidly exchanging protons which are difficult to measure by classical exchange-out experiments. In proteins, structural factors, notably H bonding, can decrease the exchange rate of an amide proton by many orders of magnitude from that observed in the freely exposed amides of model peptides such as poly(DL-alanine). With corrections for sequence-related inductive effects, the retardation of amide exchange in sodium dodecyl sulfate solubilized coat protein has been calculated with respect to poly(DL-alanine). The most rapidly exchanging protons, which are retarded very little or not at all, are shown to occur at the N- and C-termini of the molecule. A model of the detergent-solubilized coat protein is constructed from these H-exchange data which is consistent with circular dichroism and other NMR results.

  4. Lifetime measurement of candidate chiral doublet bands in the {sup 103,104}Rh isotopes with the recoil-distance Doppler-shift method in inverse kinematics

    SciTech Connect

    Suzuki, T.; Rainovski, G.; Koike, T.; Ahn, T.; Costin, A.; Carpenter, M. P.; Janssens, R. V. F.; Lister, C. J.; Zhu, S.; Danchev, M.; Dewald, A.; Joshi, P.; Wadsworth, R.; Moeller, O.; Pietralla, N.; Shinozuka, T.; Timar, J.; Vaman, C.

    2008-09-15

    Lifetimes of chiral candidate structures in {sup 103,104}Rh were measured using the recoil distance Doppler-shift method. The Gammasphere detector array was used in conjunction with the Cologne plunger device. Excited states of {sup 103,104}Rh were populated by the {sup 11}B({sup 96}Zr,4n){sup 103}Rh and {sup 11}B({sup 96}Zr,3n){sup 104}Rh fusion-evaporation reactions in inverse kinematics. Three and five lifetimes of levels belonging to the proposed chiral doublet bands are measured in {sup 103}Rh and {sup 104}Rh, respectively. The previously observed even-odd spin dependence of the B(M1)/B(E2) values is caused by the variation in the B(E2) values, whereas the B(M1) values decrease as a function of spin.

  5. First Principle Predictions of Isotopic Shifts in H2O

    NASA Technical Reports Server (NTRS)

    Schwenke, David W.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    We compute isotope independent first and second order corrections to the Born-Oppenheimer approximation for water and use them to predict isotopic shifts. For the diagonal correction, we use icMRCI wavefunctions and derivatives with respect to mass dependent, internal coordinates to generate the mass independent correction functions. For the non-adiabatic correction, we use scaled SCF/CIS wave functions and a generalization of the Handy method to obtain mass independent correction functions. We find that including the non-adiabatic correction gives significantly improved results compared to just including the diagonal correction when the Born-Oppenheimer potential energy surface is optimized for H2O-16. The agreement with experimental results for deuterium and tritium containing isotopes is nearly as good as our best empirical correction, however, the present correction is expected to be more reliable for higher, uncharacterized levels.

  6. Nitrogen Isotope Evidence for a Shift in Eastern Beringian Nitrogen Cycle after the Terminal Pleistocene

    NASA Astrophysics Data System (ADS)

    Tahmasebi, F.; Longstaffe, F. J.; Zazula, G.

    2016-12-01

    The loess deposits of eastern Beringia, a region in North America between 60° and 70°N latitude and bounded by Chukchi Sea to the west and the Mackenzie River to the east, are a magnificent repository of Late Pleistocene megafauna fossils. The stable carbon and nitrogen isotope compositions of these fossils are measured to determine the paleodiet of these animals, and hence the paleoenvironment of this ecosystem during the Quaternary. For this approach to be most successful, however, requires consideration of possible changes in nutrient cycling and hence the carbon and nitrogen isotopic compositions of vegetation in this ecosystem. To test for such a shift following the terminal Pleistocene, we analyzed the stable carbon and nitrogen isotope compositions of modern plants and bone collagen of Arctic ground squirrels from Yukon Territory, and fossil plants and bones recovered from Late Pleistocene fossil Arctic ground squirrel nests. The data for modern samples provided a measure of the isotopic fractionation between ground squirrel bone collagen and their diet. The over-wintering isotopic effect of decay on typical forage grasses was also measured to evaluate its role in determining fossil plant isotopic compositions. The grasses showed only a minor change ( 0-1 ‰) in carbon isotope composition, but a major change ( 2-10 ‰) in nitrogen isotope composition over the 317-day experiment. Based on the modern carbon isotope fractionation between ground squirrel bone collagen and their diet, the modern vegetation carbon isotopic baseline provides a suitable proxy for the Late Pleistocene of eastern Beringia, after accounting for the Suess effect. However, the predicted nitrogen isotope composition of vegetation comprising the diet of fossil ground squirrels remains 2.5 ‰ higher than modern grasslands in this area, even after accounting for possible N-15 enrichment during decay. This result suggests a change in N cycling in this region since the Late Pleistocene.

  7. Temporal dietary shift in jellyfish revealed by stable isotope analysis.

    PubMed

    Javidpour, Jamileh; Cipriano-Maack, Ashlie N; Mittermayr, Agnes; Dierking, Jan

    A temporal change in the stable isotope (SI) composition of jellyfish in the Kiel Fjord, Western Baltic Sea, was documented by analyzing δ(13)C, δ(15)N and δ(34)S of bell tissue of Aurelia aurita and Cyanea capillata in the period between June and October 2011. A strong and significant temporal change in all SI values of A. aurita was found, including an increase of ~3 ‰ in δ(13)C, a decrease of ~4 ‰ in δ(15)N and sharp decline of ~7 ‰ in δ(34)S. While knowledge gaps in jellyfish isotope ecology, in particular the lack of reliable trophic enrichment factors, call for a conservative interpretation of our data, observed changes in particular in δ(34)S, as indicated by means of a MixSIR mixing model, would be consistent with a temporal dietary shift in A. aurita from mesozooplankton (>150 µm) to microplankton and small re-suspended particles (0.8-20 µm) from the benthos. Presence of a hitherto unidentified food source not included in the model could also contribute to the shift. During the 2-month occurrence of C. capillata, its isotope composition remained stable and was consistent with a mainly mesozooplanktonic diet. Mixing model output, mainly driven by δ(34)S values, indicated a lower proportion of A. aurita in the diet of C. capillata than previously reported, and thus to a potentially lesser importance of intraguild predation among jellyfish in the Kiel Fjord. Overall, our results clearly highlighted the potential for substantial intraspecific isotopic seasonal variation in jellyfish, which should be taken into account in future feeding ecology studies on this group.

  8. Isotope shift of the electric-dipole transition in Os{sup -}

    SciTech Connect

    Kellerbauer, A.; Canali, C.; Fischer, A.; Warring, U.; Fritzsche, S.

    2011-12-15

    The isotope shift of the bound-bound electric dipole transition at 1162.75 nm in the osmium anion was measured by high-precision collinear laser spectroscopy. The transition was observed in all naturally occurring isotopes, including {sup 184}Os{sup -} with a natural abundance of 0.02%. We combined the data with our prior measurements of the hyperfine structure in {sup 187}Os{sup -} and {sup 189}Os{sup -} and used them to determine experimental values for the isotope shift coefficients. The normal mass shift, specific mass shift, and field shift coefficients were found to be M{sub NMS}=141.4 GHz u, M{sub SMS}=2.4(12.6) THz u, and F=16.2(9.9) GHz fm{sup -2}, respectively. Theoretical values for the M{sub SMS} and F parameters were calculated based on a series of relativistic configuration interaction computations and a Fermi-like charge distribution and found to be in good agreement with the experimental values.

  9. Isotope shifts and hyperfine structure of the Fe I 372-nm resonance line

    SciTech Connect

    Krins, S.; Huet, N.; Bastin, T.; Oppel, S.; Zanthier, J. von

    2009-12-15

    We report measurements of the isotope shifts of the 3d{sup 6}4s{sup 2} a {sup 5}D{sub 4}-3d{sup 6}4s4p z {sup 5}F{sub 5}{sup o} Fe I resonance line at 372 nm between all four stable isotopes {sup 54}Fe, {sup 56}Fe, {sup 57}Fe, and {sup 58}Fe, as well as the complete hyperfine structure of that line for {sup 57}Fe, the only stable isotope having a nonzero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant A of the excited state of the transition in {sup 57}Fe: A(3d{sup 6}4s4p z {sup 5}F{sub 5}{sup o})=81.69(86) MHz. The measurements were carried out by means of high-resolution Doppler-free laser saturated absorption spectroscopy in a Fe-Ar hollow cathode discharge cell using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.

  10. Rising methane: post-2007 growth, geographic loci, timings and isotopic shift

    NASA Astrophysics Data System (ADS)

    Nisbet, Euan G.; Manning, Martin R.; Dlugokencky, Ed; Lowry, David; Fisher, Rebecca E.; Brownlow, Rebecca

    2017-04-01

    Atmospheric methane is rising rapidly again, after a period of stability [1]. NOAA report a global growth rate from 2007-2013 of 5.7±1.2 ppb yr-1, followed by extreme growth of 12.6±0.5 ppb in 2014 and 10.0±0.7 ppb in 2015. Growth has been accompanied by a shift in δ13C(CH4) (a measure of the 13C/12C isotope ratio in methane) to significantly more negative values since 2007. This isotopic shift has been observed in independently calibrated NOAA, Royal Holloway and NIWA-New Zealand measurements: thus the negative trend is real, global, and not a calibration artifact. Fossil fuel methane emissions, which are mostly more positive than atmospheric values, are not driving the rise in methane. Instead, the geographic loci of post-2007 growth, and the timings of the methane rise and isotopic shift suggest growth was dominated by significant increases in biogenic methane emissions, particularly in the tropics and Southern Hemisphere: for example in years with heavy rainfall under the Inter-Tropical Convergence, from wetlands and increased agricultural sources such as ruminants and rice paddies. Changes in the removal rate of methane by the OH radical or other sinks may also have occurred but do not appear fully to explain short term variations in methane isotopes. All these drivers of rising methane - wetlands, ruminants, changing sinks - may reflect underlying decade-long trends in tropical climate: methane may thus be an important climate-change signal. 1. Nisbet, E.G. et al. (2016) Rising atmospheric methane: 2007-2014 growth and isotopic shift, Global Biogeochem. Cycles, 30, doi:10.1002/ 2016GB005406.

  11. Four-bond deuterium isotope effects on the chemical shifts of amide nitrogens in proteins.

    PubMed

    Tugarinov, Vitali

    2013-11-01

    An approach towards precision NMR measurements of four-bond deuterium isotope effects on the chemical shifts of backbone amide nitrogen nuclei in proteins is described. Three types of four-bond (15) N deuterium isotope effects are distinguished depending on the site of proton-to-deuterium substitution: (4)ΔN(N(i-1)D), (4)ΔN(N(i+1)D) and (4)ΔN(Cβ,(i-1)D). All the three types of isotope shifts are quantified in the (partially) deuterated protein ubiquitin. The (4)ΔN(N(i+1)D) and (4)ΔN(C(β,i-1)D) effects are by far the largest in magnitude and vary between 16 and 75 ppb and -18 and 46 ppb, respectively. A semi-quantitative correlation between experimental (4)ΔN(N(i+1)D) and (4)ΔN(C(β,i-1)D) values and the distances between nitrogen nuclei and the sites of (1)H-to-D substitution is noted. The largest isotope shifts in both cases correspond to the shortest inter-nuclear distances. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Environmental Implications of Ediacaran C-isotopic Shifts

    NASA Astrophysics Data System (ADS)

    Kelly, A. E.; Rothman, D. H.; Love, G. D.; Grosjean, E.; Fike, D. A.; Zumberge, J. E.; Summons, R. E.

    2008-12-01

    Compound-specific carbon isotope analyses of biomarkers show a widespread reversal in isotopic patterns in the Ediacaran. We analyzed oils and/or rocks from Eastern Siberia, Oman and Australia and confirmed that, in sediments and oils older than ~550 Ma, n-alkanes are enriched in 13C relative to the acyclic isoprenoids pristane and phytane. In younger sediments, the n-alkanes are depleted compared to these isoprenoids with the possible exception of those deposited during Phanerozoic oceanic anoxic events.1 Pristane and phytane are considered to be derived from photosynthetic primary inputs and, based on established biosynthetic relationships of organisms that dominate the modern ocean, should be 13C- enriched relative to n-alkanes from the same source. Therefore, the presence of n-alkanes with anomalously enriched isotopic compositions before 550 Ma may signify a high relative abundance of bacterial heterotrophs that extensively recycled organic matter (Corg) in the water column.2 The switch from anomalous isotopic ordering to isoprenoid: n-alkyl biosynthetic relationships characteristic of the Phanerozoic is observed to take place in the Ediacaran. In Oman, this coincides with the termination of the Shuram Excursion when marine carbonates show very negative δ13C values with no corresponding shift in the isotopic composition of co-occurring Corg.3 This has been attributed to the oxidation of a large pool of Corg in the deep ocean3 with a corresponding fundamental change in C-cycle dynamics.4 Several hypotheses, many ultimately linked to release of molecular oxygen via enhanced Corg burial, have been proposed to explain these phenomena. They include the evolution of: bilaterian animals with guts that rapidly export organic matter to the ocean floor as fecal pellets, reducing the amount of heterotrophy in the water column,2 biomineralization, providing ballast for organic export,4 and algae with decay-resistant biopolymers.4 Alternatively, tectonism and the rifting

  13. MCDHF calculations of isotope shifts of even-parity fine-structure levels in neutral osmium

    NASA Astrophysics Data System (ADS)

    Palmeri, P.; Quinet, P.; Bouazza, S.

    2016-12-01

    Ab initio multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations have been carried out in order to determine the isotope shifts of all the fine-structure levels belonging to the even-parity configurations (5d+6s)8 in neutral osmium, Os I. The theoretical predictions have been compared to laser spectroscopy measurements available in the literature showing a good agreement between theory and experiment.

  14. Hyperfine structure and isotope shifts of transitions in neutral and singly ionized ytterbium

    NASA Technical Reports Server (NTRS)

    Berends, R. W.; Maleki, L.

    1992-01-01

    The present experimental investigation of the hyperfine structure and isotopic shifts of transitions in neutral and singly-ionized Yb, which constitute a system of some interest to microwave-frequency standards, used counterpropagating pump and probe laser beams directed through a hollow-cathode discharge lamp. The results obtained are in agreement with previous measurements except in the case of the Yb-173(+) 6 2P0 sub 3/2 state, which is more accurately determined.

  15. Isotope shift and hyperfine splitting of the 4s{yields}5p transition in potassium

    SciTech Connect

    Behrle, Alexandra; Koschorreck, Marco; Koehl, Michael

    2011-05-15

    We have investigated the 4s {sup 2}S{sub 1/2}{yields}5p {sup 2}P{sub 1/2} transition (D{sub 1} line) of the potassium isotopes {sup 39}K, {sup 40}K, and {sup 41}K using Doppler-free laser saturation spectroscopy. Our measurements reveal the hyperfine splitting of the 5p {sup 2}P{sub 1/2} state of {sup 40}K, and we have determined the specific mass shift and the nuclear field shift constants for the blue (405 nm) D{sub 1} line.

  16. Measurement of the He 1s2s (1)S(0) isotopic shift using a tunable VUV anti-Stokes light source.

    PubMed

    Falcone, R W; Willison, J R; Young, J F; Harris, S E

    1978-11-01

    We describe a high-resolution, vacuum-ultraviolet spectroscopic technique based on a tunable, narrow-band, VUV, spontaneous anti-Stokes light source. The technique was used to measure the absolute energies of the 1s2s (1)S(0) states of (3)He and (4)He; the 1s2s (1)S(0) level of (3)He is 7.8 +/- 0.5 cm(-1) below that of (4)He.

  17. RIS3: A program for relativistic isotope shift calculations

    NASA Astrophysics Data System (ADS)

    Nazé, C.; Gaidamauskas, E.; Gaigalas, G.; Godefroid, M.; Jönsson, P.

    2013-09-01

    An atomic spectral line is characteristic of the element producing the spectrum. The line also depends on the isotope. The program RIS3 (Relativistic Isotope Shift) calculates the electron density at the origin and the normal and specific mass shift parameters. Combining these electronic quantities with available nuclear data, isotope-dependent energy level shifts are determined. Program summaryProgram title:RIS3 Catalogue identifier: ADEK_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADEK_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5147 No. of bytes in distributed program, including test data, etc.: 32869 Distribution format: tar.gz Programming language: Fortran 77. Computer: HP ProLiant BL465c G7 CTO. Operating system: Centos 5.5, which is a Linux distribution compatible with Red Hat Enterprise Advanced Server. Classification: 2.1. Catalogue identifier of previous version: ADEK_v1_0 Journal reference of previous version: Comput. Phys. Comm. 100 (1997) 81 Subprograms used: Cat Id Title Reference ADZL_v1_1 GRASP2K VERSION 1_1 to be published. Does the new version supersede the previous version?: Yes Nature of problem: Prediction of level and transition isotope shifts in atoms using four-component relativistic wave functions. Solution method: The nuclear motion and volume effects are treated in first order perturbation theory. Taking the zero-order wave function in terms of a configuration state expansion |Ψ>=∑μcμ|Φ(γμPJMj)>, where P, J and MJ are, respectively, the parity and angular quantum numbers, the electron density at the nucleus and the normal and specific mass shift parameters may generally be expressed as ∑cμcν<γμPJMj|V|γνPJMj> where V is the relevant operator. The matrix elements, in turn, can be expressed as sums over radial

  18. Nonlinear detection of secondary isotopic chemical shifts in NMR through spin noise

    PubMed Central

    Pöschko, Maria Theresia; Rodin, Victor V.; Schlagnitweit, Judith; Müller, Norbert; Desvaux, Hervé

    2017-01-01

    The detection of minor species in the presence of large amounts of similar main components remains a key challenge in analytical chemistry, for instance, to obtain isotopic fingerprints. As an alternative to the classical NMR scheme based on coherent excitation and detection, here we introduce an approach based on spin-noise detection. Chemical shifts and transverse relaxation rates are determined using only the detection circuit. Thanks to a nonlinear effect in mixtures with small chemical shift dispersion, small signals on top of a larger one can be observed with increased sensitivity as bumps on a dip; the latter being the signature of the main magnetization. Experimental observations are underpinned by an analytical theory: the coupling between the magnetization and the coil provides an amplified detection capability of both small static magnetic field inhomogeneities and small NMR signals. This is illustrated by two-bond 12C/13C isotopic measurements. PMID:28067218

  19. Nonlinear detection of secondary isotopic chemical shifts in NMR through spin noise

    NASA Astrophysics Data System (ADS)

    Pöschko, Maria Theresia; Rodin, Victor V.; Schlagnitweit, Judith; Müller, Norbert; Desvaux, Hervé

    2017-01-01

    The detection of minor species in the presence of large amounts of similar main components remains a key challenge in analytical chemistry, for instance, to obtain isotopic fingerprints. As an alternative to the classical NMR scheme based on coherent excitation and detection, here we introduce an approach based on spin-noise detection. Chemical shifts and transverse relaxation rates are determined using only the detection circuit. Thanks to a nonlinear effect in mixtures with small chemical shift dispersion, small signals on top of a larger one can be observed with increased sensitivity as bumps on a dip; the latter being the signature of the main magnetization. Experimental observations are underpinned by an analytical theory: the coupling between the magnetization and the coil provides an amplified detection capability of both small static magnetic field inhomogeneities and small NMR signals. This is illustrated by two-bond 12C/13C isotopic measurements.

  20. Measurement of isotope ratio of Ca{sup +} ions in a linear Paul Trap

    SciTech Connect

    Hashimoto, Y.; Minamino, K.; Nagamoto, D.; Hasegawa, S.

    2009-03-17

    Measurement of isotope ratios of Calcium is very useful in many fields. So we demonstrated the measurement of isotope ratios of {sup 40}Ca{sup +}(abundance 96.4%) to {sup 44}Ca{sup +}(2.09%) ions in a linear Paul trap with several laser lights tuning to the isotope shifts. And we found that the experimental parameters had large influences on the measurement of the isotope ratios.

  1. Stable isotope evidence for shifting Mediterranean climatic influences in Western Romania, East-Central Europe

    NASA Astrophysics Data System (ADS)

    Perşoiu, Aurel; Viorica, Nagavciuc; Carmen, Bădăluţă

    2015-04-01

    The stable isotopic composition of oxygen and hydrogen in precipitation, preserved in various sedimentary archives (speleothems, cave ice, tree rings) is being intensively used to reconstruct past climatic variability in western Romania. These studies heavily rely on the assumption that air temperature is the main factor controlling the isotopic composition of precipitation and hence this climatic parameter is the one reconstructed. However, ongoing monitoring studies are increasingly showing that this, especially along Romania's western border, moisture source is playing an important role in determining the isotopic composition of precipitation, hence complicating the simplistic picture outlined above. One of the main factors influencing climate variability in Romania is the North Atlantic Oscillation (NAO), a measure of the strength of the Icelandic Low and Azores High. Over During the positive NAO phase, the Atlantic storms are displaced northward and, although reduced in strength, Mediterranean cyclones penetrate further north. During the negative phase however, the Atlantic storms track is displaced southward, restricting the area receiving Mediterranean precipitation to the SW corner of Romania. Here we present isotopic evidence for a shift in the source of precipitation from North Atlantic to Mediterranean ones in SW Romania that masks the temperature signal recorded in the stable isotopic composition of precipitation. Between April 2012 and 2014 we have collected monthly samples of precipitation along a N-S transect in Western Romania and have analyzed them for their δ18O and δ2H. Precipitation in NW Romania are derived solely from North Atlantic sources, while those in SW Romania mix moisture evaporated from both the North Atlantic and the Mediterranean Sea. The northern boundary of the Mediterranean influence is shifting in phase with the NAO index and the position of the jet-stream. As a result, during periods with high NAO index, the stable isotope

  2. Purdue Rare Isotope Measurement Laboratory

    NASA Astrophysics Data System (ADS)

    Caffee, M.; Elmore, D.; Granger, D.; Muzikar, P.

    2002-12-01

    The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is a dedicated research and service facility for accelerator mass spectrometry. AMS is an ultra-sensitive analytical technique used to measure low levels of long-lived cosmic-ray-produced and anthropogenic radionuclides, and rare trace elements. We measure 10Be (T1/2 = 1.5 My), 26Al (.702 My), 36Cl (.301 My), and 129I (16 My), in geologic samples. Applications include dating the cosmic-ray-exposure time of rocks on Earth's surface, determining rock and sediment burial ages, measuring the erosion rates of rocks and soils, and tracing and dating ground water. We perform sample preparation and separation chemistries for these radio-nuclides for our internal research activities and for those external researchers not possessing this capability. Our chemical preparation laboratories also serve as training sites for members of the geoscience community developing these techniques at their institutions. Research at Purdue involves collaborators among members of the Purdue Departments of Physics, Earth and Atmospheric Sciences, Chemistry, Agronomy, and Anthropology. We also collaborate and serve numerous scientists from other institutions. We are currently in the process of modernizing the facility with the goals of higher precision for routinely measured radio-nuclides, increased sample throughput, and the development of new measurement capabilities for the geoscience community.

  3. Measuring SNM Isotopic Distributions using FRAM

    SciTech Connect

    Geist, William H.

    2015-12-02

    The first group of slides provides background information on the isotopic composition of plutonium. It is shown that 240Pu is the critical isotope in neutron coincidence/multiplicity counting. Next, response function analysis to determine isotopic composition is discussed. The isotopic composition can be determined by measuring the net peak counts from each isotope and then taking the ratio of the counts for each isotope relative to the total counts for the element. Then FRAM (Fixed energy Response function Analysis with Multiple efficiencies) is explained. FRAM can control data acquisition, automatically analyze newly acquired data, analyze previously acquired data, provide information on the quality of the analysis, and facilitate analysis in unusual situations (non-standard energy calibrations, gamma rays from non-SNM isotopes, poor spectra (within limits)).

  4. Multiple linear regression for isotopic measurements

    NASA Astrophysics Data System (ADS)

    Garcia Alonso, J. I.

    2012-04-01

    There are two typical applications of isotopic measurements: the detection of natural variations in isotopic systems and the detection man-made variations using enriched isotopes as indicators. For both type of measurements accurate and precise isotope ratio measurements are required. For the so-called non-traditional stable isotopes, multicollector ICP-MS instruments are usually applied. In many cases, chemical separation procedures are required before accurate isotope measurements can be performed. The off-line separation of Rb and Sr or Nd and Sm is the classical procedure employed to eliminate isobaric interferences before multicollector ICP-MS measurement of Sr and Nd isotope ratios. Also, this procedure allows matrix separation for precise and accurate Sr and Nd isotope ratios to be obtained. In our laboratory we have evaluated the separation of Rb-Sr and Nd-Sm isobars by liquid chromatography and on-line multicollector ICP-MS detection. The combination of this chromatographic procedure with multiple linear regression of the raw chromatographic data resulted in Sr and Nd isotope ratios with precisions and accuracies typical of off-line sample preparation procedures. On the other hand, methods for the labelling of individual organisms (such as a given plant, fish or animal) are required for population studies. We have developed a dual isotope labelling procedure which can be unique for a given individual, can be inherited in living organisms and it is stable. The detection of the isotopic signature is based also on multiple linear regression. The labelling of fish and its detection in otoliths by Laser Ablation ICP-MS will be discussed using trout and salmon as examples. As a conclusion, isotope measurement procedures based on multiple linear regression can be a viable alternative in multicollector ICP-MS measurements.

  5. Shifting sediment sources in the world's longest river: A strontium isotope record for the Holocene Nile

    NASA Astrophysics Data System (ADS)

    Woodward, Jamie; Macklin, Mark; Fielding, Laura; Millar, Ian; Spencer, Neal; Welsby, Derek; Williams, Martin

    2015-12-01

    We have reconstructed long-term shifts in catchment sediment sources by analysing, for the first time, the strontium (Sr) and neodymium (Nd) isotope composition of dated floodplain deposits in the Desert Nile. The sediment load of the Nile has been dominated by material from the Ethiopian Highlands for much of the Holocene, but tributary wadis and aeolian sediments in Sudan and Egypt have also made major contributions to valley floor sedimentation. The importance of these sources has shifted dramatically in response to global climate changes. During the African Humid Period, before c. 4.5 ka, when stronger boreal summer insolation produced much higher rainfall across North Africa, the Nile floodplain in northern Sudan shows a tributary wadi input of 40-50%. Thousands of tributary wadis were active at this time along the full length of the Saharan Nile in Egypt and Sudan. As the climate became drier after 4.5 ka, the valley floor shows an abrupt fall in wadi inputs and a stronger Blue Nile/Atbara contribution. In the arid New Kingdom and later periods, in palaeochannel fills on the margins of the valley floor, aeolian sediments replace wadi inputs as the most important secondary contributor to floodplain sedimentation. Our sediment source data do not show a measurable contribution from the White Nile to the floodplain deposits of northern Sudan over the last 8500 years. This can be explained by the distinctive hydrology and sediment delivery dynamics of the upper Nile basin. High strontium isotope ratios observed in delta and offshore records - that were previously ascribed to a stronger White Nile input during the African Humid Period - may have to be at least partly reassessed. Our floodplain Sr records also have major implications for bioarchaeologists who carry out Sr isotope-based investigations of ancient human remains in the Nile Valley because the isotopic signature of Nile floodplain deposits has shifted significantly over time.

  6. The second spectrum of niobium: III. Evaluation of line isotope shifts

    NASA Astrophysics Data System (ADS)

    Bouazza, Safa

    2013-03-01

    Using isotope shift values of only one Nb II line, we propose for the first time to predict isotope shifts of all spectral lines for this ion for any pair of isotopes. For this purpose, we had recourse to ab intio calculations to determine specific mass and field shifts of all relevant Nb II configuration averages, which are respectively proportional to the Vinti integral k-factor and the charge density at the nucleus, 4л|Ψ(o)|2. With the help of very accurate level eigenvectors of these configurations and using the sharing rule, we computed specific mass and field shifts of each level. Since a transition wavenumber is the difference between two energy levels, we then deduced line isotope shifts.

  7. Detecting shifts in tropical moisture imbalances with satellite-derived isotope ratios in water vapor

    NASA Astrophysics Data System (ADS)

    Bailey, A.; Blossey, P. N.; Noone, D.; Nusbaumer, J.; Wood, R.

    2017-06-01

    As global temperatures rise, regional differences in evaporation (E) and precipitation (P) are likely to become more disparate, causing the drier E-dominated regions of the tropics to become drier and the wetter P-dominated regions to become wetter. Models suggest that such intensification of the water cycle should already be taking place; however, quantitatively verifying these changes is complicated by inherent difficulties in measuring E and P with sufficient spatial coverage and resolution. This paper presents a new metric for tracking changes in regional moisture imbalances (e.g., E-P) by defining δDq—the isotope ratio normalized to a reference water vapor concentration of 4 mmol mol-1—and evaluates its efficacy using both remote sensing retrievals and climate model simulations in the tropics. By normalizing the isotope ratio with respect to water vapor concentration, δDq isolates the portion of isotopic variability most closely associated with shifts between E- and P-dominated regimes. Composite differences in δDq between cold and warm phases of El Niño-Southern Oscillation (ENSO) verify that δDq effectively tracks changes in the hydrological cycle when large-scale convective reorganization takes place. Simulated δDq also demonstrates sensitivity to shorter-term variability in E-P at most tropical locations. Since the isotopic signal of E-P in free tropospheric water vapor transfers to the isotope ratios of precipitation, multidecadal observations of both water vapor and precipitation isotope ratios should provide key evidence of changes in regional moisture imbalances now and in the future.

  8. Accurate electron affinity of Pb and isotope shifts of binding energies of Pb(.).

    PubMed

    Chen, Xiaolin; Ning, Chuangang

    2016-08-28

    Lead (Pb) was the last element of the group IVA whose electron affinity had a low accuracy around 10 meV before the present work. This was due to the generic threshold photodetachment measurement that cannot extent well below 0.5 eV due to the light source limitation. In the present work, the electron affinity of Pb was determined to be 2877.33(13) cm(-1) or 0.356 743(16) eV for the isotope m = 208. The accuracy was improved by a factor of 500 with respect to the previous laser photodetachment electron spectroscopy. Moreover, remarkable isotope shifts of the binding energy of Pb(-) 6p(3) (4)S3/2 - Pb 6p(2) (3)P2 were observed for m = 206, 207, and 208.

  9. Accurate electron affinity of Pb and isotope shifts of binding energies of Pb-

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolin; Ning, Chuangang

    2016-08-01

    Lead (Pb) was the last element of the group IVA whose electron affinity had a low accuracy around 10 meV before the present work. This was due to the generic threshold photodetachment measurement that cannot extent well below 0.5 eV due to the light source limitation. In the present work, the electron affinity of Pb was determined to be 2877.33(13) cm-1 or 0.356 743(16) eV for the isotope m = 208. The accuracy was improved by a factor of 500 with respect to the previous laser photodetachment electron spectroscopy. Moreover, remarkable isotope shifts of the binding energy of Pb- 6p3 4S3/2 - Pb 6p2 3P2 were observed for m = 206, 207, and 208.

  10. Effect of realistic nuclear charge distributions on isotope shifts and progress towards the extraction of higher-order nuclear radial moments

    NASA Astrophysics Data System (ADS)

    Papoulia, A.; Carlsson, B. G.; Ekman, J.

    2016-10-01

    Atomic spectral lines from different isotopes display a small shift in energy, commonly referred to as the line isotope shift. One of the components of the isotope shift is the field shift, which depends on the extent and the shape of the nuclear charge density distribution. The purpose of this work is to investigate how sensitive field shifts are with respect to variations in the nuclear size and shape and what information of nuclear charge distributions can be extracted from measurements. Nuclear properties are obtained from nuclear density functional theory calculations based on the Skyrme-Hartree-Fock-Bogoliubov approach. These results are combined with multiconfiguration Dirac-Hartree-Fock methods to obtain realistic field shifts and it is seen that phenomena such as nuclear deformation and variations in the diffuseness of nuclear charge distributions give measurable contributions to the isotope shifts. Using a different approach, we demonstrate the possibility to extract information concerning the nuclear charge densities from the observed field shifts. We deduce that combining methods used in atomic and nuclear structure theory gives an improved description of field shifts and that extracting additional nuclear information from measured isotope shifts is possible in the near future with improved experimental methods.

  11. Feasibility of Isotopic Measurements: Graphite Isotopic Ratio Method

    SciTech Connect

    Wood, Thomas W.; Gerlach, David C.; Reid, Bruce D.; Morgan, W. C.

    2001-04-30

    This report addresses the feasibility of the laboratory measurements of isotopic ratios for selected trace constituents in irradiated nuclear-grade graphite, based on the results of a proof-of-principal experiment completed at Pacific Northwest National Laboratory (PNNL) in 1994. The estimation of graphite fluence through measurement of isotopic ratio changes in the impurity elements in the nuclear-grade graphite is referred to as the Graphite Isotope Ratio Method (GIRM). Combined with reactor core and fuel information, GIRM measurements can be employed to estimate cumulative materials production in graphite moderated reactors. This report documents the laboratory procedures and results from the initial measurements of irradiated graphite samples. The irradiated graphite samples were obtained from the C Reactor (one of several production reactors at Hanford) and from the French G-2 Reactor located at Marcoule. Analysis of the irradiated graphite samples indicated that replicable measurements of isotope ratios could be obtained from the fluence sensitive elements of Ti, Ca, Sr, and Ba. While these impurity elements are present in the nuclear-grade graphite in very low concentrations, measurement precision was typically on the order of a few tenths of a percent to just over 1 percent. Replicability of the measurements was also very good with measured values differing by less than 0.5 percent. The overall results of this initial proof-of-principal experiment are sufficiently encouraging that a demonstration of GIRM on a reactor scale basis is planned for FY-95.

  12. Stable Isotopic Shifts in Fish Bones from Multiple Archeological Coastal Middens in Penobscot Bay, Maine

    NASA Astrophysics Data System (ADS)

    Harris, C.; Johnson, B.; Ambrose, W. G.; Bourque, B.; Dostie, P.; Crowley, E.

    2010-12-01

    The carbon and nitrogen stable isotope compositions of collagen extracted from well-preserved archeological fish bones has the potential to provide useful information on fish diets and food web dynamics over time. Previous work on the Turner Farm archaeological site in Penobscot Bay, Gulf of Maine, reveals significant shifts in fish diets have occurred since European colonization (post 1620’s). The objective of the present study was to analyze samples from other archaeological sites within Penobscot Bay to characterize the spatial extent of the isotopic shift measured at Turner Farm. Stratified cod, flounder, and sculpin bones were analyzed from eight coastal middens located approximately 50km apart from one another within Penobscot Bay. The bones were sampled from three time horizons (0kya, 0.5-1kya, and 2.2-2.4kya). All bone samples were demineralized in 0.2M HCl at 4°C for 2 to 7 days and then extracted in 0.25M NaOH at 4°C for 1 to 2 hours. After freeze-drying, the bulk isotopic composition of each sample was analyzed using the EA-IRMS. In all stratigraphic horizons analyzed, cod were more enriched in δ13C and δ15N than sculpin, and flounder were the most depleted in δ13C and δ15N . However, the isotopic offsets between the fish species decreased from 2.4kya to the present. The nitrogen isotope composition was relatively constant over time and space for all species, implying that trophic levels for the fishes analyzed have not changed significantly in Penobscot Bay for the last 2,400 years. The carbon isotope composition also appears to be constant spatially in Penobscot Bay, however, the modern signal was more depleted than the paleo signal in all three species. The difference between the modern and paleo δ13C is ~5‰ for cod and flounder, and ~9‰ for sculpin. These shifts may, in part, be explained by decreases in both primary producer and prey species diversity, as kelp forests replace eelgrass beds in the Gulf of Maine.

  13. Relativistic calculations of the isotope shifts in highly charged Li-like ions

    NASA Astrophysics Data System (ADS)

    Zubova, N. A.; Kozhedub, Y. S.; Shabaev, V. M.; Tupitsyn, I. I.; Volotka, A. V.; Plunien, G.; Brandau, C.; Stöhlker, Th.

    2014-12-01

    Relativistic calculations of the isotope shifts of energy levels in highly charged Li-like ions are performed. The nuclear recoil (mass shift) contributions are calculated by merging the perturbative and large-scale configuration-interaction Dirac-Fock-Sturm (CI-DFS) methods. The nuclear size (field shift) contributions are evaluated by the CI-DFS method including the electron-correlation, Breit, and QED corrections. The nuclear deformation and nuclear polarization corrections to the isotope shifts in Li-like neodymium, thorium, and uranium are also considered. The results of the calculations are compared with the theoretical values obtained with other methods.

  14. Progress in speckle-shift strain measurement

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.; Barranger, John P.; Oberle, Lawrence G.; Greer, Lawrence C., III

    1991-01-01

    The Instrumentation and Control Technology Division of the Lewis Research Center has been developing an in-house capability to make one dimensional and two dimensional optical strain measurements on high temperature test specimens. The measurements are based on a two-beam speckle-shift technique. The development of composite materials for use in high temperature applications is generating interest in using the speckle-shift technique to measure strains on small diameter fibers and wires of various compositions. The results of preliminary speckle correlation tests on wire and fiber specimens are covered, and the advanced system currently under development is described.

  15. Observation of the (162)Dy-(164)Dy Isotope Shift for the 0 → 16 717.79 cm(-1) Optical Transition.

    PubMed

    Nardin Barreta, Luiz Felipe; Victor, Alessandro Rogério; Bueno, Patrícia; Dos Santos, Jhonatha Ricardo; da Silveira, Carlos Alberto Barbosa; Neri, José Wilson; Neto, Jonas Jakutis; Sbampato, Maria Esther; Destro, Marcelo Geraldo

    2017-08-01

    In this work, we report a newly observed isotope shift between (162)Dy and (164)Dy isotopes for the 0 → 16 717.79 cm(-1) (598.003 nm) optical transition. We compared the newly observed results against two other lines (597.452 nm and 598.859 nm), which we measured in this work, and were already reported in the literature. The newly observed 162-164 Dy isotope shift, shows at least a 20% larger isotope shift than the isotope shifts for the other two lines investigated. The larger 162-164 isotope shift observed for the 598.003 nm line could lead to an increased isotope selectivity for atomic vapor laser isotope separation (AVLIS). Hence, this line could be a good choice for application in AVLIS. Experimental data available in the literature for the 597.452 nm and 598.859 nm lines, enabled us to perform simulations of spectra for both lines, in order to confirm the accuracy of our experimental measurements.

  16. Attogram measurement of rare isotopes by CW resonance ionization mass spectrometry

    SciTech Connect

    Bushaw, B.A.

    1992-05-01

    Three-color double-resonance ionization mass spectrometry, using two single-frequency cw dye lasers and a cw carbon dioxide laser, has been applied to the detection of attogram quantities of rare radionuclides. {sup 210}Pb has been measured in human hair and brain tissue samples to assess indoor radon exposure. Measurements on {sup 90}Sr have shown overall isotopic selectivity of greater than 10{sup 9} despite unfavorable isotope shifts relative to the major stable isotope, {sup 88}Sr.

  17. Attogram measurement of rare isotopes by CW resonance ionization mass spectrometry

    SciTech Connect

    Bushaw, B.A.

    1992-05-01

    Three-color double-resonance ionization mass spectrometry, using two single-frequency cw dye lasers and a cw carbon dioxide laser, has been applied to the detection of attogram quantities of rare radionuclides. {sup 210}Pb has been measured in human hair and brain tissue samples to assess indoor radon exposure. Measurements on {sup 90}Sr have shown overall isotopic selectivity of greater than 10{sup 9} despite unfavorable isotope shifts relative to the major stable isotope, {sup 88}Sr.

  18. Baseline shifts in coral skeletal oxygen isotopic composition: a signature of symbiont shuffling?

    NASA Astrophysics Data System (ADS)

    Carilli, J. E.; Charles, C. D.; Garren, M.; McField, M.; Norris, R. D.

    2013-06-01

    Decades-long records of the stable isotopic composition of coral skeletal cores were analyzed from four sites on the Mesoamerican Reef. Two of the sites exhibited baseline shifts in oxygen isotopic composition after known coral bleaching events. Changes in pH at the calcification site caused by a change in the associated symbiont community are invoked to explain the observed shift in the isotopic composition. To test the hypothesis that changes in symbiont clade could affect skeletal chemistry, additional coral samples were collected from Belize for paired Symbiodinium identification and skeletal stable isotopic analysis. We found some evidence that skeletal stable isotopic composition may be affected by symbiont clade and suggest this is an important topic for future investigation. If different Symbiodinium clades leave consistent signatures in skeletal geochemical composition, the signature will provide a method to quantify past symbiont shuffling events, important for understanding how corals are likely to respond to climate change.

  19. Isotope effects on chemical shifts in the study of intramolecular hydrogen bonds.

    PubMed

    Hansen, Poul Erik

    2015-01-30

    The paper deals with the use of isotope effects on chemical shifts in characterizing intramolecular hydrogen bonds. Both so-called resonance-assisted (RAHB) and non-RAHB systems are treated. The importance of RAHB will be discussed. Another very important issue is the borderline between "static" and tautomeric systems. Isotope effects on chemical shifts are particularly useful in such studies. All kinds of intramolecular hydrogen bonded systems will be treated, typical hydrogen bond donors: OH, NH, SH and NH+, typical acceptors C=O, C=N, C=S C=N-. The paper will be deal with both secondary and primary isotope effects on chemical shifts. These two types of isotope effects monitor the same hydrogen bond, but from different angles.

  20. Shifting material source of Chinese loess since ~2.7 Ma reflected by Sr isotopic composition

    PubMed Central

    Zhang, Wenfang; Chen, Jun; Li, Gaojun

    2015-01-01

    Deciphering the sources of eolian dust on the Chinese Loess Plateau (CLP) is fundamental to reconstruct paleo-wind patterns and paleo-environmental changes. Existing datasets show contradictory source evolutions of eolian dust on the CLP, both on orbital and tectonic timescales. Here, the silicate Sr and Nd isotopic compositions of a restricted grain size fraction (28–45 μm) were measured to trace the source evolution of the CLP since ~2.7 Ma. Our results revealed an unchanged source on orbital timescales but a gradual source shift from the Qilian Mountains to the Gobi Altay Mountains during the past 2.7 Ma. Both tectonic uplift and climate change may have played important roles for this shift. The later uplift of the Gobi Altay Mountains relative to the Qilian Mountains since 5 ± 3 Ma might be responsible for the increasing contribution of Gobi materials to the source deserts in Alxa arid lands. Enhanced winter monsoon may also facilitate transportation of Gobi materials from the Alxa arid lands to the CLP. The shifting source of Asian dust was also reflected in north Pacific sediments. The finding of this shifting source calls for caution when interpreting the long-term climate changes based on the source-sensitive proxies of the eolian deposits. PMID:25996645

  1. Isotope shift of the thallium (6s6p2) 4P1/2 state

    NASA Astrophysics Data System (ADS)

    Wynar, R. H.; Iinuma, M.; Nagourney, W.; Fortson, E. N.

    2003-09-01

    We have measured the hyperfine splitting and level isotope shifts (LIS) of the (6s6p2) 4P1/2 level of 205Tl and 203Tl using laser absorption spectroscopy in a thallium oven near 1373 K. We determine that the hyperfine splitting between the F=1 and 0 levels of the 4P1/2 state in 205Tl is 75.179±0.087 GHz. The F=0 LIS is -7.333±0.025 GHz and the F=1 LIS is -6.500±0.030 GHz, with the 205Tl level below the 203Tl level in both cases. We use our results together with other data to analyze the configuration mixing of the 4P1/2 state with the nearby (6s210s) 2S1/2 state. The mixing inferred from the hyperfine results is consistent with that inferred from the isotope shift results.

  2. Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances

    DOEpatents

    Harney, Robert C.; Bloom, Stewart D.

    1978-01-01

    Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances.

  3. Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur

    USGS Publications Warehouse

    McCutchan, J.H.; Lewis, W.M.; Kendall, C.; McGrath, C.C.

    2003-01-01

    Use of stable isotope ratios to trace pathways of organic matter among consumers requires knowledge of the isotopic shift between diet and consumer. Variation in trophic shift among consumers can be substantial. For data from the published literature and supplementary original data (excluding fluid-feeding consumers), the mean isotopic shift for C was +0.5 ?? 0.13??? rather than 0.0???, as commonly assumed. The shift for C was higher for consumers analyzed as muscle (+1.3 ?? 0.30???) than for consumers analyzed whole (+0.3 ?? 0.14???). Among consumers analyzed whole, the trophic shift for C was lower for consumers acidified prior to analysis (-0.2 ?? 0.21???) than for unacidified samples (+0.5 ?? 0.17???). For N, trophic shift was lower for consumers raised on invertebrate diets (+1.4 ?? 0.21???) than for consumers raised on other high-protein diets (+3.3 ?? 0.26???) and was intermediate for consumers raised on plant and algal diets (+2.2 ?? 0.30???). The trophic shift for S differed between high-protein (+2.0 ?? 0.65???) and low-protein diets (-0.5 ?? 0.56???). Thus, methods of analysis and dietary differences can affect trophic shift for consumers; the utility of stable isotope methods can be improved if this information is incorporated into studies of trophic relationships. Although few studies of stable isotope ratios have considered variation in the trophic shift, such variation is important because small errors in estimates of trophic shift can result in large errors in estimates of the contribution of sources to consumers or in estimates of trophic position.

  4. Strontium isotopes provide clues for a process shift in base cation dynamics in young volcanic soils

    NASA Astrophysics Data System (ADS)

    Bingham, N.; Jackson, M. G.; Bookhagen, B.; Maher, K.; Chadwick, O.

    2015-12-01

    Despite advances in soil development theory based on studies of old soils or over long timescales, little is known about soil thresholds (dramatic changes in soil properties associated with only small shifts in external forcing factors) that might be expressed in young soils (less than 10 kyr). Therefore, we seek to understand infant soil development in a tropical environment through the sourcing of plant available base cations by measuring the strontium (Sr) isotopic composition of the soil exchange complex. Our sampling strategy spans soils in three different precipitation ranges (950-1060 mm, 1180-1210 mm, and 1450-1500) and an array of soil ages from 500 to 7500 years in the Kona region on the island of Hawaii. In Hawaiian soils, 87Sr/86Sr values are determined by a mixture of three components: a mantle-derived component from the lava (0.7034), a rainfall component (0.7093) and a component from continental dust (0.720). Elevation-controlled leaching intensity in the wettest localities produces a decline in the concentration of base cations supplied by basalt and a dilute resupply by rainfall. In the driest sites, where leaching intensity is dramatically reduced, there is a buildup of rainfall-derived extractable Sr in the soil over time. Slow rock weathering rates produce a small rock-derived cation input to the soil. Thus, Sr isotope signatures reflect both the input of rainfall-derived cations and rock-derived cations with values that fall between rainfall and basaltic signatures. Soils in the intermediate precipitation range have Sr isotopic signatures consistent with both the wet and dry trends; suggesting that they lie close to the critical precipitation amount that marks a shift between these two processes. For the Kona region, this transition seems to occur at 1200 mm /yr. In contrast to the clear-cut differentiation in strontium isotopes with precipitation shifts observed in older soils, patterns on these young soils in Kona are complicated by low soil

  5. Carbon and Nitrogen Isotopes from Top Predator Amino Acids Reveal Rapidly Shifting Ocean Biochemistry in the Outer California Current

    PubMed Central

    Ruiz-Cooley, Rocio I.; Koch, Paul L.; Fiedler, Paul C.; McCarthy, Matthew D.

    2014-01-01

    Climatic variation alters biochemical and ecological processes, but it is difficult both to quantify the magnitude of such changes, and to differentiate long-term shifts from inter-annual variability. Here, we simultaneously quantify decade-scale isotopic variability at the lowest and highest trophic positions in the offshore California Current System (CCS) by measuring δ15N and δ13C values of amino acids in a top predator, the sperm whale (Physeter macrocephalus). Using a time series of skin tissue samples as a biological archive, isotopic records from individual amino acids (AAs) can reveal the proximate factors driving a temporal decline we observed in bulk isotope values (a decline of ≥1 ‰) by decoupling changes in primary producer isotope values from those linked to the trophic position of this toothed whale. A continuous decline in baseline (i.e., primary producer) δ15N and δ13C values was observed from 1993 to 2005 (a decrease of ∼4‰ for δ15N source-AAs and 3‰ for δ13C essential-AAs), while the trophic position of whales was variable over time and it did not exhibit directional trends. The baseline δ15N and δ13C shifts suggest rapid ongoing changes in the carbon and nitrogen biogeochemical cycling in the offshore CCS, potentially occurring at faster rates than long-term shifts observed elsewhere in the Pacific. While the mechanisms forcing these biogeochemical shifts remain to be determined, our data suggest possible links to natural climate variability, and also corresponding shifts in surface nutrient availability. Our study demonstrates that isotopic analysis of individual amino acids from a top marine mammal predator can be a powerful new approach to reconstructing temporal variation in both biochemical cycling and trophic structure. PMID:25329915

  6. Carbon and nitrogen isotopes from top predator amino acids reveal rapidly shifting ocean biochemistry in the outer California Current.

    PubMed

    Ruiz-Cooley, Rocio I; Koch, Paul L; Fiedler, Paul C; McCarthy, Matthew D

    2014-01-01

    Climatic variation alters biochemical and ecological processes, but it is difficult both to quantify the magnitude of such changes, and to differentiate long-term shifts from inter-annual variability. Here, we simultaneously quantify decade-scale isotopic variability at the lowest and highest trophic positions in the offshore California Current System (CCS) by measuring δ15N and δ13C values of amino acids in a top predator, the sperm whale (Physeter macrocephalus). Using a time series of skin tissue samples as a biological archive, isotopic records from individual amino acids (AAs) can reveal the proximate factors driving a temporal decline we observed in bulk isotope values (a decline of ≥1 ‰) by decoupling changes in primary producer isotope values from those linked to the trophic position of this toothed whale. A continuous decline in baseline (i.e., primary producer) δ15N and δ13C values was observed from 1993 to 2005 (a decrease of ∼4‰ for δ15N source-AAs and 3‰ for δ13C essential-AAs), while the trophic position of whales was variable over time and it did not exhibit directional trends. The baseline δ15N and δ13C shifts suggest rapid ongoing changes in the carbon and nitrogen biogeochemical cycling in the offshore CCS, potentially occurring at faster rates than long-term shifts observed elsewhere in the Pacific. While the mechanisms forcing these biogeochemical shifts remain to be determined, our data suggest possible links to natural climate variability, and also corresponding shifts in surface nutrient availability. Our study demonstrates that isotopic analysis of individual amino acids from a top marine mammal predator can be a powerful new approach to reconstructing temporal variation in both biochemical cycling and trophic structure.

  7. Isotope shift and hyperfine structure in the atomic spectrum of hafnium by laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Zimmermann, D.; Baumann, P.; Kuszner, D.; Werner, A.

    1994-08-01

    The isotope shift and the hyperfine structure of 14 spectral lines of Hf i were investigated using high-resolution laser spectroscopy of a well-collimated beam of Hf atoms. The hyperfine splitting constants A and B of the electronic states 5G5,...,5G2,5F3 of the excited configuration 5d26s6p and of some electronic states of 5d6s26p were obtained for the two stable odd isotopes 177Hf and 179Hf. From these data one-electron hyperfine splitting parameters could be deduced, e.g., a6s=3.08(15) GHz for the magnetic dipole part in the case of 177Hf. Our accurate experimental values of the isotope shifts between the stable Hf isotopes 174, 176-180 allow a reliable separation of the effect of the specific mass shift and of the field shift for all observed spectral lines. Using the field shift of the 545.29-nm line, which corresponds to an almost pure 5d26s2-5d26s6p transition, the change in mean-square nuclear charge radius between 178Hf and 180Hf was determined to be δ=0.098(13) fm2. Values of δ for the Hf isotopes 174, 176, 177, and 179 referred to 178Hf are also available from the present work.

  8. Isotopic Differences in CO Air Broadening and Shift Parameters

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  9. Deuterium isotope effect on 13C chemical shifts of tetrabutylammonium salts of Schiff bases amino acids.

    PubMed

    Rozwadowski, Z

    2006-09-01

    Deuterium isotope effects on 13C chemical shift of tetrabutylammonium salts of Schiff bases, derivatives of amino acids (glycine, L-alanine, L-phenylalanine, L-valine, L-leucine, L-isoleucine and L-methionine) and various ortho-hydroxyaldehydes in CDCl3 have been measured. The results have shown that the tetrabutylammonium salts of the Schiff bases amino acids, being derivatives of 2-hydroxynaphthaldehyde and 3,5-dibromosalicylaldehyde, exist in the NH-form, while in the derivatives of salicylaldehyde and 5-bromosalicylaldehyde a proton transfer takes place. The interactions between COO- and NH groups stabilize the proton-transferred form through a bifurcated intramolecular hydrogen bond. Copyright (c) 2006 John Wiley & Sons, Ltd.

  10. Re-investigating the isotopic fractionation corrections in radiocarbon measurements

    NASA Astrophysics Data System (ADS)

    Fahrni, S.; Santos, G. M.; Xu, X.; Southon, J. R.

    2012-12-01

    By convention (Stuiver and Polach, 1977), 14C data has to be corrected for any isotopic fractionation occurring in nature, during the sample preparation or the measurement. The fractionation factor b = 2.0 used to correct the 14C/12C ratio for shifts in the 13C/12C ratio has been proposed in 1954 (Craig, 1954) and has been applied ever since. While theoretical considerations have suggested moderate deviations of b from 2.0, some measurements have suggested larger differences (e.g. Saliege and Fontes, 1984). With the increasing precision of radiocarbon measurements, potential deviations of b from 2.0 become more significant, since these could cause shifts of several decades in some radiocarbon dates (Southon, 2011). It is therefore of great interest for the radiocarbon community to re-evaluate the fractionation corrections. We present approaches for the experimental determination of b and discuss results and their effects on radiocarbon dating. Stuiver M., Polach H.A., 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355-63. Saliege J.F., Fontes J.C., 1984. Essai de détermination expérimentale du fractionnement des isotopes 13C et 14C du carbone au cours de processus naturels. International Journal of Applied Radiation and Isotopes 35(1):55-62. Craig H., 1954. Carbon 13 in plants and the relationships between carbon 13 and carbon 14 in nature. Journal of Geology 62(2):115-49. Southon J., 2011. Are the Fractionation Corrections Correct: Are the Isotopic Shifts for 14C/12C Ratios in Physical Processes and Chemical Reactions Really Twice Those for 13C/12C? Radiocarbon 53(4):691-704.

  11. Isotopic ratio measurements with ICP-MS

    SciTech Connect

    Russ, G.P. III; Bazan, J.M.

    1986-06-03

    An inductively-coupled-plasma source mass spectrometer (ICP-MS) has been used to measure the isotopic composition of U, Pb, Os, and B standards. Particular emphasis has been placed on uranium because of its nuclear and environmental interest and because of the availability of a well-characterized set of standards with a wide range of isotopic compositions. The precision and accuracy obtainable in isotope ratio measurements by ICP-MS depend on many factors including background, interferences, dead time, mass fractionation (bias), abundance sensitivity, and counting statistics. Which, if any, of these factors controls accuracy and precision depends on the type of sample being analyzed and the characteristics of the mass spectrometer. These issues are discussed in detail.

  12. J dependences of the isotope shift and hyperfine structure in the Sm i 4f65d6s 9H term

    NASA Astrophysics Data System (ADS)

    Jin, W. G.; Horiguchi, T.; Yang, W.; Endo, I.

    1994-06-01

    Isotope shifts and hyperfine structures of twelve transitions from the high-lying metastable 9HJ (J=1-7) states of the 4f65d6s configuration in Sm i have been measured for the stable isotopes by means of atomic-beam laser spectroscopy. Hyperfine constants A and B for the odd-mass isotopes 147Sm and 149Sm are determined for the 9HJ (J=1-7) states and six upper levels of the transitions in Sm i. $J- dependences of the isotope shifts are observed for the 4f65d6s 9H term. Parameters z5d of the crossed-second-order effect are derived for the 4f65d6s configuration, and z5d/λ is found to be 165(10) MHz/fm2. It has been verified that the field shift is dominant in the crossed-second-order effect.

  13. Dietary back-calculation using stable isotopes: can activities of enzymes involved in amino acid metabolism be used to improve estimates of trophic shifts in fish?

    PubMed

    Gaye-Siessegger, Julia; Focken, Ulfert; Abel, Hansjörg; Becker, Klaus

    2007-06-01

    The aim of this study was (1) to assess the effects of dietary protein content and feeding level on trophic shifts of C and N isotopes (Delta delta(13)C(tissue-diet) and Delta delta(15)N(tissue-diet)) and (2) to test whether the measurement of the activities of two enzymes involved in the metabolism of amino acids could improve the accuracy of estimation of the trophic shifts of C and N isotopes. For this, 36 Nile tilapia (Oreochromis niloticus) were kept under controlled conditions for 8 weeks and fed at three different levels (2, 4 and 8 g kg(-0.8) d(-1)) with three diets differing in their protein content only (20, 29 and 39 %). For each fish, food to fish body trophic shifts of C and N isotopes were measured as well as the hepatic activities of aspartate aminotransferase (ASAT) and glutamate dehydrogenase (GDH). The feeding level affected the activities of ASAT and GDH as well as the trophic shifts of C and N isotopes significantly but the dietary protein content had no significant effect except on the specific activity of ASAT. Fish fed at the lowest level had significantly higher trophic shifts of C and N isotopes than fish fed at higher levels. The trophic shifts were significantly lower in fish with a high protein utilisation. Values of the 'goodness-of-fit' for linear regressions between enzyme activities and trophic shifts were low. Thus, activities of ASAT and GDH are not suitable for predicting estimates of trophic shifts in situations where the amount of food consumed or the dietary protein content is not known. In further studies, activities of enzymes involved in the metabolism of amino acids combined with measurements of the activities of other enzymes should be used to try and improve the accuracy of estimates of trophic shifts.

  14. Nitrogen stable isotopes reveal age-dependent dietary shift in the Japanese scallop Mizuhopecten yessoensis.

    PubMed

    Aya, Frolan A; Kudo, Isao

    2017-03-01

    Ontogenetic niche shifts in diet are a consequence of changes in body size or resource partitioning between age classes. To better resolve the feeding patterns of the Japanese scallop Mizuhopecten yessoensis, we examined the relative importance of age and size in the diet of this species using stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) from 2006 to 2009. Contribution of food sources was quantified using an isotope mixing model by comparing the muscle tissue isotope ratios to those of suspended particulate organic matter (SPOM) and their zooplankton prey (e.g. micro- and meso-zooplankton). Unlike the δ(13)C values, which remained constant with age and size, muscle δ(15)N values were more positively correlated with age accounting for 69 % of variations than size with only 46 %. Increasing (15)N values with age suggested that shifts in diet from SPOM to micro- and meso-zooplankton occurred during ontogeny in M. yessoensis. Results of the isotope mixing model indicated that SPOM contribution to scallop's diet decreased from 68 to 8 % while those of zooplankton increased from 15 to 50 % with increasing age. This study concludes that age-related dietary shift explains the enrichment of (15)N, as a result of predation on zooplankton by M. yessoensis.

  15. BENCHMARKING ORTEC ISOTOPIC MEASUREMENTS AND CALCULATIONS

    SciTech Connect

    Dewberry, R; Raymond Sigg, R; Vito Casella, V; Nitin Bhatt, N

    2008-09-29

    This report represents a description of compiled benchmark tests conducted to probe and to demonstrate the extensive utility of the Ortec ISOTOPIC {gamma}-ray analysis computer program. The ISOTOPIC program performs analyses of {gamma}-ray spectra applied to specific acquisition configurations in order to apply finite-geometry correction factors and sample-matrix-container photon absorption correction factors. The analysis program provides an extensive set of preset acquisition configurations to which the user can add relevant parameters in order to build the geometry and absorption correction factors that the program determines from calculus and from nuclear g-ray absorption and scatter data. The Analytical Development Section field nuclear measurement group of the Savannah River National Laboratory uses the Ortec ISOTOPIC analysis program extensively for analyses of solid waste and process holdup applied to passive {gamma}-ray acquisitions. Frequently the results of these {gamma}-ray acquisitions and analyses are to determine compliance with facility criticality safety guidelines. Another use of results is to designate 55-gallon drum solid waste as qualified TRU waste3 or as low-level waste. Other examples of the application of the ISOTOPIC analysis technique to passive {gamma}-ray acquisitions include analyses of standard waste box items and unique solid waste configurations. In many passive {gamma}-ray acquisition circumstances the container and sample have sufficient density that the calculated energy-dependent transmission correction factors have intrinsic uncertainties in the range 15%-100%. This is frequently the case when assaying 55-gallon drums of solid waste with masses of up to 400 kg and when assaying solid waste in extensive unique containers. Often an accurate assay of the transuranic content of these containers is not required, but rather a good defensible designation as >100 nCi/g (TRU waste) or <100 nCi/g (low level solid waste) is required. In

  16. Hyperfine structure and isotope-shift investigations of atomic nitrogen by saturation spectroscopy

    NASA Astrophysics Data System (ADS)

    Cangiano, P.; de Angelis, M.; Gianfrani, L.; Pesce, G.; Sasso, A.

    1994-08-01

    In this work we report a Doppler-free investigation of atomic nitrogen. As a laser source we used a narrow-band semiconductor diode laser emitting in the near infrared. Atomic nitrogen was produced by dissociating N2 molecules in a radio-frequency discharge sustained by helium as a buffer gas. Hyperfine structures and isotope shifts of the transitions 3p 4P1/2-5/2-3s 4Po1/2-5/2 were investigated for the two stable isotopes 14N and 15N by using absorption-saturated laser spectroscopy.

  17. Carbon stable isotopic composition of soluble sugars in Tillandsia epiphytes varies in response to shifts in habitat.

    PubMed

    Goode, Laurel K; Erhardt, Erik B; Santiago, Louis S; Allen, Michael F

    2010-07-01

    We studied C stable isotopic composition (delta(13)C) of bulk leaf tissue and extracted sugars of four epiphytic Tillandsia species to investigate flexibility in the use of crassulacean acid metabolism (CAM) and C(3) photosynthetic pathways. Plants growing in two seasonally dry tropical forest reserves in Mexico that differ in annual precipitation were measured during wet and dry seasons, and among secondary, mature, and wetland forest types within each site. Dry season sugars were more enriched in (13)C than wet season sugars, but there was no seasonal difference in bulk tissues. Bulk tissue delta(13)C differed by species and by forest type, with values from open-canopied wetlands more enriched in (13)C than mature or secondary forest types. The shifts within forest habitat were related to temporal and spatial changes in vapor pressure deficits (VPD). Modeling results estimate a possible 4% increase in the proportional contribution of the C(3) pathway during the wet season, emphasizing that any seasonal or habitat-mediated variation in photosynthetic pathway appears to be quite moderate and within the range of isotopic effects caused by variation in stomatal conductance during assimilation through the C(3) pathway and environmental variation in VPD. C isotopic analysis of sugars together with bulk leaf tissue offers a useful approach for incorporating short- and long-term measurements of C isotope discrimination during photosynthesis.

  18. Carbon stable isotopic composition of soluble sugars in Tillandsia epiphytes varies in response to shifts in habitat

    PubMed Central

    Erhardt, Erik B.; Santiago, Louis S.; Allen, Michael F.

    2010-01-01

    We studied C stable isotopic composition (δ13C) of bulk leaf tissue and extracted sugars of four epiphytic Tillandsia species to investigate flexibility in the use of crassulacean acid metabolism (CAM) and C3 photosynthetic pathways. Plants growing in two seasonally dry tropical forest reserves in Mexico that differ in annual precipitation were measured during wet and dry seasons, and among secondary, mature, and wetland forest types within each site. Dry season sugars were more enriched in 13C than wet season sugars, but there was no seasonal difference in bulk tissues. Bulk tissue δ13C differed by species and by forest type, with values from open-canopied wetlands more enriched in 13C than mature or secondary forest types. The shifts within forest habitat were related to temporal and spatial changes in vapor pressure deficits (VPD). Modeling results estimate a possible 4% increase in the proportional contribution of the C3 pathway during the wet season, emphasizing that any seasonal or habitat-mediated variation in photosynthetic pathway appears to be quite moderate and within the range of isotopic effects caused by variation in stomatal conductance during assimilation through the C3 pathway and environmental variation in VPD. C isotopic analysis of sugars together with bulk leaf tissue offers a useful approach for incorporating short- and long-term measurements of C isotope discrimination during photosynthesis. PMID:20155286

  19. Isotope shift of 40,42,44,48Ca in the 4s 2S1/2 → 4p 2P3/2 transition

    NASA Astrophysics Data System (ADS)

    Gorges, C.; Blaum, K.; Frömmgen, N.; Geppert, Ch; Hammen, M.; Kaufmann, S.; Krämer, J.; Krieger, A.; Neugart, R.; Sánchez, R.; Nörtershäuser, W.

    2015-12-01

    We report on improved isotope shift measurements of the isotopes {}{40,42,{44,48}}Ca in the 4{{s}}{ }2{{{S}}}1/2\\to 4{{p}}{ }2{{{P}}}3/2 (D2) transition using collinear laser spectroscopy. Accurately known isotope shifts in the 4{{s}}{ }2{{{S}}}1/2\\to 4{{p}}{ }2{{{P}}}1/2(D1) transition were used to calibrate the ion beam energy with an uncertainty of {{Δ }}U≈ +/- 0.25 {{V}}. The accuracy in the D2 transition was improved by a factor of 5-10. A King-plot analysis of the two transitions revealed that the field shift factor in the D2 line is about 1.8(13)% larger than in the D1 transition which is ascribed to relativistic contributions of the 4{{{p}}}1/2 wave function.

  20. A possible isotope shift in the spectrum of a diffuse interstellar band

    NASA Astrophysics Data System (ADS)

    Webster, Adrian

    1996-10-01

    The regular series of peaks observed in the spectrum of the diffuse interstellar absorption band at 6614Angstroms is interpreted in terms of an isotope shift. It is supposed that the band is an electronic transition of some carbon-rich molecular species in the gaseous phase; that the electronic transition is accompanied by a simultaneous change in the vibrational state; and that the isotope shift is inertial, the consequence of the dependence of the vibrational frequency on the extent to which the more abundant ^12C atoms in the molecule are replaced by the more massive ^13C. A model is presented in which each isotopic variety of the molecule gives rise to a narrow absorption feature, the central wavelength of which is shifted by an amount proportional to the number of ^13C atoms in the molecule, and the intensity of which is given by the Poisson law governing the relative abundance of different isotopic varieties. The resulting synthetic spectrum resembles the observed spectrum most closely when the parameters of the model are given values appropriate to a molecule containing something like 30-100 carbon atoms. The sharpness of the peaks in the spectrum of lambda6614 implies that the molecule may have a high symmetry, of a kind to be found in cyclic polyynes, in fullerenes such as the soccer-ball molecule C_60 and in some of the derivatives such as the fulleranes C_60H_m, but not in linear polyynes or in planar molecules such as polycyclic aromatic hydrocarbons. The isotope shift is capable of producing a variety of band profiles, but gives rise to asymmetric profiles with extended blue wings only when the molecule is already vibrating at the time of the absorption event; this condition seems unlikely to be met at the low temperature of the interstellar medium, so the observed scarcity of narrow diffuse bands with this kind of asymmetry may have a simple explanation. The diffuseness of lambda6614 and most of the other narrow bands may owe more to the shading

  1. Charge radii of exotic nuclei: nuclear results versus isotopic shift calculations

    NASA Astrophysics Data System (ADS)

    Tomaselli, M.; Liu, L. C.; Fritzsche, S.; Kühl, T.; Ursescu, D.; Neumayer, P.; Wojtaszek, A.

    2004-12-01

    We study the charge radii of exotic nuclei through nuclear calculations and isotopic-shift evaluations. The computations are performed in the framework of the dynamic-correlation model DCM for nuclei with an odd number of valence particles and in the boson dynamic-correlation model (BCDM) for those with an even number of valence particles. These nuclear models take fully into consideration the correlation between valence particles as well as between valence and core particles. Consequently, these computations may reveal feature physics which is associated to the strong correlation between the valence and the core polarized states. Moreover,we propose to analyze the obtained charge radii within the isotopic shift theory in which the electronic transitions for lithium and lithium-like ions are calculated by considering the three correlated electrons described by a method similar to the nuclear DCM model.

  2. Isotope shifts in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations

    SciTech Connect

    Nazé, C.; Verdebout, S.; Godefroid, M.

    2014-09-15

    Energy levels, normal and specific mass shift parameters as well as electronic densities at the nucleus are reported for numerous states along the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with nuclear data, these electronic parameters can be used to determine values of level and transition isotope shifts. The calculation of the electronic parameters is done using first-order perturbation theory with relativistic configuration interaction wavefunctions that account for valence, core–valence, and core–core correlation effects as zero-order functions. Results are compared with experimental and other theoretical values, when available.

  3. Measurement of Plutonium Isotopic Composition - MGA

    SciTech Connect

    Vo, Duc Ta

    2015-08-21

    In this module, we will use the Canberra InSpector-2000 Multichannel Analyzer with a high-purity germanium detector (HPGe) and the MGA isotopic anlysis software to assay a variety of plutonium samples. The module provides an understanding of the MGA method, its attributes and limitations. You will assess the system performance by measuring a range of materials similar to those you may assay in your work. During the final verification exercise, the results from MGA will be combined with the 240Pueff results from neutron coincidence or multiplicity counters so that measurements of the plutonium mass can be compared with the operator-declared (certified) values.

  4. Deuterium isotope effects on ¹³C-NMR chemical shifts of 10-hydroxybenzo[h]quinolines.

    PubMed

    Hansen, Poul Erik; Kamounah, Fadhil S; Gryko, Daniel T

    2013-04-17

    Deuterium isotope effects on ¹³C-NMR chemical shifts are investigated in a series of 10-hydroxybenzo[h]quinolines (HBQ's) The OH proton is deuteriated. The isotope effects on ¹³C chemical shifts in these hydrogen bonded systems are rather unusual. The formal four-bond effects are found to be negative, indicating transmission via the hydrogen bond. In addition unusual long-range effects are seen. Structures, NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using DFT methods. Two-bond deuterium isotope effects on 13C chemical shifts are correlated with calculated OH stretching frequencies. Isotope effects on chemical shifts are calculated for systems with OH exchanged by OD. Hydrogen bond potentials are discussed. New and more soluble nitro derivatives are synthesized.

  5. Phase-shifting behaviour revisited: An alternative measure

    NASA Astrophysics Data System (ADS)

    Kang, Bo Soo; Ryu, Doojin; Ryu, Doowon

    2014-05-01

    This study re-examines the recently documented phase-shifting behaviour of financial markets using an alternative measure, an intraday return-based measure. While most previous studies on phase-shifting behaviour adopt the volume-imbalance measure proposed by Plerou et al. (2003), we find that our return-based measure successfully captures phase-shifting behaviour, and moreover exhibits a unique pattern of phase-shifting that is not detected when the classical volume imbalance measure is used. By analysing a high-frequency dataset of KOSPI200 futures, we also find that large trades reveal phase-shifting behaviour more clearly and significantly than smaller trades.

  6. Electric Dipole Moment Measurements with Rare Isotopes

    SciTech Connect

    Chupp, Timothy

    2016-11-11

    The origin of matter is one of the deepest questions addressed by science and remains a mystery because our understanding of the Big Bang suggests that equal amounts of matter as antimatter would be created and annihilate leaving nothing from which stars, galaxies, planets and ultimately life as we know it was created. We know this is not the case in the universe, and so the explanation that the laws of physics can distinguish the difference of moving forward and backward in time and provide mechanisms that produce more matter that antimatter so that a little bit was left over. These same laws of physics affect our world today and would very slightly change the shape of an atom, stretching is along the direction of the spin of its nucleus. This subtle shape change has been searched in many systems - the neutron, atoms and molecules, but has not yet been detected, even as the motivation is strengthened by our understanding of their structure. We therefore look to new systems that have special features that make these effects stand out. Rare isotopes provide one possibility and specific radon atoms are our choice. We have developed techniques to make these measurements with short-lived radioactive atoms, studied the nuclei to provide deeper understanding of how these affect arise in such atoms (including radium) and developed new laser-based techniques to measure and control the magnetic fields necessary to perform these exquisitely sensitive measurements. In this work we have shown that radioactive radon atoms can be produced and transported to an apparatus that lines up the spins of the atoms. We have also shown that the nuclei of nearby radium are pear shaped and that the radon nuclei likely oscillate from one pear shape to its mirror reflection. We have also used the techniques which control nuclear spin to study the magnetic environment in a magnetically shielded room, which has the smallest magnetic field in a large volume in the universe. Measuring magnetic

  7. Determination of nitrogen-15 isotope fractionation in tropine: evaluation of extraction protocols for isotope ratio measurement by isotope ratio mass spectrometry.

    PubMed

    Molinié, Roland; Kwiecień, Renata A; Silvestre, Virginie; Robins, Richard J

    2009-12-01

    N-Demethylation of tropine is an important step in the degradation of this compound and related metabolites. With the purpose of understanding the reaction mechanism(s) involved, it is desirable to measure the 15N kinetic isotope effects (KIEs), which can be accessed through the 15N isotope shift (Deltadelta15N) during the reaction. To measure the isotope fractionation in 15N during tropine degradation necessitates the extraction of the residual substrate from dilute aqueous solution without introducing artefactual isotope fractionation. Three protocols have been compared for the extraction and measurement of the 15N/14N ratio of tropine from aqueous medium, involving liquid-liquid phase partitioning or silica-C18 solid-phase extraction. Quantification was by gas chromatography (GC) on the recovered organic phase and delta15N values were obtained by isotope ratio measurement mass spectrometry (irm-MS). Although all the protocols used can provide satisfactory data and both irm-EA-MS and irm-GC-MS can be used to obtain the delta15N values, the most convenient method is liquid-liquid extraction from a reduced aqueous volume combined with irm-GC-MS. The protocols are applied to the measurement of 15N isotope shifts during growth of a Pseudomonas strain that uses tropane alkaloids as sole source of carbon and nitrogen. The accuracy of the determination of the 15N/14N ratio is sufficient to be used for the determination of 15N-KIEs. Copyright 2009 John Wiley & Sons, Ltd.

  8. Carbon isotope variation in mid-continent Ordovician-type oils: relationship to a major middle Ordovician carbon isotope shift

    SciTech Connect

    Hatch, J.R.; Jacobson, S.R.; Witzke, B.J.; Anders, D.E.; Watney, W.L.; Newell, K.D.

    1985-05-01

    Detailed organic geochemical comparisons of Mid-Continent Ordovician oils with extracts of potential source rocks show that in the Forest City basin of northeastern Kansas and southeastern Nebraska, oil source rocks are Middle Ordovician shales of the Simpson Group. For the Keota Dome field, Washington County, Iowa, the oil source rock is the Middle Ordovician Glenwood Shale Member of the Platteville Formation. Analyses of saturated and aromatic hydrocarbon fractions of Ordovician-type oils from the Forest City basin, Keota Dome field, and the Michigan basin show that sigma TC of the two fractions are similar and that sigma T varies over a considerable range, from -32.5 per mil to -25.5 per mil (PDB). This large range in sigma TC reflects a major shift in the carbon isotope composition of organic matter during the Middle Ordovician. This shift is shown in a 62.5-ft (19 m) interval of core from the Decorah and Platteville Formations in the E.M. Greene 1 well in Washington County, Iowa, where organic carbon sigma TC changes regularly upward from -32.2 per mil to -22.7 per mil (PDB). The change in organic carbon sigma TC in this core is not related to variations in amount (0.13-41.4% TOC) or type (hydrogen index = 69 to 1000 mg HC/g TOC) of the marginally mature (T/sub max/ = 440 +/- 5C) organic matter. Ordovician-type oils in both the Forest City and Michigan basins show variable sigma TC, suggesting that the sigma TC shift displayed in the Middle Ordovician rocks of southeastern Iowa is a regional and possibly a global effect, related to changes in the sigma TC of the ocean-atmosphere carbon reservoir. Isotopic analyses of coexisting carbonate minerals support this interpretation.

  9. ICP-MS for isotope ratio measurement

    USDA-ARS?s Scientific Manuscript database

    The use of stable isotopes in mineral nutrition research has become a fundamental aspect of conducting this research. A gradual transition has occurred, now virtually complete, from radioactive isotope studies to those using stable isotopes. Although primarily used in human research, mineral stable ...

  10. Penning trap mass measurements on nobelium isotopes

    SciTech Connect

    Dworschak, M.; Block, M.; Ackermann, D.; Herfurth, F.; Hessberger, F. P.; Hofmann, S.; Vorobyev, G. K.; Audi, G.; Blaum, K.; Droese, C.; Marx, G.; Schweikhard, L.; Eliseev, S.; Ketter, J.; Fleckenstein, T.; Haettner, E.; Plass, W. R.; Scheidenberger, C.; Ketelaer, J.; Kluge, H.-J.

    2010-06-15

    The Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt allows accurate mass measurements of radionuclides, produced in fusion-evaporation reactions and separated by the velocity filter SHIP from the primary beam. Recently, the masses of the three nobelium isotopes {sup 252-254}No were determined. These are the first direct mass measurements of transuranium elements, which provide new anchor points in this region. The heavy nuclides were produced in cold-fusion reactions by irradiating a PbS target with a {sup 48}Ca beam, resulting in production rates of the nuclei of interest of about one atom per second. In combination with data from decay spectroscopy our results are used to perform a new atomic-mass evaluation in this region.

  11. Penning trap mass measurements on nobelium isotopes

    NASA Astrophysics Data System (ADS)

    Dworschak, M.; Block, M.; Ackermann, D.; Audi, G.; Blaum, K.; Droese, C.; Eliseev, S.; Fleckenstein, T.; Haettner, E.; Herfurth, F.; Heßberger, F. P.; Hofmann, S.; Ketelaer, J.; Ketter, J.; Kluge, H.-J.; Marx, G.; Mazzocco, M.; Novikov, Yu. N.; Plaß, W. R.; Popeko, A.; Rahaman, S.; Rodríguez, D.; Scheidenberger, C.; Schweikhard, L.; Thirolf, P. G.; Vorobyev, G. K.; Wang, M.; Weber, C.

    2010-06-01

    The Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt allows accurate mass measurements of radionuclides, produced in fusion-evaporation reactions and separated by the velocity filter SHIP from the primary beam. Recently, the masses of the three nobelium isotopes No252-254 were determined. These are the first direct mass measurements of transuranium elements, which provide new anchor points in this region. The heavy nuclides were produced in cold-fusion reactions by irradiating a PbS target with a Ca48 beam, resulting in production rates of the nuclei of interest of about one atom per second. In combination with data from decay spectroscopy our results are used to perform a new atomic-mass evaluation in this region.

  12. Laser spectroscopic measurement of helium isotope ratios.

    SciTech Connect

    Wang, L.-B.; Mueller, P.; Holt, R. J.; Lu, Z.-T.; O'Connor, T. P.; Sano, Y.; Sturchio, N.; Univ. of Illinois; Univ. of Tokyo; Univ. of Illinois at Chicago

    2003-06-13

    A sensitive laser spectroscopic method has been applied to the quantitative determination of the isotope ratio of helium at the level of {sup 3}He/{sup 4}He = 10{sup -7}--10{sup -5}. The resonant absorption of 1083 nm laser light by the metastable {sup 3}He atoms in a discharge cell was measured with the frequency modulation saturation spectroscopy technique while the abundance of {sup 4}He was measured by a direct absorption technique. The results on three different samples extracted from the atmosphere and commercial helium gas were in good agreement with values obtained with mass spectrometry. The achieved 3{sigma} detection limit of {sup 3}He in helium is 4 x 10{sup -9}. This demonstration required a 200 {mu}L STP sample of He. The sensitivity can be further improved, and the required sample size reduced, by several orders of magnitude with the addition of cavity enhanced spectroscopy.

  13. Geometries and tautomerism of OHN hydrogen bonds in aprotic solution probed by H/D isotope effects on (13)C NMR chemical shifts.

    PubMed

    Tolstoy, Peter M; Guo, Jing; Koeppe, Benjamin; Golubev, Nikolai S; Denisov, Gleb S; Smirnov, Sergei N; Limbach, Hans-Heinrich

    2010-10-14

    The (1)H and (13)C NMR spectra of 17 OHN hydrogen-bonded complexes formed by CH(3)(13)COOH(D) with 14 substituted pyridines, 2 amines, and N-methylimidazole have been measured in the temperature region between 110 and 150 K using CDF(3)/CDF(2)Cl mixture as solvent. The slow proton and hydrogen bond exchange regime was reached, and the H/D isotope effects on the (13)C chemical shifts of the carboxyl group were measured. In combination with the analysis of the corresponding (1)H chemical shifts, it was possible to distinguish between OHN hydrogen bonds exhibiting a single proton position and those exhibiting a fast proton tautomerism between molecular and zwitterionic forms. Using H-bond correlations, we relate the H/D isotope effects on the (13)C chemical shifts of the carboxyl group with the OHN hydrogen bond geometries.

  14. Synthetic isotope mixtures for the calibration of isotope amount ratio measurements of carbon

    NASA Astrophysics Data System (ADS)

    Russe, K.; Valkiers, S.; Taylor, P. D. P.

    2004-07-01

    Synthetic isotope mixtures for the calibration of carbon isotope amount ratio measurements have been prepared by mixing carbon tetrafluoride highly enriched in 13C with carbon tetrafluoride depleted in 13C. Mixing procedures based on volumetry and gravimetry are described. The mixtures served as primary measurement standards for the calibration of isotope amount ratio measurements of the Isotopic Reference Materials PEF1, NBS22 and USGS24. Thus SI-traceable measurements of absolute carbon isotope amount ratios have been performed for the first time without any hypothesis needed for a correction of oxygen isotope abundances, such as is the case for measurements on carbon dioxide. As a result, "absolute" carbon isotope amount ratios determined via carbon tetrafluoride have smaller uncertainties than those published for carbon dioxide. From the measurements of the Reference Materials concerned, the absolute carbon isotope amount ratio of Vienna Pee Dee Belemnite (VPDB)--the hypothetical material upon which the scale for relative carbon isotope ratio measurements is based--was calculated to be R13(VPDB) = (11 101 +/- 16) × 10-6.

  15. Isotope shift calculations for D lines of stable and short-lived lithium nuclei

    NASA Astrophysics Data System (ADS)

    Yu, Geng-Hua; Zhao, Peng-Yi; Xu, Bing-Ming; Yang, Wei; Zhu, Xiao-Ling

    2016-11-01

    The isotope shifts (ISs) for the 2s2S1/2 to 2p2P J (J = 1/2, 3/2) transitions of the lithium nuclei including the stable and short-lived isotopes are calculated based on the multi-configuration Dirac-Hartree-Fock method and the relativistic configuration interaction approach. The results are in good agreement with the previous theoretical and experimental results within a deviation less than 0.05%. The methods used here could be applied to the IS calculations for other heavier Li-like ions and few-electron systems. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 11304093), the Fund of the Scientific Research Foundation of Sichuan Provincial Department of Education, China (Grant No. 15ZB0386), and the Fund of the 1315 Project of Chengdu University, China (Grant No. 2081915041).

  16. Isotope shifts and transition frequencies for the S and P states of lithium: Bethe logarithms and second-order relativistic recoil

    NASA Astrophysics Data System (ADS)

    Wang, L. M.; Li, Chun; Yan, Z.-C.; Drake, G. W. F.

    2017-03-01

    Isotope shifts and total transition frequencies are calculated for the 2 2S-3 2S transition of the lithium isotopes 6Li, 7Li, 8Li, 9Li, and the halo nucleus 11Li. The accuracy is improved for previously calculated relativistic and quantum electrodynamic corrections, and in particular a disagreement for the Bethe logarithm is resolved for the ground 2S state. Our previous result is confirmed for the 2 2P state. We use the pseudostate expansion method to perform the sum over virtual intermediate states. Results for the second-order relativistic recoil term of order α2(μ/M ) 2 Ry are shown to make a significant contribution relative to the theoretical uncertainty, but because of accidental cancellations the final result for the isotope shift is nearly unchanged. However, the spin-orbit term makes an unexpectedly large contribution to the splitting isotope shift (SIS) for the 2 1/2 2P -2 3/2 2P fine structure, increasing the theoretical value for the 6Li-7Li isotopes to 0.556 31 (7 )±0.001 MHz. A comparison is made with high-precision measurements and other calculations for the SIS and for the total 2 2S-3 2S transition frequency.

  17. Measurement of isotope abundance variations in nature by gravimetric spiking isotope dilution analysis (GS-IDA).

    PubMed

    Chew, Gina; Walczyk, Thomas

    2013-04-02

    Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

  18. Ozone isotope measurements in the stratosphere

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.

    1987-01-01

    Mass spectrometer measurements of ozone made during two balloon flights included its heavy isotopes at mass 49 and 50. Both flights were flown during the day and during summer from Palestine, TX. At float altitudes above 42 km the enrichments in heavy ozone were 41 percent and 23 percent, respectively. The enrichment appears to be mass independent since, at high altitudes, both 49 and 50 show the same enhancement. During the descent the enrichment in heavy ozone decreased, faster during the first flight than during the second, reaching values between 15 and 20 percent above 30 km. Near and below this altitude another increase is observed. During a night flight, previously reported, an enhancement in heavy ozone of over 40 percent at 32 km was found, decreasing both toward higher and lower altitudes.

  19. Isotope Shift in the Dielectronic Recombination of Three-Electron {sup A}Nd{sup 57+}

    SciTech Connect

    Brandau, C.; Kozhuharov, C.; Bosch, F.; Kluge, H.-J.; Stoehlker, Th.; Beckert, K.; Beller, P.; Nolden, F.; Steck, M.; Gumberidze, A.; Reuschl, R.; Spillmann, U.; Harman, Z.; Jentschura, U. D.; Keitel, C. H.; Wolf, A.; Mueller, A.; Schippers, S.; Bernhardt, D.; Boehm, S.

    2008-02-22

    Isotope shifts in dielectronic recombination spectra were studied for Li-like {sup A}Nd{sup 57+} ions with A=142 and A=150. From the displacement of resonance positions energy shifts {delta}E{sup 142} {sup 150}(2s-2p{sub 1/2})=40.2(3)(6) meV [(stat)(sys)] and {delta}E{sup 142} {sup 150}(2s-2p{sub 3/2})=42.3(12)(20) meV of 2s-2p{sub j} transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of {sup 142} {sup 150}{delta}=-1.36(1)(3) fm{sup 2}. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size.

  20. Measuring In Vivo Ureagenesis With Stable Isotopes

    PubMed Central

    Yudkoff, Marc; Mew, Nicholas Ah; Daikhin, Yevgeny; Horyn, Oksana; Nissim, Ilana; Nissim, Itzhak; Payan, Irma; Tuchman, Mendel

    2010-01-01

    Stable isotopes have been an invaluable adjunct to biomedical research for more than 70 years. Indeed, the isotopic approach has revolutionized our understanding of metabolism, revealing it to be an intensely dynamic process characterized by an unending cycle of synthesis and degradation. Isotopic studies have taught us that the urea cycle is intrinsic to such dynamism, since it affords a capacious mechanism by which to eliminate waste nitrogen when rates of protein degradation (or dietary protein intake) are especially high. Isotopes have enabled an appreciation of the degree to which ureagenesis is compromised in patients with urea cycle defects. Indeed, isotopic studies of urea cycle flux correlate well with the severity of cognitive impairment in these patients. Finally, the use of isotopes affords an ideal tool with which to gauge the efficacy of therapeutic interventions to augment residual flux through the cycle. PMID:20338795

  1. Short course on St-02 applications of isotope dilutions and isotopic measurements

    SciTech Connect

    Miller, P.

    1998-01-05

    This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological.

  2. Nitrogen isotope fractionation during archaeal ammonia oxidation: Coupled estimates from isotopic measurements of ammonium and nitrite

    NASA Astrophysics Data System (ADS)

    Mooshammer, Maria; Stieglmeier, Michaela; Bayer, Barbara; Jochum, Lara; Melcher, Michael; Wanek, Wolfgang

    2014-05-01

    Ammonia-oxidizing archaea (AOA) are ubiquitous in marine and terrestrial environments and knowledge about the nitrogen (N) isotope effect associated with their ammonia oxidation activity will allow a better understanding of natural abundance isotope ratios, and therefore N transformation processes, in the environment. Here we examine the kinetic isotope effect for ammonia oxidation in a pure soil AOA culture (Ca. Nitrososphaera viennensis) and a marine AOA enrichment culture. We estimated the isotope effect from both isotopic signatures of ammonium and nitrite over the course of ammonia oxidation. Estimates of the isotope effect based on the change in the isotopic signature of ammonium give valuable insight, because these estimates are not subject to the same concerns (e.g., accumulation of an intermediate) as estimates based on isotopic measurements of nitrite. Our results show that both the pure soil AOA culture and a marine AOA enrichment culture have similar but substantial isotope effect during ammonia consumption (31-34 per mill; based on ammonium) and nitrite production (43-45 per mill; based on nitrite). The 15N fractionation factors of both cultures tested fell in the upper range of the reported isotope effects for archaeal and bacterial ammonia oxidation (10-41 per mill) or were even higher than those. The isotope fractionation for nitrite production was significantly larger than for ammonium consumption, indicating that (1) some intermediate (e.g., hydroxylamine) of ammonia oxidation accumulates, allowing for a second 15N fractionation step to be expressed, (2) a fraction of ammonia oxidized is lost via gaseous N forms (e.g., NO or N2O), which is 15N-enriched or (3) a fraction of ammonium is assimilated into AOA biomass, biomass becoming 15N-enriched. The significance of these mechanisms will be explored in more detail for the soil AOA culture, based on isotope modeling and isotopic measurements of biomass and N2O.

  3. Picosecond time-resolved measurements of dense plasma line shifts

    DOE PAGES

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; ...

    2017-06-13

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1s2p–1s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al Heα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing red shift for electron densities of 1 to 5 × 1023 cm–3. Furthermore, the measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion sphere model.

  4. Weak measurement of the Goos-Hänchen shift.

    PubMed

    Jayaswal, G; Mistura, G; Merano, M

    2013-04-15

    It is well known from quantum mechanics that weak measurements offer a means of amplifying and detecting very small phenomena. We present here the experimental observation of the Goos-Hänchen shift via a weak measurement approach.

  5. Integrated phase shift measurements for advanced mask etch process control

    NASA Astrophysics Data System (ADS)

    Sahin, Turgut; Collard, Corey; Anderson, Scott A.; Mak, Alfred W.; Brooks, Cynthia B.; Buie, Melisa J.; Walsh, Philip; Li, George

    2003-12-01

    The phase shift effect in Alternating Phase Shift Masks (AAPSMs) and chrome-less phase shift masks is created by etching trenches directly into the quartz substrate. Since the phase shift is critically dependent on the etch depth, the quartz etch process must be tightly controlled. In the absence of an etch stop for the process, an integrated metrology solution is desirable on the mask tech tool. Traditional methods for measuring etch depth or phase shift, such as interferometry, profilometry, AFM, and SEM, are expensive, slow, and/or destructive. In addition, traditional methods cannot measure quartz etch depth without removing the resist and in some cases the chrome mask, making them unsuitable for integration into the etch process. This paper will present measurements of trench depth and phase shift on quartz phase shift mask using the n&k Analyzer 1512-RT. The n&k Analyzer measures reflectance (R) and transmittance (T) from 190-1000nm, which is analyzed according to the Forouhi-Bloomer dispersion relations to simultaneously determine n, k, film thicknesses, trench depth, and phase shift. The measurement is non-destructive and fast, typically taking 2-3 seconds per measurement point. No special test structures are required for the measurement. In addition, the n&k Analyzer can measure quartz etch depth with the chrome mask, ARC layers, and resist still intact. The n&k Analyzer measurements show good correlation with 193nm interferometer measurements, and good repeatability. The small footprint, ease of use, measurement speed, and the ability to measure quartz depth in the presence of chrome and resist make the n&k Analyzer an ideal candidate for integrated metrology applications on mask etch tools for advanced proces control (APC). The Applied Materials' Tetra II phootmask etch system has the unique capability to accommodate integrated metrology modules through the factory interface. Applications of APC with integrated phase shift measurements will be discussed.

  6. Evaluating climate controls on isotopic shifts in high-altitude forests during the Last Interglacial

    NASA Astrophysics Data System (ADS)

    Insel, N.; Berkelhammer, M. B.; Sturm, C.; Karimova, G.

    2016-12-01

    Forests play a significant role in the global carbon cycle, and influence climate through their effect on albedo and latent heat flux. Predicting the response of these ecosystems to climate change is complicated by competing influences between rising CO2, warming, and shifts in hydrology such as timing, rate, and type of precipitation. A key to detection and prediction of future regional and global changes of modern ecosystems lies in understanding the causes and characteristics of historical variations at the ecosystem level. The Last Interglacial (LIG: 130 to 116 ka) is the most recent period in Earth's history when growing season temperature exceeded those of today. In this study, we are using isotope-enabled regional climate model (REMOiso) simulations under LIG (115ka, 125 ka and 135 ka) and modern forcings to evaluate climate controls on boreal forest in the western US. In particular, we investigate (1) changes in moisture sources and moisture transport, (2) changes in the annual and seasonal extent and duration of precipitation, and (3) temperature variations to explore how ecosystem carbon and water fluxes change under coupled temperature and precipitation variability. Eemian wood samples from the Rocky Mountains in Colorado show a progressive increase in the 18O seasonal cycle that may be related to trees utilizing isotopically enriched monsoonal moisture. However, Eemian climate simulations (125ka) incorporate orbital forcings that result in stronger seasonal changes in temperature, precipitation, and snow cover in comparison to today, while annual anomalies are small. The seasonal shift in climate affects the water availability and the length of growing season for Eemian plants. Model results indicate only a very slight increase in monsoonal moisture transport from the south, resulting in slightly wetter conditions in western Colorado, but slightly drier conditions in the eastern part. Preliminary results suggest that changes in the North American

  7. Stable isotopes in fossil hominin tooth enamel suggest a fundamental dietary shift in the Pliocene.

    PubMed

    Lee-Thorp, Julia A; Sponheimer, Matt; Passey, Benjamin H; de Ruiter, Darryl J; Cerling, Thure E

    2010-10-27

    Accumulating isotopic evidence from fossil hominin tooth enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C(4) photosynthesis, consisting of C(4) tropical/savannah grasses and certain sedges, and/or animals eating C(4) foods. Moreover, high-resolution analysis of tooth enamel reveals strong intra-tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even 'savannah' chimpanzees. The overall proportions of C(4) input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C(4) plants, in spite of indications from their powerful 'nutcracker' morphology for diets of hard objects. We argue that such evidence for engagement with C(4) food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.

  8. Stable isotopes in fossil hominin tooth enamel suggest a fundamental dietary shift in the Pliocene

    PubMed Central

    Lee-Thorp, Julia A.; Sponheimer, Matt; Passey, Benjamin H.; de Ruiter, Darryl J.; Cerling, Thure E.

    2010-01-01

    Accumulating isotopic evidence from fossil hominin tooth enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C4 photosynthesis, consisting of C4 tropical/savannah grasses and certain sedges, and/or animals eating C4 foods. Moreover, high-resolution analysis of tooth enamel reveals strong intra-tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even ‘savannah’ chimpanzees. The overall proportions of C4 input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C4 plants, in spite of indications from their powerful ‘nutcracker’ morphology for diets of hard objects. We argue that such evidence for engagement with C4 food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago. PMID:20855312

  9. Stable isotopes reveal habitat-related diet shifts in facultative deposit-feeders

    NASA Astrophysics Data System (ADS)

    Rossi, Francesca; Baeta, Alexandra; Marques, João C.

    2015-01-01

    Seagrass patches interspersed in a sediment matrix may vary environmental conditions and affect feeding habits of consumers and food-web structure. This paper investigates diet shifts between bare sediments and a Zostera noltei (Hornemann, 1832) meadow for three facultative deposit-feeding macrofaunal consumers, notably the bivalve Scrobicularia plana (da Costa, 1778), the polychaete Hediste diversicolor (O.T. Müller, 1776), and the gastropod Hydrobia ulvae (Pennant, 1778). In July 2008, one eelgrass meadow and two bare sediment locations were chosen in the Mondego estuary (40° 08″ N, 8° 50‧ W, Portugal) and sampled for stable isotope signatures (δ13C and δ15N) of macrofauna consumers and some of their potential basal food sources, such as sedimentary organic matter (SOM), microphytobenthos (MPB), seagrass shoots, leaves and seaweeds laying on the surface sediment. The δ15N of H. diversicolor was 3‰ higher in the eelgrass meadow than in bare sediment, indicating a change of trophic position, whereas the Bayesian stable-isotope mixing model showed that S. plana assimilated more macroalgal detritus than microphytobenthos in the eelgrass bed. Such habitat-related diet shifts have the potential to change structure and spatial dynamics of benthic food webs.

  10. Measuring the entropy from shifted boundary conditions

    NASA Astrophysics Data System (ADS)

    Giusti, L.; Pepe, M.

    We explore a new computational strategy for determining the equation of state of the SU(3) Yang-Mills theory. By imposing shifted boundary conditions, the entropy density is computed from the vacuum expectation value of the off-diagonal components T_{0k} of the energy-momentum tensor. A step-scaling function is introduced to span a wide range in temperature values. We present preliminary numerical results for the entropy density and its step-scaling function obtained at eight temperature values in the range T_c - 15 T_c. At each temperature, discretization effects are removed by simulating the theory at several lattice spacings and by extrapolating the results to the continuum limit. Finite-size effects are always kept below the statistical errors. The absence of ultraviolet power divergences and the remarkably small discretization effects allow for a precise determination of the step-scaling function in the explored temperature range. These findings establish this strategy as a viable solution for an accurate determination of the equation of state in a wide range of temperature values.

  11. A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Lopez-Veneroni, D. G.; Vega, E.

    2013-05-01

    The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

  12. Quantitative analysis of deuterium using the isotopic effect on quaternary (13)C NMR chemical shifts.

    PubMed

    Darwish, Tamim A; Yepuri, Nageshwar Rao; Holden, Peter J; James, Michael

    2016-07-13

    Quantitative analysis of specifically deuterated compounds can be achieved by a number of conventional methods, such as mass spectroscopy, or by quantifying the residual (1)H NMR signals compared to signals from internal standards. However, site specific quantification using these methods becomes challenging when dealing with non-specifically or randomly deuterated compounds that are produced by metal catalyzed hydrothermal reactions in D2O, one of the most convenient deuteration methods. In this study, deuterium-induced NMR isotope shifts of quaternary (13)C resonances neighboring deuterated sites have been utilized to quantify the degree of isotope labeling of molecular sites in non-specifically deuterated molecules. By probing (13)C NMR signals while decoupling both proton and deuterium nuclei, it is possible to resolve (13)C resonances of the different isotopologues based on the isotopic shifts and the degree of deuteration of the carbon atoms. We demonstrate that in different isotopologues, the same quaternary carbon, neighboring partially deuterated carbon atoms, are affected to an equal extent by relaxation. Decoupling both nuclei ((1)H, (2)H) resolves closely separated quaternary (13)C signals of the different isotopologues, and allows their accurate integration and quantification under short relaxation delays (D1 = 1 s) and hence fast accumulative spectral acquisition. We have performed a number of approaches to quantify the deuterium content at different specific sites to demonstrate a convenient and generic analysis method for use in randomly deuterated molecules, or in cases of specifically deuterated molecules where back-exchange processes may take place during work up.

  13. Measurement of the isotope shift of the 2{{\\rm{p}}}^{4}{}^{3}{{P}}_{2} \\rightarrow 2{{\\rm{p}}}^{3}3{\\rm{p}}{}^{3}{{P}}_{2} two-photon transition of O I and a revision of the triplet energy levels of atomic oxygen

    NASA Astrophysics Data System (ADS)

    Marinov, D.; Booth, J.-P.; Drag, C.; Blondel, C.

    2017-03-01

    Two-photon induced fluorescence of atomic oxygen, which is routinely used for plasma and flame diagnostics, is implemented with two counterpropagating laser beams of sufficient monochromaticity to permit Doppler-free spectroscopy. A single-mode injection-seeded pulsed Ti:sapphire laser has been frequency-doubled twice to produce narrow-band pulsed radiation at wavelengths around 225.6 nm, suitable to excite the ground-state-to-2{{{p}}}33{{p}}{}3{P} two-photon resonance line of oxygen. Accurate measurement of the injection-seeding wavelength provides new data on the excitation energy of the 3{{p}}{}3{P} states. The experiment was done both sequentially and simultaneously on 16O and 18O, which makes it possible to test recent calculations of the isotope shift. Having an absolute measurement of the excitation wave-number from the ground level, which has been the case only twice in previous spectroscopic studies of O I, we can re-examine the energy levels of the subset of triplet states and present an updated set of optimised energy values.

  14. Stable isotope analysis of CO2 in breath indicates metabolic fuel shifts in torpid arctic ground squirrels.

    PubMed

    Lee, Trixie N; Richter, Melanie M; Williams, Cory T; Tøien, Øivind; Barnes, Brian M; O'Brien, Diane M; Buck, C Loren

    2017-07-01

    Stable carbon isotope ratios (δ(13)C) in breath show promise as an indicator of immediate metabolic fuel utilization in animals because tissue lipids have a lower δ(13)C value than carbohydrates and proteins. Metabolic fuel consumption is often estimated using the respiratory exchange ratio (RER), which has lipid and carbohydrate boundaries, but does not differentiate between protein and mixed fuel catabolism at intermediate values. Because lipids have relatively low δ(13)C values, measurements of stable carbon isotopes in breath may help distinguish between catabolism of protein and mixed fuel that includes lipid. We measured breath δ(13)C and RER concurrently in arctic ground squirrels (Urocitellus parryii) during steady-state torpor at ambient temperatures from -2 to -26°C. As predicted, we found a correlation between RER and breath δ(13)C values; however, the range of RER in this study did not reach intermediate levels to allow further resolution of metabolic substrate use with the addition of breath δ(13)C measurements. These data suggest that breath δ(13)C values are 1.1‰ lower than lipid tissue during pure lipid metabolism. From RER, we determined that arctic ground squirrels rely on nonlipid fuel sources for a significant portion of energy during torpor (up to 37%). The shift toward nonlipid fuel sources may be influenced by adiposity of the animals in addition to thermal challenge. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Doppler-Shifted Raman Spectroscopy Measures Flows

    NASA Technical Reports Server (NTRS)

    Exton, Reginald J.; Hillard, Mervin E., Jr.; Lempert, Walter R.; Covell, Peter F.; Miller, David S.

    1990-01-01

    Technique for measuring velocity, static pressure, and translational temperature of flowing molecules by use of stimulated Raman spectroscopy demonstrated in supersonic wind tunnel at NASA Langley Research Center. Nonintrusive, accurate wind-tunnel measurements obtained without seeding flows. Optical equipment for vibration-free Raman doppler velocimetry in wind tunnel includes specially designed retrometer that reduces sensitivity of system to vibrations. This capability very valuable in aerodynamic testing and proves useful in wide variety of laboratory, industrial, and engineering applications.

  16. Quantitative measurement of the pivot shift, reliability, and clinical applications.

    PubMed

    Kuroda, Ryosuke; Hoshino, Yuichi; Araki, Daisuke; Nishizawa, Yuichiro; Nagamune, Kouki; Matsumoto, Tomoyuki; Kubo, Seiji; Matsushita, Takehiko; Kurosaka, Masahiro

    2012-04-01

    Static load-displacement measurement is unrelated to the dynamic knee function of anterior cruciate ligament (ACL) insufficiency. Performing an accurate, dynamic functional evaluation is necessary not only for the primary ACL injury, but also as an outcome measurement in ACL reconstruction. The pivot shift test is commonly used for assessing dynamic rotatory knee laxity in ACL-insufficient knees and is related to subjective knee function. Residual pivot shift after ACL reconstruction is a crucial factor related to poor clinical outcome. However, the pivot shift test is subjectively determined by the examiners' hands. Not only 3-dimensional (3D) position displacement but also its 3D acceleration should be measured for quantitative evaluation of the pivot shift test and is currently feasible by using recent advanced technology, i.e., electromagnetic devices. We summarize the basic knowledge and current concepts of quantitative exploration of the dynamic knee movement during the pivot shift test.

  17. Isotopic CO2 Instrumentation for UAV Measurements

    NASA Astrophysics Data System (ADS)

    Gomez, A.; Silver, J.

    2013-12-01

    Carbon dioxide is the largest component of anthroprogenic green house gas emissions. Knowing atmospheric 13CO2/12CO2 ratios precisely is important for understanding biogenic and anthroprogenic sources and sinks for carbon. Instrumentation mounted on UAV aircraft would enable important spatial isotopic CO2 information. However, current isotopic CO2 instrumentation have unfavorable attributes for UAV use, such as high power requirements, high cost, high weight, and large size. Here we present the early development of a compact isotopic CO2 instrument that is designed to nullify effects of pressure, temperature and moisture, and will ultimately be suitable for UAV deployment.

  18. Isotopic shifts in chemical exchange systems. 1. Large isotope effects in the complexation of Na/sup +/ isotopes by macrocyclic polyethers

    SciTech Connect

    Knoechel, A.; Wilken, R.D.

    1981-09-23

    The complexation of /sup 24/Na/sup +/ and /sup 22/Na/sup +/ by 18 of the most widely used macrocyclic polyethers (crown ethers and monocyclic and bicyclic aminopolyethers) has been investigated in view of possible equilibrium isotope shifts. Solvated salts and polyether complexes were distributed differently into two phases and isotope ratios determined in both phases. Chloroform/water systems were shown to be particularly suitable to the investigations allowing favorable distribution for Na/sup +/ and 13 of the 18 polyethers employed. With crown ethers /sup 24/Na/sup +/ enrichment varied from nonsignficant values (for large crown ethers) up to 3.1 +- 0.4% (18-crown-6). In the case of bicyclic aminopolyethers, ligands with cages of optimum size to accommodate Na/sup +/ showed /sup 24/Na/sup +/ enrichment between O (nonsignificant) (2.2/sub B/2./sub B/) and 5.2 +- 1.8% (2.2.1). In contrast, for 2.2.2. and its derivatives, being too large for Na/sup +/, /sup 22/Na/sup +/ enrichment varying from O (nonsignificant) (2.2.2.p) up to 5.4 +- 0.5% (2.2.2.) has been observed. These values are remarkably high. They are explained by different bonding in solvate structure and polyether complex by using the theoretical approach of Bigeleisen.

  19. Using C stable isotopes to infer shifting metabolism in response to variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Ballantyne, Ford; Billings, Sharon; Lehmeier, Christoph; Min, Kyungjin

    2014-05-01

    The flow of carbon (C) from organic matter substrates through microbial biomass and into CO2 comprises a complex suite of processes. Organic matter compounds are modified by extracellular enzyme activity, potentially taken up by microbes, and can either remain as altered organic compounds in the soil matrix, or are transformed into inorganic C forms, including CO2. During these transformations, discrimination between 12C and 13C occurs. The net result of all fractionations is what we observe in the δ13C of respired CO2. However, our understanding of fractionations associated with soil organic matter (SOM) transformations is far from complete, especially for biologically-mediated transformations. To make proper inference from δ13C values of respired CO2, we need a more comprehensive understanding of what governs isotopic fractionation along the path from SOM to CO2 release. Here, we present equations for 12C and 13C dynamics in a chemostat system, with which C flux data coupled to isotopic ratios can be used to infer the degree of fractionation associated with functionally distinct processes. Using patterns in the fractionation between substrate and biomass and between biomass and respired CO2 observed for Pseudomonas fluorescens in the experimental chemostat system, we argue that a single mechanism cannot be responsible for temperature-induced changes in the flow rates of 12C and 13C from a single substrate, cellobiose, into respired CO2. We further describe how changing C availability can influence fractionation among C pools and compare predictions to chemostat runs for which C availability varied. Our modeling applied to observed C isotope fluxes strongly suggests that significant discrimination against 13C occurs during cellobiose uptake by P. fluorescens, and that apparently smooth changes in specific respiration rates and associated C use efficiency are actually the result of discontinuous shifts in C flow through anabolic and catabolic pathways. Accounting

  20. Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

    NASA Astrophysics Data System (ADS)

    Xie, Xueshu; Zubarev, Roman A.

    2015-03-01

    Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some ``resonance'' isotopic compositions, the kinetics increases, while at ``off-resonance'' compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error +/-0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p << 10-15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas.

  1. Accurate Xe isotope measurement using JPL ion trap.

    PubMed

    Madzunkov, Stojan M; Nikolić, Dragan

    2014-11-01

    We report an approach for the reproducible and accurate compositional analysis of different mixtures of Xe isotopes using miniature Jet Propulsion Laboratory Quadrupole Ion Trap (JPL-QIT). A major study objective was to validate the recent instrumental improvements to the long-term operational stability under different pressures, temperatures, and trapping conditions. We propose that the present device can be used in certification of trace amounts of isotopes in mixtures dominated by one or more isotopes. Measured isotopic compositions are verified against commercially available standards with accuracy better than 0.07%. To aid the analysis of experimental data, we developed a scalable replica fitting method and use peak areas as descriptors of relative isotopic abundances. This low-power and low-mass device is ideally suited for planetary explorations aimed to enhance quantitative analysis for major isotopes present in small amounts of atmospheric samples.

  2. Towards absolute laser spectroscopic CO2 isotope ratio measurements

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Werhahn, Olav; Ebert, Volker

    2017-04-01

    Knowledge of isotope composition of carbon dioxide (CO2) in the atmosphere is necessary to identify sources and sinks of this key greenhouse gas. In the last years, laser spectroscopic techniques such as cavity ring-down spectroscopy (CRDS) and tunable diode laser absorption spectroscopy (TDLAS) have been shown to perform accurate isotope ratio measurements for CO2 and other gases like water vapour (H2O) [1,2]. Typically, isotope ratios are reported in literature referring to reference materials provided by e.g. the International Atomic Energy Agency (IAEA). However, there could be some benefit if field deployable absolute isotope ratio measurement methods were developed to address issues such as exhausted reference material like the Pee Dee Belemnite (PDB) standard. Absolute isotope ratio measurements would be particularly important for situations where reference materials do not even exist. Here, we present CRDS and TDLAS-based absolute isotope ratios (13C/12C ) in atmospheric CO2. We demonstrate the capabilities of the used methods by measuring CO2 isotope ratios in gas standards. We compare our results to values reported for the isotope certified gas standards. Guide to the expression of uncertainty in measurement (GUM) compliant uncertainty budgets on the CRDS and TDLAS absolute isotope ratio measurements are presented, and traceability is addressed. We outline the current impediments in realizing high accuracy absolute isotope ratio measurements using laser spectroscopic methods, propose solutions and the way forward. Acknowledgement Parts of this work have been carried out within the European Metrology Research Programme (EMRP) ENV52 project-HIGHGAS. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. References [1] B. Kühnreich, S. Wagner, J. C. Habig,·O. Möhler, H. Saathoff, V. Ebert, Appl. Phys. B 119:177-187 (2015). [2] E. Kerstel, L. Gianfrani, Appl. Phys. B 92, 439-449 (2008).

  3. Neutron Capture Measurements on Tl-isotopes at DANCE

    NASA Astrophysics Data System (ADS)

    Couture, A.; Bredeweg, T. A.; Esch, E.-I.; Jandel, M.; Haight, R. C.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.

    2006-10-01

    The thallium isotopes play an important role in the s-process nucleosynthesis at the s-process endpoint. Furthermore, ^204Tl is one of few branch point isotopes in the endpoint region. The understanding of branch point isotopes provides modeling constraints on the temperatures during which the process takes place. The production of s-only ^204Pb is controlled entirely by ^204Tl. Measurements of the capture cross-sections of the stable Tl isotopes have recently been made using the DANCE 4-π array at LANSCE. This provides needed resonance information in the region as well as preparing the way for measurements of as yet unmeasured capture cross-section of the unstable ^204Tl. The neutron capture data for the stable isotopes as well as the plan for future measurements will be discussed.

  4. Isotope shifts of the 2 p3 /2-2 p1 /2 transition in B-like ions

    NASA Astrophysics Data System (ADS)

    Zubova, N. A.; Malyshev, A. V.; Tupitsyn, I. I.; Shabaev, V. M.; Kozhedub, Y. S.; Plunien, G.; Brandau, C.; Stöhlker, Th.

    2016-05-01

    Isotope shifts of the 2 p3 /2-2 p1 /2 transition in B-like ions are evaluated for a wide range of the nuclear charge number: Z =8 -92 . The calculations of the relativistic nuclear recoil and nuclear size effects are performed using a large-scale configuration-interaction Dirac-Fock-Sturm method. The corresponding QED corrections are also taken into account. The results of the calculations are compared with the theoretical values obtained with other methods. The accuracy of the isotope shifts of the 2 p3 /2-2 p1 /2 transition in B-like ions is significantly improved.

  5. Picosecond time-resolved measurements of dense plasma line shifts

    NASA Astrophysics Data System (ADS)

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; Golovkin, I. E.; Mileham, C.; Begishev, I. A.; Froula, D. H.

    2017-06-01

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1 s 2 p -1 s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al H eα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing redshift for electron densities of 1 -5 ×1023c m-3 . The measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion-sphere model.

  6. Spectroscopic determination of the ground-state dissociation energy and isotopic shift of NaD

    NASA Astrophysics Data System (ADS)

    Chu, Chia-Ching; He, Wei-Fung; Lin, Rong-Sin; Li, Yin-Ji; Whang, Thou-Jen; Tsai, Chin-Chun

    2017-07-01

    Stimulated emission pumping with fluorescence depletion spectroscopy is used to determine the NaD X 1Σ+ ground-state dissociation energy and its isotopic shift. A total of 230 rovibrational levels in the range 9 ≤ v″ ≤ 29 and 1 ≤ J″ ≤ 11 are observed, where v″ = 29 is about 50 cm-1 below the dissociation limit. Analysis of the highest five vibrational levels yields the dissociation energy De = 15 822 ± 5 cm-1 with a vibrational quantum number at dissociation vD = 31.2 ± 0.1. The energy difference in the well depth of this isotopologue with respect to that of NaH is δDe = De(NaH) - De(NaD) = -7 cm-1. A new set of Dunham coefficients is derived to fit all the observed energy levels to within the experimental uncertainty.

  7. Oxygen Isotopes in Fresh Water Biogenic Opal: Northeastern US Alleroed-Younger Dryas Temperature Shift

    NASA Technical Reports Server (NTRS)

    Shemesh, Aldo; Peteet, Dorothy

    1997-01-01

    The first oxygen isotope analysis of biogenic opal from lake sediments, from the Allerod/Younger Dryas transition in a core from Linsley Pond, Connecticut, gives an average estimate of a 6 C drop in temperature during the Younger Dryas. This shift represents temperatures during the bloom season, and may be less than the winter temperature drop. The sharp transition itself, with a duration of about 200 years, suggests that the temperature decrease may have been as large as 12 C. Previous estimates of the Allerod/Younger Dryas temperature shifts are controversial, and range from 3-20 C, suggesting that further interdisciplinary research on the same samples is warranted. One way that global climate change manifests itself is by redistributing energy throughout the globe. The Northern Hemisphere latitudinal temperature gradient during the late-glacial is at present a controversial topic. The magnitude of air temperature shifts during the Allerod/Younger Dryas (YD) oscillation are estimated from mid-latitude pollen records surrounding the North Atlantic to be 3-5 C in Europe [Lowe et al., 19941 and 3-4 C in the eastern US [Peteet et al., 1993]. In contrast, lake temperatures estimates derived from aquatic midge larvae in the Canadian eastern maritimes and Maine range from 6-20 C, with larger shifts at more southern sites [Levesque et al., 1997]. The magnitude of YD cooling in Greenland ice cores ranges from at least 7 C from the Bolling warming [Dansgaard et al., 1989] to 15 C - a more recent estimate from borehole temperatures [Cuffey et al., 1995]. The ice core geochemical records reveal that massive frequent and short-term (decadal or less) changes in atmospheric composition occurred throughout this event, suggesting a very dynamic circulation [Mayewski et al., 1993).

  8. Stable isotope analysis of energy dynamics in aquatic ecosystems suggests trophic shifts following severe wildfire

    NASA Astrophysics Data System (ADS)

    Martens, A. M.; Silins, U.; Bladon, K. D.; Williams, C.; Wagner, M. J.; Luchkow, E.

    2015-12-01

    Wildfire alters landscapes and can have significant impacts on stream ecosystems. The 2003 Lost Creek wildfire was one of the most severe on Alberta's eastern rocky mountain slopes, resulting in elevated sediment production and nutrient (phosphorus, nitrogen, and carbon) export in impacted streams. These resulted in increased algal productivity and macroinvertebrate abundance and diversity, and as a result, fish in watersheds draining wildfire affected catchments were larger than those in the same age class from reference (unburned) watersheds. In the present investigation, stable isotope analysis of C and N was utilized to evaluate ecosystem energy dynamics and describe trophic relationships in those watersheds. Aquatic invertebrates from burned catchments showed enrichment in δ13C and δ15N relative to algae suggesting a reliance on algae (autochthony) as a primary source of energy. Invertebrates from unburned systems were depleted in δ13C relative to algae indicating reliance on allochthonous or terrestrial primary energy sources. Preliminary analysis of δ15N in macroinvertebrates showed slight enrichment in burned catchments suggesting a trophic shift. More comprehensive macroinvertebrate sampling and identification has been conducted; isotopic analysis will provide greater resolution of how specific families within feeding guilds have been affected by wildfire. This will provide more robust insights into how wildfires may impact stream ecology in mountain environments.

  9. Theoretical analysis of geometry and NMR isotope shift in hydrogen-bonding center of photoactive yellow protein by combination of multicomponent quantum mechanics and ONIOM scheme.

    PubMed

    Kanematsu, Yusuke; Tachikawa, Masanori

    2014-11-14

    Multicomponent quantum mechanical (MC_QM) calculation has been extended with ONIOM (our own N-layered integrated molecular orbital + molecular mechanics) scheme [ONIOM(MC_QM:MM)] to take account of both the nuclear quantum effect and the surrounding environment effect. The authors have demonstrated the first implementation and application of ONIOM(MC_QM:MM) method for the analysis of the geometry and the isotope shift in hydrogen-bonding center of photoactive yellow protein. ONIOM(MC_QM:MM) calculation for a model with deprotonated Arg52 reproduced the elongation of O-H bond of Glu46 observed by neutron diffraction crystallography. Among the unique isotope shifts in different conditions, the model with protonated Arg52 with solvent effect reasonably provided the best agreement with the corresponding experimental values from liquid NMR measurement. Our results implied the availability of ONIOM(MC_QM:MM) to distinguish the local environment around hydrogen bonds in a biomolecule.

  10. Theoretical analysis of geometry and NMR isotope shift in hydrogen-bonding center of photoactive yellow protein by combination of multicomponent quantum mechanics and ONIOM scheme

    SciTech Connect

    Kanematsu, Yusuke; Tachikawa, Masanori

    2014-11-14

    Multicomponent quantum mechanical (MC-QM) calculation has been extended with ONIOM (our own N-layered integrated molecular orbital + molecular mechanics) scheme [ONIOM(MC-QM:MM)] to take account of both the nuclear quantum effect and the surrounding environment effect. The authors have demonstrated the first implementation and application of ONIOM(MC-QM:MM) method for the analysis of the geometry and the isotope shift in hydrogen-bonding center of photoactive yellow protein. ONIOM(MC-QM:MM) calculation for a model with deprotonated Arg52 reproduced the elongation of O–H bond of Glu46 observed by neutron diffraction crystallography. Among the unique isotope shifts in different conditions, the model with protonated Arg52 with solvent effect reasonably provided the best agreement with the corresponding experimental values from liquid NMR measurement. Our results implied the availability of ONIOM(MC-QM:MM) to distinguish the local environment around hydrogen bonds in a biomolecule.

  11. Variation in the isotopic composition of striped weakfish Cynoscion guatucupa of the Southwest Atlantic Ocean in response to dietary shifts.

    PubMed

    Viola, M N Paso; Riccialdelli, L; Jaureguizar, A; Panarello, H O; Cappozzo, H L

    2017-08-17

    The aim of this study was to analyze the isotopic composition in muscle of striped weakfish Cynoscion guatucupa from Southwest Atlantic Ocean in order to evaluate a possible variation in δ13C and δ15N in response to dietary shifts that occur as animals grow. We also explored for isotopic evidence of differences between sample locations. The results showed an agreement between isotope analysis and previous conventional studies. Differences in the isotope composition between sampling location were not observed. A positive relation exists between isotope values and total body length of the animals. The Cluster analysis defined three groups of size classes, validated by the MDS. Differences in the relative consumption of prey species in each size class were also observed performing isotope mixing models (SIAR). Variation in δ15N among size classes would be associated with the consumption of a different type of prey as animals grow. Small striped weakfish feed on small crustaceans and progressively increase their consumption of fish (anchovy, Engraulis anchoita), increasing by this way their isotope values. On the other hand, differences in δ13C values seemed to be related to age-class specific spatial distribution patterns. Therefore, large and small striped weakfish remain specialized but feeding on different prey at different trophic levels. These results contribute to the study of the diet of striped weakfish, improve the isotopic ecology models and highlight on the importance of accounting for variation in the isotopic composition in response to dietary shifts with the size of one of the most important fishery resources in the region.

  12. Isotope shifts in francium isotopes Fr 206 - 213 and Fr 221

    SciTech Connect

    Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Zhang, J.; Orozco, L. A.; Aubin, S.; Gomez, E.; FrPNC Collaboration

    2014-11-07

    We present the isotope shifts of the 7s1/2 to 7p1/2 transition for francium isotopes ²⁰⁶⁻²¹³Fr with reference to ²²¹Fr collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7s1/2 to 7p3/2 isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D₁ and D₂ transitions, of sufficient precision to differentiate between ab initio calculations.

  13. The superconducting gap ratio, isotope-shift exponent and pressure coefficient of Tc for high- Tc systems

    NASA Astrophysics Data System (ADS)

    Das, A. N.; Sarkar, Sujit

    1996-02-01

    The superconducting gap ratio, isotope-shift exponent and the pressure co-efficient of the superconducting transition temperature are studied within different models proposed for high- Tc cuprate oxide systems. A comparison with the experimental results of high- Tc oxide systems is made.

  14. LITERATURE SURVEY ON ISOTOPIC ABUNDANCE RATIO MEASUREMENTS - 2001-2005

    SciTech Connect

    HOLDEN, N.E.

    2005-08-13

    Along with my usual weekly review of the published literature for new nuclear data, I also search for new candidates for best measurements of isotopic abundances from a single source. Most of the published articles, that I previously had found in the Research Library at the Brookhaven Lab, have already been sent to the members of the Atomic Weights Commission, by either Michael Berglund or Thomas Walczyk. In the last few days, I checked the published literature for any other articles in the areas of natural variations in isotopic abundance ratios, measurements of isotopic abundance ratios on samples of extra-terrestrial material and isotopic abundance ratio measurements performed using ICPMS instruments. Hopefully this information will be of interest to members of the Commission, the sub-committee on isotopic abundance measurements (SIAM), members of the former sub-committee on natural isotopic fractionation (SNIF), the sub-committee on extra-terrestrial isotope ratios (SETIR), the RTCE Task Group and the Guidelines Task Group, who are dealing with ICPMS and TIMS comparisons. In the following report, I categorize the publications in one of four areas. Measurements performed using either positive or negative ions with Thermal Ionization Mass Spectrometer, TIMS, instruments; measurements performed on Inductively Coupled Plasma Mass Spectrometer, ICPMS, instruments; measurements of natural variations of the isotopic abundance ratios; and finally measurements on extra-terrestrial samples with instrumentation of either type. There is overlap in these areas. I selected out variations and ET results first and then categorized the rest of the papers by TIMS and ICPMS.

  15. Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth

    PubMed Central

    2017-01-01

    In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed 15N-enriched algae (0.4–5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies. PMID:28405367

  16. Shifts in rotifer life history in response to stable isotope enrichment: testing theories of isotope effects on organismal growth.

    PubMed

    Gorokhova, Elena

    2017-03-01

    In ecology, stable isotope labelling is commonly used for tracing material transfer in trophic interactions, nutrient budgets and biogeochemical processes. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism growth and metabolism. This assumption is, however, challenged by theoretical considerations and experimental studies on kinetic isotope effects in vivo. Here, I demonstrate profound changes in life histories of the rotifer Brachionus plicatilis fed (15)N-enriched algae (0.4-5.0 at%); i.e. at the enrichment levels commonly used in ecological studies. These findings support theoretically predicted effects of heavy isotope enrichment on growth, metabolism and ageing in biological systems and underline the importance of accounting for such effects when using stable isotope labelling in experimental studies.

  17. The vibrational spectra of amides—II. The force field and isotopic shifts of N, N-dimethyl formamide

    NASA Astrophysics Data System (ADS)

    Steele, D.; Quatermain, A.

    The effects of 16O → 18O substitution on the vibrational frequencies of N, N-dimethylformamide have been studied. To understand these and the effects of previously measured shift data due to 13C, 2H and 15N ab initio calculations of frequencies and intensities have been carried out at the 3-21G level. Accord between theory and experiment is generally good. A surprising result is the prediction of a weak band near 2000 cm -1 in DMF due to in-plane interaction between the methyl umbrella modes and the anti-symmetric CN stretch. This abnormally high frequency is explained as arising due to the planar trigonal C 3N entity. Previous problems in reproducing isotope shifts are shown to be due to this mode being previously assigned near 1500 cm -1. The effects of suppressing reference to one of a set of internal valence angles involved in a redundancy are explored. It is shown that the principal effect is to add the diagonal quadratic constant for that coordinate to all other quadratic terms involving pairs of the angles involved in the redundancy. This results in large, almost equal, interaction constants amongst this set. Such effects are seen in the present work. The ab initio field is shown to be compatible with ab initio fields of mono N-methyl amides extant in the literature.

  18. H/D isotope effects on NMR chemical shifts of nuclei involved in a hydrogen bridge of hydrogen isocyanide complexes with fluoride anion.

    PubMed

    Golubev, Nikolai S; Detering, Carsten; Smirnov, Sergei N; Shenderovich, Ilja G; Denisov, Gleb S; Limbach, Hans-Heinrich; Tolstoy, Peter M

    2009-07-07

    (1)H, (2)H, (19)F and (15)N NMR spectra of a strongly hydrogen-bonded anionic cluster, CNHF(-), as an ion pair with a tetrabutylammonium cation dissolved in CDF(3)-CDF(2)Cl mixture were recorded in the slow exchange regime at temperatures down to 110 K. The fine structure due to spin-spin coupling of all nuclei involved in the hydrogen bridge was resolved. H/D isotope effects on the chemical shifts were measured. The results were compared with those obtained earlier for a similar anion, FHF(-), and interpreted via ab initio calculations of magnetic shielding as functions of internal vibrational coordinates, namely an anti-symmetric proton stretching and a doubly-degenerate bending. The values of primary and secondary isotope effects on NMR chemical shifts were estimated using a power expansion of the shielding surface as a function of vibrational coordinates. A positive primary isotope effect was explained as a result of the decrease of the hydron stretching amplitude upon deuteration. We show that the proton shielding surface has a minimum close to the equilibrium geometry of the CNHF(-) anion, leading to the positive primary H/D isotope effect in a rather asymmetric hydrogen bond. We conclude that caution should be used when making geometric estimations on the basis of NMR data, since the shapes of the shielding functions of the internal vibrational coordinates can be rather exclusive for each complex.

  19. Measurement and Calibration of PSD with Phase-shifting Interferometers

    NASA Technical Reports Server (NTRS)

    Lehan, J. P.

    2008-01-01

    We discuss the instrumental aspects affecting the measurement accuracy when determining PSD with phase shifting interferometers. These include the source coherence, optical train effects, and detector effects. The use of a carefully constructed calibration standard will also be discussed. We will end with a recommended measurement and data handling procedure.

  20. Ion microprobe isotopic measurements of individual interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Mckeegan, K. D.; Walker, R. M.; Zinner, E.

    1985-01-01

    The results of the first extended ion probe study of interplanetary dust particles (IDPs) are reported. The analytic procedures and the current limits on the precision and accurary of isotopic measurements of light elements are discussed in considerable detail. It is shown that isotopic measurements of several elements can be made on different individual fragments of a single IDP of 10-15 microns in size. The deuterium enrichments observed in several of the particles are shown to be intrinsic, providing independent proof that the particles are extraterrestrial. Carbon isotopic measurements on fragments of three IDPs give ratios similar to terrestrial values and show a largely uniform isotopic composition for a given particle. Small, but significant, differences in delta C-13 of about 40 percent between particles are seen.

  1. Line shift, line asymmetry, and the ^6Li/^7Li isotopic ratio determination

    NASA Astrophysics Data System (ADS)

    Cayrel, R.; Steffen, M.; Chand, H.; Bonifacio, P.; Spite, M.; Spite, F.; Petitjean, P.; Ludwig, H.-G.; Caffau, E.

    2007-10-01

    Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such asymmetries are usually neglected in abundance analyses. The determination of the ^6Li/^7Li isotopic ratio is prone to suffering from such asymmetries, as the contribution of ^6Li is a slight blending reinforcement of the red wing of each component of the corresponding ^7Li line, with respect to its blue wing. Aims: The present paper studies the halo star HD 74000 and estimates the impact of convection-related asymmetries on the Li isotopic ratio determination. Methods: Two methods are used to meet this aim. The first, which is purely empirical, consists in deriving a template profile from another element that can be assumed to originate in the same stellar atmospheric layers as Li I, producing absorption lines of approximately the same equivalent width as individual components of the ^7Li I resonance line. The second method consists in conducting the abundance analysis based on NLTE line formation in a 3D hydrodynamical model atmosphere, taking into account the effects of photospheric convection. Results: The results of the first method show that the convective asymmetry generates an excess absorption in the red wing of the ^7Li absorption feature that mimics the presence of ^6Li at a level comparable to the hitherto published values. This opens the possibility that only an upper limit on ^6Li/^7Li has thus far been derived. The second method confirms these findings. Conclusions: From this work, it appears that a systematic reappraisal of former determinations of ^6Li abundances in halo stars is warranted. Based on observations carried out at the European Southern Observatory (ESO), under prog. ID 75.D-0600. Tables 1-3, and additional references are only available in electronic form at http://www.aanda.org

  2. Measuring Isotope Ratios Across the Solar System

    NASA Technical Reports Server (NTRS)

    Webster, Chris R.; Mahaffy, Paul R.

    2012-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

  3. Measuring Isotope Ratios Across the Solar System

    NASA Technical Reports Server (NTRS)

    Webster, Chris R.; Mahaffy, Paul R.

    2012-01-01

    Stable isotope ratios in C, H, N, O and S are powerful indicators of a wide variety of planetary geophysical processes that can identify origin, transport, temperature history, radiation exposure, atmospheric escape, environmental habitability and biology [1]. For the Allan Hills 84001 meteorite, for example, the (sup 1)(sup 3)C/(sup 1)(sup 2)C ratio identifies it as a Mars (SNC) meteorite; the ??K/??Ar ratio tells us the last time the rock cooled to solid, namely 4 Gya; isotope ratios in (sup 3)He, (sup 2)(sup 1)Ne and (sup 3)?Ar show it was in space (cosmic ray exposure) for 10-20 million years; (sup 1)?C dating that it sat in Antarctica for 13,000 years before discovery; and clumped isotope analysis of (sup 1)?O(sup 1)(sup 3)C(sup 1)?O in its carbonate that it was formed at 18+/-4 ?C in a near-surface aqueous environment [2]. Solar System Formation

  4. Displacement measurement using a wavelength-phase-shifting grating interferometer.

    PubMed

    Lee, Ju-Yi; Jiang, Geng-An

    2013-10-21

    A grating interferometer based on the wavelength-modulated phase-shifting method for displacement measurements is proposed. A laser beam with sequential phase shifting can be accomplished using a wavelength-modulated light passing through an unequal-path-length optical configuration. The optical phase of the moving grating is measured by the wavelength-modulated phase-shifting technique and the proposed time-domain quadrature detection method. The displacement of the grating is determined by the grating interferometry theorem with the measured phase variation. Experimental results reveal that the proposed method can detect a displacement up to a large distance of 1 mm and displacement variation down to the nanometer range.

  5. Using Tensor Light Shifts to Measure and Cancel a Cell's Quadruopolar Frequency Shift

    NASA Astrophysics Data System (ADS)

    Hunter, Larry; Peck, Stephen; Lane, Nathanael; Ang, Daniel

    2016-05-01

    We have developed a new technique that uses the tensor light shift to measure and cancel the frequency shift produced by the quadrupolar anisotropy of a vapor cell. We demonstrate the technique on the 6 S1/2, F = 4 level of Cs using the D1 transition. The method extends our ability to study quadrupolar wall interactions beyond diamagnetic atoms. We have deduced the twist angle per wall adhesion for cesium on an alkene coating to be about 1.4 mrad. This value is about 37 times larger than the twist angle observed in 131 Xe, suggesting that it is not produced by the interaction of the nuclear quadrupole moment with a collisional electric-field gradient. Alternative mechanisms that may be responsible for the observed quadrupolar frequency shifts are discussed. By cancelling the cell-induced quadrupole shift we have extended our cells' effective spin-relaxation times by as much as a factor of two. This cancellation improves magnetometer sensitivity in highly anisotropic cells and could reduce systematic uncertainties in some precision measurements. This work was supported by NSF Grant No. PHY1205824 and No. PHY1519265.

  6. Using tensor light shifts to measure and cancel a cell's quadrupolar frequency shift

    NASA Astrophysics Data System (ADS)

    Peck, S. K.; Lane, N.; Ang, D. G.; Hunter, L. R.

    2016-02-01

    We have developed a technique that uses the tensor light shift to measure and cancel the frequency shift produced by the quadrupolar anisotropy of a vapor cell. We demonstrate the technique on the 6 S1 /2 ,F =4 level of Cs using the D1 transition. The method extends our ability to study quadrupolar wall interactions beyond diamagnetic atoms. We have deduced the twist angle per wall adhesion for cesium on an alkene coating to be θCs -alkene=1.4 mrad . This value is about 37 times larger than the twist angle observed in 131Xe, suggesting that it is not produced by the interaction of the nuclear quadrupole moment with a collisional electric-field gradient. Alternative mechanisms that may be responsible for the observed quadrupolar frequency shifts are discussed. By canceling the cell-induced quadrupole shift we have extended our cells' effective spin-relaxation times by as much as a factor of 2. This cancellation improves magnetometer sensitivity in highly anisotropic cells and could reduce systematic uncertainties in some precision measurements.

  7. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

    2013-01-01

    Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction.

  8. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

    PubMed Central

    Wallner, A.; Melber, K.; Merchel, S.; Ott, U.; Forstner, O.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.

    2013-01-01

    Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction. PMID:23565017

  9. MG Isotopic Measurement of FIB-Isolated Presolar Silicate Grains

    NASA Technical Reports Server (NTRS)

    Messenger, Scott R.; Nguyen, A.; Ito, M.; Rahman, Z.

    2010-01-01

    The majority of presolar oxide and silicate grains are ascribed to origins in low-mass red giant and asymptotic giant branch (AGB) stars based on their O isotopic ratios. However, a minor population of these grains (< 10%) has O isotopic ratios incompatible with these sources. Two principle alternative sources are higher-than-solar metallicity (Z) stars or, more likely, supernovae (SN) [1-3]. These rare (Group 4) grains [3] are characterized by enrichments in O-18, and typically also enrichments in O-17. An even rarer subset of grains with extremely large enrichments in O-17 and smaller depletions in O-18 were suggested to come from binary star systems [2]. To establish the origins of these isotopically unusual grains, it is necessary to examine isotopic systems in addition to O. Presolar silicates offer several elements diagnostic of their stellar sources and nuclear processes, including O, Si, Mg, Fe and Ca. However, the database for minor element isotopic compositions in silicates is seriously lacking. To date only two silicate grains have been analyzed for Mg [4] or Fe [5]. One major complicating factor is their small size (average 230 nm), which greatly limits the number of measurements that can be performed on any one grain and makes it more difficult to obtain statistically relevant data. This problem is compounded because the grains are identified among isotopically solar silicates, which contribute a diluting signal in isotopic measurements [1]. Thus, relatively small isotopic anomalies are missed due to this dilution effect. By applying focused ion beam (FIB) milling, we obtain undiluted Mg isotopic ratios of isolated rare presolar silicate grains to investigate their sources.

  10. Continuous in situ measurements of stable isotopes in liquid water

    NASA Astrophysics Data System (ADS)

    Herbstritt, Barbara; Gralher, Benjamin; Weiler, Markus

    2012-03-01

    We developed a method to measure in situ the isotopic composition of liquid water with minimal supervision and, most important, with a temporal resolution of less than a minute. For this purpose a microporous hydrophobic membrane contactor (Membrana) was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with N2 as a carrier gas in order to transform a small fraction of liquid water to water vapor. The generated water vapor was then analyzed continuously by the Picarro analyzer. To prove the membrane's applicability, we determined the specific isotope fractionation factor for the phase change through the contactor's membrane across an extended temperature range (8°C-21°C) and with different waters of known isotopic compositions. This fractionation factor is needed to subsequently derive the liquid water isotope ratio from the measured water vapor isotope ratios. The system was tested with a soil column experiment, where the isotope values derived with the new method corresponded well (R2 = 0.998 for δ18O and R2 = 0.997 for δ2H) with those of liquid water samples taken simultaneously and analyzed with a conventional method (cavity ring-down spectroscopy). The new method supersedes taking liquid samples and employs only relatively cheap and readily available components. This makes it a relatively inexpensive, fast, user-friendly, and easily reproducible method. It can be applied in both the field and laboratory wherever a water vapor isotope analyzer can be run and whenever real-time isotope data of liquid water are required at high temporal resolution.

  11. Uranium Isotopes as an Indicator of the Dead Sea Response to Holocene Climate Shifts

    NASA Astrophysics Data System (ADS)

    Sweeney, J.; Kiro, Y.; Goldstein, S. L.

    2016-12-01

    The Dead Sea is a terminal hypersaline lake whose watershed is located within two distinct climate zones: the Mediterranean and the Sahara-Arabian. With no natural outflows, the Dead Sea composition and level are sensitive to changes in climate. A 450 m core collected as part of the ICDP-Dead Sea Deep Drilling Project in 2010-11 provides a record of climate in the Levant over the last 220,000 years. The lithology of the core and the isotopic ratios of the authigenic minerals reflect shifts between a wetter glacial climate and more arid interglacial periods. The Holocene, a relatively dry period in the Levant, is marked by thick intervals of halite, gypsum, and detritus, while the wetter glacial periods are marked by aragonite, detritus, and gypsum. Here, we present 234U/238U data on deglacial and Holocene age aragonite and halite samples, as well as modern water sources from around the Dead Sea. Water sources in the Dead Sea drainage basin have variable 234U/238U activity ratios, ranging from 1.5 for the Jordan River and western sources to 1.1 for floods and eastern sources. Therefore, the 234U/238U activity ratios recorded in the authigenic minerals reflect changes in lake composition that resulted from variations in the relative contributions of different water sources. The 234U/238U activity ratios in the authigenic phases during the Holocene show that, in general, the contribution of water to the Dead Sea was similar to the present-day and mainly through the Jordan River. However, there is substantial variability, indicating intervals of drought, marked by decreased Jordan River runoff and increased importance of floods and eastern sourced runoff. An extreme example occurred near the beginning of the Holocene at 10 ka, marked by a significant thickness of halite and where the 234U/238U activity shifts to very low values <1.2, indicating a severe drought.

  12. In-plane displacement measurement using optical vortex phase shifting.

    PubMed

    Sun, Haibin; Wang, Xinghai; Sun, Ping

    2016-07-20

    In this paper, we propose a new method for in-plane displacement measurement by application of phase shifting based on an optical vortex. The phase shifts are obtained by displaying computer-generated fork holograms on the screen of a liquid-crystal spatial light modulator (LC-SLM). Furthermore, the vortex beam that is generated by the LC-SLM can be used as a reference light in the experiment. Eight speckle patterns with phase-shift increments of 0, π/2, π, and 3π/2 were captured by a CCD camera before and after the deformation. The displacement of the deformed object was obtained by unwrapping. Experimental results demonstrated the efficacy of the proposed method for in-plane displacement measurement.

  13. Isotopic evidence for an early shift to C4 resources by Pliocene hominins in Chad

    PubMed Central

    Lee-Thorp, Julia; Likius, Andossa; Mackaye, Hassane T.; Vignaud, Patrick; Sponheimer, Matt; Brunet, Michel

    2012-01-01

    Foods derived from C4 plants were important in the dietary ecology of early Pleistocene hominins in southern and eastern Africa, but the origins and geographic variability of this relationship remain unknown. Carbon isotope data show that Australopithecus bahrelghazali individuals from Koro Toro in Chad are significantly enriched in 13C, indicating a dependence on C4 resources. As these sites are over 3 million years in age, the results extend the pattern of C4 dependence seen in Paranthropus boisei in East Africa by more than 1.5 million years. The Koro Toro hominin fossils were found in argillaceous sandstone levels along with abundant grazing and aquatic faunal elements that, in combination, indicate the presence of open to wooded grasslands and stream channels associated with a greatly enlarged Lake Chad. In such an environment, the most abundant C4 plant resources available to A. bahrelghazali were grasses and sedges, neither of which is usually considered as standard great ape fare. The results suggest an early and fundamental shift in hominin dietary ecology that facilitated the exploitation of new habitats. PMID:23150583

  14. Isotopic evidence for an early shift to C₄ resources by Pliocene hominins in Chad.

    PubMed

    Lee-Thorp, Julia; Likius, Andossa; Mackaye, Hassane T; Vignaud, Patrick; Sponheimer, Matt; Brunet, Michel

    2012-12-11

    Foods derived from C(4) plants were important in the dietary ecology of early Pleistocene hominins in southern and eastern Africa, but the origins and geographic variability of this relationship remain unknown. Carbon isotope data show that Australopithecus bahrelghazali individuals from Koro Toro in Chad are significantly enriched in (13)C, indicating a dependence on C(4) resources. As these sites are over 3 million years in age, the results extend the pattern of C(4) dependence seen in Paranthropus boisei in East Africa by more than 1.5 million years. The Koro Toro hominin fossils were found in argillaceous sandstone levels along with abundant grazing and aquatic faunal elements that, in combination, indicate the presence of open to wooded grasslands and stream channels associated with a greatly enlarged Lake Chad. In such an environment, the most abundant C(4) plant resources available to A. bahrelghazali were grasses and sedges, neither of which is usually considered as standard great ape fare. The results suggest an early and fundamental shift in hominin dietary ecology that facilitated the exploitation of new habitats.

  15. Blood oxyhemoglobin saturation measurements by blue-green spectral shift.

    PubMed

    Denninghoff, Kurt R; Chipman, Russell A; Hillman, Lloyd W

    2007-01-01

    Previous work describing a resilient method for measuring oxyhemoglobin saturation using the blue-green spectral shift was performed using cell free hemoglobin solutions. Hemoglobin solution and whole blood sample spectra measured under similar conditions in a spectrophotometer are used here to begin evaluating the impact of cellular scattering on this method. The blue-green spectral shift with changing oxyhemoglobin saturation was preserved in these blood samples and the blue-green spectral shift was relatively unaffected by physiological changes in blood pH (6.6, 7.1, and 7.4), path length through blood (100 and 200 microm), and blood hematocrit (19 to 48%). The packaging of hemoglobin in red blood cells leads to a decreased apparent path length through hemoglobin, and an overall decrease in scattering loss with increasing wavelength from 450 to 850 nm. The negative slope of the scattering loss in the 476 to 516-nm range leads to a +3.0 nm shift in the oxyhemoglobin saturation calibration line when the blue-green spectral minimum in these blood samples was compared to cell free hemoglobin. Further research is needed to fully evaluate the blue green spectral shift method in cellular systems including in vivo testing.

  16. Hydrogen maser - Measurement of wall shift with a flexible bulb

    NASA Technical Reports Server (NTRS)

    Brenner, D.

    1970-01-01

    Flexible bulb is squeezed to change mean free path of hydrogen atoms, and to change bulb's volume without changing its surface area. Volumes in the different configurations are measured to learn the change in mean free path and calculate wall shift. Various bulb coating materials are described.

  17. Quantitative estimates of precision for molecular isotopic measurements.

    PubMed

    Jasper, J P

    2001-01-01

    At least three methods of calculating the random errors or variance of molecular isotopic data are presently in use. The major components of variance are differentiated and quantified here into least three to four individual components. The measurement of error of the analyte relative to a working (whether an internal or an external) standard is quantified via the statistical pooled estimate of error. A statistical method for calculating the total variance associated with the difference of two individual isotopic compositions from two isotope laboratories is given, including the variances of the laboratory (secondary) and working standards, as well as those of the analytes. An abbreviated method for estimation of of error typical for chromatographic/isotope mass spectrometric methods is also presented. Copyright 2001 John Wiley & Sons, Ltd.

  18. Guide to plutonium isotopic measurements using gamma-ray spectrometry

    SciTech Connect

    Lemming, J.F.; Rakel, D.A.

    1982-08-26

    Purpose of this guide is to assist those responsible for plutonium isotopic measurements in the application of gamma-ray spectrometry. Objectives are to promote an understanding of the measurement process, including its limitations and applicability, by reviewing the general features of a plutonium spectrum and identifying the quantities which must be extracted from the data; to introduce state-of-the-art analysis techniques by reviewing four isotopic analysis packages and identifying their differences; to establish the basis for measurement control and assurance by discussing means of authenticating the performance of a measurement system; and to prepare for some specific problems encountered in plutonium isotopic analyses by providing solutions from the practical experiences of several laboratories. 29 references, 12 figures, 17 tables.

  19. Interferometric method to measure the Goos-Hänchen shift.

    PubMed

    Prajapati, Chandravati; Ranganathan, Dilip; Joseph, Joby

    2013-04-01

    We propose and demonstrate an interferometric method to measure the Goos-Hänchen (GH) shift, which is based on observing the interference between p- and s-polarized beams. In our method both p- and s-polarized beams are observed simultaneously and across the entire beam profile. To demonstrate our method, we measured the GH shift of aluminum (Al) and glass at different values of the incidence angle ranging from 20° to 70°, with a helium-neon laser as source. We compared the experimental result with theoretical calculations and found a good agreement between them. Our method also enables us to measure the GH shift at any point across the entire beam profile, for arbitrary beam profiles. This is not possible with the methods currently in use. We presented the observed values for the Gaussian mode used, which enables us to find the relative shifts between the p and s components at various points on the incident profile after reflection.

  20. Fossil Mice and Rats Show Isotopic Evidence of Niche Partitioning and Change in Dental Ecomorphology Related to Dietary Shift in Late Miocene of Pakistan

    PubMed Central

    Kimura, Yuri; Jacobs, Louis L.; Cerling, Thure E.; Uno, Kevin T.; Ferguson, Kurt M.; Flynn, Lawrence J.; Patnaik, Rajeev

    2013-01-01

    Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C3 and C4 dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C3 forest and woodland to C4 savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (δ13C) with dental morphology of murine rodents, spanning 13.8 to ∼2.0 Ma, across the C3 to C4 vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive δ13C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C4 diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible. PMID:23936324

  1. Fossil mice and rats show isotopic evidence of niche partitioning and change in dental ecomorphology related to dietary shift in Late Miocene of Pakistan.

    PubMed

    Kimura, Yuri; Jacobs, Louis L; Cerling, Thure E; Uno, Kevin T; Ferguson, Kurt M; Flynn, Lawrence J; Patnaik, Rajeev

    2013-01-01

    Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C3 and C4 dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C3 forest and woodland to C4 savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (δ(13)C) with dental morphology of murine rodents, spanning 13.8 to ∼2.0 Ma, across the C3 to C4 vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive δ(13)C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C4 diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible.

  2. Continuous on-line water vapor isotope measurements in Antarctica

    NASA Astrophysics Data System (ADS)

    Landsberg, Janek; Romanini, Daniele; Holmen, Kim; Isaksson, Elisabeth; Meijer, Harro; Kerstel, Erik

    2010-05-01

    In the context of a globally warming climate it is crucial to study the climate variability in the past and to understand the underlying mechanisms (1). Precipitation deposited on the polar ice caps provides a means to retrieve information on temperature changes (through the paleo-temperature dependence of the isotopic composition of the ice) and atmospheric composition (of gas stored in bubbles in the ice) on time scales from one to almost one million years, with sub-annual resolution in the most recent centuries. However, it is now widely recognized that the calibration of the paleo-thermometer is highly problematic. For this reason attempts to model the global water cycle, including the isotope signals, are ongoing with the aim of providing a more physical basis of the isotope - temperature relation. Currently, there is a large divergence in the results obtained by different modeling strategies. The missing link in these model studies is their forcing by experimental data on the pre-deposition isotopic composition of the vapor phase compartment of the hydrological cycle. We propose to measure the isotopic composition of moisture carried towards and deposited on Antarctica, in order to constrain the numerical models. In this context we are developing a modified, more sensitive and precise, version of a laser water vapor isotope spectrometer, originally designed for stratospheric studies (2, 3). This instrument, which will first be operated at the Norwegian station of Troll in Queen Maud Land, will enable the continuous, online measurement of all three stable isotope ratios of atmospheric water vapor. So far, such data is non-existent. Our data should improve the validity of the models and improve the understanding of the physical mechanisms at the basis of the isotope thermometer. This in turn will lead to an increased confidence in the predictions of (general circulation) models concerning climate variability. (1) International Panel on Climate Change (IPCC), 4

  3. Facial Soft Tissue Measurement in Microgravity-induces Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Marshburn, Thomas; Cole, Richard; Pavela, James; Garcia, Kathleen; Sargsyan, Ashot

    2014-01-01

    Fluid shifts are a well-known phenomenon in microgravity, and one result is facial edema. Objective measurement of tissue thickness in a standardized location could provide a correlate with the severity of the fluid shift. Previous studies of forehead tissue thickness (TTf) suggest that when exposed to environments that cause fluid shifts, including hypergravity, head-down tilt, and high-altitude/lowpressure, TTf changes in a consistent and measurable fashion. However, the technique in past studies is not well described or standardized. The International Space Station (ISS) houses an ultrasound (US) system capable of accurate sub-millimeter measurements of TTf. We undertook to measure TTf during long-duration space flight using a new accurate, repeatable and transferable technique. Methods: In-flight and post-flight B-mode ultrasound images of a single astronaut's facial soft tissues were obtained using a Vivid-q US system with a 12L-RS high-frequency linear array probe (General Electric, USA). Strictly mid-sagittal images were obtained involving the lower frontal bone, the nasofrontal angle, and the osseo-cartilaginous junction below. Single images were chosen for comparison that contained identical views of the bony landmarks and identical acoustical interface between the probe and skin. Using Gingko CADx DICOM viewing software, soft tissue thickness was measured at a right angle to the most prominent point of the inferior frontal bone to the epidermis. Four independent thickness measurements were made. Conclusions: Forehead tissue thickness measurement by ultrasound in microgravity is feasible, and our data suggest a decrease in tissue thickness upon return from microgravity environment, which is likely related to the cessation of fluid shifts. Further study is warranted to standardize the technique with regard to the individual variability of the local anatomy in this area.

  4. Defining uncertainty and error in planktic foraminiferal oxygen isotope measurements

    NASA Astrophysics Data System (ADS)

    Fraass, A. J.; Lowery, C. M.

    2017-02-01

    Foraminifera are the backbone of paleoceanography. Planktic foraminifera are one of the leading tools for reconstructing water column structure. However, there are unconstrained variables when dealing with uncertainty in the reproducibility of oxygen isotope measurements. This study presents the first results from a simple model of foraminiferal calcification (Foraminiferal Isotope Reproducibility Model; FIRM), designed to estimate uncertainty in oxygen isotope measurements. FIRM uses parameters including location, depth habitat, season, number of individuals included in measurement, diagenesis, misidentification, size variation, and vital effects to produce synthetic isotope data in a manner reflecting natural processes. Reproducibility is then tested using Monte Carlo simulations. Importantly, this is not an attempt to fully model the entire complicated process of foraminiferal calcification; instead, we are trying to include only enough parameters to estimate the uncertainty in foraminiferal δ18O records. Two well-constrained empirical data sets are simulated successfully, demonstrating the validity of our model. The results from a series of experiments with the model show that reproducibility is not only largely controlled by the number of individuals in each measurement but also strongly a function of local oceanography if the number of individuals is held constant. Parameters like diagenesis or misidentification have an impact on both the precision and the accuracy of the data. FIRM is a tool to estimate isotopic uncertainty values and to explore the impact of myriad factors on the fidelity of paleoceanographic records, particularly for the Holocene.

  5. Defining Uncertainty and Error in Planktic Foraminiferal Oxygen Isotope Measurements

    NASA Astrophysics Data System (ADS)

    Fraass, A. J.; Lowery, C.

    2016-12-01

    Foraminifera are the backbone of paleoceanography, and planktic foraminifera are one of the leading tools for reconstructing water column structure. Currently, there are unconstrained variables when dealing with the reproducibility of oxygen isotope measurements. This study presents the first results from a simple model of foraminiferal calcification (Foraminiferal Isotope Reproducibility Model; FIRM), designed to estimate the precision and accuracy of oxygen isotope measurements. FIRM produces synthetic isotope data using parameters including location, depth habitat, season, number of individuals included in measurement, diagenesis, misidentification, size variation, and vital effects. Reproducibility is then tested using Monte Carlo simulations. The results from a series of experiments show that reproducibility is largely controlled by the number of individuals in each measurement, but also strongly a function of local oceanography if the number of individuals is held constant. Parameters like diagenesis or misidentification have an impact on both the precision and the accuracy of the data. Currently FIRM is a tool to estimate isotopic error values best employed in the Holocene. It is also a tool to explore the impact of myriad factors on the fidelity of paleoceanographic records. FIRM was constructed in the open-source computing environment R and is freely available via GitHub. We invite modification and expansion, and have planned inclusions for benthic foram reproducibility and stratigraphic uncertainty.

  6. Adsorption of H/sub 2/ isotopes on ZnO: coverage induced ir frequency shifts and adsorbate geometry. Technical report

    SciTech Connect

    Griffin, G.L.; Yates, J.T. Jr.

    1982-02-01

    The coverage dependence of the IR stretching frequencies for dissociative Type I adsorption of H2 and D2 on ZnO powders has been measured using transmission IR spectroscopy. By comparing the frequency shifts observed when the isotopic composition of the adsorbate is varied at constant total coverage with the shifts observed when the total coverage of either pure component is varied, we can separate the dynamic and static contributions to the coverage induced frequency shifts. The ZnH and ZnD shifts are due primarily to electrodynamic interactions. The observed shifts are in good agreement with the Hammaker model for dynamic dipole-dipole interactions, if adsorption is assumed to occur on (2 x 2) reconstructed ZnO (0001) surface planes. In contrast, the OH and OD shifts are due to electrostatic and inductive interactions. The electrostatic contribution can be estimated using a modification of Buckingham's treatment of local environment effects. A qualitative model, based on electron localization effects, is presented to explain the observed inductive contribution.

  7. Measurement of isotopic abundances in collected stratospheric ozone samples

    NASA Technical Reports Server (NTRS)

    Schueler, B.; Morton, J.; Mauersberger, K.

    1990-01-01

    Enrichment of heavy O3 isotopes has been measured in collected stratospheric samples. A balloon-borne cryogenic sampler was used to gather six O3 samples between 26 and 35 km in three flights. Subsequent laboratory mass spectrometer analysis of rare O3 isotopes at both mass 49 and 50 has resulted in more precise measurements than have previously been reported with in situ and ground-based techniques. In one flight, (O-50)3 was enriched by 12-16 percent and (O-49)3 by 9-11 percent, both increasing with altitude. In the remaining two flights, the isotope enrichment was nearly mass-independent at 8-9 percent. The enrichments in O3 at mass 50 are less than the large 40 percent value observed in some stratospheric measurements but similar to (O-49)3 and (O-50)3 fractionations produced in laboratory-generated ozone.

  8. Isotopic Resonance Hypothesis: Experimental Verification by Escherichia coli Growth Measurements

    PubMed Central

    Zubarev, Roman A.

    2015-01-01

    Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some “resonance” isotopic compositions, the kinetics increases, while at “off-resonance” compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error ±0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p ≪ 10−15). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas. PMID:25782666

  9. Isotopic resonance hypothesis: experimental verification by Escherichia coli growth measurements.

    PubMed

    Xie, Xueshu; Zubarev, Roman A

    2015-03-18

    Isotopic composition of reactants affects the rates of chemical and biochemical reactions. As a rule, enrichment of heavy stable isotopes leads to progressively slower reactions. But the recent isotopic resonance hypothesis suggests that the dependence of the reaction rate upon the enrichment degree is not monotonous. Instead, at some "resonance" isotopic compositions, the kinetics increases, while at "off-resonance" compositions the same reactions progress slower. To test the predictions of this hypothesis for the elements C, H, N and O, we designed a precise (standard error ±0.05%) experiment that measures the parameters of bacterial growth in minimal media with varying isotopic composition. A number of predicted resonance conditions were tested, with significant enhancements in kinetics discovered at these conditions. The combined statistics extremely strongly supports the validity of the isotopic resonance phenomenon (p ≪ 10(-15)). This phenomenon has numerous implications for the origin of life studies and astrobiology, and possible applications in agriculture, biotechnology, medicine, chemistry and other areas.

  10. A Framework Of Resilience Measures In Catastrophic Shift Systems

    NASA Astrophysics Data System (ADS)

    Srinivasan, V.; Kumar, P.

    2011-12-01

    Resilience of systems is an important attribute for understanding their behavior in an environment of change such as due to climate change or human impact. Yet, this notion has generally been used without precise quantitative measures. Resilience measures depend on the properties of both the system and the disturbance. We study resilience of the catastrophic shift system to develop mathematical measures of resilience. Catastrophic shift systems are archetype of systems that can maintain functional ability under disturbance, undergo sudden shifts to contrasting dynamic regimes under extreme stress and exhibit resistance to recovery. Therefore, the study of this system has broad applicability. We expand upon the existing notion of engineering and ecological resilience (defined as time to recovery of the system state following a disturbance event, and the amount of disturbance needed to push the system into an alternative regime) to develop new measures. We develop a number of measures for the catastrophic shift systems such as i) engineering resilience, ii) ecological resilience, iii) activation energy, iv) state recovery velocity, v) potential recovery velocity, vi) regime probability, vii) mode etc using a stochastic non-linear dynamical approach. We evaluate the behavior of these measures under Gaussian white noise and Markovian dichotomous noise. Different resilience measures yield different values for a given well-posed system-disturbance couple. Furthermore, a given resilience measure yields different values when the system is subject to different disturbances. An important capability of this quantitative formulation method is that it allows us to develop iso-resilience curves that can be used for control and maintenance of catastrophic shift systems. Iso-resilience curves connect points that have identical resilience values. These quantitative measures provide a unique opportunity for determining the optimum path of travel in the resilience landscape for

  11. Laser-resonance Lamb-shift measurement in hydrogenlike phosphorus

    NASA Astrophysics Data System (ADS)

    Pellegrin, P.; El Masri, Y.; Palffy, L.

    1985-01-01

    We report our final result on the Lamb-shift measurement in hydrogenlike phosphorous using the 2s1/2-2p3/2 laser-resonance method. From the measured value of the 2s1/2-2p3/2 energy splitting [539.60(20) THz, or 5555.8(2.0) Å] the Lamb shift S is deduced in the framework of Erickson's and Mohr's calculations. SEexpt and SMexpt are the results of the subtraction of the measured 2s1/2-2p3/2 energy splitting and the fine structure calculated by the two authors, respectively. The results, ||SE-SEexpt||=0.43+/- 0.20 THz and ||SM-SMexpt||=0.12+/- 0.20 THz, indicate agreement with Mohr's theoretical approach (SM) and are more than two standard deviations from Erickson's calculations (SE). A general overview on the experimental techniques and results is given. The general trend of the presently available experimental results on Lamb-shift measurements are compared with Mohr's calculations.

  12. A Portable, Field-Deployable Analyzer for Isotopic Water Measurements

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Gupta, M.; Huang, Y. W.; Lacelle, D.; McKay, C. P.; Fortson, S.

    2015-12-01

    Water stable isotopes have for many years been used to study the hydrological cycle, catchment hydrology, and polar climate among other applications. Typically, discrete water samples are collected and transported to a laboratory for isotope analysis. Due to the expense and labor associated with such sampling, isotope studies have generally been limited in scope and time-resolution. Field sampling of water isotopes has been shown in recent years to provide dense data sets with the increased time resolution illuminating substantially greater short term variability than is generally observed during discrete sampling. A truly portable instrument also opens the possibility to utilize the instrument as a tool for identifying which water samples would be particularly interesting for further laboratory investigation. To make possible such field measurements of liquid water isotopes, Los Gatos Research has developed a miniaturized, field-deployable liquid water isotope analyzer. The prototype miniature liquid water isotope analyzer (mini-LWIA) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology in a rugged, Pelican case housing for easy transport and field operations. The analyzer simultaneously measures both δ2H and δ18O from liquid water, with both manual and automatic water introduction options. The laboratory precision for δ2H is 0.6 ‰, and for δ18O is 0.3 ‰. The mini-LWIA was deployed in the high Arctic during the summer of 2015 at Inuvik in the Canadian Northwest Territories. Samples were collected from Sachs Harbor, on the southwest coast of Banks Island, including buried basal ice from the Lurentide Ice Sheet, some ice wedges, and other types of ground ice. Methodology and water analysis results from this extreme field deployment will be presented.

  13. Mass Spectrometric Measurement of Martian Krypton and Xenon Isotopic Abundance

    NASA Technical Reports Server (NTRS)

    Mahaffy, P.; Mauersberger, K.

    1993-01-01

    The Viking gas chromatograph mass spectrometer experiment provided significant data on the atmospheric composition at the surface of Mars, including measurements of several isotope ratios. However, the limited dynamic range of this mass spectrometer resulted in marginal measurements for the important Kr and Xe isotopic abundance. The Xe-129 to Xe-132 ratio was measured with an uncertainty of 70%, but none of the other isotope ratios for these species were obtained. Accurate measurement of the Xe and Kr isotopic abundance in this atmosphere provides an important data point in testing theories of planetary formation and atmospheric evolution. The measurement is also essential for a stringent test for the Martian origin of the SNC meteorites, since the Kr and Xe fractionation pattern seen in gas trapped in glassy nodules of an SNC (EETA 79001) is unlike any other known solar system resevoir. Current flight mass spectrometer designs combined with the new technology of a high-performance vacuum pumping system show promise for a substantial increase in gas throughput and the dynamic range required to accurately measure these trace species. Various aspects of this new technology are discussed.

  14. Measuring the antihydrogen Lamb shift with a relativistic antihydrogen beam

    SciTech Connect

    Blanford, G.; Gollwitzer, K.; Mandelkern, M.; Schultz, J.; Takei, G.; Zioulas, G.; Christian, D.C.; Munger, C.T.

    1998-06-01

    We propose an experiment to measure the Lamb shift and fine structure (the intervals 2s{sub 1/2}{minus}2p{sub 1/2} and 2p{sub 1/2}{minus}2p{sub 3/2}) in antihydrogen. A sample of 10000 antihydrogen atoms at a momentum of 8.85GeV/c suffices to measure the Lamb shift to 5{percent} and the fine structure to 1{percent}. Atomic collisions excite antihydrogen atoms to states with n=2; field ionization in a Lorentz-transformed laboratory magnetic field then prepares a particular n=2 state, and is used again to analyze that state after it is allowed to oscillate in a region of zero field. This experiment is feasible at Fermilab. {copyright} {ital 1998} {ital The American Physical Society}

  15. Stark Shift Measurement of Some Xe III Lines

    SciTech Connect

    Djurovic, S.; Cirisaif, M.; Pelaez, R. J.; Aparicio, J. A.; Mar, S.

    2008-10-22

    Examination of ionized xenon spectrum is of a great interest for plasma diagnostic purposes, theory testing and different applications. In this paper, we present Stark shift data for one blue and five UV Xe III lines. One line belongs to the 5d-6p transition, while all other lines belong to 6s-6p transition. Most of the existing papers are devoted to Stark width measurements and only one paper deals with shift data of the lines studied herein. A low-pressure pulsed arc with 95% of helium and 5% of xenon was used as a plasma source. All measurements were performed under following plasma conditions: electron density (0.2-1.4)10{sup 23}m{sup -3} and electron temperature 18000-23000 K.

  16. Nuclear field shift effect as a possible cause of Te isotopic anomalies in the early solar system —An alternative explanation of Fehr et al. (2006 and 2009)

    NASA Astrophysics Data System (ADS)

    Moynier, F.; Fujii, T.; Albarède, F.

    2009-12-01

    We explore the possibility that Te isotopic anomalies measured in Ca-Al-rich inclusions (Fehr et al. 2009) and in leachates of carbonaceous chondrites (Fehr et al. 2006) may be due to mass-independent effects controlled by nuclear field shift rather than to nucleosynthetic processes. Fehr et al.’s spectrum of mass-independent anomalies of Te isotopes shows a smooth correlation with mass number and nuclear charge distribution. Ratios of even to odd isotopes, as the 125Te/126Te ratio used by these authors for normalization are particularly prone to nuclear field shift effects. We show that the alternative normalization of isotopic ratios to 130Te/126Te strongly reduces the trend of isotopic fractionation with mass number, leaving only 125Te as truly anomalous. For both normalizations (125Te/126Te and 130Te/126Te), Fehr et al.’s results fit the theory of Bigeleisen (1996), which suggests that the nuclear field shift effect can potentially account for the observed Te isotope abundances, as an alternative to nucleosynthetic processes. We propose that these mass-independent effects may be acquired during accretion of sulfides from the solar nebula.

  17. Radioactive halos and ion microprobe measurement of Pb isotope ratios

    NASA Technical Reports Server (NTRS)

    Gentry, R. V.

    1974-01-01

    This investigation was to obtain, if possible, the Pb isotope ratios of both lunar and meteoritic troilite grains by utilizing ion microprobe techniques. Such direct in situ measurement of Pb isotope ratios would eliminate contamination problems inherent in wet chemistry separation procedures, and conceivably determine whether lunar troilite grains were of meteoritic origin. For comparison purposes two samples of meteoritic troilite were selected (one from Canyon Diablo) for analysis along with two very small lunar troilite grains (approximately 50-100 microns). It was concluded that the ion microprobe as presently operating, does not permit the in situ measurement of Pb isotope ratios in lunar or meteoritic troilite. On the basis of these experiments no conclusions could be drawn as to the origin of the lunar troilite grains.

  18. Progress in high temperature speckle-shift strain measurement system

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.; Barranger, John P.

    1990-01-01

    A fast, easy to use speckle tracking system is under development for the speckle-shift strain measurement technique. Preliminary correlation tests on wire specimens show strong correlations of well-developed speckle patterns. Stable cross-correlations were obtained from a tungsten filament at 2480 C. An analysis of the optical system determines the minimum required sampling frequency of the speckle pattern to be 2.55 pixels per speckle.

  19. Determining Timing and Magnitude of Dietary Shifts in Black Guillemots (Cepphus grylle) Using Stable Isotope Analysis of Flight Feathers

    NASA Astrophysics Data System (ADS)

    Kleese, M. C.; Boswell, K. M.; Divoky, G.; Barton, M. B.

    2016-02-01

    Recent decreases in Artic summer sea and increases in SST have caused changes in the marine ecosystems associated with ice-covered waters. A four-decade study of Black Guillemots (Cepphus grylle) on Cooper Island near Point Barrow, AK has shown that nestling quality and survival is linked to proximity to sea ice and SST. In recent years when sea ice retreats from the foraging area and SST increases to >4°C during the nestling period, parent guillemots have switched from their preferred prey, Arctic cod (Boreogadus saida), to less desirable fourhorn sculpin (Myoxocephalus quadricornis). The guillemots' shift from a cryopelagic fish to a nearshore demersal is hard to monitor through direct observation and we suggest a new method to assess the timing and magnitude of this dietary shift using stable isotope analysis of nestling flight feathers. Flight feathers (primaries, secondaries and tail feathers) provide a linear record of material incorporated into the body of the chick from the start of feather growth to fledging, a period of approximately 30 days. Arctic cod and fourhorn sculpin have distinctive diets and are reliant on different basal resources and should produce distinct isotopic signatures in guillemot tissues. We extracted vane tissues from sections of 30 black guillemot feathers grown in a breeding season that experienced an observed prey shift, and conducted stable carbon and nitrogen isotope analyses to determine whether such analyses could be used to assess the dietary shift linked with loss of sea ice and increasing SST. Most seabird populations are not as easily accessible as the guillemots of Cooper Island and thus observations of dietary composition are difficult to obtain. Development of a technique using nestling feathers to examine timing and magnitude of seasonal shifts in prey would preclude the need for daily observations and have great utility for monitoring the ecological effects of the continuing annual decrease in Arctic summer ice.

  20. Lamb-shift and electric field measurements in plasmas

    NASA Astrophysics Data System (ADS)

    Doveil, F.; Chérigier-Kovacic, L.; Ström, P.

    2017-01-01

    The electric field is a quantity of particular relevance in plasma physics. Indeed, its fluctuations are responsible for different macroscopic phenomena such as anomalous transport in fusion plasmas. Answering a long-standing challenge, we offer a new method to locally and non-intrusively measure weak electric fields and their fluctuations in plasmas, by means of a beam of hydrogen ions or atoms. We present measurements of the electric field in vacuum and in a plasma where Debye shielding is measured. For the first time, we have used the Lamb-shift resonance to measure oscillating electric fields around 1 GHz and observed the strong enhancement of the Lyman-α signal. The measurement is both direct and non-intrusive. This method provides sensitivity (mV cm-1) and temporal resolution (ns) that are three orders higher compared to current diagnostics. It thus allows measuring fluctuations of the electric field at scales not previously reached experimentally.

  1. Precise measurement of chromium isotopes by MC-ICPMS.

    PubMed

    Schiller, Martin; Van Kooten, Elishevah; Holst, Jesper C; Olsen, Mia B; Bizzarro, Martin

    2014-08-01

    We report novel analytical procedures allowing for the concurrent determination of the stable and mass-independent Cr isotopic composition of silicate materials by multiple collector inductively coupled mass spectrometry (MC-ICPMS). In particular, we focus on improved precision of the measurement of the neutron-rich isotope (54)Cr. Because nitride and oxide interferences are a major obstacle to precise and accurate (54)Cr measurements by MC-ICPMS, our approach is designed to minimize these interferences. Based on repeat measurements of standards, we show that the mass-independent (53)Cr and (54)Cr compositions can be routinely determined with an external reproducibility better than 2.5 and 5.8 ppm (2 sd), respectively. This represents at least a two-fold improvement compared to previous studies. Although this approach uses significantly more Cr (30-60 μg) than analysis by thermal ionization mass spectrometry (TIMS), our result indicate that it is possible to obtain an external reproducibility of 19 ppm for the μ(54)Cr when consuming amounts similar to that typically analyzed by TIMS (1 μg). In addition, the amount of time required for analysis by MC-ICPMS is much shorter thereby enabling a higher sample throughput. As a result of the improved analytical precision, we identified small apparent mass-independent differences between different synthetic Cr standards and bulk silicate Earth (BSE) when using the kinetic law for the mass bias correction. These differences are attributed to the Cr loss by equilibrium processes during production of the synthetic standards. The stable isotope data concurrently obtained have a precision of 0.05‰ Da (-1), which is comparable to earlier studies. Comparison of the measured isotopic composition of four meteorites with published data indicates that Cr isotope data measured by the technique described here are accurate to stated uncertainties. The stable Cr composition of the Bilanga and NWA 2999 achondrites suggests that the

  2. Precise measurement of chromium isotopes by MC-ICPMS

    PubMed Central

    Schiller, Martin; Van Kooten, Elishevah; Holst, Jesper C.; Olsen, Mia B.; Bizzarro, Martin

    2014-01-01

    We report novel analytical procedures allowing for the concurrent determination of the stable and mass-independent Cr isotopic composition of silicate materials by multiple collector inductively coupled mass spectrometry (MC-ICPMS). In particular, we focus on improved precision of the measurement of the neutron-rich isotope 54Cr. Because nitride and oxide interferences are a major obstacle to precise and accurate 54Cr measurements by MC-ICPMS, our approach is designed to minimize these interferences. Based on repeat measurements of standards, we show that the mass-independent 53Cr and 54Cr compositions can be routinely determined with an external reproducibility better than 2.5 and 5.8 ppm (2 sd), respectively. This represents at least a two-fold improvement compared to previous studies. Although this approach uses significantly more Cr (30–60 μg) than analysis by thermal ionization mass spectrometry (TIMS), our result indicate that it is possible to obtain an external reproducibility of 19 ppm for the μ54Cr when consuming amounts similar to that typically analyzed by TIMS (1 μg). In addition, the amount of time required for analysis by MC-ICPMS is much shorter thereby enabling a higher sample throughput. As a result of the improved analytical precision, we identified small apparent mass-independent differences between different synthetic Cr standards and bulk silicate Earth (BSE) when using the kinetic law for the mass bias correction. These differences are attributed to the Cr loss by equilibrium processes during production of the synthetic standards. The stable isotope data concurrently obtained have a precision of 0.05‰ Da −1, which is comparable to earlier studies. Comparison of the measured isotopic composition of four meteorites with published data indicates that Cr isotope data measured by the technique described here are accurate to stated uncertainties. The stable Cr composition of the Bilanga and NWA 2999 achondrites suggests that the

  3. Natural Ca Isotope Composition of Urine as a Rapid Measure of Bone Mineral Balance

    NASA Astrophysics Data System (ADS)

    Skulan, J.; Gordon, G. W.; Morgan, J.; Romaniello, S. J.; Smith, S. M.; Anbar, A. D.

    2011-12-01

    Naturally occurring stable Ca isotope variations in urine are emerging as a powerful tool to detect changes in bone mineral balance. Bone formation depletes soft tissue of light Ca isotopes while bone resorption releases isotopically light Ca into soft tissue. Previously published work found that variations in Ca isotope composition could be detected at 4 weeks of bed rest in a 90-day bed rest study (data collected at 4, 8 and 12 weeks). A new 30-day bed rest study involved 12 patients on a controlled diet, monitored for 7 days prior to bed rest and 7 days post bed rest. Samples of urine, blood and food were collected throughout the study. Four times daily blood samples and per void urine samples were collected to monitor diurnal or high frequency variations. An improved chemical purification protocol, followed by measurement using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) allowed accurate and precise determinations of mass-dependent Ca isotope variations in these biological samples to better than ±0.2% (δ44/42Ca) on <25 μg of Ca. Results from this new study show that Ca isotope ratios shift in a direction consistent with net bone loss after just 7 days, long before detectible changes in bone density by X-ray measurements occur. Consistent with this interpretation, the Ca isotope variations track changes observed in N-teleopeptide, a bone resorption biomarker. Bone-specific alkaline phosphatase, a bone formation biomarker, is unchanged over this period. Ca isotopes can in principle be used to quantify net changes in bone mass. Using a mass-balance model, our results indicate an average loss of 0.62 ± 0.16 % in bone mass over the course of this 30-day study. This is consistent with the rate of bone loss in longer-term studies as seen by X-ray measurements. This Ca isotope technique should accelerate the pace of discovery of new treatments for bone disease and provide novel insights into the dynamics of bone metabolism.

  4. Predictable oxygen isotope exchange of plant lipids improves our ability to understand hydrologic shifts and partition evapotranspiration across scales

    NASA Astrophysics Data System (ADS)

    Maxwell, T.; Silva, L. C. R.; Horwath, W. R.

    2016-12-01

    Understanding the partitioning of evapotranspiration is critical to assessing how changes in climate affect the terrestrial water cycle. N-alkyl lipids have been successfully used to integrate local to regional scale hydrologic change through the integration of δD measured in specific compounds found in sediments. However, such studies are limited compared to contemporary hydrologic studies which have the advantage of using dual isotope methods whereby δD and δ18O are used in conjunction to partition evapotranspiration. δD values in n-alkyl lipids have been established as resistant to exchange with environmental water and, this approach has allowed for routine measurement and reconstruction of plant water δD. In contrast, the use of δ18O in organic matter remains incipient because the low oxygen content of plant lipids makes it difficult to accurately measure δ18O. In the interest of addressing both fundamental and practical potential of a lipid δ18O proxy, we present the first evidence for predictable exchange of δ18O between environmental water and hydrophobic bulk organic matter, neutral saponified lipids, and specific plant derived compounds Our data suggests that these different pools may be used to reconstruct the original source water δD/δ18O relationship from soil or sedimentary organic matter, which will help elucidate hydrologic shifts in terrestrial systems. Our results bring new insight into methods by which organic compounds might be used to partition evapotranspiration across large spatial scales in both contemporary and reconstructed systems.

  5. Isotopic Measurements of Organic Sulfonates From The Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Chang, S.; DeVincenzi, Donald L. (Technical Monitor)

    1995-01-01

    Organic sulfonates and phosphonates have been extracted from the Murchison meteorite for stable isotope measurements. Preliminary stable isotope measurements of individual alkyl sulfonates, R-SO3H (R=C(sub n)H(sub 2n+l)), are shown. These compounds were found in aqueous extracts of Murchison. Both groups show trends similar to other homologous series of organic compounds indigenous to Murchison. Molecular abundances decrease with increasing carbon number, and all possible isomers at each carbon number (through C-4) are present. Carbon isotope measurements of the sulfonates show a decrease in the C-13/C-12 ratio with increasing carbon number. The overall objectives of this project are to obtain dime element carbon, hydrogen, and sulfur - intramolecular isotopic analyses of individual sulfonates, and isotopic measurement of carbon and hydrogen of the phosphonates as a group. The Murchison meteorite is the best characterized carbonaceous chondrite with respect to organic chemistry. The finding of organic sulfonates and phosphonates in Murchison is of interest because they are the first well-characterized series of sulfur and phosphorus containing organic compounds found in meteorites. Also, meteorites, comets, and interplanetary dust particles may have been involved in chemical evolution on the early Earth. Because of the critical role of organic phosphorus and sulfur in all living systems, it is particularly interesting to see examples of abiotic syntheses of these classes of compounds. The study of the isotopic composition of the sulfonates and phosphonates can yield insight into their possible interstellar origin as well as their mechanisms of synthesis in the early solar system. Previous isotopic analyses of other classes of organic compounds indigenous to meteorites, e.g., amino acids, carboxylic acids, and hydrocarbons indicate the possibility that interstellar molecules were incorporated into meteorite parent bodies. In these compounds the ratios of heavy to

  6. Isotopic Measurements of Organic Sulfonates From The Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Chang, S.; DeVincenzi, Donald L. (Technical Monitor)

    1995-01-01

    Organic sulfonates and phosphonates have been extracted from the Murchison meteorite for stable isotope measurements. Preliminary stable isotope measurements of individual alkyl sulfonates, R-SO3H (R=C(sub n)H(sub 2n+l)), are shown. These compounds were found in aqueous extracts of Murchison. Both groups show trends similar to other homologous series of organic compounds indigenous to Murchison. Molecular abundances decrease with increasing carbon number, and all possible isomers at each carbon number (through C-4) are present. Carbon isotope measurements of the sulfonates show a decrease in the C-13/C-12 ratio with increasing carbon number. The overall objectives of this project are to obtain dime element carbon, hydrogen, and sulfur - intramolecular isotopic analyses of individual sulfonates, and isotopic measurement of carbon and hydrogen of the phosphonates as a group. The Murchison meteorite is the best characterized carbonaceous chondrite with respect to organic chemistry. The finding of organic sulfonates and phosphonates in Murchison is of interest because they are the first well-characterized series of sulfur and phosphorus containing organic compounds found in meteorites. Also, meteorites, comets, and interplanetary dust particles may have been involved in chemical evolution on the early Earth. Because of the critical role of organic phosphorus and sulfur in all living systems, it is particularly interesting to see examples of abiotic syntheses of these classes of compounds. The study of the isotopic composition of the sulfonates and phosphonates can yield insight into their possible interstellar origin as well as their mechanisms of synthesis in the early solar system. Previous isotopic analyses of other classes of organic compounds indigenous to meteorites, e.g., amino acids, carboxylic acids, and hydrocarbons indicate the possibility that interstellar molecules were incorporated into meteorite parent bodies. In these compounds the ratios of heavy to

  7. Implications of utilization shifts on medical-care price measurement.

    PubMed

    Dunn, Abe; Liebman, Eli; Shapiro, Adam Hale

    2015-05-01

    The medical-care sector often experiences changes in medical protocols and technologies that cause shifts in treatments. However, the commonly used medical-care price indexes reported by the Bureau of Labor Statistics hold the mix of medical services fixed. In contrast, episode expenditure indexes, advocated by many health economists, track the full cost of disease treatment, even as treatments shift across service categories (e.g., inpatient to outpatient hospital). In our data, we find that these two conceptually different measures of price growth show similar aggregate rates of inflation over the 2003-2007 period. Although aggregate trends are similar, we observe differences when looking at specific disease categories. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Two-Color Laser Speckle Shift Strain Measurement System

    NASA Technical Reports Server (NTRS)

    Tuma, Margaret L.; Krasowski, Michael J.; Oberle, Lawrence G.; Greer, Lawrence C., III; Spina, Daniel; Barranger, John

    1996-01-01

    A two color laser speckle shift strain measurement system based on the technique of Yamaguchi was designed. The dual wavelength light output from an Argon Ion laser was coupled into two separate single-mode optical fibers (patchcords). The output of the patchcords is incident on the test specimen (here a structural fiber). Strain on the fiber, in one direction, is produced using an Instron 4502. Shifting interference patterns or speckle patterns will be detected at real-time rates using 2 CCD cameras with image processing performed by a hardware correlator. Strain detected in fibers with diameters from 21 microns to 143 microns is expected to be resolved to 15 mu epsilon. This system was designed to be compact and robust and does not require surface preparation of the structural fibers.

  9. Using Doppler Shifts of GPS Signals To Measure Angular Speed

    NASA Technical Reports Server (NTRS)

    Campbell, Charles E., Jr.

    2006-01-01

    A method has been proposed for extracting information on the rate of rotation of an aircraft, spacecraft, or other body from differential Doppler shifts of Global Positioning System (GPS) signals received by antennas mounted on the body. In principle, the method should be capable of yielding low-noise estimates of rates of rotation. The method could eliminate the need for gyroscopes to measure rates of rotation. The method is based on the fact that for a given signal of frequency ft transmitted by a given GPS satellite, the differential Doppler shift is attributable to the difference between those components of the instantaneous translational velocities of the antennas that lie along the line of sight from the antennas to the GPS satellite.

  10. Spatial-heterodyne interferometry for transmission (SHIFT) measurements

    DOEpatents

    Bingham, Philip R.; Hanson, Gregory R.; Tobin, Ken W.

    2006-10-10

    Systems and methods are described for spatial-heterodyne interferometry for transmission (SHIFT) measurements. A method includes digitally recording a spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis using a reference beam, and an object beam that is transmitted through an object that is at least partially translucent; Fourier analyzing the digitally recorded spatially-heterodyned hologram, by shifting an original origin of the digitally recorded spatially-heterodyned hologram to sit on top of a spatial-heterodyne carrier frequency defined by an angle between the reference beam and the object beam, to define an analyzed image; digitally filtering the analyzed image to cut off signals around the original origin to define a result; and performing an inverse Fourier transform on the result.

  11. Nonlinearity of Argon Isotope Measurements for Samples of Different Sizes

    NASA Astrophysics Data System (ADS)

    Cox, S. E.; Hemming, S. R.; Turrin, B. D.; Swisher, C. C.

    2010-12-01

    Uncertainty in isotope ratio linearity is not propagated into the final uncertainty of high-precision Ar-Ar analyses. Nonlinearity is assumed to be negligible compared to other sources of error, so mass discrimination is calculated using air pipettes of a single size similar to typical unknowns. The calculated discrimination factor is applied to all measured isotopes regardless of the difference in relative isotope abundance or the difference in gas pressure between the sample and the air pipette. We measured 40Ar/36Ar ratios of different size air samples created using up to twenty pipette shots on two different mass spectrometers with automated air pipette systems (a VG5400 and an MAP 215-50) in order to test the assumption that the measured isotope ratios are consistent at different gas pressures. We typically obtain reproducibility < 0.5% on the 40Ar/36Ar of similar size air standards, but we measured 40Ar/36Ar ratios for aliquots 0.5 to 20 times the typical volume from the same reservoir that varied by as much as 10% (Figure 1). In sets VG1, VG2, and MAP, 40Ar/36Ar ratios increased with gas pressure (expressed as number of air pipette shots; R2 > 0.9). Several months later, we performed the same measurements on the VG5400 with a new filament and different tuning parameters and obtained a different result (Set VG3). In this case, the 40Ar/36Ar ratios still varied with gas pressure, but less drastically (R2 > 0.3), and the slope was reversed--40Ar/36Ar ratios decreased with gas pressure. We conclude that isotope ratio nonlinearity is a common phenomenon that has the potential to affect monitor standard and timescale age calculations at the 0.1% level of significance defined by EARTHTIME. We propose that argon labs incorporate air pipettes of varying size and isotopic compositions to allow for routine calibration of isotope ratio nonlinearity in the course of high-precision analyses. Figure 1: Measured 40Ar/36Ar vs. number of air pipettes. Sets VG1, VG2, and MAP

  12. Phame: phase measurements on 45nm node phase shift features

    NASA Astrophysics Data System (ADS)

    Buttgereit, Ute; Birkner, Robert; Seidel, Dirk; Perlitz, Sascha; Philipsen, Vicky; De Bisschop, Peter

    2008-05-01

    The extension of optical lithography to the 45nm node and beyond goes along with increased mask complexity and tightening of specifications. The proper use of PSM becomes more and more important and the phase shift needs to be quantified exactly in order to achieve accurate CD printing results during wafer processing. The methods currently available run into limitations because they are not able to consider diffraction limitations caused by scanner NA and mask pitch, as well as 3D mask effects. In the transition to the 45nm node and beyond, these effects play an important role and need to be considered. Zeiss' new phase metrology system Phame® captures diffraction limitations, rigorous effects (i.e., a failure of the Kirchhoff approximation), and polarization effects. The new phase metrology system measures the phase shift in any in-die feature of the active mask area for on- and off-axis applications with high spatial resolution. This paper is focused on through pitch and through duty cycle measurements on an alternating PSM. Phame® measurements will be compared to AFM measurements. Additionally rigorous 3D simulations have been performed for different CD, varying pitch and varying duty cycle using coherent illumination with polarization. The simulation results will be compared to Phame® measurement results.

  13. Lifetime measurement of neutron-rich even-even molybdenum isotopes

    NASA Astrophysics Data System (ADS)

    Ralet, D.; Pietri, S.; Rodríguez, T.; Alaqeel, M.; Alexander, T.; Alkhomashi, N.; Ameil, F.; Arici, T.; Ataç, A.; Avigo, R.; Bäck, T.; Bazzacco, D.; Birkenbach, B.; Boutachkov, P.; Bruyneel, B.; Bruce, A. M.; Camera, F.; Cederwall, B.; Ceruti, S.; Clément, E.; Cortés, M. L.; Curien, D.; De Angelis, G.; Désesquelles, P.; Dewald, M.; Didierjean, F.; Domingo-Pardo, C.; Doncel, M.; Duchêne, G.; Eberth, J.; Gadea, A.; Gerl, J.; Ghazi Moradi, F.; Geissel, H.; Goigoux, T.; Goel, N.; Golubev, P.; González, V.; Górska, M.; Gottardo, A.; Gregor, E.; Guastalla, G.; Givechev, A.; Habermann, T.; Hackstein, M.; Harkness-Brennan, L.; Henning, G.; Hess, H.; Hüyük, T.; Jolie, J.; Judson, D. S.; Jungclaus, A.; Knoebel, R.; Kojouharov, I.; Korichi, A.; Korten, W.; Kurz, N.; Labiche, M.; Lalović, N.; Louchart-Henning, C.; Mengoni, D.; Merchán, E.; Million, B.; Morales, A. I.; Napoli, D.; Naqvi, F.; Nyberg, J.; Pietralla, N.; Podolyák, Zs.; Pullia, A.; Prochazka, A.; Quintana, B.; Rainovski, G.; Reese, M.; Recchia, F.; Reiter, P.; Rudolph, D.; Salsac, M. D.; Sanchis, E.; Sarmiento, L. G.; Schaffner, H.; Scheidenberger, C.; Sengele, L.; Singh, B. S. Nara; Singh, P. P.; Stahl, C.; Stezowski, O.; Thoele, P.; Valiente Dobon, J. J.; Weick, H.; Wendt, A.; Wieland, O.; Winfield, J. S.; Wollersheim, H. J.; Zielinska, M.; PreSPEC Collaboration

    2017-03-01

    Background: In the neutron-rich A ≈100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A =100 up to mass A =108 , and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the γ ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a γ -ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A =100 to A =108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: τ =29 .7-9.1+11.3 ps for the 4+ state of 108Mo and τ =3 .2-0.7+0.7 ps for the 6+ state of 102Mo. Conclusions: The reduced transition strengths B (E 2 ) , calculated from lifetimes measured in this experiment, compared to beyond

  14. [Thermometry by measuring the chemical shift of lanthanide complex].

    PubMed

    Konstanczak, P; Wust, P; Sander, B; Schründer, S; Frenzel, T; Wlodarczyk, W; Vogl, T; Müller, G; Felix, R

    1997-02-01

    In the long-term, non-invasive thermometry is vital for the continued clinical and technological development of regional hyperthermia. In magnetic resonance tomography. T1 relaxation time, diffusion and proton resonance frequency are used to measure temperature distributions. When used clinically in the pelvic region, all of these methods are plagued with errors and artefacts on account of the tissue relationships, tissue changes under hyperthermia, physiological and stochastic movements, inhomogeneities, drift phenomena and instabilities. We tested the relationship between the temperature and the chemical shift of a methyl group of a lanthanide complex with central atom praseodymium (Pr-MOE-DO3A. Schering AG). To do this we used cylindrical phantoms containing a 5-mmol-solution of this temperature-sensitive substance. High resolution spectra and relaxation times were determined in a Bruker AMX at 11.5 T. A calibration curve was then recorded by a Siemens Magnetom SP63 at 1.5 T. Local temperature distributions were determined using the chemical shift imaging method, with a matrix size of 16 x 8 and a narrow-band excitation pulse. The temperature distribution was created using a Nd:YAG laser applicator. At a distance of -25.7 ppm from the water line, we found a singlet line with a temperature-dependent chemical shift of 0.13 ppm/C. In the phantom experiment we found that the chemical shift had a linear relationship with a gradient independent of the surroundings, and a temperature resolution of +/-0.6 degree C. With a concentration of 1 mmol/l, a matrix size of 8 x 8 and a measurement period of 5 s per acquisition, phantom measurements using the CSI method produced a signal to noise ratio of 3.5 per acquisition, i.e a measurement period of 10 to 20 s per spectrum. Our in vitro data show that spectroscopic temperature measurement using a temperature-sensitive praseodymium complex with a therapeutically practical concentration of 1 mmol/l already appears to be

  15. Vadose Zone Infiltration Rates from Sr isotope Measurements

    NASA Astrophysics Data System (ADS)

    Maher, K.; Maher, K.; DePaolo, D. J.; DePaolo, D. J.; Conrad, M.

    2001-12-01

    Predicting infiltration rates and recharge through the vadose zone in arid regions is difficult and hence developing methods for the measurement of infiltration rates is important. We have been investigating the use of Sr isotope measurements for determining infiltration at the 200 Area plateau on the Hanford reservation in central Washington. In this context, infiltration affects the transport of contaminants to the water table as well as recharge of the groundwater system. Using Sr isotopes for this purpose requires drill core and water samples from the vadose zone, although leaches of the cores can substitute for water samples. Complementary information, including some constraints on regional recharge, can also be obtained using water samples from groundwater monitoring wells. The VZ method is based on the fact that the Sr isotope ratio of soil water just below the surface is often set by dissolution of aeolian material including carbonate, and this ratio is different from the average value in the deeper underlying vadose zone rock matrix. As water infiltrates, the Sr isotopic composition of the water changes toward the rock values as a result of Sr released from the rocks by weathering reactions. The rate of change with depth of the Sr isotope ratio of the vadose zone water is a function ultimately of q/R; the ratio of the infiltration flux (q) to the bulk rock weathering rate (R). Where it is possible to evaluate R, q can be estimated. As data accumulate it may be possible to improve the calibration of the method. At Hanford the vadose zone rock material is mostly unconsolidated sand, silt, and gravel of broadly granitic composition, which constitute the Hanford and Ringold formations. Annual precipitation is about 160 mm/yr. Drilling and coring of a ca. 70m hole to the water table in 1999 as part of the Hanford groundwater monitoring program, in a relatively undisturbed area of the site, allowed us to generate a unique Sr isotope data set. The Sr isotope

  16. Alternative Approaches to Uncertainty Calculations for TIMS Isotopic Measurements

    NASA Astrophysics Data System (ADS)

    Thomas, R. B.; Essex, R. M.; Goldberg, S. A.

    2006-12-01

    Two methods of estimating uncertainty for TIMS U isotopic ratio measurements were evaluated. Although these methods represent fundamentally different approaches both are consistent with the principles outlined in the ISO "Guide to the Expression of Uncertainty in Measurements" (GUM). In the "Discrete Component" approach all of the identifiable sources of random variability associated with the mass spectrometer (gain variability, baseline variability, cup efficiency variability, Schottky noise, counting statistics) are individually assessed to estimate measurement reproducibility. The second approach is an "Integrated" method, which uses observed reproducibility of repeated identical sample measurements to confound the various components of random variability. Evaluation of the uncertainty budgets for the two methods shows that the relative importance of an uncertainty component in a measurement is highly dependent on the measurement technique and the isotopic ratio of the measured value. For example, the uncertainty of the ^{235}U/^{238}U ratio of the material analyzed in this study will generally be dominated by the uncertainty of the CRM used to determine the mass fractionation factor. The more extreme 234U/^{238}U and ^{236}U/^{238}U ratios are often dominated by other factors such as internal and external reproducibility. Although both methods are consistent with the GUM principles, there are many instrumental factors that can produce measurement variability but are not readily quantifiable (i.e., small differences in run conditions, filament geometry, sample loading, etc). Accordingly, the Discrete Component determination can accurately estimate internal reproducibility of an isotopic measurement but will not sufficiently characterize analysis-to- analysis variability that is inherent in all measurements. The Integrated approach to uncertainty evaluation has the advantage of not requiring the quantification of an extensive set of variables and also greatly

  17. Accurate and precise zinc isotope ratio measurements in urban aerosols.

    PubMed

    Gioia, Simone; Weiss, Dominik; Coles, Barry; Arnold, Tim; Babinski, Marly

    2008-12-15

    We developed an analytical method and constrained procedural boundary conditions that enable accurate and precise Zn isotope ratio measurements in urban aerosols. We also demonstrate the potential of this new isotope system for air pollutant source tracing. The procedural blank is around 5 ng and significantly lower than published methods due to a tailored ion chromatographic separation. Accurate mass bias correction using external correction with Cu is limited to Zn sample content of approximately 50 ng due to the combined effect of blank contribution of Cu and Zn from the ion exchange procedure and the need to maintain a Cu/Zn ratio of approximately 1. Mass bias is corrected for by applying the common analyte internal standardization method approach. Comparison with other mass bias correction methods demonstrates the accuracy of the method. The average precision of delta(66)Zn determinations in aerosols is around 0.05 per thousand per atomic mass unit. The method was tested on aerosols collected in Sao Paulo City, Brazil. The measurements reveal significant variations in delta(66)Zn(Imperial) ranging between -0.96 and -0.37 per thousand in coarse and between -1.04 and 0.02 per thousand in fine particular matter. This variability suggests that Zn isotopic compositions distinguish atmospheric sources. The isotopic light signature suggests traffic as the main source. We present further delta(66)Zn(Imperial) data for the standard reference material NIST SRM 2783 (delta(66)Zn(Imperial) = 0.26 +/- 0.10 per thousand).

  18. Stable isotope measurements of evapotranspiration partitioning in a maize field

    NASA Astrophysics Data System (ADS)

    Hogan, Patrick; Parajka, Juraj; Oismüller, Markus; Strauss, Peter; Heng, Lee; Blöschl, Günter

    2017-04-01

    Evapotranspiration (ET) is one of the most important processes in describing land surface - atmosphere interactions as it connects the energy and water balances. Furthermore knowledge of the individual components of evapotranspiration is important for ecohydrological modelling and agriculture, particularly for irrigation efficiency and crop productivity. In this study, we tested the application of the stable isotope method for evapotranspiration partitioning to a maize crop during the vegetative stage, using sap flow sensors as a comparison technique. Field scale ET was measured using an eddy covariance device and then partitioned using high frequency in-situ measurements of the isotopic signal of the canopy water vapor. The fraction of transpiration (Ft) calculated with the stable isotope method showed good agreement with the sap flow method. High correlation coefficient values were found between the two techniques, indicating the stable isotope method can successfully be applied in maize. The results show the changes in transpiration as a fraction of evapotranspiration after rain events and during the subsequent drying conditions as well as the relationship between transpiration and solar radiation and vapor pressure deficit.

  19. Characterising ontogenetic niche shifts in Nile crocodile using stable isotope (δ13C, δ15N) analyses of scute keratin.

    PubMed

    Radloff, Frans G T; Hobson, Keith A; Leslie, Alison J

    2012-09-01

    Nile crocodiles undergo a three to five order of magnitude increase in body size during their lifespan. This shift coincides with a change in resource and habitat use which influences the strength, type and symmetry of interactions with other species. Identifying size-specific crocodile groups displaying similar traits is important for conservation planning. Here, we illustrate how stable carbon (δ(13) C) and nitrogen (δ(15) N) isotope analysis of scute keratin, together with breakpoint modelling analysis can be used to characterise ontogenetic niche shifts. Using a sample set of 238 crocodiles from the Okavango Delta, Botswana (35-463 cm total length), we found prominent size-related changes in the scute keratin δ(13) C and δ(15) N profiles close to 40 and 119 cm snout-vent length. The first shift corroborated the findings of a traditional stomach-content study conducted on the same population at the same time, and the second conformed to known crocodile ecology. This approach can be used as a first approximation to identify size-specific groups within crocodile populations, and these can then be investigated further using isotopic or other methods.

  20. Dietary shift after 3600 cal yr BP and its influencing factors in northwestern China: Evidence from stable isotopes

    NASA Astrophysics Data System (ADS)

    Ma, Minmin; Dong, Guanghui; Jia, Xin; Wang, Hui; Cui, Yifu; Chen, Fahu

    2017-04-01

    :Human diets rely on natural resource availability and can reflect social and cultural values. When environments, societies, and cultures change, diets may also shift. This study traced the extent of dietary change and the factors influencing such change. Through stable carbon and nitrogen isotopic analysis of late Neolithic and early Bronze Age human and animal bone collagen, we found that significant shifts in human diets were closely associated with intercontinental cultural exchanges in Eurasia and climate change in northwestern China. The isotopic evidence indicated that human diets mainly consisted of C4 foodstuffs (presumably millet and/or animals fed with C4 foods) around 4000 calibrated years before the present (cal yr BP), corresponding to the flourishing of millet agriculture in the context of the optimal climate conditions of the mid-Holocene. Subsequently, more C3 foods (probably wheat, barley, and animals fed with C3 foods) were added to human diets post-3600 cal yr BP when the climate became cooler and drier. Such dietary variation is also consistent with the increasing intensity of long-distance exchange after 4000 cal yr BP. While many factors can lead to human dietary shifts (e.g. climate change, population growth, cultural factors, and human migration), climate may have been a key factor in Gansu and Qinghai.

  1. Dietary shift after 3600 cal yr BP and its influencing factors in northwestern China: Evidence from stable isotopes

    NASA Astrophysics Data System (ADS)

    Ma, Minmin; Dong, Guanghui; Jia, Xin; Wang, Hui; Cui, Yifu; Chen, Fahu

    2016-08-01

    Human diets rely on natural resource availability and can reflect social and cultural values. When environments, societies, and cultures change, diets may also shift. This study traced the extent of dietary change and the factors influencing such change. Through stable carbon and nitrogen isotopic analysis of late Neolithic and early Bronze Age human and animal bone collagen, we found that significant shifts in human diets were closely associated with intercontinental cultural exchanges in Eurasia and climate change in northwestern China. The isotopic evidence indicated that human diets mainly consisted of C4 foodstuffs (presumably millet and/or animals fed with C4 foods) around 4000 calibrated years before the present (cal yr BP), corresponding to the flourishing of millet agriculture in the context of the optimal climate conditions of the mid-Holocene. Subsequently, more C3 foods (probably wheat, barley, and animals fed with C3 foods) were added to human diets post-3600 cal yr BP when the climate became cooler and drier. Such dietary variation is also consistent with the increasing intensity of long-distance exchange after 4000 cal yr BP. While many factors can lead to human dietary shifts (e.g. climate change, population growth, cultural factors, and human migration), climate may have been a key factor in Gansu and Qinghai.

  2. Stable Isotopes in Pocket Gopher Teeth as Evidence of a Late Matuyama Climate Shift in the Southern Rocky Mountains

    NASA Astrophysics Data System (ADS)

    Rogers, Karel L.; Wang, Yang

    2002-03-01

    Previous work in the San Luis Valley of south-central Colorado and northern New Mexico at the Hansen Bluff and SAM Cave localities has allowed reconstruction of the paleoclimate in the region during the interval from ∼0.6 myr to ∼2.6 myr. Surface exposures at Hansen Bluff have been correlated to deep-sea oxygen isotope core stages 18-23 and one of the glacial periods contained therein to the oldest "Nebraskan" till in southwestern Iowa. Deposits in SAM Cave correlate to Hansen Bluff on the basis of paleomagnetics, climate interpretation, and microtine rodent biochronology. In this paper, carbon and oxygen stable isotope data of herbivorous rodent teeth are used as indicators of change in the predominance of C3, C4, and CAM plants and of changes in temperature and precipitation. Taken together with other previously analyzed data from these localities, the evidence indicates a shift in the severity of glacial events that is mainly related to the hydrologic characteristics of the climate. This shift may have been caused by broad regional uplift that may have been instrumental in shifting global climate cycles from the 41,000-yr Matuyama cycles to the Brunhes 100,000-yr-dominated cycles.

  3. Lifetime measurements in neutron-rich 63,65Co isotopes using the AGATA demonstrator

    NASA Astrophysics Data System (ADS)

    Modamio, V.; Valiente-Dobón, J. J.; Lunardi, S.; Lenzi, S. M.; Gadea, A.; Mengoni, D.; Bazzacco, D.; Algora, A.; Bednarczyk, P.; Benzoni, G.; Birkenbach, B.; Bracco, A.; Bruyneel, B.; Bürger, A.; Chavas, J.; Corradi, L.; Crespi, F. C. L.; de Angelis, G.; Désesquelles, P.; de France, G.; Depalo, R.; Dewald, A.; Doncel, M.; Erduran, M. N.; Farnea, E.; Fioretto, E.; Fransen, Ch.; Geibel, K.; Gottardo, A.; Görgen, A.; Habermann, T.; Hackstein, M.; Hess, H.; Hüyük, T.; John, P. R.; Jolie, J.; Judson, D.; Jungclaus, A.; Karkour, N.; Kempley, R.; Leoni, S.; Melon, B.; Menegazzo, R.; Michelagnoli, C.; Mijatović, T.; Million, B.; Möller, O.; Montagnoli, G.; Montanari, D.; Nannini, A.; Napoli, D. R.; Podolyak, Zs.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Rother, W.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Sieja, K.; Söderström, P. A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Travers, B.; Ur, C. A.

    2013-10-01

    Lifetimes of the low-lying (11/2-) states in 63,65Co have been measured employing the recoil distance doppler shift method (RDDS) with the AGATA γ-ray array and the PRISMA mass spectrometer. These nuclei were populated via a multinucleon transfer reaction by bombarding a 238U target with a beam of 64Ni. The experimental B(E2) reduced transition probabilities for 63,65Co are well reproduced by large-scale shell-model calculations that predict a constant trend of the B(E2) values up to the N=40 67Co isotope.

  4. Towards a Lamb shift measurement in muonic hydrogen

    NASA Astrophysics Data System (ADS)

    Kottmann, F.; Biraben, F.; Conde, C. A. N.; Donche-Gay, C.; Hänsch, T. W.; Hartmann, F. J.; Hauser, P.; Hughes, V. W.; Huot, O.; Indelicato, P.; Knowles, P.; Liu, Y.-W.; Markushin, V. E.; Mulhauser, F.; Nez, F.; Pohl, R.; Rabinowitz, P.; dos Santos, J. M. F.; Schaller, L. A.; Schneuwly, H.; Schott, W.; Taqqu, D.; Veloso, J. F. C. A.

    2001-04-01

    A measurement of the 2S Lamb shift (2S-2P energy difference) in muonic hydrogen (μ-p) is being prepared at the Paul Scherrer Institute (PSI). The goal of the experiment is to measure the Lamb shift with 30 ppm precision and to deduce the root mean square (rms) proton charge radius with 10-3 relative accuracy, 20 times more precise than presently known. The experiment is based on the availability of long-lived metastable muonic hydrogen atoms in the 2S state which has been investigated in a recent series of experiments at PSI. From the low-energy part of the initial kinetic energy distribution of μp(2S) atoms we determined the fraction of long-lived μp(2S) to be ˜1.5% for H2 gas pressures between 1 and 64 hPa. Another analysis involving μp(1S) with a kinetic energy of 0.9 keV originating from quenching of thermalized μp(2S) via the resonant process μp(2S)+H2→{[(ppμ)+]*pee}*→μp(1S)+p+…+2 keV gives the same result. This is the first direct observation of long-lived μp(2S) atoms. The realization of the μp Lamb shift experiment involves a new low-energy negative muon beam with entrance detectors for keV-muons, a xenon gas-proportional-scintillation-chamber (GPSC) read out by a microstrip-gas-chamber (MSGC) for the detection of 2 keV X-rays, and a randomly triggered 3-stage laser system providing 0.5 mJ, 7 ns laser pulses at 6.02 μm wavelength.

  5. Human-Induced Long-Term Shifts in Gull Diet from Marine to Terrestrial Sources in North America's Coastal Pacific: More Evidence from More Isotopes (δ2H, δ34S).

    PubMed

    Hobson, Keith A; Blight, Louise K; Arcese, Peter

    2015-09-15

    Measurements of naturally occurring stable isotopes in tissues of seabirds and their prey are a powerful tool for investigating long-term changes in marine foodwebs. Recent isotopic (δ(15)N, δ(13)C) evidence from feathers of Glaucous-winged Gulls (Larus glaucescens) has shown that over the last 150 years, this species shifted from a midtrophic marine diet to one including lower trophic marine prey and/or more terrestrial or freshwater foods. However, long-term isotopic patterns of δ(15)N and δ(13)C cannot distinguish between the relative importance of lower trophic-level marine foods and terrestrial sources. We examined 48 feather stable-hydrogen (δ(2)H) and -sulfur (δ(34)S) isotope values from this same 150-year feather set and found additional isotopic evidence supporting the hypothesis that gulls shifted to terrestrial and/or freshwater prey. Mean feather δ(2)H and δ(34)S values (± SD) declined from the earliest period (1860-1915; n = 12) from -2.5 ± 21.4 ‰ and 18.9 ± 2.7 ‰, respectively, to -35.5 ± 15.5 ‰ and 14.8 ± 2.4 ‰, respectively, for the period 1980-2009 (n = 12). We estimated a shift of ∼ 30% increase in dependence on terrestrial/freshwater sources. These results are consistent with the hypothesis that gulls increased terrestrial food inputs in response to declining forage fish availability.

  6. Study of muonic atoms in the A = 40 to 70 and A = 100 to 130 mass regions (nuclear charge radii, isotope and isotone shifts) and in the Sm-Gd and W-Os-Pt transition regions (electric monopole and quadrupole moments). Progress report No. 5, December 1, 1979-October 15, 1980. [Dept. of Physics, Purdue Univ. , 12/1/79-10/15/80

    SciTech Connect

    Steffen, R M

    1980-10-01

    The muonic x-ray spectra of the stable Ru and Pd isotope have been measured, and the data have been analyzed in terms of the effective Barrett radii and in terms of isotope shifts. The effects of the neutron subshell closure on the ..delta..N = 2 isotopes shifts at N = 56 is much smaller in the Ru (Z = 44) isotopes as compared to the recently observed effect in the Mo (Z = 42) isotope shifts. This is the first time a pronounced difference in ..delta..N = 2 isotope shifts has been observed for different values of Z. The muonic x-ray measurements on 24 stable isotopes of Cd, Sn, Te, and Ba have been completed and the analysis of the 74 spectra (including calibration spectra) is progressing. The work on the quadrupole parameters of the even-A Os nuclei has been completed. The analysis of the muonic x-ray spectra of the even-A Gd isotopes is near completion. Monopole and quadrupole charge parameters of the 0/sub g//sup +/ and 2/sub g//sup +/ states (and in the case of /sup 160/Gd, of the 3/sup -/ state) have been determined. The model dependence of extracting point-quadrupole matrix elements from muonic x-ray measurements has been carefully investigated. It was found that neither the ..beta..-vibration nor the ..gamma..-vibration modes influence the value of the extracted point moments by more than 2 percent. The problem of nuclear polarization corrections was examined.

  7. Divergence model for measurement of Goos-Hanchen shift

    NASA Astrophysics Data System (ADS)

    Gray, Jeffrey Frank

    In this effort a new measurement technique for the lateral Goos-Hanchen shift is developed, analyzed, and demonstrated. The new technique uses classical image formation methods fused with modern detection and analysis methods to achieve higher levels of sensitivity than obtained with prior practice. Central to the effort is a new mathematical model of the dispersion seen at a step shadow when the Goos-Hanchen effect occurs near critical angle for total internal reflection. Image processing techniques are applied to measure the intensity distribution transfer function of a new divergence model of the Goos-Hanchen phenomena providing verification of the model. This effort includes mathematical modeling techniques, analytical derivations of governing equations, numerical verification of models and sensitivities, optical design of apparatus, image processing. Keywords--Goos-Hanchen, total internal reflection, evanescent waves, image processing, Canny filters, sub-pixel, Superresolution.

  8. Isotope Shifts in the TiO B- X (1-0) Band

    NASA Astrophysics Data System (ADS)

    Amiot, C.; Luc, P.; Vetter, R.

    2002-08-01

    The absorption spectrum of the B3Π- X3Δ (1-0) band of the TiO molecule has been studied at sub-Doppler resolution by crossing an effusive beam of TiO with a cw tunable laser beam and by collecting the induced fluorescence light. The five bands involving the 46Ti, 47Ti, 48Ti, 49Ti, and 50Ti isotopic species have been observed and interpreted. A simultaneous analysis of the five isotopic data leads to accurate molecular constants and energy levels for the B3Π electronic state.

  9. Patient-centred measurement in ophthalmology – a paradigm shift

    PubMed Central

    Pesudovs, Konrad

    2006-01-01

    Ophthalmologists and researchers in ophthalmology understand what a rapidly evolving field ophthalmology is, and that to conduct good research it is essential to use the latest and best methods. In outcomes research, one modern initiative has been to conduct holistic measurement of outcomes inclusive of the patient's point of view; patient-centred outcome. This, of course, means including a questionnaire. However, the irony of trying to improve outcomes research by being inclusive of many measures is that the researcher may not be expert in all measures used. Certainly, few people conducting outcomes research in ophthalmology would claim to be questionnaire experts. Most tend to be experts in their ophthalmic subspecialty and probably simply choose a popular questionnaire that appears to fit their needs and think little more about it. Perhaps, unlike our own field, we assume that the field of questionnaire research is relatively stable. This is far from the case. The measurement of patient-centred outcomes with questionnaires is a rapidly evolving field. Indeed, over the last few years a paradigm shift has occurred in patient-centred measurement. PMID:16774690

  10. Measuring atmospheric visibility cavity attenuated phase shift spectroscopy

    NASA Astrophysics Data System (ADS)

    Jie, Guo; Ye, Shan-Shan; Yang, Xiao; Han, Ye-Xing; Tang, Huai-Wu; Yu, Zhi-Wei

    2016-10-01

    In the paper, an accurate and sensitive cavity attenuated phase shift spectroscopy (CAPS) system was used to monitor the atmospheric visibility coefficient in urban areas. The CAPS system, which detects the atmospheric visibility within a 10 nm bandpass centered at 532 nm, comprises a green LED with center wavelength in 532nm, a resonant optical cavity (36 cm length), a Photo Multiplier Tube detector and a lock in amplifier. The performance of the CAPS system was evaluated by measuring of the stability and response of the system. The minima ( 0.06 Mm-1) in the Allan plots show the optimum average time( 80s) for optimum detection performance of the CAPS system. The 2L/min flow rate, the CAPS system rise and fall response time is about 15 s, so as to realize the fast measurement of visibility. By comparing the forward scatter visibility meter measurement results, the CAPS system measurement results are verified reliably, and have high precision measurement. These figures indicate that this method has the potential to become one of the most sensitive on-line analytical techniques for atmospheric visibility detection.

  11. Thermocline Temperature Variability Reveals Shifts in the Tropical Pacific Mean State across Marine Isotope Stage 3

    NASA Astrophysics Data System (ADS)

    Hertzberg, J. E.; Schmidt, M. W.

    2014-12-01

    The eastern equatorial Pacific (EEP) is one of the most dynamic oceanographic regions, making it a critical area for understanding past climate change. Despite this, there remains uncertainty on the climatic evolution of the EEP through the last glacial period. According to the ocean dynamical thermostat theory, warming (cooling) of the tropical Pacific Ocean may lead to a more La Niña (El Niño)-like mean state due to zonally asymmetric heating and subsequent easterly (westerly) wind anomalies at the equator (Clement and Cane, 1999). Attempts to understand these feedbacks on millennial timescales across Marine Isotope Stage 3 (MIS 3) have proven to be fruitful in the western equatorial Pacific (WEP) (Stott et al., 2002), yet complimentary, high-resolution records from the EEP are lacking. To provide a more complete understanding of the feedback mechanisms of the dynamical thermostat across periods of abrupt climate change, we reconstruct thermocline temperature variability across MIS 3 from a sediment core located in the EEP, directly within the equatorial cold tongue upwelling region (core MV1014-02-17JC). Temperature anomalies in thermocline waters of the EEP are integrally linked to the ENSO system, with large positive and negative anomalies recorded during El Niño and La Niña events, respectively. Mg/Ca ratios in the thermocline-dwelling planktonic foraminifera Neogloboquadrina dutertrei were measured at 2 cm intervals, resulting in a temporal resolution of <200 years. Preliminary results across Interstadials 5-7 reveal warmer thermocline temperatures (an increase in Mg/Ca of .25 ± .02 mmol/mol) during periods of cooling following peak Interstadial warmth over Greenland, as seen from the NGRIP δ18O record. Thus, periods of cooling over Greenland appear to correspond to an El Niño-like mean state in the tropical Pacific, in line with predictions of an ocean dynamical thermostat. Interestingly, Heinrich Event 3 corresponds to cooler thermocline

  12. Pooled versus separate measurements of tree-ring stable isotopes.

    PubMed

    Dorado Liñán, Isabel; Gutiérrez, Emilia; Helle, Gerhard; Heinrich, Ingo; Andreu-Hayles, Laia; Planells, Octavi; Leuenberger, Markus; Bürger, Carmen; Schleser, Gerhard

    2011-05-01

    δ(13)C and δ(18)O of tree rings contain time integrated information about the environmental conditions weighted by seasonal growth dynamics and are well established as sources of palaeoclimatic and ecophysiological data. Annually resolved isotope chronologies are frequently produced by pooling dated growth rings from several trees prior to the isotopic analyses. This procedure has the advantage of saving time and resources, but precludes from defining the isotopic error or statistical uncertainty related to the inter-tree variability. Up to now only a few studies have compared isotope series from pooled tree rings with isotopic measurements from individual trees. We tested whether or not the δ(13)C and the δ(18)O chronologies derived from pooled and from individual tree rings display significant differences at two locations from the Iberian Peninsula to assess advantages and constraints of both methodologies. The comparisons along the period 1900-2003 reveal a good agreement between pooled chronologies and the two mean master series which were created by averaging raw individual values (Mean) or by generating a mass calibrated mean (MassC). In most of the cases, pooled chronologies show high synchronicity with averaged individual samples at interannual scale but some differences also show up especially when comparing δ(18)O decadal to multi-decadal variations. Moreover, differences in the first order autocorrelation among individuals may be obscured by pooling strategies. The lack of replication of pooled chronologies prevents detection of a bias due to a higher mass contribution of one sample but uncertainties associated with the analytical process itself, as sample inhomogeneity, seems to account for the observed differences.

  13. Measurement of isotopic abundances in collected stratospheric ozone samples

    SciTech Connect

    Schueler, B.; Morton, J.; Mauersberger, K. )

    1990-08-01

    Enrichment of heavy O{sub 3} isotopes has been measured in collected stratospheric samples. A balloon-borne cryogenic sampler was used to gather six O{sub 3} samples between 26 and 35 km in three flights. Subsequent laboratory mass spectrometer analysis of rare O{sub 3} isotopes at both mass 49 and 50 has resulted in more precise measurements than have previously been reported with in situ and ground-based techniques. In one flight, {sup 50}O{sub 3} was enriched by 12-16% and {sup 49}O{sub 3} by 9-11%, both increasing with altitude. In the remaining two flights, the isotope enrichment was nearly mass-independent at 8-9%. The enrichments in O{sub 3} at mass 50 are less than the large 40% value observed in some stratospheric measurements but similar to {sup 49}O{sub 3} and {sup 50}O{sub 3} fractionations produced in laboratory-generated ozone.

  14. Quantitative Measurement of the Doppler Shift at an Ultrasonic Frequency

    ERIC Educational Resources Information Center

    Nerbun, R. C.; Leskovec, R. A.

    1976-01-01

    Discussed is a Doppler shift laboratory experiment for an introductory college physics course. Ultrasonic transducers and a digital phase detector circuit "black box" are used to overcome room noise and "standing waves" and to produce an observable frequency shift. (SL)

  15. Quantitative Measurement of the Doppler Shift at an Ultrasonic Frequency

    ERIC Educational Resources Information Center

    Nerbun, R. C.; Leskovec, R. A.

    1976-01-01

    Discussed is a Doppler shift laboratory experiment for an introductory college physics course. Ultrasonic transducers and a digital phase detector circuit "black box" are used to overcome room noise and "standing waves" and to produce an observable frequency shift. (SL)

  16. Venous compliance and fluid shift measurements on Spacelab IML-1

    NASA Technical Reports Server (NTRS)

    Leiski, D.; Thirsk, R. B.; Charles, J. B.; Bennett, B.

    1992-01-01

    During the first few hours of a human spaceflight mission, a headward fluid shift out of the abdomen, pelvis, and legs initiates a number of adaptive cardiovascular responses, including a loss of intravascular and extravascular fluid volume. On return to earth, these cardiovascular changes may lead to debilitating symptoms of orthostatic intolerance in an unprotected astronaut. To test the hypothesis that an inflight increase in compliance of the leg veins may contribute to this condition, measurements of lower leg fluid shift and bulk venous compliance were collected from crew members during the eight-day First International Microgravity Laboratory shuttle mission. An ultrasonic limb plethysmograph, in conjunction with two compression cuffs encircling the calf and thigh, was used to determine bulk compliance of the underlying veins over a range of negative and positive transmural pressures. The data from inflight experiment sessions were compared to preflight and postflight sessions. The preliminary results indicate that the volume of the lower leg decreased by over 10 percent by the sixth day of flight, but there was no apparent change in venous compliance.

  17. Venous compliance and fluid shift measurements on Spacelab IML-1

    NASA Technical Reports Server (NTRS)

    Leiski, D.; Thirsk, R. B.; Charles, J. B.; Bennett, B.

    1992-01-01

    During the first few hours of a human spaceflight mission, a headward fluid shift out of the abdomen, pelvis, and legs initiates a number of adaptive cardiovascular responses, including a loss of intravascular and extravascular fluid volume. On return to earth, these cardiovascular changes may lead to debilitating symptoms of orthostatic intolerance in an unprotected astronaut. To test the hypothesis that an inflight increase in compliance of the leg veins may contribute to this condition, measurements of lower leg fluid shift and bulk venous compliance were collected from crew members during the eight-day First International Microgravity Laboratory shuttle mission. An ultrasonic limb plethysmograph, in conjunction with two compression cuffs encircling the calf and thigh, was used to determine bulk compliance of the underlying veins over a range of negative and positive transmural pressures. The data from inflight experiment sessions were compared to preflight and postflight sessions. The preliminary results indicate that the volume of the lower leg decreased by over 10 percent by the sixth day of flight, but there was no apparent change in venous compliance.

  18. Aragonite-Calcite Inversion During Biogenic Carbonate Sampling: Considerations for Interpreting Isotopic Measurements in Paleoclimate Studies

    NASA Astrophysics Data System (ADS)

    Waite, A. J.; Swart, P. K.

    2011-12-01

    As aragonite is the metastable polymorph of calcium carbonate, it lends itself to monotropic inversion to the more stable polymorph, calcite. This inversion is possible through an increase in the temperature and pressure conditions to which the sample is exposed and, although first noted nearly a century ago, has been primarily discussed in the context of sample roasting prior to analyses in paleoclimatological studies. Over the last several decades, however, researchers have found evidence to suggest that the friction associated with the sampling of biogenic carbonates via milling/drilling also induces inversion. Furthermore, this inversion may be associated with a shift in measured oxygen isotopic values and ultimately have significant implications for the interpretation of paleoclimatic reconstructions. Despite this, the isotopic heterogeneity of biogenic aragonite skeletons makes the effects of inversion challenging to test and the subject remains underrepresented in the literature. Here we present a first order study into the effects of milling on both the mineralogy and isotopic compositions measured in sclerosponges, corals, and molluscs. X-Ray diffraction analysis of samples hand ground with a mortar and pestle reveal 100% aragonitic skeletons. Conversely, samples milled with a computerized micromill show measurable inversion to calcite. On average, percent inversion of aragonite to calcite for individual specimens was 15% for sclerosponges, 16% for corals, and 9% for molluscs. Isotopic data from these specimens show that the higher the percentage of aragonite inverted to calcite, the more depleted the measured oxygen isotopic values. In the largest of the datasets (sclerosponges), it is evident that the range of oxygen isotope values from milled samples (-0.02 to +0.84%) exceeds the range in values for those samples which were hand ground and showed no inversion (+0.53 to +0.90%). This, coupled with the strong correlation between the two variables

  19. Normal mode analysis of isotopic shifts in Raman spectrum of TNT-d5

    NASA Astrophysics Data System (ADS)

    Liu, Yuemin; Tzeng, Nianfeng; Liu, Yucheng; Junk, Thomas

    2017-09-01

    A combined experimental-computational study was conducted on the Raman spectrum of TNT-d5 in the present study. It was found that among the 24 hybrid density functional theory (DFT) methods, O3LYP, tHCTHhyb, and B3LYP simulations yielded the strongest Raman bands which were closest to those measured from experiments. Simulations of hybrid DFT methods did not show that deuterium replacements alter orientations of 2- and 6-nitro with respect to phenyl ring, considering a larger size of the methyl group. However, the deuterium replacements apparently changed the reduced masses for all deuterium related vibrations. Although no difference of structural parameters was shown between TNT and its deuterated analogue, discrepancy was indicated in vibrational zero energy from our simulations. O3LYP simulation exhibited 24 deuterium involved vibrations, which were coupled into seven Raman bands of TNT-d5. This phenomenon can account for the experimental Raman band shifts or split of TNT-d5 when compared with the corresponding bands of TNT. The present study and its outcomes provide in-depth microchemical insights of Raman characteristics of TNT and may facilitate the design of nano-structures of SERS substrates for detection of TNT and its degradation products. All intensities displayed in this study were calculated from numerical simulations.

  20. Mass spectrometric measurements of the isotopic anatomies of molecules (Invited)

    NASA Astrophysics Data System (ADS)

    Eiler, J. M.; Krumwiede, D.; Schlueter, H.

    2013-12-01

    Site-specific and multiple isotopic substitutions in molecular structures potentially provide an extraordinarily rich set of constraints on their sources, conditions of formation, reaction and transport histories, and perhaps other issues. Examples include carbonate ';clumped isotope' thermometry, clumped isotope measurements of CO2, O2, and, recently, methane, ethane and N2O; site-specific 15N measurements in N2O and 13C and D analyses of fatty acids, sugars, cellulose, food products, and, recently, n-alkanes. Extension of the principles behind these tools to the very large number of isotopologues of complex molecules could potentially lead to new uses of isotope chemistry, similar to proteomics, metabolomics and genomics in their complexity and depth of detail (';isotomics'?). Several technologies are potentially useful for this field, including ';SNIF-NMR', gas source mass spectrometry and IR absorption spectroscopy. However, all well established methods have restrictive limits in the sizes of samples, types of analyzes, and the sorts of isotopologues that can be measured with useful precision. We will present an overview of several emerging instruments and techniques of high-resolution gas source mass spectrometry that may enable study of a large proportion of the isotopologues of a wide range of volatile and semi-volatile compounds, including many organics, with precisions and sample sizes suitable for a range of applications. A variety of isotopologues can be measured by combining information from the Thermo 253 Ultra (a new high resolution, multi-collector gas source mass spectrometer) and the Thermo DFS (a very high resolution single collector, but used here on a novel mode to achieve ~per mil precision ratio measurements), sometimes supplemented by conventional bulk isotopic measurements. It is possible to design methods in which no one of these sources of data meaningfully constrain abundances of specific isotopologues, but their combination fully and

  1. Shifts in stable-isotope signatures confirm parasitic relationship of freshwater mussel glochidia attached to host fish

    USGS Publications Warehouse

    Fritts, Mark W.; Fritts, Andrea K.; Carleton, Scott A.; Bringolf, Robert B.

    2013-01-01

    The parasitic nature of the association between glochidia of unionoidean bivalves and their host fish (i.e. the role of fish hosts in providing nutritional resources to the developing glochidia) is still uncertain. While previous work has provided descriptions of development of glochidia on fish hosts, earlier studies have not explicitly documented the flow of nutrition from the host fish to the juvenile mussel. Therefore, our objective was to use stable isotope analysis to quantitatively document nutrient flow between fish and glochidia. Glochidia were collected from nine adult Lampsilis cardium and used to inoculate Micropterus salmoides(n = 27; three fish per maternal mussel) that produced juvenile mussels for the experiment. Adult mussel tissue samples, glochidia, transformed juvenile mussels and fish gill tissues were analysed for δ15N and δ13C isotope ratios. We used a linear mixing model to estimate the fraction of juvenile mussel tissue derived from the host fish's tissue during attachment. Our analyses indicate a distinct shift in both C and N isotopic ratios from the glochidial stage to the juvenile stage during mussel attachment and development. Linear mixing model analysis indicated that 57.4% of the δ15N in juvenile tissues were obtained from the host fish. This work provides novel evidence that larval unionoideans are true parasites that derive nutrition from host fish during their metamorphosis into the juvenile stage.

  2. Ontogenetic shifts in the diet of plains hog-nosed snakes (Heterodon nasicus) revealed by stable isotope analysis.

    PubMed

    Durso, Andrew M; Mullin, Stephen J

    2017-02-01

    Wild snake diets are difficult to study using traditional methods, but stable isotopes offer several advantages, including integrating dietary information over time, providing data from individuals that have not fed recently, and avoiding bias towards slowly-digesting prey items. We used stable isotope signatures of carbon and nitrogen from scale tissue, red blood cells, and blood plasma to assess the diet of wild plains hog-nosed snakes (Heterodon nasicus) in Illinois. We developed Bayesian mixing models which, taken together, predicted that H. nasicus shifted from a juvenile diet predominantly (31-63%) composed of six-lined racerunners (Aspidoscelis sexlineatus) and their eggs to an adult diet predominantly (44-56%) composed of eggs of the aquatic turtles Chrysemys picta and Chelydra serpentina, with a contribution from toads (Anaxyrus sp.; 6-27%) during their adolescent years. These results agreed with sparse data from gut contents. Combining traditional and isotopic techniques for studying the diets of wild snakes can increase the utility of both types of data.

  3. Resonance ionization mass spectrometry for isotopic abundance measurements

    NASA Technical Reports Server (NTRS)

    Miller, C. M.

    1986-01-01

    Resonance ionization mass spectrometry (RIMS) is a relatively new laser-based technique for the determination of isotopic abundances. The resonance ionization process depends upon the stepwise absorption of photons from the laser, promoting atoms of the element of interest through progressively higher electronic states until an ion is formed. Sensitivity arises from the efficiency of the resonant absorption process when coupled with the power available from commercial laser sources. Selectivity derives naturally from the distinct electronic structure of different elements. This isobaric discrimination has provided the major impetus for development of the technique. Resonance ionization mass spectrometry was used for analysis of the isotopic abundances of the rare earth lutetium. Isobaric interferences from ytterbium severely effect the ability to measure small amounts of the neutron-deficient Lu isotopes by conventional mass spectrometric techniques. Resonance ionization for lutetium is performed using a continuous-wave laser operating at 452 nm, through a sequential two-photon process, with one photon exciting the intermediate resonance and the second photon causing ionization. Ion yields for microgram-sized quantities of lutetium lie between 10(6) and 10(7) ions per second, at overall ionization efficiencies approaching 10(-4). Discrimination factors against ytterbium greater than 10(6) have been measured. Resonance ionization for technetium is also being explored, again in response to an isobaric interference, molybdenum. Because of the relatively high ionization potential for Tc, three-photon, two-color RIMS processes are being developed.

  4. Evaluating Nitrogen Isotope Measurements in Unconventional Hydrocarbon Reservoirs

    NASA Astrophysics Data System (ADS)

    Quan, T. M.; Rivera, K.; Adigwe, E.; Riedinger, N.; Puckette, J.

    2014-12-01

    Nitrogen isotope (δ15N) measurements from core samples taken from unconventional hydrocarbon reservoirs may provide important information on depositional environment, reservoir characterization, and post-depositional processes. In order to evaluate the potential of nitrogen isotopes as geochemical proxies for resource evaluation, we measured δ15Nbulk values for six Woodford Shale (Late Devonian-Early Mississippian) cores and three Caney Shale (Early Mississippian) cores and compared the profiles with other geochemical, lithological, maturation, and well-log data. The strongest correlation is between δ15Nbulk and redox-sensitive trace metals and other redox proxies, as predicted by previous research into δ15Nbulk values. This indicates that δ15Nbulk can be used in unconventional reservoirs as a proxy for depositional redox conditions. Unlike other redox proxies, δ15Nbulk reflects the redox state of the deep-water column, rather than that of the deposited sediment, providing a representation of water column processes during deposition. The δ15Nbulk proxy also appears not to be overprinted by catagenic processes. Associations of δ15Nbulk with thermal maturity, gamma ray response, and catagenesis and diagenesis proxies were found to be minimal. The δ15Nbulk profiles do not appear to be overprinted during catagenesis and therefore are not a reliable record of post-depositional processes. Including nitrogen isotope analyses in a geochemical assessment can provide valuable information about the original redox state of the reservoir unit, and assist in characterizing depositional environment.

  5. Neutron inelastic scattering measurements on the stable isotopes of titanium

    NASA Astrophysics Data System (ADS)

    Olacel, A.; Belloni, F.; Borcea, C.; Boromiza, M.; Dessagne, P.; Henning, G.; Kerveno, M.; Negret, A.; Nyman, M.; Pirovano, E.; Plompen, A. J. M.

    2017-07-01

    The results of a neutron inelastic scattering experiment performed at the Geel Electron Linear Accelerator pulsed white neutron source of the European Commission Joint Research Centre are reported. The neutrons with energies up to 18 MeV interacted with a natTi sample and the γ rays resulting from inelastic scattering reactions on the stable isotopes were detected using the Gamma Array for Inelastic Neutron Scattering (GAINS) spectrometer. We were able to measure the γ -production cross sections for 21 transitions in the five stable Ti isotopes. From these, the level cross sections and the total inelastic cross sections were determined. Our experimental results are compared with theoretical calculations performed using the talys 1.8 code, evaluated nuclear data libraries, and also with previously reported results.

  6. Cross-Section Measurements with the Radioactive Isotope Accelerator (RIA)

    SciTech Connect

    Stoyer, M A; Moody, K J; Wild, J F; Patin, J B; Shaughnessy, D A; Stoyer, N J; Harris, L J

    2002-11-19

    RIA will produce beams of exotic nuclei of unprecedented luminosity. Preliminary studies of the feasibility of measuring cross-sections of interest to the science based stockpile stewardship (SBSS) program will be presented, and several experimental techniques will be discussed. Cross-section modeling attempts for the A = 95 mass region will be shown. In addition, several radioactive isotopes could be collected for target production or medical isotope purposes while the main in-beam experiments are running. The inclusion of a broad range mass analyzer (BRAMA) capability at RIA will enable more effective utilization of the facility, enabling the performance of multiple experiments at the same time. This option will be briefly discussed.

  7. In situ measurements of Li isotopes in foraminifera

    NASA Astrophysics Data System (ADS)

    Vigier, Nathalie; Rollion-Bard, Claire; Spezzaferri, Silvia; Brunet, Fabrice

    2007-01-01

    In situ measurement of Li isotope ratios in foraminifera has been developed using a Cameca ims 1270 ion microprobe. In situ δ7Li analyses have been performed in biogenic calcite of planktonic foraminifera from various locations. Results show that for west Pacific mixed Globigerinoides and Globorotalia (22°S161°E), the isotopic variability between tests and within a single test, respectively, is not significantly greater than estimated analytical uncertainty (˜1.5‰). Mean δ7Li for several planktonic foraminifera tests corresponds to the seawater value, strongly suggesting negligible Li isotope fractionation relative to seawater, as previously inferred by Hall et al. (2005) using thermo-ionization mass spectrometer and multicollector-inductively coupled plasma-mass spectrometry techniques. Combined with scanning electron microscopy and ion microprobe imaging, micron-sized grains, enriched in lithium, silica and aluminum have been found in the foraminifera calcite matrix. A simple mixing model shows that 0.3-2 wt % of marine clays incorporated within the analyzed calcite would lower the foraminifera δ7Li value, by 3‰ to 10‰ relative to the isotopic composition of the pure calcite. By comparison, no such grains have been detected in corals. The presence of micron-sized silicate grains embedded within the foraminifera calcite is consistent with the Erez (2003) biomineralization model, involving calcite precipitation from seawater vacuoles. By contrast, coral calcium carbonate is instead precipitated from ions, which have been pumped or diffused through several membranes, impermeable to micrometric grains. Ion microprobe in situ δ7Li measurements in biogenic calcite present new methods for investigating both biomineralization processes and the past record of the ocean composition by exploring geochemical variations at a scale that is smaller in space and in time.

  8. Isotope shifts of the 6d{sup 2} D{sub 3/2}-7 p{sup 2} P{sub 1/2} transition in trapped short-lived {sup 209-214}Ra{sup +}

    SciTech Connect

    Giri, G. S.; Versolato, O. O.; Berg, J. E. van den; Boell, O.; Dammalapati, U.; Hoek, D. J. van der; Jungmann, K.; Kruithof, W. L.; Mueller, S.; Nunez Portela, M.; Onderwater, C. J. G.; Santra, B.; Timmermans, R. G. E.; Wansbeek, L. W.; Willmann, L.; Wilschut, H. W.

    2011-08-15

    Laser spectroscopy of short-lived radium isotopes in a linear Paul trap has been performed. The isotope shifts of the 6d{sup 2} D{sub 3/2} -7 p{sup 2} P{sub 1/2} transition in {sup 209-214}Ra{sup +}, which are sensitive to the short-range part of the atomic wave functions, were measured. The results are essential experimental input for improving the precision of atomic structure calculations. This is indispensable for parity violation in Ra{sup +} aiming at the determination of the weak mixing angle.

  9. Spectroscopic metrology for isotope composition measurements and transfer standards

    NASA Astrophysics Data System (ADS)

    Anyangwe Nwaboh, Javis; Balslev-Harder, David; Kääriäinen, Teemu; Richmond, Craig; Manninen, Albert; Mohn, Joachim; Kiseleva, Maria; Petersen, Jan C.; Werhahn, Olav; Ebert, Volker

    2017-04-01

    The World Meteorological Organization (WMO) has identified greenhouse gases such as CO2, CH4 and N2O as critical for global climate monitoring. Other molecules such as CO that has an indirect effect of enhancing global warming are also monitored. WMO has stated compatibility goals for atmospheric concentration and isotope ratio measurements of these gases, e.g. 0.1 ppm for CO2 concentration measurements in the northern hemisphere and 0.01 ‰ for δ13C-CO2. For measurements of the concentration of greenhouse gases, gas analysers are typically calibrated with static gas standards e.g. traceable to the WMO scale or to the International System of Units (SI) through a national metrology institute. However, concentrations of target components, e.g. CO, in static gas standards have been observed to drift, and typically the gas matrix as well as the isotopic composition of the target component does not always reflect field gas composition, leading to deviations of the analyser response, even after calibration. The deviations are dependent on the measurement technique. To address this issue, part of the HIGHGAS (Metrology for high-impact greenhouse gases) project [1] focused on the development of optical transfer standards (OTSs) for greenhouse gases, e.g. CO2 and CO, potentially complementing gas standards. Isotope ratio mass spectrometry (IRMS) [2] is currently used to provide state-of-the-art high precision (in the 0.01 ‰ range) measurements for the isotopic composition of greenhouse gases. However, there is a need for field-deployable techniques such as optical isotope ratio spectroscopy (OIRS) that can be combined with metrological measurement methods. Within the HIGHGAS project, OIRS methods and procedures based on e.g. cavity enhanced spectroscopy (CES) and tunable diode laser absorption spectroscopy (TDLAS), matched to metrological principles have been established for the measurement of 13C/12C and 18O/16O ratios in CO2, 15N/14N ratios in N2O, and 13C/12C and 2H

  10. The use of reference materials in isotope measurements (Invited)

    NASA Astrophysics Data System (ADS)

    Kessel, R.

    2009-12-01

    Over the last few decades, mass spectrometry has emerged as one of the most important tools for chemical analysis. Isotope measurements on modern mass spectrometers have achieved unprecedented repeatability due to the semi-automated nature and stability. As a consequence of these high precisions, one of the most important factors for improving the total uncertainty of the measurement results is associated with the reference materials used for calibration. Different metrological concepts have been developed to deal with this problem. This talk will examine the impact of these concepts involving reference materials on the uncertainty budget, traceability and comparability of the results.

  11. Measurements of Volatile Circumstellar Isotopes: Effects of Fractionation vs. Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Milam, Stefanie

    The origin, evolution, and fate of our Universe and/or Galaxy have puzzled humankind for centuries. One approach to answering this question is to gain further understanding of stellar evolution, since stars are fundamental in galaxy development and evolution. A compilation of stellar composition can reveal the age, dynamics, and possibly the evolutionary state of a galaxy. In particular the volatile isotope ratios carry an imprint of stellar evolution and nucleosynthesis. Primitive materials, such as meteorites and IDPs, have revealed a component of ``atypical" isotopic signatures of these fundamental elements denoting a possible stellar origin. Understanding the processes by which these elements derive is essential for astrophysics on cosmochemical, galactic, stellar, and planetary scales. We propose to analyze data obtained from the Herschel Space Observatory of circumstellar envelopes to definitively measure C, N, and O isotope ratios and test current models of photo-selective isotope fractionation vs. nucleosynthetically determined values. This proposal augments data from the Herschel Space Observatory, primarily from the HIFISTARS program and MESS, though the entire Herschel archive will be searched for relevant data. The broader implications for this study include fundamental data necessary for furthering our current understanding of stellar nucleosynthesis, circumstellar chemistry, Galactic chemical evolution, and the origin of presolar grains found in primitive materials. We will focus on isotopologues of species formed in thermochemical equilibrium and trace their natal, nucleosynthetic isotope ratios. We will analyze Herschel data obtained for a survey of evolved stars with varying degrees of nuclear processing, evolutionary states, and envelope chemistry (e.g. oxygen-rich vs. carbon-rich). A full circumstellar model will be developed for each source to address specific affects that may influence either the ratios or chemistry. The isotope ratios of 12C

  12. Integrating Ontogenetic Shift, Growth and Mortality to Determine a Species' Ecological Role from Isotopic Signatures

    PubMed Central

    Fontoura, Nelson F.; Rodrigues, Lúcia R.; Batista, Cibele B.; Persch, Tanilene S. P.; Janowicz, Mariola E.

    2015-01-01

    Understanding species linkages and energy transfer is a basic goal underlying any attempt at ecosystem analysis. Although the first food-web studies were based on gut contents of captured specimens, the assessment of stable isotopes, mainly δ13C and δ15N, has become a standard methodology for wide-range analyses in the last 30 years. Stable isotopes provide information on the trophic level of species, food-web length, and origin of organic matter ingested by consumers. In this study, we analyzed the ontogenetic variability of δ13C and δ15N obtained from samples of three Neotropical fish species: silver sardine (Lycengraulis grossidens, n=46), white lambari (Cyanocharax alburnus, n= 26), and the red-tail lambari (Astyanax fasciatus, n=23) in Pinguela Lagoon, southern Brazil. We developed a new metric, called the Weighted Isotopic Signature (φ 15N or φ 13C, ‰), that incorporates ontogenetic variability, body growth, and natural mortality into a single number. PMID:25996777

  13. Edge technique for measurement of laser frequency shifts including the Doppler shift

    NASA Technical Reports Server (NTRS)

    Korb, Larry (Inventor)

    1991-01-01

    A method is disclosed for determining the frequency shift in a laser system by transmitting an outgoing laser beam. An incoming laser beam having a frequency shift is received. A first signal is acquired by transmitting a portion of the incoming laser beam to an energy monitor detector. A second signal is acquired by transmitting a portion of the incoming laser beam through an edge filter to an edge detector, which derives a first normalized signal which is proportional to the transmission of the edge filter at the frequency of the incoming laser beam. A second normalized signal is acquired which is proportional to the transmission of the edge filter at the frequency of the outgoing laser beam. The frequency shift is determined by processing the first and second normalized signals.

  14. Beta Decay Measurements of Neutron Deficient Cesium Isotopes.

    NASA Astrophysics Data System (ADS)

    Parry, Roger Franklin

    The study of nuclei far from beta stability provides information on nuclear binding energies and nuclear structure. However, as one progresses away from the valley of stability, the associated half-lives and production cross sections decrease with increasing interference from the decays of adjacent nuclei. An experimental solution to these problems was the use of the He-jet fed on-line mass separator, RAMA. This instrument provided a fast and selective technique for the mass separation necessary for the investigation of exotic nuclei. Using this device, a beta decay Q-value study of the neutron deficient cesium isotopes, ('119-123)Cs, was conducted. Beta decay endpoint energy measurements of the neutron deficient cesium isotopes were done using an energy spectrum shape fitting technique. This was a departure from the typical method of endpoint energy analysis, the Fermi-Kurie plot. A discussion of the shape fitting procedure and its improved features are discussed. These beta endpoint measurements have led to total decay energies (Q(,EC)) of the neutron deficient ('119 -123)Cs isotopes. The total decay energies of ('122m)Cs (Q(,EC) = 6.95 (+OR-) 0.25 MeV) and ('119)Cs (Q(,EC) = 6.26 (+OR-) 0.29 MeV) were new measurements. The total decay energies of ('123)Cs (Q(,EC) = 4.05 (+OR-) 0.18 MeV), ('122g)Cs (Q(,EC) = 7.05 (+OR-) 0.18 MeV), ('121)Cs (Q(,EC) = 5.21 (+OR-) 0.22 MeV), and ('120)Cs (Q(,EC) = 7.38 (+OR -) 0.23 MeV) were measurements with significantly improved uncertainties as compared to the literature. Further, a combination of the energy levels derived from previous literature gamma-gamma coincident measurements and the experimental beta-coincident gamma decay energies has supported an improved level scheme for ('121)Xe and the proposal of three new energy levels in ('119)Xe. Comparison of the experimental cesium mass excesses (determined with our Q(,EC) values and known xenon mass excesses) with both the literature and theoretical predicted values showed

  15. Mobile measurement of methane: plumes, isotopes and inventory verification

    NASA Astrophysics Data System (ADS)

    Lowry, D.; Zazzeri, G.; Fisher, R. E.; France, J.; Al-Shalaan, A.; Lanoisellé, M.; Nisbet, E. G.

    2015-12-01

    Since 2013 the RHUL group has been identifying methane plumes from major UK sources using a Picarro 2301 coupled to the A0941 mobile module. Once identified the plumes have been sampled by filling Tedlar or Flexfoil bags for later carbon isotopic analysis by high-precision IRMS. This method has ben successfully deployed to isotopically characterize the main anthropogenic methane emitters in the UK (natural gas, coal, landfill, wastewater treatment, cattle; Zazzeri et al., 2015) and during overseas campaigns in eastern Australia (coal, cattle, legacy gas wells) and Kuwait (landfill, wastewater treatment, oil refineries, cattle, camels). This has identified strong similarities of isotopic signature for some sources (landfill, cattle), but large variations for others (natural gas, coal), which must be isotopically resolved at regional scale. Both landfill and natural gas emissions in SE England have tightly-constrained δ13C signatures, averaging -58 ± 3‰ and -36 ± 2‰, respectively, the latter being characteristic of homogenised North Sea gas supply. In contrast, signatures for coal mines in England and Wales fall in a range of 51.2 ± 0.3‰ to 30.9 ± 1.4‰, but can be tightly constrained by region. On a local scale in west London, repeat surveys in the boroughs of Hounslow and Runnymede have been made for comparison with the latest 1x1 km grid UK inventories for 2009 and 2012, which are subdivided by UNECE categories. An excess methane map can be derived for comparison with inventory emissions maps by identifying daily background and binning the excess values from mobile measurements by grid-square. This shows that the spatial distribution of emissions in the UK 2012 inventory is a big improvement on that of 2009. It also suggests that there is an overestimation of emissions from old landfills (closed before 2000 and reliant on a topsoil cap for oxidation), and an underestimation on emissions from currently active landfill cells. Zazzeri, G. et al. (2015

  16. Isotopic measurements of N2O in a hypersaline pond

    NASA Astrophysics Data System (ADS)

    Peters, B. D.; Casciotti, K.; Samarkin, V.; Joye, S. B.; Madigan, M.; Schutte, C.

    2012-12-01

    Production of nitrous oxide (N2O) in aquatic environments has often been attributed to biological processes. However, reports of abiotic mechanisms of N2O production have suggested that such processes may be substantial in Antarctic Dry Valley soils. It has been proposed that the reduction of nitrate (NO3-) and nitrite (NO2-) coupled to Fe (II) oxidation can produce N2O with a characteristic site preference (SP), where SP is defined as the difference in nitrogen isotope ratio between the center and outside nitrogen atoms in the linear N2O molecule. The current study uses isotopic measurements of N2O, NO2-, and NO3- to examine N2O production mechanisms in Don Juan Pond (DJP), a hypersaline pond in the McMurdo Dry Valleys, Antarctica. [NO3-] and [NO2-] in DJP brine were quite high, ranging from 6,238 to 7,719μM and 23 to 36μM, respectively. N2O samples from pond water (brine) yielded δ15Nbulk of -38±1‰, δ18O of +60±2‰, and SP of +1±7‰. Gas collected from soil had similar N2O isotope ratios, with δ15Nbulk of -45±4‰, δ18O of +56±3‰, and SP of +6±1‰. These field measurements were interpreted using a two end member mixing model, in which the measured N2O was assumed to be a mixture between atmospheric N2O and N2O from a local source. Using the three isotope systems (δ15Nbulk, δ18O, and SP), a series of four equations were constructed with five unknowns: δ15Nbulk, δ18O, and SP of the source, and the fractional contributions of the local source and atmospheric N2O. Solving the equations required an assumption about one of the five unknowns. To do this, we used data from laboratory experiments carried out with sterile brine and DJP soil in order to provide an estimate of the N2O isotope signature of the abiotic source. DJP brine and soil measurements gave similar model results, and thus only results using DJP soil measurements are reported here. Assuming δ18O of the unknown local source is near +82‰(from abiotic laboratory experiments), then

  17. Regime shifts in the Arctic North Atlantic during the Neoglacial revealed by seabirds and precipitation isotopes on Bjørnøya, Svalbard

    NASA Astrophysics Data System (ADS)

    D'Andrea, William J.; Hormes, Anne; Bakke, Jostein; Nicolaisen, Line

    2016-04-01

    The northeastern North Atlantic Ocean, and the Norwegian and Greenland Seas are subject to large hydrographic changes. These variations can influence oceanic heat transport to the Arctic, meridional overturning circulation, and atmospheric circulation patterns and thereby impact global climate patterns. Marine records suggest that numerous large-scale changes in the hydrography of the northern North Atlantic took place during the middle to late Holocene. We report a record of nitrogen and hydrogen isotope measurements from a lake sediment core from Bjørnøya, Svalbard (74.38°N, 19.02°E) that documents major regime shifts in the climate of the northern North Atlantic during the past 6,000 years. Bjørnøya is the nesting ground for one of the largest seabird populations in the North Atlantic. As top predators in the marine ecosystem, seabirds (and their guano) are enriched in 15N; during spring and summer months they deliver isotopically enriched nitrogen to nesting areas. We developed a record of seabird population changes on Bjørnøya based on the nitrogen isotope composition of sediments in a core collected from lake Ellasjøen. The record reveals multiple multicentennial scale changes in δ15N values (varying between ~8-12‰) that track past changes in the size of seabird populations. From the same sediment core, we also developed a record of δD of precipitation, using δD values of sedimentary n-alkanes. Past intervals with the largest inferred bird populations correspond with the most enriched δD of precipitation, which we interpret to represent a more Atlantic climate. Periods with reduced seabird populations correspond with intervals with more negative δD of precipitation and representing a more Arctic climate. Together, the nitrogen and hydrogen isotope records signify regime shifts in the oceanography, marine ecosystem, and atmospheric circulation of the northern North Atlantic that are related to variations in the strength of the subpolar gyre.

  18. Measurement of picosecond lifetimes in neutron-rich Xe isotopes

    NASA Astrophysics Data System (ADS)

    Ilieva, S.; Kröll, Th.; Régis, J.-M.; Saed-Samii, N.; Blanc, A.; Bruce, A. M.; Fraile, L. M.; de France, G.; Hartig, A.-L.; Henrich, C.; Ignatov, A.; Jentschel, M.; Jolie, J.; Korten, W.; Köster, U.; Lalkovski, S.; Lozeva, R.; Mach, H.; Mǎrginean, N.; Mutti, P.; Paziy, V.; Regan, P. H.; Simpson, G. S.; Soldner, T.; Thürauf, M.; Ur, C. A.; Urban, W.; Warr, N.

    2016-09-01

    Background: Lifetimes of nuclear excited states in fission fragments have been studied in the past following isotope separation, thus giving access mainly to the fragments' daughters and only to long-lived isomeric states in the primary fragments. For the first time now, short-lived excited states in the primary fragments, produced in neutron-induced prompt fission of 235U and 241Pu, were studied within the EXILL&FATIMA campaign at the intense neutron-beam facility of the Institute Laue-Langevin in Grenoble. Purpose: We aim to investigate the quadrupole collective properties of neutron-rich even-even 138,140,142Xe isotopes lying between the double shell closure N =82 and Z =50 and a deformed region with octupole collectivity. Method: The γ rays emitted from the excited fragments were detected with a mixed array consisting of 8 HPGe EXOGAM Clover detectors (EXILL) and 16 LaBr3(Ce) fast scintillators (FATIMA). The detector system has the unique ability to select the interesting fragment making use of the high resolution of the HPGe detectors and determine subnanosecond lifetimes using the fast scintillators. For the analysis the generalized centroid difference method was used. Results: We show that quadrupole collectivity increases smoothly with increasing neutron number above the closed N =82 neutron shell. Our measurements are complemented by state-of-the-art theory calculations based on shell-model descriptions. Conclusions: The observed smooth increase in quadrupole collectivity is similar to the evolution seen in the measured masses of the xenon isotopic chain and is well reproduced by theory. This behavior is in contrast to higher Z even-even nuclei where abrupt change in deformation occurs around N =90 .

  19. Laser Ablation Molecular Isotopic Spectrometry: Strontium and its isotopes

    NASA Astrophysics Data System (ADS)

    Mao, Xianglei; Bol'shakov, Alexander A.; Choi, Inhee; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman; Russo, Richard E.

    2011-11-01

    The experimental details are reported of Laser Ablation Molecular Isotopic Spectrometry (LAMIS) and its application for performing optical isotopic analysis of solid strontium-containing samples in ambient atmospheric air at normal pressure. The LAMIS detection method is described for strontium isotopes from samples of various chemical and isotopic compositions. The results demonstrate spectrally resolved measurements of the three individual 86Sr, 87Sr, and 88Sr isotopes that are quantified using multivariate calibration of spectra. The observed isotopic shifts are consistent with those calculated theoretically. The measured spectra of diatomic oxide and halides of strontium generated in laser ablation plasmas demonstrate the isotopic resolution and capability of LAMIS. In particular, emission spectra of SrO and SrF molecular radicals provided clean and well resolved spectral signatures for the naturally occurring strontium isotopes. A possibility is discussed of using LAMIS of strontium isotopes for radiogenic age determination.

  20. Iron and Nickel Isotopic Compositions of Presolar Silicon Carbide Grains from AGB Stars Measured with CHILI

    NASA Astrophysics Data System (ADS)

    Trappitsch, R.; Stephan, T.; Davis, A. M.; Pellin, M. J.; Savina, M. R.; Gyngard, F.; Bisterzo, S.; Gallino, R.; Dauphas, N.

    2016-08-01

    Simultaneous iron and nickel isotopic studies in presolar SiC mainstream grains measured on CHILI show the expected AGB star anomalies in the neutron-rich isotopes. Neutron-poor isotopes are dominated by GCE and show clear correlations with silicon.

  1. The0ry 0f Dipolon-Phonom Interaction and Isotope Shift in Superconducting Cuprates

    NASA Astrophysics Data System (ADS)

    Sharma, Ram

    2011-03-01

    Quite recently we have deduced five principles of photoemission and not only we have explained the observed low energy kink but we have also predicted two more high energy kinks [1,2] in quasiparticle energydistribution which have now been observed experimentally, all by means of the dipolon theory [3,4]. Here, the Hamiltonian for the interaction of dipolons with phonons will be presented.The Hamiltonian requires the evaluation of phonon-generated dynamic polarization fields at the oxygen sites in the Cu -O2 -planes. The quasi-dipolons (phonon-dressed dipolons) now play role as mediators of electron-electron pairing. Expression for the change in the transition temprature TC due to change in oxygen isotopic mass has been derived. We have found a small decrease of about 1 per cent in TC due to 16 O -->18 O , in agree ment with experiments. The change in dipolon frequencies owing to the interaction with phonons has been calculated.

  2. Beta-decay measurements of neutron-deficient cesium isotopes

    SciTech Connect

    Parry, R.F.

    1983-03-01

    Beta decay endpoint energy measurements of the neutron deficient cesium isotopes were done using an energy spectrum shape fitting technique. This was a departure from the typical method of endpoint energy analysis, the Fermi-Kurie plot. A discussion of the shape fitting procedure and its improved features are discussed. These beta endpoint measurements have led to total decay energies (Q/sub EC/) of the neutron deficient /sup 119/ /sup 123/Cs isotopes. The total decay energies of /sup 122m/Cs (Q/sub EC/ = 6.95 +- 0.25 MeV) and /sup 119/Cs (Q/sub EC/ = 6.26 +- 0.29 MeV) were new measurements. The total decay energies of /sup 123/Cs (Q/sub EC/ = 4.05 +- 0.18 MeV), /sup 122g/Cs (Q/sub EC/ = 7.05 +- 0.18 MeV), /sup 121/Cs (Q/sub EC/ = 5.21 +- 0.22 MeV), and /sup 120/Cs (Q/sub EC/ = 7.38 +- 0.23 MeV) were measurements with significantly improved uncertainties as compared to the literature. Further, a combination of the energy levels derived from previous literature gamma-gamma coincident measurements and the experimental beta-coincident gamma decay energies has supported an improved level scheme for /sup 121/Xe and the proposal of three new energy levels in /sup 119/Xe. Comparison of the experimental cesium mass excesses (determined with our Q/sub EC/ values and known xenon mass excesses) with both the literature and theoretical predicted values showed general agreement except for /sup 120/Cs. Possible explanations for this deviation are discussed.

  3. Broadband non-selective excitation of plutonium isotopes for isotope ratio measurements in resonance ionization mass spectrometry: a theoretical study.

    PubMed

    Sankari, M

    2012-10-15

    Making isotope ratio measurements with minimum isotope bias has always been a challenging task to mass spectrometrists, especially for the specific case of plutonium, owing to the strategic importance of the element. In order to use resonance ionization mass spectrometry (RIMS) as a tool for isotope ratio measurements, optimization of the various laser parameters and other atomic and system parameters is critical to minimize isotopic biases. Broadband simultaneous non-selective excitation of the isotopes of plutonium in the triple resonance excitation scheme with λ(1) = 420.77 nm, λ(2) = 847.28 nm, and λ(3) = 767.53 nm based on density matrix formalism has been theoretically computed for the determination of isotope ratios. The effects of the various laser parameters and other factors such as the atomization temperature and the dimensions of the atomic beam on the estimation of isotope ratios were studied. The effects of Doppler broadening, and time-dependent excitation parameters such as Rabi frequencies, ionization rate and the effect of non-Lorenztian lineshape have all been incorporated. The average laser powers and bandwidths for the three-excitation steps were evaluated for non-selective excitation. The laser intensity required to saturate the three-excitation steps were studied. The two-dimensional lineshape contour and its features were investigated, while the reversal of peak asymmetry of two-step and two-photon excitation peaks under these conditions is discussed. Optimized powers for the non-selective ionization of the three transitions were calculated as 545 mW, 150 mW and 545 mW and the laser bandwidth for all the three steps was ~20 GHz. The isotopic bias between the resonant and off-resonant isotope under the optimized conditions was no more than 9%, which is better than an earlier reported value. These optimized laser power and bandwidth conditions are better than in the earlier experimental work since these comprehensive calculations yield

  4. On-line measurement of intramolecular carbon isotope distribution of acetic acid by continuous-flow isotope ratio mass spectrometry.

    PubMed

    Yamada, Keita; Tanaka, Misato; Nakagawa, Fumiko; Yoshida, Naohiro

    2002-01-01

    Molecular and intramolecular carbon isotope measurements of acetic acid present in natural environments have been performed by off-line procedures. The off-line method is complicated and time-consuming and requires micromolar to millimolar amounts of sample. This limits geochemical isotopic studies, especially at the intramolecular level, on acetic acid present in natural samples. Here, we examine an on-line measurement of intramolecular carbon isotope distribution of acetic acid using continuous-flow isotope ratio mass spectrometry (CF-IRMS) coupled with an on-line pyrolysis system. This is achieved by measurement of the respective carbon isotope ratios of CH4 and CO2 produced by on-line pyrolysis of acetic acid. Results for authentic standards of pure acetic acid demonstrated the practicality of this on-line method, although the carbon isotope ratio of the methyl group could not be determined directly. The precision of the carbon isotope measurements was 0.4 per thousand (1sigma). The carbon isotope distribution determined by the on-line method was identical to that determined by the conventional off-line method within analytical error. The advantages of the on-line method compared with the conventional off-line method are that it is less laborious, requires less analytical time (less than one hour per sample) and, most importantly, uses smaller sample sizes (ca. 10 nanomole). An application of this on-line method to natural geochemical samples will provide an insight into the geochemical cycle of acetic acid. Copyright 2002 John Wiley & Sons, Ltd.

  5. Surface shape measurement by phase-shifting digital holography with a wavelength shift.

    PubMed

    Yamaguchi, Ichirou; Ida, Takashi; Yokota, Masayuki; Yamashita, Kouji

    2006-10-10

    Surface contouring by phase-shifting digital holography is proposed and verified by experiments and numerical simulations. Digital holograms are recorded before and after mode hopping of a laser diode subject to current tuning, and the difference of the reconstructed phases at each wavelength is computed to deliver surface contours of a diffusely reflecting surface. Since normal incidence on the object is employed, the method does not need the removal of the tilt component and is free from the shadowing effect as advantages over the dual-incidence method proposed before by the first author.

  6. Silicon isotope ratio measurements by inductively coupled plasma tandem mass spectrometry for alteration studies of nuclear waste glasses.

    PubMed

    Gourgiotis, Alkiviadis; Ducasse, Thomas; Barker, Evelyne; Jollivet, Patrick; Gin, Stéphane; Bassot, Sylvain; Cazala, Charlotte

    2017-02-15

    High-level, long-lived nuclear waste arising from spent fuel reprocessing is vitrified in silicate glasses for final disposal in deep geologic formations. In order to better understand the mechanisms driving glass dissolution, glass alteration studies, based on silicon isotope ratio monitoring of (29)Si-doped aqueous solutions, were carried out in laboratories. This work explores the capabilities of the new type of quadrupole-based ICP-MS, the Agilent 8800 tandem quadrupole ICP-MS/MS, for accurate silicon isotope ratio determination for alteration studies of nuclear waste glasses. In order to avoid silicon polyatomic interferences, a new analytical method was developed using O2 as the reaction gas in the Octopole Reaction System (ORS), and silicon isotopes were measured in mass-shift mode. A careful analysis of the potential polyatomic interferences on SiO(+) and SiO2(+) ion species was performed, and we found that SiO(+) ion species suffer from important polyatomic interferences coming from the matrix of sample and standard solutions (0.5M HNO3). For SiO2(+), no interferences were detected, and thus, these ion species were chosen for silicon isotope ratio determination. A number of key settings for accurate isotope ratio analysis like, detector dead time, integration time, number of sweeps, wait time offset, memory blank and instrumental mass fractionation, were considered and optimized. Particular attention was paid to the optimization of abundance sensitivity of the quadrupole mass filter before the ORS. We showed that poor abundance sensitivity leads to a significant shift of the data away from the Exponential Mass Fractionation Law (EMFL) due to the spectral overlaps of silicon isotopes combined with different oxygen isotopes (i.e. (28)Si(16)O(18)O(+), (30)Si(16)O(16)O(+)). The developed method was validated by measuring a series of reference solutions with different (29)Si enrichment. Isotope ratio trueness, uncertainty and repeatability were found to be <0

  7. Theoretical investigation of the isomer shifts of the 119Sn Mössbauer isotope

    NASA Astrophysics Data System (ADS)

    Svane, A.; Antoncik, E.

    1987-04-01

    We solve the electronic structure problem self-consistently for a series of crystalline solids, containing Sn as a component, with the use of the first-principles scalar-relativistic linear muffin-tin-orbital method in the local-density approximation. The crystals considered are the two allotropes α-Sn and β-Sn as well as the compounds SnO2, SnMg2, SnSb, and SnTe. The derived band structure is discussed and compared to previous calculations and experimental information. By extension of the radial integration of the Dirac equation to well within the nuclear regime, the valence-electron contribution to the charge density on the nuclear site is obtained. Excellent agreement is found when comparing with experimental isomer shifts. A value of ΔR/R=(1.34+/-0.07)×10-4 for the relative change of the radius of the 119Sn nucleus upon excitation is deduced. The observed trends in the isomer shifts are interpreted on the basis of the decomposition of the crystal wave function into angular momentum character.

  8. Light-shift measurement and suppression in atomic spin gyroscope.

    PubMed

    Fang, Jiancheng; Wan, Shuangai; Chen, Yao; Li, Rujie

    2012-11-01

    We present a method to determine and suppress the light shift in an atomic spin gyroscope. This method doesn't require additional drive source or frequency modulation, and it is based on the dynamics of an atomic spin gyroscope to determine a clean curve as a function of the frequency of the pump beam that predicts the zero light shift. We experimentally validate the method in a Cs-(129)Xe atomic spin gyroscope and verify the results through numerical simulations. This method can also be applied to an atomic spin magnetometer based on the spin-exchange relaxation-free exchange that experiences light shift. The method is useful for atomic spin devices because it can improve long-term performance and reduce the influence of the laser.

  9. Steps toward identifying a biogeochemical signal in non-equilibrium methane clumped isotope measurements

    NASA Astrophysics Data System (ADS)

    Douglas, P. M.; Eiler, J. M.; Sessions, A. L.; Dawson, K.; Walter Anthony, K. M.; Smith, D. A.; Lloyd, M. K.; Yanay, E.

    2016-12-01

    Microbially produced methane is a globally important greenhouse gas, energy source, and biological substrate. Methane clumped isotope measurements have recently been developed as a new analytical tool for understanding the source of methane in different environments. When methane forms in isotopic equilibrium clumped isotope values are determined by formation temperature, but in many cases microbial methane clumped isotope values deviate strongly from expected equilibrium values. Indeed, we observe a very wide range of clumped isotope values in microbial methane, which are likely strongly influenced by kinetic isotope effects, but thus far the biological and environmental parameters controlling this variability are not understood. We will present data from both culture experiments and natural environments to explore patterns of variability in non-equilibrium clumped isotope values on temporal and spatial scales. In methanogen batch cultures sampled at different time points along a growth curve we observe significant variability in clumped isotope values, with values decreasing from early to late exponential growth. Clumped isotope values then increase during stationary growth. This result is consistent with previous work suggesting that differences in the reversibility of methanogenesis related to metabolic rates control non-equilibrium clumped isotope values. Within single lakes in Alaska and Sweden we observe substantial variability in clumped isotope values on the order of 5‰. Lower clumped isotope values are associated with larger 2H isotopic fractionation between water and methane, which is also consistent with a kinetic isotope effect determined by the reversibility of methanogenesis. Finally, we analyzed a time-series clumped isotope compositions of methane emitted from two seeps in an Alaskan lake over several months. Temporal variability in these seeps is on the order of 2‰, which is much less than the observed spatial variability within the lake

  10. Carbon Isotope Measurements of Experimentally-Derived Hydrothermal Mineral-Catalyzed Organic Products by Pyrolysis-Isotope Ratio Mass Spectrometry

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.

    2011-01-01

    We report results of experiments to measure the C isotope composition of mineral catalyzed organic compounds derived from high temperature and high pressure synthesis. These experiments make use of an innovative pyrolysis technique designed to extract and measure C isotopes. To date, our experiments have focused on the pyrolysis and C isotope ratio measurements of low-molecular weight intermediary hydrocarbons (organic acids and alcohols) and serve as a proof of concept for making C and H isotope measurements on more complicated mixtures of solid-phase hydrocarbons and intermediary products produced during high temperature and high pressure synthesis on mineral-catalyzed surfaces. The impetus for this work stems from recently reported observations of methane detected within the Martian atmosphere [1-4], coupled with evidence showing extensive water-rock interaction during Martian history [5-7]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization reactions [8,9]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [10-12]. Further, recent experiments by Fu et al. [13] focus on examining detailed C isotope measurements of hydrocarbons produced by surface-catalyzed mineral reactions. Work described in this paper details the experimental techniques used to measure intermediary organic reaction products (alcohols and organic acids).

  11. In-situ Nd isotope measurements on accessory minerals: Insights into isotope equilibration during metamorphism

    NASA Astrophysics Data System (ADS)

    Hammerli, Johannes; Spandler, Carl; Kemp, Tony; Pirard, Cassian

    2015-04-01

    Understanding isotope equilibration processes during metamorphism has huge implications for a range of geoscience applications, ranging from provenance studies of sedimentary units to the origin of magmas and ore bodies. Furthermore, recent claims of isotope disequilibrium situations during the melting of continental crust have questioned the reliability of using certain isotope systems to track magma sources. Our recent work investigated a prograde sequence of high-temperature, low-pressure (350-650 ˚C, ~3-5 kbar) metasedimentary rocks from the Mt. Lofty Ranges, South Australia that underwent widespread pervasive fluid flow at peak metamorphism. In situ Nd-isotope analyses by LA-MC-ICP-MS found that the detrital signature of apatite survives temperatures of 500 °C. However, the observed isotope equilibration of REE-bearing accessory minerals at ~600 °C, before the onset of partial melting, suggests that isotope disequilibrium is unlikely during high-grade metamorphism of upper crustal rocks where fluid induced melting takes place. Here, we extend our research to metasedimentary rocks from (ultra)-high pressure metamorphic terrains from northern New Caledonia, and Dabieshan, China that represent pressure and temperature conditions found in subduction zones. Our study helps to understand isotope equilibration processes from heterogeneous protoliths as well as the impact of retrogression and the resetting of isotope systems over a pressure-temperature range from ~350 °C to 700 °C and ~15 kbar to 40 kbar. Nd isotope analyses of apatite, allanite, titanite, xenotime, monazite, lawsonite and epidote in pelitic and psammitic samples allow the investigation of isotope equilibration on a mineral and sub-mineral scale, as well as comparison with traditional bulk rock isotope analyses. Our preliminary results show that under high-pressure conditions (~20 to 30 kbar) and temperatures to ~650 °C, REE-bearing phases show variable ɛNd values in some cases. These

  12. The TRIple PLunger for EXotic beams TRIPLEX for excited-state lifetime measurement studies on rare isotopes

    NASA Astrophysics Data System (ADS)

    Iwasaki, H.; Dewald, A.; Braunroth, T.; Fransen, C.; Smalley, D.; Lemasson, A.; Morse, C.; Whitmore, K.; Loelius, C.

    2016-01-01

    A new device, the TRIple PLunger for EXotic beams (TRIPLEX), has been developed for lifetime measurement studies with rare isotope beams. This plunger device holds up to three metal foils in the beam path and facilitates the recoil distance Doppler-shift technique to measure lifetimes of nuclear excited states in the range of 1 ps to 1 ns. The unique design allows independent movement of the target and the second degrader with respect to a fixed first degrader in between, enabling advanced experimental approaches, such as the differential recoil distance method and the double recoil distance method. The design and control of the device are presented in this paper, together with simulated performances of the new applications. As an example of actual experiments, results from the lifetime measurement of the neutron-rich 17C isotope performed at the National Superconducting Cyclotron Laboratory are shown.

  13. Combining chemical and isotopic measurements to estimate pesticide degradation rates in a fractured-rock aquifer

    NASA Astrophysics Data System (ADS)

    Farlin, Julien; Gallé, Tom; Bayerle, Michael; Pittois, Denis; El-Khabbaz, Hassanya; Schreglmann, Kathrin; Höche, Martina; Elsner, Martin

    2013-04-01

    Encouraged by new regulatory requirements for pesticide registration and authorization, the transport and environmental fate of these compounds in the different environmental compartments has been studied extensively. Degradation rates vary widely depending on hydraulic and chemical characteristics, with the strongest degradation usually occuring in the topsoil. Nonetheless, significant pesticide attenuation may still take place during transport in the aquifer, since residence times are generally much longer than in the soil. Ideally, pesticide transformation in the aquifer needs to be determined under real field conditions. Mass balance calculations however are complicated by the fact that the initial pesticide mass leached from the soil is often not known precisely enough. In this study, isotopic and classical pesticide concentration measurements were combined with groundwater dating techniques to assess the degradation rate of atrazine and its metabolite desethylatrazine in a fractured sandstone. The mass balance problem was solved by introducing the desethylatrazine to atrazine ratio, a relative measure which was used to quantify the advancement of atrazine degradation with increasing transport time in the subsurface. The extent of transformation of the parent compound was finally estimated from the shift in the isotopic signal between soil application and the outlet of the groundwater system.

  14. Isotope excursions and shifting oxidation states recorded in the Paleoproterozoic Franceville Basin

    NASA Astrophysics Data System (ADS)

    Wang, V.; Junium, C. K.; Lu, Z.; Préat, A.

    2014-12-01

    Geochemical studies of Paleoproterozoic rocks have revealed that the initial rise of oxygen was protracted and that Earth's surface environments fluctuated between oxic and anoxic states over hundreds of millions of years. Marine sediments of the 2.1 Gyr-old Franceville Basin of west central Africa are only lightly metamorphosed, and their geochemistry may thus reveal unique insights into the environmental and metabolic conditions during the history of rising oxygen levels. In the Franceville Basin stratigraphic variation totaling 10‰ in δ13Ccarb was previously documented. This contribution builds on this work and characterizes changes in C, N, and S cycles using stable isotope values. The results from systematic analysis of several biologically mediated redox proxies preserved in carbonates from the Franceville Basin will be presented, including δ34S values of pyrite and δ13C and δ15N values of bulk organic carbon and kerogens. Consistent with independent reports of an excursion in δ13Corg in the Franceville Basin and elsewhere, we find ~20‰ stratigraphic variation in δ13C of bulk organic carbon. Initial results for δ15N of bulk organic matter range from -6 to 6 ‰, a wider distribution of values than previously reported for the Franceville Basin and more negative than values reported for the similarly aged Onega Basin in Fennoscandia. I/Ca ratios range from near zero to near Phanerozoic levels and are consistent with the presence of iodate. Chromium reducible sulfide has been extracted from all but one sample, confirming the presence of pyrite. δ34S of pyrite as well as δ13C and δ15N of kerogen will also be presented. The biochemically diverse array of proxy analyses presented here have varying thresholds of sensitivity to oxygen levels and hence will allow detailed reconstruction of the redox history of basin waters. As minimum O2 thresholds are often needed for certain biochemical processes, the resulting data will also have implications for key

  15. Observations of the Goos-Hanchen and Imbert-Fedorov shifts via weak measurement

    NASA Astrophysics Data System (ADS)

    Kazarina, Oxana

    The Goos-Hanchen (longitudinal) and Imbert-Fedorov (transverse) shifts show that the center of the reflected beam is shifted and doesn't follow the laws of geometrical optics. The beam has to have finite width and be totally internally reflected at an interface of two media having different indices of refraction. Because these shifts are very small (on the wavelength scale) the weak measurements, known from the quantum mechanics, allow to amplify and measure such small phenomena. In this paper the Goos-Hanchen and Imbert-Fedorov spatial shifts were measured experimentally via weak measurement technique which was observed for a linearly polarized beam at total internal reflection.

  16. Measurement of labile Cu in soil using stable isotope dilution and isotope ratio analysis by ICP-MS.

    PubMed

    Nolan, Annette L; Ma, Yibing; Lombi, Enzo; McLaughlin, Mike J

    2004-11-01

    Isotope dilution is a useful technique to measure the labile metal pool, which is the amount of metal in soil in rapid equilibrium (<7 days) with the soil solution. This is normally performed by equilibrating soil with a metal isotope, and sampling the labile metal pool by using an extraction (E value), or by growing plants (L value). For Cu, this procedure is problematic for E values, and impossible for L values, due to the short half-life of the 64Cu radioisotope (12.4 h), which makes access and handling very difficult. We therefore developed a technique using enriched 65Cu stable isotope and measurement of 63Cu/65Cu ratios by quadrupole inductively coupled plasma mass spectrometry (ICP-MS) to measure labile pools of Cu in soils using E value techniques. Mass spectral interferences in detection of 63Cu/65Cu ratios in soil extracts were found to be minimal. Isotope ratios determined by quadrupole ICP-MS compared well to those determined by high-resolution (magnetic sector) ICP-MS. E values determined using the stable isotope technique compared well to those determined using the radioisotope for both uncontaminated and Cu-contaminated soils.

  17. Hydrogen-isotope motion in scandium studied by ultrasonic measurements

    SciTech Connect

    Leisure, R.G. ); Schwarz, R.B.; Migliori, A. ); Torgeson, D.R. ); Svare, I. )

    1993-07-01

    Resonant ultrasound spectroscopy has been used to investigate ultrasonic attenuation in single crystals of Sc, ScH[sub 0.25], and ScD[sub 0.18] over the temperature range of 10--300 K for frequencies near 1 MHz. Ultrasonic-attenuation peaks were observed in the samples containing H or D with the maximum attenuation occurring near 25 K for ScH[sub 0.25] and near 50 K for ScD[sub 0.18]. The general features of the data suggest that the motion reflected in the ultrasonic attenuation is closely related to the low-temperature motion seen in nulcear-magnetic-resonance spin-lattice-relaxation measurements. The ultrasonic results were fit with a two-level-system (TLS) model involving tunneling between highly asymmetric sites. The relaxation of the TLS was found to consist of two parts: a weakly temperature-dependent part, probably due to coupling to electrons; and a much more strongly temperature-dependent part, attributed to multiple-phonon processes. The strongly temperature-dependent part was almost two orders of magnitude faster in ScH[sub 0.25] than in ScD[sub 0.18], in accordance with the idea that tunneling is involved in the motion. Surprisingly, the weakly temperature-dependent part was found to be about the same for the two isotopes. The asymmetries primarily responsible for coupling the TLS to the ultrasound are attributed to interactions between hydrogen ions that lie on adjacent [ital c] axes. The results are consistent with an isotope-independent strength for the coupling of the TLS to the ultrasound.

  18. Scale-dependent linkages between nitrate isotopes and denitrification in surface soils: implications for isotope measurements and models.

    PubMed

    Hall, Steven J; Weintraub, Samantha R; Bowling, David R

    2016-08-01

    Natural abundance nitrate (NO3 (-)) isotopes represent a powerful tool for assessing denitrification, yet the scale and context dependence of relationships between isotopes and denitrification have received little attention, especially in surface soils. We measured the NO3 (-) isotope compositions in soil extractions and lysimeter water from a semi-arid meadow and lawn during snowmelt, along with the denitrification potential, bulk O2, and a proxy for anaerobic microsites. Denitrification potential varied by three orders of magnitude and the slope of δ(18)O/δ(15)N in soil-extracted NO3 (-) from all samples measured 1.04 ± 0.12 (R (2) = 0.64, p < 0.0001), consistent with fractionation from denitrification. However, δ(15)N of extracted NO3 (-) was often lower than bulk soil δ(15)N (by up to 24 ‰), indicative of fractionation during nitrification that was partially overprinted by denitrification. Mean NO3 (-) isotopes in lysimeter water differed from soil extractions by up to 19 ‰ in δ(18)O and 12 ‰ in δ(15)N, indicating distinct biogeochemical processing in relatively mobile water versus soil microsites. This implies that NO3 (-) isotopes in streams, which are predominantly fed by mobile water, do not fully reflect terrestrial soil N cycling. Relationships between potential denitrification and δ(15)N of extracted NO3 (-) showed a strong threshold effect culminating in a null relationship at high denitrification rates. Our observations of (1) competing fractionation from nitrification and denitrification in redox-heterogeneous surface soils, (2) large NO3 (-) isotopic differences between relatively immobile and mobile water pools, (3) and the spatial dependence of δ(18)O/δ(15)N relationships suggest caution in using NO3 (-) isotopes to infer site or watershed-scale patterns in denitrification.

  19. Phase shifting interferometry using a spatial light modulator to measure optical thin films.

    PubMed

    Villalobos-Mendoza, Brenda; Granados-Agustín, Fermín S; Aguirre-Aguirre, Daniel; Cornejo-Rodríguez, Alejandro

    2015-09-10

    This work describes a process for measuring thin film steps, using phase shifting interferometry (PSI). The phase shifts are applied only in the region where the thin film steps are located. The phase shift is achieved by displaying different gray levels on a spatial light modulator (SLM Holoeye LC2012) placed in one arm of a Twyman-Green (T-G) interferometer. Before measuring the thin film steps, it was necessary to quantify the phase shifts achieved with this SLM by measuring the fringe shifts in experimental interferograms. The phase shifts observed in the interference patterns were produced by displaying the different gray levels on the SLM one by one, from 0 to 255. The experimental interferograms and the thicknesses of the thin film steps were successfully quantified, proving that this method can be used to measure thin films by applying the PSI method only on the region occupied by them.

  20. Synthesis, NMR spectroscopic characterization and structure of a divinyldisilazane-(triphenylphosphine)platinum(0) complex: observation of isotope-induced chemical shifts (1)Δ(12/13)C((195)Pt).

    PubMed

    Wrackmeyer, Bernd; Klimkina, Elena V; Schmalz, Thomas; Milius, Wolfgang

    2013-05-01

    Tetramethyldivinyldisilazane-(triphenylphosphine)platinum(0) was prepared, characterized in solid state by X-ray crystallography and in solution by multinuclear magnetic resonance spectroscopy ((1)H, (13)C, (15)N, (29)Si, (31)P and (195)Pt NMR). Numerous signs of spin-spin coupling constants were determined by two-dimensional heteronuclear shift correlations (HETCOR) and two-dimensional (1)H/(1)H COSY experiments. Isotope-induced chemical shifts (1)Δ(12/13)C((195)Pt) were measured from (195)Pt NMR spectra of the title compound as well as of other Pt(0), Pt(II) and Pt(IV) compounds for comparison. In contrast to other heavy nuclei such as (199)Hg or (207)Pb, the "normal" shifts of the heavy isotopomers to low frequencies are found, covering a range of >500 ppb.

  1. Examination of P-OR bridging bond orders in phosphate monoesters using (18)O isotope shifts in 31P NMR.

    PubMed

    Sorensen-Stowell, Kerensa; Hengge, Alvan C

    2005-06-10

    Evidence indicates that phosphate monoesters undergo hydrolysis by a loose transition state with extensive bond fission to the leaving group. It has been proposed that part of the high dependence of the rate on the leaving group pKa (betalg = -1.23) arises from weaker ester bonds in the reactants as the pKa of the leaving group decreases, on the basis of X-ray structures and calculations. In contrast, IR and Raman studies suggest that the leaving group has little effect on the length of the P-OR bridging bond in solution. To gather additional data on this issue, we have used (18)O isotopic shifts in 31P NMR to monitor the bond order of P-O bonds in a range of phosphate esters with different leaving groups. Using this technique, we have been able to evaluate whether significant changes are observed in the P-O bond orders for the bridging and nonbridging positions of methyl, ethyl, phenethyl, propargyl, phenyl, and p-nitrophenyl phosphate using [(16)O(18)O] labeled species in deuterium oxide. The results indicate that the bridging and nonbridging bond orders to phosphorus in phosphate monoesters are not significantly altered by differences in the pKa of the leaving group or by the counterion of the phosphate ester dianion.

  2. Determination of carbon isotopic measurement conditions for ceramide in skin using gas chromatography-combustion-isotope ratio mass spectrometry.

    PubMed

    Haraguchi, Hiroyuki; Yamada, Keita; Miyashita, Rumiko; Aida, Kazuhiko; Ohnishi, Masao; Gilbert, Alexis; Yoshida, Naohiro

    2014-01-01

    The ceramide (Cer) content of skin and glucosylceramide (GlcCer) intake affect skin moisture conditions, but their mutual relation in skin remains unclear. For clarification of that mutual relation, carbon stable isotopes ((12)C and (13)C) are useful as a tracer. However, carbon isotopic measurement has not been applied to the study of clarifying their skin moisturizing effects. Therefore, we used gas chromatography / combustion / isotope ratio mass spectrometry (GC-C-IRMS) to ascertain the appropriate conditions for carbon isotopic measurements using synthesized Cer (SCer) in substitution for very low concentrations of Cer in skin. SCer was derivatized to trimethylsilylated SCer (TMS-SCer) quantitatively using N-trimethylsilylimidazole (TMSI) depending on the amount of SCer. The derivatization rates were 75-85%. Excess TMSI was removed using three cycles of hexane-water distribution. Under these conditions, carbon isotopic measurements of TMS-SCer conducted using GC-C-IRMS showed high repeatability and good inter-day variation (S.D. < 0.3‰). The carbon stable isotope ratio value (δ(13)C) of SCer calculated using a mass balance equation was compared with δ(13)C of underivatized SCer, which was regarded as the actual δ(13)C of SCer obtained using sealed tube combustion method. The difference between the calculated δ(13)C of SCer and δ(13)C of the underivatized SCer depended on the TMSI reagent supplier and on the number of hydroxyl groups to be derivatized in SCer. For accurate δ(13)C of Cer in skin using GC-C-IRMS, the measured δ(13)C of a target TMS-Cer must be calculated using a correction factor representing the difference in δ(13)C of underivatized standard SCer from that of TMS-standard SCer having a structure resembling that of the target Cer in skin. In addition, we show that the same lot of TMSI reagent from a specific supplier must be used throughout the experiments.

  3. Continuous measurements of isotopic composition of water vapour on the East Antarctic Plateau

    NASA Astrophysics Data System (ADS)

    Casado, Mathieu; Landais, Amaelle; Masson-Delmotte, Valérie; Genthon, Christophe; Kerstel, Erik; Kassi, Samir; Arnaud, Laurent; Picard, Ghislain; Prie, Frederic; Cattani, Olivier; Steen-Larsen, Hans-Christian; Vignon, Etienne; Cermak, Peter

    2016-07-01

    Water stable isotopes in central Antarctic ice cores are critical to quantify past temperature changes. Accurate temperature reconstructions require one to understand the processes controlling surface snow isotopic composition. Isotopic fractionation processes occurring in the atmosphere and controlling snowfall isotopic composition are well understood theoretically and implemented in atmospheric models. However, post-deposition processes are poorly documented and understood. To quantitatively interpret the isotopic composition of water archived in ice cores, it is thus essential to study the continuum between surface water vapour, precipitation, surface snow and buried snow. Here, we target the isotopic composition of water vapour at Concordia Station, where the oldest EPICA Dome C ice cores have been retrieved. While snowfall and surface snow sampling is routinely performed, accurate measurements of surface water vapour are challenging in such cold and dry conditions. New developments in infrared spectroscopy enable now the measurement of isotopic composition in water vapour traces. Two infrared spectrometers have been deployed at Concordia, allowing continuous, in situ measurements for 1 month in December 2014-January 2015. Comparison of the results from infrared spectroscopy with laboratory measurements of discrete samples trapped using cryogenic sampling validates the relevance of the method to measure isotopic composition in dry conditions. We observe very large diurnal cycles in isotopic composition well correlated with temperature diurnal cycles. Identification of different behaviours of isotopic composition in the water vapour associated with turbulent or stratified regime indicates a strong impact of meteorological processes in local vapour/snow interaction. Even if the vapour isotopic composition seems to be, at least part of the time, at equilibrium with the local snow, the slope of δD against δ18O prevents us from identifying a unique origin leading

  4. A solvent extraction technique for the isotopic measurement of dissolved copper in seawater.

    PubMed

    Thompson, Claire M; Ellwood, Michael J; Wille, Martin

    2013-05-02

    Stable copper (Cu) isotope geochemistry provides a new perspective for investigating and understanding Cu speciation and biogeochemical Cu cycling in seawater. In this work, sample preparation for isotopic analysis employed solvent-extraction with amino pyrollidine dithiocarbamate/diethyl dithiocarbamate (APDC/DDC), coupled with a nitric acid back-extraction, to concentrate Cu from seawater. This was followed by Cu-purification using anion-exchange. This straightforward technique is high yielding and fractionation free for Cu and allows precise measurement of the seawater Cu isotopic composition using multi-collector inductively coupled plasma mass-spectrometry. A deep-sea profile measured in the oligotrophic north Tasman Sea shows fractionation in the Cu isotopic signature in the photic zone but is relatively homogenised at depth. A minima in the Cu isotopic profile correlates with the chlorophyll a maximum at the site. These results indicate that a range of processes are likely to fractionate stable Cu isotopes in seawater.

  5. Natural isotope correction of MS/MS measurements for metabolomics and (13)C fluxomics.

    PubMed

    Niedenführ, Sebastian; ten Pierick, Angela; van Dam, Patricia T N; Suarez-Mendez, Camilo A; Nöh, Katharina; Wahl, S Aljoscha

    2016-05-01

    Fluxomics and metabolomics are crucial tools for metabolic engineering and biomedical analysis to determine the in vivo cellular state. Especially, the application of (13)C isotopes allows comprehensive insights into the functional operation of cellular metabolism. Compared to single MS, tandem mass spectrometry (MS/MS) provides more detailed and accurate measurements of the metabolite enrichment patterns (tandem mass isotopomers), increasing the accuracy of metabolite concentration measurements and metabolic flux estimation. MS-type data from isotope labeling experiments is biased by naturally occurring stable isotopes (C, H, N, O, etc.). In particular, GC-MS(/MS) requires derivatization for the usually non-volatile intracellular metabolites introducing additional natural isotopes leading to measurements that do not directly represent the carbon labeling distribution. To make full use of LC- and GC-MS/MS mass isotopomer measurements, the influence of natural isotopes has to be eliminated (corrected). Our correction approach is analyzed for the two most common applications; (13)C fluxomics and isotope dilution mass spectrometry (IDMS) based metabolomics. Natural isotopes can have an impact on the calculated flux distribution which strongly depends on the substrate labeling and the actual flux distribution. Second, we show that in IDMS based metabolomics natural isotopes lead to underestimated concentrations that can and should be corrected with a nonlinear calibration. Our simulations indicate that the correction for natural abundance in isotope based fluxomics and quantitative metabolomics is essential for correct data interpretation.

  6. Preliminary results of oxygen isotope ratio measurement with a particle-gamma coincidence method

    NASA Astrophysics Data System (ADS)

    Borysiuk, Maciek; Kristiansson, Per; Ros, Linus; Abdel, Nassem S.; Elfman, Mikael; Nilsson, Charlotta; Pallon, Jan

    2015-04-01

    The possibility to study variations in the oxygen isotopic ratio with photon tagged nuclear reaction analysis (pNRA) is evaluated in the current work. The experiment described in the article was performed at Lund Ion Beam Analysis Facility (LIBAF) with a 2 MeV deuteron beam. Isotopic fractionation of light elements such as carbon, oxygen and nitrogen is the basis of many analytical tools in hydrology, geology, paleobiology and paleogeology. IBA methods provide one possible tool for measurement of isotopic content. During this experimental run we focused on measurement of the oxygen isotopic ratio. The measurement of stable isotopes of oxygen has a number of applications; the particular one driving the current investigation belongs to the field of astrogeology and specifically evaluation of fossil extraterrestrial material. There are three stable isotopes of oxygen: 16O, 17O and 18O. We procured samples highly enriched with all three isotopes. Isotopes 16O and 18O were easily detected in the enriched samples, but no significant signal from 17O was detected in the same samples. The measured yield was too low to detect 18O in a sample with natural abundances of oxygen isotopes, at least in the current experimental setup, but the spectral line from the reaction with 16O was clearly visible.

  7. Isotopic Ratios in Titan's Methane: Measurements and Modeling

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Temelso, B.; Vinatier, S.; Teanby, N. A.; Bezard, B.; Achterberg, R. K.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G.; Jennings, D. E.; hide

    2012-01-01

    The existence of methane in Titan's atmosphere (approx. 6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of approx 20 Myr. In this paper, we examine the clues available from isotopic ratios (C-12/C-13 and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH4 collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: (13)CH4, (12)CH3D, and (13)CH3D. From these we compute estimates of C-12/C-13 = 86.5 +/- 8.2 and D/H = (1.59 +/- 0.33) x 10(exp -4) , in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH4 + C2H yields CH3 + C2H2. Using these new measurements and predictions we proceed to model the time evolution of C-12/C-13 and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH4), we find that the present-day C-12/C-13 implies that the CH4 entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing, We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane.

  8. ISOTOPIC RATIOS IN TITAN's METHANE: MEASUREMENTS AND MODELING

    SciTech Connect

    Nixon, C. A.; Achterberg, R. K.; Temelso, B.; Vinatier, S.; Bezard, B.; Coustenis, A.; Teanby, N. A.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G. J.; Jennings, D. E.; Romani, P. N.; Flasar, F. M.

    2012-04-20

    The existence of methane in Titan's atmosphere ({approx}6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of {approx}20 Myr. In this paper, we examine the clues available from isotopic ratios ({sup 12}C/{sup 13}C and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH{sub 4} collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: {sup 13}CH{sub 4}, {sup 12}CH{sub 3}D, and {sup 13}CH{sub 3}D. From these we compute estimates of {sup 12}C/{sup 13}C = 86.5 {+-} 8.2 and D/H = (1.59 {+-} 0.33) Multiplication-Sign 10{sup -4}, in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH{sub 4} + C{sub 2}H {yields} CH{sub 3} + C{sub 2}H{sub 2}. Using these new measurements and predictions we proceed to model the time evolution of {sup 12}C/{sup 13}C and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH{sub 4}), we find that the present-day {sup 12}C/{sup 13}C implies that the CH{sub 4} entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing. We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric

  9. Isotopic Ratios in Titan's Methane: Measurements and Modeling

    NASA Technical Reports Server (NTRS)

    Nixon, C. A.; Temelso, B.; Vinatier, S.; Teanby, N. A.; Bezard, B.; Achterberg, R. K.; Mandt, K. E.; Sherrill, C. D.; Irwin, P. G.; Jennings, D. E.; Romani, P. N.; Coustenis, A.; Flasar, F. M.

    2012-01-01

    The existence of methane in Titan's atmosphere (approx. 6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of approx 20 Myr. In this paper, we examine the clues available from isotopic ratios (C-12/C-13 and D/H) in Titan's methane as to the past atmosphere history of this species. We first analyze recent infrared spectra of CH4 collected by the Cassini Composite Infrared Spectrometer, measuring simultaneously for the first time the abundances of all three detected minor isotopologues: (13)CH4, (12)CH3D, and (13)CH3D. From these we compute estimates of C-12/C-13 = 86.5 +/- 8.2 and D/H = (1.59 +/- 0.33) x 10(exp -4) , in agreement with recent results from the Huygens GCMS and Cassini INMS instruments. We also use the transition state theory to estimate the fractionation that occurs in carbon and hydrogen during a critical reaction that plays a key role in the chemical depletion of Titan's methane: CH4 + C2H yields CH3 + C2H2. Using these new measurements and predictions we proceed to model the time evolution of C-12/C-13 and D/H in Titan's methane under several prototypical replenishment scenarios. In our Model 1 (no resupply of CH4), we find that the present-day C-12/C-13 implies that the CH4 entered the atmosphere 60-1600 Myr ago if methane is depleted by chemistry and photolysis alone, but much more recently-most likely less than 10 Myr ago-if hydrodynamic escape is also occurring. On the other hand, if methane has been continuously supplied at the replenishment rate then the isotopic ratios provide no constraints, and likewise for the case where atmospheric methane is increasing, We conclude by discussing how these findings may be combined with other evidence to constrain the overall history of the atmospheric methane.

  10. Isotopic composition of atmospheric moisture from pan water evaporation measurements.

    PubMed

    Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

    2015-01-01

    A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability.

  11. Single-Cell Growth Rates in Photoautotrophic Populations Measured by Stable Isotope Probing and Resonance Raman Microspectrometry

    PubMed Central

    Taylor, Gordon T.; Suter, Elizabeth A.; Li, Zhuo Q.; Chow, Stephanie; Stinton, Dallyce; Zaliznyak, Tatiana; Beaupré, Steven R.

    2017-01-01

    A new method to measure growth rates of individual photoautotrophic cells by combining stable isotope probing (SIP) and single-cell resonance Raman microspectrometry is introduced. This report explores optimal experimental design and the theoretical underpinnings for quantitative responses of Raman spectra to cellular isotopic composition. Resonance Raman spectra of isogenic cultures of the cyanobacterium, Synechococcus sp., grown in 13C-bicarbonate revealed linear covariance between wavenumber (cm−1) shifts in dominant carotenoid Raman peaks and a broad range of cellular 13C fractional isotopic abundance. Single-cell growth rates were calculated from spectra-derived isotopic content and empirical relationships. Growth rates among any 25 cells in a sample varied considerably; mean coefficient of variation, CV, was 29 ± 3% (σ/x¯), of which only ~2% was propagated analytical error. Instantaneous population growth rates measured independently by in vivo fluorescence also varied daily (CV ≈ 53%) and were statistically indistinguishable from single-cell growth rates at all but the lowest levels of cell labeling. SCRR censuses of mixtures prepared from Synechococcus sp. and T. pseudonana (a diatom) populations with varying 13C-content and growth rates closely approximated predicted spectral responses and fractional labeling of cells added to the sample. This approach enables direct microspectrometric interrogation of isotopically- and phylogenetically-labeled cells and detects as little as 3% changes in cellular fractional labeling. This is the first description of a non-destructive technique to measure single-cell photoautotrophic growth rates based on Raman spectroscopy and well-constrained assumptions, while requiring few ancillary measurements. PMID:28824580

  12. Long-Term Precipitation Isotope Ratios (δ18O, δ2H, d-excess) in the Northeast US Reflect Atlantic Ocean Warming and Shifts in Moisture Sources

    NASA Astrophysics Data System (ADS)

    Puntsag, T.; Welker, J. M.; Mitchell, M. J.; Klein, E. S.; Campbell, J. L.; Likens, G.

    2014-12-01

    The global water cycle is exhibiting dramatic changes as global temperatures increase resulting in increases in: drought extremes, flooding, alterations in storm track patterns with protracted winter storms, and greater precipitation variability. The mechanisms driving these changes can be difficult to assess, but the spatial and temporal patterns of precipitation water isotopes (δ18O, δ2H, d-excess) provide a means to help understand these water cycle changes. However, extended temporal records of isotope ratios in precipitation are infrequent, especially in the US. In our study we analyzed precipitation isotope ratio data from the Hubbard Brook Experimental Forest in New Hampshire that has the longest US precipitation isotope record, to determine: 1) the monthly composited averages and trends from 1967 to 2012 (45 years); ; 2) the relationships between abiotic properties such as local temperatures, precipitation type, storm tracks and isotope ratio changes; and 3) the influence of regional shifts in moisture sources and/or changes in N Atlantic Ocean water conditions on isotope values. The seasonal variability of Hubbard Brook precipitation isotope ratios is consistent with other studies, as average δ18O values are ~ -15‰ in January and ~ -5 ‰ in July. However, over the 45 year record there is a depletion trend in the δ 18O values (becoming isotopically lighter with a greater proportion of 16O), which coupled with less change in δ 2H leads to increases in d-excess values from ~ -10‰ around 1970 to greater than 10‰ in 2009. These changes occurred during a period of warming as opposed to cooling local temperatures indicating other processes besides temperature are controlling long-term water isotope traits in this region. We have evidence that these changes in precipitation isotope traits are controlled in large part by an increases in moisture being sourced from a warming N Atlantic Ocean that is providing evaporated, isotopically

  13. Heavy Atom Labeled Nucleotides for Measurement of Kinetic Isotope Effects

    PubMed Central

    Weissman, Benjamin P.; Li, Nan-Sheng; York, Darrin; Harris, Michael; Piccirilli, Joseph A.

    2015-01-01

    Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. Implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review we highlight current approaches to the synthesis of nucleic acids site-specifically enriched for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. PMID:25828952

  14. Heavy atom labeled nucleotides for measurement of kinetic isotope effects.

    PubMed

    Weissman, Benjamin P; Li, Nan-Sheng; York, Darrin; Harris, Michael; Piccirilli, Joseph A

    2015-11-01

    Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. The implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review, we highlight current approaches to the synthesis of nucleic acids enriched site specifically for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Measuring Light at Night and Melatonin Levels in Shift Workers: A Review of the Literature.

    PubMed

    Hunter, Claudia M; Figueiro, Mariana G

    2017-07-01

    Shift work, especially that involving rotating and night shifts, is associated with an increased risk of diseases, including cancer. Attempts to explain the association between shift work and cancer in particular have focused on the processes of melatonin production and suppression. One hypothesis postulates that exposure to light at night (LAN) suppresses melatonin, whose production is known to slow the development of cancerous cells, while another proposes that circadian disruption associated with shift work, and not just LAN, increases health risks. This review focuses on six studies that employed quantitative measurement of LAN and melatonin levels to assess cancer risks in shift workers. These studies were identified via searching the PubMed database for peer-reviewed, English-language articles examining the links between shift work, LAN, and disease using the terms light at night, circadian disruption, health, risk, cancer, shift work, or rotating shift. While the results indicate a growing consensus on the relationship between disease risks (particularly cancer) and circadian disruption associated with shift work, the establishment of a direct link between LAN and disease has been impeded by contradictory studies and a lack of consistent, quantitative methods for measuring LAN in the research to date. Better protocols for assessing personal LAN exposure are required, particularly those employing calibrated devices that measure and sample exposure to workplace light conditions, to accurately assess LAN's effects on the circadian system and disease. Other methodologies, such as measuring circadian disruption and melatonin levels in the field, may also help to resolve discrepancies in the findings.

  16. Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.

    2011-01-01

    One possible process responsible for methane generation on Mars is abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions. Measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane by tracing the geochemical pathway during formation. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible hydrogen isotope measurements. Reported here are results of experiments to characterize the hydrogen isotope composition of low molecular weight organic acids and alcohols. The presence of these organic compounds has been suggested by others as intermeadiary products made during mineral surface catalyzed reactions. This work compliments our previous study characterizing the carbon isotope composition of similar low molecular weight intermediary organic compounds (Socki, et al, American Geophysical Union Fall meeting, Abstr. #V51B-2189, Dec., 2010). Our hydrogen isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). Our technique is unique in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II? quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

  17. Prevention of fatigue and insomnia in shift workers-a review of non-pharmacological measures.

    PubMed

    Richter, Kneginja; Acker, Jens; Adam, Sophia; Niklewski, Guenter

    2016-01-01

    Excessive fatigue and insomnia are common among shift workers and can lead to negative effects such as reduced work performance, processing errors, accidents at work, absenteeism, reduced quality of life, and symptoms of depression. Moreover, work in rotating shifts can be a risk factor for different somatic and psychiatric diseases and may contribute to poor health, especially in elder adults and women. This review aims to show non-pharmacological preventive measures against fatigue and insomnia in shift workers. Computerized literature searches in MedLine and in the Cochrane Library were performed with the following key words: shift work disorder, fatigue, insomnia, shift work, measures, treatment, therapy, strategies and coping. The search was limited to non-pharmacological studies that were conducted on human subjects and published as English-language articles in peer-reviewed journals since 1970. Additional studies were identified through the reference sections of relevant articles. Eighteen articles on fatigue in shift workers, including six original research articles with a total sample size of 3504 probands consisting of industrial workers, office employees, aircraft maintenance engineers, and non-shift workers working in simulated shifts, were analyzed, as well as seven articles on insomnia, including an original research article with a sample size of 26 media workers. Also, 4 reviews on shift work disorder were analyzed. The occurrence of fatigue and insomnia in shift workers associated with a working period is described as shift work disorder. Estimations on the prevalence of shift work disorder in shift workers vary between 5 % and about 20 %; about one in three shift workers is affected by insomnia and up to 90 % of shift workers report regular fatigue and sleepiness at the workplace. We concluded that there is a necessity for treatments to improve the sleep quality of the shift working population. The most common non-pharmacological recommendations

  18. The Soil Carbon Paradigm Shift: Triangulating Theories, Measurements, and Models

    NASA Astrophysics Data System (ADS)

    Blankinship, J. C.; Crow, S. E.; Schimel, J.; Sierra, C. A.; Schaedel, C.; Plante, A. F.; Thompson, A.; Berhe, A. A.; Druhan, J. L.; Heckman, K. A.; Keiluweit, M.; Lawrence, C. R.; Marin-Spiotta, E.; Rasmussen, C.; Wagai, R.; Wieder, W. R.

    2016-12-01

    Predicting global responses of soil carbon (C) to environmental change remains confounded by a number of paradigms that have emerged from separate approaches. A prevailing paradigm in biogeochemistry interprets soil C as discrete pools based on estimated or measured turnover times (e.g., CENTURY model). An alternative is emerging that envisions the stabilization of soil C in tension between decomposition by microbial agents and protection by physical and chemical mechanisms. We propose an approach to bridge the gap between different paradigms, and to improve soil C forecasting by conceptualizing each paradigm as a triangle composed of three nodes: theory, analytical measurement, and numerical model. Paradigms tend to emerge from what can either be represented in models or measured using analytical instruments. But they gain power when all three elements are integrated in a balanced trinity. Our goal was to compare how theory, measurement, and model fit together in our understanding of soil C to learn from past successes, evaluate the strengths and weaknesses of current paradigms, and guide development of new understanding. We used a case-study approach to analyze each corner of the paradigm-triangle: i) paradigms that have strong theory but are constrained by weak linkages with measurements or models, ii) paradigms with robust models that have weak linkages with theory or measurements, and iii) paradigms with many measurements but little theoretical support or ability to be parameterized in numerical models. We conclude that established models like CENTURY dominate because theory and measurements that underlie the model form strong linkages that previously created a balanced triangle. Evolving paradigms based on physical protection and microbial agency are still struggling to gain traction because the theory is challenging to represent in models. The explicit examination of the strengths of emerging paradigms can, therefore, help refine and accelerate our ability

  19. Dual Si and O Isotope Measurement of Lunar Samples Using IRMS

    NASA Astrophysics Data System (ADS)

    Banerjee, N.; Hill, P. J. A.; Osinski, G. R.

    2016-12-01

    The use of isotopic systems and their associated theoretical models have become an increasingly sophisticated tool for investigating the origin of planetary bodies in the solar system. It was originally hypothesized that evidence for the impact origin of Moon would manifest itself as an isotopic heterogeneity between lunar and terrestrial samples; however, most isotope systems show no difference between the bulk Earth and Moon. The stable isotopes of both silicon (Si) and oxygen (O) have been essential in further understanding planetary processes including core formation. Historically the analysis of the Si and O isotope ratios in terrestrial and extraterrestrial material has primarily been measured independent of each other through three main techniques: isotope ratio mass spectrometry (IRMS), secondary ion mass spectrometry (SIMS), and multi-collector inductively coupled plasma mass-spectrometry (MC-ICPMS). Each technique has its own strength and weakness in regards to resolution and precision; however, one of the main limiting factors in all three of these techniques rests on the requirement of multiple aliquots. As most literature focuses on the measurement of oxygen or silicon isotopes, this unique line allows for the precise analysis of Si and O isotopes from the same aliquot of bulk sample, which cannot be done with SIMS or ICP-MS analysis. To deal with this problem a unique laser line system has been developed in the Laboratory for Stable Isotope Science at Western University, Canada, that simultaneously extracts SiF4 and O2 from the same 1-2 mg aliquot. We present the application of analyzing both isotopic systems from the sample aliquot to Apollo, meteoritic, and terrestrial samples and its implication for the formation of the Moon. Preliminary results from this line suggest that although the O isotopes ratios are consistent with a homogenous Moon-Earth system, a difference is observed in Si isotopes between Apollo and terrestrial samples compared to

  20. Nitrogen deposition to lakes in national parks of the western Great Lakes region: Isotopic signatures, watershed retention, and algal shifts

    NASA Astrophysics Data System (ADS)

    Hobbs, William O.; Lafrancois, Brenda Moraska; Stottlemyer, Robert; Toczydlowski, David; Engstrom, Daniel R.; Edlund, Mark B.; Almendinger, James E.; Strock, Kristin E.; VanderMeulen, David; Elias, Joan E.; Saros, Jasmine E.

    2016-03-01

    Atmospheric deposition is a primary source of reactive nitrogen (Nr) to undisturbed watersheds of the Great Lakes region of the U.S., raising concerns over whether enhanced delivery over recent decades has affected lake ecosystems. The National Atmospheric Deposition Program (NADP) has been measuring Nr deposition in this region for over 35 years. Here we explore the relationships among NADP-measured Nr deposition, nitrogen stable isotopes (δ15N) in lake sediments, and the response of algal communities in 28 lakes situated in national parks of the western Great Lakes region of the U.S. We find that 36% of the lakes preserve a sediment δ15N record that is statistically correlated with some form of Nr deposition (total dissolved inorganic N, nitrate, or ammonium). Furthermore, measured long-term (since 1982) nitrogen biogeochemistry and inferred critical nitrogen loads suggest that watershed nitrogen retention and climate strongly affect whether sediment δ15N is related to Nr deposition in lake sediment records. Measurements of algal change over the last ~ 150 years suggest that Nr deposition, in-lake nutrient cycling, and watershed inputs are important factors affecting diatom community composition, in addition to direct climatic effects on lake physical limnology. The findings suggest that bulk sediment δ15N does reflect Nr deposition in some instances. In addition, this study highlights the interactive effects of Nr deposition and climate variability.

  1. Comparative evaluation of quantitative glomerular filtration rate measured by isotopic and nonisotopic methods

    SciTech Connect

    Balachandran, S.; Toguri, A.G.; Petrusick, T.W.; Abbott, L.C.

    1981-04-01

    Good correlation of glomerular filtration rate measured isotopically from plasma disappearance of Tc-99m-DTPA was shown with inulin clearance, creatinine clearance, and graded radionuclide imaging. The isotopic GFR is a simple, urineless technique not requiring continuous infusion that enables one to perform simultaneous renal imaging with one radiotracer.

  2. Comparative evaluation of quantitative glomerular filtration rate measured by isotopic and nonisotopic methods

    SciTech Connect

    Balachandran, S.; Toguri, A.G.; Petrusick, T.W.; Abbott, L.C.

    1981-04-01

    Good correlation of glomerular filtration rate (GFR) measured isotopically from plasma disappearance of Tc-99m-DTPA (Sn) was shown with inulin clearance, creatinine clearance, and graded radionuclide imaging. The isotopic GFR is a simple, urineless technique not requiring continuous infusion that enables one to perform simultaneous renal imaging with one radiotracer.

  3. Direct Measurement of Biosphere-Atmosphere Isotopic Exchange Using the Eddy Covariance Technique

    USDA-ARS?s Scientific Manuscript database

    Quantifying isotopic CO2 exchange between the biosphere and atmosphere presents a significant measurement challenge, but has the potential to provide important constraints on local, regional, and global carbon cycling. Past approaches have indirectly estimated isotopic CO2 exchange using relaxed edd...

  4. A simple quantum statistical thermodynamics interpretation of an impressive phase diagram pressure shift upon (H/D) isotopic substitution in water + 3-methylpyridine.

    PubMed

    Visak, Zoran P; Szydlowski, Jerzy; Rebelo, Luís P N

    2006-01-26

    In a previous work (J. Phys. Chem. B 2003, 107, 9837), we reported liquid-liquid-phase splitting at negative pressures in mixtures of H2O + D2O + 3-methylpyridine (3-MP) at the limit of pure H2O as the solvent, thus extending for the first time the L-L phase diagrams to this metastable region. We showed that there is an intimate relation between pressure and solvent deuterium content. Isotopic substitution (H/D) in water provokes subtle entropic effects that, in turn, trigger a significant pressure shift, opening a pressure-wide miscibility window of as much as 1600 bar. Isotope effects are quantum in origin. Therefore, a model that is both pressure-dependent and considers quantization constitutes a necessary tool if one wishes to fully describe the p, T, x critical demixing in these systems. In the current work, the statistical-mechanical theory of isotope effects is combined with a compressible pressure-dependent model. This combination enabled us to predict successfully the overall L-L phase diagram via differences in the vibrational mode frequencies of water on its transfer from the pure state to that of dilution in 3-MP: each of the three librational modes undergo a calculated red-shift of -(250 +/- 30) cm(-1), while the overall internal frequencies contribution is estimated as a total +(400 +/- 25) cm(-1) blue-shift.

  5. Raman-shifted dye laser for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

    1987-01-01

    For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

  6. Raman-shifted dye laser for water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

    1987-01-01

    For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

  7. Shift and width measurements of the Stark-broadened ionized helium line at 1215 A

    NASA Technical Reports Server (NTRS)

    Van Zandt, J. R.; Adcock, J. C., Jr.; Griem, H. R.

    1976-01-01

    Time-resolved photoelectric measurements were made of the shifts of helium plasma lines at 1640 A and 1215 A and of the Stark profile of the 1215 A line, using an electromagnetic shock tube as a light source. These red shifts are consistent with a plasma polarization shift, where the interaction energy between the radiating ion and the perturbing plasma electrons corresponds to the Coulomb interaction near the excited state Bohr radius. No significant shifts were observed for the 1640 A line, while the 1215 A line underwent a red shift of about 0.5 A. The measured Stark width of the 1215 A line was 10-45% greater than the calculated width based on the measured width of the 4686 A line.

  8. Measuring the shift of a femtosecond laser frequency comb by the interference method

    SciTech Connect

    Basnak, Dmitriy V; Bikmukhametov, K A; Dmitriev, Aleksandr K; Dychkov, Aleksandr S; Kuznetsov, Sergei A; Lugovoy, A A; Mitsziti, P

    2012-01-31

    We have demonstrated the possibility of measuring the femtosecond laser frequency comb shift by the position of a Fabry - Perot interferometer's transmission bands with a statistical error of 10{sup -2} and a systematic shift of 10{sup -1}. (control of laser radiation parameters)

  9. Weak measurement of the composite Goos-Hänchen shift in the critical region

    NASA Astrophysics Data System (ADS)

    Santana, Octávio J. S.; Carvalho, Silvânia A.; De Leo, Stefano; de Araujo, Luís E. E.

    2016-08-01

    By using a weak measurement technique, we investigated the interplay between the angular and lateral Goos-Haenchen shift of a focused He-Ne laser beam for incidence near the critical angle. We verified that this interplay dramatically affects the composite Goos-Haenchen shift of the propagated beam. The experimental results confirm theoretical predictions that recently appeared in the literature.

  10. Sample matrix effects on measured carbon and oxygen isotope ratios during continuous-flow isotope-ratio mass spectrometry.

    PubMed

    Levitt, Nicholas Paul

    2014-11-15

    Continuous-flow isotope-ratio mass spectrometry (CF-IRMS) is frequently used to analyze CO2 found in media such as air, breath, and soil pore space gas with the aid of a sample preparation and transfer device such as a Gasbench II. This study investigated the effect that matrices other than helium (He) have on the measured δ(13)C and δ(18)O isotope ratios of CO2. Identical CO2 was added to sample vials with matrices of pure He, pure N2, or a 21:79 mixture of O2/N2 and analyzed by a ThermoFinnigan Delta(Plus) XP isotope-ratio mass spectrometer coupled to a ThermoFinnigan Gasbench II. Variables such as CO2 concentration, sample analysis sequence, and sample matrix removal ('blanking') through manipulation of an injection and dilution open split were tested to identify systematic isotope ratio offsets between the different matrix types. The process of blanking induced a δ(13)C and δ(18)O offset of ≤0.2‰ between otherwise identical populations of CO2 samples in He. The (13)C/(12)C and (18)O/(16)O isotope ratios of CO2 sampled from pure N2 or a mixture of O2/N2 were found to be within 0.1 to 0.2‰ of those of an identical CO2 sampled from a He matrix when N2 or O2/N2 was removed prior to transport to the mass spectrometer. The measured oxygen isotope ratios of CO2 sampled from N2 and O2/N2 varied by as much as 0.6‰ and 4‰, respectively, if matrix gas was not removed prior to ionization. Sampling CO2 from matrices similar to air does not significantly affect the measured (13)C/(12)C and (18)O/(16)O isotope ratios of CO2 when a gas-handling procedure that includes the removal of matrix gas is utilized. This procedure is much preferable to introducing matrix gas and potentially isobaric interference to the ion source. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Measurements of Forest-Atmosphere Isotopic CO2 Exchange by Eddy Covariance

    NASA Astrophysics Data System (ADS)

    Wehr, R. A.; Munger, J. W.; Nelson, D. D.; McManus, J. B.; Zahniser, M. S.; Saleska, S. R.

    2010-12-01

    Isotopic CO2 flux measurements are a promising means for partitioning the net ecosystem exchange of CO2 into photosynthetic and respiratory components. This approach to partitioning is possible in principle because of the distinct isotopic signatures of respired and photosynthesized CO2, but has been infeasible in practice—especially in forests—because of the difficulty of measuring isotopic ratios with sufficient precision and time response for use in eddy covariance (EC) flux calculations. Recent advances in laser spectroscopic instrumentation have changed that. We report measurements of isotopic (13C and 18O) CO2 exchange made by eddy covariance at Harvard Forest between April and December, 2010. The measurements were made using a continuous-wave quantum cascade laser spectrometer (Aerodyne Research Inc.) sampling at 4 Hz and are, to our knowledge, the first EC isotopic flux measurements at a forest site. The spectrometer can measure δ13C and δ18O with internal precisions (standard deviation of 1-minute averages) of 0.03 ‰, and [CO2] with an internal precision of 15 ppb; the instrumental accuracy, calibration, and long-term stability are discussed in detail. The isotopic data are considered in relation to environmental variables (PAR, temperature, humidity, soil temperature and moisture), and a first attempt at flux partitioning using the isotopic fluxes is presented.

  12. Measurements of tibial rotation during a simulated pivot shift manoeuvre using a gyroscopic sensor.

    PubMed

    Petrigliano, Frank A; Borgstrom, Per Henrik; Kaiser, William J; McAllister, David R; Markolf, Keith L

    2015-08-01

    The pivot shift has been correlated with patient-reported outcomes and knee function following ACL injury and reconstruction. Tibial rotation has been recognized as an important component to the pivot shift motion path. However, few methodologies exist to quantify tibial rotation in the clinical setting. The purpose of this study was to validate the use of a wireless gyroscopic sensor to measure axial rotation of the tibia during a manually simulated pivot shift manoeuvre in cadaveric specimens. We hypothesized that integrated gyroscopic measurements of tibial rotation velocity (tibial rotation) would be highly correlated with tibial rotations simultaneously recorded with a rotary potentiometer during a simulated pivot shift motion under intact and ACL-deficient conditions. Gyroscopic measurements of rotational velocity were integrated and calibrated to a known arc of rotation. The gyroscope was mounted on the distal tibia with its axis aligned to the tibial shaft. Ten simulations of a pivot shift motion pathway were performed on nine cadaveric knees under intact and ACL-deficient conditions. Logistic regression was used to compare gyroscopic and potentiometer measurements of tibial rotation for both test conditions. Gyroscopic measurements of maximum external tibial rotation during the simulated pivot shift motion pathway were strongly correlated with potentiometer measurements of external tibial rotation in both the intact and ACL-deficient states (R (2) = 0.984). The gyroscope evaluated in this cadaveric study was capable of accurately recording tibial rotation during a simulated pivot shift motion pathway.

  13. Stable Isotope Measurements of Carbon Dioxide, Methane, and Hydrogen Sulfide Gas Using Frequency Modulation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nowak-Lovato, K.

    2014-12-01

    Seepage from enhanced oil recovery, carbon storage, and natural gas sites can emit trace gases such as carbon dioxide, methane, and hydrogen sulfide. Trace gas emission at these locations demonstrate unique light stable isotope signatures that provide information to enable source identification of the material. Light stable isotope detection through surface monitoring, offers the ability to distinguish between trace gases emitted from sources such as, biological (fertilizers and wastes), mineral (coal or seams), or liquid organic systems (oil and gas reservoirs). To make light stable isotope measurements, we employ the ultra-sensitive technique, frequency modulation spectroscopy (FMS). FMS is an absorption technique with sensitivity enhancements approximately 100-1000x more than standard absorption spectroscopy with the advantage of providing stable isotope signature information. We have developed an integrated in situ (point source) system that measures carbon dioxide, methane and hydrogen sulfide with isotopic resolution and enhanced sensitivity. The in situ instrument involves the continuous collection of air and records the stable isotope ratio for the gas being detected. We have included in-line flask collection points to obtain gas samples for validation of isotopic concentrations using our in-house isotope ratio mass spectroscopy (IRMS). We present calibration curves for each species addressed above to demonstrate the sensitivity and accuracy of the system. We also show field deployment data demonstrating the capabilities of the system in making live dynamic measurements from an active source.

  14. Measurement of large /sup 19/F chemical shifts with the RYa-2305 spectrometer

    SciTech Connect

    Iorga, E.V.; Kucheryaev, A.G.; Lebedev, V.A.; Leont'eva, I.N.

    1985-06-01

    In order to extend the range of F-19 resonant frequencies in the RYa-2305 high-resolution NMR spectrometer, the authors have replaced the generator 9 by a tunable generator. This allows recording of the spectra together or to measure the chemical shifts exactly. The chemical shifts for MeF/sub 6/ in solutions of the hexafluorides of Mo, W, and U in organic solvents are shown, as measured at +20 degrees C. The upgrades in the RYa-2305 not only extend the range of measurable F-19 chemical shifts, but also enable one to measure large shifts with high accuracy. This principle for recording and measuring can be applied to other nuclides with the RYa2305 spectrometer.

  15. Associations between shift schedule characteristics with sleep, need for recovery, health and performance measures for regular (semi-)continuous 3-shift systems.

    PubMed

    van de Ven, Hardy A; Brouwer, Sandra; Koolhaas, Wendy; Goudswaard, Anneke; de Looze, Michiel P; Kecklund, Göran; Almansa, Josue; Bültmann, Ute; van der Klink, Jac J L

    2016-09-01

    In this cross-sectional study associations were examined between eight shift schedule characteristics with shift-specific sleep complaints and need for recovery and generic health and performance measures. It was hypothesized that shift schedule characteristics meeting ergonomic recommendations are associated with better sleep, need for recovery, health and performance. Questionnaire data were collected from 491 shift workers of 18 companies with 9 regular (semi)-continuous shift schedules. The shift schedule characteristics were analyzed separately and combined using multilevel linear regression models. The hypothesis was largely not confirmed. Relatively few associations were found, of which the majority was in the direction as expected. In particular early starts of morning shifts and many consecutive shifts seem to be avoided. The healthy worker effect, limited variation between included schedules and the cross-sectional design might explain the paucity of significant results.

  16. Direct phase-shift measurement with transmitted deep-UV illumination

    NASA Astrophysics Data System (ADS)

    Kusunose, Haruhiko; Awamura, Naoki; Takizawa, Hideo; Miyazaki, Kouji; Ode, Takahiro; Awamura, Daikichi

    1996-07-01

    This paper describes a direct phase-shift measurement system with transmitted deep-UV illumination for phase shifting mask (PSM) using a lateral shearing interferometer system. This interferometer has new structure developed for this purpose. The mirror mount of the interferometer is made of SiC ceramics that promote stability against vibration and ambient temperature drift. The illumination employs a xenon mercury arc lamp that has a spectrum close to the wavelength of KrF excimer laser. The repeatability of measurements is 0.5 degree in 3 sigma. The system can measure a small pattern down to 1 μm with an alternating type PSM with the objective of N.A.=0.4. Influence of incident angle of illumination on phase-shift measurement is investigated by experiment. The results show similar effects with simulation for circular illumination. The phase-shift measurement results on quartz step meet well with a calculation from step height and known refractive index including the effect of incident angle of illumination. The deep-UV measurement results also have good correlation with calculations from the results with another direct phase-shift measurement system that wavelength is 365nm. The simulation for focus latitude of alternating type PSMs agree with the experimental results of wafer exposure and the phase measurement. The accuracy of this system is sufficient for application to development of phase shift mask process.

  17. Oxygen Isotope Measurements of a Rare Murchison Type A CAI and Its Rim

    NASA Technical Reports Server (NTRS)

    Matzel, J. E. P.; Simon, J. I.; Hutcheon, I. D.; Jacobsen, B.; Simon, S. B.; Grossman, L.

    2013-01-01

    Ca-, Al-rich inclusions (CAIs) from CV chondrites commonly show oxygen isotope heterogeneity among different mineral phases within individual inclusions reflecting the complex history of CAIs in both the solar nebula and/or parent bodies. The degree of isotopic exchange is typically mineral-specific, yielding O-16-rich spinel, hibonite and pyroxene and O-16-depleted melilite and anorthite. Recent work demonstrated large and systematic variations in oxygen isotope composition within the margin and Wark-Lovering rim of an Allende Type A CAI. These variations suggest that some CV CAIs formed from several oxygen reservoirs and may reflect transport between distinct regions of the solar nebula or varying gas composition near the proto-Sun. Oxygen isotope compositions of CAIs from other, less-altered chondrites show less intra-CAI variability and 16O-rich compositions. The record of intra-CAI oxygen isotope variability in CM chondrites, which commonly show evidence for low-temperature aqueous alteration, is less clear, in part because the most common CAIs found in CM chondrites are mineralogically simple (hibonite +/- spinel or spinel +/- pyroxene) and are composed of minerals less susceptible to O-isotopic exchange. No measurements of the oxygen isotope compositions of rims on CAIs in CM chondrites have been reported. Here, we present oxygen isotope data from a rare, Type A CAI from the Murchison meteorite, MUM-1. The data were collected from melilite, hibonite, perovskite and spinel in a traverse into the interior of the CAI and from pyroxene, melilite, anorthite, and spinel in the Wark-Lovering rim. Our objectives were to (1) document any evidence for intra-CAI oxygen isotope variability; (2) determine the isotopic composition of the rim minerals and compare their composition(s) to the CAI interior; and (3) compare the MUM-1 data to oxygen isotope zoning profiles measured from CAIs in other chondrites.

  18. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the shock front advancing through the sample, thereby minimizing adverse effects of refraction.

  19. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, D.S.; Schmidt, S.C.

    1984-02-21

    A method is disclosed for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the stock front advancing through the sample, thereby minimizing adverse effects of refraction.

  20. Measurement of the Microwave Lensing shift in NIST-F1 and NIST-F2

    NASA Astrophysics Data System (ADS)

    Jefferts, S. R.; Heavner, T. P.; Barlow, S. E.; Ashby, N.

    2016-06-01

    With several Primary Frequency Standards (PFS) across the world demonstrating systematic fractional frequency uncertainties on order of 1 x 10-16, it is crucial to accurately measure or model even small frequency shifts that could affect the ultimate PFS uncertainty, and thus ultimately impact the rate of Coordinated Universal Time (UTC) which relies on precision PFS measurements. Recently there has been controversy about the physical causes and size of PFS frequency shifts due to microwave lensing effects. We present here the first measurements of microwave lensing frequency shifts in the PFS NIST-F1 and NIST-F2. The measured frequency shifts agree well with the recent theory of Ashby et al [1].

  1. Experimental measurement of boron isotope fractionation in seawater

    NASA Astrophysics Data System (ADS)

    Klochko, Kateryna; Kaufman, Alan J.; Yao, Wengsheng; Byrne, Robert H.; Tossell, John A.

    2006-08-01

    The boron isotopic composition of marine carbonates is considered to be a tracer of seawater pH. Use of this proxy benefits from an intimate understanding of chemical kinetics and thermodynamic isotope exchange reactions between the two dominant boron-bearing species in seawater: boric acid B(OH) 3 and borate ion B(OH) 4-. However, because of our inability to quantitatively separate these species in solution, the degree of boron isotope exchange has only been known through theoretical estimates. In this study, we present results of a spectrophotometric procedure wherein the boron isotope equilibrium constant ( 11-10KB) is determined empirically from the difference in the dissociation constants of 11B(OH) 3 and 10B(OH) 3 in pure water, 0.6 mol kg - 1 H 2O KCl and artificial seawater. Within experimental uncertainty, our results show no dependence of 11-10KB on temperature, but 11-10KB at 25 °C in pure water was statistically different than results obtained in solutions at high ionic strength. 11-10KB of the seawater ( S = 35, B T = 0.01 mol kg - 1 H 2O) at 25 °C is 1.0272 ± 0.0006. This result is significantly larger than the theoretical value used in numerous paleo-pH studies ( 11-10KB = 1.0194).

  2. Using cosmogenic isotopes to measure basin-scale rates of erosion

    SciTech Connect

    Bierman, P.R.; Steig, E. . Dept. of Geology)

    1992-01-01

    The authors present a new and different approach to interpreting the abundance of in situ-produced cosmogenic nuclides such as [sup 36]Cl, [sup 26]Al, and [sup 10]Be. Unlike most existing models, which are appropriate for evaluating isotope concentrations on bedrock surfaces, this model can be used to interpret isotope concentration in fluvial sediment. Because sediment is a mixture of material derived from the entire drainage basin, measured isotope abundances can be used to estimate spatially-averaged rates of erosion and sediment transport. Their approach has the potential to provide geomorphologists with a relatively simple but powerful means by which to constrain rates of landscape evolution. The model considers the flux of cosmogenic isotopes into and out of various reservoirs. Implicit in model development are the assumptions that a geomorphic steady-state has been reached and that sampled sediment is spatially and temporally representative of all sediment leaving the basin. Each year, the impinging cosmic-ray flux produces a certain quantity of cosmogenic isotopes in the rock and soil of a drainage basin. For a basin in steady state, the outgoing isotope flux is also constant. They solve for the rate of mass loss as a function of isotope abundance in the sediment, the cosmic ray attenuation length, the isotope half life, and the effective isotope production rate. There are only a few published measurements of cosmogenic isotope abundance in sediment. They calculated model denudation rates for sediment samples from Zaire and central Texas. The denudation rates they calculated appear reasonable and are similar to those they have measured directly on granite landforms in Georgia and southeastern California and those calculated for the Appalachian Piedmont.

  3. Measurement scheme for the Lamb shift in a superconducting circuit with broadband environment

    SciTech Connect

    Gramich, V.; Ankerhold, J.; Solinas, P.; Moettoenen, M.; Pekola, J. P.

    2011-11-15

    Motivated by recent experiments on quantum mechanical charge pumping in a Cooper pair sluice, we present a measurement scheme for observing shifts of transition frequencies in two-level quantum systems induced by broadband environmental fluctuations. In contrast to quantum optical and related setups based on cavities, the impact of a thermal phase reservoir is considered. A thorough analysis of Lamb and Stark shifts within weak-coupling master equations is complemented by nonperturbative results for the model of an exactly solvable harmonic system. The experimental protocol to measure the Lamb shift in experimentally feasible superconducting circuits is analyzed in detail and supported by numerical simulations.

  4. Precision excited-state lifetime measurements of neutron-rich Li isotopes

    NASA Astrophysics Data System (ADS)

    Morse, C.; Lister, C. J.; Wilson, G. L.; McCutchan, E. A.; Hackman, G.; Bowry, M.; Caballero-Folch, R.; Evitts, L. J.; Garnsworthy, A. B.; Henderson, J.; Kurkjian, A.; Measures, J. P.; Moukaddam, M.; Ruotsalainen, P.; Smallcombe, J.; Smith, J. K.; Southall, D.; Williams, M.; Mitchell, A. J.; Wu, C. Y.

    2016-09-01

    Recent successes with ab initio calculations are allowing increasingly subtle nuclear phenomena to be investigated, such as Δ-isobar and meson exchange effects which are necessary to reproduce M 1 properties of nuclei. In order to guide such explorations, precise experimental data are required to discriminate between various theoretical descriptions. The lithium isotopes, which are dominated by M 1 spin-flip transitions, provide an ideal testing ground for such studies. We have performed lifetime measurements of the excited states of 7,8Li, as well as explored the feasibility of such an experiment on 9Li, to provide precise data on the M 1 transition matrix elements in these nuclei. The experiment used the Doppler Shift Attenuation Method to measure the lifetimes at TRIUMF with TIGRESS, with the excited states populated by inverse (d , p) reactions. Preliminary results from the analysis will be presented. This research was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Grants DE-FG02-94ER40848.

  5. Mass measurements on radioactive isotopes with a Penning trap mass spectrometer

    SciTech Connect

    Bollen, G.; Ames, F.; Schark, E.; Audi, G.; Lunney, D.; Saint Simon, M. de; Beck, D.; Herfurth, F.; Kluge, H.-J.; Kohl, A.; Schwarz, S.; Moore, R. B.; Szerypo, J.

    1999-01-15

    Penning trap mass measurements on short-lived isotopes are performed with the ISOLTRAP mass spectrometer at the radioactive beam facility ISOLDE/CERN. In the last years the applicability of the spectrometer has been considerably extended by the installation of an RFQ trap ion beam buncher and a new cooler Penning trap, which is operated as an isobar separator. These improvements allowed for the first time measurements on isotopes of rare earth elements and on isotopes with Z=80-85. In all cases an accuracy of {delta}m/m{approx_equal}1{center_dot}10{sup -7} was achieved.

  6. New Oxygen Isotope Measurements of Four Stardust Impact Crater Residues Show IDP-Like Compositions

    NASA Astrophysics Data System (ADS)

    Snead, C. J.; McKeegan, K. D.

    2015-07-01

    We have measured the oxygen isotope compositions of four Stardust impact crater residues. These analyses reveal compositions that are similar to those found in interplanetary dust particles, antarctic micrometeorites and CI chondrite components.

  7. Control study on Evapotranspiration partitioning for grassland through on-situ isotopic measurement

    NASA Astrophysics Data System (ADS)

    Sun, X.; Wilcox, B. P.; Zou, C.; Stebler, E.; West, J. B.

    2016-12-01

    Isotopic composition of water varies in different pools and fluxes along the hydrologic flow. This variation between evaporation and transpiration also enable isotope as indispensable tracer to partition these two different evapotranspiration components. Our control experiment was applied to two grassland sites, of which herbicide (roundup) was carried out as control. We took continuous In-situ measurement of deuterium and oxygen-18 at high-temporal resolution with a cavity ring-down spectroscopy water vapor isotope analyzer. Root and leaf was sampled at sub-daily level under non-steady theory for transpiration. Soil water was also taken to obtain isotopic value for soil evaporation with Craig-Gordon model. The relative contribution of transpiration to evaporation will cross-checked by isotopic partitioning and control site. So the robustness of current theory of evapotranspiration partitioning under natural ecosystems will be examined and improved.

  8. Isotope abundances of solar coronal material derived from solar energetic particle measurements

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Stone, E. C.

    1989-01-01

    Coronal isotopic abundances for the elements He, C, N, O, Ne, and Mg are derived from previously published measurements of the isotopic composition of solar energetic particles by first measuring, and then correcting for, the charge-to-mass-dependent fractionation due to solar flare acceleration and propagation processes. The resulting coronal composition generally agrees with that of other samples of solar system material, but the previously noted difference between the solar flare and solar wind Ne-22/Ne-20 ratios remains unresolved.

  9. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    USDA-ARS?s Scientific Manuscript database

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  10. 13C isotope effects on 1H chemical shifts: NMR spectral analysis of 13C-labelled D-glucose and some 13C-labelled amino acids.

    PubMed

    Tiainen, Mika; Maaheimo, Hannu; Soininen, Pasi; Laatikainen, Reino

    2010-02-01

    The one- and two-bond (13)C isotope shifts, typically -1.5 to -2.5 ppb and -0.7 ppb respectively, in non-cyclic aliphatic systems and up to -4.4 ppb and -1.0 ppb in glucose cause effects that need to be taken into account in the adaptive NMR spectral library-based quantification of the isotopomer mixtures. In this work, NMR spectral analyses of some (13)C-labelled amino acids, D-glucose and other small compounds were performed in order to obtain rules for prediction of the (13)C isotope effects on (1)H chemical shifts. It is proposed that using the additivity rules, the isotope effects can be predicted with a sufficient accuracy for amino acid isotopomer applications. For glucose the effects were found strongly non-additive. The complete spectral analysis of fully (13)C-labelled D-glucose made it also possible to assign the exocyclic proton signals of the glucose. Copyright 2009 John Wiley & Sons, Ltd.

  11. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    SciTech Connect

    Couture, A.; Bond, E.; Bredeweg, T. A.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Agvaanluvsan, U.; Becker, J. A.; Baker, J. D.; Bayarbadrahk, B.; Chyzh, A.; Dashdorj, D.; Reifarth, R.

    2009-03-10

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-{pi}BaF{sub 2} scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  12. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    NASA Astrophysics Data System (ADS)

    Couture, A.; Agvaanluvsan, U.; Baker, J. D.; Bayarbadrahk, B.; Becker, J. A.; Bond, E.; Bredeweg, T. A.; Chyzh, A.; Dashdorj, D.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.

    2009-03-01

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-π BaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  13. High Precision Ti stable Isotope Measurement of Terrestrial Rocks

    NASA Astrophysics Data System (ADS)

    Millet, M. A.; Dauphas, N.; Williams, H. M.; Burton, K. W.; Nowell, G. M.

    2014-12-01

    Advances in multi-collection plasma source mass spectrometry have allowed the determination of stable isotope composition of transition metals to address questions relevant to both high and low temperature geochemistry. However, titanium has received only very limited attention. Here we present a new technique allowing the determination of the stable isotope composition of titanium in geological samples (d49Ti or deviation of the 49Ti/47Ti ratio from the OL-Ti in-house standard of reference) using double-spike methodology and high-resolution MC-ICP-MS. We have carried out a range analytical tests for a wide spectrum of samples matrices to demonstrate a external reproducibility of ±0.02‰ on the d49Ti while using as little as 150ng of natural Ti for a single analysis. We have analysed a comprehensive selection of mantle-derived samples covering a range of geodynamic contexts (MORB, IAB, OIB, adakites, eclogites, serpentines) and geographical distribution (MORB: Mid-Atlantic Ridge, Southwest Indian Ridge and Eastern Pacific Ridge; IAB: New Britain reference suite and Marianas Arc). The samples show a very limited range from -0.06‰ to +0.04‰ with a main mode at +0.004‰ relative to the OL-Ti standard. Average values for MORB, IAB and eclogites are similar within uncertainty and thus argue for limited mobility of Ti during subduction zone processes and homogeneity of the Ti stable isotope composition of the upper mantle. However, preliminary data for more evolved igneous rocks suggest that they display heavier Ti stable isotope compositions, which may reflect the removal of isotopically light Ti as a function of Fe-Ti oxide crystallisation. This is in good agreement with Ti being present in 5-fold and 6-fold coordination in basaltic melts and preferential uptake of 6-folded Ti by Ti-bearing oxides [1]. This dataset will be complemented by analysis of abyssal peridotites to confirm the homogeneity of the mantle as well as data for a range of ferromanganese crusts

  14. Stable water isotope and surface heat flux simulation using ISOLSM: Evaluation against in-situ measurements

    NASA Astrophysics Data System (ADS)

    Cai, Mick Y.; Wang, Lixin; Parkes, Stephen D.; Strauss, Josiah; McCabe, Matthew F.; Evans, Jason P.; Griffiths, Alan D.

    2015-04-01

    The stable isotopes of water are useful tracers of water sources and hydrological processes. Stable water isotope-enabled land surface modeling is a relatively new approach for characterizing the hydrological cycle, providing spatial and temporal variability for a number of hydrological processes. At the land surface, the integration of stable water isotopes with other meteorological measurements can assist in constraining surface heat flux estimates and discriminate between evaporation (E) and transpiration (T). However, research in this area has traditionally been limited by a lack of continuous in-situ isotopic observations. Here, the National Centre for Atmospheric Research stable isotope-enabled Land Surface Model (ISOLSM) is used to simulate the water and energy fluxes and stable water isotope variations. The model was run for a period of one month with meteorological data collected from a coastal sub-tropical site near Sydney, Australia. The modeled energy fluxes (latent heat and sensible heat) agreed reasonably well with eddy covariance observations, indicating that ISOLSM has the capacity to reproduce observed flux behavior. Comparison of modeled isotopic compositions of evapotranspiration (ET) against in-situ Fourier Transform Infrared spectroscopy (FTIR) measured bulk water vapor isotopic data (10 m above the ground), however, showed differences in magnitude and temporal patterns. The disparity is due to a small contribution from local ET fluxes to atmospheric boundary layer water vapor (∼1% based on calculations using ideal gas law) relative to that advected from the ocean for this particular site. Using ISOLSM simulation, the ET was partitioned into E and T with 70% being T. We also identified that soil water from different soil layers affected T and E differently based on the simulated soil isotopic patterns, which reflects the internal working of ISOLSM. These results highlighted the capacity of using the isotope-enabled models to discriminate

  15. Isotopic evidence for shifts in atmospheric circulation patterns during the late Quaternary in mid-North America

    USGS Publications Warehouse

    Amundson, Ronald; Chadwick, O.; Kendall, C.; Wang, Y.; DeNiro, M.

    1996-01-01

    Wyoming is now at the eastern margin of westerlies originating in the Pacific, but in the Pleistocene appears to have received moisture from elsewhere, possibly the Gulf of Mexico. Oxygen isotope ratios of pedogenic carbonate in postglacial terraces correspond to ratios in equilibrium with present meteoric waters, which show a strong relation to precipitation seasonality and storm sources. In contrast, the oxygen isotope rations of all pre-Holocene soils are significantly more positive, even though the carbon isotope composition of coexisting organic matter suggests that the carbonate formed in temperatures cooler than today. The oxygen isotope rations of paleowaters in mid-North America appear to be more useful for identifying past storm sources than for estimating paleotemperatures.

  16. Carbon isotopic shift and its cause at the Wuchiapingian-Changhsingian boundary in the Upper Permian at the Zhaojiaba section, South China: Evidences from multiple geochemical proxies

    NASA Astrophysics Data System (ADS)

    Wei, Hengye; Yu, Hao; Wang, Jianguo; Qiu, Zhen; Xiang, Lei; Shi, Guo

    2015-06-01

    The Late Permian environmental change, connecting the Guadalupian-Lopingian (G-L) (Middle-Upper Permian) boundary mass extinction and the Permain-Triassic (P-Tr) boundary mass extinction, has attracted more and more attentions. A significant negative shift for carbon isotope had been found at the Wuchiapingian-Changhsingian (W-C) boundary in the Upper Permian recently. However, the cause(s) of this negative excursion is still unknown. To resolve this problem, we analyzed the bulk organic carbon isotope, total organic carbon (TOC) content, pyritic sulfur (Spy) content, major element concentrations, and molecular organic biomarkers in the Wujiaping and Dalong formations in the Upper Permian from the Zhaojiaba section in western Hubei province, South China. Our results show that (1) there was a significant negative excursion in organic carbon isotopes at the W-C boundary and again a negative excursion at the top of Changhsingian stage; (2) the significant negative excursion at the W-C boundary was probably a global signal and mainly caused by the low primary productivity; and (3) the negative carbon isotope excursion at the top of Changhsingian was probably caused by the Siberian Traps eruptions. A decline in oceanic primary productivity at the W-C boundary probably represents a disturbance of the marine food web, leading to a vulnerable ecosystem prior to the P-Tr boundary mass extinction.

  17. Hydrological and Vegetation Shifts in the Equatorial Sulawesi since the Last Glacial Maximum: Perspectives from Hydrogen and Carbon Isotopes of Terrestrial Leaf Wax Compounds

    NASA Astrophysics Data System (ADS)

    Wicaksono, Satrio; Russell, James; Holbourn, Ann; Kuhnt, Wolfgang

    2014-05-01

    The Indo-Pacific Warm Pool (IPWP) is a major epicenter of the tropical convective activity that drives both the Walker and Hadley circulations. The island of Sulawesi is situated at the heart of the Maritime Continent within the IPWP, and despite the region's importance, published proxy records and numerical simulations of convection and precipitation patterns from Sulawesi and across the Maritime Continent since the Last Glacial Maximum (LGM) display some substantial disagreement. Today, precipitation over Sulawesi is strongly influenced by variations in topography and wind pattern, which include land-sea breezes, orographically-forced winds, and monsoonal winds related to the seasonal migration of the Intertropical Convergence Zone. To better understand the interplay between such variations and high latitude climate dynamics during the last deglaciation, we developed high resolution records of the deuterium isotopic composition of terrestrial leaf waxes (long-chain n-alkanoic acids; δDwax) from a marine core (3.63 ºS, 119.36 ºE, water depth: 688 m) retrieved 10 km west of Sulawesi in close proximity to a major river delta. At low latitudes, δDwax has been used to reconstruct the δD of catchment-integrated precipitation, often interpreted as an indicator of regional rainfall amounts and large-scale convective activity. Our record displays relatively depleted values during the height of LGM, followed by a gradual enrichment that reached its peak (up to 10o enrichment) during the Younger Dryas (YD). Following the YD, δDwax becomes more depleted into the Holocene, reaching values nearly identical to the LGM. The deglacial pattern observed in our δDwax, derived from a predominantly high-altitude catchment in the southwestern arm of Sulawesi, is similar to that of δDwax record from Lake Towuti (2.5 ºS, 121.5 ºE, surface elevation: 319 m) in the southeastern arm of Sulawesi. The synoptic deglacial shifts seen in both catchments demonstrate that the equatorial

  18. A liquid chromatography - mass spectrometry method to measure ¹³C-isotope enrichment for DNA stable-isotope probing.

    PubMed

    Auclair, Julie; Lépine, François; Villemur, Richard

    2012-03-01

    DNA stable-isotope probing (DNA-SIP) is a cultivation-independent technique that makes it possible to associate metabolic function and taxonomic identity in a wide range of terrestrial and aquatic environments. In DNA-SIP, DNA is labeled via the assimilation of a labeled growth substrate that is subsequently used to identify microorganisms involved in assimilation of the substrate. However, the labeling time has to be sufficient to obtain labeled DNA but not so long such that cross-feeding of ¹³C-labeled metabolites from the primary consumers to nontarget species can occur. Confirmation that the DNA is isotopically labeled in DNA-SIP assays can be achieved using an isotope ratio mass spectrometer. In this study, we describe the development of a method using liquid chromatography (HPLC) coupled to a quadrupole mass spectrometer (QMS) to measure the ¹³C enrichment of thymine incorporated into DNA in Escherichia coli cultures fed with [¹³C]acetate. The method involved the hydrolysis of DNA extracted from the cultures that released the nucleotides, followed by the separation of the thymine by HPLC on a reverse-phase C₈ column in isocratic elution mode and the detection and quantification of ¹³C-labeled thymine by QMS. To mimic a DNA-SIP assay, a DNA mixture was made using ¹³C-labeled E. coli DNA with DNA extracted from five bacterial species. The HPLC-MS method was able to measure the correct proportion of ¹³C-DNA in the mix. This method can then be used as an alternative to the use of isotope ratio mass spectrometry in DNA-SIP assays.

  19. A direct measurement of the stable isotopes of transpired water vapor in a northern Michigan forest

    NASA Astrophysics Data System (ADS)

    Aron, P.; Poulsen, C. J.; Fiorella, R.

    2016-12-01

    The stable isotopes of oxygen and hydrogen in water vapor track hydrologic processes as phase changes of water preferentially partition heavy isotopes (18O and 2H) into the condensate and light isotopes (16O and 1H) into the vapor phase. As a result, the isotopic composition of water vapor can be used to identify water fluxes and cycling through natural environments. Forest water vapor is comprised of terrestrial (evaporation and transpiration) and atmospheric (tropospheric mixing, precipitation, and condensation) components. Within the isotopic record of forest water vapor, stable isotopes of transpired water (δT) comprise an important component but is typically either assumed to be non-fractionating or estimated indirectly. However, on small time scales (minutes to hours), non-steady state forest systems experience isotopic enrichment during early morning and late afternoon when transpiration rates are low. We deployed two Picarro Cavity Ring-Down spectrometers (L2120-i and L2130-i, respectively) in the University of Michigan Biological Station (UMBS) forest near Pellston, MI to measure the isotopic composition of near-surface ambient water vapor and the transpired vapor component directly. Both ambient and transpired water vapor were measured at three heights above the forest floor (2, 10, and 20 m) during August 2016. To measure species-specific water use, δT was measured on red maple (Acer rubrum) and northern red oak (Quercus rubra), two of the dominant tree types in the UMBS forest. This work represents the first direct measurement of δT in the UMBS forest and will help decouple local and species-specific hydrologic cycling. Beyond UMBS, this measurement will allow for a better understanding of species-specific plant hydraulics and help identify when the steady state approximation of transpiration is valid, which can be used to study water use and forest health.

  20. Dynamic Phase Shifts in Nanoscale Distance Measurements by Double Electron Electron Resonance (DEER)†

    SciTech Connect

    Bowman, Michael K.; Maryasov, Alexander G.

    2007-04-01

    The off-resonant pump pulse used in double electron electron resonance (DEER) measurements produces dynamic phase shifts that are explained here by simple analytic and vector descriptions of the full range of signal behaviors observed during DEER measurements, including: large phase shifts in the signal; changes in the position and shape of the detected echo; and changes in the signal intensity. The dynamic phase shifts depend on the width, amplitude and offset frequency of the pump pulse. Isolated radicals as well as pairs or clusters of dipolar-coupled radicals have the same dynamic phase shift that is independent of pump pulse delay in a typical measurement. A method of calibrating both the pump pulse offset frequency and the pump pulse field strength is outlined. A vector model is presented that explains the dynamic phase shifts in terms of precessing magnetization that is either spin locked or precessing about the effective pump field during the pump pulse. Implications of the dynamic phase shifts are discussed as they relate to setting up, calibrating and interpreting the results of DEER measurements.

  1. Dynamic phase shifts in nanoscale distance measurements by double electron electron resonance (DEER)

    NASA Astrophysics Data System (ADS)

    Bowman, Michael K.; Maryasov, Alexander G.

    2007-04-01

    The off-resonant pump pulse used in double electron electron resonance (DEER) measurements produces dynamic phase shifts that are explained here by simple analytic and vector descriptions of the full range of signal behaviors observed during DEER measurements, including: large phase shifts in the signal; changes in the position and shape of the detected echo; and changes in the signal intensity. The dynamic phase shifts depend on the width, amplitude and offset frequency of the pump pulse. Isolated radicals as well as pairs or clusters of dipolar-coupled radicals have the same dynamic phase shift that is independent of pump pulse delay in a typical measurement. A method of calibrating both the pump pulse offset frequency and the pump pulse field strength is outlined. A vector model is presented that explains the dynamic phase shifts in terms of precessing magnetization that is either spin locked or precessing about the effective pump field during the pump pulse. Implications of the dynamic phase shifts are discussed as they relate to setting up, calibrating and interpreting the results of DEER measurements.

  2. Optimized weak measurements of Goos-Hänchen and Imbert-Fedorov shifts in partial reflection.

    PubMed

    Goswami, S; Dhara, S; Pal, M; Nandi, A; Panigrahi, P K; Ghosh, N

    2016-03-21

    The spatial and the angular variants of the Imbert-Federov (IF) beam shifts and the angular Goos-Hänchen (GH) shift contribute in a complex interrelated way to the resultant beam shift in partial reflection at planar dielectric interfaces. Here, we show that the two variants of the IF effects can be decoupled and separately observed by weak value amplification and subsequent conversion of spatial ↔angular nature of the beam shifts using appropriate pre and post selection of polarization states. Such optimized weak measurement schemes also enable one to nullify one effect (either the GH or the IF) and exclusively observe the other. We experimentally demonstrate this and illustrate various other intriguing manifestations of optimized weak measurements in elliptical and / or linear polarization basis. We also present a Poincare sphere based analysis on conversion / retention of the angular or spatial nature of the shifts with pre and post selection of states in weak measurement. The demonstrated ability to amplify, controllably decouple or combine the beam shifts via weak measurements may prove to be valuable for understanding the different physical contributions of the effects and for their applications in sensing and precision metrology.

  3. Weak measurement of the composite Goos-Hänchen shift in the critical region.

    PubMed

    Santana, Octávio J S; Carvalho, Silvânia A; De Leo, Stefano; de Araujo, Luís E E

    2016-08-15

    By using a weak measurement technique, we investigated the interplay between the angular and the lateral Goos-Hänchen shift of a focused He-Ne laser beam for incidence near the critical angle. We verified that this interplay dramatically affects the composite Goos-Hänchen shift of the propagated beam. The experimental results confirm theoretical predictions that recently appeared in the literature.

  4. MEASUREMENTS OF COSMIC-RAY HYDROGEN AND HELIUM ISOTOPES WITH THE PAMELA EXPERIMENT

    SciTech Connect

    Adriani, O.; Bongi, M.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Bruno, A.; Boezio, M.; Bonvicini, V.; Formato, V.; Bogomolov, E. A.; Bottai, S.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Santis, C. De; Castellini, G.; Donato, C. De; Simone, N. De; Felice, V. Di; and others

    2016-02-10

    The cosmic-ray hydrogen and helium ({sup 1}H, {sup 2}H, {sup 3}He, {sup 4}He) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on board the Resurs-DK1 satellite on 2006 June 15. The rare isotopes {sup 2}H and {sup 3}He in cosmic rays are believed to originate mainly from the interaction of high-energy protons and helium with the galactic interstellar medium. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from 2006 July to 2007 December.

  5. Measurements of Cosmic-Ray Hydrogen and Helium Isotopes with the PAMELA Experiment

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; De Donato, C.; De Santis, C.; De Simone, N.; Di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergè, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.

    2016-02-01

    The cosmic-ray hydrogen and helium (1H, 2H, 3He, 4He) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on board the Resurs-DK1 satellite on 2006 June 15. The rare isotopes 2H and 3He in cosmic rays are believed to originate mainly from the interaction of high-energy protons and helium with the galactic interstellar medium. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from 2006 July to 2007 December.

  6. High-speed phase-shifting interferometry using triangular prism for time-resolved temperature measurement.

    PubMed

    Shoji, Eita; Komiya, Atsuki; Okajima, Junnosuke; Kawamura, Hiroshi; Maruyama, Shigenao

    2015-07-10

    This study proposes a high-speed phase-shifting interferometer with an original optical prism. This phase-shifting interferometer consists of a polarizing Mach-Zehnder interferometer, an original optical prism, a high-speed camera, and an image-processing unit for a three-step phase-shifting technique. The key aspect of the application of the phase-shifting technique to high-speed experiments is an original prism, which is designed and developed specifically for a high-speed phase-shifting technique. The arbaa prism splits an incident beam into four output beams with different information. The interferometer was applied for quantitative visualization of transient heat transfer. In order to test the optical system for measuring high-speed phenomena, the temperature during heat conduction was measured around a heated thin tungsten wire (diameter of 5 μm) in water. The visualization area is approximately 90  μm×210  μm, and the spatial resolution is 3.5 μm at 300,000 fps of the maximum temporal resolution with a high-speed camera. The temperature fields around the heated wire were determined by converting phase-shifted data using the inverse Abel transform. Finally, the measured temperature distribution was compared with numerical calculations to validate the proposed system; a good agreement was obtained.

  7. Accurate measurement of silver isotopic compositions in geological materials including low Pd/Ag meteorites

    NASA Astrophysics Data System (ADS)

    Woodland, S. J.; Rehkämper, M.; Halliday, A. N.; Lee, D.-C.; Hattendorf, B.; Günther, D.

    2005-04-01

    Very precise silver (Ag) isotopic compositions have been determined for a number of terrestrial rocks, and high and low Pd/Ag meteorites by utilizing multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The meteorites include primitive chondrites, the Group IAB iron meteorites Canyon Diablo and Toluca, and the Group IIIAB iron meteorite Grant. Silver isotopic measurements are primarily of interest because 107Ag was produced by decay of the short-lived radionuclide 107Pd during the formation of the solar system and hence the Pd-Ag chronometer has set constraints on the timing of early planetesimal formation. A 2σ precision of ±0.05‰ can be obtained for analyses of standard solutions when Ag isotopic ratios are normalized to Pd, to correct for instrumental mass discrimination, and to bracketing standards. Caution must be exercised when making Ag isotopic measurements because isotopic artifacts can be generated in the laboratory and during mass spectrometry. The external reproducibility for geological samples based on replicate analyses of rocks is ±0.2‰ (2σ). All chondrites analyzed have similar Ag isotopic compositions that do not differ significantly (>0.3‰) from the 'terrestrial' value of the NIST SRM 978a Ag isotope standard. Hence, they show no evidence of excess 107Ag derived from 107Pd decay or, of stable Ag isotope fractionation associated with volatile element depletion within the accretion disk or from parent body metamorphism. The Group IAB iron meteorite samples analyzed show evidence of complex behavior and disturbance of Ag isotope systematics. Therefore, care must be taken when using this group of iron meteorites to obtain chronological information based on the Pd-Ag decay scheme.

  8. Feasibility of stimulated emission to measure {ital R}-line shifts in shock compressed ruby

    SciTech Connect

    Knudson, M.D.; Gupta, Y.M.

    1999-05-01

    In previous studies, ruby {ital R}-line shifts under shock compression and tension have been measured using the spontaneous luminescence from optically pumped samples. The signal intensities obtained are limited by the short time duration of the experiments in comparison to the long lifetime of the luminescence. We have investigated the use of stimulated emission for measuring {ital R}-line shifts in shocked ruby crystals. Experiments were performed both at ambient conditions and under shock compression to 6 GPa using an experimental configuration similar to that used for time resolved ruby luminescence measurements in previous shock wave studies. Signal gain due to stimulated emission was observed, with gains ranging from 1.1 to 3.4, in agreement with calculations performed for the particular experimental configuration used. The present results make a good case for incorporating this technique into the measurement of shock induced {ital R}-line shifts in ruby. {copyright} {ital 1999 American Institute of Physics.}

  9. Non-destructive measurement of carbonic anhydrase activity and the oxygen isotope composition of soil water

    NASA Astrophysics Data System (ADS)

    Jones, Sam; Sauze, Joana; Ogée, Jérôme; Wohl, Steven; Bosc, Alexandre; Wingate, Lisa

    2016-04-01

    oxygen isotope composition of ambient CO2. This non-destructive approach was tested through laboratory incubations of air-dried soils that were re-wetted with water of known isotopic composition. Performance was assessed by comparing estimates of the soil water oxygen isotope composition derived from open chamber flux measurements with those measured in the irrigation water and soil water extracted following incubations. The influence of soil pH and bovine carbonic anhydrase additions on these estimates was also investigated. Coherent values were found between the soil water composition estimates obtained from the dual steady state approach and those measured for irrigation waters. Estimates of carbonic anhydrase activity made using this approach also reflected well artificial increases to the concentration of carbonic anhydrase and indicated that this activity was sensitive to soil pH.

  10. Absolute Isotopic Abundance Ratios and the Accuracy of Δ47 Measurements

    NASA Astrophysics Data System (ADS)

    Daeron, M.; Blamart, D.; Peral, M.; Affek, H. P.

    2016-12-01

    Conversion from raw IRMS data to clumped isotope anomalies in CO2 (Δ47) relies on four external parameters: the (13C/12C) ratio of VPDB, the (17O/16O) and (18O/16O) ratios of VSMOW (or VPDB-CO2), and the slope of the triple oxygen isotope line (λ). Here we investigate the influence that these isotopic parameters exert on measured Δ47 values, using real-world data corresponding to 7 months of measurements; simulations based on randomly generated data; precise comparisons between water-equilibrated CO2 samples and between carbonate standards believed to share quasi-identical Δ47 values; reprocessing of two carbonate calibration data sets with different slopes of Δ47 versus T. Using different sets of isotopic parameters generally produces systematic offsets as large as 0.04 ‰ in final Δ47 values. What's more, even using a single set of isotopic parameters can produce intra- and inter-laboratory discrepancies in final Δ47 values, if some of these parameters are inaccurate. Depending on the isotopic compositions of the standards used for conversion to "absolute" values, these errors should correlate strongly with either δ13C or δ18O, or more weakly with both. Based on measurements of samples expected to display identical Δ47 values, such as 25°C water-equilibrated CO2 with different carbon and oxygen isotope compositions, or high-temperature standards ETH-1 and ETH-2, we conclude that the isotopic parameters used so far in most clumped isotope studies produces large, systematic errors controlled by the relative bulk isotopic compositions of samples and standards, which should be one of the key factors responsible for current inter-laboratory discrepancies. By contrast, the isotopic parameters of Brand et al. [2010] appear to yield accurate Δ47 values regardless of bulk isotopic composition. References:Brand, Assonov and Coplen [2010] http://dx.doi.org/10.1351/PAC-REP-09-01-05

  11. An isotopic approach to measuring nitrogen balance in caribou

    USGS Publications Warehouse

    Gustine, D.D.; Barboza, P.S.; Adams, L.G.; Farnell, R.G.; Parker, K.L.

    2011-01-01

    Nutritional restrictions in winter may reduce the availability of protein for reproduction and survival in northern ungulates. We refined a technique that uses recently voided excreta on snow to assess protein status in wild caribou (Rangifer tarandus) in late winter. Our study was the first application of this non-invasive, isotopic approach to assess protein status of wild caribou by determining dietary and endogenous contributions of nitrogen (N) to urinary urea. We used isotopic ratios of N (??15N) in urine and fecal samples to estimate the proportion of urea N derived from body N (p-UN) in pregnant, adult females of the Chisana Herd, a small population that ranged across the Alaska-Yukon border. We took advantage of a predator-exclosure project to examine N status of penned caribou in April 2006. Lichens were the primary forage (>40%) consumed by caribou in the pen and ?? 15N of fiber tracked the major forages in their diets. The ??15N of urinary urea for females in the pen was depleted relative (-1.3 ?? 1.0 parts per thousand [??], x?? ?? SD) to the ??15N of body N (2.7 ?? 0.7??). A similar proportion of animals in the exclosure lost core body mass (excluding estimates of fetal and uterine tissues; 55%) and body protein (estimated by isotope ratios; 54%). This non-invasive technique could be applied at various spatial and temporal scales to assess trends in protein status of free-ranging populations of northern ungulates. Intra- and inter-annual estimates of protein status could help managers monitor effects of foraging conditions on nutritional constraints in ungulates, increase the efficiency and efficacy of management actions, and help prepare stakeholders for potential changes in population trends. ?? 2010 The Wildlife Society.

  12. New method for lens thickness measurement by the frequency-shifted confocal feedback

    NASA Astrophysics Data System (ADS)

    Tan, Yidong; Zhu, Kaiyi; Zhang, Shulian

    2016-12-01

    We describe a new method for lens thickness and air gap measurement based on the frequency-shifted confocal feedback. The light intensity fluctuation is eliminated by the heterodyne modulation and the detection sensitivity is improved prominently by the frequency-shifted feedback effect. The measurement results for different materials and kinds of lenses are presented in the paper, including K9 plain glasses, fused silica plain glass, and K9 biconvex lens. The uncertainty of the axial positioning is better than 0.0005 mm and the accuracy reaches micron range. It is promising to be applied in the multi-layer interface positioning and measurement area.

  13. Measurements of CFC Isotope Changes in Firn, Stratospheric and Tropospheric Air

    NASA Astrophysics Data System (ADS)

    Allin, S.; Laube, J.; Witrant, E.; Kaiser, J.; McKenna, E.; Dennis, P.; Mulvaney, R.; Capron, E.; Martinerie, P.; Blunier, T.; Schwander, J.; Fraser, P. J.; Sturges, W. T.

    2014-12-01

    The degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone. Recent studies of CFC-12 (CCl2F2) have reported strong chlorine and carbon isotope fractionations in stratospheric and tropospheric samples, respectively. The δ(37Cl) variations were attributed to isotope dependent sink reactions, similar to effects seen in nitrous oxide (N2O), whereas adjustments to manufacturing processes were used to explain the δ(13C) changes. Using air archives to measure chlorine and carbon isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant chlorine isotope fractionation in the stratosphere, in common with CFC-12. We then use a 2-box model to estimate the expected tropospheric isotope signature of these gases, based on their emissions and transport history, as well as their measured stratospheric isotope fractionation constants (ɛapp). We also present long-term δ(37Cl) and δ(13C) trends of all three CFCs, determined from background tropospheric samples from the Cape Grim air archive (1978 - 2010) and firn air samples from the Arctic (NEEM, Greenland) and Antarctica (Fletcher Promontory). These measurements are compared to our model trends, leading to an evaluation of long-term chlorine and carbon isotope changes. This study also extends the novel approach to measuring trace gas isotope ratios in small air volumes, using a single-detector gas chromatography-mass spectrometry system.

  14. Satellite measurements of the isotopic composition of galactic cosmic rays

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Spalding, J. D.; Stone, E. C.; Vogt, R. E.

    1979-01-01

    The individual isotopes of galactic cosmic ray Ne, Mg, and Si at 100 MeV/nucleon were clearly resolved with an rms mass resolution of 0.20 amu. The results suggest the cosmic ray source is enriched in Ne-22, Mg-25, and Mg-26 when compared to the solar system. The ratio of (Mg-25)+(Mg-26) to Mg-24, which is approximately 0.49 compared to the solar system value of 0.27, suggest that the cosmic ray source and solar system material were synthesized under different conditions.

  15. Measurement of the n=2 Lamb shift in He+ by the anisotropy method

    NASA Astrophysics Data System (ADS)

    van Wijngaarden, A.; Kwela, J.; Drake, G. W. F.

    1991-04-01

    A high-precision measurement of the 2s 2S1/2-2p 2P1/2 Lamb shift in He+ by the quenching-anisotropy method is reported. The theory and experimental method are described in detail. The measured value of 14042.52+/-0.16 MHz (+/-11 parts per million) rivals the accuracy of Lamb-shift measurements in hydrogen by microwave resonance. By subtracting the known low-order terms in the Lamb shift, we interpret the results as a measurement of the order α(Zα)6mc2 and higher contributions to the electron self-energy GSE(Zα). The various contributions to the Lamb shift are discussed, and a revised value for GSE(Zα) at low Z is extracted from high-Z calculations. The theoretical value for the Lamb shift is 14042.51+/-0.2 MHz, in excellent agreement with experiment. The results provide the most sensitive available determination of GSE(Zα) for low Z. Measurements and calculations for hydrogen and other members of the isoelectronic sequence are discussed.

  16. Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in the VAHINE mesocosm experiments

    NASA Astrophysics Data System (ADS)

    Knapp, Angela N.; Fawcett, Sarah E.; Martínez-Garcia, Alfredo; Leblond, Nathalie; Moutin, Thierry; Bonnet, Sophie

    2016-08-01

    In a coastal lagoon with a shallow, 25 m water column off the southwest coast of New Caledonia, large-volume ( ˜ 50 m3) mesocosm experiments were undertaken to track the fate of newly fixed nitrogen (N). The mesocosms were intentionally fertilized with 0.8 µM dissolved inorganic phosphorus to stimulate diazotrophy. N isotopic evidence indicates that the dominant source of N fueling export production shifted from subsurface nitrate (NO3-) assimilated prior to the start of the 23-day experiments to N2 fixation by the end of the experiments. While the δ15N of the sinking particulate N (PNsink) flux changed during the experiments, the δ15N of the suspended PN (PNsusp) and dissolved organic N (DON) pools did not. This is consistent with previous observations that the δ15N of surface ocean N pools is less responsive than that of PNsink to changes in the dominant source of new N to surface waters. In spite of the absence of detectable NO3- in the mesocosms, the δ15N of PNsink indicated that NO3- continued to fuel a significant fraction of export production (20 to 60 %) throughout the 23-day experiments, with N2 fixation dominating export after about 2 weeks. The low rates of organic N export during the first 14 days were largely supported by NO3-, and phytoplankton abundance data suggest that sinking material primarily comprised large diatoms. Concurrent molecular and taxonomic studies indicate that the diazotroph community was dominated by diatom-diazotroph assemblages (DDAs) at this time. However, these DDAs represented a minor fraction (< 5 %) of the total diatom community and contributed very little new N via N2 fixation; they were thus not important for driving export production, either directly or indirectly. The unicellular cyanobacterial diazotroph, a Cyanothece-like UCYN-C, proliferated during the last phase of the experiments when N2 fixation, primary production, and the flux of PNsink increased significantly, and δ15N budgets reflected a predominantly

  17. Nitrogen isotopic evidence for a shift from nitrate- to diazotroph-fueled export production in VAHINE mesocosm experiments

    NASA Astrophysics Data System (ADS)

    Knapp, A. N.; Fawcett, S. E.; Martínez-Garcia, A.; Leblond, N.; Moutin, T.; Bonnet, S.

    2015-12-01

    In a shallow, coastal lagoon off the southwest coast of New Caledonia, large-volume (~ 50 m3) mesocosm experiments were undertaken to track the fate of newly fixed nitrogen (N). The mesocosms were intentionally fertilized with 0.8 μM dissolved inorganic phosphorus (DIP) to stimulate diazotrophy. N isotopic evidence indicates that the dominant source of N fueling export production shifted from subsurface nitrate (NO3-) assimilated prior to the start of the 23 day experiments to N2 fixation by the end of the experiments. While the δ15N of the sinking particulate N (PNsink) flux changed during the experiments, the δ15N of the suspended PN (PNsusp) and dissolved organic N (DON) pools did not. This is consistent with previous observations that the δ15N of surface ocean N pools is less responsive than that of PNsink to changes in the dominant source of new N to surface waters. In spite of the absence of detectable NO3- in the mesocosms, the δ15N of PNsink indicated that NO3- continued to fuel a significant fraction of export production (20 to 60 %) throughout the 23 day experiments, with N2 fixation dominating export after about two weeks. The low rates of primary productivity and export production during the first 14 days were primarily supported by NO3-, and phytoplankton abundance data suggest that export was driven by large diatoms sinking out of surface waters. Concurrent molecular and taxonomic studies indicate that the diazotroph community was dominated by diatom-diazotroph assemblages (DDAs) at this time. However, these DDAs represented a minor fraction (< 5 %) of the total diatom community and contributed very little new N via N2 fixation; they were thus not important for driving export production, either directly or indirectly. The unicellular cyanobacterial diazotroph, a Cyanothece-like UCYN-C, proliferated during the last phase of the experiments when N2 fixation, primary production, and the flux of PNsink increased significantly, and δ15N budgets

  18. Enhanced high dynamic range 3D shape measurement based on generalized phase-shifting algorithm

    NASA Astrophysics Data System (ADS)

    Wang, Minmin; Du, Guangliang; Zhou, Canlin; Zhang, Chaorui; Si, Shuchun; Li, Hui; Lei, Zhenkun; Li, YanJie

    2017-02-01

    Measuring objects with large reflectivity variations across their surface is one of the open challenges in phase measurement profilometry (PMP). Saturated or dark pixels in the deformed fringe patterns captured by the camera will lead to phase fluctuations and errors. Jiang et al. proposed a high dynamic range real-time three-dimensional (3D) shape measurement method (Jiang et al., 2016) [17] that does not require changing camera exposures. Three inverted phase-shifted fringe patterns are used to complement three regular phase-shifted fringe patterns for phase retrieval whenever any of the regular fringe patterns are saturated. Nonetheless, Jiang's method has some drawbacks: (1) the phases of saturated pixels are estimated by different formulas on a case by case basis; in other words, the method lacks a universal formula; (2) it cannot be extended to the four-step phase-shifting algorithm, because inverted fringe patterns are the repetition of regular fringe patterns; (3) for every pixel in the fringe patterns, only three unsaturated intensity values can be chosen for phase demodulation, leaving the other unsaturated ones idle. We propose a method to enhance high dynamic range 3D shape measurement based on a generalized phase-shifting algorithm, which combines the complementary techniques of inverted and regular fringe patterns with a generalized phase-shifting algorithm. Firstly, two sets of complementary phase-shifted fringe patterns, namely the regular and the inverted fringe patterns, are projected and collected. Then, all unsaturated intensity values at the same camera pixel from two sets of fringe patterns are selected and employed to retrieve the phase using a generalized phase-shifting algorithm. Finally, simulations and experiments are conducted to prove the validity of the proposed method. The results are analyzed and compared with those of Jiang's method, demonstrating that our method not only expands the scope of Jiang's method, but also improves

  19. Observation of the Goos-Hänchen shift in graphene via weak measurements

    NASA Astrophysics Data System (ADS)

    Chen, Shizhen; Mi, Chengquan; Cai, Liang; Liu, Mengxia; Luo, Hailu; Wen, Shuangchun

    2017-01-01

    We report the observation of the Goos-Hänchen effect in graphene via a weak value amplification scheme. We demonstrate that the amplified Goos-Hänchen shift in weak measurements is sensitive to the variation of graphene layers. Combining the Goos-Hänchen effect with weak measurements may provide important applications in characterizing the parameters of graphene.

  20. Chlorine and carbon isotope measurements can help assessing the effectivenes of a zero valent iron barrier

    NASA Astrophysics Data System (ADS)

    Cretnik, S.; Audi, C.; Bernstein, A.; Palau, J.; Soler, A.; Elsner, M.

    2012-04-01

    Chlorinated aliphatic hydrocarbons (CAH's) such as trichloroethene (TCE), cis-dichloroethene (cis-DCE) and vinylchloride (VC) are extensively used in industrial applications. One of the most promising remediation techniques for CAH's in groundwater is their removal via abiotic reductive dechlorination using Zero Valent Iron (ZVI). This is applied for the treatment of contaminated sites by installing permeable reactive barriers (PRB). In this study, isotope fractionation of chlorinated ethylenes in transformation by cast iron has been investigated, because such types of iron are commonly used in PRBs. Batch experiments have been carried out in closed flasks, containing cast iron with aqueous solutions of TCE, cDCE and VC. These substrates and their respective products have been monitored by headspace samplings for their concentration (by GC-FID) and isotope fractionation of carbon and chlorine (by GC-IRMS). A decreasing reactivity trend was observed when compounds contain less chlorine atoms, with differences in rate constants of about one order of magnitude between each of the substances TCE > cDCE > VC. This resulted in the accumulation of products with fewer chlorine atoms. Therefore a similar observation can be expected if degradation in the field is incomplete, for example in the case of aged or improperly designed PRB. Pronounced carbon and chlorine isotope fractionation was measured for each of the compounds, and characteristic dual isotope plots (C, Cl) were obtained for TCE and cDCE. These results may serve as an important reference for the interpretation of isotope data from field sites, since stable isotope fractionation is widely recognized as robust indicator for such pollutant transformations. However, carbon isotope fractionation in a given parent compound may be caused by either abiotic or biotic degradation. In the field, it can therefore be difficult to delineate the contribution of abiotic transformation by PRB in the presence of ongoing

  1. Wind speed measurements of Doppler-shifted absorption lines using two-beam interferometry.

    PubMed

    Pierce, Robert M; Roark, Shane E

    2012-04-20

    Wind speed can be measured remotely, with varying degrees of success, using interferometry of Doppler-shifted optical spectra. Under favorable conditions, active systems using laser pulse backscatter are capable of high resolution; passive systems, which measure Doppler shifts of atmospheric emission lines in the mesosphere, have also been shown. Two-beam interferometry of Doppler-shifted absorption lines has not been previously investigated; we describe such an effort here. Even in a well-defined environment, measuring absorption line Doppler shifts requires overcoming several technical hurdles in order to obtain sensitivity to wind speeds on the order of 10 m/s. These hurdles include precise knowledge of the shape of the absorption line, tight, stable filtering, and understanding precisely how an interferometer phase should respond to a change in the absorption profile. We discuss the instrument design, a Michelson interferometer and Fabry-Perot filter, and include an analysis of how to choose the optimal optical path difference of the two beams for a given spectrum and filter. We discuss two beam interferometric measurements of emission line and absorption line Doppler shifts, and include an illustration of the effects of filtering on LIDAR Doppler interferometry. Finally, we discuss the construction and implementation of a Michelson interferometer used to measure Doppler shifts of oxygen absorption lines and present results obtained with 5 m/s wind speed measurement precision. Although the theoretical shot noise limited Doppler wind speed measurement of the system described can be less than 1 m/s, the instrument's resolution limit is dominated by residual filter instability. Application of absorption line interferometry to determine atmospheric wind speeds remains problematic.

  2. Evaluation of the combined measurement uncertainty in isotope dilution by MC-ICP-MS.

    PubMed

    Fortunato, G; Wunderli, S

    2003-09-01

    The combination of metrological weighing, the measurement of isotope amount ratios by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) and the use of high-purity reference materials are the cornerstones to achieve improved results for the amount content of lead in wine by the reversed isotope dilution technique. Isotope dilution mass spectrometry (IDMS) and reversed IDMS have the potential to be a so-called primary method, with which close comparability and well-stated combined measurement uncertainties can be obtained. This work describes the detailed uncertainty budget determination using the ISO-GUM approach. The traces of lead in wine were separated from the matrix by ion exchange chromatography after HNO(3)/H(2)O(2) microwave digestion. The thallium isotope amount ratio ( n((205)Tl)/ n((203)Tl)) was used to correct for mass discrimination using an exponential model approach. The corrected lead isotope amount ratio n((206)Pb)/ n((208)Pb) for the isotopic standard SRM 981 measured in our laboratory was compared with ratio values considered to be the least uncertain. The result has been compared in a so-called pilot study "lead in wine" organised by the CCQM (Comité Consultatif pour la Quantité de Matière, BIPM, Paris; the highest measurement authority for analytical chemical measurements). The result for the lead amount content k(Pb) and the corresponding expanded uncertainty U given by our laboratory was:k(Pb)=1.329 x 10-10mol g-1 (amount content of lead in wine)U[k(Pb)]=1.0 x 10-12mol g-1 (expanded uncertainty U=kxuc, k=2)The uncertainty of the main influence parameter of the combined measurement uncertainty was determined to be the isotope amount ratio R(206,B) of the blend between the enriched spike and the sample.

  3. Determination of Forest Canopy Carbon Respiration From FTIR Measurements of Carbon Dioxide Isotopic Ratios

    NASA Astrophysics Data System (ADS)

    Cambaliza, M. O.; Mount, G.; Lamb, B.; Westberg, H.

    2004-12-01

    Isotopic analysis of atmospheric carbon dioxide provides a means to understand the complex carbon exchange between the biosphere and the atmosphere. Measurements of isotopic concentrations have traditionally been done by laboratory mass spectrometry analysis of grab samples taken from distant field sites with consequent limits on the number and frequency of measurements. In this work, we describe the development of an insitu carbon dioxide isotope analysis method based on Fourier transform infrared (FTIR) spectroscopy. Using molecular absorption in a 4-pass 1-meter length cell in the 2100 to 2600 cm-1 region of the 12CO2 and 13CO2 isotopic vibration-rotation bands, concentrations of both isotopes are measured, and from their ratio, \\delta13CO2 is determined. Coupled with the disjunct eddy covariance technique, CO2 fluxes can also be measured. We demonstrate the capabilities of this technique using measurements in a poplar forest plantation near Boardman, Oregon. Beer's law and a nonlinear least squares analysis algorithm were used to analyze the data. Careful attention was paid to avoid analysis in spectral regions of nonlinear absorption. Sequential measurements were made at seven levels on a 25-meter tower erected in an 11-m canopy. Carbon dioxide concentrations are calculated to a precision of about 0.5 ppmv, and \\delta13CO2 to about 0.2‰ precision. In this work, we present initial results of temporal and vertical variations of CO2 concentrations and \\delta13CO2 in this forest.

  4. Light shift measurements in a Cesium Fountain without the use of mechanical shutters

    NASA Technical Reports Server (NTRS)

    Tjoelker, Robert L.; Enzer, D. G.; Klipstein, W. M.

    2005-01-01

    We present measurements confirming operation of a cesium fountain frequency standard with light shift below 10^-15 (and with evidence suggesting it is several orders of magnitude below this level) but without the use of mechanical shutters. Suppression of the light shift is realized using a master-slave laser configuration by reducing the overall optical power delivered to the physics package as well as spoiling the injection of the slave, causing it to lase far off resonance (1-2 nm) as proposed by the authors several years ago [l]. In the absence of any mitigation, this (AC Stark) shift, due to near-resonant laser light reaching the atoms during their microwave interrogation period, is the largest shift in such frequency standards (2x10^-11 for Our fountain). Mechanical shutters provided adequate light attenuation but have been prone to failure.

  5. Historic Carbon Isotopic Shifts in Pinyon Pines and Woodland Junipers are Unprecedented During the Quaternary History of These Taxa

    NASA Astrophysics Data System (ADS)

    van de Water, P. K.; Leavitt, S. W.; Betancourt, J. L.

    2003-12-01

    Packrat (Neotoma) midden macrofossil records from arid and semiarid western North America provide evidence that pinyon pines and woodland junipers have grown together for at least the past 50,000 radiocarbon years. The midden records show that this association was sustained despite large-scale changes in climate and atmospheric CO2 concentrations over the past 50 millenia. Reconstruction of physiological parameters, using 13C analysis of a select sample of pinyon pine and juniper macrofossils from radiocarbon-dated ancient packrat middens, shows distinct physical responses to these changes despite a offset between the carbon isotopic values of the two genera, with pinyon pines having consistently lower 13C values than junipers. Remarkably, analysis of historic (from herbarium sheets) and present-day (from field collections) materials from northern Arizona and the Four-Corners region indicates that the long-term offset between the carbon isotopic values of pinyon pines and woodland junipers has inverted; with the junipers now providing isotopically lighter values than the pinyon pines. This reversal began in the late 1800's to early 1900's and has widened over the past century. The inverted isotopic offsets in the historic period may be due to the unprecedented levels of carbon dioxide and other trace gases in the atmosphere.

  6. Isotope composition of sulphate in acid mine drainage as measure of bacterial oxidation

    USGS Publications Warehouse

    Taylor, B.E.; Wheeler, M.C.; Nordstrom, D.K.

    1984-01-01

    The formation of acid waters by oxidation of pyrite-bearing ore deposits, mine tailing piles, and coal measures is a complex biogeochemical process and is a serious environmental problem. We have studied the oxygen and sulphur isotope geochemistry of sulphides, sulphur, sulphate and water in the field and in experiments to identify sources of oxygen and reaction mechanisms of sulphate formation. Here we report that the oxygen isotope composition of sulphate in acid mine drainage shows a large variation due to differing proportions of atmospheric- and water-derived oxygen from both chemical and bacterially-mediated oxidation. 18O-enrichment of sulphate results from pyrite oxidation facilitated by Thiobacillus ferrooxidans in aerated environments. Oxygen isotope analysis may therefore be useful in monitoring the effectiveness of abatement programmes designed to inhibit bacterial oxidation. Sulphur isotopes show no significant fractionation between pyrite and sulphate, indicating the quantitative insignificance of intermediate oxidation states of sulphur under acid conditions. ?? 1984 Nature Publishing Group.

  7. First total-absorption spectroscopy measurement on the neutron-rich Cu isotopes

    NASA Astrophysics Data System (ADS)

    Naqvi, F.; Spyrou, A.; Liddick, S. N.; Larsen, A. C.; Guttormsen, M.; Bleuel, D. L.; Campo, L. C.; Couture, A.; Crider, B. P.; Dombos, A. C.; Ginter, T.; Lewis, R.; Mosby, S.; Perdikakis, G.; Prokop, C. P.; Quinn, S. J.; Renstrom, T.; Rubio, B.; Siem, S.

    2015-10-01

    The first beta-decay studies of 73-71Cu isotopes using the Total Absorption Spectroscopy (TAS) will be reported. The Cu isotopes have one proton outside the Z = 28 shell and hence are good candidates to probe the single-particle structure in the region.Theories predict weakening of the Z = 28 shell gap due to the tensor interaction between the valence πν single-particle orbitals. Comparing the beta-decay strength distributions in the daughter Zn isotopes to the theoretical calculations will provide a stringent test of the predictions. The experiment was performed at the National Superconducting Cyclotron Laboratory (NSCL) employing the TAS technique with the Summing NaI(Tl) detector, while beta decays were measured in the NSCL beta-counting system. The experimentally obtained total absorption spectra for the neutron-rich Cu isotopes will be presented and the implications of the extracted beta-feeding intensities will be discussed.

  8. Isotopic abundance measurements on solid nuclear-type samples by glow discharge mass spectrometry.

    PubMed

    Betti, M; Rasmussen, G; Koch, L

    1996-07-01

    A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrometry (TIMS). For boron and lithium at microg/g-ng/g levels, the two methods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, the GDMS raw data are complementary with those values obtained from physical non-destructive techniques.

  9. Application of lead and strontium isotope ratio measurements for the origin assessment of uranium ore concentrates.

    PubMed

    Varga, Zsolt; Wallenius, Maria; Mayer, Klaus; Keegan, Elizabeth; Millet, Sylvain

    2009-10-15

    Lead and strontium isotope ratios were used for the origin assessment of uranium ore concentrates (yellow cakes) for nuclear forensic purposes. A simple and low-background sample preparation method was developed for the simultaneous separation of the analytes followed by the measurement of the isotope ratios by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The lead isotopic composition of the ore concentrates suggests applicability for the verification of the source of the nuclear material and by the use of the radiogenic (207)Pb/(206)Pb ratio the age of the raw ore material can be calculated. However, during data interpretation, the relatively high variation of the lead isotopic composition within the mine site and the generally high contribution of natural lead as technological contamination have to be carefully taken into account. The (87)Sr/(86)Sr isotope ratio is less prone to the variation within one mine site and less affected by the production process, thus it was found to be a more purposeful indicator for the origin assessment and source verification than the lead. The lead and strontium isotope ratios measured and the methodology developed provide information on the initial raw uranium ore used, and thus they can be used for source attribution of the uranium ore concentrates.

  10. High sensitivity measurement of amino acid isotope enrichment using liquid chromatography-mass spectrometry.

    PubMed

    van Eijk, Hans M H; Wijnands, Karolina A P; Bessems, Babs A F M; Olde Damink, Steven W; Dejong, Cornelis H C; Poeze, Martijn

    2012-09-15

    Measurement of the incorporation or conversion of infused stable isotope enriched metabolites in vivo such as amino acids plays a key role in metabolic research. Specific routes are frequently probed in knockout mouse models limiting the available amount of sample. Although less precise as compared to combustion-isotope ratio mass spectrometry (C-IRMS), gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS) techniques are therefore often the method of choice to measure isotopic enrichment of target metabolites. However, under conditions of metabolic depletion, the precision of these systems becomes limiting. In this paper, studies were performed to enhance the sensitivity and precision of isotope enrichment measurements using LC-MS. Ion-statistics and resolution were identified as critical factors for this application when using a linear trap mass spectrometer. The combination with an automated pre-column derivatization and a carefully selected solvent mix allowed us to measure isotopic enrichments down to 0.005% at plasma concentrations as low as 5 μmol/l, an improvement by a factor of 100 compared to alternative methods. The resulting method now allowed measurement of the in vivo conversion of the amino acid arginine into citrulline as a marker for the production of nitric oxide in an in vivo murine endotoxemia model with depleted plasma levels of arginine and citrulline.

  11. Methane oxidation in biofilters measured by mass-balance and stable isotope methods.

    PubMed

    Powelson, D K; Chanton, J P; Abichou, T

    2007-01-15

    Simultaneous flux and isotope measurements on compost and sand biofilters showed that the fraction of CH4 oxidized, calculated from delta13C measurements using a closed system model (f(oxir,C)), averaged only 0.455 of the fraction oxidized based on mass-balance measurements (f(oxm)). The discrepancy between f(oxm) and f(oxir,C) may be partly due to complete oxidation of a portion of the inflow gas, thereby eliminating its contribution to the emitted methane on which isotopic measurements are conducted. To relate f(oxir,C) and f(oxm) a simple binary closed-system model is proposed that assumes that f(oxir,C) refers to only part of the inflow, P, and that the remainder of inflow (1 - P) is completely oxidized before reaching the outlet. This model is compared to the standard open-system model. The H-isotope fraction oxidized (f(oxir,H)) was determined for a subset of samples and found to be not significantly different from f(oxir,C). The carbon isotope fractionation factor, alphaox,C = 1.0244, and the H-isotope fractionation factor, alphaox,H = 1.2370, were determined by incubation studies. Delta13C measurements indicated that the emitted flow was more strongly oxidized by the compost biofilters (f(oxir,C) = 0.362, f(oxm) = 0.757) than the sand biofilters (f(oxir,C) = 0.222, f(oxm) = 0.609).

  12. PC/FRAM: New capabilities for the gamma-ray spectrometry measurement of plutonium isotopic composition

    SciTech Connect

    Sampson, T.E.; Kelley, T.A.; Cremers, T.L.; Konkel, T.R.; Friar, R.J.

    1995-10-01

    We describe the new capability of and.present measurement results from the PC/FRAM plutonium isotopic analysis code. This new code allows data acquisition from a single coaxial germanium detector and analysis over an energy range from 120 keV to above I MeV. For the first time we demonstrate a complete isotopic analysis using only gamma rays greater than 200 keV in energy. This new capability allows the measurement of the plutonium isotopic composition of items inside shielded or heavy-walled containers without having to remove the items from the container. This greatly enhances worker safety by reducing handling and the resultant radiation exposure. Another application allows international inspectors to verify the contents of items inside sealed, long-term storage containers that may not be opened for national security or treaty compliance reasons. We present measurement results for traditional planar germanium detectors as well as coaxial detectors measuring shielded and unshielded samples.

  13. Measurement of the nuclear polarization of hydrogen and deuterium molecules using a Lamb-shift polarimeter.

    PubMed

    Engels, Ralf; Gorski, Robert; Grigoryev, Kiril; Mikirtychyants, Maxim; Rathmann, Frank; Seyfarth, Hellmut; Ströher, Hans; Weiss, Philipp; Kochenda, Leonid; Kravtsov, Peter; Trofimov, Viktor; Tschernov, Nikolay; Vasilyev, Alexander; Vznuzdaev, Marat; Paetz gen Schieck, Hans

    2014-10-01

    Lamb-shift polarimeters are used to measure the nuclear polarization of protons and deuterons at energies of a few keV. In combination with an ionizer, the polarization of hydrogen and deuterium atoms was determined after taking into account the loss of polarization during the ionization process. The present work shows that the nuclear polarization of hydrogen or deuterium molecules can be measured as well, by ionizing the molecules and injecting the H2(+) (or D2(+)) ions into the Lamb-shift polarimeter.

  14. Phase-shift based BOTDA measurements tolerant to non-local effects

    NASA Astrophysics Data System (ADS)

    Urricelqui, Javier; Sagues, Mikel; Loayssa, Alayn

    2013-05-01

    We demonstrate a BOTDA sensor based on the use of the Brillouin phase-shift that performs measurements tolerant to non-local effects. This technique raises opportunities to increase the distance covered by these sensors and the maximum optical power of the probe wave injected to the fiber. As a result, the system has the potential to increase the SNR achieved at the last meters of the fiber. Proof-of-concept experiments demonstrate unaltered measurements of the phase-shift spectrum in a 20Km long fiber for large frequency-dependent distortions of the pump pulse.

  15. Measurement of the nuclear polarization of hydrogen and deuterium molecules using a Lamb-shift polarimeter

    SciTech Connect

    Engels, Ralf Gorski, Robert; Grigoryev, Kiril; Mikirtychyants, Maxim; Rathmann, Frank; Seyfarth, Hellmut; Ströher, Hans; Weiss, Philipp; Kochenda, Leonid; Kravtsov, Peter; Trofimov, Viktor; Tschernov, Nikolay; Vasilyev, Alexander; Vznuzdaev, Marat; Schieck, Hans Paetz gen.

    2014-10-15

    Lamb-shift polarimeters are used to measure the nuclear polarization of protons and deuterons at energies of a few keV. In combination with an ionizer, the polarization of hydrogen and deuterium atoms was determined after taking into account the loss of polarization during the ionization process. The present work shows that the nuclear polarization of hydrogen or deuterium molecules can be measured as well, by ionizing the molecules and injecting the H{sub 2}{sup +} (or D{sub 2}{sup +}) ions into the Lamb-shift polarimeter.

  16. Self-density frequency shift measurements of Raman N 2 Q-branch transitions

    NASA Astrophysics Data System (ADS)

    Lavorel, B.; Chaux, R.; Saint-Loup, R.; Berger, H.

    1987-04-01

    We report stimulated Raman investigations of N 2 Q-branch transitions in view to measure the self-density frequency shift. These measurements performed at 295 K over the density range 0.02-0.8 Amagat lead to a mean shift value equal to -5.5×10 -3 cm -1/Amagat. Moreover, our data extrapolated at zero density allowed new refinements of the N 2 molecular constants: v0=2329.91165 (17) cm -1, B1- B0=-0.0173714 (22) cm -1 and D1- D0=(7.6±5.0)×10 -9 cm -1.

  17. An automated method for 'clumped-isotope' measurements on small carbonate samples.

    PubMed

    Schmid, Thomas W; Bernasconi, Stefano M

    2010-07-30

    Clumped-isotope geochemistry deals with the state of ordering of rare isotopes in molecules, in particular with their tendency to form bonds with other rare isotopes rather than with the most abundant ones. Among its possible applications, carbonate clumped-isotope thermometry is the one that has gained most attention because of the wide potential of applications in many disciplines of earth sciences. Clumped-isotope thermometry allows reconstructing the temperature of formation of carbonate minerals without knowing the isotopic composition of the water from which they were formed. This feature enables new approaches in paleothermometry. The currently published method is, however, limited by sample weight requirements of 10-15 mg and because measurements are performed manually. In this paper we present a new method using an automated sample preparation device coupled to an isotope ratio mass spectrometer. The method is based on the repeated analysis (n = 6-8) of 200 microg aliquots of sample material and completely automated measurements. In addition, we propose to use precisely calibrated carbonates spanning a wide range in Delta(47) instead of heated gases to correct for isotope effects caused by the source of the mass spectrometer, following the principle of equal treatment of the samples and standards. We present data for international standards (NBS 19 and LSVEC) and different carbonates formed at temperatures exceeding 600 degrees C to show that precisions in the range of 10 to 15 ppm (1 SE) can be reached for repeated analyses of a single sample. Finally, we discuss and validate the correction procedure based on high-temperature carbonates instead of heated gases.

  18. Reporting and measurement of mass-dependent and mass-independent fractionation of mercury isotopes

    NASA Astrophysics Data System (ADS)

    Bergquist, B. A.; Blum, J. D.

    2007-12-01

    Hg isotope analysis by MC-ICP-MS is an important new approach for fingerprinting Hg sources and monitoring Hg redox reactions and bioaccumulation, especially with the recent discovery of mass independent Hg isotope fractionation. Unfortunately research groups have adopted different standards, definitions of delta values, and methods of isotopic measurement. We suggest that a single standard, NIST SRM 3133, be adopted for reporting the isotopic variability of Hg isotopes. Isotope ratios should be determined by sample-standard bracketing (SSB) during analysis and reported as permil (‰) deviation from SRM 3133. For the highest precision and accuracy, a Tl internal standard along with SSB should be used to correct instrumental mass bias. Measurement routines should also include on-peak zero corrections and matching of concentration and matrix between the samples and bracketing standard. For samples that display mass-dependent fractionation (MDF), only one delta value needs to be reported (δ202/198Hg). Mass-independent fractionation (MIF) (Jackson et al., 2006; Bergquist et al., 2006; Bergquist and Blum, submitted) requires additional nomenclature, and we suggest reporting MIF as the deviation in isotope ratios from the theoretical mass dependent kinetic isotope fractionation (Δxxx/198Hg)¬. External reproducibility should be monitored by analysis of secondary standards. For studies of MDF, we use an in-house secondary standard solution made from metallic Hg mined from Almaden Spain and obtain a δ202Hg of -0.55 ±0.06‰ (2SD). For studies of MIF, we use NRCC CRM DORM-2 (dogfish muscle) and obtain a mean value of δ202Hg of +0.19 ±0.13‰ (2SD), Δ201Hg of +0.89 ±0.07‰ (2SD) , and Δ199Hg of +1.07 ±0.08‰ (2SD).

  19. Hydrogen bond geometries and proton tautomerism of homoconjugated anions of carboxylic acids studied via H/D isotope effects on 13C NMR chemical shifts.

    PubMed

    Guo, Jing; Tolstoy, Peter M; Koeppe, Benjamin; Golubev, Nikolai S; Denisov, Gleb S; Smirnov, Sergei N; Limbach, Hans-Heinrich

    2012-11-26

    Ten formally symmetric anionic OHO hydrogen bonded complexes, modeling Asp/Glu amino acid side chain interactions in nonaqueous environment (CDF(3)/CDF(2)Cl solution, 200-110 K) have been studied by (1)H, (2)H, and (13)C NMR spectroscopy, i.e. intermolecularly H-bonded homoconjugated anions of acetic, chloroacetic, dichloroacetic, trifluoroacetic, trimethylacetic, and isobutyric acids, and intramolecularly H-bonded hydrogen succinate, hydrogen rac-dimethylsuccinate, hydrogen maleate, and hydrogen phthalate. In particular, primary H/D isotope effects on the hydrogen bond proton signals as well as secondary H/D isotope effects on the (13)C signals of the carboxylic groups are reported and analyzed. We demonstrate that in most of the studied systems there is a degenerate proton tautomerism between O-H···O(-) and O(-)···H-O structures which is fast in the NMR time scale. The stronger is the proton donating ability of the acid, the shorter and more symmetric are the H-bonds in each tautomer of the homoconjugate. For the maleate and phthalate anions exhibiting intramolecular hydrogen bonds, evidence for symmetric single well potentials is obtained. We propose a correlation between H/D isotope effects on carboxylic carbon chemical shifts and the proton transfer coordinate, q(1) = ½(r(OH) - r(HO)), which allows us to estimate the desired OHO hydrogen bond geometries from the observed (13)C NMR parameters, taking into account the degenerate proton tautomerism.

  20. Making an honest measurement scale out of the oxygen isotope delta-values.

    PubMed

    Gat, Joel R; DeBievre, Paul

    2002-01-01

    The differential measurement of the abundance of oxygen isotopes based on reference materials, such as VSMOW for the case of water, was used because the precision of the absolute mass-spectrometric determination of the abundance fell short of the differences to be measured. Since then these measurements have been much improved, so that a calibration scheme of the oxygen isotope abundance in water, carbonates, silica, phosphates, sulfates, nitrates and organic materials is suggested, based on an accredited primary standard of oxygen in air and using standard fluorination and O(2) to CO(2) conversion techniques. Copyright 2002 John Wiley & Sons, Ltd.

  1. (Sample) Size Matters: Defining Error in Planktic Foraminiferal Isotope Measurement

    NASA Astrophysics Data System (ADS)

    Lowery, C.; Fraass, A. J.

    2015-12-01

    Planktic foraminifera have been used as carriers of stable isotopic signals since the pioneering work of Urey and Emiliani. In those heady days, instrumental limitations required hundreds of individual foraminiferal tests to return a usable value. This had the fortunate side-effect of smoothing any seasonal to decadal changes within the planktic foram population, which generally turns over monthly, removing that potential noise from each sample. With the advent of more sensitive mass spectrometers, smaller sample sizes have now become standard. This has been a tremendous advantage, allowing longer time series with the same investment of time and energy. Unfortunately, the use of smaller numbers of individuals to generate a data point has lessened the amount of time averaging in the isotopic analysis and decreased precision in paleoceanographic datasets. With fewer individuals per sample, the differences between individual specimens will result in larger variation, and therefore error, and less precise values for each sample. Unfortunately, most workers (the authors included) do not make a habit of reporting the error associated with their sample size. We have created an open-source model in R to quantify the effect of sample sizes under various realistic and highly modifiable parameters (calcification depth, diagenesis in a subset of the population, improper identification, vital effects, mass, etc.). For example, a sample in which only 1 in 10 specimens is diagenetically altered can be off by >0.3‰ δ18O VPDB or ~1°C. Additionally, and perhaps more importantly, we show that under unrealistically ideal conditions (perfect preservation, etc.) it takes ~5 individuals from the mixed-layer to achieve an error of less than 0.1‰. Including just the unavoidable vital effects inflates that number to ~10 individuals to achieve ~0.1‰. Combining these errors with the typical machine error inherent in mass spectrometers make this a vital consideration moving forward.

  2. Influence of explanatory and confounding variables on HRQoL after controlling for measurement bias and response shift in measurement.

    PubMed

    Gandhi, Pranav K; Ried, L Douglas; Kimberlin, Carole L; Kauf, Teresa L; Huang, I-Chan

    2013-12-01

    The purpose of this study was to examine the influence of explanatory and confounding variables on health-related quality of life after accounting for response shift, measurement bias and response shift in measurement using structural equation modeling. Hypertensive patients with coronary artery disease randomized to anti-hypertensive treatment, completed the ShortForm-36 questionnaire at both baseline and 1 year (n = 788). Three measurement biases were found and all three were considered as response shift in measurement. Older patients reported worse scores for both physical functioning (PF) and role-physical at baseline and 1 year later compared to younger patients; and males reported better PF than females after conditioning on the latent trait of general physical health. Before controlling for response shift, patients' PF scores were not statistically different over time; however, PF scores significantly improved (p < 0.01) after controlling for recalibration response shift. Assessment of how patients perceive their change in health-related quality of life over time is warranted.

  3. A new serial pooling method of shifted tree ring blocks to construct millennia long tree ring isotope chronologies with annual resolution.

    PubMed

    Boettger, Tatjana; Friedrich, Michael

    2009-03-01

    The study presents a new serial pooling method of shifted tree ring blocks for the building of isotope chronologies. This method combines the advantages of traditional 'serial' and 'intertree' pooling, and can be recommended for the construction of sub-regional long isotope chronologies with sufficient replication, and on annual resolution, especially for the case of extremely narrow tree rings. For Scots pines (Pinus sylvestris L., Khibiny Low Mountains, NW Russia) and Silver firs (Abies alba Mill., Franconia, Southern Germany), serial pooling of five consecutive tree rings seems appropriate because the species- and site-specific particularities lead to blurs of climate linkages in their tree rings for the period up to ca. five years back. An equivalent to a five-year running means that curve gained on the base annual data sets of single trees can be derived from the analysis of yearly shifted five-year blocks of consecutive tree rings, and therefore, with approximately 20% of the expense. Good coherence of delta(13)C- and delta(18)O-values between calculated means of annual total rings or late wood data and means of five-year blocks of consecutive total tree rings analysed experimentally on most similar material confirms this assumption.

  4. Importance of regression processes in evaluating analytical errors in argon isotope measurements

    NASA Astrophysics Data System (ADS)

    Min, K.; Powell, L.

    2003-04-01

    For 40Ar/39Ar dating, it is required to measure five argon isotopes of 36Ar ~ 40Ar with high precision. The process involves isolating the purified gas in an analytical volume and cyclically measuring the abundance of each Ar isotope using an electron multiplier to minimize detector calibration and sensitivity errors. Each cycle is composed of maximum several tens of fundamental digital voltmeter (DVM) readings per isotope. Since the abundance of each isotope varies over analytical time, it is necessary to statistically treat the data to obtain most probable estimates. The readings on one mass from one cycle are commonly averaged to be treated as a single data point for regression. The y-intercept derived from the regression is assumed to represent an initial isotopic abundance at the time (t0) when the gas was introduced to the analytical volume. This procedure is repeated for each Ar isotope. About 0.2 % precision is often claimed for 40Ar and 39Ar measurements for properly irradiated, K-rich samples. The uncertainty of the calculated y-intercept varies depending on the distribution of the averaged DVM readings as well as the model equation used in regression. The “internal error” associated with the distribution of individual DVM readings in the group average are, however, commonly ignored in the regression procedure probably due to complex weighting processes. Including the internal error may significantly increase the uncertainties of 40Ar/39Ar ages especially for young samples because the analytical errors (from isotopic ratio measurements) are more dominant than the systematic errors (from decay constant, age of neutron flux monitor, etc). Alternative way to include the internal error is to regress all of the DVM readings with a single equation, then propagate the regression error into y-intercept calculation. In any case, it is necessary to propagate uncertainties derived from fundamental readings to properly estimate analytical errors in 40Ar/39Ar age

  5. Paired measurements of K and Mg isotopes and clay authigenesis in marine sediments

    NASA Astrophysics Data System (ADS)

    Santiago Ramos, D. P.; Dunlea, A. G.; Higgins, J. A.

    2016-12-01

    Despite its importance as a major sink for seawater K and Mg, estimates of clay authigenesis in marine sediments remain poorly constrained. Previous work on Mg isotope fractionation during clay formation has revealed a preferential uptake of 26Mg, yielding authigenic clay products with potentially distinct δ26Mg compared to the detrital component. In a similar manner, we aim to quantify the K isotope fractionation during authigenic clay formation and to use paired δ26Mg and δ41K measurements as proxies for the identification and quantification of authigenic clays in shallow and deep marine sedimentary systems. To better understand the behavior of paired Mg and K isotopes during authigenic clay formation in marine sediments, we measured δ26Mg and δ41K values of pore-fluids and sediments from ODP/IODP sites 1052, U1395, U1403 and U1366. We find that while pore-fluid K concentrations at sites 1052, U1395 and U1403 all decline with depth, δ41K profiles differ significantly. These differences might be a result of a complex interplay between clay authigenesis, sedimentation rate, and fractionation of K isotopes during diffusion. Results from 1-D diffusion-advection-reaction models suggest that, in contrast to Mg, diffusion may play an important role in determining the overall K isotope fractionation during clay authigenesis in sites with low-sedimentation rates. Sites with high sedimentation rates may act as close systems where diffusion is negligible. In such cases, K uptake can be modeled as a Rayleigh distillation process and K isotope fractionation can be estimated. Measurements of δ26Mg and δ41K of pore-fluids from site U1395 and bulk sediments from U1366 suggest that paired measurements of these isotopic systems in siliciclastic marine sediments can provide new insights into rates of marine clay authigenesis, a globally important but understudied component of many geochemical cycles.

  6. Evapotranspiration partitioning through in-situ oxygen isotope measurements in an oasis cropland

    NASA Astrophysics Data System (ADS)

    Wen, Xue-Fa

    2016-04-01

    The oxygen isotope compositions of ecosystem water pools and fluxes are useful tracers in the water cycle. As part of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) program, high-frequency and near-continuous in situ measurements of 18O composition of atmospheric vapor (δv) and of evapotranspiration (δET) were made with the flux-gradient method using a cavity ring-down spectroscopy water vapor isotope analyzer. At the sub-daily scale, we found, in conjunction with intensive isotopic measurements of other ecosystem water pools, that the differences between 18O composition of transpiration (δT) and of xylem water (δx) were negligible in early afternoon (13:00-15:00 Beijing time) when ET approached the daytime maximum, indicating isotopic steady state. At the daily scale, for the purpose of flux partitioning, δT was approximated by δx at early afternoon hours, and the 18O composition of soil evaporation (δE) was obtained from the Craig-Gordon model with a moisture-dependent soil resistance. The relative contribution of transpiration to evapotranspiration ranged from 0.71 to 0.96 with a mean of 0.87 ± 0.052 for the growing season according to the isotopic labeling, which was good agreement with soil lysimeter measurements showing a mean transpiration fraction of 0.86 ± 0.058. At the growing season scale, the predicted18O composition of runoff water was within the range of precipitation and irrigation water according to the isotopic mass conservation. The 18O mass conservation requires that the decreased δ18O of ET should be balanced by enhanced δ18O of runoff water. (Wen, XF*, Yang, B, Sun, XM, Lee, X. 2015. Evapotranspiration partitioning through in-situ oxygen isotope measurements in an oasis cropland. Agricultural and Forest Meteorology , doi:10.1016/j.agrformet.2015.12.003).

  7. Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

    USGS Publications Warehouse

    Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.

    2007-01-01

    The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different

  8. An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, T.; Bühler, F.; Koppmann, R.; Krebsbach, M.

    2015-10-01

    Stable isotope measurements in atmospheric volatile organic compounds (VOCs) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOCs in ambient air have mainly focussed on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOCs. This system, consisting of a gas chromatography pyrolysis isotope ratio mass spectrometer (GC-P-IRMS) and a pre-concentration system, was thoroughly characterised using a VOC test mixture. A precision of better than 9 ‰ (in δ 2H) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene and n-octane. Above a minimum required pre-concentrated compound mass the obtained δ 2H values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOCs at ambient levels is demonstrated with measurements of outside air on 5 different days in February and March 2015. The measured hydrogen isotope ratios range from -136 to -105 ‰ forn-pentane, from -86 to -63 ‰ for toluene, from -39 to -15 ‰ for ethylbenzene, from -99 to -68 ‰ for m/p-xylene and from -45 to -34 ‰ for o-xylene.

  9. An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, T.; Bühler, F.; Koppmann, R.; Krebsbach, M.

    2015-07-01

    Stable isotope measurements in atmospheric volatile organic compounds (VOC) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOC in ambient air mainly focus on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOC. This system consisting of a GC-P-IRMS (Gas Chromatography Pyrolysis Isotope Ratio Mass Spectrometer) and a preconcentration system was thoroughly characterised using a working standard. A precision of better than 9 ‰ (in δD) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene, and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene, and n-octane. Above a compound specific minimum peak area the obtained δD values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOC at ambient levels is demonstrated with measurements of outside air on five different days in February and March 2015. The measured hydrogen isotope ratios range from -136 to -105 ‰ for n-pentane, from -86 to -63 ‰ for toluene, from -39 to -15 ‰ for ethylbenzene, from -99 to -68 ‰ for m/p-xylene, and from -45 to -34 ‰ for o-xylene.

  10. High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.

    PubMed

    Paul, Maxence; Bridgestock, Luke; Rehkämper, Mark; van DeFlierdt, Tina; Weiss, Dominik

    2015-03-10

    A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a (207)Pb-(204)Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28±21 pg (1sd) and typical Pb recoveries of 40-60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12±4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700-1500 ppm and 1000-2000 ppm were achieved for (207)Pb/(206)Pb, (208)Pb/(206)Pb and (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor (204)Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the (206)Pb/(204)Pb ratios are well correlated

  11. Measurement of stable carbon isotope ratios of non-methane hydrocarbons and halocarbons

    NASA Astrophysics Data System (ADS)

    Zuiderweg, A. T.

    2012-09-01

    Within the realm of volatile organic compounds, hydrocarbons and halocarbons form a sizable proportion of carbon input to the atmosphere. Within these compound categories, the light non-methane hydrocarbons (NMHC, two to seven carbon atoms) and monocarbon halocarbons have a special place as these have strong, if not exclusive, anthropogenic (human-caused) sources. With common atmospheric molar mixing ratios in the parts-per-trillion (10-12 mole/mole) to parts-per-billion (10-9 mole/mole) range, these trace gases, though decidedly minor constituants of the atmosphere, have diverse consequences due to their atmospheric presence and their removal processes. Effects range from causing ground level air pollution and resulting hazards to health, to contributing to anthropogenic climate change and the destruction of the ozone layer in the stratosphere, among many others. The existance of stable isotopes (otherwise identical atoms with varying amounts of neutrons that do not spontaneously disintegrate) in several elements relevant to atmospheric chemistry and physics is a boon to research. Their presence in molecules is detectable by mass and cause small intra- and intermolecular property changes. These changes range from the physical (e.g. boiling point variation) to the chemical (reaction rate variation) and can influence external interactions as well. The measurement of the ratio of a minor stable isotope of an element to the major one (the stable isotope ratio) can be used to establish source fingerprints, trace the interaction dynamics, and refine the understanding of the relative contribution of sources and sinks to the atmosphere as a whole. The stable minor stable isotope of carbon, 13C, has a natural abundance of approximately 1.1 %. It has a sufficient fractional mass difference from its major isotope as to cause significant effects, making it ideal for measuring the ratios and properties of hydro- and halocarbons. In order to enable a better understanding of the

  12. Uranium Isotopic Ratio Measurements of U3O8 Reference Materials by Atom Probe Tomography

    SciTech Connect

    Fahey, Albert J.; Perea, Daniel E.; Bartrand, Jonah AG; Arey, Bruce W.; Thevuthasan, Suntharampillai

    2016-01-01

    We report results of measurements of isotopic ratios obtained with atom probe tomography on U3O8 reference materials certified for their isotopic abundances of uranium. The results show good agreement with the certified values. High backgrounds due to tails from adjacent peaks complicate the measurement of the integrated peak areas as well as the fact that only oxides of uranium appear in the spectrum, the most intense of which is doubly charged. In addition, lack of knowledge of other instrumental parameters, such as the dead time, may bias the results. Isotopic ratio measurements can be performed at the nanometer-scale with the expectation of sensible results. The abundance sensitivity and mass resolving power of the mass spectrometer are not sufficient to compete with magnetic-sector instruments but are not far from measurements made by ToF-SIMS of other isotopic systems. The agreement of the major isotope ratios is more than sufficient to distinguish most anthropogenic compositions from natural.

  13. High-Frequency Isotope Measurements in Nitrous Oxide by Using Mid-Ir Laser Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dong, F.; Baer, D. S.

    2010-12-01

    The stable isotope composition of atmosphere trace gases provides information of their origin and fate that cannot be determined from their concentration measurements alone. Biological source and loss processes, like bacterial production of N2O, are typically accompanied by isotopic selectivity associated with the kinetics of bond formation and destruction. Of the three important biologically mediated greenhouse gases (CO2, CH4 and N2O), the understanding of N2O isotopic budget in air lags far behind the other two gases. One of the reasons of this is due to the low concentration of N2O in ambient air (~320 ppbv), which leads to inherent difficulties in collection, extraction and analysis. We report on the development of novel instrumentation for real-time measurements of nitrogen-isotope ratio (δ15N) and mixing ratio [N2O] of nitrous oxide over a very wide range of mixing ratios. This novel technology, which employs cavity enhanced absorption and a mid-infrared laser and does not require any cryogenic components, has been developed for in situ simultaneous measurements of the mixing ratios of three main isotopomers - 14N14N16O, 15N14N16O and 14N15N16O, which leads to the nitrogen-isotope ratio (δ15N) and the 15N position-dependent enrichment. A precision of better than 1 per mil may be achieved in ambient air (300 ppbv N2O) in less than 300 seconds measurement time.

  14. Water stable isotope shifts of surface waters as proxies to quantify evaporation, transpiration and carbon uptake on catchment scales

    NASA Astrophysics Data System (ADS)

    Barth, Johannes; van Geldern, Robert; Veizer, Jan; Karim, Ajaz; Freitag, Heiko; Fowlwer, Hayley

    2017-04-01

    Comparison of water stable isotopes of rivers to those of precipitation enables separation of evaporation from transpiration on the catchment scale. The method exploits isotope ratio changes that are caused exclusively by evaporation over longer time periods of at least one hydrological year. When interception is quantified by mapping plant types in catchments, the amount of water lost by transpiration can be determined. When in turn pairing transpiration with the water use efficiency (WUE i.e. water loss by transpiration per uptake of CO2) and subtracting heterotrophic soil respiration fluxes (Rh), catchment-wide carbon balances can be established. This method was applied to several regions including the Great Lakes and the Clyde River Catchments ...(Barth, et al., 2007, Karim, et al., 2008). In these studies evaporation loss was 24 % and 1.3 % and transpiration loss was 47 % and 22 % when compared to incoming precipitation for the Great Lakes and the Clyde Catchment, respectively. Applying WUE values for typical plant covers and using area-typical Rh values led to estimates of CO2 uptake of 251 g C m-2 a-1 for the Great Lakes Catchment and CO2 loss of 21 g C m2 a-1 for the Clyde Catchment. These discrepancies are most likely due to different vegetation covers. The method applies to scales of several thousand km2 and has good potential for improvement via calibration on smaller scales. This can for instance be achieved by separate treatment of sub-catchments with more detailed mapping of interception as a major unknown. These previous studies have shown that better uncertainty analyses are necessary in order to estimate errors in water and carbon balances. The stable isotope method is also a good basis for comparison to other landscape carbon balances for instance by eddy covariance techniques. This independent method and its up-scaling combined with the stable isotope and area-integrating methods can provide cross validation of large-scale carbon budgets

  15. A new route for length measurement by phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Luo, ZhiYong; Li, ZhangHong

    2012-04-01

    By the mathematic models of flexible hinge, the accurate relationship between the phase-shifting and pressure acting on the hinge is deduced and verified by experimental results. Through the optimization of the geometric parameter of flexible hinge, a phase-shifting generator is developed to determine the length of an object precisely by interferometry. The experiments show that the triple phase-shifting produced using this generator is up to 1 μm. With this generator, an example for the application in length measurement is introduced. The result shows the length uncertainty is 0.5 nm when the temperature uncertainty is limited in 2 mK. This paper provides a novel technique to measure the dimension of an object, especially to the diameter of a silicon sphere for Avogadro constant project.

  16. Opaque optics thickness measurement using a cyclic path optical configuration setup and polarization phase shifting interferometry.

    PubMed

    Kumar, Y Pavan; Chatterjee, Sanjib

    2012-03-20

    Thickness measurement of an opaque optics using a cyclic path optical configuration (CPOC) setup and polarization phase shifting interferometry (PPSI) is presented. The CPOC setup is used to simultaneously focus two orthogonally polarized counterpropagating converging beams at its hypotenuse arm. The opaque optics is placed at the hypotenuse arm of the CPOC setup such that one of its surfaces reflects back one of the counterpropagating focusing beams. Because of the thickness of the opaque optics, the other focusing beam suffers a longitudinal shift in the beam focus. Applying PPSI, the longitudinal shift in the beam focus which is twice the thickness of the opaque optics is determined. The results obtained for a silicon plate of thickness 0.660 mm with a measurement uncertainty of 0.013 mm are presented. © 2012 Optical Society of America

  17. X-ray phase-shifts-based method of volumetric breast density measurement.

    PubMed

    Wu, Xizeng; Yan, Aimin; Liu, Hong

    2012-07-01

    The high breast density is one of the biggest risk factors for breast cancer. Identifying patient having persistent high breast density is important for breast cancer screening and prevention. In this work the authors propose for the first time an x-ray phase-shifts-based method of breast density measurement. When x ray traverses the breast, x ray gets not only its intensity attenuated but also its phase shifted. Studying the x-ray phase-shifts generated by the breast tissues, we derived a general formula for determining the volumetric breast density from the breast phase map. The volumetric breast density is reconstructed by retrieving the breast phase map from just a single phase-sensitive projection of the breast, through the use of an innovative phase retrieval method based on the phase-attenuation duality. In order to numerically validate this phase-shifts-based method for measuring the volumetric breast density, the authors performed computer simulations with a digitally simulated anthropomorphic breast phantom. Using the proposed phase-shifts-based method, we reconstructed the breast phantom's volumetric breast density, which differs from the phantom's intrinsic breast density by only 0.06%. In the presence of noises in the projection image, the reconstructed volumetric breast density differs from the phantom's intrinsic breast density by only 1.79% for a projection signal-to-noise-ratio (SNR) of 34. The error in reconstructed breast density is further reduced to 1.61% and 1.55% for SNR = 68 and SNR = 134, respectively, achieving good accuracies in the breast density determination. The authors proposed an x-ray phase-shifts-based method of measuring the volumetric breast density. The simulation results numerically validated the proposed method as a novel method of breast density measurement with good accuracies. © 2012 American Association of Physicists in Medicine.

  18. The time-shift technique for measurement size of non-transparent spherical particles

    NASA Astrophysics Data System (ADS)

    Schäfer, Walter; Tropea, Cameron

    2014-08-01

    In this study we introduce the time-shift technique, also known as the pulsed-displacement technique, as a means of measuring size and velocity of spherical particles. The measurement technique is not new, it has been introduced by Semidetnov[1] in 1985 and more generally discussed by Hess and Wood[2], Lin et al[3], Damaschke et al.[4] and Albrecht et al[5]. The novelty introduced in this study is the application of the technique to measure non-transparent particles, which are quite common for example in spray drying processes or in paint sprays. In this contribution the basic working principle of the time-shift technique will be reviewed and an optical configuration suitable for the measurement of non-transparent droplets will be presented. The signal generation and processing will be discussed. Example measurements in a milk spray are presented.

  19. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  20. Distinguishing phosphate from fertilizers and wastewater treatment plant effluents in Western Canada using oxygen isotope measurements

    NASA Astrophysics Data System (ADS)

    Fau, Veronique; Nightingale, Michael; Tamburini, Frederica; Mayer, Bernhard

    2014-05-01

    The successful application of oxygen isotope ratios as a tracer for phosphate in aquatic ecosystems requires that different sources of phosphate are isotopically distinct. The objective of this study was to determine whether the oxygen isotope ratios of phosphate from fertilizers and effluents from wastewater treatment plants in Western Canada are isotopically distinct. Therefore, we carried out oxygen isotope analyses on phosphate in effluent from five different wastewater treatment plants (WWTP) in the Bow River watershed of Alberta, Canada. Samples were collected directly from the final effluent (post-UV) in Banff and Canmore upstream of Calgary, and from effluents of Calgary's WWTPs at Bonnybrook, Fish Creek and Pine Creek. We also carried out oxygen isotope analyses on a variety of phosphate-containing fertilizers that are widely used in Western Canada. Historically, most of the phosphate contained in manufactured fertilizers sold in Alberta came from two distinct deposits: 1) a weathered Pliocene igneous carbonatite located in eastern Canada, and 2) the Permian Phosphoria Formation in the western USA. Phosphate (PO43-) contained in the water or the fertilizer was concentrated and quantitatively converted to pure silver phosphate (Ag3PO4). The silver phosphate was then reduced with carbon in an oxygen free environment using a TC/EA pyrolysis reactor linked to a mass spectrometer where 18O/16O ratios of CO were measured in continuous flow mode. Preparation of samples for δ18OPO4 analyses was conducted using the Magnesium Induced Coprecipitation (MAGIC) method. Expected oxygen isotope ratios for phosphate in equilibrium with water (δ18Oeq) were calculated using the Longinelli and Nuti equation: T (° C) = 111.4 - 4.3 (δ18Oeq - δ18Owater). Measured δ18O values of phosphate for fertilizer samples varied from 8 to 25 oÈ®n average, fertilizer samples of sedimentary origin had higher δ18O values (15.8) than those of igneous origin (11.5). Phosphate isotopic

  1. VAPOR PRESSURE ISOTOPE EFFECTS IN THE MEASUREMENT OF ENVIRONMENTAL TRITIUM SAMPLES.

    SciTech Connect

    Kuhne, W.

    2012-12-03

    Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The magnitude of the vapor pressure isotope effect is characterized as functions of the amount of water distilled from the sample aliquot and the heat settings for the distillation process. The tritium concentration in the distillate is higher than the tritium concentration in the sample early in the distillation process, it then sharply decreases due to the vapor pressure isotope effect and becomes lower than the tritium concentration in the sample, until the high tritium concentration retained in the boiling flask is evaporated at the end of the process. At that time, the tritium concentration in the distillate again overestimates the sample tritium concentration. The vapor pressure isotope effect is more pronounced the slower the evaporation and distillation process is conducted; a lower heat setting during the evaporation of the sample results in a larger bias in the tritium measurement. The experimental setup used and the fact that the current study allowed for an investigation of the relative change in vapor pressure isotope effect in the course of the distillation process distinguish it from and extend previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.034 {+-} 0.033, 1.052 {+-} 0.025, and 1.066 {+-} 0.037, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples, this implies that

  2. SERTS-95 Measurements of Wavelength Shifts in Coronal Emission Lines Across a Solar Active Region

    NASA Technical Reports Server (NTRS)

    Brosius, Jeffery W.; Thomas, Roger; Davila, Joseph

    1999-01-01

    We used slit spectra from the 1995 flight of Goddard Space Flight Center's Solar EUV Rocket Telescope and Spectrograph (SERTS-95) to measure wavelength shifts of coronal emission lines in the core of NOAA active region 7870 relative to its immediate surroundings (its "edge"). This method circumvents the unavailability of reliable laboratory rest wavelengths for the observed lines by using wavelengths from the edge spectrum as references. We derived the, SERTS-95 wavelength calibration from measurements of a post-flight laboratory spectrum containing 28 He II and Ne II EUV standard wavelengths known to high accuracy. Wavelength measurements for lines of He I, Ne III, and additional lines of Ne II in the laboratory calibration spectrum provide more accurate values than were previously available, enabling these lines also to serve as future calibration standards. Six solar lines were chosen for this study, namely, He II at 303.78 A, Fe XII at 193.51 A, Fe XIII at 202.05 A, Fe XIV at 211.33 A, Fe XV at 284.15 A, and Fe XVI at 335.41 A. Because these lines are free from known blends in the SERTS-95 spectra and are either intrinsically strong or near the SERTS-95 peak sensitivity, they are our most reliable lines for measuring relative wavelength shifts in the spatially resolved active region core spectra. The iron ions are the hottest ions ever used for this type of analysis. All six lines reveal statistically significant spatial variations in their measured relative wavelength shifts in the active region core, including mixtures of blueshifts and redshifts (each with maximum values corresponding to relative Doppler velocities approximately 15 km/s), indicating a dynamic, turbulent corona. For each of these lines we calculated weighted-average relative Doppler velocities from the wavelength shifts in the spatially resolved core spectra by weighting the shifts in the individual spatial pixels with their respective measurement uncertainties.

  3. New Measurements of the Li, Be, and B Isotopes as a Test of Cosmic Ray Transport Models

    NASA Technical Reports Server (NTRS)

    deNolfo, Georgia A.; Yanasak, N. E.; Binns, W. R.; Cummings, A. C.; Davis, A. J.; George, J. S.; Hink, P. L.; Israel, M. H.; Leske, R. A.; Mewaldt, R. A.

    2003-01-01

    Precise measurements of predominantly secondary cosmic-ray Li, Be, and B together with current well-measured production cross-sections for these isotopes help to improve our understanding of galactic cosmic ray propagation models. The Cosmic Ray Isotope Spectrometer (CRIS) on ACE has been measuring isotopic composition of cosmic rays since 1997 with high statistical precision. We present the isotopic abundances from CRIS and discuss these observations in the context of cosmic-ray transport models and previous cosmic-ray measurements.

  4. ac Stark shift measurements of the clock transition in cold Cs atoms: Scalar and tensor light shifts of the D2 transition

    NASA Astrophysics Data System (ADS)

    Costanzo, G. A.; Micalizio, S.; Godone, A.; Camparo, J. C.; Levi, F.

    2016-06-01

    The ac Stark shift, or light shift, is a physical phenomenon that plays a fundamental role in many applications ranging from basic atomic physics to applied quantum electronics. Here, we discuss experiments testing light-shift theory in a cold-atom cesium fountain clock for the Cs D2 transition (i.e., 6 2S1 /2→6 2P3 /2 at 852 nm). Cold-atom fountains represent a nearly ideal system for the study of light shifts: (1) The atoms can be perturbed by a field of arbitrary character (e.g., coherent field or nonclassical field); (2) there are no trapping fields to complicate data interpretation; (3) the probed atoms are essentially motionless in their center-of-mass reference frame, T ˜ 1 μK; and (4) the atoms are in an essentially collisionless environment. Moreover, in the present work the resolution of the Cs excited-state hyperfine splittings implies that the D2 ac Stark shift contains a nonzero tensor polarizability contribution, which does not appear in vapor phase experiments due to Doppler broadening. Here, we test the linearity of the ac Stark shift with field intensity, and measure the light shift as a function of field frequency, generating a "light-shift curve." We have improved on the previous best test of theory by a factor of 2, and after subtracting the theoretical scalar light shift from the experimental light-shift curves, we have isolated and tested the tensor light shift for an alkali D2 transition.

  5. 30 CFR 72.800 - Single, full-shift measurement of respirable coal mine dust.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... coal mine dust. 72.800 Section 72.800 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH HEALTH STANDARDS FOR COAL MINES Miscellaneous § 72.800 Single, full-shift measurement of respirable coal mine dust. The Secretary will use a single,...

  6. Carbon and Hydrogen Isotope Measurements of Alcohols and Organic Acids by Online Pyroprobe-GC-IRMS

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

    2012-01-01

    The detection of methane in the atmosphere of Mars, combined with evidence showing widespread water-rock interaction during martian history, suggests that the production of methane on Mars may be the result of mineral surface-catalyzed CO2 and or CO reduction during Fisher-Tropsch Type (FTT) reactions. A better understanding of these reaction pathways and corresponding C and H isotope fractionations is critical to deciphering the synthesis of organic compounds produced under abiotic hydrothermal conditions. Described here is a technique for the extraction and analysis of both C and H isotopes from alcohols (C1-C4) and organic acids (C1-C6). This work is meant to provide a "proof of concept" for making meaningful isotope measurements on complex mixtures of solid-phase hydrocarbons and other intermediary products produced during high-temperature and high-pressure synthesis on mineral-catalyzed surfaces. These analyses are conducted entirely "on-line" utilizing a CDS model 5000 Pyroprobe connected to a Thermo Trace GC Ultra that is interfaced with a Thermo MAT 253 isotope ratio mass spectrometer operating in continuous flow mode. Also, this technique is designed to carry a split of the GC-separated product to a DSQ II quadrupole mass spectrometer as a means of making semi-quantitative compositional measurements. Therefore, both chemical and isotopic measurements can be carried out on the same sample.

  7. Simultaneous measurement of 13C- and 15N-isotopic enrichments of threonine by mass spectrometry.

    PubMed

    Godin, Jean-Philippe; Mermoud, Anne-France; Rémond, Didier; Faure, Magali; Breuille, Denis; Williamson, Gary; Peré-Trepat, Emma; Ramadan, Ziad; Fay, Laurent-Bernard; Kochhar, Sunil

    2009-04-01

    Under conditions of high isotopic dilution, e.g. in a tracer study, the ability to determine accurately and quantitatively small variations in isotopic enrichments of differently labelled chemical compounds (e.g. (13)C and (15)N in threonine) in a single run by gas chromatography/mass spectrometry (GC/MS) is desirable but remains a technological challenge. Here, we report a new, rapid and simple GC/MS method for simultaneously measuring the isotopic enrichments of doubly labelled threonine ([U(13)C] and (15)N) with isotopic enrichment lower than 1.5 Molar Percent Excess (MPE). The long-term reproducibility measured was around 0.09 MPE for both tracers (throughout a 6 week period). The intra-day repeatability was lower than 0.05 and 0.06 MPE for [U(13)C]-Thr and (15)N-Thr, respectively. To calculate both isotopic enrichments, two modes of calculations were used: one based on work by Rosenblatt et al. in 1992 and the other one using a matrix approach. Both methods gave similar results (ANOVA, P >0.05) with close precision for each mode of calculation. The GC/MS method was then used to investigate the differential utilization of threonine in different organs according to its route of administration in minipigs after administration of both tracers. In plasma samples, the lowest isotopic enrichment measured between two successive time points was at 0.01 and 0.02 MPE for [U(13)C]-Thr and (15)N-Thr, respectively. Moreover, the accuracy of GC/MS (13)C-isotopic enrichment measured was validated by analyzing the same plasma samples by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Statistical analysis showed that both techniques gave the same results (ANOVA, P >0.05). This new GC/MS method offers the possibility to measure (13)C- and (15)N-isotopic enrichments with higher throughput, and using a lower amount of sample, than using GC/C/IRMS.

  8. Mass measurements of short-lived isotopes in a penning trap

    SciTech Connect

    Kern, F.; Egelhof, P.; Hilberath, T.; Kalinowsky, H.; Kluge, H.h.; Kunz, K.; Schweikhard, L.; Stolzenberg, H.; Moore, R.B.; Audi, G.; and others

    1987-12-10

    A mass spectrometer has been set up at the on-line isotope separator ISOLDE at CERN/Geneva. Mass-separated radioactive ions are stored in a Penning trap. Their mass is determined by a measurement of the cyclotron frequency in the magnetic field of a superconducting magnet. A resolving power of up to 300.000 and a precision of some 10 keV were determined in case of mass measurements of neutron-deficient RB and Cs isotopes. The resonance of the isobars /sup 88/Sr and /sup 88/Rb were clearly resolved and evidence was obtained for an isomer in /sup 122/Cs.

  9. Measurement of the J = 0-1 rotational transitions of three isotopes of ArD(+)

    NASA Technical Reports Server (NTRS)

    Bowman, W. C.; Plummer, G. M.; Herbst, E.; De Lucia, F. C.

    1983-01-01

    The rotational transitions of all three isotopic species of ArD(+) in samples containing the Ar isotopes in their natural abundances have been measured by means of millimeter and submillimeter techniques that employ a magnetically enhanced abnormal glow discharge. All three transition frequency measurements were made from digitally averaged signals detected through a lock-in amplifier with a 10-msec time constant. The Ar-4OD(+) transition was easily visible in real time on an oscilloscope with SNR of about 15. It is noted that the observed transition of Ar-38D(+) is more than five orders of magnitude weaker than that due to HCO(+).

  10. Improving precision in resonance ionization mass spectrometry : influence of laser bandwidth in uranium isotope ratio measurements.

    SciTech Connect

    Isselhardt, B. H.; Savina, M. R.; Knight, K. B.; Pellin, M. J.; Hutcheon, I. D.; Prussin, S. G.

    2011-03-01

    The use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of {sup 235}U/{sup 238}U ratios by resonance ionization mass spectrometry (RIMS) to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a three-color, three-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from 10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation.

  11. Precipitation water stable isotope measurements and analyses in Middle and Polar Ural

    NASA Astrophysics Data System (ADS)

    Stukova, Olga; Gribanov, Konstantin; Zakharov, Vyacheslav; Cattani, Olivier; Jouzel, Jean

    2015-11-01

    In this paper, we present results of precipitation (rain, snow) water stable isotope measurements, which were collected on two places. Measuring was made on laser spectroscopy analyzer PICARRO L2130-i equipped with liquid auto sampler. We describe method of sample collecting, preparing, measuring and continuing analysis of experimental data. Stored data include results of 177 samples measuring from Kourovka collected from November 2012 to March 2014 and 73 samples from Labytnangi collected from March 2013 to December 2013.

  12. Ocular Measures of Sleepiness Are Increased in Night Shift Workers Undergoing a Simulated Night Shift Near the Peak Time of the 6-Sulfatoxymelatonin Rhythm

    PubMed Central

    Ftouni, Suzanne; Sletten, Tracey L.; Nicholas, Christian L.; Kennaway, David J.; Lockley, Steven W.; Rajaratnam, Shantha M.W.

    2015-01-01

    Study Objectives: The study examined the relationship between the circadian rhythm of 6-sulphatoxymelatonin (aMT6s) and ocular measures of sleepiness and neurobehavioral performance in shift workers undergoing a simulated night shift. Methods: Twenty-two shift workers (mean age 33.4, SD 11.8 years) were tested at approximately the beginning (20:00) and the end (05:55) of a simulated night shift in the laboratory. At the time point corresponding to the end of the simulated shift, 14 participants were classified as being within range of 6-sulphatoxymelatonin (aMT6s) acrophase— defined as 3 hours before or after aMT6s peak—and 8 were classified as outside aMT6s acrophase range. Participants completed the Karolinska Sleepiness Scale (KSS) and the auditory psychomotor vigilance task (aPVT). Waking electroencephalography (EEG) was recorded and infrared reflectance oculography was used to collect ocular measures of sleepiness: positive and negative amplitude/velocity ratio (PosAVR, NegAVR), mean blink total duration (BTD), the percentage of eye closure (%TEC), and a composite score of sleepiness levels (Johns Drowsiness Scale; JDS). Results: Participants who were tested within aMT6s acrophase range displayed higher levels of sleepiness on ocular measures (%TEC, BTD, PosAVR, JDS), objective sleepiness (EEG delta power frequency band), subjective ratings of sleepiness, and neurobehavioral performance, compared to those who were outside aMT6s acrophase range. Conclusions: The study demonstrated that objective ocular measures of sleepiness are sensitive to circadian rhythm misalignment in shift workers. Citation: Ftouni S, Sletten TL, Nicholas CL, Kennaway DJ, Lockley SW, Rajaratnam SM. Ocular measures of sleepiness are increased in night shift workers undergoing a simulated night shift near the peak time of the 6-sulfatoxymelatonin rhythm. J Clin Sleep Med 2015;11(10):1131–1141. PMID:26094925

  13. Methods of measuring frequency shifts in the interference structure of the sound field in oceanic waveguides

    NASA Astrophysics Data System (ADS)

    Kuz'kin, V. M.; Pereselkov, S. A.

    2010-07-01

    The efficiency of the correlation method is considered as applied to measuring frequency shifts of maxima in the interference structure of the sound speed under the influence of distortions of the sound-speed profile. The method is based on tracing the position of the maximum of the cross-correlation function corresponding to the spectrum of the transmitted signal in the frequency domain. The distortion is modeled by seasonal variations of the hydrological environment. The noise immunity of the method is analyzed. The correlation method is compared with other known methods of tracing frequency shifts of the interference maxima.

  14. Air-mass flux measurement system using Doppler-shifted filtered Rayleigh scattering

    NASA Technical Reports Server (NTRS)

    Shirley, John A.; Winter, Michael

    1993-01-01

    An optical system has been investigated to measure mass flux distributions in the inlet of a high speed air-breathing propulsion system. Rayleigh scattered light from air is proportional to the number density of molecules and hence can be used to ascertain the gas density in a calibrated system. Velocity field measurements are achieved by spectrally filtering the elastically-scattered Doppler-shifted light with an absorbing molecular filter. A novel anamorphic optical collection system is used which allows optical rays from different scattering angles, that have different Doppler shifts, to be recorded separately. This is shown to obviate the need to tune the laser through the absorption to determine velocities, while retaining the ability to make spatially-resolved measurements along a line. By properly selecting the laser tuning and filter parameters, simultaneous density measurements can be made. These properties are discussed in the paper and experiments demonstrating the velocimetry capability are described.

  15. Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method

    USGS Publications Warehouse

    Casciotti, K.L.; Sigman, D.M.; Hastings, M. Galanter; Böhlke, J.K.; Hilkert, A.

    2002-01-01

    We report a novel method for measurement of the oxygen isotopic composition (18O/16O) of nitrate (NO3-) from both seawater and freshwater. The denitrifier method, based on the isotope ratio analysis of nitrous oxide generated from sample nitrate by cultured denitrifying bacteria, has been described elsewhere for its use in nitrogen isotope ratio (15N/14N) analysis of nitrate.1Here, we address the additional issues associated with 18O/16O analysis of nitrate by this approach, which include (1) the oxygen isotopic difference between the nitrate sample and the N2O analyte due to isotopic fractionation associated with the loss of oxygen atoms from nitrate and (2) the exchange of oxygen atoms with water during the conversion of nitrate to N2O. Experiments with 18O-labeled water indicate that water exchange contributes less than 10%, and frequently less than 3%, of the oxygen atoms in the N2O product for Pseudomonas aureofaciens. In addition, both oxygen isotope fractionation and oxygen atom exchange are consistent within a given batch of analyses. The analysis of appropriate isotopic reference materials can thus be used to correct the measured 18O/16O ratios of samples for both effects. This is the first method tested for 18O/16O analysis of nitrate in seawater. Benefits of this method, relative to published freshwater methods, include higher sensitivity (tested down to 10 nmol and 1 μM NO3-), lack of interference by other solutes, and ease of sample preparation.

  16. Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

    PubMed

    Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T

    2013-03-01

    Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

  17. Interchange for Joint Research Entitled: Miniature Laser Spectrometer for Stable Isotope Measurements

    NASA Technical Reports Server (NTRS)

    Becker, J. F.; Kojiro, D. R.

    1999-01-01

    As a first step in successfully measuring carbon isotopes optically we have previously demonstrated the measurement of C-13/C-12 to a precision of 0.1% using a tunable diode laser and CO2 spectral lines in the 2300/cm spectral region. This precision of 0.1% (1 per mil) for carbon isotopes is a value sufficiently precise to provide important isotopic data of interest to astrobiologists. The precision presently attainable in gases is sufficient to permit our instrument to be used in the measurement of isotopic ratios of interest to astrobiologists as well as geologists and planetary scientists. A small stable isotope laser spectrometer with a 10 cm path gas cell was designed and constructed. The cell was integrated with a liquid nitrogen cooled tunable diode laser and indium antimonide detector for evaluation. Using the small gas cell, preliminary measurements of 13C/12C in CO2 were made employing single-beam sequential acquisitions of the required spectral data. The results indicate an accuracy of 0.1% which is sufficiently high to make meaningful measurements of martian samples. In addition, improvements in the spectrometer gas handling system have been made to markedly reduce C-13/C-12 isotopic fractionation during sample gas cell loading which we expect will lead to further improvements in precision and accuracy. An important part of making isotopic ratio measurements in solid samples using diode lasers is the conversion of the elements of interest to molecules that have absorption spectra in the mid-ir spectral range accessible by tunable diode lasers. In this project we have investigated the necessary sample preparation procedures to extract carbon, an element of astrobiological importance, from model soil compounds and to convert it to CO2, a molecule with appropriate optical absorption characteristics for reliable laser spectrometer isotopic ratio measurements of 13C/12C. We have considered calcium carbonate as a model for a component of the martian regolith

  18. Interchange for Joint Research Entitled: Measurement of Stable Nitrogen and Sulfur Isotopes

    NASA Technical Reports Server (NTRS)

    Becker, Joseph F.; Valentin, Jose

    1997-01-01

    Viking measurements of the Martian atmosphere indicate a value of N-15/N-14 which is markedly greater than that found in Earth's atmosphere. These isotopic measurements provide a powerful diagnostic tool which may be used to derive valuable information regarding the past history of Mars and they have been used to place important constraints on the evolution of Mars' atmosphere. Initial partial pressures of nitrogen, outgassing rates, and integrated deposition of nitrogen into minerals have been calculated from this important atmospheric data (McElroy et al., 1976 and 1977; Fox and Dalgarno, 1983). The greater precision obtained in laser spectrometer isotopic measurements compared to the Viking data will greatly improve these calculated values. It has also been proposed that the N-15/N-14 value in Mars' atmosphere has increased monotonically over time (McElroy et al., 1977; Fox and Dalgarno, 1983; Wallis, 1989) owing to preferential escape of atmospheric 14N to space. Nitrogen isotopic ratios might be used to identify relatively ancient crustal rocks (R. Mancinelli, personal communication), and perhaps determine relative aces of surface samples. As a first step in successfully measuring nitrogen isotopes optically we have demonstrated the measurement of 15NI14N to a precision of 0.1% (See Figures 1-4) using a tunable diode laser and an available gas (N-,O) with spectral lines in the 2188 cm-1 region. The sample and reference gas cells contained gases of identical isotopic composition so that the 15NI14N absorption ratio determined from the sample cell, when divided by the 15NI14N absorption ratio determined from the reference cell, should yield an ideal value of unity. The average measured value of this "ratio of ratios" was 0.9983 with a standard deviation (20 values) of 0.0010. This corresponds to a precision of 0.1% (1 per mil) for nitrogen isotopes, a value sufficiently precise to provide important isotopic data of interest to exobiologists. The precision

  19. Eddy Covariance measurements of stable isotopes (δD and δ18O) in water vapor

    NASA Astrophysics Data System (ADS)

    Braden-Behrens, Jelka; Knohl, Alexander

    2017-04-01

    Stable isotopes are a promising tool to enhance our understanding of ecosystem gas exchanges. Studying 18O and 2H in water vapour (H2Ov) can e.g. help partitioning evapotranspiration into its components. With recent developments in laser spectroscopy direct Eddy Covariance (EC) measurements for investigating fluxes of stable isotopologues became feasible. So far very few case studies have applied the EC method to measure stable isotopes in water vapor. We continuously measure fluxes of water vapor isotopologues with the EC method in a managed beech forest in Thuringia, Germany, since autumn 2015 using the following setup: An off-axis integrated cavity output water vapor isotope analyzer (WVIA, Los Gatos Research. Inc, USA) measures the water vapour concentration and its isotopic composition (δD and δ18O). The instrument, that was optimized for high flow rates (app. 4slpm) to generate high frequency (2Hz) measurements, showed sufficient precision with Allan Deviations of app. 0.12 ‰ for δD and 0.06 ‰ for δ18O for averaging periods of 100s. The instrument was calibrated hourly using a high-flow optimized version of the water vapor isotope standard source (WVISS, Los Gatos Research. Inc, USA) that provides water vapor with known isotopic composition for a large range of different concentrations. Our calibration scheme includes a near continuous concentration range calibration instead of a simple 2 or 3-point calibration to face the analyzers strong concentration dependency within a range of app. 6 000 to 16 000 ppm in winter and app. 8 000 to 23 000 ppm in summer. In the used setup, the high-flow and high-frequency optimized water vapor isotope analyzer (WVIA) showed suitable characteristics (Allan deviation and spectral energy distribution) to perform Eddy covariance measurements of stable isotopes in H2Ov. Thus, this novel instrument for EC measurements of water vapor isotopologues provides a new opportunity for studying the hydrological cycle in long

  20. A device for the measurement of residual chemical shift anisotropy and residual dipolar coupling in soluble and membrane-associated proteins

    PubMed Central

    Liu, Yizhou

    2010-01-01

    Residual dipolar coupling (RDC) and residual chemical shift anisotropy (RCSA) report on orientational properties of a dipolar bond vector and a chemical shift anisotropy principal axis system, respectively. They can be highly complementary in the analysis of backbone structure and dynamics in proteins as RCSAs generally include a report on vectors out of a peptide plane while RDCs usually report on in-plane vectors. Both RDC and RCSA average to zero in isotropic solutions and require partial orientation in a magnetic field to become observable. While the alignment and measurement of RDC has become routine, that of RCSA is less common. This is partly due to difficulties in providing a suitable isotopic reference spectrum for the measurement of the small chemical shift offsets coming from RCSA. Here we introduce a device (modified NMR tube) specifically designed for accurate measurement of reference and aligned spectra for RCSA measurements, but with a capacity for RDC measurements as well. Applications to both soluble and membrane anchored proteins are illustrated. PMID:20506033

  1. Isotopic Shift of Atom-Dimer Efimov Resonances in K-Rb Mixtures: Critical Effect of Multichannel Feshbach Physics.

    PubMed

    Kato, K; Wang, Yujun; Kobayashi, J; Julienne, P S; Inouye, S

    2017-04-21

    Multichannel Efimov physics is investigated in ultracold heteronuclear admixtures of K and Rb atoms. We observe a shift in the scattering length where the first atom-dimer resonance appears in the ^{41}K-^{87}Rb system relative to the position of the previously observed atom-dimer resonance in the ^{40}K-^{87}Rb system. This shift is well explained by our calculations with a three-body model including van der Waals interactions, and, more importantly, multichannel spinor physics. With only minor differences in the atomic masses of the admixtures, the shift in the atom-dimer resonance positions can be cleanly ascribed to the isolated and overlapping Feshbach resonances in the ^{40}K-^{87}Rb and ^{41}K-^{87}Rb systems, respectively. Our study demonstrates the role of multichannel Feshbach physics in determining Efimov resonances in heteronuclear three-body systems.

  2. Microbial influences on local carbon isotopic ratios and their preservation in carbonate.

    PubMed

    Sumner, D Y

    2001-01-01

    Analysis of the carbon isotopic composition of carbonates is a valuable tool for studying microbial processes and looking for evidence of life. Microbial fixation of CO2 and conversion of organic carbon to CO2 can produce measurable delta 13C shifts in a microbial mat environment. Diffusion modeling demonstrates that substantial isotopic shifts can develop within the mat and in the diffusion boundary layer in the fluid when CO2 fixation is rapid and prolonged for several hours. Carbonates that precipitate during rapid CO2 fixation can preserve these microbially produced isotopic shifts. However, continued precipitation during intervals when respiration dominates or after the cessation of active microbial growth commonly dilutes autotrophic isotopic signatures. Thus, preserved isotopic signatures rarely reflect the magnitude of isotopic shifts within the mat. Interpretation of observed isotopic shifts in microbial mat carbonate depends on fully characterizing ambient delta 13C and eliminating other origins for isotopic shifts. The carbon isotopic composition of reservoirs can vary substantially, both on Earth and on other planets. Characterizing the reservoir composition and any changes through time is critical to evaluating microbially induced shifts. In addition, careful evaluation of non-microbial causes for shifts in isotopic composition is essential for a reliable interpretation. Complicating processes include recrystallization, calcite precipitation over extended periods of time, variable precipitation rates and water chemistry, and mixing of carbonates having different isotopic signatures.

  3. HORMONE MEASUREMENT GUIDELINES: Tracing lipid metabolism: the value of stable isotopes.

    PubMed

    Umpleby, A Margot

    2015-09-01

    Labelling molecules with stable isotopes to create tracers has become a gold-standard method to study the metabolism of lipids and lipoproteins in humans. There are a range of techniques which use stable isotopes to measure fatty acid flux and oxidation, hepatic fatty synthesis, cholesterol absorption and synthesis and lipoprotein metabolism in humans. Stable isotope tracers are safe to use, enabling repeated studies to be undertaken and allowing studies to be undertaken in children and pregnant women. This review provides details of the most appropriate tracers to use, the techniques which have been developed and validated for measuring different aspects of lipid metabolism and some of the limitations of the methodology. © 2015 Society for Endocrinology.

  4. High resolution measurements of galactic cosmic-ray neon, magnesium, and silicon isotopes

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Spalding, J. D.; Stone, E. C.; Vogt, R. E.

    1980-01-01

    High-resolution measurements of the abundances of individual isotopes of neon, magnesium and silicon in galactic cosmic rays are reported. The Caltech Heavy Isotope Spectrometer Telescope on board the ISEE 3 spacecraft was used to obtain measurements in the range 30 to 180 MeV/n at an rms mass resolution of 0.20 amu. Results indicate excesses of Ne-22 as well as Mg-25 and Mg-26 in galactic cosmic rays with respect to their solar system abundances. Calculations of the effects of interstellar propagation and solar modulation on cosmic-ray isotope abundances also imply an Mg-25 + Mg-26 cosmic ray source fraction significantly greater than the solar system fraction, and it is suggested that the cosmic ray source material and solar system material were synthesized under different conditions.

  5. Isotopic Measurements of Sulphonates and Phosphonates and Investigations of Possible Formaldehyde Products from the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, George

    1996-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope measurements have been made on a homologous series of organic sulfonates discovered in the Murchison meteorite. Mass independent sulfur isotope fractionations were observed along with D/H ratios clearly larger than terrestrial. The sulfur fractionations may be produced chemically and due to molecular symmetry factors. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of molecular clouds. The source of the sulfonate precursors may have been the reactive interstellar molecule, CS. Low temperature CS reactions also produce other sulfur containing compounds as well as a solid phase. Isotopic measurements on bulk phosphonates were also made.

  6. Motion induced phase shifts in MR: acceleration effects in quantitative flow measurements--a reconsideration.

    PubMed

    Kouwenhoven, M; Hofman, M B; Sprenger, M

    1995-06-01

    Magnetic resonance phase difference techniques are commonly used to study flow velocities in the human body. Acceleration is often present, either in the form of pulsatile flow, or in the form of convective acceleration. Questions have arisen about the exact time point at which the velocity is encoded, and also about the sensitivity to (convective) acceleration and higher order motion derivatives. It has become common practice to interpret the net phase shifts measured with a phase difference velocity technique as being the velocity at a certain (Taylor) expansion time point, chosen somewhere between the RF excitation and the echo readout. However, phase shifts are developed over the duration of the encoding magnetic field gradient wave form, and should therefore be interpreted as a more or less time-averaged velocity. It will be shown that the phase shift as measured with a phase difference velocity technique represents the velocity at the "gravity" center of the encoding bipolar gradient (difference) function, without acceleration contribution. Any attempt to interpret the measured phase shift in terms of velocity on any other time point than the gradient gravity point will automatically introduce acceleration sensitivity.

  7. A sensitive, high resolution magic angle turning experiment for measuring chemical shift tensor principal values

    NASA Astrophysics Data System (ADS)

    Alderman, D. W.

    1998-12-01

    A sensitive, high-resolution 'FIREMAT' two-dimensional (2D) magic-angle-turning experiment is described that measures chemical shift tensor principal values in powdered solids. The spectra display spinning-sideband patterns separated by their isotropic shifts. The new method's sensitivity and high resolution in the isotropic-shift dimension result from combining the 5pi magic-angle-turning pulse sequence, an extension of the pseudo-2D sideband-suppression data rearrangement, and the TIGER protocol for processing 2D data. TPPM decoupling is used to enhance resolution. The method requires precise synchronization of the pulses and sampling to the rotor position. It is shown that the technique obtains 35 natural-abundance 13C tensors from erythromycin in 19 hours, and high quality naturalabundance 15N tensors from eight sites in potassium penicillin V in three days on a 400MHz spectrometer.

  8. Resolving vacuum fluctuations in an electrical circuit by measuring the Lamb shift.

    PubMed

    Fragner, A; Göppl, M; Fink, J M; Baur, M; Bianchetti, R; Leek, P J; Blais, A; Wallraff, A

    2008-11-28

    Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental observation of the Lamb shift in a solid-state system. The strong dispersive coupling of a superconducting electronic circuit acting as a quantum bit (qubit) to the vacuum field in a transmission-line resonator leads to measurable Lamb shifts of up to 1.4% of the qubit transition frequency. The qubit is also observed to couple more strongly to the vacuum field than to a single photon inside the cavity, an effect that is explained by taking into account the limited anharmonicity of the higher excited qubit states.

  9. Resolving Vacuum Fluctuations in an Electrical Circuit by Measuring the Lamb Shift

    NASA Astrophysics Data System (ADS)

    Fragner, A.; Göppl, M.; Fink, J. M.; Baur, M.; Bianchetti, R.; Leek, P. J.; Blais, A.; Wallraff, A.

    2008-11-01

    Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental observation of the Lamb shift in a solid-state system. The strong dispersive coupling of a superconducting electronic circuit acting as a quantum bit (qubit) to the vacuum field in a transmission-line resonator leads to measurable Lamb shifts of up to 1.4% of the qubit transition frequency. The qubit is also observed to couple more strongly to the vacuum field than to a single photon inside the cavity, an effect that is explained by taking into account the limited anharmonicity of the higher excited qubit states.

  10. Resolving Vacuum Fluctuations in an Electrical Circuit by Measuring the Lamb Shift

    NASA Astrophysics Data System (ADS)

    Fragner, Andreas; Goppl, Martin; Blais, Alexandre; Wallraff, Andreas

    2009-03-01

    Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental observation of the Lamb shift in a solid-state system. The strong dispersive coupling of a superconducting electronic circuit acting as a quantum bit (qubit) to the vacuum field in a transmission-line resonator leads to measurable Lamb shifts of up to 1.4% of the qubit transition frequency. The qubit is also observed to couple more strongly to the vacuum field than to a single photon inside the cavity, an effect that is explained by taking into account the limited anharmonicity of the higher excited qubit states.

  11. Shift Equivalence of Measures and the Intrinsic Structure of Shocks in the Asymmetric Simple Exclusion Process

    NASA Astrophysics Data System (ADS)

    Derrida, B.; Goldstein, S.; Lebowitz, J. L.; Speer, E. R.

    1998-11-01

    We investigate properties of non-translation-invariant measures, describing particle systems on $\\bbz$, which are asymptotic to different translation invariant measures on the left and on the right. Often the structure of the transition region can only be observed from a point of view which is random---in particular, configuration dependent. Two such measures will be called shift equivalent if they differ only by the choice of such a viewpoint. We introduce certain quantities, called translation sums, which, under some auxiliary conditions, characterize the equivalence classes. Our prime example is the asymmetric simple exclusion process, for which the measures in question describe the microscopic structure of shocks. In this case we compute explicitly the translation sums and find that shocks generated in different ways---in particular, via initial conditions in an infinite system or by boundary conditions in a finite system---are described by shift equivalent measures. We show also that when the shock in the infinite system is observed from the location of a second class particle, treating this particle either as a first class particle or as an empty site leads to shift equivalent shock measures.

  12. Response shift theory: important implications for measuring quality of life in people with disability.

    PubMed

    Schwartz, Carolyn E; Andresen, Elena M; Nosek, Margaret A; Krahn, Gloria L

    2007-04-01

    Measurement of health-related quality of life (HRQOL) in people with disability can be problematic. Ambiguous or paradoxical findings can occur because of differences among people or changes within people regarding internal standards, values, or conceptualization of HRQOL. These "response shifts" can affect standard psychometric indices, such as reliability and validity. Attending to appraisal processes and response shift theory can inform development of HRQOL measures for people with disability that do not confound function and health and that consider important causal indicators such as environment. By design, most HRQOL measures equate function with health, necessarily leading to a lower measured HRQOL in people with functional impairments regardless of their level of self-perceived health. In this article, we present theoretical and conceptual distinctions building on response shift theory and other current developments in HRQOL research. We then submit a set of suggested directions for future measurement development in populations with disabilities that consider these distinctions and extend their use in future measurement developments.

  13. D/H Isotope Ratio Measurements of Atmospheric Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Meisehen, Thomas; Bühler, Fred; Koppmann, Ralf; Krebsbach, Marc

    2015-04-01

    Analysis of isotope ratios in atmospheric volatile organic compounds (VOC) is a reliable method to allocate their sources, to estimate atmospheric residence times and investigate physical and chemical processes on various temporal and spatial scales. Most investigations yet focus on carbon isotope ratios. Certainly more detailed information can be gained by the ratio of deuterium (D) to hydrogen (H) in VOC, especially due to the high mass ratio. Combining measurements of carbon and hydrogen isotopes could lead to considerable improvement in our understanding of atmospheric processes. For this purpose we set up and thoroughly characterised a gas chromatograph pyrolysis isotope ratio mass spectrometer to measure the D/H ratio in atmospheric VOC. From a custom-made gas standard mixture VOC were adsorbed on Tenax®TA which has the advantage that CO2 is not preconcentrated when measuring ambient air samples. Our results show that the pyrolysis method has significant impact on the D/H ratios. A pyrolysis temperature of at least 1723 K and conditioning of the ceramic tube on a regular basis is essential to obtain reproducible D/H isotope ratios. For an independent comparison D/H ratios of the pure VOC used in the gas standard were determined using elemental analysis by Agroisolab (Jülich, Germany). Comparisons of 10 VOC show perfect agreement within the standard deviations of our measurements and the errors given by Agroisolab, e.g. for n-pentane, toluene, 4-methyl-2-pentanone and n-octane. A slight mean difference of 5.1 o was obtained for n-heptane while significant mean differences of 15.5 o and 20.3 o arose for 1,2,4-trimethylbenzene and isoprene, respectively. We further demonstrate the stability of our system and show that the sample preparation does not affect the isotope ratios. Moreover the applicability of our system to ambient air samples is demonstrated.

  14. First Measurements of Osmium Concentration and Isotopic Composition in a Summit, Greenland Ice Core

    NASA Astrophysics Data System (ADS)

    Osterberg, E. C.; Sharma, M.; Hawley, R. L.; Courville, Z.

    2010-12-01

    Osmium (Os) is one of the rarer elements in the environment and therefore one of the most difficult to accurately measure, but its isotopically distinctive crustal, mantle-derived, and extra-terrestrial sources make it a valuable geochemical tracer. Recent state-of-the-art analyses of precipitation, river water, and ocean water samples from around the world have revealed elevated concentrations of Os with a characteristically low (unradiogenic) Os isotopic signature (187Os/188Os). This unusual low Os isotopic signal has been interpreted as evidence for widespread Os pollution due to the smelting of Platinum Group Element (PGE) sulfide ores for use in automobile catalytic converters. However, an environmental time series of Os concentrations and isotopic composition spanning the pre-industrial to modern era has not previously been developed to evaluate changes in atmospheric Os sources through time. Here we present the first measurements of Os concentration and isotopic composition (to our knowledge) in a 100 m-long ice core collected from Summit, Greenland, spanning from ca. 1700 to 2010 AD. Due to the extremely low Os concentrations in snow (10-15 g/g), these analyses have only recently become possible with advances in Thermal Ionization Mass Spectrometry (TIMS) and ultra-clean analytical procedures. Initial results indicate that the 187Os/188Os of Greenland snow was unradiogenic (187Os/188Os = 0.13-0.15) for at least several periods over the past 300 years, including both pre-anthropogenic and modern times. Os concentrations in the Summit ice core are relatively high (11-52 pg/kg) compared to previously measured precipitation in North America, Europe, Asia and Antarctic sea ice (0.35-23 pg/kg). The low (unradiogenic) isotopic composition are consistent with extraterrestrial (cosmic dust and meteorites; 187Os/188Os = 0.13) and possibly volcanic (187Os/188Os = 0.15-0.6) Os sources, although the Os isotopic composition of volcanic emissions is poorly constrained

  15. Fast Scanning Single Collector ICP-MS for Low Level Isotope Ratio Measurements

    NASA Astrophysics Data System (ADS)

    Newman, K.; Georg, B.

    2010-12-01

    Multiple collector (MC)-ICP-MS is recognized as a workhorse in the field of isotope ratio measurements. With its unrivalled precision, high sample throughput and multi-element coverage, MC-ICPMS has opened up new areas of study in earth, environmental and biological sciences. However, SC-ICP-MS is fit for purpose for many applications where sample amount is limited and fractionations are relatively large. To compensate for the inherent ion beam instability associated with the ICP ion source, fast scanning magnetic sector instruments are used. Here, we describe and discuss the use of the Nu Attom SC-ICP-MS for low level isotope ratio measurements. The Nu Attom is a double focusing magnetic sector mass spectrometer with unique fast scanning capabilities. Deflectors located at the entrance and exit of the flight tube are used to alter the effective magnet radius by changing the ion trajectory. This enables a fast electrostatic scan over a mass range of approximately 40%. In contrast to other fast scanning magnetic sector instruments, there is no change in the ion energy which may introduce additional mass bias effects. The Nu Attom also has fully adjustable source and collector slits. This facilitates measurements in medium mass resolution (R=1500-2500), whilst maintaining a flat topped peak necessary for precise isotope ratio measurements. The potential applications of the Nu Attom in isotope ratio measurements will be explored.

  16. Tracing the dispersion of contaminated sediment with plutonium isotope measurements in coastal catchments of Fukushima Prefecture

    NASA Astrophysics Data System (ADS)

    Evrard, Olivier; Pointurier, Fabien; Onda, Yuichi; Chartin, Caroline; Hubert, Amélie; Lepage, Hugo; Pottin, Anne-Claire; Lefèvre, Irène; Bonté, Philippe; Laceby, J. Patrick; Ayrault, Sophie

    2015-04-01

    The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident led to important releases of radionuclides into the environment, and trace levels of plutonium (Pu) were detected in northeastern Japan. However, measurement of Pu isotopic atom and activity ratios is required to differentiate between the contributions of global nuclear test fallout and FDNPP emissions. In this study, we measured Pu isotopic ratios in recently deposited sediments along rivers draining the most contaminated part of the inland radioactive plume. To this end, we carried out a thorough chemical purification and concentration of Pu from sediment samples (5 g dry material) and precise isotopic measurements using a double-focusing sector field ICP-MS. Results showed that the entire range of measured Pu isotopes (i.e., 239Pu, 240Pu, 241Pu, and 242Pu) were detected in all samples, although in extremely low concentrations. The 241Pu/239Pu atom ratios measured in sediment deposits (0.0017-0.0884) were significantly higher than the corresponding values attributed to the global fallout (0.00113±0.00008 on average in the Northern Hemisphere between 31°-71°N). The results indicated the presence of Pu from FDNPP, in slight excess compared to the Pu background from global fallout, representing up to ca. 60% of Pu in the analyzed samples. These results demonstrate that this radionuclide has been transported relatively long distances (45 km) from FDNPP and deposited in rivers representing a potential source of Pu to the ocean.

  17. Achievements in testing of the MGA and FRAM isotopic software codes under the DOE/NNSA-IRSN cooperation of gamma-ray isotopic measurement systems

    SciTech Connect

    Vo, Duc; Wang, Tzu - Fang; Funk, Pierre; Weber, Anne - Laure; Pepin, Nicolas; Karcher, Anna

    2009-01-01

    DOE/NNSA and IRSN collaborated on a study of gamma-ray instruments and analysis methods used to perform isotopic measurements of special nuclear materials. The two agencies agreed to collaborate on the project in response to inconsistencies that were found in the various versions of software and hardware used to determine the isotopic abundances of uranium and plutonium. IRSN used software developed internally to test the MGA and FRAM isotopic analysis codes for criteria used to stop data acquisition. The stop-criterion test revealed several unusual behaviors in both the MGA and FRAM software codes.

  18. On the cross-sensitivity between water vapor mixing ratio and stable isotope measurements of in-situ analyzers

    NASA Astrophysics Data System (ADS)

    Parkes, Stephen; Wang, Lixin; McCabe, Matthew

    2015-04-01

    In recent years there has been an increasing amount of water vapor stable isotope data collected using in-situ instrumentation. A number of papers have characterized the performance of these in-situ analyzers and suggested methods for calibrating raw measurements. The cross-sensitivity of the isotopic measurements on the mixing ratio has been shown to be a major uncertainty and a variety of techniques have been suggested to characterize this inaccuracy. However, most of these are based on relating isotopic ratios to water vapor mixing ratios from in-situ analyzers when the mixing ratio is varied and the isotopic composition kept constant. An additional correction for the span of the isotopic ratio scale is then applied by measuring different isotopic standards. Here we argue that the water vapor cross-sensitivity arises from different instrument responses (span and offset) of the parent H2O isotope and the heavier isotopes, rather than spectral overlap that could cause a true variation in the isotopic ratio with mixing ratio. This is especially relevant for commercial laser optical instruments where absorption lines are well resolved. Thus, the cross-sensitivity determined using more conventional techniques is dependent on the isotopic ratio of the standard used for the characterization, although errors are expected to be small. Consequently, the cross-sensitivity should be determined by characterizing the span and zero offset of each isotope mixing ratio. In fact, this technique makes the span correction for the isotopic ratio redundant. In this work we model the impact of changes in the span and offset of the heavy and light isotopes and illustrate the impact on the cross-sensitivity of the isotopic ratios on water vapor. This clearly shows the importance of determining the zero offset for the two isotopes. The cross-sensitivity of the isotopic ratios on water vapor is then characterized by determining the instrument response for the individual isotopes for a

  19. Chromatic-dispersion measurement by modulation phase-shift method using a Kerr phase-interrogator.

    PubMed

    Baker, Chams; Lu, Yang; Bao, Xiaoyi

    2014-09-22

    We present a novel approach for the measurement of chromatic-dispersion in long optical fibers using a modulation phase-shift method based on a Kerr phase-interrogator. This approach utilizes a Kerr phase-interrogator to measure the phase variation of a sinusoidal optical signal induced by traveling in a fiber under test as the laser carrier wavelength and the sinusoidal signal frequency are varied. Chromatic-dispersion measurement for several fibers including a standard single-mode silica fiber and a dispersion-shifted fiber is experimentally demonstrated. The ultrafast response of the Kerr phase-interrogator opens the way for real-time monitoring of chromatic-dispersion in kilometers-long optical fibers.

  20. Measurement and extinction of vector light shifts using interferometry of spinor condensates

    NASA Astrophysics Data System (ADS)

    Wood, A. Â. A.; Turner, L. Â. D.; Anderson, R. Â. P.

    2016-11-01

    We use differential Ramsey interferometry of ultracold atoms to characterize the vector light shift (VLS) from a far-off-resonance optical dipole trap at λ =1064 nm. The VLS manifests as a "fictitious" magnetic field, which we perceive as a change in the Larmor frequency of two spinor condensates exposed to different intensities of elliptically polarized light. We use our measurement scheme to diagnose the light-induced magnetic field and suppress it to 2.1 (8 ) ×10-4 of its maximum value by making the trapping light linearly polarized with a quarter-wave plate in each beam. Our sensitive measurement of the VLS-induced field demonstrates high-precision, in vacuo interferometric polarimetry of dipole-trapping light and can be adapted to measure vector shifts from other lasers, advancing the application of optically trapped atoms to precision metrology.

  1. Measuring D(d,p)T fusion reactant energy spectra with Doppler shifted fusion products

    SciTech Connect

    Boris, D. R.; Kulcinski, G. L.; Santarius, J. F.; Donovan, D. C.; Piefer, G. R.

    2010-06-15

    Deuterium fusion reactant energy spectra have been measured using a diagnostic that records the Doppler shift imparted to charged particle fusion products of the D(d,p)T reaction by the center-of-mass velocity of the deuterium reactants. This diagnostic, known as the fusion ion Doppler shift diagnostic (FIDO) measures fast deuterium energy spectra in the inertial electrostatic confinement (IEC) experiment at the University of Wisconsin-Madison {l_brace}Santarius et al. [Fusion Sci. Technol. 47, 1238 (2005)]{r_brace}, a device to confine high energy light ions in a spherically symmetric, electrostatic potential well. This article details the first measurements of the fusion reactant energy spectra in an IEC device as well as the design and principles of operation of the FIDO diagnostic. Scaling of reactant energy spectra with a variety of experimental parameters have been explored.

  2. An automatic system for measurement of retardation of wave plates based on phase-shifted method

    NASA Astrophysics Data System (ADS)

    Gao, Zhishan; Yan, Ming

    2005-02-01

    A practical system is described to measure the retardation of wave plates with phase-shifted method. The tested wave plate is put in and the original angle between the axis of it and the analyzer is random, not 45 degree. For the measurement is made rapidly and automatically, a standard wave plate act as a compensator, the stepping motor is used to drive the analyzer to realize phase shifting and a grating encoder is used to measure its rotating angle. At the same time, while the beam comes out from the analyzer, the photoelectric detector gets its intensity, and then the signals is magnified, filtered and sent to computer through its serial port. The results show the system has the advantages of costing little time and high accuracy.

  3. Measurement of sulfur isotope compositions by tunable laser spectroscopy of SO2.

    PubMed

    Christensen, Lance E; Brunner, Benjamin; Truong, Kasey N; Mielke, Randall E; Webster, Christopher R; Coleman, Max

    2007-12-15

    Sulfur isotope measurements offer comprehensive information on the origin and history of natural materials. Tunable laser spectroscopy is a powerful analytical technique for isotope analysis that has proven itself readily adaptable for in situ terrestrial and planetary measurements. Measurements of delta(34)S in SO2 were made using tunable laser spectroscopy of combusted gas samples from six sulfur-bearing solids with delta(34)S ranging from -34 to +22 per thousand (also measured with mass spectrometry). Standard deviation between laser and mass spectrometer measurements was 3.7 per thousand for sample sizes of 200 +/- 75 nmol SO(2). Although SO(2)(g) decreased 9% over 15 min upon entrainment in the analysis cell from wall uptake, observed fractionation was insignificant (+0.2 +/- 0.6 per thousand). We also describe a strong, distinct (33)SO(2) rovibrational transition in the same spectral region, which may enable simultaneous delta(34)S and Delta(33)S measurements.

  4. The stability and calibration of water vapor isotope ratio measurements during long-term deployments

    NASA Astrophysics Data System (ADS)

    Bailey, A.; Noone, D.; Berkelhammer, M.; Steen-Larsen, H. C.; Sato, P.

    2015-10-01

    With the recent advent of commercial laser absorption spectrometers, field studies measuring stable isotope ratios of hydrogen and oxygen in water vapor have proliferated. These pioneering analyses have provided invaluable feedback about best strategies for optimizing instrumental accuracy, yet questions still remain about instrument performance and calibration approaches for multi-year field deployments. With clear scientific potential for using these instruments to carry out monitoring of the hydrological cycle, this study examines the long-term stability of the isotopic biases associated with three cavity-enhanced laser absorption spectrometers - calibrated with different systems and approaches - at two remote field sites: Mauna Loa Observatory, Hawaii, USA, and Greenland Environmental Observatory, Summit, Greenland. The analysis pays particular attention to the stability of measurement dependencies on water vapor concentration and also evaluates whether these so-called concentration dependences are sensitive to statistical curve-fitting choices or measurement hysteresis. The results suggest evidence of monthly-to-seasonal concentration-dependence variability - which likely stems from low signal-to-noise at the humidity-range extremes - but no long-term directional drift. At Mauna Loa, where the isotopic analyzer is calibrated by injection of liquid water standards into a vaporizer, the largest source of inaccuracy in characterizing the concentration dependence stems from an insufficient density of calibration points at low water vapor volume mixing ratios. In comparison, at Summit, the largest source of inaccuracy is measurement hysteresis associated with interactions between the reference vapor, generated by a custom dew point generator, and the sample tubing. Nevertheless, prediction errors associated with correcting the concentration dependence are small compared to total measurement uncertainty. At both sites, changes in measurement repeatability that are

  5. Two-dimensional NMR measurement and point dipole model prediction of paramagnetic shift tensors in solids

    SciTech Connect

    Walder, Brennan J.; Davis, Michael C.; Grandinetti, Philip J.; Dey, Krishna K.; Baltisberger, Jay H.

    2015-01-07

    A new two-dimensional Nuclear Magnetic Resonance (NMR) experiment to separate and correlate the first-order quadrupolar and chemical/paramagnetic shift interactions is described. This experiment, which we call the shifting-d echo experiment, allows a more precise determination of tensor principal components values and their relative orientation. It is designed using the recently introduced symmetry pathway concept. A comparison of the shifting-d experiment with earlier proposed methods is presented and experimentally illustrated in the case of {sup 2}H (I = 1) paramagnetic shift and quadrupolar tensors of CuCl{sub 2}⋅2D{sub 2}O. The benefits of the shifting-d echo experiment over other methods are a factor of two improvement in sensitivity and the suppression of major artifacts. From the 2D lineshape analysis of the shifting-d spectrum, the {sup 2}H quadrupolar coupling parameters are 〈C{sub q}〉 = 118.1 kHz and 〈η{sub q}〉 = 0.88, and the {sup 2}H paramagnetic shift tensor anisotropy parameters are 〈ζ{sub P}〉 = − 152.5 ppm and 〈η{sub P}〉 = 0.91. The orientation of the quadrupolar coupling principal axis system (PAS) relative to the paramagnetic shift anisotropy principal axis system is given by (α,β,γ)=((π)/2 ,(π)/2 ,0). Using a simple ligand hopping model, the tensor parameters in the absence of exchange are estimated. On the basis of this analysis, the instantaneous principal components and orientation of the quadrupolar coupling are found to be in excellent agreement with previous measurements. A new point dipole model for predicting the paramagnetic shift tensor is proposed yielding significantly better agreement than previously used models. In the new model, the dipoles are displaced from nuclei at positions associated with high electron density in the singly occupied molecular orbital predicted from ligand field theory.

  6. Fluorescence emission spectral shift measurements of membrane potential in single cells.

    PubMed

    Kao, W Y; Davis, C E; Kim, Y I; Beach, J M

    2001-08-01

    Previous measurements of transmembrane potential using the electrochromic probe di-8-ANEPPS have used the excitation spectral shift response by alternating excitation between two wavelengths centered at voltage-sensitive portions of the excitation spectrum and recording at a single wavelength near the peak of the emission spectrum. Recently, the emission spectral shift associated with the change in transmembrane potential has been used for continuous membrane potential monitoring. To characterize this form of the electrochromic response from di-8-ANEPPS, we have obtained fluorescence signals from single cells in response to step changes in transmembrane potentials set with a patch electrode, using single wavelength excitation near the peak of the dye absorption spectrum. Fluorescence changes at two wavelengths near voltage-sensitive portions of the emission spectrum and shifts in the complete emission spectrum were determined for emission from plasma membrane and internal membrane. We found that the fluorescence ratio from either dual-wavelength recordings, or from opposite sides of the emission spectrum, varied linearly with the amplitude of the transmembrane potential step between -80 and +60 mV. Voltage dependence of difference spectra exhibit a crossover point near the peak of the emission spectra with approximately equal gain and loss of fluorescence intensity on each side of the spectrum and equal response amplitude for depolarization and hyperpolarization. These results are consistent with an electrochromic mechanism of action and demonstrate how the emission spectral shift response can be used to measure the transmembrane potential in single cells.

  7. Tunable Diode Laser Measurements of Leaf-scale Carbon Isotope Discrimination and Ecosystem Respired Carbon and Oxygen Isotope Ratios in a Semi-arid Woodland

    NASA Astrophysics Data System (ADS)

    McDowell, N.; Chris, B.; Hanson, D.; Kern, S.; Meyer, C.; Pockman, W.; Powers, H.

    2005-12-01

    We present results and speculative interpretation of leaf-level carbon isotope discrimination and ecosystem respired carbon and oxygen isotope ratios from a semi-arid, C3/C4 woodland located in northern New Mexico, USA. Overstory leaf area index (LAI) is dominated by live juniper (Juniperus monosperma) trees with an LAI value of approximately 1.0 m2 per m2 ground area, and has a seasonally dynamic understory of mixed C3 forbs and C4 grasses and cacti, with a maximum LAI of 0.30 m2 per m2 ground area. Ecosystem respired carbon isotope ratios showed values characteristic of C3 dominated photosynthesis (Keeling plot intercepts of -35 to -22 per mil). Seasonal variation was typical of that found in wetter, C3 dominated forests, as was the dependence on climate (e.g. relationships with vapor pressure deficit, soil water content, and canopy conductance). Leaf-level carbon isotope discrimination of the junipers, measured by coupling a Li-Cor 6400 photosynthesis system to the TDL, provided discrimination-Ci and discrimination-vpd relationships consistent with measured ecosystem respired carbon isotope ratios. The oxygen isotope ratio of ecosystem respiration was dependent on rain water isotope composition, but was correlated with soil water content during rain-free periods. The cumulative effect of vapor pressure deficit after a rain event was tightly correlated with the oxygen isotope ratio of ecosystem respiration, suggesting the primary drivers are evaporative enrichment of soil water and perhaps nocturnal leaf enrichment. Instrument precision for carbon and oxygen isotope ratios of carbon dioxide is 0.06 to 0.18 per mil; however, overall precision is somewhat lower due to pressure and sampling effects.

  8. Iron and Nickel Isotope Measurements on SiC X Grains with CHILI

    NASA Astrophysics Data System (ADS)

    Kodolányi, J.; Stephan, T.; Trappitsch, R.; Hoppe, P.; Pignatari, M.; Davis, A. M.; Pellin, M. J.

    2016-08-01

    New measurements with CHILI on SiC X grains provide more detailed Fe and Ni isotope data than previous NanoSIMS analyses. The new data suggest that Fe-Ni fractionation may occur in supernova ejecta before SiC condensation.

  9. Development of Novel Instrumentation to Measure All Nitrous Oxide Mono-Substituted Rare Isotopic Species

    NASA Astrophysics Data System (ADS)

    Du, X.; Leen, J. B.; Gupta, M.; Baer, D. S.

    2015-12-01

    Analysis of isotopic ratios is of great importance to study the sources and sinks of nitrous oxide (N2O) in atmosphere. N2O has four mono-substituted rare isotopic species - 14N15N16O, 15N14N16O, 14N218O, and 14N217O. Here we report on the development of novel instrumentation which is capable of measuring all four N2O isotopic species and therefore enables a complete characterization of abundance variations of these species. This instrument, which employs cavity enhanced absorption technology and a mid-infrared laser, has been developed for simultaneous measurements of all four isotopic species in either a continuous flow mode or a batch mode. A precision of better than 1 per mil for 14N217O has been achieved with samples of 10 ppm N2O in 300 seconds of measurement time. In addition, a precision of better than 1 per mil for 14N15N16O and 15N14N16O and 2 per mil for 14N218O has been achieved with samples of 300 ppb N2O or higher in 300 seconds of measurement time.

  10. Carbon Isotopic Measurements of Amino Acids in Stardust-Returned Samples

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie

    2009-01-01

    NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here, we present the carbon isotopic ratios of glycine and e-aminocaproic acid (EACA), the two most abundant amino acids, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio mass spectrometry coupled with quadrupole mass spectrometry (GC-CAMS/IRMS).

  11. High-accuracy mass measurements of neutron-rich Kr isotopes

    SciTech Connect

    Delahaye, P.; Kellerbauer, A.; Audi, G.; Lunney, D.; Blaum, K.; George, S.; Carrel, F.; Herfurth, F.; Yazidjian, C.; Herlert, A.; Schweikhard, L.; Kluge, H.-J.

    2006-09-15

    The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

  12. Carbon Isotopic Measurements of Amino Acids in Stardust-Returned Samples

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie

    2009-01-01

    NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here, we present the carbon isotopic ratios of glycine and e-aminocaproic acid (EACA), the two most abundant amino acids, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio mass spectrometry coupled with quadrupole mass spectrometry (GC-CAMS/IRMS).

  13. Precision in Strontium Isotope Measurements by Laser Ablation Assisted Resonance Ionization Mass Spectrometry

    SciTech Connect

    Sasada, S.; Tomita, H.; Watanabe, K.; Higuchi, Y.; Kawarabayashi, J.; Iguchi, T.

    2009-03-17

    We have investigated the precision of strontium isotope analysis by Laser Ablation-assisted Resonance Ionization Mass Spectrometry(LA-RIMS). We have confirmed that the mass discrimination effect on the {sup 87}Sr/{sup 86}Sr measurement was reduced by the internal correction method. For the present system, the precision of the isotope ratio of {sup 87}Sr/{sup 86}Sr has been estimated to be 0.6%(1{sigma}). The precision has been limited by the fluctuations with a time scale of less than 10 s.

  14. Progress in AMS measurement of U isotope ratios in nanogram U samples

    NASA Astrophysics Data System (ADS)

    Dong, Kejun; He, Ming; Wang, Chen; Zhao, Xinhong; Li, Lili; Zhao, Yonggang; Wang, Xianggao; Shen, Hongtao; Wang, Xiaoming; Pang, Fangfang; Xu, Yongning; Zhao, Qingzhang; Dou, Liang; Yang, Xuran; Wu, Shaoyong; Lin, Deyu; Li, Kangning; You, Qubo; Bao, Yiwen; Hu, Yueming; Xia, Qingliang; Yin, Xinyi; Jiang, Shan

    2015-10-01

    The determination of uranium isotopic composition in ultra-trace U samples is very important in different fields, especially for the nuclear forensics. A new Accelerator Mass Spectrometry (AMS) technique has been developed for the measurement of uranium isotopic ratios in ng level uranium samples at China Institute of Atomic Energy (CIAE). Recently, the method was further optimized and developed by using a series of blank and standard samples. The results show that the 236U at the femtogram level can be determined in nanogram U samples by the newly developed AMS technique at CIAE. The experimental setup, performances and results will be detailed in this contribution.

  15. Towards high precision measurements of nuclear g-factors for the Be isotopes

    NASA Astrophysics Data System (ADS)

    Takamine, A.; Wada, M.; Okada, K.; Ito, Y.; Schury, P.; Arai, F.; Katayama, I.; Imamura, K.; Ichikawa, Y.; Ueno, H.; Wollnik, H.; Schuessler, H. A.

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of 11Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  16. Technical note: Consistent calculation of aquatic gross production from oxygen triple isotope measurements

    NASA Astrophysics Data System (ADS)

    Kaiser, J.

    2011-07-01

    Oxygen triple isotope measurements can be used to calculate aquatic gross oxygen production rates. Past studies have emphasised the appropriate definition of the 17O excess and often used an approximation to derive production rates from the 17O excess. Here, I show that the calculation can be phrased more consistently and without any approximations using the relative 17O/16O and 18O/16O isotope ratio differences (delta values) directly. I call this the "dual delta method". The 17O excess is merely a mathematical construct and the derived production rate is independent of its definition, provided all calculations are performed with a consistent definition. I focus on the mixed layer, but also show how time series of triple isotope measurements below the mixed layer can be used to derive gross production. In the calculation of mixed layer productivity, I explicitly include isotopic fractionation during gas invasion and evasion, which requires the oxygen supersaturation s to be measured as well. I also suggest how bubble injection could be considered in the same mathematical framework. I distinguish between concentration steady state and isotopic steady state and show that only the latter needs to be assumed in the calculation. It is even possible to derive an estimate of the net production rate in the mixed layer that is independent of the assumption of concentration steady state. I review measurements of the parameters required for the calculation of gross production rates and show how their systematic uncertainties as well as the use of different published calculation methods can cause large variations in the production rates for the same underlying isotope ratios. In particular, the 17O excess of dissolved O2 in equilibrium with atmospheric O2 and the 17O excess of photosynthetic O2 need to be re-measured. Because of these uncertainties, all calculation parameters should always be fully documented and the measured relative isotope ratio differences as well as the

  17. Measurement of the intramolecular isotope effect on aliphatic hydroxylation by Chromobacterium violaceum phenylalanine hydroxylase.

    PubMed

    Panay, Aram J; Fitzpatrick, Paul F

    2010-04-28

    The non-heme iron enzyme phenylalanine hydroxylase from Chromobacterium violaceum has previously been shown to catalyze the hydroxylation of benzylic and aliphatic carbons in addition to the normal aromatic hydroxylation reaction. The intrinsic isotope effect for hydroxylation of 3-cyclochexylalanine by the enzyme was determined in order to gain insight into the reactivity of the iron center. With 3-[(2)H(11)-cyclohexyl]alanine as the substrate, the isotope effect on the k(cat) value was 1, consistent with an additional step in the overall reaction being significantly slower than hydroxylation. Consequently, the isotope effect was determined as an intramolecular effect by measuring the amount of deuterium lost in the hydroxylation of 3-[1,2,3,4,5,6-(2)H(6)-cyclohexyl]alanine. The ratio of 4-HO-cyclohexylalanine that retained deuterium to that which lost one deuterium atom was 2.8. This gave a calculated value of 12.6 for the ratio of the primary deuterium kinetic isotope effect to the secondary isotope effect. This value is consistent with hydrogen atom abstraction by an electrophilic Fe(O) center and a contribution of quantum-mechanical tunneling to the reaction.

  18. Measurements of pressure-induced shifts in the 1-0 and 2-0 bands of HF and in the 2-0 bands of HCl-35 and HCl-37. [for planetary atmosphere IR spectroscopy

    NASA Technical Reports Server (NTRS)

    Guelachvili, G.; Smith, M. A. H.

    1978-01-01

    Fourier absorption spectra of HCl and HF measured at room temperature and low pressures were found to indicate pressure-induced shifts of the spectral lines at gas pressures of only 10 torr. Self-induced shifts were determined for the HF 2-0 band and for the HCl-35 and HCl-37 2-0 bands, and shift oscillations in the 2-0 bands due to near-resonant dipole-dipole interactions between the two gases were also evaluated. Separate measurements of pressure-induced shifts in the HF 1-0 and 2-0 bands and in both isotopic HCl bands were obtained using argon, neon, nitrogen, and CO2 separately as the perturbing gases.

  19. Averaging of random walks and shift-invariant measures on a Hilbert space

    NASA Astrophysics Data System (ADS)

    Sakbaev, V. Zh.

    2017-06-01

    We study random walks in a Hilbert space H and representations using them of solutions of the Cauchy problem for differential equations whose initial conditions are numerical functions on H. We construct a finitely additive analogue of the Lebesgue measure: a nonnegative finitely additive measure λ that is defined on a minimal subset ring of an infinite-dimensional Hilbert space H containing all infinite-dimensional rectangles with absolutely converging products of the side lengths and is invariant under shifts and rotations in H. We define the Hilbert space H of equivalence classes of complex-valued functions on H that are square integrable with respect to a shift-invariant measure λ. Using averaging of the shift operator in H over random vectors in H with a distribution given by a one-parameter semigroup (with respect to convolution) of Gaussian measures on H, we define a one-parameter semigroup of contracting self-adjoint transformations on H, whose generator is called the diffusion operator. We obtain a representation of solutions of the Cauchy problem for the Schrödinger equation whose Hamiltonian is the diffusion operator.

  20. Use of Stimulated Emission to Measure R-Line Shifts in Shocked Ruby Crystals

    SciTech Connect

    Gupta, Y.M.; Knudson, M.D.

    1999-06-24

    In previous studies, ruby R-line shifts under shock compression and tension have been measured using the spontaneous luminescence from optically pumped samples. Signal intensities obtained through the use of this method are limited by the short time duration of the experiments (100 ns to several ps) in comparison to the long lifetime of the luminescence (approximately 3 ins). We have investigated the use of stimulated emission as a technique for measuring R-line shifts in shocked ruby crystals. Feasibility experiments were performed both at ambient conditions and under shock compression to 60 kbar using an experimental configuration similar to that used for time resolved ruby luminescence measurements in previous shock wave studies. Signal gain due to stimulated emission was observed, with gains ranging from 1.1 to 3.4, in agreement with calculations performed for the particular experimental configuration used. The present results make a good case for incorporating this technique to measure shock induced R-line shifts in ruby. Work supported by DSWA.

  1. High-accuracy time- and space-resolved Stark shift measurements

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1996-07-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. The authors use simultaneous 2-D-spatial and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion variation, and sensitivity. A semi-automated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {+-}2--4%. Detailed tests of the fitting procedure confirm that the wavelength shift uncertainties are accurate to better than {+-}20%. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain 3-D space- and time-resolved measurements of the electric and magnetic fields is in progress.

  2. High-accuracy time- and space-resolved Stark shift measurements (invited)

    SciTech Connect

    Bailey, J.E.; Adams, R.; Carlson, A.L.; Ching, C.H.; Filuk, A.B.; Lake, P.

    1997-01-01

    Stark-shift measurements using emission spectroscopy are a powerful tool for advancing understanding in many plasma physics experiments. We use simultaneous two-dimensional space- and time-resolved spectra to study the electric field evolution in the 20 TW Particle Beam Fusion Accelerator II ion diode acceleration gap. Fiber optic arrays transport light from the gap to remote streaked spectrographs operated in a multiplexed mode that enables recording time-resolved spectra from eight spatial locations on a single instrument. Design optimization and characterization measurements of the multiplexed spectrograph properties include the astigmatism, resolution, dispersion, and sensitivity. A semiautomated line-fitting procedure determines the Stark shift and the related uncertainties. Fields up to 10 MV/cm are measured with an accuracy {plus_minus}2{percent}{endash}4{percent}. Detailed tests of the procedure confirm that the uncertainty in the wavelength-shift error bars is less than {plus_minus}20{percent}. Development of an active spectroscopy probe technique that uses laser-induced fluorescence from an injected atomic beam to obtain three-dimensional space- and time-resolved measurements of the electric and magnetic fields is in progress. {copyright} {ital 1997 American Institute of Physics.}

  3. Reconciling the Differences between the Measurements of CO2 Isotopes by the Phoenix and MSL Landers

    NASA Technical Reports Server (NTRS)

    Niles, P. B.; Mahaffy, P. R.; Atreya, S.; Pavlov, A. A.; Trainer, M.; Webster, C. R.; Wong, M.

    2014-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars. There have been several different measurements by landers and Earth based systems performed in recent years that have not been in agreement. In particular, measurements of the isotopic composition of martian atmospheric CO2 by the Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory (MSL) are in stark disagreement. This work attempts to use measurements of mass 45 and mass 46 of martian atmospheric CO2 by the SAM and TEGA instruments to search for agreement as a first step towards reaching a consensus measurement that might be supported by data from both instruments.

  4. Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Composition Measurements

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Christian, E. R.; Cummings, A. C.; deNolfo, G. A.; Israel, M. H.; Leske, R. A.; Mewaldt, R. A,; Stone, E. C.; vonRosevinge, T. T.; Wiedenbeck, M. E.

    2013-01-01

    The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly Ne-22/Ne-20, Fe-58/Fe-56, and Ga-31/Ge -32 show that the composition is consistent with source material that is a mix of approx 80% ISM (with Solar System abundances) and 20% outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an approx 80%/20% mix rather than pure ISM, that the refractory and volatile elements have similar slopes, and that refractory elements are preferentially accelerated by a factor of approx 4. We conclude that these data are consistent with an OB association origin of GCRs.

  5. A stable isotope dilution method for measuring bioavailability of organic contaminants

    PubMed Central

    Delgado-Moreno, Laura; Gan, Jay

    2014-01-01

    Methods for determining bioavailability of organic contaminants suffer various operational limitations. We explored the use of stable isotope labeled references in developing an isotope dilution method (IDM) to measure the exchangeable pool (E) of pyrene and bifenthrin as an approximation of their bioavailability in sediments. The exchange of deuterated bifenthrin or pyrene with its native counterpart was completed within 48 h. The derived E was 38–82% for pyrene and 28–59% for bifenthrin. Regression between E and the sum of rapid and slow desorption fractions obtained from sequential desorption showed a slope close to 1.0. The ability of IDM to predict bioavailability was further shown from a strong relationship (r2 > 0.93) between E and bioaccumulation into Chironomus tentans. Given the abundance of stable isotope labeled references and their relatively easy analysis, the IDM has the potential to become a readily adoptable tool for estimating organic contaminants bioaccessibility in various matrices. PMID:23434573

  6. Measurement of helium isotopes in soil gas as an indicator of tritium groundwater contamination.

    PubMed

    Olsen, Khris B; Dresel, P Evan; Evans, John C; McMahon, William J; Poreda, Robert

    2006-05-01

    The focus of this study was to define the shape and extent of tritium groundwater contamination emanating from a legacy burial ground and to identify vadose zone sources of tritium using helium isotopes (3He and 4He) in soil gas. Helium isotopes were measured in soil-gas samples collected from 70 sampling points around the perimeter and downgradient of a burial ground that contains buried radioactive solid waste. The soil-gas samples were analyzed for helium isotopes using rare gas mass spectrometry. 3He/4He ratios, reported as normalized to the air ratio (RA), were used to locate the tritium groundwater plume emanating from the burial ground. The 3He (excess) suggested that the general location of the tritium source is within the burial ground. This study clearly demonstrated the efficacy of the 3He method for application to similar sites elsewhere within the DOE weapons complex.

  7. Shifts in bryophyte carbon isotope ratio across an elevation × soil age matrix on Mauna Loa, Hawaii: do bryophytes behave like vascular plants?

    PubMed

    Waite, Mashuri; Sack, Lawren

    2011-05-01

    The carbon isotope ratio (δ(13)C) of vascular plant leaf tissue is determined by isotope discrimination, primarily mediated by stomatal and mesophyll diffusion resistances and by photosynthetic rate. These effects lead to predictable trends in leaf δ(13)C across natural gradients of elevation, irradiance and nutrient supply. Less is known about shifts in δ(13)C for bryophytes at landscape scale, as bryophytes lack stomata in the dominant gametophyte phase, and thus lack active control over CO(2) diffusion. Twelve bryophyte species were sampled across a matrix of elevation and soil ages on Mauna Loa, Hawaii Island. We tested hypotheses based on previous findings for vascular plants, which tend to have less negative δ(13)C at higher elevations or irradiances, and for leaves with higher leaf mass per area (LMA). Across the matrix, bryophytes spanned the range of δ(13)C values typical of C(3) vascular plants. Bryophytes were remarkably similar to vascular plants in exhibiting less negative δ(13)C with increasing elevation, and with lower overstory cover; additionally δ(13)C was related to bryophyte canopy projected mass per area, a trait analogous to LMA in vascular plants, also correlated negatively with overstory cover. The similarity of responses of δ(13)C in bryophytes and vascular plants to environmental factors, despite differing morphologies and diffusion pathways, points to a strong direct role of photosynthetic rate in determining δ(13)C variation at the landscape scale.

  8. Trustworthiness of measurement devices in round-robin differential-phase-shift quantum key distribution

    NASA Astrophysics Data System (ADS)

    Cao, Zhu; Yin, Zhen-Qiang; Han, Zheng-Fu

    2016-02-01

    Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) has been proposed to raise the noise tolerability of the channel. However, in practice, the measurement device in RRDPS QKD may be imperfect. Here, we show that, with these imperfections, the security of RRDPS may be damaged by proposing two attacks for RRDPS systems with uncharacterized measurement devices. One is valid even for a system with unit total efficiency, while the other is valid even when a single-photon state is sent. To prevent these attacks, either security arguments need to be fundamentally revised or further practical assumptions on the measurement device should be put.

  9. Carbon and Oxygen Stable Isotope Measurements of Martian Atmospheric CO2 by the Phoenix Lander

    NASA Technical Reports Server (NTRS)

    Niles, Paul B.; Boynton, W. V.; Hoffman, J. H.; Ming, D. W.; Hamara, D.

    2010-01-01

    Precise stable isotope measurements of the CO2 in the martian atmosphere have the potential to provide important constraints for our understanding of the history of volatiles, the carbon cycle, current atmospheric processes, and the degree of water/rock interaction on Mars [1]. The isotopic composition of the martian atmosphere has been measured using a number of different methods (Table 1), however a precise value (<1%) has yet to be achieved. Given the elevated Delta(sup 13)C values measured in carbonates in martian meteorites [2-4] it has been proposed that the martian atmosphere was enriched in 13C [8]. This was supported by measurements of trapped CO2 gas in EETA 79001[2] which showed elevated Delta(sup 13)C values (Table 1). More recently, Earth-based spectroscopic measurements of the martian atmosphere have measured the martian CO2 to be depleted in C-13 relative to CO2 in the terrestrial atmosphere[ 7, 9-11]. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Mars Phoenix Lander [12] included a magnetic-sector mass spectrometer (EGA) [13] which had the goal of measuring the isotopic composition of martian atmospheric CO2 to within 0.5%. The mass spectrometer is a miniature instrument intended to measure both the martian atmosphere as well as gases evolved from heating martian soils.

  10. Measurement of the Two-Loop Lamb Shift in Lithiumlike U{sup 89+}

    SciTech Connect

    Beiersdorfer, P.; Chen, H.; Thorn, D.B.; Traebert, E.

    2005-12-02

    Using the SuperEBIT electron beam ion trap, we have measured the 2s{sub 1/2}-2p{sub 1/2} transitions in U{sup 88+} and U{sup 89+}. The measured value of 280.645{+-}0.015 eV for Li-like U{sup 89+} improves the available precision by nearly an order of magnitude and establishes a new benchmark for testing the total QED contribution to the transition energy within a fractional accuracy of 3.6x10{sup -4}. We infer a value for the 2s two-loop Lamb shift in U{sup 89+} of -0.23 eV, from which we estimate a value of -1.27 eV for the 1s two-loop Lamb shift in U{sup 91+}.

  11. Measurement of the two-loop lamb shift in lithiumlike U89+.

    PubMed

    Beiersdorfer, P; Chen, H; Thorn, D B; Träbert, E

    2005-12-02

    Using the SuperEBIT electron beam ion trap, we have measured the 2s(1/2)-2p(1/2) transitions in U88+ and U89+. The measured value of 280.645 +/- 0.015 eV for Li-like U89+ improves the available precision by nearly an order of magnitude and establishes a new benchmark for testing the total QED contribution to the transition energy within a fractional accuracy of 3.6 x 10(-4). We infer a value for the 2s two-loop Lamb shift in U89+ of -0.23 eV, from which we estimate a value of -1.27 eV for the 1s two-loop Lamb shift in U91+.

  12. Measurement of the two-loop Lamb shift in lithiumlike U89+

    SciTech Connect

    Beiersdorfer, P; Chen, H; Thorn, D B; Trabert, E

    2005-04-01

    Using the SuperEBIT electron beam ion trap we have measured the 2s{sub 1/2}-2p{sub 1/2} transitions in U{sup 88+} and U{sup 89+}. The value of 280.645 {+-} 0.015 eV for Li-like U{sup 89+} improves the available precision by nearly an order of magnitude and establishes a new benchmark for testing QED, including higher-order contributions, within a fractional accuracy of better than 3 x 10{sup -4}. From our measurement, we infer a value for both the 2s and 1s two-loop Lamb shift, yielding excellent agreement with recent calculations of the 1.26 eV 1s two-loop Lamb shift in U{sup 91+}.

  13. High-speed measurement of an air transect's temperature shift heated by laser beam

    NASA Astrophysics Data System (ADS)

    Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

    2005-02-01

    Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

  14. Is health, measured by work ability index, affected by 12-hour rotating shift schedules?